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Biomedical subjects

H Dixon

Publications and source records attributed to H Dixon.

At least 19 recordsLinked to original sources
PubMed2005

Mucosal delivery of cytotoxic therapeutic agents: response of rat nasal mucosa to microencapsulated ethopropazine HCl enantiomer.

Use of microencapsulation technology in combination with absorption enhancers eliminated epithelium irritation and necrosis commonly associated with nasal delivery of cytotoxic therapeutic agents. Phenothiazines, such as ethopropazine (ETZ), promethazine, trimeprazine and propiomazine have been used for the treatment of allergenic conditions, motion sickness, nausea, Parkinson's disease, Prion disease and as a sedative for psychiatric disorders. The enantiomers of commercially available racemic phenothiazines were isolated and purified using classical diastereomeric salt techniques. The racemate and the enantiomers of ETZ were tested in vitro for their cellular toxicity using lung fibroblast cells. Each enantiomer was shown to be cytotoxic at concentrations greater than 10(-5) molar. The ETZ enantiomers were encapsulated using spinning disk atomization to prepare a nasal delivery dosage form that does not produce an irritation response. Release rates for the ETZ microcapsules were determined in vitro and an animal study was conducted to determine the irritation response of rat nasal mucosa when dosed with encapsulated vs. non-encapsulated ETZ.

Animals↗
PubMed2003

Does receiving a copy of correspondence improve patients' satisfaction with their out-patient consultation?

It is standard practice to write to a patient's general practitioner (GP) following an out-patients consultation. This study set out to assess whether sending a copy of this letter to the patient improves their satisfaction with the consultation. Two hundred patients were randomly assigned to receive or not to receive a copy of their GP letter. Their satisfaction was then assessed by means of a postal questionnaire. The two groups were compared to ensure that their was no significant difference between them with regard to any other aspect of their consultation. Those who did not receive a copy letter had a median overall satisfaction score of 7.75 whilst those who did had a median score of 9.0 (p = 0.014). The only other factors predictive of overall satisfaction were receiving an explanation of the problem and spending sufficient time with the doctor. Sending patients a copy of correspondence to their GP is one means of aiding communication and improving overall satisfaction.

Correspondence as Topic↗
PubMed2001

The Breast Cancer Distance Education Program: development and evaluation of a course for specialist breast care nurses.

The Breast Cancer Distance Education Program is the first tertiary-based education program for specialist breast care nurses in Australia. The program covers current treatment options, psychosocial issues, and professional development issues relating to breast cancer nursing. For the first two student intakes (n = 53), precourse, postcourse, and 3-month follow-up surveys were conducted to assess the perceived value of the course, identify any limitations, and note changes in practice that arose. Before taking the course, most of the students had experience in breast cancer nursing, but lacked confidence and hoped to learn more about responding effectively to psychosocial issues through communication, counseling, and provision of support to patients and their carers. After taking the course, the students were very positive about the course content, resources, and teaching support. They reported learning new skills for addressing psychosocial issues and symptom management arising from a diagnosis of breast cancer, stating a desire to implement these new skills. Comparison between results from the three surveys indicated that students' confidence in providing breast cancer support increased significantly in most areas of practice, and was maintained at 3-month follow-up survey. Results suggest that students met the course objectives successfully, and in most cases subsequently translated their knowledge into improved practice.

Adult↗
PubMed2000

Personal Dental Services--a practitioner's point of view.

NHS dentistry has seen many changes recently. The latest has been the introduction of Personal Dental Services. This article describes the experiences of two general dental practitioners in their practice who entered as a first wave pilot. The article explains the steps involved in generating a proposal and preparing a practice to run as a pilot. The authors have highlighted areas of particular concern for others to consider before embarking on a similar journey.

Costs and Cost Analysis↗
PubMed2000

Metal-oxide nanoparticles for the reinforcement of dental restorative resins.

Metal oxide nanoparticles were synthesized from tantalum ethoxide and zirconium isopropoxide and subsequently surface grafted with vinyl silane and silyl methacrylate coupling agents. The nanoparticles were then dispersed into a commercial dental resin, and the composite was photocured into rigid three-point bend and fracture toughness specimens. The optically transparent/translucent cured composites demonstrated strength, toughness, and elastic modulus inferior to the unfilled material. Therefore, modifications in surface functionalization are being made to improve coupling and reduce interparticle associations.

