Computed tomography and magnetic resonance imaging of the orbital apex

This article describes the CT and MR appearance of the orbital apex and masses in this region. The sectional anatomy by axial, coronal, and sagittal planes as well as the thin-layer technique used to accomplish this is detailed first. Then the application of these techniques to the presence of tumors is illustrated and discussed.

Endogenous forms of fibrinogen in Hep G2 cells

The three polypeptide chains of fibrinogen, A alpha, B beta and gamma chain, are synthesized on separate polysomes. Fully formed fibrinogen is a six chain, disulfide-linked, dimeric molecule with a molecular weight of 340kDa. Previous pulse-chase studies with L-35 S methionine using the human hepatocellular carcinoma cell line, Hep-G2, showed that the three chains are not immediately disulfide-linked and that there exist intermediate precursors as well as pools of A alpha and gamma chains (J. Biol. Chem. 259, 10574-10581, 1984). In this study the endogenous levels of fibrinogen and its precursors are measured by two different methods; pulse and steady-state labelling with L-35 S-methionine and immunoblotting. In Hep-G2 cells intracellular fibrinogen-related antigen is primarily (30-53%) composed of an A alpha-gamma complex and, to a smaller degree, of fully-formed fibrinogen (13-33%). Furthermore, the Hep G2 cell also contains endogenous pools of free gamma chain (11-26%). Other fibrinogen precursors (namely, the B beta-A alpha, B beta-gamma complexes as well as the fibrinogen half-molecule) do not appear to accumulate intracellularly. Most, if not all, of these precursors occur as isoforms but this heterogeneity is not due to varying degrees of glycosylation. In all the intracellular fibrinogen forms identified thus far, free sulfhydryl groups, detected by 14C-iodoacetamide incorporation, occur only in the A alpha-gamma complex and the free gamma chains.

Influence of passive smoking on admissions for respiratory illness in early childhood

An association was sought between passive smoking and inpatient admissions for respiratory illness in 1058 children born between 1 June and 31 December 1981 and living in the neighborhoods of Nan-Jing Western Road and Yan-An Western Road in Jing-An District, Shanghai. The admission rate for first episodes of respiratory illness was positively correlated with the total daily cigarette consumption of family members during the children's first 18 months of life. The relative risk of developing a first episode of respiratory illness was 1.80 for children living in families including people who smoked 10 or more cigarettes a day compared with those living in non-smoking families. Multiple logistic regression analysis showed that the effect of passive smoking on inpatient admission for respiratory illness was independent of the child's birth weight, type of feeding, father's education, size of the home, and chronic respiratory disease among adults in the family. The adjusted odds ratios compared with the non-smoking group were 1.17 in families smoking 1.9 cigarettes daily and 1.89 in families smoking 10 or more cigarettes daily. These data suggest that exposure to household cigarette smoke of children in early life increases the risk of severe respiratory illness.

Inhibitory effect in vitro of PR toxin, a mycotoxin from Penicillium roqueforti, on the mitochondrial HCO-3-ATPase of the rat brain, heart and kidney

The effects of PR toxin, a mycotoxin from Penicillium roqueforti, on the mitochondrial HCO3- -ATPase activity of the brain, heart and kidney from male Sprague-Dawley rats were determined by measuring colorimetrically the inorganic phosphate liberated by the ATPase in the presence or absence of bicarbonate ion. The IC50 (the concentration at which 50% of the enzyme activity is inhibited) of PR toxin on the mitochondrial HCO3- -ATPase from brain, heart and kidney were 12.7, 9.2 and 14.8 microM, respectively. The Michaelis-Menten constants (Km) of the enzyme from brain (1.1 mM), heart (1.5 mM) and kidney (2.3 mM) were not changed by PR toxin. Neither neutral nor anionic detergent increased the inhibitory potency of the toxin. It was concluded that of the three tissues tested, HCO3- -ATPase of the heart mitochondria was most sensitive to PR toxin, and that the toxin inhibited the HCO3- -ATPase in a non-competitive and irreversible manner.

Maternal diazepam exposure on brain ornithine decarboxylase and growth of offspring

The prenatal treatment of diazepam on the developmental pattern of brain ornithine decarboxylase and the general growth of offspring were studied. Diazepam (120 mg/kg/day) was administered orally to pregnant Sprague-Dawley rats from day 14 to day 20 of gestation. The activity of brain ornithine decarboxylase and body weight of the offspring were measured from the late fetal stage to the early postnatal stage. It was found that diazepam inhibited both the prenatal and 4-hour postnatal ornithine decarboxylase activities, though the general maturation pattern of the enzyme in the brain was not much altered. It may indicate that diazepam inhibits early brain development. The enzyme activity fell off as it reached maturation. Prenatal treated neonates of 6-hour or older age group had the normal activities of brain ornithine decarboxylase. The general growth of the treated offspring was substantially retarded. Their body weights were very much lower than the control offspring. The results of the present study is an additional evidence that diazepam and other benzodiazepines should be used with great care in pregnant women.

