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Biomedical subjects

M F Smith

Publications and source records attributed to M F Smith.

At least 235 records · Page 13Linked to original sources
PubMed1984

Hearing conservation in acoustic neurilemmoma surgery via the retrosigmoid approach.

Hearing conservation in acoustic neurilemmoma surgery is possible in approximately 50% of patients whose tumors measure 15 mm or less in size (medial to the porus acusticus) and whose speech discrimination score in the ear with the tumor is 80% or better. The concepts of total tumor removal and maximum sparing of adjacent normal neural tissue are consistent with efforts to retain cochlear function. A retrosigmoid approach is favored over the middle cranial fossa approach because of the superior exposure and less morbidity. An operating table capable of 35-degree side rotation is used. It allows the majority of patients with acoustic neurilemmoma to be operated on in the horizontal supine position. The posterior lip of the internal auditory canal is removed to within approximately 1.5 mm of the falciform crest. Tumors not extending to the fundus afford an ideal situation for total removal, early identification of the seventh cranial nerve, and conservation of hearing. The CO2 laser is a useful surgical tool with its properties of vaporization, cutting, and coagulation.

Hearing Loss↗
PubMed1984

Effect of prostaglandin F2 alpha on the adenylate cyclase and phosphodiesterase activity of ovine corpora lutea.

The objective of the present study was to determine the temporal relationships among luteal adenylate cyclase activity, luteal phosphodiesterase activity, luteal progesterone concentration and plasma progesterone concentration during prostaglandin F2 alpha (PGF2 alpha)-induced luteolysis in ewes. Corpora lutea (CL) were removed from cycling ewes on d 9 (d 0 = first day of estrus) at 0, 2, 4, 6, 12 and 24 h (seven to eight ewes/group) after PGF2 alpha administration (im). Jugular blood samples were collected at the time of enucleation of CL and analyzed for progesterone. Plasma and luteal progesterone concentrations were decreased (P less than .05) by 4 and 12 h after PGF2 alpha injection, respectively. Basal adenylate cyclase, luteinizing hormone (LH)-activated adenylate cyclase, guanylylimidodiphosphate [Gpp(NH)p]-activated adenylate cyclase and LH plus Gpp(NH)p-activated adenylate cyclase activities were decreased (P less than .05) by 2 h after PGF2 alpha injection. The decrease in adenylate cyclase activity paralleled the decrease in plasma progesterone concentration over time. Luteinizing hormone stimulated (P less than .05) adenylate cyclase activity relative to basal activity at 0, 2, 12 and 24 h post-PGF2 alpha; whereas, Gpp(NH)p stimulated (P less than .01) adenylate cyclase activity relative to basal activity at each time point. In contrast to the decrease in adenylate cyclase activity, phosphodiesterase activity was increased (P less than .05) at 2 and 4 h post-PGF2 alpha. These results suggest that a decrease in adenylate cyclase activity coupled with an increase in phosphodiesterase activity may decrease the intracellular adenosine 3',5' cyclic monophosphate (cAMP) concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1982

Seminal selenium concentrations and spermatozoal abnormalities in beef bulls.

The relationship between seminal selenium (Se) concentration and spermatozoal abnormalities in 24 Angus and 12 Simmental bulls maintained on a Se adequate diet was studied. Two semen samples were collected by electroejaculation 50 days apart from each bull. Measurements of primary and secondary spermatozoal abnormalities, seminal Se concentration, and blood plasma Se concentration were determined at each semen collection. The mean (chi +/- SD ) Se concentration of semen (0.535 +/- 0.267) was approximately 8 fold greater than the Se concentration of blood plasma (0.069 +/- 0.066) and the values were similar for both collections. Spermatozoa concentration was correlated (r = 0.50; P<.01) with seminal Se concentration; however, seminal Se concentration was not highly correlated (P<.01) with primary spermatozoal abnormalities (r = -0.29) and secondary spermatozoal abnormalities (r = 0.16). This study indicates that the Se concentration of semen is high relative to blood plasma in bulls maintained on a Se adequate diet; however, the seminal Se concentration is not highly correlated with spermatozoal abnormalities.

Journal Article↗
PubMed1982

Effect of steroids and/or 48 HR calf removal on serum luteinizing hormone concentrations in anestrous beef cows.

