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Biomedical subjects

A Goel

Publications and source records attributed to A Goel.

At least 55 records · Page 3Linked to original sources
PubMed2000

Reconstruction of the skull base: a review of personal techniques.

With increasing technological and surgical sophistication in cranial base and craniofacial surgery, reconstructive efforts are challenged to provide a reliable means of compartmentalisation. Some improvised methods of basal reconstruction with vascularised pedicle flap are described in this presentation. The dependable blood supply, long length, ease of harvesting and the ability to alter the arc of rotation of the described flaps make them versatile for lining skull base. The flaps may be used to cover defects, may be folded for bulk and may be used to carry blood supply to poorly vascularised recipient sites. The techniques are presented.

Humans↗
PubMed2000

Comparison of two radiation dose schedules in post mastectomy carcinoma of the breast.

In 108 histopathologically proved breast cancer patients, after surgical treatment with modified radical mastectomy, two radiation dose schedules have been compared. Radiation therapy was given on a 60Co teletherapy machine using gent pair technique for chest wall irradiation and direct fields for lymphatic drainage areas. The patients were randomly divided into two groups (Group A and Group B). 54 patients were given external radiotherapy 40 Gy/17 F/3.2 weeks and remaining 54 patients were given 45 Gy/20 F/4 weeks. Results of treatment in Group A versus Group B were as follows; chest wall failure 5/50(10%) versus 3/54 (5.6%), axillary lymphnods failure 3/50(6%) versus 4/54(7%), distant metastasis 16/50(32%) versus 15/54(28%). Radiation reactions were almost similar in both the groups. Skin reactions were most common radiation effects [45/50 (90%) in Group A and 43/54 (79.6% in Group B]. Thus no statistically significant difference in local control and efficacy of these two radiation dose schedules was observed in postmastectomy carcinoma of the breast.

Adult↗
PubMed2000

Preoperative shunts in thalamic tumours.

Thirty one patients with thalamic glioma underwent a pre-tumour resection shunt surgery. The procedure was uneventful in 23 patients with relief from symptoms of increased intracranial pressure. Eight patients worsened after the procedure. The level of sensorium worsened from excessively drowsy state to unconsciousness in seven patients. Three patients developed hemiparesis, 4 developed paresis of extra-ocular muscles and altered pupillary reflexes, and 1 developed incontinence of urine and persistent vomiting. Alteration in the delicately balanced intracranial pressure and movements in the tumour and vital adjacent brain areas could be the probable cause of the worsening in the neurological state in these 8 patients. On the basis of these observations and on review of literature, it is postulated that the ventricular dilatation following an obstruction in the path of the cerebrospinal fluid flow by a tumour could be a natural defense phenomenon of the brain.

Adolescent↗
PubMed1999

Metabolic fluxes, pools, and enzyme measurements suggest a tighter coupling of energetics and biosynthetic reactions associated with reduced pyruvate kinase flux.

In this study, it is found that, for Bacillus subtilis, citrate-glucose cometabolism leads to zero acid production over a wide range of growth rates and nearly theoretical carbon yield. Experimental results are presented that point to pyruvate kinase (PYK) as a site of citrate-mediated glycolytic flux attenuation. First, the measured fluxes show that, compared with cultures grown on glucose, the PYK flux drops by more than tenfold when citrate is added. Second, relative to cultures metabolizing glucose, the phosphoenolpyruvate (PEP) pool elevates substantially, whereas the pyruvate pool drops, when citrate is present. Finally, our modeling results indicate that maximizing carbon yield corresponds to nearly eliminating pyruvate kinase (PYK) flux and that the pyruvate supplied by the PEP-consuming glucose transport system can supply the biosynthetic requirements. A literature review suggests some mechanisms for how PYK attenuation by citrate addition can occur. At this juncture, we hypothesize that direct PYK inhibition occurs which, in turn, also leads to phosphofructokinase inhibition via the elevated PEP pool. These two inhibition events combine to throttle glycolytic flux; minimize acid formation; and substantially increase cellular, product, and energetic yields.

Bacillus subtilis↗
PubMed1999

Present status of hepatoprotectants.

Perpetual exposure of liver to xenobiotics and therapeutic agents leads to toxic manifestations of a complex and diverse nature. Not a single curative therapeutic agent has been found so far which could provide lasting remedy to patients suffering from hepatic disorders. In fact, the remedies available in the modern system of medicine provide only symptomatic relief without any significant changes on the disease process. Moreover, their use is associated with severe side effects and chances of relapses. Except some natural products claimed to be effective, no safe synthetic product is yet available for the management of hepatic disorders. Lack of effective, least toxic and curative hepatoprotectants made the task difficult to discover newer drugs. This review is an attempt to provide an overall view of the development of synthetic and natural products as hepatoprotective agents.

Animals↗
PubMed1999

Purification and properties of a novel raw starch degrading cyclomaltodextrin glucanotransferase from Bacillus firmus.

