Search PubMed⌕ Search

Biomedical subjects

A Schork

Publications and source records attributed to A Schork.

51 records · Page 3Linked to original sources
PubMed1987

[Imaging of aortocoronary bypasses with intravenous digital subtraction angiography].

We examined 24 patients with 52 coronary bypass grafts, an average of 18 months after their respective operations. During the course of 1 week, a coronary angiography and a digital subtraction angiography (DSA) incorporating an intravenous injection of contrast medium were performed. Conventional coronary angiograms showed 40 bypasses as being open, ten as being occluded, and two could not be displayed at all. With the aid of digital angiography, 50 out of 52 bypasses could be classified as either open or occluded. In 44 out of 52 bypasses, DSA and coronary angiogram results were identical. Using DSA, three out of ten angiographically occluded bypasses were falsely diagnosed as being open and three out of 40 open bypasses as occluded. Two bypasses could not be interpreted due to poor picture quality. In the diagnosis "open bypass" the degree of both sensitivity and specificity subsequently amounted to 92.5%, and 70% in the diagnosis "occluded bypass". The distal part of the bypasses, as well as the proximal and distal part of the anastomoses, could not be evaluated for the most part. Furthermore, on account of the comparatively inferior quality of the pictures, detection of bypass stenosis is not reliable using digital subtraction angiography. Intravenous digital subtraction angiography may therefore serve as a screening method in the evaluation of coronary bypass grafts.

Coronary Angiography↗
PubMed1986

Severe hypoglycemia during pregnancy: its frequency and predisposing factors in diabetic women.

Severe hypoglycemic episodes, as defined as altered consciousness to the extent that self treatment is impossible, were sought prospectively in pregnant diabetic women. One or more episodes were found in none of 21 gestational onset, insulin-requiring women during their 28 pregnancies but were present in 19 (33%) of the 57 already insulin dependent (Type 1) women during 26 (36%) of their 72 pregnancies. The most common predisposing factors included strict glucose control, anorexia, early morning hours (1200-0900), lack of an adrenergic response and time shortly before the next anticipated meal.

Adult↗
PubMed1986

Protective effects of N-2-mercaptopropionyl glycine against myocardial reperfusion injury after neutrophil depletion in the dog: evidence for the role of intracellular-derived free radicals.

Reperfusion of the previously ischemic myocardium is associated with the production of oxygen free radicals and their metabolites, which contribute to the ultimate extent of irreversible myocardial injury. The relative importance of polymorphonuclear leukocytes vs intracellular-derived oxygen metabolites has remained uncertain. We evaluated the effectiveness of a free-radical scavenger, N-2-mercaptopropionyl glycine (MPG), in limiting infarct size after ischemia/reperfusion in dogs that were depleted of neutrophils with specific antisera. Twenty-four urethane-anesthetized open-chest dogs were subjected to 90 min of ischemia by occlusion of the left circumflex coronary artery followed by 6 hr of reperfusion. Dogs were randomly assigned to receive nonimmune serum, neutrophil antiserum, or neutrophil antiserum plus MPG (20 mg/kg intra-atrially 15 min before reperfusion was initiated and for 45 min after reperfusion). Infarct size, as a percent of the area at risk, was reduced by 33% in the neutrophil antiserum group as compared with the nonimmune group (30.7 +/- 2.7% vs 45.6 +/- 3.7%, p less than .01). The combined administration of neutrophil antiserum plus MPG reduced the size of infarction by 63% of the area at risk compared with that in the nonimmune group (17.0 +/- 2.7% vs 45.6 +/- 3.7%, p less than .01). The reduction in infarct size with neutrophil antiserum plus MPG was significantly greater than that with the neutrophil antiserum alone (p less than .01). The areas at risk did not differ among the groups. Myocardial protection could not be explained on the basis of hemodynamic differences. The observation that MPG enhances the protective effects of neutrophil depletion suggests that both extramyocardial- and intramyocardial-derived oxygen free radicals contribute significantly to reperfusion-induced myocardial injury.

Amino Acids, Sulfur↗
PubMed1985

Changes in insulin therapy during pregnancy.

