Binding affinity between coronavirus spike protein and human ACE2 receptor

Coronaviruses (CoVs) pose a major risk to global public health due to their ability to infect diverse animal species and potential for emergence in humans. The CoV spike protein mediates viral entry into the cell and plays a crucial role in determining the binding affinity to host cell receptors. With particular emphasis on α- and β-coronaviruses that infect humans and domestic animals, current research on CoV receptor use suggests that the exploitation of the angiotensin-converting enzyme 2 (ACE2) receptor poses a significant threat for viral emergence with pandemic potential. This review summarizes the approaches used to study binding interactions between CoV spike proteins and the human ACE2 (hACE2) receptor. Solid-phase enzyme immunoassays and cell binding assays allow qualitative assessment of binding but lack quantitative evaluation of affinity. Surface plasmon resonance, Bio-layer interferometry, and Microscale Thermophoresis on the other hand, provide accurate affinity measurement through equilibrium dissociation constants (KD). In silico modeling predicts affinity through binding structure modeling, protein-protein docking simulations, and binding energy calculations but reveals inconsistent results due to the lack of a standardized approach. Machine learning and deep learning models utilize simulated and experimental protein-protein interaction data to elucidate the critical residues associated with CoV binding affinity to hACE2. Further optimization and standardization of existing approaches for studying binding affinity could aid pandemic preparedness. Specifically, prioritizing surveillance of CoVs that can bind to human receptors stands to mitigate the risk of zoonotic spillover.

Effect of Tooth Bleach on Dentin Fatigue Resistance in Situ

BACKGROUND

Negative effects of bleaching on dentin have previously been reported in vitro.

OBJECTIVE

The purpose of this study was to determine the effect of carbamide peroxide bleaching on dentin fatigue resistance using a clinically relevant in situ model.

METHODS AND MATERIALS

Following research ethics board approval, 60 human teeth requiring extraction were collected. Sterilized human dentin specimens were cut (1.2x1.2x10 mm) and secured into customized bleaching trays to be used by study participants. Participants were randomly assigned to either bleach (10% carbamide peroxide, n=23) or control (gel without bleach, n=26) treatment groups. Treatment was applied to the bleaching trays and worn overnight by participants for 14 days. After treatment completion, dentin specimens were removed from the bleaching trays and subjected to fatigue testing (10 N, 3 mm/s, 2x105 cycles) while submerged in artificial saliva. Kaplan-Meier survival analysis was conducted to compare the number of cycles to failure during fatigue testing in both groups. A log rank test was run to determine if there were differences in the survival distribution between the two groups (α<0.05).

RESULTS

The median number of cycles to failure was 352 ± 202 and 760 ± 644 for the bleach and control groups, respectively. The survival distributions for the two groups were significantly different (p=0.020). Dentin fatigue resistance was significantly lower in the bleach group compared to the control.

CONCLUSIONS

Direct bleaching of human dentin using an at-home tray bleaching protocol in situ reduced dentin fatigue resistance. This has implications for tooth fracture risk and longevity.

A162 RARE PRESENTATION OF EXTRANODAL NK/T-CELL LYMPHOMA INVOLVING STOMACH AND EYE: CASE REPORT AND LITERATURE REVIEW

Background

Extranodal NK/T-cell lymphoma (ENKTL) is a rare and aggressive form of non-Hodgkin lymphoma. ENKTL are predominantly localized to nasal and upper aerodigestive sites, but extranasal involvement including gastrointestinal tract are rarely seen. Small and large intestines are primary sites of gastrointestinal ENKTL. Gastric involvements are exceedingly rare accounting for less than 5% of all gastrointestinal ENKTL.

Purpose

We present a literature review on gastrointestinal ENKTL and a case report of gastrointestinal bleed secondary to ENKTL involving stomach and left orbit.

Method

Case report and literature review.

Result(s)

33-year-old female was admitted to a tertiary hospital with 3-week history of epigastric pain and left periorbital swelling. Abdominal CT showed edema and thickening of gastric folds. Head CT showed grossly enlarged left lateral rectus muscle and periorbital soft tissue swelling suggestive of left orbital pseudotumor. Esophagogastroduodenoscopy revealed multifocal Forrest classification II-C ulcerations throughout her stomach and duodenum. Biopsies from stomach showed gastric mucosa with extensive infiltration by an atypical lymphoid cell population. Immunohistochemistry demonstrated high grade lymphoid cells with uniform expression of CD2, CD3, CD30, CD56, TIA1, perforin and granzyme B. EBV-encoded small RNA in-situ hybridization (EBER ISH) was strongly positive. Findings were consistent with gastric ENKTL. Left orbital biopsy revealed similar morphology and phenotypic features consistent with concurrent ENKTL involvement of her orbit. Patient was initiated on intravenous corticosteroids, but unfortunately developed hemorrhagic shock secondary to gastrointestinal bleeding from gastric ulcer and passed away.

