Search PubMed⌕ Search

Biomedical subjects

S Cooke

Publications and source records attributed to S Cooke.

16 recordsLinked to original sources
PubMed1992

Control of gene expression in tobacco cells using a bacterial operator-repressor system.

We have investigated the efficacy of using the Escherichia coli lac operator-repressor system to control plant gene expression. The lacI gene was modified to allow optimal expression in plant cells and then placed downstream of the cauliflower mosaic virus (CaMV) 35S RNA promoter. This construct was introduced into tobacco plants by leaf disc transformation. Transgenic tobacco plants synthesized significant quantities of LacI protein (up to 0.06% of total soluble protein). We have used the E.coli beta-glucuronidase gene (gus) as the reporter gene by placing it downstream of the maize chlorophyll a/b binding protein (CAB) gene promoter. Lac operators were introduced into several positions within the CAB promoter and operator-free plasmid was used as control. Repression was assessed by comparing the transient expression from CAB-operator-gus reporter constructs in protoplasts expressing lac protein, with that in control cells not expressing the repressor. Repression varied between 10 and 90% with different operator positions. Transient assays were also performed in the presence of the inducer, isopropyl-beta-D-thiogalactoside (IPTG). In lacI protoplasts the presence of IPTG manifested itself in a 4.2-fold relief of repression. The study was extended to show regulation of expression in stable transformants. Tobacco transformants harbouring a CAB-operator-gus reporter construct and the lacI gene were shown to have repressed GUS levels, but in the presence of IPTG, repression was relieved 15-fold. We conclude that the lac repressor can enter the plant cell nucleus, find its cognate operator sequence in the chromatin to form a repressor--operator complex and effectively block transcription of a downstream gene.

Bacterial Proteins↗
PubMed1992

The antigenicity and allergenicity of microparticulated proteins: Simplesse.

New technologies are allowing the food industry to develop products from standard foods which may not be recognized in its modified form by food allergic patients. One such product, Simplesse, has been formulated by microparticulation of egg white and/or cows' milk proteins and is used as a fat substitute in many fat-laden foods. The purpose of this study was to determine whether the process of microparticulation altered the allergenicity/antigenicity of egg white and cows' milk proteins compared to the starting materials. Soluble protein fractions of Simplesse and its respective starting materials were compared to egg white, cows' milk protein, an ultra-filtered egg white/condensed milk mixture, and/or a whey concentrate by SDS-polyacrylamide gel electrophoresis. In addition, sera from 16 patients with documented egg and/or cows' milk hypersensitivity and two controls who were not allergic to egg or milk were used to assess potential allergenicity/antigenicity of these products by immunoblot (Western blot) analysis. There were heterogeneous IgE and IgG binding patterns to the food fractions among these food allergic patients suggesting differing sensitivity patterns among the individuals tested. However, utilizing both SDS-PAGE and immunoblot analyses, the major allergens in the microparticulated products were the same as those found in the starting materials, egg and cows' milk. In addition, there was no evidence of 'novel' protein fractions in the Simplesse test materials compared to the starting materials.

Allergens↗
PubMed1990

Social influences approach to smoking prevention: the effects of videotape delivery with and without same-age peer leader participation.

This study tested the hypothesis that cigarette smoking adoption among adolescents could be suppressed by providing school-based videotape instruction for resisting social influences to smoke. The utilization of same-age peer leaders was also varied to test whether their participation in the classroom would enhance program effects. Seventh grade students (N = 540) from one junior high school in Southern California were randomly assigned by classrooms (N = 15) to: (a) videotape instruction, (b) videotape instruction plus peer leader involvement, or (c) survey-only. Seventh grade students (N = 234) in a second junior high school served as a measurement-only control. Assessments were conducted at the beginning and end of the academic year. Results revealed a marked suppression in the onset of both experimental and regular smoking among those students exposed to the pressure resistance training with peer leader involvement. Pressure resistance training without peer leader involvement produced a more variable and less powerful effect on students' smoking behavior. Data collected on students' use of alcohol and marijuana revealed a generalized suppression effect, albeit weaker than for tobacco, among those students exposed to the social resistance training with peer leader involvement. Results provide further encouraging support for the use of peer-led pressure resistance training in preventing adolescent drug use.

