Finding meaning: a realist-informed perspective on social risk screening and relationships as mechanisms of change

Background

Social risk screening rates in many US primary care settings remain low. This realist-informed evaluation explored the mechanisms through which a tailored coaching and technical training intervention impacted social risk screening uptake in 26 community clinics across the United States.

Methods

Evaluation data sources included the documented content of interactions between the clinics and implementation support team and electronic health record (EHR) data. Following the realist approach, analysis was composed of iterative cycles of developing, testing and refining program theories about how the intervention did-or didn't-work, for whom, under what circumstances. Normalization Process Theory was applied to the realist program theories to enhance the explanatory power and transferability of the results.

Results

Analysis identified three overarching realist program theories. First, clinic staff perceptions about the role of standardized social risk screening in person-centered care-considered "good" care and highly valued-strongly impacted receptivity to the intervention. Second, the physicality of the intervention materials facilitated collaboration and impacted clinic leaders' perception of the legitimacy of the social risk screening implementation work. Third, positive relationships between the implementation support team members, between the support team and clinic champions, and between clinic champions and staff motivated and inspired clinic staff to engage with the intervention and to tailor workflows to their settings' needs. Study clinics did not always exhibit the social risk screening patterns anticipated by the program theories due to discrepant definitions of success between clinic staff (improved ability to provide contextualized, person-centered care) and the trial (increased rates of EHR-documented social risk screening). Aligning the realist program theories with Normalization Process Theory constructs clarified that the intervention as implemented emphasized preparation over operationalization and appraisal, providing insight into why the intervention did not successfully embed sustained systematic social risk screening in participating clinics.

Conclusion

The realist program theories highlighted the effectiveness and importance of intervention components and implementation strategies that support trusting relationships as mechanisms of change. This may be particularly important in social determinants of health work, which requires commitment and humility from health care providers and vulnerability on the part of patients.

Food Insecurity Screening in Primary Care: Patterns During the COVID-19 Pandemic by Encounter Modality

INTRODUCTION

Screening for food insecurity in clinical settings is recommended, but implementation varies widely. This study evaluated the prevalence of screening for food insecurity and other social risks in telehealth versus in-person encounters during the COVID-19 pandemic and changes in screening before versus after widespread COVID-19 vaccine availability.

METHODS

These cross-sectional analyses used electronic health record and ancillary clinic data from a national network of 400+ community health centers with a shared electronic health record. Food insecurity screening was characterized in 2022 in a sample of 275,465 first encounters for routine primary care at any network clinic during March 11, 2020-December 31, 2021. An adjusted multivariate multilevel probit model estimated screening prevalence on the basis of encounter mode (in-person versus telehealth) and time period (initial pandemic versus after vaccine availability) in a random subsample of 11,000 encounters.

RESULTS

Encounter mode was related to food insecurity screening (p<0.0001), with an estimated 9.2% screening rate during in-person encounters, compared with 5.1% at telehealth encounters. There was an interaction between time period and encounter mode (p<0.0001), with higher screening prevalence at in-person versus telehealth encounters after COVID-19 vaccines were available (11.7% vs 4.9%) than before vaccines were available (7.8% vs 5.2%).

CONCLUSIONS

Food insecurity screening in first primary care encounters is low overall, with lower rates during telehealth visits and the earlier phase of the COVID-19 pandemic. Future research should explore the methods for enhancing social risk screening in telehealth encounters.

Diffuse Large B Cell Lymphoma Raising Suspicion for an Infection: A Case Report

Newly discovered liver lesions have a broad differential ranging from malignancy to infection. While tissue biopsy is the gold standard diagnostic modality, imaging can also aid in diagnosis. Hepatocellular carcinoma (HCC) can be diagnosed via imaging alone; however, masses suspicious for infection ultimately require biopsy and culture. We report a case of a 72-year-old male who presented with subjective fever, nausea, decreased appetite, dark urine, elevated liver function tests, and CT evidence of an exophytic liver mass. Differentials included infections such as hepatobiliary actinomycosis, abscess, solid malignancy, or lymphoma. Obtaining a definitive diagnosis with tissue biopsy endoscopically and percutaneously was quite difficult due to the location of the lesion around the porta hepatis. Subsequent laparoscopic biopsy revealed diffuse large B cell lymphoma (DLBCL).

