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PubMed2006

A chronic bioassay with the estuarine amphipod Corophium volutator: test method description and confounding factors.

Methods of conducting a chronic sediment toxicity test with the estuarine amphipod Corophium volutator are described. They consist of a 49-day exposure, after which mortality, growth and reproduction are determined. Pilot experiments were used to optimize test design parameters such as temperature, duration, feeding and refreshing regimes, and effects of indigenous organisms. By way of further validation, the present study focused on the effects of four different parameters: oxygen saturation, salinity, ammonium and nitrite. These confounding factors might play an important role especially if the test is used for risk assessment of field-contaminated sediments. It is concluded that the present experimental design is well suited for chronic sediment exposures with C. volutator. The test can be performed at a broad range of salinity values, provided that controls are performed at the same salinity. Results further demonstrate that with the endpoints growth and reproduction this chronic test procedure is a factor 7-18 more sensitive to ammonium and nitrate than the standardized acute bioassay (endpoint mortality).

Amphipoda↗

PubMed2003

The relationship between human semen parameters and environmental exposure to polychlorinated biphenyls and p,p'-DDE.

Scientific and public concern exists about potential reproductive health effects of persistent chlorinated organic chemicals, such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), and dichlorodiphenyldichloroethylene (DDE, the most stable daughter compound of DDT). To explore the hypothesis that environmental exposures to PCBs and DDE are associated with altered semen parameters, we conducted a cross-sectional study of 212 male partners of subfertile couples who presented to the Massachusetts General Hospital Andrology Laboratory. Semen parameters were analyzed as both a continuous measure and dichotomized based on World Health Organization reference values for sperm concentration (< 20 million/mL), motility (< 50% motile), and Kruger strict criteria for morphology (< 4% normal). The comparison group for the dichotomized analysis was men with all three semen parameters above the reference values. In serum, 57 PCB congeners and p,p -DDE were measured by congener-specific analysis using gas chromatography with electron capture detection. There were dose-response relationships among PCB-138 and sperm motility (odds ratio per tertile, adjusted for age, abstinence, and smoking, and p-value for trend were, respectively, 1.00, 1.68, 2.35, and p-value = 0.03) and morphology (1.00, 1.36, 2.53, p-value = 0.04). There was limited evidence of an inverse relationship between sum of PCBs, as well as those PCBs classified as cytochrome P450 enzyme inducers, with sperm motility and sperm morphology, as well as limited evidence of an inverse association between p,p -DDE and sperm motility. The lack of a consistent relationship among semen parameters and other individual PCB congeners and groupings of congeners may indicate a difference in spermatotoxicity between congeners.

Adult↗

PubMed2006

Relations between social status and the gonadotrophin-releasing hormone system in females of two cooperatively breeding species of African mole-rats, Cryptomys hottentotus hottentotus and Cryptomys hottentotus pretoriae: neuroanatomical and neuroendocrinological studies.

In common (Cryptomys hottentotus hottentotus) and highveld (Cryptomys hottentotus pretoriae) mole-rats, reproduction is subject to two forms of regulation in addition to incest avoidance. These are the only social bathyergids known to restrict breeding to a particular season; furthermore, subordinate members of their colonies show suppressed reproduction throughout the year. Females from both species were assessed and compared for social and seasonal effects on the gonadotrophin-releasing hormone (GnRH) system. GnRH-immunoreactive (ir) structures were visualized immunohistochemically; GnRH content was determined by radioimmunoassay. In both species, GnRH-ir cell bodies and processes are loosely distributed along the septopreopticoinfundibular continuum, with dense fiber aggregations in the region of the organum vasculosum of the lamina terminalis and median eminence. The two species differ in the rostrocaudal distribution of their GnRH-ir cell bodies. In highveld mole-rats, most of these cells are in the septal/preoptic area; in common mole-rats, more than half of them are in the mediobasal hypothalamus. Compared with common mole-rats, highveld mole-rats have a greater total number of GnRH-ir cell bodies, higher GnRH content, and more intense GnRH immunoreactivity in the median eminence. Within highveld colonies, the nonreproductive females have larger GnRH-ir cell bodies, more intense GnRH immunoreactivity in the median eminence, and higher GnRH content than the reproductive females; these findings suggest inhibited release of GnRH in the nonreproductive, subordinate females. In contrast, in common mole-rat females, neither status nor season appears to affect the investigated parameters of the GnRH system; this suggests a predominantly behavioral basis to their suppressed reproduction.

