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Biomedical subjects

M Kang

Publications and source records attributed to M Kang.

At least 55 records · Page 3Linked to original sources
PubMed1998

Inactivation of the p16 (INK4A) tumor-suppressor gene in pancreatic duct lesions: loss of intranuclear expression.

Pancreatic adenocarcinoma develops from histologically identifiable intraductal lesions that undergo a series of architectural, cytological, and genetic changes. Limited genetic evidence recently suggested that the p16 gene plays a role in the progression of these "duct lesions." Duct lesions were identified in pancreata from 33 pancreaticoduodenectomies performed for infiltrating adenocarcinoma. All of these infiltrating adenocarcinomas were previously shown to contain alterations in the p16 gene or its promoter. Monoclonal and polyclonal anti-p16 antibodies were used for histological immunodetection. One hundred twenty-six duct lesions were identified. Nine (30%) of 30 flat, 4 (27%) of 15 papillary, 37 (55%) of 67 papillary with atypia, and 10 (71%) of 14 carcinoma in situ duct lesions showed loss of p16 expression. These included 30% of the flat lesions versus 53% of the nonflat lesions and 29% of the nonatypical lesions versus 58% of the atypical lesions. For both comparisons, the differences were statistically significant (P = 0.036 and P = 0.003, respectively). Loss of p16 expression occurs more frequently, but not exclusively, in higher-grade duct lesions. These data support the hypothesis that pancreatic duct lesions are neoplastic and that they represent the precursors of infiltrating adenocarcinoma. Immunohistochemical detection of p16 provides a new technology to study the genetic alterations in and stages of progression of large numbers of morphologically defined pancreatic duct lesions.

Adenocarcinoma↗
PubMed1998

Ilio-psoas abscess in the paediatric population: treatment by US-guided percutaneous drainage.

BACKGROUND: Image-guided percutaneous drainage has been shown to be a safe and effective alternative to surgery in the management of psoas abscess in adults and adolescents. There is little information on its use in children. OBJECTIVE: To evaluate the safety and efficacy of US-guided percutaneous needle aspiration and catheter drainage of ilio-psoas abscesses. MATERIALS AND METHODS: A retrospective review of 14 children with 16 ilio-psoas abscesses (10 pyogenic and 4 tuberculous) who were treated by US-guided percutaneous needle aspiration (n = 5) or catheter drainage (n = 9) along with appropriate antimicrobial therapy. RESULTS: Percutaneous treatment was successful in 10 of the 14 patients; all showed clinical improvement within 24-48 h of drainage and subsequent imaging demonstrated resolution of the abscess cavities. Surgery was avoided in all of these ten patients except one, who underwent open surgical drainage of ipsilateral hip joint pus. Of the other four patients, two had to undergo surgical drainage of the ilio-psoas abscesses after failure of percutaneous treatment, one improved with antibiotics after needle aspiration failed to yield any pus, and one died of continuing staphylococcal septicaemia within 24 h of the procedure. There were no procedural complications. CONCLUSIONS: Percutaneous drainage represents an effective alternative to surgical drainage as a supplement to medical therapy in the management of children with ilio-psoas abscesses.

Child↗
PubMed1998

Structural modification of an orally active thrombin inhibitor, LB30057: replacement of the D-pocket-binding naphthyl moiety.

An amidrazonophenylalanine derivative LB30057 (2) was identified as a potent (Ki = 0.38 nM), selective, and orally active thrombin inhibitor. As a continuation of studies into benzamidrazone-based thrombin inhibitors, we have structurally modified compound 2 by replacing the naphthyl group with a variety of hydrophobic moieties. This study led to discovery of several compounds with significantly enhanced potency in thrombin inhibition without sacrificing selectivity against trypsin and oral absorption. The highest activity was obtained with compound 23 (Ki = 0.045 nM).

Administration, Oral↗
PubMed1998

Adolescents' knowledge of their health insurance coverage.

