Surgical Trainee Perspectives on the Opioid Crisis: The Influence of Explicit and Hidden Curricula

OBJECTIVE

In order to effectively create and implement an educational program to improve opioid prescribing practices, it is important to first consider the unique perspectives of residents on the frontlines of the opioid epidemic. We sought to better understand resident perspectives on opioid prescribing, current practices in pain management, and opioid education as a needs assessment for designing future educational interventions.

DESIGN

This is a qualitative study using focus groups of surgical residents at 4 different institutions.

SETTING

We conducted focus groups using a semistructured interview guide in person or over video conferencing. The residency programs selected for participation represent a broad geographic range and varying residency sizes.

PARTICIPANTS

We used purposeful sampling to recruit general surgery residents from the University of Utah, University of Wisconsin, Dartmouth-Hitchcock Medical Center, and the University of Alabama at Birmingham. All general surgery residents at these locations were eligible for inclusion. Participants were assigned to focus groups by residency site and their status as junior (PGY-2, PGY-3) or senior resident (PGY-4, PGY-5).

RESULTS

We completed 8 focus groups with a total of 35 residents included. We identified 4 main themes. First, residents relied on clinical and nonclinical factors when making decisions about opioid prescribing. However, hidden curricula based on unique institutional cultures and attending preferences heavily influenced residents' prescribing practices. Second, residents acknowledged that stigma and biases towards certain patient groups influenced opioid prescribing practices. Third, residents encountered barriers within their health systems to evidence-based opioid prescribing. Fourth, residents did not routinely receive formal education on pain management or opioid prescribing. Residents recommended several interventions to improve the current state of opioid prescribing, including standardized prescribing guidelines, improved patient education, and formal training during the first year of residency.

CONCLUSIONS

Our study highlighted several areas of opioid prescribing that can be improved upon through educational interventions. These findings can be used to develop programs aimed at improving residents' opioid prescribing practices, both during and after training, and ultimately the safe care of surgical patients.

ETHICS STATEMENT

This project was approved by the University of Utah Institutional Review Board, ID # 00118491. All participants provided written informed consent.

Deep sleep and beeps II: Sleep quality improvement project in general surgery patients

BACKGROUND

Poor sleep leads to poor health outcomes. Phase I of our sleep quality improvement project showed severe sleep disturbance in the ward setting. We implemented a novel PostOp Pack to improve sleep quality.

METHODS

Patients underwent elective, general surgery procedures. Fitbit trackers measured total sleep time. Patients completed the inpatient Richards-Campbell Sleep Questionnaire, which combines 5 domains into a cumulative score (0-100). Patients completed the outpatient Pittsburgh Sleep Quality Index preoperatively and postoperatively. Patients received the PostOp Pack, which included physical items and a sleep-protective order set to reduce nighttime awakenings. Patients from phase I served as the historical control. The primary outcome was the percentage of patients with Richards-Campbell Sleep Questionnaire total sleep score ≥50. The secondary outcomes included the mean Richards-Campbell Sleep Questionnaire domain scores and Fitbit total sleep time.

RESULTS

A total of 49 patients were compared with 64 historical controls. The percentage of patients with a total sleep score ≥50 was significantly higher in patients receiving a PostOp Pack versus historical control (69% vs. 44%, difference 26%, 95% confidence interval 6.1-45%, P = .01). The mean Richards-Campbell Sleep Questionnaire Total Sleep Score was significantly higher in patients with a PostOp Pack (62 vs 49, mean difference 13, 95% confidence interval 6-21, P ≤ .01). The PostOp Pack Richards-Campbell Sleep Questionnaire domain scores were significantly higher in various areas: Sleep Latency (68 vs 49, P ≤ .01), Awakenings (56 vs 40, P = .01), Sleep Quality (61 vs 49, P = .02), and Noise Disturbance (70 vs 59, P = .04). Of all patients, 92% would use PostOp Pack again in a future hospitalization. No patients had a failure to rescue event with PostOp Pack. The mean total sleep time was significantly improved with PostOp Pack on night 1 (6.4 vs 4.7 hours, P = .03).

CONCLUSION

The PostOp Pack improves inpatient sleep quality and is safe.

Physicians perceive that ostomates have decreased quality of life but not overall health: An international survey of physicians

AIM

The aim of this work was to evaluate physicians' perceptions of ostomates' quality of life (QoL) and comfort of care among an international sample of physicians caring for ostomates.

METHOD

This was a cross-sectional survey study. We conducted a survey of primary care physicians (PCP), gastroenterologists (GI), and general surgeons (GS) from three continents using the SERMO online physician platform. We piloted the survey for content, clarity and domain development using a pilot sample of physicians from each speciality before use. We summarized responses to questions related to physician comfort of ostomate care with descriptive statistics. We conducted multiple logistic regression with the primary outcome of physician perception of ostomate QoL.

RESULTS

A total of 617 physicians (PCP 264, GI 176, GS 177) completed the survey representing North America, Europe and Australia similarly. The average age was 46 years and 21% were women. Ninety per cent of physicians care for an ostomate at least once per month. Eighty eight per cent had access to enterostomal nurses. Eighty two per cent of physicians believed that ostomates have decreased QoL. Forty seven per cent believed that ostomates have decreased overall health. Almost half of respondents answered incorrectly to a 'bogus question' citing fake clinical evidence supporting a negative impact of ostomies on social relationships. Increased physician comfort in ostomy care (OR 1.30, p = 0.04) and US-based physicians (OR 1.75, p = 0.01) were associated with increased odds of answering that ostomates have no decreased QoL.

CONCLUSION

Among a diverse international sample, most physicians believe that ostomates have decreased QoL but not overall health. Physician implicit bias, physician comfort and geographical variability account for these findings. Targeted efforts to increase physician comfort in ostomate care and establish universal best practices is needed.

Implementation of a Standardized Sub-Intern Curriculum Improves Confidence for those Entering a Surgical Residency

OBJECTIVE

Medical students often feel underprepared entering surgical residency. We have previously reported the results of a sub-intern needs assessment (SINA) which informed the creation of a standardized sub-internship curriculum. We aimed to determine if implementation of this curriculum into students' scheduled rotations would improve student confidence in their abilities related to the AAMC Core Entrustable Professional Activities for Entering Residency (CEPAERs).

DESIGN

We surveyed 4th year medical students during their surgery sub-internship. Sub-interns participated in a weekly series of 2-hour didactic sessions. We utilized interactive lectures and case scenarios addressing the pertinent topics identified in our previous needs assessment. The surveys were administered before and after the rotation and linked using unique identifiers. The surveys assessed confidence in each of the CEPAERs as well as the top 25 topics prioritized by our needs assessment. Self-reported confidence in each of the topics was measured using Likert scales (CEPAER scale 1-5, SINA scale 1-6). Pre- and post-curriculum confidence on a variety of topics were compared using paired t-tests.

SETTING

Geisel School of Medicine at Dartmouth/Dartmouth-Hitchcock Medical Center, a tertiary-care academic medical center.