Animals↗

PubMed2004

Environmental color affects Nile tilapia reproduction.

We investigated the effects of environmental color on the reproductive behavior of Nile tilapia, Oreochromis niloticus. Two environmental colors were tested by covering the aquarium (60 x 60 x 40 cm) with white (12 groups) or blue (13 groups) cellophane and observing reproductive behavior in groups of 2 males (10.27 +/- 0.45 cm) and 3 females (10.78 +/- 0.45 cm) each. After assignment to the respective environmental color (similar luminosity = 100 to 120 Lux), the animals were observed until reproduction (identified by eggs in the female's mouth) or up to 10 days after the first nest building. Photoperiod was from 6:00 h to 18:00 h every day. Food was offered in excess once a day and water quality was similar among aquaria. Daily observations were made at 8:00, 11:00, 14:00 and 17:00 h regarding: a) latency to the first nest, b) number of nests, c) gravel weight removed (the male excavates the nest in the bottom of the aquarium), d) nest area, and e) mouthbrooding incubation (indication of reproduction). The proportion of reproducing fish was significantly higher (6 of 13) in the group exposed to the blue color compared the group exposed to the white color (1 of 12; Goodman's test of proportions). Moreover, males under blue light removed significantly larger masses of gravel (blue = 310.70 +/- 343.50 g > white = 130.38 +/- 102.70 g; P = 0.01) and constructed wider nests (blue = 207.93 +/- 207.80 cm(2) > white = 97.68 +/- 70.64 cm(2); P = 0.03) than the control (white). The other parameters did not differ significantly between light conditions. We concluded that reproduction in the presence of blue light was more frequent and intense than in the presence of white light.

Animals↗

PubMed2006

[Effect of high volume hemofiltration on pulmonary surfactant protein in endotoxin induced acute lung injury in dog].

OBJECTIVE: To explore the effect of high volume hemofiltration (HVHF) on pulmonary surfactant protein (SP) in endotoxin induced acute lung injury (ALI) in dogs. METHODS: Sixteen healthy male mongrel dogs were given lipopolysaccharide(LPS 650 mug/kg) via central vein within 30 minutes. After the reproduction of the model, they were divided into two groups randomly (n=8). One group received the treatment of HVHF and mechanical ventilation (MV, treatment group), while another received only MV (model group). Parameters of arterial blood gas and respiratory mechanics were recorded at basic values, after reproduction of the experimental model, and 1, 2 and 4 hours after HVHF. Content of SP-B in lung tissue homogenate was measured by protein Western blot. RESULTS: After injection of LPS, partial pressure of oxygen in artery (PaO(2)) and PaO(2)/fractional concentration of inspired oxygen (FiO(2)) began to decrease (both P<0.05). PaO(2)/FiO(2) <300 mm Hg (1 mm Hg=0.133 kPa) when ALI was reproduced. PaO(2) and PaO(2)/FiO(2) were higher in treatment group than those in model group 4 hours after HVHF (both P<0.01). Inspiratory resistance of airway (Raw) and peak inspiratory pressure (PIP) in model group were kept stable after MV. Lung dynamic compliance (Cdyn) and lung total compliance (Ctot) in model group were both decreased while ventilatory work of breathing (WOBvent) increased 4 hours after MV (all P<0.01). All parameters in the treatment group were kept stable and differences in Cdyn and Ctot were significant at 4 hours after HVHF compared to model group (P<0.01 and P<0.05). Content of SP-B in lung tissue homogenate was significantly higher in treatment group than that in model group (P<0.01). CONCLUSION: HVHF could effectively increase the content of SP-B in lung to prevent aggravation of respiratory mechanics and improve oxygenation.