Serum luteinizing hormone (LH) concentrations were quantified in 27 thin, anestrous cows with suckling calves in each of three treatment groups: Syncro-Mate-B (SMB), 48 hr calf removal (CR), and SMB plus CR (SMB + CR). The SMB treatment consisted of a 9 day ear implant containing 6 mg norgestomet and an intramuscular injection containing 3 mg norgestomet and 6 mg estradiol valerate given at the time of implant placement. In the SMB + CR group, CR began at the time of implant removal (0 hr). Blood samples were collected every 4 hr via puncture of a tail vessel beginning 12 hr prior to implant and/or CR and continued for 72 hr thereafter. Before implant and/or CR (-12 to 0 hr), LH concentrations were higher (P<.01) in the CR (1.1 ng/ml) group than in the SMB (.6 ng/ml) and SMB + CR (.8 ng/ml) groups. Following implant and/or CR (4 to 48 hr), LH concentrations increased (P<.01) in the CR (1.8 ng/ml) and SMB + CR (1.3 ng/ml) groups, but remained unchanged in the SMB (.7 ng/ml) group. Furthermore, LH concentrations were higher (P<.05) in the CR group compared to the SMB + CR group. Circulating concentrations of LH declined (P<.01) to 1.2 ng/ml in the CR group following calf return, but remained unchanged in the other two groups. Although more (P<.01) cows in the SMB and SMB + CR groups were detected in estrus than in the CR group, there was no difference (P.10) in the number of cows ovulating between the three treatment groups. These results suggest that CR will increase circulating LH concentrations by 24 hr post CR and that SMB may partially suppress the CR induced LH release following implant and calf removal.

Journal Article↗
PubMed1982

Fertilization rate and early embryonic loss in Brahman crossbred heifers.

The fertilization rate and incidence of embryonic loss in virgin Brahman crossbred heifers between d 3 and 35 postinsemination (d 0 = first day of estrus) were determined. One hundred fifty-five virgin heifers, maintained in a dry lot, received approximately 22 Mcal.head-1.d-1 and were allotted to one of three groups (d 3, 16 or 35) according to body weight at the time of estrous detection. Seven empty ruptured zona pellucidae (ERZP) were recovered from five heifers in the d 3 group. It was impossible to determine whether the ERZP originated from fertilized or unfertilized ova and whether they were ovulated at the estrus immediately preceding or during a previous cycle. Consequently, the fertilization rate (d 3) was calculated to be 80 or 93% depending upon whether the ERZP were included or deleted from the calculations, respectively. Because of the large number of ERZP recovered, a second study was conducted with an additional 21 virgin Brahman crossbred heifers from which ova were recovered on d 3 postinsemination. The results of the two studies were similar. The percentage of heifers with an embryo on d 16 was 78 (10% had degenerating embryos and 12% no embryos), and the percentage pregnant at d 35 was 72. The conclusions suggested from this study depend upon the classification of the ERZP. If the ERZP are designated as ova ovulated during a previous cycle or ova damage in the collection process and are deleted from the calculations, the fertilization rate is high (93%), and embryonic loss apparently occurs between d 3 and 35 (P less than .95). However, if the ERZP are classified as ova ovulated at the immediately preceding estrus, unavailable for further embryonic development, and are included in the calculations, the fertilization rate is comparatively low (80%). In the latter case, the primary loss of potential embryos occurs before d 3, and the loss after d 3 is negligible (P greater than .05).

Animals↗
PubMed1982

Inhibition of forskolin-activated adenylate cyclase by ethanol and other solvents.

Ethanol and a variety of solvents are known to activate basal and Gpp(NH)p- and hormone-stimulated adenylate cyclase. We report here that ethanol and other solvents inhibit the activation of adenylate cyclase by forskolin. In the presence of 10 microM forskolin, 2% ethanol gives about 20% inhibition and 5% ethanol gives 40% inhibition of enzyme activity. Analysis of ethanol inhibition at several forskolin concentrations suggests that inhibition is competitive versus forskolin. Thus the effect of ethanol is greater at low forskolin concentrations and minimal at high concentrations. In addition to ethanol, inhibition of forskolin activation was observed with acetone, n-butanol, t-butanol, dimethyl formamide, dioxane, methanol and n-propanol. Dimethyl sulfoxide was inhibitory only at high concentrations (10%). Since some solvent is needed to prepare forskolin solutions and to maintain solubility at higher concentrations, the inhibitory effects reported here are an important consideration in studies employing forskolin activation. To minimize solvent inhibition we recommend that dimethyl sulfoxide be used to prepare forskolin solutions. At concentrations of 5% and less, dimethyl sulfoxide gives little if any inhibition of forskolin activation and causes only small increases in basal activity.

