Biomedical subjects

Kathryn Davis

Publications and source records attributed to Kathryn Davis.

9 recordsLinked to original sources

PubMed2006

Platelets photochemically treated with amotosalen HCl and ultraviolet A light correct prolonged bleeding times in patients with thrombocytopenia.

BACKGROUND: Photochemical treatment (PCT) with amotosalen HCl with ultraviolet A illumination inactivates pathogens and white blood cells in platelet (PLT) concentrates. STUDY DESIGN AND METHODS: In a Phase II crossover study, 32 patients with thrombocytopenia received one transfusion of PCT and/or one transfusion of untreated (reference) apheresis PLTs. Hemostatic efficacy was assessed with the cutaneous template bleeding time and clinical observations. RESULTS: Paired bleeding time data for PCT and reference transfusions were available for 10 patients. Mean pretransfusion bleeding times were 29.2 +/- 1.6 minutes in the PCT group and 28.7 +/- 2.5 minutes in the reference group. After transfusion of a dose of PLTs of at least 6.0 x 10(11), mean 1-hour posttransfusion template bleeding times corrected to 19.3 +/- 9.5 minutes in the PCT group and 14.3 +/- 6.5 minutes in the reference group (p = 0.25). In 29 patients receiving paired PCT and reference transfusions, mean 1-hour posttransfusion PLT count increments were 41.9 x 10(9) +/- 20.8 x 10(9) and 52.3 x 10(9) +/- 18.3 x 10(9) per L for PCT and reference, respectively (p = 0.007), and mean 1-hour posttransfusion PLT corrected count increments (CCIs) were 10.4 x 10(3) +/- 4.9 x 10(3) and 13.6 x 10(3) +/- 4.3 x 10(3) for PCT and reference, respectively (p < 0.001). The time to next PLT transfusion was 2.9 +/- 1.2 days after PCT transfusions versus 3.4 +/- 1.3 days after reference transfusions (p = 0.18). Clinical hemostasis was not significantly different after PCT and reference transfusions. CONCLUSION: PCT PLTs provided correction of prolonged bleeding times and transfusion intervals not significantly different than reference PLTs despite significantly lower PLT count increments and CCIs.

Adolescent↗

PubMed2005

Factors affecting posttransfusion platelet increments, platelet refractoriness, and platelet transfusion intervals in thrombocytopenic patients.

A variety of patient and product-related factors influenced the outcome of 6379 transfusions given to 533 patients in the Trial to Reduce Alloimmunization to Platelets (TRAP). Responses measured were platelet increments, interval between platelet transfusions, and platelet refractoriness. Patient factors that improved platelet responses were splenectomy and increasing patient age. In contrast, at least 2 prior pregnancies, male gender, splenomegaly, bleeding, fever, infection, disseminated intravascular coagulation, increasing height and weight, lymphocytotoxic antibody positivity, an increasing number of platelet transfusions, or receiving heparin or amphotericin were associated with decreased posttransfusion platelet responses. Platelet factors that were associated with improved platelet responses were giving ABO-compatible platelets, platelets stored for 48 hours or less, and giving large doses of platelets while ultraviolet B (UV-B) or gamma irradiation decreased platelet responses. However, in alloimmunized lymphocytoxic antibody-positive patients, the immediate increment to UV-B-irradiated platelets was well maintained, whereas all other products showed substantial reductions. Refractoriness to platelet transfusions developed in 27% of the patients. Platelet refractoriness was associated with lymphocytotoxic antibody positivity, heparin administration, fever, bleeding, increasing number of platelet transfusions, increasing weight, at least 2 pregnancies, and male gender. The only factors that reduced platelet refractoriness rates were increasing the dose of platelets transfused or transfusing filtered apheresis platelets.

Blood Platelets↗

PubMed2004

Therapeutic efficacy and safety of platelets treated with a photochemical process for pathogen inactivation: the SPRINT Trial.

We report a transfusion trial of platelets photochemically treated for pathogen inactivation using the synthetic psoralen amotosalen HCl. Patients with thrombocytopenia were randomly assigned to receive either photochemically treated (PCT) or conventional (control) platelets for up to 28 days. The primary end point was the proportion of patients with World Health Organization (WHO) grade 2 bleeding during the period of platelet support. A total of 645 patients (318 PCT and 327 control) were evaluated. The primary end point, the incidence of grade 2 bleeding (58.5% PCT versus 57.5% control), and the secondary end point, the incidence of grade 3 or 4 bleeding (4.1% PCT versus 6.1% control), were equivalent between the 2 groups (P =.001 by noninferiority). The mean 1-hour posttransfusion platelet corrected count increment (CCI) (11.1 x 10(3) PCT versus 16.0 x 10(3) control), average number of days to next platelet transfusion (1.9 PCT versus 2.4 control), and number of platelet transfusions (8.4 PCT versus 6.2 control) were different (P <.001). Transfusion reactions were fewer following PCT platelets (3.0% PCT versus 4.4% control; P =.02). The incidence of grade 2 bleeding was equivalent for PCT and conventional platelets, although posttransfusion platelet count increments and days to next transfusion were decreased for PCT compared with conventional platelets.

