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Biomedical subjects

L Friedman

Publications and source records attributed to L Friedman.

At least 145 records · Page 8Linked to original sources
PubMed1993

Improvement in cognitive functions and psychiatric symptoms in treatment-refractory schizophrenic patients receiving clozapine.

Cognitive functions and psychopathology were assessed in 36 treatment-refractory schizophrenic patients before initiation of clozapine, and at 6 weeks and 6 months, thereafter. Before treatment, cognitive impairment was found in each measure of memory, attention, and executive function as compared with 26 normal controls. After both 6 weeks and 6 months of treatment, significant improvement occurred in the Controlled Oral Word Association Test, a measure of retrieval from reference memory. Improvement was also noted at 6 months in the Category Instance Generation Test, another measure of retrieval from reference memory, and in some, but not all, tests of executive function, attention, and recall memory. Clozapine treatment also resulted in significant improvement in Brief Psychiatric Rating Scale (BPRS) Total and Positive symptom scores at both 6-week and 6-month assessment points. There was some evidence for a relationship between improvement in psychopathology and cognitive function. The improvement in cognitive function during clozapine treatment could have consequences for capacity to work and social function.

Adult↗
PubMed1993

Depression as a confounding variable in the estimation of habitual sleep time.

Self-reported habitual sleep time is an important variable because short and long sleep times are associated with mortality. Speculation with regard to these results usually focuses on physical health, rather than psychological factors. We investigated the role of anxiety and depression in reports of habitual sleep times by examining the relative and absolute discrepancy between individuals' initial estimates of their sleep times and sleep diaries made over a 2-week period. Results indicated that depressed mood was associated not only with a tendency initially to underestimate length of sleep (relative discrepancy), but also to exaggerate reported sleep time regardless of direction (absolute discrepancy). These results imply that studies that examine relationships between reported sleep times and mortality should take mental health factors into account.

Aged↗
PubMed1993

Identification of vascular structures as a major source of signal contrast in high resolution 2D and 3D functional activation imaging of the motor cortex at 1.5T: preliminary results.

We have measured the T2* signal response associated with cortical activation due to finger motion at 1.5 Tesla. Both thin slice 2D and 3D images show signal intensity changes which vary from 2% to 32% depending on volunteer, echo time, slice thickness, and in-plane resolution. The largest signal change occurred for the thinnest slices and highest resolution (2 mm3). This is consistent with reducing partial volume effects and a simple difference in phase between the intravascular signal and surrounding parenchyma. No inflow enhancement was seen on the 2D or 3D scans, confirming the nature of the signal difference for this approach was due to local field inhomogeneity effects. Using 3D imaging, multiple effects can be seen simultaneously. With a 3D MRA method, it was possible to locate the vessel that was the source of the T2* behavior; it was in each case a vein on the surface of the cortical parenchyma.

Brain↗
PubMed1993

The NHLBI model: a 25 year history.

Although newer techniques and procedures have been developed, many of the clinical trial design and monitoring concepts used today in the NHLBI were implemented 25 years ago. Among these are the organizational structure of multicentre trials and the use of an independent data monitoring committee. Examples of data monitoring committee discussions and decisions are provided.

Clinical Trials as Topic↗
PubMed1993

High-density genetic map of the BRCA1 region of chromosome 17q12-q21.

To facilitate the positional cloning of the breast-ovarian cancer gene BRCA1, we constructed a high-density genetic map of the 8.3-cM interval between D17S250 and GIP on chromosome 17q12-q21. Markers were mapped by linkage in the CEPH and in extended kindreds in our breast cancer series. The map comprises 33 ordered polymorphisms, including 12 genes and 21 anonymous markers, yielding an average of one polymorphism every 250 kb. Twenty-five of the markers are PCR-based systems. The order of polymorphic genes and markers is cen-D17S250-D17S518-HER2-THRA1-RARA-D17S80 -KRT10-[D17S800-D17S857]-GAS- D17S856-EDH17B-D17S855-D17S859-D17S858-[++ +PPY-D17S78]-D17S183-EPB3-D17S579- D17S509-[D17S508-D17S190 = D17S810]-D17S791-[D17S181 = D17S806]-D17S797- HOX2B-GP3A-[D17S507 = GIP]-qter. BRCA1 lies in the middle of the interval, between THRA1 and D17S183. Markers from this map can be used to determine whether cancer is linked to BRCA1 in families, to evaluate whether tumors have lost heterozygosity at loci in the region, and to identify probes for characterizing chromosomal rearrangements from patients and from tumors.

Alleles↗
PubMed1993

A study of the problems older adults encounter when using a mnemonic technique.

