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Biomedical subjects

B Vogt

Publications and source records attributed to B Vogt.

At least 19 recordsLinked to original sources

Distinct alpha-subunit structures of human insulin receptor A and B variants determine differences in tyrosine kinase activities.

Human insulin receptor isoforms (HIR-A and -B) differ in their alpha-subunit structures which result from alternatively spliced precursor mRNAs. This structural difference causes distinct binding affinities for insulin. To determine the impact of the structural difference on receptor signaling, we characterized the tyrosine kinase activity of HIR-A and HIR-B in vitro and determined the insulin stimulated beta-subunit phosphorylation and tyrosine kinase activation in the intact cell. When 32P incorporation in beta-subunits of equal amounts of isolated HIR-A and HIR-B was measured, an increased 32P incorporation in tyrosine residues of the beta-subunit of HIR-B (2.5-fold) compared to that of HIR-A was found after in vitro insulin stimulation. This was paralleled by an increased rate of phosphorylation (2.0-fold) or poly(GluNa,Tyr 4:1). In vitro analysis of Km values for ATP were similar for HIR-A (Km = 14.3 microM +/- 3.8) and HIR-B (Km = 20.2 microM +/- 8.6), whereas the Vmax of HIR-B was significantly increased (HIR-A Vmax = 5.5 mumol/60 min micrograms-1 +/- 1.4, HIR-B Vmax = 42.5 mumol/60 min micrograms-1 +/- 19.2). HPLC analysis of tryptic beta-subunit phosphopeptides revealed identical patterns, suggesting that the difference in kinase activities is not due to an alteration of the phosphorylation-activation cascade within the beta-subunit. However, when cleavage of the alpha-subunit by short-time trypsinization was used to activate the tyrosine kinase, the differences in 32P incorporation between HIR-A and HIR-B were abolished.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

Cyclosporine in the treatment of azathioprine-induced red cell aplasia following renal transplantation.

Azathioprine, a well-known immunosuppressive agent, is used extensively in renal transplantation. There have been several case reports of pure red cell aplasia induced by this drug following a successful kidney transplant. Previous management of azathioprine-induced red cell aplasia included reduction of azathioprine dose, or treatment with cyclophosphamide. We propose the substitution of cyclosporine for azathioprine, in this clinical setting. Not only does cyclosporine allow recovery of bone marrow function, but it maintains a level of immunosuppression which stabilizes renal function in the post-transplant patient.

Adult

Subcellular distribution of GLUT 4 in the skeletal muscle of lean type 2 (non-insulin-dependent) diabetic patients in the basal state.

Insulin resistance of the skeletal muscle is a key feature of Type 2 (non-insulin-dependent) diabetes mellitus. To determine whether a decrease of glucose carrier proteins or an altered subcellular distribution of glucose transporters might contribute to the pathogenesis of the insulin resistant state, we measured glucose transporter numbers in membrane fractions of gastrocnemius muscle of 14 Type 2 diabetic patients and 16 non-diabetic control subjects under basal conditions. Cytochalasin-B binding and immunoblotting with antibodies against transporter-subtypes GLUT 1 and GLUT 4 were applied. The cytochalasin-B binding values (pmol binding sites/g muscle) found in a plasma membrane enriched fraction, high and low density membranes of both groups (diabetic patients and non-diabetic control subjects) suggested a reduced number of glucose transporters in the plasma membranes of the diabetic patients compared to the control subjects (diabetic patients: 1.47 +/- 1.01, control subjects: 3.61 +/- 2.29, p less than or equal to 0.003). There was no clear difference in cytochalasin-B binding sites in high and low density membranes of both groups (diabetic patients: high density membranes 3.76 +/- 1.82, low density membranes: 1.67 +/- 0.81; control subjects: high density membranes 5.09 +/- 1.68, low density membranes 1.45 +/- 0.90). By Western blotting analysis we determined the distribution of the glucose transporter subtypes GLUT 1 and GLUT 4 in the plasma membrane enriched fraction and low density membranes of seven patients of each group.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged

Nd:YAG laser-photocoagulation: acute electrophysiological, hemodynamic, and morphological effects in large irradiated areas.

