Comprehensive evaluation of left hemisphere type I schizencephaly

We report the neuropsychological, magnetic resonance imaging, electroencephalographic telemetry, and sodium amytal test findings of a 32-year-old, left-handed man with unilateral left hemisphere type I schizencephaly. The patient was referred for treatment of medically refractory left temporal complex partial seizures that developed at age 26 years. Sodium amytal testing revealed complete incorporation of speech and language function by the right hemisphere. Detailed neuropsychological evaluation indicated average to above-average performance on all measures of language skills, judgment and reasoning, visuospatial abilities, and memory function. This case demonstrates that extensive but lateralized neuronal migration disorders can be associated with complete reorganization and full recovery of function by the contralateral hemisphere. Furthermore, this case supports the view that the degree of recovery is greatest when compensatory mechanisms are activated antenatally.

Regulation of growth-associated protein 43 (GAP-43) messenger RNA associated with plastic change in the adult rat barrel receptor complex

Plastic change occurs in the adult rat barrel receptor complex following peripheral deafferentation by removal of facial vibrissae (vibrissectomy) and can be prevented by prior depletion of brain norepinephrine. Growth-associated protein (GAP-43, B50, F1, pp46), a marker for synaptic reorganization, increases in the barrel cortex of adult rats following both peripheral and central deafferentation. Here we followed changes in GAP-43 mRNA expression in the barrel receptor system following vibrissectomy. Adult rats had unilateral total vibrissectomy with sparing of the central (C3) vibrissa. By in situ hybridization, GAP-43 mRNA first increased at 24h (9%, P < 0.05) in the ipsilateral trigeminal complex. Levels remained elevated (up to 25% of the unlesioned side) over the next 6 days, decreased to 88% at 7 days and returned to control levels at 14 days. Contralateral barrel cortex levels of GAP-43 mRNA increased by 14% at 4-5 days remained elevated through 7 days and returned to control levels by 14 days. Increased GAP-43 mRNA levels 6 days after vibrissectomy were reproduced by complete transection of the infraorbital nerve and were blocked by depletion of brain norepinephrine. No change occurred in ventrobasal thalamus GAP-43 mRNA at any time. Dot blot and Northern blot hybridizations of GAP-43 mRNA after vibrissectomy showed a 43% increase in the ipsilateral trigeminal complex and a 16% increase in the contralateral barrel cortex at 3 days and an 84% increase in ipsilateral trigeminal and 50% increase in contralateral barrel cortex GAP-43 mRNA at 6 days, respectively. Thus, deafferentation-induced plasticity in the barrel pathway depends upon norepinephrine and is associated with increase in both GAP-43 mRNA and protein suggesting that this may involve a structural change.

Differential effects of aging on two verbal fluency tasks

The effect of age on verbal fluency was studied in 84 healthy volunteers, ages 45 to 91 years, who performed letter-fluency and semantic-fluency tasks. Older subjects (75 to 91 yr.) performed as well as younger (50 to 64 yr.) on letter fluency but did significantly worse on semantic category fluency. This pattern is similar to that observed in Alzheimer-type dementia.

Selective increase in the right hemisphere transcranial Doppler velocity during a spatial task

Transcranial Doppler ultrasonography of the middle cerebral arteries was performed during two tasks: sorting of mah-jongg tiles and vibratory stimulation. These tasks selectively increase cerebral blood flow by positron emission tomography. The purpose of this study was to determine if analogous increases in cerebral blood flow velocity could be detected. We measured flow velocity during right hand manipulation followed by left hand manipulation, or vice versa, with resting studies in between. The average increase in the mean velocity, by paired t-test, was significant for the right middle cerebral artery with both left hand (p < .0005) and right hand (p < .005) tile sorting. For the left middle cerebral artery, there was an increase in the mean velocity with right hand (p < .005) but not for left hand sorting (p = .13). These findings support the importance of the right hemisphere in the performance of this type of spatial task. No significant flow velocity increase occurred during vibratory stimulation.

