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Biomedical subjects

J K Nicholson

Publications and source records attributed to J K Nicholson.

At least 253 records · Page 14Linked to original sources
PubMed1986

In vitro infection of human monocytes with human T lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV).

We explored the possibility that normal human monocytes can be infected with the retrovirus human T lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV). The T4 antigen, believed to be the receptor for HTLV-III/LAV binding to CD4 cells, is found on monocytes at low levels. Anti-T4A, which recognizes an epitope on the T4 molecule, inhibits viral binding to monocytes, and virus inhibits anti-T4A binding, although inhibition in both cases is not total. Virus particles were detected in HTLV-III/LAV-pulsed monocytes by electron microscopy as early as 10 min and for up to 3 days after inoculation, although budding virus was not observed. Monocytes were exposed to virus, were washed, and were cultured. Monocyte cultures were monitored by conventional assays for virus replication: immunofluorescence detection of cytoplasmic virus, supernatant reverse transcriptase activity, and supernatant virus antigen. These assays were either negative or at the lower limits of positivity. However, the amount of infectious virus was shown to increase over time in monocyte cultures by harvesting monocytes or their culture supernatants and titrating them into assay cultures containing stimulated T cells. Virus recovery from monocytes and virus recovery from T cells differed both quantitatively and qualitatively. Recovery from T cells and T cell supernatants peaked at 3 to 6 days and declined thereafter. Recovery from monocytes and monocyte supernatants increased over time in culture and never attained the levels of T cell cultures. Taken together, these studies indicate that HTLV-III/LAV binds to monocytes via the T4 molecule and enters the cells. Infectious virus is retained and increases with time in infected monocyte cultures. Both viral binding and infection are at low levels compared with levels in T cells. Unlike the usual infection of T cells characterized by high level virus replication with cell depletion, the infection appears to be persistent in monocytes.

Antibodies, Monoclonal↗
PubMed1986

Binding of HTLV-III/LAV to T4+ T cells by a complex of the 110K viral protein and the T4 molecule.

Human T-lymphotropic virus type III (HTLV-III) or lymphadenopathy-associated virus (LAV) is tropic for human T cells with the helper-inducer phenotype, as defined by reactivity with monoclonal antibodies specific for the T4 molecule. Treatment of T4+ T cells with monoclonal antibodies to T4 antigen blocks HTLV-III/LAV binding, syncytia formation, and infectivity. Thus, it has been inferred that the T4 molecule itself is a virus receptor. In the present studies, the surfaces of T4+ T cells were labeled radioactively, and then the cells were exposed to virus. After the cells were lysed, HTLV-III/LAV antibodies were found to precipitate a surface protein with a molecular weight of 58,000 (58K). By blocking and absorption experiments, this 58K protein was identified as the T4 molecule. No cell-surface structures other than the T4 molecule were involved in the antibody-antigen complex formation. Two monoclonal antibodies, each reactive with a separate epitope of the T4 molecule, were tested for their binding capacities in the presence of HTLV-III/LAV. When HTLV-III/LAV was bound to T4+ T cells, the virus blocked the binding of one of the monoclonal antibodies, T4A (OKT4A), but not of the other, T4 (OKT4). When HTLV-III/LAV was internally radiolabeled and bound to T4+ T cells which were then lysed, a viral glycoprotein of 110K (gp110) coprecipitated with the T4 molecule. The binding of gp110 to the T4 molecule may thus be a major factor in HTLV-III/LAV tropism and may prove useful in developing therapeutic or preventive measures for the acquired immune deficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Human sympathetic ophthalmia. Immunologic analysis of the vitreous and uvea.

The inflammatory cell reaction within the vitreous and uvea of a human eye with atypical sympathetic ophthalmia was studied immunohistologically and with the fluorescence-activated cell sorter. The uveal infiltrate consisted predominantly of T cells of the helper/inducer subset, with less than 5% of the cells characterized as B cells, plasma cells, or monocytes. These results suggest that T cells perform an important role in atypical human sympathetic ophthalmia. A similar population of mononuclear cells was observed in the vitreous inflammatory infiltrate, in marked contrast to the peripheral blood, where there was a significant depression of circulating T cells. The similarity between the inflammatory cell populations within the vitreous cavity and uvea, in contrast to the peripheral blood, underlines the importance of studying the intraocular inflammatory reaction in uveitis to gain further insight into the mechanism of this disease.

