Biomedical subjects

S Bao

Publications and source records attributed to S Bao.

At least 91 records · Page 5Linked to original sources

PubMed1997

Induction of micronuclei in respiratory tract following radon inhalation.

Male Wistar rats were exposed to radon and its progeny (0.0, 60, 262 and 564 working level months, WLM), and the frequency of micronuclei was determined in deep lung fibroblasts, and deep lung, trachea and nasal epithelial cells with slopes of 0.28, 0.67, 0.34 and 0.11 micronuclei/1000 binucleated cells/WLM respectively. Micronuclei in deep lung fibroblasts, isolated and cultured using two methods and media, demonstrated no differences in slopes. Biological damage was used as a biodosimeter to calculate the relationship between dosimetric units: alpha particle traversals or 'nuclear hits', dose in mGy and exposure in WLM. The estimated number of nuclear alpha traversals/Gy was 6.3. Radon exposure to 170 WLM resulted in the same frequency of micronuclei in deep lung epithelial cells as produced by one alpha hit/cell nucleus. Absorbed dose/unit of exposure (mGy/WLM) was estimated assuming the damage was related to absorbed dose or to changes in cell sensitivity and ranged from 1.13 to 1.34 for deep lung epithelial cells, 0.47 to 1.09 for deep lung fibroblasts, 0.34 to 0.67 for tracheal epithelial cells and 0.18 to 0.33 for nasal epithelial cells. Biological dosimetry can be used to relate exposure to damage, compare dosimetric units and validate physical dosimetry models. This approach can be applied to any inhaled material capable of producing biological damage.

Animals↗

PubMed1997

Expression of luteinizing hormone/human chorionic gonadotropin receptor gene in benign prostatic hyperplasia and in prostate carcinoma in humans.

The findings that normal rat prostates express functional LH/hCG receptors led us to test the hypothesis that benign prostatic hyperplasia (BPH) and prostate carcinomas may also express this receptor gene. The data revealed the presence of LH/hCG receptor transcripts and receptor protein in normal and hyperplastic but not in atrophic glands present in BPH tissue. Smooth muscle and blood vessels in stroma of BPH tissue also contained receptors. Prostate carcinomas contain lower and more heterogeneous receptor levels than BPH tissue. Two human prostate cancer cell lines (LNCaP and DU 145) that were investigated showed the presence of a major 4.5-kilobase transcript and several minor transcripts and also the protein of LH/hCG receptors. However, androgen-sensitive LNCaP cells contained more receptors than androgen-insensitive DU 145 cells. In summary, we demonstrate for the first time that BPH and prostate cancer tissues and cell lines express LH/hCG receptor gene. These findings suggest that higher LH levels in aged men may play a role in BPH and/or prostate carcinomas.

Aged↗

PubMed1997

Presence of functional luteinizing hormone/chorionic gonadotropin (hCG) receptors in human breast cell lines: implications supporting the premise that hCG protects women against breast cancer.

We investigated MCF-7 and MDA-MB-231 human breast cancer cell lines and immortalized mammary epithelial HBL-100 cells for the presence of functional LH/hCG receptors. The results revealed that all three breast cell lines contain LH/hCG receptor mRNA transcripts and receptor proteins that can bind 125I-hCG. The MCF-7 cells, however, contain higher levels than the others. Culturing MCF-7 cells with highly purified hCG resulted in a dose- and time-dependent significant decrease in steady-state estradiol receptor mRNA and protein levels as compared to controls, with the maximal decrease occurring after 4 h of culture with 10 ng/ml hCG. The studies on cell growth demonstrated that hCG treatment in the presence of minimal or no fetal bovine serum had a time-dependent significant inhibitory effect on MCF-7 and HBL-100, but not on MDA-MB-231 cells. In summary, our results demonstrate that human breast cell lines contain functional LH/hCG receptors. The hCG effects in MCF-7 cells are consistent with a premise that hCG protects women against breast cancer.

Blotting, Northern↗

PubMed1997

Benefits of angular expression to reconstruction algorithms for collimators with spatially varying focal lengths.

Fan-beam collimators with spatially varying focal lengths are used in single photon emission computed tomography (SPECT) to improve the imaging sensitivity and to reduce the reconstruction artifacts resulting from the truncation of projection data. An angular representation of the detector coordinates for the projection data is adopted to investigate several aspects of the reconstruction problem for this type of collimation. A rebinning reconstruction algorithm is derived. We prove a conjecture posed by Zeng and Gullberg and obtain a simplified form of their backprojection filtering algorithm. Some computer simulations are presented to investigate the performance of the rebinning algorithm.