This study explored problems older adults experience when using a mnemonic technique known as the method of loci. Older subjects received six hours of imagery, judgment, and relaxation pretraining followed by mnemonic training for either four or six hours (Regular or Extended training, respectively). At the end of training, subjects were given a list of the constituent steps of the method of loci and asked to indicate which, if any, were problematic. The factor structure of the relations among the problems varied according to the length of the training subjects received. Specifically, the factor structure of the difficulties reported by the Regular training group reflected problems with using the steps involved in the application of the method of loci, whereas for the Extended training group the factor structure reflected problems with abilities called upon in using the technique. Thus, even with Extended training, subjects may need additional pretraining to develop specific abilities necessary for the successful application of the mnemonic.

Aged↗
PubMed1993

Cognitive decline in Alzheimer's disease: elaborating on the nature of the longitudinal factor structure of the Mini-Mental State Examination.

The purpose of this paper was to use the Wechsler Adult Intelligence Scale (WAIS) to further define the nature of the underlying factors of the Mini-Mental State Examination (MMSE) as proposed by Tinklenberg et al. (1990). The MMSE was administered to 51 patients once every 6 months for at least one year; the WAIS was administered only at the beginning of the study. Stepwise regression analyses yielded these results: for the Following Commands factor, the best correlate was the Comprehension subtest; for the Language Repetition factor, the best correlate was the Picture Arrangement subtest; and for the Language Expression factor, the best correlates were the Digit Symbol and Object Assembly subtests. These relations help clarify the correlates of decline of AD patients on the MMSE.

Aged↗
PubMed1993

Typography manipulations can affect priming of word stem completion in older and younger adults.

The experiments reported here investigated whether changes of typography affected priming of word stem completion performance in older and younger adults. Across all experiments, the typeface in which a word appeared at presentation either did or did not match that of its 3-letter stem at test. In Experiment 1, no significant evidence of a typography effect was found when words were presented with a sentence judgment or letter judgment task. However, subsequent experiments revealed that, in both older and younger adults, only words presented with a syllable judgment task gave rise to the typography effect (Experiments 2-4). Specifically, performance was greater, when the presentation and test typeface matched than when they did not. Experiment 5, which used stem-cued recall, did not reveal a difference between syllable and letter judgment tasks. These findings highlight the complex nature of word stem completion performance.

Age Factors↗
PubMed1993

Spontaneous mnemonic strategies used by older and younger adults to remember proper names.

Little attention has been focused on the spontaneous mnemonic strategies that people use to remember proper names. In the experiment reported here, groups of younger (< 25 years old) and older subjects (> or = 55 years old) were shown a series of 12 name-face pairs and instructed to remember them. In a subsequent test, they were shown the same faces and asked to recall the corresponding names. After the recall task, subjects completed a questionnaire about the mnemonic strategies they used. Our analyses revealed not only that the younger subjects recalled more names than did the older subjects, but also that older and younger subjects reported using certain strategies more frequently than other strategies. Moreover, regression analyses indicated that use of certain mnemonic strategies accounted for a significant proportion of recall performance beyond that accounted for by age alone. Older-old subjects (> or = 70 years old) recalled fewer names than did younger-old subjects (> or = 55 and < 70 years old), but they did not differ in the extent to which they used specific mnemonic strategies. Our results suggest that the use of spontaneous mnemonic strategies may play a role in the difference in proper name recall between younger and older adults.

Adult↗
PubMed1993

Use of the wrist actigraph to study insomnia in older adults.

Measures derived from the wrist actigraph have been found to correlate highly with EEG measures of normal sleep. Although the actigraph has been used to study normal sleep, few studies have used the actigraph as a measure of sleep of elderly insomniacs. The present study, which used elderly insomniacs, sought to investigate the sensitivity of the actigraph to detect the effects of an insomnia treatment. The actigraph was sufficiently sensitive to detect the effect of the sleep restriction therapy used on several sleep measures. Subsidiary analyses suggested that the sleep log, although not an accurate measure of sleep, may be useful as a measure of elderly insomniacs' subjective perception of sleep. Because the actigraph can be used more easily and less expensively than the polysomnogram, the actigraph appears to be a promising measure for assessing the efficacy of treatment interventions in elderly insomniacs.

Aged↗
PubMed1993

A limited, low-dose computed tomography protocol to examine the sacroiliac joints.

Limited, low-dose, three-scan computed tomography (CT) was shown to be as accurate as a complete CT series in examining the sacroiliac joints and is suggested as an effective alternative to plain radiography as the primary means to detect sacroiliitis. The advantages include the brevity of the examination, a 2-fold to 4-fold reduction in radiation exposure relative to conventional radiography and a 20-fold to 30-fold reduction relative to a full CT series. The technique was developed from studies of anatomic specimens in which the articular surfaces were covered with a film of barium to show clearly the synovial surfaces and allow the choice of the most appropriate levels of section. From the anteroposterior scout view the following levels were defined: at the first sacral foramen, between the first and second sacral foramina and at the third sacral foramen. In the superior section a quarter of the sacroiliac joint is synovial, whereas in the inferior section the entire joint is synovial. The three representative cuts and the anteroposterior scout view are displayed on a single 14 x 17 in. (36 x 43 cm) film. Comparative images at various current strengths showed that at lower currents than conventionally used no diagnostic information was lost, despite a slight increase in noise. The referring physicians at the authors' institution prefer this protocol to the imaging routine previously used.

