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Biomedical subjects

Z Xu

Publications and source records attributed to Z Xu.

624 records · Page 35Linked to original sources
PubMed1982

Study of lung flukes from Philippines: --a preliminary report.

In this paper taxonomic study on paragonimus including their metacercariae obtained from the crabs collected from Sorsogon, Luzon, Philippines and adult worms and ova obtained through animal feeding, with light microscopy and scanning electron microscopy revealed that there may exist two or more species of lung flukes in Philippines. The occurrence of Semisulcospira libertina in addition to Antemelania dactylus (Lea) as an additional snail host is mentioned for the first time. The chromosome Karyotyping of the adult worms revealed that they belong to the diploid pattern. Electronic scanning showed that the cuticular spines of the Paragonimus from Sorsogon look like "pineapple ears" both in distribution and in appearance, a new finding that has not been recorded before. In the lungs of a white rat killed 290 days after infection, two adult worms were obtained within the solitary cyst. These 2 adult worms measured 4.5 x 2.5 mm and 4.5 x 3.0 mm respectively. Their unusually small size and somewhat round shape suggest that they may be of a different species from those hitherto reported in the Philippines. Clearcut evidence is presented for the first time, demonstrating the occurrence of the phenomenon of cross fertilization (allogamy) of lung flukes.

Animals↗
PubMedDate not supplied

Effect on intimal hyperplasia of dexamethasone released from coated metal stents compared with non-coated stents in canine femoral arteries.

PURPOSE: Polymer-coated, dexamethasone (DXM)-releasing stents were tested in order to assess the efficacy of DXM released locally for the prevention of stent restenosis due to intimal hyperplasia. METHODS: Strecker stents coated with a biodegradable membrane containing DXM were implanted percutaneously into the femoral artery in 14 dogs. The contralateral artery received a conventional non-coated stent serving as control. The drugs are eluted by degradation of the carrier membrane. Follow-up intraarterial digital subtraction angiography (DSA) was obtained at 3, 6, 9, 12, and 24 weeks with subsequent autopsy. Specimens for gross and microscopic pathology were obtained and histomorphometry was performed. RESULTS: Four of 14 DXM-coated stents showed thrombotic occlusion within the first 3 weeks; ten DXM-coated stents remained patent. At follow-up DSA, DXM-coated stents showed a significantly wider lumen than the non-coated stents. At morphometry there was less intimal hyperplasia over DXM-coated stents than over non-coated stents (p < 0.05). CONCLUSION: DXM-coated stents reduce neointimal hyperplasia in dogs when compared with non-coated stents.

Angiography↗
PubMedDate not supplied

A new immune escape mutant of hepatitis B virus with an Asp to Ala substitution in aa144 of the envelope major protein.

A new hepatitis B virus (HBV) mutant with an Asp to Ala substitution in aa144 of the envelope major protein was identified from the blood samples of two persistently infected patients. They were born to HBsAg-positive carrier mothers. The patients had been immunized with HBV vaccine after birth, under a standard schedule of 3 injections at 0, 1 and 6 months, but failed to be protected. The mutant was stable and was present in the blood samples collected at 1 and 4 years of age from patient 105. To study the antigenic differences, two expression plasmids, pExpW (wild type) and pExpM (mutant), were constructed, and HBsAgs were expressed in COS-M6 cells. The binding activities of the HBsAg from pExpW and pExpM were compared with anti-a-epitope monoclonal antibody and with anti-HBs polyclonal antibody, respectively, by radioimmunoassay. The results showed that the binding activity of HBsAg of pExpM was distinctly lower than that of pExpW, and the HBV mutant with envelope major protein144Asp-->Ala was shown to be a new immune escape variant.

Alanine↗
PubMedDate not supplied

Concept design of computer-aided study on traditional Chinese drugs.

Traditional Chinese drugs (TCDs) have played a key role for Chinese people in the treatment of diseases since ancient times. The use of TCDs has generated a great amount of information in the past thousand years about the relationship between natural products and the human body. However, up to now, our understanding on the mode of action of the TCD is still limited. Considering that the basic mechanism of all drug function involves the interaction between the drug and biological receptors at the molecular level, we propose to connect TCDs with modern medicine theory through molecular structures. We propose to explain functions of TCDs by using the knowledge developed in modern molecular biology, pharmacology, computer chemistry, and biochemistry. We are working on a computer-aided Chinese drug study that is discussed in this paper. A short introduction on the progress of our research is also given.

Artificial Intelligence↗
PubMedDate not supplied

Air pollution and daily mortality in Shenyang, China.

