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Biomedical subjects

C Randolph

Publications and source records attributed to C Randolph.

17 recordsLinked to original sources
PubMed1992

Visual orienting in schizophrenia.

Patients with schizophrenia demonstrate a variety of attentional impairments which have proven difficult to relate to specific neural systems. Posner et al. (1988) reported an asymmetric slowing of right visual field orienting in schizophrenia similar to that observed in patients with parietal lesions. We examined the visual orienting performance of 19 patients and controls using two different versions of the Posner paradigm. In overall ANOVAs we found main effects of group, cue condition, and delay interval. However, we did not observe any main effect of visual field or interactions involving visual field. There was some evidence of an asymmetric cost of invalid cues similar to those reported by Posner et al. The bulk of data suggests bilateral attentional deficits.

Adult↗
PubMed1992

Forms of memory failure in schizophrenia.

Effortful and automatic memory task performances were examined in 36 schizophrenic patients and 18 normal control Ss. Tasks included free recall, recognition, and frequency estimation. Patients demonstrated impairment in recall, in recognition, in semantic encoding, and in frequency estimation. Deficits were observed across tasks despite differences in attentional demands. The results suggest a basic compromise of memory function, which is consistent with recent neuroimaging evidence of structural or physiological abnormalities in frontal and temporal lobe structures in schizophrenia.

Adult↗
PubMed1992

Release from proactive interference: determinants of performance and neuropsychological correlates.

The Wickens (1970) modification of the Brown-Peterson short-term memory task has been used to investigate release from proactive interference (PI) in a number of memory-impaired groups. It has been suggested that failure to release from PI is observed only in patients with compromise of both memory and 'frontal-lobe' functions. The present study examined performance on this paradigm in patients with schizophrenia (SC), a neuropsychiatric disorder which typically includes both frontal and mnemonic impairments. Patients with SC were found to exhibit significantly less release from PI than normal controls. It was determined through correlational analyses that average Trial 1 performance on this task could predict performance on all subsequent trials, indicating that 'release' from PI may measure the same psychological process as the Brown-Peterson task, which does not include a release condition. Trial 1 performance in the SC group was correlated with a wide range of neuropsychological measures, but after the effect of full scale IQ was partialled out, only correlations with measures of memory and measures of frontal-lobe function remained significant. The results support previous formulations of the neuropsychological concomitants of release from PI, but suggest that failure to release on this paradigm may be secondary to a significant compromise of the ability to perform the Brown-Peterson task. It is proposed that the experimental design constraints necessary to elicit a failure to release from PI in any patient group may limit the utility of this measure, and that Brown-Peterson performance may be a more reliable index of the neuropsychological functions involved.

Adult↗
PubMed1992

Serum concentrations of relaxin, chorionic gonadotropin, estradiol-17 beta, and progesterone during the reproductive cycle of the chimpanzee (Pan troglodytes).

Levels of serum relaxin were measured by a specific RIA and correlated with serum patterns of estradiol-17 beta, progesterone, LH, or cCG during a single menstrual cycle in each of 10 female chimpanzees, and throughout 24 pregnancies in 21 chimpanzees. Significant concentrations of relaxin, higher than those reported for the human being, were detected in serum of nonpregnant chimpanzees during the late luteal phase of the menstrual cycle. During pregnancy in the chimpanzee, serum relaxin concentrations, exceeding levels found during the luteal phase, were highest during the first third of gestation, and declined thereafter. Although the absolute concentrations were higher, the patterns of relaxin secretion throughout the reproductive cycle in chimpanzees was qualitatively very similar to that observed in other primates, including the human being. The chimpanzee should thus provide a useful model for examining the role of relaxin in human reproduction.

Animals↗
PubMed1992

Relationship of birth weight to the phenotypic expression of Gilles de la Tourette's syndrome in monozygotic twins.

