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B M Pinto

Publications and source records attributed to B M Pinto.

At least 55 records · Page 3Linked to original sources
PubMed1995

Transferred nuclear Overhauser enhancement experiments show that the monoclonal antibody strep 9 selects a local minimum conformation of a Streptococcus group A trisaccharide-hapten.

Transferred nuclear Overhauser enhancement (TRNOE) experiments have been performed to investigate the bound conformation of the trisaccharide repeating unit of the Streptococcus Group A cell-wall polysaccharide. Thus, the conformations of propyl 3-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-2-O-(alpha-L-rhamnopyran osyl)- alpha-L-rhamnopyranoside [C(A')B] (1) as a free ligand and when complexed to the monoclonal antibody Strep 9 were examined. Improved insights about the conformational preferences of the glycosidic linkages of the trisaccharide ligand showed that the free ligand populates various conformations in aqueous solution, thus displaying relatively flexible behavior. The NOE HNAc-H2A', which was not detected in previous work, accounts for a conformation at the beta-(1-->3) linkage with a phi angle of approximately 180 degrees. Observed TRNOEs for the complex are weak, and their analysis was further complicated by spin diffusion. With the use of transferred rotating-frame Overhauser enhancement (TRROE) experiments, the amount of spin diffusion was assessed experimentally, proving that all of the observed long-range TRNOEs arose through spin diffusion. Four interglycosidic distances, derived from the remaining TRNOEs and TRROEs, together with repulsive constraints, derived from the absence of TRROE effects, were used as input parameters in simulated annealing and molecular mechanics calculations to determine the bound conformation of the trisaccharide. Complexation by the antibody results in the selection of one defined conformation of the carbohydrate hapten. This bound conformation, which is a local energy minimum on the energy maps calculated for the trisaccharide ligand, shows only a change from a +gauche to a -gauche orientation at the psi angle of the alpha-(1-->2) linkage when compared to the global minimum conformation. The results infer that the bound conformation of the Streptococcus Group A cell-wall polysaccharide is different from its previously proposed solution structure (Kreis et al., 1995).

Antibodies, Monoclonal↗
PubMed1995

Synthesis of a thio analogue of n-propyl kojibioside, a potential glucosidase inhibitor.

The disaccharide alpha-D-Glc p-(1-S-2)-beta-D-Glc p-(1-OPr) 1, a thio analogue of alpha-D-Glc p-(1 --> 2)-alpha-D-Glc p-(1-OPr)(n-propyl kojibioside) in which the inter-glycosidic oxygen atom is replaced by sulfur, has been synthesized for evaluation as a potential glucosidase inhibitor. Glycosylation of the 2-thiol glucopyranosyl acceptor 4 with the trichloroacetimidate of 2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranose 5 gave the alpha-linked disaccharide 6 stereoselectively. Deprotection was performed by hydrogenolysis in the presence of Pd/C to give 1 as the beta-n-propyl glycoside. Glycosylation of the thiol 4 with the trichloroacetimidate of 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranose 8 gave a 1:2.3 mixture if the alpha and beta disaccharides (9 and 10); evidence is presented for the occurrence of the orthoester 11, as an intermediate in the formation of the beta-disaccharide.

Carbohydrate Sequence↗
PubMed1995

Application of two-dimensional NMR spectroscopy and molecular dynamics simulations to the conformational analysis of oligosaccharides corresponding to the cell-wall polysaccharide of Streptococcus group A.

This paper describes the use of a protocol for conformational analysis of oligosaccharide structures related to the cell-wall polysaccharide of Streptococcus group A. The polysaccharide features a branched structure with an L-rhamnopyranose (Rhap) backbone consisting of alternating alpha-(1-->2) and alpha-(1-->3) links and D-N-acetylglucosamine (GlcpNAc) residues beta-(1-->3)-connected to alternating rhamnose rings: [formula: see text] Oligomers consisting of three to six residues have been synthesized and nuclear magnetic resonance (NMR) assignments have been made. The protocol for conformational analysis of the solution structure of these oligosaccharides involves experimental and theoretical methods. Two-dimensional NMR spectroscopy methods (TOCSY, ROESY and NOESY) are utilized to obtain chemical shift data and proton-proton distances. These distances are used as constraints in 100 ps molecular dynamics simulations in water using QUANTA and CHARMm. In addition, the dynamics simulations are performed without constraints. ROE build-up curves are computed from the averaged structures of the molecular dynamics simulations using the CROSREL program and compared with the experimental curves. Thus, a refinement of the initial structure may be obtained. The alpha-(1-->2) and the beta-(1-->3) links are unambiguously defined by the observed ROE cross peaks between the A-B',A'-B and C-B,C'-B' residues, respectively. The branch-point of the trisaccharide CBA' is conformationally well-defined. Assignment of the conformation of the B-A linkage (alpha-(1-->3)) was problematic due to TOCSY relay, but could be solved by NOESY and T-ROESY techniques. A conformational model for the polysaccharide is proposed.

