Hepatic processing of transforming growth factor beta in the rat. Uptake, metabolism, and biliary excretion.

Transforming growth factor beta (TGF beta), a recently discovered polypeptide, modulates growth of normal and neoplastic cells. Since little is known concerning in vivo disposition of TGF beta, we performed studies to examine the hepatic processing of biologically active 125I-TGF beta in the rat. After intravenous injection, 125I-TGF beta disappeared from the plasma with an initial t1/2 of 2.2 min; partial hepatectomy delayed the plasma disappearance of 125I-TGF beta by 80%. 60 min after intrafemoral injection, 63% of the recovered label was present in liver and/or bile; by 90 min, most of the label removed by the liver (83%) had been slowly excreted into bile. Nearly all the label in bile (96%) was soluble in trichloracetic acid and not immunoprecipitable by specific antiserum. Colchicine and vinblastine inhibited cumulative biliary excretion of label by 28 and 37%, respectively; chloroquine and leupeptin each increased the amount of label in bile that was precipitable by trichloracetic acid and that coeluted with authentic 125I-TGF beta on molecular sieve chromatography. There was efficient first-pass hepatic extraction of 125I-TGF beta (36%) in the isolated perfused rat liver, which was inhibited by unlabeled TGF beta (but not by epidermal growth factor, EGF) and by lectins in a dose-dependent manner; prolonged fasting also decreased clearance (26%). After fractionation of liver by differential or isopycnic centrifugation, radiolabel codistributed with marker enzymes for lysosomes. The results indicate rapid, extensive, inhibitable, and organ-selective extraction of TGF beta by the liver. After extraction, TGF beta undergoes efficient transhepatic transport, extensive intracellular metabolism, and slow but complete biliary excretion of its metabolites. Liver fractionation studies and pharmacologic manipulations suggest that these processes are associated with organelles that include microtubules and lysosomes. The data suggest that the liver is a major target tissue or site of metabolism for biologically active TGF beta.     

Amphiregulin messenger RNA is elevated in psoriatic epidermis and gastrointestinal carcinomas.

Amphiregulin (AR) is a heparin-regulated, epidermal growth factor-like growth factor capable of stimulating the proliferation of non-tumorigenic cells while inhibiting cell proliferation in some human tumor cell lines in vitro. In the present study, we have investigated AR mRNA expression in normal, hyperproliferative, and neoplastic human epithelium. Our results demonstrate that, compared with the adjacent uninvolved epithelium, AR mRNA expression is markedly elevated in epidermal biopsies derived from three human psoriatic lesions as well as in biopsies derived from five human colon carcinomas and three human stomach carcinomas. Moreover, analysis of a colon carcinoma by in situ hybridization revealed that AR mRNA is localized to the epithelium.     

Comparison of Snellen letter and Vistech grating charts as refraction targets

Snellen letter and Vistech sine wave grating charts were used as refraction targets to determine differences in times required to accomplish subjective refractions, endpoint refractive values, and subject preferences. Thirty hyperopes and 30 myopes, divided into three age groups, were selected as subjects. Two examiners tested each subject using each chart. Both timed their subjective refractions and recorded their findings. After all data were recorded, each subject completed a questionnaire to determine chart preference. There were no clinically significant mean differences between the charts in terms of endpoint refractive data, but, on average, the Snellen chart was faster to use. Chart rating depended on the subject's refractive status with more myopes preferring the Snellen chart and more hyperopes rating the grating chart higher.     

Transformation of the oomycete pathogen Phytophthora megasperma f. sp. glycinea occurs by DNA integration into single or multiple chromosomes

A procedure for stable transformation was developed for Phytophthora megasperma f. sp. glycinea, an oomycete pathogen of soybean. Transformants were obtained using a bacterial hygromycin resistance gene fused to a promoter and terminator from the ham34 gene of another oomycete, Bremia lactucae. Vector DNA, alone or complexed to cationic liposomes, was introduced into protoplasts using polyethylene glycol and CaCl₂. DNA and RNA hybridization, and phosphotransferase assays, confirmed the presence and expression of vector DNA in the transformants. Hybridization to electrophoretically separated chromosomes of P. m. glycinea showed that vector DNA had integrated into only one chromosome in four transformants, and into multiple chromosomes in one transformant.     

Long-term preservation of cortically dependent visual function in RCS rats by transplantation.

Cell transplantation is one way of limiting the progress of retinal degeneration in animal models of blinding diseases such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Here we transplanted a human retinal pigment epithelial (RPE) cell line into the subretinal space of one such model, the Royal College of Surgeons (RCS) rat, and showed, using head tracking to moving stripes and pattern discrimination in conjunction with single-unit cortical physiology, that cortically mediated vision can be preserved with this treatment.     

