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Biomedical subjects

C Y Yang

Publications and source records attributed to C Y Yang.

At least 217 records · Page 12Linked to original sources
PubMed1991

Heart diseases following radiotherapy.

Three women had cardiac complaints 10-17 years after a radical mastectomy and radiotherapy for cancer of the left breast. Their ages were 42, 43 and 57 years, respectively. The first patient had a precocious coronary artery disease (CAD). She had segmental stenosis in the middle and distal portions of the left main coronary artery and pericardial fibrosis. Symptoms and signs of severe pericardial constriction became the problem after bypass surgery. She died 1 year later due to cardiorespiratory failure. The second case had sick sinus syndrome presenting a prolonged pause for 12 seconds alternating with tachy- and bradyarrhythmias, a complete atrio-ventricular block in association with pericardial effusion plus aortic and mitral valvular regurgitation. The condition improved after the implantation of a permanent pacemaker. To date, this is a very rare complication of radiation induced panconduction disturbance. The third patient had significant stenosis in the proximal portion of the left anterior descending coronary artery and myocardial fibrosis was proven by an endocardial biopsy. She had an uneventful course after medical treatment.

Adult↗
PubMed1991

The management of ingested foreign bodies in the upper digestive tract: a retrospective study of 49 cases.

Forty-nine cases of accidental foreign body ingestion treated in our unit were reviewed. Fish bones were the commonest foreign body ingested by adults while coins and pins accounted for most cases in the paediatric age group. All except one patient had endoscopy performed, majority with flexible endoscope. Foreign bodies were detected and successfully removed endoscopically in 23 patients except one. In another 12 patients, foreign bodies were demonstrated by chest X-ray or Barium meal but at the time of endoscopy, they had passed beyond the reach of the endoscope. For the remaining 13 patients, despite having a history of foreign body ingestion and retrosternal pain, subsequent investigation failed to demonstrate the foreign bodies. Barium contrast studies were performed in 31 cases, with 5 false negative and 2 possible false positive findings. There were 2 serious complications related to foreign body ingestion, one had empyema thoracis and another died of massive bleeding due to esophageal carotid fistula.

Adolescent↗
PubMed1991

Amino acid sequence of rabbit apolipoprotein E.

The complete amino acid sequence of rabbit apolipoprotein E (apoE) was determined by generating three sets of peptides using cyanogen bromide, endoproteinase AspN, and Staphylococcus aureus V8 protease to cleave the protein. Through twenty cycles of sequence analysis on the whole protein, glutamic acid was identified as the N-terminal residue of rabbit apoE; the C-terminus of the protein was identified as glutamine. Based on the sequence of 294 amino acid residues determined by protein structure analysis, the molecular weight of rabbit apoE was determined to be 33,684. The protein sequence differed from the cDNA inferred sequence in 19 positions, only one of which could be attributed to microheterogeneity. The corrected amino acid sequence of rabbit apoE shares 80% homology with the human apoE sequence, 4% greater homology than that inferred from the cDNA sequence. The great similarity in the amino acid sequences of human and rabbit apoE suggests that their physical and physiological properties may also be similar. This homology and the relative ease with which apoE is isolated from rabbit plasma make it possible to conduct some in vitro experiments with the rabbit apoprotein that would have direct relevance to human apoE, but would be difficult or impossible with the human counterpart because of the quantity of protein required.

Amino Acid Sequence↗
PubMed1990

Coding sequences of the tal-1 gene are disrupted by chromosome translocation in human T cell leukemia.

The tal-1 proto-oncogene encodes a helix-loop-helix DNA-binding protein that has been implicated in the formation of T cell acute lymphoblastic leukemia (T-ALL). Patients with T-ALL harbor structural rearrangements of tal-1 that result from either local DNA deletion or t(1;14)(p34;q11) chromosome translocation. By analyzing t(1;14)(p34;q11) chromosomes from a series of patients, we have now identified a discrete region of tal-1 wherein most of the translocation breakpoints occur. Moreover, mapping of tal-1 genomic DNA revealed that coding exons are situated on both sides of the t(1;14)(p34;q11) major breakpoint region. Hence, the translocated allele of tal-1 is truncated in a manner that reduces its amino acid coding potential.

