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Biomedical subjects

H Ma

Publications and source records attributed to H Ma.

At least 163 records · Page 9Linked to original sources
PubMed1998

[A study of genetic heterogeneity in Pfeiffer syndrome].

OBJECTIVE: To understand the molecular pathology of Pfeiffer syndrome. METHODS: DNA from peripheral blood was examined in 4 families with Pfeiffer syndrome by SSCP-sequence analyses and PCR-restriction enzyme digestion. RESULTS: The authors found the mutations of FGFR2 gene in two families, an A to G transition in the 3' acceptor splice site of intron 8 in a family, and Asp321 Ala substitution in exon 9 in another family. In addition, the mutation in exon 5 of FGFR1 gene (Pro252Arg) was found in a family. CONCLUSION: These findings reveal the genetic heterogeneity of Pfeiffer syndrome and can help one understand the molecular mechanism of the disease.

Acrocephalosyndactylia↗
PubMed1998

[Association between angiotensin II type I receptor gene and human essential hypertension].

OBJECTIVE: To determine whether the angiotensin II type I receptor gene might be implicated in human essential hypertension. METHODS: This was a case-control study on hypertension and normal blood pressure in Chinese DNA abstracted samples from 51 cases of essential hypertension and 74 normal controls were analysed by polymerase chain reaction,digestion of restriction enzyme and electrophesis. RESULTS: The genotype frequency of 1166A/1166C was 0. 196 (10/51) in the essential hypertension group, 0.081 (6/74) in the control group. The genotype frequency of 1166C/1166C was 0 in both groups. The gene frequency of 1166C was 0.098 in the essential hypertension group, 0.041 in the controls. There was a significant increase in allelic frequency of 1166C in hypertension. CONCLUSION: The results indicate that the increase in allelic frequency of 1166C is a risk factor and hence suggest that the change in the angiotensin II type I receptor gene is associated with essential hypertension.

Adolescent↗
PubMed1998

Characterization of N-(Nitrosomethyl)urea in Nitrosated Fermented Fish Products.

To characterize chemical carcinogens in acidic-nitrosated fish sauce sample, N-nitrosamides in the sample were separated by two kinds of reversed-phase HPLC columns, and with detection by photolysis-pyrolysis-thermal energy analyzer. A strong chromatographic peak at t(R) 12 or 4.5 min, same as that for N-(nitrosomethyl)urea (NMU), was obtained on PRP-1 or C(18) HPLC column from fish sauce sample with 10 mM trifluoroacetic acid as the basic mobile; acetonitrile, as organic modifier after the sample was nitrosated by 5 mmol/L of sodium nitrite (final concentration) at 37 degrees C and pH 2.0 for 1 h. No response above t(R) could be observed from the nitrosated sample in the detection system without photolysis. Such a peak could not be obtained from the unnitrosated fish sauce either. These results indicated that the component was NMU. Furthermore, this component, NMU, could also be detected in the nitrosated human gastric juice sample spiked with fish sauce. The formation of NMU in the sample was pH- and nitrite-dependent. This paper provides direct evidence that NMU formation could occur in fish sauce from the high-risk area for stomach cancer and in the fish sauce spiked human gastric juice during nitrosation under simulated gastric conditions.

Journal Article↗
PubMed1998

Antigen is required for the activation of effector activities, whereas interleukin 2 Is required for the maintenance of memory in ovalbumin-specific, CD8+ cytotoxic T lymphocytes.

