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PubMed1982

Objective evaluation of spermatozoa motility as influenced by fresh blood serum and normal saline.

In order to investigate the effect of fresh blood serum and normal saline on the motility of ejaculated spermatozoa, semen samples were collected from 7 fertile males, aged 25-39 yrs. Each sample was divided into 5 aliquots: one aliquot remained undiluted, and fresh blood serum from fertile men and normal saline were added to the others to produce 1:1 and 3:1 dilutions. Spermatozoal motility was evaluated objectively, every hour and for 4 h after ejaculation, by the multiple exposure photography method. It was found that serum from fertile men as well as normal saline caused a significant increase of spermatozoal velocity. However, spermatozoal velocity under the influence of serum from fertile men changed with time in a different way than in the undiluted aliquot and those diluted with normal saline. Thus, the beneficial effect of fresh blood serum on spermatozoal velocity, cannot only be attributed to the lowering of seminal viscosity and the reduction of sperm concentration caused by dilution, but to various substances present in blood serum.

Adult↗
PubMed1996

Mapping of polyomavirus DNA replicative intermediates by two-dimensional gel analysis using chemiluminescent detection.

Py DNA replicative intermediates (RIs) were mapped using a neutral/neutral two-dimensional (N/N 2D) technique by both chemiluminescent and radioactive detection. The nonradioactive method provides similar sensitivity to radioactive methods while possessing the advantages of stability of labeled probes, faster processing, multiple exposures, easy disposal and safety associated with nonradioactive detection. Application of this method to 2D gel analysis requires some technical modification to reduce background and save the substrate. The patterns of Py RIs with Afl II digestion suggest that bidirectional replication occurs during Py DNA synthesis in cell culture, but other unexpected structures of DNA replication are also seen.

Animals↗
PubMed1991

Hydroa vacciniforme: an unusual clinical manifestation.

Hydroa vacciniforme is a rare, chronic photodermatosis with onset in childhood that is characterized by recurrent vesiculation, necrosis, and vacciniform scarring limited to sun-exposed skin. We report a case of nonvesicular hydroa vacciniforme in which only extensive crusting associated with hypertrophic scarring on sun-exposed skin was present. Multiple exposures to UVA, however, reproduced lesions with the typical clinical and histologic features of hydroa vacciniforme. Results of blood, urine, and fecal porphyrin studies were normal.

Administration, Cutaneous↗
PubMed1988

Responses of field-grown Medicago sativa L. to acidic fog and ambient ozone.

The relationship between pollutant-induced leaf drop or reductions in foliar pigment concentrations and yield was determined for field-grown alfalfa (Medicago sativa L. 'Moapa') exposed to simulated fogs of pH 7.24, 2.69 and 1.68 singly, and in combination with ambient ozone (O3) over an 11-week period. Highly acidic fog (pH 1.68) or ambient O3 significantly reduced totalseason dry yield and foliar pigment concentrations, and increased leaf drop. Significant interactive effects between acidic fog and O3 were observed for the leaf parameters, but not for yield. Thus, multiple exposures to acidic fog at current ambient levels of acidity (i.e. pH 2.69) could effect leaf quality in the absence of significant effects on yield. Alternatively, O3-induced effects on leaves may have utility as bioindicators of potential yield losses.

Journal Article↗
PubMed1983

Behavioral, but not physiological, adaptation to repeated separation in mother and infant primates.

Mother and infant squirrel monkeys were subjected to a series of brief separations in order to evaluate how behavioral and physiological responses change following multiple exposures to stress. Beginning when the infants reached three months of age, their behavioral and hormonal responses were assessed during six 1-hr separations; and additional five dyads served as controls for the effect of repeated disturbance. The separated infants showed a marked and progressive decrease in distress calling across time, but no change was observed in the high levels of agitated activity or the plasma cortisol response to separation. This finding questions the traditional use of distress vocalizations as a measure of stress and indicates that certain types of behavior can change independently of physiological arousal responses, which may continue to occur even after repeated exposures to stress.

Adaptation, Psychological↗
PubMed1986

Unmasking AIDS: chemical immunosuppression and seronegative syphilis.

