A method for assessing quality of control from glucose profiles

AIM

As the practice of multiple assessments of glucose concentration throughout the day increases for people with diabetes, there is a need for an assessment of glycaemic control weighted for the clinical risks of both hypoglycaemia and hyperglycaemia.

METHODS

We have developed a methodology to report the degree of risk which a glycaemic profile represents. Fifty diabetes professionals assigned risk values to a range of 40 blood glucose concentrations. Their responses were summarised and a generic function of glycaemic risk was derived. This function was applied to patient glucose profiles to generate an integrated risk score termed the Glycaemic Risk Assessment Diabetes Equation (GRADE). The GRADE score was then reported by use of the mean value and the relative percent contribution to the weighted risk score from the hypoglycaemic, euglycaemic, hyperglycaemic range, respectively, e.g. GRADE (hypoglycaemia%, euglycaemia%, hyperglycaemia%).

RESULTS

The GRADE scores of indicative glucose profiles were as follows: continuous glucose monitoring profile non-diabetic subjects GRADE = 1.1, Type 1 diabetes continuous glucose monitoring GRADE = 8.09 (20%, 8%, 72%), Type 2 diabetes home blood glucose monitoring GRADE = 9.97 (2%, 7%, 91%).

CONCLUSIONS

The GRADE score of a glucose profile summarises the degree of risk associated with a glucose profile. Values < 5 correspond to euglycaemia. The GRADE score is simple to generate from any blood glucose profile and can be used as an adjunct to HbA1c to report the degree of risk associated with glycaemic variability.

A systematic review of cognition in homeless children and adolescents

Objectives The cognitive function of homeless children and adolescents may be overlooked, albeit understandably, when societal interventions focus on their immediate housing needs. Nevertheless, homelessness might be hypothesized to carry many risks for the developing mind and brain. We wanted to discover whether this hypothesis had been tested previously. Design A systematic review to examine whether cognitive impairments were reported in homeless children and adolescents. Setting Objective, systematic review of standard databases, examined by key word searches. Participants Children and adolescents. Main outcome measures Formal assessments of cognition. Results We found that in spite of there being many homeless children in the world, fewer than 2000 have been assessed cognitively and reported in the literature. Yet when compared with those who are domiciled, these children tend to have lower intellectual functioning and decreased academic achievement. Furthermore, adolescents evince cognitive impairments in the contexts of drug, physical, and sexual abuse. Conclusions We suggest that cognitive and mental health screening be incorporated into those intervention programs deployed to facilitate societal reintegration of homeless children and adolescents.

Pancreatic cancer in type 1 and young-onset diabetes: systematic review and meta-analysis

We conducted a systematic review of the risk of pancreatic cancer in people with type I and young-onset diabetes. In three cohort and six case–control studies, the relative risk for pancreatic cancer in people with (vs without) diabetes was 2.00 (95% confidence interval 1.37–3.01) based on 39 cases with diabetes.

Development and validation of stroke risk equation for Hong Kong Chinese patients with type 2 diabetes: the Hong Kong Diabetes Registry

OBJECTIVE

We sought to develop stroke risk equations for Chinese patients with type 2 diabetes in Hong Kong.

RESEARCH DESIGN AND METHODS

A total of 7,209 Hong Kong Chinese type 2 diabetic patients without a history of stroke at baseline were analyzed. The data were randomly and evenly divided into the training subsample and the test subsample. In the training subsample, stepwise Cox models were used to develop the risk equation. Validation of the U.K. Prospective Diabetes Study (UKPDS) stroke risk engine and the current stroke equation was performed in the test dataset. The life-table method was used to check calibration, and the area under the receiver operating characteristic curve (aROC) was used to check discrimination.

