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Biomedical subjects

S Halbert

Publications and source records attributed to S Halbert.

7 recordsLinked to original sources
PubMed2000

Progress on strain differentiation of Citrus tristeza virus and its application to the epidemiology of citrus tristeza disease.

Citrus tristeza virus (CTV) occurs in most citrus producing regions of the world, and it is the most serious viral pathogen of citrus. With the recent establishment of the brown citrus aphid, Toxoptera citricida, its most efficient vector, on Madeira Island (Portugal) and in Florida (USA) and the countries of the Caribbean Basin, the impact of CTV is likely to increase in these regions. Since there are many strains of CTV and CTV infections frequently occur as mixtures of several strains, it is necessary to be able to distinguish the strains for regulatory purposes, disease management and epidemiology. We describe the evolution of techniques developed to detect CTV and to differentiate the individual strains, and present the results of tests using these latest methods on CTV isolates from mainland Portugal, Madeira Island and Florida. Mild and decline-inducing strains of CTV were detected in mainland Portugal and mild, decline-inducing and severe stem pitting strains on Madeira Island. In Florida we demonstrated the presence of infections that reacted with probes made against stem pitting strains not previously detected there. It is concluded that CTV presents a significant threat to citrus production in mainland Portugal, on Madeira Island and in the neighbouring countries of the Mediterranean Basin, as well as in Florida, elsewhere in the USA and throughout the Caribbean Basin, especially following the widespread establishment of T. citricida throughout the region.

Amino Acid Sequence↗
PubMed1986

Herpes zoster: a possible early clinical sign for development of acquired immunodeficiency syndrome in high-risk individuals.

Zoster is uncommon before the age of 50 years in immunologically normal individuals, but it occurs with increased frequency in people who are immunosuppressed. A retrospective review of 300 patients with acquired immunodeficiency syndrome associated with Kaposi's sarcoma, revealed that 8% had prior zoster, a rate that is sevenfold greater than historic controls of the same age. We prospectively examined forty-eight patients, with no known immunodeficiency or signs of AIDS or AIDS related complex (ARC), who presented with zoster localized to the thoracic region. Forty-one patients had known risk factors for AIDS and thirty-five had antibody to the AIDS-associated virus (AAV) at the time of presentation. One seropositive subject had no known risk factors. Absolute lymphocyte counts, lymphocyte OKT4/OKT8 ratios, and lymphocyte mitogen responses were all depressed in subjects with antibody to AAV when compared with seronegative individuals. Seven of thirty-three AAV antibody-positive subjects, who could be followed longitudinally, developed AIDS from 1 to 28 months (mean = 13) after zoster. One antibody-negative subject seroconverted to become AAV seropositive 16 months after zoster and developed Kaposi's sarcoma 1 month later. These eight subjects had persistently low lymphocyte OKT4/OKT8 ratios and elevated beta-2 microglobulin. In patients at risk for AIDS, the occurrence of zoster may be one sign that heralds the marked depression of cellular immunity associated with AIDS or ARC.

Acquired Immunodeficiency Syndrome↗
PubMed1986

The clinical application of an ELISA technique for the detection of antihistone antibodies.

A rapid reproducible technique for measuring antihistone antibodies is described in which unfractioned nuclear histones covalently bonded to plastic discs are employed in an ELISA system. All 20 patients with drug induced lupus erythematosus had antihistone antibodies, usually at high titer. In contrast, 22% of 18 asymptomatic patients with drug induced antinuclear antibodies (ANA), 15% of 20 patients with seropositive RA and 42% of 60 patients with systemic lupus erythematosus (SLE) had detectable antihistone antibodies. High titers of antihistone antibodies were not seen in drug induced ANA or RA. This assay differentiates between patients with drug induced lupus and drug induced ANA (p less than 0.01) and drug induced lupus erythematosus and SLE (p less than 0.01). In patients with SLE antihistone antibodies had no association with disease activity.

Antibodies, Antinuclear↗
PubMed1984

The functional potential of the rabbit fimbria.

The ability of the normal rabbit fimbria to retrieve eggs after progressive reduction of its mucosal surface was tested on 16 New Zealand white rabbits. Group 1 had a small fimbrial resection; group 2 had a large one. The resected tissue was weighed, and in both groups the contralateral fimbria (internal control) was cut and sutured without resection. Four weeks later the animals were mated, and 12 hours afterwards the ovulation sites on each ovary were counted and both tubes excised. In vivo observations of the transport of cumulus surrogates by the experimental fimbria were made before tubal excision in group 2 animals. The natural eggs retrieved by the fimbria were recovered by flushing the resected tubes with saline. The infundibulum and fimbria were cut from the ampulla and weighed to calculate the amount of fimbrial resection achieved. In group 1 the experimental side retrieved 82% of the eggs; in group 2 the experimental side retrieved 72%. In vivo observations revealed the presence of a spontaneously formed neofimbria that transported cumulus surrogates in a normal pattern and at a normal rate. The fimbria appeared dispensable, a fimbrialike structure formed spontaneously, the functional results were optimal, and the number of ovulation after surgery was unchanged. Some similarities can be observed in women.

Animals↗
PubMed1978

A direct enzyme-linked immunosorbent assay (ELISA) for detection of antibodies for rubella virus in human sera.

A direct enzyme-linked immunoassay (ELISA), based on the "sandwich" principle on an antigen-coated plastic disc, was used for the rapid detection of rubella antibody. Results were obtained the same day, and the prior adsorption of sera to remove non-specific inhibitors was not necessary. The ELISA was compared to the hemagglutination-inhibition (HAI) test on 500 serum samples. There was general agreement between the two methods; most discrepancies occurred with low-titered HAI positive sera. There was excellent correlation between the tests with serum samples negative for rubella antibodies and those samples with HAI titers greater than or equal to 1:40.

Animals↗
PubMed1975

Methods for studying oviductal physiology.

In studying oviductal physiology, it is important to sort out the complex interrelationships between muscle, cilia, nerves and secretory processes as they each of themselves, or in concert, effect gamete transport. In this review, a variety of physiological techniques and bioengineering approaches which have been used to monitor contractile and ciliary activity, are described and critically evaluated.

Animals↗