Evaluation of academic and community surgery clerkships at a Midwestern medical school.

BACKGROUND: The equivalency of surgical clerkship experience between academic and community sites is an issue that is assessed with difficulty. We examined the objective performance of 222 medical students after completion of the 8-week surgical clerkship. Six different consecutive semesters were analyzed. There were two objective examinations reviewed, the National Board of Medical Examiners' subject examination and the surgical subportion of the Objective Structured Clinical Examination (OSCE) given at the end of the third year. METHODS: Medical students were classified into three separate groups based on the site of their surgical clerkship. The medical students were in either academic (100), community (79), or combined (academic and community) (43) locations. Medical student performance on the subject examination and OSCE was examined after completion of the general surgical clerkship. Single-factor analysis of variance testing was done to compare each of the three groups with respect to subject examination test score, or OSCE score. Significance was defined as P < 0.05. RESULTS: The combined group scored highest on the subject examination (73.6%). The community group scored highest on the OSCE (80.7%). However, no statistical significance exists between the three groups with regard to subject examination (P = NS) or OSCE (P= NS). Subject examination scores did not correlate with OSCE scores (r = 0.095). Objective measurements of surgical subject examination and OSCE were not statistically different between academic, community, and academic and community surgical clerkship participants. CONCLUSIONS: No statistically significant differences exist between the three groups with regards to OSCE failure rates, but the small amount of failures may have caused Type 2 error. Surgical clinical skills as tested by an OSCE and surgical knowledge as tested by a subject examination are equally attained by an academic or community surgical clerkship.

Lipopolysaccharide (LPS) enhancement of outward current in lung pericytes.

Patch clamp methods were used to study the effect of lipopolysaccharide (LPS), an endotoxin produced by gram-negative bacteria, on voltage-dependent outward current of lung pericytes. Pericytes are located in capillary walls and may mediate pathological changes in microvascular hemodynamics and permeability that accompany endotoxin-mediated pulmonary edema. Previous studies have shown that LPS reduces lung pericyte contractility. Lung pericytes exhibited a voltage-dependent outward current, presumed to be K+ current, and this current increased in magnitude in response to LPS. Cells incubated for 48 hr without LPS (control) had an average peak current at 50 mV of 101 pA (n = 5 cells), whereas cells incubated with 100 mg/ml LPS had an average peak current of 927 pA (n = 9 cells, P<0.01 compared to control). When held at 50 mV for 50 msec, net outward current decreased in control cells by 10.7% and in LPS-treated cells by 2.6% (P<0.05). The increased activation of outward current in LPS-treated cells may be due to a previously inactive potassium channel and may mediate LPS-induced relaxation of the lung pericyte.

Differences in arterial and mixed venous IL-6 levels: the lungs as a source of cytokine storm in sepsis.

BACKGROUND: Several investigators have shown that blood levels of interleukin 6 (IL-6) correlate with the severity of illness in critically ill or injured patients. However, little is known about differential arterial and venous blood levels of the cytokine, especially across the lungs. METHODS: We measured differences in IL-6 levels in pulmonary and systemic arterial blood and then documented the production or elimination of IL-6 by the lungs in 19 patients with severe illness. Prospective data were obtained from multiple, simultaneous systemic arterial (ART) and mixed venous (MV) blood samples that were drawn for IL-6 analysis from systemic arterial and pulmonary artery catheters in 7 patients awaiting vascular operation and in 12 trauma patients being treated in the intensive care unit. RESULTS: A lung disorder was present in 5 patients (pneumonia [n = 1], lung trauma [n = 4]) and absent in the remaining 14 patients. The following data were obtained (mean +/- SD) from the highest MV IL-6 levels (pg/mL) in each patient. In patients with a lung disorder (n = 5) compared with those with no disorder (n = 14), ART IL-6 was 9309 +/- 12,521 versus 134 +/- 128 (P =.010), MV IL-6 was 5516 +/- 7420 versus 137 +/- 129 (P =.011), the absolute difference was 3793 +/- 5271 versus -3 +/- 15 (P =.011), and the percentage difference was 37.4% +/- 29.8% versus 1.5% +/- 12.3% (P =.001). The ART and MV IL-6 levels tended to be much higher in the 5 patients with pneumonia (n = 1) and lung injuries (n = 4) than in the patients without apparent pulmonary problems. In addition, the patients with a primary lung disorder demonstrated a net increase in IL-6 levels across the lungs, whereas there was no increase, but rather, a net reduction of IL-6 levels across the lungs in patients without a lung disorder. CONCLUSIONS: The lung appears to be a major producer of IL-6 in patients with an inflammatory lung process. There is a 39% increase in the level of IL-6 as it passes through inflamed lung, producing a marked difference in ART and MV IL-6 levels. Normal lung demonstrated little effect on either ART or MV IL-6 levels.