PARTICIPANTS

Fourth year medical students participating in their general surgery sub-internship.

RESULTS

Twelve medical students participated in general and thoracic surgery sub-internships over the course of the study period. Ten (83%) participated in the didactic curriculum and they all completed both the pre- and postsurvey. 100% of the respondents agreed that the curriculum provided a useful supplement to their clinical experience. With respect to the CEPAERs, students reported improved confidence in 77% of the areas, with statistically significant increases occurring in the following areas: ability to prioritize a differential diagnosis (average Likert rating improved from 3.7 to 4.1, p = 0.04), comfort entering and discussing orders (2.9-3.8, p = 0.007), and overall preparedness to be a surgical intern (3.2-3.8, p = 0.02). Students also reported improvement in confidence in 92% of the basic intern responsibility topics, with statistically significant increases in maintenance fluid calculations (Likert rating 3.5-4.5, p = 0.001), repleting electrolytes (3.8-4.6, p = 0.01), interpretation of chest and abdominal x-rays (4-5, p = 0.02; 3.6-4.5, p=0.004, respectively), management of oliguria (3.2-3.8, p = 0.02), and time management/organization skills (4.5-5.4, p = 0.04).

CONCLUSIONS

Implementation of a standardized sub-intern curriculum improved student confidence in 33 of the 38 basic intern responsibilities, core Entrustable Professional Activities, and overall preparedness to be a surgical intern. While limited by a single institution design, we believe these results offer a new avenue for educating and preparing medical students for residency within their existing sub-internships.

Retrorectus mesh reinforcement of ileostomy site fascial closure: stoma closure and reinforcement (SCAR) trial phase I/II results

PURPOSE

Loop ileostomy (LI) is commonly employed during colorectal surgeries to reduce the consequences of anastomotic leak. Unfortunately, LI is associated with a 10-30% incisional hernia (IH) rate after closure. We hypothesized that prophylactic mesh reinforcement during LI takedown would safely prevent subsequent IH formation.

METHODS

This single-center, phase I/II prospective study evaluated adult patients undergoing LI closure after left-sided colorectal cancer procedures. After LI closure, the posterior rectus sheath was mobilized and reapproximated with absorbable suture. A reduced-weight, macroporous, polypropylene mesh (Softmesh, BD) was placed in the retrorectus position to allow 3 cm of overlap and secured with fibrin sealant. The anterior fascia was closed with slowly absorbable suture. CT images obtained for cancer surveillance were reviewed by a radiologist blinded to the study intervention to evaluate for evidence of hernia or surgical site occurrence (SSO).

RESULTS

Twenty patients were included with mean defect and mesh sizes of 11.2 cm² and 64.2 cm², respectively. Mean operative time for LI takedown and mesh augmented closure was 84 min with mesh implantation time being 16.4 min. Two patients were readmitted within 30 days for ileus, no patient required procedural intervention. Over a mean follow-up period of 20 ± 7 months, no SSO or hernias were observed clinically or on CT imaging.

CONCLUSION

In our small series, retromuscular mesh reinforcement of LI closure appears feasible, safe and effective. This mesh reinforcement approach should be further investigated to evaluate its long-term effectiveness.

Current Barriers in Robotic Surgery Training for General Surgery Residents

OBJECTIVE

To assess the current barriers in robotic surgery training for general surgery residents.

DESIGN

Multi-institutional web-based survey.

SETTING

9 academic medical centers with a general surgery residency.

PARTICIPANTS

General surgery residents of at least PGY-3 training level.

RESULTS

163 general surgery residents were contacted with 80 responses (49.1%). The most common responders were PGY-3s (38.8%) followed by PGY-5s (27.5%). The Northeast represented 42.5% of responses. Colorectal cases were the most common robotic case residents were involved in (51.3%). Residents' typical roles were assisting at the bedside (31.3%) and splitting time between assisting at the bedside and operating at the surgeon console (31.3%). 43% report to be either extremely or somewhat dissatisfied with their robotic surgery experience. 62.5% report they do not intend to integrate robotic surgery into their future practice. 93.8% of residents have a standardized robotic curriculum. 47.5% report using the simulator only during required didactic time with 52.5% having the robotic simulator conveniently located. The majority of residents report that the presence of dual consoles and first-assists in robotic cases enhance their robotic training (93% - 62%, respectively). 72.5% felt like they had more autonomy during laparoscopic cases and 96.8% of residents felt that an attendings' lack of experience impacted their time operating at the surgeon console.

CONCLUSIONS

General surgery residents report lack of effective OR teaching, real clinical experience, and simulated experience as main barriers in their robotic surgery training. Dual consoles and first-assistants are favorably looked upon. Lack of attending experience and comfort were universally negatively associated with resident participation. For residents interested in robotic surgery, advocating for more robust investment in dual consoles, first-assistants, and faculty development would likely improve their robotic surgery training experience. However, residency programs should consider whether robotic surgery should be a core competency of an already time restricted training paradigm.

Late and Long-term Symptom Management in Colorectal Cancer Survivorship

CASE SUMMARY

A 59-year-old previously healthy, asymptomatic man initially presented for his first screening colonoscopy. At this time, a friable, partially obstructing tumor was encountered in his proximal rectum. Final workup demonstrated a mrT2N1M0 upper rectal cancer. The patient went on to successfully complete total neoadjuvant chemoradiation therapy and was taken to the operating room for an uncomplicated robotic-assisted low anterior resection with primary anastomosis. His final pathology revealed an ypT2N1M0 rectal cancer, and he was subsequently followed in surveillance per National Comprehensive Cancer Network guidelines. At long-term follow-up visits he continued to report significant depressive symptoms and functional impairment. Despite aggressive medical management with fiber supplementation and antidiarrheal medications, the patient continued to struggle with bowel movement frequency and urgency. He reported having 4 to 6 clustered bowel movements during the day and 1 to 2 stools at night that significantly limited his ability to perform normal day-to-day activities.

A Targeted Needs Assessment for the Development of a Surgical Sub-internship Curriculum

OBJECTIVE

Medical students often feel inadequately prepared for the responsibilities of surgical internship because of insufficient exposure to resident responsibilities prior to starting residency. This lack of preparation may contribute to burnout and attrition early in residency. Sub-internships should provide these experiences. Significant variation, however, exists in the structure of these rotations. We conducted a targeted needs assessment to inform the development of a didactic curriculum to address gaps in the surgical sub-internship experience and better prepare students for general surgery residency.

DESIGN

A 25-item needs assessment survey was developed and distributed to senior medical students in their surgical sub-internship, current junior residents, and prior students (alumni) from the past 4 years who matched into general surgery residencies at other institutions.

SETTING

Geisel School of Medicine at Dartmouth/Dartmouth-Hitchcock Medical Center, a tertiary-care academic medical center.

PARTICIPANTS

Nine senior medical students; 12 current residents and 14 alumni, including 9 PGY-1, 13 PGY-2, and 4 PGY-3 residents.

