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PubMed2001

[Genetic explanation for vertical evolution].

The genetic theory of natural selection proposed by Fisher takes into account differential reproduction success of organisms, which may be estimated by using the Malthusian parameter as fitness. However, the minimum possible value of this parameter depends on ecological stability of an organism, which determines the probability of the survival and participation in reproduction for each viable offspring. In the course of vertical evolution, leading to an increase in the level of biological organization, ecological stability of organisms increases, and this might be accompanied by a decrease in their fitness. In the macroevolutionary process, alterations in ecological stability of organisms, including those responsible for an increase in the level of biological organization, are basic and primary changes whereas alterations in fitness are additional and secondary.

Adaptation, Physiological↗

PubMed1988

Effects of different food (Chlorella) concentrations on the chronic toxicity of cadmium to survivorship, growth and reproduction of Echinisca triserialis (Crustacea: Cladocera).

Extraneous factors have been shown to greatly modify pollutant stress. The present study was conducted with the objective of determining whether differences in food levels could modify chronic toxicity of cadmium to the various life-history parameters of the cladoceran Echinisca triserialis. Laboratory experiments were conducted on a sublethal range of cadmium (0, 2.5, 5.0, 10 and 20 microg litre(-1)) on life-history parameters such as survivorship, longevity, life expectancy, age at first reproduction, total fecundity, neonate size, net reproductive rate (R0), generation time (T), intrinsic rate of natural increase (r) and growth of Echinisca triserialis in relation to different food (Chlorella) levels of 0.5 (low), 1.5 (medium) and 4.5 (high) x 10(6) cells ml(-1). Cadmium levels of 10 microg litre(-1) and above, and low food levels, had a profound effect in decreasing the magnitude of all parameters studied. EC50 levels computed for life-history parameters, such as longevity, life expectancy at birth, total fecundity, R0 and T, were in the range of 2 to 21 microg litre(-1) cadmium, and this is indicative of extreme adverse effects on the population dynamics of E. triserialis when exposed to low food levels. At high food levels the EC50 was not achieved for cadmium in the toxicant range studied. The significance of these results is discussed in relation to field conditions.

Journal Article↗

PubMed1999

Toxicity of nickel to a soil-dwelling springtail, Folsomia fimetaria (Collembola: Isotomidae).

Exposure of the collembolan Folsomia fimetaria L. to nickel via soil caused significant mortality and reduced growth and reproductive output. Nickel may be present in elevated concentrations due to anthropogenic discharge. Although collembolans are very numerous and important organisms in the soil ecosystem, the effect of nickel has not previously been studied on these organisms. The aim of this study was to investigate the toxic effects of high soil nickel concentrations on the collembolan F. fimetaria following a 3-week exposure in a loamy sand spiked with nickel up to 1000 mg Ni/kg. A 10% decrease in adult female numbers at 427 mg Ni/kg and at 645 mg Ni/kg for adult male numbers was observed for nickel-spiked soil. Juvenile numbers were reduced at 701 mg Ni/kg following a 3-week exposure. The corresponding EC50 values were 786 mg Ni/kg for females, 922 mg Ni/kg for males, and 859 mg Ni/kg for juveniles. The reproductive output seems to be the most sensitive parameter being reduced at soil nickel concentrations above 173 mg Ni/kg (EC10). Adult growth was not affected by soil nickel concentrations up to 1000 mg Ni/kg, but juvenile growth was reduced at concentrations above 480 mg Ni/kg (EC10).

Animals↗

PubMed1989

Detection of the heme perturbations caused by the quaternary R----T transition in oxyhemoglobin trout IV by resonance Raman scattering.

The depolarization ratio dispersion and the respective excitation profiles of two structural sensitive Raman lines of oxyhemoglobin-trout IV (1,375 and 1,638 cm-1) have been measured at pH-values between 6.5 and 8.5. They were analyzed by employing a fifth order time dependent perturbation theory to calculate the polarizability tensor. This provides information about the pH-dependence of parameters reflecting symmetry classified distortions of the prosthetic heme groups. In order to correlate these distortions with functional properties of the molecule the following protocol has been employed: (a) a titration model was formulated relating each conformation of the molecule to a distinct set of distortion parameters the incoherent superposition of which provides the respective distortion parameter obtained from our Raman data. (b) The thermodynamic constants determining the equilibrium between these molecular conformations (i.e., the quaternary T and R-states, the low affinity t and the high affinity r-states of the distinct subunits, the pK-values of the Root- and Bohr groups) were obtained from a set of O2-binding curves that were analyzed in terms of an allosteric model suggested by Herzfeld and Stanley 1974. J. Mol. Biol. 82:231. The application of this procedure yields excellent reproduction of the pH-dependent effective distortion parameters of both Raman lines investigated. Thus established correlation between hemoglobin function (O2-binding) and structure (asymmetric perturbation of the hemegroup) provides some interesting insights into the molecular basis of the allosteric Root effect.

