Pertussis toxin-sensitive G proteins influence nitric oxide synthase III activity and protein levels in rat heart

Inhibitory G protein activity (Gi) and nitric oxide (NO) modulate muscarinic-cholinergic (MC) inhibition of cardiac beta-adrenergic inotropic responses. We hypothesized that Gi mediates MC-NO synthase (NOS) signal transduction. Isoproterenol (0.2-0.8 microg/min) and acetylcholine (1 microM) were administered to isolated perfused rat hearts pretreated with saline (controls; n = 8) or pertussis toxin (PT; 30 microg/kg intraperitoneally 3 d before study; n = 20). PT abrogated in vitro ADP-ribosylation of Gi protein alpha subunit(s) indicating near-total decrease in Gi protein function. Isoproterenol increased peak +dP/dt in both control (peak isoproterenol effect: +2, 589+/-293 mmHg/s, P < 0.0001) and PT hearts (+3,879+/-474 mmHg/s, P < 0.0001). Acetylcholine reversed isoproterenol inotropy in controls (108+/-21% reduction of +dP/dt response, P = 0.001), but had no effect in PT hearts. In controls, NG-monomethyl-L-arginine (100 microM) reduced basal +dP/dt, augmented isoproterenol +dP/dt (peak effect: +4,634+/-690 mmHg/s, P < 0.0001), and reduced the MC inhibitory effect to 69+/-8% (P < 0.03 vs. baseline). L-arginine (100 M) had no effect in controls but in PT hearts decreased basal +dP/dt by 1, 426+/-456 mmHg/s (P < 0.005), downward-shifted the isoproterenol concentration-effect curve, and produced a small MC inhibitory effect (27+/-4% reduction, P < 0.05). This enhanced response to NO substrate was associated with increased NOS III protein abundance, and a three- to fivefold increase in in vitro calcium-dependent NOS activity. Neomycin (1 microM) inhibition of phospholipase C did not reverse L-arginine enhancement of MC inhibitory effects. These data support a primary role for Gi in MC receptor signal transduction with NOS in rat heart, and demonstrate regulatory linkage between Gi and NOS III protein levels.     

Low-dose cyclosporine and mycophenolate mofetil in renal allograft recipients with suboptimal renal function

BACKGROUND: Cyclosporine (CsA) nephrotoxicity can be identified by functional changes and chronic renal damage. CsA-associated renal fibrosis has been related to the overproduction of transforming growth factor (TGF)-beta1, a fibrogenic cytokine. Mycophenolate mofetil (MMF) may allow CsA dose reduction without increasing the risk of rejection. METHODS: We studied the impact of CsA dose reduction in association with MMF on renal function and TGF-beta1, production in 16 long-term renal allograft recipients with suspected CsA nephrotoxicity. Two grams/day of MMF were introduced, and CsA dose was reduced to reach whole-blood levels between 40 and 60 ng/ml within 1 month. CsA dose and levels, renal function parameters, and platelet-poor plasma TGF-beta1 levels were evaluated before and 6 months thereafter. RESULTS: MMF allowed a decrease in both the mean dose of CsA (3.8+/-1.35 vs. 2.2+/-0.73 mg/kg/day; P<0.01) and CsA levels (148+/-36 vs. 53+/-19 ng/ml; P<0.001). The reduction of CsA was associated with a decrement of serum creatinine levels (210+/-46 vs. 172+/-41 micromol/L; P<0.001) and an increase in both the glomerular filtration rate (32.9+/-12 vs. 39.1+/-14 ml/min/1.73 m2; P<0.02) and renal plasma flow (195+/-79 to 218.6+/-74.02 ml/min/1.73 m2; P<0.02). There was a reduction in plasma TGF-beta1 levels (4.6+/-4.2 vs. 2.0+/-1.4 ng/ml; P=0.003) and CsA levels correlated with TGF-beta1 (r=0.536, P=0.002). No rejection episodes occurred, and an improvement in both systolic (149+/-13 vs. 137+/-12 mmHg; P<0.01) and diastolic blood pressure (89+/-14 vs. 83+/-10 mmHg; P<0.04) were observed. CONCLUSIONS: These short-term results show that MMF introduction allows a CsA dose reduction, which improves renal function, reduces TGF-beta1 production, and improves the control of hypertension, without increasing the incidence of acute rejection.     

Effect of chronotropic and inotropic stimulation on the coronary pressure-flow relation in left ventricular hypertrophy

