Racial differences in measures of glycemia in the Vitamin D and Type 2 Diabetes (D2d) Study: a secondary analysis of a randomized trial

INTRODUCTION

Understanding how race may influence the association between A1c and glycemia can improve diabetes screening. We sought to determine whether, for a given A1c level, glucose levels during an oral glucose tolerance test (OGTT) differed by race.

RESEARCH DESIGN AND METHODS

From data collected at 22 US clinical sites, we conducted a cross-sectional study of concurrently measured A1c and OGTT and observational longitudinal follow-up of the subset with high-risk pre-diabetes. Numerical integration methods were used to calculate area under the glycemic curve (AUCglu) during OGTT and least squares regression model to estimate A1c for a given AUCglu by race, controlling for potential confounders.

RESULTS

1016 black, 2658 white, and 193 Asian persons at risk of diabetes were included in cross-sectional analysis. Of these, 2154 with high-risk pre-diabetes were followed for 2.5 years. For a given A1c level, AUCglu was lower in black versus white participants. After adjustment for potential confounders, A1c levels for a given AUCglu quintile were 0.15-0.20 and 0.02-0.19 percentage points higher in black and Asian compared with white participants, respectively (p<0.05). In longitudinal analyses, black participants were more likely to be diagnosed with diabetes by A1c than white participants (28% vs 10%, respectively; p<0.01). Black and Asian participants were less likely to be diagnosed by fasting glucose than white participants (16% vs 15% vs 37%, respectively; p<0.05). Black participants with A1c levels in the lower-level quintiles had greater increase in A1c over time compared with white participants.

CONCLUSIONS

Use of additional testing beyond A1c to screen for diabetes may better stratify diabetes risk in the diverse US population.

A Specific Thromboxane Receptor Blocking Drug, AH23848, Reduces Platelet Deposition on Vascular Grafts in Man

The antithrombotic effect of a specific thromboxane A2 receptor blocking drug, AH23848, on radio-labelled platelet deposition in mature Dacron aorto-bifemoral grafts has been evaluated in patients. Thirty patients were randomly allocated to AH23848 70 mg, aspirin 300 mg plus dipyridamole 75 mg or placebo 8-hourly for 9 days. AH23848 inhibited platelet aggregarion induced by the thromboxane ,A2 mimetic U-46619; no such effect was observed with aspirin plus dipyridamole. 111In-platelet uptake was measured as the thrombogenicity index (TI) which is a measure of the daily rate of accumulation of platelets by the graft. The mean (s.e. mean) value of 0.193 (0.029) on placebo was significantly reduced to 0.115 (0.022) by AH23848 (p <0.05) but only to 0.175 (0.028) by aspirin plus dipyridamole. There was no difference in mean platelet life span between the three treatment groups. The pronounced antithrombotic effect of AH23848 implicates thromboxane ,A2 in the process of platelet deposition in arterial prostheses and demonstrates the considerable promise of thromboxane receptor blocking drugs as antithrombotic therapy.

Intrahepatic Kinetics of lndium-111-Labelled Platelets

The intrahepatic kinetics of 111indium-labelled platelets have been studied using dynamic gamma camera scintigraphy immediately following injection. Platelets labelled in saline with mIn-oxine or 111In-acetylacetonate underwent rapidly reversible hepatic sequestration, indicating that they were “activated”. Platelets labelled in plasma with 111In-tropolonate, however, did not display this phenomenon. On the assumption that plasma-labelled platelets display a normal initial bio-distribution, mean intrahepatic platelet transit time, as a factor of the transit time of 99m-Tc labelled red cells, was 1.45 ± SE 0.12 (n = 6), implying the normal presence of a small intrahepatic platelet pool. Unlike the liver, transit through the spleen was not sensitive to the labelling medium; thus the mean intrasplenic transit time of plasma-labelled platelets was 9.3 ± SE 0.7 min (n = 10), and of saline-labelled platelets 9.5 ± SE 0.3 min (n = 8).

The Effects of Thromboxane Antagonism on the Transit Time of Platelets Through the Spleen

The spleen is well-known as a site for platelet pooling, although the mechanisms controlling intrasplenic platelet transit are essentially unknown. We tested the possibility that thromboxane A2 might be involved in this control by measuring intrasplenic platelet transit time in 10 subjects receiving a specific thromboxane A2 receptor antagonist (AH23848B; 70 mg; Glaxo Group Research Ltd), in 10 receiving aspirin (300 mg) plus dipyridamole (75 mg), and in 9 receiving placebo. All doses were administered 3 times daily commencing 4 days prior to transit time measurement.

Mean intrasplenic platelet transit time was measured by monitoring the kinetics of equilibration of 111In radiolabelled platelets between blood and spleen following intravenous injection. There was no difference between the mean transit time in the 3 groups of subjects, lending no support to the hypothesis that thromboxane A2 is involved in the control of platelet traffic through the spleen.

[Current dilemmas on the transmission of hepatitis E virus]

Immunocompromised patients are especially at risk for developing chronic hepatitis E virus (HEV) infection, which may result in progressive liver disease and cirrhosis. In addition, treatment of chronic HEV infection in these patients often includes dose reduction of immunosuppressive therapy and this may lead to severe flare-ups of the underlying condition or even rejection of transplant material. Therefore prevention of HEV transmission is being more and more recognised as an essential step to stop increasing HEV seroprevalence. The Dutch National Institute for Public Health and the Environment (RIVM) has recently warned immunocompromised patients following haematopoietic stem cell and solid organ transplantations for the risk of infection by HEV through eating of contaminated products from pig meat. Furthermore, the Dutch blood bank recently decided to start screening all blood products for HEV to prevent iatrogenic transmission of HEV. We describe two patients with HEV infection and discuss risk of infection for immunocompromised patients, transmission routes and the importance of prevention of iatrogenic transfusion related transmission.

Relationships of body habitus and SUV indices with signal-to-noise ratio of hepatic (18)F-FDG PET

OBJECTIVE

Tissue accumulation of (18)F-FDG is quantified as standardised uptake value (SUV), which may be expressed as the voxel maximum (SUVmax) or mean (SUVmean). SUVmax/SUVmean may be a marker of hepatic steatosis, while the coefficient of variation (CV) of SUV may be a marker of hepatic fat distribution heterogeneity (HFDH). Alternatively, they may reflect low signal-to-noise ratio ('noise') in obese persons in whom hepatic steatosis is common. The study aim was to compare the impact of body size on noise versus SUV and CT density (CTD).

METHODS

Dynamic PET was performed (30×1min frames) following FDG injection in 60 patients undergoing routine PET/CT. Hepatic FDG clearance was measured using Patlak-Rutland graphical analysis with abdominal aorta as input. Noise was quantified as the standard deviation (SD) of the plot residuals (ignoring the first 2 frames), normalised to the intercept (NRMSD). SUVmax, SUVmean and CTD were measured from 60min whole body PET/CT. CV of SUV and SD of CTD were quantified in 28/60 patients using texture analysis.

RESULTS

NRMSD correlated with weight (r=0.49; p<0.0001) and BMI (r=0.48; p=0.0001). SUVmax, SUVmean, SUVmax/SUVmean, CV of SUV, CTD, and SD of CTD all correlated strongly with weight and BMI (p<0.0001). However, they correlated weakly with NRMSD, the strongest being SUVmax (r=0.34; p=0.008) and SD of CTD (r=0.42; n=28; p=0.026).

