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Biomedical subjects

M Steiner

Publications and source records attributed to M Steiner.

At least 199 records · Page 11Linked to original sources
PubMed1993

Neovascularization and the appearance of morphological characteristics of the blood-brain barrier in the embryonic mouse central nervous system.

Vascularization and expression of blood-brain barrier (bbb)-associated morphological characteristics during the embryonic development of the mouse central nervous system (CNS) was studied by ultrastructural analysis. At embryonic day 9 (E9) capillaries were only found in the perineural mesenchymal tissue. These capillaries showed fenestrations, and pericyte like cells (PC) were found joined to the vessel walls. Around E10 endothelial cells (EC) together with PC started invading the intraneural section. At this stage, the immigrating endothelial cells lost their fenestrations and exhibited numerous, partly extended junctional complexes, which appeared 'tight' in some places. A first intraneural anastomotic plexus was observed at E10, as evidenced by the presence of blood cells in all capillary lumens. While the number of junctional complexes remained constant in intraneural capillaries, the frequency of pinocytotic vesicles decreased significantly from E10 to E17. These findings indicate that from the first day of intraneural vascularization onwards, the morphological properties of the bbb are present in the early embryonic mouse cerebral cortex.

Animals↗
PubMed1993

Viridans streptococcal shock in bone marrow transplantation patients.

We have recognized a rapidly progressive, often fatal shock syndrome associated with viridans streptococcal sepsis following bone marrow transplantation (BMT). Of 832 patients receiving a marrow transplant at the University of Minnesota between 1976 and 1988, including 123 with viridans streptococcal bacteremia, 10 patients (8%) developed clinical shock within an average of 2 days (range 0-4 days) of their first positive blood culture. Viridans streptococcal shock occurred in patients early in the transplantation course, between 1 and 28 (median 6) days following BMT when all 10 patients were neutropenic. Six of the 10 patients died as a consequence of their shock or from subsequent complications. The most frequent (6 of 10 patients) viridans streptococcal species isolated in the shock patients was Streptococcus mitis. Of multiple factors analyzed for increased risk of developing viridans streptococcal shock, only younger patient age was significantly associated with the development of shock. Although 58% of BMT recipients with viridans streptococcal bacteremia were younger than 15 years, all 10 patients comprising the shock population were < 15 years of age (P < 0.02). We speculate that certain streptococcal strains may trigger fulminant shock in the immunocompromised BMT patient.

Adolescent↗
PubMed1993

Vitamin E: more than an antioxidant.

The effect of vitamin E on platelet function has been reviewed. Although vitamin E inhibits platelet aggregation in vitro, in vivo it has no significant effect when administered in doses up to 1200 U/day. Platelet adhesion, on the contrary, is strongly inhibited by alpha-tocopherol. Doses of 400 IU/day provide greater than 75% inhibition of platelet adhesion to a variety of adhesive proteins when tested at low shear rate in a laminar flow chamber. The antiadhesive effect of vitamin E appears to be related to a reduction in the number and size of pseudopodia upon platelet activation. This effect of vitamin E may be related to changes in fatty acylation of structural platelet proteins. Clinical studies of vitamin E supplementation in patients with thromboembolic disease are in progress.

Animals↗
PubMed1993

Postpartum factors related to mother's attraction to newborn infant odors.

Hedonic responses to a variety of infant (general body, urine, and feces) and noninfant (lotion, cheese, and spice) odorants were compared in four groups of subjects: new mothers, mothers a 1-month postpartum, and female and male nonparents. Using standard scaling procedures, subjects rated each of the odorants twice on a scale from extremely unpleasant (-20.5) to extremely pleasant (+20.5). In addition, all subjects completed a set of attitude questionnaires, and mothers also answered a childbirth questionnaire and were observed while feeding their infants.

Adult↗
PubMed1993

Identification of a protein-tyrosine phosphatase from human platelet membranes by an immobilon-based solid phase assay.

