Biomedical subjects
Publications and source records attributed to A Prasad.
Three cases of solitary osteochondroma of the spine are reported. Two presented with cervical myelopathy and one with radiculopathy. Plain radiography or tomography is adequate for the diagnosis in the majority of cases; nevertheless, a CT scan or MRI is of immense help in planning surgical treatment. The radiological features of spinal exostoses are reviewed.
Explore the source record for details and available documents.
Primary cultures of cerebral cortical neurons were prepared from 7- to 8-day-old chick embryos. The effect of ethanol on GABA-activated membrane current was examined using whole-cell voltage-clamp recording in cells maintained for 3-25 days in vitro. In approximately 60% of neurons examined ethanol caused a potentiation of the membrane current elicited by GABA. The threshold concentration of ethanol was 1 mM, and the potentiating effect of ethanol on GABA-activated currents was maximal at 10 mM. In many cells higher concentration (40-50 mM) of ethanol inhibited GABA-activated currents. These effects of ethanol were all reversible.
Modern neuronanatomical techniques were used to investigate the development of the avian sympathetic preganglionic cell column in the spinal cord of the chick embryo. [3H]thymidine autoradiography indicated that the majority of these preganglionic, or "Terni column" neurons are generated between stages 18 and 24 (days 2-4). This coincides with the genesis of the somatic motoneurons in the thoracic levels of the cord, and therefore differences in the time of origin cannot explain the divergent fates of these two neuronal populations. Data obtained from short-survival autoradiographic experiments indicated that many early born cells remain close to the ventral region of the ventricular epithelium until day 5 of incubation. Ventral root injections used to label retrogradely neurons projecting an axon into the ventral root (Terni cells and somatic motoneurons) have labeled neurons next to the ventricular epithelium at the same early stages. Thus, it seems likely that some Terni cells, if not all, maintain medial positions and do not migrate laterally to join a common motor column before initiating a dorsal migration. Analysis of a closely staged series of embryos, whose Terni column neurons were retrogradely labeled with wheat germ agglutinin-horseradish peroxidase (WGA-HRP), revealed that between days 5 and 8 of incubation, Terni column neurons migrated dorsally to attain their adult position adjacent to the central canal. These changes in position were reflected in the changing morphology of the Terni column neurons, visualized by the Golgi-like HRP labeling. The positions of the migrating Terni cells differed from those of commissural cells, indicating that these fibers are not the substrate for the dorsal migration. The dorsal migration of Terni column cells was not disrupted by the surgical removal of the sympathetic ganglia, the synaptic targets of these neurons, nor by disruption of spinal afferents. Taken together, these results suggest that the migratory behavior of Terni cells in distinctive when compared to that of somatic motoneurons, and that local and/or intrinsic cues within the spinal cord guide the dorsal migration of Terni column cells.
Calcification in cases of medulloblastoma has been described with varying frequency (10%-15.4%) on computed tomographic (CT) scan. Usually these calcifications are small in size and speckled. The authors report a case of medulloblastoma with extensive calcification in the lateral hemisphere of the cerebellum in an 18-year-old boy.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Sensory ataxia as the chief manifestation of acute neuropathy is rather rare. Of the 224 cases of acute polyneuropathy seen over 6 years (1984-1990) only 10 patients (M:F 3:7) had disabling ataxia as the presenting feature. Their ages ranged from 14-61 years. Antecedent febrile illness was present in 6 patients and the peak deficit evolved over 2-25 days. Severe ataxia, paresthesia, distal areflexia and predominant joint sense loss were common to all, motor weakness was either absent or insignificant. CSF was acellular and revealed elevated protein in 3 subjects. All patients had electrophysiological evidence of severe sensory neuropathy with mild or no motor neuropathy. Sural nerve biopsy in one patient showed loss of large, as well as small, diameter myelinated fibres, secondary demyelination, but no evidence of inflammation. At follow up marginal to moderate improvement in ataxia was noted in only 5 patients. Absence of ophthalmoplegia and motor weakness, poor prognosis and characteristic electrophysiological and histopathological observations suggest that acute ataxic neuropathy may be a distinct entity.
A case of lymphocytic hypophysitis (LYHY) in a menopausal woman is presented. A review of the literature suggests that conservative treatment may be tried in suspected cases of LYHY, if the vision of the patient is not threatened. A transphenoidal stereotactic biopsy of the mass may be performed if the patient fails to improve or deteriorates, thus avoiding open exploration of the sella in selected cases.