Adult↗
PubMed1990

The chromosome translocation (11;14)(p13;q11) associated with T cell acute leukemia. Asymmetric diversification of the translocational junctions.

The t(11;14)(p13;q13) translocation associated with T cell acute lymphocytic leukemia generates two abnormal chromosomes, designated 11p+ and 14q-. To investigate the mechanism of t(11;14)(p13;q11) formation, we analyzed the translocation junctions of 11p+ and 14q- from two patients. The 11p+ junctions consisted of precise fusions of a pseudo recombination signal from chromosome 11 and the downstream recombination signal of the TCR D delta 2 gene segment from chromosome 14. In contrast, the 14q- junctions from both patients were diversified by random loss and addition of nucleotides at the translocation site. This asymmetric pattern of junctional diversification is typical of normal Ig/TCR gene rearrangement, and therefore implies that the t(11;14)(p13;q11) translocation arose due to aberrant activity of the Ig/TCR recombinase.

Adult↗
PubMed1990

Determination of cysteine on low-density lipoproteins using the fluorescent probe, 5-iodoacetamidofluoresceine.

Using the fluorescent sulfhydryl probe, 5-iodoacetamidofluoresceine, to label the free sulfhydryl of low-density lipoprotein, the positions of two cysteine residues in apolipoprotein B were located. The tryptic peptides containing the fluorescent probe were isolated by high-performance liquid chromatography systems and sequenced by automatic techniques. The free cysteine residues of apolipoprotein B-100 on low-density lipoprotein are located at positions 3734 and 4190, either or both of which can potentially form a disulfide linkage with apolipoprotein(a) in lipoprotein(a).

Amino Acid Sequence↗
PubMed1990

Phospholipase A2 as leukotriene B4 secretagogue for human polymorphonuclear leukocytes.

High levels of soluble phospholipase A2 (PLA2) activity have been detected in tissues fluids associated with inflammatory diseases. However, the cellular origin for PLA2 has not been demonstrated. Several groups of investigators have proposed that platelets, macrophages and chondrocytes may be the cellular source of this enzyme. In fact, soluble PLA2 is secreted extracellularly from rabbit and rat chondrocytes and from human synovial cells in response to cytokine stimulation (1). PLA2 activity has been shown to be increased upon stimulation by the chemotactic peptide (f-met-leu-phe) and thrombin in neutrophils and platelets (2). PLA2 has been found to have pro-inflammatory effects and causes a dose dependent infiltration of leukocytes and increased vascular permeability (3). The vascular actions of PLA2 have been proposed to be mediated through the release of prostaglandin E2 and thromboxane (4). We have reported that purified PLA2 from snake venom stimulated the release of leukotrienes and lipoxins from endogenous sources in porcine leukocytes. However, there is no information regarding the mechanism of action of human PLA2 on inflammatory cells and the generation of leukotrienes. In this report, we present evidence that PLA2 isolated from human platelets can stimulate the production of leukotriene B4 from human polymorphonuclear leukocytes. These results suggest that soluble PLA2 may function as a secretagogue of LTB4 in inflammatory sites and further amplify the inflammatory processes by inducing chemotaxis of circulating leukocytes.

Arachidonic Acid↗
PubMed1990

Analysis of the carbohydrate composition of glycoproteins by high-performance liquid chromatography.

A procedure for rapid and sensitive analysis of carbohydrate in glycoproteins is described. After methanolysis and benzoylation of the monosaccharides and carbohydrates of a glycoprotein, the derivatized sugars were analyzed by reverse-phase high-performance chromatography using a Vydac C18 stationary phase and a mobile phase composed of a water/acetonitrile gradient. The advantages of this procedure over previously described methods are (1) the simple binary solvent system which is used requires no buffering salts and (2) separate sets of peaks from individual sugars obviate the usual need to reacetylate sugar amino groups.

