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Biomedical subjects

A Pollak

Publications and source records attributed to A Pollak.

At least 181 records · Page 10Linked to original sources
PubMed1983

Neonatal nesidioblastosis--diagnosis and preoperative management.

Two infants were admitted for severe, intractable hypoglycemia. "Fasting" tests lasting 45 and 30 minutes respectively revealed hypoglycemia with inappropriately elevated levels of plasma insulin and plasma C-peptide. Subsequently, somatostatin was infused to test the individual sensitivity of the B-cells. Basal and glucose-induced insulin and C-peptide secretion were significantly reduced. Preoperative treatment with somatostatin was introduced, which controlled the hypoglycemia. In both patients, subtotal pancreatectomy was effective in restoring normal glucose homeostasis.

Blood Glucose↗
PubMed1983

Murine metabolism and disposition of iron:adriamycin complexes.

Previous studies have reported antitumor activity and reduced cardiotoxicity for a putative 3:1 complex of iron:Adriamycin (ADR). We have studied the tissue distribution and metabolism of a wide variety of freshly prepared and lyophilized iron:ADR preparations after administration to BALB/c mice (ADR, 16 mg/kg i.v.). Tissue concentrations of ADR given without iron were initially highest in kidney and liver, and ADR fluorescence was lost from all tissues except the spleen with a t1/2 of 15 to 18 hr. ADR remained the major fluorescent species in liver and kidney from 0.5 to 72 hr after treatment. Freshly prepared iron:ADR (1:1) behaved similarly to ADR except for a slightly longer tissue t1/2 in heart, liver, and kidney. The tissue distribution of freshly prepared 2:1 and 3:1 iron:ADR was very different from that of ADR without iron; lung containing the highest concentrations of ADR fluorescence. Administration of freshly prepared 1:1, 2:1, and 3:1 iron:ADR resulted in some increase in adriamycinol in the liver, but ADR was always the major fluorescent species present. The tissue distribution of 1:1 iron:ADR that had been aged for 48 or 96 hr was similar to that of fresh 2:1 and 3:1 iron:ADR rather than ADR or fresh 1:1 iron:ADR. When lyophilized iron:ADR preparations were reconstituted and administered, the 0.5-hr tissue distribution of 0.1:1, 0.2:1, 0.25:1, and 0.33:1 iron:ADR was the same as ADR alone, but 0.5:1, 1:1, 2:1, and 3:1 iron:ADR were all accumulated primarily in the lung. Physicochemical studies confirm the production of microaggregated iron:ADR complexes and light microscopy allows visualization and sizing of these aggregates. We feel that trapping of these iron:ADR aggregates in the pulmonary vascular bed accounts for the observed dramatic alteration in tissue distribution. Light and electron microscopic studies confirm the intravascular sequestration of iron in pulmonary capillaries.

Animals↗
PubMed1983

Near-tetraploid clones in acute leukemia.

Near-tetraploid clones were observed in bone marrow (BM) samples from two patients with acute leukemia. One case had a hypotetraploid clone (model chromosome range, 88-90) characterized by two apparently identical 8:21 translocations and loss of both Y chromosomes as well as by other changes. As in aneuploid patients with only a single 8:21 translocation, the cytologic features in this case were characteristic of acute myeloid leukemia with maturation. The marrow of the second patient contained immature leukemic blasts indicative of acute myeloid leukemia. The abnormal clone in this patient contained 93 chromosomes with an extra small marker. In this case we examined BM preparations that were made by several different cytogenetic methods: "direct" and 24-hr culture (with or without methotrexate synchronization). We scanned 100 consecutive mitotic cells from each of the three preparations and found almost no variation in the incidence of abnormal metaphase cells. However, in this particular case, we noted some disparity between preparations with respect to the quality of diploid mitoses versus that of near-tetraploid mitoses. This finding is discussed with near-tetraploid mitoses. This finding is discussed with regard to bias in selecting metaphase cells for banding analysis in acute leukemia in general. In both of our patients there was a close correlation between the incidence of polyploid mitoses observed in cytogenetic preparations and the incidence of bizarre blast cells found in BM smears on the same date.

Adult↗
PubMed1983

Variation amongst K562 cell cultures.