The mechanisms that maintain memory in T cells are not completely understood. We have investigated the role of antigen and interleukin (IL)-2 in the growth and maintenance of CD8+ T cells using a cytolytic T cell line specific for ovalbumin (OVA)257-264 presented by H-2Kb. This line does not secrete IL-4 or IL-2; hence, stimulation with the OVA-transfected EL4 line (E.G7-OVA) does not induce proliferation without addition of exogenous growth factors. Furthermore, this line can be maintained continuously by weekly addition of irradiated, splenic filler cells and IL-2, with or without E.G7-OVA. Although IL-2 induced proliferation of these cytotoxic T lymphocytes (CTLs), production of interferon gamma and tumor necrosis factor alpha required stimulation of the CTL with E. G7-OVA. The kinetics of lymphokine secretion after stimulation by E. G7-OVA were the same whether the CTL had been maintained with or without antigen (Ag). In addition, both CTL lines killed E.G7-OVA target cells within 4 h. Thus, the effector functions of these CTLs were rapidly induced by T cell receptor (TCR) occupancy. CTLs cultured with or without Ag also served as memory T cells when parked for 100 d in unirradiated, syngeneic recipients without OVA. In the absence of OVA, the precursor frequency was identical in spleens of normal and beta2-microglobulin knockout recipients, but significantly less in IL-2 knockout mice. The decline of memory in the absence of IL-2 supports data from other investigators, suggesting that cell cycling is important to the maintenance of CD8+ T cell memory. These data also suggest that stimulation of OVA-specific CTLs by lymphokines seems to be more important to maintaining memory than stimulation of TCRs by cross-reactive peptides complexed to class I molecules.

Adoptive Transfer↗
PubMed1998

Protein for Lp82 calpain is expressed and enzymatically active in young rat lens.

mRNA for a newly discovered isoform of calpain, termed Lp82, was recently discovered in young rat lens. The purpose of the present experiments was to test for expression of Lp82 protein. Casein zymography after incubation with calcium was used to detect Lp82 proteolytic activity in regions of lenses from young rats. Lp82 protein was detected by immunoblotting or by ELISA after DEAE-5PW chromatography using a polyclonal antibody generated to a peptide sequence in Lp82. Northern blot analysis assessed expression of Lp82 mRNA. Four results demonstrated expression of Lp82 protein; (1) immunoblot reactivity at the predicted molecular mass of 82 kDa, (2) a unique band of calcium-activated lysis in casein zymograms, (3) partial purification and retention of activity from a single Lp82 peak on DEAE-5PW chromatography, and (4) positive immunoblotting and Northern blot analysis only in lens and not in other rat tissues. These results showed that Lp82 protein is lens-preferred, relatively abundant in young rats (especially nucleus), and enzymatically active. Proteolysis of crystallins in the nucleus of young rat lens during normal maturation and cataract formation, formerly attributed solely to m-calpain, may in fact be due to concerted action of both lens Lp82 and ubiquitous m-calpain.

Amino Acid Sequence↗
PubMed1998

A new approach to the development of anti-ischemic drugs: protective drugs against cell injury induced by lysophosphatidylcholine.

Recent studies have revealed that lysophosphatidylcholine (LPC) produces mechanical and metabolic derangements in perfused working rat hearts and Ca2+-overload in isolated cardiac myocytes. Thus, LPC possesses an ischemia-like effect on the heart. Therefore, a drug that possesses an anti-LPC action would protect or improve ischemia/reperfusion damage. We examined the effects of various anti-ischemic drugs on the Ca2+ overload induced by LPC. Our data suggest that a drug with high lipophilicity possesses a protective effect on cell injury induced by LPC, probably because of preservation of membrane integrity.

Adrenergic beta-Antagonists↗
PubMed1998

To be, or not to be, a flower--control of floral meristem identity.

Sexual reproduction in higher plants occurs within the flower, which develops from the floral meristem, a specialized form of lateral meristems. The decision to become a floral meristem is highly regulated, and several genes controlling this process have been isolated. Some of these genes were shown to promote the floral fate precociously and ectopically when expressed constitutively. Furthermore, studies indicate the commitment to the floral fate is not a single switch, but a condition acquired progressively. Finally, genes controlling flowering time, at least in part, act through the floral-meristem-identity genes, and such interactions occur at multiple levels.

Arabidopsis↗
PubMed1998

Identification, sequence analysis and expression studies of novel anther-specific genes of Arabidopsis thaliana.

