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Biomedical subjects

A Kim

Publications and source records attributed to A Kim.

At least 73 records · Page 4Linked to original sources
PubMed1999

Recovery following relief of unilateral ureteral obstruction in the neonatal rat.

BACKGROUND: Obstructive nephropathy is a primary cause of renal insufficiency in infants and children. This study was designed to distinguish the reversible and irreversible cellular consequences of temporary unilateral ureteral obstruction (UUO) on the developing kidney. METHODS: Rats were subjected to UUO or sham operation in the first 48 hours of life, and the obstruction was removed five days later (or was left in place). Kidneys were removed for study 14 or 28 days later. In additional groups, kidneys were removed at the end of five days of obstruction. Immunoreactive distribution of renin was determined in arterioles, and the distribution of epidermal growth factor, transforming growth factor-beta1, clusterin, vimentin, and alpha-smooth muscle actin was determined in tubules and/or interstitium. The number of glomeruli, glomerular maturation, tubular atrophy, and interstitial collagen deposition was determined by morphometry. Renal cellular proliferation and apoptosis were measured by proliferating cell nuclear antigen and the TdT uridine-nick-end-label technique, respectively. The glomerular filtration rate was measured by inulin clearance. RESULTS: Renal microvascular renin maintained a fetal distribution with persistent UUO; this was partially reversed by the relief of obstruction. Although glomerular maturation was also delayed and glomerular volume was reduced by UUO, the relief of obstruction prevented the reduction in glomerular volume. Although relief of obstruction did not reverse a 40% reduction in the number of nephrons, the glomerular filtration rate of the postobstructed kidney was normal. The relief of obstruction did not improve tubular cell proliferation and only partially reduced apoptosis induced by UUO. This was associated with a persistent reduction in the tubular epidermal growth factor. In addition, the relief of obstruction reduced but did not normalize tubular expression of transforming growth factor-beta1, clusterin, and vimentin, all of which are evidence of persistent tubular injury. The relief of obstruction significantly reduced interstitial fibrosis and expression of alpha-smooth muscle actin by interstitial fibroblasts, but not to normal levels. CONCLUSIONS: The relief of obstruction in the neonatal rat attenuates, but does not reverse, renal vascular, glomerular, tubular, and interstitial injury resulting from five days of UUO. Hyperfiltration by remaining nephrons and residual tubulointerstitial injury in the postobstructed kidney are likely to lead to deterioration of renal function later in life.

Actins↗
PubMed1999

Human corneal epithelial cell adhesion to laminins.

PURPOSE: To analyze alpha-integrin mediated adhesion of human corneal epithelial cells to placental and EHS laminin isoforms. METHODS: Western blot analysis was used to partially characterize commercially available preparations of laminin isolated from the mouse EHS sarcoma and from human placenta. Using the human corneal epithelial cell line HCE-T, adhesion to laminin isoforms and fibronectin was determined using a colorimetric adhesion assay. alpha-integrin sub-unit modulation of corneal epithelial cell interaction with laminin isoforms was analyzed using immunofluorescence microscopy and adhesion assays incorporating functional blocking antibodies. RESULTS: In short-term adhesion assays, the preferred substrate for HCE-T attachment is placental laminin. Immunofluorescence microscopy reveals that alpha-integrin protein localization patterns are not significantly different in HCE-T interacting with EHS or placental laminin. However, in short-term assays alpha3 integrin plays a major role, and alpha2 integrin a minor role, in mediating HCE-T adhesion to laminin. alpha6 integrin does not appear to mediate adhesion to either substrate. CONCLUSIONS: These studies demonstrate that human corneal epithelial cells are capable of rapid adhesion to, and enhanced spreading on, laminin isoforms not characteristically resident in the adult corneal basement membrane. This characteristic of human corneal epithelium may explain, at least in part, why amniotic membrane transplantation is proving to be clinically useful for human ocular surface reconstruction.

Animals↗
PubMed1999

Which clinical anesthesia outcomes are important to avoid? The perspective of patients.

