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J Cohen

Publications and source records attributed to J Cohen.

At least 1,045 records · Page 58Linked to original sources
PubMed1990

Endothelin immunoreactivity in mice with gram-negative bacteraemia: relationship to tumour necrosis factor-alpha.

1. To investigate the role of endothelin in Gram-negative bacteraemia and the possible involvement of tumour necrosis factor-alpha in its pathophysiology, we measured plasma and tissue (lung, kidney and spleen) immunoreactive endothelin levels in Gram-negative bacteraemic mice, with and without passive immunization by anti-(tumour necrosis factor-alpha) antibody. 2. Plasma immunoreactive endothelin levels were greatly increased after the Escherichia coli injection. Pretreatment with anti-(tumour necrosis factor-alpha) antibody did not suppress elevated plasma immunoreactive endothelin levels (P greater than 0.1). 3. Lung tissue immunoreactive endothelin levels in mice were increased 16 h after the E. coli injection and were not affected by prior passive immunization with anti-(tumour necrosis factor-alpha) antibody. Immunoreactive endothelin in spleen and kidney was undetectable (less than 34 fmol/g wet weight). 4. Injection of rMu tumour necrosis factor-alpha into mice did not increase plasma immunoreactive endothelin levels. 5. Antibody to endothelin given 30 min after a 90% lethal dose challenge with E. coli did not affect mortality. 6. We conclude that the rise in plasma and tissue endothelin that occurs in Gram-negative bacteraemia is independent of tumour necrosis factor-alpha.

Animals↗
PubMed1990

A Ca2+ influx associated with exocytosis is specifically abolished in a Paramecium exocytotic mutant.

A Paramecium possesses secretory organelles called trichocysts which are docked beneath the plasma membrane awaiting an external stimulus that triggers their exocytosis. Membrane fusion is the sole event provoked by the stimulation and can therefore be studied per se. Using 3 microM aminoethyl dextran (AED; Plattner, H., H. Matt, H.Kersken, B. Haake, and R. Stürz, 1984. Exp. Cell Res. 151:6-13) as a vital secretagogue, we analyzed the movements of calcium (Ca2+) during the discharge of trichocysts. We showed that (a) external Ca2+, at least at 3 X 10(-7) M, is necessary for AED to induce exocytosis; (b) a dramatic and transient influx of Ca2+ as measured from 45Ca uptake is induced by AED; (c) this influx is independent of the well-characterized voltage-operated Ca2+ channels of the ciliary membranes since it persists in a mutant devoid of these channels; and (d) this influx is specifically abolished in one of the mutants unable to undergo exocytosis, nd12. We propose that the Ca2+ influx induced by AED reflects an increase in membrane permeability through the opening of novel Ca2+ channel or the activation of other Ca2+ transport mechanism in the plasma membrane. The resulting rise in cytosolic Ca2+ concentration would in turn induce membrane fusion. The mutation nd12 would affect a gene product involved in the control of plasma membrane permeability to Ca2+, specifically related to membrane fusion.

Animals↗
PubMed1990

Prophylactic and therapeutic effects of a monoclonal antibody to tumor necrosis factor-alpha in experimental gram-negative shock.

A monoclonal antibody to recombinant murine tumor necrosis factor-alpha (TNF alpha), TN3-19.12, was used to explore pathogenetic mechanisms and therapeutic strategies in gram-negative shock. In mice receiving an LD90 dose of Escherichia coli O111, TN3-19.12 prevented death if given 1.5 h before or 30 min after challenge. Less protection was conferred if the antibody was given 2.5 h after challenge. In control mice receiving an irrelevant antibody, L2-3D9, TNF alpha levels rose (less than or equal to 185.1 +/- 26.1 ng/ml) by 90 min and had returned to baseline by 5 h. Mice receiving TN3-19.12 did not have this response. TN3-19.12 was of limited benefit in mice receiving Pseudomonas aeruginosa but had no protective effect in cyclophosphamide-treated mice receiving Klebsiella pneumoniae. In L2-3D9-treated mice, TNF alpha levels were elevated to 61.8 +/- 27.9 and 49.7 +/- 5.1 ng/ml by 90 min in the two models, respectively. TNF alpha levels in TN3-19.12-treated mice in these two models were very low (3.9-5.5 ng/ml). TNF alpha is a mediator in gram-negative shock; antibody to TNF alpha can be of value in prophylaxis and treatment, but its clinical use remains to be established.

