Suppression of Richtmyer-Meshkov Instability via Special Pairs of Shocks and Phase Transitions.

The classical Richtmyer-Meshkov instability (RMI) is a hydrodynamic instability characterizing the evolution of an interface following shock loading. In contrast to other hydrodynamic instabilities such as Rayleigh-Taylor, it is known for being unconditionally unstable: regardless of the direction of shock passage, any deviations from a flat interface will be amplified. In this article, we show that for negative Atwood numbers, there exist special sequences of shocks which result in a nearly perfectly suppressed instability growth. We demonstrate this principle computationally and experimentally with stepped fliers and phase transition materials. A fascinating immediate corollary is that in specific instances, a phase-transitioning material may self-suppress RMI.

Spread of the Rat Lungworm (Angiostrongylus cantonensis) in Giant African Land Snails (Lissachatina fulica) in Florida, USA.

The rat lungworm (Angiostrongylus cantonensis) is a parasitic nematode that causes rat lungworm disease. It is the leading cause of eosinophilic meningitis and is a zoonotic health risk. We confirmed the presence of A. cantonensis using species-specific, quantitative PCR in 18 of 50 (36%) giant African land snails (Lissachatina fulica) collected from Miami, Florida, US in May 2013. These snails were collected from seven of 21 core areas that the Florida Department of Agriculture and Consumer Services monitor weekly. Rat lungworms have not previously been identified in these areas. Duplicate DNA extractions of foot muscle tissue from each snail were tested. Of the seven core areas we examined, six were positive for A. cantonensis and prevalence of infection ranged from 27% to 100%. Of the 18 positive snails, only five were positive in both extractions. Our results confirm an increase in the range and prevalence of rat lungworm infection in Miami. We also emphasize the importance of extracting sufficient host tissue to minimize false negatives.

Characterization of a new myxozoan species (Myxozoa: Myxobolidae: Myxosporea) in largescale stonerollers (Campostoma oligolepis) from the Mobile River Basin (Alabama).

Myxobolus stanlii sp. n. was described from largescale stonerollers ( Campostoma oligolepis ) from the Mobile River Basin in Alabama. The parasite was described using critical identifying morphological features, and the 18S small subunit ribosomal RNA (SSU rRNA) gene sequence. The spore body was ovoid, 10.03 ± 0.7 (7.5-11.0) µm long and 8.8 ± 1.5 (6.3-11.3) µm wide in frontal view. Spore thickness was 6.3 ± 2.7 (6.2-8.6) µm in sutural view. Polar capsules were pyriform, of equal size, and oriented in plane with the sutural ridge. Polar capsules were 2.45 ± 1.5 (range 2.1-4.3) µm in width and 4.6 ± 2.7 (range 4.5-6.9) µm in length. Based on the SSU rRNA gene sequence of Myxobolus stanlii sp. n. is most closely related to M. pseudodispar.

A new technique to evaluate the ability of cryoprotectors to prevent premature acrosome reaction in human spermatozoa.

Acrosome reaction (AR) induced by low temperature has been used to evaluate sperm function; it correlates adequately with the fertilization percentages in vitro. In this study, the technique of AR induction by low temperature was used to evaluate the effect in the protection of the acrosome by cryopreservatives normally used in human semen cryopreservation. Donor sperm selected by use of the migration sedimentation technique was incubated in human tubal fluid medium, added to dimethyl sulphoxide 1 m, ethylene glycol 0.75 m, glycerol 1 m, incubated at 4 degrees C and 20 degrees C (as a control) for 18 h, and then for 3 h at 37 degrees C in a cell incubator. The AR was evaluated by triple stain in 100 viable spermatozoa. The effect of cryopreservatives on acrosome preservation in samples incubated for 18 h at 4 degrees C was as follows: 78% intact acrosome for glycerol, 77.8% intact acrosome for dimethyl sulphoxide and 96.2% intact acrosome for ethylene glycol (P < 0.0025 compared with glycerol and dimethyl-sulphoxide). The sperm samples incubated with cryopreservatives for 18 h at 20 degrees C did not show an increase in the percentage of AR in samples incubated with glycerol and ethylene glycol, while a significant variation was observed in the sample incubated with dimethyl sulphoxide (P < 0.001). Additional incubation for 3 h at 37 degrees C significantly increased the AR only in the sample incubated with glycerol (P < 0.001). Acrosome preservation is essential in the fertilization process and the evaluation of acrosome reaction induction by low temperature test was satisfactory. This test proves that ethylene glycol presents a greater protective effect on the acrosome preservation of human spermatozoa.

