Fractionated aliphatic alcohols as synthetic precursors of ultra long-chain monoacylglycerols for cosmetic applications

BACKGROUND

Xerosis is an abnormally dry and flaky skin condition that is associated with a change in the packing behaviour of the lipid matrix in the stratum corneum (SC), the outermost layer of the skin. This skin condition can lead to an increase in transepidermal water loss (TEWL). As ultralong-chain fatty acids have a positive effect on maintaining the packing behaviour of the SC lipid matrix, a moisturizer which contains glycerides of ultralong-chain fatty acids could act as a semi-occlusive layer on the surface of the skin. This will lower the rate of water evaporation through the epidermis and consequently help prevent or improve skin xerosis.

OBJECTIVE

To identify a novel source of ultralong-chain lipids and develop monoacylglycerols with mixed fatty acyl chain lengths that have occlusive properties superior to petrolatum.

METHODS

Initially, Performacol 425, a mixture of very long-chain fatty alcohols, was fractionated using short path distillation to yield a fraction enriched with C22:0-C26:0 fatty alcohols. The fatty alcohol fraction was then oxidized using Jones reagent, and the resulting fatty acids were esterified with glycerol to yield the corresponding monoglycerides using Novozym 435. These were then evaluated using Fourier transform infrared spectroscopy, differential scanning calorimetry and water vapour transmission rate measurements.

RESULTS

The monoacylglycerols enriched with C22:0-C26:0 displayed a melting point of 80°C and orthorhombic packing; packing behaviour mainly present in healthy SC. In addition, a phospholipid-structured emulsion containing 3% of the monoglycerides displayed occlusive properties superior to the vehicle containing 3% petrolatum jelly.

CONCLUSIONS

Performacol 425 can be a potential source of fatty alcohols to synthesize monoacylglycerols that can improve the occlusive behaviour of phospholipid-structured emulsions.

Construct validation of judgement-based assessments of medical trainees' competency in the workplace using a "Kanesian" approach to validation

BACKGROUND

Evaluations of clinical assessments that use judgement-based methods have frequently shown them to have sub-optimal reliability and internal validity evidence for their interpretation and intended use. The aim of this study was to enhance that validity evidence by an evaluation of the internal validity and reliability of competency constructs from supervisors' end-of-term summative assessments for prevocational medical trainees.

METHODS

The populations were medical trainees preparing for full registration as a medical practitioner (74) and supervisors who undertook ≥2 end-of-term summative assessments (n = 349) from a single institution. Confirmatory Factor Analysis was used to evaluate assessment internal construct validity. The hypothesised competency construct model to be tested, identified by exploratory factor analysis, had a theoretical basis established in workplace-psychology literature. Comparisons were made with competing models of potential competency constructs including the competency construct model of the original assessment. The optimal model for the competency constructs was identified using model fit and measurement invariance analysis. Construct homogeneity was assessed by Cronbach's α. Reliability measures were variance components of individual competency items and the identified competency constructs, and the number of assessments needed to achieve adequate reliability of R > 0.80.

RESULTS

The hypothesised competency constructs of "general professional job performance", "clinical skills" and "professional abilities" provides a good model-fit to the data, and a better fit than all alternative models. Model fit indices were χ2/df = 2.8; RMSEA = 0.073 (CI 0.057-0.088); CFI = 0.93; TLI = 0.95; SRMR = 0.039; WRMR = 0.93; AIC = 3879; and BIC = 4018). The optimal model had adequate measurement invariance with nested analysis of important population subgroups supporting the presence of full metric invariance. Reliability estimates for the competency construct "general professional job performance" indicated a resource efficient and reliable assessment for such a construct (6 assessments for an R > 0.80). Item homogeneity was good (Cronbach's alpha = 0.899). Other competency constructs are resource intensive requiring ≥11 assessments for a reliable assessment score.

CONCLUSION

Internal validity and reliability of clinical competence assessments using judgement-based methods are acceptable when actual competency constructs used by assessors are adequately identified. Validation for interpretation and use of supervisors' assessment in local training schemes is feasible using standard methods for gathering validity evidence.

Synchronous large tumoral pseudoangiomatous stromal hyperplasia (PASH) in the breast and axilla with subsequent carcinoma in the contralateral breast: routine and strain imaging with histopathological correlation

Pseudoangiomatous stromal hyperplasia (PASH) is a benign breast disorder with the tumoral variety being extremely rare. We report a rare case of synchronous, massive axillary and breast tumoral PASH in a 55-year-old post-menopausal woman. Mammography, ultrasonography and sonoelastography features are illustrated with histopathological correlation. A high-grade invasive ductal carcinoma was detected in the contralateral breast on annual follow-up imaging. Radiologists need to be familiar with the imaging appearances of PASH and be aware of its association with subsequent cancer risk. To the best of our knowledge, the present case of synchronous tumoral PASH in the breast and axillary tissue is the second reported case till now.