Left ventricular hypertrophy (LVH) secondary to chronic pressure overload is associated with increased susceptibility to myocardial hypoperfusion and ischemia during increased cardiac work. The present study was performed to study the effects of chronotropic and inotropic stimulation on the coronary pressure-flow relation of the hypertrophied left ventricle of dogs and to determine the individual contributions of increases in heart rate and contractility to the exaggerated exercise-induced increases in effective back pressure (pressure at zero flow; Pzf). Ascending aortic banding in seven dogs increased the LV to body weight ratio to 7.7 +/- 0.3 g/kg compared to 4.8 +/- 0.2 g/kg in 10 normal dogs (p < or = 0.01). Maximum coronary vasodilation was produced by intracoronary infusion of adenosine. During resting conditions maximum coronary blood flow in the pressure overloaded hypertrophied left ventricle was impaired by both an increase in Pzf (25.1 +/- 2.6 vs 13.8 +/- 1.2 mmHg in hypertrophied vs normal ventricles, respectively, p < or = 0.01) and a decrease in maximum coronary conductance (slope of the linear part of the pressure-flow relation, slopep > or = linear) (8.6 +/- 1.1 vs 12.7 +/- 0.9 ml/min/mmHg, p < or = 0.01). Right atrial pacing at 200 and 250 beats/min resulted in similar rightward shifts of the pressure-flow relation in hypertrophied and normal hearts with 3.1 +/- 0.8 and 4.7 +/- 0.8 mmHg increases in Pzf in LVH and normal dogs, respectively; stepwise multivariate regression analysis indicated that the exaggerated decrease in filling pressure (10 +/- 2 vs 6 +/-2 mmHg) and decrease in left ventricular systolic pressure (45 +/- 5 vs 3 +/- 3 mmHg, p < or = 0.01) may have blunted a greater rightward shift of the pressure-flow relation produced by atrial pacing in the hypertrophied hearts. Inotropic stimulation with dobutamine (10-20 micrograms/kg/min, i.v.) resulted in minimal flow changes in normal hearts but produced a 4.4 +/- 1.5 mmHg (p < or = 0.05) rightward shift of the pressure-flow relation in hypertrophied hearts. which correlated with a greater increase in left ventricular systolic pressure (83 +/- 16 vs 18 +/- 4 mmHg. p < or = 0.05). Exercise resulted in a rightward shift in both normal and hypertrophied left ventricles, but the increase in Pzf was significantly greater in the hypertrophied hearts (15.2 +/- 0.9 vs 10.3 +/- 0.9 mmHg. p < or = 0.05). Stepwise multivariate regression analysis indicated that not only increases in left ventricular filling pressure, but also increases in heart rate and LV systolic pressure contributed to the abnormally great increase in effective coronary back pressure which results in limitation of myocardial perfusion during exercise in the pressure overloaded hypertrophied left ventricle.     

Kawasaki disease

This study was conducted to investigate the functional and morphological aspects of orthotopic lung xenograft rejection in a concordant hamster-to-rat donor-recipient species combination. By postoperative day (POD) 3, allotransplanted grafts demonstrated good aeration, but infiltrates were seen in all the xenotransplanted lungs. Antihamster lymphocytotoxic antibody titers increased to 5.2 +/- 1.1 by POD 3 (P < 0.05 vs POD 1) and reached 7.0 +/- 0.8 by POD 5 (P < 0.05 vs PODs 1 and 3). The CD4+/CD8+ ratio in peripheral blood lymphocytes increased significantly on POD 3 (P < 0.05 vs untransplanted), but decreased by POD 5 (P < 0.05). Histologically, on POD 3 the xenotransplanted grafts were characterized by perivascular cellular infiltrates and edema. Cytologically, the cells consisted of small round lymphocytes, monocytes, and occasional neutrophils. Immunohistochemical analysis showed heavy IgM and C3 deposits in the vascular endothelium, without any IgG deposits. Allotransplanted grafts showed moderate W 3/25 + (28.3 +/- 17.3%) and MRC OX8 + (38.7 +/- 0.7%) cellular infiltrations on POD 3, but ED1 + (8.0 +/- 3.7%) cells were rare. Conversely, in the xenotransplanted grafts, ED1 + (34.2 +/- 16.4%) cells were more prevalent than MRC OX8 + (18.1 +/- 16.5%) cells on POD 3, at P < 0.01 and P < 0.05 vs allograft, respectively. These results indicate that both antidonor antibodies and macrophages/monocytes play an important role in the concordant lung xenograft rejection.     

Effects of pharmacological autonomic blockade on dual atrioventricular nodal pathways physiology in patients with slow-fast atrioventricular nodal reentrant tachycardia

The purpose of this study was to investigate the atrioventricular AV nodal physiology and the inducibility of AV nodal reentrant tachycardia (AVNRT) under pharmacological autonomic blockade (AB). Seventeen consecutive patients (6 men and 11 women, mean age 39 +/- 17 years) with clinical recurrent slow-fast AVNRT received electrophysiological study before and after pharmacological AB with atropine (0.04 mg/kg) and propranolol (0.2 mg/kg). In baseline, all 17 patients could be induced with AVNRT, 5 were isoproterenol-dependent. After pharmacological AB, 12 (71%) of 17 patients still demonstrated AV nodal duality. AVNRT became noninducible in 7 of 12 nonisoproterenol dependent patients and remained noninducible in all 5 isoproterenol dependent patients. The sinus cycle length (801 +/- 105 ms vs 630 +/- 80 ms, P < 0.005) and AV blocking cycle length (365 +/- 64 ms vs 338 +/- 61 ms, P < 0.005) became shorter after AB. The antegrade effective refractory period and functional refractory period of the fast pathway (369 +/- 67 ms vs 305 +/- 73 ms, P < 0.005; 408 +/- 56 ms vs 350 +/- 62 ms, P < 0.005) and the slow pathway (271 +/- 30 ms vs 258 +/- 27 ms, P < 0.01; 344 +/- 60 ms vs 295 +/- 50 ms, P < 0.005) likewise became significantly shortened. However, the ventriculoatrial blocking cycle length (349 +/- 94 ms vs 326 +/- 89 ms, NS) and effective refractory period of retrograde fast pathway (228 +/- 38 ms vs 240 +/- 80 ms, NS) remained unchanged after autonomic blockade. Pharmacological AB unveiling the intrinsic AV nodal physiology could result in the masking of AV nodal duality and the decreased inducibility of clinical AVNRT.     

