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Biomedical subjects

S Parker

Publications and source records attributed to S Parker.

At least 73 records · Page 4Linked to original sources
PubMed1999

Evidence of correction of open bite malocclusion using active vertical corrector treatment.

This study used a cephalometric analysis that isolated tipping and bodily tooth movements of the upper and the lower incisors and measured vertical skeletal changes in the anterior region of the maxilla and mandible to evaluate the outcome of two-phase nonextraction treatment for open bite malocclusion. Twenty-nine subjects treated with an active vertical corrector (AVC) followed by fixed 022 orthodontic appliances were selected by one orthodontist from his private practice. All subjects lacked vertical incisor contact at the start of treatment and had adequate initial, end of phase 1, and deband lateral cephalograms. Each subject in the treated group was matched by age and sex with an untreated subject from the Broadbent Bolton Collection, Cleveland, OH. Data were collected for three time intervals; phase 1 treatment with the AVC (T1 to T2), phase 2 fixed-appliance treatment (T2 to T3), and over the total treatment period (T1 to T3). Analysis of the data showed no statistically significant (P < or = .002) changes between treated subjects and controls for any variables during the phase 1 (T1 to T2) or phase 2 (T2 to T3) treatment intervals. However, overbite was significantly improved compared with controls (P < or = .002) during the T1 to T3 time interval. It was concluded that two-phase treatment with the AVC followed by fixed orthodontic appliance treatment results in a statistically significant increase in incisor overbite. The observed increase in overbite was the result of small but clinically significant changes in relative mandibular vertical growth, bodily incisor movement toward the occlusal plane, and lingual tipping of the lower incisors.

Adolescent↗
PubMed1999

Experience with transdermal testosterone replacement therapy for hypogonadal men.

BACKGROUND: None of the existing options for long-term testosterone replacement therapy (TRT) for hypogonadal men are ideal. Depot replacement at frequent intervals and implants are effective but invasive and inconvenient for the patient. Oral therapy results in poor hormone levels. Both are associated with undesirable metabolic changes. A transdermal formulation therefore represents a potential therapeutic advance for testosterone replacement. OBJECTIVE: To carry out a clinical audit of the acceptability and efficacy as a treatment for hypogonadism of the first transdermal testosterone therapy available in the UK (Andropatch, SmithKline Beecham) compared with existing androgen replacement options. PATIENTS AND MEASUREMENTS: Serum testosterone and questionnaire data on treatment efficacy, side-effects, therapy preference, sexual dysfunction and partner's attitudes to therapy were obtained from 50 hypogonadal men prescribed long-term testosterone replacement. RESULTS: Eighty per cent of the men returned analysable questionnaires. Eighty-four per cent experienced adverse effects with transdermal therapy, most commonly dermatological problems; 22% of the sample elected to continue with transdermal therapy, 72% returned to depot and 5% returned to oral therapy. The reservoir patches were judged to be too large, uncomfortable, visually obtrusive and noisy. Testosterone levels were comparable to those obtained with depot replacement with the added advantage of a more physiological pharmacokinetic profile. Men taking oral preparations were consistently under-replaced. CONCLUSIONS: Adverse events were substantially higher than reported from clinical trials but in keeping with the spectrum of yellow card reports received by the Committee on Safety of Medicines. The pharmacokinetic advantages are thus largely outweighed by low patient acceptability. In its present form transdermal therapy remains an expensive option for those who cannot tolerate depot testosterone replacement.

Administration, Cutaneous↗
PubMed1999

Seroprevalence of cytomegalovirus infection among children and females in Ankara, Turkey, 1995.

BACKGROUND: Cytomegalovirus (CMV) is the most frequent known cause of congenital viral infections in humans. Cytomegalovirus is endemic throughout the world, affecting most of the population where the seroprevalence of CMV IgG is known to vary among countries. METHODS: The present study was designed to show the prevalence of CMV antibodies among children aged 1 day to 15 years and women of child-bearing age in Ankara, Turkey. Antibodies to CMV were analyzed in serum samples of 318 children and 745 women using a passive particle-agglutination test. RESULTS: The overall prevalence of CMV antibodies was 90.6% among children and 99% among women aged 15-49 years. The difference between stratified age groups was not statistically significant (chi 2 = 4.92, P = 0.177) in either children or females. CONCLUSIONS: Our findings confirm that CMV is very prevalent in Turkey and is at the higher end of worldwide ranges. Using the results of the present study, the transmission mode of CMV infection and the risk for congenital CMV infection are discussed. We have come to the conclusion that the risk of fetal infection in Turkey cannot be predicted; however, most CMV infections in the first year of life are transmitted from mother to infant and this is the main source of infection in Turkey.

Adolescent↗
PubMed1999

Validation and characterization of a human volunteer challenge model for cholera by using frozen bacteria of the new Vibrio cholerae epidemic serotype, O139.

