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At least 811 records · Page 45Linked to original sources
PubMed2002

Toxicity of Nerium oleander leaf extract in mice.

Non-lethal dose of 70% ethanol extract of the Nerium oleander dry leaves (1000 mg/kg body weight) was subcutaneously injected into male and female mice once a week for 9 weeks (total 10 doses). One day after the last injection, final body weight gain (relative percentage to the initial body weight) had a tendency, in both males and females, towards depression suggesting a metabolic insult at other sites than those involved in myocardial function. Multiple exposure of the mice to the specified dose failed to express a significant influence on blood parameters (WBC, RBC, Hb, HCT, PLT) as well as myocardium. On the other hand, a lethal dose (4000 mg/kg body weight) was capable of inducing progressive changes in myocardial electrical activity ending up in cardiac arrest. The electrocardiogram abnormalities could be brought about by the expected Na+, K(+)-ATPase inhibition by the cardiac glycosides (cardenolides) content of the lethal dose.

Animals↗
PubMed2003

Navy hearing conservation program: hearing threshold comparisons to Navy SEALS and divers.

The study examined hearing threshold for Navy special operations personnel (SEALS (Sea-Air-Land): N = 212; divers: N = 165). Hearing threshold values were obtained and age adjusted using Mantel Haenzel Weighted odds ratio (MHOR) to compare with information in the Navy Hearing Conservation Database. For any threshold above 20 dB in the 500 through 3000 Hz range, the SEALS were significantly less at risk (MHOR = 0.54, p = 0.022) in the right ear, while the divers were significantly less at risk in the left ear (MHOR = 0.61, p = 0.047). For hearing thresholds at 4000 Hz above 40 dB, SEALS were significantly more at risk in both left ear (MHOR = 2.03, p = 0.0043) and right ear (MHOR = 2.58, p = 0.000089), while divers were not different. Risk assessment based on these findings must consider the multiple exposure hazards and critical mission profiles for the Navy special operations personnel. Requirements for mission accomplishment in hazardous environments may deem these risks acceptable.

Adolescent↗
PubMed1992

[A case-control study on the relationship between neonatal hyperbilirubaemia and usage of oxytocin during labour].

Analytical method for multiple exposure level data of matching (1:1) case-control study was employed in the study on the relationship between neonatal hyperbilirubinemia and usage of oxytocin (during) in labour. The result showed that there was significant association between them (chi 2 = 15.538, df = 3, P = 0.0014). The odds ratios for various exposure level were 1-5.9 (u): OR = 1.085; 6-8.9 (u): OR = 5.5; 9 + (u): OR = 3.687 and the log linear trend among them was significant (chi 2 = 11.991, df = 1, P = 0.0005).

Case-Control Studies↗
PubMed1992

Heat-shock protein induction in adriamycin and picornavirus-infected cardiocytes.

BACKGROUND: Both chemicals, such as the chemotherapy agent adriamycin, and viruses, such as the picornaviruses coxsackievirus B3 and encephalomyocarditis virus, cause metabolic injury in myocardial cells. This injury includes depression of cellular RNA and protein synthesis and production of oxygen free radicals which are known to induce increased expression of "heat-shock" or stress proteins (hsp). These hsp can stimulate potent T lymphocyte responses that may then contribute to cardiac damage associated with adriamycin therapy and picornavirus infections. EXPERIMENTAL DESIGN: To determine whether adriamycin and the picornaviruses stimulate hsp expression, cultured neonatal myocardial cells from BALB/c Cum mice were treated with heat-shock, adriamycin and either infectious or ultraviolet irradiated (noninfectious) CVB3. The treated myocardial cell homogenates were subjected to polyacrylamide gel electrophoresis and Western blot analysis for 70 kilodalton hsp. To determine whether these treatments stimulated T lymphocyte responses (presumably to hsp), BALB/c Cum mice were injected with 0.1 ml complete Freund's adjuvant containing 0.1 mg of heat-killed mycobacterium tuberculosis, 10 mg/kg adriamycin or 5 x 10(4) plaque-forming units CVB3 intraperitoneally. Splenic lymphocytes obtained 7 days later from these animals were evaluated in a 51Cr release cytotoxicity assay to cultured myocytes treated with heat-shock, adriamycin or virus. Cytolytic T lymphocytes (CTL) were characterized as to T cell subset and T cell receptor (TcR) utilization treating CTL populations with anti-CD4 or anti-CD8 antibodies or with anti-alpha/beta TcR or anti-gamma/delta TcR antibodies. RESULTS: Both adriamycin and infectious virus treatment of myocardial cells stimulated increased hsp expression. Ultraviolet irradiation of the virus prevents virus replication and failed to elicit hsp production in heart cells. Two types of CTL were detected. Animals injected with complete Freund's adjuvant virus, and adriamycin produced CD8+, gamma/delta TcR+ CTL that were not major histocompatibility complex antigen restricted since both CBA (H-2k) and BALB/c (H-2d) myocardial cells were lysed. Virus-specific CTL, belonging to the CD4+, alpha/beta TcR+ population, were detected in CVB3-infected mice. CONCLUSIONS: Different agents that metabolically injure myocardial cells can induce increased expression of one or more hsp. CTL presumably directed to these hsp can cross-reactively lyse targets treated with any of the hsp inducing agents. This observation raises the question whether multiple exposures of individuals to dramatically different hsp-inducing agents might result in increasingly damaging immune responses.