PURPOSE: To determine the accuracy of adolescents' self-report of health insurance coverage, using parents' report as a comparison standard. METHODS: Two separate samples of urban, school-based adolescents and their parents completed self-administered questionnaires about type of health insurance coverage. Sample 1 included 123 and Sample 2 included 93 adolescent-parent pairs. Percent agreement and the kappa statistic were determined for each of the sample groups, and for males versus females and older (> 14 years) versus younger (< or = 14 years) adolescents. RESULTS: In Sample 1, 33% of adolescent respondents responded "don't know" to the question about type of insurance coverage, and 4% left the question blank; in Sample 2, 3% answered "don't know," with none leaving the question blank. For Sample 1, we found a 57% rate of agreement of adolescents with their parents, and a corresponding kappa of .21. Females and older subjects demonstrated greater accuracy, with kappa's all in the range .13-.29. In Sample 2, 73% of subjects agreed with parents' report, with a kappa of .48. Females and older subjects also demonstrated greater accuracy, with the highest kappa of .59 demonstrated by older females. Excluding those responding with "don't know," we found overall percent agreement with parents of 87% in Sample 1 and 73% in Sample 2; the corresponding kappas were .47 and .51. Females demonstrated higher agreement with parents in both samples. The results stratifying by age were inconsistent. In Sample 1, privately insured subjects were more accurate reporters than those either on medical assistance or uninsured. In Sample 2, no differences were seen by type of insurance. CONCLUSIONS: Many adolescents do not know their health insurance coverage status. However, for those who did claim to know, acceptable rates of accuracy using both percent agreement and the kappa statistic were demonstrated. Further research is needed to determine how information about insurance is communicated to adolescents and how this knowledge affects access to and use of health services.

Adolescent↗
PubMed1998

Social role functioning by adolescents with psychiatric disorders.

OBJECTIVE: To identify aspects of social role functioning that are impaired in adolescents with specific psychiatric disorders in order to improve the psychiatric taxonomy and clinical knowledge base. METHOD: Adolescents in four urban public schools were screened for mental health problems. Structured psychiatric interviews (National Institute of Mental Health Diagnostic Interview Schedule for Children Version 2.2) with 288 adolescents and their mothers were used to identify youths with psychiatric disorders, and 10 aspects of social role functioning were assessed. Aspects of social role functioning that discriminated between youths with and without psychiatric disorders and between those with emotional disorders and those with disruptive disorders were identified for boys and for girls. RESULTS: Boys with any type of disorder and all youths with disruptive disorders had significant, consistent impairment in academic performance and several other areas of functioning. Youths with emotional disorders, especially girls, demonstrated impairment in social activity participation and peer acceptance, but girls with disorders were not as consistently different from those without as were the boys with emotional disorders. CONCLUSIONS: Role functioning differs in important ways between youths with and without psychiatric disorders and between girls and boys with disorders. The results underscore the importance of investigating observable aspects of role behavior in order to improve the timely detection and effective management of psychiatric disorders in youth.

Adolescent↗
PubMed1998

A taxonomy of adolescent health: development of the adolescent health profile-types.

OBJECTIVES: The aim of this study was to develop a taxonomy of health profile-types that describe adolescents' patterns of health as self-reported on a health status questionnaire. The intent was to be able to assign individuals to mutually exclusive and exhaustive groups that characterize the important aspects of their health and need for health services. METHODS: Cluster analytic empirical methods and clinically based conceptual methods were used to identify patterns of health in samples of adolescents from schools and from clinics that serve adolescents with chronic conditions and acute illnesses. Individuals with similar patterns of scores across multiple domains were assigned to the same profile-type. Results from the empirical and conceptually based methods were integrated to produce a practical system for assigning youths to profile-types. RESULTS: Four domains of health (Satisfaction, Discomfort, Risks and Resilience) were used to group individuals into 13 distinct profile-types. The profile-types were characterized primarily by the number of domains in which health is poor, identifying the unique combinations of problems that characterize different subgroups of adolescents. CONCLUSIONS: This method of reporting the information available on health status surveys is potentially a more informative way of identifying and classifying the health needs of subgroups in the population than is available from global scores or multiple scale scores. The reliability and validity of this taxonomy of health profile-types for the purposes of planning and evaluating health services must be demonstrated. That is the purpose of the accompanying study.

Acute Disease↗
PubMed1998

Reliability and validity of the adolescent health profile-types.

