Hobart W. Harris

Human very low density lipoproteins and chylomicrons can protect against endotoxin-induced death in mice.

Endotoxemia stimulates many physiologic responses including disturbances in lipid metabolism. We hypothesized that this lipemia may be part of a defensive mechanism by which the body combats the toxic effects of circulating endotoxin. We tested the effects of mixtures of endotoxin, lipoproteins, and lipoprotein-free plasma and determined the ability of varying concentrations of human very low density lipoproteins (VLDL) and chylomicrons, as well as low density lipoproteins (LDL) and high density lipoproteins (HDL), and of the synthetic lipid emulsion SOYACAL to prevent endotoxin-induced death in mice. This study demonstrates that the triglyceride-rich VLDL and chylomicrons, as well as cholesterol-rich LDL and HDL, and cholesterol-free SOYACAL can protect against endotoxin-induced death. Protection required small amounts of lipoprotein-free plasma, and depended on the incubation time and the concentration of lipoprotein lipid. Despite stringent techniques to prevent exogenous endotoxin contamination eight of ten duplicate VLDL preparations contained endotoxin (5,755 +/- 3,514 ng endotoxin/mg triglyceride, mean +/- SEM) making the isolation of endotoxin-free VLDL difficult. In contrast, simultaneous preparations of LDL and HDL were relatively free of endotoxin contamination (3 +/- 3 and 320 +/- 319 ng/mg total cholesterol, respectively), suggesting that the contamination of VLDL occurs in vivo and not during the isolation procedure. These observations suggest a possible role for increased triglyceride-rich lipoproteins in the hosts defense against endotoxemia and infection.

Randomized, Double-Blind, Placebo-Controlled Trial of Cephalexin for Treatment of Uncomplicated Skin Abscesses in a Population at Risk for Community-Acquired Methicillin-Resistant Staphylococcus aureus Infection

ABSTRACT Empirical use of beta-lactam antibiotics, the preferred agents for treating uncomplicated skin and soft tissue infections, may no longer be appropriate for these infections because of the increasing prevalence of community strains of methicillin-resistant Staphylococcus aureus (MRSA). Retrospective studies, however, suggest that outcomes are good even when beta-lactams are used. We conducted a randomized, double-blind trial of 166 outpatient subjects comparing placebo to cephalexin at 500 mg orally four times for 7 days after incision and drainage of skin and soft tissue abscesses. The primary outcome was clinical cure or failure 7 days after incision and drainage. S. aureus was isolated from 70.4% of abscess cultures. Of the isolates tested 87.8% were MRSA, 93% of which were positive for Panton-Valentine leucocidin genes. Clinical cure rates were 90.5% (95% confidence interval, 0.82 to 0.96) in the 84 placebo recipients and 84.1% (95% confidence interval, 0.74 to 0.91) in the 82 cephalexin recipients (difference in the two proportions, 0.0006; 95% confidence interval, −0.0461 to 0.0472; P = 0.25). The 90.5% cure rate observed in the placebo arm and 84.1% cure rate observed in the cephalexin arm provide strong evidence that antibiotics may be unnecessary after surgical drainage of uncomplicated skin and soft tissue abscesses caused by community strains of MRSA.

Chylomicrons alter the fate of endotoxin, decreasing tumor necrosis factor release and preventing death.

The hypertriglyceridemia of infection was traditionally thought to represent the mobilization of substrate to fuel the bodys response to the infectious challenge. However, we have previously shown that triglyceride-rich lipoproteins can protect against endotoxin-induced lethality. The current studies examine the mechanism by which this protection occurs. Rats infused with a lethal dose of endotoxin preincubated with chylomicrons had a reduced mortality compared with rats infused with endotoxin alone (15 vs. 76%, P < 0.001). Preincubation with chylomicrons increased the rate of clearance of endotoxin from plasma and doubled the amount of endotoxin cleared by the liver (30 +/- 1 vs. 14 +/- 2% of the total infused radiolabel, P < 0.001). In addition, autoradiographic studies showed that chylomicrons directed more of the endotoxin to hepatocytes and away from hepatic macrophages. Rats infused with endotoxin plus chylomicrons also showed reduced peak serum levels of tumor necrosis factor as compared with controls (14.2 +/- 3.3 vs. 44.9 +/- 9.5 ng/ml, mean +/- SEM, P = 0.014). In separate experiments, chylomicrons (1,000 mg triglyceride/kg) or saline were infused 10 min before the infusion of endotoxin. Chylomicron pretreatment resulted in a reduced mortality compared with rats infused with endotoxin alone (22 vs. 78%, P < 0.005). Therefore, chylomicrons can protect against endotoxin-induced lethality with and without preincubation with endotoxin. The mechanism by which chylomicrons protect against endotoxin appears to involve the shunting of endotoxin to hepatocytes and away from macrophages, thereby decreasing macrophage activation and the secretion of cytokines.

