Biomedical subjects

A J Peters

Publications and source records attributed to A J Peters.

At least 37 records · Page 2Linked to original sources

PubMed1996

Vibroacoustic stimulation with a complex signal: effect on behavioral state in fetal sheep.

An ideal vibroacoustic stimulus for testing fetal reactivity has yet to be developed. In the present study in fetal sheep we tested the effect on behavioral state of an amplitude and frequency-modulated signal produced at the abdominal surface of the ewe. The stimulus was presented during periods of fetal non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Evaluation of behavioral state was accomplished by visual observation of strip-chart recordings. Assessed in this manner, vibroacoustic stimulation during NREM sleep consistently resulted in a change to an indeterminate state. However, stimulation during REM sleep failed to have an effect. Additional evaluation applying spectral analysis to the fetal electrocorticogram during stimulation in NREM sleep revealed a marked decrease in delta band power from 100 to 27 +/- 5% and in theta band power from 100 to 40 +/- 4% resulting in a decrease in total power from 100 to 35 +/- 4% (p < 0.05). Stimulation during REM sleep revealed a significant increase in beta band power from 100 to 123 +/- 14%. Vibroacoustic stimulation in both NREM and REM sleep led to an increase in spectral edge frequency, implying central arousal.

Acoustic Stimulation↗

PubMed1995

Fetal acoustic stimulation test: stimulus features of three artificial larynges recorded in sheep.

OBJECTIVE: The purpose of the current study was to evaluate the characteristics of vibroacoustic devices used for fetal stimulation. STUDY DESIGN: Intrauterine sound pressure levels over a frequency range of 40 to 5000 Hz were measured with hydrophones in anesthetized sheep. Stimulators included the AT&T (Martinsburg, W.V.) and Servox (Hearing Instruments, Piscataway, N.J.) artificial larynges, the Corometrics fetal acoustic stimulator (Wallingford, Conn.) and electric toothbrush. RESULTS: Intrauterine spectral patterns resulting from stimulation with the AT&T, Servox, and Corometrics devices were characterized by numerous high-level overtones above a fundamental frequency between 97 and 163 Hz. Fundamental frequencies recorded during toothbrush stimulation were 22 to 24 Hz with reduced but identifiable overtones up to 250 Hz. CONCLUSIONS: Fetal vibroacoustic stimulators that operate on the principle of the electronic artificial larynx produce very similar intrauterine sound pressure levels.

Acoustic Stimulation↗

PubMed1995

Fetal behavioral state patterns during and after prolonged exposure to cocaine in sheep.

OBJECTIVE: Studies on the effects of cocaine in fetal animals have been limited to acute exposures to the drug. We hypothesized that a prolonged infusion of cocaine to the fetal sheep would initially interrupt normal behavioral state cycling but the effects would be short lived as the fetus gained tolerance to the drug. STUDY DESIGN: The study was performed in a university laboratory on six time-dated pregnant ewes at 125 days' gestation. Fetal sheep, surgically instrumented 3 days before study, were given cocaine hydrochloride 0.6 mg/min for 6 hours. Fetal behavioral state before, during, and after the infusion was compared by repeated-measures analysis of variance. RESULTS: Infusion of cocaine caused a drop in the percentage time that the fetuses spent in both rapid-eye-movement (p < 0.03) and non-rapid-eye movement (p < 0.001) sleep, which was sustained throughout the 6-hour infusion. This was related to a decrease in the number of rapid-eye-movement and non-rapid-eye-movement episodes as opposed to a decrease in the lengths of these behavioral states. With cessation of cocaine infusion, the fetal sheep showed an increase in rapid-eye-movement sleep, with a higher percentage than during control periods (p < 0.02). CONCLUSIONS: Cocaine disrupts fetal rapid-eye-movement sleep without evidence for tolerance to the drug over a 6-hour period. "Catch-up" rapid-eye-movement sleep occurs with cessation of cocaine infusion. Neurobehavioral abnormalities associated with in utero cocaine exposure may be caused by chronic disruption of rapid-eye-movement sleep.

Analysis of Variance↗

PubMed1995

Estrogenic and antiestrogenic activities of anordiol: a comparison of uterine and vaginal responses with those of clomiphene citrate.

