Biomedical subjects

C K Ho

Publications and source records attributed to C K Ho.

At least 91 records · Page 5Linked to original sources

PubMed1997

[Chemical burn caused by hydrofluoric acid in Kaohsiung area--a 5-year experience].

Hydrofluoric acid (HF) has been used extensively in industry and laboratory, and also is a common agent for occupational chemical burn. Severe pain and destruction of deep tissue layers occurred when skin was injured by hydrofluoric acid. Some fatal change may happen especially when hydrocalcemia was induced. For presentation of its special character and the use of antidote, we report one outbreak and six individual victims of hydrofluoric acid injury during the previous 5 years in Kaohsiung area. We hope medical personnel could have more accurate management and clinical care for those who are injured by HF, and workers should pay attention to any chemical agents they use to prevent any further injury as a result of careless use of such chemicals.

Adult↗

PubMed1997

REM sleep behaviour disorder in the elderly.

REM sleep behaviour disorder is a recently described parasomnia characterized by a history of excessive motor activities during sleep and is associated with pathological absence of muscle atonia during REM sleep. There is very limited literature on the condition. Two out of 349 elderly patients referred to a psychogeriatric unit were identified to have REM sleep behaviour disorder. These two patients are presented to illustrate the clinical features of the condition. Both of them showed a good response to clonazepam treatment.

Aged↗

PubMed1996

An infant with a mosaic 45,X/46,X,psu dic(Y) (pter-->q11.2::q11.2-->pter) karyotype and mixed gonadal dysgenesis studied for extent of mosaicism in the gonads.

AN infant with mixed gonadal dysgenesis was found to have a 45,X/46,Xpsu dic(Y) karyotype. A low level (8%) of mosaicism for the dic(Y) cell line was observed in peripheral blood lymphocytes and skin fibroblasts. The dicentric nature of the Y chromosome became apparent in fluorescence in situ hybridization studies. The presence of Y centromeric sequences was demonstrated in the paraffin-embedded testis and streak ovary sections. The ration of Y-positive cells was higher in the testis than in the streak ovary.

Chromosome Aberrations↗

PubMed1996

Flanking residues alter antigenicity and immunogenicity of multi-unit CTL epitopes.

CD8+ CTL responses constitute a critical component for vaccines developed to eliminate intracellular pathogens. One approach to achieve broad CTL diversity is based on genetically linking immunogenic peptides from multiple proteins to form poly-epitope Ags. To address the influence of flanking residues on class I Ag presentation, H-2d-restricted HIV-1 and mouse hepatitis virus CTL epitopes were linked via various spacer residues. The resulting 20 to 31 amino acid peptides were expressed using recombinant vaccinia viruses to monitor both CTL recognition and induction. Our data indicate that recognition is profoundly influenced by the nature of intervening residues forming carboxyl-terminal flanks for one and amino-terminal flanks for the other epitope. Flanking amino acids with aromatic (tyrosine), basic (lysine), and small aliphatic side chains (alanine) supported efficient CTL recognition of both epitopes. By contrast, acidic and helix breaking residues (glycine, proline) specifically inhibited recognition of the adjacent amino-terminal epitope. Flanking residues inhibitory for recognition were also detrimental for CTL induction, suggesting similar processing mechanisms in vitro and in vivo. The ratios of peptide-specific CTL precursors primed by the tandem epitopes varied up to 50-fold depending on molecular context. These data demonstrate a substantial role of carboxyl-flanking residues in governing the efficiency of class I Ag presentation both in vitro and in vivo. The dramatic influence of flanking residues on the hierarchy of CTL responses indicates that CTL induction by poly-epitope Ags can be optimized by strategically linking epitopes via selection of appropriate spacer residues.

Animals↗

PubMed1996

Physical and functional characterization of the double-stranded RNA binding protein encoded by the vaccinia virus E3 gene.

