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Biomedical subjects

C L Yang

Publications and source records attributed to C L Yang.

At least 55 records · Page 3Linked to original sources
PubMed1994

Orally administered glycolipid derivative LIGA20 reduces infarct volume and behavioral impairment after focal cerebral ischemia.

The efficacy of p.o. semisynthetic glycolipid LIGA20 (II3Neu5-AcGgOse4-2-d-erythro-1,3-dihydroxy-2-dichloro-aceta mide-4-trans- octadecene) treatment in stroke was studied in a permanent left middle cerebral artery occlusion model in the rat. A dose-dependent increase of plasma LIGA20 and its presence in the brain were documented after p.o. drug application. Oral administration of 50 to 200 mg/kg of LIGA20, initiated 24 hr before middle cerebral artery occlusion and continued for 7 days, reduced the motor and cognitive impairment after the stroke, measured by the rotarod and the passive avoidance test, respectively. The 10-mg/kg dose was effective when given i.v. but not p.o. Oral treatment with 100 mg/kg of LIGA20 reduced the infarct size in the cortex but not in the ischemic core (the striatum). No biochemical or behavioral adverse effects of LIGA20 treatment were observed. Further studies are needed to evaluate the full therapeutic potential of this compound.

Administration, Oral↗
PubMed1993

Collagen II from articular cartilage and annulus fibrosus. Structural and functional implication of tissue specific posttranslational modifications of collagen molecules.

Collagen II was isolated and characterized from hyaline cartilage (articular cartilage) and fibro-cartilage (annulus fibrosus). Collagen II from the latter tissue has a substantially higher degree of hydroxylation and glycosylation than that isolated from articular cartilage. The higher degree of posttranslational modification was associated with a slower electrophoretic mobility, a greater resistance to mammalian collagenase digestion and a higher thermal stability. An increase of glycosylation accelerates the initial steps in fibril formation of collagen molecules but slows down the following lateral growth. The newly formed aggregates of collagen II from annulus fibrosus consisted of fibrils with a smaller diameter.

Amino Acid Sequence↗
PubMed1993

Autoantibodies to cartilage collagens in relapsing polychondritis.

Relapsing polychondritis is a systemic disease associated with a destruction of cartilage in various parts of the body. Sera from six patients with relapsing polychondritis and one patient with microscopic polyarteritis nodosa as well as from six controls were analyzed by immunoblotting and ELISA. All patients had autoantibodies against native collagens II and IX. The serum from one patient showed a strong reaction with all three collagen chains of the high molecular weight fraction of collagen IX after denaturation; sera from four patients showed autoantibodies against alpha 2 (XI) and sera from three patients showed autoantibodies against the covalently cross-linked gamma component of collagen XI. The presence of autoantibodies against collagens II, IX, and XI, which form the major fibrillar scaffold in cartilage and mediate the interaction of collagen fibrils and proteoglycan, suggests that autoantibodies against cartilaginous collagen may play a crucial role in the pathogenesis of relapsing polychondritis and microscopic polyarteritis nodosa.

Adult↗
PubMed1993

DNA sequence polymorphism of the Chlamydia trachomatis omp1 gene.

The Chlamydia trachomatis major outer membrane protein gene (omp1) was amplified by polymerase chain reaction (PCR) from 89 clinical specimens, and restriction fragment length polymorphism (RFLP) patterns were analyzed after AluI or AluI and MspI digestion. Ten distinct RFLP omp1 genotypes were observed, although 4 types accounted for 70% of the isolates. The DNA sequence of variable domains (VDs) 1, 2, and 4 were determined for 49 samples. Thirty samples (61%) had prototype VD sequences, 15 (31%) had sequences that varied from prototype sequences, and 4 (8%) contained sequences from > 1 chlamydial isolates. Eleven of the 15 DNA sequence variations were one- or two-site nucleotide substitutions, 10 of which resulted in an amino acid change. Four DNA sequence variations were more extensive, with multiple nucleotide substitutions, insertions, or deletions. The data demonstrate that C. trachomatis isolates circulating in a relatively circumscribed geographic community exhibit remarkable omp1 DNA sequence polymorphism.

