Influence of some antirheumatic drugs and cytostatics on urinary enzyme level

In experiments with rats, the influence of the treatment with sodium salicylate (350 mg/kg), phenylbutazone (100 mg/kg), cyclophosphamide (5 mg/kg), 6-mercaptopurine (25 mg/kg) and D-penicillamine (50 mg/kg), on urinary lactate dehydrogenase, leucine aminopeptidase and alanine aminopeptidase was investigated. All these drugs caused an increase in the enzyme levels in urine. In the case of sodium salicylate, the increase occurred only after the first administration of the drug; phenylbutazone caused a gradual increase of the enzymes. Cytostatic drugs caused an increase in the level of the investigated enzymes in urine with a maximum after 1 week of treatment.     

Activity of various immunosuppressive drugs on tuberculin hypersensitivity reaction in chickens

Drug induced immunosuppression of chicken immune response was studied in F1 hybrids of the CB and IC inbred lines. In tuberculin reaction complete inhibition of wattle swelling was induced by the administration of methotrexate, colcemid (1 mg/KBW), and 6-mercaptopurine. The cellular infiltration was substantially reduced in these cases. Cyclophosphamide and colcemid (0.1 mg/KBW) reduced partially the wattle swelling but had no apparent effect on the cellular infiltration. Acetinomycin D did not affect in measurable degree the wattle swelling. The histologic picture was in this case the same as in the control animals. The same drug administration schedule had less pronounced effect on anti-HSA antibody production. No anti-HSA antibody was found after the 500 mg/animal doses of 6-mercaptopurine. Significant reduction of anti-HSA titres was found after 50 mg/animal doses of 6-mercaptopurine, colcemid (1 mg/KBW), 25 MG/KBW or cyclophosphamide and after the methotrexate treatment.     

Frontal systems dysfunction in children with attention-deficit/hyperactivity disorder and learning disabilities

OBJECTIVES: Our aim was to study the relationships between clinical efficacy of azathioprine, 6-mercaptopurine pharmacokinetics and changes in peripheral blood lymphocyte subpopulations induced by azathioprine treatment in Crohn's disease. METHODS: Twenty-three patients were prospectively followed up for 1 year. Peripheral blood counts, total lymphocytes, CD3+, CD4+, CD8+, CD25+, CD16+CD56+, CD57+ and CD19+ lymphocyte subpopulations were carried out, using flow cytometry, during azathioprine treatment. Pharmacokinetic studies were performed at day 8 and month 3 by measuring 6-mercaptopurine plasma concentration after an oral dose of azathioprine (2 mg/kg). Results were compared in responders (no activity and no steroids) and non-responders. RESULTS: The decrease in peripheral blood leukocytes and neutrophils was significant after 1 month, reaching 49% and 48% of the pre-treatment values at 1 year; the one of lymphocytes was significant after 6 months and reached 41% at 1 year. Percentages of CD3+, CD4+, CD8+, CD57+, CD16+CD56+ and CD19+ lymphocytes remained unchanged whereas percentage of CD25+ lymphocytes increased from 10% to 28% (P < 0.01). There was a high inter and intraindividual variability of 6-mercaptopurine peak plasma concentration and area under the curve. No significant difference was found between responders (n = 14) and non responders (n = 7) for pharmacokinetic parameters and lymphocyte subpopulations; there was no correlation between lymphocyte subpopulation changes and 6-mercaptopurine pharmacokinetics. CONCLUSION: Monitoring of 6-mercaptopurine plasma concentration and blood lymphocyte subpopulations is of little value in Crohn's disease patients treated with azathioprine.     