The vaccinia virus E3 gene encodes a 190-amino acid double-stranded (ds) RNA-binding protein that antagonizes cellular antiviral response pathways triggered by dsRNA and interferon. The physical and functional properties of the E3 protein were determined using recombinant E3 produced in bacteria and purified to homogeneity. We show by sedimentation and chemical crosslinking that E3 is a dimer in solution at high ionic strength. E3 self-associates to form higher order oligomers as ionic strength is reduced from 1 to 0.1 M NaCl. Structure probing by limited proteolysis suggests that E3 consists of amino- and carboxyl-terminal domains separated by a trypsin-sensitive bridge at residues Lys-92 and Arg-95. The carboxyl-domain of E3 contains a conserved dsRNA binding motif (dsRBM) found in many other proteins that interact with dsRNA. That the C-terminal domain per se binds to dsRNA was verified by studies of recombinant E3(100-190) purified from bacteria. The affinity of the C-terminal domain for dsRNA was comparable to that of the full-length E3 protein (KD approximately 7 to 9 nM). E3(100-190) did not bind to DNA-DNA duplexes or to DNA-RNA hybrids, suggesting that the dsRBM specifically recognizes an A-form helix. E3(100-190) is a dimer in solution; however, unlike the full-sized E3 protein, E3(100-190) does not form higher order multimers at low ionic strength.

Base Sequence↗

PubMed1996

Expression and characterization of an RNA capping enzyme encoded by Chlorella virus PBCV-1.

We report that the A103R protein of Chlorella virus PBCV-1 is an mRNA capping enzyme that catalyzes the transfer of GMP from GTP to the 5' diphosphate end of RNA. This is a two-step reaction in which the enzyme first condenses with GTP to form a covalent enzyme-GMP intermediate and then transfers the GMP to an RNA acceptor to form a GpppN cap. Purified recombinant Al03R is a 38-kDa monomer that lacks RNA (guanine-7-) methyltransferase activity. With respect to its size, amino acid sequence, and biochemical properties, A103R is more closely related to the yeast RNA guanylyltransferases than it is to the multifunctional capping enzymes coded for by other large DNA viruses--the poxviruses and African swine fever virus. We surmise that in order to cap its transcripts, PBCV-l must either encode additional 5' processing activities or else rely on the host alga to provide these functions.

Chlorella↗

PubMed1996

Mutational analysis of the vaccinia virus E3 protein defines amino acid residues involved in E3 binding to double-stranded RNA.

Alanine-substitution mutations were targeted to 14 amino acid residues within the double-stranded (ds) RNA binding motif (dsRBM) of the vaccinia virus E3 protein. Substitutions at six positions--Glu-124, Phe-135, Phe-148, Lys-167, Arg-168, and Lys-171--caused significant reductions in dsRNA binding. These six residues are conserved in the two dsRBMs for which structural information is available (Escherichia coli RNase III and Drosophila melanogaster staufen) and in many other members of the dsRBM protein family. Residues we show to be important for dsRNA binding by vaccinia virus E3 map to the same face of the dsRBM structure and are thus likely to compose part of the RNA binding site.

Amino Acid Sequence↗

PubMed1996

Cathepsin D and epidermal growth factor receptor immunohistochemistry does not predict recurrence of prostate cancer in patients undergoing radical prostatectomy.

PURPOSE: We determined if immunohistochemical expression of the epidermal growth factor receptor and cathepsin D in the primary tumor was of prognostic value in clinically localized prostate cancer after radical prostatectomy. MATERIALS AND METHODS: Immunohistochemical staining for epidermal growth factor receptor and cathepsin D was performed on 105 radical prostatectomy specimens from 2 academic centers. The epidermal growth factor receptor and cathepsin D expressions were graded using H scoring by an experienced pathologist blinded to other patient data, and compared with age, grade, stage, race and initial serologic (prostate specific antigen) recurrence. Univariate and multivariate statistical testing was performed. RESULTS: Immunohistochemically detectable epidermal growth factor receptor and cathepsin D expression was not correlated to age, race, stage or Gleason grade. In univariate and multivariate testing epidermal growth factor receptor and cathepsin D were not prognostic markers for disease progression following radical prostatectomy. CONCLUSIONS: Immunohistochemical analysis of the biomarkers cathepsin D and epidermal growth factor receptor in radical prostatectomy specimens does not predict disease recurrence. Further biological marker study is needed in clinically localized prostate cancer.

Aged↗

PubMed1996

Constitutive production of colony-stimulating factors by human hepatoma cell lines: possible correlation with cell differentiation.

