Correction of metabolic acidosis and its effect on albumin in chronic hemodialysis patients

Serum albumin concentration has been strongly associated with risk of death in hemodialysis patients, with mortality increasing as albumin decreases. Metabolic acidosis stimulates protein catabolism and decreases protein synthesis. A study was undertaken to investigate the effect of increasing predialysis serum bicarbonate (HCO3) concentrations on the nutrition of hemodialysis patients as measured by albumin and total lymphocyte count (TLC). Metabolic acidosis was defined as a predialysis serum bicarbonate concentration of < or = 18 mEq/L. Thirty-six hemodialysis patients were enrolled in the study. Each had been stable on hemodialysis for > or = 3 months and each had a mean serum bicarbonate concentration of < or = 18 mEq/L on predialysis monthly laboratory values during the preceding 3 months. The subjects were randomized into 2 groups. The first group consisted of 18 control subjects who were dialyzed on a standard bicarbonate bath of 35 mEq/L. The second group consisted of 18 experimental patients who were dialyzed on a bicarbonate bath of 40 mEq/L. Subjects in the experimental group who had predialysis serum bicarbonate concentrations less than 22 mEq/L after 2 weeks on the higher bicarbonate bath were additionally supplemented with oral sodium bicarbonate at a dosage of 1 mEq/kg dry weight/d. Monthly predialysis laboratory values were checked for all subjects and included serum electrolytes, blood urea nitrogen, calcium, and albumin. TLCs were obtained at the initiation and at the conclusion of the study. Intact parathyroid hormone, blood pressures, and interdialytic weight gains were also followed. The study lasted 16 weeks; 32 subjects completed the study (16 in each group). There were no statistically significant differences between the two groups at the initiation of the study. The serum bicarbonate concentrations were significantly different between the two groups at the end of the study (control HCO3 17.3 +/- 3.2 mEq/L v experimental HCO3 20.2 +/- 2.9 mEq/L; P = 0.01). Serum albumin concentrations and TLCs were not statistically different (P > 0.05) between the two groups at the end of the study (control albumin 3.88 +/- 0.28 g/dL v experimental albumin 3.76 +/- 0.26 g/dL and control TLC 1,780.0 +/- 779.4/mm3 v experimental TLC 2,020.1 +/- 888.0/mm3). Potassium, intact parathyroid hormone, interdialytic weight gain, blood pressures, Kt/Vs, and protein catabolic rates did not differ. We found that the change in serum bicarbonate concentration was well-tolerated and was without any demonstrable side effects. We conclude that increasing the serum bicarbonate concentration by 3 mEq/L for 16 weeks has no effect on the indicators of nutrition that we measured (serum albumin and TLC).     

Computerized classification of benign and malignant masses on digitized mammograms: a study of robustness

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the robustness of a computerized method developed for the classification of benign and malignant masses with respect to variations in both case mix and film digitization. MATERIALS AND METHODS: The classification method included automated segmentation of mass regions, automated feature-extraction, and automated lesion characterization. The method was evaluated independently with a 110-case database consisting of 50 malignant and 60 benign cases. Mammograms were digitized twice with two different digitizers (Konica and Lumisys). Performance of the method in differentiating benign from malignant masses was evaluated with receiver operating characteristic (ROC) analysis. Effects of variations in both case mix and film digitization on performance of the method also were assessed. RESULTS: Categorization of lesions as malignant or benign with an artificial neural network (or a hybrid) classifier achieved an area under the ROC curve, Az, value of 0.90 (0.94 for the hybrid) on the previous training database in a round-robin evaluation and Az values of 0.82 (0.81) and 0.81 (0.82) on the independent database for the Konica and Lumisys formats, respectively. These differences, however, were not statistically significant (P > .10). CONCLUSION: The computerized method for the classification of lesions on mammograms was robust with respect to variations in case mix and film digitization.     

