Faculty Entrustment and Resident Entrustability

Importance

As the surgical education paradigm transitions to entrustable professional activities, a better understanding of the factors associated with resident entrustability are needed. Previous work has demonstrated intraoperative faculty entrustment to be associated with resident entrustability. However, larger studies are needed to understand if this association is present across various surgical training programs.

Objective

To assess intraoperative faculty-resident behaviors and determine if faculty entrustment is associated with resident entrustability across 4 university-based surgical training programs.

Design, Setting, and Participants

This cross-sectional study was conducted at 4 university-based surgical training programs from October 2018 to May 2022. OpTrust, a validated tool designed to assess both intraoperative faculty entrustment and resident entrustability behaviors independently, was used to assess faculty-resident interactions. A total of 94 faculty and 129 residents were observed. Purposeful sampling was used to create variation in type of operation performed, case difficulty, faculty-resident pairings, faculty experience, and resident training level.

Main Outcomes and Measures

Observed resident entrustability scores (scale 1-4, with 4 indicating full entrustability) were compared with reported measures (faculty level, case difficulty, resident postgraduate year [PGY], resident gender, observation month) and observed faculty entrustment scores (scale 1-4, with 4 indicating full entrustment). Path analysis was used to explore direct and indirect effects of the predictors. Associations between resident entrustability and faculty entrustment scores were assessed by pairwise Pearson correlation coefficients.

Results

A total of 338 cases were observed. Cases observed were evenly distributed by faculty experience (1-5 years' experience: 67 [20.9%]; 6-14 years' experience: 186 [58%]; ≥15 years' experience: 67 [20.9%]), resident PGY (PGY 1: 28 [8%]; PGY 2: 74 [22%]; PGY 3: 64 [19%]; PGY 4: 40 [12%]; PGY 5: 97 [29%]; ≥PGY 6: 36 [11%]), and resident gender (female: 183 [54%]; male: 154 [46%]). At the univariate level, PGY (mean [SD] resident entrustability score range, 1.44 [0.46] for PGY 1 to 3.24 [0.65] for PGY 6; F = 38.92; P < .001) and faculty entrustment (2.55 [0.86]; R2 = 0.94; P < .001) were significantly associated with resident entrustablity. Path analysis demonstrated that faculty entrustment was associated with resident entrustability and that the association of PGY with resident entrustability was mediated by faculty entrustment at all 4 institutions.

Conclusions and Relevance

Faculty entrustment remained associated with resident entrustability across various surgical training programs. These findings suggest that efforts to develop faculty entrustment behaviors may enhance intraoperative teaching and resident progression by promoting resident entrustability.

Patient factors related to patient engagement technology (PET) usage in thoracic surgery

BACKGROUND

We evaluated using Patient Engagement Technology (PET) to capture Patient Reported Outcomes (PROs) in thoracic surgery patients. METHODSY: atients using a PET received surveys including the Patient-Reported Outcomes Measurement Information System Global-10 (PROMIS-10) and a health literacy (HL) screen. The relationship of patient-level factors with survey completion was assessed through univariate and logistic regression analyses.

RESULTS

703 patients enrolled in a PET. 52 ​% were female and 83 ​% were white with a median age of 63.72 ​% had adequate HL. 81 ​% completed the PROMIS-10 survey. Univariate analysis found lower rates of PROMIS-10 completion in male patients and those with inadequate HL. Logistic regression analysis showed adequate HL (OR 1.76) and white race (OR 1.72) were associated with PROMIS-10 survey completion, while male gender (OR 0.65) had the opposite effect.

CONCLUSIONS

PETs are an effective means of collecting PROs, but use is affected by gender, race, and health literacy.

Correlation between Multiparametric MR Imaging and Molecular Genetics in Pontine Pediatric High-Grade Glioma

BACKGROUND AND PURPOSE

Molecular profiling is a crucial feature in the "integrated diagnosis" of CNS tumors. We aimed to determine whether radiomics could distinguish molecular types of pontine pediatric high-grade gliomas that have similar/overlapping phenotypes on conventional anatomic MR images.

MATERIALS AND METHODS

Baseline MR images from children with pontine pediatric high-grade gliomas were analyzed. Retrospective imaging studies included standard precontrast and postcontrast sequences and DTI. Imaging analyses included median, mean, mode, skewness, and kurtosis of the ADC histogram of the tumor volume based on T2 FLAIR and enhancement at baseline. Histone H3 mutations were identified through immunohistochemistry and/or Sanger or next-generation DNA sequencing. The log-rank test identified imaging factors prognostic of survival from the time of diagnosis. Wilcoxon rank-sum and Fisher exact tests compared imaging predictors among groups.

RESULTS

Eighty-three patients had pretreatment MR imaging and evaluable tissue sampling. The median age was 6 years (range, 0.7-17 years); 50 tumors had a K27M mutation in H3-3A, and 11, in H3C2/3. Seven tumors had histone H3 K27 alteration, but the specific gene was unknown. Fifteen were H3 wild-type. Overall survival was significantly higher in H3C2/3- compared with H3-3A-mutant tumors (P = .003) and in wild-type tumors compared with any histone mutation (P = .001). Lower overall survival was observed in patients with enhancing tumors (P = .02) compared with those without enhancement. H3C2/3-mutant tumors showed higher mean, median, and mode ADC_total values (P < .001) and ADC_enhancement (P < .004), with lower ADC_total skewness and kurtosis (P < .003) relative to H3-3A-mutant tumors.

CONCLUSIONS

ADC histogram parameters are correlated with histone H3 mutation status in pontine pediatric high-grade glioma.

Psychosocial Determinants of Readmission After Surgery

BACKGROUND

Quality of life and psychosocial determinants of health, such as health literacy and social support, are associated with increased health care utilization and adverse outcomes in medical populations. However, the effect on surgical health care utilization is less understood.

OBJECTIVE

We sought to examine the effect of patient-reported quality of life and psychosocial determinants of health on unplanned hospital readmissions in a surgical population.

RESEARCH DESIGN

This is a prospective cohort study using patient interviews at the time of hospital discharge from a Veterans Affairs hospital.

SUBJECTS

We include Veterans undergoing elective inpatient general, vascular, or thoracic surgery (August 1, 2015-June 30, 2017).

MEASURES

We assessed unplanned readmission to any medical facility within 30 days of hospital discharge.

RESULTS

A total of 736 patients completed the 30-day postoperative follow-up, and 16.3% experienced readmission. Lower patient-reported physical and mental health, inadequate health literacy, and discharge home with help after surgery or to a skilled nursing or rehabilitation facility were associated with an increased incidence of readmission. Classification regression identified the patient-reported Veterans Short Form 12 (SF12) Mental Component Score <31 as the most important psychosocial determinant of readmission after surgery.

CONCLUSIONS

Mental health concerns, inadequate health literacy, and lower social support after hospital discharge are significant predictors of increased unplanned readmissions after major general, vascular, or thoracic surgery. These elements should be incorporated into routinely collected electronic health record data. Also, discharge plans should accommodate varying levels of health literacy and consider how the patient's mental health and social support needs will affect recovery.

Health Literacy in Surgery

Background:

Low health literacy is associated with poor health outcomes in many chronic diseases and may have an important role in determining surgical outcomes. This study aims to comprehensively review the current state of science on adult health literacy in surgery and to identify knowledge gaps for future research.

Methods:

Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic search was conducted to identify all studies from January 2002 through May 2018 that used validated instruments to assess health literacy among adult patients undergoing surgery. Studies were assessed for quality using the Newcastle-Ottawa scale and evaluated on findings by their focus on identifying health literacy levels, understanding associations with surgical outcomes, and/or developing interventions to address low health literacy.