RESULTS

A total of 372 patients developed incident stroke during a median of 5.37 years (interquartile range 2.88-7.78) of follow-up. Age, A1C, spot urine albumin-to-creatinine ratio (ACR), and history of coronary heart disease (CHD) were independent predictors. The performance of the UKPDS stroke engine was suboptimal in our cohort. The newly developed risk equation defined by these four predictors had adequate performance in the test subsample. The predicted stroke-free probability by the current equation was within the 95% CI of the observed probability. The aROC was 0.77 for predicting stroke within 5 years. The risk score was computed as follows: 0.0634 x age (years) + 0.0897 x A1C + 0.5314 x log(10) (ACR) (mg/mmol) + 0.5636 x history of CHD (1 if yes). The 5-year stroke probability can be calculated by: 1 - 0.9707(EXP (Risk Score - 4.5674)).

CONCLUSIONS

Although the risk equation performed reasonably well in Chinese type 2 diabetic patients, external validation is required in other populations.

A systematic review of cognition in homeless children and adolescents

Objectives The cognitive function of homeless children and adolescents may be overlooked, albeit understandably, when societal interventions focus on their immediate housing needs. Nevertheless, homelessness might be hypothesized to carry many risks for the developing mind and brain. We wanted to discover whether this hypothesis had been tested previously. Design A systematic review to examine whether cognitive impairments were reported in homeless children and adolescents. Setting Objective, systematic review of standard databases, examined by key word searches. Participants Children and adolescents. Main outcome measures Formal assessments of cognition. Results We found that in spite of there being many homeless children in the world, fewer than 2000 have been assessed cognitively and reported in the literature. Yet when compared with those who are domiciled, these children tend to have lower intellectual functioning and decreased academic achievement. Furthermore, adolescents evince cognitive impairments in the contexts of drug, physical, and sexual abuse. Conclusions We suggest that cognitive and mental health screening be incorporated into those intervention programs deployed to facilitate societal reintegration of homeless children and adolescents.

Fast neutron radiography scanner for the detection of contraband in air cargo containers

There is a growing need to rapidly scan bulk air cargo for contraband such as illicit drugs and explosives. The Commonwealth Science and Industrial Research Organisation (CSIRO) have been working with Australian Customs Service to develop a scanner capable of directly scanning airfreight containers in 1--2 minutes without unpacking. The scanner combines fast neutron and gamma-ray radiography to provide high-resolution images that include information on material composition. A full-scale prototype scanner has been successfully tested in the laboratory and a commercial-scale scanner is due to be installed at Brisbane airport in 2005.

Cost-utility analyses of intensive blood glucose and tight blood pressure control in type 2 diabetes (UKPDS 72)

AIMS/HYPOTHESIS

This study estimated the economic efficiency (1) of intensive blood glucose control and tight blood pressure control in patients with type 2 diabetes who also had hypertension, and (2) of metformin therapy in type 2 diabetic patients who were overweight.

METHODS

We conducted cost-utility analysis based on patient-level data from a randomised clinical controlled trial involving 4,209 patients with newly diagnosed type 2 diabetes conducted in 23 hospital-based clinics in England, Scotland and Northern Ireland as part of the UK Prospective Diabetes Study (UKPDS). Three different policies were evaluated: intensive blood glucose control with sulphonylurea/insulin; intensive blood glucose control with metformin for overweight patients; and tight blood pressure control of hypertensive patients. Incremental cost : effectiveness ratios were calculated based on the net cost of healthcare resources associated with these policies and on effectiveness in terms of quality-adjusted life years gained, estimated over a lifetime from within-trial effects using the UKPDS Outcomes Model.

RESULTS

The incremental cost per quality-adjusted life years gained (in year 2004 UK prices) for intensive blood glucose control was 6,028 UK pounds, and for blood pressure control was 369 UK pounds. Metformin therapy was cost-saving and increased quality-adjusted life expectancy.

CONCLUSIONS/INTERPRETATION

Each of the three policies evaluated has a lower cost per quality-adjusted life year gained than that of many other accepted uses of healthcare resources. The results provide an economic rationale for ensuring that care of patients with type 2 diabetes corresponds at least to the levels of these interventions.

A model to estimate the lifetime health outcomes of patients with type 2 diabetes: the United Kingdom Prospective Diabetes Study (UKPDS) Outcomes Model (UKPDS no. 68)

AIMS/HYPOTHESIS

The aim of this study was to develop a simulation model for type 2 diabetes that can be used to estimate the likely occurrence of major diabetes-related complications over a lifetime, in order to calculate health economic outcomes such as quality-adjusted life expectancy.

