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S M Resnick

Publications and source records attributed to S M Resnick.

At least 55 records · Page 3Linked to original sources
PubMed1994

Lateralized increases in cerebral blood flow during performance of verbal and spatial tasks: relationship with performance level.

Physiologic neuroimaging studies have shown lateralized regional increase in brain activity during cognitive tasks, but the hypothesis that such changes are correlated with task performance has not been tested directly. We examined cerebral blood flow (CBF) changes induced by cognitive tasks in relation to performance. CBF was measured with the 133Xenon clearance method in 34 normal right-handed young (age < 30) volunteers during resting baseline and during the performance of a verbal analogies and a spatial line orientation test. Performance measures included "speed" and "power" estimates of both activation tasks. Resting CBF was moderately correlated with performance. The correlations were slightly higher with activated CBF for verbal but not spatial performance. The degree of increase (task-baseline) did not correlate with performance for either task. The highest and topographically specific correlations were obtained between laterality of CBF and verbal performance. Higher left hemispheric activation was correlated with verbal performance, and this correlation was significantly higher in the angular gyrus region. For the spatial task the correlations were with relatively higher right hemispheric activation but without regional specificity. The results underscore the importance of integrating behavioral performance data with physiologic measures in neuroimaging activation studies.

Adolescent↗
PubMed1994

Physiological properties and substrate specificity of a pentachlorophenol-degrading Pseudomonas species.

A bacterial strain capable of utilizing pentachlorophenol (PCP) as sole source of carbon and energy for growth was isolated from enrichment cultures containing 100 mg/l PCP in a mineral salts medium inoculated with contaminated soil from a lumber treatment waste site. The isolate, designated strain SR3, was identified as a species of Pseudomonas by virtue of its physiological and biochemical characteristics. Mineralization of PCP by Pseudomonas sp. strain SR3 was demonstrated by loss of detectable PCP from growth medium, stoichiometry of chloride release (5 equivalents of chloride per mole of PCP), and formation of biomass consistent with the concentration of PCP mineralized. PCP-induced cells of strain SR3 showed elevated rates of oxygen consumption in the presence of PCP, and with different chlorinated phenols, with complete degradation of 2,3,5,6-, 2,3,6-, 2,4,6-, 2,4-, and 2,6-chloro-substituted phenols. Concentrations of PCP up to 175 mg/liter supported growth of this organism, but maximal rates of PCP removal were observed at a PCP concentration of 100 mg/liter. Based on its degradative properties, Pseudomonas sp. strain SR3 appears to have utility in bioremediation of soil and water contaminated with PCP.

Biodegradation, Environmental↗
PubMed1994

The stability of tachistoscopic measures of hemispheric specialization.

Two-week test-retest reliabilities were determined for two tachistoscopic tasks, consonant-vowel-consonant trigrams and dot location, in 48 right-handed university students. Both visual field and laterality scores were examined. Analysis of variance showed no significant main effects or interactions of session for either task, indicating stability of mean performance and laterality scores. Likewise, grouping subjects as "high" or "low" by median laterality scores showed concordance across sessions for both tasks. Test-retest correlations were moderately high for all verbal task measures and for visual field scores for the dot location test. However, laterality indices for dot location showed low stability despite comparable within-session reliabilities of laterality scores for the two tasks. These findings suggest stability of group means and subgroups for verbal and dot location tachistoscopic measures. However, the degree to which individual scores are predictable from one session to the next differs between the two tasks.

Adult↗
PubMed1994

Magnetic resonance imaging in schizophrenia: relationship with clinical measures.

Relationships were examined between clinical features of schizophrenia and cerebrospinal fluid (CSF) volume in brain obtained by magnetic resonance imaging (MRI) in a sample of 59 patients. The volumes of the cerebral hemispheres and CSF were measured with a computer program designed to separate reliably neural tissue from CSF. The CSF to cranial volume ratios were related to history, symptom profile and outcome functioning. Earlier age of onset was associated with higher sulcal CSF ratio, r = -0.40. The anatomic measures were unrelated to symptom severity. However, patient subtypes differed in the laterality of measures. Higher left hemispheric ratios were seen in patients with severe negative symptoms, and left predominance of ventricular relative to sulcal ratios was associated with the presence of hallucinations and delusions. The results suggest that while higher CSF is related to earlier age of onset, the clinical symptoms are more related to its lateralization. This is consistent with the hypothesis that schizophrenia is a lateralized brain disease.

