The front-line general surgery consultant as a new model of emergency care.

Introduction Emergency general surgery services in England are undergoing rapid structural change with the aim of improving care. In our centre, the key issues identified were high numbers of admissions, inappropriate referrals, prolonged waiting times, delayed senior input and poor patient satisfaction. A new model was launched in January 2015 to address these issues: the surgical triage unit (STU). This study assesses the success of the new service. Methods All emergency general surgical admissions during a five-month period before introduction of the STU were compared with those of a comparable five-month period after its introduction. Process, clinical and patient experience outcomes were assessed to identify improvement. Results Attendance fell from 3,304 patients in the 2014 cohort to 2,830 in the 2015 cohort. During the 2015 study period, 279 more patients were discharged on the same day. Resource requirement fell by 2,635 bed days (23%). The number of true surgical emergencies remained consistent. Rates for reattendance (7.8% for 2014 vs 8.1% for 2015) and readmission (5.7% for 2014 vs 5.7% for 2015) showed no significant difference. Patient experience data demonstrated a significant improvement in both net promoter score (64.1 vs 82.2) and number of complaints (34 vs 5). Clinical outcomes for low risk procedures remained similar. Emergency laparotomy in-hospital mortality fell (11.4% vs 10.3%) despite preoperative risk stratification suggesting a risk burden that was significantly higher than the national average. Conclusions This novel model of emergency general surgery provision has improved clinical efficiency, patient satisfaction and outcomes. We encourage other units to consider similar programmes of service improvement.

Postoperative survival following perioperative MAGIC versus neoadjuvant OE02-type chemotherapy in oesophageal adenocarcinoma.

The optimal management of resectable oesophageal adenocarcinoma is controversial, with many centres using neoadjuvant chemotherapy following the Medical Research Council (MRC) oesophageal working group (OE02) trial and the MRC Adjuvant Gastric Infusional Chemotherapy (MAGIC) trial. The more intensive MAGIC regimen is used primarily in gastric cancer but some also use it for oesophageal cancer. A database of cancer resections (2001-2013) provided information on survival of patients following either OE02 or MAGIC-type treatment. The data were compared using Kaplan-Meier analysis. Straight-to-surgery patients were also reviewed and divided into an 'early' cohort (2001-2006, OE02 era) and a 'late' cohort (2006-2013, MAGIC era) to estimate changes in survival over time. Subgroup analysis was performed for responders (tumour regression grade [TRG] 1-3) versus non-responders (TRG 4 and 5) and for anatomical site (gastro-oesophageal junction [GOJ] vs oesophagus). An OE02 regimen was used for 97 patients and 275 received a MAGIC regimen. Those in the MAGIC group were of a similar age to those undergoing OE02 chemotherapy but the proportion of oesophageal cancers was higher among MAGIC patients than among those receiving OE02 treatment. MAGIC patients had a significantly lower stage following chemotherapy than OE02 patients and a higher median overall survival although TRG was similar. On subgroup analysis, this survival benefit was maintained for GOJ and oesophageal cancer patients as well as non-responders. Analysis of responders showed no difference between regimens. 'Late' group straight-to-surgery patients were significantly older than those in the 'early' group. Survival, however, was not significantly different for these two cohorts. Although the original MAGIC trial comprised few oesophageal cancer cases, our patients had better survival with MAGIC than with OE02 chemotherapy in all anatomical subgroups, even though there was no significant change in operative survival over the time period in which these patients were treated. The use of the MAGIC regimen should therefore be encouraged in cases of operable oesophagogastric adenocarcinoma.

Sarcopenia is associated with toxicity in patients undergoing neo-adjuvant chemotherapy for oesophago-gastric cancer.