A novel raw starch degrading cyclomaltodextrin glucanotransferase (CGTase; E.C. 2.4.1.19), produced by Bacillus firmus, was purified to homogeneity by ultrafiltration, affinity and gel filtration chromatography. The molecular weight of the pure protein was estimated to be 78,000 and 82,000 Da, by SDS-PAGE and gel filtration, respectively. The pure enzyme had a pH optimum in the range 5.5-8.5. It was stable over the pH range 7-11 at 10 degrees C, and at pH 7.0 at 60 degrees C. The optimum temperature for enzyme activity was 65 degrees C. In the absence of substrate, the enzyme rapidly lost its activity above 30 degrees C. K(m) and kcat for the pure enzyme were 1.21 mg/ml and 145.17 microM/mg per minute respectively, with soluble starch as the substrate. For cyclodextrin production, tapioca starch was the best substrate used when gelatinized, while wheat starch was the best substrate used when raw. This CGTase could degrade raw wheat starch very efficiently; up to 50% conversion to cyclodextrins was obtained from 150 g/l starch without using any additives. The enzyme produced alpha-, beta- and gamma-cyclodextrins in the ratio of 0.2:9.2:0.6 and 0.2:8.6:1.2 from gelatinized tapioca starch and raw wheat starch with 150 g/l concentration respectively, after 18 h incubation.

Bacillus↗
PubMed1999

Strain-specific recognition of live Leishmania donovani promastigotes by homologous antiserum raised against a crude membrane fraction of infected macrophages.

Surface antigens on Leishmania promastigotes and infected macrophages are obvious targets in immunoprophylaxis for leishmanial infection. We have recently demonstrated that the polyclonal antiserum and monoclonal antibodies generated by homologous immunizations with the crude membranes of parasite-infected cells react effectively with the 'neo-antigenic' determinants on the infected cell surface. In the present study, we investigated the utility of such polyclonal antisera for identifying 'minor' surface components of promastigotes. The reactivity of anti-Leishmania donovani-(strain RMRI68) infected macrophage membrane (anti-IMm) antiserum was compared with that of anti-promastigote (anti-Pr) antiserum towards the infected macrophage surface and promastigotes of three Indian strains of L. (donovani, RMRI68, AG83 and DD8. While anti-Pr antiserum showed no reactivity with the infected macrophage surface but reacted strongly with air dried and live promastigotes of all three strains, anti-IMm antiserum reacted with the infected cell surface and, interestingly, specifically recognized live promastigotes of the strain used for infection, i.e., strain RMRI68. The reactivity patterns of the two antisera with the immunodominant components of the L. donovani promastigote surface, i.e., purified LPG-KMP11 complex and gp63 molecules, indicated that unlike anti-Pr antiserum, the specificities in anti-IMm antiserum were mainly directed towards molecules other than the LPG-KMP11 complex and gp63. Antiserum generated in a similar fashion against the macrophage membrane of cells infected in vitro with strain AG83 also contained antibodies specific to strain AG83 promastigotes. The present approach may therefore greatly help in identifying specific antigen(s) important in clinical and epidemiological control of leishmaniasis.

Animals↗
PubMed1999

Basal lateral subtemporal approach for trigeminal neurinomas: report of an experience with 18 cases.

Subtemporal craniotomy centred on the external ear canal was used to surgically treat 18 trigeminal neurinomas. The approach was found to be suitable to deal with either or both the middle fossa and the posterior cranial fossa components of the tumour. The basal extension of the exposure was achieved by resection of the roots of the zygomatic arch, roof of the external ear canal and superior third of the mastoid bone. The temporalis muscle was rotated anteriorly. The direction of the approach to the tumour was the shortest and perpendicular from the surface and avoided any neural or vascular exposure or manipulation. The basal exposure was horizontally wide and significantly low which reduced the operating distance, limited the extent of temporal lobe retraction and provided additional space for manipulation of instruments. The exposure was manoeuvreable with anterior, posterior and medial expansion being possible during or prior to tumour resection. The approach had the advantage of being simple and relatively quick and of its familiarity to general neurosurgeons. The experience with the approach with trigeminal neurinomas and its possible advantages over other available approaches to these lesions are analysed in this report.

Adult↗
PubMed1999

Meralgia paresthetica secondary to limb length discrepancy: case report.

Meralgia paresthetica consists of pain and dysthesia in the lateral thigh caused by entrapment of the lateral femoral cutaneous nerve (L2-L3) underneath the inguinal ligament. Abdominal distension, tight clothing, and hip hyperextension are all described causes of this condition. To our knowledge this has never been attributed to a limb length discrepancy. We present a 51-year-old man with a long-standing history of right sided meralgia paresthetica. History and physical and radiological examination were unrewarding except that his left leg was shorter than the right by 2 cm. Nerve conduction studies of the lateral femoral cutaneous nerve on the left had a normal latency and amplitude but were absent on the right. To prove the hpothesis that the limb length discrepancy was responsible for the condition, a single subject study was performed. The presence or absence of pain and dysesthesia in the right thigh was the observed behavior. Intervention consisted of wearing a 1.5-cm lift in the left or right shoe for 2 weeks each with an intervening 2-week lift-free period. Pain was recorded on a numeric scale and numbness as being present or absent. There was continuing pain without and with the lift in the right shoe but no pain or numbness with the lift in left shoe. It was concluded that the limb length discrepancy was responsible for the meralgia paresthetica. Pertinent literature and possible pathomechanics are discussed.