In both African AIDS populations and homosexual populations outside of Africa, a high incidence of syphilis and multiple exposures to infectious diseases results in frequent, often abusive use of antibiotics. Epidemiological evidence exists for chemical immunosuppression resulting from antibiotics and other prescribed and recreational drugs prior to the current AIDS crisis. Analysis and review of literature is given on the effects of subcurative doses of antibiotics masking and distorting the expression of secondary and tertiary syphilis. A high incidence of seronegative syphilis is found in Africa and compares with Western reports of seronegativity and persistence of treponemes despite adequate antibiotic therapies. Late latent and tertiary syphilis produce symptoms and immunosuppression comparable to that seen in the current AIDS crisis. Screening procedures instituted for a group of gay men with AIDS and AIDS related conditions is revealing evidence of chemically immunosuppressed syphilis as a factor in AIDS. Key words: AIDS, immunosuppression, syphilis, chemical immunosuppression, seronegativity, immunosuppressive sera, etiology of AIDS.

AIDS-Related Complex↗
PubMed1987

Embryotoxic evaluation of a Prudhoe Bay crude oil in rats.

The embryotoxic potential of a Prudhoe Bay crude oil (PBCO) was investigated in rats. PBCO was administered orally to pregnant rats as (i) a single dose on various gestation days, (ii) a single variable dose on gestation day 6, or (iii) as daily doses from day 6 to day 17 of pregnancy. PBCO administered during the earlier stages of pregnancy (day 3, 6 or 11) but not during the later stages, affected the reproductive performance of pregnant rats by significantly increasing the number of resorptions including fetal death and by decreasing the fetal weight. A dose-dependent increase in fetomortality was also observed. Multiple exposure to low levels of crude oil also caused a significant reduction in maternal body weight besides other embryotoxic changes.

Administration, Oral↗
PubMed2005

Effect of the anticoagulant, pindone, on the breeding performance and survival of merino sheep, Ovis aries.

The effect of the anticoagulant, pindone, on the breeding performance and survival of relatively free-ranging merino sheep was assessed. Pindone (2-pivalyl-1, 3-indandione) was administered orally as a single (10, 3, or 2 mg pindone kg(-1) over three consecutive days) or multiple exposure (dosing regime repeated after a further 8 days). Prothrombin times (PT) increased up to 4-fold in treated sheep, and haemorrhage occurred in some instances, particularly with the double dose treatment. Deaths of sheep also occurred, usually when the sheep were placed under added stress, particularly that associated with shearing. The breeding performance of pregnant ewes dosed with pindone was reduced, mainly due to an increase in stillborn and nonviable lambs (i.e. deaths within 2 days of birth). The motility of sperm in treated rams was also affected. Pindone persisted in the blood (maximum, 13.2 mg L(-1)) for up to 14 days after the last dose, and the half-life (t1/2) was estimated at approximately 5 days depending upon the dosing regime. Other tissue residues ranged from 17 (fat) to 39 (liver) mg kg(-1). The implications of these findings for ongoing responsible use of pindone (anticoagulants) in pest control programs are also discussed.

Animals↗
PubMed2005

Pesticide prioritization for a case-control study on childhood leukemia in Costa Rica: a simple stepwise approach.

Multiple exposures and rapidly changing use patterns are obstacles for adequate recall of pesticide exposures in epidemiologic studies. We present a simple stepwise approach for prioritization of pesticides as part of the exposure assessment strategy in an ongoing case-control study on pesticides and childhood leukemia in Costa Rica. Pesticide imports between 1977 and 2000, approximately the pertinent exposure period, were surrogates for use data. In the first phase, 323 active ingredients were identified, of which 219 were eliminated based on low usage and absence or negative results in a preliminary search in three major toxicity databases. In the second phase, the remaining 104 pesticides underwent scoring for their toxicodynamic potential (TDP) with regard to carcinogenicity, mutagenicity, and teratogenicity, weighted in this order. Bioavailability was assessed when TDP was multiplied by a weight for persistence and bioaccumulation, producing the intrinsic toxic potential (ITP). ITP was multiplied by an index of quantity (QI) of pesticide used in the exposure period, resulting in a weighted toxic potential (WTP). The top 25 positions in each of the four rankings (TDP, ITP, QI, and WTP) yielded together 64 highest-priority pesticides. This prioritization process has to be complemented with a further breakdown into crop-, time-, and biocide-specific shortlists to achieve a recall tool suitable for developing countries. Different parameters for prioritization assure inclusion of all relevant pesticides with regard to toxicity and bioavailability. The method contributes to cancer epidemiology in developing countries with access to basic use data and the Internet. The method is adaptable to other health outcomes.

Agriculture↗
PubMed2005

Tea polyphenol epigallocatechin 3-gallate impedes the anti-apoptotic effects of low-grade repetitive stress through inhibition of Akt and NFkappaB survival pathways.

