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Biomedical subjects

I Cohen

Publications and source records attributed to I Cohen.

At least 307 records · Page 17Linked to original sources
PubMed1986

Inhibition of platelet factor XIIIa-catalyzed reactions by calmodulin.

Calmodulin was found to exhibit an inhibitory effect on platelet factor XIIIa-catalyzed incorporation of pseudodonor amines into dimethylcasein, platelet actin and myosin. The inhibitory action of calmodulin on the calcium-dependent enzyme reactions was analogous to the effects of EGTA and parvalbumin on these reactions. The extent of inhibition of factor XIIIa activity was a function of calmodulin concentration when factor XIII and Ca2+ concentrations were held constant. These results indicate that calmodulin inhibits platelet factor XIIIa-catalyzed reactions by sequestering calcium.

Actins↗
PubMed1986

Gaucher disease: assessment with MR imaging.

The skeletal system, spleen, and liver of five patients with proved Gaucher disease were studied with magnetic resonance (MR) imaging. Homogeneous, low intensity signals resulting from relaxation times different than normal (longer T1 and shorter T2 values) were found in the marrow of long bones, vertebrae, and hips in all patients. In three patients, normal signals were noted in the patella, epiphysis of the knee, and capital femoral epiphysis. In two patients with acute bone pain in the tibial region, a higher signal was received from the tibial marrow. This signal was related to increased accumulation of fluid following an avascular episode. Soft tissues in the same area were also involved. Liver and spleen enlargement was readily visible, especially on coronal images. T1 values of spleen were significantly shorter than normal. MR imaging provides an excellent assessment of the extent of involvement of the liver, spleen, and bone marrow in Gaucher disease.

Adolescent↗
PubMed1986

Nuclear magnetic resonance proton imaging of bone pathology.

Thirty-two patients with diversified pathology were examined with a supraconductive NMR imager using spin echo with different TR and TE to obtain T1 and T2 weighted images. They included 20 tumors (12 primary, eight metastasis), six osteomyelitis, three fractures, two osteonecrosis, and one diffuse metabolic (Gaucher) disease. In all cases except for the stress fractures, the bone pathology was clearly visualized in spite of the normal lack of signal from the compact cortical bone. Nuclear magnetic resonance (NMR) imaging proved to be at least as sensitive as radionuclide scintigraphy but much more accurate than all other imaging procedures including computed tomography (CT) and angiography to assess the extension of the lesions, especially in tumors extended to soft tissue. This is due both to easy acquisition of sagittal and coronal sections and to different patterns of pathologic modifications of T1 and T2 which are beginning to be defined. It is hoped that more experience in clinical use of these patterns will help to discriminate between tumor extension and soft-tissue edema. We conclude that while radionuclide scintigraphy will probably remain the most sensitive and easy to perform screening test for bone pathology, NMR imaging, among noninvasive diagnostic procedures, appears to be at least as specific as CT. In addition, where the extension of the lesions is concerned, NMR imaging is much more informative than CT. In pathology of the spine, the easy visualization of the spinal cord should decrease the need for myelography.

Adolescent↗
PubMed1986

Immunogenetics of juvenile chronic arthritis in Israel.

Typing for HLA-A,B,C and DR antigens was performed in 61 Israeli patients with juvenile chronic arthritis (JCA) and in 120 unrelated controls. No significant associations were apparent in the overall patient group. DR5 was significantly increased in the non-Ashkenazi patients with pauciarticular onset of disease. The only three DRw8 positive patients in the study had pauciarticular onset. DR5 and DRw8 were found in 9 of 10 patients with age of onset less than 3 years. Increased frequencies of Bw50 and Cw6 were observed in patients with systemic onset. Typing for properdin factor (Bf) and glyoxylase (GLO) was carried out in 45 and 50 of the patients, respectively. No associations with alleles of the complement Bf system or the HLA linked GLO system were evident. The confirmation in the ethnically distinct Israeli population of the previously described association of DR5 with pauciarticular JCA suggests that this gene may be closely related to the disease susceptibility gene.

Adolescent↗
PubMed1986

Perinatal factors influencing outcome of very-low-birth weight infants.

Of 106 liveborn infants weighing 751 to 1,500 g born to 97 mothers, 97 (91.5%) were transferred to the Neonatal Intensive Care Unit for premature infants at the Beilinson Medical Center, Petah Tikva. Treatment with tocolytic agents (ritodrine) and corticosteroids (betamethasone) was introduced when indicated but no preventive antibiotics were used during the antenatal period. All infants received immediate care by a neonatologist and 77 infants (72.6%) survived. Although the cesarean section deliveries increased during the survey from 21.7% during the first period to 43.3% during the second, there was no statistically significant difference in the survival rate. Thus it seems that there is no advantage in performing cesarean sections for very-low-birth weight infants in either vertex or breech presentations.

Critical Care↗
PubMed1985

Localizing the site of generation of uni-quantal endplate potentials using two intracellular microelectrodes.

By recording with a microelectrode at either end of the endplate, the site of generation of uni-quantal endplate potentials (EPP) can be estimated. One method assumes that the logarithm of the amplitude of the signal declines linearly with distance along the cable [4, 8]. The uncertainties in this method are discussed. We show that even on a muscle cable the logarithm of the time integral of the EPP declines linearly with distance, falling to 1/e at a distance equal to the length constant, lambda. We conclude that the integral approach provides a theoretically sound method for localizing the sites of uniquantal EPP generation with two microelectrodes.

Animals↗
PubMed1985

The effect of water intake on body temperature during rugby matches.

The effect of drinking up to 1 litre of fluid on water deficit, sweat loss and rectal temperature was determined during three separate rugby matches played in thermoneutral environments. Each player was allotted a litre of fluid and encouraged to drink 500 ml before the start of the game and a further 500 ml at half-time. The players were weighed and rectal temperatures determined before and after the matches. Rectal temperatures were markedly elevated after all three matches and reached levels which may have been high enough to have impaired performance towards the end of the game. The volume of fluid ingested by the players had no influence on final rectal temperatures. The majority of the players had sweat rate/rectal temperature relationships similar to those of heat-acclimatized subjects. It is concluded that, in a thermoneutral environment, the ingestion of volumes of fluid up to 1 litre has no significant beneficial effect on thermoregulation during rugby games, and that the role of the clothing worn may have a greater influence on thermoregulation than was hitherto envisaged.

Adult↗
PubMed1985

In vitro studies of a new synthetic thrombin inhibitor.

(2R, 4R)4-methyl-1-[N alpha-(3-methyl-1,2,3,4-tetrahydro-8-quinoline- sulfonyl)-L-arginyl]-2-piperidine carboxylic acid monohydrate (MCI-9038) was found to be a potent synthetic inhibitor of thrombin. In concentrations as low as 1 microM, the thrombin time, prothrombin time, and partial thromboplastin time were more than doubled. The venom (Bothrops atrox) time was similarly prolonged. The drug also inhibited the thrombin-induced activation of factors VIII and XIII. While MCI-9038 in concentrations of 10(-4) M had no effect on platelet aggregation induced by collagen, ADP, epinephrine, and arachidonate, nanomolar concentrations inhibited thrombin-induced platelet aggregation and the release of platelet ADP. The drug also significantly inhibited the adhesion of thrombin-treated platelets to cultured bovine aortic endothelial cells. We conclude that MCI-9038 is an extremely potent inhibitor of the effects of thrombin on platelets and clotting factors.

Arginine↗