Acute Lung Injury↗

PubMed1992

A model of the transmission of dengue fever with an evaluation of the impact of ultra-low volume (ULV) insecticide applications on dengue epidemics.

We have developed a deterministic susceptible, exposed, infectious, resistant or removed (SEIR) model of dengue fever transmission that enables us to explore the behavior of an epidemic, and to experiment with vector control practices. Populations of both host and vector are divided into compartments representing disease status (susceptible, exposed, infectious, and, for humans, resistant), and the flow between compartments is described by differential equations. Examination of the equilibrium points leads to a formulation of the basic reproduction rate (Z0) of the disease. With a base set of parameters, Z0 = 1.9 and the model realistically reproduces epidemic transmission in an immunologically naive population. Control of adult mosquitoes by ultra-low volume (ULV) aerosols is simulated by an abrupt decrease in vector densities, followed by gradual recovery of the vector population. The model indicates that ULV has little impact on disease incidence, even when multiple applications are made, although the peak of the epidemic may be delayed. Decreasing the carrying capacity of the environment for mosquitoes, and thus the basic reproduction rate of the disease, by source reduction or other means, is more effective in reducing transmission.

Animals↗

PubMed1977

Reproduction of twelve routinely used ECG leads from three orthogonal ones.

The paper presents the results of the reproduction of routinely used leads from three corrected orthogonal leads in the system SVEC III modified by L. I. Titomir. Simultaneously with routine and reproduced leads, the differences among them were recorded at every instant of time. In the reproduction for each proband and each lead an individual selection of vector parameters for the given lead was performed. This method was applied in the examination of 150 probands, including 121 patients with myocardial infarction (MI) and 29 healthy subjects. A comparison of routine with reproduced leads showed that in both healthy subjects and patients with MI the limb leads were well reproducible; reproduction of thoracic leads was poorer, especially in patients with MI. Greatest reproduction errors occurred in leads V2 and V3. In 12.5% of patients with anterior-wall infarct, the diagnostically highly important indicators, pathological Q and informative T waves, were not reproduced. The authors assume that in isolated anterior-wall MI, which manifests itself solely in leads V2 and V3, diagnostic errors occur when only three corrected orthogonal leads are used.

Aged↗

PubMed1990

Reproduction in the space environment: Part II. Concerns for human reproduction.

Long-duration space flight and eventual colonization of our solar system will require successful control of reproductive function and a thorough understanding of factors unique to space flight and their impact on gynecologic and obstetric parameters. Part II of this paper examines the specific environmental factors associated with space flight and the implications for human reproduction. Space environmental hazards discussed include radiation, alteration in atmospheric pressure and breathing gas partial pressures, prolonged toxicological exposure, and microgravity. The effects of countermeasures necessary to reduce cardiovascular deconditioning, calcium loss, muscle wasting, and neurovestibular problems are also considered. In addition, the impact of microgravity on male fertility and gamete quality is explored. Due to current constraints, human pregnancy is now contraindicated for space flight. However, a program to explore effective countermeasures to current constraints and develop the required health care delivery capability for extended-duration space flight is suggested. A program of Earth- and space-based research to provide further answers to reproductive questions is suggested.

Extraterrestrial Environment↗

PubMedDate not supplied

[Scientific evidence in occupational medicine: meta-analysis of the data regarding the effects of working with video terminals on the psycho-physical well-being].

