An information-processing perspective on childhood anxiety

In the past decade, cognitive theories of adult anxiety disorders have become increasingly complex, reflecting enhanced understanding of anxiety-related information-processing. This growth has fostered the development and enhancement of numerous assessment and treatment methods. Unfortunately, similar growth has been slower to occur in theories of childhood anxiety. This paper attempts to foster such growth by adopting an information-processing perspective. Doing so expands the extant cognitive perspective on childhood anxiety in four major ways. First, the division of cognitive processing into a sequence of steps provides a framework for organizing predictions regarding cognitive factors in childhood anxiety. Second, consideration of the cognitive operations active during each stage in the sequence facilitates elaboration of the types of cognitive deficits and distortions characteristic of anxious children. Third, it promotes development and application of performance-based assessment methodologies. Finally, an information-processing perspective highlights several targets for clinical intervention that may promote widespread change in an anxiety-supporting cognitive system.     

Polyvinylidene fluoride monofilament sutures: can they be used safely for long-term anastomoses in the thoracic aorta?

Polyvinylidene fluoride (PVDF) represents an attractive alternative to polypropylene as a monofilament vascular suture because of its satisfactory physicochemical properties, it ease of handling, and its good biocompatibility. However, the polymer's ability to remain mechanically and chemically stable when exposed to a mild hydrolytic environment over the long term has yet to be demonstrated. One in vitro study involved the comparison of the long-term relative resistance of PVDF and polypropylene sutures to hydrolysis for a period of 9 years. The PVDF suture showed major molecular rearrangements from the original ratio of three crystalline structures to the single beta crystalline phase. The observation of some surface oxidation and water inhibition did not significantly modify the tensile strength of the PVDF suture, which retained 92.5% of its original value. In contrast, the polypropylene sample did not undergo any recrystallization but was associated with more oxidation byproducts and more water molecules near the surface, which contributed to a 46.6% loss in initial tensile strength. An in vivo study confirmed that PVDF sutures are biocompatible and are able to maintain satisfactory biostability when used to anastomose thoracic aortic allografts for a period of 6 months in the dog. The cellular reaction of fresh allografts as well as the control autografts to PVDF sutures was minimal. In other allografts that had been preserved in a supplemented medium for 1 week prior to implantation, the PVDF sutures healed satisfactorily with the formation of neocollagen and few macrophages surrounding the monofilament. No evidence of instability at the allograft-host artery junction was observed, confirming that the PVDF sutures were able to ensure a secure anastomosis in the thoracic aorta. PVDF sutures have demonstrated superior long-term biostability in vitro and minimal tissue response in vivo. These are two essential requirements when evaluating the use of a suture for vascular surgery in general and thoracic aortic surgery in particular.     

Abnormal hepatic mitochondrial respiration and cytochrome C oxidase activity in rats with long-term copper overload

BACKGROUND: Dietary copper overload in the rat is associated with morphological abnormalities and lipid peroxidation of hepatic mitochondria. This study was designed to determine if copper hepatotoxicity was associated with functional alterations in mitochondrial respiration in conjunction with lipid peroxidation. METHODS: Weanling male rats were pair-fed for 8 weeks on diets containing normal or high levels of copper in combination with sufficient vitamin E. Serum and liver samples were obtained, and hepatic mitochondria were isolated by differential centrifugation. RESULTS: Oxidant injury (decreased levels of hepatic glutathione and alpha tocopherol and increased levels of mitochondrial thiobarbituric acid-reacting substances) was present in the copper-overloaded rats. Serum aminotransferase levels correlated with concentrations of mitochondrial copper and thiobarbituric acid-reacting substances. Copper overload caused a decrease in state 3 respiration and the respiratory control ratio in hepatic mitochondria when several electron donors were used. Analysis of the oxidoreductase activities of the four mitochondrial electron transport protein complexes showed that complex IV (cytochrome C oxidase) activity was reduced by 60% in copper overload. CONCLUSIONS: Functional abnormalities of mitochondria accompany lipid peroxidation and the morphological alterations caused by copper overload, supporting the hypothesis that the mitochondrion is one of the major intracellular targets in copper hepatotoxicity.     