V79 Chinese Hamster lung fibroblasts were subjected to repetitive low-grade stress through multiple exposures to 30 microM H2O2 in culture for 4 weeks. Akt/protein kinase B became phosphorylated at serine473 and threonine308 during this period of repetitive stress. Concurrent exposure of the cells to LY294002 (5 microM), a phosphoinositide-3 kinase inhibitor or 4.5 microM epigallocatechin 3-gallate (EGCG), a tea polyphenol almost completely blocked Akt activation by repetitive stress. Phosphorylation of I kappa B kinase (IKK) and transcriptional activity driven by nuclear factor kappa B (NFkappaB) were significantly enhanced by repetitive oxidative stress. These increases were largely abolished by simultaneous exposure to EGCG. The repetitively stressed cells demonstrated a significant resistance to apoptosis by subsequent acute stress in the form of ultraviolet radiation at 5 J/m2 or H2O2 (7.5 mM). The resistance to apoptosis conferred by repetitive stress was drastically reduced (>80%) by constant exposure to EGCG during the stress period while the presence of LY294002 or the NFkappaB inhibitor SN50 brought about a relatively moderate effect (about 50-65%). Our data indicate that activation of Akt and NFkappaB pro-survival pathways by repetitive low-grade stress results in a strong inhibition of the normal apoptotic response after subsequent acute stress. The tea polyphenol EGCG impedes the activation of both Akt and NFkappaB by repetitive stress and as a result preserves the normal apoptotic response during subsequent acute stress.

1-Phosphatidylinositol 4-Kinase↗
PubMed2006

Classification of continuous diffraction patterns: a numerical study.

The very intense and short pulses of future X-ray free electron lasers may allow the atomic resolution imaging of small, non-periodic objects. Preliminary estimates show that images obtained from single pulses do not contain statistically enough photons to allow successful reconstruction. Therefore multiple exposures of randomly oriented identical replicas have to be taken and the individual images have to be classified according to the object's orientation. The classification has been analytically treated by Huldt et al. [Huldt, G., Szoke, A., Hajdu, J., 2003. J. Struct. Biol. 144, 219.]. In this paper we extend the analytical results with numerical model calculations. This allows us to simulate realistic situations, which we will face in real experiments. We find significant deviations from the analytical expectations, even in the ideal case of spherical particles with random atomic distributions. We introduce a new norm for the individual scattering patterns and describe a criterion to select images belonging to similar orientation, which makes the classification more reliable in practice. We also discuss the effects of particle shape and size, partial orientational ordering, the measurement's resolution and the charge error caused by the Coulomb explosion.

Imaging, Three-Dimensional↗
PubMed2005

Use of the ascending aorta as bypass inflow for treatment of chronic intestinal ischemia.

PURPOSE: Surgical revascularization of intestinal arteries is an effective long-term treatment for chronic intestinal ischemia (CII) regardless of the technique used. Conventional antegrade or retrograde bypass techniques are the most common modalities for extensive lesions that cannot be treated by endarterectomy or transposition. In this report, we describe our experience with an antegrade bypass technique from the ascending aorta in patients with no other available inflow. METHODS: From April 1990 to May 2004, we performed antegrade bypass from the ascending aorta to the celiac artery, superior mesenteric artery (SMA), or both in five patients. These cases accounted for 2.4% of the 211 patients who underwent surgery on intestinal arteries during the study period. RESULTS: Four patients presented with symptomatic CII, and one patient had no intestinal ischemic symptoms. The underlying disease was Takayasu disease in two cases, Erdheim-Chester disease in one case, chronic aortic dissection in one case, and atherosclerosis in one case. Two patients had already undergone an unsuccessful revascularization attempt with another technique. Bypass was performed alone in three cases in association with revascularization of the ascending aorta, aortic arch, and proximal descending thoracic aorta in one case and in association with revascularization of the ascending aorta and proximal aortic arch and renal autotransplantation in one case. Recovery was uneventful in all cases. One venous graft occluded because of technical defects and required reoperation for prosthetic graft replacement on the 10th postoperative day. Symptoms of CII resolved in all cases. Four months after the procedure, one patient underwent dilatation of an asymptomatic stenosis of the SMA distal to the bypass. During the 50th month after the procedure, a new re-stenosis of the SMA appeared. Left untreated, this stenosis led to asymptomatic occlusion of the mesenteric segment of a sequential aortoceliomesenteric bypass 13 months later. This aortoceliac bypass and the other four bypasses were patent after 4, 31, 46, 52, and 120 months of follow-up. CONCLUSION: Antegrade intestinal artery bypass from the ascending aorta is an effective alternative for patients who have no other available inflow for conventional antegrade or retrograde bypass and for patients in whom major technical difficulties are likely after multiple exposures of the thoracoabdominal aorta. Although indications are uncommon, antegrade intestinal artery bypass can provide durable revascularization of the intestine.

