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Biomedical subjects

L F Miller

Publications and source records attributed to L F Miller.

6 recordsLinked to original sources
PubMed1991

Creation of a feline model of obstructive uropathy.

The aim of this project was to create a reproducible, quantifiable feline model of obstructive uropathy. Seventy-three adult female cats of comparable age were evaluated to obtain the normal control urodynamic data base. Twenty-four cats had a silastic cuff installed around the urethra to induce bladder outlet obstruction, and eight underwent a sham operation. Repeated urodynamic evaluations were performed at predetermined postoperative intervals. The obstructed and normal cats inhibited detrusor contractility by reflex striated urethral sphincter activity. Measurements of voiding pressure to verify the presence, and to assess the degree of induced outlet obstruction, required paralysis of the sphincter by curare. Following cuff implantation, voiding pressure increased from a mean normal of 17.2 cm./H2O to 31.6 to 42.5 cm./H2O in animals designated as moderately obstructed, and to 101.7-125.0 cm./H2O in animals designated as severely obstructed. 84.6% of the high pressure bladders developed vesicoureteral reflux. Analysis of resting, low bladder volume, urethral pressure profile (UPP) data and voiding pressures indicate a compensatory sphincteric response to filling in non-curarized animals, and a lack of that response in curarized animals. It appears that implantation of a silastic cuff to prevent full opening of the urethra during voiding, without actually compressing it, is a reasonable model of obstructive uropathy. The observation that the relationship between striated urethral sphincter activity and inhibition of detrusor contractility is influenced by administration of curare was unexpected, and may have clinical implications.

Animals↗
PubMed1991

Interaction of somatotropin and genotype on the requirement for energy in two lines of finishing pigs.

Eighty barrows were used in a 2 x 2 x 4 factorial experiment to examine the effects of genetic line (Hampshire x Yorkshire, H x Y, and Yorkshire x Landrace, Y x L), somatotropin (dose, 0 and 5 mg/d) and energy intake (ad libitum, 93%, 86% and 80%) on growth performance and energy requirements for lean gain over the finishing phase of growth. Four diets were formulated to maintain equal intakes of protein, vitamins and minerals at different energy intakes. Somatotropin increased growth rate 30 to 35% across diets despite an 8 to 12% reduction in ad libitum feed intake. Lean growth rate (kg/d) was increased preferentially by ST in the faster-growing H x Y barrows, which showed a 2.8-fold greater maximum rate increase than the slower-growing Y x L barrows. In control barrows, 10% reductions in energy intake had no effect on lean gain and improved feed/lean gain about 10%. In somatotropin-treated barrows, lean gain was reduced with each energy restriction in H x Y; energy intake had no effect on lean gain in Y x L barrows. Feed/lean gain was improved 22% in Y x L barrows at the lowest energy intake. Data indicate that somatotropin accentuates breed differences in lean gain and energy requirements. Pigs with low lean-growth potential will benefit from restricted feeding, whereas strategies to increase energy intake in pigs with high lean-growth potential may be desirable.

Animal Feed↗
PubMed1991

The effects of recombinant porcine somatotropin on reproductive function in gilts treated during the finishing phase.

The objective of this study was to determine the effects of recombinant porcine somatotropin (rpST) treatment during the finishing phase on subsequent reproductive function in crossbred gilts. Forty gilts weighing 50 kg and housed in a swine finishing facility were randomly assigned to control or rpST treatment. Four control and four rpST-treated gilts were allotted per pen. Twenty rpST-treated gilts received 6 mg of rpST.gilt-1.d-1 in 1 ml of buffered carrier and 20 control gilts received 1 ml of buffered carrier.gilt-1.d-1. Injections were administered daily at 1400 in the extensor muscle of the neck. All gilts received an 18% CP diet containing 1.2% lysine. Treatment was terminated when the average weight in each pen reached 110 kg. Gilts treated with rpST gained more weight (P less than .05) than control gilts (59.8 +/- 1.0 vs 53.5 +/- 1.0 kg). Age at puberty was not different (rpST, 182.2 +/- 3.3; control 181.4 +/- 3.1 d). Prior treatment with rpST did not significantly affect length of estrus (rpST, 1.9 +/- .1; control, 1.8 +/- .1 d) or estrous cycle length (rpST, 20.6 +/- .4; control, 20.4 +/- .4 d). Ovulation rates at second estrus were similar for rpST gilts (15.1 +/- .5) and control gilts (14.4 +/- .5). More embryos (P = .10) were recovered on d 9 to 12 of gestation from rpST-treated gilts than from control gilts (13.1 +/- .9 vs 10.7 +/- .9).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Short term functional effects of bladder outlet obstruction in the cat.

Experimental bladder outlet obstruction in cats was produced by surgical placement of a silastic cuff around the urethra. Two sizes of cuff were used to produce either moderate or severe obstruction. The following is a summary of the short-term effects on bladder function. Obstruction induced a significant increase in the in vivo voiding pressure, in proportion to severity of the obstruction. There were no significant differences between control and obstructed cats in bladder mass, response of the isolated whole bladder to field stimulation or bethanechol, response of isolated bladder strips to field stimulation, bethanechol and ATP, or muscarinic receptor density in the bladder body. Although there were no differences in bladder mass between control and obstructed bladders, the hydroxyproline concentration of the severely obstructed bladders was significantly reduced. Creatine phosphate concentration was also significantly reduced in obstructed bladders. Although all whole cat bladder preparations displayed spontaneous contractile activity during in vitro cystometry, the obstructed bladders had a greater amplitude and frequency of spontaneous contractions with a lower volume threshold. In addition, the obstructed bladders had a greater tetrodotoxin-resistant contractile response to field stimulation. These results suggest that the obstructed cat bladder can compensate for increased outlet resistance without induction of bladder hypertrophy or significant functional changes, as seen in both rat and rabbit.

Adenosine Triphosphate↗
PubMed1977

Nitrones. 7. alpha-Quinoxalinyl-N-substituted nitrone 1,4-dioxides.

A series of alpha-quinoxalinyl-N-substitute nitrone 1,4-dioxides has been synthesize and evaluated as antibacterial and antiprotozoal agents. Structure-activity relationships are discussed. Of the compounds tested, alpha-(3-methyl-2-quinoxalinyl)-N-methylnitrone 1,4-dioxide (2) was the most active agent in vivo against the gram-negative and the gram-positive organisms.

Animals↗