Reactive oxygen metabolites induce a biphasic contractile response in microvascular lung pericytes.

BACKGROUND: The changes in microvascular permeability characteristic of postinjury inflammation and sepsis may involve dysfunctional regulatory mechanisms at the capillary level. Pericytes, positioned abluminal to microvascular endothelium may, by their contractility, contribute to this regulation. Reactive oxygen metabolites (ROMs), well-known participants in lung inflammation, may exert an effect on pericytes, leading to changes in permeability and adult respiratory distress syndrome. This study investigates the effect of ROMs and antioxidants in an established in vitro assay of pericyte contractility. METHODS: Rat lung pericytes were cultured on collagen gel matrices. After exposure to the ROMs, the surface area of the collagen disks was digitally quantified (an integrated measure of cellular contraction) at 10 and 30 minutes. The cells were exposed to hydrogen peroxide and pyrogallol at 10, 100, and 1,000 micromol/L. Antioxidant effects of catalase (100 micromol/L), superoxide dismutase (100 micromol/L), and pretreatment with vitamin E (1 mmol/L) were quantified. RESULTS: Hydrogen peroxide and pyrogallol induced concentration-dependent relaxation at 10 minutes. Conversely, concentration-dependent contraction was seen at 30 minutes. Catalase completely attenuated both responses, whereas superoxide dismutase had no effect. Vitamin E had no effect at 10 minutes but partially attenuated the contraction seen at 30 minutes. CONCLUSION: ROMs are capable of producing early relaxation and late contraction in cultured lung pericytes. Whereas catalase attenuates both responses, membrane-bound vitamin E only partially attenuates late contraction. This suggests two separate mechanisms: early physiologic relaxation through signaling pathways affecting actin/myosin tone, and late membrane damage causing contraction. Either pathway may cause dysfunction in pulmonary capillary fluid regulation.

Factors affecting mortality rates in patients with abdominal vascular injuries.

BACKGROUND: Major vessel injury is seen in 5% to 25% of patients admitted to hospitals with abdominal trauma, and this is the most common cause of death in these patients. METHODS: Data on 470 patients with abdominal vascular injuries seen at a Level I trauma center were reviewed retrospectively. RESULTS: The overall mortality rate was 45%. The incidence of various types of trauma were blunt in 51 patients (11%), gunshot wounds in 329 patients (70%), shotgun wounds in 21 patients (4%), and stab wounds in 69 patients (15%). The three vessels with the highest mortality rates were aorta (at and proximal to the renals) (32 of 35 [91%]), hepatic veins and/or retrohepatic vena cava (36 of 41 [88%]), and portal vein (25 of 36 [69%]). The most significant risk factors (p < 0.001) for death were a trauma score of 9 or less, initial operating room (OR) systolic blood pressure (SBP) < 90 mm Hg, final OR core temperature < 34 degrees C, 10 or more blood transfusions in the first 24 hours, and an initial emergency department SBP < 70 mm Hg. Of 120 patients with an initial OR SBP < 70 mm Hg, 103 (86%) died. Of 29 patients with a good response to a prelaparotomy thoracotomy with thoracic aortic cross-clamping (SBP > 90 mm Hg within 5 minutes), 11 (38%) survived. Of the remaining 87 patients, only 6 (7%) survived (p = 0.01). CONCLUSION: Rapid control of bleeding sites (to keep blood transfusions to < 10 units) and urgent correction of hypothermia seem to be the main factors improving survival over which the surgeon has some control.

Pericytes augment the capillary barrier in in vitro cocultures.

