Numerous Investigations (numerous + investigation)

Distribution by Scientific Domains

Selected Abstracts

Tooth wear in two ancient populations of the Khazar Kaganat region in the Ukraine

W. H. Arnold
Abstract Tooth wear is a common phenomenon in archaeological material. It has been related to the abrasiveness of diet and to the tribological attrition of teeth of individuals. Numerous investigations have been carried out in north and middle American samples as well as African anthropological material. Not much is known about tooth wear in European cultures. Eleven skulls from Chervona Gusarovka, and 14 skulls from the Upper Saltov sites of the Khazar Kaganat region (8th,10th centuries AD) in eastern Ukraine, with different diets were examined. A total of 208 teeth were studied for tooth wear, caries prevalence and periodontal status. Abrasion grades were determined according to a standardised classification and statistically evaluated. Periodontal status was measured using the distance between the enamel-cementum junction and alveolar crest and the gingival attachment level respectively. Tooth wear was significantly different (P,<,0.01) between the two populations. A low caries prevalence of 4.2% in the Chervona Gusarovka population and 1.7% in the Upper Saltov population was found. Significantly more alveolar crest bone resorption on the lingual side was found in the premolars and anterior teeth of the Chervona Gusarovka population. No significant differences were found regarding gingival attachment levels and gingival recession. It is concluded that the content and mode of food preparation influenced tooth wear, as reflected by the prevalence of dental caries and periodontal diseases in these ancient populations. Copyright 2006 John Wiley & Sons, Ltd. [source]

Influence of cigarette smoking on spermatozoa via seminal plasma

ANDROLOGIA, Issue 4 2005
M. Arabi
Summary Numerous investigations have been conducted on the relationship between cigarette smoking and male infertility, however, the exact molecular mechanisms are not well understood in most of the cases. Few studies have indicated the direct effect of seminal plasma (SP) [in different dilutions with phosphate buffer solution (PBS)] from smokers (SM) on the sperm functional parameters from nonsmokers (non-SM). The aim of this study was to provide evidence that cigarette smoking affects male fertility via altering the sperm quality. Our results indicated that exposure of spermatozoa from the non-SM to the SP from the SM yielded a significant reduction in the sperm motility and acrosome reaction and an elevation in the amount of malondialdehyde (MDA), in a certain time course. Exposure of spermatozoa from the SM to the SP from the non-SM or with PBS resulted in the nonsignificant improvement in the altered sperm functional parameters indicating removal of SM's SP and then subsequent reconstitution with physiological media could be of clinical significance in the various assisted reproductive technologies applied for SM. However, the detrimental effect of SM's SP on non-SM's spermatozoa was prominent. In addition, as spermatozoa in SM's SP are susceptible to peroxidative damages, men with such cells who wish to have children should especially benefit from quitting smoking. [source]

Role of Repolarization Restitution in the Development of Coarse and Fine Atrial Fibrillation in the Isolated Canine Right Atria

Introduction: Although the role of action potential duration restitution (APD-R) in the initiation and maintenance of ventricular fibrillation (VF) has been the subject of numerous investigations, its role in the generation of atrial fibrillation (AF) is less well studied. The cellular and ionic basis for coarse versus fine AF is not well delineated. Methods and Results: We measured APD-R during acetylcholine-mediated AF as well as during pacing (standard and dynamic protocols) in crista teriminalis, pectinate muscle, superior vena cava, and appendage of isolated canine arterially perfused right atria (n = 15). Transmembrane action potential (TAP), pseudo-ECG, and isometric tension development were simultaneously recorded. Acetylcholine flattened APD-R measured by both standard and dynamic protocols, but promoted induction of AF. AF was initially coarse, converting to fine within 3,15 minutes of AF. Coarse, but not fine AF was associated with dramatic fluctuations in tension development, reflecting wide variations in intracellular calcium activity ([Ca2+]i). During coarse AF, APD-R data displayed a cloud-like distribution pattern, with a wide range of maximum APD-R slope (from 1.21 to 0.35). A maximum APD-R slope >1 was observed only in crista terminalis (3/10). The APD-R relationship was relatively linear and flat during fine AF. Reduction of [Ca2+]i was associated with fine AF whereas augmentation of [Ca2+]i with coarse AF. Conclusions: Our data indicate that while APD-R may have a limited role in the maintenance of coarse AF, it is unlikely to contribute to the maintenance of fine AF and that [Ca2+]i dynamics determine the degree to which AF is coarse or fine. [source]

The norepinephrine transporter and its regulation

Prashant Mandela
Abstract For many years, the norepinephrine transporter (NET) was considered a ,static' protein that contributed to the termination of the action of norepinephrine in the synapse of noradrenergic neurons. The concept that the NET is dynamically regulated, adjusting noradrenergic transmission by changing its function and/or expression, was considered initially in the mid 1980s. Since that time, a plethora of studies demonstrate that the NET is regulated by several intracellular and extracellular signaling molecules, and that phosphorylation of the NET is a major pathway regulating its cell surface expression and thereby its function. The NET is a target of action of a number of drugs that are used long-term therapeutically or abused chronically. This has driven numerous investigations of how the NET and its function are regulated by long-term exposure to drugs. While repeated exposure to many drugs has been shown to affect NET function and expression, the intracellular mechanisms for these effects remains elusive. [source]

Examination of mycosis fungoides for the presence of Epstein,Barr virus and human herpesvirus-6 by polymerase chain reaction

E Erkek
Abstract Background The aetiology of cutaneous T-cell lymphoma (CTCL) remains unknown despite numerous investigations. In recent years, retroviruses and human herpesviruses have been implicated to play a causal part in CTCL. Objective The aim of this study was to elucidate the possible aetiopathogenetic role of human herpesviruses (HHV) in mycosis fungoides (MF). Methods Polymerase chain reaction was used to study formalin-fixed, paraffin-embedded lesional skin biopsies from 92 subjects with MF to evidence possible presence of Epstein,Barr virus (EBV) and HHV-6. Results Biopsy specimens from nine subjects (9.8%) evidenced EBV DNA, whereas all except one of the subjects (1.1%) lacked HHV-6 DNA. Conclusions Although these findings do not support a primary aetiological role for EBV and HHV-6 in classical CTCL, the possibility remains that both viruses, particularly EBV, may act as potential cofactors in the development of CTCL. [source]

Studies of Aedes aegypti (Diptera: Culicidae) ovipositional responses to newly identified semiochemicals from conspecific eggs

Kumaran Ganesan
Abstract, The chemical factors influencing the selection of oviposition site by gravid females of various mosquito species have been the subject of numerous investigations. Recent studies have revealed this behaviour to be controlled by semiochemicals. Here we report studies on semiochemicals of egg origin and their effect on the ovipositional behaviour of Aedes aegypti. The compounds present in egg extracts of Ae. aegypti mosquitoes were isolated and identified by gas chromatography-mass spectrometry. They were then evaluated for their effect on ovipositional behaviour against gravid females of Ae. aegypti mosquitoes at different concentrations. Gravid female Ae. aegypti were found to be sensitive to all the identified compounds: 6-hexanolactone, methyl dodecanoate, dodecanoic acid, methyl tetradecanoate, tetradecanoic acid, methyl (Z)-9-hexadecenoate, methyl hexadecanoate (Z)-9-hexadecenoic acid, hexadecanoic acid, methyl (Z)-9-octadecenoate, methyl octadecanoate (Z)-9-octadecenoic acid and octadecanoic acid. Among them, dodecanoic and (Z)-9-hexadecenoic acids showed significant positive ovipositional response at different concentrations whereas all the esters showed deterrent/repellent ovipositional effect. [source]