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Biomedical subjects

H Schwarz

Publications and source records attributed to H Schwarz.

At least 19 recordsLinked to original sources
PubMed1992

Activation of an inducible c-FosER fusion protein causes loss of epithelial polarity and triggers epithelial-fibroblastoid cell conversion.

As a novel approach to studying the modulation of the polarized epithelial phenotype, we have expressed c-Fos and c-Myc estrogen receptor fusion proteins (c-FosER and c-MycER) in mammary epithelial cells. The hybrid proteins could be activated by estrogen for defined time periods and after the cells had achieved their fully polarized organization. Activation of c-MycER deregulated proliferation but did not affect epithelial polarity. Short-term activation of c-FosER induced the reversible loss of morphological and functional cell polarity. In contrast, long-term stimulation of c-FosER caused the cells to depolarize irreversibly, to invade collagen gels, and to undergo epithelial-fibroblastoid cell conversion. Our data suggest that Fos proteins are important in modulating the epithelial phenotype both in normal tissue development and in invasive processes.

Animals↗
PubMed1992

[A villous adenoma of the duodenum].

X-ray contrast examination of the upper gastrointestinal tract in a 73-year-old man with nocturnal heartburn demonstrated a constant filling defect in the duodenum. Gastroduodenoscopy revealed a 4 x 3 cm polypoid mucosal change of the duodenal wall adjacent to the pancreas. Histological examination of an endoscopically obtained biopsy showed a tubulovillous adenoma with severe mucosal dysplasia. The affected segment of duodenum was resected. Serial sections showed extensive focal carcinomatous degeneration of an adenoma. The postoperative course was unremarkable. At endoscopy 30 months later, when the patient was free of any symptoms, there was no macroscopic or microscopic evidence of recurrence. Experience so far indicates that villous adenoma of the duodenum should be treated by radical surgery.

Adenoma↗
PubMed1992

The lethal(1)optomotor-blind gene of Drosophila melanogaster is a major organizer of optic lobe development: isolation and characterization of the gene.

The X-chromosomal complementation unit lethal(1)optomotor-blind [l(1)omb] is defined by lack of complementation among over a dozen recessive lethal mutations that map to the omb gene locus. Mutations in l(1)omb also fail to complement viable mutations of three seemingly unrelated functions in this region: bifid (bi), manifesting defective wings, Quadroon (Qd), a semi-dominant mutation expressing abnormal tergite pigmentation, and In(1)ombH31, giving rise to a normal external morphology but with discrete defects in the optic lobes and behavior. The locus encodes a 70-kilobase primary transcript that is spliced into a 6-kilobase mature RNA. cDNAs for this transcript were isolated and sequenced and the derived amino acid sequence was analyzed. Certain features of this sequence suggest that the l(1)omb gene product is a nuclear regulatory protein. The lethal phase of various apparent null mutants was determined and found to occur mainly in the pupal stage. A large proportion of all hemizygous mutant males develop to pharate adults that eclose only rarely but can be rescued from the pupal case. These animals show a severe maldevelopment of the optic lobes. In addition they have only rudimentary wings as well as a Quadroon-like abdominal pigmentation. Thus, in the lethal mutants those parts of the body are affected for which independent viable mutations have been previously described in the omb locus, such as optomotor-blind, bifid, and Quadroon.

Amino Acid Sequence↗
PubMed1992

Transcriptional repression of band 3 and CAII in v-erbA transformed erythroblasts accounts for an important part of the leukaemic phenotype.

The v-erbA oncogene confers two prominent properties on transformed erythroblasts: a block of spontaneous differentiation and tolerance to wide variations in the pH or ionic strength of culture medium. V-erbA acts as a constitutive repressor of erythrocyte-specific gene transcription, arresting the expression of at least three different erythroid genes: the erythrocyte anion transporter (band 3), carbonic anhydrase II (CAII) and delta-aminolevulinate synthase (ALA-S). To test whether or not the v-erbA induced repression of these genes is causally related to the v-erbA induced leukaemic phenotype, we have reintroduced the genes for band 3 or CAII into transformed erythroblasts via retrovirus vectors. We show here that such erythroblasts, expressing v-erbA, require the same narrow range of medium pH and ion concentration for growth as do transformed erythroblasts lacking v-erbA, i.e. the v-erbA induced tolerance to pH variation was abrogated. The v-erbA induced differentiation block, however, remained unaffected by the re-expression of band 3 and was only slightly affected by the re-expression of CAII. Our experiments show that the two v-erbA-related 'erythroblast transformation parameters' are separable: suppression of band 3 and CAII accounts for one parameter (pH/ion tolerance), while the second parameter (differentiation block) must involve v-erbA regulation of a different set of target genes.