CONCLUSIONS

Noise is increased in overweight/obese persons but has little effect on SUV indices, CTD and their variabilities. SUVmax/SUVmean and CV of SUV are therefore, to some extent, markers of hepatic steatosis and HFDH, respectively.

The appropriate whole-body index on which to base standardized uptake value in 2-deoxy-2-[(18)F]fludeoxyglucose PET

OBJECTIVE

Tissue uptake of 2-deoxy-2-fluorine-18 fludeoxyglucose ((18)F-FDG) is routinely quantified as standardized uptake value (SUV), which in general is the fraction (F) of administered activity per millilitre of tissue multiplied by an index of body size, usually weight (W), i.e. F/ml × W = SUV or F/ml = SUV × (1/W). Other indices have been suggested as preferable to W, especially lean body mass (LBM) and body surface area (BSA). The second equation mentioned above shows that the reciprocal of the ideal index should correlate closely with F/ml and give a regression line through the origin. The purpose of this study was to determine which of these three indices best meets these criteria.

METHODS

Data were evaluated from 49 males and 51 females undergoing routine (18)F-FDG positron emission tomography/CT. A 3 cm diameter region of interest was drawn over the liver and F/ml recorded. LBM and BSA were estimated from height and weight.

RESULTS

Based on all patients, the reciprocals of the three indices gave similar correlation coefficients with F/ml, but only 1/LBM gave regressions close to the origin. Intercepts were significantly higher for females for 1/W and 1/BSA, consistent with females having more body fat, but there was no significant difference with 1/LBM.

CONCLUSION

LBM is the best index on which to base SUV because adipose tissue accumulates less (18)F-FDG than other soft tissues.

ADVANCES IN KNOWLEDGE

The value of this study lies in its use of a novel, more rational approach than previously to confirm that SUV should be based on LBM.

Adjuvant taxanes and the development of breast cancer-related arm lymphoedema

BACKGROUND

Despite affecting approximately one-quarter of all patients undergoing axillary lymph node dissection, the pathophysiology of breast cancer-related lymphoedema (BCRL) remains poorly understood. More extensive locoregional treatment and higher body mass index have long been identified as major risk factors. This study aimed to identify risk factors for BCRL with a specific focus on the potential impact of chemotherapy on the risk of BCRL.

METHODS

This was a retrospective analysis of a cohort of consecutive patients with breast cancer treated at a major London regional teaching hospital between 1 January 2010 and 31 December 2012. All patients had node-positive disease and underwent axillary lymph node dissection. Data regarding tumour-, patient- and treatment-related characteristics were collected prospectively. The diagnosis of BCRL was based on both subjective and objective criteria. Multivariable Cox proportional hazards regression was used to assess the association between treatment and risk of BCRL.

RESULTS

Some 27.1 per cent of all patients (74 of 273) developed BCRL over the study period. Administration of taxanes showed a strong association with the development of BCRL, as 52 (33.5 per cent) of 155 patients who received taxanes developed BCRL. Multivariable Cox regression analysis demonstrated that patients who received taxanes were nearly three times more likely to develop BCRL than patients who had no chemotherapy (hazard ratio 2.82, 95 per cent c.i. 1.31 to 6.06). No such increase was observed when taxanes were administered in the neoadjuvant setting.

CONCLUSION

The present findings suggest that adjuvant taxanes play a key role in the development of BCRL after surgery. This may support the use of taxanes in a neoadjuvant rather than adjuvant setting.

Global abnormalities in lymphatic function following systemic therapy in patients with breast cancer

Background

Breast cancer-related lymphoedema (BCRL) is a result of interaction between several pathophysiological processes, and is not simply a ‘stopcock’ effect resulting from removal of axillary lymph nodes. The aim of this study was to test the hypothesis that there is a constitutional ‘global’ lymphatic dysfunction in patients who develop BCRL.

Methods

Lower-limb lymphoscintigraphy was performed in 30 women who had undergone axillary lymph node dissection at least 3 years previously, of whom 15 had BCRL and 15 did not. No patient had any clinical abnormality of the lower limb. The control group comprised 24 women with no history of cancer or lower-limb lymphoedema. 99mTc-Nanocoll was injected subcutaneously into the first webspace of each foot, followed by whole-body imaging. Scans were reported as abnormal if there was delay in lymph transport or rerouting through skin or deep system. Quantification was expressed as the percentage injected activity accumulating in ilioinguinal nodes.

Results

Mean(s.d.) ilioinguinal nodal accumulation at 150 min was significantly lower in women with BCRL than in those without (2·7(2·5) versus 5·9(4·8) per cent respectively; P = 0·006). Abnormal findings on lower-limb lymphoscintigraphy were observed in 17 of the 30 patients: ten of the 15 women who had BCRL and seven of the 15 who did not. None of the 24 control subjects had abnormal scan findings.

Conclusion

Women with BCRL had reduced lower-limb lymph drainage, supporting the hypothesis of a predisposition to BCRL. A surprisingly high proportion of patients with breast cancer also demonstrated lymphatic dysfunction, despite clinically normal lower limbs. Possible explanations could be a systemic effect of breast cancer or its treatment, or an unidentified association between breast cancer and lymphatic dysfunction. Registration number: ISRCTN84866416 (http://www.isrctn.com).

A constitutional predisposition to breast cancer-related lymphoedema and effect of axillary lymph node surgery on forearm muscle lymph flow

AIM

The aims of this prospective study were (a) to examine the relationship between pre-operative muscle lymph flow and the predisposition to BCRL in women treated by axillary nodal surgery for breast cancer; and (b) to test the 'stopcock' hypothesis that axillary lymph node surgery impairs forearm lymph flow in the short term.

METHODS

(99m)Tc-nanocoll was injected intramuscularly into both forearms of women undergoing surgery for breast cancer. Lymphatic clearance rate constant, k, representing lymph flow per unit interstitial fluid volume, was measured as the fractional disappearance rate of radioactivity from the depot site by gamma camera imaging. Axillary lymph node activity was calculated as percentage injected activity. BCRL was assessed by clinical examination and upper limb perometry.

RESULTS

Of 38 pre-operative women, 33 attended at 8 ± 6 weeks post-operatively and 31 at 58 ± 9 weeks post-operatively. Seven patients (18%) developed BCRL. Prior to surgery the BCRL-destined patients had a higher mean k (0.0962 ± 0.034%/min) than non-BCRL patients (0.0830 ± 0.019%/min) (p = 0.10, unpaired t test). Post-operative k values were not significantly different from pre-operative, in either the ipsilateral (operated) or contralateral limb. Also, post-operative k values did not differ significantly between both upper limbs. Furthermore, there was no significant difference between pre- and post-operative axillary activity.

CONCLUSION

Patients who develop BCRL have high lymph flow pre-surgery, which may predispose them to lymphatic overload and failure. Axillary lymph node surgery has no early, measurable effect on forearm muscle lymph flow despite surgical disruption of routes of lymph drainage.

Determination of extracellular fluid volume in healthy and azotemic cats

BACKGROUND

Methods for determining extracellular fluid volume (ECFV) are important clinically for cats. Bromide dilution has been studied in cats to estimate ECFV. Markers of GFR also distribute in ECFV and can be used for its measurement.

HYPOTHESIS/OBJECTIVES

The primary objective was to develop a method of determining ECFV from iohexol clearance in cats and evaluate agreement with that determined using bromide dilution. Additional objectives were to compare ECFV between azotemic and nonazotemic cats and evaluate appropriate methods of standardizing ECFV.

