Biomedical subjects

R A Stern

Publications and source records attributed to R A Stern.

53 records · Page 3Linked to original sources

PubMed1991

Recurrent mild abruptio placentae occurring immediately after repeated electroconvulsive therapy in pregnancy.

We present a case in which electroconvulsive therapy was performed repeatedly in pregnancy because of severe depression with psychotic features and failure of chemical treatment. Each electroconvulsive treatment was immediately followed by uterine contractions and active uterine bleeding, possibly representing recurrent abruptio placentae occurring in association with the treatment. Transient acute episodes of maternal hypertension between 180/90 and 190/100 mm Hg, documented within minutes after application of each electroconvulsive treatment, might explain the abruptio placentae manifested by active uterine bleeding and uterine hyperstimulation.

Abruptio Placentae↗

PubMed1991

Histopathology of monopolar transcatheter radiofrequency ablation at the mitral valve annulus.

Although monopolar radiofrequency (RF) catheter ablation is being used to interrupt left-sided accessory pathways in patients with tachyarrhythmia, little is known of the histologic effects from this method of treatment. RF ablation at the mitral valve (MV) annulus was performed in ten dogs to examine the histology of the lesion area. A custom 6 French ablation catheter with a 4 mm distal electrode was positioned beneath the MV adjacent to the annulus. Mean preablation atrial to ventricular electrogram ratio (A/V ratio) was 0.26 +/- 0.17. Thirty +/- 1 watts of RF power were applied for 53 +/- 13 seconds between the distal electrode and a large skin electrode. Nine dogs were sacrificed 6 weeks and one dog 2 days following ablation. Annular lesions were seen in eight of the ten dogs. Lesion volume was 136 +/- 41 mm3 and correlated with the A/V ratio (r2 = 0.74, P = 0.006). Lesions consisted of necrosis of the left ventricle with extension into the atrioventricular groove and left atrium. No injury to the coronary sinus or circumflex artery was observed. A small area of injury was noticed on the mitral leaflet in one dog. Monopolar RF ablation creates lesions at the MV annulus without injury to adjacent vascular structures.

Animals↗

PubMed1991

Depressive symptoms following stroke.

OBJECTIVE: The primary purpose of this study was to assess the relation of lesion location to mood and vegetative disturbance following stroke. METHOD: Fifty-two inpatients and outpatients who had had single, unilateral strokes were included. Patients with past CNS or psychiatric disorders were excluded. A modified Visual Analogue Dysphoria Scale was used to allow the inclusion of all but the most impaired aphasic patients. Sleep and eating disturbances were measured by using both self-report and nursing assessments. Location of lesions was determined by CT scan and classified according to three dimensions: right-left, dorsal-ventral, and frontal-nonfrontal. RESULTS: On measures of dysphoric mood and sleep disturbance, results indicated significant three-way interactions among the three lesion dimensions. No differences were found with regard to eating disturbance. Greater dysphoria and sleep disturbance were found in subjects with left parietal/occipital, left inferior frontal, right superior frontal, and right temporal lesions than in subjects with lesions in other locations. Depressive symptoms were not associated with functional impairment as measured by activities of daily living, motor strength, or severity of aphasia. CONCLUSIONS: These results support the hypothesis that lesion location is a valid and significant factor in the mixture of influences which may result in a dysphoric mood state following stroke. The relation between the site of the lesion and subsequent depressive symptoms, however, may be more complex than has been reported previously.

Activities of Daily Living↗

PubMed1990

Antibodies to the beta-amyloid peptide cross-react with conformational epitopes in human fibrinogen subunits from peripheral blood.

Antibodies to the Alzheimer disease (AD) beta-amyloid peptide (beta AP) were used to identify beta AP precursor fragments in blood. The antibodies detected 3 major polypeptides with apparent molecular weights (MW) of 47-64,000 in Western blots of plasma derived clot proteins, but these proteins corresponded to human A-alpha, B-beta and gamma-fibrinogen since they reacted with 2 different anti-fibrinogen antisera, and the anti-beta AP and anti-fibrinogen antibodies recognized purified fibrinogen and fibrin. These data are significant for efforts to develop immunochemical assays to diagnose and monitor the progression of AD.

Adrenal Gland Neoplasms↗

PubMed1990

Stages of adolescent tobacco-use acquisition.