Adolescent↗

PubMed2004

Positive and negative network correlations in temporal lobe epilepsy.

Temporal lobe seizures are accompanied by complex behavioral phenomena including loss of consciousness, dystonic movements and neuroendocrine changes. These phenomena may arise from extended neural networks beyond the temporal lobe. To investigate this, we imaged cerebral blood flow (CBF) changes during human temporal lobe seizures with single photon emission computed tomography (SPECT) while performing continuous video/EEG monitoring. We found that temporal lobe seizures associated with loss of consciousness produced CBF increases in the temporal lobe, followed by increases in bilateral midline subcortical structures. These changes were accompanied by marked bilateral CBF decreases in the frontal and parietal association cortex. In contrast, temporal lobe seizures in which consciousness was spared were not accompanied by these widespread CBF changes. The CBF decreases in frontal and parietal association cortex were strongly correlated with increases in midline structures such as the mediodorsal thalamus. These results suggest that impaired consciousness in temporal lobe seizures may result from focal abnormal activity in temporal and subcortical networks linked to widespread impaired function of the association cortex.

Adolescent↗

PubMed2004

Recovery and life span of 111indium-radiolabeled platelets treated with pathogen inactivation with amotosalen HCl (S-59) and ultraviolet A light.

BACKGROUND: A photochemical treatment (PCT) method to inactivate pathogens in platelet concentrates has been developed. The system uses a psoralen, amotosalen HCl, coupled with ultraviolet A (UVA) illumination. STUDY DESIGN AND METHODS: Three sequential clinical trials evaluated viability of PCT platelets prepared with a prototype device. Posttransfusion recovery and lifespan of (111)Indium-labeled autologous 5 day-old platelets in healthy subjects was assessed. In the first study, 23 subjects received transfusions of autologous PCT and/or control platelets. In a second study, 16 of these subjects received PCT platelets processed with a Compound Adsorption Device (CAD) (PCT-CAD) to reduce patient exposure to residual amotosalen. In the third study, the effect of gamma-irradiation on PCT platelets was studied. Data from control transfusions from Study A were used for paired comparisons in the latter 2 studies. RESULTS: Mean PCT-CAD platelet recovery for the 16 subjects with paired data was 42.5 +/- 8.7% versus 50.3 +/- 7.7% for control platelets, mean difference of 7.8% (p < 0.01). Mean lifespan for PCT-CAD platelets was 4.8 days (+/-1.3) versus 6.0 days (+/-1.2) for control platelets, mean difference of 1.3 days (p < 0.01). Platelet recovery and lifespan were similar to PCT-CAD for PCT without CAD treatment and PCT-CAD with gamma-irradiation. CONCLUSION: Viability of 5 day-old PCT platelets was less than for control platelets. However, both were within ranges reported for 5 day-old platelets.

Adolescent↗

PubMed2004

Observing and engaging in purposeful actions with objects influences estimates of their size.

A ladle was recalled as being taller by participants who observed tedious removal of sand from it with a small teaspoon than by those who observed removal with a larger spoon. A second experiment showed that the number of darts thrown in order to hit a target correlated negatively with memory estimates of the size of the target, a finding replicated in a third experiment with size estimates made while the target was visible. The first two experiments suggest that the way an object is used can influence memory of its size. The third experiment supports the hypothesis that in vivo size estimation of familiar objects may employ a mechanism that derives size from memory and that size memory can be distorted by the way an object was used.

Female↗

PubMed2003

Pelvic floor dysfunction: a conceptual framework for collaborative patient-centred care.

