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Biomedical subjects

J H Yang

Publications and source records attributed to J H Yang.

At least 91 records · Page 5Linked to original sources
PubMed1995

Index of assessing functional status in elderly Japanese men.

We attempted to propose the equation of assessing the functional status of elderly adult Japanese men. A number of physical and motor performance measurements were collected from a group of 104 male volunteer subjects (mean age 76.4 +/- 5.8 years). Factor analysis with varimax criterion was applied to all the data. Five factors extracted were interpreted as follows: (1) coordination of the body, (2) flexibility of the trunk, (3) static balance, (4) muscular strength and endurance, and (5) cardiorespiratory fitness. Furthermore, the factor score was computed for each individual by each factor. Each of the five factors were weighted in accordance with its relative contribution to the total variance (or the size of eigenvalue). The weighted combination of factor scores was summed to generate an index of functional status (IFS). Next, IFS scores were computed for each individual and normalized to T scores. Then, a multiple linear regression analysis was performed with the factor analytically derived IFS scores as the dependent variable: IFS = -0.625X1 + 0.604X2 + 0.346X3 + 0.223X4 + 0.465X5 + 0.082X6 + 0.114X7 + 0.199X8 + 0.019X9 + 0.071X10 + 19.76; where X1 = walking around two chairs in a figure 8 (sec), X2 = manipulating pegs in a pegboard (num), X3 = vertical jump (cm), X4 = sit and reach (cm), X5 = estimated maximal oxygen uptake (ml/kg/min), X6 = balancing on one leg with eyes open (sec), X7 = grip strength (kg), X8 = trunk flexion from a standing position (cm), X9 = leg muscle endurance in a semi-squat position against a wall (sec), and X10 = balancing on one leg with eyes closed (sec) Thus, information on the 10 variables from five domains was statistically combined to a single score. The above equation was cross-validated in the other group of elderly men (n = 54). The mean IFS obtained for this group (50.0 +/- 8.3) was not significantly different from the validation group (50.0 +/- 10.0). It is apparent that the IFS has the potential to serve as another useful measure of high order, daily living activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Human skin mitochondrial DNA deletions associated with light exposure.

By polymerase chain reaction technique and DNA sequencing, we demonstrated the existence of multiple deletions in the mitochondrial DNA (mtDNA) of human skin tissues obtained from different body sites of an 86-year-old male farmer. We examined four types of skin tissues of different physiologic conditions, including sun-exposed, nonexposed, precancerous, and cancerous. The results showed that the common age-related 4977-base-pair (bp)-deleted mtDNA was present in different proportions in all the tissues examined. Quantitative PCR revealed that the amount of the 4977-bp-deleted mtDNA was associated with the physiologic conditions of the skin tissues. The sun-exposed skin tissues harbored higher level of the 4977-bp-deleted mtDNA (12.5%) than the nonexposed normal aged skin tissues (0.4%). On the other hand, in all the exposed skin tissues examined, the slower growing aged skin tissues harbored higher level of the 4977-bp-deleted mtDNA than the faster growing skin tissues in cancerous and precancerous skin tissues. In addition, we found at least four new deletions in the aforementioned different body sites with sizes of 7031, 7150, 7288, and 7485 bp, respectively. These findings provide an evidence of photooxidation-induced mtDNA mutations, since the deletions deposit in different patterns and proportions in different skin tissues of the patient. These findings suggest that, besides the intrinsic formation and accumulation of mtDNA deletions in human tissues during normal aging process, physiological and environmental factors may also play important roles in eliciting the deposit of deleted mtDNA molecules in the tissue cells.

Aged↗
PubMed1994

Catalytic activity of an RNA domain derived from the U6-U4 RNA complex.

U6 RNA contains two regions that are essential for proper splicing of nuclear precursor messenger RNA (pre-mRNA). A comparison of putative secondary structures of the U6-U4 RNA complexes from different phyla revealed a conserved domain that is similar to the catalytic hammerhead RNA motif. Although no catalytic activity was detected in the mammalian U6-U4 RNA complexes, two nucleotide changes in U6 RNA and one in U4 RNA conferred cleavage activity to the complex. Furthermore, the highly conserved domain of the wild-type complex, without the accompanying flanking regions, cleaved an RNA substrate and exhibited other characteristics of the hammerhead ribozyme. The possible involvement of this structure in pre-mRNA splicing is also discussed.

Base Sequence↗
PubMed1994

A specific 4977-bp deletion of mitochondrial DNA in human ageing skin.