Adolescent↗
PubMed1994

Regiospecific and stereoselective hydroxylation of 1-indanone and 2-indanone by naphthalene dioxygenase and toluene dioxygenase.

The biotransformation of 1-indanone and 2-indanone to hydroxyindanones was examined with bacterial strains expressing naphthalene dioxygenase (NDO) and toluene dioxygenase (TDO) as well as with purified enzyme components. Pseudomonas sp. strain 9816/11 cells, expressing NDO, oxidized 1-indanone to a mixture of 3-hydroxy-1-indanone (91%) and 2-hydroxy-1-indanone (9%). The (R)-3-hydroxy-1-indanone was formed in 62% enantiomeric excess (ee) (R:S, 81:19), while the 2-hydroxy-1-indanone was racemic. The same cells also formed 2-hydroxy-1-indanone from 2-indanone. Purified NDO components oxidized 1-indanone and 2-indanone to the same products produced by strain 9816/11. P. putida F39/D cells, expressing TDO, oxidized 2-indanone to (S)-2-hydroxy-1-indanone of 76% ee (R:S, 12:88) but did not oxidize 1-indanone efficiently. Purified TDO components also oxidized 2-indanone to (S)-2-hydroxy-1-indanone of 90% ee (R:S, 5:95) and failed to oxidize 1-indanone. Oxidation of 1- and 2-indanone in the presence of [18O]oxygen indicated that the hydroxyindanones were formed by the incorporation of a single atom of molecular oxygen (monooxygenation) rather than by the dioxygenation of enol tautomers of the ketone substrates. As alternatives to chemical synthesis, these biotransformations represent direct routes to 3-hydroxy-1-indanone and 2-hydroxy-1-indanone as the major products from 1-indanone and 2-indanone, respectively.

Biotransformation↗
PubMed1993

Oxidation of carbazole to 3-hydroxycarbazole by naphthalene 1,2-dioxygenase and biphenyl 2,3-dioxygenase.

Naphthalene 1,2-dioxygenase from Pseudomonas sp. NCIB 9816-4 and biphenyl dioxygenase from Beijerinckia sp. B8/36 oxidized the aromatic N-heterocycle carbazole to 3-hydroxycarbazole. Toluene dioxygenase from Pseudomonas putida F39/D did not oxidize carbazole. Transformations were carried out by mutant strains which oxidize naphthalene and biphenyl to cis-dihydrodiols, and with a recombinant E. coli strain expressing the structural genes of naphthalene 1,2-dioxgenase from Pseudomonas sp. NCIB 9816-4. 3-Hydroxycarbazole is presumed to result from the dehydration of an unstable cis-dihydrodiol.

Bacteria↗
PubMed1993

Sex differences in mental rotations: an effect of time limits?

It has been argued that the male performance advantage on the Mental Rotations Test, a measure of three-dimensional rotational ability, reflects a slower problem-solving strategy in females. A recent study of a high-ability sample suggested that sex differences do not reach significance when the test is administered without time limits (Goldstein, Haldane, & Mitchell, 1990). To further explore the effects of time limits, unspeeded versions of the Mental Rotations Test and a vocabulary test were administered to 88 males and 94 females, who represented a less restricted range of ability levels. Males obtained significantly higher scores than females on the Mental Rotations Test (p = .0001), despite comparable performance for the two groups on the vocabulary test. In addition, distributions of Mental Rotations scores were significantly different, with greater proportions of men at the high and women at the low ends. Thus, a difference in speed of problem solving strategy is not a sufficient explanation of the sex difference on the Mental Rotations Test.

Adolescent↗
PubMed1993

Sensation seeking in opposite-sex twins: an effect of prenatal hormones?