Gastrointestinal ENKTL is a rare presentation of a rare disease. Gastric involvement is especially rare and described only in few case reports. Gastrointestinal ENKTL are often initially asymptomatic but can progress to abdominal pain, bleeding and even bowel perforation. Due its nonspecific clinical features and rarity, diagnosis can be difficult and requires careful examination by an experienced pathologist. This aggressive lymphoma is characterized by positive CD2, CD3, CD30, CD56, TIA, granzyme B, perforin and EBER ISH. Optimal treatment approach remains unclear due to lack of prospective clinical studies. Currently, treatment modalities used for other lymphomas including radiotherapy and non-anthracycline-based chemotherapy are used. Despite treatment, prognosis is grim with median overall survival period of 7-8 months.

Image

Conclusion(s)

We present a case of gastric and orbital ENKTL with gastric ulcer bleeding. Gastric ENKTL disease is a rare presentation of a rare disease. Due to non-specific clinical features, diagnosis is often difficult and relies on careful pathology examination by experienced pathologist. Prognosis is poor without optimal treatment approach due to rarity of disease and lack of validated data.

Please acknowledge all funding agencies by checking the applicable boxes below

None

Disclosure of Interest

None Declared

INFLAMMATORY BOWEL DISEASES

MECHANISMS AND TREATMENTS

A97 LARGE NON-PEDUNCULATED COLONIC POLYP (LNPCP) OUTCOMES REFERRED FOR ENDOSCOPIC RESECTION IN BRITISH COLUMBIA: A QUALITY ASSURANCE INITIATIVE

Background

Endoscopic resection techniques have become the primary treatment strategy for the vast majority of large (≥ 20mm) non-pedunculated colonic polyps (LNPCPs). Despite this, surgery is still commonly performed with evidence suggesting an increasing trend over time. There is limited Canadian data confirming the effectiveness and safety of an endoscopic management strategy for LNPCPs.

Purpose

To investigate clinical outcomes of patients referred for endoscopic management of a LNPCP.

Method

Retrospective single-centre analysis of patients referred to a single endoscopist for the management of LNPCPs within a tertiary referral practice. LNPCPs were further subdivided into non-complicated (NC-LNPCP) or complicated (C-LNPCP) defined as those involving the ileocecal valve, appendiceal orifice, circumferential or previously attempted. Performance outcomes were evaluated by the frequencies of technical success (removal of all polypoid tissue during index procedure) and need for colorectal surgery. Safety was evaluated by the frequencies of clinically significant intraprocedural bleeding (CSIPB), clinically significant post-endoscopic resection bleeding (CSPEB), intra-procedural perforation and delayed perforation. Recurrence (either endoscopic or histologic) was evaluated at first surveillance colonoscopy (SC1). Continuous variables were summarized using median (IQR). Categorical variables were summarized as frequencies (%). To test for association between categorical variables, the Pearson χ2 or the Fisher exact test were used, where appropriate. For continuous variables, the Mann-Whitney U test was used. A probability (p) value of <0.05 was considered statistically significant.

Result(s)

Between January 2021 to March 2022, 263 LNPCP were referred for endoscopic resection and 41 LNPCP were excluded (23 pedunculated, 14 optical evaluation suggestive of deeply invasive cancer, 4 other). 222 LNPCP (188 NC-LNPCP, 34 C-LNPCP) underwent endoscopic resection. Median size was 25mm (IQR 20-30mm) with the majority undergoing cold snare resection (115, 51.8%). Polyposis (Adenomatous or serrated) was present in 23 (12.6%) cases respectively. Technical success was 97.3%. Cancer was present in 5 (2%). Clinically significant bleeding (CSPEB) occurred in 2.7%, DMI IV in 1.8% and there were no delayed perforations. Recurrence occurred in 4 (3.5%) at SC1 and 11 (5%) required surgery due to technical failure, submucosal invasion on pathology and clinically significant bleeding.

Image

Conclusion(s)

Endoscopic resection as the primary treatment strategy for LNPCPs offers a safe and effective alternative to surgery in British Columbia.

Please acknowledge all funding agencies by checking the applicable boxes below

None

Disclosure of Interest

None Declared

Radiomics Can Distinguish Pediatric Supratentorial Embryonal Tumors, High-Grade Gliomas, and Ependymomas

BACKGROUND AND PURPOSE

Pediatric supratentorial tumors such as embryonal tumors, high-grade gliomas, and ependymomas are difficult to distinguish by histopathology and imaging because of overlapping features. We applied machine learning to uncover MR imaging-based radiomics phenotypes that can differentiate these tumor types.

MATERIALS AND METHODS

Our retrospective cohort of 231 patients from 7 participating institutions had 50 embryonal tumors, 127 high-grade gliomas, and 54 ependymomas. For each tumor volume, we extracted 900 Image Biomarker Standardization Initiative-based PyRadiomics features from T2-weighted and gadolinium-enhanced T1-weighted images. A reduced feature set was obtained by sparse regression analysis and was used as input for 6 candidate classifier models. Training and test sets were randomly allocated from the total cohort in a 75:25 ratio.