Animals↗
PubMed1959

Cerebral vascular occlusion; angiographic diagnosis.

Cerebral arterial occlusion is a fairly frequent condition. We have diagnosed nine cases by cerebroangiography in the past two years, and there are many patients not given this special examination.Precise diagnosis has become more important as advances in therapy make prognosis more hopeful. The symptoms are various according to the location and degree of occlusion and the amount of collateral circulation.Angiographic diagnosis is not difficult, but repeated demonstration of the block should be insisted on. This is best done with multiple exposures after a single injection of contrast medium. We use 7 cc. of 50 per cent Hypaque(R) and one exposure per second through the arterial, capillary and venous phases. The films should cover the entire head and neck lest an occlusion in the common carotid be overlooked. We have found the Schonander biplane apparatus very satisfactory, using films 14 inches square and exposing them in anteroposterior and lateral projections simultaneously.

Angiography↗
PubMed2004

Occupational asthma in a highly industrialized region of UK: report from a local surveillance scheme.

Estimates of the incidence of occupational asthma may be derived from surveillance schemes established in several countries. SHIELD is a voluntary surveillance scheme for occupational asthma in the West Midlands, a highly industrialized region of UK. The aim of this study was to estimate the general and specific incidence of occupational asthma in the West Midlands in 1990-97. The annual incidence was 41.2/million. There was a two fold difference in the incidence by sex (male 59.6/million/yr; female 27.4/million/yr). The highest annual incidence (53.2/million) was observed in the age group 45-64 yr (male) and 45-59 yr (female). Spray painters were the occupation at the highest risk of developing occupational asthma, followed by electroplaters, rubber and plastic workers, bakery workers and moulders. Although the percentage of reported cases was low among healthcare workers, there was a raising trend. Isocyanates still remained the most common causative agents with 190 (17.3%) out of the total 1097 cases reported to the surveillance scheme in seven years. There was a decrease in the reported cases due to colophony (9.5% to 4.6%), flour & wheat (8.9% to 4.9%). There was an increase of reported cases due to latex (0.4% to 4.9%) and glutaraldehyde (1.3% to 5.6%). The serial mesurement of peak expiratory flow at and away from work was the most used method of diagnosis to confirm the occupational cause of asthma. Specific bronchial challenge test with the occupational agents were used when the serial measurement of peak expiratory flow was not able to confirm undoubtdely the diagnostic suspicion or when it was difficult to identify the possible causative agent due to multiple exposures in the workplace. Following diagnosis, 24% of the patients were moved away from exposure within the same workplace in 1997, compared to 15.8% in the previous years. Those remaining exposed to the causative agent in the same workplace decreased from 28.3% to 17.7% between 1990-97. The surveillance of occupational asthma trough this voluntary scheme has allowed to monitor the incidence of the disease in the region and to identify clusters of cases, where control measures are a priority.

Adolescent↗
PubMedDate not supplied

Radioactive materials in biosolids: national survey, dose modeling, and publicly owned treatment works (POTW) guidance.