Animals↗

PubMed1997

Endotoxin inhibits the reproductive neuroendocrine axis while stimulating adrenal steroids: a simultaneous view from hypophyseal portal and peripheral blood.

This study was designed to test the hypothesis that systemic immune challenge with endotoxin inhibits the reproductive axis centrally by suppressing GnRH pulsatile release into hypophyseal portal blood. Using alert, normally behaving, ovariectomized ewes, we sampled hypophyseal portal blood at 10-min intervals beginning 4 h before and continuing 10 h after endotoxin (400 ng/kg, iv bolus, n = 6) or saline (vehicle, iv, n = 6). Simultaneous jugular samples for measurement of LH, cortisol, and progesterone were taken, and core body temperature was monitored by telemetry. Saline had no effect on any of the parameters in control ewes. In contrast, endotoxin dramatically inhibited the reproductive neuroendocrine axis coincident with stimulating the adrenal steroids, cortisol and progesterone, and elevating body temperature. Mean GnRH collection rate and GnRH pulse amplitude were suppressed (pre- vs. 7 h postendotoxin: collection rate 0.93 +/- 0.31 vs. 0.34 +/- 0.13 pg/min; amplitude 4.13 +/- 1.33 vs. 1.30 +/- 0.41 pg/min per pulse; P < 0.05 and P = 0.01). However, endotoxin did not have a significant effect on GnRH pulse frequency. Along with inhibited GnRH secretion, endotoxin significantly suppressed mean LH concentrations (P = 0.001) and LH pulse amplitude (P < 0.05). In addition, endotoxin suppressed LH pulse frequency (P = 0.01). Coincident with reproductive inhibition, endotoxin stimulated cortisol (P < 0.001), progesterone (P < 0.01), and core body temperature (P < 0.001). We conclude that the suppressive effects of endotoxin on the reproductive axis can be mediated centrally through an inhibition of GnRH and thus LH pulsatile secretion. The coincident stimulation of cortisol, progesterone, and temperature raises the possibility that the central inhibition of the reproductive system may be a consequence of any or all of these activated parameters.

Animals↗

PubMed2002

Influence of high levels of vitamin E on semen parameters of cocks.

This study was an attempt to find whether the reproductive performance of cocks would be influenced by oral administration of different amounts of dietary vitamin E over a long period of time. For that purpose 60 cocks were divided into five dietary groups of 12 animals each, and supplemented with 0 (control group), 100, 1,000, 10,000 or 20,000 IU alpha-tocopherol/kg diet, respectively, over a period of 12 months. The effect on semen parameters and biochemical parameters measured in pooled semen samples and the weight of the testes were determined. The weight of testes decreased with increasing amounts of supplemented vitamin E. Volume, pH, colour, consistency and motility were not influenced by the diets, but density of ejaculate (sperm/microl), total amount of spermatozoa and morphology of sperm were significantly lowered by increasing amounts of supplemented vitamin E. The alpha-tocopherol concentration in ejaculates increased significantly in relation to the diet whereas phospholipid content and thiobarbituric acid-reactive substances (TBARS) of the semen samples decreased significantly with increasing vitamin E supplementation. The reproductive performance of cocks was negatively influenced by high doses of vitamin E although decreased TBARS indicated rising oxidative defence.

Administration, Oral↗

PubMed1989

[Age-related changes in the indicators of immunological homeostasis in women with intact menstrual rhythm].

Immune status was evaluated with respect to reproductive capacity in 57 apparently normal female volunteers, aged 27 to 50 years, with intact menstrual pattern. The most valuable immune parameters, and major patterns of their change throughout the cycle, such as periovulatory immunosuppression, were identified for women of reproductive age. Correlations between immune and endocrine parameters as well as age-related changes thereof are discussed.

Adult↗

PubMed2006

Beneficial effect of microsurgical varicocelectomy is superior for men with bilateral versus unilateral repair.