A panel of two poorly differentiated (HA22T/VGH and SK-Hep-1) and six well-differentiated (HuH-6-cl 5, HuH-7, PLC/PRF/5, Hep G2, Hep 3B, and Tong) human hepatocellular carcinoma (HCC) cell lines were studied for the production of colony-stimulating factors (CSFs) using the granulocyte and macrophage colony formation (CFU-GM) assay, immunocytochemical staining, and Northern blotting. Medium conditioned by untreated HA22T/VGH cells contained a high level of CSFs that could stimulate the in vitro colony formation of human myeloid progenitor cells. The HA22T/VGH cell-derived CSF had an apparent molecular weight of 23 kD. Its activity could be effectively neutralized by antiserum against granulocyte-macrophage CSF (GM-CSF) but not by antibodies to other hematopoietic growth factors, including G-CSF, M-CSF, interleukin-3 (IL-3), and IL-6. Correspondingly, immunocytochemical studies using monoclonal anti-GM-CSF showed a strong positive reaction in the cytoplasm of the HA22T/VGH cells. Northern blot analysis revealed that untreated HA22T/VGH cells expressed a considerable amount of GM-CSF mRNA, confirming that GM-CSF production was constitutive. At optimal concentrations, lipopolysaccharide (LPS), IL-1beta, interferon-gamma (IFN-gamma), and tumor-promoting phorbol diester (TPA) could all stimulate HA22T/VGH cells to secrete GM-CSF. In addition to HA22T/VGH, SK-Hep-1 cells could also produce GM-CSF, although less effectively, whereas all the well-differentiated HCC cell lines tested were negative for CSF production. Morphologic, cytochemical, and immunocytochemical examinations demonstrated that both poorly differentiated CSF-producing HCC cell lines (HA22T/VGH and SK-Hep-1) were macrophage-like in morphology, possessed nonspecific esterase (NSE) activity, and expressed CD14, CD68, and HLA-DR on their surface, while all the well-differentiated HCC cell lines were epithelioid and lacked myeloid differentiation antigens. These results suggest that monocytoid features and CSF production may be differentiation markers of hepatocytes at the immature stages, amd that the HA22T/VGH and SK-Hep-1 cell lines may be valuable tools for the study of hepatic function and differentiation.

Blotting, Northern↗

PubMed1996

[The influence of job characteristics and workplace subculture on individuals' drinking behavior--an exploratory pilot study].

The purpose of this study was to explore how individuals' drinking behavior was associated with their jobs in terms of the amount consumed and its consequences. The researchers attempted to analyze the characteristics of job and workplace from structural, psychological, and cultural perspectives. The structural dimension referred to years serving in a company, years serving in a department, work position, work characteristics, and shift. The psychological dimension was addressed on perceived stress and work hazards. The cultural dimension of one's job consisted of formal and informal norms regarding one's drinking within the workplace. The result showed the occurrence of drinking-related problems was significantly associated with workplace subculture among the non-aboriginal Chinese males. However, none of the three perspectives as job characteristics was significantly associated with drinking amount. The findings imply that the workplace subculture plays a determinant role in affecting individual's drinking behavior, moreover, it could result in one's problem drinking.

Adolescent↗

PubMed1996

Fiberglass dermatitis: a case report.

Glass fibers are the most widely distributed mineral fibers because of their multiple applications, chiefly as insulation materials, and have become important in replacing asbestos fibers. Fiberglass dermatitis is one of the most common forms of occupational dermatitis resulting from mechanical irritation. Here we report a typical case. A 30-year-old male worker handled the cutting and grinding of fiberglass mats and then mixed them with resin as reinforcing materials. He complained of intense itching after the first two weeks of employment. Erythematous macules, papules and folliculitis with excoriation developed over his arms, neck, face and upper chest. There were many transparent glass fiber spicules with the diameter around 7-10 microns detected by applying the adhesive tape against the skin lesion, followed by microscopic observation. He was much improved during hospitalization with oral antihistamine and topical steroid ointment. To prevent this occupational disease, we suggest proper procedures of production, storage, transportation and cleaning in the industrial setting and proper protective clothing in personnel to minimize the release of and exposure to glass fibers.

Adult↗

PubMed1996

[Job strain and drinking behavior].

The aim of this survey study was to explore the influence of work on individual's drinking behavior. From October 1994 to March 1995, the present researchers implemented a self-administered questionnaire survey on workers in the manufacturing sector in Metropolitan Kaohsiung area, southern Taiwan. Of the 1,117 subjects selected, 668 (61.8%) stated that they had had one or more drinks during the preceding month. The average daily consumption of alcohol was 0.2 +/- 0.9 drinks (with a range of 0 to 12 drinks and a median of 0.02 drinks). In addition, 188 (28.8%) of the subjects reported having experienced drinking-related problems during the preceding month, and 35 respondents (5.2%) gave escape from job stress as the reason for their drinking in the preceding month. The result of multivariate analyses showed that workers who reported less autonomy in their job were more likely to experience drinking-related problems (odds ratio [OR] = 1.3) and to drinking for psychological relief (OR = 1.2); that workers who reported more demanding job conditions were more likely to drink for escape (OR = 2.5) but had lower levels of drinking (t = -2.5, p = 0.01); and that workers who reported high levels of job strain were more likely to experience drinking-related problems and to drink for relief but had lower levels of drinking. The details and implications of this result will be discussed.

