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Biomedical subjects

J Menczel

Publications and source records attributed to J Menczel.

At least 37 records · Page 2Linked to original sources
PubMed1986

Influence of aluminum on mineralization during matrix-induced bone development.

A model of de novo mineralization employing matrix-induced endochondral bone formation in rats was used to study the short-term effects of aluminum on the deposition of calcium and phosphate in vivo. In experiments where systemic aluminum concentrations were elevated, the cellular processes associated with bone development appeared to be normal, if somewhat delayed, however precipitation of the mineral phase was prevented. This suggests a primary direct physical chemical effect of aluminum in vivo on calcification, as suggested by in vitro studies which demonstrate that aluminum is a potent inhibitor of calcium phosphate precipitation. Aluminum salts implanted locally with the matrix appeared to be toxic to the cellular processes leading to chondrogenesis and osteogenesis.

Alkaline Phosphatase↗
PubMed1986

The inhibitory guanine nucleotide regulatory protein modulates agonist-stimulated cAMP production in rat osteosarcoma cells.

We identified the subunits of the stimulatory and inhibitory guanine nucleotide binding proteins (Gs and Gi, respectively) associated with adenylate cyclase in rat osteosarcoma (ROS) cells. Pertussis toxin catalyzed ADP-ribosylation of Gi alpha in ROS cells increased agonist (PTH and isoproterenol)-stimulated, but not basal, cAMP production. The effect of pertussis toxin was dose and time dependent, and slowly reversible (T 1/2 approximately 30 h) during continued culture without toxin. Pertussis toxin treatment of ROS cell lines (17/2.8 and 24/l) with markedly different agonist responsiveness increased agonist-stimulated cAMP production in proportion to the response without toxin treatment. Pertussis toxin treatment further increased cAMP response to PTH in dexamethasone treated cells. We conclude that ROS cells contain functional Gi which modulates agonist-stimulated cAMP formation. Alterations in ROS cAMP responsiveness caused by steroids, and the reduced responsiveness of the 24/1 cell line, however, are unlikely to be due to changes in Gi.

Adenylate Cyclase Toxin↗
PubMed1986

Preventing osteoporosis: current practices and problems.

A lateral x-ray of the thoracic and lumbar spine should be part of the routine examination of any woman aged 40 or older. Similarly, an anteroposterior x-ray of the hand as a first assessment may suggest a need for further investigation for osteoporosis. Estrogen treatment reduces the incidence of vertebral compression and has proven protective against central as well as peripheral bone loss. However, rapid bone loss after termination of estrogen therapy implies that the protective effect may last no longer than 2 to 3 years.

Adult↗
PubMed1985

Hypoglycemia-induced hemolysis in glucose-6-phosphate dehydrogenase deficiency.

We present a young man with Mediterranean type glucose-6-phosphate dehydrogenase (G6PD) deficiency and insulin-dependent diabetes mellitus whose brittle course was characterized by recurrent bouts of hypoglycemia and diabetic ketoacidosis (DKA). While neither of the episodes of DKA was complicated by hemolysis, hemolytic anemia consistently followed the recurrent attacks of hypoglycemia. Stringent control of the patient's blood glucose levels in the upper limit and slightly above the normal range successfully prevented recurrence of hypoglycemia and recrudescence of hemolytic anemia. Hypoglycemia is proposed as capable of inducing hemolysis in G6PD deficiency.

Adult↗
PubMed1985

The effect of age on beta-adrenergic function in man: a review.