UNLABELLED: Most in vitro studies of capillary permeability focus on endothelial cell (MVEC) monolayers and ignore the second cell that forms the capillary wall: the microvascular pericyte (PC). We describe a model to study the permeability characteristics of MVEC, PC, and MVEC:PC cocultures. METHODS: Semipermeable culture inserts were coated with collagen and then plated with early passage bovine pulmonary MVEC. On Day 3, bovine pulmonary PC were added at concentrations to approximate MVEC:PC ratios of 1:1, 5:1, and 10:1. Electrical resistance was measured on subsequent days and fluorescently labeled (FITC) albumin was used in a permeability assay to calculate an albumin clearance for each culture. RESULTS: The results for electrical resistance measurements and albumin assays showed a similar pattern. Resistance for endothelial cell monolayers was significantly higher and albumin permeability was significantly lower than that of controls. Addition of pericytes at a 10:1 and 5:1 ratios increased the permeability barrier compared to endothelial cells alone, although these cultures were not significantly different from one another. Cocultures at a 1:1 ratio had the best barrier, significantly better than all other cultures. CONCLUSIONS: Endothelial cell monolayers are an inadequate model of the microcirculation. As PC form a key component of the capillary wall in vivo and as addition of PC to MVEC monolayers in vitro, optimally at a 1:1 ratio, increase their barrier effect to large and small molecules, we believe it is necessary to include both cells in future in vitro studies.

Infectious complications following duodenal and/or pancreatic trauma.

Patients with pancreatic and/or duodenal trauma often have a high incidence of infectious complications. In this study we attempted to find the most important risk factors for these infections. A retrospective review of the records of 167 patients seen over 7 years (1989 through 1996) at an urban Level I trauma center for injury to the duodenum and/or pancreas was performed. Fifty-nine patients (35%) had isolated injury to the duodenum (13 blunt, 46 penetrating), 81 (49%) had isolated pancreatic trauma (18 blunt, 63 penetrating), and 27 (16%) had combined injuries (two blunt, 25 penetrating). The overall mortality rate was 21 per cent and the infectious morbidity rate was 40 per cent. The majority of patients had primary repair and/or drainage as treatment of their injuries. Patients with pancreatic injuries (alone or combined with a duodenal injury) had a much higher infection rate than duodenal injuries. The patients with duodenal injuries had significantly lower penetrating abdominal trauma indices, number of intra-abdominal organ injuries, and incidence of hypothermia. On multivariate analysis independent factors associated with infections included hypothermia and the presence of a pancreatic injury. Although injuries to the pancreas and duodenum often coexist it is the pancreatic injury that contributes most to the infectious morbidity.

Ostomy as a risk factor for posttraumatic infection in penetrating colonic injuries: univariate and multivariate analyses.

BACKGROUND: Primary repair for penetrating colonic injury is an acceptable practice in uncomplicated injuries, but it is still viewed with trepidation in high risk patients. METHODS: The records of 350 patients evaluated at an urban Level I trauma center for penetrating colonic injuries over an 8-year period (1989-1997) were reviewed. These included 33 stab and 317 gunshot wounds. Thirty-nine patients died within 48 hours. Of the remaining 311 patients, 78 (25%) developed 152 infections. These infections were classified as traumatic or nosocomial in nature. Traumatic infections (46%) included abdominal abscesses or peritonitis (28), wound infections (30), missile tract infections (8), and fistulas (4), whereas nosocomial infections (54%) included pneumonia (25), bacteremia (25), urinary tract infections (17), miscellaneous (8), empyema (4), and sinusitis (3). Significance for analyses was set at p < 0.05. RESULTS: Univariate analysis was performed to identify risk factors for the development of infections. The five most significant risk factors, using all infections as an outcome, were as follows: penetrating abdominal trauma index (PATI) greater than 30, presence of an ostomy, multiple transfusions, Injury Severity Score (ISS) of 16 or greater, and Revised Trauma Score less than 7.8. All were highly significant (p < 0.0001). Multivariate analysis with all infections as an outcome revealed that four of the five risk factors had independent effects, with the following significance: PATI greater than 30, ISS of 16 or greater, ostomy, and multiple transfusions. Multivariate analysis for traumatic infections revealed only two of the above to be independent risk factors: presence of an ostomy (p = 0.004) and a PATI greater than 30 (p = 0.039), both of which can be considered local factors. Conversely, multivariate analysis of nosocomial infections revealed independent risk for the two other factors, both of which can be considered systemic factors: multiple transfusions (p = 0.011) and ISS of 16 or greater (p = 0.026). CONCLUSION: Although most of the above factors are beyond the control of the trauma surgeon, the creation of an ostomy is a clinical decision. The creation of an ostomy in high-risk patients does not protect them from septic complications and, indeed, may independently contribute to local abdominal infections.