Until recently, all epidemic strains of Vibrio cholerae were of the O1 serotype. Current epidemics have also been caused by a new serotype, Vibrio cholerae O139. Although the pathogenesis and clinical features of O139 cholera are similar to those of O1 cholera, immunity to serotype O1 does not confer immunity to serotype O139. Therefore, prior to beginning vaccine efficacy studies, we sought to validate the use of a large standardized frozen inoculum of virulent V. cholerae O139 4260B for use in a human volunteer challenge model. Healthy volunteers (n = 25) were recruited for an Internal Review Board-approved inpatient dose-escalation challenge. Our goal was to identify a dose at which the cholera attack rate and the geometric mean purge were sufficient for determining vaccine efficacy against moderate and severe disease. At a dose of 10(5) CFU, 8 of 10 volunteers experienced purging and had a positive stool culture for V. cholerae. However, at this dose, the geometric mean stool volume of 2,175 g was insufficient by study criteria. At a dose of 10(6) CFU, 14 of 15 volunteers experienced purging, with a geometric mean stool volume of 5,621 g. Disease severity was significantly greater in volunteers with blood group O than those with non-O blood types (10,353 g versus 3,555 g, P < 0.001). Following challenge, all volunteers demonstrated a significant rise in antitoxin antibodies but the serum vibriocidal titer was attenuated compared to that seen after challenge with an O1 strain. This model provides a reproducible illness of sufficient severity for testing the efficacies of new O139 or combined O1-O139 vaccines.

Antibodies, Bacterial↗
PubMed1998

The second domain of the CD45 protein tyrosine phosphatase is critical for interleukin-2 secretion and substrate recruitment of TCR-zeta in vivo.

The CD45 protein tyrosine phosphatase (PTPase) has been shown to regulate the activity of Lck and Fyn protein tyrosine kinases in T cells. However, it is not clear that these constitute the only CD45 substrates. Moreover, the manner by which PTPase activity and substrate recruitment are regulated, is poorly understood. Previous in vitro studies suggest that the first cytoplasmic PTPase domain (D1) of CD45 is the active PTPase, which may be regulated by an enzymatically inactive second PTPase domain (D2). However, the function of CD45 D2 in vivo is unknown. In this study, reconstitution of CD45(-) T cells with specific CD45 PTPase mutants allowed demonstration of a critical role for D2 in TCR-mediated interleukin (IL)-2 production. Specifically, replacement of CD45 D2 with that of the LAR PTPase to form a CD45/LAR:D2 chimera, abrogates CD45-dependent IL-2 production. This effect cannot be accounted for by loss of PTPase activity per se. The expression of D1 substrate-trapping mutants reveals an in vivo interaction between CD45 and TCR-zeta that is dependent on CD45 D2. Thus, cells expressing CD45 lacking D2 exhibit abnormal TCR-mediated signaling characterized by hyperphosphorylation of zeta and deficient ZAP-70 phosphorylation. These data suggest an essential role for CD45 D2 in TCR-regulated IL-2 production through substrate recruitment of the zeta chain.

Humans↗
PubMed1998

A case of treatment-refractory psychosis responsive to sertindole.

Sertindole is an antipsychotic with atypical in vitro and ex vivo binding profiles and little propensity to cause extrapyramidal symptoms. However, its potential usefulness in the treatment of psychosis resistant to the 'classical' neuroleptics has not been determined. In the present study we used a double blind, placebo-controlled trial of sertindole and observed dramatic, sustained resolution of formerly-chronic positive and negative psychotic symptoms in a schizophrenic patient. This patient had averaged 2.5 inpatient admissions per year for the 8 years preceding initiation of sertindole therapy, but has had no hospitalizations or psychosis in the 3.5 years since. Improved cognitive function has also been documented. This preliminary, but controlled, experience suggests that sertindole may possess a spectrum of clinical activity distinct from that of the typical antipsychotic agent.

Adult↗
PubMed1998

Evaluating the effect of soft lining materials on the growth of yeast.

STATEMENT OF PROBLEM: Soft lining materials continue to have a place in clinical removable prosthodontics. However, there is an increased probability of yeast colonization on soft lining materials. PURPOSE: This study (1) assessed a method of evaluating the effect of long-term soft lining materials on the growth of yeast and (2) investigated the effect five soft lining materials had on the growth of three species of yeast. MATERIAL AND METHODS: Coe Supersoft, Novus, and three experimental soft lining materials were investigated together with Candida albicans, Candida tropicalis, and Issatchenkia orientalis (formerly Candida krusei) yeasts. Strips of soft lining material incubated on blood agar plates were examined for inhibition of the growth of yeast. Soft lining materials soaked in sterile trypticase soya broth or water were inoculated with yeast and incubated. The change in colony forming units per milliliter from the initial load of yeast at 3 days was measured. Statistical analysis was performed with an independent paired Student t test. RESULTS: Inhibition of yeast growth occurred for two soft lining materials. Despite the presence of sufficient viable organisms, differences between the initial load of yeast and the 3-day results were mostly small, both for the test and control groups, suggesting that the material does not support the growth of the tested yeast during this period. CONCLUSIONS: The often described increased prevalence of yeast associated with soft lining materials in the oral environment is likely related to readily available nutrients in the mouth and the difficulty in maintaining and cleaning these materials.

