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Biomedical subjects

J H Thomas

Publications and source records attributed to J H Thomas.

At least 127 records · Page 7Linked to original sources
PubMed1986

Comparative studies of computerized tomography and mediastinoscopy for the staging of bronchogenic carcinoma.

The accuracy of mediastinal computerized tomographic scans for the staging of bronchogenic carcinoma varies between institutions. In the present study, the sensitivity rate was 57 percent, the specificity rate 69 percent, and the overall accuracy rate 64 percent, all of which were generally lower than rates reported in the recent literature. Different scanning equipment, diagnostic criteria, and patient populations may all contribute to this variance. The data in this report suggest that tumor histologic type and location also influenced the accuracy of computerized tomography. On the basis of this study and review of the literature, it is recommended that any given institution assess the accuracy of its own computerized tomographic mediastinal scans before substituting scanning for mediastinoscopy in the preoperative staging of bronchogenic carcinoma.

Adult↗
PubMed1986

Post-thyroidectomy hypocalcemia. Incidence and risk factors.

Two hundred twenty-one patients undergoing thyroidectomy were analyzed for factors increasing the risk of postoperative hypocalcemia. Eighty-three percent of all patients experienced hypocalcemia postoperatively, with 13 percent requiring some treatment for symptoms. Patients with advanced thyroid cancer, Graves' disease, or other manifestations of preoperative hyperthyroidism had significantly increased rates of hypocalcemia compared with patients with small cancers or benign euthyroid disease. Total thyroidectomy, repeat thyroidectomy, and thyroidectomy plus neck dissection all significantly increased the incidence of permanent hypocalcemia, whereas lobectomy or subtotal thyroidectomy for benign euthyroid disease were low risk operations. Inadvertent excision of more than one parathyroid gland during thyroidectomy also significantly increased the rate of permanent hypocalcemia.

Adolescent↗
PubMed1985

The effect of streptozotocin diabetes on insulin binding by isolated rat kidney tubules.

Preparations of kidney tubules were isolated from rat kidney cortex and were demonstrated to possess specific binding sites for insulin. The binding was time-and temperature-dependent and the label was displaced by bovine insulin, A1-B29 dodecoyl insulin, proinsulin and insulin A- and B-chains in proportion to their relative activity. Cell-associated degradation was studied by incubating tubules in the presence of fatty-acid-free albumin. The tubules showed high insulin-degrading activity, which was dependent on temperature, time and cell concentration. The number and affinity of insulin receptors on tubules isolated from kidneys taken from streptozotocin-diabetic rats was not significantly different from tubules isolated from untreated control or insulin-treated diabetic rats. Diabetes did not alter the kinetics of insulin degradation by the tubules. This lack of response by the tubules to changes in the concentration of circulating insulin supports the hypothesis that the kidneys do not play an active role in modulating the rate of insulin removal from the circulation.

Animals↗
PubMed1985

Therapeutic alternatives in patients with esophageal cancer.

The records of 52 patients treated either with surgery alone (Group A), preoperative radiotherapy (Group B), or combined preoperative chemotherapy and radiotherapy (Group C) were reviewed to determine the optimal management of patients with squamous cell carcinoma of the esophagus. There was a significant difference in the number of patients with stage III disease between Groups A and C (100 percent and 48 percent, respectively). With the decrease in patients with stage III disease, both resectability rates in Groups A and C (21 percent and 62 percent) and 2 year cumulative survival (0 and 52 percent) increased. Eleven patients in Group C (53 percent) had apparent total resolution of the primary tumor after preoperative therapy. Microscopic tumor was present but was not detected by repeat endoscopy in 35 percent of these patients. The survival rate was higher in patients with apparent total tumor regression who underwent esophageal resection. These results suggest that patients with squamous cell carcinoma of the esophagus are best treated with preoperative chemotherapy and radiotherapy followed by esophagectomy regardless of their response to preoperative therapy.

Adult↗
PubMed1985

Success of profundoplasty: the role of the extent of deep femoral artery disease.

