The truncated form of the Epstein-Barr virus latent-infection membrane protein expressed in virus replication does not transform rodent fibroblasts

The gene encoding the Epstein-Barr virus membrane protein LMP, expressed in latent infection, is known to induce morphologic changes and some loss of contact inhibition in NIH 3T3 cells as well as profound loss of contact inhibition and of anchorage dependence in Rat-1 cells. Another form of LMP (D1LMP), deleted for the amino terminus and first four putative transmembrane domains of LMP, was recently shown to be expressed late in Epstein-Barr virus replication. We now demonstrate that D1LMP has no transformation-associated phenotypic effect in Rat-1 cells and does not significantly affect LMP-induced Rat-1 cell transformation. LMP activity and D1LMP inactivity in inducing anchorage-independent growth are not restricted to Rat-1 cells, but are also evident in BALB/c 3T3 cells. In both cell types, loss of contact inhibition and anchorage independence are acutely evident after LMP expression. Although newly transfected polyclonal Rat-1 or BALB/c cells have a lower agar cloning efficiency than established LMP-expressing clones, this is attributable, at least in part, to their lower average LMP expression, since among clones of transfected cells, higher cloning efficiencies correlated with higher levels of LMP. LMP is bound to the vimentin cytoskeletal network in rodent fibroblasts as it is in transformed lymphocytes, whereas D1LMP showed no detectable cytoskeletal binding, suggesting that cytoskeletal association may be integral to LMP-mediated cell transformation. LMP association with the cytoskeleton in latently infected, growth-transformed lymphocytes and LMP-transformed rodent fibroblasts, correlated with the lack of both rodent cell-transforming activity and cytoskeletal association of D1LMP supports working hypothesis that cytoskeletal association is important in LMP transforming activity.

Growth and water relations of seedlings of two subspecies of Eucalyptus globulus

Seedlings of Eucalyptus globulus Labill subsp. globulus grown in soil in pots in the greenhouse grew faster than seedlings of E. globulus subsp. bicostata, and responded better to added nutrients and water. However, water stress caused a greater reduction in the growth of shoots and roots, and in the root/shoot ratios of fertilized seedlings of subsp. globulus than in those of bicostata. More leaf surface wax was produced by seedlings grown in the presence of fertilizer and an adequate supply of water than by seedlings subjected to nutrient or water stress. Despite larger amounts of leaf surface wax, seedlings of subsp. bicostata had higher epidermal conductances than seedlings of subspecies globulus. However, epidermal conductances were reduced more by water stress and by fertilization in seedlings of subsp. bicostata than in subsp. globulus. Tissue osmotic potentials at full and zero turgor were reduced by water stress only in seedlings of subsp. bicostata and were increased by fertilizer only in seedlings of subsp. globulus. The results indicate that although seedlings of subsp. globulus have inherently higher growth rates, seedlings of subsp. bicostata are better adapted to drought.

Holographic real-time three-slit interferometer

A new and highly sensitive system, based on the three-slit interferometer, is described for the scanning measurement of optical path length differences over large objects. The system relieves the positional constraints of previous systems by separating the two lateral slits from the central slit using a double-exposure hologram. The lateral slit wavefronts are holographically reconstructed from an off-axis reference beam and added to light from the central slit to form a live intensity distribution pattern. Optical path length measurements can be made by comparing the magnitude of adjacent maxima as an object is translated across the central slit. The apparatus can be used for a number of practical applications including the measurement of flatness for an optical flat, thickness for transmissive or reflective films, and refractive-index differences of materials.

Aminophylline reduces air-flow-induced constriction in the canine lung periphery

We examined the effect of aminophylline on air-flow-induced constriction in the canine lung periphery. A wedged bronchoscope technique was used to measure airway wall temperature (Taw) and collateral resistance (Rcs) before and after air flow was increased from a baseline flow of 200 to 500, 1,000, 1,500, or 2,000 ml/min for 2-min periods. When a sublobar segment was challenged with dry air, Taw fell during the challenge (p less than 0.05) and Rcs increased 5 min postchallenge (p less than 0.01). Pretreatment with aminophylline (20 mg/kg) reduced the fall in Taw by 31% and reduced the increase in Rcs by 53%. Aminophylline did not significantly affect either the concentrations of PGD2, TxB2, and histamine or the cell numbers and profiles obtained by bronchoalveolar lavage performed 5 min postchallenge. However, trends were consistent with the decreased physiologic responses observed. Finally, aminophylline proved ineffective in reducing the constrictor response of peripheral lung challenged directly with aerosolized histamine or PGD2. Because preaminophylline and postaminophylline peripheral lung sensitivity (as assessed by the ratio delta Rcs/delta Taw) were not significantly different, we conclude that aminophylline attenuates physiologic responses by reducing the strength of the stimulus. Aminophylline could do this by facilitating the replacement of heat and water removed during dry air challenge by increasing bronchial or pulmonary blood flow, or by reducing heat and water loss via changes in mucosal permeability.

