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Biomedical subjects

M F Smith

Publications and source records attributed to M F Smith.

At least 217 records · Page 12Linked to original sources
PubMed1987

A comparison of oto-acoustic emissions and brain stem electric response audiometry in the normal newborn and babies admitted to a special care baby unit.

Brainstem auditory evoked potentials and oto-acoustic emissions have been recorded in 30 normal newborns and in 112 infants admitted to a special care baby unit as part of a study to determine whether these tests can be used to detect the hearing impaired infant. All the ears tested in the normal newborns, where the infant was quiet enough to complete the test, produced a brain stem electric response at a stimulus level less than or equal to 53 dB nHL (dB relative to normal hearing) and 96% produced an oto-acoustic emission at the highest level tested of 41 dB nHL. The mean threshold of the oto-acoustic emission in the normal newborns was 17.7 dB lower than the mean brain stem electric response threshold. The range of thresholds were similar. In the special care infants 84% of ears produced a brain stem electric response at a screening level of 43 dB nHL and 81% of ears produced an oto-acoustic emission at a screening level of 31 dB nHL.

Acoustic Stimulation↗
PubMed1987

Effect of the uterus on subnormal luteal function in anestrous beef cows.

The effect of the uterus on luteal lifespan and pattern of secretion of progesterone following early weaning of calves from anestrous beef cows was studied. Calves were weaned from 15 anestrous beef cows 23 to 33 d postpartum, and cows were allotted to a control (sham surgery, n = 8) or a hysterectomy (n = 7) group, with surgery performed at weaning. Cows in the hysterectomy group were injected (im) with 25 mg prostaglandin F2 alpha (PGF2 alpha) approximately 20 d after first estrus (d 0). The interval from weaning to estrus was longer (P less than .05) for the hysterectomy group (10.4 +/- 1.6 d) than the control group (6.2 +/- .5 d). In the control group, the first estrous cycle (8.8 +/- .3 d) was shorter (P less than .01) than the second estrous cycle (20.2 +/- .5 d). Following first estrus in the hysterectomy group, cows were not detected in estrus until after injection of PGF2 alpha and did not return to estrus. From d 0 to 5, mean concentrations of plasma progesterone were similar (P greater than .05) between groups for both estrous cycles; after d 5 of estrous cycle 1, concentrations of plasma progesterone decreased in the control group. Within the hysterectomy group, the pattern of secretion of progesterone from d 0 to 16 was similar after the first and second estrus. Furthermore, there was no difference in the pattern of secretion of progesterone from d 0 to 16 between hysterectomy (first or second estrous cycles) and control (second estrous cycle) groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Anestrus↗
PubMed1987

A prospective, randomized study of 5-fluorouracil and filtration surgery.

Our study shows that use of a small dose of subconjunctival 5-FU provides significantly lower postoperative intraocular pressure than does no antimetabolite treatment. Morphology of the postoperative blebs suggests that increased filtration results in lower intraocular pressure in the 5-FU group. Corneal epithelial defects were as common with a low dose as with higher doses previously described.

Adolescent↗
PubMed1986

Mechanisms associated with subnormal luteal function.

Mechanisms associated with subnormal luteal function are reviewed with particular reference to sheep and cattle. Since the corpus luteum is a continuation of follicular maturation, mechanisms during both the follicular and luteal phase have been considered. During the follicular phase, extrafollicular and intrafollicular events are important for adequately preparing follicular cells for luteinization and secretion of progesterone (P4). Mechanisms which alter the microenvironment of the preovulatory follicle may impair the ability of follicular cells to subsequently secrete P4 and result in subnormal luteal function. During the luteal phase, secretion of P4 is probably dependent upon a balance between luteotropic and luteolytic stimuli. Subnormal luteal function may be due to an inadequate luteotropic stimulus and(or) an inability of luteal tissue to respond to a luteotropic stimulus. Additionally, a premature luteolytic stimulus may be involved in reduced luteal function. Specifically, premature luteolysis may result from an increased or premature release of a luteolysin or perhaps an increased responsiveness of luteal tissue to a luteolysin.

