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Biomedical subjects

E Winkler

Publications and source records attributed to E Winkler.

At least 55 records · Page 3Linked to original sources
PubMed1992

Derivatives of 1-beta-D-ribofuranosylbenzimidazole 3',5'-phosphate that mimic the actions of adenosine 3',5'-phosphate (cAMP) and guanosine 3',5'-phosphate (cGMP).

A series of new analogues of 1-beta-D-ribofuranosylbenzimidazole 3',5'-phosphate (cBIMP) has been designed according to the properties predicted by the MNDO method, and synthesised from substituted benzimidazoles. Dipole vectors and HOMO and LUMO energies for each benzimidazole base were calculated by the MNDO method and the lipophilicities of the cBIMP derivatives were determined. In general, the cBIMP derivatives activate cAMP-dependent protein kinases I and II and preferentially bind to site B, especially for the type II kinase, with 2-trifluoromethyl-cBIMP and 5,6-difluoro-cBIMP exhibiting the highest site selectivity. Each cBIMP derivative can stimulate cGMP-stimulated cyclic phosphodiesterase (cGS-PDE), with 5,6-dimethyl-cBIMP being as potent as cGMP, and also inhibit cGMP-inhibited phosphodiesterase (cGI-PDE). Only the 2-trifluoromethyl-cBIMP and the Rp-phosphorothioates (cBIMPS) (equatorial P = S) were resistant to hydrolysis by cPDE. The Sp-phosphorothioates were hydrolysed slowly, if at all. In addition to exhibiting a high lipophilicity, the most active compounds for the induction of apoptosis and inhibition of proliferation were also resistant to cPDE (Sp-5,6-dichloro-cBIMPS) and/or were potent activators of cAMP-dependent protein kinase (5,6-dichloro-cBIMP).

Animals↗
PubMed1992

Mapping of the epitope/paratope interactions of a monoclonal antibody directed against adenosine 3',5'-monophosphate.

A series of systematically modified cyclic AMP (cAMP) analogues, including newly synthesized benzimidazole ribofuranosyl 3',5'-monophosphates was used to map the essential molecular interactions between cAMP and the monoclonal antibody 4/2C2 (mab 4/2C2) directed against 2'-O-succinoyl cAMP [Colling, Gilles, Nass, Moka & Jaenicke (1988) Second Messengers Phosphoproteins 12, 123-133]. Its paratope binds the purine base in syn conformation by dipole-dipole interactions and hydrophobic forces and/or stacking interactions. The ribose phosphate moiety is recognized by a combination of charge interactions and H-bonds to the exocyclic and the 5'-oxygen atoms and a hydrophobic interaction at the 2'-position. There is no regioselectivity for the exocyclic oxygen atoms. Compared with the known types of binding, mab 4/2C2 thus shows a new combination of molecular interactions which may be the basis of its strikingly specific recognition and binding of the cyclic adenylates. On this account mab 4/2C2 may become an important tool in studies on cAMP metabolism.

Antibodies, Monoclonal↗
PubMed1992

An improved procedure for reconstitution of the uncoupling protein and in-depth analysis of H+/OH- transport.