ANIMALS

Client-owned cats with varying renal function.

METHODS

Validation of ECFV determined from slope-intercept iohexol clearance was performed in 18 healthy nonazotemic cats. ECFV was then determined using the validated method and bromide dilution and agreement assessed. Appropriateness of standardization to body weight (BW) and body surface area (BSA) was evaluated.

RESULTS

Extracellular fluid volume determined from slope-intercept iohexol clearance and bromide dilution was 0.84 ± 0.32 L and 0.85 ± 0.19 L (mean ± SD), respectively. There were wide limits of agreement between the methods (-0.58 to 0.54 L) and therefore, agreement was considered to be poor. ECFV did not differ significantly between azotemic and nonazotemic cats (P = .177). BSA was found to be the best method for standardizing ECFV measurement in cats.

CONCLUSIONS AND CLINICAL IMPORTANCE

This study developed a method for determining ECFV from slope-intercept iohexol clearance which provides simultaneous assessment of renal function and an estimate of ECFV. ECFV does not differ between azotemic and nonazotemic cats, which suggests fluid volume loss or overload is not an important clinical feature in cats with mild chronic kidney disease.

Change in Nox4 expression is accompanied by changes in myogenic marker expression in differentiating C2C12 myoblasts

Myoblast differentiation is mediated by a cascade of changes in gene expression including transcription factors such as myogenin. Subsequent to myoblast differentiation, there is an increase in expression of the transmembrane protein NADPH oxidase (Nox). Nox is one of the primary factors for the generation of reactive oxygen species (ROS) in myogenic (C2C12) cells. Recently, ROS have been shown to be important regulators of several intracellular signaling pathways, and the full extent of their regulatory roles is yet to be discovered. In the present study, qRT PCR analysis demonstrated that Nox4 isoform is primarily expressed in differentiating C2C12 cells and contributes to the generation of ROS in C2C12 myoblast during differentiation. Over-expression and silencing of Nox4 expression during myoblast differentiation was accompanied by a reduction in intracellular ROS concentrations and an alteration in the expression patterns of Myf5, Pax7, MyoD1, and myogenin. This modulation was found to be associated with ERK1/2 phosphorylation. In both over-expression and reduced expression of Nox4, we found significant reductions in ERK1/2 phosphorylation. This indicates that cellular differentiation may be affected by Nox4-mediated endogenous ROS generation. These data suggest a new opportunity to study the temporal expression of Nox4 in the generation of ROS accompanying changes in myogenic differentiation.

A qualitative and quantitative assessment of the impact of three processing algorithms with halving of study count statistics in myocardial perfusion imaging: filtered backprojection, maximal likelihood expectation maximisation and ordered subset expectation maximisation with resolution recovery

INTRODUCTION

Ordered subset expectation maximisation with depth-dependent resolution recovery (OSEM-RR) is a processing algorithm reported to improve images with halved tracer activity in myocardial perfusion scintigraphy (MPS) compared to filtered backprojection (FBP) using conventional activities. OSEM-RR has not yet been compared with maximal likelihood expectation maximisation (MLEM).

METHODS

39 patients undergoing MPS and two anthropomorphic phantoms (one with, one without an inferior wall insert) had full-time (FT) and half-time (HT) SPECT datasets acquired simultaneously and processed by FBP, MLEM and OSEM-RR. Two experienced reporters scored images of all clinical studies (n=234) for conspicuity of a perfusion defect, with results being compared using Wilcoxon paired and Kappa tests. A quantitative assessment based on mean segmental pixel counts taken from numbers automatically displayed over the 20 segments of Cedars Sinai Autoquant QPS image were compared using Pearson's correlation and Bland Altman analysis.

RESULTS

A small but consistent superior concurrence between FT and HT datasets for OSEM-RR compared to FBP and MLEM was observed for both qualitative and quantitative analyses. OSEM-RR resulted in better definition of the inferior wall defect on the phantom study.

CONCLUSION

OSEM-RR appears superior to both FBP and MLEM in terms of handling reduced count statistics.

Estimation of lean body mass in children

BACKGROUND

In adults, dosages of some anaesthetic agents are based on lean body mass (LBM) rather than body weight. Our aim was to derive an equation for estimating LBM in children.

METHODS

Patients comprised three groups: prospective kidney transplant donors from two separate centres (centres 1 and 3) and children referred to a further centre (centre 2) for the routine clinical measurement of glomerular filtration rate (GFR). GFR and extracellular fluid volume (ECV) were measured using Cr-51-EDTA. LBM was directly estimated (eLBM) in adults using an equation based on height and weight. ECV in children was estimated (eECV) from another equation based on height and weight, converted to eLBM using the relationship between eLBM and ECV determined in the adults from centre 1 and then compared with adult data from centre 3.

RESULTS

In children, the ratio of eECV to ECV was 1.04 (SD 0.18). In centre 1, eLBM (kg) was 3.81 (SD 0.55) times greater than ECV (litres) in men (n=50) and 3.77 (0.77) times greater in women (n=51). eLBM in children was therefore derived by multiplying eECV by 3.8. In children, eLBM showed a close linear correlation with measured ECV (eLBM=3.50ECV+2.0; R(2)=0.857), similar to adults (eLBM=2.82ECV+14.5; R(2)=0.582). In all groups, eLBM/weight correlated inversely with weight.

CONCLUSIONS

In terms of the relationships between eLBM, ECV, and weight, children are similar to adults. Therefore, drug dosage in children should also be based on eLBM rather than weight.

Imaging of multidrug resistance in cancer

Primary intrinsic and/or acquired multidrug resistance (MDR) is the main obstacle to successful cancer treatment. Functional molecular imaging of MDR in cancer using single photon or positron emitters may be helpful to identify multidrug-resistant tumours and predict not only those patients who are resistant to treatment, with a clinically unfavourable prognosis, but also those who are susceptible to the development of drug toxicity or even certain tumours . Variations in the mdr1 gene product may directly affect the therapeutic effectiveness, and single nucleotide polymorphisms for the mdr1 gene may be associated with altered oral bioavailability of MDR1 substrates, drug resistance, and a susceptibility to some human diseases. The challenge of translating the concept of MDR modulation in vivo involves a complex cellular interplay between both malignant and normal cells. Integration and correlation of functional single photon emission tomography or positron emission tomography imaging findings with mdr1 genotype and clinical data may contribute to efficient management by selecting cancer patients with the appropriate molecular phenotype for maximal individual therapeutic benefit, as well as those who are non-responders. This review describes a role for functional imaging of classical mechanisms of MDR with an emphasis on readily available [^99mTc]MIBI scintigraphy. MIBI scintigraphy has been shown to be a non-invasive cost-effective in vivo assay of ATP-binding cassette transporters associated with MDR in cancer, including P-glycoprotein, multidrug-resistant protein 1 and breast cancer resistant protein. New imaging agents for molecular targets such as vascular endothelial growth factor and HER2 receptors, may potentially be combined with MDR imaging substrates to more accurately predict the therapeutic response to anticancer drugs, guiding individualised treatment while minimising the economic health costs of ineffective therapy in an era of personalised medicine.

Sympathetic nerve damage as a potential cause of lymphoedema after axillary dissection for breast cancer

BACKGROUND

The physiological disturbances leading to lymphoedema after breast cancer surgery are poorly understood. Damage to sympathetic nerves during axillary lymph node dissection (ALND), leading to increased capillary fluid filtration, was investigated as a possible contributory factor.