The present study extended the results of previous research in applying the "stages of acquisition" model to the onset of smokeless tobacco as well as cigarette use. Three expert judges classified an initial pool of items as to whether they represented "precontemplation," "contemplation," "action," or "maintenance" stages of smokeless tobacco acquisition. Fifty items with adequate inter-rater reliability were combined with 21 previously developed items pertaining to cigarette smoking acquisition in an overall tobacco acquisition questionnaire, which in turn was administered to 358 junior and senior high public school students. Three distinct components labeled precontemplation, action, and maintenance were delineated through principal component analyses. Coefficient alphas and discriminant analyses according to self-reported use demonstrated adequate reliability and validity for the new smokeless tobacco- and previously developed smoking-acquisition scale.

Adolescent↗

PubMed1989

Instantaneous and continuous cardiac output obtained with a Doppler pulmonary artery catheter.

A newly developed, flow-directed, Doppler pulmonary artery catheter, capable of measuring instantaneous and continuous cardiac output, was evaluated in both an in vitro pump model and an animal model. Quantitative flow was calculated with use of the instantaneous, space-average velocity (obtained from the velocity profile) and the instantaneous area (obtained from the vessel diameter) and compared with electromagnetic flow. Additionally, simultaneous thermodilution flow measurements were obtained. Doppler catheter-determined flow was highly predictive of electromagnetic flow in both continuous and pulsatile pump models (r2 = 0.98, slope or m = 1.04, SEE = 0.44; and r2 = 0.97, m = 1.04 and SEE = 0.33, respectively). Thermodilution was less predictive and appeared to underestimate electromagnetic flow in both the continuous and the pulsatile model (r2 = 0.99, m = 0.91, SEE = 0.20 and r2 = 0.95, m = 0.84 and SEE = 0.34, respectively). In the animal model, Doppler catheter-determined cardiac output appeared to modestly underestimate electromagnetic flow (r2 = 0.80, m = 0.87, SEE = 0.61). However, Doppler determinations of flow remained more accurate than did simultaneous thermodilution measurements (r2 = 0.73, m = 0.79, SEE = 0.72). Accurate, continuous and instantaneous cardiac output measurements appear possible with use of a flow-directed, Doppler pulmonary artery catheter. This catheter system also provides instantaneous diameter measurements and mapping of instantaneous velocity profiles within the main pulmonary artery and may lead to more accurate Doppler-derived assessment of cardiac output in humans.

Animals↗

PubMed1989

Monoclonal antibodies to a synthetic peptide homologous with the first 28 amino acids of Alzheimer's disease beta-protein recognize amyloid and diverse glial and neuronal cell types in the central nervous system.

Studies were conducted to identify neural cells that synthesize and/or process cerebral amyloid using antisera and monoclonal antibodies (MAbs) raised to synthetic peptides based on the first 28 amino acids of the amyloid beta-protein. Using rabbit and mouse antisera, and 7 MAbs, sections of neocortex, hippocampus, cerebellum, and spinal cord from Alzheimer's disease (AD), Down's syndrome (DS), and control cases were probed. The antibodies produced 3 distinct immunohistochemical patterns: 1) staining restricted to neuritic plaque and blood vessel amyloid only (antisera, 1 of 7 MAbs); 2) immunoreactivity confined to cytoplasmic granules in diverse neuronal, glial (astrocytes, ependyma) and other (leptomeningeal, perivascular, choroid plexus) cells (1 of 7 MAbs); 3) a summation of these 2 patterns (5 of 7 MAbs). Controls resembled the AD and DS cases, except for a paucity of immunoreactive plaques and blood vessels in the controls. Immunoreactivity was reduced or removed by the peptides used to produce these antibodies. Formalin- and Bouins-fixed tissues reacted weakly or not at all with these antibodies while microwave denatured tissues reacted very intensely with them. Specific staining was enhanced by treatment of the tissue sections with Triton X-100, NaDodSO4, or trypsin. These studies significantly extend earlier studies that localized amyloid beta-protein precursor mRNA to human brain cells, and they suggest that the beta-protein, its precursor, and/or fragments thereof may exist in diverse neural cell types in AD, DS, and control brains.

Alzheimer Disease↗

PubMed1989

Elevated intraocular pressure following penetrating keratoplasty.

