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Biomedical subjects

J A Gutierrez-Diaz

Publications and source records attributed to J A Gutierrez-Diaz.

10 recordsLinked to original sources
PubMed1995

Intraoperative radiation therapy in malignant glioma: early clinical results.

Intraoperative radiation therapy (IORT) with high energy electron beams is a treatment modality that has been included in multimodal programs in oncology to improve local tumor control. From August 1991 to December 1993, 17 patients with primary (8) or recurrent (9) high grade malignant gliomas, anaplastic astrocytoma (4), anaplastic oligodendroglioma (6) and glioblastoma multiforme (7), underwent surgical resection and a single dose of 10-20 Gy intraoperative radiation therapy was delivered in tumor bed. Fourteen patients received either pre-operative (8) or post-operative (6) external beam radiation therapy. Primary gliomas: 18-months actuarial survival rate has been 56% (range: 1-21+ months) and the median survival time has not yet been achieved. Four patients developed tumor progression (median time to tumor progression: 9 months). Recurrent gliomas: 18-months actuarial survival rate and median survival time has been 47% and 13 months (range: 6-32+ months) respectively. The median time to tumor progression was 11 months. No IORT related mortality has been observed. IORT is an attractive, tolerable and feasible treatment modality as antitumoral intensification procedure in high grade malignant gliomas.

Adolescent↗
PubMed1987

Adrenergic innervation of human middle cerebral artery. Ultrastructural observations.

The innervation of the human middle cerebral artery is studied with transmission electron microscopy using the chromaffin reaction technique. Adrenergic nerve fibers and related terminals, with granular electrodense neurotransmitter vesicles, are confined to the tunica adventitia-tunica media transitional zone and the outer layers of the media. These findings may indicate the presence of an adrenergic vasoconstrictor system for circulation control in the human middle cerebral artery.

Cerebral Arteries↗
PubMed1987

Intramembranous cytochemistry: a new morphological technique for studying cholesterol in the astrocyte plasma membrane of ischemic brain cells.

The distribution of cholesterol in the astrocytic plasma membranes of normal and ischemic caudate nucleus in the cat was investigated with the polyene antibiotic, filipin, a morphological probe for membrane cholesterol domains in freeze-fracture tissue replicas. After filipin incubation of prefixed vibratome slices, filipin-cholesterol complexes appeared as 20 to 30 nm protuberances and pits on P- and E-faces of the replicas. Distinct patterns of filipin-cholesterol complexes were found on nonischemic and ischemic astrocyte membranes. The filipin-treated specimens showed an 80% decrease in astroglial plasmalemma of cholesterol 1 hour after cerebral ischemia.

Animals↗
PubMed1985

Quantitative electron microscopic study of calcium accumulation in cerebral ischemia mitochondria.

Formation of calcium deposits in mitochondria is a consistent feature of irreversible injury in ischemic myocardium. We studied calcium accumulation in nerve cell mitochondria in a cat model 30 and 60 minutes after cerebral ischemia localized in the anterior part of the caudate nucleus and adjacent internal capsule. In control animals, calcium deposits were visible in synaptic vesicles, Golgi apparatus, mitochondria, lysosomes, and in glial and neuronal nuclei. After cerebral ischemia, findings included astrocytic swelling and degeneration of neurons, with an increase in calcium pyroantimoniate mitochondrial deposits. Content of intramitochondrial calcium deposits is related to duration of ischemia as well as the amount of cellular lesions.

Animals↗
PubMed1985

Intraluminal thrombus and neointimal hyperplasia after microvascular surgery.

Despite advances in instrumentation, suture materials, and techniques, thrombosis and intimal hyperplasia due to myointimal cell proliferation are still problems in microvascular anastomosis. Platelet factors stimulate smooth-muscle cell proliferation and migration, but little is known about platelet-vessel wall interaction in microvascular surgery. This study evaluates the effect of the disposition of platelet or luminal thrombus, or both, in intimal evolution in autologous venous micrografts interposed in the common carotid artery of 30 rats. Three hours postoperatively, venous graft and suture line endothelium was completely denuded, and the host artery exhibited focal de-endothelialization. Thrombus deposition was observed on suture line and venous graft luminal surfaces, whereas host artery-denuded areas exhibited platelet adhesion. Two weeks postoperatively, intimal thickenings developed in venous graft and suture line, becoming narrower toward the venous graft. The distribution and size of intimal thickening did not change significantly at later observation periods (3-8 months). Intimal thrombus deposition and intimal hyperplasia, appearing in later stages of evolution, show a similar pattern of distribution.

Animals↗
PubMed1984

Pericyte endothelial gap junctions in human cerebral capillaries.

Human cerebral tissue has been ultrastructurally studied and gap junctions have been visualized between endothelial cells and pericytes that permit ion exchange. We propose that the functional interrelationship between endothelium and pericytes may play a role in the alteration of capillary diameter for the control of local cerebral blood flow.

Blood-Brain Barrier↗
PubMed1976

Surgical management of tumours of the pineal region.

Tumours of the pineal region and posterior part of the third ventricle are rare in European and American series (0.5 to 1% of space-occupying lesions). Personal experience is usually limited and thus cooperative studies or critical reviews of reported cases are necessary to establish therapeutic criteria. We have studied 50 cases from our own material of more than 5,000 brain tumours and intracranial space-occupying lesions operated on during the last 30 years. Another 6 verified cases from Dr. F. Isamat, and more than 200 verified tumours from the literature are added. Histological distribution shows that 24% of the tumours in this locality are benign. The different surgical techniques fro reaching the pineal region are reviewed. The results of palliative operations, or partial removals together with radiotherapy, and total removals are presented in 200 verified cases (Table 1), as well as the results obtained by the different surgical approaches (Table 2). Finally, some conclusions are reached regarding the surgical management of these tumours. More than two thirds are radiosensitive, and in about 50 to 70% good results may be obtained with palliative operations and radiotherapy. The remainder of the pineal tumours (about 20%) should be treated by a direct surgical approach. Recent technical improvements and the use of the surgical microscope have reduced the mortality of pineal surgery and allow verification of the histological nature of the tumour in order to establish more rational treatment.

Brain Neoplasms↗