METHODS

The integrity of the upper limb sympathetic nervous system was tested in 36 patients before, and 3 and 12 months after ALND. Forearm vascular resistance (FVR), calculated from forearm blood flow and mean systemic arterial pressure, was measured before and after exposure to lower-body negative pressure. Forearm venous compliance was measured using (99m)Tc-labelled autologous erythrocytes and radionuclide plethysmography before and after cold water immersion of the feet.

RESULTS

There were clear changes in FVR and venous compliance in response to sympathetic stimulation but no differences attributable to surgery or between the nine patients who developed lymphoedema and the 27 who did not; nor were there differences between the two arms. There was a trend towards lower preoperative FVR in patients who developed lymphoedema.

CONCLUSION

Lymphoedema is not the result of sympathetic nerve damage sustained during ALND. Preoperative FVR may help predict who will get lymphoedema following this surgery.

Cassie-Baxter to Wenzel state wetting transition: scaling of the front velocity

We experimentally study the dynamics of water in the Cassie-Baxter state to Wenzel state transition on surfaces decorated with assemblies of micrometer-size square pillars arranged on a square lattice. The transition on the micro-patterned superhydrophobic polymer surfaces is followed with a high-speed camera. Detailed analysis of the movement of the liquid during this transition reveals the wetting front velocity dependence on the geometry and material properties. We show that a decrease in gap size as well as an increase in pillar height and intrinsic material hydrophobicity result in a lower front velocity. Scaling arguments based on balancing surface forces and viscous dissipation allow us to derive a relation with which we can rescale all experimentally measured front velocities, obtained for various pattern geometries and materials, on one single curve.

Obesity does not accelerate the decline in glomerular filtration rate associated with advancing age

Obesity has been suggested as a risk factor for chronic kidney disease. However, it has also been suggested that the association between obesity and impaired glomerular filtration rate (GFR) arises from the invalid use of body surface area (BSA) for scaling. This study assesses the effect of obesity on GFR by comparing the age-dependent decline in obese (body mass index (BMI) >30 kg/m(2); n=149) and non-obese patients (n=589), aged >30 years, referred for measurement of GFR (Cr-51-EDTA and three blood samples). GFR was scaled to a BSA of 1.73 m(2) (GFR/BSA) and extracellular fluid volume of 13 l (GFR/ECV), both corrected for the one-compartment assumption. When non-obese patients were categorized into 10-year age brackets (from 31 to >70), GFR/BSA and GFR/ECV declined from 92 ml per min per 1.73 m(2) and 95 ml per min per 13 l, respectively, at 31-40 years to 58 and 59 at >70. The declines in obese patients were similar with corresponding values of 88 ml per min per 1.73 m(2) and 97 ml per min per 13 l at 31-40 and 57 and 59 at >70 years. Linear regression analysis of non-categorized data from age 40 years showed rates of decline slightly slower in the obese (0.82 vs 0.95 ml per min per 1.73 m(2) per year and 0.87 vs 1.02 ml per min per 13 l per year). No effect of obesity on renal function was shown. Scaling to BSA did not distort the results.

Reliability of the MDRD method for estimating glomerular filtration rate in relation to gender, body mass index and extracellular fluid volume

BACKGROUND

The accuracy of estimating glomerular filtration rate from plasma creatinine (eGFR) has been questioned but it is unclear how much covert error in several reference methods that have been used has contributed to this perceived inaccuracy. The aim of the study was to evaluate eGFR in comparison with a second 'gold standard' to test the performance of the primary gold standard and to examine the influence of patient demographics (age, body mass index (BMI), extracellular fluid volume (ECV) and gender).

DESIGN

Non-fasting multisample GFR and ECV were measured in 80 subjects simultaneously and independently with Cr-51-EDTA (GFR(EDTA)) and iohexol (GFR(iohexol)). Percentage bias and imprecision in the prediction of, and disagreement with, GFR(EDTA) were compared between eGFR and GFR(iohexol). Another simplified method for measuring GFR, the slope-only method ((SO)GFR), was also evaluated against multisample GFR (measured with the opposing indicator). Accuracies were assessed in all subjects and across age, BMI and ECV boundaries of 65 y, 29 kg m(-2) and 14 L.

RESULTS

eGFR was less precise than GFR(iohexol) (imprecisions of 22.3% and 12.9%; P < 0.01). The precision of (SO)GFR was intermediate between eGFR and GFR(iohexol). Both GFR(iohexol) and eGFR were less precise in the elderly, the obese and men, but minimally influenced by ECV. (SO)GFR was minimally influenced by subject demographics.

CONCLUSION

Although eGFR does not predict GFR (based on a primary gold standard) as accurately as a second gold standard, a significant component of its poor performance is the result of inaccuracy in the primary gold standard. (SO)GFR measured with Cr-51-EDTA is superior to eGFR.

Pyoderma Gangraenosum, a Rare, but Potentially Fatal Complication in Paediatric Oncology Patients

Pyoderma gangraenosum (PG) is a serious chronic, ulcerative skin disorder afflicting both adults and children. As PG is often associated with systemic diseases (>50%) such as inflammatory bowel disease, rheumatoid arthritis or haematological disorders, it requires a multidisciplinary approach. This disorder is not commonly reported in paediatrics; therefore children with PG represent a particularly difficult diagnostic challenge. Clinical diagnosis is often delayed and PG is only considered after eliminating other causes of cutaneous ulcers. We report a 4-year-old boy with secondary myelodysplastic syndrome following treatment for acute lymphoblastic leukaemia who presented with a massive inflammatory, ulcerative proliferation of the lower lip which was diagnosed as PG. We have reviewed the literature with reference to diagnostic criteria and treatment options of this disorder that is particularly rare in childhood.

The clearance kinetics of autologous RhD-positive erythrocytes coated ex vivo with novel recombinant and monoclonal anti-D antibodies

Anti-D is given routinely to pregnant RhD-negative women to prevent haemolytic disease of the fetus and newborn. To overcome the potential drawbacks associated with plasma-derived products, monoclonal and recombinant forms of anti-D have been developed. The ability of two such antibodies, BRAD-3/5 monoclonal anti-D IgG (MAD) and rBRAD-3/5 recombinant anti-D IgG (RAD), to clear RhD-positive erythrocytes from the circulation was compared using a dual radiolabelling technique. Six RhD-positive males received autologous erythrocytes radiolabelled with (99m)Tc and (51)Cr and coated ex vivo with MAD and RAD. Blood samples were collected up to 1 h following intravenous injection, and percentage dose of radioactivity in the samples determined. Three different levels of coating were used on three separate occasions. No significant differences between MAD and RAD were observed in the initial clearance rate constant at any dose level. The log[activity]-time clearance plots were curved, showing a reduction in the clearance rate constant with time. This reduction was more marked for RAD than for MAD. The results support a dynamic model for the clearance of antibody-coated erythrocytes that may have wider relevance for the therapeutic use of antibodies.

