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81.
BACKGROUND: The Na+ channel is voltage gated and characterized by three distinct states: closed, open, and inactivated. To identify the effects of halothane on the cardiac Na+ current (I(Na)) at various membrane potentials, the effects of 1.2 mM halothane at different holding potentials (V(H)) on I(Na) were examined in single, enzymatically isolated guinea pig ventricular myocytes. METHODS: The I(Na) was recorded using the whole-cell configuration of the patch-clamp technique. Currents were generated from resting V(H)s of -110, -80, or -65 mV. State-dependent block was characterized by monitoring frequency dependence, tonic block, and removal of inactivation by veratridine. RESULTS: Halothane produced significant (P < 0.05) V(H)-dependent depressions of peak I(Na) (mean +/- SEM): 24.4 +/- 4.1% (V(H) = -110 mV), 42.1 +/- 3.4% (V(H) = -80 mV), and 75.2 +/- 1.5% (V(H) = -65 mV). Recovery from inactivation was significantly increased when cells were held at -80 mV (control, tau = 6.0 +/- 0.3 ms; halothane, tau = 7.1 +/- 0.4 ms), but not at -110 mV. When using a V(H) of -80 mV, halothane exhibited a use-dependent block, with block of I(Na) increasing from 8.6 +/- 1.4% to 30.7 +/- 3.5% at test pulse rates of 2 and 11 Hz, respectively. Use-dependent inhibition was not apparent at V(H) of -110 mV. When inactivation of I(Na) was removed by exposure to 100 microM veratridine, no significant difference was observed in the depressant effect of halothane at both V(H)s: 26.6 +/- 4.5% (V(H) = -80 mV) and 26.4 +/- 5.6% (V(H) = -110 mV). CONCLUSIONS: The present findings indicate that the depressant action of halothane on cardiac I(Na) depends on the conformational state of the channel. As more channels are in the inactivated state, the more potent is the effect of halothane. Removal of channel inactivation by veratridine abolished the dependence of the halothane effect on V(H), but depression of the current was still evident. These results indicate a complex interaction between halothane and the various conformational states of the Na+ channel. 相似文献
82.
83.
PURPOSE: Transjugular intrahepatic portosystemic shunts (TIPS) have markedly simplified the care of patients with refractory variceal bleeding. Follow-up of liver biochemical profiles, however, has not been done in a prospective fashion. PATIENTS AND METHODS: Twenty-nine patients undergoing TIPS placement for refractory variceal bleeding underwent serial laboratory tests and assessment of encephalopathy to determine the effect of TIPS. Prothrombin time and aspartate aminotransferase, alanine aminotransferase, total bilirubin, alkaline phosphatase, serum albumin, serum creatinine, and venous ammonia levels were checked prior to the procedure, at the time of discharge, and at 3 weeks, 3 months, and 6 months following the procedure. RESULTS: There was no statistically significant change in any of the obtained laboratory values at up to 6 months of follow-up. The change in aspartate aminotransferase level approached but did not reach statistical significance at the time of discharge and was thought to be secondary to hepatocellular trauma associated with the procedure. New onset of encephalopathy occurred in 18.2% of patients and was easily controlled with medical therapy. CONCLUSIONS: TIPS does not appear to have a significant effect on the liver biochemical profile with short-term follow-up. Hepatic encephalopathy does occur, however, in a significant number of patients but is easily controlled with medical therapy. 相似文献
84.
JR Wagner MJ Merino HI Pass WM Linehan MM Walther 《Canadian Metallurgical Quarterly》1997,158(5):1688-1690
PURPOSE: Spontaneous regression of pulmonary metastases from renal cell carcinoma is a rare but well documented event. We present 2 recent cases that were radiographically consistent with pulmonary metastases from renal cell carcinoma but were pathologically shown to be pulmonary infarcts with no evidence of metastatic cells. Stable pulmonary infarcts can be misconstrued as metastatic disease in patients with renal cell carcinoma while resolving pulmonary infarcts may represent a subpopulation of patients with apparent spontaneous regression. Clinical implications of these findings are discussed. MATERIALS AND METHODS: Clinical and pathological data from 2 patients with large primary renal tumors, venous thrombi and lung masses were reviewed. Data from these cases, as well as pertinent urological and pathological literature, are presented. RESULTS: Although preoperative assessment was consistent with stage IV renal cell carcinoma, pathological examination of the lung masses in these patients showed no evidence of tumor cells. CONCLUSIONS: Pulmonary infarcts may mimic resolving or stable pulmonary metastasis in patients with renal cell carcinoma. Accurate clinical staging is crucial for the prognosis and treatment of renal cell carcinoma. Mistaking pulmonary infarcts for metastatic lesions can lead to inaccurate prognoses and inappropriate treatment. 相似文献
85.
