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PubMed2004

[Levels of sex hormones in obese women with hypertension during various periods of reproductive activity].

AIM: To assess effects of hypertension and obesity on blood plasma levels of sex hormones and gonadotropins in fertile and postmenopausal women. MATERIAL: We assessed endocrinological status and measured levels of sex hormones and gonadotropins in 228 women with grade I-III hypertension (WHO, 1999) and 114 normotensive women of fertile and postmenopausal ages (17 to 74 years). There was a definite relationship between obesity and levels of sex hormones which did not depend on blood pressure level. The authors regarded this relationship as an endocrinological consequence of obesity. Severity of hypertension was associated with elevation of luteinizing and follicle-stimulating hormones and lowering of progesterone level in fertile women and with elevated levels of sex hormones in blood plasma in menopausal women. The authors interpreted the latter phenomenon as a sign of adrenal gland hyperfunction.

Adolescent↗
PubMed2000

Influence of host plant on growth and reproduction of Aphis nerii and feeding and prey utilization of its predator Menochilus sexmaculatus.

Influence of different physiological stages (young, mature and senescent) of Calotropis gigantea leaves on growth and reproductive ability of A. nerii and feeding, prey utilization, fecundity and lipid content of its predator M. sexmaculatus were investigated. Increased reproductive period, total life span and reproduction of nymphs per female of A. nerii were observed when reared on mature leaves. This relative preference of A. nerii and maximum utilization of mature leaves as compared to other physiological aged leaves are mainly due to changes in the chemical composition such as protein, carbohydrate, lipid, amino acid, nitrogen and phenolic of C. gigantea. Further, aphids reared on mature leaves influenced its predator's (M. sexmaculatus) growth, prey utilization and reproductive performances. Fecundity and longevity were high, while developmental time of predator was shorter on mature leaves fed aphid. Maximum prey utilization and increased efficiency of ingested and digested food of predator was observed on mature leaves reared aphid. The results are interpreted and discussed in relation to plant aphid and predator interaction (tritrophic).

Animals↗
PubMed1987

Aging can be genetically dissected into component processes using long-lived lines of Caenorhabditis elegans.

The aging process has been dissected by analysis of genetic variants of the nematode Caenorhabditis elegans. Long-lived recombinant inbred lines were generated; some of these lines have mean and maximum life spans up to 70% longer than wild type. Longer life results from a slowing of the characteristic exponential increase in mortality rate that is typical of aging populations in all species. The length of developmental periods and the length of the reproductive period are unrelated to increased life span. Lengthened life is due entirely to an increase in postreproductive life span. Development, reproduction, and life span are each under independent genetic control. General motor activity decays linearly with chronological age in all genotypes. The decay in general motor activity is correlated with and a predictor of life span, suggesting that both share at least one common rate-determining component.

Aging↗
PubMed2002

Annual variations and sex-related differences of estradiol-17beta levels in the anthozoan Renilla koellikeri.

In the sea pansy Renilla koellikeri, estradiol-17beta (E(2)) levels exhibited an annual pattern of secretion that correlated with the reproductive cycle, and displayed sex-specific and tissue-specific differences. The E(2) levels were low during the non-reproductive period extending from autumn to winter. A first rise of E(2) concentrations occurred in March when gonad maturation resumed, as indicated by an increase in lipid storage. This suggests that E(2) may influence the beginning of gonad maturation in the sea pansy. Estradiol-17beta returned to basal levels in April and May when lipids rose sharply. A second, more significant surge of E(2) levels occurred in June when spawning was initiated and it was more marked in female than in male colonies. This suggests that E(2) may participate in synchronising of oocyte maturation around spawning time to optimise the probability of fertilisation. The higher E(2) levels in somatic tissues (peduncle and polyps) than in eggs during the March peak revealed a non-reproductive origin for E(2) and the need for transport of E(2) through the gastrovascular cavity to reach reproductive tissues. Further analyses are required to determine the relative contribution of E(2) to reproductive events and its pathway of synthesis in this colonial anthozoan.

Animals↗
PubMed1992

The effect of nuptiality status variables on fertility: the Kenyan experience.

"This paper examines the relationship between fertility and nuptiality in Kenya using data from the Kenya Fertility Survey 1977/78. The results show that completed fertility (the cumulative fertility at the end of the reproductive period 15-49) decreases with the rise in age at first marriage. Type of union is also found to affect marital stability, frequency of marriage and consequently completed fertility. Regardless of type of union, women whose first union is still continuing have higher fertility than those women whose first union was dissolved and who married once or several times after. Highest fertility is experienced by women married only once and...in monogamous unions. The results also show that polygamously married older women among the rural populations experience higher fertility than their counterparts in the urban areas regardless of age." (SUMMARY IN AFR)

Africa↗
PubMed1991

Plasma prostaglandin F2 alpha in the male Triturus carnifex (Laur.) during the reproductive annual cycle and effects of exogenous prostaglandin on sex hormones.

