Local blood flow and vascular permeability of autonomic ganglion-transplants in the brain.

The purpose of this study was to determine whether the blood vessels of transplanted neural tissue retain their functional characteristics. Quantitative autoradiography was used to measure local blood flow (F) with iodoantipyrine and the blood-to-tissue transfer constant (K) with alpha-aminoisobutyric acid in superior cervical ganglion (SCG) allografted to the surface of ventricle IV and into the cerebellum of the same rat. The F of the intraparenchymal grafts was slightly lower than that of the intraventricular grafts; F decreased between 1 and 4 weeks in SCG grafts at both sites.

Magnetoencephalography and epilepsy research.

Magnetoencephalography is the detection of the magnetic field distribution across the surface of the head, which is generated by a neuronal discharge within the brain. Magnetoencephalography is used in clinical epilepsy to localize the epileptogenic region prior to its surgical removal. A discussion of the instrumentation based on the superconducting quantum interference device that is used for detecting the magnetic field distribution, the analytical techniques, current research, and future directions of magnetoencephalography in epilepsy research is presented.

Hydrodynamic properties of the gonadotropin receptor from a murine Leydig tumor cell line are altered by desensitization.

The murine Leydig tumor cell line 1 (MLTC-1) contains gonadotropin receptors (GR) that are coupled to adenylate cyclase through the stimulatory guanine nucleotide binding protein (Gs). The binding of human choriogonadotropin (hCG) causes MLTC-1 cells to accumulate cAMP. With time, the ability of MLTC-1 cells to respond to hCG is attenuated by a process called desensitization.

Tetrahydroaminoacridine blocks voltage-dependent ion channels in hippocampal neurons.

Tetrahydroaminoacridine (THA) is a centrally active anticholinesterase that may produce functional improvement in patients with Alzheimer's disease. Because of its structural similarity to the potassium channel (A-current) blocking drug 4-aminopyridine (4-AP), it has been speculated that some of the therapeutic benefit of THA might result from inhibition of potassium currents. In the present study, THA produced a dose-dependent, reversible block of the A-current in cultured hippocampal neurons (IC50, 30 microM).

Cross-correlation of EMG reveals widespread synchronization of motor units during some slow movements in intact cats.

It is commonly assumed that the motor units comprising a single mammalian muscle will be recruited asynchronously at subtetanic firing rates to produce smoothly modulated force output. However, electromyograms from certain neck muscles, recorded by implanted bipolar "patch" electrodes having large contacts, often exhibited a rhythmic clustering of spike activity whose patterns suggested that motor-unit firing was synchronized both within and across muscles. We have developed a computerized processing system that digitizes EMG activity and calculates auto- and cross-correlation products of selected segments.

A multiple-contact EMG recording array for mapping single muscle unit territories.

The glycogen-depletion technique has become a well-established method for determining histologically the cross-sectional distribution of a single muscle unit. A major drawback of this method is its low yield of one depleted unit per experiment. Furthermore, this technique is particularly unsuited for determining the longitudinal distribution of single muscle units in long, broad muscles because of the formidable serial sectioning job that would be required.

Schmidt-Lanterman clefts: a morphometric study in human sural nerve.

In the human sural nerve, large myelinated fibers contained 35 Schmidt-Lanterman (SL) clefts per mm, and small myelinated fibers contained only eight SL clefts per mm. The incidence of SL clefts is linearly related to myelin thickness. The SL clefts extended over 13 micron in large and over 9 micron in small fibers, the total extent of the SL region amounting to nearly 50% of internodal length in large and to 6% in small fibers.

Inhibition of protein synthesis prolongs Ca2+-mediated reduction of K+ currents in molluscan neurons.

Elevated intracellular Ca2+ concentration within the Hermissenda type B cell has previously been shown to cause transient reduction of both the early K+ current IA and the delayed, Ca2+-dependent K+ current ICa2+-K+, a reduction that is more permanent with classical conditioning. Other earlier experiments suggested that Ca2+-mediated reduction of K+ currents initially involves the dual activation of Ca2+/calmodulin-dependent and Ca2+/lipid-dependent protein kinases. In the present study, voltage-clamp conditions that cause substantial increases in intracellular Ca2+ concentration (i.