BACKGROUND: Patients with potentially curative oesophago-gastric cancer typically undergo neo-adjuvant chemotherapy prior to surgery. The majority of anti-cancer drugs have a narrow therapeutic index. The aim of this study was to determine if features of body composition, assessed using computed tomography (CT) scans, may be predictive of dose-limiting toxicity (DLT) in patients undergoing neo-adjuvant chemotherapy for oesophago-gastric cancer. The influence of sarcopenia and DLT on overall survival was also evaluated. METHODS: 89 Patients having potentially curative oesophago-gastric cancer surgery were studied. Patients studied had histologically confirmed oesophago-gastric cancer with no evidence of distant metastasis on pre-operative staging. CT scan was performed in all cases at diagnosis. DLT was defined as toxicity leading to postponement of treatment, a drug dose reduction or definitive interruption of drug administration. RESULTS: DLT occurred in 37 out of 89 patients (41.6%) undergoing chemotherapy. Sarcopenia (odds ratio, 2.95; 95% confidence interval, 1.23-7.09; p = 0.015) was associated with DLT on multivariate analysis. Median overall survival for patients who were sarcopenic was 569 days (IQ range: 357-1230 days) vs. 1013 days (IQ range: 496-1318 days) for patients who were not sarcopenic (p = 0.04). There was no significant difference in overall survival in patients who experienced DLT compared with those that did not (p = 0.665). CONCLUSIONS: Sarcopenia is a significant predictor of DLT in oesophago-gastric cancer patients undergoing neo-adjuvant chemotherapy. These results raise the potential for use of assessment of skeletal muscle mass using CT scans to predict toxicity and individualize chemotherapy dosing.

Reduction in length of stay for patients undergoing oesophageal and gastric resections with implementation of enhanced recovery packages.

INTRODUCTION: The high mortality and morbidity associated with resection for oesophagogastric malignancy has resulted in a conservative approach to the postoperative management of this patient group. In August 2009 we introduced an enhanced recovery after surgery (ERAS) pathway tailored to patients undergoing resection for oesophagogastric malignancy. We aimed to assess the impact of this change in practice on standard clinical outcomes. METHODS: Two cohorts were studied of patients undergoing resection for oesophagogastric malignancy before (August 2008 - July 2009) and after (August 2009 - July 2010) the implementation of the ERAS pathway. Data were collected on demographics, interventions, length of stay, morbidity and in-hospital mortality. RESULTS: There were 53 and 55 oesophagogastric resections undertaken respectively for malignant disease in each of the study periods. The median length of stay for both gastric and oesophageal resection decreased from 15 to 11 days (Mann-Whitney U, p<0.001) following implementation of the ERAS pathway. There was no significant increase in morbidity (gastric resection 23.1% vs 5.3% and oesophageal resection 25.9% vs 16.7%) or mortality (gastric resection no deaths and oesophageal resection 1.8% vs 3.6%) associated with the changes. There was a significant decrease in the number of oral contrast studies used following oesophageal resection, with a reduction from 21 (77.8%) in 2008-2009 to 6 (16.7%) in 2009-2010 (chi-squared test, p<0.0001). CONCLUSIONS: The introduction of an enhanced recovery programme following oesophagogastric surgery resulted in a significant decrease in length of median patient stay in hospital without a significant increase in associated morbidity and mortality.

Traditional AMPA receptor antagonists partially block Na v1.6-mediated persistent current.

Voltage-gated Na channels and AMPA receptors play key roles in neuronal physiology. Moreover, both channels have been implicated in the pathophysiology of both grey and white matter in a variety of conditions. Dissecting out the roles of these channels requires specific pharmacological tools. In this study we examined the potential non-specific effects on Na(v)1.6 channels of five widely used AMPA receptor blockers. Using whole-cell patch clamp electrophysiology, we identified a TTX-sensitive persistent Na channel current in HEK cells stably expressing the Na(v)1.6 channel. From a holding potential of -120 mV, slow ramp depolarization to +75 mV generated an inward current that peaked at approximately -15 mV. Superfusion of purportedly specific AMPA antagonists, 1-naphthylacetyl spermine, SYM2206, CP465022, GYKI52466, blocked Na(v)1.6-mediated persistent currents in a dose-dependent manner. Each of these AMPA receptor blockers significantly inhibited (to approximately 70% of control levels) the persistent Na current at concentrations routinely used to selectively block AMPA receptors. The AMPA/kainate blocker, NBQX, did not significantly affect persistent Na channel currents. Furthermore, peak transient current was insensitive to NBQX, but was reversibly inhibited by SYM2206, CP465022 and GYKI52466. These results indicate that many commonly used AMPA receptor antagonists have modest but significant blocking effects on the persistent components of Na(v)1.6 channel activity; therefore caution should be exercised when ascribing actions to AMPA receptors based on use of these inhibitors.

Gastrointestinal stromal tumours (GIST) - 17 years experience from Mid Trent Region (United Kingdom).