Key Results:

There were 51 studies on health literacy with data from 22,139 patients included in this review. Low health literacy was present in more than one-third of surgical patients (34%, interquartile range 16%–50%). The most commonly used validated instrument for assessment of health literacy in the surgical population was the Newest Vital Sign. Most studies were focused on identifying the prevalence of low health literacy within a surgery population (84%, n = 43). Few studies focused on understanding the association of health literacy to surgical outcomes (12%, n = 6) and even fewer studies developed interventions to address health literacy (4%, n = 2).

Discussion:

Low health literacy is common among surgical patients. Important opportunities exist to better understand the role of health literacy in determining surgical outcomes and to develop more health literacy-sensitive models of surgical care. [HLRP: Health Literacy Research and Practice. 2020;4(1):e45–e65.]

Plain Language Summary:

Health literacy has not been well-studied in surgery but likely plays an important role. In this article, we reviewed all current research on health literacy in surgery to help us understand where we are at and where we need to go. We found that low health literacy is common and we need more ways to address it in surgery.

Emotional Intelligence and Burnout in Surgical Residents: A 5-Year Study

OBJECTIVE

We sought to characterize the interactions of burnout with internal and external factors over the past 5 years for surgery residents at our institution. We hypothesized that burnout levels would be consistent among years, inversely related to emotional intelligence (EI) and job resources, and directly related to disruptive behaviors.

DESIGN

General surgery residents at a single institution were invited to complete a survey each year from 2015 to 2019 that included a combination of the 22-item Maslach-Burnout Inventory, 30-item trait EI questionnaire, as well as focused questions assessing disruptive behaviors (8 items), job resources (8 items), and demographic characteristics. Burnout was defined as scoring high in depersonalization (≥ 10 points) or emotional exhaustion (≥ 27 points). Student's t tests and Wilcoxon tests were used to compare continuous variables; chi-square and Fisher's exact tests were used to compare categorical variables, as appropriate. Spearman's rho was used to calculate correlation. A logistic regression and separate linear regression model were constructed to assess relation of variables to burnout.

SETTING

The general surgery residency program at the University of Alabama at Birmingham, Birmingham, Alabama, a large tertiary care academic center.

RESULTS

An average of 47 surveys were completed each year, for a total of 236 (response rate 81%). One hundred seventeen (58.5%) met criteria for burnout. Burnout rates each year ranged from 68% to 53%, with the lowest value occurring in 2019. Incidence of burnout was lowest among the postgraduate year (PGY) 1 class and highest among the PGY5 class (38% versus 64%, p = 0.02). Individuals without burnout had higher scores for EI overall (5.7 versus 5.3, p < 0.001) as well as in each of its 4 subcomponents (p < 0.001). Individuals who were subjected to disruptive behaviors, particularly others taking credit for work and public humiliation, were more likely to experience burnout (p = 0.02). Those with burnout also had significantly lower scores in each of the 4 domains of the Job Resources model (p < 0.01). On multivariate logistic regression, increasing PGY level remained a significant predictor of burnout risk. Each of the sub-domains of EI and jobs resources inversely corelated with burnout, while disruptive behaviors directly correlated with burnout. ON subsequent multivariable linear regression, resident well-being and professional development remained independent predictors of lower burnout scores.

CONCLUSIONS

Burnout is prevalent among trainees at our institution, but a trend toward improvement has been shown over 5 years. Burnout rates increase each year of surgical training beyond PGY2. Factors that mitigate burnout include resident well-being and professional development. Disruptive behaviors lead to increase burnout rates.

Do Internal or External Characteristics More Reliably Predict Burnout in Resident Physicians: A Multi-institutional Study

INTRODUCTION

Surgical residents have been shown to experience high rates of burnout. Whether this is influenced predominately by intrinsic characteristics, external factors, or is multifactorial has not been well studied. The aim of this study was to explore the relationship between these elements and burnout. We hypothesized that residents with higher emotional intelligence scores, greater resilience and mindfulness, and better work environments would experience lower rates of burnout.

METHODS

General surgery residents at 7 sites in the US were invited to complete an electronic survey in 2019 that included the 2-item Maslach Burnout Inventory, Brief Emotional Intelligence Scale, Revised Cognitive and Affective Mindfulness Scale, 2-Item Connor-Davidson Resilience Scale, Utrecht Work Engagement Scale, and Job Resources scale of the Job Demands-Resources Questionnaire. Individual constructs were assessed for association with burnout, using multivariable logistic regression models. Residents' scores were evaluated in aggregate, in groups according to demographic characteristics, and by site.

RESULTS

Of 284 residents, 164 completed the survey (response rate 58%). A total of 71% of respondents were at high risk for burnout, with sites ranging from 57% to 85% (p = 0.49). Burnout rates demonstrated no significant difference across gender, PGY level, and respondent age. On bivariate model, no demographic variables were found to be associated with burnout, but the internal characteristics of emotional intelligence, resilience and mindfulness, and the external characteristics of work engagement and job resources were each found to be protective against burnout (p < 0.001 for all). However, multivariable models examining internal and external characteristics found that no internal characteristics were associated with burnout, while job resources (coeff. -1.0, p-value <0.001) and work engagement (coeff. -0.76, p-value 0.032) were significantly protective factors. Rates of engagement overall were high, particularly with respect to work "dedication."

CONCLUSIONS

A majority of residents at multiple institutions were at high risk for burnout during the study period. Improved work engagement and job resources were found to be more strongly associated with decreased burnout rates when compared to internal characteristics. Although surgical residents appear to already be highly engaged in their work, programs should continue to explore ways to increase job resources, and further research should be aimed at elucidating the mediating effect of internal characteristics on these external factors.

Low Health Literacy Exists in the Inflammatory Bowel Disease (IBD) Population and Is Disproportionately Prevalent in Older African Americans

BACKGROUND

Low health literacy is common in general populations, but its prevalence in the inflammatory bowel disease (IBD) population is unclear. The objective of this study was to assess the prevalence of low health literacy in a diverse IBD population and to identify risk factors for low health literacy.

METHODS

Adult patients with IBD at a single institution from November 2017 to May 2018 were assessed for health literacy using the Newest Vital Sign (NVS). Demographic and socioeconomic data were also collected. Primary outcome was the prevalence of low health literacy. Secondary outcomes were length-of-stay (LOS) and 30-day readmissions after surgical encounters. Bivariate comparisons and multivariable regression were used for analyses.

RESULTS

Of 175 IBD patients, 59% were women, 23% were African Americans, 91% had Crohn disease, and mean age was 46 years (SD = 16.7). The overall prevalence of low health literacy was 24%. Compared to white IBD patients, African Americans had significantly higher prevalence of low health literacy (47.5% vs 17.0%, P < 0.05). On multivariable analysis, low health literacy was associated with older age and African American race (P < 0.05). Of 83 IBD patients undergoing abdominal surgery, mean postoperative LOS was 5.5 days and readmission rate was 28.9%. There was no significant difference between LOS and readmissions rates by health literacy levels.

CONCLUSIONS

Low health literacy is present in IBD populations and more common among older African Americans. Opportunities exist for providing more health literacy-sensitive care in IBD to address disparities and to benefit those with low health literacy.

