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Biomedical subjects

S Katz

Publications and source records attributed to S Katz.

At least 271 records · Page 15Linked to original sources
PubMed1987

Effects of Ca2+, Mg2+ and calmodulin on the formation and decomposition of the phosphorylated intermediate of the erythrocyte Ca2+-stimulated ATPase.

Formation of the phosphorylated intermediate (ECaP) of the human erythrocyte Ca2+-stimulated ATPase (Ca2+-ATPase) was more rapid and reached steady state sooner at 400 microM-Ca2+ than at 1 microM-Ca2+. Calmodulin increased the apparent rate of ECaP formation at 1 microM-Ca2+, whereas at 400 microM-Ca2+, calmodulin decreased the steady-state level of the ECaP without affecting its apparent rate of formation. Removal of endogenous Mg2+ with trans-1,2-diaminocyclohexane-NNN'N'-tetra-acetic acid, which decreased both the velocity and Ca2+-sensitivity of the Ca2+-ATPase, did not alter the Ca2+-sensitivity or the apparent rate of formation of ECaP. ECaP formation at high Ca2+ concentrations was not affected by Mg2+ concentrations as high as 1 mM, and the ECaP could be dephosphorylated by ADP and ATP along either the forward or reverse pathways. The results suggest that high Ca2+ concentrations inhibit Ca2+-ATPase activity by preventing dephosphorylation of the E2P complex, rather than by inhibition of the transformation from E1CaP ('high-Ca2+-affinity' ECaP) to E2CaP ('lower-energy' ECaP).

Adenosine Diphosphate↗
PubMed1987

Involution of the antimesometrial decidua in the mouse. An ultrastructural study.

Involution of the antimesometrial decidua was analysed by electron microscopy on days 9, 10 and 11 of pregnancy in the mouse. During this period, the width of the antimesometrial decidua decreases considerably. Involution begins in the decidual cells situated closest to the embryo (internal decidua) and proceeds towards the myometrium. The cells of the internal decidua showed signs of deterioration characterized by accumulation of clumps of chromatin in the nuclei and dilation of the perinuclear cisterna and endoplasmic reticulum cisternae. Autophagosomes and heterophagosomes accumulated in the cytoplasm of these cells. Cells particularly strongly affected became spherical and were devoid of their plasma membrane. Some cells near the trophoblast as well as the mature decidual cells situated farther from the embryo showed a normal morphology. The trophoblastic cells established close contact with healthy decidual cells and engulfed fragments of disorganized decidual cells. It is suggested that the death of decidual cells is a type of programmed cell death and that it is not due to a direct lytic action by the trophoblast.

Animals↗
PubMed1987

The hierarchical relationship between activities of daily living and instrumental activities of daily living.

A three-level hierarchical scale including IADL (shopping and transportation) and ADL (bathing, dressing, transferring, and feeding) was tested and validated based on secondary analysis of three studies of elders in the community: a population-based sample, the Cleveland-GAO, and two service-based samples, the Alternative Health Services Project, a study of Medicaid-eligible elders in Georgia, and the Section 222 Homemaker-Day Care study, a sample of Medicare-eligible elders. Scalability analysis included evaluation of Kronbach's alpha, Guttman analysis, and analysis of the pairwise association of individual items using phi/phi max. Validation included discriminant validity and predictive validity. With respect to discriminant validity, the negative association between functional ability (as measured by the scale) and age was observed. With respect to predictive validity, the negative relationship between functional ability (as measured by the scale) and risk of decline to ADL, death, and hospitalization in a year was observed. A six-level scale similar in structure and detail to the Katz Index of ADL was examined with the three studies. This scale can be used to described a broader range of needs of elders in the community and will be particularly useful to health services planners, practitioners, and researchers.

Activities of Daily Living↗
PubMed1987

Intracellular free calcium levels in mononuclear cells of patients with cystic fibrosis and normal controls.

The time course of resting free intracellular calcium concentrations in isolated mononuclear blood cells following a one hour incubation period with the fluorescent dye quin2 was evaluated. Under equal experimental conditions, a slow time-dependent increase of intracellular free calcium in patients with cystic fibrosis and normal healthy controls was noted. Using regression analysis, cystic fibrosis patients were seen to exhibit significantly higher free intracellular calcium concentrations than the controls over the time span covered. At an arbitrarily selected time (60 minutes) the free calcium level was 143.7 +/- 4.3 nM (SEM) in the patients, and 125.5 +/- 2.6 nM in controls. From these data it is concluded that neglecting the time-dependent (Ca2+)i changes following quin2 incubation leads to over- and/or underestimation of the unstimulated resting, basic free calcium levels and prevents the detection of differences between normals and cystic fibrosis patients.

Adolescent↗
PubMed1987

The effect of high-dose phenylephrine versus epinephrine on regional cerebral blood flow during CPR.

