A prospective randomized trial of cannulation technique in ERCP: effects on technical success and post-ERCP pancreatitis.

BACKGROUND AND STUDY AIMS: Inadvertent injection of contrast agent into the pancreatic duct is believed to be an important contributor to pancreatitis occurring after endoscopic retrograde cholangiopancreatography (post-ERCP pancreatitis, PEP). Our aim was to examine whether primary deep biliary cannulation with a guide wire is associated with a lower rate of PEP than conventional contrast-assisted cannulation. PATIENTS AND METHODS: From August 2003 to April 2006 all patients with an intact papilla who were referred for ERCP were eligible. Patients with pancreatic or ampullary cancer were excluded. Patients were randomized to undergo sphincterotomy biliary cannulation using either contrast injection or a guide wire. The ERCP fellow attempted initially for 5 minutes. If unsuccessful, the consultant attempted for 5 minutes using the same technique, followed by crossover to the other technique in the same sequence and then needle-knife sphincterotomy where appropriate. Patients were assessed clinically after the procedure, then followed up with telephone interviews after 24 hours and 30 days, and serum amylase and lipase tests after 24 hours. RESULTS: Out of 1654 patients undergoing ERCP, 413 were included in the study. PEP occurred in 29/413 (7.0 %): 16 in the guide-wire arm, 13 in the contrast arm ( P = 0.48). The overall cannulation success rate was 97.3 %. Cannulation was successful without crossover in 323/413 patients (78.2 %): 167/202 (81.4 %) in the guide-wire arm and 156/211 (73.9 %) in the contrast arm ( P = 0.03). Multivariate analysis demonstrated female sex (OR = 2.7, P = 0.04), suspected sphincter of Oddi dysfunction (OR = 5.5, P = 0.01), and complete filling of the pancreatic duct with contrast agent (OR = 3.5, P = 0.02) to be independently associated with PEP. The risk of PEP increased incrementally with each attempt at the papilla (OR 1.4 per attempt, P = 0.04) to greater than 10 % after four or more attempts. CONCLUSIONS: The guide-wire technique improves the primary success rate for biliary cannulation during ERCP but does not reduce the incidence of PEP compared to the conventional contrast technique. The incidence of PEP increases incrementally with each attempt at the papilla.

Argon plasma coagulation in the management of symptomatic gastrointestinal vascular lesions: experience in 100 consecutive patients with long-term follow-up.

BACKGROUND: The long-term efficacy of argon plasma coagulation (APC) in the management of gastrointestinal vascular lesions has not been evaluated in a large and well-defined series. The impact of APC on transfusion requirements and hemoglobin, and technical parameters including complications and number of treatment sessions, is assessed in this series. METHODS: Patients who underwent APC for bleeding gastrointestinal vascular lesions were identified via interrogation of an established endoscopic database, excluding patients with radiation proctitis, tumors, residual polypectomy tissue and acute ulcer bleeding. Follow-up data were collected via interview with patients and referring doctors, review of medical records, and follow-up blood tests. RESULTS: One hundred patients were enrolled, males = 46, median age = 74 yr (range: 19-99 yr). Median follow-up time was 16 months (range: 4-47 months). Lesions treated were arteriovenous malformations (n = 74) and gastric antral vascular ectasia (n = 26). Fifty-three patients required transfusion. In this group, median hemoglobin improved from 66 g/L (range: 35-114) to 111 g/L (range: 55-155, p < 0.001). Median transfusion velocity fell from 2 units/month (range: 0.1-6) to 0 units/month (range: 0-4, p < 0.001). Transfusion requirement was abolished in 77%. In non-transfusion-requiring patients, median hemoglobin improved from 105 g/L (range: 58-143) to 123 g/L (range: 79-158, p < 0.001). No complications occurred. CONCLUSIONS: APC is effective and safe in the management of gastrointestinal vascular lesions.

Sporadic duodenal adenoma is associated with colorectal neoplasia.

