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Biomedical subjects

H L Chen

Publications and source records attributed to H L Chen.

At least 145 records · Page 8Linked to original sources
PubMed1995

A single intracerebroventricular injection of dexamethasone elevates food intake and plasma insulin and depresses metabolic rates in adrenalectomized obese (ob/ob) mice.

A single intracerebroventricular (ICV) injection of dexamethasone rapidly (within 30 min to 3 h) increases plasma insulin and suppresses oxygen consumption in adrenalectomized ob/ob mice with minimal effects in lean mice. Food intake of these adrenalectomized ob/ob mice was unaffected by ICV dexamethasone during these short-term studies. However, in a longer-term study with adrenalectomized gold thioglucose-lesioned obese mice, food intake increased fourfold 6-8 d after a single ICV injection of dexamethasone. We have now further examined the time course of dexamethasone actions in adrenalectomized ob/ob and lean mice in the 96-h post-injection period. A single ICV injection of dexamethasone increased food intake 32% and plasma insulin 81%, and depressed oxygen consumption 11%, in adrenalectomized ob/ob mice during the 24-h period after injection, without increasing food intake or plasma insulin in lean mice. Oxygen consumption was 14% lower in lean mice 24 and 48 h after dexamethasone injection relative to saline-injected lean mice. Food intake and oxygen consumption in ob/ob mice returned to levels in saline-injected controls at 48 and 72 h after injection, respectively. Oxygen consumption of lean mice also returned to control levels at 72 h post-injection. Plasma insulin concentrations were similar in dexamethasone- and saline-treated ob/ob and lean mice at 96 h post-injection (the only time point examined other than 24 h). A single ICV injection of dexamethasone exerts both rapid (within 30 min to 3 h) and sustained (days) metabolic actions in ob/ob mice.

Adrenalectomy↗
PubMed1995

CPEO and carnitine deficiency overlapping in MELAS syndrome.

Mitochondrial myopathy, encephalopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome is one of the mitochondrial encephalomyopathies that has distinct clinical features including stroke-like episodes with migraine-like headache, nausea, vomiting, encephalopathy and lactic acidosis. We report a 27-year-old woman who presented with partial seizure, stroke-like episodes including hemiparesis, hemianopia and hemihypethesia, sensorineural hearing loss, migraine-like headache, and lactic acidosis. Brain computed tomographic scan showed encephalomalacia in the right parieto-occipital area and recent hypodensity in the left temporoparieto-occipital area with cortical atrophy. Muscle biopsy revealed ragged-red fibers and paracrystaline inclusions in the mitochondria. Genetic study revealed an A to G point mutation at nucleotide position (np) 3243 of mitochondrial DNA. External ophthalmoplegia and ptosis were also found during two exaggerated episodes in this patient. Therefore, the overlapping syndrome of chronic progressive external ophthalmoplegia in the MELAS syndrome is considered in this case. Furthermore, we also found carnitine deficiency in this patient and she was responsive well to steroid therapy. Muscle biopsy also revealed excessive lipid droplets deposits. Therefore, the carnitine deficiency may occur in MELAS syndrome with the A to G point mutation at np 3243. We recommend the steroid or carnitine supplement therapy be applied to the MELAS syndrome with carnitine deficiency.

Adult↗
PubMed1995

Detection of Rickettsia tsutsugamushi specific DNA from the lymphocyte of patients by polymerase chain reaction.

Polymerase chain reaction was used to detect Rickettsia tsutsugamushi specific DNA from the lymphocytes of patients in the acute phase of the disease. The primers used in the PCR were based on the nucleotide sequences of gene encoding of the 56 kDa antigen of the Gilliam strain. The PCR product is a 78 bp fragment which can be hybridized by the 78 bp DNA probe of the Gilliam strain. Comparison of the results obtained by polymerase chain reaction, immunofluorescent assay and cell culture suggests that the polymerase chain reaction method is the most sensitive one among the three in diagnosis of scrub typhus.

Acute-Phase Reaction↗
PubMed1995

[Isolation of Rickettsia tsutsugamushi from the blood samples of patients in Taiwan].

Scrub typhus, an acute febrile eruptive disease caused by Rickettsia tsutsugamushi, is one of the most commonly reported communicable diseases in Taiwan. However, information about the epidemic trends of scrub typhus in Taiwan is still very limited. Therefore, this study was performed to isolate the causative agent and determine the prevalence of three different serotypes. From June 1992 to December 1994, lymphocyte cell cultures were grown from different regions of Taiwan. Cell cultures were assayed for R. tsutsugamuhi via immuno-fluorescence, using antisera against Gillian, Karp and Kato strains. Thirty-three of the specimens were positive for R. tsutsugamushi, including one from Keelung, 23 from Taitung, 2 from Kinmen and 7 from Lienjan. Of these, 15 were classified as Gillian-related types, 10 were Karp-related types and 8 were not positively classified. These results indicate Gilliam-and Karp-related serotype are more prevalent than the Kato-related serotype in Taiwan.