Autoimmune Diseases↗
PubMed1986

1H NMR studies of urine during fasting: excretion of ketone bodies and acetylcarnitine.

High-resolution 1H NMR spectroscopy has been applied to a study of urine from five normal human subjects during a 48-h period of fasting and for 22 h thereafter. The excretion rates of all three ketone bodies (acetoacetate, 3-D-hydroxybutyrate, and acetone), acetylcarnitine, creatinine, and sarcosine during this period were measured. Parallel increases in the excretion of the ketone bodies and acetylcarnitine were observed during fasting with little change in the output of creatinine and sarcosine.

3-Hydroxybutyric Acid↗
PubMed1986

Coordinate and independent effects of heroin, cocaine, and alcohol abuse on T-cell E-rosette formation and antigenic marker expression.

Simultaneous and independent use of cocaine and alcohol by heroin addicts was shown to variably modulate the ability of their T cells to form E-rosettes with sheep erythrocytes (E). As reported previously, the percentages of E-rosette-forming T cells of both active and total types were depressed in association with heroin addiction. We show here that the kinetic curve of the rate of E-rosette formation is also depressed by heroin use and that the use of cocaine but not alcohol by heroin addicts reverses depression of E-rosette formation by heroin. The percentages of E-rosette-forming T cells from the bloods of heroin addicts who used both alcohol and cocaine, as well as the kinetic rate curves of E-rosette formation, were intermediate between the essentially normal levels found for heroin addicts who used cocaine and the severely depressed levels evident for users of heroin alone or heroin plus alcohol. Modulation of the levels of E-rosette formation by alcohol used in conjunction with cocaine and/or heroin was variably dose dependent. Polydrug effects evident by analyses of E-rosette formation were not seen when the percentages of lymphocytes reactive with LYT-3 (anti-E-receptor, 9.6 epitope) and OKT-3 (anti-total T cell) monoclonal antibodies were assessed cytofluorometrically, although the data suggested that subnormal percentages of LYT-3+ T cells were present when heroin addicts also used cocaine. These findings are relevant to basic understanding of T-cell physiology from a neuroimmunological perspective and also suggest ways that addictive drugs may modulate the immunocompetence of drug addicts.

Adult↗
PubMed1986

T-cytotoxic/suppressor cell phenotypes in a group of asymptomatic homosexual men with and without exposure to HTLV-III/LAV.

The number of lymphocytes bearing the Leu 2+ or T8+ (suppressor/cytotoxic) phenotype is elevated in asymptomatic homosexual men. By two-color immunofluorescence using paired monoclonal antibodies (alpha-Leu 2 and alpha-Leu 15, alpha-Leu 2 and alpha-Leu 7, alpha-Leu 7 and alpha-Leu 11), we enumerated phenotypic subpopulations that are associated with cytotoxic, suppressor, or natural killer function. Both cytotoxic (Leu 2+15-) and suppressor (bright Leu 2+15+) cell populations are elevated in homosexual men. Homosexual men who have been exposed to human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) have higher numbers of Leu 2+15- and Leu 2+7- cells than homosexual men who have not been exposed. Phenotypic subpopulations (dim Leu 2+ Leu 15+ and Leu 7-11+) that are associated with the most potent natural killer activity (against K562 target cells) were not found to be elevated in homosexual men.

Antibodies, Monoclonal↗
PubMed1986

NMR studies of crab and plaice metallothioneins.

Metallothioneins isolated from the hepatopancreas of the edible crab (Cancer paqurus) and the plaice (Pleuronectes platessa) after cadmium injection are predominantly cadmium proteins containing only small amounts of zinc and traces of copper. The removal of metal ions from the two metallothioneins by EDTA was studied using proton NMR spectroscopy. The rates of removal of cadmium and zinc were monitored directly from the intensity of the resonances due to the cadmium and zinc-EDTA complexes. Nearly all the zinc present in the protein was extracted by EDTA relatively rapidly, whereas only 10 to 20% of the total cadmium was removed in at least three steps. The total (Cd + Zn) metal removed at equilibrium was 1.2 to 1.8 g-ions/mole protein. Information on conformational changes in the protein were also obtained from studying alterations in the proton resonances of the protein. This was directly correlated with removal of metal from the protein. The coordination environments of the cadmium ions in crab metallothionein were investigated by using 113Cd-NMR, and compared with 113Cd-NMR spectra of rabbit liver MT-II and Scylla serrata MT-I.

