Reconstructing cardiac electrical excitations from optical mapping recordings.

The reconstruction of electrical excitation patterns through the unobserved depth of the tissue is essential to realizing the potential of computational models in cardiac medicine. We have utilized experimental optical-mapping recordings of cardiac electrical excitation on the epicardial and endocardial surfaces of a canine ventricle as observations directing a local ensemble transform Kalman filter data assimilation scheme. We demonstrate that the inclusion of explicit information about the stimulation protocol can marginally improve the confidence of the ensemble reconstruction and the reliability of the assimilation over time. Likewise, we consider the efficacy of stochastic modeling additions to the assimilation scheme in the context of experimentally derived observation sets. Approximation error is addressed at both the observation and modeling stages through the uncertainty of observations and the specification of the model used in the assimilation ensemble. We find that perturbative modifications to the observations have marginal to deleterious effects on the accuracy and robustness of the state reconstruction. Furthermore, we find that incorporating additional information from the observations into the model itself (in the case of stimulus and stochastic currents) has a marginal improvement on the reconstruction accuracy over a fully autonomous model, while complicating the model itself and thus introducing potential for new types of model errors. That the inclusion of explicit modeling information has negligible to negative effects on the reconstruction implies the need for new avenues for optimization of data assimilation schemes applied to cardiac electrical excitation.

The Rat Genome Database (RGD) facilitates genomic and phenotypic data integration across multiple species for biomedical research.

Model organism research is essential for discovering the mechanisms of human diseases by defining biologically meaningful gene to disease relationships. The Rat Genome Database (RGD, ( https://rgd.mcw.edu )) is a cross-species knowledgebase and the premier online resource for rat genetic and physiologic data. This rich resource is enhanced by the inclusion and integration of comparative data for human and mouse, as well as other human disease models including chinchilla, dog, bonobo, pig, 13-lined ground squirrel, green monkey, and naked mole-rat. Functional information has been added to records via the assignment of annotations based on sequence similarity to human, rat, and mouse genes. RGD has also imported well-supported cross-species data from external resources. To enable use of these data, RGD has developed a robust infrastructure of standardized ontologies, data formats, and disease- and species-centric portals, complemented with a suite of innovative tools for discovery and analysis. Using examples of single-gene and polygenic human diseases, we illustrate how data from multiple species can help to identify or confirm a gene as involved in a disease and to identify model organisms that can be studied to understand the pathophysiology of a gene or pathway. The ultimate aim of this report is to demonstrate the utility of RGD not only as the core resource for the rat research community but also as a source of bioinformatic tools to support a wider audience, empowering the search for appropriate models for human afflictions.

Reconstructing three-dimensional reentrant cardiac electrical wave dynamics using data assimilation.

For many years, reentrant scroll waves have been predicted and studied as an underlying mechanism for cardiac arrhythmias using numerical techniques, and high-resolution mapping studies using fluorescence recordings from the surfaces of cardiac tissue preparations have confirmed the presence of visible spiral waves. However, assessing the three-dimensional dynamics of these reentrant waves using experimental techniques has been limited to verifying stable scroll-wave dynamics in relatively thin preparations. We propose a different approach to recovering the three-dimensional dynamics of reentrant waves in the heart. By applying techniques commonly used in weather forecasting, we combine dual-surface observations from a particular experiment with predictions from a numerical model to reconstruct the full three-dimensional time series of the experiment. Here, we use model-generated surrogate observations from a numerical experiment to evaluate the performance of the ensemble Kalman filter in reconstructing such time series for a discordant alternans state in one spatial dimension and for scroll waves in three dimensions. We show that our approach is able to recover time series of both observed and unobserved variables matching the truth. Where nearby observations are available, the error is reduced below the synthetic observation error, with a smaller reduction with increased distance from observations. Our findings demonstrate that state reconstruction for spatiotemporally complex cardiac electrical dynamics is possible and will lead naturally to applications using real experimental data.

Neuraxial labor analgesia in an obese parturient with influenza A H1N1.

We describe the use of epidural analgesia in a 39-year-old G2P1 parturient presenting at 38(+6) weeks estimated gestation with confirmed influenza A H1N1 and superimposed bilateral pneumonia. Although the patient had an uncomplicated intra- and post-partum course, little is known about the safety of performing neuraxial analgesia or anesthesia in patients with influenza. The prevalence of viremia and possible translocation of blood-borne virus to the central nervous system are discussed.