Amino Acid Sequence↗
PubMed1993

Submicrostructure and typing of female genital condylomata.

Thirty biopsies from female genital condylomata were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to study structural characteristics and typing of condylomata. It was found that cytoplasmic clearing was marked in acuminate condylomata, diffuse interstitial and epithelial proliferation in nodular condylomata (flat condylomata), and invagination of the lesions into the interstitial tissue or glandular ducts in endophytic condylomata. In nodular condylomata, SEM also showed some structural features similar to those of intra-epithelial neoplasia. Microridges on the surface of squamous cells had villiform of granular changes. On the surface of a percentage of squamous or columnar cells, there were holes with a diameter of about 3 to 5 microns. A number of giant cells were seen among other cells. The cervical squamatization zone contained groups of special cells covered with dense microvilli. TEM of nodular condylomata revealed some pictures resembling active proliferation of tumor cells, such as enlarged or irregular nuclei (large N/C ratio), evaginated or invaginated nuclear membranes, condensed chromatin attached to the inner part of the nuclear membrane, transparent nucleoplasm, and frequent nucleosomes and karyokinesis. Virus particles with the morphological characteristics of HPV (naked hexagon-like particles with an average diameter of 45-50 nm) were seen in some nuclei with markedly condensed chromatin. It is suggested that HPV-induced genital condylomata, especially nodular one (flat condylomata), entail a potential progression to malignancy.

Adult↗
PubMed1992

Molecular cloning of the cDNA for the catalytic subunit of human DNA polymerase delta.

The cDNA of human DNA polymerase delta was cloned. The cDNA had a length of 3.5 kb and encoded a protein of 1107 amino acid residues with a calculated molecular mass of 124 kDa. Northern blot analysis showed that the cDNA hybridized to a mRNA of 3.4 kb. Monoclonal and polyclonal antibodies to the C-terminal 20 residues specifically immunoblotted the human pol delta catalytic polypeptide. A multiple sequence alignment was constructed. This showed that human pol delta is closely related to yeast pol delta and the herpes virus DNA polymerases. The levels of pol delta message were found to be induced concomitantly with DNA pol delta activity and DNA synthesis in serum restimulated proliferating IMR90 cultured cells. The human pol delta gene was localized to chromosome 19 by Southern blotting of EcoRI digested DNA from a panel of rodent/human cell hybrids.

Amino Acid Sequence↗
PubMed1992

Identification of highly conserved and species-specific polypeptides of Haemophilus ducreyi.

Chancroid is a sexually transmitted diseased caused by Haemophilus ducreyi. The pathological manifestations of chancroid are unique among Haemophilus species and the virulence factors of H. ducreyi that account for these features have not been identified. Some of these virulence factors may be unique components of H. ducreyi, but attempts to identify H. ducreyi-specific components have been unsuccessful. Four polypeptides--A, B, C and D of 83, 77, 56 and 28 kDa, respectively--were identified with a panel of nine H. ducreyi-specific monoclonal antibodies (MAbs). Polypeptide C was one of the five major proteins in H. ducreyi and demonstrated micro-heterogeneity in SDS-PAGE. Polypeptides A, B and D were present in only small amounts in whole-cell lysates of H. ducreyi. The relative amounts of A and B varied, suggesting that they may be precursor molecules. The unique polypeptides C and D were not exposed on the surface. Polypeptide C was highly soluble and did not appear to be membrane-bound, whereas polypeptide D appeared to partition with the cytoplasmic membrane and was soluble in Sarkosyl. All four polypeptides appeared to be unique to H. ducreyi since MAbs directed against them did not cross-react with H. influenzae, H. parainfluenzae or Neisseria gonorrhoeae. The mol. wts of all of these polypeptides were conserved throughout 35 clinical isolates collected from 15 cities in eight countries and one reference strain of H. ducreyi that were tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1992

High-level expression of the rat whey acidic protein gene is mediated by elements in the promoter and 3' untranslated region.