RESULTS

The final classifier model for embryonal tumor-versus-high-grade gliomas identified 23 features with an area under the curve of 0.98; the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 0.85, 0.91, 0.79, 0.94, and 0.89, respectively. The classifier for embryonal tumor-versus-ependymomas identified 4 features with an area under the curve of 0.82; the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 0.93, 0.69, 0.76, 0.90, and 0.81, respectively. The classifier for high-grade gliomas-versus-ependymomas identified 35 features with an area under the curve of 0.96; the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 0.82, 0.94, 0.82, 0.94, and 0.91, respectively.

CONCLUSIONS

In this multi-institutional study, we identified distinct radiomic phenotypes that distinguish pediatric supratentorial tumors, high-grade gliomas, and ependymomas with high accuracy. Incorporation of this technique in diagnostic algorithms can improve diagnosis, risk stratification, and treatment planning.

A59 A RARE PRESENTATION OF COLLAGENOUS GASTRODUODENITIS WITH 10 YEAR FOLLOW UP

Background

Collagenous gastritis(CG) is a rare form of gastritis defined histologically by the presence of &gt;10um of subepithelial surface collagen deposition. CG can further be categorized in childhood onset CG and adult onset CG. The prevalence of childhood CG is 2.1/100,000 in children aged younger than 18. Adult onset CG remains a rare entity. Here, we describe a rare presentation of collagenous gastroduodenitis in an adult patient and the interval progression over a 10 year period.

Aims

To increase awareness of a rare condition with limited data on available treatment modalities and clinical outcomes in adults.

Methods

Case Report

Results

A 35 year old female with no past medical history presented with worsening fatigue and increased shortness of breath with no overt gastrointestinal bleeding symptoms. There was no previous history of radiation exposure or family history of autoimmune disease. Laboratory investigations revealed iron deficiency anemia with a hemoglobin of 69 and a ferritin of 11. TTG serology and anti-parietal antibody was also negative. Esophagogastroduodenoscopy biopsies confirmed the diagnosis of collagenous gastritis localized to the gastric body with the presence of acute and chronic inflammatory changes. The patient was started on proton pump inhibitor therapy. In the interval period, the patient denies any new onset of gastrointestinal symptoms other than occasional heartburn. She remains iron deficient and requires regular iron infusions. Follow up endoscopy 10 years later now demonstrates diffuse mucosal abnormalities with a nodular contour involving the entire stomach and extending into the duodenal bulb. Biopsies showed features compatible with collagenous gastroduodenitis with active inflammation and pyloric metaplasia(Figure 1). There was atrophy of the stomach mucosa with no parietal cells identified and no endocrine hyperplasia. Immunostaining for Helicobacter pylori was negative. Flexible sigmoidoscopy was also performed revealing endoscopically normal colonic mucosa to the descending colon.

Conclusions

CG is a rare disease entity with unclear pathogenesis. Multiple case reports describe some association with autoimmune disease such as celiac disease. To date, no standard treatment has been identified for the management of CG. CG presents endoscopically with nodular changes, mucosal atrophy and collagen deposition. Over time, adult onset CG can progress to involve the entire stomach. Clinically, adult onset CG usually presents with a diarrhea predominant phenotype with associated collagenous colitis. Treatment modalities that have been trialed include PPI, corticosteroids, sucralfate, azathioprine,5-aminosalicylates, iron supplementation and hypoallergenic diets. Here we describe a rare presentation of collagenous gastroduodenitis and subsequent 10 year follow up in order to better understand this disease entity.

Funding Agencies

None

A155 ASEPTIC ABSCESS SYNDROME IN INFLAMMATORY BOWEL DISEASE: A CASE REPORT

Background

Aseptic abscess syndrome (AAS) is a rare extraintestinal manifestation of inflammatory bowel disease (IBD) and it is characterized by the formation of sterile collections of neutrophils in various organs. Misdiagnosis frequently leads to unnecessary surgical procedures and prolonged courses of antibiotics. There are only 61 reportable cases of AAS in the international literature and 2 cases in Canada. This case and the associated literature review highlight the diagnostic considerations, treatment options and disease course of this rare disease.

Aims

To describe a case of AAS in IBD.

Methods

Case report and review of the literature.

Results

A 24-year-old male with a history of ulcerative pancolitis (UC) initially presented with a 3-week history of malaise, abdominal pain, and fevers with a computed tomography (CT) scan showing multiple splenic abscesses. Over the next year, he had multiple readmissions for recurrent sepsis from culture negative multi-focal abscesses. Serial CT scans revealed new abscesses in the liver, scrotum, and lungs with interval progression in size. Unsuccessful attempts to isolate a culprit organism which included serological markers and cultures from blood, bronchial washings, aspirate from abscesses, and surgical tissue. All samples demonstrated frank pus with suppurative granulomatous inflammation. The patient was trialed on various courses of antibiotics without improvement. Therefore, a decision was made to treat for AAS given his IBD history. Antibiotics were discontinued and prednisone was initiated with rapid improvement in symptoms and biochemistry. In the three years following, he was transitioned to a combination of infliximab and azathioprine. He had rapid resolution of his abscesses on serial CT scans following steroid and anti-TNF therapy. Currently, he is no longer on steroids and his CRP has normalized with no recurrence of his symptoms.