H Kappauf WM Gallmeier PH Wünsch HO Mittelmeier J Birkmann G Büschel G Kaiser J Kraus 《Canadian Metallurgical Quarterly》1997,8(10):1031-1039
Spontaneous remission of cancer (SR) is defined as a complete or partial, temporary or permanent disappearance of all or at least some relevant parameters of a soundly diagnosed malignant disease without any medical treatment or with treatment that is considered inadequate to produce the resulting regression. We report the case of a 61-year-old man who presented with extensive metatastic disease five months after pneumonectomy for poorly differentiated large cell and polymorphic lung cancer. A vast metastatic tumour mass of the abdominal wall was confirmed histolologically and there was clinical and radiographic evidence of liver and lung metastases. Eight months later, the patient was operated on for a hernia, which had developed in the inguinal biopsy scar and the surgeon confirmed complete clinical SR of the abdominal wall metastases. Again five months later there was no longer any radiologic evidence of liver and lung metastases. Complete remission has persisted more than five years. Histology of the primary and of the abdominal metastases were reviewed by several independent pathologists. SR is an extremly rare event in lung cancer. This is the first documented case of clinically evident visceral metastases of a bronchiogenic adenocarcinoma developing after complete resection of the primary and then showing complete SR. The epidemiology of SR is reviewed and possible mechanisms involved in SR are discussed. 相似文献
86.
WM Feinberg ES Cornell SD Nightingale LA Pearce RP Tracy RG Hart EG Bovill 《Canadian Metallurgical Quarterly》1997,28(6):1101-1106
BACKGROUND AND PURPOSE: The prothrombin time (expressed as the international normalized ratio [INR]) is the standard method of monitoring warfarin therapy in patients with atrial fibrillation. Prothrombin activation fragment F1.2 provides an index of in vivo thrombin generation and might provide a better index of the effective intensity of anticoagulation. We examined the relationship between F1.2 and INR in patients with atrial fibrillation. METHODS: We measured INR and F1.2 levels in 846 patients with atrial fibrillation participating in the Stroke Prevention in Atrial Fibrillation III study. Two hundred nineteen (26%) were taking aspirin alone, 326 (39%) were taking adjusted-dose warfarin, and 301 (36%) were taking a low fixed dose of warfarin (1 to 3 mg) plus aspirin (combination therapy). F1.2 levels were measured with an enzyme-linked immunosorbent assay. RESULTS: Patients receiving adjusted-dose warfarin or combination therapy had significantly higher INR and significantly lower F1.2 values than those on aspirin alone (P < or = .0001 for each of the four comparisons). F1.2 values (nanomolar) were inversely correlated with INR (F1.2 = -0.1 + 2.3[1/INR]; R2 = .37; P < .0001; simple linear regression). However, significant variability remained. Among patients receiving warfarin, older patients had higher F1.2 values than younger patients after adjustment for INR intensity (P < .001) in the model. There was no difference in the relationship between F1.2 and INR between men and women. CONCLUSIONS: Increasing intensity of anticoagulation, as measured by the INR, is associated with decreasing thrombin generation as measured by the F1.2 level, but significant variability exists in this relationship. Older anticoagulated patients have higher F1.2 values than younger patients at equivalent INR values. The clinical significance of these differences is not clear. F1.2 measurement might provide information regarding anticoagulation intensity in addition to that reflected by the INR. 相似文献
87.
D Olde Weghuis ME Stoepker B de Leeuw E van den Berg RF Suijkerbuijk WM Molenaar B de Jong A Geurts van Kessel 《Canadian Metallurgical Quarterly》1994,9(4):288-291
In this case-control study, we investigated the role of Cryptosporidium in gastroenteritis in children < 6 years old. Six hundred fresh stool specimens were examined for various pathogenic parasites, bacteria, and rotaviruses. Wet-mount preparations, formaline-ether concentrations, and Sheather's floatation techniques were used to recover the parasite oocysts. Permanent stained slides using acid-fast stain and trichrome stains were prepared. Of 300 children with gastroenteritis symptoms, 20 (6.7%) had Cryptosporidium oocysts; seven of the 20 had concomitant infections so they were excluded from the counts. This infection rate is significantly different (Z = 2; p < 0.05) from that found in the control group (1.7%) of children who reported no symptoms. The most frequent symptoms reported beside diarrhea were abdominal pain, cramps, anorexia, nausea, vomiting, and fatigue. Contaminated drinking water is suspected to be the source of infection; other possible factors are discussed. 相似文献
88.
