Excretion of endogenous and exogenous purine derivatives in sheep: effect of increased concentrate intake

The scintigraphic measurement of colonic transit is currently performed using 111In ion exchange resin pellets delivered to the colon in a capsule coated with a pH sensitive polymer, methacrylate, which dissolves in the distal ileum. However, in the USA, this requires an investigational drug permit. Our aim was to evaluate the in vitro binding characteristics of activated charcoal in milieus that mimicked gastric and small intestinal content. The in vitro incubation of activated charcoal was performed with Na99Tc(m)O4, 99Tc(m)-DTPA, 111InCl3, 111In-DTPA, 201TlCl and 67Ga-citrate in the pH range 2-4 and pH 7.2 at 37 degrees C. We estimated the association of radiopharmaceuticals with the activated charcoal over a 3 h in vitro incubation. With the exception of 67Ga-citrate, the association of activated charcoal with the other radiopharmaceuticals was approximately 100% throughout the 3 h incubation. In conclusion, activated charcoal appears to adsorb avidly with common radioisotopes, and appears promising as an alternative to resin ion exchange pellets used for the measurement of gastrointestinal transit by scintigraphy.     

Use of urea by early postpartum Holstein cows

Thirty-nine lactating Holstein cows were fed high-energy complete rations ad libitum with crude protein: 1) 11.7% (negative control); 2) 13.9% (1% urea); 3) 16.6% (1% urea); or 4) 16.6% (positive control) in a continuous 12-wk study beginning at wk 5 postpartum. Milk production of 27.7, 31.8, 34.0, and 30.4 kg/day showed the use of urea nitrogen by groups 2 and probably 3. Two digestion-nitrogen balance trials with each cow also provided evidence that urea nitrogen was used for milk secretion. Energy digestibility averaged 59.4, 64.2, 65.4, and 65.8; and lower for the negative control diet. Nitrogen solubility in the diets was 28, 36, 32, and 21%, which reflects the objective of selecting ingredients with low nitrogen solubility for use in urea diets. Concentrations of ammonia nitrogen before and after feeding were 1.1, 3.3, 3.5, 4.2, and 2.2, 11.2, 11.9, and 9.3 mg/100 ml of rumen fluid. The prefeeding amounts were probably too low for maximum microbial growth. Urea-nitrogen concentrations in plasma were 8.65, 10.32, 18.00, and 17.03 mg/100 ml. These results lend support to the postulate that lactating cows in early lactation can use urea nitrogen when high-energy complete rations with ingredients of low nitrogen solubility are fed ad libitum.     

Excretion of levamisole in milk from cows treated with various formulations

The rate of disappearance of levamisole in milk from cows given levamisole hydrochloride drench, levamisole resinate in feed pellets, levamisole hydrochloride boluses, or levamisole phosphate injectable was determined. Each formulation was given as a single treatment to each of five cows at a rate equivalent to 8 mg of levamisole hydrochloride/kg of body weight. Levamisole hydrochloride residues in milk averaged .50, .55, .58, and .32 ppm at 12 hr after the administration of levamisole drench, feed, bolus, and injectable formulations. Levamisole hydrochloride residues were below .01 ppm in milk at 48 h after drench treatment and at 60 h after treatment with other three formulations. Toxicity symptoms were not observed in any cows following treatment.     

Relative activation of milk lipoprotein lipase by serum of cows fed varying amounts of fat

A routine laboratory assay to evaluate relative concentrations of lipoprotein lipase activator (apo C-II) in cow serum was developed. The assay was linear for at least 120 min after an initial, unexplained, lag ime of 13 to 15 min. Half-maximal activation was in the range of 1 to 2% serum in the assay. Inhibition of activation was indicated at high amounts (10%) of serum. Activation from plasma was half that from serum, presumably caused by an increase in substrate Km in the presence of heparin. Use of glyceryl tri[9,10-3H] oleate yielded excessively high blanks; [2-3H] glyceryl triolein is suggested for routine assay. Relative amounts of activator were not different between dry and lactating cows fed "conventional" diets. Activator concentration increased linearly with increasing dietary fat and was related to concentration of total lipid in plasma. The assay may provide a useful adjunct in studies on lipoprotein metabolism.     

