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Biomedical subjects

A Kuruvilla

Publications and source records attributed to A Kuruvilla.

At least 73 records · Page 4Linked to original sources
PubMed1992

Topographic analysis of visual evoked potentials from flash and pattern reversal stimuli: evidence for "travelling waves".

In this mapping study of the entire scalp area, the responses to flash (FL) and pattern reversal (PR) stimuli were studied in 34 normal subjects. The N70, P100, N135 and P180 were similar from both stimuli but with some differences in amplitude and latency, especially the variability of the latency of P100 from FL. A polarity inversion was usually seen for all components, especially at opposite ends of the scalp and a zero-potential was noted for all four components near Cz Pz. Evidence is seen that the frontal N100 is likely not the other end of a dipole involving the posterior P100. Lateral components as P120, N150 and N200 were also described. The major finding was evidence of "travelling" waves that appear to move in both the AP and PA directions throughout the scalp that eventually arrive on the posterior regions and appear as N70, P100, N135 and P180.

Adolescent↗
PubMed1992

A study of serum prolactin levels in schizophrenia: comparison of males and females.

1. Serum prolactin levels were measured in large cohorts of schizophrenic patients (67 males and 42 females) and normal subjects (78 males and 42 females). 2. There was no significant differences between the serum prolactin levels of patients and controls, except in the age group 15-29 years. There were no significant differences between the serum prolactin levels of males and females, either among the patients or the control subjects. 3. The rise in serum prolactin levels after the commencement of neuroleptic medication in the patients was greater in females than in males even though the female patients received neuroleptics at lower doses. 4. These data indicate that serum prolactin levels in unmedicated males and females are similar; however, the prolactin response to neuroleptic medication is greater in females than in males.

Adolescent↗
PubMed1992

Otogenic brain abscess: the Syracuse experience.

A review is presented of five cases of otogenic brain abscesses (from among 34 cases of brain abscesses of all causes) treated during a 16-year period at a major university hospital in upstate New York. Although the morbidity and mortality rates are high for patients with brain abscess, advances in the microbial isolation methods, specificity of antimicrobial agents, and earlier diagnosis by CT scans have all contributed to an improved outcome for this dreaded disease.

Adult↗
PubMed1992

Evaluation of drug effects on spinal cord injury--an experimental study in monkeys.

Contusion injury is produced experimentally in anaesthetised monkeys by weight drop method. A group of animals having laminectomy alone served as sham controls. Drugs were administered 30 min after injury initially. Naloxone and nifedipine were administered as single dose administration immediately after injury. Dipyridamole and DMSO were administered daily for a period of 1 week. Acetylcholinesterase (AchE) was estimated in 2 spinal tissue segments, S1-at the site of injury and S2-the segment above the site of injury, at the end of 1 week after sacrificing the animals. Contusion injury produced significant decrease in specific activity of AchE in the traumatised segment of the experimental animals. The non-traumatised adjacent segment did not show any significant change. Nifedipine, naloxone and DMSO produced a decrease in AchE activity in S1 and S2 segments. Monkeys developed paraplegia after contusion injury. A score 2+ was observed after 1 week as compared to the score of 4+ of sham controls. Single dose administration of naloxone seemed to reverse the motor deficit by getting a score of 3+; other drugs did not produce any beneficial effect on motor deficit.

Animals↗
PubMed1992

Coexistent oral cryptococcosis and Kaposi's sarcoma in acquired immunodeficiency syndrome.

As experience with the acquired immunodeficiency syndrome has grown during the last decade, it has become important to recognize interactions between the opportunistic infections and malignancies that complicate the course of patients with acquired immunodeficiency syndrome. Our recent experience as described in this paper reveals that Kaposi's sarcoma and cryptococcal infection can associate in such a manner. The first reported case of oral Cryptococcus neoformans infection within a Kaposi's sarcoma lesion in a patient with acquired immunodeficiency syndrome is described. Based on the clinical course of this patient, it is an important consideration that the sarcoma may have harbored and even protected the fungus during systemic amphotericin B therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1991

High-level expression of functional platelet-activating factor receptors on a human B lymphoblastoid cell line.