OBJECTIVES: To report our experience with gastrointestinal stromal tumours (GISTs). METHODS: Retrospective data were collected from January 1987 to December 2003. Clinical and histological data were analysed to identify recurrence patterns and factors predicting survival. The tumours were studied with respect to size, number of mitosis and cell type. RESULTS: One hundred and eighty-five patients were identified with GIST with the age range of 18-93 years (mean 64.4 years) with a mean follow up of 6.7 years. Eighty out of 185 patients were in the low group, 38/185 in intermediate risk and 67/185 were in the high risk group. Eighty-three percent of the patients underwent surgical resection. Ten percent of the patients in the intermediate group and 25% of the patients in high risk group developed recurrence. Mortality was 5% and 37% in intermediate and high risk groups, respectively. There was no tumour related mortality or recurrence in the low risk group. CONCLUSIONS: It is important to identify the patients in low and high risk groups. Patients in intermediate and high risk groups require complete resection (R0) and follow up with CT scans.

Esophagogastric cancers secondary to a breast primary tumor do not require resection.

BACKGROUND: Breast cancer metastasis to the gastrointestinal tract (GIT) is rare. When it does occur, the upper GIT is more frequently involved, and lobular infiltrating carcinoma apparently has a greater apparent predilection for the GIT than the ductal type does. This study reviewed the clinicopathological features of esophagogastric secondary tumors from breast cancer. PATIENTS AND METHODS: Patients with breast cancer metastases to the upper GIT referred to us for treatment of either esophageal or gastric cancers between November 1997 and November 2004 were identified from our database. The medical records of these patients were then reviewed for clinicopathological data and outcome. RESULTS: Nine patients with mean age of 71 (range: 57-90) years had median time of 6.5 (2.8-32.8) years between primary breast cancer diagnosis and upper GI metastasis. The sites of metastatic lesions included the lower esophagus (2 patients), gastroesophageal junction (1 patient), gastric body (3 patients), and pylorus (3 patients). Histological typing indicated 7 cases of the lobular form and 2 cases of ductal carcinoma. All but one biopsy specimen were estrogen receptor and CK7 positive. Treatment included hormonal therapy and stent in 3 patients, hormonal therapy alone in 1 patient, chemotherapy alone in 1 patient, chemotherapy and gastrojejunostomy in 1 patient, dilatation and stent in 1 patient, and palliative care only in 2 patients. The median survival following treatment of these metastases was 20 (range: 2.1-96.6) months. CONCLUSIONS: The onset of nonspecific GIT symptoms in patients with a history of breast carcinoma should prompt the clinician to rule out the possibility of upper GIT metastasis even many years after the original breast cancer. The use of systemic therapy for breast cancer may result in longer survival.

The role of staging laparoscopy in oesophagogastric cancers.

AIMS: Selection of patients for treatment of oesophagogastric cancers rests on accurate staging. Laparoscopy has become a safe and effective staging tool in upper gastrointestinal cancers because of its ability to detect small peritoneal and liver metastases missed by imaging techniques. The aim of this study was to evaluate the role of staging laparoscopy (SL) in determining resectability of oesophagogastric cancers. METHODS: A review of 511 patients with oesophagogastric cancers referred to our centre during a 7-year period was performed. Four hundred and sixteen of them assessed to have resectable tumours after preoperative staging with CT and/or ultrasound underwent SL. The main outcome measure was the number of patients in whom laparoscopy changed treatment decision. RESULTS: Staging laparoscopy changed treatment decision in 84 cases (20.2%): locally advanced disease in 17, extensive lymph node disease in four and distant metastases (liver and peritoneum) in 63 cases. The sensitivity of laparoscopy for resectability was 88%. Eighty-one percent of patients who had combined CT scan and EUS were resectable at surgery compared with 65% of those who had CT scan alone (statistically significant with P-value<0.05). Of those patients deemed resectable by SL 8.1% were found to be unresectable at laparotomy, 16 with locally advanced disease and 11 with metastases. CONCLUSION: Staging laparoscopy avoided unnecessary laparotomy in 20.2% of our patients and was most useful in adenocarcinoma, distal oesophageal, GOJ and gastric cancers and probably not necessary in lesions of the upper two-third of the oesophagus.

A survey of patient satisfaction and use of the Internet for health information.

