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Biomedical subjects

W K Nichols

Publications and source records attributed to W K Nichols.

At least 37 records · Page 2Linked to original sources
PubMed1991

Complete external iliac artery disruption after percutaneous aortic valvuloplasty in two young children: successful repair with hypogastric artery transposition.

The majority of vascular injuries in young children are iatrogenic. This is a report of two complete external iliac artery disruptions occurring during percutaneous transfemoral balloon aortic valvuloplasty in a 2-year-old and a 5-year-old child. The damaged external iliac artery was bypassed by extensively mobilizing the hypogastric surgery and rotating it upward to anastomose it to the proximal common femoral artery. Normal limb pulses, function, and growth were noted in follow-up.

Anastomosis, Surgical↗
PubMed1990

Bioactivation of 3-methylindole by isolated rabbit lung cells.

3-Methylindole (3MI) is a pneumotoxin that causes selective lung lesions indicative of Clara cell and alveolar epithelial cell damage in ruminants and rodents. The present study examined the cytotoxicity of 3MI to isolated rabbit Clara cells, type II alveolar epithelial cells, and alveolar macrophages. 3MI produced a dose-dependent cytotoxicity to Clara cells detectable within 1 hr of incubation at 37 degrees C which reached a maximum at 3 hr. Concentrations of 0.25 and 0.5 mM 3MI were cytotoxic to Clara cells, while type II and alveolar macrophages required 1 mM 3MI before cytotoxicity was observed. The cytochrome P450 suicide substrate inhibitor, 1-aminobenzotriazole, inhibited 3MI-induced cytotoxicity in Clara cells, type II cells, and alveolar macrophages. These observations were consistent with a cytochrome P450-mediated bioactivation of 3MI to a toxic intermediate. Studies with a trideuteromethyl analog of 3MI demonstrated a much reduced cytotoxicity to Clara cells as well as to type II cells, and macrophages. The deuterium isotope effect suggested that C-H bond breakage at the 3-methyl group is a requisite oxidative transformation in the bioactivation of 3MI to a selective lung cell cytotoxin. The selectivity of cellular cytotoxicity is probably associated with higher rates of bioactivation by Clara cell cytochrome P450 monooxygenases compared to those of type II cells and macrophages. These studies demonstrate that 3MI is bioactivated in isolated pulmonary cells without the intervention of other organs and that bioactivation requires functional cytochrome P450 enzymes.

Animals↗
PubMed1990

Total parathyroidectomy and autotransplantation in hyperplasia of the parathyroid gland.

Hyperparathyroidism caused by multiple-gland hyperplasia has traditionally been treated by subtotal parathyroidectomy. Excellent results have been reported by some, particularly in primary hyperparathyroidism, but other have reported a significant incidence of recurrent hyperparathyroidism. Since 1979, we have chosen to avoid the possibility of remedial exploration of the neck and its attendant risks by treating all patients with primary and secondary hyperplasia with total parathyroidectomy and heterotopic autotransplantation. A total of 20 patients were studied. There were no failures of grafts and no operative complications. We conclude that this procedure is a reliable and safe alternative in the treatment of primary or secondary hyperplasia of the parathyroid gland.

Adult↗
PubMed1989

Diagnostic dilemma of an unsuspected hyperfunctioning accessory parathyroid gland after total parathyroidectomy with autotransplantation in a peritoneal dialysis patient.

Persistent or recurrent hyperparathyroidism in patients with chronic renal failure may be a frustrating problem. We report a case history of a peritoneal dialysis patient who underwent total parathyroidectomy with autotransplantation for secondary hyperparathyroidism, developed tertiary hyperparathyroidism, and in an attempt to control hypercalcemia underwent seven partial resections of the autotransplant. Subsequently, a total excision of the parathyroid autograft was performed, but the patient continued to have hyperparathyroidism and unexpectedly was found to have a hyperplastic fifth parathyroid gland identified by thallium-technetium subtraction scan. The fifth gland was removed, and a part was implanted in the right forearm; however, the autoimplant had to be completely removed because of rapidly developing hypercalcemia. Hypercalcemia was controlled, but elevated levels of parathormone persisted. Remaining parathyroid tissue could not be found.

Female↗
PubMed1989

Transaxillary or supraclavicular decompression for the thoracic outlet syndrome. A comparison of the risks and benefits.