Laser-photocoagulation (LPC) of arrhythmogenic myocardium has been reported to successfully ablate ventricular tachycardia. The purpose of this study was to investigate the acute hemodynamic and electrophysiological effect of continuous laser energy (Nd:YAG, 1060 nm) applied via a 0.4-mm quartz fiberoptic on the epicardial surface of the heart in nine dogs. A total of 51 +/- 2.3 pulses was delivered in each animal to induce homogeneous tissue necrosis. Applied energy was 12.3 +/- 2.7 J/mm2, irradiated surface measured 12.6 +/- 3.0 cm2, lesion depth was 6.3 +/- 1.2 mm (range: 5.0-8.1 mm), lesion volume was 8.1 +/- 2.8 cm3 (6.8% of left ventricular [LV] mass). After LPC, epicardial stimulation threshold significantly rose from 1.0 +/- 0.3 to 10.2 +/- 4.9 mA in the border zone to nontreated tissue and from 0.9 +/- 0.4 to 32 +/- 15.7 mA in the center of the lesions. Loss of epicardial activation in the irradiated areas could be demonstrated by epicardial mapping. Ventricular extrasystoles during LPC were seen in all dogs, ventricular tachycardia in seven, and ventricular fibrillation in two dogs. After LPC, cardiac output and LV dP/dtmax significantly decreased by 14.2% and 11.2%. LPC induced predictable homogeneous tissue edema, eosinophilic staining, contraction band necrosis, and sharp demarcated hemorrhagic border zones with a sharp electrical border zone to nontreated tissue and loss of epicardial activation. During LPC, various arrhythmogenic effects could be observed. However, no persistent arrhythmic activity developed after LPC. The results confirm the feasibility of epicardial LPC of the myocardium. Although not rested in this study, LPC of arrhythmogenic tissue may also be feasible as a treatment modality of ventricular tachycardia.

Animals

Immediate-early RNA 2.9 and early RNA 2.6 of bovine herpesvirus 1 are 3' coterminal and encode a putative zinc finger transactivator protein.

Bovine herpesvirus 1 (BHV-1) contains three major immediate-early (IE) genes involved in regulation of the productive cycle of replication. Two spliced IE RNAs, IER4.2 (4.2 kb) and IER2.9 (2.9 kb), are under the control of a single promoter; IER1.7 (1.7 kb) is transcribed from a different promoter in the opposite direction. Examining the kinetics of transcription, we found that the IER4.2/2.9 promoter was turned off at the end of the IE period. An alternative promoter became active, directing synthesis of an unspliced early RNA, ER2.6 (2.6 kb), which was colinear with the second exon of IER2.9 except for its 5' end in the intron about 10 bases upstream of the splice site. Sequence analysis revealed a single open reading frame common to IER2.9 and ER2.6 with a coding potential of 676 amino acids. The putative protein, named p135, contained a cysteine-rich zinc finger domain near the N terminus with homology to ICP0 of herpes simplex virus type 1, to protein 61 of varicella-zoster virus, to early protein 0 of pseudorabies virus, and to other viral and cellular proteins. The remaining parts of p135 exhibited only limited homology, mainly with pseudorabies virus protein 0, but the entire sequence was highly conserved between two strains of BHV-1 (K22 and Jura). The latency-related antisense transcript covered a large portion of ER2.6 excluding the zinc finger coding region. In transient expression assays, p135 activated a variety of promoters, including that for ER2.6, but repressed the IER1.7 promoter. Thus, p135 combines functional characteristics of ICP0, a strong transactivator, and of protein 61, a repressor. BHV-1 seems to have evolved a subtle mechanism to ensure the continued synthesis of p135 while turning off IER4.2, which encodes p180, the herpes simplex virus type 1 ICP4 homolog.

Amino Acid Sequence

[Axillo-femoral bypass: indications and results].