Human lymphatic pumping measured in healthy and lymphoedematous arms by lymphatic congestion lymphoscintigraphy

Axillary surgery for breast cancer partially obstructs lymph outflow from the arm, chronically raising the lymphatic smooth muscle afterload. This may lead to pump failure, as in hypertensive cardiac failure, and could explain features of breast cancer treatment-related lymphoedema (BCRL) such as its delayed onset. A new method was developed to measure human lymphatic contractility non-invasively and test the hypothesis of contractile impairment. 99mTc-human IgG (Tc-HIG), injected into the hand dermis, drained into the arm lymphatic system which was imaged using a gamma-camera. Lymph transit time from hand to axilla, ttransit, was 9.6+/-7.2 min (mean+/-s.d.) (velocity 8.9 cm min(-1)) in seven normal subjects. To assess lymphatic contractility, a sphygmomanometer cuff around the upper arm was inflated to 60 mmHg (Pcuff) before 99mTc-HIG injection and maintained for>>ttransit. When Pcuff exceeded the maximum pressure generated by the lymphatic pump (Ppump), radiolabelled lymph was held up at the distal cuff border. Pcuff was then lowered in 10 mmHg steps until 99mTc-HIG began to flow under the cuff to the axilla, indicating Ppump>or=Pcuff. In 16 normal subjects Ppump was 39+/-14 mmHg. Ppump was 38% lower in 16 women with BCRL, namely 24+/-19 mmHg (P=0.014, Student's unpaired t test), and correlated negatively with the degree of swelling (12-56%). Blood radiolabel accumulation proved an unreliable measure of lymphatic pump function. Lymphatic congestion lymphoscintigraphy thus provided a quantitative measure of human lymphatic contractility without surgical cut-down, and the results supported the hypothesis of lymphatic pump failure in BCRL.

Lymphatic transfer studies with immunoglobulin scintigraphy after axillary surgery

AIMS

The study objective was to investigate the effects of axillary lymph node clearance surgery on the function and morphology of the lymphatic system of the upper limb in women with breast cancer.

METHODS

Nineteen women were studied before and 3 months after surgery. Fifteen were studied again 12 months after surgery. On each occasion, scintigraphy following intradermal hand webspace injection of Tc-99m-human polyclonal immunoglobulin was performed to include the affected upper limb and torso.

RESULTS

There was considerable functional variability in response to surgery. Seven patients subsequently developed breast cancer-related lymphedema (BCRL). Neither lymph re-routing (defined as a change in lymph vessel morphology or definition) nor linear velocity of protein transit up the arm was associated with the development of BCRL. Blood pool activity, judged from visual inspection of the cardiac blood pool on the whole body images, was earlier and more marked 3 and 12 months after surgery than before. The count rate (per 100 pixels/MBq injected activity), measured in a cardiac region of interest, was significantly higher after surgery than before, was higher in patients who developed BCRL and, in the patient population as a whole, correlated positively with arm swelling.

CONCLUSION

The consequences of axillary lymph node clearance were variable, unexpected and largely persistent. An increased rate of access of intradermally injected protein into the blood pool is significantly associated with BCRL.

A simple processing method allowing comparison of renal enhancing volumes derived from standard portal venous phase contrast-enhanced multidetector CT images to derive a CT estimate of differential renal function with equivalent results to nuclear medicine quantification

As iodinated contrast medium is cleared by glomerular filtration, it should be possible to apply the same principles utilized in radionuclide studies to derive differential renal function by comparison of enhancing renal volumes derived from contrast enhanced multidetector CT (CEMDCT). Having established a technique iteratively which appeared successful, a retrospective study was performed using 25 consecutive patients with a wide range of urological conditions who had undergone both CEMDCT, including the renal area in the portal venous phase, and nuclear medicine (NM) assessment of renal function with no urological intervention between the studies. Proprietary volume software was used to quantify the volume and attenuation of each kidney, the products of which (after subtraction of soft tissue attenuation derived from a region of interest over psoas) gave right and left enhancing renal volumes. The contribution by each kidney as a percentage of total renal enhancing tissue was derived. Comparison with NM studies resulted in excellent correlation of relative renal function by CEMDCT and NM assessments having a regression of near unity and a Pearson's correlation coefficient of 0.96. Bland Altman and Passing Bablock tests confirmed good agreement between the two methods with no bias. This is a simple, practicable processing technique using standard portal venous phase CEMDCT images to quantify differential function. This technique may allow a one-stop CT assessment of both anatomy and function.

Maternal hemoglobin concentration during pregnancy and risk of infant leukaemia: a children's oncology group study

In contrast to the positive association found in three studies between maternal anaemia during pregnancy and childhood leukaemia, no such association was found in infant leukaemia (odds ratio 0.85, 95% confidence interval 0.53–1.37).

A brief history of cell labelling

The term cell labelling is usually used in the context of labelled leukocytes for imaging inflammation and labelled platelets for imaging thrombosis. Erythrocyte labelling for in vitro measurements of red cell life span, in vivo measurements of splenic red cell pooling, radionuclide ventriculography and imaging sites of bleeding has developed rather separately and has a different history. Labelled platelets and leukocytes were originally developed for cell kinetic studies. Since the current-day applications of labelled platelets and leukocytes depend on a clear understanding of cell kinetics, these classical studies are important and relevant to the history of cell labelling.

Polycystic kidneys and renal transplant imaging

Renal transplantation is an ever-increasing procedure. Baseline DTPA renography is routinely performed in these patients in many centers to assess transplant perfusion and function. This report describes 2 cases of unusual appearance at renography resulting from the native polycystic kidneys.

Impairment of lymph drainage in subfascial compartment of forearm in breast cancer-related lymphedema

BACKGROUND

In arm lymphedema secondary to axillary surgery and radiotherapy (breast cancer-related lymphedema), the swelling is largely epifascial and lymph flow per unit epifascial volume is impaired. The subfascial muscle compartment is not measurably swollen despite the iatrogenic damage to its axillary drainage pathway, but this could be due to its low compliance. Our aim was to test the hypothesis that subfascial lymph drainage too is impaired.

METHODS AND RESULTS

Quantitative lymphoscintigraphy was used to measure the removal rate constant (local lymph flow per unit distribution volume) for technetium-99m-human immunoglobulin G injected intramuscularly in the forearms of nine women with unilateral lymphedema. The removal rate constant was on average 31% lower in the ipsilateral swollen forearm than in the contralateral forearm (swollen arm: -0.096+/-0.041% min(-1), contralateral arm: -0.138+/-0.037% min(-1); mean+/-SD, p = 0.037). The decrease in subfascial rate constant correlated strongly with increase in arm volume (r = -0.88, p = 0.002), even though the swelling is mainly epifascial. There was no convincing evidence of dermal backflow.

CONCLUSIONS

Lymph flow in the subfascial muscle compartment is decreased in breast cancer-related lymphedema. The correlation between impairment of subfascial drainage and epifascial arm swelling could be because both depend on the severity of axillary damage, or because loss of function in subfascial lymphatics impairs drainage from the epifascial to the subfascial system.

Radioguided occult lesion localisation (ROLL) and sentinel node biopsy for impalpable invasive breast cancer

AIM

The aim of this study was to simplify the technique of ROLL and sentinel node biopsy without compromising tumour excision and sentinel node biopsy.

METHODS

Twenty patients with impalpable primary invasive breast carcinoma underwent an injection of 99mTc-nanocolloid mixed with radiographic contrast medium Iohexol into the centre of the lesion under ultrasound or stereotactic guidance pre-operatively. No guidewire localisation was performed. Under general anaesthesia, a periareolar intradermal/subcutaneous injection of patent blue-V dye was performed. The sentinel node was identified by blue-stained lymphatics and node and a hot spot on the gamma probe. Surgical excision of the primary tumour was then carried out using the gamma probe.

RESULTS

In eight of 20 cases an immediate re-excision was carried out and on histological assessment, all 20 patients were clear of invasive disease at the margins. In two patients, in situ disease was present at the margins and a further re-excision was therefore performed. The sentinel node was identified in all cases. In all, five of 20 patients were node positive on routine HE staining. In a further two patients, tumour cells were identified by immunohistochemistry with CAM5.2 antibody. Completion axillary clearance in six patients confirmed that the sentinel node was the only positive node.

