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Biomedical subjects

K Schmidt

Publications and source records attributed to K Schmidt.

At least 343 records · Page 19Linked to original sources
PubMed1992

Bromocriptine treatment over 12 years in acromegaly: effect on growth hormone and prolactin secretion.

It is not known whether bromocriptine treatment in acromegaly can be implemented for a life-long period. To elucidate this problem, the secretory GH and PRL states of 12 patients with acromegaly were determined, before bromocriptine treatment, under therapy (15.0 +/- 6.8 mg/day for 12 +/- 3 years; mean +/- SD) and during two-weeks long drug withdrawal after long-term treatment, respectively. Before therapy, all patients showed a non-sufficient GH suppression after oral glucose load (greater than 2 micrograms/l), whereas under dopaminergic treatment the post-glucose GH levels of three patients fell below 2 micrograms/l; normal IGF-I concentrations were found in five patients. However, under bromocriptine, only two patients showed GH suppressions below 2 micrograms/l following glucose, accompanied with normal IGF-I levels. During bromocriptine withdrawal, GH secretion at 60 min in the oral glucose tolerance test increased significantly (17.0 +/- 15.5 vs 5.7 +/- 5.2 micrograms/l; p less than 0.01); the mean IGF-I level rose from 2.1 +/- 0.8 to 4.9 +/- 2.2 kU/l (p less than 0.01). IGF-I was normal during bromocriptine cessation in only one patient; none of the 12 patients showed a GH suppression below 2 micrograms/l after oral glucose load. Under dopaminergic treatment hyperprolactinemia could not be detected. In conclusion, bromocriptine led to a stable suppression of both GH hypersecretion and--if present--concomitantly elevated PRL levels. Severe side effects or a further tumor growth could not be observed. Thus, the data of the longest follow-up investigation that has so far been published indicate that effective life-long bromocriptine therapy seems to be possible in selected patients with acromegaly.

Acromegaly↗
PubMed1992

Large glomerular size in Pima Indians: lack of change with diabetic nephropathy.

The mean glomerular volume, glomerular fraction of cortical volume, and percentage of obsolescent glomeruli were calculated in kidney specimens from autopsies on 34 Pima Indians, of whom 15 had non-insulin dependent diabetes mellitus and kidney disease of diabetes mellitus. These values were compared with those of black, white, and non-Pima native American individuals without diabetes mellitus. Glomerular volume in the Pima Indians was similar in the diabetic and nondiabetic subjects and significantly greater than in the white subjects. Black and non-Pima native American individuals had glomerular volumes intermediate between white individuals and Pima Indians. The mean glomerular volume was not affected by the number of obsolescent glomeruli in diabetic Pima Indians. The glomerular volume fraction was greater in the Pimas than in the other groups. These data showed that glomerular volume in the Pima Indians was significantly greater than that in white subjects. There was no difference between diabetic and nondiabetics Pimas, and glomerular size was not correlated with the presence or degree of glomerulosclerosis in this population.

Adolescent↗
PubMed1992

Sequential concentration of chloroquine in human hair correlates with ingested dose and duration of therapy.

Human scalp hair was analyzed for chloroquine using gas-chromatography. In 5 patients it was demonstrated that the amount of uptake of chloroquine into the hair varied proportionally with the dosage (from 500 mg/week to 10 g single dose) and with the time of administration. The chloroquine concentrations ranged from 8 to 1100 micrograms/g hair. Chloroquine could be determined quantitatively after a single toxic dosage used in a suicidal attempt and also after low therapeutic doses. The sequential examination of the hair shaft allows an assessment of the chloroquine amount taken over time, the individual dosage, the initiation and termination of therapy. As hairs can be collected easily, they are a unique specimen for investigation, and it is suggested that they can virtually be used as a "tachogram" of chloroquine drug-therapy or intoxication.

Adult↗
PubMed1992

[Roentgen findings in T-drainage--results of 311 patients].

Postoperative T Tube cholangiographies of 311 patients from 1980 to February 1992 were evaluated by studying the patient histories and x-ray examinations. Most frequent questions concerned residual stones and papillary occlusion. Most frequent pathological findings were dilatation of the choledochus and of the bile ducts, residual stones and paravasations. Fistulas, abscesses and signs of cholangitis rarely occurred. Dilatation of the choledochus alone did not lead to further treatment. Papillary occlusion was treated by leaving the T drain in situ, patients with occlusion and residual stones were treated by papillotomy, litholysis or lithotripsy. Only 5 patients with necrotizing pancreatitis and abscess had to be reoperated. T tube cholangiography, which at the beginning of the study was a routine postoperative control with minor complications, will surely be applied less frequently in the future due to advances in endoscopy.

Aged↗
PubMed1992

[Prospective study of the cardiovascular risk of patients with sudden deafness].