Animals↗
PubMed1985

Human T-lymphotropic retrovirus type III/lymphadenopathy-associated virus antibody. Association with hemophiliacs' immune status and blood component usage.

We studied the human T-lymphotropic retrovirus type III/lymphadenopathy-associated virus (HTLV-III/LAV) antibody status of 234 factor VIII concentrate recipients, 36 factor IX concentrate recipients, 69 long-term recipients of frozen packed red blood cells, and 47 persons not receiving routine transfusion therapy. Factor VIII concentrate recipients had a significantly higher rate of seropositivity (74%) than any other group. Factor IX concentrate recipients had a significantly higher rate (39%) than recipients of frozen packed red blood cells (4%) or nontransfused persons (4%). In factor VIII concentrate recipients, HTLV-III/LAV seropositivity was significantly associated with more severe hemophilia, greater factor dosage, elevated immunoglobulin and immune complex levels, lower T-helper lymphocyte numbers, and lower ratios of T-helper to T-suppressor lymphocytes. For factor IX concentrate recipients, seropositivity was associated with more severe hemophilia. Antibody-positive factor IX concentrate recipients had a lower rate of seropositivity to HTLV-III/LAV p41 membrane antigen than did antibody-positive factor VIII concentrate recipients, but factor VIII and factor IX concentrate recipients had similar rates of seropositivity to core antigens. We conclude that both factor VIII and factor IX concentrates may transmit HTLV-III/LAV. For factor VIII recipients, HTLV-III/LAV seropositivity is associated with altered immune test results.

Adolescent↗
PubMed1985

113Cd NMR studies of reconstituted seven-cadmium metallothionein: evidence for structural flexibility.

A reproducible method for the reconstitution of rabbit liver metallothionein (MT) containing seven cadmium atoms per mole of protein is described. This protein was studied in detail by 113Cd NMR at 88-, 55-, and 44-MHz frequencies, including the effects of pH, temperature, and ionic strength on the spectra. Our results differ significantly from previous reports of 113Cd NMR on similar samples. Thus, the spectra of both chromatographically distinguishable isoforms MT1 and MT2 were not identical, and neither could be interpreted in terms of a unique static model with the seven Cd ions forming two independent clusters of four and three Cd ions. Large differential shifts of 113Cd resonances were observed with changes in temperature over the range 277-320 K and ionic strength (0.02-0.5 M). At low temperature a slow structural change (half-life of several minutes) was detected. The structure was more rigid at high ionic strength. The frequency dependence and two-dimensional J-resolved spectra revealed that 113Cd resonances were composed of several overlapping peaks, complicating the interpretation of fine structure in one-dimensional spectra. A new flexible model of the Cd cluster in metallothionein is proposed. This model incorporates dynamic thiolate exchange reactions and involves several configurational substates of the protein. The possible relationship of such flexibility to the function of metallothionein is discussed.

Animals↗
PubMed1985

Immune complexes in the acquired immunodeficiency syndrome (AIDS): relationship to disease manifestation, risk group, and immunologic defect.

Immune complex assays (and other immunologic tests) were performed on sera from 162 patients with the acquired immunodeficiency syndrome (AIDS) and 275 AIDS-related subjects. Immune complexes were detected in 89% of AIDS patients and 93% of homosexual men with lymphadenopathy. Immune complex levels in AIDS patients were not associated with a particular risk group or with types of opportunistic infection or malignancy; however, they correlated with other laboratory features of the immune defect (depression in T helper cells and T helper/suppressor-cell ratio, and IgG levels). Immune complexes were also detected in a lesser proportion of risk-group controls (homosexual men, hemophiliacs, Haitians). In risk-group controls, immune complex levels were associated with certain features reflecting sexual practice, blood product exposure, or infection, but these features did not account for the higher levels found in AIDS patients. In appropriate situations, immune complex assays may be of value as screening tests or, possibly, as prognostic indicators for AIDS or AIDS-related syndromes.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Alterations of functional subsets of T helper and T suppressor cell populations in acquired immunodeficiency syndrome (AIDS) and chronic unexplained lymphadenopathy.

