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Biomedical subjects

C H Pai

Publications and source records attributed to C H Pai.

At least 19 recordsLinked to original sources
PubMed1992

Prevalence of hepatitis C virus antibody among Korean adults.

To estimate the prevalence of hepatitis C virus (HCV) infection among Korean adults and to present the putative route of HCV transmission among them, serum samples from 4917 adults older than 20 years of age were tested for antibody to HCV (anti-HCV), and histories of blood transfusion and other pertinent information were obtained by self-administered questionnaires. The overall prevalence of anti-HCV was 1.7%; prevalence was 1.4% in subjects with normal levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), 3.3% in those with slightly elevated and 5.9% in those with markedly elevated levels of the enzymes. The prevalence of anti-HCV increased with increasing age (P < 0.01), but was not associated with blood transfusion. The present study suggests that the prevalence of HCV infection was 1.4% and that the major routes of HCV transmission may be other than blood transfusion in healthy Korean adults.

Adult↗
PubMed1991

High-pressure injection injuries of the hand.

The majority of high-pressure injection injuries can produce serious damage to the hand. Nevertheless, the injury may follow a relatively benign course if the injected substance possesses a less harmful nature. Treatment for these injuries requires immediate and aggressive surgery in most circumstances, but conservative treatment may be justified in certain instances. During a 4-year period, eight cases of high-pressure injection injury were encountered. The types of injected material were: four from paint, and one each from grease, water, benzene, and hydraulic oil. Time is an important factor regarding the results, while the types of injected material modify the clinical courses. It is advisable that the etiology of high-pressure injection injury should be established initially, and this factor be taken into consideration in choosing treatment options.

Accidents, Occupational↗
PubMed1990

Carpal bone dislocations: review of 20 cases.

Twenty cases of carpal bone dislocation were encountered during a 7-year period, with an average of 27 months of follow-up. There were 10 types of dislocation in this series, the most common type was transscaphoid perilunate dislocation seen in 9 cases. In addition, there were 2 scaphoid subluxations, 1 volar lunate dislocation, 1 dorsal perilunate dislocation, 1 scaphoid perilunate dislocation, 1 hamate and pisiform dislocation, 1 transhamate pisiform dislocation, 1 trapezoid and 2-5 carpometacarpal joint dislocation, 1 trapezium, trapezoid and 2-4 carpometacarpal joint dislocation, and 2 trapezium periscapholunate dislocations. Methods of treatment included open reduction, closed reduction, proximal row carpectomy, total wrist arthrodesis, and excision of the lunate. In this series, the patterns of dislocation were different for crushing injuries and dorsiflexion injuries. The clinical results associated with the soft tissue injuries of the ipsilateral hand were mostly caused by crushing forces. Although carpal instabilities were noted, there was no significant correlation between the clinical and radiographic results in some of our cases. Best results invariably relied on a stable anatomic reduction and an adequate period of immobilization. Poor results were demonstrated in those cases with incomplete initial reduction, secondary degenerative arthrosis, or nonunion.

Adult↗
PubMed1989

In situ enzyme immunoassay for antiviral susceptibility testing of respiratory syncytial virus.

An enzyme immunoassay (EIA), performed directly on fixed infected monolayers of HEp-2 cells in microtiter plates, was compared with the conventional plaque reduction assay (PRA) method for the determination of antiviral activity of ribavirin against respiratory syncytial virus. A 50% reduction in virus replication was observed at 3.4 and 5.9 mg/L of the drug by EIA and PRA, respectively. EIA is simple to perform and reproducible and has objective end points. Moreover, EIA has advantages over PRA in that results are available sooner and a much wider range of inoculum size can be used without affecting susceptibility data. EIA is suitable for the rapid susceptibility and accurate testing of a large number of clinical isolates.

Antiviral Agents↗
PubMed1989

Risk factors for Escherichia coli O157:H7 infection in an urban community.