UNLABELLED: Healthcare quality can be improved by eliciting patient preferences and customizing care to meet the needs of the patient. The goal of this study was to quantify patients' preferences for postoperative anesthesia outcomes. One hundred one patients in the preoperative clinic completed a written survey. Patients were asked to rank (order) 10 possible postoperative outcomes from their most undesirable to their least undesirable outcome. Each outcome was described in simple language. Patients were also asked to distribute $100 among the 10 outcomes, proportionally more money being allocated to the more undesirable outcomes. The dollar allocations were used to determine the relative value of each outcome. Rankings and relative value scores correlated closely (r2 = 0.69). Patients rated from most undesirable to least undesirable (in order): vomiting, gagging on the tracheal tube, incisional pain, nausea, recall without pain, residual weakness, shivering, sore throat, and somnolence (F-test < 0.01). IMPLICATIONS: Although there is variability in how patients rated postoperative outcomes, avoiding nausea/vomiting, incisional pain, and gagging on the endotracheal tube was a high priority for most patients. Whether clinicians can improve the quality of anesthesia by designing anesthesia regimens that most closely meet each individual patient's preferences for clinical outcomes deserves further study.

Adult↗
PubMed1999

Expression of p53 protein in rheumatoid arthritis synovium. An immunohistochemical analysis.

OBJECTIVES: Mutation of p53 may play a role in manifestation of rheumatoid arthritis synovium, but several studies on p53 expression in synovial tissues of rheumatoid arthritis showed conflicting results. We investigated the amount and pattern of p53 positive cells in rheumatoid arthritis synovium, in comparison with osteoarthritis synovium, by using immunohistochemistry with two other monoclonal antibodies for p53. METHODS: Synovial tissues from 9 patients with rheumatoid arthritis and 5 patients with osteoarthritis were examined for p53 expression by immunohistochemistry with 2 monoclonal antibodies for p53, DO-1 and DO-7. Histologic features of inflammation were also scored and compared with p53 expression. RESULTS: There was no significant difference between inflammatory scores in both groups. In the synovial tissues of rheumatoid arthritis patients, p53 positive cells were detected in 3 out of 9 samples(33%) and p53 expressions were restricted to inflammatory mononuclear cells, but synovial lining cells, subsynovial fibroblast-like cells and vascular endothelial cells were p53 negative. p53 expressions in osteoarthritis synovial tissues as control were observed in 2 out of 5 samples(40%) and the amount and pattern of p53 positive cells were comparable to those seen in rheumatoid arthritis synovial tissues. There was no demonstrable correlation between the synovial tissues of both groups with respect to inflammation scores and expression of p53 protein. CONCLUSION: Our findings suggest that altered p53 expression may not play a significant role in the manifestation of rheumatoid arthritis synovium. However these data need to be strengthened by increasing the number of samples and molecular biology approaches.

Arthritis, Rheumatoid↗
PubMed1999

Unilateral ureteral obstruction in early development alters renal growth: dependence on the duration of obstruction.

PURPOSE: Over 90% of nephrogenesis in the rat takes place postnatally in the first 10 days, analogous to the midtrimester human fetus. We wished to determine the relationship between the duration of unilateral ureteral obstruction and growth and morphology of both kidneys following relief of the obstruction in the neonatal rat. MATERIALS AND METHODS: One ureter of 1 day-old rats was sham-operated or occluded and released 1, 2, 3, or 5 days later, or not released. Fourteen or 28 days later, renal mass, tubular atrophy, and interstitial fibrosis were determined in the obstructed and contralateral kidney of each group. RESULTS: At 28 days, there was a linear relationship between kidney/body weight ratio and duration of obstruction, such that the decrement in renal mass resulting from ipsilateral obstruction was precisely compensated by an equal increment in the mass of the contralateral kidney (both, p <0.0001). Tubular atrophy was increased 100-fold in kidneys of rats with 28 days continuous ipsilateral obstruction, while relief of obstruction after 2 to 5 days reduced tubular atrophy by 90% (p <0.01). Interstitial fibrosis was also markedly reduced by relief of obstruction, with the severity of fibrosis being proportional to the duration of obstruction. CONCLUSIONS: We conclude that ureteral obstruction during the critical period of nephrogenesis impairs growth of the obstructed kidney and stimulates growth of the contralateral kidney in direct proportion to the duration of obstruction. Moreover, counterbalance between the two kidneys is finely regulated. Even 2 days of ureteral obstruction (with subsequent relief) induces contralateral renal growth, and induces ipsilateral tubular atrophy. However, the time dependence of renal injury on duration of obstruction suggests that earlier relief of obstruction in the developing kidney may allow greater ultimate preservation of functional renal mass.

