Search PubMed⌕ Search

Biomedical subjects

B M Stein

Publications and source records attributed to B M Stein.

At least 91 records · Page 5Linked to original sources
PubMed1983

Spinal cord arteriovenous malformations with significant intramedullary components.

Few neurosurgeons have stressed the occurrence, manifestations, and resectability of intramedullary spinal arteriovenous malformations (AVM's). In six of 17 patients in the authors' series of operable spinal AVM's, the lesions had major intramedullary components. Three of these six patients presented with subarachnoid hemorrhage, and all had catastrophic neurological deficits which gradually improved. The hemorrhages appeared to originate from large venous varices lying adjacent to the intramedullary portion of the AVM. The mechanism explaining the sudden neurological deficit in the other three patients was presumed to be thrombosis within the venous varices associated with their AVM's. The reliability of the various radiographic procedures in identifying the intramedullary components of these AVM's is discussed. These malformations may be removed totally with a high degree of safety using microsurgical techniques. The postoperative course in this series of patients was gratifying in terms of improvement of neurological deficits. Postoperative angiography was not performed on all of these patients. However, the follow-up period averaged 5 years.

Adult↗
PubMed1982

The effects of epsilon aminocaproic acid on contractile properties and catecholamine content of rat carotid arteries.

The prevalent use of epsilon aminocaproic acid (EACA) to prevent rebleeding in the preoperative management of ruptured intracranial aneurysms raises the question of a relationship between this drug and cerebral vasospasm. The effects of EACA on the contractile properties of the rat common carotid artery were measured in vitro, and the effects of EACA on the catecholamine content of these arteries were determined qualitatively. When carotid artery segments from rats that had been infused with lactated Ringer's solution alone were incubated in the presence of 1 mM EACA, they exhibited a decrease in contractile activity brought about by the presence of either serotonin or norepinephrine, and an increase in contractile activity when potassium chloride was used. These changes were not witnessed if the arterial segments came from rats that had been infused with lactated Ringer's solution containing EACA. No effect of epsilon aminocaproic acid was found on the median effective dose values for each vasoconstrictor used. Fluorescence histochemistry showed no qualitative changes in the catecholamine content of carotid arteries following EACA treatment.

Aminocaproates↗
PubMed1981

Measurement of fibrinolytic activity after epsilon-aminocaproic acid administration in rats (Rattus norvegicus).

The antifibrinolytic agent, epsilon-aminocaproic acid was administered to rats via either intraperitoneal injection or intravenous infusion. Time-response and dose-response studies of the resultant plasma levels of fibrinolytic activity were measured by a modification of a standard fibrin plate technique. The modified technique involved the addition of human plasma to rat plasma in a ratio of 10:1 (rat:human). The plasma levels of fibrinolytic activity reflected plasma concentrations of epsilon-aminocaproic acid.

Aminocaproates↗
PubMed1980

Arteriovenous malformations of the brain. I: Current concepts and treatment.

Arteriovenous malformations (AVMs) of the brain are uncommon congenital lesions, causing symptoms in the middle decades of life. Neurosurgical and neuroradiological techniques have been developed to deal effectively with these lesions, in many instances resulting in a cure. This first part of a two-part article details the important anatomic aspects of these lesions, symptoms, and radiographic considerations. The largest group of lesions discussed here, the AVMs, vary in size but are usually large, involving important areas of the cortex and white matter with a complex array of arterial to venous shunts. Their most common initial symptoms are due to hemorrhage or seizure. The use of the computerized tomographic scan has often resulted in the unexpected diagnosis of these lesions. However, angiography remains the paramount method of defining these lesions.

Brain Neoplasms↗
PubMed1980

Arteriovenous malformations of the brain. II: Current concepts and treatment.

In this second of a two-part article, the treatment of arteriovenous malformations (AVMs) of the brain is discussed. The natural course of these lesions, which is treacherous, must be balanced against the risk-effectiveness of various therapies. Radiotherapy rarely abolishes these lesions and subjects the patient to the risk of radionecrosis and rebleed from the AVM. Embolization, which involves the placement of small spheres into the lesion under radiographic control, is a moderately safe procedure that can reduce the size of, but rarely eliminates, these malformations. Embolization, however, has been used effectively in preparing the lesion for excision. The techniques of contemporary surgery and the results of treatment of a large number of AVMs are discussed.

Cerebral Angiography↗
PubMed1980

Third ventricular tumors.

