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Biomedical subjects

R Heller

Publications and source records attributed to R Heller.

At least 163 records · Page 9Linked to original sources
PubMed1986

Retention of fluid and particles in the digestive tract of the llama (Lama guanacoe f. glama).

The retention times of fluid and particles of different lengths were measured in the digestive tract of the llama. PEG was used as a fluid marker; hay particles were labelled with cerium or samarium and the samples were determined by neutron activation analysis. In compartments 1 and 2 the retention time of fluid (9.7 hr) was significantly shorter than that of particles having a length of 0.2-1.0 cm (19.2 hr) and 2.5-4.0 cm (25.0 hr). In the intestine slightly significant differences in the retention times of fluid (20.1 hr) and particles (26.2 hr) were seen. In the whole digestive tract retention times were 36.2 hr for fluid, 52.0 hr for smaller particles and 59.9 hr for larger particles.

Animals↗
PubMed1985

Effect of GSH depletion by 1-chloro-2,4-dinitrobenzene on human platelet aggregation, arachidonic acid oxidative metabolism and cytoskeletal proteins.

Platelet reduced glutathione (GSH) is completely depleted by 1-chloro-2,4-dinitrobenzene (CDNB), which is a substrate for GSH-S-transferase. GSH-depleted platelets: a) aggregate normally at high inducer concentration; b) respond with increased (after arachidonic acid) or depressed (after collagen) aggregability at low inducer concentration; c) show almost no arachidonic acid-induced stimulation of the hexose monophosphate shunt; d) are sensitized to oxidant agents such as diamide, which elicits a faster cytoskeletal protein oxidative polymerization and reversible aggregation. Our results suggest that GSH acts as a reducing cofactor and/or free radical scavenger in the PG-hydroperoxidase step of the cyclooxygenase pathway; moreover, GSH protects membrane and cytoskeletal protein -SH groups from oxidation.

Arachidonic Acid↗
PubMed1985

Control of stomach motility in the llama (Lama guanacoe f. glama).

Manometric and electromyographic recordings of stomach motility were made in five conscious llamas to investigate the influence of distension of the stomach compartments, of temporary cervical vagal blockade and the influence of atropine, acetylcholine and adrenaline. The frequency of A-contractions was slowed by distension of the canal joining compartment 2 (C2) and compartment 3 (C3), or of the proximal region of C3, and either increased and/or reduced by distension of the distal region of C3 or the hind stomach. The number of B-contractions in a cycle was increased according to the degree of distension of the cranial sac of compartment 1 (C1). B-contractions were also induced by distension of the canal or proximal region of C3 and were inhibited by distension of the distal region of C3 or the hind stomach. Contractions of C3 were not influenced by distension of C1 or C2 but were inhibited by distension of the canal, while distension within C3 caused a local excitation and an inhibition both proximal and distal to the point of stimulation. The hind stomach was only affected by local stimuli. Temporary vagal blockade abolished all contractions of C1, C2, and the canal and C3, but had little effect on the motility of the hind stomach. Infusion of atropine (0.01 mg/kg), acetylcholine (7-33 micrograms/kg . min) and adrenaline (0.3 micrograms/kg . min) inhibited motility in all stomach compartments except the hind stomach where acetylcholine was stimulatory. It is concluded that while the hind stomach may have intrinsic motility, the contractions of C1, C2, the canal and C3 of the llama stomach are dependent upon a vagal motor nerve supply and that the pattern of contractions observed is regulated at least partially according to the individual degree of distension of each of the stomach compartments.

Acetylcholine↗
PubMed1985

Localization of phosphatidylethanolamine in the plasma membrane of diamide-treated human blood platelets.

In human blood platelet plasma membranes phosphatidylethanolamine (PE) is asymmetrically distributed between the two leaflets. The main part of this phospholipid is localized at the inner half of the lipid bilayer. Upon stimulation of the cell a substantial transbilayer movement of PE as well as phosphatidylserine occurs and the outer leaflet then provides a procoagulant surface. The thrombin-induced PE flip-flop is inhibited by pretreatment of platelets with diamide, whereas pretreatment of platelets with diamide alone up to 5 mM did not change considerably the localization of PE in the platelet membrane. Thus, cytoskeletal proteins, which are modified by diamide, are not involved in the maintenance of the PE asymmetry but are important for the realization of the agonist-induced events in the platelets.

Adenosine Diphosphate↗
PubMed1984

Chemical modification of cytoskeletal proteins of human blood platelets by diamide.