Mutagenicity and carcinogenicity studies of homemade "rust-proof cutting fluid"

A homemade rust-proof cutting fluid (RPCF) used in China was tested for carcinogenicity by an in vivo chronic experiment and for mutagenicity by the Ames Salmonella microsomal assay. Undiluted and threefold water-diluted fluid were given as drinking water to groups of young adult Wistar rats for 2 years. The treatment induced 11/40 malignant tumors with 9/40 acinar adenocarcinomas of the pancreas in the high-dose group. Simultaneous administration of ascorbic acid dissolved in the undiluted fluid at 2 g acid per 1 g sodium nitrite resulted in 1/40 pancreatic carcinoma. The results of the Ames test showed that the technical RPCF was mutagenic to TA100 with or without metabolic activation. It was concluded that the homemade RPCF, which is comprised of sodium nitrite, triethanolamine, and polyethylene glycol, may form direct-acting mutagen(s) upon storage and form, in vivo, e.g., nitrosamines that caused acinar pancreatic carcinoma in Wistar rats. Simultaneous administration of ascorbic acid is suggested for the protection of workers exposed to the rust-proof cutting fluid.

Enhancement of neutrophil superoxide production by preincubation with recombinant human tumor necrosis factor

Tumor necrosis factor (TNF) is a 17,000-Da protein which is produced by mononuclear cells upon exposure to endotoxin. Increases in adherence, phagocytosis, hydrogen peroxide release, and lysozyme secretion have been demonstrated after prolonged incubation of human neutrophils with TNF. In this study, the ability of highly purified recombinant human TNF to modulate neutrophil responses to soluble stimuli was evaluated. Tumor necrosis factor alone (0.1 to 10,000 units/ml) failed to induce neutrophil superoxide anion (O2-) production, granule release, or aggregation when incubated for up to 25 min at 37 degrees C. TNF did, however, stimulate a significant time-, dose-, and temperature-dependent increase in neutrophil F-actin content. Although exposure of neutrophils to TNF alone caused no superoxide anion production, it enhanced the O2- production in response to the chemotactic peptide, f-methionyl-leucyl-phenylalanine (FMLP) or the tumor promotor, phorbol myristate acetate, by as much as 278%. The enhancement was time-, dose-, and temperature-dependent and was due to a more rapid initial rate of O2- production. The TNF enhancement of FMLP-induced O2- production was blocked when an anti-TNF monoclonal antibody 241-1H11, is present during the preincubation period. TNF preincubation also enhanced FMLP-induced lysozyme release, but had no effect on aggregation and actin polymerization by FMLP. The kinetics of NADPH oxidase activation by arachidonic acid was unaltered by TNF. These results indicate that brief exposures to recombinant human TNF are able to enhance or prime the neutrophil oxidative burst in response to a second stimulus.

Enhancement of neutrophil superoxide production by preincubation with recombinant human tumor necrosis factor

Tumor necrosis factor (TNF) is a 17,000-Da protein which is produced by mononuclear cells upon exposure to endotoxin. Increases in adherence, phagocytosis, hydrogen peroxide release, and lysozyme secretion have been demonstrated after prolonged incubation of human neutrophils with TNF. In this study, the ability of highly purified recombinant human TNF to modulate neutrophil responses to soluble stimuli was evaluated. Tumor necrosis factor alone (0.1 to 10,000 units/ml) failed to induce neutrophil superoxide anion (O2-) production, granule release, or aggregation when incubated for up to 25 min at 37 degrees C. TNF did, however, stimulate a significant time-, dose-, and temperature-dependent increase in neutrophil F-actin content. Although exposure of neutrophils to TNF alone caused no superoxide anion production, it enhanced the O2- production in response to the chemotactic peptide, f-methionyl-leucyl-phenylalanine (FMLP) or the tumor promotor, phorbol myristate acetate, by as much as 278%. The enhancement was time-, dose-, and temperature-dependent and was due to a more rapid initial rate of O2- production. The TNF enhancement of FMLP-induced O2- production was blocked when an anti-TNF monoclonal antibody 241-1H11, is present during the preincubation period. TNF preincubation also enhanced FMLP-induced lysozyme release, but had no effect on aggregation and actin polymerization by FMLP. The kinetics of NADPH oxidase activation by arachidonic acid was unaltered by TNF. These results indicate that brief exposures to recombinant human TNF are able to enhance or prime the neutrophil oxidative burst in response to a second stimulus.

Effect of tryptophan on isolated hepatocytes of rats

The addition of tryptophan to adult rat hepatocyte cultures stimulated DNA synthesis. The increase in DNA synthesis as measured by 3H-thymidine incorporation into DNA was observed on treatment of the cultures with tryptophan for 48 h but also as short as for 6 h in comparison with control cultures. An increase was also apparent at 30 h which was maintained for up to 48 h post treatment with tryptophan. The increase in DNA synthesis by tryptophan cannot be attributed to cell injury or to increased DNA degradation. Of the degradative enzymes added after harvesting the hepatocytes, only DNase decreased incorporation of 3H-thymidine. The observed effect was specific for tryptophan since treatment with kynurenine, isoleucine, methionine or serine failed to show a significant effect. Pretreatment of cultured hepatocytes with hydroxyurea prevented the tryptophan stimulated increase in DNA synthesis suggesting that the latter was due to replicative and not to reparative DNA synthesis. Experiments performed with the addition of diethylnitrosamine also alluded to tryptophan's role in replicative DNA synthesis. The mechanism of tryptophan-induced DNA synthesis is discussed.

