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Biomedical subjects

K H Choi

Publications and source records attributed to K H Choi.

At least 127 records · Page 7Linked to original sources
PubMed1996

Factors affecting low values of serum albumin in CAPD patients.

To investigate the factors affecting low values of serum albumin (SA) in continuous ambulatory peritoneal dialysis (CAPD) patients, we undertook a cross-sectional study of 106 CAPD patients, with a mean age of 49.0 years and dialysis duration of 43.4 months, with respect to demographic, clinical, and biochemical parameters. In group I (n = 28, SA < or = 3.5 g/dL), diabetics were more common, patients were significantly older, and more patients were malnourished, according to the subjective global assessment (SGA), compared to group II (n = 78, SA > 3.5 g/dL). Serum C-reactive protein (CRP), lipoprotein (a), and 24-hour dialysate-to-plasma creatinine concentration ratio (D/P) were significantly higher, and 24-hour dialysate albumin was greater in group I. Compared to group II, group I had significantly lower serum creatinine and urea nitrogen appearance (UNA). Blood urea nitrogen (BUN), lean body mass (LBM), % of body weight (%BW), and normalized protein equivalent of nitrogen appearance (nPNA) tended to be lower in the low SA group, without statistical significance. There were no differences in the duration of CAPD, peritonitis rate, serum insulin-like growth factor-I (IGF-I), anthropometric data, dietary assessment, dialysis adequacy, and residual renal function (RRF) between the two groups. SA was positively correlated with serum creatinine, IGF-I, LBM, UNA, BUN, nPNA, and CAPD duration, and was negatively correlated with 24-hour D/P, 24-hour dialysate albumin, age, CRP, and bicarbonate (HCO3-). By stepwise multiple logistic regression analysis, 24-hour D/P, age, CRP, and SGA were independent risk factors for low SA level. In conclusion, SA seems to be influenced not only by nutritional factors but also by nonnutritional factors such as peritoneal membrane transport characteristics, age, and presence of acute phase protein response manifested by CRP elevation.

Adult↗
PubMed1996

Cognitive and emotional assessments of perceived risk for HIV among unmarried heterosexuals.

We examined perceived risk of contracting HIV using assessments of likelihood and worry in a probability sample of unmarried heterosexuals. Perceptions of the likelihood of contracting HIV and worry about HIV were only modestly correlated (r = .23), suggesting that they are different constructs. Far more respondents expressed worry (43%) than expressed the belief that they were at risk for HIV (9%). A significant proportion of the sample reported experiences that may have placed them at risk for HIV transmission. Demographic and psychosocial correlates of perceived likelihood and worry were examined in separate multivariate logistic analyses. Misconceptions about HIV transmission, a history of injection-drug-using sexual partners, and less education were associated with higher perceived likelihood of contracting HIV. Misconceptions, having multiple sexual partners in the past year, and a history of sexually transmitted diseases (STDs) were associated with high worry about HIV. Implications of the findings for correcting HIV-related misconceptions are discussed.

Adult↗
PubMed1995

Colorimetric assay using XTT for assessing virulence of avian Pasteurella multocida strains.

A colorimetric assay using sodium 3,3'-[1[(phenylamino)carbonyl]3,4- tetrazolium]-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate (XTT) was adapted to quantitate bactericidal activity of chicken macrophage HD 11 cell line against five Pasteurella multocida strains and an avirulent transposon insertion mutant. The strains used were virulent P1059, and D92, and four avirulent strains including a streptomycin resistant mutant of P1059 (P1059 SmR), two live vaccine strains namely, the Clemson University (CU) and M9, and a transposon insertion mutant PmTn-294. Percentage of bacteria killed by chicken macrophage (HD 11) cells was determined by extrapolation from a standard formazan curve derived by incubating XTT with known bacterial cell numbers of each strain. The amount of formazan as measured by absorption at 450 nm was directly related to the number of viable bacterial cells. The percentages of P1059 SmR, CU, M9 and PmTn-294 killed by HD 11 cells were approximately 50%, 61%, 25% and 34%, respectively. By contrast, the virulent P1059 and D92 strains were resistant to killing, and were able to replicate inside the HD 11 cells. Association of virulence with resistance to phagocytic killing by HD 11 cells as assessed by the colorimetric bactericidal assay, was validated with resistance to complement (C')-mediated killing and a turkey mortality test. Strains P1059 and D92 were resistant to C'-mediated killing, whereas strains P1059 SmR, CU, M9 and PmTn-294 strains were susceptible. All turkeys challenged with P1059 or D92 were dead within 18 hrs. Mortality did not occur in turkeys challenged with strains of P1059 SmR, M9 and PmTn-294. The mortality among CU challenged turkeys ranged from 0 to 40%. The results suggest that the colorimetric bactericidal assay using XTT can be used to quantitate chicken macrophage phagocytic killing of P. multocida strains, and may be a valuable assay to differentiate virulent from avirulent strains of avian P. multocida.