Factors affecting prognosis with penetrating wounds of the heart.

OBJECTIVE: To determine factors affecting prognosis for patients with penetrating wounds of the heart. METHODS: A retrospective review of 302 patients with penetrating heart wounds undergoing emergency thoracotomy (August of 1980 through June of 1997) in a Level I trauma center. RESULTS: There were 148 patients with gunshot wounds (GSW) and 154 patients with stab wounds with 23% and 58% survival rates, respectively. Of 43 patients having no signs of life at the scene, 5 patients (12%) achieved some cardiac activity and were brought to the operating room (OR), but none survived. Of 67 patients "arresting" in the ambulance, 23 got to the OR, but only 3 patients (4%) survived. Of 27 patients "arresting" in the emergency department (ED), 18 patients reached the OR, but only 5 patients (19%) survived. Of 15 patients having an ED thoracotomy because of rapid deterioration there, 4 patients (27%) survived. Thus, of the 152 patients with an ED thoracotomy, 93 patients had gunshot wounds and none survived; of the 59 with stab wounds, 12 (20%) survived (p < 0.001). Of 150 patients having an OR thoracotomy, 111 (74%) survived. Single-chamber injuries had a survival rate of 51% (112 of 219 patients), but multiple chamber and/or intrapericardial great vessel injuries had only a 13% survival rate (11 of 83 patients) (p < 0.001). Intrapericardial aortic injuries were uniformly fatal in 15 patients. In patients with stab wounds, pericardial tamponade was associated with a higher survival rate (66%; 56 of 84 patients) than in those without tamponade (47%; 33 of 70 patients). CONCLUSION: The physiologic status of the patient at presentation, mechanism of injury, and presence of a tamponade were significant prognostic factors in this series of penetrating cardiac injuries. Multiple-chamber injuries, especially with great vessel involvement, were associated with a high mortality rate. ED thoracotomies for gunshot wounds of the heart were uniformly fatal.

Lipopolysaccharide induces relaxation in lung pericytes by an iNOS-independent mechanism.

Lipopolysaccharide (LPS)-regulated contractility in pericytes may play an important role in mediating pulmonary microvascular fluid hemodynamics during inflammation and sepsis. LPS has been shown to regulate inducible nitric oxide (NO) synthase (iNOS) in various cell types, leading to NO generation, which is associated with vasodilatation. The purpose of this study was to test the hypothesis that LPS can regulate relaxation in lung pericytes and to determine whether this relaxation is mediated through the iNOS pathway. As predicted, LPS stimulated NO synthesis and reduced basal tension by 49% (P < 0.001). However, the NO synthase inhibitors N (omega)-nitro-L-arginine methyl ester, aminoguanidine, and N (omega)-monomethyl-L-arginine did not block the relaxation produced by LPS. In fact, aminoguanidine and N (omega)-monomethyl-L-arginine potentiated the LPS response. The possibility that NO might mediate either contraction or relaxation of the pericyte was further investigated through the use of NO donor compounds; however, neither sodium nitroprusside nor S-nitroso-N-acetylpenicillamine had any significant effect on pericyte contraction. The inhibitory effect of aminoguanidine on LPS-stimulated NO production was confirmed. This ability of LPS to inhibit contractility independent of iNOS was also demonstrated in lung pericytes derived from iNOS-deficient mice. This suggests the presence of an iNOS-independent but as yet undetermined pathway by which lung pericyte contractility is regulated.

Effects of vasoactive mediators on the rat lung pericyte: quantitative analysis of contraction on collagen lattice matrices.

