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Biomedical subjects

A McDonald

Publications and source records attributed to A McDonald.

At least 37 records · Page 2Linked to original sources
PubMed2001

Mitral valve replacement with mechanical prostheses in children: improved operative risk and survival.

OBJECTIVE: The purpose of this study was to assess the early and late outcome following mitral valve replacement (MVR) with mechanical prostheses in children. PATIENTS AND METHODS: Between 1981 and 2000, 44 consecutive children (mean age 6.8+/-4.7 years, 2 months--16 years) underwent mechanical MVR in Southampton. Twenty-three children were less than 5-years-old and nine were infants. Disease aetiology was congenital in 37, rheumatic in four, infective in two and Marfan's syndrome in one. Mitral regurgitation was present in 36 and mitral stenosis in eight. Concomitant procedures were performed in 13, including aortic valve replacement (AVR) in seven. Follow-up was complete (mean 6.4+/-4.8 years, 1 month--18.1 years). RESULTS: The overall operative mortality was 14% (six patients). Before and after 1990 operative mortality was 31 vs 3.6% (P=0.02). From 1990, operative mortality for infants was zero out of six, for children less than 5-years-old was one out of 16 (one death after emergency AVR and MVR) and for older children it was 0/12. Seven children experienced valve or anticoagulation treatment-related events and eight had a mitral valve re-operation. Ten-year freedom from thromboembolism, prosthetic valve infection, bleeding, paravalvular leak and a mitral valve re-operation was 92.8+/-5.2, 97.3+/-2.7, 97.7+/-2.3, 97.2+/-2.7 and 75+/-9.7%, respectively. Overall 10-year survival was 78+/-7% (four late deaths); for children under vs over 5 years it was 61+/-11 vs 95.2+/-4.6% (P=0.02), for atrio-ventricular septal defect (AVSD) vs other pathology 55+/-15 vs 89+/-6.1% (P=0.05) and for those operated before 1990 vs after 1990 it was 63+/-8.1 vs 86+/-8.2% (P=0.04). CONCLUSIONS: Mechanical MVR, in the current era, carries a low operative risk across the spectrum of paediatric age. Late survival is better for older children and those having no-AVSD pathology but it has improved substantially during the 1990s irrespective of age and disease aetiology.

Age Factors↗
PubMed2001

Time trends in HIV incidence among homosexually active men seen at sexual health clinics in Australia, 1993-1999.

BACKGROUND: Increases in sexual risk behaviour have recently been reported among homosexually active men in Australia and in other industrialised countries, potentially facilitating an increase in HIV incidence. OBJECTIVE: To monitor HIV incidence among homosexually active men seen through a network of sexual health clinics in Australia. STUDY DESIGN: Selected metropolitan public sexual health clinics provided counts of the number of people seen at the clinics during a calendar year, the number voluntarily tested for HIV antibody and the number newly diagnosed with HIV infection, broken down by sex, age group, HIV exposure category and HIV antibody testing history. HIV incidence was estimated among homosexually active men with a history of a negative test in the 12 months prior to last being seen in a calendar year. RESULTS: Of 23924 men seen at the clinics in 1993-1999 with a reported history of male homosexual contact, 7440 (31.1%) had a negative test in the 12 months prior to last being seen in a calendar year. The percentage of men with a recent negative test declined significantly over time, from more than 33% in 1994-1996 to 29% in 1999 (P=0.003), and with increasing age, from 34.3% among men aged 25-29 years to 27.4% among men aged 40 years or older (P<0.0005). A total of 5346 (71.9%) men were retested for HIV antibody within 12 months of the last negative test. The percentage of men retested declined significantly over time, from 77.8% in 1994 to 67.2% in 1999 (P=0.021) but did not change by age group (P=0.132). Overall, 56 men were newly diagnosed with HIV infection. Estimated HIV incidence was 2.1% in 1993-1999; incidence did not change significantly by year (P=0.498) or age group (P=0.757). CONCLUSION: HIV incidence has remained stable among homosexually active men seen through a network of sexual health clinics in Australia.

Adolescent↗
PubMed2001

The portrayal of ECT in American movies.