IOP was retrospectively studied in 229 consecutive cases of PK, with a mean follow-up period of 84 weeks. Twenty-seven percent of the cases had preoperative glaucoma, three-fourths of which were medically controlled prior to keratoplasty. Following PK, 34% of the total sample developed sustained elevated IOP but only five (2%) patients required surgical treatment for glaucoma. The mean time from PK to first IOP rise was 24 weeks. Variables which were significantly associated with IOP rise included preoperative glaucoma (P less than .001), aphakia (P less than .01), and IOL removal (P less than .01). When eyes with preoperative diagnoses of glaucoma were excluded from the analysis, aphakia was no longer associated with postoperative IOP rise. Keratoconus patients were at significantly less risk than patients with other corneal diagnoses. Factors not associated with IOP rise included previous PKs, pseudophakia, intraoperative vitrectomy, PAS lysis, iridoplasty, secondary IOL placement, and concomitant cataract extraction with IOL (triple procedure).

Aphakia↗

PubMed1987

Stages of adolescent cigarette smoking acquisition: measurement and sample profiles.

A stage model of adolescent cigarette smoking acquisition was developed and an instrument to measure the stages was created. Internal validity was obtained based on principal component analysis, item analysis, and coefficient alpha. Three distinct components were labeled precontemplation, decision-making, and maintenance. The scales had reliability coefficients ranging from .86 to .94. External validity was obtained by relating the scale scores to measures of smoking behavior and intent to smoke. A cluster analysis resulted in nine distinct clusters, including profiles representing precontemplation, contemplation, decision-making, action, and maintenance stages. Further validity was obtained for the clusters by comparing groups on the perceived positive and negative consequences of smoking, and the derived pleasure from smoking.

Adolescent↗

PubMed1986

The ABCs of adolescent smoking prevention: an environment and skills model.

Smoking prevention programs vary dramatically in terms of the primary focus of the interventions. Most current programs are based on a Social Pressures Model of smoking acquisition which focuses on antecedents and specific behavioral aspects of smoking. Based on social skills and operant behavioral perspectives, an Environment and Skills Model of smoking acquisition and prevention is proposed. This model involves an integrated examination of the antecedents, behaviors, and consequences of smoking. The importance of the "consequence end" of this three-term contingency is discussed as is the differential effectiveness of prevention strategies and suggestions for future research.

Adolescent↗

PubMed1985

Scatterer-induced frequency variations in reflected acoustic pulses: implications for tissue characterization.

A Hilbert transform approach to the detection of the instantaneous center frequency of reflected ultrasonic pulses was performed for simulated reflected ultrasonic pulses, and digitized ultrasonic waveforms from tissue phantoms. Considerable center frequency modulation was observed for both simulated and recorded ultrasonic waveforms. This phenomenon of frequency modulation can be explained with the aid of a phasor model, in which variations in instantaneous frequency results from the interaction of a multitude of overlapping ultrasonic pulses arising from different scattering centers in tissue. The observed frequency modulation of ultrasonic signals has important implications for tissue characterization techniques, including the measurement of attenuation by the determination of the shift in ultrasonic center frequency.

Mathematics↗

PubMed1984

Measurement of attenuation and scatterer spacing in human liver tissue: preliminary results.

A study measuring two quantitative parameters of human liver in vivo was performed to assess the reliability of measurement of the two parameters, and to evaluate their potential for diagnosing and grading diffuse fibrotic liver disease. The parameters measured were attenuation and "mean scatterer spacing," a measure of tissue structure. Components of variance analysis demonstrated that variation in the measured parameters was a function of the subject being examined, with significant variation noted between data acquisition sessions performed the same day. There was no significant additional variation of the measurements from week to week over a one-month period. A good correlation of the parameters with the severity of liver disease indicates that the technique may be useful in the clinical evaluation of diffuse liver disease.

Analysis of Variance↗

PubMedDate not supplied

Thyroid and adrenal measures during late pregnancy and the puerperium in women who have been major depressed or who become dysphoric postpartum.

Prior studies of thyroid, adrenal and mood measures during pregnancy and the puerperium, which we review, have not examined hormone-mood relationships over the full peripartum period during which hormone levels change nor have they compared prior depression history with hormone changes. In a pilot study we measured thyroid and adrenal hormones as well as mood at 38 weeks of pregnancy, and 1, 3, 6, 9 and 12 weeks postpartum in 12 women with major depression history and 14 women with negative psychiatric history. Subjects with prior depressions had significantly higher T3, T4, TSH and cortisol levels during the puerperium. Subjects with higher levels of postpartum dysphoria had lower T4 and free T4 levels as well as higher T3 uptake at 38 weeks of pregnancy and higher cortisol levels during the puerperium. The pathophysiological implications of these findings are discussed.

