Biomedical subjects

N Searle

Publications and source records attributed to N Searle.

29 records · Page 2Linked to original sources

PubMed1987

The effects of maternal ambulation on the nonstress test.

Using a recently developed noninvasive telemetry device (model 8240A, Hewlett-Packard Co., Palo Alto, California), we studied, under controlled conditions, the effects of maternal ambulation on the nonstress test patterns of 100 near-term high-risk pregnancies, randomly divided into two equal groups who underwent three alternating 30-minute periods of ambulation and bed rest, beginning either with ambulation (group 1) or bed rest (group 2). Fetal heart rate data were captured and analyzed by a programmed microcomputer for group mean 30-minute fetal heart rate baseline rates and variability and incidences and dimensions of fetal heart rate accelerations and decelerations. Both groups were similar for the maternal and perinatal data examined. The fetal heart rate parameters analyzed were similar within and between each group during each 30-minute testing segment. No episodes of sustained tachycardia or bradycardia were observed. Although 13 fetuses in each group exhibited variable or late decelerations, the incidence of decelerations was no different during periods of rest or ambulation. Maternal ambulation does not elicit abnormal fetal heart rate responses in most high-risk fetuses and may be an acceptable alternative to conventional nonstress test conditions.

Female↗

PubMed1987

Fetal biophysical testing. The effects of prolonged maternal fasting and the oral glucose tolerance test.

Fetal biophysical testing incorporates observations of the fetal heart rate (FHR), fetal breathing movements (FBMs) and fetal trunkal movements (FTMs). These parameters were examined during maternal fasting and glucose loading. Thirty normal term gravidas were studied during a 210-minute session, of which the first 30 minutes served as a fasting control period, following which 20 (group G) received 100 g oral glucose, while 10 (group F) continued fasting. Serum glucose levels in both groups were determined every 30 minutes. FHR, FBMs and FTMs were recorded concurrently using abdominal electrocardiography and real-time ultrasonography and entered on line into a microcomputer. Offline data analysis provided mean 30-minute baseline FHRs, acceleration counts, FBM incidences, FBM rates and FTM incidences. Both groups were similar for gestational age, birth weight and perinatal outcomes. Mean 30-minute FHR baseline was unchanged and similar in both groups. Mean 30-minute FHR acceleration counts and FTM incidences were significantly higher in group F, while FBM incidences and rates were significantly higher in group G. While biophysical testing can be conducted under either set of maternal conditions, different normal standards must be employed, test length must be sufficient to account for normal biologic variations, and biophysical parameters must be monitored concurrently.

Electrocardiography↗

PubMed1987

Clinical significance of fetal tachypnea during antepartum biophysical testing.

Fetal tachypnea has been regarded as a rare finding with a poor perinatal prognosis. Eighteen cases of fetal tachypnea were noted during the biophysical tests of 200 patients. Biophysical testing consisted of concurrent ultrasound observations of fetal breathing and body movements and electronic monitoring of fetal heart rate, coupled with determinations of fetal tone and amniotic fluid volume. Fetal breathing movement frequency and rate, fetal trunkal movement frequency, and baseline fetal heart rate were analyzed on a programmed microcomputer. The mean (+/- SD) breathing rate was 68.2 +/- 6.4 breaths per minute; mean breathing frequency, 55 +/- 22.6%; mean baseline heart rate, 141 +/- 8 beats per minute; mean trunkal movement incidence, 5.5 +/- 2.6%; and mean acceleration frequency, 14.6 +/- 9.8 per hour. No fetus was apneic for more than eight minutes, and there were no significant correlations between fetal breath rates and the other biophysical parameters. There were no perinatal deaths. Seven fetuses experienced perinatal morbidity, of whom five had other abnormalities on biophysical testing. This study indicates that fetal tachypnea occurs more often than previously believed and does not generally signify fetal compromise unless other biophysical abnormalities are also present.

Female↗

PubMed1986

Differential and analytical subfractionation of rat liver components internalizing insulin and prolactin.