A randomized trial in primary biliary cirrhosis comparing ursodeoxycholic acid in daily doses of either 10 mg/kg or 20 mg/kg. Dutch Multicentre PBC Study Group

BACKGROUND: Ursodeoxycholic acid (UDCA) prolongs transplantation-free survival in primary biliary cirrhosis (PBC). However, the optimal therapeutic dose has not been established. AIM: To compare the effects of UDCA administered in daily doses of 10 vs. 20 mg/kg on symptoms, liver biochemistry and biliary UDCA enrichment. METHODS: A 6-month multicentre randomized open controlled trial was conducted to assess the effects of an increase in the dose of UDCA to 20 mg/kg/day vs. continuation of 10 mg/kg/day for patients who had not achieved biochemical normalization during treatment for at least 6 months with the 10 mg/kg dose. Clinical and laboratory evaluations were performed at entry and at 3-month intervals. The percentage UDCA in duodenal bile was assessed at entry and at 6 months. RESULTS: Sixty-one patients were enrolled. No side-effects of UDCA were observed. Within the 20 mg/kg/day group significant decreases were found for alkaline phosphatase (- 8%; P = 0.003), aspartate aminotransferase (- 11%; P = 0.01), alanine aminotransferase (- 17%; P < 0.001), gamma-glutamyl transferase (- 34%; P < 0.001), immunoglobulin M (- 11%; P = 0.002) and cholesterol (- 8.1%; P < 0.001). In the 10 mg/kg group none of these parameters differed significantly from baseline. No significant differences between dose groups for symptom scores or serum bilirubin were found. Biliary enrichment with UDCA increased from 37% to 46% in the 20 mg/kg group (P = 0.02) while remaining stable in the 10 mg/kg group. CONCLUSIONS: Liver biochemistry improved in PBC patients receiving UDCA 20 mg/kg/day compared to a dose of 10 mg/kg/day. Both doses were equally well tolerated. These results indicate that UDCA 10 mg/kg/ day is a suboptimal dose for treating PBC.     

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)     

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.     

Developmental toxicity evaluation of isopropanol by gavage in rats and rabbits

Timed-pregnant CD (Sprague-Dawley) rats, 25/group, were dosed orally with aqueous isopropanol (IPA; CAS No. 67-63-0) solutions at 0, 400, 800, or 1200 mg/kg/day, once daily on Gestational Days (GD) 6 through 15 at a dosing volume of 5 ml/kg. Artificially inseminated New Zealand white rabbits, 15/group, were dosed orally with IPA at 0, 120, 240, or 480 mg/kg/day once daily on GD 6 through 18 at 2 ml/kg. Maternal body weights, clinical observations, and food consumption were recorded throughout gestation for both species. At scheduled euthanization for both species (GD 20, rats; GD 30, rabbits), fetuses were weighed, sexed, and examined for external, visceral (including craniofacial) and skeletal alterations. For both species, the pregnancy rate was high and equivalent across all groups; no dams or does aborted, delivered early, or were removed from study. In rats, two dams (8%) died at 1200 mg/kg/day and one dam (4%) died at 800 mg/kg/day. Maternal body weights and weight gain were equivalent across all groups, except for statistically significantly reduced gestational weight gain (GD 0-20; 89.9% of control value), associated with statistically significantly reduced gravid uterine weight at 1200 mg/kg/day (89.2% of control value). There were no treatment-related clinical signs or effects on maternal food consumption. All gestational parameters evaluated were equivalent across groups, including pre- and postimplantation loss, fetal sex ratios, and litter size. Twenty-two to 25 litters were examined per group. Fetal body weights per litter were statistically significantly reduced at the two highest doses (97.3 (n.s.), 94.7, and 94.3% of controls at 800 mg/kg/day and 92.1, 91.9, and 95.4% of controls at 1200 mg/kg/day for all fetuses and males and females separately). No evidence of increased teratogenicity was observed at any dose tested in rats. In rabbits, four does (26.7%) died at 480 mg/kg/day. Maternal body weights were statistically significantly reduced during treatment (GD 6-18) at 480 mg/kg/day (45.4% of control value) with a nonsignificant reduction in gestational weight change (GD 0-30; 77.3% of control value) at this dose. Profound clinical signs of toxicity and statistically significantly reduced maternal food consumption were observed at 480 mg/kg/day. All gestational parameters were equivalent across all doses administered. Thirteen to 15 litters were evaluated per group except for the 480 mg/kg/day group with 11 litters (due to maternal deaths). There were no treatment-related effects on pre- or postimplantation loss, fetal sex ratio, litter size, or fetal body weight/litter. Moreover, no evidence was found of increased teratogenicity at any dose tested in rabbits. Therefore, IPA was not teratogenic to CD rats or to NZW rabbits. The NOAELS for both maternal and developmental toxicity were 400 mg/kg/day in rats, and were 240 and 480 mg/kg/day, respectively, in rabbits.     