PURPOSE: Varicocele represents the most common correctable cause of male infertility, and most reports indicate that varicocelectomy has a beneficial effect on male fertility and pregnancy outcome. Little is known about the differential effect of bilateral, compared to unilateral varicocelectomy, on male fertility potential. MATERIALS AND METHODS: A total of 369 consecutive varicocelectomies were performed for male factor infertility between July 1996 and July 2002. The outcomes measured include postoperative changes in semen parameters, pregnancy rates (assisted and unassisted) and use of assisted reproductive technology (intrauterine insemination and in vitro fertilization with intracytoplasmic sperm injection). RESULTS: There were 157 men who underwent bilateral and 212 who underwent unilateral left varicocelectomy. Both groups had comparable male and female ages, and baseline semen parameters. Semen parameters improved significantly after surgery in the bilateral and unilateral groups. Moreover, the improvement in percent motility was significantly greater in the bilateral compared to the unilateral group (8.0% +/- 1.7% compared to 4.4% +/- 1.5% improvement, respectively, p <0.01). In addition, the spontaneous pregnancy rate was significantly higher in the bilateral compared to the unilateral group (49% vs 36%, respectively, p <0.05). Assisted reproductive technology was comparable in the unilateral and bilateral groups (64% vs 51%, respectively, p >0.05). CONCLUSIONS: Our data indicate that bilateral varicocelectomy (for clinically palpable bilateral varicoceles) is associated with a significantly greater improvement in sperm quality (motility) and male fertility potential than unilateral varicocelectomy. The greater improvement in semen parameters and pregnancy outcome associated with bilateral varicocelectomy support the concept of a detrimental dose-effect of varicocele on male fertility potential.

Adult↗

PubMedDate not supplied

Pregnancy dating in the rat: placental morphology and maternal blood parameters.

The rat is commonly used as a model in studies on embryology and reproduction toxicology. Surprisingly, the current literature does not provide a comprehensive reference data set on placental development in rat. Therefore, we have evaluated morphological changes of the placenta and maternal blood parameters during pregnancy of the Sprague-Dawley rat. The morphologic data presented in this study may be useful as reference material. This study revealed that placental development in the rat is a well-defined process, characterized by key synchronized morphological events at specific points in time, convenient for laboratory practice and provides the toxicologist with a sensitive tool to distinguish between normal and abnormal placental development and to detect fetal and placental mismatches. During rat pregnancy, significant changes were observed in maternal blood parameters strongly reminiscent of those observed in pregnant women. These changes included: (a) decreased blood cell volume as a result of hemodilution, (b) increased white blood cell counts reflecting the response of the mother to the fetal allograft, (c) increased blood clotting values, (d) decreased plasma glucose and increased lipid content maximizing fetal glucose availability and maternal energy conservation, and (e) decreased electrolyte values reflecting plasma volume expansion. It was concluded that the combined data set on placental morphology and maternal blood parameters in pregnant rats provides powerful tools for recognition of abnormal pregnancies.

Animals↗

PubMed2005

Changes in semen quality and morphology of the reproductive tract of the male tammar wallaby parallel seasonal breeding activity in the female.

Changes in semen quality and morphology of the male reproductive tract were studied throughout the year in the highly promiscuous tammar wallaby. Body size, semen quality and gross morphology of the reproductive organs were assessed in adult males each month from January to November. The mean weight of males was similar in most periods sampled, but males were slightly heavier in the minor (P < 0.05) than the non-breeding season. Since body weight was correlated with weights of the testes, epididymides and accessory sex glands, organ weights were adjusted for body weight in subsequent analyses. In the major breeding season (late January/early February), when most females go through a brief, highly synchronized oestrus, the testes, prostate, Cowper's glands, crus penis and urethral bulb were heaviest, volume and coagulation of ejaculates were greatest, and sperm motility had increased. Semen samples collected by electroejaculation at this time contained low numbers of spermatozoa, possibly as a result of dilution and entrapment by the seminal coagulum or depletion of epididymal stores during intense multiple mating activity. In the non-breeding season (late May-July), when mating does not normally occur in the wild, there was a significant decrease in the relative weight of nearly all male reproductive organs and a decline in most semen parameters. In the minor breeding season (September-November), when pubertal females undergo their first oestrus and mating, the weights of testes, epididymides and most accessory sex glands had significantly increased similar to those of males in the major breeding season. The total number and motility of ejaculated spermatozoa were highest during this period, but the volume and coagulation of ejaculates and weight of the prostate had only increased to levels that were intermediate between the major and non-breeding seasons. Ejaculate volume was strongly correlated with prostate weight, and % motile spermatozoa was strongly correlated with epididymis weight. Semen quality thus varied seasonally with changes in androgen-dependent reproductive organs in the male tammar wallaby and appeared to be influenced by the seasonal timing of oestrus in females. Semen quality may also improve in response to an increase in the number of available oestrous females.

Animals↗

PubMed1976

Productive and reproductive adaptations of Friesian cattle introduced to a suptropical environment.