Pericytes are contractile cells of the microvasculature which may contribute to the hypotension and increase in permeability that are present during inflammation and late-stage sepsis. The purpose of this study was to examine the contractile effects, if any, of septic modulators on the lung pericyte. Contractile effects were qualitatively examined using a previously developed silicone rubber method. This study further demonstrates a quantitative method for measuring the contraction of lung pericytes cultured on a collagen lattice. Contraction was measured by the change in collagen matrix area in response to vasoactive stimuli. Bradykinin and serotonin significantly increased contraction in a dose-dependent manner, with a maximum increase in contraction twice that of control. Forskolin and adenosine caused relaxation, also in a significant dose-dependent manner, with a maximum decrease in contraction of 80 and 30-40%, respectively. Histamine had no effect on contractility in either the silicone rubber or the collagen lattice assay. These results show that the lung pericyte, like the retinal pericyte, is a contractile cell and can be stimulated to contract or relax in vitro by the presence of certain inotropic agents present during inflammation and sepsis. These responses may play a role in microvascular regulation.

CD4 cell counts as a prognostic factor of major abdominal surgery in patients infected with the human immunodeficiency virus.

OBJECTIVE: To measure the prognostic utility of helper T-cell (CD4) counts in human immunodeficiency virus (HIV)-infected patients undergoing major abdominal surgery. DESIGN: Retrospective case series. SETTING: Three university-affiliated hospitals. PATIENTS: Forty-three HIV-infected patients undergoing major abdominal surgery. MAIN OUTCOME MEASURES: Morbidity and mortality rates with respect to CD4 cell counts. RESULTS: Nineteen of 32 patients who had CD4 cell counts less than 0.20 X 10(9)/L (200 cells/microL) suffered major complications compared with 2 of 11 patients who had CD4 cell counts greater than 0.20 x 10(9)/L (200 cells/microL) (P=.03). Perioperative mortality was 38% for patients with CD4 cell counts less than 0.20 x 10(9)/L, and was 9% for those with CD4 cell counts greater than 0.20 x 10(9)/L (P=.13). Six months postoperatively, mortality rates were 47% and 9%, respectively (P=.03). Of patients with septic processes perioperatively (n=12), mortality was 75%, and was 19% (P=.009) for those with nonseptic processes (n=31). Nine patients had HIV-related intra-abdominal pathologic conditions at laparotomy. Mortality was 56% perioperatively (P=.13) and 88% after 6 months (P=.001). Sixty-eight percent of patients who received blood product transfusions developed complications, whereas only 7% of those who did not receive transfusions developed complications (P<.001). Overall mortality and morbidity rates were 37% and 49%, respectively. Patients with morbidity had lower CD4 cell counts (median, 0.034 x 10(9)/L) than those without complications (median, 0.102 x 10(9)/L) (P=.02). Similarly, patients who died had lower CD4 cell counts (median, 0.031 x 10(9)/L vs 0.088 x 10(9)/L) (P=.05). CONCLUSIONS: Patients with acquired immunodeficiency syndrome-defining CD4 cell counts undergoing major abdominal surgery developed more complications and had poorer outcomes at 6-month follow-up compared with HIV-infected patients whose CD4 cell counts were greater than 0.20 x 10(9)/L (200 cells/microL). A perioperative septic process and HIV-related pathologic conditions seen at laparotomy are also associated with worse outcomes.

Basic science curriculum during residency: justification based on in-training examination scores.

The American Board of Surgery is increasing its emphasis on competency in surgical basic science as part of residency training. The 1991 American Board of Surgery In-Training Examination (ABSITE) contained 135 questions designated as basic science to assess residents' knowledge. We reviewed the separate progression of scores in clinical and basic sciences at Wayne State University (WSU) surgical residency and nationally through the 1991 ABSITE report. Regression analysis of WSU data yielded a slope (% correct answers per postgraduate year) of 5.3 for clinical and 2.4 for basic science scores (P < 0.001 by t-statistic applied to regression slopes). These data imply a progression of knowledge during residency but at a significantly slower rate for basic science. The national data confirm this trend, although we were unable to evaluate it statistically. This situation illustrates the need for organized teaching of clinically relevant basic science as part of a residency curriculum.

Oxygen transport-dependent splanchnic metabolism in the sepsis syndrome.