Biochemical Predictors of Response to Neoadjuvant Therapy in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is becoming increasingly more common. Treatment for PDAC is dependent not only on stage at diagnosis, but complex anatomical relationships. Recently, the therapeutic approach to this disease has shifted from upfront surgery for technically resectable lesions to a neoadjuvant therapy first approach. Selecting an appropriate regimen and determining treatment response is crucial for optimal oncologic outcome, especially since radiographic imaging has proven unreliable in this setting. Tumor biomarkers have the potential to play a key role in treatment planning, treatment monitoring, and surveillance as an adjunct laboratory test. In this review, we will discuss common chemotherapeutic options, mechanisms of resistance, and potential biomarkers for PDAC. The aim of this paper is to present currently available biomarkers for PDAC and to discuss how these markers may be affected by neoadjuvant chemotherapy treatment. Understanding current chemotherapy regiments and mechanism of resistance can help us understand which markers may be most affected and why; therefore, determining to what ability we can use them as a marker for treatment progression, prognosis, or potential relapse.

Physical, Laboratory, Radiographic, and Endoscopic Workup for Clostridium difficile Colitis

Clostridium (reclassified as " Clostridioides ") difficile colitis is a common nosocomial infection associated with increased morbidity and mortality. Like many clinical encounters, a focused history and physical examination will help to guide initial management. Further laboratory testing will assist with diagnosis through stool studies, and blood tests, such as white blood cell counts and serum creatinine, can help to stratify patients into illness severity groups for treatment decisions. Radiographic evaluation can be helpful in patients with severe disease and concern for complicated colitis. Endoscopic evaluation should be carefully considered in patients with suspected mucosal injury secondary to infections and plays a role when an alternative diagnosis is suspected. Treatment options depend on the clinical presentation and can range from antibiotic therapy to emergent surgery to fecal transplantation for recurrent episodes. Care for these patients is often challenging, but through a systemic workup the appropriate treatment may be delivered.

Invited Review: Emerging functions of histone H3 mutations in paediatric diffuse high-grade gliomas

Paediatric diffuse high-grade gliomas (pHGG) are rare, but deadly tumours. The discovery of recurrent mutations in the tail of histone H3, changing lysine 27 to methionine, or glycine 34 to arginine or valine, has illuminated a critical role for epigenetic dysregulation in the aetiology of childhood gliomas and opened new avenues of exploration that have resulted in numerous advances for the field. In this review, we describe the current models of H3K27M mutant cancer that are available to the research community and the insights they have provided on tumour biology and the epigenetic and transcriptional effects of histone mutations. We also review the current understanding of the H3G34R/V mutation and the therapeutic outlook for the treatment of pHGG.

Preoperative opioid use and postoperative pain associated with surgical readmissions

BACKGROUND

The extent of preoperative opioid utilization and the relationship with pain-related readmissions are not well understood.

METHODS

VA Surgical Quality Improvement Program data on general, vascular, and orthopedic surgeries (2007-2014) were merged with pharmacy data to evaluate preoperative opioid use and pain-related readmissions. Opioid use in the 6-month preoperative period was categorized as none, infrequent, frequent, and daily.

RESULTS

In the six-month preoperative period, 65.7% had no opioid use, 16.7% had infrequent use, 6.3% frequent use, and 11.4% were daily opioid users. Adjusted odds of pain-related readmission were higher for opioid-exposed groups vs the opioid-naïve group: infrequent (OR 1.17; 95% CI:1.04-1.31), frequent (OR 1.28; 95% CI:1.08-1.52), and daily (OR 1.49; 95% CI:1.27-1.74). Among preoperative opioid users, those with a pain-related readmission had higher daily preoperative oral morphine equivalents (mean 44.5 vs. 36.1, p < 0.001).

CONCLUSIONS

Patients using opioids preoperatively experienced higher rates of pain-related readmissions, which increased with frequency and dosage of opioid exposure.

Review: insights gained from modelling high-grade glioma in the mouse

High-grade gliomas (HGGs) are devastating primary brain tumours with poor outcomes. Advances towards effective treatments require improved understanding of pathogenesis and relevant model systems for preclinical testing. Mouse models for HGG provide physiologically relevant experimental systems for analysis of HGG pathogenesis. There are advantages and disadvantages to the different methodologies used to generate such models, including implantation, genetic engineering or somatic gene transfer approaches. This review highlights how mouse models have provided insights into the contribution of specific mutations to tumour initiation, progression and phenotype, the influence of tumour micro-environment, and the analysis of cell types that can give rise to glioma. HGGs are a heterogeneous group of tumours, and the complexity of diverse mutations within common signalling pathways as well as the developmental and cell-type context of transformation contributes to the overall diversity of glioma phenotype. Enhanced understanding of the mutations and cell types giving rise to HGG, along with the ability to design increasingly complex mouse models that more closely simulate the process of human gliomagenesis will continue to provide improved experimental systems for dissecting mechanisms of disease pathogenesis and for preclinical testing.

Pressure pain tolerance at different sites on the quadriceps femoris prior to and following eccentric exercise

Downhill running, particularly for the untrained subject, is a mode of eccentric exercise that produces delayed-onset muscle soreness (DOMS) in the quadriceps femoris muscle which is maximal between 24 and 72 h after the exercise. It is not clear whether sensitivity to pain is uniform over the surface of the muscle, or whether some locations become more sensitive following eccentric exercise. The purpose of this investigation was to compare pressure pain tolerance (PPTO) at various sites on the quadriceps femoris muscle on 2 days prior to exercise, immediately after, and at 24, 48 and 72 h following a bout of eccentric exercise. Fifteen untrained female subjects performed a 40 min downhill run on a motorized treadmill with a gradient of -12%, where running speed was adjusted to elicit a heart rate of approximately 60% of age-related maximum heart rate reserve, and were measured for PPTO at seven sites on the right thigh. Sites were visited sequentially three times and repeated on each of 6 days. Pressure pain tolerance as an index of tenderness was determined using a strain gauge algometer. Two sites were close to the distal myotendinous junction, three sites were located on the mid belly of the muscle and two sites were located at the proximal myotendinous junction. There was a significant difference (p<0.01) in PPTO between muscle sites prior to eccentric exercise (Days 1 and 2), and a significant difference between sites following eccentric exercise (p<0.01). Sites close to the distal and proximal myotendinous junction were most sensitive to pain (p<0.01). There was no difference in PPTO at any site across the belly of the muscle. These results suggest that the belly of the quadriceps femoris is the most suitable area for measurement of PPTO.

Control and eradication of invasive mammals in Great Britain

This paper provides a 'long view' of the eradication and control of invasive mammals by reviewing the management of 24 mammalian species that have been introduced into Great Britain since the Neolithic period and have subsequently established free-living populations in the wild. The approach provides examples of the issues faced when managing populations and examines some of the lessons that can be learned from successes and failures. The species are covered in the order of introduction, with the control/eradication of rabbit (Oryctolagus cuniculus), muskrat (Ondatra zibethicus), coypu (Myocastor coypus) and American mink (Mustela vison) considered in more detail. The species accounts are set within the context of commitments for the control of invasive alien species made by parties to the Convention on Biological Diversity and guidance provided by the International Union for Conservation of Nature and the Council of Europe. These have led to improvements in the process for assessing risks and co-ordinating action. However, despite some notable cases documented here, there have been few successful eradication programmes carried out in Europe. This paper argues that there is a case for building on the improved frameworks that are being developed in the United Kingdom and elsewhere and for being more ambitious with goals for the management of invasive alien species.