OBJECTIVE: To describe the portrayal of electroconvulsive therapy (ECT) in American films. This has not been systematically studied previously, despite some notorious ECT scenes in the history of American cinema and the impact of films on audiences. METHOD: All movies depicting or making reference to ECT were identified from a number of sources. Available movies were viewed on at least two occasions. RESULTS: 22 films, beginning with The Snake Pit and ending with Requiem for a Dream, portraying or making reference to ECT were made between 1948 and 2000. 20 (91%) of these movies were obtained and viewed. CONCLUSION: Having commenced its movie career as a severe but helpful remedy for personal distress, ECT on film has become a progressively more negative and cruel treatment, leaving the impression of a brutal, harmful, and abusive maneuver with no therapeutic benefit.

Electroconvulsive Therapy↗
PubMed2001

Preparation guidelines for full and partial coverage ceramic restorations.

Aesthetic awareness of dental patients has produced a growing demand for posterior tooth-coloured restorations. This has led to the development of posterior composite resins and, more recently, posterior all-ceramic restorations. In the last decade, modern technological advances have allowed the production of stronger ceramics and better luting techniques, which have led to the use of all-ceramic restorations in posterior sites. The preparation guidelines for posterior ceramic restorations outlined in this paper emphasize rounded internal line angles and a chamfer or rounded shoulder finish-line.

Bicuspid↗
PubMed2001

Advances in operative dentistry and fixed prosthodontics.

The rapid developments in biomaterials has led not only to improved materials but also to the development of clinical techniques made possible by these advances. Adhesive dentistry remains one of the fastest changing fields and this will most likely continue well into the next decade. Patients' aesthetic awareness and, to some extent, concern about amalgam has produced a growing demand for posterior tooth-coloured restorations. Originally this was met by ceramo-metal crowns and subsequently by the development of posterior composite resins. Recent development of stronger ceramics and better luting have now made all-ceramic restorations possible in posterior sites. Several new techniques for cavity preparation are emerging as alternatives to the conventional handpiece while the quest for amalgam alternatives continues. As with all recent developments there are, by definition, few long-term clinical data yet available to allow a comprehensive evaluation of the relevant materials and techniques. This paper is a summary of the most significant recent advances in fixed prosthodontics and operative dentistry.

Dental Amalgam↗
PubMed2001

Patterns of trauma injuries in rural versus urban Jamaica.

Trauma admissions to St Ann's Bay Hospital in rural Jamaica and The University Hospital of the West Indies (UHWI) in the capital city of Kingston are compared. Trauma accounted for 19% and 22% of surgical admissions to UHWI and the St Ann's Bay Hospital, respectively. Sixty-three per cent of trauma cases admitted to the St Ann's Bay Hospital and 56% to the UHWI were due to unintentional injuries (95% CI, -0.05, 0.19). The main cause of unintentional injuries at both hospitals was motor vehicle accidents, accounting for 43% and 37% at UHWI and St Ann's Bay Hospital respectively (95% CI, -0.04, 0.17). The prevalence of falls was significantly higher in St Ann's Bay Hospital compared with UHWI, 41% and 26% respectively (95% CI, 0.10, 0.21). Intentional injuries accounted for 37% of cases in St Ann's Bay Hospital and 44% at UHWI (95% CI, -0.20, 0.04). The prevalence of firearm injuries was significantly higher at the UHWI than in St Ann's Bay Hospital, 55% and 18% respectively (95% CI, -0.15, -0.05). There was no significant difference in age and injury severity scores in the two hospitals but patients remained in hospital significantly longer at UHWI.

Adult↗
PubMed2001

Management of hepatic cysts by percutaneous drainage and instillation of tetracycline hydrochloride.

This paper reports two cases of benign hepatic cysts successfully treated by the instillation of tetracycline hydrochloride. The patients presented with solitary large symptomatic hepatic cysts and underwent ultrasound guided needle aspiration followed by the instillation of tetracycline hydrochloride. The cyst size diminished without complication and the patients have remained symptom free. We review the treatment of this uncommon entity and propose that injection of tetracycline hydrochloride is an effective nonoperative treatment of symptomatic solitary hepatic cysts.

Adolescent↗
PubMed2001

Treatment planning for success: wise choices for maxillary single-tooth implants.

