Surface strains induced by measured loads on teeth in vivo: a methodological study

Visual feedback enabled three subjects to apply predetermined near-axial loads to the incisal edge of an intact maxillary central incisor. In two subjects, principal strains and orientations developed on the labial surface of the intact incisor were resolved from strains recorded with a multiple element strain gauge. Load application was accurate and precise enough to allow resolution of strains induced by target loads of 10 to 50 N. Axially orientated compressive labial surface strains were induced by measured loads. The method could be used to validate bench-top stress analyses and investigate the effects of restoration on the structural integrity of teeth.     

Timing of supplementation of selenium and isoflavones determines prostate cancer risk factor reduction in rats

Drug-drug interactions have become an important issue in health care. It is now realized that many drug-drug interactions can be explained by alterations in the metabolic enzymes that are present in the liver and other extra-hepatic tissues. Many of the major pharmacokinetic interactions between drugs are due to hepatic cytochrome P450 (P450 or CYP) enzymes being affected by previous administration of other drugs. After coadministration, some drugs act as potent enzyme inducers, whereas others are inhibitors. However, reports of enzyme inhibition are very much more common. Understanding these mechanisms of enzyme inhibition or induction is extremely important in order to give appropriate multiple-drug therapies. In future, it may help to identify individuals at greatest risk of drug interactions and adverse events.     

Effect of soy protein-rich diet on renal function in young adults with insulin-dependent diabetes mellitus

BACKGROUND: Diabetic nephropathy is the most frequent cause of end-stage renal disease in the Western world. Dietary intake, including protein amount and type, seems to affect the progression of renal disease. This pilot study tested the hypothesis that substituting soy protein for animal protein in the diets of diabetics would help correct glomerular hyperfiltration. METHODS: Twelve young adults (aged 29.9 +/- 2.4 years) with type 1 diabetes mellitus (duration of diabetes 15.1 +/- 2.3 years) and hyperfiltration (glomerular filtration rate, GFR > 120 ml/min/1.73 m2) completed a crossover, dietary intervention trial. After a four-week assessment of baseline characteristics and dietary habits, subjects were assigned to either a control or soy diet for eight weeks after which each subject was crossed over to the alternative diet for another eight-week period. RESULTS: Mean GFR was significantly reduced (p < 0.02) after eight weeks on the soy diet (143 +/- 7.4 ml/min/1.73 m2) compared with baseline (159 +/- 7.7 ml/min/ 1.73 m2) and control diets (161 +/- 10.0 ml/min/1.73 m2). Urinary excretion of the soy isoflavones was significantly higher (p < 0.01) at the end of the soy diet (genistein 1,014.6 +/- 274.1 nmol/h, daidzein 2,645.1 +/- 989.6 nmol/h) compared with baseline (genistein 53.7 +/- 31.1 nmol/h, daidzein 151.1 +/- 74.1 nmol/h) and control diets (genistein 41.1 +/- 13.3 nmol/h, daidzein 127.5 +/- 54.0 nmol/h). The soy diet significantly reduced total and LDL cholesterol by 7% and 9%, respectively. CONCLUSIONS: Implementation of a soy-based diet appears to reduce the GFR and total and LDL cholesterol of young adults with type 1 diabetes and glomerular hyperfiltration, thus affecting positively their clinical profile.     

Unusual germ cell organization in the seminiferous epithelium of a murid rodent from southern Asia, the greater bandicoot rat, Bandicota Indica

In the greater bandicoot rat, Bandicota indica, of south-east Asia, nine cell associations were documented in the testicular seminiferous epithelium. In about 10% of the tubule cross sections two or more cell associations occurred and, furthermore, some of the generations of germ cells within the cell associations were sometimes either out of phase, or missing, in the tubule cross sections. These features, together with the fact that this species has a highly pleiomorphic sperm head shape, are somewhat reminiscent of those of the seminiferous epithelium in humans and some other primates but not of common laboratory rodents. This species could thus be a good model for investigating irregular patterns of spermatogenesis in naturally occurring wild species of rodent.     

Phytoestrogens: hormonal action and brain plasticity

Because of their protective effects in age-related diseases and hormone-dependent cancers, the use of phytoestrogens (isoflavones) as 'natural' remedies has gained prominence. Isoflavones are estrogen mimics that bind estrogen receptors and act like natural selective estrogen receptors modulators. However, limited data exists regarding the influence of soy-derived dietary isoflavones in brain. This brief review will address these topics and examine the influence of dietary isoflavones on sexually dimorphic hypothalamic nuclei. We have observed that altering the isoflavone content within diet significantly affects both the sexually dimorphic nucleus of the preoptic area (a structure that is larger in males than in females) and the anteroventral periventricular nucleus (a structure that is larger in females than in males). Specifically, when animals were switched from phytoestrogen-rich to a phytoestrogen-free diet the volume of the sexually dimorphic nucleus of the preoptic area was decreased in males (no alterations were detected in females). Conversely, when the anteroventral periventricular nucleus was examined, volume changes were recorded in males and females opposite to the patterns observed for the sexually dimorphic nucleus of the preoptic area. Given the practical limitations of examining the effects of dietary phytoestrogens in the human brain, it is important to establish comparative data sets to elucidate phytoestrogen's hormone action and potentially its beneficial brain health effects.     

Prevalence of and factors affecting postpreparation pain in patients undergoing two-visit root canal treatment

AIM: This longitudinal, prospective study (i) investigated the prevalence of postpreparation pain during root canal treatment and (ii) evaluated the influence of factors affecting the pain experience. METHODOLOGY: Twenty practitioners, comprising general dental practitioners, MSc graduates and endodontists, participated in this study. The patient sample (n=272) was derived from consecutive patients attending the practitioners' surgeries for a two-visit root canal treatment on a single tooth. Demographic, medical history, preoperative and intraoperative data as well as pain experience on days 1 and 2 after root canal preparation were recorded. Intensity of pain experienced was recorded on a visual analogue scale (VAS) of 0-5. The data were analysed using logistic regression models. RESULTS: The prevalence of postpreparation pain within 48 h after treatment was 64.7% (n=176), but less than 10% of patients experienced severe pain (VAS 4 or 5) on either day 1 or day 2. The presence of preoperative pain (OR=2.841, P<0.001), tooth type (OR=2.008, P=0.009), systemic steroid therapy for other medical reasons (OR=0.181, P=0.023) and preoperative swelling (OR=2.433, P=0.040) were the only factors to significantly influence postpreparation pain experience. CONCLUSIONS: The prevalence of postpreparation pain was high, and the important prognostic determinants were presence of preoperative pain, tooth type, systemic steroid therapy and preoperative swelling.