Axillofemoral bypass grafting is an accepted method for the treatment of vascular insufficiency of the lower limb. It is especially useful in high risk patients whose conditions preclude aortofemoral bypass grafting. The goal of our study is to evaluate whether the benefit of this operation outweigh the potential risks in the age group "sixty-plus". We performed 23 axillofemoral bypass grafting procedures (axillofemoral in 20, axillobifemoral in 3 cases) mainly be mean of 8 mm Dacrom prosthesis. The 30-day operative mortality rate was 8.7% and the cumulative 5-year patient survival rate was 52.2%. Overall the 1- and 5-year life table patency rate were 80% and 64%, respectively. The cumulative limb salvage was 90% and 72% at 1 and 5 years. We obtained an average reduction in Fontaine classification of 2 stages in the first year and 1.3 stages after 5 years. The comparison of the cumulative survival rate with the limb salvage rate indicates that advanced age should not be considered a contraindication to performing an axillofemoral bypass graft. The reduction in Fontaine stage means a remarkable improvement in quality of life.

Aged

[Colostomy closure after Hartmann operation: functional results].

The "Hartmann operation" for complication of acute diverticulitis or obstruction of the rectosigmoid is a safe procedure with few complications. However, it needs a second operation to reconstruct the continuity of the intestinal tract with more difficulties. The goal of our report is to show the 30-day morbidity and the late sequelae after colostomy closure with special concern to the late anorectal function. We analyzed 43 patients who underwent colostomy closure after Hartmann's procedure between 1985 and 1990. We controlled personally 35 patients after 32 months (range: 5-64 months) concerning their bowel habits, anal sphincter function (digital measure) and endoscopic anastomosis diameter. There were no deaths, but there was a 9% perioperative morbidity (1 anastomotic leak, 1 anastomotic bleeding and 2 wound infections). In the further course 2/35 patients were incontinent for gas and liquid stool. Further 3 patients lost water after coughing and had a poor sphincter rest tone. Our results demonstrates a low 30-day morbidity after reversal of Hartmann's procedure. It needs further investigation to show, if a damaged sphincter muscle or a lower rectum capacity could be responsible for these results.

Adult

The two isotypes of the human insulin receptor (HIR-A and HIR-B) follow different internalization kinetics.

Human insulin receptor (HIR) is expressed in two isoforms which differ in the C-terminal end of the alpha-subunit (HIR-A = -12 aa, HIR-B = +12 aa). We studied internalization kinetics of HIR-A and HIR-B in Rat1 fibroblasts. Internalized receptors were quantified by 125I-insulin binding after cell trypsinisation and solubilization, surface receptors were determined by 125I-insulin binding to intact cells and by chemical crosslinking with B26-125I-insulin. HIR-A and HIR-B show different kinetics of receptor internalization. While in HIR-A cells the maximum of internalization (approx. 65% of total) is reached after 10 min followed by a high recycling rate (approx. 80% of internalized receptors after 20 min), the internalization in HIR-B cells reaches a maximum (approx. 60% of total) after 15 min without detectable recycling within 30 min. The data show that the different alpha-subunits of both receptor types determine different velocities of internalization and determine whether a fast recycling occurs.

Animals

[Surgical significance of intestinal non-rotation in adults].

Intestinal non-rotation has been recognized as a cause of obstruction in neonates and children. It is very rarely seen in the adult and assumes surgical significance owing to the potential risk of midgut or ileocecal volvulus. However, it can also cause significant intermittent abdominal pain in the adult. We describe six personally observed patients with this malformation and analyze 38 case reports published in the English and German literature since 1923. We establish that in the acute symptomatic form only emergency laparotomy can provide the correct diagnosis and decrease the risk of bowel disturbance. In the chronic forms, barium studies of the whole intestinal tract reveal varying degrees of midgut malrotation and the non-rotation is confirmed in each case. Also in these forms, exploratory laparotomy with a consequent staging of the abdominal situs is to be recommended. In the operation described by Ladd the ascending colon is sutured at the colon descendens and sigmoideum. After this procedure the mesenterial pedicle is fixed and the risk of midgut torsion remains minimal. All reported cases after surgery are symptom-free.

Abdominal Pain

Altered expression of insulin receptor types A and B in the skeletal muscle of non-insulin-dependent diabetes mellitus patients.

The human insulin receptor exists in two isoforms, HIR-A and HIR-B, which are generated by alternative splicing of a primary gene transcript and differ by a 12-amino acid insertion sequence in the alpha-subunit. The two receptor isoforms bind insulin with different affinities and are differentially expressed in human tissues. We report here a tissue-specific alteration of the insulin receptor RNA splice pattern in non-insulin-dependent diabetes mellitus (NIDDM) patients. Whereas skeletal muscle of healthy individuals contains exclusively high-affinity HIR-A-encoding RNA, we consistently find low-affinity HIR-B RNA expression in NIDDM muscle tissue at levels similar to HIR-A.