Base Sequence↗
PubMed1994

Frequent genetic alterations at the distal region of chromosome 1p in human hepatocellular carcinomas.

Cytogenetic analysis of hepatocellular carcinoma (HCC) cell lines and primary HCC tissues has demonstrated chromosome 1p to be the region most commonly affected. To refine the altered locus, genetic abnormalities of this region were surveyed systemically by microsatellite polymorphism analysis. Twelve sets of primers evenly distributed on chromosome 1p which can amplify di- or tetranucleotide repeat length polymorphism by polymerase chain reaction were selected. The results were then supplemented by the conventional restriction fragment length polymorphism study. A comparison of the allele patterns between 30 pairs of HCC and their corresponding nontumor DNAs discovered chromosome 1p aberrations in 15 of 30 tumors (50%). The abnormalities can be classified into three groups. The first aberration was typical loss of heterozygosity that was found in 9 HCCs (30%). The second aberration was a 2-3-fold increase of allelic dosage, which was detected in 6 HCCs (20%). The third aberration was the novel microsatellite polymorphism, which was detected in 3 cases (10%). These abnormalities seemed to cluster at the distal part of chromosome 1p, with a common region mapped to 1p35-36, which is also the region with frequent loss of heterozygosity in neuroblastoma and colorectal and breast cancers. Therefore, loss of putative tumor suppressor gene(s) in this locus may participate in the development of hepatocellular carcinoma and a wide range of human cancers.

Carcinoma, Hepatocellular↗
PubMed1994

Gestation-related expression of the interferon-gamma receptor gene in mouse uterine and embryonic hematopoietic cells.

Macrophages and natural killer (NK)-like cells are the major hematopoietic cell populations in the cycling and pregnant mouse uterus and are also found in the embryo. In order to evaluate potential receptivity of these cells to interferon-gamma (IFN-gamma), tissues taken from cycling and pregnant mice were tested for IFN-gamma receptor (IFN-gamma R) mRNA and protein. Macrophages were identified immunohistochemically by using the specific monoclonal antibody F4/80. NK cells were identified by their large size, distinctive intracellular granules, and binding of a monoclonal antibody to the common leukocyte antigen. In cycling uteri, the abundance of IFN-gamma R mRNA relative to an invariant message (glyceraldehyde-3-phosphate dehydrogenase) increased during progression of the hormonally regulated estrous cycle. IFN-gamma R mRNA in situ hybridization signals were slightly higher in macrophage-like than in other types of endometrial stromal cells. In pregnant uteri, the highest proportions of IFN-gamma R mRNA were observed at gestation day (g.d.) 16. Specific message and protein were present in uterine macrophages by g.d. 7 and in NK cells by g.d. 9. IFN-gamma R expression in both lineages remained stable through the balance of pregnancy. In embryos, IFN-gamma R mRNA increased between g.d. 14 and 16. Specific transcripts were present in many cells at g.d. 14, but none were detected in embryonic liver macrophages until g.d. 16. The results of this study suggest relationships between IFN-gamma R expression and ovarian hormones as well as cell maturation and support the postulate that IFN-gamma receptor-ligand interactions may improve the ability of uterine and embryonic hematopoietic cells to perform specific tasks during gestation.

Animals↗
PubMed1994

Tumor necrosis factor-alpha mRNA and protein in endometrial tumors: analysis by in situ hybridization and immunocytochemistry.

Abnormal expression of polypeptide growth factors and their receptors is closely associated with tumorigenic transformation. In this study tumor necrosis factor-alpha (TNF-alpha) mRNA and protein were analyzed in polyps and proliferative lesions of endometrium as well as in low and high grade endometrial tumors by using in situ hybridization and immunocytochemistry. All samples contained products of the TNF-alpha gene. Histochemical scores (HS), which reflect the proportion of cells positive for TNF-alpha message or protein and the intensities of the signals, were higher for epithelial than for stromal cells. Benign lesions (endometrial polyps) contained little TNF-alpha mRNA or protein, whereas specific message was abundant in proliferative lesions (hyperplasia, adenofibroma). Although neoplastic cells in both low and high grade endometrial tumors contained TNF-alpha mRNA, two major differences were observed: HS for TNF-alpha mRNA were significantly less in low grade than in high grade neoplasms, and TNF-alpha message was restricted to the nucleus in low grade adenocarcinoma cells but was abundant in the cytoplasm of high grade tumor cells. In contrast to cells in benign and proliferative lesions, TNF-alpha protein scores in endometrial tumor cells were inversely rather than positively correlated with TNF-alpha mRNA scores. Collectively, the findings in this study are consistent with the postulate that TNF-alpha is useful to endometrial tumor cells and suggest that production may increase as cells diverge from normal.