Conclusions

AAS has often been associated with IBD, particularly Crohn’s disease and more rarely in UC. Case series have shown that AAS is not strongly associated with IBD activity as only 55% of cases have concomitant IBD flare and abscess formation. The syndrome continues to pose a diagnostic conundrum among specialists as there is no established diagnostic criteria and thus AAS remains a diagnosis of exclusion. This has led many patients to suffer from AAS for prolonged periods and receive unnecessary investigations and treatments. Steroids remain the gold standard for initial induction of remission. However, the ideal regimen for maintenance therapy is still evolving and case reports have described the effects of immunotherapy and biologics on AAS. AAS has a substantial impact on quality of life and is very responsive to therapy; this case report reminds the clinician that AAS should be considered in patients with IBD presenting with multifocal abscesses unresponsive to antimicrobials.

Serial CT scan (coronal view) of abdomen demonstrating multiple hepatic abscesses (blue arrows)

Funding Agencies

None

Vitamin B-12 supplementation improves arterial function in vegetarians with subnormal vitamin B-12 status

OBJECTIVE

Vegetarians are more vascular-healthy but those with subnormal vitamin B-12 status have impaired arterial endothelial function and increased intima-media thickness. We aimed to study the impact of vitamin B-12 supplementation on these markers, in the vegetarians.

DESIGN

Double-blind, placebo controlled, randomised crossover study.

SETTING

Community dwelling vegetarians.

PARTICIPANTS

Fifty healthy vegetarians (vegetarian diet for at least 6 years) were recruited.

INTERVENTION

Vitamin B-12 (500 µg/day) or identical placebo were given for 12 weeks with 10 weeks of placebo-washout before crossover (n=43), and then open label vitamin B-12 for additional 24 weeks (n=41).

MEASUREMENT

Flow-mediated dilation of brachial artery (FMD) and intima-media thickness (IMT) of carotid artery were measured by ultrasound.

RESULTS

The mean age of the subjects was 45±9 years and 22 (44%) were male. Thirty-five subjects (70%) had serum B-12 levels <150 pmol/l. Vitamin B-12 supplementation significantly increased serum vitamin B-12 levels (p<0.0001) and lowered plasma homocysteine (p<0.05). After vitamin B-12 supplementation but not placebo, significant improvement of brachial FMD (6.3±1.8% to 6.9±1.9%; p<0.0001) and in carotid IMT (0.69±0.09 mm to 0.67±0.09 mm, p<0.05) were found, with further improvement in FMD (to 7.4±1.7%; p<0.0001) and IMT (to 0.65±0.09 mm; p<0.001) after 24 weeks open label vitamin B-12. There were no significant changes in blood pressures or lipid profiles. On multivariate analysis, changes in B-12 (β=0.25; p=0.02) but not homocysteine were related to changes in FMD, (R=0.32; F value=3.19; p=0.028).

CONCLUSIONS

Vitamin B-12 supplementation improved arterial function in vegetarians with subnormal vitamin B-12 levels, proposing a novel strategy for atherosclerosis prevention.

Wnt-signaling mediates the anti-adipogenic action of lysophosphatidic acid through cross talking with the Rho/Rho associated kinase (ROCK) pathway

Lysophosphatidic acid (LPA) is a bioactive phospholipid with a diverse range of biological activities including the modulation of adipogenesis. Treatment of 3T3-L1 cells and 3T3F44A cells with LPA inhibits adipogenesis and reduces expression of PPARγ through activation of RhoGTPase and its downstream Rho associated kinase (ROCK). The mechanism of suppression of PPARγ expression by Rho/ROCK is poorly understood. By treating the differentiating 3T3-L1 cells with various combinations of LPA and ROCK inhibitors, Y-27632 and fasudil, we observed that LPA treatment resulted in attenuation of adipogenesis and a significant reduction in PPARγ mRNA as early as 3 d post-induction. LPA treatment also resulted in significant but delayed upregulation of components of the canonical Wnt signaling, namely Wnt10b mRNA, β-catenin protein, and mRNA expression of β-catenin target genes, detectable at day 7, but not day 3. Treatment of the 3T3-L1 cells with ROCK inhibitors Y-27632 and fasudil revealed a tonic activation of β-catenin/target genes by ROCK. This study identified the existence of a novel cross talk between the Rho/ROCK pathway and the Wnt-signaling pathway. The LPA/Rho/ROCK pathway inhibits expression of PPARγ and adipogenesis in part through a delayed activation of the canonical Wnt-signaling pathway based on increased Wnt10b expression and β-catenin induction.