Adult↗
PubMed2005

Evidence of apoptotic effects of 2,4-D and butachlor on walking catfish, Clarias batrachus, by transmission electron microscopy and DNA degradation studies.

Apoptosis or programmed cell death is characterized morphologically by chromatin condensation, cell shrinkage, fragmentation of the nucleus and cytoplasm, and consequently formation of apoptotic bodies. It has also been best characterized by the cleavage of DNA into nucleosomal size fragments of 180-200 bp or multiples of the same. Contrary to this, under extreme conditions, the cells were found to show adaptive response to apoptosis and unable to regulate their own death; necrosis is therefore predominantly observed. In the present study, we showed induction of apoptosis in Clarias batrachus due to sublethal concentration of 2,4-D and butachlor at multiple exposure time. The first phase of the study involved light microscopy (LM) and transmission electron microscopy (TEM) for ultrastructural abnormalities of the germinal tissues. While, in the second phase of the study, DNA degradation of blood and hepatic tissue was resolved on agarose gel electrophoresis. In histopathological studies, large numbers of stage II oocytes were noted for nuclear blebbing irrespective of the test chemical. Some of the butachlor-exposed oocytes showed vacuolation and electron dense cytoplasm along with thickened nuclear envelope, having close association with the lysosomes on the cytoplasmic side. Some oocytes undergo nuclear blebbing having inner dense core and translucent cytoplasm. Leydig cells were slightly hypertrophied and few appeared pycnotic, a process involving necrotic changes in which the cell nuclei were characterized by rounding up and condensation resulting in hyperchromatic staining or pycnosis. In testicular tissue, spermatogonial nuclei had irregular large clumps of heterochromatin adjoining the nuclear membrane indicating initial stage of apoptotic cell death. Electrophoretic separation resulted in a ladder pattern of blood DNA and smear like pattern of hepatic DNA. These results indicate that the above herbicides are able to induce apoptosis both at molecular as well as cytological level. A reference dose or safety factor approach to calculate risk of human exposure to both chemicals is still awaited.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2006

Cellular action of cholecystokinin-8S-mediated excitatory effects in the rat periaqueductal gray.

The peptide cholecystokinin (CCK) is one of the major neurotransmitters modulating satiety, nociception, and anxiety behavior. Although many behavioral studies showing anti-analgesic and anxiogenic actions of CCK have been reported, less is known about its cellular action in the central nervous system (CNS). Therefore, we examined the action of CCK in rat dorsolateral periaqueductal gray (PAG) neurons using slice preparations and whole-cell patch-clamp recordings. Application of CCK-8S produced an inward current accompanied by increased spontaneous synaptic activities. The CCK-8S-induced inward current (I(CCK)) was recovered after washout and reproduced by multiple exposures. Current-voltage plots revealed that I(CCK) reversed near the equilibrium potential for K(+) ions with a decreased membrane conductance. When several K(+) channel blockers were used, application of CdCl(2), TEA, or apamin significantly reduced I(CCK). I(CCK) was also significantly reduced by the CCK(2) receptor antagonist, L-365,260, while it was not affected by the CCK(1) receptor antagonist, L-364,718. Furthermore, we examined the effects of CCK-8S on miniature excitatory postsynaptic currents (mEPSCs) in order to determine the mechanism of CCK-mediated increase on synaptic activities. We found that CCK-8S increased the frequency of mEPSCs, but had no effect on mEPSC amplitude. This presynaptic effect persisted in the presence of CdCl(2) or Ca(2+)-free bath solution, but was completely abolished by pre-treatment with BAPTA-AM, thapsigargin or L-365,260. Taken together, our results indicate that CCK can excite PAG neurons at both pre- and postsynaptic loci via the activation of CCK(2) receptors. These effects may be important for the effects of CCK on behavior and autonomic function that are mediated via PAG neurons.

Animals↗
PubMed2006

Development of local knowledge of environmental contamination in Sydney, Nova Scotia: environmental health practice from an environmental justice perspective.