5-Aminolevulinate Synthetase↗
PubMed1992

Acupuncture fails to improve treatment outcome in alcoholics.

Fifty-six alcoholics (49 male, 7 female) of lower socioeconomic class attending an outpatient treatment program in Brooklyn, New York were prospectively randomized to one of three treatment group: point-specific acupuncture, sham transdermal stimulation or standard care (control). One third of the subjects reported a history of drug use in addition to alcohol. Results in this small sample showed no significant differences in attendance at Alcoholics Anonymous meetings, number of outpatients sessions attended, number of weeks in either the study or in the outpatient program, number of persons completing treatment or in the number of relapses. It is therefore concluded that in this small racially mixed sample of urban outpatient alcoholics, fixed point-specific standardized acupuncture did not improve outcome. We caution against the routine use of this treatment until more randomized controlled trials demonstrate a beneficial effect.

Acupuncture Points↗
PubMed1992

Iron(III) hydroxamate transport in Escherichia coli K-12: FhuB-mediated membrane association of the FhuC protein and negative complementation of fhuC mutants.

Iron(III) hydroxamate transport across the cytoplasmic membrane is catalyzed by the very hydrophobic FhuB protein and the membrane-associated FhuC protein, which contains typical ATP-binding domains. Interaction between the two proteins was demonstrated by immunoelectron microscopy with anti-FhuC antibodies, which showed FhuB-mediated association of FhuC with the cytoplasmic membrane. In addition, inactive FhuC derivatives carrying single amino acid replacements in the ATP-binding domains suppressed wild-type FhuC transport activity, which arose either from displacement of active FhuC from FhuB by the mutated FhuC derivatives or from the formation of mixed inactive FhuC multimers between wild-type and mutated FhuC proteins. Inactive FhuC derivatives containing internal deletions and insertions showed no phenotypic suppression, indicating conformational alterations that rendered the FhuC derivatives unable to displace wild-type FhuC. It is concluded that the physical interaction between FhuC and FhuB implies a coordinate activity of both proteins in the transport of iron(III) hydroxamates through the cytoplasmic membrane.

ATP-Binding Cassette Transporters↗
PubMed1992

[Inguinal hernia as a sequela of disordered bladder emptying?].

We examined 56 patients with hernias and 49 patients with other diseases prior to operation. They were all above 50 years of age. The urological screening examination included the patients history of the frequency of urination during night and day time, dysuria, the common risk factors (smoking, coughing, obstipation), obesity, a sonographic measurement of the prostate diameters, a sonographic evaluation of residual urine and the determination of the urinary flow rate. None of the above parameters showed a significant difference between the two groups. Surprisingly more than 60% of all men showed a pathological voiding function (either residual urine and/or a pathological flow rate). Our conclusions are: 1. Patients with inguinal hernias do not show a greater incidence of pathological bladder function than patients of the control group. The benign prostatic hypertrophy as a risk factor for the development of inguinal hernias is most questionable. 2. Because the results showed no significant difference between the two groups, a determination of residual urine prior to operation is not necessary. 3. More than 60% of the men above 50 years showed a pathological voiding function. We recommend a urological screening test for all men above 50 years of age during hospitalisation.

Aged↗
PubMed1992

[Hemorrhage-induced rupture of the pancreatic pseudocyst].

Hemorrhage from pseudocyst may be the most serious complication of chronic pancreatitis: the mortality from such hemorrhage approaches 80%. The bleeding arises from a major artery--the artery is eroded by the basic process of autodigestion, and the pseudocyst is converted into a pseudoaneurysm. The wall of the pseudoaneurysm is subjected to arterial pressure and may perforate into the peritoneal cavity, an adjacent segment of the gastrointestinal tract, or the pancreatic ductal system. Clinical signs and indications of complicated pseudocyst are sudden abdominal pain, hypotension, sudden increase in abdominal tenderness, decrease of hematocrit and sudden disappearance of the mass. Sonography, CT and angiography accurately define the bleeding lesion and greatly aid in planning operative strategy. Surgery, angiographic embolisation, or a combination of both may be employed. Transcystic arterial ligation and internal drainage of the pseudocyst or distal pancreatectomy are the operative procedures of choice and give the best results.

Diagnosis, Differential↗
PubMed1991

[HIV transmission in hospitals and office practice. Protection of patients and medical personnel].