Dioxin furan blood lipid and attic dust concentrations in populations living near four wood treatment facilities in the United States

To evaluate historical exposure from wood treatment facilities, attic dust samples were collected from residential structures and blood samples were collected from current and past residents of four communities surrounding wood treatment facilities throughout the United States. The pattern of dioxin/furan congeners detected in both attic dust and blood samples was found to be consistent with exposure to contaminants generated during the wood treatment process. Levels in the U.S. population of 2,3,7,8-tetrachloro-p-dibenzodioxin toxic equivalents (2,3,7,8-TCDD TEQs) for all 17 carcinogenic dioxin/furan congeners as well as octa-chlorinated dibenzo-p-dioxin (OCDD) adjusted to its TEQ value and 1,2,3,4,6,7,8-hepta-chlorinated dibenzo-p-dioxin (1,2,3,4,6,7,8-HpCDD) adjusted to its TEQ value were compared to the TEQ levels in the combined data set for all four communities and in the data sets for each individual community. TEQ concentrations in these communities were found to be significantly greater than in the general U.S. population. The levels of dioxins in attic dust were compared to the U.S. Environmental Protection Agency's regional screening levels and found to far exceed the levels that are regarded as safe for the general population. These findings reveal that a very significant potential for contaminant-related health risks exists in communities surrounding wood treatment facilities.

Microleakage of Posterior Composite Restorations Lined with Self-adhesive Resin Cements

Two self-adhesive resin cements resulted in minimal microleakage scores when used as liners in Class II composite restorations.

Expression levels of the JAK/STAT pathway in the transition from hormone-sensitive to hormone-refractory prostate cancer

The main cause of prostate cancer-related mortality is the development of hormone-refractory disease. Circulating serum levels of IL-6 are raised in hormone-refractory prostate cancer patients and evidence from cell line studies suggests that the IL-6R/JAK/STAT3 pathway may be involved in development of this disease. In the current study we investigate if expression levels of these family members are implicated in the development of hormone-refractory prostate cancer. Immunohistochemistry using IL-6R, JAK1, STAT3, pSTAT3(Tyr705) and pSTAT3(Ser727) antibodies was performed on 50 matched hormone-sensitive and hormone-refractory tumours pairs. An increase in expression of cytoplasmic IL-6 receptor, with the development of hormone-refractory prostate cancer was associated with reduced time to relapse (P=0.0074) while an increase in expression of cytoplasmic pSTAT3(Tyr705) was associated with reduced patient survival (P=0.0003). In addition, those patients with high expression of cytoplasmic pSTAT3(Tyr705) in their hormone-refractory tumours had significantly shorter time to death from biochemical relapse and overall survival in comparison to those patients with low expression of cytoplasmic pSTAT3(Tyr705) (P=0.002 and P=0.0027, respectively). Activation of STAT3, via phosphorylation is associated with reduced patient survival, suggesting that activation of the IL-6R/JAK/STAT3 pathway is involved with development of hormone-refractory prostate cancer.

Observer variation in immunohistochemical analysis of protein expression, time for a change?

AIM

Immunohistochemical analysis of protein expression is central to most clinical translational studies and defines patient treatment or selection criteria for novel drugs. Interobserver variation is rarely analysed despite recognition that this is a key area of potential inaccuracy. Therefore our aim was to examine observer variation and suggest the revision of current standards.

METHODS AND RESULTS

We analysed inter- and intra-observer variation, by interclass correlation coefficient (ICCC) and kappa statistics, in 8661 samples. Intra-observer assessment of nuclear, cytoplasmic and membrane staining for seven proteins in 1323 samples resulted in an ICCC of 0.94 and a kappa-value of 0.787. Interobserver reproducibility, assessed on 28 proteins by seven observer pairs in 8661 carcinomas, gave an ICCC of 0.90 and a kappa-value of 0.70. No significant effect of either antibody or cellular compartmentalization was observed.

CONCLUSION

We have demonstrated that ICCC is a consistent method to assess observer variation when a continuous scoring system is used, compared with kappa statistics, which depends on a categorical system. Given the importance of accurate assessment of protein expression in diagnostic and experimental medicine, we suggest raising thresholds for observer variation: ICCC of 0.7 should be regarded as the minimum acceptable standard, ICCC of 0.8 as good and ICCC of > or = 0.9 as excellent.

Effect of potassium nitrate and fluoride on carbamide peroxide bleaching

OBJECTIVES

The purpose of this study was to assess the effect on tooth sensitivity when potassium nitrate and fluoride were added to a 10% carbamide peroxide bleaching gel.

METHOD AND MATERIALS

Seventeen maxillary and four mandibular arches were bleached using the at-home bleaching technique. The bleaching treatment consisted of the simultaneous use of a 10% carbamide peroxide gel containing 3% potassium nitrate wt/vol and 0.11 fluoride ion wt/vol on one side of the midline and a 10% carbamide peroxide gel only (control) on the other side of the midline for 14 nights. A visual analog scale for each side of the dental arch was used by the patients to assess tooth sensitivity and tooth whitening. Preoperative and postoperative photographs were also taken.