The difficult exposure with the transaxillary resection of the first rib (TAR) prompted an analysis of the TAR versus the supraclavicular approach (SCR) for decompressing the thoracic outlet in patients with thoracic outlet syndrome (TOS). Thirty-seven patients underwent 30 TAR and 15 underwent SCR for TOS. The operating time was similar for the two groups. Mean blood loss was 61 cc for the SCR group and 218 cc for the TAR group. There was one complication in the SCR group, a urinary tract infection, whereas the TAR group had 21 complications including pneumothorax (13), laceration of subclavian vessel (3), winged scapula (3), pleural effusion (1), and wound infection (1). Postoperative hospitalization averaged 3 and 5 days, respectively, for the SCR and TAR patients. All SCR patients and all but one TAR patient were improved or asymptomatic immediately postoperatively. Ninety-three per cent and 81 per cent, respectively, of SCR and TAR patients were improved at 2 months, whereas 100 per cent and 83 per cent, respectively, remained improved at a mean follow-up of 3 years. The significantly fewer complications, decreased blood loss and shorter postoperative hospitalization, noted in the SCR patients supports this approach as the preferred form of management for TOS.

Adult↗
PubMed1989

Late occurrence of aortoenteric fistula. After removal of a prosthetic graft.

Aortoenteric fistula is an uncommon but devastating complication of aortic surgery. The authors present a case of aortoenteric fistula occurring several years after resection of an aortic prosthesis that had not previously been involved in fistula formation. The pathophysiology and clinical evaluation of aortoenteric graft fistula are discussed.

Aorta, Thoracic↗
PubMed1989

Thrombocytopenia associated with heparin-coated catheters in patients with heparin-associated antiplatelet antibodies.

Thrombocytopenia was associated with the presence of heparin-coated pulmonary artery catheters in 12 patients with heparin-associated antiplatelet antibodies. The thrombocytopenia persisted so long as the heparin-coated catheters were in place, even when all other sources of heparin were discontinued. The high morbidity and mortality associated with heparin-induced thrombocytopenia mandates that heparin administration cease and that all heparin-coated catheters be removed from patients with heparin-associated antiplatelet antibodies.

Aged↗
PubMed1988

Surgical management of refractory venous stasis ulceration.

A 15-year experience with 27 patients, 20 to 75 years of age, with refractory venous stasis ulcers is presented. All patients had been managed with support hose, elevation, elastic wraps, Unna's paste boots, and graduated compression stockings. Because of multiple recurrences of their ulcers, the patients were offered surgical treatment to reduce the venous hypertension in the areas of ulceration. The 27 patients had 32 modified Linton procedures. Five had bilateral procedures. At the time of operation, 18 limbs had medial malleolar ulcers, five had bimalleolar ulcers, four had lateral ulcers, three had posterior ulcers, and two patients were free of ulcer. Medial incisions were used in 20 limbs, lateral incisions in six, medial and lateral incisions in three, and midposterior incisions in three. Split-thickness skin grafts were placed on six limbs the day of surgery and on 22 limbs 4 to 7 days later. Postoperative complications included deep venous thrombosis in two, partial flap necrosis in three, and cellulitis of the lower leg in three patients. Follow-up has ranged from 6 months to 10 years. During the most recent clinic visits, 21 limbs were completely healed, whereas six limbs had a recurrence of the ulcer. Five patients have been lost to follow-up. The good long-term results in 78% of the cases indicate that patients with recurrent venous stasis ulcers may receive lasting benefit from modified Linton procedures.

Adult↗
PubMed1988

Aneurysms and pseudoaneurysms of the superficial temporal artery caused by trauma.

Superficial temporal artery (STA) aneurysms as a result of trauma represent less than 1% of reported aneurysms. During the past 200 years only the type of trauma and the preferred treatment have significantly changed. Patients are generally young men with a recent history of blunt head trauma. They may complain of a mass, headache, or other vague symptoms. Neurologic defects are rare; however, if a neurologic deficit exists, the physician should consider either arteriography or a head CT scan to search for intracranial pathologic conditions. In most cases the diagnosis may be made by obtaining a complete history and physical examination. The treatment of choice is ligation and resection, which may be accomplished with the patient under local or general anesthesia. In rare instances, arteriography with selective embolization may be useful when the traumatic aneurysm is complicated by severe facial trauma. Three cases of STA aneurysms are presented. The history, pathophysiology, origin, presentation, diagnosis, differential diagnosis, and treatment of STA aneurysms are reviewed.

Adolescent↗
PubMed1987

Differential effects of cartilage-derived growth factor stimulation of collagen secretion by bovine aortic and microvascular endothelial cells.

Cartilage-derived growth factor (CDGF), a protein closely related to basic fibroblast growth factor, is known to have both mitogenic and chemokinetic properties in microvascular endothelial cells (MVEC). Because of the angiogenic properties of CDGF and its rate in accelerating wound repair, the capacity of this factor to stimulate both proliferation and matrix synthesis was compared in distinct populations of vascular endothelial cells: MVEC from bovine adrenal cortex and macrovascular endothelial cells from the bovine aorta (BAEC). No significant differences in the responses to mitogenic stimulation using CDGF (5-100 units/ml) were observed using MVEC and BAEC. Only rapidly dividing MVEC, however, showed significant increases in collagen secretion in the presence of CDGF. The differential responsiveness of these two cell populations to a defined growth factor underscores the phenotypic diversity of endothelium.

