Effects of cobra venom factor treatment on latent feline leukemia virus infection.

The role of the complement system in containment of feline leukemia virus infection was studied by cobra venom factor treatment of feline leukemia virus-immune cats. One to three weeks after cobra venom factor treatment, an increase in viral antigen in marrow myelomonocytic cells and circulating immune complexes was noted. Prevention of reactivation of feline leukemia virus infection may in part depend on an intact complement system.     

Mechanisms of serotonin-induced lymphocyte proliferation inhibition

When human peripheral blood lymphocytes were stimulated with phytohemagglutinin in the presence of serotonin, inhibition of [3H]thymidine incorporation occurred, the most marked inhibition occurring at high (10(-3)M) serotonin concentrations. This effect could not be reversed by the addition of Interleukin 2 (IL-2)-containing supernatants. Cytofluorometric analysis showed that virtually all of the cells remained in the G0 phase (unactivated) at 24 hr while some of the cells entered the G1a and G1b phases of the cell cycle by 42 hr. The cellular production of IL-2 was not affected by serotonin, as supernatants of treated cultures contained essentially the same IL-2 titers as did control cultures. Serotonin seemed to primarily affect cell activation and had little or no effect on proliferating cells. This was further confirmed by the lack of effects of serotonin on a variety of established proliferating lymphocyte, macrophage, and fibroblast cell lines. By contrast, dose-dependent inhibition of IL-2-dependent CTLL cells occurred. Serotonin was not toxic even at 10(-3) M concentrations. A marked decrease in IL-2 receptors and a change in their distribution on responder cells was seen when treated cultures were examined with the anti-Tac monoclonal antibody. At 24 hr this effect was contrastingly not seen for the OKT-8 marker, although a slight decrease in OKT-4-positive cells was seen. Serotonin thus produced an inhibition of lectin-stimulated lymphocyte proliferation via a mechanism independent of IL-2 production, and caused a decrease in the expression and distribution of IL-2 receptors on the surface of responder cells.     

Primary structure of human alpha 2-macroglobulin. I. Isolation of the 26 CNBr fragments, amino acid sequence of 13 small CNBr fragments, amino acid sequence of methionine-containing peptides, and alignment of all CNBr fragments

The isolation of the 26 CNBr fragments from the identical Mr = 180,000 subunits of human alpha 2-macroglobulin is described. The fragments have been purified by combinations of gel chromatography, ion-exchange chromatography, high voltage paper electrophoresis, paper chromatography, and high performance liquid chromatography. The complete amino acid sequences of 13 small CNBr fragments have been determined. These fragments include CB1 (residues 1-9), CB3 (residues 79-98), CB4 (residues 99-128), CB9 (residues 442-477), CB10 (residues 478-497), CB13 (residues 644-650), CB14 (residues 651-665), CB15 (residues 666-674), CB16 (residues 675-690), CB19 (residues 937-945), CB20 (residues 946-954), CB24 (residues 1356-1362), and CB25 (residues 1363-1375). The fragments determined account for 200 of the 1451 residues of the subunits of alpha 2-macroglobulin. Most likely, Cys-6 of CB9 is bound to the corresponding residue in CB9 from another subunit, thus forming an interchain disulfide bridge in alpha 2-macroglobulin. Cys-1 of CB15 is bound to Cys-35 of CB12. CB15 contains a pair of Gln residues that can react covalently with amines in a factor XIIIa-catalyzed process (Gln-5 and Gln-6). CB16 contains the primary cleavage sites for proteinases in the bait region of alpha 2-macroglobulin (-Arg7-Val-Gly-Phe-Tyr-Glu-). CB20 contains the residues which in native alpha 2-macroglobulin presumably form an internal reactive beta-cysteinyl-gamma-glutamyl thiol ester (Cys-4 and Glx-7). Partial NH2- and COOH-terminal sequence data are given for the 13 large CNBr fragments. Complete or partial sequence determination of 19 methionine-containing peptides or variants thereof allow the alignment of all the CNBr fragments.     

Antagonism of xylazine hydrochloride with yohimbine hydrochloride and 4-aminopyridine in captive wapiti

Eight captive wapiti (Cervus elaphus nelsoni) were injected with xylazine hydrochloride on two occasions during March and April 1984. Animals were grouped into a modified Latin square design and were given either successive injections of yohimbine hydrochloride and 4-aminopyridine (4-AP) to antagonize the sedative effects of xylazine hydrochloride or permitted an unantagonized recovery. Induction times ranged from 3 to 26 min with excited and wild animals requiring a supplementary dose. Time until walking was significantly (P less than 0.005) shorter in the group given successive injections (given i.v.) of the reversal drugs yohimbine hydrochloride (0.15 mg/kg) and 4-AP (0.30 mg/kg) than those animals during unantagonized recoveries. Marked increase in heart rate and respiratory rate were observed in animals within 3 min after successive injections of yohimbine hydrochloride and 4-AP. There was no occurrence of convulsions and animals did not relapse to profound sedation. Slight muscle tremors were observed in one animal which received a dose of 0.35 mg/kg of 4-AP. This drug combination can reduce markedly the duration of recovery from xylazine hydrochloride-induced sedation in wapiti.     

