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Biomedical subjects

G Candia

Publications and source records attributed to G Candia.

9 recordsLinked to original sources
PubMed1990

Transsphenoidal surgery for visual loss in patients with pituitary adenomas.

This paper presents the results of transsphenoidal surgery in 41 consecutive patients with visual loss from pituitary adenomas. The most common pattern of loss was bitemporal hemianopia. Transsphenoidal decompression resulted in visual improvement in 78% of patients. If patients with optic atrophy and pre-operative complete blindness were excluded, improvement extended to 94% of patients. Because of its efficacy and low morbidity, transsphenoidal resection of pituitary tumours is the procedure of choice for most adenomas with extrasellar extension and visual field loss.

Adenoma↗
PubMed1989

The calmodulin antagonist trifluoperazine provides mild prophylactic protection against cerebral vasospasm after subarachnoid hemorrhage, but no therapeutic value.

In vitro studies of the canine basilar artery have demonstrated that calmodulin antagonism can effectively inhibit cerebral arterial smooth muscle contractility. The prophylactic and therapeutic effectiveness of a potent calmodulin antagonist, the phenothiazine compound trifluoperazine (TFP), was investigated in vivo over a wide range of doses in the well-documented "double-subarachnoid hemorrhage" canine model of cerebral vasospasm. The compound is perhaps more well-known under its trade name, Stelazine, as a classic antipsychotic drug. The drug demonstrated no therapeutic relief of preexisting chronic cerebral vasospasm at any time during 2 days of systemic administration at any practical dose. At doses far in excess of the normally accepted therapeutic range in humans, a prophylactic regimen reduced the severity of chronic cerebral vasospasm after subarachnoid hemorrhage by approximately 35% compared to untreated dogs.

Animals↗
PubMed1989

Intracerebral arteriovenous malformations: evaluation with selective MR angiography and venography.

Magnetic resonance (MR) angiography and spin-echo methods were used to evaluate intracerebral arteriovenous malformations (AVMs) in 10 patients. Spin-echo images obtained with flow presaturation demonstrated the nidus of the AVM in all cases, but it was difficult to determine feeding vessels. These vessels were directly visualized with three-dimensional MR angiography; their presence could be indirectly determined by means of selective presaturation of individual vessels, which resulted in a marked decrease in signal within the portion of the AVM supplied by that vessel. Vascular supplies from the internal carotid artery and anterior, middle, or posterior cerebral arteries were detected in all cases, but in three large malformations it was not possible to demonstrate small feeding vessels. MR angiograms were also helpful for further defining the nidus. The combination of MR angiographic and spin-echo methods provides information useful for therapeutic planning not provided by either technique alone.

Adult↗
PubMed1988

Management of large pituitary adenomas by transsphenoidal surgery.

We evaluated the ability of transsphenoidal surgery to produce visual improvement, endocrine remission, and complete tumor removal in 113 patients with pituitary adenomas extending beyond the sella turcica. Eighty-one percent of patients with preoperative visual field defects had postoperative improvement, 19% had no change, and none deteriorated significantly. Seventy-nine percent of patients with diminished preoperative visual acuity had postoperative improvement; none deteriorated. Endocrine remission of functioning tumors was achieved in 43% of patients and complete resection by computed tomography scanning was also obtained in 43%. There were no deaths in this series and the major complication was cerebrospinal fluid leak, which occurred in 3% of patients. Comparison with transfrontal surgery suggests that these results are as good as those with transfrontal procedures and that the incidence of serious side effects is considerably lower. Transsphenoidal surgery is safe and effective in the surgical management of large pituitary adenomas.

Adenoma↗
PubMed1988

Isovolemic hemodilution in experimental focal cerebral ischemia. Part 1: Effects on hemodynamics, hemorheology, and intracranial pressure.

A total of 76 splenectomized dogs were entered in a study of the value and effects of isovolemic hemodilution. Of these, seven were not included in the analysis because of technical errors. Of the remaining 69 dogs, 35 were treated with hemodilution; 28 were subjected to a 6-hour period of temporary occlusion of the distal internal carotid artery and the proximal middle cerebral artery, and seven underwent a sham operation only, with arterial manipulation but no occlusion. The other 34 dogs were not subjected to hemodilution; 26 of these underwent temporary arterial occlusion and eight had a sham operation only. In each group the animals were about equally divided into 1) an acute protocol with regional cerebral blood flow measurements by a radioactive microsphere technique and sacrifice at the end of the acute experiment, and 2) a chronic protocol with survival for 1 week to permit daily neurological assessment and final histopathological examination but without blood flow measurements. Isovolemic hemodilution was performed about 1 hour after the arterial occlusion or sham operation and was accomplished by phlebotomy and infusions of low molecular weight dextran to bring the hematocrit to a level of 30% to 32%. This treatment resulted in a very significant reduction in viscosity and fibrinogen levels. The decrease in hematocrit lasted throughout the week in the animals in the chronic protocol. The decrease in viscosity correlated almost linearly with the decrease in hematocrit. There was a slight decrease in systemic arterial pressure with hemodilution but there were no significant changes in central venous pressure or in pulmonary arterial or wedge pressure. There was a slight decrease in cardiac index in both the hemodilution and control groups, which may have been due to the effects of barbiturate anesthesia. There was a slight increase in the measured blood volume in both groups, which was probably artifactual and related to the method of calculation. Intracranial pressure increased significantly with time in all animals subjected to arterial occlusion, but this increase was less severe in the hemodilution group. There was no significant change in intracranial pressure in sham-operated animals, whether hemodiluted or not. The results of cerebral blood flow measurements, assessment of neurological conditions, and measurement of infarct size are given in Part 2 of this report.