Various parameters were studied in imported and in local female cattle under the conditions in Iraq. The following results were obtained: The age at the first calving was lower in the animals imported in 1964 and 1965 than in the locally born cows. The age at the first calving in the daughter cows of the imported animals increased significantly by 1.6 months per year. The calving interval and the duration of the post-partum periods were longer in imported dams than in daughter cows. The gestation period was shorter in the imported dams than in the daughter cows. The lactation length and the dry period were longer in the imported dams than in their locally born daughters. The percentage of calves born during the life of all recorded cows in the studied herd was higher in the imported dams.

Adaptation, Physiological↗

PubMedDate not supplied

[Theoretical approaches to the evaluation of antiviral drug effectiveness].

It is suggested that (a) LD50 is the measure of the efficacy of antiviral drugs: (b) a disease is characterized by the "barrier" type of a pathological process when in pathogenesis there exists an event whose manifestation largely determines the outcome of a disease (recovery/severe form with a fatal outcome). If the event consists in the penetration of a pathogen into a susceptible cell and the consequent reproduction of an antigen, the value LD50 for man is expressed as the same parameter for a model animal and as the parameters determined by in vitro human and animal cell experiments. The parameters include the degree of viral production adsorption on the cell and the levels of its reproduction. The algorithms for evaluating the efficacy of viral drugs are based on the relationship. The adequacy of the relationship is illustrated by experimental findings.

Absorption↗

PubMed2005

Ameliorating effect of folic acid on chromium(VI)-induced changes in reproductive performance and seminal plasma biochemistry in male rabbits.

Chromium hexavalent (Cr(VI)) is a biologically active oxidized state of chromium. It is involved in the redox cycle, with the production of reactive oxygen species. Free radical scavenging properties and possible antioxidant activity of folic acid (FA) have been reported; therefore, the present study examined possible protective effects of FA on the reproductive toxicity of potassium dichromate (K2Cr2O7) in male New Zealand white rabbits. We monitored reproductive performance, lipid peroxidation, enzyme activities and biochemical parameters in seminal plasma. Six rabbits per treatment group (and a control group) were exposed: 8.3 microg/kg FA; 5 mg/kg potassium dichromate (contains 3.6 mg chromium(VI)) and 5 mg/kg potassium dichromate+8.3 microg/kg FA. Results showed that semen quality deteriorated following potassium dichromate exposure. Testosterone levels, body weight (BW), relative weights of testes (RTW) and epididymis (REW) all decreased. Levels of thiobarbituric acid-reactive substances increased, whereas the activities of glutathione S-transferase, transaminases and phosphatases decreased in the seminal plasma. FA alone significantly increased BW, RTW, REW, semen characteristics and seminal plasma enzymes, and decreased the levels of free radicals. Furthermore, FA can be effective in the protection of chromium-induced reproductive toxicity.

Acid Phosphatase↗

PubMed2006

Diagnosis of the compromised equine pregnancy.

Identification of a compromised pregnancy in the mare requires the exhaustive collection of a database that includes past and recent reproductive and medical histories and a variety of parameters indicating fetal distress and possibly suggesting neonatal compromise.Judicious interpretation of findings and serial recording of data throughout gestation may help in the early detection of abnormal fetomaternal exchange pathways. Some sources of compromise may be identified, and the impact on fetomaternal well-being maybe calculated. Appropriate preventive or corrective measures may then be implemented to minimize the risks of an unfavorable outcome.

Animals↗

PubMed2000

Enthalpic and entropic contributions to the conformational free energies of methylthio, methylsulfinyl, methylsulfonyl, phenylthio, phenylsulfinyl, and phenylsulfonyl

A variable-temperature NMR study of (cis-4-methylcyclohexyl)methyl sulfide (1), sulfoxide (2), and sulfone (3), as well as (cis-4-methylcyclohexyl)phenyl sulfide (4), sulfoxide (5), and sulfone (6) allowed determination of the thermodynamic parameters, DeltaH degrees and DeltaS degrees, for the title groups. Reproduction of the experimental results with Allinger's MM3 program was successfully accomplished in the case of the sulfoxide and sulfide groups. Nevertheless, modification of the original force field torsional parameters was required in order to adequately reproduce the experimentally observed behavior of the sulfonyl derivatives. Rationalization of the enthalpic and entropic contributions to DeltaG degrees [S(O)(n)()R, n = 0, 1, 2; R = CH(3), Ph] is advanced in terms of the steric characteristics of these sulfur-containing groups and the resulting rotameric populations in the axial and equatorial monosubstituted cyclohexanes.