Two proteolytic degradation products of calf-thymus poly(ADP-ribose) polymerase are efficient ADP-ribose acceptors. Implications for polymerase architecture and the automodification of the polymerase

Two polypeptides with molecular masses of 76 and 59 kDa were found to copurify with poly(ADP-ribose) polymerase from calf thymus, and to be as efficient acceptors of ADP-ribose as the polymerase itself. Analysis of their CNBr fragments by sodium dodecylsulfate/polyacrylamide gel electrophoresis revealed that the polypeptides were derived from the 112-kDa polymerase. Isolation of poly(ADP-ribose) polymerase in the absence of protease inhibitors resulted in a loss of more than 90% of the polymerase activity and an increased proportion of the 76-kDa and 59-kDa polypeptides in the final polymerase preparation. When the polymerase and the two polypeptides were separated by gel filtration or polyacrylamide gel electrophoresis in 5% acetic acid, no polymerase activity was found associated with the two fragments. Analysis of the CNBr fragments of the three polypeptides after incubation of the enzyme preparation with [32P]NAD showed that most of the fragments were radioactive, indicating multiple ADP-ribosylation sites. Several ADP-ribosylated fragments were found to be common to all three polypeptides, or to two of them.     

Significance of the delta 5 and delta 4 steroidogenic pathways in the hamster preovulatory follicle

Isolated hamster granulosa cells and theca from preovulatory follicles were incubated in vitro for 2 and 6 h in the absence/or presence of LH and steroid substrates. The purpose of the experiments was to determine, in theca, the relative activities of the delta 5 and delta 4 pathways under controlled conditions, and to compare the ability of granulosa cells and theca to form progesterone from exogenous pregnenolone. The results of the experiments show that the delta 5 pathway in theca predominates before and up to 2 h after LH stimulation. The delayed effect of LH after 2 h is a switch from delta 5 to delta 4 as the major metabolic pathway. Progesterone formation from exogenous pregnenolone is 7 to 10 times greater in unstimulated granulosa cells than in theca. Acute effects of LH lead to increased conversion of exogenous pregnenolone to progesterone in granulosa cells but not theca. LH does, however, acutely stimulate the thecal conversion of DHEA to androstenedione. The longer term effect of LH in both cell types is to increase pregnenolone conversion to progesterone.     

Sacramento's Day-Treatment Center for Autistic Children

A report of two years'' operation of a day-treatment center for autistic children is given. A brief historical review and a capsule summary regarding current concepts on autism are presented. The educational and treatment programs at the center are described, and two case vignettes illustrate the progress of the children. Highlights from group counseling sessions with the mothers of autistic children reveal the conflicts with which parents of disturbed children must deal. The two-year experience indicates that the identification of autism at an early age is crucial and that a day-treatment facility has much to offer the psychotic child and his parents.     

Acquisition of a lysosomal enzyme by myoblasts in tissue culture

Skeletal muscle myoblasts from different sources acquired high levels of the lysosomal enzyme beta-glucuronidase, when they were cultured together with mitogen-activated lymphocytes. Immunofluorescent staining, thermal stability, and electrophoretic mobility showed that the increase in enzyme activity in the myoblasts was due to the presence of the lymphocyte form of the enzyme. Although myoblasts were able to take up exogenous beta-glucuronidase from the culture medium by mannose 6-phosphate receptor-mediated endocytosis, enzyme acquisition during co-culture with lymphocytes was independent of this pathway. Enzyme transfer from the lymphocytes was found to require direct cell-cell contact with the muscle cells, and was accompanied by an increase in beta-glucuronidase activity in the lymphocytes themselves. Since this additional activity was also due to the presence of the lymphocyte form of the enzyme, these results indicate that interaction with the muscle cells induced the de novo synthesis of beta-glucuronidase in the lymphocytes.     

Differentiation between Actinobacillus (Haemophilus) actinomycetemcomitans, Haemophilus aphrophilus and Haemophilus paraphrophilus by multilocus enzyme electrophoresis

Genetic relationships among isolates assigned to Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus and H. paraphrophilus were determined by analysis of electrophoretically demonstrable allelic variation in 14 structural genes encoding metabolic enzymes. Among the 51 isolates analysed there were 25 electrophoretic types (ETs), among which mean genetic diversity per locus was 0.753. Cluster analysis of ETs demonstrated one well-defined group of 11 ETs representing solely the genotypes of all 17 isolates assigned to A. actinomycetemcomitans. The remaining 14 ETs represented the genotypes of the 34 isolates of H. aphrophilus and H. paraphrophilus. With the exception of ATCC 13252, all strains of H. aphrophilus were closely related, whereas strains assigned to H. paraphrophilus included distantly related lineages, some of which were similar to those of H. aphrophilus and should be assigned to this species. Thus, the study showed that there is no significant overall genetic similarity between A. actinomycetemcomitans and the two Haemophilus spp.     

Type XII collagen. A large multidomain molecule with partial homology to type IX collagen

Three overlapping cDNAs encoding alpha 1 (XII) collagen have been isolated and sequenced. The DNAs define five sequence domains within the chain. Three domains are nontriple-helical; two are relatively short triple-helical regions. The amino acid sequences of tryptic peptides derived from 16- and 10-kDa pepsin-resistant fragments isolated from tendon extracts are in full agreement with the deduced sequences of the triple-helical regions. Two of the five sequence domains in alpha 1 (XII), one triple-helical and one nontriple-helical, show a high degree of similarity to regions in type IX collagen chains. In addition, examination of seven exons in the alpha 1 (XII) gene shows that the gene is, in part, similar to the structure of type IX collagen genes. Therefore, collagen types IX and XII are partially homologous. The alpha 1 (XII) sequence data predict an asymmetric structure for type XII collagen molecules, fully consistent with the rotary shadowing images. These images show a triple-helical 75-nm tail attached through a central globule to three finger-like structures, each 60 nm long (Dublet, B., Oh, S., Sugrue, S. P., Gordon, M. K., Gerecke, D. R., Olsen, B. R., and van der Rest, M. (1989) J. Biol. Chem. 264, 13150-13156).