Influence of level of dietary protein on tryptophan-induced promotional activity in induction of gamma-glutamyl transpeptidase-positive foci of rat liver

The influence of varying the dietary protein content on the emergence of gamma-glutamyl transpeptidase (GGT)-positive foci in the livers of male rats fed elevated (2%) L-tryptophan (TRP) after being exposed to a hepatocarcinogen was investigated. Subtotal hepatectomies were performed, and 18 hr later the rats were treated with diethylnitrosamine (30 mg/kg). Ten days later four dietary groups were followed for 10 weeks: (1) control diet containing 21% protein (C); (2) control diet containing 5.3% protein (C-LP); (3) C + TRP; and (4) C-LP + TRP. Rats fed the C-LP diet developed heavier livers but fewer and smaller GGT + foci than did rats fed the C diet. Rats fed elevated TRP diets (C + TRP and C-LP + TRP) developed more and larger GGT + foci than did rats fed the regular control diets (C and C-LP), indicating that the promotional effect of elevated dietary TRP was similar at the two levels of dietary protein.

Evidence for active half-molecules of alpha 2-macroglobulin formed by dissociation in urea

Urea caused dissociation of alpha 2-macroglobulin (alpha 2M) into half-molecules (two disulfide-bonded subunits) as revealed by gel electrophoresis. The fraction of whole molecules remaining decreased with increasing urea concentration. Half-dissociation occurred at about 2.2 M. The ability of alpha 2M to inhibit trypsin also decreased with increasing urea concentration, but the activity-urea curve was shifted to the right as compared to the dissociation-urea curve. Thus, at 3 M urea, gel electrophoresis showed only 6.6% whole molecules, whereas the trypsin inhibitory activity was 95% of that in buffer with no urea, suggesting that half-molecules retain activity. In addition, complexes formed in urea with 125I-labeled trypsin were observed to migrate as half-molecules even though only 50% of such complexes were covalent. These results are surprising in light of the report by Gonias and Pizzo [Gonias, S., & Pizzo, S. (1983) Biochemistry 22, 536-546] that half-molecules formed by mild reduction are active; reduction is assumed to divide the molecule along an axis orthogonal to the break caused by urea. This suggests that active half-molecules can be formed by splitting either the covalent or noncovalent bonds that hold the subunits together. A model is proposed that can account for this possibility. It has the same dimensions and symmetry as a previous model of Feldman et al. [Feldman, S.R., Gonias, S.L., & Pizzo, S.V. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 5700-5704] and accounts in a similar way for previous functional studies of the protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Recognition of EBV plasma membrane protein expressed on murine cells after gene transfer

The immune response to B lymphocytes infected with Epstein-Barr virus (EBV) prevents their overgrowth in normal humans. A murine model is now described for analyzing the T cell immune response to Epstein-Barr virus genes expressed in murine lymphoblasts by gene transfer. In mice, a 60,000 dalton virus-encoded protein characteristically found in the plasma membrane of latently infected human lymphocytes readily induces both proliferative and cytolytic T lymphocytes specific for both the EBV protein and murine major histocompatibility proteins. Longterm cultures of L3T4+ cells, some of which were cytolytic, were found to be restricted by H-2I-Ed and the latent membrane protein. Similarly, Lyt-2+ cells were cytolytic and were restricted by H-2Ld and the lymphocyte membrane protein gene product. The similarity in murine and human effector cell responses suggests that this is a useful experimental model, and the EBV latent infection membrane protein may be an important antigen in the immune restriction of growth transformed latently infected lymphocytes.

Recognition of EBV plasma membrane protein expressed on murine cells after gene transfer

The immune response to B lymphocytes infected with Epstein-Barr virus (EBV) prevents their overgrowth in normal humans. A murine model is now described for analyzing the T cell immune response to Epstein-Barr virus genes expressed in murine lymphoblasts by gene transfer. In mice, a 60,000 dalton virus-encoded protein characteristically found in the plasma membrane of latently infected human lymphocytes readily induces both proliferative and cytolytic T lymphocytes specific for both the EBV protein and murine major histocompatibility proteins. Longterm cultures of L3T4+ cells, some of which were cytolytic, were found to be restricted by H-2I-Ed and the latent membrane protein. Similarly, Lyt-2+ cells were cytolytic and were restricted by H-2Ld and the lymphocyte membrane protein gene product. The similarity in murine and human effector cell responses suggests that this is a useful experimental model, and the EBV latent infection membrane protein may be an important antigen in the immune restriction of growth transformed latently infected lymphocytes.

Epitope mapping of functional domains of human factor Va with human and murine monoclonal antibodies. Evidence for the interaction of heavy chain with factor Xa and calcium

We have purified a unique neutralizing IgG1, kappa monoclonal antibody (MAb) against factor V (F-V) from a patient's plasma. This MAb (H2) demonstrated specificity for human F-V heavy chain (D), mol wt 105,000. Using an enzyme-linked immunosorbent assay (ELISA) we assessed the competitive binding to F-Va of H2, H1 (human MAb directed to light chain, F1F2), and two murine MAbs, B38 (to F1F2) and B10 (to activation peptide C1). All four antibodies are of high affinity with KD varying from 0.17 to 1.17 X 10(-10) mol/L. They recognized distinct epitopes in F-V. F-Xa competed in a concentration-dependent fashion for binding of H1, H2, and B38 but not B10 to F-V/Va in the absence of phospholipids or platelets. Thus both F1F2 and D polypeptides of F-Va but not C1 interacted with F-Xa. All MAbs bound to F-V/Va in the absence of Ca++. However, free Ca++ (0.1 to 4.0 mmol/L) increased the amount of H1 and H2 bound to factor V/Va, 1.65-fold and 3.65-fold, respectively but had little effect on the binding of either murine MAbs. Prothrombin (20 micrograms/mL to 400 micrograms/mL) in the absence of phospholipid did not inhibit the binding of MAbs. These studies provide evidence for the first time for a direct interaction between human F-Va heavy chain and F-Xa and Ca++ and for the direct binding of F-Xa to F-Va in the absence of phospholipids or platelets and enhance our understanding of functional F-V domains.