RESULTS

The topics rated most important by medical students were floor management topics, specifically lines, tubes, and drains, hypotension, post-operative fever, chest pain, oliguria, and post-operative pain. In contrast, there was a wider variety of topics rated highly by residents. Residents emphasized non-technical communication and documentation skills. Residents at every training level rated presenting patients on rounds as the most important skill for incoming interns to acquire, whereas only one-third of medical students considered this to be an essential topic.

CONCLUSIONS

Medical students rank management of common clinical problems as the most critical aspect in their preparation for residency. Residents recognized these topics as important, but also placed high emphasis on non-technical communication and documentation skills. The findings from this need's assessment can be used to guide content structure for a sub-intern curriculum.

Long-term bowel function patient-reported outcomes after successful chemoradiation for carcinoma of the anal canal

AIM

We aimed to evaluate long-term changes in patient-reported bowel function from presentation of anal canal squamous cell carcinoma (SCC) successfully treated with the modified Nigro protocol using a patient-reported outcome measure for bowel function.

METHOD

This is a retrospective study of prospectively collected patient-reported outcomes for bowel function. We included patients that were successfully treated with the modified Nigro protocol for anal SCC and had completed the Colorectal Functional Outcomes (COREFO) questionnaire at presentation, following the modified Nigro treatment (post-Nigro), and at subsequent surveillance visits (medium and long term). We compared the differences in mean domain and total COREFO scores using a paired t test for each paired time point.

RESULTS

Twenty-seven patients met inclusion criteria. Time from completion of the modified Nigro was post-Nigro at 3-6 months, medium-length follow-up at 8-12 months and long-term follow-up at 12-18 months. There was significant improvement in the stool-related aspects domain (pain, bleeding and anal skin irritation) from presentation to our short- and medium-length follow-up (42.5 to 23.7, P = 0.01). There was worsening in the frequency domain in the medium term (7.23 to 14.5, P = 0.02). There were no differences in any other domain or time point.

CONCLUSION

Global bowel function does not appear to change following successful treatment of anal canal SCC with the modified Nigro protocol in the long term. There are some improvements in stool-related aspects and worsening in bowel movement frequency at medium-length follow-up. These findings should help surgeons counsel patients with regard to bowel function expectations for those with anal canal SCC in the long term.

Poor Baseline Health of IBD Patients at Presentation to a Surgeon: Results From a Patient-Reported Outcomes Database

Background

Many patients with inflammatory bowel disease (IBD) are referred to surgeons when medical treatments are ineffective, signifying poor disease control. We aimed to assess the association of IBD diagnosis with physical and mental health upon presentation to a colorectal surgeon.

Methods

We included all new patients presenting to colorectal surgery clinic over 1.5 years. During registration, patients completed the PROMIS Global-10, a validated outcome measure assessing physical and mental health. We grouped patients by diagnosis: IBD, anorectal, benign colorectal, and malignancy. Details on IBD patients were obtained via chart review. We evaluated the interaction between PROMIS scores and diagnosis through ANOVA analysis and post hoc Tukey-Kramer pairwise comparison. We estimated the strength of association of age, sex, and visit diagnosis with poor physical and mental health (PROMIS: -1 SD) through logistic regression.

Results

Eight hundred ninety-seven patients were included. The cohort was as follows: IBD (99) (Crohn = 73; ulcerative colitis = 26), anorectal (378), benign colorectal (224), and malignancy (196). The mean age of patients was 56 (±17) years. Fifty-seven percent were female. The IBD group was youngest (P < 0.001). IBD had significantly lower PROMIS scores on pairwise comparison; anorectal had the highest scores. Controlling for age and sex, the IBD group had 4.1× odds of poor physical health (95% confidence interval 2.46-6.76) and 2.9× odds of poor mental health (95% confidence interval 1.66-5.00).

Conclusions

Patients with IBD, specifically Crohn disease, have worse physical and mental health on presentation to a colorectal surgeon compared to patients presenting with other colorectal diagnoses. These patients considering surgery might benefit from added support during the perioperative period.

Update on colon cancer screening: recent advances and observations in colorectal cancer screening

There have been many recent advances and observations regarding colorectal cancer (CRC) screening. New CRC surveillance guidelines have been published to help endoscopists with the management of important clinical issues such as serrated polyps. There have been several important large studies examining the impact of endoscopic process measures such as bowel prep, withdrawal time, and adenoma detection rate on CRC screening. In addition, there have been technical advances in CT colonography including the development of exams that do not require a bowel preparation. Other new technology such as colon capsule endoscopy may aid endoscopists in the challenge of completing the evaluation of the colon in those patients with an incomplete colonoscopy. Finally, there have been large studies which examine the performance characteristics of the so-called non-invasive CRC screening tests such as fecal immunochemical test (FIT) and fecal DNA.

Smoking and the association of advanced colorectal neoplasia in an asymptomatic average risk population: analysis of exposure and anatomical location in men and women

BACKGROUND

Identifying risk factors for advanced colorectal adenomas may aid in colorectal cancer (CRC) screening, especially in light of the American College of Gastroenterology's recent guidelines, emphasizing cancer prevention through identification and removal of advanced adenomas. Smoking is an important risk factor for advanced adenomas but there is little data regarding levels of exposure for genders.

METHODS

The aim of this study was to use an existing database to examine the genders separately with respect to exposure level and anatomic location of advanced adenomas. Our database was designed to study smoking in an asymptomatic, screening population. Data included demographics, family history of CRC, smoking exposure (pack-years and years smoked), alcohol, diabetes, medications, exercise and dietary history. We excluded patients with a first degree relative with CRC.

RESULTS

Compared to non-smokers, female smokers had an increased risk for advanced adenomas with an exposure of 10-30 pack-years (adjusted odds ratio [AOR] = 4.11; 95% confidence interval [CI], 1.88-9.01) as well as for ≥30 pack-years (AOR = 2.54; 95% CI, 1.08-5.96) while men had an increased risk with smoking ≥30 pack-years (AOR = 3.10; 95% CI, 1.71-5.65). An increased association with smoking was observed for proximal advanced adenomas (AOR = 4.06; 95% CI, 1.62-10.19) and large hyperplastic polyps in women.

CONCLUSIONS

Women smokers had an increased risk for advanced adenomas at a lower exposure level and had a greater risk for proximal lesions. These findings may have an impact on CRC screening for women.

Rotavirus infection of murine small intestine causes colonic secretion via age restricted galanin-1 receptor expression

BACKGROUND & AIMS

Mechanisms for age restriction of rotavirus diarrhea are unclear. Because rotavirus primarily infects small intestine, colonic contribution has not been widely studied. Recent data suggest that colonic secretion postbacterial infection is mediated by galanin-1 receptors (Gal1-R). We evaluated age-dependent expression of Gal1-R in Rhesus rotavirus (RRV)-infected mice and its contribution to fluid secretion.