Prostate Stem Cell Compartments : Expression of the Cell Cycle Inhibitor p27Kip1 in Normal, Hyperplastic, and Neoplastic Cells

The stem cells of rapidly renewing tissues give rise to transiently proliferating cells, which in turn give rise to postmitotic terminally differentiated cells. Although the existence of a transiently proliferating compartment has been proposed for the prostate, little molecular anatomical evidence for its presence has been obtained to date. We used down-regulation of the cyclin-dependent kinase inhibitor p27^Kip1 to identify cells capable of entering the proliferative phase of the cell cycle and, therefore, competent to fulfill the role of the transiently proliferating compartment. We examined the expression of p27^Kip1 in relation to its role in the development of prostatic carcinoma. Formalin-fixed paraffin-embedded specimens from matched samples of normal-appearing prostate tissue, benign prostatic hyperplasia, high-grade prostatic intraepithelial neoplasia, primary adenocarcinomas, and pelvic lymph node metastases were evaluated by comparative immunohistochemistry against p27^Kip1. In normal-appearing prostate epithelium, moderate to strong nuclear staining of p27^Kip1 was present in greater than 85% of the terminally differentiated secretory cells. The normal basal cell compartment, believed to contain prostatic stem cells, showed distinctive p27^Kip1 expression; acini in epithelial benign prostatic hyperplasia tissue contained more p27^Kip1-negative basal cells than acini from non-benign prostatic hyperplasia tissue. A third layer of cells was identified that was sandwiched between the basal cells and the luminal cells, and this layer was consistently p27^Kip1 negative. This intermediate layer was accentuated in the periurethral region, as well as in prostate tissue that had been subjected to prior combined androgen blockade. We hypothesize that, on appropriate additional mitogenic stimulation, cells in this layer, and other p27^Kip1-negative basal cells, are competent for rapid entry into the cell cycle. Consistent with the fact that cancer cells are capable of cell division, all cases of high-grade prostatic intraepithelial neoplasia and invasive carcinoma also showed down-regulation of p27^Kip1 as compared with the surrounding normal-appearing secretory cells. In pelvic lymph node metastases, p27^Kip1 expression was also reduced. In summary, our results suggest that lack of nuclear p27^Kip1 protein may delineate a potential transiently proliferating subcompartment within the basal cell compartment of the human prostate. In addition, these studies support the hypothesis that reduced expression of p27^Kip1 removes a block to the cell cycle in human prostate epithelial cells and that dysregulation of p27^Kip1 protein levels may be a critical early event in the development of prostatic neoplasia.     

Life events and early onset depression: cause or consequence?

BACKGROUND: Adverse life events prior to episodes of depression are assumed to play a causal role. Earlier studies have, however, not adequately controlled for the potential confounding effects of previous depression. METHOD: A two-phase study was nested within a six-wave population based cohort study of 1947 adolescents. Interviews at two assessment phases with the CIS-R and CIDI were used to generate ICD-10 diagnoses of depressive disorder. Life events with longer-term contextual threat were reported for the 6 months before first diagnosis and categorized on the basis of participant appraisal as negative and neutral/positive in effects. Previous depressive and anxiety symptoms were measured 6 months earlier. RESULTS: Pre-existing depressive and anxiety symptoms predicted later events, increasing three-fold the risks for both neutral/positive and negative events in females and increased seven-fold the risk of negative events in males. Life events in turn predicted the onset of depressive disorder independently of previous symptoms. Single negative events held an over five-fold elevated risk and multiple events an almost eight-fold higher risk. Personal threat and loss were associated with disorder in females but not males. CONCLUSIONS: The findings are consistent with a causal role for life events in early episodes of depression. The association also reflects a reciprocal relationship in which earlier symptoms predict later events, perhaps as a result of an individual's attempts to change unfavourable social circumstances.     

Acute coronary syndromes

The first 150 words of the full text of this article appear below. Key points Coronary artery disease accounts for >30% ofdeaths in Western society. The diagnosis of myocardial infarctionshould be qualified by size, causation and time from occurrence. Mortalityis reduced by immediate or ‘primary’ percutaneouscoronary intervention or thrombolysis within the first 24 hof onset of ST-segment elevation myocardial infarction. Strategiesto reduce platelet activation (glycoprotein IIb/IIIa receptorantagonists, or clopidogrel) are now recommended in the treatmentof high-risk non-ST-segment myocardial infarction/unstable angina. Elevatedserum troponins may be the result of non-ischaemic myocardialdamage, especially in critical illness.