Quantitative relationship between global left ventricular thallium uptake and blood flow: effects of propranolol, ouabain, dipyridamole, and coronary artery occlusion

The quantitative relationship between fractional myocardial thallium uptake and radioactive microsphere-determined flow was studied in 33 open chest dogs under baseline conditions during increased coronary flow (dipyridamole), decreased coronary flow (propranolol and coronary artery stenosis), inhibition of Na-K ATPase (ouabain), and regional infarction. Myocardial contents of thallium and microspheres were compared in left ventricular (LV) biopsies taken 5, 10, 15, 30, and 60 min after thallium injection, expressed as fractions of injected dose. Maximal LV thallium uptake occurred 10 min after injection and the 10-min values were therefore used for subsequent comparisons. Combining all dogs, fractional LV thallium content (% injected dose) correlated well with fractional LV blood flow (% cardiac output) (r = 0.95). However, for fractional LV flows in the low, normal, or moderately elevated range (LV flow/cardiac output less than 9%), thallium content consistently exceeded flow by about 15%. This relationship was not altered by ouabain or regional ischemia or infarction. For greatly elevated fractional LV flows (greater than 9%), thallium content was not significantly different from flow. To explain these differences, myocardial and systemic extraction fractions for thallium were determined in eight dogs with a dual tracer method. At baseline, myocardial extraction fraction was significantly greater than systemic (88 +/- 0.4% compared with 75 +/- 1%, p less than 0.001). During dipyridamole, myocardial extraction fraction decreased and myocardial and systemic values were no longer significantly different (82 +/- 1% compared with 79 +/- 1%). These results show that the fraction of injected thallium dose taken up by the LV myocardium exceeds the delivered fraction of cardiac output over a wide range of LV flows, and is not altered by ouabain-induced inhibition of sodium-potassium ATPase or regional myocardial infarction. This difference is explained by a greater myocardial than systemic extraction fraction for thallium. During high LV flows produced by dipyridamole, fractional LV thallium uptake and flow become similar as myocardial and systemic extraction fractions equalize.     

A case of multiple primary tumors of the anterior skull base.

We report a case of synchronous olfactory bulb meningioma and undifferentiated carcinoma of the nose and paranasal sinuses that involved and destroyed the anterior skull base and mimicked intracranial invasion by a carcinoma. The heterogeneity of tissue types in the skull base gives rise to a diverse variety of benign and malignant neoplasms which have totally different prognoses. Synchronous development of benign and malignant primary tumors both originating from and involving the skull base at the same location is very rare and may cause confusion for both the skull base surgeon and neuroradiologist.     

Emergency orthodontic treatment after the traumatic intrusive luxation of maxillary incisors.

Treatment of traumatically intruded teeth is based largely on empirical clinical experience rather than on scientific data. The aim of this qualitative meta-analysis was to provide an evidence base to evaluate the orthodontic repositioning approach. In a MEDLINE search of the literature in English, 14 reported patients involving 22 teeth were found to have been treated by this modality. Additionally, 3 new patients, involving 9 intruded teeth and presented herein, were combined to form a total study sample of 17 subjects (7 girls, 10 boys, aged 8.9 +/- 1.2 years). Orthodontic extrusive forces were applied in the immediate posttrauma period (up to 3 months), with a variety of orthodontic appliances. Repositioning was achieved for 90.3% of the affected teeth but failed in 9.7% because of inflammatory resorption (2 teeth) or a misdiagnosis of root fracture (1 tooth). Early complications included loss of pulp vitality and external root resorption. All intruded teeth with closed root apices lost their vitality regardless of the degree of intrusion, whereas among those with incomplete apices, 45.5% that had been moderately intruded remained vital. External resorption was encountered in 54.8% of the teeth. Loss of marginal bone support was rarely encountered. Late complications included inflammatory root resorption in teeth with closed apices, in which endodontic treatment was not initially performed, and obliteration of the pulp tissue in teeth that remained vital. The results show that this method is superior to other treatment alternatives.     

Relaxin down-regulates renal fibroblast function and promotes matrix remodelling in vitro.