Prolactin regulation of testosterone secretion and testes growth in DLS rams at the onset of seasonal testicular recrudescence

Our objective was to test the hypothesis that prolactin (PRL) acts at both the pituitary and testis levels to regulate testosterone secretion in the adult ram. The focus was on the mid-regression to mid-redevelopment stages of a photoperiod-condensed ‘seasonal’ testicular cycle. DLS rams (six per group) were given daily s.c. injections of bromocriptine (4 mg) or vehicle during the entire period. Serum PRL concentration in control rams peaked at 103.4±22.1 ng/ml in late regression and then steadily declined (P<0.01) to 19.5±4.3 ng/ml, whereas PRL in treated rams was always ≤4.0 ng/ml. Suppression of PRL tended (P<0.10) to increase the amplitude of natural LH pulses (transition stages) or reduce the number of LH receptors in the testis (regressed stage), although neither change disturbed testosterone levels in peripheral blood. These subtle changes were accompanied by significant (P<0.05) alterations in the capability of the pituitary to release LH (85% more) and of the testes to secrete testosterone (20% less). These effects of PRL were unmasked when rams were given highly stimulative i.v. injections of GNRH (single 3 μg dose) and NIH-oLH-S24 (three 5 μg doses given 20 min apart) respectively. PRL insufficiency also appeared to slow down the ‘seasonal’ rise in FSH secretion and slightly delayed (2 weeks) the times when the testes began to grow and were first significantly (P<0.05) enlarged from the regressed state. We conclude that PRL is an important part of the intricate regulation of the pituitary–gonadal system in moderately seasonal DLS rams.

Blockade of mGluR1 receptor results in analgesia and disruption of motor and cognitive performances: effects of A-841720, a novel non-competitive mGluR1 receptor antagonist

BACKGROUND AND PURPOSE

To further assess the clinical potential of the blockade of metabotropic glutamate receptors (mGluR1) for the treatment of pain.

EXPERIMENTAL APPROACH

We characterized the effects of A-841720, a novel, potent and non-competitive mGluR1 antagonist in models of pain and of motor and cognitive function.

KEY RESULTS

At recombinant human and native rat mGluR1 receptors, A-841720 inhibited agonist-induced calcium mobilization, with IC50 values of 10.7+/-3.9 and 1.0 +/- 0.2 nM, respectively, while showing selectivity over other mGluR receptors, in addition to other neurotransmitter receptors, ion channels, and transporters. Intraperitoneal injection of A-841720 potently reduced complete Freund's adjuvant-induced inflammatory pain (ED50 = 23 micromol kg(-1)) and monoiodoacetate-induced joint pain (ED50 = 43 micromol kg(-1)). A-841720 also decreased mechanical allodynia observed in both the sciatic nerve chronic constriction injury and L5-L6 spinal nerve ligation (SNL) models of neuropathic pain (ED50 = 28 and 27 micromol kg(-1), respectively). Electrophysiological studies demonstrated that systemic administration of A-841720 in SNL animals significantly reduced evoked firing in spinal wide dynamic range neurons. Significant motor side effects were observed at analgesic doses and A-841720 also impaired cognitive function in the Y-maze and the Water Maze tests.

CONCLUSIONS AND IMPLICATIONS

The analgesic effects of a selective mGluR1 receptor antagonist are associated with motor and cognitive side effects. The lack of separation between efficacy and side effects in pre-clinical models indicates that mGluR1 antagonism may not provide an adequate therapeutic window for the development of such antagonists as novel analgesic agents in humans.

Mosaic trisomy 6 and maternal uniparental disomy 6 in a 23-week gestation fetus with atrioventricular septal defect

Trisomy 6 is seen in early miscarriages in association with an intact, empty amniotic sac or as a pseudomosaic in amniotic fluid cultures. We report the finding of mosaic trisomy 6 in a 23-week-gestation pregnancy terminated because of intrauterine death. The post-mortem showed a well formed macerated male fetus with an atrioventricular septal defect and an exomphalos. By conventional cytogenetics, trisomy 6 was found in 12 out of 25 (48%) fibroblast colonies from fetal skin and 21 out of 32 (66%) colonies derived from amnion, while the remaining metaphases showed an apparently normal male karyotype. Molecular genetic studies on DNA from uncultured fetal skin and cord samples using polymorphic microsatellite repeat sequences showed no evidence of trisomy 6, but demonstrated that both chromosome 6 homologs were of maternal origin consistent with maternal uniparental disomy (UPD).

Role of FSH, numbers of FSH receptors and testosterone in the regulation of inhibin secretion during the seasonal testicular cycle of adult rams

The regulation of inhibin secretion has not been elucidated fully in male ruminants. The aim of this study was to determine the relative importance of FSH and testosterone concentrations, and FSH receptors, in the control of secretion of immunoactive inhibin in rams. In Expt 1, temporal changes in hormone concentrations and testicular FSH binding were determined for two groups of rams (n = 4) kept under opposite, alternating 4 month periods of long (16 h light:8 h dark) and short (8 h light:16 h dark) days. Testicular biopsies (1-2 g) were collected when the testes were regressed, redeveloping, redeveloped and regressing. In Expt 2, separate groups of rams (n = 4) kept under natural photoperiod (latitude 45 degrees 48 minutes N) were designated as controls or passively immunized (for 3 weeks) with sufficient oestradiol antiserum to increase testosterone secretion without altering LH and FSH; this was done when the testes were regressed (non-breeding season) and redeveloped (breeding season). In both groups of rams (Expt 1), 'seasonal' increases in FSH concentrations began a few weeks earlier than did increases in inhibin concentrations. FSH reached maximum concentrations during testicular recrudescence, whereas numbers of FSH receptors in the testis and circulatory inhibin concentrations did not reach peak values until the testes were fully developed. Numbers of FSH receptors per testis, but not FSH concentration, were positively correlated (r = 0.65) with inhibin concentrations across the four stages of the testicular cycle. Near the end of testicular recrudescence early in the breeding season (Expt 2), relatively high FSH concentration was associated with increased abundance of FSH receptor mRNA (90%) and number of receptors (45%) in the testis and increased inhibin concentrations (50%), compared with when the testes were regressed. Moderate, physiological increases in testosterone secretion in immunized rams did not affect inhibin in either season. These results indicate that: (i) FSH stimulation of immunoactive inhibin secretion by Sertoli cells as testes recrudesce is via increases in secretion (early) and cognate receptors (late); (ii) FSH upregulates the synthesis of its own receptor late in recrudescence; and (iii) the positive correlation (r = 0.70) observed between circulatory testosterone and immunoactive inhibin does not reflect a causal relationship.

Role of FSH, numbers of FSH receptors and testosterone in the regulation of inhibin secretion during the seasonal testicular cycle of adult rams

The regulation of inhibin secretion has not been elucidated fully in male ruminants. The aim of this study was to determine the relative importance of FSH and testosterone concentrations, and FSH receptors, in the control of secretion of immunoactive inhibin in rams. In Expt 1, temporal changes in hormone concentrations and testicular FSH binding were determined for two groups of rams (n = 4) kept under opposite, alternating 4 month periods of long (16 h light:8 h dark) and short (8 h light:16 h dark) days. Testicular biopsies (1-2 g) were collected when the testes were regressed, redeveloping, redeveloped and regressing. In Expt 2, separate groups of rams (n = 4) kept under natural photoperiod (latitude 45 degrees 48 minutes N) were designated as controls or passively immunized (for 3 weeks) with sufficient oestradiol antiserum to increase testosterone secretion without altering LH and FSH; this was done when the testes were regressed (non-breeding season) and redeveloped (breeding season). In both groups of rams (Expt 1), 'seasonal' increases in FSH concentrations began a few weeks earlier than did increases in inhibin concentrations. FSH reached maximum concentrations during testicular recrudescence, whereas numbers of FSH receptors in the testis and circulatory inhibin concentrations did not reach peak values until the testes were fully developed. Numbers of FSH receptors per testis, but not FSH concentration, were positively correlated (r = 0.65) with inhibin concentrations across the four stages of the testicular cycle. Near the end of testicular recrudescence early in the breeding season (Expt 2), relatively high FSH concentration was associated with increased abundance of FSH receptor mRNA (90%) and number of receptors (45%) in the testis and increased inhibin concentrations (50%), compared with when the testes were regressed. Moderate, physiological increases in testosterone secretion in immunized rams did not affect inhibin in either season. These results indicate that: (i) FSH stimulation of immunoactive inhibin secretion by Sertoli cells as testes recrudesce is via increases in secretion (early) and cognate receptors (late); (ii) FSH upregulates the synthesis of its own receptor late in recrudescence; and (iii) the positive correlation (r = 0.70) observed between circulatory testosterone and immunoactive inhibin does not reflect a causal relationship.