OBJECTIVES: The purpose of this study was to demonstrate the preliminary reliability and validity of a set 13 profiles of adolescent health that describe distinct patterns of health and health service requirements on four domains of health. METHODS: Reliability and validity were tested in four ethnically diverse population samples of urban and rural youths aged 11 to 17-years-old in public schools (N = 4,066). The reliability of the classification procedure and construct validity were examined in terms of the predicted and actual distributions of age, gender, race, socioeconomic status, and family type. School achievement, medical conditions, and the proportion of youths with a psychiatric disorder also were examined as tests of construct validity. RESULTS: The classification method was shown to produce consistent results across the four populations in terms of proportions of youths assigned with specific sociodemographic characteristics. Variations in health described by specific profiles showed expected relations to sociodemographic characteristics, family structure, school achievement, medical disorders, and psychiatric disorders. CONCLUSIONS: This taxonomy of health profile-types appears to effectively describe a set of patterns that characterize adolescent health. The profile-types provide a unique and practical method for identifying subgroups having distinct needs for health services, with potential utility for health policy and planning. Such integrative reporting methods are critical for more effective utilization of health status instruments in health resource planning and policy development.

Adolescent↗
PubMed1998

Satiation and masticatory function modulated by brain histamine in rats.

Both the ventromedial hypothalamus (VMH) and the mesencephalic trigeminal sensory nucleus (Me5) are densely innervated by histaminergic neurons. The depletion of neuronal histamine (HA) from the Me5 by the bilateral microinfusion of 448 nmol/rat alpha-fluoromethylhistidine (FMH), a specific suicide inhibitor of histidine decarboxylase, reduced the eating speed and prolonged meal duration, while leaving the meal size unaffected. HA depletion from the VMH increased the size of the meal and prolonged its duration, but not the eating speed. When the HA turnover rate was measured at 15 min after the scheduled feeding following fasting for less than 24 hr, the rate increased in the region including the Me5, but not in the hypothalamus. The turnover rate reached higher levels at 60 min in both regions. Gastric intubation of an isocaloric liquid diet or an equivolume of water with the liquid diet abolished the increase in HA turnover both in the Me5 region and the hypothalamus. The present findings indicate that brain HA thus modulates satiation through both the VMH and masticatory function as well as due to the action of the Me5. The HA function activated by mastication began earlier in the Me5 and later in the hypothalamus due to a signal originating from the oral proprioceptors and initiated by chewing.

Animals↗
PubMed1997

Evolution of magnetic and superconducting fluctuations with doping of high-Tc superconductors

Electronic Raman scattering from high- and low-energy excitations was studied as a function of temperature, extent of hole doping, and energy of the incident photons in Bi2Sr2CaCu2O8+/-delta superconductors. For underdoped superconductors, short-range antiferromagnetic (AF) correlations were found to persist with hole doping, and doped single holes were found to be incoherent in the AF environment. Above the superconducting (SC) transition temperature Tc, the system exhibited a sharp Raman resonance of B1g symmetry and energy of 75 millielectron-volts and a pseudogap for electron-hole excitations below 75 millielectron-volts, a manifestation of a partially coherent state forming from doped incoherent quasi particles. The occupancy of the coherent state increases with cooling until phase ordering at Tc produces a global SC state.

Journal Article↗
PubMed1997

Ki-67, p53, and Bcl-2 expression of serrated adenomas of the colon.

To investigate epithelial cell proliferation and oncoprotein expression of the serrated adenoma, a term that has been used synonymously with mixed hyperplastic and adenomatous polyp, immunohistochemical staining using polyclonal antibodies against Ki-67 and p53, and a Bcl-2 monoclonal antibody, was performed and the results compared with those in hyperplastic polyps and tubular adenomas. A total of 20 serrated adenomas all characterized by a serrated glandular pattern, contained immature goblet cells, upper crypt zone mitotic figures, and a few nucleoli within the epithelial cells. Twenty hyperplastic polyps and 20 tubular adenomas (all with low-grade dysplasia) were examined, and lesions that contained separate areas of hyperplastic and adenomatous glands were excluded. The Ki-67-positive rate in the middle zone of the crypts in serrated adenomas was significantly higher than in hyperplastic polyps but lower than in tubular adenomas; a similar tendency was also noted for the upper zone. Both serrated adenomas and hyperplastic polyps demonstrated Bcl-2-positive reactivity that was essentially limited to the lower crypt zone, while in contrast, involvement in tubular adenomas often extended to the middle zone. No p53 overexpression was found in any category. These results suggest that serrated adenomas may be committed to independent growth.

Adenoma↗
PubMed1997

Release of glutathione from erythrocytes and other markers of oxidative stress in carbon monoxide poisoning.