Binding of platelet-activating factor (PAF) was characterized in a human b lymphoblastoid cell line, ASK.0. [3H]PAF binding to these cells was time-dependent, reaching equilibrium at 60 minutes, and saturable. Scatchard analyses of saturation binding experiments revealed a single class of PAF binding sites (108,000 +/- 17,000 per cell) with a KD of 2.16 +/- 0.41 nM. That the binding sites were specific for PAF was demonstrated by competition studies. PAF was shown to increase the intracellular calcium concentrations of ASK.0 cells in a dose-dependent manner with an EC50 of 7 nM. We have, therefore, identified a B cell line expressing large numbers of functional PAF receptors.

B-Lymphocytes↗
PubMed1991

Platelet-activating factor induces phospholipid turnover, calcium flux, arachidonic acid liberation, eicosanoid generation, and oncogene expression in a human B cell line.

Platelet-activating factor is a potent mediator of the inflammatory response. Studies of the actions of platelet-activating factor have centered mainly around neutrophils, monocytes, and platelets. In this report we begin to uncover the influence of platelet-activating factor on B lymphocytes. Employing the EBV-transformed human B cell line SKW6.4, we demonstrate that platelet-activating factor significantly alters membrane phospholipid metabolism indicated by the incorporation of 32P into phosphatidylcholine, phosphatidylinositol, and phosphatidic acid but not significantly into phosphatidylethanolamine at concentrations ranging from 10(-9) to 10(-6) M. The inactive precursor, lyso-platelet-activating factor, at a concentration as high as 10(-7) M had no effect on any of the membrane phospholipids. We also show that platelet-activating factor from 10(-12) to 10(-6) M induced rapid and significant elevation in intracellular calcium levels, whereas lyso-platelet-activating factor was again ineffective. We further demonstrate the impact of platelet-activating factor binding to B cells by measuring platelet-activating factor induced arachidonic acid release and 5-hydroxyeicosatetraenoic acid production. Moreover, platelet-activating factor was capable of inducing transcription of the nuclear proto-oncogenes c-fos and c-jun. Finally we explored the possible role of 5-hydroxyeicosatetraenoic acid as a regulator of arachidonic acid liberation demonstrating that endogenous 5-lipoxygenase activity modulates platelet-activating factor induced arachidonic acid release perhaps acting at the level of phospholipase A2. In summary, platelet-activating factor is shown here to have a direct and profound effect on a pure B cell line.

Arachidonic Acid↗
PubMed1991

Quantitative measurements of capillary transport in human brain tumors by computed tomography.

The rate at which water-soluble chemotherapeutic drugs enter brain tumors can be extremely variable. The ability to measure or predict the rate of drug entry may have an important role in treatment. We have developed a method that uses information from contrast-enhanced computed tomographic scans to measure quantitatively the rate of transcapillary transport of iodinated compounds in brain tumors. In a group of 10 patients with brain tumors, we obtained serial measurements of tissue (Am) and arterial plasma (Cp) iodine concentration from timed computed tomographic scans done over 30 minutes, after intravenous infusion of meglumine iothalamate (Conray-60). These measurements were analyzed with a two-compartment pharmacokinetic model and nonlinear least-squares regression methods to obtain K1, a blood-to-tissue transfer constant; k2, a tissue-to-blood rate constant; and Vp, tissue plasma vascular volume. Images of K1, k2, and Vp were reconstructed after calculating these values for each 0.8 x 0.8 x 5-mm volume element of the original data. Mean whole tumor K1 values varied from 2.0 mu 1 gm-1 min-1 in a thalamic astrocytoma to 33.9 mu 1 gm-1 min-1 in a glioblastoma multiforme. The value of k2 varied from 0.034 to 0.108 min-1, and Vp varied from 2.4 to 7.9 ml 100 gm-1. In tumor-free brain, the K1 of meglumine iothalamate was 2.9 mu 1 gm-1 min-1; k2 was 0.058 min-1; and Vp was 2.1 ml 100 gm-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Leiomyosarcoma of the sinonasal tract. A clinicopathologic study of nine cases.