In Sydney, Nova Scotia, from 1901 through 1988 a coke and steel factory operated with no pollution controls, depositing over a million tons of particulate matter and releasing several thousands of tons of coal tar into the estuary. Previously we documented the presence of lead, arsenic and PAHs, in soil above Canadian guidelines, and in house dust in the communities surrounding the site [Lambert, TW, Lane, S. Lead, arsenic, and polycyclic aromatic hydrocarbons in soil and house dust in the communities surrounding the Sydney, Nova Scotia, tar ponds. Environ Health Perspect 2004; 112:35-41.]. In this paper we further the research by documenting and developing community knowledge with a study of resident's observations and experiences of the industrial contamination. We conducted two surveys, a quantitative door-to-door survey and qualitative dust interview, designed to complement each other and bring together the observations and experiences in the different communities to develop the local knowledge. The combined methodology uses techniques from both social and physical science, and was developed with the cooperation of community members. The research supports the proposition that local knowledge adds contextual meaning that complements the physical measurement of environmental contaminants, in order to understand the complex environment in which people live, and the multiple exposure pathways through which they can be affected. Residents in all three communities provided vivid observations and detailed experiences of the industrial pollution in their community and homes. The local knowledge is consistent with our physical data and review of the historical scientific research in Sydney, and supports the inference that the community was adversely impacted by the coke and steel facility. From a justice perspective, the three communities should be equally considered for remediation as part of the 'tar pond remediation policy' rather than the current policy of including only a few streets and houses.

Air Pollution, Indoor↗
PubMed2006

The effect of stress on the acute neurotoxicity of the organophosphate insecticide chlorpyrifos.

A study was conducted to determine if multiple exposures to several stress paradigms might affect the anticholinesterase effect of subsequently administered organophosphate insecticide chlorpyrifos. Male Sprague-Dawley rats were subject to daily periods of restraint, swimming, a combination of the two, or neither of the two (controls) (n=8/group) for 5 days per week over a six-week period. The most profound stress, as measured by reduced body weight gain and elevated levels of plasma corticosterone, was swimming. On day 39 of the study, shortly after the daily stress episode, one half of the rats in each group was dosed with 60 mg/kg chlorpyrifos subcutaneously. This had no effect on subsequent levels of plasma corticosterone. There were no stress-related differences in the degree of chlorpyrifos-induced inhibition of brain acetylcholinesterase in animals sacrificed on day 43.

Acetylcholinesterase↗
PubMed1985

Accumulation and elimination of macromolecular lesions in susceptible and non-susceptible rat tissues after repeated administration of trans-4-acetylaminostilbene.

Trans-4-acetylaminostilbene (trans-AAS) is a potent carcinogen and quite specifically produces sebaceous gland tumors, predominantly in the Zymbal's gland of rats. It is also acutely toxic to the rat glandular stomach. Recent results have shown that these target tissues are not notably exposed to reactive metabolites after single administration of the compound. Therefore, experiments were designed to test whether multiple exposures cause changes in metabolic activation or repair of DNA-bound metabolites to the effect that target and non-target tissues accumulate macromolecular damage differently. Trans-[3H]AAS was orally administered to female Wistar rats in 12 doses over 6 weeks and binding of metabolites to proteins, RNA and DNA in several tissues as well as the pattern of adducts in liver nucleic acids were measured. In addition, the elimination of macromolecular-bound metabolites was determined at various intervals during the treatment. Metabolism and clearance of bound metabolites remained unaltered. As a consequence, DNA-bound metabolites accumulated in all tissues measured; to the greatest extent in the non-target tissues liver and kidney. Tissue exposure, as estimated by protein-binding, differed by a factor of 10 and decreased in the following order: liver, kidney, lung, Zymbal's gland, glandular stomach, mammary tissue. The results support the notion that neither the extent nor the persistence of DNA-binding correlate with the biological effects of trans-AAS.

Animals↗
PubMed1986

The effect of ultraviolet radiation on humoral immune responses to T-dependent antigens.

Multiple exposures to broadband ultraviolet (uv) radiation resulted in alterations in the ability of BALB/c mice to produce antibodies to the T-dependent antigens ovalbumin and sheep erythrocytes following intraperitoneal, intradermal, and intravenous inoculation. A number of differences were observed in the influence of uv radiation on the specific cells producing antibody, as opposed to pure serological analyses. While both enhancement and reduction of the humoral response occurred, the experiments have suggested that the alterations in antibody responses following uv irradiation appear to be dependent on the nature of the antigen, the route of antigen administration, and the sometimes transient nature of the responses. The intradermal route of antigen inoculation was under the greatest influence of uv radiation.

Animals↗