Rats exposed to CO in a manner known to cause oxidative stress in brain exhibited a twofold increase in plasma levels of oxidized proteins, thiobarbituric acid-reactive substances (TBARS), oxidized glutathione (GSSG), and reduced glutathione (GSH). Changes were neither directly related to hypoxic stress from carboxyhemoglobin nor significantly influenced by circulating platelets or neutrophils. Treatment with the nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester inhibited elevations in GSH and GSSG but not changes in oxidized proteins or TBARS, suggesting that two oxidative mechanisms may be operating in this model and that GSH and GSSG elevations involved nitric oxide-derived oxidants. Elevations of blood GSH and GSSG occurred at different anatomic sites, indicating that no single organ was the source of the increased peptides. Animals that underwent exchange transfusion with a hemoglobin-containing saline solution did not exhibit elevations in GSH and GSSG, suggesting that blood-borne cells released these peptides in response to oxidative stress. In in vitro studies, erythrocytes, but not platelets and leukocytes, responded to oxidative stress from peroxynitrite by releasing GSH, whereas no release was observed in response to nitric oxide or superoxide. Glucose, maltose, and cytochalasin B, agents that protect extracellular components of the hexose transport protein complex from oxidative stress, prevented GSH release. The data indicate that nitric oxide-derived oxidants are involved in CO-mediated oxidative stress within the vascular compartment and that elevations of several compounds may be useful for identifying exposures to CO likely to precipitate brain injury.

Animals↗
PubMed1997

Autonomic and behavioral thermoregulation in guinea pigs during postnatal maturation.

Serial experiments were carried out on seven chronically instrumented Hartley-strain guinea pigs at 1, 3, and 5 wk of age to define their autonomic and behavioral thermoregulatory profiles and to test the hypothesis that they have the mechanisms in place shortly after birth that allow them to optimize their energy expenditure for thermoregulation by selecting a thermal environment that requires the lowest metabolic oxygen requirements. Each animal was studied in both a thermocline to determine selected ambient temperature and in a metabolic chamber to determine the thermoregulatory response to forced changes in ambient temperature. In the thermocline, the guinea pigs at all postnatal ages selected an ambient temperature that placed core temperature, oxygen consumption, thermal conductance, heart rate, and respiratory rate at levels comparable to those observed at ambient temperatures in which minimal oxygen consumption occurred in the metabolic chamber. Thus our experiments provide evidence that guinea pigs have the neurophysiological mechanisms in place shortly after birth that allow them to optimize their energy expenditure for thermoregulation by selecting a thermal environment that corresponds to the lowest metabolic oxygen requirements.

Aging↗
PubMed1997

The impact of asthma on the health status of adolescents.

OBJECTIVE: To identify a characteristic pattern of health and illness for adolescents with asthma, we compared the health status of teenagers with asthma to those without asthma using a recently developed generic health status instrument, the Child Health and Illness Profile, Adolescent Edition (CHIP-AE). METHODS: This was a cross-sectional survey using a school sample of 3109 teenagers. Participants completed the CHIP-AE during school in northern Baltimore City, rural western Maryland, and rural Arkansas. The health and functioning scores of teens without asthma ("well" group) were compared with those with asthma with and without recent wheezing. RESULTS: Of the 12% who reported that a physician had ever told them they had asthma, 50% had problems with wheezing in the past 28 days. Compared with well teenagers, those with asthma and recent wheezing had lower perceived well-being, more physical and emotional symptoms, greater limitations in activity, more comorbidities, and more negative behaviors that threaten social development. These findings held true in multivariable regression models that controlled for sociodemographics and sites of data collection. Teenagers with asthma without recent wheezing reported a greater number of comorbidities than well teens and showed similar trends in health status as those with recently symptomatic asthma. CONCLUSIONS: Multiple aspects of adolescent health status are affected by asthma, particularly if it is recently symptomatic. These results argue for incorporating a generic health status instrument, such as the CHIP-AE, in studies that document the health needs or outcomes of medical care for populations of teenagers with asthma.

Adolescent↗
PubMed1996

Stability and folding of precursor and mature tryptophan-substituted ribose binding protein of Escherichia coli.

