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Biomedical subjects

H Long

Publications and source records attributed to H Long.

At least 19 recordsLinked to original sources
PubMed2005

Identification of LMW glutenin-like genes from Secale sylvestre host.

Three low-molecular-weight (LMW) glutenin-like genes (designated as Ssy1, Ssy2 and Ssy3) from Secale sylvestre Host were isolated and characterized. The three genes consist of a predicted highly conservative signal peptide with 20 amino acids, a short N-terminal region with 13 amino acids, a highly variable repetitive domain and a less variable C-terminal domain. The deduced amino acid sequences of the three genes were the LMW-m type due to a methionine residue at the N-terminus. The phylogenic analysis indicated that the prolamin genes could be perfectly clustered into five groups, including HMW-GS, LMW-GS, alpha/beta-, gamma- and omega-prolamin. The LMW glutenin-like genes of S. sylvestre were more orthologous with the LMW-GS genes of wheat and B hordein genes of barley, which also had been confirmed by the homology analysis with the LMW-GS of wheat at Glu-A3, Glu-B3 and Glu-D3 loci. These results indicated that a chromosome locus (designated as Glu-R3) might be located on the R genome of S. sylvestre with the functions similar to the Glu-3 locus in wheat and its related species.

Amino Acid Sequence↗
PubMed2003

The effects of Mycobacterium vaccae on allergen-induced airway responses in atopic asthma.

T-helper (Th)2 cytokines play a central role in asthma. Therefore, a double-blind randomised study was conducted to investigate whether heat-killed Mycobacterium vaccae (SRL172), a potent downregulator of Th2 cytokines, can reduce allergen-induced airway responses in patients with atopic asthma. A total 24 male asthmatics participated in this study. A bronchial allergen challenge was performed along with early (EAR) and late asthmatic responses (LAR) 2 weeks before and 3 weeks after a single intradermal injection of SRL172 or placebo. Before and after treatment, serum immunoglobulin (Ig)E levels and in vitro production of interleukin (IL)-5 by peripheral blood lymphocytes were studied. Neither treatment affected the EAR. SRL172 caused a mean 34% reduction of the area under the curve of the forced expiratory volume in one second (FEV1) changes during the LAR, which failed to reach conventional statistical significance when compared with placebo. SRL172 also caused a mean 25% decrease in the maximum fall in FEV1 during LAR, but this was not significantly different from placebo. SRL172 caused a reduction in serum IgE and IL-5 synthesis in vitro 3 weeks post-treatment (p = 0.07). This study shows a trend toward significance for the effects of heat-killed Mycobacterium vaccae (SRL172) on allergen-induced airway responses. Further clinical trials, involving multiple dosing, are needed.

Adult↗
PubMed2001

Liquid chromatography with multi-channel electrochemical detection for the determination of epigallocatechin gallate in rat plasma utilizing an automated blood sampling device.

A liquid chromatography method with multi-channel electrochemical detection was developed for the determination of epigallocatechin gallate (EGCG) in rat plasma. After administration of EGCG, blood samples were periodically collected by Culex (an automated blood sampling robot). EGCG was extracted from 50 microl of diluted blood (blood and saline at a ratio of 1:1) with ethyl acetate. Chromatographic separation was achieved within 10 min using a C8 (150x4.6 mm) 5 microm column with a mobile phase containing 20 mM sodium monochloroacetate, pH 2.8 and 12% acetonitrile at a flow-rate of 1.2 ml/min. A four-channel detector with glassy carbon electrodes was used with applied potentials of +700, 600, 500, 400 mV vs. Ag/AgCl. The limit of detection was 2 ng/ml at a signal-to-noise ratio of 3:1 and the limit of quantitation was 5 ng/ml. The calibration curve was linear over the range of 5-800 ng/ml. The intra- and inter-assay precisions were in the range of 1.3-4.5% and 2.2-4.4%, respectively. Using this method it was possible to determine plasma concentration following a single dose of EGCG to rats with good accuracy and precision. Thus the pharmacokinetic properties of EGCG in rats can be examined for intravenous, intraperitoneal and oral dosing.