Influence of tris(4-chlorophenyl)methanol, non-ortho PCB 77 and gamma-hexachlorocyclohexane on human sperm function in vitro.

In recent years, there has been growing concern that environmental pollutants in general, and organochlorines in particular, adversely affect male fertility. Therefore, we investigated the effects of tris(4-chlorophenyl)methanol (TCPM), non-ortho PCB 77 and gamma-hexachlorocyclohexane (gamma-HCH, lindane) on human sperm functions in vitro. Human spermatozoa from healthy donors were washed in human tubular fluid medium containing 1% human serum albumin, filtered through glass wool and exposed to different concentrations of TCPM, PCB 77 or gamma-HCH. After incubation for 5 h at 37 degrees C and 5% CO(2), sperm vitality and the percentage of living acrosome-reacted spermatozoa were examined using triple stain technique. Total sperm motility was evaluated by computer-assisted sperm analysis (Stroemberg-Mika) after 5 h. For TCPM, total motility was additionally measured after 18 and 40 h. Different concentrations of PCB 77 and gamma-HCH did not alter the percentage of spontaneous living acrosome-reacted spermatozoa, vitality and total motility. TCPM dose-dependently altered sperm motility, vitality and acrosome reaction. The percentage of living acrosome-reacted spermatozoa was increased at overtly toxic concentrations. Therefore, it is suggested that unspecific acrosomal loss has been induced by degenerative processes. In conclusion, even high concentrations of PCB 77 and gamma-HCH did not affect human sperm functions in vitro. Only very high cytotoxic TCPM concentrations modulated spontaneous acrosome reaction and total motility. Therefore, in vivo effects on human sperm function seem to be unlikely. However, individual susceptibility has to be considered and little is known about additive and possible synergistic effects as other environmental pollutants with similar potencies have been found in the human male and female reproductive tract.

Minmax designs for planning the second phase in a two-phase case-control study.

Two-phase designs, in which a subsample with validation or complete information data is sampled stratified both on outcome and covariate from a first-phase study with incomplete data, have been proposed over 10 years ago and have been proven to result in efficient estimates with respect to standard designs. The efficiency depends, however, on the sampling fractions within each stratum. Our aim is to present a strategy for obtaining an optimized design, i.e. sampling fractions, that makes use of available phase-one data of an existing case-control study considered as the first-phase sample when the focus is on estimating a parameter vector. No global optimal design exists and local optimal designs depend on scenarios comprising the true disease model and the association between the phase-one and phase-two information. We develop an admissibility test that rejects scenarios inconsistent with the phase-one data and, for the selected scenarios, determine a minmax D- or A-optimal design that protects against worst-case scenarios. This work is applied on two examples.

Influence of motility and vitality in intracytoplasmic sperm injection with ejaculated and testicular sperm.

The vitality of spermatozoa used for intracytoplasmic sperm injection (ICSI) is a crucial factor for fertilization, establishment and outcome of a pregnancy in assisted reproductive technique cycles. The sperm origin may also be a limiting factor, although little is known about this issue. It is known that the motility of injected spermatozoa and their origin from ejaculate or testicular biopsies are important predictors in terms of fertilization, pregnancy and birth rates. Oocytes of patients in 2593 cycles were retrieved in our in vitro fertilization programme and inseminated via ICSI. We used motile (group 1, n = 2317) or immotile ejaculated spermatozoa (group 2, n = 79), motile sperm retrieved from testicular biopsies (group 3, n = 62) and immotile spermatozoa from testicular biopsies (group 4, n = 135). Female age and number of oocytes retrieved did not differ significantly among the groups. The fertilization rates were as follows: 67.1% in group 1, 49.8% in group 2, 68.3% in group 3 and 47.8% in group 4. The pregnancy rates in cases where three embryos had been transferred amounted to 35.7% in group 1, 17.3% in group 2, 38.3% in group 3 and 20.5% in group 4. The embryo quality showed no differences between groups 1 and 3 (14.5), and between groups 2 (11.8) and 4 (10.8). The abortion rate was similar in groups 1-3, but increased in group 4 (26.6%, 27.3%, 31.6% and 55.5%). Irrespective of their origin, the fertilization potential of injected spermatozoa was found to be influenced by motility. The resulting pregnancy and birth rates, i.e. the potential of the resulting embryos to implant and to achieve viable pregnancies, seem to be additionally dependent on the sperm origin. This was well shown by declining rates when spermatozoa in a relatively early stage of maturity had been used. We see increasing evidence that the degree of sperm maturity has an important impact on the outcome of ICSI. In obstructive azoospermia, spermatozoa retrieved from the epididymis should be used rather than testicular biopsy spermatozoa, or testicular sperm should be preincubated in culture medium before ICSI.