Research has brought full knowledge of the identity of the human immunodeficiency virus (HIV) and its infective pathways. There are not enough diagnostic tools, however, to detect all HIV carriers in the first weeks and months after infection. This fact emphasizes that all patients should be assumed to be infectious for HIV and other bloodborne pathogens. A slight but certainly existent risk for all health-care workers is a reality. Information and recommendations concerning the protection of surgical personnel against acquisition of HIV while performing their duties, and protection of HIV carriers, were published in 1988 by the Union of Swiss Surgical Societies, Practicability and compliance with these infection-control precautions were checked in 1990 after two years' operation with the aid of a questionnaire. 89 valid answers from 110 Swiss hospitals (yielding a response rate of 81%), together with overall experience, allow us to evaluate the recommendations of 1988. We conclude that the risk of HIV infection after occupational exposure to blood and other body fluids, and the potential threat to the HIV carrier, can be minimized to a very high degree by acceptance of the recommended infection-control precautions. This is especially true in surgical units, emergencies and first aid.

Carrier State↗
PubMed1991

Suitability of different silver enhancement methods applied to 1 nm colloidal gold particles: an immunoelectron microscopic study.

In order to exploit the recently introduced 1 nm gold colloids in routine electron microscopic labeling experiments, an efficient enhancement step for a better visualization of this small marker is a prerequisite. Efficiency and reproducibility of enhancement as well as growth homogeneity of gold particles were evaluated for three different silver intensifying solutions: silver lactate/hydroquinone/gum arabic (Danscher, 1981), Ilford L4/Metol (Bienz et al., 1986), and the commercially available IntenSE M silver enhancement kit (Janssen Pharmaceutica). The best results were obtained by using the silver lactate/hydroquinone/gum arabic mixture. The quality of enhancement of the IntenSE M kit was considerably increased by the addition of the protective colloid gum arabic.

Bacterial Outer Membrane Proteins↗
PubMed1991

High precision immunoscanning electron microscopy using Fab fragments coupled to ultra-small colloidal gold.

Ultra-small colloidal gold (less than 1 nm), bound to Fab fragments provides the shortest practical specific marker system to date and can be used in concert with field emission scanning electron microscopes to precisely locate antigenic sites. An "in-lens" FE-SEM equipped with a highly sensitive single crystal YAG-detector for backscattered electrons, as well as the use of advanced specimen preparation techniques based on cryofixation, are among the indispensible prerequisites. A T-even type Escherichia coli bacteriophage, Tu II*-46, was chosen to study properties of the immunogold labeling system. Distinct regions on the tail fibers of this phage were labeled with Fab fragments derived from antibodies against the related phage Tu II*-6. The tail fibers are composed of pairs of homologous proteins, thus offering two identical antigenic sites at the same locus on the tail fibers. Fab fragments can be visualized in the SEM at high accelerating voltage (30 kV) without any additional marker. This permits comparison of the labeling characteristics of unmarked and colloidal gold-marked Fab fragments. Unmarked Fab fragments often bind by pairs (two singlet Fab fragments bound opposed to each other along the axis of the tail fiber). The labeling efficiency of unmarked Fab fragments was greater than that of ultra-small gold-labeled Fab fragments. Binding by pairs was not seen after labeling with ultra-small gold-Fab fragments. The conjugates used in this study exhibited one colloidal gold per Fab fragment.

Animals↗
PubMed1991

Surfactant substitution in ventilated very low birth weight infants: factors related to response types.

We investigated factors than may influence the response to surfactant substitution. Thirty-five very low birth weight infants with respiratory distress syndrome were treated with Curosurf at 3-12 h of age. From the changes in oxygenation, the therapeutic response was categorized as rapid and sustained, rapid with relapse, or poor. Phospholipids and surfactant protein A were quantified in gastric aspirate samples obtained immediately after birth. They showed that 16 infants had accelerated lung maturity, despite clinical and radiologic signs of respiratory distress syndrome. Ten of them had suffered from birth asphyxia or connatal infection. Nevertheless, 12 of these 16 infants responded rapidly to surfactant substitution. Poor response was seen in four infants with connatal infection. Of 19 infants with immature lung profile, 18 showed a rapid initial response to surfactant substitution. Dynamic compliance of the respiratory system or arterial blood pressure before substitution, the ultrastructure of the surfactant preparation, or persistence of the ductus arteriosus did not influence the response type, but fraction of inspired oxygen was higher before surfactant substitution in infants with poor response. Prognosis was related to short-term response: Of 17 infants who showed a rapid and sustained response, none died, whereas eight of 18 infants with relapse after rapid initial response or poor response died (p less than 0.05). We conclude that surfactant substitution may be beneficial not only in babies with primary surfactant deficiency but also in other pulmonary disorders that are common in very low birth weight infants. The type of response may be of prognostic value.