An improved procedure for reincorporation of isolated uncoupling protein (UCP) from brown adipose tissue into phospholipid vesicles is reported and H+ uptake in K(+)-driven exchange diffusion quantitatively analyzed. UCP is isolated and reconstituted with medium-length linear-chain alkyl polyoxyethylene. In the critical step of vesicle formation, the stepwise removal of the detergent by polystyrene beads is applied. Vesicles are generated in the presence of solutes and buffers to be internalized which are then removed by gel filtration. The internal volume is about 4 microliters/mg phospholipid with a vesicle diameter of 100 nm. One vesicle contains, on average, six molecules UCP. The best results are obtained with purified egg yolk phosphatidylcholine. Addition of PtdEtn, PtdSer decreases the vesicle size and, still more, H(+)-transport activity by UCP. Asolectin completely inactivates UCP. K(+)-gradient-driven H+ uptake is 80% inhibited by external GTP and 95% by internal plus external GTP. When H+ transport is recorded externally by a pH electrode and internally by pyranine, the kinetics show no delay resulting from intervening membrane-bound H+ pools. Total H+ uptake after addition of carbonylcyanine m-chlorophenylhydrazone (CCCP) and valinomycin corresponds to the diffusion between H+ and K+ and is unchanged by GTP. The linear correlation of H(+)-transport inhibition to GTP binding demonstrates that all UCP molecules incorporated are equally active. The exchange diffusion between H+ uptake and K+ efflux is demonstrated using a K+ electrode and 86Rb measurements. Recording delta psi using 3,3'-diispropylthiadicarbocyanine shows a rapid generation of delta psi on valinomycin addition, which decreases only slightly with H+ uptake, even after addition of CCCP or gramicidin. The delta psi collapses only after addition of external K+. By demonstrating that valinomycin-induced K+ and H+ fluxes reflect relaxation into the diffusion equilibrium state, the transport rate of UCP can be evaluated as a first-order rate, VH+/CH+, in which the rate, VH+, is related to H(+)-uptake capacity, CH+. This allows quantitative comparison of transport rates independently of the variable CH+. The dependence on delta psi of H+ transport is measured by varying external K+ concentration. A virtually linear relation of the rate to the K(+)-diffusion potential is observed, although the capacity is only slightly changed. The linear VH+/delta psi relationship resembles an open-channel type of transport, but is discussed in terms of a low-activation-barrier type of carrier mechanism, in contrast to the log (VH+/delta psi) relation found for the ADP/ATP carrier with high activation barriers.

Acclimatization↗
PubMed1992

Photoaffinity labeling of the nucleotide-binding site of the uncoupling protein from hamster brown adipose tissue.

The nucleotide binding center of the uncoupling protein from brown adipose tissue (UCP) was probed by photoaffinity labeling with 8-azido-ATP. The isolated dimeric UCP in non-ionic detergent was used. 8-azido-ATP binds to UCP with a Kd = 3 microM, i.e. with an only threefold lower affinity than ATP and a maximum number of binding sites of about 12 mumol/g protein corresponding to about 1 mol/mol dimer UCP. UCP is rapidly degraded by ultraviolet radiation, and therefore only near ultraviolet and visible light can be used for photoaffinity labeling. The total covalent incorporation is shown to be dependent on the concentration of azido-ATP and on competing phospholipids. The specific, i.e. ATP-sensitive incorporation only to the binding site depends on the presence of cysteine. With CNBr cleavage the 8-azido-[gamma-32P]ATP insertion within the primary structure was located by identifying ATP-sensitive labeled peptides in SDS/PAGE. A major specific 8-azido-ATP incorporation was found by autoradiography in the smallest CNBr fragments. Identification of the radioactive peptides was difficult since 8-azido-ATP insertion causes a distinct shift in the gels from the stained peptides. Identification was possible by specific disulfide formation at the C-terminal within the UCP dimer which only removed the CB7 (CB, CNBr fragment) portion of the low-molecular-mass peptides but did not move the radioactive band. This excludes the C-terminal CB7 and identifies the labeled peptide as CB6. Also, limited tryptic cleavage of intact UCP at Lys293 did not remove the radioactivity. Cleavage of tryptophanes support localization of 8-azido-ATP between residues 173-280 which includes CB6. Solid-phase sequencing of the labeled CB6 both after serine lactone and carboxyl coupling suggest incorporation into Thr260. These results indicate that the adenine-binding site is within the third domain of the tripartite UCP structure at a putative hydrophilic channel which can be assessed both from the cytosol and matrix of mitochondria.

Adenosine Triphosphate↗
PubMed1991

Familial leg ulcers of juvenile onset.

Chronic ulceration of the legs was found in the propositus and in ten male relatives in a family of Iraqi Jews. All eleven males had juvenile onset of symptoms. Venous lesions with ulceration were found in two of the propositus' brothers and without ulceration in his three sisters. The findings suggest an autosomal dominant sex-limited genetic defect.

Adult↗
PubMed1991

Oblique facial cleft with anophthalmia in a mentally normal child.

An oro-ocular facial cleft with anophthalmia, classified as Tessier cleft no. 4, was satisfactorily corrected by a series of conservative procedures, including tube pedicle flap transfer, Z plasties, and bone grafting for orbital socket and zygomatic reconstruction. Beginning in 1975 when the patient was 4 months old, most of the reconstructions were performed before the routine tissue expansion and microsurgical tissue transfer techniques that are common today. The patient's development is normal and he is intellectually more advanced than most children his age. Correction of increasing asymmetry between growing and nongrowing regions of the skull in this young boy will probably be required.