Quality Gaps in Management of Acute Pancreatitis: A Tertiary Care Center Experience

OBJECTIVES

Acute pancreatitis (AP) is a leading cause of inpatient care among gastrointestinal conditions. Our study compares the management of AP and adherence to guidelines among teaching medicine, nonteaching medicine, and surgical services within the same center.

METHODS

We performed a retrospective chart review of AP patients admitted to our center between January 2016 and January 2017 and analyzed the clinical and epidemiological data.

RESULTS

Of 115 patients, 65% were admitted to medicine (IM), and 35% were admitted to surgery. Mean age was 53.9 (standard deviation [SD], 15) years, and 52% were males; 38.6% (n = 29) of IM patients were prescribed lactated Ringer's solution for fluid resuscitation (mean rate of 153 [SD, 44.98] mL/h on teaching and 113 [SD, 43.56] mL/h on the nonteaching service). Antibiotics were prescribed to 22.6% (n = 17) of IM patients. On the surgical service, 77.5% of patients were prescribed lactated Ringer's solution for fluid resuscitation (mean rate of 108.25 [SD, 1.19] mL/h); 52.5% of patients received antibiotics.

CONCLUSIONS

Adherence to guidelines for management of AP is inadequate, and nonuniformity exists across different services within the same institution. There is a need for quality improvement initiatives.

Gastroenterology Fellowship Applicants' Perspectives on GI Program Preferences

Gastroenterology fellowship continues to be highly competitive among internal medicine subspecialties. Recruiting excellent applicants is also important for GI fellowship program directors. We aim to examine factors that influence GI fellowship applicants' perspectives about a fellowship program. The authors conducted an anonymous online survey of applicants focusing on program characteristics including location, faculty, research/clinical opportunities, website, and interview day experience. Anonymous survey responses were recorded regarding program characteristics, and subsequent candidate preferences were evaluated for factors influencing their decision. Candidates were also asked to evaluate their interview experience and share other comments about the program. Though GI fellowship applicants have varying preferences regarding the ideal training program, some opinions converged. The study of these trends can inform program directors regarding areas for improvement that in turn can help attract the best applicants.

Endoscopic ultrasound guided fine-needle aspiration vs core needle biopsy for solid pancreatic lesions: Comparison of diagnostic accuracy and procedural efficiency

BACKGROUND

Endoscopic ultrasound (EUS) guided core needle biopsies (CNB) are increasingly being performed to diagnose solid pancreatic lesions. However, studies have been conflicting in terms of CNB improving diagnostic accuracy and procedural efficiency vs fine-needle aspiration (FNA), which this study aims to elucidate.

METHODS

Data were prospectively collected on consecutive patients with solid pancreatic or peripancreatic lesions at a single tertiary care center from November 2015 to November 2016 that underwent either FNA or CNB. Patient demographics, characteristics of lesions, diagnostic accuracy, final and follow-up pathology, use of rapid on-site evaluation (ROSE), complications, and procedure variables were obtained.

RESULTS

A total of 75 FNA and 48 CNB were performed; of these, 13 patients had both. Mean passes were lower with CNB compared to FNA (2.4 vs 2.9, P = .02). Use of ROSE was higher for FNA (97.3% vs 68.1%, P = .001). Mean procedure time was shorter with CNB (34.1 minutes vs 51.2 minutes, P = .02) and diagnostic accuracy was similar (89.2% vs 89.4%, P = .98). There was no difference in diagnostic accuracy when ROSE was performed for CNB vs not performed (93.5% vs 85.7%, P = .58). Additionally, diagnostic accuracy of combined FNA and CNB procedures was 92.3%, which was comparable to FNA (P = .73) or CNB (P = .52) alone.

