首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
This study assesses the relation between age related macular degeneration (ARMD) and age, sex and occupation. It is designed as a retrospective study conducted on patients presenting to the Eye Polyclinic "Dr. L. Pavicevi?", Rijeka, Croatia, during the years 1995, 2000 and 2005, and included total of 6617 patients. The number of patients diagnosed with ARMD, their age and sex distribution, as well as the correlation between occupation type (indoor/outdoor) and the incidence of ARMD were analyzed. The results of our study show that the incidence of ARMD is slightly increased in female vs. male, strongly age related, as expected, and significantly increased in patients with outdoor type of occupation. Besides, an increasing trend of incidence is noted.  相似文献   

2.
3.
4.
5.
6.
1. Muscle biopsies were collected from 85 thoroughbred horses and analysed for carnosine content by an automated HPLC method. 2. No significant sex difference was found between colts, geldings and fillies. 3. There was a trend towards lower muscle carnosine contents with age, which was only significant between 1-year-old untrained horses and 4+ year-old horses (P less than 0.002).  相似文献   

7.
Energy storage in arthropods has important implications for survival and reproduction. The lipid content of 276 species of adult arthropods with wet mass in the range 0.2–6.13 g is determined to assess how lipid mass scales with body mass. The relative contribution of lipids to total body mass is investigated with respect to phylogeny, ontogeny and sex. The lipid content of adult insects, arachnids, and arthropods in general shows an isometric scaling relationship with respect to body mass (M) (Marthropod lipid = ?1.09 ×Mdry1.01 and Marthropod lipid = ?1.00 ×Mlean0.98). However, lipid allocation varies between arthropod taxa, as well as with sex and developmental stage within arthropod taxa. Female insects and arachnids generally have higher lipid contents than males, and larval holometabolous insects and juvenile arachnids have higher lipid contents than adults.  相似文献   

8.
Cigarette consumption during pregnancy produces deleterious effects in both, mother and fetus, some of them due to the presence of toxic elements in cigarette smoke, such as cadmium. Placenta constitutes a dual-purpose specimen for evaluating the pollutant burden exerted on the mother as well as on the fetus. The main objective of this study was to establish a correlation between placental concentration and distribution of some metal elements and birth weight of neonates delivered by mothers, who were either moderate smokers or nonsmokers. Forty nonsmoking and moderate smoking pregnant women paired per age, parity, weight, height and body mass index were selected. Smoking was assessed by self-reported cigarette consumption during pregnancy and urine cotinine concentration before delivery. Placental metal concentrations were evaluated by atomic absorption spectrometry (copper and cadmium) and neutron activation analysis (zinc and iron). Newborns from smokers had lower birth weights compared to infants from nonsmokers. Birth weights were correlated with placental cadmium concentrations in both, smokers and nonsmokers. Placental zinc and cadmium of smokers were mainly located at the maternal side and their levels were higher than those found in nonsmokers placentas. In addition, all metal nutrient/pollutant ratios were decreased in the smoker group. In this first study performed in our region, we found that moderate smoking mothers deliver neonates with decreased birth weight and highly correlated to placental cadmium concentration. Decreased metal nutrient/pollutant ratios, a condition here found in smokers, may indicate a placental dysfunction, contributing to impair birth weight.  相似文献   

9.
S Sen  G Talukder  A Sharma 《Cytobios》1985,42(166):87-91
Cytophotometric estimation of DNA values from human buccal mucosa and lymphocyte culture nuclei shows a difference related to different X chromosomal abnormalities, namely, del X, XO, XXX and XXY. The values in the buccal mucosa in all cases except XXX were similar to the normal XX and XY. In lymphocytes nuclei, however, a steady increase in the DNA content at a significant level could be related to an increase in the number of X chromosomes. The similarity in the DNA values of normal XX and XY controls may be attributed to asynchrony in the replication patterns of X and Y chromosomes.  相似文献   