Carbohydrates↗
PubMed1990

Isolation and characterization of sulfhydryl and disulfide peptides of human apolipoprotein B-100.

Twenty-three of the 25 cysteine residues in apolipoprotein B-100 have been isolated directly from tryptic or peptic peptide mixtures. Sixteen cysteine residues exist in disulfide forms: Cys-1-Cys-3, Cys-2-Cys-4, Cys-5-Cys-6, Cys-7-Cys-8, Cys-9-Cys-10, Cys-11-Cys-12, Cys-13-Cys-14, and Cys-20-Cys-21. All of these except Cys-20-Cys-21 are recently discovered disulfide linkages. In addition to Cys-22 and Cys-24, which have been described as sulfhydryls on low density lipoprotein, Cys-15 to Cys-18 and Cys-23 are in the reduced form. Cys-19 and Cys-25 are not yet confirmed. Our results revealed that all identified disulfide linkages are located in the trypsin-releasable regions and that all except Cys-1-Cys-3 and Cys-2-Cys-4 are linked to the neighboring cysteine. We propose a linear model of apolipoprotein B-100 in low density lipoprotein that wraps around the low density lipoprotein molecule.

Amino Acid Sequence↗
PubMed1990

Ultrasonographic difficulties and pitfalls in diagnosing primary carcinoma of the gallbladder.

In order to more specifically define gallbladder carcinoma with real-time ultrasonography, a retrospective study was performed involving 29 sonographically false-negative and 22 sonographically false-positive cases of gallbladder carcinoma. Among the false negative cases, 18 (62.1%) were diagnosed as gallbladder stone only, 6 cases (20.7%) were incorrectly diagnosed as either acute or chronic cholecystitis, 2 cases (6.9%) were diagnosed as bile sludge, 2 cases (6.9%) were diagnosed as polyps, and 1 case (3.4%) was diagnosed as liver tumor. In false-positive cases, 8 (31.8%) were erroneously diagnosed as liver tumor. In false-positive cases, 7 (31.8%) were erroneously diagnosed as a mass projecting from the gallbladder wall but were pathologically proven to be polyps (4 cases) or bile sludge (3 cases); 8 cases (36.4%) were incorrectly diagnosed due to irregular thickening of the gallbladder wall but histology revealed them to be acute (3 cases) or chronic (5 cases) cholecystitis. Seven cases (31.8%) had a solid mass in porta hepatis, indicating gallbladder carcinoma; of these, 2 cases were lumps of bile sludge and 5 cases were acute cholecystitis with empyema. The differentiation of gallbladder carcinoma from cholecystitis (acute or chronic), polyps, and bile sludge is sometimes very difficult. With an understanding of the sonographic pitfalls and difficulties in the diagnosis of gallbladder carcinoma, a more specific diagnosis may be made.

Carcinoma↗
PubMed1990

[Frequency distribution of birth weight and gestational age in Taiwan].

Perinatal mortality rate is closely related to birth weight. We collected data on 35919 single liveborn babies at a teaching hospital in central Taiwan between 1977 and 1987, excluding 1980. The average birth weights of the two sexes combined, and of male and female live births separately, were 3163 +/- 486 gm, 3211 +/- 499 gm (N = 18865) and 3110 +/- 466 gm (N = 17054), respectively. The average gestational age of these live births was 39.7 +/- 2.1 weeks. The skewness and kurtosis of birth weight and gestational age distribution were -0.86 and 3.13, and -2.11 and 10.29, respectively. The two distributions indicated high kurtosis and left skewness, and were approximately normally distributed. Because birth weight and gestational age are highly associated, the skew-to-left residual distribution of birth weight might have been induced by low gestational age. Babies of low gestational age might not be able to develop mature organs and tissues, which, thus, results in high perinatal mortality. The distribution of birth weight intersects the normal curve within the region between 1500 gm and 2000 gm, which means that we may divide it into a predominant part and a residual part. Many articles have shown that the residual part is highly correlated to perinatal mortality rate and deserves further analysis. The average birth weight with gestational age at 40 weeks was 3239 +/- 385 gm, skewness and kurtosis were 0.16 and 0.75, respectively. The birth-weight distribution for a given number of gestational weeks is closer to the normal distribution. This paper provides standard figures and tables of birth weight with specific gestational age as a norm for related medical research.