Anordiol (2 alpha,17 alpha-diethynyl-A-nor-5 alpha-androstane-2 beta,17 beta-diol) has been variously characterized as an estrogen and as an antiestrogen. To more completely understand the pharmacological properties of this contraceptive steroid, simultaneous responses were studied in uterine, vaginal, and hepatic tissues. Rats received 4 daily sc injections with either anordiol, clomiphene citrate (CC), or the vehicle alone (C+) starting on the first day of pseudopregnancy. Uteri were traumatized on day 4 of pseudopregnancy, and rats were sacrificed 5 days later. A pseudopregnant group without uterine trauma served as a negative control (C-). Mean uterine weights per animal and cytosolic estrogen (EcR) and progesterone (PcR) receptor activities per g of DNA were all 5- to 7-fold greater in the C+ group than in the other groups (all p < 0.05). However, anordiol and CC suppressed uterine weight without suppressing the stromal proliferative response; the DNA content of the uteri of anordiol- and CC-treated rats was similar to that of C+ rats. Vaginal tissue exhibited estrogenic responses to anordiol and CC with an increase in epithelial stratification compared to the C+ and C- groups even though no difference in levels of EcR/g of DNA were expressed 5 days after the last antiestrogen dose. Binding affinities and serum E2 and progesterone (P) concentrations were not statistically different among the groups. In conclusion, anordiol produced responses in the uterus and vagina of the pseudopregnant rat which were indistinguishable from those of CC, and, therefore, we conclude that anordiol acts on these tissues as an antiestrogen.

Animals↗

PubMed1995

Variation in antisperm antibody results using different assays.

PROBLEM: The detection of various types of antisperm antibodies (ASA) in the serum varies among different assays. This variation may influence the diagnosis and management of infertile couples who are tested for such immunologic factors. This prospective study was conducted to determine the variation in the results of ASA as measured by the sperm immobilization (SI), sperm agglutination (SA), and the indirect immunobead (IB) assays. METHOD: The sera of 79 patients that tested positive for ASA by at least one of the assays listed above were concurrently tested with all three assays. RESULTS: Using an individual ASA assay, 66 (84%), 26 (33%) or 36 (46%) of sera tested positive by the SA, SI, or IB assays, respectively. However, using a combination of assays, 67 (85%), 78 (99%) or 40 (51%) of sera tested positive using either the SA+SI, SA+IB or SI+IB assays, respectively. CONCLUSION: These findings suggest that the utilization of different assays to detect ASA may detect sera that are positive for ASA with more reliability than single assay testing.

Agglutination Tests↗

PubMed1994

Pharmacokinetics and pharmacodynamics of anordrin (2 alpha, 17 alpha-diethynyl-A-nor-5 alpha-androstane-2 beta, 17 beta-diol diproprionate).

In order to determine the pharmacokinetics of anordrin a dose of 0.2 mg/kg of [3-14 C]anordrin was administered i.v. to 5 cynomolgus monkeys; the same monkeys received the same dose i.m. at a later date. An additional 3 monkeys received 1.0 mg/kg of [3-14C]anordrin i.m. After administration of the compound, the dipropionate esters of anordrin were rapidly hydrolyzed to the dihydroxy parent compound, anordiol. After i.v. administration, anordrin had a mean residence time (MRT) of 5.0 +/- 1.3 (SE) min. [14C]Anordiol formed from [14C]anordrin had an MRT of 139 +/- 27 (SE) min. The metabolic clearance rates (MCR) of anordrin and anordiol were 55 and 34 mL/min.kg, respectively. The apparent volume of distribution at steady state (Vss) for anordrin was 276 mL/kg, 7.5% of body weight of the animals; anordrol had a much larger Vss of 4460 mL/kg. The MRT of anordiol after i.m. administration of 1.0 mg/kg of [14C]anordrin was 26.3 days. An average of 44% of the dose appeared in urine regardless of the route of administration or dose. The MRT values of total radioactivity were the same when calculated from serum or urine after an i.v. dose, but after i.m. administration, values from urine were approximately 60% of that calculated from serum, indicating that products appearing in urine had a shorter MRT than products appearing primarily in feces. A separate group of monkeys was given anordrin i.m. in doses ranging from 0.1 to 0.4 mg/kg on the first day of menses. The regression of length of menstrual cycle on dose was significant (P = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Noise induced hearing loss in fetal sheep.

The auditory brainstem response (ABR) was recorded in utero from chronically instrumented fetal sheep prior to and following exposure of pregnant ewes to intense broadband noise (120 dB SPL for 16 h). ABRs were elicited by clicks and tone bursts (0.5, 1, 2, and 4 kHz) delivered through a bone oscillator secured to the fetal skull. Latency-intensity functions for most of the four vertex-positive waves (labelled I-IV) were prolonged and ABR thresholds were temporarily elevated by an average of 8 dB following the noise exposure. Results show that exogenous sounds can penetrate the uterus and result in alterations of the fetal ABR.

