Biomedical subjects

J Hua

Publications and source records attributed to J Hua.

At least 55 records · Page 3Linked to original sources

PubMed1999

Reduction in visceral adipose tissue is associated with improvement in apolipoprotein B-100 metabolism in obese men.

We investigated the effect of reduction in visceral obesity on the kinetics of apolipoprotein B-100 (apoB) metabolism in a controlled dietary intervention study in 26 obese men. Hepatic secretion of very low density lipoprotein (VLDL) apoB was measured using a primed, constant, infusion of 1-[13C]leucine. In seven men receiving the reduction diet, intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) apoB kinetics were also determined. ApoB isotopic enrichment was measured using gas chromatography-mass spectrometry, and SAAM-II was used to estimate the fractional turnover rates. Subcutaneous and visceral adipose tissues at the L3 vertebra were quantified by magnetic resonance imaging. With weight reduction there was a significant decrease (P < 0.05) in body mass index, waist circumference, and visceral adipose tissue. The plasma concentrations of total cholesterol, triglyceride, insulin, and lathosterol also significantly decreased (P < 0.05). Compared with weight maintenance, weight reduction significantly decreased the VLDL apoB concentration, pool size, and hepatic secretion of VLDL apoB (delta+2.5+/-4.6 vs. delta-14.7+/-4.0 mg/kg fat free mass-day; P = 0.010), but did not significantly alter its fractional catabolism. Weight reduction was also associated with an increased fractional catabolic rate of LDL apoB (0.24+/-0.07 vs. 0.54+/-0.10 pools/day; P = 0.002) and conversion of VLDL to LDL apoB (11.7+/-2.5% vs. 56.3+/-11.4%; P = 0.008). A change in hepatic VLDL apoB secretion was significantly correlated with a change in visceral adipose tissue area (r = 0.59; P = 0.043), but not plasma concentrations of insulin, free fatty acids, or lathosterol. The data support the hypothesis that a reduction in visceral adipose tissue is associated with a decrease in the hepatic secretion of VLDL apoB, and this may be due to a decrease in portal lipid substrate supply. Weight reduction may also increase the fractional catabolism of LDL apoB, but this requires further evaluation.

Adipose Tissue↗

PubMed1999

Migration of the uncemented CLS acetabular component.

The migration of uncemented press-fit CLS (Cementless Total Hip Replacement System) acetabular cups was measured retrospectively from standard anteroposterior pelvic radiographs using a digitizer and software specifically developed for this study. A radiographic and clinical review also were undertaken. There were 96 patients in the study group. The mean follow-up for radiographic review was 2.23 years, and the mean follow-up for clinical review was 3 years. Migration was measured in the cranial and medial directions. Mean migration of the cup at 2 years was 1.35 mm in the cranial direction and 2.15 mm in the medial direction. Radiographic appearances altered little over the study period. Fifty-five (57.3%) patients demonstrated bone ingrowth onto the prosthesis, predominantly in DeLee and Charnley zone 1. Twenty-one patients demonstrated nonprogressive sclerotic lines; no lucent lines were encountered. Statistical analysis showed a significant correlation between acetabular ingrowth and reduced cup migration in the medial direction (P = .011 at 5 years). There was no statistical relationship between migration of the cup and radiographic features or clinical outcome.

Acetabulum↗

PubMed1999

Migration of the uncemented CLS femoral component.

The migration of uncemented CLS (Cementless Total Hip Replacement System) femoral stems was measured retrospectively from standard anteroposterior pelvic radiographs using a digitizer and software specifically designed for this study. The study population was comprised of 117 patients with 126 uncemented CLS femoral stems. All radiographs were reviewed and the incidence of thigh pain obtained by means of a questionnaire. The mean clinical follow-up was 3 years and the mean follow-up for radiographic review was 2.77 years. The mean femoral stem migration was 2 mm at 2 years and 3.66 mm at 7 years. Radiographic features varied little with no specific predictive features in patients with excessive early migration or those who complained of thigh pain. There was no statistical relationship between the presence of thigh pain and femoral stem migration.

