Immunoelectrochemical assays for bacteria: use of epifluorescence microscopy and rapid-scan electrochemical techniques in development of an assay for Salmonella.

Immunoelectrochemical sensors in which the sensor surface functions as both analyte capture phase and electrochemical detector have recently been developed for bacteria analysis. The speed and sensitivity of these devices make them very attractive for applications such as the detection of pathogenic microorganisms in food and water. However, the development and optimization of assays utilizing these sensors can be complicated by undesired interactions between the capture and detection functions. Modification of the sensor to achieve improvements in one function can have deleterious effects on the other function, and such effects can be difficult to diagnose and correct. In the course of investigations on immunoelectrochemical detection of Salmonella, we developed a rapid, nondestructive epifluorescence microscopy method to determine bacteria capture efficiency. This method enabled us to study capture and detection functions independently and efficiently identify performance-limiting factors. Rapid-scan electrochemical methods were used to optimize detection sensitivity and to provide diagnostic information on detection performance.

Growth profiles and articular cartilage characterization in a goat model of Legg-Calve-Perthes disease.

Numerous animal species, including the goat, have been evaluated as potential models for human Legg-Calve-Perthes disease (LCPD). These models disrupt the vasculature of the femoral head, causing it to collapse, and therefore do not mimic all the clinical patterns of the human disease. Baseline data regarding the weight and femoral length in the growing goat are not available. This study characterized the goat's normal growth for comparison with that of humans. The growth aberrations in the proximal femur created by surgically ablating the capital physis were described and compared with the aberrations observed in human LCPD cases. Age, weight, and femoral length (test and control) data were obtained for goats approximately 1 to 14 months of age. At 4 months of age, a craniolateral surgical approach was used to expose the cranial lateral capital physis so that it could be cauterized. Postoperative radiographs were evaluated by graphic analysis to assess the resultant changes in the morphology of the proximal femur. The articular cartilage of the femoral head and acetabulum was evaluated mechanically, using indentation testing, to determine the apparent modulus of elasticity, and histopathologically regarding its thickness and proteoglycan content. The proximal femurs of goats and humans exhibit similar morphology and growth patterns. There was a positive correlation between age, weight, and femoral lengths in the goat. The surgical procedure was effective in ablating the capital femoral physis as indicated by shorter femoral lengths and fragmented, flattened, and mushroomed femoral heads. The histopathological data revealed that the articular cartilage was significantly thicker in the operated hip joints at the ventrocaudal and cranial acetabula and the dorsal and ventral femoral heads. The test cartilage exhibited significantly less positive staining for proteoglycans in the dorsocaudal and the cranial acetabula as well as the ventral femoral head. The apparent modulus of elasticity, of the test cartilage was significantly lower than the control value at the dorsocaudal acetabulum. These data show that the surgical procedure produced morphological changes that mimic those in human LCPD. The increased thickness of the articular cartilage of the LCPD femoral head may account for the articular degeneration observed in older patients with LCPD, as increased cartilage thickness is associated with decreased tissue quality.

Data verification in the residue laboratory.

Residue analysis frequently presents a challenge to the quality assurance (QA) auditor due to the sheer volume of data to be audited. In the face of multiple boxes of raw data, some process must be defined that assures the scientist and the QA auditor of the quality and integrity of the data. A program that ensures that complete and appropriate verification of data before it reaches the Quality Assurance Unit (QAU) is presented. The "Guidelines for Peer Review of Data" were formulated by the Residue Analysis Business Center at Ricerca, Inc. to accommodate efficient use of review time and to define any uncertainties concerning what are acceptable data. The core of this program centers around five elements: Study initiation (definitional) meetings, calculations, verification, approval, and the use of a verification checklist.

The immature goat as an animal model for Legg-Calvé-Perthes disease.

Legg-Calvé-Perthes disease (LCPD) results from avascular necrosis of the capital femoral epiphysis in growing children. This disease often yields a significant deformity of the proximal femur, which may result in osteoarthritis. Its cause is unknown, although extensive radiographic, clinical, and histologic evaluations have been performed. Attempts at developing an animal model for LCPD have been unsuccessful. Previous models have been based predominantly on determining the vascular etiology of the disease. There is a need for an animal model that mimics the growth pattern of the proximal femur seen in LCPD. Such a model would allow for the development and testing of new treatments. Thus far, no treatment strategy has been completely successful. A study involving graphic analysis of radiographs found that arrested anterolateral physeal growth with continued or accelerated perichondrial ring and posteromedial epiphyseal growth would account for the most severe morphologic changes observed in the femoral heads of patients with LCPD. A surgical procedure was performed to ablate the capital femoral physis in goat kids in an attempt to mimic the changes noted in this study. The procedure was evaluated with radiographs, gross specimens, and histopathologic slides. Graphic analysis of the radiographs revealed changes in the shape of the operated femoral head compared with the unoperated femoral head. While bone, fibrous, and fibrocartilaginous bridges were histologically observed across the physis, the resultant deformities did not mimic the changes identified in the graphic analysis study, perhaps because of inconsistencies in the surgical ablative techniques, which will require further modification. This study provides the basis for further research to develop a successful model.

Reliability of echocardiography in the diagnosis of anomalous origin of the left coronary artery from the pulmonary trunk.

Previous studies have indicated that the definitive diagnosis of anomalous origin of the left coronary artery from the pulmonary trunk (ALC) should be made by cardiac catheterization and angiography. This study evaluates echocardiography (two-dimensional, pulsed Doppler, and color flow mapping) as a method to establish the diagnosis of ALC. To diagnose ALC, a modified parasternal short-axis view was used to demonstrate continuity of the ALC with the pulmonary trunk and to detect the retrograde flow through the ALC into the pulmonary trunk. Absence of these imaging characteristics ruled out ALC. From June 1985 to January 1990, 16 patients who presented with or had previously had a dilated poorly contracting left ventricle were prospectively assessed by echocardiography to rule out ALC. Four patients had ALC (age 2 to 120 months, mean +/- 1SD = 32 +/- 59) and 12 patients (age 1 to 192 months, mean +/- 1SD = 57 +/- 80) had myocardiopathy. Two other patients with known ALC were evaluated by an observer unaware of the diagnosis. All coronary anatomy was confirmed by angiography, surgery, or autopsy. The correct diagnosis of coronary anatomy was obtained by echocardiography in all instances without false positive or false negative diagnosis of ALC. Three infants underwent surgical repair of ALC based only on the echocardiographic diagnosis. Echocardiography can be used to establish the diagnosis of ALC. Therefore surgical repair can be undertaken in some critically sick infants based on the echocardiographic diagnosis alone.