Animals↗
PubMed1986

Diagnosis and treatment of posterior urethral injury.

The initial investigation and diagnosis in 28 patients with posterior urethral trauma are presented. Twenty-five patients underwent either primary realignment for complete rupture or cystostomy alone for partial rupture. The results of their management are reported.

Adolescent↗
PubMed1986

Recent advances in corpus luteum physiology.

Development, maintenance, and regression of the corpus luteum have been investigated for many years. However, endocrine and cellular mechanisms regulating progesterone synthesis and secretion remain unclear. Because comprehensive reviews of factors affecting luteal function have been published recently, this paper discusses several emerging concepts that may be important in understanding the regulation of luteal progesterone synthesis and secretion. Concepts discussed include preovulatory follicular determinants of subsequent luteal function, hormonal stimulation of progesterone synthesis, effect of different luteal cell types on progesterone secretion, and role of secretory granules in luteal function.

Animals↗
PubMed1986

Autotransfusion, an experience of seventy six cases.

The use of autotransfusion with a centrifugal cell washer in a series of 76 cases is reviewed. The requirement for bank blood is reduced in patients with major operative haemorrhage, although it does not appear to be able to provide the main source of blood replacement in such cases. The major impact of autotransfusion may lie in reducing the amount of blood that needs to be crossmatched for elective operations. Nevertheless in certain cases its use can be life saving.

Blood Transfusion, Autologous↗
PubMed1985

Effects of 72 hr calf removal and/or gonadotropin releasing hormone on luteinizing hormone release and ovarian activity in postpartum beef cows.

A study was conducted to determine the pituitary and ovarian responses to 72 hr calf removal (CR) and/or gonadotropin releasing hormone (GnRH) in beef cows. Forty-eight Angus, Simmental, and Charolais crossbred cows in moderate body condition were allotted to an experiment of 2x2 factorial design involving CR and GnRH. At 30 to 32 days postpartum, calves were removed for 72 hr from the CR and CR plus GnRH groups. All cows were injected (i.m.) with saline or 200 microg of GnRH at 33 to 35 days postpartum. Saline or GnRH was injected 5 hr before calf return. Plasma luteinizing hormone (LH) was measured in blood samples collected every 30 min for 5.5 hr beginning 30 min prior to injection of saline or GnRH. Plasma progesterone was measured in blood samples collected 0, 7, and 14 days after GnRH injection and 7 and 14 days following the first detected estrus. There were no differences (P>0.05) in the interval to peak LH release or the magnitude of the LH release between the GnRH and CR plus GnRH groups; however, the GnRH induced release of LH was greater (P<0.05) over time when preceded by CR. Plasma progesterone concentrations were increased on day 7, compared to day 0, after GnRH injection in 57% and 50% of the animals in the GnRH and CR plus GnRH groups, respectively. However, behavioral estrus was not observed in any of the cows between days 0 and 7 after GnRH injection. A higher (P<0.05) percentage of the cows injected with GnRH formed luteal tissue compared to cows injected with saline; however, the luteal lifespan following GnRH injection was decreased relative to the luteal lifespan following the first observed estrus. The mean interval from calving to first estrus was decreased (P<0.05) by 17 days in the CR group relative to the other groups, and calf removal had no detrimental effect on milk production at 80 days postpartum or on calf weaning weights at approximately 7 months of age. In summary, 72 hr CR decreased the postpartum interval and increased the pituitary responsiveness to GnRH. Pretreatment with 72 hr CR did not alter circulating progesterone concentrations or luteal lifespan of corpora lutea induced by GnRH.

Journal Article↗
PubMed1985

The topical use of 5-fluorouracil in the ear in the management of cholesteatoma and excessive mucous secretion.

5-Fluorouracil was introduced in the early 1960s as a topical chemotherapeutic agent and has become increasingly accepted because of its efficacy, economy, and relative absence of side effects in treating many pre-cancerous conditions, certain benign and malignant tumors, and dermatoses. This paper addresses the use of topical 5-fluorouracil in the management of cholesteatoma and unwanted mucus-secreting cells. A retrospective study has suggested a very impressive efficacy of topical 5-fluorouracil in the management of cholesteatoma and, to a lesser degree, control of hyper-mucus-secreting cells at locations in the middle ear and mastoid. The use of topical 5-fluorouracil in the management of hyperkeratosis, cholesteatoma in the middle ear and mastoid, and in the external canal has been almost 100% effective with very few side effects. In the management of hyper-mucous-secreting cells, 5-fluorouracil has a success rate of approximately 50%.

Adolescent↗
PubMed1985

Effect of unilateral ovariectomy and injection of bovine follicular fluid on gonadotropin secretion and compensatory ovarian hypertrophy in prepuberal heifers.

A study was conducted to determine whether compensatory ovarian hypertrophy occurred in prepuberal heifers, and if so, could compensatory ovarian hypertrophy be prevented by injecting charcoal-extracted bovine follicular fluid (CFF). An additional objective was to determine the effect of CFF injections on follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations following unilateral ovariectomy (ULO). Thirty-one prepuberal Angus, Hereford, and Angus X Hereford heifers were assigned by weight and breed to the following groups: Control-saline injections (C), unilateral ovariectomy-saline injections (ULO) and unilateral ovariectomy-CFF injections (ULO-CFF). In group C, a sham operation was performed on d 0 and both ovaries were removed on d 7. In groups ULO and ULO-CFF, either the right or left ovary was removed on d 0 and the remaining ovary was removed on d 7. From d 0 to 7, each heifer received an injection (iv, 7 ml/injection) of saline or CFF every 12 h. Jugular blood samples were collected immediately before each saline injection from d 0 to 7 and analyzed for FSH and LH. Unilateral ovariectomy increased ovarian (P less than .08) and follicular fluid (P less than .05) weights compared with groups C and ULO-CFF; however, lyophilized ovarian weight was similar (P greater than .05) for all groups. Injections of CFF blocked the increase in ovarian and follicular fluid weight following ULO. The total number of visible follicles per ovary was similar for all groups; however in the ULO group there was an increase (P less than .01) in those 5 to 6 mm and greater than or equal to 9 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Effects of charcoal-extracted, bovine follicular fluid on gonadotropin concentrations, the onset of estrus and luteal function in heifers.

A study was conducted to determine the effect of charcoal-extracted, bovine follicular fluid (CFF) on plasma follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations, the interval from luteolysis to estrus, and subsequent luteal function in heifers. Fifteen Angus, Simmental and Hereford heifers were allotted by age, weight and breed to a control (C, n = 8) or a CFF (n = 7) group. Heifers received injections of saline or CFF (iv, 8 ml/injection) every 12 h from d 1 (d 0 estrus) through d 5 of the estrous cycle. On d 6, each heifer was injected (im) with 25 mg of prostaglandin F2 alpha (PGF2 alpha). Blood samples were collected every 12 h by venipuncture starting just before the first saline or CFF injection and continuing until estrus. Thereafter, blood samples were collected every other day during the subsequent estrous cycle and assayed for FSH, LH, estradiol-17 beta and progesterone by radioimmunoassay. Injections of CFF had no effect (P greater than .05) on circulating FSH or LH concentrations from d 1 to 5 relative to the C group; however, there was a transient rise (P less than .05) in FSH concentrations 24 h following cessation of CFF injections. This transient rise in FSH was not immediately followed by an increase in plasma estradiol-17 beta concentrations. Although CFF injections did not interfere with PGF2 alpha-induced luteolysis, the interval from PGF2 alpha injection to estrus was delayed (P less than .05) by 5 d in the CFF group compared with the C group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Changes and interrelationships among luteal LH receptors, adenylate cyclase activity and phosphodiesterase activity during the bovine estrous cycle.