Plasma patterns of prostaglandin F2 alpha (PGF2 alpha) and sex hormones (progesterone, androgens and 17 beta-estradiol) have been studied in the male crested newt, Triturus carnifex (Laur.), during the sexual cycle. The effects of exogenous PGF2 alpha on sex steroids have also been observed. In addition, effects of one week's captivity are reported. The patterns of plasma sex hormones, during the annual cycle, are consistent with the results previously reported for the same newt species. PGF2 alpha plasma level peaks in April, is low in summer, and progressively increases during autumn to peak again in December. The April PGF2 alpha peak coincides with a plasma estradiol increase and with an androgens drop. In April-collected newts, moreover, PGF2 alpha treatment induces a significant estradiol increase. These findings lead us to suppose that at the end of the breeding season (April) a PGF2 alpha-dependent estradiol synthesis occurs which could be implied in reproductive period termination. In several vertebrates, including some amphibian species, in fact, chronic administration of estradiol results in a strong inhibition of testicular endocrine tissue activity. The putative role of PGF2 alpha-dependent estradiol production in the gonadal regulation in amphibia living in temperate zones is discussed. The autumn PGF2 alpha increase has been tentatively related to the recovery gonadal processes and secondary sexual character development.

Androgens↗
PubMed1985

Communication and control in reproduction: the ubiquity of periodic phenomena.

Two statements will be presented and defended in this paper. First, it is claimed that oscillations are common in all biological systems. From the subcellular to the organismic levels of organization, oscillations are the normal operational mode for many biochemical and physiological control networks. Second, it will be demonstrated that periodic control offers several functional advantages over steady-state control.

Animals↗
PubMed1990

Changes in mallard (Anas platyrhynchos) serum chemistry due to age, sex, and reproductive condition.

Selected serum constituents were analyzed from 50 adult mallards (Anas platyrhynchos) of both sexes during several stages of reproduction: pre-egg laying, egg laying, incubating, molting, and postreproductive. Similar assays were conducted on sera from ducklings aged 5 to 58 days. Values for total protein (TPR), albumin (ALB), glucose (GLU), gamma-glutamyl transferase (GGT), calcium (CA), phosphorus (PHOS) and magnesium (MG) differed by sex. When all data were combined and analyzed for sex-related differences within each reproductive condition separately, all assays except lactate dehydrogenase (LD-L), cholinesterase (CHE), alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine (CRN) and direct bilirubin (BIDI) differed between sexes during one or more reproductive periods. Each assay showed differences among the various reproductive conditions regardless of gender. The pattern of change differed between sexes. All assays except ALB, GLU, CA and MG showed age-related changes. Lipemia in the sample interfered with all chemistries except TPR, LD-L and CA. Results indicate that when using clinical chemistry as a diagnostic tool in the mallard, age and reproductive condition should be determined in order to compare the data to appropriate control values.

Age Factors↗
PubMedDate not supplied

[Ecology of flea groups of the species conformis (Siphonaptera: Pulicidae: Xenopsylla) of the fauna of Russia and adjacent countries (review)].

Within the boundaries of the former USSR, the northern part of the conformis group distribution is located. It spreads over the arid regions of the Trans-Cacucasus, Pricaspijckaja lowland, Kazakhstan and Middle Asia. In this area 10 species and subspecies occur. They are mainly parasites of gerbillins. Unlike many other Siphonaptera the conformis fleas, when in the host's home, do not concentrate in the nest but inhabit the passages of burrow and food chambers throughout the year. On this reason the preimaginal development and existence of the adults take place not at the temperature of the habitable nest, which is heated by the host body, but at the temperature of the soil at a depth of burrow. The temperature threshold for preimaginal development of conformis fleas is reported to be 10-12 degrees. Temperature below the threshold is fatal for all immature instars. On the contrary the imago can survive at freezing temperature. The annual cycle of the conformis fleas is characterized by the presence of adults throughout the year. They breed in the warmer season and overwinter in the state of reproductive diapause. In this state the fleas are able to attack the host and to feed but do not deposit eggs. In the north deserts the reproduction begins at the early April and terminates at the early September. Southern, the reproductive period is longer. Furthermore, the complete interruption of the reproduction in the autumn-winter time may be absent as it was observed in X. gerbilli gerbilli and X. hirtipes in the south of the Middle Asia. On the other hand it is noted that in southern deserts the rate of oviposition falls in the most hot time. The number of generation per year in the conformis fleas varies from 2-3 in north deserts to 6-7 in south ones. The flea populations peak in late autumn when the insects cease to bread. The high abundance is maintained until springtime. After the diapause is ceased and the fleas begin breeding their abundance declines. In the late spring and early summer the emergence of adults begins and the populations increase. In a mild of summer the second fall takes place and then the fall is replaced by the autumnal peak. On their main hosts the conformis fleas prevail over all other species of Siphonaptera especially for warmer time when their quota among other fleas does not descend as a rule below 90% but more oftently it approaches to 100%. The fleas of this group and especially species parasitizing Rhombomys opimus are remarkable for the high level of their abundance. In the northern deserts in the periods of the most high abundance (late autumn, winter and early spring) the number of fleas per burrow occupied by family of Rh. opimus exceeds usually 1000 specimens and sometimes it can reach several thousands. In the southern deserts the abundance of the fleas is lower but the period of their active parasitizing is longer. In the species parasitizing Rh. opimus it is shown that in a complex burrow only some part of fleas has the possibility to feed regularly. In the spring and summer the percentage of fleas daily attacking the host varied from 17 to 86% and from 10 to 150 ectoparasites feed daily on one animal depending on the quantity of fleas and of hosts in the burrow. The number of attacking fleas is regulated by behaviour of the hosts, which change the used parts of burrow when the fleas are crowded there.