Pten regulates neuronal soma size: a mouse model of Lhermitte-Duclos disease

Somatic inactivation of PTEN occurs in different human tumors including glioblastoma, endometrial carcinoma and prostate carcinoma. Germline mutations in PTEN result in a range of phenotypic abnormalities that occur with variable penetrance, including neurological features such as macrocephaly, seizures, ataxia and Lhermitte-Duclos disease (also described as dysplastic gangliocytoma of the cerebellum). Homozygous deletion of Pten causes embryonic lethality in mice. To investigate function in the brain, we used Cre-loxP technology to selectively inactivate Pten in specific mouse neuronal populations. Loss of Pten resulted in progressive macrocephaly and seizures. Neurons lacking Pten expressed high levels of phosphorylated Akt and showed a progressive increase in soma size without evidence of abnormal proliferation. Cerebellar abnormalities closely resembled the histopathology of human Lhermitte-Duclos disease. These results indicate that Pten regulates neuronal size in vivo in a cell-autonomous manner and provide new insights into the etiology of Lhermitte-Duclos disease.

Combined effect of follicle-follicle interactions and declining follicle-stimulating hormone on murine follicle health in vitro

Follicle selection occurs throughout an adult female's reproductive life, with selected, dominant follicle(s) developing to the preovulatory stage whereas the remaining, subordinate follicles within the growing cohort instead undergo atresia and die. To date, most research into follicle dominance has concentrated on its endocrine regulation, although it seems likely that intraovarian mechanisms are also involved in its regulation. We demonstrate here that the response of singly cultured murine follicles to declining concentrations of FSH depends on their developmental stage, with follicles at an earlier stage of development being much more susceptible than mature follicles to a lowering of FSH levels. We then extrapolate this information to follicle cocultures, in which a large dominant follicle was grown with a small subordinate follicle in a manner that maintained a dominant/subordinate relationship, with follicle health assessed by a terminal transferase-mediated 2'-deoxyuracil 5'-triphosphate nick end-labeled reaction on whole-follicle mounts. Our investigations show a combined negative effect of coculture and FSH withdrawal on small subordinate follicles, such that subordinate follicles cocultured with dominant follicles and subjected to a lowering of FSH levels during the culture period exhibit a greatly increased incidence of apoptosis in the granulosa cells (750% increase) compared with that exhibited by the dominant follicles (97% increase). We suggest that a similar interaction between endocrine and intraovarian factors regulates follicular dominance in vivo, such that dominant follicles, in addition to bringing about a fall in FSH levels via the hypothalamic-pituitary axis, exert local, direct effects on subordinate follicles, with both of these influences combining to induce atresia in subordinate follicles.

Nucleoside analogues as highly potent and selective inhibitors of herpes simplex virus thymidine kinase

A series of carboxamide derivatives of 5'-amino-2',5'-dideoxy-5-ethyluridine has been prepared as inhibitors of HSV-TK (herpes simplex virus thymidine kinase). The most potent compounds were derived from xanthene, thioxanthene and dihydroanthracene carboxylic acids. The lead compounds show subnanomolar IC(50) values against HSV TKs.

EWS/FLI alters 5'-splice site selection

The chimeric gene EWS/FLI is present in at least 85% of Ewing's sarcomas as a result of chromosomal translocations. The resulting fusion protein contains the N terminus of the RNA-binding protein EWS and the ETS DNA-binding domain of the transcription factor FLI-1. Although EWS/FLI binds DNA and activates transcription, both EWS and EWS/FLI also interact with SF1 and U1C, essential components of the splicing machinery. Therefore, we tested the ability of EWS and EWS/FLI to alter 5'-splice site selection using an E1A gene in vivo splicing assay. We found that EWS/FLI, but not EWS, interfered with heterogeneous nuclear ribonucleoprotein A1-dependent splice site selection of E1A. Mutational analysis of EWS/FLI revealed that the ability to affect pre-mRNA splicing coincided with transforming activity. Therefore, EWS/FLI has the ability to influence splicing as well as transcription.

PTEN induces G(1) cell cycle arrest and decreases cyclin D3 levels in endometrial carcinoma cells

Inactivating mutations in the PTEN tumor suppressor gene occur in approximately 30-50% of endometrial carcinomas. PTEN is a phosphatase that negatively regulates the phosphoinositide 3-kinase signaling pathway, including the downstream effector AKT. To evaluate the role of PTEN in endometrial growth regulation, we expressed wild-type or mutant PTEN in endometrial carcinoma cell lines. As expected, expression of exogenous PTEN decreased levels of activated AKT in all cell lines examined. However, PTEN induced a G(1) cell cycle arrest specifically in endometrial carcinoma cells that lack endogenous wild-type PTEN. Growth of cells containing wild-type PTEN was unaffected by exogenous PTEN expression. Growth arrest required a functional phosphatase domain but not the PDZ interaction motif of PTEN. Overall levels of CIP/KIP and INK4 family members, the known inhibitory regulators of the G(1) phase of the cell cycle, were unchanged. However, PTEN induced a specific reduction of cyclin D3 levels and an associated increase in the amount of the inhibitor p27(KIP1) complexed with CDK2. Enforced expression of cyclin D3 abrogated the PTEN-induced cell cycle arrest. Although PTEN signaling directly regulates p27(KIP1) levels in some settings, in endometrial carcinoma cells, PTEN expression indirectly regulated p27(KIP1) activity by modulating levels of cyclin D3. These data support multiple mechanisms of PTEN-induced cell cycle arrest.

Parathyroid hormone, haematological and biochemical parameters in relation to dental disease and husbandry in rabbits

During a two-year period between 1995 and 1997, over 80 blood samples were collected from pet rabbits in order to investigate an apparent osteodystrophy affecting the skulls of rabbits with acquired dental disease. A series of haematological and biochemical analyses relating to calcium metabolism were performed and samples were taken for parathyroid hormone (PTH) assay. The rabbits were categorised according to the condition of their teeth and the manner in which the pets were kept. PTH concentrations were higher and calcium concentrations lower in hutch-kept rabbits with advanced dental disease in comparison with those kept in free-range conditions. No dental problems were detected in the free-range rabbits on radiological or clinical examination. During the course of the study, differences in haematological pictures and albumin values emerged among rabbits kept under the different husbandry regimes. Complete blood counts from free-range rabbits were comparable with laboratory reference ranges, whereas there were significantly lower red cell and lymphocyte counts in rabbits exhibiting advanced dental disease. Serum albumin values were significantly higher in rabbits kept in free-range conditions than in those with advanced dental disease or those unaffected by dental disease but kept in hutches. Rabbits kept in hutches showed trends towards anaemia and lymphopenia. Results indicated that acquired dental disease of pet rabbits is related to husbandry and is associated with alterations in calcium metabolism.

