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Biomedical subjects

Z Ram

Publications and source records attributed to Z Ram.

At least 19 recordsLinked to original sources

In vivo gene transfer with retroviral vector-producer cells for treatment of experimental brain tumors.

Direct in situ introduction of exogenous genes into proliferating tumors could provide an effective therapeutic approach for treatment of localized tumors. Rats with a cerebral glioma were given an intratumoral stereotaxic injection of murine fibroblasts that were producing a retroviral vector in which the herpes simplex thymidine kinase (HS-tk) gene had been inserted. After 5 days during which the HS-tk retroviral vectors that were produced in situ transduced the neighboring proliferating glioma cells, the rats were treated with the anti-herpes drug ganciclovir. Gliomas in the ganciclovir- and vector-treated rats regressed completely both macroscopically and microscopically. This technique exploits what was previously considered to be a disadvantage of retroviral vectors--that is, their inability to transfer genes into nondividing cells. Instead, this feature of retroviruses is used to target gene delivery to dividing tumor cells and to spare nondividing neural tissue.

3T3 Cells

Delayed intraventricular tension pneumocephalus complicating posterior fossa surgery for cerebellar medulloblastoma.

A child is described in whom intraventricular tension pneumocephalus developed 10 days after removal of a cerebellar medulloblastoma and 1 day after suture removal. The tension pneumocephalus was associated with hydrocephalus and CSF leakage from the suture line. The symptoms of the pneumocephalus were rapidly progressing loss of consciousness and hemiplegia which were promptly reversed upon aspiration of the intracranial air. A large amount of intraventricular air present in the immediate postoperative period was, however, clinically silent. The characteristics of this unusual presentation, its relation to asymptomatic pneumocephalus, hydrocephalus and the preventive and therapeutic measures required to deal with such conditions are discussed.

Cerebellar Neoplasms

Vascular insufficiency quantitatively aggravates diabetic neuropathy.

The effect of lower-limb ischemia on the severity of neuropathy was examined in 48 diabetic patients with peripheral vascular disease. The severity of the vascular disease, as determined by medical history, physical findings, and laboratory data, was scored for each leg. Neuropathy was rated clinically and based on the results of nerve conduction studies of the common peroneal, posterior tibial, and sural nerves. A significant correlation was found between the vascular scores and neurologic variables of the two legs, most strikingly so in electrophysiologic data, with coefficients of .6 to .7. Nondiabetic control patients showed no evidence of neuropathy, regardless of the severity of ischemia, whereas diabetic controls without limb ischemia showed symmetrical neuropathy. These findings support the hypoxic theory in the pathogenesis of diabetic neuropathy.

Adult

Vasospasm due to massive subarachnoid haemorrhage--a rat model.

Although the pathophysiology of chronic cerebral vasospasm following subarachnoid haemorrhage (SAH) is still unclear, it is certain that the amount of subarachnoid blood is predictive of the severity of cerebral vasospasm. Accordingly, massive subarachnoid haemorrhage (greater than 0.5 ml) was induced in adult rats via direct injection into the cisterna magna. Compared to other previously published models of experimental SAH in rats a much larger amount of blood was injected. The basilar artery was exposed 72 hours post subarachnoid haemorrhage and photographed under controlled conditions. The diameter of the artery was assessed by an image analyzer. A 50% reduction in diameter was found in 25 rats subjected to SAH as compared to 9 control rats and 4 rats with intracisternal saline injection. We conclude that when massive subarachnoid haemorrhage is induced, and direct measurements of the basilar artery are made, the rat can be used as a reliable model for investigation of SAH induced arterial vasospasm.

Animals

The influence of pyridostigmine administration on human neuromuscular functions--studies in healthy human subjects.