Animals↗
PubMed1990

Monoclonal antibody to endotoxin core protects mice from Escherichia coli sepsis by a mechanism independent of tumor necrosis factor and interleukin-6.

To study the role of cytokines as mediators of endotoxin-induced shock, the serum levels of tumor necrosis factor (TNF) and interleukin-6 (IL-6) were compared in mice receiving either a monoclonal antibody to endotoxin core (clone 20), an irrelevant monoclonal antibody (A1), or culture media (DMEM/FCS) alone before lethal challenge with live Escherichia coli O111:B4. Clone 20 given 1.5 h before the bacterial challenge protected mice from death (mortality at 48 h 3% vs. 87%, P less than .001). The pattern of IL-6 release was indistinguishable in clone 20 recipients and controls: The area under the curve (AUC) for 5 h was 1.22 +/- 0.07 x 10(6), 1.03 +/- 0.17 x 10(6), and 1.22 +/- 0.07 x 10(6) units/ml for clone 20, A1, and DMEM/FCS, respectively. Similarly, the timing and extent of TNF release in the serum was virtually identical in clone 20 recipients that survived and control animals that died. AUC for 5 h was 30.8 +/- 4.0 x 10(3), 28.1 +/- 1.1 x 10(3), and 30.4 +/- 4.7 x 10(3) ng/ml in clone 20, A1, and DMEM/FCS recipients, respectively. Thus, TNF and IL-6 appear insufficient to cause death in this model of experimental gram-negative shock.

Animals↗
PubMed1990

Laboratory techniques for handling gametes and embryos.

This review describes some basic and novel principles pertaining to the science of in vitro fertilization and embryo culture. Several systems for cell-free culture of gametes and embryos are described. The advantages of a coculture or helper cell system was investigated in several clinical trials using bovine cells from the reproductive tract. Improved embryonic morphology and implantation indicate that standard IVF culture provides suboptimal conditions. Microsurgical methods for assisting in vitro fertilization in cases of severe male factor infertility are also discussed. Thus far, it has been demonstrated that mechanical opening of the zona pellucida by methods such as partial zona dissection enhances fertilization. In addition, the introduction of a limited gap in the zona seems to facilitate hatching of the blastocyst, which may benefit all patients undergoing in vitro fertilization.

Cell-Free System↗
PubMed1990

Observations on the morphology of pronuclei and nucleoli in human zygotes and implications for cryopreservation.

The effects of cryopreservation on human zygotes at various stages between the appearance of pronuclei and their close association were investigated. Pronuclear zygotes (n = 233) from 101 patients were frozen using propanediol 21-35 h following egg collection. The incidence of implantation of thawed pronuclear zygotes frozen 29-35 h following oocyte collection was significantly higher than that of younger pronuclear zygotes (28 versus 10%, respectively). Zygote age did not affect cell survival following cryostorage. The diameter and association of pronuclei and the number and distribution of nucleoli were determined from video tape recordings of 140 fresh zygotes. Pronuclear migration continued after pronuclear enlargement. The number of nucleoli remained constant during pronuclear migration, but their random distribution within the pronucleus diminished. Strongly adhered pronuclei had significantly more aligned nucleoli on adjacent sides than pronuclei which were still visually separated by ooplasm. This equatorial distribution of nucleoli was noted in the majority of zygotes older than 26 h. The findings suggest that zygote cryopreservation should be initiated when pronuclear migration is completed. This moment can be determined accurately by studying pronuclear association and nucleolar alignment.

Cell Nucleolus↗
PubMed1990

Restriction fragment length polymorphisms in isolates of Aspergillus fumigatus probed with part of the intergenic spacer region from the ribosomal RNA gene complex of Aspergillus nidulans.

Differences in restriction fragment length polymorphisms (RFLPs) have been detected in isolates of Aspergillus fumigatus. Genomic DNA from 11 isolates was digested with EcoRI, separated by electrophoresis, Southern blotted and probed with DNA from the intergenic spacer or non-transcribed spacer region of the rRNA gene complex of Aspergillus nidulans. Three distinct RFLP patterns were detected which differed from the control patterns observed with A. nidulans, Aspergillus flavus and Aspergillus niger hybridized with the same probe. Furthermore, the differences in RFLP patterns in the A. fumigatus isolates were not detected when probed with DNA coding for the rRNA complex in Saccharomyces cerevisiae. These findings may be of use in the study of the epidemiology and pathogenesis of infections caused by A. fumigatus.