Adult↗

PubMed1999

The neuromuscular compartments of the flexor carpi ulnaris.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Report on the vascular supply and innervation pattern of the flexor carpi ulnaris. 2. Describe the muscle architecture of the flexor carpi ulnaris, including the physiological cross-sectional area and fiber length. 3. State the uses of the flexor carpi ulnaris both for resurfacing defects in the vicinity of the elbow and in local functional tendon transfers. 4. Understand the principles of splitting skeletal muscles based on neurovascular supply to enhance its utilization in reconstructive procedures. The aim of this study was to describe the intramuscular innervation and vascular supply of the human flexor carpi ulnaris, with confirmation of findings by a similar study in the primate. Two distinct intramuscular nerve branches running parallel to each other, on either side of a central tendon, from the proximal quarter of the muscle belly to its insertion were found. The muscle could then be split into a humeral and an ulnar compartment, each with its own primary nerve branch. Perfusion studies confirmed the adequacy of circulation to the two compartments. In the primate flexor carpi ulnaris, electrical stimulation of the respective branches revealed independent contraction of each compartment. This study provides useful information for enabling the local transfer of the muscle as a whole, both for resurfacing in the vicinity of the elbow and for functional tendon transfers. It will also enable the transfer of the muscle as one or two separate compartments (for resurfacing, in tendon transfers for muscle paralysis, congenital defects, and muscle defects resulting from trauma, and after resections for neoplasm and infection).

Animals↗

PubMed1999

Unchanged characteristics of Helicobacter pylori during its morphological conversion.

Helicobacter pylori strains RH 54 and NCTC 11637 were grown in brain-heart infusion broth up to 56 days, and the coccoid form was obtained during prolonged incubation. Two morphological types of coccoids were observed, one of which was electron-dense and had an intact cellular membrane and flagella, indicating that it was likely to be viable. The other coccoid form was sphaeroblast-like and weakly stained, showing features of degeneration. Catalase activity was positive for aged cultures even up to 160 days. Sodium dodecyl sulphate polyacrylamide gel electrophoresis showed that most of the protein bands appeared to be similar in both the spiral and coccoid forms. In addition, Lewis blood group antigens were detected in cultures of up to 8 weeks. Furthermore, two sets of primers for the vacA and cagA genes were used in polymerase chain reaction, and these two important genes remained conserved in both the spiral and coccoid forms. The present study shows that the coccoid form of H. pylori retained many important characteristics present in the spiral form despite the morphological conversion, and thus supports the notion that some of the coccoid forms of H. pylori are likely to be viable.

Antigens, Bacterial↗

PubMed1999

Effects of Kupffer cells stimulated by triglyceride and very low-density lipoprotein on proliferation of rat hepatic stellate cells.