Pyridostigmine has a protective effect against organophosphate poisoning when given in a dosage of 30 mg three times daily causing 20-40% cholinesterase inhibition. To test its safety in the human neuromuscular system, a double-blind study on 35 subjects divided into two matched groups was performed. One group was treated with pyridostigmine in a dose of 30 mg three times daily and the other group was treated similarly with placebo, both for a 10-day period. The resultant average cholinesterase inhibition in the treatment group was 23%. Muscle strength and endurance were tested before, during (on the 8th day), and after treatment. Electrodiagnostic studies, including nerve conduction, electromyography, and response to repetitive stimulation, were carried out on four subjects of the treatment group and on two subjects of the placebo group, both before and during treatment (eighth day). Isometric handgrip strength, isokinetic elbow flexor, and extensor strength did not differ between groups as a result of the treatment. Knee flexor and extensor isokinetic strength showed a small (but statistically significant) trend to improve more during placebo treatment, whereas knee extensor endurance decreased slightly in the placebo group. Both these effects are probably due to large fluctuations in performance of the placebo group, whereas the treatment group performance was quite constant. They probably do not represent any adverse effect of pyridostigmine. No electrophysiological changes were found in any of the subjects during treatment. We conclude that pyridostigmine does not cause any significant neuromuscular effect in healthy subjects when taken in a dosage of 90 mg daily for 8 days, causing 20-30% inhibition of cholinesterase.

Adolescent

Postoperative spinal epidural empyema. Clinical and computed tomography features.

Epidural empyema is a rare complication of elective spinal surgery. Four such cases are described. The clinical features of this postoperative complication were surprisingly vague and misleading. Fever was uncommon. Local inflammatory signs or rapid neurologic deterioration were absent. Computerized tomography proved useful in diagnosis and follow-up. Unlike spontaneous spinal epidural abscess, postoperative spinal epidural empyema had a benign course. Causative bacteria were miscellaneous. Surgical evacuation of the purulent collection and appropriate antibiotic therapy resulted in cure in all cases.

Adult

Magnesium sulfate reverses experimental delayed cerebral vasospasm after subarachnoid hemorrhage in rats.

We induced experimental delayed cerebral vasospasm by the intracisternal injection of greater than 0.5 ml blood in 30 rats. Seventy-two hours later the basilar artery was exposed via the transclival approach and photographed at high-power magnification through an operating microscope. We then evaluated the effect of topical (n = 30) and intravenous (n = 20) magnesium sulfate on the spastic artery by computerized image analysis. A greater than 50% reduction in baseline diameter of the basilar artery was observed in the rats subjected to subarachnoid hemorrhage compared with the 10 controls (p less than 0.0001). Intravenous magnesium sulfate dilated the spastic artery to approximately 75% of the baseline diameter in control rats (p less than 0.0001). Topical magnesium sulfate caused dramatic dilation of the basilar artery in both the control and the subarachnoid hemorrhage groups to near 150% of the baseline diameter in the controls (p less than 0.001). All rats receiving intravenous magnesium sulfate reached therapeutic plasma levels of the ion. Hemodynamic effects were mild and immediately reversible upon cessation of magnesium sulfate administration. We suggest that magnesium has a role in the treatment of subarachnoid hemorrhage-induced vasospasm in humans.

Animals

Another complication of thoracostomy--perforation of the right atrium.

Tube thoracostomy is an invasive procedure that is frequently life-saving but carries a risk of complications. We describe herein a complication not documented before-laceration of the right atrium. This occurred in a severely kyphoscoliotic patient with a markedly narrowed chest and led to his demise. This case attests to the extreme caution warranted when using trocar-type thoracostomy in patients with thoracic deformities.

Aged

MR demonstration of spontaneous acute epidural hematoma of the thoracic spine.

Two patients with spontaneous epidural hematoma of the thoracic spine are presented. The magnetic resonance (MR) examination performed within the first hours following the onset of symptoms demonstrated an epidural elongated lesion impinging on the spinal cord, compatible with hematoma. In one of the patients this finding was surgically confirmed. The second patient improved under steroid treatment. The MR findings were highly suggestive of the pathological nature of the lesion. The MR examination should replace other diagnostic procedures, such as computerised tomography (CT) and myelography.