OBJECTIVE: Total body oxygen consumption (VO2) may be pathologically oxygen delivery (DO2)-dependent in critically ill patients exhibiting the sepsis syndrome. This observation has been used to infer the presence of occult tissue or organ ischemia that potentially can be eradicated by augmenting DO2. We examined this hypothesis by determining the VO2-DO2 relationship and lactate metabolism in the splanchnic region. DESIGN: Before and after intervention trial. SETTING: University-affiliated Veterans Affairs Medical Center, Allen Park, Mich. PATIENTS: Eighteen surgical patients exhibiting the sepsis syndrome. INTERVENTION: Systemic and splanchnic oxygen exchange and lactate uptake measurements before and after augmentation of DO2 with blood transfusion. MAIN OUTCOME MEASURES: Changes in oxygen exchange and lactate metabolism. RESULTS: The splanchnic VO2 index rose 9% in association with a 26% regional DO2 index increase indicating an oxygen transport dependency (P < .05). Splanchnic O2 extraction (0.47 +/- 0.04) was significantly greater than the mean systemic level (0.31 +/- 0.02) and showed a greater decline following DO2 index augmentation (0.41 +/- 0.04 vs 0.28 +/- 0.03, respectively). However, splanchnic lactate uptake was not changed significantly in response to the increased DO2 index. CONCLUSIONS: Although splanchnic oxygen transport dependency and elevated extraction ratios suggest the presence of regional ischemia that should be relieved with an increased DO2 index, the observed changes in lactate uptake do not support this conclusion. The significance of the VO2-DO2 relationship, its role in the pathophysiology of the sepsis syndrome, and its place in the clinical care of the septic surgical patient are in doubt.

Endoscopic management of nonvariceal gastrointestinal bleeding.

Endoscopic management of upper gastrointestinal bleeding has been expanded from a purely diagnostic role to a therapeutic role in many patients. In addition to controlling active bleeding, it is an option in a patient who is clinically at a high risk of rebleeding, or in patients who have peptic ulcers with visible vessels or stigmata indicating high risk. Several methods have been studied, and currently the most useful include thermal cautery with the heater probe or bipolar electrocoagulation, and injection using epinephrine and/or sclerosants. Endoscopic hemostasis can effect permanent control of bleeding in many patients, but should be considered complementary to conventional surgical control in other patients, where temporary control to stabilize the patient is a desired end.

Is preoperative parenteral nutrition necessary for patients with predominantly ileal Crohn's disease?

We reviewed 46 consecutive patients with Crohn's disease predominantly affecting the ileum who specifically underwent right-sided ileocolectomy with primary anastomosis. All had a primary ileocolic anastomosis done by suture in a single-layer closed fashion. Of these 46 patients, 19.6% had overt intra-abdominal sepsis, 30.4% had prior surgery, and 95.7% were taking corticosteroid drugs just before their operation. The mean (+/- SE) age was 31.5 +/- 2.0 years. The serum albumin level was less than 35 g/L in 93.5% of patients; all had a hematocrit value less than 0.36, and 80.4% lost more than 15% of their normal body weight. No patient received parenteral nutrition either preoperatively or postoperatively. No change in the preoperative, intraoperative, or postoperative approach to treating patients with predominantly ileal Crohn's disease occurred during the 10-year period of review. There was a 2.2% incidence of perioperative complications (one superficial wound infection) and a 6.5% incidence of late (>1.49 months) complications (two suture sinuses and one wound abscess unassociated with a fistula). Our findings suggest that preoperative parenteral nutrition is unnecessary in the majority of patients with predominantly ileal Crohn's disease specifically undergoing right-sided ileocolectomy and primary ileocolic anastomosis.

The lysP gene encodes the lysine-specific permease.

