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Biomedical subjects

S Y Yang

Publications and source records attributed to S Y Yang.

At least 109 records · Page 6Linked to original sources
PubMed1995

Clinical significance of admission hyperglycemia and factors related to it in patients with acute severe head injury.

BACKGROUND: Patients in the acute stage after a severe head injury often exhibit systemic stress responses. The aim of the present study is to assess in such patients the clinical significance of the change of catecholamines (CA) and of blood glucose. METHODS: The levels of serum of norepinephrine (NE), epinephrine (E), and dopamine (DA) were measured in 48 adults in the first 7 days after a severe head injury, and in 35 normal adults as a control group. The blood level of glucose at the time of admission was also measured. RESULTS: It was found that: (1) The serum CA level was significantly higher in the injured group than in controls. (2) The serum NE and E levels were higher in patients with lower Glasgow Coma Scores (GCS) and in the group of patients who did not survive. (3) The blood glucose level on admission was related both to the serum NE and E levels within the first 24 hours after head injury (r = 0.574, p < 0.05 and r = 0.410 and p < 0.05, respectively) and also the GCS and Glasgow Outcome Score (GOS) in these patients. (4) Patients with GCS of 3-4, 5-6, and 7-8 had mean glucose levels on admission of 12.805 +/- 3.205 mmol/L (228 +/- 67.23 mg/100 mL), 9.133 +/- 1.228 mmol/L, (160 +/- 12.28 mg/100 mL) and 6.029 +/- 1.228 mmol/L (107.66 +/- 21.9 mg/100 mL), respectively (p < 0.01). (5) Ninety percent of the patients with blood glucose levels of 9.6 mmol/L (171.4 mg/100 mL) at admission died within the first month; in the patients with lower glucose levels the mortality was 15%. CONCLUSIONS: These findings suggest that in the acute stage of severe head injury hyperglycemia and elevation of serum levels of CA are common components of the stress response, significant indicators of severity, and significant predictors of outcome.

Acute Disease↗
PubMed1995

Epidemiology of measles in Taiwan: dynamics of transmission and timeliness of reporting during an epidemic in 1988-9.

We analysed nation-wide reported measles cases during the 1988-9 epidemic and found that longer duration and wider spread were two major characteristics of the outbreak. All the 22 county/city index cases were reported with a delay of > 4 days and 64% were aged 5-14 years. This epidemic occurred mainly among 5-14-year-old school-children (59%), infants under 1 year (19%), and pre-school children (18%). The overall attack rate was 0.63 cases per 10,000 population, with the highest attack rate (7.4 cases per 10,000 population) occurring in infants. Among 280 confirmed cases < 15 months of age, 9-month-old infants (42 cases) had a higher risk of measles and peaked at 10 months (49 cases). This epidemic started in March 1988 among 5-9-year-old children in the northern suburban area, then spread to Taipei City and neighbouring counties or cities. It continued to spread from the northern to southern and western areas during the summer vacation and New Year holidays. Multiple logistic regression analysis showed that the delay of measles reporting was strongly associated with the cases infected early in the epidemic (OR = 6.9, P < 0.001) and reported from teaching hospitals (OR = 2.6, P < 0.001). The reappearance of high attack rates among 5-9-year-old children in the 1985 and 1988-9 measles epidemics in Taiwan indicated the persistence of pockets of susceptible individuals even after mass immunization.

Adolescent↗
PubMed1995

Locus-specific amplification of HLA class I genes from genomic DNA: locus-specific sequences in the first and third introns of HLA-A, -B, and -C alleles.

We have identified locus-specific sequences in the first and third introns flanking the polymorphic second and third exons of HLA class I genes. PCR primers derived from these conserved sequences produced DNA fragments of the expected sizes for each of the HLA-A, -B, and -C loci in the amplification of genomic DNA. PCR products generated using each of the locus-specific sets of primers displayed exquisite locus specificity, as assessed by hybridization with oligonucleotide probes specific for ten classical and non-classical HLA class I genes. Amplification with these primer sets was effective and specific for the HLA alleles tested under the given PCR conditions. When hybridized with oligonucleotides derived from shared polymorphic sequence motifs, reaction patterns of PCR products from each locus were precisely as expected from published or database sequences. Chemiluminescent signals generated from digoxygenin-ddUTP-labeled probes were even for all samples and as strong as those obtained in MHC class II typing. These locus-specific primer sets derived from intron sequences provide an effective means to amplify genomic DNA which will facilitate PCR-based HLA class I typing methods. This will also allow HLA class I typing to be conducted with greater precision, at lower cost, and faster than previously described class I typing methodologies.

Alleles↗
PubMed1995

The relative distribution of B35 alleles and their IEF isotypes in a HLA-B35-positive population.