Adolescent↗
PubMed1990

Donor rejection.

Explore the source record for details and available documents.

Humans↗
PubMed1989

Screening for cytomegalovirus antibody in a donor insemination program: difficulties in implementing The American Fertility Society guidelines.

With the recommendations of The American Fertility Society that all donors and recipients in a donor insemination programme should be screened for CMV antibody, we have documented the prevalence of CMV antibody in donors, recipients, and their partners in our clinic. Forty percent of our donors were CMV-positive, and in only 35% of the couples were both partners negative. The implications of using exclusively CMV-negative donors are examined. The necessity for further research on the detection and the transmission of various strains of CMV and the effects of cryopreservation on them is emphasized.

Antibodies, Viral↗
PubMed1989

A prospective randomized controlled trial comparing urinary luteinizing hormone dipsticks and basal body temperature charts with time donor insemination.

Especially now with the almost exclusive use of frozen semen, accurate timing of donor inseminations is an important point to address if a successful donor insemination program is to be established. To examine whether the timing of donor inseminations using urinary luteinizing hormone (LH) dipsticks (group 2) was significantly better than using basal body temperature (BBT) charts (group 1) we performed a prospective randomized controlled trial. There was no significant difference between the cumulative pregnancy rates at 6 months (0.23 versus 0.31 for groups 1 and 2, respectively) or the monthly fecundability (0.04 versus 0.07 for groups 1 and 2, respectively). Using these monthly fecundabilities we have calculated that approximately 378 patients in each arm of the trial would be needed to demonstrate a significant difference between the two groups. We therefore conclude that timing donor inseminations using urinary LH dipsticks does not significantly improve the conception rates.

Body Temperature↗
PubMed1988

A protocol for the recruitment and screening of semen donors for an artificial insemination by donor programme.

This study outlines a structured protocol for the recruitment and screening of semen donors for an artificial insemination by donor programme. One-hundred-and-ninety-one potential semen donors were assessed. A step-wise analysis of these potential semen donors is presented, reasons for and rates of rejection at each stage are documented and explained. The majority of the potential donors were rejected on the basis of unacceptable semen analysis. A simple, structured approach to the assessment of potential semen donors is proposed.

Humans↗
PubMed1986

Radioiodine treatment of solitary functioning thyroid nodules.

Forty-eight patients with hyperthyroidism due to a single toxic nodule have been treated with radioiodine (131I). The mean follow-up period is 37 months. All patients were rendered euthyroid and no cases of hyperthyroidism have been observed. Forty patients required only one dose of 131I to render them euthyroid, six patients required more than one dose and two patients initially rendered euthyroid relapsed during follow-up and required further 131I treatment. It is concluded that a single fixed dose of 131I is a simple, effective treatment for a solitary toxic thyroid nodule and does not cause hypothyroidism.

Adult↗
PubMed1985

Endomyocardial complications of the Churg-Strauss syndrome.

Although many similarities exist between the Churg-Strauss syndrome and the hypereosinophilic syndrome, these two disorders have hitherto been characterized by different types of cardiac disease. Two cases of the Churg-Strauss syndrome are described where the typical endomyocardial lesion of the hypereosinophilic syndrome dominated the clinical picture.

Adult↗
PubMed1978

Imaging the bowel with technetium--an aid in gallium studies.

Three cases are present to demonstrate the usefulness of oral or rectal technetium-99m preparations in locating the stomach and bowel in relation to abnormal accumulation of gallium-67 within the abdomen. In this way, the concentration of gallium in an abscess or a tumor may be distinguished from its physiologic excretion into the bowel.

Abdomen↗