Defective glucoregulation of brain alpha 2-adrenoceptors in obesity-prone rats

Only half the male Sprague-Dawley rats fed high-energy diets develop diet-induced obesity (DIO); the rest are diet resistant (DR). It has been established that rats prone to develop DIO have decreased basal brain alpha 2-adrenoceptor levels compared with DR-prone rats and that DIO- but not DR-prone rats show glucose-induced increases in plasma norepinephrine (NE) levels. Because it has also been shown that alpha 2-adrenoceptors modulate ingestive and autonomic functions and are responsive to changes in plasma glucose levels, we tested the hypothesis that DIO- and DR-prone rats would regulate these receptors differently by using hyperinsulinemic clamping to vary plasma glucose levels. Rats with low glucose-induced plasma NE responses (DR-prone) showed significant positive correlations (r = 0.724-0.919) between plasma glucose levels and alpha 2-adrenoceptor ([3H]paraminoclonidine) binding in 5 of 17 brain areas (anterior, ventromedial, and arcuate hypothalamic nucleus; medial and basomedial amygdalar nucleus) assessed by autoradiographic techniques. Near-significant correlations were also seen in the paraventricular nucleus and lateral hypothalamus. High glucose-induced NE responders (DIO-prone) showed such a correlation only in the arcuate nucleus (r = 0.726). There was little glucoregulation of alpha 1-adrenoceptors. The defective ability of DIO-prone rats to alter brain alpha 2-adrenoceptors to changes in plasma glucose levels might underlie their predisposition to become obese on diets high in sucrose.

Adult familial dyslexia: a retrospective developmental and psychosocial profile

This study investigated the developmental, demographic, educational, and psychosocial outcome of 36 adults with third-generation familial dyslexia. Control subjects were 44 unaffected age-matched family members. Compared with control subjects, those with familial dyslexia 1) had similar incidences of perinatal complications, left-handedness, and right-left confusion but reported more early speech/language problems; 2) performed worse in reading and spelling but had similar educational achievement; 3) were more likely to report depression/anxiety symptoms and to have attention-deficit disorder with hyperactivity; and 4) were similar in medical history, marital stability, and mean income. Data suggest that, despite continued isolated reading deficits, carefully selected subjects with adult familial dyslexia do not show the previously described downward course of the learning-disabled population.

Glycosylation and membrane insertion of newly synthesized rat dopamine beta-hydroxylase in a cell-free system without signal cleavage

Dopamine beta-hydroxylase (DBH, EC 1.14.17.1) is present in both membrane-bound and soluble forms in neurosecretory vesicles. This study was designed to investigate the differences between membrane-bound and soluble DBH and how they may arise from translation of a single mRNA. Antisera to a peptide corresponding to the carboxyl terminus of rat DBH was found to specifically immunoprecipitate the 77- and 73-kDa subunits of newly synthesized DBH in rat brain. Thus, both soluble and membrane-bound forms contain the same carboxyl terminus. To investigate differences at the amino terminus, full-length rat DBH mRNA, translated in a cell-free system, produced a 66-kDa peptide. An additional higher molecular mass product was synthesized upon co-translational addition of microsomal membranes. This product was glycosylated since it bound to concanavalin A-Sepharose and reverted to the 66-kDa polypeptide after treatment with endoglycosidase H. This glycosylated product was resistant to protease digestion and fractionated with microsomal membranes on sucrose gradients, indicating that it is incorporated into the microsomal membranes. Amino-terminal sequencing of the glycosylated translation product indicated that the amino-terminal "signal" sequence was not cleaved. The results indicate that in the cell-free system newly synthesized DBH undergoes glycosylation and incorporation into microsomal membranes without cleavage of the NH2-terminal signal sequence.

Temporal lobectomy for seizures associated with unilateral schizencephaly

Schizencephaly is characterized by unilateral or bilateral cerebral clefts associated with neurologic deficits and epilepsy. Most commonly schizencephaly is attributed to abnormal neuronal migration, and these malformations are well visualized by current neuroimaging techniques. This report describes a patient with unilateral schizencephaly and poorly controlled complex partial seizures who was found to have a temporal lobe seizure focus; anterior temporal lobectomy produced nearly complete control of the seizures. Despite the extensive malformation, relatively restricted resection was of significant benefit. The principles of seizure focus localization and resection are applicable to the management of patients with schizencephaly.

