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Biomedical subjects

S Ghoshal

Publications and source records attributed to S Ghoshal.

32 records · Page 2Linked to original sources
PubMed1994

Low dose rate vs. high dose rate brachytherapy in the treatment of carcinoma of the uterine cervix: a clinical trial.

PURPOSE: This study is a prospective randomized clinical trial undertaken at our center to compare low dose rate versus high dose rate intracavitary brachytherapy for the treatment of carcinoma uterine cervix. METHODS AND MATERIALS: From June 1986 to June 1989, 482 patients with previously untreated invasive squamous cell carcinoma of the uterine cervix were entered into the study. After an initial clinical examination and investigative work-up the patients were staged according to FIGO staging system. Depending upon the stage of the disease, the size of the local growth and the local cervical anatomy, the patients were divided into two main groups. In group I patients, the predominant treatment was by intracavitary therapy and in group II patients, the predominant therapy was by external beam radiation. In both the groups at the time of intracavity brachytherapy the patients were alternately randomized to receive either low dose rate or high dose rate brachytherapy. There were thus two hundred forty-six patients in the low dose rate group and two hundred thirty-six patients in the high dose rate group. The patients were analyzed for local control, 5 years survival and late radiation morbidity. RESULTS: Stage for stage the local control rates in the low dose rate group and high dose rate group were similar. The overall local control achieved in the low dose rate group was 79.7% as compared to 75.8% in the high dose rate group. The 5 years survival figures in the low dose rate and high dose rate group were also comparable. In Stage I, it was 73% for low dose rate patients and 78% for high dose rate patients, for Stage II it was 62% and 64% respectively and for Stage III patients it was 50% and 43%. The only statistically significant difference was found in the incidence of overall rectal complications which was 19.9% for the low dose rate group as compared to only 6.4% for the high dose rate group. However, the more severe grade 3-4 complications were not significantly different between the two groups (2.4% vs. 0.4%, respectively). The bladder morbidity in both the groups was similar. CONCLUSION: Thus high dose rate intracavitary brachytherapy is an equally good alternative to conventional low dose rate brachytherapy in the treatment of carcinoma of the uterine cervix.

Brachytherapy↗
PubMed1994

A computational model with ionic conductances for the fusiform cell of the dorsal cochlear nucleus.

A computational model of a fusiform cell of the dorsal cochlear nucleus was developed. The results of model simulations are compared with the results of in vitro experimental observations obtained by other investigators. The structure of the present model is similar to that of Hodgkin-Huxley [J. Physiol. 117, 500-544 (1952)]. The model incorporates five nonlinear voltage-dependent conductances (three potassium and two sodium types) and their associated equilibrium-potential batteries, a leakage conductance, the membrane capacitance, and a current source. Model responses were obtained under both current- and voltage-clamp conditions. When a hyper- and depolarizing current sequence was applied [Manis, J. Neurosci. 10, 2338-2351 (1990)], the cell model was able to reproduce builduplike and pauserlike discharge patterns closely resembling Manis' observations. A transient "A"-type potassium conductance in the model played a major role in generating this phenomenon. The model predicts that blocking the "A" conductance should convert a builduplike or pauserlike pattern into a sustained regular pattern. A persistent sodium conductance in the model played the main role in reproducing: Spontaneous regular discharge; a discharge after a long latency under a long small (+0.025 nA) current; and nonlinear voltage-current characteristics with positive currents. Usefulness of the model can be seen as follows: (1) Several sets of experimental observations can be integrated into a common framework; (2) possible roles of different ionic conductances postulated to be present in the cell can be inferred by observing the model behavior with the conductances intact or blocked; and (3) time courses of ionic currents and conductance values obtained from the model under current- and voltage-clamp conditions can serve as predictions to be tested in future experimental studies.

Cochlea↗
PubMed1992

Amplitude-modulated tone encoding behavior of cochlear nucleus neurons: modeling study.