Age Factors↗
PubMed1999

Current trends in cervical ripening and labor induction.

Labor is induced in more than 13 percent of deliveries in the United States. Postdate pregnancy is the most common indication. Oxytocin is the drug of choice for labor induction when the cervical examination shows that the cervix is favorable. The use of this agent requires experience and vigilant observation for uterine hyperstimulation, hypertonus or maternal fluid overload. In a patient whose cervix is unfavorable, the use of prostaglandin analogs for cervical ripening markedly enhances the success of inductions. Misoprostol, a prostaglandin E1 analog marketed as a gastrointestinal mucosal protective agent, is safe, efficacious and inexpensive for use in cervical ripening and labor induction. Further studies will better delineate its optimal use. Family physicians need to be familiar with the various methods of cervical ripening and labor induction.

Cervical Ripening↗
PubMed1999

Formation and repair of DNA adducts in vinyl chloride- and vinyl fluoride-induced carcinogenesis.

Vinyl chloride is a known human and animal carcinogen that induces angiosarcomas of the liver. We review here studies on the formation and repair of DNA adducts associated with vinyl chloride and vinyl fluoride in exposed and control rodents and unexposed humans. These vinyl halides induce etheno (epsilon) adducts that are identical to those formed after lipid peroxidation. Of these adducts, N2,3-ethenoguanine (epsilon G) is present in greatest amounts in tissues of exposed animals. After exposure to vinyl chloride for four weeks, epsilon G levels attain steady-state concentrations, such that the amount of newly formed adducts equals the number of adducts that are lost each day. We report the first dosimetry of epsilon G in rats exposed to 0, 10, 100 or 1100 ppm vinyl chloride for five days or four weeks. The number of adducts increased in a supralinear manner. Exposure to 10 ppm vinyl chloride for five days caused a two- to threefold increase in epsilon G over that of the controls, while four weeks' exposure resulted in a fivefold increase. This was confirmed with [13C2]vinyl chloride and by measuring exogenous and endogenous adducts in the same animals. Exposure to 100 ppm vinyl chloride for four weeks caused a 25-fold increase in epsilon G levels over that found in control rats, while exposure to 1100 ppm resulted in a 42-fold increase. The amount of endogenous epsilon G was similar in liver DNA from rats and humans. A comparable response to exposure was seen in rats and mice exposed to 0, 25, 250 or 2500 ppm vinyl fluoride for 12 months. There was a very high correlation between epsilon G levels in rat and mouse liver at 12 months and the incidence of haemangiosarcoma at two years. We were able to demonstrate that the target cell population for angiosarcoma, the nonparenchymal cells, contained more epsilon G than hepatocytes, even though nonparenchymal cells are exposed by diffusion of vinyl halide metabolites formed in hepatocytes. The expression of N-methylpurine-DNA glycosylase mRNA was induced in rat liver after exposure to either 25 or 2500 ppm vinyl fluoride. When this induction was investigated in hepatocytes and nonparenchymal cells, it was found that the latter had only 20% of the N-methylpurine-DNA glycosylase mRNA of hepatocytes, and that only the hepatocytes had induction of this expression after exposure to vinyl fluoride. Thus, the target cells for vinyl halide carcinogenesis have much lower expression of this DNA repair enzyme, which has been associated with etheno adduct repair.

Animals↗
PubMed1998

Decreased susceptibility of peripheral blood mononuclear cells from individuals heterozygous for a mutant CCR5 allele to HIV infection.