Comparative study of the effects of ouabain and digoxin on blood pressure of rats

OBJECTIVE: To compare the effect of ouabain on the blood pressure of rats with that of digoxin to find the evidences of the relationship between endogenous ouabain (EO) and development of hypertension. METHODS: Sprague-Dawley rats, which were divided into 3 groups, were infused with ouabain (23 x 75 micrograms.kg-1/day, i.p.), digoxin (36 x 84 micrograms.kg-1/day, i.p.) and normal saline (NS) once a day respectively. Systolic blood pressure and body weight were recorded weekly. Five weeks later, rats of ouabain group were randomly assigned to three infusion subgroups: Oc group, continued with ouabain infusion; Od group, added digoxin (73 x 68 micrograms.kg-1/day, i.p.) and Os group, stopped administration of ouabain. Another week later, direct blood pressure was recorded in aorta. Systolic and diastolic cardiac function, plasma renin activity and aldosterone levels of all the rats were measured. RESULTS: After a latent period of one week, blood pressure of Ouabain group increased significantly [95.4 +/- 11.8 mmHg (1 mmHg = 0.133 kPa) at the beginning of the experiment vs 122.5 +/- 16.9 mmHg at the end of week 6, P < 0.05] with normal plasma renin activity and higher aldosterone (1.28 +/- 0.45 ng/ml vs 0.69 +/- 0.27 ng/ml, P < 0.05). The blood pressure decreased after either withdrawal of ouabain or addition of digoxin (116.3 +/- 14.4 mmHg vs 100 +/- 10.7 mmHg, P < 0.05; 123.9 +/- 13.9 vs 103.3 +/- 10.5 mmHg, P < 0.05, respectively). No difference of blood pressure was found between the digoxin and NS group. CONCLUSIONS: Our results suggested that EO might be one of the causes of the development of hypertension. Aldosterone might play some role in the mechanism of ouabain-induced hypertension. Digoxin can not induce hypertension. There is a great difference between the effect of ouabain and digoxin on the blood pressure. Moreover, digoxin can reverse the hypertension induced by ouabain.     

Contribution of nitric oxide to the acute antihypertensive effect of blockers of AT1 angiotensin receptors in spontaneously hypertensive rats

The acute vasodepressor effect of AT1 angiotensin receptor blockers losartan and CL329167 was compared in spontaneously hypertensive rats (SHR) pretreated and not pretreated with NG-monomethyl-L-arginine (LNMMA; 15 mg/kg i.v. bolus plus infusion at 10 mg/kg/h), an inhibitor of nitric oxide (NO) synthesis. The antihypertensive effect of losartan (30 mg/kg, i.v.) in SHR pretreated with LNMMA (-13 +/- 4 mmHg) was greatly diminished (P < 0.01) relative to the antihypertensive effect of losartan in SHR not pretreated with LNMMA (-44 +/- 8 mmHg). Similarly, the antihypertensive effect of CL329167 (5 mg/kg, i.v.) in SHR pretreated with LNMMA (-12 +/- 3 mmHg) was surpassed (P < 0.01) by the antihypertensive effect in SHR not pretreated with LNMMA. (-41 +/- 4 mmHg). However, pretreatment of SHR with LNMMA did not minimize the vasodepressor effect of prazosin, isoproterenol or sodium nitroprusside. The impairment in vasodepressor responsiveness to losartan in rats pretreated with LNMMA was not demonstrable in rats concurrently receiving sodium nitroprusside to correct for the loss of endogenous NO, or atrial natriuretic peptide which also increases vascular cGMP. These data suggest that a mechanism mediated by NO and/or cGMP is necessary for the full expression of the acute antihypertensive effect of AT1 angiotensin receptor blockers in SHR.     

Surgical resection for hepatocellular carcinoma in Cape Town--a clinical and histopathological study

BACKGROUND: The effect of mycophenolate mofetil (MMF) and sirolimus (rapamycin, RAPA) mono- and combination-therapy was examined in prevention of acute heart, pancreas, and kidney allograft rejection and in reversal of ongoing heart allograft rejection in the rat. METHODS: Both drugs were administered orally for up to 30 days. Eleven groups (n=6) were involved in the first part of the heart allografting model. Brown Norway (RT1n) to Lewis (RT1(1)) combination was used in the heart and pancreas transplantation models, whereas Buffalo (RT1b) to Wistar Furth (RT1u) was used in the kidney transplantation model. RESULTS: The naive control group showed a mean survival time of 6.5+/-0.6 days. There were graded dose-responses to monotherapy of MMF 10 and 20 mg(kg/ day (12.5+/-2.6 days; 19.3+/-9.0 days) and RAPA 0.2, 0.4, 0.8, and 1.8 mg/kg/day (19.2+/-2.0 days; 30.0+/-7.3 days; 50.8+/-12.5 days; 51.2+/-2.6 days), respectively (P=0.001). Results with the combined use of drugs indicate that a synergistic or very strong synergistic interaction was produced when compared with monotherapy of MMF or RAPA: MMF 10 mg(kg/day+RAPA 0.2 mg/kg(day (52.7+/-5.7 days, combination index [CI] =0.189), MMF 20 mg(kg/day+RAPA 0.2 mg/kg/day (57.7+/-5.7 days, CI=0.084), MMF 10 mg/kg/day+RAPA 0.4 mg(kg/day (50.2+/-13.5 days, CI=0.453), and MMF 20 mg/kg(day+ RAPA 0.4 mg/kg(day (51.5+/-6.8 days, CI=0.439), respectively. These results were repeatable in the prevention of acute pancreas and kidney allograft rejection in the rat. In the second part of the study of reversal of ongoing acute heart allograft rejection model, the combined treatment of MMF 10 mg/kg(day+RAPA 0.2 mg/ kg(day (35.5+/-16.0 days, CI=0.794) and MMF 20 mg/kg day+RAPA 0.2 mg(kg/day (57.2+/-4.7 days, CI=0.310) represented synergistic interaction compared with monotherapy of MMF or RAPA. CONCLUSIONS: Concomitant therapy of MMF and RAPA produces a synergistic effect in prevention of heart, pancreas, and kidney allograft rejection and in reversal of ongoing heart allograft rejection in the rat.     