Oestrous behaviour of Holstein cows during cooler and hotter tropical seasons

Seasonal effects on post-partum ovarian activity, duration and intensity of sexual behaviour were determined for Holstein dairy cattle imported from a temperate climate into a tropical region. Animals were observed continuously during the cooler (temperature-humidity index (THI) < 25) and hotter (THI > 25) seasons for 2 years. They were restricted to a cement footing in the hotter season observation period in Year 1, but had access to both concrete and dirt footing during all other seasons. Sequential milk progesterone profiles provided an indication of when follicular phases occurred, and recorded sexual behaviour was compared with these to determine if oestrous signs accompanied ovulations. Most cows had normal ovarian cycles and ovulated regularly during both seasons, but quiet ovulations occurred with greater frequency during the hotter times of the year (P < 0.05). Demonstrations of sexual behaviour were affected by choice of footing rather than season. The actual time when cows stood passively and allowed herdmates to complete mounting ranged from 5.1 +/- 0.7 to 5.8 +/- 1 h with access to exercise yards and cement or dirt footing, but declined to only 1.3 +/- 1.1 h when animals were confined to cement (P < 0.05). Similarly, the total duration of oestrus and mean number of interactions were significantly (P < 0.05) reduced during the observation period conducted with cows confined to concrete footing. These findings further emphasize that the duration of oestrus in dairy cows in considerably shorter than the commonly quoted 18 h.     

Evaluation of alternative equations for prediction of intake for Holstein dairy cows

Six prediction equations for dry matter intake (DMI) were evaluated for accuracy with independent data. The equations were selected based on ease of parameter measurement and practical on-farm use. The equations were assessed for accuracy of predicting individual weekly DMI for primiparous (n = 105) and multiparous (n = 136) cows; three-fourths of these cows were supplemented with a sustained-release form of bovine somatotropin (bST). Large variations in accuracy were identified across the six prediction equations for effects of parity and bST. Prediction accuracy of all equations for cows in wk 1 to 24 of lactation was better for primiparous cows than for multiparous cows. Precision of prediction equations was poor for cows in wk 8 through 12 of lactation and for cows in > 40 wk of lactation. The equation for DMI with the best accuracy measured by a low total lactation mean square prediction error was the modified equation of the National Research Council: DMI (kilograms per day) = -0.293 + 0.372 x fat-corrected milk (kilograms per day) + 0.0968 x body weight 0.75 (kilograms). However, the overall mean bias (predicted minus observed) of the prediction of weekly DMI of a single cow was high for all equations, including the modified equation of the National Research Council. For wk 2, 4, 8, 10, and 20 of lactation, the mean bias for the modified equation was +6, +3.4, -1.3, -2.1, and -2.8 kg/d. The accuracy of prediction was lower for cows treated biweekly with bST. High yielding cows and cows treated biweekly with bST had higher milk yields in relation to body weight, and standardized prediction equations for DMI were less accurate.     

Protein density and its influence on metabolite concentration and nitrogen retention by Holstein cows in late gestation

Multiparous Holstein cows in late gestation were used in a completely randomized design to test the effects of prepartum protein supply on prepartum N balance, blood metabolite and hormone concentrations, and postpartum intake and milk production. Cows were assigned to one of three isocaloric diets that differed in amount of total dietary crude protein (CP) (10.6, 12.7, or 14.5% of dry matter) but not in CP degradability or solubility. All diets contained the following ingredients: corn silage, chopped grass hay, ground corn, soybean meal, expeller soybean meal, minerals, and vitamins. Following parturition, all cows were offered a similar diet. Nitrogen balance was measured on d 12 to 7 prior to the expected calving date. Cows were bled on d 5 prior to the expected calving date from just prior to feeding to 8 h postfeeding. As dietary CP increased, plasma glucose concentrations increased linearly, but no change was detected in plasma nonesterified fatty acids or serum insulin concentrations. Nitrogen intake, apparent and true digestibilities, fecal and urinary concentration of and N balance increased as the concentration of dietary protein increased. The efficiency of absorbed protein utilization decreased as protein intake increased. No change in postpartum intake or milk production was observed. An increase in N retention in late gestation cows that were in positive N balance did not increase postpartum milk production.     