Effects of neutrophils on collateral ventilation and peripheral lung reactivity in dogs

We studied the effects of neutrophil activation on collateral ventilation and peripheral lung reactivity in anesthetized dogs. A fiberoptic bronchoscope was wedged into a segmental airway under direct vision. Ventilation beyond the obstruction thus occurred only through collateral channels. Through one lumen of a double-lumen catheter threaded through the suction port of a bronchoscope, 5% CO2 in air was infused at a known constant rate (V coll). Through the other lumen, pressure at the tip of the bronchoscope was monitored (Pb). For measurements of resistance to flow through the collateral system (Rcs), the ventilation was stopped at functional residual capacity (FRC). Histamine was delivered through the bronchoscope to the obstructed lung segment in the form of an aerosol mist generated by an ultrasonic nebulizer. Measurements of Rcs were used as a parameter of the peripheral lung reactivity to histamine challenge. Within one hour after intravenous infusion of phorbol myristate acetate (PMA), a neutrophil activator, the reactivity to histamine significantly increased. After this, Rcs increased even without histamine challenge. This increase may have been due to an edematous injury of lung caused by PMA. The nature of the injury was confirmed by wet to dry weight ratios. In the other group, the white cell count dropped below 1000 per cu. mm. after intravenous infusion of nitrogen mustard. The same experimental protocols were followed. The Rcs did not increase even with histamine challenge. Our results suggested that substances such as oxygen radicals and arachidonic acid metabolites, which can be released by activated neutrophils, may not not only increase peripheral lung reactivity, but may also induce pulmonary edema.

Dry air-induced constriction: effects of pharmacological intervention and temperature

We studied airway wall temperature (Taw) during dry air challenge of the canine lung periphery. We measured collateral resistance (Rcs) before and after periods of elevated airflow using a wedged bronchoscope technique. As flow rate increased, Taw dropped and postchallenge Rcs rose. A significant negative correlation was found between Taw recorded during challenge and Rcs observed 5 min after challenge. Repetitive dry air challenge produced similar changes in Rcs and Taw. However, responses to warm moist air were significantly lower than consecutive responses to dry air. Taw was significantly lower during dry air challenge than during moist air challenge. Indomethacin (5 mg/kg) and atropine (1 mg/kg) reduced responses to dry airflow challenge. Indomethacin did not affect Taw during the challenge, whereas atropine reduced the fall in Taw. We conclude that temperature correlates negatively with peripheral lung tone 5 min after dry air challenge. This correlation holds under conditions where airflow is increased, air is humidified, or atropine is administered. The dissociation between Taw and physiological response after indomethacin likely reflects a decrease in mediators released during challenge.

Calcium ionophore, phorbol ester, and chemotactic peptide-induced cytoskeleton reorganization in human neutrophils

Formyl-methionylleucylphenylalanine (fMLP) activation of neutrophils causes an increase in intracellular Ca2+, activation of protein kinase C and an increase in F-actin content. To examine the role of Ca2+ and protein kinase C activation as determinants of change in F-actin content of neutrophils, we used the NBD-phallacidin extraction assay to compare the kinetics and extent of change in F-actin content of cells activated with fMLP, the calcium ionophore A23187 or phorbol myristate acetate (PMA). All stimuli increase the F-actin content in a dose-dependent manner; however, the rate of increase is slower and the maximum F-actin content is less for calcium ionophore and PMA than for fMLP-activated cells. The A23187-induced increase in F-actin content, but not that of fMLP, depends upon external free [Ca2+]. In A23187-activated cells, F-actin content increases at [Ca2+]free greater than or equal to 5 microM, is maximal at [Ca2+]free greater than or equal to 10 microM and is negligible at physiologic free [Ca2+] (10(-7)-10(-6) M). Combinations of PMA with A23187 or fMLP inhibit the A23187, but not the fMLP, activated actin polymerization. Comparison and combination of these activators shows that neither Ca2+-dependent activation with A23187 nor activation with PMA alone or in combination mimic the fMLP-induced changes in cytoskeleton organization of neutrophils.

