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N Cohen

Publications and source records attributed to N Cohen.

448 records · Page 25Linked to original sources
PubMedDate not supplied

Ontogeny of CTX expression in xenopus.

In Xenopus, the type I transmembrane protein, CTX (cortical thymocyte-specific antigen of Xenopus), is hypothesized to play a role in thymocyte differentiation and/or thymic selection. The present studies were undertaken to gather additional evidence in support of a postulated association of CTX with a differentiation step of a cell population that corresponds to the murine immature double positive (CD4+CD8+TCR+) thymocyte subset. During ontogeny, cell surface expression of CTX on thymocytes can first be detected by immunocytochemistry and flow cytometry at 8 days post-fertilization, about 1 day after CD8+ cells first appear. By 12 days post-fertilization, T-cells in the entire cortex except for the outer most layer of cells, are intensely CTX positive, whereas those in the medulla are negative. This pattern persists throughout larval and postmetamorphic life.

Animals↗
PubMedDate not supplied

A high incidence antibody (anti-Sc3) in the serum of a Sc:-1,-2 patient.

An individual has been found whose red blood cells type as Sc:-1,-2, and do not absorb or yield on elution, anti-Sc1 or anti-Sc2. The patient produced an antibody reacting with all red blood cells, except those that were Sc:-1,-2. The antibody, here called anti-Sc3, was shown not to contain separable specificities when absorption studies were performed with Sc:-1,2 and Sc:1,-2 red blood cells. It appears that all Sc:1 or Sc:2 red blood cells are also Sc:3, while those that are Sc:-1,-2 are Sc:-3. A family study did not reveal the genetic background responsible for this Sc:-1,-2 phenotype.

Aged↗
PubMedDate not supplied

Effect of ethanol on the retention of americium-241 in the baboon liver.

The oral administration of ethyl alcohol enhanced the excretion of 241Am from the liver of a baboon by 2.5 times that of a control animal. After ethanol administration, increases in the total content of 241Am excreted in feces were accompanied by corresponding increases in fecal volumes, although administration of nonalcoholic cathartics would not be expected to produce a similar effect. The effectiveness of ethanol as a decorporating agent may result from its ability to mobilize intracellularly bound 241Am from the liver, thereby making the nuclide more available for metabolic secretory mechanisms occurring via liver-bile-fecal route.

Americium↗
PubMedDate not supplied

Responses of neurologic complications of AIDS to 3'-azido-3'-deoxythymidine and 9-(1,3-dihydroxy-2-propoxymethyl) guanine. I. Clinical features.

Fourteen patients with AIDS were treated for 23 neurologic complications: four episodes of acute meningoencephalitis; eight episodes of subacute encephalopathy; two cases of progressive multifocal leukoencephalopathy; and nine cases of polyneuropathy. Nine patients were treated with 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG), one with 3'-azido-3'-deoxythymidine (AZT), and four initially with DHPG directed against cytomegalovirus (CMV) retinitis or encephalitis and subsequently with AZT against human immunodeficiency virus (HIV) encephalopathy. CMV retinitis was a helpful clinical observation indicating neurologic involvement. DHPG produced improvement in two of three cases of acute meningoencephalitis but was ineffective in cases of subacute encephalopathy or neuropathy. AZT therapy resulted in resolution in both of the two treated cases of acute confusional state and in two of the four treated cases of polyradiculoneuropathy with paraparesis but was ineffective in the late stage of subacute encephalopathy. These results suggest that CMV is important in some cases of acute meningoencephalitis, whereas HIV is a dominant pathogen in subacute dementia and polyneuropathy in patients with AIDS. DHPG may be beneficial in the former, whereas AZT appears to be effective in the latter complications.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Behaviorally conditioned immunosuppression.