Analysis of hepatocyte distribution and survival in vascular beds with cells marked by 99mTC or endogenous dipeptidyl peptidase IV activity

The present study was designed to clarify the effects of TJ-8117 on apoptosis in the glomeruli of 5/6 nephrectomized rats. TJ-8117 (400 mg/kg/day), captopril (50 mg/kg/day) and nicardipine (50 mg/kg/day) were administered as drinking water from the 56th day after renal ablation, and continued throughout the experiment. All rats were sacrificed at 13 weeks and renal tissues were removed to quantify histopathological and apoptotic parameters in glomeruli. TJ-8117 inhibited proteinuria, matrix index and decrease in the number of total cells in glomeruli of nephrectomized rats. In addition, the increase in apoptotic body and DNA fragmentation was significantly inhibited in the TJ-8117-treated group. Captopril and nicardipine failed to inhibit both parameters. In 400 mg/kg of the TJ-8117 treated group, the number of Bcl -2 positive cells in the glomeruli was elevated compared with the 5/6 nephrectomized control group. In addition, the number of Bax positive cells in the TJ-8117 group was significantly suppressed in a dose-dependent manner. These results suggest that TJ-8117 may inhibit apoptosis in the late stage of this model by suppressing matrix accumulation and progression of glomerulosclerosis. The apoptosis-preventing effect may be mediated by decreased expression of Bax in the glomerular cells.     

Compomers and glass ionomers: bond strength to dentin and mechanical properties

Twenty-six patients with newly diagnosed ALL (age range 15-49 years, median 32 years) received treatment comprising: cycles 1 and 2: adriamycin 30 mg/m2 days 1-3, vincristine: 2 mg days 1, 8, and 15, with prednisolone 40 mg daily, given until complete remission (CR). L-asparaginase 10000 units/m2, days 1-14, was given only with the first cycle. Cycle 3 consisted of 100 mg/m2 etoposide orally, days 1-5, and 1 gm/m2 bd cytosine arabinoside (ara-C) days 1-5. Cycles 1-3 were then repeated. Intrathecal methotrexate (MTX) 12.5 mg was given on day 1 of each treatment cycle. The first 12 consecutive patients received this chemotherapy alone, the subsequent 14 received, in addition, 3 micrograms/kg GM-CSF subcutaneously, from day 4 of cycles 1,2,4 and 5 (and from day 6 of cycles 3 and 6) until the absolute neutrophil count had reached 0.5 x 10(9)/1. All patients in whom CR was achieved then received prophylactic cranial irradiation. With the exception of those with T-ALL, this was followed by oral maintenance therapy consisting of 6-mercaptopurine, MTX, and cyclophosphamide for 3 years. Patients receiving GM-CSF did not have shorter intercycle times or a lower incidence of documented infections than those who did not receive it. The CR rate was 89% overall-uninfluenced by GM-CSF, but higher than that achieved previously at St Bartholomew's Hospital in an equivalent age-group.     

Seminal vesicles are novel sites of luteinizing hormone/human chorionic gonadotropin-receptor gene expression