Care of the diabetic pregnant woman requires a proper understanding of anticipated changes in insulin therapy as a guide for establishing and maintaining strict glucose control. Changes in daily insulin doses were reviewed for 58 pregnancies of 50 insulin-dependent women who were followed for 26 +/- 3 weeks (mean +/- 1 SD) before delivery. By late gestation, insulin was administered on two or three occasions each day using a combination of regular--and intermediate--acting preparations in 55 (95%) pregnancies. Regardless of the metabolic control and duration of diabetes, averaged daily insulin requirements increased twofold from earlier in pregnancy. Following initial hospitalization, insulin requirements often decreased before increasing almost linearly between 2 and 9 months gestation. Fluctuations in insulin requirements were greatest during the last trimester. Insulin demand dropped precipitously after delivery and was two-thirds the averaged prepregnancy insulin dose or one-third the dose at 9 months gestation by the third postpartum day. The total average insulin dose was the same as that before pregnancy by the end of the first postpartum week. Explanations for these changes in prescribing insulin are described.

Diabetes Mellitus, Type 1↗
PubMed1984

The effect of dobutamine on exercise performance in patients with symptomatic ischemic heart disease.

The effect of dobutamine on exercise performance was assessed in 20 patients with ischemic heart disease (CAD) and a positive stress test. These patients had a wide range of resting left ventricular ejection fraction (range 22% to 69%, mean 42%). Each patient entered a double-blind crossover study in which two identical exercise radionuclide ventriculograms were performed in patients on dobutamine, 5 micrograms/kg/min intravenously, or placebo. Dobutamine increased resting left ventricular ejection fraction. Although ejection fraction fell with dobutamine during submaximal exercise, it remained higher than with placebo. At peak exercise, ejection fraction fell to the same level on dobutamine as with placebo. Dobutamine diminished exercise time and time to ischemia while peak pressure-rate product was unchanged. Four of 20 patients developed complex ventricular premature beats, all while on dobutamine. Although useful when administered to resting patients with acute left ventricular failure, dobutamine's effects may be deleterious in exercising patients with chronic ischemic heart disease.

Adult↗
PubMed1984

Long-term prognosis (15 to 26 years) after repair of tetralogy of Fallot: I. Survival and symptomatic status.

One hundred eighty-two patients with tetralogy of Fallot repaired before or during 1967 were studied by interview, physical examination, and noninvasive testing. Twenty were excluded from the final analysis because review of cineangiograms and operative reports disclosed that they had had double-chambered right ventricle rather than tetralogy of Fallot. On follow-up ranging from 15 to 26 years (mean, 20.2 years), there were 86 patients in New York Heart Association Functional Class I, 53 in Class II, 5 in Class III, and none in Class IV. There were 9 late deaths. Functional classification was not ascertained in the remaining 9 patients. Cumulative survival at 25 years postoperatively was 94.4%. There was no significant relationship between survival and year of operation, age at operation, sex, or presence of a prior shunt. The 9 late deaths occurred between 6 and 23 years after operation and were due to late-onset complete heart block in 2 patients, congestive failure in 4, suicide in 1, accident in 1, and an unknown cause in 1. We conclude that long-term survival after repair of tetralogy of Fallot is excellent and not influenced by prior shunt.

Adolescent↗
PubMed1983

Metallothionein and occupational exposure to cadmium.

The relationship between metallothionein (MT), chronic exposure to cadmium (Cd), and renal function was investigated in 53 men who were occupationally exposed to Cd. The aim was to determine if MT is a potential biological monitor for chronic exposure to Cd which would be useful for preventing Cd nephropathy. In this study MT excretion, serum MT, and serum creatinine concentrations were significantly higher in subjects with abnormal renal function who had been exposed to Cd. MT excretion was also linearly related on an individual basis to protein excretion, beta 2-microglobulin (beta 2-M) excretion, and cumulative time weighted exposure (dose). MT excretion was also a better predictor of dose than either beta 2-M excretion or Cd excretion. The findings suggest that MT is a potential biological monitor for chronic Cd exposure that would be useful for preventing Cd-induced nephropathy. Further studies of non-specific nephropathies and MT are needed to determine if MT is a specific indicator of proximal tubule function secondary to chronic exposure to Cd.

Adult↗
PubMed1983

Role of the autonomic nervous system in the release of rat submandibular gland kallikrein into the circulation.

