Prevalence of failure of passive immunity transfer in Australian non-replacement dairy calves.

Failure of passive immunity transfer (FPIT) increases the risk of morbidity and mortality in dairy calves. The prevalence of FPIT in dairy calves has generally been reported to be high, with FPIT estimated to occur in 38%-42% of Australian dairy calves. However, the focus of previous studies has been on replacement heifer calves. Our aim was to assess the prevalence of FPIT in Victorian bobby calves (non-replacement dairy calves). We collected blood samples from 3608 bobby calves at three abattoirs at exsanguination, and measured serum total protein as an indicator of passive transfer. We found that 36% of bobby calves showed evidence of FPIT (serum total protein ≤52 g/L), and 50% of calves had poor or fair passive transfer (<58 g/L). When a subset of calves (from farms with more than five calves in the dataset) was analysed using a linear mixed model, Jersey calves and crossbred/other calves had an estimated 5.3 g/L and 5.1 g/L higher serum total protein concentration, respectively, than Holstein-Friesian calves (P < 0.001). Our results suggest that the prevalence of FPIT in bobby calves at abattoirs is similar to that reported in dairy heifer calves sampled on farms. A high prevalence of FPIT has implications for bobby calf morbidity and mortality, as well as calf viability and profitability for dairy-beef production.

Text-message responsiveness to blood glucose monitoring reminders is associated with HbA1c benefit in teenagers with Type 1 diabetes.

AIMS: To evaluate an 18-month text-messaging intervention in teenagers with Type 1 diabetes and to assess factors associated with text responsiveness and glycaemic benefit. METHODS: Teenagers with diabetes (N = 147), aged 13-17 years, received two-way text reminders at self-selected times to check blood glucose levels and reply with blood glucose results. RESULTS: At baseline, the participants (48% boys, 78% white, 63% pump-treated) had a mean ± sd age of 14.9 ± 1.3 years, diabetes duration of 7.1 ± 3.9 years and HbA1c concentration of 69 ± 12 mmol/mol (8.5 ± 1.1%). The mean proportion of days with ≥1 blood glucose response declined over time (0-6 months, 60 ± 26% of days, 7-12 months, 53 ± 31% of days, 13-18 months, 43 ± 33% of days). Over 18 months, 49% responded with ≥1 blood glucose result on ≥50% of days (high responders). Regression analysis controlling for baseline HbA1c revealed no significant change in HbA1c from baseline to 18 months in high responders (P = 0.54) compared with a significant HbA1c increase in low responders (+0.3%, P = 0.01). In participants with baseline HbA1c ≥64 mmol/mol (≥8%), high responders were 2.5 times more likely than low responders to have a clinically significant [≥5.5 mmol/mol (≥0.5%)] HbA1c decrease over 18 months (P < 0.05). In participants with baseline HbA1c <64 mmol/mol(<8%), high responders were 5.7 times more likely than low responders to have an 18-month HbA1c <58 mmol/mol (<7.5%; P < 0.05). CONCLUSIONS: Teenagers with Type 1 diabetes who responded to text reminders on ≥50% of days over 18 months experienced clinically significant glycaemic benefit. There remains a need to tailor interventions to maintain teenager engagement and optimize improvements.

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.

A review of recent developments in buffalo reproduction - a review.

The buffalo is an important livestock resource in several countries of South Asia and the Mediterranean regions. However, reproductive efficiency is compromised due to known problems of biological and management origins, such as lack of animal selection and poor nutrition. Under optimal conditions puberty is attained at 15 to 18 months in river buffalo, 21 to 24 months in swamp buffalo and is influenced by genotype, nutrition, management and climate. However, under field conditions these values deteriorate up to a significant extant. To improve reproductive efficiency, several protocols of oestrus and ovulation synchronization have been adopted from their use in commercial cattle production. These protocols yield encouraging pregnancy rates of (30% to 50%), which are comparable to those achieved in buffaloes bred at natural oestrus. The use of sexed semen in buffalo heifers also showed promising pregnancy rates (50%) when compared with conventional non-sexed semen. Assisted reproductive technologies have been transferred and adapted to buffalo but the efficiency of these technologies are low. However, these latest technologies offer the opportunity to accelerate the genetic gain in the buffalo industry after improving the technology and reducing its cost. Most buffaloes are kept under the small holder farming system in developing countries. Hence, future research should focus on simple, adoptable and impact- oriented approaches which identify the factors determining low fertility and oestrus behaviour in this species. Furthermore, role of kisspeptin needs to be explored in buffalo.

