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Biomedical subjects

Q Zhang

Publications and source records attributed to Q Zhang.

At least 793 records · Page 44Linked to original sources
PubMed1995

[Simplified enzyme-linked immunoadsorbent assays for myelin basic protein and antibodies to myelin basic protein].

Synchronous quantitative determination using simplified enzyme-linked immuno adsorbent assay has been developed for myelin basic protein (MBP) and antibodies to myelin basic protein (Anti-MBP). Antisera were prepared by immunizing rabbits with purified MBP from human white matter. Antibodies to MBP was conjugated with horseradish peroxidase (HRP) by using modified periodate oxidation method. Minimum detection amounts of MBP and Anti-MBP are 0.25 ng/ml and 0.20 ng/ml respectively. The activities of Anti-MBP-HRP conjugates are stable (stored at -30 degrees C) for at least 2 years. The detection procedure can be accomplished within 24 hours.

Animals↗
PubMed1995

[Physicochemical characteristics of gentamicin polybutylcyanoacrylate nanoparticles].

Several formulations of gentamicin nanoparticle (GM-NP) colloids were prepared by the emulsion polymerization technique using the polybutylcyanoacrylate as the carrier. Various kinds of physicochemical characteristics, such as particle size and size distribution, drug loading and associating ratio, surface zeta potential, surface tension, turbidity, relative density, viscosity, refractive index and acidity were observed, determinated and compared. The results of the experiments have contributed to a full understanding of the physicochemical characteristics of gentamicin nanoparticles and also provided a basis for the establishment of the quality evaluation methods.

Drug Carriers↗
PubMed1995

Specific cleavage of two target sequences of the tobacco mosaic virus RNA by a di-component ribozyme.

Two di-component ribozymes RZ34 and RZ13, the simplest forms of multi-component ribozymes, by ligating mono-ribozymes RZ3 and RZ4 and RZ1 and RZ3 were constructed, respectively. The in vitro results indicate that each di-component ribozyme is able to cleave two different TMV transcripts, with the specificity and efficiency similar to their mono-ribozyme counterparts. Possible effects on the specificity and efficiency by temperature and the positions of the component-ribozymes in these di-component ribozymes were also studied.

Base Sequence↗
PubMed1995

[Studies on in vitro release kinetics of gentamicin sulfate polybutylcyanoacrylate nanoparticles].

The in vitro release characteristics of gentamicin sulfate polybutylcyanoacrylate nanoparticles were studied using a dialysis system comprising dialysis bag and receptor chamber. The whole apparatus was placed in a water bath shaker thermostated at 37 degrees C, and shaken at 50 cpm. The concentration of gentamicin in the receptor chamber was periodically determined by first derivative spectrometry. The results showed that the in vitro release of gentamicin sulfate from polybutylcyanoacrylate nanoparticles is characteristically biphasic, with an initial fast release (the burst effect), followed by a much slower release. These release profiles can be well modelled using a biexponential function. The related parameters of release kinetics have been calculated according to the biexponential function, and some factors that may affect the release characteristics were studied.

Drug Carriers↗
PubMed1995

Effects of TNF alone or in combination with chemotherapeutic agents on human ovarian cancers in vitro and in nude mice.

Using the tetrazolium (MTT) assay, we examined the cytotoxicities of recombinant human tumor necrosis factor (rhTNF) and five chemotherapeutic agents, namely CTX, 5-FU, VCR, DDP and KSM, on human ovarian cancer cell lines OVCAR3 and CAOV3. The results showed that the cytotoxicities of rhTNF at concentrations of 50-50,000 U/ml on OVCAR3 cell line and CAOV3 cell line exposed to rhTNF for 24 hours were from 14.2% +/- 6.8% to 67.2% +/- 3.0% and from 8.2% +/- 4.3% to 60.9% +/- 1.3%, respectively. The cytotoxicities of all five chemotherapeutic agents tested on the two cell lines were much lower than that of rhTNF. We also studied the combined antitumor potential of rhTNF with the five chemotherapeutic agents and the results showed that there were various degrees of synergism in cytotoxicities of rhTNF in combination with DDP or KSM on the two cell lines. Based on experiments in vitro, the in vivo antitumor activities of rhTNF, both alone and in combination with KSM, were examined in OVCAR3 cancer transplanted in nude mice. The results showed a considerable antitumor effect of rhTNF when it was used alone and a marked synergistic effect when it was used in combination with KSM on the xenograft tumors.

Animals↗
PubMed1995

[An in vivo study on DNA-protein crosslinks induced by nickel chloride].

DNA-protein crosslinks (DPC) in the white blood cells (WBC) and lung tissues were detected with a new and sensitive 125I-post-labelling technique in male Sprague-Dawley rats injected peritoneally (i.p.) with nickel chloride (NiCl2). Results showed DPC in the WBC and lungs of the rats increased significantly 20 hours after acute exposure to NiCl2. Multiple small doses (10 mg/kg i.p., twice a week for three weeks) of NiCl2 had similar effects as single large dose (30 mg/kg). It suggested DPC could be used as a biomarker to reflect genotoxicity to the WBC and lungs caused by nickel compound. DPC in the WBC increased more obviously than that in the lungs after exposure to NiCl2, and both correlated to each other. It showed DPC in the WBC can be used as a surrogate to indicate genotoxic lesions in target organs.