Animals↗
PubMed1995

Neuronal dysfunction in patients with closed head injury evaluated by in vivo 1H magnetic resonance spectroscopy.

RATIONALE AND OBJECTIVES: With the use of localized, water-suppressed in vivo 1H magnetic resonance spectroscopy (MRS), the proton metabolic alterations of white matter in patients with closed head injury (CHI) and healthy controls are evaluated, and metabolic alterations with Glasgow Outcome Scale (GOS) scores are compared. METHODS: Patients with CHI (n = 10) and healthy control subjects (n = 10) underwent MRS examinations using a stimulated-echo acquisition mode pulse sequence that provided 2 x 2 x 2 cm3 volume of interest in the left frontoparietal white matter. Proton metabolite ratios relative to creatine were obtained using a Marquart algorithm. RESULTS: The specific feature in patients with CHI was significant decrease of N-acetylaspartate (NAA)/creatine ratio compared with normal controls. No clear correlation of other metabolite ratios such as choline/creatine and inositols creatine was established. The level of NAA/creatine ratio was significantly correlated with GOS. CONCLUSIONS: Results of this preliminary study suggest that the reduction of NAA/creatine ratio may indicate neuronal loss in patients with CHI. The NAA/creatine ratio may serve as a metabolic criterion to predict the GOS of patients with CHI. Thus, in vivo 1H MRS may be a useful modality in the clinical evaluation of patients with CHI based on the proton metabolite concentrations of cerebral white matter.

Algorithms↗
PubMed1995

Hypoxia induces changes in phospholipase A2 in rat proximal tubules: evidence for multiple forms.

Increased free fatty release during hypoxia is believed to contribute to cell injury. This phenomenon is likely to be mediated through activation of specific isoforms of phospholipase A2 (PLA2). In this study, PLA2 enzymatic activity was measured in cell-free extracts prepared from rat renal proximal tubules. Both soluble and membrane-associated PLA2 activity were detected. All PLA2 activity detected during normoxia was Ca2+ dependent. Fractionation of cytosolic extracts by gel filtration revealed three peaks of PLA2 activity. Exposure of tubules to hypoxia resulted in stable activation of soluble PLA2 activity, which correlated with disappearance of the highest molecular mass form (> 100 kDa) and appearance of a low-molecular-mass form (approximately 15 kDa) of PLA2. Hypoxia also resulted in release of a low-molecular-mass form of PLA2 into the extracellular medium. Pretreatment of tubules with glycine before hypoxia blocked this release of PLA2 but not activation of soluble PLA2 activity. These studies provide direct evidence for PLA2 activation during hypoxia and suggest that multiple mechanisms regulate free fatty acid release associated with hypoxia injury.

Animals↗
PubMed1995

Risk factors for HIV and other sexually transmitted diseases and prevention practices among US heterosexual adults: changes from 1990 to 1992.

OBJECTIVES: The National AIDS Behavioral Survey (1990-1992) of heterosexual adults (18-49 years) measured human immunodeficiency virus (HIV) risk factors, condom use, and HIV antibody testing, with a focus on major "high-risk" cities. METHODS: A longitudinal survey was conducted. RESULTS: There was little reduction in the overall prevalence of HIV risk factors in the national or high-risk cities cohorts over time. Despite this picture of stability, approximately 39% of the population at risk for HIV because of multiple sexual partners turns over annually. There was little change in HIV test-seeking or in consistent condom use with primary sexual partners. Although the majority of at-risk respondents used condoms sporadically or not at all (65%), a significant increase in condom use was found among those reporting multiple sexual partners in both waves, particularly among Black heterosexuals. Data from other surveys and condom sales nationally support the findings. CONCLUSIONS: There is a need for a series of surveys in this area to assess the reliability of the present findings and to monitor the general US population's response to prevention programs.

Adolescent↗
PubMed1995

Prognostic factors and renal survival rates in IgA nephropathy.

