SIMUFLEX: Algorithms and Tools for Simulation of the Conformation and Dynamics of Flexible Molecules and Nanoparticles in Dilute Solution.

A computer programs suite, SIMUFLEX, has been constructed for the calculation of solution properties of flexible macromolecules modeled as bead-and-connector models of arbitrary topology. The suite consists mainly of two independent programs, BROWFLEX that generates the macromolecular trajectory by using the Brownian dynamics technique and ANAFLEX that analyzes that trajectory to get solution properties of the macromolecule. In this paper, we describe theoretical aspects about the macromolecular model and the Brownian dynamics algorithm used and describe some of the numerous properties that can be evaluated. In order to provide examples of the application of the methodology, we present simulations of dynamic properties of DNA with length ranging from 10 to 10(5) base pairs. SIMUFLEX is able to run simulations with more or less coarse-grained models, thus enabling such multiple-scale studies.

Sensitisation to Lepisma saccharina (silverfish) in children with respiratory allergy.

BACKGROUND: Lepisma saccharina (silverfish) is a common insect which is often found in human dwellings. Our aim was to determine the IgE antibody pattern to this arthropod in children with allergic respiratory symptoms. METHODS: The individual sera and a pool of selected sera of 45 children with asthma and/or rhinitis were used for an immunoblotting test with an extract of Lepisma saccharina; an immunoblotting inhibition test was performed with extracts of L. saccharina, D. pteronyssinus and cockroach. RESULTS: Between one and ten IgE binding bands were found in the sera of patients. The immunoblotting pattern was clearly different from that of D. pteronyssinus. Inhibition was found with D. pteronys-sinus and cockroach, which proves cross-reactivity between extracts. CONCLUSION: Allergenicity of Lepisma is demonstrated through in vitro tests. A pathogenic role still remains to be proved, but it should be considered in respiratory allergy, due to primary sensitisation to Lepisma, or to cross-reactivity with other indoor allergens.

Sensitisation to Lepisma saccharina (silverfish) in children with respiratory allergy

Background: Lepisma saccharina (silverfish) is a common insect which is often found in human dwellings. Our aim was to determine the IgE antibody pattern to this arthropod in children with allergic respiratory symptoms. Methods: The individual sera and a pool of selected sera of 45 children with asthma and/or rhinitis were used for an immunoblotting test with an extract of Lepisma saccharina; an immunoblotting inhibition test was performed with extracts of L. saccharina, D. pteronyssinus and cockroach. Results: Between one and ten IgE binding bands were found in the sera of patients. The immunoblotting pattern was clearly different from that of D. pteronyssinus. Inhibition was found with D. pteronyssinus and cockroach, which proves cross-reactivity between extracts. Conclusion: Allergenicity of Lepisma is demonstrated through in vitro tests. A pathogenic role stillre mains to be proved, but it should be considered inrespiratory allergy, due to primary sensitisation to Lepisma, or to cross-reactivity with other indoor allergens

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[Peculiarities of latex allergy and preventive measures in the pediatric age group]. / Peculiaridades de la alergia al látex y medidas preventivas en la edad pediátrica.

Latex allergy can be considered a problem of public health in at-risk populations. Although the figures on prevalence vary, approximately 1 % of the general population is sensitized to latex. To date, two determining factors for latex sensitization have been identified: an atopic predisposition and the number of operations. Among atopic patients or those at-risk for allergy, the prevalence of latex sensitization is between 3 and 20 times higher than that among the general population. Nevertheless, the effect of this factor seems to be modulatory and the determining factor seems to be the number of operations that children have undergone; the critical number is 5-6 interventions, after which the probability of sensitization increases considerably.All children who have undergone multiple operations should be considered as being at-risk. Children with spina bifida are especially at-risk. The reasons for this are still a matter of debate: the disease itself has been postulated as a specific risk factor, although other, possible associated factors could be determinant in triggering latex sensitization (the presence of a ventricular-peritoneal shunt, age at which surgery was performed, type of operation, etc.). Children with spina bifida and latex allergy show considerable differences in type of allergic sensitization; these differences seem to result from the different route of sensitization and could explain the variations observed in the clinical manifestations between children and adults: children become sensitized mainly by direct contact between latex particles and blood vessels and open mucosae while in adults the process takes place transcutaneously or by inhalation of aerosol particles. Consequently, the most frequent manifestation in children is urticaria while contact dermatitis and respiratory symptoms predominate in adults. Studies performed with immunoblotting have confirmed that children have IgE that almost constantly recognize low molecular weight latex proteins (14, 15 and 27 Kd) while this finding is less frequent in adults.The preventive measures in the pediatric population focus on avoidance of latex, especially in hospitals. Today, latex is ubiquitous, making complete avoidance difficult. When necessary, and whenever a latex-free environment cannot be guaranteed, presurgical medication can be used, although its utility is debatable. Although further studies are required, specific immunotherapy is one therapeutic possibility that may in future be used in children with latex allergy.