Aged

The translocation of the glucose transporter sub-types GLUT1 and GLUT4 in isolated fat cells is differently regulated by phorbol esters.

Insulin stimulates glucose transport in isolated fat cells by activation of glucose transporters in the plasma membranes and through translocation of the glucose transporter sub-types GLUT4 (insulin-regulatable) and GLUT1 (HepG2 transporter). The protein kinase C-stimulating phorbol ester phorbol 12-myristate 13-acetate (PMA) is able to mimic partially the effect of insulin on glucose transport, apparently through stimulation of carrier translocation. In order to ascertain whether protein kinase C is involved in the translocation signal to both carrier sub-types, we determined the effect of PMA on the subcellular distribution of GLUT1 and GLUT4 by immunoblotting with specific antibodies directed against these transporters. Isolated rat fat cells (4 x 10(6) cells/ml) were stimulated for 20 min with insulin (6 nM) or PMA (1 nM). 3-O-Methylglucose transport was determined and plasma membranes and low-density microsomes were prepared for Western blotting. 3-O-Methylglucose transport was stimulated 8-9-fold by insulin, and 3-4-fold by PMA (basal, 5.6 +/- 2.3%; insulin, 43.6 +/- 7.3%; PMA, 18.4 +/- 4.9%, n = 9). PMA was able to increase the amount of GLUT4 in the plasma membrane fraction by 2.5(+/- 0.9)-fold (n = 6) whereas insulin stimulation was 4.4(+/- 1.7)-fold (n = 6), paralleled by a corresponding decrease of transport in the low-density microsomes (insulin, 50 +/- 5% of basal; PMA, 63 +/- 11% of basal, n = 6). Although PMA regulates the translocation of GLUT4, it has no effect on GLUT1 in the same cell fractions (increase in plasma membranes: insulin, 1.7 +/- 0.5-fold; PMA, 0.91 +/- 0.1-fold, n = 4; decrease in low-density microsomes: insulin, 53 +/- 11% of basal; PMA, 101 +/- 5% of basal, n = 4). These data are in favour of a role for protein kinase C in signal transduction to GLUT4 but not to GLUT1 in fat cells.

3-O-Methylglucose

Activation of phosphatidylinositol-3-kinase by insulin is mediated by both A and B human insulin receptor types.

Activation of a phosphatidylinositol-3-kinase (PI-3-kinase) is one of the earliest consequences of insulin binding to the receptor. The human insulin receptor exists in two isoforms which differ in the length of the alpha-subunit (HIR-A = 719 aa, HIR-B = 731 aa). To test whether both isoforms transduce an insulin signal on PI-3-kinase we used rat-1-fibroblasts expressing HIR-A or HIR-B. We found that insulin stimulates 32P incorporation into PIP through both HIR-A and HIR-B to a similar extent (approx. 8-10 fold).

Animals

Ion gradient-induced membrane translocation of model peptides.

The K+ diffusion potential-induced association of synthetic model peptides carrying a single positive charge originating from the NH2-terminal amino function with large unilamellar vesicles (LUV) consisting of phosphatidylcholine (PC) has been reported previously (de Kroon, A. I. P. M., J. de Gier, and B. de Kruijff. 1989. Biochim. Biophys. Acta. 981:371-373). To determine the vesicle localization of the associated peptides, fluorescence measurements utilizing the peptides' tryptophan residue as intrinsic fluorescent probe were performed. The application in these measurements, of vesicles that exhibit an asymmetric transbilayer distribution of brominated PC which is a quencher of tryptophan fluorescence, unequivocally demonstrated that the peptide H3N(+)-AIMLWA-Ome (AIXme+) is accumulated in the interface of the inner leaflet of the vesicle membrane in response to the valinomycin-induced K+ diffusion potential (negative inside). The relative contributions of the membrane potential (delta psi) and the pH gradient (delta pH, acidic inside) induced by the K+ diffusion potential, to the process have been assessed. An analysis of the pH and delta pH dependencies of the process demonstrated that the K+ diffusion potential-induced peptide accumulation is largely determined by a redistribution of peptide according to the transbilayer pH gradient, in agreement with a translocation across the vesicle membrane of the neutral, deprotonated form of the peptide. The general validity of the mechanism proposed for the vesicle-uptake of AIXme+ has been examined by extending the experiments to peptide analogues with a single negative charge and to peptides with two positive charges, and by investigating the effect of incorporating the acidic phospholipid cardiolipin (CL) into the LUV. The incorporation of CL appeared not to affect the K+ diffusion, potential-induced vesicle uptake of AIXme+. The peptide H3N(+)-RMLWA-Ome (RXme2+) showed a small delta pH independent fluorescence response to the delta psi upon raising the CL content of the vesicles to 25%.