The purpose of this article is to demonstrate to general practitioners who have no experience with dental implant treatment the esthetic limitations of such treatment. The criteria for wise case selection will be described so that esthetic excellence can be predictably achieved in general practice. A checklist of criteria will be provided as a treatment-planning tool to determine if a patient is likely to have an esthetically successful outcome.

Alveolar Process↗
PubMed2000

Aortic valve replacement in children: are mechanical prostheses a good option?

OBJECTIVE: The choice of the most appropriate substitute in children with irreparable aortic valve lesions remains controversial. The aim of this study was to assess early and late outcomes following aortic valve replacement (AVR) with mechanical prostheses in children. PATIENTS: Fifty-six patients (42 male, 14 female, mean age 11.2, range 1-16 years) undergoing AVR with mechanical prostheses between October 1972 and January 1999 were evaluated. Thirty-six patients (64.2%) underwent previous cardiac surgery. Disease aetiology was congenital in 47 patients (congenital aortic stenosis in 33, and other congenital abnormalities in 14) (83.9%), infective in four (7. 1%), rheumatic in two (3.4%), and three (5.3%) had connective tissue disorders. Haemodynamic indication for AVR was aortic regurgitation (AR) in 24 (42.8%), aortic stenosis (AS) in 22 (39.2%) and mixed disease in ten (17.8%). Twenty-eight patients (50.0%) were in New York Heart Association (NYHA) class III-IV before surgery. Concomitant procedures were performed in 31 patients (55.3%), including aortic root enlargement in 28 (50%). The mean size of implanted valves was 22.4 mm (range 17-27 mm). All patients received long-term anticoagulation treatment with sodium warfarin, aiming to maintain an international normalized ratio (INR) between 2.5-3.0. The mean follow-up was 7.3 years (range 0-26, total 405 patient-years). RESULTS: Operative mortality was 5.3% (three patients). Three patients developed complete heart block requiring pacing, two of them permanently. Late events included valve thrombosis (one), transient stroke (one), paravalvular leak of a mitral prosthesis (one), aneurysm of sinus of Valsalva (one) and pannus ingrowth (one). There was no major haemorrhagic event. Five patients required re-operation (8.9%), but none due to outgrowth of the valve. Regarding actuarial freedom from thrombo-embolism, any valve-related event and re-operation at 20 years was 93, 86.6 and 86. 4%. There were three late deaths. Actuarial survival, including operative mortality, at 10 and 20 years was 91 and 84.9%. The actuarial survival for the group of the patients with congenital AS (n=33) at 10 and 20 years was 93.5%, whereas for the children with other congenital heart problems (n=14) this was 85.7 and 64.3% (P=0. 09). At the latest clinical evaluation, 44 children were in NYHA class I and six were in class II. The mean gradient across the aortic prosthetic valve on echocardiography was 17.9 mmHg (range 0-47 mmHg). CONCLUSIONS: Mechanical AVR, with enlargement of the aortic root if necessary, remains an excellent treatment option in children. It is associated with acceptable operative mortality, low incidence of late events and re-operation, and provides good long-term survival. It clearly represents a good alternative to available biological substitutes, including the pulmonary autograft (Ross procedure).

Actuarial Analysis↗
PubMed2000

Voiding cystourethrograms and urinary tract infections: how long to wait?

