Hepatic Cystic Echinococcosis (Hydatid Cyst) in a Six Year Old

Presentation To describe a case of cystic echinococcosis (CE) in a previously healthy child and review epidemiology of CE in Ireland. Diagnosis A previously healthy 6 year old girl was found to have a cystic lesion in the right lobe of her liver. Serology for Echinococcus granulosus was positive, and radiological features were suggestive of CE. Treatment The patient was pre-treated with anti-helminthic medications before undergoing a liver segmentectomy to remove the cyst, and received further treatment with albendazole after surgery. Histological findings were consistent with CE due to E. granulosus, likely acquired during travel to continental Europe. Conclusion CE should be considered in the differential of children with asymptomatic cysts in the liver and/or lung, and a travel history elucidated in such cases.

A Phase II Trial of Dovitinib in BCG-Unresponsive Urothelial Carcinoma with FGFR3 Mutations or Overexpression: Hoosier Cancer Research Network Trial HCRN 12-157

Purpose: To assess the clinical and pharmacodynamic activity of dovitinib in a treatment-resistant, molecularly enriched non-muscle-invasive urothelial carcinoma of the bladder (NMIUC) population.Experimental Design: A multi-site pilot phase II trial was conducted. Key eligibility criteria included the following: Bacillus Calmette-Guerin (BCG)-unresponsive NMIUC (>2 prior intravesical regimens) with increased phosphorylated FGFR3 (pFGFR3) expression by centrally analyzed immunohistochemistry (IHC+) or FGFR3 mutations (Mut+) assessed in a CLIA-licensed laboratory. Patients received oral dovitinib 500 mg daily (5 days on/2 days off). The primary endpoint was 6-month TURBT-confirmed complete response (CR) rate.Results: Between 11/2013 and 10/2014, 13 patients enrolled (10 IHC+ Mut-, 3 IHC+ Mut+). Accrual ended prematurely due to cessation of dovitinib clinical development. Demographics included the following: median age 70 years; 85% male; carcinoma in situ (CIS; 3 patients), Ta/T1 (8 patients), and Ta/T1 + CIS (2 patients); median prior regimens 3. Toxicity was frequent with all patients experiencing at least one grade 3-4 event. Six-month CR rate was 8% (0% in IHC+ Mut-; 33% in IHC+ Mut+). The primary endpoint was not met. Pharmacodynamically active (94-5,812 nmol/L) dovitinib concentrations in urothelial tissue were observed in all evaluable patients. Reductions in pFGFR3 IHC staining were observed post-dovitinib treatment.Conclusions: Dovitinib consistently achieved biologically active concentrations within the urothelium and demonstrated pharmacodynamic pFGFR3 inhibition. These results support systemic administration as a viable approach to clinical trials in patients with NMIUC. Long-term dovitinib administration was not feasible due to frequent toxicity. Absent clinical activity suggests that patient selection by pFGFR3 IHC alone does not enrich for response to FGFR3 kinase inhibitors in urothelial carcinoma. Clin Cancer Res; 23(12); 3003-11. ©2016 AACR.

Partnering for Success: Expanding Breast and Cancer Screening in Rural Honduras One Clinic at a Time

Abstract 36

Background:

Women in rural Honduras have limited access to cancer education, screening, and care. With village leaders, we piloted breast and cervical cancer screening in El Rosario, Honduras. Our objectives were to improve awareness and access, mitigate barriers, connect community and Honduran providers, and link patients with abnormal findings to cancer treatment. In 2013, health professionals and staff from Norris Cotton Cancer Center at Dartmouth- Hitchcock joined Honduran clinicians and medical students from La Liga Contra el Cáncer for two days of rural cancer screening. Peer educators taught 475 participants from 31 rural communities how to conduct self-breast exams. Of these participants, 238 chose clinical breast exams; 5% were clinically abnormal and 2.9% were referred for services at La Liga with 100% compliance. 34% reported barriers to cervical cancer screening due to distance and lack of transportation. 14.5% tested positive for HPV and 8% were positive for high risk HPV genotypes including 11 of 13 known high risk types. This group has been retested periodically by Pap. The collaborators will return in April 2016 to repeat the study, adding oral and thyroid screening. Genotyping for hrHPV will be onsite with a novel assay for PCR developed at Dartmouth-Hitchcock. Reflex testing with Pap will follow as needed. Follow up will be at La Liga where care is offered for free or at a reduced cost. A similar project for 400 urban factory-workers will also take place in April 2016.

Methods:

2-day, multi-modal education and screening outreach run brigade-style combining low-tech primary screening with onsite molecular pathology.

Conclusions:

Partnerships between local leaders and clinicians are predicted to be essential to project implementation. Targeting populations with education and screening plus building connections to follow up care will provide earlier detection of breast and cervical cancer. We predict that community leadership will be critical to preventing loss to follow-up.

AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST:

Derek S. Stenquist No relationship to disclose Suyapa Bejarano No relationship to disclose Linda S. Kennedy No relationship to disclose Silvia Portillo No relationship to disclose Ana Barrientos No relationship to disclose Suzanne P. Burgos No relationship to disclose Roberto Armando Elvir Zelaya No relationship to disclose Christine Averill No relationship to disclose Emmeline Liu No relationship to disclose Francine de Abreau No relationship to disclose Paul Burchard No relationship to disclose Torrey Gallagher No relationship to disclose Martha Goodrich No relationship to disclose Scottie Eliassen No relationship to disclose Julie Weiss No relationship to disclose Camilo Mandujano No relationship to disclose Jennifer Alford-Teaster No relationship to disclose Gregory J. Tsongalis Research Funding: Illumina, Qiagen, Thermofisher Tracy Onega No relationship to disclose Mary D. Chamberlin No relationship to disclose

A Multistate Model for the Fluorescence Response of R-Phycoerythrin

Although strong fluorescence makes the R-phycoerythrin (R-PE) proteins increasingly useful in biological and clinical assays, they are subject to nonlinear effects including transitions to collective dark states and photodegradation, which complicate quantitative applications. We report measurements of R-PE fluorescence intensity as a function of incident power, duration of illumination and temperature. Emission intensity in the band at 570 nm is proportional to incident power for low power levels. At higher incident power, the emission at 570 nm is smaller than expected from a linear dependence on power. We propose that R-PE undergoes both reversible emission cessation on a millisecond time scale attributed to transitions to a collective dark state, and irreversible photodegradation on a time scale of minutes. Singlet oxygen scavengers such as dithiothreitol and n-propyl gallate have protective effects against the latter effect but not the former. Electrophoretic analysis of irradiated solutions of R-PE indicates that significant noncovalent aggregation is correlated with photodegradation. A multistate model based on fluorescence measurements and geometric analysis is proposed for the fluorophores in R-PE. The phycobilin fluorophores are partitioned into three groups: the phycourobilins (PUB) absorbing at 490 nm, one group of phycoerythobilins (PEB) absorbing at 530 nm (PEB-530) and another group of PEB absorbing at 560 nm (PEB-560). The two processes that result in the loss of fluorescence intensity are most likely associated with the PEB-560 group.

Action of a library of O-glycosylation inhibitors on the growth of human colorectal cancer cells in culture

O-glycosylation is thought to play a significant role in the regulation of cell growth. However, only limited information is available, and few specific and selective inhibitors have been found. We have synthesized a library of O-glycosylation inhibitors based on benzyl-O-N-acetyl-D-galactosamine. These inhibitors were tested with an established series of human colorectal cancer cell lines, which model the adenoma-carcinoma sequence. Cancer cells were incubated with the inhibitors, and examined for cell growth patterns, and cellular and subcellular glycosylation using a range of lectins with confocal microscopy. The specificity of O-glycan inhibition was confirmed for the library, relative to other forms of glycosylation. All inhibitors tested resulted in smaller cell yields. However, a differential effect on O-glycosylation was detected using the lectins showing variation of localization at a subcellular level in the various cell lines. Further differential action of the inhibitor library was observed for apoptosis and on the cell cycle with the cell lines tested. This work demonstrates that O-glycosylation is closely involved in the regulation of cell growth in colorectal cancer cells and that the generation of a library of low-molecular-mass inhibitors offers a valuable means of examining this regulation at the molecular level.

Subtilisin BPN' at 1.6 A resolution: analysis for discrete disorder and comparison of crystal forms

The three-dimensional structure of the serine protease subtilisin BPN' (SBT) has been refined at 1.6 A resolution in space group C2 to a final R value of 0.17. 17 regions of discrete disorder have been identified and analyzed. Two of these are dual-conformation peptide units; the remainder involve alternate rotamers of side chains either alone or in small clusters. The structure is compared with previously reported high-resolution models of SBT in two other space groups, P2(1)2(1)2(1) and P2(1). Apart from the surface, there are no significant variations in structure among the three crystal forms. Structural variations observed at the protein surface occur predominantly in regions of protein-protein contact. The crystal packing arrangements in the three space groups are compared.

Unmet needs in groups of traditionally underserved individuals with HIV/AIDS: empirical models

Over the course of the HIV epidemic, the demographics of the populations of affected individuals have changed. Groups that traditionally have been underserved in systems of care have a number of unmet service needs. This article presents results based on data from 478 patients in five national demonstration projects which were funded to enroll individuals from traditionally underserved groups and to help them access services using different strategies. The participants in these programs had a high level of unmet need prior to enrolling in care. Data on client service needs were related to 17 indicators of traditionally underserved status including demographic characteristics and risk behaviors, using the data modeling method of Exhaustive CHAID (Chi-squared Automatic Interaction Detector). Crack cocaine users with HIV/AIDS were more likely than other patient groups to have unmet service needs. Patients who were homeless or in precarious housing also were vulnerable. Results are discussed in terms of designing and evaluating innovative service models to close these service gaps.

Perceived barriers to receiving HIV services in groups of traditionally underserved individuals: empirical models

Persons living with HIV/AIDS face many issues that make them highly vulnerable to a number of health and social problems. As the demographics of the epidemic have shifted in recent years, many members of traditionally underserved groups have encountered barriers to entering the services system. This article uses data from seven national demonstration projects funded to enroll persons with HIV/AIDS who tend to "fall through the cracks" and help them access needed services. Data on the initial perceptions of the participants about barriers to accessing services were related to 17 indicators of traditionally underserved status including demographic characteristics and behavioral variables using the data modeling method of Exhaustive CHAID (Chi-squared Automatic Interaction Detector). Through the modeling methods, the groups most likely to experience a large number of barriers to service participation are identified. Having children needing care is particularly predictive of the level of barriers to care.

