Informed consent for stochastic effects of ionising radiation in diagnostic imaging

The ethical and legal principles underpinning the requirement for informed consent for medical procedures are widely accepted. A recent BJR article has applied these principles to the issue of consent to ionising radiation (IR) from diagnostic imaging (DI), but the authors chose to put aside the practical problems associated with this. These problems should not be underestimated and arise from: uncertainties about the existence and magnitude of risk of stochastic effects of IR exposure in DI; the delayed manifestation of its effects; the heterogeneity of risk related to factors associated with individual sensitivity to IR, and dose variation even within examination classes and across clinical indications; and the difficulty of communication of these uncertainties and variations to patients. This article discusses these practical issues associated with consent for IR in DI.

Painless Visible Haematuria in Adults: An Algorithmic Approach Guiding Management

There is consensus that visible haematuria may be a sign of serious underlying disease, including malignancy, and warrants a thorough diagnostic evaluation. This is usually undertaken by a combination of clinical examination, cystoscopic evaluation, and urinary tract imaging.

A decision support tool has been developed in the form of an algorithmic flow chart as part of a suite of on-line evidence-based and consensus-based guidelines Diagnostic Imaging Pathways (DIP): www.imagingpathways.health.wa.gov.au (Online clinical decision-making tool: Dulku G. Painless Macroscopic Haematuria. Diagnostic Imaging Pathways; September 2015) to provide imaging recommendations for adult patients with unexplained, painless visible haematuria. A literature review, including reference to several international consensus-based expert guidelines, has been employed to develop this tool.

The choice of first line imaging method is dependent on the risk stratification into high or low risk for the development of renal and urologic malignancies. Ultrasound is vital in the initial assessment of haematuria particularly in radiation sensitive patients, low-risk patients, and in young men <40 years. Computed tomographic urography (CTU) is a sensitive and specific method for the detection of urothelial malignancy particularly in high-risk patients. Magnetic resonance urography (MRU) provides better contrast resolution than CTU without exposure to ionising radiation or requiring intravenous (IV) contrast administration, making it more suitable for examination of paediatric and pregnant patients and patients with renal impairment. Cystoscopy remains the gold standard in the detection of lower urinary tract (bladder) urothelial tumours.

Until randomised clinical trials comparing different diagnostic modalities or strategies prospectively and outcome studies are available, consensus-based practice recommendations similar to ours are nonetheless warranted to reduce the variation in haematuria management.

Preoperative Gastric Residual Volumes in Fasted Patients Measured by Bedside Ultrasound: A Prospective Observational Study

The purpose of this prospective observational study was to measure gastric volumes in fasted patients using bedside gastric ultrasound. Patients presenting for non-emergency surgery underwent a gastric antrum assessment, using the two-diameter and free-trace methods to determine antral cross-sectional area. Gastric residual volume (GRV) was calculated using a validated formula. Univariate and multivariable analyses were performed to examine any potential relationships between ‘at risk’ GRVs (>100 ml) and patient factors. Two hundred and twenty-two successful scans were performed; of these 110 patients (49.5%) had an empty stomach, nine patients (4.1%) had a GRV >100 ml, and a further six patients (2.7%) had a GRV >1.5 ml/kg. There was no significant relationship between ‘at risk’ GRV and obesity, diabetes mellitus, gastro-oesophageal reflux disease or opioid use, although our study had insufficient power to exclude an influence of one or more of these factors. Our results indicate that despite compliance with fasting guidelines, a small percentage of patients still have GRVs that pose a pulmonary aspiration risk. Anaesthetists should consider this background incidence when choosing anaesthesia techniques for their patients. While future observational studies are required to determine the role of preoperative bedside gastric ultrasound, it is possible that this technique may assist anaesthetists in identifying patients with ‘at risk’ GRVs.

Targeted Robotic Assisted Microsurgical Denervation of the Spermatic Cord for the Treatment of Chronic Orchialgia or Groin Pain: A Single Center, Large Series Review

PURPOSE

Microsurgical denervation of the spermatic cord is a treatment option for chronic orchialgia refractory to conservative treatment. A recent study showed specific nerve fibers as the possible cause of chronic orchialgia. Our goal was to present the outcomes of ligation of these nerves using a technique of targeted robotic assisted microsurgical denervation of the spermatic cord.