METHODS

Equations for forecasting the occurrence of seven diabetes-related complications and death were estimated using data on 3642 patients from the United Kingdom Prospective Diabetes Study (UKPDS). After examining the internal validity, the UKPDS Outcomes Model was used to simulate the mean difference in expected quality-adjusted life years between the UKPDS regimens of intensive and conventional blood glucose control.

RESULTS

The model's forecasts fell within the 95% confidence interval for the occurrence of observed events during the UKPDS follow-up period. When the model was used to simulate event history over patients' lifetimes, those treated with a regimen of conventional glucose control could expect 16.35 undiscounted quality-adjusted life years, and those receiving treatment with intensive glucose control could expect 16.62 quality-adjusted life years, a difference of 0.27 (95% CI: -0.48 to 1.03).

CONCLUSIONS/INTERPRETATIONS

The UKPDS Outcomes Model is able to simulate event histories that closely match observed outcomes in the UKPDS and that can be extrapolated over patients' lifetimes. Its validity in estimating outcomes in other groups of patients, however, remains to be evaluated. The model allows simulation of a range of long-term outcomes, which should assist in informing future economic evaluations of interventions in type 2 diabetes.

Nitrite Formation and Nitrous Oxide Emissions as Affected by Reclaimed Effluent Application

The effect of irrigation with reclaimed effluent (RE) (after secondary treatment) on the mechanisms and rates of nitrite formation, N2O emissions, and N mineralization is not well known. Grumosol (Chromoxerert) soil was incubated for 10 to 14 d with fresh water (FW) and RE treated with 15NO3- and 15NH4+ to provide a better insight on N transformations in RE-irrigated soil. Nitrite levels in RE-irrigated soil were one order of magnitude higher than in FW- irrigated soil and ranged between 15 to 30 mg N kg(-1) soil. Higher levels of NO2- were observed at a moisture content of 60% than at 70% and 40% w/w. Nitrite levels were also higher when RE was applied to a relatively dry Grumosol (20% w/w) than at subsequent applications of RE to soil at 40% w/w. Isotopic labeling indicated that the majority of NO2 was formed via nitrification. The amount of N2O emitted from RE-treated Grumosol was double the amount emitted from FW treatments at 60% w/w. Nitrification was responsible for about 42% of the emissions. The N20 emission from the RE-treated bulk soil (passing a 9.5-mm sieve) was more than double the amount formed in large aggregates (4.76-9.5 mm in diameter). No dinitrogen was detected under the experimental conditions. Results indicate that irrigation with secondary RE stimulates nitrification, which may enhance NO3 leaching losses. This could possibly be a consequence of long-term exposure of the nitrifier population to RE irrigation. Average gross nitrification rate estimates were 11.3 and 15.8 mg N kg(-1) soil d(-1) for FW- and RE-irrigated bulk soils, respectively. Average gross mineralization rate estimates were about 3 mg N kg(-1) soil d(-1) for the two water types.

Risk factors for myocardial infarction case fatality and stroke case fatality in type 2 diabetes: UKPDS 66

OBJECTIVE

Patients with diabetes have a higher case fatality rate in myocardial infarction (MI) or stroke than those without diabetes: that is, MI and stroke are more often fatal if diabetes is present. We investigated whether the risk of MI or stroke being fatal in type 2 diabetes can be estimated using information available around the time diabetes is diagnosed.

RESEARCH DESIGN AND METHODS

Analyses were based on 674 cases of MI (351 fatal) that occurred in 597 of 5,102 U.K. Prospective Diabetes Study (UKPDS) patients for whom covariate data were available during a median follow-up of 7 years. Multivariate logistic regression was used to examine differences in risk factors, measured within 2 years of diagnosis of diabetes, between fatal and nonfatal MI. Similar analyses were performed for 234 strokes (48 fatal) that occurred in 199 patients.

