Premature failure of small-sized Shelhigh No-React porcine pulmonic valve conduit model NR-4000.

OBJECTIVE: Given the limited availability of small-sized cryopreserved pulmonary homografts, we implanted a series of Shelhigh No-React porcine pulmonic valve conduits (SPVC). The aim of this study was to evaluate the short-term performance following implantation. METHODS: From February 2000 to September 2000, the SPVC was implanted 25 times in 24 patients in the right ventricular outflow tract (RVOT) to correct congenital anomalies. The anatomical malformations were TOF/PA in eight patients, TGA/VSD/PS in four, truncus arteriosus in four, IAA/VSD/AS or AA in four, l-TGA/VSD in two and other in two. Age at operation was 2.8+/-3.9 years (mean+/-SD), including 12 patients under 1 year. The median conduit size was 14mm (range, 10-18). RESULTS: At a mean follow-up of 23+/-5 months, two late deaths (8%) have occurred. Although they were not primarily conduit related, both showed severe conduit stenosis. Twenty-one conduits (84%) showed mild to severe conduit stenosis, regurgitation or both. Two patients underwent balloon dilatation for distal conduit stenosis. Twelve conduits (48%) in 11 patients were removed at a median of 12 months (range, 2-18 months) due to RVOT obstruction in 11 and free conduit insufficiency with pseudoaneurysm in one. The typical findings of the explanted conduits were prominent intimal peel formation at the distal anastomosis without calcification. The actuarial freedom from reintervention at 18 months was 48+/-10%. CONCLUSIONS: Our experience of the SPVC with the diameter of 14mm or less has revealed a high incidence of distal conduit stenosis due to intimal peel formation resulting in early conduit failure. These findings have led us to abandon its use when other options are available.     

Vestibular-nerve inputs to the vestibulo-ocular reflex: a functional-ablation study in the squirrel monkey

Advantage was taken of differences in the electrical excitability of vestibular-nerve fibers to characterize the afferent input to the canal-related vestibulo-ocular reflex. Large anodal (inhibitory) currents, when delivered to both ears, result in a selective, reversible ablation of irregular afferents. Their background discharge and responses to head rotations are temporarily abolished. The same currents have less effect on the background discharge and no effect on the rotational sensitivity of regular afferents. Eye movements were evoked by head rotations in alert monkeys. The ablating currents did not alter the ocular responses to sinusoidal head rotations in yaw or pitch planes. Responses to rapid changes in head velocity were similarly unaffected. It is concluded that irregular afferents do not make a net contribution to the reflex. Slow-phase eye movements evoked by unilateral galvanic currents are consistent with this conclusion. The results are incorporated into a systems model of the reflex. There are three conclusions from the model: (1) the signal to motoneurons consists of the sum of three components related, respectively, to head velocity, eye position, and filtered eye velocity; (2) regular afferents provide the best match to the dynamic requirements of the reflex; and (3) the central pathways responsible for all three signal components receive regular inputs.     

Further morphological and biochemical observations on early low dose streptozocin diabetes in mice.

Conflicting published data regarding the role of macrophages and other cell types during the early stages of diabetes mellitus led us to further study this problem. To this end we diabetized mice, using low doses of streptozocin (STZ), 40 mg/kg body wt/day/5 days, and processed their pancreatic tissue for immunocytochemistry and ultrastructural observations; immunohistochemistry was performed on days 5 and 18 after the first STZ injection, and islets were observed ultrastructurally on days 5, 9, 10, and 18. Animals were tested for fasting serum glucose, and isolated islets were assayed for insulin secretion capacity. Immunohistology demonstrated that expression of major histocompatability complex class 2 antigens is strongly induced by multiple, low dose STZ treatments prior to impaired insulin release, and that different types of cells within the islet are capable of expressing Ia molecules. Ultrastructurally we found (a) a small number of macrophages (most probably resident monocytes/macrophages) containing B-cell debris, that were located close to either damaged or intact B cells; (b) a large number of recruited macrophages in a vascular or perivascular position; and (c) macrophages recognizable in the exocrine portion, close to the islets, occasionally containing exocrine cell debris. This led us to believe that recruited macrophages play an important role in the early islet-infiltrating stage.     

Link between the ability to detect and manage emotional disorders: a study of general practitioner trainees.

Independent ratings were made of videotaped consultations involving six general practice vocational trainees, of whom three were poor identifiers and three were able identifiers of emotional illness. Taped consultations were selected so that each trainee was rated interviewing five patients with low general health questionnaire scores, and five patients with high scores. It was found that able identifiers of emotional illness were more likely than poor identifiers to offer patients information, advice and treatment relevant to their illness, and that they did so in a manner likely to maximize patient satisfaction and cooperation. This was true for both distressed and non-distressed patients. It is argued that both the ability to identify emotional disturbances and the ability to manage emotional illness are characteristics of a generally superior interview style. This may reflect a common variable: the possession of good communication skills.     

Preliminary analysis of a randomized comparison of 5-fluorouracil versus 5-fluorouracil and high-dose continuous-infusion folinic acid in disseminated colorectal cancer

In this study, 50 patients were randomly assigned to treatment with 5-fluorouracil (FUra) or FUra plus high-dose continuous-infusion folinic acid. Five of 27 evaluable patients in the FUra group versus 10 of 21 patients in the FUra plus folinic acid arm of the study had objective partial remissions, P = 0.02. Time to progression was 3.9 months for FUra and 8.0 months for FUra and folinic acid, P = 0.006; however, median survivals (11.9 versus 14.5 months) were not different in this crossover study. Toxicity in both treatment arms was mild, although patients receiving FUra plus folinic acid experienced significantly more stomatitis than patients treated with FUra alone. This study suggests that high-dose, continuous-infusion folinic acid, which produces a steady-state level of biologically active folates of 10 microM, significantly increases the therapeutic activity of FUra.     

Longitudinal predictors of continued tobacco use among patients diagnosed with cancer

Even though continued smoking by cancer patients adversely affects survival and quality of life, about one third of patients who smoked prior to their diagnosis continue to smoke after their diagnosis. The implementation of smoking cessation treatments for cancer patients has been slowed by the lack of data on correlates of tobacco use in this population. Thus, this longitudinal study assessed demographic, medical, addiction, and psychological predictors of tobacco use among 74 head, neck, and lung cancer patients. Multivariable binary logistic regression analyses, with outcome categorized as smoker or nonsmoker, indicated that the likelihoodthat patients would be a smoker was associated with lower levels of perceived risk and a higher level of quitting cons. Multivariable nominal logistic regression, with outcome classified as continuous smoker, continuous quitter, relapser, or follow-up quitter, indicated that: (a) patients categorized as continuous smokers reported significantly lower quitting self-efficacy than follow-up quitters and continuous quitters, (b) relapsers reported a significantly lower level of quitting self-efficacy than either follow-up quitters or continuous quitters, and (c) continuous smokers exhibited a significantly lower level of risk perceptions than continuous abstainers. These findings can be useful for the development and evaluation of treatments to promote smoking cessation among cancer patients. Support for this study was provided by National Institutes of Health Grants CA57708, CA06927, CA88610, CA95678, and CA76644.