Aspergillus fumigatus↗
PubMed1990

Pro-inflammatory mediators induce sustained release of prostaglandin E2 from human dermal microvascular endothelial cells.

The vasodilator prostaglandin E2 has been proposed as a mediator of erythema in a variety of cutaneous inflammatory reactions and prostacyclin levels have been found to be elevated in ultraviolet induced erythema. Human recombinant interleukin 1 alpha and lipopolysaccharide induced a concentration- and time-dependent release of prostaglandin E2, but not prostacyclin, from cultured neonatal and adult human dermal microvascular endothelial cells. Prostaglandin E2 was measurable at 2 h after stimulation with 1 U/ml interleukin 1 alpha, levels increased rapidly up to 6 h and more slowly up to 24 h. Lipopolysaccharide (20 micrograms/ml) induced measurable release of prostaglandin E2 between 2 and 4 h after stimulation and release continued up to 24 h when incubation was terminated. With both agonists, release of prostaglandin E2 was inhibited by indomethacin and significantly reduced by cycloheximide. The sensitivity and magnitude of responses of the cutaneous endothelial cells to these pro-inflammatory stimuli appeared to be dependent on their derivation.

Adult↗
PubMed1990

Sequential measurement of the murine acute-phase protein serum amyloid P component (SAP) as an indicator of graft-versus-host disease following allogeneic bone marrow transplantation in mice.

Murine models of bone marrow transplantation (BMT) are used commonly for studies of the pathogenesis and treatment of graft-versus-host disease (GVHD). We report here that the sequential measurement of the mouse acute-phase protein SAP can be used to provide a sensitive, quantitative index of the severity of GVHD. Thirty mice underwent allogeneic, and a further 30 syngeneic BMT. GVHD was assessed in vivo by clinical appearances and weight change, and post mortem by histology and calculation of splenic indices. Blood was obtained twice/week for SAP measurement and blood culture. In all mice an initial rise in SAP levels due to irradiation was followed by a return to baseline. Thereafter in syngeneic marrow recipients levels remained low. In contrast, after allogeneic BMT SAP levels rose progressively as mice developed GVHD, reaching a peak of 135 micrograms/ml prior to death, from a nadir at day 20 of 15 micrograms/ml. Mice with high splenic indices and histological evidence of severe GVHD had significantly higher SAP levels than mice with mild GVHD (P = 0.0002). Elevation in SAP levels occurred independently of bacteraemia. We conclude that in murine BMT sequential measurement of SAP provides an objective means of assessing GVHD in vivo.

Animals↗
PubMed1990

How willing are general practitioners to manage narcotic misuse?

In 1989 a self-administered questionnaire concerning current management of, attitudes to, and knowledge of, narcotic misuse was completed by 206 Inner London general practitioners. Results showed that whilst over three quarters were prepared to offer patients supportive interviews, few were willing to prescribe for them, most preferring to refer to specialist facilities. Only 33 respondents had received adequate training in the management of narcotic misuse, but over a quarter expressed an interest in small group training to improve their skills. These findings are discussed in relation to Department of Health guidelines concerning the management of narcotic misuse.

Adult↗
PubMed1990

Changes in a light-cured composite resin material used to restore primary anterior teeth: an eighteen month in vivo study.

A simple method for treating grossly decayed primary anterior teeth (GDPAT) is of clinical importance since the age of the patient precludes lengthy and difficult procedures. This study assessed the suitability of a light-cured microfilled composite resin material for the repair of GDPAT. The material Durafill was used to restore 81 primary teeth in 24 children (mean age 3.5 y). The restorations were assessed according to predetermined criteria at 6, 12, and 18 months. Results showed a significant deterioration in cavomarginal discoloration and anatomic form (p less than 0.05). Changes in anatomic form were significantly related to marginal adaptation, secondary caries, gingivitis and pain (p less than 0.05). Despite the observed changes, Durafill performed adequately and offers the dentist a simple method for restoring GDPAT.

Child↗