We studied 16 pairs of monozygotic twins (mean age, 12.8 +/- 1.4 years; age range, 8 to 26 years; sex, 12 male pairs, four female pairs) in whom at least one twin had Gilles de la Tourette's syndrome (TS) to determine the concordance rates for TS and tic disorders and to examine environmental factors accounting for intrapair differences in tic severity. In this cohort, the concordance rate for TS was 56%, and the concordance rate for tic disorders was 94%, supporting a primary genetic basis for TS and tic disorders with a high rate of penetrance for the gene. Thirteen of the pairs had differing birth weights and the lower birth-weight twin had a higher tic score in 12 of these pairs. The magnitude of the intrapair birth-weight difference (BWD) strongly predicted the magnitude of the intrapair tic score difference. The difference in tic severity could not be explained by any postnatal medical events. These findings suggest that crucial events affecting the phenotypic expression of TS occur in utero and that the factors causing the BWD also are related to tic severity.

Adolescent↗
PubMed1992

Determination of the time of ovulation in chimpanzees by measurement of LH, estrone sulfate, and pregnanediol 3 alpha-glucuronide in urine: comparison with serum hormone patterns.

The concentrations of LH, total estrogens, and pregnanediol 3 alpha-glucuronide (PdG) were determined by specific radioimmunoassays on daily overnight urine samples obtained in 13 menstrual cycles of six adult female chimpanzees during the periods of increasing, maximal, and decreasing tumescence of the perineal sex skin. The peaks of estrogens and LH and the rise in PdG in urine accurately reflected the peaks of estradiol-17 beta and LH and the subsequent rise in progesterone in the serum of the same animals during the same menstrual cycles, and can be used to predict and verify the occurrence of ovulation, thus avoiding the repeated tranquilizations necessary to obtain daily blood samples.

Animals↗
PubMed1991

Implicit, explicit, and semantic memory functions in Alzheimer's disease and Huntington's disease.

A priming task involving a word-stem completion paradigm was administered to patients with Alzheimer's disease (AD), patients with Huntington's disease (HD), and normal control subjects. The task was done under conditions of both implicit and explicit recall. Explicit and implicit recall were positively correlated in all three groups. After controlling for explicit recall ability through ANCOVA, AD patients were found to be normally susceptible to the effects of priming on implicit recall. HD patients, however, exhibited significantly increased susceptibility to priming, suggesting that they may have carried out the implicit task in a manner different from that of normals and AD patients. In a second experiment, AD patients were found to supply words of significantly lower association strength than the other two groups in a "free association" task using words from a published list of word association norms. This apparent degradation of semantic memory was found to be strongly correlated with explicit recall performance, suggesting that explicit, implicit, and semantic memory functions decline in parallel in AD. Results are discussed with respect to the difficulties inherent in attempts to demonstrate selective impairments of conceptually distinct forms of memory.

Aged↗
PubMed1990

CNS side effects of centrally-active antihypertensive agents: a prospective, placebo-controlled study of sleep, mood state, and cognitive and sexual function in hypertensive males.

A prospective, placebo-controlled, comparative evaluation was conducted on two widely prescribed, sympatholytic antihypertensive agents with known CNS effects. In order to separately assess these effects in younger and older male hypertensives, patients were assigned to either of two treatment studies based on age. For study I, 24 males aged 31-59 (mean = 49.8; SD = 7.4) with mild hypertension (mean DBP = 100.2 mm Hg; SD = 8.0) received 3 months of treatment with propranolol (20-80 mg bid), clonidine (0.1-0.3 mg bid), or double-blind placebo in a counterbalanced, crossover design. For study II, 23 elderly hypertensive males (mean DBP = 102.6 mm Hg; SD = 8.2) aged 60-78 years (mean = 65.1; SD = 4.6) were randomized to propranolol (20-40 mg bid) or double-blind placebo therapy. Patients received cognitive testing, mood assessments, and all-night polysomnographic evaluations before and after each treatment period. Multivariate analysis of EEG sleep data was statistically significant for study I, with significant univariate effects on four of the six primary sleep variables: total sleep time was reduced, sleep maintenance decreased, REM latency increased, and percent total REM time was reduced. A similar MANOVA analysis for the effects of treatment on the sleep of older patients (study II) was not significant. However, propranolol administration was found to be associated with a significant decline in cognitive performance in these patients. Significant mood effects were observed with each of the study drugs, and nocturnal penile tumescence (NPT) was significantly decreased in both younger and older patients. Overall, this research suggests that distinct patterns of CNS effects are associated with each of the antihypertensive agents studied.