Animals↗
PubMed2001

Expression of Clostridium perfringens enterotoxin receptors claudin-3 and claudin-4 in prostate cancer epithelium.

The mRNA for Rvp.1 (rat ventral prostate) increases in abundance before gland involution after androgen deprivation. Rvp.1 is homologous to CPE-R, the high-affinity intestinal epithelial receptor for Clostridium perfringens enterotoxin (CPE), and is sufficient to mediate CPE binding and trigger subsequent toxin-mediated cytolysis. Rvp.1 (claudin-3) and CPE-R (claudin-4) are members of a larger family of transmembrane tissue-specific claudin proteins that are essential components of intercellular tight junction structures regulating paracellular ion flux. However, claudin-3 and claudin-4 are the only family members capable of mediating CPE binding and cytolysis. The present study was designed to study the expression of claudin-3 and claudin-4 in human prostate tissue as potential targets for CPE toxin-mediated therapy for prostate cancer. On human multiple-tissue Northern blot analysis, mRNAs for both claudin-3 and claudin-4 were expressed at high levels in prostate tissue. In normal prostate tissue, expression of claudin-3 was localized exclusively within acinar epithelial cells by in situ mRNA hybridization. Compared with expression within prostate epithelial cells in surrounding normal glandular tissue, expression of claudin-3 mRNA remained high in the epithelium of prostate adenocarcinoma (10 of 10) and prostatic intraepithelial neoplasia (five of five). Prostate adenocarcinoma cells metastatic to bone were obtained from a patient with disease progression during antiandrogen therapy. These metastatic cells were prostate-specific antigen-positive by immunohistochemical staining and also expressed functional CPE receptors as measured by sensitivity to CPE-induced cell lysis. The persistent high level of claudin-3 expression in prostate adenocarcinoma and functional cytotoxicity of CPE in metastatic androgen-independent prostate adenocarcinoma suggests a new potential therapeutic strategy for prostate cancer.

Adenocarcinoma↗
PubMed2001

Oxidative preconditioning and apoptosis in L-cells. Roles of protein kinase B and mitogen-activated protein kinases.

Oxidative stress can cause significant cell death by apoptosis. We performed studies in L-cells to explore whether prior exposure to oxidative stress ("oxidative preconditioning") can protect the cell against the apoptotic consequences of subsequent oxidative insults and to establish the mediators in the preconditioning signaling cascade. Cells were preconditioned with three 5-min exposures to H(2)O(2), followed by 10-h recovery and subsequent exposure to 600 microm H(2)O(2) for 10 h. A single 10-h exposure to H(2)O(2) induced substantial apoptotic cell death (approximately 90%), as determined by enzyme-linked immunosorbent assay, TUNEL (terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling), and Annexin V methods, but apoptosis was largely prevented in preconditioned cells. The degree of cytoprotection depended on the strength of preconditioning or H(2)O(2) concentration (20 approximately 600 microm). Transient increases in mitogen-activated protein kinase (MAPK), p38, and JNK/SAPK activities and sustained protein kinase B (Akt) activation, accompanied by drastically reduced caspase 3 activity, were seen after preconditioning. The expression levels of these kinases were unaltered. Inhibitors of p38 (SB203580) and phosphoinositide 3-kinase (PI3K, LY294002) pathways abolished the protection provided by preconditioning. We conclude that oxidative preconditioning protects cells against apoptosis and that this effect involves MAPK and PI3K/Akt pathways. This system may be important in regulating apoptotic cell death in development and disease states.

Animals↗
PubMed2001

Expression and isolation of antimicrobial small molecules from soil DNA libraries.

