Ultrasonography of the urinary bladder

Summary Ultrasonography of the urinary bladder has evolved with improvements in ultrasound instrumentation. The bladder may be visualized transabdominally, transurethrally, and transrectally. Bladder tumors may be accurately staged. Postvoiding residual urine may be measured accurately and noninvasively. As newer indications are evaluated, including ultrasound imaging of the bladder during urodynamic studies, ultrasound of the bladder will be performed more readily by urologists.     

Flexible Sigmoidoscopy Screening in an Industrial Setting

Little is known about the yield of colorectal cancer screening programs in an industrial setting. We therefore established a flexible sigmoidoscopy screening program at a chemical manufacturing plant and offered testing to all employees over the age of 40. After a Fleet enema preparation had been administered, a digital rectal examination and sigmoidoscopy were performed on each volunteer worker in the medical office of the plant. The plant had an average census of about 650 workers; 202 were screened during a 2-yr period. The mean (+/- SEM) age of participants was 52 +/- 0.4. Sixty-four employees had polyps (31.7%); data on follow-up colonoscopy were available in 69%. Colonoscopy revealed adenomatous polyps in 23 workers (53.5%), hyperplastic polyps in 10 (23%), and no evidence of neoplasia in 10 (23%). Seven workers did not arrange for follow-up colonoscopy and 12 individuals could not be contacted. No cancers were detected. In the 40- to 50-yr age group, polyps were detected in 19.5% of employees (25% adenomatous). Incidental findings were common, and included prostatic nodules, hemorrhoids, diverticulosis, and proctitis, among others. We conclude that screening sigmoidoscopy can be conveniently and economically performed at the workplace, with a high yield and good worker acceptance. The high yield suggests a possible association between polyp formation and work in a chemical plant. The finding of adenomatous polyps in the younger patients suggests that the threshold for flexible sigmoidoscopy at age 50 needs to be reassessed.     

Metabolic expression of intrinsic developmental programs for dentine and enamel biomineralization in serumless,chemically-defined,organotypic culture

Summary Biomineralization was investigated using embryonic mouse mandibular first molars (M₁) cultured in the presence or absence of fetal calf serum. Metabolic features including cell division and Ca²⁺ and phosphate incorporation into dentine and enamel extracellular matrices were analyzed. The relative timing and magnitude of DNA synthesis for serumless cultures was comparable toin vivo controls. Isotopic calcium and phosphate incorporation into the mineral phase of dentine and enamel matrices, in the absence of serum, fluctuated during development. Molar tooth morphogenesis, cytodifferentiation, and extracellular matrix formation approximated late crown-stage development in serumless cultures. Von Kossa histochemical staining indicated calcium phosphate salt formation in serumless cultures. Analysis of anhydrous fixation-prepared enamel and dentine representing serumless cultured explants indicated that crystal size and orientation were comparable toin vivo enamel and dentine. In contrast, serum-supplemented cultures showed atypical crystal size and orientation. Calcium/phosphorous (Ca/P) ratio values for serumless cultures after 21 days showed Ca/P enamel values of 2.03 (SD±0.04, p<0.025) and dentine values of 1.89 (SD±0.01, p<0.025). Electron diffraction patterns of enamel and dentine formed in serumless cultures were principally those of highly-ordered crystalline hydroxyapatite. Our results suggest that tissue-specific dentine and enamel biomineralization is regulated by endogenous factors intrinsic to the developmental program of embryonic tooth organs during serumless culture.     

De-regulation of endogenous retrotransposons in mouse mammary carcinomas of diverse etiologies

Of the several families of endogenous retrovirus-like elements present in the mouse genome, only mouse mammary tumor virus has been analyzed for its role in mammary carcino-genesis. Very little is known about the expression and activities of other retro-elements in normal and malignant mammary epithelium. We have begun investigating the possible involvement of the 3 retrotransposons, intracisternal A particles (IAPs), murine-leukemia-virus-related (MuLVr) elements, and VL30 sequences, in neoplastic progression of the mammary gland in BALB/c mice. The purpose of the present study was to determine which of these elements was active in primary mammary carcinomas induced by chemical, hormonal and viral agents. Each of these cancers had aberrant expression of at least one of the latter retrovirus-like components. IAP and/or MuLVr sequences were over-expressed 3 to 100-fold in most of the tumors as compared with normal mammary tissue, whereas VL30 expression was markedly decreased by 5- to 35-fold in almost all of the neoplasms. Our results thus demonstrate that substantial changes in the expression of one or more of these 3 families of endogenous retrotransposons are triggered during mouse mammary tumorigenesis, regardless of etiology. Direct involvement of lAPs and MuLVr elements in neoplastic progression by transposition and insertional mutagenesis in the genome of several hematopoietic cell types has already been demonstrated. Their elevated expression in many mammary carcinomas suggests that these retrotransposons may also be potential participants in some pathways of mouse mammary carcinogenesis.     

Use of epr oximetry with india ink to measure the po2 in the liver in vivo in mice

The partial pressure of oxygen (pO₂) of the liver in vivo in unanesthetized mice was determined using electron paramagnetic resonance (EPR) oximetry with India ink. The EPR spectra were obtained using a low-frequency (1.2 GHz) EPR spectrometer with a loop gap cavity resonator. The line width of the India ink used in this experiment was reversibly broadened by oxygen and was particularly sensitive to pO₂ below 30 torr. After the administration of India ink into the tail vein, the India ink particles were taken up mainly by Kupffer cells in the liver and in part by phagocytes in the spleen. The pO₂ measured in the normal liver was about 14 torr and was constant for the 2-week experimental period. The pO₂ decreased when measured at 1, 2, and 6 days after treatment with a hepatotoxin (carbon tetrachloride (CCI₄)); within 2 weeks, it returned almost to the initial level. Measurements by EPR at sacrifice of controls and CCI₄-treated mice indicated that more than 90% of the India ink went to the liver; the spleen contained 4.7% of total amount in control mice and 8.8% in CCI₄-treated mice when measured 2 weeks after the treatment. These data indicate the usefulness of India ink for measuring the pO₂ of the liver in vivo and that the pO₂ in the Kupffer cells is decreased when the liver is damaged by CCI₄.     

Glutathione effects on vitamin D metabolism in control and streptozotocin diabetic rat

The circulating concentration of 1,25-dihydroxycholecalciferol [1,25-(OH)₂D₃] is a physiologic index of enzymatic activity of the renal 1-hydroxylase of 25-hydroxychole-calciferol (25-OH-D₃). Hydroxylation of 25-OH-D₃ and circulating 1,25-(OH)₂D₃ are decreased in the streptozotocin diabetic rat. We previously found that activity of another redox enzyme system, cytosolic superoxide dismutase, also decreased in streptozotocin diabetes, can be restored by treatment with glutathione. In the present experiment we tested the effect of glutathione treatment on vitamin D metabolism in control and diabetic rats. Enteral glutathione increased circulating 1,25-(OH)₂D₃ and decreased 25-OH-D₃ in both control and diabetic animals. These results suggest that exogenous glutathione increases 25-OH-D₃ 1-hydroxylation both under basal conditions in the normal animal and in diabetes-induced depression.