Intrauterine hormones and position with respect to male and female littermates influence sexually dimorphic adult behavior in litter-bearing animals. Opposite-sex dizygotic twins offer the opportunity to examine analogous effects on sex-related human behaviors. To illustrate this approach, Sensation Seeking Scale (SSS) scores from 422 British twin pairs, including 51 opposite-sex pairs (Zuckerman, M., et al., J. Consult. Clin. Psychol. 46:139-149, 1978), were reanalyzed. Zuckerman et al. (1978) have shown that some aspects of sensation seeking are consistently increased in males relative to females. In comparing age-adjusted data for opposite and same-sex twins, our reanalysis demonstrated the predicted increase in sensation seeking in female members of opposite-sex pairs. Results were significant for measures of disinhibition, experience seeking, and overall sensation seeking. In contrast, male opposite-sex twins were not significantly different from male same-sex twins. Although psychosocial explanations of the increased sensation seeking in opposite-sex female twins cannot be excluded, these finding are consistent with hypothesized in utero hormonal influences on later behavioral development.

Adolescent↗
PubMed1993

Toxicological assessment of biodegraded pentachlorophenol: Microtox and fish embryos.

A Gram-negative bacterium, Pseudomonas sp. strain SR3, was isolated from soil at a former wood treatment plant in north central Florida. The ability of this bacterium to degrade pentachlorophenol (PCP) was confirmed by growing cells in a basal salts medium in which PCP was the only source of carbon and energy. Degradation from a measured concentration of 39-40 micrograms PCP/ml to 0.0006 micrograms PCP/ml was observed within 120 h of incubation in the presence of PCP-induced cells of Pseudomonas sp. strain SR3. The initial cell density in these cultures was 6 x 10(6) cfu/ml. Microtox 5 min EC50 toxicity tests revealed that aqueous solutions of PCP, measured concentrations 39-40 micrograms/ml were toxic but that final biodegraded samples, 0.0006 micrograms PCP/ml were nontoxic. However, bioassays with embryonic inland silversides, Menidia beryllina, showed that the biodegraded samples were embryotoxic or teratogenic. Water containing added PCP at concentrations up to 30 times higher than measured in the final biodegraded samples was less toxic/teratogenic. These results indicate that while biodegradation of PCP was nearly complete, intermediate metabolites of the degradation process or undegraded impurities in PCP were toxic or teratogenic. Thus, the M. beryllina bioassay allows extremely sensitive assessment of toxicity associated with biodegraded environmental pollutants and may be a useful criterion for determining whether bioremediated water or soil is safe for discharge back into the environment.

Abnormalities, Drug-Induced↗
PubMed1993

A family history study of rapid-cycling bipolar disorder.

Previous studies have yielded mixed evidence as to whether rapid-cycling bipolar disorder (four or more episodes per year) is associated with a distinctive pattern of patient characteristics and familial aggregation of affective disorder. In this study, Family History Research Diagnostic Criteria (FH-RDC) were used to interview 165 patients with rapid-cycling bipolar disorder, non-rapid-cycling bipolar disorder, or recurrent unipolar depressive disorder about the psychiatric history of 812 adult first-degree relatives. In a validity study, FH-RDC diagnoses were demonstrated to agree reasonably well with best-estimate diagnoses by two psychiatrists/psychologists, based on direct interviews with the Structured Clinical Interview for DSM-III-R. Relatives of patients with recurrent unipolar depression were less likely to have bipolar disorder and more likely to have unipolar depression than were relatives of rapid-cycling or non-rapid-cycling bipolar patients. Rapid-cycling patients were younger and more likely to be female than non-rapid-cycling patients. The relatives of rapid cyclers did not differ significantly from those of non-rapid cyclers in the prevalence of bipolar disorder, unipolar disorder, rapid-cycling bipolar disorder, or substance abuse. However, there were nonsignificant trends for the relatives of rapid-cycling bipolar patients, compared with those of non-rapid-cycling bipolar patients, to have more substance abuse and less bipolar disorder given the presence of affective disorder.