METHODS

Twenty-four hours after infection of C57BL/6J mice (wild type or Gal1-R knockout) with RRV or vehicle, closed small intestinal and colon loops were constructed. Net fluid content of the loops was calculated (milligrams/centimeters) at 2 hours post-treatment with galanin, galanin antibody, or lidocaine. Gal1-R expression was quantified by automated chromogen analysis.

RESULTS

Viral antigen was detected in small intestinal epithelial cells but not in colon. Developmental Gal1-R was widely expressed in the small intestine but minimally in the colon. Postinfection, markedly increased Gal1-R was seen in the colon but not after day 25. Galanin caused a significantly higher increase in the net fluid content of infected colon than small intestine. Treatment with lidocaine reduced net fluid secretion in the small intestine and the colon. Mean diarrheal scores were significantly reduced in Gal1-R knockout mice compared with wild type (1.19 +/- 0.31, n = 22 vs 3.36 +/- 0.50, n = 35, P = .0001).

CONCLUSIONS

These data show that RRV infection of the small intestine increases colonic secretion through Gal1-R and provide a promising start toward understanding the age restriction of rotavirus diarrhea.

Body mass index: a marker for significant colorectal neoplasia in a screening population

BACKGROUND AND AIMS

Although some studies suggest a positive association between increasing body mass index (BMI) and risk for colorectal neoplasia, the impact on screening has not been examined. We performed a cross-sectional study to examine the association of BMI and colorectal neoplasia in a screening population.

METHODS

Data collected for 2493 patients presenting for screening colonoscopy included known risk factors for colorectal neoplasia, demographic information, and lifestyle factors. Our outcome was the endoscopic detection of significant colorectal neoplasia which included adenocarcinoma, high-grade dysplasia, villous tissue, adenomas 1 cm or greater and multiple (>2) adenomas of any size.

RESULTS

Overall, we observed an increased risk and prevalence for significant colorectal neoplasia in women as BMI increased (P value for trend <0.002). This relationship was the strongest for the women with a BMI > or =40 (odds ratios=4.26; 95% confidence intervals=2.00-9.11). There was no such relationship in our male population.

CONCLUSIONS

Increasing BMI, in our population, was associated with an increase risk for colorectal neoplasia in female patients. This study reinforces the importance of screening colonoscopy especially in obese women.

Prevalence and risk of colorectal neoplasia in consumers of alcohol in a screening population

BACKGROUND AND AIMS

Although studies suggest a positive association between alcohol consumption and risk for colorectal neoplasia, the impact on screening has not been fully examined. It is also unclear whether all types of alcohol are associated with an increased risk. We performed a cross-sectional study to examine the impact of regular alcohol consumption on the detection of significant colorectal neoplasia in a screening population.

METHODS

Data collected for 2,291 patients presenting for screening colonoscopy: known risk factors for colorectal neoplasia and alcohol drinking pattern. Our outcome was the endoscopic detection of significant colorectal neoplasia, which included adenocarcinoma, high-grade dysplasia, villous tissue, adenomas 1 cm or greater and multiple (>2) adenomas of any size.

RESULTS

When compared to abstainers, we found an increased risk for significant neoplasia in those patients who consumed more than eight drinks of spirits alcohol (26.3%; OR = 2.53; 95% CI = 1.10-4.28; p < 0.01) and those who drank more than eight servings of beer per week (21.7%; OR = 2.43; 95% CI = 1.11-5.32; p= 0.02). Consuming one to eight glasses of wine per week was associated with a decreased risk for significant neoplasia (OR = 0.55; 95% CI = 0.34-0.87; p < 0.01).

CONCLUSIONS

While there was a more than twofold increased risk of significant colorectal neoplasia in people who drink spirits and beer, people who drank wine had a lower risk. In our sample, people who drank more than eight servings of beer or spirits per week had at least a one in five chance of having significant colorectal neoplasia detected by screening colonoscopy.

The cytokine osteopontin modulates the severity of rotavirus diarrhea

Osteopontin (OPN) is a sialated phosphoprotein found in tissues and secreted into body fluids. It is an integrin ligand with pleiotropic functions as an extracellular matrix protein in mineralized tissues and a cytokine that is active in cell signaling (A. B. Tuck, C. Hota, S. M. Wilson, and A. F. Chambers, Oncogene 22:1198-1205, 2003). To determine whether OPN may be important in mucosal defense against viral pathogens, we evaluated the OPN response to rotavirus infection and the extent of diarrhea manifested by infected opn null mutant (opn-/-) mice. Reverse transcription-PCR, Northern and Western blots, and immunohistochemical studies of the HT-29 intestinal epithelial cell line and murine intestine were used to evaluate OPN mRNA and product. Intestinal closed loops and diarrheal observations determined disease severity and duration. OPN mRNA levels increased after infection of HT-29 cells, peaking in 4 to 6 h. Infected cultures contained 925 microg of OPN/ml, while for controls the levels were below detection (50 microg/ml). Infection increased OPN mRNA levels in intestinal tissue between 2 and 24 h postinoculation and increased OPN protein in intestinal fluid. The cellular localization of OPN was supranuclear and apical, and responding cells were diffusely distributed on the villus surface. Three days after infection, closed intestinal loops from opn-/- mice contained more fluid than loops from controls, although secretion levels at the onset of illness were similar. Null mutant mice experienced more intense and prolonged diarrhea than controls. Rotavirus infection of intestinal epithelial cells and murine intestine caused marked increases in OPN mRNA levels and secreted OPN protein. OPN-deficient mice suffered prolonged disease.

VP4 differentially regulates TRAF2 signaling, disengaging JNK activation while directing NF-kappa B to effect rotavirus-specific cellular responses

Rotaviruses rapidly activate NF-kappaB and induce the secretion of selected chemokines after infection. The ability of rotavirus particles lacking genomic RNA to activate NF-kappaB suggested that rotavirus proteins direct cell signaling responses. We identified conserved TNFR-associated factor (TRAF) binding motifs within the rotavirus capsid protein VP4 and its N-terminal VP8* cleavage product. TRAFs (-1, -2, and -3) are bound by the rhesus rotavirus VP8* protein through three discrete TRAF binding domains. Expression of VP4 or VP8* from rhesus or human rotaviruses induced a 5-7-fold increase in NF-kappaB activity and synergistically enhanced TRAF2-mediated NF-kappaB activation. Mutagenesis of VP8* TRAF binding motifs abolished VP8* binding to TRAFs and the ability of the protein to activate NF-kappaB. Expression of pathway-specific dominant negative (DN) inhibitors DN-TRAF2 or DN-NF-kappaB-inducing kinase also abolished VP8*-, VP4-, or rotavirus-mediated NF-kappaB activation. These findings demonstrate that rotavirus primarily activates NF-kappaB through a TRAF2-NF-kappaB-inducing kinase signaling pathway and that VP4 and VP8* proteins direct pathway activation through interactions with cellular TRAFs. In contrast, transcriptional responses from AP-1 reporters were inhibited 5-fold by VP8* and were not activated by rotavirus infection, suggesting the differential regulation of TRAF2 signaling responses by VP8*. VP8* blocked JNK activation directed by TRAF2 or TRAF5 but had no effect on JNK activation directed by TRAF6 or MEKK1. This establishes that fully cytoplasmic rotaviruses selectively engage signaling pathways, which regulate cellular transcriptional responses. These findings also demonstrate that TRAF2 interactions can disengage JNK signaling from NF-kappaB activation and thereby provide a new means for TRAF2 interactions to determine pathway-specific responses.

