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Biomedical subjects

G Osman

Publications and source records attributed to G Osman.

9 recordsLinked to original sources
PubMed2003

Wolbachia infection and the expression of cytoplasmic incompatibility in sandflies (Diptera: Psychodidae) from Egypt.

A PCR-based method was used to screen four laboratory colonies of sandflies for Wolbachia infection. The colonies - one of Phlebotomus langeroni, one of P. bergeroti and two of P. papatasi - were all derived from sandflies collected in Egypt. Only one of the colonies, derived from P. papatasi collected in Sinai, was found infected. The sequence of the PCR product for this colony was identical to that previously reported for the Wolbachia in P. papatasi from Israel. The induction with tetracycline of cytoplasmic incompatibility (CI) in flies from the P. papatasi (Sinai) colony was then investigated, through reciprocal crosses between treated and untreated P. papatasi siblings. Partial CI expression was attained in the crosses involving antibiotic-treated (i.e. uninfected) females, whether the males used were infected with Wolbachia or had also been cleared of Wolbachia by antibiotic treatment. Most (75%) of the eggs oviposited by uninfected females that had been crossed with infected males, and most (58%) of those laid by uninfected females that had been crossed with uninfected males, failed to hatch. These results provide the first published evidence showing that Wolbachia infection in sandflies is advantageous to the insects. The failure to detect Wolbachia in one of the colonies derived from Egyptian P. papatasi or in the colonies derived from Egyptian P. bergeroti and P. langeroni may indicate that the inter- and intra-specific spread of Wolbachia is discontinuous, even within one country.

Animals↗
PubMed1999

Predictive parameters of joint disease in DBA/1 transgenic mice.

We recently reported an accelerated onset of collagen-induced arthritis in DBAII mice overexpressing a T cell receptor Valpha11.1/Vbeta8.2 transgene as a preclinical animal model for age-associated T cell dysfunction. The accelerated onset is due to a transgenically sensitized T cell population that reacts to bovine type 11 collagen without prior in vivo sensitization. The model presents a readily observable distal joint phenotype that would allow preliminary aging and intervention studies to be evaluated by monitoring the presence or absence or degree of phenotypic expression of disease. In order to characterize clinical signs, we evaluated 69 transgenic mice in six different experiments for anticollagen antibody levels, and assigned each a modified arthritic score based on the degree of redness or swelling of the digital joints. We also correlated these parameters with signs of distress, including weight bearing, activity levels, and body posture. The average onset of disease was consistently within a 28 to 35-day period. The average arthritic score at the time of onset was 8. We found that none of the parameters predicted the onset of joint disease, but the modified scoring system reflected the severity of joint disease and predicted the degree of distress associated with the acute inflammation. The ability to determine the severity of joint disease by gross physical examination is a useful clinical feature because a numerical score is reflective of the degree of inflammation. Because the transgenic mouse model is a T cell-driven disease, the effect of aging on T cell activity can be monitored easily. In addition, the use of our modified arthritic scoring system makes it possible to conduct mouse experiments in a humane manner.

Aging↗
PubMed1990

Prevention and treatment of murine experimental allergic encephalomyelitis with T cell receptor V beta-specific antibodies.

Experimental allergic encephalomyelitis (EAE) is a model system for T cell-mediated autoimmune disease. Symptoms of EAE are similar to those of multiple sclerosis (MS) in humans. EAE is induced in susceptible animal strains by immunization with myelin basic protein (MBP) and potent adjuvant. The major T cell response to MBP in B10.PL mice is directed towards an NH2-terminal epitope and involves T cells expressing either V beta 8.2 or V beta 13 gene segments. Animals treated with a TCR V beta 8-specific mAb have a reduced incidence of EAE. We report here that the in vivo administration of a combination of anti-V beta 8.2 and anti-V beta 13 mAbs results in a long-term elimination of T cells involved in the response to MBP. When given before MBP immunization, anti-TCR antibody treatment leads to nearly complete protection against EAE. Antibody treatment also results in a dramatic reversal of paralysis in diseased animals. Thus, treatment with a combination of V beta-specific antibodies is a very effective therapy for the prevention and treatment of EAE. It is hoped that the future characterization of TCR V gene usage in human autoimmune diseases may lead to similar strategies of immune intervention.