Algorithms↗

PubMed1997

[Studies on arachidonic acid production by Mortierella].

The effects of the incubation temperature, initial pH of the medium, carbon source and nitrogen source on the production of arachidonic acid by Mortierella sp. M10 were studied. Thought orthogonal experiments, the optimum culture medium was obtained (g/L): glucose, 100; yeast extract, 10; KNO3, 4.0; KH2PO4, 2.0; CaCl2.2H2O, 0.1; MgSO4.7H2O, 0.5; FeCl3.6H2O, 0.015; ZnSO4.7H2O, 0.0075; CuSO4.5H2O, 0.0005. Under the optimum culture conditions, the dry cell weight and arachidonic acid was 33.51 g/L and 0.827 g/L, respectively. The flask culture process was analysed.

Arachidonic Acid↗

PubMed1997

[Determination of trace iron and cobalt in natoral water by ammonium thiocyanate resin phase-spectrophotometry].

At the presence of Tween-80 in acid medium, Fe(III) Co(III) and SCN- are changed into coloured complexations and quantitatively absorbed on the resin. The apparent molar absorptivities of resin phase are epsilon Fe = 2.4 x 10(5)L x mol(-1) x cm(-1) at 490nm and epsilon Co = 2.1 x 10(5)L x mol(-1) x cm(-1) at 630nm by spectrophotometry. Beer's law is obeyed by Fe(III) and Co (III) in the range of 0-8microg/25mL and 0-15microg/25mL. method has been applied to natural water. Relative standard deviations are 1.7% and 5.5%, respectively.

English Abstract↗

PubMed1997

Comparative clastogenic sensitivity of respiratory tract cells to gamma rays.

To understand the relationships between exposure and damage to different cell populations in the respiratory tract, methods were developed to culture deep-lung fibroblasts and epithelial cells from the nose, trachea and deep lungs. Female F-344 Fischer and male Wistar rats were exposed to 1-5 Gy of 60Co gamma rays at a dose rate of 0.4 Gy/min. Cells were isolated for short-term culture, and the incidences of binucleated cells and micronuclei were determined. The incidences of micronuclei were determined in cytochalasin-B-induced binucleated cells at 72 h for nasal and tracheal tissue and 96 h for deep-lung fibroblasts and epithelial cells. Maximum frequencies of binucleated cells were found in the control nonirradiated cells at these harvest times, and the frequencies were not significantly affected at these harvest times by radiation exposure. No significant differences were found in the frequencies of micronuclei induced in the nasal epithelial cells isolated from female F-344 Fischer or male Wistar rats. Fibroblasts cultured in different media and isolated from either female F-344 Fischer or male Wistar rats also showed a similar frequency of micronuclei. Over the doses tested, the frequency of micronuclei in the respiratory tract cells increased linearly with the dose. The slopes were 92.2 +/- 9.2, 76.2 +/- 7.9, 32.8 +/- 2.4 and 28.7 +/- 3.4 micronuclei/1000 binucleated cells/Gy for deep-lung epithelial cells, deep-lung fibroblasts, tracheal epithelial cells and nasal epithelial cells, respectively. Deep-lung epithelial or fibroblast cells were about two to three times as sensitive for elastogenic damage as nasal and tracheal epithelial cells. The measurement of micronuclei in isolated respiratory tract cells is very useful in assessing cytogenetic damage induced in different cell types by radiation.

Animals↗

PubMed1996

Impaired classical eyeblink conditioning in cerebellar-lesioned and Purkinje cell degeneration (pcd) mutant mice.