Rotavirus alters paracellular permeability and energy metabolism in Caco-2 cells

Rotaviruses infect epithelial cells of the small intestine, but the pathophysiology of the resulting severe diarrhea is incompletely understood. Histological damage to intestinal epithelium is not a consistent feature, and in vitro studies showed that intestinal cells did not undergo rapid death and lysis during viral replication. We show that rotavirus infection of Caco-2 cells caused disruption of tight junctions and loss of transepithelial resistance (TER) in the absence of cell death. TER declined from 300 to 22 Omega. cm(2) between 8 and 24 h after infection and was accompanied by increased transepithelial permeability to macromolecules of 478 and 4,000 Da. Distribution of tight junction proteins claudin-1, occludin, and ZO-1 was significantly altered during infection. Claudin-1 redistribution was notably apparent at the onset of the decline in TER. Infection was associated with increased production of lactate, decreased mitochondrial oxygen consumption, and reduced cellular ATP (60% of control at 24 h after infection), conditions known to reduce the integrity of epithelial tight junctions. In conclusion, these data show that rotavirus infection of Caco-2 intestinal cells altered tight junction structure and function, which may be a response to metabolic dysfunction.

Viral infections of the gastrointestinal tract

Viral gastroenteritis is a major public health problem worldwide, and the number of identified pathogens continuously increases. Investigators have made considerable progress toward understanding both the epidemiology and the mechanisms of virus-cell interactions, host responses, and pathogenesis. A vaccine for the most important pathogen, rotavirus, has been approved by the US Food and Drug Administration, but possible complications have temporarily curbed the use of this vaccine.

Growth patterns and nutritional factors associated with increased head circumference at 18 months in normally developing, low-birth-weight infants

OBJECTIVE

To identify patterns of growth, nutrition practices, and feeding behaviors associated with normal Denver II developmental screening results at 18 months of age.

DESIGN

A retrospective review of hospital medical charts was conducted to collect discharge diagnosis and dietary data. Developmental clinic charts were reviewed to collect growth and diet data, Denver II results, and medical data from 4-, 9-, and 18-month visits.

SUBJECTS/SETTING

Twenty-eight children were identified from a review of developmental clinic records in a midwestern children's hospital. Criteria were single or twin birth, birth weight of 2,000 g or less, follow up at the hospital developmental clinic, and completion of 3 screening visits.

STATISTICAL ANALYSES PERFORMED

National standards were used to calculate z scores. Patterns of growth were analyzed using analysis of variance. Stepwise forward linear regression analysis was done to construct a model predicting head circumference at 18 months of age.

RESULTS

Significant catch-up growth (P = .0006) occurred as length z score increased from -0.87 at 4 months of age to -0.45 at 18 months. A regression model predicting head circumference at age 18 months was developed that included nutrition and growth variables such as head circumference at 9 months, type of parenteral amino acids administered in the hospital, z score of weight at 4 months' adjusted age, and time of first enteral feeding.

APPLICATIONS

Interventions designed to support breast-feeding in the hospital and at home are indicated as is increased emphasis on monitoring growth. Delays in growth need to be treated aggressively; for example, nutrition interventions should begin by the age of 4 months if weight gain is not appropriate.

The epithelial cell response to rotavirus infection

Rotavirus is the most important worldwide cause of severe gastroenteritis in infants and young children. Intestinal epithelial cells are the principal targets of rotavirus infection, but the response of enterocytes to rotavirus infection is largely unknown. We determined that rotavirus infection of HT-29 intestinal epithelial cells results in prompt activation of NF-kappaB (<2 h), STAT1, and ISG F3 (3 h). Genetically inactivated rotavirus and virus-like particles assembled from baculovirus-expressed viral proteins also activated NF-kappaB. Rotavirus infection of HT-29 cells induced mRNA for several C-C and C-X-C chemokines as well as IFNs and GM-CSF. Mice infected with simian rotavirus or murine rotavirus responded similarly with the enhanced expression of a profile of C-C and C-X-C chemokines. The rotavirus-stimulated increase in chemokine mRNA was undiminished in mice lacking mast cells or lymphocytes. Rotavirus induced chemokines only in mice <15 days of age despite documented infection in older mice. Macrophage inflammatory protein-1beta and IFN-stimulated protein 10 mRNA responses occurred, but were reduced in p50-/- mice. Macrophage inflammatory protein-1beta expression during rotavirus infection localized to the intestinal epithelial cell in murine intestine. These results show that the intestinal epithelial cell is an active component of the host response to rotavirus infection.

The Epithelial Cell Response to Rotavirus Infection

Rotavirus is the most important worldwide cause of severe gastroenteritis in infants and young children. Intestinal epithelial cells are the principal targets of rotavirus infection, but the response of enterocytes to rotavirus infection is largely unknown. We determined that rotavirus infection of HT-29 intestinal epithelial cells results in prompt activation of NF-κB (&lt;2 h), STAT1, and ISG F3 (3 h). Genetically inactivated rotavirus and virus-like particles assembled from baculovirus-expressed viral proteins also activated NF-κB. Rotavirus infection of HT-29 cells induced mRNA for several C-C and C-X-C chemokines as well as IFNs and GM-CSF. Mice infected with simian rotavirus or murine rotavirus responded similarly with the enhanced expression of a profile of C-C and C-X-C chemokines. The rotavirus-stimulated increase in chemokine mRNA was undiminished in mice lacking mast cells or lymphocytes. Rotavirus induced chemokines only in mice &lt;15 days of age despite documented infection in older mice. Macrophage inflammatory protein-1β and IFN-stimulated protein 10 mRNA responses occurred, but were reduced in p50−/− mice. Macrophage inflammatory protein-1β expression during rotavirus infection localized to the intestinal epithelial cell in murine intestine. These results show that the intestinal epithelial cell is an active component of the host response to rotavirus infection.

Viral infections of the gastrointestinal tract

Viral gastroenteritis is a major worldwide public health problem. The number of identified pathogens continues to increase, and characterization of the viral structures and functions must be inexorably pursued. Investigators have made considerable progress toward understanding the mechanisms of virus-cell interactions, host responses, and pathogenesis, but the application of this knowledge to improve disease treatment and prevention awaits further key discoveries. Despite deficiencies in knowledge of many aspects of these important issues, a vaccine for the most important pathogen, rotavirus, has been submitted to the US Food and Drug Administration for approval.

