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Biomedical subjects

A G May

Publications and source records attributed to A G May.

At least 19 recordsLinked to original sources
PubMed1999

A putative ECF sigma factor gene, rpol, regulates siderophore production in Rhizobium leguminosarum.

A cloned Rhizobium leguminosarum gene, termed rpoI, when transferred to wild-type strains, caused overproduction of the siderophore vicibactin. An rpoI mutant was defective in Fe uptake but was unaffected in symbiotic N2 fixation. The RpoI gene product was similar in sequence to extra-cytoplasmic sigma factors of RNA polymerase. Transcription of rpoI was reduced in cells grown in medium that was replete with Fe.

Amino Acid Sequence↗
PubMed1986

Spinal cord ischemia following operations on the abdominal aorta.

Spinal cord ischemia following operations on the abdominal aorta is considered an unpredictable event attributable to variations in spinal cord blood supply. Our experience with seven cases of spinal cord ischemia contradicts this hypothesis. All patients had a bifurcation graft implanted. Three patients had bilateral interruption of hypogastric circulation. Each had gluteal necrosis and two had left colon ischemia. Two patients had unilateral hypogastric ligation. In both of these patients, early postoperative hypotension preceded recognition of spinal cord ischemia. Two patients without known interruption of hypogastric flow had proximal side-to-end anastomoses placed in an atheromatous aorta. Intraoperative peripheral emboli occurred in one and postoperative visceral emboli occurred in the other patient. In the latter case spinal cord ischemia occurred late concomitantly with embolization. The surmised important details in patients' courses with spinal cord ischemia are (1) interference with pelvic blood flow (five of seven patients) severe enough in three cases to cause gluteal necrosis and (2) a high incidence of perioperative complications. Interruption of an anomalous spinal artery was probably not a factor as cord lesions were mostly distal and no case of spinal cord ischemia occurred after a cylinder graft was placed. Spinal cord ischemia is potentially preventable. Our experience reemphasizes the importance of hypogastric perfusion, the dangers of handling the atheromatous aorta, and the necessity for avoiding postoperative hypotension.

Aged↗
PubMed1986

Carotid endarterectomy in the elderly patient.

Although the segment of the population at the highest risk for cerebral ischemic events is more than 75 years old, there has been hesitancy in performing carotid revascularization in these patients because of an increased risk of perioperative morbidity. Over a period of 54 months, 77 (16 per cent) of 470 carotid endarterectomies performed were upon patients more than 75 years old. There were no differences between age groups with respect to perioperative morbidity or mortality, with three strokes (3.9 per cent) and no deaths in the patients more than 75 years old and 12 strokes (3.1 per cent) and two deaths (0.5 per cent) in the patients less than 75 years old. Postoperative follow-up study ranged from 30 days to five years (a mean of 25 months) in elderly patients. The over-all three and five year survival rate was 78 and 60 per cent, respectively. No patient experienced a stroke during follow-up study. Recurrent symptoms developed in 18 per cent of the elderly patients at three years of follow-up study, and the occurrence was dependent upon the preoperative symptom category (hemispheric 10 per cent and nonhemispheric 33 per cent). We conclude that the low perioperative morbidity and mortality, and subsequent results of carotid endarterectomy in the elderly patient justify operative intervention when significant lesions are encountered.

Actuarial Analysis↗
PubMed1984

Parathyroid hyperplasia and carcinoma within one gland.

A 47-year-old Scottish woman vacationing in the United States presented with a serum calcium level greater than 20 mg/dl and a parathyroid hormone level 16 times greater than normal after a one-week history of severe vomiting and unrelenting abdominal pain. Surgical exploration of the thymus revealed the very rare association of a large (7 by 4 by 0.8 cm) parathyroid carcinoma adjacent to apparently normal parathyroid tissue, separated by a thin fibrous band. Two other hyperplastic and one normal parathyroid glands were also identified. Postoperatively, the patient became hypocalcemic and, for the past nine months, has received maintenance 1-alpha-hydroxycholecalciferol therapy (1 microgram per day) with normal calcium and barely detectable parathyroid hormone levels.

Carcinoma↗
PubMed1984

HLA DR typing of aspirin sensitive asthmatics.