Management of primary and metastatic spinal tumors

ìTumors of the spine, though rare, may significantly impact quality of life. The management depends not only on clinical presentation, but also on histology, stage and grade of the tumor. Primary benign tumors usually are a focal problem, however, may be focally aggressive. Primary malignant tumors are always considered aggressive and are managed in a multidisciplinary fashion. Surgical treatment often requires aggressive en bloc resection to maximize potential for cure. Metastatic tumors of the spine may cause a significant impact on the quality of life. In select cases with spine instability, pain and neurologic deficit surgical management is indicated.

A critical evaluation of the validity and the reliability of global competency constructs for supervisor assessment of junior medical trainees

Supervisor assessments are critical for both formative and summative assessment in the workplace. Supervisor ratings remain an important source of such assessment in many educational jurisdictions even though there is ambiguity about their validity and reliability. The aims of this evaluation is to explore the: (1) construct validity of ward-based supervisor competency assessments; (2) reliability of supervisors for observing any overarching domain constructs identified (factors); (3) stability of factors across subgroups of contexts, supervisors and trainees; and (4) position of the observations compared to the established literature. Evaluated assessments were all those used to judge intern (trainee) suitability to become an unconditionally registered medical practitioner in the Australian Capital Territory, Australia in 2007-2008. Initial construct identification is by traditional exploratory factor analysis (EFA) using Principal component analysis with Varimax rotation. Factor stability is explored by EFA of subgroups by different contexts such as hospital type, and different types of supervisors and trainees. The unit of analysis is each assessment, and includes all available assessments without aggregation of any scores to obtain the factors. Reliability of identified constructs is by variance components analysis of the summed trainee scores for each factor and the number of assessments needed to provide an acceptably reliable assessment using the construct, the reliability unit of analysis being the score for each factor for every assessment. For the 374 assessments from 74 trainees and 73 supervisors, the EFA resulted in 3 factors identified from the scree plot, accounting for only 68 % of the variance with factor 1 having features of a "general professional job performance" competency (eigenvalue 7.630; variance 54.5 %); factor 2 "clinical skills" (eigenvalue 1.036; variance 7.4 %); and factor 3 "professional and personal" competency (eigenvalue 0.867; variance 6.2 %). The percent trainee score variance for the summed competency item scores for factors 1, 2 and 3 were 40.4, 27.4 and 22.9 % respectively. The number of assessments needed to give a reliability coefficient of 0.80 was 6, 11 and 13 respectively. The factor structure remained stable for subgroups of female trainees, Australian graduate trainees, the central hospital, surgeons, staff specialist, visiting medical officers and the separation into single years. Physicians as supervisors, male trainees, and male supervisors all had a different grouping of items within 3 factors which all had competency items that collapsed into the predefined "face value" constructs of competence. These observations add new insights compared to the established literature. For the setting, most supervisors appear to be assessing a dominant construct domain which is similar to a general professional job performance competency. This global construct consists of individual competency items that supervisors spontaneously align and has acceptable assessment reliability. However, factor structure instability between different populations of supervisors and trainees means that subpopulations of trainees may be assessed differently and that some subpopulations of supervisors are assessing the same trainees with different constructs than other supervisors. The lack of competency criterion standardisation of supervisors' assessments brings into question the validity of this assessment method as currently used.

Clinics in diagnostic imaging (138). Emphysematous pyelitis

We present the case of a 49-year-old woman with poorly controlled diabetes mellitus of ten years' duration. She presented to the emergency department with nonspecific left lower abdominal pain. Ultrasonography showed mild left renal hydronephrosis, but the cause was not demonstrated. Computed tomography (CT) showed a swollen left kidney with a mildly dilated collecting system containing gas and dense fluid, confirming the diagnosis of emphysematous pyelitis. Management consisted of emergency antegrade nephrostomy drainage and parenteral antibiotics. Subsequently, the patient made a good recovery and was well when discharged home after two weeks. Gas-forming infections of the genitourinary tract carry high mortality and morbidity, and usually occur in patients with poorly controlled diabetes mellitus. Escherichia coli is the most common microorganism. This case emphasises the importance of CT in making an early diagnosis of emphysematous pyelitis, which allows prompt treatment and improves prognosis.