Animals↗
PubMed1986

Effect of heparin on platelet aggregation inhibited by PGI2, trifluoperazine and verapamil.

The enhancement of platelet aggregation by heparin in the presence of certain inhibitors of aggregation was investigated in an attempt to discern the mechanism through which heparin alters platelet function in plasma. These studies were performed by adding prostaglandin I2 (PGI2), verapamil, or trifluoperazine to platelet-rich plasma (PRP) in the presence or absence of heparin. Adenosine diphosphate (ADP), collagen, or arachidonic acid were used for induction of platelet aggregation. The inhibitory agents reduced platelet aggregation to 5 to 20% of control in the absence of heparin. When present in the reaction mixture along with the inhibitor, heparin restored aggregation to approximately 57 to 92% of control depending on the inhibitor and aggregating agent. This proaggregatory action of heparin was observed when heparin and PGI2 were preincubated together or separately for 20 min prior to the addition of PRP and ADP. Results were similar regardless of the sequence in which PGI2 and heparin were added to PRP, and irrespective of the time of incubation of platelets with PGI2. No suppression of platelet cyclic AMP concentration was observed with heparin alone. Heparin also failed to reduce the magnitude of platelet cyclic AMP accumulation promoted by PGI2, forskolin, or a mixture of PGI2 and forskolin. These observations suggest that heparin promoted platelet aggregation and partially overcame the effect of certain inhibitory agents by mechanism(s) that did not involve a reduction of platelet cyclic AMP.

Blood Platelets↗
PubMed1986

Benign intracranial hypertension: a complication of subclavian vein catheterization and arteriovenous fistula.

Thrombosis of the right innominate vein occurred in a patient on maintenance hemodialysis following repeated subclavian vein catheterization. The patient had a functional right brachial arteriovenous fistula for blood access that resulted in a massive retrograde blood flow into the cerebral venous system with the development of the benign intracranial hypertension. The symptoms and signs of intracranial hypertension abated following ligation of the arteriovenous fistula. This unusual association of benign intracranial hypertension with an arteriovenous fistula and innominate vein thrombosis has not been reported previously. Pertinent literature dealing with benign intracranial hypertension and complications of subclavian vein catheterization is reviewed.

Arteriovenous Fistula↗
PubMed1986

Is thrombosis of the infrarenal abdominal aortic aneurysm an acceptable alternative?

Aortic aneurysm thrombosis with extra-anatomic bypass has been proposed for persons with infrarenal aortic aneurysms who are "too debilitated" to undergo standard aortic reconstruction. Thirteen patients (mean age, 75 years) were selected between January 1980 and June 1984 for axillobifemoral bypass with bilateral iliac artery occlusion to manage their infrarenal aortic aneurysms (mean size, 6.3 cm; range, 4.9 to 7.5 cm). Preoperative risk factors were cardiac (angina, compensated congestive heart failure, and significant preoperative arrhythmias), 100% of patients; pulmonary (symptomatic chronic obstructive pulmonary disease with a 1-second forced expiratory volume less than 50% of the predicted value), 46% of patients; renal (creatinine value greater than or equal to 2.0 mg/dl or creatinine clearance less than 20 ml/min), 46% of patients; or nutritional (albumin less than or equal to 3.5 gm/dl or body weight less than 90% of ideal), 46%. Ninety-two percent of the patients had two risk factors whereas 46% had three or more risk factors. The operative mortality rate was 31%; three patients died of multisystem organ failure and another died of thrombin-induced consumptive coagulopathy and hemorrhage. (Our operative mortality rate for conventional graft replacement of abdominal aortic aneurysms is less than 3%.) Morbidity in persons surviving at least 1 month included thrombosis of the extra-anatomic bypass graft requiring thrombectomy (three patients), ischemic colitis (two patients), ischemic neuropathy (one patient), and patients), ischemic colitis (two patients), ischemic neuropathy (one patient), and bilateral above-knee amputations (one patient). Thrombosis of the aneurysm was not achieved in two patients despite use of fluoroscopically controlled embolization of runoff vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

Treatment of spondyloptosis by two stage L5 vertebrectomy and reduction of L4 onto S1.