Intracarotid glucose induced norepinephrine response and the development of diet induced obesity

Intracarotid glucose infusions cause increased plasma norepinephrine (NE) levels in some rats. This is used as an index of sympathetic activation. Similar increases in plasma NE levels are produced by intravenous glucose injections and these levels correlate positively with the amount of weight gained by adult rats when they are subsequently fed a diet enriched in calories, sucrose and fat (condensed milk (CM) diet) for three months. Thus, rats prone to develop diet induced obesity (DIO) on the CM diet have greater intravenous glucose induced NE responses than those which are diet resistant (DR). To test the hypothesis that this relationship is mediated by the brain, 17 chow fed, adult male Sprague-Dawley rats were infused for 60 min with intracarotid glucose at 4 mg/kg/min and blood samples were obtained for plasma catecholamines, insulin and glucose. They were then placed on the CM diet for three months. After three months on the CM diet, there was a wide variability in body weight gain and the weights of retroperitoneal fat pads, an indirect measure of carcass adiposity. For all 17 rats, there was a significant correlation between both body weight gain (r = 0.685, P = 0.002) and retroperitoneal fat pad weights (r = 0.590, P = 0.013) with the levels of plasma NE reached 45-60 min into the preceding intracarotid glucose infusions. For the six lowest and six highest glucose induced NE responders, the correlation between NE response and body weight gain on CM diet was r = 0.944 (P = 0.0001). Plasma epinephrine, insulin and glucose levels were unchanged during such infusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Cognitive impairments in Parkinson's disease

The clinical neuropsychologic profiles of patients with Parkinson's disease and patients with SDAT show both overlap and dissociation. Speech, language, and certain memory skills are examples of dissociable differences, especially in the early stages of the disease. Furthermore the presence of depression, evidence of cognitive slowing, and absence of aphasia in patients with Parkinson's disease suggest prominent subcortical involvement. It is probably premature to categorize all of the cognitive changes in patients with Parkinson's disease as subcortical, however. Some skills, such as visuospatial and executive functions, are impaired in both disorders, and although the etiologic bases for task failure may differ for each, this issue remains open-ended. Another problem is that often the evidence for or against the cortical/subcortical distinction is insufficient and in some cases based on a single measure thought to be representative of a given cognitive domain. Most importantly there are few comparative studies that provide unequivocal support for making a cortical/subcortical distinction. Failure to equate for level of cognitive impairment or functional disability between dementias and strict adherence to cross-sectional study designs further compromise efforts to characterize each syndrome precisely. Whitehouse suggested that a prospective study of several different dementias studied in parallel, examining a wide range of cognitive skills, is required before the cortical/subcortical classification scheme can be validated. A critical component is an autopsy program to confirm diagnoses and provide clinicopathologic correlation. It is possible that the diverse nature of the cognitive impairment in patients with Parkinson's disease is not a methodologic artifact but reflects multiple disease subtypes. Ross, Mahler, and Cummings proposed three dementia syndromes in patients with Parkinson's disease: one that is relatively mild and meets the criteria for subcortical dementia, a second that is more severe and shows a wider range of cognitive impairment but is still neuropathologically distinct from SDAT, and a third severe dementia with both subcortical and cortical involvement that may reflect basal ganglia and Alzheimer-type pathology.