The high-level expression of the rat whey acidic protein (WAP) gene in transgenic mice depends on the interaction of 5'-flanking promoter sequences and intragenic sequences. Constructs containing 949 bp of promoter sequences and only 70 bp of 3'-flanking DNA were expressed at uniformly high levels, comparable to or higher than that of the endogenous gene. Although this WAP transgene was developmentally regulated, it was expressed earlier during pregnancy than was the endogenous WAP gene. Replacement of 3' sequences, including the WAP poly(A) addition site, with simian virus 40 late poly(A) sequences resulted in an approximately 20-fold reduction in the expression of WAP mRNA in the mammary gland during lactation. Nevertheless, position-independent expression of the transgene was still observed. Further deletion of 91 bp of conserved WAP 3' untranslated region (UTR) led to integration site-dependent expression. Position independence was restored following reinsertion of the WAP 3' UTR into the deleted construct at the same location, but only when the insertion was in the sense orientation. The marked differences observed between the expression levels of the 3'-end deletion constructs in transgenic mice were not seen in transfected CID 9 mammary epithelial cells. In these cells, expression of the endogenous WAP gene was dependent on the interaction of these cells with a complex extracellular matrix. In contrast, the transfected WAP constructs were not dependent on extracellular matrix for expression. Thus, both the abnormal expression of WAP in cells cultured on plastic and the precocious developmental expression of WAP in transgenic mice may reflect the absence of a negative control element(s) within these recombinant constructs.

Animals↗
PubMed1992

Topical application of local anesthetics for postoperative analgesia in children undergoing circumcision.

Circumcision often followed by severe pain during the postoperative period. Forty boys, ASA class I, presenting for day case circumcision were allocated randomly to receive either 4% prilocaine hydrochloride spray or 1.1% dipucaine ointment at the end of the operation. Analgesia was assessed by a single observer utilizing a three-point scale in recovery room. The parents were asked to complete the questionnaire 8h following operation and on the morning of the first postoperative day. At approximately 24h following operation an assessment of the child's activity level was made by the parents. The frequency of taking the oral analgesia was also recorded. Both topical analgesics provided satisfied analgesia during the postoperative period and no complication was noted. Only one patient in dipucaine group vomited in the recovery room. We conclude that topical use of prilocaine hydrochloride and dipucaine can provide a simple, safe and adequate analgesia for post-circumcision pain relief.

Administration, Topical↗
PubMed1991

Fulvic acid disturbs processing of procollagen II in articular cartilage of embryonic chicken and may also cause Kashin-Beck disease.

Kashin-Beck disease is an endemic osteoarthropathy in China which may lead to skeletal deformation and dwarfism. We have analysed articular cartilage from two patients and found an accumulation of the precursor molecule, pro-pN-collagen II (pN, peptide attached at the amino-terminus) which was not present in extracts of control fetal cartilage. In addition, collagen II isolated from the same tissue by limited pepsin digestion had a decreased electrophoretic mobility, increased proline hydroxylation and decreased thermal stability. Previously, a genetic defect in pro-pN-collagen-I processing has been described in calf and sheep (dermatosparaxis) and man (Ehlers-Danlos, type VII) which caused an extreme fragility of the skin [Lenaers, A., Ansay, M., Nusgens, B.V. & Lapière, C.M. (1971) Eur. J. Biochem. 23, 533-541; Helle, O. & Nes, N.J. (1972) Acta Vet. Scand. 13, 443-445; Lichtenstein, J.R., Martin, G.R., Kohn, L.D., Byers, P.H. & McKusick, V.A. (1973) Science 182, 298-300]. Accordingly, one may assume that the impaired conversion of pro-pN-collagen II to collagen II and the structural alteration of collagen II, presumably caused by fulvic acid and other environmental factors, play an important role in the pathogenesis of Kashin-Beck disease.

