INTERACTION OF BACILLUS ANTHRACIS EXOSPORIUM PROTEIN BCLA WITH COMPLEMENT FACTOR H AND SPORE PERSISTENCE IN THE LUNG

Anthrax outbreaks in the United States and Europe and its potential use as a bioweapon have made Bacillus anthracis an interest of study. Anthrax infections are caused by the entry of B. anthracis spores into the host via the respiratory system, the gastrointestinal tract, cuts or wounds in the skin, and injection. Among these four forms, inhalational anthrax has the highest lethality rate and persistence of spores in the lungs of animals following pulmonary exposure has been noted for decades. However, details or mechanisms of spore persistence were not known. In this study, we investigated spore persistence in a mouse model. The results suggest that B. anthracis spores have special properties that promote persistence in the lung, and that there may be multiple mechanisms contributing to spore persistence. Moreover, recent discoveries from our laboratory suggest that spores evolved a sophisticated mechanism to interact with the host complement system. The complement system is a crucial part of the host defense mechanism against foreign microorganisms. Knowledge of the specific interactions that occur between the complement system and B. anthracis was limited. Studies performed in our laboratory have suggested that spores of B. anthracis can target specific proteins, such as Factor H (fH) of the complement system. Spores of B. anthracis are enclosed by an exosporium, which consists of a basal layer surrounded by a nap of hair-like filaments. The major structural component of the filaments is called Bacillus collagen-like protein of anthracis (BclA), which comprises a central collagen-like region and a globular C-terminal domain. BclA is the first point of contact with the innate system of an infected host. In this study, we investigated the molecular details of BclA-fH interaction with respect to the specific binding mechanism and the functional significance of this interaction in a murine model of anthrax infection. We hypothesized that the recruitment of fH to the spore surface by BclA limits the extent of complement activation and promotes pathogen survival and persistence in the infected host. Findings from this study are significant to understanding how to treat post-exposure prophylaxis and improve our knowledge of spores with the host immune system.

Coping with advanced cancer: Caregivers and their patients

Background. Being diagnosed with advanced cancer may be one of the most difficult challenges a person faces. To help deal with advanced cancer, patients and caregivers lean towards the coping skills most familiar to them. Depending on the person, one’s coping may either help or perpetuate the problem. ^ Purpose. To identify predictors of negative coping skills among a group patients and caregivers, and to identify the predictors of prolonged grief among a group of providers, 6-months post loss. ^ Methods. Advanced cancer patients and caregivers were interviewed at the time of their enrollment (baseline) and caregivers were interviewed 6 months after the patient’s death (post-loss). Each participant was administered questionnaires regarding demographics, mental health disorders, mental health service use, coping methods, quality of life, and suicide attempts. Patients were asked about their treatment and diagnosis. Other patient-related information was obtained from medical charts. Moreover, caregivers were given an assessment regarding their alcohol and smoking history. ^ Results. Among White patients, positive coping skills were positively correlated with quality of life and negative coping skills were negatively correlated with quality of life. Gender, psychiatric disorders, suicidality, alcohol and smoking history, and treatment and diagnosis, were significantly related to negative coping skills; however this relationship only held for Hispanic patients. Gender and psychiatric disorders demonstrated predictive value for negative coping skills among all patients. On the other hand, psychiatric disorders, major depression, anxiety disorder, suicidality, and alcohol and smoking history, were not significant predictors of which caregivers experienced prolonged grief. ^ Conclusion. There was a significant relationship between quality of life and positive and negative coping skills of patients and negative coping skills for caregivers. Factors such as gender, psychiatric disorders, suicidality, alcohol and smoking history, and treatment and diagnosis demonstrated predictive value for negative coping skills in patients. ^

Simulation of Drosophila circadian oscillations, mutations, and light responses by a model with VRI, PDP-1, and CLK.

