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Biomedical subjects

J Ni

Publications and source records attributed to J Ni.

At least 199 records · Page 11Linked to original sources
PubMed1995

Adhesion molecule expression and adhesion properties of murine intestinal intraepithelial lymphocyte hybridomas.

We used mouse intraepithelial lymphocyte hybridomas (IELH) to study the role of adhesion molecules, especially beta 7 integrins, in the adherence of IELH to intestinal epithelial cells. Unstimulated 9.1 gamma delta IELH cells expressed high levels of CD11a, CD11a/CD18, CD44, and CD45; medium levels of CD45RB and integrin alpha 4; low levels of alpha M290, beta 7, and 33D1; and very low levels of ICAM-1 and VCAM-1. PHA and TGF-beta stimulated IELH cells--but not control BW5147 cells (alpha 4/beta 7 integrin negative fusion partner)--to bind to IEC-18 and CMT-93 intestinal epithelial cells, but not to renal mesangial cells. The binding was partially blocked by mAbs to integrin alpha 4 and/or alpha M290. The two mAbs in combination did not completely block the binding, suggesting that epitopes not recognized by these two mAbs are also involved in binding. The adhesion of 9.1 gamma delta cells to IEC-18 cells was also partially inhibited by mAbs to VCAM-1, LFA-1, and CD44, but not by mAbs CD45 and a control rat IgG. Thus, IELH may be a useful model system with which to study the role of adhesion molecules in the interaction between IEL and intestinal epithelial cells.

Animals↗
PubMed1995

Antisense snoRNAs: a family of nucleolar RNAs with long complementarities to rRNA.

A growing subset of small nucleolar RNAs (snoRNAs) contains long stretches of sequence complementarity to conserved sequences in mature ribosomal RNA (rRNA). This article reviews current knowledge about these complementarities and proposes that these antisense snoRNAs might function in pre-rRNA folding, base modification and ribosomal ribonucleoprotein assembly, in some cases acting as RNA chaperones.

Animals↗
PubMed1994

Progressive cognitive impairment following chronic cerebral hypoperfusion induced by permanent occlusion of bilateral carotid arteries in rats.

The effects of chronic cerebral hypoperfusion induced by permanent occlusion of bilateral common carotid arteries (2VO) on learning and memory performance were examined in rats using an eight-arm radial maze task. The learning of the task was severely impaired in the permanent 2VO rats that had not been pretrained, while the retention was slightly impaired and soon recovered in the permanent 2VO rats that had been fully pretrained when tested within 1 month after the 2VO operation. The performance, however, was impaired in the pretrained rats when a 3-min delay was interposed between the fourth and fifth choices. Moreover, when retrained in the radial maze 4 months after the permanent 2VO, these same rats showed a performance impairment. Some loss of the hippocampal pyramidal neurons was observed 1 month after the permanent 2VO, although the decrease was not significant. However, significant loss of the cells was observed in the hippocampus CA1 subfield 4 months after the operation. We concluded that: (1) In the early stage (1 month after permanent 2VO), a learning deficit was observed in the non-pretrained rats. In the pretrained rats, working memory was not impaired, whereas longer term memory was compromised; (2) in the late stage (4 months after permanent 2VO), working memory may have also been impaired in the pretrained rats; and (3) this progressive cognitive deficit seemed to parallel the progress of neuronal damage.

Animals↗
PubMed1994

Acute myocarditis. Rapid diagnosis by PCR in children.