Birth Weight↗
PubMed1989

Structure of bovine milk lipoprotein lipase.

The primary structure of bovine milk lipoprotein lipase (bLPL) was determined by alignment of peptides produced by tryptic digestion, Staphylococcus aureus V8 protease digestion, and cyanogen bromide cleavage. bLPL consists of 450 amino acid residues. Most tryptic peptides were isolated and analyzed, except for the dipeptide, Glu-Lys (position 423-424), and the 2 Lys at positions 416 and 488. Peptides resulting from digestion by S. aureus V8 protease and cyanogen bromide cleavage filled the missing part and completed the primary sequence of bLPL. The NH2 terminus of bLPL was determined to be Asp by sequencing the intact protein with a gas phase sequencer for up to 30 residues, whereas the COOH terminus was identified as Gly through, carboxyl peptidase Y cleavage. The enzyme contains 10 cysteine residues, all of which exist in disulfide linkages. They are formed between Cys29 and Cys42, Cys218 and Cys241, Cys266 and Cys285, Cys277, and Cys280, and Cys420 and Cys440. The sites of N-glycosylation were identified at Asn44 and Asn361. In accordance with a common structural homology of serine-type esterases, -G-X-S-X-G- (Yang, C. Y., Manoogian, D., Pao, Q., Lee, F., Knapp, R. D., Gotto, A. M., Jr., and Pownall, H. J. (1987) J. Biol. Chem., 262, 3086-3191), the active site serine of bLPL was assigned to the serine at position 134. The chymotrypsin nick of bLPL was determined to be between residues 390 and 391. A model of the enzyme is proposed on the basis of our data and available chemical data.

Amino Acid Sequence↗
PubMed1989

The primary structure of human apolipoprotein A-IV.

Human apolipoprotein (apo) A-IV was purified from chylous ascites fluid. Proteolytic peptides produced by trypsin and Staphylococcus aureus V8 proteinase digestions were purified by high-performance liquid chromatography and sequenced. Human apoA-IV contains 376 amino acid residues. The peptide-derived sequence generally matches two previously reported DNA-derived amino acid sequences except for discrepancies in five positions. In order to examine these discrepancies further, one complete apoA-IV cDNA clone and another partial clone were sequenced. Comparison of all the available information indicates that the peptide-derived sequence reported here is accurate. Sequencing errors probably account for some of the discrepancies between the two primary sequences predicted by earlier nucleotide analyses. In certain positions, however, bona fide sequence heterogeneity or cloning artifact cannot be excluded.

Amino Acid Sequence↗
PubMed1989

Structure and conformational analysis of lipid-associating peptides of apolipoprotein B-100 produced by trypsinolysis.

Apolipoprotein B-100 (apo B-100) contains putative lipid-associating regions that are, in part, responsible for its overall structure in human plasma low-density lipoproteins. Some of these regions have been identified by reassembly of the total tryptic peptides of apo B-100 with bovine brain sphingomyelin, 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC) and dimyristoylphosphatidylcholine (DPMC). Although more than 500 tryptic peptides are predicted from the known number of arginines and lysines in apo B-100, significant amounts of only 13 peptides spontaneously associate with all three phospholipids. These peptides share some structural characteristics, as predicted by several algorithms, that distinguish them from the water-soluble apolipoproteins. Most apolipoproteins associate with lipids via amphipathic helices and are highly helical in native and reassembled lipoproteins. Analysis of all apo B-100 lipophilic peptides by circular dichroism and by use of a predictive algorithm reveals no evidence of amphipathic helices. Although the predictive algorithm suggested that the lipophilic peptides of apo B-100 contain the sequence determinants for beta-sheet, no spectroscopic evidence for this structure was found. We conclude that the lipophilic regions of apo B-100 liberated by trypsinolysis are highly hydrophobic, although their secondary structures do not fit any simple model.