Acoustic Stimulation↗

PubMed1994

Effect of impulse noise on the auditory brainstem response of the fetal sheep and the adult ewe: case study.

Auditory brainstem responses (ABR) were obtained from a sheep fetus in utero and from a nonpregnant ewe before and after a noise exposure generated by 10 105-mm howitzer impulses (160-166 dB peak pressure). Fetal ABR thresholds shifted by less than 15 dB, whereas the adult thresholds shifted more than 50 dB. Comparison of exposed and nonexposed fetal cytocochleograms revealed minimal sensory cell loss in two age-matched animals. Although fetal ABR threshold shifts were noted in this study, the magnitude of shift was modest when compared to the significant elevation of the adult ABR thresholds.

Acoustic Stimulation↗

PubMed1993

Three-dimensional intraabdominal sound pressures in sheep produced by airborne stimuli.

OBJECTIVE: Our aims were to investigate how airborne sound was distributed within the abdominal cavity of sheep as function of frequency. STUDY DESIGN: Airborne broad-band noise was measured with a hydrophone at 45 locations within the abdomen of five nonpregnant sheep post mortem and with a microphone extraabdominally. Sound pressure attenuation provided by the abdomen and its contents was determined for frequencies between 50 and 5000 Hz. An analysis of variance was applied to assess the effects of frequency, hydrophone location, and animal on intraabdominal distribution of sound pressures. RESULTS: Below 250 Hz sound pressure was higher inside the animal than outside. Little attenuation (< 10 dB) was found for sounds > 3000 Hz. Attenuation was greatest in the center of the abdomen and least along the inner margin of the abdomen. Intraabdominal sound pressure level varied with frequency (p < 0.0001) and with position of the hydrophone in the cross-sectional plane (p < 0.005) but not in the sagittal plane (p = 0.51). There was no animal effect (p = 0.18). CONCLUSION: During maternal exposure to airborne, broadband noise the fetus could be subjected to intense sound pressures at low frequencies regardless of position within the uterus and at high frequencies when positioned near the abdominal surface.

Abdomen↗

PubMed1993

Comparison of the methods of artificial insemination on the incidence of conception in single unmarried women.

OBJECTIVE: To compare pregnancy rates after intrauterine insemination (IUI) versus pericervical insemination in absolute male factor infertility using each patient as her own control. DESIGN: Ovulatory women with patent fallopian tubes without male partners were alternately inseminated with cryopreserved donor semen using either IUI or pericervical insemination techniques. A total of 81 cycles, which included up to 4 cycles per patient were performed. In this manner a comparison between the efficacy of each method could be evaluated. SETTING: The donor insemination program at the Center For Assisted Reproduction at Northwestern University Medical School. PATIENTS: Twenty-six single, healthy, unmarried women with patent fallopian tubes and < 40 years of age without male partners (absolute male factor infertility). MAIN OUTCOME MEASURES: Positive quantitative serum subunit of human chorionic gonadotropin followed by the presence of an intrauterine gestational sac seen by transvaginal ultrasonography. RESULTS: Fourteen (54%) of 26 patients conceived including two (14%) miscarriages within four insemination cycles. Seven (17.5%) patients after IUI, and 7 (17.1%) patients after pericervical insemination conceived. The pregnancy rates were similar regardless of the order of insemination method. CONCLUSION: These findings reveal that there is no statistical difference in the pregnancy outcome between these two methods of insemination in absolute male factor infertility.

Adult↗

PubMed1993

Quality assurance for sperm concentration using latex beads.

OBJECTIVE: To provide a simple, universally applicable method of quality assurance for sperm counting, thereby reducing intercounting chamber variation. DESIGN: By using a known concentration of latex beads, the sperm:bead ratio can be used to calculate the actual sperm count. MAIN OUTCOME MEASURES: The mean sperm and bead counts were determined in both a Spot-lite hemocytometer (Baxter Diagnostics, McGaw Park, IL) and a Makler chamber (Polymedco Inc., Yorktown, NY) from 21 different ejaculates mixed with a known concentration of beads. The hemocytometer chamber was used as the standard counting chamber because it consistently yielded a low variation in sperm count. The adjusted sperm concentration of the Makler chamber was calculated using the following formula [hemocytometer beads]/[Makler beads] x [Makler sperm]. RESULTS: Observed mean +/- SD sperm counts were significantly different between the hemocytometer chamber (110.6 +/- 66.2 x 10(6)/mL) and Makler chamber (173.3 +/- 103.5 x 10(6)/mL). However, calculated Makler chamber sperm counts (118.1 +/- 76.1 x 10(6)/mL) was not statistically different from observed hemocytometer sperm counts. CONCLUSION: This novel approach to sperm counting using a known concentration of latex beads as a reference material can be used to reduce variation in sperm counting between observers, counting chambers, and possibly computerized sperm analyzers.