CONCLUSIONS

This modification of the previously described ROLL technique is feasible and safe and does not compromise tumour excision or sentinel node detection.

Variation in lymphatic function may predispose to development of breast cancer-related lymphoedema

AIMS

Breast cancer-related lymphoedema (BCRL) remains a common complication of breast cancer treatment. Many features of this condition remain poorly understood, such as why only approximately 25% of women are affected after similar treatment, and the phenomenon of 'sparing', in which regions of an otherwise swollen arm, most commonly the hand, remain unaffected. This study uses dual-isotope lymphoscintigraphy, involving measurement of rate of clearance of radiolabelled protein from a subcutaneous depot and subsequent appearance in blood, to quantify alterations in lymphatic function in women with BCRL, and to further investigate differences between those in whom the hand is involved with swelling and those in whom it is spared.

METHODS

Participants received a depot injection of human immunoglobulin G in the dorsum of both hands, labeled with technetium-99m on one side and indium-111 on the other. Rates of clearance from the depot and appearance in venous blood were measured at regular intervals over a 3 h period.

RESULTS

A total of 18 women with a history of BCRL were studied. Significant reductions in both depot clearance and venous appearance were observed in the affected arm compared with the unaffected contralateral control. On sub-group analysis, significant differences were also observed between swollen and spared hand groups, both for the affected and unaffected contralateral arm.

DISCUSSION

This study, as well as confirming impaired lymphatic function in arms affected by BCRL, also shows underlying variation in lymphatic function in the unaffected contralateral arm, between those with and without hand sparing. This raises the possibility that the risk of developing BCRL may be, in part, pre-determined.

Cerebral neutrophil recruitment, histology, and outcome in acute ischemic stroke: an imaging-based study

BACKGROUND AND PURPOSE

Evidence now exists for a pathogenic role for neutrophils in acute cerebral ischemia. We have studied the patterns and temporal profile of cerebral neutrophil recruitment to areas of acute ischemic stroke (IS) and have attempted to correlate this with neurological status and outcome.

METHODS

Patients with cortical middle cerebral artery (MCA) IS were recruited within 24 hours of clinical onset. Neutrophil recruitment was studied using indium-111 (111In) troponolate-labeled neutrophils, planar imaging, and single-photon emission computed tomography (SPECT). Volume of brain infarction was calculated from concurrent computed tomography (CT). Hematoxylin and eosin sections were obtained postmortem (n=2). Outcome was measured using Barthel, Rankin, and National Institute of Health Stroke (NIHSS) scales.

RESULTS

Fifteen patients were studied. Significant 111In-neutrophil recruitment to ipsilateral hemisphere, as measured by asymmetry index (AI), was demonstrated within 24 hours of onset in 9 patients; this response was heterogenous between patients and on repeated measurement attenuated over time. Histologically, recruitment was confirmed within intravascular, intramural, and intraparenchymal compartments. Interindividual heterogeneity in neutrophil response did not correlate with infarct volume or outcome. In an exploratory analysis, neutrophil accumulation appeared to correlate significantly with infarct expansion (Spearman rho=0.66; P=0.03, n=12).

CONCLUSIONS

Neutrophils recruit to areas of ischemic brain within 24 hours of symptom onset. This recruitment attenuates over time and is confirmed histologically. While neutrophil accumulation may be associated with either the magnitude or the rate of infarct growth, these results require confirmation in future studies.

Tissue-to-Blood Transport of Radiolabelled Immunoglobulin Injected into the Web Spaces of the Hands of Normal Subjects and Patients with Breast Cancer-Related Lymphoedema

AIM

The ability to return interstitial protein to central blood is key to the defence against oedema. The aim of this study was to quantify this ability by measuring the rate at which radiolabelled human immunoglobulin (HIgG) accumulated in blood following injection into the subcutis of the hand in normal volunteers and in patients with breast cancer-related lymphoedema (BCRL).

METHODS

A total of 37 control subjects (healthy normal volunteers or breast cancer patients prior to treatment) and 18 women with BCRL were studied with dual-isotope lymphoscintigraphy. Each received bilateral subcutaneous depot injection in the dorsal web space of HIgG labelled with Tc-99m on one side and In-111 on the other. Activities remaining at the depot and accumulating in blood were measured at regular intervals for 3 h. Clearance from the depot was exponential and expressed as the rate constant k(depot) (min(-1)). Accumulation in blood was essentially linear and, using an estimate of blood volume based on height and weight, was expressed as the linear constant b(blood) (% administered activity x min(-1)). The time axis intercept of this linear fit was recorded as an index of the minimum time to arrival of radioprotein in blood. The efficiency with which radioprotein that has left the depot (extra-depot activity) is transported into blood [tissue-to-blood (T-B) transport] was quantified (1) as the quotient b(blood)/k(depot), and (2) as a function of time after injection by comparing the total amount of radioprotein in blood at any time with the total amount of radioprotein that was no longer in the depot at the same time.

RESULTS

Tc-99m-HIgG and In-111-HIgG behaved similarly and are interchangeable. At all times between 60 and 180 min in controls, about 50% of protein that had left the depot was present in blood. T-B transport was reduced to about 20% in BCRL arms in which the hand was involved in swelling (p < 0.001 versus controls), but remained unchanged in patients in whom the hand was spared. The minimum time to arrival of radioprotein in blood was not reduced in BCRL; on the contrary, there appeared to be a small proportion of injected activity that arrived rapidly in blood in BCRL patients but not in controls.

CONCLUSION

We conclude that T-B transport is only impaired in BCRL when radioprotein is injected into swollen tissue. Significant quantities of radioprotein may escape from the arm via local access to blood. Individual variation in this capacity may explain the regional sparing observed in BCRL.

Evidence of thymic reconstitution after highly active antiretroviral therapy in HIV-1 infection

OBJECTIVES

We aimed to provide evidence of thymic reconstitution after highly active antiretroviral therapy (HAART) in HIV-1 infected patients and to correlate this with the restoration of peripheral naïve T cells.

METHODS

Positron emission tomography (PET) enables definitive evidence of thymic activity, indicating functional potential. In this case study, a single patient who initiated HAART demonstrated reconstitution of the naïve T-cell pool and underwent thymic PET scans at baseline and 2 and 6 months following initiation of therapy. Two patients who failed to demonstrate such reconstitution acted as controls. These patients (mean age 27 years) had chronic HIV infection with low CD4 T-cell counts (mean 82, range 9-160 cells/microL blood). Increased function of the thymus visualized by PET was correlated with phenotypic changes in CD4 and CD8 T cells in the periphery measured by flow cytometry, and with numbers of recent thymic emigrants measured by quantification of the numbers of T-cell receptor excision circles (TRECs) in peripheral cells.

RESULTS

In one patient, clear correlations could be drawn between visible activity within the thymus, as measured by increased [F18]fluorodeoxyglucose (FDG) uptake, and regeneration of naïve CD4 (CD45RA/CD62L) T cells, increased numbers of CD4 T cells, controlled viraemia and increased numbers of recent thymic emigrants. A second patient displayed no increase in peripheral CD4 count and no increase in thymic activity. The third patient elected to stop therapy following the 2-month time point.

CONCLUSIONS

The use of PET suggests that thymic activity may increase after HAART, indicating that the thymus has the potential to be functional even in HIV-1 infected persons with low CD4 T-cell counts.