Prospective Randomized Trial of LC+LCBDE vs ERCP/S+LC for Common Bile Duct Stone Disease

OBJECTIVE To compare outcome parameters for good-risk patients with classic signs, symptoms, and laboratory and abdominal imaging features of cholecystolithiasis and choledocholithiasis randomized to either laparoscopic cholecystectomy plus laparoscopic common bile duct exploration (LC+LCBDE) or endoscopic retrograde cholangiopancreatography sphincterotomy plus laparoscopic cholecystectomy (ERCP/S+LC). DESIGN Our study was a prospective trial conducted following written informed consent, with randomization by the serially numbered, opaque envelope technique. SETTING Our institution is an academic teaching hospital and the central receiving and trauma center for the City and County of San Francisco, California. PATIENTS We randomized 122 patients (American Society of Anesthesiologists grade 1 or 2) meeting entry criteria. Ten of these patients, excluded from outcome analysis, were protocol violators having signed out of the hospital against medical advice before 1 or both procedures were completed. INTERVENTIONS Treatment was preoperative ERCP/S followed by LC, or LC+LCBDE. MAIN OUTCOME MEASURES The primary outcome measure was efficacy of stone clearance from the common bile duct. Secondary end points were length of hospital stay, cost of index hospitalization, professional fees, hospital charges, morbidity and mortality, and patient acceptance and quality of life scores. RESULTS The baseline characteristics of the 2 randomized groups were similar. Efficacy of stone clearance was likewise equivalent for both groups. The time from first procedure to discharge was significantly shorter for LC+LCBDE (mean [SD], 55 [45] hours vs 98 [83] hours; P < .001). Hospital service and total charges for index hospitalization were likewise lower for LC+LCBDE, but the differences were not statistically significant. The professional fee charges for LC+LCBDE were significantly lower than those for ERCP/S+LC (median [SD],

Memory regulatory T cells reside in human skin.

4820 [1637] vs

Enteric Fistulas: Principles of Management

6139 [1583]; P < .001). Patient acceptance and quality of life scores were equivalent for both groups. CONCLUSIONS Both ERCP/S+LC and LC+LCBDE were highly effective in detecting and removing common bile duct stones and were equivalent in overall cost and patient acceptance. However, the overall duration of hospitalization was shorter and physician fees lower for LC+LCBDE. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00807729.

Changing management of gallstone disease during pregnancy

Regulatory T cells (Tregs), which are characterized by expression of the transcription factor Foxp3, are a dynamic and heterogeneous population of cells that control immune responses and prevent autoimmunity. We recently identified a subset of Tregs in murine skin with properties typical of memory cells and defined this population as memory Tregs (mTregs). Due to the importance of these cells in regulating tissue inflammation in mice, we analyzed this cell population in humans and found that almost all Tregs in normal skin had an activated memory phenotype. Compared with mTregs in peripheral blood, cutaneous mTregs had unique cell surface marker expression and cytokine production. In normal human skin, mTregs preferentially localized to hair follicles and were more abundant in skin with high hair density. Sequence comparison of TCRs from conventional memory T helper cells and mTregs isolated from skin revealed little homology between the two cell populations, suggesting that they recognize different antigens. Under steady-state conditions, mTregs were nonmigratory and relatively unresponsive; however, in inflamed skin from psoriasis patients, mTregs expanded, were highly proliferative, and produced low levels of IL-17. Taken together, these results identify a subset of Tregs that stably resides in human skin and suggest that these cells are qualitatively defective in inflammatory skin disease.

