Biomedical subjects

Y Zhou

Publications and source records attributed to Y Zhou.

At least 685 records · Page 38Linked to original sources

PubMed1996

Effects of the nitro-group on the mutagenicity and toxicity of some benzamines.

The Ames Salmonella/microsomal assay was employed to test the mutagenicity of some benzamines (aniline, and o- and p-phenylenediamine) and their nitro-derivatives (p-nitroaniline, 2-nitro-p-phenylenediamine, 3- and 4-nitro-o-phenylenediamine), using strains TA98 and TA100 and their nitroreductase-deficient mutants, TA98NR and TA100NR, in the presence and absence of rat S9 mix. The addition of the nitro-group to benzamine molecules converted them into direct mutagens. Furthermore, the position of the nitro-group affected their mutagenic activities. Cytotoxicity testing with Chinese hamster ovary cells (CHO-K1) showed that the presence of the nitro-group in these compounds had no specific effect on toxicity. The test compounds all showed a dose-related increase in inducing chromosomal aberrations in CHO cells. However, the presence of the nitro-group did not affect potency in inducing chromosomal aberrations. Compounds containing the nitro-group had higher initial oxidation potentials and dipole moments (mu) than their nonnitro-containing counterparts. The mutagenicity and toxicity of these compounds were not related to physico-chemical properties, including oxidation potential, energy difference (deltaE) between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO), ionization potential (I.P.), and mu.

Aniline Compounds↗

PubMed1996

Preliminary report on treatment of bone tumors with microwave-induced hyperthermia.

Between July, 1992, and February, 1995, 62 patients with various bone tumors were treated with microwave-induced hyperthermia. The series had 47 cases of malignant tumors and 15 cases with benign tumors; most of the tumors occurred at or near knee joints (53/62 = 85.4%). The surgical procedure consisted of separating the tumorous segment from surrounding normal tissues with a safe margin, cooling the normal tissues (including the vital neurovascular bundle and the intrajoint structures) with a water circulation system while heating the tumor simultaneously with the microwave antenna array, and providing an adequate soft-tissue cover for the dead bone. The tumor core temperature and the surface temperature reached 108 and 65 degrees C, respectively. The duration of microwave irradiation was usually 40-50 minutes. Meanwhile, the temperature of the normal tissues was kept under 39 degrees C. The minimal and maximal periods of clinical observation were 3 months and 36 months, respectively, and the mean follow-up period was 17 months. The 62 cases were evaluated from both oncological and orthopedic points of view. Five cases had local recurrence and required amputation. The 57 other cases had excellent local control. Six malignancy cases died of lung metastasis during a period of 1-2 years. Pathological fracture occurred at devitalized bone in five cases. In most of the cases, the knee joints functioned well, were stable and painless, and had almost full range of motion. Single-photon emission-computed tomography study in 16 cases revealed that revascularization of the devitalized tumorous bone segment could be accomplished in 1 year or more. These results show that the use of microwave hyperthermia for the treatment of bone tumors can be considered to be a definitive operation procedure that is safe and is well tolerated by patients. The oncological and orthopedic results are very encouraging.

Adolescent↗

PubMed1996

Hematologic profile and lymphocyte subpopulations in hemoglobin SC disease: comparison with hemoglobin SS and black controls. The Transfusion Safety Study Group.

Compared with subjects with homozygous SS disease (Hb SS), persons with hemoglobin SC (Hb SC) are known to have a more gradual loss of splenic function, a lower incidence of bacterial infections, and fewer end-organ failures. We studied hematological indices and lymphocyte subpopulations of 27 Hb SC subjects and compared them with 173 Hb SS patients and 131 black controls. Hb SC patients had higher hemoglobin levels than Hb SS subjects, lower total leukocyte, granulocyte, monocyte, and lymphocyte counts. Platelets decreased with age but not significantly, instead of increasing as among Hb SS patients. Mononuclear cells were generally similar to controls with the exception of CD8+HLA-DR+ counts resembling Hb SS. Hematologic changes in Hb SC are limited to moderate granulocytosis in children and adults, mild monocytosis in adults, and increased activation of just one lymphocyte subset among those measured.