Relatively little is known about pollen development at the molecular level. For the purpose of gaining understanding of the molecular control of pollen development, a number of Arabidopsis cDNA fragments were isolated using subtractive hybridizations. DNA and RNA hybridizations and sequence analyses indicate that we have isolated cDNAs representing 13 genes. Sequences for 8 of these genes are novel, while those for the remaining 5 genes have substantial similarity to genes previously reported as anther- or pollen-specific. RNA in situ hybridizations with 5 genes revealed that four of them are tapetum-specific with differing temporal expression patterns during pollen development and one is pollen-specific within the flower. Sequence analysis of full-length cDNAs showed that one of the novel genes, ATA7, encodes a protein related to lipid transfer proteins. Another gene, ATA20, encodes a protein with novel repeat sequences and a glycine-rich domain that shares a predicted structure with a known cell wall protein. The full-length ATA27 cDNA encodes a protein similar to the BGL4 beta-glucosidase from Brassica napus. The ATA27 protein is predicted to have an ER retention signal and an acidic isoelectric point, suggesting that it may be localized to the ER lumen. This may be a means of compartmentalization from its substrate(s). Our studies demonstrate that subtractive hybridizations can be used to identify previously unknown genes, which should be valuable tools for further study of pollen and anther development and function.

Amino Acid Sequence↗
PubMed1998

Erythropoietin receptor-operated Ca2+ channels: activation by phospholipase C-gamma 1.

Erythropoietin (EPO) increases Ca2+ influx in vascular smooth muscle cells and acts both as a direct vasoconstrictor and vascular growth factor (that is, angiogenesis). However, the mechanism by which EPO promotes extracellular Ca2+ entry in contractile cells has not been elucidated. In hematopoietic cells, EPO induces tyrosine kinase (TK)-dependent activation of phospholipase C (PLC)-gamma 1 and Ca2+ influx via a voltage-independent Ca2+ conductance. In contractile mesangial cells, we have recently characterized a voltage-independent, 1 pS Ca2+ channel that is dependent on both TK and PLC-gamma 1 activity. Therefore, we examined cultured rat glomerular mesangial cells after timed exposure to recombinant human EPO (20 U/ml). Erythropoietin increased the tyrosine phosphorylation of PLC-gamma 1, promoted membrane complex formation between PLC-gamma 1 and the EPO receptor itself, and raised the levels of intracellular inositol 1,4,5-trisphosphate and intracellular Ca2+. Consistent with our previous studies, 1 pS Ca2+ channel activity was extremely low under basal, unstimulated conditions in cell-attached patches, but was dramatically increased when EPO was present in the patch pipette. Tyrosine kinase inhibition with 100 micron genistein or 1 micron PP1 (Src; selective tyrosine kinase inhibitor) prevented all of these EPO-induced responses. We conclude that: (1) EPO-induced stimulation of 1 pS Ca2+ channels is mediated via a cytosolic Src TK in glomerular mesangial cells. (2) Stimulation of this Ca2(+)-activated, Ca2(+)-permeable channel is dependent on the tyrosine phosphorylation/activation of PLC-gamma 1. (3) This cascade provides a possible mechanism for the vasoconstriction and hypertension observed with clinical EPO use for the treatment of chronic anemias.

Animals↗
PubMed1998

Lp82 calpain during rat lens maturation and cataract formation.

PURPOSE: To measure changes in levels of Lp82 during maturation and selenite cataract formation in rat lens. Lp82 is a lens-specific, calcium-activated isozyme from the calpain family of cysteine proteases (EC 34.22.17). METHODS: Competitive RT-PCR was used to assess Lp82 and m-calpain mRNA concentrations. Immunoblotting and ELISA after DEAE chromatography measured Lp82 and m-calpain protein levels. Casein zymography assessed proteolytic activities in regions and whole lenses from maturing rats. RESULTS: Levels of Lp82 mRNA, protein, and caseinolytic activity decreased more rapidly during maturation of rat lens than for m-calpain. Unexpectedly, the water-insoluble fraction of rat lens contained enzymatically active Lp82. Selenite injection also caused major loss of Lp82 protein during cataract formation. CONCLUSIONS: Lp82 is a proteolytic enzyme likely functioning in early lens development and maturation. The rapid loss of Lp82 activity during lens maturation is probably caused by three factors: autodegradation associated with the proteolysis of soluble and insoluble proteins occurring in the rat lens nucleus, association of Lp82 with the lens insoluble fraction, and loss of Lp82 mRNA. Lp82 may function early in lens maturation along with m-calpain, which then is predominant in the latter stages of maturation. Proteolysis in selenite cataract is partially caused by over-activation of Lp82.

