Prediction of the jugular venous waveform using a model of CSF dynamics

BACKGROUND AND PURPOSE

We have previously reported a model of cerebral hydrodynamics in the form of an equivalent electrical circuit. The aim of this work was to demonstrate that the model could predict venous flow patterns seen in the superior sagittal sinus (SSS), straight sinus (STS), and jugular vein (JV) in normal volunteers.

MATERIALS AND METHODS

An electrical equivalence model of CSF and cerebral blood flow was fitted to measured arterial and CSF data from 16 healthy volunteers. Predictions of the venous outflow waveform derived from the model were compared with measured venous flows in the SSS, STS, and JV.

RESULTS

The model accurately predicted the measured jugular waveform. The measured waveforms from SSS and STS showed a less pronounced and delayed systolic peak compared with the predicted outflow. The fitted bulk model parameters provided relative values that correspond approximately to the impedance of arterial capillaries (1.0), cerebral aqueduct ( approximately 0), venous capillaries ( approximately 0), and arteries (0.01) and for the elastic capacitance of the ventricles (4.11), capillaries ( approximately 0), and veins (271). The elastic capacitance of the major cerebral arteries was large and could not be accurately determined.

CONCLUSIONS

We have confirmed the ability of the model to predict the venous waveforms in healthy persons. The absence of any statistically significant component of the venous waveform not described by the model implies that measurements of venous flow could be used to constrain further the model-fitting process.

Comparison of cerebral blood volume maps generated fromT2* andT1weighted MRI data in intra-axial cerebral tumours

We compared parametric maps, measured values and value distributions of cerebral blood volume (CBV) derived from (1) first pass T1 weighted dynamic contrast-enhanced (DCE) data (T1-CBV) using the recently described leakage profile model and (2) conventional T2* weighted DCE data (T2*-CBV) using a conventional curve fitting technique, in nine patients with intraaxial tumours. Regions of interest were defined around enhancing tumour tissue on matched slices. Median tumour values and conspicuity indexes of CBV from the two techniques were compared, demonstrating good correlation (r = 0.667,p<0.05) in enhancing tumour and no significant difference in conspicuity. Pixel-by-pixel scattergrams of values in normal brain in a representative matched slice were produced for each case, which showed excellent correlation (r = 0.96,p<0.001). Distortion of blood vessels around susceptibility interfaces was evident on T2* CBV but not on T1 CBV maps. Leakage-free T1 CBV maps do not suffer from the susceptibility artifacts seen in T2* CBV maps, although they present comparable biological information.

Clinical features and associated morbidity of scabies in a rural community in Alagoas, Brazil

OBJECTIVE

To describe the clinical characteristics of scabies and the associated morbidity in an impoverished rural community in northeast Brazil.

METHOD

A door-to-door survey was made to examine twice the population of an endemic area; first at the end of the rainy season, and a second time in the dry season 4 months later.

RESULTS

In total, 2005 individuals were examined. The overall prevalence of scabies was 9.8% (95% CI 8.5-11.2). Predilection sites with similar relative frequencies in all age groups were the abdomen (83.7%) and the inguinal area/inner part of the thighs (66.3%). Hands, feet, genitals and the scalp/neck/face were significantly more often affected in children <7 years (all P < 0.03). Fifty-five per cent of the patients showed scabies lesions simultaneously at > or = 12 distinct topographic areas. Papular lesions were most commonly found, followed by papular-crusted lesions. Vesicles were significantly more often observed in children (P = 0.04). Sixty-four per cent of the patients had three or more types of lesions. Local lymphadenopathy was present in 53.6% and superinfection in 36.7% of the cases. The number of topographic areas affected, as well as the proportion of superinfected lesions, was inversely correlated with age (rho = -0.22, P = 0.002 and rho = -0.358, P < 0.05, respectively). The quantity of skin surface infested, the proportion of superinfected lesions and the presence of a superinfected lesion distal to an enlarged lymphnode were predictors of lymphadenopathy. Seventy-two per cent of the patients suffered from sleep disorders, mainly because of itching.

