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Biomedical subjects

J B Weiss

Publications and source records attributed to J B Weiss.

At least 55 records · Page 3Linked to original sources
PubMed1991

Elevated endothelial-cell-stimulating angiogenic factor activity in rodent glycolytic skeletal muscles.

1. Capillary density is greater in skeletal muscles comprised of predominantly oxidative (type I) fibres than in those comprised of mainly glycolytic (type II) fibres. In order to investigate further the angiogenic mechanisms involved in muscle capillarization, endothelial-cell-stimulating angiogenic factor activities in various rodent skeletal muscles were compared. 2. Eleven untrained adult male Wistar rats were killed and the predominantly oxidative (type I) muscle,s soleus and heart, the predominantly glycolytic (type II) muscle, extensor digitorum longus, and the mixed-fibre muscle, gastrocnemius, were removed. Each sample was separately homogenized and centrifuged and the supernatants were diafiltered to isolate the low-molecular-mass fraction containing endothelial-cell-stimulating angiogenic activity. This was assayed for its ability to activate latent collagenase and was expressed as units, where 1 unit represents the percentage activation of the enzyme h-1 (mg of protein in the supernatant)-1. 3. The results (medians and ranges) demonstrated significantly greater endothelial-cell-stimulating angiogenic factor activity in extensor digitorum longus muscle (2.14 units, 0.62-2.87 units, n = 13) than in soleus (0.82 units, 0.59-1.79 units, n = 15), gastrocnemius (0.34 units, 0.28-0.40 units, n = 4) or heart (0.43 units, 0.16-0.52 units, n = 11) (P less than 0.01 for each) muscle. 4. These findings suggest that endothelial-cell-stimulating angiogenic activity in muscle is either inversely or not related to the local capillary density, which may be at or near a maximum in physiologically contracting, predominantly oxidative muscles.

Angiogenesis Inducing Agents↗
PubMed1990

Peptides from live yeast cell derivative stimulate wound healing.

Live yeast cell derivative is an alcoholic extract from yeast (Saccharomyces cerevisiae) that has previously been shown by three groups of workers to stimulate wound healing. Live yeast cell derivative is a complex mixture, and it was not known which of its many components was responsible for the biological activity. This study describes the separation and analysis of the major components, one of which is a peptide fraction that stimulates wound healing. The fraction consists of a mixture of peptides from 6000 to 17,000 d. It causes angiogenesis in a chick embryo yolk sac membrane assay and in a rabbit cornea assay, and it dramatically stimulates wound healing in the "Schilling/Hunt" wire mesh cylinder model at concentrations 25-fold lower than those required for the intact live yeast cell derivative.

Animals↗
PubMed1990

Production of endothelial cell stimulating angiogenesis factor (ESAF) by chondrocytes during in vitro cartilage calcification.

The aim of this study was to identify the stimulus for production of the latent collagenase and angiogenic activator ESAF by growth plate chondrocytes. Stimulation correlated most closely with matrix calcification. Alkaline phosphatase was necessary for calcification (and so stimulation of ESAF production) but we could find no evidence for a direct link with ESAF production. ESAF production was also stimulated by addition of preformed mineral to non-calcified cultures but was inhibited by dexamethasone. Protein synthesis was necessary for the stimulation of ESAF production by calcification, though ESAF is not itself a protein. Based on these findings we suggest that chondrocytes, at a suitable stage of maturation in the growth plate, are stimulated to produce ESAF by the proximity of crystals in the matrix. Stimulation, which may consist of the induction of an enzyme or transport protein, leads to the release of this potent activator of collagenolysis as part of the angiogenic cascade.

Alkaline Phosphatase↗
PubMed1990

Influence of local anesthetic solution on postdural puncture headache.

A total of 2,511 patients who received spinal anesthesia for cesarean delivery were observed for the development of postdural puncture headache (PDPH); 804 patients received a mixture of tetracaine and procaine, 942 received bupivacaine-glucose, and 765 received lidocaine-glucose. They were observed for the development of PDPH for a minimum of 72 h. PDPH occurred in 9.54% of patients who received lidocaine-glucose during the first 36 h compared with 7.64% of patients who received bupivacaine-glucose and 5.85% of patients who received tetracaine-procaine. The differences between all groups was statistically significant. No differences were found in the percentage of patients who ultimately required epidural blood patch for relief of symptoms after 36 h.

Adult↗
PubMed1990

The folding properties of the Escherichia coli maltose-binding protein influence its interaction with SecB in vitro.