Motor fluctuations in Parkinson's disease: pathogenetic and therapeutic studies.

The response to continuous intravenous infusion of levodopa was evaluated in 23 patients with Parkinson's disease complicated by motor fluctuations. Conversion from oral to intravenous levodopa treatment resulted in an immediate and sustained stabilization of plasma levodopa levels in both the wearing-off and on-off groups. Motor variability also diminished within the first 24 hours of infusion, although to a much greater extent in patients with the wearing-off phenomenon.

Dopaminergic mechanisms in hemiparkinsonian monkeys.

The motor effects of direct agonists which act selectively on certain dopamine receptors were studied in monkeys rendered hemiparkinsonian by unilateral intracarotid injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The D-2 dopamine agonist, LY 171555, but not the D-1 agonist, SKF 38393, reduced parkinsonian signs and induced rotation away from the side of the nigral lesion. When administered together, SKF 38393 diminished the LY 171555-induced turning in a dose-dependent manner.

Dopaminergic neurons from embryonic mouse mesencephalon are enriched in culture through immunoreaction with monoclonal antibody to neural specific protein 4 and flow cytometry.

Dopaminergic neurons represent a rare neurotransmitter phenotype within the mammalian central nervous system. The mesencephalic dopaminergic neurons form the ascending dopaminergic pathways in mammals and are involved in motor and limbic functions. Here we report that about 30% of all developing mouse mesencephalic cells, including virtually all of the dopaminergic phenotype, express surface membrane determinant(s) recognized by a monoclonal antibody to neural specific protein 4 (NSP4).

Myelin-associated glycoprotein in multiple sclerosis lesions: a quantitative and qualitative analysis.

Myelin-associated glycoprotein (MAG), myelin basic protein (MBP), and proteolipid protein (PLP) were quantitated by immunoassays in nine plaque, inner periplaque, outer periplaque, and normal-appearing white matter regions from brains of five multiple sclerosis patients and compared with the levels found in white matter samples of control subjects matched for age, postmortem time, and brain region. In plaque and inner periplaque regions, all three proteins were substantially reduced due to extensive myelin loss. In outer periplaque regions, MBP and PLP were close to control levels, but MAG was significantly reduced to a mean of 57% of control.

Glycine immunoreactivity localized in the cochlear nucleus and superior olivary complex.

Polyclonal antibodies were made in rabbits against glycine conjugated to bovine serum albumin with glutaraldehyde and were used for immunocytochemical studies in the cochlear nucleus and superior olivary nucleus of the guinea-pig. Antibodies selective for glycine were prepared by affinity chromatography. By dot-blot analysis this preparation showed a strong recognition of glycine conjugates and relatively little recognition of conjugates of most other amino acids tested.

Localization of magnetic interictal discharges in temporal lobe epilepsy.

Three young adults with intractable complex partial seizures were studied by electroencephalography, magnetoencephalography, and electrocorticography. Interictal electroencephalographic (EEG) spikes for each patient were grouped according to their morphological characteristics and distribution across channels. Mapping of simultaneously recorded magnetoencephalographic signals produced dipolar patterns from which the three-dimensional locations of equivalent current dipoles were calculated, whereas the mapping of EEG spikes showed single regions of electronegativity.

Risk factors for ischemic stroke: a prospective study in Rochester, Minnesota.

A cohort of 1,804 residents of Rochester, Minnesota, who were at least 50 years old, free of stroke, and who underwent examination at the Mayo Clinic in 1960, was followed for 13 years. During this period, there were 110 first ischemic strokes and 616 deaths without stroke. The time of onset, if available, or the time of diagnosis of potential risk factors was determined for all patients during the study and was used to construct a proportional hazards model of time to occurrence of stroke with time-dependent risk factors.

Cognitive concomitants of dopamine system stimulation in parkinsonian patients.

Verbal, visuospatial and motor functions were studied in eight Parkinsonian patients both during levodopa stimulated and unstimulated state and in eight matched, untreated, healthy controls. Profound changes in patients' motor status were accompanied by relatively selective effects on delayed verbal memory, a function which was also most impaired compared with controls. With dopaminomimetic therapy, tests of delayed verbal memory consistently improved, but did not reach control performance levels.