Satisfaction with innovative community and university health clinic programs for groups of traditionally underserved individuals with HIV/AIDS: empirical models

As the demographics of the populations of affected individuals have changed, systems of care have needed to adapt to be responsive to client needs. This article examines client satisfaction data from seven national demonstration projects funded to enroll individuals from traditionally underserved groups and help them access services using different strategies. Data on client satisfaction ratings were related to indicators of traditionally underserved status, including demographic characteristics, behaviors, and other risk factors using the data modeling method of Exhaustive CHAID (Chi-squared Automatic Interaction Detector). Client groups that were most likely to experience relatively higher and lower levels of satisfaction with services are identified. Overall, all client groups were highly satisfied with the innovative HIV/AIDS services received. The findings illustrate the success of these innovative HIV care models in being responsive and sensitive to the needs of their target populations.

Finding the Underserved: Directions for HIV Care in the Future

The demographic, behavior, and background characteristics of 4,804 participants in 17 national demonstration projects for HIV medical and/or psychosocial support services were coded for an index of "service need" or possible under-representation in the traditional healthcare system. Fifteen items were coded including status as a person of color, lack of private insurance, unemployment/disability, problem drinking, crack cocaine use, heroin use, other illicit drug use, less than 12 years of education, criminal justice system involvement, children requiring care while the patient receives services, sex work, being the sex partner of an injection drug user, unstable housing, primary language not English, and age less than 21 or over 55 years. Most (87.7%) of the program participants had four or more of these factors present. Through CHAID modeling, those groups with the highest levels of service need and vulnerability were identified. These data suggest that these projects, designed to attract and serve individuals potentially underrepresented in the health services system, had in fact achieved that goal. Implications of the changing demographics of the HIV epidemic for the health service delivery system are discussed.

Directed deprotonation-transmetalation as a route to substituted pyridines

Regioselective C-4 deprotonation of 3-bromopyridine, followed by Li/Zn transmetalation and Pd-mediated coupling processes, provides a flexible entry to 4-substituted and 3,4-disubstituted pyridines. Application of a similar sequence to 2-bromopyridine (with LDA as base) provides 2,3-disubstituted pyridines, but using lithium 2,2,6,6-tetramethylpiperidide (LiTMP) provides access to both the 2,3- and 2,4-disubstituted isomers.

Typology of quality of life experiences among persons living with HIV

This article develops a typology of 2,038 participants in 13 innovative HIV/AIDS treatment model service demonstration projects targeted to traditionally underserved populations. The typology is based on self-reported health-related quality of life levels. Eight clusters were identified that classify HIV/AIDS patients based on their reported health-related quality of life. Participants were clustered based on their overall levels of quality of life, as well as by deficits in specific areas of functioning such as energy level, physical impairment, and role impairment. However, factor analysis suggests that health-related quality of life as perceived by the HIV-positive participants is best represented as a single underlying dimension and an ordering of the types shows that they are consistently related, in the same order, to several criterion measures of impairment. The results suggest that a general categorization of patients with HIV in terms of quality of life is more meaningful than an assessment of the relative areas of impairment. Since the impairment ratings were also self-reported, analyses relating quality of life clusters to actual symptom levels and healthcare utilization are needed. Implications for the assessment of health-related quality of life and the evaluation of service delivery programs for persons living with HIV are discussed.

Service needs and factors related to quality of life at time of service enrollment among persons living with HIV

This article explores the relationships of HIV risk factors, service needs, and vulnerabilities to health-related quality of life in a sample of 1,371 participants newly enrolled into 13 innovative HIV/AIDS treatment model service demonstration projects. These projects targeted services to traditionally underserved populations. Eight distinct quality of life clusters of HIV patients were used in this analysis along with patient self-identified risk factors. The quality of life clusters were based on patient self-reported quality of life dimensions. The eight clusters were differentiated based on relative strengths and weaknesses in physical functioning, energy levels, and social functioning. Data on patient need-vulnerability factors and demographic characteristics were related to these eight clusters using the data modeling method of Exhaustive CHAID (Chi-squared Automatic Interaction Detector). Through this method, the characteristics most likely to be associated with higher and lower levels of quality of life at the time of enrollment into services were identified. The results provide further support that quality of life assessment is a useful clinical tool for monitoring patient progress.

Radical-mediated synthesis of alpha-C-glycosides based on N-acyl galactosamine

[structure] C-Glycosides of N-acyl 2-amino-2-deoxygalactose (acyl = MeCO, CF(3)CO, t-BuOCO) are available in a stereoselective manner by trapping of an anomeric radical with an activated alkene. Using anomeric selenides, radical generation and trapping is carried out under conditions that avoid competitive reduction, and this chemistry has been applied to the synthesis of the novel C-glycoside analogue of O-benzyl alpha-D-GalNAc.