Natural products have been a critically important source of clinically relevant small molecule therapeutics. However, the discovery rate of novel structural classes of antimicrobial molecules has declined. Recently, increasing evidence has shown that the number of species cultivated from soil represents less than 1% of the total population, opening up the exciting possibility that these uncultured species may provide a large untapped pool from which novel natural products can be discovered. We have constructed and expressed in E. coli a BAC (bacterial artificial chromosome) library containing genomic fragments of DNA (5-120kb) isolated directly from soil organisms (S-DNA). Screening of the library resulted in the identification of several antimicrobial activities expressed by different recombinant clones. One clone (mg1.1) has been partially characterized and found to express several small molecules related to and including indirubin. These results show that genes involved in natural product synthesis can be cloned directly from S-DNA and expressed in a heterologous host, supporting the idea that this technology has the potential to provide novel natural products from the wealth of environmental microbial diversity and is a potentially important new tool for drug discovery.

Amino Acid Sequence↗
PubMed2000

Liquid chromatography with multichannel electrochemical detection for the determination of trans-resveratrol in rat blood utilizing an automated blood sampling device.

A sensitive and selective multichannel liquid chromatography-electrochemistry method was developed for the determination of the natural product trans-resveratrol (resveratrol) in rat blood. After administration of resveratrol, blood samples were periodically collected by an automated blood sampling device. Resveratrol was extracted from 150 microl of diluted blood (blood and saline at a ratio of 1:1) with acetonitrile containing 1% of trichloroacetic acid. Chromatographic separation was achieved within 12 min using a C18 (100x2.0 mm) 3 microm column with a mobile phase containing 20 mM sodium acetate, 0.5 mM EDTA, pH 4.5 and 21% acetonitrile at a flow-rate of 0.4 ml/min. A multichannel detector with glassy carbon electrodes was used, which can control up to four working electrodes simultaneously with applied potentials of +800, 700, 600, 500 mV vs. Ag/AgCl. The limit of detection was 2 ng/ml at a signal-to-noise ratio of 3:1 and the limit of quantitation was 4 ng/ml. The linearity of the calibration curve was obtained over the analytical range of 5-1000 ng/ml. The intra- and interassay precision was in the range of 2.5-4.4% and 1.2-4.3%, respectively. Using this method it was possible to quantify blood concentration following a single dose of resveratrol to rats with good accuracy and precision. Thus the pharmacokinetic properties of resveratrol in rats can be examined for intraperitoneal, oral and intravenous dosing.

Animals↗
PubMed2000

Ceramides induce apoptosis in HeLa cells and enhance cytochrome c-induced apoptosis in Xenopus egg extracts.

Ceramide has been reported to induce typical apoptotic changes in nuclei incubated in a cell-free system, and that the addition of ceramide bypasses the requirement for mitochondria. Here, we explore the possible pathways by which ceramide induces apoptosis either in intact cells or in a cell-free system which we have developed. We found that in the cell-free system, C2-ceramide is not able to induce apoptosis in nuclei whereas cytochrome c does, but it is able to induce HeLa cells to undergo apoptosis. Ceramide is also not able to induce apoptosis when added into the cell-free system together with purified mitochondria. Further investigation showed that C2-ceramide at certain concentrations greatly increases nuclear apoptosis caused by cytochrome c in the cell-free system. From these results we conclude that the induction of apoptosis by ceramide may require intact cells in which some unknown signal transduction pathways are involved.

Animals↗
PubMed2000

Health promotion and older people: the role of the general practitioner in Australia in promoting healthy ageing.

OBJECTIVE: The Commonwealth Government's Enhanced Primary Care initiative supports measures to enhance the role of general practitioners (GPs) in promoting healthy ageing as part of a population health approach. This paper comments on how the health assessments can be conducted to best effect, to strengthen the role of GPs in primary care and to promote autonomy and independence in older people. METHOD: The relevant literature was collated to produce a review of public health and health promotion approaches and to ascertain the effectiveness of health promotion interventions for older people. A broad definition of health promotion including primary, secondary and tertiary prevention was adopted. RESULTS: The evidence base suggests there is scope for greater targeting of health promotion activities towards older people. The rationale for the Australian GP to assume a major health promotion role with their older patients is provided. Associated barriers and enablers are discussed. CONCLUSIONS: Prevention of disability is a key public health issue. The new MBS items may enable systematic evaluation of function and assist healthy ageing for all older people, including the frail aged. An increase in the preventive advice given to older patients has the potential to increase healthy behaviours and alter health outcomes. IMPLICATIONS: The annual health assessment items on the Medicare Benefits Schedule, by enabling the GP to focus on prevention and coordination of care, have the potential to improve the health, physical, psychological and social function of older Australians.

