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Biomedical subjects

L Stern

Publications and source records attributed to L Stern.

At least 55 records · Page 3Linked to original sources
PubMed1988

New techniques in diagnosis, assessment of progression and research in muscular dystrophy.

A number of imaging techniques has been used in Duchenne muscular dystrophy and other neuromuscular conditions. Ultrasound reflects the changes occurring in muscle and allows differentiation between myopathies and neuropathies. It may also be of help in deciding where to take a needle biopsy. Computerized tomography (CT) has been used to assess progression over a 6 month period in Duchenne dystrophy. The density changes observed on CT scans give an accurate indication of progression and will be a useful tool in clinical trials. CT scans of obligate carriers of Duchenne dystrophy showed lower muscle densities than male controls. Magnetic resonance imaging also accurately reflects pathological changes in muscle. A pilot project to improve respiratory muscle strength and endurance showed that it was possible to improve endurance. A longer term project is currently being carried out to improve respiratory muscle endurance by the use of computer games connected to a thermistor. A certain inspiratory effort is required to continue the games, which provide the motivating factor.

Adolescent↗
PubMed1987

[Determination of central hemodynamics in dynamic stress using impedance cardiography in comparison to radiocardiography].

77 unselected patients were examined synchronously by impedance and radiocardiography in recumbent position during dynamic exercise. In all cases the load of evaluable impedance curves was possible till 100 watts. Stroke volume, estimated by impedance cardiography, is lower about 30% at rest and during exercise compared to its estimation by radiocardiography. But the percentual increase during exercise is not significantly different between the methods. The stroke volumes, estimated by both methods, correlate significantly at rest and during exercise. This fact shows the usefulness of impedance cardiography for estimating central haemodynamics during dynamic exercise.

Cardiography, Impedance↗
PubMed1987

Aggregation of bilirubin in injectates and incubation media: its significance in experimental studies of CNS toxicity.

In experimental work with bilirubin toxicity, incubates or injectates are prepared without added albumin, or with a molar excess of bilirubin over albumin. Bilirubin is liable to aggregation as free bilirubin acid under these circumstances, giving rise to variable toxicity. Stable solutions are obtained with a molar excess of albumin over bilirubin; such solutions show no toxicity, however. It is suggested that this difficulty may be circumvented by using an excess of albumin, adding a sulfonamide as a bilirubin displacer, to provoke toxicity.

Animals↗
PubMed1986

[Relation of the impedance cardiogram to the course of myocardial contraction].

53 patients with coronary heart disease were investigated synchronously by means of impedance and angiocardiography combined with the measurement of the pressure in the aorta and the left ventricle. In these cases relatively close correlations were found between the stroke volumes and systolic time intervals, determined by the two methods, as well as between the ejection fraction on the one hand and the parameter dz/dt max on the other. The pressures, measured invasively, do not correlate significantly with the impedance cardiography parameters. With help of the relations found it is possible to coordinate the changes of the thoracic impedance curve depending on the heart action with the various phases of the left-ventricular volume change.

Cardiography, Impedance↗
PubMed1986

Respiratory muscle training in Duchenne muscular dystrophy.

Eighteen boys with Duchenne muscular dystrophy were entered into trials to assess the effects of specific ventilatory strength and endurance training programmes. The findings showed an improvement in ventilatory muscle endurance but not in strength as a result of specific respiratory muscle training. The clinical significance of these findings is uncertain, however, and needs further evaluation.

Adolescent↗
PubMed1986

A comparison of selective media for the isolation of anaerobic bacteria from clinical material.

Clinical specimens submitted for anaerobic culture to a Melbourne teaching hospital microbiology laboratory were plated onto 3 types of selective media, to determine which would allow the optimal recovery of anaerobic organisms. The 3 media employed were kanamycin agar (KA), neomycin agar (NA) and nalidixic acid-Tween 80 agar (NAT). The highest isolation rate was achieved on NAT, 89% of the total of all anaerobes isolated being recovered on this medium. A recovery rate of 69% was achieved using NA, while use of KA allowed the isolation of only 56% of all strains. The major difference between 3 media was in the recovery of anaerobic Gram-positive cocci, which accounted for 40% of the total isolates on NAT, 25% on NA, and only 11% on KA. The NAT was also more successful in the isolation of Fusobacterium and Veillonella species. The NAT medium failed, however, to recover Clostridium spp. that were isolated on both NA and KA. There was no significant difference between the 3 media in regard to the recovery of Bacteroides spp.

Abscess↗
PubMed1986

Dysgonic fermenter-2 septicemia.

A 62 yr-old man with a recent history of dog bite and a past history of splenectomy developed septicemia and signs suggestive of a generalized Schwartzman reaction, including fever, hypotension, symmetrical peripheral gangrene and laboratory evidence of consumptive coagulopathy. The causative organism was a Dysgonic Fermenter-2 (DF-2), a designation given to an unnamed group of Gram-negative rod shaped bacteria. This organism has not previously been reported in Australia. A review of documented cases of serious infection suggests that splenectomy and dog bite are predisposing factors to disease caused by this organism.

Animals↗
PubMed1985

Thrombotic thrombocytopenic purpura syndrome in systemic lupus erythematosus: treatment with plasma infusion.

Two patients with well documented systemic lupus erythematosus developed a syndrome resembling thrombotic thrombocytopenic purpura. Both had severe thrombocytopenia, microangiopathic hemolytic anemia, seizures, and renal dysfunction. Prothrombin time, partial thromboplastin time, thrombin time, and fibrinogen levels were normal; fibrin degradation products were minimally elevated. Histologic evaluation of renal biopsies in both patients confirmed the impression of intravascular thrombosis. Therapy with corticosteroids, other immunosuppressive drugs and splenectomy (in one case) proved unsuccessful. The infusion of fresh frozen plasma, with or without plasmapheresis, reversed the syndrome. This report indicates that patients with systemic lupus may develop a thrombotic thrombocytopenic purpura like syndrome which responds to fresh plasma infusion.