Two cases of gross post-operative cerebrospinal fluid (CSF) leakage along an indwelling ventricular catheter are reported. The CSF appeared to leak through the perforations of the ventricular catheter, as well as at the site of penetration of the ventricular wall. A small or slit ventricle with high intraventricular pressure may thus be a predisposing factor for this localized CSF collection.
The activities of cysteine proteinases which include several lysosomal cathepsins are controlled by naturally occurring inhibitory proteins termed cystatins. Cystatins occur both intracellularly and extracellularly in various tissue fluids including tears. Tears were collected by the Schirmer paper strip method from healthy volunteers who had no history or signs of external ocular disease. The tear components were extracted from the filter papers, and used to determine the apparent free cystatin activity and cystatin levels of tears, and for immunoblots. Tears were also collected using capillary tubes for the measurements of cystatins. By titrating papain, a cysteine proteinase, of known specific activity with tear fluid, relatively high levels of apparent free cystatin activity were demonstrated in tears: 28.8 +/- 3.47 (S.E.M.) pmols papain inhibited per mg tear protein (n = 9). The concentrations of cystatins in tear samples were measured by an indirect enzyme-linked immunosorbent assay (ELISA) using antibodies against human salivary cystatin S and purified cystatin S as standard. The ELISAS revealed that tears contain high levels of cystatin-like immunoreactive material, amounting to about 10% of tear proteins. In microgram cystatin S/mg protein the values were: right eye: 94.7 +/- 9.9; left eye: 115.5 +/- 14.8; n = 12. Cystatin levels of tears collected using capillary tubes were comparable: 120.7 +/- 19 micrograms/mg protein (n = 10). Immunoblots of tear fluids revealed a protein of about 14,000 molecular weight which reacted with antihuman cystatin SN monoclonal antibodies. Protein(s) of similar molecular weight were visualized using antibodies against human cystatins S and C. Less abundant additional cystatin-like immuno-reactive proteins were detected by using the two latter antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)
The authors reported an increased in the cerebrospinal fluid concentration of glutamine in seven paranoid schizophrenic patients. They found no changes in the levels of the remaining 20 free amino acids assayed.
Explore the source record for details and available documents.
It has been difficult to document the subjective complaint of glare. Devices to quantify this problem include the Miller-Nadler glare tester (MNGT) and the brightness acuity tester (BAT). We used these devices to evaluate a group of pseudophakic subjects (15 eyes with posterior-chamber intraocular lenses) and a group of normal subjects (32 low myopic eyes). A subject's ability to discern contrast with a background glare source is measured as a percentage with the MNGT. The number of lines lost on the Snellen chart as a light is brightened progressively over the line of vision is the BAT score. A Wilcoxon signed-ranks test showed no significant change without correction (SC) to with correction (CC) with the BAT but was significant at P less than .001 with the MNGT. The BAT scores for the normal group CC (mean, 0.59) compared with the intraocular lens group CC (mean, 3.0) with the Mann-Whitney U test showed a statistically significant difference (P less than .001). There also was a difference with the MNGT between normal group CC (mean, 5.1%) and pseudophakic group CC (mean, 8.9%) at P less than .001). These results suggest that pseudophakic subjects have marked visual dysfunction secondary to glare. The BAT, however, showed a more easily quantifiable change unaffected by spectacle correction.
Explore the source record for details and available documents.
A significantly higher proportion of patients with headache showed scores in the psychopathological range of the General Health Questionnaire (GHQ) compared with controls, with ratings particularly high on the anxiety and depression subscales. Across the whole group, there was a significant negative correlation between platelet monoamine oxidase (MAO) activity and GHQ score overall, and with the anxiety and depression subscales. There was a significant positive correlation between platelet MAO activity and urinary output of the endogenous MAO inhibitor, tribulin. Within the migraine group, there was a significant negative correlation between tribulin output and GHQ score. These findings suggest that the biochemical nature of the anxiety associated with migraine may differ from that in other conditions such as generalized anxiety disorder where high platelet MAO activity and high tribulin output have been reported.
Explore the source record for details and available documents.
Feldspatic porcelains are usually material in cosmetic dentistry, but they cannot be used without a reinforcement system. Aluminous or metallic frames produce a strong internal specular reflexion, which destroys the deep natural appearance of teeth. Inspired from glass ceramic industry, the concept of strengthening in Optec hsp is induced by a high level of micro-crystalline dispersion, spread in the material. Micro-crystals increase strength by division of stresses and improve the scattering of light as we observe in the natural tooth. The laboratory method is based on routine technics of porcelain building. No special equipment, or high temperature are necessary for producing, laminate veneers, inlays, onlays, crowns, and tree units anterior bridges.