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Major Contributory Factor (major + contributory_factor)
Selected AbstractsUltrastructural clues for the potent therapeutic effect of melatonin on aging skin in pinealectomized ratsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 6 2006Mukaddes E Abstract Recently we have reported a significant reduction in the thickness of epidermis and epidermis + dermis in the back, abdominal and thoracic skin of the long-term pinealectomized rats and the potent therapeutic effect of melatonin on the pinealectomy-induced morphometric changes. The present study was aimed to determine the fine structure of the abdominal and thoracic skin in pinealectomized rats and the effect of melatonin on skin ultrastructure. Rats were pinealectomized or sham operated (control) for 6 months. Half of the pinealectomized rats were treated with 4 mg/kg melatonin during the last month of the experiment. Pinealectomy resulted in prominent ultrastructural changes in the skin. Epidermal atrophy, disorganization and cytological atypia were obvious. Tonofilament distribution was not uniform, and intercellular space was narrow. Nuclear irregularity and heterochromatin condensation were detected. Many mitochondria were irregular and edematous with increased translucence of the matrix, either partial or total destruction of crests and frequently the presence of vacuoles, myelin figures and dense bodies. Microprojections of basal cells into the dermis were observed. The dermis was thin, and collagenous fibers were loosely arranged. The epidermis in melatonin administered pinealectomized rats was obviously thicker than that of pinealectomized rats. The cells of each layers had characteristic morphological and ultrastructural features. Nuclear irregularity and heterochromatin condensation were not seen. Mitochondria were generally normal in ultrastructural appearance but rarely vacuoles and myelin figures were observed. The dermis was thick, and collagenous fibers were closely packaged. This paper provides an additional ultrastructural evidence that the damage to mitochondria is the major contributory factor to skin aging and that melatonin has potent therapeutic effects in reducing age-related changes via protecting fine structure of the skin. [source] Lack of association between HLA genotype and chronic fatigue syndromeINTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 3 2001J. A. Underhill Summary Although the aetiology of chronic fatigue syndrome is controversial, evidence that infective agents including viruses may have a role in the development of the condition has led to studies seeking an association with the immunomodulatory HLA genes. In the present study, we sought to extend previous work using a well-characterized patient group and modern HLA genotyping techniques. Fifty-eight patients were phenotyped for HLA A and B by microcytotoxicity and genotyped for HLA DRB, DQB and DPB by PCR oligoprobing, and the frequencies of antigens so assigned were compared with those from a control group of 134. No significant differences in HLA frequencies were found between patient and control groups. Thus, this study does not confirm previous findings of an HLA association with chronic fatigue syndrome, suggesting that neither presentation of viral antigen by HLA class I nor antigen processing genes in the HLA region is a major contributory factor in the development of the disease. [source] Paediatric antibiotic prescribing by general dental practitioners in EnglandINTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 4 2001N.O.A. Palmer Objectives. The inappropriate use of antibiotics is known to be a major contributory factor to the problem of antimicrobial resistance. No information is available on how practitioners prescribe antibiotics for children. This study investigated the prescribing of liquid-based antibiotics for children by general dental practitioners in England. Design. Analysis of National Health Service liquid-based prescriptions issued by general dental practitioners in England. Sample and methods. All prescriptions issued by practitioners in 10 Health Authorities in England for February 1999 were collected. All the liquid-based antibiotic prescriptions for children were selected and we investigated the type of antibiotic prescribed, whether sugar free, the dose, frequency and duration. Results. A total of 18614 prescriptions were issued for antibiotics. Of the 1609 liquid-based paediatric prescriptions 88·3% were for generic and 11·7% for proprietary antibiotics, of which 75·5% were for amoxicillin, 15·2% for phenoxymethylpenicillin, 6·6% for erythromycin, 1·7% for metronidazole. Cephalexin, ampicillin, cephadrine and combinations of two antibiotics were also prescribed. There was a wide variation in dosages for all the antibiotics prescribed. A significant proportion of practitioners prescribed at frequencies inconsistent with manufacturers' recommendations and for prolonged periods, with some practitioners prescribing for periods up to 10 days. Only 29·1% of all the prescriptions issued were sugar