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Biomedical subjects

A N Martins

Publications and source records attributed to A N Martins.

At least 19 recordsLinked to original sources
PubMed1991

Evidence for adrenal medulla involvement in cold adaptation of preoptic-lesioned rats.

The cold-adaptation process was examined in preoptic-lesioned (PO, 18 rats) and adrenaldemedullated-preoptic-lesioned rats (ADPO, 16 rats). PO rats and ADPO female Wistar rats were cold acclimatized to 5 degrees C for 2 operated and then treated exactly like the lesioned rats. Lesions in the PO region caused a decrease in the ability to maintain normal body temperature in a cold environment (5 degrees C for 2 h). Their colonic temperature fell even by the end of the 2nd h of cold exposure (-1.1 degrees C for PO rats and -1.25 degrees C for ADPO rats, P less than 0.01). However, after 2 weeks of cold acclimation the PO rats, but not the ADPO rats were able to thermoregulate in the cold and showed a normal increase in interscapular brown adipose tissue weight (79%, P less than 0.01). These data suggest that the PO is not an essential link for cold adaptation when a mild cold-adaptation method is used. Furthermore, the data show that increased adrenal medullary activity is required for the cold adaptation process in PO rats.

Adaptation, Physiological↗
PubMed1982

Transsphenoidal surgery for prolactin-secreting pituitary tumors: a study of 28 cases and review of the literature.

Twenty-eight patients (22 women, six men) underwent transsphenoidal microsurgery for suspected prolactin-secreting pituitary tumors. Amenorrhea was present in 19 of the 22 women, and galactorrhea, in 21 of the 22 women and two of the six men. Prolactin values preoperatively ranged from 62 to 38,130 ng/ml, and the mean percentage decrease in serum prolactin (PRL) after surgery was 80% (range: 38% to 99%). Twenty patients had microadenomas (tumors less than 10 mm), and seven had macroadenomas (greater than 10 mm). Although no tumor was found in one patient, her serum PRL fell from 65 to 24 ng/ml postoperatively. Surgical results depended upon both the initial PRL level and the tumor size. All eight patients with tumors of less than 10 mm and PRL levels of less than 200 ng/ml had normal postoperative prolactin values, whereas serum PRL returned to normal in only four of eleven patients with microadenomas but with preoperative PRL of greater than 200 ng/ml. None of the five patients with macroadenomas in who serum PRL had been measured preoperatively had normalization of serum PRL postoperatively, including one patient with a preoperative level of less than 200 ng/ml. Menses resumed in 11 of 18 women; galactorrhea improved in six of 11 subjects, and nine pregnancies have occurred. Analysis of these data, as well as those of 12 published series, suggests that both tumor size and the preoperative serum prolactin level are important factors in predicting the success of surgical therapy. Longitudinal follow-up is imperative to determine which patients are truly cured.

Adenoma↗
PubMed1980

Surgically correctable lesions solely detected by CT scan in adult-onset chronic epilepsy.

A prospective study of 162 patients with adult-onset chronic epilepsy revealed 4 in whom computed tomographic scanning was the only diagnostic test that detected the presence of a surgically correctable cerebral lesion. These patients had suffered from seizures for 1 to 14 years and at the time of operation demonstrated no clinical neurological deficits except organic mental changes.

Adult↗
PubMed1979

Experimental delayed radiation necrosis of the brain. Part 1: Effect of early dexamethasone treatment.

The authors have designed an experiment to detect a hitherto unrecognized interaction between high doses of the glucocorticoid, dexamethasone, and brain irradiation. Eighteen juvenile male rhesus monkeys received 1800 rads to the whole brain in 8.5 minutes. For 1 1/2 days before and 10 1/2 days after the irradiation, nine animals received approximately 2.9 mg/kg/day of dexamethasone intramuscularly in addition to irradiation, while the remaining nine animals served as the control group and received saline. All animals eventually developed a progressive neurological syndrome, and died of delayed radiation necrosis of the brain. The two groups were compared with regard to latency to onset of clinical signs, survival time, and number, distribution, and location of lesions of radionecrosis. Large doses of desamethasone did not alter the susceptibility of the primate brain to delayed radiation necrosis. Detailed morphological study of the radionecrotic lesions supports the hypothesis that most, if not all, of the lesions develop as the consequence of injury to blood vessels.

Animals↗
PubMed1978

Double-blind evaluation of chemonucleolysis for herniated lumbar discs. Late results.