In this prospective case control study 135 patients with sudden hearing loss were compared with regard to their cardiovascular risk with 135 otologically healthy patients and 111 patients with coronary heart disease. The groups were matched according to age, sex and date of onset of disease. The risk factors investigated were: serum cholesterol, low-density lipoproteins, high-density lipoproteins, triglycerides, blood pressure, body weight, diabetes mellitus, positive family history of coronary heart disease and smoking habits. There was no significant difference between the patients with sudden hearing loss and otologically healthy patients. However, the difference between these two groups of patients and the patients with coronary heart disease was very pronounced. The groups of patients with a low frequency, high frequency or pantonal hearing loss did not differ with respect to the distribution of coronary risk factors. Furthermore, no statistical correlation was found between the degree of recovery of hearing function after sudden hearing loss and coronary risk factors.

Coronary Artery Bypass↗
PubMed1992

HIV infection among intravenous drug users in Copenhagen.

From October 1985 until the end of December 1986, 439 intravenous drug users (IVDU) presented themselves at the outpatient venereal disease clinic of Copenhagen for an HIV-test. HIV-antibodies were found in 53 out of 272 men (19.5%) and in 25 of 167 women (15.0%), giving an overall prevalence of 17.8%. Risk factors for HIV were the length of drug abuse (p less than 0.05) and having injected drugs within the last six months before testing (p less than 0.005). HIV-antibodies were found in 18 of 90 women (20%) and in three of 20 men (15%), who had a history of a past or ongoing life as a prostitute. The IVDU in this study have been chosen as a cohort and recalled for an ongoing follow-up study focusing on drug and sexual behaviour in relation to the initial HIV-test result.

Acquired Immunodeficiency Syndrome↗
PubMed1991

[Somatomedin C level and stimulation of growth hormone and adrenal cortex function by administration of releasing hormones and physical exertion in patients with obesity].

In a clinical study on potential determinants underlying the impairment of growth hormone stimulation in obese human subjects, we examined in 20 otherwise healthy adult obese subjects (14 females, six males, age 18 to 40 years, body mass index greater than 29 kg/m2) the responses of growth hormone (hGH), adrenocorticotropic hormone (ACTH) and cortisol to releasing hormone stimulation (growth hormone-releasing hormone and corticotropin-releasing hormone) and the responses of hGH, ACTH, cortisol and free fatty acids (FFA) to physical exercise. Subjects with somatomedin-C levels less than or equal to 0.7 U/ml (group 1) were more obese than subjects with somatomedin-C levels greater than 0.7 U/ml (group 2) (p less than 0.01). In group 1, hGH increased by 4.3 +/- 1.2 ng/ml in response to releasing hormone administration and by 0.9 +/- 0.3 ng/ml in response to physical exercise (normal responses, increase by greater than 7 ng/ml), in group 2, hGH increased by 6.7 +/- 1.4, and 2.4 +/- 0.8 ng/ml, respectively (p less than 0.05 vs. group 1). Moreover, FFA stimulation by physical exercise was blunted in group 1 (p less than 0.05 vs. group 2). In contrast, ACTH stimulation was found increased in group 1 in comparison to group 2, particularly in response to physical exercise (p less than 0.01), and resulted in enhanced cortisol stimulation (p less than 0.05). Thus, impaired hGH stimulation in obese human subjects is not explained by an altered relationship between hGH and somatomedin-C levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Gallstone dissolution with methyl tert-butyl ether in 120 patients--efficacy and safety.

Of 612 patients with cholesterol gallbladder stones, 120 were eligible for percutaneous transhepatic litholysis with methyl tert-butyl ether (MTBE). Puncture of the gallbladder was successful in 117/120 (97.5%). In 113/117 (96.6%) the stones dissolved. With solitary stones, treatment lasted for an average of 4 hr, with multiple stones 10 hr. Mean hospitalization was 3.6 days. In 3/117 (2.6%) patients a bile leakage developed; 33% reported mild complaints. After the end of treatment 34% had some residue in the gallbladder; two of these patients developed recurrent stones. MTBE is exhaled, is distributed in fatty tissue, and is excreted renally together with its metabolite tert-butanol. Methanol was found only in traces. Gallbladder histology of six patients showed chronic cholecystitis. Since these findings were independent of treatment time and the interval between treatment end and operation, they are most consistent with stone-related changes rather than caused by MTBE.

Adult↗
PubMed1991

Modifications of health behaviour in response to air pollution notifications in Copenhagen.