We have previously demonstrated that the rat submandibular gland releases immunoreactive kallikrein into the circulation. To study the role of the autonomic nervous system in this release, submandibular gland blood flow and kallikrein concentration in peripheral arterial and venous blood from the gland were measured and secretion rates calculated before and after parasympathetic and sympathetic nerve stimulation (8V, 2 msec, 10 Hz) for 1 minute. Immunoreactive kallikrein in plasma was measured by radioimmunoassay, and timed collections of venous outflow were used to measure blood flow. During basal conditions, the unstimulated submandibular gland of the rat released immunoreactive kallikrein into blood at the rate of 0.92 +/- 0.07 ng/min. Parasympathetic stimulation increased blood flow 4-fold (before, 68.5 +/- 8.3 microliters/min; after, 253.5 +/- 76.2; P less than 0.05) without significantly changing immunoreactive kallikrein secretion rate. Sympathetic stimulation produced an 11-fold increase in blood flow (before, 64.9 +/- 9.3 microliters/min; after, 709.6 +/- 97.5; P less than 0.05) and a 57-fold increase in immunoreactive kallikrein secretion rate from the gland (before, 1.05 +/- 0.25 ng/min; after, 59.8 +/- 18.6; P less than 0.05). Sympathetic stimulation also produced a 4-fold increase in the concentration of immunoreactive glandular kallikrein in arterial plasma (before, 15.2 +/- 1.1 ng/ml; after, 56.2 +/- 12.9; P less than 0.05). Pretreatment with phentolamine (1 mg/kg) or prazosin (0.2 mg/kg) blocked the increase in kallikrein secretion rate produced by sympathetic stimulation. These results indicate that the sympathetic nervous system, through activation of alpha 1-adrenoreceptors, controls kallikrein secretion from the submandibular gland into the circulation. Released kallikrein may be responsible for the reactive vasodilation observed in the rat submandibular gland after sympathetic stimulation.

Adrenergic alpha-Antagonists↗
PubMed1975

Papaverine: its effects on cyclic AMP in vitro and psoriasis in vivo.

Psoriatic epidermis shows excessive cell proliferation, incomplete morphogenesis, and glycogen accumulation. These three features may result from coordinate misregulation by the previously reported abnormal lesional ratio of cyclic AMP/cyclic GMP. If so, it is possible that psoriasis might improve by topical application of an agent known to alter cellular levels of cyclic nucleotides. In the present study papaverine (3.0 x 10-4 m) produced a 210percent increase (.02 smaller than p smaller than .05) in epidermal cyclic AMP levels in vitro. Therefore, 1 percent papaverine cream (approximately 2.7 x 10-2m papaverine) was chosen to establish whether a cyclic AMP elevating agent could improve a soriatic lesion. A double-blind comparison of 1 percent papaverine cream versus cream alone was conducted on matched lesions in 45 patients. Of those patients showing differential improvement (i.e., only one lesion of the pair improved), 81 percent (p=0.011) of those showing a response in the center of the lesion and 77 percent (p=0.046) of those improving at the edge had applied papaverine. Although no attempts were made to develop a papaverine formulation with immediate therapeutic utility, the numerically significant papaverine results suggest future therapeutic developments.

Animals↗
PubMed1975

Role of renin in the pathogenesis of renal hypertension.

To test the hypothesis that renin is circulating in pressor amounts in renal hypertension, two-kidney Goldblatt hypertension was produced in rats. After hypertension had been present for a variable period of time (4 to 21 days), the ischemic kidney was removed, and an infusion of rat renin was started immediately to replace the endogenous renin that the ischemic kidney had been releasing. Since the amount of renin released by the clipped kidney was not known, the amount infused was regulated by a feedback mechanism set to keep the mean blood pressure at the same level as before ipsilateral nephrectomy. Hypertension remission was therefore prevented by this procedure. The PRA at the end of the renin infusion was similar to that prior to the ipsilateral nephrectomy. This finding indicates that the levels of the PRA circulating in renal hypertension are within the pressor range, thus supporting the hypothesis that renin plays a role in the pathogenesis of the acute or semiacute phase of renal hypertension. However, the participation of other factors cannot be ruled out since no correlation was found between PRA and blood pressure.

Animals↗
PubMedDate not supplied

Recruitment procedures and their impact on the prevalence of dementia. Results from the Leipzig Longitudinal Study of the Aged (LEILA75+).

Recruitment procedures may exert a considerable influence on the outcome of health surveys in the elderly. Their impact on the prevalence of dementia will be measured in an epidemiological field study in a sample of 1,692 randomly selected individuals (75+). Face-to-face interviews were conducted using SIDAM (structured interview for the diagnosis of dementia of Alzheimer type, multi-infarct dementia and dementias of other etiology according to ICD-10 and DSM-III-R). Furthermore, proxy interviews were performed with relatives of fragile and functionally dependent individuals. Considering face- to-face interviews of community-dwelling individuals, a prevalence of moderate and severe dementia of 5.3% was found. When including information on respondents by proxy and institutionalized individuals, the prevalence rate increased to 6.3 and 10.5%, respectively. It will be argued that covering the whole population in question and ensuring high response rates are central issues to minimize selection bias.

Aged↗