Atopic dermatitis -- topical therapy: do patients apply much too little?

BACKGROUND: The treatment of atopic dermatitis still remains a challenge. Little research has been done on the issue of the extent to which patients correctly use prescribed topical preparations under everyday conditions. AIMS: To investigate what quantity of topical preparations is applied by outpatients in daily routine treatment over a 26-week period and to what extent this consumption is related to the course of the severity of patients' skin conditions. METHODS: Thirty adult outpatients (20 female and 10 male) with atopic dermatitis were examined at four different times during 26 weeks. For treatment and skin care these patients were given a topical glucocorticoid preparation (prednicarbate) and the corresponding emollient. RESULTS: The average severity rating (SCORAD) was 29.6 (before therapy 33.9, after 26 weeks 27.4). The SCORAD indices improved by a mean of 6.5 points (p<0.05). CONCLUSION: Patients who applied the correct amount of the prednicarbate-containing preparations (not less than 90% of 0.5 g/dm(2)) to the areas of affected skin showed a significant improvement in SCORAD indices across the four measuring times.

Improvement of semen quality by nocturnal scrotal cooling in oligozoospermic men with a history of testicular maldescent.

For infertile men with a history of testicular maldescent only few therapeutic options exist beside assisted reproduction. The aim of our study was to evaluate the influence of nocturnal scrotal cooling on semen quality in such patients presenting with oligozoospermia. Twenty infertile men with a history of testicular maldescent and oligozoospermia were included for nocturnal scrotal cooling over 12 weeks for every night. To increase nocturnal periscrotal air circulation we used a membrane pump connected via plastic tubes to receptacles placed in both groins. Semen analysis was performed at the beginning of the cooling period and at weeks 4, 8 and 12. Another 20 infertile patients with a history of testicular maldescent and oligozoospermia were followed without specific treatment and served as a retrospectively built control group. Scrotal cooling at night by means of a perigenital air stream resulted in a scrotal temperature drop by 0.8 degrees C (median). A significant increase in sperm concentration and total sperm count was achieved by nocturnal cooling after 8 weeks (p < 0.01; p < 0.05; respectively) and 12 weeks (p < 0.01; p < 0.01; respectively). The improvement of sperm motility and sperm morphology was statistically insignificant. The present study suggests nocturnal scrotal cooling as a therapeutic option to improve semen quality. In a further controlled prospective study the influence on pregnancy rates should be evaluated.

Personality, coping and sperm count.

Previous research has suggested an association between personality traits and coping, as well as between coping and sperm concentration. In the present study, both domains of research were combined, leading to the formulation of specific hypotheses. A total of 54 healthy volunteers were given questionnaires twice to assess personality traits and coping behaviour. Participants also produced up to three semen specimens. As hypothesized, active coping was correlated negatively with neuroticism (r = -0.59) and positively with conscientiousness (r = 0.56), whereas sperm concentration was correlated negatively with both active coping (r = -0.28) and conscientiousness (r = -0.37). The relationship between conscientiousness and sperm concentration did not appear to be mediated by active coping. Although the correlations were small, evidence is mounting that psychological aspects and male sperm parameters are not independent. The present findings, however, should not lead to the conclusion that conscientiousness and active forms of coping are characteristics of infertile patients.

Influence of the type of undertrousers and physical activity on scrotal temperature.

