Biomedical subjects

M R Murphy

Publications and source records attributed to M R Murphy.

At least 73 records · Page 4Linked to original sources

PubMed1990

Toxic interactions between repeated soman and chronic pyridostigmine in rodents.

These experiments examined the interactions of pyridostigmine, a reversible, peripherally acting anticholinesterase, with soman, an irreversible, peripherally and centrally acting anticholinesterase. Lethality, weight change, symptoms, and serum cholinesterase inhibition were determined following five daily injections of soman in rodents implanted with osmotic pumps containing two concentrations of pyridostigmine or vehicle. Concurrent exposure to both anticholinesterases had no effect on any measure at pyridostigmine-induced cholinesterase inhibition levels of 35% or 70% compared to controls. These results emphasize the safety of pyridostigmine as a pretreatment against organophosphate toxicity.

Animals↗

PubMed1990

Effects of niacin source on epinephrine stimulation of plasma nonesterified fatty acid and glucose concentrations, on diet digestibility and on rumen protozoal numbers in lactating dairy cows.

Effects of niacin (nicotinic acid or nicotinamide) supplementation of dairy cow diets on apparent total tract nutrient digestibility, milk yield and milk composition were determined using six mid-lactation Holstein cows in a replicated 3 x 3 Latin square design arranged to test for residual treatment effects. Treatments were control, 12 g/d of nicotinic acid or 12 g/d of nicotinamide. Periods were 14 d long; d 1 to 4 served as an adaptation period before treatment administration commenced (d 5 to 14). Effects of supplemental niacin on plasma nonesterified fatty acid (NEFA) concentrations and plasma glucose concentrations were tested following saline injection on d 10. Blood was then sampled for 5.5 h at 15-min intervals. On d 13, cows were treated similarly except that epinephrine replaced saline. The area below d-10 curves was subtracted from the area below d-13 curves to serve as an indicator of niacin's effect on plasma NEFA and glucose concentration responses to epinephrine injection. Niacin treatments did not change the area differences for plasma glucose compared to the control treatment; however, there was a trend for niacin to reduce the area difference compared to the control treatment for plasma NEFA. Niacin treatments did not alter dry matter intake, nutrient digestibility, milk yield or composition. Niacin supplementation increased the number of entodinia protozoa in rumen fluid.

Animals↗

PubMed1990

Naloxone inhibits oxytocin release at orgasm in man.

We examined the effect of naloxone on plasma oxytocin levels during sexual activity in men. Eight normal men took part in a double-blind, two-period, cross-over design. Mean plasma oxytocin rose to 362% of baseline values at orgasm with placebo (saline) but showed no increase with naloxone (P less than 0.01). While naloxone had no effect on heart rate or blood pressure at orgasm, a decrease in the level of subjective arousal and pleasure at orgasm was noted. We conclude that opioid receptor blockade with naloxone has an inhibitory effect on the neural pathways mediating the oxytocin response at orgasm.

Adult↗

PubMed1990

A new method of phototherapy: nursing perspectives.

Phototherapy is commonly used to treat infants with hyperbilirubinemia. Conventional phototherapy consists of a light source situated approximately 20 inches from an infant who is in an isolette and who is equipped with eye patches. A new method of phototherapy, a fiberoptic blanket, wraps light around the infant's torso delivering continuous phototherapy. The infant can remain in the mother's room in an open crib during treatment without the need for eye patches. We have found this system to have many advantages over conventional phototherapy for hospitalized infants with hyperbilirubinemia.

Fiber Optic Technology↗

PubMed1989

Nutrient digestion in the large intestine as influenced by forage to concentrate ratio and forage physical form.

Digestion in the large intestine was investigated in four growing steers fitted with duodenal and ileal cannulas. Diets assigned within a 4 x 4 Latin square were: 20% long alfalfa hay and 80% grain; 15% pelleted alfalfa, 5% hay, and 80% grain; 80% hay and 20% grain; and 60% pellets, 20% hay, and 20% grain. Intake of DM was not affected by diet. Organic matter digestion in the large intestine averaged 9, 3, 1, and -4% of total tract digestion for the 20% hay, 20% pellet, 80% hay, and 80% pellet diets, respectively, with significant increases due to high grain diets and long hay. Digestion of CP in the large intestine as a percentage of total tract digestion was unaffected by diet but averaged 3, -1, .3, and -6% for the respective diets. Percentage of total tract starch digestion occurring in the large intestine increased with grain feeding and averaged 6, 3, 1, and 1%, respectively. Digestion of ADF and NDF in the large intestine as a percentage of total tract was unaffected by diet; however, the respective means were 16 and 15, 7 and 7, 5 and 15, and 1 and 1%. In a second trail the same animals were fed a more typical dairy cow diet consisting of 50% grain, 25% corn silage, and 25% long alfalfa hay for a single 18-d period. Digestion in the large intestine accounted for 2.1, .2, 3.6, and 6.4% of total tract digestion of organic matter, starch, ADF, and NDF, respectively; however, feed intake was not as great as in the first trail. Although conditions of these studies differed from those commonly experienced by lactating cows, the underlying principals should apply. The large intestine would be expected to make an even greater contribution to total tract digestion in lactating cows consuming proportionally more DM.