CONCLUSION

FNA and CNB had comparable safety and diagnostic accuracy. Use of CNB resulted in less number of passes and shorter procedure time as compared to FNA. Moreover, diagnostic accuracy for CNB with or without ROSE was similar.

Easy to swallow: detection of an extramural jejunal GIST by video capsule endoscopy

We report a case of a 57-year-old woman with an obscure gastrointestinal bleed who was found to have an extramural gastrointestinal stromal tumour (GIST), detected by capsule endoscopy, and confirmed by laparoscopically-assisted enteroscopy and resection. Currently, major modalities used for detection of GISTs include double-balloon enteroscopy, capsule endoscopy and CT. Endoscopic measures, including capsule endoscopy, are limited in their ability to detect GISTs with extramural growth, as these typically do not demonstrate obvious luminal abnormalities. This case report illustrates a case in which an extraluminal GIST causing recurrent gastrointestinal bleeding presented as an ulcer, as seen on capsule endoscopy.

Paediatric tracheostomy-An 11 year experience at a Scottish paediatric tertiary referral centre

AIMS

The aim of this paper was to review the indications, complications and outcomes for tracheostomy at a Scottish paediatric tertiary referral hospital.

METHODS

All patients undergoing tracheostomy between January 2001 and September 2012 were identified. A retrospective case note analysis was performed.

RESULTS

111 tracheostomies were done in the study period. The mean number per year was 11 (3-12). Full data was available for 95 patients. There were 56 (59%) males and 39 (41%) females. Age at time of tracheostomy ranged from one day to 15 years, the mean age of tracheostomy insertion was 69 weeks. The majority of patients, 75 (79%), were under one year old when they had their tracheostomy. The most common indication was long-term ventilation (20%), followed by craniofacial abnormality causing airway obstruction (18%), followed by subglottic stenosis (14%). 37% of patients were decannulated.

CONCLUSIONS

This series reflects current trends in the indications for paediatric tracheostomy, with chronic lung disease of prematurity being the most common indication.

Comparison of the outcomes of endoscopic ultrasound based on community hospital versus tertiary academic center settings

OBJECTIVE

Endoscopic ultrasound (EUS) is an established tool in the management of gastrointestinal diseases. The majority of EUS procedures are performed in tertiary care hospitals but the technology has also disseminated to community hospitals. The data from community hospitals are limited and there are no published studies comparing EUS-fine needle aspiration (FNA) outcomes in community versus tertiary settings. Our objective is to compare EUS procedures performed in these two separate settings.

METHODS

EUS procedures performed for pancreatobiliary indications in an academic tertiary care hospital and a community hospital were retrospectively reviewed and compared. The patient demographics, procedure time, procedure indications, FNA performed, pass counts, needle size, rapid onsite evaluation (ROSE) and final cytological diagnosis were compared between the two centers. Cytological diagnosis was categorized as satisfactory and unsatisfactory samples.

RESULTS

There was no significant difference in patient age, gender, indications, procedure time, FNA performed, needle size, or pass counts between the tertiary hospital (n = 361) and community hospital (n = 119). ROSE was a significant determinant factor for adequacy of sample. There was a positive linear relationship between adequacy of the sample and number of pass counts. After performing a logistic regression and adjusting for target site, the overall odds of having an unsatisfactory specimen were not significantly different at the two centers (OR 0.51, CI 0.23-1.17, p = 0.11). Percentages of unsatisfactory samples were not significantly different at the two centers for solid lesions (7.4 vs. 3.1%, p = 0.33), cysts (33.3 vs. 23.8%, p = 0.31,) or lymph nodes (25.0 vs. 0%, p = 0.063).

