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Biomedical subjects

R Schwartz

Publications and source records attributed to R Schwartz.

At least 253 records · Page 14Linked to original sources
PubMed1985

An examination of the effect of reimbursement and organizational structure on the allocation of hospice staff time.

The unique needs of the terminally ill patient may require more planning and service coordination than those of the non-terminal patient. The hospice interdisciplinary team was a response to these additional needs. This paper examines the pattern of patient care and administrative activities of paid hospice staff by hospice organizational type and demonstration status in the National Hospice Study. Data gathered over a one year period revealed that demonstration hospices, in which all allowable costs were Medicare reimbursed, spent significantly more time in general and patient related administrative activities than non-demonstration hospices, which operated within existing Medicare cost limits. Staff in demonstration home care-based hospices reported significantly longer home visits than staff in non-demonstration hospices. In both groups, home care-based hospice visits were of longer duration than those home visits conducted by staff of hospital-based hospices.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1985

Effects of hyperinsulinemia in the primate fetus.

Nonhuman primate models of gestational diabetes have produced fetopathies most similar to those of the human infant of the mother with gestational diabetes (IGDM). Fetal hyperglycemia, hyperinsulinemia, macrosomia, selective organomegaly, intrauterine death, and placental hyperplasia are hallmarks of the fetopathy of the IGDM. The chronic infusion of insulin into the fetus of a normal pregnant rhesus monkey results in fetal hyperinsulinemia with normal to low plasma metabolic substrate concentrations. Under these conditions, fetal hyperinsulinemia is sufficient to cause fetal growth and hormone changes observed in the human IGDM. Our studies provide evidence that the soft tissue hyperplasia in the fetal macrosomia syndromes in humans and nonhuman primates in which fetal hyperinsulinemia is observed is the direct result of that chronic in utero hyperinsulinemia.

Adipose Tissue↗
PubMed1985

Nonenzymatic glycosylation of erythrocytic proteins in normal and diabetic subjects. Enzymes of nucleoside and nucleotide metabolism.

A modification of the technique of Glyco-Gel affinity column chromatography has been employed to separate glycosylated proteins from nonglycosylated proteins of hemolysates. When glycosylation in hemolysates of 11 type I diabetic subjects was compared with that from 7 normal subjects, significant increases were found in glycosylation of hemoglobin (Hb) (12.1 +/- 6.0% versus 4.7 +/- 0.5%) and purine nucleoside phosphorylase (PNP) (5.3 +/- 3.0% versus 2.1 +/- 0.5%). However, no differences were found for nucleoside diphosphokinase (NDPK) (1.5 +/- 1.1% versus 1.0 +/- 0.4%) and adenylate kinase (AMPK) (0.5 +/- 0.4% versus 0.7 +/- 0.2%). Linear relationships were seen between glycosylated Hb and glycosylated PNP (r = 0.97) or glycosylated NDPK (r = 0.81). On incubation of hemolysates from normal individuals with high glucose (1500 mg/dl or 83 mM) and NaCNBH3 (20 mM), linear increases in the degrees of glycosylation were seen with time. After 18 h, the percentages of glycosylation of Hb, PNP, NDPK, and AMPK were increased from normal values to 31, 24, 11, and 3, respectively. When partially purified human erythrocytic PNP was incubated with various monosaccharides (20 mM) in the presence of NaCNBH3 for 6 h, glycosylation increases of 2-5-fold were seen in the order ribose greater than mannose greater than galactose greater than glucose.

Adenylate Kinase↗
PubMed1985

Hyperproinsulinemia in a family with a proposed defect in conversion is linked to the insulin gene.

Two previously described pedigrees with familial hyperproinsulinemia have elevated proinsulin conversion intermediates resulting from amino acid substitutions in the proinsulin molecule. In contrast, a third family with elevated levels of an apparently normal proinsulin molecule may have a defect in the converting process. To determine if the defect in this family lies in the insulin gene region, we used restriction fragment length polymorphisms adjacent to the insulin gene to examine cosegregation with hyperproinsulinemia. We demonstrate linkage of hyperproinsulinemia and the insulin gene in this family with a LOD score of 1.8, suggesting that the defect lies in or near the insulin gene. This method has wide applicability in determining whether hyperproinsulinemia or hyperinsulinemia is the result of defects at the insulin gene, and should permit the detection of new defects at or near this locus.

Alleles↗
PubMed1984

Chronic hyperinsulinemia in the fetal rhesus monkey: effects of physiologic hyperinsulinemia on fetal substrates, hormones, and hepatic enzymes.