Peculiaridades de la alergia al látex y medidas preventivas en la edad pediátrica / Peculiarities of latex allergy and preventive measures in the pediatric age group

La alergia al látex puede considerarse un problema de salud pública en poblaciones de riesgo. Aunque las cifras de prevalencia son muy variables, se puede considerar que alrededor de un 1 % de la población general está sensibilizada a este material. Hasta la fecha se han identificado dos factores determinantes de la aparición de sensibilización a látex: la predisposición atópica y el número de intervenciones quirúrgicas. Entre pacientes atópicos o de riesgo alérgico, la prevalencia de sensibilización al látex es entre 3-20 veces superior a la de la población general. No obstante, este factor parece ejercer más bien un efecto modulador y el elemento más determinante lo constituye el número de operaciones a la que los niños son sometidos, estableciéndose en 5-6 el número crítico a partir del cual la probabilidad de sensibilización aumenta considerablemente. Todos los niños multioperados deben ser considerados como una población de riesgo. Entre ellos destacan especialmente los niños afectos de espina bífida. La explicación a este hecho constituye aún tema de debate: Se postula que la propia enfermedad podría constituir un factor específico en sí mismo, si bien existen posibles factores asociados que pueden ser determinantes a la hora de estimular el desarrollo de una sensibilización al látex (la presencia de válvula de derivación ventriculo peritoneal, la precocidad de las intervenciones, el tipo de éstas, etc). Los niños con espina bífida alérgicos al látex muestran importantes diferencias en el patrón de sensibilización alergénica respecto a pacientes adultos, las cuales parecen ser consecuencia de la diferente vía de sensibilización y podrían explicar las variaciones observadas en las manifestaciones clínicas que presentan unos y otros: los niños se sensibilizan, fundamentalmente, por contacto directo de partículas de látex con vasos sanguíneos y mucosas abiertas mientras que los adultos lo hacen por vía transcutánea, o por inhalación de partículas aerosolizadas. Consecuentemente, en los niños suele predominar la urticaria, mientras que en los adultos lo hacen la dermatitis de contacto y los cuadros respiratorios. En estudios realizados mediante immunoblottings se ha comprobado que los niños poseen IgE que reconoce de forma casi constante proteínas de látex de bajo PM (14, 15 y 27 kDa), mientras que en los adultos esto es más infrecuente. Las medidas preventivas a adoptar en población pediátrica se focalizan en todos los niveles de prevención, en la evitación de látex, de forma primordial en el ámbito hospitalario. El látex constituye hoy en día un material muy ubicuo, lo que dificulta una evitación total. En caso de necesidad y siempre que no pueda garantizarse un ambiente libre de látex, se puede recurrir a la medicación prequirúrgica, si bien su utilidad es discutible. Si bien se requieren más estudios, la inmunoterapia específica es una posibilidad terapéutica que podría utilizarse en un futuro en niños alérgicos a látex (AU)