UB-165: a novel nicotinic agonist with subtype selectivity implicates the alpha4beta2* subtype in the modulation of dopamine release from rat striatal synaptosomes

Presynaptic nicotinic acetylcholine receptors (nAChRs) on striatal synaptosomes stimulate dopamine release. Partial inhibition by the alpha3beta2-selective alpha-conotoxin-MII indicates heterogeneity of presynaptic nAChRs on dopamine terminals. We have used this alpha-conotoxin and UB-165, a novel hybrid of epibatidine and anatoxin-a, to address the hypothesis that the alpha-conotoxin-MII-insensitive subtype is composed of alpha4 and beta2 subunits. UB-165 shows intermediate potency, compared with the parent molecules, at alpha4beta2* and alpha3-containing binding sites, and resembles epibatidine in its high discrimination of these sites over alpha7-type and muscle binding sites. (+/-)-Epibatidine, (+/-)-anatoxin-a, and (+/-)-UB-165 stimulated [(3)H]-dopamine release from striatal synaptosomes with EC(50) values of 2.4, 134, and 88 nM, and relative efficacies of 1:0.4:0.2, respectively. alpha-Conotoxin-MII inhibited release evoked by these agonists by 48, 56, and 88%, respectively, suggesting that (+/-)-UB-165 is a very poor agonist at the alpha-conotoxin-MII-insensitive nAChR subtype. In assays of (86)Rb(+) efflux from thalamic synaptosomes, a model of an alpha4beta2* nAChR response, (+/-)-UB-165 was a very weak partial agonist; the low efficacy of (+/-)-UB-165 at alpha4beta2 nAChR was confirmed in Xenopus oocytes expressing various combinations of human nAChR subunits. In contrast, (+/-)-UB-165 and (+/-)-anatoxin-a were similarly efficacious and similarly sensitive to alpha-conotoxin-MII in increasing intracellular Ca(2+) in SH-SY5Y cells, a functional assay for native alpha3-containing nAChR. These data support the involvement of alpha4beta2* nAChR in the presynaptic modulation of striatal dopamine release and illustrate the utility of exploiting a novel partial agonist, together with a selective antagonist, to dissect the functional roles of nAChR subtypes in the brain.

Mouse hepatitis virus strain JHM infects a human hepatocellular carcinoma cell line

Mouse hepatitis virus (MHV) strain JHM is a coronavirus that causes encephalitis and demyelination in susceptible rodents. The known receptors for MHV are all members of the carcinoembryonic antigen family. Although human forms of the MHV receptor can function as MHV receptors in some assays, no human cell line has been identified that can support wild-type MHV infection. Here we describe the infection of a human hepatocellular carcinoma cell line, HuH-7, with MHV. HuH-7 cells were susceptible to strains JHM-DL and JHM-DS, yielding virus titers nearly identical to those seen in mouse DBT cells. In contrast, HuH-7 cells were only marginally susceptible or completely resistant to infection by other MHV strains, including A59. JHM produced a strong cytopathic effect in HuH-7 cells with the formation of round plaques. Studies of various recombinant viruses between JHM and A59 strains suggested that the ability of JHM to infect HuH-7 cells was determined by multiple viral genetic elements. Blocking the viral spike (S) protein with a neutralizing antibody or a soluble form of the MHV receptor inhibited infection of HuH-7 cells, suggesting that infection is mediated through the S protein. Transfection with the prototype mouse receptor, biliary glycoprotein, rendered HuH-7 cells susceptible to infection by other MHV strains as well, suggesting that JHM uses a receptor distinct from the classical MHV receptor to infect HuH-7 cells. Possible implications for human disease are discussed.

Crystal structure of calcium-independent subtilisin BPN' with restored thermal stability folded without the prodomain

The three-dimensional structure of a subtilisin BPN' construct that was produced and folded without its prodomain shows the tertiary structure is nearly identical to the wild-type enzyme and not a folding intermediate. The subtilisin BPN' variant, Sbt70, was cloned and expressed in Escherichia coli without the prodomain, the 77-residue N-terminal domain that catalyzes the folding of the enzyme into its native tertiary structure. Sbt70 has the high-affinity calcium-binding loop, residues 75 to 83, deleted. Such calcium-independent forms of subtilisin BPN' refold independently while retaining high levels of activity [Bryan et al., Biochemistry, 31:4937-4945, 1992]. Sbt70 has, in addition, seven stabilizing mutations, K43N, M50F, A73L, Q206V, Y217K, N218S, Q271E, and the active site serine has been replaced with alanine to prevent autolysis. The purified Sbt70 folded spontaneously without the prodomain and crystallized at room temperature. Crystals of Sbt70 belong to space group P2(1)2(1)2(1) with unit cell parameters a = 53.5 A, b = 60.3 A, and c = 83.4 A. Comparison of the refined structure with other high-resolution structures of subtilisin BPN' establishes that the conformation of Sbt70 is essentially the same as that previously determined for other calcium-independent forms and that of other wild-type subtilisin BPN' structures, all folded in the presence of the prodomain. These findings confirm the results of previous solution studies that showed subtilisin BPN' can be refolded into a native conformation without the presence of the prodomain [Bryan et al., Biochemistry 31:4937-4945, 1992]. The structure analysis also provides the first descriptions of four stabilizing mutations, K43N, A73L, Q206V, and Q271E, and provides details of the interaction between the enzyme and the Ala-Leu-Ala-Leu tetrapeptide found in the active-site cleft.