The HLA-B35 serotype represents a group of antigens detectable by IEF, cytotoxic T cells, and by sequencing analysis. Four isotypes and eight alleles have been thus far reported. We have determined the relative frequencies of these B35 subtypes in a group of 203 unrelated people. Dot blot hybridization of PCR amplified products was performed using 23 sequence-specific oligo probes designed based on the EMBL HLA class I sequence database. The amplification was achieved by a pair of group-specific primers, producing approximately 600 bp fragments. By hybridization pattern analysis, we found that four alleles represent over 95% of the B35+ population, with relative frequency of 48.2% for B*3501, 23.7% for B*3502, 15.2% for B*3503, and 8.0% for B*3508. We also identified 3 individuals with B*3504 and one with B*3505, and seven samples with new patterns. B*3501 and B*3503 exactly correlated with the most common isotype B35.3, B*3502 and B*3504 with B35.2, B*3508 may be the B35.1 IEF isotype. The B*3505 was identified from an individual with B35 IEF variant form. Our study shows that the B35 antigen has a wide distribution of alleles, and that many more B35-related alleles may yet to be uncovered.

Alleles↗
PubMed1995

Allelic frequencies of the HLA-B17 antigen group: comparative analysis by serology, IEF and PCR-SSOP typing.

Current typing technology for class I HLA antigens uses serological and/or isoelectric focusing gel electrophoresis. DNA typing for the HLA class I antigens can accurately identify the class I genotype of individuals and cell lines. Here, we report correlation of DNA typing results with serological and IEF results for the B17 group. The B17 antigens are relatively common, being carried by almost 9% of Caucasians and 28% of blacks. In this study, five 10th International Histocompatibility Workshop cell lines carrying B17 and 106 individuals in 61 families carrying B17 were DNA typed for B17 using B17-allele-specific amplification and sequence specific oligonucleotide probe hybridization pattern analysis. 38 (55.07%) out of 69 unrelated haplotypes had B*5701, 23 (33.33%) had B*5801, 6 (8.70%) had B*5702, and 2 (2.90%) had B*5802. DNA typing results correlated well with serological and isoelectric focusing results. In general, there was high degree of agreement between all three methods, although heterozygosity for B17 poses a particular problem for serological and IEF methodology. Both B*5701 and B*5801 have the same electrophoretic mobility on IEF gel, corresponding to B17.2, B*5702 corresponds to B17.1, while B*5802 corresponds to B17.3.

Amino Acid Sequence↗
PubMed1994

The second kappa B element, kappa B2, of the HLA-A class I regulatory complex is an essential part of the promoter.

The MHC class I regulatory complex (CRC) contains the well characterized palindromic kappa B element, kappa B1, to which a number of nuclear factors are known to bind. This cis element plays an important role in controlling the transcription of MHC class I genes. In addition, the CRC contains a second kappa B element, kappa B2, which is located in tandem with the kappa B1 site, 5 bp upstream. In this study, from reporter gene transfection experiments, we present evidence that this kappa B2 site is as important as kappa B1 in regulating HLA-A locus transcription. Mutations introduced into either kappa B site reduced promoter activity to approximately the level obtained when the entire CRC was deleted. Electrophoretic mobility shift and supershift assays showed that the kappa B2-binding complex (BIII) contained a p65-like subunit, but apparently not the p50 subunit of NF-kappa B. Complex BIII also bound to the kappa B1 site, but the kappa B2 sequence was poorly recognized by the kappa B1-binding complex, BI, probably KBF1, the p50 homodimer. These results demonstrate that both kappa B sites are essential components of the promoter and suggest that they may function together to control MHC class I gene transcription.

Base Sequence↗
PubMed1994

Mid-P confidence intervals for the Poisson expectation.

Conventionally a confidence interval (CI) for the standardized mortality ratio is set using the conservative CI for a Poisson expectation, mu. Employing the mid-P argument we present alternative CIs that are shorter than the conventional ones. The mid-P intervals do not guarantee the nominal confidence level, but the true coverage probability is only lower than the nominal level for a few short ranges of mu. The implications for mid-P confidence intervals of various proposed definitions of two-sided tests for discrete data are discussed.

Confidence Intervals↗
PubMed1994

The regulatory complex of HLA class I promoters exhibits locus-specific conservation with limited allelic variation.