The kinetic basis of glomerular filtration rate measurement and new concepts of indexation to body size

As measurement of glomerular filtration rate (GFR) is now generally the responsibility of departments of nuclear medicine, it is important for nuclear medicine physicians and scientists to understand the pharmacokinetics of the indicators and radiotracers that are used, generally known as filtration markers. The single-injection, non-steady state technique is almost universally used, departments varying in how many blood samples are taken: rarely multisample clearance, which does not assume a single compartment of tracer distribution, commonly clearance based on a limited number of blood samples between 2 and 4 h after injection, which assumes a single compartment of distribution, and often a single sample at a defined time point. The volume of distribution, V(d), of a filtration marker is close to extracellular fluid volume (ECFV). GFR and ECFV are both overestimated by the assumption of a single compartment by amounts that are functions of the rate of plasma clearance, Z. Residence time, T, of tracer in its V(d) is equal to V(d) divided by Z. Z and T can both be measured from a multisample clearance curve, whereupon V(d) is the product of Z and T. GFR is usually indexed to patient size by expressing it in relation to body surface area (BSA), which in turn is calculated from an equation based on the patient's height and weight. An equation in common use was described by Haycock et al. and is BSA=0.024265 x weight(0.5378) x height(0.3964). An alternative indexation variable is ECFV. GFR per unit ECFV is close to the rate constant, alpha(3), of the terminal exponential of the plasma clearance curve. It is in fact slightly higher than this rate constant by an amount that is a function of the rate constant itself. The discrepancy between GFR/ECFV and alpha(3) arises from the development of a concentration gradient between interstitial fluid and plasma, which in turn produces an extrarenal veno-arterial gradient throughout the body. Indexing GFR to ECFV not only has physiological attractions (especially in children) but is technically simple because it requires measurement only of alpha(3) (slope-only technique). A disadvantage, however, is a lack of robustness in comparison with the conventional slope/intercept method, which measures tracer dilution as well as alpha(3). Nevertheless, the advantages of indexation to ECFV can still be exploited by changing the constants of an equation of the Haycock type so that the equation becomes a predictor of ECFV rather than BSA. A recently described equation is ECFV=0.02154 x weight(0.6469) x height(0.7236). Indexation to ECFV abolishes differences that arise between children and adults when GFR is indexed to BSA.

Cognitive Control Mechanisms Revealed by ERP and fMRI: Evidence from Repeated Task-Switching

We investigated the extent to which a common neural mechanism is involved in task set-switching and response withholding, factors that are frequently confounded in taskswitching and go/no-go paradigms. Subjects' brain activity was measured using event-related electrical potentials (ERPs) and event-related functional MRI (fMRI) neuroimaging in separate studies using the same cognitive paradigm. Subjects made compatible left/right keypress responses to left/right arrow stimuli of 1000 msec duration; they switched every two trials between responding at stimulus onset (GO task—green arrows) and stimulus offset (WAIT task—red arrows). Withholding an immediate response (WAIT vs. GO) elicited an enhancement of the frontal N2 ERP and lateral PFC activation of the right hemisphere, both previously associated with the “nogo” response, but only on switch trials. Task-switching (switch vs. nonswitch) was associated with frontal N2 amplification and right hemisphere ventrolateral PFC activation, but only for the WAIT task. The anterior cingulate cortex (ACC) was the only brain region to be activated for both types of task switch, but this activation was located more rostrally for the WAIT than for the GO switch trials. We conclude that the frontal N2 ERP and lateral PFC activation are not markers for withholding an immediate response or switching tasks per se, but are associated with switching into a response-suppression mode. Different regions within the ACC may be involved in two processes integral to task-switching: processing response conflict (rostral ACC) and overcoming prior response suppression (caudal ACC).

A pilot study of event-related functional magnetic resonance imaging of monitored wrist movements in patients with partial recovery

BACKGROUND AND PURPOSE

Previous functional imaging studies of motor recovery after stroke have investigated cerebral activation during periods of repetitive, often complex, movement. This article reports the use of an event-related approach to study activation associated with isolated simple movements (wrist extension). This allows investigation of the pattern of the motor response and corresponding brain activation on a trial-by-trial basis. Patients with partial recovery can be assessed, and allowance can be made for abnormalities in the shape of hemodynamic responses.

METHODS

Functional MRI at 3 T was performed during a series of isolated, near-isometric wrist extension movements. A visual tracking procedure was used to elicit forces of 10% and 20% of maximum voluntary contraction. Force output from both wrists was monitored continuously. A voxel-wise procedure was used to fit the optimum hemodynamic response functions in each case.

RESULTS

Three chronic stage patients with partial recovery were successfully scanned and compared with 8 healthy controls. The patients showed well-lateralized motor responses but inaccurate control of force. During movement of the paretic wrist, we observed excessive activation of the ipsilateral primary motor cortex and increased relative activation of the supplementary motor area compared with movement of the nonparetic side. In the primary motor area, hemodynamic responses peaked more quickly on the ipsilateral side in 2 patients for movements of the paretic hand, whereas controls showed the opposite trend.

CONCLUSIONS

An event-related approach can be used to study the relationship between motor responses and cerebral activation in patients with partial recovery. These preliminary findings suggest that excessive activation in ipsilateral motor cortex and secondary motor areas remains evident under these tightly controlled conditions and cannot be ascribed to mirror movements or abnormalities in the timing of the blood oxygen level-dependent (BOLD) response. However, close monitoring of motor responses also makes evident continuing impairment in motor skill, which makes comparison with activation in normal controls difficult.

Polyethylene glycol in the design of tumor-targetting radiolabelled macromolecules -- lessons from liposomes and monoclonal antibodies

Radiolabelled macromolecules such as liposomes and monoclonal antibodies (Mab) are attractive agents for tumour-targetting studies. In addition to their potential diagnostic role, they can also provide vital information on the targetting capacity of therapeutic agents. Certainly in the case of liposome development, this ability to track the pharmacokinetics and biodistribution of the agents in a non-invasive fashion has assisted the design and application of therapeutic liposomal agents. A significant limitation of unmodified liposomes and Mab is their tendency to be cleared rapidly from the circulation. The use of polyethylene glycol (PEG) in the formulation of these agents has the capacity to alter their biological behaviour in such a way as to improve their ability to target tumours. In this paper we review the data relating to the use of PEG-modified liposomes and Mab in the context of nuclear medicine studies.

Scintigraphy using a technetium 99m-labelled anti-E-selectin Fab fragment in rheumatoid arthritis

OBJECTIVE

We previously described a novel radiolabelled monoclonal antibody (1.2B6), which reacts with porcine E-selectin, for targeting activated endothelium as a means of imaging inflammatory disorders, and presented initial clinical work based on (111)In-labelled antibody. The aim of the present study was to evaluate a Fab fragment of 1.2B6 labelled with (99m)Tc in patients with rheumatoid arthritis (RA) by comparison with (i) (111)In-labelled 1.2B6 F(ab')(2) and (ii) conventional bone scanning.

METHODS

(99m)Tc-1.2B6-Fab ( approximately 440 MBq) and (111)In-1.2B6-F(ab')(2) ( approximately 27 MBq) were compared in 10 patients using a double-isotope protocol. Images were obtained 4 and 20-24 h after injection. Two normal volunteers were also imaged. In a separate group of 16 patients, (99m)Tc-1.2B6-Fab and (99m)Tc-oxidronate ((99m)Tc-HDP) ( approximately 740 MBq) were compared on the basis of visual and semi-quantitative analysis of joint uptake (joint/soft tissue ratios) 4 h after injection. The respective biodistributions and blood clearances of the two 1.2B6 fragments were also compared.