Biocompatible Materials↗
PubMed1999

Sun protection and sunburn in primary school children: the influence of age, gender, and coloring.

BACKGROUND: Childhood is a high-risk period for skin damage due to excessive sun exposure. This damage may lead to skin cancer later in life. METHODS: The present study measured children's knowledge and attitudes, and reported usual behavior relevant to sun protection and parents' encouragement of their children's sun protection among a sample of 735 primary school students and their parents, in Victoria, Australia. The incidence of sunburn among the children over late spring and early summer was monitored weekly for 8 weeks. RESULTS: The results indicate that children's knowledge of sun protection is moderately high and that positive sun protection attitudes, reported frequency of parents encouraging protection, and children carrying out sun protection are generally high. Trends for age indicate that while knowledge of sun protection increases with age, attitudes and behaviors supportive of sun protection decline. Sunburn rates increase with age. There was some evidence to suggest that children with fairer coloring receive greater encouragement from parents to protect themselves and are marginally better protected than children with darker coloring. However, this highly susceptible group still suffers more burns. There was little variation based on children's gender. CONCLUSIONS: The mid-primary school years may be a critical time for interventions promoting sun protection.

Adolescent↗
PubMed1999

Comparison of albumin versus bicarbonate treatment for neonatal metabolic acidosis.

UNLABELLED: In this study the effectiveness of 4.5% human albumin was compared with 4.2% sodium bicarbonate for neonatal metabolic acidosis, using a randomised controlled trial. The change in median pH following bicarbonate was more than twice that in the albumin group. This was statistically significant. CONCLUSION: In normotensive infants, use of bicarbonate to correct metabolic acidosis may be more effective than use of albumin.

Acidosis↗
PubMed1999

Radiopacity of tantalum oxide nanoparticle filled resins.

OBJECTIVES: Radiopacity of composite resins allows radiographic distinction of existing restorations and recurrent caries. Current composites must be supplemented with heavy metal-containing glasses or minerals to achieve a desired radiopacity. The purpose of this study was to evaluate the radiopacity of Tantalum oxide (Ta2O5) filled resins at varying percentage loadings. METHODS: Methacrylate functionalized Ta2O5 nanoparticles (< 50 nm) in methanol-dissolved or powder forms were mixed into either glycerol dimethacrylate (GDMA) or a bisGMA, TEGDMA, bisEMA mixture (GTE). Specimens were made in a split brass mold (2 x 2 x 15 mm) and compared with an aluminum stepwedge (99.5% pure Al) and a dentin slice of the same thickness. Kodak Ultraspeed periapical X-ray film on a lead plate at a target distance of 45 cm was exposed at 70 kVp and 10 mA, for 0.5 s and processed automatically. Optical density was measured (n = 3) with an RMI Processor Control Densitometer. Radiopacity was calculated as percent relative linear attenuation coefficient (Alpha). ANOVA and Student-Newman-Keuls comparisons were used to determine significance at the 95% confidence level. RESULTS: Radiopacity increased significantly with Ta2O5 loading (p = 0.001). Ta2O5 nanoparticle filled resins enter the optimal range of diagnostic detectability (alpha = 150-250) at 50 wt.% and approach equivalence with enamel at approximately 70 wt.%. SIGNIFICANCE: The introduction of tantalum oxide nanoparticle filler has potential as a miscible component of a resin composite to provide radiopacity for microfiller-type restorative materials and to circumvent the need for hydrolysis-prone glass reinforcing fillers.

Analysis of Variance↗
PubMed1999

Promoting sun protection in children: rationale and challenges.

This article outlines the epidemiological and educational arguments for promoting sun protection during childhood and highlights factors that may facilitate or hinder achievement of this behavioral outcome. A model describing behavioral factors in the causation of skin cancer is presented. Summary results from previous behavioral studies and interventions relating to primary prevention of skin cancer are described, and recent data on the cost-effectiveness of sun protection in Australia and its implications for health insurers are discussed. This article also includes a commentary on the demonstration projects promoting skin cancer prevention among children and their caregivers featured in this special issue of Health Education and Behavior.