Characterization of an alternatively spliced AATYK mRNA: expression pattern of AATYK in the brain and neuronal cells

The AATYK gene encodes a tyrosine kinase whose expression is up-regulated during the apoptosis and differentiation of 32Dcl3 myeloblastic cells. Because high levels of AATYK mRNA have also been detected in the brain, and because these transcripts differ in size from that observed in the 32Dcl3 cell line, it was of interest to determine whether this gene encodes mRNAs that are alternatively spliced and whether these mRNAs are expressed in a tissue-specific manner. We have isolated a novel, alternatively spliced AATYK mRNA using cDNA library screening and RT-PCR, whose expression is readily detected in the brain but not myeloid cells. Western blot analysis revealed that the AATYK protein was expressed in virtually all regions of the adult rat brain in which neurons are present, including olfactory bulb, forebrain, cortex, midbrain, cerebellum and pons. Immunohistochemical labeling of adult brain sections showed the highest levels of AATYK expression in the cerebellum and olfactory bulb. Expression of AATYK was also up-regulated as a function of RA-induced neuronal differentiation of p19 embryonal carcinoma cells, supporting a role for this protein in mature neurons and neuronal differentiation.

Role of ascorbic acid in promoting follicle integrity and survival in intact mouse ovarian follicles in vitro

Ascorbic acid has three known functions: it is necessary for collagen synthesis, promotes steroidogenesis and acts as an antioxidant. Within the ovary, most studies have concentrated on the role of ascorbic acid in luteal formation and regression and little is known about the function of this vitamin in follicular growth and development. Follicular growth and development were investigated in this study using an individual follicle culture system that allows the growth of follicles from the late preantral stage to Graafian morphology. Follicles were isolated from prepubertal mice and cultured for 6 days. Control media contained serum and human recombinant FSH. Further groups of follicles were cultured in the same media but with the addition of ascorbic acid at concentrations of either 28 or 280 micromol l(-1). Addition of ascorbic acid at the higher concentration significantly increased the percentage of follicles that maintained basement membrane integrity throughout culture (P < 0.001). Ascorbic acid had no effect on the growth of the follicles or on oestradiol production. Metalloproteinase 2 activity tended to increase at the higher concentration of ascorbic acid and there was a significant concomitant increase in the activity of tissue inhibitor of metalloproteinase 1 (P < 0.01). Follicles cultured without the addition of serum but with FSH and selenium in the culture media underwent apoptosis. Addition of ascorbic acid to follicles cultured under serum-free conditions significantly reduced apoptosis (P < 0.05). From these data it is concluded that ascorbic acid is necessary for remodelling the basement membrane during follicular growth and that the ability of follicles to uptake ascorbic acid confers an advantage in terms of granulosa cell survival.

Cardiorespiratory and thermoregulatory response of working in fire-fighter protective clothing in a temperate environment

The cardiorespiratory and thermal responses of two intensities of treadmill exercise were compared for brief periods (12 min) in fire ensemble (FE) but without self contained breathing apparatus, and sports ensemble (SE), in a temperature environment. A further experiment explored the responses of subjects exercising in FE over a prolonged period (60 min). Eighteen male fire-fighters wearing either FE or SE walked on a level treadmill for 6 min at 5 km x h(-1) increasing to 7 km x h(-1) for 6 min. Following a recovery interval of 1 h, the exercise protocol was repeated in the second ensemble; the order of ensemble was balanced. Heart rate (HR), rectal temperature (Tre), VO2 max and rating of perceived exertion (RPE) were monitored continuously under both ensembles. At 7 km x h(-1), VO2 was significantly higher (p<0.05) in FE (36.1 and 39.9 ml x kg(-1) x min(-1)) than in SE and represented 74% VO2 max. There were no changes Tre. In experiment 2, following a rest interval of at least 36 h, eight subjects in FE walked on the treadmill at 6 km x h (gradient 10%) for 60 min also in temperate conditions, where HR, Tre and RPE were recorded at 10-min intervals. During the 60-min exercise in FE, HR reached 161 beats x min(-1) and Tre increased to 38.3 degrees C. Despite considerable subject discomfort, Tre remained below dangerous levels (38.4 degrees C). When RPE were compared with a physiological strain index (PSI) calculated from Tre and HR data over 60 min, there was no significant difference (p<0.05) with a correlation coefficient (r) of 0.98. The results suggest that RPE and PSI are closely related when exercise is sufficiently prolonged or intense to elevate Tre and HR in fire-fighters wearing FE in temperate conditions. If further investigation confirms this relationship for hot humid conditions in which fire-fighters operate, then with training, it may provide individuals with a valid measure of dangerous levels of perceived heat strain.

The splicing factor U1C represses EWS/FLI-mediated transactivation

EWS is an RNA-binding protein involved in human tumor-specific chromosomal translocations. In approximately 85% of Ewing's sarcomas, such translocations give rise to the chimeric gene EWS/FLI. In the resulting fusion protein, the RNA binding domains from the C terminus of EWS are replaced by the DNA-binding domain of the ETS protein FLI-1. EWS/FLI can function as a transcription factor with the same DNA binding specificity as FLI-1. EWS and EWS/FLI can associate with the RNA polymerase II holoenzyme as well as with SF1, an essential splicing factor. Here we report that U1C, one of three human U1 small nuclear ribonucleoprotein-specific proteins, interacts in vitro and in vivo with both EWS and EWS/FLI. U1C interacts with other splicing factors and is important in the early stages of spliceosome formation. Importantly, co-expression of U1C represses EWS/FLI-mediated transactivation, demonstrating that this interaction can have functional ramifications. Our findings demonstrate that U1C, a well characterized splicing protein, can also function in transcriptional regulation. Furthermore, they suggest that EWS and EWS/FLI may function both in transcriptional and post-transcriptional processes.

Design, synthesis, and biological evaluation of fluoronitrophenyl substituted folate analogues as potential inhibitors of GAR transformylase and AICAR transformylase

The examination results of a novel series of potential inhibitors of glycinamide ribonucleotide transformylase (GAR Tfase) and aminoimidazole carboxamide transformylase (AICAR Tfase) are reported. These agents incorporate an electrophilic fluoronitrophenyl group that can potentially react with an active site nucleophile or the substrate GAR/AICAR amine via nucleophilic aromatic substitution.

Cloning of murine G1RP, a novel gene related to Drosophila melanogaster g1

To study the nature of genes that are induced during the apoptotic death of myeloid precursor cells, we performed representational difference analysis (RDA) using 32Dcl3 myeloblastic cells that were deprived of IL-3 for 24h. We have isolated a novel cDNA (g1-related protein, G1RP) that is homologous to g1, a Drosophila melanogaster zinc-finger protein that is expressed in the mesoderm. Northern blot analysis using RNAs derived from 32Dcl3 cells that have been grown in the absence of IL-3 demonstrates that the G1RP message is upregulated in these cells following the removal of IL-3, suggesting that this gene may regulate growth factor withdrawal-induced apoptosis of myeloid precursor cells.

Conformationally restricted analogues designed for selective inhibition of GAR Tfase versus thymidylate synthase or dihydrofolate reductase

The synthesis and evaluation of a series of conformationally restricted analogues of 10-formyl-tetrahydrofolate as potential inhibitors of glycinamide ribonucleotide transformylase (GAR Tfase) or aminoimidazole carboxamide transformylase (AICAR Tfase) are reported.