BACKGROUND: The diagnosis of viral myocarditis remains difficult and generally depends on clinical and histological criteria. Viral cultures and serology are often unrewarding, with low yields. The purpose of this study was to analyze the usefulness of polymerase chain reaction (PCR) in the rapid diagnosis of acute myocarditis in children. METHODS AND RESULTS: PCR was used to analyze 38 myocardial tissue samples from 34 patients with suspected acute viral myocarditis and 17 control patients with congenital heart disease (14) or hypertrophic cardiomyopathy (3). Myocardial samples were obtained at the time of right ventricular biopsy (13 samples), from explanted hearts (18 samples) at transplantation, and from cardiac autopsy specimens (24 samples) and were evaluated for the presence of enterovirus, cytomegalovirus (CMV), adenovirus, and herpes simplex virus (HSV) using PCR primers designed to consensus and unique sequences of these viral genomes. Blood also was obtained at the time of biopsy (11) or transplant (18). In 26 of 38 myocardial samples (68%), viral genome was detected by PCR (15 adenoviral, 8 enteroviral, 2 HSV, 1 CMV), whereas all control myocardial samples and blood samples were negative. Four patients had positive viral cultures, and these matched the PCR findings. Disagreement with histopathology occurred in 13 of 26 PCR-positive specimens, usually associated with adenovirus. CONCLUSIONS: PCR offers a rapid, sensitive diagnostic method for myocardial viral infection. While enterovirus is an important etiological agent, adenovirus was more prevalent in this series and should be evaluated when etiology is sought. PCR used in conjunction with standard endomyocardial biopsy appears to enhance the likelihood of detecting viral genome in the myocardium of patients with clinical evidence of myocarditis.

Acute Disease↗
PubMed1994

Effects of sarcoplasmic reticulum calcium pump inhibitors on vascular smooth muscle.

A dysfunctioning of Ca2+ pump ATPase in the sarcoplasmic reticulum in vascular smooth muscle has been proposed as a contributing factor for the development of genetic hypertension. In this study, we determined whether in vitro inhibition of the sarcoplasmic reticulum Ca2+ pump in vascular smooth muscle tissues and cultured cells isolated from aortas of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats would elicit the known alterations of contractile function and cell growth. We found the following common vascular effects of thapsigargin and cyclopiazonic acid, which are known to be selective inhibitors of sarcoplasmic reticulum Ca(2+)-ATPase in a number of tissues including smooth muscle: (1) Both sarcoplasmic reticulum Ca2+ pump inhibitors diminished agonist-induced transient contraction in Ca(2+)-free medium (ie, contraction due to intracellular release of Ca2+) and enhanced nifedipine-sensitive contraction on readmission of Ca2+ (ie, Ca2+ influx via L-type channels); and (2) thapsigargin and cyclopiazonic acid inhibited the attachment of cultured aortic muscle cells to the substrate in a similar degree in both SHR and WKY cells, but SHR cells were more sensitive than WKY cells to the inhibition of cell proliferation by these two agents. The first effect may provide an explanation for several contractile abnormalities known to be associated with elevated cytosolic Ca2+ concentration, whereas the second effect suggests that elevation of cytosolic Ca2+ in aortic smooth muscle cells is not necessarily associated with or sufficient to account for the accelerated cellular proliferation in SHR. These results, however, further stress the functional importance of impairment of Ca2+ regulation in vascular smooth muscle cells in genetic hypertension.

Animals↗
PubMed1993

SnR31, snR32, and snR33: three novel, non-essential snRNAs from Saccharomyces cerevisiae.

Genes for three novel yeast snRNAs have been identified and tested for essentiality. Partial sequence information was developed for RNA extracted from isolated nuclei and the respective gene sequences were discovered by screening a DNA sequence database. The three RNAs contain 222, 188 and 183 nucleotides and are designated snR31, snR32 and snR33, respectively. Each RNA is derived from a single copy gene. The SNR31 gene is adjacent to a gene for an unnamed protein associated with the cap-binding protein eIF-4E. The SNR32 gene is next to a gene for ribosomal protein L41 and the gene for SNR33 is on chromosome III, between two open reading frames with no known function. Genetic disruption analyses showed that none of the three snRNAs is required for growth. The new RNAs bring the number of non-spliceosomal snRNAs characterized thus far in S. cerevisiae to 14, of which only three are essential.

Base Sequence↗
PubMed1993

Multiparameter flow cytometric analysis of a novel cytotoxin (factor 2) induced tumor cell membrane permeability.