RESULTS

Image contrast was slightly better with (99m)Tc-Fab at 4 h but equal for the two tracers at 24 h. Diagnostic accuracy, taking joint tenderness or swelling as the clinical endpoint, was 76% for both fragments at 24 h. Plasma clearance of (99m)Tc-Fab was faster than that of (111)In-F(ab')(2) (t(1/2) 142 vs 421 min; P<0.0001). (99m)Tc-Fab appeared somewhat unstable in vivo, as shown by activity in the thyroid gland and bowel. The diagnostic accuracy of (99m)Tc-Fab was 88%, higher than that of (99m)Tc-HDP (57%) as a result of the low specificity of the latter in RA. Receiver operating characteristic (ROC) curve analysis using joint/soft tissue ratios as a variable cut-off showed that (99m)Tc-Fab discriminates better than (99m)Tc-HDP between actively inflamed and silent joints (Z=4.72; P<0.0001). No uptake of (99m)Tc-Fab was observed by inactive or normal joints, whereas (99m)Tc-HDP was taken up by all joints to a variable degree, making the decision as to whether a particular joint is actively involved or chronically damaged very difficult.

CONCLUSION

(99m)Tc-anti-E-selectin-Fab scintigraphy can be used successfully to image synovitis with better specificity than (99m)Tc-HDP bone scanning. The advantages over (111)In-1.2B6-F(ab')(2) are easier availability of the radionuclide, improved physical properties and optimal imaging 4 h after injection.

Phase II study of pegylated liposomal doxorubicin (Caelyx) as induction chemotherapy for patients with squamous cell cancer of the head and neck

A phase II trial of pegylated liposomal doxorubicin (Caelyx) as induction chemotherapy was conducted in 20 patients with treatment-naïve squamous cell cancer of the head and neck (SCCHN). 10 patients received two cycles of Caelyx (40 mg/m(2)) every 3 weeks before starting radical radiotherapy (RT). Subsequently, consecutive groups of 3 patients received a third escalating dose of Caelyx (10, 15 and 20 mg/m(2)) 3 days before RT. 9 of 18 (50%, 95% confidence intervals (CI): 26-74%) evaluable patients responded to Caelyx, with 11 responses in 26 (42%, 95% CI: 24-62%) evaluable sites (three complete responses (12%), eight partial responses (31%)). There was no grade 3/4 haematological, mucosal or cardiac toxicity. Nausea and vomiting were minimal. There were no drug-related RT delays. Local RT-induced toxicity was not increased. Caelyx has significant activity against SCCHN and warrants further investigation in this disease. In view of its tumour targeting properties and activity at moderate doses, it may be useful in concomitant chemoradiotherapy strategies for SCCHN.

Cerebral activation during a simple force production task: changes in the time course of the haemodynamic response

An event-related paradigm was used to investigate the fMRI signal from the primary motor cortex (M1) and the supplementary motor area (SMA) during isolated isometric wrist extension at five different force levels. There was only a weak trend towards increased area of activation with increased force output, but there was a force-related increase in percentage change of signal within voxels in M1 (Kendall Tc = 0.48, p < 0.01), which may indicate control of force output by variation of neural firing rate. In SMA there was a correlation between peak force output and time-to-peak of the haemodynamic response in SMA (Kendall Tc = 0.74, p < 0.0001). This unexpected finding of a task-related change in the shape of the haemodynamic response within a single brain area requires further investigation. It may indicate a slower rise time at lower perfusion rates, or may be the result of inhibitory processes in motor control.

Differences in lymph drainage between swollen and non-swollen regions in arms with breast-cancer-related lymphoedema

Recent research indicates that the pathophysiology of breast-cancer-related lymphoedema (BCRL) is more complex than simple axillary lymphatic obstruction as a result of the cancer treatment. Uneven distribution of swelling (involvement of the mid-arm region is common, but the hand is often spared) is puzzling. Our aim was to test the hypothesis that local differences in lymphatic drainage contribute to the regionality of the oedema. Using lymphoscintigraphy, we measured the removal rate constant, k (representing local lymph flow per unit distribution volume, VD), for 99mTc-labelled human immunoglobulin G in the oedematous proximal forearm, and in the hand (finger web) in women in whom the hand was unaffected. Tracer was injected subcutaneously, and the depot plus the rest of the arm was monitored with a gamma-radiation camera for up to 6 h. VD was assessed from image width. Contralateral arms served as controls. k was 25% lower in oedematous forearm tissue than in the control arm (BCRL, -0.070+/-0.026% x min(-1); control, -0.093+/-0.028% x min(-1); mean+/-S.D.; P=0.012) and VD was greater. In the non-oedematous hand of the BCRL arm, k was 18% higher than in the control hand (BCRL, -0.110+/-0.027% x min(-1); control, -0.095+/-0.028% x min(-1); P=0.057) and 59% higher than forearm k on the BCRL side (P=0.0014). VD did not differ between the hands. Images of the BCRL arm following hand injection showed diffuse activity in the superficial tissues, sometimes extending almost to the shoulder. A possible interpretation is that the hand is spared in some patients because local lymph flow is increased and diverted along collateral dermal routes. The results support the hypothesis that regional differences in surviving lymphatic function contribute to the distribution of swelling.

Detection of pelvic lymph node metastases in gynecologic malignancy: a comparison of CT, MR imaging, and positron emission tomography

OBJECTIVE

Accurate assessment of lymph node status before treatment is critical in the treatment of gynecologic cancers because the 5-year survival and treatment of women is influenced by lymph node involvement. The aims of this study were to investigate the ability of X-ray CT, MR imaging, and (18)F-FDG positron emission tomography (PET) to detect pelvic lymph node metastases by comparing imaging with histopathologic findings after lymph node dissection.

MATERIALS AND METHODS

Eighteen patients with gynecologic cancers were studied by all three imaging methods before surgery. The images were initially reviewed with routine diagnostic conditions and then, subsequently, by two observers who were unaware of the clinical and histopathologic findings of the patients. The nodal sites were split into upper (aortic to common iliac bifurcations) and lower (common iliac bifurcations to inguinal ligament) iliac chains. All observers' results were statistically analyzed with specificity, sensitivity, positive and negative predictive values, Fisher's exact test (individual observers) or chi-square test (combined observers), and Cohen's kappa test.

RESULTS

Eight of 18 patients had lymph node metastases at histology. Findings of all three modalities agreed in full in only one patient. CT correctly revealed 10 node-negative patients, whereas MR imaging was correct in eight of these patients. (18)F-FDG PET correctly depicted one patient with lymph nodes negative for tumor. CT was the most specific imaging modality (97.0%), with MR imaging and PET rendering values of 90.7% and 77.3%, respectively, but sensitivity of all modalities was low (CT, 48.1%; MR imaging, 53.7%; PET, 24.5%). Observer agreement for each modality was good; kappa values among all observers were 0.88 for CT, 0.85 for MR imaging, and 0.72 for PET.

CONCLUSION

CT is the most specific modality for detecting lymph nodes positive for tumor in gynecologic cancers, whereas MR imaging is the most sensitive. The poor results of PET in the pelvis are attributed to urinary (18)F-FDG in the ureters or bladder, which may mask or imitate lymph node metastases.