Using an AraC-based three-hybrid system to detect biocatalysts in vivo

Recent methods to create large libraries of proteins have greatly advanced the discovery of proteins with novel functions. However, one limitation in the discovery of new biocatalysts is the screening or selection methods employed to find enzymes from these libraries. We have developed a potentially general method termed QUEST (QUerying for EnzymeS using the Three-hybrid system), which allows the construction of an easily screened or selected phenotype for, in theory, any type of enzymatic reaction. The method couples the in vivo concentration of an enzyme's substrate to changes in the transcriptional level of a reporter operon. Using the arabinose operon activator AraC, we constructed a system capable of detecting the fungal enzyme scytalone dehydratase (SD) in bacteria, and demonstrated its sensitivity and usefulness in library screening.

Fine-needle aspiration cytology findings in 214 cases of nonparotid lesions of the head

The use and limitations of fine-needle aspiration (FNA) of lesions of the parotid gland are known, but those of nonparotid lesions of the head have been described only sporadically. We conducted this study to evaluate the utility of FNA and to analyze the causes of diagnostic discrepancies for these lesions. A total of 6,898 FNAs of different sites was performed at our institutions between January 1991-August 1998, and 214 (3.1%) of the cases were FNAs of nonparotid lesions of the head. The most common diagnosis of nonparotid lesions was squamous-cell carcinoma, in 22% (n = 48), and the most common site aspirated was the scalp, in 34% (n = 73). Lipomas and keratinous cysts comprised 5% (n = 9) of the total. A statistical analysis was conducted on 98 paired cytology and histology (n = 83) and cytology and flow cytometry (n = 15) specimens (70 malignant and 28 benign). FNA recognized the malignant and benign nature of the lesion in 60 and 26 cases, respectively with 86% sensitivity 93% specificity and 88% accuracy. Causes of false-negative FNA diagnoses (n = 10) included sampling error (n = 6), bloody smears with scant cellularity (n = 3), and bland cytomorphology (n = 1). Florid granulation tissue and a mucocele of the tongue accounted for the two false-positive cases. We conclude that FNA is an effective tool for triage of surgery candidates with nonparotid lesions of the head. Adequate samples with sufficient cellularity are required for avoiding false-negative diagnoses. Occasionally, tissue biopsy is needed for diagnosis of equivocal cases.

Crohn disease arthropathy: antigens in synovial fluid share epitopes with strains of two species of viridans streptococci

BACKGROUND

There is evidence to suggest that Crohn disease is caused by an immunologic response to an unknown intestinal luminal antigen, probably of bacterial origin. The reported demonstration of yersinia antigen in the synovial fluid of patients with yersinosis therefore prompted a search for bacterial antigens in the synovial fluid of patients with Crohn arthropathy.

METHODS

Antisera were raised in rabbits to synovial fluids obtained from seven patients with Crohn arthropathy and from seven 'control' subjects with other forms of arthropathy. These antisera were used to probe sonicates of the bacteria cultured from the gastric juice of patients with gastric Crohn disease.

RESULTS

The antisera made from the Crohn synovial fluids, but none of those made from the controls, reacted uniquely with antigens in sonicates of strains of two species of viridans streptococci (Streptococcus parasanguis and an atypical S. oralis) isolated from four of the five patients with gastric Crohn disease.

CONCLUSIONS

These findings suggest that the arthropathy of Crohn disease and, possibly, the intestinal disease itself may involve an immunologically mediated inflammatory response to these antigens.

Transforming activity of EWS/FLI is not strictly dependent upon DNA-binding activity

In approximately 85% of Ewing sarcomas, chromosomal translocations give rise to the chimeric gene EWS/FLI, encoding the N-terminus of the RNA binding protein EWS fused to the DNA-binding domain of the ETS protein FLI-1. EWS/FLI is a stronger transcriptional activator than wild-type FLI-1, although both proteins bind to the same DNA sequences in vitro. In addition, EWS/FLI, but not FLI-1, is a transforming oncogene in NIH3T3 fibroblasts. EWS/FLI is thought to transform through its ability to deregulate the expression of target genes. We introduced several point mutations into the ETS domain of EWS/FLI that abolished DNA-binding activity. Although two of these mutations disrupted the transforming activity of EWS/FLI, one mutated protein containing a substitution of isoleucine 347 with glutamic acid (I347E) retained diminished transforming activity. In addition, EWS/FLI I347E did not activate expression of the endogenous EWS/FLI target gene manic fringe (MFNG). These studies demonstrate that a portion of the oncogenic activity of EWS/FLI is independent of FLI DNA-binding activity.

The role of intra-ovarian interactions in the regulation of follicle dominance

The processes that precisely control the selection of ovulatory follicles from a growing cohort are poorly understood. This reduction in follicle number occurs through several phases of selection, consequently we limit the use of the term 'selection' to the first major reduction of growing follicles, at the pre- to early antral stage. The final process of selection, achieving the appropriate ovulatory number, is referred to as 'dominance'. We discuss possible mechanisms that could bring about these reductions and highlight intra-ovarian involvement, particularly via follicle-follicle interactions. Analogies are drawn between local ovarian events and processes commonly reported in the determination of cell fate in developmental biology. Two facets of intra-follicular interactions are proposed: initially that follicle-follicle interactions mediate early selection processes at the preantral stage, and later that during antral development dominant follicles directly affect the fate of the subordinate cohort members.

Modulation of life and death by the TNF receptor superfamily

The tumor necrosis factor receptor (TNFR) superfamily represents a growing family, with over 20 members having been identified thus far in mammalian cells. These proteins share significant homologies in their extracellular ligand binding domains and intracellular effector (death) domains. These receptors appear to transmit their signals via protein-protein interactions, which convey either a death or survival signal. Isolation and characterization of death domain containing proteins (TRADD, FADD/MORT-1, RIP), TRAF domain containing proteins (TRAF1-6) as well as new members and adaptor proteins such as DAXX have provided new insights to our understanding of signaling mechanisms associated with this family of receptors. While the death signals seem to be associated with the activation of both the caspase and JUN kinase pathways, the survival signals are mediated via the activation of the NF-kappaB pathway.

The role of v-Fgr myristoylation and the Gag domain in membrane binding and cellular transformation

The v-fgr oncogene encodes a chimeric oncoprotein composed of feline sarcoma virus (FeSV)-derived gag and cellular-derived actin and c-Fgr sequences. v-Fgr is myristoylated and membrane bound, two criteria which must be met for src kinases to induce cellular transformation. Although inhibition of myristoylation resulted in a decreased ability of v-Fgr to sediment with membranes from an NIH-3T3 P100 fraction, deletion of the gag domain caused nearly all of the protein to remain unbound and cytosolic. Systematic deletions within gag indicate that while amino acids 3 through 9 are critical determinants of myristoylation and/or define a domain which directs membrane localization, these residues cooperate with additional gag sequences when anchoring the protein to the plasma membrane. Furthermore, nonmyristoylated and/or cytoplasmic variants of v-Fgr failed to induce anchorage-independent growth of NIH-3T3 cells, indicating that proper subcellular localization of v-Fgr is a key factor in its ability to induce transformation.