Supervisor assessment of clinical and professional competence of medical trainees: a reliability study using workplace data and a focused analytical literature review

Even though rater-based judgements of clinical competence are widely used, they are context sensitive and vary between individuals and institutions. To deal adequately with rater-judgement unreliability, evaluating the reliability of workplace rater-based assessments in the local context is essential. Using such an approach, the primary intention of this study was to identify the trainee score variation around supervisor ratings, identify sampling number needs of workplace assessments for certification of competence and position the findings within the known literature. This reliability study of workplace-based supervisors' assessments of trainees has a rater-nested-within-trainee design. Score variation attributable to the trainee for each competency item assessed (variance component) were estimated by the minimum-norm quadratic unbiased estimator. Score variance was used to estimate the number needed for a reliability value of 0.80. The trainee score variance for each of 14 competency items varied between 2.3% for emergency skills to 35.6% for communication skills, with an average for all competency items of 20.3%; the "Overall rating" competency item trainee variance was 28.8%. These variance components translated into 169, 7, 17 and 28 assessments needed for a reliability of 0.80, respectively. Most variation in assessment scores was due to measurement error, ranging from 97.7% for emergency skills to 63.4% for communication skills. Similar results have been demonstrated in previously published studies. In summary, overall supervisors' workplace based assessments have poor reliability and are not suitable for use in certification processes in their current form. The marked variation in the supervisors' reliability in assessing different competencies indicates that supervisors may be able to assess some with acceptable reproducibility; in this case communication and possibly overall competence. However, any continued use of this format for assessment of trainee competencies necessitates the identification of what supervisors in different institutions can reliably assess rather than continuing to impose false expectations from unreliable assessments.

Descending thoracic endovascular aneurysm repair: antegrade approach via ascending aortic conduit

Challenging access situations continue to arise in endovascular aneurysm repair, despite evolving arterial access techniques. We report a modified access approach, where an ascending aortic conduit was successfully used for antegrade delivery of a thoracic endograft to repair a descending thoracic aortic aneurysm, in a patient with previous surgical ligation of the infra-renal aorta.

Primary aortoenteric fistula due to a swallowed twig in a three-year-old child

Aortoenteric fistulae are infrequent causes of gastrointestinal bleeding and usually occur as a late complication of aortic aneurysm repair. Primary aortoenteric fistulae are very rare and most have an aetiological association with atherosclerotic aneurysmal disease.(1,2) We report a primary aortoenteric fistula (PAEF) occurring in a 3 year old as a result of duodenal perforation after ingestion of a twig. To our knowledge this is the first case of a primary aortoenteric fistula reported in a child. Emergency aortic surgery in children needs certain considerations which are briefly discussed.

Indirect comparisons of treatments based on systematic reviews of randomised controlled trials

BACKGROUND

Randomised controlled trials are the most effective way to differentiate between the effects of competing interventions. However, head-to-head studies are unlikely to have been conducted for all competing interventions.

AIM

Evaluation of different methodologies used to indirectly compare interventions based on meta analyses of randomised controlled trials.

METHODS

Systematic review of Cochrane Database of Systematic Reviews, Cochrane Methodology Register, EMBASE and MEDLINE for reports including meta analyses that contained an indirect comparison. Searching was completed in July 2007. No restriction was placed on language or year of publication.

RESULTS

Sixty-two papers identified contained indirect comparisons of treatments. Five different methodologies were employed: comparing point estimates (1/62); comparing 95% confidence intervals (26/62); performing statistical tests on summary estimates (8/62); indirect comparison using a single common comparator (20/62); and mixed treatment comparison (MTC) (7/62). The only methodologies that provide an estimate of the difference between the interventions under consideration and a measure of the uncertainty around that estimate are indirect comparison using a single common comparator and MTC. The MTC might have advantages over other approaches because it is not reliant on a single common comparator and can incorporate the results of direct and indirect comparisons into the analysis. Indirect comparisons require an underlying assumption of consistency of evidence. Utilising any of the methodologies when this assumption is not true can produce misleading results.

CONCLUSIONS

Use of either indirect comparison using a common comparator or MTC provides estimates for use in decision making, with the preferred methodology being dependent on the available data.