To survey patients/carers' use of the Internet and other sources for health information, to determine how useful health information over the Internet was to patients/carers and to assess the potential use of validated health information on the Internet by our patients. A multidisciplinary questionnaire survey of the use of the Internet for health information was performed. The study population consisted of patients and accompanying adults 18 years and older who attended outpatient clinics at Nottingham City Hospital for a period of two weeks in July 2005. The questionnaire captured information on demographics, frequency of use of the Internet, sources of health information, satisfaction rating of health information obtained on the Internet and their interest in using trustworthy health information Internet site if made available. Of the 800 questionnaires sent out, 663 responded (83%). Sixty three percent of patients had access to the Internet. 42% of the participants had used the Internet to access health information prior to this survey. 7.5% of the participants who have no access to the Internet, have had someone else look up health information on the Internet on their behalf. 95% of the respondents who had used the Internet for health information rated such information between average to excellent. 82% of those with Internet access and 21% of those with no Internet access would be interested in using trustworthy health information on the internet. Nearly half of our population of secondary care patients have used the internet to access health information and most are interested in using validated health information. Delivery of validated health information via the internet should be a priority for health care providers.

A phase II study of G17DT in gastric carcinoma.

PURPOSE: G17DT is a gastrin immunogen, raising antibodies that blockade gastrin-stimulated growth. The aim of the study was to characterise antibody response and assess safety and tolerability of G17DT given to patients with gastric cancer. EXPERIMENTAL DESIGN: G17DT was administered to 52 patients with gastric adenocarcinoma at weeks 0, 2 and 6 by intramuscular injection at doses of 10, 100 and 250 microg. Antibody levels were measured by an ELISA assay. A radioligand displacement assay determined the ability of G17DT-immunised patients' sera to inhibit binding of 125IG17 to cholecystokinin (CCK)-2 receptors. RESULTS: By week 12 of the study, 6/12 evaluable stage I-III patients achieved an antibody response in the 10 microg group, 7/11 in the 100 microg group, and 11/12 in the 250 microg group. Stage IV patients dosed at 250 microg achieved a similar response rate to stage I-III patients dosed at 10 or 100 microg. G17DT was well tolerated in 47/52 patients. Two patients suffered significant adverse reactions including injection site pain and abscess. G17DT antibodies displaced iodinated gastrin from CCK-2 receptors, with the level of displacement correlating with antibody titre. CONCLUSIONS: G17DT immunisation is a well-tolerated method of raising functional antibodies to 17 amino acid gastrin forms in patients with gastric carcinomas.

Risk as feelings.

Virtually all current theories of choice under risk or uncertainty are cognitive and consequentialist. They assume that people assess the desirability and likelihood of possible outcomes of choice alternatives and integrate this information through some type of expectation-based calculus to arrive at a decision. The authors propose an alternative theoretical perspective, the risk-as-feelings hypothesis, that highlights the role of affect experienced at the moment of decision making. Drawing on research from clinical, physiological, and other subfields of psychology, they show that emotional reactions to risky situations often diverge from cognitive assessments of those risks. When such divergence occurs, emotional reactions often drive behavior. The risk-as-feelings hypothesis is shown to explain a wide range of phenomena that have resisted interpretation in cognitive-consequentialist terms.

Researching the rural-metropolitan health differential using the 'social determinants of health'.

Recent research indicates that the health status of rural people is inferior to that of people living in metropolitan Australia. This paper summarises the rural-metropolitan health differential and turns to the field of research being called the social determinants of health for explanations of rural health inequalities. The paper explores the ways in which psychosocial factors can interact with material, behavioural and sociocultural factors to contribute to health outcomes. It suggests that the concepts of place and rurality may be useful in future research on the determinants of population health. Further research issues are identified that need to be addressed if we are to understand the complexities of rural health disadvantage.

Surveillance for Barrett's oesophagus in the UK.

BACKGROUND: Endoscopic screening for Barrett's oesophagus is being offered without evidence of efficacy Barrett's oesophagus is not an ideal candidate for a screening programme, as the natural history is unclear, uncertainties surround the indication for intervention and the treatment is associated with high morbidity and mortality rates. METHODS: To determine the practices that clinicians employ in the management of Barrett's oesophagus in the UK, postal questionnaires were sent in May 1997 to 297 randomly selected members of the British Society of Gastroenterology asking for details of their current practice. RESULTS: Of 152 respondents, 106 (70 per cent) performed surveillance for Barrett's oesophagus; 46 (30 per cent) did not carry out screening. There was no difference in the practices carried out by physicians or surgeons, teaching or acute general hospital clinicians, or those with an upper gastrointestinal interest. There was a wide disparity in screening interval: just over half (52 per cent) screen at yearly intervals. Only nine (8 per cent) took four quadrant biopsies per 2 cm of Barrett's oesophagus. Nearly half (49 per cent) manage mild dysplasia by increasing the frequency of endoscopy; only seven (7 per cent) prescribed patients a proton pump inhibiting agent. Faced with severe dysplasia, 33 (31 per cent) offered surgery immediately; 22 (21 per cent) simply followed the patient by endoscopy. Those not choosing to perform screening most frequently cited lack of evidence of efficacy as the reason behind their decision. CONCLUSION: There is wide variation in surveillance practices for Barrett's oesophagus. Some methods are ineffectual. The recommendations made by the Barrett's Oesophagus Working Party in 1991 are not followed, possibly because they are not practical. New workable guidelines based on available evidence and a consensus of expert opinion should be established; this was suggested by 38 per cent of respondents who performed screening.