Endovascular control of patent internal thoracic artery graft in aortic valve surgery

Aortic valve replacement in patients who underwent previous coronary artery bypass with a patent internal thoracic artery is often a challenge because of the risk of graft injury during dissection or difficulties to obtain optimum myocardial protection. Different approaches to myocardial protection or internal thoracic graft dissection and control have been described. Endovascular control of the internal thoracic graft by an angioplasty balloon catheter positioned in the operating room before the operation can be a safe and simple alternative. We report the case of a patient who underwent this technique for aortic valve replacement.     

Technetium-99m hexamethylpropylene amine oxime single-photon emission tomography of regional cerebral blood flow in insulin-dependent diabetes

The study was performed to investigate subclinical abnormalities in regional cerebral blood flow (rCBF) in patients with insulin-dependent diabetes mellitus (IDDM) and to correlate them with patients' characteristics. After intravenous injection of technetium-99m hexamethylpropylene amine oxime (HMPAO), tracer uptake of the prefrontal, frontal and parieto-occipital zones was measured with a triple-head single-photon emission tomography (SPET) camera system in 35 IDDM patients outside an episode of hypoglycaemia. Tracer uptake values in 16 age- and sex-matched healthy volunteers served as reference values. Compared with healthy subjects, increased tracer uptake of both prefrontal regions and the left frontal region could be shown in diabetes. Tracer uptake was negatively correlated with the duration of diabetes in all investigated regions. In diabetic patients with a disease duration of more than 5 years (n=26), stepwise regression analysis revealed a significant positive correlation between their HbA1c levels and tracer uptake. Long-term diabetic patients with reduced (pre)frontal tracer uptake (n=8) had lower HbA1c levels than those without (8.4%±0.2% vs 9.3%±0.3%,P<0.05) and tended to have more frequently a history of hypoglycaemic coma (6/8 vs 6/18,P=0.06). It can be concluded that duration of diabetes contributes to subclinical changes in basal rCBF in IDDM as detected with HMPAO SPET of the brain. The positive correlation between the presence of regional hypoperfusion and lower HbA1c levels in long-term diabetic patients may be interpreted in the light of a presumed higher incidence of hypoglycaemia as metabolic control improves.     

The vasa vasorum and angioplasty

Interruption of flow in the vasa vasorum may lead to medial necrosis and aneurysm formation. The purpose of this study was to determine whether angioplasty produces significant alterations in the morphology or blood flow of the vasa vasorum of the dilated artery. The morphology of the canine vasa vasorum was studied before and after angioplasty; in a separate experiment vessel wall blood flow (VWBF) in canine carotid arteries was measured after angioplasty to determine whether physiologic regulation of the blood flow was disrupted by arterial dilation. No morphologic changes could be demonstrated in the vasa vasorum of the dilated artery; however, VWBF was increased by 1194 +/- 215% (mean +/- standard error, p less than 0.01) between 90 and 120 minutes after angioplasty. VWBF in the adjacent nondilated arterial segment was also increased (720 +/- 177% between 10-30 minutes, p less than 0.01) but returned toward normal after 60 minutes. Adenosine caused a "paradoxical" decrease in VWBF (p less than 0.05) of the dilated arterial segment while causing increased VWBF (p less than 0.05) in the thoracic aorta. Angioplasty appears to produce persistent hyperemia in the dilated arterial wall. A paradoxical response to adenosine suggests that vasa vasorum in the dilated arterial segment are maximally vasodilated. This may be due to mechanical disruption of vasomotor tone or to release of vasoactive substances.     