It has been proposed that the cytoplasmic SecB protein functions as a component of the Escherichia coli protein export machinery by serving as an antifolding factor that retards folding of the precursor maltose-binding protein (preMBP) into a translocation-incompetent form. In this study, it was found that SecB directly interacts with wild-type preMBP and various mutationally altered MBP species synthesized in vitro to form a SecB-MBP complex that can be precipitated with anti-SecB serum. The association of SecB with wild-type preMBP was relatively unstable; such a complex was formed only when SecB was present cotranslationally or after denaturation of previously synthesized preMBP and was detected with only low efficiency. In marked contrast, MBP species that were defective in the ability to assume the stable conformation of wild-type preMBP or that exhibited significantly slower folding kinetics formed much more stable complexes with SecB. In one case, we demonstrated that SecB did not need to be present cotranslationally for complex formation to occur. Formation of a complex between SecB and MBP was clearly not dependent on the MBP signal peptide. However, we were unable to detect complex formation between SecB and MBP lacking virtually the entire signal peptide but having a completely intact mature moiety. This MBP species folded at a rate considerably faster than that of wild-type preMBP. The propensity of this mutant protein to assume the native conformation of mature MBP apparently precludes a stable association with SecB, whereas an MBP species lacking a signal peptide but exhibiting altered folding properties did form a complex with SecB that could be precipitated with anti-SecB serum.

ATP-Binding Cassette Transporters↗
PubMed1989

Factors influencing the in vitro translocation of the Escherichia coli maltose-binding protein.

An in vitro system has been utilized to study the translocation of newly synthesized Escherichia coli maltose-binding protein (MBP) into inverted membrane vesicles. Approximately 40% of precursor MBP (pMBP) synthesized with a wild-type signal peptide was imported into vesicles. However, MBP species with even minor alterations in the signal peptide hydrophobic core were imported into vesicles with an efficiency much lower than predicted from in vivo studies. Posttranslational import of wild-type pMBP into vesicles could be demonstrated if membranes were added after the termination of protein synthesis. However, if vesicles were present throughout the synthesis reaction, most pMBP import occurred either cotranslationally or very soon after completion of synthesis. The wild-type pMBP rapidly became incompetent for posttranslational translocation upon continued incubation in the absence of membranes, whereas pMBP species with altered folding properties remained competent for significantly longer periods. The rate of in vitro pMBP folding was affected by the nature of the signal peptide. The evidence suggests that one or more soluble factors may interact with the newly synthesized pMBP to help maintain it in a translocation-competent state and to promote its entrance into the export pathway.

ATP-Binding Cassette Transporters↗
PubMed1989

Anesthetic-related maternal mortality, 1954 to 1985.

This is a population-based study of the safety of obstetrical anesthesia in the Commonwealth of Massachusetts between 1954 and 1985. We used data collected by the state Committee on Maternal Mortality, which was founded in 1941. There were a total of 37 maternal deaths during the study period due to anesthetic-related complications. During the same time period, there were 886 maternal deaths. Thus, anesthetic-related mortality comprised 4.2% of all deaths, and the mortality rate was 1.5 per 100,000 live births between 1955 and 1964, 1.5 per 100,000 live births between 1965 and 1974, and 0.4 per 100,000 live births between 1975 and 1984. In the first decade of this study, aspiration during administration of a mask anesthetic was the primary cause of death. During the second decade, cardiovascular collapse associated with regional anesthesia was the primary cause of death. During the last decade of this study, all deaths were associated with general endotracheal anesthesia. As a result of this study and having identified the changes in the standard of care in Massachusetts that led to the reduction in maternal mortality, we offer recommendations to further improve the safety of anesthesia for childbirth in this country.

Adolescent↗
PubMed1989

Endothelial cell-stimulating angiogenesis factor in vitreous from extraretinal neovascularizations.

The presence of endothelial cell-stimulating angiogenic factor (ESAF) in diseased human vitreous humour has been established. The molecular mass and chromatographic behavior of this material and its property of activating procollagenase indicate it to be identical to the ESAF isolated from other sources. The biological activity of ESAF from human vitreous was demonstrated by its ability to induce positive responses in the rabbit corneal pocket, and in the chick chorioallantoic membrane and yolk sac membrane tests.

Angiogenesis Inducing Agents↗
PubMed1988

The antifolding activity of SecB promotes the export of the E. coli maltose-binding protein.