A prospective randomized comparison of quadruple versus triple therapy for first cadaver transplants with immediate function

In January 1988, we initiated a prospective, randomized comparison of prophylactic antilymphoblast globulin (ALG; quadruple therapy) versus no prophylactic ALG (triple therapy) in the setting of immediate graft function (defined by a brisk diuresis and a 20% decline in serum creatinine within 24 hr). Recipients were stratified according to presence of diabetes and age greater or less than 50 years. Recipients on quadruple therapy (n = 61) received 7 days of prophylactic Minnesota ALG (5 mg/kg on day 1, 10 mg/kg on day 2, 20 mg/kg on days 3-7). CsA, 10 mg/kg/day, began on day 6. AZA began at 2.5 mg/kg/day and was adjusted according to white blood cell count. Recipients on triple therapy (n = 60) began immediate CsA, 10 mg/kg/day orally and AZA, 5 mg/kg/day, tapering to 2.5 mg/kg/day by day 8. Both groups received identical prednisone tapers beginning at 1 mg/kg/day, decreasing to 0.5 mg/kg/day by 2 weeks and to 0.15 mg/kg/day by 6 months. Demographic characteristics between groups were not different with respect to diabetes, age, sex, race, per cent panel-reactive antibodies (PRA), or HLA matching. Follow-up ranged from 2 to 4.5 years. Patient survival was 93% for the quadruple therapy group and 90% for triple therapy. Actuarial graft survival was 79% in the quadruple group and 72% in the triple group (P = 0.18). Graft loss due to rejection occurred in 6/61 receiving ALG versus 7/60 in the immediate CsA group. Three of 4 high PRA recipients in the immediate CsA group lost their grafts within 30 days compared with none in the ALG group. The mean time to graft loss was significantly longer for the quadruple therapy group (17 +/- 8 months) compared with the triple therapy group (4 +/- 5 months), P = 0.006. The total number of rejection episodes was similar for both groups (29/61 vs. 31/60), as was the number who were rejection free (51% vs. 47%). The use of OKT3 was also similar between groups (28% vs. 30%). The quadruple therapy group had a higher incidence of CMV infection: 20% vs. 7% (P < 0.05), but no grafts or patients were lost as a result. Serum Cr was not different at 1 and 12 months (1.5 and 1.6 vs. 1.6 and 1.7, respectively), nor were Cr clearances (63 and 68 vs. 60 and 63). Conclusion. Early initiation of oral CsA in the setting of immediate graft function is not associated with significant nephrotoxicity.(ABSTRACT TRUNCATED AT 400 WORDS)     

Formulation and in vitro and in vivo availability of diclofenac sodium enteric-coated beads

OBJECTIVE: The beneficial effects of weight loss with a very-low-calorie diet (VLCD) on cardiovascular risk factors have been reported at the end of energy restriction. As the effects, especially on blood pressure, may not remain constant during weight maintenance, we studied the longer-term effects of weight loss on 24h ambulatory blood pressure (ABP), lipids, glucose and insulin. DESIGN: Prospective study of a 17-week weight loss programme containing an eight-week VLCD period and follow-up visit at one-year. SUBJECTS: Twenty-nine moderately obese, normotensive or mildly hypertensive women. The mean +/- s.d. body mass index (BMI) was 36.0 +/- 2.6 kg/m2 and mean age 40.3 +/- 8.3 y. RESULTS: In the last week of the VLCD, the mean (s.d.) weight loss was 12.4 +/- 3.3 kg (P < 0.001), at the end of the programme 15.1 +/- 4.4 kg (P < 0.001 vs baseline), and at one-year follow-up 10.7 +/- 7.6 kg (P < 0.001 vs baseline). Mean 24 h ABP decreased 8.0/4.6 mmHg (P < 0.001 for both) on the last week of the VLCD, at the end of the programme, the systolic ABP decrease was 4.7 mmHg (P < 0.01 vs baseline) and diastolic 2.1 mmHg (not statistically significant (NS) vs baseline). At one-year follow-up, the mean systolic ABP decrease was 4.1 mmHg (P < 0.01 vs baseline) and mean diastolic 3.0 mmHg (P < 0.05 vs baseline). Sodium excretion decreased 55 mmol/24 h in the last VLCD week (P < 0.01) and returned to baseline after that. At the one-year follow-up, beneficial changes, compared with baseline, were observed in mean serum glucose (-0.28 mmol/l, P < 0.05), triglyceride (-0.35 mmol/l, P < 0.01) and HDL cholesterol (+0.16 mmol/l, P < 0.001). CONCLUSIONS: This weight loss programme with a VLCD enabled obese subjects to lose weight and decrease cardiovascular risks. Despite some regain in weight during follow-up, the beneficial effects were overall maintained over the year. Sodium intake tended to increase during follow-up. Information on sodium restriction should be included in weight loss programmes.     

