Search PubMed⌕ Search

Biomedical subjects

K C Chen

Publications and source records attributed to K C Chen.

At least 127 records · Page 7Linked to original sources
PubMed1985

Response of the isolated heart to carbon monoxide and nitrogen anoxia.

The effects of carbon monoxide (CO) or nitrogen (N2) anoxia were assessed and compared in stimulated (360 beats/min) and unstimulated isolated rat hearts. The hearts were perfused through the aorta with Krebs-Henseleit solution aerated with 95% O2-5% CO2 (O2). Heart rate, pulse pressure, perfusate flow, and perfusate lactate concentrations were recorded. After 30 min of O2 perfusion, the hearts were challenged with 95% CO-5% CO2 (CO) or 95% N2-5% CO2 (N2) for 10 min. The preparations were then reoxygenated and allowed to recover for 10 min. In the unstimulated hearts, CO depressed heart rate, pulse pressure, and perfusate flow earlier than did N2. Lactate concentrations increased to a greater extent with N2 than with CO. With reoxygenation heart rate, pulse pressure, and lactate concentrations returned to control values earlier in the CO hearts. The differences observed in pulse pressure and lactate concentrations with CO and N2 anoxia disappeared with stimulation. There were no significant differences in water or glycogen contents after CO or N2 in either the unstimulated or stimulated preparations. These results suggest that CO may have a direct effect on the myocardium in addition to its well-known anoxic effect.

Animals↗
PubMed1985

Fusion of an immunoglobulin variable gene and a T cell receptor constant gene in the chromosome 14 inversion associated with T cell tumors.

An inversion of chromosome 14, inv(14)(q11,q32), is frequently observed in human T cell tumors; the cytogenetic breakpoints are of interest because the T cell receptor alpha-chain and immunoglobulin heavy chain genes reside on chromosome bands 14q11 and 14q32, respectively. We have investigated the structure of the alpha-chain genes in a T cell line harboring the chromosome 14 inversion. On the normal chromosome 14, a V alpha segment has rearranged nonproductively with a J alpha segment. In contrast, the inverted chromosome features an unprecedented rearrangement in which an immunoglobulin heavy chain variable gene segment (VH) on chromosome band 14q32 has joined with a J alpha segment from band 14q11. The VH-J alpha C alpha rearrangement is productive at the genomic level and therefore may encode a hybrid immunoglobulin/T cell receptor polypeptide.

Alleles↗
PubMed1985

Vaginal redox potential in bacterial vaginosis (nonspecific vaginitis).

To explore of the association of bacterial vaginosis with anaerobic bacterial growth in the vagina, we measured the redox potential (Eh) at the vaginal epithelial surface of women with this syndrome. Among normal women, the value for Eh in the vagina ranged from +322 mV to +137 mV (mean, +170 mV); whereas among women with bacterial vaginosis, the Eh ranged from +71 mV to as low as -257 mV (mean, -92 mV). Following successful treatment of the vaginosis with metronidazole, the vaginal Eh increased to a mean of +208 mV. Thus, the low redox potential in the vagina during bacterial vaginosis appears to be due to microbial metabolism in the vagina and does not represent a persistent host factor responsible for the anaerobic vaginal flora. Any host factors responsible for bacterial vaginosis remain to be elucidated.

Bacteria, Anaerobic↗
PubMed1985

Blind pouch syndrome: a case report.

The blind pouch syndrome is associated with a spectrum of diseases affecting the gastrointestinal tract that includes: malabsorption, ulceration, bleeding, and perforation. The clinical signs and symptoms of anemia, weight loss, abdominal pain, vomiting, and intermittent intestinal obstruction can be found. Occasionally, constipation or more often diarrhea is an important manifestation. A case report of this entity with related radiological and pathological findings secondary to a side-to-side anastomosis is presented and discussed.

Adolescent↗
PubMed1984

Effect of intermittent carbon monoxide inhalation on erythropoiesis and organ weights in rats.