Amino Acid Sequence↗
PubMed1989

Occurrence of Langerhans cells and expression of class II antigens on keratinocytes in malignant and benign epithelial tumors of the skin: an immunohistopathologic study with monoclonal antibodies.

We used an avidin-biotin complex immunoperoxidase technique with various monoclonal antibodies to determine Langerhans cell densities, class II antigen expression on keratinocytes, and phenotypes of other infiltrating cells in several malignant and benign epithelial tumors of the skin. Our observations indicate (1) there are few Langerhans cells in nests of basal cell carcinoma and squamous cell carcinoma; (2) there are increased Langerhans cell densities in seborrheic keratoses, verrucous epidermal nevus, and Bowen's disease; (3) there is an expression of class II molecules on the keratinocytes and cancer cells of basal cell carcinoma, squamous cell carcinoma, Bowen's disease, seborrheic keratosis, and verrucous epidermal nevus; and (4) there is a netlike staining of the keratinocyte surface with OKM5 in the epidermal lesion of seborrheic keratosis, verrucous epidermal nevus, and Bowen's disease, as well as in the epidermis adjacent to the basal cell carcinoma and squamous cell carcinoma nests.

Adolescent↗
PubMed1989

Enzyme-specific activities and mineral concentrations of the exocrine pancreas from female SHR/N-corpulent (cp) rats.

A new rodent model, SHR/N-cp, for study of non-insulin-dependent diabetes mellitus (NIDDM) has recently been developed. The present study reports exocrine pancreatic enzyme activities and mineral concentrations in female corpulent (cp/cp) and lean (+/?) rats fed a diet containing carbohydrate as cooked corn starch or sucrose for 7 months to determine the potential of the model for studies of diet and pancreatic function in NIDDM. Although corpulent female rats weighed 2.5 times more than their lean littermates, they consumed less calories when expressed per 100 g body weight than lean rats. Corpulent rats had a significantly smaller relative pancreatic weight than lean rats (p less than 0.0001), but had greater total pancreatic DNA content and concentration (p less than 0.003) and higher pancreatic amylase (p less than 0.0001), lipase (p less than 0.0011), and chymotrypsinogen (p less than 0.0208) specific activities. Corpulent rats had a significantly lower pancreatic copper concentration than their lean littermates (p less than 0.0193). Corpulent rats consuming starch had a higher pancreatic iron concentration than all other experimental groups (p less than 0.05). The corpulent female rats were only mildly diabetic based upon serum and urine indices. The data suggest that the female SHR/N-corpulent rat may be a useful model for studying exocrine pancreatic function of mild cases of non-insulin-dependent diabetes.

Amylases↗
PubMed1989

Maternal smoking in relation to the incidence of early neonatal jaundice.

A case-control study was carried out to investigate the association between maternal smoking during pregnancy and the risk of early neonatal jaundice. A total of 1,569 cases of neonatal jaundice (2.7% of all singleton births) were identified from the 1984 Washington State birth certificates as having a bilirubin level greater than 10 mg/dl within the first 2 days of life. 2,336 nonjaundiced infants were randomly selected to serve as controls. Information regarding smoking during pregnancy was also obtained from the birth certificates. After excluding infants with known risk factors for neonatal jaundice, 912 cases and 1,752 controls were available for analyses. Infants whose mother smoked cigarettes during pregnancy were at lower risk of neonatal jaundice (odds ratio = 0.81; 95% confidence interval = 0.66-0.99) relative to infants of nonsmokers. This relative risk changed very little after adjusting separately for maternal age, infant's gender, number of prior pregnancies, number of prenatal visits, marital status and number of prior fetal deaths. There was suggestive evidence that this apparent protective effect may be operating only among normal and high-birth-weight infants.

Adolescent↗