Adult↗
PubMed1991

Induction of DNA polymerase activities in the regenerating rat liver.

The levels of DNA polymerase alpha, DNA polymerase delta, and its accessory protein, proliferating cell nuclear antigen (PCNA) were examined in the regenerating rat liver. The levels of DNA polymerase alpha and delta activities in regenerating liver extracts were determined by the use of the DNA polymerase alpha specific inhibitor, BuAdATP [2-(p-n-butylanilino)-9-(2-deoxy-beta-D-ribofuranosyl) adenine 5'-triphosphate], and monoclonal antibodies. These reagents showed that the total DNA polymerase activities increased ca. 4-fold during regeneration and that the fraction of DNA polymerase delta activity at the peak was 40% of the total DNA polymerase activity. Immunoblots and inhibition studies using specific antibodies showed that DNA polymerase delta and epsilon and PCNA were concomitantly induced after partial hepatectomy. The levels of both DNA polymerase delta and epsilon and PCNA reached their maxima at 24-36 h post hepatectomy, i.e., at the same time that in vivo DNA synthesis reached its peak. Partial purification and characterization of DNA polymerases delta and epsilon from the regenerating rat liver were also performed. These observations suggest that the variation of DNA polymerase delta and epsilon and PCNA during liver regeneration is closely related to DNA synthesis and is consistent with their involvement in DNA replication.

Adenosine Triphosphate↗
PubMed1991

Examination of the roles of selenium in the Kaschin-Beck disease. Cartilage cell test and model studies.

The Kaschin-Beck Disease, an endemic disease in China, occurs in low-selenium areas. Using human embryonic cartilage cell as a system, the effect of selenite and another etiological factors, such as, organic matters in water, and grain from disease regions, were studied. It was shown that Se(IV), as well as superoxide dismutase, could prevent the cells from damage by organic matters, and increase the activity of GSHpx and decrease the production of lipid peroxide. A model test of adrenalin autooxidation was carried out, and it was found that the oxy-radical can be eliminated by Se(IV). Thus, it was assumed, that selenium was a protective factor and free radical scavenger for Kaschin-Beck Disease.

Benzopyrans↗
PubMed1991

Structural comparison of the Autographa californica nuclear polyhedrosis virus-induced RNA polymerase and the three nuclear RNA polymerases from the host, Spodoptera frugiperda.

A partial subunit structure has been determined for the novel RNA polymerase that is induced in fall armyworm (Spodoptera frugiperda) cells upon infection with the Autographa californica nuclear polyhedrosis virus (AcNPV). The putative structure includes nine polypeptides; the complexity of this structure is in accord with the high sedimentation coefficient (15S) estimated for this enzyme. A comparison of the putative structure of the virus-induced polymerase with those of the three host nuclear RNA polymerases shows that the structure of the viral polymerase is apparently unlike any of the host nuclear polymerases. This conclusion is reinforced by immunoblot experiments that show no cross-reactivity between the virus-induced polymerase and an antiserum directed against Drosophila RNA polymerase II. The virus-induced RNA polymerase appears at the onset of the late phase of infection and still appears when viral DNA synthesis is blocked by aphidicolin. Thus, the virus-induced polymerase seems to be composed of early viral products.

Animals↗
PubMed1991

Protective effect of zinc-induced metallothionein synthesis on gentamicin nephrotoxicity in rats.