The effect of pentoxifylline (PTX) was tested for its capacity to modulate cytokine responses during therapy of severe Plasmodium falciparum malaria in a placebo-controlled, randomized study in 45 adult patients in Bangkok, Thailand. The patients received standard antimalarial treatment with artesunate (120 mg intravenously given immediately, then 60 mg every 12 hr for a total dose of 600 mg). The patients received either low-dose PTX (20 mg/kg/day, n = 15), high-dose PTX (40 mg/kg/day, n = 15), or placebo (n = 15) as continuous infusion for the first three days of antimalarial treatment. Tumor necrosis factor (TNF) and interleukin-6 (IL-6) plasma levels were markedly elevated in all patients prior to treatment. After 6 hr of high-dose PTX treatment, TNF and IL-6 levels significantly decreased while an increase in TNF and IL-6 levels was seen after 6 hr of low-dose PTX or placebo treatment (P < 0.01). After 12 and 24 hr of high-dose PTX infusion, TNF-receptor plasma concentrations were lower than in low-dose PTX- or placebo-treated patients (P < 0.01), whereas no differences between the groups with regard to IL-6 receptor levels were observed. We conclude that 40 mg/kg/day of PTX reduces plasma levels of TNF, IL-6, and TNF-receptor in patients with severe malaria. Whether this reduction improves clinical outcome remains to be determined.     

Gap-junction disassembly and connexin 43 dephosphorylation induced by 18 beta-glycyrrhetinic acid

In two Segment II Teratology studies, timed-pregnant Crl:CD[BR] (Sprague-Dawley) rats were treated orally (gastric intubation) on days 6-15 of gestation with ibutilide fumarate (ibutilide), a class III antiarrhythmic that has been shown to increase the refractory period and action potential duration of myocardial cells. In the first study, ibutilide does of 20, 40, and 80 mg/kg/ day were tested. Although maternal toxicity was equivocal in the 80 mg/kg/day group, all 23 rats that conceived had entirely resorbed liters when the animals were killed on day 20 of gestation. Similarly, 12 of 24 litters were completely resorbed in the 40 mg/kg/day group, with an 87.7% postimplantational loss. Of the surviving fetuses in this group, 48.6% had at least one malformation. The incidences of malformed pharynx and malformed palate, along with adactyly, were statistically significantly higher in this group than in the control group. In addition, a significant (P < 0.05) increase in total malformations (5.7% of the fetuses), relative to the controls (0.8%), was found for the 20 mg/kg/day group. Since a no observed adverse effect level (NOAEL) was not found, a second teratology study was performed. In this study, the ibutilide doses were 5, 10, and 20 mg/kg/day. The 20 mg/kg/day dose was again teratogenic with 9.2% of the fetuses malformed, as compared to a control value of 1.0%. Also, the incidences of scoliosis and interventricular septal defect were statistically significantly higher in this group. Although statistically significant differences were not detected, scoliosis was also found in the 10 mg/kg/day group (3 fetuses in 2 litters), along with a significant dose-response trend for this malformation. As the result, the NOAEL for ibutilide teratogenicity in rats was set at 5 mg/kg/day. This dose is 4 times the proposed maximum clinical dose (two 1 mg doses, each infused over 10 minutes, or 0.033 mg/kg for a 60 kg person), when corrected for 2.6% oral bioavailability in the rat at a dose of 10 mg/kg, as determined in separate studies.     

Evaluation of the developmental toxicity of methacrylonitrile in Sprague-Dawley rats and New Zealand white rabbits

Timed-pregnant Sprague-Dawley (CD) outbred rats and New Zealand White rabbits were dosed by gavage with methacrylonitrile (MACR) in distilled water during major organogenesis. Rats were dosed on Gestational Days (GD) 6 through 15 (0, 5, 25, or 50 mg MACR/kg/day) and rabbits on GD 6 through 19 (0, 1, 3, or 5 mg MACR/kg/day). Maternal clinical status was monitored daily during treatment. At termination (GD 20, rats; GD 30, rabbits), confirmed-pregnant females (25-26 per group, rats; 17-22 per group, rabbits) were evaluated for clinical status and gestational outcome; each live fetus was examined for external, visceral, and skeletal malformations. In rats, no treatment-related maternal clinical signs or mortality were observed, nor was there any adverse effect on maternal body weight or food or water consumption. At necropsy, absolute, relative, and adjusted maternal liver weight was increased at the mid- and high-dose groups, an effect that may be indicative of induction of hepatic enzymes rather than toxicity. In the absence of any indication of maternal toxicity, the no-observed-adverse-effect level (NOAEL) for maternal toxicity in this study was >/=50 mg MACR/kg/day. The NOAEL for developmental toxicity in rats was also >/=50 mg MACR/kg/day. There was no effect of treatment on postimplantation loss, mean fetal body weight per litter, or morphological development. In rabbits, maternal mortality and clinical signs were not dose related. Maternal food consumption, body weight, and liver weight were not adversely affected by treatment. Thus, the maternal NOAEL was >/=5 mg MACR/kg/day. Maternal toxicity, including death, was observed >/=7.5 mg/kg/day in preliminary studies. The developmental NOAEL was also >/=5 mg MACR/kg/day. There was no adverse effect of treatment on postimplantation loss or fetal body weight. A significant decrease in the percentage male fetuses per litter was observed, although there was no effect on total live litter size, suggesting that the reduction in the ratio of live male fetuses in the high-dose group was not biologically significant. MACR had no adverse effect on morphological development. In summary, oral administration of MACR to rats and rabbits during organogenesis, at doses that did not cause persistent maternal toxicity (50 mg MACR/kg/day, rats; 5 mg MACR/kg/day, rabbits), also did not cause any adverse developmental effects.     