Oxyntic mucosa pseudopolyps: a presentation of atrophic autoimmune gastritis

Gastric polyps are often present in the setting of atrophic gastritis. Although the majority of these polyps are nonneoplastic, such as hyperplastic polyps, neoplastic polyps may be present. We discuss nine cases that illustrate an additional nonneoplastic cause of polyps in atrophic gastritis. Specifically, preserved islands of relatively normal oxyntic mucosa in a background of gastric atrophy may appear polypoid endoscopically. The patients (seven women, two men, mean age 64 years) presented with nonspecific abdominal or reflux symptoms (n = 8) and diarrhea (n = 1). Five of five patients tested were confirmed to have hypergastrinemia, and three of three patients tested had antiparietal cell antibodies. Biopsies from the gastric body or fundus of our nine patients showed fragments of atrophic mucosa and separate fragments of preserved oxyntic mucosa. Based upon the histologic characteristics of the atrophic fundic and relatively normal antral biopsies, the gastric atrophy appeared to be of autoimmune-type. The relatively preserved oxyntic glands showed parietal cell hypertrophy and focal mild chronic inflammation. The number of polyps observed endoscopically ranged from less than five to multiple/diffuse. Three patients had persistent nodularities in their stomachs for 1, 3, and 7 years of their follow-up. Our study shows that some patients with atrophic gastritis, autoimmune-type, may present with gastric polyps/nodules that represent relatively preserved oxyntic mucosa. This presentation may be more common than is presently recognized because biopsies of the polyps alone will not show histologic features of atrophic gastritis or reveal the etiology of the polyp itself. Although a limited number of previous studies have suggested this type of polypoid presentation may represent "early" atrophic gastritis, its persistence in three of our patients argues against this hypothesis.     

Occult tumor cells in lymph nodes as a predictor for tumor relapse in pancreatic adenocarcinoma

Background and aims Occurrence of tumor relapse is frequent in patients with pancreatic cancer despite the absence of residual tumor detectable at primary surgery and in histopathological examination. Therefore, it has to be assumed that current tumor staging procedures fail to identify minimal amounts of disseminated tumor cells, which might be precursors of subsequent metastatic relapse. The aim of this study was to assess the prognostic impact of minimal tumor cell spread detected in lymph nodes classified as “tumor-free” in routine histopathologic evaluation. Materials and methods A total of 154 “tumor-free” lymph nodes from 59 patients with pancreatic cancer who underwent intentionally curative tumor resection were examined by immunohistochemistry for disseminated tumor cells. Results Fifty (32.5%) of the “tumor-free” lymph nodes obtained from 36 (61%) patients displayed disseminated tumor cells. Multivariate survival analysis revealed that the presence of disseminated tumor cells in “tumor-free” lymph nodes is an independent prognostic factor for both a significantly reduced relapse-free survival (p = 0.03) and overall survival (p = 0.02). Conclusions The frequent occurrence and prognostic impact of immunohistochemically identifiable disseminated tumor cells in lymph nodes of patients with operable pancreatic cancer supports the need for a refined staging system of excised lymph nodes, which should include immunohistochemical examination.     

Diagnostic laparoscopy for chronic abdominal pain after gastric bypass.

BACKGROUND: To evaluate, in an observational study, the utility of diagnostic laparoscopy as a tool to evaluate patients with abdominal pain of unknown etiology after gastric bypass surgery. METHODS: A retrospective analysis was performed of data from patients who had undergone laparoscopy for diagnosis or treatment of abdominal pain. This study included 13 patients with negative preoperative radiographic and/or endoscopic findings. RESULTS: A total of 13 patients who had undergone Roux-en-Y gastric bypass underwent diagnostic laparoscopy for abdominal pain. The findings included internal hernia (4), adhesions (3), ventral hernia (2), partial small bowel obstruction (1), and chronic cholecystitis (1). There were 2 negative laparoscopies, while a diagnosis was made in 85%. After an average follow-up of 3.2 months, 7 of 11 patients had unresolved abdominal pain and 4 patients experienced pain resolution (2 patients were lost to follow-up). CONCLUSION: The results from this small retrospective study suggest that significant pathologic findings can be identified in most patients who have negative preoperative evaluation findings; however, the efficacy of diagnostic laparoscopy to eliminate pain in this patient population requires additional study. Despite the potential complications, we believe that diagnostic laparoscopy has a role in the diagnosis and treatment of chronic abdominal pain after gastric bypass.