OBJECTIVE: The objective of this study was to assess the association between colorectal neoplasia and sporadic duodenal adenoma. METHODS: A retrospective case control study was conducted using the databases of two major teaching hospitals in Western Australia. The frequency of colorectal neoplasia in patients with sporadic duodenal adenomas was compared with that in a control group of patients presenting for endoscopies. The frequency of colorectal cancer in duodenal adenoma patients was also compared with the population incidence. RESULTS: Of 56 sporadic duodenal adenoma patients, 34 (61%) had been colonoscoped. When comparing the findings between patients with sporadic duodenal adenoma and an endoscoped control group, all colorectal neoplasias were significantly more common in the duodenal adenoma group (56% v 33%; odds ratio (OR) 2.4 (95% confidence intervals (CI) 1.1-5.4)). Although finding either advanced colorectal adenoma or cancer was also more common in duodenal adenoma patients (38% v 19%; OR 2.3 (95% CI 1.0-5.2)), as was finding colorectal cancer alone (21% v 8%; OR 3.0 (95% CI 1.0-9.1)), the results were not statistically significant. However, the incidence of colorectal cancer was much greater in duodenal adenoma patients than in the population (p<0.001). CONCLUSIONS: Sporadic duodenal adenoma has a clinically important association with colorectal neoplasia. Thus patients with duodenal adenomas should undergo colonoscopy to detect colorectal neoplasia.

Hospital efficiency and patient satisfaction.

The objective of this study was to investigate the relationship between efficiency and patient satisfaction for a sample of general, acute care hospitals in Ontario, Canada. A measure of patient satisfaction at the hospital level was constructed using data from a province-wide survey of patients in mid-1999. A measure of efficiency was constructed using data from a cost model used by the Ontario Ministry of Health, the primary funder of hospitals in Ontario. In accordance with previous studies, the model also included measures of hospital size, teaching status and rural location. Based on the results of this study, at a 95% confidence level, there does appear to be evidence to suggest that an inverse relationship between hospital efficiency and patient satisfaction exists. However, the magnitude of the effect appears to be small. Hospital size and teaching status also appear to affect satisfaction, with lower satisfaction scores reported among non-teaching and larger hospitals. This study did not find any evidence to suggest that hospital location (rural versus urban) or religious affiliation contributed to reports of patient satisfaction in any way not explained by the other measures included in the study. The findings imply that low patient satisfaction cannot be explained by excessive management concentration on efficiency. Managers should analyse some of the underlying causes of patient dissatisfaction before reconfiguring resources. It may be beneficial in larger hospitals to study the aspects of care that patients have reported they prefer in small hospitals.

Comparison of external and internal pelvic measurements of Belgian Blue cattle from sample herds in Belgium and the United kingdom.

Measurements describing pelvic conformation of pedigree Belgian Blue cows were obtained from a sample of nine herds in Flanders, Belgium, comprising 111 adult breeding cows, and from 11 herds in the United Kingdom comprising 108 similar cows. All herds in the Belgian sample (111 cows) managed parturition by elective caesarian section as did seven herds (56 cows) in the UK sample; the remainder of UK herds (52 cows) allowed cows the opportunity to calve naturally per vagina before resorting to caesarian section. The data described the external and internal measurements, and pelvic area characteristic of this breed, irrespective of the different selection pressures applied over a number of years to this breed through variation in farm management and market forces present in either country. From these data, generalized linear models were constructed to predict pelvic area; they correctly identified cows with either small or large pelvic areas. There were no significant differences in pelvic conformation between cattle bred either in Belgium or the UK, although those cows bred in herds where natural calving was allowed to take place had significantly larger internal pelvic height (p < 0.05) and area (p < 0.05) than other Belgian Blue cows. The correlation coefficients between internal pelvic height and width and external pelvic measurements were significant (p < 0.001). These results might facilitate the selection of breeding cows with larger pelvic area so that a higher proportion of cows can calve naturally than currently occurs. However, selection for other traits such as relatively low birth weight combined with higher weaning weight should be carried out at the same time.

Systemic administration of adrenomedullin(27-52) increases bone volume and strength in male mice.

Adrenomedullin is a 52-amino acid peptide first described in a human phaeochromocytoma but since been found to be present in many tissues, including the vascular system and bone. Because of its structural similarity to amylin and calcitonin gene-related peptide, both of which have actions on bone cells, we have previously assessed the effects of adrenomedullin on the skeleton, and found that it increases osteoblast proliferation in vitro and bone formation following local injection in vivo. The present study carries this work forward by assessing the effects on bone of the systemic administration of a fragment of this peptide lacking the structural requirements for vasodilator activity. Two groups of 20 adult male mice received 20 injections of human adrenomedullin(27-52) 8.1 microg or vehicle over a 4-week period and bone histomorphometry and strength were assessed. In the tibia, adrenomedullin(27-52) produced increases in the indices of osteoblast activity, osteoid perimeter and osteoblast perimeter (P<0.05 for both using Student's t-test). Osteoclast perimeter was not affected. There was a 21% increase in cortical width and a 45% increase in trabecular bone volume in animals treated with adrenomedullin(27-52) (P<0.002 for both). Assessment of bone strength by three-point bending of the humerus showed both the maximal force and the displacement to the point of failure were increased in the animals treated with adrenomedullin(27-52) (P<0.03 for both). There was also a significant increase in the thickness of the epiphyseal growth plate. No adverse effects of the treatment were noted. It is concluded that adrenomedullin(27-52) acts as an anabolic agent on bone. These findings may be relevant to the normal regulation of bone mass and to the design of agents for the treatment of osteoporosis.