Converging lines of evidence from rabbits, rats, and humans argue for the crucial involvement of the cerebellum in classical conditioning of the eyeblink/nictitating membrane response in mammals. For example, selective lesions (permanent or reversible) of the cerebellum block both acquisition and retention of eyeblink conditioning. Correspondingly, electrophysiological and brain-imaging studies indicate learning-related plasticity in the cerebellum. The involvement of the cerebellum in eyeblink conditioning is also supported by stimulation studies showing that direct stimulation of the two major afferents to the cerebellum (the mossy fibers emanating from the pontine nucleus and climbing fibers originating from the inferior olive) can substitute for the peripheral conditioned stimulus (CS) and unconditioned stimulus (US), respectively, to yield normal behavioral learning. In the present study, we examined the relative contribution of the cerebellar cortex versus deep nuclei (specifically the interpositus nucleus) in eyeblink learning by using mutant mice deficient of Purkinje cells, the exclusive output neurons of the cerebellar cortex. We report that Purkinje cell degeneration (pcd) mice exhibit a profound impairment in the acquisition of delay eyeblink conditioning in comparison with their wild-type littermates. Nevertheless, the pcd animals did acquire a subnormal level of conditioned eyeblink responses. In contrast, wild-type mice with lesions of the interpositus nucleus were completely unable to learn the conditioned eyeblink response. These results suggest that both cerebellar cortex and deep nuclei are important for normal eyeblink conditioning.

Animals↗

PubMed1996

Interleukin-5 mRNA expressed by eosinophils and gamma/delta T cells in parasite-immune sheep.

Interleukin (IL)-5 is produced by variety of cell types and contributes to both lymphocyte development an eosinophil terminal differentiation in vitro. The coincidence of worm expulsion and eosinophilia in sheep infected with the gastrointestinal nematode Trichostrongylus colubriformis suggest that eosinophils may be involved as effector cells in host immunity against parasite infection. The role of IL-5 in this process was investigated by observing the distribution of IL-5 mRNA+ cells in the small intestine, mesenteric lymph nodes (MLN) and Peyer's patches (PP) by an in situ hybridization technique using a murine IL-5 riboprobe. IL-5 mRNA+ cells were distributed throughout the lamina propria (LP) of the small intestine from the tips of the villi to the muscularis mucosae and in the parafollicular areas of MLN and PP in both naive and immune sheep. The phenotypes of IL-5 mRNA+ cells was explored by simultaneous eosin and immunohistochemical staining using a monoclonal antibody recognizing the T19 marker, which identifies a major subset of gamma/delta TCR+ cells in sheep. In immune sheep, there was about a five-fold increase in the number of eosinophils and IL-5 cell mRNA+ cells in the LP, but there was no significant change in numbers of T19+ cells. Most of the IL-5 mRNA cells in the LP were eosinophils, but many of the T19+ cells also expressed IL-5 mRNA. In contrast, there were fewer eosinophils than T19+ cells in MLN of immune sheep and, compared to controls, a three-fold increase in T19+ cells and a five-fold increase in T19+/IL-5 mRNA+ double positive cells observed in immune sheep. In PP, there were very few eosinophils but substantial numbers of T19+ cells; however, no significant differences in numbers of eosinophils, T19+ or IL-5 mRNA+ cells were observed between control and immune sheep. These results indicate that in sheep, both eosinophils and gamma/delta T cells are capable of IL-5 expression and suggest that IL-5 is an important regulatory factor in autocrine and paracrine activation of effector cells involved in parasite immune expulsion.

Animals↗

PubMed1996

Differential expression of interleukin-5 mRNA+ cells and eosinophils in Nippostrongylus brasiliensis infection in resistant and susceptible strains of mice.

Interleukin (IL)-5 is produced by both T cells and eosinophils and has been implicated in lymphocyte and eosinophil differentiation and maturation. The extent to which differences in IL-5 expression contribute to genetic variability in parasite immunity was investigated by comparing eosinophilia, IgE production, mastocytosis and IL-5 mRNA+ cells following Nippostrongylus brasiliensis infection of resistant (BALB/c) and susceptible (C57BL/6) mice. In uninfected mice, IL-5 mRNA+ cells detected by in situ hybridization were distributed throughout the lamina propria and crypt regions of the small intestine in both strains, but were 1.5-fold higher in BALB/c than in C57BL/6 mice. Following N. brasiliensis infection, the numbers of IL-5 mRNA+ cells in BALB/c mice continued to increase until day 11 post-infection at which time they were more than 4-fold more numerous than in uninfected control mice of the same strain. In C57BL/6 mice, IL-5 mRNA+ cells reached peak numbers on day 7 post-infection, only 1.5-fold higher than uninfected controls, but the numbers began to decline thereafter. At all time points after day 5, the numbers of IL-5 mRNA+ cells in the gut of C57BL/6 mice were significantly lower than BALB/c mice. The differences in numbers of IL-5 mRNA+ cells induced by infection in each strain of mice correlated with changes in blood and intestinal eosinophilia, mastocytosis and IgE production and was reflected in differences in worm expulsion and egg counts. Although numbers of intestinal IgA-containing cells increased in both strains after infection, there was no difference between strains except at day 11 when there were significantly higher numbers in BALB/c mice than in C57BL/6 mice. These results suggest that IL-5 is an important regulatory factor determining host immunity to parasite infection and that differential regulation of IL-5 expression explains in part the observed strain differences with respect to parasite resistance.