Selecting an appropriate genetic evaluation model for selection in a developing dairy sector.

This study aimed to identify genetic evaluation models (GEM) to accurately select cattle for milk production when only limited data are available. It is based on a data set from the Pakistani Sahiwal progeny testing programme which includes records from five government herds, each consisting of 100 to 350 animals, with lactation records dating back to 1968. Different types of GEM were compared, namely: (1) multivariate v. repeatability model when using the first three lactations, (2) an animal v. a sire model, (3) different fixed effects models to account for effects such as herd, year and season; and (4) fitting a model with genetic parameters fixed v. estimating the genetic parameters as part of the model fitting process. Two methods were used for the comparison of models. The first method used simulated data based on the Pakistani progeny testing system and compared estimated breeding values with true breeding values. The second method used cross-validation to determine the best model in subsets of actual Australian herd-recorded data. Subsets were chosen to reflect the Pakistani data in terms of herd size and number of herds. Based on the simulation and the cross-validation method, the multivariate animal model using fixed genetic parameters was generally the superior GEM, but problems arise in determining suitable values for fixing the parameters. Using mean square error of prediction, the best fixed effects structure could not be conclusively determined. The simulation method indicated the simplest fixed effects structure to be superior whereas in contrast, the cross-validation method on actual data concluded that the most complex one was the best. In conclusion it is difficult to propose a universally best GEM that can be used in any data set of this size. However, some general recommendations are that it is more appropriate to estimate the genetic parameters when evaluating for selection purposes, the animal model was superior to the sire model and that in the Pakistani situation the repeatability model is more suitable than a multivariate.

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.

Effect of pre-weaning feeding regimens on post-weaning growth performance of Sahiwal calves.

The objective of the study was to assess the post-weaning growth response of Sahiwal calves reared on four different pre-weaning dietary regimens. The four diets were: (a) whole cow's milk, starter ration (SR; CP = 20%, total digestible nutrients (TDN) = 72%) and Berseem hay (H; Egyptian clover; CP = 21%, TDN = 63%); (b) whole cow's milk + H; (c) milk replacer (MR; reconstituted to supplier specification; Sprayfo®) + SR + H; and (d) MR + H. The protein and fat percentages of reconstituted MR were 2.22 and 1.84, respectively. Milk or MR were fed at the rate of 10% of the calves' body weight (BW) until 56 days of age, and then withdrawn gradually until weaned completely by 84 days of age. The average initial BW of calves in groups A, B, C and D were 56.3 ± 1.0, 47.5 ± 1.0, 40.4 ± 1.0 and 30.3 ± 1.0 kg, respectively. Initially, there were 12 calves in each group with six of each sex; however, one male calf died from each of groups B and C and were not replaced. During the post-weaning period, 13 to 24 weeks, the calves were fed a single total mixed ration ad libitum based on maize, canola meal, wheat straw and molasses containing 16% CP and 70% TDN. Daily feed intake and weekly BW gains were recorded. The data were analyzed by MIXED model analysis procedures using the statistical program SAS. The intake of calves as percent of their BW, feed conversion ratio and cost per kg of BW gain were not different (P > 0.05) across treatments. The daily gain at 24 weeks of age for the pre-weaning treatments A, B, C and D were 746 ± 33, 660 ± 33, 654 ± 33 and 527 ± 33 g/day and the final liveweights of calves were 119 ± 4.2, 102 ± 4.2, 95 ± 4.2 and 75 ± 4.2 kg, respectively. Gains were influenced significantly (P < 0.05) by pre-weaning treatments. The calves fed MR and H only during the pre-weaning period were unable to catch up post weaning with calves on other dietary treatments. The calves fed whole milk from birth at the rate of 10% of liveweight together with concentrates had higher weaning weight and superior growth rate post weaning as well. Thus, pre-weaning feeding was important for higher weaning weights and superior growth rates post weaning.