Interaction of the allogeneic state and hypercholesterolemia in arterial lesion formation in experimental cardiac allografts

To learn more about the interaction of allogeneic transplantation and hypercholesterolemia in the formation of arterial lesions, we performed heterotopic cardiac transplantation in rabbits. We analyzed lesions in both the coronary arteries and the proximal ascending aorta 6 weeks after surgery in both transplanted and native hearts of normocholesterolemic rabbits and those with diet-induced hypercholesterolemia (serum cholesterol, 1638 +/- 366 mg/dL, n = 6, 6 weeks after transplantation). All animals received cyclosporin A (5 mg.kg-1.d-1) for immunosuppression. The transplanted aortas of hypercholesterolemic animals had thicker intimal lesions than did the native aortas (intima/media ratio, 0.67 +/- 0.4 versus 0.08 +/- 0.1, P < .05) and contained more T cells (37.4 +/- 12.8 versus 5.7 +/- 6.2 per high-power field, P < .001). In normocholesterolemic animals (n = 5) the coronary arteries had negligible lesions in the native heart and only slight and inconsistent intimal lesions in the transplanted heart. In the hypercholesterolemic animals, more coronary arteries had intimal lesions in the transplanted hearts than in the native hearts (74% versus 43%). Coronary artery lesions in the native hearts consisted mostly of foam cells, while those in transplanted hearts had more abundant smooth muscle cells as determined by alpha-actin staining. Intimal endothelial cells in transplanted aortas expressed increased levels of vascular cell adhesion molecule-1 and intracellular adhesion molecule-1 compared with the native vessels subjected to identical levels of cholesterolemia. Medial smooth muscle cells in transplanted aortas contained much higher levels of immunoreactive tumor necrosis factor-alpha than did medial cells of the native aorta in the same hypercholesterolemic animals. The intima of transplanted aortas contained prominent microvessels compared with the native aorta of the hypercholesterolemic rabbits. We conclude that even during treatment with doses of cyclosporine that control acute myocardial rejection, hypercholesterolemia and the allogeneic state act together to augment allograft atherosclerosis, T-cell accumulation, intimal neovascularization, local cytokine expression, and indices of cell activation in arteries.     

Tilidine does not affect human sphincter of Oddi motility--a randomized, controlled study

AIM: To investigate the effects of intravenous pentazocine and tilidine on sphincter of Oddi motility. METHODS: Twenty patients with suspected sphincter of Oddi dysfunction were enrolled in a prospective, double-blind study. Sphincter of Oddi motility was assessed by means of endoscopic manometry after injection of 0.9% saline, as well as after randomized dosing with either 30 mg pentazocine i.v. (n = 10) or 50 mg tilidine i.v. (n = 10). RESULTS: Pentazocine significantly increased the sphincter of Oddi baseline pressure from 32 +/- 21 mmHg (saline) to 41 +/- 19 mmHg (P = 0.002), whereas tilidine did not alter the sphincter baseline pressure (34 +/- 15 mmHg saline vs. 36 +/- 16 mmHg tilidine, P = 0.16). Furthermore, pentazocine increased the phasic sphincter contraction amplitude (108 +/- 16 mmHg saline vs. 121 +/- 18 mmHg pentazocine, P = 0.004), but tilidine was without any effect (125 +/- 24 mmHg saline vs. 125 +/- 21 mmHg tilidine, P = 0.93). The phasic sphincter of Oddi contraction frequency and duration were not influenced either by pentazocine or by tilidine. CONCLUSION: In contrast to 30 mg of pentazocine, 50 mg of tilidine does not affect sphincter of Oddi motility. Therefore, tilidine can be used during endoscopic manometry and for analgesia in pancreatobiliary disease.     

Chronic viral hepatitis enhances the risk of infection but not acute rejection in renal transplant recipients

To assess the impact of chronic viral hepatitis on host immune response, we analyzed the incidence of acute rejection and the frequency of infections in 86 patients infected with hepatitis B and C viruses and had developed clinical evidence of chronic liver disease and 1283 control patients who were transplanted at our center during the same period, but had no evidence of chronic viral hepatitis. To compare the mean number of rejections and the mean number of infections between the two groups, we used multivariate linear regression analysis, which allowed us to adjust simultaneously for the effects of 10 other risk variables with potential impact on graft rejection and posttransplant infection. During a mean follow up of 5.3+/-5.2 years, 62% of hepatitis patients and 54% of control patients had experienced an acute rejection (P=NS). The mean rejections/patient in the hepatitis group was 1.3+/-0.14 versus 1.03+/-0.03 in control (P=NS). In the linear regression analysis, the number of acute rejections in the hepatitis group was 0.16 higher than in control (P=NS). With reference to infection, 84% of hepatitis patients experienced an infectious complication in the posttransplant period, compared with 75% in the control (P=0.05). The mean number of infections/patient was 5.7+/-0.73 in the hepatitis group compared with 3.9+/-0.14 in the control group (P=0.002). The linear regression model had shown that the hepatitis group had a relative increase of 1.18 infections/pt, compared with control. Of the different sites of infection, the hepatitis group had a significant increase in bloodstream (0.48+/-0.08 vs. 0.25+/-0.02) P=0.003; pulmonary (0.60+/-0.09 vs. 0.38+/-0.03) P=0.03; and CNS infections (0.08+/-0.03 vs. 0.02+/-0.004) P=0.05 compared with control. Among the different microorganisms causing infection, the hepatitis patients had a significant increase in gram negative bacterial infections compared with the control group (74% vs. 61%) P=0.04. Our data suggest that chronic viral hepatitis is associated with a significant increase in overall infections, and that of potentially fatal infections involving CNS, lungs and bloodstream. Since there is no significant increase in the rate of graft rejection, one could consider a cautious reduction in the doses of maintenance immunosuppressive agents in renal transplant patients with chronic viral hepatitis. The reduced immunosuppression may in turn lower the death rate from sepsis and progressive hepatic failure.     

