The AIN-76A defined rodent diet accelerates the development of heart failure in SHHF rats: a cautionary note on its use in cardiac studies.

Previous studies from our laboratory have shown positive benefits of linoleic acid (LA) feeding for attenuation of rat heart failure (HF). However, another research group concluded LA feeding was detrimental to cardiac function, using the American Institute of Nutrition 76A (AIN) diet as a background diet for the experimental animals only. To reconcile these conflicting results and determine whether (i) AIN has effects on cardiovascular function, and (ii) AIN reverses the positive effects of LA feeding, studies were performed using spontaneously hypertensive heart failure (SHHF) rats in both a survival study with lifetime feeding of AIN (control: Purina 5001) and a 2 × 2 factorial design for 6 weeks in young male SHHF rats with background diet and LA as variables. During a lifetime of AIN feeding, mortality from heart failure is significantly accelerated, cardiolipin altered and triglycerides increased. In young rats, 6 weeks on the AIN diet promoted increased systolic and diastolic blood pressure, increased fed and fasting blood glucose, increased serum inflammatory eicosanoids, decreased docosahexanoic acid, increased posterior wall thickness in diastole and an altered cardiolipin subspecies profile. The addition of LA to the AIN diet was able to rescue blood pressure. However, the combination increased retroperitoneal fat mass, body weight and fed blood glucose beyond the levels with the AIN diet alone. Because the AIN diet has wide ranging effects on cardiovascular parameters, our results suggest that it should not be used in animal studies involving the cardiovascular system unless induction of cardiac dysfunction is the desired outcome.

Effects of chronic nanoparticulate silver exposure to adult and juvenile sheepshead minnows (Cyprinodon variegatus).

The use of nanoparticulate silver (AgNP) is increasingly widespread and recently has been shown to have a plausible release route into aquatic environments. To date, relatively little research has examined the effects of AgNP on estuarine fish. The authors present data indicating that chronic exposure to low levels of AgNP induces significant adverse effects in both juvenile and adult sheepshead minnows (Cyprinodon variegarus; SHMs). Chronic exposure to low levels of AgNP produced significant increases in tissue burdens in both juvenile and adult SHMs, resulting in significant thickening of epithelia gill tissue and in dramatically altered gene expression profiles. The results do not appear to be attributable to the release of silver ions through particle dissolution. The alteration in gene expression was greatest in adult gonads, but no evidence of AgNP-related dysfunction was found at the tissue level. In contrast, the authors found a significant effect on gill morphology, but very little evidence of effect on gill transcription profiles.

Urinary calcium in perimenopausal women: normative values.

Twenty-four hour urinary calcium was measured under controlled dietary and metabolic balance conditions in 191 normal perimenopausal women at 5-year intervals, under varying conditions of estrogen status and dietary calcium intake, generating 586 values overall. Upper and lower limits of the normal range for urinary calcium excretion are presented for the estrogen-replete and estrogen-deprived states and for varying levels of calcium intake.

Bone dimensional change with age: interactions of genetic, hormonal, and body size variables.

Changes in bony dimensions with age were assessed longitudinally from standardized X-ray films in 170 middle-aged Caucasian women, starting at age 40 years and with a median duration of observation of 21.125 years. Consistent with earlier work, cortical area of the metacarpals and radial shaft declined with age at rates ranging from 0.57 to 0.86%/year. As predicted, estrogen replacement therapy decreased this loss in a dose-dependent manner. Not previously reported is the fact that weight gain over the period of observation reduced upper extremity bone loss. Moreover, this protection was independent of the estrogen effect. In contrast with bone loss in the upper extremity, both femur shaft diameter and femur shaft cortical area increased significantly with age (0.23 and 0.26%/year, respectively). Estrogen replacement therapy inhibited femur shaft expansion but had no effect on femur cortical area. Weight change, however, strongly influenced gain (or loss) of femur cortical area: those in the highest weight change tertile gained 4 times as much cortical area as those in the lowest weight change tertile. VDR genotype also significantly influenced femoral shaft changes: women with the bb genotype had both greater shaft expansion and a greater increase in cortical area. The VDR effects were independent of the effects of weight change and estrogen. Femoral shaft expansion was of sufficient magnitude to suggest that the mechanical properties of the entire femur may change appreciably with age. Finally, contrary to widespread belief, there was significant, if modest, expansion at the femoral neck with age.

Cognitive styles and personality characteristics strongly influence the decision to have photorefractive keratectomy.

BACKGROUND: A substantial number of patients who elect to undergo photorefractive keratectomy do so without the motivation of occupational uncorrected vision requirements. We hypothesized that information processing preferences for the auditory (versus visual) modality in a global, associative (versus detailed, sensory-oriented) style with adaptability and risk-taking (versus predictability) personality characteristics would predominate in patients electing photorefractive keratectomy. METHOD: Seventy-three prospective photorefractive keratectomy patients attended informational sessions. Sixteen occupationally driven patients and one refusal were excluded from the analysis. The 27 patients electing to proceed with surgery were compared with the 29 declining surgery. Personality characteristics and cognitive styles were determined by the Myers-Briggs Type Indicator: Abbreviated Version and the Modality Strengths Indicator. RESULTS: Subjects electing surgery showed significantly greater preferences for processing information in the auditory modality and in a global, associative style, with adaptability and risk-taking personality characteristics. Combining the attributes statistically differentiated the two groups. CONCLUSIONS: Specific cognitive styles and personality characteristics strongly influence the choice to pursue photorefractive keratectomy when that choice is not occupationally driven.

Fracture risk as determined by prospective and retrospective study designs.

Both retrospectively and prospectively designed studies consistently show low bone mass and/or bone mineral content (BMC) to be risk factor for low-trauma fractures in postmenopausal women. Along with the reports of such studies there has been concern expressed that BMC measurements overlap between fracture groups, i.e., some women with high BMC develop fractures and some women with low BMC do not. In these commonly used epidemiologic study designs, BMC does not discriminate between those who have and have not experienced the untoward event at some level of the exposure factor. The ability to discriminate is more properly determined by the sensitivity and specificity of the measured value. To contrast the concepts of risk and sensitivity, a nested case-control study was conducted within a 24-year cohort study of women at risk for osteoporosis. We found that for each 1.0 decrement of BMC z-scores, the adjusted relative risk for the prospective study design was 1.67, while the odds ratio obtained from the most recent BMC z-score measurements was 1.87. A receiver operating characteristic (ROC) curve, calculated from the nested case-control study data, showed that BMC z-scores, measured after low-trauma fracture, have both low sensitivity and low specificity to detect existing fracture status.

Studies on a 3beta-hydroxysteroid sulphotransferase from rat liver.

A steroid sulphotransferase (EC 2.8.2.2) was partially purified from female rat liver. The enzyme was active towards the substrates, dehydroepiandrosterone, epiandrosterone and pregnenolone but was inactive towards oestrogens, cholesterol and ergocalciferol. A pH optimum of 5.0 was recorded but the enzyme was unstable at low pH. The enzyme was stimulated slightly by the addition of reducing agents and inhibited by p-chloromercuribenzoate and HgCl2. Crude enzyme activity was markedly stimulated by divalent cations but this effect was not observed with purified enzyme. A Km of 13 muM was calculated for the donor substrate 3'-phosphoadenylyl sulphate and the acceptor substrate, dehydroepiandrosterone had a Km value of 6 muM. The enzyme appeared to be highly susceptible to product inhibition by adenosine 3', 5'-diphosphate.