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.

Prognostic efficacy of cardiac biomarkers for mortality in dialysis patients.

BACKGROUND: The high prevalence of cardiovascular mortality in the end-stage renal disease population is well established. The aim of this current study was to document the relative prognostic significance of established cardiac biomarkers troponin T (TnT), troponin I (TnI), B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-pro-BNP) in this population. METHODS: A prospective cohort study of dialysis patients undertaken in a single tertiary centre in Australia. Relevant clinical and biochemical information was collected at entry and all patients followed up prospectively without any loss to follow up. End-point of interest was all-cause mortality. Statistical analysis using Cox proportional hazards was used to study relationship between competing covariates and outcome. A total of 143 patients with a mean age of 59.67 +/- 15.49 years was followed up for a median duration of 30 months. Of these patients, 89.3% were white Australians of European ancestry. Twenty-seven per cent had an established diagnosis of diabetes mellitus. The mean concentrations (+/-SD) of TnT, TnI, BNP and N-terminal peptide pro-BNP (NT-pro-BNP) were 0.08 +/- 0.04 microg/L, 0.09 +/- 0.2 microg/L, 270 +/- 117 ng/L and 1434 +/- 591 ng/L respectively. RESULTS: Twenty-eight subjects died during the period of follow up. By univariate analysis, all cardiac markers (TnT, TnI, BNP, NT-pro-BNP and C-reactive protein) were significantly associated with an increase in mortality. On Cox proportionate hazards analysis, only albumin and NT-pro-BNP showed a significant association with mortality, with hazard ratios of 0.834, 95% confidence interval (CI) 0.779-0.893, P < 0.001, and 1.585, 95%CI 1.160-20165, P = 0.004 respectively. CONCLUSION: In patients with end-stage renal failure on dialysis NT-pro-BNP provides greater prognostic information compared with TnT and TnI.

A randomised, split-face comparison of facial hair removal with the alexandrite laser and intense pulsed light system.

INTRODUCTION: Despite the high incidence of polycystic ovary syndrome (PCOS) in women attending for facial hair removal there are few studies looking specifically at this patient group. We carried out a split-face study directly comparing the efficacy of a 3 milliseconds pulse duration alexandrite laser with the Lumina IPL system in 38 women with PCOS. MATERIALS AND METHODS: Each patient underwent six treatments using both systems, with 1, 3 and 6 months follow-up. Hair counts, hair-free intervals and patient satisfaction were recorded for all patients. RESULTS: After six treatments, alexandrite laser treatment resulted in longer median hair-free intervals when compared to IPL (7 weeks vs. 2 weeks; P < 0.001). Decrease in hair counts was significantly larger on the Alexandrite side compared to the IPL side at 1, 3 and 6 months (52%, 43% and 46% vs. 21%, 21% and 27%; P < 0.001). Patient satisfaction scores, using linear analogue scales (LAS), at 1, 3 and 6 months were significantly higher for the alexandrite laser than the IPL (8.7, 7.8 and 7.7 vs. 5.7, 5.1 and 5.1; P < or = 0.002). CONCLUSIONS: The alexandrite laser resulted in significantly longer hair-free intervals, a larger reduction in hair counts and greater patient satisfaction than the IPL and appeared to be more effective in this patient group. It is clear from the results in this study that the GentleLase alexandrite laser is more effective at reducing facial hirsutism in women with PCOS than the Lumina IPL. It is probable that this is due to the specific wavelength, short pulse duration and single pulse delivery of the GentleLase alexandrite laser, resulting in more follicular destruction than the IPL.