We have studied the distribution of Leu8 and Ia on T cells of the helper (T4) and suppressor (T8) phenotype in homosexual men with chronic unexplained lymphadenopathy, homosexual men with the acquired immunodeficiency syndrome (AIDS), and homosexual and heterosexual controls. Decreased numbers of helper T cells in lymphadenopathy patients are due to a decrease in the T4:Leu8+ subset, whereas in AIDS patients, both the T4:Leu8+ and the T4:Leu8- subsets were decreased.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Exposure to human T-lymphotropic virus type III/lymphadenopathy-associated virus and immunologic abnormalities in asymptomatic homosexual men.

Immunologic and serologic studies were done in 120 homosexual men who reportedly had no symptoms related to the acquired immunodeficiency syndrome. Forty-nine men (41%) had antibody to the retrovirus human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV), and 37 (31%) had an abnormal T-cell subset ratio and other immunologic abnormalities. These abnormalities were almost exclusively confined to men seropositive for the retrovirus. Multivariate statistical analysis showed that exposure to HTLV-III/LAV was the single best predictor of T-cell (and other) immunologic abnormalities. Sexual practice, particularly receptive anal intercourse, predicted exposure to HTLV-III/LAV but was not independently related to T-cell abnormalities. The association of other microbial serologic findings with HTLV-III/LAV seropositivity or T-cell changes was a coincidental function of sexual activity. Immunologic abnormalities in asymptomatic homosexual men are mostly related to exposure to HTLV-III/LAV.

Antibodies, Viral↗
PubMed1985

Proton NMR spectra of urine as indicators of renal damage. Mercury-induced nephrotoxicity in rats.

Rats were injected intraperitoneally with HgCl2 at doses of 2.5, 5, 7.5, and 10 mumol of Hg/kg. Urine was collected over a 24-hr period. At this time, plasma samples were taken and kidney damage was assessed by histological examination. Urinary gamma-glutamyltransferase levels were significantly elevated at Hg2+ doses of 7.5 and 10 mumol/kg, consistent with the detection of acute tubular necrosis by light microscopy. Resonances for a large number of low molecular weight metabolites were assigned in high resolution 1H NMR spectra of rat urine. Spectra from small volumes of urine (about 0.5 ml) were obtained in less than 5 min with no pretreatment. Significant Hg2+ dose-related decreases in the excretion of creatinine and citrate and increases of glucose, glycine, alanine, alpha-ketoglutarate, succinate, and acetate were detected. Elevated levels of lactate and creatinine in plasma of rats receiving the two highest doses were found by 1H NMR. There was a good correspondence between the histopathology, enzyme excretion, and 1H NMR urinary metabolite fingerprints in the assessment of Hg2+-induced renal damage. 1H NMR provided a sensitive measure of mercury-induced nephrotoxic lesions, and information on the molecular basis of mercury cytotoxicity was derived from the abnormal patterns of metabolite excretion. These suggested that primary metabolic effects of mercury were upon mitochondrial metabolism, in particular inhibition of certain citric acid cycle enzymes leading to decreased utilization of alpha-ketoglutarate and succinate by the renal tubular cells. The decrease in urinary citrate associated with Hg2+ dosing was attributed to intracellular, tubular acidosis with concomitant enhanced citrate reabsorption. The acidosis was assumed to arise from a combination of the inhibition of tubular carbonic anhydrase and a mild metabolic lactic acidosis due to increased activity of anaerobic pathways in the kidney. The possible extension of the 1H NMR techniques to the investigation of the nephrotoxic potential of other compounds and drugs is discussed.

Animals↗
PubMed1985

Cellular tropism of the human retrovirus HTLV-III/LAV. I. Role of T cell activation and expression of the T4 antigen.