An illness-induced taste aversion was conditioned in rats by pairing saccharin with cyclophosphamide, an immunosuppressive agent. Three days after conditioning, all animals were injected with sheep erythrocytes. Hemagglutinating antibody titers measured 6 days after antigen administration were high in placebo-treated rats. High titers were also observed in nonconditioned animals and in conditioned animals that were nor subsequently exposed to saccharin. No agglutinating antibody was detected in conditioned animals treated with cyclophosphamide at the time of antigen administration. Conditioned animals exposed to saccharin at the time of or following the injection of antigen were significantly immunosuppressed. An illness-induced taste aversion was also conditioned using LiCl, a nonimmunosuppressive agent. In this instance, however, there was no attenuation of hemagglutinating antibody titers in response to injection with antigen.

Animals↗
PubMedDate not supplied

Alternate sites of lymphopoiesis in the amphibian embryo.

The presumptive ventral blood islands were reciprocally transplanted between chromosomally labelled 72-hour-old leopard frog embryos. At 10 days of development, the differentiating epithelial thymus glands were surgically removed. Following metamorphosis, the spleen and bone marrow from juvenile frogs were analysed cytophotometrically. During normal ontogeny, the vast majority of peripheral lymphocytes are derived from the thymus, not the ventral blood islands. In the absence of the thymus, the ventral blood islands made the major lymphocyte contribution to the peripheral lymphoid organs. Thus, removal of the thymus appears to initiate an alternate pathway of lymphocyte differentiation in the leopard frog.

Animals↗
PubMedDate not supplied

Adjuvant effects of freely ingested cholera toxin on systemic antibody and DTH responses to protein antigen.

Recent evidence suggests that immunological handling of antigen in the gut may be different when animals voluntarily ingest antigen in their drinking fluid. Therefore, we investigated whether the adjuvant effects of CT were evident in mice that voluntarily ingested CT together with keyhole limpet hemocyanin (KLH) in 1.0 ml chocolate milk. Initially, it was found that ingestion of 2 mg KLH for up to four times (one ingestion per week) did not induce serum IgG anti-KLH antibody; however, KLH-specific IgG was detected if KLH was ingested together with 10 micrograms CT. Furthermore, 50 days after only one ingestion of CT+KLH, the serum IgG response to intraperitoneal challenge with 100 micrograms KLH was significantly elevated with respect to the response of mice who previously had ingested either KLH alone, CT alone, or drinking fluid only. This observation was repeated in further experiments showing an enhanced IgG response to 100 micrograms KLH ip given 7 or 14 days after a single ingestion of 2 or 5 mg KLH mixed with different doses (0.5-20 micrograms) CT. The lowest effective CT dose for serum IgG anti-KLH adjuvanticity was found to be 1 microgram; the highest effective dose was 10 micrograms, there being no additive effect with 20 micrograms CT. It was also found that simultaneous ingestion of KLH (2 or 5 mg) with CT (0.5-20 micrograms) followed 7 or 14 days later by 100 micrograms KLH ip, increased the 24 hr footpad DTH response to 50 micrograms KLH administered 43 days after the ip challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMedDate not supplied

Air-CT cisternography and canalography for small acoustic neuromas.

Disenchantment with the limitations, and in some cases the morbidity, of currently used radiologic techniques for the demonstration or exclusion of small acoustic neuromas prompted development of an examination using small amounts of intrathecal air and computed tomography (CT). A prospective study was designed to evaluate air CT cisternography/canalography, wherein patients with the clinical symptoms of acoustic neuroma but with negative enhanced CT, were evaluated by metrizamide CT cisternography followed by air CT cisternography/canalography. Pantopaque cisternography was then performed as a control procedure. Four patients had surgically proven tumors. In 13 others, accumulated evidence indicated no tumors were present. Results suggest that air-CT cisternography is superior to all other diagnostic methods in defining small acoustic neuromas, and may exclude an intracanalicular lesion without the potential hazards of Pantopaque cisternography or high concentration metrizamide tomocisternography. With air-CT cisternography, there were no errors in this series.

Air↗
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Relationship between renal mass and atrial natriuretic peptide release. 1. Paradoxical effect of unilateral nephrectomy on serum atrial natriuretic peptide in rats.