Incubation of human blood platelets with diamide (azo-dicarboxylic acid-bis-dimethylamide, DIA) influences the aggregation behaviour considerably. Depending on concentration and incubation time DIA induces a reversible aggregation or brings about complete inhibition. The effect is reversible and may be due to the regeneration of reduced glutathione (GSH) which will be oxidized to GSSG by DIA. DIA causes disulfide-linked polymer formation of certain cytoskeletal proteins. At least three polymer families (Pa, Pb, Pc) with different molecular weights are formed depending on dosage and incubation time of DIA. The appearance of a double band in Pa correlates with reversible aggregation, the formation of Pc is always accompanied by a complete inhibition of aggregation. A disturbance of cytoskeleton-membrane interaction by polymer formation can be assumed. GSH serves as a reductant of disulfide-linked polymers whereby a direct link between the maintenance of SH/SS status of platelets and GSH can be established.

Azo Compounds↗
PubMed1984

[Proteins and phospholipids of thrombocytes and erythrocytes in glucose-6-phosphate dehydrogenase deficient patients].

Proteins and phospholipids of platelets and red cell membranes of glucose-6-phosphate-dehydrogenase-deficient patients with chronic hemolytic disease were investigated. The enzyme deficiency is not connected with alteration in the protein and phospholipid pattern of platelets. However, marked differences in the diamide-induced protein polymerization between normal and deficient platelets were found. Whereas normal platelets show only a weak polymerization which is reversible during diamide incubation of the cells, the deficient platelets demonstrate a considerable and long lasting protein polymerization. The results point to a direct connection between the thiol-disulfide status of platelets and intracellular level of glutathione, which is able to repair oxidative damages. Two of the six patients showed already protein polymers in their erythrocyte membrane without addition of any SH-oxidizing agent. The phospholipid pattern of the deficient red-cell membranes were comparable to the controls.

Adolescent↗
PubMed1984

Family resemblances in height and relative weight in the Framingham Heart Study.

The correlations of both height and relative weight (the Quetelet Index: wt/ht2) were studied amongst adult relatives in the Framingham Heart Study. The parental generation was first examined starting in 1949 when they were aged 30-62 years. The offspring (and their spouses) were examined beginning in 1971 when they were aged 20-49 years. Thus, it was possible to compare adult levels of body size in two generations. For height there are correlations between relatives that suggest large genetic variation for adult body height. For relative weight as measured by Quetelet's Index, the associations between relatives show a pattern that is more difficult to interpret and gives little support for sizable contributions of genetic differences to the population variation in relative weight. Although there is little evidence for large genetic variation for obesity, there is marked resemblance for obesity among first-degree relatives. This fact may be used to advance the family-based approach to screening, identification and intervention on the cardiovascular complications of obesity.

Adult↗
PubMed1983

[Effectiveness of different intervention measures in children and adolescents with hypertension and lipid metabolism disorders].

141 children and adolescents (7-21 years, mean age 14.2 years) showed values of blood pressure, total cholesterol and triglycerides greater than or equal to 90 percentile and HDL-cholesterol values less than or equal to 10 during an examination of 639 children of parents with distinct coronary risk factors or early percentile infarction. By randomization they were subdivided into two groups. (A and B) and underwent intervention measures of different intensity. While group B got only a unique recommendation concerning the preventive measures, in group A a regular, non medicamentous individual treatment was performed. After one year a decrease of blood pressure could be proved in the two groups. A significant decrease of total and HDL cholesterol was found only in group A. While the blood pressure was most clearly reduced in 7-13-year-old children, the most distinct lipid changes were shown in 14-17-year-old adolescents. An influence on body-weight and triglycerides could not be established. Our results confirm the possibilities and also the limits of preventive measures in childhood and adolescence. Apart from the intended decrease of blood pressure and total cholesterol the simultaneous decrease of HDL-cholesterol refers to open questions in the conception of the primary prevention, particularly in children.

Adolescent↗
PubMed1982

Detection of adrenoleukodystrophy by increased C26:0 fatty acid levels in leukocytes.

Very long chain fatty acids of peripheral blood leukocytes were analyzed by gas chromatography in nine members of a family including two hemizygotes and one obligate heterozygote for adrenoleukodystrophy (ALD), as well as in twelve controls. Comparative investigations were done in cultured fibroblasts. Elevated C26:0 levels were observed in leukocytes and fibroblasts of ALD hemizygotes. The obligate heterozygote displayed a clear-cut increase of C26:0 concentration in leukocytes but not in fibroblasts. Determination of C26:0 in leukocytes may serve as diagnostic tool in the detection of ALD gene carriers.

Adolescent↗
PubMed1982

Marked stress hyperglycemia in a child.

