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Biomedical subjects

S Ganesan

Publications and source records attributed to S Ganesan.

At least 37 records · Page 2Linked to original sources
PubMed1998

Invasive laryngeal candidiasis: a cause of stridor in the previously irradiated patient.

Upper airway obstruction is always a serious condition. In patients who have previously been irradiated for a laryngeal malignancy, it normally implies either residual or recurrent disease. We report a case of stridor due to invasive laryngeal candidiasis in a patient who had undergone radiotherapy for a T1a N0 squamous cell carcinoma of the glottis eight months earlier. Extensive investigation failed to identify recurrence of disease and the patient responded to prolonged topical antifungal therapy. Infection with Candida species is most frequently found in debilitated or immunocompromised patients. Although cases of upper airway obstruction in children secondary to idiopathic laryngeal candidiasis have been reported, to our knowledge no such presentation has been described in adults. This report highlights the difficulty of diagnosis and treatment. Familiarity with candidal infection is important for early diagnosis and appropriate treatment.

Administration, Topical↗
PubMed1998

Characterization of native fluorescence from DMBA-treated hamster cheek pouch buccal mucosa for measuring tissue transformation.

The steady-state native fluorescence spectra of extracts of normal mucosa as well as of different stages of oral lesion of the 7,12-dimethylbenz (a) anthracene (DMBA)-induced hamster cheek pouch carcinogenesis model have been measured and analysed at 405 nm excitation. The emission spectra were scanned from 430 to 700 nm to characterize the native fluorescence of endogenous porphyrin and other fluorophores under various tissue transformation conditions, such as hyperplasia, papilloma, early invasive carcinoma and well-differentiated squamous cell carcinoma. Two ratio parameters, R1 = (I530/I620) and R2 = (I530/I630), are introduced to quantify the diagnostic potentiality. The ratio values were found to decrease as the stage of the cancer increases. The suggested critical values for both R1 and R2 for normal mucosa is above three, and the suggested critical value for tissues with lesion is less than three. It was also found that the values for R1 and R2 for well-differentiated squamous cell carcinoma is less than one. The ratio parameter R2 is selected for discrimination between normal mucosa and oral lesions, as the difference in the R2 value between normal and DMBA-treated tissue is higher than that for R1.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

Native fluorescence spectroscopy of normal and malignant epithelial cells.

Native fluorescence spectroscopy of normal human oral and malignant epithelial cells was studied under uv excitation. Differences were observed in the excitation spectra between normal and malignant epithelial cells for 340 nm emission. The observed differences may be utilized for both discrimination and changes associated with the amino acid residues in the cellular proteins.

Carcinoma, Squamous Cell↗
PubMed1997

Generation and detection of lung stress waves from the chest surface.

In anesthetized pigs, we generated stress' waves by imposing a distortion on the intercostal muscle between the 5th and 6th ribs. Stress waves were detected by two accelerometers, 5-7 cm apart, oriented in either the ventral-dorsal or cranial-caudal direction. Cross-spectral analysis was used to calculate transit time. Waves of velocities similar to those of lung shear waves were detected at transpulmonary pressures (Ptp) above 15 cmH2O in the nonedematous lung and above 25 cmH2O Ptp in the edematous lung. Waves were detected in the frequency range 9-40 Hz. Stress wave velocity increased from 287 +/- 24 (SD) cm/sec at 18 cmH2O Ptp to 342 +/- 41 cm/sec at 26 cmH2O Ptp, consistent with shear waves propagating in the lung having a shear modulus of 0.9 Ptp and lung density of 0.20 g/cm3. Stress wave velocities at 25 cmH2O Ptp decreased with the increases in lung density induced by alveolar edema, consistent with elasticity theory. An elasticity analysis showed the existence of lung-rib cage interfacial waves with properties similar to the measured stress waves.

Anesthesia↗
PubMed1997

Horner's syndrome: a rare presentation of cervical sympathetic chain schwannoma.

We describe a cervical sympathetic chain schwannoma in a 77-year-old woman who presented with a neck mass and Horner's syndrome. Such schwannomas are rare and this is the first documented case of a Horner's syndrome at presentation. The mass was excised via a cervical approach and her post-operative course was uneventful. The prognosis is excellent, with recurrence being rare. A brief discussion of the pathology, presentation, diagnosis, and treatment of this condition is made in this paper. The relevance of the uncertainty in diagnosis is discussed with the message that a pre-operative Horner's syndrome may guide the surgeon in the care of the patient but we suggest that in all cases proper counselling of the possible neurological consequences of this surgery be conducted.

