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Biomedical subjects

T Ma

Publications and source records attributed to T Ma.

At least 91 records · Page 5Linked to original sources
PubMed1998

[Color Doppler monitoring the utero-placental-fetal circulation variety of normal pregnancy and intrauterine growth retardation].

OBJECTIVE: To study the utero-placental-fetal circulation (UPFC) in normal pregnancy and intrauterine growth retardation (IUGR) cases. METHODS: Color doppler ultrasound was used to detect UPFC in 150 second and third trimester pregnant women, of which 89 cases were normal pregnancy and 58 cases were IUGR. 3 cases were IUGR with chronic renal failure. Hemodynamical value of the umbilical artery (UmA), umbilical vein (UmV) and uterine artery (UtA) were examined directly. The indices included time average velocity (TAV), pulsatility index (PI), resistance index (RI), systolic/diastolic (S/D) ratio, blood flow volume (Q). The maternal serum estriol (E3), human placental lactogen (HPL) and plasma thromboxane B2 (TXB2)/6-keto-PGF1 alpha (6-KP) were measured simultaneously. RESULTS: The result shows that in normal pregnancy group UPFC is abundant gradually with increasing gestational age. In IUGR group 92.53% of cases showed that TAV and Q of UmA, UmV markedly decreased and PI, RI and S/D ratio of UmA elevated at 20 weeks of gestation. There were significant difference between the two groups, maternal serum E3, HPL level in IUGR group were significantly lower than that of the normal pregnancy group, 6-KP level reduced, and TXB2/6-KP ratio significantly increased. CONCLUSION: Using color doppler ultrasound examining hemodynamical changes of UmA, UmV and UtA could observe UPFC function directly. It is one of the best method to early diagnose and predict the prognosis of IUGR.

Adult↗
PubMed1998

[The risk of lung cancer and mesothelioma in farmers exposed to crocidolite in environment].

To assess the risk of lung cancer and mesothelioma after environmental exposure to crocidolite for 20-30 years, a retrospective cohort study was carried out in farmers who had been exposed to crocidolite in environment. 1610 subjects were followed up for 9 years (Jan. 1, 1987 Dec. 31, 1995). The control group consisted of 7646 farmers who resided in the noncrocidolite pollution rural area in the same province. The results showed that the annual mortality rate was 43.75 per 100,000 population for lung cancer, and 36.46 per 100,000 for mesothelioma. Significantly high risks of lung cancer (RR 5.67) and mesothelioma (RR 182.3) were noted. These results demonstrate a strong causal association between lung cancer, mesothelioma and exposure to crocidolite.

Adult↗
PubMed1998

[Effects of different expression levels of fibronectin on biological behavior of tumor cells].

OBJECTIVE: To study the effects of fibronectin(FN) on tumor cell proliferation, adherence and invasion. METHODS: FN cDNA was introduced into a transitional carcinoma cell line 253J which expressed low level of FN, and 253 FN line which expressed higher level of FN was established. The changes of cellular proliferation in vitro were observed. Adhesiveness to the extracellular matrix was detected by MTT method. Hemotypic adhesion was investigated by detachment assay and invasiveness of the cells was observed with Boyden Chamber before and after FN cDNA gene transfection. RESULTS: The growth rate of 253-FN was decreased as compared with its parental cell 253J. Hemotypic adhesion was significantly increased. The adhesiveness of the cells to extracellular matrix was enhanced. Invasion assay showed that invasioness of 253-FN was decreased. CONCLUSION: This study suggested a correlation between FN expression and its biological behavior. With increased FN level, malignant phenotype was changed and invasive ability was inhibited.

Carcinoma, Transitional Cell↗
PubMed1998

[Determination of formic acid in urine by high performance capillary zone electrophoresis].