CONCLUSION

Cytological yield of EUS-FNA in a community hospital is similar to that of a tertiary hospital. Community hospitals can provide EUS services with reasonable success.

A phase I study of cabozantinib (XL184) in patients with renal cell cancer

BACKGROUND

Cabozantinib targets tyrosine kinases including the hepatocyte growth factor receptor (MET) and vascular endothelial growth factor (VEGF) receptor 2, which are important drug targets in renal cell carcinoma (RCC).

PATIENTS AND METHODS

This single-arm open-label phase I trial evaluated the safety and tolerability of cabozantinib in heavily pretreated patients with metastatic clear cell RCC.

RESULTS

The study enrolled 25 RCC patients for whom standard therapy had failed. Patients received a median of two prior systemic agents, and most patients had previously received at least one VEGF pathway inhibiting therapy (22 patients [88%]). Common adverse events included fatigue, diarrhea, nausea, proteinuria, appetite decreased, palmar-plantar erythrodysesthesia, and vomiting. Partial response was reported in seven patients (28%). Median progression-free survival was 12.9 months, and median overall survival was 15.0 months.

CONCLUSION

Cabozantinib demonstrates preliminary anti-tumor activity and a safety profile similar to that seen with other multitargeted VEGFR tyrosine kinase inhibitors in advanced RCC patients. Further evaluation of cabozantinib in RCC is warranted. ClinicalTrials.gov identifier: NCT01100619.

Global variability in diabetes mellitus and its association with body weight and primary healthcare support in 49 low- and middle-income developing countries

AIMS

In the absence of any previous global comparison, we examined the variability in prevalence of diabetes mellitus across 49 developing countries, and the associations of diabetes with body weight and primary healthcare support using data from the World Health Survey.

METHODS

Diabetes mellitus was defined by individuals' self-report of a physician diagnosis of diabetes. BMI is the weight (kg)/the square of the height (m). Healthcare support was assessed using clinical treatment status and whether patients with diabetes followed prescribed behaviour changes to control diabetes. Associations of diabetes with BMI and diabetes treatment status were analysed cross-sectionally.

RESULTS

A total of 215898 participants were included in the analysis. Age-adjusted prevalence of diabetes ranged from 0.27% (Mali) to 15.54% (Mauritius). Participants who were underweight (BMI <18.5 kg/m(2) ), overweight (BMI 25-29.9 kg/m(2) ) and obese (BMI ≥ 30 kg/m(2) ) were significantly associated with odds of having diabetes as compared with those who were of normal weight (BMI 18.5-24.9 k/m(2) ), with corresponding values of multivariate adjusted odds ratios (95% CI) of 1.15 (1.07-1.24), 1.56 (1.44-1.68) and 2.35 (2.17-2.61), respectively. The overall untreated rate of those with diabetes mellitus was 9.6% in the total sample. Patients with underweight had the highest diabetes untreated rate, followed by those with normal weight, overweight and obesity.

CONCLUSION

There are significant variations in prevalence of diabetes and primary healthcare support for diabetes across low- and middle-income countries. Aggressively preventing abnormal body weight and improving healthcare support may play a pivotal role in ameliorating the unfavourable epidemic of diabetes in developing countries.

Primary hepatic gastrinoma presenting as vague gastrointestinal symptoms

A 51-year-old Caucasian female with a 7-year history of intermittent abdominal pain and diarrhoea presented to our service. Before presentation, she had been successfully treated for Helicobacter pylori infection, but later developed new oesophageal ulcerations with exudative lesions that were positive for herpes simplex virus, and candida oesophagitis had developed. Biopsies showed chronic inactive gastritis with gastric intestinal metaplasia. MRI revealed a solid 3.4×3 cm lesion in the caudate lobe of the liver, with a 7-mm pancreatic cyst. The aspirated pancreatic cyst cytology was benign. On exploratory laporatomy, the lesion appeared confined to the caudate lobe, and a resection was performed. The pathology was consistent with a well-differentiated neuroendocrine carcinoma with vascular invasion and involvement of the liver capsule, although resection margins were negative. The patient had complete symptomatic improvement. This case re-affirms the high index of suspicion needed to make the diagnosis of gastrinoma. If caught in time, surgical removal of primary hepatic gastrinoma can be curative.

