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Biomedical subjects

F G Diaz

Publications and source records attributed to F G Diaz.

At least 145 records · Page 8Linked to original sources
PubMed1982

Histological structural abnormalities of superficial temporal arteries used for extracranial-intracranial anastomosis.

Histological evaluation of the superficial temporal artery resected at the time of extracranial-intracranial anastomosis was performed in 64 consecutive patients. A neuropathologist who was not aware of the medical condition of these patients studied all specimens under light microscopy with hemotoxylin and eosin, Verhoff, and Mallory strains. Intimal proliferation was observed in 62 samples, intimal fibrosis in 56, fragmentation of the internal elastic lamina in 45, splitting of the internal elastic lamina in 41, fragmentation of the media in 38, and fragmentation of the minimal external elastic tissue in 17. Stenosis of the vessel was observed, and graded from 0% to 50%, with a mean of 20%. The development of intraluminal stenosis was considered to be secondary to the development of intimal fibrosis and hyperplasia. The changes observed were progressive and conformed with those previously described; there was no evidence of correlation with sex, diabetes, or hypertension. The implications for the development of occlusion of the anastomosis or stroke, and for patient survival are discussed.

Adolescent↗
PubMed1982

Early angiographic changes after carotid endarterectomy.

This report reviews the angiographic evaluation of 41 patients who underwent a carotid endarterectomy at Henry Ford Hospital. Postoperative angiograms were performed after 48 endarterectomies. Changes included the development of postoperative intimal flaps, common carotid stenosis, carotid occlusions, areas of corrugation, surface irregularities, and postendarterectomy dilatation. The development of dilatation, or the pantaloon effect, on the endarterectomized segment contributed to the limited use of angioplastic procedures. The benefits derived from a postoperative angiogram include the objective evaluation of the endarterectomized segment, the demonstration of a potentially complicating problem such as intimal flaps that could lead to restenosis, and recognition of the possible development of associated local problems. The procedure can be done with limited risks to the patients and in competent hands has low morbidity and mortality.

Adult↗
PubMed1981

Acute cerebral revascularization: Part 3. Cerebral blood flow.

The efficacy of cerebral revascularization by a superficial temporal-middle cerebral artery anastomosis done 4 and 24 hours following combined occlusion of the middle cerebral and internal carotid arteries (MCA/ICA) was tested in 15 dogs. An untreated and a sham-operated group of 8 and 5 dogs, respectively, controlled possible intercurrent variables. Regional cerebral blood flow (rCBF) was measured by the hydrogen clearance method. Values of normal and preocclusion blood flow under basal conditions and following inhalation of 5% CO2 were similar to values reported by other researchers. Combined MCA/ICA occlusion produced a significant drop in rCBF in the ipsilateral hemisphere (p less than 0.01). The rCBF returned to normal following revascularization in 4 and 24 hours, and after the sham procedure. The rCBF response to inhalation of 5% CO2 was normal in the revascularized group, but was reversed (p less than 0.01) in the sham group. The reversal of flow in the sham group suggested that loss of cerebral autoregulation and steal of blood flow in the infarcted area occurred.

Animals↗
PubMed1981

Agents for cerebral edema.

Hyperventilation, ventricular drainage, and mannitol remain the mainstays of the treatment of cerebral edema not amenable to or following surgical therapy. There appears to be good therapeutic rationale for the use of "low-dose" mannitol in more prolonged treatment of intracranial hypertension (Table 5.1). The beneficial effects of steroids, either in "standard" or "high" doses, is less clear but, pending evidence to the contrary, we favor the use of "high-dose" corticosteroid therapy. Barbiturates appear to hold promise, but pending controlled, randomized trials to confirm or refute their efficacy, the logistics of their use, as well as their potential complications, precludes their widespread use outside of major centers. Certainly, the "ideal" agent for the treatment of cerebral edema, one that would selectively mobilize and/or prevent the formation of edema fluid with a rapid onset and prolonged duration of action, and with minimal side effects, remains to be discovered. In the meantime, research to refine the use of the older agents and determine the usefulness of the newer ones should be encouraged.