Mitochondrial DNA (mtDNA) mutations have recently been proposed as important contributors to ageing and degenerative diseases. In this study, we applied the polymerase chain reaction technique to detect 4.977 bp-deleted mtDNA, the most common and abundant deletion of mtDNA, in normal human skin. None of the skin specimens from patients less than 60 years of age were found to bear this type of mtDNA deletion. The incidence of the 4977-bp-deleted mtDNA increased with advancing age. The incidence of the deletion was 20%, 46.7% and 83.4% for patients of the age groups of 61-70, 71-80, and 81-90 years, respectively. Moreover, the incidence of 4977-bp-deleted mtDNA was significantly higher in exposed skin than that in non-exposed skin. We suggest that mtDNA mutations are molecular events associated with the human skin ageing process.

Adolescent↗
PubMed1994

Cowden's disease: report of the first case in a Chinese.

A 19-year-old Chinese female presenting mucocutaneous manifestations including facial trichilemmomas, oral papillomatosis, and acral keratosis was diagnosed, according to the criteria proposed by Salem and Steck, as a definite case of Cowden's disease, although no members of her family were affected. The cutaneous reticulohistiocytic granuloma and congenital nystagmus of eyes that occurred in this case were new combinations in the syndrome. To the best of our knowledge, this is the first documented case of Cowden's disease in a Chinese.

Adult↗
PubMed1993

Purification and characterization of the valine sensitive acetolactate synthase from Serratia marcescens ATCC 25419.

The valine sensitive acetolactate synthase (ALS) isozyme from Serratia marcescens ATCC 25419 was purified to homogeneity. Analysis of the native molecular weight of the purified enzyme by the native pore gradient polyacrylamide gel electrophoresis indicated the molecular weight of about 178,000 and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the enzyme to be composed of two different types of subunits with molecular weights of 62,000 and 35,000. The molar ratio of the two polypeptides was estimated to be 1, suggesting that native enzyme is composed of two large subunits and two small subunits. The enzyme exhibits homotropic allosterism with pyruvate unlike other enteric ALS isozymes. The specificity ratio R (V[acetohydroxybutyrate]/V[acetolactate] = R.[alpha-ketobutyrate]/pyruvate]), of the enzyme was found to be 0 suggesting that the Serratia ALS has very high specificity for pyruvate. The pH optimum was around 7.5, and the enzyme was stable at 50 degrees C for 30 min. The pI value for the purified enzyme was 5.2. The concentration of branched chain amino acids for 50% inhibition of the enzyme was 0.1 mM for valine, and 1 mM for leucine and isoleucine, respectively.

Acetolactate Synthase↗
PubMed1993

Electrophysiological and pathological observations on experimental coxsackie B-3 viral myocarditis in mice.

Electrophysiological action of right ventricular myocardium examined by standard intracellular microelectrode technique and real-time microcomputer data processor system and histological and ultrastructural changes of myocardium in BALB/c mice infected with coxsackie B-3 virus from 3 days to 9 months were observed. It was found that electrophysiologic parameters of action potential changed very quickly at the early stage (3 days to 1 month) of the disease. Those abnormalities became most apparent by the 5-30th day, and 7 patterns of abnormal action potential occurred frequently within the same period. These changes were basically parallel to the myocardial lesions. At the late stage (3-9 months) the electrophysiological parameters were nearly normal, while the myocardial lesions decreased gradually. However, the abnormal patterns of action potential were still detected, even though they were improved gradually. The results suggest that myocardial damages caused by viral infection may lead to changes of cardiac electric action, which may be one of the factors in arrhythmias in the episode of viral myocarditis.

Action Potentials↗
PubMed1993

Neoplastic transformation of a human keratinocyte cell line by the v-fos oncogene.

To analyze the role of the fos oncogene in the growth of human epithelial cells, we have transfected a non-tumorigenic human epidermal keratinocyte line (RHEK-1) immortalized by the Ad12-SV40 hybrid virus with a plasmid carrying the v-fos gene together with plasmid pSV2-neo which confers resistance to neomycin. Individual neomycin-resistant clones were isolated and characterized with respect to morphological alteration. Of 16 independent clones analyzed, two appeared morphologically transformed and formed foci in culture. Only the two clones with a transformed phenotype were found by Southern blot hybridization analysis to contain the transfected v-fos gene. These clones formed colonies in soft agar and induced tumors when transplanted into nude mice. Analysis of fos specific mRNA and protein demonstrated that the transfected v-fos gene was expressed in these two clonal lines. These findings suggest that expression of the v-fos gene might facilitate the process of neoplastic transformation of human epithelial cells in culture. This appears to represent the first demonstration of the transforming potential of the v-fos gene in human cells.