Abstract P5-14-03: The Impact of Routine Cavity Margins on Reducing the Need for Re-Excision in Women Undergoing Breast-Conserving Surgery for Invasive or Non-Invasive Breast Cancer

Background: The goal of breast conserving surgery (BCS) in women with invasive breast cancer (IBC) or ductal carcinoma in situ (DCIS) is to remove all malignant cells from the breast or to reduce the residual tumor burden to a level that is likely to be eradicated by adjuvant radiation therapy and/or systemic therapy. Theoretical concerns exist that radiography of lumpectomy specimens and subsequent pathologic processing may lead to artifactually positive lumpectomy margins (LM), and the need for subsequent re-excision. To improve the chances of obtaining negative final margins (FM) (generally defined as 2 mm or greater), a number of surgeons in the US and abroad have adopted a technique in which 4-6 additional margins surrounding the main lumpectomy specimen, so-called “cavity margins” (CM), are routinely obtained. The purpose of this study was to assess the clinical utility of the routine use of CM in reducing the need for re-excision.

Methods: The surgical pathology records at our institution were searched for all cases of BCS with additional complete routine CM sampling performed by a single surgeon between May 2008 and April 2010. Patients in whom additional CM were obtained based on intraoperative findings of grossly close margins were excluded from the analysis. The demographic characteristics of the patients and the histological features of the tumor were recorded. We then tabulated the number of patients who had positive LM, CM, and FM, defined as either DCIS or invasive carcinoma at or less than 2 mm from inked specimen margin. The number needed to treat (NNT) to prevent one re-excision was calculated.

Results: We identified 97 women (74 with IBC and 33 with DCIS-only) who had undergone BCS with routine CM sampling during the study period. Mean patient age was 62. Median specimen volume was 178 cc3. 90% of the IBCs were ductal subtype. Mean IBC size was 1.5 cm. 63% of tumors were ER+, 58% PR+, and 7% HER2+. Of the 97 patients in this study, 64 had +LM and 33 had -LM. Of the 64 with +LM, 38 did not have tumor in the CM and 26 had tumor in the CM. Of these 26, 18 had +FM (re-excision needed) and 8 had -FM (no re-excision needed). The proportion of patients with actual tumor at ink (not just close margins) in the lumpectomy specimen was significantly higher among the group with tumor present in the CM than it was in the group with no tumor present in the CM (14/26 versus 7/38, p = 0.006). The NNT with routine CM compared with standard BCS to prevent one re-excision was 2.0 (95% CI, 1.5 — 2.1).

Discussion: In this study the routine use of CM reduced the need for reexcision in women undergoing BCS for IBC or DCIS; one re-excision was avoided for every two patients treated with this surgical approach. The absence of tumor in the CM in the majority of patients with positive LM suggests that specimen radiography and/or pathologic processing techniques may result in artifactually positive LM. Our results indicate that improved specimen imaging and pathological processing techniques are needed to increase the fidelity of margin assessment. In the meantime, the routine use of cavity margins may reduce the need for re-excision in women undergoing BCS.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-14-03.

MRI as an outcome in multiple sclerosis clinical trials

INTRODUCTION

T2-weighted and gadolinium enhanced T1-weighted MRI scans measure plaque burden and breakdown of the blood-brain barrier, respectively, in multiple sclerosis (MS) lesions. These have become widely used outcome measures for monitoring disease activity in clinical trials and clinical practice. However, their use as surrogates or biomarkers for disability and relapses, key clinical outcome measures, has remained incompletely validated.