Animal Feed↗

PubMed1989

Production of volatile fatty acids in the rumen and cecum-colon of steers as affected by forage:concentrate and forage physical form.

Contribution of cecal and ruminal VFA to metabolizable energy was investigated in steers with cannulas in both the rumen and cecum. Animals were fed ad libitum so that data would be applicable to the lactating dairy cow. Diets assigned within a 4 x 4 Latin square were: 20% long alfalfa hay and 80% concentrate; 15% pelleted alfalfa, 5% hay and 80% concentrate; 80% hay and 20% concentrate; 60% pellets, 20% hay and 20% concentrate. Intake of DM was unaffected by diet. Cecal fluid pH, osmolality, and concentrations of valerate and isovalerate were unaffected by diet. Concentrations of total VFA, acetate, propionate, butyrate, and lactate in the cecum increased with proportion of grain in the diet. The high grain diets depressed cecal ammonia concentration and acetate to propionate ratio. Acetate production in the cecum was higher with the high grain diets whereas that in the rumen was lower. Production of propionate and butyrate in both the cecum and rumen was unaffected by diet. Cecal VFA provided 8.6% of metabolizable energy intake, on average. Contribution of ruminal VFA to total metabolizable energy was affected by diet, accounting for 72, 51, 74, and 52% of metabolizable energy from the 20% hay, 20% pelleted alfalfa, 80% hay, and 80% pelleted alfalfa, respectively. Cecal VFA were an important source of energy for ad libitum-fed steers; this contribution would undoubtedly increase with increasing feed intake.

Animal Feed↗

PubMed1989

Diet digestibility and growth of holstein calves fed acidified milk replacers containing soy protein concentrate.

Three experiments were conducted to determine the effects of acidification of milk replacers containing soy protein concentrate on diet digestibility and growth of Holstein bull calves. In Experiment 1, six calves (6 wk old) were fed at 10% of BW/d either acidified milk replacer containing soy protein concentrate or untreated milk replacer containing soy protein concentrate. Replacers were reconstituted to 12.5% DM for 10-d adjustment and 4-d collection periods to determine digestibility and N balance. Digestibilities of DM, ether extract, and N were similar between treatments. Nitrogen retention and N retention as a percentage of that absorbed were higher for calves fed the acidified diet. In Experiment 2, 20 calves (1 wk old) were fed diets identical to those diets fed in Experiment 1 at 20% of BW/d for 4 wk. Calves were allowed to adjust to the diet for 5 d. Growth parameters were measured and amount of feed offered was adjusted weekly. Calves fed the untreated diet had higher daily weight gains, girth gains, height gains, and better feed utilization. In Experiment 3, 21 calves were fed either the aforementioned diets or a replacer based on milk proteins at 10% of BW/d (12.5% DM) for 4 wk. Growth parameters were measured and DM intakes were adjusted weekly. Growth and feed conversion were similar across diets. Replacers containing soy protein concentrate or large amounts of whey may need to be supplemented with additional methionine to maximize rate of gain.

Amino Acids↗

PubMed1989

Passage and rumination of inert particles varying in size and specific gravity as determined from analysis of faecal appearance using multicompartment models.

Plastic particles of defined length (2, 5 mm) and specific gravity (sp.gr. 1.10, 1.34, 1.77) were administered just before feeding into the reticulo-rumen of four cattle and four swamp buffaloes given a diet predominantly of rice straw ad lib. Simultaneously, doses of ground rice straw marked with Cr and Yb were likewise given. Plastic particles were recovered from faeces for 12 d after dosing, and divided into non-ruminated (NR) and ruminated (R) particles. Excretion data of plastic particles were interpreted using a four-pool model incorporating passage of NR (kp) and R from the reticulo-rumen, post-ruminal passage, rate of chewing (kr) and two lag times. An inverse relationship was found between kr and sp.gr. The kr was higher for 5 mm than that for 2 mm particles. In contrast, kp was greatest for particles of sp.gr. 1.34, with higher kp for 2 mm than for 5 mm particles. Rates of passage and rumination (kp, kr) were higher for buffaloes than for cattle. Rumination time was related to kr, most highly (r2 0.96) with kr of 2 mm, 1.10 sp.gr. particles. Fragmentation of 5 mm particles by rumination tended to increase the rate of passage from the rumen. Ruminal passage rates of Yb and Cr markers were poorly correlated with each other and with kp of any of the plastic markers. Reanalysis of published data from plastic particle studies supported the relationships between sp.gr., size, kp and kr.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1988

Effect of forage physical form on chewing activity, dry matter intake, and rumen function of dairy cows in early lactation.