Journal Article↗

PubMed2003

Pineal control of immune status and hematological changes in blood and bone marrow of male squirrels (Funambulus pennanti) during their reproductively active phase.

In addition to pineal control of reproduction in seasonal breeders, melatonin is also known to influence various immune parameters. In the present experiment, we assessed the effect of exogenous melatonin treatment on different hematological parameters of peripheral blood and bone marrow cells, together with histological observations of spleen and thymus blastogenic response and stimulation ratio, and hormonal assays (melatonin and testosterone) of Indian palm squirrel (Funambulus pennanti) during their reproductively active phase when endogenous melatonin levels are low. Daily subcutaneous injection of melatonin (25 microg/100 g body mass.) at 17.30-18.00 h to adult male squirrels for 60 consecutive days during May-June significantly increased the lymphocyte count of blood and bone marrow and the blastogenic response/percent stimulation ratio of spleen and thymus. Histological observation showed densely packed thymocytes and splenocytes. During this period, peripheral testosterone level was high and melatonin was low establishing an inverse relationship as noted earlier for this squirrel. In pinealectomized squirrels, decreased total leukocyte count and percent lymphocyte count in peripheral blood and bone marrow, along with a decreased cell density in spleen and thymus was observed histologically. Further, melatonin treatment of pinealectomized squirrels resulted in restoration of the immune parameters in line with a normal control level. We suggest that during the reproductively active period of male Indian palm squirrels the lymphoid organs were sensitive to melatonin; hence, the exogenous melatonin treatment had an immuno-enhancing effect.

Animals↗

PubMed2004

Effects of long-term use Topiramate on fertility and growth parameter in adult male rats.

PURPOSE: A case control study was conducted to assess the effects of long-term ingestion of Topiramate on fertility, body and reproductive organ weight and level of sex hormones in Sprague-Dawley male rats. METHODS: Ten adult male rats were exposed to Topiramate diets at a concentration of 100 mg /kg for 60 days. Another ten control male rats received vehicle (distilled water). After 24 hours of the last dose, animals were autopsied under light anesthesia. Several parameters including, body and reproductive organ weight, sperm count and motility, serum testosterone, FSH, levels of cholesterol, triglyceride, SGOT and SGPT were all measured. Assessment of pregnancies in females mixed with tested males was also measured. The results of histological, histometrical and biochemical profiles were compared to that of the control group, and the significance of these results was measured using student's ''t'' and Chi- square tests. RESULTS: Long-term ingestion of Topiramate for 60 days caused a significant decrease in spermatogenesis in seminiferous tubules of the testes. Sperm motility and density were also significantly reduced in cauda epididymides and testes of the treated group. The body weights and weight of reproductive organs (testes, epididymides, ventral prostate and seminal vesicle) were decreased considerably. Hormonal assay also showed significant decrease in testosterone levels. Testicular cell population dynamics also demonstrated a decrease in the number of both primary and secondary spermatocytes and spermatids in the treatment group. The number of female rats impregnated by male rats on long-term Topiramate diet had decreased. The number of implantations and the number of viable fetuses were also notably decreased in female rats impregnated by male rats ingested Topiramate. Histometry of reproductive organs confirmed these results. CONCLUSION: these results confirm that the long-term Topiramate ingestion produces adverse effects on fertility and reproductive system in adult male rat.

Administration, Oral↗

PubMedDate not supplied

Correlation of sperm parameters with apoptosis assessed by dual fluorescence DNA integrity assay.

Failed fertilization after intracytoplasmic sperm injection or miscarriages occurs in cases involving apoptotic and necrotic sperm. Identifying normal sperm is important for successful assisted reproductive technologies (ART) procedures. The study was conducted to correlate sperm parameters with intact sperm with normal DNA assessed by the dual stain assay in 118 separate individuals. The results showed differences in percent DNA intact sperm in individuals with normal W.H.O. sperm features (62 +/- 1.1; mean +/- S.E.M.) compared with oligoasthenoteratozoospermia patients (38 +/- 5.3). Individuals whose sperm had fertilizing capacity had higher percentages of intact DNA (60 +/- 1.3 versus 47 +/- 2.4). The percentages of intact DNA sperm were significantly correlated to total motility in semen (R = 0.7), post-wash motility (R = 0.6), rapid progression (R = 0.6), intact acrosome (R = 0.5), and strict morphology (R = 0.5). There were no correlations with the remaining parameters. The dual stain assay identified sperm with normal physiology and fertilizing capacity. The dual stain assay measures DNA integrity and is a promising method to select normal sperm for ART.

DNA↗