Aged↗
PubMed1997

Expression of depressed mood: a comparative study among Japanese and Canadian aged people.

OBJECTIVE: To investigate differences of expression regarding depressed mood between Japanese and Canadian aged people. METHOD: The Zung Self-Rating Depression Scale (SDS) was applied to people aged 65 and over in Ohira, Japan, and Steveston, British Columbia, Canada. RESULTS: The number of subjects who filled out the SDS completely was 2180 for the Japanese sample and 183 for the Canadian sample. The mean SDS indexes of the Japanese and the Canadian samples were 44.03 and 44.34, respectively. The Canadian sample showed a higher average score in 11 items out of 20, whereas the Japanese sample showed a higher score on only 4 items. The factor analysis of those samples showed only small differences. CONCLUSIONS: The Canadian sample showed a higher average score in more items compared with the Japanese sample. This indicates that Canadian aged people express their depressed moods more clearly and spontaneously than Japanese aged people.

Activities of Daily Living↗
PubMed1996

Lipoma of the parotid gland presenting with facial palsy.

Facial palsy in the presence of ipsilateral parotid tumour is considered to be pathognomonic of malignancy. However, benign neoplasms and inflammatory lesions of the parotid gland have been reported to present with facial palsy. A case of lipoma of the parotid gland associated with partial facial paralysis is reported. Lipomas are very rarely seen in this site. To our knowledge, a lipoma of the parotid producing facial paralysis has not been described previously. This report highlights the difficulties in pre-operative diagnosis and management of such a lesion.

Facial Paralysis↗
PubMed1996

A centralized system for monitoring clozapine use in British Columbia.

The Clozapine Resource Centre in British Columbia is a centralized information source for all physicians wishing to prescribe clozapine and also performs back-up hematological and compliance monitoring. Laboratories fax weekly hematology results to physicians and to the center. The center enters results in a national database and compiles twice-weekly noncompliance reports; physicians are notified of abnormal results, and caregivers of noncompliance. The centralized system obviates the practice in some jurisdictions of hiring case coordinators to oversee these procedures and may reduce physician reluctance to prescribe clozapine. It improves coordination among monitoring and treatment parties and ensures better continuity of care.

Adverse Drug Reaction Reporting Systems↗
PubMed1995

A finite element analysis of the effects of the abdomen on regional lung expansion.

A finite element model of the dog lung, heart and abdomen, consisting of three solid linearly elastic bodies, was developed to study the effects of gravity on the vertical stress distribution and lung volume in different body positions at functional residual capacity (FRC). The geometry of the lung was obtained from an isolated dried dog lung after inflation to total lung capacity (TLC). The compliance of the rib cage, diaphragm and the abdomen was simulated by spring elements located on their surfaces. In the prone position, gravitational forces acting only on the lung contributed to the vertical gradient (0.19 cmH2O/cm) in transpulmonary pressure (Ptp). This result was independent of chest wall compliance. In the supine position, the addition of the heart and abdomen with a compliant diaphragm and abdominal walls increased the vertical Ptp gradient to 0.53 cmH2O/cm. In the head-up (upright) position, both heart and abdominal weight contributed to the vertical gradient (0.47 cmH2O/cm). Diaphragmatic compliance was of less importance to the vertical gradient in the head-up and head-down positions in the absence of the abdomen. The smallest vertical gradient (0.11 cmH2O/cm) was obtained in the head-down position with abdominal weight reducing the gradient caused by lung weight. Lung volume at FRC was virtually unaffected by gravity in the prone body position, was reduced by gravity in the supine and head-down positions but increased in the head-up position. The effects of a compliant diaphragm and abdominal weight are important contributors to the distribution of stress and volume in the intact lung.

Abdomen↗
PubMed1995

Spectroscopic studies on the interaction of three partially hydrogenated acridine dyes with calf thymus DNA and their structural comparison.

