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Biomedical subjects

G Nagel

Publications and source records attributed to G Nagel.

At least 109 records · Page 6Linked to original sources
PubMed1987

Na+ currents generated by the purified (Na+ + K+)-ATPase on planar lipid membranes.

Purified (Na+ + K+)-ATPase from pig kidney was attached to black lipid membranes and ATP-induced electric currents were measured as described previously by Fendler et al. ((1985) EMBO J. 4, 3079-3085). An ATP concentration jump was produced by an ultraviolet-light flash converting non-hydrolysable caged ATP to ATP. In the presence of Na+ and Mg2+ this resulted in a transient current signal. The pump current was not only ATP dependent, but also was influenced by the ATP/caged ATP ratio. It was concluded that caged ATP binds to the enzyme (and hence inhibits the signal) with a Ki of approx. 30 microM, which was confirmed by enzymatic activity studies. An ATP affinity of approx. 2 microM was determined. The addition of the protonophore 1799 and the Me+/H+ exchanger monensin made the bilayer conductive leading to a stationary pump current. The stationary current was strongly increased by the addition of K+ with a K0.5 of 700 microM. Even in the absence of K+ a stationary current could be measured, which showed two Na+-affinities: a high-affinity (K0.5 less than or equal to 1 mM) and a low-affinity (K0.5 greater than or equal to 0.2 M). In order to explain the sustained electrogenic Na+ transport during the Na+-ATPase activity, it is proposed, that Na+ can replace K+ in dephosphorylating the enzyme, but binds about 1000-times weaker than K+. The ATP requirement of the Na+-ATPase was the same (K0.5 = 2 microM) with regard to the peak currents and the stationary currents. However, for the (Na+ + K+)-ATPase the stationary currents required more ATP. The results are discussed on the basis of the Albers-Post scheme.

Adenosine Triphosphate↗
PubMed1987

Genetic heterogeneity of steroid sulfatase deficiency revealed with cDNA for human steroid sulfatase.

Three cDNA clones with inserts of 1.2-1.6 kb that reacted both with antibodies and oligonucleotides specific for steroid sulfatase were isolated from a human placental library in lambda gt11. The 5'-end of one of the inserts, STS-3, was sequenced and colinearity with the amino acid sequence of 3 peptides of steroid sulfatase encompassing 64 amino acids was demonstrated. STS-3 hybridized with 2.5, 4.6 and 6.3 kb species in poly(A)+RNA and with 2.5, 4 and 9 kb fragments of EcoRI digested human DNA. The frequency of the EcoRI fragments in DNA from females was approximately twice that in DNA from males. DNA from two patients with steroid sulfatase deficiency and X-linked ichthyosis did not hybridize with STS-3. DNA from a third patient showed a normal hybridization pattern. It is concluded that steroid sulfatase deficiency is a genetically heterogenous disorder.

Amino Acid Sequence↗
PubMed1987

Cloning of a cDNA encoding the human cation-dependent mannose 6-phosphate-specific receptor.

Complementary DNA clones for the human cation-dependent mannose 6-phosphate-specific receptor have been isolated from a human placenta library in lambda gt11. The nucleotide sequence of the 2463-base-pair cDNA insert includes a 145-base-pair 5' untranslated region, an open reading frame of 831 base pairs corresponding to 277 amino acids (Mr = 30,993), and a 1487-base-pair 3' untranslated region. The deduced amino acid sequence is colinear with that determined by amino acid sequencing of the N-terminus peptide (41 residues) and nine tryptic peptides (93 additional residues). The receptor is synthesized as a precursor with a signal peptide of 20 amino acids. The hydrophobicity profile of the receptor indicates a single membrane-spanning domain, which separates an N-terminal region containing five potential N-glycosylation sites from a C-terminal region lacking N-glycosylation sites. Thus the N-terminal (Mr = 18,299) and C-terminal (Mr less than or equal to 7648) segments of the mature receptor are assumed to be exposed to the extracytosolic and cytosolic sides of the membrane, respectively. Analysis of a panel of somatic cell (mouse-human) hybrids shows that the gene for the receptor is located on human chromosome 12.