free. Conclusions. The results of this study show that some practitioners prescribe liquid-based antibiotics inappropriately for children. This may contribute to the problem of antimicrobial resistance. Clear guidelines on the choice of antibiotic, dose, frequency and duration along with educational initiatives for GDPs might reverse this trend. [source] Prenatal Alcohol Exposure and Chronic Mild Stress Differentially Alter Depressive- and Anxiety-Like Behaviors in Male and Female OffspringALCOHOLISM, Issue 4 2010Kim G. C. Hellemans Background:, Fetal Alcohol Spectrum Disorder (FASD) is associated with numerous neurobehavioral alterations, as well as disabilities in a number of domains, including a high incidence of depression and anxiety disorders. Prenatal alcohol exposure (PAE) also alters hypothalamic-pituitary-adrenal (HPA) function, resulting in increased responsiveness to stressors and HPA dysregulation in adulthood. Interestingly, data suggest that pre-existing HPA abnormalities may be a major contributory factor to some forms of depression, particularly when an individual is exposed to stressors later in life. We tested the hypothesis that exposure to stressors in adulthood may unmask an increased vulnerability to depressive- and anxiety-like behaviors in PAE animals. Methods:, Male and female offspring from prenatal alcohol (PAE), pair-fed (PF), and ad libitum-fed control (C) treatment groups were tested in adulthood. Animals were exposed to 10 consecutive days of chronic mild stress (CMS), and assessed in a battery of well-validated tasks sensitive to differences in depressive- and/or anxiety-like behaviors. Results:, We report here that the combination of PAE and CMS in adulthood increases depressive- and anxiety-like behaviors in a sexually dimorphic manner. PAE males showed impaired hedonic responsivity (sucrose contrast test), locomotor hyperactivity (open field), and alterations in affiliative and nonaffiliative social behaviors (social interaction test) compared to control males. By contrast, PAE and, to a lesser extent, PF, females showed greater levels of "behavioral despair" in the forced swim test, and PAE females showed altered behavior in the final 5 minutes of the social interaction test compared to control females. Conclusions:, These data support the possibility that stress may be a mediating or contributing factor in the psychopathologies reported in FASD populations. [source] REVIEW ARTICLE: Clinical Relevance of Oxidative Stress in Male Factor Infertility: An UpdateAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2008Ashok Agarwal Male factor has been considered a major contributory factor to infertility. Along with the conventional causes for male infertility such as varicocele, cryptorchidism, infections, obstructive lesions, cystic fibrosis, trauma, and tumors, a new, yet important cause has been identified: oxidative stress. Oxidative stress (OS) is a result of the imbalance between reactive oxygen species (ROS) and antioxidants in the body, which can lead to sperm damage, deformity and eventually male infertility. This involves peroxidative damage to sperm membrane and DNA fragmentation at both nuclear and mitochondrial levels. OS has been implicated as the major etiological factor leading to sperm DNA damage. OS-induced DNA damage can lead to abnormalities in the offspring including childhood cancer and achondroplasia. In this article, we discuss the need of ROS in normal sperm physiology, the mechanism of production of ROS and its pathophysiology in relation to male reproductive system. The benefits of incorporating antioxidants in clinical and experimental settings have been enumerated. We also highlight the emerging concept of utilizing OS as a method of contraception and the potential problems associated with it. [source] A quantitative estimate of melanoma mortality from ultraviolet A sunbed use in the U.K.BRITISH JOURNAL OF DERMATOLOGY, Issue 3 2003B.L. Diffey Summary Background, Concern has been expressed for many years in the medical and regulatory literature about the adverse health effects, especially melanoma, from the use of sunbeds for cosmetic tanning. Objectives, To estimate the mortality from melanoma as a result of the use of sunbeds for cosmetic tanning in the U.K. Methods A model using a Monte Carlo random sampling technique was developed to estimate human ultraviolet exposure to both sunlight and sunbeds, and these data were used to predict the contribution of sunbeds to melanoma mortality in the U.K. Results, The mortality from melanoma due to sunbed use each year in the U.K. is estimated to be about 100 deaths. Conclusions, Sunbed use could be regarded as a relatively minor self-imposed detriment to public health compared with other voluntary ,pleasurable' activities associated with significant mortality, such as smoking and drinking alcohol. While cosmetic tanning using sunbeds should be discouraged, prohibition is not warranted especially as exposure to the sun, which cannot be regulated, remains the major contributory factor to the risk of melanoma. [source] | ||||||||||