Crystal structure of calcium-independent subtilisin BPN' with restored thermal stability folded without the prodomain

The three-dimensional structure of a subtilisin BPN' construct that was produced and folded without its prodomain shows the tertiary structure is nearly identical to the wild-type enzyme and not a folding intermediate. The subtilisin BPN' variant, Sbt70, was cloned and expressed in Escherichia coli without the prodomain, the 77-residue N-terminal domain that catalyzes the folding of the enzyme into its native tertiary structure. Sbt70 has the high-affinity calcium-binding loop, residues 75 to 83, deleted. Such calcium-independent forms of subtilisin BPN' refold independently while retaining high levels of activity [Bryan et al., Biochemistry, 31:4937-4945, 1992]. Sbt70 has, in addition, seven stabilizing mutations, K43N, M50F, A73L, Q206V, Y217K, N218S, Q271E, and the active site serine has been replaced with alanine to prevent autolysis. The purified Sbt70 folded spontaneously without the prodomain and crystallized at room temperature. Crystals of Sbt70 belong to space group P2(1)2(1)2(1) with unit cell parameters a = 53.5 A, b = 60.3 A, and c = 83.4 A. Comparison of the refined structure with other high-resolution structures of subtilisin BPN' establishes that the conformation of Sbt70 is essentially the same as that previously determined for other calcium-independent forms and that of other wild-type subtilisin BPN' structures, all folded in the presence of the prodomain. These findings confirm the results of previous solution studies that showed subtilisin BPN' can be refolded into a native conformation without the presence of the prodomain [Bryan et al., Biochemistry 31:4937-4945, 1992]. The structure analysis also provides the first descriptions of four stabilizing mutations, K43N, A73L, Q206V, and Q271E, and provides details of the interaction between the enzyme and the Ala-Leu-Ala-Leu tetrapeptide found in the active-site cleft.

Cocaine users with antisocial personality improve HIV risk behaviors as much as those without antisocial personality

Previous work has documented that antisocial personality disorder (APD) is associated with increased rates of HIV risk behaviors and with worse substance abuse treatment outcomes. The question addressed by this paper is whether cocaine users with APD respond to an HIV risk-reduction intervention as well as cocaine users without the disorder. The study subjects were 333 cocaine users followed up at 18 months as part of a NIDA-funded treatment demonstration project. The total sample improved across a wide range of HIV risk behaviors. Improving significantly (P < 0.05) from baseline to the 18-month follow-up were several drug-related behaviors: cocaine use; current cocaine dependence; use of drugs other than cocaine drug injection; injection equipment sharing; and use of syringes that were not cleaned. Several sex-related HIV risk behaviors also improved significantly: having multiple sex partners; being intoxicated during sex; giving drugs for sex; receiving money for sex; and receiving drugs for sex. When the sample was stratified by APD status, very similar improvement was seen in respondents with and without APD. To examine further the relationship of APD to change in HIV risk behaviors, separate logistic regression models of improving and worsening HIV risk behaviors were tested. What the authors found was no association of APD with improvement in HIV risk behaviors but a significant association of APD with worsening HIV risk behaviors. It appears that cocaine users with APD improve their HIV risk behaviors just as much as those without APD but may be at higher HIV risk for the development of such behaviors.

Reliability of self-reported antisocial personality disorder symptoms among substance abusers

It is estimated that from 20 to 60% of substance abusers meet criteria for Antisocial Personality Disorder (APD). An accurate and reliable diagnosis is important because persons meeting criteria for APD, by the nature of their disorder, are less likely to change behaviors and more likely to relapse to both substance abuse and high risk behaviors. To understand more about the reliability of the disorder and symptoms of APD, the Diagnostic Interview Schedule Version III-R (DIS) was administered to 453 substance abusers ascertained from treatment programs and from the general population (St Louis Epidemiological Catchment Area (ECA) follow-up study). Estimates of the 1 week, test-retest reliability for the childhood conduct disorder criterion, the adult antisocial behavior criterion, and APD diagnosis fell in the good agreement range, as measured by kappa. The internal consistency of these DIS symptoms was adequate to acceptable. Individual DIS criteria designed to measure childhood conduct disorder ranged from fair to good for most items; reliability was slightly higher for the adult antisocial behavior symptom items. Finally, self-reported 'liars' were no more unreliable in their reports of their behaviors than 'non-liars'.

Diastereoselective resolution of 6-substituted glycosides via enzymatic hydrolysis

The diastereoselectivity of the enzymatic hydrolyses of 4-nitrophenyl 6-deoxy-6-methyl-(R)- and (S)-sulfinyl-beta-D-galactopyranoside (1a,b), 4-nitrophenyl 7-deoxy-D- and L-glycero-beta-D-galacto-heptopyranoside (2a,b) and 4-nitrophenyl 6,7-anhydro-D- and L-glycero-beta-D-galacto-heptopyranoside (3a,b) was investigated using a range of crude glycosidase preparations. It was shown that the enzymes display a high degree of discrimination between diastereomers thereby demonstrating the utility of glycosidases for the diastereomeric resolution of unnatural 6-substituted monosaccharide derivatives.