OBJECTIVE: Individuals homozygous for a deletion in the CCR5 gene (CCR5delta32/CCR5delta32) are resistant to HIV infection, indicating that this particular chemokine receptor plays a crucial role in the initiation of in vivo HIV infection. We investigated the effect of the heterozygote genotype (CCR5/CCR5delta32) on susceptibility of peripheral blood mononuclear cells (PBMC) to HIV infection. DESIGN: Sensitivity to HIV infection of PBMC from volunteers with either the CCR5/CCR5, CCR5/CCR5delta32, or CCR5delta32/CCR5delta32 genotypes was examined by challenging their PBMCs with serial titers of HIV isolates with different cellular tropisms. The genotype of the PBMCs was correlated with the lowest viral inoculum required to initiate productive infection with either three M-tropic HIV-1 isolates, (92RW009A, HIV-1ada, and HIV-1(59)), one dual-tropic HIV-1 isolate (92BR021), or two T-tropic HIV-1 isolates (92UG021 and 92UG029). RESULTS: PBMCs from the CCR5/CCR5delta32 group required a significantly higher inoculum (p value from .036 to .003) to become infected with these three M-tropic HIV-1 isolates than did PBMC from the CCR5/CCR5 group, but became infected after exposure to an inoculum of T-tropic HIV-1 isolates that was comparable to that which infected PBMCs from the CCR5/CCR5 individuals. CONCLUSIONS: The decreased susceptibility of PBMCs from individuals heterozygous for the CCR5 deletion to HIV infection by M-tropic HIV-1 isolates may provide a mechanistic explanation for the delayed progression of disease in some CCR5/CCR5delta32 individuals.

Alleles↗
PubMed1998

Isolation and characterization of the carbon-phosphorus bond-forming enzyme phosphoenolpyruvate mutase from the mollusk Mytilus edulis.

The enzyme phosphoenolpyruvate mutase was purified to homogeneity from the mollusk Mytilus edulis. The subunit size of the native homotetramer was determined to be 34,000 Da. The steady-state kinetic constants for catalysis of the conversion of phosphonopyruvate to phosphoenolpyruvate at pH 7.5 and 25 degrees C were measured at kcat = 34 s-1, phosphonopyruvate Km = 3 microM, and Mg2+ Km = 4 microM. The enzyme displayed a broad specificity for divalent metal ion activation; Co2+, Mn2+, Zn2+, and Ni2+ are activators, whereas Ca2+ is not. Analysis of the pH dependence of the Mg2+-activated mutase-catalyzed reaction of phosphonopyruvate revealed one residue that must be protonated (apparent pKa = 8.3) and a second residue that must be unprotonated (apparent pKa = 7.7) for maximal catalytic activity.

Amino Acid Sequence↗
PubMed1998

Stabilization of Liquid Crystal-in-Water Dispersion with Polymer/Surfactant Mixture: Nematic Curvilinear Aligned Phase Composite Film

The effect of nonionic surfactant (H(OCH2-CH2)8-OC6H4-C9H19) on the stability of liquid crystal-in-water dispersions stabilized by copolymers of acrylamide with hydrophobic monomers have been studied. It was observed that the addition of surfactant increases the stability of liquid crystal (LC) dispersion and improves the electrooptical properties of the nematic curvilinear aligned phase (NCAP) system. According to the interfacial tension measurements, it was proposed that the presence of surfactant allows to form the nonpolar microenvironment in the round of LC droplet and finally reduces the anchoring effect between LC and the polymeric wall. Copyright 1998 Academic Press. Copyright 1998Academic Press

Journal Article↗
PubMed1998

The effect of experimental spinal cord edema on the spinal evoked potential.

Experimental spinal cord edema was successfully produced in the cat intumescentia cervicalis by the infusion method of Marmarou. The water content around the infusion site significantly increased to 75.9% from the normal value of 69.8% of white matter in the lateral column, with the infusion of 20 microliters of autoserum. The edema was observed for a length of ca.20 mm, spreading mainly longitudinally in the lateral column. The spinal evoked potential was measured four times on the course of infusion and the N1 peak latency at the end of infusion did not show any significant difference compared to the value before infusion. This model may contribute to basic understanding of pathophysiology of spinal cord edema by changing the nature and the volume of infusate, and the location of infusion, according to the experimental purpose.