A model of Drosophila circadian rhythm generation was developed to represent feedback loops based on transcriptional regulation of per, Clk (dclock), Pdp-1, and vri (vrille). The model postulates that histone acetylation kinetics make transcriptional activation a nonlinear function of [CLK]. Such a nonlinearity is essential to simulate robust circadian oscillations of transcription in our model and in previous models. Simulations suggest that two positive feedback loops involving Clk are not essential for oscillations, because oscillations of [PER] were preserved when Clk, vri, or Pdp-1 expression was fixed. However, eliminating positive feedback by fixing vri expression altered the oscillation period. Eliminating the negative feedback loop in which PER represses per expression abolished oscillations. Simulations of per or Clk null mutations, of per overexpression, and of vri, Clk, or Pdp-1 heterozygous null mutations altered model behavior in ways similar to experimental data. The model simulated a photic phase-response curve resembling experimental curves, and oscillations entrained to simulated light-dark cycles. Temperature compensation of oscillation period could be simulated if temperature elevation slowed PER nuclear entry or PER phosphorylation. The model makes experimental predictions, some of which could be tested in transgenic Drosophila.

A model of the roles of essential kinases in the induction and expression of late long-term potentiation.

The induction of late long-term potentiation (L-LTP) involves complex interactions among second-messenger cascades. To gain insights into these interactions, a mathematical model was developed for L-LTP induction in the CA1 region of the hippocampus. The differential equation-based model represents actions of protein kinase A (PKA), MAP kinase (MAPK), and CaM kinase II (CAMKII) in the vicinity of the synapse, and activation of transcription by CaM kinase IV (CAMKIV) and MAPK. L-LTP is represented by increases in a synaptic weight. Simulations suggest that steep, supralinear stimulus-response relationships between stimuli (e.g., elevations in [Ca(2+)]) and kinase activation are essential for translating brief stimuli into long-lasting gene activation and synaptic weight increases. Convergence of multiple kinase activities to induce L-LTP helps to generate a threshold whereby the amount of L-LTP varies steeply with the number of brief (tetanic) electrical stimuli. The model simulates tetanic, -burst, pairing-induced, and chemical L-LTP, as well as L-LTP due to synaptic tagging. The model also simulates inhibition of L-LTP by inhibition of MAPK, CAMKII, PKA, or CAMKIV. The model predicts results of experiments to delineate mechanisms underlying L-LTP induction and expression. For example, the cAMP antagonist RpcAMPs, which inhibits L-LTP induction, is predicted to inhibit ERK activation. The model also appears useful to clarify similarities and differences between hippocampal L-LTP and long-term synaptic strengthening in other systems.

A reduced model clarifies the role of feedback loops and time delays in the Drosophila circadian oscillator.

Although several detailed models of molecular processes essential for circadian oscillations have been developed, their complexity makes intuitive understanding of the oscillation mechanism difficult. The goal of the present study was to reduce a previously developed, detailed model to a minimal representation of the transcriptional regulation essential for circadian rhythmicity in Drosophila. The reduced model contains only two differential equations, each with time delays. A negative feedback loop is included, in which PER protein represses per transcription by binding the dCLOCK transcription factor. A positive feedback loop is also included, in which dCLOCK indirectly enhances its own formation. The model simulated circadian oscillations, light entrainment, and a phase-response curve with qualitative similarities to experiment. Time delays were found to be essential for simulation of circadian oscillations with this model. To examine the robustness of the simplified model to fluctuations in molecule numbers, a stochastic variant was constructed. Robust circadian oscillations and entrainment to light pulses were simulated with fewer than 80 molecules of each gene product present on average. Circadian oscillations persisted when the positive feedback loop was removed. Moreover, elimination of positive feedback did not decrease the robustness of oscillations to stochastic fluctuations or to variations in parameter values. Such reduced models can aid understanding of the oscillation mechanisms in Drosophila and in other organisms in which feedback regulation of transcription may play an important role.

Characterization of the ebp(fm) pilus-encoding operon of Enterococcus faecium and its role in biofilm formation and virulence in a murine model of urinary tract infection.

We recently identified 15 genes encoding putative surface proteins with features of MSCRAMMs and/or pili in the Enterococcus faecium TX0016 (DO) genome, including four predicted pilus-encoding gene clusters; we also demonstrated that one of these, ebpABC(fm), is transcribed as an operon, that its putative major pilus subunit, EbpC(fm) (also called pilB), is polymerized into high molecular weight complexes, and that it is enriched among clinical E. faecium isolates. Here, we created a deletion of the ebpABC(fm) operon in an endocarditis-derived E. faecium strain (TX82) and showed, by a combination of whole-cell ELISA, flow cytometry, immunoblot and immunogold electron microscopy, that this deletion abolished EbpC(fm) expression and eliminated EbpC(fm)-containing pili from the cell surface. However, transcription of the downstream sortase, bps(fm), was not affected. Importantly, the ebpABC(fm) deletion resulted in significantly reduced biofilm formation (p < 0.0001) and initial adherence (p < 0.0001) versus the wild-type; both were restored by complementing ebpABC(fm) in trans, which also restored cell surface expression of EbpC(fm) and pilus production. Furthermore, the deletion mutant was significantly attenuated in two independent mixed infection mouse urinary tract experiments, i.e., outnumbered by the wild-type in kidneys (p = 0.0003 and < 0.0001, respectively) and urinary bladders (p = 0.0003 and = 0.002). In conclusion, we have shown that the ebpABC(fm) locus encodes pili on the E. faecium TX82 cell surface and provide the first evidence that pili of this emerging pathogen are important for its ability to form biofilm and to cause infection in an ascending UTI model.