The extensive genetic polymorphism of the classical MHC class I molecules provides an important distinguishing feature of the host's immune system. They influence the selection and function of effector cells against tumor and virally infected cells. In these cells, class I molecules are often selectively suppressed. This suppression is locus specific and, in certain cases, allele specific. We analyzed the HLA class I promoter sequences that include class I regulatory complex (CRC) in a total of 41 well-characterized HLA homozygous B lymphoblastoid cell lines, using locus-specific oligonucleotide probes complementary to the overlapping CRC elements. These include kappa B1, kappa B2, IFN response sequence, the putative negative regulatory element, and the HLA counterpart of the H-2RII region that contains the retinoid x receptor beta binding motif. The CRC of HLA promoters displayed locus-specific conservation; however, limited allelic variation was observed in each of the cis elements. In some, variations were apparently generated by gene conversion. The palindromic kappa B1 site, which has an active role in enhancing promoter activity, was found to be conserved in almost all HLA-A and -B alleles, but not in HLA-C. The core DNA binding motif for retinoid x receptor beta was absent within the HLA CRC region. Sequence analysis of promoters from HLA-A31, -B13, and -Cw1 genomic clones, as well as pairwise interallelic and intra-allelic comparison with those of published alleles, showed that locus-specific conservation extended throughout the promoter sequences. Locus specificity and the allelic variation seen in the CRC regions may provide a structural basis for the selective modulation of HLA class I genes.

Alleles↗
PubMed1994

Primary structure of the large subunit of trifunctional beta-oxidation complex from pig heart mitochondria.

The amino-terminal and internal sequences of the isolated large subunit of trifunctional beta-oxidation complex from pig heart mitochondria were determined by Edman degradation. The results demonstrated that the sequence of this novel beta-oxidation enzyme is identical with the sequence recently reported for a porcine gastrin binding protein that serves as the gastrin receptor on parietal cell surfaces. Evidence is provided to show that it is unlikely that the porcine gastrin binding protein has such a sequence. The data lead us to conclude that the mature large subunit of porcine trifunctional beta-oxidation complex is composed of 727 amino acid residues with a calculated molecular weight of 79,113, while the precursor of this long-chain fatty acid oxidation enzyme has a mitochondrial presequence consisting of 36 residues and a calculated M(r) of 83,099.

Amino Acid Sequence↗
PubMed1994

Transsphenoidal microsurgical management of pituitary adenomas.

The transsphenoidal microsurgical operation is the best choice for most pituitary adenomas, whether or not there is an extension into the sphenoid or a supra-sellar extension without lateral spread. The advantage of this approach is that it allows selective removal of the adenoma and therefore can preserve normal pituitary function. In our series of 249 cases 79% had achieved a remission at follow-up one year or more after surgery. The surgical failure rate was 21%, and the mortality rate 0.8%. Complications occurred in 5.6%; most were temporary and minimal. The recurrence rate after transsphenoidal microsurgery was lower than that quoted in the literature after craniotomy. The smaller the size of the adenomas and the less the hormone abnormality preoperatively, the better the outcome.

Adenoma↗
PubMed1994

Nonrandom allelic variation in the regulatory complex of HLA class I genes.

Recently, we have demonstrated that the HLA class I regulatory complex (CRC) is conserved in a locus-specific manner with limited allelic variation. In this study, we have analyzed the CRC sequences of the alleles that showed variation from a total of 22 well-characterized, HLA-homozygous B-LCLs, using PCR amplification of genomic DNA and direct sequencing. We compared the sequences of these alleles with their respective locus consensus sequence at kappa B1, kappa B2, the IRS, the putative NRE, and the HLA counterpart of the H-2RII region, the R x R beta-binding site. The palindromic kappa B1 sequence, an active enhancer, was found to be conserved in all HLA-A and -B alleles and in one HLA-C allele. The sequences of the kappa B2 site showed locus-specific divergence with almost no allelic variation. The IRS is strictly locus specific and HLA-B and -C have identical sequences in this region. Variation in the putative NRE sequence and RII-kappa B2 junctional sequence was apparently generated by gene conversion between B and C loci. Each locus had two sequence patterns at the putative RII site. Overall, sequence analysis of variant alleles demonstrated that there is limited variation in a nonrandom fashion. These results may provide a structural basis for locus and allele-specific modulation of these genes.

Alleles↗
PubMed1994

The large subunit of the pig heart mitochondrial membrane-bound beta-oxidation complex is a long-chain enoyl-CoA hydratase: 3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme.

The subunit locations of the component enzymes of the pig heart trifunctional mitochondrial beta-oxidation complex are suggested by analyzing the primary structure of the large subunit of this membrane-bound multienzyme complex [Yang S.-Y. et al. (1994) Biochem. biophys. Res. Commun. 198, 431-437] with those of the subunits of the E. coli fatty acid oxidation complex and the corresponding mitochondrial matrix beta-oxidation enzymes. Long-chain enoyl-CoA hydratase and long-chain 3-hydroxyacyl-CoA dehydrogenase are located in the amino-terminal and the central regions of the 79 kDa polypeptide, respectively, whereas the long-chain 3-ketoacyl-CoA thiolase is associated with the 46 kDa subunit of this complex. The pig heart mitochondrial bifunctional beta-oxidation enzyme is more homologous to the large subunit of the prokaryotic fatty acid oxidation complex than to the peroxisomal trifunctional beta-oxidation enzyme. The evolutionary trees of 3-hydroxyacyl-CoA dehydrogenases and enoyl-CoA hydratases suggest that the mitochondrial inner membrane-bound bifunctional beta-oxidation enzyme and the corresponding matrix monofunctional beta-oxidation enzymes are more remotely related to each other than to their corresponding prokaryotic enzymes, and that the genes of E. coli multifunctional fatty acid oxidation protein and pig heart mitochondrial bifunctional beta-oxidation enzyme diverged after the appearance of eukaryotic cells.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1994

SSOP typing of the Tenth International Histocompatibility Workshop reference cell lines for HLA-C alleles.