Adenocarcinoma↗
PubMed1994

Radiographic technique for acquisition of external patient contour.

Despite advances in techniques for contour acquisition, most patients are still contoured manually using lead wire. The lead wire method has unpredictable inherent inaccuracies due to the fact that the wire must be removed from the patient to obtain the contour. A simple radiographic method for a quick and accurate contour is presented that eliminates such an operator error. The technique requires that a thin lead wire be placed on the patient's skin in the desired plane as in the manual contouring process. With the wire still in place, the simulator table is rotated 90 degrees, and then the gantry is rotated to any reasonable angle (30-45 degrees) for a simple radiograph. The source-to-film distance (SFD) and gantry angle are noted. The radiograph of the lead wire contour is digitized on a personal computer (PC) and transformed from the film coordinates to the patient coordinates using the SFD and the gantry angle as input parameters. The accuracy and efficacy of this method were tested in four test cases: a square box, and contours in the head and neck, thoracic, and pelvic regions. The accuracy of the calculated contour was within +/- 4 mm for the large-gradient contours and +/- 3 mm in the other cases. A root mean square deviation of < 2 mm was observed between this method and the CT contour. This method can be used in any clinical setting where a simulator and a digitizer with a PC are available. The transformation code is simple and could be placed on any treatment planning computer system.

Humans↗
PubMed1994

Corticotropin-releasing hormone decreases feeding, oxygen consumption and activity of genetically obese (ob/ob) and lean mice.

Acute effects of intracerebroventricularly administered corticotropin-releasing hormone (CRH) on deprivation-induced food intake, whole-body oxygen consumption, brown adipose tissue metabolism, and several locomotive behaviors were examined in 6- to 7-wk-old female genetically obese (ob/ob) and lean mice. Corticotropin-releasing hormone depressed food intake in a dose-dependent manner, with a tendency for greater suppression of intake in intact ob/ob mice than in lean mice. Adrenalectomy abolished this tendency for CRH to be more potent in ob/ob mice than in lean mice. Corticotropin-releasing hormone also lowered the oxygen consumption of ob/ob and lean mice, without affecting brown adipose tissue metabolism as assessed by measurement of GDP binding to brown adipose tissue mitochondria. Grooming activity was lowered in CRH-injected mice. The CRH-induced lowering of oxygen consumption and grooming activity in mice contrasts with CRH-induced elevations of oxygen consumption and grooming in rats, suggesting species-specific responses to this peptide. Because effects of CRH were similar in adrenalectomized ob/ob and lean mice, it is unlikely that obesity-producing abnormalities in ob/ob mice are related to abnormal CRH action mechanisms. However, potential abnormalities in CRH synthesis and/or release cannot be excluded.

Adipose Tissue, Brown↗
PubMed1994

HTLV-II non-integrated malignant lymphoma induction in Japanese white rabbits following intravenous inoculation of HTLV-II-infected simian leukocyte cell line (Si-IIA).

Lymphoma induction in rabbits by an unknown factor derived from an HTLV-II-producing simian (Cynomolgus) leukocyte cell line (Si-IIA) is reported. Thirteen of 17 male Japanese white rabbits (76%) inoculated intravenously with Si-IIA cells developed malignant lymphoma including Hodgkin-like lymphoma between 62 and 167 days after inoculation. Histologically, there was extensive diffuse or nodular infiltration of either large cell type or mixed type lymphoma cells in many organs, frequently involving the spleen, liver, lymph nodes and kidneys, and less frequently the thymus, bone marrow, lungs, heart, skin and gastrointestinal tract. Hodgkin-like lymphoma was also observed in two rabbits. Chromosomal analysis of five cell lines established from tumor-bearing rabbits revealed the male rabbit karyotype. The immunophenotype of these tumor cells was usually T-cell (CD5+ or -, RT1+, RT2+ or -, CD45+, CD4-, RABELA- and MHC class II-DQ+) except for Hodgkin-like lymphoma cells which expressed only CD45. However, integration of the HTLV-II provirus genome could not be demonstrated in the tumor tissues or any of the rabbit cell lines by polymerase chain reaction or Southern blot analysis. Moreover, no lymphoma was induced by inoculation of HTLV-IIC, MOT (other HTLV-II-producing human cell lines) or TALL-1 (control). Two of four rabbits injected with cell-free pellets from Si-IIA cultures died of malignant lymphoma (15-20 days). Five irradiated rabbit cell lines were inoculated but only one (Ra-SLN) induced lymphoma in 1 of 3 rabbits at 27 days. Neither Herpesvirus saimiri nor Herpesvirus ateles (simian oncogenic viruses) was detected in Si-IIA cells by immunofluorescence testing. These data suggest that the high rate of lymphoma induction in rabbits may be caused not by only HTLV-II or well known simian oncogenic viruses, but rather by an unknown passenger agent derived from Si-IIA or HTLV-IIA, with which Si-IIA was established.