Structural integrity of enamel: experimental and modeling.

Tooth enamel is the hardest tissue in the human body and is directly responsible for dental function. Due to its non-regenerative nature, enamel is unable to heal and repair itself biologically after damage. We hypothesized that with its unique microstructure, enamel possesses excellent resistance to contact-induced damage, regardless of loading direction. By combining instrumented indentation tests with microstructural analysis, we report that enamel can absorb indentation energy through shear deformation within its protein layers between apatite crystallites. Moreover, a near-isotropic inelastic response was observed when we analyzed indentation data in directions either perpendicular or parallel to the path of enamel prisms. An "effective" crystal orientation angle, 33 degrees -34 degrees , was derived for enamel microstructure, independent of the loading direction. These findings will help guide the design of the nanostructural architecture of dental restorative materials.

Therapeutic touch is back.

Healing or therapeutic touch is nothing new; in fact, certain civilizations have been using it for ages. But more and more practitioners are viewing it as a complement to today's high-tech medical care. By integrating the use of therapeutic touch into their home and hospice settings, caregivers are benefitting patients and themselves.

Cross-cultural caring. Positive outcomes in Hawaii.

Cultural diversity in Hawaii affects all aspects of health, illness, and death and dying. Effective home care requires sensitivity to each patient's culture and a knowledge of how cultural differences can affect client outcomes.

Foster family care--a nurturing alternative to institutionalization.

Foster family care is a compassionate alternative to institutional care. By placing clients with families who open their hearts and share their lives, one agency in Maui promotes the true spirit of ohana, the spirit of family.

The third molar as a cause of deep space infections.

An 81-month review of patients with deep space infections attributed to third molars requiring hospital admission is presented. Thirty-one patients were identified, with males predominating 2:1 and mandibular third molars as an etiology predominating 15:1. All patients were aged 23 years or older. Most patients identified (24) had one or more medical problems or other risk factors, the most frequent of which was smoking (18). All patients developing postoperative infections (9) had complete or partial bone impactions and a preoperative diagnosis of pericoronitis.

An epidemiologic and anatomic survey of odontogenic infections.

An 81-month review of patients with infections of odontogenic origin admitted to the oral and maxillofacial surgery service at a county hospital and teaching facility in northeast Ohio is presented. Age, sex, race, etiology, pathogens isolated, admission temperature, and admission white blood cell count were identified and related to the anatomic space(s) encountered. Multispace and single-space infections occurred with equal distribution. In both the multispace and single-space infections, the submandibular and buccal spaces were most frequently involved. Males were affected with single-space infections twice as often as females. An equal distribution among sexes was found in multispace infections. The most common age range for all infections was 25 to 30 years. alpha-Hemolytic streptococci, Bacteroides melaninogenicus, and beta-hemolytic streptococci were the most frequently isolated pathogens. Third molars were the prevalent cause in both multispace and single-space infections that required hospital admission.

Estimation of nitrogen excretion based on abbreviated urinary collections in patients on continuous parenteral nutrition.

The physiologic response to stress can create a net loss of nitrogen, which is indicative of a catabolic state. Nitrogen balance has been demonstrated to be a useful clinical indicator of a patient's catabolic state and the effectiveness of parenteral nutrition, but requires an estimate of total urinary nitrogen excretion. The standard method for determining total urinary nitrogen excretion is 24-hour urinary urea nitrogen excretion. Unfortunately, the 24-hour urine collection is inconvenient, cumbersome, sometimes inaccurate, and induces a lag in response time to changes in therapy. Although shorter collection times have been proposed, the validity of shorter-timed determinations remains open to question. To evaluate the estimation of 24-hour urine urea excretion from shorter-timed determinations, the urinary urea nitrogen excretion of 4-, 8-, and 12-hour durations was regressed against the 24-hour collection in 56 critically ill adult patients. The 12-hour determination provided satisfactory estimates of the 24-hour nitrogen excretion, but the 4-hour and 8-hour determinations did not. Thus, two times the 12-hour urine urea nitrogen determination can be substituted for the 24-hour determination in calculating nitrogen balance. A 12-hour determination can provide a more rapid turnaround of biochemical analysis, allow more timely nutritional intervention, decrease nursing time, and reduce the frequency of inaccurate or lost specimens.