Animals↗
PubMed1995

In vitro and in vivo temperature modulation of hepatic metabolism and DNA adduction of aflatoxin B1 in rainbow trout.

Alterations in membrane lipid composition during temperature acclimation of poikilotherms is hypothesized to compensate for direct effects of temperature on membrane fluidity. Temperature also influences disposition and actions of some xenobiotics. This suggests the potential for complex interactions between temperature and metabolism of chemical carcinogens. Whole livers and hepatic microsomes from rainbow trout acclimated at 18 degrees C have more saturated fatty acids and less mono- and polyunsaturated fatty acids than those from fish acclimated at 10 degrees C. Such changes are consistent with a role for membrane lipid fluidity in temperature compensation. When 10 and 18 degrees C acclimated fish are ip injected with 0.4 mg/kg [3H]aflatoxin B1 (AFB1) at their respective acclimation temperatures, hepatic disposition of AFB1, DNA adduction, and biliary metabolites are similar. An acute shift of 18 degrees C acclimated trout to 14 degrees C reduces [3H]AFB-DNA adduct formation, while [3H]AFB1 adduction after acute shift of 10 degrees C acclimated fish to 14 degrees C is no different than in non-shifted fish. Hepatic microsomes isolated from 10 or 18 degrees C acclimated trout, incubated with 10 microM [3H]AFB1 and calf thymus DNA between 6 and 22 degrees C exhibit no differences in the "break points" of Arrhenius plots (16 degrees C in both groups). There is, however, more in vitro DNA adduction of [3H]AFB1 by microsomes from 18 degrees C acclimated fish, a difference abolished by 0.5 mM alpha-naphthoflavone (ANF). These results suggest that temperature acclimation of trout differentially modifies activities of cytochrome P-450 isozymes. When assayed at respective acclimation temperatures, hepatic cytosol from 18 degrees C fish produces more aflatoxicol, a detoxication product of AFB1, than cytosol from 10 degree C fish. Therefore, this soluble enzyme does not exhibit ideal temperature compensation. Such temperature-induced differences in microsomal cytochrome P-450 isozymes and cytosolic dehydrogenase partially explain temperature-modulated AFB1 genotoxicity.

Acclimatization↗
PubMed1995

[Inhibitive effects of spirulina on aberrant crypts in colon induced by dimethylhydrazine].

Precancerous pathological changes of colon was induced by single injection in a short-term and multiple injection in a long-term intraperitoneally with 1,2-dimethylhydrazine (DMH) in NIH mice and Sprague-Dawley rats. And, protective effects of spirulina, germanium-132 and vitamin E on colon aberrant crypts induced by DMH were observed. Results showed either single injection or multiple injection with DMH could induce aberrant crypts in colon. The number of aberrant crypts scattered by short-term single injection was less than that by multiple one, and less of the aberrant crypts foci were formed by short-term single injection. Spirulina powder, germanium-132 and vitamin E all could inhibit the function of aberrant crypts of colon. In the ninth week during multiple injection with DMH, a lot of aberrant crypts of colon had been induced, and a certain amount of aberrant crypts foci had been generated. The number of aberrant crypts and aberrant crypts foci in the animals with tumor increased with the length of DMH injection. In the ninth-, 13th- and 16th-week, respectively, the number of aberrant crypts and aberrant crypts foci was significantly less in animals protected by spirulina than in positive controls (P < 0.01), but there was no significant difference between them during 21st- and 24th-week of injections.

Animals↗
PubMed1995

%VO2max versus %HRmax regressions for six modes of exercise.

The purpose of the study was to compare the %VO2max versus %HRmax regression equations developed from data collected during incremental work on six exercise modes: treadmill (T), cycle (C), skier (S), shuffle skier (SS), stepper (ST), and rower (R). Ten active males were habituated to all modes and then performed an incremental test to maximum on each mode. Mode order was assigned by Latin square sequences and the tests were separated by at least 72 h. VO2 and HR were recorded at each increment. Regression analyses were performed using SAS-GLM. Regressions for T, S, SS, and ST were not significantly different. C had a lower intercept and higher slope, while R had a higher intercept and lower slope than the other exercise modes. These results suggest that weight bearing exercise modes have similar %VO2max-%HRmax regressions. However, weight supported and arm exercise modes appear to have different regressions.

Adult↗
PubMed1995

Community level cancer control in a Texas barrio: Part II--Base-line and preliminary outcome findings.