Animals↗
PubMed1994

Alteration of pulse in human subjects by three Chinese herbs.

Human subjects were fed with extract of three Chinese herbs, Panax ginseng, Panax quinquefolium roots and Ganoderma lucidum. Pulse of the radial artery was examined. Our results indicate that each herb has a specific effect on the Fourier components of the pulse, and is in agreement with traditional Chinese medical descriptions.

Adolescent↗
PubMed1994

Type II glucocorticoid receptors in the CNS regulate metabolism in ob/ob mice independent of protein synthesis.

A single intracerebroventricular injection of dexamethasone rapidly (within 30 min) decreases brown adipose tissue thermogenesis by 25% as assessed by GDP binding and increases plasma insulin twofold in adrenalectomized ob/ob mice. The present study investigated the type of corticoid receptor(s) that mediate these effects and determined whether protein synthesis was necessary for expression of these glucocorticoid actions in ob/ob mice. Intracerebroventricular injection of aldosterone (a type I-corticoid receptor agonist) was ineffective in altering peripheral metabolism in adrenalectomized ob/ob mice, whereas RU-486 (a type II-corticoid receptor antagonist) abolished the effects of dexamethasone. Thus type II-like corticoid receptors, not type I receptors, mediated the rapid effects of dexamethasone in adrenalectomized ob/ob mice. Anisomycin (0.5 mg) administered subcutaneously almost completely suppressed (-92%) cerebral protein synthesis, but anisomycin did not abolish the rapid effects of dexamethasone in adrenalectomized ob/ob mice. Thus protein synthesis is not a prerequisite for rapid effects of dexamethasone in adrenalectomized ob/ob mice.

Adipose Tissue, Brown↗
PubMed1994

Hearing in the elderly. Relation of hearing loss, loneliness, and self-esteem.

1. The prevalence of hearing impairment increases with age. Hearing handicap resulting from hearing loss may lead to psychosocial problems in elders. 2. Previous studies have shown relations among hearing handicap, loneliness and low self-esteem, but those studies focused on populations other than elders. 3. Early detection of hearing handicap and appropriate interventions promote increased independence and preserve the ability of elders to interact with their environment.

Aged↗
PubMed1994

Q fever in Taiwan.

BACKGROUND: Although Q fever, a rickettsial disease caused by Coxiella burnetii, is supposed to occur sporadically worldwide, there is only one case report of this disease in Taiwan. We examined the antibody of Q fever to evaluate the status of Q fever in Taiwan. METHODS: In total, 579 paired serum specimens of suspected febrile patients sent by several hospitals and sanitary stations to this Institute in 1991 and 1992 were tested according to the technique of indirect fluorescent antibody (IFA). RESULTS: In total 48 serologically acute Q fever cases were found, mostly from Tainan, Pingtung and Kaohsiung. There was only one female, and the age of most patients was 40-50 years. The high season is in June and July. CONCLUSIONS: The antibody titer of all 48 positive cases reached 1:320 or higher on the 13th day after onset of the disease. IFA as a diagnostic tool to detect acute and convalescent serum antibody titer is discussed.

Adult↗
PubMed1993

Molecular, biochemical, and functional characteristics of tumor necrosis factor-alpha produced by human placental cytotrophoblastic cells.