BACKGROUND: Testicular temperature correlates highly with scrotal temperature. The aim of this study was to evaluate the influence of the type of undertrousers on scrotal temperature during standardized periods of sitting and walking. METHODS: Fifty volunteers without a history of infertility and normal andrological examination were included for scrotal temperature evaluation. Temperatures were measured every minute with a portable data recorder connected with two thermistor temperature sensors, which were attached on either side of the scrotum. Ambient temperature in the study room was adjusted to 20 degrees C throughout the whole experiment. All volunteers started the experiment at the same time of day. Clothing of the volunteers consisted of standardized cotton wool trousers and shirts fitting to body size. Each volunteer performed six periods of 45 min, either walking on a treadmill (3.0 km/h) or sitting, and wearing in a standardized and randomized manner either tight, loose fitting or no undertrousers respectively. RESULTS: The following interactions were demonstrated by means of multivariate analysis of variance for repeated measurements: scrotal temperatures were significantly higher for tight versus loose fitting versus absent undertrousers. Furthermore, significantly lower scrotal temperatures were identified for walking versus sitting as well as for the right versus the left scrotal side. CONCLUSIONS: The present study suggests that wearing tight fitting undertrousers is associated with higher scrotal and consequently testicular temperatures than wearing loose fitting undertrousers or none.

The male reproductive system and its susceptibility to endocrine disrupting chemicals.

In the past years, there has been increased interest in assessing the relationship between impaired male fertility and environmental factors. Human male fertility is a complex process and therefore a great variety of sites may be affected by exogenous noxae. Lifestyle factors as well as various environmental and occupational agents may impair male fertility. Many studies have been published reporting on reproductive dysfunctions in male animals and humans. Especially environmental pollutants with endocrine activity are discussed as a possible cause of this detrimental development. Evidence from animal experiments show that substances with oestrogenic and antiandrogenic properties may cause hypospadia, cryptorchidism, reduction of sperm density and an increase of testicular tumours. Many adverse effects on animal male fertility have been documented for phthalates and some chlorinated hydrocarbons such as polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins. For other chemicals such as bisphenol A and nonylphenols animal data are conflicting. Environmental pollutants may mediate their effects by receptor binding, modulation of hormone-regulated mechanisms or direct toxic effects. Data on environmental chemicals and human male fertility are scarce, and risk assessment is mostly based on the results of animal studies. However, there are indications that exposure to endocrine active chemicals during early development may alter hormone responsiveness in adulthood. Furthermore, some of the chemicals are found in fluids that are associated with human reproduction, such as follicular fluid, seminal fluid and cervical mucus. Recent studies suggest a correlation between pesticide exposure and standard semen parameters as well as in vitro fertilization rates.

Alpha-glucosidase in the human epididymis: topographic distribution and clinical application.

Alpha-glucosidase activity (EC.3.2.1.20) is present in human seminal plasma, and the neutral form of the enzyme originates almost exclusively from the epididymis. In this study, the specific immunocytochemical location of alpha-glucosidase in the human epididymis was evaluated using a polyclonal antibody. Furthermore, a spectrophotometric assay was employed to assess epididymal obstruction in infertile patients. The enzymatic activity of alpha-glucosidase free of prostate isoform (AGFPI) was determined spectrophotometrically at 405 nm. According to AGFPI activity, patients with leucocytospermia, oligozoospermia and azoospermia were recorded as having normal values or low values indicating epididymal obstruction. Specific immunochemistry staining was demonstrated in the cytoplasmic cells at the epithelial level, in the transition area and in the efferent ducts. The values of the three groups and the control were as follows (mean +/- SEM): normozoospermia (control): 20.2 +/- 1.4 mU ml(-1); azoospermia: normal value: 17.6 +/- 2.2 mU ml(-1), low value: 7.4 +/- 1.8 mU ml(-1); oligozoospermia: normal value: 22.3 +/- 2.5 mU ml(-1), low value: 7.3 +/- 0.7 mU ml(-1); leucocytospermia: increase value: 38.9 +/- 3.7 mU ml(-1), low value: 11.1 +/-1.3 mU ml(-1). This study suggests that determination of alpha-glucosidase might be helpful to evaluate functions of the epididymis and particularly to exclude epididymal obstruction.

Comparative susceptibility of Atlantic salmon, lake trout and rainbow trout to Myxobolus cerebralis in controlled laboratory exposures.