A mutant ribose binding protein (RBP) of Escherichia coli was obtained by site-directed mutagenesis, replacing Phe-187 in the wild-type RBP (WT-RBP) with a Trp residue, in order to compare its stability and folding behavior with those of the WT-RBP. The equilibrium unfolding properties and the folding kinetics of these proteins were monitored by fluorescence and circular dichroism (CD). For both WT-RBP and the Trp-substituted RBP (Trp-RBP), the conformational stabilities of the precursor proteins and the mature proteins were the same, indicating that the signal peptide had no influence on the property of the mature domain. The Phe/Trp substitution in the mature domain, however, brought about a significant decrease in the conformational stability. The signal peptide had an appreciable retarding effect on the folding of the precursor Trp-RBP as was reported for the WT-RBP. Refolding kinetics of the WT-RBP and Trp-RBP showed a two-step reaction when monitored by fluorescence and by CD.

Bacterial Proteins↗
PubMed1996

Persistent reduction of GABA(A) receptor-mediated inhibition in rat hippocampus after chronic intermittent ethanol treatment.

GABA(A) receptor-mediated function was studied in rats treated with chronic intermittent ethanol (CIE). Rats were given 60 doses of 6g/kg ethanol every 24 h by gastric intubation, with repeated intoxicating and withdrawal episodes leading to a kindling-like increase in seizure susceptibility (Kokka et al., Alcohol: Clin. Exp. Res., 17 (1993) 525-531). Efflux of 36Cl-, evoked by application of muscimol, a measure of GABA(A) receptor function, was examined in 300 mu m slices obtained from frontal, parietal, and temporal cortex, hippocampus, and inferior colliculus, one day after the last administration of ethanol. Compared to controls, the 36Cl- efflux in hippocampal slices of CIE rats was significantly reduced by 29%, while there were no changes in the other brain regions studied. In hippocampal slices, paired-pulse inhibition in CA1 pyramidal neurons, measured extracellularly using homosynaptic orthodromic stimulation at an interval of 10 ms, was significantly reduced in CIE rats. A significant decrease by 40% both at 2 and 40 days after 60 doses of ethanol was found, implying a persistent decrease in GABA(A) receptor-mediated inhibition in CIE rats. These reductions in paired-pulse inhibition are consistent with the decrease in the pentylenetetrazol (PTZ) seizure threshold which was previously observed in CIE rats. Therefore, we suggest that this reduction of GABA(A) receptor-mediated inhibition contributes to the persistent increase in seizure susceptibility of CIE rats.

Animals↗
PubMed1996

Percutaneous transluminal balloon pulmonary valvuloplasty using domestic balloon catheter for congenital pulmonary valve stenosis in children.

OBJECTIVE: To estimate the effect of percutaneous balloon pulmonary valvuloplasty (PBPV) using domestic balloon catheter for congenital pulmonary valve stenosis (PVS) in infants and children. PATIENTS AND METHODS: The data of 70 patients aged from 1.5 to 12 years (mean 5.5 +/- 3.4 years) who underwent PBPV using domestic balloon catheter for PVS in our institution were reviewed. Sixty-six patients had dome-shaped valve stenosis, and 4 had displastic valve stenosis. SaO2 reduced in 5 patients and associated open foramen ovale was noted in 23. Predilatation, right ventricular systolic pressure ranged from 60 to 234 mmHg (mean 115.75 +/- 36.15 mmHg). The systolic gradient (delta P) from right ventricle to pulmonary artery was 89.92 +/- 38.25 mmHg. Balloon diameter was selected 120%-142% of pulmonary valve annulus diameter (mean 132%). All patients were followed up for 3 months-4 years by means of clinical examination. ECG, 2D-UCG, and Doppler-UCG. RESULTS: After dilatation, delta P reduced from 89.92 +/- 38.25 to 14.65 +/- 11.40 mmHg (P < 0.001). The rate of decrease in transvalve gradient (delta P) was 83.7%. No patients experienced procedure-related events. Mid-term follow-up showed that no patients had clinical and instrumental complications. Doppler and ECG analyses showed that delta P did not change significantly similar to immediate gradient after PBPV and right ventricular hypertrophy disappeared progressively 6 months after PBPV. CONCLUSIONS: PBPV is a useful, safe and definitive procedure in the treatment of isolated PVS in infants and children. The properties and features of the balloon catheter produced by Shanghai Med-Tech Factory are similar to those of Med-Tech balloon catheter of U.S.A.

Catheterization↗