Fatty acid composition of milk from Holstein cows fed oleamide or canola oil

Based on previous in vitro results that showed reduced biohydrogenation of oleamide by ruminal microbes, this study was conducted to determine whether the addition of oleamide to the diets of dairy cows would enhance the C18:1 concentration in milk. Nine first lactation Holstein cows were fed three diets in a 3 x 3 Latin square replicated three times. Each period lasted 3 wk. The total mixed diets consisted of 42% corn silage and 58% concentrate (dry matter basis) with either no added fat (control), 3.5% high oleic canola oil, or 3.5% oleamide. Dry matter intake was reduced when oleamide was added to the diet but not when canola oil was added. Milk yields were the same for cows fed all three diets. Canola oil reduced fat-corrected milk yield and milk fat concentration, but these were not affected by oleamide. Milk protein concentration was lower for cows fed oleamide than for cows fed canola oil. Milk C18:1 averaged 23.16% of total fatty acids for cows fed the control diet and increased to 35.13% when canola oil was fed. Oleamide further increased C18:1 to 48.16% of total fatty acids in milk. All fatty acids with > or = 16 carbon chain length were reduced by oleamide. Oleamide was more effective than was canola oil in this study at increasing the oleic acid content of bovine milk. Oleamide reduced dietary intake when added at 3.5% of the dietary dry matter but still had no effect on milk yield or milk composition.     

Effect of infused volatile fatty acids and caseinate on milk composition and coagulation in dairy cows

Milk protein secretion is changed by increasing the proportion of energy, mainly as propionic acid, or the availability of AA. Whether associative effects exist between energy nature and protein amounts is unknown. Therefore, ruminal isoenergetic infusions of low or high propionate mixtures were combined factorially with duodenal infusion of sodium caseinate or control. Four ruminally and duodenally fistulated Holstein cows were used. The diet was limited and consisted of 70% forage and 30% concentrate. Caseinate infusion increased milk yield and protein and casein contents and decreased milk fat content; curd yields and coagulation properties of milk were improved. The infusion of propionic acid caused a large increase in rumen propionate. Milk yield tended to decrease, and milk fat decreased, but protein, casein, and curd yields were unchanged; milk-coagulating properties were improved. No interaction existed between energy and protein amounts. Alteration of VFA had little effect on milk composition, but increasing the protein supply to the duodenum increased milk protein.     

Effect of diseases on the culling of Holstein dairy cows in New York State

The effect of seven diseases on culling was measured in 7523 Holstein cows in New York State. The cows were from 14 herds and had calved between January 1, 1994 and December 31, 1994; all cows were followed until September 30, 1995. Survival analysis was performed using the Cox proportional hazards model to incorporate time-dependent covariates for diseases. Different intervals representing stages of lactation were considered for effects of the diseases. Five models were fitted to test how milk yield and conception status modified the effect of diseases on culling. Covariates in the models included parity, calving season, and time-dependent covariates measuring diseases, milk yield of the current lactation, and conception status. Data were stratified by herd. The seven diseases and lactational risks under consideration were milk fever (0.9%), retained placenta (9.5%), displaced abomasum (5.3%), ketosis (5.0%), metritis (4.2%), ovarian cysts (10.6%), and mastitis (14.5%). Older cows were at a much higher risk of being culled. Calving season had no effect on culling. Higher milk yield was protective against culling. Once a cow had conceived again, her risk of culling dropped sharply. In all models, mastitis was an important risk factor throughout lactation. Milk fever, retained placenta, displaced abomasum, ketosis, and ovarian cysts also significantly affected culling at different stages of lactation. Metritis had no effect on culling. The magnitude of the effects of the diseases decreased, but remained important, when milk yield and conception status were included as covariates. These results indicated that diseases have an important impact on the actual decision to cull and the timing of culling. Parity, milk yield, and conception status are also important factors in culling decisions.     