Prior studies have not found the alpha agonist phenylephrine, in a dose of 0.1 mg/kg, to be as effective as 0.20 mg/kg of epinephrine in improving regional cerebral blood flow (CBF) during CPR in swine. We undertook this study to assess whether higher doses of phenylephrine might improve regional CBF. Fifteen swine were allocated to receive either epinephrine 0.2 mg/kg, phenylephrine 1.0 mg/kg, or phenylephrine 10 mg/kg. Regional CBF measurements were made during normal sinus rhythm, during CPR, and during CPR following drug administration. Epinephrine 0.2 mg/kg was significantly better in improving regional CBF to the left and right cerebral cortices, cerebellum, midbrain, and cervical cord than was phenylephrine 1.0 mg/kg. There was no significant difference in regional CBF between the animals receiving epinephrine 0.2 mg/kg and phenylephrine 10 mg/kg. The study shows that large doses of epinephrine and phenylephrine may be required during CPR to improve regional cerebral blood flow following a prolonged arrest.

Animals↗
PubMed1987

Non-operative management of traumatized spleen in children: the role of open abdominal tap.

Experience with non-operative management of paediatric splenic trauma in 12 children, and current treatment protocol are presented. Splenic injury was confirmed in all instances by scintiscan. Under close observation no evidence of rebleeding was found. In one patient with persistent fever, peritoneal irritation and leukocytosis open abdominal tap was performed in order to eliminate other intra-abdominal injury and conservative treatment continued. Average stay in hospital was 11 days. Patients recovered fully by six weeks and repeat scintiscan at three months were normal in 9 patients and greatly improved in the other three. Most children sustaining splenic injury may be non-operatively managed. In a special subgroup of moderate bleeders open abdominal tap may increase the safety of this approach and reduce the number of superfluous laparotomies to a minimum.

Adolescent↗
PubMed1987

Intussusception in a premature infant simulating necrotising enterocolitis.

Intussusception in older infants is manifested by bloody stools, colicky abdominal pain and a palpable abdominal mass. In neonates the symptoms are often restricted to vomiting, guaiac positive stools and abdominal distension. These symptoms closely mimic necrotising enterocolitis. Surgical treatment of necrotising enterocolitis should be postponed until perforation of the gastrointestinal tract has occurred, whereas, prompt surgical treatment is recommended for intussusception. We report a case of intussusception that simulated necrotising enterocolitis in a 740 grammes premature infant in the second week of life. The clinical and radiographic features are described and the difficulty in distinction between the two conditions is emphasised. Neonatologists and paediatric surgeons should always include intussusception in the differential diagnosis of abdominal distension and guaiac positive stools in small premature infants.

Diagnosis, Differential↗
PubMed1987

Congenital aneurysms of the deep veins of the lower extremities.

This is a report of our experience with seven children with congenital aneurysms of the deep veins of the lower extremities. All the patients had various clinical features of angiodysplasia. With the use of ascending functional phlebography the patients were divided into two groups: four patients with fusiform aneurysms and three patients with saccular aneurysms. Patients in group 1 had venous reflux and a mild degree of venous insufficiency, which were surgically treated. Three patients with saccular aneurysms (group 2) showed no signs of venous insufficiency and are still being carefully followed. Anatomic and functional assessment of the deep venous system by ascending functional phlebography is essential for planning an appropriate treatment for this rare clinical entity.

Aneurysm↗
PubMed1987

Why there is no error in the direct theory of perception.

According to Gibson's direct theory, perception is an achievement, not a process. Perceptual error, therefore, is the failure to perceive. Taken in isolation, this assertion leads to implausible consequences, but taken together with other assertions of Gibson, it may be understood, without contradiction, to mean that there is no absolute error in perception. Whether perception is successful or not is determined by the context in which the perceptual act occurs.

Achievement↗
PubMed1987

Intracellular calcium and sodium in hypertensive patients.

Untreated subjects with mild to moderate hypertension were compared with normotensive controls recruited from the same ambulatory screening clinic. All subjects were black. Resting levels of cytosolic free calcium were estimated in washed platelets with the fluorescent intracellular probe fura 2, and sodium and potassium were measured in red blood cells. Calcium levels were 21% higher in the hypertensive subjects (p = 0.02), and a 9% increase in sodium was observed in an expanded sample (p = 0.04). Neither intracellular calcium nor intracellular sodium had a significant linear correlation with blood pressure when hypertensive subjects and controls were examined separately or when the two groups were combined. Potassium was slightly but not significantly increased in hypertensive subjects. Among the participants for whom both calcium and sodium measurements were available, a weak, nonsignificant correlation between these ions was noted (r = 0.2; n = 48). This correlation was significant among participants in the control group examined separately (r = 0.3; n = 33; p = 0.05). Although the measurements were performed in different cell lines, these findings demonstrate increases in both intracellular calcium and sodium in hypertensive humans.

Adult↗
PubMed1987

Surgical treatment of infants with esophageal atresia and VATER association.

Our surgical experience in 10 infants with esophageal atresia and the VATER association of multiple congenital anomalies is reviewed. Early recognition and evaluation of the various lesions enabled the planning of a staged surgical approach with a satisfactory outcome. Seven of the patients survived. There were no immediate postoperative deaths. Development and growth curves of the surviving patients are satisfactory. Despite multiple operative procedures infants with VATER association may lead a reasonably normal life.

Abnormalities, Multiple↗