RESULTS

Patients with fatal MI had higher HbA(1c) than those with nonfatal MI (odds ratio 1.17 per 1% HbA(1c), P = 0.014). Patients with fatal stroke had higher HbA(1c) than those with nonfatal stroke (odds ratio 1.37 per 1% HbA(1c), P = 0.007). Other risk factors for MI case fatality included increased age, blood pressure, and urine albumin level.

CONCLUSIONS

The risk of MI or stroke being fatal in type 2 diabetes is associated with risk factors, including HbA(1c), measured many years before onset of MI or stroke. Equations have been added to the UKPDS Risk Engine to estimate likely case fatality rates in MI and stroke.

Gaseous nitrogen emissions and mineral nitrogen transformations as affected by reclaimed effluent application

Irrigation with reclaimed effluent (RE) is essential in arid and semiarid regions. Reclaimed effluent has the potential to stimulate gaseous N losses and affect other soil N processes. No direct measurements of the N2 and N2O emissions from Mediterranean soils have been conducted so far. We used the 15N gas flux method in a field and a laboratory experiment to study the effect of RE irrigation on gaseous N losses and other N transformations in a Grumosol (Chromoxerert) soil. The fluxes of N2, N2O, and NH3 were measured from six Grumosol lysimeters following application of either fresh water or RE. The N fertilizer was applied either as 15NH4 or 15NO3. Only up to 0.3% from the applied N fertilizer was lost as N2O + NH3. Reclaimed effluent enhanced the losses of NH3, but did not affect those of N2O. Nitrification and denitrification were equally important to N2O production. Laboratory incubations were performed to both confirm the influence of the irrigation water type and to test the effect of moisture content. Significant quantities of N2 and N2O (up to 3.1% of the applied fertilizer) were emitted from saturated soils. Reclaimed effluent application did not induce higher N2O emissions, yet significantly more (approximately 33%) N2 was emitted from RE-irrigated soils. Denitrification contributed up to 75% of the N2O amounts emitted from saturated soils. Reclaimed effluent application inhibited nitrification in the Grumosol by 15 to 25% and induced NO2 accumulation in soils incubated at a field-capacity moisture content.

Diffuse endothelial dysfunction is common to ANCA associated systemic vasculitis and polyarteritis nodosa

BACKGROUND

Excess cardiovascular mortality complicates systemic rheumatic disease, suggesting an accelerated atheromatous process, which it has been proposed relates to the vascular inflammation common in such diseases. Impaired endothelium dependent vasodilatation is an early marker of atheromatous disease. It has previously been shown that such endothelial cell dysfunction (ECD) occurring in the brachial artery can complicate primary systemic necrotising vasculitis (SNV).

OBJECTIVE

To determine if ECD occurs in a wider spectrum of primary SNV, if it is restricted to the major arteries, and whether vasculitis subgroup, ANCA status, or renal involvement influenced the endothelial responses.

METHODS

Fifty four patients attending the Birmingham vasculitis clinic, including patients with a range of ANCA and non-ANCA associated primary vasculitides, and a group of age matched controls were recruited. The length of patient follow up and disease activity was variable. Disease activity, damage scores, and cardiovascular risk factors were recorded before assessment of flow mediated brachial artery vasodilatation by high resolution ultrasound. Dermal microvascular responses to acetylcholine were also measured in 32 patients and 21 controls by laser Doppler flowmetry.

RESULTS

ECD was demonstrated in all primary SNV subgroups of patients with ANCA associated vasculitis and in polyarteritis nodosa, compared with controls. Significant impairment occurred in both vascular beds, regardless of vessel size targeted in the inflammatory vasculitis, ANCA association and titre, or renal involvement.

CONCLUSIONS

Diffuse endothelial dysfunction, a predictor of atherosclerotic disease, is found extensively in primary systemic vasculitis. Involvement of different vascular beds is independent of target vessel size or ANCA association, and is unrelated to local disease expression. It is suggested that this results from a systemic response that may be a consequence of primary vasculitis, but is distinct from the local inflammatory vasculitic process.

