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Biomedical subjects

F D Xu

Publications and source records attributed to F D Xu.

7 recordsLinked to original sources
PubMed1997

Major origin of mutagenicity of chlorinated drinking water in China: humic acid or pollutants.

Since Loper and Glatz (J. Toxicol. Environ. Health, 4:919-938;1978) discovered the presence of the mutagenicity in drinking water after chlorination in 1978, humic acid (HA) has been considered as an important source. But our research results show that only 1/8 of observed direct frameshift mutagenicity in tap water originated from chlorination of HA isolated from raw water. Contamination from industrial waste and human settlement (night soil) are important potential sources of mutagenicity in chlorinated drinking water. The results show that mutagenicity from night soil after chlorination depended upon pH of sample. Production of mutagenicity at pH 6 is ten times of that at pH 8, and decomposition process is necessary condition for mutagenicity production. Season variation of mutagenicity of tap is also presented in the paper.

China↗
PubMed1996

HER-2/neu gene amplification in cervical cancer in Chinese women of Hong Kong and China.

OBJECTIVE: To determine the amplification of proto-oncogene HER-2/neu in invasive cervical cancer and its relationship with the stage of disease, grade of tumor and prognosis of patients. METHODS: In this retrospective study 70 women with invasive cervical squamous cell carcinoma were included. DNA was extracted from the paraffin-embedded tumor tissue. The amplification of HER-2/neu was studied using a differential polymerase reaction (PCR) technique. Assessment of significance was performed using Peason's Chi-square test and Fisher's exact test. RESULTS: Eleven of the 70 cases (16%) showed an amplification of HER-2/neu but there was no relation between amplification and tumor histologic grading (p = 0.408) or clinical staging (p = 0.180). Follow-up information in 67 patients was available. The incidence of amplification in the patients who were alive with disease was not statistically different from that in the patients who were alive with no evidence of disease (p = 0.315). The incidence of amplification in the patients who died of disease was higher than that in the patients who were still alive, but statistical significance did not reached (p = 0.062). CONCLUSION: The results suggest that HER-2/neu amplification does exist in a subgroup of invasive cervical cancer and may play a role in cervical carcinogenesis. The role as independent prognostic factor has to be evaluated by further prospective studies.

Base Sequence↗
PubMed1992

Augmented hypoxic ventilatory response in men at altitude.

To test the hypothesis that the hypoxic ventilatory response (HVR) of an individual is a constant unaffected by acclimatization, isocapnic 5-min step HVR, as delta VI/delta SaO2 (l.min-1.%-1, where VI is inspired ventilation and SaO2 is arterial O2 saturation), was tested in six normal males at sea level (SL), after 1-5 days at 3,810-m altitude (AL1-3), and three times over 1 wk after altitude exposure (PAL1-3). Equal medullary central ventilatory drive was sought at both altitudes by testing HVR after greater than 15 min of hyperoxia to eliminate possible ambient hypoxic ventilatory depression (HVD), choosing for isocapnia a P'CO2 (end tidal) elevated sufficiently to drive hyperoxic VI to 140 ml.kg-1.min-1. Mean P'CO2 was 45.4 +/- 1.7 Torr at SL and 33.3 +/- 1.8 Torr on AL3, compared with the respective resting control end-tidal PCO2 of 42.3 +/- 2.0 and 30.8 +/- 2.6 Torr. SL HVR of 0.91 +/- 0.38 was unchanged on AL1 (30 +/- 18 h) at 1.04 +/- 0.37 but rose (P less than 0.05) to 1.27 +/- 0.57 on AL2 (3.2 +/- 0.8 days) and 1.46 +/- 0.59 on AL3 (4.8 +/- 0.4 days) and remained high on PAL1 at 1.44 +/- 0.54 and PAL2 at 1.37 +/- 0.78 but not on PAL3 (days 4-7). HVR was independent of test SaO2 (range 60-90%). Hyperoxic HCVR (CO2 response) was increased on AL3 and PAL1. Arterial pH at congruent to 65% SaO2 was 7.378 +/- 0.019 at SL, 7.44 +/- 0.018 on AL2, and 7.412 +/- 0.023 on AL3.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1991

Anomalous hypoxic acidification of medullary ventral surface.

In castrated male goats, two flexible catheters, one open ended for reference and the other ending in a 1-mm-diam glass bulb pH electrode, were advanced ventrally through a left posterior fossa craniotomy into the subarachnoid space between the 9th and 10th cranial nerve roots, passing medially into cerebrospinal fluid (CSF) over the medullary ventral surface (MVS). They were anchored to dura and fascia, tunneled under the scalp, and terminated in connectors on the left horn. After several days for recovery, while the animals were awake, the effects of CO2 and hypoxia on pH of the film of CSF between the pia and arachnoid (pHMVS) were recorded along with end-tidal PCO2 and PO2 (mass spectrometer), ventilation (pneumotachometer) through a permanent tracheostomy, and, when possible, ear arterial O2 saturation (SaO2). High PCO2 acidified MVS as expected: delta pH MVS/delta log PCO2. = -0.64 +/- 0.14, producing a ventilatory response slope delta VI/delta pHMVS = 372 l/min. Hypoxia resulted in acid shifts even when PCO2 was allowed to fall. The development of hypoxic acidosis was related to the location of pH electrodes determined at necropsy. In isocapnic hypoxia, pH over putative chemoreceptor surfaces fell in proportion to desaturation: delta pHMVS = 0.0033(SaO2)-0.34, r = 0.80, Sy.x = 0.025. With uncontrolled arterial PCO2, similar acidosis occurred when SaO2 fell below 85-90%: delta pHMVS = 0.0039(SaO2)-0.34, r = 0.88, Sy.x = 0.032. With constant hypoxia, pH fell (tau = 3.7 +/- 2.2 min) to a plateau after 10-20 min and showed rapid recovery (tau = 2.0 +/- 1.3 min).(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1991

Studies on the mutagenicity of hair dyes made in China.

A total of 13 commercial hair dye products made in China were tested for mutagenicity in 2 short-term bioassays, the histidine-requiring mutants of Salmonella typhimurium (strains TA98 and TA100) and the micronucleus test with mouse bone-marrow polychromatic erythrocyte cells in vivo. The results showed that the 13 hair dyes were not mutagenic in strains TA98 and TA100 with and without S-9. In the micronucleus test, no mutagenic effect was observed.

Animals↗