The effect of immunity on pulmonary metastasis of a methylcholanthrene-induced fibrosarcoma and three of its clones

A 3-Methylcholanthrene (MC)-induced fibrosarcoma and three of its clones were investigated for their metastatic potential in normal and tumor immune mice. The growth rates of the four tumors in vivo were similar. However, the mean survival times of the tumor-bearing mice were markedly different. Clone 10, the most immunogenic, showed very high metastatic potential and short survival, while clone 27, the least immunogenic, produced few metastases, resulting in much longer survival. Moderate numbers of metastases were produced by highly immunogenic 3-AM (parental tumor), and poorly immunogenic clone 34. Spleen cells from mice bearing highly immunogenic tumors lost their ability to neutralize tumors by day 28 after tumor inoculation, while those from mice bearing poorly immunogenic tumors remained cytotoxic, indicating that highly immunogenic tumors also induced immune suppression in the hosts. Immunization with specific tumors decreased the number of pulmonary metastases by 3 to 35-fold. Immunization with tumors that shared antigens provided protection against metastatic tumors as well as the local tumors. In contrast, immunization with antigenically different tumors gave no protection.

Fibrinogen precursors. Order of assembly of fibrinogen chains

Hep-G2 cells, incubated with L-[35S]methionine, incorporate radioactivity into fibrinogen and several fibrinogen-related compounds. Pulse-chase experiments indicate that several of these compounds are precursors of fibrinogen and that the cells contain intracellular pools of A alpha and gamma chains which participate in the assembly of fibrinogen. The rate of synthesis of the three component chains of fibrinogen is unequal with that of the B beta chain being less than that of the A alpha and gamma chains. The sequence of events which lead to the assembly of fibrinogen was deduced by determining the appearance of the radioactive chains in each of the fibrinogen precursors and in fibrinogen at various times during a pulse-chase incubation. Fibrinogen assembly commences while nascent incomplete B beta chains are attached at polysomes. Preformed A alpha and gamma chains, drawn from the intracellular pool, combine independently to the growing B beta chains. On completion of the nascent B beta chains, newly formed B beta-A alpha and B beta-gamma complexes are released from the polysomes and enter the luminal space of the endoplasmic reticulum. Later other A alpha and gamma chains are added by ordered disulfide interaction, leading to the eventual formation of dimeric fibrinogen.

Intracellular assembly of human fibrinogen

Hep-G2 cells, pulse-labeled with L-[35S]methionine, incorporate radioactivity within 2 min into precursor forms of fibrinogen and into fibrinogen. Pulse-labeled intracellular fibrinogen is first composed of radioactive B beta chains, followed by nascent A alpha chains. Radioactive gamma chains accumulate in the cells and later contribute, via intermediate forms, to the assembly of fibrinogen. Following a pulse-chase incubation with L-[35S]methionine, the radioactive composition of newly secreted fibrinogen also reflects the fact that there is a large intracellular pool of gamma chains.

A murine model of lip epidermal/mucosal reactions to X-irradiation

A new radiobiological test system has been developed for lip epidermal/mucosal reactions in mice. This is intended for use in investigations of the effect of non-standard fractionation and of modifying drugs on oral radiation reactions in human cancer patients. An arbitrary scale of scores was devised, with separate scores for oedema of the lips and for erythema or exudation. After single doses of 13-20 Gy, the mouse lip epidermal reactions began at 5 days, reached a peak about 10-13 days, and had fallen to low values, but not to zero, by 21 days. Several different periods for averaging the reaction scores were tested for relative steepness and variability, the most useful being 10-12 days inclusive or the 12th day score alone. The use of longer periods of averaging led to apparent saturation of the scores. It was found that large doses of X-rays repeated at 21-23 day intervals did not lead to escalating waves of reactions unless each dose was greater than 17 Gy. With these larger doses, escalation of reactions occurred even if the intervals were extended.

Bovine pulmonary surfactant: chemical composition and physical properties

Bovine pulmonary surfactant was obtained by endotracheal lavage of lungs from newly slaughtered cows followed by differential centrifugation. Lipid extracts of bovine surfactant contained 3% neutral lipid, mainly as cholesterol and diacylglycerol and 97% phospholipid. Phosphatidylcholine (79%) and phosphatidylglycerol (11%) accounted for most of the phospholipids with smaller amounts of phosphatidylethanolamine, phosphatidylinositol, lyso-bis-phosphatidic acid and sphingomyelin. Fatty acid analysis revealed high levels of palmitate in phosphatidylcholine and to a lesser extent phosphatidylglycerol, but not in the other diacylphospholipids. Phosphatidylcholine was 53% disaturated and phosphatidylglycerol was 23% disaturated. Monoenoic species accounted for the major proportion of the remaining lipid. The protein content was 10% as estimated by the Lowry procedure and 5% when determined by amino acid analysis. Extraction with chloroform/methanol removed ca. 90% of the protein but had no effect on the surfactant properties as evaluated by a pulsating bubble technique.