Development and progression of nephropathy in type 2 diabetes: the United Kingdom Prospective Diabetes Study (UKPDS 64)

BACKGROUND

The progression of nephropathy from diagnosis of type 2 diabetes has not been well described from a single population. This study sought to describe the development and progression through the stages of microalbuminuria, macroalbuminuria, persistently elevated plasma creatinine or renal replacement therapy (RRT), and death.

METHODS

Using observed and modeled data from 5097 subjects in the UK Prospective Diabetes Study, we measured the annual probability of transition from stage to stage (incidence), prevalence, cumulative incidence, ten-year survival, median duration per stage, and risk of death from all-causes or cardiovascular disease.

RESULTS

From diagnosis of diabetes, progression to microalbuminuria occurred at 2.0% per year, from microalbuminuria to macroalbuminuria at 2.8% per year, and from macroalbuminuria to elevated plasma creatinine (>or=175 micromol/L) or renal replacement therapy at 2.3% per year. Ten years following diagnosis of diabetes, the prevalence of microalbuminuria was 24.9%, of macroalbuminuria was 5.3%, and of elevated plasma creatinine or RRT was 0.8%. Patients with elevated plasma creatinine or RRT had an annual death rate of 19.2% (95% confidence interval, CI, 14.0 to 24.4%). There was a trend for increasing risk of cardiovascular death with increasing nephropathy (P < 0.0001), with an annual rate of 0.7% for subjects in the stage of no nephropathy, 2.0% for those with microalbuminuria, 3.5% for those with macroalbuminuria, and 12.1% with elevated plasma creatinine or RRT. Individuals with macroalbuminuria were more likely to die in any year than to develop renal failure.

CONCLUSIONS

The proportion of patients with type 2 diabetes who develop microalbuminuria is substantial with one quarter affected by 10 years from diagnosis. Relatively fewer patients develop macroalbuminuria, but in those who do, the death rate exceeds the rate of progression to worse nephropathy.

Accelerated atherogenesis in autoimmune rheumatic diseases

The observation that systemic inflammatory rheumatic diseases such as rheumatoid arthritis (RA) are associated with a significantly increased rate of cardiovascular disease, which often occurs at a younger age than in the normal population, is particularly important given the increasing interest in the role of inflammation in atherogenesis in the general population. This review examines the accumulating evidence for accelerated atherogenesis of RA and updates the hypothesis that vasculitis plays a major role in this. Endothelial dysfunction (ECD), widely regarded as initial lesion in atherogenesis, has been shown to occur commonly in primary vasculitis. This ECD is a diffuse event, demonstrable in more than one vascular bed. It is not simply due to scarring in the vessel wall, related to the focal inflammation of the underlying vasculitis, since it may be reversed by suppression of the immune inflammation. However, the mechanisms for this ECD differ from that of the primary vasculitis. Preliminary evidence suggests that inflammatory mediators such as CRP, TNF, or sphingolipids may be involved. The diffuse ECD of vasculitis may have important consequences for both the progression of the primary disease and for cardiovascular events. A model for the role of vasculitis-induced ECD in the accelerated atherogenesis of rheumatic diseases is presented. These concepts are discussed together with the messages they suggest for 'idiopathic' atherosclerosis in the general population.

UKPDS58--modeling glucose exposure as a risk factor for photocoagulation in type 2 diabetes

In type 2 diabetes, the risk of retinopathy, and of retinal photocoagulation, rises with time after diagnosis of diabetes. In this paper, mathematical modeling shows that this ageing effect is attributable to the rise in glycemia with time since diagnosis of diabetes. Mathematical models were fitted to data from 3,648 patients from the UK Prospective Diabetes Study (UKPDS). A proportional hazards model, in which time and glycemia measured by HbA(1c) are independent risk factors for photocoagulation, was compared to a model in which time does not contribute except through a measure of cumulative glucose exposure. Since likelihood ratio tests cannot be applied to non-nested models, graphical methods were used to compare the two models. The glucose exposure model was able to fit variation in survival with time at least as well as the proportional hazards model. The proportional hazards model, however, seriously underestimates the differences in two groups of different mean HbA(1c). We conclude that duration of diabetes and HbA(1c) level better predict risk for photocoagulation when treated as two components of cumulative glucose exposure, than when treated as independent risk factors.