Comparison of a new triazole antifungal agent, Schering 56592, with itraconazole and amphotericin B for treatment of histoplasmosis in immunocompetent mice

A murine model of intratracheally induced histoplasmosis was used to evaluate a new triazole antifungal agent, Schering (SCH) 56592, for treatment of histoplasmosis. MICs were determined for SCH 56592, amphotericin B, and itraconazole by testing yeast-phase isolates from 20 patients by a macrobroth dilution method. The MICs at which 90% of the isolates are inhibited were for 0.019 microgram/ml for SCH 56592, 0.5 microgram/ml for amphotericin B, and < or = 0.019 microgram/ml for itraconazole. Survival studies were done on groups of 10 B6C3F1 mice with a lethal inoculum of 10(5). All mice receiving 5, 1, or 0.25 mg of SCH 56592 per kg of body weight per day, 2.5 mg of amphotericin B per kg every other day (qod), or 75 mg of itraconazole per kg per day survived to day 29. Only 44% of mice receiving 5 mg of itraconazole/kg/day survived to day 29. Fungal burden studies done in similar groups of mice with a sublethal inoculum of 10(4) showed a reduction in CFUs and Histoplasma antigen levels in lung and spleen tissue in animals treated with 2 mg of amphotericin B/kg qod, 1 mg of SCH 56592/kg/day, and 75 mg of itraconazole/kg/day, but not in those treated with lower doses of the study drugs (0.2 mg of amphotericin B/kg qod, 0.1 mg of SCH 56592/kg/day, or 10 mg of itraconazole/kg/day). Serum drug concentrations were measured 3 and 24 h after the last dose in mice (groups of five to seven mice), each treated for 7 days with SCH 56592 (10 and 1 mg/kg/day) and itraconazole (75 and 10 mg/kg/day). Mean levels measured by bioassay were as follows: SCH 56592, 10 mg/kg/day (2.15 micrograms/ml at 3 h and 0.35 microgram/ml at 24 h); SCH 56592, 1 mg/kg/day (0.54 microgram/ml at 3 h and none detected at 24 h); itraconazole, 75 mg/kg/day (22.53 micrograms/ml at 3 h and none detected at 24 h); itraconazole, 10 mg/kg/day (1.33 micrograms/ml at 3 h and none detected at 24 h). Confirmatory results were obtained by high-pressure liquid chromatography assay. These studies show SCH 56592 to be a promising candidate for studies of treatment of histoplasmosis in humans.     