Psycho-physical well-being of video display terminal (VDT) workers is often neglected. The aim of this study is to evaluate, through the comparison of controlled studies published in scientific literature, the psycho-physical well-being of VDT workers and, in particular way, the phenomena of strain and mental fatigue with their neuro-physiological, behavioural and subjective components. Seven-hundreds articles have been found from which we have selected twenty-one articles on the basis of the following inclusion criteria: controlled studies and evaluation of variables about mental fatigue; finally, only fifteen articles were utilized in the analysis due to the variability of data needed in the computation of effect size. For continuous variables we have performed two different types of elaboration methods; in case of variables showing no significant heterogeneity among studies, we have used the Weighted Mean Difference method, according to the Fixed Effect Model, while for variables showing significant heterogeneity among studies, we have used the Standardized Mean Difference method according to the Random Effects Model. Categorical variables have been analyzed trough the calculation of Odds Ratio according to the Fixed Effect Model or to the Random Effects Model respectively in case of heterogeneity's absence or presence among studies. Variables obtained by the studies were classified in four groups: biological assessment, strain assessment, subjective well-being assessment, and psycho-somatic symptoms. Statistically significant outcomes have been found for urinary adrenalin, sleep disturbances and for all the evaluated categorical parameters except headache. These outcomes allow for the following observations: 1) psycho-physical well-being of VDT workers, and especially mental fatigue, remain an object of uncertain identification and they are often neglected by Occupational Health doctors even though their evaluation is required by the Italian legislation (D.Lgs 626/94); 2) even though there is a huge interest on the argument, the amount of controlled studies on VDT workers is still insufficient. Furthermore, studies are often weak in power heterogeneous and discordant on potential problematic issues and consequently there is a difficulty in both the reproduction and overlapping of the studies; 3) Occupational Health doctor should be more careful toward this specific argument and, in his clinical practice, he should use only evidence-based parameters with high level of reproduction suggested by studied which can be considered homogeneous and overlapping for case studies and control groups. This meta-analysis suggests which evaluations to use as statistically significant parameters for the health protection of VDT workers.

Anxiety↗

PubMed2003

A clinical study comparing PureSperm and SpermFilter for density gradient separation of human spermatozoa in assisted reproduction.

OBJECTIVE: To compare a new density gradient medium, SpermFilter, for purifying spermatozoa in assisted reproduction with the more established medium, PureSperm. DESIGN: Part 1, a multicenter study on 225 semen samples purified using either PureSperm (115 semen samples) or SpermFilter (110 semen samples). Part 2, a retrospective, single center study on a total of 898 assisted reproductive cycles (245 insemination cycles using husband semen, 58 insemination cycles using donor semen and 595 in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles. SETTING: Part 1, three fertility clinics in Denmark (two university-affiliated fertility clinics and one private clinic). Part 2, one university-affiliated fertility clinic in Denmark. MAIN OUTCOME PARAMETERS: Part 1, purity of purified spermatozoa (% motile), motility index and recovery of motile spermatozoa. Part 2, malformation and baby take-home rates (insemination cycles), fertilization, cleavage, implantation, malformation and baby take-home rates (IVF/ICSI cycles). RESULTS: No statistical differences were observed in any of the parameters investigated. CONCLUSION: SpermFilter is a valid alternative to PureSperm in assisted reproduction technology (ART).

Adult↗

PubMed2001

Photographic reproduction of out-of-focus and distorted ocular imagery.

The necessary settings and parameters were determined for ordinary camera and lens systems to faithfully reproduce out-of-focus and distorted imagery as it falls upon the retina of the human eye. Theoretic considerations of both geometric and physical optics were used to calculate the "relative blur" and distortion produced by refractive error added to ordinary camera lenses as opposed to refractive error in an arbitrary thick-lens optical system bounded by air and fluid (i.e. the eye). In both the camera and the eye, "relative blur" was determined to be directly proportional to dioptric defocus and to aperture size, and effectively independent of the focal length. Distortion of imagery was also found to be independent of the focal length. Photographs corroborate the theoretic findings. A given amount of relative blur, however, appeared somewhat greater when recorded on photographic film than when appreciated by the human eye. The Stiles-Crawford effect, the chromatic aberration of the eye, and neural processing probably each contribute to this difference. Previous investigators have grossly exaggerated blur and distortion in photographs intended to simulate ocular imagery and have drawn misleading conclusions from their results.

Humans↗

PubMedDate not supplied

[Reproductive kinetics of differentiating chondrocytes in normal states and in exposure to lead acetate].

Parameters of the mitotic cycle of chondrocytes in the skeletal extremities of the rat foetuses were estimated in various experiments with 3H-thymidine. Lead acetate entering the organism during the gestation period influenced the mitotic cycle duration, increasing it at the expense of a presynthetic phase. A change in the proliferation rates delayed the bones' growth and affected the morphological structure of the forming epiphyseal cartilage.