Afferent Pathways↗
PubMed1998

Expression of the antioxidant gene NKEF in the central nervous system.

Free radicals and the oxidative stress they impose can cause serious injury in the nervous system and contribute to pathology associated with a wide variety of degenerative and traumatic disorders. In this study, we examined the expression of an antioxidant defense gene, nkef, in human tissue and isolated populations of rat brain cells using Western and Northern blot analysis. NKEF protein was expressed in human brain, liver, kidney, muscle, and lung. The human endothelial cell line ECV expressed a 25-kDa band in addition to the 22-kDa band normally observed. In the central nervous system, a 22-kDa NKEF band was present in cortical gray and white matter, hippocampus, cerebellum, and spinal cord in roughly similar amounts. Expression of NKEF-A and NKEF-B subtypes was evaluated by Northern analysis of cultured cell types from embryonic rat brain. Astrocyte and microglia expressed both 22- and 25-kDa bands, whereas cortical neurons and oligodendrocytes contained only the 22-kDa protein band. Northern blot analysis of these cell types revealed low levels of NKEF-A message in neurons and oligodendrocytes, and relatively low levels of NKEF-B in microglia. Differential expression of these antioxidant defense genes may contribute to the selective vulnerability of brain cell types to specific kinds of oxidative stress.

Animals↗
PubMed1998

White cell subsets in apheresis and filtered platelet concentrates.

BACKGROUND: White cell (WBC)-reduced platelet concentrates (PCs) are defined by their absolute WBC count, a criterion which provides no information regarding the various WBC subsets contained in the PC. These heterogeneous cells are known to mediate different physiologic and pathophysiologic functions and account for distinct adverse transfusion responses. This study describes a method which allows the detection and quantification of these subsets and characterizes their presence in a variety of platelet components. STUDY DESIGN AND METHODS: Random-donor pooled PCs (RD PCs) and single-donor apheresis PCs (SD PCs) were studied. RD PCs consisting of 6 units of 2- to 3-day old PCs were randomly assigned to be filtered with one of four WBC-reduction filters from three different manufacturers (n=34). The residual WBCs were pelleted by centrifugation and isolated on a density gradient. The various WBC subsets were quantified by flow cytometry in unfiltered and filtered PCs using fluorescence and two-angle light scatter. SD PCs obtained with two manufacturer's systems and three processing protocols (n=30) were studied in like manner. RESULTS: WBC counts for non-WBC-reduced PCs averaged 3 x 10(8) in RD PCs and ranged from 8.6 to 9.6 x 10(6) per SD PC. Residual WBC counts in filtered PCs ranged from 2.3 x 10(4) to 2.2 x 10(5) and those in WBC-reduced SD PCs averaged 2.2 x 10(5) per unit. The data demonstrate significant phenotypic differences among PCs produced with various procedures. All SD PCs and two of four filtered RD PCs contained five WBC populations including granulocytes and monocytes, while RD PCs filtered with the remaining manufacturer's devices contained only lymphocytes. CONCLUSION: The data confirm that distinct phenotypic differences exist among PCs prepared with different devices and/or procedures. It is suggested that as for non-generic pharmaceuticals, the clinical benefits of these various PCs should be individually proved.

Filtration↗
PubMed1998

SIDS, abnormal nighttime REM sleep and CNS immaturity.

