Responses of Dairy Cows to Exogenous Bovine Growth Hormone Administered During Early Lactation

Bovine growth hormone was administered to eight Holstein cows during two 10-d periods (commencing 20 and 60 d postpartum). Treatments involved daily subcutaneous injection of excipient (control) or of 50 IU growth hormone. Feed intake and yields of milk and milk components were measured during the last 5 d of treatment. In the first injection period, milk yield of treated cows was 6% greater than that of controls (36.2 kg/d). Fat content of milk was increased by treatment with the result that fat yield was elevated by 25%. Protein content was not altered. In the second period, milk yield increased by 12%, but composition of milk was not changed. As a result, milk energy secretion was increased by a similar amount in each treatment period (4.4 versus 4.5 Mcal/d). Feed intake was not changed in either period. During early lactation the ability of cows to increase milk yield in response to exogenous growth hormone may be limited by the supply of glucose for lactose synthesis rather than by ability to mobilize body reserves in support of lactation.     

Effect of dose of bovine growth hormone on lactation of dairy cows

We administered bovine growth hormone to six Holstein cows in a Latin square design to study the relationship between dose of growth hormone and response of milk yield. Treatments were 0, 5, 10, 25, 50, and 100 IU/day of pituitary-derived bovine growth hormone administered in once-daily subcutaneous injections. Feed intake and yield of milk and milk components were measured for the last 5 days of each 10-day injection period. Yields of milk, protein, and fat increased in a dose-responsive fashion up to 32, 27, and 46% (for the 100 IU treatment) above control (26.7, .90, and .98 kg/day). Concentration of lactose in milk was not influenced by treatment, but at larger doses of growth hormone, milk fat percent was elevated and protein percent declined. As a result, milk energy secretion in response to 100 IU/day was increased 37% from control (19.2 Mcal/day). Both energy and nitrogen balance decreased with increasing growth hormone. Limited blood samples (timed to coincide with peak concentration of growth hormone postinjection) indicated treatment did not affect concentrations of glucose or insulin in blood plasma but increased concentration of growth hormone. Concentration of nonesterified fatty acids in blood plasma was increased slightly only at the 100 IU/day dose for which energy balance was negative.     

Pharmacologic profile of survivors of acute myocardial infarction at United States academic hospitals

Optimal drug therapy for patients with acute myocardial infarction (AMI) is well described in the medical literature. However, data on the actual pharmacologic management of patients surviving AMI at academic hospitals is unavailable. The purpose of this study was to document treatment profiles in 500 patients surviving AMI at 12 academic hospitals in the United States. These profiles were compared with established guidelines and were evaluated for trends. Overall, thrombolytics (streptokinase > or = tissue-type plasminogen activator) were administered in 29% of the patients, with a greater proportion of patients receiving beta-blockers than calcium channel antagonists in the initial 72 hours (61% vs 40%; p < 0.005) and at discharge (51% vs 35%; p < 0.005). Further, women were less likely than men to receive thrombolytic therapy (odds ratio [OR] = 0.61; confidence interval [CI], 0.54 to 0.69) or beta-blocker therapy within the first 72 hours (OR = 0.61; CI, 0.55 to 0.67) or at hospital discharge (OR = 0.53; CI, 0.48 to 0.58). Overall, improvements could still be made in the number of patients who receive thrombolytic and acute and chronic beta-blocker therapies after AMI, particularly in women. Changes in treatment profiles may be a reflection of the publication of large clinical trials.     

Incorporation of surface-modified UHMWPE powders and fibers in tough polyurethane composites

Ultrahigh molecular weight polyethylene (UHMWPE) powder (60 micron diameter) and chopped fiber (6.5 mm length) were surface treated with a blend of reactive gases (fluorine and oxygen.) These powders and fibers were then compounded into a thermoset polyurethane matrix. Surface-treated and control reinforcements are compared at a 10 vol.% loading level. Tensile testing indicates improved stress transfer with surface treatment. Stress transfer is also improved with fibers versus powders. Fracture toughness is characterized by measuring the essential work of fracture, w_e. Surface-treated fiber composites exhibit work of fracture values almost three times the unfilled polyurethane values. Abrasion resistance was also measured. Surface treatment was found to significantly lower wear rates of powder composites. Fiber composites had lower wear rates than powder composites, although surface treatment had little effect. An approximate inverse relationship was found between wear rate and essential work of fracture.     

