Adrenergic supersensitivity in Parkinsonians with orthostatic hypotension

The adrenergic status was studied through evaluation of platelet alpha 2-adrenoceptor number [( 3H]yohimbine binding sites), plasma catecholamine levels and blood pressure response to noradrenaline infusion in three groups of subjects (1) Parkinsonians with orthostatic hypotension; (2) Parkinsonians without orthostatic hypotension; and (3) control subjects. In Parkinsonians with orthostatic hypotension, systolic and diastolic blood pressures significantly (P less than 0.05) decreased from 144 +/- 9 and 76 +/- 6 mmHg in the lying position to 95 +/- 12 and 60 +/- 7 mmHg after 5 min standing. In these patients, noradrenaline plasma levels were significantly low (62 +/- 11 pg ml-1, (P less than 0.05) when compared with controls (219 +/- 13 pg ml-1) whereas no difference was noticed in Parkinsonians without orthostatic hypotension (195 +/- 14 pg ml-1). The noradrenaline dose required for a 25 mmHg increase in systolic blood pressure was significantly (P less than 0.01) lower in Parkinsonians with orthostatic hypotension (0.19 +/- 0.03 microgram kg-1) when compared with Parkinsonians without orthostatic hypotension (0.86 +/- 0.11 microgram kg-1) or with controls (0.68 +/- 0.1 microgram kg-1). Platelet alpha 2-adrenoceptor number was higher in Parkinsonians with orthostatic hypotension (313 +/- 52 fmol mg-1 protein) than in Parkinsonians without orthostatic hypotension (168 +/- 9 fmol mg-1 protein) or in controls (175 +/- 4 fmol mg-1 protein) with no change in Kd. This study demonstrates that in patients with Parkinson's disease, orthostatic hypotension is associated with an increase in both vascular sensitivity to noradrenaline and platelet alpha 2-adrenoceptor number.(ABSTRACT TRUNCATED AT 250 WORDS)     

Twelve‐month outcomes and predictors of very stable INR control in prevalent warfarin users

Summary. Background: For patients on warfarin therapy an international normalized ratio (INR) recall interval not exceeding 4 weeks has traditionally been recommended. For patients whose INR values are nearly always therapeutic, less frequent INR monitoring may be feasible. Objective: To identify patients with stable INRs (INR values exclusively within the INR range) and comparator patients (at least one INR outside the INR range), compare occurrences of thromboembolism, bleeding and death between groups, and identify independent predictors of stable INR control. Methods: The study was a retrospective, longitudinal cohort study using data extracted from electronic databases. Patient characteristics and risk factors were entered into multivariate logistic regression models to identify variables that independently predict stable INR status. Results: There were 533 stable and 2555 comparator patients. Bleeding and thromboembolic complications were significantly lower in stable vs. comparator patients (2.1% vs. 4.1% and 0.2% vs. 1.3%, respectively; P < 0.05). Independent predictors of stable INR control were age >70 years, male gender and the absence of heart failure. Stable patients were significantly less likely to have target INR ≥3.0 or chronic diseases. Conclusion: A group of patients with exclusively therapeutic INR values over 12 months is identifiable. In general, these patients are older, have a target INR <3.0, and do not have heart failure and/or other chronic diseases. Our findings suggest that many patients whose INR values remain within the therapeutic range over time could be safely treated with INR recall intervals >4 weeks.     

浅议《沈菊人医案》“气为血帅”理论的运用

医案是中医临床实践的真实记录，收录医家成功治疗案例的经验和心得，体现诊疗过程中理法方药的具体运用。文章通过清末名医沈菊人的3则医案，从气生血、行血、摄血浅谈"气为血帅"理论在临床上如何指导辨证用药。     

Screening for hepatitis B in chemotherapy patients: survey of current oncology practices

Background Hepatitis B virus (HBV) reactivation occurs in up to 78% of patients receiving cytotoxic chemotherapy for nonhepatic malignancies. Reactivation can lead to hepatic dysfunction, jaundice and fulminant hepatic failure. Current recommendations include screening patients at risk for HBV prior to immunosuppressive therapy and initiating antiviral prophylaxis in patients with chronic HBV. Aim To investigate current practice among oncologists regarding HBV screening and antiviral prophylaxis in candidates for chemotherapy. Methods A survey was sent to American Medical Association registered oncologists assessing demographics and HBV screening practices. Statistical analysis was performed using Fisher’s exact test. Results In all, 265 responses were received. Office‐based physicians were less likely to screen for HBV prior to chemotherapy (P < 0.001). Years in practice varied: 51% with <5 years, 29% with 5–15 years and 18% with >15 years, with no difference in screening practices between groups (P = N.S.). Responders screen for HBV as follows: never – 20%, only in the presence of abnormal liver biochemistries – 30%, risk factors or history of hepatitis – 38%. In patients with known HBV, 75% of oncologists refer to specialists, 7% initiate therapy, while 15% do not refer or initiate therapy, most of whom are in an office setting (P = 0.02). Conclusions Twenty per cent of oncologists never screen for HBV prior to initiating chemotherapy. Office‐based physicians were less likely to screen, treat or refer to a specialist prior to chemotherapy. Greater education regarding risk of HBV reactivation is needed for clinicians treating patients with immunosuppressive therapies. Aliment Pharmacol Ther 31 , 240–246     