The structure and function of the beta-adrenergic adenylate cyclase complex in the elderly is reviewed. The function of the beta-adrenergic receptor in man is modulated by levels of circulating catecholamines, noncatecholamine hormones, drugs, disease, and age. Although a number of clinical observations demonstrate an age-related decrease in catecholamine responsiveness, the molecular basis of this phenomenon is unknown. Simple reduction in beta-receptor number does not appear to explain age-associated loss of catecholamine responsiveness. Recent investigations from our laboratory employed salbutamol-induced rise in plasma cyclic AMP (cAMP) levels to study the molecular basis for this phenomenon. In young individuals there was a threefold increase in plasma cAMP levels after salbutamol infusion. In older subjects only a 50% rise in plasma cAMP levels was observed. These results suggest that the basis for reduced catecholamine responsiveness in the elderly is due to a defect in the peripheral beta-receptor-linked adenylate cyclase complex. The finding of reduced beta-adrenergic-stimulated adenylate cyclase activity in the aged prompted us to determine the specificity of this decline by measuring the activity in older and younger individuals of another hormone-sensitive adenylate cyclase. However, no effect of subject age was observed on glucagon-sensitive adenylate cyclase activity, suggesting that the blunted response of the beta-receptor adenylate cyclase complex in the elderly represents a specific loss of function and is not due to a general age-associated decline in hormone-stimulated cyclase function. Specific molecular defects which could account for decline in beta-adrenergic responsiveness in the elderly are discussed.

Adenylyl Cyclases↗
PubMed1985

Comparison of verbal and nonverbal memory in elderly normal subjects and dementia patients.

A multimodal memory test was devised to investigate the differences between verbal and nonverbal memory in demented and normal older people (65 to 98 years of age). Recognition memory for faces, geometric designs, tactual fabrics, words, and sentences significantly differentiated between the two groups. Verbal memory was better than nonverbal memory in both groups. No differences in subtest profiles were found between groups. Findings suggest that the verbal-nonverbal dimension is of importance to rehabilitation programs. The relatively slow deterioration of verbal memory with age leads to the suggestion that verbal memory might be capitalized on for the creation of compensatory mechanisms. The similarity in subtest profiles is in agreement with the accelerated aging hypothesis of dementia.

Adult↗
PubMed1984

Diabetic ketoacidosis does not precipitate haemolysis in patients with the Mediterranean variant of glucose-6-phosphate dehydrogenase deficiency.

Diabetic ketoacidosis is traditionally stated as being capable of precipitating haemolysis in patients deficient in glucose-6-phosphate dehydrogenase (G6PD). This, however, is based on only a few case reports with inadequate documentation. A study was therefore conducted to review the subject in people with the Mediterranean variant of G6PD deficiency. Perusal of the medical records for the years 1970-82 yielded 15 patients with G6PD deficiency who had been admitted to hospital for a total of 36 episodes of diabetic ketoacidosis. Ten of these episodes had been complicated by haemolytic anaemia, but in every one there was unequivocal evidence of either concurrent bacterial infection or inadvertent ingestion of drugs, either of which might induce haemolysis in G6PD deficient patients. In the remaining 26 episodes there was no evidence of developing or established haemolytic anaemia. From these findings diabetic ketoacidosis should not be regarded as a risk factor for haemolysis in the Mediterranean variant of G6PD deficiency.

Adult↗
PubMed1984

Low serum 24,25 dihydroxyvitamin D in Duchenne muscular dystrophy.

Levels of serum 24,25(OH)2D3 (0.69 +/- 0.17 ng/ml) were lower in DMD patients than in age-matched controls (2.13 +/- 0.15 ng/ml). Circulating levels of 1,25(OH)2D3 and 25(OH)D3 were within the accepted normal range. Bearing in mind the proposed pathophysiologic role of calcium in DMD and the influence of vitamin D metabolites on muscle ATP and protein synthesis, as well as on sarcoplasmic reticulum calcium transport and muscle mitochondrial calcium content, the above findings of low or deficient 24,25(OH)2D3 levels in DMD could be meaningful from the etiologic and therapeutic points of view.

24,25-Dihydroxyvitamin D 3↗
PubMed1984

Maternal-fetal transfer of aminophylline.