A retrospective study of 223 patients with IgA nephropathy (IgAN) was performed to clarify the prognostic factors and the renal survival rates of the disease. One hundred twenty-two patients were followed-up for more than 6 months after their renal biopsy (mean follow-up duration: 43.0 months), and 20 of them (16.4%) had progressed to end-stage renal disease (ESRD). Using univariate analysis, 8 risk factors (2 clinical and 6 histopathological findings) for developing ESRD were identified: renal insufficiency at initial presentation (serum creatinine > or = 1.5 mg/dl); heavy proteinuria (> or = 3.5 gm/day); moderate to severe histopathologic findings such as class IV/V lesions by W.H.O. classification, mesangial hypercellularity, glomerular sclerosis, interstitial infiltration, interstitial fibrosis, and tubular atrophy. In multivariate regression analysis, class IV/V lesions and renal insufficiency at initial presentation were the independent prognostic factors of IgAN. The renal survival rates were 100% at 1 year, 97.0% at 3 years, and 78.9% at 5 years. In conclusion, it seems that about 20% of IgAN patients have a risk to progress to ESRD within 5 years, and a careful follow-up is recommended especially in patients who have either renal insufficiency at the time of presentation or severe renal pathology (class IV/V lesions).

Adolescent↗
PubMed1995

The effect of lovastatin on proliferation of cultured rat mesangial and aortic smooth muscle cells.

In order to investigate the anti-proliferative effect of 3-hydroxy-3-methylglutaryl coenzyme. A reductase inhibitor, we evaluated the effects of lovastatin on DNA replication and the proliferation of rat mesangial and aortic smooth muscle cells, both of which were mesenchymal origin cells. Proliferations were determined by measuring [3H]thymidine uptake, and counting the number of cells. Growth-arrested mesangial and aortic smooth muscle cells were exposed to platelet-derived growth factor (PDGF), endothelin (ET) and angiotensin II (Ang II) to stimulate mitogenesis. All agents exhibited dose-dependent stimulation of [3H] thymidine uptake. PDGF was more potent than the others. Ang II increased [3H] thymidine uptake without demonstrable mitogenic activity. Lovastatin inhibited PDGF (10 ng/ml in mesangial cell, 25 ng/ml in smooth muscle cell)-, ET (10(-7)M)- and Ang II (10(-7)M)-induced [3H] thymidine uptake significantly in a dose-dependent manner in both cells. The increase of cell number in response to PDGF and ET treatment were also inhibited at 10 microM of lovastatin. The inhibitory effect of lovastatin was largely overcome in the presence of exogenous mevalonate at 200 microM, with 75.5% restoration from lovastatin-induced inhibition on PDGF-induced [3H] thymidine uptake in mesangial cells (77.8% in aortic smooth muscle cells). However, the addition of cholesterol did not prevent inhibition by lovastatin. In conclusion, lovastatin had an inhibitory effect on mesangial and aortic smooth muscle cell proliferation, and mevalonate was essential for DNA replication in both types of cells. Lovastatin may reduce glomerular and atherosclerotic injury through an anti-proliferative effect on mesangial and vascular smooth muscle cells, in addition to lowering circulating lipids.

Angiotensin II↗
PubMed1995

Female partners of AIDS patients in Uganda: reported knowledge, perceptions and plans.

OBJECTIVE: To assess reported knowledge of a partner's AIDS diagnosis, perceived risk of HIV infection, need for HIV testing and future support plans among women partners of male Ugandan AIDS patients. SUBJECTS AND METHODS: A cross-sectional descriptive survey was conducted at New Mulago Hospital, Kampala, Uganda. The subjects were women partners of consecutive male AIDS patients admitted to medical wards. RESULTS: Only 12% reported their partner's AIDS diagnosis; women who reported knowing were less likely to be financially dependent on the partner. Most women (76%) reported being at risk of HIV; in general, these women were older, in a newer relationship, had less children and were in customary rather than civil or cohabiting marriages. More than half (56%) of the women reported a need for HIV testing, though few (5%) had been tested. Those who stated the need for HIV testing were in a newer relationship, had less children and were more financially independent of their husbands; women in a cohabiting type marriage were less likely to report their need for testing than those in a civil or customary marriage. About half (56%) reported plans for future support if their husbands did not recover; these women were more likely to be in an older relationship and to have more children. CONCLUSIONS: Most women partners of AIDS patients in New Mulago Hospital reported no knowledge of their husbands' diagnosis. Over half perceived a need to be tested but very few reported having been tested, and only half reported having planned for the future of their families. Interventions are urgently needed to address barriers to knowledge and to acknowledgement of a partner's AIDS diagnosis, to HIV testing and to planning for the future.