In a quasiexperimental demonstration study, screening rates for breast and cervical cancers were measured among Mexican-American women in selected areas of San Antonio and Houston, Tex. This research was primarily designed to evaluate a cancer-screening promotion program in San Antonio by comparing changes in screening rates in panels from the two barrio communities. In a base-line population survey, we found a small, but significant, proportion of women (10%-15%) lacking Pap smears and a larger proportion (30%-40%) lacking mammography. In a panel study following women who lacked screening at base line, there was a trend toward greater Pap smear use among younger women and a significant increase in mammography for all age groups in San Antonio compared with groups in Houston. Although there was a difference in language use between the communities, rates of newly initiated screening within the communities were similar among monolingual Spanish speakers and among those who used English, supporting the hypothesis that the program increased both groups' participation in breast-cancer screening.

Adult↗
PubMed1995

[Ultrasonic angiography in diagnosis of peripheral vascular disease].

The ability of Quickscan (QS) was studied to assess haemodynamically significant lesions in the iliac and femoro-popliteal arteries. Quickscan was prospectively and independently compared to digital subtraction angiography (DSA) of the iliac and femoro-poplited arteries. In 155 patients, 631 arterial segments were evaluated. A QS frequency ratio of greater than 1:3 had a sensitivity of 93% and a specificity of 85% in detecting stenosis > 50% diameter (75% area) reduction in the iliac artery as shown on DSA. The sensitivity and specificity for stenosis in the femoral and popliteal arteries were 85%, 96%, 82%, 98% respectively. In the detection of occlusion, QS had a sensitivity of 84% and a specifity of 98% in the iliac artery; 94%, 97%, in the femoral; and 94%, 85% in the popliteal arteries respectively. There was a significant correlation between the area reduction found by QS and the calf/brachial pressure index (CBI) (r = -0.77 P < 0.01). 35 patients underwent successfully angioplasty based on QS findings. We conclude that quickscan can provide an inexpensive, quick and noninvasive screening technique for the routine initial assessment of peripheral vascular disease.

Aged↗
PubMed1995

Expression of mu-, delta-, and kappa-opioid receptor-like immunoreactivities in rat dorsal root ganglia after carrageenan-induced inflammation.

Recently, antisera that recognize unique epitopes of the cloned mu-, delta-, and kappa-opioid, receptors (MOR, DOR, KOR, respectively) have been developed. In the present study MOR-, DOR-, and KOR-like immunoreactivities (LIs) were examined in rat dorsal root ganglia (DRGs, L4-5) after injection of carrageenan (CAR) into the hindpaw. In normal control rats 20.9%, 13.5%, and 9% of the DRG neurons contained MOR-, DOR-, KOR-LI, respectively. A marked upregulation in MOR-LI was observed in DRG neurons 1 and 3 d after inflammation. In contrast, CAR induced a distinct downregulation in DOR- and KOR-LIs. MOR-, DOR-, and KOR-LIs were preferentially localized in small DRG neurons. MOR-LI was often located in patches in the cytoplasm, and in some cells close to the somatic plasmalemma. However, DOR- and KOR-LIs mainly showed a diffuse staining pattern within cytoplasm. Two or even all three receptors could sometimes be found to coexist in DRG neurons. In the spinal cord, these receptors were mainly confined to the superficial dorsal horn, with a somewhat diffuse staining which was strong for MOR-LI, and weak for KOR-LI. DOR-LI had distinctly punctate, varicose distribution. CAG induced-alterations in opioid receptor staining in spinal cord were much less pronounced than those in the DRGs with a small increase in MOR-LI and a slight decrease in DOR-LI ipsilaterally. There was an accumulation of all three types of receptors in the sciatic nerve both proximal and distal to the ligation site as early as 2 hr, indicating both antero- and retrograde transport of multiple opioid receptors. However, DOR-LI accumulation was stronger than that of MOR- and KOR-LIs. Taken together, these results suggest that all three opioid receptors are involved in the response to inflammation and that they may play different roles in this pathological state. The coexistence of MOR, DOR, and KOR in at least some primary sensory neurons provides a substrate for functional interactions between these receptors.

Animals↗
PubMed1995

[Effect of lipid peroxide on lymphocytes and its role in postburn immunosuppression].

PURPOSE: Mechanisms of postburn immunosuppression are complicated and remain unclear. In the present experiment the effect of linoleic acid hydroperoxide (LOOH) on lymphocytes was evaluated in vitro, and then the changes in postburn lipid peroxide (LPO) levels and lymphocyte functions were measured, in order to investigate the mechanism of immunosuppression following burn. METHODS: Proliferation and IL-2 production and LPO of lymphocytes were assayed after the incubation with LOOH for in vitro study. On day 6 after induction of 11%-12% TBSA full-thickness burn, the animals were sacrificed, and proliferation and IL-2 production of splenic lymphocytes, LPO levels of the plasma, livers and spleens were measured. RESULTS: LOOH inhibited proliferation and IL-2 production and induced lipid peroxidation of lymphocytes in vitro, and Vit E could attenuate the effects of LOOH. LPO levels increased and proliferation and IL-2 production decreased after burn, but those changes in Vit E or SOD group showed no statistical significance compared with normal control group. CONCLUSION: Enhancement of lipid peroxidation and increased LPO after burn may be one of the mechanisms of postburn immunosuppression.

Animals↗