Animals↗

PubMed1996

Ergonomic effects of a management-based rationalization in assembly work - a case study.

Due to unsatisfactory productivity, a large company in the Swedish manufacturing industry decided to rationalize their assembly system. The intended rationalization comprised several changes with deliberate ergonomic implications. The main aim of the present study was to evaluate the impact of the rationalization on the physical work load of the operators. The work load was assessed before and after the changes using expert observations, company records and direct technical measurements. The results indicate that the intervention led to only minor changes in muscle load, body postures and movement patterns. Several of the planned initiatives were never implemented, e.g. teaching the workers multiple skills and designing work stations at which a major part of the assembly sequence could be performed. This was mainly due to a policy revision caused by changes in the market situation. In spite of the company's original intentions, the revised production system contained only minor ergonomic improvements. Thus, the realization of the ergonomic potential in a rationalization seems to depend on management culture, as well as factors outside the company.

Journal Article↗

PubMed1996

Regulation of mucosal IgA responses in vivo: cytokines and adjuvants.

The predominance of IgA plasma cells at mucosal sites reflects a combination of the selective localisation and vigorous proliferation after extravasation of IgA plasma cell precursors. Experiments are described here which demonstrate that post-extravasation events leading to IgA precursor cell retention, proliferation and antibody secretion are under cytokine control. This has led to investigation of therapeutic interventions to modify cytokine availability to maximise mucosal vaccination responses and correct IgA deficiencies.

Adjuvants, Immunologic↗

PubMed1996

Deficient cerebellar long-term depression, impaired eyeblink conditioning, and normal motor coordination in GFAP mutant mice.

Mice devoid of glial fibrillary acidic protein (GFAP), an intermediate filament protein specifically expressed in astrocytes, develop normally and do not show any detectable abnormalities in the anatomy of the brain. In the cerebellum, excitatory synaptic transmission from parallel fibers (PFs) or climbing fibers (CFs) to Purkinje cells is unaltered, and these synapses display normal short-term synaptic plasticity to paired stimuli in GFAP mutant mice. In contrast, long-term depression (LTD) at PF-Purkinje cell synapses is clearly deficient. Furthermore, GFAP mutant mice exhibited a significant impairment of eyeblink conditioning without any detectable deficits in motor coordination tasks. These results suggest that GFAP is required for communications between Bergmann glia and Purkinje cells during LTD induction and maintenance. The data support the notion that cerebellar LTD is a cellular mechanism closely associated with eyeblink conditioning, but is not essential for motor coordination tasks tested.

Animals↗

PubMed1996

Preclinical evaluation of SPECT imaging with 131I-labeled monoclonal antibody SZ39 in nude mice bearing human glioma xenografts.

The imaging characteristics of monoclonal antibody SZ39 against glioma were evaluated in glioma-bearing nude mice. Monoclonal antibody SZ39 is a murine IgG2a that reacts with a glycoprotein epitope (molecular weight 180,000), a human glioma-associated membrane antigen. Monoclonal antibody SZ39 was labeled with 131I using a modified chloramine T method. Each glioma-bearing nude mouse was given 50 microCi/40 micrograms of the experimental agent, 131I-labeled monoclonal antibody, or 50 microCi/46 micrograms of a control agent, 131I-labeled monoclonal antibody C50, an antibody against colon cancer. Single-photon emission computed tomography (SPECT) was performed every 24 hours in the first week after administration. Glioma-bearing nude mice were killed in groups of 3 at 24 hours and daily up to 72 hours. The ratio of radioactivity uptake in glioma to normal organs was calculated. After administration of the labeled SZ39, glioma was visualized with SPECT on days 1 to 7, particularly at 72 hours. There was no accumulation of radioactivity in glioma with the labeled C50 antibody. All glioma-organ ratios increased with time. At 72 hours, the ratio of glioma to brain was 22.46 and of the other organs was 2.64 on average. SZ39 had a relatively low endocytosis rate and was favorable for 131I labeling. These characteristics were helpful to reduce free 131I in the blood and reduce the uptake by other organs. The results suggest that 131I-labeled SZ39 selectively accumulates in glioma, representing a potential strategy for SPECT imaging of these lesions.