Ambient air quality is a major issue today in large cities all over the world. On the theoretical background of the health belief model and the health locus of control model, we studied the knowledge and beliefs about air pollution and the modifications of health behaviour brought about by information to the public about projected levels of air pollution, with special emphasis on reduction of outdoor activity and avoidance of car driving. Data were collected with a questionnaire among a sample of residents in the Copenhagen area. The respondents were almost universally knowledgeable about the prime emission source and concerned about the possible health effects of the air pollution in the area. Avoidance of outdoor activity was associated with personal experiences of symptoms ascribed to the air pollution, employment status, and with female sex, but not with knowledge or beliefs about the degree or health implications of the air pollution. The willingness to avoid car driving was positively associated with the belief that one can oneself influence one's health and with female sex. Lung diseased respondents were generally more prone to protect themselves than the healthy, both by avoiding outdoor activity and by being less willing to avoid car driving. The present study was conducted in an only moderately polluted city, and it is not clear whether the findings and conclusions can be generalized to more polluted cities. The study partly supported the underlying theories of the determinants of health behaviour, but also indicated a need for a broader theoretical framework, incorporating aspects of the respondents' life situation and personal experience which would be relevant to the specific type of health behaviour under study.

Adult↗
PubMed1991

Oxidized low-density lipoprotein antagonizes the activation of purified soluble guanylate cyclase by endothelium-derived relaxing factor but does not interfere with its biosynthesis.

Oxidized low-density lipoprotein (LDLox) is a molecule with strong atherogenic properties. In a concentration dependent fashion, LDLox antagonized the activation of purified soluble guanylate cyclase by endothelium-derived relaxing factor (EDRF), which was produced in vitro by incubation of a partially purified EDRF-forming enzyme in the presence of L-arginine, Ca2+ and NADPH. The inhibitory effect of LDLox was potentiated by preincubation of the soluble guanylate cyclase with LDLox, but not when the EDRF-forming enzyme was pretreated with LDLox. As LDLox did not diminish the calmodulin-dependent conversion of L-arginine into L-citrulline by the EDRF-forming enzyme it would appear that EDRF-biosynthesis was not affected by LDLox. It is suggested that the impaired relaxant response of atherosclerotic blood vessels to endothelium-dependent vasodilators was not due to a reduced formation of EDRF but due to a diminished responsiveness of soluble guanylate cyclase.

Animals↗
PubMed1991

Model of kinetic behavior of deoxyglucose in heterogeneous tissues in brain: a reinterpretation of the significance of parameters fitted to homogeneous tissue models.

Effects of tissue heterogeneity on regional CMRglc (rCMRglc) calculated by use of the deoxyglucose (DG) method at 45 min following the pulse of DG were evaluated in simulation studies. A theoretical model was developed to describe the kinetics of DG uptake and metabolism in heterogeneous brain tissues. Rate constants were fitted to simulation data for mixed tissue and rCMRglc computed on the basis of this tissue heterogeneity model. The results were compared with those obtained by use of the original model of the DG method for homogeneous tissue, both without (3K model) and with (4K model) a term to describe an apparent loss of deoxyglucose-6-phosphate (DG-6-P). As a direct consequence of tissue heterogeneity, the effective rate constant for phosphorylation of DG, k3*, declined with time. To compensate for the time-changing k3*, estimates of the dephosphorylation rate constant, k4*, were artifactually high when the 4K model was used, even though no dephosphorylation of DG-6-P actually occurred. The present study demonstrates that the finding of a significant k4*, at least within 45 min following a pulse of DG, may not represent dephosphorylation at all, but rather the consequence of measuring radioactivity in a heterogeneous tissue and applying a model designed for a homogeneous tissue. Furthermore, the high estimates of k4* resulted in significant overestimation of rCMRglc. When rCMRglc was computed with the conventional single-scan or autoradiographic method at 45 min after a pulse of DG, the 3K and tissue heterogeneity models yielded values that were within 5% of the true weighted average value for the heterogeneous tissue as a whole. We conclude that the effects of tissue heterogeneity alone can give the appearance of product loss, even when none occurs, and that the use of the 4K model with the assumption of product loss in the 45-min experimental period recommended for the DG method may lead to overestimation of the rates of glucose utilization.

Brain↗
PubMed1991

Antioxidant vitamins and beta-carotene: effects on immunocompetence.

Adequacy or deficiency in the micronutrient status of an individual deeply affects its immunocompetence. Among the different micronutrients, antioxidative vitamins and beta-carotene are particularly effective in modulating immune functions and host defense against microorganisms or other invasive processes. This involves antigen-specific humoral or cell-mediated reactions of the immune system as well as nonspecific inflammatory processes. Owing to the interactions between micronutrient status and immunocompetence, the assessment of the micronutrient status of an individual can help to predict the risk of specific diseases associated with a deficient or suppressed immunocompetence, eg, infection or cancer. By the appropriate intervention it should be possible to modify this risk as has been shown in a number of carefully controlled studies. Assessment of the immunocompetence of an individual by measuring a limited number of key parameters of the immune system can help in the very early detection of specific micronutrient deficiencies.

Antibody Formation↗