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Biomedical subjects

B Mehta

Publications and source records attributed to B Mehta.

At least 37 records · Page 2Linked to original sources
PubMed1991

Dominant A1: angiographic and clinical correlations with anterior communicating artery aneurysms.

It has been observed but never proven that anomalies of the anterior communicating artery complex are associated with anterior communicating artery aneurysms (ACAA). Therefore, in an effort to understand the significance of haemodynamic factors in the genesis, as well as the clinical course of ACAA, we evaluated the correlation between certain angiographic patterns of flow in the anterior circulation and the clinical findings of 51 patients with ACAA compared with 50 matched controls. Four significant associations which have never been validated were identified: 1) a dominant A1 (filling both A2's) was found in 57% of ACAA patients versus 14% of controls (p less than 0.001). 2) Unilateral hypoplasia of the opposite A1 was present in 24% of ACAA patients versus 6% of controls (p = 0.01). 3) Exclusive filling of the ACAA from one A1 occurred in 78%. 4) No statistically significant relationship was found between the anatomic flow patterns studied and the patients clinical presentation including age, sex, or grade. We conclude that anterior communicating artery aneurysms are significantly related in a majority of patients with the presence of a dominant A1, probably as the result of enhanced haemodynamic stress caused by this anatomic abnormality in the circulation. However, this association is not constant, and a dominant pattern of flow did not correlate with the clinical course. This is probably a reflection of the differences between factors initiating aneurysm formation and those influencing its growth, as well as of the relative limitations of angiography when pathophysiological extrapolations are attempted.

Adolescent↗
PubMed1990

Thrombolytic therapy and posterior circulation extracranial-intracranial bypass for acute basilar artery thrombosis. Case report.

Basilar artery thrombosis has a very poor prognosis. A 56-year-old comatose man with acute basilar artery occlusion was successfully treated with local urokinase infusion which reopened the basilar artery and revealed a midbasilar stenotic plaque. This procedure was followed by a superficial temporal artery to superior cerebellar artery anastomosis for protection of the posterior circulation.

Acute Disease↗
PubMed1990

Efficiency of the photoprocesses leading to singlet oxygen (1 delta g) generation by alpha-terthienyl: optical absorption, optoacoustic calorimetry and infrared luminescence studies.

The triplet energy of alpha-terthienyl has been determined by heavy atom-induced optical absorption: the value of 39.7 +/- 1.5 kcal/mol is consistent with earlier energy transfer work. Combining this result with calorimetric data from optoacoustic calorimetry indicates that intersystem crossing occurs with at least 90% efficiency in polar and non-polar solvents. The quantum yields for singlet oxygen formation via energy transfer from triplet alpha-terthienyl have been obtained from time-resolved measurements of its IR phosphorescence: these yields are in the 0.6-0.8 range in non-polar and polar (hydroxylic and non-hydroxylic) solvents.

Calorimetry↗
PubMed1989

Balloon embolization of nontraumatic vertebral arteriovenous fistulae in children.

Two children, aged 4 and 8 years, with nontraumatic extracranial vertebral arteriovenous fistula are described. Under general anesthesia and with fluoroscopic guidance, using a percutaneous endovascular technique, latex detachable balloons were used to successfully occlude the fistulae. The patients were monitored with somatosensory and auditory evoked potentials and kept hypotensive for 24 hours. Immediate and follow-up angiography 1 year later showed obliteration of the fistula in both patients. The management of this rare condition is discussed.

Arteriovenous Fistula↗
PubMed1989

Non-Hodgkin's lymphoma: natural cell-mediated cytotoxicity correlated with histological classification and prognosis.

Non-Hodgkin's lymphoma (NHL) patients classified according to the Rappaport classification system had depressed natural killer (NK) and NK cytotoxic factor activities, antibody-dependent cellular cytotoxicity, active killing potential as well as recycling capacity. The suppression of these activities was not related to the favorable or unfavorable prognosis of the patients. Paramaters of the NK cytotoxic status of the NHL patients did not correlate with the histology or prognosis of the disease.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1989

Extracranial skull base chondrosarcoma.

Chondrosarcoma of the skull base is a rare neoplasm. The most common presenting symptoms are hoarseness, dysphagia, and diplopia, which is associated with palsies of cranial nerves X, IX, and VI. The temporal bone is the most common site of tumor origin, followed by the sphenoid bone. These tumors must be differentiated from chordoma, chondroid chordoma, osteogenic sarcoma, enchondroma, and meningioma. Diagnosis is made by patient history, radiologic imaging, and biopsy. The treatment is surgical excision followed by radiation therapy. Five-year survival rates for grades I, II, and III are 90, 81, and 43%, respectively.