Sprague-Dawley rats were exposed to 450 ppm carbon monoxide (CO) for 6 h per day, 5 days per week for 33 days. The effect of CO on reticulocyte count, hematocrit, hemoglobin concentration, body weight and selected organ weights was measured. Exposure to CO caused a three-fold increase in the youngest reticulocyte population, concomitant with an increase in the total reticulocyte count. Despite continued CO exposure, reticulocyte number and distribution returned to normal by day 9, suggesting that reticulocyte response of the organism to CO had changed. Both hematocrit and hemoglobin concentrations began to increase 16 days after CO exposure and remained at the increased level for the duration of the exposure period. There were no changes in kidney, liver and adrenal weights throughout the course of study. However, spleen weight was increased after 5 days of CO exposure. Left and right ventricular organ weight ratios increased equally at the same time during the study. These results indicate that the increase in the young reticulocyte population and the subsequent increase in total reticulocyte count are the earliest erythropoietic responses to intermittent CO exposure and that CO-induced polycythemia is associated with cardiac hypertrophy in rats.

Aerosols↗
PubMed1984

Rapid, inexpensive method for specific detection of microbial beta-lactamases by detection of fluorescent end products.

A rapid method was developed for specific detection of microbial beta-lactamases which uses ampicillin and cephalexin as substrates. The end products (open beta-lactam ring forms) generated after separately incubating either substrate with beta-lactamase-producing organisms initially were separated from the unhydrolyzed substrates by high-voltage electrophoresis at pH 2.1. The end products of both antibiotics were highly fluorescent and could be analyzed visually and semiquantitatively under a long-wave UV lamp. Application of 5 microliters of the same incubation mixture onto filter paper without subsequent electrophoretic separation also resulted in development of fluorescence after brief heating at 120 degrees C for 5 min. This spot test differentiates penicillinase activity from cephalosporinase activity and distinguishes between beta-lactamase and acylase activities, since the end products of acylase [the common side chain, D(-)-alpha-aminophenylacetic acid, and the intact beta-lactam nuclei, 6-aminopenicillanic acid and 7-aminodeacetoxycephalosporanic acid] are not fluorescent. This method was relatively rapid, inexpensive, and more sensitive than the chromogenic cephalosporin (nitrocefin) method when 21 strains of 7 gram-positive species and 77 strains of 29 gram-negative species of bacteria were tested.

Amidohydrolases↗
PubMed1984

Aryl hydrocarbon hydroxylase induction in rat pulmonary alveolar macrophages (PAMs) by diesel particulates and their extracts.

The Aryl hydrocarbon hydroxylase (AHH) activity in the lavaged PAMs was investigated in male Fischer rats after inhalation of diluted diesel exhaust (DE), and compared with intratracheal instillation of the organic solvent extract of hydrocarbons adsorbed on the particulate surface. Animals were exposed to concentrations of 1500 micrograms/m3 or 6000 micrograms/m3 of diesel particulates, 20 hrs/day, 7 days/wk for 2 days up to 28 days, or treated with a single intratracheal dose of DE extract or benzo[a]pyrene (B[a]P) dissolved in gelatin-saline solution. The counts of lavageable PAM and polymorphonuclear leukocytes (PMN) were significantly elevated in the exposed rats. However, a decrease of AHH activity was found in the PAM cells after four weeks of exposure to both particulate concentrations. The AHH activity in the PAMs from rats injected intratracheally with 5 mg/kg of B[a]P was slightly increased; no change was observed in PAMs similarly treated with DE extract. Enzyme induction is not noted because of absence of sufficient quantities of hydrocarbons need for induction. This could be further potentiated that macrophages metabolize and perhaps reduce hydrocarbon levels by translocation.

Animals↗
PubMed1984

Bacterial vaginosis during pregnancy. An association with prematurity and postpartum complications.

Although bacterial vaginosis (BV) is a common disorder associated with high concentrations of potentially pathogenic micro-organisms, BV has not yet been linked to infections outside the vagina. To investigate the association of BV with adverse outcomes during or following pregnancy, we analysed the prevalence of BV among women with and without premature labor, and early-onset postpartum endometritis. Bacterial vaginosis was identified by gas-liquid chromatographic criteria in 28 (49%) of 57 women giving birth at less than or equal to 37 weeks gestation or with birthweight less than 2500 g and in 27 (24%) of 114 women bearing an infant at term (p = 0.001). Organisms associated with BV, such as Gardnerella vaginalis, anaerobic bacteria, and/or genital mycoplasmas, were recovered from the endometrium of 61 of 101 women with clinical signs of endometritis. G. vaginalis was the most frequent isolate from both the endometrium (38 patients) and the blood (8 patients) of women with postpartum endometritis. Bacteroides bivius was the most frequent anaerobic isolate from the endometrium (11 cases) and blood (4 cases). Patients with both G. vaginalis and anaerobes isolated remained febrile significantly longer after beginning antibiotic therapy than did other patients (57.1 hours. vs. 36.3 hours, p = 0.02). These data suggest that BV may be associated with prematurity and that BV may contribute to postpartum maternal infectious morbidity.