METHODS

In a clinical trial database comprised of 31 relapsing-remitting and secondary progressive MS trial placebo groups, we assessed relationships between 1) T2 lesion load (TLL) change and disability change and 2) gadolinium enhancement of MS lesions and on-study relapses with univariate and multivariate analyses.

RESULTS

In relapsing-remitting MS, TLL change (n = 223) made no independent contribution to predicting change in disability from baseline to trials' end. Similarly, inclusion of gadolinium enhancing lesions (n = 170) into multivariate models did not independently contribute to the predictive value for on-trial relapses. In secondary progressive MS, a small effect of TLL was found for disability change (n = 355) but in multivariate analysis this accounted for less than 5% of the variance in end-of-trial disability. Results were replicated in independent datasets, more than doubling effective sample sizes.

CONCLUSIONS

MRI measures widely used in trials of relapsing-remitting and progressive multiple sclerosis add little if anything independently to the clinically relevant relapse and disability outcomes. These results reemphasize the importance of validating potential surrogate markers against clinical measures and highlight the need for better MRI markers of disease activity and progression.

Subcutaneous emphysema secondary to foreign-body aspiration

Pneumomediastinum is uncommon in pediatric medical practice, outside the neonatal period. While asthma or respiratory infections are the most frequent underlying causes, it is important not to forget the possibility of foreign body aspiration, particularly after the clinical presentation.

Screening for diabetic retinopathy in rural areas: the potential of telemedicine

Diabetic retinopathy is a common cause of blindness, and screening can identify the disease at an earlier, more treatable stage. However, rural individuals with diabetes may have limited access to needed eye care. The objective of this project was to demonstrate the feasibility of a diabetic retinopathy screening program using a state-of-the-art nonmydriatic digital fundus imaging system. The study involved a series of patients screened in primary care and public health locations throughout seven predominantly rural counties in eastern North Carolina. Images of each fundus were obtained and sent to a retinal specialist. The retinal specialist reviewed each image, recorded image quality, diagnosed eye disease and made recommendations for subsequent care. Of 193 volunteers with a history of diabetes mellitus, 96.3 percent reported that they were very comfortable or comfortable with the camera. Eighty-five percent of images were rated as good or fair by the retinal specialist. The retinal specialist also reported being very certain or certain of the diagnosis in 84 percent of cases. Image quality correlated highly with the certainty of diagnosis (Spearman's rank order correlation coefficient = 0.79; P < 0.001). The average time since the previous examination by an eye care specialist for diabetic subjects was two years. Approximately 62 percent of diabetic patients had diagnosable eye conditions, the most common of which was diabetic retinopathy (40.9 percent). In this convenience sample, African Americans, despite similar age and disease duration, were more likely to have retinopathy. Digital imaging is a feasible screening modality in rural areas, may improve access to eye care, and may improve compliance with care guidelines for individuals with diabetes mellitus.

Resources and characteristics of elderly women who live alone

This article is a report of findings from a longitudinal descriptive study of 15 women age 76 to 92 who were living alone in the community. Data collection began in 1983. Two survivors were still living alone in 1997. The naturalistic inquiry paradigm guided data collection and analysis (Guba & Lincoln, 1989). Data were collected during repeated audio-taped "conversations" with each woman. Individual "chunks" of data were labeled, sorted, and organized into categories. The 15 categories that evolved from the data were then grouped as resources and characteristics. The prevailing theme was "independence." A woman's value system was a mediator that influenced her ability to continue living alone.

Fast T2-mapping with snapshot flash imaging

It has been shown recently that quantitative T2-maps may be measured by acquisition of a series of at least eight T2-weighted SNAPSHOT FLASH images. These measurements require a relaxation delay of 10-15 s after each T2-weighted image for the complete relaxation of the spin system. This results in long measuring times. The method presented in this paper allows a considerable reduction of the measuring time by combining the T2-sequence with a fast T1-measurement. Quantitative T1- and T2-maps may be acquired simultaneously in less than 30 s. The method was tested in a phantom experiment. In an in vivo application, relaxation times of different tissues in the abdomen of a rat were measured.