Femoral Nerve↗
PubMed1999

Holocord intramedullary abscess: an unusual case with review of literature.

STUDY DESIGN: A rare case of a holocord intramedullary abscess with review of literature. OBJECTIVES: Summary of clinical presentation, radiology, microbiology, etiology and management of intramedullary spinal cord abscess. Abscess involving the entire spinal cord is extremely rare and awareness of such an event could avoid delay in evacuation of the absess. METHODS: The incidence, clinical presentation, radiological investigations, treatment and etiology of intramedullary spinal cord abscess in 100 consecutive cases are discussed. RESULTS: Intramedullary spinal cord abscesses are rare. Presently, only five cases of holocord intramedullary abscess are described. In our analysis of 100 cases of intramedullary abscess, a male preponderance was found. The first and the third decades were the most common age groups. Prognosis is poor if treatment is delayed. Contrast-enhanced MRI is the ideal investigation for diagnosis. Prompt surgical drainage of the abscess with appropriate antibiotic therapy is mandatory since the natural course of the disease has a very unfavourable outcome. Staphylococcus and Streptococcus were the most common causative organisms. CONCLUSION: Intramedullary spinal cord abscess along the entire length of spinal cord is rare. A thorough history with precise clinical localisation, a high index of suspicion, contrast-enhanced MRI at appropriate level and prompt surgical drainage with appropriate antibiotic therapy are key to the eventual outcome and prognosis.

Abscess↗
PubMed1999

Fluid-fluid levels in intracranial schwannomas.

Intracranial cystic neurogenic tumours constitute an uncommon subset of tumours with a distinct clinico-biological behaviour. The presence of fluid-fluid levels within the tumours, although rare, confirms the cystic nature of the neoplasms. Barring the acoustic schwannomas, cystic cranial nerve schwannomas are exceptionally uncommon. Imaging findings of fluid-fluid levels in two non-acoustic cranial nerve schwannomas are described; one was a cystic trigeminal schwannoma and the other was a glossopharyngeal nerve schwannoma. The causes of the fluid-fluid level and its implications are analysed.

Adult↗
PubMed1999

Subversion of antigenic expression in neoplasia: lessons from immunohistology of teratomas.

Many examples of inappropriate expression of intermediate filaments and other cell identity markers are known to occur in diagnostic tumor pathology. In the present study, this subversion of antigenic differentiation in tumors has been investigated using teratomas as a model, as these unique tumors not only mimic developing tissues but also show carcinomatous elements. Ten cases of teratoma (eight immature, two mature) were studied immunohistochemically using a panel of 13 commonly used cell identity markers, including intermediate filaments. Examples of antigenic coexpression and transbarrier expression in various morphologically mature and immature tissues were noted to be similar to those seen in various tumors. Carcinomatous elements in teratomas were non-reactive rather than showing antigenic aberrations. Hence, this study strengthens the proposition that antigenic subversion in neoplasia is related to the process of maturation and differentiation, rather than malignant transformation.

Adolescent↗
PubMed1999

Extended lateral subtemporal approach for petroclival meningiomas: report of experience with 24 cases.

Subtemporal craniotomy centred on the external ear canal and its basal extension, involving resection of the roots of the zygomatic arch, roof of the external ear canal and superior third to half of the mastoid bone was used to treat surgically 24 meningiomas located in the petroclival region, having their maximum bulk at the level of tentorium. The approach was found to be suitable for dealing with middle fossa extensions of the tumour in addition to the part extending up to the mid-clivus or vertebrobasilar junctional region. The direction of the approach to the petroclival region was the shortest and most perpendicular from surface and avoided any neural or vascular exposure or manipulation. The basal exposure was horizontally wide and significantly low, which reduced the operating distance, limited the extent of temporal lobe retraction and provided additional space for manipulation of instruments. The exposure was manoeuverable with anterior, posterior and medial expansion being possible during or prior to tumour resection. The approach had the advantage of being simple and relatively quick, and of its familiarity to general neurosurgeons. The experience with the approach with petroclival meningiomas and its possible advantages over other available approaches to these lesions are analysed in this report.

Adolescent↗
PubMed1999

Trochlear nerve neurinoma presenting as pathological laughter.

A case of trochlear nerve neurinoma in a 48-year-old women is reported. She presented with pathological laughter as her principal symptom which was cured by tumour resection. A brief review of the available literature on the subject is reported.

Affective Symptoms↗
PubMed1999

A trigeminal neurinoma involving the lacrimal nerve: case report.

An isolated neurinoma involving the entire length of the lacrimal nerve is reported. The tumour was large and involved both the intracranial cavernous sinus, as well as the extracranial intraorbital part of the nerve. The patient, a 45-year-old housewife had a painless progressive proptosis associated with marginally decreased lacrimation of the affected eye. There was no evidence of neurofibromatosis.

Female↗