Rapid tolerance to the depressive effects of diazepam on guinea pig motor control using divided doses

The effects of acute and chronic IP injections of diazepam on the guinea pig righting reflex latency (RRL) were measured using an automated measurement system known as a "tolerometer." Single IP injections of 2.0, 6.0, 18.0, and 20.0 mg/kg diazepam significantly increased the RRL compared to no injection (naive animals), diazepam vehicle injections, or 1.0 mg/kg diazepam injections. The effects of chronic IP injection schedules on the RRL were compared: 18 or 20 mg/kg in a single, once daily injection for 5 days; 6 mg/kg in a single, once daily injection for 5 days; and 6 mg/kg, three times a day, for 5 days. Neither 20, 18, nor 6 mg/kg/day for 5 days resulted in significant tolerance to the depressive effects of diazepam on the righting reflex. By contrast, when 6 mg/kg was administered three times a day for 5 days, tolerance developed by the third day of treatment. There were no differences between the three groups in the amount of exposure to the measurement apparatus or the testing situation. These results support the view that species like guinea pig and rat that metabolise diazepam rapidly, develop tolerance more quickly if diazepam is administered in divided doses or by continuous release; this may be because the duration of the occupation of CNS benzodiazepine recognition sites is a critical factor in the development of tolerance.     

Cloning of a thermostable ascorbate oxidase gene from Acremonium sp. HI-25 and modification of the azide sensitivity of the enzyme by site-directed mutagenesis

Concurrent abuse of cocaine and opioids is frequently observed clinically, and we have developed a model of "speedball" self-administration involving the simultaneous injection of cocaine and heroin combinations in rhesus monkeys (Mello et al. (1995) J Pharmacol Exp Ther 274:1325). In the present study, we evaluated the effects of buprenorphine (0.0075-0.75 mg/kg/day i.v.) and saline on speedball combinations of cocaine [0.001, 0.01 or 0.10 mg/kg/inj] and heroin [0.0001-0.032 mg/kg/inj]. We also examined the effects of buprenorphine (0.075 and 0.237 mg/kg/day i.v.) on self-administration of heroin alone (0.0001-0.01 mg/kg/inj). Drug and food (1-g banana pellets) self-administration were maintained on a second-order FR4 (VR16:S) schedule in four 1-hr sessions each day. Each buprenorphine or saline control treatment was evaluated for 10 consecutive days, and monkeys returned to base-line performance between each treatment condition. Buprenorphine (0.075-0.75 mg/kg/day) selectively reduced self-administration of speedball combinations of low-dose cocaine (0.001 mg/kg/inj) and heroin (0.001 or 0.0032 mg/kg/inj) (P < .05-.01), and buprenorphine (0.237 mg/kg/day) shifted dose-effect curves for speedball combinations of cocaine (0.001 mg/kg/inj) and heroin (0.0001-0.032 mg/kg/inj) downward (P < .05-.01) and approximately 1 log unit to the right. Buprenorphine treatment was less effective in decreasing responding maintained by speedball combinations of heroin and 0.01 and 0.10 mg/kg/inj cocaine. Buprenorphine treatment (0.075 and 0.237 mg/kg/day) also shifted the heroin dose-effect curve downward (P < .01-.001) and to the right. Both speedball and heroin self-administration were associated with dose-dependent decreases in food-maintained responding during saline control treatment. However, food-maintained responding was often higher than control levels during buprenorphine treatment (P < .05-.001), which suggests that buprenorphine antagonized the rate-decreasing effects of speedballs and of heroin. Buprenorphine's selective reduction of speedball and heroin self-administration is consistent with clinical treatment trials in opioid abusers and polydrug abusers. Thus, these primate models of speedball and heroin self-administration should be useful for preclinical evaluation of novel drug abuse treatment medications.     

Aminohydroxybutane bisphosphonate and clenbuterol prevent bone changes and retard muscle atrophy respectively in tail-suspended rats