Modulation of cochlear blood flow by extracellular purines

Humoral adenosine 5'-triphosphate (ATP), adenosine and uridine 5'-triphosphate (UTP) have been shown to have a role in controlling local blood flow in a variety of tissues. The presence of P1 and P2 receptors in the cochlea, and particularly the highly vascular region, the stria vascularis, implies a vasoactive role for these compounds in the inner ear. To test the effect of extracellular purines and pyrimidines on cochlear blood flow, cochleae from anaesthetised guinea-pigs were perfused with ATP (1 microM-10 mM), adenosine (1 microM-10 mM) and UTP (1 mM) in artificial perilymph while blood flow through the cochlea was measured. An acute perilymphatic perfusion technique was established via tubing placed through a hole in the bone overlying scala tympani of the first cochlear turn, with an outlet hole in scala vestibuli of the fourth turn. Blood flow was measured by placing the probe of a laser Doppler blood perfusion monitor on the bone overlying the stria vascularis in the third cochlear turn. ATP and adenosine produced a significant dose dependent increase in cochlear blood flow (28.8-229.0% and 35.8-258.1%, respectively). The effect of ATP (100 microM) on cochlear blood flow was reduced in the presence of reactive blue 2 (1 mM) and pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (1 mM). The blood flow response to adenosine (10 microM) was reduced in the presence of 1,3-dimethylxanthine (theophylline, 100 microM), but not with either 3,7-dimethyl-1-propargylxanthine (10 microM) or 8-cyclopentyl-1,3-dipropylxanthine (10 microM). UTP did not produce any change in the cochlear blood flow. To determine if the ATP effect was also mediated by adenosine derived from ectonucleotidase activity, the perilymphatic compartment was perfused with either ATP plus theophylline (100 microM) or with the non-metabolisable form of ATP, adenosine 5'-O-(3-thiophosphate) (ATPgammaS, 100 microM). The effect of ATP on cochlear blood flow was unaffected with the inclusion of theophylline while ATPgammaS produced an increase in cochlear blood flow similar to the one observed with ATP. These findings indicate that extracellular ATP and its metabolite adenosine have a modulatory role in cochlear blood flow possibly mediated by both P1 and P2 receptors.     

Early lactation responses of Holstein cows fed a rumen-inert fat prepartum, postpartum, or both

Primiparous (n = 22) and multiparous (n = 41) cows were randomly assigned by calving date and parity to one of four dietary sequences of supplemental fat from 14 d prepartum to 151 d postpartum. Partially hydrogenated tallow was added to diets at 0% prepartum and postpartum (control); 1% prepartum and 2% postpartum; 0% prepartum and 2% postpartum; and 0% prepartum, 0% from 1 to 34 d postpartum, and 2% from 35 to 151 d postpartum. Inclusion of partially hydrogenated tallow did not influence yields of milk or 3.5% FCM, milk composition, or DMI during the first 151 d postpartum. During the first 35 d postpartum, cows receiving partially hydrogenated tallow starting at parturition yielded milk with a higher fat content than those receiving fat prepartum and postpartum. Addition of partially hydrogenated tallow to diets starting 35 d postpartum resulted in cows being more persistent in yields of milk and 3.5% FCM from 60 to 151 d postpartum. Reproduction parameters measured were unaffected by time of fat addition to diets. Our data suggest that delaying the addition of partially hydrogenated tallow to diets until 35 d postpartum may improve the persistency of lactation.     

Interactions of tallow and hay particle size on yield and composition of milk from lactating Holstein cows

An 18-wk lactation study was conducted to determine whether the effects of tallow on the lactation performance of dairy cows were influenced by particle size of hay in the ration. A total mixed ration containing 50% concentrate, 25% corn silage, and 25% alfalfa hay (dry matter basis) was fed to Holstein cows. Four total mixed rations were developed based on differences in the percentage of tallow in the concentrate and particle size of alfalfa hay: 1) 0% tallow, long-cut hay; 2) 0% tallow, short-cut hay; 3) 5% tallow, long-cut hay; and 4) 5% tallow, short-cut hay. Ration had no effect on dry matter intake, body weight gain or change in body condition score. Tallow increased milk and milk protein yields but reduced milk protein concentration. However, the effects of tallow on milk and milk protein yields were the same, regardless of hay length in the ration. A tendency for an interaction of tallow and hay particle size was detected for fat-corrected milk (FCM) because tallow increased FCM more when hay was short. Ration had no effect on volatile fatty acids in ruminal samples collected via a stomach tube. In this study, the effects of tallow on milk yield and composition from Holstein cows were the same, regardless of hay particle size in the ration. The tendency for tallow to increase FCM more when hay was short suggests at least a limited role of forage particle size in the determination of how fat supplements in dairy rations affect lactation performance.     

Relationships between the number of small follicles prior to superovulatory treatment and superovulatory response in Holstein cows

In order to determine relationships between the number of small follicles prior to superovulatory treatment and superovulatory response, a total of 55 superovulations were induced in Holstein cows. The ovaries were examined ultrasonographically once 0-1.5 days before the initiation of superovulatory treatment. The number of small follicles 3-6 mm in diameter on both ovaries before superovulatory treatment was found to be significantly correlated with the numbers of corpora lutea after superovulation (r = 0.440, P < 0.001), total ova recovered (r = 0.503, P < 0.001) and transferable embryos recovered (r = 0.482, P < 0.001). These results indicate that a single ultrasonographic examination of follicles 3-6 mm in diameter prior to superovulatory treatment can be utilized to predict superovulatory response.     

