Patterns and stability of cardiovascular responses to variations of the cold pressor test

Test-retest reliabilities and patterns of heart rate and blood pressure responses were examined using variations in the cold pressor test in 113 normotensive white college men. Comparisons were made of stimulus site (forehead vs. foot) and bodily posture (seated vs. supine) across four separate groups of men. The stability of cardiovascular responses was examined over a 2-week test-retest interval. Different cardiovascular response patterns emerged as a function of stimulation site and posture. Systolic and diastolic blood pressure increases were accompanied by bradycardia in the forehead cold pressor task but by tachycardia in the foot cold pressor task. Systolic blood pressure increases were larger for foot than for forehead stimulation. Heart rate increases were larger for supine than for seated men. Effects on response were independent of postural differences at baseline, and there were no stimulation site by posture interactions. The cardiovascular responses to stimulation did not attenuate across sessions in any experimental condition but were more reliable for foot than for forehead stimulation and for supine than for seated posture. Short-term stability for changes to the task approached that for baseline and task and was higher than has been reported elsewhere.     

EVIDENCE FOR INDEPENDENT REGULATION OF HUMAN ERYTHROCYTE AND ADIPOCYTE INSULIN RECEPTORS

Specific binding of [125I]-insulin was measured in erythrocytes and fat obtained at the time of mastectomy in twenty-three subjects. There was a significant negative correlation between the level of specific binding to fat and fasting insulin concentration (r=0.55, p less than 0.05, n=23) suggesting down-regulation of fat insulin level by insulin. Insulin binding to erythrocytes did not correlate with insulin nor was there any relationship between insulin binding to erythrocytes and fat from the same subject. Thus while the erythrocyte insulin receptor may be of interest in its own right, it may not be subject to the normal regulatory influences seen in classical insulin target tissues. Insulin binding to erythrocytes may therefore be invalid as a model to study down-regulation of insulin receptors.     

Paroxysmal A trial Fibrillation:

Classification of Atrial Fibrillation. Introduction: Clinical aspects of paroxysmal atrial fibrillation are heterogeneous. The attacks of atrial fibrillation may differ in their duration frequency and presence and severity of symptoms. Therefore, a proposal for a clinical classification of paroxysmal atrial fibrillation may be helpful. We tested a new classification system in a cohort of 51 consecutive hospitalized patients with paroxysmal atrial fibrillation. Methods and Results: Paroxysmal atrial fibrillation was subdivided into three classes. Class I included a first attack of symptomatic atrial fibrillation either with spontaneous termination (IA) or requiring cardioversion because of poor tolerance (IB). Class II included recurrent attacks in untreated patients within three subgroups: IIA with no symptoms, IIB with < 1 symptomatic attack per 3-month period, and IIC > with 1 symptomatic attack per 3-month period. Class III included recurrent atrial fibrillation unresponsive to one or more antiarrhythmic agents for prevention of recurrences. Class III also consisted of three subgroups: IIIA with no or mild symptoms, IIIB with < 1 symptomatic attack per 3-month period, and IIIC with > 1 symptomatic attack per 3-month period. The criteria for paroxysmal atrial fibrillation (episode > 2 minutes and < 7 days in duration) were fulfilled by 51 patients (29 men, 22 women; mean age 61 ± 14 years). Structural heart disease was present in 31 patients; the atrial fibrillation was idiopathic in 18 (35%). All 51 patients could be classified within the three classes and their subgroups: 14 patients (27%) in Class I, 13 (25%) in Class II, and 24 (47%) in Class III. The incidences of idiopathic atrial fibrillation were 21%, 30%, and 45% of the patients in Classes I, II, and III, respectively. Conclusions: Based on this new classification system, all hospitalized patients with paroxysmal atrial fibrillation could be classified. This classification may be useful to delineate better the clinical subgroups of patients with paroxysmal atrial fibrillation, to characterize better the patient population in future studies, and to improve treatment strategies.     

胸主动脉瘤外科治疗术式探讨

目的：探寻治疗胸主动脉瘤的新术式。方法：13例胸主动脉瘤病例。7例行单纯带膜血管内支架（Stent-graft）治疗，2例行单纯主动脉弓人造血管替换术，3例夹层破裂（De BakeyI）患者行象鼻手术加带膜血管内支架植入术，1例行胸腹主动脉替换术。结果：带膜血管内支架组5例成功，1例失败，1例术后死亡；5例手术病例均成功，恢复顺利，无并发症。结论：带膜血管内支架为治疗胸降主动脉瘤的一种有效可靠方法；象鼻手术结合带膜血管内支架是治疗De BakeyI型的新方式，可降低手术并发症及术后死亡率。     

Developmental Toxicity of PCB 126 (3,3',4,4',5-Pentachlorobiphenyl) in Nestling American Kestrels (Falco sparverius)

Planar PCB congeners are embryotoxic and teratogenic to birdsincluding American kestrels. The developmental toxicity of 3,3',4,4',5-pentachlorobiphenyl(PCB 126) was studied in the posthatching kestrel as a modelfor the eagle. Nestlings were dosed orally for 10 days with5 µl/g body weight of corn oil (controls) or the planarPCB 126 at concentrations of 50, 250, or 1000 ng/g body weight.Dosing with 50 ng/g of PCB 126 resulted in a hepatic concentrationof 156 ng/g wet weight, liver enlargement and mild coagulativenecrosis, over 10-fold increases in hepatic microsomal ethoxyresorufin-O-dealkylaseand benzyloxyresorufin-O-dealkylase, and approximately a 5-foldincrease in methoxyresorufin-O-dealkylase. At this dose, mildto moderate lymphoid depletion of the spleen was apparent, aswere decreased follicle size and content of the thyroid. At250 ng/g, concentration of PCB 126 in the liver was 380 ng/gwith increasing multifocal coagulative necrosis, decreased bonegrowth, decreased spleen weight with lymphocyte depletion ofthe spleen and bursa, and degenerative lesions of the thyroid.At 1000 ng/g, the liver concentration was 1098 ng/g, accompaniedby decreased bursa weight, decreased hepatic thiol concentration,and increased plasma enzyme activities (ALT, AST, and LDH-L)in addition to the previous effects. Highly significant positivecorrelations were noted between liver concentrations of PCB126 and the ratio of oxidized to reduced glutathone. These findingsindicate that nestling kestrels are more susceptible to PCB126 toxicity than adults, but less sensitive than embryos, andthat planar PCBs are of potential hazard to nestling birds.