Construct Validity of the Pig Intestine Model in the Simulation of Laparoscopic Urethrovesical Anastomosis

Introduction: Laparoscopic training models are increasingly important in urology to allow trainees to improve their laparoscopic skills prior to going to the operating room. For a training model to be valid, it must correlate with performance in a real case. The model must also discriminate between experienced and inexperienced subjects. [See PDF for complete abstract]

Cryo-EM model of the bullet-shaped vesicular stomatitis virus.

Vesicular stomatitis virus (VSV) is a bullet-shaped rhabdovirus and a model system of negative-strand RNA viruses. Through direct visualization by means of cryo-electron microscopy, we show that each virion contains two nested, left-handed helices: an outer helix of matrix protein M and an inner helix of nucleoprotein N and RNA. M has a hub domain with four contact sites that link to neighboring M and N subunits, providing rigidity by clamping adjacent turns of the nucleocapsid. Side-by-side interactions between neighboring N subunits are critical for the nucleocapsid to form a bullet shape, and structure-based mutagenesis results support this description. Together, our data suggest a mechanism of VSV assembly in which the nucleocapsid spirals from the tip to become the helical trunk, both subsequently framed and rigidified by the M layer.

CATCH across Texas: Building a model for the diffusion of effective school-based health promotion programs

The impact of health promotion programs is related to both program effectiveness and the extent to which the program is implemented among the target population. The purpose of this dissertation was to describe the development and evaluation of a school-based program diffusion intervention designed to increase the rate of dissemination and adoption of the Child and Adolescent Trial for Cardiovascular Health, or CATCH program (recently renamed the Coordinated Approach to Child Health). ^ The first study described the process by which schools across the state of Texas spontaneously began to adopt the CATCH program after it was tested and proven effective in a multi-site randomized efficacy trial. A survey of teachers and administrator representatives of all schools on record that purchased the CATCH program, but were not involved in the efficacy trial, was used to find out who brought CATCH into the schools, how they garnered support for its adoption, why they decided to adopt the program, and what was involved in deciding to adopt. ^ The second study described how the Intervention Mapping framework guided the planning, development and implementation of a program for the diffusion of CATCH. An iterative process was used to integrate theory, literature, the experience of project staff and data from the target population into a meaningful set of program determinants and performance objectives. Proximal program objectives were specified and translated into both media and interpersonal communication strategies for program diffusion. ^ The third study assessed the effectiveness of the diffusion program in a case-comparison design. Three of the twenty Education Service Center regions in Texas were chosen, selected based on similar demographic criteria, and were followed for adoption of the CATCH curriculum. One of these regions received the full media and interpersonal channel intervention; a second received a reduced media-only intervention, and a third received no intervention. Results suggested the use of the interpersonal channels with media follow-up is an effective means to facilitate program dissemination and adoption. The media-alone condition was not effective in facilitating program adoption. ^

