Biomedical subjects

C S Chung

Publications and source records attributed to C S Chung.

At least 73 records · Page 4Linked to original sources

PubMed1997

Surgery and gastrointestinal bleeding.

Therapeutic endoscopy has become the first line treatment for acute ulcer bleeding. Because of this, and the discovery that most ulcers are caused by Helicobacter pylori, the indications for operating intervention and the choice of operation for acute ulcer bleeding need not be reconsidered. surgery is indicated for patients if bleeding is not controlled by endoscopic means, or if rebleeding occurs after endoscopic haemostasis. The most expedient operation that can secure permanent control of bleeding should be chosen. For small ulcers, undersewing or excision of the ulcer is adequate. For larger ulcers a technically difficult gastrectomy is often required to secure haemostasis.

Endoscopy↗

PubMed1996

The unique endometrial expression and genomic organization of the porcine IGFBP-2 gene.

The insulin-like growth factor-binding proteins (IGFBPs-1-6) modulate the mitogenic and differentiative actions of the IGFs and may have IGF-independent functions. This study examined the gene expression and pregnancy-regulation of the IGF/IGFBP system in porcine uterine endometrium and myometrium during the periimplantation period and later stages of pregnancy. Endometrial IGFBP-2 mRNA abundance exhibited stage of pregnancy-dependent induction; whereas little or no IGFBP-2 mRNA was found in myometrium. IGFBP-2 protein was immunolocalized to the endometrial glandular and luminal epithelia (staining on day 60 > day 12) with minimal or no immunostaining of uterine stroma observed. IGFBP-3 and IGFBP-4 transcript levels became elevated in endometrium after implantation; whereas, IGFBP-5 and IGFBP-6 mRNAs were in greater abundance in periimplantation than post-implantation endometrium. IGFBP-1 transcripts, in contrast, could not be identified in porcine endometrium or myometrium of pregnancy. As a pre-requisite to understanding the pregnancy-induction and endometrial-specificity of the uterine-expressed IGFBP-2 gene, cosmids encompassing the pig IGFBP-2 chromosomal locus were isolated and characterized. This gene is comprised of four exons that span > 29 kb and encode a 316 amino acid precursor protein. All four exons were found to be G/C rich with exon 1 and immediate 5' flank exhibiting hallmarks of a CpG island. This latter region was devoid of TATA and CAAT motifs. Results identify the preferential endometrial expression of different IGFBP genes at either the periimplantation or post-implantation periods, perhaps reflecting distinct actions of these proteins at the embryo-maternal and feto-maternal interfaces, respectively. Interactions of steroid receptors, endometrial transcription factors and their corresponding cis elements may confer the unique uterine expression of the IGFBP-2 gene.

Amino Acid Sequence↗

PubMed1996

Thalamic haemorrhage.

Thalamic haemorrhage is usually considered a single entity although the thalamus is composed of anatomically as well as functionally discrete subregions receiving blood from different arteries. The clinical features vary according to the intrathalamic location of the haematomas and the bleeding artery. We investigated the impact of haematoma location and vascular territory on the clinical symptoms and signs, neuro-imaging findings and clinical courses of patients with thalamic haemorrhages by a retrospective analysis of 175 consecutive patients with thalamic haemorrhage. Based on the neuro-imaging findings we classified thalamic haematomas into four regional types and one global type according to the primary bleeding sites: (i) anterior type occurring in the territory of the tuberothalamic arteries, (ii) posteromedial type occurring in the territory of the thalamic-subthalamic paramedian arteries, (iii) posterolateral type occurring in the territory of the thalamogeniculate arteries. (iv) dorsal type occurring in the territory of the posterior choroidal arteries and (v) global type occupying the entire area of the thalamus. We studied the clinical and neuroimaging characteristics of each type. Eleven patients (7%) had the anterior type: these were the smallest haematomas and often ruptured into the anterior horn of the lateral ventricle. The major clinical signs were acute behavioural abnormalities: the clinical course was usually benign. Twenty-four patients (14%) had the posteromedial type in which haematomas often ruptured into the third ventricle, causing marked hydrocephalus, and often extended mediocaudally, involving the mesencephalon. The prognoses of this type depended on the presence of mesencephalic involvement which was associated with the worst outcome among the types even if the size of the haematoma itself was not large. The posterolateral type was most frequent (77 patients, 44%) and was characterized by large haematomas, rupture into the posterior horn of the lateral ventricle and frequent extension into the posterior limb of the internal capsule. Clinical signs included marked sensory and motor signs, hemineglect in right-side haematomas and language abnormalities with left-side haematomas. The case fatality with this type was relatively high (35%) and permanent neurologic sequelae frequently resulted. In the dorsal type (32 patients, 18%) haematomas were best visualized at the level of the body of the lateral ventricle on CT scans. The size was moderate and haematomas often extended posterolaterally into the adjacent subcortical white matter. Sensory and motor signs were common and about one third of the patients were first misdiagnosed as having lacunar infarcts. The prognoses were excellent. The global type (31 patients, 18%) of thalamic haemorrhage was clinically and radiologically very similar to the posterolateral type except that the haematomas were too large to define the bleeding focus. Severe sensory and motor signs were almost always present. In this type 25 patients died (the case fatality was 81%).