Adolescent↗
PubMed1993

Effects of dietary fatty-acid supplementation on fatty-acid composition and deformability of young and old erythrocytes.

The effects of cell age on erythrocyte phospholipid fatty-acid composition and deformability were examined in 20 healthy adults (11 male, 9 female) prior to and following 12 weeks of dietary supplementation with 3.5 g/day of safflower oil (high in n - 6 fatty acids) or fish oil (high in n - 3 fatty acids). In the absence of dietary supplementation, old erythrocytes demonstrated an increase in filtration time (P < 0.001), an increase in membrane phospholipid total n - 6 fatty acids (P < 0.01), and a decrease in total n - 3/total n - 6 ratio (P < 0.01) compared to young erythrocytes. Both safflower and fish oil supplementation attenuated age-related differences in membrane phospholipid total n - 6 and total n - 3 fatty acids. Fish oil supplementation also increased the proportion of n - 3 fatty acids (P < 0.01) and the n - 3/n - 6 ratio (P < 0.05) in the phospholipids of both young and old erythrocytes, and eliminated age-related differences in erythrocyte filtration time by reducing the relative filtration time of the old erythrocytes.

Adult↗
PubMed1992

Liver ultrasound findings in a low prevalence area of S. japonicum in China: comparison with history, physical examination, parasitological and serological results.

The paper describes a study carried out in a community in Dongdian township, Anhui Province, People's Republic of China. Medical history and the results of a physical examination, ultrasound investigation, parasitological and serological tests for Schistosoma japonicum infection were compared in 661 persons of 169 households. A lack of correlation between parasitological and serological indicators of infection and morbidity was observed in this area of low (6.4%) prevalence and intensity of infection. The prevalence of abnormal ultrasound findings in the liver in this population was high (56%), and was significantly higher than the prevalence of S. japonicum infection. The abnormal ultrasound findings correlated with a history of schistosomiasis, and the correlation increased significantly according to the number of times treated and the time since the last treatment, which suggested that past parenteral treatment has a role in the high rate of abnormal liver ultrasound findings. The significant correlation between the qualitative and quantitative serological results and abnormal ultrasound parenchymal patterns suggests that cross-reactivity between the etiology of the parenchymal disease and these tests is occurring. The presence of HBsAg correlated with the composite presence of ultrasound abnormalities of the liver parenchyma: increased echogenicity, periportal fibrosis and/or nodules and irregular fibrosis, whereas a normal ultrasound pattern was associated with the absence of HBV antigenemia.

Adolescent↗
PubMed1992

Attenuation of cyclosporine-induced hypertension by dietary fatty acids in the borderline hypertensive rat.

The effects of dietary (10% calories) safflower (SAF), evening primrose (EPO), and fish oil (F) as sources of linoleic acid (control), gamma-linolenic acid, and long-chain n-3 fatty acids, respectively, on cardiovascular and renal responses to chronic (5 weeks) cyclosporine administration were studied in male borderline hypertensive rats. In one experiment (n = 9/group), oral administration of CsA at 0.1 mg/kg.day significantly increased awake systolic blood pressure vs. placebo in SAF-fed rats (P less than 0.01). This increase was prevented by both EPO (P less than 0.001) and F (P less than 0.01), in the absence of group differences in body weight gain or plasma electrolyte levels. In a second experiment, CsA also increased blood pressure vs. placebo in SAF-fed rats (P less than 0.001). While this increase was prevented by EPO (P less than 0.001), F had no significant effect. Differences in group blood pressure responses were not explained by group differences in body weight gain or trough levels of blood CsA. Renal function, assessed in anesthetized rats after week 5, demonstrated a CsA-related (10 mg/kg.day) decrease in whole-kidney GFR in SAF-fed animals vs. placebo (P less than 0.05) that was prevented by EPO and attenuated by F. EPO and F also tended to reduce the CsA-induced elevation in renovascular resistance, but this difference did not reach statistical significance. These findings suggest the potential of dietary EPO and F to offset nephrotoxic effects of CsA administration, and suggest that EPO may also be useful in countering CsA-induced hypertension.

Animals↗
PubMed1992

Selective population chemotherapy among schoolchildren in Beheira governorate: the UNICEF/Arab Republic of Egypt/WHO Schistosomiasis Control Project.