The influence of HLA-DR and -DQ alleles on progression to multiple sclerosis following a clinically isolated syndrome

A 5-year follow-up study was performed on 70 Caucasian patients presenting with isolated neurological syndromes of the optic nerve, brain stem, or spinal cord to assess the risk of progression to MS. The influence on patient prognosis of HLA-DR and -DQ alleles and presentation with disseminated brain lesions, demonstrated by MRI scanning, was determined. Clinical progression to MS was observed in 61% of optic neuritis patients, 50% of patients with a brain-stem syndrome, and 35% of patients with a spinal cord disturbance. MS and the isolated clinical syndromes were positively associated with DRB1*1501, DQA1*0102, and DQB1*0602; the frequency of these alleles in the latter group was intermediate between that seen in MS patients and healthy controls. Conversion to MS was positively associated with the DRB1*1501.DQA1*0102.DQB1*0602 haplotype, but the influence of HLA was only significant in patients with disseminated brain lesions at presentation (MRI positive); MS developed in 86% of MRI-positive, DRB1*1501-positive patients compared with 55% of MRI-positive, DRB1*1501-negative patients (p < 0.025). The data suggest that these HLA alleles are involved in susceptibility to initial demyelinating lesion formation and are important in the subsequent development of MS in MRI-positive patients.

Blood transfusion and laryngeal cancer

Evidence exists to suggest a detrimental effect of blood transfusion on survival after resection for malignant disease. Immune suppression due to transfusion has been implicated, though this remains unproven. We have conducted a retrospective study of 69 patients (38 transfused, 31 not transfused) with squamous carcinoma of the larynx to assess the effect of blood transfusion on survival after laryngectomy. Patients were compared for age, sex, smoking habit, tumour site and stage, grade of operating surgeon, preoperative haemoglobin, tumour nucleolar organizer region status, and operation time. The minimum follow-up was 5 years. In the transfused group 21/38 died as a result of their malignant disease and only 4/31 in the untransfused group. This difference was highly significant (P less than 0.001, chi-squared test) and using a multivariate analysis the only variable associated with a decreased survival time was whether a blood transfusion had been received. We conclude that peri-operative blood transfusion is associated with decreased survival after laryngectomy. However, whether this association is causal remains unproven.

Spontaneous insertion of an IS2 element into the promoter region of the lac operon

A spontaneous mutation in pUC18 has revealed the insertion of a chromosomal insertion sequence (IS)2 element into the promoter region of the lac operon. The IS2 insertion site, at the pentanucleotide sequence TCGAG, is unlike previously described junctional sequences.

Plasmids in bacteria exposed to activated neutrophils mediate mutagenesis when transferred to new hosts

The plasmid pUC18 contains a lacZ alpha-complementation gene that codes for a small peptide that can complement the delta M15 mutation of the Escherichia coli lacZ (beta-galactosidase) gene, converting bacteria carrying that mutated gene from the lacZ- to the lacZ+ phenotype. This plasmid was used in experiments designed to study mutagenesis by human neutrophils. E coli carrying pUC18 were incubated with neutrophils under conditions in which little ingestion of the bacteria took place; the plasmid was then isolated and transformed into an E coli strain (BOZO) that carries the lacZ delta M15 mutation. Of these transformants, 11 of 205,000 were lacZ, suggesting that in these 11, alpha-complementation had been lost through a mutation. No lac- colonies were detected among several hundred thousand BOZO transformed with plasmid isolated from incubations in which phagocytosis could take place, nor from incubations from which neutrophils were omitted. Despite the lac- phenotype of these 11 transformants, plasmids reisolated from nine of them showed normal alpha-complementing ability when transformed into fresh BOZO. These findings indicated that in these nine, the mutations were located in the chromosomes of the transformed BOZO. It thus appears that on exposure to activated neutrophils, a plasmid may acquire a lesion (? mutation) that can somehow be transferred to the genome of a recipient microorganism, resulting in repair of the damaged plasmid accompanied by mutation of the recipient's chromosome. Restriction mapping of the DNA from four of these nine chromosomal mutants suggested that the mutations did not represent major insertions or deletions in the portion of the bacterial chromosome corresponding to the pUC18 lac operon insert, nor in the remainder of the lacZ delta M15 gene. These results confirm previous work showing that exposure to activated neutrophils can induce mutations in biological systems, and provides an experimental model in which the mechanism of neutrophil-mediated mutagenesis may be examined.