Predicting Strangulated Small Bowel Obstruction: An Old Problem Revisited

In the past decade, surgeons have seen a quiet but dramatic shift in clinical patterns of enteric fistulas. Despite advances in nutritional care, infection control, and surgical technique, an enterocutaneous fistula (ECF) remains a source of considerable morbidity and mortality. In addition, wide adoption of damage control and the open abdomen in trauma and emergency surgery have confronted surgeons with a new and especially vicious adversary: the enteroatmospheric (or exposed) fistula (EAF). These fistulas, occurring in the midst of an open abdominal wound, are very difficult to control and present a particularly lethal challenge. Such EAFs might well be the most common type of enteric fistula facing surgeons today. Yet this shift in clinical patterns from the classic ECF to the new EAF is still totally disregarded in major surgical texts. The aim of this review is to present current principles in the management of enteric fistulas. Additionally, we will demonstrate how traditional principles of managing enteric fistulas help us to better understand the physiology and natural history of EAFs and to deal effectively with this new challenge.

A prospective, randomized controlled trial of single-incision laparoscopic vs conventional 3-port laparoscopic appendectomy for treatment of acute appendicitis.

AbstractBackground: Symptomatic gallstones may be problematic during pregnancy. The advisability of laparoscopic cholecystectomy (LC) is uncertain. The objective of this study is to define the natural history of gallstone disease during pregnancy and evaluate the safety of LC during pregnancy. Methods: Review of medical records of all pregnant patients with gallstone disease at the University of California, San Francisco, from 1980 to 1996. Results: Of approximately 29,750 deliveries, 47 (0.16%) patients were treated for gallstone disease, including biliary colic in 33, acute cholecystitis in 12, and pancreatitis in two. Conservative treatment was attempted in all patients but failed in 17 (36%) cases. Two patients required combined preterm Cesarean-section cholecystectomy and 10 required surgery in the early postpartum period for persistent symptoms. Seventeen patients required cholecystectomy during pregnancy for biliary colic (10), acute cholecystitis (six), and pancreatitis (one). Three patients were treated with open cholecystectomy. Fourteen patients underwent LC at a mean gestational age of 18.6 weeks, mean OR time of 74 min, and mean length of stay of 1.2 days. Hasson cannulation was utilized in 11 patients. Reduced-pressure pneumoperitoneum (6–10 mmHg) was used in seven patients. Prophylactic tocolytics were used in seven patients, with transient postoperative preterm labor observed in one. There were no open conversions, preterm deliveries, fetal loss, teratogenicity, or maternal morbidity. Conclusions: In past years, symptomatic gallstones during pregnancy were managed conservatively or with open cholecystectomy. LC is a feasible and safe method for treating severely symptomatic patients.

Chylomicrons can inhibit endotoxin activity in vitro

BackgroundDiagnosing intestinal strangulation complicating a small bowel obstruction (SBO) remains a considerable challenge. Despite decades of experience and numerous studies, no clinical indicators have been identified that reliably predict this life-threatening condition. Our goal was to determine which clinical indicators in patients with SBO can be used to independently predict the presence of strangulated intestine.MethodsMedical records were reviewed for 192 adult patients operated on for acute SBO over an 11-year period (1996–2006). Seventy-two preoperative clinical, laboratory, and radiologic findings at admission were examined. Data from patients with strangulated intestine were compared to data from patients without bowel compromise. Likelihood ratios were generated for each significant parameter in a multivariate logistic regression analysis.ResultsForty-four patients had bowel strangulation requiring bowel resection, and 148 had no strangulation. The most significant independent predictor of bowel strangulation was the computed tomography (CT) finding of reduced wall enhancement, with a sensitivity and specificity of 56% and 94% [likelihood ratio (LR) 9.3]. Elevated white blood cell (WBC) count and guarding were moderately predictive (LR 1.7 and 2.8).ConclusionRegression analysis of multiple preoperative criteria demonstrates that reduced wall enhancement on CT, peritoneal signs, and elevated WBC are the only variables independently predictive of bowel strangulation in patients with SBO.