A 16-month-old child is presented who developed severe "stress hyperglycemia" with the onset of a respiratory distress syndrome. The serum glucose rose from 74 mg/dl to 520 mg/dl and returned to 52 mg/dl all within 24 h. These variations in serum glucose were paralleled by a similar marked increase in plasma cortisol concentration (from 41 to 90 to 36 micrograms/dl). The patient was receiving no iv dextrose and required no exogenous insulin. These data are consistent with a diagnosis of stress hyperglycemia. This report is unique in that, to our knowledge, stress hyperglycemia to levels greater than 350 mg/dl have not been previously reported in either adults or children.

Humans↗
PubMed1982

Intergroup Hodgkin's disease in children study of stages I and II: a preliminary report.

The intergroup study of involved-field (IF) radiotherapy, IF radiotherapy plus MOPP chemotherapy, and extended-field (EF) radiotherapy for treatment of Hodgkin's disease in children has assessed 305 patients. Of these, 279 were "not ineligible" (no mediate cause for disqualification). Among 223 randomized patients, 144 were evaluable, 131 had documentation of complete or partial remission, 20 of the remitters relapsed, and two died. Among 62 nonrandomized patients with favorable presentations (unilateral upper neck, unilateral inguinal, or massive mediastinal disease), 29 had documented remission, two relapsed, and none died. Length of initial disease control (LIDC) was used to measure duration of response. LIDC was best in patients given IF plus MOPP, and 95% are disease free. EF was better than IF radiotherapy (P = 0.004). Of the disease characteristics prognostic for response (stage, histologic subtype, and presence of symptoms), only the last factor had a statistically significant effect on LIDC (P = 0.004). Ninety-six percent of the patients survive. Using criteria developed by the committee, 23% of the staging procedures reviewed were nonevaluable and 28% of the radiotherapy treatments were nonevaluable. The necessity for criteria for evaluation of staging and treatment is certain. Length of followup is too short for correlations of treatment with significant late effects and for relevant therapeutic recommendations.

Antineoplastic Agents↗
PubMed1980

Structure and organization of the highly repeated and interspersed 1.3 kb EcoRI-Bg1II sequence family in mice.

EcoRI digestion of total mouse DNA yields a prominant 1.3 kb fragment amounting to between 1 and 2% of the mouse genome. The majority of the 1.3 kb EcoRI fragments have a single Bg1II site 800 bp from one end. This EcoRI-Bg1II sequence family shows HindIII and HaeIII sequence heterogeneity. We have cloned representatives of the EcoRI-Bg1II gene family in Charon 16A and studied their structure and organization within the genome. The cloned 1.3 kb fragments show the expected restriction enzyme patterns as well as additional heterogeneity. Representatives of the EcoRI-Bg1II sequence family were found to be interspersed throughout the mouse genome as judged by CsCl density gradient centrifugation experiments. Family members were also found to be organized in higher order repeating units. Homologous sequences were also found in other rodent species including rat and Chinese hamster. Cross hybridization between a cloned 1.3 kb mouse fragment and a cloned CHO repeated sequence is of special interest since the latter has been shown to contain sequences homologous to the Human A1uI family by nucleotide sequencing.

Animals↗
PubMed1980

The recurrence risk for neural tube defects in the United States: a collaborative study.

To determine the recurrence risk for patients with one prior pregnancy affected with neural tube defects (NTD), the authors have pooled data from eight testing centers. In 831 pregnancies studied because one sib was affected with an NTD, the recurrence rate was 3.0%, with 95% confidence limits of 2.0-4.3%, and 99% confidence limits of 1.8-4.8%. The recurrent lesion, whether spina bifida or anencephaly, tended to be concordant with the first to a significant degree. Only 12.2% of recurrent NTD were different from the first, with 95% confidence limits of 4.1-26.2%, and 99% confidence limits of 1.7-30.9%. Both an accurate recurrence risk and the information that a recurrent NTD lesions tends to be concordant with that in the first affected child are useful in the genetic counseling of patients in the United States and in the selection of appropriate prenatal diagnostic studies.

Female↗
PubMed1979

Covalent binding of photosensitive 1-(12-azido-[9,10(-3)H2]oleoyl)glycero-3-phosphocholine (lysolecithin) to human serum high density apolipoproteins.

Human serum high density apoproteins were complexed with increasing concentrations of 1-(12-azido-[9,10(-3)H2]oleoyl)glycero-3-phosphocholine up to the saturation concentration (72 mol lysolecithin per mol apo HDL). Ultraviolet irradiation generated the nitrene which led to crosslinking with the two main apolipoproteins AI and AII. Methods are described for the removal of excess, unbound lipid and the column chromatographic separation of the lipopolypeptides AI and AII.

Apolipoproteins↗