Adult↗
PubMed1993

Effects of memory processing on regional brain activation: cerebral blood flow in normal subjects.

The role of the temporal lobe in memory has been implicated in lesion studies, which have also suggested the hypothesis of greater left hemispheric involvement in verbal, and right hemispheric involvement in facial memory. We tested these hypotheses in a sample of 27 normal right-handed subjects using the 133Xenon clearance method for measuring cerebral blood flow (CBF). The CBF was measured during resting baseline, word recognition, and face recognition conditions in counterbalanced order. CBF increased during recognition compared to baseline, and for the midtemporal lobe this increase was asymmetric to the left hemisphere for words and to the right for faces. While overall CBF levels and task related increases in CBF were uncorrelated either with performance or with delta performance (excess performance relative to basal memory abilities), laterality of task-related CBF correlated with both performance indices, showing regional specificity of correlations. This neurobehavioral probe paradigm can be applied in the study of neural substrates of normal and disturbed memory.

Adult↗
PubMed1993

Comparison of anatomically-defined versus physiologically-based regional localization: effects on PET-FDG quantitation.

The potential of anatomic imaging to improve the quantitative accuracy of functional brain imaging through refined regional definition is widely accepted. However, there are little data addressing the impact of approach to regional localization on quantitation of metabolic images in the absence of gross structural pathology. We compared MRI-based versus PET-based approaches to the analysis of PET 18F-fluorodeoxyglucose (FDG) images using a standard adjustable template based on simple geometric regions. For the MRI-based approach, templates and individual regions were adjusted to each individual's anatomy, whereas the PET-based definition involved only global proportional adjustment of the standard templates. Metabolic rates for glucose and volume-to-whole brain ratios were determined by two operators for 78 volumes of interest in five subjects. Pairwise correlations indicated high interoperator agreement for each approach and high intraoperator agreement for MRI-based versus PET-based metabolic values. The stability of the metabolic rates and ratios among operators and analysis approaches was supported by low coefficients of variation across measurements and small average differences in paired comparisons. Thus, within the current spatial resolution of PET imaging, quantitation of metabolic images is relatively robust to image analysis approach in the absence of gross structural abnormality. To take advantage of the greater quantitative accuracy promised by high-resolution anatomic and functional imaging, more refined delineation of anatomic images will be necessary.

Brain↗
PubMed1991

Gender differences in age effect on brain atrophy measured by magnetic resonance imaging.

A prospective sample of 69 healthy adults, age range 18-80 years, was studied with magnetic resonance imaging scans (T2 weighted, 5 mm thick) of the entire cranium. Volumes were obtained by a segmentation algorithm that uses proton density and T2 pixel values to correct field inhomogeneities ("shading"). Average (+/- SD) brain volume, excluding cerebellum, was 1090.91 ml (+/- 114.30; range, 822.19-1363.66), and cerebrospinal fluid (CSF) volume was 127.91 ml (+/- 57.62; range, 34.00-297.02). Brain volume was higher (by 5 ml) in the right hemisphere (P less than 0.0001). Men (n = 34) had 91 ml higher brain and 20 ml higher CSF volume than women (n = 35). Age was negatively correlated with brain volume [r(67) = -0.32, P less than 0.01] and positively correlated with CSF volume (r = 0.74, P less than 0.0001). The slope of the regression line with age for CSF was steeper for men than women (P = 0.03). This difference in slopes was significant for sulcal (P less than 0.0001), but not ventricular, CSF. The greatest amount of atrophy in elderly men was in the left hemisphere, whereas in women age effects were symmetric. The findings may point to neuroanatomic substrates of hemispheric specialization and gender differences in age-related changes in brain function. They suggest that women are less vulnerable to age-related changes in mental abilities, whereas men are particularly susceptible to aging effects on left hemispheric functions.

Adult↗
PubMed1991

Magnetic resonance imaging in schizophrenia. I. Volumetric analysis of brain and cerebrospinal fluid.