Amino Acid Sequence↗
PubMed1987

[Staging in Hodgkin's lymphoma. Exploratory laparotomy with splenectomy].

In the present paper, 66 Studies on exploratory laparotomy with splenectomy in Hodgkin's lymphoma from Western Europe and the USA are presented in tables. This statistical compilation on 7183 laparotomies shows that the spleen was involved in 39.9% (2685 out of 6900 cases investigated), the liver in only 7.7% (446 out of 5789) and the abdominal lymph nodes were involved in 30.3% (1389 out of 4578) of the cases. Altogether, laparotomy with splenectomy led to a change in staging in 33% of the patients (1892 out of 5745). In the period from 1970 to 1986, 123 patients with Hodgkin's lymphoma were laparotomized (and also splenectomied apart from one exception) at the Surgical Division, University of Göttingen. The patients comprised 52 cases in the context of primary staging and 71 cases in the context of secondary staging. In 43 cases (35.2%) the spleen was affected, in seven cases (5.7%) the liver was affected, and there was combination with spleen involvement in each case. Infiltration of abdominal lymph nodes was shown in 38.2% (26/68). Exploratory laparotomy led to a change in stage in 46 cases (37.1%) comprising 28 improvements and 18 deteriorations. Before laparotomy, 15 patients were in stage I, 29 in stage II, 44 in stage III and 21 in stage IV. After pathological staging, 14 were in stage I, 40 were in stage II, 47 were in stage II and 19 were in stage IV. Out of the 14 patients who could not be assigned to any stage before the operation, 11 could be definitively staged afterwards. In addition, lymphography was performed in 103 patients, liver and spleen scintigraphy in 51 patients, sonography in 30 patients and computer tomography in 22 patients. In the re-examination of the lymph node situation in the retroperitoneal space, lymphography attained a specificity of 48% and a sensitivity of 71.4% with a positive prediction precision of 35.7% and a negative prediction precision of 88.8%.

Hodgkin Disease↗
PubMed1985

The respiration and calcium content of heart mitochondria from rats with vitamin D-induced cardionecrosis.

Mitochondria were isolated from the heart and skeletal muscle of rats treated with three consecutive daily doses of 100 000 i.u. of calciol (cholecalciferol; 'vitamin D3'). On the fourth day after the last dose, cardiac necrosis developed. At that time mitochondria isolated from heart displayed a 10-fold higher Ca2+ content and a 6-fold lower respiratory rate with pyruvate-plus-malate as substrate as well as with other NAD-dependent substrates. No decrease in respiratory rate with succinate as substrate was observed. EDTA (5 mM) added to the medium during the isolation procedure restored both the high respiratory rate with pyruvate + malate and the low Ca2+ content of the heart mitochondria. The addition of 1 mM-CaCl2 to the medium in which a healthy (control) rat heart had been homogenized caused the same impairment of the mitochondria as did calciol treatment of the animals. No changes of mitochondria isolated from skeletal muscle were observed in rats treated with calciol. It is concluded that the heart mitochondria in vivo fail to accumulate Ca2+ from the cardiac cell overloaded with Ca2+ as the consequence of calciol treatment. Mitochondrial Ca2+ accumulation occurs during the isolation procedure unless an appropriate amount of chelating agent is added to the homogenization medium. The implication of these findings for the biochemical sequence of events in the calciol-induced cardiac necrosis is discussed.

Animals↗
PubMed1985

A specific and sensitive determination of gamma aminobutyric acid in CSF and brain tissue by gas chromatography-mass spectrometry.

The determination of gamma-aminobutyric acid (GABA) in cerebrospinal fluid and brain extracts is described. Its heptafluorobutyryl-isobutanol derivative was measured both by electron impact and chemical ionization mass fragmentography using GABA-d6 as internal standard. The derivatization product is stable for several days. The method is sensitive (1 ng absolute in cerebrospinal fluid and 30 pg in standard GABA solutions) and specific, when chemical ionization mode is applied. Normal values of GABA are in rat brain extracts (1.40 +/- 0.32 mumol/g fresh weight) and human CSF (18.3 +/- 10.0 ng/ml).