Chronic fetal hyperinsulinemia, similar to that found in human infants of diabetic mothers, was produced in fetal rhesus monkeys during the latter third of gestation. Fetal plasma glucose and amino acid concentrations were found to be inversely logarithmically correlated with plasma insulin concentration. Fetal plasma glucagon concentrations were suppressed by hyperinsulinemia. Fetal plasma erythropoietin concentrations were increased by hyperinsulinemia in a dose/response manner. The activity of the hepatic gluconeogenic enzymes glucose-6-phosphatase and total phosphoenolpyruvate carboxykinase were reduced by hyperinsulinemia. Fatty acid synthase complex activity was, in contrast, increased by hyperinsulinemia while citrate cleavage enzyme and glucose-6-phosphate dehydrogenase were only increased when supraphysiologic hyperinsulinemia was produced. This model provides an opportunity to study the metabolic effects of hyperinsulinemia separate from those of hyperglycemia on the primate fetus, making it a useful model for the study of fetal pathologic conditions in diabetic pregnancies.

Amino Acids↗
PubMed1984

Familial hyperproinsulinemia due to a proposed defect in conversion of proinsulin to insulin.

Familial hyperproinsulinemia is a genetic disorder characterized by elevated plasma levels of proinsulin-like material. In two previously described kindreds this has been shown to be due to a structural abnormality in the proinsulin molecule. We have identified a third family with hyperproinsulinemia in which there appeared to be a different defect. The propositus, a 12-year-old girl, had borderline glucose intolerance and markedly elevated immunoreactive-insulin levels on oral glucose-tolerance testing. Gel filtration of plasma revealed that 66 per cent of circulating insulin immunoreactivity was accounted for by the proinsulin-like components. Two of four siblings, the father, and the paternal grandfather also had elevated fasting insulin immunoreactivity in the presence of normal plasma glucose concentrations and elevated levels of proinsulin-like material. In vitro tryptic digestion of plasma proinsulin-like material from an affected family member revealed that proinsulin was converted to insulin in a manner indistinguishable from that in the control. Similarly, proinsulin and insulin exhibited normal activity in a radioreceptor assay. These findings suggest that the proinsulin molecule in this family was normal and that hyperproinsulinemia was due to a defect in the conversion of proinsulin to insulin.

Adult↗
PubMed1984

Plasma immunoreactive erythropoietin in normal women studied sequentially during and after pregnancy.

Six healthy, nonanemic women with uncomplicated singleton pregnancies were sequentially studied for plasma immunoreactive erythropoietin levels, hematologic indices, and human placental lactogen. Mean group levels of erythropoietin as well as human placental lactogen were significantly increased (p less than 0.01) after 18 weeks' gestation compared to nonpregnant values (20 to 30 weeks post partum). However, individual responses of erythropoietin during pregnancy were found to be highly variable. There was a direct correlation of both maternal plasma erythropoietin and human placental lactogen with gestational age (p less than 0.001) but no detectable relation of erythropoietin with human placental lactogen levels. We speculate that the increase in erythropoietin levels during pregnancy acts as a trophic stimulus for effecting an increase in maternal red blood cell mass presumably to meet the increased metabolic (oxygen) demands of pregnancy.

Adult↗
PubMed1984

Glycoconjugates of murine tumor lines with different metastatic capacities. I. Differences in fucose utilization and in glycoprotein patterns.

Since various experimental findings point towards an important role of cell surface carbohydrates - in particular sialic acid - in cancer metastasis, the rationale of this study was to look for possible differences in carbohydrate metabolism and glycoprotein expression in well-defined related tumor lines of different metastatic capacity. The tumor lines analyzed were L5178Y E (= Eb), a low-metastasizing, methylcholanthrene-induced lymphoma of a DBA/2 mouse, and L5178Y ES (= ESb), a spontaneous high-metastatic variant thereof. A non-related, highly metastasizing tumor, MDAY-D2, and ConA-stimulated spleen cells were included in the study. These cell lines were compared for incorporation rates of various labelled carbohydrates and for glycoprotein patterns in SDS-polyacrylamide gels. Marked differences were observed in the incorporation of 3H-fucose, while the incorporation of 3H-galactose and 3H-mannose was similar in the different cell lines studied. Only the metastatic variant ESb incorporated 3H-fucose at a rate similar to that of ConA-stimulated T-cell blasts. Eb cells did not incorporate 3H-fucose while MDAY-D2 had a significantly lower 3H-fucose incorporation rate. Separation and purification of the intracellular products of 3H-fucose by gel filtration and high-voltage electrophoresis revealed in Eb cells a block in the synthesis of fucosylated glycoproteins at the step of the fucose-I-P-guanylyltransferase. No apparent defect in the fucose pathway was detectable in MDAY-D2 cells. An Eb----ESb shifted cell line regained the ability to incorporate 3H-fucose. All tumors displayed unique glycoprotein patterns in SDS-PAGE. Labelling with 3H-mannose revealed the most distinct bands, while labelling with 3H-galactose gave fewer and broader bands. Although clonal instability of metastasizing tumor variants has been frequently reported, subclones of Eb and ESb showed characteristics similar to those of the original cell lines with regard to metastatic capacity, fucose metabolism and glycoprotein expression. These results will be discussed in relation to differences in fucose metabolism and in surface expression of fucose as observed in other tumor systems consisting of high- and low-metastatic lines.