Adult↗
PubMed1987

Multiplanar CT-guided stereotaxis and 125I interstitial radiotherapy. Image-guided tumor volume assessment, planning, dosimetric calculations, stereotactic biopsy and implantation of removable catheters.

A method using Multiplanar CT-guided stereotactic biopsy and high-dose 125I interstitial radiotherapy in patients with malignant nonresectable or recurrent brain tumors is presented. Optimal interstitial radiotherapy requires careful preoperative planning, computer-assisted dosimetry, CT-guided stereotactic biopsy and implantation of catheters that will be loaded with 125I seeds. A method is presented by which the isodose curve distribution is adjusted to the tumor size, volume and axis, allowing treatment of the imaged and histologically determined border of the tumor with 60 Gy at a dose rate of 40 rad/h.

Biopsy↗
PubMed1986

Radiologic evaluation of extracranial to Sylvian middle cerebral artery bypass.

At this institution a new procedure has been developed that involves anastomosing one of the branches of the superficial temporal artery to one of the major trunks of the middle cerebral artery in the Sylvian fissure. This procedure has been performed in 22 cases to date. Clinical indications for this procedure have fallen into four major categories. This new type of anastomosis produces greater bypass flow than conventional cortical middle cerebral artery anastomoses, and may be a better therapeutic alternative in certain clinical situations. The preoperative and postoperative angiographic evaluation of these patients is discussed. The radiologic results in this series of patients are reviewed.

Adult↗
PubMed1986

Surgical correction of lesions affecting the second portion of the vertebral artery.

Substantial controversy has surrounded the diagnosis and management of vertebrobasilar ischemic events, with no consensus on the value of medical or surgical treatment of patients symptomatic with brain stem ischemia who have angiographically proven vertebral artery lesions. This report presents our experience with the surgical treatment of 12 of 88 patients with angiographically verified lesions in the vertebral artery who were symptomatic for 1 to 12 months before their evaluation. None experienced symptomatic relief with antiplatelet agents, nor did the administration of anticoagulants in 4 of the patients provide any benefit. The lesions included bilateral vertebral artery occlusion with distal reconstitution through muscular collaterals in 6 patients, unilateral vertebral artery hypoplasia with contralateral long-tailed lesions from the vertebral artery origin to C-5 in 3 patients, and severe bilateral vertebral artery origin lesions extending beyond the C-5 level in 3 patients. A vertebral endarterectomy and vertebral-carotid transposition in the second portion of the artery were successfully used to reestablish flow and obtain symptomatic relief in 10 of the 12 cases; 1 of these procedures had to be redone because of a persistent stenosis at C-4. Another patient had a saphenous vein graft from the common carotid to the vertebral artery at C-5. The remaining patient had an anastomosis of the distal external carotid to the vertebral artery at C-3, but this failed and an anastomosis of the occipital artery to the anterior inferior cerebellar artery had to be completed to reestablish flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Nizatidine: a new histamine receptor blocker in the treatment of active duodenal ulcers.

Forty-three patients with newly diagnosed duodenal ulcers were treated with a new histamine blocker, nizatidine, and with placebo. The incidence of complete endoscopic healing was 38, 74, and 82% in the nizatidine treated patients compared with 25, 37, and 50% in the placebo treated group after 2, 4, and 8 wk of treatment, respectively. Nizatidine was clearly more effective than placebo after 4 wk of treatment. The size of unhealed ulcers decreased more than 50% in 62, 50, and 50% in the nizatidine treated groups versus 27, 25, and 40% in the placebo treated groups after 2, 4, and 8 wk of treatment, respectively. The difference between the two was not statistically significant for any given period. There was a significant correlation between day pain relief and ulcer healing in both treatment groups. Nizatidine significantly improved day pain relief only after 8 wk of treatment (p less than 0.01). No patient developed any side effects as a result of nizatidine treatment, except that the serum creatinine level rose from 1.05 to 1.1 mg/100 ml but still remained within the normal accepted range. This study demonstrated that nizatidine at 150 mg po bid could be effectively used in the treatment of duodenal ulcer disease.

Clinical Trials as Topic↗
PubMed1985

Cerebral angiography and neuropsychological measurement: the twain may meet.

In a sample of 31 cerebral revascularization candidates, severity and dissemination of atherosclerosis on the cerebral angiogram were correlated with two of three global indicators of neurobehavioral impairment. Additionally, the angiographic rating was correlated with age and with an index of medical risk factors, but not with duration of the longest symptomatic episode. It seems likely that several variables, particularly collateral circulation, help to determine whether a given pattern of stenoses results in neuropsychological dysfunction and what type of behavioral deficit occurs. In many cases, the configuration of neuropsychological test scores may not directly mirror the pattern of cerebrovascular stenoses.

Adult↗
PubMed1985

Cerebral revascularization to a main limb of the middle cerebral artery in the Sylvian fissure. An alternative approach to conventional anastomosis.