Latex allergy can be considered a problem of public health in at-risk populations. Although the figures on prevalence vary, approximately 1 % of the general population is sensitized to latex. To date, two determining factors for latex sensitization have been identified: an atopic predisposition and the number of operations. Among atopic patients or those at-risk for allergy, the prevalence of latex sensitization is between 3 and 20 times higher than that among the general population. Nevertheless, the effect of this factor seems to be modulatory and the determining factor seems to be the number of operations that children have undergone; the critical number is 5-6 interventions, after which the probability of sensitization increases considerably. All children who have undergone multiple operations should be considered as being at-risk. Children with spina bifida are especially at-risk. The reasons for this are still a matter of debate: the disease itself has been postulated as a specific risk factor, although other, possible associated factors could be determinant in triggering latex sensitization (the presence of a ventricular-peritoneal shunt, age at which surgery was performed, type of operation, etc.). Children with spina bifida and latex allergy show considerable differences in type of allergic sensitization; these differences seem to result from the different route of sensitization and could explain the variations observed in the clinical manifestations between children and adults: children become sensitized mainly by direct contact between latex particles and blood vessels and open mucosae while in adults the process takes place transcutaneously or by inhalation of aerosol particles. Consequently, the most frequent manifestation in children is urticaria while contact dermatitis and respiratory symptoms predominate in adults. Studies performed with immunoblotting have confirmed that children have IgE that almost constantly recognize low molecular weight latex proteins (14, 15 and 27 Kd) while this finding is less frequent in adults. The preventive measures in the pediatric population focus on avoidance of latex, especially in hospitals. Today, latex is ubiquitous, making complete avoidance difficult. When necessary, and whenever a latex-free environment cannot be guaranteed, presurgical medication can be used, although its utility is debatable. Although further studies are required, specific immunotherapy is one therapeutic possibility that may in future be used in children with latex allergy (AU)

Adult constipation: a review and clinical guide.

Constipation is a common complaint that can be a symptom of serious disease. Awareness of the potential etiologies can help direct the history, physical exam and subsequent work-up for the presenting individual. This article details the differential diagnosis and pathophysiology of constipation based on a review of the literature. The article is also designed to be useful as a guide to the work-up of constipation. Key elements of the history, physical exam and testing are outlined. Included is a detailed flow diagram to guide the work-up of constipation. Testing methods and their value in the evaluation of chronic idiopathic constipation are discussed. Finally, although the focus of this article is the evaluation of constipation, a section on the treatment of constipation is included.

Colorectal cancer: update on recent advances and their impact on screening protocols.

As the third leading cause of cancer cases and deaths in the United States, colorectal cancer has been an area of intense interest. The objectives of this article are, through a review of the literature published between 1995 to 1998, to examine current trends in the epidemiology of colorectal cancer, new information on genetic, dietary, and other risk factors; to evaluate the effectiveness of current screening guidelines for various populations; to review information on chemoprevention; and finally to examine new concepts on the horizon in the area of colorectal cancer research. Much of the recent research in the field has focused on etiology, dietary, and other risk factors. Many genetic factors have been discovered, which serve to elucidate the mechanism of pathogenesis of colorectal cancer as well as offer possible targets for treatment strategies. Dietary and risk factors for colorectal cancer may pave the way for chemoprevention. In light of the most recent information on colorectal cancer, one is able to more accurately assess current screening guidelines for their effectiveness in all populations based on epidemiologic data, as well as evaluate more novel screening strategies for their possible utility in the future. In addition to a review of the most up-to-date literature, the authors also provide their recommendations for screening based on the evidence in which the review of the literature provides. Finally, current and future treatment options are discussed. It is our hope that the physicians will find this review useful in the evaluation and care of patients at risk of developing colorectal cancer.

Immunologic response to different determinants of benzylpenicillin, amoxicillin, and ampicillin. Comparison between urticaria and anaphylactic shock.