Detection of serum antibodies to Helicobacter pylori by an immunochromatographic method

OBJECTIVES

FlexsureHP is a bi-directional immunochromatographic device for detection of IgG antibodies to Helicobacter pylori in human serum. This test, requiring only three steps and a 4-min incubation, can be used as an office-based diagnostic test. The goal of this study was to compare the sensitivity and specificity of the FlexsureHP, when performed by a clinician, with the established ELISA in the evaluation of clinical samples in an office setting.

RESULTS

The sensitivity and specificity of the FlexsureHP, compared with the biopsy, is 92.4% and 83.0%, respectively, with a positive predictive value of 88.4%. This was not significantly different from the results obtained when the ELISA was compared with biopsy data.

CONCLUSION

The immunochromatographic device, FlexsureHP, is a rapid, highly sensitive, and moderately specific office-based diagnostic test for H. pylori infection.

Replication as a determinant of the intestinal response to rotavirus

Mucosal antibody induction by otherwise identical replication-competent and replication-incompetent rhesus monkey rotaviruses was compared. Although psoralen-inactivated virus induced diarrhea, the magnitude of the intestinal antibody response was severely attenuated compared with that of replicating rotavirus, as determined by assay of mucosal antibody-secreting cells. Rotavirus that was neutralized by monoclonal antibodies (anti-VP4 and -VP7) prior to inoculation was similarly ineffective at induction of specific antibodies in intestinal secretions. In contrast to genetically inactivated virus, antibody-neutralized virus did not induce diarrhea. In this murine model, viral replication is an important determinant of antibody induction. The diarrhea response is blocked by neutralizing antibodies, but the mechanism of action is not exclusively the inhibition of viral replication.

Rotavirus stimulates IL-8 secretion from cultured epithelial cells

Rotavirus is the most important cause of severe gastroenteritis in children worldwide. We have investigated cytokine responses to rotavirus infection of cultured intestinal epithelial cells. Interleukin 8 (IL-8) is a chemotactic and cell-activating cytokine that is synthesized by epithelial cells and induced in response to bacterial enteric pathogens. Rotavirus inoculation increased IL-8 mRNA levels in cultured intestinal epithelial cells within 2 hr of infection. IL-8 secretion increased 10(2)- to 10(3)-fold by 8 hr postinfection. Secretion of TNF alpha or IL-1 beta, cytokines which themselves increase IL-8 secretion, was not induced by rotavirus, nor was that of TNF alpha, IFN alpha, IFN gamma, or IL-6. Neutralizing antibodies to TNF alpha or IL-1 alpha/beta did not affect the IL-8 response. Secretion of IL-8 was dependent on an intact viral capsid, as single-shell particles were inert. Neutralizing monoclonal antibodies (vp7-specific) that do not block cell attachment did block rotavirus stimulation of IL-8 secretion, indicating that attachment to the cell surface is not a sufficient stimulus to induce IL-8. Genetically inactivated rotavirus was also effective for IL-8 induction, indicating that viral replication was not required. These data suggest that epithelial cytokine IL-8 may be an important mediator of the host response to viral gastroenteritis pathogens such as rotavirus.

Rotavirus diarrhea is caused by nonreplicating viral particles

Rotaviruses infect the villous epithelium of the small intestine and cause severe diarrhea in young children. The mechanism by which rotavirus causes diarrhea has not been elucidated. It has been hypothesized that rotavirus replication in the intestinal epithelium causes a loss of viable absorptive cells, leading to an imbalance of intestinal secretion and absorption. Cell destruction has generally been thought to result from rotavirus transcription and replication. However, the widely used heterologous murine model of rotavirus infection demonstrates minimal viral replication and histological changes limited to epithelial vacuolation on the distal villus despite the simultaneous occurrence of voluminous liquid diarrhea. We have genetically inactivated rotaviruses to test the importance of viral replication in the pathogenesis of rotavirus-induced diarrhea. We present direct evidence that transcription- and replication-defective rotaviruses cause diarrhea in an animal model. These findings suggest that rotavirus attachment or entry into cells is sufficient for the induction of diarrhea. The mechanism of rotavirus-induced diarrhea is therefore consistent with a viral toxin-like effect exerted during virus-cell contact.

Effects of rotavirus on epithelial transport in rabbit small intestine

The present study investigated changes in small intestinal epithelial transport in rabbits infected with rotavirus. The crypt depth-villus height ratio was increased in infected ileal tissue as a result of a significant increase in crypt depth and patchy shortening of the villi. Similar villus damage was seen in the jejunum. Despite these histological changes, basal fluid absorption by both the ileum and jejunum of infected animals was unaltered. Values for basal short-circuit current and resistance were similar; however, the increase in short-circuit current evoked by prostaglandin E2 was significantly smaller in rotavirus-infected tissues than in controls. The apparent Vmax for electrogenic glucose and alanine uptake by the jejunum was significantly increased following inoculation with rotavirus. Reduced responsiveness to the secretory effect of prostaglandin E2 and increased nutrient uptake may limit diarrhea that would otherwise be expected to occur as a result of the changes in mucosal architecture. This has important implications on the clinical treatment of rotavirus diarrhea, suggesting that oral rehydration therapy, which depends on the active transport of nutrients, may provide a more effective treatment than the use of cyclooxygenase inhibitors.

Infectious diarrhoea. Viruses

Increased knowledge has been gained into the aetiology and pathogenesis of viral gastroenteritis during the past two decades. There are now thought to be four major subclassifications of gastroenteritis-causing viruses; these include rotavirus, enteric adenovirus, calicivirus, including Norwalk and Norwalk-like viruses, and astrovirus. The association of these agents with gastroenteritis has been made by their electron microscopic detection in stool and intestinal biopsy specimens from affected patients, the inability to detect the viruses after recovery from disease, and the subsequent development of immunoglobulin responses after infection; in some instances disease transmission was achieved in human volunteers. The association of these viral agents with gastroenteritis has facilitated the study of classification, epidemiology, immunity, diagnostic tests, methods of treatment and, most importantly, disease prevention strategies such as vaccine development for rotavirus. This chapter highlights the major features of these agents, with special attention being given to the pertinent molecular biology as well as current and future prospects for vaccination. Enteric viral infections of the gastrointestinal tract in patients with AIDS are also discussed.

Persistence of intestinal antibody response to heterologous rotavirus infection in a murine model beyond 1 year

We used an ELISPOT (enzyme-linked immunosorbent spot) assay to quantitate the long-term rotavirus-specific intestinal antibody response in a murine model. The frequency of murine intestinal antibody-secreting cells (ASCs) was followed for a period of 1 year after a single dose of rhesus rotavirus (10(6) PFU) was administered at 10 days of age. Some animals were boosted at that time with a second dose. One year after infection, virus-specific ASCs declined from acute-phase levels, but they were still present at significant levels (1.32 x 10(4) virus-specific ASCs per 10(6) intestinal mononuclear cells; approximately 17% of the previously reported response at 1 month after infection). A booster dose 1 year after the primary infection produced a 100% increase in virus-specific ASCs but did not restore the response to that of the primary infection.