A review of 64 profundoplasties performed in conjunction with inflow procedures for multilevel vascular occlusive disease of the lower extremity revealed that the extent of deep femoral artery disease had a strong influence on results. Profundoplasty for proximal deep femoral artery disease resulted in an 80 percent success rate when carried out for claudication, and an approximately 65 percent success rate for limb salvage and in limbs with poor runoff. In contrast, profundoplasty for diffuse or distal deep femoral artery diseases resulted in a 62 percent success rate for claudication and decreased to approximately 20 percent for limb salvage or in extremities with poor runoff.

Adult↗
PubMed1985

Ultrasonographic and angiographic evaluation of polytetrafluoroethylene aortic bifurcation grafts.

Arterial reconstruction in 50 consecutive male patients with aortoiliac aneurysmal or occlusive disease was performed with PTFE bifurcation grafts. Follow-up intervals ranged from 1 to 39 months. All patients were evaluated by physical examination at 19.5 +/- 1.3 months. In addition, 46 patients were evaluated by ultrasonography at 18.2 +/- 1.2 months, 19 by angiography at 19.8 +/- 2.2 months, and 4 by computerized axial tomography at 21.5 +/- 5.2 months. Intraluminal thrombus or pannus was found in one graft in a patient with compromised outflow, but all graft limbs were patent. There were no accumulations of perigraft fluid, graft dilatations, or anastomotic aneurysms. The results of this study provide support for the continued use of PTFE bifurcation grafts for aortic reconstruction.

Aneurysm↗
PubMed1985

Isolation and characterization of mutations in the beta-tubulin gene of Saccharomyces cerevisiae.

Of 173 mutants of Saccharomyces cerevisiae resistant to the antimitotic drug benomyl (BenR), six also conferred cold-sensitivity for growth and three others conferred temperature-sensitivity for growth in the absence of benomyl. All of the benR mutations tested, including the nine conditional-lethal mutations, were shown to be in the same gene. This gene, TUB2, has previously been molecularly cloned and identified as the yeast structural gene encoding beta-tubulin. Four of the conditional-lethal alleles of TUB2 were mapped to particular restriction fragments within the gene. One of these mutations was cloned and sequenced, revealing a single amino acid change, from arginine to histidine at amino acid position 241, which is responsible for both the BenR and the cold-sensitive lethal phenotypes. The terminal arrest morphology of conditional-lethal alleles of TUB2 at their restrictive temperature showed a characteristic cell-division-cycle defect, suggesting a requirement for tubulin function primarily in mitosis during the vegetative growth cycle. The TUB2 gene was genetically mapped to the distal left arm of chromosome VI, very near the actin gene, ACT1; no CDC (cell-division-cycle) loci have been mapped previously to this location. TUB2 is thus the first cell-division-cycle gene known to encode a cytoskeletal protein that has been identified in S. cerevisiae.

Alleles↗
PubMed1985

A study of the techniques of cardiac massage with the abdomen open.

The present study compares the hemodynamic effectiveness of closed-chest cardiac massage (CCCM) with closed subdiaphragmatic massage (CSDM) and four open transdiaphragmatic cardiac massage techniques during cardiac arrest with an open abdomen. In 10 dogs CCCM resulted in the lowest cardiac index (CI), mean arterial pressure (MBP), and carotid blood flow (CBF) of all cardiac massage techniques tested. CSDM was not statistically superior to CCCM in the dog (p greater than 0.05) but did result in a 23% increase in CI and a 54% increase in CBF. Transdiaphragmatic retrocardiac massage through an incision in the diaphragm resulted in the highest CI, MBP, and CBF of all the four open transdiaphragmatic techniques and had significantly higher values than those for CCCM in the dog (p less than 0.05). In three cadaveric renal donors, all four open transdiaphragmatic techniques and CSDM were noted to be equal to or superior to CCCM. Three patients have been successfully resuscitated with diaphragmatic cardiac massage techniques for cardiac arrest while undergoing abdominal operations. These studies reveal that all subdiaphragmatic or transdiaphragmatic techniques for cardiac massage are hemodynamically equivalent to or superior to the standard CCCM without such complications as fractured ribs and should be considered the treatment of choice for cardiac arrest in the patient with an open abdomen.

Abdomen↗
PubMed1984

Effect of biliary decompression on morbidity and mortality of pancreatoduodenectomy.