UKPDS 60: risk of stroke in type 2 diabetes estimated by the UK Prospective Diabetes Study risk engine

BACKGROUND AND PURPOSE

People with type 2 diabetes are at elevated risk of stroke compared with those without diabetes. Relative risks have been examined in earlier work, but there is no readily available method for predicting the absolute risk of stroke in a diabetic individual. We developed mathematical models to estimate the risk of a first stroke using data from 4549 newly diagnosed type 2 diabetic patients enrolled in the UK Prospective Diabetes Study.

METHODS

During 30 700 person-years of follow-up, 188 first strokes (52 fatal) occurred. Model fitting was carried out by maximum likelihood estimation using the Newton-Raphson method. Diagnostic plots were used to compare survival probabilities calculated by the model with those calculated using nonparametric methods.

RESULTS

Variables included in the final model were duration of diabetes, age, sex, smoking, systolic blood pressure, total cholesterol to high-density lipoprotein cholesterol ratio and presence of atrial fibrillation. Not included in the model were body mass index, hemoglobin A1c, ethnicity, and ex-smoking status. The use of the model is illustrated with a hypothetical study power calculation.

CONCLUSIONS

This model forecasts the absolute risk of a first stroke in people with type 2 diabetes using variables readily available in routine clinical practice.

UKPDS 59: hyperglycemia and other potentially modifiable risk factors for peripheral vascular disease in type 2 diabetes

OBJECTIVE

To determine the role of hyperglycemia in prospective analyses of peripheral vascular disease (PVD) in type 2 diabetes, taking into account other potential risk factors.

RESEARCH DESIGN AND METHODS

Potential risk factors for the development of PVD were examined in 3,834 of 5,102 individuals enrolled in the U.K. Prospective Diabetes Study (UKPDS) without PVD at diagnosis of diabetes, followed for 6 years, and for whom relevant data were available. PVD was defined as two of the following: ankle-arm blood pressure index < 0.8, absence of both dorsalis pedis and posterior tibial pulses to palpation in one or both legs, and intermittent claudication. Logistic regression was used to estimate the association between potential risk factors measured 3-4 months after diagnosis of diabetes and incident PVD. The prevalence of PVD at 3-year intervals to 18 years was determined.

RESULTS

Hyperglycemia, assessed as HbA(1c), was associated with an increased risk for incident PVD, independent of other risk factors including age, increased systolic blood pressure, reduced HDL cholesterol, smoking, prior cardiovascular disease, peripheral sensory neuropathy, and retinopathy. Each 1% increase in HbA(1c) was associated with a 28% increased risk of PVD (95% CI 12-46), and each 10-mmHg increase in systolic blood pressure with a 25% increase in risk (95% CI 10-43).

CONCLUSIONS

Hyperglycemia, as well as smoking, dyslipidemia, and blood pressure are potentially modifiable risk factors for the development of PVD.

The UKPDS risk engine: a model for the risk of coronary heart disease in Type II diabetes (UKPDS 56)

A definitive model for predicting absolute risk of coronary heart disease (CHD) in male and female people with Type II diabetes is not yet available. This paper provides an equation for estimating the risk of new CHD events in people with Type II diabetes, based on data from 4540 U.K. Prospective Diabetes Study male and female patients. Unlike previously published risk equations, the model is diabetes-specific and incorporates glycaemia, systolic blood pressure and lipid levels as risk factors, in addition to age, sex, ethnic group, smoking status and time since diagnosis of diabetes. All variables included in the final model were statistically significant (P<0.001, except smoking for which P=0.0013) in likelihood ratio testing. This model provides the estimates of CHD risk required by current guidelines for the primary prevention of CHD in Type II diabetes.