A new method of treatment of spondyloptosis is presented utilizing a staged approach. The first stage consists of a vertebral body resection of L5 along with the L4-5 and L5-S1 discs. The second stage procedure consists of removal of the loose posterior element, the articular processes, and pedicles of L5 and reduction of L4 onto the sacrum. The technique for the procedure is reviewed along with its results in two operated patients.

Adolescent↗
PubMed1984

Induction of ornithine decarboxylase, RNA, and protein synthesis in macrophage cell lines stimulated by immunoadjuvants.

Early biochemical changes associated with adjuvant stimulation of macrophage protein synthesis were studied using two murine macrophage cell lines, PU5-1.8 and J774.1. An induction of ornithine decarboxylase (ODC) was detected 2 hours after exposure of PU5-1.8 and J774.1 cells to two crude immunoadjuvants, BCG cell walls (BCGcw) and lipopolysaccharides from Escherichia coli (LPS). The chemically defined immunoadjuvant glycopeptide, N-acetyl-muramyl-L-alanyl-D-isoglutamine (MDPL) also promoted an increase in ODC activity at 2 hours that was maximal after 4 hours, while little or no effect was observed with the D-alanyl analog (MDPD) that is devoid of adjuvant activity. The increase in ODC activity promoted by BCGcw in PU5-1.8 and J774.1 cells returned toward control levels by 6 to 8 hours. BCGcw also stimulated RNA and protein synthesis which remained elevated for at least 24 hours and was associated with a decrease in DNA synthesis and cell proliferation. ODC induction by BCGcw and MDPL was enhanced by the addition of PGE2 in both cell lines. Indomethacin slightly depressed the magnitude of ODC stimulation by BCGcw in J774.1 cells but failed to alter the response of PU5-1.8 cells. Additional observations indicated that the induction of ODC by BCGcw in both cell lines was preceded by an activation of cyclic AMP-dependent protein kinase. These observations suggest that a cyclic AMP-mediated induction of ODC may be an early biochemical marker of adjuvant stimulation in macrophages.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1984

LPS stimulation of complement (C3) synthesis by a human monocyte cell line.

The human monocyte-like cell line, U937, was utilized as a model system to assess the influence of lipopolysaccharides (LPS) from Escherichia coli and other immunomodulatory agents on the biosynthesis of complement component C3 by monocytoid cells. The amount of C3 accumulated in the medium of cultured cells was measured by an enzyme-linked immunoabsorbent assay (ELISA). In the presence of LPS (0.01 and 0.10 microgram/ml) C3 production by U937 cells was increased by 2- and 5-fold, respectively. C3 production was also increased in the presence of lymphokine-containing supernatants obtained from human peripheral blood mononuclear cells after their stimulation with concanavalin A-sepharose. Human gamma-interferon (50-500 units/ml) stimulated C3 production by U937 cells. Stimulation of C3 production by LPS or mononuclear cell supernatants was blocked by cycloheximide. LPS (0.10 and 1.0 microgram/ml) also stimulated PGE2 production by U937 cells but failed to increase PGE2 at the lowest concentration (0.01 micrograms/ml) shown to increase C3 biosynthesis. Although exogenous PGE1 (10(-7) and 10(-6) M) promoted a small increase in C3 production, the effect of LPS was not decreased by a concentration of indomethacin (10(-6) M) that inhibited biosynthesis of PGE2. Therefore, LPS-induced C3 synthesis is not mediated by an increase in PGE2 in U937 cells. In summary, these observations suggest that C3 biosynthesis by monocytes/macrophages can be modulated by mediators of cellular immune responses found in the microenvironment of a localized inflammatory reaction.

Alprostadil↗
PubMed1983

Peritoneal access and related complications in continuous ambulatory peritoneal dialysis.

Over a four-year period, 50 patients underwent continuous ambulatory peritoneal dialysis. After 24 months, 48 percent of the patients continued to receive continuous ambulatory peritoneal dialysis treatment (including those who underwent continuous ambulatory peritoneal dialysis with bottled solutions from 1977 to 1978). Using solutions in plastic bags, 63 percent of patients continued to undergo continuous ambulatory peritoneal dialysis after 24 months. The mortality rate at 24 months was 23 percent overall and 15 percent for those using plastic bags. There was an overall average of 2.4 episodes of peritonitis a year per patient and 1.3 episodes a year per patient from 1979 through 1980, when only the technique with plastic bags was used. The number of days a patient was hospitalized averaged 48 per year, and 37 days per year in 1979 and 1980. Fifty-five percent of catheters remained functional at 24 months. Other complications included 15 hernias, 15 skin and tunnel infections, 12 leaks, and five cuff extrusions. Improved catheters and further reductions in the incidence of peritonitis will most likely result in a decreased number of patients who withdraw from continuous ambulatory peritoneal dialysis therapy.

Adolescent↗