Bronchoalveolar lavage findings suggest two different forms of childhood asthma

BACKGROUND

It seems plausible that children with atopy and persistent asthma symptoms will, like their adult counterparts, have chronic airways inflammation. However, many young children with no other atopic features have episodic wheezing that is triggered solely by viral respiratory infections. Little is known as to whether airways inflammation occurs in these two asthma patterns during relatively asymptomatic periods.

METHODS

Using a non-bronchoscopic bronchoalveolar lavage (BAL) procedure on children presenting for an elective surgical procedure, this study has investigated the cellular constituents of BAL fluid in children with a history of atopic asthma (AA) non-asthmatic atopic children (NAA) or viral associated wheeze (VAW).

RESULTS

A total of 95 children was studied: 52 with atopic asthma (8.0 years, range 1.1-15.3, 36 male), 23 with non-asthmatic atopy (median age 8.3 years, range 1.7-13.6, 11 male) and 20 with VAW (3.1 years, range 1.0-8.2, 13 male). No complications were observed during the lavage procedure and no adverse events were noted post-operatively. Total lavage fluid recovered was similar in all groups and the total cell numbers were higher in the VAW group. Eosinophil (P < or = 0.005) and mast cell (P < or = 0.05) numbers were significantly elevated in the group with atopic asthma.

CONCLUSIONS

During relatively asymptomatic periods there is on-going airways inflammation, as demonstrated by eosinophil and mast cell recruitment, in children with asthma and atopy but not in children with viral associated wheeze or atopy alone. This strongly suggests that there are different underlying pathophysiological mechanisms in these two groups of children who wheeze.

Anatoxin-a-evoked [3H]dopamine release from rat striatal synaptosomes

Presynaptic nicotinic acetylcholine receptors on striatal nerve terminals modulate the release of dopamine. Using rat striatal synaptosomes loaded with [3H]dopamine, we have characterized the action of the selective nicotinic agonist, (+/-)anatoxin-a, with respect to [3H]dopamine release, in order to explore the mechanisms coupling nicotinic receptor activation to exocytosis. Anatoxin-a evoked [3H]dopamine release in a concentration-dependent and mecamylamine-sensitive manner, EC50 = 0.11 microM. The maximum [3H]dopamine release elicited by anatoxin-a was only 20% of the maximum elicited by KCl depolarization; there was no additivity between anatoxin-a and sub-maximal concentrations of KCl. Both agents stimulated Ca(2+)-dependent release that was equally sensitive to inhibition by 200 microM Cd2+. This result suggests that anatoxin-a-stimulated exocytosis is mediated by Ca2+ influx via voltage-sensitive Ca2+ channels, with little contribution from Ca2+ entering directly through the nicotinic receptor channel. This view is supported by the abolition of anatoxin-a-evoked [3H]dopamine release in Na(+)-depleted medium. A partial (40%) inhibition by tetrodotoxin was observed. These data suggest that activation of presynaptic nicotinic acetylcholine receptors by anatoxin-a results in an influx of Na+, producing sufficient local depolarization to open voltage-sensitive Ca2+ and Na+ channels. The latter may then amplify the response, activating further Ca2+ channels. The particular voltage-sensitive Ca2+ channels involved remain to be determined.

The prosegment-subtilisin BPN' complex: crystal structure of a specific 'foldase'

BACKGROUND

The folding of the bacterial protease subtilisin BPN' (SBT) is dependent on its 77-residue prosegment, which is then autocatalytically removed to give the mature enzyme. Mature subtilisin represents a class of proteins that lacks an efficient folding pathway. Refolding of mature SBT is extremely slow unless catalyzed by the independently expressed prosegment, leading to a bimolecular complex.

RESULTS

We report the crystal structure at 2.0 A resolution of the prosegment-SBT complex and consider its implications for prosubtilisin BPN' maturation and folding catalysis. The prosegment forms a compact domain that binds SBT through an extensive interface involving the enzyme's two parallel surface helices (residues 104-116 and 133-144), supplying negatively charged caps to the N termini of these helices. The prosegment C terminus binds in the enzyme active site in a product-like manner, with Tyr77 in the P1 binding pocket.

CONCLUSIONS

The structure of the complex supports a unimolecular mechanism for prosubtilisin cleavage, involving a 25 A rearrangement of the SBT N terminus in a late folding step. A mechanism of folding catalysis in which the two helices and their connecting beta strand form a prosegment-stabilized folding nucleus is proposed. While this putative nucleus is stabilized by prosegment binding, the N-terminal and C-terminal subdomains of SBT could fold by propagation.