A recent study of amplitude-modulated (AM) tone encoding behavior of dorsal and posteroventral cochlear nucleus (DCN and PVCN) neurons by Kim et al. [Hear. Res. 45, 95-113, 1990] observed that certain neurons (e.g., pause/build type-III neurons and chop-S neurons) tended to exhibit band-pass modulation transfer functions (MTFs) and intrinsic oscillations (IOs) whereas certain other neurons (e.g., chop-T neurons) tended to exhibit low-pass MTFs and no IOs. The goal of the present study was to develop models of these response characteristics in an attempt to understand the underlying neuronal mechanisms. We hypothesized that chopper neurons corresponded to stellate cells and pause/build neurons corresponded to fusiform cells. We also hypothesized that, with right input combination, appropriate models of a single stellate and fusiform cell could account for band-pass and low-pass MTFs as well as the associated IOs. The neuron models developed by Arle and Kim [Biol. Cybern. 64, 273-283, 1991] for the stellate and fusiform cells were used in this study. The models are modified versions of MacGregor type neuron model incorporating cell-specific nonlinear voltage-dependent conductances. The AM tone excitation via the auditory nerve fibers was represented by a current at the soma of the neuron model, which consisted of dc, ac and a zero-mean Gaussian noise. The dc, ac and noise represent a high-frequency carrier beyond the neuron's phase-locking limit, an envelope, and randomness of the system, respectively. With systematic variation of dc, ac and noise amplitudes, we observed the following: the band-pass MTF behaviors of pause/build and chop-S neurons were reproduced by the fusiform cell model and the stellate cell model with a strong dc/noise ratio, respectively. The low-pass MTF behavior of a chop-T neuron was reproduced by the stellate cell model with a weak dc/noise ratio. It was observed that the stellate cell model was more susceptible to the noise, in the sense that an increase in noise tended to abolish the IO and change the MTF of the model from band-pass to low-pass more readily in the stellate cell model than in the fusiform cell model. Kim et al. (1990) observed a close correlation between the IO frequency and the best envelope frequency (BEF). In the models, a similar correlation was observed between the two measures for both the stellate and fusiform cell models.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1992

Yeasts at different mucosal sites in patients with carcinoma cervix before and following radiotherapy.

The yeasts isolated from four superficial sites and blood were studied before and during radiotherapy in patients with carcinoma of the cervix. Significant yeast growth increased markedly in all four superficial sites during the 1st and 2nd week following radiotherapy. By the 4th week the count had decreased in all samples except in stool of 4 patients. Candida albicans was the most frequent isolate (54.3%) followed by C. tropicalis (28.3%).

Candida↗
PubMed1991

Local thermo-radiotherapy in carcinoma cervix: improved local control versus increased incidence of distant metastasis.

In 1986, 50 patients with stages II and III carcinoma of the cervix were entered into this prospective randomized study. Twenty-five cases (Group I) were treated only by radical radiation whereas remaining 25 cases (Group II) received local hyperthermia in addition to radical radiation. Hyperthermia was delivered by intracavitary brachyhyperthermia approach using an endotract applicator. Both the groups were followed up for a minimum period of 18 months. Group II patients achieved better local control (14 out of 20 evaluable cases) than the Group I patients (11 out of 22 evaluable cases). A disturbing observation was the increased incidence of distant metastasis in Group II (4 out of 23 cases) as compared to Group I (1 out of 23 cases), though most of them remained disease free locally. The increasing use of hyperthermia in the management of various cancers needs to be reviewed in this context.

Brachytherapy↗
PubMed1991

Carcinoma of the esophagus presenting with esophagocutaneous fistula--a case report.

An interesting manifestation of carcinoma of the esophagus, hitherto undescribed is reported. The patient at the time of diagnosis had presented with an esophagocutaneous fistula. He was treated by feeding jejunostomy and local palliative radiotherapy and showed good clinical improvement. The extreme rarity of such a presentation is highlighted.

Adult↗
PubMed1990

Occult carcinoma esophagus metastatic to spine producing paraplegia--a case report and review of literature.

An extremely rare case of asymptomatic squamous cell carcinoma of the esophagus metastatic to the spine leading to paraplegia is reported. The rarity of such an event signifies the relationship between hypercalcaemia and carcinoma of the esophagus. Its occurrence as a second silent primary neoplasm and its association with a negative esophagogram is highlighted.

Carcinoma, Squamous Cell↗
PubMed1989

Evidence for selection of virulent sub-populations of Entamoeba histolytica by cholesterol.

Quantitatively much higher Concanavalin A (Con. A) agglutinability, haemolytic potency, and activities of acid hydrolases, namely phosphatase (EC 3.1.3.2), ribonuclease (EC 2.7.7.16), deoxyribonuclease (EC 3.1.4.5) and proteinase--were observed in a virulent strain of Entamoeba histolytica (IP-106), as compared to attenuated and avirulent strains (200-NIH) and DKB respectively. In addition, significant differences in these parameters were observed among clonal cultures derived from the latter two cultures by cultivation of single amoebic cells picked out by micromanipulation. Repeated sub-culturing of parent cultures of both these strains in cholesterol-enriched medium resulted in marked enhancement of all the above activities, but no such change occurred in the derived clonal cultures following similar cholesterol treatment. The implication of these findings in relation to enhancement of the virulence of E. histolytica by cholesterol is discussed.

Acid Phosphatase↗
PubMed1987

Cholesterol induced changes in glucose-6-phosphate generating enzymes, concanavalin A agglutinability and haemolytic activity of axenic Entamoeba histolytica.