OBJECTIVE: To study the effects of triglyceride, very low-density lipoprotein (VLDL), and Kupffer cell-conditioned medium (KCCM) derived from triglyceride and VLDL treatment on proliferation of rat hepatic stellate cells (HSC). METHODS: HSC and Kupffer cells were isolated and cultured from liver of Wistar rats by in situ perfusion with proteinase and collagenase, and density gradient centrifugation with Nycodenz; HSC and Kupffer cells were identified by immunohistochemistry, endocytosis, and ultrastructure, etc. Kupffer cells were incubated with triglyceride (25 micrograms/ml) and VLDL (25 micrograms/ml) for 24 hours, KCCM were prepared, and MTT colorimetric assay was detected for HSC proliferation. RESULTS: HSC proliferation was 0.1894 +/- 0.0316 (12.5 micrograms/ml), 0.1637 +/- 0.0243 (25 micrograms/ml), 0.1450 +/- 0.0264 (50 micrograms/ml), 0.1212 +/- 0.0275 (100 micrograms/ml), 0.1226 +/- 0.0138 (200 micrograms/ml) and 0.0990 +/- 0.0163 (400 micrograms/ml) in the presence of triglyceride and was 0.1583 +/- 0.0314 (6.25 micrograms/ml), 0.1642 +/- 0.0269 (12.5 micrograms/ml), 0.1834 +/- 0.0498 (25 micrograms/ml), 0.1964 +/- 0.0287 (50 micrograms/ml) and 0.2202 +/- 0.0284 (100 micrograms/ml) in presence of VLDL, respectively. Compared with the control, HSC proliferation at 400 micrograms/ml of triglyceride was lower (P < 0.01), but at 12.5 micrograms/ml of triglyceride and 25, 50, 100 micrograms/ml of VLDL higher (P < 0.05 or 0.01); HSC proliferation was 0.1569 +/- 0.0144, 0.1924 +/- 0.0113 and 0.1871 +/- 0.0116 in the presence of KCCM, KCCM + triglyceride and KCCM + VLDL, respectively. Compared with the control and KCCM, KCCM + triglyceride and KCCM + VLDL might promote HSC proliferation (P < 0.01); there was no statistical significance between KCCM + triglyceride and KCCM + VLDL (P > 0.05); KCCM was greater in HSC proliferation than the control, but there was no significant change (P > 0.05). CONCLUSIONS: Triglyceride, VLDL, and KCCM stimulated by triglyceride and VLDL might promote HSC proliferation and be associated with fatty liver and hepatic fibrogenesis.

Animals↗

PubMed1999

[Effects of Kupffer cells stimulated by triglyceride and very low-density lipoprotein on proliferation of rat hepatic stellate cells].

OBJECTIVE: To study the effects of Kupffer cell-conditioned medium (KCCM) derived from triglyceride and very low-density lipoprotein (VLDL) treatment on proliferation of rat hepatic stellate cells (HSC). METHODS: HSC and Kupffer cells were isolated from liver of Wistar rats by in situ perfusion with pronase and collagenase and density gradient centrifugation with Nycodenz and then cultured. KCCM was prepared and MTT colorimetric assay was used to detect HSC proliferation. RESULTS: HSC and Kupffer cells were isolated successfully with high purity. 12.5 mg/L of triglyceride and 25 - 100 mg/L of VLDL promoted HSC proliferation (P < 0.05 or 0.01); KCCM + triglyceride and KCCM + VLDL might promote HSC proliferation as compared with a control group (P < 0.01). There was no significant difference between KCCM + triglyceride and KCCM + VLDL (P > 0.05). CONCLUSION: The technique for isolation of HSC and Kupffer cells described here is simple and reliable. Triglyceride, VLDL and KCCM stimulated by them may promote HSC proliferation and be associated with fatty liver and hepatic fibrogenesis.

Animals↗

PubMed1998

Ethylene responses are negatively regulated by a receptor gene family in Arabidopsis thaliana.

A family of genes including ETR1, ETR2, EIN4, ERS1, and ERS2 is implicated in ethylene perception in Arabidopsis thaliana. As only dominant mutations were previously available for these genes, it was unclear whether all of them are components in the ethylene signaling pathway and whether they code for positive or negative regulators of ethylene responses. In this study, we have isolated loss-of-function mutations of four of these genes (ETR1, ETR2, EIN4, and ERS2) and identified an ethylene-independent role of ETR1 in promoting cell elongation. Quadruple mutants had constitutive ethylene responses, revealing that these proteins negatively regulate ethylene responses and that the induction of ethylene response in Arabidopsis is through inactivation rather than activation of these proteins.

Arabidopsis↗

PubMed1998

ETR2 is an ETR1-like gene involved in ethylene signaling in Arabidopsis.