Escherichia coli transports lysine by two distinct systems, one of which is specific for lysine (LysP) and the other of which is inhibited by arginine ornithine. The activity of the lysine-specific system increases with growth in acidic medium, anaerobiosis, and high concentrations of lysine. It is inhibited by the lysine analog S-(beta-aminoethyl)-L-cysteine (thiosine). Thiosine-resistant (Tsr) mutants were isolated by using transpositional mutagenesis with TnphoA. A Tsr mutant expressing alkaline phosphatase activity in intact cells was found to lack lysine-specific transport. This lysP mutation was mapped to about 46.5 min on the E. coli chromosome. The lysP-phoA fusion was cloned and used as a probe to clone the wild-type lysP gene. The nucleotide sequence of the 2.7-kb BamHI fragment was determined. An open reading frame from nucleotides 522 to 1989 was observed. The translation product of this open reading frame is predicted to be a hydrophobic protein of 489 residues. The lysP gene product exhibits sequence similarity to a family of amino acid transport proteins found in both prokaryotes and eukaryotes, including the aromatic amino acid permease of E. coli (aroP) and the arginine permease of Saccharomyces cerevisiae (CAN1). Cells carrying a plasmid with the lysP gene exhibited a 10- to 20-fold increase in the rate of lysine uptake above wild-type levels. These results demonstrate that the lysP gene encodes the lysine-specific permease.

Blood transfusion and oxygen consumption in surgical sepsis.

OBJECTIVE: To evaluate the use of serum lactic acid values to predict flow-dependent increases in oxygen consumption (VO2) in response to increasing oxygen delivery (DO2) after blood transfusion in surgical sepsis. DESIGN: Prospective study. SETTING: Tertiary care, trauma center. PATIENTS: Twenty-one patients, postsurgical or posttrauma, judged septic by defined criteria. INTERVENTIONS: Serum lactic acid concentrations, DO2, and VO2 were measured before and after transfusion therapy. MEASUREMENTS AND MAIN RESULTS: Overall, the DO2 increased from 532 +/- 146 to 634 +/- 225 (SD) mL/min.m2 (p less than .001), and the VO2 increased from 145 +/- 39 to 160 +/- 56 mL/min.m2 (p = .02). These changes occurred with an Hgb increase from 9.3 +/- 1.1 to 10.7 +/- 1.5 g/dL (p less than .001). The patients were grouped by their pretransfusion serum lactic acid values. In those patients with normal (less than 1.6 mmol/dL) serum lactic acid (n = 10), DO2 increased from 560 +/- 113 to 676 +/- 178 mL/min.m2 (p less than .02), and VO2 increased from 150 +/- 25 to 183 +/- 46 mL/min.m2 (p less than .02). However, in the increased serum lactic acid group (n = 17), VO2 was not significantly changed after transfusion (143 +/- 46 to 146 +/- 58 mL/min.m2) despite increased DO2 (515 +/- 163 to 609 +/- 251 mL/min.m2, p less than .01). CONCLUSIONS: Blood transfusion can be used to augment DO2 and VO2 in septic surgical patients. Increased serum lactic acid values do not predict patients who will respond. The absence of lactic acidosis should not be used in this patient population to justify withholding blood transfusions to improve flow-dependent VO2. Patients who have increased lactate concentrations may have a peripheral oxygen utilization defect that prevents improvement in VO2 with increasing DO2.

Upper GI bleeding in an urban hospital. Etiology, recurrence, and prognosis.

Acute upper gastrointestinal bleeding (UGIB) continues to be a common cause of hospital admission and morbidity and mortality. This study reviews 469 patients admitted to a surgical service of an urban hospital. There were 562 total admissions because 53 patients were readmitted 93 times (recurrence rate, 20%). The most common causes of bleeding, all endoscopically diagnosed, included acute gastric mucosal lesion (AGML) (135 patients, 24%), esophageal varices (EV) (121 patients, 22%), gastric ulcer (108 patients, 19%), duodenal ulcer (78 patients, 14%), Mallory-Weiss tear (61 patients, 11%), and esophagitis (15 patients, 3%). Nonoperative therapy was sufficient in 504 cases (89.5%). Endoscopic treatment was used in 144 cases. Operations were performed in 58 cases (10.5%), including 29% of ulcers. Emergency operations to control hemorrhage were required in only 2.5% of all cases. The rate of major surgical complications was 11% and the mortality rate was 5.2%. There were 58 deaths (12.6%), with 36 deaths directly attributable to UGIB. Factors correlating with death include shock at admission (systolic blood pressure less than 80), transfusion requirement of more than five units, and presence of EV (all p less than 0.001). Most cases of UGIB can be treated without operation, including endoscopic treatment, when diagnostic endoscopy establishes the source. Subsequent operation in selected patients can be done with low morbidity and mortality rates.