OBJECTIVES: Many authorities recommend an interval of at least 3 to 6 weeks after a urinary tract infection (UTI) before performing a voiding cystourethrogram (VCUG). However, such an interval may reduce the likelihood of completing the procedure. This study was performed to investigate whether the length of the interval between a UTI and the performance of the VCUG influences the presence or severity of reflux, and whether it influences the likelihood of actually having the study performed. DESIGN: We reviewed 352 admissions of children under 10 years old whose discharge diagnoses indicated UTIs. These admissions occurred over a 27-month period between October 1994 and December 1996 at the Children's Hospital of Austin, Texas. We identified 213 patients with confirmed UTIs and no other previously defined urinary tract pathology. These patients were divided into 2 groups according to whether they had a VCUG scheduled to be performed either within 1 week after the diagnosis of a UTI (the early group), or later than 1 week after the diagnosis (the late group). We compared the presence and severity of reflux in the 2 groups as well as the proportion of scheduled VCUGs that were actually performed. RESULTS: Reflux was present in 19% of the patients studied within 1 week after UTI (95% confidence interval [CI]: 12.9-26.4) and in 18% of those studied after 1 week (95% CI: 6. 7-34.5). This difference was not statistically significant (chi(2) =. 034; DF = 1). However there was a substantial difference between the 2 groups with regard to the number of scheduled VCUGs actually performed. Whereas 100% of the scheduled VCUGs in the early group were performed, only 48% (95% CI: 35.9-60.1) of those scheduled in the late group were performed. This difference is statistically significant (chi(2) = 89.6; DF = 1). CONCLUSIONS: In the hospitalized children who underwent VCUGs within a week after diagnosis of UTI, the presence of reflux is not significantly different from those studied later. Furthermore, late scheduling of VCUGs resulted in failure to perform the procedure in more than half of the patients. Some of the patients who were not evaluated would be expected to have vesicoureteral reflux and thus be at risk for chronic renal disease. Therefore, the traditional recommendation to perform the VCUG at 3 to 6 weeks after the diagnosis of UTI should be reconsidered, especially for hospitalized children.

Child↗
PubMed2000

Chronic relapsing pancreatitis in a child. Use of the Puestow procedure to achieve ductal drainage.

A case of chronic relapsing pancreatitis presenting in an 8-year-old African Jamaican girl is outlined. Aggressive supportive management failed to control pain and vomiting. The Puestow Procedure effectively procedure aborted these symptoms. The use of the Puestow procedure should not be inordinately delayed in chronic relapsing pancreatitis if symptoms persist, since it may not only control pain but also halt declining pancreatic function.

Child↗
PubMed1999

The protein kinase C inhibitor CGP41251 suppresses cytokine release and extracellular signal-regulated kinase 2 expression in cancer patients.

Components of cell signaling pathways provide important targets for anticancer drugs. Protein kinase C (PKC) is a serine/threonine-specific kinase that regulates cell growth and differentiation. It is also implicated in tumor promotion. The staurosporine analogue CGP41251 is a PKC inhibitor, and it is currently in a Phase I clinical trial for treatment of advanced cancer. However, it is difficult to define its biological activity. We have used two approaches to measure the in vivo biological response to CGP41251: (a) sequential whole blood samples were taken from 27 patients before and during treatment and incubated with mitogen (PHA), and cytokine [tumor necrosis factor (TNF)-alpha and interleukin (IL)-6] release was measured ex vivo; and (b) peripheral blood lymphocytes were isolated from seven of these patients, and the levels of extracellular signal-regulated kinase 2 were measured by Western blotting. Response to PHA was significantly lowered during treatment (P < 0.001 for TNF-alpha production; P < 0.03 for IL-6). This was most evident at 7 and 28 days after the start of treatment in patients receiving higher doses (150-300 mg/day; P = 0.002 and P = 0.02, respectively, for TNF-alpha and P = 0.001 and P = 0.003, respectively, for IL-6 release). Whole blood cytokine production returned to pretreatment levels after drug administration ceased. The levels of extracellular signal-regulated kinase 2 were reduced by 50-97% during treatment in all seven patients tested. These results show for the first time that a PKC inhibitor can block in vivo signaling pathways in cancer patients. The assays we describe complement toxicity studies in selecting relevant doses for Phase II trial of novel agents, particularly when biological activity occurs at doses below those that cause obvious side effects.

Adult↗
PubMed1999

Neonatal examination and screening trial (NEST): a randomised, controlled, switchback trial of alternative policies for low risk infants.

