Biocompatibility studies of the Anaconda stent-graft and observations of nitinol corrosion resistance.

PURPOSE: To validate the deployment, in vivo performance, biostability, and healing capacity of the Anaconda self-expanding endoprosthesis in a canine aortic aneurysm model. METHODS: Aneurysms were surgically created in 12 dogs by sewing a woven polyester patch onto the anterior side of the thoracic or abdominal aorta. Anaconda prostheses were implanted transfemorally for prescheduled periods (1 or 3 months). Aneurysm exclusion and stent-graft patency were monitored angiographically. Healing was assessed with histological analysis and scanning electron microscopy (SEM). Textile analysis determined the physical and chemical stability of the woven polyester material, while the biostability of the nitinol wires was evaluated with SEM and spectroscopy. RESULTS: All prostheses were intact at explantation. After 1 month, endothelial-like cells were migrating in a discontinuous manner both proximally and distally over the internal collagenous pannus at the device-host boundary. After 3 months, endothelialization had reached the midsections of the devices, with a thicker collagenous internal capsule. Patches of endothelial-like cells were sharing the luminal surface with thrombotic deposits. However, the wall of the device at the level of the aneurysm was generally poorly healed, with multiple thrombi scattered irregularly over the luminal surface. The polyester fabric was intact except for some filaments that were ruptured adjacent to the sutures and some abrasion caused by the nitinol wires. No evidence of corrosion was found on the nitinol stents. CONCLUSIONS: This Anaconda stent-graft has demonstrated its ability to exclude arterial aneurysms. The device used in this study was an experimental prototype, and the manufacturer has incorporated new immobilization features into the model for clinical use. The constituent materials appear to be suitable in terms of biocompatibility, biofunctionality, and short-term durability.     

Aspergillosis in a 24-week newborn: a case report.

Aspergillosis is an uncommon neonatal infection, diagnosed with an increasing frequency over the last two decades. We report a premature neonate who developed aspergillosis while receiving amphotericin B and fluconazole for candidiasis. Despite early recognition and diagnosis, the infant died. We review the clinical appearance of Aspergillus species, the distinctions between primary cutaneous aspergillosis and invasive aspergillosis, and advances in diagnosis and treatment.     

New approaches to QSAR: Neural networks and machine learning

Summary Neural networks and machine learning are two methods that are increasingly being used to model QSARs. They make few statistical assumptions and are nonlinear and nonparametric. We describe back-propagation from the field of neural networks, and GOLEM from machine learning, and illustrate their learning mechanisms using a simple expository problem. Back-propagation and GOLEM are then compared with multiple linear regression (using the parameters and their squares) on two real drug design problems: the inhibition ofEscherichia coli dihydrofolate reductase (DHFR) by pyrimidines and the inhibition of rat/mouse tumour DHFR by triazines.     

Effect of hepatic artery chemotherapy on survival of patients with hepatic metastases from colorectal carcinoma treated with cryotherapy

Thirty-eight patients with unresectable multiple liver metastases from colorectal carcinoma were treated with either hepatic artery chemotherapy (HAC) and cryotherapy (n=27) or cryotherapy alone (n=11). Follow-up survival data were summarized using Cox regression. Allowing for the effect of the pathology of the primary tumor and the preoperative carcinoembryonic antigen (CEA) level, those patients who did not receive HAC after cytoreduction were three times as likely to die as those given HAC (RR 3.3, 95%; CI 1.2–9.3). The estimated median survival of patients treated with cryotherapy alone was 245 days, whereas for those given more than 3 months of HAC plus cytoreduction therapy it was 570 days. It is recommended that all patients who receive cryotherapy for multiple liver metastases from colorectal rectal carcinoma be given subsequent hepatic artery chemotherapy.