The authors analyzed daily mortality data in Shenyang, China, for calendar year 1992 to identify possible associations with ambient sulfur dioxide and total suspended particulates. Both total suspended particulate concentrations (mean = 430 microg/m3, maximum = 1,141 microg/m3) and sulfur dioxide concentrations (mean 197 = microg/m3, maximum = 659 microg/m3) far exceeded the World Health Organization's recommended criteria. An average of 45.5 persons died each day. The lagged moving averages of air-pollution levels, calculated as the mean of the nonmissing air-pollution levels of the concurrent and 3 preceding days, were used for all analyses. Locally weighted regression analysis, including temperature, humidity, day of week, and a time variable, showed a positive association between daily mortality and both total suspended particulates and sulfur dioxide. When the authors included total suspended particulates and sulfur dioxide separately in the model, both were highly significant predictors of daily mortality. The risk of all-cause mortality increased by an estimated 1.7% and 2.4% with a 100-microg/m3 concomitant increase in total suspended particulate and sulfur dioxide, respectively. When the authors analyzed mortality separately by cause of death, the association with total suspended particulates was significant for cardiovascular disease (2.1%), but not statistically significant for chronic obstructive pulmonary diseases (2.6%). In contrast, the association with sulfur dioxide was significant for chronic obstructive pulmonary diseases (7.4%), but not for cardiovascular disease (1.8%). The mortality from cancer was not associated significantly with total suspended particles or with sulfur dioxide. The correlation between sulfur dioxide and total suspended particulates was high (correlation coefficient = .66). When the authors included sulfur dioxide and total suspended particulates simultaneously in the model, the association between total suspended particulates and mortality from all causes and cardiovascular diseases remained significant. Sulfur dioxide was associated significantly with increased mortality from chronic obstructive pulmonary diseases and other causes. The results of the current study reveal increased mortality associated with both total suspended particulates and sulfur dioxide.

Air Pollution↗
PubMedDate not supplied

American ginseng improves glycemia in individuals with normal glucose tolerance: effect of dose and time escalation.

OBJECTIVE: We studied the effect of escalating the dose and administration time of American ginseng (AG, Panax quinquefolius L.) in nondiabetic individuals to achieve further improvements in glucose tolerance seen previously when 3 g of AG was taken 40 minutes before a 25 g glucose challenge. METHODS: Ten nondiabetic individuals (6M:4F; mean +/- STD: age = 41 +/- 13 years, BMI = 24.8 +/- 3.5 kg/m2, FBG = 4.5 +/- 0.1 mmol L(-1)) on 12 separate occasions, randomly received 0 (placebo), 3, 6 or 9 g of ground AG root at 40, 80, or 120 minutes before a 25 g oral glucose challenge. Capillary blood glucose was measured prior to ingestion of AG or placebo capsules and at 0, 15, 30, 45, 60 and 90 minutes from start of challenge. RESULTS: Compared with the placebo, 3, 6 and 9 g of AG reduced (p<0.05) postprandial incremental glucose at 30, 45 and 60 minutes; also, 3 and 9 g of AG did so at 90 minutes. At 60 minutes, 9 g of AG reduced incremental postprandial glucose relative to 3 g of AG (p<0.05). All AG doses reduced (p<0.05) area under the incremental glucose curve (3 g, 26.6%; 6 g, 29.3%; 9 g, 38.5%). AG taken at different times did not have an additional influence on postprandial glycemia. CONCLUSIONS: In nondiabetic individuals, 3, 6 or 9 g of AG taken 40, 80 or 120 minutes before a glucose challenge similarly improved glucose tolerance.

Adult↗
PubMedDate not supplied

CHML suppresses cell growth and induces apoptosis in multiple human tumor lines.

In the present study, we have investigated the effect of cytotropic heterogeneous molecular lipid (CHML), a new anticancer agent, on growth suppression in a variety of human tumor cell lines. At a non-toxic concentration (a range from 25 micrograms/ml to 100 micrograms/ml), CHML has shown to strongly inhibit tumor cell growth by using a typical colony survival assay. At a treatment of concentration of 50 micrograms/ml for 6 hours, CHML is able to suppress 50% of the tumor cell colony formation. At a concentration of 100 micrograms/ml (the therapeutic dosage in the clinical trial), more than 90% of the cells were killed in human breast carcinoma MCF-7, colorectal carcinoma RKO, kidney carcinoma G410, lung carcinoma and human myeloid leukemia ML-1 lines. In contrast, growth suppression of non-cancerous human skin fibroblasts by CHML was observed much less than that seen in tumor lines. These results indicate that CHML is an efficient inhibiting agent in tumor cell growth and is able to generate greater suppression in tumor cells than in noncancerous cells. With the use of DNA fragmentation assay, CHML was found to induce apoptosis in MCF-7, ML-1, H1299 and RKO lines after treatment at a concentration of 75 micrograms/ml for 8 hours. Following the CHML treatment, the tumor suppressor p53 protein elevated in RKO cells at 2 h posttreatment. The induction of p53 reached a peak at 4 hr and returned to normal level 16 hr later. Consistent with this result, Bax, which is regulated by p53 and is able to promote apoptosis, was also found to increase in a same kinetic manner as p53. These results suggest that the p53-pathway is activated by CHML and the activation of p53 may contribute to CHML-induced apoptosis in some tumor cells, such as MCF-7, RKO and ML-1. Considering that CHML is able to induce apoptosis in H1299 cells, which are of p53-negative status, it is speculated that CHML induces programmed cell death through both the p53-dependent and- independent pathways.