Sixty-six patients with symptomatic herniated lumbar discs refractory to the usual conservative management were allocated at random into one of two treatment groups according to a double-blind protocol: 31 received chymopapain intradiscally (chemonucleolysis) and 35 received a placebo intradiscally. Symptoms remained significantly improved 1 year or more after injection for 55% of those treated with chymopapain and for 46% of those treated with placebo. The difference is not statistically significant. However, to discard chemonucleolysis on the basis of this one small clinical trial may be premature. Since continuing controversy has re-established a climate in which another double-blind study of chemonucleolysis is ethically feasible and scientifically desirable, we favor additional clinical trials under a tightly controlled protocol to help resolve the issue.

Adult↗
PubMed1978

Surgically correctable lesions detected by CT in 143 patients with chronic epilepsy.

CT findings justified surgical intervention in four young patients who had suffered from intractable epilepsy for many years. Previous non-invasive and invasive neurodiagnostic procedures with these patients had failed to show focal cerebral lesions amenable to surgical treatment. All four patients achieved significant relief from seizures after the operations.

Adolescent↗
PubMed1977

Sources of error in measuring cerebrospinal fluid formation by ventriculocisternal perfusion.

Ventriculocisternal perfusion is regarded as a precise method of measuring the rate of formation of cerebrospinal fluid (CSF) but it possesses inherent potential sources of error. Using the technique to measure CSF formation rate in the rhesus monkey, we have observed rate changes when none were expected. Most puzzling has been the steady decline of CSF formation rate at 4 percent each hour during the final five hours of a seven hour perfusion although variables known to affect CSF formation remained stable. In addition, alterations in rate caused by artefacts were observed in experiments in which craniospinal blood volume was changed by sudden changes of either PCO2 or central venous pressure. Mobilisation or sequestration of incompletely equilibrated CSF is believed responsible. In other experiments, a small increase of intracranial pressure produced by increasing outflow resistance was quickly followed by an apparent reduction of CSF formation. We have concluded that to assess accurately the effect a variable has on the rate of CSF formation, one must control perfusion time and craniospinal blood volume as well as intracranial pressure.

Animals↗
PubMed1977

Intracanalicular meningioma with normal tomography. Case report.

A middle-aged woman presented with the typical symptoms and signs of a compressive optic nerve lesion. Plain skull films, tomography of the optic canals, and selective angiography with magnification and subtraction were normal. Computerized transaxial tomography clearly showed the tumor, which was a meningioma of the optic nerve sheath. At surgery the tumor was found within the optic canal with intracranial and orbital extensions. It was strictly intradural and did not involve the surrounding bone at any point. This case documents the fact that an intracanalicular meningioma may be associated with normal tomograms of the optic canal.

Adult↗
PubMed1977

Delayed radiation necrosis of the brain.

The cases of six patients are presented to delineate the clinical profile of delayed radiation necrosis of the brain. In five the diagnosis was verified histologically. Symptoms most often begin 9 months to 2 years after radiotherapy. Progressive visual impairment and dementia are common following perisellar irradiation, while hemispheric signs predominate following irradiation of the cerebrum. Cerebrospinal fluid protein may be elevated. Focal delta slowing is usually present on electroencephalography. The necrotic brain may appear on radionuclide brain scan as an area of abnormal uptake and also act as an avascular space-occupying lesion. With computerized tomography, radiation necrosis appears as an intracerebral area with diminished absorption coefficient that is often enhanced with intravenous contrast medium. The syndrome may be sufficiently characteristic to eliminate the need for surgical exploration and biopsy in some cases. Cumulative experience suggests that the risk-to-benefit ratio of radiotherapy becomes increasingly unfavorable for most patients with benign intracranial neoplasms when the standard brain tumor dose of 5000 to 7000 rads is fractionated at greater than 200 rads per day.

Adenoma, Chromophobe↗
PubMed1977

Blood flow and oxygen consumption of the focally traumatized monkey brain.

The exposed left superior frontal gyrus of the anesthetized macaque brain was focally traumatized by a jet of compressed air. Focal blood flow in tissue around the lesion and total cerebral blood flow was determined before and during the 4 hours after trauma by the hydrogen clearance technique. Blood flow fell in tissue adjacent to the injured brain but the reduction was not statistically significant. Total cerebral blood flow, blood flow in the right superior-frontal gyrus, and oxygen consumption of the brain was unaffected by the trauma. The authors conclude that neither spreading ischemia within uninjured tissue surrounding focally traumatized brain nor posttraumatic diaschisis is readily provoked in the anesthetized brain of the monkey.

Animals↗
PubMed1976

PCO(2) and rate of formation of cerebrospinal fluid in the monkey.