An improved twin-probe multiparameter flow cytometric technique was applied to examine a novel cytotoxin, Factor (F2), induced tumor cell permeability. Ability to retain preloaded intracellular bis-carboxyethyl carboxyfluorescein (BCECF, green fluorescence) and to exclude extracellular propidium (red fluorescence) was measured simultaneously with forward and right-angle scatter. In addition to the two expected cell populations which were stained green negative, red positive ("membrane-damaged" and "non-viable", Region 2), and green positive, red negative ("membrane intact" and "viable", Region 3), a third population was seen which fluoresced neither green nor red and displayed intermediate light scatter characteristics (Region 1). K562 cells progressed from Region 3 to Region 1, and then from Region 1 to Region 2 after treatment with F2. These results suggest that sequential changes in membrane structure lead to increased permeability, first with respect to intracellular BCECF and then in turn to extracellular propidium. Flow cytometric changes caused by F2 were detectable 10 min after treatment with 2.5 U/ml of F2, and 5 min after 10 or 40 U/ml of F2. Flow cytometric analysis showed that F2-induced tumor cell lysis and growth inhibition were accompanied by rapid alternations in tumor cell membrane permeability. Flow cytometric analysis also distinguished F2 cytotoxicity from phorbol myristate acetate (PMA) associated cytotoxicity to K562 cells and determined that F2 produced spontaneously or induced by PMA and/or ciprofloxacin had a similar ability to induce tumor cell membrane permeability change.

Cell Membrane Permeability↗
PubMed1993

Isolation of a novel cytotoxic lymphokine (factor 2) from a human B-cell line (Karpas 160b) by preparative isoelectric focusing in the rotofor cell and chromatofocusing.

Preparative isoelectric focusing (IEF) using a Rotofor cell was used for the isolation of a biologically active form of a novel cytotoxic lymphokine (Factor 2, F2) produced by a human B-cell line (Karpas 160b). We found that F2 either purified by DE52 or extracted from 160b cells using CHAPS, after adding octyl glucoside to 0.05%, could be electrofocused in the Rotofor cell without the addition of carrier ampholytes. Better recovery and separation were also achieved in the presence of 0.5% CHAPS, 3M urea. We compared the fractionation of F2 by chromatofocusing and IEF in Rotofor. Our results also showed that F2 was separable from tumor necrosis factor and phorbol myristate acetate-associated cytotoxicity by one step IEF in Rotofor. F2 purified by DE52, S-300 and Mono Q was further purified by IEF in Rotofor.

B-Lymphocytes↗
PubMed1993

Urinary excretion of hexafluoroisopropanol glucuronide and fluoride in patients after sevoflurane anaesthesia.

The excretion of sevoflurane metabolites in the urine collected every 12 h after sevoflurane anaesthesia was measured by ion exchange chromatography. A metabolite, which was converted on incubation with glucuronidase to hexafluoroisopropanol was detected in the urine. The maximum excretion was found in the first 12 h after anaesthesia, none was found in the last collection 3 days after anaesthesia. The excretion half-life for the metabolite was calculated to be 55 h. A significant increase in the urinary excretion of organic and inorganic fluoride was also observed during the first 12 h after anaesthesia. The cumulative organic and inorganic fluoride excretion in the 3 days after sevoflurane anaesthesia was 1588 and 856 mumol, respectively (ratio = 1.85). The excreted half-lives for organic and inorganic fluoride were calculated to be 4028 and 2069 min, respectively. Our study showed that a hexafluoroisopropanol glucuronide is excreted in the urine, and the major part of urinary metabolites of sevoflurane, organic and inorganic fluoride, are excreted within 2 days of sevoflurane inhalation in man.

1-Propanol↗
PubMed1993

[The study of the RFLP of D14S13 site of human genome].

The single-locus probe pCE 1.2 recognizes the D14S13 site in human genome. Allele-frequency of HaeIII digested D14S13 site is drawn out from 269 unrelated individuals. It displayed that there were at least 66 alleles and more than 93% heterogeneity. No mutation in 93 individuals of 8 families was observed. This RFLP technique has been applied in the identification and parentage testing in forensic science, and the accuracy of identity was calculated. Some further applications were discussed.

Alleles↗
PubMed1992

Production and induction of a novel cytotoxin (factor 2) by a human B-cell line.

