甲状腺功能减退对雄性大鼠精子活动度的影响

目的 探讨甲状腺功能减退(甲减)对雄性大鼠精子活动度的影响.方法 健康雄性Wistar大鼠20只,体质量200～240 g,按体质量随机分为2组:生理盐水(对照)组和甲减组(按1 ml/100 g体质量灌服0.1％丙硫氧嘧啶),每组10只,共60d,每3天称体质量.灌胃结束次日处死大鼠,取全血,分离血清.放射免疫法检测血清中甲状腺激素水平:总三碘甲状腺素原氨酸(T3)、总甲状腺素(T4)、促甲状腺激素(TSH).取附睾游离精子,WLJY-9000型伟力彩色精子质量检测系统测定精子运动参数:平均路径速度、直线速度、前向性、侧摆幅度、精子密度、曲线速度、直线性、摆动性、平均移动角度、鞭打频率.结果 灌胃第30、60天甲减组大鼠体质量[(239.00±15.02)、(232.67±17.86)g]均低于对照组[(298.20±12.15)、(344.00±13.73)g,t值分别为7.704、11.380,P均＜0.05].甲状腺激素水平:甲减组大鼠T3[(373.3±101.3)ng/L]、T4[(4.00±0.89)×103 ng/L]水平低于对照组[(1000.0±273.5)ng/L、(44.33±7.84)×103 ng/L,t值分别为5.262、2.520,P均＜0.05],TSH[(5.77±0.89)×103 U/L]水平高于对照组[(1.87±0.70)×103 U/L,t=8.413,P＜0.05].精子参数:甲减组平均路径速度[(27.45±1.59)μm/s]、直线速度[(21.08±1.10)μm/s]、前向性[(70.53±3.48)％]、侧摆幅度[(1.96±0.26)μm]高于对照组[(24.38±2.59)μm/s、(17.99±2.06) μm/s、(65.93±2.71)％、(1.53±0.27)μm,t值分别为2.687、2.404、2.420、3.175,P均＜0.05].甲减组精子密度[(5.07±0.74)109/L]低于对照组[(8.76±1.01) 109/L,t=6.463,P＜ 0.05].甲减组曲线速度[(52.83±5.56)μm/s]、直线性[(38.58±3.41)％]、摆动性[(52.64±3.24)％]、平均移动角度[(64.21±6.71)度/s]、鞭打频率[(8.93±0.62)Hz]与对照组[(49.92±6.43)μm/s、(36.52±2.73)％、(52.49±3.49)％、(62.77±7.34)度/s、(9.32±0.61)Hz]比较差异无统计学意义(t值分别为0.805、1.089、0.037、0.341、1.033,P均＞0.05).结论 甲状腺功能减退可影响雄性大鼠精子活动度,降低精子密度,损害大鼠生殖系统.     

吸烟对男性精子形态 精子DNA完整率和精子顶体完整率的研究

目的：研究吸烟对男性精子形态、精子DNA完整率[用精子DNA断裂指数（ DFI）表示]及顶体完整率的影响。方法回顾性分析来该中心就诊的1500例男性患者（1300例吸烟者及200例未吸烟者）,按每天吸烟量分为A1组500例,＞20支／d;A2组600例,10-20支／d;A3组200例,1-9支／d。 B组200例,0支／d,作为对照组。结果精子正常形态随着每天吸烟量的增加而下降,各组间两两比较差异有统计学意义（ P＜0．05）。精子DNA完整率随着吸烟量的上升而降低（ DFI升高）,各组间两两比较差异有统计学意义（ P＜0．05）。精子顶体完整率随吸烟量上升而下降,各组间两两比较差异有统计学意义（ P＜0．05）。结论随着每天吸烟量增加精子正常形态、精子DNA完整率及精子顶体完整率均降低,不利于男性生殖健康。     