Outbreaks of Escherichia coli O157:H7 have been attributed to meat or meat products, particularly ground meat, and to unpasteurized dairy products. However, the risk factors for sporadic cases have not been clearly delineated. Study data were collected by using a self-administered dietary and historical questionnaire on all patients whose history included bloody diarrhea and who attended one of the participating emergency departments. Designation as "case" or "control" occurred after stool culture results were known, eliminating the possibility for recall bias common to this type of study. Cases (E. coli O157:H7-positive) were further matched with one diarrheal and one healthy community control, and more detailed information on food preparation practices and other data were then taken. Of 266 presentations of bloody diarrhea, 103 (38.7%) were due to E. coli O157:H7. Unmatched analyses with bloody diarrheal controls revealed a seemingly lower risk for E. coli O157:H7 infection in fast food restaurant patrons. No increased risk could be detected for ground meat consumption despite adequate study power, although an association between ingestion of undercooked meat and infection (odds ratio = 3.5, P less than .05) was found when community controls were used. Proper food cooking (and handling) rather than the avoidance of particular food products is the preventive measure of choice.

Alberta↗
PubMed1988

Effect of acute Yersinia enterocolitica infection on in vivo and in vitro small intestinal solute and fluid absorption in the rabbit.

The impact of acute Yersinia enterocolitica infection on jejunal and ileal solute and water transport was examined. New Zealand White rabbits (500-600 g) were infected with Y. enterocolitica and compared with unmanipulated controls and pair-fed controls. Transport studies were performed 6 days after infection on jejunum and ileum by an in vivo single-pass perfusion technique and in vitro under short-circuited conditions in Ussing chambers. When studied in vivo, Y. enterocolitica infection resulted in decreased water and electrolyte absorption in the jejunum under basal conditions and in both jejunum and ileum in the presence of glucose. Glucose absorption was also decreased in jejunum and ileum. When studied in vitro, net basal Na+ and Cl- transport was not altered in jejunal or ileal epithelium from infected animals. Glucose-stimulated Na+ absorption was decreased in ileal epithelium, and absorption of 3-O-methyl-D-glucose was decreased in both jejunum and ileum. Secretory capacity of Cl-, as assessed by isobutylmethyl xanthine stimulation, was unimpaired in both jejunum and ileum. Decreased food intake alone, in the pair-fed animals, had little effect on intestinal transport. The results indicate that malabsorption, rather than active intestinal secretion, is the major small intestinal transport defect in acute Y. enterocolitica infection. Furthermore, the abnormalities can be directly attributed to injury induced by the organism itself, rather than malnutrition.

Acute Disease↗
PubMed1988

Colonic function in acute Yersinia enterocolitica infection in rabbits.

The impact of acute Yersinia enterocolitica infection on colonic fluid and electrolyte absorption was studied. New Zealand White rabbits (500-600 g), were infected with Yersinia enterocolitica and compared to unmanipulated controls and pair-fed controls. Water and electrolyte transport were measured in proximal and distal colon by an in vivo single pass perfusion technique and in proximal colon in vitro under short-circuited conditions in Ussing chambers. Infection resulted in severe histologic damage in proximal colon but only mild alterations in distal colon. Pair-fed controls demonstrated decreased absorption in vivo in both proximal and distal colon and Na+ and Cl- secretion in vitro in proximal colon compared to unmanipulated controls. In contrast infection did not alter water and electrolyte absorption in vivo compared to unmanipulated controls despite evidence of net secretion of Na+ and Cl- in vitro. These results indicate that Yersinia enterocolitica infection of the colon does not contribute to fluid and electrolyte losses despite mucosal damage, but rather there appears to be a degree of compensatory colonic salvage.

Animals↗
PubMed1987

The histopathology of rectosigmoid biopsies from adults with bloody diarrhea due to verotoxin-producing Escherichia coli.

The histopathology of rectosigmoid biopsies from 20 patients with bloody diarrhea resulting from verotoxin-producing Escherichia coli infection is reported. The biopsies displayed a range of appearances, from normal to mild, nonspecific inflammation to acute infectious-type colitis. Surface-adherent or invasive bacteria were not identified. The morphologic features of infectious colitis and the absence of bacteria suggest that verotoxin may be responsible for the pathologic changes.

Bacterial Toxins↗
PubMed1987

Invasiveness of Yersinia enterocolitica lacking the virulence plasmid: an in-vivo study.