Vibrissectomy induced changes in GAP-43 immunoreactivity in the adult rat barrel cortex

Within the rat primary somatosensory cortex, neurons responding principally to movement of each individual mystacial vibrissa are grouped together in structures termed barrels. Previous studies have examined changes in the area of cortex showing increased 2-deoxyglucose uptake in response to vibrissal stimulation. These studies have shown that chronic removal of all but the central (C3) vibrissa in adult rats induces an enlarged representation of the remaining C3 barrel in the contralateral cortex. This increase is prevented by cortical norepinephrine depletion. The major question raised by such studies is whether such plasticity is due to structural rearrangement or unmasking of otherwise silent synapses. In this study, antibodies to GAP-43, a presynaptic protein whose synthesis is related to neuronal development and regeneration, were used to investigate this issue. In adult rat brain, tangential sections through layer IV of the barrel receptor field normally show moderate levels of GAP-43 immunoreactivity (GAP-IR) in the inter-barrel septa and low levels within the barrels themselves. The present study examined changes in the pattern of GAP-IR from 1 to 8 weeks after vibrissectomy with sparing of C3 as an index of possible physical reorganization of cortical circuits. Quantitative analysis of the cortices of animals with unilateral vibrissectomy with sparing of C3 showed that the area of low GAP-IR within the barrels surrounding C3 was decreased at 1 week (8.4% shrinkage; P less than 0.01) and 8 weeks (12.0% shrinkage; P less than 0.015), relative to the cortex ipsilateral to the surgery. Both bilateral vibrissectomy with sparing of C3 and ibotenic acid lesions of the ventrobasal thalamus produced similar results. Some evidence was also seen that the area of low GAP-IR in the C3 barrel shrank to a similar degree after such manipulations. Cortical norepinephrine depletion had no apparent effect on vibrissectomy-induced GAP-IR changes. These results suggest that removal of vibrissal input to the adult rat barrel cortex produces transynaptic induction of axonal sprouting within the barrel cortex.

Sequential cranial MR findings of asymptomatic and neurologically symptomatic HIV+ subjects

PURPOSE

To compare results of a prospective MR and clinical reevaluation of HIV+ asymptomatic and neurologically symptomatic subjects who had had initially abnormal cranial studies to determine what cranial MR changes occur and how these changes correlate with serial neurologic and neuropsychologic findings.

PATIENTS AND METHODS

Thirty-one asymptomatic (n = 20) and neurologically symptomatic (n = 11) subjects seropositive for the human immunodeficiency virus (HIV+) were prospectively reevaluated by cranial magnetic resonance (MR) one to two years following an initially abnormal MR of the brain.

RESULTS

All 31 HIV+ subjects with initial abnormal MR had abnormal follow-up scans (showing atrophy and/or white matter lesions). Twenty-seven showed no progression of MR abnormalities (among whom were 18 with minimally abnormal scans who remained asymptomatic with improved or static neuropsychologic performance). Of the four subjects with scan changes (all with clinically suspected HIV encephalopathy), one showed MR, clinical, and neuropsychologic test improvement; the remaining three showed MR (n = 3), neurologic (n = 3), neuropsychologic (n = 1) worsening and autopsy (n = 1) confirmed the presence of HIV-1 containing multinucleated giant cells in the brain.

CONCLUSIONS

This study suggests that: 1) Progression of intracranial MR abnormalities due to HIV-1 is seen only in a minority of HIV+ subjects over a 1- to 2-year time period, only in those neurologically symptomatic, and correlates with clinical deterioration. 2) Minor cerebral MR abnormalities seen in HIV+ subjects who remain neurologically asymptomatic do not change over a 1- to 2-year period. 3) Although HIV is known to infect the brain early, it may, nevertheless, not routinely do significant anatomical damage early on in the disease, as based on MR criteria.

Transcranial Doppler assessment of cerebral flow velocity during cognitive tasks

BACKGROUND AND PURPOSE

The purpose of this study was to assess the ability of transcranial Doppler ultrasonography to detect selective circulatory changes during cognitive activity.

METHODS

We measured cerebral artery flow velocity in 21 normal volunteers by transcranial Doppler ultrasonography during rest followed by cerebral activation. Mean and peak systolic flow velocities of the anterior, middle, and posterior cerebral arteries were measured during the performance of a commercial video game. We also measured flow velocity of the anterior cerebral arteries in 18 subjects during a mental arithmetic task. Serial measurements of the right and left sides were made with a headband with two probes.