Because of the uncertainty of a histological diagnosis without biopsy in tumors which lie within the third ventricle, we have advocated a surgical exploration of all cases. Those located in the posterior third ventricular or pineal region present a special problem and have been discussed elsewhere. Tumors lying in anterior portions of the third ventricle have been approached through a transcallosal route which we have preferred over the transfrontal route for the reasons indicated. The approach is relatively simple and associated with low morbidity. Problems have been encountered from forceful retraction of the anterior sagittal sinus which has resulted in deficits of frontal lobe function and with injury to both fornices or the septal region which has resulted in akinetic mutism. Fortunately, these complications are rare.

Adult↗
PubMed1979

Surgical lesions of the intracranial optic nerves and optic chiasm.

Compressive tumors and vascular lesions affecting the intracranial optic nerves and optic chiasm are of interest to both the neurosurgeon and the neuro-ophthalmologist. Common types of tumors that occur in the chiasmal and parasellar regions are discussed in terms of their course, neuro-ophthalmologic implications, and surgical treatment by the transsphenoidal approach as opposed to the standard subfrontal approach. Vascular lesions that cause visual distrubances, including intracranial aneurysms and arteries acting as compressive lesions of the chiasm and nerves or in conjunction with tumors, are discussed.

Aneurysm↗
PubMed1979

Factors governing the course of emboli in the therapeutic embolization of cerebral arteriovenous malformations.

Many factors are involved in the therapeutic intra-arterial management of cerebral arteriovenous malformations (AVMs) by embolization. If these factors could be better defined, the suitability of patients for embolization could be more accurately predicted. In 59 embolization procedures, the diameters of feeding arteries of AVMs were analyzed, and a critical diameter found below which emboli are likely to stray into normal vessels and above which embolization can be carried out with a greater chance of success. Neurologic complications occurred on 20 occasions, but most were temporary; in only 1 of 34 patients did a permanent incapacitating complication occur.

Adult↗
PubMed1979

Meningiomas of the pineal region and third ventricle.

The clinical presentation, radiological findings, and surgical management of two cases of meningioma arising from the velum interpositum without dural attachment are described. The true nature of these tumors was not suspected despite extensive preoperative diagnostic evaluation. A total removal was effected in both cases with the use of the operating microscope and a posterior fossa approach to the pineal region. A review of similar cases from the English literature is presented.

Adult↗
PubMed1979

Supracerebellar-infratentorial approach to pineal tumors.

Utilizing the Krause exposure, we have operated on 21 cases of tumors of the pineal region encountering a wide variety of histology with an overall 30% incidence of benign lesions. There has been no significant morbidity in the post-operative management of these patients and one surgical death in a patient with a highly malignant glioma who developed a delayed hemorrhage into the tumor following the operation. In those tumors of recognized malignancy, post-operative radiotherapy has been utilized. In tumors of the germinoma, variety radiation of the entire neural axis is advocated. Since many of the patients have undergone radiotherapy prior to our exposure of the pineal tumor, we have had an opportunity to witness the effects of radiation on this region. In those cases of benign tumors we have found dense adhesions between the tumor and the brain, making definitive surgical treatment of the tumor more difficult.

Brain Neoplasms↗
PubMed1978

Bipotentiality of response to sex hormones by the prostate of castrated or hypophysectomized dogs. Direct effects of estrogen.

Prostatic response to administered estradiol-17beta 17-cyclopentylpropionate (ECP) was studied in castrated or hypophysectomized dogs. Ultrastructural investigation identified two types of epithelial cells, squamous and modified glandular, that resulted from estrogen action. Squamous cells, which predominated, appeared to evolve from basal reserve cells. Estrogen-modified glandular cells have features attributable to estrogen and previous androgen stimulation. Thaw-mount autoradiography of explants located radiolabeled estrogen in prostatic epithelium and stroma of normal and ECP-treated animals, suggesting a role of estrogen in prostatic homeostasis. Epithelium from ECP-treated dogs incorporated 3H-thymidine, indicating that estrogen promotes DNA synthesis in these cells. Greatly enhanced conversion of radiotestosterone to 4-androstene-3,17-dione, with sharply decreased formation of 5alpha-reduced hydroxylation products, and attendant elevation in estradiol-17beta oxidoreductase activity are metabolic markers attributable to the induced squamous and responding stromal cells. The duality of prostatic response to sex hormones is apparent from observations that estrogen stimulates regressed glandular epithelium which had undergone androgen-mediated differentiation before ablation.

Animals↗