Aged↗
PubMed1999

[Purity analysis of cephalosporins with capillary zone electrophoresis].

A capillary zone electrophoresis method is proposed for the purity determination of nine cephalosporin drugs. A background electrolyte comprising of either 20 mmol/L pH 9.20 borate buffer or 20 mmol/L pH 6.86 phosphate buffer was used for most drugs studied except for cefaloridine which formed neutral molecules at these pH values. For it 50 mmol/L pH 2.05 phosphate buffer was used instead. Internal normalization method was employed for quantitation. The method is simple, rapid and versatile. Analysis was completed within 8 min. The merits and limitations of the method were also discussed.

Cefazolin↗
PubMed1998

Expression and chromosomal localization of the Requiem gene.

Apoptosis in murine myeloid cell lines requires the expression of the Requiem gene, which encodes a putative zinc finger protein. We detected the protein in both cytoplasmic and nuclear subcellular fractions of murine myeloid cells and human K562 leukemia cells, which suggests that the protein might have a function distinct from a transcription factor. This distribution did not alter upon apoptosis induction by IL-3 deprivation. As an approach to investigate its role in development, we determined the spatio-temporal expression pattern in the mouse. Expression was detected in various tissues in earlier gestational age; however, confined to testes, spleen, thymus, and part of the hippocampus in the adult mouse. The expression profile is consistent with a functional role during rapid growth and cell turnover, and in agreement with a regulatory function for hematopoietic cells. The human cDNA clone sequenced showed high homology to its murine counterpart and extended the open reading frame by 20 codons upstream. The gene is located in the proximal region of mouse Chromosome (Chr) 19. In the homologous human region at 11q13, it is located at about 150 kb centromeric from MLK3.

Amino Acid Sequence↗
PubMed1998

Osteoprogenitor cells as targets for ex vivo gene transfer.

We transduced osteoprogenitor cells with recombinant retrovirus and analyzed proviral integration patterns into chromosomal DNA to detect for the first time the clonal and cellular fate of osteoprogenitor-derived progeny cells. Metaphyseal bone cells and diaphyseal stromal cells were isolated from the distal femurs of young rats, transduced with the vM5neolacZ recombinant retrovirus, and selected in the neomycin analog, G418. Following surgical marrow ablation of a femur in one leg of mature rats, retroviral-transduced metaphyseal or diaphyseal cells were injected into the ablated site. These rats were killed 5-6 days later. Metaphyseal and diaphyseal cells were isolated from distal femurs, selected in G418, and stained for beta-galactosidase (beta-gal+). The number and clonal origin of transduced progenitor cells were determined. High numbers of beta-galactosidase colonies with an osteoblast phenotype were obtained following metaphyseal transplants and detected in 100% of metaphyseal and none of diaphyseal specimens. In contrast, beta-galactosidase colonies derived from diaphyseal transplants were detected in 50% of specimens in both the metaphysis and diaphysis, and the absolute number of progenitor cell colonies was 60-fold less than metaphyseal transplants. Provirus was only detected in the ablated bones and not in the contralateral bone or other tissues. Proviral integration fragment analysis showed a single integration site for recovered metaphyseal cell clones, consistent with their origination from a common single progenitor. This is one of the first demonstrations of successful transplantation of clonal osteoprogenitors to their site of origin in bone. It may be possible to use these cells to target genes to bone for therapeutic use in skeletal and hematopoietic diseases.

Animals↗
PubMed1998

Predicting and preventing pressure ulcers in adults with paralysis.