RESULTS

We observed a global increase in the flow velocity above baseline measurements during task performance. During the video game, both middle cerebral arteries (t = 2.6, p = 0.02 for the left; t = 3.3, p = 0.004 for the right) and the left posterior cerebral artery (t = 2.2, p = 0.004) had selective increase in mean flow velocity compared with the ipsilateral anterior cerebral artery. This selective activation was most prominent in the right middle cerebral artery, which had a greater degree of activation than the right posterior cerebral artery (t = 2.8, p = 0.013). We did not observe a statistically significant difference between the right and left middle cerebral arteries, but there was a trend toward a greater activation on the right for both the mean velocity (t = 1.7, p = 0.098) and the peak velocity (t = 1.9, p = 0.079).

CONCLUSIONS

Our preliminary investigation suggests that this noninvasive technique has the potential to correlate selective cerebral artery flow dynamics with cognitive activity.

Glucose increases rat plasma norepinephrine levels by direct action on the brain

The hypothesis that glucose can selectively activate the sympathetic nervous system (SNS) by direct action on the brain was tested using plasma norepinephrine (NE) and epinephrine (Epi) responses to intracarotid and intravenous glucose injections as indexes of SNS and adrenal medullary responses, respectively. Intracarotid glucose bolus injections (0.1 g/kg) transiently raised plasma glucose (22%) and insulin (98%) levels at 2 min and increased plasma NE, but not Epi, levels from 2 to 60 min. Areas under the NE curve were 700% higher than equiosmolar doses of mannitol. An intravenous glucose bolus (1 g/kg) gave quantitatively similar but delayed (30 min) NE responses to the 0.1 g/kg intracarotid dose but raised plasma glucose 500% and insulin 1,700% above baseline at 2 min postinjection. Slow intracarotid glucose infusions for 60 min at 4 mg.kg-1.min-1 raised plasma NE levels from 30 to 60 min with 250% higher areas under the NE curve than the intracarotid and intravenous bolus doses but without a change in plasma glucose, insulin, or Epi levels. Infusions at 6 mg.kg-1.min-1 transiently raised plasma NE levels at 30 min without altering glucose, insulin, or Epi levels. These results suggest that glucose alone can produce a selective, delayed SNS activation by a direct action on the brain.

Defective cerebral glucose utilization in diet-induced obese rats

A neural mechanism may underlie the divergent weight gain patterns of rats fed a high-energy diet; half develop diet-induced obesity (DIO), whereas the rest are diet resistant (DR). Male rats were fed chow (n = 14) or a high-energy diet for 3 mo with the development of DIO (n = 11) or DR (n = 12). DIO rats had 159-219% heavier retroperitoneal fat pads and 158% higher plasma insulin levels than chow-fed and DR rats, but plasma glucose levels were equal. Rats were trained to drink glucose after an overnight fast and were tested for local cerebral glucose utilization using 2-deoxy-D-[14C]glucose autoradiography in the presence or absence of 0.15% saccharin substituted for glucose. Saccharin intake increased 2-deoxyglucose uptake in the rostral nucleus tractus solitarius of DR but not DIO or chow-fed rats. Also, DIO rats had reduced basal 2-deoxyglucose uptake in the central amygdaloid nucleus. High-energy diet intake was associated with saccharin-induced depression of 2-deoxyglucose uptake in the inferior olive and increased utilization in the medial amygdaloid nucleus of both DR and DIO rats. Thus DIO rats have diminished basal and food-related neuronal activity in certain brain areas involved in food intake and autonomic function. Furthermore, dietary content affects glucose utilization in areas not usually associated with these functions.