MATERIALS AND METHODS

We retrospectively reviewed the records of 772 patients who underwent targeted robotic assisted microsurgical denervation of the spermatic cord from October 2007 to July 2016. Selection criteria were chronic testicular pain more than 3 months in duration, failed conservative treatments, negative neurological and urological workup, and temporary resolution of pain with a local anesthetic spermatic cord block. Targeted robotic assisted microsurgical denervation of the spermatic cord was performed. Pain was assessed preoperatively and postoperatively using a subjective visual analog scale and objectively with the standardized and validated PIQ-6 (Pain Impact Questionnaire-6) score.

RESULTS

Followup data were available on 860 cases. During a median followup of 24 months (range 1 to 70) 718 cases (83%) showed a significant reduction in pain and 142 (17%) had no change in pain by subjective visual analog scale scoring. Of cases with a significant reduction in pain 426 (49%) had complete resolution and 292 (34%) had a 50% or greater reduction. Objective PIQ-6 analysis showed a significant reduction in pain in 67% of patients 6 months postoperatively, in 68% at 1 year, in 77% at 2 years, in 86% at 3 years and in 83% at 4 years.

CONCLUSIONS

Targeted robotic assisted microsurgical denervation of the spermatic cord is an effective, minimally invasive approach with potential long-term durability in patients with refractory chronic orchialgia.

Imaging for chronic abdominal pain in adults

Diagnostic imaging is often not indicated in chronic abdominal pain. In particular, undifferentiated abdominal pain is rarely an indication for a CT scan. CT scanning is overused even when imaging is required. Other modalities may be preferable. A normal CT scan does not rule out cancer. Alarm symptoms, including anaemia, blood in the stool, waking at night with gastrointestinal symptoms, and weight loss, should be investigated. The most appropriate modality depends on the symptoms. Clinical information on request forms for CT scans should be specific and include the suspected condition as this helps the radiologist to determine an appropriate imaging protocol.

Pulmonary embolism: are we there yet?

INTRODUCTION

Clinical prediction rules (such as Wells model) are a reliable assessment tool for diagnostic work-up of suspected pulmonary embolism (PE). When used as part of a clinical algorithm and in combination with a D-Dimer, the model can safely exclude PE in low-risk groups and indicate when further investigations are unnecessary. The purpose of this study was to investigate the level of adherence to local diagnostic imaging guidelines for suspected PE and to ascertain the impact of interventions.

METHODS

Retrospective search of all patients referred from the Emergency Department (ED) of Royal Perth Hospital for computed tomography pulmonary angiography (CTPA) or V/Q scan between 11 September 2005 to 10 March 2006 (pre-intervention) and 1 January 2008 to 31 March 2008 (post-intervention) was conducted. The guidelines on 'Diagnostic Imaging Pathways' were considered as gold standard. Interventions included orienting ED doctors to guidelines and modified request forms for mandatory completion of Wells score. A prevalence- and bias-adjusted kappa (PABAK) score analysed the level of agreement between documentation on notes (R-score) and stamp (S-score).

RESULTS

Thirty-five per cent (n = 187) and 22% (n = 109) deviated from the pathway pre-intervention and post-intervention, respectively (13% absolute reduction; P = 0.017). Stamp compliance was only 55% despite mandatory filling requirement. PABAK for 'PE as most likely diagnosis' was 0.25 for V/Q group and - 0.26 for CTPA. In addition, 44/60 (73%) had an intermediate or high S-score, yet only 11 of those 44 had a matched intermediate to high R-Score.

CONCLUSIONS

Interventions reduced inappropriate practice but did not eliminate it completely. Compliance issues may be managed in the future via the introduction of electronic request linked to decision support.

CT grading scales for splenic injury: why can't we agree?

INTRODUCTION

Computed tomography (CT) has been proven to be able to accurately diagnose splenic injury. Many have published CT splenic injury grading scales to quantify the extent of injury. However, these scales have failed at predicting clinical outcomes and therefore cannot be used to accurately predict the need for intervention. We hypothesised that low interrater reliability is the reason why these scales have failed at predicting clinical outcomes.