Epstein-Barr virus nuclear antigen 2 specifically induces expression of the B-cell activation antigen CD23

Epstein-Barr virus (EBV) infection of EBV-negative Burkitt lymphoma (BL) cells induces some changes similar to those seen in normal B lymphocytes that have been growth transformed by EBV. The role of individual EBV genes in this process was evaluated by introducing each of the viral genes that are normally expressed in EBV growth-transformed and latently infected lymphoblasts into an EBV-negative BL cell line, using recombinant retrovirus-mediated transfer. Clones of cells were derived that stably express the EBV nuclear antigen 1 (EBNA-1), EBNA-2, EBNA-3, EBNA-leader protein, or EBV latent membrane protein (LMP). These were compared with control clones infected with the retrovirus vector. All 10 clones converted to EBNA-2 expression differed from control clones or clones expressing other EBV proteins by growth in tight clumps and by markedly increased expression of one particular surface marker of B-cell activation, CD23. Other activation antigens were unaffected by EBNA-2 expression, as were markers already expressed on the parent BL cell line, including BL markers (cALLA and BLA), proliferation markers (transferrin receptor and BK19.9), and cell adhesion-related molecules (LFA-1 and LFA-3). Increased CD23 expression in cells expressing EBNA-2 was apparent from monoclonal anti-CD23 antibody binding to the cell surface, from immunoprecipitation of the 45-kDa and 90-kDa CD23 proteins with monoclonal antibody, and from RNA blots probed with labeled CD23 DNA. The results indicate that EBNA-2 is a specific direct or indirect trans-activator of CD23. This establishes a link between an EBV gene and cell gene expression. Since CD23 has been implicated in the transduction of B-cell growth signals, its specific induction by EBNA-2 could be important in EBV induction of B-lymphocyte transformation.

The mammalian beta-tubulin repertoire: hematopoietic expression of a novel, heterologous beta-tubulin isotype

We describe the structure of a novel and unusually heterologous beta-tubulin isotype (M beta 1) isolated from a mouse bone marrow cDNA library, and a second isotype (M beta 3) isolated from a mouse testis cDNA library. Comparison of M beta 1 and M beta 3 with the completed (M beta 4, M beta 5) or extended (M beta 2) sequence of three previously described beta-tubulin isotypes shows that each includes a distinctive carboxy-terminal region, in addition to multiple amino acid substitutions throughout the polypeptide chain. In every case where a mammalian interspecies comparison can be made, both the carboxy-terminal and internal amino acid substitutions that distinguish one isotype from another are absolutely conserved. We conclude that these characteristic differences are important in determining functional distinctions between different kinds of microtubule. The amino acid homologies between M beta 2, M beta 3, M beta 4, and M beta 5 are in the range of 95-97%; however the homology between M beta 1 and all the other isotypes is very much less (78%). The dramatic divergence in M beta 1 is due to multiple changes that occur throughout the polypeptide chain. The overall level of expression of M beta 1 is low, and is restricted to those tissues (bone marrow, spleen, developing liver and lung) that are active in hematopoiesis in the mouse. We predict that the M beta 1 isotype is functionally specialized for assembly into the mammalian marginal band.

Dynamic changes of lung lymph flow and the release of lysosomal enzyme from the lungs after severe steam inhalation injury in goats

Chronic lung lymph fistulae were produced in six goats according to Winn's and Stothert's methods with our modification to define the pathophysiology of pulmonary oedema after severe steam inhalation injury. Arterial blood gas, lung lymph flow (QLym), lymph/plasma total protein concentration ratio (L/P), and beta-glucuronidase (beta-G) in plasma and lung lymph were monitored for 24 h post-injury. The pathological changes in the lung tissues were also determined at the end of the study. It was found that directly after injury, QLym increased steadily to a peak value at 6 h, followed by declining values at 18 and 24 h. L/P decreased promptly during the 60 min after injury and then also steadily increased to a peak value at 4 h (P less than 0.05). A significant increase in plasma beta-G was only observed at 4 h post-burn. However, lung lymph beta-G activities and lymph beta-G transport increased immediately after injury, reaching a peak at 4 h (5 and 12 times above baseline values, respectively, P less than 0.01). Significant hypoxaemia and hypocapnia occurred at 2 h post-burn and deteriorated progressively throughout the study. There were obvious pulmonary interstitial and alveolar oedema microscopically. This study demonstrates that the increase in transvascular fluid and protein flux after steam inhalation injury is mainly due to increased pulmonary microvascular permeability. Nevertheless, a hydrostatic pressure effect can not be completely excluded, especially in the first hour post-burn. Lysosomal enzyme release is considered to be one of the important factors which damage lung microvascular elements and induce an increase in their permeability.

Six mouse alpha-tubulin mRNAs encode five distinct isotypes: testis-specific expression of two sister genes

Five mouse alpha-tubulin isotypes are described, each distinguished by the presence of unique amino acid substitutions within the coding region. Most, though not all of these isotype-specific amino acids, are clustered at the carboxy terminus. One of the alpha-tubulin isotypes described is expressed exclusively in testis and is encoded by two closely related genes (M alpha 3 and M alpha 7) which have homologous 3' untranslated regions but which differ at multiple third codon positions and in their 5' untranslated regions. We show that a subfamily of alpha-tubulin genes encoding the same testis-specific isotype also exists in humans. Thus, we conclude that the duplication event leading to a pair of genes encoding a testis-specific alpha-tubulin isotype predated the mammalian radiation, and both members of the duplicated sequence have been maintained since species divergence. A second alpha-tubulin gene, M alpha 6, is expressed ubiquitously at a low level, whereas a third gene, M alpha 4, is unique in that it does not encode a carboxy-terminal tyrosine residue. This gene yields two transcripts: a 1.8-kilobase (kb) mRNA that is abundant in muscle and a 2.4-kb mRNA that is abundant in testis. Whereas the 1.8-kb mRNA encodes a distinct alpha-tubulin isotype, the 2.4-kb mRNA is defective in that the methionine residue required for translational initiation is missing. Patterns of developmental expression of the various alpha-tubulin isotypes are presented. Our data support the view that individual tubulin isotypes are capable of conferring functional specificity on different kinds of microtubules.