The clinicopathologic features of nine cases of sinonasal tract leiomyosarcoma (SNTL) referred to the Armed Forces Institute of Pathology, Washington, DC, during the period from 1970 through 1988 are described. This report represents the largest study to date on SNTL, and our results are compared with the 21 previously reported cases of SNTL. Of the nine cases described, patients ranged in age from 22 to 86 years (mean, 55 years). The most frequent clinical presentation was nasal obstruction unilaterally. The neoplasms were limited solely to the nasal cavity in four cases (44%) and involved both the nasal cavity and paranasal sinuses in the remaining five cases. Light microscopic, immunocytochemical, and ultrastructural features served to characterize these tumors as malignant neoplasms of smooth-muscle origin. In contrast with previous studies, immunocytochemistry was employed to differentiate SNTL from other spindle cell malignancies of the region, using newly available monoclonal antibodies to smooth-muscle antigens. Treatment was surgical. Radiotherapy or chemotherapy did not appear to affect the progression of the disease. Furthermore, no relationship was found between the aggressiveness of SNTL and morphologic parameters (eg, mitotic count and tumor size). Instead, prognosis was dependent on the distribution of disease at presentation. Of all 30 patients with SNTL described to date, 10 had the neoplasm confined solely to the nasal cavity. The 10 neoplasms did not recur. We conclude that SNTL may best be regarded as a locally aggressive neoplasm with only limited metastatic potential and that it could be curable by complete surgical excision.

Adult↗
PubMed1990

Pathologic manifestations of acquired immunodeficiency syndrome in the head and neck.

Various diseases of the head and neck that appear in association with AIDS have been delineated. These diseases may be the initial manifestations of AIDS or may be part of systemic involvement following HIV infection. Both clinicians and pathologists must be aware of the protean manifestations of AIDS in order to establish an accurate and complete diagnosis. Once the diagnosis is established, therapy, which may potentially enhance the quality of life of the infected individual, can be initiated.

AIDS-Related Complex↗
PubMed1989

Regeneration of the eighth cranial nerve. III. Central projections of the primary afferent fibers from individual vestibular receptors in the bullfrog.

The projection site in the central nervous system of individual end-organ branches of regenerated vestibular nerves was documented in bullfrogs. The eighth cranial nerve was surgically sectioned in 12 bullfrogs (Rana catesbeiana) and allowed to regenerate. Horseradish peroxidase was used to label the primary vestibular afferent fibers from the whole nerve (one frog) and the whole anterior branch (two frogs), and the individual receptor end-organ branches to the anterior semicircular canal (three frogs), the horizontal semicircular canal (three frogs), and the sacculus (three frogs). A sufficient number of fibers from the individual receptors were labeled in nine specimens to allow a description of their central projection pattern. The overall pattern of central projections of the regenerated nerves was similar to the pattern of normal nerves. In the eighth nerve root proper and in the area proximal to the vestibular nuclei, fibers from the anterior semicircular canal were ventral, fibers from the sacculus and posterior branch were dorsal, and fibers from the horizontal semicircular canal were in an intermediate position. In ventral, superior, and descending vestibular nuclei, a projection pattern was also identifiable in some specimens. The fibers of the anterior semicircular canal projected ventral to the fibers of the horizontal semicircular canal, with fibers from the posterior branch more dorsal. The saccular fibers projected to the dorsal aspect of the ventral nucleus and the ventral aspect of the dorsal nucleus. For the most part, projections in the regenerated specimens, as verified histologically, were comparable to individual end-organ projections previously identified in normal frogs. The only major discrepancy between the findings from the regenerated specimens and those from normal frogs was in the position of the vestibular tract and the innervation to the medial nucleus. The regenerated vestibular tract was shifted laterally in the brain stem. Regenerated thick and thin fibers were intermixed in the tract and projected to the medial nucleus. Normally, the thin fibers are lateral to the thick fibers in the tract. Therefore, the regenerated afferent fibers of the vestibular nerve selectively reinnervated the vestibular nuclei, and the fibers to the individual end-organs selectively reinnervated particular parts of the nuclei. In addition, the thick and thin regenerated fibers preserved the type of bouton endings normally found. The regenerated thick fibers had rare boutons en passant and a great number of collaterals, while the thin fibers had numerous boutons en passant and only a few collaterals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Changes in noradrenaline and histamine in monkey spinal cords traumatised by weight drop, compression and subsequent decompression.