Selective population chemotherapy using a single dose of praziquantel (40 mg per kg body weight), which was offered to 29,365 schoolchildren in Abu El Matameer and 40,241 in Abo Homos districts, Beheira governorate in the Nile delta, reduced the prevalence of schistosomiasis from 75.4% to 40.9% (reduction of 45.8%) and from 80.5% to 30.8% (reduction of 61.7%), respectively. Of those with only S. mansoni infection, 10.6% before treatment and 1.7% one year later had more than 800 eggs per gram of faeces. The prevalence of S. haematobium in Abu El Matameer was reduced from 35.4% to 7.4% after a single treatment. Infections with both S. mansoni and S. haematobium were reduced by more than 90% after one year. These reductions in prevalence and intensity of schistosomiasis in the face of continuing transmission and water contact augur well for the future role of chemotherapy in control programmes.

Adult↗
PubMed1990

Control of morbidity due to Schistosoma haematobium on Pemba Island: egg excretion and hematuria as indicators of infection.

The variability of Schistosoma haematobium egg excretion using a quantitative syringe filtration technique and the variability of hematuria detected visually and by reagent strips were studied in a population of 520 subjects from the village of Pujini (Pemba Island, Zanzibar, Tanzania) for 6 consecutive days. A high degree of day-to-day variability of egg excretion within subjects was found both in the whole population and in the 5-19 year age group. Subjects with 1 urinary egg count of greater than or equal to 50 eggs/10 ml urine were not similarly classified in 36-61% of the other 5 examinations and 4-16% of their other examinations were negative. Gross hematuria had a specificity of almost 100%, when related to a positive filtration on any day, and was closely related to egg counts of greater than or equal to 50 eggs/10 ml urine. The finding of a strongly positive reaction for hematuria on a given single day was closely associated with the subject having a high egg count (greater than or equal to 50 eggs/10 ml urine) on at least one of the 6 days of the study. At the primary health care level, single highly positive semiquantitative values for hematuria were a more useful diagnostic indicator than a single egg count to select patients with heavy infections for selective population chemotherapy.

Adolescent↗
PubMed1990

Metrifonate in the control of urinary schistosomiasis in Zanzibar.

Selective population chemotherapy using three doses of metrifonate (7.5 mg/kg body weight each time) at two-week intervals was assessed in an entire community in Kinyasini district in Zanzibar, United Republic of Tanzania. The objectives of the study were to (1) reduce the prevalence of heavy infections (defined as greater than or equal to 50 S. haematobium eggs per 10 ml of urine) by 75% in two years, and (2) reduce the overall prevalence of infection by 50% in two years. A total of 4113 people were examined at least once during the two-year period. In the initial survey the highest proportion of infected individuals was in the 10-14-year age group, and in all subsequent surveys in the 5-9-year age group. The age group with the highest proportion of heavily infected individuals was 5-9 years for all surveys. The overall reduction of prevalence of infection from survey 1 to survey 4 was 52.9% and the prevalence of heavy infection was reduced by 62.2%. The conversion rates (negative to positive in two consecutive surveys) were highest in the longest interval of 12 months and the rates of reversion (positive to negative in two consecutive surveys, without a history of treatment) were highest in the shortest interval of 4 months. Some statistically significant relationships were observed between the number of doses and the egg reduction rates. However, for the egg-negative rates, no statistically significant relationship was observed. In the 4-month interval a 67.6% egg-negative rate was observed among those who took at least one dose; with the 12-month interval a 48.3% egg-negative rate was observed. Thus, selective population chemotherapy with metrifonate was shown to reduce the prevalence and intensity of infection due to S. haematobium over a 24-month period.

Adolescent↗
PubMed1990

Comparison of the Teesdale glass sandwich and Kato-Katz techniques for the diagnosis of Schistosoma mansoni: a double-blind study.

In a double blind study, the Teesdale glass sandwich and Kato-Katz techniques were compared for the diagnosis of Schistosoma mansoni. From each of five stool specimens, six slide preparations were made by each method, and each slide was read independently by two readers. Examination of the differences in the number of eggs per slide by Analysis of Variance (ANOVA) showed no significant differences between methods, readers, or slides prepared from the same specimen at the 90% level of significance.

Analysis of Variance↗