Repeated passage of the 200-NIH strain of Entamoeba histolytica through cholesterol-enriched axenic growth medium induced marked increases in cholesterol, phosphoglucomutase and hexokinase levels and a less prominent rise in the protein content of amoebic cells. There was also pronounced enhancement of haemolytic activity and Concanavalin A (Con A) agglutinability of the culture, but no significant change was observed in glucose phosphate isomerase. These cholesterol-induced effects persisted to a large extent when amoebae were subsequently repassaged through normal axenic medium lacking exogenous cholesterol, but changes in cellular cholesterol and protein levels did not persist. Qualitatively similar results were obtained whether the sterol was layered as a film on the glass walls of the culture tubes or supplied as sonicated micells, but the latter was in general more effective.

Agglutination↗
PubMed1976

Restoration of virulence to rat of axenically grown Entamoeba histolytica by cholesterol and hamster liver passage.

A virulent strain of Entamoeba histolytica (NIH-200) from a symptomatic human case, cultured in vitro for more than three years, was unable to infect rat caecum or hamster liver. When grown with a mixed bacterial flora, it infected rat caecum but did not produce ulceration. After passaging amoebae growing with bacteria in hamster liver, amoebic hepatic lesions were regularly produced. The amoebae from liver lesions produced ulceration in the caeca of rats. Expoxure to cholesterol of amoebae growing with bacteria or feeding rats orally with cholesterol and injecting these amoebae along with bacteria also led to the production of ulcers in rats. Thus virulent amoebae which have been cultured in vitro for a long time become attenuated but their virulence can be revived.

Animals↗
PubMedDate not supplied

Side-effects of local hyperthermia: results of a prospectively randomized clinical study.

In 1986, 25 patients with stage II and III carcinoma of the cervix were treated by a combination of radiation and local hyperthermia using an endotract intravaginal applicator. Another 25 patients were treated with radiation alone. Both groups were followed up for a minimum period of 18 months. The acute and long-term toxicity of local hyperthermia was closely monitored. Our study shows that whereas local hyperthermia adds significantly to the local control achieved with radiation alone, it is not in any way associated with any significant short- or long-term toxicity, and does not enhance the radiation reactions.

Combined Modality Therapy↗
PubMedDate not supplied

Matrix management: not a structure, a frame of mind.

In many of the world's leading corporations, strategic thinking has outdistanced organizational capability. As business challenges have grown more complex over the past 20 years, most companies have avoided the trap of one-dimensional strategic responses-stick to your knitting, stick to the big markets. But many of them have fallen into a second, structural trap and adopted elaborate organizational matrices that actually impair their ability to implement sophisticated strategies. Keeping a company light on its feet strategically while still coordinating its activities across divisions, functions, even continents, means eliminating parochialism, improving communications, and weaving the decision-making process into the company's social fabric. Altering formal structure from the top down is a poor way to achieve these goals. It is easier to work from the bottom up, focusing on the attitudes and behavior of individual managers. The companies that have made best use of this focus-among them NEC, Philips, and Unilever-employ three techniques to capture the capabilities and commitment of each manager: 1. They communicate a clear, consistent corporate vision. 2. They use training and career-path management to broaden individual perspectives and increase identification with corporate goals. 3. They co-opt individual energies and ambitions into the broader corporate-wide agenda. The goal is to build a matrix of corporate values and priorities in the minds of managers and let them make the judgments and negotiate the deals that make strategy pay off.

Industry↗
PubMedDate not supplied

What is a global manager?

To compete around the world, a company needs three strategic capabilities: global-scale efficiency, local responsiveness, and the ability to leverage learning worldwide. No single "global" manager can build these capabilities. Rather, groups of specialized managers must integrate assets, resources, and people in diverse operating units. Such managers are made, not born. And how to make them is--and must be--the foremost question for corporate managers. Drawing on their research with leading transnational corporations, Christopher Bartlett and Sumantra Ghoshal identify three types of global managers. They also illustrate the responsibilities each position involves through a close look at the careers of successful executives: Leif Johansson of Electrolux, Howard Gottlieb of NEC, and Wahib Zaki of Procter & Gamble. The first type is the global business or product-division manager who must build worldwide efficiency and competitiveness. These managers recognize cross-border opportunities and risks as well as link activities and capabilities around the world. The second is the country manager whose unit is the building block for worldwide operations. These managers are responsible for understanding and interpreting local markets, building local resources and capabilities, and contributing to--and participating in--the development of global strategy. Finally, there are worldwide functional specialists--the managers whose potential is least appreciated in many traditional multinational companies. To transfer expertise from one unit to another and leverage learning, these managers must scan the company for good ideas and best practice, cross-pollinate among units, and champion innovations with worldwide applications.

Administrative Personnel↗