To examine the effects of reducing forage particle size on production, chewing, and digesta kinetic parameters in early lactation, 42 Holstein cows (9 ruminally cannulated) were assigned 14 d postpartum to one of three experimental diets with concentrate: alfalfa haylage: alfalfa pellets ratio of A) 60:40:0;B) 60:28:12; and C) 60:12:28 on a DM basis. The trial ran through the 12th wk postpartum, and measurements of chewing activity and rumen parameters were made during the 4th, 8th, and 12th wk postpartum. Dry matter intake (kg/d), milk production (kg/d), and milk fat percentage for diets A, B, and C were 23.1, 23.0, 18.8; 33.7, 35.5, 31.8; and 3.1, 2.9, 2.6, respectively. Rumen parameters and chewing activities were linearly related to haylage in the diet. Ruminal fluid dilution rate (%/h), volume (L), and outflow (L/d), rumination (min/d), total chewing (min/d), total chewing (min/kg DM intake), ruminal acetate (molar %), and NDF digestibility (%) were 16.6, 13.8, 10.0; 62, 58, 54; 243, 193, 137; 437; 367, 204; 649, 566, 376; 28.2, 24.1, 20.0; 58.6, 56.3, 53.8; and 32, 37, 23, respectively. These results suggest that dairy cattle in early lactation require a minimum amount of effective fiber to optimize production and intake. This requirement was met when 28%, but not 12%, of dietary DM was alfalfa haylage.

Animal Feed↗

PubMed1988

Dietary alteration of particle breakdown and passage from the rumen in lactating dairy cattle.

To evaluate the effect of dietary alteration on the rates of ruminal small particle passage or large particle breakdown, six ruminally cannulated Holstein cows 90 d postpartum were used in a 3 X 3 Latin square design. Experimental diets were 1) control: 60% concentrate, 40% corn silage; 2) bicarbonate: 60% concentrate (containing 2% sodium bicarbonate), 40% corn silage; and 3) hay: 60% concentrate, 30% corn silage, and 10% long alfalfa hay on a DM basis. Dry matter intake (kg/d), milk production (kg/d), percentage milk fat, rumination (min/d), ruminal fluid outflow (L/d), small particle (150 to 850 micron) passage rate (%h), and large particle (greater than 4.25 mm) breakdown rate for diets control, bicarbonate, and hay were 20.2, 20.9, 22.4; 26.6, 27.7, 26.8; 3.5, 3.6, 3.2; 405, 350, 370; 167, 184, 185; 6.5, 7.6, 7.4; and 7.2, 6.8, 7.4, respectively. Rumen DM content and digesta particle size were reduced at the end of a 24-h feeding period. Data suggested that small particle passage may be more closely related to ruminal fluid outflow and DM intake than large particle breakdown rate.

Animal Feed↗

PubMed1987

The enflurane sparing effect of sufentanil in dogs.

There is a ceiling to the reduction of enflurane MAC by fentanyl in the dog. Sufentanil (SUF), a more potent narcotic, may be more efficacious in reducing enflurane MAC. To test this hypothesis, 25 mongrel dogs were studied in three groups. Group 1 (n = 8) received SUF in progressively increasing infusion rates from 0.005 micrograms . kg-1 . min-1 to a maximum of 1.215 micrograms . kg-1 . min-1. MAC was determined at stable SUF concentrations in plasma [SUF] during each infusion rate. Group 2 (n = 10) received SUF at a dose rate (0.007 micrograms . kg-1 . min-1) designed to produce approximately 35% MAC reduction, and MAC determinations were made at regular intervals over a mean infusion time of 7.6 +/- 0.43 h (mean +/- SEM). Group 3 (n = 7) received 1.215 micrograms . kg-1 . min-1 and were studied as in group 2 over an infusion time of 6.7 +/- 0.42 h. In group 1, the highest infusion rate (1.215 micrograms . kg-1 . min-1) produced [SUF] = 48 ng/ml and reduced MAC by 71 +/- 6%. This was not statistically different from the reduction which occurred at [SUF] = 0.92 ng/ml (57 +/- 7%; infusion rate 0.015 micrograms . kg-1 . min-1; P = 0.21). In group 2, the degree of MAC reduction achieved by stable [SUF] (0.54 +/- 0.08 ng/ml) declined over time (MAC reduction at start = 34 +/- 2% versus 18 +/- 4.0% at the end of the infusion; P = 0.001), suggesting the development of tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Changes in oxytocin and vasopressin secretion during sexual activity in men.