Thirteen patients underwent an anastomosis of the superficial temporal artery (STA) or a saphenous vein graft to one of the secondary trunks of the middle cerebral artery (MCA). They included five patients with giant MCA trifurcation aneurysms, four patients in whom an earlier conventional STA-MCA anastomosis had become occluded, two patients who had stenosis of one of the secondary limbs of the MCA, and one patient who had a carotid-cavernous fistula. One patient had a saphenous vein graft from the common carotid artery to a secondary trunk of the MCA to bypass an occluded internal carotid artery and severely stenosed external carotid artery. The primary advantages of this procedure are that a large-caliber anastomosis to one of the secondary limbs of the MCA immediately restores flow into the MCA tree with a larger amount of vessel filling than with a standard cortical bypass, and large vessels can be used for the anastomosis. The disadvantages are that one of the secondary branches of the MCA must be occluded, the cerebral hemisphere around the Sylvian fissure must be retracted, a lumbar subarachnoid drain is needed, and the anastomosis must be performed deep within the Sylvian fissure. The procedure is a satisfactory alternative in cases in which a conventional STA-MCA anastomosis has either failed or would be less likely to succeed.

Adult↗
PubMed1985

Acute cerebral revascularization.

Fifteen patients evaluated for acute cerebral ischemia underwent acute cerebral revascularization between March, 1979, and May, 1983. Clinical presentation included crescendo transient ischemic attacks (TIA's) in eight cases, progressing neurological dysfunction in three cases, and completed nonfluctuating deficits in four cases. Nine patients received intravenous heparin but did not improve neurologically. The patients with crescendo TIA's were operated on within 4 hours of their last event; those with progressing deficits were operated on while the deficit was developing, and those with established deficits were operated on 4, 6, 9, and 12 hours, respectively, after the event began. The clinical picture for 10 patients had resolved within 10 hours after surgery. One patient with crescendo TIA's, two with progressing deficits, and two with established deficits had postoperative residual deficits, of which three were mild and two severe. One patient, who had a saphenous vein graft to the middle cerebral artery, developed an intracerebral hematoma. In this prospective noncontrolled nonrandomized study, acute cerebral revascularization was performed safely, had limited risks, and offered the potential to help some patients. Further controlled randomized studies are indicated.

Adult↗
PubMed1984

Dural arteriovenous malformations and intracranial hemorrhage.

Intracranial hemorrhage is seen less frequently with dural than with intraparenchymal arteriovenous malformations (AVMs). We report 6 cases of intracranial hemorrhage among our past 10 patients with dural AVMs. A literature search provided 27 other cases of intracranial hemorrhage from a total of 213 reported dural AVMs. Although hemorrhage was relatively infrequent (7.5%) with dural AVMs located primarily within a major venous sinus, bleeding episodes occurred in 20 of the 39 (51%) cases of malformation outside a major sinus. There was primary leptomeningeal venous drainage in all cases with hemorrhage, and a large variceal dilatation was seen in 14 cases (42%). Dural AVMs located outside a major sinus are uncommon, and they have a propensity for serious intracranial hemorrhage.

Adult↗
PubMed1983

The inability of oral leucovorin to elevate CSF 5-methyl-tetrahydrofolate following high dose intravenous methotrexate therapy.

Osteosarcoma patients free of CNS metastases are at risk for acquiring leukoencephalopathy after receiving multiple courses of high dose intravenous methotrexate followed by oral leucovorin rescue (MTX-LV). A prospective study of the adequacy of CNS rescue of MTX biochemical toxicity by oral leucovorin was undertaken in newly diagnosed neurologically normal osteosarcoma patients. Prior to surgical resection of the primary tumor, ten patients received 4 weekly courses of MTX-LV. During the fourth weekly MTX-LV treatment, 0 and 72 hr serum and CSF determinations of MTX, 5-methyl-tetrahydrofolate (5-MTHF) and LV were made. No CSF MTX was detectable at 0 hr in any patient, but a significant elevation in CSF MTX occurred in 9/9 patients at 72 hr (mean 47.2 +/- 31.8 ng/ml or 1.04 +/- 0.7 X 10(-7) M). There was no significant change in mean CSF 5-MTHF over 72 hr despite a rise in serum 5-MTHF. MTX exceeded 5-MTHF in 6/9 patients in CSF, whereas only 3/8 patients had higher MTX in the serum at 72 hr. No acute systemic or neurotoxicity was seen. The failure of oral leucovorin to consistently elevate CSF 5-MTHF levels at 72 hr in the context of significant levels of CSF MTX may result in intermittent CNS folate deficiency. The clinical and pathological syndrome of leukoencephalopathy may be related to this phenomenon and may evolve after repeated MTX-LV treatments.

Adolescent↗