Total and regional myocardial blood flow in aortic regurgitation.

Total, phasic, and regional flow were studied in 12 open-chest dogs with aortic regurgitation. An adjustable catheter device was used to produce aortic regurgitation. Four differently labeled 7 to 9μ microspheres were injected into the left atrium during control, mild (5 to 25 per cent), moderate (25 to 50 per cent), and severe (50 to 80 per cent) regurgitation. Aortic regurgitation (AR) and the ratio of diastolic coronary blood flow to systolic coronary blood flow ($\text{DIAS}\text{SYS}$ RATIO) were measured from the electromagnetic flow tracings. The simultaneous left ventricular and aortic pressures were used to calculate $\text{DPTI}\text{SPTI}$ (diastolic pressure time index to systolic time index). Myocardial flow, flow to major subgroups, and endocardial/epicardial ratios were determined from radioisotope analysis of the left ventricle.Mean absolute control values and mean changes of key variables from control were:

3.

	Control	Mild AR	Mod AR	Severe AR
Heart rate (beats/min.)	163.42	?5.00	?4.831	?8.56
$\text{DPTI}\text{SPTI}$	1.18	?0.121	?0.241	?0.561
Dias/Sys ratio	4.23	?0.28	?1.641	?3.311
Myo. flow (ml./100g./min.)	99.90	?5.63	11.18	21.63
Endocardium (ml./100 g./min.)	97.27	?5.28	10.26	7.39
Epicardium (ml./100 g./min.)	100.15	?7.38	7.88	21.58
$\text{ENDO}\text{EPI}$ ratio	0.99	0.01	0.01	?0.11

1

Denotes significant change from control state (P = 0.05).

The phasic coronary blood flow results in this study are similar to those reported in chronic, intact anesthetized dogs; when the degree of aortic regurgitation increased, there was a significant decrease in diastolic coronary blood flow with an increase in systolic coronary blood flow. Not previously reported are the changes in the distribution of myocardial perfusion. Total myocardial flow increased slightly. There were minimal changes in blood flow to the endocardium which resulted in a slight decrease in the $\text{ENDO}\text{EPI}$ ratio and a decrease in the per cent of flow to the endocardium. These results indicate that, although acute aortic regurgitation produces significant changes in phasic coronary flow, there are much smaller effects on total and regional myocardial blood flow.     

Giant cell (cranial) arteritis: a clinical review

Giant cell arteritis is a disease of the elderly which is more common than previously recognized. It is important to be aware of this condition because treatment effectively relieves symptoms and prevents serious complications. The disease is suggested when an elderly patient complains of constitutional symptoms, headache, jaw claudication, or the musculoskeletal manifestations of polymyalgia rheumatica. Abnormalities in temporal arteries or other cranial arteries, or evidence of large vessel involvement may be detected by physical examination. A markedly elevated sedimentation rate in association with other clinical features of the disease strongly suggests giant cell arteritis, but a biopsy should be performed to confirm the diagnosis. Corticosteroid therapy should be started promptly in high doses in order to prevent blindness. Prolonged treatment with lower dose corticosteroids is generally necessary for up to 1 to 2 years, and sometimes longer, for continued symptomatic relief. Long-term follow-up of treated patients has demonstrated no detectable effect on survivorship.     

Placental transfer of aspartate and its metabolites in the primate.

The placental transfer of aspartate was tested in pregnant monkeys infused maternally with sodium aspartate. In five animals infused at 100 mg/kg/hr, maternal plasma aspartate levels increased from 0.36 ± 0.19 to 80.2 ± 11.5 μmole/dl (mean ± SD). However, fetal plasma aspartate levels increased only slightly from 0.42 ± 0.31 to 0.98 ± 0.24 μmole/dl (p = 0.02). Erythrocyte aspartate levels were unchanged in both fetal and maternal circulation. In two animals infused at 200 mg/kg/hr, maternal plasma aspartate levels increased from 0.28 and 0.31 μmole/dl to values of 141 and 237 μmole/dl, respectively. This increase produced a significant (p = 0.001) increase in fetal plasma aspartate levels from 0.53 and 0.67 to 3.3 and 4.5 μmole/dl, respectively. Maternal plasma aspartate levels in two animals infused at 400 mg/kg/hr increased from 0.5 and 0.7 μmole/dl to 400 and 750 μmole/dl, respectively, at the end of the infusion. Fetal plasma aspartate levels increased from 0.21 and 0.25 μmole/dl to 60 and 92 μmole/dl, respectively. Maternal aspartate infusion at each level increased maternal, but not fetal, plasma taurine levels. The increase in maternal taurine levels was not in proportion to the dose of aspartate infused. Aspartate metabolites, glucose, and lactate were readily transferred across the placenta. The data indicate that aspartate, like glutamate but unlike most amino acids, is not concentrated toward the fetal circulation in the pregnant primate, and suggest that a barrier to aspartate transfer exists unless maternal plasma levels are grossly elevated.     