Adolescent↗

PubMed1995

Pathology of androgen deprivation therapy in prostate carcinoma. A comparative study of 173 patients.

BACKGROUND: Leuprolide, an agonist of luteinizing hormone-releasing hormone (LH-RH), and flutamide, an antiandrogen, increasingly are being used in the treatment of clinically localized prostate cancer. Only two small series (of 23 and 12 patients) have been published on the distinctive pathologic changes induced in the prostate by androgen deprivation therapy with discrepancies on the presence of squamous metaplasia, necrosis, and possible tumor destruction by combined androgen deprivation therapy. METHODS: One hundred and thirteen radical prostatectomy specimens obtained after at least 3 months of leuprolide-flutamide androgen inhibition therapy and 60 nonhormonally treated prostates in randomly selected clinical Stage T2 prostate adenocarcinoma patients were entirely sectioned. Distinctive histologic findings were tabulated and their statistical value determined. RESULTS: Resection margins of excision were involved by tumor in 43% of untreated and in 19% of androgen-deprived patients. Characteristic changes in androgen-inhibited nontumor glands included atrophy, basal cell prominence, vacuolated luminal cell layer, and squamous and transitional cell metaplasia. Prostatic intraepithelial neoplasia (PIN) was observed in 35% of treated patients. The presence of small tumor glands separated by stroma was the most frequently noted effect of androgen deprivation on prostate adenocarcinoma; pyknosis and branching empty spaces were less frequent. Large clear tumor cells within an inflammatory response was a third histologic pattern. Apparently unaltered tumor areas were observed in 43% of prostates exposed to androgen deprivation therapy. CONCLUSIONS: Androgen deprivation therapy results in histologically distinctive changes that can be recognized in both nonneoplastic and neoplastic prostate tissue. Residual tumor was present in all 113 treated radical prostatectomy specimens. In addition to glandular shrinkage, therapy was associated with statistically significant reductions in the frequency of high grade PIN and extension of cancer to prostate specimen margins of excisions.

Androgen Antagonists↗

PubMed1995

Effect of lymphocytes on the production of granulomonopoietic enhancing factor by fully mature macrophages.

The granulomonopoietic enhancing factor (GM-EF) is a novel myelopoietic regulator produced by human monocyte-derived lipid-containing macrophages (MDLMs). In the present study, we examined the effect of lymphocytes on GM-EF production by preincubation of MDLMs with various preparations of lymphocyte subpopulations in cell-mixed and in double agar layer cultures. Our results showed that a cell concentration-dependent suppression of GM-EF production was noted in cultures with mitogen-activated T cells, and mitogen-activated/resting B cells, while those containing resting T cells had no such effect. Thus, GM-EF production in the presence of 1 x 10(5)/ml activated T cells or activated/resting B cells was greatly reduced to 5% or 20%, respectively. The lymphocyte-induced suppression was evident in both cell-mixed and double layer cultures, implying that the effector cells might exert their influences via mediators. Assay for cytokine activity revealed that a high level (648.2-685.2 pg/ml) of tumor necrosis factor-alpha (TNF-alpha) was found in MDLM cultures with resting/activated B cells, and in those with activated T cells high levels of both TNF-alpha (510.5 pg/ml) and interferon-gamma (IFN-gamma) (321.3 pg/ml) could be detected, whereas in cultures with MDLMs and/or resting T cells, these cytokines were not measurable. Treatment of MDLMs with either recombinant (r) TNF-alpha or rIFN-gamma invariably resulted in a dose-dependent decrease in GM-EF production with intense suppression at doses between 400-800 U/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

B-Lymphocytes↗

PubMed1995

Establishment of an occupational diseases surveillance system to monitor blood lead levels in Taiwan.