Biological Products↗
PubMed1991

Monoclonal antibodies to Leishmania mexicana promastigote antigens. II. Cellular localization of antigens in promastigotes and infected macrophages.

In the accompanying paper by Ilg et al., it was shown that Leishmania mexicana promastigotes covalently modify a secreted acid phosphatase and other proteins by carbohydrate epitopes characteristic for lipophosphoglycan (LPG). In this study, the reaction of the anti-LPG monoclonal antibodies (mAbs AP3 and L7.25) and of mAb L3.13, an antibody directed against an epitope present on the secreted acid phosphatase but not on LPG, with promastigotes and infected peritoneal macrophages is studied by immunofluorescence and immunoelectron microscopy. AP3 labels the surface, the flagellar pocket and intracellular structures in promastigotes, while L3.13 reacts predominantly with an antigen located in the flagellar pocket. Early after infection with promastigotes, but not amastigotes, AP3 or L7.25 transiently label epitopes at the surface of live macrophages. No L3.13-reactive material is detected at the surface of infected macrophages. In permeabilized, infected macrophages, AP3 heavily labels the surface of amastigotes and the lumen of the parasitophorous vacuole, while L3.13 reveals antigen in the flagellar pocket, intracellular vesicles of amastigotes, and components in the lumen of the parasitophorous vacuole. Possible mechanistic implications for Leishmania-macrophage interaction raised by these findings are discussed.

Animals↗
PubMed1991

[Choledochal cyst as an unexpected intraoperative finding].

In adulthood, choledochal cysts often surprisingly are discovered during cholecystectomy. Abdominal ultrasonography incorrectly identified the cyst as a dilated or septated gallbladder. Once suspected preoperatively, confirmation of the diagnosis is obtained by ultrasonography or computerized axial tomography, which define its relationship to the vascular structures in the porta. The rapidity and accuracy of ultrasonography favour its use as the initial investigative procedure. Direct cholangiography is the preferred modality for accurate definition of the type of choledochal cyst, ductal strictures, intrahepatic ductal configuration, and polypoid filling defects suggesting cholangiocarcinoma. The well known risk of development of ascending cholangitis as well as cystic cancer, mainly in the adult, indicates the excisional operation for preventing these complications. Cyst excision and Roux-en-Y hepaticojejunostomy is the definitive treatment of choice.

Adult↗
PubMed1990

Correlation of blood-brain barrier function and HT7 protein distribution in chick brain circumventricular organs.

The HT7 protein defined by a monoclonal antibody is a specific marker for chick brain endothelial cells (EMBO J., 5 (1986) 3179-3183). In this study, we have investigated the expression of this protein in the brain circumventricular organs which lack a blood-brain barrier. Using immunohistochemical techniques we found that the protein was absent from the vascular system of the pituitary, median eminence, subfornical organ, pineal gland, the organum vasculosum lamina terminalis and the layer of sinusoid blood vessels of the area postrema. In some regions of the median eminence and, more strikingly, in the pineal gland, parenchymal cells expressed the HT7 antigen. Immunoblots of proteins from brain, pituitary, pineal gland and retina showed that the antigen is very abundant in the retina. Lower amounts were present in brain and pineal gland. The glucose transporter was found to be an independent reliable marker for blood-brain barrier endothelium. In the chick brain the distribution of the biochemically distinct proteins was very similar. Using a postembedding technique we have ultrastructurally localized the HT7 protein specifically in blood-brain barrier endothelial cells. Thus, the expression of the HT7 protein and glucose transporter correlated with blood-brain barrier function.

Animals↗
PubMed1990

Pore formation associated with the tail-tip protein pb2 of bacteriophage T5.

Upon binding of bacteriophage T5 tails to purified FhuA receptor protein the tail-tip protein pb2 became extremely sensitive to trypsin and other proteases. However, when T5 tails were bound to FhuA integrated into liposomes, pb2 was found to retain some resistance to trypsin. Electron microscopic examination of tail-liposome complexes supported the idea that trypsin resistance of pb2 in such complexes was caused by insertion of the tail-tip into the liposomes. pb2 was isolated from tails by treatment with sodium dodecyl sulfate and was further purified by gel filtration using a fast protein liquid chromatography system. pb2 obtained with this procedure was most likely monomeric. It was extremely sensitive to trypsin. When reconstituted into black lipid bilayer membranes, it formed pores with an average single-channel conductance of 4.6 nanosiemens in 1 M KCl. Zero-current potential measurements showed only a very slight preference, if any, for cations over anions. The data are compatible with pb2 forming a large water-filled transmembrane channel. The functioning during infection of pb2 in cytoplasmic membrane depolarization and phage DNA uptake into the cell is discussed.

Electric Conductivity↗