Rabbits were given, by the intra-gastric route, two isogenic strains of Yersinia enterocolitica that differed only in the presence or absence of the virulence plasmid. Clinical illness and characteristic morphological lesions of Y. enterocolitica infection were seen only in rabbits infected with the plasmid-bearing strain (MCH700S). Although rabbits infected with a strain lacking the plasmid (MCH700L) remained healthy, mild histological changes in the small intestine, consisting of epithelial-cell damage, dilatation of lymphatics and a slight increase in neutrophil polymorphonuclear leukocytes in lamina propria, were seen in the first 12 h after inoculation. Bacteria, which were identified as Y. enterocolitica by indirect fluorescent antibody staining, were seen in dilated lymphatics. These early lesions tended to abate quickly and were no longer detectable at 24 h. Strain MCH700L was recovered from the mesenteric lymph nodes in increasing numbers until 24 h after inoculation; the number then began to decrease rapidly. In contrast, the early lesions in rabbits given strain MCH700S progressed to micro-abscesses, focal destruction of villi, and ulcerations beginning 24 h after inoculation; the number of bacteria recovered from the lymph nodes continued to increase beyond 24 h after inoculation. Bacteria were also recovered from the liver and spleen. These results suggest that both plasmid-bearing and non-bearing strains of Y. enterocolitica are capable of penetrating the intestinal mucosa. However, the virulence plasmid is required for invading bacteria to proliferate in the host tissue and to establish infection.

Animals↗
PubMed1987

Plasmid-mediated resistance to phagocytosis in Yersinia enterocolitica.

Results of our previous studies have shown that the chemiluminescence response of human neutrophils (polymorphonuclear leukocytes [PMNs]) is inhibited by plasmid-mediated cell surface components from Yersinia enterocolitica. In this study we examined the susceptibility to phagocytosis of Y. enterocolitica cells with or without plasmid-mediated surface structure and the effect of isolated outer membrane fragments on phagocytosis of Escherichia coli by PMNs in vitro. Y. enterocolitica cells with expressed plasmid-mediated surface structure were much less sensitive to ingestion by PMNs than those without it, and the resistance to phagocytosis was readily eliminated in a dose-dependent fashion by pronase treatment of whole cells, which was shown to remove plasmid-encoded outer membrane proteins. Ingestion and intracellular killing of E. coli were inhibited significantly in the presence of isolated outer membrane fragments derived from plasmid-bearing Y. enterocolitica cells. To assess the interaction of Y. enterocolitica with phagocytic cells in vivo, two isogenic strains of Y. enterocolitica, differing only in the presence or absence of the virulence plasmid, were inoculated intradermally into the backs of rabbits; and tissue sections obtained at 12 h postinoculation were examined by light and electron microscopy. The plasmidless strain was found almost entirely in PMNs or mononuclear cells. In contrast, the plasmid-bearing strain was found to be surrounded by, or interspersed with, PMNs and mononuclear cells; but most bacteria were extracellular, with little evidence of phagocytosis. These results suggest that plasmid-mediated cell surface components of Y. enterocolitica act as antiphagocytic factors, thus facilitating the survival and proliferation of the organism in the host tissue.

Animals↗
PubMed1987

Selective and differential medium for recovery of Pseudomonas cepacia from the respiratory tracts of patients with cystic fibrosis.

A selective and differential medium, OFPBL (oxidation-fermentation base supplemented with agar, lactose, and two antimicrobial agents), for the isolation of Pseudomonas cepacia from respiratory specimens of patients with cystic fibrosis was developed and tested. Among 725 specimens submitted from seven centers over a 4- to 6-month period, 58 (8%) yielded P. cepacia on OFPBL; only 19 of these were recovered on MacConkey or sheep blood agar (P less than 0.001). No isolate was recovered on MacConkey or sheep blood agar alone. Ranges of recovery rates among centers were 0 to 15% on OFPBL and 0 to 10% on MacConkey or sheep blood agar. Ninety percent of P. cepacia isolates were detected on OFPBL in less than or equal to 3 days. Other nonfermenters and yeasts isolated on OFPBL were distinguished from P. cepacia by failure to acidify the medium. The new medium was clearly superior to MacConkey and sheep blood agars for the isolation of P. cepacia from the respiratory secretions of patients with cystic fibrosis.

Culture Media↗
PubMed1986

Sepsis and cholestasis: the in vitro effects of bacterial products on 14C-taurocholate uptake by isolated rat hepatocytes.

