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Biomedical subjects

J Cohen

Publications and source records attributed to J Cohen.

At least 991 records · Page 55Linked to original sources
PubMed1991

Responses of human dermal microvascular endothelial cells to histamine and their modulation by interleukin 1 and substance P.

The action of histamine on human dermal microvascular endothelial cells and modulation of its effects by the cytokine interleukin-1 and the vasoactive neuropeptide substance P have been investigated. Histamine (10(-6)-10(-3) M) induces release of prostaglandin E2 in a concentration- and time-dependent manner. Prostaglandin E2 release is facilitated principally by histamine H1 receptors as the H1 receptor antagonist pyrilamine attenuates prostaglandin E2 release whereas the H2 receptor antagonist cimetidine only slightly reduces release. In contrast to other cells, the histamine/receptor interaction is not associated with increased intracellular accumulation of the cyclic nucleotides, cyclic AMP, or cyclic GMP. Interleukin-1 induces a concentration-dependent release of prostaglandin E2 following 24 h incubation. However, substance P does not increase release of prostaglandin E2 above baseline. In cells incubated with 1 U/ml human recombinant interleukin 1 alpha for 24 h prior to stimulation with histamine (10(-5)-10(-3) M) for 30 min, there is a significant potentiation of histamine-induced release of prostaglandin E2 (p less than 0.05). Using a solubilized cell sonicate prepared from human dermal microvascular endothelial cells incubated with 1 U/ml human recombinant interleukin 1 alpha for 24 h, conversion of exogenous arachidonic acid into prostaglandin E2 increased by 60.19 +/- 18.28%. Cycloheximide partially reduces the increased conversion but completely blocks interleukin-1-induced release of prostaglandin E2 from intact cells. Substance P does not potentiate histamine-induced release of prostaglandin E2 or increase arachidonic acid conversion. These results demonstrate that human dermal microvascular endothelial cells are responsive to histamine and that interleukin-1, but not substance P, can potentiate histamine-induced release of prostaglandin E2. Interleukin-1 appears to act, at least in part, by regulating the availability of free arachidonic acid. Interactions between histamine and interleukin-1 may be important in the modulation of inflammatory reactions in skin.

Dinoprostone↗
PubMed1991

Detection of group B and C rotaviruses by polymerase chain reaction.

We adapted the polymerase chain reaction (PCR) to detect the noncultivatable group B and C rotaviruses and introduced a simple and convenient technique to purify viral RNA from stool specimens. Double-stranded RNA present in stool extracts was purified by adsorption to hydroxyapatite and was used as the template for reverse transcription and polymerase amplification. Primer pairs specific for group B (gene 8) and group C (gene 6) rotaviruses were selected to amplify group-characteristic sizes of cDNA copies readily identifiable in ethidium bromide-stained agarose gels. These primer pairs were used separately in individual PCR assays or were pooled with a primer pair specific for group A rotavirus (gene 9) in a combined PCR assay for the simultaneous detection of all three rotavirus groups. The method was very sensitive and was used to identify both human and porcine strains of group B and C rotaviruses in stool specimens. A second PCR amplification with internal group-specific primers served to increase further the sensitivity of the test and to confirm the diagnostic results obtained in the first amplification.

Base Sequence↗
PubMed1991

Immunization with baculovirus-expressed recombinant rotavirus proteins VP1, VP4, VP6, and VP7 induces CD8+ T lymphocytes that mediate clearance of chronic rotavirus infection in SCID mice.

Clearance of chronic murine rotavirus infection in SCID mice can be demonstrated by adoptive transfer of immune CD8+ T lymphocytes from histocompatible donor mice immunized with a murine homotypic rotavirus (T. Dharakul, L. Rott, and H.B. Greenberg, J. Virol 64:4375-4382, 1990). The present study focuses on the protein specificity and heterotypic nature of cell-mediated clearance of chronic murine rotavirus infection in SCID mice. Heterotypic cell-mediated clearance was demonstrated in SCID mice infected with EDIM (murine) rotavirus after adoptive transfer of CD8+ T lymphocytes from BALB/c mice that were immunized with a variety of heterologous (nonmurine) rotaviruses including Wa (human, serotype 1), SA11 and RRV (simian, serotype 3), and NCDV and RF (bovine, serotype 6). This finding indicates the serotypic independence of T-cell-mediated rotavirus clearance. To further identify the rotavirus proteins that are capable of generating CD8+ T cells that mediate virus clearance, donor mice were immunized with SF-9 cells infected with a baculovirus recombinant expressing one of the following rotavirus proteins: VP1, VP2, NS53 (from RF), VP4, VP7, NS35 (from RRV), VP6, and NS28 (from SA11). SCID mice stopped shedding rotavirus after receiving CD8+ T cells from mice immunized with VP1, VP4, VP6, and VP7 but not with VP2, NS53, NS35, NS28, or wild-type baculovirus. These results suggest that heterotypic cell-mediated clearance of rotavirus in SCID mice is mediated by three of the major rotavirus structural proteins and by a putative polymerase protein.