CONCLUSION

Scabies is associated with considerable morbidity in this endemic community. Predilection sites, clinical presentation, quantity of skin surface affected and proportion of secondary infected lesions show a dichotomy between children and adults.

An admittance control scheme for a robotic upper- limb stroke rehabilitation system

This paper presents a control scheme for a dual robot upper-limb stroke rehabilitation system. A model of the human arm is outlined and used to formulate an admittance controller operating in human upper-limb joint space. Initial results are provided together with a discrussion of future work.

DCE-MRI biomarkers in the clinical evaluation of antiangiogenic and vascular disrupting agents

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is now frequently used in early clinical trial assessment of antiangiogenic and vascular disrupting compounds. Evidence of drug efficacy and dose-dependent response has been demonstrated with some angiogenesis inhibitors. This review highlights the critical issues that influence T₁-weighted DCE-MRI data acquisition and analysis, identifies important areas for future development and reviews the clinical trial findings to date.

Quantifying heterogeneity in dynamic contrast-enhanced MRI parameter maps

Simple summary statistics of Dynamic Contrast-Enhanced MRI (DCE-MRI) parameter maps (e.g. the median) neglect the spatial arrangement of parameters, which appears to carry important diagnostic and prognostic information. This paper describes novel statistics that are sensitive to both parameter values and their spatial arrangement. Binary objects are created from 3-D DCE-MRI parameter maps by "extruding" each voxel into a fourth dimension; the extrusion distance is proportional to the voxel's value. The following statistics are then computed on these 4-D binary objects: surface area, volume, surface area to volume ratio, and box counting (fractal) dimension. An experiment using 4 low and 5 high grade gliomas showed significant differences between the two grades for box counting dimension computed for extruded v(e) maps, surface area of extruded K(trans) and v(e) maps and the volume of extruded v(e) maps (all p < 0.05). An experiment using 18 liver metastases imaged before and after treatment with a vascular endothelial growth factor (VEGF) inhibitor showed significant differences for surface area to volume ratio computed for extruded K(trans) and v(e) maps (p = 0.0013 and p = 0.045 respectively).

A survey of mental health nurses' experiences of stalking

Although an increasing amount of literature has appeared in recent years on the subject of stalking, little is known about mental health nurses' (MHNs) experiences of this phenomenon. The aims of the study were to investigate: (1) the incidence of stalking among a sample of MHNs in the UK; (2) who the perpetrators were; (3) the impact of stalking on MHNs; and (4) how MHNs manage their experiences. Employing a survey design, the British version of the Rutgers-Penn clinicians and stalking questionnaire was distributed to a convenience sample of 400 MHNs in the UK. Data were analysed by means of descriptive statistics and McNemar test. The findings reveal that: (1) 50% (n = 56) of MHNs who completed the questionnaire had been stalked; (2) on the whole, victims were female (78.6%) and stalkers males (82.1%); (3) stalkers were from a variety of social groups including mental health service users and MHNs; (4) victims were threatened, followed, physically assaulted and received unwanted communication; (5) MHNs reported a variety of stress-related (psychological and behavioural) responses to their experiences; and (6) employed a range of coping strategies. This study serves to raise awareness of a number of issues surrounding an under-reported phenomenon in mental health nursing and points to the need for further research to explore the reliability and consequences of the findings.

A double-blind randomised trial to evaluate the effect of anastrozole for the treatment of non-toxic multinodular goitre

Multinodular goitre (MNG) is a common clinical finding, particularly in females and is usually asymptomatic. When symptoms occur because of local pressure-related effects the only treatment is surgical involving partial or total thyroidectomy. A number of epidemiological observations and experimental data have suggested that oestrogen aromatase activity may be involved in the pathogenesis of MNG. This study examines the effect of anastrozole, a non-steroidal aromatase inhibitor that inhibits the peripheral conversion of testosterone to oestradiol, in reducing the size of MNG. Thirty-two post-menopausal female patients, median age 63 years (range 42-84) were randomised in a double-blind fashion to receive either anastrozole 1 mg daily or placebo for 3 months. Ultrasonographic measurement of each thyroid lobe and isthmus together with complete biochemical and hormone profiles were performed at the start and end of treatment. There was no significant reduction in the goitre size for patients in the anastrozole group (p = 0.246) or the placebo group (p = 0.418). There were no significant changes in hormone profiles (including throglobulin concentration) within each group between the start and end of the study. We conclude that the use of anastrozole in the treatment of MNG does not appear to have any effect in reducing the size of MNG.