The Nuclear Regulatory Commission (NRC) announced the availability of three new documents concerning radioactive materials in sewage sludge and ash from publicly owned treatment works (POTW). One of the documents is a report presenting the results of a volunteer survey of sewage sludge and ash samples provided by 313 POTWs. The second document is a dose modeling document, using multiple exposure pathway modeling focused on a series of generic scenarios, to track possible exposure of POTW workers and members of the general public to radioactivity from the sewage sludge or ash. The third document is a guidance report providing recommendations on the management of radioactivity in sewage sludge and ash for POTW owners and operators. This paper explains how radioactive materials enter POTWs, provides criteria for evaluating levels of radioactive material in sludge and ash, and gives a summary of the results of the survey and dose modeling efforts.

Data Collection↗
PubMedDate not supplied

[Active and passive smoking: two sides of the same medal].

The authors underline the similarities between active and passive smoking under many features, i.e. chemical and physical composition, the kind of health risks, the anti-educational impact on the youth. The special character of passive smoking is also discussed, such as its multiplicative exposure effect on the population, and the hazard to high-risk people like children, pregnant women, and respiratory and cardiovascular patients.

Humans↗
PubMed2005

Effect of precipitation on seasonal variability in cryptosporidiosis recorded by the North West England surveillance system in 1990-1999.

The goal of this study was to examine temporal and spatial variability of reported cryptosporidiosis in 15 health authorities in the North West of England using regression modelling. We also examined the role of precipitation as a driving factor for seasonal variation. We separated the time series of the reported cryptosporidiosis into two processes: an endemic process and an epidemic process, and examined the spatial variability of each of these processes. In the North West region of England we observed a strong seasonal pattern that consists of two waves, spring and autumn, during which the weekly rates exceeded the endemic level 3.5 and 3 times, respectively. Health authorities with the high endemic cryptosporidiosis incidence and well-pronounced seasonal patterns exhibited a significant increase in rates of cryptosporidiosis associated with increased precipitation. The endemic level and the magnitude of epidemic peaks were inversely related, which might be indicative of multiple exposures to the pathogen in these localities and the development of some partial immunity.

Animals↗
PubMed2005

Magnesium in drinking water and cardio-vascular disease--an epidemiological dilemma.

The relation between drinking water and cardiovascular disease has been evaluated in a number of studies. Certain of these show strong relationships whereas others do not. This review analyses the methodological aspects on epidemiological studies in terms of dose-range, confounding factors and multiple exposures. It is concluded that there is good evidence for a relation between drinking water quality and cardio-vascular disease, that several methodological criteria for such studies need to be considered, that there is little evidence for magnesium as the single causative agent, and that the relevant exposure should be considered as a mixture of minerals.

Cardiovascular Diseases↗
PubMed2006

Programmable CSF shunt valve: in vitro assessment of MR imaging safety at 3T.

A programmable CSF shunt valve was assessed for magnetic field interactions, heating (transmit-receive body radio-frequency coil; whole-body averaged specific absorption rate, 2.1 W/kg), functional alterations, and artifacts at 3T. The programmable valve showed minor magnetic field interactions and heating was not excessive (+0.8 degrees C). The function of the programmable valve was not altered by multiple exposures to the 3T scanner or from exposure to various MR imaging conditions. Therefore, this implant is safe for a patient undergoing MR imaging at 3T or less when the radiologist follows specific safety guidelines. Artifacts for the programmable valve were relatively large in relation to the size and shape of the valve; this finding may impact the diagnostic use of MR imaging if the area of interest is in proximity to this implant.

Cerebrospinal Fluid Shunts↗
PubMed1991

High prevalence of hepatitis C virus antibodies in a local haemophiliac population.

Non-A, non-B hepatitis is common among individuals with clotting factor deficiencies who have had multiple exposures to replacement concentrate. Newly introduced screening tests for hepatitis C virus antibody make it possible to determine the prevalence of this entity in defined populations. In 68 haemophiliac patients attending the Groote Schuur Hospital clinic, 44 were shown to be positive (65%). There was no significant correlation between seropositivity for this agent and severity of the bleeding disorder, age or elevation of the liver enzyme values.

Adolescent↗
PubMed2006

[Effects of different immunodepressants on the sperm parameters of kidney transplant recipients].