Bacteria, Anaerobic↗
PubMed1983

Nonspecific vaginitis. Diagnostic criteria and microbial and epidemiologic associations.

Numerous previous studies of nonspecific vaginitis have yielded contradictory results regarding its cause and clinical manifestations, due to a lack of uniform case definition and laboratory methods. We studied 397 consecutive unselected female university students and applied sets of well defined criteria to distinguish nonspecific vaginitis from other forms of vaginitis and from normal findings. Using such criteria, we diagnosed nonspecific vaginitis in up to 25 percent of our study population; asymptomatic disease was recognized in more than 50 percent of those with nonspecific vaginitis. A clinical diagnosis of nonspecific vaginitis, based on simple office procedures, was correlated with both the presence and the concentration of Gardnerella vaginalis (Hemophilus vaginalis) in vaginal discharge, and with characteristic biochemical findings in vaginal discharge. Nonspecific vaginitis was also correlated with a history of sexual activity, a history of previous trichomoniasis, current use of nonbarrier contraceptive methods, and, particularly, use of an intrauterine device. G. vaginalis was isolated from 51.3 percent of the total population using a highly selective medium that detected the organism in lower concentration in vaginal discharge than did previously used media. Practical diagnostic criteria for standard clinical use are proposed. Application of such criteria should assist in clinical management of nonspecific vaginitis and in further study of the microbiologic and biochemical correlates and the pathogenesis of this mild but quite prevalent disease.

Adult↗
PubMed1983

Gardnerella vaginalis and anaerobic bacteria in the etiology of bacterial (nonspecific) vaginosis.

G. vaginalis was originally described as the etiologic agent of bacterial vaginosis (nonspecific vaginitis) because it was recovered only from women with signs and symptoms of "bacterial vaginitis" and not from normal controls. Recent data have shown that G. vaginalis is present in normal women but at concentrations lower than the limit of sensitivity of the media formerly used. Detection of low concentrations of G. vaginalis in normal controls has been made possible by development of a selective and differential medium (HBT). Anaerobically performed studies of the vaginal flora have indicated that while lactobacilli predominate in the normal vagina with or without G. vaginalis, anaerobic bacteria including Bacteroides spp., Peptococcus spp., Eubacterium spp. and curved rods as well as G. vaginalis predominate in bacterial vaginosis. Anaerobic bacteria and G. vaginalis are decreased after appropriate therapy. After treatment with metronidazole, lactobacilli again predominate. Lactobacilli are less prevalent after treatment with ampicillin or amoxicillin. These data suggest that as in infections at other mucous membrane sites, bacterial vaginosis is a mixed infection involving a finite number of facultative and anaerobic species. The data also suggest an important role for facultative lactobacilli.

Anti-Bacterial Agents↗
PubMed1982

Biochemical diagnosis of vaginitis: determination of diamines in vaginal fluid.

To assess correlations between the content of the diamines putrescine and cadaverine in vaginal fluid and the clinical manifestations of vaginitis, a rapid procedure for the determination of diamines has been developed. The procedure involves thin-layer chromatography of the dansylated vaginal washings; then the fluorescence of dansyl diamines is compared with that of dansyl alanine. For 520 college women, the result of the test for diamines was positive in 173 (88%) of 197 women with nonspecific vaginitis or vaginitis due to Trichomonas vaginalis and was negative in 291 (90%) of 323 women without nonspecific vaginitis or vaginitis due to T. vaginalis. The diamine content of vaginal fluid specimens after therapy with metronidazole was correlated with the clinical response to treatment.

Cadaverine↗
PubMed1982

Attachment of gonococcal pili to lectin-resistant clones of Chinese hamster ovary cells.

