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Biomedical subjects

S L Day

Publications and source records attributed to S L Day.

12 recordsLinked to original sources
PubMed2001

Defective lentiviral vectors are efficiently trafficked by HIV-1 and inhibit its replication.

Gene therapy against HIV infection should involve vector-mediated delivery of anti-HIV therapeutic genes into T-lymphocytes and macrophages or, alternatively, hematopoietic progenitors. Transduction of mature cells with defective vectors would have limited success because the vector would disappear with cell turnover. However, if a vector could be trafficked by wild-type HIV, initial transduction of a majority of the population would not be required, as the vector would be able to spread. We describe HIV-1-based lentiviral vectors that are efficiently packaged and trafficked by HIV-1, allowing a small number of cells initially transduced to spread the vector within a nontransduced cell population. We examined whether the presence or absence of the rev gene and the Rev-responsive element (RRE) would have a noticeable effect on the ability of lentiviral vectors to be trafficked and to inhibit HIV-1 replication. We found that replacement of rev/RRE with a constitutive transport element from Mason-Pfizer monkey virus had no apparent effect on trafficking and did not change the intrinsic inhibitory abilities of the vectors. We also constructed a rev/RRE-independent HIV-1-derived vector carrying a trans-dominant negative mutant of HIV-1 Rev, RevM10. This vector was less efficiently trafficked by HIV-1 and, despite the presence of an anti-HIV-1 gene, RevM10, was less efficient at inhibiting HIV-1 replication when introduced into a target T-cell population.

Cells, Cultured↗
PubMed2001

Multigene lentiviral vectors based on differential splicing and translational control.

Lentiviral vectors, so far, have been optimized for the expression of a single open reading frame. Certain practical applications of gene therapy will, however, require expression of multiple genes. The goal of this study was to explore the feasibility of directing expression of two marker genes from a lentiviral vector. We designed two types of multigene lentiviral vectors. First, we used a strategy based on the natural splicing signals of HIV-1, by which multiple mRNAs are generated from a single transcriptional unit. A second strategy was construction of a polycistronic mRNA using a translational cis-acting element, the encephalomyocarditis virus internal ribosome entry site (IRES). Our studies show that the inclusion of multiple genes in lentiviral vectors does not result in reduction in virus titers or in the loss of ability to infect nondividing cells. We introduced mutations in tat and/or rev to test whether splicing modulates the relative levels of expression of reporter genes. We also developed a truncated version of tat, which is devoid of the apoptosis-associated domain. Inclusion of this tat mutant in a lentiviral vector resulted in the generation of virus with titers similar to those of lentivirus vectors expressing wild-type tat.

Alternative Splicing↗
PubMed1996

Assistive technology for postsecondary students with learning disabilities.

An increasing number of students with learning disabilities are attending postsecondary institutions. To meet the educational demands of these students, support service providers will likely rely on assistive technology. This article lists types of assistive technology appropriate for use with persons with learning disabilities at the postsecondary level and discusses ways in which assistive technology enhances learning. Additionally, an overview of legislation that has had an impact on assistive technology at the postsecondary level is presented. Issues involving assistive technology programs at the postsecondary level are discussed. Postsecondary assistive technology program components, device selection, and training guidelines also are outlined.

Adolescent↗
PubMed1992

Outcome of gestational diabetes in Bengali Asians living in an east London health district.

The characteristics and outcome of pregnancy complicated by gestational glucose intolerance are described in a consecutive series of 69 Bengali Asian patients and a parallel group of 22 Caucasian patients. The Bengali patients were older and of higher parity than the Caucasians and more frequently required insulin therapy. However, the outcome of pregnancy was similar in terms of antenatal clinic attendance, the number of antenatal hospital admissions, glycaemic control, birthweight and mode of delivery. Of those patients who attended for postnatal glucose tolerance test, 20% of the Bengali population demonstrated persisting abnormality of glucose tolerance, whereas no abnormalities were evident in the Caucasian group. These findings are consistent with the high prevalence and early age of onset of non-insulin-dependent diabetes in Asian populations. The World Health Organisation (WHO) criteria for the diagnosis of impaired glucose tolerance proved insufficiently sensitive for the diagnosis of gestational diabetes. This was particularly demonstrated by four patients with apparently normal glucose tolerance by WHO criteria who subsequently required insulin therapy.

