Scale and corrosion control with combined dolomite/calcite filter.

Water quality is a major operational issue for boiler operation and control. If the water is hard scale control is required and if it is soft then corrosion control is an issue. Here a two stream boiler test rig has been used to test the effect a fixed bed filter has on the scaling and corrosion properties of both hard and soft waters. The filter effectively controlled the pH, hardness and alkalinity of both waters leading to significant decreases in scale formation and effective control of corrosion.

Concomitant infection of HTLV-I and HIV-1: prevalence of IgG and IgM antibodies in Washington, D.C. area.

Serum samples collected from four groups of individuals in the Washington, D.C. area were examined for the presence of IgG and IgM classes of antibody reacting against HTLV-I and HIV-1. These four groups were: (1) healthy adults with negative premarital VDRL test for syphilis (n = 113), (2) miscellaneous common disease patients (n = 155), (3) drug abusers (n = 130), and (4) homosexual men (n = 187). The former two groups are considered to be low-risk groups, and the latter two, high-risk groups. The prevalence of IgG antibody on ELISA/Western blot tests for these groups were respectively: (1) 5.3%/1.8%, (2) 5.2%/1.9%, (3) 13.9%/4.6%, and (4) 4.3%/1.6% for HTLV-I, and (1) 2.7%/0.9%, (2) 4.5%/0%, (3) 12.3%/5.4%, and (4) 8.0%/5.9% for HIV-1. Instances of possible concomitant infection as shown by the presence of antibodies against both HTLV-I and HIV-1 were found only in the latter two high-risk groups, i.e. two (1.5%) in group (3), and three (1.6%) in group (4) as confirmed by both Western blot and immunofluorescence tests. Out of 97 sera collected from drug abusers in 1985-86 which had IgG antibody by Western blot test against HIV-1, 23 (23.7%) were HTLV-I antibody positive by ELISA test (Group 5), and 8 of these were confirmed by Western blot test. Among these 8 persons, IgM antibody against HTLV-I was found in 2, while that against HIV-1 was positive in 7 persons.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of xenotropic and dual-tropic type C retroviruses isolated from Abelson tumour.

Tumours induced in Balb/c mice by Abelson virus complex were found to contain a xenotropic virus (A-X-MuLV) and an NB-tropic, dual-tropic virus (NBX), in addition to the Moloney leukaemia virus (M-MuLV) and the defective, transforming Abelson virus genome. Both A-X-MuLV and NBX virus were presumably present in a genomically masked form and could be recovered only by co-cultivation of tumour cells with permissive cells. Only about 0.87% and 0.13% of the viruses in the co-culture supernatant represented A-X-MuLV and NBX virus respectively; the majority were M-MuLV. The NBX virus acted more efficiently than the HIX virus (Fischinger et al., 1975) as helper to rescue murine sarcoma virus (MSV) from S+L-cells of hamster, rat and mouse origin, whereas the converse was true for those of cat and human origin. The interference and nuetralization patterns suggested that the NBX virus was an env gene recombinant between A-X-MuLV and M-MuLV. The fact that NBX virus cross-reacted in radioimmunoassays with gp70s of both M-MuLV and Balb: virus-2 provides evidence for the recombinant nature of the NBX gp 70-coding gene which was probably derived from both M-MuLV and a virus similar to Balb: virus-2 or A-X-MuLV. The presence of a unique antigenic determinant on the gp70 of NBX virus is also suggested. Both A-X-MuLV and NBX virus cross-reacted with type-specific p12s of M-MuLV and Balb: virus 2- suggesting that the gag gene coding for p12 of NBX virus was derived from the A-X-MuLV, which was itself a recombinant, its p12-coding gene being derived from both Balb: virus-2-like virus and M-MuLV. The NBX virus was not oncogenic when tested in newborn Balb/c mice.

Carcinomas induced by cell lines cultivated from normal mouse placentas.

Cell lines have been established from placentas of various strains of mice by in vitro cultivation. The established lines appear to be trophoblast cells as judged from their production of gonadotropin-like substance and their production of gonadotropin-like substance and steroid hormones. The cell lines lack detectable H-2 antigen, Fc receptor sites, Thy 1 and antigen and surface immunoglobulin determinants. In addition, the cells are resistant to murine type-C RNA tumor virus infection. The resistance is due to a block of viral replication after the stages of viral adsorption and penetration. The cell lines induced carcinomas after injection into adult mice of original host strains. Usually at least 2 x 10(6) cells are required to induce tumors by i.p. or s.c. injection. Transplantation of the tumor cells to various strains of mice revealed that some strains accepted and some strains rejected the transplant. Genetic crossings between susceptible and resistant mouse strains indicate that susceptibility to transplantation of tumor is determined by a single pair of dominant autosomal genes.