Phagocytosis of different matrix components by different cell types at bone-forming sites in cultured mouse calvariae

Sites of bone formation on fragments of parietal bone of fetal-mice cultured for 10 days were examined by electron microscopy after addition of either ruthenium red or ferrocyanide to the postfixation fluid. Osteoclasts, osteoblast-like cells, and macrophages were the principal active cells at these formation sites. The mononuclear cells (osteoblast-like cells and macrophages) in the osteoid tissue showed evidence of having incorporated elements of calcified tissue. Osteoblast-like cells had phagocytized collagen fibrils and calcified bone matrix. This occurred more frequently in the calcifying area. Mononuclear macrophages showed not only phagocytosis and digestion of cellular debris and bone spicules in the osteoid, but also active incorporation of calcified bone matrix that had been detached from its surroundings by its pseudopod-like projections from long cytoplasmic processes. Collagen fibrils were seldom observed within the macrophages. These observations suggest that in our culture system osteoblast-like cells and macrophages at bone formation sites have a phagocytic role in bone remodeling.

Effects of varying fat content of a high tryptophan diet on the induction of gamma-glutamyltranspeptidase positive foci in the livers of rats treated with hepatocarcinogen

The influence of varying the dietary fat content on the emergence of gamma-glutamyltranspeptidase (GGT)-positive foci in the livers of male rats fed elevated (2%) L-tryptophan (TRP) and exposed to a hepatocarcinogen was investigated. Subtotal hepatectomies were performed, and 18 h later the rats were treated with diethylnitrosamine (DEN) (30 mg/kg). Ten days later 4 dietary groups were followed for 10 weeks: (1) control diet containing 15% fat (C-HF); (2) control diet containing 5% fat (C-LF); (3) C-HF + TRP; (4) C-LF + TRP. Rats fed elevated TRP diets (C-HF + TRP and C-LF + TRP) similarly developed more and larger GGT+ foci than did rats fed the regular TRP diets (C-HF and C-LF), indicating that the promotional effect of elevated dietary TRP was not affected by the fat level (15% vs. 5%).

Orientation and patching of the latent infection membrane protein encoded by Epstein-Barr virus

Epstein-Barr virus is known to encode three nuclear proteins and one membrane protein (LMP) in latently infected growth-transformed cells. Studies of the plasma membrane localization and orientation of LMP by protease digestion of live cells and by immunofluorescence indicated the following. (i) At least 30% of LMP is in the plasma membrane, as opposed to other cytoplasmic membranes. (ii) A small LMP domain which corresponds to a previously proposed outer reverse turn between the first two transmembrane domains is exposed on the outer cell surface (and two other proposed outer-reverse-turn domains may be exposed), whereas all or almost all of the rest of the protein is not exposed on the outer cell surface. (iii) LMP is present in patches in the cell plasma membrane.

Involvement of developing sympathetic nervous system in thyroxine-mediated submandibular gland nerve growth factor and epidermal growth factor responses

Thyroxine (T4) administration in mice during the 2nd wk of postnatal life elicits a precocious increase in submandibular gland-nerve growth factor (SMG-NGF) and epidermal growth factor (SMG-EGF) levels, but the mechanism(s) of T4 action has not been studied. The present report examines the role of the developing sympathetic nervous system (SNS) in the SMG-NGF and EGF responses to T4. For this purpose newborn mice were injected with T4 and/or 6-hydroxydopamine, a toxic congener of norephinephrine which causes selective destruction of sympathetic nerve terminals. The effectiveness of chemical sympathectomy was assessed by SMG-norepinephrine measurements using a sensitive radioenzymatic assay. The glandular norepinephrine contents were greatly reduced indicating that the dose and duration of 6-OHDA treatment were sufficient to cause a total sympathectomy in SMG tissue. In addition, the 6-OHDA treatment greatly reduced the wet weight and total protein content of the sympathetic superior cervical ganglia which innervate SMG tissue. SMG-NGF and EGF concentrations were measured by specific radioimmunoassays. 6-OHDA treatment alone did not affect the basal SMG-NGF and EGF concentrations. However, the maximal responses of SMG-NGF and EGF to T4 administration were greatly reduced by concurrent treatment with 6-OHDA. In summary, the data demonstrate a critical role for developing sympathetic nervous system in the T4-stimulated increase in SMG-NGF and EGF concentrations.

Lung vascular injury after Escherichia coli endotoxin and phorbol myristate acetate infusion in dogs