Amino Acid Sequence

Na+,K(+)-ATPase activity and hormones in single nephron segments from nephrotic rats.

1. In the nephrotic syndrome the kidneys retain salt and water, which leads to oedema formation. The site of this sodium retention has been localized in the cortical collecting tubule by micropuncture studies. Whether or not this phenomenon is an intrinsic renal problem or is the consequence of changes in hormonal activities is still a matter of discussion. 2. Using the model of puromycin aminonucleoside-induced nephrotic syndrome in the rat, we measured Na+,K(+)-ATPase activity in nephron segments from control and nephrotic rats and investigated the regulatory role of aldosterone and endogenous-ouabain-displacing factor. 3. Nephrotic animals had a twofold increase in Na+,K(+)-ATPase activity in the cortical collecting tubule only (control versus nephrotic: 1065 +/- 68 versus 2081 +/- 274 pmol h-1 mm-1, P = 0.036), which was not modified by adrenalectomy and was independent of the kidney content of endogenous ouabain-displacing factor. Na+,K(+)-ATPase activity in the cortical collecting tubule correlated with the sodium balance in both control and nephrotic rats. 4. The data are consistent with the view that sodium retention in this model of the nephrotic syndrome is a primary event, i.e. an increase in sodium transport throughout the cortical collecting tubule expressed as a twofold increase in Na+,K(+)-ATPase activity which is no longer under hormonal regulation (aldosterone and endogenous ouabain-displacing factor).

Adrenalectomy

The three major immediate-early transcripts of bovine herpesvirus 1 arise from two divergent and spliced transcription units.

Among 54 transcripts expressed in a temporal cascade during lytic infection with bovine herpesvirus 1, we have previously identified three major immediate-early (IE) RNAs, IER4.2 (4.2 kb), IER2.9 (2.9 kb), and IER1.7 (1.6 to 1.8 kb depending on the virus strain) transcribed from the HindIII C genome region (U. V. Wirth, K. Gunkel, M. Engels, and M. Schwyzer, J. Virol. 63:4882-4889, 1989). Northern (RNA) blot, S1 nuclease protection, and primer extension analysis used in the present study demonstrated that all three IE transcripts were spliced and originated from two divergent transcription units with start sites located in the inverted repeat. Transcription unit 1 encoded two alternative spliced transcripts, IER4.2 and IER2.9, with a common exon 1 located at 0.797 to 0.795 map units (m.u.) and an exon 2 for IER4.2 (0.792 to 0.762 m.u.) in the inverted repeat; exon 2 for IER2.9 (0.754 to 0.738 m.u.) was located in the unique long sequence and transcribed in antisense orientation to latency-related RNA. Transcription unit 2 (0.818 to 0.836 m.u.), further characterized by cDNA cloning, encoded the spliced IER1.7 with three exons in the inverted repeat. Additional minor IE transcripts were interpreted as unspliced precursors and splicing variants. With regard to the number and layout of IE genes, bovine herpesvirus 1 occupies an intermediate position between pseudorabies virus and equine herpesvirus 1 on the one hand and varicella-zoster virus and herpes simplex virus type 1 on the other.

Animals

Staphylococci surviving intracellularly in phagocytes from patients suffering from chronic granulomatous disease are killed in vitro by antibiotics encapsulated in liposomes.