Adolescent↗

PubMed1996

Isolation and characterization of a Chinese hamster ovary mutant cell line with altered sensitivity to vaccinia virus killing.

The Chinese hamster ovary (CHO) cell line is nonpermissive for vaccinia virus, and translation of viral intermediate genes was reported to be blocked (A. Ramsey-Ewing and B. Moss, Virology 206:984-993, 1995). However, cells are readily killed by vaccinia virus. A vaccinia virus-resistant CHO mutant, VV5-4, was isolated by retroviral insertional mutagenesis. Parental CHO cells, upon infection with vaccinia virus, die within 2 to 3 days, whereas VV5-4 cells preferentially survive this cytotoxic effect. The survival phenotype of VV5-4 is partial and in inverse correlation with the multiplicity of infection used. In addition, viral infection fails to shut off host protein synthesis in VV5-4. VV5-4 was used to study the relationship of progression of the virus life cycle and cell fate. We found that in parental CHO cells, vaccinia virus proceeds through expression of viral early genes, uncoating, viral DNA replication, and expression of intermediate and late promoters. In contrast, we detect only expression of early genes and uncoating in VV5-4 cells, whereas viral DNA replication appears to be blocked. Consistent with the cascade regulation model of viral gene expression, we detect little intermediate- and late-gene expression in VV5-4 cells. Since vaccinia virus is known to be cytolytic, isolation of this mutant therefore demonstrates a new mode of the cellular microenvironment that affects progression of the virus life cycle, resulting in a different cell fate. This process appears to be mediated by a general mechanism, since VV5-4 is also resistant to Shope fibroma virus and myxoma virus killing. On the other hand, VV5-4 remains sensitive to cowpox virus killing. To examine the mechanism of VV5-4 survival, we investigated whether apoptosis is involved. DNA laddering and staining of apoptotic nuclei with Hoechst 33258 were observed in both CHO and VV5-4 cells infected with vaccinia virus. We concluded that the cellular pathway, which blocks viral DNA replication and allows VV5-4 to survive, is independent of apoptosis. This mutant also provides evidence that an inductive signal for apoptosis upon vaccinia virus infection occurs prior to viral DNA replication.

Animals↗

PubMed1996

Cerebellar hemorrhagic infarction.

We investigated 17 patients with 26 cerebellar hemorrhagic infarcts for their vascular anatomy, stroke mechanisms, and clinical course. Sixteen infarcts involved the superior cerebellar artery, nine the posterior inferior cerebellar artery, and one the anterior inferior cerebellar artery territories. The infarcts involved the full territory of the supplying arteries in 19 of 26 infarcts (73%). Sixteen of 17 patients were stable or improving when the hemorrhagic infarction was detected. All but one patient had an imaging study at the time of presentation that was negative for blood; hemorrhagic infarction was detected on routine serial scans performed during the first 15 days. Nine of the 17 patients were on anticoagulants when the cerebellar hemorrhagic infarct was detected; anticoagulation was maintained in eight of them with no clinical worsening. The stroke mechanism in all patients was considered embolic from cardiac and intra-arterial sources. The causes, imaging findings, and consequences of hemorrhagic infarcts in the posterior circulation are similar to those in the anterior circulation.

Anticoagulants↗

PubMed1995

Isolation of a monoclonal antibody which blocks vaccinia virus infection.

We have isolated a monoclonal antibody, B2, that neutralizes vaccinia virus infection. B2 reacts with a trypsin-sensitive cell surface epitope. B2 does not neutralize infection of herpes simplex virus, suggesting that the B2-reactive epitope is specifically involved in vaccinia virus entry. A survey of 12 different cell lines reveals a correlation between B2 reactivity and susceptibility to vaccinia virus infection. In addition, B2 interferes with vaccinia virus adsorption to target cells. Taken together, the B2-reactive epitope is part of a receptor that appears important for vaccinia virus entry.