BACKGROUND: Occupational diseases share many common characteristics with infectious diseases. However, the successful approach of using surveillance systems to eradicate infectious diseases has never been applied to the control and prevention of occupational diseases. METHODS: On the basis of a nationwide survey of blood lead levels in the general population in Taiwan, we (the Ministry of Health, Taiwan) have developed an obligatory surveillance system for blood lead. RESULTS: This government-administered system, which uses laboratory data as its source of information, enrolls all workers whose blood lead level exceeds regulation points (40 microgram/dl for men and 30 micrograms/dl for women). A Group of Health Promotion of Lead-using Workers (GHPLW) has been organized to be responsible for conducting epidemiological investigations to locate exposure sources in the workplace and to improve the working environment of cases and other workers with the same exposure. CONCLUSIONS: We emphasize that the accomplishment of the GHPLW's task depends not only on "curing" the case, but also on eradicating the lead exposure source and decreasing the blood lead level of workers in the workplace during long-term follow-up. The system aims to upgrade occupational disease control to the stage of specific prevention and health promotion. The establishment of this system is a historic step in industrial hygiene and occupational disease prevention in Taiwan.

Female↗

PubMed1995

Production of a monoclonal antibody to an antigen present on both trophoblasts and leukocytes.

In the present study, we report the establishment of a monoclonal antibody (Mab) designated F10 that recognized an antigen commonly shared by human trophoblasts and leucocytes. F10 MAb was obtained using cell membrane components from a trophoblast cell line HT as immunogen. Based on immunochemical studies, the F10 reactive antigen (F10-Ag) could be located on both villous and nonvillous trophoblasts from early and term placental tissues and on all trophoblastic cell lines. In addition, flow cytometry revealed that most ( > 95%) peripheral blood lymphocytes, monocytes, as well as polymorphonuclear leukocytes (PMN) were positively stained with F10 MAb. Immunoblotting with F10 MAb identified two protein bands with apparent molecular mass of 62 and 56 kDa. Furthermore, the antigens were glycoproteins and were glycosylated via the O-linkage. Scatchard plot analyses of the binding data between 125I-labeled MAb F10 IgG and HT cells revealed a single class of F10 binding sites with an apparent dissociation constant (Kd) of 10.54 +/- 2.03 pM and maximum binding-site (Bmax) value of 2.1 +/- 0.11 x 10(6) sites per cell. We suggest that F10 may be useful for the identification of a novel epitope that is commonly shared by all trophoblasts and leukocytes and such an epitope may be potentially active in maternal-fetal interactions.

Antibodies, Monoclonal↗

PubMed1995

Some new insights into bladder function in infancy.

OBJECTIVES: To evaluate normal bladder function and micturition patterns in infants. PATIENTS, SUBJECTS AND METHODS: Twenty-one infants (16 boys, five girls; mean age 5.9 months) with no lower urinary tract pathology underwent natural filling cystometry. Micturition patterns were also observed simultaneously with polysomnography in 26 healthy neonates (16 boys, 10 girls; mean age 7.4 days). RESULTS: In infants, cystometry showed (95% CI) a capacity of 42-53 mL, a maximum rise in detrusor pressure during voiding of 95-120 cmH2O and a voiding efficiency (voided volume/capacity) of 0.86-0.91. On micturition, urinary flow was discoordinated from peak detrusor pressures in 10 infants. Detrusor instability occurred in one of 21 infants. Micturition was observed only during wakefulness or on arousal from sleep. In neonates, 17 of 61 recorded voids (28%) were during full wakefulness and 44 (72%) during arousal from sleep. Notably, none of the recorded voids occurred during quiet sleep. CONCLUSIONS: The normal infant's bladder was stable and emptied almost completely. Voiding with incomplete co-ordination between detrusor contraction and urinary sphincter relaxation could be normal. Micturition never occurred during quiet sleep. There was cortical arousal in response to a full bladder even in new-born infants. This contradicts the traditional concept of a totally uninhibited bladder in infancy. There are potential implications for the management of children with nocturnal enuresis.

Female↗

PubMed1994

Effect of arginase on splenic killer cell activity in patients with gastric cancer.

Arginase has been detected in high levels in gastric cancer tissues. The effect of arginase on the activities of splenic natural killer (NK) cell, phytohemagglutinin activated killer (PAK) cell, and interleukin-2 activated killer (LAK) cell in patients with gastric cancer (N = 12) was evaluated in vitro. These activities in patients (N = 10) with trauma and benign lesions were used as control. The splenic NK and PAK cell activities in patients with gastric cancer were significantly lower than in the controls (P < 0.05), whereas LAK cell activity did not have significant difference. Arginase inhibited all splenic killer cell activities to a similar degree between patients with gastric cancer and the controls. The inhibition was dose-related. These data suggest that arginase may play a positive role in the spread of gastric cancer cells. However, LAK may be a potential approach of immunoadoptive therapy in the future.

Arginase↗