Does the purity of intraportal islet isografts affect their endocrine function?

The effect of collagenase digested pancreatic tissue upon the endocrine function of intraportal islet isografts has been studied in rats. The ability of transplanted islets to restore normoglycemia in recipients was not affected by tissue contamination, but the insulin response to glucose challenge 12 weeks after transplantation was negatively correlated with the amylase content of this additional tissue transplant. All animals receiving a single dispersed pancreas died within 24 hr. These findings are discussed in relation to transplantation of the dispersed pancreas in human.

A new tetracycline-resistance determinant, class E, isolated from Enterobacteriaceae

A fifth tetracycline(Tc)-resistance determinant, designated class E, has been identified on a transferable plasmid found in a fecal strain of Escherichia coli. This determinant does not show homology by DNA-DNA hybridization at high stringency with any of four other Tc resistance determinants (classes A, B, C and D) previously described among the Enterobacteriaceae. Resistance is inducible by 1 microgram Tc/ml and increases the minimum inhibitory concentration 130-fold for Tc and 3.5-fold for minocycline. The mechanism, like that of the other four determinants examined, appears to involve an active efflux of the drug. Using a 32P-labeled cloned fragment containing the resistance determinant, we have found the determinant in Aeromonas, but not in any of over 200 other E. coli strains tested.

Bladder and ureteral pressure relationships in nonhuman primates

Bladder pressures during filling are precisely paralleled by ureteral resistance to perfusion. The pressure relationships are identical in normal, spinal and decentralized nonhuman primates, none of which had vesicoureteral reflux. Intravesical and thus intraureteral pressures are higher in animals with neurological lesions, particularly decentralization.

In vivo potentiation of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea by the radiation sensitizer benznidazole

Recent studies in mouse tumor systems have indicated a potential therapeutic advantage in combining the radiosensitizer misonidazole (MISO) with cancer chemotherapy drugs. One agent the antitumor activity of which has been enhanced to a greater extent than its hematological or gastrointestinal toxicities is the nitrosourea, 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU). Recently, sensitizers more lipophylic than MISO have been reported to give greater tumor response enhancement when combined with CCNU. The present studies compared the potential therapeutic benefit of combining MISO (partition coefficient, 0.43) or benznidazole (BENZO) (partition coefficient, 8.5) in KHT sarcoma or RIF-1 tumor-bearing C3H mice. Both sensitizers were administered i.p. and given either 30 min before (BENZO) or simultaneously with (MISO) the chemotherapeutic agent. Survival of clonogenic tumor cells assessed 22 to 24 hr after treatment or in situ tumor growth delay were used as assays of tumor response. Normal tissue toxicity was determined using the drug dose yielding 50% animal lethality in 30 days end point. When combined with CCNU, doses of MISO (5.0 mmol/kg) or BENZO (0.3 mmol/kg) were found to yield approximately equivalent increases in both the tumor effect (enhancement ratio, approximately 1.8 to 2.0) and normal tissue toxicity (enhancement ratio approximately 1.3 to 1.4). Both sensitizers therefore led to a therapeutic benefit. However, although a approximately 10-fold lower dose of the more lipophylic sensitizer BENZO proved to be as effective as MISO at enhancing the tumoricidal effects of CCNU, this dose reduction did not result in a greater therapeutic gain for BENZO.