Antineoplastic Agents↗
PubMedDate not supplied

Calculation of dose distribution near an innovative concentric balloon catheter for endovascular brachytherapy.

PURPOSE: Using a radioactive solution-filled catheter for intravascular irradiation has the potential problem of chemical and radiological toxicity in the case of a balloon rupture. In order to reduce this risk, an innovative concentric balloon catheter was developed. METHODS AND MATERIALS: The concentric balloon was made by inner and outer balloons filled with saline and radioactive solution, respectively. The optimal inner radius was determined by comparing the dose rate reduction vs. the volume reduction for various inner and outer radii for 188Re, 32P, and 90Y solutions. RESULTS: For a balloon with an outer radius of 1.5 mm, there was no advantage of a concentric balloon. For balloons with outer radii of 3.0 and 5 mm, the optimal inner radius was 1.5 and 3 mm, respectively. CONCLUSIONS: With the newly designed concentric balloon, the risk of toxicity can be reduced while keeping the dose rate high enough so that the treatment times within tolerable limits are still maintained.

Brachytherapy↗
PubMedDate not supplied

Antitumor activity of cytotropic heterogeneous molecular lipids (CHML) on human breast cancer xenograft in nude mice.

Cytotropic heterogeneous molecular lipid (CHML), which is a new anticancer agent with US patent number 5,260,067, has recently been shown to suppress tumor cell growth in multiple tumor lines and induce apoptosis in vitro (1). These results indicate that CHML may be an effective antitumor agent. In the present study, using both local injection and intravenous injection, we have investigated the suppressive effect of CHML on human breast caner cells MCF-7 xenograft in nude mice. In the local injection, CHML was introduced into nude mice implanted with human breast cancer xenograft at doses of 25 mg/tumor area (cm2), 35 mg/tumor area (cm2), or 50 mg/tumor area (cm2), once every two days, total 3 times. The inhibition of tumor growth was 81.3%, 93.8% and 100%, respectively. In the intravenous injection, the nude mice bearing MCF-7 xenografts were treated with CHML at 10 mg/kg/day, or 15 mg/kg/day, or 20 mg/kg/day, once a day, total 7 days, the growth inhibition of tumor area was 58.1%, 77.4%, and 83.9%, respectively. At the same time, the toxicity of CHML was determined through examining the number of the white blood cell (WBC) and the activity of the serum glutamic-pyruvic transaminase (SGPT). However, no evident alterations of WBC and SGPT were detected in all animals treated with CHML, suggesting that CHML has little toxicity on nude mice. Taken together, these results indicate that CHML is an effective agent that suppresses breast tumor growth and suggest the possibility of using CHML in the clinical trial in the near future.

Alanine Transaminase↗
PubMedDate not supplied

Irradiation of singly and doubly transduced murine neuroblastoma cells expressing B7-1 and producing interferon-gamma reduces their capacity to induce systemic immunity.

We have previously reported that immunization with low major histocompatibility complex (MHC) class I expressing murine neuroblastoma (neuro-2a) transduced with B7-1 fails to induce significant protection to wild-type tumor challenge. In this study we investigated whether B7-1 expressing neuro-2a cells can stimulate an effective T-cell response if they were cotransduced with the interferon-gamma (IFN-gamma) gene to upregulate MHC class I. Transfer of both the IFN-gamma and B7-1 genes into neuro-2a (N-2a/B7-1/IFN) almost completely abrogated the tumorigenic potential of this tumor and improved survival when compared with mice receiving the single transductants, N-2a/IFN and N-2a/B7-1. Rejection of N-2a/B7-1/IFN was mediated primarily by CD8+ T cells. When irradiated tumor cells were tested, IFN-gamma gene transfer into neuro-2a significantly increased immunogenicity, but transfer of the B7-1 gene did not. However, nonirradiated N-2a/B7-1, N-2a/IFN, and N-2a/B7-1/IFN cells were significantly more effective in eliciting systemic immunity against subsequent wild-type tumor challenge than their irradiated counterparts. N-2a/B7-1/IFN was more immunogenic than N-2a/B7-1 but not more than N-2a/IFN, indicating that B7-1 does not further increase immunogenicity of neuro-2a over that induced by IFN-gamma transduction. These findings should be considered when designing gene modified tumor vaccines for use in human trials.

Animals↗