10.
Whole body content of androgen (testosterone + 5 alpha-dihydrotestosterone) was invariably higher in male than in female rat pups killed 1 or 3 h after natural delivery, whereas androgen content was equivalent in males and females killed immediately or 6, 12, and 24 h after birth. Testicular content of androgen was significantly elevated in males killed 1 and 24 h after birth, compared with levels in males killed immediately, or 3, 6, and 12 h after birth. Thus, heightened testicular androgen content was only initially associated with increased systemic levels of androgen in males during the immediate postpartum period. A second study assessed the possibility that the body's clearance (i.e., metabolism plus excretion) of testosterone is lower in newborn rats upon separation from the placental circulation than in slightly older pups. Rats of both sexes killed 1 and 3 h after s.c. injection of [3H] testosterone had significantly higher plasma concentrations of [3H] testosterone as well as several 5 alpha-reduced androgens (5 alpha-dihydrotestosterone, 3 alpha-androstanediol, and androsterone) when injections were given within minutes as opposed to 24 h after birth. This suggests that in both sexes the clearance of testosterone is slower immediately after birth than at later ages. This phenomenon together with a brief postnatal elevation in the testicular synthesis and secretion of testosterone may explain the temporary rise in circulating androgen concentrations that occurs in the newborn male rat.  相似文献   

11.
12.
Intact trophozoites of the virulent Entamoeba histolytica strain HM-1:IMSS (HM-1) destroyed a monolayer of baby hamster kidney (BHK) cells at a higher rate and efficiency than trophozoites of the nonvirulent strain HK-9. The destructive effect could be partially attributed to the proteolytic activity of the amoeba, since quantitative differences were found in the enzymatic activity of the two strains tested. Crude extracts or secreted enzymes of HM-1 trophozoites digested Azocoll, as well as the bovine cold-insoluble globulin fraction, at a much higher rate than the corresponding preparations from HK-9. This proteolytic activity was found to be activated by free sulfhydryl groups. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the BHK cell proteins of pre- and postamoebic activities showed patterns similar to the trypsin effect on the same target cells. These enzymes were found to digest the proteins participating in the attachment of the target cells to the substrate and, consequently, cause detachment of these cells.  相似文献   

13.
Grass culms are known to differ in breaking strength, but there is little physicochemical data to explain the response. The fourth internode of four brittle and two nonbrittle barley (Hordeum vulgare L.) strains were used for physical and chemical studies of culm strength. Inner and outer culm diameters of brittle strains (3.6 ± 0.2 and 5.0 ± 0.1 millimeters) were not significantly different from those of nonbrittle strains (3.9 ± 0.2 and 5.2 ± 0.2 millimeters). Maximum bending stress, at which the culm was broken, was 192 ± 34 g/mm2 for brittle and 490 ± 38 g/mm2 for nonbrittle strains. Wall thickness and cell dimensions of epidermal, sclerenchyma, and parenchyma cells were measured in culm cross sections. The area of cell wall per unit cell area for each tissue was significantly correlated with the maximum bending stress (r = 0.93 for epidermis, 0.90 for sclerenchyma, and 0.84 for parenchyma). Cell walls of brittle culms had 6 to 64% as much cellulose content as those of nonbrittle culms. Maximum bending stress correlated significantly with cellulose content of the cell walls (r = 0.93), but not with the contents of noncellulosic compounds. The lower cellulose content of the brittle culm was significantly correlated with brittleness.  相似文献   

14.
Parental investment hypotheses regarding mate selection suggest that human males should seek partners featured by youth and high fertility. However, females should be more sensitive to resources that can be invested on themselves and their offspring. Previous studies indicate that economic status is indeed important in male attractiveness. However, no previous study has quantified and compared the impact of equivalent resources on male and female attractiveness. Annual salary is a direct way to evaluate economic status. Here, we combined images of male and female body shape with information on annual salary to elucidate the influence of economic status on the attractiveness ratings by opposite sex raters in American, Chinese and European populations. We found that ratings of attractiveness were around 1000 times more sensitive to salary for females rating males, compared to males rating females. These results indicate that higher economic status can offset lower physical attractiveness in men much more easily than in women. Neither raters' BMI nor age influenced this effect for females rating male attractiveness. This difference explains many features of human mating behavior and may pose a barrier for male engagement in low-consumption lifestyles.  相似文献   

15.
Compounds mutagenic toward Salmonella typhimurium strain TA98 in the presence of rat-liver homogenates (S9) were formed when fish flesh was fried at 199 degrees C. Three species of Hawaiian fish commonly consumed in Hawaii (skipjack tuna, Katsuwonus pelamis; yellowfin tuna, Neothunnus macropterus; and milkfish, Chanos chanos) were cooked in an electric skillet, along with samples of sole (Microstomus pacificus). Organic extracts of the fish were tested in the Ames Salmonella mutagenic assay using tester strain TA98 and S9. Basic organic extracts of fried, but not raw, samples exhibited significant mutagenicity. The levels of mutagenicity were also higher among the red flesh Hawaiian fish ('ahi, aku and awa) than with the white flesh sole. Creatine and creatinine contents were highest in the Hawaiian fish and lower in the sole. Creatine levels in the fish were 50-100 times greater than the creatinine content and varied from a high of 645 mg/100 g wet weight of fish for yellowfin tuna to a low value of 251 mg/100 g for sole. Mutagen levels are only approximately related to creatine/creatinine levels suggesting that other components contained in these fish may be as important as the guanidines in determining the levels of mutagen in the cooked fish.  相似文献   