To evaluate the effect of levels of serum bilirubin on morbidity and mortality after pancreatoduodenectomy, a prospective study was designed to compare patients who underwent preoperative biliary decompression to those who did not. Preoperative biliary decompression decreased the mean serum bilirubin level from 15.8 to 5.8 mg/dl in one group of 10 patients (Group A). The only statistical differences between this group and the two other groups of patients (Groups B and C) who were not treated with preoperative biliary decompression was the level of serum bilirubin before pancreatoduodenectomy (5.8, 22, and 1.3 mg/dl in Groups A, B, and C, respectively). Only one death occurred in each group of patients. The numbers of nonfatal complications were comparable. These results suggest that there is no decrease in morbidity or mortality after pancreatoduodenectomy when the serum bilirubin level is decreased by preoperative biliary drainage.

Aged↗
PubMed1984

Incidence of recurrent stenosis after carotid endarterectomy determined by digital subtraction angiography.

The results of recent reports of nonselected patients studied by noninvasive techniques suggest there is a 10 to 36 percent rate of restenosis within the first 1 to 2 years after carotid endarterectomy. In the present study of nonselected patients examined by intravenous digital subtraction angiography, only 6.7 percent of operated vessels had recurrent stenosis with a 50 percent or greater decrease in vessel diameter at a mean of 28.5 months postoperatively. These data, when compared with the results of most noninvasive studies, suggest that many of the early lesions regress after 1 to 2 years, as suggested by Zierler et al [8] or that there is a true difference in the rates of restenosis between centers, possibly due to subtle differences in surgical technique or patient risk factors, or both. A symptomatic recurrence rate of only 2.7 percent and a 6.7 percent overall rate of hemodynamically significant recurrent stenosis support the conclusions from earlier and larger series that carotid endarterectomy is a highly effective and durable operation. Although it is important that research centers continue to study the natural history of carotid artherosclerosis and serial changes after carotid endarterectomy, these results suggest that for routine clinical follow-up, frequent and expensive periodic tests to detect recurrent stenosis may not be warranted.

Aged↗
PubMed1984

Trends in reconstruction for atherosclerotic renal vascular disease.

Twenty-eight patients underwent renal vascular reconstruction for atherosclerotic renal vascular stenosis. Ten patients had therapeutic renal artery reconstruction for isolated renal artery stenosis causing severe hypertension, nine patients had therapeutic renal artery reconstruction for severe hypertension combined with simultaneous aortic reconstruction, and nine patients had prophylactic renal artery reconstruction for renal artery stenosis combined with simultaneous aortic reconstruction. Ninety percent of patients undergoing therapeutic renal revascularization procedures for hypertension were cured or improved. The 10 patients undergoing prophylactic renal artery reconstruction combined with aortic reconstruction had an average 72 percent reduction in the diameter of the vessel. Dacron side grafts sutured to the aortic graft were used for revascularization in each of the patients with prophylactic revascularization and was found to be an expedient means of reconstruction with good patency rates. No increased morbidity or mortality rate was noted in the prophylactic group. We believe that prophylactic revascularization should be carried out in patients with atherosclerotic high-grade stenosis of the renal arteries to prevent hypertension and preserve renal function.

Aged↗
PubMed1984

Subtotal parathyroidectomy for secondary hyperparathyroidism.

Controversy exists regarding the relative merits of subtotal parathyroidectomy (SPTX) versus total parathyroidectomy with autotransplantation in the treatment of secondary hyperparathyroidism (HPT). Fourteen patients who underwent SPTX for secondary HPT were evaluated to determine the efficacy of this treatment in view of modern dialysis, diet, and drug treatment. Indications for operation included intractable symptoms (two patients), progressive renal osteodystrophy (eight patients), or both (four patients). Duration of renal failure ranged from 3 to 15 years (mean 7.8 years) before SPTX. The operative serum calcium level was normal in 10 patients, elevated in three patients, and low in one patient. Preoperative parathyroid hormone (PTH) levels ranged from 3.9 to 144 ng/ml (average 41 ng/ml) and decreased after operation to an average of 3.6 ng/ml (normal PTH less than 1 ng/ml). There were no deaths or major postoperative complications. Clinical or radiographic improvement occurred in 80% of patients but did not correlate with absolute reductions in PTH levels. Our results reveal that SPTX is a simple and effective treatment in the initial surgical management of uremic, secondary HPT and appears to be comparable to those obtained with more complicated surgical approaches such as total parathyroidectomy and autotransplantation.