H Tsukamoto Y Hamada D Wu RJ Boado WM Pardridge 《Canadian Metallurgical Quarterly》1998,58(1-2):170-177
Visually identified and electrophysiologically characterized sympathetic preganglionic neurons (SPNs) were recorded using the whole-cell voltage clamp technique in slices of neonatal rat spinal cord. Monosynaptic excitatory postsynaptic currents (EPSCs) were evoked by electrical stimulation of the nucleus intercalatus in the presence of strychnine (5 microM) and bicuculline (10 microM). These EPSCs were abolished by the antagonist of AMPA-type glutamate receptors, 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX; 10 microM). Bath applied noradrenaline (NA; 0.5-50 microM) dose-dependently and reversibly decreased by up to around 60% the amplitude of the EPSC, without affecting the holding current. The EPSC depression by NA was not accompanied by a change in EPSC reversal potential (around +5 mV), nor were inward currents generated by pressure application of glutamate affected by NA application. A comparable degree of EPSC depression was also seen with the alpha2-adrenoceptor agonist clonidine (5 microM), and the alpha2A-agonist oxymetazoline (5 microM), while the alpha1-agonist phenylephrine (100 microM) caused only a 22% depression. The EPSC depression caused by NA (10 microM) was completely antagonized by either the alpha-antagonist phentolamine (10 microM) or the alpha2-antagonist idazoxan (2 microM). Conversely, the beta-adrenoceptor antagonist popranolol (5 microM), and the alpha1-, alpha2B- and alpha2C-antagonist prazosin (2 microM) were without effect. These results indicate that activation of presynaptic alpha2A-adrenoceptors on inputs to SPNs decreases glutamate release. 相似文献
89.
A Martin M State GM Anderson WM Kaye JM Hanchett CW McConaha WG North JF Leckman 《Canadian Metallurgical Quarterly》1998,44(12):1349-1352
BACKGROUND: Prader-Willi syndrome (PWS) is a genetic disorder characterized by mental retardation, appetite dysregulation, and a high risk for obsessive-compulsive disorder (OCD). Microscopic abnormalities of the hypothalamus have been described in PWS, and oxytocin has been implicated in both appetite regulation and OCD. METHODS: Oxytocin and arginine vasopressin (AVP) were measured in the cerebrospinal fluid of 5 subjects with PWS (2 male, 3 female) and in 6 normal control subjects (all female). RESULTS: CSF oxytocin was elevated in PWS (9.2 +/- 3.9 pmol/L) as compared to normal control subjects (5.1 +/- 0.9 pmol/L, p = 0.045), a finding that was more significant when excluding male subjects from analysis (p = 0.02). AVP was not significantly different between the groups as a whole. CONCLUSIONS: These data provide further evidence for hypothalamic and oxytocinergic dysfunction in PWS. The associations between oxytocin, appetite regulation, and obsessive compulsive symptomatology in PWS warrant further investigation. 相似文献
90.
ME Eremeeva WM Ching Y Wu DJ Silverman GA Dasch 《Canadian Metallurgical Quarterly》1998,167(2):229-237
Promyelocytic leukemia HL-60 cells promoted by PMA to differentiate along the monocyte pathway adhere to tissue culture plates. To explore the regulation of adhesion molecules in cells promoted to differentiate, the expression and secretion of osteopontin (OPN) and expression of associated cell surface receptors, CD44 and integrin subunits alpha(v), beta3, beta1, were examined. Results were as follows: 1) PMA induced OPN mRNA and OPN secretion into media; 2) untreated cells expressed beta1 and CD44 mRNA, and PMA induced alpha(v), and beta3 mRNA and increased beta1 and CD44 mRNA expression; 3) PMA increased levels of alpha(v), beta3, beta1 and CD44 protein on the cell surface; and 4) retinoic acid, which promotes granulocytic differentiation of HL-60 cells, did not affect OPN, alpha(v), beta3, beta1, or CD44 mRNA or protein expression. These data suggest that induction of OPN and associated receptors may play a role during monocytic differentiation of HL-60 cells. 相似文献