Animals↗
PubMed1988

Isovolemic hemodilution in experimental focal cerebral ischemia. Part 2: Effects on regional cerebral blood flow and size of infarction.

Seventy-six splenectomized dogs were entered in a study of the value and effects of isovolemic hemodilution. Of these, seven were not included in the analysis because of technical errors. Of the remaining 69 dogs, 35 were treated with hemodilution; 28 were subjected to a 6-hour period of temporary occlusion of the distal internal carotid artery and the proximal middle cerebral artery, and seven underwent a sham operation only, with arterial manipulation but no occlusion. The other 34 dogs were not subjected to hemodilution; 26 of these underwent temporary arterial occlusion and eight had a sham operation only. In each group the animals were about equally divided into 1) an acute protocol with regional cerebral blood flow measurements by a radioactive microsphere technique and sacrifice at the end of the acute experiment, and 2) a chronic protocol with survival for 1 week to permit daily neurological assessment and final histopathological examination but without blood flow measurements. The general experimental protocol, the hemodynamic and rheological measurements, and the changes in intracranial pressure are described in Part 1 of this report. In the animals with arterial occlusion, blood flow decreased significantly in the territory of the ischemic middle cerebral artery. This decrease was partially reversed by hemodilution in the animals so treated. When the changes in blood flow before and after hemodilution in treated animals are compared with the changes at equivalent times in animals without hemodilution, the increases in flow in the gray matter of the ischemic hemisphere brought about by hemodilution are statistically significant. The neurological condition of the animals in the chronic protocol (sacrificed 1 week after occlusion) with hemodilution, as evaluated by daily neurological assessment, was significantly better than that of the control animals. In the animals sacrificed acutely (8 hours after arterial occlusion), the volume of infarction as estimated by the tetrazolium chloride histochemical method was 7.36% of the total hemispheric volume in the control animals and 1.09% in the hemodiluted animals, showing a statistically significant difference (p less than 0.005). In the chronic animals these values were 9.84% and 1.26%, respectively (p less than 0.005), as calculated by fluorescein staining. By histopathological examination the volume of infarction in the chronic animals was calculated as 10.92% in the control animals and 1.20% in the hemodiluted animals (p less than 0.005).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1979

Reduced incidence of cerebral ischemia following rupture of intracranial aneurysms.

A randomized study was carried out to determine if the administration of reserpine and kanamycin to lower the concentration of vasoactive biogenic monoamines would reduce the incidence of cerebral vascular ischemic complications and death following the rupture of intracranial aneurysms. Twenty-six treated and twenty-eight control (untreated) patients were studied. In the preoperative period, eight control (untreated) patients developed symptomatic cerebral ischemia as opposed to one treated patient. There was no correlation between the preoperative clinical findings of ischemia and angiographic evidence of vasospasm. In the post-operative period four control and one treated patient developed symptomatic cerebral ischemia; vasospasm, as demonstrated by cerebral angiography, paralleled these findings.

Cerebral Infarction↗
PubMedDate not supplied

Intravenous nitroglycerin in experimental cerebral vasospasm. A preliminary report.

Cerebral arteriospasm is a common complication of subarachnoid hemorrhage and is responsible for much of the brain damage which accompanies it. No pharmacologic agent has been found which regularly alleviates arteriospasm. We have evaluated the effect of continuous intravenous nitroglycerin infusion on the diameter of the basilar artery in dogs with cerebral vasospasm experimentally induced by subarachnoid blood injection. In 6 consecutive dogs, 10 minutes after beginning intravenous nitroglycerin at 100 microgram/min and at other times during 120 minutes of infusion, the diameter of the basilar artery had increased from 75 +/- 2% of control value to 114 +/- 2% of control value (p less than 0.001). In all 6 dogs, the basilar artery diameter during infusion was greater than the control value prior to creating subarachnoid hemorrhage. Intravenous nitroglycerin caused only a moderate (8%) decrease in blood pressure. Further investigation of the effects of nitroglycerin on cerebral vasospasm is warranted.

Animals↗