The present investigations show that a 53-kDa platelet-membrane protein is a protein tyrosine phosphatase. Identification involved a novel methodology in which membrane proteins are resolved by polyacrylamide gel electrophoresis and then transblotted to a polyvinylidene difluoride membrane surface-labeled with [32P-Tyr](Glu4.Tyr1)n. Phosphatase activity appears as clear areas in the autoradiograph of the renatured 32P Western blot. Studies using this new solid-phase system indicate that a 53-kDa platelet-membrane protein dephosphorylates [32P-Tyr](Glu4.Tyr1)n. Dephosphorylation is both time- and dose-dependent. The protein-tyrosine phosphatase antagonists orthovanadate and molybdate block dephosphorylation in a concentration-dependent manner. Inhibitors of protein serine/threonine phosphatases and of acid and alkaline phosphatases do not significantly affect enzymatic activity. The enzyme is active toward phosphotyrosyl proteins but not phosphoseryl proteins. Results from the solid-phase phosphatase assays correlate with data from standard liquid-phase studies. A Lineweaver-Burk plot gives an apparent Km of 4.3 microM and an apparent Vmax = 168 nmol P(i) transferred/min/mg for the membrane enzyme towards the 32P-labeled polymer in a liquid system. Platelet lysate was shown by the solid-phase assay to possess a protein-tyrosine phosphatase of approximately equal to 50 kDa. The tyrosine phosphatase activities associated with a placental preparation, pure recombinant protein-tyrosine phosphatase 1B, and YOPR, the product of the YOP51 gene of Yersinia enterocolitica, which contains the C235R mutation, were also visualized by this technique. However, the catalytic activity of domain 1 of the transmembrane leukocyte antigen-related protein-tyrosine phosphatase was not detected using the solid-phase assay.

Amino Acid Sequence↗
PubMed1993

Neuroendocrine probes of serotonergic function: a critical review.

Neuroendocrine probes of serotonergic function are based on the premise that serotonin (5-HT) exhibits an excitory influence on the release of certain anterior pituitary hormones and that the extent of release of these hormones following a challenge with a 5-HT agonist would provide an index of central 5-HT activity. This paper critically reviews studies published to date on healthy volunteers to assess the validity of tests of serotonergic function. Using standardized criteria, it is concluded that although extensive data is available on 5-HT-neuroendocrine probes, there is no test that is currently available that would fulfil all the proposed requirements for a test to be acceptable, although ipsapirone, m-chlorophenylpiperazine (m-CPP), and possibly fenfluramine challenge tests come very close. The rapid development and availability of more specific and stereo-selective 5-HT agonists/antagonists seem to indicate that it will not be too long before a valid neuroendocrine test for the assessment of serotonergic function emerges.

Humans↗
PubMed1993

Benign retroperitoneal fibrosis and renal cell carcinoma.

We report benign retroperitoneal fibrosis associated with renal cell carcinoma in a 56-year-old woman. Based on the preoperative evaluation and initial surgical exploration, the retroperitoneal mass was assumed to be metastatic renal cell carcinoma and chemotherapy rather than surgical resection was offered to the patient. A second opinion was sought and repeat exploration revealed a resectable cell carcinoma and retroperitoneal tissue that was pathologically benign idiopathic retroperitoneal fibrosis. This report emphasizes that a patient with an otherwise resectable primary tumor must undergo multiple, deep biopsies of retroperitoneal masses before making a presumptive diagnosis of malignant retroperitoneal fibrosis secondary to metastatic cancer.

Biopsy↗
PubMed1993

Charged amino-terminal amino acids affect the lethal capacity of Lambda lysis proteins S107 and S105.

The lysis inhibitor protein S107 and the lysis effector protein S105 start at Met codons 1 and 3 of the Lambda S gene, respectively. The antagonistic action of both proteins precisely schedules lysis by formation of a non-specific lesion in the inner membrane through which the Lambda-encoded murein transglycosylase can pass. Here, we show that the main difference between lysis-effector and lysis-inhibitor is the degree by which an energized membrane inhibits either protein from hole formation. To dissect the structural parameters responsible for intrinsic inhibition of both proteins, charged amino acids were replaced proximal to the first putative membrane-spanning region in both S proteins. Our results show that the distribution of amino-terminal charged amino acids as well as the total amino-terminal net charge of S107 and S105 influence their lethal potential. The data are interpreted in terms of a model in which the electrostatic status of the amino-terminus of both S107 and S105 is an important feature affecting their conformational change required for formation of the S-dependent hole.

Amino Acid Sequence↗
PubMed1993

The missing link in phage lysis of gram-positive bacteria: gene 14 of Bacillus subtilis phage phi 29 encodes the functional homolog of lambda S protein.