BACKGROUND: Subjects with IgE-mediated allergic reactions to penicillins can develop urticaria or anaphylactic shock. Urticaria is mainly associated with positivity to the major determinant of benzylpenicillin (BPO), and anaphylactic shock with minor determinants (MDM). The presence of IgG antibodies to BPO is thought to be mainly associated with urticaria, possibly protecting from anaphylactic shock. We aimed to study the skin test response to BPO and MDM, amoxicillin (AX), and ampicillin (AMP) in a group of subjects allergic to penicillins, and to evaluate the role of specific IgG. METHODS: We studied a group of patients with immediate allergic reactions to penicillins, comparing urticaria and anaphylactic shock. Skin tests were done with BPO, MDM, AX, and AMP. Specific IgE and IgG antibodies to benzylpenicilloyl-poly-L-lysine (BPO-PLL) and amoxicilloyl-poly-L-lysine (AXO-PLL) were determined by RAST and ELISA, respectively. RESULTS: Fifty-nine patients were studied (30 with anaphylactic shock and 29 with urticaria). Skin test positivity to BPO was associated with urticaria (P<0.001), and positivity to MDM, AX, and AMP with anaphylactic shock (P=0.006, P<0.001, and P=0.002, respectively). Specific anti-BPO-PLL and AXO-PLL IgG values were higher in patients than controls (P<0.001), but no differences were observed between urticaria and anaphylactic shock. CONCLUSIONS: Positivity to minor determinants of penicillins is associated more with anaphylactic shock than urticaria, but the role of IgG antibodies in helping to prevent the development of anaphylactic shock could not be confirmed.

Tumor markers. An update.

Cancer remains the second leading cause of death in developed countries, and the incidence of certain tumors is increasing despite emphasis on prevention and screening. Tumor markers are biologic or biochemical substances that are produced by tumor cells and then secreted into the circulation in detectable amounts. This article covers some of the more common tumor markers currently being utilized for diagnostic and prognostic purposes.

Colorectal cancer. A practical review for the primary care physician.

Colorectal cancer is a common disease in the United States. In the past 30 years, only limited improvements in stage of disease at the time of diagnosis and survival rates have been made. Research into genetic, environmental, and diet-related risk factors is promising but insufficient to serve as a foundation for preventive advice. The slowly progressive adenoma-carcinoma sequence is now commonly accepted. The American Cancer Society, Atlanta, Ga, and the National Cancer Institute, Bethesda, Md, advocate screening with annual fecal occult blood testing plus sigmoidoscopy every 3 to 5 years in persons 50 years old and older. The development of more cost-effective screening strategies is under study, with emphasis on targeting high-risk populations, determining optimal screening intervals, identifying the length of colon to study and by what means, and determining the surveillance needed in individuals who have had polyps removed.

Does early clinical exposure enhance performance during third-year clerkship?

This study was undertaken to assess the effects of early clinical exposure in an indigent care free clinic on third-year clerkship mini-board scores (clinical knowledge), faculty evaluation (especially rapport with colleagues and patients), and final rotation grades. After completion of third-year clerkships, a sample of participants was compared with nonparticipants. Comparative statistics, repeated measure analysis, and analyses of variance were performed on the entire group as well as by sex and by individual rotation. No statistically significant differences were found in the mainframe, but subgroup findings indicate further study is warranted. Negative findings might be explained in part by small sample size and the fact that the clinic is exclusively outpatient, while the third-year clerkship experience is inpatient. Data collection is being continued, and studies are ongoing to look at the long-term effect of the program on participants.

Biliary extracorporeal shock-wave lithotripsy: an update.

Since the mid-1980s, numerous clinical studies, involving hundreds of patients, have attested to the safety and efficacy of this technique. There have been no deaths, and occasional soft tissue damage appears to be temporary.

The effects of certain student and institutional characteristics on minority medical student specialty choice.

This article investigates the possible effects of minority status, presence of a Minority Affairs Office or Student National Medical Association (SNMA) Chapter, level of indebtedness, and number of years (4 to 5) to complete medical school on specialty choice of minority medical students. The 5-year experiences of 20 medical schools in the southern region (including three in Puerto Rico) were examined via a questionnaire. Information was sought for African Americans, Afro-Caribbean, Mexican American, other minority, and nonminority students. Minority graduates entered the specialities of internal medicine, pediatrics, and family medicine in far greater numbers than any other speciality. Also, the percentage of minorities who entered these fields was greater than the percentage of non-minorities. Conversely, minorities were significantly underrepresented in the surgical subspecialties and radiology. Additional study is needed to further examine the medical school experience for indications of why the clustering in primary care specialities occurs. Moreover, while most schools had some kind of minority affairs organization, few were active in the writing of the Dean's letter. Other suggestions to assure adequate minority representation across specialties include early exposure to the different specialties and subspecialties for minority students, a mentorship program with practicing physicians, and stronger recruitment of minorities into underrepresented specialties.