Bacterial endotoxins are known to be an important cause of cholestasis, yet not all organisms that cause cholestasis produce endotoxins. In order to determine whether bacterial products other than endotoxins may be involved in the cholestasis process, 14C-taurocholate (TC) uptake by isolated rat hepatocytes was measured in the presence of mid-log, stationary and mid-death phase bacterial broth supernatants from eight common bacterial pathogens. The results were then correlated with a quantitative assessment of endotoxin production by each organism. Supernatants from Haemophilus influenzae, Pseudomonas aeruginosa and Klebsiella pneumonia demonstrated a striking inhibitory effect on bile salt uptake (77.2 +/- 6.7, 46.9 +/- 6.5 and 32.9 +/- 7.1% maximum inhibition of 14C-TC uptake, respectively) when compared to sterile broth controls. Streptococcus faecalis (Enterococcus), Escherichia coli, Staphylococcus aureus and Bacteroides fragilis products, on the other hand, had relatively minor effects (12.3 +/- 5.2, 12.0 +/- 7.5, 8.4 +/- 6.7 and less than 5.0% inhibition respectively), while those from Proteus mirabilis had an intermediate effect (18.5 +/- 8.3% inhibition). Bile salt efflux rates (16.0 +/- 2.7 and 25.1 +/- 4.2 nmol/min/10(6) hepatocytes, mean +/- SEM) were similar in bacteria demonstrating marked uptake inhibition (Haemophilus influenzae, Pseudomonas aeruginosa) when compared to those with only minor inhibitory effects (Staphylococcus aureus, Bacteroides fragilis) (14.3 +/- 1.1 and 18.4 +/- 2.6 nmol/min/10(6) hepatocytes, respectively, p greater than 0.05). 14C-TC uptake inhibition did not correlate with the amount of endotoxin produced by each organism (r = 0.251). The results of this study indicate that bacteria produce a factor other than endotoxin that significantly inhibits bile salt uptake by isolated rat hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Experimental infection of infant rabbits with verotoxin-producing Escherichia coli.

To study the pathogenesis of diarrheal disease due to verotoxin (VT)-producing Escherichia coli, 3-day-old rabbits were inoculated intragastrically with live E. coli O157:H7 (high VT producer), E. coli O113:K75:H21 (low VT producer), or O157:H45 (VT negative) and were examined for clinical symptoms, bacterial colonization, presence of detectable free VT in the intestines, and histological changes. Diarrhea developed consistently with 10(8) bacteria of E. coli O157:H7 but was observed only infrequently with even a higher dose of E. coli O113:K75:H21. VT-negative strains failed to cause diarrhea under the same experimental conditions. E. coli O157:H7 was recovered from the colon of infected animals in a significantly higher concentration than from the small intestine, and the clinical symptoms correlated with the presence of detectable free VT in the colon. Histological changes were seen mainly in the mid- and distal colon; these changes were characterized by a vast increase in apoptosis in the surface epithelium, increased mitotic activity in the crypts, mucin depletion, and a mild to moderate infiltration of neutrophils in the lamina propria and epithelium. Multiple foci of attached bacteria were seen on the surface epithelium of the gut-associated lymphoid tissue, cecum, and colon. Bacteria were never seen in epithelial cells or the lamina propria. These mucosal abnormalities as well as clinical symptoms were reproduced in infant rabbits by the intragastric administration of VT alone. These results are consistent with the hypothesis that VT plays a major role in the pathogenesis of diarrhea caused by E. coli O157:H7 and other VT-producing E. coli.

Age Factors↗
PubMed1985

Inhibition of human neutrophil chemiluminescence by plasmid-mediated outer membrane proteins of Yersinia enterocolitica.

Recent studies have shown that the cell surface properties of Yersinia enterocolitica are altered by the presence of the virulence plasmid, which mediates temperature-inducible outer membrane proteins (OMP). We investigated the interaction of Y. enterocolitica with human polymorphonuclear leukocytes by monitoring luminol-enhanced chemiluminescence (CL) responses. A plasmid-bearing strain grown at 37 degrees C induced four- to sixfold less CL than did the same strain grown at 25 degrees C or a plasmidless, isogenic strain grown at either temperature. Inhibition of CL responses by whole cells was related to plasmid-mediated expression of OMP. The OMP alone could inhibit the CL response of polymorphonuclear leukocytes stimulated by either opsonized zymosan or whole cells of Y. enterocolitica. Pronase treatment of whole cells, which removed the plasmid-mediated OMP, resulted in partial but significant elimination of CL inhibition by whole cells and by OMP derived from them. Incubation with Y. enterocolitica for 60 min did not affect the viability of polymorphonuclear leukocytes. Our results suggest that the interaction of Y. enterocolitica with human polymorphonuclear leukocytes is directly affected by the plasmid-mediated OMP.

Bacterial Outer Membrane Proteins↗