Animals↗
PubMed1991

Expression of rotavirus VP2 produces empty corelike particles.

The complete VP2 gene of bovine rotavirus strain RF has been inserted into the baculovirus transfer vector pVL941 under the control of the polyhedrin promoter. Cotransfection of Spodoptera frugiperda 9 cells with wild-type baculovirus DNA and transfer vector DNA led to the formation of recombinant baculoviruses which contain bovine rotavirus gene 2. Infection of S. frugiperda cells with this recombinant virus resulted in the production of a protein similar in size and antigenic properties to the authentic rotavirus VP2. The protein binds double-stranded RNA and DNA in an overlay protein blot assay. Expressed VP2 assembles in the cytoplasm of infected cells in corelike particles 45 nm in diameter. These corelike particles were purified by sucrose gradient centrifugation and found to be devoid of nucleic acid. Coexpression of VP2 and VP6 from heterologous rotavirus strains (bovine and simian) resulted in the formation of single-shelled particles. These results definitively show the existence of an innermost protein shell in rotavirus which is formed independently of other rotavirus proteins. These results have implications for schemes of rotavirus morphogenesis.

Animals↗
PubMed1991

Differential effects of laminin and merosin on neurite outgrowth by developing retinal ganglion cells.

In previous work, we showed that cultured avian embryonic retinal ganglion cells (RGC) extend neurites on EHS-laminin early in development, but lose this ability with maturation, as a result of a sharp decline in laminin receptor numbers. Here we show that EHS-laminin promotes neurite outgrowth also from embryonic mammalian RGC, in contrast to previous reports, and that these exhibit similar age-dependent growth responses on laminin. Antibody blocking studies show that this behaviour is mediated in mouse RGC by alpha 6 beta 1 integrin dimers. The laminin isoform merosin is also effective as a neurite outgrowth-promoting substrate for RGC but differs in its ability to elicit a response at advanced stages of development (up to hatching in the chick). Neurite outgrowth by RGC on merosin is inhibited, at all ages, by the function-blocking, anti-beta 1 integrin antibody, CSAT, suggesting that these neurons use alternative alpha beta 1 dimers in their interactions with EHS-laminin and merosin. Together, these findings emphasise the generality of the responsiveness of vertebrate embryonic RGC to laminin during development, and reveal interesting differences in the effects of laminin variants on CNS axon growth and regeneration.

Animals↗
PubMed1991

Polioencephalitis, stress, and the etiology of post-polio sequelae.

Post-mortem neurohistopathologies that document polio virus-induced lesions in reticular formation and hypothalamic, thalamic, peptidergic, and monoaminergic neurons in the brain are reviewed from 158 individuals who contracted polio before 1950. This polioencephalitis was found to occur in every case of poliomyelitis, even those without evidence of damage to spinal motor neurons. These findings, in combination with data from the 1990 National Post-Polio Survey and new magnetic resonance imaging studies documenting post-encephalitis-like lesions in the brains of polio survivors, are used to present two hypotheses: 1) polioencephalitic damage to aging reticular activating system and monoaminergic neurons is responsible for post-polio fatigue, and 2) polioencephalitic damage to enkephalin-producing neurons is responsible for hypersensitivity to pain in polio survivors. In addition, the antimetabolic action of glucocorticoids on polio-damaged, metabolically vulnerable neurons may be responsible for the fatigue and muscle weakness reported by polio survivors during emotional stress.

Brain↗
PubMed1991

Incomplete nondisplaced tibial osteotomy for treatment of osteoarthritic knee pain.

Intraosseous venous hypertension is considered a significant factor in the production of knee pain secondary to degenerative arthrosis, thus vascular decompression by means of tibial osteotomy is a rational option for treatment of selected patients. A preliminary report is presented of six patients with symptoms of primary or secondary degenerative arthrosis who were treated by incomplete nondisplaced proximal tibial osteotomy with good or excellent results. These patients were refractory to nonoperative treatment and were not deemed suitable candidates for angulated osteotomy, arthroscopic surgery alone, or total knee arthroplasty. Patients ranged in age from 36 to 61 years (mean age: 47 years). Follow-up ranged from .8 to 6.7 years (mean: 3.1 years). The subjects were studied postoperatively by interview, physical examination, radiographs, and bone scans. Results were assessed using the knee rating system of The Hospital for Special Surgery.

Adult↗
PubMed1991

Klippel-Feil syndrome. An unusual association with Sprengel deformity, omovertebral bone, and other skeletal, hematologic, and respiratory disorders. A case report.

An unusual presentation of Klippel-Feil syndrome prompts a detailed description of this anomaly and a review of the literature. The patient, a six-year-old boy, had, in addition, multiple associated congenital anomalies that included Sprengel deformity, omovertebral bone, scoliosis, hypoplasia of the right thumb, plagiocephaly, choanal atresia, and Diamond-Blackfan anemia.

Abnormalities, Multiple↗
PubMed1991

Ganciclovir treatment for cytomegalovirus infection in immunocompromised patients with renal disease.