A questionnaire mailed to all 2,295 members of the Eastern Paralyzed Veterans Association measured 45 potential risk factors for pressure ulcers. Logistic-regression analysis and Cox proportional-hazards analyses were used to identify the variables that were independently associated with pressure ulcers. The survey response rate was 42.2%. Among 15 risk factors from a previously published scale by the authors, 7 were independent predictors of pressure ulcer development: level of activity, level of mobility, complete spinal cord injury, urine incontinence or moisture, autonomic dysreflexia, pulmonary disease, and renal disease. In addition, 2 new variables added significant predictive value: being prone to infections that cause breathing problems and paralysis caused by trauma (as opposed to disease). Using these 9 risk factors, a new pressure ulcer risk assessment scale was designed specifically for persons with paralysis who are living in a community setting. It appears to be a more accurate method of predicting pressure ulcers than currently used risk assessment scales.

Adult↗
PubMed1998

[Effects of specific removal of circulating tumor necrosis factor-alpha by immunoadsorption on nitric oxide in endotoxin shock].

OBJECTIVES: To evaluate the effects of specific removal of circulating TNF-alpha by immunoadsorption on nitric oxide (NO) in endotoxin shock. METHODS: Immunoadsorbent against TNF-alpha was produced by the attachment of anti-TNF-alpha monoclonal antibody (McAb) to agarose beads. Blank columns were made of agarose beads without the attachment of anti-TNF-alpha McAb. New Zealand white rabbits were injected intravenously with Lipopolysaccharide (LPS, Escherichia coli O111: B4, 8.0 x 10(9) cfu/kg. B.W), and then were randomly divided into three groups: (1) control group(n = 25); without other treatment. (2) pseudoperfusion group(n = 25): rabbits underwent hemoperfusion through the blank columns. (3) perfusion group (n = 15): rabbits underwent hemoperfusion through the immunoadsorbent columns. Hemoperfusion was started at 1 h after the injection of LPS, and was sustained for two hours with blood flow rate of 5 ml/min. RESULTS: Mean arterial pressure in the perfusion group was significantly increased at 30 min after hemoperfusion (P < 0.05). It maintained a level higher than that before hemoperfusion (P < 0.05), and was higher (P < 0.05) than that in the control and pseudoperfusion groups at 3 h (end of the monitoring period). The plasma TNF-alpha level in the perfusion group was significantly lower than that in the other two groups at 2, 3 and 6 hour after LPS injection (P < 0.05). Although the concentration of plasma nitrite (NO2-, one of the stable end products of NO) in the perfusion group was significantly lower (P < 0.05) than that in the other two groups from 3 h after LPS infusion, it was significantly higher (P < 0.05) than the baseline value from 30 min to 12 h. The activities of NO synthase (NOS) in the heart and lung were significantly lower (P < 0.05) in the perfusion group than in the other two groups at 24 h. The serum levels of alanine transaminase, aspartate transaminase, urea nitrogen, creatinine, lactate dehydrogenase, alpha-hydrobulyric dehydrogenase and alkaline phosphatase in the perfusion group were significantly lower (P < 0.05) than those in the other two groups at 24 h. Moreover, the survival rate of rabbits in the perfusion group was higher (P < 0.05) than that of the other two groups at 24 h. CONCLUSION: Specific removal of circulating TNF-alpha by immunoadsorption actually acts as the selective inhibition of the inducible NOS(iNOS) and may be a new and effective therapy for endotoxin shock.

Animals↗
PubMed1998

[Expression of cell adhesion molecule CD44 variant isoform correlated with the clinical behavior of renal cell carcinoma].

OBJECTIVE: To determinate whether the expression of CD44v in renal cell carcinoma (RCC) is associated with tumor malignant behavior. METHOD: Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect CD44v in 31 human renal cell carcinoma (RCC) in addition to 18 normal renal tissues from patients with non-malignant disease. RESULT: Eighteen RCCs showed positive expression while none of normal renal tissue expressed CD44v (P < 0.001). CD44v was expressed in metastatic or high pathological stage RCC, but the expression of CD44v was not correlated with cellular differentiation. CONCLUSION: Our data indicate that a role for CD44v in human RCC progression and metastases, and CD44v may prove to be a marker for high metastasis potential of RCC.