K562 cell cultures were obtained from three laboratories (A, B and C) outside our institution, and were designated according to source as K562A, K562B or K562C. The cultures obtained were constitutive or "wild type" K562 cell cultures, not cloned sublines. These cell cultures were compared with respect to growth kinetics, cell surface protein markers, surface antigens, cytogenetics and hemoglobin production. Morphology, growth kinetics in liquid suspension culture, cloning efficiency in soft agar culture, binding of anti-K562 monoclonal antibodies, and the majority of cell surface proteins were generally similar. In contrast, several important differences were observed: (1) hemoglobin synthesis induced by hemin was significantly different among K562A, B and C, K562A being most sensitive (P less than 0.05); (2) whereas more than 90% of K562A or C cells appeared to be Philadelphia chromosome (Ph1)-positive, less than 15% of K562B cells contained a Ph1; (3) membrane proteins (93 and 85 kilodalton) were identified in K562A, whereas only the 93 kilodalton protein was detected in K562B and neither of the proteins were detected in K562C. Our results indicate that K562 cells maintained in different laboratories can undergo tangible changes which may influence experimental results obtained in studies using these cells.

Autoradiography↗
PubMed1982

[Interacting between amyloid P and connective tissue proteins ].

In order to look for the position of amyloid P in the macromolecular connective tissue and extracellular matrix system, we performed binding studies involving affinity chromatography. Binding studies revealed the strong binding of fibronectin to amyloid P (S-AP). The fibronectin-amyloid P linkage was dissociated after elution with 2 M urea. Heparan sulfate, a major glycosaminoglycan of the extracellular matrix, showed strong binding to S-AP, which was dissociated at 3 M urea. Laminin, collagen type I and type IV, reduced and alkylated glomerular basement membranes as well as the glycosamino-glycans hyaluronic acid and chondroitin-4-sulfate failed to bind to S-AP. Our binding studies show that amyloid P can react strongly with extra cellular matrix proteins and can help to explain the presence of amyloid P in normal connective tissue.

Amyloid↗
PubMed1982

[Glucose disposal in very low birth weight infants ].

Glucose disposal was studied in six very low birth weight infants (birth weight 1093 +/- 67 g (M +/- SEM), gestational age 29.8 +/- 0.6 weeks, postnatal age 5.2 +/- 0.9 days) by constant infusion steady state technique. All babies required artificial ventilation because of respiratory distress syndrome (four) or aspiration pneumonia (two). Nine healthy prematures of comparable birth weight, gestational age, and postnatal age formed the control group. During a constant glucose infusion at a rate of 8 mg/kg/min (7.7 +/- 0.2) mean blood glucose levels of the sick infants were higher than the corresponding control values. All sick babies had glycosuria (glucose excretion 34 +/- 19 mg/kg/hr compared to none of the controls 0.8 +/- 0.2, p less than 0.01). Glucose disposal in the sick prematures was significantly decreased in comparison to the healthy infants [92.6% (78.7 to 99.3%) of input rate vs. 99.8% (99.7 to 99.9%), p less than 0.01]. It is concluded that sick very low birth weight infants tend to develop hyperglycemia, glucosuria, impaired glucose disposal, and renal caloric wasting when exogenous glucose is supplied at a rate of 8 mg/kg/min, which is usually well tolerated by healthy prematures.

Blood Glucose↗
PubMed1982

[Association between the glomerular basement membrane and fibronectin as revealed by affinity chromatography ].

Though there is sufficient evidence that fibronectin is an integral extracellular matrix protein of the normal human kidney, the distribution and the interaction with structural proteins of the kidney have not been resolved. There are disagreements between investigators whether fibronectin is a component of the glomerular basement membrane or linked to it. We have been examining the interaction between the glomerular basement membrane and its components type IV collagen and laminin and fibronectin. Applying affinity chromatography we detected significant interaction between collagen type IV and laminin, and fibronectin on the other hand. The noncovalent interaction between collagen type IV and fibronectin was reversible after elution with 2 M urea, the association between laminin and fibronectin was even stronger and reversible applying 3 M urea for elution. The glomerular basement membrane-fibronectin interaction reflected the laminin pattern though minor binding sites at 1 M urea and 2 M urea could be detected. These interaction studies showed the chemical and thermodynamical possibilities and probability of the glomerular basement membrane and fibronectin linkage.

Basement Membrane↗
PubMed1982

[Thyroid function in healthy premature infants and in premature infants with the hyaline membrane syndrome ].