Hemodynamic effects of a calcium channel promoter, BAY y 5959, are preserved after chronic administration in ischemic heart failure in conscious dogs

BAY y 5959 is a dihydropyridine derivative that binds to L-type calcium channels in a voltage-dependent manner and promotes calcium entry into the cell during the plateau of the action potential by influencing mean open time. Because myofilament responsiveness to calcium is preserved in congestive heart failure (CHF), the inotropic responsiveness to this compound should be preserved in CHF, and tolerance should not develop despite long-term treatment. To test these hypotheses, CHF was induced in 14 chronically instrumented dogs by daily (30 +/- 5 days) intracoronary microsphere injections. The effects of BAY y 5959 (2-h i.v. infusions of 3 microg/kg/min and 10 microg/kg/min) were determined before heart failure, after heart failure was established and then 2 h after the end of a 5-day continuous BAY y 5959 intra-atrial infusion. Before CHF, the positive inotropic effect of BAY y 5959 at a dose of 10 microg/kg/min [left ventricular dP/dt (LVdP/dt) increased from 2955 +/- 132 mmHg to 4897 +/- 426 mmHg, P < .05] was associated with bradycardia (HR decreased from 92 +/- 4 to 78 +/- 6 b/min, P <.05), slight increases in mean arterial pressure (it increased from 100 +/- 2 mmHg to 113 +/- 5 mmHg, P <.05) and did not alter left ventricular end-diastolic pressure. In CHF, BAY y 5959 continued to induce dose-dependent increases in left ventricular systolic pressure, LVdP/dt and mean arterial pressure, as well as causing bradycardia and a significant decrease in left ventricular end-diastolic pressure. After a 5-day infusion of BAY y 5959, base-line LVdP/dt and left ventricular end-diastolic pressure improved. The responses of LVdP/dt and mean arterial pressure to BAY y 5959 were similar to those of the control state. The sustained responses in CHF and after long-term infusion suggest that BAY y 5959 may be an effective and potent inotropic agent for treatment of CHF that does not lead to tolerance to its positive inotropic effects.     

Intracellular glucose metabolism after long term metabolic control with glyburide: improved glucose oxidation with unchanged glycogen synthase activity

To determine whether improved metabolic control with long term glyburide treatment alters intracellular glucose metabolism independent of effects on glucose uptake (GU), we studied eight obese patients with noninsulin-dependent diabetes mellitus before and 7 months after glyburide therapy. Indirect calorimetry and skeletal muscle biopsies were performed in the basal state and during 300 pmol/m2.min insulin infusions, with glucose turnover rates determined by [3-3H]glucose turnover. During the glucose clamps, rates of GU were matched before and after treatment using equivalent hyperinsulinemia and variable levels of hyperglycemia. After glyburide treatment, rates of GU were decreased in the basal state [4.16 +/- 0.57 vs. 3.29 +/- 0.37 mg/kg fat free mass (FFM)/min; P < 0.05], but similar during glucose clamps (11.53 +/- 1.42 vs. 11.93 +/- 1.32 mg/kg FFM.min; P = NS) according to study design. In both the basal state and during glucose clamps after glyburide therapy, rates of glucose oxidative metabolism (Gox) increased by 68-78% [1.21 +/- 0.16 vs. 2.03 +/- 0.31 mg/kg FFM.min (P < 0.05) and 3.13 +/- 0.51 vs. 5.58 +/- 0.55 mg/kg FFM.min (P < 0.05), respectively], and rates of nonoxidative glucose metabolism decreased [2.96 +/- 0.68 vs. 1.25 +/- 0.21 mg/kg FFM.min (P < 0.05) and 8.40 +/- 1.50 to 6.30 +/- 1.40 mg/kg FFM.min (P < 0.01), respectively]. Circulating plasma FFA levels and rates of fat oxidation (Fox) remained unchanged in both the basal state and during clamp studies. Skeletal muscle glycogen synthase (GS) activity, expressed as fractional velocity, was unchanged by glyburide therapy (2.2 +/- 0.8 vs. 2.7 +/- 0.3% in the basal state and 7.3 +/- 1.8 vs. 6.1 +/- 0.9% during clamps; both P = NS). In summary, at both matched (during clamp studies) and unmatched (during basal studies) rates of GU, improved metabolic control with glyburide therapy resulted in marked improvement of Gox independent of the effects on GU. The improvement in Gox was not associated with changes in Fox, circulating FFA, or muscle GS activity. These data indicate that long term metabolic control achieved by glyburide therapy markedly improves Gox, but not skeletal muscle GS activity, in noninsulin-dependent diabetes mellitus independent of GU and Fox.     

Diastolic dysfunction coincides with early mild transplant rejection: in situ measurements in a heterotopic rat heart transplant model