Changes in the capacity of the vagina and the compliance of the vaginal wall in ovariectomized, normal cyclical and pregnant ewes, before and after treatment with exogenous oestradiol and progesterone

The 'capacity' of the vagina and the compliance of the vaginal wall was measured in bilaterally ovariectomized ewes (n = 7) before and after treatment with exogenous oestradiol and progesterone; in nulliparous ewes (n = 7) at oestrus (Day 0) and dioestrus (Day 10) and during pregnancy, and in another group of pregnant ewes (n = 15) treated with exogenous oestradiol and progesterone. Measurements were remarkably consistent within individual animals but there were considerable differences between individual animals. The 'vaginal capacity' and the compliance of the vaginal wall were greater at oestrus than during dioestrus. In the same seven ewes, which were studied during their first and second pregnancies, the 'capacity' of the vagina increased whereas the compliance of the vaginal wall declined; from 90 days to term both parameters remained fairly constant. For the first 2 months of gestation the vaginal capacity was greater in year 2 than year 1 but this was reversed during the last 3 months. The compliance of the vaginal wall was significantly greater (P < 0.0001) in year 2 than year 1 at all stages of pregnancy. In ovariectomized ewes, progesterone only significantly increased the vaginal capacity at the highest dose rate (viz. 100 mg); the compliance of the wall was reduced at the 25 and 50 mg dose rates. Oestradiol produced an inconsistent dose response effect; whilst 5 mg and 20 mg had no effect upon the vaginal capacity, the 10 mg dose rate significantly reduced it. Similarly, the highest and lowest dose rates reduced the compliance of the vaginal wall but the 10 mg dose rate increased it. At 90 and 120 days of gestation, both 5 mg oestradiol and 100 mg progesterone increased the vaginal capacity but reduced the compliance.

Diagnostic value of brush cytology in the diagnosis of duodenal, biliary, and ampullary neoplasms

Endoscopy is a valuable tool in the diagnosis and management of duodenal lesions and biliary strictures. We assessed the value of cytology in the evaluation of these lesions and analyzed the causes of discrepancy among clinical, histologic, and cytologic parameters. The study included 118 patients with duodenal ulcers, ampullary neoplasms, or biliary strictures who were examined between 1975 and 1995; 120 cytologic examinations were performed. The specimens included brushings of the duodenum (DB, n = 50), ampulla (AB, n = 32), and biliary ducts (BB, n = 38). Endoscopic biopsies performed concurrently included the duodenum (n = 37), the ampulla (n = 22), and the biliary ducts (n = 23). Comparison of cytologic and histologic results showed the following sensitivity and specificity: DB, 40% and 97%, respectively; AB, 100% each; BB, 75% and 93%, respectively. The DB, AB, and BB revealed malignant neoplasms in 2 of 5, 7 of 7, and 6 of 8 cases, respectively. Twenty-three duodenal neoplasms were diagnosed by either modality and included 11 adenocarcinomas, 9 villous tumors, 2 metastatic renal cell carcinomas, and 1 large cell non-Hodgkin's lymphoma. Endoscopic brush cytology is an effective means of diagnosing ampullary neoplasms, and it complements tissue biopsy in cases of bile duct stricture. Location, predominance of tumor-induced stroma, an extramucosal growth pattern, sampling error, and interpretative experience influence the diagnostic evaluation. Cytologic diagnosis of an adenoma does not exclude an underlying malignant neoplasm in ampullary tumors. In some instances, it may be difficult to distinguish between villous tumors with severe dysplasia and adenocarcinomas by cytology alone.

AATYK: a novel tyrosine kinase induced during growth arrest and apoptosis of myeloid cells

Apoptosis, or programmed cell death, is a process where developmental or environmental stimuli activate a genetic program to implement a series of events that culminate in cell death. To study the nature of genes that are induced during the apoptotic death of myeloid precursor cells, we utilized the 32Dcl3 cell line, which is derived from normal mouse bone marrow, is non-tumorigenic and diploid. These cells are strictly dependent on IL-3 for growth and apoptose when deprived of IL-3. However, when these cells are transferred to medium containing G-CSF, the cell number increases 4-5-fold and after 12 days the entire population is differentiated into granulocytes followed by apoptotic death. In our search for genes that are induced during apoptosis and/or terminal differentiation of 32Dcl3 cells, we identified a novel gene termed AATYK (Apoptosis Associated Tyrosine Kinase), whose expression is dramatically upregulated during IL-3 deprivation as well as G-CSF-induced terminal differentiation. In this report, we describe the sequence of the cDNA clone, derived from the mRNA transcript of this gene. These studies show that this gene encodes a protein with a tyrosine kinase domain at the N-terminal end and a proline-rich domain at the C-terminal end. We also report that the expression of this gene is blocked in v-abl or bcr-abl transformed myeloid cells which are unable to apoptose when grown in the absence of IL-3. However, AATYK expression is induced in 32D cells transformed by the v-abl gene when these cells are incubated in the presence of DMSO, which induces growth arrest and apoptotic death of the cells. On the other hand, DMSO fails to induce apoptosis or AATYK expression in 32D cells transformed by the bcr-abl oncogene, suggesting that AATYK expression may be a necessary pre-requisite for the induction of growth arrest and/or apoptosis of myeloid precursor cells.

PhoP/Q regulated genes in Salmonella typhi identification of melittin sensitive mutants

Many of the genes (pags (phoP activated genes) and prgs (phoP repressed genes)) regulated by the PhoP and PhoQ proteins (PhoP/Q) are necessary for survival of Salmonella typhimurium in murine macrophages and pathogenesis in mice. Although a great deal is known about the S. typhimurium phoP/Q regulon, little has been done with the human specific pathogen S. typhi, prompting us to investigate S. typhi phoP/Q regulated genes. Isogenic phoP12 (null) and phoP24 (constitutive) strains were constructed in S. typhi Ty2 and S. typhimurium C5 strains. Comparison of whole cell proteins from these strains by SDS-PAGE showed differences in both the number and molecular mass of PhoP/Q regulated proteins. This suggested that S. typhi and S. typhimurium may have different PhoP/Q regulated proteins and/or that their regulation may be different. A genetic procedure was developed to isolate mutations in PhoP/Q regulated genes. This involved random MudJ transposon mutagenesis of a phoP12 mutant, creating lacZ-gene fusions, and screening for Lac+ or Lac- colonies. A mobilizable plasmid carrying the phoP24 mutant gene was conjugated into these insertion mutants. Those that changed from Lac- to Lac+ were inferred to be pag::MudJ insertions and those that changed from Lac+ to Lac- were inferred to be prg::MudJ insertions. Five mutants with PhoP/Q regulated MudJ fusions were found by this scheme. The mutations were termed pqa (PhoPQ activated) and pqr (PhoPQ repressed) to distinguish them from other PhoP/Q regulated genes. The pqa/pqr::MudJ mutations were transduced into S. typhi phoP+ and phoP24 strains by Vi-l phage transduction. Characterization of the mutants (Southern blot analysis, beta-galactosidase activity on indicator plates and in liquid cultures) strongly suggested that their MudJ insertion mutations were in five different genes. Further characterization involved determining cationic peptide sensitivity and mouse virulence. Two mutants were found to be sensitive to the antimicrobial peptide melittin.

Transducers of life and death: TNF receptor superfamily and associated proteins

Signal transduction pathways which are initiated by members of the TNF superfamily utilize receptors which are devoid of intrinsic catalytic activity. Isolation and characterization of death domain (TNF-RI, Fas, TRADD, FADD/MORT-1, RIP) and TRAF domain-containing proteins (TRAF-1, TRAF-2, TRAF-3) have partially bridged a large molecular gap within one of several signaling pathways which originate at the plasma membrane and terminate in the nucleus. The ability of these two protein families to selectively dimerize and bind to related receptors allows them to govern diverse cellular responses which culminate in cellular proliferation, differentiation, effector functions, and apoptosis.