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Biomedical subjects

R McLean

Publications and source records attributed to R McLean.

At least 19 recordsLinked to original sources

Continuing professional development for rural physicians: an oxymoron or just non-existent?

There is geographic maldistribution of physicians across Australia and their professional isolation, particularly in relation to continuing professional development, is a definite problem. It tends to be worse in smaller centres where there is no critical mass that allows for peer support. Although some academic research has been carried out concerning the needs of rural GP, none has targetted rural specialists. Several activities, including the Commonwealth-funded Support Scheme for Rural Specialists, have been well received and other initiatives, including the rural clinical schools and university departments of rural health, are beginning to provide an infrastructure that will help overcome the professional isolation through the use of innovative technologies such as interactive videoconferencing. This is being used to deliver RACP initiatives such as the basic physician trainee lecture series and the potential for vertical integration of training in rural settings which offer some promise to address the rural workforce shortage in the years to come.

Australia↗

Pathogen reduction of buffy coat platelet concentrates using riboflavin and light: comparisons with pathogen-reduction technology-treated apheresis platelet products.

BACKGROUND AND OBJECTIVES: A pathogen-reduction technology (PRT) system using riboflavin and light has been developed for the treatment of platelet concentrates (PC) obtained by either buffy coat preparation (BCPC) or apheresis procedures (APPC). The aim of this study was to evaluate the effects of the treatment process on in vitro cell quality and on riboflavin conversion in PC. MATERIALS AND METHODS: BCPC were prepared with the Compomat G4 from whole blood which had been stored overnight after collection. APPC were obtained using the TRIMA apheresis procedure. Both PC products had been stored for 18-24 h prior to PRT treatment. BCPC and APPC were treated with PRT on day 2 and day 1 of shelf-life, respectively. The treated PCs were then maintained for an additional 5 days after the PRT treatment. A panel of cell quality assays and high-performance liquid chromatography (HPLC) analysis were performed. RESULTS: Cell counts and plasma lactate dehydrogenase (LDH) levels during storage indicated that PRT did not induce significant cell lysis. Acceleration of a decrease in glucose and an increase in lactate was observed for treated PCs, but no significant differences were observed between treated BCPC and APPC. The pH of treated samples remained above 7.0, although was lower than that of the control. Platelet morphology of BCPC and APPC was well preserved. P-selectin expression indicated significant platelet activation when compared with control PC (BCPC on day 6: 39% vs. 12%; APPC on day 5: 35% vs. 18%). Both P-selectin expression and microparticle formation were not significantly different between treated BCPC and APPC during storage. The JC-1 assay also displayed no loss of mitochondria integrity during the storage of treated products. Approximately 20% of riboflavin converted into photoproducts, including lumichrome. CONCLUSIONS: PRT treatment had an effect on the development of the normal platelet storage lesion at a level which seems tolerable for clinical usage.

Blood Component Removal↗

Serum uric acid levels in optic neuritis.

Uric acid, an antioxidant, is reduced in multiple sclerosis (MS). Patients with gout have a reduced incidence of MS. Optic neuritis (ON), often the first manifestation of MS, is not known to be associated with reduced uric acid. Patients with recent onset of ON were investigated to determine whether uric acid levels were reduced at presentation. Twenty-one patients with ON were included, 17 females and 4 males. The mean (SD) serum uric acid in the ON female group was 184.4 ( +/-55.1) micromol/L (range, 116-309 micromol/L), whilst in the control group it was 235.2 (+/- 50.2) micromol/L (range, 172-381 micromol/L). The difference was statistically significant (chi2 = 8.93, P = 0.003). In the small male cohort, mean (SD) serum uric acid was 305 (+/- 52.1) micromol/L, whilst in the control group it was 328 (+/- 80.4) micromol/L. These differences were not statistically significant. Reduced antioxidant reserve is possibly an early pathogenic mechanism in inflammatory demyelination, and raises the possibility that low uric acid levels could be an indicator of disease activity. Since optic neuropathies of other causes were not investigated, future research needs to determine whether low uric acid represents a unique feature of optic neuritis or is seen in other optic neuropathies.

Adult↗

Development and optimisation of a generic micellar electrokinetic capillary chromatography method to support analysis of a wide range of pharmaceuticals and excipients.

A micellar electrokinetic capillary chromatography (MECC) method has been developed and validated to allow the analysis of a wide range of water soluble and insoluble acidic, basic and neutral drugs and excipients. An electronic database has been established to demonstrate the wide applicability of the method. The method has been validated and is now in routine use. In particular, acceptable injection precision is obtained through use of internal standards. Optimal sensitivity was obtained by using low UV wavelength detection. The method allows a number of cost and time saving benefits.

Chromatography, Micellar Electrokinetic Capillary↗

The area of complete scotopic spatial summation enlarges with age.

The maximal area of complete scotopic spatial summation (Ricco's area) was determined for 50 subjects ranging in age from 19 to 87 yr. Increment thresholds were measured for 10-ms, 520-nm circular test lights of varying diameters that were superimposed and concentric with a 10 degrees, 640-nm circular background. The test lights were imaged in Maxwellian view along the horizontal meridian, 6 degrees nasal from a foveal fixation point. The results demonstrate a statistically significant enlargement of Ricco's area with age. The average angular subtenses of Ricco's areas for the ten youngest (mean = 26 yr) and ten oldest (mean = 75 yr) observers were approximately 48 and 69 arc min, respectively. Model simulations based on a series of optical transfer functions of the eye and varying degrees of intraocular light scatter for younger and older observers show that preneural factors cannot account for these results. Therefore changes in neural mechanisms must be invoked to explain the enlargement in the size of Ricco's area under scotopic conditions.

Adult↗

Colon transit scintigraphy using oral indium-111-labeled DTPA. Can scan pattern predict final diagnosis?