Abnormalities, Multiple↗
PubMed1991

Fatal accidental inhalation of bromochlorodifluoromethane (Halon 1211).

Bromochlorodifluoromethane (Halon 1211) is a widely used fire extinguishing agent. Several cases of sudden death in teenagers associated with BCF abuse have been reported. BCF is used as a fire extinguisher in battle tanks. Two young previously healthy male soldiers were accidentally exposed to BCF in a battle tank. The tank driver died, but the gunner survived the event with no medial complications. It is concluded that BCF should be used in confined chambers only after the evacuation of all personnel.

Accidents, Occupational↗
PubMed1991

The management of acute cholecystitis in elderly patients.

Acute cholecystitis is a common cause of emergency room admissions in elderly patients, and may have an atypical course with serious complications and high mortality. The authors present 131 elderly patients (aged 70 and older) who were treated for acute cholecystitis. The most common complaint was right upper abdominal pain (73%), followed by fever (55%), vomiting (48%), palpable mass (22%) and jaundice (13%). Twelve per cent of the patients were in septic shock on admission. Most patients (74%) had severe concomitant disease, increasing their operative risk significantly. Patients were prepared for surgery by hydration, nasogastric drainage, and antibiotics, while imaging was performed. They were all operated on within 48 hours. The operation of choice was cholecystectomy, which was performed in 86 patients. In 45 older and high risk patients, cholecystostomy was performed. The decision to perform cholecystostomy was taken prior to the operation, and was based on the estimated operative risk. Five patients (3.8%) died postoperatively. The major cause of death was cardiovascular disorders. Major complications occurred in 14.5 per cent and minor in 23 per cent of the patients. The complication rate correlated with severe concomitant diseases and older age groups. Patients with fever and leukocytosis had a better outcome, possibly reflecting a better immunologic status. The authors conclude that aggressive preoperative preparation and judicious use of cholecystostomy as a life-saving drainage procedure can lower the mortality from acute cholecystitis in the elderly population.

Acute Disease↗
PubMed1990

Characterization of the yeast low Km cAMP-phosphodiesterase with cAMP analogues. Applications in mammalian cells that express the yeast PDE2 gene.

The essential interactions between cAMP and the yeast low Km cAMP-phosphodiesterase have been analyzed using cAMP analogues and phosphodiesterase inhibitors. cAMP specificity is conferred by hydrogen bonding at the N-6 and N-7 positions. In contrast to the other yeast phosphodiesterase, (Rp)-adenosine 3',5'-monophosphorothioate is not hydrolyzed. Eleven standard phosphodiesterase inhibitors were not highly effective. In Chinese hamster ovary (CHO) cells that express the yeast cAMP-phosphodiesterase (PDE2) gene, cAMP levels cannot be raised by cholera toxin. cAMP analogues that are efficiently hydrolyzed by the yeast cAMP-phosphodiesterase had no effect on the growth of CHO cells that express the PDE2 gene, even though they block the growth and alter the morphology of control cells. cAMP analogues that are not hydrolyzed by the yeast enzyme inhibited the growth and changed the morphology of both control and PDE2 expressing CHO cells. We have developed a method for creating cell lines in which cAMP levels can be reduced by expression of an exogenous cAMP-phosphodiesterase gene. By employing cAMP analogues that are not hydrolyzed by this phosphodiesterase, the inhibitory effects of the enzyme can be bypassed.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1990

[Occurrence of Vibrionaceae in crude and mechanically purified urban sewage; evaluation of their sensitivity to selected drugs].

The aim of this study was to ascertain whether bacteria from Vibrionaceae family are present in crude and mechanically cleaned urban sewage and what is their profile of resistance to selected chemotherapeutics. The presence in sewage of bacteria of Vibrionaceae family was proved. They constitute only small percentage of total number of bacteria. No influence of mechanical purification process of sewage on the reduction of total number of bacteria and bacteria from Vibrionaceae family was seen. The number of bacteria from Vibrionaceae family amounted to 6-9 cells per 100 ml of crude sewage and 2-16 cells per 100 ml of mechanically cleaned sewage. From samples tested the following species were isolated: non 01 V. cholerae, V. fluvialis, V. parahaemolyticus, A. hydrophila, A. caviae, A. sobria. All strains were sensitive to neomycin and nalidixic acid and with few exceptions of A. caviae strains to streptomycin, gentamicin, doxycycline and chloramphenicol .