Assessment of burn depth: a prospective, blinded comparison of laser Doppler imaging and videomicroscopy.

INTRODUCTION AND AIMS: There is a need, both in clinical and research settings, for an affordable, objective method of assessing burn depth. This study compares burn depth assessment by videomicroscopy with laser Doppler imaging (LDI) in patients with dermal burns. The videomicroscope is inexpensive compared to LDI, and can visualise the dermal capillary structure, therefore potentially allowing objective assessment of dermal burn injuries. METHODS: Patients admitted <72 h post-injury were included in the trial. Blinded LDI and videomicroscopy assessments were carried out. The patients were then followed up to one of three end-points: primary healing without surgery; early surgery; delayed healing and subsequent split skin grafting. The incidence of infection was also noted. RESULTS: Twenty-seven burn wounds were examined. In superficial partial thickness injuries, the videomicroscope reliably demonstrated an intact or nearly intact dermal vascular structure, progressing through to large amounts of capillary destruction and haemoglobin deposition in deep partial thickness injuries and complete destruction in full thickness injuries. The videomicroscope findings correlated strongly with both those of the LDI (p<0.001) and with clinical outcome (p<0.001). DISCUSSION: The videomicroscope is capable of accurately and objectively assessing burn depth. The results correlated well with both the clinical outcome and the laser Doppler findings. In addition, videomicroscopy is significantly cheaper than LDI and avoids several of the disadvantages of LDI.

Laser hair removal in women with polycystic ovary syndrome.

UNLABELLED: Polycystic ovary syndrome (PCOS) is one of the most common reasons for women to present seeking removal of facial hair, particularly within the UK National Health Service (NHS). In the NHS, there is geographical variation in the number of laser treatments available to women with PCOS, with some units limiting patients to six treatments whilst others allow unlimited treatments. This study aims to assess the effect of number of treatments on women with PCOS. METHODS: This study prospectively assessed hair counts, hair-free intervals and patient satisfaction in 60 women with PCOS undergoing 3ms pulse duration alexandrite laser treatment. RESULTS: Following six treatments there was a mean 31+/-38% reduction in hair counts (mean+/-SD; P=0.001). Mean hair-free interval (HFI) increased steadily with treatment, from 1.9 weeks after six treatments to 4.3 weeks after 10 treatments (P=0.001). From the postal questionnaire, after an average of 12 treatments, 31% of patients had a HFI longer than 6 weeks compared to only 2.6% after six treatments (P=0.003). Overall, despite the low hair count reductions, 95% of patients were satisfied with treatment. CONCLUSION: In women with PCOS, laser treatment is associated with a poorer than expected reduction in hair counts and HFI following treatment. However, offering more than six treatments does have additional benefits in terms of prolonging HFI and overall patient satisfaction with treatment is very high.

The effect of ambient temperature on capillary vascular malformations.

BACKGROUND: Following pulsed dye laser (PDL) treatment of capillary vascular malformations (CMs), the capillaries left behind tend to be smaller and deeper. The PDL is most effective against capillaries over 50 microm, suggesting that clearance of CM could be improved by inducing capillary vasodilation of the smaller remaining capillaries. However, there are reduced perivascular nerves within CMs, implying that autonomic innervation to these capillaries may be abnormal. OBJECTIVES: To investigate whether CM capillaries will vasodilate in response to autonomic stimulation by raising ambient temperature. METHODS: Ten patients with untreated CMs and nine with previously laser-treated CMs were studied as ambient temperature was increased from 20 degrees C to 28 degrees C. The following measurements were taken at 2 degrees C intervals: skin blood flow (SBF); capillary diameter and depth; CM colour; and skin and core temperatures. RESULTS: All the subjects studied demonstrated superficial capillary vasodilation and increased SBF as the ambient temperature was raised from 20 degrees C to 28 degrees C. Mean+/-SEM capillary diameter increased from 66+/-7 microm to 110+/-13 microm (P<0.001) in the untreated group, compared with an increase from 28+/-5 microm to 70+/-14 microm (P<0.001) in the treated group. Mean+/-SEM SBF increased from 427.2+/-98.2 perfusion units (PU) to 580.9+/-92.7 PU (P<0.01) in the untreated group, compared with an increase from 201.3+/-28.4 PU to 458.1+/-53.7 PU (P<0.05) in the treated group. CONCLUSIONS: Superficial capillary vasodilation within CM is achievable by raising ambient temperature, including in those patients resistant to PDL treatment, potentially allowing further clearance of these lesions.