Adolescent↗

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

Manipulation of Components of Context: The Context Shift Effect and Forgetting of Stimulus Attributes

Seventy-two Sprague-Dawley rats were used to investigate the multidimensional features of the context shift effect and the forgetting of stimulus attributes in a Pavlovian differential fear conditioning paradigm. One day after training, a change in either conditioning box or room context resulted in substantial decrements in performance similar to that induced by a shift of both box and room contexts. Two weeks after training, a shift of either box or room context exerted no significant detrimental effects on responding. However, a combined shift of both box and room contexts still induced a severe performance deficit. These results suggest that changes in various components of the stimulus context can result in similar retention deficits, that several aspects of stimulus attributes are forgotten over a delay, and that changing several aspects of the stimulus complex can synergistically impair performance.

Journal Article↗

PubMed1996

Concentration of rare earth elements, As, and Th in human brain and brain tumors, determined by neutron activation analysis.

Toxic elements As and Th, six rare-earth elemental profiles of brain tumor tissues from 16 patients of astrocytomas (grade I-III), and normal human brain tissues of 18 male, age-matched autopsies serving as controls have been studied by radiochemical neutron activation analysis. P-204 [di(2-ethylhexyl) phosphate] extraction chromatography column was used for group separation of rare-earth element (REE) by one step. Compared with the normal brain tissues, the analytical results showed that the concentrations of Th, La, Ce, Gd, and Lu were significantly higher in tumor tissues (P < 0.01 or 0.001). The possible effects of REE on tumor cell were discussed.

Adult↗

PubMed1996

Regulation of kappa opioid receptor mRNA in the rat brain by "binge' pattern cocaine administration and correlation with preprodynorphin mRNA.

We previously reported that 'binge' pattern administration of cocaine elevates preprodynorphin (ppDyn) mRNA in the caudate-putamen of rats. The present study confirms this finding. In addition, we report here that "binge' pattern administration of cocaine leads to a significant decrease in the mean level of kappa opioid receptor (KOR) mRNA in the substantia nigra, with no significant change in the mean level of KOR mRNA in the caudate-putamen. The decrease in KOR mRNA in the substantia nigra after 3 day or 14 day 'binge' administration of cocaine was comparable to the increase in ppDyn mRNA in the caudate-putamen. While there was no significant change in the mean levels of KOR mRNA in the caudate-putamen following cocaine administration, there was a positive within animal correlation between the levels of ppDyn mRNA and KOR mRNA in the caudate-putamen, both in animals administered saline and in animals receiving 'binge' cocaine for 14 days. Finally, mean levels of ppDyn or KOR mRNA in cocaine treated rats were not different from saline treated controls following a 10 day withdrawal from 14 days of 'binge' cocaine administration. The results provide evidence of regulation of KOR mRNA by cocaine in the substantia nigra.

Animals↗

PubMed1996

Modulation of CRF-R1 mRNA in rat anterior pituitary by dexamethasone: correlation with POMC mRNA.

Glucocorticoids have been shown to decrease CRF receptor binding in the anterior pituitary. To determine whether glucocorticoids or CRF peptide modulate CRF-R1 gene expression, CRF-R1 mRNA levels in rat pituitary and brain were measured after administration of a synthetic glucocorticoid, dexamethasone (DEX) or rat/human CRF (r/hCRF), using a sensitive solution hybridization RNase protection assay. DEX (400 micrograms/day) or r/hCRF (100 micrograms/kg/day) was administered twice daily for 5 days to male rats. DEX treatment caused a significant decrease in CRF-R1 mRNA levels in the anterior pituitary. Also, a significant positive correlation was found between CRF-R1 and POMC mRNA levels in the anterior pituitary of the individual animals: levels of both mRNAs were reduced by DEX. However, r/hCRF treatment had no significant effect on CRF-R1 mRNA levels in the anterior pituitary. In extrahypothalamic brain regions, mRNA levels of CRF-R1 did not change following either DEX or r/hCRF administration. Our data suggest that in addition to POMC and CRF genes, CRF-R1 gene may also be subject to negative feedback control by glucocorticoids.