Adult↗
PubMed1990

Species-specific oligodeoxynucleotide probes for the identification of periodontal bacteria.

Oligodeoxynucleotide probes were developed for identification of the periodontal bacteria Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, B. intermedius types I and II, B. forsythus, Eikenella corrodens, Fusobacterium nucleatum, Haemophilus aphrophilus, Streptococcus intermedius, and Wolinella recta. Probes were designed by sequencing the 16S rRNA for each bacterium, identifying hypervariable regions, and chemically synthesizing species-specific probes. These probes were specific when tested against a panel of nucleic acids from closely related bacteria.

Bacteria↗
PubMed1989

Physiological response patterns to cognitive testing in adults with closed head injuries.

Physiological measures were taken from 7 closed-head-injured patients and 7 control subjects while they took a series of cognitive tests: the finger tapping test from the Halstead Reitan battery, the Digit Symbol test from the WAIS-R, a test of logical memory, and a paced arithmetic test. Physiological reactivity was assessed relative to rest periods, which occurred at the beginning and end of each session. The tests and physiological assessment were administered twice, approximately one month apart. The patient group performed more poorly on the cognitive tests, and showed less physiological reactivity during them than did the control group. This pattern was statistically significant for heart rate, frequency of electrodermal responses, and, during the initial session, respiration rate. The control group also showed greater finger pulse amplitude during the first posttest rest period in the first session, and greater constriction during a logical memory task in the second session. No significant between-groups differences emerged for state or trait anxiety. The patients showed higher frontalis EMG and respiration rate during rest. These results suggest a pattern of poor physiological modulation for task performance in the patients with closed head injuries. The therapeutic implications are discussed.

Adolescent↗
PubMed1989

Encephalopathy as a presentation of pediatric AIDS: case report.

Fifty to ninety percent of pediatric AIDS cases are complicated by neurologic dysfunction. We present a case of a 5-year-old black female with AIDS encephalopathy and Mycobacterium avium intracellulare. Her initial presentation was that of neuroencephalopathy with loss of developmental milestones, pyramidal tract signs, and subsequent evidence of cortical atrophy. Her initial CT scan at the time of frank encephalopathy was normal, whereas 18 months into the clinical course of her encephalopathy, her CT scan of the head demonstrated typical ventricular dilatation and severe cortical atrophy consonant with her clinical picture. She subsequently developed Mycobacterium avium intracellulare documented by gastric aspirate culture and other opportunistic infections including Candida esophagitis. Her neuroencephalopathy plateaued with continued evidence of immune dysfunction and mycobacterium by gastric aspirate, despite triple antibiotic therapy with INH, streptomycin, Pyrazinamide with later addition of Rifampin and final substitution of the investigational congener Rifabutin. AIDS encephalopathy and Mycobacterium intracellulare are discussed in terms of their prognosis and therapy, particularly in view of new reports of the application of AZT and immunoglobulin therapy.

AIDS Dementia Complex↗
PubMed1988

EEG and cognitive performance following closed head injury.

Ten closed head-injured patients and 10 matched control subjects participated in a study that examined quantitated EEG data during cognitive task performance. The head-injured patients performed significantly worse than controls on all four tasks and had significantly higher EEG amplitudes and amplitude variances. A discriminant analysis function correctly identified 0% of the subjects on the basis of the EEG data. Frequency analysis indicated that these higher amplitudes were a product of across-frequency increases in voltage. In addition, EEG data were significantly correlated with performance on one cognitive task in the head-injured group. Results suggest that, contrary to standard clinical EEG findings, identifiable EEG changes may persist for years following moderate to severe closed head injury, and these changes are related to residual cognitive deficits.

Adolescent↗
PubMedDate not supplied

Duration of response following cessation of pollen immunotherapy.

Following successful immunotherapy estimates of relapse rate ranged from 22% to 42%, depending on method of follow-up. The time to relapse varied with the method of follow-up, indicating that recall may play a major role in the perception of a relapse. How much of the continued well-being of most patients (58% of contacted patients) is due to immunotherapy or the natural history of the illness cannot be ascertained from this study.

Humans↗