Aging and pancreatic exocrine function: studies in conscious male rats

Changes in pancreatic exocrine function in young (6- and 12-month-old) and old (24- to 27-month-old) male Fischer (F-344) rats were examined. Rats were prepared with cannulae draining bile and pancreatic juice separately and with duodenal and right jugular vein cannulae. Experiments were conducted between the third and the seventh postoperative day in conscious rats. Bile and pancreatic juice were returned to the intestine during both the recovery period and between experiments. Pancreatic responses to endogenous [bile-pancreatic juice (BPJ) diversion from the intestine] and exogenous stimulation [0.086, 0.432, and 1.728 nmol/kg secretin and 0.033, 0.167, and 0.667 nmol/kg cholecystokinin-octapeptide (CCK-8)] were determined. Basal secretions of fluid, bicarbonate, and protein were not affected by aging. The pancreatic responses of fluid and bicarbonate secretion to BPJ diversion or secretin were unaffected by aging. However, the increment of protein secretion in response to BPJ diversion and the largest dose of CCK-8 was attenuated in old rats. It appears the duct cell function is hardly affected by aging, but that the reserve capacity for protein secretion in response to stimulation may decrease in old rats.     

慢性氟中毒对大鼠精子活动度的影响

目的 探讨慢性氟中毒对大鼠精子活动度的影响,为氟的生殖毒性研究提供实验依据.方法 健康雄性Wistar大鼠32只,体质量150～180 g,按体质量随机分为4组:生理盐水(对照)组、低、中、高氟组(100、200、300mg·kg~(-1)·d~(-1)NaF),灌胃染毒90 d,每天称体质量.染毒结束后处死大鼠,摘取肝脏、肾脏、睾丸,称质量并计算脏器系数;取附睾游离精子,WLJY-9000型伟力彩色精子质量检测系统测定精子运动参数.结果 染毒第30天低、中氟组大鼠体质量[(235.00±14.56)、(235.44±24.99)g]高于高氟组[(206.00 ±18.16)g,P均<0.05)];第60、90天组大鼠体质量比较差异无统计学意义(F值分别为0.578、1.893,P均>0.05).大鼠肝脏系数、肾脏系数、睾丸系数组间比较差异无统计学意义(F值分别为2.148、0.907、1.801,P均>0.05).精子运动参数,平均路径速度(VAP)高氟组[(25.04 ±4.59)μm/s]较对照组[(20.22 ±3.29)μm/s]升高;直线速度(VSL)低、中、高氟组[(18.82 ±3.19)、(17.84 ±4.54)、(16.46 ±2.63)μm/s]较对照组[(12.48 ±1.73)μm/s]升高;直线性(LIN)低、中、高氟组[(23.84±1.58)%、(24.99±3.37)%、(26.75 ±5.07)%]较对照组[(33.29±4.00)%]降低,摆动性(WOB)中、高氟组[(47.03 ±3.98)%、(49.21±7.73)%]较对照组[(38.09 ±0.48)%]升高;平均移动角度(MAD)低氟组[(68.29 ±5.71)度/s]较对照组[(81.57 ±8.44)度/s]降低;鞭打频率(BCF)高氟组[(11.47 ±0.61)次/s]较对照组[(9.49 ±0.34)次/s]升高;精子密度(p)低、中氟组[(1.26 ±0.24)×10~9、(1.84 ±0.50)×10~9/L]较对照组[(3.94±1.10)×10~9个/L]降低(P均<0.05);曲线速度(VCL)、前向性(STR)、侧摆幅度(ALH),组间比较差异无统计学意义(F值分别为0.264、2.209、1.667,P均>0.05).结论 慢性氟中毒可影响大鼠精子活动度.降低精子密度.损害大鼠生殖系统.     