METHODS AND MATERIALS

This is a retrospective study of patients who were admitted to the Royal Perth Hospital with blunt splenic injury as coded in the trauma registry. The abdominal CT images of these patients were reviewed by three consultant radiologists and were graded using the six different splenic injury grading scales. We assessed interrater reliability between each of the scales using generalised kappa and proportion of agreement calculations.

RESULTS

The images of 64 patients were reviewed. The interrater reliability yielded a generalised kappa score of 0.32-0.60 and proportion of agreement ranging from 34.4% to 65.5%.

CONCLUSION

The six studied CT splenic injury grading scales did not have a high enough interrater reliability to be adequate for clinical use. The poor interrater reliability is likely to contribute to the failure of the scales at predicting clinical outcomes. Further research to improve the interrater reliability is recommended.

Case report: Confined penetration of a duodenal ulcer causing pancreatitis

Confined penetration of a duodenal ulcer is an unusual cause of pancreatic gas and pancreatitis.

Non-invasive prediction of the degree of liver fibrosis in patients with hepatitis C using an ultrasound contrast agent. A pilot study

It has been shown that the severity of hepatic fibrosis in patients with hepatitis C can be predicted non-invasively by measuring intrahepatic circulatory time (IHCT) using a microbubble agent with spectral Doppler analysis. The aim of this study was to assess whether this technique is reproducible using a third-generation microbubble agent and contrast harmonic imaging, which are becoming the standard ultrasound techniques in all radiology departments. Twenty-three untreated patients with hepatitis C, who had undergone a recent liver biopsy, were studied prospectively. Based on their histological fibrosis score, patients were divided into four groups (fibrosis levels 1-4). Contrast harmonic imaging was carried out after an intravenous bolus of a microbubble agent (Optison; Amersham Health, Milwaukee, WI, USA). IHCT was calculated by measuring the difference between the hepatic vein and hepatic artery microbubble arrival times. The IHCT was compared with the degree of fibrosis. Significant differences were shown between the groups for IHCT. There were significant differences between fibrosis levels 1 and 3 and between fibrosis levels 1 and 4. This study has shown that calculation of IHCT using a third-generation microbubble agent and contrast harmonic imaging can differentiate mild fibrosis from more severe degrees of fibrosis in patients with hepatitis C.

Computed tomographic colonography: prevalence, nature, and clinical significance of extracolonic findings in a community screening program

OBJECTIVE

Colorectal neoplasia screening by computed tomographic colonography (CTC) may lead to the detection of incidental extracolonic findings. We report the prevalence and clinical significance of extracolonic pathology found within a community-based CTC screening program and the cost of clinical follow-up and further investigation of these findings.

METHODS

A total of 432 asymptomatic subjects at an average risk of colorectal neoplasia, aged 50-69, had screening by CTC using a low radiation dose protocol. Axial images were prospectively examined for extracolonic lesions and those considered clinically relevant were followed up. All clinic visits and further investigations were tallied to calculate the incremental cost to the screening CTC.

RESULTS

A total of 146 extracolonic lesions were detected in 118 (27.3%) subjects. Thirty-two (7.4%) subjects had clinically relevant extracolonic abnormalities and nine (2.1%) subjects may derive a clinical benefit from the detection of these lesions. A single CTC costed $171.12, and following up extracolonic findings resulted in an additional $24.37 (14.2%) per CTC. Limiting reporting to the aorta and kidneys would have reduced the number of subjects requiring follow-up to 14 (3.2%), and decreased the cost increment to 4.7% without detriment to clinical outcome.

CONCLUSIONS

Extracolonic findings of screening CTC are common, but infrequent of clinical importance. The additional burden of following up these findings was modest and could have been further reduced if clear clinical and radiological criteria and pathways for their further investigation were defined.