Status migrainosus in children and adolescents.

Data concerning status migrainosus in children and adolescents is sparse. The varied clinical presentations, diagnostic evaluation, and treatment modalities are discussed.

Peptidyl diazomethyl ketones inhibit the human rhinovirus 3C protease: effect on virus yield by partial block of P3 polyprotein processing.

The efficacy of a series of diazomethyl ketones (DMKs) was measured in rhinovirus-infected cultures and against the HRV14 3C protease. Their specificity and potency were confirmed against purified recombinant enzyme expressed in a yeast secretion system. An internally quenched fluorescent peptide substrate was used to assess the potency against the enzyme, obtaining a 50% inhibitory concentration (IC50) of 1 microM for both Z-L-F-Q-CHN2 and Z-V-L-F-Q-CHN2, while a lower affinity was observed for Z-F-Q-CHN2. The tripeptide Z-L-F-Q-CHN2 blocked viral replication with an IC50 value of 30 microM as judged by the reduction in viral induced cytopathy of HeLa-H1 cells, as well as a marked reduction in viral plaque formation (50% effective concentration=20 microM). Western blot analysis of viral proteins from infected cells indicates that this inhibitor works specifically by blocking viral polyprotein maturation, displaying a reduction of detectable 3C protease and an accumulation of the 3CD polypeptide. These results indicate that DMK inhibitors of the 3C protease have antiviral potency. Furthermore, the pattern of viral protein processing observed suggests that reducing the concentration of mature HRV 3C protease even in the presence of increased 3CD protein is sufficient to block proper viral processing and significantly reduce virus yield.

Hydrochlorothiazide reduces loss of cortical bone in normal postmenopausal women: a randomized controlled trial.

PURPOSE: Thiazide diuretics reduce urine calcium excretion and might therefore reduce postmenopausal bone loss. In some, but not all, case-control studies, their use has been associated with a reduced incidence of hip fractures. We studied the effects of hydrochlorothiazide on bone loss in normal postmenopausal women. SUBJECTS AND METHODS: We performed a randomized, double-blind, 2-year trial of the effects of hydrochlorothiazide (50 mg per day) and placebo on bone mineral density in normal postmenopausal women. Participants were not required to have either low bone mineral density or hypertension. Bone mineral density was measured using dual-energy x-ray absorptiometry. RESULTS: One hundred eighty-five women entered the study, of whom 138 completed 2 years of follow-up. In an intention-to-treat analysis, hydrochlorothiazide produced significant benefits on bone mineral density of the total body (between-group difference at 2 years of 0.8%, 95% confidence interval [CI]: 0.3% to 1.3%, P <0.0001), legs (0.9%, 95% CI: 0.2% to 1.7%, P <0.0001), mid-forearm (1.2%, 95% CI: 0.2% to 2.2%, P = 0.02), and ultradistal forearm (1.7%, 95% CI: 0.1% to 3.2%, P = 0.04). There was no effect in the lumbar spine (0.5%, 95% CI: -0.5% to 1.6%) or femoral neck (0.2%, 95% CI: 1.3% to 1.7%). The between-group changes tended to be greatest during the first 6 months, except in the mid-forearm where there appeared to be a progressive divergence. An as-treated analysis produced similar results. Urine calcium excretion and indices of bone turnover decreased in the thiazide group, but parathyroid hormone concentrations did not differ between the groups. Treatment was tolerated well. CONCLUSIONS: Hydrochlorothiazide (50 mg per day) slows cortical bone loss in normal postmenopausal women. It may act directly on bone as well as on the renal tubule. The small size of the effect suggests that thiazides may have a role in the prevention of postmenopausal bone loss, but that they are not an appropriate monotherapy for treating osteoporosis.

Evidence for a major gene for bone mineral density in idiopathic osteoporotic families.