What did we learn from the Shanghai hepatitis A epidemic?

A major outbreak of hepatitis A (HAV), associated with consumption of raw clams, occurred in Shanghai, China in 1988. Over 300 000 cases were reported, of which 47 (0.015%) were fatal. An elevated mortality rate was observed in hepatitis B surface antigen (HBsAg)-positive patients (0.05%). The majority of these patients were also hepatitis B e antigen (HBeAg)-positive, indicating active liver disease and high viral replication rates. The increased mortality in hepatitis B virus (HBV)/HAV coinfected individuals is hypothesized to be the result of T-cell-mediated destruction of HBV-infected hepatocytes, enhanced by acute HAV infection. Following recovery from HAV there is an increase in HBV expression and activated cytotoxic cells and subsequent cytolysis. Patients with chronic HBV infection are clearly at considerable risk of severe disease and increased mortality in the event of HAV infection. The period of greatest risk is during the immunoeliminative phase of HBV infection, which generally occurs in early adulthood. With the prevalence of HBV approaching 10% in this group, there is a clear opportunity for benefit from vaccination.     

Effects of the volume conductor on the apparent orientation of a known cardiac dipole

The surface electrocardiogram (EKG) is dependent on two major factors: the cardiac generator and the volume conductor. This investigation assessed the effects of the volume conductor in man on the apparent orientation of a simulated cardiac dipole. The apparent orientation of the dipole was calculated from measured surface potentials from about 60 locations on the body of five patients with implanted cardiac pacemakers. The real orientation of the dipole (an implanted pacemaker) was determined radiographically. The effects of both inhomogeneity and boundary characteristics of the volume conductor on the apparent orientation of the dipole were assessed using a new inverse algorithm. The difference between the orientation of the real and the calculated dipoles averaged 30 degrees (range 15 degrees--40 degrees) when the torso was assumed to be an infinite-homogeneous volume conductor. When the configuration of the torso was accounted for, however, the difference between the orientation of the real and calculated dipoles was reduced to 9 degrees (range 5 degrees--13 degrees). Thus, by taking into account the geometry of the torso and neglecting the inhomogeneities in the volume conductor, it is possible to calculate the orientation of a dipole in the cardiac region with an accuracy of about 9 degrees. It is reasonable to assume that the orientation of real activation wave fronts from localized areas of the heart could be calculated with a similar degree of accuracy.     

A search for heterogeneity in insulin dependent diabetes mellitus (IDDM): HLA and autoimmune studies in simplex, multiplex and multigenerational families

HLA antigens (A, B, C and DR loci), serum islet cell antibodies, thyrogastric antibodies, and insulin antibodies were studied in 77 families (25 simplex, 42 multiplex, and 10 multigenerational). In order to test for intrafamilial constancy and intergroup variation, we compared simplex with multiplex families, HLA identical and non identical siblings within families, as well as groups of families characterized by different DR alleles (DR3, DR4, and DR3/DR4) for various immunologic and clinical characteristics. These comparisons did not reveal all the distinct subgroups suggested by different cross-sectional population studies, but did provide evidence for a compound form having an aggregation of different high risk alleles. This study suggests that in many cases (and possibly especially in families with multiple affected individuals), there are several different genetic influences leading to IDDM.     