Diagnostic imaging pathways: development, dissemination, implementation, and evaluation

ISSUE

There are signs of inappropriate application of medical imaging to diagnosis. Inappropriate imaging is a threat to effective diagnosis and effective allocation of resources. The development and deployment of knowledge-based clinical decision support systems is one strategy to reduce inappropriate imaging. DEVELOPMENT OF IMAGING PATHWAYS: A suite of 78 imaging pathways was conceived both as a decision support and educational tool. The pathways were drafted by imaging specialists, but further developed and modified, based on graded evidence and input from requesting clinicians. An electronic environment was developed to contain and deliver the pathways. DISSEMINATION AND IMPLEMENTATION: Imaging pathways were distributed via a hospital local area network and on compact disk. A multifaceted approach was used to raise general awareness of the pathways, followed by intensive 'marketing' activities. Two groups of clinicians were targeted; hospital-based clinicians and general practitioners.

EVALUATION

There was increased awareness of imaging pathways. Clinicians judged them to be useful for education and decision support. The method of electronic delivery was adequate. Knowledge of diagnostic imaging and requesting behaviour tended to become more aligned with the pathways. The central objective to reduce inappropriate medical imaging seems to be achievable.

LESSONS LEARNED

There is scope to improve the content and the electronic environment, achieve better integration into decision-making processes, and achieve better compliance. A linkage between imaging pathways and electronic requesting could provide alerts to 'non-compliant' requesting. The assignment of a higher cost, or a lower remuneration, to non-authorized and non-compliant imaging would provide tangible incentive to comply, unless there are compelling clinical contraindications.

Virtual colonoscopy: Issues in implementation

The following issues and requirements related to the implementation of a CT colonography (CTC) service are important: (i) policies are needed regarding the indications for CTC. Concomitant with this is the need for education of potential referrers and patients. Expectations of the procedure, particularly by general practitioners, may be unrealistic and indications for referral may otherwise be inappropriate. At present there is not general acceptance of CTC for screening asymptomatic persons; (ii) a flexible approach to CT protocols is useful, dependent on the indication for and clinical context of referral, the age and body habitus of the patient; (iii) attention to the issues related to the special skills required by the reporting radiologist. While there is a temptation to regard CTC interpretation as an extension of skills used in interpreting other cross-sectional images, there is a need to realise that there are skills required specific to CTC and there should be adequate provision for training; (iv) matters related to reporting, such as reporting format, and lesions that will be reported/not reported; and (v) informed consent from the patient. Information should be provided with regard to the limitations of CTC, the implications of a positive finding and radiation dosage.

Identification and staging of pancreatic tumours using computed tomography, endoscopic ultrasound and mangafodipir trisodium-enhanced magnetic resonance imaging

Pancreatic malignancy can be staged by a number of different investigations, either alone or in combination. The purpose of the present study was to compare the use of endoscopic ultrasound, CT and mangafodipir trisodium-enhanced MRI for the staging of pancreatic malignancy, particularly with respect to determining resectability prior to surgery. Twenty-seven patients referred for the investigation of a suspected pancreatic malignancy were entered into the trial. All patients had contrast-enhanced CT, gadolinium and mangafodipir trisodium-enhanced MRI, and endoscopic ultrasound (EUS). Images were assessed for nodal staging, tumour staging and resectability for each investigation, and the results compared with findings at surgery. The results for the accuracy of MRI, CT and EUS, in detecting T4 disease versus T3 or lower was 78, 79 and 68%, respectively; nodal involvement was 56, 63 and 69%, respectively; and overall resectability (including the T stage, presence of involved nodes and metastases) was 83, 76 and 63%, respectively. There was no significant difference demonstrated between the three tests. The present study suggests that for patients referred for investigation and staging of pancreatic malignancy, EUS and MRI scanning convey little advantage over contrast-enhanced CT. Furthermore, although mangafodipir trisodium improved the conspicuity of pancreatic tumours, it has little influence on T staging.

Pancreatic islet cell tumours presenting as recurrent acute pancreatitis: imaging features in three cases

We present three cases of recurrent pancreatitis that occurred in patients with small islet cell tumours of the pancreas which were obstructing the main pancreatic duct. This is a very uncommon presentation of pancreatic islet cell tumours. The radiological findings in these cases are shown and the implications for imaging of 'idiopathic' relapsing pancreatitis are discussed.

Lifestyle modifications to prevent and control hypertension. 2. Recommendations on obesity and weight loss. Canadian Hypertension Society, Canadian Coalition for High Blood Pressure Prevention and Control, Laboratory Centre for Disease Control at Health Canada, Heart and Stroke Foundation of Canada

OBJECTIVE

To provide updated, evidence-based recommendations concerning the effects of weight loss and maintenance of healthy weight on the prevention and control of hypertension in otherwise healthy adults (except pregnant women).