Acetazolamide↗
PubMed1981

Silent duodenal perforation. A difficult diagnosis in iatrogenic barbiturate coma.

Iatrogenic barbiturate coma for the control of intracranial hypertension is a relatively new addition to the neurosurgeon's therapeutic armamentarium. Although initial studies are quite promising, the induction of coma, especially for prolonged periods (ranging from days to weeks), is a major therapeutic endeavor which requires sophisticated monitoring of both neurological and physiological function. A multidisciplinary approach prevents many possible complications of this form of therapy and facilitates treatment when untoward physiological complications do occur. The following case report illustrates one such complication.

Accidents, Traffic↗
PubMed1980

Experimental cerebral ischemia.

The basic concepts of the pathology and pathophysiology of cerebral ischemia are presented. Special emphasis is given to the changes that occur in the microcirculation and in autoregulation because of their primary role in the pathogenesis of cerebral infarction. The effects of adrenal steroids, barbiturates, and cerebral revascularization are reviewed.

Animals↗
PubMed1979

Early diagnosis of delayed posttraumatic intracerebral hematomas.

Nine cases of delayed posttraumatic intracerebral hematomas (DTICH) were found retrospectively among 656 patients with closed head injuries admitted to the Hennepin County Medical Center in a 12-month period. All cases had severe head injuries sustained with the head in motion. The interval from cranial injury to diagnosis of DTICH by computerized tomography (CT) varied from 8 hours to 13 days. Eight patients were comatose on admission, three had focal seizures, and three had focal findings. The diagnosis was made on repeat CT scans obtained because of the development of focal findings in four cases, lack of improvement in four cases, and general neurological deterioration in one case. Four patients had initially negative CT scans. Four demonstrated only extracerebral hematomas on initial CT scan. One patient showed intracerebral hematoma on the initial scan followed by new hematomas on repeat study. The cases presented are discussed in light of pertinent literature.

Accidents, Traffic↗
PubMed1979

Acute cerebral revascularization after regional cerebral ischemia in the dog. Part 2: Clinicopathological correlation.

The efficacy of cerebral revascularization by anastomosis of the superficial temporal artery (STA) to the middle cerebral artery (MCA), performed 4 and 24 hours after a regional MCA infarction had been produced by combined occlusion of the MCA and internal carotid artery, was tested in 12 dogs. To control possible intercurrent variables, seven other dogs remained untreated and five had a sham operation. Clinical and pathological changes were recorded and analyzed. An incidence of 85% infarction was obtained in the untreated control group. The severity of the clinical deficits and pathological changes for the anastomosed groups were greater than those seen in the untreated control group. The extent of the infarction was significantly greater (p less than 0.05) in the anastomosed groups than in the sham-operated and control groups. Hemorrhagic infarcts occurred in most of the dogs in the anastomosed groups, but were not present in either control group (p less than 0.05). Two dogs in the 4-hour and one in the 24-hour group improved more than any control dog, but the difference was not statistically significant (p greater than 0.05). In two dogs with occluded anastomosis the clinical deficits and the pathological changes were less than those seen in animals with patent anastomosis. The severity of the pathological and clinical changes correlated well with the reestablishment of flow in the MCA territory. It is proposed that cerebral revascularization at 4 and 24 hours following a regional MCA infarct in the dog is followed by an exacerbation of the microcirculatory obstruction, cerebral edema, and infarction. From improvement noted in three animals the authors suggest that under special conditions the revascularization could benefit some cases following acute cerebral infarction.

Animals↗
PubMed1979

Acute cerebral revascularization: part I. Cerebral ischemia experimental animal model.

Thirty-two mongrel dogs divided into two groups were subjected to a transorbital occlusion of the middle cerebral artery (MCA) or a combined transorbital MCA and cervical internal carotid artery (ICA) occlusion. Clinically apparent deficits were present in the MCA group in 18% of cases and in 73% of MCA/ICA cases. Pathologically, 55% of MCA cases and 73% of MCA/ICA cases had demonstrable areas of infarction. The incidence and severity of clinical deficits as well as the location and extent of pathological infarction were significantly greater (p less than 0.05) with the MCA/ICA group than in the MCA group. The mortality rate and frequency of pathologically apparent infarcts were not statistically different p greater than 0.05. No hemorrhagic infarctions were seen in any case.