RESULTS

The addition of potassium nitrate and fluoride significantly decreased the total tooth sensitivity reported by the patients. The addition did not significantly change the whitening efficacy of the carbamide peroxide bleach.

CONCLUSION

A 10% carbamide peroxide bleaching gel containing potassium nitrate and fluoride produced less tooth sensitivity than did the control bleaching gel during a 2-week at-home bleaching treatment.

Can critically timed sleep deprivation be useful in pregnancy and postpartum depressions?

BACKGROUND

The aim of this study was to test the efficacy of critically timed sleep deprivation in major mood disorders (MMD) occurring during pregnancy and postpartum.

METHODS

Nine women who met DSM-IV criteria for a MMD with onset during pregnancy or within 1 year postpartum underwent a trial of either early-night sleep deprivation (ESD), in which they were sleep deprived in the early part of one night and slept from 03:00-07:00 h, or late-night sleep deprivation (LSD), in which they were deprived of sleep in the latter part of one night and slept from 21:00-01:00 h. Mood was assessed before the night of sleep deprivation, after the night of sleep deprivation, and after a night of recovery sleep (sleep 22:30-06:30 h) by trained clinicians, blind to treatment condition, using standardized scales.

RESULTS

More patients responded to LSD (nine of 11 trials: 82%) compared with ESD (two of six trials: 33%) and they responded more after a night of recovery sleep (nine of 11 nights: 82%) than after a night of sleep deprivation (six of 11 nights: 55%). Pregnant women were the only responders to ESD and the only nonresponders to LSD.

LIMITATIONS

The small and heterogeneous sample size prevents us from making more definitive conclusions based on statistical analyses.

CONCLUSIONS

Although the findings are preliminary, the results suggest that with further study, critically timed sleep deprivation interventions may benefit women with pregnancy or postpartum major mood disorders and potentially provide a viable alternative treatment modality for those women who are not candidates for pharmacologic or psychotherapeutic interventions. Such interventions are needed to help prevent the devastating effects of depression during pregnancy and the postpartum period on the mother, infant, her family and society.

Patients' and providers' perceptions of outpatient treatment termination in a managed behavioral health organization

OBJECTIVE

A common complaint about managed care is that treatment decisions of patients and providers are frequently altered by concurrent review of ongoing outpatient treatment. The objective of this study was to examine this perception from the perspectives of patients and providers.

METHODS

A total of 190 patients and their providers were surveyed about the reason that outpatient treatment was terminated. The sample was randomly drawn from completed outpatient treatment episodes of a large national managed behavioral health organization.

RESULTS

In more than three-quarters of the cases, outpatient treatment ended because patients and providers agreed that treatment goals were partially or completely met. Only 5 percent of patients and 3 percent of providers said that treatment ended because the managed care organization denied ongoing treatment. Agreement between patient-provider pairs was generally poor regarding the perceived reason for termination, except when termination was attributed to concurrent review by the managed behavioral health organization.

CONCLUSIONS

In this study of a single large managed behavioral health organization, outpatient treatment was most likely to end based on the decisions of patients and providers rather than utilization review decisions.

Clinical trial of three 10% carbamide peroxide bleaching products

BACKGROUND

A profusion of commercial bleaching systems exists on the market today, but there are few clinical comparisons of these systems.

METHODS

In this study, three different commercial 10% carbamide peroxide bleaching systems were used by 24 patients in an overnight protocol for two weeks. Each patient used two of the bleaching products simultaneously in a side-by-side comparison.

RESULTS

The mean onset of tooth whitening was 2.4 +/- 1.7 days. Tooth sensitivity was the most frequent side effect, as 64% of the patients reported tooth sensitivity occurring after 4.8 +/- 4.1 days and lasting for 5.0 +/- 3.8 days. Although intrapatient differences were recorded for the three commercial 10% carbamide peroxide bleaching systems by the patients, there were no statistical differences in the time of onset of subjective tooth whitening and the onset, frequency and duration of tooth sensitivity among the three commercial bleaching systems when compared pairwise or independently (p < 0.05).

CONCLUSION

Selection of which bleaching product to use should be based on the concentration of the active ingredient, the viscosity of the product and other marketing features. Further research is needed to investigate the causes of tooth sensitivity and methods to reduce its severity and frequency.

Outreach, consolidation, and networking: Columbia's approach to successful integration of laboratory services in California

At the forefront of integrated laboratory services, Columbia Bay Area Healthcare Network's Lab Link provides a unique approach to operating hospital-based laboratories in today's heavily penetrated managed-care environment. Columbia recognizes that a combined strategy of laboratory consolidation, outreach, and networking is essential to compete successfully with commercial reference laboratories for local and statewide contracts. Implementing this model enables hospital laboratories to produce high quality, cost-effective test results while increasing volume and reducing duplication. When hospital laboratories consolidate and network with local and regional laboratories, inpatient and outpatients information is cross-fertilized through a web of information systems. Patients information can then be accessed easily and monitored throughout the continuum of care. The goal of this article is to provide hospital laboratories with a streamlined approach to structuring and delivering services while maintaining a competitive edge in the tumultuous healthcare market. The future of laboratory services within the hospital setting lies in the aggressive use of three elements--consolidation, outreach, and networking--to ensure quality service as well as economic viability.