OBJECTIVE: To study the effects of different immunodepressants on the sperm parameters of kidney transplant recipients. METHODS: In 15 healthy fertile men and 37 kidney transplant recipients, ejaculates were aseptically obtained by masturbation. Thirty-seven patients were divided into two groups, 20 patients were treated with Prograf (FK506) combination with mycophenolate mofetil (MMF) and prednisone; 17 patients were treated with cyclosporine (CsA) combination with azathioprine with prednisone. The sperm viability, mobility parameters such as prorsad percentage motility, straight line velocity (VSL), curve line velocity (VCL), velocity of average path (VAP) and morph were estimated with a computer-assisted sperm analyzer (CASA) provided with a multiple-exposure photography system. RESULTS: There were no significant difference in sperm viability rate [(81.7 +/- 5.7)%, (79.4 +/- 6.8)% and (83.8 +/- 6.0)%], VCL [(24.1 +/- 8.6)%, (23.9 +/- 4.4)%, (24.8 +/- 4.2)% ] and VAP [(19.7 +/- 6.6)%, (18.6 +/- 2.9)%, (21.0 +/- 4.0)%] among groups of FK506, CsA and control, respectively (P > 0.05). The rate of anomaly [(67.8 +/- 5.7)%], the prorsad percentage motility [(46.4 +/- 8.1)%] and VSL [(15.4 +/- 4.6)%] in the group of FK506 were respectively significantly lower and higher than those in the group of CsA [(80.1 +/- 5.6%, (33.3 +/- 6.4)%, (10.2 +/- 2.4)%] (P < 0.05). CONCLUSION: The application of FK506 combined with MMF could help recover the mobility and morphology of the sperm in kidney transplantation recipients.

Adolescent↗
PubMedDate not supplied

Occupational asthma.

Occupational asthma (OA) is one of the most common forms of occupational lung disease in many industrialized countries, having been implicated in 9 to 15% of adult-onset asthma. Work-related asthma includes: 1. immunologic OA, characterized by a latency period before the onset of symptoms; 2. nonimmunologic OA, which occurs after single or multiple exposures to high concentrations of irritants; 3. work-aggravated asthma, which is pre-existing or concurrent asthma exacerbated by workplace exposures; and 4. variant syndromes. OA is important to recognize clinically, because it has serious medical and socioeconomic consequences. Diagnosis of OA should be confirmed by objective testing early after its onset. Removal of the worker from exposure to the causal agent and early treatment with anti-inflammatory drugs lead to a better outcome. Assessment of the work environment and identification of host factors may provide us with useful information about the mechanisms involved in OA. Another issue concerns strategies for preventing OA which should be implemented.

Allergens↗
PubMed1991

T cell epitopes of the circumsporozoite protein of Plasmodium vivax. Recognition by lymphocytes of a sporozoite-immunized chimpanzee.

The humoral and cellular antisporozoite immune responses of a laboratory-born chimpanzee were measured following multiple exposures to the bites of Plasmodium vivax-infected mosquitoes. T cell lines and clones derived from the chimpanzee's PBL were used to identify T cell epitopes of the P. vivax circumsporozoite (CS) protein. Two independently obtained cell lines, established by culturing the PBL with either a recombinant P. vivax circumsporozoite (rPvCS) protein or a pool of synthetic peptides spanning the rPvCS sequence, recognized a 20-mer peptide from a nonpolymorphic region of the carboxyl terminus of the CS protein. This peptide overlaps a sequence homologous to region II of the Plasmodium falciparum CS protein. A third T cell line recognized an epitope within the central repeat domain, which has recently been found to be a polymorphic region of the P. vivax CS protein. The CD4+ clones derived from this third T cell line secreted IFN-gamma and IL-2 when stimulated with either the P. vivax repeat peptide (DRAAGQPAG)2 or the rPvCS protein.

Amino Acid Sequence↗
PubMed2006

Squat-stand test response following 10 consecutive episodes of head-up tilt.