Hind-limb unloading by tail suspension of rats, an established model of simulated microgravity, was used to examine the efficacy of aminohydroxybutane bisphosphonate (AHBuBP) and clenbuterol in preventing bone loss and muscle atrophy, respectively. Male Sprague-Dawley rats (299-372 g) were randomized into six groups of six: 1) unsuspended, saline, 2) unsuspended, saline, pair fed with group 3, 3) suspended, saline, 4) suspended, 0.03 mg/kg/day x 2 of AHBuBP, 5) suspended, 0.3 mg/kg/day x 2 of AHBuBP and 6) suspended, 0.3 mg/kg/day x 2 of AHBuBP + clenbuterol (0.5 mg/kg/day i.p. x 6, then 1 mg/kg/day i.p. x 6). Animals in groups 3 to 6 were tail suspended for 14 days from a system of double pulleys and allowed free mobility with their hind limbs unloaded. On days -2 and -1, before suspension on day 0, all rats received a single s.c. injection of either 2 ml/kg of normal saline (vehicle) or AHBuBP. All rats were tested for exercise tolerance before day -2 and on day 10, and grip strength before day -2 and on day 13. On day 14, the rats were euthanized and their humeri, tibias and femurs analyzed in vitro for bone density (by single-photon absorptiometry), strength and stiffness (by 3-point bending). Muscles were analyzed for weight, protein concentration and enzyme activity. Pair feeding had no effect other than on food consumption and body weight. AHBuBP caused a dose-dependent increase in bone density in humeri, tibias and femurs, even in tail-suspended rats, relative to control unsuspended animals, with no significant difference in bone strength or stiffness between AHBuBP groups and unsuspended animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Granulocyte colony-stimulating factor enhances bone marrow stem cell damage caused by repeated administration of cytotoxic agents

Despite the increasing use of cytokines to circumvent the acute dose-limiting myelotoxicity of cancer treatment, little is known about the combined effects of cytotoxic agents and cytokines on the primitive stem cells responsible for long-term hematopoiesis. In an experimental model, we administered cytotoxic agents that have variable effects on primitive stem cells in C57BL/6 (B6)-mice. Mice received six every-other-week doses of cyclophosphamide (CY, 84 mg/kg), VP-16 (24 mg/kg) + cisplatinum (2.4 mg/kg), carboplatinum (50 mg/kg), chlorambucil (12 mg/kg), BCNU (13.2 mg/kg), or TBI (80 cGy). Granulocyte colony-stimulating factor (G-CSF; 250 microg/kg/day) was administered subcutaneously twice daily on days 3 to 6 after each dose of the cytotoxic agent. Comparison with animals receiving the cytotoxic agent alone was made to investigate the effects of G-CSF on long-term hematopoiesis. Hematopoiesis was measured 20 weeks after the last dose of the cytotoxic agent by assessment of peripheral blood counts, marrow cellularity, progenitor cell content (colony-forming units-spleen; CFU-S), and primitive stem cell number (long-term repopulating ability and day 28 and day 35 cobblestone area-forming cell [CAFC] frequencies). Exposure to cytotoxic agents alone resulted in a significant decrease in primitive stem cells (as measured by repopulating units [RU] and day 28 and day 35 CAFC content) in animals given carboplatinum, chlorambucil, BCNU, and TBI, but not in animals treated with cyclophosphamide or VP-16 and cisplatinum. The addition of G-CSF resulted in a significant decrease in stem cell content when compared with no G-CSF administration in animals treated with chlorambucil, BCNU, or TBI. Thus, G-CSF administered after repeated exposure to cytotoxic agents, appeared to damage the primitive stem cell compartment when used in combination with agents known to damage primitive stem cells. These results, although obtained in an experimental model, should raise concerns for the indiscriminate use of G-CSF in the clinic.     

Modification of vancomycin nephrotoxicity by other antibiotics in rats

Vancomycin (VCM) was intravenously administered to rats for 14 days at doses of 150 mg/kg/day and 250 mg/kg/day alone or in combination with 1,000 mg/kg/day of latamoxef (LMOX), flomoxef (FMOX) or cefpirome (CPR) or 250 mg/kg/day of fosfomycin (FOM), and the influences of combined antibiotics on the VCM-induced renal damage were studied. The renal impairment caused by VCM alone was, morphologically, demonstrated mainly as regeneration of tubular epithelium: slight regeneration was observed in a half of rats administered 150 mg/kg/day and slight to extensive regeneration in all the rats administered 250 mg/kg/day. Clinical examinations found apparent increases in urinary LDH and MDH activities in rats administered 250 mg/kg/day, thus showing a good correlation with renal pathological changes. In addition, increase in kidney weight and increase in urinary NAG activity were noted, while changes in plasma urea-N and creatinine were mild, and gamma-GTP activity and protein in urine could not be used as a parameter of the renal impairment. The slight renal impairment as noted in rats administered VCM 150 mg/kg/day alone was not observed at all when LMOX or FMOX was administered concomitantly, and less pronounced even when FOM was administered concomitantly. When CPR was administered concomitantly, the changes were the same as those observed with VCM alone. The renal impairment in rats administered VCM 250 mg/kg/day was apparently less severe when combined with LMOX, FMOX and FOM than that in rats administered VCM alone, and this was supported by apparent reduction of clinical examination values as the parameter of VCM-induced nephrotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early treatment of acute graft-versus-host disease with high- or low-dose 6-methylprednisolone: a multicenter randomized trial from the Italian Group for Bone Marrow Transplantation

