Citations

Background— Atherosclerotic renovascular disease may augment deterioration of renal function and ischemic nephropathy compared with other causes of renal artery stenosis (RAS), but the underlying mechanisms remain unclear. This study was designed to test the hypothesis that concurrent early atherosclerosis and hypoperfusion might have greater early deleterious effects on the function and structure of the stenotic kidney. Methods and Results— Regional renal hemodynamics and function at baseline and during vasoactive challenge (acetylcholine or sodium nitroprusside) were quantified in vivo in pigs by electron-beam computed tomography after a 12-week normal (n=7) or hypercholesterolemic (HC, n=7) diet, RAS (n=6), or concurrent HC and a similar degree of RAS (HC+RAS, n=7). Flash-frozen renal tissue was studied ex vivo. Basal cortical perfusion and single-kidney glomerular filtration rate (GFR) were decreased similarly in the stenotic RAS and HC+RAS kidneys, but tubular fluid reabsorption was markedly impaired only in HC+RAS. Perfusion responses to challenge were similarly blunted in the experimental groups. Stimulated GFR increased in normal, HC, and RAS (38.3±3.6%, 36.4±7.6%, and 60.4±9.3%, respectively, P <0.05), but not in HC+RAS (6.5±15.1%). These functional abnormalities in HC+RAS were accompanied by augmented perivascular, tubulointerstitial, and glomerular fibrosclerosis, inflammation, systemic and tissue oxidative stress, and tubular expression of nuclear factor-κB and inducible nitric oxide synthase. Conclusions— Early chronic HC+RAS imposes distinct detrimental effects on renal function and structure in vivo and in vitro, evident primarily in the tubular and glomerular compartments. Increased oxidative stress may be involved in the proinflammatory and progrowth changes observed in the stenotic HC+RAS kidney, which might potentially facilitate the clinically observed progression to end-stage renal disease.

We used single-channel kinetic analysis to study the inhibitory effects of tacrine on human adult nicotinic receptors (nAChRs) transiently expressed in HEK 293 cells. Single channel recording from cell-attached patches revealed concentration- and voltage-dependent decreases in mean channel open probability produced by tacrine (IC50 4.6 μM at −70 mV, 1.6 μM at −150 mV). Two main effects of tacrine were apparent in the open- and closed-time distributions. First, the mean channel open time decreased with increasing tacrine concentration in a voltage-dependent manner, strongly suggesting that tacrine acts as an open-channel blocker. Second, tacrine produced a new class of closings whose duration increased with increasing tacrine concentration. Concentration dependence of closed-times is not predicted by sequential models of channel block, suggesting that tacrine blocks the nAChR by an unusual mechanism. To probe tacrine's mechanism of action we fitted a series of kinetic models to our data using maximum likelihood techniques. Models incorporating two tacrine binding sites in the open receptor channel gave dramatically improved fits to our data compared with the classic sequential model, which contains one site. Improved fits relative to the sequential model were also obtained with schemes incorporating a binding site in the closed channel, but only if it is assumed that the channel cannot gate with tacrine bound. Overall, the best description of our data was obtained with a model that combined two binding sites in the open channel with a single site in the closed state of the receptor.

Abstract.Although pancreatectomy is still performed in a few patients with pancreatic cancer, and nearly all patients who develop pancreatic cancer eventually die of their disease, significant improvements have been made recently. Pancreatectomy is now safer, with major morbidity (hemorrhage, pancreatic anastomotic leak, intraabdominal sepsis) occurring in only about 20% and operative mortality of less than 5%. Two (seemingly subtle) issues cannot be overemphasized when someone carefully studies the literature: (1) There is a crucial difference between actuarial and actual survival, with the former generally being higher whereas the latter is true; and (2) careful re‐review of pathologic specimens (especially in long‐term survivors) initially diagnosed as pancreatic cancer, preferably by an independent pathologist before publishing long‐term results is essential. (Erroneous inclusion of patients with nonductal carcinoma substantially and artificially increases survival.) After curative resection, 5‐year actual survival is realistically about 10% with median survivals of 12 to 18 months. In certain subgroups with favorable pathologic characteristics (neoplasms < 2 cm without nodal or perineural invasion) the prognosis appears to be significantly better, with the 5‐year survival about 20%. The recent improvements in postoperative morbidity and mortality and long‐term outcome (resulting also in decreased cost of care of such patients) have occurred typically in centers with an invested interest in and proven record with pancreatic surgery. Further improvements in survival should be sought at the areas of earlier diagnosis and novel treatments designed to prevent locoregional recurrences; the role of extended resections must be determined by prospective, randomized trials.

AbstractSecondary duct stones are usually detected and easily removed at the time of cholecystectomy either during surgery or endoscopically before or after the operation. Primary duct stone diseases, although much less common, are often a greater therapeutic challenge. These stones may be huge, distributed throughout the biliary tree (including areas difficult to access), and unresponsive to pharmacologic measures. Recurrence of primary duct stones is the rule rather than the exception, and reliable methods for prevention remain to be established. Moreover, morbidity and mortality due to biliary obstruction, sepsis, and choliangiocarcinoma make primary bile duct stone disease a formidable adversary. A better understanding of their pathogenesis can facilitate more effective approaches to treatment and, most important, prevention.