Anti-Bacterial Agents↗
PubMed1989

The ADP/ATP carrier from yeast (AAC-2) is uniquely suited for the assignment of the binding center by photoaffinity labeling.

The ADP/ATP carrier from yeast was photoaffinity-labeled in mitochondria with 2-azido-[alpha-32P]ATP in a binding-center-specific, i.e. carboxyatractylate-sensitive, manner. After isolation, fragmentation possibilities unique for the yeast AAC-2 could be exploited to assign the insertion to a narrow range of the sequence. The CNBr fragment 115-210 contained all the incorporated label which corresponds to the second domain within the triple-domain primary structure of the AAC. With hydroxylamine cleavage directed to the Asn 171-Gly 172 site, all the label was found in the C-terminal 16 kDa fragment. Thus the 2-azido-ATP incorporation is clearly delimited to the 172-210 segment. 8-Azido-[alpha-32P]ATP could be site-specifically incorporated only in isolated AAC since it has a much lower affinity for AAC than 2-azido-ATP. The label was also exclusively found in the 172-210 region. With both forms no incorporation into the C-terminal region was found, as claimed for bovine AAC. The labeled segment contains Lys 179 and 182 which are homologous to bovine Lys 162 and 165 and which have been proposed to be in the translocation path.

Adenosine Triphosphate↗
PubMed1989

Role of cholecystostomy in the management of critically ill patients suffering from acute cholecystitis.

Between the years 1976 and 1985, 60 patients underwent cholecystostomy for acute cholecystitis in the surgical department of the Rokach hospital in Tel Aviv. The patients' average age was 73 years; 78 per cent were 70 years or older at the time of operation. The decision to perform cholecystostomy was taken before the operation which was performed as an emergency procedure for patients considered to be at high risk for cholecystectomy. Forty-six patients (77 per cent) had severe concomitant diseases, and 42 per cent of them had two or more associated diseases simultaneously. The cardiac risk index was high in most patients (90 per cent). Fifty-two patients recovered promptly after surgery. Five patients (8 per cent) developed significant postoperative complications. Three other patients (5 per cent) died of cardiovascular complications. Forty-two patients (70 per cent) underwent an elective cholecystectomy 6-8 weeks later with no further morbidity or mortality. Eleven patients who were at high risk had no further surgery. No residual stones were found in these patients and no relapse of the disease was recorded in the long term follow-up. Four patients were lost to follow-up. We conclude that cholecystostomy may still be used as an initial life saving procedure for critically ill patients with acute cholecystitis, and serves as a definitive procedure for patients considered to be at very high operative risk and who have no residual stones.

Acute Disease↗
PubMed1989

[Taybi-Rubinstein syndrome: the value of the x-ray picture].

28 cases of Taybi-Rubinstein syndrome with different radiological appearances are presented along with radiological differential diagnosis. Broadening of the distal phalanx of the thumb (68%) and great toe (64%) was the most common radiological sign followed by incomplete fissures of the distal phalanges of the thumb and first toes. Radiological examination in association with clinical signs and laboratory investigations is an essential part in the diagnosis of the Taybi-Rubinstein syndrome.

Abnormalities, Multiple↗
PubMed1989

[Postoperative behavior of parameters of intravascular lipid metabolism].

In order to investigate alterations of intravascular lipoprotein metabolism under postoperative conditions, clinical investigations and animal experiments with female Wistar rats were carried out. Total serum cholesterol, HDL-cholesterol and LDL-cholesterol are diminished in the postoperative state. In the immediate postoperative phase there is a rapid decrease of serum triglycerides. Post-heparin-lipolytic-activity is found initially enhanced whereas there is no change of triglyceride secretion rate. It is concluded that the decreased triglyceride level is the result of an elevated catabolism of triglyceride rich lipoproteins. Besides the fall of VLDL level the relative composition of VLDL changes. The quotients VLDL triglycerides/VLDL-phospholipids and VLDL-cholesterol/VLDL-phospholipids decrease under postoperative conditions.

Animals↗