Arthritis↗
PubMed1993

Gamma-aminobutyric acidA receptor regulation: chronic treatment with pregnanolone uncouples allosteric interactions between steroid and benzodiazepine recognition sites.

Pregnanolone [5 beta-pregnan-3 alpha-ol-20-one (5 beta 3 alpha)] and allopregnanolone [5 alpha-pregnan-3 alpha-ol-20-one (5 alpha 3 alpha)] are neuroactive steroids that are reduced metabolites of progesterone. Both 5 beta 3 alpha and 5 alpha 3 alpha are potent positive modulators of the gamma-aminobutyric acid response that enhance the binding of [3H]flunitrazepam ([3H] FNZ) to the gamma-aminobutyric acid type A receptor. Chronic (48 hr) exposure of brain neurons in culture to 5 beta 3 alpha or 5 alpha 3 alpha abolishes potentiation of [3H]FNZ binding by these steroids. This uncoupling, or loss of allosteric interactions between steroid and benzodiazepine recognition sites, is dose dependent, stereospecific, and reversible. The number and affinity of [3H]FNZ binding sites are unaffected. In contrast, the steroids 5 beta-pregnan-3 beta-ol-20-one, beta-estradiol, testosterone, progesterone, deoxycorticosterone, and dexamethasone, which show little capacity to potentiate [3H]FNZ binding, are also much less effective in inducing uncoupling of steroid and benzodiazepine recognition sites. These results suggest a mechanism whereby neurons could become refractory to long term modulation by neuroactive steroids. The results are discussed in terms of their possible relevance to premenstrual anxiety and enhanced frequency of seizures in certain women.

Allosteric Site↗
PubMed1993

The effect of dopamine on graft function in patients undergoing renal transplantation.

We studied the effect of a low-dose dopamine infusion on graft function in 60 patients undergoing transplantation with cadaveric kidneys in a prospective controlled trial. Recipients were allocated to either a control or a dopamine group, the latter receiving a 3 micrograms.kg-1 x min-1 infusion of dopamine starting intraoperatively. Evaluation of dopamine's effect was undertaken in two stages, namely, (i) initial graft function 1 wk after transplantation and (ii) graft survival at 3 mo. Initial graft function was determined by the ability of the transplanted kidney to reduce serum creatinine, and the development of acute tubular necrosis as confirmed by renal biopsy. Of the dopamine group 33.3% developed acute tubular necrosis compared to 23.3% of the control group. The second-stage evaluation was based on plasma creatinine levels and the requirement for dialysis within 3 mo of transplantation. 92.8% of the dopamine group and 76.9% of the control group had good graft function. No statistically significant difference between the two groups was found. The perioperative infusion of dopamine at 3 micrograms.kg-1 x min-1 was not shown to have any beneficial effect on the transplanted kidney in patients who do not have serious vascular disease, or who do not receive kidneys subjected to prolonged hypotension or prolonged preservation or anastomotic times.

Adolescent↗
PubMed1993

Nonlinear statistical models for the joint action of toxins.

A general approach using nonlinear regression models is presented for evaluating additivity, synergism, and antagonism of mixtures of toxins for proportions and ratio-scale response measures. This approach provides several advantages over the analysis methods typically used, which involve linear regression with logits or probits. A single model fit is performed, rather than a multistep procedure. Nonadditive alternative models can be easily constructed and tested against the appropriate additive models. The approach avoids the use of data "adjustments" for nonzero background response rates. The analyses are performed in the natural response metric, making interpretation straightforward. Also, the nonlinear regression model can be reparameterized to provide more meaningful primary parameters.

Animals↗
PubMed1992

Saccadic intrusions into smooth pursuit in patients with schizophrenia or affective disorder and normal controls.

Two types of saccadic intrusions into smooth pursuit eye tracking, anticipatory saccades (AS), and square wave jerks (SWJ), were measured in 23 patients with schizophrenia, 16 patients with affective disorder, and 21 normal controls. Constant velocity (5 degrees and 20 degrees/sec) predictable targets were employed. High resolution infrared oculography was employed to record eye movements. Although most subjects had at least one SWJ, there were no significant group differences, and the highest individual rates of SWJ were seen in the normal control group. On the other hand, AS were never seen in normals, but were present in 25%-44% of patients with either schizophrenia or affective disorder. Both patient groups had significantly more AS than controls, but the two patient groups were not significantly different.

Adult↗