Psoralen preparation of antigenically intact noninfectious rotavirus particles

The use of the synthetic psoralen 4'-aminomethyl-4,5',8-trimethylpsoralen hydrochloride (AMT) is described for the inactivation of infectious rotavirus, a member of the viral family Reoviradae with a double-stranded RNA genome. This method not only provides complete inactivation of the virus but leaves antigenically intact particles. The lack of viral replication following inactivation was determined with an immunohistochemical focus assay. The antigenic authenticity of the particles was determined by monoclonal antibody ELISA and a viral hemagglutination assay.

Kayaking as a risk factor for leptospirosis

Leptospirosis is a common zoonosis present throughout Missouri. Previously regarded as an occupational illness of farmers and sewer workers, it is now primarily acquired from exposure to water polluted with the bacteria Leptospira. We present a case report of leptospirosis acquired through kayaking and review both the disease and the risk factor associated with kayaking.

Recombinant baculovirus-expressed rotavirus protein (VP4) in an ELISPOT assay of antibody secretion

Studies on the protein specificity of the intestinal antibody response to rotavirus infection have been hampered by lack of antigenically conserved isolated proteins to serve as antigens in immunochemical assays. In this report, the use of an antigenically conserved baculovirus-expressed rotavirus protein (VP4) as a capture antigen in the ELISPOT assay is described. Anti-VP4 antibody-secreting hybridoma cells are used as a test population to show that expressed VP4 as the capture antigen detects numbers of antibody secreting cells comparable to intact rotavirus particles. Hybridoma cells specific for other rotavirus proteins are used to ensure the specificity of the expressed VP4 in the assay. The flexibility and ease of use of a recombinant expressed protein product as a capture antigen in this assay dramatically enhances the ability to quantitate intestinal antibody responses to specific viral proteins.

Murine intestinal antibody response to heterologous rotavirus infection

Rotavirus is the most important worldwide cause of severe gastroenteritis. Extensive efforts have been devoted to the design of a vaccine that will prevent disease, but development of a more effective vaccine strategy may require progress in the understanding of the mucosal immune response to replicating viral antigens. In this article, we report the characterization of the intestinal antibody response of a murine model to heterologous infection with the rhesus rotavirus vaccine strain. We have adapted the enzyme-linked immunospot assay to measure this response without the difficulties associated with measurement of antibodies in intestinal contents or the artifacts associated with culturing of lymphocytes. The predominant response in terms of antibody-secreting cells (ASC) is seen in the small intestine lamina propria, which can be measured within 4 days of infection, peaks 3 weeks after infection, and remains near that level for longer than 8 weeks. The magnitude of the immunoglobulin A (IgA) cell response is approximately 10 times greater than the intestinal IgG cell response, and IgM cells are rare. Virus-specific ASC constitute approximately 50% of all ASC in the gut at the peak of the virus-specific response. This response is considerably greater than responses to nonreplicating mucosal antigens measured by similar techniques. Enteral infection engenders minimal virus-specific ASC response in the spleen. Rhesus rotavirus-specific enzyme-linked immunosorbent assay and neutralization assays of serum and intestinal contents did not correlate with virus-specific ASC response.

VP4-specific intestinal antibody response to rotavirus in a murine model of heterotypic infection

We have adapted a murine model of heterotypic rotavirus infection for the purpose of evaluating the intestinal antibody response to an infection that mimics human vaccination. Neonatal mice were infected with the rhesus rotavirus (RRV). The enzyme-linked immunospot assay was used in order to avoid common artifacts in the quantitation of intestinal immune responses inherent in measurements of luminal or serum immunoglobulins and to obtain easily quantifiable data in a flexible and convenient format. Functionally active lymphocytes were harvested from the spleen, small intestinal lamina propria, Peyer's patches, and mesenteric lymph nodes and processed into single-cell suspensions. Antibody-secreting cells (ASC) were quantitated from 5 to 50 days after infection for total, RRV-specific, baculovirus-expressed VP4-specific, and single-shell RRV-specific ASC secreting either immunoglobulin G (IgG), IgM, or IgA. The response to VP4 constituted less than 1.5% of the total virus-specific response, which was located almost exclusively in the gut and was 90% IgA. Intestinal ASC were directed overwhelmingly toward proteins incorporated in the single-shell particle, predominantly VP2 and VP6. We conclude that the antibody response to VP4, thought to be the site of the important neutralization sites conserved among several rotavirus serotypes, is an extremely small portion of the overall antibody response in the intestinal tract.

Passive protection against rotavirus-induced diarrhea by monoclonal antibodies to the heterotypic neutralization domain of VP7 and the VP8 fragment of VP4

A murine model was used to determine whether neutralizing monoclonal antibodies (MAbs) with heterotypic specificity directed to VP7 (MAb 57-8) or to the VP8 fragment of VP4 (MAb M14) passively protect mice against challenge with various strains of rotavirus. (The gene 4 product, an outer capsid protein, has traditionally been called VP3. It has been proposed, however, that the rotavirus gene 4 product be named VP4. The gene 3 product, a core protein, has been identified recently and named VP3 [M. Liu, P. A. Offit, and M. K. Estes, Virology 163:28-32, 1988]). Suckling mice orally inoculated with MAb 57-8 did not develop diarrhea when challenged with virulent serotype 3, 4, or 6 rotaviruses, while those inoculated with MAb M14 were passively protected from challenge with serotype 3 or 6 rotaviruses, as predicted by in vitro neutralization tests. These MAbs, however, did not protect mice from infection when the mice were challenged with rotaviruses of other serotypes. We conclude that specific neutralization epitopes on each surface protein are capable of mediating protection against one or several rotavirus serotypes.

Serotypic analysis of VP3 and VP7 neutralization escape mutants of rhesus rotavirus

Neutralization escape mutants of simian rotaviruses (rhesus rotavirus and SA11) were tested in hemagglutination inhibition and neutralization assays against hyperimmune and infection sera to determine if mutation in an immunodominant epitope could enable neutralization escape. An SA11 mutant with a new glycosylation site at amino acid 211 of VP7 was shown to escape neutralization by hyperimmune but not infection sera.

Characterization of homotypic and heterotypic VP7 neutralization sites of rhesus rotavirus

The gene 9 nucleotide sequence was determined for rhesus rotavirus and each of 14 viral variants selected for their resistance to neutralizing monoclonal antibodies. Each variant contains a single gene 9, VP7, mutation which permits viral growth in the presence of the antibody. Variant mutations were identified in two distinct neutralization regions. Region A was identified by monoclonal antibodies that are involved in both serotype-specific and serotype cross-reactive neutralization. Region C was identified by serotype-specific neutralizing monoclonal antibodies. Heterotypic neutralizing monoclonal antibody 57-8 selected variants with a mutation at amino acid 94 in the A region, the same amino acid location selected by serotype-specific monoclonal antibodies. Monoclonal antibody 3 selected a VP7 mutation at amino acid 99 resulting in additional N-linked glycosylation of the VP7 protein. Despite the added VP7 glycosylation, variant v3 was not broadly resistant to additional VP7-specific neutralizing monoclonal antibodies.