In cultures of normal human lymphocytes infected with the human retrovirus HTLV-III/LAV, detectable cytoplasmic virus appears and then disappears in a proportion (1 to 10%) of cells, followed by release of virus detected by particulate reverse transcriptase activity, virus antigen assay, and infectivity titer. Virus infection is associated with loss of detectable T4 antigen on infected cells and, ultimately, complete loss of T4+ cells from the culture. Residual non-T4+ cells are not susceptible to a second infection with HTLV-III/LAV, and in cultures of separated cell populations, substantial virus replication occurred in T4+ T cells and minimally, if at all, in non-T4+ cells. We could not detect a disproportionate loss of cell surface phenotype (other than T4) in comparison of infected and noninfected cultures of lymphocytes or purified T4+ T cells when these cultures were monitored with a panel of monoclonal antibodies that detect the major mononuclear cell types (alpha-T11, alpha-T3, alpha-Mo2, alpha-B1), functional T cell subsets (alpha-T8, alpha-Leu-8, alpha-T17), or activated/proliferating cells (alpha-T10, alpha-Ia, alpha-T9, alpha-4F2, alpha-Tac). HTLV-III/LAV replication was quantitatively greatest in lymphocytes stimulated with phytohemagglutinin (PHA) and cultured in the presence of interleukin 2 (IL 2). Once activated by PHA, virus production in nondividing (irradiated) cells was similar to that in nonirradiated cells, but was substantially reduced if radiation was performed before PHA stimulation. Omission of PHA, IL 2, or both resulted in progressively lower amounts of virus replication. However, virus replication was detected and T4+ T cell depletion occurred in all cultures, regardless of medium supplement or radiation. T4+ T cells absorb infectious virus, and the binding of HTLV-III/LAV to the surface of T4+ T cells, but not to non-T4+ cells, was directly demonstrated. Binding is equivalent in activated and nonactivated cells and at 4 degrees and 37 degrees C. Reciprocal inhibition of binding was observed with alpha-T4a monoclonal antibody and virus. Exposure of cells to alpha-T4a before and during HTLV-III/LAV inoculation inhibited subsequent virus replication. We conclude that T4+ T cells are the major target for HTLV-III/LAV replication, that this tropism is related to expression of the T4 antigen that serves as a binding site for virus, that infection is inexorable in T4+ T cells regardless of subset or activation state, and that the activation/proliferative state of the cells is not a necessary determinant of infectivity, but rather, determines the amount of replication that will ensue.

Adsorption↗
PubMed1985

Screening tests for blood donors presumed to have transmitted the acquired immunodeficiency syndrome.

We investigated 18 sets of blood donors from 12 to 50 months after they donated blood to recipients who subsequently developed the acquired immunodeficiency syndrome (AIDS). Within each donor set, only one donor was suspected of having transmitted the disease (ie, member of an AIDS risk group). The other donors (n = 189) were not risk group members and served as controls. A number of laboratory tests distinguished suspected from nonsuspected donors, including determination of T helper/T suppressor cell ratio, antibody to hepatitis B core antigen, and immune complexes, but none of these was as sensitive and specific as tests for antibody to the human retrovirus, HTLV-III/LAV.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Two-dimensional proton nuclear magnetic resonance "maps" of acetaminophen metabolites in human urine.

Two-dimensional proton-proton correlated NMR spectra of concentrated urine from a subject who had ingested a 1-g dose of acetaminophen are reported. These "maps" provide a considerable simplification of the spectrum in comparison with conventional one-dimensional NMR spectra. In the present case, peaks for all the major acetaminophen metabolites, including the L-cysteinyl conjugate, can be unambiguously assigned.

Acetaminophen↗
PubMed1985

A high resolution proton nuclear magnetic resonance approach to the study of hepatocyte and drug metabolism. Application to acetaminophen.

1H spin echo NMR spectra of intact hepatocytes, isolated from rat liver, showed resonances for glucose, mobile fatty acids, and +N(CH3)3 groups including choline headgroups of phosphoglycerides. Spectra from extracts of the same cells contained many more well resolved resonances due to low Mr metabolites. These included signals for free amino acids, ketone bodies, glucose, lactate, and acetate. 1H NMR spectra from suspensions of intact hepatocytes incubated with acetaminophen showed no resonances for drug metabolites, although changes in sugar resonances were observed. However, spectra of extracts from acetaminophen-treated hepatocytes contained resonances for both acetaminophen itself and its major metabolites, the glucuronide and sulfate conjugates. Results on the extent of acetaminophen metabolism as measured by 1H NMR compared well with previously reported chromatographic studies. The rate of metabolism of acetaminophen by hepatocytes was much slower in 2H2O buffer compared to H2O buffer and selective deuteration of several metabolites including the ketone bodies, glucose, and acetaminophen glucuronide was observed. The deuteration of glucose C2H appeared to be due to futile cycling of the glycolytic pathway to at least fructose 6-phosphate, and incorporation of deuterium by the enzyme phosphoglucoisomerase. This work demonstrates that 1H NMR studies of intact hepatocytes and cell extracts together can provide considerable insight into the metabolism of acetaminophen in vitro. Little pretreatment of samples is required, results can be obtained rapidly, and both normal and drug metabolites can be observed simultaneously. Similar studies should be applicable to a wide range of other drugs.

Acetaminophen↗