[Study on the effects of noise on hypertension and hyperglycemia among occupational workers].

Objective: To study the effect of noise on hypertension and hyperglycemia among occupational workers. Methods: Total 670 workers in an automobile manufacturing company were selected as the subjects of physical examination in 2017. According to the noise exposure or not, the subjects were divided into control group (no noise exposure) 143 and contact group (noise exposure) 527. Questionnaire survey and physical examination were conducted. The measurement data were analyzed by t-test, and the count data and grade data were analyzed by χ(2) test. The influence of noise on blood glucose, heart rate, blood pressure and other indicators was analyzed by logistic regression, and the OR and 95%CI of each risk factor were calculated. Results: The average age of the control group and the contact group was no significant difference (P>0.05) . There were 139 (20.7%) cases of high systolic pressure, 154 (23.0%) cases of high diastolic pressure, 63 (9.4%) cases of hyperglycemia, 29 (4.3%) cases of tachycardia. Compared with the control group, there were significant differences in systolic blood pressure, diastolic blood pressure and blood glucose in the contact group (P<0.05) . Compared with the control group, the systolic blood pressure, diastolic blood pressure and blood glucose of the subjects in the corresponding age contact group increased significantly (P<0.05) . The years of noise exposure were protective factors for systolic and diastolic blood pressure (OR=0.970, 0.973) . Conclusion: Noise exposure may increase blood pressure and blood sugar of occupational workers, but the effect on heart rate can not be determined.

Effect of level of metabolizable protein on milk production and nitrogen utilization in lactating dairy cows.

The objective of this study was to investigate the effects of the level of metabolizable protein (MP) on milk production and nitrogen utilization in Chinese Holstein dairy cows. Forty multiparous dairy cows (body weight = 590 kg; days in milk = 135; average milk yield = 30.2 kg/d) were assigned to treatments randomly within groups based on days in milk and milk production. Animals were offered diets with different levels of MP: 8.3% (diet A), 8.9% (diet B), 9.7% (diet C), and 10.4% (diet D) of dry matter. The MP level in diet A was designed to meet the current Chinese National Station of Animal Production and Health guidelines, whereas that in diet D was based on the National Research Council (2001) model. The experiment lasted for 7 wk. Milk yield and milk composition (fat, protein, and lactose) were recorded, and urea nitrogen concentrations in serum, urine, and milk were measured during the experiment. Milk yield and milk protein percentage increased as the MP increased up to 9.7% of dry matter, and then leveled off. Concentrations of nitrogen in urine, serum, and milk increased linearly as the amount of MP was increased, indicating decreased efficiency of nitrogen utilization. Milk lactose percentage and total solids percentage showed no significant differences among the 4 diets. We concluded that the optimal dietary MP level was at 9.6% of dry matter for Chinese Holstein dairy cows producing 30 kg of milk per day.

Cytogenetic analysis of mouse oocytes and one-cell zygotes as a potential assay for heritable germ cell aneuploidy.

Assays are needed for detecting chemically-induced aneuploidy, for investigating the mechanisms of aneuploidy production, and for obtaining heritable germ cell data that can be used to formulate human risk estimates. In this report, we describe the results of experiments designed to study aneuploidy in metaphase II (MII) oocytes induced by intraperitoneal (i.p.) or oral dosages of colchicine, and to investigate the proportion of aneuploid oocytes transmitted to one-cell (1C) zygotes following oral administration of colchicine immediately following HCG. The proportions (and percentages) of hyperploid MII oocytes were: 1/606 (0.2), 37/504 (7.3), 152/731 (20.8) and 75/319 (23.5) for control, 0.2, 0.3 and 0.4 mg/kg, respectively for i.p. administration of colchicine; and 3/216 (1.4), 8/539 (1.5), 81/511 (15.9), 71/398 (17.8) and 98/391 (25.1) for control, 1.0, 2.0, 3.0 and 4.0 mg/kg, respectively for oral administration of colchicine. The proportions of hyperploid 1C zygotes were 2/327 (0.6), 21/389 (5.4), 62/435 (14.3) and 69/438 (15.8) for control, 2.0, 3.0 and 4.0 mg/kg, respectively for oral colchicine. The proportions of hyperploid MII oocytes and 1C zygotes were significantly higher (Chi-square, P less than 0.01) at each i.p. or oral dose (except 1.0 mg/kg oral) than in the controls. The frequencies of hyperploidy induced by oral doses of colchicine were greater in MII oocytes than in 1C zygotes. We also found that the frequency of developmentally delayed and polyploid 1C zygotes increased with the dose of oral colchicine. Developmentally delayed zygotes contained male-derived chromosomes and female-derived fragmented pronuclei and pronuclei with decondensed chromosomes. These results indicate that higher doses of oral colchicine are needed to induce comparable levels of aneuploidy found after i.p. administration, and that aneuploid oocytes are fertilized and reach first cleavage metaphase. In addition, colchicine induces a spectrum of events including aneuploidy, polyploidy and developmentally delayed oocytes and zygotes.

Analysis of mouse metaphase II oocytes as an assay for chemically induced aneuploidy.