Equipment and Supplies↗

PubMed1993

Colour Doppler ultrasound guidance for transcervical wire tuboplasty.

To evaluate the usefulness of high-resolution ultrasound with colour Doppler mapping system in performing transcervical wire tuboplasty, 13 infertile women with bilateral proximal tubal obstruction demonstrated by X-ray or colour Doppler ultrasound hysterosalpingography and chromoperturbation at laparoscopy were treated by transcervical wire tuboplasty utilizing colour Doppler mapping ultrasound guidance. A co-axial catheter was used to introduce a 0.016-in. flexible wire to the occluded portion. Transcervical wire catheterization was accomplished in 25 of 26 tubes (96%), resulting in patency in 24 of 25 tubes (96%). At the end of the procedure all patients had at least one tube patent (100%). Five (38%) women achieved pregnancies within 1 year after the procedure. High-resolution ultrasound with colour Doppler mapping system is an efficacious way to perform transcervical wire tuboplasty, avoiding the risk of radiation and allergic reaction.

Adult↗

PubMed1993

Abdominal vibration alters sleep state in fetal sheep.

Many pregnant women are exposed to low frequency sounds and vibrations while at work or play. How the fetus is affected by these physical stimuli is not clearly documented. We recorded behavioral state and intrauterine sound pressure levels in eight fetal sheep previously instrumented with electrocortical, electroocular and neck electromyographic leads, and with a miniature hydrophone. Data were collected before, during and after 30 min of abdominal vibration using a belt vibrator commonly used by humans in weight reduction programs. A sudden shift in behavioral state occurred at the onset of vibration. There was a decrease in non-rapid eye movement sleep (P < 0.02) and an increase in time during which the sleep state could not be determined (P < 0.03). A 63% increase in number of epochs spent in this indeterminate period was evident during vibration. During the post-stimulus period, percentage of time spent in rapid eye movement sleep decreased as compared to the pre-stimulus period (P < 0.04), and non-rapid eye movement sleep increased as compared to the stimulus period (P < 0.01). Vibration-induced intrauterine sound pressures ranged from 131-142 dB at the fundamental frequency of 19 Hz and were 20-40 dB lower at the overtones which appeared in the spectrum between 35-200 Hz. Results indicated that environmental vibration can disrupt fetal behavioral state, induce abnormal state changes, and alter distribution of sleep states.

Acoustic Stimulation↗

PubMed1993

Vibroacoustic stimulation in fetal sheep: effect on cerebral glucose utilization and behavioral state.

Behavioral state and cerebral glucose utilization were measured in six fetal sheep subjected to high intrauterine sound pressures created with a vibroacoustic stimulator pressed against the maternal abdomen. The signal consisted of a complex waveform that varied over time with a 50% duty cycle. An implanted hydrophone showed highest spectral levels between 3,000-16,000 Hz. The pulsed sound resulted in a significant loss of fetal rapid eye movement and non-rapid eye movement sleep. The stimulus also resulted in a disruption in the normally close relationship between these sleep states and cerebral glucose utilization rates in the brain as a whole and in its component parts.

Acoustic Stimulation↗

PubMed1993

Fetal vibroacoustic stimulation test: vibrator response characteristics in pregnant sheep postmortem.

OBJECTIVE: To determine the effect of small decreases in battery voltage on the sound pressure level and spectral features of sound within the uterus during vibroacoustic stimulation with a battery-powered electronic artificial larynx. METHODS: In eight pregnant, recently sacrificed sheep, the fluid-borne, intra-amniotic sound pressures resulting from vibration of the abdominal wall with an electronic artificial larynx were compared with airborne sound pressures produced by an artificial larynx and measured at 50 cm. RESULTS: At all frequencies, the intrauterine sound pressure was higher than the sound pressure in air. Decreasing battery voltage from 9 to 7 V resulted in a 5-18-dB decrease in intrauterine sound pressure at the electronic artificial larynx fundamental frequency and most overtones, but only a 4-8-dB decrease in the airborne signal. The results indicate that for frequencies relevant to fetal hearing, the reduction of sound pressure level caused by inadequate battery voltage may result in a difference in fetal response. CONCLUSION: Routine verification of the function of a vibroacoustic device by means of a battery voltage check is recommended.