Amygdala↗

PubMed1996

Inflammatory cytokines in animal health and disease.

Inflammatory cytokines, including tumor necrosis factor (TNF), interleukin-1 (IL-1), IL-6 and IL-8, are rapidly induced early in a disease or injury process. They mediate and modulate myriad healing processes but, if overexpressed, may exacerbate the severity of a disease condition. In order to test this concept and to establish a foundation for the role of inflammatory cytokines in the pathogenesis of gram-negative bacterial infections in the respiratory tract of animals, the patterns of inflammatory cytokine expression were determined in experimental porcine pleuropneumonia. We observed that IL-1 and IL-6, but not TNF, were rapidly and dramatically elevated in the lavage fluid of the lung within 24 h of infection. The increased levels of IL-1 might contribute to increased severity of disease, but elevated IL-6 levels were consistent with a protective acute phase response. Additional studies were performed to examine the hypothesis that IL-4 expression later in infection might be involved in turning off the inflammatory response and promoting an antigen-specific humoral immune response. Interleukin-4 efficiently suppressed inflammatory cytokine production in alveolar macrophages. Its expression was induced in peripheral blood mononuclear cells by TNF, IL-4, and by reexposure to a specific antigen. To obtain the maximum amount of information on the role of inflammatory cytokines in animals of veterinary significance it will be useful to perform studies in species such that evolutionary relatedness will allow widespread application of the findings. Furthermore, the variety of molecules involved in inflammatory cytokine regulation will require much more extensive investigations of the relevant enzymes, inhibitors and receptors in veterinary species. Finally, the complexity and redundancy of immune defenses in animals mean that attempts to modulate health status through manipulation of inflammatory cytokines must be performed with caution and that a multiplicity of processes will be affected.

Animal Diseases↗

PubMed1996

Age-dependent spatial memory deficits in transgenic mice expressing the human mid-sized neurofilament gene: I.

Previous studies have revealed that the transgenic mouse line expressing the human neurofilament-mid-sized (NF-M) gene evidences age-dependent and cell-specific pathological neurofibrillary accumulation in the central nerve system. In the current study, we investigated the learning and memory processes of NF-M transgenic mice at 3 and 8 months of age in a modified Morris water maze using a series of tasks including those primarily related to reference memory (i.e., spatial learning, reversal learning and probe trials) and to working memory (i.e., matching to sample tasks with or without delays). At 3 months of age, NF-M transgenic mice were indistinguishable from age- and litter-matched non-transgenic wild-type controls on any of the tests of reference and working memory. At 8 months of age, however, the NF-M transgenic mice exhibited significantly poorer performance than the age- and litter-matched wild-type control mice on both reference and working memory tasks. Immunohistological study of the brains of the 8-month-old NF-M transgenic mice revealed spherical and tangle-like neurofilamentous accumulation in their cerebral cortices. These results suggest that NF-M transgenic mice express both age-related histopathological changes and age-dependent learning and memory deficits. Whether NF-M transgenic mice exhibit even more severe behavioral impairments when they become aged is currently under study.

Aging↗

PubMed1996

Toxigenic molds in water-damaged buildings: dechlorogriseofulvins from Memnoniella echinata.

An investigation of a cluster of cases of pulmonary hemosiderosis in infants in Cleveland, OH, led to the isolation of many isolates of Stachybotrys atra and two isolates of a related toxigenic fungus, Memnoniella echinata. M. echinata produces two cytotoxic trichothecene mycotoxins, trichodermol (1a) and trichodermin (1b), as well as several griseofulvins. Dechlorogriseofulvin (2a) and epidechlorogriseofulvin (2b) were the major compounds isolated. This is the first report of a fungus outside the Penicillium genus producing griseofulvins.