Natural killer cell activity associated with reticulum cell neoplasms.

A marked increase in natural killer (NK) activity is observed with lymphoid cells prepared from SJL/J mouse spleen and lymph nodes, in which a transplantable reticulum-cell neoplasm (RCN) is growing. The killer cells are non-adherent, non-phagocytic, relatively resistant to X-ray, and scarcely or only partially inactivated by treatment with anti-Thy 1.2 serum and complement. The killer activity is directed against a wide variety of tumor target cells, not requiring homology in histocompatibility, but is selective and not indiscriminate. Kinetics of in vivo development on NK activity, competitive inhibition of in vitro cytotoxicity by target cells and their membrane extracts are described. The NK activity appears to increase in parallel with the infiltration and growth of RCN in these organs. No such augmented NK activity was observed with other types of tumors that grew in these organs of SJL/J mice. (C57BL/6 X SJL/J)F1 mice pretreated with silica to abrogate Hh restriction and subsequently injected with RCN of SJL/J (H-2s) origin supported the growth of transplanted RCN. The high NK activity associated with this RCN was markedly reduced by in vitro treatment with anti-H2b serum plus complement, indicating the host origin of NK cells. However, the close association of RCN growth with elevated NK activity may indicate a special function of RCN in promoting NK activity by an unknown mechanism(s) of cellular interactions.

Enzyme immunoassay for feline oncornavirus-associated cell membrane antigen (FOCMA) and detection of FOCMA in cell extract by enzyme immunoassay inhibition test.

An enzyme immunoassay (EIA) for FOCMA has been developed. The assay uses alkaline phosphatase-conjugated rabbit anti-cat IgG as the second antibody and p-nitrophenyl phosphate as the substrate for the enzyme to detect cat FOCMA antibody bound to the target cells. In comparison with the indirect immunofluorescence (IIF) test, which was originally used for FOCMA assay, our results showed a good correlation between the two methods. The EIA gives a more objective measure of FOCMA reactivity than does IIF. FOCMA was successfully extracted from FOCMA-positive cell membranes by 0.5% Triton X-100 and further fractionated by ammonium sulfate. The FOCMA activity was assayed by IIF and EIA inhibition test. Most of the FOCMA activity was found in the fractions precipitated by 30% and 50% ammonium sulfate saturation.

Experimental horizontal transmission of feline leukemia viruses of subgroups A, B, and C.

Experiments were conducted with cats in metal cages inside plastic isolators to determine whether feline leukemia virus (FeLV) of the three known antigenic subgroups (A, B, and C) is transmitted horizontally from infected cats to normal "contact" cats. Blood smears collected at weekly intervals were examined by the fixed-cell, indirect immunofluorescence test for FeLV internal p30 to follow the spread of infection from inoculated cat to contact cats. These studies established that viruses of all three subgroups are transmitted horizontally among kittens and adults with slightly varying degrees of speed. Virus was reisolated from one horizontally infected contact cat of each group, and its envelope antigenic type was the same as that originally inoculated into one cat of the same group. After the cats acquired the infection, they became chronic carriers of virus (viremic) during the observation period of 9 or 11 weeks post inoculation.

Viral interference in feline leukemia-sarcoma complex.

Feline leukemia viruses replicate in feline embryo fibroblast cultures without causing visible effects. The virus-infected cultures acquire a resistance to superinfection with the closely related focus-forming feline leukemia pseudotypes of murine sarcoma virus and the feline sarcoma viruses. This induction of viral interference in tissue cultures with the cell-transforming effects of the challenge viruses can be used as a quantitative in vitro assay for the detection of feline leukemia viruses. Preliminary observations indicate that the interference is virus strain-specific (type-specific) and suggest the existence of distinct differences in viral envelope characteristics demonstrable in the viral interference tests.

Trans-species rescue of defective genomes of murine sarcoma virus from hamster tumor cells with helper feline leukemia virus.

This report describes a trans-species rescue of defective MSV genome with helper leukemia virus derived from cats. This rescue was achieved by in vitro co-cultivation of hamster tumor cells with feline embryo cells in the presence of helper feline leukemia virus (FeLV), or by inoculation of tumor cells into FeLV-infected newborn cats. The rescued focus-forming viruses produced foci in feline embryo cultures but not in cultures of mouse, rat, and hamster species. One isolate was tested and found to induce sarcoma in a kitten. Antigenic and viral interference studies indicated that the focus-forming virus has the viral envelope of FeLV. Virus stocks consisted of a mixture of focus-forming particles and a 1000-fold excess of helper FeLV. Virus assay pattern in feline embryo cultures with or without added helper FeLV indicated that this helper virus is required for the transformation of feline cells.