Receptor-mediated endocytosis of 125I-insulin and 125I-prolactin into liver parenchymal cells has been studied by quantitative subcellular fractionation. Differential centrifugation yielded three particulate fractions, N (nuclear), ML (large granule), and P (microsomes), and a final supernatant (S). Quantitative differences in the extent and rates of accumulation of 125I-insulin and 125I-prolactin into the fractions were observed. The acidotropic agent chloroquine and the microtubule disrupting agent colchicine were administered separately to rats. The agents increased significantly the T 1/2 of hormone clearance from the liver and augmented the accumulation of both ligands in the low-speed ML fraction. However, differences in the rates of accumulation of insulin and prolactin into all cell fractions were still maintained. Analytical centrifugation of each of the particulate fractions was carried out in order to determine if different endocytic components were specific to insulin or prolactin internalization. This was not the case. An "early" endosomal component of density 1.11 was identified in microsomes. A "late" endosome of density 1.10 was identified in the large granule (ML) fraction. Both endosomal components appeared to accumulate insulin and prolactin but at different rates. Marker enzyme analysis identified the presumed plasma membrane component in microsomes (density approximately 1.155). This component showed a significant difference in the rate of loss of 125I-insulin (T 1/2 approximately 4.1 min) as compared to that of 125I-prolactin (T 1/2 approximately 12.7 min). A further difference in the handling of the ligands was observed in early endosomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Sequential nonstress testing with use of each fetus as its own control.

The sequential nonstress tests of 126 high-risk fetuses were assessed for baseline fetal heart rate, acceleration frequency, amplitude, and duration and the observance of fetal heart rate decelerations. In 108 fetuses (563 tests) with normal perinatal outcomes, no significant trends in these parameters were found. In 18 fetuses (104 tests) with perinatal compromise, 16 had significantly declining acceleration frequencies, 15 had decreasing acceleration duration, four had rising mean baseline rates, and seven, in their last test before delivery, had repetitive late or severe variable decelerations. The last tests of 11 of these 18 fetuses met institutional criteria for reactivity. When the nonstress tests of compromised fetuses were viewed sequentially, acceleration frequency declined by an average of 59% and acceleration duration by an average of 40%. Sequential assessment of the nonstress test, when compared with the use of standard reactivity criteria, improved test sensitivity from 39% to 89% and negative predictive value from 91% to 98%. We conclude that sequential nonstress test assessment in individual fetuses may improve the diagnostic value of this modality and lead to earlier recognition of fetal compromise.

Female↗

PubMed1986

Metastatic pheochromocytoma in pregnancy and fetal biophysical assessment after maternal administration of alpha-adrenergic, beta-adrenergic, and dopamine antagonists.

Metastatic pheochromocytoma, a rare complication of pregnancy, was managed from 30 weeks' gestation until delivery three weeks later with a combination of alpha-adrenergic blockade (Minipres) beta-adrenergic blockade (Timolol), and dopamine synthesis inhibition (Demser). The biophysical parameters of fetal heart rate (FHR) baseline, variability, and reactivity, as well as fetal breathing movements, body movements, tone, and amniotic fluid volume were followed sequentially during this period. A 1450-g growth-retarded infant, who subsequently did well, was delivered by cesarean section; the mother received combined surgical and medical therapy for her metastatic disease in the postpartum period. The initial fetal biophysical alteration observed was a reduction in mean FHR baseline rate; further biophysical test abnormalities appeared only after overt fetal compromise was evident. Sequential multiple parameter biophysical testing in such circumstances appears to be a valid and valuable approach to antepartum management.

Adult↗

PubMed1986

Percent acceleration time: a new method of fetal assessment.

The percent acceleration time (PAT) is a fetal heart rate parameter, which may be derived from the nonstress test (NST). It is based on measurement of the duration of individual movement-associated fetal heart rate accelerations (MAFAs), obtained during a nonstress test, and is calculated by the formula: (formula, see text) The authors studied 148 fetuses undergoing four or more serial nonstress tests who were delivered within one week of their last test. Percent acceleration time of fetuses with normal outcomes had a mean value of 15.5 +/- 10.0 (SD)%, correlated well with the frequency and amplitude of movement-associated fetal heart rate accelerations but was independent of gestational age and mean baseline fetal heart rate. No normal fetus had a percent acceleration time of less than 5% on its last nonstress test, while only one abnormal fetus had a percent acceleration time that exceeded the mean percent acceleration time of the normal group. All abnormal fetuses had a significant progressive decline in percent acceleration time (mean: 50.6%). Percent acceleration time values were more sensitive in identifying fetuses with perinatal compromise than were conventional criteria for nonstress test reactivity, and may provide a useful alternative to assessment of fetal status when other quantitative methods are unavailable (continuous ultrasound visualization) or less reliable (maternal perception, tokodynamometry, palpation).