We measured plasma oxytocin (OT) and arginine vasopressin (AVP) concentrations in 13 normal men during sexual arousal and ejaculation. Mean plasma AVP increased from 1.4 +/- 0.2 (+/- SE) to 5.3 +/- 1.7 pmol/L (P less than 0.05) during arousal, but there was no significant change in OT. In contrast, at ejaculation mean plasma OT rose from a basal value of 1.4 +/- 0.3 to 7.3 +/- 0.6 pmol/L (P less than 0.01) and then fell to basal concentrations in 30 min. AVP, however, had returned to basal levels at the time of ejaculation and remained stable thereafter. We conclude that in man AVP is secreted during sexual arousal, and there is, subsequently, a selective release of OT at the time of ejaculation.

Adult↗

PubMed1987

Effects of feeding or infusing ammonium salts of volatile fatty acids on ruminal fermentation, plasma characteristics, and milk production of cows.

Eight rumen-fistulated Holstein cows, averaging 77 d postpartum, were used in a replicated 4 X 4 Latin square design with 28-d periods to investigate the effect of ammonium salts of isobutyrate, 2-methylbutyrate, isovalerate, and n-valerate on animal performance and their possible mechanism(s) and site(s) of action. Each cow was fed ad libitum a complete mixed diet of 55% corn silage and 45% concentrate on a dry basis that was supplemented with 1.8 kg of premix daily. Treatments were 1) control, 2) ammonium salts of volatile fatty acids in premix, 3) ammonium salts of volatile fatty acids ruminally infused, or 4) ammonium salts of volatile fatty acids abomasally infused. Mean ruminal fluid pH and concentrations of ammonia and volatile fatty acids for treatment comparisons were not different. Plasma concentrations of isobutyrate, 2-methylbutyrate, and valerate differed among treatments, but there was no significant effect on dry matter intake, milk production, milk composition, or efficiency of feed utilization. Apparent nutrient digestibility; disappearance of dry matter, cellulose, and nitrogen from polyester bags suspended in the rumen; and plasma concentrations of glucose, free fatty acids, and growth hormone also were not significantly affected by treatment.

Abomasum↗

PubMed1987

Abomasal pH, nutrient digestibility, and growth of Holstein bull calves fed acidified milk replacer.

Our objective was to compare nutrient digestion and utilization, amount and pattern of intake, and pH profile over time of abomasal contents in calves offered acidified milk replacer ad libitum or regular (sweet) milk replacer twice daily at 10% of body weight per day. Ten Holstein bull calves were fed replacers reconstituted to 13% dry matter for 4 wk. Daily milk replacer and water consumption and weekly body weight were recorded. Other variables were measured during the 2nd and 4th wk. Calves offered acidified replacer consumed more dry matter and gained more body weight than did calves fed sweet replacer; however, there was no difference in feed conversion ratio. Apparent digestibility of dry matter, ether extract, nitrogen, and retention of absorbed nitrogen were not affected by treatment. Acidified milk replacer offered ad libitum lowered the pH of abomasal contents and feces compared to regular replacer offered at 10% of body weight per day. Feeding patterns of calves offered acidified replacer ad libitum were variable. No adverse effects of feeding acidified milk replacer were noted.

Abomasum↗

PubMed1987

Supplying the protein needs of dairy cattle from by-product feeds.

Several by-product feeds are relatively high in crude protein and exhibit relatively low ruminal degradability, which make them desirable proteinaceous feeds for dairy cows. Therefore, by-product feeds have been and will continue to be important feeds for dairy cows. Factors are discussed that affect ruminal degradability of protein in distillers grains, distillers grains with solubles, brewers grains, corn gluten feed, corn gluten meal, meat meal, meat and bone meal, blood meal, and fish meal, and the potential of these feeds to provide supplemental amino acids needed by lactating dairy cows. The importance of maximizing synthesis of microbial protein and digestion of organic matter in the rumen is emphasized in relation to total amino acid passage to the small intestine. For these feeds to be used most successfully, they must be available from a dependable source at an economical cost and should supply amino acids that complement other amino acids passing to the small intestine. Benefits that should be realized from the successful use of by-product feeds include increased milk production from feeding proteins that have greater ruminal escape potentials and a reduced cost per unit of milk produced because of decreased use of expensive supplemental protein.