The plant hormone ethylene regulates a variety of processes of growth and development. To identify components in the ethylene signal transduction pathway, we screened for ethylene-insensitive mutants in Arabidopsis thaliana and isolated a dominant etr2-1 mutant. The etr2-1 mutation confers ethylene insensitivity in several processes, including etiolated seedling elongation, leaf expansion, and leaf senescence. Double mutant analysis indicates that ETR2 acts upstream of CTR1, which codes for a Raf-related protein kinase. We cloned the ETR2 gene on the basis of its map position, and we found that it exhibits sequence homology to the ethylene receptor gene ETR1 and the ETR1-like ERS gene. ETR2 may thus encode a third ethylene receptor in Arabidopsis, transducing the hormonal signal through its "two-component" structure. Expression studies show that ETR2 is ubiquitously expressed and has a higher expression in some tissues, including inflorescence and floral meristems, petals, and ovules.

Amino Acid Sequence↗

PubMed1998

DNA repair enhancement by a combined supplement of carotenoids, nicotinamide, and zinc.

Four volunteers were involved for 5 weeks of a baseline period, followed by 7 weeks of a combined supplementation of nicotinamide, zinc, and carotenoids (Nicoplex). Blood sampling and bioassays were carried out every week during the evaluation period. The supplementation of Nicoplex resulted in statistically significant increased resistance to DNA single-strand breaks induced by H2O2 (DNA retained on filter % from 46.7 +/- 1.9 to 59.4 +/- 4.3; p < 0.01), increased DNA repair 60 min after induction of damage (DNA retained on filter % from 74.6 +/- 4.8 to 88.3 +/- 4.2; p < 0.01), elevated poly (ADP-ribose) polymerase (PARP) activity (p < 0.05), and an increased proliferative response to phytohemagglutinin (PHA) (p < 0.05) when compared with the levels before supplementation. However, when the same subjects were supplemented with nicotinamide, zinc, and carotenoids together with another 17 nutrients or minerals, there were no changes in DNA damage, DNA repair, or proliferative response to PHA. Through the use of a rat model, DNA repair of splenocytes 3 h after 12 Gy whole-body irradiation was significantly enhanced in rats supplemented with Nicoplex for 6 weeks (p < 0.05) and 8 weeks (p < 0.01). Comparison of Nicoplex and its components administered separately revealed that there was an additive effect on DNA repair for both single- and double-strand breaks (both p < 0.05). On the basis of the results, it is hypothesized that the enhanced effect of combined supplement of nicotinamide, zinc, and carotenoids on DNA repair depends on their diversified mechanisms of action while multinutrient supplementation may compromise the effects by inhibitory interactions including uptake and absorption.

Adult↗

PubMed1998

EIN4 and ERS2 are members of the putative ethylene receptor gene family in Arabidopsis.

The Arabidopsis ethylene receptor gene ETR1 and two related genes, ERS1 and ETR2, were identified previously. These three genes encode proteins homologous to the two-component regulators that are widely used for environment sensing in bacteria. Mutations in these genes confer ethylene insensitivity to wild-type plants. Here, we identified two Arabidopsis genes, EIN4 and ERS2, by cross-hybridizing them with ETR2. Sequence analysis showed that they are more closely related to ETR2 than they are to ETR1 or ERS1. EIN4 previously was isolated as a dominant ethylene-insensitive mutant. ERS2 also conferred dominant ethylene insensitivity when certain mutations were introduced into it. Double mutant analysis indicated that ERS2, similar to ETR1, ETR2, ERS1, and EIN4, acts upstream of CTR1. Therefore, EIN4 and ERS2, along with ETR1, ETR2, and ERS1, are members of the ethylene receptor-related gene family of Arabidopsis. RNA expression patterns of members of this gene family suggest that they might have distinct as well as redundant functions in ethylene perception.

Amino Acid Sequence↗

PubMed1998

Improving the success of culturing Helicobacter pylori from gastric biopsies.