Care of the asthmatic oral and maxillofacial surgery patient.

It is estimated that asthma affects 6 to 9 million people in the United States. The nature of this disease makes it a special concern to the oral and maxillofacial surgeon. Appropriate management of the asthmatic patient with regard to anesthesia and surgical procedures of the oral and maxillofacial region is discussed.

Prediction: A six-year follow-up.

The prereading and reading performance of a group of 370 predominantly Hispanic, bilingual public school children was followed for six years. The aim of the study was to compare the factorial make-up and predictive validity of tests used in the current research with findings from a previous study. The early study had followed the children from the end of their kindergarten year until the end of second grade. For purposes of the present study a 13-test predictor battery was administered to the children at the beginning of their first-grade year. This battery included a number of measures used in the early study, among them a 5-test Screening Index developed in the course of that study. Records were obtained of the follow-up children's 2nd, 3rd, 4th, 5th, and 6th grade reading test scores. Factor analysis of the pool of 13 predictor tests showed a two-cluster battery structure. These clusters closely resembled two of the four factors defined in the early study. As used with the group of bilingual children, the Screening Index misclassified many of the failing readers, as well as others who went ahead to read at grade level. The Screening Index quite accurately identified, across grades, children who eventually read well. A number of predictor tests administered at beginning of first grade continued to show significant correlations with reading at all grade levels. The consistent contribution of the predictor tests with reading points to their continuing usefulness as a point of departure for assessing children's readiness to read.

Modified Paul-Mikulicz ileocolostomy.

Primary anastomosis can often be safely performed between the distal ileum and colon after emergent right colectomy. However, when this is not possible, we believe that this ileocolostomy procedure can be performed safely and offers an attractive alternative to ileostomy. It differs from the classic Paul-Mikulicz procedure in that a common channel is created at the initial operation using a stapling device. This obviates the inherent risks of blindly placing bulky spur clamps between the colon and ileum in the postoperative period. Using this technique, we have encountered no staple line leaks, fluid or electrolyte imbalance, or skin excoriation in the postoperative or follow-up period of 26 patients. All ileocolostomies were closed through the ileocolostomy site without formal laparotomy and without complications.

Central venous septic thrombosis managed by superior vena cava Greenfield filter and venous thrombectomy: a case report.

Operative management of a patient with septic thrombosis from Candida organisms of the subclavian and central veins is described. Diagnosis was suspected on the basis of positive blood and catheter tip cultures, indium-labeled leukocyte scan, and bilateral upper extremity phlebograms. Venous thrombectomy with a Fogarty catheter of the upper extremity central veins was performed after a superior vena cava Greenfield filter had been placed to prevent pulmonary embolism. The thrombus culture was positive for Candida albicans, and the reestablishment of vein patency in conjunction with amphotericin B therapy resulted in cure. This technique allows a definitive diagnosis of septic central thrombosis to be made and reestablishment of vein patency may also enhance antibiotic therapy.

Effects of coumadin on the resolution of canine venous thrombi.

Experimental thrombosis of the inferior vena cava was induced in 39 dogs to create a thrombus that could be embolized to a Greenfield filter for measurement of thrombolytic activity. In the series of 17 control animals, thrombus weight had decreased from 0.871 +/- 0.10 g to 0.477 +/- 0.08 g (P less than 0.05) at 2 weeks and from 0.884 +/- 0.097 g to 0.106 +/- 0.025 g (P less than 0.001) at 4 weeks representing 56 and 12%, respectively, of initial weight. In the series of 22 animals treated with coumadin, the resolution in thrombus weight was from 0.849 +/- 0.13 g to 0.171 +/- 0.14 g (P less than 0.02) at 2 weeks and from 1.031 +/- 0.34 g to 0.013 +/- 0.013 g (P less than 0.05) at 4 weeks representing 20 and 1%, respectively, of initial weight. These results show that in this model where venous flow is preserved around a trapped thrombus, lysis proceeds at a significant rate, yet can be accelerated by therapeutic levels of coumadin.