Functional and topographical analyses of epitopes on the hemagglutinin (VP4) of the simian rotavirus SA11

An immunochemical analysis of the hemagglutinin (VP4) of the simian rotavirus SA11 was performed to better understand the structure and function of this molecule. Following immunization of mice with double-shelled virus particles and VP4-enriched fractions from CsCl gradients, a battery of anti-SA11 hybridomas was generated. A total of 13 clones secreting high levels of anti-VP4 monoclonal antibody (MAb) was characterized and compared with two cross-reactive anti-VP4 MAbs generated against heterologous rhesus (RRV) and porcine (OSU) rotavirus strains. These cross-reactive MAbs effectively neutralized SA11 infectivity in vitro. The epitopes recognized by these 15 MAbs were grouped into six antigenic sites on the SA11 hemagglutinin. These sites were identified following analysis of the MAbs by using a simple competitive binding enzyme-linked immunosorbent assay (ELISA) and biological assays. Three of the antigenic sites were involved in neutralization of virus infectivity in vitro. All the MAbs with neutralization activity and two nonneutralizing MAbs were able to inhibit viral hemagglutination of human erythrocytes. Competitive binding ELISA data showed a positive cooperative binding effect with some pairs of the anti-VP4 MAbs, apparently due to a conformational change induced by the binding of the first MAb. Some of the MAbs also bound better to trypsin-treated virus than to non-trypsin-treated virus. A topographic map for VP4 is proposed on the basis of the observed properties of each antigenic site.

Infectious rotavirus enters cells by direct cell membrane penetration, not by endocytosis

Rotaviruses are icosahedral viruses with a segmented, double-stranded RNA genome. They are the major cause of severe infantile infectious diarrhea. Rotavirus growth in tissue culture is markedly enhanced by pretreatment of virus with trypsin. Trypsin activation is associated with cleavage of the viral hemagglutinin (viral protein 3 [VP3]; 88 kilodaltons) into two fragments (60 and 28 kilodaltons). The mechanism by which proteolytic cleavage leads to enhanced growth is unknown. Cleavage of VP3 does not alter viral binding to cell monolayers. In previous electron microscopic studies of infected cell cultures, it has been demonstrated that rotavirus particles enter cells by both endocytosis and direct cell membrane penetration. To determine whether trypsin treatment affected rotavirus internalization, we studied the kinetics of entry of infectious rhesus rotavirus (RRV) into MA104 cells. Trypsin-activated RRV was internalized with a half-time of 3 to 5 min, while nonactivated virus disappeared from the cell surface with a half-time of 30 to 50 min. In contrast to trypsin-activated RRV, loss of nonactivated RRV from the cell surface did not result in the appearance of infection, as measured by plaque formation. Endocytosis inhibitors (sodium azide, dinitrophenol) and lysosomotropic agents (ammonium chloride, chloroquine) had a limited effect on the entry of infectious virus into cells. Purified trypsin-activated RRV added to cell monolayers at pH 7.4 medicated 51Cr, [14C]choline, and [3H]inositol released from prelabeled MA104 cells. This release could be specifically blocked by neutralizing antibodies to VP3. These results suggest that MA104 cell infection follows the rapid entry of trypsin-activated RRV by direct cell membrane penetration. Cell membrane penetration of infectious RRV is initiated by trypsin cleavage of VP3. Neutralizing antibodies can inhibit this direct membrane penetration.

The rhesus rotavirus gene encoding protein VP3: location of amino acids involved in homologous and heterologous rotavirus neutralization and identification of a putative fusion region

The complete gene 4 nucleotide sequence was determined for rhesus rotavirus and each of 11 viral variants selected by neutralizing monoclonal antibodies. Gene 4 is 2362 bases in length and encodes a protein, VP3, of 776 amino acids with a calculated Mr of 86,500. A conserved trypsin cleavage site, located at amino acid 247, divides VP3 into VP8 and VP5. Neutralizing monoclonal antibodies directed at VP3 were used to select variants that escaped neutralization. Each variant contains a single gene 4 mutation that permits viral growth in the presence of the antibody. Variant mutations were identified in six distinct neutralization regions in VP8 and VP5. Five of the six neutralization regions were found in VP8. The VP8 regions were primarily associated with strain-specific or limited heterotypic rotavirus neutralization. One region was identified in VP5 by three monoclonal antibodies that neutralize a broad range of rotavirus serotypes. The VP5 neutralization region is largely hydrophobic and is similar to putative fusion sequences of Sindbis and Semliki Forest viruses.

Epitope-specific immune responses to rotavirus vaccination

Rotavirus gastroenteritis is a leading cause of infant mortality in developing countries and an important cause of morbidity in children under 2 yr of age in the United States. Vaccine programs have evaluated animal rotavirus strains that are attenuated in humans but antigenically similar to some human strains. Whether a single vaccine strain can elicit protective immunity in humans to rotaviruses of the same or different serotypes is an important question in determining vaccine efficacy. We used characterized serotype-specific monoclonal antibodies directed at VP7 in a competitive solid-phase immunoassay to measure epitope-specific immune responses to serotypes 1, 2, and 3 in sera of children who received a candidate serotype-3 rotavirus vaccine. Antibodies to serotype 3 were detected in 72% of sera samples, and to serotype 1 and 2 in only 11% each. Also, a VP3-specific monoclonal antibody which neutralizes three serotypically distinct strains of rotavirus was used to detect the presence of similar antibodies in 56% of the test sera. This finding suggests a mechanism of heterotypic immunity.

Examination of sexually abused adolescents

The care of the sexually assaulted adolescent demands an integrated, sensitive approach to psychologic and medical needs, along with careful follow-up. This care is best provided by knowledgeable and supportive individuals. This discussion has reviewed definitions of sexual assault terms, potential psychologic reactions, physical evaluation of these individuals, and therapy considerations.

Antigenic mapping of the surface proteins of rhesus rotavirus

Monoclonal antibodies have been produced and used to map the functional topography of the surface proteins of rhesus rotavirus (RRV) that mediate viral neutralization. Ten monoclonal antibodies directed to VP7 were studied in neutralization assays and competitive binding studies. A large neutralization domain with several interrelated epitopes on VP7 was apparent. Twelve monoclonal antibodies directed to VP3 were used in similar studies and delineated at least 2 distinct neutralization domains on that protein. Neutralizing monoclonal antibodies directed at both VP3 and VP7 were used to isolate viral antigenic variants, which were than studied in neutralization and hemagglutination inhibition assays. The viral variant studies, while confirming the general conclusions obtained from the competitive binding studies, allowed the apparent distinction of two separate neutralization domains on VP7 and three on VP3. All VP7-specific monoclonal antibodies (mAb) mediated serotype-specific neutralization, but a VP3-specific mAb was identified that neutralized rotaviruses of three distinct serotypes. No alteration of viral virulence was apparent in studies of suckling mice orally inoculated with antigenic variant viruses selected with our panel of neutralizing VP3 or VP7-specific mAbs.