AIDS Serodiagnosis↗
PubMed1994

Formation of a hairpin structure by telomere 3' overhang.

The telomeres of most eukaryotes contain tandemly-repeated DNA sequences, with a cluster of G residues on one strand. Recent studies showed that the Oxytricha telomeric DNA oligonucleotide, d(G4T4G4), dimerizes to form a quadruplex in the presence of Na+ or K+. We have observed that the oligonucleotide d(G4T4G4) does not dimerize in the presence of Li+ ion at low sample concentrations. In the monomeric state, this molecule forms a simple foldback hairpin structure containing G x G reverse Hoogsteen basepairs in the stem region. This hairpin structure has a thermal stability which is well reconciled with telomere functions in vivo.

Animals↗
PubMed1994

Posterior lumbar apophyseal ring fractures: a report of 20 cases.

Posterior apophyseal ring fracture (PARF) of the lumbar spine is an uncommon injury thought usually to occur in adolescence. We analysed CT findings in 20 cases (19 patients), whose age ranged from 16 to 45 years (average 30 years). The PARF could be divided into two distinct groups on the basis of the shape and location of the fracture and the defect of the vertebral rim. In group 1 (2 cases), PARF involved the central aspect of the inferior vertebral rim and bone fragments were large and broad-based. In group 2, PARF were located at the posterolateral margin of the superior vertebral rim and bone fragments were small and focal. The great majority of previously reported cases belonged to our group 1. A pathogenesis for each group is suggested.

Adolescent↗
PubMed1994

Spontaneous evolution of posttraumatic subdural hygroma into chronic subdural haematoma.

Thirteen of 145 patients with post-traumatic subdural hygroma (SDHy) developed chronic subdural haematoma (CSDH) at the involved site over a period of 6 years. CSDHs were found at the site of SDHys with no history of further head injury at a mean interval of 56 days. It appeared that these 13 patients did not have any distinguishing clinical features early on. Old age and brain atrophy on CT scans do not seem to be reasonable causative factors in the evolution of SDHy into CSDH. Initial enlargement of subdural accumulations at an early stage of SDHy and a subsequent increase in density at a later stage may point to the development of CSDH from SDHy in some instances. Ten of these 13 CSDH cases underwent surgical drainage, and the remaining 3 cases received no specific management. All resolved completely. The prognosis was good in all patients. The possible mechanism for the evolution of SDHy into CSDH is discussed.

Adult↗
PubMed1994

Injecting drug use and HIV infection in southwest China.

OBJECTIVES: To determine the prevalence of drug injection among drug users, the seroprevalence of HIV and risk factors for HIV infection among injecting drug users (IDU), and to determine heterosexual transmission of HIV among IDU and their spouses in southwest China. METHODS: Using a cross-sectional design, we conducted an HIV seroprevalence and behavioral survey in three rural counties of Yunnan province, Ruili, Longchuan and Luxi in southwest China, bordering Myanmar (Burma). A total of 860 drug users were recruited in randomly selected communities at the three study sites (response rate, 97%). In addition, a random sample of 62 wives of HIV-infected IDU were assembled from 460 known HIV-positive IDU in Ruili and Longchuan (response rate, 81%). RESULTS: In the sample of 860 drug users, 33% reported injecting drugs. Among the 282 subjects who injected drugs, 82% began intravenous drug use after 1988; 64% injected drugs at least once every day. All subjects shared needles but none cleaned the injection equipment with alcohol or bleach. Overall, 49% tested HIV-positive. HIV seropositivity was independently correlated with a longer history of drug injecting, daily injecting, frequent needle-sharing, being younger, and living in Ruili county. Among the 62 wives of HIV-positive IDU, none used condoms during sex and 10% tested HIV-positive. CONCLUSIONS: We conclude that the introduction of HIV into drug-using communities and the rapid increase in heroin injecting in this population appear to have triggered an explosive HIV epidemic among IDU in southwest China. We recommend that AIDS prevention efforts should begin immediately and focus on discouraging the shift from opium smoking to heroin injecting, needle-sharing, and unprotected sex among drug users and their partners.

Adult↗