Secretion of proalbumin by canavanine-treated Hep-G2 cells

The two processing sites in the conversion of preproalbumin to albumin are marked by arginine residues. Therefore, to study the mechanisms of albumin processing and secretion, the arginine residues of nascent albumin were replaced with canavanine by the incubation of Hep-G2 cells with this arginine analog. During a 4-h interval, canavanine inhibited (67%) the secretion of nascent albumin and increased the intracellular transit time of albumin secretion from 24 to 39 min. At 1 h, canavanine inhibited total protein synthesis by 19% and albumin synthesis by about 40%. Both the intracellular and secreted albumin produced by canavanine-treated cells were analyzed by DEAE-cellulose chromatography and were found to be more acidic than normal proalbumin and albumin. Further analysis on sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that the albumin produced and secreted by canavanine-treated cells appeared to have a larger molecular weight (by 4000) than serum albumin. The canavanine-treated cells were incubated with L-[3H]leucine and L-[3H]phenylalanine and the location of radioactive L-leucine and L-phenylalanine in the 30 NH2-terminal amino acid residues of secreted albumin was determined. The results indicated that canavanine-treated cells secreted proalbumin (79%) and also some fully processed albumin (21%). Preproalbumin was not secreted. Untreated Hep-G2 cells mostly secreted fully processed serum albumin (93%) with only traces of proalbumin (7%).

The role of mRNA competition in regulating translation. III. Comparison of in vitro and in vivo results

Competition of encephalomyocarditis virus, reovirus, and L-cell mRNAs for a message-discriminatory component was studied in vitro. The data were analyzed qualitatively to determine the relative initiation efficiencies among the various mRNAs. The effects of potassium chloride concentration, magnesium acetate concentration, and m7G methylation on mRNA competition in vitro were also studied. These results were correlated with translation rates in vivo for the same mRNAs, to determine if the sites of competition in vitro and in vivo are the same. It was found that under a particular set of magnesium acetate and potassium chloride concentrations, the order of mRNA initiation efficiencies was the same both in vivo and in vitro, suggesting that the same limiting message-discriminatory factor is regulating initiation rates in both cases. This can only be accomplished in a competitive situation when RNA is in molar excess relative to the discriminatory component.

Site of synthesis of metallothionein in rat liver

Free and membrane-attached polysomes were isolated from the liver of normal and cadmium-treated rats, and were translated using L-[35S]cysteine and a nuclease-treated reticulocyte lysate system. The translation products were analyzed for radioactive metallothionein by immunoprecipitation with antibodies to rat cadmium metallothionein followed by sodium dodecyl sulfate--polyacrylamide gel electrophoresis. In both normal and cadmium-treated rats, radioactive metallothionein was produced by free polysomes but not by membrane-attached polysomes. Cadmium treatment did not increase the in vitro ability of polysomes to synthesize metallothionein. As a control, the translation products of these two classes of polysomes were also analyzed for radioactive albumin and it was confirmed that membrane-attached polysomes produce albumin but do not synthesize metallothionein. The cell-free synthesis of metallothionein by free polysomes was also demonstrated by isolation of nascent metallothionein by Sephadex gel filtration and DEAE-cellulose chromatography. In adult rat liver there are two forms of metallothionein and both were produced in vitro by free polysomes.

Effect of cyclophosphamide on mice bearing methylcholanthrene-induced fibrosarcomas

Mice bearing large methylcholanthrene-induced fibrosarcomas lost the ability to respond in vitro to mitogen stimulation and to specifically neutralize autologous tumor cells in vivo. This depressed immune capability was due to active suppression, since spleen cells from advanced tumor-bearing mice could suppress the mitogen response of normal spleen cells and could inhibit tumor rejection when adoptively transferred to mice previously immunized against the tumor. Treatment with cyclophosphamide (CY) was found to affect the immune capability of the host, in addition to have a direct effect on the tumor. The number of cells in the lymph nodes and spleen, as well as their response to concanavalin A and lipopolysaccharide (but not phytohemagglutinin), decreased initially but returned to normal by Day 14. Most importantly, when CY was administered one day after tumor inoculation, the treated animals developed the ability to neutralize tumor at the same time as untreated controls but retained this capability as the tumors became advanced. Treatment with a single dose of CY as late as 11 or 20 days after tumor inoculation maintained or restored the tumor-neutralizing capacity of spleen cells. CY appears to alter the antitumor response of the host by inhibiting both cytotoxic and suppressor cells, but the cytotoxic cells recover rapidly, whereas the suppressor cells do not.