Adenylyl Cyclase Inhibitors↗
PubMed1982

Nutrition and public health in the Dominican Republic.

A nutrition survey was carried out in a mountainous region southwest of Santiago, Dominican Republic, to determine the extent of malnutrition in the area and to obtain information regarding food beliefs and practices needed to design a viable nutrition program. A stratified cluster sampling technique was used to interview 295 mothers of preschool children and examine 448 of their children under five years of age. The incidence of moderate and severe malnutrition was less than expected. Only 12.3% of the children were less than or equal to 75% of the National Center for Health Statistics (NCHS) reference standard for weight/age; however, 6.5% were greater than 110% of the standard. Children from large, poor families were most vulnerable to growth retardation. Definite meal patterns were identified that included varied sources of cereal products and animal and mixed vegetable proteins. Milk and sausage consumption had a significant positive association with all three growth parameters. Suggestions were made for further research and program development.

Child, Preschool↗
PubMed1981

Relationships among fertility, scrotal circumference, seminal quality, and libido in Santa Gertrudis bulls.

Forty Santa Gertrudis bulls were used to examine relationships among scrotal circumference, seminal quality, libido, and fertility [assessed as the percent pregnant of estrous females (PE rate) and the percent pregnant of females mated (PM rate)]. These bulls were selected from 220 two year old bulls to represent variations in scrotal circumference and seminal quality. Each of the 40 bulls were exposed to 100 cyclic Santa Gertrudis heifers for a 4-day (96 hr) breeding period. The number of estrous females available to each bull varied from 12 to 27. A breeding soundness examination (BSE) was conducted on each bull approximately 45 days prior to the 4-day breeding period and immediately after the 4-day breeding period. The three components of the BSE scroe (scrotal circumference, spermatozoal abnormalities and spermatozoal motility) were not significantly correlated with PE rate or PM rate at either evaluation. There was no significant correlation between PM rate and scrotal circumference; however, each of the 4 bulls having a scrotal circumference less than 30 cm had a PM rate below 31%. Relationships between seminal quality and PM rate were unclear and differed between the two evaluations. There was a trend for bulls having poor seminal quality at the first evaluation to improve by the second evaluation. Consequently, fluctuations in seminal quality between evaluations is one possible explanation for low correlations between seminal parameters and PM rate. Libido (number mated/number in estrus x 100) was positively correlated (r = 0.44) with PE rate. Using a stepwise regression procedure, the independent variables accounting for the most variation in PE rate (dependent variable) included libido, secondary spermatozoal abnormalities, and BSE score (r(2) = 0.44). Results of this study indicate that current methods of fertility evaluation did not accurately predict the fertility of individual Santa Gertrudis bulls as measured by PE rate and PM rate during a 4 day breeding period.

Journal Article↗
PubMed1981

Rubella and juvenile chronic arthritis.

A 9-year-old boy with a clinical illness similar to juvenile rheumatoid arthritis was found to have rubella virus in the synovial fluid. There was complete remission of symptoms after 3 months. The role of rubella virus as a possible possible aetiological agent in juvenile rheumatoid arthritis is discussed.

Arthritis, Juvenile↗
PubMed1980

Effect of monensin, energy level, and cow body condition on pregnancy rate in nonlactating beef cows.

One hundred eighty-two nonlactating cycling Brahman crossbred and Angus cows were used to study the effects of monensin, cow body condition and supplemental energy level on pregnancy rate. The cows were classified as being in either moderate or poor body condition at the start of the experiment and were fed either 9 or 18 Mcal of supplemental metabolizable energy/head/day with or without 125 mg of monensin in the ration. Feeding commenced 21 days prior to and throughout a 45-day breeding season. In the monensin treated group ruminal propionic acid levels (molar %) were increased (P<.01) while acetic and butyric acid levels were lowered (P<.05) regardless of supplemental energy intake. Pregnancy rate, pregnancy rate at first service, and the percentage of conceptions per estrus were increased (P<.05) when cows were fed 18 Mcal of supplemental energy per head per day. Neither cow body condition nor addition of monensin to the diet had an effect on the preceding reproductive endpoints. Cows in poor body condition and receiving 18 Mcal of supplemental energy per head per day had increased (P<.05) reproductive performance as evidenced by an increase in the pregnancy rate, pregnancy rate at first service, and percentage of conceptions per estrus when compared to the other groups.

Journal Article↗