Spontaneous motor activity during the development and maintenance of diet-induced obesity in the rat

More than 80% of most daily spontaneous activities (assessed in an Omnitech activity monitor) occurred during the last hour of light and 12 h of the dark phase in 8 chow-fed male Sprague-Dawley rats. Thirty additional rats were, therefore, monitored over this 13-h period to assess the relationship of activity to the development and maintenance of diet-induced obesity (DIO) on a diet high in energy, fat and sucrose (CM diet). Nine of 20 rats became obese after 3 months on the CM diet, with 71% greater weight gain than 10 chow-fed controls. Eleven of 20 rats were diet resistant (DR), gaining the same amount of weight as chow-fed rats. Neither initial activity levels nor initial body weights on chow (Period I) differed significantly across retrospectively identified groups. After 3 months on CM diet or chow (Period II), as well as after an additional 3 months after CM diet-fed rats returned to chow (Period III), there were significant inverse correlations (r = -.606 to -.370) between body weight at the time of testing and various measures of movement in the horizontal plane. There was no relationship to dietary content nor consistent correlations of body weight or diet group to vertical movements, an indirect measure of ingestive behavior. Patterns of time spent in the vertical position were significantly different for DIO vs. DR rats in Period III, however. Thus, differences in food intake and metabolic efficiency, rather than differences in nocturnal activity, are probably responsible for the greater weight gain in DIO-prone rats placed on CM diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult rat barrel cortex plasticity occurs at 1 week but not at 1 day after vibrissectomy as demonstrated by the 2-deoxyglucose method

Stimulation of a single facial vibrissa in rats receiving [14C]2-deoxyglucose leads to increased local cerebral glucose utilization in the corresponding contralateral barrel of lamina IV of the first somatosensory cortex (SmI). In the adult rat, the metabolic representation of such a barrel enlarges 2 months after removal of all other vibrissal follicles but enlargement is prevented by prior removal of SmI norepinephrine. Here, the early time course of such enlargement and how this was affected by cortical norepinephrine manipulations were examined in adult rats. One day after total vibrissal follicle removal with sparing of the central (C3) vibrissa, neither the areal extent nor absolute glucose utilization in the stimulated, spared C3 cortical barrel were changed. However, 7 days after follicle removal, the spared C3 barrel was enlarged by 41%, although absolute glucose utilization remained constant. This delayed onset of enlargement is compatible with either a structural or neurochemical change in barrel circuitry following vibrissal deafferentation. With ipsilateral locus coeruleus lesions but intact vibrissae, there was progressive enlargement of stimulated C3 barrel areas with increasing cortical norepinephrine depletion (r = 0.864) suggesting a suppressive effect of norepinephrine on activity spread in barrels with intact vibrissal afferents. Previously shown blockade of chronic (2 month) vibrissectomy-induced barrel enlargement by norephinephrine depletion suggested an additional effect on plasticity. Even though acute (1 day) follicle removal here produced no change in spared C3 barrel area, addition of norepinephrine depletion produced a surprising 40% decrease in barrel area. Thus, barrel plasticity assessed by 2-deoxyglucose reflects a complex interaction between barrel metabolic activity and the extent of vibrissal and noradrenergic afferent input.

Visuospatial impairment in Parkinson's disease

We explored the nature of the visuospatial deficit in Parkinson's disease (PD) and its progression as a function of disease duration. We compared the performance of 183 patients with idiopathic PD and 90 control subjects matched for age and education on six visuospatial measures. We divided patients into three groups according to the disease duration: early (1 to 4 years), middle (5 to 10 years), and advanced (greater than 10 years). Performance deteriorated in five of the six visuospatial measures, as a function of disease duration. However, the pattern of visuospatial decline depended on whether dementia was present. The results were not influenced by age or anticholinergic medication. These findings support the presence of visuospatial deficits in PD patients, with a changing pattern of impairment related to dementia and progression of the disease.

Fetal neocortical transplants into the medial forebrain bundle attract ingrowth of catecholaminergic fibers in adult rat brain