The effects of Escherichia coli endotoxin and phorbol myristate acetate (PMA), a potential stimulator of polymorphonuclear leukocyte (PMN), on circulating PMN counts, gas exchange, protein concentration of lavage fluid, pulmonary hemodynamics and pathology of the lung were studied in ten anesthetized dogs. Six dogs were infused with 1 microgram/kg endotoxin plus 10 micrograms/kg of PMA; four other dogs were infused with the same amount of endotoxin but 5 micrograms/kg of PMA. After administration of endotoxin plus 10 micrograms/kg PMA, the number of circulating PMN (per mm3) decreased dramatically from 4081 +/- 1041 to 303 +/- 119, arterial oxygen partial pressure (PaO2) dropped to 49.1 +/- 2.4 mmHg and the arterial alveolar oxygen partial pressure difference (A-a DO2) increased significantly above baseline. Lungs from this group appeared to be grossly damaged: edema with distinct petechial hemorrhage and areas of hemorrhagic consolidation; frothy edema fluid often emanated from the tracheas. The group infused with endotoxin plus 5 micrograms/kg PMA showed no significant decrease in the number of PMN; PaO2 and A-a DO2 maintained comparatively stable. Protein concentration of lavage fluid and lung wet/dry weight ratios in dogs of 10 micrograms/kg PMA group were significantly increased (P less than 0.05) as compared to those of 5 micrograms/kg PMA group. Our study showed that the magnitude of leukopenia after endotoxin and PMA was paralleled with the severity of lung vascular injury. These results support the potential role of PMN in the pathogenesis of acute edematous lung injury.

Protective effect of tryptophan and cysteine against carbon tetrachloride-induced liver injury

The effects of the administration of tryptophan and/or cysteine on carbon tetrachloride (CCl4)-induced hepatic injury were investigated. Rats received CCl4 (1 ml/kg ip) followed 6 hr later by tryptophan (300 mg/kg) and/or cysteine (950 mg/kg) via stomach tube and rats were killed after 24 hr. Treatment with tryptophan, cysteine, or both reduced the degree of hepatic necrosis observed histologically. While CCl4 caused polyribosomal disaggregation and decreased [14C]leucine incorporation into liver proteins in vitro and in vivo, treatment with tryptophan, cysteine, or both caused a shift in polyribosomes toward heavier aggregation and protein synthesis was increased. Serum activities of lactic dehydrogenase (LDH), glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, and gamma-glutamyl-transpeptidase were markedly increased after CCl4 alone but after subsequent treatment with cysteine or with tryptophan and cysteine appreciable decreases occurred. Glutathione concentration decreased but total amount remained constant in the livers of CCl4-treated rats while subsequent treatment with cysteine alone or together with tryptophan elevated both levels of glutathione. Using isolated hepatocytes, CCl4 caused decreases in cell viability, in release of LDH, and in [14C]leucine incorporation into protein. Treatment with CCl4 and tryptophan and/or cysteine revealed that cysteine alone or with tryptophan improved cell viability and decreased LDH release of the cells, while tryptophan alone or with cysteine improved protein synthesis. Upon cytologic evaluation, the isolated hepatocytes revealed membrane distortions after CCl4 alone but these were less marked after CCl4 plus tryptophan, cysteine, or both (most improvement). Thus, tryptophan and cysteine act in a beneficial manner against CCl4-induced hepatic injury in the rat.

An EBV membrane protein expressed in immortalized lymphocytes transforms established rodent cells

Epstein-Barr virus expresses a cytoplasmic and plasma membrane protein (LMP) in latently infected growth transformed lymphocytes. The gene specifying LMP has now been expressed in NIH3T3 and Rat-1 cells. Expression of the gene in these cells resulted in altered cell morphology and some resistance to the growth inhibiting effect of medium containing low serum. In Rat-1 cells, LMP expression often led to loss of contact inhibition and anchorage-independent growth in soft agar. Rat-1 cells expressing LMP were uniformly tumorigenic in nude mice. Thus, LMP is a transforming gene which is likely to account for many aspects of EBV induced cell transformations. This is the first demonstration of a transforming gene in Epstein-Barr virus, a ubiquitous human pathogen associated with neoplasia.

Bovine chymotrypsinogen A X-ray crystal structure analysis and refinement of a new crystal form at 1.8 A resolution

The X-ray structure of a new crystal form of chymotrypsinogen A grown from ethanol/water has been determined at 1.8 A resolution using Patterson search techniques. The crystals are of orthorhombic space group P212121 and contain two molecules in the asymmetric unit. Both independent molecules (referred to as A and B) have been crystallographically refined to a final R value of 0.173 with reflection data to 1.8 A resolution. Owing to different crystal contacts, both independent molecules show at various sites conformational differences, especially in segments 33-38, 142-153 and 215-222. If these three loops are omitted in a comparison, the root-mean-square (r.m.s.) deviation of the main-chain atoms of molecules A and B is 0.32 A. If segments 70-79, 143-152 and 215-221 are omitted, a comparison of either molecule A or molecule B with the chymotrypsinogen model of Freer et al. (1970) reveals an r.m.s. deviation of the alpha-carbon atoms of about 0.7 A. Compared with the active enzyme, four spatially adjacent peptide segments, in particular, are differently organized in the zymogen: the amino-terminal segment 11-19 runs in a rigid but strained conformation along the molecular surface due to the covalent linkage through Cys1; also segment 184-194 is in a rigid unique conformation due to several mutually stabilizing interactions with the amino-terminal segment; segment 216-222, which also lines the specificity pocket, adapts to different crystal contacts and exists in both chymotrypsinogen molecules in different, but defined conformations; in particular, disulfide bridge 191-220, which covalently links both latter segments, has opposite handedness in molecules A and B; finally, the autolysis loop 142 to 153 is organized in a variety of ways and in its terminal part is completely disordered. Thus, the allosteric activation domain (Huber & Bode, 1978) is organized in defined although different conformations in chymotrypsinogen molecules A and B, in contrast to trypsinogen, where all four homologous segments of the activation domain are disordered. This reflects the structural variability and deformability of the activation domain in serine proteinase proenzymes. If the aforementioned peptide segments are omitted, a comparison of our chymotrypsinogen models with gamma-chymotrypsin (Cohen et al., 1981) yields an r.m.s. deviation for alpha-carbon atoms of about 0.5 A. The residues of the "active site triad" are arranged similarly, but the oxyanion hole is lacking in chymotrypsinogen.(ABSTRACT TRUNCATED AT 400 WORDS)