First Report of Blossom Blight of Strawberry Caused by Xanthomonas fragariae and Cladosporium cladosporioides in California.

In the spring of 1996, severe blossom blight occurred in some strawberry fruit production fields in the Watsonville area. The symptoms, in addition to blighting of entire flowers, were as follows: on the lower surface of the calyx, watersoaked lesions that appeared dark green under reflected light and translucent under transmitted light; necrotic calyces of seemingly healthy green and ripe fruits; watersoaking of the base of the calyx that extended into the pedicel; green-gray sporulation on dead anthers; and presence of flower clusters with small and irregularly shaped fruits. Yellow bacterial colonies were consistently isolated from water-soaked and necrotic lesions on calyces and pedicels. These colonies were entire, circular, raised, glistening, mucoid, and slow growing, characteristics typical of Xanthomonas fragariae on nutrient agar-glucose-yeast extract medium. The bacterial isolate was also identified by rep-polymerase chain reaction as X. fragariae. In addition to the yellow bacteria, a fungus was also frequently isolated from infected anthers, sepals, petals, and pistils, and was identified as Cladosporium cladosporioides. On potato dextrose agar, the fungus had velvetlike colonies colored olivaceous-green to olivaceous-brown, apically and laterally branched conidiophores, and lemon-shaped conidia that were usually smooth but sometimes textured. Blossoms of greenhouse-grown strawberry plants cv. Selva were inoculated with either or both organisms. Blossoms inoculated with X. fragariae developed symptoms distinct from those inoculated with C. cladosporioides. The most prominent visible symptoms caused by X. fragariae were watersoaked lesions on calyces that later became necrotic, watersoaking of the calyx that extended into the pedicel, and blighting of flowers and developing fruits as a result of girdling of the pedicel. Infection by C. cladosporioides was characterized by necrosis of flower parts or the entire flower, presence of green-gray sporulation on dead anthers, and production of small and malformed or misshapen fruits. Inoculation with both organisms produced all the symptoms described above in different flowers of a plant. Infection with both organisms aggravated disease severity, but each organism was capable of inducing blossom blight independently. Both organisms were reisolated from artificially inoculated strawberry flowers, fulfilling Koch's postulate for proof of pathogenicity. This is the first report of the two organisms causing blossom blight of strawberry in California. This is also the first report that C. cladosporioides is a pathogen of strawberry.

Selective propagation of retinal pericytes in mixed microvascular cell cultures using L-leucine-methyl ester.

Endothelial cell (EC) propagation has been simplified by developing cell-specific selection criteria. Methods commonly used for selectively isolating EC include: (i) differential sieving of disaggregated tissue, (ii) differential plating of cells on extracellular matrices, (iii) lectin affinity isolation of cell populations and (iv) fluorescence-activated cell sorting of cells labeled with a carbocyanine dye of acetylated low-density lipoprotein (DiI-Ac-LDL). Few criteria for selectively propagating pericytes (PC) are currently available. Nonspecific esterases exhibit a high degree of multiplicity when compared with other mammalian isozymes and may be suitable for the identification and selective propagation of cells of the microvasculature. Evaluation of esterase isotype expression in PC and EC by zymography indicates PC contain alpha-naphthyl acetate and alpha-naphthyl butyrate hydrolyzing esterases as well as dipeptidyl peptidase I, while EC only contain alpha-naphthyl acetate esterase. The cytotoxic response of PC and EC to various amino acid esters is assessed by monitoring vital dye uptake and by light microscopy. Several amino acid esters are cytotoxic to both cell types, whereas 50 mM L-leucine methyl ester (L-Leu OMe) is toxic to EC but not to PC. This amino acid ester is also toxic to mesothelial and retinal pigmented epithelial cells, other common contaminants of PC cultures. Analysis of protein composition by two-dimensional gel electrophoresis indicates that L-Leu OMe does not stimulate expression of stress response proteins in PC. Thus, L-Leu OMe can be utilized to cultivate PC selectively from mixed cell populations.