Catalysis of a protein folding reaction: mechanistic implications of the 2.0 A structure of the subtilisin-prodomain complex

Biosynthesis of subtilisin is dependent on a 77 amino acid, N-terminal prodomain, which is autocatalytically processed to create the mature form of the enzyme [Ikemura, H., Takagi, H., & Inouye, M. (1987) J. Biol. Chem. 262, 7859-7864]. In order to better understand the role of the prodomain in subtilisin folding, we have determined the structure of the processed complex between the prodomain and subtilisin Sbt-70, a mutant engineered for facilitated folding. The prodomain is largely unstructured by itself but folds into a compact structure with a four-stranded antiparallel beta-sheet and two three-turn alpha-helices when complexed with subtilisin. The Ka of the complex is 2 x 10(8) M-1 at 25 degrees C. The prodomain binds on subtilisin's two parallel surface alpha-helices and supplies caps to the N-termini of the two helices. The C-terminal strand of the prodomain binds in the subtilisin substrate binding cleft. While Sbt-70 is capable of independent folding, the prodomain accelerates the process by a factor of > 10(7) M-1 of prodomain in 30 mM Tris-HCl, pH 7.5, at 25 degrees C. X-ray structures of the mutant subtilisin folded in vitro either with or without the prodomain are compared and show that the identical folded state is achieved in either case. A model of the folding reaction of Sbt-70 and the prodomain is described as the following equilibria: P + Su<-->Pf--SI<-->Pf--Sf, where Su and P are Sbt-70 and prodomain, respectively, which are largely unstructured at the start of the reaction, Pf--SI is a collision complex of a partially folded Sbt-70 and folded prodomain, and Pf--Sf is the complex of folded Sbt-70 and prodomain.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatoxin-a is a potent agonist of the nicotinic acetylcholine receptor of bovine adrenal chromaffin cells

(+)-Anatoxin-a is a neurotoxic alkaloid produced by the cyanobacterium Anabaena flos-aquae. In this study synthetic (+/-)-anatoxin-a was tested on isolated bovine adrenal chromaffin cells to determine its ability to evoke secretion of endogenous catecholamines through neuronal-type nicotinic receptor activation. Anatoxin-a was found to act as a potent agonist of the secretory response of chromaffin cells with an EC50 of 1-2 microM, compared with an EC50 of 4-5 microM for nicotine. The cells responded to anatoxin-a and nicotine with bell-shaped concentration-response curves consistent with desensitisation at concentrations of anatoxin-a greater than 5 microM and of nicotine greater than 20 microM. The secretion of catecholamines stimulated by anatoxin-a was completely inhibited in a non-competitive manner by the nicotinic antagonist mecamylamine with an IC50 of 0.4-0.5 microM. In the presence of depolarising concentrations of K+ (15 or 50 mM), anatoxin-a increased the secretion of catecholamines in a concentration-dependent manner up to the same maximum as that achieved by anatoxin-a alone. It is concluded that anatoxin-a acts as a potent and selective nicotinic agonist, capable of evoking secretion of endogenous catecholamines from chromaffin cells via their neuronal-type nicotinic receptor.

Stress and coping strategies in community psychiatric nurses: a Q-methodological study

With the development of the concept of community care there has been a significant expansion of the community psychiatric nurse (CPN) profession. The present study attempts to examine which aspects of their work CPNs currently find stressful. The study also examines the various strategies which CPNs feel to be useful in attempting to cope with such occupational stress. Forty-four CPNs in four health districts participated in this Q-methodological study which provided the opportunity for CPNs to construct their own concepts of stressors and coping strategies. The results obtained indicated that CPNs identified nine distinct areas of stress within their work, along with 12 distinct coping strategies which they considered useful in attempting to deal with such stress. The implications of these findings are discussed.

Purification of type 1 protein (serine/threonine) phosphatases by microcystin-Sepharose affinity chromatography

A microcystin (MC)-Sepharose column was prepared by addition of 2-aminoethanethiol to the alpha, beta-unsaturated carbonyl of the N-methyldehydroalanine residue of MC-LR, followed by reaction of the introduced amino group with N-hydroxysuccinimide-activated CH-Sepharose. The MC-Sepharose bound protein phosphatase-1 (PP1) with high capacity and purified human PP1 gamma in one step from E. coli extracts. It was also used to purify forms of PP1 bound to myofibrils from skeletal muscle. Two of these comprised PP1 complexed to N-terminal fragments of the M-subunit which enhance its myosin phosphatase activity, while the third comprised PP1 and an N-terminal fragment of the glycogen-binding (G)-subunit.

Two crystal structures of the B1 immunoglobulin-binding domain of streptococcal protein G and comparison with NMR

The structure of the 56-residue B1 immunoglobulin-binding domain from streptococcal protein G has been determined in two different crystal forms. The crystal structures were deduced by molecular replacement, based on the structure of the B2 domain (Brookhaven accession code 1PGX). Final R values are 0.174 and 0.198 for orthorhombic and trigonal forms, for diffraction data from 6.0 to 2.07 A and from 6 to 1.92 A, respectively. The orthorhombic crystals have an unusually high packing density for protein crystals, with Vm = 1.66 and a solvent content of 26%. The protein structure is found to be very similar (rms deviation 0.25 A for 56 C alpha's) in the two crystal forms, with an efficiently packed hydrophobic core between a four-stranded beta-sheet and a four-turn alpha-helix. The B1 domain has the same fold and general structure as the B2 domain (rms deviations 0.36 and 0.39 A), despite the six residue differences between them. The crystallographic models differ from NMR-derived models in several local regions, primarily in the loop involving residues 46-51; other significant variations are observed in the helix and in the structure of bound water. The primary crystal contact is the same in both crystal forms, involving both sheet edges to form extended beta-sheets throughout the crystals.