Carbohydrate Conformation↗
PubMed1995

A stages of change approach to understanding college students' physical activity.

This study examined self-reports of physical activity behavior among college students from a stages of change perspective. A questionnaire on health needs was administered to a random sample of 800 students at a private university; 217 completed questionnaires were analyzed, using chi-square statistics. In addition to examining activity behavior from a stages of change approach, the authors explored the relationship of demographic variables to activity behavior. Forty-six percent of the students were inactive or were exercising irregularly. Gender and year in school were unrelated to stage of exercise adoption. Results from this pilot study indicate the need for stage-matched interventions to increase activity levels in young adults.

Adult↗
PubMed1994

Stress, coping, and well-being among third-year medical students.

BACKGROUND: Medical school is recognized as a stressful environment that often exerts a negative effect on the academic performance, physical health, and psychological well-being of the student. METHOD: Stress, coping, depression, and somatic distress were examined among 69 third-year students completing a psychiatry clerkship in 1992-93 at the University of Mississippi School of Medicine. Stress was assessed using the Medical Education Hassles Scale-R. Coping was assessed using the Coping Strategies Inventory. Depression was assessed using the Center for Epidemiologic Studies-Depression Scale, and somatic distress was assessed using the Wahler Physical Symptoms Inventory. Statistical methods included correlational analysis and hierarchical regression. RESULTS: Clinical levels of depression were found in 16 (23%) of the students, and 39 (57%) endorsed high levels of somatic distress. Stress accounted for a large percentage of the distress variance (i.e., 29% to 50%). Coping efforts contributed significant variance to the prediction of distress above and beyond that accounted for by stress alone, especially in relation to depression. Coping efforts classified by Engagement strategies were associated with fever depressive symptoms, while coping efforts classified by Disengagement strategies were associated with higher levels of depressive symptoms. CONCLUSIONS: Because students who employed coping efforts characterized by Engagement strategies suffered from fewer depressive symptoms, the results suggest that training in these types of strategies may be a useful intervention to lessen the negative consequences of stress among medical students.

Adaptation, Psychological↗
PubMed1993

Convergent synthesis of an elusive hexasaccharide corresponding to the cell-wall polysaccharide of the beta-hemolytic Streptococcus group A.

A convergent synthesis of a hexasaccharide corresponding to the cell-wall polysaccharide of the beta-hemolytic Streptococcus Group A is described. The strategy relies on the preparation of a key linear trisaccharide unit beta-D-GlcpNAc-(1-->3)-alpha-L-Rhap-(1-->2)-alpha-L-Rhap which has previously resisted our efforts. The trisaccharide functions both as a glycosyl acceptor and donor to give an elusive hexasaccharide. This fully functionalized unit can serve, in turn, as a glycosyl acceptor or donor for the synthesis of higher-order structures. Deprotection gives a hitherto unknown hexasaccharide for use as a hapten in immunochemical studies. The characterization of all compounds by high-resolution 1H and 13C NMR spectroscopy is also described.

Carbohydrate Conformation↗
PubMed1993

Preliminary crystallographic analysis of a Fab specific for the O-antigen of Shigella flexneri cell surface lipopolysaccharide with and without bound saccharides.

The Fab of a monoclonal anti-carbohydrate antibody, SYA/J6 (IgG3, kappa, murine), raised against the O-polysaccharide antigen of the cell surface lipopolysaccharide of variant Y Shigella flexneri, a Gram negative bacterium, has been crystallized in the unliganded form and in complex with tri- and pentasaccharide antigens. The three crystal forms belong to the tetragonal space group P4(3)2(1)2, or P4(1)2(1)2, with very similar unit cell dimensions and an asymmetric unit that contains one molecule of about 50,000 Daltons, and a fourth crystal form belongs to monoclinic space group P2(1) that contains four molecules of Fab in an asymmetric unit. Whereas diffractions of these crystals on an area detector-rotating anode system extend to only about 3.5 A resolution, those measured using an imaging plate and synchrotron radiation at the Photon Factory facility extend to 2.5 A.