Animals↗
PubMed1998

[The morphofunctional characteristics of the testicular interstitial endocrinocytes in the red suslik (Citellus major Pallas) during a seasonal change in reproductive activity].

Light and electron microscopy, morphometric methods were used for studying Leydig cells of Citellus major Pallas from Orenburg Province populations in seasonal changing. Dynamics of structural changes in certain parameters of testis (area of interstitial tissue of the section, diameter of seminiferous tubules, endocrinocyte number, their nuclear volume, the state of structural components of the cytoplasm) in seasonal changing of the reproductive activity was shown. The highest functional activity of Leydig cells was noted during the reproduction period (the beginning of April) and before the onset of hibernation period. However, Leydig cells activity decreases insignificantly during the reproductive activity decline and it remains elevated during spring and summer.

Animals↗
PubMed1997

Bone mass and risk factors for bone loss in perimenopausal Danish women.

OBJECTIVES: To determine risk factors for low bone mass at menopause and risk factors for subsequent bone loss in the following period. DESIGN: A cross-sectional study and a 2-year prospective follow-up. SETTING: The catchment area of Sundby Hospital in Copenhagen. SUBJECTS: Four hundred and thirty-three women aged 45-58 years, with amenorrhea for 3-24 months, of whom 87 were followed for a 2-year period. MEASUREMENTS: Registration of life-style and anthropometric variables, reproductive history, and family history of fractures. Total body bone mineral content (BMC) was measured with dual energy X-ray absorptiometry. RESULTS: By means of multiple regression analysis height, body weight, and length of reproductive period were found to be positively related to whole body BMC (P < 0.001), whilst a negative relationship was found to age (P < 0.001), smoking (P < 0.001), and family history of fractures (P < 0.005). In the longitudinal study, only body weight at the inclusion (P = 0.005) and subsequent changes in body weight and fat mass (P < 0.001) were related to the changes in bone mass. CONCLUSION: The most significant predictors for bone loss were changes in body weight and fat mass. Hence, weight loss is a risk factor for bone loss in the early postmenopausal period, whereas weight gain seems to preserve bone.

Body Weight↗
PubMed1993

The reproductive effects of dietary heptachlor in mink (Mustela vison).

Adult female mink were fed diets containing 0 (control), 6.25, 12.5, and 25 ppm (micrograms/g) technical grade heptachlor prior to and throughout the reproductive period (181 days) to evaluate the effects of heptachlor consumption on reproduction and offspring viability and to assess the extent of placental and mammary transfer of heptachlor epoxide to mink offspring. Feeding 12.5 and 25 ppm resulted in significant reductions in feed consumption and body weights of female mink. Mortality was 0, 8, 67, and 100% for the control, 6.25, 12.5, and 25 ppm groups, respectively. All females in the 25 ppm group died within 88 days. Mink fed the two higher heptachlor diets displayed clinical signs indicative of central nervous system involvement just prior to death. Females were mated with males on the same dietary treatments. Whelping success rates were 67, 83, 27, and 0% for the control, 6.25, 12.5, and 25 ppm groups, respectively. High mortality in the 12.5 and 25 ppm groups accounted for the lack of reproductive success. Gestation length, litter size and birth weight of kits were not significantly affected by adult female consumption of 6.25 ppm heptachlor while kits helped by females on the 12.5 ppm diet weighed significantly less than control kits at birth. Survival of kits in the 12.5 ppm group from birth to three weeks of age was also adversely affected. At three and six weeks of age, kit body weights in both the 6.25 and 12.5 ppm groups were significantly less than body weights in control kits.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