Colon transit scintigraphy (CTS) was performed in 100 consecutive patients with idiopathic constipation using oral indium-111-labeled DTPA. Criteria were defined to allow classification of studies as normal, slow transit constipation (STC), or obstructed defecation (OD). Results were compared with final clinical diagnosis in 100 and findings of defecating proctography in 70. Of those with a scintigraphic diagnosis of STC, this was also the final diagnosis in 75% (33 of 44), and the scintigraphic diagnosis of OD was confirmed in 61% (17 of 28). Of 28 normal or equivocal scans, the final diagnosis was STC in only two (4%) but OD in 10 (21%). Fifty-four percent of patients with STC and 71% with OD had abnormal proctograms. The correlation between CTS and proctography was mediocre, occurring in 54% of patients. CTS has a valuable role in the diagnostic work-up of patients with idiopathic constipation.

Aged↗

Re-evaluating the need for hospitalization following synovectomy using Yttrium-90 silicate.

In 51 patients treated with Yttrium-90 (Y-90) synovectomy for rheumatoid (inflammatory) arthritis (IA) and OA of the knee we found that decreased retained knee activity (RKA) and increased extra-articular activity in lymph nodes and liver are more likely to be found in IA than OA and following bilateral knee injections. Joint inflammation, as assessed by radionuclide blood pool scan but not by SF white cell count, correlates with decreased RKA and increased activity in lymph nodes. Intra-articular steroid had no significant effect on retention or extra-articular uptake. Strict hospital immobilization improves RKA of Y-90 in IA but not in OA. Y-90 synovectomy in OA shows good RKA and low extra-articular uptake. We recommend strict immobilization following Y-90 synovectomy, particularly in IA patients and/or those with high joint blood flow.

Adult↗

Hemodynamic profiles of prostaglandin E1, isoproterenol, prostacyclin, and nifedipine in experimental porcine pulmonary hypertension.

BACKGROUND AND METHODS: We compared the hemodynamic effects of four vasodilators in experimental embolic pulmonary hypertension in a randomized controlled trial, using nine pigs weighing 16 to 23 kg. After anesthesia induction and cannulation with arterial, central venous, and thermodilution output pulmonary artery catheters, animals were repetitively embolized with glass beads (60 to 160 mu) in order to establish pulmonary hypertension (pulmonary artery pressure [PAP] doubled from baseline). Prostaglandin E1 (PGE1), isoproterenol, prostacyclin (PGI2), and nifedipine were compared at doses producing equivalent reduction in systemic BP. RESULTS: Only PGE1 and PGI2 decreased both PAP and pulmonary vascular resistance (PVR). PGE1 decreased PAP from 39 +/- 1 to 33 +/- 1 mm Hg; prostacyclin decreased PAP from 38 +/- 1 to 31 +/- 1 mm Hg and produced the largest increase in cardiac output (Qt). Isoproterenol did not change PAP, markedly increased heart rate (162 +/- 8 to 216 +/- 11 beats/min), and resulted in significant arrhythmias. Nifedipine increased PVR from 1044 +/- 113 to 1125 +/- 100 dyne.sec.cm-5 and decreased Qt. CONCLUSIONS: Vasodilators demonstrate unique hemodynamic drug profiles. Isoproterenol infusion is characterized by tachycardia and arrhythmias. Both PGE1 and PGI2 effectively decrease PAP and PVR. Nifedipine depressed Qt significantly in this glass-bead embolization model of acute pulmonary hypertension.

Alprostadil↗

Evaluation of the Quantitative Buffy Coat (QBC) method to detect malaria-infected red blood cells.

The conventional thin blood film method of detecting malaria is a long and tedious procedure, requiring significant technical expertise. In this study, we compared the Quantitative Buffy Coat (QBC) capillary tube method, which requires only minimal technical training, to the thin blood film method, and found it to be not only more rapid but also more sensitive than the thin blood film method in the detection of parasitized red blood cells. We do not suggest that the QBC capillary method can replace the conventional thin blood film method for the detection of malaria since it does not identify or quantitate the parasite species, only that it would serve as a valuable screening test.

Animals↗

Role of bone scintigraphy in the early diagnosis of discitis.

Nine cases of recorded discitis are presented, in which scintigraphy played an important part in the diagnosis. The patients (five men (aged 21-75 years) and four women (aged 40-73 years)) had a history of back pain varying in duration from two days to three months. Final diagnosis was confirmed microbiologically (seven patients) or radiographically (two patients). Bone scintigraphy was a valuable diagnostic procedure for discitis with earlier detection than plain radiography in three patients and similar initial detection to that of third generation computed tomography. Single photon emission computed tomographic imaging increased diagnostic confidence by indicating the involvement of the adjacent vertebral bodies rather than of the pedicles or spinous processes.

Adult↗

Pylorus-preserving pancreatectomy: functional results.

The pylorus-preserving technique is reported as improving the functional results of pancreatectomy but it is complicated in the early postoperative period by delayed recovery of gastric function in a proportion of patients. We have examined early and late gastrointestinal function in a prospective study of 16 patients having this procedure. The late results appear better than reported results for conventional Whipple resection and the delay in early recovery does not appear to have any late sequelae, provided that it does not require gastric bypass for relief.

Adult↗

Thyroid dysgenesis in monozygotic twins: variants identified by scintigraphy.

The unusual occurrence of neonatal hypothyroidism in monozygotic twins is reported. Scintigraphy demonstrated that permanent hypothyroidism in one resulted from an ectopic suprahyoid thyroid, while in the other, the transient hypothyroid state was associated with thyroid hemiagenesis. These findings suggest that the anomalies represent variants of the same developmental aberration.

Congenital Hypothyroidism↗