Adult↗
PubMed1983

Alloplastic implants of the larynx.

Biocompatible Teflon fluorocarbon polymer (Proplast) and porous polyethylene (Plasti-Pore) are porous alloplastic implant materials that are widely used in reconstructive head and neck surgery. These two materials were used in our study as replacement grafts for defects in three groups of 12 canines. For the first time, Plasti-Pore was found equal and perhaps superior to Proplast in deep implantation, this in the anterior cricoid cartilage when the internal and external perichondrium were preserved. Rejection of both substances occurred when the implant was exposed to air and aerodigestive tract contaminants after the removal of the perichondrium, subglottic, and upper tracheal mucosa. Airway exposure to the alloplasts, even when lined with buccal mucosa, resulted in infection and extrusion, but at a much slower rate.

Animals↗
PubMed1983

Renal microembolization syndrome. A cause for renal dysfunction after abdominal aortic reconstruction.

Moderate renal dysfunction due to renal microembolization developed in eight patients who underwent abdominal aortic reconstruction for aneurysmal or occlusive disease. In each patient, the aorta around the renal arteries was thrombus-lined or severely ulcerated and was therefore the source of embolization, and aortic clamping near the renal arteries was required and provided the mechanism for embolization. Renal failure was moderate and did not require dialysis. Renal dysfunction appeared to be largely reversible, although some degree of permanent damage did occur. Similar changes in renal function were noted in a dog model of renal microembolization. Prevention of this complication depends on awareness of aortic lesions that increase the risk of renal embolization.

Acute Kidney Injury↗
PubMed1983

Aortoiliac reconstruction combined with nonvascular operations.

Seventy-six patients with aortoiliac reconstruction and associated intraabdominal procedures were compared with 445 patients with aortoiliac revascularization alone to provide information about the associated morbidity and mortality of adding a nonvascular procedure to aortic reconstruction. Patients with aortoiliac reconstruction for limb salvage had a significant increase in complications when an abdominal procedure was performed in association with aortoiliac reconstruction (66 percent versus 14 percent, p less than 0.01). Additionally, patients with elective aortoiliac reconstruction had a significant increase in mortality when an abdominal procedure was performed in addition to aortoiliac reconstruction (9 percent versus 3 percent, p less than 0.01). A small bowel obstruction and a pancreatic pseudocyst occurred as a direct result of the associated abdominal procedure. None of the deaths could be directly attributed to a concomitant abdominal procedure. The demonstration of an increase in morbidity and mortality with the addition of nonvascular procedures to aortoiliac reconstruction, even though certain subgroups of patients underwent aortic revascularization, suggest that the surgeon must carefully weigh the benefits and risks before combining vascular and nonvascular operations.

Adult↗
PubMed1983

Isolation of the beta-tubulin gene from yeast and demonstration of its essential function in vivo.

A DNA fragment from yeast (Saccharomyces cerevisiae) was identified by its homology to a chicken beta-tubulin cDNA and cloned. The fragment was shown to be unique in the yeast genome and to contain the gene for yeast beta-tubulin, since it can complement a benomyl-resistant conditional-lethal mutation. A smaller subfragment, when used to direct integration of a plasmid to the benomyl resistance locus in a diploid cell, disrupted one of the beta-tubulin genes and concomitantly created a recessive lethal mutation, indicating that the single beta-tubulin gene of yeast has an essential function. Determination of the nucleotide sequence reveals extensive amino acid sequence homology (more than 70%) between yeast and chicken brain beta-tubulins.

Amino Acid Sequence↗
PubMed1983

Transmesocolic omentoplasty.

Transmesocolic omentoplasty is a simple technique for covering prosthetic aortic grafts and preventing aortoenteric fistulas. It is especially valuable in repeat aortic procedures when mobilization of periaortic tissues and graft coverage may be impossible.

Aorta↗