The amounts of formic acid in human urine has a direct bearing on the people's health. In this paper, high performance capillary zone electrophoresis was applied to separate formic acid of urine with a buffer system of 5 mmol/L phthalate-0.5 mmol/L hexadecyltrimethyl ammonium bromide (CTAB) and pH 6. Separations were performed in a 50 cm x 50 microns i.d. fused silica capillary (effective length 48.5 cm) at 25 degrees C. A negative potential of 30 kV was used for each experiment. Sample was introduced into the capillary by pressure at kPa for 10 s. Indirect UV detection was operated at 210 nm and reference wavelength at 380 nm for all experiments. Capillary was rinsed for 5 min with 0.1 mol/L sodium hydroxide and buffer solution before each run. Urine was injected directly after filtered through 0.45 micron membrane. The results are satisfactory.

Alcoholic Intoxication↗
PubMed1998

[Study on relativity between oxygen free radical and thromboxane B2, 6-keto-PGF1 alpha during ligustrazine treatment of intrauterine growth retardation].

OBJECTIVE: To study the pathophysiological changes and effective treatment of intrauterine growth retardation (IUGR). METHODS: Eighty-five cases with normal pregnancy and 58 IUGR women maternal red blood cell superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), serum lipid peroxide (LPO) and thromboxane B2 (TXB2), 6-keto-PGF1 alpha(6KP) were examined. IUGR group was divided into Ligustrazine group (LIG, 47 cases) and amino acid group (AAG, 11 cases) and treated accordingly. RESULTS: In IUGR group, LPO increased and SOD, GSH-Px activity, 6KP value decreased abnormally, TXB2/6KP ratio significantly increased, which was negative correlated with SOD, GSH-Px activity and positive correlated with LPO level markedly. After treatment, all the changes were improved and almost reached normal range. The fetal outcome showed that the total effective rate was 95.7% in LIG, markedly higher than that in AAG (81.8%, P < 0.05), there was significant difference between LIG and AAG. CONCLUSIONS: The balance of body oxidate/antioxidate system was disturbed and the uteroplacental-fetal circulation was obstracted in IUGR. Ligustrazine could inhibit oxygen free radical, rise SOD, GSH-Px activity, regulate TXA2/PGI2 balance, promote fetal growth.

6-Ketoprostaglandin F1 alpha↗
PubMed1998

[Retrocaval ureter].

OBJECTIVE: To improve the diagnosis of retrocaval ureter. METHOD: 20 cases of retrocaval ureter with an average age of 33.4 years were reported. The diagnosis of this disease depends on urography and retrograde ureterography. Operation was the principal treatment. Ureter orthopedics and reduction were performed in 19 cases of type 1 (low loop) except one case of type II (high loop). After removing 3 - 4 cm retrocaval ureter with pathological changes, we anastomosed the ureter without tension and regained its normal anatomic position. RESULT: B-ultrasound and excretory urography showed no stenosis and improvement of hydronephrosis. CONCLUSION: Ureter orthopedics and reduction are ideal for the treatment of retrocaval ureter.

Adolescent↗
PubMed1998

Developmental lead exposure alters the distribution of protein kinase C activity in the rat hippocampus.

Chronic low-level lead (Pb) exposure in children is known to cause a deficit in learning and memory. In vitro studies have demonstrated that Pb altered protein kinase C (PKC) activity. Especially, hippocampal PKC has been correlated with performance in several learning tasks. The effects of Pb exposure on hippocampal PKC were investigated during development at various postnatal ages: postnatal day (PN) 7, 14, 28, and 56. Two-tenth % Pb acetate was administered to pregnant and lactating dams and then administered to weanling rats in drinking water. PKC activity was measured in both membrane and cytosolic fractions from the hippocampi of the controls and Pb-exposed animals. Pb-induced increase in PKC activity in the cytosolic fraction was observed in the PN56 rats. In contrast, PKC activity was decreased by Pb at PN7 in the membrane fraction. Furthermore, a significant decrease in the ratio of membrane to cytosolic PKC activity which is representative of PKC distribution was observed in the PN28 and PN56 Pb-exposed rats relative to the same-age controls. This study indicates that chronic Pb exposure during development influences hippocampal PKC activity and distribution. These changes may be involved in the subclinical neurotoxicity of chronic Pb exposure in young children.