Previous studies have shown that the TNF-alpha gene is transcribed and translated in fully differentiated human placental syncytiotrophoblast. In this study, TNF transcripts were identified by in situ hybridization in cytotrophoblastic cells, a progenitor subpopulation that proliferates rapidly in early gestation tissues. To establish molecular and biochemical characteristics of cytotrophoblastic TNF and to evaluate potential utilization, experiments were conducted on two cytotrophoblastic cell lines, Jar and JEG-3. Northern blot hybridization and immunocytochemical tests showed that Jar and JEG-3 cells contained TNF mRNA and specific protein. Enzyme immunoassays demonstrated production of TNF, and immunoprecipitation experiments showed that Jar cell TNF protein was the same molecular mass as macrophage TNF. DNA synthesis in both lines was promoted by rTNF, and experiments employing 17-mer TNF antisense and sense oligonucleotides showed specific inhibition of DNA synthesis by antisense sequences. Both p60 and p80 TNF-R mRNA were present in the choriocarcinoma cell lines, and DNA synthesis was inhibited by antibody to the p60 TNF-R. Although the two lines were similar in many respects, Jar cells produced more TNF and demonstrated a greater reliance on TNF for their growth. Collectively, the results indicate that: 1) the TNF gene is expressed in both normal and malignant cytotrophoblast; 2) certain molecular, immunologic, and biochemical characteristics of trophoblast-derived TNF are similar to macrophage TNF; and 3) the p60 TNF-R facilitates utilization of TNF as an autocrine growth factor by choriocarcinoma cells. Although TNF apparently serves important functions in cytotrophoblast during the course of placental development that might include promotion of proliferation and invasion, constitutive expression of this gene in neoplastic cells could account in part for the remarkable ability of trophoblastic tumors to overcome host defenses.

Base Sequence↗
PubMed1993

Prostaglandin E2 suppresses phytohemagglutinin-induced immune responses of normal human mononuclear cells by decreasing intracellular glutathione generation, but not due to increased DNA strand breaks or apoptosis.

Prostaglandin E2 (PGE2) at concentrations more than 1 x 10(-8) M markedly suppressed the cell proliferation and release of soluble molecules of interleukin-2 receptor (sIL-2R), CD4 (sCD4) and CD8 (sCD8) from phytohemagglutinin (PHA)-stimulated normal human mononuclear cells (MNC) in a dose-related manner. To further elucidate the subcellular mechanism of the inhibitory effect of PGE2 on PHA-stimulated MNC, intracellular concentration of glutathione (GSH) in PHA-stimulated MNC was sequentially measured from day 1 to day 3 by enzymic method. Furthermore, the effect of PGE2 on nuclear DNA including DNA strand breaks in alkali treatment and DNA fragmentation (apoptosis) of PHA-stimulated MNC were also measured. We found intracellular GSH levels were significantly decreased in the early stage of lymphocyte activation (day 1), but no evidence of increased DNA strand breaks or apoptotic process appeared in 3-day culture. In addition, butathione sulfoximine (a specific GSH inhibitor) and dibutyryl cyclic AMP also exhibited both proliferation inhibition and GSH-decreasing effects on PHA-stimulated MNC as well as PGE2. These results suggest that the immunosuppressive effect of PGE2 is mediated by the decreased generation of intracellular GSH, but not by the increased DNA strand breaks or apoptotic mechanism in the cells.

Antimetabolites↗
PubMed1993

Identification of transforming growth factor-beta 1 mRNA in virgin and pregnant rat uteri by in situ hybridization.

Transforming growth factor-beta 1 (TGF-beta 1) has major effects on hematopoietic cell proliferation, migration and function. In an effort to learn whether or not TGF-beta 1 might be among the cytokines that influence uterine, placental and embryonic hematopoietic cells, in situ hybridization was used to map expression of the TGF-beta 1 gene through gestation in the rat. In cycling uteri, hybridization signals with a biotinylated TGF-beta 1 antisense RNA probe were comparatively weak and were restricted to myometrium. During pregnancy, TGF-beta 1 mRNA appeared in specific cell lineages in an ordered temporal sequence. In early post-implantation tissues (g.d. 5-8), TGF-beta 1 transcripts were prominent in uterine epithelial cells, muscle and decidual cells. At g.d. 15, hybridization signals were particularly strong in uterine epithelial cells, muscle and placental trophoblast cells. At this stage, TGF-beta 1 mRNA was also present in uterine cells resembling macrophages and in natural killer-like (GMG) cells. Steady state levels of specific message in uteri and placentas declined at late stages of gestation (g.d. 18, 21). In rat embryos, specific transcripts were identified at g.d. 9 and were prominently displayed in various types of embryonic cells from mid-gestation onwards. The results of this study are consistent with the postulate that throughout pregnancy in the rat, TGF-beta 1 may, in addition to its other functions, influence the proportions, patterns of distribution and activities of maternal and fetal hematopoietic cells.

Animals↗