Antinociception produced by oral, subcutaneous or intrathecal administration of SC-39566, an opioid dipeptide arylalkylamide, in the rodent

This study characterized the prototypic "minimum structure" enkephalin SC-39566 [2,6-dimethyl-L-tyrosinyl-D-alanine-(3-phenyl-1-propyl)-amide hydrochloride]. SC-39566 bound with highest affinity to mu opioid receptors (Ki, 0.13 nM), as well as to delta (Ki, 4.0 nM) opioid receptors in the rat brain, and with much lower affinity to kappa opioid receptors (Ki, 83.8 nM) in the guinea pig brain. In the mouse, SC-39566 inhibited phenylbenzoquinone-induced writhing and increased tail-flick and hot-plate latencies in a dose-dependent manner after either s.c. or p.o. (i.g.; intragastrical) administration. This antinociception was antagonized by the opioid antagonist naloxone, but not by alpha adrenergic, serotonergic, histaminergic, muscarinic cholinergic or dopaminergic receptor antagonists. In the rat, SC-39566 dose-dependently inhibited acetic-acid-induced writhing after s.c. or i.g. administration and increased response latencies in the tail-flick and hot-plate test after s.c. or intrathecal (i.t.) administration. The increase in tail-flick latency produced by s.c. SC-39566 in the rat was antagonized by s.c. naloxone with an apparent pA2 value of 7.9. Pretreatment with naltrindole, a delta opioid receptor antagonist, increased the ED50 of SC-39566 by only 1.7-fold. In addition, the increase in tail-flick latency produced by i.t. SC-39566 was not antagonized by i.t. administration of naltrindole or nor-binaltorphimine, a kappa receptor antagonist. These data suggest that the antinociceptive activity of SC-39566 is mediated predominantly by mu opioid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

CHWs trained in ARI management

Regular supervision and refresher trainings were the key to the success of a CHW (community health worker) training program in rural Bolivia. Since 1988, with the support of PLAN International, volunteer CHWs have been trained in 115 villages in Sucre, a rural health area lacking adequate health centers. CHWs educate the community, diagnose and treat pneumonia and refer severe cases to health centers or hospitals. CHWs who were already working on diarrheal disease control were chosen for the acute respiratory infection (ARI) case management training. A 3-day training program was organized for individual CHWs in their own homes and communities. The course included practicing on real ARI cases under the trainer's supervision. Since the program started, community respect for CHWs has risen. In one remote village, community leaders reported a marked improvement in child survival. Factors which explain the positive effects of CHWs include: a limited number of clearly defined tasks, provision of one-on-one appropriate training, periodic refresher courses, and continuous supervision. The main problems have been a lack of constant supply of essential drugs and some CHWs over-diagnosing pneumonia. However, once diagnosis is made, CHWs are careful about giving the correct antibiotic doses and instructions to mothers. Refresher training and supervision have helped to correct these initial problems. PLAN International and the Ministry of Health have organized supervision and training meetings every 2 months. The CHWs bring to these meetings reports of children treated and referred. Case management is analyzed, resupply of essential medicines is arranged and those with special problems are scheduled for a supervisory visit.

Evidence for chemical differentiation of delta opioid receptor subtypes by the sulfhydryl reagent N-ethylmaleimide

In this study, the delta receptor-selective nonequilibrium affinity ligands, 5'-NTII and DALCE, and the nonspecific sulfhydryl reagent NEM were evaluated over a range of concentrations and treatment conditions for their ability to selectively alter the binding properties of delta 1- or delta 2-preferring opioid radioligands in brain homogenate. Treatment of tissue preparations with DALCE (0-10,000 nM) or NTII (0-10,000 nM) resulted in an equivalent concentration-dependent loss of binding capacity for the delta 1 agonist 3H-DPDPE and the mu/delta 2 agonist 3H-DSLET. In contrast, treatment of tissue with NEM (0-8000 microM) resulted in greater loss of 3H-DPDPE binding. Scatchard analysis of the binding of 3H-DPDPE, 3H-DSLET, and 3H-NTI in 3 mM NEM-treated rat brain P2 preparation revealed an equivalent decrease in affinity for the agonist ligands, but a significantly greater decrease in Bmax for 3H-DPDPE compared with control tissue values. Comparison of the K(i) values for a series of delta-selective compounds against 3H-DSLET binding in control vs 3 mM NEM treated P2 fraction showed differential effects of NEM on affinity within the series that were consistent with a selective depletion of delta 1 sites. Overall, these results indicate that NEM treatment selectively reduced delta 1 receptor binding, resulting in a preparation that is enriched in delta 2 sites.