Some unusual features of gouty arthritis in females

Gouty arthritis in females is relatively infrequent, although the sex ratio may be somewhat altered in different races. A positive family history is relatively prevalent among females whose onset of gout is premenopausal. In those patients with a postmenopausal onset, the incidence of diuretic-associated gout is high. The bimodal distribution of serum urate might be related to some variance of genetic transmission in female gout.Hypertension and coronary heart disease are common coexisting conditions, as is true of gouty arthritis in males. Chronic urinary tract infection dating from previous pregnancies is a frequent complication. The relative prevalence of proteinuria and diminished renal function leads to increased hyperuricemia, with a tendency to a low urinary uric acid output. This explains in part the higher incidence of extensive tophaceous deposition but lower incidence of renal calculi. Diuretics are associated with a higher urine pH, likewise, they reduce the urinary uric acid excretion. This also may contribute to the lower incidence of renal calculi.There may be some statistical support for the low fertility rate among the gouty females. Only two females became pregnant after the onset of gouty arthritis. All other pregnancies occurred before the onset of arthritis. Even then, abnormal pregnancies were relatively frequent. Some hormonal malfunction among the gouty females cannot be discounted.Both renal calculi and tophi are frequent in female gout associated with blood dyscrasias. They may manifest early, preceding the first attack of acute gouty arthritis. In both the male and female secondary gout, the primary underlying disease governs the uric acid metabolism and the clinical symptomatology of gout. The predominant role in pathogenesis is the excessive rate of uric acid production, and its disposal is governed by the different stages of the underlying disease and the treatment. Thus, secondary gout in females appears to be somewhat different from primary gout in females, but not different from secondary gout in males.     

上海市不同人群人芽囊原虫感染调查

目的了解上海市不同人群人芽囊原虫感染情况。方法在上海市6个区收集居民新鲜粪便,采用Ringer溶液37℃恒温条件下培养人芽囊原虫,计算人芽囊原虫感染率。结果检查居民2 984人,人芽囊原虫阳性者88人,感染率2.95%。上海市各区人群感染率间差异无统计学意义(χ~2=9.90,P>0.05);青浦区男性感染率为5.56%,女性感染率1.57%,差异有统计学意义(χ~2=5.38,P<0.05),其他5个区男、女性感染率差异无统计学意义(χ~2=0.08～0.54,P均>0.05);农民感染率为6.87%,与其他职业人群比较差异有统计学意义(χ~2=18.57,P<0.05)。结论上海市人群对人芽囊原虫普遍易感,以农民感染率最高。体外培养法敏感性较高.可用于人芽囊原虫感染的流行病学调查。     

高通量测序技术在湖南省郴州市苏仙、北湖两区11212例孕妇地中海贫血基因筛查中的应用

目的:了解湖南省郴州市苏仙、北湖两区孕妇地中海贫血(简称地贫)携带率、基因突变频率及构成比。方法:采用高通量测序技术对11212例样本进行地贫基因分析。结果:检出地贫患者938例,其中α-地贫618例,β-地贫268例,异常血红蛋白29例,αβ-复合地贫23例,检出率分别为5.51%2.39%、0.26%、0.21%。α-地贫基因突变以--^SEA/αα(40.29%)及-α^3.7/αα(37.7%)为主,β-地贫以β^41-42M/β^N(24.26%)及β^654M/β^N(23.88%)为主。罕见型α、β地贫基因的检出率分别为0.19%(21/11212)、0.53%(59/11212)。结论:郴州市苏仙、北湖两区孕妇地贫基因携带率为8.37%,基因型复杂。高通量测序技术能有效地检出罕见地贫基因及新的基因突变。     

Termination of recurrent supraventricular tachycardia by right ventricular endocardial pacing but not by left ventricular epicardial pacing

Externally controlled ventricular pacing was employed in a patient with recurrent disabling supraventricular tachycardia and frequent sinus pauses between attacks of tachyarrhythmia. A permanent transthoracic demand pacemaker was inserted after electrophysiologic study demonstrated the effectiveness of ventricular stimulation in terminating induced supraventricular tachycardia. Subsequently, spontaneous recurrences of tachyarrhythmia failed to respond to fixed rate left ventricular stimulation accomplished by placing a magnet externally over the pacemaker pack. During an induced supraventricular tachycardia, repeat electrophysiologic study demonstrated that paced left ventricular beats failed to invade the A-V junctional area before it was depolarized previously by the corresponding tachycardia beat. Right ventricular stimulation from a transvenous pacemaker could depolarize the site of the reentrant circuit and terminate an induced supraventricular tachycardia. The addition of propranolol increased the ease by which spontaneous attacks of tachyarrhythmia could be terminated by right ventricular endocardial pacing.