Wistar rats were used to study the protective effect of zinc-induced metallothionein (MT) synthesis on gentamicin nephrotoxicity. We found that s.c. pre-injection of ZnSO4 (Zn 10 mg/kg/day) for 5 days could ameliorate proximal tubular necrosis and acute renal failure caused by an 8-day s.c. injection of gentamicin (100 mg/kg/day), while preinjection of saline instead of zinc or zinc and gentamicin together could not. In the zinc-pretreated rats (n = 6), renal cortical metallothionein level was significantly higher than that of normal (n = 8, p less than 0.001) and the saline controls (n = 6, p less than 0.001). Since MT is a scavenger of hydroxyl radical, it is proposed that hydroxyl radical plays a role in the pathogenesis of gentamicin nephrotoxicity and that preinjection of zinc could ameliorate gentamicin nephrotoxicity via the induction of renal cortical MT synthesis.

Acute Kidney Injury↗
PubMed1991

[Surgical and anesthetic mortality in Mackay Memorial Hospital 1988-1989].

The mortality associated with 52128 anesthetics administered over two years (1988-1989) at Mackay Memorial Hospital, Taipei, was reported. The frequency of death to which anesthesia contributed was 0.4/10000 (2 cases in 52128 anesthetics). The total mortality rate from surgery within one week was 0.2% (105 cases in 52128 anesthetics). Anesthetic deaths were responsible for 1.9% of the total mortality. There were 25 cases of cardiac arrest with 18 fatal cases (7 cases were recovered after cardiopulmonary resuscitation). The causes of cardiac arrest during anesthesia included anesthetic factors (24%), surgical factors (24%) and patients' pathological factors (52%).

Anesthesia↗
PubMed1990

A comparison of newly and previously diagnosed diabetics in Taiwan.

Between 1985 and 1986, during a population survey of diabetes in 1 urban and 5 rural areas of Taiwan, a total of 11,478 adults aged 40 or older were screened. Capillary whole blood glucose was determined with a glucometer (Ames Co.) The diabetic criteria followed the WHO designations. From this survey, a comparison of 225 newly diagnosed and 383 previously diagnosed diabetics was conducted. Multiple regression analysis revealed a highly significant correlation for all diabetics with regard to age, body mass index, family history and hypertension, but no specific correlation to habitat. Mean fasting glucose levels in previously and newly diagnosed diabetics were 172 and 158 (males 158 vs 147 and females 184 vs 165) mg/dl, respectively, which suggest that treatment is apparently inadequate in this population. The prevalent rate (%) of retinopathy for previously and newly diagnosed diabetics was 45.2 and 28.3 (males 42.8 vs 33.3 and females 47.5 vs 24.8), respectively. The prevalence is as common as those reported in western countries. In conclusion, previously diagnosed diabetics had higher fasting glucose concentrations and prevalent rates of retinopathy than newly diagnosed diabetics, and these findings were particularly prominent in females.

Adult↗
PubMed1989

Specific chromosome changes and nonoccupational exposure to potentially carcinogenic agents in acute leukemia in China.

Cytogenetic studies were performed on 44 Chinese patients with acute leukemia. A high percentage of patients (37.5%) with t(8;21), t(15;17) or 17q- (in poorly banded preparations), and abnormalities involving 11q23 were noted in 32 unselected patients with ANLL. A similar high percentage was previously reported in Japan and in South Africa but not in western countries. Data on casual or other non-occupational exposure to potentially carcinogenic agents were obtained by interview with the patients at their first presentation. Most patients with these three major chromosomal changes had a history of exposure, whereas most other patients did not (p = 0.01). Patients with ANLL-M3 were more often exposed than were the other patients (4/6 vs 8/38, p = 0.03). The only common exposure was to organophosphate insecticides. Twenty seven cases of therapy-related leukemia were collected from the Chinese medical literature, and 12 out of 22 (55%) cases in which subtypes were specified were ANLL-M3. This was significantly higher than the percentage of M3 in de novo ANLL in China and also higher than that of therapy-related leukemia from western countries. Two patients had siblings who died of leukemia at a similar age. The two patients showed inv(16) and del(6q) respectively.

Acute Disease↗