The agent of Human Granulocytic Ehrlichiosis resides in an endosomal compartment.

The composition of cytoplasmic vacuoles containing the agent of Human Granulocytic Ehrlichiosis (HGE) was studied to investigate how this pathogen exists within infected host cells. Electron microscopy demonstrated that the HGE organism resides in a membrane-bound compartment within HL-60 cells: early forms of the HGE agent have a round reticular appearance while later structures are small and dense. Vacuoles containing HGE bacteria incorporated endocytosed colloidal gold particles, suggesting that they are part of the endocytic pathway. Antibodies directed to the mannose-6-phosphate receptor labeled vacuole membranes. Antibodies to the transferrin receptor and to the lysosomal membrane glycoprotein LAMP 1 did not. Moreover, 3-(2,4-dinitroanilino)-3'-amino-N-methyldipropylamine, which normally accumulates in compartments with low pH, was not present inside these vacuoles. These results suggest that vacuoles containing the agent of HGE fail to mature into phagolysosomes. We conclude that the agent of HGE appears to enter and modify part of the endocytic pathway.     

Short-Ti inversion-recovery pulse sequence: analysis and initial experience in cancer imaging

Inversion recovery (IR), commonly considered a pulse sequence capable of producing T1-weighted images with excellent display of normal anatomy, is versatile: The null point and peak time provide a useful, succinct summary of the properties of IR and its capacity for producing both T1- and T2-weighted images. Shortening of the inversion time (TI) and creation of a short-TI inversion-recovery (STIR) pulse sequence increases sensitivity to malignancy and other abnormalities by making the effects of prolonged T1 and T2 on signal intensity additive and by nulling the signal from fat. The authors examined over 300 patients with various malignancies and compared STIR images with T1- and T2-weighted images obtained at 0.5 T. In 43 cases, signal-difference-to-noise ratios (SD/Ns) were calculated between tumor, fat, and muscle. In general, STIR images demonstrated tumor as a conspicuously high-intensity area in a background of muted, discernible anatomic detail. The good contrast achieved with STIR sequences between tumor and fat (SD/N = 18.1) and tumor and muscle (SD/N = 12.9) consolidated into a single image the information contained separately on T1- and T2-weighted images, which facilitates efficient detection and localization of malignancy.     

Solitary rectal ulcer syndrome: findings at barium enema study and defecography

Sixteen cases of histopathologically proved solitary rectal ulcer syndrome were encountered. Fifteen patients underwent barium enema study; in nine cases the findings--including rectal stricture, granularity of the mucosa, and thickened rectal folds-were nonspecific. In six cases the study was normal. All patients had a long history of defecation disorders, and defecography was performed in all. In seven cases, intussusception of the rectal wall was seen; in another case the intussusception was accompanied by a rectocele. One case showed rectal prolapse. In four cases, failed relaxation of the puborectalis occurred and prevented the passage of the bolus; in another case there was abnormal perineal descent. In two patients studies were normal. In patients with defecation disorders, the possibility of this syndrome should be considered. Defecography is the method of choice for establishing the diagnosis.