BACKGROUND: Pelvic floor dysfunction is a disorder predominantly affecting females. It is common and undermines the quality of lives of at least one-third of adult women and is a growing component of women's health care needs. Identifying and supporting these needs is a major public health issue with a strong psychosocial and economic basis. The importance of the interdependence of mechanical, neural, endocrine and environmental factors in the development of pelvic floor dysfunction is well recognized. There is a paucity of data investigating the true prevalence, incidence, specific risk factors, poor outcome of treatment and subsequent prevention strategies for women with multiple pelvic floor symptomatology. AIM: The aim of this paper is to present a critical review of the literature on the mechanism, presentation and management of multiple symptomatology in pelvic floor dysfunction and to propose a conceptual framework by which to consider the impact and problems women with pelvic floor dysfunction face. METHODS: A comprehensive although not exhaustive literature search was carried out using medical and nursing databases BIOMED (1966-2002) NESLI (1989-2002) and EMBASE (1980-2003) CINAHL (1982-2003) and Cochrane databases using the key words 'pelvic floor dysfunction', 'incontinence (urinary and faecal)', 'genital prolapse', sexual dysfunction, 'aetiology', epidemiology' and 'treatment'. Retrospective and prospective studies and previous clinical reviews were considered for review. The articles retrieved were hand searched for further citations and referrals were made to relevant textbooks. Particular attention was paid to papers that focused on multiple pelvic floor symptoms. FINDINGS: Pelvic floor dysfunction affects women of all ages and is associated with functional problems of the pelvic floor. Pelvic floor dysfunction describes a wide range of clinical problems that rarely occur in isolation. Inaccurate knowledge, myths and misconceptions of the incidence, cause and treatment of pelvic floor dysfunction abound. Given the significance of the aetiological contribution of factors such as pregnancy and obstetric trauma, ageing, hormonal status, hysterectomy and lifestyle in the development of pelvic floor disorders, the assessment, management and prevention of pelvic floor dysfunction remains a neglected part of many health care professionals educational preparation. This not only has major economic but also psychosocial implications for women, the general population and women's health care providers. A conceptual framework is also discussed that considers not only the impact and difficulties women with pelvic floor dysfunction face but also areas in which health care professionals can improve assessment and eventual treatment outcomes. CONCLUSION: This paper demonstrates gaps in the current provision of women's health care services. Functional pelvic floor problems are perceived to have low priority compared with other health disorders, and treatment remains sub-optimal. Inherent in achieving and promoting better health care services for women is the need for better collaborative approaches to care. There is a need to identify and develop comprehensive interdisciplinary, multi-professional strategies that improve the assessment and treatment of pelvic floor dysfunction in primary, secondary and tertiary settings. If this area of women's health care is to be improved nurses, whether community- or hospital-based, must play a front-line role in challenging and changing current practices. Education needs to be given greater priority and the development of a specialist pelvic floor nurse role explored. Such strategies could substantially influence a more effective approach to women's health care needs, result in improved treatment outcomes and liberate women from the embarrassment, social and sexual isolation, restriction to employment and leisure opportunities and potential loss of independence that multiple symptomatology can generate.

Fecal Incontinence↗

PubMed2003

Factors influencing moderate to severe reactions to PLT transfusions: experience of the TRAP multicenter clinical trial.

BACKGROUND: During the Trial to Reduce Alloimmunization to Platelets (TRAP Trial), data were prospectively collected for 8769 PLT transfusions regarding the frequency of moderate to severe PLT transfusion reactions. STUDY DESIGN AND METHODS: At seven centers, 598 patients were randomly assigned to receive unmodified pooled random-donor PLT concentrates (PCs), UV-B-irradiated PCs, filtered PCs, or filtered random-donor apheresis PLTs. RESULTS: Moderate to severe transfusion reactions were an increase in temperature of at least 2 degrees C, chills with rigors, extensive urticaria, dyspnea, cyanosis, or bronchospasm. These reactions occurred with 2.2 percent of the transfusions in 22 percent of the patients. Transfusion reactions were associated with WBC counts of more than 5 x 10(6) per transfusion (p = 0.002) and transfusions stored for more than 48 hours (p = 0.02). PLT counts before transfusion were significantly lower for transfusions associated with reactions (p = 0.005). Neither UV-B irradiation nor apheresis PLTs independently influenced reaction rates. The PLT increment at 1 hour after transfusion was lower for transfusions associated with reactions (p = 0.004), and the frequency of reactions was higher in PLT refractory patients (p < 0.001). CONCLUSIONS: The provision of either fresh and/or WBC-reduced PLTs may decrease the frequency of PLT transfusion reactions and improve PLT transfusion efficacy.

Adult↗

PubMed2002

Transfusion of pooled buffy coat platelet components prepared with photochemical pathogen inactivation treatment: the euroSPRITE trial.

A nucleic acid-targeted photochemical treatment (PCT) using amotosalen HCl (S-59) and ultraviolet A (UVA) light was developed to inactivate viruses, bacteria, protozoa, and leukocytes in platelet components. We conducted a controlled, randomized, double-blinded trial in thrombocytopenic patients requiring repeated platelet transfusions for up to 56 days of support to evaluate the therapeutic efficacy and safety of platelet components prepared with the buffy coat method using this pathogen inactivation process. A total of 103 patients received one or more transfusions of either PCT test (311 transfusions) or conventional reference (256 transfusions) pooled, leukoreduced platelet components stored for up to 5 days before transfusion. More than 50% of the PCT platelet components were stored for 4 to 5 days prior to transfusion. The mean 1-hour corrected count increment for up to the first 8 test and reference transfusions was not statistically significantly different between treatment groups (13,100 +/- 5400 vs 14,900 +/- 6200, P =.11). By longitudinal regression analysis for all transfusions, equal doses of test and reference components did not differ significantly with respect to the 1-hour (95% confidence interval [CI], -3.1 to 6.1 x 10(9)/L, P =.53) and 24-hour (95% CI, -1.3 to 6.5 x 10(9)/L, P =.19) posttransfusion platelet count. Platelet transfusion dose, pretransfusion storage duration, and patient size were significant covariates (P <.001) for posttransfusion platelet counts. Clinical hemostasis, hemorrhagic adverse events, and overall adverse events were not different between the treatment groups. Platelet components prepared with PCT offer the potential to further improve the safety of platelet transfusion using technology compatible with current methods to prepare buffy coat platelet components.

Adult↗