Chimpanzee: A predictive model for the human cytochrome P450 3A subfamily

The human cytochrome P450 3A (CYP3A) subfamily is responsible for most of the metabolism of therapeutic drugs; however, an adequate in vivo model has yet to be discovered. This study begins with an investigation of a controversial topic surrounding the human CYP3As--estrogen regulation. A novel approach to this topic was used by defining expression in the estrogen-responsive endometrium. This study shows that estrogen down-regulates CYP3A4 expression in the endometrium. On the other hand, analogous studies showed an increase in CYP3A expression as age increases in liver tissue. Following the discussion of estrogen regulation, is an investigation of the cross-species relationships among all of the CYP3As was completed. The study compares isoforms from piscines, avians, rodents, canines, ovines, bovines, and primates. Using the traditional phylogenetic analyses and employing a novel approach using exon and intron lengths, the results show that only another primate could be the best animal model for analysis of the regulation of the expression of the human CYP3As. This analysis also demonstrated that the chimpanzee seems to be the best available human model. Moreover, the study showed the presence and similarities of one additional isoform in the chimpanzee genome that is absent in humans. Based on these results, initial characterization of the chimpanzee CYP3A subfamily was begun. While the human genome contains four isoforms--CYP3A4, CYP3A5, CYP3A7, and CYP3A43--the chimpanzee genome has five, the four previously mentioned and CYP3A67. Both species express CYP3A4, CYP3A5, and CYP3A43, but humans express CYP3A7 while chimpanzees express CYP3A67. In humans, CYP3A4 is expressed at higher levels than the other isoforms, but some chimpanzee individuals express CYP3A67 at higher levels than CYP3A4. Such a difference is expected to alter significantly the total CYP3A metabolism. On the other hand, any study considering individual isoforms would still constitute a valid method of study for the human CYP3A4, CYP3A5, and CYP3A43 isoforms. ^

High-resolution microarray analysis of chromosome 20q in human colon cancer metastasis model systems

Amplification of human chromosome 20q DNA is the most frequently occurring chromosomal abnormality detected in sporadic colorectal carcinomas and shows significant correlation with liver metastases. Through comprehensive high-resolution microarray comparative genomic hybridization and microarray gene expression profiling, we have characterized chromosome 20q amplicon genes associated with human colorectal cancer metastasis in two in vitro metastasis model systems. The results revealed increasing complexity of the 20q genomic profile from the primary tumor-derived cell lines to the lymph node and liver metastasis derived cell lines. Expression analysis of chromosome 20q revealed a subset of over expressed genes residing within the regions of genomic copy number gain in all the tumor cell lines, suggesting these are Chromosome 20q copy number responsive genes. Bases on their preferential expression levels in the model system cell lines and known biological function, four of the over expressed genes mapping to the common intervals of genomic copy gain were considered the most promising candidate colorectal metastasis-associated genes. Validation of genomic copy number and expression array data was carried out on these genes, with one gene, DNMT3B, standing out as expressed at a relatively higher levels in the metastasis-derived cell lines compared with their primary-derived counterparts in both the models systems analyzed. The data provide evidence for the role of chromosome 20q genes with low copy gain and elevated expression in the clonal evolution of metastatic cells and suggests that such genes may serve as early biomarkers of metastatic potential. The data also support the utility of the combined microarray comparative genomic hybridization and expression array analysis for identifying copy number responsive genes in areas of low DNA copy gain in cancer cells. ^

Community health workers: The critical link to sustainable, healthy societies in low-resource settings---A model for the Baylor Shoulder to Shoulder Foundation

Community health workers (CHWs) can serve as a bridge between healthcare providers and communities to positively impact social determinants of health and, thus, the overall health of the population. The potential to effect lasting change is particularly significant within resource-poor settings with limited access to formally trained health care providers such as the small, rural village of Santa Ana Intibucá, Honduras and surrounding areas—located on the geographically and politically isolated border of Honduras and El Salvador. The Baylor Shoulder to Shoulder Foundation (BSTS) works in conjunction with Santa Ana's volunteer health committee to bring a health brigade that has provided health care and public health projects to the area at least twice a year since 2001. They have also hired a full-time Honduran physician, a Honduran in-country administrative director, and built a clinic; yet, no community health worker program exists. This CHW program model is the response to a clear need for a CHW program within the area served by BSTS and presents a CHW program model specific to Santa Ana Intibucá and surrounding areas to be implemented by BSTS. Methods used to develop this model include reviewing the literature for recommendations from leading authorities as well as successfully implemented CHW programs in comparable regions. This information was incorporated into existing knowledge and materials currently being used in the area. Using the CHW model proposed here, each brigade, in conjunction with the communities served, can help develop new modules to respond to the specific health priorities of the region at that time, incorporating consistent modes of contact with the local physician and the CHWs to provide refresher courses, training in new topics of interest, and to be reminded of the importance of community health workers' role as the critical link to healthy societies. With cooperation, effort, and support, the brigade can continue to help integrate a sustainable CHW system in which communities may be able to maximize the care they receive while also learning to care for their own health and the future of their communities.^