EFFECT OF CLONIDINE ON ADRENAL MEDULLA CATECHOLAMINE LEVELS IN RATS

The effects of clonidine on adrenal medulla catecholamines levels were studied in normotensive rats. Intraperitoneal injections (50,100 micrograms/kg) of clonidine caused a dose-dependent decrease in adrenaline content of the gland. This effect was suppressed by denervation of the adrenal medulla, i.e. unilateral section of splanchnic fibers performed 5 days before. These results demonstrate that clonidine decreases the catecholamine content of the adrenal medulla only through a central action. They suggest that the adrenal medulla is involved in the hypotensive effect of clonidine.     

Right Ventricular Septal Pacing: A Comparative Study of Outflow Tract and Mid Ventricular Sites

Background: Prolonged right ventricle (RV) apical pacing is associated with left ventricle (LV) dysfunction due to dysynchronous ventricular activation and contraction. Alternative RV pacing sites with a narrower QRS compared to RV pacing might reflect a more physiological and synchronous LV activation. The purpose of this study was to compare the QRS morphology, duration, and suitability of RV outflow tract (RVOT) septal and mid‐RV septal pacing. Methods: Seventeen consecutive patients with indication for dual‐chamber pacing were enrolled in the study. Two standard 58‐cm active fixation leads were passed to the RV and positioned in the RVOT septum and mid‐RV septum using a commercially available septal stylet (model 4140, St. Jude Medical, St. Paul, MN, USA). QRS duration, morphology, and pacing parameters were compared at the two sites. The RV lead with less‐satisfactory electrical parameters was withdrawn and deployed in the right atrium. Results: Successful positioning of the pacing leads at the RVOT septum and mid‐RV septum was achieved in 15 patients (88.2%). There were no significant differences in the mean stimulation threshold, R‐wave sensing, and lead impedance between the two sites. The QRS duration in the RVOT septum was 151 ± 14 ms and in the mid‐RV septum 145 ± 13 ms (P = 0.150). Conclusions: This prospective observational study shows that septal pacing can be reliably achieved both in the RVOT and mid‐RV with active fixation leads using a specifically shaped stylet. There are no preferences in regard to acute lead performance or paced QRS duration with either position. (PACE 2010; 33:1169–1173)     

SERUM ZINC CONCENTRATIONS IN GROWING PREMATURE INFANTS

ABSTRACT. Serial serum zinc concentrations were measured in 31 relatively well, growing premature infants during the first 26 weeks of life. Zinc concentrations declined progressively from 17.9 μmol (1.17 mg/1) at birth (normal adult value) to 8.9 μmol (0.58 mg/1) at 6 weeks of age despite a zinc intake of greater than 13.7 μmol (900 μg)/kg/day after the second week of life. The serum zinc increased after 16 weeks of age to 10.7 μmol/dl (0.7 mg/1). No infant demonstrated clinical signs of zinc deficiency. This data may serve as a reference against which serum zinc concentrations in other premature infants may be compared in order to help define the deficiency state.     

Conversion of Atrial Fibrillation by the Experimental Antiarrhythmic Drug Tedisamil in Two Canine Models

INTRODUCTION: Tedisamil is an experimental bradycardic agent possessing action potential-prolonging effects. It has been proven effective in terminating ventricular arrhythmias in several animal models and atrial flutter in a conscious dog model. There are no reports to date evaluating tedisamil's efficacy in terminating atrial fibrillation (AF). METHODS AND RESULTS: Two different canine models of AF were used. One group of dogs (n = 6) was subjected to 28 days of chronic fibrillatory pacing at 50 Hz using an implantable neural stimulator. Sustained AF was achieved in all dogs within 14 days of initiating pacing. A second set of dogs (n = 5) had AF induced via bilateral vagal stimulation. Tedisamil 1 mg/kg was 100% effective in terminating AF in both models. Cardioversion was associated with a statistically significant prolongation of the fibrillatory cycle length immediately before return to normal sinus rhythm in both models. A dose-response trial was performed in the vagal AF group as well as in a second group of three dogs that underwent chronic fibrillatory pacing. The efficacy of tedisamil was dose dependent, with limited efficacy at 0.1 and 0.3 mg/kg intravenously in both models. Tedisamil was able to prevent reinduction of sustained AF 30 minutes after administration of 1 mg/kg in the chronic pacing model in all dogs. Side effects included minor hypersalivation in most dogs receiving the 1 mg/kg dose. No ventricular ectopy or arrhythmias were observed. CONCLUSION: Tedisamil is effective for conversion of sustained AF to normal sinus rhythm in two different models of AF.