Animals↗
PubMedDate not supplied

Comparison of neural precursor cell fate in second trimester human brain and spinal cord.

Neural transplantation holds promise for the treatment of traumatic brain and spinal cord injury by replacing lost cellular elements as well as repairing neural damage. Fetal human stem cells derived from central nervous system (CNS) tissue are potential transplantable sources for all cell types found in the mature human nervous system including neurons, astrocytes and oligodendroglia. Although nearly all areas of the fetal human neuraxis contain undifferentiated neural precursor cells, the phenotypic fate of the daughter cells might vary from one region to another during a specific developmental period. The purpose of this study was to compare the various cell types derived from neural precursors cultured from second trimester fetal human brain and spinal cord. To this end, brains (n = 8) and spinal cords (n = 8) of 15-24 week fetuses were dissociated and grown in culture medium supplemented with epidermal growth factor (EGF), basic fibroblast growth factor (FGF) and leukemia inhibitory factor (LIF). The proliferating precursor cells from both brain and spinal cord grew as spherical masses that were plated on laminin-coated dishes after seven days in culture. During the next 5-7 days, the cells that emerged from these spheres were fixed and processed for immunocytochemistry. Brain derived spheres gave rise to cells expressing antigens specific for neurons (MAP-2ab and neuron specific-intermediate filaments), astrocytes (GFAP) and oligodendrocytes (A007). In contrast, cells that emerged from spinal cord derived spheres were only immunoreactive for GFAP. These data suggest that neuroepithelial precursor cells from different CNS regions, although similar in their responsiveness to proliferative growth factors, might differ in their ability to generate different cell types in the adult CNS.

Astrocytes↗
PubMedDate not supplied

Biomechanical properties of calvarium prosthesis.

There are many materials available for the reconstruction of calvarial defects. Even though their biomaterial properties are well known, the biomechanical properties as part of the calvarium have not been investigated. In this article, calvarial implants are reviewed with their historic development into modern cranioplasty. Materials for trephined skulls are classified by their category. Individual parameters to describe their mechanical properties are collected and revealed in detail. The laboratory testing methodology for cranioplasty material is introduced to understand each parameter. At last, we discuss an engineering technique to look into the implant behavior. Since there is no standard goal for the biomechanical and biomaterial point of view for cranioplasty, this article suggests the finite element method for evaluation of the implant behavior and the degree of damage upon the impact injury.

Biomechanical Phenomena↗
PubMedDate not supplied

Vascular injury in neurotrauma.

Traumatic vascular lesions can occur after severe or even the most mild of head and cervical trauma. The initial evaluation of the injured patient must be thorough and the clinical suspicion of vascular injury must be highly suspected based on the mechanism of injury. Traumatic vascular injuries can be broadly classified into traumatic aneurysms, dissections and occlusions and fistulae of the carotid or vertebral arteries. The current management and treatment options of each condition are discussed.

Brain Injuries↗
PubMedDate not supplied

Neural and vascular tissue reaction to aneurysm-coating adhesive (ethyl 2-cyanoacrylate).

The effect of ethyl 2-cyanoacrylate (Aaron-2-Alpha) obtained from two different manufactures was evaluated in 37 cats divided into two groups. The first group (n = 28) received a 9-year-old preparation. The second group (n = 9) received recently acquired adhesive. Aaron-2-Alpha was applied to the left cruciate cortex and left femoral neurovascular bundle under barbiturate anesthesia. Normal saline was applied on the right side for control. Survival was allowed for 2, 4, 7, and 14 days after application of the adhesive. The 2-day survival was excluded in the second group. Neuropathological examination revealed meningeal necrosis, neuronal and axonal degeneration, vascular wall degeneration, thrombosis, and inflammatory reaction in both groups of cats. The compounds tested are far from satisfying the ideal requirements for their safe use. Chemical degradation may take place in the adhesives stored for prolonged periods of time. Adhesives obtained from two different sources may contain adjuvants of different toxicity. Severe local tissue reaction could produce marked neurological deficits when adhesives are applied in critical areas.

Animals↗