Aging↗
PubMed1998

Nuclear receptor-binding sites of coactivators glucocorticoid receptor interacting protein 1 (GRIP1) and steroid receptor coactivator 1 (SRC-1): multiple motifs with different binding specificities.

The activity of the AF-2 transcriptional activation function of nuclear receptors (NR) is mediated by the partially homologous transcriptional coactivators, glucocorticoid receptor interacting protein 1 (GRIP1)/transcriptional intermediary factor 2 (TIF2) and steroid receptor coactivator 1 (SRC-1). GRIP1 and SRC-1 bound nine different NRs and exhibited similar, but not identical, NR binding preferences. The most striking difference was seen with the androgen receptor, which bound well to GRIP1 but poorly to SRC-1. GRIP1 and SRC-1 contain three copies of the NR binding motif LXXLL (called an NR Box) in their central regions. Mutation of both NR Box II and NR Box III in GRIP1 almost completely eliminated functional and binding interactions with NRs, indicating that these two sites are crucial for most of GRIP1's NR binding activity. Interactions of GRIP1 with the estrogen receptor were more strongly affected by mutations in NR Box II, whereas interactions with the androgen receptor and glucocorticoid receptor were more strongly affected by NR Box III mutations. One isoform of SRC-1 has an additional NR Box (NR Box IV) at its extreme C terminus with an NR-binding preference somewhat different from that of the central NR-binding domain of SRC-1. GRIP1 has no NR Box in its C-terminal region and therefore no C-terminal NR-binding function. In summary, GRIP1 and SRC-1 have overlapping NR-binding preferences, but specific NRs display both coactivator and NR Box preferences that may contribute to the specificity of hormonal responses.

Amino Acid Sequence↗
PubMed1998

[Psychological and neurobehavioral effects of aluminum on exposed workers].

OBJECTIVE: To explore neurotoxicity and the changes in psychological and neurobehavioral functions in workers exposed to aluminum. METHODS: Psychological status and neurobehavioral functions of 103 exposed workers and 64 controls were examined with Neurobehavioral Core Test Battery recommended by World Health Organization (WHO), and meanwhile, air concentrations of aluminum in the workplaces and urine levels of aluminum in the exposed workers were determined. RESULTS: Urine levels of aluminum in the exposed workers were markedly higher than those in non-exposed controls, with a statistical significance. Scores for tension, depression, anger, fatigue and confusion in the workers exposed to aluminum for more than ten years were significantly more than those in non-exposed controls. Scores of the performance of Santa Ana, digit symbol and pursuit aiming in the former were significantly lower, and no other changes in psychological and behavioral functions was found in workers exposed for less than ten years, except for their scores of pursuit aiming. CONCLUSION: Obvious changes in psychological status, neuromotor speed and their accuracy were observed in workers exposed to aluminum for a long term.

Adult↗
PubMed1998

[Reduction mammaplasty using the modified inferior dermal-glandular pedicle].

OBJECTIVE AND METHODS: A modification technique for reduction mammaplasty with an inferior dermal-glandular pedicle was designed. RESULTS: The paper reports the operation results of 132 breasts in 67 patients, who received reduction mammaplasty in "Chirurgic Esthetique Europeenne," Strasbourg, France, from Jan, 1994 to Nov, 1995. CONCLUSION: Clinical applications showed aesthetic and safe results with reliable nipple areola survival and preservation of nipple sensitivity.

Adolescent↗
PubMed1998

[Relationship between health status and work ability among elderly Al exposed workers].

In this study, health status and work ability of 80 elderly male workers exposed to aluminum (Al) were assessed by physiological and neurobehaviral tests. The results showed that workers with cardiovascular or respiratory diseases had lower work ability index(WAI). Vital capacity and musculoskeletal function index(MSFI) were correlated closely with work ability. Mental performance capacity decreased with the increasing of age, and mental performance score was associated with work ability. It is suggested that vital capacity and MSFI may serve as index reflecting physical work ability of Al-exposed workers. Simple reaction time, visual memory, manual dexterity and pursuit aiming may reflect mental work ability.

