Interfacing professional training in health maintenance and preventive medicine.

Because of emerging economic realities of the latter half of this century, the practice of preventive medicine, as opposed to curative medicine, is becoming essential in developed and developing countries. This holds true in veterinary medicine as well as in human medicine, and as we become increasingly aware of this fact, we also recognize the increasing interdependence of both fields. To determine the extent to which veterinarians are prepared to deal with this change in emphasis, two surveys have been prepared; one directed to various specialty groups within the profession and the other directed to schools of veterinary medicine. The first survey was designed to identify areas in which veterinarians felt their training had been deficient relative to decision making in applied preventive medicine. The second survey queried the schools to determine what changes had been made in their curricula to remedy these inadequacies.     

Measured Soil Water Concentrations of Cadmium and Zinc in Plant Pots and Estimated Leaching Outflows from Contaminated Soils

Soil water concentrations of cadmium and zinc were measured in plant pots with 15 contaminated soils which differed in origin, texture, pH (5.1 – 7.8) and concentrations of cadmium (0.2 – 17 mg Cd kg-¹) and zinc (36 – 1300 mg Zn kg-¹). The soil waters contained total concentrations of 0.5 to 17 µg Cd L-¹ and 9 to 3600 µg Zn L-¹, which were dominated by free metal ions as measured by an ion exchange-resin method. Annual leaching outflows were estimated from soil water concentrations to be 0.5 – 17 g Cd ha-¹ y-¹ and 9 – 3600 g Zn ha-¹ y-¹ per 100 mm of net percolation, corresponding to 0.1% per year of the total soil content of cadmium and zinc. The measured soil water concentrations of cadmium and zinc did not correlate linearly with the corresponding soil concentrations but correlated fairly well with concentrations measured in Ca(NO₃)₂ extracts of the soils and with soil water concentrations estimated from soil concentrations and pH. Such concentration estimates may be useful for estimating amounts of cadmium and zinc being leached from soils.     

A serious disease of seedling rambutan caused by Pseudocercospora nephelii sp. nov.

Pseudocercospora nephelii is described from necrotic lesions on leaves of Nephelium lappaceum seedlings in Brunei, sometimes causing complete defoliation and death. The pathogen also occurs in Sabah and Selangor in Malaysia. Recommendations for control include treatment with mancozeb or benomyl.     

Porcine leptin inhibits lipogenesis in porcine adipocytes

The present study examined whether recombinant porcine leptin alters lipid synthesis in porcine adipocytes. The stromal-vascular cell fraction of neonatal pig subcutaneous adipose tissue was isolated by collagenase digestion, filtration, and subsequent centrifugation. These cells were seeded on 25-cm2 tissue culture flasks and proliferated to confluency in 10% (vol/vol) fetal bovine serum in Dulbecco's modified Eagle medium/F12 (DMEM/F12, 50:50). Cultures were differentiated using 2.5% pig serum (vol/vol), 10 nM insulin, 100 nM hydrocortisone. After 7 d of lipid filling, cultures were washed free of this medium, incubated overnight in DMEM/F12 containing 2% pig serum (vol/vol), and then used for experiments. Acute experiments assessed U-(14)C-glucose or 1-(14)C-palmitate metabolism in cultures exposed to porcine leptin (0 to 1,000 ng/mL medium) for 4 h. Chronic experiments used cultures incubated with 0 to 1,000 ng porcine leptin/mL medium for 44 h before measurements of U-(14)C-glucose and 1-(14)C-palmitate oxidation and incorporation into lipid. Another experiment examined whether chronic leptin treatment alters insulin responsiveness by including insulin (10 nM) with incubations containing leptin. Leptin had no acute effects on glucose oxidation or conversion to lipid (P > 0.05). Acute leptin treatment decreased palmitate incorporation into lipids up to 45% (P < 0.05). Chronic leptin exposure decreased glucose oxidation (21%), total lipid synthesis (18%), and fatty acid synthesis (23%) at 100 ng/mL medium (P < 0.05). Insulin increased rates of glucose oxidation, total lipid, and fatty acid synthesis (P < 0.05); however, chronic exposure to 10 ng leptin/mL medium decreased the effectiveness of 10 nM insulin to affect these measures of glucose metabolism by approximately 18 to 46% (P < 0.05). Higher concentrations of leptin inhibited all effects of insulin on glucose metabolism (P < 0.05). Chronic exposure to leptin increased palmitate oxidation by 36% (P < 0.05). Chronic leptin exposure decreased palmitate incorporation into total lipids by 40% at 100 ng/mL medium (P < 0.05). Lipoprotein lipase activity was not affected (P > 0.05) by leptin. These data indicate that leptin functions to promote partitioning of energy away from lipid accretion within porcine adipose tissue by inhibiting glucose oxidation and lipogenesis indirectly, by decreasing insulin-mediated stimulation of lipogenesis, and by stimulating fatty acid oxidation while inhibiting fatty acid esterification.     

Relationship between aging and nutritionally controlled growth rate on heat production of heifers

The first objective of this study was to test how well a function that was developed to describe heat production (HP) in growing ewes fit HP data in growing heifers. The second objective was to determine the pattern of adaptation of HP to feed restriction and subsequent realimentation of nutrients. At 234.5 +/- 0.5 d of age, HP was determined by indirect calorimetry on 32 Meat Animal Research Center III heifers. Following the first calorimetry measurement, heifers on the High-High (HH) treatment continued to receive ad libitum access to feed, and daily feed offered to the Low-High (LH) heifers was set at 157 Mcal of ME/kg of BW0.75. Feed restriction of LH heifers continued for 84 d. After 84 d of restriction, LH heifers were allowed ad libitum access to feed. Heat production was determined 4 and 11 wk following feed restriction and 2, 5, 12, and 18 wk following realimentation. There was no residual bias when HP in ad libitum-fed heifers was estimated with an equation form developed in growing ewes: [(kcal/d) = f(BW, matBW) = BW (Ae[k(BW/mature BW)])], nor was there a residual bias when HP was predicted with an allometric equation: [(kcal/d) = f(BW) = A(BWk)]. However, there were residual biases when HP was estimated with an allometric equation that set the exponent to 0.75. Heat production per unit of BW of LH heifers was lower than that of HH heifers at 4 wk of feed restriction (P < 0.001), but HP did not differ between treatments at 11 wk of feed restriction (P = 0.87). At 2 (P = 0.002) and 5 wk (P < 0.001) following the increase in feed offered, HP per unit of BW of the LH heifers was greater than that of the HH heifers. Heat production did not differ between treatments at 12 and 18 wk following refeeding (P < 0.17). Our findings demonstrate that the relationship between HP and BW is described equally well by a logistic and allometric function, but applying a generalized interspecies exponent in an allometric equation to growing heifers results in a bias in estimating HP. The equation form developed in ewes can be used to develop a single equation for the prediction of HP across ages in heifers.