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Biomedical subjects

S F Lyons

Publications and source records attributed to S F Lyons.

At least 37 records · Page 2Linked to original sources
PubMed1988

Epidemiological considerations of the present status and future growth of the acquired immunodeficiency syndrome epidemic in South Africa.

Limited epidemiological data on acquired immunodeficiency syndrome (AIDS) and human immunodeficiency virus (HIV) infection have been assembled by voluntarily reported AIDS figures, blood donor serum prevalence and high-risk sentinel population and random background population sero-prevalence studies. The HIV epidemic in South Africa can thus be shown to consist of four separate epidemics of which the heterosexual epidemic will undoubtedly constitute the major growth in this country. Intervention must be directed to shrinking the promiscuous core which sustains this epidemic by directing attention at female prostitution and limiting the reproductive rate of the epidemic by energetic and professionally directed education at an early stage of a child's school career. Sexually transmitted diseases will play a major role in the determination of the extent of the heterosexual epidemic.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Interferon status after measles virus infection.

Peripheral blood leucocytes from patients who had recently had measles infection were examined for their ability to produce alpha- or gamma-interferon, their antiviral state and the level of E enzyme. These results were compared with peripheral blood leucocytes from healthy control subjects. The results show that while peripheral blood leucocytes from control patients produced alpha- and gamma-interferon, those from the measles patients produced only alpha-interferon. The peripheral blood leucocytes from all the measles patients were in an antiviral state whereas those from only 20% of the controls were in this state. Since gamma-interferon is mainly produced by T lymphocytes, the lack of gamma-interferon production by peripheral blood leucocytes from patients with measles correlates with previously reported depressed T-cell function in patients after measles infection.

Adolescent↗
PubMed1988

Effect of interferon on Vero cells persistently infected with Sendai virus compared to Vero cells persistently infected with SSPE virus.

Persistent infections with Sendai and SSPE virus were established in Vero cells. Sequential passages of these cells were monitored by immunofluorescence and for their sensitivity to the antiviral and antiproliferative effects of interferon (IFN). The cells rapidly developed resistance to the antiviral effect of IFN as judged by the inability of IFN to inhibit the replication of exogenous Sindbis virus. This decrease was accompanied by a reduction in the induction of the 2'-5' oligo A synthetase. Both cell lines were resistant to the antiproliferative effect of IFN. A decrease or absence of IFN receptors on the surface of the cells was not found to be the cause of their resistance to IFN.

2',5'-Oligoadenylate Synthetase↗
PubMed1987

Experimental assessment of bedbugs (Cimex lectularius and Cimex hemipterus) and mosquitoes (Aedes aegypti formosus) as vectors of human immunodeficiency virus.

In vitro experiments were conducted to assess whether bedbugs (Cimex lectularius and Cimex hemipterus) and mosquitoes (Aedes aegypti formosus) could act as vectors of HIV. These insects engorged through a membrane on a blood-virus mixture. Female bedbugs were larger than males and took larger blood-meals when fed to repletion. It was determined that the full blood-meal of a female bedbug contained 0.09 x 10(5) tissue culture infectious doses (TCID) of virus and a male 0.07 x 10(5) TCID, while partial meals taken when feeding was interrupted contained 0.013 x 10(5) TCID and 0.015 x 10(5) TCID for female and male bugs, respectively. Reverse transcriptase activity was assayed after culture of insect extracts in H9 cells: this showed survival of virus in C. lectularius for up to 4 h, in C. hemipterus for up to 1, possibly 2 h, but no survival in Ae. aegypti formosus. Four attempts to transmit the virus by interrupted feeding by C. lectularius from a blood-virus mixture to uninfected blood failed. It is concluded that Ae. aegypti formosus and probably other mosquitoes are not mechanical vectors of HIV and that such transmission is also unlikely to occur in bedbugs under natural conditions.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Effect of interferon on Vero cells persistently infected with SSPE virus and lytically infected with measles virus.

The effect of lymphoblastoid interferon (IFN) on viral polypeptides synthesized in a Vero cell culture persistently infected with subacute sclerosing panencephalitis virus (SSPE-Vero) was compared to that of Vero cells infected with exogenous measles virus. After IFN treatment there was no significant decrease in the synthesis of SSPE viral proteins, but inhibition of synthesis of measles polypeptides was readily seen. In Vero and SSPE-Vero cells IFN was able to inhibit replication of Sindbis virus although the effect in Vero cells was significantly more sensitive. In both cell lines IFN was able to stimulate 2'--5' oligoadenylate synthetase (E enzyme) but not the protein kinase system. The SSPE-Vero cells showed a lower basal level of E enzyme activity than the Vero cells.

2',5'-Oligoadenylate Synthetase↗
PubMed1986

The use of interferon functional assays in the laboratory monitoring of patients with hepatocellular carcinoma receiving interferon.

Patients with hepatocellular carcinoma receiving recombinant leukocyte alpha interferon therapy were monitored using a series of assays to evaluate various components of the interferon system. Pretherapy serum interferon concentrations were not elevated significantly in these patients, although elevated levels were recorded after initiation of therapy. Both before and after interferon treatment, the peripheral blood leukocytes of the patients were shown to be capable of producing both gamma and alpha interferon when appropriately stimulated in vitro. The patients' peripheral blood leukocytes also responded to interferon therapy, with 85% resisting viral replication after treatment was initiated. However, interferon did not appear to be of therapeutic value in these patients.

Adult↗
PubMed1985

Limitations of enzyme immunoassay tests for detection of HTLV-III/LAV antibodies.

A commercial enzyme immunoassay (EIA) kit was compared with an immunofluorescence test for the detection of antibodies directed against human T-cell lymphotropic virus type III (HTLV-III). The EIA kit is recommended for the screening of blood and plasma products only and is not suitable for diagnostic purposes because of the problem of nonspecific reactions. It is also recommended that the EIA kit not be used for screening immunoglobulin preparations for anti-HTLV-III antibodies because of the problem of false-positive reactions.

Antibodies, Viral↗
PubMed1985

Sero-epidemiology of HTLV-III antibody in southern Africa.

A preliminary survey has demonstrated that antibodies directed against human T-cell leukaemia virus type III (HTLV-III), the virus implicated as the agent causing the acquired immunodeficiency syndrome, are not present in the low-risk population groups studied. The survey, in which an indirect immunofluorescence assay was used, has indicated that HTLV-III is not endemic in southern Africa (as opposed to central Africa, where it has been suggested that the virus is endemic). Anti-HTLV-III antibodies were, however, found in sera from male homosexuals, the one high-risk population group studied.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Laboratory evaluation of commercial interferon preparations.

The antiviral, antiproliferative and natural killer-cell (NKC) stimulatory activities of four commercial therapeutic interferon preparations were assayed in our laboratory. The antiviral and antiproliferative activities of each preparation were relatively similar, but an unexpectedly high NKC stimulatory activity was found in one of them. In-house determination of antiviral activity and evaluation of the antiproliferative and NKC stimulation potential of interferon preparations are essential before rational clinical trials of this agent are carried out.

Cell Division↗