Ten women with normal pregnancies who underwent an elective cesarean section received orally 200 mg of aminophylline every 6 hours for 24 - 36 hours prior to surgery. The levels of aminophylline and caffeine were measured in maternal and cord sera and in amniotic fluids. The mean level of aminophylline (+/- SD) in maternal serum was 10.4 +/- 1.74 micrograms/ml, and in cord serum 11.2 +/- 1.25 micrograms/ml. The mean aminophylline level in amniotic fluids was 8.2 +/- 1.42 micrograms/ml. The serum aminophylline levels were within the therapeutic level range. Caffeine levels in those specimens ranged between traces to 6 micrograms/ml which correspond to the normal dietary range.

Aminophylline↗
PubMed1984

Increased placental concentrations of 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 in pregnant rats treated with human chorionic gonadotropin.

Pregnant rats were injected intrajugularly with 2500 i.u. human chorionic gonadotropin (HCG) toward the end of gestation (days 18-19) and 7.0 pmoles of tritiated 25-hydroxyvitamin D3 [( 3H]25(OH)D3) the following day. They were sacrificed ten to 24 hours later. [3H]25(OH)D3 and the in vivo produced [3H]24,25-dihydroxyvitamin D3 [( 3H]24,25(OH)2D3) in lipid extracts from maternal serum, kidneys, placenta and fetal tissues were separated by Sephadex LH-20 chromatography, and high performance liquid chromatography (HPLC). HCG treatment of pregnant rats increased significantly 25(OH)D3 levels in the placenta and kidneys and 24,25(OH)2D3 level in the placenta. Fetal metabolites levels were unaffected by HCG treatment. Serum and kidney levels of 25(OH)D3 and 24,25(OH)2D3 in pregnant rats were significantly lower than in non-pregnant rats. Serum and kidney levels of both metabolites in non-pregnant female rats treated with HCG did not differ from the untreated controls. HCG may, therefore, be involved in regulation of fetoplacental vitamin D metabolism.

Animals↗
PubMed1984

A predictor index for hospitalization for patients with acute asthmatic attack.

Thirty-nine patients, aged 14 to 50 years (mean 33), were treated for an acute asthmatic attack in the hospital emergency room. A scored index was estimated on admission for each patient, based on pulse, respiratory and peak expiratory flow rates (PEFR), amplitude of paradoxical pulse and degree of dyspnea, wheezing and accessory muscle use. All patients were treated according to a standard protocol including oxygen, fluids, salbutamol inhalations and aminophylline infusions, with hydrocortisone infusion in selected patients. The decision to hospitalize of discharge was based on clinical grounds and was taken after 4 to 8 h of treatment without prior knowledge of the patient's index. The mean index of 13 hospitalized patients (Group 1) was 4.5 +/- 1.7 (mean +/- 2 SD), compared with 4.3 +/- 1.3 of 7 patients who were discharged but returned for additional treatment within 10 days (Group 2). Both indices were significantly higher than that of 19 patients who were discharged and remained well (2.5 +/- 1.5) (Group 3). The most important differentiating parameters were the degree of dyspnea, wheezing and PEFR. We conclude that patients with scored indices of greater than 4 should be hospitalized immediately, those with indices less than 4 could probably be discharged with relative safety, and patients with an index of 4 should be considered individually, with dyspnea, wheezing and PEFR being the major criteria for the decision.

Acute Disease↗
PubMed1983

Screening for cognitive deficits in a sample of hospitalized geriatric patients: a re-evaluation of a brief mental status questionnaire.

A 30-item screening examination for cognitive deficits was administered to 65 hospitalized elderly patients and to 60 elderly controls. A high proportion (73 per cent) of the hospitalized patients were found to have low cognitive scores indicative of probable organic mental syndrome (OMS). Especially high deficits were found among the patients with orthopedic and cerebrovascular conditions. The test correctly identified the 15 cases of established OMS. The percentage of false positive results in the normal controls was reasonably low. The importance of routine cognitive measurements in medical wards is stressed.

Aged↗