Animals↗

PubMed1995

Medial medullary syndrome. Report of 18 new patients and a review of the literature.

BACKGROUND AND PURPOSE: With advanced imaging techniques, infarctions occurring in the medulla are now more easily identified. To date, however, only approximately 30 cases of medial medullary infarction syndrome (MMS) have been reported, and the clinical and radiological characteristics of MMS remain to be studied. METHODS: We studied 18 patients (15 men, 3 women; mean age, 62 years) who had compatible clinical and MRI findings of MMS and reviewed the previously reported cases. RESULTS: Seventeen patients had a unilateral lesion usually involving the upper medulla, and 1 had bilateral lesions. Fifteen patients had unilateral sensorimotor stroke, while 2 presented with pure motor stroke. The face was usually but not always spared. The degree of hemiparesis varied, and a tingling sensation with decreased vibration and position sense was the most common sensory manifestation. Two patients had lingual paresis, and none suffered respiratory difficulties. One patient presented with bilateral gait ataxia without sensorimotor dysfunction. Angiography or MR angiography performed in 9 patients showed vertebral artery disease in 6. Three patients had concurrent lateral medullary infarction, and 1 had a previous history of lateral medullary syndrome. The prognosis was generally good, although residual hemiparesis remained in patients with initially severe hemiparesis. Review of 26 previously reported cases showed that they frequently had bilateral lesions, often presenting with quadriplegia, lingual paresis, respiratory symptoms, and a grave prognosis. CONCLUSIONS: Our data illustrate that MMS is most often manifested as benign hemisensorimotor stroke frequently associated with tingling sensation and impaired deep sensation. This benign form of MMS should be much more common than MMS with poor prognosis and may have been frequently misdiagnosed as capsular or pontine stroke before the era of MRI.

Adult↗

PubMed1994

Monoclonal antibodies that distinguish between encephalitogenic bovine herpesvirus type 1.3 and respiratory bovine herpesvirus type 1.1.

Seven mouse hybridoma cell lines producing monoclonal antibodies (MAb) against an encephalitogenic strain of bovine herpesvirus type 1.3 (BHV-1.3) were established. The clones producing MAb were selected to be specific for BHV-1.3 by enzyme-linked immunosorbent assay. Only L1B neutralized virus without complement. With the addition of complement, five of the MAb neutralized BHV-1.3 but not the respiratory strain BHV-1.1. The anti-BHV-1.3-specific MAb Q10B, L6G, and L1B precipitated glycoproteins from BHV-1.3 that were analogous to the gI, GIII, and gIV glycoproteins of BHV-1.1, respectively. The other four MAb precipitated unknown proteins. None of the anti-BHV-1.3 MAb precipitated BHV-1.1 glycoproteins. The majority of the anti-BHV-1.3 MAb did not react with BHV-1.1 by immunoblotting, but O7E (unknown protein pattern by radioimmunoprecipitation) was reactive with five proteins (M(r)s of 33,000, 43,000, 70,000, 141,000, and 190,000) of BHV-1.3 and with a different pattern of proteins of BHV-1.1 (M(r)s of 30,000, 38,000, 83,000 and 144,000). Two of the MAb, L6G and O7E, conjugated with peroxidase were found to be useful for detecting BHV-1.3 antigen by immunochemistry in Formalin-fixed brain tissue from experimentally infected calves.

Animals↗

PubMed1994

Cerebellar infarcts in the New England Medical Center Posterior Circulation Stroke Registry.

We report the clinical findings and stroke mechanisms of 63 patients with cerebellar infarcts. We divided the intracranial vertebrobasilar circulation into the proximal territory (P), fed by the intracranial vertebral arteries and their branches; the middle territory (M), fed by the proximal and middle basilar artery and its branches; and the distal territory (D), fed by the rostral basilar artery and its branches. Cerebellar infarcts were classified by vascular territories P, M, D, P&D, and middle-plus (P&M, M&D, and P&M&D). Patients with P infarcts (11 patients) frequently had vertigo, gait instability, limb ataxia, and headache, whereas patients with D infarcts (15 patients) most often had limb ataxia, gait instability, and dysarthria. Patients with P&D infarcts (17 patients) had signs and symptoms of both groups combined. Infarcts in which the middle territory was involved, either alone (three patients) or combined with other territories (17 patients) were dominated by brainstem signs and symptoms. The predominant stroke mechanisms in the P, D, and P&D groups were embolic due to intra-arterial or cardiac embolism. When the M territory was involved, either alone or with P, D, or P&D territories, stroke mechanisms were more varied, and there was often large-artery occlusion with hemodynamic ischemia.