Adrenal Cortex Hormones↗
PubMed1985

Effect of cortical-medullary gradient for ammonia on urinary excretion of ammonia.

Previous studies suggested that a portion of ammonia secreted into the proximal tubule may diffuse directly from Henle's loop into the medullary collecting duct. Since water is absorbed along the course of the descending portion of the loop, it was proposed that the concentration of ammonia increased in loop fluid, and that rapid diffusibility of the free base would facilitate the delivery of ammonia into medullary interstitium where a high level could be maintained by the countercurrent exchange process. In this schema it was proposed that there was an ammonia concentration gradient between medullary structures and cortex, and recovery of ammonia by the medullary collecting duct due to the low pH in tubule fluid at that site. The present study was designed to evaluate this hypothesis by estimating ammonia concentrations in medullary and cortical tissue, and by correlating medullary levels with secretion rate into the inner medullary collecting duct. In control animals the concentration of total ammonia (NH4+ + NH3+) in inner medullary vasa recta was 9.2 +/- 1.5 mumoles/ml, a level 100-fold higher than the cortical level of 0.10 +/- 0.01. During acute acidosis the medullary level rose to 22.5 +/- 2.7 mumoles/ml, but in acute acidosis during mannitol infusion the level fell to 8.0 +/- 1.2. The rate of ammonia secretion into inner medullary collecting duct fluid correlated directly with medullary vasa recta ammonia concentration. These data provide evidence for a steep ammonia concentration gradient between the medulla and cortex, and suggest that the diffusion gradient across collecting duct epithelium governs the rate of the addition of ammonia to collecting duct fluid.

Acidosis↗
PubMed1984

Inhibition of experimentally-induced murine metastases by recombinant alpha interferon: correlation between the modulatory effect of interferon treatment on natural killer cell activity and inhibition of metastases.

The effect of a human recombinant hybrid alpha interferon (referred to as rHuIFN-alphaA/D) on pulmonary metastases induced by intravenous injection of B16 F10 melanoma cells in C57BL/6 mice was examined; rHuIFN-alphaA/D has been previously shown to have anti-viral, anti-proliferative and immunomodulatory activities in murine cells. Pretreatment of mice with 4 daily intraperitoneal injections of rHuIFN-alphaA/D resulted in a marked decrease in the number of pulmonary metastases. This inhibition was dose-dependent but was not seen when mice were similarly treated with rHuIFN-alphaA, a human recombinant alpha interferon subtype which is inactive on murine cells. Treatment of mice with rHuIFN-alphaA/D following B16 F10 injection resulted in no significant inhibition of pulmonary metastases. Mice given a similar treatment regimen of rHuIFN-alphaA/D had elevated natural killer (NK) cell activity as measured by in vitro cytotoxicity against YAC-I or in vivo pulmonary clearance of B16 F10 cells. Pretreatment of mice with 10 daily injections of rHuIFN-alphaA/D resulted in decreased NK activity and less inhibition of metastases. Therefore, in this model system, rHuIFN-alphaA/D inhibits metastases when given in the appropriate treatment schedule. Furthermore, the data are consistent with the hypothesis that rHuIFN-alphaA/D-induced inhibition is a consequence of the immunomodulation of NK cells, which prevent the establishment of pulmonary metastases.

Animals↗
PubMed1984

Decarboxylation of L-dopa and 5-hydroxytryptophan in dispersed rat pancreas acinar cells.

Amino acid decarboxylation activity in dispersed rat pancreas acinar cells and fractions derived by differential centrifugation of homogenate of these cells was studied. The rate of decarboxylation was measured by determining the rate of production of the [3H]-amine from [3H]-amino acid or the rate of production of 14CO2 from the [14C]-carboxy-labelled amino acid. Only the hydroxylated amino acids L-dopa and 5-hydroxytryptophan are decarboxylated by intact dispersed pancreas acinar cells or cell homogenates at all pH values and amino acid concentrations tested. The decarboxylase activity is located exclusively in the cell cytosol. Each substrate competitively inhibits the decarboxylation of the other and the decarboxylation of each is inhibited by NSD-1055. The estimated Km and Vmax are, for L-dopa, 4.8 X 10(-5) M and 2.5 nmol/mg protein/min and for 5-hydroxytryptophan, 2.9 X 10(-5) M and 0.3 nmol/mg protein/min. The pH optimum for 5-hydroxytryptophan decarboxylation is from 7.0-8.5 while that for L-dopa is 7.0. It is concluded that pancreas acinar cells possess a single aromatic amino acid decarboxylase specific for the hydroxylated amino acids L-dopa and 5-hydroxytryptophan, and which is similar in all properties studied to the aromatic amino acid decarboxylase found in several other mammalian tissues.

Animals↗
PubMed1984

The management of hyperbilirubinemia.

When pre-established "safe" limits of serum bilirubin are exceeded, or when hyperbilirubinemia is present in association with other conditions such as prematurity with respiratory distress, asphyxia, or neonatal infections, the need to lessen the risk of bilirubin encephalopathy requires specific and effective interventions to lower the unconjugated or indirect-reacting bilirubin level in infants at risk. To this end the authors examine the criteria for intervention, the means of decreasing serum bilirubin levels, phototherapy, exchange transfusion, and the problem of jaundice in breast-fed infants.

Blood Volume↗