OPTIONS

The main options are to attain and maintain a healthy body weight (body mass index [BMI] 20-25 kg/m2) or not to do so. For those at risk for hypertension, weight loss and maintenance of healthy weight may prevent the condition. For those who have hypertension, weight loss and maintenance of healthy weight may reduce or obviate the need for antihypertensive medications.

OUTCOMES

The health outcome considered was change in blood pressure. Because of insufficient evidence, no economic outcomes were considered.

EVIDENCE

A MEDLINE search was conducted for the years 1992-1996 with the terms hypertension and obesity in combination and antihypertensive therapy and obesity in combination. Other relevant evidence was obtained from the reference lists of the articles identified, from the personal files of the authors and through contacts with experts. The articles were reviewed, classified according to study design and graded according to level of evidence.

VALUES

A high value was placed on the avoidance of cardiovascular morbidity and premature death caused by untreated hypertension.

BENEFITS, HARMS AND COSTS

Weight loss and the maintenance of healthy body weight reduces the blood pressure of both hypertensive and normotensive people. The indirect benefits of a health body weight are well known. The negative effects of weight loss are primarily the frustrations associated with attaining and maintaining a healthy weight. The costs associated with weight loss programs were not measured in the studies reviewed.

RECOMMENDATIONS

(1) It is recommended that health care professionals determine weight (in kilograms), height (in metres) and BMI for all adults. (2) To reduce blood pressure in the population at large, it is recommended that Canadians attain and maintain a healthy BMI (20-25). (3) All overweight hypertensive patients (BMI greater than 25) should be advised to reduce their weight.

VALIDATION

These recommendations are similar to those of the World Hypertension League, the National High Blood Pressure Education Program Working Group on Primary Prevention of Hypertension, the Canadian Hypertension Society and the Canadian Coalition for High Blood Pressure Prevention and Control. They have not been clinically tested.

SPONSORS

The Canadian Hypertension Society, the Canadian Coalition for High Blood Pressure Prevention and Control, the Laboratory Centre for Disease Control at Health Canada, and the Heart and Stroke Foundation of Canada.

Myosin crossbridge configurations in equilibrium states of vertebrate skeletal muscle. Heads swing axially or turn upside-down between resting and rigor

The positions and orientations of the myosin heads in relaxed, active, rigor and S1-labelled fish muscle are being determined by analysis both of electron micrographs and of low-angle X-ray diffraction patterns. The X-ray analysis of resting muscle makes use of the head shape defined from the study of S1 crystals, with variable head configurational parameters being used on each of the three different 3-fold symmetric 14.3 nm-spaced 'crowns' of myosin heads within the 42.9 nm axial repeat of the myosin filaments. Diffraction patterns were stripped using CCP13 fibre diffraction software. Searches and optimisation were carried out using simulated annealing and local refinement procedures to give a 'best fit' relaxed structure with a crystallographic R-factor of about 4%. It had heads oriented all the same way up (i.e. with similar rotations around their own long axes) on the myosin filament, but with a small range of axial tilts. Head configuration in rigor fish muscle is being determined by X-ray diffraction and electron microscopy of normal rigor muscle and of skinned muscle soaked with extrinsic myosin S1. Computed 3-D reconstructions of acto-S1 using X-ray amplitudes and phases from electron microscopy are informative and help to analyse the X-ray diffraction data that extend axially to about 1 nm resolution. An ambiguity is the axial direction of the observed resting myosin head array relative to the known polarity of the actin filaments. One polarity would give little axial displacement (2-3 nm) between opposite ends of the resting and rigor heads, and in this case the heads would need to rotate around their own long axes by about 115 degrees to make a rigor attachment. The other (preferred) filament polarity would provide considerable axial swinging (14-15 nm) between the two states. We are attempting to define the absolute polarity of the resting muscle myosin head array using electron microscopy and image processing either of cryo-sections or of replicas from shadowed, freeze-fractured, rapidly frozen fish muscle fibres.