Animals↗

PubMed1992

Structure of breeding programs to capitalize on reproductive technology for genetic improvement.

Potential rates of genetic progress are limited by biological constraints, which along with genetic parameters determine the structure of breeding programs to be employed for maximum genetic improvement. The objective here is to determine whether current progeny-testing programs in dairy cattle, which have been dictated and constrained by low female reproductive rates, need to be changed to capitalize on new reproductive technologies and how these changes should be implemented. Many differences between breeding programs diminish when selection on animal model genetic evaluations across all age and population groups is adopted as a strategy. Progeny-testing schemes then evolve toward dispersed open nucleus breeding schemes when multiple ovulation and embryo transfer is used on bull-dams. Nucleus breeding schemes have been advocated to capitalize on embryo transfer technology. In nucleus breeding schemes utilizing high reproductive rates, inbreeding, rather than reproductive rate, poses a limit to genetic progress, and strategies that maximize response to selection while limiting inbreeding need to be employed. One strategy is mating each dam to several sires rather than only one sire. In vitro embryo production techniques can be used to facilitate such mating strategies. Large-scale in vitro embryo production programs, in which large numbers of embryos per female are tested in the commercial population, offer the greatest potential for genetic gain with low rates of inbreeding. Cloning has an impact mainly on methods for dissemination of genetic improvement. Breeding herds, genetically inferior to marketed clones, are needed for continuous genetic gain. Reproductive technologies offer the potential for genetic improvement. Whether new breeding programs require changes in population structure, e.g., by creation of nucleus breeding herds, depends mainly on logistics and on quantity and quality of field information.

Animals↗

PubMed2005

Association between Beckwith-Wiedemann syndrome and assisted reproductive technology: a case series of 19 patients.

OBJECTIVE: An association between assisted reproductive technique (ART) and specific imprinting mutations, such as Beckwith-Wiedemann syndrome (BWS), has recently been documented. Based on experiments in farm animals that demonstrated an association between alterations in culture media during ART and large offspring syndrome, we hypothesized that the culture media could be implicated as a common factor among the children with BWS conceived after ART. DESIGN: Retrospective case series. SETTING: Registry from Academic Medical Center. PATIENT(S): Nineteen children born after ART were identified within the registry. MAIN OUTCOME MEASURE(S): Demographics of patients, type of ART, culture media, IVF parameters. RESULT(S): Twelve of the 19 medical records from the reproductive endocrine centers were successfully obtained. Ten of 12 mothers of children with BWS had IVF, but no single, consistent culture media was used in this group. Half of the patients underwent IVF with intracytoplasmic sperm injection (ICSI; n = 5), whereas the other half had routine IVF. One child was conceived through clomiphene citrate (CC) stimulation and artificial insemination, whereas another patient conceived through gonadotropin stimulation with intrauterine insemination (IUI). The gonadotropin dosage and quantity of embryos transferred also varied significantly. The only consistent finding was that all 12 women received some type of ovarian stimulation medication. CONCLUSION(S): Large epidemiologic studies are needed to further study the association between BWS and ART.

Adolescent↗

PubMed1991

Experimental pathogenicity of mollicutes from bovines with reproductive disorders in rabbit fallopian tube organ culture.

Mollicutes (10) belonging to Mycoplasma and Acholeplasma isolated from various reproductive disorders were tested in rabbit fallopian tube (FT) organ culture. Parameter for describing pathogenic status of Mollicutes in rabbit FT organ culture included multiplication of organisms, and its effect on ciliary activity along with histopathological changes in FT explants. M. mycoides (LC, Y-Goat), M. bovoculi, M. bovigenitalium, Mycoplasma sp. and A. oculi were categorized as pathogenic; A. axanthum and A. laidlawii as mildly pathogenic; and M. bovis, M. arginini. and A. granularum, as nonpathogenic to rabbit FT organ culture. Thus, rabbit FT organ culture is recommended for use as a suitable and economical in vitro model to assess the pathogenicity of Mollicutes of reproductive tract origin.