SIDS (Sudden Infant Death Syndrome) is the major cause of death in young, apparently healthy, infants, yet its etiology and pathogenesis remain unknown. SIDS peaks at 2-4 months, is more prevalent in the winter months and typically occurs in the early morning hours when most babies are asleep, suggesting that sleep may be part of the pathophysiological mechanism of SIDS. The sleep patterns of infants at high risk for SIDS were analyzed to test the hypothesis that there are abnormalities specific to nighttime sleep which may be indicative of a central nervous system (CNS) deficit that contributes to a high frequency of SIDS during the night. Electrophysiological sleep variables were recorded at monthly intervals in 1-6 months-old infants during the peak age of SIDS. The risk group (R) was resuscitated from a potentially life-threatening Sudden A-Ventilatory Event (S.A.V.E.) and compared to a group of control infants (C) with no family history of SIDS. The data representing four equal time intervals from 11 p.m.-11 a.m. show an abrupt, statistically significant increase in REM sleep from 2-5 a.m. in R infants. In C infants, time spent in REM sleep after 2 a.m. becomes progressively shorter while NREM sleep is proportionately longer. From 11 p.m.-2 a.m., however, R and C infants do not differ either in the duration or in the percent of total sleep time (TST) of REM sleep. We hypothesize that these REM sleep abnormalities in vulnerable infants are indicative of a pervasive CNS immaturity. The higher prevalence of SIDS in the cold winter months and in the early morning hours, when darkness is prolonged, is discussed in relation to the possible involvement of the circadian rhythm of melatonin.

Age Factors↗
PubMed1998

thy/liv-SCID-hu mice: a system for investigating the in vivo effects of multidrug therapy on plasma viremia and human immunodeficiency virus replication in lymphoid tissues.

Modified, human immunodeficiency virus (HIV)-inoculated thy/liv-SCID-hu mice were used to evaluate the in vivo efficacy of antiretroviral drugs. Ritonavir treatment alone initially suppressed plasma viremia, but the viremia recurred with the appearance of ritonavir-resistant HIV isolates. Multidrug therapy suppressed plasma HIV RNA to undetectable levels; however, plasma viremia returned after therapy was stopped, showing that the therapy did not completely suppress HIV infection in the thymic implant. When thy/liv-SCID-hu mice were treated with a combination of zidovudine, lamivudine, and ritonavir immediately after inoculation with HIV, cocultures of the thymic implants remained negative for HIV even 1 month after therapy was discontinued, suggesting that acute treatment can prevent the establishment of HIV infection. Thus, these modified thy/liv-SCID-hu mice should prove to be a useful system for evaluating the effectiveness of different antiretroviral therapies on acute and chronic HIV infection.

Animals↗
PubMed1998

Effectiveness of a sonic toothbrush in maintenance of dental implants. A prospective study.

This study assessed the efficacy of a sonic and a manual toothbrush in reducing plaque and gingivitis around dental implants. Subjects were randomly assigned to either sonic (n = 16) or manual (n = 15) study groups. Groups were balanced according to baseline levels of plaque and gingivitis. The plaque (PI), gingival (GI), and bleeding (BI) indices as well as probing depths were determined at baseline, and at 4, 8, 12, and 24 week follow-up visits. Mean scores per person were calculated for each clinical parameter. Oral hygiene habits, compliance and acceptance were also evaluated over the study period. Within group comparisons from baseline throughout the study, as well as between group comparisons (i.e., sonic versus manual), were determined. Overall, plaque, gingival, and bleeding indices in both groups were lower at each follow-up visit when compared to the baseline. Within group comparisons demonstrated that both the sonic toothbrush subjects and the manual toothbrush subjects had significantly lower PI, GI, and BI scores at each post-baseline visit (4, 8, 12, and 24 weeks) than at baseline (p<0.005). In addition, the sonic toothbrush subjects also had significantly lower probing depths at each post-baseline visit than at baseline (p < 0.005). Between group comparisons demonstrated that the sonic toothbrush subjects over time had significantly lower PI and BI scores around dental implants than the manual toothbrush subjects (Repeated measures MANOVA; PI, p = 0.01; BI, p = 0.017). The sonic toothbrush subjects had lower GI scores and reduced probing depths over time when compared to manual toothbrush subjects but these scores were not statistically significant (GI; probing depth, p > 0.05). No implant problems (e.g., loose screws) were attributable to the sonic toothbrush. Relevant to oral hygiene habits, subjects in both groups demonstrated a high level of compliance with their assigned toothbrush. Overall, the results of this study demonstrated that sonic toothbrushing significantly reduced plaque, gingival inflammation and bleeding, and probing pocket depths around implants over the 6-month trial period. It is concluded that sonic brushing is an effective means of dental implant maintenance.

Adolescent↗