Previous studies have suggested associations of HLA, A, B and C loci antigens with specific subgroups of asthma. We applied DR antigen typing to the aspirin sensitive subgroup to look for similar correlations. Our results show no statistically significant increase in any known DR antigen nor any correlation with A or B locus typing. We did find a non-statistically significant increase in the number of subjects with blank typing at the DR locus, (i.e., a presently unidentified antigen), raising the question of whether a correlation may exist with an as yet undefined antigen.

Aspirin↗
PubMed1984

Carotid endarterectomy for nonhemispheric symptoms: predictors of success.

Over a 4-year period 335 patients underwent 402 carotid endarterectomies: 227 (56%) for carotid territory symptoms, 107 (27%) for nonhemispheric symptoms, and 68 (17%) for asymptomatic lesions. In 317 four-vessel arteriograms, proximal subclavian and/or vertebral lesions were found more frequently in the nonhemispheric group (80 of 97, or 82%) than in the carotid territory group (110 of 220, or 50%; p less than 0.05). EEG changes after carotid clamping occurred more often in the nonhemispheric group (15 of 65, or 23%) than in the carotid territory group (16 of 140, or 11%; p less than 0.001). The perioperative stroke rate was independent of whether nonhemispheric or carotid territory symptoms were present preoperatively (2.8% vs. 3.5%). Follow-up ranged from 1 month to 4 years. Carotid endarterectomy was successful in ameliorating symptoms in patients meeting the criteria for "classic" vertebrobasilar insufficiency more often than in patients not meeting these criteria (73% vs 43% asymptomatic at 24 months). Carotid endarterectomy was successful in patients with carotid stenoses of greater than 60% diameter reduction more often than in patients with smaller stenoses (77% vs. 36% asymptomatic at 24 months). Carotid endarterectomy appears justified in patients with nonhemispheric symptoms when classic vertebrobasilar insufficiency and/or hemodynamically significant carotid stenoses are present.

Aged↗
PubMed1984

Abdominal aortic aneurysm: the case for elective resection.

Abdominal aortic aneurysms are one of the more common problems faced by the vascular surgeon. A review of 898 aneurysms resected at the University of Rochester from 1955 to 1982 revealed a sequential decrease in mortality for elective surgery from 13% in 1955 to 1965, to 8.4% from 1966 to 1973, and 5.6% in the last 8 years. Mortality for resection of ruptured aneurysms remained high (70%). The incidence of ruptured aneurysms has not changed significantly in the last 16 years. For 1980 and 1981 we calculated the hospital costs of surgical treatment of abdominal aortic aneurysms. The mean total cost after elective resection was +10,114 compared with +18,223 after rupture. Increased costs after rupture reflected both a longer stay and more intensive and expensive medical care. Using discharge data from U.S. hospitals in 1979, we extrapolated our cost and mortality data to a national level. Assuming a mortality rate for elective resection of 5% and a mortality rate for resection after rupture of 50%, we estimated that in 1979 +50 million and over 2000 lives could have been saved if patients with abdominal aortic aneurysms had been identified and subjected to elective resection. The incidence of ruptured abdominal aortic aneurysms remains unacceptably high. Mortality from this disease can best be reduced by increased physician awareness and prompt surgical referral.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta, Abdominal↗
PubMed1983

Management of acute ischemia of the upper extremity.

Records of 76 patients who presented with ischemia of the upper extremity from 1966 to 1981 were reviewed. Patients were divided into three groups according to cause: Group 1, emboli from the artery; Group 2, ischemia after catheter injury; and Group 3, ischemia due to lesions of the axillary and subclavian arteries. Management varied among the three groups. Long-term anticoagulation therapy was helpful in Group 1 patients in preventing reembolization. Forty percent of patients with catheter-related trauma required angioplasty of some sort in addition to embolectomy. Management of Group 3 patients was most difficult and the results least acceptable (three patients required amputation). Management of this type of ischemia must be individualized; it should vary according to the underlying disorder.

Acute Disease↗
PubMed1981

Clinical study of pheochromocytoma.

Seventeen patients underwent 22 operations for pheochromocytoma over a 26 year period. The patients included 11 in three kindreds of familial pheochromocytoma and 6 with sporadic tumors. The diagnosis was usually suggested by the patient's history. Confirmation of the diagnosis frequently required repeated testing for urinary or plasma catecholamines. Arteriography was the most effective method of preoperative tumor localization. Two tumors were proven nonfunctional. Others secreted either norepinephrine or epinephrine and norepinephrine. The familial patients showed a high incidence of multiple, bilateral and extraadrenal lesions. In contrast to previous reports, the familial tumors were found more often in the right than in the left adrenal gland. HL-A genotyping analysis of the sporadic and familial patients failed to demonstrate any HL-A antigen association or interdependent segregation of tumor and HL-A antigens within kindreds.