Pili facilitate the attachment of virulent Neisseria gonorrhoeae to host cells. Isolated pili and peptides from pili obtained by cyanogen bromide cleavage were used in attachment assays to Chinese hamster ovary cells and their lectin-resistant clones. Pili and the largest cyanogen bromide fragment (CNBrI) from the amino-terminal portion of the pilin molecule attached to a greater degree to the parent cell and showed 40 to 75% reduced attachment to clones deficient in cell surface oligosaccharides. The CNBrI fragment, with a molecular weight of approximately 10,000, bound specifically to host proteins with subunit molecular weights of 14,000 to 16,000 that were electrophoretically transferred onto nitrocellulose sheets from polyacrylamide gel patterns of host cells. Periodate or galactosidase treatment of pili or the CNBrI fragment markedly reduced attachment, suggesting the importance of galactose residues on pili for their attachment function. Similarly, highly purified exoglycosidase or trypsin treatment of the parent cell reduced attachment, suggesting that oligosaccharide moieties of cell surface components (glycoproteins or glycolipids or both) were receptors for pili attachment. This study indicated that the portion of the pilin molecule involved in attachment resides on the CNBrI fragment and that sugar moieties, both on pili and on the host cell, were required for optimal attachment.

Animals↗
PubMed1982

Serology of Neisseria gonorrhoeae: coagglutination serogroups WI and WII/III correspond to different outer membrane protein I molecules.

The 125I-labeled tryptic peptides of the outer membrane protein I of 33 previously characterized serological reference strains of Neisseria gonorrhoeae were investigated by peptide maps in relation to their coagglutination W serogroup. Serogroup WI strains tended to have lower-molecular-weight protein I molecules than did WII strains, and WIII strains had the highest-molecular-weight protein I molecules, although the serogroup could not be predicted from the molecular weights of the protein I molecules for a given strain. All 13 strains belonging to serogroup WI were found to have 11 peptides in common, as judged by their migration with respect to one another and to the internal marker valine in the peptide maps. Common peptides isolated from a given strain were found to comigrate with the corresponding common peptides from other strains in the same serogroup under various electrophoretic conditions. The 20 strains belonging to serogroups WII and WIII were all found to have 10 common peptides by the same criteria. When common peptides from serogroup WI were compared with the common peptides of serogroups WII and WIII, only three of these peptides appeared to be similar. Thus, two different outer membrane protein I molecules seem to exist which are mutually exclusive. Protein IA molecules contain the antigens recognized as serogroup WI, and protein IB molecules contain the antigens that characterize serogroups WII and WIII.

Agglutination Tests↗
PubMed1982

Detection of a gonococcal endo-beta-N-acetyl-D-glucosaminidase and its peptidoglycan cleavage site.

Neisseria gonorrhoeae contains several hydrolases which may be responsible for gonococcal cell lysis. One of these enzymes, an endo-beta-N-acetyl-D-glucosaminidase, has been extracted from supernatants of sonicated gonococci and partially purified by ammonium sulfate precipitation and affinity and ion-exchange chromatography. This enzyme has a different specificity than egg white lysozyme and cleaves the beta 1 leads to 4 glycosidic linkage between N-acetylglucosamine and N-acetylmuramic acid in gonococcal peptidoglycan.

Acetylglucosaminidase↗
PubMed1982

Rapid method for simultaneous detection of the arginine dihydrolase system and amino acid decarboxylases in microorganisms.

A specific procedure has been developed for the detection of the first two enzymes involved in the arginine dihydrolase system and the detection of the decarboxylases of arginine, glutamic acid, histidine, lysine, ornithine, phenylalanine, tryptophan, and tyrosine. A loopful of growth of each organism from dihydrolase-decarboxylase induction agar medium (or broth) was washed and incubated separately with 0.2-ml samples of three test media supplemented with different amino acids. Each spent test medium was dansylated, and the dansyl derivatives were separated by two-dimensional thin-layer chromatography on polyamide sheets. The end products (citrulline, ornithine, gamma-amino-n-butyric acid, and amines) produced during incubation were estimated by comparing the fluorescent intensities of end products from the spent test media and of the corresponding parent amino acids from test medium controls after thin-layer chromatography. The method is reproducible, requiring incubation of an organism in three test media for 1 h for simultaneous detection of the first two enzymes involved in the arginine dihydrolase system and of eight amino acid decarboxylases. This method has been successfully applied to gram-positive and gram-negative microorganisms and also to Mycoplasmatales. It could simplify and improve the accuracy of the corresponding biochemical tests performed in clinical laboratories for the identification and differentiation of microorganisms, and it may prove particularly useful for the differentiation of species of Pseudomonas and Mycoplasma.

Bacteria↗