Collagen metabolism in mouse lung after X irradiation

Collagen and total protein synthesis rates have been determined in the lungs of CBA mice irradiated with single doses of X rays between 8 and 16 Gy. Mice were injected with [3H]proline accompanied by a large dose of unlabeled proline, and synthesis rates were measured at 2-month intervals from 8 to 31 weeks after irradiation. At 2 months after radiation treatment, collagen and total protein synthesis rates were significantly depressed but they had recovered by 4 months. By 6 months collagen synthesis rates had increased above control in a dose-dependent manner, so that in the 14-Gy dose group the fractional synthesis rate for collagen was 4.6 times higher than in control mice as measured by incorporation of [3H]proline. However, a significant net accumulation of collagen was seen only in the lungs of the highest dose group at 31 weeks, as indicated by total hydroxyproline measurements. There was a slight increase in the ratio of types I and III collagen. Late radiation damage in the CBA mouse lung is characterized by increased collagen metabolism, which may or may not lead to a net accumulation of collagen.     

Human papillomavirus type 16 DNA cooperates with activated ras in transforming primary cells.

The close association of human papillomavirus type 16 DNA with a majority of cervical carcinomas implies some role for the virus in this type of cancer. To define the transforming properties of HPV-16 DNA in vitro we have now performed transfection experiments on baby rat kidney cells using HPV-16 DNA in conjunction with an activated ras gene. We have demonstrated that a 6.6-kb DNA fragment, containing the early genes of HPV-16 under the control of Moloney murine leukaemia virus long terminal repeats (MoMuLV-LTRs), cooperates with EJ-ras in transforming these cells. Both DNAs are required and neither alone is effective. The cooperating activity appears to reside in a protein or proteins derived from the E6/E7 region of the HPV-16 genome.     

Identification of a novel adhesion molecule in human leukocytes by monoclonal antibody LB-2

Monoclonal antibody LB-2 to a surface antigen on human B cells, lymphoblast, monocytes and vascular endothelial cells largely inhibited adhesion among Epstein Barr virus-immortalized normal B cells (EBV-B) and concanavalin A-stimulated blood mononuclear cells (Con A-BMC) before and after phorbol ester treatment. The antibody inhibited to a lesser extent phorbol ester-induced aggregation of monocytes, U937 cells and fresh BMC and had virtually no inhibitory effect on the adhesion among enriched T cells and granulocytes. A surface glycoprotein band of 84 kDa was obtained from EBV-B cells by immunoprecipitation and gel electrophoresis. Immunological and biochemical studies clearly distinguished this molecule from gp90 and associated glycoproteins which also mediate leukocyte adhesion.     

Regulation of inositol phospholipid and inositol phosphate metabolism in chemoattractant-activated human polymorphonuclear leukocytes

Binding of chemoattractants to specific cell surface receptors on polymorphonuclear leukocytes (PMNs) initiates a series of biochemical responses leading to cellular activation. A critical early biochemical event in chemoattractant (CTX) receptor-mediated signal transduction is the phosphodiesteric cleavage of plasma membrane phosphatidylinositol 4,5-bisphosphate (PIP2), with concomitant production of the calcium mobilizing inositol-1,4,5-trisphosphate (IP3) isomer, and the protein kinase C activator, 1,2-diacylglycerol (DAG). The following lines of experimental evidence collectively suggest that CTX receptors are coupled to phospholipase C via a guanine nucleotide binding (G) protein. Receptor-mediated hydrolysis of PIP2 in PMN plasma membrane preparations requires both fMet-Leu-Phe and GTP, and incubation of intact PMNs with pertussis toxin (which ADP ribosylates and inactivates some G proteins) eliminates the ability of fMet-Leu-Phe plus GTP to promote PIP2 breakdown in isolated plasma membranes. Studies with both PMN particulate fractions and with partially purified fMet-Leu-Phe receptor preparations indicate that guanine nucleotides regulate CTX receptor affinity. Finally, fMet-Leu-Phe stimulates high-affinity binding of GTP gamma S to PMN membranes as well as GTPase activity. A G alpha subunit has been identified in phagocyte membranes which is different from other G alpha subunits on the basis of molecular weight and differential sensitivity to ribosylation by bacterial toxins. Thus, a novel G protein may be involved in coupling CTX receptors to phospholipase C. Studies in intact and sonicated PMNs demonstrate that metabolism of 1,4,5-IP3 proceeds via two distinct pathways: 1) sequential dephosphorylation to 1,4-IP2, 4-IP1 and inositol, or 2) ATP-dependent conversion to inositol 1,3,4,5-tetrakisphosphate (IP4) followed by sequential dephosphorylation to 1,3,4-IP3, 3,4-IP2, 3-IP1 and inositol. Receptor-mediated hydrolysis of PIP2 occurs at ambient intracellular Ca2+ levels; but metabolism of 1,4,5-IP3 via the IP4 pathway requires elevated cytosolic Ca2+ levels associated with cellular activation. Thus, the two pathways for 1,4,5-IP3 metabolism may serve different metabolic functions. Additionally, inositol phosphate production appears to be controlled by protein kinase C, as phorbol myristate acetate (PMA) abrogates PIP2 hydrolysis by interfering with the ability of the activated G protein to stimulate phospholipase C. This implies a physiologic mechanism for terminating biologic responses via protein kinase C mediated feedback inhibition of PIP2 hydrolysis.     