The structure of the acto-myosin subfragment 1 complex: results of searches using data from electron microscopy and x-ray crystallography

Surmises of how myosin subfragment 1 (S1) interacts with actin filaments in muscle contraction rest upon knowing the relative arrangement of the two proteins. Although there exist crystallographic structures for both S1 and actin, as well as electron microscopy data for the acto-S1 complex (AS1), modeling of this arrangement has so far only been done "by eye." Here we report fitted AS1 structures obtained using a quantitative method that is both more objective and makes more complete use of the data. Using undistorted crystallographic results, the best-fit AS1 structure shows significant differences from that obtained by visual fitting. The best fit is produced using the F-actin model of Holmes et al. [Holmes, K. C., Popp, D., Gebhard, W. & Kabsch, W. (1990) Nature (London) 347, 44-49]. S1 residues at the AS1 interface are now found at a higher radius as well as being translated axially and rotated azimuthally. Fits using S1 plus loops missing from the crystal structure were achieved using a homology search method to predict loop structures. These improved fits favor an arrangement in which the loop at the 50- to 20-kDa domain junction of S1 is located near the N terminus of actin. Rigid-body movements of the lower 50-kDa domain, which further improve the fit, produce closure of the large 50-kDa domain cleft and bring conserved residues in the lower 50-kDa domain into an apparently appropriate orientation for close interaction with actin. This finding supports the idea that binding of ATP to AS1 at the end of the ATPase cycle disrupts the actin binding site by changing the conformation of the 50-kDa cleft of S1.

Pre-operative staging of gastro-oesophageal junction carcinoma: comparison of endoscopic ultrasound and computed tomography

Fifteen patients with carcinoma of the gastro-oesophageal junction were pre-operatively staged with endoscopic ultrasound (EUS) and computed tomography (CT). The accuracy of tumour and nodal staging using both modalities was compared to the final histological staging of the resected specimens. In staging depth of tumour growth, EUS was significantly more accurate (87% of lesions correctly staged) than CT (40% correctly staged). In staging nodal involvement, EUS was again significantly more accurate (73% correctly staged) than CT (33%). Two-thirds of the lesions were traversable with the endoscopic probe, but most of the nontraversed lesions were correctly staged on EUS. In this study, CT has performed poorly as a staging modality for carcinoma at the gastro-oesophageal junction. Other studies have shown CT to be less accurate at this location than at other oesophageal sites. The orientation of the gastro-oesophageal junction, lack of surrounding fat planes, proximity of adjacent organs and patient motion contribute to the poor staging performance of CT at this location. In contrast, EUS has been an accurate staging modality at the gastro-oesophageal junction in this study and compares well with other studies evaluating EUS in the more proximal oesophagus. Endoscopic ultrasound is therefore a necessary modality if accurate pre-operative staging of gastro-oesophageal junction carcinoma is to be achieved.

Surgery for severe constipation: the use of radioisotope transit scan and barium evacuation proctography in patient selection

Nineteen women aged 19-64 years (median 38) with intractable constipation were assessed by Indium-111 DTPA colonic transit scan and barium evacuation proctogram. Patients were classified as having an isolated (I) or predominant disorder of colonic transit (II), a mixed disorder of colonic transit and rectal evacuation (III), a predominant disorder of rectal evacuation (IV) or normal colorectal emptying (V). Twelve patients fell into categories I and II and were considered suitable for surgery. Three responded to further vigorous aperient therapy and nine (32-55 years, median 38) underwent subtotal colectomy with ileorectal anastomosis at the level of the sacral promontory. Two patients required re-operation for suspected anastomotic leak. One patient required readmission on two occasions for small bowel obstruction. Follow up has been 2-21 months (median 16). Eight of the nine patients no longer take oral aperients. Eight patients have a satisfactory stool frequency of 2-8 per 24 h; the other patient has an ileostomy and incapacitating postprandial abdominal pain. Abdominal pain is troublesome in two other patients. Two patients require antidiarrhoeal therapy but none experience faecal incontinence. In severely constipated patients with a proven disorder of colonic transit but normal or near normal rectal evacuation subtotal colectomy provides excellent symptomatic relief.