Evidence is presented that the E. coli secB gene encodes a soluble protein that interacts with the mature region of the precursor maltose-binding protein (MBP), and promotes MBP export by preventing premature folding of the newly synthesized polypeptide into an export-incompetent form. The interaction of SecB with MBP was indicated by the finding that synthesis of various export-defective MBP species interfered with normal protein export by limiting SecB availability. The antifolding activity of SecB was demonstrated by the following: the defect in MBP export in SecB- cells was suppressed by mutational alterations affecting MBP folding; export of a mutant MBP that is accomplished in a strictly posttranslational mode was totally blocked in SecB- cells; and the rate of folding of wild-type MBP synthesized in vitro was found to be accelerated when SecB was absent and greatly retarded when excess SecB was present.

ATP-Binding Cassette Transporters↗
PubMed1988

Bovine and human pineal glands contain substantial quantities of endothelial cell stimulating angiogenic factor.

Using a quantitative assay the amount of a low Mr endothelial cell stimulating angiogenesis factor (ESAF) has been determined in human pineal glands and bovine brain, retina, pineal gland, liver and kidney. Pineal glands contain approximately ten times as much ESAF as the retina or grey and white matter from the cerebral cortex and a hundred times as much as highly vascular tissues such as liver and kidney. The relevance of these findings to the highly vascular nature of the pineal gland is discussed.

Angiogenesis Inducing Agents↗
PubMed1988

Purified secB protein of Escherichia coli retards folding and promotes membrane translocation of the maltose-binding protein in vitro.

The efficient export of a subset of Escherichia coli envelope proteins is dependent upon the product of the secB gene. Previous studies indicated that SecB promotes the export of the periplasmic maltose-binding protein (MBP) by preventing premature folding of the precursor MBP in the cytoplasm into an export-incompetent form. In this study, SecB has been purified to homogeneity and shown to be a soluble, cytoplasmic, multimeric protein composed of identical 17-kDa subunits. SecB was required for efficient in vitro translocation of MBP into inverted membrane vesicles. The addition of purified SecB to an in vitro system prepared from SecB- cells significantly enhanced MBP translocation. The purified protein also quantitatively retarded folding of precursor MBP into a stable, protease-resistant conformation in the absence of membranes. Finally, the inclusion of excess purified SecB in a SecB+ in vitro system significantly prolonged the time in which precursor MBP remained competent for posttranslational import into membrane vesicles.

ATP-Binding Cassette Transporters↗
PubMed1988

Neovascularisation and its role in the osteoarthritic process.

In osteoarthritis angiogenesis is involved in the reinitiation of cartilage growth and mineralisation. A number of heparin binding protein growth factors have been proposed as angiogenic factors, but none of them is specific for microvessel cells. Another factor which is specific for microvessel cells, is of low molecular weight and non-profit has been called endothelial cell stimulating angiogenic factor (ESAF). ESAF has been found in significantly increased amounts in sera and synovial fluids of osteoarthritic patients and dogs. In addition to its angiogenic activity ESAF is able to activate neutral prometalloproteinases and to reactive the active enzyme-inhibitor complex. The implication of these observations in the pathogenesis of osteoarthritis is discussed.

Angiogenesis Inducing Agents↗
PubMed1988

Increased procollagenase activating angiogenic factor in the vitreous humour of oxygen treated kittens.

Previous studies have demonstrated an increase in a low molecular weight angiogenic factor (ESAF) present in the retinae of kittens with oxygen induced retinopathy. The present paper describes differences in the quantity of ESAF extracted from the vitreous humour of control and oxygen treated animals and proposes a mechanism for the induction of intravitreal neovascularisation.

Angiogenesis Inducing Agents↗
PubMed1988

[Idiopathic bi-auricular dilatation manifested by total cardiac failure. Apropos of a case confirmed by nuclear magnetic resonance].

Idiopathic bilateral atrial dilatation is extremely rare. We are reporting a case in a 79 year-old patient, presenting a picture of total cardiac insufficiency. The positive diagnosis was established by bi-dimensional sonography and right angiography. Nuclear magnetic resonance confirmed the diagnosis and specified the size of the various cavities. From a rhythm standpoint, there was an atrial fibrillation without conduction disorders. The main factor of the cardiac insufficiency seems to be a low atrio-ventricular output, since the valvular insufficiency due to annular dilatation is only a secondary factor. The etiology is unknown, but a congenital origin seems most probable without excluding the possibility of an acquired structural disorder.

Aged↗