In most bacteriophages of gram-negative bacteria, the phage endolysin is released to its murein substrate through a lesion in the inner membrane. The lesion is brought about by a second phage-encoded lysis function. For the first time, we present evidence that the same strategy is elaborated by a phage of a gram-positive bacterium. Thus, there appears to be an evolutionarily conserved lysis pathway for most phages whether their host bacterium is gram negative or gram positive. Phage phi 29 gene 14, the product of which is required for efficient lysis of Bacillus subtilis, was cloned in Escherichia coli. Production of protein 14 in E. coli resulted in cell death, whereas production of protein 14 concomitantly with the phi 29 lysozyme or unrelated murein-degrading enzymes led to lysis, suggesting that membrane-bound protein 14 induces a nonspecific lesion in the cytoplasmic membrane.

Amino Acid Sequence↗
PubMed1993

Stability of borderline personality disorder.

This study examines the course of illness and stability of borderline personality disorder (BPD) in a group of inpatients seen at a two-year follow-up. The diagnosis of borderline personality disorder, as established by the use of the Diagnostic Interview for Borderlines, did not change in 39 of the 65 subjects (60%) studied. Subjects who continued to show evidence of borderline psychopathology experienced more acute episodes of illness during the follow-up period and tended to be more involved in substance abuse. Impulsiveness and young age when first psychiatric care was received significantly predicted the presence of BPD features at follow-up.

Adolescent↗
PubMed1993

Distribution of DNA in human Sertoli cell nucleoli.

For better understanding of nucleolar architecture, different techniques have been used to localize DNA within the dense fibrillar component (DF) or within the fibrillar centers (FC) by electron microscopy (EM). Since it still remains controversial which components contain DNA, we investigated the distribution of DNA in human Sertoli cells using various approaches. In situ hybridization (ISH) with human total genomic DNA as probe and the use of anti-DNA antibody were followed by immunogold detection. This allowed statistical evaluation of the signal density over individual components. The Feulgen-like osmium-ammine (OA) technique for the selective visualization of DNA was also applied. The anti-DNA antibodies detected DNA in mitochondria, in chromatin, and in the DF of the nucleolus. ISH using human total genomic DNA showed similar labeling patterns. The OA technique revealed DNA filaments in the FC and focal agglomerates of decondensed DNA within the DF. We conclude that (a) EM staining techniques that utilize colloidal gold appear to be less sensitive for DNA detection than the OA method, (b) the DF consists of different domains with different molecular composition, and (c) decondensed DNA is not necessarily confined to one particular nucleolar component.

Cell Nucleolus↗
PubMed1993

Prolonged biochemical and morphological stability of encapsulated liver cells--a new method.

In this work a new type of polyelectrolyte complex capsules is introduced as an artificial housing for liver cells. Male Wistar rat hepatocytes were encapsulated using cellulose sulphate and polydimethyldialyllammonium chloride as polyelectrolytes. Amino acid metabolism rate and urea synthesis of the cells increased over the investigation period in contrast to the decrease observed in control monolayer cultures. The encapsulated cells were morphologically characterized. The described procedure represents a sufficient method for the cultivation of living cells in mechanically stable semipermeable microcapsules.

Amino Acids↗
PubMed1993

Second primary cancer in irradiated stage I testicular seminoma.

The incidence of second primary cancer (SPC) was determined in 64 irradiated stage I testicular seminoma patients, treated and followed at the Northern Israel Oncology Center from 1968 to 1988. Seven (11%) patients developed a total of eight second cancers. The cumulative risk for developing second primary cancer at ten, 15 and 20 years following the diagnosis of seminoma was 2.5%, 5.1% and 8.9%, respectively. Two patients developed SPC within the radiation field (urinary bladder, sigmoid colon) and four patients outside the radiation field (bronchogenic cancer, thymoma, malignant melanoma, thyroid cancer). In two patients, who developed lung cancer and testicular seminoma, respectively, scatter dose from the main radiation field could not be excluded as one of the factors contributing to the SPC. Three patients died as a direct result of their SPC. It is concluded that there is a low, but significant risk of solid SPC among patients apparently cured of early stage seminoma. It will be important in future surveillance studies of stage I seminoma to assess the risk of SPC in the non-irradiated patients.

Actuarial Analysis↗