Unusual cause of seizures in Singapore: neurocysticercosis

Neurocysticercosis is the commonest cause for adult onset of seizures in developing countries, and is relatively uncommon in Singapore. However, with the influx of foreign workers from developing countries, we need to consider it as a differential diagnosis in our approach to adult-onset seizures in this group of patients. We describe a neurocysticercosis occurring in a 22-year-old Indian man who presented with a single episode of generalised tonic-clonic seizures. Magnetic resonance imaging of the brain showed a well-defined, hypointense lesion in the cortical and subcortical regions of the left frontal lobe with adjacent vasogenic oedema. Following contrast administration, a well-defined ring enhancement was noted, with suggestion of some internal enhancement. Imaging findings were suggestive of neurocysticercosis. Follow-up magnetic resonance imaging of the brain two weeks after treatment showed lesion resolution.

Diabetic fibrous mastopathy

Diabetic fibrous mastopathy is reported in a 37-year-old premenopausal woman. A known case of insulin-dependent diabetes mellitus, she presented with bilateral hard breast lumps, which were suggestive of malignancy on both ultrasonography and mammography. Fine-needle aspiration cytology and core biopsy showed fibrosis. An incisional biopsy further excluded malignancy and was conclusive for diabetic fibrous mastopathy.

Structure-flexoelastic properties of bimesogenic liquid crystals

In this paper, we report on the flexoelastic and viscoelastic ratios for a number of bimesogens compounds with the same generic structure. Values are obtained indirectly by measuring the flexoelectro-optic response in the chiral nematic phase. By varying the molecular structure we alter the bend angle, transverse dipole moment, and length of the molecule. First, to examine the influence of the bend angle we use a homologous series whereby the only alteration in the molecular structure is the number of methylene units in the aliphatic spacer, n . Results show that the flexoelastic ratio, e/K , and the effective flexoelectric coefficient, e , both exhibit an odd-even effect with values for n=odd being greater than that for n=even . This is understood in terms of an increase in the bend angle of the molecule and an increase in the transverse dipole moment. Second, in order to investigate the impact of the dipole moment, we have altered the mesogenic units so as to vary the longitudinal dipole moment and used different linkages in the aliphatic spacer in an attempt to alter the transverse dipole moment. Qualitatively, the results demonstrate that the odd-spaced bimesogen with larger transverse dipole moments exhibit larger flexoelastic ratios.

Is this a variant of Lemierre's syndrome?

Lemierre's syndrome is an oropharyngeal infection leading to secondary septic thrombophlebitis of the internal jugular vein (IJV). It is classically anaerobic in origin and Fusobacterium necrophorum is the commonest pathogen. We report an unusual variant of this condition in a 68-year-man with uncontrolled diabetes mellitus who presented with extensive cellulitis of the left neck. No primary oropharyngeal sepsis was detected. Neck radiographs revealed soft tissue gas and computed tomography confirmed neck space infection with gas formation and complete thrombosis of the left IJV. Klebsiella pneumoniae was isolated from the fluid, tissue and blood samples. Repeated debridement was required until complete healing. Computed tomography of the neck at six months showed resolution of infection, although the vein remained thrombosed. Although the radiological features resemble Lemierre's syndrome, this case differs from it in the absence of oropharyngeal sepsis and presence of background diabetes mellitus. The isolation of Klebsiella pneumoniae as a cause has not been previously described.

Cervical meningioma masquerading as schwannoma: two cases and a review of the literature

Two patients presenting with intradural, extramedullary, transforaminal ''dumbbell-shaped'' tumors are discussed. While imaging studies were strongly suggestive of schwannoma, both patients were diagnosed with meningioma. Presentation, imaging studies, operative intervention and pathology are described. Due to the difficulty in achieving complete resection, and the propensity for recurrence, long-term follow-up is recommended.

Assessment of the spatial heterogeneity of weathering rates in upland catchments using the sodium dominance index and its significance in integrated catchment management

The sodium dominance index was developed to quantify weathering rates and critical loads in Scotland, where atmospheric aerosols of maritime origin dominate over biogeochemical weathering in providing base cation inputs to catchment soils and drainage waters. High sodium dominance in river or lake water indicates low weathering rate. Here, this concept is evaluated using intensive temporal and spatial sampling strategies in two substantial catchments, one in Scotland and the other in central England, with particular reference to detection of groundwater inputs, and to possible problems from road salting in the calibration. In the Dee network, the spatial distribution of sodium dominance reflects the distribution of soil parent material geology, but land use also influences the equations. It is postulated that road density, via winter road salting, influences the sodium dominance calibration in lowland agricultural areas. Although road salting can also be problematic in some upland areas, the index still can provide clear indication of the likely severity of acid flush events in remote upland streams. In the Etherow catchment, sodium dominance varies markedly, sometimes over relatively small distances, reflecting soil type distribution, the occurrence of ground-water inputs to streams, and the influence of water in tributaries above the sampling point.