Aging increases mitochondrial DNA damage and oxidative stress in liver of rhesus monkeys

While the mechanisms of cellular aging remain controversial, a leading hypothesis is that mitochondrial oxidative stress and mitochondrial dysfunction play a critical role in this process. Here, we provide data in aging rhesus macaques supporting the hypothesis that increased oxidative stress is a major characteristic of aging and may be responsible for the age-associated increase in mitochondrial dysfunction. We measured mitochondrial DNA (mtDNA) damage by quantitative PCR in liver and peripheral blood mononuclear cells of young, middle age, and old monkeys and show that older monkeys have increases in the number of mtDNA lesions. There was a direct correlation between the amount of mtDNA lesions and age, supporting the role of mtDNA damage in the process of aging. Liver from older monkeys showed significant increases in lipid peroxidation, protein carbonylations and reduced antioxidant enzyme activity. Similarly, peripheral blood mononuclear cells from the middle age group showed increased levels in carbonylated proteins, indicative of high levels of oxidative stress. Together, these results suggest that the aging process is associated with defective mitochondria, where increased production of reactive oxygen species results in extensive damage at the mtDNA and protein levels. This study provides valuable data based on the rhesus macaque model further validating age-related mitochondrial functional decline with increasing age and suggesting that mtDNA damage might be a good biomarker of aging.     

Age-related changes in blood and liver lipids of male Wistar rats

The results of this study indicate that the age-dependent plasma cholesterol increase observed in male Wistar rats is correlated with changes in both the distribution of high-density lipoprotein fractions and the storage of hepatic cholesterol. Specifically, the lipoprotein distribution showed a significant increase in the proportion of HDL(1) and a symmetrical decrease in both the HDL(2) and HDL(3) fractions during the 3 month to 18 month age period. There were no significant changes in the very-low density and low-density lipoprotein fractions. The chemical composition of lipoproteins showed many age-related variations, especially in the proportion of cholesteryl ester and in the distribution of HDL subfractions. A study of fatty acyl composition of the major lipid classes showed that, within cholesteryl ester found in liver, there was an increase in the proportion of saturated fatty acids. Polyunsaturated fatty acids increased in the cholesteryl esters found in high-density lipoproteins of older rats. These observations suggest that the age-dependent accumulation of body cholesterol occurs by a reduced catabolism of HDL(1) fraction, and modifications in plasma and liver lipids.     

Hypophysectomy and growth hormone receptors in liver membranes of male rats

The effects of hypophysectomy on GH binding were studied in liver membranes of male rats. Ten days after surgery, the specific binding of [125I]iodobovine GH and of [125I] iodohuman GH was 2- to 3-fold higher in microsomal membranes of hypophysectomized rats than in membranes of control male animals. The number of receptors rather than the affinity of the binding was affected. A nonspecific membrane effect due to hypophysectomy is unlikely since membrane markers such as 5' nucleotidase, galactosyl transferase, and insulin binding were not different in liver membranes of hypophysectomized and control rats. The somatogenic specificity and the subcellular distribution of the binding sites were not altered by hypophysectomy; the number of the GH binding sites were increased in plasma membranes as well as in Golgi fractions. Hypophysectomy in male rats creates a situation where growth failure, absence of circulating GH, and lack of plasma somatomedin activity are associated with increased concentration of liver somatogenic receptors. The latter finding could explain why livers of hypophysectomized rats are more sensitive to GH than those of normal rats.     

Hypogonadism precedes liver feminization in chronic alcohol-fed male rats

Men who chronically abuse alcohol may display a spectrum of endocrine abnormalities including hypogonadism and feminization, with elevated serum estradiol and low serum testosterone. We examined factors that may result in disruption of hepatic sex hormone homeostasis in alcohol-fed male rats and possible consequences of such changes. Rats were fed alcohol-containing or isocaloric diets for 30, 60, and 90 days. In alcohol-fed rats, serum testosterone levels and hepatic activity of 2 androgen-dependent estrogen metabolizing enzymes were reduced (P <.05) at all times, as was activity of androgen receptor. There was also a significant early and progressive decrease in testes/body ratio in alcohol-fed rats. Compared with this early decrease in testosterone-related parameters, there was a significant increase in serum estrogen levels (at 30 and 90 days, 132% and 168% of control values, respectively). An increase in serum ceruloplasmin, an estrogen-responsive liver protein, was apparent at 60 and 90 days, but not at 30 days of alcohol exposure, suggesting that hypogonadism precedes liver feminization. Hepatic estrogen receptor activity was decreased in alcohol-fed rats at 60 and 90 days, the latter despite elevated serum estrogen levels. Hepatic aromatase was slightly increased in alcohol-fed rats, an elevation probably not sufficient to account for observed increases in serum estrogen. Taken together, these data suggest that (1) alcohol induces profound reduction of serum testosterone, resulting in loss of androgen-regulated hepatic functions such as estrogen-metabolizing enzyme activity and activity of androgen receptors; and (2) such alcohol-induced hypogonadism precedes changes in hepatic sex hormone homeostasis and subsequent feminization.     