Seasonality of Chlamydia trachomatis genital infections in university women.

Previous studies have shown seasonal fluctuations in the incidence of most sexually transmitted diseases, with a peak in the third quarter, but none have specifically evaluated Chlamydia trachomatis genital infections. From 1989 to 1991, 8,234 women presenting to the student health centers of Florida's two largest universities for routine gynecologic care and diagnosis of sexually transmitted diseases were tested for Chlamydia trachomatis genital infections. The bimonthly variation in incidence was statistically significant, with a significant peak in the months of August and September of 10.70%, compared with the yearly average of 8.74%. Because the pattern of incidence of chlamydia in university women is seasonal, those concerned with healthcare should increase their efforts during the third quarter to identify infected individuals and to provide preventive programs.

Carcinoma of the trachea: a hidden tumor.

Seventy-five percent or more of the tracheal lumen may be compressed before any signs or symptoms are evident. Typically, chest x-rays are normal. CT scanning is the best radiologic procedure; bronchoscopy is also valuable.

Methanol intoxication. Case report.

A 46-year-old male presented to the emergency room seven hours after consuming a large container of sterno. He could not see and complained of abdominal and back pain. He was tachypneic, tachycardic, hypertensive and hypothermic. Laboratory results were significant for a severe metabolic acidosis, a serum osmolality of 465 and serum methanol level of 493 mg/dl. Aggressive treatment included ethanol drip, bicarbonate and hemodialysis. He survived and regained his eyesight in spite of this degree of elevation of the serum methanol level. The literature does not reveal a similar report.

Methanol intoxication. How to help patients who have been exposed to toxic solvents.

Methanol intoxication can be a challenge, in part because it is relatively uncommon but also because of the pharmacokinetics involved. A patient may not experience symptoms and thus may not present for treatment for several hours, or even a day or two, after exposure to the toxic substance. Yet, the interval between ingestion and treatment is one of the most important factors in determining patient outcome. Typical symptoms of methanol intoxication include lethargy, vertigo, vomiting, blurred vision, and decreased visual acuity. Treatment focuses on prevention of methanol conversion to its toxic metabolites, correction of metabolic acidosis, and elimination of the toxic substances from the system. Ethanol and bicarbonate administration and hemodialysis have been effective.

Lobular carcinoma in situ: what clinicians need to know.

The essential point is that LCIS cells are not likely to progress to invasive cancer. Rather, they represent breast tissue that is predisposed to cancer. Management thus emphasizes close follow-up.

Influence of longitudinal primary care training on medical students' specialty choices.

BACKGROUND: At the University of South Florida College of Medicine, a program designed to give students four years of primary care training began in 1983. As of 1992, six classes that included program participants had graduated. The present study examined the effect of the program on the participants' choices of specialty by comparing their choices with those of other graduates. METHOD: Each year program volunteers were solicited from a class size of about 96 freshmen. Of the 201 volunteers from the classes of 1987-1992, 93 were randomly selected to participate in the program. The participants received primary care education one half-day per week in a community-based clinical setting. The specialty choices of the 543 graduates from 1987-1992 were determined from the National Resident Matching Program and were divided into primary care (family practice, internal medicine, pediatrics); surgery, obstetrics-gynecology, and psychiatry; and other (high-technology specialties). Comparisons were made (1) between volunteers and nonvolunteers and (2) between volunteers who were participants and those who were not. The Z-test was used, with alpha set at .01. RESULTS: Significantly more volunteers--with no difference between participants and nonparticipants--matched with primary care specialties, and more volunteers were women. Significantly more nonvolunteers matched with high-technology specialties--again, no difference between participants and nonparticipants. CONCLUSION: The program did not seem to influence the students' specialty choices, because students interested in participating--regardless of whether they actually participated--were more likely to match with primary care specialties and were more likely to be women.