Expression and subcellular distribution of filamin isotypes in endothelial cells and pericytes.

Two principal forms of the actin binding protein, filamin, are expressed in mammalian cells: nonmuscle and muscle isotypes (FLN-1 and FLN-2). A protein that copurifies with an alpha-naphthyl acetate hydrolyzing esterase from human omentum microvessel endothelial cells (EC) is isolated by nondenaturing electrophoresis, sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and electroblotting. The purified protein is subjected to in situ trypsin cleavage, reversed-phase high performance liquid chromatography (HPLC) and automated Edman degradation. Six peptide fragments from the protein are identified to have 60-66% identity with nonmuscle filamin (ABP-280). Two of these peptides are 100% identical to a previously sequenced human muscle filamin fragment. Polyclonal antibody is produced using a 16-residue synthetic peptide corresponding to a structural beta-sheet region of muscle filamin. Compared with a variety of vascular cells evaluated, retinal pericytes express an abundance of both muscle and non-muscle filamin isotypes. Pericytes contain at least 10 times more muscle filamin than human umbilical vein EC and at least three times the amount expressed in human omentum microvessel and bovine pulmonary artery EC. Differential detergent fractionation indicates that both filamin isotypes are primarily localized in the cytosol and membrane/organelle fractions of pericytes. Another actin crosslinking protein, alpha-actinin, is primarily found in the cytosol and cytoskeletal fractions. The dynamic regulation of actin microfilament organization in pericytes may be controlled in part by the two filamin isotypes, which in turn may contribute to pericyte contractility.

Human omental microvascular endothelial and mesothelial cells: characterization of two distinct mesodermally derived epithelial cells.

Human omental microvascular endothelial (HOME) and mesothelial (MESO) cells share many phenotypic properties, but can be characterized from one another based upon a comprehensive panel of endothelial and mesothelial markers. Traditional cell markers such as von-Willebrand factor, DiI-Ac-LDL, and Ulex europaeus I lectin are not sufficient to distinguish between HOME and MESO cells. Furthermore, immunoreactivity to a panel of endothelial cell-specific monoclonal antibodies, including representatives from the known clusters of differentiation (CD), indicate that some of these antigens are coexpressed in HOME and MESO cells. In distinguishing between the two cell types, HOME and not MESO cells express E-selectin, E/P-selectin, P-selectin (CD62), Le-y, and VLA-6 (CDw49f*). Moreover, HOME cells and not MESO cells form tube-like structures when cultured on Matrigel. MESO cells differ from HOME cells based upon (1) the expression of cytokeratins; (2) their rapid proliferation in response to platelet-derived growth factor; and (3) a change from an epitheliod to fibroblast-like morphology in response to tumor necrosis factor and epidermal growth factor. Both HOME and MESO cells express tissue plasminogen activator and plasminogen activator inhibitor, but urokinase activity is only expressed by MESO cells. As there is no one universal endothelial or mesothelial cell marker that can specifically confirm the identity of these cells, it appears necessary to employ a comprehensive panel of cell markers to rule out the possibility of misidentifying a cell culture.

Two-stage isolation procedure for obtaining homogenous populations of microvascular endothelial and mesothelial cells from human omentum.

The human omentum is a highly vascularized tissue often advocated as a source of human microvascular endothelial (HOME) cells. The omentum also contains mesothelial (MESO) cells and isolation protocols published to date do not describe a separation of the two cell populations. Using a two-stage collagenase digestion procedure, homogenous populations of HOME and MESO cells are obtained from the same omental tissue sample. HOME and MESO cells are both simple squamous epithelial cells and consequently are often difficult to discriminate between based on morphology and reactivity with many of the conventional endothelial and mesothelial cell markers. Both HOME and MESO cells form typical cobblestone, contact-inhibited monolayers, metabolize DiI-Ac-LDL, and are immunoreactive to von Willebrand Factor and Ulex europeaus I lectin. However, MESO cells are distinguishable from HOME cells based upon their expression of cytokeratins. Moreover, HOME cells and not MESO cells form capillary-like structures when cultured on Matrigel. It appears that HOME and MESO cells share many phenotypic properties, but are distinguishable from one another based upon a comprehensive panel of endothelial and mesothelial markers. Both cell types should be useful for studying the biology and pathology of the human microvasculature in vitro.