Griseofulvin↗

PubMed1996

Actions of neurotoxic beta-amyloid on calcium homeostasis and viability of PC12 cells are blocked by antioxidants but not by calcium channel antagonists.

The fragment of beta-amyloid comprised of amino acids 25-35 induces a rapid, concentration-dependent increase in cytosolic free calcium levels in suspensions of PC12 neuronal cells. This action of beta-amyloid 25-35 is not altered by pretreatment with the calcium channel blockers nifedipine or cobalt, with the depleter of intracellular calcium stores cyclopiazonic acid, or with the phospholipase C inhibitor neomycin. However, the effects of beta-amyloid 25-35 on cytosolic free calcium are absent in calcium-free buffer and are blocked by the antioxidant lazaroid U-83836E and by vitamin E. beta-Amyloid 25-35 is also neurotoxic and produces a concentration-dependent reduction in the viability of PC12 cells in culture. The neurotoxic action of beta-amyloid is blocked by U-83836E and vitamin E but not by nifedipine or cobalt. These data indicate that both the disruption of calcium homeostasis and the reduction of cell viability produced by beta-amyloid in PC12 cells are mediated by free radical-based processes.

Amyloid beta-Peptides↗

PubMed1996

Identification and characterization of autosomal genes that interact with glass in the developing Drosophila eye.

The glass gene encodes a zinc finger, DNA-binding protein that is required for photoreceptor cell development in Drosophila melanogaster. In the developing compound eye, glass function is regulated at two points: (1) the protein is expressed in all cells' nuclei posterior to the morphogenetic furrow and (2) the ability of the Glass protein to regulate downstream genes is largely limited to the developing photoreceptor cells. We conducted a series of genetic screens for autosomal dominant second-site modifiers of the weal allele glass3, to discover genes with products that may regulate glass function at either of these levels. Seventy-six dominant enhancer mutations were recovered (and no dominant suppressors). Most of these dominant mutations are in essential genes and are associated with recessive lethality. We have assigned these mutations to 23 complementation groups that include multiple alleles of Star and hedgehog as well as single alleles of Delta, roughened eye, glass and hairy. Mutations in 18 of the complementation groups are embryonic lethals, and of these, 13 show abnormal adult retinal phenotypes in homozygous clones, usually with altered numbers of photoreceptor cells in some of the ommatidia.

Animals↗

PubMed1996

Viral etiology of acute childhood encephalitis in Beijing diagnosed by analysis of single samples.

OBJECTIVE: To understand the viral etiology of acute childhood encephalitis in Beijing. METHODS: Ninety-seven Chinese children (between 7 months and 13 years of age) with acute encephalitis were retrospectively investigated. They were treated in Beijing Children's Hospital between June, 1991, and October, 1994. Different serologic methods (immunofluorescence assay, enzyme-linked immunosorbent assay, solid phase reverse immunosorbent test) were used for detection of IgM antibody to enteroviruses, herpesviruses, mumps, measles, rubella and Japanese encephalitis virus. The viral DNA of six herpesviruses was detected by polymerase chain reaction. RESULTS: Viral etiology was identified in 35 of 97 (36.0%) cases. The most frequently identified pathogens were enteroviruses (15; 15.4%), followed by mumps (7; 7.2%), rubella (6; 6.1%), Japanese encephalitis virus (5; 5.1%), human herpesvirus 6 (2; 2.0%), herpes simplex virus (2; 2.0%) and Epstein-Barr virus (1; 1.0%). IgM antibody in cerebrospinal fluid was detected for enterovirus, mumps and rubella viruses. CONCLUSIONS: Enteroviruses were the most frequent viral pathogens of acute childhood encephalitis in Beijing. Detection of IgM in cerebrospinal fluid may be useful for diagnosis in certain cases of viral encephalitis.

Acute Disease↗

PubMed1996