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Resumen En el presente estudio, 38 pacientes con metástasis hepáticas múltiples y no resecables de carcinoma colo-rectal fueron tratados con quimioterapia administrada en la arteria hepática (HAC) y crioterapia (n=27) o crioterapia sola (n=11). Los datos del seguimiento fueron resumidos según el método de regresión de Cox. Teniendo en cuenta el efecto de la patología del tumor primario y el nivel preoperatorio de antígeno carcino-embrionario, se halló que aquellos pacientes que no recibieron HAC luego de la citorreducción tuvieron una probabilidad de muerte 3 veces mayor que los que recibieron HAC (RR 3.3, 95% CI 1.2 a 9.3). La sobrevida media estimada de los pacientes tratados con crioterapia sola fue de 245 días, en tanto que aquellos que recibieron HAC por tres meses y terapia de citorreducción fue de 570 días. Se recomienda que todos los pacientes que reciben crioterapia para metástasis hepáticas múltiples de carcinoma colo-rectal reciban luego quimioterapia por vía de la arteria hepática.

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Résumé Trente-huit patients ayant des métastases hépatiques multiples non reséquables d'origine colorectale ont été traités soit par chimiothérapie par voie artérielle (CVA) associée à la cryothérapie (n=27) soit par cryothérapie seule (n=11). Les survies ont été analysées selon la méthode d'analyse du Modèle de Cox. En tenant compte de l'effet de la pathologie de la tumeur primitive et du niveau préopératoire de l'ACE, les patients n'ayant pas eu de de décéder que ceux qui en ont eu (RR 3.3, 95% IC 12 à 9.3). L'estimation de la survie médiane des patients traités par la cytoréduction seule a été de 245 jours, alors que celle des patients traités par les deux avec une CVA d'au moins trois mois, a été de 570 jours. On recommande que tous les patients ayant des métastases multiples du foie à partir des cancers colorectaux aient une CVA par la suite.

     

Mortality among female registered nurses and school teachers in British Columbia

The mortality profile of female nurses and teachers in British Columbia (BC) was examined using age-standardized proportional mortality ratios (PMRs) calculated for the period 1950–1984. Lowered overall mortality among nurses was seen for degenerative heart disease and for cerebrovascular accidents. Significantly elevated PMR values were observed for cancer of the breast and ovary in nurses of age 20–65 years. PMRs were significantly elevated for cancer of the pancreas and leukemia among those age 20 years and older. Elevated values were also observed for motor vehicle accidents and suicide among nurses in both age groups. Lower than expected mortality from degenerative heart disease and cerebrovascular accidents was seen in working age teachers (age 20–65 years). However, elevated PMRs were detected for carcinoma of the colon, breast, endometrium, brain, and melanoma. Among those 20 years and over, significantly elevated PMRs were also observed for cancers of the ovary and other digestive organs. Elevated PMRs were found for motor vehicle and aircraft accidents. Mortality from cirrhosis of the liver was lower than anticipated in both teachers and nurses. A number of significant PMRs declined when deaths of “homemakers” were withdrawn from the comparison group used to generate PMR values, suggesting that risk of death from various causes among women working outside the home differ from those seen in women who are predominantly in the home.     

Early treatment of Class II, division 1 malocclusion--comparison of alternative treatment modalities.

The purpose of this paper was to compare the findings from three randomized clinical trials that investigated alternative treatments of Class II, division 1 malocclusion in young children. The trials were conducted at the University of North Carolina, the University of Florida, and the University of Pennsylvania. The appliances investigated in each center were a functional appliance versus a headgear. Variations in the specific aims and the working hypotheses were noted. The types of appliances, length of treatment, and methods of evaluation were also different. A general comparison of selected clinically relevant findings reveals similarities and differences in conclusions, but underlines the importance of assessing each study on the basis of its original hypothesis. The separate and combined contribution of these studies to the state of knowledge and research is discussed.     

A MODEL OF NURSE-MIDWIFE AND FAMILY PHYSICIAN COLLABORATIVE CARE IN A COMBINED ACADEMIC AND COMMUNITY SETTING

Certified nurse-midwives and family physicians share a philosophy of family-centered maternity care. Collaboration between the two disciplines, however, has not been common. Collaboration can enhance the primary care and maternity care options available to clients of such collaborative practices. Advantages and barriers to collaboration for both types of practitioners, as well as suggestions for successful collaboration, are discussed.