Animals↗
PubMed1997

Cloning of a novel water and urea-permeable aquaporin from mouse expressed strongly in colon, placenta, liver, and heart.

An aquaporin-type water channel was isolated from mouse based on homology to known aquaporins. A 1447 bp cDNA was sequenced (designated AQP8) with a 783 bp open reading frame encoding a 261 amino acid hydrophobic protein which contained the conserved NPA motifs of MIP family members. Amino acid alignment showed greatest homology of AQP8 to plant water channel gamma TIP (38% identity) followed by mammalian water channels AQP4 (32%) and AQP2 (31%). Northern blot analysis indicated a 1.7 kb transcript expressed strongly in placenta > colon > liver approximately heart. RT-PCR with AQP8-specific primers and Southern blot analysis showed AQP8 transcript in the above tissues and in pancreas, lung, kidney, submandibular gland, diaphragm, testis, spleen, stomach and brain. Expression of AQP8 cRNA in Xenopus oocytes increased osmotic water permeability from (0.8 +/- 0.1) x 10(-3) cm/s to (22 +/- 3) x 10(-3) cm/s (10 degrees C) in a mercurial-sensitive manner. AQP8 was also permeable to urea but not to glycerol. Normalization for oocyte plasma membrane expression using cMyc-tagged AQP8 indicated a single channel water permeability of 8.2 x 10(-14) cm3/s. AQP8 is unique among the water channels in terms of its urea permeability and its strong expression in gastrointestinal organs, placenta and heart.

Amino Acid Sequence↗
PubMed1997

Effect on infant mortality of iodination of irrigation water in a severely iodine-deficient area of China.

BACKGROUND: Hotien county in Xinjiang province, China, is an area of severe iodine deficiency and has a high infantmortality rate. We investigated whether iodine replacement through iodination of the irrigation water would decrease infant mortality. METHODS: We added potassium iodate to irrigation water over a 2 to 4 week period beginning in 1992 in certain areas of three townships (Tusala, Long Ru, and Bakechi). Logistic regression analysis was used to compare the odds ratios for infant and neonatal mortality in treated and intreated areas. FINDINGS: The median urinary iodine concentration significantly increased in women of child-bearing age from < 10 micrograms/L to 55 micrograms/L. Infant-mortality rates decreased in the treated areas of Long Ru (mean [SD] 58.2 [4.4] per 1000 births to 28.7 [7.1] per 1000 births), Tusala (47.4 [12.4] per 1000 births to 19.1 [1.5] per 1000 births), and Bakechi (106.2 [9.5] per 1000 births to 57.3 [7.3] per 1000 births). Similar results were also seen for neonatal mortality. On regression analysis iodine treatment and time were significant independent predictors of infant mortality. INTERPRETATION: Iodine supplementation of irrigation water in areas of severe iodine deficiency decreases neonatal and infant mortality. Iodine replacement has probably been an important factor in the national decrease in infant mortality in China.

Adult↗
PubMed1997

Generation and phenotype of a transgenic knockout mouse lacking the mercurial-insensitive water channel aquaporin-4.

Aquaporin-4 (AQP4) is a mercurial-insensitive, water-selective channel that is expressed in astroglia and basolateral plasma membranes of epithelia in the kidney collecting duct, airways, stomach, and colon. A targeting vector for homologous recombination was constructed using a 7-kb SacI AQP4 genomic fragment in which part of the exon 1 coding sequence was deleted. Analysis of 164 live births from AQP4[+/-] matings showed 41 [+/+], 83 [+/-], and 40 [-/-] genotypes. The [-/-] mice expressed small amounts of a truncated AQP4 transcript and lacked detectable AQP4 protein by immunoblot analysis and immunocytochemistry. Water permeability in an AQP4-enriched brain vesicle fraction in [+/+] mice was high and mercurial insensitive, and was decreased by 14-fold in [-/-] mice. AQP4 deletion did not affect growth or tissue morphology at the light microscopic level. Northern blot analysis showed that tissue-specific expression of AQPs 1, 2, 3, and 5 was not affected by AQP4 deletion. Maximum urine osmolality after a 36-h water deprivation was (in mosM, n = 15) [+/+] 3,342+/-209, [+/-] 3, 225+/-167, and [-/-] 2,616+/-229 (P < 0.025), whereas urine osmolalities before water deprivation did not differ among the genotypes. Rotorod analysis of 35- 38-d-old mice revealed no differences in neuromuscular function (performance time in s, n = 8): [+/+] 297+/-25, [+/-] 322+/-28, [-/-] 288+/-37. These results indicate that AQP4 deletion in CD1 mice has little or no effect on development, survival, growth, and neuromuscular function, but produces a small defect in urinary concentrating ability consistent with its expression in the medullary collecting duct.