A Study in a Community in Brazil in Which Cutaneous Larva Migrans Is Endemic

BACKGROUND

Cutaneous larva migrans (CLM) is a common but neglected parasitic skin disease in impoverished communities of the developing world.

METHODS

To describe the clinical features and the morbidity associated with CLM, active-case finding was performed during rainy and dry seasons in a rural community in the state of Alagoas, Northeast Brazil.

RESULTS

A total of 62 individuals received a diagnosis for CLM, and among them there were a total of 75 larval tracks. The number of tracks per person ranged from 1 to 3. Children <9 years old were affected significantly more often than other age groups (P<.001). Children had their lesions mainly on the buttocks, genitals, and hands, whereas in older patients, the majority of lesions were located on the feet. Twenty-four percent of the 75 lesions were superinfected. Bacterial superinfection was more common among children. All but 1 patient complained about itching, and 84% of the 62 patients complained about sleep disturbances. Itching was classified as being severe by 61% of patients. Approximately 40% of the 62 patients had attempted to treat their creeping eruption previously. Larvae moved forward 2.7 mm per day. There was a significant correlation between the length of the track and the duration of infestation ( rho =.53; P<.0001).

CONCLUSIONS

CLM is a common parasitic skin disease in this rural community, with different topographic patterns of lesions in children and adults. CLM is associated with considerable morbidity. The length of the track can be used to estimate the duration of infestation.

Impact of antiretroviral choice on hypercholesterolaemia events: the role of the nucleoside reverse transcriptase inhibitor backbone

BACKGROUND

The use of highly active antiretroviral therapy (HAART) has profoundly altered the life expectancy of individuals infected with HIV. Metabolic abnormalities associated with antiretrovirals and cumulative exposure to combination antiretroviral therapy, including dyslipidaemia and insulin resistance, have been linked to an increased risk of myocardial infarction.

METHODS

Longitudinal data from a large prospectively collected clinical database were analysed. All patients who commenced first antiretroviral therapy (ART) [two nucleoside reverse transcriptase inhibitors (NRTIs)+one nonnucleoside reverse transcriptase inhibitor (NNRTI) or one active protease inhibitor (PI)] since 1996 were identified. Patients with elevated cholesterol levels [>5.5 mmol/L (215 mg/dL)] prior to therapy initiation were excluded. Quantitative data were categorized into quartiles and presented stratified by individuals developing abnormal levels of cholesterol during first-line HAART. Event time was defined as time from commencing first-line ART to either development of cholesterol level >6.5 mmol/L (254 mg/dL) or switch of first-line therapy. The Kaplan-Meier product limit survival method was used to estimate time to abnormal cholesterol level, and the chi2 test was used for comparisons between drug classes. Cox's proportional hazards regression analysis was used to identify factors predicting a likelihood of raised cholesterol level.

RESULTS

A total of 1664 patients were included in the study: 57.1% on two NRTIs+one NNRTI, 38.4% on two NRTIs+one PI, and 4.4% on two NRTIs+a boosted PI regimen. Regimens containing stavudine or PIs were associated with a significantly higher event risk and earlier time to event. No differences between efavirenz and nevirapine or between didanosine and lamivudine were observed. In 28 patients exposed to the combination of tenofovir+lamivudine+efavirenz, there were no episodes of elevated cholesterol level.

CONCLUSION

Dyslipidaemia has emerged as an important issue in HIV-infected individuals receiving antiretroviral therapy. This study demonstrates that age at start of therapy, baseline cholesterol level, stavudine use and PI use are all associated with increased risk of hypercholesterolemia on initial therapy. Both NRTI and NNRTI/PI choice influence risk of hypercholesterolaemia.