The interaction of three partially hydrogenated acridine dyes (acridine I, acridine II and acridine III) with calf thymus DNA was studied using spectrophotometric and spectrofluorometric methods. This paper presents the evidence for the formation of complexes between acridine I, II and III with calf thymus DNA. From the results of this studies various binding parameters were evaluated. The binding constant for acridine I and acridine III ranged from 2.1 to 4.4 x 10(5) M-1 for the P/D ratio from 4.29 to 0.56 while for acridine II this constant increased from 0.78 to 2.26 x 10(5) M-1 for the P/D ratio 12 to 2.38 and decreased to 1.47 at P/D ratio 1.34. The Scatchard analysis indicated a cooperative binding of acridine II to calf thymus DNA as compared to acridine I and III. A red shift in the visible absorption bands for dye DNA complexes (for acridine I = 8, acridine II = 7, and acridine III = 9 nm) suggested an electronically coupled interaction mode for the dyes. It is concluded that acridine II interacted stronger with calf thymus DNA than acridine I or III. The results are interpreted in terms of their crystal structures and also with the already reported DNA binder structures.

Acridines↗
PubMed1995

A clinical study of clozapine treatment and predictors of response in a Canadian sample.

OBJECTIVE: To study the clinical response to clozapine in patients with refractory schizophrenia. METHOD: Open trial of clozapine in 61 consecutively-treated patients. RESULTS: Following clozapine, the level of function of patients was improved relative to admission (p = 0.0001) and to the highest level in the previous year (p = 0.0001). Severity of illness was decreased (p = 0.0001). Overall, 31% of the patients were classified as responders to clozapine and the responders were all identified by 32 weeks of treatment. Poor functioning in the previous year was associated with less favourable response. At a mean interval of 26 months following discharge, 72% of the patients were continuing clozapine treatment. CONCLUSIONS: This open trial of patients who were treated consecutively indicates a comparable degree of response to clozapine as observed in controlled clinical trials, and that level of functioning in the previous year was the best predictor of response.

Adolescent↗
PubMed1993

Strand-specific binding to duplex DNA ends by the subunits of the Escherichia coli RecBCD enzyme.

RecBCD enzyme of Escherichia coli unwinds DNA from duplex DNA ends to produce single-stranded DNA, a central intermediate in the major (RecBCD) pathway of homologous recombination. To help elucidate the mechanism of unwinding we studied the complex of RecBCD enzyme bound to duplex DNA ends in the absence of ATP, a cofactor required for unwinding. In this complex the terminal 16 or 17 nucleotides of the 3' terminated strand and the terminal 20 or 21 nucleotides of the 5' terminated strand were protected from DNase I cleavage. u.v.-irradiation of the complex cross-linked the RecB subunit to the 3' terminated strand and the RecC and RecD subunits of the 5' terminated strand. Studies using pyridoxal 5-phosphate, an inhibitor of the RecBCD enzyme, corroborated the cross-linking studies and revealed a conformational change in the enzyme upon binding to DNA. Based on these results and proposals by others, we present a model for the mechanism of DNA unwinding by RecBCD enzyme.

Base Sequence↗
PubMed1993

A genetic analysis of various functions of the TyrR protein of Escherichia coli.

The TyrR protein is involved in both repression and activation of the genes of the TyrR regulon. Correction of an error in a previously published sequence has revealed a Cro-like helix-turn-helix DNA-binding domain near the carboxyl terminus. Site-directed mutagenesis in this region has generated a number of mutants that can no longer repress or activate. Deletions of amino acid residues 5 to 42 produced a protein that could repress but not activate. The central domain of TyrR contains an ATP-binding site and is homologous with the NtrC family of activator proteins. A mutation to site A of the ATP-binding site and other mutations in this region affect tyrosine-mediated repression but do not prevent activation or phenylalanine-mediated repression of aroG.

Amino Acid Sequence↗
PubMed1993

Alveolar liquid pressure measured in the intact rabbit chest by micropuncture.