Animals↗
PubMed1997

Synthesis of L-ribofuranosyl C-nucleosides.

C-Nucleosides, 4-amino-8-(beta-L-ribofuranosyl)pyrazolo[1, 5-a]-1,3,5-triazine (12) and 4-amino-7-(beta-L-ribofuranosyl)-5H-pyrrolo[3,2-d]pyrimidine (L-9-deazaadenosine, 22), were synthesized from the key intermediate, 3-dimethylamino-2-(2,3-O-isopropylidene-5-O-trityl-L-ribofuranosyl) acrylonitrile (8), which was prepared from L-xylose in 11 steps.

Anti-HIV Agents↗
PubMed1997

Synthesis and anti-hepatitis B virus activity of 9-(2-deoxy-2-fluoro-beta-L-arabinofuranosyl) purine nucleosides.

Since the discovery of 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU) as a potent anti-HBV and anti-EBV agent, we have studied the structure-activity relationships of 2'-deoxy-2'-fluoro-beta-L-arabinofuranosylpyrimidine nucleosides as anti-HBV agents. Therefore it is rational to extend this study to the purine nucleosides. Thus, 3,5-di-O-benzoyl-2-deoxy-2-fluoro-beta-L-arabinofuranosyl bromide (1), which was prepared from L-xylose via a multistep procedure, was coupled with several purines by the sodium salt method. From this general synthesis, 10 purine nucleosides containing the 2-deoxy-2-fluoro-beta-L-arabinofuranosyl moiety have been obtained. The anti-HBV activity and toxicity of the synthesized nucleosides were evaluated in HepG2 2.2.15 cells. Among them, the adenine (10) and hypoxanthine (15) derivatives exhibit good in vitro anti-HBV activity (EC50 = 1.5 and 8 microM, respectively) without significant toxicity up to 200 microM.

Antiviral Agents↗
PubMed1997

Closely spaced tandem arrangement of AQP2, AQP5, and AQP6 genes in a 27-kilobase segment at chromosome locus 12q13.

The aquaporins (AQPs) are a family of water-transporting proteins that facilitate osmotically driven water movement across cell plasma membranes. Among the seven human aquaporins cloned to date (AQPs 0-6), genes encoding the four most closely related aquaporins (AQP0, AQP2, AQP5, and AQP6) have been mapped to chromosome band 12q13, suggesting an aquaporin family gene cluster at this locus. To construct a physical map and identify novel aquaporin gene members on this cluster, a human CEPH B yeast artificial chromosome (YAC) library was screened by PCR using primers derived from exon 4 of AQP2 and AQP0 genes. A YAC clone with 200 kb of human DNA was isolated and analyzed. Primary pulsed-field gel electrophoresis and Southern blot analysis indicated the presence of AQP2, AQP5, and AQP6 genes, but not AQP0. Restriction mapping and PCR analysis yielded a precise physical map in which the three aquaporin genes span only approximately 27 kb in the order, transcriptional orientation, and spacer length 5'-AQP2-5 kb spacer-AQP5-7 kb spacer-AQP6-3'.

Aquaporin 5↗
PubMed1997

Effects of subacute lead exposure on [3H]MK-801 binding in hippocampus and cerebral cortex in the adult rat.