Although there have been a number of studies indicating a heritable component for osteoporosis in middle to late adulthood, the etiology of osteoporosis in young people is uncertain. The present study aims to evaluate the extent to which genetic factors influence familial resemblance for bone mineral density (BMD) in families ascertained on the basis of young osteoporotic probands. The sample comprises eight families (74 total individuals) that were identified through a proband under the age of 35 years with a history of two or more fractures and a spinal bone density of at least 2.5 SDs below the mean for age and sex (Z score). Secondary causes of osteoporosis were excluded in the probands. In total, 27% (18/66) of the probands' relatives had osteoporosis and an additional 30% (20/66) had osteopenia. Classical segregation analysis was performed to evaluate the extent to which a genetic etiology could account for familial resemblance in these families. The results indicate a major gene of codominant inheritance for spinal BMD. Model-fitting comparisons revealed no support for environmental effects or for polygenic inheritance.

Hormone replacement therapy causes a respiratory alkalosis in normal postmenopausal women.

Menopause is associated with an increase in venous bicarbonate concentrations that is reversible with hormone replacement therapy (HRT). However, the mechanism underlying this effect is not known. To address this question, we studied the changes in acid-base indexes in the arterialized venous blood of normal postmenopausal women commencing conjugated equine estrogen (0.625 mg/day), medroxyprogesterone acetate (MPA; 5 mg/day), their combination, or placebo, in a double blind randomized controlled study over 3 months. Serum bicarbonate concentrations decreased significantly in the groups receiving either MPA or estrogen plus MPA (P = 0.008). This trend was apparent as early as 2 days and reached 2.7 and 2.3 mmol/L in the respective groups by 3 months. Similar changes were seen with partial pressure of carbon dioxide (P = 0.04); a change of -0.7 kPa occurred in the estrogen plus MPA group at 3 months. There were no changes in bicarbonate concentrations or partial pressure of carbon dioxide in those receiving estrogen alone or placebo. Accompanying changes in blood pH were apparent in the estrogen plus MPA group, where there was an upward trend at 1 week (P = 0.056) and a significant change from baseline (+0.013) at 3 months (P = 0.03). In the whole group, the changes in pH were inversely correlated with those in urinary excretion of hydroxyproline (r = -0.44; P = 0.01). We conclude that HRT using conjugated estrogens and MPA produces small, but sustained, changes in acid-base status. These may contribute to the effects of HRT and menopause on many tissues and disease processes, including the development of osteoporosis.

Socioeconomic status and determinants of hemostatic function in healthy women.

Hemostatic factors are reported to be associated with coronary heart disease (CHD). Socioeconomic status (SES) is 1 of the determinants of the hemostatic profile, but the factors underlying this association are not well known. Our aim was to examine determinants of the socioeconomic differences in hemostatic profile. Between 1991 and 1994, we studied 300 healthy women, aged 30 to 65 years, who were representative of women living in the greater Stockholm area. Fibrinogen, factor VII mass concentration (FVII:Ag), activated factor VII (FVIIa), von Willebrand factor (vWF), and plasminogen activator inhibitor-1 (PAI-1) were measured. Educational attainment was used as a measure of SES. Low educational level and an unfavorable hemostatic profile were both associated with older age, unhealthful life style, psychosocial stress, atherogenic biochemical factors, and hypertension. Levels of hemostatic factors increased with lower educational attainment. Independently of age, the differences between the lowest (mandatory) and highest (college/university) education in FVII:Ag levels were 41 microg/L (95% confidence interval [CI], 15 to 66 microg/L, P=0.001), 0.26 g/L (95% CI, 0.10 to 0.42 g/L, P=0.001) in fibrinogen levels, and 0.11 U/mL (95% CI, 0.09 to 0.12 U/mL, P=0.03) in levels of vWF. The corresponding differences in FVIIa and PAI-1 were not statistically significant. With further adjustment for menopausal status, family history of CHD, marital status, psychosocial stress, lifestyle patterns, biochemical factors, and hypertension, statistically significant differences between mandatory and college/university education were observed in FVII:Ag (difference=34 microg/L; 95% CI, 2 to 65 microg/L, P=0.05) but not in fibrinogen (difference=0.03 g/L; 95% CI, -0.13 to 0.19 g/L, P=0.92) or in vWF (difference=0.06 U/mL; 95% CI, -0.10 to 0.22 U/mL, P=0.45). An educational gradient was most consistent and statistically significant for FVII:Ag, fibrinogen, and vWF. Age, psychosocial stress, unhealthful life style, atherogenic biochemical factors, and hypertension mediated the association of low educational level with elevated levels of fibrinogen and vWF. Psychosocial stress and unhealthful life style were the most important contributing factors. There was an independent association between education and FVII:Ag, which could not be explained by any of these factors.