Granulocytes and monocytes/macrophages from patients suffering from chronic granulomatous disease (CGD) are ineffective in killing specific kinds of phagocytized bacteria, e.g., Staphylococcus aureus, due to decreased or lacking ability to produce reactive oxygen intermediates. Commonly used antibiotics like flucloxacillin are of limited therapeutic value, because the staphylococci are protected against their action in the interior of phagocytes. However, encapsulation of flucloxacillin into liposomes could enable its entrance into the interior of neutrophils from two CGD patients to kill phagocytized bacteria there. The effect of rifampicin against intracellular staphylococci could be similarly enhanced by liposome encapsulation. Dose-response relations and kinetics of killing of intracellular bacteria by antibiotics in the free and encapsulated form were studied under different conditions using J 774 mouse macrophages, because phagocytes from CGD patients are not available in great amounts. Preincubation of phagocytes with either antibiotic in liposomes subsequently endowed the cells with a strongly enhanced ability to kill phagocytized bacteria. Our data show that a drug which normally will not reach a phagosome can be delivered to this intracellular compartment by a liposome. A possible clinical use is discussed.

Anti-Bacterial Agents

Prevention by protein kinase C inhibitors of glucose-induced insulin-receptor tyrosine kinase resistance in rat fat cells.

Hyperglycemia causes insulin-receptor kinase (IRK) resistance in fat cells. We characterized the mechanism of IRK inhibition and studied whether it is the consequence of a glucose-induced stimulation of protein kinase C (PKC). Fat cells were incubated for 1 or 12 h in culture medium containing either a low-(5-mM) or high- (25-mM) glucose concentration. IRK was isolated, insulin binding was determined, and autophosphorylation was studied in vitro with [gamma-32P]ATP or was determined by Western blotting with anti-phosphotyrosine antibodies. Substrate phosphorylation was investigated with the artificial substrate poly(Glu80-Tyr20). Partially purified insulin receptor from rat fat cells, which were cultured under high-glucose conditions for 1 or 12 h, showed no alteration of insulin binding but a reduced insulin effect on autophosphorylation (30 +/- 7% of control) and poly(Glu80-Tyr20) phosphorylation (55.5 +/- 9% of control). Lineweaver-Burk plots of the enzyme kinetics revealed, beside a reduced Vmax, and increased KM (from 30 microM to 80 microM) for ATP of IRK from high-glucose-treated cells. Because a similar inhibition pattern was earlier found for IRK from fat cells after acute phorbol ester stimulation, we investigated whether activation of PKC might be the cause of the reduced IRK activity. We isolated PKC from the cytosol and the membrane fraction of high- and low-glucose fat cells and determined the diacylglycerol- and phospholipid-stimulated PKC activity toward the substrate histone. There was no significant change of cytosolic PKC; however, membrane-associated PKC activity was increased in high-glucose-treated cells.(ABSTRACT TRUNCATED AT 250 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine

[Functional results of Neer II type hemi-arthroplasty joint replacement of multi-fragment humerus head fractures].

Among the fractures of the proximal humerus--a typical kind of injury affecting elderly people, as well as gainfully employed patients, the comminuted and dislocated humeral head fractures have a specific position because of therapeutical reasons. By means of a retrospective analysis, a review is given of the results of 26 comminuted humeral head fractures type IV-VI according to Neer, treated with a Neer prosthesis type II at the surgical clinic of the Kantonsspital Lucerne between 1983 and 1989. Our interest is mainly concentrated on the functional results and on their correlation with biomechanical and perioperative factors. We use the fracture-classification and functional evaluation as described by Neer. For the results classified as "failures" (13 cases) the functional deficits of the glenohumeral joint mobility are essential. The scores reveal no significant correlation to the age of the patients, to the time interval between trauma and operation, as well to the duration of the postoperative physiotherapy. On the other hand the scores of patients with preoperative manipulation of the fractured joint (i.e. osteosynthesis, reduction attempts, physiotherapy) were significantly worse than those with primary prosthetic replacement. Furthermore, because of the insufficient restitution of the lever arm conditions, the implantation of the small-head component (15 mm) leads to significantly less favorable functional scores, with a corresponding radiological hyperpression in the cranial articular space. Our analysis leads to the following conclusions: 1. Under the condition of a conclusive preoperative diagnosis a primary prosthetic procedure is recommended depending on the type of fracture.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged