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Biomedical subjects

J F Smith

Publications and source records attributed to J F Smith.

At least 109 records · Page 6Linked to original sources
PubMed1992

Analysis and computations of measurement system effects in ultrasonic scattering experiments.

A model that characterizes the effects of beams and waveforms on the measurement of ultrasonic scattering is analyzed in detail. The analysis obtains a wideband expression for the system function in terms of an integration over spatial- and temporal-frequency variables. The temporal-frequency integration is reduced to a convolution in the direction of the scattering vector when the temporal frequencies are concentrated in a narrow band around a central frequency. The spatial-frequency integration is simplified to a straight line path when the spatial frequencies in the angular spectra of the emitter are concentrated around a point on the axis of the emitter and the spatial frequencies of the detector sensitivity pattern are similarly concentrated around a point on the axis of the detector. Expressions that result from the temporal and spatial approximations are evaluated analytically for circularly symmetric Gaussian spatial apertures and Gaussian temporal waveforms. In addition, numerical results are obtained to compare the effects of circularly symmetric Gaussian, exponential, and uniform spatial aperture functions on the weight that beam patterns have on measurements of scattering. The results may be used to design experiments from which intrinsic parameters of scattering media can be obtained by an appropriate normalization to remove measurement system effects from the data.

Humans↗
PubMed1992

Interleukin 6. A potential autocrine/paracrine factor in Paget's disease of bone.

Pagetic osteoclasts are greatly increased in number and size and have increased numbers of nuclei per cell compared to normal osteoclasts. The mechanisms responsible for enhanced osteoclast formation in Paget's disease are unknown. We have used our recently described model system for pagetic osteoclast formation to evaluate culture media conditioned by these atypical multinucleated cells (MNC) to determine if pagetic osteoclasts produce an autocrine or paracrine factor that enhances osteoclast formation. Conditioned media from long-term bone marrow cultures from patients with Paget's disease stimulated osteoclast-like MNC formation in normal marrow cultures. At least part of this activity could be ascribed to interleukin 6 (IL-6). In contrast, conditioned media from normal marrow cultures contained lower levels of IL-6 and did not stimulate formation of osteoclast-like MNC. 7 of 8 bone marrow plasma samples taken from involved bones and 18 of 27 peripheral blood serum samples from Paget's patients had high levels of IL-6. Normal marrow plasma and peripheral blood serum had no or very low levels of IL-6. These results suggest that IL-6 produced by marrow and/or bone cells in patients with Paget's disease may be an autocrine/paracrine factor for pagetic osteoclasts.

Biological Assay↗
PubMed1992

Effect of progesterone and oestradiol benzoate on oestrous behaviour and secretion of luteinizing hormone in ovariectomized fallow deer (Dama dama).

Eighteen ovariectomized fallow deer does and two adult bucks were used to investigate the effect of exogenous progesterone and oestradiol benzoate on oestrous behaviour and secretion of luteinizing hormone (LH). In Expts 1 and 2, conducted during the breeding season (April-September), does were treated with intravaginal Controlled Internal Drug Release (CIDR) devices (0.3 g progesterone per device) for 12 days and differing doses of oestradiol benzoate administered 24 h after removal of the CIDR device. The dose had a significant effect on the proportion of does that exhibited oestrus within the breeding season (P less than 0.001), the incidence of oestrus being 100% with 1.0, 0.1 and 0.05 mg, 42% for 0.01 mg and 0% for 0.002 mg oestradiol benzoate. There was a significant log-linear effect of dose on the log duration of oestrus, which was 6-20, 2-14, 2-12 and 2 h after treatment with 1, 0.1, 0.05 and 0.01 mg of oestradiol benzoate, respectively. Dose had a significant effect on the peak plasma LH concentration (P less than 0.01), mean (+/- s.e.m.) surge peaks of 27.7 +/- 2.3, 25.9 +/- 1.8 and 18.6 +/- 3.4 ng/ml being observed following treatment with 1, 0.1 and 0.01 mg oestradiol benzoate respectively. In Expt 3, also conducted during the breeding season, progesterone treatment (0 vs. 6-12 days) before the administration of 0.05 mg oestradiol benzoate had a significant effect on the incidence of oestrus (0/6 vs. 10/12, P less than 0.05), but not on LH secretion. The duration of progesterone treatment (6 vs. 12 days) had no effect on oestrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Relationship between the onset of oestrus, the preovulatory surge in luteinizing hormone and ovulation following oestrous synchronization and superovulation of farmed red deer (Cervus elaphus).

The timing of ovulation relative to the onset of oestrus and the preovulatory surge in luteinizing hormone (LH) was studied in red deer following treatments to synchronize oestrus and induce either a monovulatory or superovulatory response. Mature hinds (n = 36) were allocated randomly to two mating groups (n = 16 + 20), with respective treatments staggered by 4 weeks during the 1990 rut (March-April). Each hind was treated with an intravaginal controlled internal drug releasing (CIDR)-type S device for 14 days. Treatments to induce a monovulatory response included CIDR device alone (treatment A; n = 4 + 8) and additional injection of 200 iu pregnant mares' serum gonadotrophin (PMSG) at device removal (treatment B; n = 4 + 4). Treatments to induce a superovulatory response included injections of 200 iu PMSG and 0.5 units ovine follicle-stimulating hormone (FSH) at about time of removal of CIDR devices (treatment C; n = 4 + 4) and further treatment with gonadotrophin-releasing hormone (GnRH) analogue 18 h after removal of CIDR devices (treatment D; n = 4 + 4). The hinds were run with crayon-harnessed stags from insertion of CIDR devices (12 March or 9 April) and blood samples were taken every second day to determine plasma progesterone. Further blood samples were collected for determination of plasma LH and progesterone via indwelling jugular cannulae every 2 h for 72 h from removal of CIDR devices. Hinds were allocated randomly to an initial ovarian examination by laparoscopy at either 16 or 20 h (A and B), or 12 or 16 h (C and D) after the onset of oestrus, with laparoscopy repeated at intervals of 8 h until either ovulation was recorded (A and B), or for four successive occasions (C and D). All hinds received cloprostenol injections 15 days after device removal. A total of 28 hinds (78%) exhibited oestrus and a preovulatory LH surge, with mean (+/- SEM) times to onset of oestrus of 44.6 +/- 1.0 h (A; n = 7), 37.4 +/- 2.0 h (B; n = 7), 16.3 +/- 1.7 h (C; n = 6) or 14.0 +/- 1.7 h (D; n = 8). Failure to exhibit oestrus or LH surge was most prevalent among hinds in treatment A early in the rut.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Short-acting beta-adrenergic blockade and the fetus. A case report.

An infant was born to a woman who received intravenous esmolol for intrapartum supraventricular tachyarrhythmia. Despite the very short acting and cardio-selective beta-1 adrenergic blockade induced by that agent, neonatal effects can occur up to 48 hours after delivery.

Adrenergic beta-Antagonists↗
PubMed1992

The biophysical profile and the nonstress test: poor predictors of chorioamnionitis and fetal infection in prolonged preterm premature rupture of membranes.

Sixty-eight women admitted with the diagnosis of preterm premature rupture of membranes (PROM) and a latency period of at least 48 hours were followed expectantly. Fetal surveillance consisted of daily kick counts, daily nonstress test (NST), and fetal biophysical profile every 48-72 hours. Patients were delivered as a result of spontaneous labor, clinical chorioamnionitis, fetal distress, or attainment of 37 weeks' gestation. No corticosteroids, tocolytics, or prophylactic antibiotics were used. The last biophysical profile and the last NST before delivery were evaluated for each patient. There was no statistically significant association between chorioamnionitis or fetal infection and the following: 1) a low biophysical profile (score of 6 or lower), 2) a low biophysical profile that included a nonreactive NST and absent fetal breathing movements, or 3) a nonreactive NST. We conclude that the biophysical profile and the NST are poor predictors of perinatal infectious complications.

Adolescent↗
PubMed1991

Structural elements in the N-terminal half of transcription factor IIIA required for factor binding to the 5S RNA gene internal control region.

Zinc binding domains and the conserved Thr-Gly-Glu-Lys (TGEK) tetrapeptide in the N-terminal half of transcription factor IIIA (TFIIIA) were subjected to in vitro mutagenesis to biochemically assess their role in factor interaction with the 5S gene internal control region (ICR). TFIIIA containing a Leu in place of His33 in the Cys2His2 zinc binding site of finger I lost the ability to protect the entire 5S RNA gene ICR (nucleotides +96 to +43) from DNase I digestion. Thus, mutation of one potential zinc ligand in the N-terminal finger inhibited specific DNA binding by the N-terminal as well as downstream fingers. Cooperativity apparently exists among TFIIIA zinc fingers in metal binding/finger folding and DNA binding. Substituting a Ser for Gly69 or a Glu for Lys 71 in the conserved TGEK tetrapeptide in finger II of TFIIIA resulted in the loss of DNA binding. A Gly-dependent bend structure and a terminal positive charge in this tetrapeptide are important for TFIIIA interaction with DNA. Whereas TFIIIA with a Ser substituted for Cys20 in finger I (proposed zinc ligand) did not protect the ICR from DNase I digestion, TFIIIA containing a Ser substituted for Cys35 (not a proposed zinc ligand) retained the ability to bind the ICR. When Cys112 or Cys 164 (proposed zinc ligands in fingers IV and VI) were replaced by Ser, the DNase I footprint patterns afforded by the respective mutant proteins were similar, protection on the ICR from about nucleotides +96 up to +78. A similar pattern was obtained with a TFIIIA mutant in which fingers V, VI, VII, and a portion of VIII were deleted. Maintenance of zinc coordination spheres in necessary for DNA binding by downstream fingers. The six fingers comprising the N-terminal half of TFIIIA appear to act in two groups of three with binding of the second group dependent upon initial binding of the N-terminal group to the +90 to +80 region of the 5S gene ICR.

Amino Acid Sequence↗
PubMed1991

Role of hepatocytes and Kupffer cells in age-dependent murine hepatitis caused by a phlebovirus, Punta Toro.

Punta Toro virus (PTV) infection of C57BL/6 mice results in fulminant hepatic necrosis and death in 3-week-old susceptible mice, but survival with minimal hepatocellular necrosis in 8-week-old resistant mice. Susceptibility in 3-week-old mice is associated with an earlier rise of viral titers in liver and serum than that occurring in 8-week-old resistant mice. There is also an earlier and more rapid accumulation of infectious progeny in serum vs. liver after PTV infection in both age groups, suggesting that the virus may replicate in extrahepatic sites as well as the liver. PTV infection of isolated hepatocytes and Kupffer cells from 3- and 8-week-old mice demonstrates a significant age-related difference in the ability of these cells to support replication of PTV in vitro (P less than 0.05). The age-related difference in liver cell-PTV interaction appears to be an inherent difference in the liver cells themselves, since there are no age-related differences in viral adsorption, morphogenesis, cytopathic effect, or interferon action within these cells. Thus, age-related differences in PTV replication or dissemination at extrahepatic sites, and the ability of the virus to replicate in intrahepatic sites, may be additive factors in the expression of age-related susceptibility to PTV in C57BL/6 mice.

Aging↗
PubMed1991

Attenuating mutations in the E2 glycoprotein gene of Venezuelan equine encephalitis virus: construction of single and multiple mutants in a full-length cDNA clone.

Attenuated mutants of Venezuelan equine encephalitis virus (VEE) were isolated by selection for rapid penetration of cultured cells (R. E. Johnston and J. F. Smith, 1988, Virology 162, 437-443). Sequence analysis of these mutants identified candidate attenuating mutations at four loci in the VEE E2 glycoprotein gene: a double mutation at E2 codons 3 and 4, and single substitutions at E2 76, 120, and 209. Each candidate mutation was reproduced in an isogenic recombinant VEE strain using site-directed mutagenesis of a full-length cDNA clone of VEE. Characterization of these molecularly cloned mutant viruses showed that mutation at each of the four loci in the E2 gene was sufficient to confer both the accelerated penetration and attenuation phenotypes. Inoculation of the molecularly cloned viruses into rodent models that differ in their response to VEE suggested that individual mutations affected different aspects of VEE pathogenesis. Full-length clones containing multiple mutations were produced by combining independently attenuating mutations. Molecularly cloned viruses carrying two or three mutations were more attenuated in sensitive animal models than viruses which contained any single mutation alone. However, these highly attenuated strains still retained the ability to induce an immune response sufficient to protect against a high dose challenge with virulent VEE. These results indicate that production of a molecularly cloned live virus vaccine for VEE is feasible.

Animals↗
PubMed1991

The effects of collection and processing procedures on post-thaw bovine spermatozoan characteristics.

Thirty-two ejaculates from four Holstein bulls were utilized in the study. Neat semen was diluted (1:10) with 20% egg yolk-citrate and cooled to 5 degrees C within either 0.5 or 3 h, then glycerolated, and equilibrated for 2 h. Straws were frozen over liquid nitrogen, stored at -196 degrees C, and thawed at 46, 37, or 23 degrees C for 12, 20, or 60 sec, respectively. The average percentages of progressive motility and unstained cells post thawing increased (34.5 vs 31.4%; P<0.01 and 41.9 vs 37.1%; P<0.002, respectively) for semen collected in polyethylene rather than in rubber liner-collection cones. The post-thaw mean progressive motility for spermatozoa cooled to 5 degrees C within 3 vs 0.5 h was higher (34.5 vs 31.5%; P<0.0001, respectively). Similar differences were observed for unstained cells (40.7 vs 38.2%; P<0.0001, respectively). Mean acrosomal scores were lower when cells were collected in polyethylene (1.00 vs 1.03; P<0.02) and also when a 3-h cooling period was used (1.01 vs 1.03; P<0.0001). Spermatozoa thawed at higher temperatures exhibited increases (P<0.0001) in both progressive motility and the percentage of unstained cells. The average percentages of progressive motility and unstained cells were 37.1, 35.7 and 26.1% and 43.4, 41.5 and 33.5%, respectively, at thawing temperatures of 46, 37 and 23 degrees C. Based on the results of this study, optimal conditions for bovine semen handling were the collection of semen in polyethylene liner-collection cones, preglycerolation cooling within 3 h, and thawing at 46 degrees C for 12 sec.

Journal Article↗
PubMed1991

Studies on the role of liver cytochrome P-450 and oestradiol metabolism in the effects of nutrition and phenobarbital on ovulation rate in the ewe.

Coopworth ewes were differentially fed to produce 60 heavy (62 kg) and 80 light (45 kg) ewes. They were then fed a low protein (100 g protein kg-1 dry matter) pelleted ration. On Day 7 of the oestrous cycle after synchronization the following treatments were commenced in groups of 10 ewes: 4 low liveweight groups received low protein (LP), high protein (HP; 230 g protein kg-1 dry matter), LP + phenobarbital (PB; 1 g per os per day in gelatin capsules for 10 days) and LP + triacetyloleandomycin (TAO, 0.5 g day-1 in capsule for 10 days); while 3 high liveweight groups received LP, HP and HP + carbon tetrachloride (CCl4, 0.1 mL kg-1 bodyweight as a single dose). The experiment was repeated using another 7 groups of 10 ewes at an interval of 3 weeks. PB, TAO, high liveweight, and protein diet increased the ovulation rate whereas treatment with CCl4 reduced the ovulation rate. Because of the small number of ewes in some treatment protocols, only changes due to liveweight and protein diet were statistically significant. Liver weight and microsomal protein were increased by all treatments except CCl4 which caused a decrease. PB and TAO increased cytochrome P-450 and associated enzyme activities, in particular those related to cytochrome P-450p or P-450NF (including oestradiol 2-hydroxylation) in the human liver. In vitro, TAO binding indicated that the specific cytochrome was induced by PB and TAO but there were no direct effects of protein diet and liveweight. Most of the data support the theory that nutritionally induced increases in ovulation rate in ewes could result from changes in oestradiol metabolism, but the lack of induction of the specific cytochrome by protein diet and high liveweight suggests that increased ovulation caused by these factors may be the physiological response to several metabolic changes.

Animal Nutritional Physiological Phenomena↗
PubMed1991

Risks and benefits of laparoscopic cholecystectomy in the community hospital setting.

Laparoscopic cholecystectomy has rapidly become more popular than open cholecystectomy. To further evaluate the safety and efficacy of laparoscopic cholecystectomy in the community setting, the first 190 patients to undergo the procedure in Saginaw, Michigan were studied. There were 159 females and 31 males. The mean age was 47.8 years. All patients had symptoms consistent with biliary tract disease and most had gallstones proven by preoperative ultrasound. The mean operative time was 84 minutes but decreased from 161 minutes the first month of the study to 74 minutes by the seventh month. Eighty-seven percent of patients were tolerating a regular diet by postoperative day 1. Ninety-six percent of patients were requiring only oral pain medications by postoperative day 1. Seventy percent of patients were discharged by postoperative day one while 91% were discharged by postoperative day 2. Six patients were converted to open cholecystectomy due to acute inflammation, significant bleeding or extensive adhesions. There were no deaths and the morbidity rate was 9.5%. The most significant complication was postoperative bile leak which occurred in two patients. Patients returned to work a mean of 16.1 days following surgery and to their normal daily activities at home a mean of 12.9 days postoperatively. This study of the first 190 laparoscopic cholecystectomies in Saginaw affirms the safety and feasibility of this procedure in the community setting in selected patients.

Biliary Tract Diseases↗
PubMed1991

Evaluation of fetal sonographic measurements in the first trimester by transvaginal sonography.

To assess the reliability of early biometric measurements in pregnancy, transvaginal sonography was performed in 92 pregnancies in the first trimester in a cross-sectional fashion. Measurements included crown-to-rump length (CRL), biparietal diameter (BPD), head and abdominal circumference (HC and AC), and femur length (FL). Stepwise regression analysis of the gestational age was performed. CRL maintained the highest correlation with gestational age (r = 0.99, p less than 0.001). BPD, HC, AC also correlated well. FL showed a less strong correlation with gestational age (r = 0.76, p less than 0.001). CRL remains the standard for early sonography measurements.

Embryonic and Fetal Development↗
PubMed1991

Pathogenesis of Venezuelan equine encephalitis virus infection in mice and hamsters.

The pathogenesis of Venezuelan equine encephalitis (VEE) virus infection was compared in intraperitoneally inoculated mice (n = 24, 6 to 8 weeks old) and hamsters (n = 9, 90-110 g) using histopathology and immunohistochemical localization of VEE virus antigen. Infected mice developed paralysis, and the majority died by 9 days after inoculation. In contrast, hamsters did not survive beyond 3 days after inoculation, and they did not develop any neurologic signs. VEE virus antigen, demonstrated by immunoperoxidase staining, and pathologic changes were present in extraneural organs of both mice and hamsters. There was more severe involvement in hamsters, particularly in Peyer's patches of the distal small intestine. There was a severe encephalomyelitis in mice, but pathologic changes were not well established in the brains of hamsters before death. VEE virus antigen was widespread in the central nervous system of both mice and hamsters. VEE virus was found to be highly neurotropic in hamsters and had a similar distribution in the brain as in mice, but hamsters died from their extraneural disease before major central nervous system disease developed.

Animals↗
PubMed1991

Liner collection cone and pH effects on postthaw motility, staining, and acrosomes of bovine spermatozoa.

Sixteen ejaculates were collected, four each from four bulls, using artificial vaginas with polyethylene or rubber liner collection cones in a crossover design experiment. The ejaculates were diluted with egg yolk-citrate extender at pH 6.4 or 7.2, cooled, glycerolated, equilibrated, packaged in .5-ml French straws, frozen in nitrogen vapor, and stored in liquid nitrogen. Thirty frozen straws from each ejaculate were thawed rapidly (46.5 degrees C for 12 s), pooled, and then incubated at 46.5 degrees C for periodic evaluation of progressive motility, differential staining, and acrosome morphology under thermal stress conditions. The postthaw motility of spermatozoa and percentage of unstained cells were higher both when collected in polyethylene than in rubber and when extended at pH 7.2 vs. 6.4, but no interaction was found between liner collection cone composition and pII for postthaw motility. Retention of spermatozoan motility during incubation under thermal stress was greater for cells collected in polyethylene, but not different due to pH. Neither pH nor composition of liner collection cone had an effect on postthaw acrosomal scores, but the time required for a 50% increase in severely damaged acrosomes was greater for spermatozoa collected in polyethylene than in rubber liner collection cones.

Acrosome↗
PubMed1991

Limitations to heavy work at 21 degrees C of personnel wearing the U.S. military chemical defense ensemble.

The purpose of this study was to determine the limitations to work of personnel performing heavy work at 21 degrees C (70 degrees F) while wearing the chemical defense ensemble (CDE) worn by all branches of the U.S. military. Male volunteers (N = 17) wearing the CDE performed an arm and leg work task yielding a time-weighted energy consumption rate of 450 W, under environmental conditions of 21 degrees C and 65-70% relative humidity. Each work bout was continued until one of the following limits occurred: volitional fatigue, rectal temperature (Tre) of 39 degrees C, or calculated heat storage (S) of 140 Wh. Subjects then rested until heat stored due to this work was lost, then repeated the work-rest cycles until refusal, or inability to restart work after a rest cycle. Over a total of 36 work cycles, subjects terminated work cycles for S on only two occasions, with the remainder almost equally divided between cumulative fatigue and high Tre. Intersubject variability was high for work and rest times, S, heat loss, and sweat production. U.S. Air Force Regulation (AFR) 355-8, which provides guidance for heat stress in the form of work/rest cycles, underestimated work tolerance under these study conditions.

Adult↗