Adult↗

PubMed1993

Ontogeny of the porcine insulin-like growth factor system.

The developmental expression of the individual components of the insulin-like growth factor (IGF) system in pigs was examined. Serum IGF-I and IGF-binding protein-3 (IGFBP-3) levels were low during fetal life and increased during postnatal development. Levels of mRNAs encoding these proteins were not greater for liver than for nonhepatic tissues (skeletal muscle, lung, kidney) and did not increase during the postnatal period, whereas hepatic growth hormone (GH) receptor mRNA expression was increased postnatally. Serum IGF-II levels exceeded IGF-I levels at all developmental stages examined and both exhibited postnatal increases. IGF-II mRNA abundance, in contrast, was high in the fetal tissues with the exception of lung and declined during the perinatal transition. Hepatic IGFBP-2 mRNA and serum IGFBP-2 levels increased during the latter half of gestation and then declined postnatally. The levels in muscle and liver of type I IGF receptors and the corresponding mRNAs also exhibited postnatal decreases. The discordance of changes in hepatic IGF-I and IGF-II mRNA abundance with serum IGF levels during the postnatal period does not support the concept that liver is the primary endocrine source of IGFs in the young pig. The postnatal increases in serum IGF levels may reflect decreased plasma clearance rates of these peptides which may be related to the transition in IGFBP type from IGFBP-2 to IGFBP-3 in blood and the reduced tissue expression of IGF receptors.

Animals↗

PubMed1993

The prevalence study on restriction fragment length polymorphism analysis for the detection of hemophilia A carrier.

We have analyzed two (BclI and XbaI) intragenic restriction fragment length polymorphisms (RFLPs) and St14 (DXS52) variable number of tandem repeats (VNTR) by rapid PCR method in 97 unrelated normal subjects. The incidences for positive Bc1I and XbaI polymorphic sites in the Koreans were 81% and 72%, respectively, which were higher than other ethnic groups but similar to that reported in the Chinese or Japanese, giving the heterozygosity rate of 0.32 and 0.40, respectively. The amplified allele size was 880 bp with no other polymorphism in the analysis of St14 (DXS52) VNTR. This finding should be taken into account in the planning of a prenatal diagnosis program for ethnic Koreans.

Base Sequence↗

PubMed1992

Isolation and characterization of nuclear proteins that bind to T cell receptor V beta decamer motif.

TCR V beta promoter contains a highly conserved decamer homologous to cAMP response element (CRE). Recent studies have identified this CRE decamer as the dominant transcription-activating element within the TCR V beta promoter. We have isolated cDNA clones, TCR-ATF1 and TCR-ATF2, encoding DNA-binding proteins that recognize this CRE motif. The nucleotide sequence of TCR-ATF1 has not previously been reported, whereas that of TCR-ATF2 was homologous to CRE-BP1, ATF-2, and mXBP. Both TCR-ATF1 and TCR-ATF2 shared a conserved leucine zipper and DNA binding motif with other CRE-binding proteins. TCR-ATF1 and TCR-ATF2 were expressed in all cell lines examined and in mouse embryos as early as 12.5 days. Despite binding to the same CRE motif, TCR-ATF1 and TCR-ATF2 were different from CREB in the fine nucleotide specificity. TCR-ATF bound methylated CRE and CRE mutant M4 (4C----G) that were not recognized by CREB. Additionally, TCR-ATF1 weakly recognized two other single nucleotide mutants of V beta-CRE that were not bound by TCR-ATF2 and CREB. We have further demonstrated that TCR beta-chain expression was immediately activated by cAMP. Such induction is likely mediated through V beta-CRE sequence, because the inclusion of V beta-CRE in a vector with minimum promoter (pBLCAT2) conferred the cAMP inducibility of CAT activity.

Amino Acid Sequence↗

PubMed1992

Primary pontine hemorrhage: a new CT classification.

The prognosis of primary pontine hemorrhage depends on the size, location, and extent of the hematoma. We investigated the relationship between CT features and prognosis in 61 consecutive cases. The CT features were classified into four types: basal-tegmental (23 cases), bilateral tegmental (7), massive (14), and small unilateral tegmental (17). Case survival rate was 94.1% for the small unilateral tegmental type, 26.1% for the basal-tegmental type, 14.3% for the bilateral tegmental type, and 7.1% for the massive type.

Adolescent↗

PubMed1992

Trends in prevalences of behavioral risk factors: recent Hawaiian experience.