BACKGROUND: Renal fibroblasts are important effector cells in tubulointerstitial fibrosis, with experimental antifibrotic strategies focusing on the functional down-regulation of these cells. Several experimental models of fibrosis have provided evidence for the effectiveness of the polypeptide hormone relaxin as a potential antifibrotic agent. This study was conducted to further elucidate the antifibrotic mechanisms of relaxin on renal fibroblasts in vitro. METHODS: Rat cortical fibroblasts were obtained from outgrowth culture of renal tissue isolated from kidneys 3 days post-unilateral ureteric obstruction and constituted 100% of cells studied. A relaxin radio-receptor assay was used to establish binding of relaxin to renal fibroblasts in vitro. Functional studies then examined the effects of H2 relaxin (0, 1, 10 and 100 ng/ml) on fibroblast kinetics, expression of alpha-smooth muscle actin (alpha-SMA), total collagen synthesis, collagenase production and collagen-I lattice contraction. CTGF mRNA expression was also measured by northern analysis. RESULTS: H2 relaxin bound with high affinity to rat renal fibroblasts, but receptor numbers were low. Consistent with its previously reported bimodal effect, transforming growth factor (TGF-beta 1) reduced fibroblast proliferation, an effect abrogated by H2 relaxin. Fibroblasts exposed to H2 relaxin (100 ng/ml) for 24 h demonstrated decreased immunostaining for alpha-SMA and reduced alpha-SMA protein expression compared with controls. There was a trend for a relaxin-mediated reduction in total collagen synthesis and alpha 1(I) mRNA expression with large dose-related increases in collagenase protein expression being observed. TGF-beta 1-stimulated collagen-I lattice contraction was significantly inhibited following co-incubation with 100 ng/ml relaxin. Incremental doses of H2 relaxin had no significant effect on CTGF mRNA expression. CONCLUSIONS: The findings of this study suggest that the antifibrotic effects of relaxin involve down-regulation of fibroblast activity, increase in collagenase synthesis and restructuring of collagen-I lattices, which are consistent with its known physiological role of matrix remodelling. Although there appears to be an interaction between TGF-beta 1 and H2 relaxin, this does not appear to involve a reduction in CTGF mRNA expression.     

Cytofluorometric analysis of thymic interdigitating cells from C57BL/6 mice prior and after leukemogenic X-irradiation

The thymus is populated by various Ia+ cell populations, including epithelial cells, macrophages and dendritic cells. Thymic cell suspensions were stained with an anti-Ia antibody and shown by cytofluorometry to contain a small number of strongly Ia+ cells characterized by a large diameter. The cell population was separated with the aid of the fluorescence-activated cell sorter (FACS) and characterized. They were shown to express high levels of membranal Ia antigens; they demonstrated ATPase activity and displayed the ultrastructural features characteristic of the previously described thymic interdigitating cells. C57BL/6 mice were submitted to various regimens of X-irradiation. Whereas exposure to a single dose of X-irradiation was followed by an increase in the percentage of strongly Ia+ cells, exposure to a leukemogenic regimen of fractionated X-irradiation led to a decrease in the percentage and absolute numbers of these cells in the thymus. Of the C57BL/6 mice that were irradiated with fractionated X-irradiation, 77% developed leukemia. Intravenous injection of syngeneic bone marrow one day following the last irradiation or protection of the femur during irradiation prevented both the appearance of leukemia and the disappearance of interdigitating cells. Therefore an inverse correlation between the presence of thymic dendritic cells and the incidence of leukemia in C57BL/6 mice could be demonstrated. These findings are discussed in relation to the putative role of dendritic cells in the thymus.     

C2H2-171 : A novel human cDNA representing a developmentally regulated poz domain/zinc finger protein preferentially expressed in brain

We describe a novel human zinc finger cNDA, C2H2-171. This cDNA represents an mRNA which encodes a protein of 484 amino acids and a calculated molecular weight of 54 kD. Four zinc finger-like domains are found in the C-terminal end of the protein. At the N-terminus, C2H2-171 contains a POZ/tramtrack-like domain similar to that found in the tumor associated zinc finger proteins LAZ-3/BCL-6 and PLZ-F, as well as in non-zinc finger proteins. C2H2-171 RNA is preferentially expressed in the brain, and increases during the course of murine development, with maximal expression in the adult. C2H2-171 RNA is differentially expressed in brain regions, with the highest level of expression in the cerebellum. C2H2-171 RNA was expressed at high levels in primary cerebellar granule cell neurons compared to astrocytes. The gene encoding C2H2-171 is highly conserved in vertebrates, and maps to the terminus of human chromosome 1 (1q44-ter). This chromosomal location is associated with a number of cytogenetic aberrations including those involving brain developmental anomalies and tumorigenesis. These data suggest that C2H2-171 may play an important role in vertebrate brain development and function.     

Reduced virulence of Candida albicans mutants affected in multidrug resistance.

Disruption of a multidrug resistance gene (CaMDR1) in Candida albicans resulted in mutant strains that colonized mouse kidneys to very high levels but were markedly reduced in their virulence. No obvious differences in several properties related to colonization and dissemination were noted among MDR+ or mdr- strains. These results suggest that specific fungal efflux pumps play a role in fungal pathogenicity.