Animals↗
PubMed1984

Effect of low-molecular-weight proteins on protein (lysozyme) binding to isolated brush-border membranes of rat kidney.

Filtered proteins including the low-molecular-weight protein lysozyme are reabsorbed by the proximal tubule via adsorptive endocytosis. This process starts with binding of the protein to the brush-border membrane. The binding of 125I-labelled egg-white lysozyme (EC 3.2.1.17) to isolated brush-border membranes of rat kidney and the effect of several low-molecular weight proteins on that binding was determined. The Scatchard plot revealed a one-component binding type with a dissociation constant of 5.3 microM and 53.0 nmol/mg membrane protein for the number of binding sites. The binding of the cationic lysozyme was inhibited competitively by the addition of cationic cytochrome c to the incubation medium, while the neutral myoglobin had no effect. The anionic beta-lactoglobulin A inhibited the lysozyme binding in a noncompetitive manner. These data suggest that the binding takes place between positively charged groups of the protein molecule and negative sites on the brush-border membrane, and, the competition between the cationic cytochrome c and the cationic lysozyme for the binding sites may be responsible for the inhibitory effect of cytochrome c on renal lysozyme reabsorption. The binding step at the brush-border membrane appears to be cation-selective.

Animals↗
PubMed1984

Increased immunoreactive erythropoietin in cord serum after labor.

Since several hours of hypoxemia in fetal animals is sufficient to cause an increase in the plasma erythropoietin level and since labor may be associated with fetal hypoxemia, this study was undertaken to determine if erythropoietin levels in cord blood were higher in fetuses subjected to labor. Two groups of term (37 to 41 weeks) singleton pregnancies were compared: (1) those delivered by elective repeat cesarean section without prior labor (n = 18) and (2) those delivered vaginally (n = 23). Erythropoietin was measured by a radioimmunoassay in which a highly purified human erythropoietin (70,000 U/mg of protein) was used and which has a sensitivity limit of 4 to 5 mU/ml. The mean cord serum erythropoietin level was higher in pregnancies with labor (46 +/- 34 mU/ml, mean +/- SD) compared to those without (26 +/- 10, p less than 0.02). There were no differences between the two groups for maternal age, gestational age, birth weight, infant sex, or Apgar scores. No association of erythropoietin with either gestational age or sex was found. In 11 pregnancies without labor, comparisons were made among simultaneously obtained samples of umbilical arterial plasma, umbilical venous plasma, and mixed cord serum. Although there were no differences between umbilical arterial and umbilical venous plasma erythropoietin levels (21.3 +/- 9.3 versus 19.0 +/- 7.8 mU/ml), mixed cord serum was inexplicably higher (24.4 +/- 9.5 mU/ml, p less than 0.01). We concluded that in uncomplicated pregnancies the duration and intensity of labor are sufficient to cause an increase in the fetal erythropoietin level at delivery.

Adolescent↗
PubMed1984

Distal duplication 14q: report of three cases and further delineation of the syndrome.

Three cases of distal duplication 14q are presented. The first two cases are cousins in a kindred segregating a balanced translocation t(14;18)(q31;q23). The third case resulted from a maternal translocation t(14;18)(q24;p11). By review of these cases and those previously reported, a distal duplication 14q syndrome is further delineated. Common features include postnatal growth retardation, mental retardation, hypotonia, microcephaly, slanted palpebral fissures, ocular hypertelorism, sparse eyelashes and eyebrows, nasal dysmorphism, tented lip, micrognathia, posteriorly rotated ears, and minor skeletal anomalies.

Adult↗
PubMed1984

Magnesium absorption in human subjects from leafy vegetables, intrinsically labeled with stable 26Mg.

Collards, turnip greens, leaf lettuce, and spinach, grown in nutrient solution so that their Mg content was 80 to 90% 26Mg, were tested in ambulant male volunteers stabilized on a constant metabolic diet. The freeze-dried vegetables were incorporated in bran muffins in which the vegetables replaced part of the bran. Bran muffins without vegetables were consumed for breakfast each day. They were also used as a standard test meal to which the vegetable muffins were compared. All subjects participated in three consecutive isotope absorption tests: one of the standard test meal and two of the vegetables. The standard test was carried out after at least 30 days on the controlled diet. Subsequent tests of vegetables followed at 4-wk intervals. Each test meal contained 30 microCi 28MgCl2 and 50 mg stable 26Mg, the latter either as the intrinsic label of a test vegetable or as 26MgCl2 in solution taken with the standard bran muffins. Net absorption of both isotopes was measured to establish exchangeability and to determine relative Mg absorption from the vegetables. Exchangeability was 90% or higher from all meals tested. Relative Mg absorption was highest from collards and least from the standard test meal. Net absorption values ranged from 40 to 60%.

Feces↗