Aldosterone metabolism in the isolated perfused liver of female and male rats

A sex-dependent metabolism of aldosterone has been reported in intact rats. To further characterize the hepatic elimination of aldosterone and its sex dependence, the metabolism of d-[4-14C]aldosterone was studied in isolated perfused liver from male and female Wistar rats, from male rats castrated 3 weeks before experiments, and from younger male rats (same body weight as the female rats). The livers were perfused at a constant flow rate in a recirculating mode with a hemoglobin-free medium containing aldosterone at initially 1 nM. Perfusate aldosterone was measured by a specific RIA. Total 4-14C radio-activity in perfusate and bile was determined. The perfusate [4-14C]aldosterone radiometabolite concentration was calculated. The radiometabolite pattern in additional experiments was studied by HPLC. The male rats exhibited 10% higher systolic blood pressure (P less than 0.05) and 51% higher fasting values of plasma aldosterone (P less than 0.05) compared to those in the female rats. In female rats the hepatic clearance rate of aldosterone per 100 g BW was 72% higher than that in male rats (11.2 +/- 2.7 to 6.5 +/- 1.8 ml/min: P less than 0.01), and that expressed per g liver wet wt was 75% higher (3.5 +/- 1.0 to 2.0 +/- 0.7 ml/min; P less than 0.01). When female rats were compared to younger male rats with the same body weight, 33% higher hepatic aldosterone clearance rates were still found in female rats (21.0 +/- 5.4 to 15.8 +/- 3.2 ml/min; P less than 0.05), and 51% higher values when expressed per g liver wet wt (3.5 +/- 1.0 to 2.3 +/- 0.5 ml/min; P less than 0.01). No difference in the aldosterone clearance rate was observed in castrated male rats compared to that in noncastrated male rats. 4-14C-Labeled radiometabolite levels accumulated similarly in the perfusate of livers of both sexes. Perfusate 4-14C-labeled radiometabolites after 90 min of perfusion were lower in livers of castrated male rats than in noncastrated male rats (P less than 0.001). The final perfusate 14C-labeled radiometabolite concentration correlated inversely with the total 14C in bile (P less than 0.01). All 14C-labeled radiometabolites detected in perfusate and bile after 90 min were more polar than aldosterone. After enzymatic hydrolysis, some of the metabolites from the male livers cochromatographed with tetrahydro- and dihydroaldosterone, while other fractions remained more polar. Only more polar metabolites were detected in the perfusate and bile of female livers.(ABSTRACT TRUNCATED AT 400 WORDS)     

High-resolution mapping of DNA hypermethylation and hypomethylation in lung cancer

Changes in DNA methylation patterns are an important characteristic of human cancer. Tumors have reduced levels of genomic DNA methylation and contain hypermethylated CpG islands, but the full extent and sequence context of DNA hypomethylation and hypermethylation is unknown. Here, we used methylated CpG island recovery assay-assisted high-resolution genomic tiling and CpG island arrays to analyze methylation patterns in lung squamous cell carcinomas and matched normal lung tissue. Normal tissues from different individuals showed overall very similar DNA methylation patterns. Each tumor contained several hundred hypermethylated CpG islands. We identified and confirmed 11 CpG islands that were methylated in 80-100% of the SCC tumors, and many hold promise as effective biomarkers for early detection of lung cancer. In addition, we find that extensive DNA hypomethylation in tumors occurs specifically at repetitive sequences, including short and long interspersed nuclear elements and LTR elements, segmental duplications, and subtelomeric regions, but single-copy sequences rarely become demethylated. The results are consistent with a specific defect in methylation of repetitive DNA sequences in human cancer.     