We used the NMDA receptor non-competitive antagonist, [3H]MK-801, as a ligand for an autoradiographic study to determine the effects of lead on NMDA receptor in the rat brain. Adult male rats were administered lead acetate, 100 mg/kg, or sodium acetate, 36 mg/kg (control), by i.p. for 7 days. High lead levels were detected in blood (41.1 microg/dl) and in brain (16.7-29.4 microg/g). Concentrations of lead in brain regions were not significantly different. The [3H]MK-801 binding was heterogeneously distributed throughout the rat brain with the following order of binding densities: hippocampal formation > cortex > caudate-putamen > thalamus > brainstem. Lead exposure produced a significant decrease in [3H]MK-801 binding to the NMDA receptor in the hippocampal formation including CA2 stratum radiatum, CA3 stratum radiatum, hilus dentate gyrus and presubiculum, and in the cerebral cortex including agranular insular, cingulate, entorhinal, orbital, parietal and perirhinal areas. The hippocampal formation is known as a critical neural structure for learning and memory processes, whereas, cortical and subcortical regions have been demonstrated to be involved in the modulation of complex behavioral processes. The NMDA receptor has been demonstrated to play a key role in synaptic plasticity underlying learning and memory. Lead-induced alterations of NMDA receptors in the hippocampal formation and cortical areas may play a role in lead-induced neurotoxicity.

Animals↗
PubMed1997

Effects of chronic lead exposure on [3H]MK-801 binding in the brain of rat.

We have used quantitative autoradiographic methods to determine the effects of chronic lead exposure on N-methyl-D-aspartate (NMDA) receptors in the brain of female rat. Rats were exposed pre- and post-natally from day 4 +/- 1 post conception with 1000 ppm lead in their drinking water. This treatment continued after weaning. No effects of lead on [3H]MK-801 binding were found at PN 28. However, lead caused a significant increase in [3H]MK-801 binding in the hippocampus including CA1 and CA2, and in the occipital and temporal cortical areas at PN 56 and at PN 112. An increase in binding was also found in the entorhinal cortex and the dentate gyrus at PN 112. Because the NMDA receptor is involved in learning and memory, the lead-induced disruption of NMDA receptors in the hippocampus and cortex may be associated with the cation-induced cognition deficits.

Animals↗
PubMed1997

Increased release of excitatory amino acids in rat locus coeruleus in kappa-opioid agonist dependent rats precipitated by nor-binaltorphimine.

Extracellular fluid levels of glutamate and aspartate in the locus coeruleus (LC) during nor-binaltorphimine (nor-BNI)-precipitated withdrawal from butorphanol, (5alpha,7alpha,8beta)-(+)-N-methyl-N-[7-(1-pyrrolidiny l)-1-oxaspiro [4,5] dec-8-yl]-benzeneacetamide (U-69,593), or morphine were measured in rats. When the microdialysis probe was located in the core of the LC, increases in glutamate and aspartate were noted after nor-BNI (48 nmol/50 microl, LC)-precipitated withdrawal in rats that had been intracerebroventricularly infused with butorphanol (26 nmol/1 microl/h) or U-69,593 (26 nmol/10 microl/h) for 3 days. The glutamate and aspartate levels in the LC markedly increased in the butorphanol- or U-69,593-dependent rats within 60 min following administration of nor-BNI. However, there was no significant increase in levels of glutamate, and only a slight increase in levels of aspartate, after nor-BNI treatment of the morphine (26 nmol/1 microl/h)-infused rats. Behavioral signs of withdrawal (teeth-chattering, wet-dog shakes, etc.) were observed following nor-BNI challenge in the butorphanol- or U-69,593-infused rats, with only minimal signs in the morphine-infused rats, and none in the saline-infused controls. These results directly suggest that kappa-opioid receptors and excitatory amino acids within the LC mediate withdrawal in animals dependent on butorphanol or U-69,593, but not on morphine.

Animals↗