Acoustic Stimulation↗

PubMed1993

Salpingitis or oophoritis: what causes fever following oocyte aspiration and embryo transfer?

BACKGROUND: Febrile morbidity following in vitro fertilization and embryo transfer (IVF-ET) is a rare but possibly serious complication. This report describes a case of salpingitis after IVF-ET and discusses the possible reasons for febrile morbidity following this common procedure. CASE: A 37-year-old woman undergoing IVF-ET for tubal factor infertility developed sudden, severe pelvic pain, fever, and leukocytosis 24 hours after ET. Laparoscopy revealed bilateral suppurative pyosalpinges with cystic, hemorrhagic ovaries. Pain, fever, and leukocytosis resolved with conservative surgery and intravenous antibiotic therapy. CONCLUSIONS: This case presents laparoscopic documentation of a rare complication of oocyte aspiration and/or ET, namely, salpingitis. Possibilities for the development of salpingitis following IVF-ET include activation of quiescent bacteria within the fallopian tubes from a previous pelvic infection, puncture of the bowel during oocyte aspiration, inoculation of the pelvis with cervicovaginal flora during oocyte aspiration, and introduction of bacteria-laden secretions or air into the fallopian tubes during ET. Although rare, the possibility of severe pelvic infection following IVF-ET warrants consideration of prophylactic antibiotic coverage.

Adult↗

PubMed1992

Effect of cocaine on electrocortical activity in fetal sheep.

The effect of cocaine on the behavioral state of six fetal sheep was studied during gestational ages between 128-135 days. Two to eight days after surgery, fetuses received either a continuous 60 min intravenous infusion of cocaine HCl (33.4 mg) or saline. The infusions were preceded and followed by control periods of 102 min. Cocaine induced a disruption in fetal behavioral state cyclicity and a decrease in the amount of time spent in rapid eye movement sleep (P < 0.01) and non-rapid eye movement sleep (P < 0.05) during the infusion, but not during the recovery period. Spectral amplitude of the electrocortical activity at all three cortical locations increased within most one-third octave bands between 0.8-4 Hz and decreased within most bands between 16-25 Hz (P < 0.05) compared to controls. There were no differences in spectral amplitude between pre- and post-cocaine periods at any location over the 25 frequency bands studied (P > 0.6) except for one frequency band centered at 12.5 Hz. The effects of a one hour cocaine infusion on fetal cortical electrical activity are diffuse, but short-lived, and occur independently of changes in fetal oxygenation.

Animals↗

PubMed1992

Prevalence of out-of-phase endometrial biopsy specimens.

OBJECTIVE: We attempted to determine the prevalence of out-of-phase endometrial biopsy specimens among fertile and infertile women and women with recurrent pregnancy loss, histologic dating of biopsies was compared with four reference points for expected ovulation. These reference points included last menstrual period, next menstrual period, luteinizing hormone testing, and ultrasonographic documentation of ovulation. STUDY DESIGN: Four hundred eighty-five endometrial biopsies were performed 7 days after documented ovulation-based ultrasonographic evidence for follicle collapse. The histologic dating was referenced to the last menstrual period, next menstrual period, and ultrasonographic documentation of ovulation. One hundred thirty-two of these women also performed urinary luteinizing hormone surge testing before ovulation and serum progesterone determinations. A comparison of the prevalence of out-of-phase biopsy specimens among groups was determined with the chi 2 test and Fisher's exact test. RESULTS: The prevalence of out-of-phase endometrial biopsy specimens ranged from 42% when last menstrual period was used to 26% with next menstrual period, to 21% with luteinizing hormone testing, and to 4% with ultrasonographic documentation of ovulation. Serum progesterone values among women with a diagnosis of out-of-phase biopsy specimens by any of the reference dates progesterone were similar to those with in-phase biopsy specimens. CONCLUSION: The accuracy of histologic endometrial dating was best determined by ultrasonographic monitoring rather than by last menstrual period, next menstrual period, or luteinizing hormone testing in infertile populations and in those with recurrent pregnancy loss. Additionally, because no significant difference in out-of-phase biopsy specimens exists between fertile and infertile patients and recurrent pregnancy loss, those with the role of this procedure is called into question.

Abortion, Habitual↗