Effect of anticoagulation on the lysis of filter entrapped thromboembolism in dogs.

Resolution of thrombi entrapped in Greenfield vena caval filters is a primary mechanism for maintenance of caval patency with this device following an embolic event. In order to determine if anticoagulation is beneficial in this setting, thrombus was harvested from 65 mongrel dogs with infrarenal IVC thrombosis after phenolization. These thrombi were weighed and embolized into Greenfield filters placed above the renal veins. The infrarenal IVCs were then ligated and the animals allowed to recover. Beginning the first postoperative day, animals were given either oral coumadin daily to elevate the prothrombin time above 1.5 normal, subcutaneous heparin 500 u/kg/day divided into two doses, or received no treatment. They were sacrificed either 1, 2, 3, or 4 weeks after embolism and the residual thrombi weighed. Initial thrombus weights were similar for each period (differences NS). Comparison of initial with final weights revealed that both coumadin and heparin-treated animals had a significantly increased resolution in the first week when compared to controls. By 2 weeks, however, there were no significant differences between the groups, and controls proceeded to a mean of 95% resolution by 4 weeks. A general linear model used to separate the effects of treatment, time, and initial thrombus weight showed that resolution was primarily a function of initial thrombus weight, and of time. Coumadin was marginally beneficial. Thrombus resolution proceeds rapidly in this model without anticoagulation. These data suggest that prevention of deep vein thrombosis and its sequelae remain the sole indication for anticoagulation after filter placement.

Internal intussusception of the rectum. Diagnosis and surgical management.

Internal intussusception of the rectum is described as a specific clinical entity. A review of the cases treated at the Colon and Rectal Surgery Service at Jewish Hospital is presented, along with the specific diagnostic procedures that have been developed and the surgical technique that allows relatively simple correction of the problem. It is believed that this entity presents commonly to the practitioner of colon and rectal surgery, and specific diagnoses and therapy will be an important addition to the armamentarium of the colon and rectal surgeon.

Unsuspected right ventricular dysfunction in shock and sepsis.

Monitoring of ventricular function by central venous (CVP) and pulmonary wedge pressures (PCW) was compared with ejection fraction and end-diastolic volume (gated pool scan) in patients resuscitated from hypovolemic and septic shock. Sixteen patients were studied within 24 hours of resuscitation and all showed depressed right ventricular ejection (RVEF) and/or an increased end-diastolic volume (RVEDVI). Group I (eight patients, hypovolemia and sepsis) had low RVEF (mean, 0.30), high RVEDVI (mean 129.2 ml/m2), and nearly normal left ventricular function (LVEF 0.63 and LVEDVI 63.6 ml/m2), compared to angiographic normals (RVEF 0.52, RVEDVI 55.8 ml/m2; nL LVEF 0.59, LVEDVI 52.3 ml/m2). Group II (3 patients, all septic) had better RVEF (mean, 0.54) but high RVEDVI (mean, 121.1 ml/m2) with normal LVEF (mean, 0.67) and high LVEDVI (mean LVEDVI 107.2 ml/m2). Group III consisted of five patients (hypovolemia and sepsis) who had biventricular depression (RVEF 0.25 and LVEF 0.29) and elevated EDVI. The mortality rate for group I (25%) was significantly less than for groups II and III (100% and 80%, respectively), and could be correlated with failure to improve RV function. Follow-up studies in ten patients showed improvement in seven which correlated with increased RVEF and reduced RVEDVI. Comparing survivors to non-survivors showed no predictability on the basis of initial studies but a significantly larger RVEDVI and RV stroke work index in non-survivors' follow-up studies. No correlation could be made with left ventricular performance, and there were no correlations between PCWP and LVEDVI or CVP and RVEDVI. A significant negative correlation was seen between RVEF and pulmonary vascular resistance (r = -0.34, p less than 0.05). Both LVEDVI and RVEDVI were correlated significantly with cardiac index and with each other. RV dysfunction occurs after resuscitation of hypovolemia and sepsis without reliable alteration in filling pressure and is likely related to myocardial ischemia as well as increased pulmonary vascular resistance. Survival seems to depend on improvement in RV performance, which can be measured at the bedside by cardiac scintigraphy.