Animals↗
PubMed1986

Radiation-associated thyrotoxicosis.

We studied 154 consecutive patients with a diagnosis of thyrotoxicosis seen at Roswell Park Memorial Institute from 1963 to 1982. The retrospective review of the clinical materials revealed that 23 (15%) had a previous history of therapeutic radiation for various diseases. The radiation dose ranged from several to 3600 rads to the thyroid with a mean latency of 14.2 +/- 3.0 years. In 11 out of 16 patients who were tested for antithyroglobulin and antimicrosomal showed positive titers of either or both antibodies (69%). In a small number of patients, thyroid stimulating immunoglobulins were studied; long-acting thyroid stimulators (LATS) were positive in one of six tested and thyrotrophin binding inhibitory immunoglobulins (TBII) in five of eight. The radiation-associated thyroidal dysfunction appears to be associated with the organ-specific autoimmune processes and could manifest as either hypo- or hyperfunction of the gland.

Acne Vulgaris↗
PubMed1985

Radiation associated hyperthyroidism in patients with gynecological malignancies.

To determine the effect of abdominal and/or pelvic irradiation for gynecological malignancies on the later development of hyperthyroidism, 1,884 medical records of the patients diagnoses as carcinomas of cervix and corpus uteri, and of ovary were reviewed. Among 1,269 patients with radiation therapy, 5 patients developed hyperthyroidism after irradiation to the abdomen and/or pelvis. This is a statistically significant increase when compared with an epidemiological study. Radiation dose to the thyroid was estimated to be 30 to 200 rads. Two other patients who were irradiated to the nose or supraclavicular region in addition to the abdomen also developed hyperthyroidism. However, none of 581 patients without radiation therapy became hyperthyroid. The results indicate that radiation therapy for treatment of gynecological malignancy gives a significant radiation exposure with an increase in the incidence of subsequent hyperthyroidism.

Adolescent↗
PubMed1977

Influence of collimating design on central axis depth dose of 10-40 MeV electron beams.

Electron beam measurements were performed in this investigation on three different collimating arrangements in order to study their effect on central axis depth doses. The relative central axis doses for 10, 20 and 34 MeV as a function of area from 10 to 200 cm2 for rectangular, square and circular field sizes were studied at 2.6 and 4.8 gm/cm2 depths in a lucite phantom. Results are presented and are discussed in terms of electron contamination produced by the internal structure of the collimator used.

Electrons↗
PubMed1976

Dose distribution of therapeutic electron beams and automation of treatment planning.

Until the present time, there has been no mathematical evaluation of the therapeutic electron beams in tissue material. Electron treatments are becoming universally applied from betatrons and linear accelerators. There is, therefore, a need for dosimetric programming of hospital computers for electron treatment planning such as those used in photon beam dosimetry. In this study, we have developed a theoretical model for dose calculation in a clinical therapeutic electron beam (Osman, 1972 and 1973). On the basis of this proposed theory, one can predict dose profiles at any source to skin distance "SSD"' and at any depth in tissue "X". Our theoretical model is based on considering the clinical broad electron beam used in radiation therapy as being made up of an infinite number of identical and initially parallel pencil beam components, each of minute width, to which the existing theories (Lewis, 1950; Attix et al., 1968) on electron multiple scattering, in the concerned medium apply. Dose profiles in tissue, as obtained from this model, could provide useful information as input data for routine programs of treatment planning with high energy electron beams, using mini-computers. Further, it is also possible to account for any body inhomogeneity such as subcutaneous fat, lung, air volumes, body cavities, fluids and bone from the basic parameters of these media.

Automation↗