Levels of noradrenaline (NA) and histamine (H) in the spinal cord of monkeys at 8, 24 and 48 hr following 200 g/cm contusion injury, 50 g of compression injury at 8 hr and decompression for 16 and 40 hr following 8 hr of compression were studied in the traumatised and in an adjacent non-traumatised segment. The NA level doubled in the traumatised and non-traumatised segments at 8 hr contusion injury followed by a slow decline to control values at 24 and 48 hr of contusion injury. There was no change in NA content of the spinal cord segments at 8 hr of compression injury. Decompression for 16 hr following 8 hr of compression increased NA content of the traumatised segment. H levels decreased in the traumatised and non-traumatised segments at 24 and 48 hr of contusion injury. Compression for 8 hr elevated H in the traumatised and non-traumatised segments. On decompression H level was further increased in the traumatised segment.

Animals↗
PubMed1987

Changes in the content of dopamine and its metabolites in the basal ganglia following right middle cerebral artery occlusion and reflow in monkeys.

Focal ischaemia was produced experimentally in Macaca radiata monkeys by occlusion of middle cerebral artery (MCA). There was a lowering of the dopamine (DA) content of basal ganglia after 4 and 12 h of occlusion. DA content was restored to normal in basal ganglia after restoration of blood flow. With the progress of time the DA content was increased above that of sham controls. Changes were also observed in the non-occluded left basal ganglia. The homovanillic acid (HVA) content was decreased significantly at 12 h after occlusion. After the onset of reflow, the HVA content of the right basal ganglia was higher than that of sham controls. The 3,4 dihydroxyphenylacetic acid (DOPAC) content of right basal ganglia was significantly decreased after 12 h occlusion. Reflow restored the level of DOPAC to normal within 1 h after removal of clip. Discrete changes were also observed in the left basal ganglia at some of the time intervals.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Morphological aspects of the vestibular nerve of the squirrel monkey.

A morphological study of the vestibular nerve of a primate, the squirrel monkey, revealed a systematic organization of neurons according to fiber diameter. At the center of the cristae, thick fibers align in two parallel rows along the long axis; in the periphery of the cristae, thin fibers predominate. Within the superior vestibular nerve the thick fibers of the anterior and horizontal semicircular canals and utricle are situated in the anterosuperior area, the thin fibers in the posterior part. A similar segregation occurs with fibers of the posterior ampullary nerve and the saccule within the inferior vestibular nerve. The fibers continue to segregate at the root entry zone where they lose their Schwann's cell ensheathing and begin to divide into secondary central branches. There is a correspondence between the volume of the ganglion cell and the fiber diameter; hence, a segregation of ganglion cells according to their size also takes place in the vestibular nerve. The organization of the primate's vestibular nerve is similar to that found earlier in an anuran. The relevance of the phylogenetic preservation of the vestibular nerve's anatomical organization is discussed in terms of current physiological findings, which support the differential role of fibers of different diameters in vestibular function.

Animals↗