Substrates and inhibitors of hepatic amine oxidase inhibit dimethylnitrosamine-induced mutagenesis in Salmonella typhimurium

The mutagenic effect of dimethylnitrosamine in Salmonella typhimurium TA100, in the presence of a rat-liver homogenate derived from animals treated with Aroclor 1254, was inhibited by substrates and inhibitors of monoamine oxidase. Substrates of diamine oxidase did not inhibit dimethylnitrosamine mutagenesis and, furthermore, monoamine oxidase inhibitors had no effects on mutagenesis by benzo[a]pyrene or aflatoxin B₁. The results suggest that monoamine oxidase participates in the activation of dimethylnitrosamine to a mustagen.     

Effects of subchronic steroid therapy on vitamin E-deficient rats (38480).

Experiments were carried out to determine the effectiveness of steroid therapy in vitamin E-deficiency, as measured by autohemolysis of isolated RBC's body weight gain, serum creatine phosphokinase activity, and stabilization or labilization of isolated hepatic lysosomes. Results of such experiments would indicate whether triamcinolone acetonide could supplant vitamin E in vitamin E-deficiency states via its ability to stablize various membranes. Autohemolysis induced by vitamin E-deficiency could not be prevented by daily administration of triamcinolone. Daily dosages of 0.1 and 0.4 mg/kg (ip) triamcinolone given concomitantly with replacement vitamin E (at sufficient dosages to reverse the autohemolysis) resulted in an increased autohemolysis. No changes in lysosomal membrane fragility were noted when hepatic lysosomes were obtained from vitamin E-deficient rats with triamcinolone resulted in a greater attenuation of body-weight gain. Creatine phosphokinase levels were not augmented in vitamin E-deficient rats. Vitamin E-deficient rats supplemented with vitamin E and treated with triamcinolone, manifested an increase in creatine, phosphokinase. It was therefore concluded that although triamcinolone and vitamin E possess a common ability to stablize membranes and proteins, their mechanisms must be different since triamcinolone could not substitute for vitamin E in a deficiency state. Indeed, triamcinolone was found to be more toxic in the absence of vitamin E.     

Current "corrected" calcium concept challenged.

There is wide individual variation in the number of millimoles of calcium bound per gram of albumin in the serum. Individual regression coefficients for serum calcium concentration on serum albumin concentration have been determined in 62 people (25 of our own patients and 37 reported by others). The 95 percentile range was 0-007-0-053 mmol/g, with a median value of 0-025 mmol/g. Accordingly, it is not valid to "correct" a person''s measured serum total calcium concentration for variations in serum albumin concentration using an average regression coefficient. Rather, the individual''s own regression coefficient must be used. A tourniquet test seems to be the simplest technique for determining this value. Even then, precise interpretation of an individual''s corrected serum calcium concentration is possible only when an appropriate reference range for corrected serum calcium concentration has been established. Such an appropriate reference range must be determined from an adequate number of normal people using the individual''s own correction factor in each case.     

Amazonia trees have limited capacity to acclimate plant hydraulic properties in response to long‐term drought

The fate of tropical forests under future climate change is dependent on the capacity of their trees to adjust to drier conditions. The capacity of trees to withstand drought is likely to be determined by traits associated with their hydraulic systems. However, data on whether tropical trees can adjust hydraulic traits when experiencing drought remain rare. We measured plant hydraulic traits (e.g. hydraulic conductivity and embolism resistance) and plant hydraulic system status (e.g. leaf water potential, native embolism and safety margin) on >150 trees from 12 genera (36 species) and spanning a stem size range from 14 to 68 cm diameter at breast height at the world's only long‐running tropical forest drought experiment. Hydraulic traits showed no adjustment following 15 years of experimentally imposed moisture deficit. This failure to adjust resulted in these drought‐stressed trees experiencing significantly lower leaf water potentials, and higher, but variable, levels of native embolism in the branches. This result suggests that hydraulic damage caused by elevated levels of embolism is likely to be one of the key drivers of drought‐induced mortality following long‐term soil moisture deficit. We demonstrate that some hydraulic traits changed with tree size, however, the direction and magnitude of the change was controlled by taxonomic identity. Our results suggest that Amazonian trees, both small and large, have limited capacity to acclimate their hydraulic systems to future droughts, potentially making them more at risk of drought‐induced mortality.     

Focus: Preventive Medicine: Undiagnosed Hypertension and Undiagnosed Type 2 Diabetes among Overweight and Obese Marshallese Participants in a Diabetes Prevention Program

Hypertension and type 2 diabetes (T2D) are major public health issues that disproportionately affect minority communities, including Native Hawaiians and Pacific Islanders (NHPI). Minority communities are also more likely to have undiagnosed hypertension and T2D. Marshallese Pacific Islanders have been shown to have high proportions of diagnosed and undiagnosed hypertension and T2D. Using survey and biometric data collected from 378 overweight/obese Marshallese Pacific Islander adults, this study documents the prevalence of hypertension and T2D, as well as the prevalence of undiagnosed hypertension and T2D. The study also examines associations between undiagnosed hypertension and undiagnosed T2D and age group, sex, health care access (defined by foregone care due to cost and health insurance status), and body mass index (BMI). Among participants with blood pressure readings indicative of hypertension, 68.4% were undiagnosed, and among participants with HbA1c indicative of T2D, 31.6% were undiagnosed. A quarter of participants (24.5%) had blood pressure and HbA1c measures indicative of both undiagnosed hypertension and undiagnosed T2D. Undiagnosed hypertension was significantly associated with age group (p’s<0.0001) and sex (p=0.028). Undiagnosed T2D was significantly associated with age group (p’s<0.05), forgone care due to cost (p=0.018), health insurance status (p=0.035), and BMI (p=0.001). Participants in this study had high proportions of undiagnosed hypertension and undiagnosed T2D. These findings will be immediately useful for those working to address hypertension and T2D disparities among Marshallese and other NHPI populations.