BACKGROUND: Diastolic dysfunction seen in early clinical transplant rejection has been difficult to demonstrate in experimental rodent models because of the inability to make sensitive in situ measurements of systolic and diastolic functions. We have developed a heterotopic heart transplant model with Fisher 344 and ACI rats (without immunosuppression), where in situ measurements of diastolic and systolic functions were made sequentially (daily) by use of an implanted left ventricular balloon. METHODS: Syngeneic and allogeneic heterotopic heart transplants were performed. In situ function was determined by varying balloon volume to measure the developed pressure, the rates of pressure rise (+dp/dt) and pressure fall (-dp/dt), diastolic pressure-volume relationship, and the time constant of diastolic relaxation (tau). These results were compared with function measurements in transplanted hearts that were excised and perfused in a Langendorff mode (ex vivo) during the same posttransplantation period. RESULTS: Histologic examination revealed that at day 3 after transplantation, allografts showed mild lymphocytic infiltration indicative of mild or early rejection, and by day 5, there was severe rejection with myocyte necrosis. By day 3, the slope of the diastolic pressure-volume relationship (ie, left ventricular stiffness) was significantly higher in allografts as compared with isografts (436 +/- 96 vs 177 +/- 26 mm Hg/mL, p < .05). Similarly, tau was significantly longer in allografts by day 3 after transplantation. Developed pressure and +dp/dt became significantly lower in allografts beginning on day 6. Function measurements made in the isolated perfused ex vivo hearts yielded the same results at day 3 after transplantation as the in situ group of hearts. CONCLUSION: Using a chronically implanted left ventricular balloon, we have developed a heterotopic heart transplant model where sensitive measurements of systolic and diastolic functions can be made. With this preparation, the early changes in the diastolic dysfunction seen clinically can be reproducibly detected. Thus this model may be useful to study mechanisms and interventions during early transplant rejection.     

Epidural anaesthesia for caesarean delivery in triple and quadruple pregnancies

BACKGROUND: Mechanical and/or hormonal factors may increase the spread of epidural anaesthesia in pregnancy, and hormonal changes are more pronounced in high-order pregnancies. However, no previous study has evaluated the dose requirements and haemodynamic effects of epidural anaesthesia for caesarean delivery in this latter situation. METHODS: The anaesthetic requirements to obtain a T4 upper sensory level were retrospectively compared in triple (n = 19) or quadruple (n = 2) pregnancies to 31 singleton pregnancies who received epidural anaesthesia for elective caesarean delivery using 2% lidocaine with 1/200,000 adrenaline. RESULTS: In high-order pregnancies, the gestational age at delivery was lower than in singleton pregnancies (34.9 +/- 1.9 weeks vs 38.2 +/- 1.1 weeks; P = 0.0001) whereas maternal body weight (76.5 +/- 8.7 kg vs 73.4 +/- 14.8 kg; NS) and lidocaine requirements (428 +/- 95 mg vs 426 +/- 98 mg; NS) were similar. Moreover, although the overall incidence of hypotension was not different (multiple pregnancy; 65% vs 58% in singletons), ephedrine (5.4 +/- 5.3 mg vs 10.7 +/- 13.8 mg; P < 0.05) and additional fluid requirements during onset of the block (4.3 +/- 1.7 mL/kg vs 5.3 +/- 2.6 mL/kg; P = 0.03) were less than in singletons. CONCLUSION: We found surprisingly similar anaesthetic requirements for epidural anaesthesia in high-order and singleton pregnancies. Mechanical factors may have played an important role. Moreover, the need for ephedrine and fluids was less in high-order pregnancies. This could be related to more pronounced physiological changes or to different physician attitudes.     

In obesity, glucose load loses its early inhibitory, but maintains its late stimulatory, effect on somatotrope secretion

Glucose load has a biphasic effect on GH secretion. In fact, in normal subjects, glucose load has a prompt inhibitory and a late stimulatory effect on both spontaneous and GHRH-induced GH levels. The mechanism underlying the inhibitory effect is probably mediated by the increase in hypothalamic somatostatin, whereas that underlying the stimulatory effect is unclear. On the other hand, in obesity, a reduced somatotrope responsiveness to all GH secretagogues is well known, whereas recently, we found that glucose load, but not pirenzepine and somatostatin, fails to inhibit the GHRH-induced GH rise. Thus, the inhibitory effect of hyperglycemia on GH secretion is selectively lacking in obesity. The aim of the present study was to verify whether in obesity the late stimulatory effect of glucose on GH secretion is preserved. We studied 15 female obese patients (OB; age, 33.9 +/- 2.6 yr; body mass index, 36.4 +/- 1.5 kg/m2; waist/hip ratio, 0.9 +/- 0.1) and 12 normal female subjects (NS; 26.5 +/- 1.0 yr; 21.4 +/- 0.3 kg/m2) as controls. Two studies were performed. In study A (six OB and six NS) we evaluated the somatotrope response to GHRH (1 microgram/kg, i.v., at 0 min) alone or preceded by oral glucose (OGTT; 100 g, orally, at -45 min). In study B (nine OB and six NS) we studied the somatotrope response to OGTT (100 g, orally, at 0 min), saline plus GHRH (1 microgram/kg, iv, at 150 min), and OGTT plus GHRH. In study A, the GHRH-induced GH rise in NS was higher (P < 0.01) than that in OB. OGTT blunted the GHRH-induced GH rise in NS (0-90 min area under the curve, 318.9 +/- 39.1 vs. 696.3 +/- 110.8 micrograms/min-L; P < 0.05), but failed to modify it in OB (289.1 +/- 51.7 vs. 283.9 +/- 44.0 micrograms/min-L). In study B, the GHRH-induced GH rise in NS was higher (P < 0.01) than that in OB. OGTT induced a late GH increase in both NS (150-240 min area under the curve, 249.6 +/- 45.2 micrograms/min-L) and OB (103.2 +/- 31.4 micrograms/min-L). Moreover, OGTT enhanced the GHRH-induced GH rise in NS as well as in OB [1433.0 +/- 202.0 vs. 967.9 +/- 116.3 micrograms/min-L (P < 0.03) and 763.8 +/- 131.0 vs. 278.1 +/- 52.3 micrograms/min-L (P < 0.01), respectively]. The GH responses to OGTT alone and combined with GHRH in OB were lower (P < 0.03) than those in NS. Our data show that in human obesity, the oral glucose load loses its precocious inhibitory effect on the GHRH-induced GH rise but maintains its late stimulatory effect on somatotrope secretion. These findings suggest that the inhibitory and stimulatory effects of glucose load on GH secretion are unlikely to be due to biphasic modulation of hypothalamic somatostatin release, which seems selectively refractory to stimulation by hyperglycemia in obesity.     