The hypothesis that fetal tissue grafts may exert a trophic influence on damaged catecholaminergic fibers was examined. Ascending dopamine and norepinephrine axons normally innervate frontal cortex targets in the intact rat brain. These and other ascending catecholaminergic fibers were disrupted with stereotaxic injections of 6-hydroxydopamine into the medial forebrain bundle (mfb), followed after 1 or 14 days by grafts of fetal neocortical tissue placed into the injection site, or by sham grafts. Glyoxylic acid histofluorescence techniques were then used to examine catecholaminergic fiber distribution. When such lesions were made without subsequent grafting, virtually no growth of catecholaminergic fibers occurred beyond the injection site and frontal cortex norepinephrine levels were depleted to 15% of control levels. However, when grafts of fetal neocortical tissue were made into the lesion site and animals examined 3 months later, catecholaminergic fibers grew through the lesion site to ramify within the graft tissue. Catecholaminergic fibers were seen in all portions of most grafts, though they were most dense on the caudal and ventral edges of the graft, close to the path of the mfb. Similar densities of graft innervation were seen 3 months after animals received grafts placed into the same site without prior lesioning of catecholaminergic fibers. Fetal neocortical grafts thus induce collateral sprouting from intact host catecholaminergic axons and may also promote regenerative sprouting when such fibers are otherwise irreparably damaged.

A retrospective analysis of the effects of anticholinergic medication on memory performance in Parkinson's disease

We examined the effects of anticholinergic medication on memory function in 113 patients with idiopathic Parkinson's disease (PD). Subjects were divided into three disease duration groups: early, middle, and advanced. The battery consisted of three tasks assessing memory of logical discourse, semantically related words, and figural material. We found no evidence of anticholinergic-induced memory dysfunction in any of the three groups. Analysis of covariance indicated that age was not a significant variable; however, dementia may have influenced the relationship between anticholinergic medication and memory scores. Our results indicate that anticholinergic medication does not uniformly compromise memory function in PD patients.

Are all subcortical dementias alike? Verbal learning and memory in Parkinson's and Huntington's disease patients

The utility of the concept of 'subcortical dementia' was investigated by comparing the verbal learning and memory abilities of Parkinson's disease (PD) patients with those of Huntington's disease (HD) patients. Many similarities between the PD and HD groups emerged, including impaired immediate memory spans, inconsistency of recall across learning trials, deficient use of a semantic clustering learning strategy, elevated intrusion rates on delayed recall, impaired recognition memory performance, normal retention of information over delay periods, normal vulnerability to proactive or retroactive interference, and normal types of intrusion errors. The HD subjects, however, displayed inferior free recall, deficient improvement across learning trials, abnormal serial position recall effects, higher perseveration rates, and supranormal improvement on recognition testing compared with free recall. Implications of these results for characterizing memory deficits associated with subcortical system dysfunction are discussed.

Effects of dehydroepiandrosterone treatment in rats with diet-induced obesity

Previous studies showed that administration of dehydroepiandrosterone (DHEA) to lean and genetically obese Zucker rats reduced body weight. In the present experiments, the effect of DHEA treatment in rats with diet-induced obesity was evaluated. In experiment 1, male Sprague-Dawley rats (300 g) were fed a nonpurified diet (reference group) or a condensed milk-corn oil nonpurified diet [diet-induced obese (DIO) rats] for 7 wk. Then, 0.6% DHEA was included in the food of one-half of the DIO rats (DIO + DHEA rats). After 6 wk, DIO rats weighed 23% more and had greater fat pad weights, cell size and cell number than reference and DIO + DHEA rats. Brown fat mitochondrial respiration was similar in all groups. DIO rats had higher serum cholesterol and triacylglycerol concentrations than reference and DIO + DHEA rats. DIO + DHEA rats had lower serum insulin levels than DIO and reference rats. In experiment 2, male Sprague-Dawley rats (460 g) were fed either the nonpurified diet or the condensed milk diet for 8 wk. Condensed milk-fed rats were then divided into DIO and diet-resistant groups. One-half of the rats in each group were fed 0.6% DHEA for 2 wk. Body weights and serum glucose, insulin, triacylglycerol and triiodothyronine levels were lowered by DHEA treatment in all groups. Liver mitochondrial state 3 respiration rates per gram and per liver and peroxisomal beta-oxidation were higher in DHEA-treated than in control rats. In DIO rats, DHEA treatment appears to interfere with hyperplastic adipose tissue growth. In this strain of rats, DHEA appears to have hypolipidemic and hypoinsulinemic effects.