Factors influencing the successful isolation of Helicobacter pylori from human gastric biopsies were studied. Within 24 h, each of the gastric biopsies was inoculated onto chocolate blood agar media and incubated for up to 2 weeks. Among 63 (70%) culture positive cases in 90 patients, 58 (64%) cases were culture positive for both specimens, while five (6%) cases were culture positive in only one biopsy. Of the 63 positive cultures, 51 H. pylori strains (81%) grew on both media with and without antibiotics. Eight strains (13%) grew only on medium without antibiotics, while four isolates (6%) were obtained only from medium with antibiotics. These results support the previous histological observation of patchy colonization of H. pylori in the stomach. The success rate for culture of H. pylori from gastric biopsies increased when two biopsies were taken and inoculated on chocolate blood agar media with and without antibiotics.

Helicobacter Infections↗

PubMed1998

Requirement for matrix metalloproteinase-9 (gelatinase B) expression in metastasis by murine prostate carcinoma.

Although a number of effective therapies are available for localized prostate cancer, metastatic prostate cancer is difficult to treat and impossible to cure. Identification of the gene products that enable a prostatic carcinoma cell to metastasize should facilitate an understanding of the processes leading to metastasis. To characterize the contribution of matrix metalloproteinase-9 (MMP-9, gelatinase B or the 92-kd type IV gelatinase/collagenase) to the development of metastasis in prostate cancer, we reduced MMP-9 expression in metastatic murine prostatic carcinoma cells using a ribozyme. The ribozyme transfected cells had lower basal levels of MMP-9 as well as decreased levels after stimulation by transforming growth factor-beta or phorbol 12-myristate 13-acetate when compared with the parental cells or with control transfectants. The cells with down-regulated MMP-9 were unable to form lung colonies in the experimental metastasis assay, whereas the controls and parental cells readily formed metastases. All cell types readily formed tumors after injection and down-regulation of MMP-9 did not adversely affect the rate of tumor growth. Thus, MMP-9 expression is required for hematogenous metastasis in a murine prostate model system raising the possibility that it may play an equivalent role in human prostate cancer.

Animals↗

PubMed1998

Apolipoprotein B signal peptide and apolipoprotein E genotypes as determinants of the hepatic secretion of VLDL apoB in obese men.

We aimed to examine the effect of genetic polymorphisms of apolipoprotein B-100 (apoB) signal peptide and apolipoprotein E (apoE) on the hepatic secretion of very low density lipoprotein (VLDL) apoB in 29 men with visceral obesity. We studied apoB secretion using a primed (1 mg/kg), constant (1 mg/kg/h) intravenous infusion of [1-(13)C]leucine. The isotopic enrichment of VLDL apoB was determined using gas chromatography-mass spectrometry (GCMS). A multi-compartmental model was used to estimate the fractional turnover rate of VLDL apoB. Genotypes for the apoB signal peptide length polymorphism, 27 amino acid (SP27) and 24 amino acid (SP24), and apoE genotypes were determined using polymerase chain reaction. In subjects who were not apoE2 carriers and were homozygous for the SP27 of the apoB signal peptide, the hepatic secretion of VLDL apoB was significantly higher than in subjects who were not apoE2 carriers and were either heterozygous or homozygous for the SP24 allele (31.3 +/- 11.8 mg/kg fat-free mass/day, n = 8 vs. 16.9 +/- 12.2 mg/kg fat-free mass/day, n = 13, P = 0.01). In subjects who were not apoE4 carriers and were either heterozygous or homozygous for the apoB SP24 allele, the hepatic secretion of VLDL apoB was significantly lower than in subjects who were not apoE4 carriers and were homozygous for the SP27 allele (15.8 +/- 12.9 mg/kg fat-free mass/day, n = 13 vs. 27.4 +/- 11.5 mg/kg fat-free mass/day, n = 7, P = 0.03). The data suggest that in men with visceral obesity, the apoB signal peptide and apoE genotypes appear to be involved in the hepatic secretion of apoB.

Adult↗

PubMed1998

Characterization of clinical isolates of Helicobacter pylori in Singapore.