From the Canadian Dietetic Association. Concept of dietetic practice and framework for undergraduate education for the 21st century

Rapid change and marked diversity are expected to characterize the 21st century. If dietitians are to serve as change facilitators in this environment they will have to demonstrate greater flexibility and creativity, practise critical analysis and problem solving and employ creative thinking. Although provision of quality nutrition care will remain the unique contribution of dietitians, practitioners in the future will require a greater understanding of the impact of social, economic and political systems on food availability and food consumption and, in turn, health and well-being. Critical to the future practice of dietetics will be a greater understanding of research methodology, computer technology, quality improvement processes and risk management, principles governing learning and behaviour, personnel management and organizational behaviour, family and group dynamics, interpersonal communication and their application to dietetic practice. The Canadian Dietetic Association recently adopted a framework for the development of baccalaureate programs in dietetics designed to enable the dietetic practitioner to continue to make a unique contribution in the 21st century. The framework allows individual institutions the freedom and flexibility to plan programs that are compatible with their philosophy and organizational structure. In addition, it is predicted on the principle that a career in dietetics entails a lifetime commitment to education, of which the baccalaureate program is only the beginning.

Immunogenicity and safety of Haemophilus influenzae type b-tetanus protein conjugate vaccine alone or mixed with diphtheria-tetanus-pertussis vaccine in infants

Haemophilus capsular polysaccharide-tetanus toxoid conjugate (PRP-T) and diphtheria-tetanus-pertussis (DTP) vaccines were administered in a single syringe (group 1) or separate syringes (group 2) to 284 infants at 2, 4, and 6 months of age. Group 1 infants had a slightly greater incidence of local reactions. Systemic reactions were similar. The geometric mean titers of polyribosylribitol phosphate (PRP) serum antibody concentrations after the third dose of PRP-T vaccine were 4.8 and 4.3 micrograms/ml for groups 1 and 2, respectively. Antibody responses to DTP antigens were also similar. The immunogenicity and safety of the PRP-T and DTP vaccines are equivalent when the vaccines are administered in separate syringes or the same syringe to infants.

Combining electron microscopy and X-ray crystallography data to study the structure of F-actin and its implications for thin-filament regulation in muscle

The convergence of structures, all determined by independent global searches and subsequent refinement on different electron microscopy data sets, with the X-ray fiber diffraction results strongly suggests that we now have the approximately correct structure for F-actin. This consensus structure will now provide a reliable, well-defined platform upon which to study the structure and function of proteins bound to actin. Among these are capping proteins, such as severin and gelsolin, contractile proteins, such as myosin and its subfragments, and proteins involved in regulation, such as troponin and tropomyosin.

Cefpodoxime proxetil vs. penicillin V in pediatric streptococcal pharyngitis/tonsillitis

This multicenter, randomized, parallel treatment, observer-blinded study was designed to evaluate the safety and efficacy of cefpodoxime proxetil (5 mg/kg twice daily for 10 days) compared with penicillin V (13.4 mg/kg three times daily for 10 days) for treatment of Group A streptococcal pharyngitis and tonsillitis in pediatric patients. Clinical and microbiologic results were evaluated before therapy, during therapy (Study Days 3 to 5), at the end of therapy (Study Days 14 to 18) and at long term follow-up (Study Days 30 to 32). Both drugs were well-tolerated in 578 patients evaluable for safety. Mild gastrointestinal complaints were noted in 6.7% of 386 cefpodoxime-treated patients and in 5.2% of 192 penicillin-treated patients. In 413 patients evaluable for efficacy, both treatment regimens resulted in comparably favorable clinical outcome; cure rates were 83.8% for 275 cefpodoxime-treated patients and 77.5% for 138 penicillin-treated patients. However, eradication of S. pyogenes at end of therapy was significantly higher with cefpodoxime (93.1%) than with penicillin (81.2%) (P < 0.01). Cefpodoxime proxetil provides an effective alternative to penicillin V for the treatment of streptococcal pharyngitis and tonsillitis.