Adolescent↗
PubMed1981

Surgical treatment of occlusive subclavian artery disease.

Thirty-eight patients underwent operations for subclavian artery stenosis over a 12-year period. Nineteen patients had neurologic symptoms and 12 had claudication or ischemia. The classic subclavian steal syndrome was rare. Twenty patients underwent carotid subclavian bypass and 14 underwent subclavian endarterectomy using a cervical or thoracic approach. Follow-up data were available in 35 of 38 patients (average follow-up 36 months). Thirteen of the 14 patients who underwent endarterectomy remained asymptomatic and showed no evidence of restenosis (average follow-up 53 months). Of the 20 patients who had carotid subclavian bypass, Dacron was the graft material used in eight patients and autogenous saphenous vein was used in 12. Thrombosis occurred in five of 12 saphenous vein grafts, two immediately after operation, one at 2 months and two at 10 months. An anastomotic stenosis was identified and corrected in one patient 38 months postoperatively. Recurrent or persistence of symptoms was directly related to graft failure. Thrombosis or stenosis did not occur in any of the Dacron grafts. All patients had some relief of symptoms. Subclavian endarterectomy or carotid subclavian bypass with Dacron gave excellent long-term results. Autogenous saphenous vein were unsatisfactory for these short bypasses.

Adult↗
PubMed1980

Heterozygous C2-deficiency and myasthenia gravis.

Complement deficiency states in myasthenia gravis (MG) have not been reported previously. We describe a 19-year-old woman with typical MG and heterozygous C2 deficiency, along with HLA typing of the patient and her immediate family.

Acetylcholine↗
PubMed1980

Asymptomatic contralateral carotid artery stenosis: a five-year follow-up study following carotid endarterectomy.

Exactly 5 years after carotid endarterectomy for transient ischemic attacks (TIAs), the neurologic status of each of 67 patients whose angiograms demonstrated a contralateral carotid artery, two of which were fatal. One of these patients suffered antecedent TIAs. Two of the 50 patients (4%) without contralateral carotid stenosis experienced symptoms referable to the contralateral carotid; one of the 50 (2%) suffered a CVA without antecedent TIAs; and one of the 50 (2%) experienced a single TIA. Patients with a demonstrable contralateral carotid stenosis were at greater risk of developing contralateral symptoms than those without a stenosis [14 of the 67 versus two of the 50 (P < 0.01)]. There was no correlation between the incidence of new symptoms and the degree of contralateral stenosis. The 3% (two of the 67) incidence of stroke without antecedent TIAs on follow-up in those patients with a contralateral carotid stenosis suggests the following guideline: patients with contralateral carotid stenosis suggests the following guideline: patients with contralateral carotid artery stenosis can be advised to undergo staged carotid endarterectomies if the surgeon's stroke and morbidity rate is less than 3%.

Arterial Occlusive Diseases↗
PubMed1979

Bilateral internal carotid artery aneurysms.

Two patients were treated for bilateral internal carotid artery aneurysms. One had resection and restoration of continuity on the right side nine years after ligation of the left internal carotid artery. The second had sequential resection and reconstruction of both vessels. Complications of carotid aneurysms include embolization, rupture, and thrombosis. Preferred treatment is resection with reconstitution of the flow. Patients with carotid aneurysms should be investigated for similar lesions on the opposite side. Patients who have had one carotid aneurysm treated should be followed up for the possible occurrence of a contralateral aneurysm.

Adult↗
PubMed1979

Renal artery aneurysm.

More and more renal artery aneurysms are being diagnosed, especially after the introduction of selective arteriography for the evaluation of renovascular hypertension. However, renal artery aneurysm still remains a rare entity. The pathogenesis of renal artery aneurysm is identical to the pathogenesis of arterial aneurysm in other arteries. Symptoms of aneurysm of the renal artery are dependent on a variety of factors, the most important of which are the size of the aneurysm, its location, and whether or not rupture has occurred. The indication for operation on renal artery aneurysm is rupture or threat of rupture. Herein we present a review of the literature and a report of 2 cases which exemplify the capabilities of the surgeon in dealing with such cases.

Adult↗