Female↗

PubMed1985

Computer-assisted assessment of the fetal biophysical profile.

The biophysical profile assesses fetal heart rate, breathing movements, fetal body movements, amniotic fluid volume, and fetal tone. In the past, these data have been scored by an arbitrary, unweighted system. While this approach is useful in detecting major anomalies and oligohydramnios, both static observations, the dynamic variables (fetal heart rate, fetal breathing movements, and fetal body movements) have added little information beyond that of an extended nonstress test alone. We have evaluated an alternative biophysical assessment system, modeled after extended physiologic studies, which not only acquires dynamic fetal variables simultaneously but, with computer assistance, quantifies the biophysical information. With an ADR 4000/L scanner, a Hewlett-Packard 8040 A monitor, and a specially programmed IBM microcomputer, we studied 100 normal term fetuses during 60-minute epochs. Each gestation had normal amniotic fluid volume and fetal tone. Normative values for the dynamic variables, expressed as means +/- SD were: fetal heart rate, 137 +/- 6.3 bpm; incidence of fetal breathing movements, 25.0% +/- 17.3%; rate of fetal breathing movements, 46.0 +/- 9.4 breaths/min; total fetal breathing movements, 823 +/- 61; incidence of fetal body movements, 8.5% +/- 3.9%; accelerations (greater than 15 bpm, 15 seconds), 14.1 +/- 6.3. We conclude that this approach is practicable, respects the biologic cycles of fetal behavior, and provides a basis for population standards and sequential study of the same fetus.

Amniotic Fluid↗

PubMed1985

Nonstress test: dimensions of normal reactivity.

Despite the widespread use of the nonstress test, there has been no consensus on the criteria for normal reactivity. The authors studied 495 nonstress tests of 230 normal term fetuses, using a standardized protocol. The frequency distribution of movement-associated fetal heart rate (FHR) accelerations exceeding 15 beats per minute and 15 seconds' duration was examined in windows, ranging from ten to 40 minutes. Mean, median, and modal frequencies of movement-associated FHR accelerations were determined in 1910, 1418, 895, and 473 windows of ten, 20, 30, and 40 minutes, respectively. No significant difference in movement-associated FHR acceleration frequency was observed for any sequential ten-minute window, but movement-associated FHR accelerations were absent in 19.5, 8.8, 5.2, and 5.0% of 10-, 20-, 30-, and 40-minute windows, respectively. The broad frequency distributions of movement-associated FHR accelerations, produced by normal fetuses, precludes discrete diagnostic cutoffs in short time windows, unless one is willing to accept significant negative predictive errors.

Female↗

PubMed1980

Polypeptide hormone receptors in vivo: demonstration of insulin binding to adrenal gland and gastrointestinal epithelium by quantitative radioautography.

A tissue-screening survey employing quantitative radioautography was carried out at 2 min after the intravascular injection of 125I-insulin into laboratory rats. The results revealed a substantial binding of insulin to cells forming the proximal convoluted tubule in kidney, hepatocytes of liver, acinar cells of the pancreas, parenchymal cells of the adrenal cortex and medulla, and epithelial cells of the gastrointestinal tract. Control experiments indicated that this binding was due to a specific interaction with the insulin receptor, except in the case of kidney where the binding was shown to be nonspecific. Although the major target for insulin action (liver) clearly demonstrated specific insulin binding, several other classical targets (adipocytes, skeletal, cardiac, and smooth muscle cells) showed no specific 125I-insulin binding and therefore indicated the limits of sensitivity of the in vivo radioautographic method. Nevertheless, the working hypothesis of a direct correlation of insulin receptor density with insulin action points to the hitherto unemphasized targets of pancreas, adrenal gland, and gastrointestinal tract as major sites of insulin action in the body.

Adipose Tissue↗

PubMed1980

Radioautographic visualization of in vivo insulin binding to the exocrine pancreas.

Two minutes after the iv injection of [125I]insulin, hormone was linked to specific binding sites distributed randomly along the basal and lateral membranes of plasmalemma of pancreatic exocrine cells. The interaction had all of the properties of bona fide binding to a true insulin receptor, and under the described experimental conditions, estimates of receptor densities indicated the exocrine cell plasmalemma to be one of the richest sources of insulin receptors in the male rat.

Animals↗