Animals↗

PubMed1995

Thyroidectomy abolishes seasonal testicular cycles of Soay rams.

The hypothesis that thyroid hormones are required for the expression of normal cycles of reproductive activity was tested in Soay rams, a widely used subject for studies on seasonality. Six rams were thyroidectomized and six sham-operated in October, just before the expected peak of reproductive activity. All were then placed in long days (18 h light and 6 h dark, 18L:6D) for 12 weeks and then transferred to short days (8L:16D). All animals exhibited an initial short-term increase in testicular size and serum concentrations of follicle-stimulating hormone and luteinizing hormone then, as expected, these parameters decreased in sham-operated animals for the remainder of the time they were maintained on long days. Four weeks after transfer back to short days, gonadotrophin concentrations in the control animals were significantly raised above the lowest level, and scrotal size increased after eight weeks. By contrast, in thyroidectomized rams all parameters remained high throughout the experiment. Thyroidectomy therefore abolished seasonal changes in reproductive activity, indicating a requirement for thyroid hormones for the normal expression of such patterns. It is unlikely that this was related to any generalized metabolic disturbances caused by thyroidectomy, as body masses were similar in both groups of animals throughout the experiment.

Animals↗

PubMed1996

Is leukocytospermia clinically relevant?

OBJECTIVE: To evaluate the relationship between seminal leukocytes and abnormal semen parameters in a large population of infertility patients. DESIGN: Prospective clinical study. SETTING: Center for Reproductive Medicine at Brigham and Women's Hospital, Boston, Massachusetts. PATIENT(S): One thousand seven hundred ten male partners in infertile couples attending the Center for Reproductive Medicine. MAIN OUTCOME MEASURE(S): Seminal leukocyte concentrations, sperm count, motility and morphology, and the prevalence of samples with < 10 x 10(6) motile sperm per ejaculate (a parameter defined by IVF as the most clinically significant predictor of male infertility). RESULT(S): There was a strong relationship between increasing leukocyte concentrations in semen and abnormal semen parameters. Statistically significant differences in sperm concentrations and morphology were observed at leukocytospermia thresholds of 5 x 10(5) and 2 x 10(6) granulocytes/mL, respectively. The percentage of suboptimal semen specimens as defined by IVF criteria (< 10(7) total motile sperm per ejaculate) significantly increased with increasing seminal granulocyte concentrations. A twofold increased prevalence in such suboptimal semen specimens was observed at the leukocytospermia threshold of 2 x 10(6) granulocytes/mL. CONCLUSION(S): There is a relationship between increasing seminal granulocyte concentrations and poor semen parameters. At seminal granulocyte concentrations > 2 x 10(6)/mL, semen parameter abnormalities were observed that were both statistically and clinically significant.

Fertilization in Vitro↗

PubMed2001

A comprehensive model of spastic hypertonia derived from the pendulum test of the leg.

We propose a comprehensive model of spastic hypertonia based on clinical neurophysiology and validated using experimental data obtained from the pendulum test of the leg in 8 healthy volunteers and 15 spastic patients. This nonlinear computational model includes mechanical parameters and a stretch reflex representation involving three neural parameters: a threshold coefficient, the gain of the stretch reflex, and a time lag accounting for the reflex loop latency and the electromechanical coupling delay. Variation of the threshold coefficient alone allowed an overall reproduction of experimental data obtained from spastic and healthy subjects. We propose that this parameter could represent the supraspinal drive, supposed to be preserved in control subjects and decreased in spastic patients. No subsequent variation of the reflex gain was required to simulate spastic traces. Adjustment of the time lag influenced the duration of the swinging phase and oscillatory phenomena possibly occurring during the pendulum test. It could be related to the involvement of either short- or long-latency stretch reflex loops. With respect to current neurophysiological concepts of motor control, this modeling approach may help in understanding mechanisms underlying spastic hypertonia, and in predicting the clinical effect of antispasticity agents.

Adult↗