Ontogeny of liver somatotropic and lactogenic binding sites in male and female rats

Developmental changes in liver somatotropic (GH) and lactogenic (PRL) binding sites were evaluated in male and female rats from birth to sexual maturity, and compared with growth velocity, plasma GH, PRL, testosterone, and estrogens. The affinity (Ka) and the concentration of these sites were determined from the analysis of equilibrium saturation curves with [125I]bovine GH and [125I]ovine PRL, incubated with liver homogenates. GH receptors rose from 6.4 fmol/mg protein at 8 days of age to 30.3 fmol/mg protein in males and 39.4 fmol/mg protein in females at 28 days. This surge occurred concomitant with the fall of plasma GH observed after birth. It preceded by about 1 week the acceleration of growth velocity and the increase of plasma GH seen at puberty. After the peak of growth velocity (42 days), GH receptors increased steadily until 120 days in females (63.8 fmol/mg protein), whereas in males they reached a concentration of 33.5 fmol/mg protein after a transient decrease to a nadir of 13.3 fmol/mg protein a day 50. From day 8 to day 35, PRL receptors in males remained at a constant level of 10.3 fmol/mg protein, whereas in females they increased progressively from 4.8 to 21.5 fmol/mg protein. Thereafter, in most pubertal males, they became undetectable, whereas plasma testosterone was rising. In contrast, PRL receptors in females increased 3-fold between day 42 (18.9 fmol/protein) and day 50 (50.2 fmol/mg protein). Between days 8 and 120, the Ka of GH and PRL receptors showed no significant changes with age and sex (GH: 0.66 X 10(9) M-1; PRL: 0.97 X 10(9) M-1). In conclusion, the rise of liver GH receptors occurring before puberty in male and female rats may be of importance for the initiation of the pubertal growth spurt. The inverse relationship between plasma testosterone and liver PRL receptors in pubertal male rats suggests that physiological concentrations of testosterone may inhibit PRL receptors. In contrast, in female rats an opposite change of PRL receptors is observed during puberty.     

Aging liver and hepatitis

Chronic liver disease and cirrhosis are the tenth leading causes of death in the United States and results in approximately 25,000 deaths annually. As life expectancy in developed countries has increased, so has the number of elderly patients who have liver disease. With an aging population and chronic liver disease becoming an increasingly significant cause of morbidity and mortality, the various causes for hepatitis will need to be evaluated and available treatments considered, even in elderly population. Common causes for hepatitis in elderly individuals include viral, autoimmune, and drug-induced hepatitis, but evidence for treatment of this population is limited. This article reviews the likely causes of hepatitis in elderly individuals and discusses evidence for treating this population.     

Aging changes in the liver of the male annual cyprinodont fish, Nothobranchius guentheri.

Histological studies were performed on the liver of the male annual cyprinodont fish, Nothobranchius guentheri between 3 and 18 months of age. The very young, but sexually mature fish, showed few changes. Beginning at 4–6 months of age the number of fish exhibiting histological changes increased, but reamined stable to 13–14 months. The prevalent changes were: vacuolization of hepatocytes and nodular degeneration progressing to cyst like formations. At 15–18 months, three new lesions were observed: swirl formations by endothelial cell proliferation, fibrosis with melanin pigmented cells and malignant transformation. Since annual fish have a relatively short lifespan, both in nature and in the laboratory, they have been used as a model for the aging process. Histological studies are critical in establishing aging patterns and allow for broader interpretation of physiological and biochemical changes.     