Effects of feed intake and sodium bicarbonate on milk production and concentrations of hormones and metabolites in plasma of cows

Eight Holstein cows were used to investigate the effects of DM intake and sodium bicarbonate on lactational performance and concentrations of hormones and metabolites in plasma. Cows were fed a diet with or without 1.0% sodium bicarbonate (dry matter basis) in a switchback design. Four cows were fed ad libitum and four cows were fed approximately 80% of their recommended nutrient requirements by restriction of DM intake throughout the three 21-d periods. Supplementing the diet with sodium bicarbonate increased DM intake of cows fed ad libitum. There was a feed intake by sodium bicarbonate interaction for production of 4% FCM. This interaction may be explained by the difference in DM intake of cows fed ad libitum or restricted amounts of feed and supplemented with sodium bicarbonate. Cows fed restricted amounts of feed had lower milk, milk fat, milk protein, milk SNF, and milk energy yields. Restriction of feed intake increased plasma concentrations of somatotropin and nonesterified fatty acids but decreased concentrations of insulin, triidothyronine, thyroxine, glucagon, and prolactin. In contrast, feeding supplemental sodium bicarbonate did not affect concentrations of hormones or metabolites in plasma at either feed intake.     

Surface potential measurements of Langmuir films of azo dye/liquid crystal mixtures

Two-component films of a non-amphiphilic azo dye and a liquid crystal with strongly polar –CN group were studied at an air–water interface on the basis of the surface potential–mean molecular area dependence recorded simultaneously with the surface pressure–mean molecular area isotherm. Additionally, the morphology of the films was monitored with the aid of Brewster angle microscope. A conventional Langmuir technique was used to form dye/liquid crystal films during reduction and expansion of an area occupied by the molecules. From the surface potential value, the effective dipole moment in the first monolayer formed on the water was calculated. Moreover, the number of molecules with dipole moments directed from the water to the air with respect to those directed towards water was estimated. The influence of the two components' miscibilities upon the surface potential after addition of the dye to the liquid crystal was determined.     

Intramammary infusion of insulin or long R3 insulin-like growth factor-I did not increase milk protein yield in dairy cows

Two experiments investigated the regulation of milk protein synthesis in well-fed cows (n = 4) using 1) a hyperinsulinemic-euglycemic clamp and 2) intramammary infusion of insulin or long R3 insulin-like growth factor-I plus supplementary amino acids. In experiment 1, insulin was infused at 1.0 microg x kg BW(-1) x h(-1) to increase circulating levels fourfold, and euglycemia was maintained by infusion of glucose. An insulin clamp increased the yields of casein and whey protein both with and without supplementary amino acids. Plasma concentrations of insulin-like growth factor-I were increased and insulin-like growth factor binding protein-2 decreased during insulin clamp, while both insulin and insulin-like growth factor-I in milk were elevated by this treatment. Milk concentrations of insulin peaked on day 4, but insulin-like growth factor-I concentrations in milk peaked on day 1 of the insulin clamp. In experiment 2, intramammary infusion of insulin had no effects on any measured variables, while yields of milk, protein, and fat were slightly lower following long R3 insulin-like growth factor-I treatment. This could be associated with an increase in somatic cell count, which occurred following long R3 insulin-like growth factor-I treatment. Results from experiment 1 suggest insulin and insulin-like growth factor-I are likely candidates responsible for the increased milk protein yields during the insulin clamp. However, in experiment 2 neither hormone enhanced milk protein yield when administered using an intramammary technique.     

Effect of somatotropin, insulin, and glucocorticoid on lipolysis in chronic cultures of adipose tissue from lactating cows

In vitro effects of bovine somatotropin (bST) and insulin plus dexamethasone on lipolysis were evaluated using chronic cultures (48 h) of adipose tissue from lactating cows. Treatments were control (culture medium alone), bST (100 ng/ml), insulin (100 ng/ml) plus dexamethasome (10 nM), and insulin plus dexamethasone plus bST. Following the 48-h cultures, rates of lipolysis were measured in 3-h incubations with isoproterenol (10 microM), adenosine deaminase (0.75 U/ml), and various concentrations of a nonhydrolyzable adenosine analog. The addition of bST to cultures did not alter basal or isoproterenol-stimulated lipolysis. However, the ability of adenosine to inhibit rates of lipolysis was reduced by bST. When measured in the presence of maximal concentrations of adenosine analog, isoproterenol caused an increase in lipolysis above basal, which was twofold greater for explants cultured with insulin plus dexamethasone plus bST than for explants cultured with insulin plus dexamethasone. Dose-response curves for adenosine inhibition of isoproterenol-stimulated lipolysis demonstrated that chronic culture with bST decreased adipose tissue responsiveness and sensitivity to adenosine. Overall, results demonstrated that an in vitro chronic culture system can be used to examine factors that regulate lipolysis. The addition of insulin plus dexamethasone to chronic cultures better maintained the intracellular signaling system, including sensitivity and responsiveness to adenosine inhibition of lipolysis. Results also confirm that bST alters the antilipolytic response to adenosine. Thus, bST effects are in large part due to a relief in the tonic inhibition of lipolysis via changes in the inhibitory G-protein signaling system.