OBJECTIVE: To evaluate the effectiveness of one rather than two hospital neonatal examinations in detection of abnormalities. DESIGN: Randomised controlled switchback trial. SETTING: Postnatal wards in a teaching hospital in north east Scotland. PARTICIPANTS: All infants delivered at the hospital between March 1993 and February 1995. INTERVENTION: A policy of one neonatal screening examination compared with a policy of two. MAIN OUTCOME MEASURES: Congenital conditions diagnosed in hospital; results of community health assessments at 8 weeks and 8 months; outpatient referrals; inpatient admissions; use of general practioner services; focused analysis of outcomes for suspected hip and heart abnormalities. RESULTS: 4835 babies were allocated to receive one screening examination (one screen policy) and 4877 to receive two (two screen policy). More congenital conditions were suspected at discharge among babies examined twice (9.9 v 8.3 diagnoses per 100 babies; 95% confidence interval for difference 0.3 to 2.7). There was no overall significant difference between the groups in use of community, outpatient, or inpatient resources or in health care received. Although more babies who were examined twice attended orthopaedic outpatient clinics (340 (7%) v 289 (6%)), particularly for suspected congenital dislocation of the hip (176 (3.6/100 babies) v 137 (2.8/100 babies); difference -0.8; -1.5 to 0.1), there was no significant difference in the number of babies who required active management (12 (0.2%) v 15 (0.3%)). CONCLUSIONS: Despite more suspected abnormalities, there was no evidence of net health gain from a policy of two hospital neonatal examinations. Adoption of a single examination policy would save resources both during the postnatal hospital stay and through fewer outpatient consultations.

Ambulatory Care↗
PubMed1999

AIDS diagnoses at higher CD4 counts in Australia following the introduction of highly active antiretroviral treatment.

OBJECTIVES: To assess whether AIDS cases in Australia have been diagnosed at higher CD4 counts since the widespread availability of highly active antiretroviral treatment (HAART) in mid-1996. METHODS: Data on the CD4 count at AIDS diagnosis for AIDS cases diagnosed between 1 January 1992 and 31 December 1997, and reported to the National AIDS Registry in Australia by 31 March 1998, were analysed. The median CD4 count at AIDS diagnosis, and the proportions of AIDS diagnoses with a CD4 count above 100 cells/microl, and above 200 cells/microl, were calculated by the year of diagnosis, both for all AIDS-defining illnesses, and for each illness separately. Analyses were also stratified by the time interval between HIV and AIDS diagnoses (less than or equal to, or more than, 3 months) because people diagnosed with HIV close to the diagnosis of AIDS would generally not have received any antiretroviral treatment before the diagnosis of AIDS, and so no trends in CD4 counts at the diagnosis of AIDS would be expected in this group. RESULTS: There was an increase in CD4 count at AIDS diagnosis in 1996 and 1997, although this increase was only apparent for AIDS-defining illnesses other than Pneumocystis carinii pneumonia (PCP), and was limited to AIDS cases diagnosed with HIV more than 3 months before AIDS. In cases of AIDS other than PCP, and diagnosed with HIV more than 3 months before AIDS, the median CD4 count increased from 50 cells/microl in 1995 to 80 cells/microl in 1996 and 134 cells/microl in 1997. CONCLUSIONS: There has been an increase in the CD4 count at AIDS diagnosis for most AIDS-defining illnesses in Australia coincident with the widespread availability of HAART.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Elemental composition of human milk from mothers of premature and full-term infants during the first 3 months of lactation.

To examine longitudinal and gestational effects of mineral content in human milk, we analyzed human milk from lactating mothers of premature (PRT, n = 24, < 2000 g birth weight, < 37 wk gestation) and full-term (FT, n = 19, > 2500 g, 39-41 wk gestation), living in Newfoundland, Canada. Samples were collected once a week for 8 wk with one final sample collected at 3 mo. Milk samples collected in acid-washed containers were wet ashed with concentrated HNO3, and barium, cadmium, calcium, cesium, cobalt, copper, cerium, lanthanum, magnesium, manganese, molybdenum, nickel, lead, rubidium, tin, strontium, and zinc were measured using inductively coupled plasma-mass spectrometry. Data were analyzed using standard multiple-regression procedures with correlated data analyses to take account of the relationship between successive weeks. Results indicated lower Ca and Pb in PRT milk. Calcium was the only nutritionally significant element to differ between groups. Molybdenum in both PRT and FT milk showed a definite decrease with time, suggesting that the Mo content in milk is homeostatically regulated. However, Ce, La, Ba, and Sn did not display any pattern indicative of biological regulation and potential human requirement.

Female↗