Ninety-five patients undergoing an allogeneic bone marrow transplant (BMT) and developing acute graft-versus-host disease (aGvHD) were randomized to receive low-dose intravenous 6-methylprednisolone (6MPred; 2 mg/kg /d; n = 47) or high-dose 6MPred (10 mg/kg/d; n = 48) for 5 days, with subsequent tapering doses. On day 5 patients not responding or progressing on low-dose 6MPred could be switched to high-dose 6MPred. All patients, aged 1 to 55 years, were recipients of unmanipulated BMT from HLA identical sibling donors. Patients were stratified at randomization for age (/= 20 years), disease (acute leukemia, chronic myeloid leukemia [CML], nonneoplastic disease), disease status (early/advanced), and GvHD prophylaxis (cyclosporin/cyclosporin + methotrexate). Primary endpoints were response to treatment and evolution of aGvHD to grade III-IV. Secondary endpoints were cytomegalovirus (CMV) infections, transplant-related mortality (TRM), and relapse. The median interval between BMT and treatment was 12 days (6 to 43). Results in the two groups (2 v 10 mg/kg) were as follows: response of aGvHD 68% versus 71% (P = .9), evolution to aGvHD grade III-IV 17% versus 20% (P = . 6), CMV infections 55% versus 60% (P = .7), 3-year actuarial TRM 28% versus 32% (P = .7), relapse 17% versus 7% (P = .1). The actuarial survival at 3 years was 63% versus 62% (P = .9) with a median follow up of 580 and 778 days. On day 5 of therapy, 26 patients assigned to low-dose (2 mg/kg) 6MPred were switched to a higher dose of 6MPred because of no response or progression. Their actuarial TRM was 46%, which is significantly higher than TRM of patients who responded on 2 mg/kg and continued with tapering doses (TRM = 16%, P = .007). In conclusion, early treatment of acute GvHD with 6MPred 10 mg/kg/d does not improve the response rate as compared with 2 mg/kg/d, nor does it prevent evolution to aGvHD grade III-IV. CMV infections, TRM, and survival were also comparable. A group of patients at high risk of TRM can be identified after 5 days of treatment with 6MPred 2 mg/kg and could be eligible for alternative forms of therapy.     

The role of mesolimbic dopamine in conditioned locomotion produced by amphetamine.

Daily administration of psychomotor stimulants in a distinctive environment can impart on the environment stimulantlike properties. Rats injected with amphetamine (0.75 mg/kg, sc) daily for 5 days exhibited a robust unconditioned locomotor response, measured in photocell cages, and showed a conditioned locomotor response when treated with saline on the 6th day. This conditioned locomotor response was found to be significantly attenuated by 6-hydroxydopamine (6-OHDA) lesions of the nucleus accumbens when the lesion was made either pre- or postconditioning. Similarly, although rats with 6-OHDA lesions of the nucleus accumbens exhibited a robust supersensitive unconditioned locomotor hyperactivity in response to apomorphine (0.1 mg/kg, sc), they did not show a conditioned response on the test day. Results suggest that the mesolimbic dopamine system may be responsible for both the unconditioned and conditioned locomotor responses to psychomotor stimulant drugs. Further, conditioned locomotion depends on a critical interaction between the physiological release of presynaptic dopamine and occupation of postsynaptic receptors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)