Acute Disease

Intratumoural cyst formation in pituitary macroadenomas.

Twenty-one patients with various types of pituitary macroadenomas underwent hypophysectomy at the Chaim Sheba Medical Centre between 1985 to 1987. Intraoperative fine needle aspiration of the tumoural content was attempted prior to tumour excision. Although none of the patients had a history compatible with pituitary apoplexy, intratumoural fluid suggestive of a cyst within the tumour was found in 57% of the patients. Analysis of the hormones in the aspirated fluid revealed variable elevations in hormone levels, some reaching 3,000 times the equivalent plasma levels. Concomitant elevated levels of other pituitary hormones found in the cyst fluid support the concept of mixed secretory potential of pituitary adenomas, including the apparently non-functioning tumours. Six out of seven patients (86%) who received preoperative treatment with bromocriptine had an intratumoural cyst while only seven out of fourteen patients (50%) who were not treated with this drug prior to surgery had a cyst within the tumour. The implications of these observations on current theories concerning the pathophysiology of pituitary adenomas are discussed.

Adenoma

Upward transtentorial herniation: a complication of postoperative edema at the cervicomedullary junction.

Local edema at the operative bed developed a few hours after uneventful subtotal removal of a lesion occupying the lower medulla and upper cervical cord. The patient experienced apnea, quadriplegia, and circulatory collapse followed by acute respiratory insufficiency. Hydrocephalus secondary to aqueductal occlusion occurred on the 3rd postoperative day. A computerized tomographic scan was compatible with upward transtentorial herniation. The association of this phenomenon with an intra-axial lesion at the cervicomedullary junction has not been previously documented. The pathophysiological mechanisms implicated in this complication are discussed.

Adult

Delayed postoperative neurological deterioration from prolonged sodium nitroprusside administration. Case report.

Sodium nitroprusside is commonly used for the induction of hypotension during neurosurgical procedures. Its toxicity stems from hemodynamic compromise as well as from its metabolites, especially the formation of cyanide. A patient is described who underwent craniotomy for hypertensive intracerebral hemorrhage. He gradually recovered following the operation, but needed continued administration of sodium nitroprusside for control of hypertension. On the 7th postoperative day, he deteriorated into coma with evidence of severe edema and herniation on the computerized tomography scan. Cessation of sodium nitroprusside and treatment for cyanide poisoning resulted in resolution of his symptoms within hours. The potential toxicity of sodium nitroprusside, measures to prevent toxicity, and therapeutic steps are discussed.

Brain Edema

Delayed nonhemorrhagic encephalopathy following mild head trauma. Case report.

Delayed nonhemorrhagic encephalopathy following mild head trauma is a rare condition with an unknown etiology. The few cases reported in the literature are in young adults, all of them in the era before computerized tomography (CT) became available, and all had a devastating clinical course with multifocal ischemia or necrotic lesions found at autopsy. A case is presented of a young man with this syndrome who survived the acute encephalopathic phase with severe residual neurological deficits. Repeat CT scans during and following the acute phase as well as magnetic resonance imaging showed diffuse multifocal lesions compatible with ischemic changes and demyelination in the "watershed" areas of the brain.

Adult

Spinal cord involvement as the presenting symptom of acute monocytic leukemia.

Spinal cord involvement in leukemia is rare and has been described only once in association with acute monocytic leukemia. A patient whose presenting symptom of acute monocytic leukemia was the syndrome of cauda equina compression due to an epidural and retroperitoneal leukemic mass is reported. Peripheral blood smears were normal throughout the evolution of the disease. The radiological, surgical, and pathological findings are presented, and the therapeutic, along with the prognostic implications of spinal cord involvement by leukemia are discussed.

Adult