Inhibitory effect of dibenzofuran and dibenzosuberol derivatives on rhinovirus replication in vitro; effective prevention of viral entry by dibenzosuberenone.

A series of derivatives of dibenzofuran and dibenzosuberol block rhinovirus replication in vitro as judged by their ability to hinder the cytopathic effect in cells infected with HRV14 or HRV16. Both the number and the size of viral plaques were reduced effectively by treatment with these compounds in a dose-dependent fashion, thus affecting viral spread. The compound 2-hydroxy-3-dibenzofuran carboxylic acid was equally effective against HRV16 and HRV14, with IC50 values of 25 microM in cytopathy assays. Dibenzosuberenone showed minor differences in selectivity, with IC50 values of 10 and 30 microM for HRV16 and HRV14 cytopathy, respectively. Likewise, dibenzosuberenone effectively prevented the production of HRV16 proteins, viral RNA, and infectious virus particles when present at concentrations above 30 microM. Time-of-addition experiments show that compounds must be administered before or during the viral adsorption step in order to be effective antivirals. Dibenzosuberenone can block the adsorption of viral particles on to cells, preventing further steps in the replication cycle, but is not effective as a direct inactivating agent. These compounds likely interact with viral capsid proteins, affecting receptor interactions required for attachment and subsequent entry into cells.

A genome-wide search for chromosomal loci linked to mental health wellness in relatives at high risk for bipolar affective disorder among the Old Order Amish.

Bipolar affective disorder (BPAD; manic-depressive illness) is characterized by episodes of mania and/or hypomania interspersed with periods of depression. Compelling evidence supports a significant genetic component in the susceptibility to develop BPAD. To date, however, linkage studies have attempted only to identify chromosomal loci that cause or increase the risk of developing BPAD. To determine whether there could be protective alleles that prevent or reduce the risk of developing BPAD, similar to what is observed in other genetic disorders, we used mental health wellness (absence of any psychiatric disorder) as the phenotype in our genome-wide linkage scan of several large multigeneration Old Order Amish pedigrees exhibiting an extremely high incidence of BPAD. We have found strong evidence for a locus on chromosome 4p at D4S2949 (maximum GENEHUNTER-PLUS nonparametric linkage score = 4.05, P = 5. 22 x 10(-4); SIBPAL Pempirical value <3 x 10(-5)) and suggestive evidence for a locus on chromosome 4q at D4S397 (maximum GENEHUNTER-PLUS nonparametric linkage score = 3.29, P = 2.57 x 10(-3); SIBPAL Pempirical value <1 x 10(-3)) that are linked to mental health wellness. These findings are consistent with the hypothesis that certain alleles could prevent or modify the clinical manifestations of BPAD and perhaps other related affective disorders.

Stickler syndrome without eye involvement is caused by mutations in COL11A2, the gene encoding the alpha2(XI) chain of type XI collagen.

Eye involvement has been considered a principal component feature in Stickler syndrome. However, families lacking eye involvement have been reported. We describe such a family and show that their phenotype is due to a heterozygous 27 basepair deletion in the gene COL11A2, which encodes the alpha2(XI) chain of type XI collagen. This is the second family in whom a COL11A2 mutation has been found to cause Stickler syndrome without eye involvement. This result confirms the role of COL11A2 in the etiopathogenesis of this disorder.

Evaluating expert systems: how to ensure an independent assessment.

Evaluation of an expert system provides unique challenges in an organizational setting. Often the proposed system is provided by an independent supplier who is not in a position to provide an unbiased assessment of the effectiveness or merit of the system. Even when the system is developed by personnel within the same firm or by the users themselves, these individuals, being instrumental in the design and development of the system, lack the autonomy necessary to evaluate the system. This article describes one evaluation process which was applied by the authors. It is an adaptable approach which provides the needed independent assessment without being excessively cumbersome or difficult to administer.

Determination of the genome composition of influenza virus reassortants using multiplex reverse transcription-polymerase chain reaction followed by fluorescent single-strand conformation polymorphism analysis.