16.
The lysosome content of lymphocytes has been analyzed with lysosomotropic vital stains and the fluorescence-activated cell sorter (FACS). Large granular lymphocytes (LGL), which account for virtually all natural killing activity in peripheral blood, are quantitatively different from small lymphocytes (SL) in this respect. LGL obtained by Percoll gradient density centrifugation accumulate more of the lysosomotropic vital dyes than SL do, staining with either neutral red or mepacrine (quinacrine). Furthermore among the LGL-rich, low density lymphocyte population highly, granulated cells can be separated from less granulated ones by mepacrine staining and FACS. Thus, separated highly granulated LGL express very high natural killing, whereas the less granulated low density large lymphocytes do not kill.  相似文献   

17.
Authors investigated some fiber and some hashish hemp sorts concerning their trichomes on the leaves. Histochemical reactions were developed using the Fast Blue Salt (FBB) reagent applied so far only thin layer chromatography. Glandular hairs were found giving positive reactions due to cannabinoids contained by the cells. The electron microscopic features were studied and the cannabinoid content was measured with GC. A correlation was found between the number of typical glandular hairs and cannabinoid content.  相似文献   

18.
Abstract Pheromone production in virgin females of Heliothis virescens (F.) (Lepidoptera: Noctuidae) peaked between the fourth and seventh hours of scotophase on the second, third, fourth and fifth days following eclosion. The highest peak (186 ng) occurred on day 3 after eclosion. Z-11-Hexadecenal comprised the highest proportion of seven components in the pheromone glands. Disproportionately higher amounts of hexadecanal and Z-11-hexadecenol occurred during photo-phase and other periods when low quantities of total pheromone were recorded.
Mating suppressed pheromone production which remained low until 48 h after mating. Coupling females with males mated three times previously or with 6-day-old males was less effective in causing a drop in pheromone content which peaked again 24 h after mating. This suggests the transfer of a male factor, a pheromonostatic factor, that suppresses pheromone production in mated females and that the factor from older and previously mated males is less effective.  相似文献   

19.
In order to assess whether intratesticular hormone content may be helpful for prediction of successful conception in men with fertility problems, five sex steroids, testosterone, dihydrotestosterone, androstenedione, estradiol and, for the first time epitestosterone, were measured in testicular tissue obtained by surgical retrieval from total 84 men. The group consisted of non-obstructive azoospermic men, aged 21-67 years who attended the centre for in vitro fertilization. Steroids after ether extraction and solvent partition were separated by high performance liquid chromatography and then measured by specific radioimmunoassays. The values varied considerably with means ± S.D. 2.43±2.47, 0.27±0.24, 0.080±0.13, 0.071±0.089 and 0.31±0.27 for testosterone, dihydrotestosterone, androstenedione, estradiol and epitestosterone, respectively.  相似文献   

20.
The great diversity of sex determination mechanisms in animals and plants ranges from genetic sex determination (GSD, e.g. mammals, birds, and most dioecious plants) to environmental sex determination (ESD, e.g. many reptiles) and includes a mixture of both, for example when an individual’s genetically determined sex is environmentally reversed during ontogeny (ESR, environmental sex reversal, e.g. many fish and amphibia). ESD and ESR can lead to widely varying and unstable population sex ratios. Populations exposed to conditions such as endocrine‐active substances or temperature shifts may decline over time due to skewed sex ratios, a scenario that may become increasingly relevant with greater anthropogenic interference on watercourses. Continuous exposure of populations to factors causing ESR could lead to the extinction of genetic sex factors and may render a population dependent on the environmental factors that induce the sex change. However, ESR also presents opportunities for population management, especially if the Y or W chromosome is not, or not severely, degenerated. This seems to be the case in many amphibians and fish. Population growth or decline in such species can potentially be controlled through the introduction of so‐called Trojan sex genes carriers, individuals that possess sex chromosomes or genes opposite from what their phenotype predicts. Here, we review the conditions for ESR, its prevalence in natural populations, the resulting physiological and reproductive consequences, and how these may become instrumental for population management.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号