增龄是雄性大鼠碘对比剂急性肾损伤的促进因素

目的研究年龄对雄性大鼠碘对比剂急性肾损伤（CI．AKI）的影响。方法36只雄性SD大鼠根据月龄分为4月龄组、12月龄组和24月龄组,每组12只,各年龄组大鼠再随机分为正常对照组和对比剂组6个亚组,每组6只。禁水24h后,不同年龄鼠对比剂组大鼠尾静脉注射碘对比剂76％泛影葡胺（10ml／kg）,相应对照组大鼠尾静脉注射等量生理盐水。检测尿肌酐（UCr）、尿N-乙酰-B．D．氨基葡萄糖苷酶（NAG）、血肌酐（SCr）、内生肌酐清除率（Ccr）、肾组织匀浆脂质过氧化物丙二醛（MDA）含量及血管紧张素转换酶（ACE）活性水平。48h后处死动物,观察肾脏的病理改变并检测。肾组织Sp1蛋白表达。结果注射对比剂后48h,24月龄鼠对比剂组SCr水平显著升高（P〈0．01）,且升高幅度超过对照组的25％,Ccr明显下降（P〈0．05）,肾组织匀浆ACE活性和MDA含量和肾小管损伤分数均明显增加（P〈0．01）,肾组织Sp1蛋白的表达明显上调（P〈0．05）;注射对比剂后24h尿NAG酶活性明显较注射前24h增高（P〈0．001）。12月龄鼠注射对比剂组与相应对照组比较,Scr明显上升（P〈0．05）,但升高幅度小于对照组的25％,肾组织匀浆MDA和ACE、肾小管损伤分数以及肾组织Sp1蛋白表达有上升趋势,但均无统计学意义（P〉0．05）。4月龄鼠注射对比剂组与相应对照组相比,上述各项指标比较均无统计学意义（P〉0．05）。结论增龄是雄性大鼠碘CI—AKI的促进因素,氧化性应激、ACE和核转录因子Sp1在老龄雄性大鼠碘CI-AKI发病机制中起一定作用。     

Aging and exercise affect the level of protein acetylation and SIRT1 activity in cerebellum of male rats

Aging is associated with a gradual decline in cognitive and motor functions, the result of complex biochemical processes including pre- and posttranslational modifications of proteins. Sirtuins are NAD⁺ dependent protein deacetylases. These enzymes modulate the aging process by lysine deacetylation, which alters the activity and stability of proteins. Exercise can increase mean life-span and improve quality of life. Data from our laboratories revealed that 4 weeks of treadmill running improves performance in the Morris Maze test for young (4 months, old) but not old (30 months, old) male rats, and the exercise could not prevent the age-associated loss in muscle strength assessed by a gripping test. The positive correlation between protein acetylation and the gripping test suggests that the age-dependent decrease in relative activity of SIRT1 in the cerebellum impairs motor function. Similarly to the acetylation level of total proteins, the acetylation of ά -tubulin is also increased with aging, while the effect of exercise training was not found to be significant. Moreover, the protein content of nicotinamide phosphoribosyltransferase, one of the key enzymes of NAD biosynthesis, decreased in the young exercise group. These data suggest that aging results in decreased specific activity of SIRT1 in cerebellum, which could lead to increased acetylation of protein residues, including ά-tubulin, that interfere with motor function.     

Caloric restriction affects liver microsomal monooxygenases differentially in aging male rats

Caloric restriction (CR) extends life span and retards the onset of physiological changes and pathologies associated with aging, but the underlying mechanisms remain unresolved. This study demonstrates that CR postpones the documented age-related declines in and/or enhances the activity and microsomal concentration of several liver monooxygenases in male rats, i.e., NADPH cytochrome P-450 reductase, total cytochromes P-450. However, the relative concentration of cytochrome P-450b+C did not exhibit statistically significant changes, whereas another isozyme, the male specific P-450h, declined significantly in both ad libitum-fed and CR rats as a function of increasing age. While CR appears to retard age-associated changes in certain liver enzymes, this effect is by no means universal. The hepatic monooxygenases constitute a well-characterized enzyme system in which to examine the perturbation of the aging process by CR.