AbstractThe association between thyroid cancer and familial adenomatous polyposis (FAP), albeit rare, is well known. It has been suggested that the thyroid tumors have unique histologic characteristics and may be follicular in origin. Because of their rarity, treatment and long‐term prognosis are uncertain. Twelve such patients (prevalence 399/100,000) seen during 1949–1995 were retrospectively reviewed. Histology was independently re‐reviewed by two pathologists. There were 11 female patients (two sisters) and 1 male patient, with a mean age of 28 years (range 15–61 years). Eight patients (66%) had multicentric tumors and five (42%) bilateral disease. Average tumor diameter was 1.8 cm (range 0.2–5.0 cm). Regional nodal metastases were present in two patients. All 12 thyroid cancers in this series were papillary. The one male patient demonstrated “typical” histology with variable papillary and follicular architecture, whereas the 11 female patients had tumors with unusual histology as described by Harach. Five patients (41%) were treated by total thyroidectomy, five with near‐total thyroidectomy, and two with lobectomy alone. Mean follow‐up was 142 months (range 7 months to 30 years). Regional recurrent disease occurred in two patients, one of whom died of the disease. The 5‐ and 20‐year survivals were 90% and 77%, respectively. The results indicated that all tumors in this study were papillary, although atypical histology was encountered in 91%. The mean age (28 years) is younger than that of patients with sporadic disease. Multicentricity and bilateral disease are common. In view of this finding, total thyroidectomy should be strongly considered. Long‐term prognosis is excellent. The finding of unusual histology in a young patient with papillary thyroid carcinoma should arouse the suspicion of FAP.

AbstractThis prospective randomized study examined the acute‐phase response and wound healing, comparing laparoscopic (LA) and open posterior (PA) adrenalectomy in a cushingoid porcine model. Repository corticotropin gel was given to 40 pigs for 21 days. Biochemical and tissue parameters of Cushing syndrome were confirmed. The pigs were randomized to undergo LA or PA. In addition to operating time and morbidity, the acute‐phase response was compared by measuring the postoperative white blood cell count, fasting glucose, C‐reactive protein, and nitrogen balance. Wound healing was assessed by (1) scored (1–4) gross appearance at 48 hours and 1 and 2 weeks; (2) histologic examination; and (3) tensile strength. There was no difference in operating time (mean ± SD) (36 ± 9 minutes open vs. 37 ± 7 minutes laparoscopic), perioperative mortality, degree of leukocytosis, fasting glucose, or C‐reactive protein (p > 0.05). Nitrogen balance, wound scores, and tensile strength at 24 hours and 1 week were more favorable in the LA group than in the PA group (p < 0.05). In the cushingoid porcine model, laparoscopic adrenalectomy was less catabolic and was associated with fewer wound complications than the open posterior adrenalectomy. These findings provide support for continued pursuit of laparoscopic methods for adrenalectomy in the clinical setting.

AbstractWe currently recommend excision of adrenal incidentalomas ≥ 4 cm in size and all hormonally active tumors. The optimal management and follow‐up of smaller nonfunctioning tumors are controversial. The aim of this study was to determine the clinical outcome of a well defined population of patients with incidentalomas followed without operative intervention. The study group comprised 231 patients, identified from the records of abdominal or thoracic computed tomographic (CT) scans performed between 1985 and 1989. The primary outcome variable analyzed was survival. Follow‐up was obtained by office records, telephone contact, or letter. There were 101 male and 130 female patients with a mean age at diagnosis of 64 years (range 5–86 years). Most adrenal tumors were unilateral (right 113; left 98); 20 were bilateral. Mean tumor size was 2 cm (range 1–6 cm). In nine (4%) patients the tumor was ≥ 4 cm. Follow‐up [mean 7 years; range 1 month (patient died) to 11.7 years] was complete in 224 (97%) patients. Ninety‐one (39%) patients had one or more additional CT scans performed during the follow‐up period, with only four patients demonstrating a > 1 cm increase in the size of the adrenal mass. Surgical excision of these four lesions identified benign pathology. Eighty‐one (35%) patients died of conditions unrelated to adrenal pathology. No patient developed subsequent adrenal hyperfunction or adrenal malignancy. Within the context of our guidelines, conservative management of adrenal incidentalomas considered benign or nonfunctioning at diagnosis is appropriate. Additional information provided by repeat CT scanning appears to confer limited benefit. This study does not support laparoscopic removal of small, nonfunctional adrenal tumors, as has been suggested.

AbstractMany factors have been examined in an attempt to define groups at higher risk for recurrence or recrudescence of Crohn's disease. Among these factors are age and onset of disease, gender, site of disease, number of resections, symptomatic status at the time of surgery, length of small bowel resection, fistulizing versus obstructive forms of disease, proximal margin length, microscopic margin histology, strictureplasty, and number of sites of disease, as well as the presence of colonic only disease, the presence of granulomas, blood transfusions, family history, and prophylactic treatment. To date, only proctocolectomy with Brooke ileostomy versus other procedures for colonic only disease, and prophylactic treatment have been shown with some degree of confidence to lead to a lower recurrence rate after surgery for Crohn's disease.