Of the 69 Helicobacter pylori isolates analysed, 31 strains (45%) showed resistance to metronidazole, one strain (1.4%) was resistant to amoxicillin while two strains (2.9%) were resistant to clarithromycin. It was found that metronidazole resistance rates increased in Singapore from 20% to 62% between late 1995 and early 1997. By biotyping using API ZYM, a total of 80% (55/69) strains were characterized as biotype II, while the remaining 20% (14/69) strains belonged to biotype III. Interestingly, 71% (10/14) of biotype III were resistant to metronidazole compared with 38% (21/55) of biotype II. DNA profiles generated by random amplified polymorphic DNA from 69 isolates showed highly diversified DNA fingerprints allowing effective discrimination among strains. Of the 60 H. pylori isolates from peptic ulcer patients, it was found that cagA and vacA occurred in 80% (48/60) and 82% (49/60) isolates, respectively.

Amoxicillin↗

PubMed1997

Neutral metoclopramide sensitizes cytotoxicity induced by ionizing radiation in SCID mice xenografted with a human brain astrocytoma.

A formulation of metoclopramide (MCA) conformationally altered by neutralization of pH (nMCA, Neu-Sensamide) has been shown to have the same efficacy of enhancing the cytotoxicity of a single dose of 1 Gy radiation as acidic formulations (e.g., Primperan, Sensamide) in a human lung adenocarcinoma (H2981) xenografted into SCID mice. In the present study, 2 x 1 Gy radiation was combined with 2 x 2 mg nMCA/kg body weight injected 2 hr before radiation treatment for evaluation of radiosensitization in SCID mice xenografted with a human brain astrocytoma (T24). Given in this treatment schedule, nMCA alone at 2 mg/kg showed no cytotoxic effect on tumor growth in vivo. When combined with 2 x 1 Gy of radiation, however, the cytotoxicity was significantly increased as measured by tumor growth delay over the radiation-only-treated group. Furthermore, nMCA was absorbed into brains of mice and rats as efficiently as acidic MCA (aMCA) when analyzed 45 min after i.m. injection by high-performance liquid chromatography.

Animals↗

PubMed1997

Identification of regions in HIV-1 Nef required for efficient downregulation of cell surface CD4.

Downregulation of cell surface CD4 is a characteristic property of all lentiviral Nef proteins. We have used mutational analysis to define regions within HIV-1 Nef that are critical for this biological activity. Two discontinuous regions in Nef, extending approximately from residues 96 to 144 and from residues 175 to 186, are reported to be essential for efficient CD4 downregulation. Interestingly, these sequences coincide with two conserved regions of the Nef protein that are juxtaposed to form a single surface on the known structure of Nef. A third, more amino terminal conserved region in Nef, previously reported to be important for Nef enhancement of virion infectivity, was found to be largely dispensable for CD4 downregulation. These data raise the possibility that Nef may contain two structurally distinct functional domains, only one of which contributes to the CD4 downregulation phenotype.

Amino Acid Sequence↗

PubMed1997

Quantitative polymerase chain reaction for the detection of Helicobacter pylori in gastric biopsy specimens.

A variety of methods, including the polymerase chain reaction (PCR), are available for the detection of Helicobacter pylori in clinical samples, but none of them can adequately quantify the organism. In the present study, the competitive PCR, a rapid and simple method for quantification of Helicobacter pylori DNA in gastric biopsies, was used to measure the amount of DNA present in Helicobacter pylori-positive biopsies. This method is based on coamplification of an internal standard and a target DNA sequence with one set of primers. The internal standard was prepared using a nonhomologous fragment of DNA ligated to specific primers used to amplify the target DNA. This competitive DNA fragment of a desired size and containing primer templates is called a PCR MIMIC. To perform a quantitative PCR, PCR amplification reactions were spiked with known quantities of PCR MIMICs containing unknown amounts of DNA from Helicobacter pylori-positive biopsies. The amount of target DNA was determined by visual comparison of the PCR products after establishment of the correlation between the internal control concentration and the DNA concentration in a competitive amplification reaction. The results were confirmed by a radioactive method. Quantitative PCR can be a reliable method for determining the extent of Helicobacter pylori infection.

Biopsy↗