Our initial objective was to develop an in vivo mammalian, female aneuploid assay that is consistent, time efficient, and that yields a large number of oocytes amenable to objective analyses. Subsequently, we desired to use such an assay for identifying chemicals and dosages that could increase the incidence of aneuploidy in mouse metaphase II oocytes. The experimental protocol involved superovulating CD-1 mice with PMS; HCG was given 48 h later. At the time of HCG injection, different dosages od diethylstilbestrol diphosphate, cadmium chloride, chloral hydrate, or colchicine were injected intraperitoneally. 17 h later, oocytes were collected and fixed prior to C-banding the chromosomes. The procedure required about 3 h to process oocytes from 25 mice and yielded over 100 analyzable metaphase II oocytes. Colchicine was the only compound tested that resulted in a statistically significant (P less than 0.01) increase in hyperploid (N greater than 20) oocytes over controls. The incidence of hyperploid oocytes in the colchicine group was 2/167, 1/182, 21/220, and 38/202, for control, 0.1 mg/kg, 0.2 mg/kg, and 0.3 mg/kg, respectively. This assay appears sensitive for aneuploidy detection but requires further validation.

Substance P-immunoreactive nerves in the rat kidney.

An indirect immunohistochemical method in which an avidin-biotinylated horseradish peroxidase complex is bound to the secondary antibody was used to visualize substance P-immunoreactive (SPI) nerves in the rat kidney. Rats were perfused with 2% paraformaldehyde + 0.15% picric acid in 0.1 M phosphate buffer, then transferred to the buffer. After 24-48 h, the kidneys were sectioned with a Vibratome at 200 or 300 micron and incubated in the primary antiserum for 18 h at room temperature. A dense plexus of SPI nerves innervates the rat renal calyx. A small proportion of intrarenal SPI axons innervates interlobular arteries and afferent arterioles, but most perivascular SPI axons terminate on interlobar and arcuate arteries. The densest plexuses are located on segments of interlobar arteries near the hilus of the kidney. Some of these axons probably are nociceptive; others may be chemo- or baroreceptive.

Vasoactive intestinal peptide-immunoreactive nerves in the rat kidney.

An indirect immunohistochemical method in which an avidin-biotinylated horseradish peroxidase complex is bound to the secondary antibody was used to visualize vasoactive intestinal peptide-immunoreactive (VIPI) nerves in the rat kidney. Rats were perfused with 4% paraformaldehyde or 2% paraformaldehyde + 0.15% picric acid in 0.1 M phosphate buffer, then transferred to the buffer. After 24-48 hours, the kidneys were sectioned with a Vibratome at 200 or 300 micron and incubated in the primary antiserum for 18 hours at room temperature. A sparse plexus of VIPI nerves innervates the rat renal calyx. Some VIPI nerves innervate interlobar arteries and each succeeding segment of the arterial tree including afferent arterioles, but most innervate arcuate and interlobular arteries. VIPI axons do not innervate each arcuate artery or each interlobular branch of an arcuate artery with equal density. Although some axons follow each interlobular branch, most form a dense plexus on only one or two branches. Therefore, most VIPI nerves in the rat kidney innervate a restricted segment of the renal arterial tree. These nerves may be efferent and may selectively dilate arcuate and smaller arteries, or they may be afferent and may sense local changes in mechanical or chemical parameters.

Cytogenetic technique for mouse metaphase II oocytes.

The acquisition of cytogenetic data from mammalian oocytes has required considerable time and expense, since only a relatively small number of oocytes could be processed from three to four animals daily. The availability of a procedure that would facilitate fixation and preparation of air-dried slides from 25-30 superovulated mice within a 3-h period would enhance development of germ cell cytogenetic data by reducing technician time and animal maintenance expense. We present such a procedure for mouse metaphase II oocytes. Mice were superovulated and the oocytes collected were fixed en masse prior to making air-dried slides. Chromosomes were subsequently C-banded to enhance objective cytogenetic analysis. The reliability of the procedure was determined by harvesting 44,814 oocytes from 1,875 mice over a 9-month period and calculating the proportion of cells cytogenetically analyzed to those not analyzed. Cytogenetic analysis of oocytes is an assay for chemicals (and other agents) capable of inducing numerical and structural chromosomal aberrations.

Aneuploidy determination in C-banded mouse metaphase II oocytes following cyclophosphamide treatment in vivo.

The ability of cyclophosphamide (CYC) to induce aneuploidy in metaphase II oocytes of mice was evaluated. Various dosages (50, 100, 150, 250 and 350 mg/kg body weight) of CYC were injected intraperitoneally prior to induced ovulation. Chromosomes were C-banded to allow a more accurate counting of chromosomes and chromatids, and analysis of structural aberrations. Structural aberrations were not observed. Although the incidence of aneuploid oocytes in the treated groups was greater than that in the control group, the differences were not statistically significant. This result was unlike those of other relevant reports and several plausible explanations for such a disparity are discussed.

Differential sensitivity of mouse oocytes to colchicine-induced aneuploidy.

Unpublished results from our laboratory showed that colchicine increased the incidence of hyperploid mouse metaphase II (MII) oocytes when injected at the same time as human chorionic gonadotrophin (HCG). The objective of the present study was to determine whether the time of administering colchicine influenced the incidence of aneuploidy in MII oocytes. CD-1 mice were given pregnant mare's serum (PMS) and 48 hr later, HCG. An intraperitoneal injection of 0.2 mg/kg colchicine was given at +4, +2, 0, -2, or -4 hr relative to HCG. Oocytes were collected 17 hr post-HCG and processed, and chromosomes were subsequently C-banded. The percentage of hyperploid oocytes was 0.77, 2.56, 5.71, 7.79, 3.54, and 2.70 for control, +4, +2, 0, -2, or -4 hr pre/post-HCG, respectively. Chi-square analyses of these data demonstrated that colchicine significantly increases the proportion of aneuploid oocytes, and that the relative sensitivity of colchicine-induced aneuploidy depends upon the time that this drug is administered relative to HCG.