[3H]naltrindole: a potent and selective ligand for labeling delta-opioid receptors

Naltrindole (NTI) is a selective and potent delta-opioid antagonist which preferentially antagonizes a subset of selective delta-opioid agonists. The purpose of this study was to evaluate whether [3H]NTI, the first radiolabeled delta-opioid antagonist, could selectively label delta-opioid receptors in a synaptosomal preparation. Increasing temperature and protein concentration (0.1-1.6 mg protein) increased the specific binding of [3H]NTI. Monovalent and divalent cations (0.01-100 mM) had minimal effects on the binding properties of [3H]NTI, in contrast to their effects on binding of the delta agonists [3H]DPDPE and [3H]DSLET. Subfractionation of rat brain homogenates revealed that [3H]NTI and [3H]DSLET primarily labeled binding sites in synaptosomal and microsomal fractions, whereas [3H]DPDPE labelled half as many sites in synaptosomal fraction. The Bmax determined for [3H]NTI in crude synaptosomal fraction was 95 +/- 12 fmol/mg. The dissociation constant (Kd) was determined from three different methods to be 0.08 +/- 0.02 nM (Scatchard analysis), 0.07 +/- 0.02 nM (competition study) and 0.03 +/- 0.005 nM (kinetic analysis). [3H]NTI binding was not significantly inhibited by mu- or kappa-opioid ligands or by nonopioid compounds. These results demonstrate that [3H]NTI is a potent and selective radioligand for delta-opioid receptors in rat brain preparations.

Vital tooth bleaching: review and current status

Vital tooth bleaching refers to the clinical application of a chemical solution to a tooth surface in order to achieve a lightening effect. This article reviews the available literature to address the following questions: What are the methods of vital bleaching? How does vital bleaching work and is it effective? What effects are there on the teeth, dental restorative materials, soft tissues and systemic health? The techniques used in the application of dentist-applied and patient-applied bleaching systems are described. Generally, vital tooth bleaching has been found to be effective, however, relapse does occur. The literature suggests that bleaching agents may have transient effects on the tooth itself, and may affect some dental materials. Soft tissues exposed to hydrogen peroxide for prolonged periods show changes consistent with inflammation or hyperplasia. Hydrogen peroxide may also potentiate the carcinogenic effect of known carcinogens. However, more clinically relevant studies are needed. Until long-term safety data becomes available, the dental practitioner should approach the use of in-home bleaches with caution. The U.S. Food and Drug Administration (FDA) recently classified these products as "new drug." However, dentist-applied bleaching gel systems are a viable alternative and deserve further consideration. They are simple to use, require little armamentarium, and limit the exposure of the bleaching agent to the teeth only. Vital tooth bleaching refers to the clinical application of a chemical solution to a tooth surface in order to achieve a lightening effect. There was a resurgence of interest in vital bleaching with the recent introduction of the in-home bleaching technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Exonuclease V from Saccharomyces cerevisiae. A 5'----3'-deoxyribonuclease that produces dinucleotides in a sequential fashion

A novel deoxyribonuclease, exonuclease V, has been purified approximately 30,000-fold from Saccharomyces cerevisiae. Exonuclease V is localized in the nucleus. The nuclease degrades single-stranded, but not double-stranded, DNA from the 5'-end. The products of exonuclease action are dinucleotides, except the 3'-terminal tri- and tetranucleotides which are not degraded. Studies with synthetic oligo- and polynucleotides with specified sequence elements showed that exonuclease V cleaves off dinucleotides as primary digestion products. Thus, the polymers (pT)9pA(pT)n and (pT)10pA(pT)n yielded pTpA and pApT as digestion products, respectively. Removal of the 5'-terminal phosphate from the DNA substrate results in reduced binding of the enzyme to the substrate. In addition, the initial hydrolytic cut by exonuclease V on the dephosphorylated substrate produces a mixture of dinucleoside monophosphates and trinucleoside diphosphates. The enzyme is processive in action.

Trimethaphan camsylate (Arfonad) and human plasma cholinesterase

These results for the first time document that the brief duration of action of the ganglionic blocker, Arfonad (trimethaphan camsylate), is not due to inactivation by plasma cholinesterase. Inhibition of the enzyme in vitro by Arfonad was not altered by prior incubation of the drug in plasma at 37 degrees C for up to 16 hours nor by treatment with NaOH at 100 degrees C for 10 minutes. Both procedures inactivated succinylcholine. These results in vitro were confirmed in vivo by finding that the toxicity of Arfonad in mice was not significantly altered by these procedures whereas they rendered succinylcholine inocuous. Arfonad is a noncompetitive whereas succinylcholine is a competitive inhibitor of plasma cholinesterase using benzoylcholine as the substrate. The camphorsulfonate moiety of Arfonad was inactive in vitro but caused mild tremors in mice at relatively high doses.