Dynamic shape changes of cytoplasmic organelles translocating along microtubules.

Transient shape changes of organelles translocating along microtubules are directly visualized in thinly spread cytoplasmic processes of the marine foraminifer. Allogromia laticollaris, by a combination of high-resolution video-enhanced microscopy and fast-freezing electron microscopy. The interacting side of the organelle flattens upon binding to a microtubule, as if to maximize contact with it.

CRF and cAMP regulation of POMC gene expression in corticotrophic tumor cells.

The effects of corticotropin releasing factor (CRF) on pro-opiomelanocortin (POMC) gene expression were investigated in an anterior pituitary corticotrophic tumor cell line, AtT-20/D16-16. The results of mRNA dot blot hybridization assays suggested that CRF, at a concentration of 10(-7) M, positively regulates the expression of the POMC gene in AtT-20 cells in a concentration-dependent fashion. Evaluation of the time course of this effect indicated that CRF had a biphasic mode of action.

Cortical glucose utilization patterns in primary degenerative dementias of the anterior and posterior type.

Regional cortical function was evaluated in 13 patients with primary degenerative dementia and six age-matched, neurologically normal control individuals. Five patients were selected on the basis of preponderant signs of posterior dementia, five had mainly signs of anterior dementia, and the remaining three evidenced mixed anterior-posterior cognitive deficits. Positron emission tomographic scans following the intravenous administration of fluorodeoxyglucose revealed a characteristic pattern of abnormalities in each group: those with posterior dementia, as primarily manifested by verbal and visuospatial deficits, had a predominant focus of hypofunction in the posterior parietal and temporal regions; those with the less common anterior dementia, evidenced by prominent personality and social behavioral changes, had their most conspicuous abnormality in the anterior frontal cortex; those with approximately equal signs of anterior and posterior dementia had abnormalities in both anterior frontal and posterior parietal-temporal areas.

Studies of the pathogenesis of Gaucher's disease: tissue distribution and biliary excretion of [14C]L-glucosylceramide in rats.

The time course of the clearance from the blood and the tissue localization of [14C]L-glucosylceramide, a nonmetabolizable enantiomorph of D-glucosylceramide that accumulates in Gaucher's disease, has been determined. 14C-labeled L-glucosylceramide injected intravenously in the form of micelles or liposomes is rapidly removed from the circulation. Most of this lipid is taken up by the liver where it is found in both hepatocytes and nonparenchymal cells.

Exercise and the antiparkinsonian response to levodopa.

The contribution of acute physical exercise to the motor fluctuations occurring in advanced Parkinson's disease was studied in four patients using a standard treadmill protocol. With a constant optimal-dose intravenous levodopa infusion, no changes in plasma drug levels or antiparkinsonian response were observed during or for 60 min following a 35-min exercise period, during which the work load increased from minimal to vigorous. Although an effect of exercise on levodopa absorption from the gastrointestinal tract cannot be excluded, there seems to be no basis on which to implicate acute physical activity, at levels ordinarily experienced by parkinsonian patients, in the pathogenesis of the fluctuations in motor performance.

Environmental risk factors for Parkinson's disease: the epidemiologic evidence.

Descriptive data from several studies suggest variations in the frequency of Parkinson's disease in different population groups. Door-to-door surveys were carried out among a biracial U.S.

Dissociation between corticotrophin and catecholamine responses to isoprenaline in humans.

1. The pituitary-adrenocortical, sympathoadrenomedullary and renin-angiotensin-aldosterone systems contribute to circulatory and metabolic homeostasis during stress. One possible site of co-ordination of these systems is the beta-adrenoceptor.

Regulation of the pentose phosphate pathway in human astrocytes and gliomas.

Several aspects of the regulation of the pentose phosphate pathway were examined in cultured normal human cortical astrocytes and gliomas of pathological grades I-IV. The generation of radiolabeled CO2 from [1-14C]glucose by the oxidative arm of the pentose phosphate pathway is a saturable process and has a maximum flux rate of 8-9 nmol/hr/mg cell protein. The flux can be blocked by the glycolytic inhibitor iodoacetamide but is unaffected by agents which inhibit oxidative phosphorylation.