The safety and efficacy of a 10-day course of ganciclovir therapy was assessed in 17 consecutive patients with proven cytomegalovirus infection. The patients were receiving immunosuppressive therapy for a variety of non-malignant renal conditions, including renal transplantation (seven patients), small vessel vasculitis (six patients), systemic lupus erythematosus (three patients) and Goodpasture's disease (one patient). Fifteen patients were pyrexial at the time of their cytomegalovirus infection. Twelve patients had pneumonitis manifesting as a pulmonary parenchymal infiltrate or a reduction in gas transfer. Fourteen patients had a significant lymphopenia (lymphocyte count less than 1 x 10(9)/l), nine were leucopenic (white cell count less than 3.5 x 10(9)/l) and nine had abnormal liver biochemistry. One patient had an infection of the ileum and one an infection of the larynx. All these disease manifestations responded completely to a single course of ganciclovir therapy. There were no clinical relapses and no side effects were observed. Ganciclovir is a safe and effective therapy when administered early in the course of cytomegalovirus infection in immunosuppressed patients with renal impairment.

Adolescent↗
PubMed1991

Primary care in New York State: report and recommendations of the associated medical schools of New York.

Medical education in New York is unique in the country in its scope and its diversity. It is important, as we go forward, that these strengths be neither eroded nor compromised. The AMS member institutions are making a collective commitment to work together to promote changes that will improve medical education for all students by providing them with enriched experience in primary care. Our major resource is faculty. To whatever degree medical schools can influence career choice, it is essential to this aim that the best possible people are placed in the settings in which primary care is taught. The schools will intensify their efforts to recruit and retain such faculty and, in whatever way is appropriate to each institution, provide them with the stature needed to emphasize the value which the school places on primary care. The schools will also work to provide exposure to primary care early in a student's academic career given anecdotal evidence, at least, that such early experience can influence subsequent specialty choice. Finally, the medical schools will assume greater responsibility for graduate medical education. If, with state support, ambulatory teaching sites are developed, the schools will make every effort to assure that they are staffed with high-quality faculty. Residents and students must see primary care practiced with total commitment to quality. It is hoped that, with state-initiated improvements in the practice environment, the ultimate outcome will be an increase in the number of our graduates selecting primary care disciplines for their practices and locating in areas in need of physicians.2+ Corporation, and the Greater New York Hospital Association. We are ready to work with others toward our common objectives, and we call on all of those who share these concerns to participate with us.

Career Choice↗
PubMed1991

Administration of clonazepam in the treatment of TMD and associated myofascial pain: a double-blind pilot study.

A double-blind pilot study was undertaken to test the administration of low doses of the long-acting benzodiazepine drug clonazepam in the management of chronic intractable temporomandibular disorder/myofascial pain patients who were not responsive to occlusal splint, behavioral, and physical therapy. Clonazepam was selected for its long duration and its cholinergic/GABA-ergic/serotonergic, anxiolytic, muscle relaxant, and sedative properties. Clonazepam appears to be effective when compared to a placebo. However, caution must be observed with long-term administration of clonazepam because of potential side effects such as depression and liver dysfunction. Indiscriminate administration of clonazepam may be harmful to the patient.

Adolescent↗
PubMed1991

Bond strength of glass ionomer cement to composite resin.

This report assesses the effect of acid etching, acid etching plus bonding adhesive and bonding adhesive only, on the bond strength of one light curing and two chemical curing glass ionomer cements (GICs) to composite resin. Bonded specimens were fractured using a three point flexural jig. The only bond obtained with the chemically curing cements was after acid etching and bonding adhesive application. The light curing cements produced a bond with all treatments but a true cohesive fracture was only obtained after application of the dentine primer and bonding adhesive of the particular bonding system employed. It is recommended that a bonding adhesive be applied after acid etching chemically curing GICs in order to achieve a bond to composite resin. The light curing GIC should not be etched with phosphoric acid and is the material of choice as it is both stronger and less technique sensitive than the chemically curing GICs. Manufacturers' instructions may not always give the best results.

Analysis of Variance↗
PubMed1991

Effect of impression technique and multiple pours on accuracy of stone models.

The number of accurate repour models obtainable from a single impression is of clinical importance. This study was designed to compare the accuracy of initial and repour models obtained from an impression recorded in a hydrophilic addition curing silicone and to determine whether or not this accuracy is affected by the impression technique employed and whether any interaction between impression techniques and levels of pour existed. The laminated and putty wash plus spacer techniques were employed. Six impressions were recorded of a brass master model with each technique. Improved stone models were poured after 2 hours and then repoured in the same impression at 3, 4, 5 and 6 hours. Thus, 30 models were poured with each impression technique. Using a reflex microscope, measurements between two fixed points on the brass model were taken and compared with similar measurements obtained from the stone models. The analysis of variance indicates that no significant difference exists between impression techniques (p greater than 0.05) and between the first pour and first repour model (p greater than 0.05). With the material tested, this study indicates that the laminated and putty wash plus spacer techniques both give accurate impressions and that only two accurate models can be poured.

Analysis of Variance↗