An engineered disulfide cross-link accelerates the refolding rate of calcium-free subtilisin by 850-fold

The mature form of subtilisin is an unusual example of a monomeric protein with a high kinetic barrier to folding and unfolding. Using site-directed mutagenesis of subtilisin BPN', we are attempting to determine the physical and energetic nature of the kinetic barrier. The high-affinity calcium-binding site A has been shown to create a large enthalpic barrier to unfolding. Removing the calcium-binding site A from subtilisin by deleting amino acids 75-83 greatly accelerates both unfolding and refolding reactions. Here a disulfide cross-link is introduced between residues 22 and 87 in delta 75-83 subtilisin. This was done to probe the conformational entropy of the transition state for folding. The 1.8-A X-ray structure of this mutant and the effects of the cross-link on the kinetics of unfolding and refolding are reported. Consistent with an expected loss of entropy of the unfolded protein due to the cross-link, the disulfide accelerates folding relative to the uncross-linked form. The magnitude of the acceleration of folding rate (700-850-fold at 25 degrees C) indicates that residues 22 and 87 are ordered in the transition state such that the disulfide does not affect its total entropy. Although early organization of structure around amino acids 22 and 87 greatly accelerates folding, we do not know whether the early folding of this region is a highly populated folding pathway in the absence of the cross-link. The slow step in the delta 75-83 subtilisin folding reaction may be forming initial structures capable of propagating the folding reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium-independent subtilisin by design

A version of subtilisin BPN' lacking the high affinity calcium site (site A) has been produced through genetic engineering methods, and its crystal structure refined at 1.8 A resolution. This protein and the corresponding version containing the calcium A site are described and compared. The deletion of residues 75-83 was made in the context of four site-specific replacements previously shown to stabilize subtilisin. The helix that in wild type is interrupted by the calcium binding loop, is continuous in the deletion mutant, with normal geometry. A few residues adjacent to the loop, principally those that were involved in calcium coordination, are repositioned and/or destabilized by the deletion. Because refolding is greatly facilitated by the absence of the Ca-loop, this protein offers a new vehicle for analysis and dissection of the folding reaction. This is among the largest internal changes to a protein to be described at atomic resolution.

(+)-Anatoxin-a is a potent agonist at neuronal nicotinic acetylcholine receptors

The effects of the nicotinic agonist (+)-anatoxin-a have been examined in four different preparations, representing at least two classes of neuronal nicotinic receptors. (+)-Anatoxin-a was most potent (EC50 = 48 nM) in stimulating 86Rb+ influx into M10 cells, which express the nicotinic receptor subtype comprising alpha 4 and beta 2 subunits. A presynaptic nicotinic receptor mediating acetylcholine release from hippocampal synaptosomes was similarly sensitive to (+)-anatoxin-a (EC50 = 140 nM). alpha-Bungarotoxin-sensitive neuronal nicotinic receptors, studied using patch-clamp recording techniques, required slightly higher concentrations of this alkaloid for activation: Nicotinic currents in hippocampal neurons were activated by (+)-anatoxin-a with an EC50 of 3.9 microM, whereas alpha 7 homooligomers reconstituted in Xenopus oocytes yielded an EC50 value of 0.58 microM for (+)-anatoxin-a. In these diverse preparations, (+)-anatoxin-a was between three and 50 times more potent than (-)-nicotine and approximately 20 times more potent than acetylcholine, making it the most efficacious nicotinic agonist thus far described.

Refined structure of the pyruvoyl-dependent histidine decarboxylase from Lactobacillus 30a

The crystal structure of the pyruvoyl-dependent histidine decarboxylase from Lactobacillus 30a has been refined to an R-value of 0.15 (for the 5.0 to 2.5 A resolution shell) and 0.17 (for the 10.0 to 2.5 A resolution shell). A description of the overall structure is presented, focusing on secondary structure and subunit association. The enzyme is a hexamer of alpha beta subunits. Separate alpha and beta-chains arise from an autocatalytic cleavage reaction between two serine residues, which results in the pyruvoyl cofactor. The central core of the alpha beta subunit is a beta-sandwich which consists of two face-to-face three-stranded antiparallel beta-sheets, flanked by alpha-helices on each side. The beta-sandwich creates a stable fold that allows conformational strain to be introduced across an internal cleavage region between the alpha and beta chains and places the pyruvoyl cofactor in a position for efficient electron withdrawal from the substrate. Three alpha beta subunits are related by a molecular three-fold symmetry axis to form a trimer whose interfaces have complementary surfaces and extensive molecular interactions. Each of the interfaces contains an active site and a solvent channel that leads from the active site to the exterior of the molecule. The trimers are related by a crystallographic two-fold symmetry axis to form the hexamer with an overall dumbbell shape. The interface between trimers has few molecular interactions.