INTRODUCTION: The cardiovascular system is adaptable to multiple exposures to gravity over several days, and to repeated exposures in a single day. This study aimed to investigate if the cardiovascular adaptation observed following 10 +75 degrees head-up tilts (HUT) would improve the responses to the squat-stand test (SST). METHODS: There were 16 subjects who were randomly allocated into either a tilting group that underwent 10 +75 degrees HUTs in 70 min (Tilting) or a control group that underwent 70 min of rest (Control). Before and after HUT or rest, subjects performed a SST (SST1 and SST2, respectively). Heart rate (HR), BP [systolic (SBP), diastolic (DBP), mean (MAP)], total peripheral resistance (TPR), stroke volume (SV), and cardiac output (CO) were determined during both SSTs. The final 30 s of squat and the first 30 s of stand (divided into three 10-s blocks termed Stand10, Stand20, and Stand30) were compared between SST1 and SST2. RESULTS: In the Tilting condition, during the squat phase of SST2, the following were significantly elevated: SBP (131 +/- 9 to 140 +/- 7.2 mmHg) and MAP (94 +/- 8.7 to 105 +/- 10.2 mmHg); DBP (76 +/- 9.4 to 87 +/- 11.9 mmHg); TPR (1197 +/- 524.6 to 229 +/- 610.5 dyn x s(-1) x cm(-5)) and HR were significantly decreased (78 +/- 6.9 to 73 +/- 7.5 bpm) compared with SST1. At Stand10, DBP and MAP were significantly increased (59 +/- 9.5 to 69 +/- 15.7 mmHg and 74 +/- 8.9 to 84 +/- 14.7 mmHg, respectively); at Stand20, SBP was increased (121 +/- 17 to 128 +/- 22 mmHg); and at Stand30 the following were increased: DBP (64 +/- 8.8 to 75 +/- 16.1 mmHg); SBP (127 +/- 9.2 to 139 +/- 15.8 mmHg); and MAP (79 +/- 8 to 90 +/- 14.9 mmHg). There were no differences observed between SST1 and SST2 in the Control group. DISCUSSION: Cardiovascular responses to the SST can be improved with 10 consecutive +75 degrees HUTs. This is predominantly due to an increase in DBP, indicative of a change in vascular resistance.

Adaptation, Physiological↗
PubMed1991

Cyanide-induced increases in plasma catecholamines: relationship to acute toxicity.

Cyanide is known to initiate release of catecholamines from chromaffin cells and isolated adrenals but the effect of cyanide on plasma catecholamine levels has not been reported. The present study demonstrates that cyanide produces marked elevation of plasma catecholamines in mice. A sublethal dose of KCN (5 mg/kg, sc) significantly increased plasma norepinephrine (NE) and epinephrine (EPI) at 5 min after administration, and the elevated levels returned to normal at 15 min. At a dose of 10 mg/kg, NE and EPI plasma levels remained elevated over a 15 min period. Multiple exposures to sublethal doses of KCN (5 mg/kg, sc, 4 doses at 15 min intervals) produced a steep, sustained rise in plasma NE and EPI. Administration of KCN (15.6 micrograms) directly into the lateral ventricles of the brain caused convulsions and respiratory depression, but did not affect plasma catecholamine levels. Pretreatment with pargyline did not alter the magnitude of the response to KCN. Adrenalectomy prevented the increase in plasma EPI and had no influence on plasma NE levels, indicating cyanide acts directly on the adrenals to stimulate EPI release. It is proposed that KCN directly stimulates the sympathoadrenal axis to increase plasma catecholamine levels.

Adrenal Glands↗
PubMed1991

A mathematical model for radiation-induced myelopoiesis.

A model for damage, repair, killing, and repopulation of myelopoietic marrow is presented. Evaluation produces time and dose-rate profiles during and following any complex irradiation. Equations model variable dose rates, multiple exposures, different sources, and arbitrary intervals between treatments. If factors which dominate the control of biological processes can be demonstrated, an option is to set biological rate constants to experimentally determined values. Previously, knowledge did not permit identification of dominating biological processes and their temporal rates. But a unique feature of this study is that unspecified lesions for killing and injury of cells are evaluated from mortality data on the animal species of choice. "Unspecified" is used to indicate a condition of assumption-free modeling of molecular processes, whereby rate constants for cellular effects are simply computed directly from animal mortality data. Coefficients (estimated by maximum-likelihood methods for nonspecific processes) are compared with experimental values for specific processes. The model has many uses, including modeling of the myelopoietic potential as a function of time. Another option is to calculate the whole-body survival curve for cells that control myelopoiesis as a result of the treatment schedule. Also through simple extensions of the model, an extremely complex protocol can be identified with an equivalent prompt dose value--even for partial-body, fractionated exposures.

Animals↗