The serum concentrations of thyrotropin (TSH), thyroxine (T4), trijodothyronine (T3) and of 3,3',5', trijodothyronine (reverse T3, rT3) were followed up during the first 4 weeks of life in 5 healthy premature infants and in 6 premature infants with hyaline membrane syndrome and artificial ventilation. TSH and T4 concentrations remained unchanged in both groups. T3 levels increased during the observation period and were significantly lower in the sick prematures on days 1 and 3 (p less than 0,02). T3 and the rT3/T3 ratio was increased in healthy and in the sick prematures, the sick prematures showing higher values, and decreased in both groups during the first week of life. We found no significant correlation between TSH and the peripheral thyroid hormone levels as well as no relation between the respiratory compliance-indicating degree of lung maturity-and the T3 or T4 concentrations. Postpartal T3 or T4 serum levels were correlated significantly with the duration of artificial ventilation. Our data indicate that a "low T3 syndrome" was present in all prematures after birth and that respiratory distress syndrome increased conversion of T4 to rT3. From our results we cannot conclude that substitution therapy with thyroid hormones may be useful in premature infants with the hyaline membrane syndrome.

Humans↗
PubMed1982

Glycosylation of glomerular basement membrane in Type 1 (insulin-dependent) diabetic children.

Immunoelectrophoresis of glomerular basement membrane antigens in the urine of 20 Type 1 (insulin-dependent) diabetic and 10 healthy children was performed. In 10 of the diabetic children, there was altered alpha-1-mobility, while the other diabetic and normal children showed alpha-2-mobility. After incubation with glucose, glomerular basement membrane antigens in the urine of healthy children showed alpha-1-mobility. Isolated human kidney glomerular basement membrane split products obtained by proteolytic degradation (papain, trypsin, chymotrypsin) were also investigated by immunoelectrophoresis. A difference was observed in the immunoelectrophoretic pattern of native and glycosylated glomerular basement membrane split products. A distinct increase of thiobarbituric acid assay positive glomerular basement membrane structures after incubation with glucose provides suggestive evidence for the occurrence of non-enzymatic glycosylation of glomerular basement membrane proteins. Glycosylated glomerular basement membrane proteins may contribute to both functional and morphological changes in diabetic glomerulosclerosis.

Adolescent↗
PubMed1982

Disappearance of bowel gas in newborn infants on mechanical ventilation.

Loss of bowel gas was observed in 18 out of 49 neonates on mechanical ventilation (37%). Its occurrence was correlated to the outcome and to the use of sedative or neuromuscular paralysing drugs. None of the babies had gastrointestinal disorders requiring surgical intervention. A gasless abdomen was found in 6 our of 26 surviving neonates (23%) and in 12 out of 23 neonates (52%) not surviving the respiratory illness. Absence of intestinal gas in unsedated or unparalysed babies (23%) as well as in Alodan treated babies (19%) was found with nearly equal frequency whereas its occurrence after neuromuscular paralysation with Alloferin was significantly higher (91%). Disappearance of intestinal gas pattern despite, normal gastrointestinal patency, occurring in mechanically ventilated neonates severely affected by respiratory distress of varying origin of after neuromuscular drug paralysation should be recognized.

Gases↗
PubMed1982

Elevation of serum lipids after chronic administration of amiodarone in rabbits.

Amiodarone hydrochloride is a potent, iodine-containing antiarrhythmic compound with a long elimination half-life, whose cardiac action appears to be mediated through an interference with thyroxine-dependent pathways in the heart. Whether it has any effect on lipid metabolism is not known. Its effect (20 mg/kg per day intraperitoneally) after 3 and 6 weeks of treatment on changes in serum lipoproteins were studied in male New Zealand white rabbits. Serum amiodarone levels reached a steady state (approximately 0.05 microgram/ml) after 3 weeks, and serum reverse T3 (an index of drug dose and duration of treatment) increased 3-4 fold by 3 and 6 weeks. In two discrete sets of studies, serum triglyceride (TG) and total cholesterol (CHOL) increased significantly (P less than 0.01) after 3 and 6 weeks on amiodarone when compared to the values in a control series of animals. Phospholipid (PL) levels were not changed. Very low density lipoproteins (VLDL) in the drug-treated groups showed a significant increase in triglyceride (P less than 0.01) and in apoprotein B (P less than 0.05). There was no change in low density lipoprotein-apoprotein B levels. Whether the abnormalities observed in serum lipids induced by amiodarone are mediated through changes in thyroid hormones or occur as a result of a direct effect on lipid metabolism is unknown, but the problem merits further investigation.

Amiodarone↗
PubMed1982

Reduced collagenolytic activity of rat kidneys with steptozotocin diabetes.