Inhibition of insulin release by intraduodenally infused enterostatin-VPDPR in rats

BACKGROUND: Retinopathy of prematurity (ROP) is a retinal vascular disease occurring in infants with short gestational age and low birth weight and can lead to retinal detachment (ROP stages 4 and 5). X-linked familial exudative vitreoretinopathy is phenotypically similar to ROP and has been associated with mutations in the Norrie disease (ND) gene in some cases. OBJECTIVE: To determine if similar mutations in the ND gene may play a role in the development of advanced ROP. METHODS: Clinical examination and molecular genetic analysis were performed on 16 children, including 2 dizygotic and 1 monozygotic twin pairs, and their parents from 13 families. RESULTS: Sequencing of the amplified products revealed missense mutations (R121W and L108P) in the third exon of the ND gene in 4 patients. These mutations were not present in an unaffected premature twin, 2 children with regressed stage 3 ROP, the parents, or in 50 unrelated healthy control subjects. CONCLUSION: These findings suggest that mutations in the ND gene may play a role in the development of severe ROP in premature infants.     

Stabilization of the purine.purine.pyrimidine DNA base triplets by divalent metal cations

An extensive search of aphasia-treatment literature yielded 55 reports of clinical outcomes satisfying the essential criteria for inclusion in a meta-analysis. The results confirmed those of an earlier meta-analysis in demonstrating the utility of aphasia treatments, generally considered, for bringing about desirable clinical outcomes. Beyond the general case, the new findings address clinical utility in finer detail than was previously possible. Effects of treatment for aphasia are synthesized and assessed for each of four important dimensions: amount of treatment, type of treatment, severity of aphasia, and type of aphasia.     

Ataxia induced by small amounts of alcohol

OBJECTIVE: To compare short- and long-term complications after tenectomy of the deep digital flexor tendons or onychectomy and owner satisfaction with these surgical procedures. DESIGN: Prospective cohort study. ANIMALS: 20 cats undergoing tenectomy and 18 cats undergoing onychectomy. PROCEDURE: Cats undergoing tenectomy or onychectomy were monitored for a minimum of 5 months to enable comparison of type and frequency of complications. Owner satisfaction was also assessed. RESULTS: Cats undergoing tenectomy had significantly lower pain scores 24 hours after surgery, compared with those undergoing onychectomy. Type and frequency of other complications did not differ between procedures. Owners appeared to be less satisfied with the tenectomy procedure than with the onychectomy procedure, although scores for satisfaction with each procedure were not significantly different. CLINICAL IMPLICATIONS: Owners should be aware of the high complication rate for both procedures and of the need for constant trimming of claws of cats that have undergone tenectomy.     

Association of myelodysplastic changes with purine analogues

We describe the occurrence of myelodysplastic changes (hypogranular myeloid series and Pelger cells, dyserythropoiesis with ring sideroblasts) in five of 31 patients with chronic lymphoproliferative disorders after treatment with purine analogues. The bone marrows of 31 patients with chronic lymphoproliferative disorders before and after treatment with purine analogues were reviewed. The majority of patients had received extensive prior treatment, but none had dysplastic changes prior to treatment with purine analogues. We suggest that a purine analogue may have been responsible for dysplastic change and that further follow-up of this phenomenon is warranted.     

Determination of trace amounts of urea by using flow injection with chemiluminescence detection

Reaction between urea and hypobromite in alkaline solution was found to produce chemiluminescence with a maximum wavelength at 510 nm. A simple chemiluminescence detection method was used for the determination of urea in human urine and natural aqueous samples, which combined this chemiluminescence reaction with a flow injection analysis system. The relative standard deviation for 5 x 10(-7) mol dm-3 urea is 1.9% (n = 6), and the detection limit is 9.0 x 10(-8) mol dm-3 (3Sr). As this chemiluminescence reaction is very fast, a double concentric tube mixer connected directly to the chemiluminescence cell was used to mix urea solution and hypobromite solution. Alkylamines, carboxylic acids and most amino acids do not interfere in the determination. Ammonium ion interferes, but the sensitivity for ammonium ion is only 1% of that for urea. The interference from ammonium ion was removed sufficiently by using an on-line cation-exchange column.