Adult↗
PubMed1998

Neutrophils and monocytes from subjects with the Mediterranean G6PD variant: effect of Plasmodium falciparum hemozoin on G6PD activity, oxidative burst and cytokine production.

Glucose 6-phosphate dehydrogenase (G6PD) activity and oxidative burst were measured in neutrophils and monocytes from five, hemizygous, G6PD-deficient (Mediterranean variant) individuals and five normal controls. Additionally, tumor necrosis factor (TNF), interleukin-10 (IL-10), interleukin-12 (IL-12) release and phagocytosis of the malarial pigment hemozoin or opsonized erythrocytes (RBC) were measured in monocytes recovered from G6PD-deficient and normal individuals. G6PD activity was significantly lower in "deficient monocytes" (38% residual activity, p = 0.01) and not significantly different in "deficient neutrophils" (79% residual activity, p = 0.83) compared to homologous leukocytes recovered from normal controls. Oxidative burst was not significantly different in "deficient" versus "normal" neutrophils and monocytes. Previous phagocytosis of hemozoin decreased the phorbol ester induced oxidative burst in "deficient" and "normal" monocytes but not in neutrophils. Phagocytosis of hemozoin and RBC strongly stimulated cytokine production. With the exception of IL-10, the cytokine production pattern was comparable in "deficient" versus "normal" cells. Incubation with high concentrations of hemozoin (equivalent to 300 RBC per monocyte) strongly stimulated TNF production. Lipopolysaccharide (LPS) had an additive effect on TNF production induced by hemozoin or opsonized RBC. IL-12 production was induced only by the presence of large amounts of hemozoin. IL-10 production was increased in normal monocytes incubated with RBC or hemozoin. LPS increased IL-10 production significantly in monocytes incubated with RBC or low amounts of hemozoin (equivalent to 30 RBC per monocyte), but had no effect when given alone or in conjunction with high concentrations of hemozoin. Interestingly, deficient monocytes produced less IL-10 than normal cells under these conditions. In conclusion, except for IL-10 production, we did not find major functional differences between neutrophils and monocytes from individuals with or without the Mediterranean G6PD mutation.

Animals↗
PubMed1997

Stimulus responses and amyloid precursor protein processing in DAMI megakaryocytes.

Platelets, when released as anuclear cells by their precursor megakaryocytes, already carry soluble proteolytic fragments of the amyloid precursor protein (APP) within their alpha-granules and intact APP in the alpha-granule membranes. In response to activation signals elicited by physiologic stimuli such as thrombin, platelets release their granules' soluble contents and translocate granule membrane-bound proteins to the plasma membrane. Because platelets carry >90% of the circulation's APP, activated platelets have been implicated as origins of the beta-amyloid peptide fragment of APP (A beta), whose deposition in the cerebrovasculature is characteristic of Alzheimer's disease. We have therefore studied the APP contents and proteolytic processing in resting DAMI human megakaryocytic cells, along with the consequences of the activation of these cells by thrombin, comparing the results in each case to those with human platelets. Resting and PMA-differentiated DAMI cell contents were examined by Western blotting, immunoprecipitation, or metabolic labeling with sulfur 35-labeled methionine during culture, while plasma membrane-bound APP was evaluated by flow cytometry. Activation was followed by changes in cytoplasmic calcium concentration ((Ca++)in) and in membrane potential. Like platelets, DAMI cells exhibited a thrombin dose-dependent delta(Ca++)in, and membrane potential change; in contrast to the surface of a platelet, the surface of an agranular resting DAMI cell expresses granule-membrane proteins (APP and CD63) that appear on platelets only after activation. DAMI cell culture with 35S-labeled methionine confirmed that megakaryocytes synthesize large amounts of APP, of slightly higher molecular weight, and degrade their APP extensively before platelets are formed.

Amyloid beta-Protein Precursor↗