Metabolism and excretion of acetylchromenes by the migratory grasshopper

The extent of metabolism and excretion of three acetylchromenes (two toxic, one relatively nontoxic) were examined in adult migratory grasshoppers (Melanoplus sanguinipes) following topical administration. Both the total amount excreted (parent plus metabolites) and the proportion of parent compound in the excreta were inversely correlated with contact toxicity. Both toxic and nontoxic acetylchromenes are rapidly absorbed from the cuticle, with maximum excretion of parent and metabolite chromenes from 4 to 8 h posttreatment in each case. Much of the applied compounds (60–80%) apparently remains within the insect, and cannot be recovered by extraction of the insect. Metabolites formed result from simple oxidative and reductive transformations. For all of the compounds tested (including the allatocidin precocene II), the major mode of metabolism results from aliphatic hydroxylation of one of the geminal methyl groups on the chromene. No conjugated metabolites were found in the excreta.     

Influence of Physical Disruption on Growth of Attached Bacteria

Attached bacterial populations cultured without an exogenous carbon source or grown in conjunction with attached diatoms incorporated [³H]thymidine at a rate between four and five times lower than that of replicate bacterial populations which were dispersed before being assayed.     

Metabolism of the mutagen MeIQx in vivo: metabolite screening by liquid chromatography-thermospray mass spectrometry

2-Amino-3,8-dimethylimidazo(4,5-f)quinoxaline (MeIQx) is a potent mutagen found in cooked food. MeIQx and its isotopically labelled (13C, 15N2 and 14C) analogues were synthesised and used for metabolic studies in vivo. An equimolar mixture of MeIQx and its 13C, 15N2 stable isotope labelled analogue (containing tracer amounts of 14C-MeIQx) was given intraperitoneally to mice. Some 67% of the radioactivity was eliminated in urine and faeces within 24h. Four radiolabelled species were observed when urine was analysed by HPLC, corresponding to unchanged MeIQx and three more polar metabolites. Urine was analysed directly by HPLC-thermospray mass spectrometry. Four signals were observed containing the characteristic 1:1 isotopic doublet, corresponding to unchanged MeIQx, an MeIQx glucuronide, and two uncharacterized metabolites.     

Seasonal variation in diagnostic enzymes and biochemical constituents of captive northern bobwhites and passerines

1. A variety of biochemical measurements were taken periodically in captive northern bobwhite (Colinus virginianus L.), European starlings (Sturnus vulgaris L.), red-winged blackbirds (Agelaius phoeniceus L.) and common grackles (Quiscalus quiscula L.) to determine whether baseline values remain sufficiently stable throughout the year for general clinical use in the absence of concurrent control specimens. 2. Variables included whole blood hematocrit and hemoglobin, plasma lactate dehydrogenase, alpha-hydroxybutyrate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, creatine kinase, butyrylcholinesterase, alkaline phosphatase, glucose, albumin, total protein, creatinine, urea nitrogen, uric acid, cholesterol, and triglycerides, and brain acetylcholinesterase. Butyryl- and acetylcholinesterase were included because of their specific uses in toxicology. 3. Significant seasonal differences were detected for each of the variables except brain acetylcholinesterase in at least one of the species. Significant species differences were detected during at least one season for all of the variables measured. 4. All species were maintained outdoors, but only northern bobwhites came into reproductive condition and showed sex-differences in the clinical variables during their normal breeding season. 5. It was concluded that reference values for the 18 clinical variables measured could be calculated from our data for adult specimens of the species studied, and that results for one species cannot be extrapolated with certainty to any other species. 6. Estimated normal bounds for each of the 18 variables measured by commonly used clinical procedures are presented for reproductively quiescent northern bobwhites, European starlings, red-winged blackbirds, and common grackles.     

Germinal and non-germinal lines in the ovotestis of Helix aspersa: a survey

Summary The study of gonadal organogenesis and differentiation by means of light and electron microscopy suggested the following in Helix aspersa: (1) the distal parts of the acini have components of mesodermal origin, whereas the neck and efferent duct comprise ectodermal elements; (2) a segregation of a germinal line occurs early, during the embryonic life; (3) in juvenile and adult animals, male and female cells arise from a germinal ring located at the base of the acinar neck. Apart from developing oocytes, the epithelium lining the distal region of the acini consists of somatic cells (Sertoli and follicle cells).