Adult↗

PubMed1996

DNA damage, micronucleus formation, and cell death from 125I decays in DNA.

CHO cells were pulse-labeled with 125I-iododeoxyuridine, harvested 30 min or 5 h after labeling, and stored at -196 degrees C for accumulation of 125I decays. The 30- min groups yielded low-LET survival curves (large shoulder, D0 136 decays/cell); 5-h groups showed a high-LET pattern of cell killing (no shoulder, D0 45 decay/cell). Surprisingly, the shift in 125I action was abolished in cells exposed to HAT medium; both 30-min and 5-h cell groups exhibited high-LET-type killing (no shoulder, D0 52 decays/cell). The striking difference in cell death was not accompanied by any change in induction or repair of DNA DSBs, but the pattern of micronucleus formation (and by implication chromosome damage) did parallel 125I-induced cell death. These findings suggest that cell killing may not be directly linked to the absolute number of DNA DSBs and that damage to higher-order genome structures may be an important factor in radiation-induced cell death.

Animals↗

PubMed1996

[Ion-selective microelectrodes: principle and application of in vivo measurements of ionic concentrations in cochlear endolymph].

OBJECTIVE: To introduce the method of making neutral carrier ion-selective microelectrode and use it for in vivo measurement of ionic concentrations in cochloear endolymph. METHODS: GG-17 glass capillaries with 1.85 mm O.D. were rinsed extensively and dried in an oven. Two capillaries were parallelly connected and pulled with microelectrode puller to make a double-barreled micropipette. One barrel was back-filled with ion exchanger and internal reference solution, which served as ionic potential electrode, while the other barrel filled with 150 mmol/L KCL as reference electrode. Each barrel of microelectrode was connected to differential electrometer via Ag-AgCl wire and output was recorded on a three-channel recorder. Every ion-selective microelectrode was calibrated in a series of standard solutions to determine the required characteristics. Twenty healthy guinea pigs with normal hearing were anesthetized and were artificially respired through the tracheal canal after the intramuscular injection of suxamethonium chloride. The tympanic bulla was exposed and a double-barreled ion-selective electrode was inserted into the scala media through the round window and basilar membrane. The ionic potentials and endocochlear potentials (EP) were simultaneously recorded from the basal turn of the cochlea. Ionic concentrations were then calculated by Nicolsky-Eisenman equation. RESULTS: The concentrations of potassium, sodium and calcium ions in the cochlear endolymph were 146.3 +/- 11.8 mmol/L, 0.36 +/- 0.22 mmol/L and 16.2 +/- 5.7 micromol/L, respectively. CONCLUSIONS: The neutral carrier ion-selective microelectrode made with the above method is reliable and therefore can be used for accurately measuring the ionic concentrations of microenvironment in vivo continuously and transiently.

Animals↗

PubMed1996

[Long-term investigation of closed reduction of congenital hip dislocation in children with modified frog-leg cast].

From 1978 to 1983, closed reduction and fixation with frog-leg cast were used to treat congenital hip dislocation in children in our hospital. Sixty-two patients with such hip dislocation were treated by these methods. Among them 38 patients under 3 years of age were followed up for 12 to 16 years (mean 13 years). Encouraging results were obtained and the reduction rate was 97.9%. This treatment revealed that after closed reduction the fixation and the slight movement of the femoral head in the cast under the fixation are a self-remould action that may promote the growth of the acetabulum and the femoral head resulting in normal development of the hip.

Casts, Surgical↗

PubMed1995

Impaired motor coordination correlates with persistent multiple climbing fiber innervation in PKC gamma mutant mice.

It is generally believed that a smooth execution of a compound movement, or motor coordination, requires learning of component movements as well as experience-based refinement of the motor program as a whole. PKC gamma mutant mice display impaired motor coordination but intact eyeblink conditioning, a form of component movement learning. Cerebellar long-term depression, a putative cellular mechanism for component motor learning, is also unimpaired. Thus, PKC gamma mutant mice are defective in refinement of the motor program. In the accompanying paper, we demonstrate that innervation of multiple climbing fibers onto Purkinje cells persists in adulthood in these mutant mice. We propose that this defective elimination of surplus climbing fibers underlies motor discoordination.

Animals↗