The ETA receptor antagonist, BMS-182874, reduces acute hypoxic pulmonary hypertension in pigs in vivo

OBJECTIVE: Elevated levels of the potent vasoactive peptide endothelin (ET), have been found in pathophysiological conditions associated with pulmonary hypertension. In this study, we have investigated the effects of the ETA receptor antagonist, BMS-182874, on hypoxic pulmonary hypertension in pigs. METHODS: Pigs were subjected to acute, intermittent 15-min periods of hypoxia (FiO2 0.1). Following a first hypoxia establishing hypoxic baseline values, vehicle or BMS-182874 (10 or 30 mg/kg) was administered i.v. before a second hypoxic period. In separate groups of animals, the effects of the nitric oxide synthase inhibitor N omega-nitro-L-arginine (L-NNA) in combination with BMS-182874 (10 mg) during repeated hypoxia were investigated. The ET-1-blocking properties of BMS-182874 were studied in vivo by infusion of ET-1 during normoxia and in vitro using isolated porcine pulmonary arteries. RESULTS: The hypoxia-evoked increase in mean pulmonary artery pressure was reduced by administration of BMS-182874 (10 mg/kg i.v.; from 42 +/- 8 to 34 +/- 4 mmHg, P < 0.05 and 30 mg/kg i.v.; from 38 +/- 4 to 30 +/- 5 mmHg, P < 0.05). In addition, BMS-182874 at 30 mg/kg reduced the pulmonary vascular resistance during hypoxia (from 7.4 +/- 1.5 to 5.3 +/- 1.1 mmHg.min.l-1 P < 0.05). The hemodynamic response to repeated hypoxia was reproducible in control animals and unaffected by the cyclo-oxygenase inhibitor diclophenac (3 mg/kg). Infusion of L-NNA alone resulted in an augmented pulmonary vasoconstriction during hypoxia; pulmonary arterial pressure from 35 +/- 6 to 43 +/- 9 mmHg; P < 0.05 and vascular resistance from 7.2 +/- 1.1 to 9.9 +/- 1.8 mmHg.min.l-1; P < 0.05. L-NNA in combination with BMS-182874 (10 mg/kg) resulted in a hypoxic pulmonary vasoconstriction of similar magnitude as hypoxic baseline. In addition, BMS-182874 reduced the hemodynamic response to ET-1 in normoxic pigs and competitively antagonized the vasoconstrictor effect of ET-1 in isolated porcine pulmonary arteries. CONCLUSIONS: The non-peptide, selective ETA receptor antagonist, BMS-182874, reduces hypoxic pulmonary vasoconstriction in pigs. The reduction in pulmonary vascular response to hypoxia following BMS-182874 is at least partly independent of nitric oxide.     

Autonomic contribution to the blood pressure and heart rate variability changes in early experimental hyperthyroidism

A great deal of uncertainty persists regarding the exact nature of the interaction between autonomic nervous activity and thyroid hormones in the control of heart rate (HR) and blood pressure (BP). Thyrotoxicosis was produced by a daily intraperitoneal (i.p.) injection of L-thyroxine (0.5 mg/kg body wt in 1 ml of 5 mM NaOH for 5 days). Control rats received i.p. daily injections of the thyroxine solvant. Autonomic blockers were administered intravenously: atropine (0.5 mg/kg), atenolol (1 mg/kg), atenolol + atropine or prazosin (1 mg/kg). Eight animals were studied in each group. Thyroxine treatment was sufficient to induce a significant degree of tachycardia (423 +/- 6 vs 353 +/- 4 bpm; p < 0.001, unpaired Student's tests), systolic BP elevation (142 +/- 3 vs 127 +/- 2 mmHg; p < 0.001), pulse pressure increase (51 +/- 2 vs 41 +/- 2 mmHg, p < 0.01), cardiac hypertrophy (1.165 +/- 0.017 vs 1.006 +/- 0.012 g, p < 0.001), weight loss (-21 +/- 2 g; p < 0.001) and hyperthermia (37.8 +/- 0.1 vs 37.0 +/- 0.1 degrees C, p < 0.001). The intrinsic HR observed after double blockade (atenolol + atropine) was markedly increased after treatment with thyroxine (497 +/- 16 vs 373 +/- 10 bpm, p < 0.05). Vagal tone (difference between HR obtained after atenolol and intrinsic HR) was positively linearly related to intrinsic HR (r = 0.84; p < 0.01). Atenolol neither modified HR nor BP variability in rats with hyperthyrodism. The thyrotoxicosis was associated with a reduction of the 0.4 Hz component of BP variability (analyses on 102.4 sec segments, modulus 1.10 +/- 0.07 vs 1.41 +/- 0.06 mmHg; p < 0.01). Prazosin was without effect on this 0.4 Hz component in these animals. These data show a functional diminution of the vascular and cardiac sympathetic tone in experimental hyperthyroidism. Increased intrinsic HR resulting from the direct effect of thyroid hormone on the sinoatrial node is the main determinant of a tachycardia leading to a subsequent rise in cardiac output. The resulting BP elevation could reflexly induce a vagal activation and a sympathetic (vascular and cardiac) inhibition.