Use of personal digital assistants for retrieval of medical images and data on high-resolution flat panel displays.

For its new acute care hospital, the University of California at Los Angeles is evaluating innovative technology involving high-resolution flat panel display devices configured as "network appliances" that can be wall mounted for use in the retrieval and display of medical images and data. Physicians and healthcare providers can log on with wireless handheld computers, which can serve as an identification device as well as a navigational tool for selecting patient records and data. These data are displayed and manipulated on the flat panel display without the need for a keyboard or mouse. A prototype was developed with commercially available image display software, which was modified to allow the remote control of software functions from a handheld device through an infrared communication port. The system also allows navigation through the patient data in a World Wide Web-based electronic patient record. This prototype illustrates the evolution of radiologic facilities toward "shareable" high-quality display devices that allow more convenient and cost-effective access to medical images and related data in complex clinical environments, resulting in a paradigm shift in data navigation and accessibility.

Liver biopsy: when, how, by whom, and where?

Liver biopsy remains an important diagnostic tool in the management of liver disease. Complications, though infrequent, are potentially disastrous. Risks and discomfort can be minimized with good technique, although prospective data to prove the superiority of one method over another are often lacking. Image direction is preferred in all cases, as is a transjugular approach when bleeding risks are judged to be high. Bleeding is essentially a random event. Outpatient liver biopsy is appropriate in almost every instance if immediate hospitalization facilities are available. It should be more widely practiced. Liver biopsies should only be done if, after thoughtful assessment, benefits are thought to exceed risks.

An assessment of the role of liver biopsies in asymptomatic patients with chronic liver test abnormalities.

OBJECTIVE: The role of liver biopsy in the management of patients with nonspecific chronic liver enzyme abnormalities is not well established. The aim of this study is to determine whether liver histology changes the clinical impression formed before liver biopsy and the preliminary management plan. METHODS: Consenting asymptomatic adult patients with persistent (> or = 6 months) liver test abnormalities were enrolled. Patients with a strong suspicion for a specific liver disease were excluded. A presumptive diagnosis and a preliminary management plan were documented before a liver biopsy. After the liver biopsy, the patients were reassessed to determine the effect of the biopsy on the diagnosis and management plan. RESULTS: A total of 36 patients were enrolled: 15 men and 21 women, with a median age of 51 yr. The prebiopsy diagnoses were nonalcoholic steatohepatitis (24), autoimmune hepatitis (3), primary biliary cirrhosis (2), primary sclerosing cholangitis (2), and miscellaneous (5 patients). The liver biopsy changed the diagnosis in 14% of cases. Lifestyle recommendations were not significantly altered by the biopsy. The liver biopsy affected the frequency of liver test monitoring in 13 patients (36%). Treatment recommendations were affected in 12 cases, 10 of whom were offered investigational therapy. CONCLUSIONS: Although a liver biopsy may help to definitively establish the final diagnosis in patients, the results alter the presumptive prebiopsy diagnosis infrequently, and no proven therapy exists for the vast majority of these patients. Therefore, the risks and benefits of a liver biopsy should be carefully weighed, especially in settings in which investigational therapies are unavailable.

Magnetic resonance imaging-guided neurosurgery in the magnetic fringe fields: the next step in neuronavigation.