Adult↗
PubMed1992

Symmetry in building block design for learning disabled and nonlearning disabled boys.

This study examined perceptual differences in symmetry with and without a model between 21 learning disabled boys with reading deficits and 28 learning disabled boys with deficits in mathematics. 55 nonlearning disabled boys served as controls. All boys were in Grades 3, 4, or 5. Without a model, all learning disabled boys built significantly more asymmetrical building block designs than nonlearning disabled boys. However, with a model, all learning disabled boys could imitate the model, but it took them longer to complete the task successfully. All boys appeared to have difficulty in modeling asymmetrical tasks, taking more time for task completion after seeing an asymmetrical model. This study suggests modeling perceptual tasks might be an effective teaching strategy for such children.

Attention↗
PubMed1985

Targeting services to chronically disabled elderly: the preliminary experiences of the National Long Term Care Channeling Demonstration.

In response to concerns about the adequate provision of long term care, the National Long Term Care Channeling Demonstration has been funded by the Department of Health and Human Services. The project is designed to provide coordinated community services as an alternative to institutionalization to those elderly individuals at risk of placement. This preliminary work examines the demonstration's experience in its attempt to target services to these individuals. Although final research results are not yet available, the method, problems, and results of the initial case finding and screening approaches provide additional knowledge concerning the targeting experience.

Aged↗
PubMed1979

Ovarian responses of pregnant mare serum gonadotropin- and human chorionic gondotropin-primed rats: desensitizing, luteolytic, and ovulatory effects of a single dose of human chorionic gonadotropin.

We conducted a study to determine the morphological appearance and functional responsiveness of ovarian tissues after administration of hCG to 28-day-old rats primed 65 h earlier with PMS gonadotropin (PMSG) and after administration of a second dose of hCG 5 days later, i.e. to 33-day-old rats containing heavily luteinized ovaries. Sixty-five hours after the administration of 50 IU PMSG sc to 25-day-old rats, ovaries already contained an abundance of luteinized follicles and an adenylyl cyclase (AC) system that was responsive to LH, epinephrine, and NaF. The administration of 50 IU hCG sc at this time initially resulted in a loss of LH-responsive ovarian AC. Within 4 days of the hCG injection, the ovaries of the now 32-day-old rats were heavily luteinized, and ovarian AC was highly responsive to LH, epinephrine, and NaF. The administration of a single sc dose of 200 IU hCG to 33-day-old PMSC- and hCG-primed rats with luteinized ovaries resulted in a rapid desensitization of the ovarian AC to LH and a drop in serum progesterone levels, During the subsequent 7 days, serum progesterone levels continued to decline, while total ovarian AC reacquired responsiveness to LH by days 4--5 after the densensitizing dose of hCG. Dissection of ovarian components revealed, however, that the AC system of the corpora lutea originally present at the time of the second hCG injection remained permanently refractory to LH and that the AC in corpora lutea newly formed from freshly ovulated follicles exhibited a significant responsiveness to LH, epinephrine, and NaF. However, these new corpora lutea were not fully active, since serum progesterone never rose. Subcutaneous administration of 50 IU hCG to 33-day-old PMSG- and hCG-primed rats also promoted a rapid loss of AC responsiveness to LH. This lower concentration of hCG was not sufficient to promote follicular development or ovulation, and the ovarian AC remained refractory to LH for at least 7 days. Intravenous administration of 75 IU hCG to 33-day-old PMSG- and hCG-primed rats similarly promoted a rapid and permanent loss of luteal AC responsiveness to LH; again, follicles did not mature to a preovulatory state and, in fact, appeared to undergo atresia rather than ovulation. These results indicate that in heavily luteinized ovaries 1) hCG promotes desensitization of rat luteal AC to LH, 2) Desensitization of AC to LH stimulation in corpora lutea is permanent and irreversible, and 3) only under conditions where follicles mature and ovulate and new corpora lutea are formed does total ovarian AC reacqure responsiveness during the subsequent week.

Adenylyl Cyclases↗