Animal Feed↗

PubMed1987

Dezocine-MAC reduction and evidence for myocardial depression in the presence of enflurane.

The effect of dezocine, an agonist-antagonist opioid analgesic, on enflurane MAC (EMAC) was measured in dogs and, in a separate study, the hemodynamic effects of IV bolus doses of dezocine in the presence of a stable end-tidal enflurane concentration were measured. Study 1 (n = 8)--EMAC Reduction: Dezocine reduced EMAC in a dose-dependent fashion by a maximum of 58 +/- 3% (mean +/- SEM) after injection of 20 mg/kg. Cardiac toxicity prevented administration of higher doses. Study 2--Hemodynamics: Group 1 (n = 7) received dezocine 0.2, 1.5, 5, and 20 mg/kg IV each as a bolus over 30 sec. Group 2 (n = 5) was studied in exactly the same manner except that instead of dezocine, each dog received drug carrier solution alone (carrier). Significant hemodynamic differences between carrier and drug groups were observed only at the 20 mg/kg dose level, which produced death in one dog and a decrease in mean aortic pressure to 39 +/- 5% of baseline, in cardiac output to 60 +/- 9% of baseline, and in stroke volume to 69 +/- 9% of baseline in the remaining dogs. It is concluded that dezocine produces a dose-dependent reduction in EMAC limited by cardiovascular toxicity. This toxicity appears to be related to direct myocardial depression by high doses of dezocine in the presence of enflurane.

Analgesics↗

PubMed1986

An update of a dynamic model of ruminant digestion.

The progressive development of a dynamic model of ruminant digestion for evaluation of factors affecting nutritive value of feedstuffs is outlined. Significant changes have been introduced in many of the interactive subunits that accommodate the digestion of 12 chemical constituents (soluble carbohydrate, organic acids, starch, pectin, hemicellulose, cellulose, lipids, soluble protein, insoluble protein, nonprotein N, lignin and ash), microbial growth, animal interactions and summary computations. Explicit consideration of soluble carbohydrates, organic acids and pectins has been replaced by an aggregate fraction. A section has been added to follow dynamic aspects of volatile fatty acid metabolism in the rumen. Evaluations of the model were made by comparing its behavior with that observed experimentally for sheep fed a number of diets. These included an alfalfa diet fed at two intake levels either hourly or once daily, a dried subterranean clover diet fed hourly, a forage oat diet fed every 3 h and an 80% concentrate diet fed twice daily. For frequently fed diets, model estimates, in general, agreed very well with experimental estimates. Although changes in representations of protein metabolism were helpful, the pool size of ruminal ammonia N was not simulated well. Digestion and passage in the model occurred more rapidly than was observed when animals were fed high-quality forages once daily and rates of particle size reduction, fermentation and passage were lower than observed when low-quality diets were fed. It was concluded that the model can serve as a useful and adaptable tool for analyzing factors affecting nutritive value. Particle size reduction and passage from the rumen, dynamics of protein metabolism and utilization, and water dynamics were identified as areas requiring further research.

Animals↗

PubMed1986

Effect of source of carbohydrate and frequency of feeding on rumen parameters in dairy steers.

Four rumen-fistulated, Holstein steers (358 kg) were fed two diets at two frequencies (2 and 8 times/d) in a 4 X 4 Latin square design with 28-d periods. The two diets consisted of corn silage and a concentrate mixture in a ratio of 40:60 on a dry matter basis. The two concentrate mixtures (control and dried whole whey) contained, as a percentage: ground shelled corn, 87.85, 19.05; soybean meal, 9.4, 5.9; dicalcium phosphate, 1.7, 0; trace mineralized salt, 1.0, 1.0; vitamin A and D premix, .05, .05; and dried whole whey, 0, 74.0, respectively. Rumen fluid samples were taken at hourly intervals for 24 h and analyzed for pH, volatile fatty acids, lactate, ammonia nitrogen, and protozoal numbers. Total concentration of volatile fatty acids in the rumen were not affected by treatments. Feeding the control diet resulted in significantly higher ruminal acetate and isovalerate but lower butyrate and valerate expressed as a molar percentage. Increasing the feeding frequency from 2 to 8 times/d resulted in an increase in the molar percentage of acetate and a decrease in the concentration of lactate in ruminal fluid. Numbers of protozoa varied considerably with time after feeding and tended to be higher on the whey diet.

Ammonia↗