Animals↗
PubMed1992

Neoplastic transformation of immortalized human keratinocytes by 2,3,7,8-tetrachlorodibenzo-p-dioxin.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is the most powerful carcinogen ever tested in animals. Recent epidemiological studies have suggested its carcinogenic potential in humans. In the present study, nontumorigenic human epidermal keratinocytes immortalized by adenovirus 12-simian virus 40 (Ad12-SV40) were transformed by exposures of TCDD equal to or greater than 0.1 nM for 2 wk. These transformed cells showed morphological alterations and induced carcinomas when transplanted into nude mice, whereas no such transformation phenotypes were observed with exposures of less than 0.1 nM for 2 wk. Primary human epithelial keratinocytes exposed to various concentrations of TCDD failed to show any evidence of transformation. Induction of aryl hydrocarbon hydroxylase activity was dose dependent, as was transformation. Thus, the carcinogenicity of TCDD in this human cell system appears to be an Ah receptor-mediated process. The present study represents the first evidence of neoplastic conversion of human cells exposed to this environmentally important chemical.

Animals↗
PubMed1992

Minimum ribonucleotide requirement for catalysis by the RNA hammerhead domain.

Several mixed DNA/RNA and 2'-O-methylribonucleotide/RNA analogues derived from the "hammerhead" domain of RNA catalysis have been prepared to study the minimum ribonucleotide requirement for catalytic activity. Oligodeoxyribonucleotides containing from seven to as few as four ribonucleotides are active in cleaving a substrate RNA. Predominantly deoxyribonucleotide-containing analogues have kcat values 20-300 and kcat/KM values approximately 100-2000 times lower than those of all-RNA ribozyme. In the case of predominantly 2'-O-methyl analogues, at least five ribonucleotides are needed to assure catalytic activity. In addition, both predominantly deoxyribonucleotide and 2'-O-methyl oligomers are at least 3 orders of magnitude more stable than an all-RNA ribozyme in incubations with RNase A and a yeast extract. These results suggest that the ribophosphate backbone is not a strict requirement for ribozyme-type catalysis. The identification of the four required ribonucleotides in the hammerhead catalytic domain provides valuable information for the rational design of chemical species having ribonuclease activities.

Base Sequence↗
PubMed1992

Open method versus capsulorrhaphy without drainage in the treatment of children with hepatic hydatid disease.

A recognized major postoperative complication of hepatic hydatid disease is accumulated hydrops leading to secondary infection in the residual cavity of the excised cyst. This study examined two methods of treating cystic hepatic hydatid disease in 43 children. A group of 22 children were treated by a new method of open drainage, 21 underwent capsulorrhaphy without drainage. There was no mortality or morbidity. The open method was associated with more rapid resolution of hydrops and quicker shrinkage of residual cavities, with efficacy over a median follow-up of 42 months.

Adolescent↗
PubMed1992

Effect of verapamil on acute coxsackievirus B3 murine myocarditis.

The effect of verapamil (Ver) on CVB3 murine myocarditis was investigated. It was found that Ver could aggravate the myocardial inflammation, increase the viral replication in myocardium, and raise mortality in mice with viral myocarditis when the drug was injected within the first 6 days after the CVB3 inoculation.

Acute Disease↗
PubMed1992

[Diagnosis and treatment of primary retroperitoneal tumors].

New diagnostic imaging methods could shed much light on the diagnosis and treatment of retroperitoneal tumors. From 1978 to 1988, 98 patients were admitted. Eighty patients were treated by surgery and the diagnosis proved by pathology. In patients with primary malignant retroperitoneal tumors, 27 were completely resected and 18 received palliative resection. Of 18 benign tumors, 16 were completely resected. In these 80 patients, biopsy was done in 17 patients. In patients with malignant tumors, a 5-year survival rate of 14% was obtained. In the resected benign tumors, a 5-year survival of 100% was obtained. Local recurrence was the chief cause of death.

Adolescent↗
PubMed1991

Cloning, nucleotide sequence and expression of the cytochrome c-552 gene from Hydrogenobacter thermophilus.

A cytochrome c-552 gene from a thermophilic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus, was cloned by using two oligonucleotide probes, which had been synthesized based on the known amino acid sequence of the protein. A 780-bp PstI-SphI fragment of the cloned DNA was sequenced and found to contain the entire structural gene coding for cytochrome c-552 bracketed by apparent Escherichia coli consensus sequences for initiation and termination of transcription. Cytochrome c-552 is synthesized in vivo as a precursor having an N-terminal signal sequence consisting of 18 amino acid residues. The cloned cytochrome c-552 gene without its own signal sequence was introduced into the pKK223-3 vector and expressed in E. coli upon induction with isopropyl beta-D-thiogalactoside. An expressed cytochrome c-552 protein had a methionine residue at the N-terminus since an initiation signal was introduced before the first amino acid residue of the mature cytochrome c-552. The heme c was attached to apo-type cytochrome c-552 in the cytoplasm of E. coli and the holoprotein had spectral properties, similar to the authentic cytochrome c-552 from H. thermophilus.

Amino Acid Sequence↗