OBJECTIVE: We describe the development of an alternative approach to intraoperative magnetic resonance imaging (iMR)-guided neurosurgery and report our initial experience with 22 craniotomies and 16 brain biopsies. The advantages and disadvantages of each approach are examined. METHODS: An iMR suite houses a 0.2-T open configuration system (Siemens Medical Systems, Erlangen, Germany) and is equipped with anesthetic gases and a magnetic resonance imaging (MRI)-compatible anesthesia machine and monitor. Standard operating instruments and equipment were tested for safety and compatibility in the magnetic fringe fields surrounding the open MRI system. We then performed brain biopsies and craniotomies in the iMR suite. RESULTS: Standard operating equipment functioned properly in the 0.5- to 10-mT zone and was not affected by the magnet's attractive force. Twenty-two craniotomies and 16 brain biopsies were performed in the interventional suite, using serial intraoperative MRI guidance, without injury to patients or operating room staff. CONCLUSION: Full neurosurgical procedures may be performed in the weak fringe fields surrounding an MRI system, using standard operating room equipment. This approach to iMR-guided neurosurgery offers a significant cost advantage over retrofitting an entire operative suite with "MRI-compatible" surgical equipment. The surgeon's familiarity with standard equipment and the reliability of the equipment are additional advantages. Neurosurgery in the fringe fields allows the neurosurgeon to utilize serial MRI with a minimum of inconvenience, disruption, and change to the standard neurosurgical procedure. Serial intraoperative imaging to visualize the changes in the brain that are associated with neurosurgical intervention seems to enhance the ability to safely and effectively accomplish neurosurgical goals.

Selective neck dissections for squamous carcinoma of the upper aerodigestive tract: patterns of regional failure.

BACKGROUND: Surgeons have been using selective neck dissections in the treatment of squamous carcinoma of the upper aerodigestive tract for over 20 years. To date, no data is available that can answer the question "What are the patterns of failure in the neck following a selective neck dissection and is a selective neck dissection a reliable procedure for metastatic disease?" METHODS: To answer this question, the medical records of all patients with squamous carcinoma of the oral cavity, oropharynx, larynx, and hypopharynx treated at The University of Texas M. D. Anderson Cancer Center from January 1, 1985-December 31, 1990, with a selective neck dissection were reviewed. Five hundred seventeen neck dissections were analyzed: suprahyoid (41), supraomohyoid (284), and anterolateral (192). The end point of the study was regional failure and survival. RESULTS: Regional recurrence in patients treated with a suprahyoid dissection was 43% with pathologically positive nodes. The regional recurrence in the patients treated with a supraomohyoid neck dissection was 1.9% with pathologically negative nodes, 35.7% with path N1 without postoperative radiation therapy, and 5.6% with postoperative radiation therapy. The neck staged pathologically N2B failed with and without postoperative radiation, 8.3% and 14%, respectively. Thirteen percent of the anterior/lateral neck dissections failed regionally. If multiple pathologically positive nodes (N2B) were present, the regional failure with postoperative radiation was 30% and 33.3% without postoperative radiation. CONCLUSION: The results of this retrospective study suggest that a selective neck dissection is a satisfactory staging procedure and is a definitive operation if all the nodes are pathologically negative. However, if a node is found to be invaded with cancer, the use of postoperative radiation is advisable.

Anticoagulant therapy, anti-platelet agents and gastrointestinal endoscopy.

BACKGROUND: The increasing use of anticoagulant therapy and anti-platelet agents in the primary and secondary prevention of cardiovascular, cerebrovascular and venous thromboembolic disease has increased the need for guidelines for managing these agents prior to gastrointestinal endoscopy, particularly if therapeutic manoeuvres are required. The continuation of anticoagulant therapy increases the risk of haemorrhagic complications of gastrointestinal endoscopy. Temporary suspension of anticoagulant therapy exposes the patient to the risk of thromboembolism associated with the underlying condition requiring anticoagulant treatment. CONCLUSIONS: This article reviews the literature and proposes guidelines for the management of patients taking anticoagulant and anti-platelet agents who require gastrointestinal endoscopy.