Recent time trends were studied for the prevalences of behavioral risk factors in Hawaii during the 5-year period from 1986 through 1990. The presence of linear time trend was analyzed by the multiple logistic regression method on weighted data, adjusting for confounding factors. The risk factors studied were seatbelt nonuse, lack of exercise, obesity, hypertension, smoking, acute drinking, chronic drinking, and driving while intoxicated. Seatbelt nonuse showed a significant decline, from 8.6% to 4.8%, with a mean annual decrease of 0.9 percentage point. Lack of exercise and obesity increased steadily, from 48.0% to 62.4% and from 16.7% to 21.6%, respectively, with respective annual mean increases of 3.3 and 1.4 percentage points.

Chronic Disease↗

PubMed1991

Asia-Pacific prevention research. CHallenges, opportunities, and implementation.

An effort is underway in the Asia-Pacific region to carry out multidisciplinary prevention research, with an emphasis on understanding health-related behaviors. In partnerships with the U.S. Centers for Disease Control, the U.S. Public Health Service, international health agencies, governments, and universities in the region, researchers at the University of Hawaii are pursuing a paradigm for international, multicultural prevention research in the field of health promotion and disease prevention. An integrated framework for guiding a program of research is discussed along with several factors that present challenges to the conduct of prevention research in the Asia-Pacific region.

Developing Countries↗

PubMed1991

Epitope analysis of capsid and matrix proteins of North American ovine lentivirus field isolates.

Monoclonal antibodies (MAbs) directed against two phenotypically distinct ovine lentivirus (OvLV) strains were generated by fusion of BALB/c SP2/0-Ag 14 myeloma cells with spleen cells from mice immunized with purified OvLV. Hybridomas were selected by indirect enzyme-linked immunosorbent assay (ELISA) and analysis of reactivity on immunoblots. The majority (17 of 21) of the MAbs recognized the gag-encoded capsid protein, CA p27, of both strains. Four other MAbs recognized a smaller structural protein, presumably a matrix protein, MA p17. Three distinct epitopes on CA p27 and one on MA p17 were distinguished by the MAbs with competition ELISA. MAbs from each epitope group were able to recognize 17 North American field isolates of OvLV and the closely related caprine arthritis-encephalitis virus (CAEV). Analysis of the data indicated that these epitopes were highly conserved among naturally occurring isolates. A representative MAb from each epitope group of anti-CA p27 MAbs reacted with four field strains of OvLV and CAEV on immunoblots. An anti-MA p17 MAb recognized the same OvLV strains on immunoblots but failed to recognize CAEV. MAbs which recognize conserved epitopes of gag-encoded lentivirus proteins (CA p27 and MA p17) are valuable tools. These MAbs can be used to develop sensitive diagnostic assays and to study the pathogenesis of lentivirus infections in sheep and goats.

Animals↗

PubMed1991

An epidemiologic study on differences in health status between employed men and women in Hawaii.

Differences in health status between employed men and employed women were examined. 56,203 participants in a stratified random sample of Hawaii's adult population were interviewed during 1981-1986 in the Hawaii Health Surveillance Program. Multiple regression analysis controlling for sociodemographic and occupational variables showed that although the differences were small, employed women reported more health problems than employed men, especially acute conditions and those requiring more hospital services. The findings of this study indicate a need for further study to understand the nature of the observed differences and to develop relevant preventive programs.

Adolescent↗

PubMed1990

Health risk behaviours and ethnicity in Hawaii.

This study has examined the relationships of health-related behaviours to sociodemographic factors with special emphasis on ethnicity in Hawaii. Behavioural variables investigated were non-use of car seat belts, overweight, physical inactivity, smoking, heavier alcohol use, and driving while intoxicated. Sociodemographic factors considered were ethnicity, island, sex, age, education, employment status, marital status, and household income. Major ethnic groups studied were Caucasians, Hawaiians including part-Hawaiians, Chinese, Filipinos, and Japanese. The relationships of ethnic factors with the behavioural characteristics were studied by logistic regression after fitting significant non-ethnic sociodemographic variables. Multiple risk behaviour was investigated by canonical correlation analysis. Different behavioural factors were found to be associated with different sets of non-ethnic socioeconomic variables. There were significant ethnic differences in individual at-risk behaviours except for driving while intoxicated. Overweight was most prevalent among Hawaiians followed by Caucasians. Caucasians and Hawaiians were at higher risk for non-use of seat belts, cigarette smoking, and heavier alcohol use compared to Chinese, Filipinos, and Japanese. Orientals were physically less active than Caucasians and Hawaiians. Implications of the observed ethnic differences are discussed.

Demography↗