The susceptibility of lake trout Salvelinus namaycush, rainbow trout Oncorhynchus mykiss and Atlantic salmon Salmo salar to Myxobolus cerebralis, the causative agent of whirling disease, was compared in controlled laboratory exposures. A total of 450 (225 for each dose) fry for each species were exposed to a low (200 spores per fish) or high (2000 spores per fish) dose of the infective triactinomyxon. At 22 wk post-exposure, 60 fish from each group, as well as controls for each species, were examined for clinical signs (whirling behavior, blacktail, deformed heads and skeletal deformities), microscopic lesions, and presence of spores. Rainbow trout were highly susceptible to infection, with 100% being positive for spores and with microscopic pathological changes in both exposure groups. Rainbow trout were the only species to show whirling behavior and blacktail. Atlantic salmon were less susceptible, with only 44 and 61% being positive for spores, respectively, in the low and high dose groups, while 68 and 75%, respectively, had microscopic pathology associated with cartilage damage. Rainbow trout heads contained mean spore concentrations of 2.2 (low dose) or 4.0 (high dose) x 10(6) spores g tissue(-1). The means for positive Atlantic salmon (not including zero values) were 1.7 (low) and 7.4 (high) x 10(4) spores g tissue(-1). Lake trout showed no clinical signs of infection, were negative for spores in both groups and showed no histopathological signs of M. cerebralis infection.

Urogenital inflammation: changes of leucocytes and ROS.

The presence of excess leucocytes in the semen has been associated with male infertility. According to the WHO, concentrations of more than 106 leucocytes ml-1 are considered as leucocytospermia, indicating genital tract infections. Up to now, no consensus has been achieved on how leucocytes should be quantified in semen. Using the peroxidase staining and monoclonal antibodies to CD15, CD45 and CD68, we found significant differences between the detection methods. Only 47.4% of the semen samples that were assessed as leucocytospermic by CD45 were identified as such by peroxidase staining. The concentration of peroxidase-positive cells was significantly correlated with polymorphonuclear granulocyte (PMN) elastase (P < 0.0001). However, a negative correlation of peroxidase-positive cells with the sperm concentration was only found in oligozoospermic patients (P < 0.0001). Moreover, the slightly positive correlation with normal sperm morphology seems to be applicable only in cases of oligozoospermia. Significant negative correlation of the number of peroxidase-positive cells were found for both maximal inducible acrosome reaction (P = 0.0219) and the inducibility of acrosome reaction (P = 0.0370), indicating a rather deleterious effect of leucocytes on this important sperm function. Concerning the result in the in vitro fertilization programme, none of the examined parameters (PMN elastase, concentration of round cells and peroxidase-positive cells) showed a correlation with either fertilization or pregnancy. This result seems to be reasonable as severely damaged spermatozoa and leucocytes are eliminated from the ejaculate by different sperm separation methods. Interestingly, a significant negative correlation of the TUNEL assay as a measure of sperm DNA fragmentation was found only with pregnancy (P = 0.006) but not with fertilization. As DNA fragmentation can also be caused by ROS that are generated by leucocytes, this causality should not be neglected.

Are children of older fathers at risk for genetic disorders?

Genetic risks related to paternal age should be of interest to clinical andrologists counselling older men who wish to father a child. Theoretically, the number of (pre-meiotic) mitotic cell divisions during spermatogenesis and their remarkable increase with ageing compared with oogenesis would be in favour of genetic risks for the offspring of older men. But for numerical and structural chromosomal anomalies, such an influence of paternal age has not been found. However, in several autosomal dominant disorders affecting three specific genes (fibroblast growth factor receptor 2 and 3, RET proto-oncogene) the risk for a child to be affected increases with paternal age at time of birth. For other autosomal dominant -X chromosomal dominant or recessive disorders, the available data are sufficient to support the concept of a positive relationship between paternal age and de novo gene mutations. Studies analysing gene sequences of affected children and their parents would allow further evaluation of this topic. The impact of paternal age on disorders with a complex genetic background, however, is a matter of debate. A significant effect of paternal age could not be shown for nonfamilial Alzheimer's disease, congenital heart defects, nonfamilial schizophrenia, acute lymphoblastic leukaemia or prostate cancer.