HLA-C gene products are the most poorly understood of the HLA class I molecules because they express at low level on the cell surface compared to HLA-A and -B. However, recent evidence shows that HLA-C molecules are functionally competent in eliciting T-cell responses and in controlling NK-cell recognition. Approximately 20 to 50% of HLA-C alleles type "blank" in most populations. To provide a better definition of the HLA-C alleles, we analyzed 98 extensively characterized B-cell lines from the 10th International Histocompatibility Workshop. Selective HLA-C-specific DNA amplification of exons 2 and 3 from DNA prepared from the cell panel was achieved with the use of two sets of locus-specific primers. We used 64 sequence-specific oligonucleotide probes (SSOPs) complementary to variable sites in exons 2 and 3 to generate hybridization patterns. Twenty-five alleles were found among these patterns, including seven new alleles in the homozygous cell lines and seven potential new alleles in heterozygous cell lines. Differences between the new alleles and known alleles were generally small. Five major groups were identified in the Cw "blank" cells by the SSOP patterns. In addition, linkage between HLA-B specificities and HLA-C alleles was similar to previous observations. The present study demonstrated that SSOP typing was effective in identifying new alleles in homozygous typing cells but not in the heterozygous cells. Also, DNA typing can facilitate the identification of all HLA-C alleles, including those that serologically type as blanks. The HLA-C locus may be more polymorphic than was previously recognized.

Amino Acid Sequence↗
PubMed1994

DNA-based HLA typing of nonhematopoietic tissue used to select the marrow transplant donor for successful treatment of transfusion-associated graft-versus-host disease.

Transfusion-associated graft-versus-host disease (TAGVHD) is a rare and usually fatal complication of blood transfusion which can arise when immunocompetent lymphocytes from the donor of a cellular blood product are transfused into a severely immunocompromised recipient. We describe the case of an 8-month-old male with a severe combined immunodeficiency syndrome who developed TAGVHD after receiving an unirradiated transfusion. Serologic HLA typing of the parents, the patient, and the blood donor demonstrated the foreign origin of circulating lymphocytes, confirming the diagnosis of TAGVHD. The manifestations of TAGVHD did not respond to medical immunosuppressive therapy, and bone marrow transplantation was planned to treat the underlying immunodeficiency as well as the TAGVHD. By using DNA-based class I and class II HLA typing, the child's HLA type was determined from nonhematopoietic tissues. This information proved critical in selecting the bone marrow donor. The child received immunosuppression, myeloablation, and a T-depleted, maternal bone marrow graft mismatched at one HLA class II allele. Trilineage hematopoietic engraftment occurred within 3 weeks, and the child remains clinically stable with no evidence of TAGVHD more than 2 years after the transplant. This case illustrates that TAGVHD can be successfully treated by allogeneic bone marrow transplantation and that DNA-based HLA typing can play a unique role in the diagnosis and management of TAGVHD.

Bone Marrow Transplantation↗
PubMed1994

Do patients care about the age of their general practitioner? A questionnaire survey in five practices.

BACKGROUND: Previous work has suggested that some patients like their doctors to adopt a paternal or maternal role. AIM: This study set out to establish whether or not patients had preferences with regard to the age of their general practitioner and also to see whether they attributed various characteristics to younger or older doctors. METHOD: A self-administered questionnaire was given to 500 patients attending five general practices in Lothian, Scotland. RESULTS: Significant numbers of patients attributed different characteristics to older or younger doctors. Older doctors were more likely to be attributed positive attributes such as being thorough, kind, and willing to listen. The mean preferred age was 42 years. This varied slightly with the age of patients, from 40 years for patients under the age of 25 years to 45 years for those over 60 years. Of patients, 58% thought the age of their doctor was unimportant, but many were unhappy about seeing very young doctors (20-25 years, n = 195) or old doctors (66-75 years, n = 193). CONCLUSION: Patients did not seem concerned about the age of their doctor as long as he or she was of an age normally practising in the United Kingdom (27-65 years). They had some stereotyped views on the characteristics of older and younger doctors, but these were not held particularly strongly. Patients appeared to want a balance with the doctor being experienced and being up to date.

Adolescent↗