Collagenolytic activity of rat kidneys with streptozotocin diabetes was estimated by means of a biological collagenase assay and compared to healthy controls. Collagenolytic activity was found significantly decreased in rat kidneys with diabetes correlating with blood glucose levels (r = -0.82, p less than 0.001). Elevated blood glucose levels seem to be responsible for the inhibition. This is supported by our experiment of incubating bacterial collagenase with several carbohydrates as glucose, galactose and saccharose: glucose and galactose significantly inhibited the collagenolytic activity, while saccharose failed to inhibit the enzymatic reaction. The interpretation of the results is that glucose is able to bind to the enzyme as Schiff base, which could be shown by tritiated sodium borohydride reduction of the Schiff base formed between collagenase and glucose. Another support of the hypothesis is that blocking of the amino group of lysine at the active site either by glucose or trifluoroacetylation of collagenase is reducing the collagenolytic activity. The biological significance could be the decreased catabolism of collageneous material of the extracellular matrix, as, e.g., the glomerular basement membrane, which was reported in a previous publication.

Animals↗
PubMed1982

Respiratory compliance of newborns after birth and its prognostic value for the course and outcome of respiratory disease.

The compliance of the respiratory system was determined at an average of 2.89 h (range 45 min - 8 h) after birth in 82 newborns who were retrospectively divided into group 1: healthy newborns (mean gestational age 37.1 weeks, range 30 - 41 weeks); group 2: newborns with respiratory distress (RD) needing no ventilatory support (mean gestational age 37.3 weeks, range 35--40 weeks); group 3: newborns with RD needing ventilatory support and surviving (mean gestational age 34.3 weeks, range 30--39 weeks), and group 4: newborns with RD who needed ventilatory support and died (mean gestational age 30.8 weeks, range 28--37 weeks). Respiratory compliance was measured by the airway occlusion technique in spontaneously breathing babies and by injecting a known volume of gas into the closed airway system and measuring airway pressure in intubated babies. The difference in postnatal compliance was statistically significant (p less than 0.01) in those four groups and was correlated with the severity of the disease in groups 2 and 3. In infants with RD, compliance was highly predictive for the need for ventilatory support (93% correct and 7% erroneous) and in infants with ventilatory support, for the mortality (83% correct and 17% erroneous). We conclude that postnatal compliance measurements are very useful to predict the course and outcome as well as to classify the severity of RD.

Gestational Age↗
PubMed1982

[Reduced susceptibility of nonenzymatically glucosylated peptides against proteolytic cleavage (author's transl)].

Two peptides, alpha-endorphin and beta-melanocyte stimulating hormone, were nonenzymatically glucosylated, degraded by several proteolytic enzymes and the susceptibility against proteolytic enzymes compared to the peptides in the native, nonglucosylated state. Glucosylation was controlled by thin layer chromatography revealing Rf differences between the native and glucosylated peptides. Quantitative estimation of peptides was performed applying high performance liquid chromatography. The results showed reduced susceptibility of nonenzymatically glucosylated peptides to the proteolytic enzymes (papain, chymotrypsin, trypsin and papain) applied.

Chromatography, Thin Layer↗
PubMed1982

Reduced susceptibility of glycosylated hemoglobin to proteolytic cleavage.

Four different experimental designs were selected to study, whether glycosylation of hemoglobin alters susceptibility against proteolytic degradation. We compared the resistance of different hemoglobin fractions against degradation by pure proteolytic enzymes, by liver cell culture, by live organ culture and the resistance of in vitro glycosylated vs. "non-glycosylated" hemoglobin solutions. The hemolysates were characterized by high performance liquid chromatography. The degree of glycosylation of hemoglobin was further estimated by the thiobarbituric-acid assay. From the data presented it is concluded, that the glucose moiety linked to the N-terminal valine and lysine residues of the alpha- and beta chain of the hemoglobin exerts a protective effect against proteolytic cleavage. This could explain the extended lag phase in response of glycosylated hemoglobin to an improved metabolic control in diabetic patients and the discrepancy between the rate of synthesis and the rate of catabolism.

Animals↗
PubMed1982

[The infant of the diabetic mother. A current reevaluation (author's transl)].

In the past fifteen years several aspects of the diabetogenic fetopathia have changed. Tight metabolic control during pregnancy approaching normoglycemia was followed by a continuous decline in perinatal mortality. However, the evaluation of pregnancy outcome beyond statistical analyses still reveals some pertinent questions: They state to the increased incidence of congenital malformations, the pre- and postnatal diagnosis of significant gestational diabetes, the heterogeneity of impaired intrauterine growth and development and the late outcome of these children.

Congenital Abnormalities↗