Serial serum atrial natriuretic peptide (ANP) determinations were performed in 15 uninephrectomized Charles River rats and in 15 sham-operated control animals during the 60 days following surgery. In a second group of 7 control and 7 uninephrectomized animals, housed in metabolism cages, serum ANP, body weight, 24-hour urine volume, osmolality and sodium excretion were serially measured. In a third group of uninephrectomized and control rats the effect of acute salt loading 24 h, 6 and 60 days after surgery on serum ANP was studied. No significant changes in ANP levels were observed during the 60 days following surgery in control animals. In the uninephrectomized animals a sharp drop in basal ANP levels was evident 24 and 48 h after surgery, but increased levels of serum ANP were seen from day 6 to 28. Thereafter ANP returned to baseline levels for the rest of the study period. Urinary sodium excretion decreased in the nephrectomized animals on days 1 and 2 following surgery. No such change was seen in the control animals during the same period. Body weight, 24-hour urine volume and urine osmolality were not statistically different in the nephrectomized vs. control rats at any time and remained constant in each group throughout the experimental period. Central venous pressure (CVP) did not change significantly in both groups 24 h and 6 days following surgery. CVP rose similarly in both groups immediately following saline loading and returned to preload levels 1 h later.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
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Relationship between renal mass and atrial natriuretic peptide release. 2. Acute effects of various degrees of renal damage on atrial natriuretic peptide release in rats.

We studied basal serum atrial natriuretic peptide (ANP) levels and the response to acute salt loading in rats with different grades of functional renal mass reduction. The six groups of rats studied included 2 controls, i.e. unoperated (n = 12) and sham-operated (n = 24) groups. Each of the 4 experimental groups (n = 24 in each) underwent one of the following procedures: bilateral nephrectomy; unilateral nephrectomy; bilateral ureteral ligation; unilateral ureteral ligation. Basal ANP was assessed in the intact controls and operated groups 4, 8, 16 and 24 h after surgery. In addition, ANP was determined in the sham-operated controls and in the experimental groups 1 h following acute intravenous saline loading performed 4 h after surgery with central venous pressure monitoring. Basal ANP dropped significantly following bilateral nephrectomy but was not significantly altered after unilateral nephrectomy or the two modalities of ureteral ligation. In all 4 experimental groups ANP failed to rise after saline loading. We conclude that substantial renal damage results in early impairment in ANP secretion suggesting the existence of a renal physiological stimulus controlling ANP release by cardiac atria.

Animals↗
PubMedDate not supplied

Nephrectomy enhances interleukin 6 secretion by interleukin 1-stimulated mesangial cells in vitro.

BACKGROUND: Kidney mesangial cells are capable of producing and responding to interleukin 6 (IL-6) . In experimental glomerulonephritis mesangial cell proliferation correlates with increased IL-6 production. To investigate the involvement of IL-6 in post-nephrectomy compensatory hypertrophy, we studied the capacity of mesangial cells from single remaining kidneys to secrete IL-6 in culture. METHODS: Mesangial cells were obtained from uni-nephrectomized or sham-nephrectomized Charles River rats. Cell cultures were maintained for 8 days in DMEM/FI2HAM medium supplemented with IL-1 of interferon (IFN). IL6 production was measured using an IL-6-dependent B9 human hybridoma cell line. RESULTS: IL-6 production by mesangial cells from normal kidneys was significantly enhanced by IL-1, compared to unstimulated cells (p<0.01), and the increase was significantly greater in mesangial cells from a single remaining kidney (p<0.01). All cultures grown in control medium or with addition of IFN produced similar amounts of IL-6. CONCLUSION: Mesangial cells from single remaining kidneys in culture maintain an exaggerated capacity to produce IL-6 in response to IL-1. IL-6 was reported to enhance or inhibit mesangial cell proliferation in vitro. We suggest that the local over production of IL-6 by a single remaining kidney may play a role in regulating a sequence of physiological events in compensatory renal growth, initially stimulating mesangial cell proliferation and later blunting the process.

Animals↗