Adult↗

PubMedDate not supplied

A guide for applying principal-components analysis and confirmatory factor analysis to quantitative electroencephalogram data.

Principal-components analysis (PCA) has been used in quantitative electroencephalogram (qEEG) research to statistically reduce the dimensionality of the original qEEG measures to a smaller set of theoretically meaningful component variables. However, PCAs involving qEEG have frequently been performed with small sample sizes, producing solutions that are highly unstable. Moreover, solutions have not been independently confirmed using an independent sample and the more rigorous confirmatory factor analysis (CFA) procedure. This paper was intended to illustrate, by way of example, the process of applying PCA and CFA to qEEG data. Explicit decision rules pertaining to the application of PCA and CFA to qEEG are discussed. In the first of two experiments, PCAs were performed on qEEG measures collected from 102 healthy individuals as they performed an auditory continuous performance task. Component solutions were then validated in an independent sample of 106 healthy individuals using the CFA procedure. The results of this experiment confirmed the validity of an oblique, seven component solution. Measures of internal consistency and test-retest reliability for the seven component solution were high. These results support the use of qEEG data as a stable and valid measure of neurophysiological functioning. As measures of these neurophysiological processes are easily derived, they may prove useful in discriminating between and among clinical (neurological) and control populations. Future research directions are highlighted.

Adolescent↗

PubMedDate not supplied

A biologically compatible implantable ultrasonic marker.

An implantable passive ultrasonic marker has been developed which can be detected with a conventional pulse echo imaging system. The marker consists of a planar array of 1/16 in. diameter stainless steel (316L) spheres and produces a distinct and characteristic reflection signature due to reverbation within the spheres. The marker has undergone both in vitro and in vivo tests and is biologically compatible for chronic implantation. It is consistently detectable at depths up to 10 cm from the transducer. An application to the detection of flow conditions in aortocoronary bypass grafts is suggested.

Animals↗

PubMedDate not supplied

Psychological aspects of premenstrual syndrome. I: Cognition and memory.

Fourteen women with PMS and ten without PMS were evaluated with a battery of neuropsychological tests during the follicular and late luteal phases of two consecutive menstrual cycles. Classification was determined with NIMH diagnostic criteria and prospective record keeping. The results indicated that (1) the PMS women had significant difficulty in learning new material and this problem was not phase-dependent, (2) both groups performed better on a test of frontal lobe function during the follicular phase, and (3) mood did not account for any of the differences in cognitive functioning.

Adult↗

PubMedDate not supplied

Envelope amplitude analysis following narrow-band filtering: a technique for ultrasonic tissue characterization.

Ultrasonic waveforms backscattered from tissue simulating phantoms and from normal and cirrhotic human livers in vivo were digitized to a standard dynamic range prior to envelope detection and determination of envelope amplitude distributions. For 11 individual narrow-band Gaussian-shaped filters of -6 dB bandwidth 200 kHz, and of center frequencies from 2 to 4 MHz, envelope amplitude distributions were plotted and mean values of the values distributions computed. Analysis of data was performed for data from a phantom containing only relatively small graphite scatters (less than 170 mu), and a similar phantom to which glass spheres 0.5 mm in diameter had been added homogeneously. For lower center frequency narrow-band filters, significantly more high-amplitude occurrences were observed for data from the phantom to which glass spheres had been added. Higher center frequency narrow-band filters gave significantly more high-amplitude occurrences for the phantom containing only small scatters. Similar data analysis was performed for in vivo human liver data from ten normal subjects and five patients with known cirrhosis of the liver. For the cirrhotic and normal livers, data analysis using narrow-band filters of relatively low center frequency resulted in more high- amplitude occurrences for cirrhotic, compared to normal liver; the converse was true for narrow-band filtration at relatively high center frequencies. Determination of mean amplitude following narrow-band filtration with a filter centered at 3.4 MHz was found to be quite repeatable for the normal and cirrhotic liver data; analysis of variance showed the measurement was 94.1% a function of the subject examined, and 5.9% related to the data acquisition session.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