The effects of guided tissue regeneration and fixation technique on osseous wound healing in rabbit zygomatic arch osteotomies

So called lethal midline granuloma is of great clinical and theoretical interest. Recent evidence has shown that most lethal midline granulomas are associated with a T-cell phenotype and they are therefore referred to as nasal T-cell lymphomas (NTCL). Immunohistochemical studies, however, have shown peculiar phenotypic features such as expression of natural killer (NK)-cell-related markers and extensive T-cell antigen loss including absence of expression of alpha beta T-cell receptor (TCR). In this study, we reported genotypic and immunohistochemical features in two cases of lethal midline granuloma. The histopathological diagnosis of the biopsy specimens was polymorphic reticulosis/midline malignant reticulosis. Both cases displayed a CD2+, CD3-, CD3 epsilon+, CD4-, CD8-, CD16-, CD56+ phenotype, suggesting that these tumors may be peripheral T-cell lymphomas with extensive loss of T-cell antigens and expression of NK cell antigen (CD56), or, alternatively, NK cell neoplasias. No TCR beta gene rearrangement was detected in these cases. Monoclonal Epstein-Barr virus (EBV) genome was detected in each specimen by Southern blot hybridization. The tumor cells in one of the two cases expressed latent membrane protein (LMP). These findings support the concept that lethal midline granuloma constitutes a distinct group of lymphomas that, in addition to their peculiar clinical features, exhibits the phenotype of extensive loss of T-cell antigens and expression of the NK cell antigen, as well as harbors the EBV. In view of the LMP-transforming potential, these data suggest that EBV may play a role in the pathogenesis of lethal midline granuloma.     

Sporadic visceral myopathy with inclusion bodies. A light-microscopic and ultrastructural study

We report the clinical and pathologic findings of two patients with sporadic visceral myopathy. Both presented with chronic intestinal pseudo-obstruction that necessitated colectomy. Microscopically, typical changes of primary visceral myopathy were present, including variable fibrous replacement of the muscularis externa and vacuolar degeneration of myocytes. In addition, the muscle cells contained cytoplasmic inclusions that have only been recently reported in visceral myopathy. These inclusions were numerous and easily visible in routine hematoxylin-eosin-stained sections but greatly enhanced by periodic acid-Schiff staining. They were reactive immunohistochemically at their periphery and were seen to be myofibrils at various stages of degeneration on electron microscopy. Inclusions were present in both muscularis externae and muscularis mucosae and were identified in mucosal biopsy specimens, providing a means of diagnosing this type of myopathic change on endoscopic biopsies.     

Clonidine therapy for comorbid attention deficit hyperactivity disorder and conduct disorder: preliminary findings in a children's inpatient unit

This retrospective study examined the clinical course of 18 prepubertal boys (aged 6 to 12) who had dual diagnoses of attention deficit hyperactivity disorder and conduct disorder and who received clonidine on an inpatient basis after failed trials of conventional drug therapy, consisting predominantly of psychostimulants. The effects of clonidine were assessed during inpatient treatment and after discharge at intervals of 1 to 2 months. Eleven (61%) of the children had marked improvement as measured by clinical impression. Transient sedation lasting 2 to 3 days occurred after initial administration or dosage increase; otherwise, clonidine was well tolerated. Our findings suggest that clonidine may prove to be an alternative treatment of comorbid attention deficit hyperactivity disorder and conduct disorder.     

Physiological regulation of early and late stages of megakaryocytopoiesis by thrombopoietin

Thrombopoietin (TPO) has recently been cloned and shown to regulate megakaryocyte and platelet production by activating the cytokine receptor c-mpl. To determine whether TPO is the only ligand for c-mpl and the major regulator of megakaryocytopoiesis, TPO deficient mice were generated by gene targeting. TPO-/- mice have a >80% decrease in their platelets and megakaryocytes but have normal levels of all the other hematopoietic cell types. A gene dosage effect observed in heterozygous mice suggests that the TPO gene is constitutively expressed and that the circulating TPO level is directly regulated by the platelet mass. Bone marrow from TPO-/- mice have decreased numbers of megakaryocyte-committed progenitors as well as lower ploidy in the megakaryocytes that are present. These results demonstrate that TPO alone is the major physiological regulator of both proliferation and differentiation of hematopoietic progenitor cells into mature megakaryocytes but that TPO is not critical to the final step of platelet production.