Changes in cerebrospinal fluid formation rate (VF) with hypocapnia were measured by the ventriculocisternal perfusion technique in 24 rhesus monkeys anesthetized with nitrous oxide. In addition cerebral blood flow (CBF) was measured by the hydrogen clearence methods, Vf in control animals declined at a mean rate of 2.3 mul/min each hour during the last 4.5 h of a 7-h perfusion although variables known to effect Vf remained stable. Three hours after perfusion began, Vf of normocapnic controls was 41.4 mul/min +/- 5.4; CBF, 59P ML/100 G PER MIN. When Pco(2) was reduced to half of control, Vf fell to 35.6 mul/min +/- 6.3 and CBF fell by 27%. When Pco(2) was doubled, Vf fell to 33.1 mul/min +/- 5.3 and CBF increased threefold. The difference in Vf id significant only for the hypercapnic group (p=0.01). When animals were used as their own controls, three were no significant differences in Vf with hypercapnia compared to normocapnia. These results indicated that in the monkey variations of Pco(2) within broad physiologic limits, which are sufficient to cause large changes in CBF, have little effect of Vf.

Acidosis↗
PubMed1976

Anterior cervical discectomy with and without interbody bone graft.

Fifty-one patients with symptomatic cervical disc disease refractory to conservative management were allocated at random to one of two treatment groups. The standard anterior approach devised by Cloward was used for 25 patients, and radical discectomy and foraminotomy for the other 26. All patients were followed for 6 months or longer with interview, physical examination, and radiographic evaluation. There was no difference in the success rate between the two groups. The large majority (92%) of patients in both groups were pleased with results of their operation. Because of technical factors related to operative exposure of the spinal canal and nerve roots, we prefer the Cloward procedure for patients symptomatic from advanced spondylosis and reserve discectomy without bone graft insertion for those with minimal spondylosis or soft disc herniations.

Adult↗
PubMed1976

Effect of intracisternal phentolamine on cerebral blood flow after subarachnoid injection of blood.

The hydrogen clearance method was used to measure total and focal cerebral blood flow (CBF) in the monkey before and for 5 hours after a simulated subarachnoid hemorrhage (SAH). Some monkeys also received 0.2 to 1.0 mg/kg phentolamine intracisternally 3 hours after SAH. Results show that SAH did not change cerebrovascular resistance, but as cerebral perfusion pressure decreased, CBF fell transiently. Phentolamine injected intracisternally 3 hours after SAH produced a significant fall in arterial blood pressure; cerebrovascular resistance did not change but CBF decreased significantly. These data indicate that intracisternal phentolamine cannot be considered potentially useful to treat ischemic encephalopathy after SAH.

Animals↗
PubMed1976

Double-blind evaluation of intradiscal chymopapain for herniated lumbar discs. Early results.

The authors report 66 patients with signs, symptoms, and a myelographic abnormality of herniated lumbar disc, who were not responsive to conservative treatment. The discs were injected at random with either chymopapain or a placebo. Neither patient nor surgeon knew which agent was used until after the results had been tabulated. Unless early laminectomy was necessary for intractable pain, all patients were followed for 2 months or more. There was no statistically significant difference in incidence or quality of improvement between the two groups: chymopapain was successful in 58% while placebo was successful in 49% (p = 0.15). Early results from this study indicate that most, if not all, of the putative effectiveness of chemonucleolysis probably derives from a placebo effect.

Adult↗
PubMed1975

Acromegaly. Treatment by transsphenoidal microsurgery.

Serum growth hormone levels, thyroid function, and adrenal function were measured before and after surgery in 16 of 17 acromegalic patients undergoing undergoing transnasal transsphenoidal microsurgery of the pituitary. Thirteen patients have been followed up for 12 to 24 months; three patients have been followed up for three to six months. Serum growth hormone levels decreased to less than 5 ng/ml in seven of nine previously untreated patients; thyroid and adrenal function were preserved in eight of these nine patients. In seven patients treated previously by other modes of therapy, growth hormone levels after transsphenoidal surgery decreased to less than 5 ng/ml in three, to between 5 and 10 ng/ml in three, and from 98 to 41 ng/ml in one. Preoperative adrenal function was normal in six of these seven patients and was preserved in four; thyroid function was normal in five patients preoperatively and was preserved in three. Transsphenoidal microsurgery appears to offer an effective means of lowering growth hormone levels and a possiblity of preserving any remaining normal pituitary function. It may be considered for initial treatment in selected patients in whom more rapid arrest of acromegaly is indicated.

Acromegaly↗