Previous measurements in isolated lung showed that alveolar liquid pressure was near the pleural pressure at a lung volume near functional residual capacity (FRC). In this study we verified that alveolar liquid pressure in vivo was similar to that of the isolated lung. In anesthetized paralyzed rabbits (3-4 kg, n = 9) ventilated with 100% O2 in the left lateral position, we made a pleural window between the fifth and sixth ribs near midchest by removing tissue down to the parietal pleura. Window height was 6 cm above the base of the lung. During apnea, alveolar liquid and pleural pressures were measured by puncturing through the pleural window with micropipettes connected to a servo-nulling pressure-measuring system. Pressures were measured at airway pressures of 0 (FRC) and 10 cmH2O both in vivo and postmortem. In vivo, alveolar liquid and pleural pressures relative to ambient pressure averaged -2.3 +/- 1.4 (SD) and -1.8 +/- 0.9 cmH2O at FRC and increased to 3.3 +/- 1.8 and 1.8 +/- 1.6 cmH2O after inflation to an airway pressure of 10 cmH2O, respectively. Similar values were obtained postmortem. These results were similar to previous measurements in the isolated lung.

Air Pressure↗
PubMed1992

Glucose-induced phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS) in isolated rat pancreatic islets.

In order to further evaluate the role of protein kinase C activation in glucose-induced insulin secretion, the extent of phosphorylation of the myristoylated alanine-rich C kinase substrate (MARCKS) was examined in freshly isolated rat pancreatic islets prelabeled with [32P]orthophosphate. The islets were incubated with either 2.75 mM glucose alone, 2.75 mM glucose + 1 microM phorbol myristate acetate, 20 mM glucose, or 20 mM glucose + 50 nM staurosporine. After stimulation, the homogenized islets were processed by immunoprecipitation with a specific polyclonal anti-MARCKS antibody, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Densitometric analysis of autoradiograms revealed that phorbol myristate acetate caused a 3.78 +/- 0.97-fold increase in MARCKS phosphorylation over control. In the islets exposed to 20 mM glucose, an increase of 3.43 +/- 0.46-fold over control was observed. In islets exposed to G20 + 50 nM staurosporine, MARCKS phosphorylation was inhibited by 90 +/- 4% compared with control islets exposed to 20 mM glucose alone. Islets similarly treated (but incubated without 32P) were examined by immunocytochemistry using an alpha-PKC-specific monoclonal antibody and visualized by confocal immunofluorescence microscopy. The alpha-PKC redistributed from the cytosol to the plasma membrane in the beta-cells of islets exposed to 20 mM glucose. In separate experiments, unlabeled but similarly treated islets were shown to respond with a 5-7-fold increase in insulin secretion in static incubation. Thus, when freshly isolated rat pancreatic islets are exposed to stimulatory glucose concentrations, they exhibit both a translocation of alpha-PKC and a significant increase in the extent of phosphorylation of MARCKS protein. These data suggest that alpha-PKC is activated during glucose-induced insulin secretion.

Alkaloids↗
PubMed1992

Immunocytochemical localization of alpha-protein kinase C in rat pancreatic beta-cells during glucose-induced insulin secretion.

To investigate the role of protein kinase C (PKC) in the regulation of insulin secretion, we visualized changes in the intracellular localization of alpha-PKC in fixed beta-cells from both isolated rat pancreatic islets and the pancreas of awake unstressed rats during glucose-induced insulin secretion. Isolated, perifused rat islets were fixed in 4% paraformaldehyde, detergent permeabilized, and labeled with a mAb specific for alpha-PKC. The labeling was visualized by confocal immunofluorescent microscopy. In isolated rat pancreatic islets perifused with 2.75 mM glucose, alpha-PKC immunostaining was primarily cytoplasmic in distribution throughout the beta-cells. In islets stimulated with 20 mM glucose, there was a significant redistribution of alpha-PKC to the cell periphery. This glucose-induced redistribution was abolished when either mannoheptulose, an inhibitor of glucose metabolism, or nitrendipine, an inhibitor of calcium influx, were added to the perifusate. We also examined changes in the intracellular distribution of alpha-PKC in the beta-cells of awake, unstressed rats that were given an intravenous infusion of glucose. Immunocytochemical analysis of pancreatic sections from these rats demonstrated a glucose-induced translocation of alpha-PKC to the cell periphery of the beta-cells. These results demonstrate that the metabolism of glucose can induce the redistribution of alpha-PKC to the cell periphery of beta-cells, both in isolated islets and in the intact animal, and suggest that alpha-PKC plays a role in mediating glucose-induced insulin secretion.

Animals↗