Changes and interrelationships among the cellular mechanisms that may regulate luteal progesterone synthesis during the bovine estrous cycle were studied. Corpora lutea (CL) were enucleated from 30 cows via a transvaginal incision on d 4, 7, 10, 13, 16 and 19 following estrus (estrus = d 0). Mean corpus luteum weight, and luteal progesterone and plasma progesterone concentrations increased (P less than .05) from d 4 to 7 or 10, and declined following luteal regression (d 19). Unoccupied LH receptor (UOR) concentrations increased (P less than .05) more than fourfold from d 4 (38 fmol/mg protein) to d 16 (173 fmol/mg protein) before declining (P less than .05) by d 19 (30 fmol/mg protein). The dissociation constant for UOR concentrations increased (P less than .05) during the estrous cycle. Concentrations of occupied LH receptors (OR) were less (P less than .05) on d 7 than other days; however, the total number of OR/CL increased fourfold from d 4 (47 fmol/CL) to d 10 (221 fmol/CL) and remained similar thereafter. Basal adenylate cyclase, LH-activated adenylate cyclase, and Gpp(NH)p-activated adenylate cyclase activities were greatest (P less than .05) on d 7 to 16 as compared with d 4 and 19. Luteinizing hormone stimulated (P less than .05) adenylate cyclase activity relative to basal activity on d 7, 10, 13, and 16; whereas, Gpp(NH)p stimulated (P less than .05) adenylate cyclase activity relative to basal activity at each period. Phosphodiesterase was 46% greater on d 19 as compared with d 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1985

Conservation of hearing in acoustic schwannoma surgery.

Hearing conservation in acoustic schwannoma surgery is possible in approximately 50% of patients those 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 its superior exposure and less morbidity. An operating table capable of 35 degrees side rotation is used because it allows the majority of patients with acoustic neuromas 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 preservation of hearing. The carbon dioxide laser is a useful surgical tool with its properties of vaporization, cutting, and coagulation.

Carbon Dioxide↗
PubMed1984

Labeling suspended aerosol particles with short-lived radionuclides for determination of particle deposition.

Radiotracer techniques were developed to examine parameters that characterize pressurized aerosols designed to deliver insoluble particles suspended in the aerosol formulation. Microaggregated bovine serum albumin microspheres that were to be suspended were labeled with iodine-131 (t1/2 = 8 d). This iodination procedure (greater than 80% effective) is also applicable to iodine-123, which possesses superior characteristics for external imaging and further in vivo studies. This report shows that for pressurized aerosols containing suspended particles, each metered dose is approximately equal (not including the priming doses and the emptying doses). Increase in the delivery of the albumin particles out of the canister was best achieved by pretreating the valve assembly with a solution of 2% (w/v) bovine serum albumin in phosphate buffer. Use of a cascade impactor delineated the particle size distribution of the micropheres, with the majority of particles ranging in size from 2 to 8 microns. The data disclosed here indicate that the techniques developed with short-lived radionuclides can be used to quantitate each metered dose, characterize the particle size distribution profile of the aerosol contents, and determine the extent of deposition of the particles in the aerosol canister and all of its components.

Aerosols↗
PubMed1984

Biochemical investigations on a patient with a defect in cytosolic acetoacetyl-CoA thiolase, associated with mental retardation.

A severely mentally retarded boy with two normal siblings was persistently found to excrete elevated amounts of 3-hydroxybutyrate and acetoacetate. Enzyme analysis in cultured fibroblasts revealed a probable deficiency in cytosolic acetoacetyl-CoA thiolase which was about half the control activity with normal mitochondrial thiolase activities. Treatment with reduced dietary fat was initiated and a rapid reduction of the ketosis to biochemical normality was demonstrated. Shortly after initiating dietary treatment he presented with severe gastrointestinal problems and the histological features of colitis cystica superficialis. This appeared to respond to intravenous hydrocortisone therapy with an apparent complete recovery.

Acetyl-CoA C-Acetyltransferase↗