The human B-cell line, Karpas 160, was found to produce Factor 1 and 2 (F1 and F2). F1 was found to be indistinguishable from tumor necrosis factor beta (TNF-beta), while F2 appears to be a new cytotoxin. We used several stimuli alone or in combination to trigger the 160b cells, a subclone of Karpas 160, to produce higher yield of F2. The optimal culture times, concentrations of cells and a range of stimuli were studied. We found that 20-25 ng/ml of phorbol myristate acetate (PMA) effectively induced the higher production of F2. Pretreatment of the cells with sodium butyrate enhanced F2 production. Production of TNF but not F2 was inhibited when the cells were cultured with tunicamycin and PDB. When ciprofloxacin or cycloheximide was added to the medium, F2 production in the presence of PMA was amplified. When 160b cells were cocultured with K562 cells, low levels of F2 induction were observed. We found that most types of human tumor cell lines were highly susceptible to F2, but less sensitive or even resistant to TNF. In contrast, normal human cell lines were not susceptible to F2. Therefore, it appears that F2 could be a new human cytotoxin.

B-Lymphocytes↗
PubMed1992

Characterization and partial purification of a novel cytotoxic lymphokine (factor 2) produced by a human B cell line (Karpas 160).

A subclone (160b) of the human B cell (Karpas 160) was shown to produce a novel cytotoxic lymphokine [Factor 2 (F2)] in addition to tumour necrosis factor alpha (TNF-alpha) and beta (TNF-beta). F2 was found to have selective toxicity to numerous human tumour cell lines, particularly the erythroleukaemic cell line K562, whereas TNF-alpha/beta were not cytotoxic to these cells, even at relatively high concentrations. Our studies have shown that F2 activity in crude preparations is heterogeneous both in its molecular weight, isoelectric point (pI) and hydrophobicity, which depends not only on the source of F2 cytotoxicity but also on the conditions of methods for its production. Our studies also showed that F2 was separable from TNF by DE52, S-300 gel filtration and Rotofor isoelectric focusing. F2 was partially purified up to 1000-fold by two procedures. The major active form, as assessed by gel filtration was of mol. wt of 45-67 kDa. On SDS-PAGE, F2 activity was recovered mainly from two regions of the gels corresponding to 10-14 kDa and 60-70 kDa. Antibodies of human TNF-alpha, TNF-beta, IFN-alpha, IFN-gamma, and TGF-beta failed to prevent F2-mediated cytotoxicity to K562. F2 activity was not inhibited by mannose-6-PO4 or mouse mAb to rat granule content, both of which have been reported to block human natural killer cytotoxic factor. Our studies indicated that F2 is likely to be a distinct human cytokine with selective cytotoxic activity against tumour cells.

B-Lymphocytes↗
PubMed1992

Relationship between a novel human cytotoxin (factor 2) produced by a B cell line (Karpas 160) and phorbol-myristate-acetate-associated cytotoxicity.

We found that 160b cells, a subclone of Karpas 160 human B cell line, spontaneously secreted a novel cytotoxin, factor 2 (F2). F2 was also extracted from the cells by 60% ammonium sulphate, 0.5% CHAPS and 0.28% Triton X-114. We were able to show that phorbol myristate acetate (PMA) greatly enhanced the production of F2, and PMA may also account for part of the putative F2 cytotoxic activity to K562 cells in crude preparations. We compared the cytotoxic effect of F2 with PMA-associated F2-like cytotoxicity to K562 cells as well as the adequacy of our schemes to purified F2 with regard to its separation from PMA. We found that it was possible to separate PMA from F2 preparations by gel filtration and Rotofor preparative isoelectric focusing. The fate of PMA was also monitored with 3H-PMA and chromatographic profiles of 3H-PMA were studied using DE52 and gel filtration chromatography. We were able to establish that less than 2.9% of the cytotoxicity to K562 was due to PMA. We also found that the radioactive peaks and cytotoxicity peaks to K562 were not well correlated, indicating that the cytotoxicity was not mainly due to remaining PMA. Activated charcoal removed virtually all F2 and PMA but not tumour necrosis factor activity. Our results also showed that cytotoxicity to K562 resulting from F2 or PMA-associated proteins had different physicochemical properties, indicating that they are different molecular entities. These findings are consistent with the earlier observation that 160 cells produce F2 spontaneously and that PMA can amplify its production significantly.

B-Lymphocytes↗