The influenza virus genome is composed of eight negative-strand RNA segments. In cells coinfected with two or more influenza strains, the genomic RNAs reassort at random, resulting in progeny viruses (reassortants) that contain genes derived from each parent. Genetic reassortment among influenza viruses occurs naturally and plays an important role in viral epidemiology and pathogenicity. The reassortment process is also utilized for the annual production of influenza vaccines. Each year, the two gene segments that encode the major surface antigens of the current virulent, wild-type viruses are reassorted with the remaining six gene segments of a laboratory-derived vaccine or "master donor" strain. As the gene reassortment appears to be random, identifying a progeny virus with the desired gene constellation can be labor-intensive. We developed a streamlined, cost-effective method to genotype influenza viruses that combines multiplex reverse transcription-polymerase chain reaction (RT-PCR) and fluorescent single-strand conformation polymorphism (SSCP) analysis. This method utilizes oligonucleotide primers labeled with one of three fluorescent dyes to generate RT-PCR products for each gene segment in a multiplex configuration. The RT-PCR products of the reassortants, wild-type, and master donor viruses are then electrophoresed under SSCP conditions. The viral origin of each gene segment can be identified by fluorescence and mobility shift patterns of the corresponding RT-PCR products. We demonstrate the utility of this method in differentiating the genes of a master donor strain, several wild-type viruses, and vaccine reassortants.

Quality improvement in family practice. Program for Pap smears.

PROBLEM BEING ADDRESSED: With the increasing emphasis on quality improvement, we need programs for improving office practice. OBJECTIVE OF PROGRAM: To demonstrate a simple and inexpensive program that resulted in improvement in the quality of Papanicolaou smears in a family practice teaching clinic. The performance measure was the proportion of smears containing endocervical components. MAIN COMPONENTS OF PROGRAM: The program involved annual feedback on the performance of the physicians in the clinic. Feedback was given to physicians at a regular group meeting; brief discussion of the findings also occurred at that time. There were no other interventions. CONCLUSIONS: A program involving straightforward feedback and discussion for less than 1 hour contributed to a 7% improvement in the proportion of Pap smears with endocervical components. This "low tech" approach should be tested in other settings and with other procedures and treatments.

Developing microcomputer-based quality assurance systems for health care.

Points out some important issues that must be dealt with when developing microcomputer-based QA systems for health care. While no single solution to the problems associated with quality assurance (QA) system development exists, the first step towards an efficient and effective approach is problem identification and commitment to developing a strategy which addresses the issues discussed in this paper. Examines potential solution alternatives and associated pitfalls, and gives an example of designing a QA system, including a database management system with suggestions for spreadsheet templates.

Changing distributions of extracellular matrix components during early wing morphogenesis in Drosophila.

A new monoclonal antibody, specific to an epitope in the carboxyl terminus of the Drosophila collagen IV molecule (basement membrane collagen) was identified. The distributions of collagen IV, laminin, and an additional extracellular molecule, the 2G2 antigen (2G2-Ag), were followed immunocytochemically during early wing development. In late third instar larvae, collagen IV and laminin surround the entire wing disc, whereas the 2G2-Ag is limited to the region of the future wing pouch. For the first few hours following eversion of the disc, all three ECM components line the basal surfaces of all epithelial cells in the wing pouch, both those destined to line the wing veins and those destined to become tightly apposed in the large intervein regions. Collagen IV and laminin persist on these cells during the two initial rounds of apposition of dorsal and ventral wing surfaces; later, they become restricted to the cells lining the veins. The 2G2-Ag disappears completely quite early in the pupal period. Collagen IV appears to be synthesized at least twice, once in the larva and a second time in the pupa; in between it is enzymatically cleaved and may be eliminated, probably by hemocytes. In an extreme allele of blistered the wing is ballooned to form a single internal space. Collagen IV and laminin line all basal wing cell surfaces early in pupal development as they do in the wild type. Later, however, they continue to line the entire cavity of the mutant wing rather than assuming a restricted distribution. In a completely veinless wing (rhomboidveinletvein), collagen IV and laminin are also present generally on basal surfaces at early times, but are completely absent between the tightly apposed wing layers later. The ECM distributions both in wild type wings and in mutants suggest that the matrix plays a role in the establishment of the wing venation pattern. One possibility, strengthened by recent findings regarding ECM receptors in Drosophila, is their involvement in dorsal-ventral wing layer adhesion. Our findings also lead us to suggest that certain sets of features which distinguish vein from intervein cells may be linked during cell differentiation and thus help to define these cell phenotypes. The features include cytoskeletal specializations and certain cell surface and ECM molecules.