The impact of the Healthiest Babies Possible Program on maternal diet and pregnancy outcome in underweight and overweight clients

The Healthiest Babies Possible Program (HBP) is a prenatal intervention program for the City of Toronto and is designed to reduce the incidence of low birth weight babies. This study was undertaken to assess the impact of the HBP on dietary change and birth outcome for underweight and overweight expectant mothers. Dietary change was measured by the use of food scores applied to 24-hour dietary recalls throughout the pregnancy. Three recalls collected during the early stage of the program were selected to represent early interventions; three of the results collected during the latter stage of the program represent the late stage of intervention. Birth outcome was determined by weight gain and infant birth weight. For both groups, food scores improved throughout the early intervention period and the improvements were sustained through the remainder of the program. During pregnancy the underweight women gained more weight than the overweight women but delivered infants with lower birth weights.

Sunscreens block the induction of epidermal ornithine decarboxylase by ultraviolet-B radiation: a new way of evaluating sunscreen efficacy in vivo

Two proprietary sunscreen preparations containing para-aminobenzoic acid and sulisobenzone, respectively, were tested for their ability to block the induction of ornithine decarboxylase by medium wavelength ultraviolet radiation (UV-B) in the epidermis of the hairless mouse. Both preparations were effective, the sunscreen treated animals requiring more radiation for ornithine decarboxylase induction. The UV dose-dependent gradients were reduced by a mean factor of 7.35 (sulisobenzone) and 15 (PABA). These figures correlate well with other in vivo sunscreen assays. This new method provides a simple and reproducible way of evaluating sunscreens in vivo.

Structure of myosin subfragment 1 from low-angle X-ray scattering

The X-ray scattering pattern produced by a solution of myosin subfragment 1 has been measured to a resolution (Bragg spacing) of 2 nm. We find that for subfragment 1 (S1) prepared by limited papain digestion in the presence of ethylenediaminetetraacetate the radius of gyration is 3.28 +/- 0.06 nm, the volume is 151 +/- 6 nm3, the surface area is 330 +/- 15 nm2, and the length of the maximum chord is 12.0 +/- 1.0 nm. The theoretical scattering patterns from several objects of uniform electron density have been calculated and compared with the observed scattering produced by S1. The recent three-dimensional electron micrograph reconstruction of S1-decorated actin by J. Seymour and E. O'Brien (private communication) generated the calculated pattern that best fit the observed scattering. This fit strongly suggests that this reconstruction resembles subfragment 1. The good correspondence between an S1 structure derived when S1 is attached to actin and a study of free S1 in solution strongly suggests that binding to actin does not grossly distort the shape of S1. This is consistent with the notion that S1 changes its orientation on actin, rather than its shape, in order to generate the contractile force in muscle.

Treatment of HBsAg-positive chronic active hepatitis with human fibroblast interferon

Two patients with HBsAg positive chronic active hepatitis have been treated with human fibroblast interferon 10(7) units daily for two weeks. Before treatment, both patients had high levels of hepatitis B surface antigen, core antibody, and DNA-binding antibody in the blood and one patient had a fourfold rise in serum AST. During treatment there was a striking fall in the core antibody titre and also in the DNA-binding antibody, which has been maintained for several months subsequently; in one patient the initially high AST level fell to normal. No significant adverse effects occurred, and these observations should encourage further trials of fibroblasts interferon in hepatitis B.

Time-dependent fluorescence depolarization and lifetime studies of myosin subfragment-one in the presence of nucleotide and actin

Time-dependent fluorescence depolarization and lifetime studies have been made on myosin subfragment 1 to obtain information about mobility changes and dye environment changes when different nucleotides are added. Data are reported for static and actively hydrolyzing systems containing G- and F-actin. Preliminary data indicate that myosin labeled with the fluorophore 1, 5 IAEDANS and treated with DTT preserves its actin-activated Vmax. S1 prepared in this manner gives lifetime changes which are nearly identical for all systems studied. S1 labeling without DTT addition gives a pattern of lifetimes similar, though not identical to ESR work. Either type of labeling produces no observable change in the polarization decay, and we set an upper limit of 15% length change for the elongate S1. An unusually long fluorescence decay lifetime for the S1-Mg++ ATP-G-actin system is found which may indicate a new acto-S1 state stabilized by G-actin. The method for obtaining the bound fraction of S1's in the presence of actin is presented and applied to the S1-F-actin-Mg++ ATP system. Qualitative agreement is obtained with other methods.