Adult↗
PubMed1998

[Rapid microdose 14C-urea breath test for detection of Helicobacter pylori infection].

The purpose of this study was to develop and evaluate a rapid microdose 14C-urea breath test (14C-UBT) with a simplified protocol for detecting the infection of hilicobacter pylori (HP). 157 fasting patients who underwent endoscopy with histological examination and rapid urease test (RUT) were given a drink of 37 kBq of 14C-urea. Samples of breath carbon dioxide (1 mmol) were collected at baseline and 10, 20 and 30 min after administration by trapping in hyamine solution. 14C activity was measured by liquid scintillation counting. Results were expressed as cpm. Histolal examination and RUT were used as gold standard for the detection of HP infection. The cutoff value was selected as 200 cpm at 10 min. The results showed that the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 94.79%, 90.16%, 93.81%, 91.60% and 92.99% respectively. In this study, a 10 min, single sample, 37 kBq 14C-urea breath test for detection HP was developed. The test has good diagnostic accuracy with minimal radiation exposure and low cost. Thus, the authors considered the test to be reliable, safe, convenient and cost-effective to clinical use.

Adolescent↗
PubMed1998

[Placental morphometriological study on prolonged and delayed pregnancy and its relationship to pregnancy outcome].

OBJECTIVE: To study the morphological characteristics of the placental villous vessels and uteroplacental spiral arteries in the prolonged and delayed pregnancy and its relationship to pregnancy outcome. METHODS: Placentae from 20 cases of prolonged pregnancy (PP), 15 cases of delayed pregnancy (DP), and 29 cases of normal term pregnancy (NTP) were examined by morphometriological feature image analysis. RESULTS: Significant differences were found between PP and NTP groups (P < 0.05) in the following findings: the placental weights, the numbers of the placental villus with the syncytial knots, cytotrophoblasts, thickening of basal lamina, fibrinoid necrosis, vasculosyncytial membranes, and the diameter, perimeter and area of the villi the spiral artery wall thickening of the uteroplacental bed, and the incidences of the oligoamnios and amniotic fluid meconium staining. Significant differences of the villus perimeter and oligoamnios were only found between DP and NTP (all P < 0.05). There was no significant differences in the indices between PP and DP. As the pregnancy delayed and prolonged, the placental weights gradually decreased and the low Apgar score of neonates gradually increased. CONCLUSION: After term pregnancy the placental function is gradually lowered especially in PP. The situations of the placenta, amniotic fluid, and fetus should be frequently monitored after 40 gestational weeks.

Female↗
PubMed1998

[Uterine and placental vascular lesions in pregnancy induced hypertension and its relationship to pregnancy outcome].

OBJECTIVE: To study the vascular lesions of the uterus and placenta in severe pregnancy induced hypertension (SPIH) and its relationship to pregnancy outcomes. METHODS: 29 cases of SPIH and 29 cases of normal term pregnancies (NTP) were examined to observe the expressions of IgA, IgG, IgM and C3 in the vascular walls of placental villus and uterus placental bed by immunohistochemical technique. RESULTS: (1) In SPIH, the positive expression rates of the IgA, IgG, IgM and C3 in the vascular wall of placental villus (20.1%, 24.1%, 72.4%, and 65.5%) and uterus placental bed (20.0%, 20.0%, 70.0% and 60.0%) were significantly higher than those of NTP (all P < 0.05), while there were no expression in NTP. (2) The thickening of endangium angiostenosis, fibronoid necrosis and acute arterial atherosis were found at the sites of positive expressions in SPIH. (3) In SPIH complicated by intrauterine growth retardation (IUGR), the positive expressions of the immunocomplex and complement in the vessel walls (76.2%) were significantly higher than those of the SPIH without IUGR (50%, all P < 0.05). CONCLUSION: In SPIH, there are depositions of immunocomplex and complement on the vessel walls of placental villus and uteroplacenta. Immunological factor plays an important role in the development of PIH.

Adult↗