Antibodies, Monoclonal↗
PubMed1992

Immunochemical characterization of polyclonal and monoclonal Streptococcus group A antibodies by chemically defined glycoconjugates and synthetic oligosaccharides.

Synthetic oligosaccharides of increasing complexity that represent different epitopes of the Streptococcus Group A cell-wall polysaccharide were used as haptens and glycoconjugates of bovine serum albumin (BSA) and horse hemoglobin (HHb) to characterize polyclonal and monoclonal antibodies. Rabbits were immunized with the BSA glycoconjugates of a linear trisaccharide, branched trisaccharide, and branched pentasaccharide. The binding specificities of the polyclonal antisera were determined by a series of inhibition ELISA studies in which disaccharide through pentasaccharide haptens were used as inhibitors of antibody-glycoconjugate binding. Monoclonal antibodies derived from mice immunized with a killed bacterial vaccine were selected for their binding to native polysaccharide antigen coupled to BSA and the BSA glycoconjugates of the di- and linear tri-saccharides. Polyclonal antibodies were moderately specific for the oligosaccharide epitope of the immunizing glycoconjugate and only those antibodies raised to the branched pentasaccharide antigen showed cross-reaction with the bacterial antigen. The behaviour of selected monoclonal antibodies parallels the binding profile of polyclonal antibodies in that the two highest-titre antibodies were directed toward an epitope displayed by the branched pentasaccharide.

Animals↗
PubMed1992

Convergent synthesis of higher-order oligosaccharides corresponding to the cell-wall polysaccharide of the beta-hemolytic Streptococci group A. A branched hexasaccharide hapten.

A convergent synthesis of a hexasaccharide corresponding to the cell-wall polysaccharide of the beta-hemolytic Streptococci Group A is described. The strategy relies on the preparation of a key branched trisaccharide unit alpha-L-Rhap-(1----2)-[beta-D-GlcpNAc-(1----3)]-alpha-L-Rhap which functions both as a glycosyl acceptor and donor. The hexasaccharide is obtained after only three glycosylation reactions. This fully functionalized unit can serve, in turn, as a glycosyl acceptor or donor for the synthesis of higher-order structures. Deprotection gives a hexasaccharide for use as a hapten in immunochemical studies. The characterization of all compounds by high resolution 1H- and 13C-n.m.r. spectroscopy is also described.

Carbohydrate Sequence↗
PubMed1991

Synthesis and n.m.r. analysis of branched trisaccharide and pentasaccharide haptens of the beta-hemolytic streptococci group A and the preparation of synthetic antigens.

The synthesis of branched trisaccharide and pentasaccharide portions of the cell-wall polysaccharide of the beta-hemolytic Streptococci Group A is described. The key dissaccharide acceptors, allyl or 8-(methoxycarbonyl)ocytol 3-O-(3,4,6-tri-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl)-4-O -benzyl - alpha-L-rhamnopyranoside, in conjunction with a selectively blocked alpha-L-rhamnopyranosyl chloride under Koenigs-Knorr conditions, afforded the branched trisaccharides in 81 and 62% yield, respectively. Analogously, glycosylation of the 8-(methoxycarbonyl)octyl disaccharide with a protected beta-D-GlcpNAc-(1----3)-alpha-L-Rhap-(1----3)-alpha-L-Rhap chloride gave the pentasaccharide in 43% yield. The key disaccharide acceptors were obtained, in turn, from the allyl or 8-(methoxycarbonyl)octyl rhamnoside acceptors and 3,4,6-tri-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl chloride under Koenigs-Knorr conditions. The latter glycosyl donor has not been described previously. Removal of the protecting groups afforded the trisaccharide haptens as their 1-propyl and 8-(methoxycarbonyl)octyl glycosides and the pentasaccharide as its 8-(methoxycarbonyl)octyl glycoside. The compounds have been subjected to detailed analysis by two-dimensional n.m.r. methods. Preparation of the synthetic antigens followed coupling of the 8-(methoxycarbonyl)octyl glycosides to bovine serum albumin via the acyl azide intermediates.

Carbohydrate Sequence↗
PubMed1984

The conformation of Salmonella O-antigenic oligosaccharides of serogroups A, B, and D1 inferred from 1H- and 13C-nuclear magnetic resonance spectroscopy.

The conformational model derived by the HSEA calculation method was used to interpret the n.m.r. data for solutions of oligosaccharides corresponding to the Salmonella serogroups A, B, and D1 antigenic determinants. The favored conformer, derived by calculation, accounted for the observed, chemical-shift changes and accurately predicted the existence and magnitude of inter-ring proton n.O.e.'s. Extensive proton-density and compression of proton, Van der Waals radii were correlated with deshielding of specific proton-resonances. The model of lipopolysaccharide conformation accounts for the known antigenic properties of Salmonella O-antigens.