Animals↗
PubMed1985

The effect of alpha-solanine on the active calcium transport in rat intestine.

Solanine, an alkaloid isolated from potatoes was found to inhibit active calcium transport in rat duodenum both when added to the everted intestine sacs in vitro and when given to the rats in drinking water for 12 days. The inhibition by solanine of the active calcium transport in the rat intestine was found to be noncompetitive, the inhibitory constant being 25 microM.

Animals↗
PubMed1985

Effects of an inverted position on blood pressure, pulse rate, and deep tendon reflexes of healthy young adults.

This study reports the effects of an inverted position on pulse rate, blood pressure, and deep tendon reflexes of the biceps muscle, triceps muscle, and Achilles tendon. Twenty healthy adults were used as subjects. We collected data both before and after the subjects were in the inverted position for eight minutes on a specially designed tonic labyrinthine inverted table. A significant decrease in systolic blood pressure and all tendon reflexes was observed along with a significant increase in diastolic blood pressure (p less than .05). Pulse rate showed no change. The findings indicate that the inverted position is likely to be effective for decreasing muscle tone and systolic blood pressure. Although this study used healthy subjects, the inverted position may be used as a therapeutic technique, provided the clinician monitors closely the physiological effects on patients.

Achilles Tendon↗
PubMed1984

[Chronic graft-versus-host reaction following bone marrow transplantation].

Chronic graft-versus-host reaction is reported in a 19-year-old woman who developed poikilosclerodermic skin lesions within a few months following transplantation of bone marrow donated by her brother as she had acute lymphatic leukemia. The literature and the various clinical features and cutaneous manifestations of graft-versus-host reactions are reviewed.

Adult↗
PubMed1983

In vivo comparison of the nailfold capillary diameter as determined by using the erythrocyte column and FITC-labelled albumin.

The diameter of nailfold capillaries in conventional intravital microscopy is estimated by measuring th width of the erythrocyte-columns. We determined the diameter of the fluorescence-marked microscopy in 33 capillary loops in the nailfold of 12 subjects and compared it with that of the ec-columns. 400-500 mg FITC-albumin were injected into the brachial artery through cannulas inserted for bloodgas analysis. The FITC-marked capillary lumen exceeded the width of the ec-columns of 10.8 +/- 3.0 microns by 4.2 +/- 0.7 microns or by 38% on the arteriolar side, and that of 12.0 +/- 2.7 microns by 4.6 +/- 0.8 microns (p less than 0.01), on the venular side. Venous occlusion produced a significant enlargement of the ec-columns by 13% (p less than 0.01), but no significant increase in the FITC-marked capillary lumen. The difference of 405 microns between the full capillary lumen as represented by the fluorescent plasma space and the width of the ec-columns corresponds presumably to the plasmatic zone between red cells and the vessel wall. No extravasation of FITC-HA was observed neither before nor after venous occlusion.

Adult↗
PubMed1982

Quality of breast milk: its control and preservation.

The numerous problems of bacterial contamination and proper preservation of breast milk have been examined. Both the many advantages of human milk as the optimal nourishment for the newborn baby and the extensive experiences of veterinary medicine in the handling of milk have been carefully considered. Bacterial multiplication has been studied under various storage conditions. Out of several possible procedures a simple, inexpensive, rapid and reliable dip-slide screening method for determining total bacterial colony counts is described. A clear-cut procedure for the optimal collection of breast milk is presented.

Humans↗
PubMed1979

Diurnal rhythm of active calcium transport in rat intestine.

The active calcium transport along the small intestine of adult rat was shown to exhibit daily rhythmic variations of considerable amplitude. Both the light-dark cycle and the time of food presentation acted as synchronizers of the rhythm observed.

Animals↗