The study reports magnetic resonance imaging data for 42 patients with schizophrenia and 43 normal controls. Volumetric measures were obtained with a validated computerized algorithm for segmentation of cranial volume into brain tissue and central and peripheral cerebrospinal fluid (CSF), with high inter-operator reliability. Patients did not differ significantly in whole-brain volume, but had higher whole-brain CSF volume and higher ratios of ventricular and sulcal CSF to cranial volume. Covarying age and education did not affect the differences. However, there was considerable overlap both in CSF volumes and in volume-cranium ratios, and most patients were within the normal range. This suggests that anatomic changes reflected in CSF can provide a limited substrate for schizophrenia and may apply only to subpopulations. Although there was no gender x diagnosis interaction, the results for sulcal CSF were significant only for men, whereas for women, the ventricular ratios were marginally higher in patients.

Adolescent↗
PubMed1991

Neuropsychological function in schizophrenia. Selective impairment in memory and learning.

Unmedicated schizophrenic patients (according to DSM-III-R criteria) (n = 36) and age-matched normal controls (n = 36), balanced for parental socioeconomic status, were administered a battery of standardized neuropsychological tests. Patients showed generalized impairment relative to controls and a selective deficit in memory and learning compared with other functions. Selective impairment was not found on tests related to frontal system function (abstraction, verbal fluency, and motor). The observed pattern is consistent with greater involvement of the temporal-hippocampal system, against the background of diffuse dysfunction. Although impairment in memory and learning has been reported, the selectivity and relative severity compared with other behavioral functions have not been recognized. The specificity of this profile merits further examination. These findings lend support to the hypothesized importance of the temporal-hippocampal region in understanding the pathophysiology of schizophrenia.

Adult↗
PubMed1991

UAF radiorespirometric protocol for assessing hydrocarbon mineralization potential in environmental samples.

Following the EXXON Valdez oil spill, a radiorespirometric protocol was developed at the University of Alaska Fairbanks (UAF) to assess the potential for microorganisms in coastal waters and sediments to degrade hydrocarbons. The use of bioremediation to assist in oil spill cleanup operations required microbial bioassays to establish that addition of nitrogen and phosphorus would enhance biodegradation. A technique assessing 1-14C-n-hexadecane mineralization in seawater or nutrient rich sediment suspensions was used for both of these measurements. Hydrocarbon-degradation potentials were determined by measuring mineralization associated with sediment microorganisms in sediment suspended in sterilized seawater and/or marine Bushnell-Haas broth. Production of 14CO2 and CO2 was easily detectable during the first 48 hours with added hexadecane levels ranging from 10 to 500 mg/l of suspension and dependent on the biomass of hydrocarbon degraders, the hydrocarbon-oxidation potential of the biomass and nutrient availability. In addition to assessment of the hydrocarbon-degrading potential of environmental samples, the radiorespirometric procedure, and concomitant measurement of microbial biomass, has utility as an indicator of hydrocarbon contamination of soils, aqueous sediments and water, and can also be used to evaluate the effectiveness of bioremediation treatments.

Biodegradation, Environmental↗
PubMed1991

Analysis of brain and cerebrospinal fluid volumes with MR imaging. Part I. Methods, reliability, and validation.

A computerized system was developed to process standard spin-echo magnetic resonance (MR) imaging data for estimation of brain parenchyma and cerebrospinal fluid (CSF) volumes. In phantom experiments, the estimated volumes corresponded closely to the true volumes (r = .998), with a mean error less than 1.0 cm3 (for phantom volumes ranging from 5 to 35 cm3), with excellent intra- and interobserver reliability. In a clinical validation study with actual brain images of 10 human subjects, the average coefficient of variation between observers for the measurement of absolute brain and CSF volumes was 1.2% and 6.4%, respectively. The intraclass correlations for three expert operators is greater than .99 in the measurement of brain and ventricular volumes and greater than .94 for total CSF volume. Therefore, the authors believe that their technique to analyze MR images of the brain performed with acceptable levels of accuracy and reliability and that it can be used to measure brain and CSF volumes for clinical research. This technique could be helpful in the correlation of neuroanatomic measurements to behavioral and physiologic parameters in neuropsychiatric disorders.

Algorithms↗