Carbohydrate Conformation↗
PubMedDate not supplied

Exercise in the rehabilitation of breast cancer survivors.

With the increase in the number of women who have survived breast cancer, there is a growing need to attend to the physical and emotional effects of cancer and its treatment as experienced by these survivors. Psychological distress, fatigue, weight gain, premature menopause and changes in body image are some of the long-term sequelae of breast cancer. Exercise as an adjunctive treatment may help to attenuate these effects and thereby contribute to rehabilitation of women with breast cancer. We present data from the exercise literature and from studies on breast cancer patients that support this role of exercise. Following a critique of the research efforts, we present a brief outline of questions that should be addressed in evaluating the role of exercise in cancer rehabilitation.

Body Image↗
PubMedDate not supplied

Cognitive-behavioral mediators of changing multiple behaviors: smoking and a sedentary lifestyle.

BACKGROUND: A significant percentage of the U.S. population has multiple poor health behaviors. Understanding the relationship among these behavioral risk factors is important for designing effective multiple risk factor interventions. While there is some evidence suggesting that participation in physical exercise may have a positive impact on smoking cessation, there is much to be learned about the relationships between cognitive-behavioral (self-efficacy, decisional-balance) and motivational mechanisms (stage of change) which have been shown to mediate changes in both exercise and smoking behavior. METHODS: The sample comprised 332 smokers employed at two workplaces-a government agency and a medical center-recruited as part of a larger worksite health promotion project and who completed questionnaires on their smoking and exercise behaviors. RESULTS: The results revealed significant relationships between smoking variables and exercise variables. Smokers who rated as important the positive benefits of smoking also rated as important the costs associated with increased physical activity. Similarly, the negative consequences of smoking were significantly associated with the positive benefits of physical activity. Self-efficacy for one behavior was significantly associated with self-efficacy for the other. Significant differences by exercise and smoking stage of change were found on the cross-behavior sets of variables (self-efficacy, pros, cons). Smokers who were contemplating a more active lifestyle reported the negative consequences of smoking to be significantly more important to them than smokers who were not considering adoption of a more active lifestyle. Smokers who were exercising regularly reported significantly more confidence in their ability to refrain from smoking than smokers not exercising regularly. Finally, smokers preparing for quitting reported less confidence in their ability to exercise than smokers who had already taken action to change their smoking behavior. CONCLUSIONS: The cognitive mechanisms associated with changes in smoking behavior are related to the cognitive variables which have been shown to predict changes in exercise behavior. Significant relationships in mediating mechanisms including decisional balance and self-efficacy between smoking and exercise provide preliminary information on how change in one risk behavior may relate to change in another. These associations have implications for future intervention research and for methods research on multiple risk factors interactions.

Adult↗
PubMedDate not supplied

Training physicians to conduct physical activity counseling.

BACKGROUND: In accordance with the U.S. Preventive Services Task Force recommendations, the current pilot study tests the feasibility and efficacy of a physician-delivered physical activity counseling intervention. METHODS: A sequential comparison group design was used to examine change in self-reported physical activity between experimental (counseling and self-help materials) and control (usual care) patients at base-line and 6 weeks after the initial office visit. Patients in both groups were contacted by telephone 2 weeks after their office visit and asked about the physical activity counseling at their most recent physician visit. Experimental patients also received a follow-up appointment to discuss physical activity with their physician 4 weeks after their initial visit. RESULTS: Counseling was feasible for physicians to do and produced short-term increases in physical activity levels. Both groups increased their physical activity, but the increase in physical activity was greater for patients who reported receiving a greater number of counseling messages. CONCLUSIONS: Physician-delivered physical activity interventions may be an effective way to achieve wide-spread improvements in the physical activity of middle-aged and older adults.

Aged↗
PubMedDate not supplied

Activity counseling by primary care physicians.

Modifying patients' sedentary lifestyle, a risk factor for many chronic diseases, is a challenge to health professionals. Although physicians can play a vital role in promoting physical activity among sedentary patients, the prevalence of physician-based exercise counseling is low. This paper presents a review of studies that have targeted physicians as agents of behavior change. Changing sedentary behavior is more likely to be effective when the intervention is grounded in theory. This paper outlines an integration of two theoretical models that have potential for enhancing behavior change, and it describes specific techniques for physicians interested in promoting a more active lifestyle among their patients.

Exercise↗