Acrylic Resins↗
PubMed1998

Adhesion and tear energy of a long-term soft lining material activated by rapid microwave energy.

STATEMENT OF PROBLEM: Construction of dentures with permanent soft linings is time-consuming in the laboratory and extra costs are related to equipment and materials used. PURPOSE: The purpose of this in vitro study was to determine whether using microwave energy to activate the polymerization of a silicone rubber denture soft lining material affected its properties. MATERIAL AND METHODS: Tear energy and adhesive properties were measured in a tensile testing machine by using a pants leg tear test and peel specimens. Tear energy was measured for specimens polymerized conventionally (control) and for 3, 5, and 10 minutes in a microwave. Data were analyzed with one-way analysis of variance and a two-sample Student t test. RESULTS: The multiple comparison test failed to show a significant difference in tear energy between 3 minutes microwave activation and conventional heat curing. However, 3 minutes microwave activation revealed a significantly stronger material when compared with 5 minutes and 10 minutes (p < 0.05). Application of a two-sample Student t test failed to demonstrate a significant difference between microwave energy and conventional heat activation groups in the adhesion test. In adhesion testing, all specimens presented cohesive failure. CONCLUSIONS: This method of polymerization does not compromise the strength of a soft lining material and its adhesion to polymethyl methacrylate. This study suggests the use of 3 minutes 650 W microwave energy for processing a silicone soft lining material.

Adhesiveness↗
PubMed1998

Soft acrylic resin materials containing a polymerisable plasticiser I: mechanical properties.

Conventional soft acrylic resin materials depend on the use of plasticisers for their compliance. In aqueous environments the plasticisers leach out causing the material to harden. Use of a polymerisable plasticiser has been shown to solve this problem. One such material was developed but failed mechanically during clinical trial. The aim of this study was to reformulate to produce a material with improved strength. Three different methacrylate monomers were used with two different levels of plasticiser, each monomer mix was used with the same copolymer powder at three powder/liquid ratios. Tensile strength, tear energy and hardness were measured and results compared with 'Supersoft', a proprietary plasticised acrylic resin soft lining material. All the experimental materials had a higher tensile strength than the original Parker/Braden material. The 30% plasticiser materials with the higher powder/liquid level had strength, tear energy and hardness values in the same range as 'Supersoft'. Materials of improved strength have been produced.

Acrylic Resins↗
PubMed1998

Catching goldfish: quality in qualitative research.

This paper reviews the contribution of qualitative methods to health services research (HSR) and discusses some of the issues involved in recognizing quality in such work. The place of qualitative work is first defined by reference to Archie Cochrane's agenda for HSR and the limitations of the recent focus on randomized trials as the standard method. Health care practice involves large elements of improvisation which cannot be captured by evidence-based approaches. Qualitative methods offer ways of understanding this improvisation and of identifying more efficient and effective practices, as well as considering the traditional topics of equity and humanity. The methodological procedures of qualitative work reflect a long-established inductive tradition in scientific practice. The logic of grounded theory provides a contemporary specification. In its application, it is quite different from the methodological anarchy of postmodernism. The use of qualitative research and the theoretically stated generalizations which arise from it inform reflective work by health service managers, planners and clinicians.

Evidence-Based Medicine↗
PubMed1998

Listening to parents. A national survey of parents with young children.

OBJECTIVE: To document the child-rearing needs and pediatric health care experiences of parents with children from birth to 3 years old. DESIGN: A nationally representatives sample of 2017 parents with children younger than 3 years using a 25-minute structured telephone questionnaire. Interviews were completed by 68% of the screened eligible respondents. The margin of sampling error for results at the 95% confidence level was +/- 3 percentage points. RESULTS: Seventy-six percent of children younger than 3 years were reported by parents to be in excellent health; 88% had a regular source of pediatric health care. Seventy-one percent of parents who received special pediatric services rated their child's physician as excellent in providing good health care. Seventy-nine percent of parents reported they could use more information in at least 1 of 6 areas of child rearing, and 53% wanted information in at least 3 areas. Forty-two percent had talked with their child's physician about "nonmedical" concerns; 39% of parents read to or looked at a picture book with their child on a daily basis; 51% of parents set daily routines for meals, naps, and bedtime. Breast-feeding and reading to the child on a daily basis were much more likely if a physician encouraged parents to do so. CONCLUSIONS: Most parents view the pediatric health care system as meeting the physical health needs of their young children. Parents want more information and support on child-rearing concerns, yet pediatric clinicians often fail to discuss nonmedical questions with them. The interventions of pediatric clinicians can positively affect parental behavior. Pediatric practices should consider creative ways to reconstitute and augment their current services and systems of care.

Adult↗