Detection of the tumour-associated antigens recognized by the monoclonal antibodies HMFG-1 and 2 in serum from patients with breast cancer

The levels of the human milk fat globule 1 and 2 antigens have been measured in the sera of patients with advanced breast cancer, using a "sandwich" type radioimmune assay which exploits the carbohydrate nature of the antigenic determinants. In the series studied, 30% of sera from advanced breast cancer patients contained elevated levels of the HMFG-I antigen as compared with 6% of sera from healthy control women, whereas 53% of the advanced breast cancer patients showed elevated levels of HMFG-2 antigen compared with 16,6% of the controls. By means of the immune blotting technique, the components carrying the antigenic determinants in sera have been identified and compared for size with those molecules expressing the determinants in primary and secondary breast tumours. Both antibodies react with similar molecular weight components of 320kd and 280kd which are present in serum and tumour samples, although lower molecular weight bands of 230kd and 190kd can be seen in some tumours. These components are much smaller than the glycoprotein (greater than 400kd) present in the human milk fat globule, which carries the antigenic determinants recognized by HMFG-I and 2.

Investigation of cancer epidemiology and study of carcinogenic agents in the Shanghai Rubber Industry

Preliminary studies on crude cancer incidences among workers from 89 factories in Shanghai revealed excessive risk of cancer for workers in certain workshops of rubber tire factories. Chronic in situ animal exposures showed that compounding and Banbury mills for mastication and mixing were origins of carcinogenic contaminants. Various chronic experiments indicated the carcinogenicity of PBNA in rats and mice, especially with regard to the lungs. The high concentration of PBNA in the atmosphere of the work area seemed to be related to the excessive incidence of lung cancer among the workers. Epidemiological investigation showed that there was an excessive number of cases of lung cancer in the workshop of rubber tire factories where compounding, mixing, and milling took place.

Carcinogenicity of N-phenyl-1-naphthylamine and N-phenyl-2-naphthylamine in mice

Technical N-phenyl-1-naphthylamine ( PANA ), which is an optic isomer of N-phenyl-2-naphthylamine ( PBNA ), has been used as a rubber additive without suspicion of its being carcinogenic. When male ICR mice were given repeated s.c. injections of both technical and pure PANA in dimethyl sulfoxide, it resulted in high percentage of malignant tumors similar to that in mice given technical PBNA . PANA had a tendency to induce hemangiosarcoma. Similar injections of PANA and PBNA into male TA-1 mice gave similar results. Previous unilateral nephrectomy enhanced both PANA and PBNA induction of renal hemangiosarcomas. The similar carcinogenic potency of PANA and PBNA suggests other routes of metabolic activation besides dephenylation for both chemicals in mice.

Covalent thrombin-alpha 2-macroglobulin complexes. Evidence for bivalent cross-linking of inhibitor chains by a single enzyme molecule

Complexes formed between thrombin and alpha 2-macroglobulin (alpha 2M) were studied by polyacrylamide gel electrophoresis. The results provide evidence for the existence of a recently proposed novel enzyme-inhibitor species in which a single thrombin molecule forms two or more covalent bonds to two or more different alpha 2M chains. At least one of several slowly migrating bands (greater than 375K on nonreduced gels) that have previously been observed in the literature but not well characterized can be assigned to the new species. The involvement of the lysyl amino groups of thrombin is shown by the observation that methylation of these groups reduces the higher molecular weight bands. In addition, increasing the thrombin:alpha 2M ratio causes a relative decrease in the higher molecular weight species, suggesting that these complexes arise by intramolecular reactions that are susceptible to competition by solution thrombin. The data provide support for our previous proposal [Wang, D., Yuan, A., & Feinman, R.D. (1983) Ann. N.Y. Acad. Sci. 421, 90-97] that the 260K band seen in reduced gels is composed of two proteolyzed inhibitor subunits linked to one thrombin molecule. This intersubunit link maintains the integrity of the alpha 2M in sodium dodecyl sulfate, accounting for the high molecular weight bands under nonreducing conditions. Comparison with a synthetically cross-linked alpha 2M molecule allows a tentative but not unambiguous assignment of one of the bands to this novel structure.

Synthesis of Gp4N and Gp3N compounds by guanylyltransferase purified from yeast

Guanylyltransferase that catalyzes mRNA capping by the reaction, ppNpN + GTP----GpppNpN was purified from S. cerevisiae. The enzyme forms a nucleotidyl intermediate by phosphoamide linkage of GMP. Two guanylylated polypeptides of MR approximately 52,000 and 46,000 were obtained, the latter apparently by proteolysis of the larger component. Both forms transferred the covalently bound GMP to ppApG, yielding GpppApG. Dinucleoside tri- and tetraphosphates of the type Gp3N and Gp4N were also produced by using ribonucleoside 5'-di and triphosphates as acceptors. The purified yeast guanylyltransferase contained little or no RNA 5'-triphosphatase or methyltransferase.