Effect of liquid manure on the mole fraction of nitrous oxide evolved from soil containing nitrate

The same emission factor is applied to fertiliser N and manure N when calculating national N2O inventories. Manures and fertilisers are often applied together to meet the N needs of the crop, but little is known about potential interactions leading to an increase in denitrification rate or a change in the composition of the end-products of denitrification. We used the 15N gas-flux method in a laboratory experiment to quantify the effect of liquid manure (LM) application on the fluxes of N2 and N2O when the soil contained fertiliser 15NO3-. LM increased the mole fraction of N2O from 0.5 to 0.85 in the first 12 h after application. More than 94% of the N2O was from the reduction of NO3-, probably due to aerobic nitrate respiration as well as respiratory denitrification.

Nitrous oxide and dinitrogen emissions from soil under different water regimes and straw amendment

In a laboratory study, soil amended with and without wheat straw (2.8 g kg(-1) soil) was incubated under 70% water holding capacity (WHC), continuously flooded and flooded/drained cycle conditions at 30 degrees C for 51 days. Dinitrogen and N2O evolution and ammonia volatilisation were measured during the incubation. Extractable NH4+-N and NO3--N were determined at the end of the incubation. Entrapped N2, N2O, and dissolved NH4+-N and NO3--N in drainage water were measured in the flooded/drained cycle treatment when the floodwater was drained. The results indicated that N loss through ammonia volatilisation was undetected in all treatments due to the low soil pH value (pHH2O= 5.87) and no air movement. The recovery of urea-15N as N2 was lowest in the continuously flooded treatments (0.75% and 0.96% with and without straw amendment, respectively), highest in the 70% WHC treatments (5.65% and 4.41%, respectively), and intermediate in the flooded/drained cycle treatments (1.79% and 2.65%, respectively). The recovery of urea-15N as N2O was in the same order as that of N2, negligible in the continuously flooded treatments, 0.01% and 0.07% in the flooded/drained cycle treatments, and 1.29% and 2.23% in the 70% WHC treatments, respectively. Peak N2O evolution rates were observed after the floodwater was drained but no substantial evolution was found after the soil was reflooded following drained periods. However, peak N2 evolution rates were observed after the onset of both drainage and re-flooding. Considerable quantities of N2 but no detectable N2O were entrapped in the flooded soil.

Propagation and neural regulation of calcium waves in longitudinal and circular muscle layers of guinea pig small intestine

BACKGROUND & AIMS

The relative movements of longitudinal muscle (LM) and circular muscle (CM) and the role that nerves play in coordinating their activities has been a subject of controversy. We used fluorescent video imaging techniques to study the origin and propagation of excitability simultaneously in LM and CM of the small intestine.

METHODS

Opened segments of guinea pig ileum were loaded with the Ca(2+) indicator fluo-3. Mucosal reflexes were elicited by lightly depressing the mucosa with a sponge.

RESULTS

Spontaneous Ca(2+) waves occurred frequently in LM (1.2 s(-1)) and less frequently in CM (3.2 min(-1)). They originated from discrete pacing sites and propagated at rates 8-9 times faster parallel (LM, 87 mm/s; CM, 77 mm/s) compared with transverse to the long axis of muscle fibers. The presence of Ca(2+) waves in one muscle layer did not affect the origin, rate of conduction, or range of propagation in the other layer. The extent of propagation was limited by collisions with neighboring waves or recently excited regions. Simultaneous excitation of both muscle layers could be elicited by mucosal stimulation of either ascending or descending reflex pathways. Neural excitation resulted in an increase in the frequency of Ca(2+) waves and induction of new pacing sites without eliciting direct coupling between layers.

CONCLUSIONS

Localized, spontaneous Ca(2+) waves occur independently in both muscle layers, promoting mixing (pendular or segmental) movements, whereas activation of neural reflexes stimulates Ca(2+) waves synchronously in both layers, resulting in strong peristaltic or propulsive movements.

Optimum intermittent pneumatic compression stimulus for lower-limb venous emptying

OBJECTIVE

intermittent pneumatic compression (IPC) of the foot (IPC(foot)), calf (IPC(calf)) or both (IPC(foot+calf)) augments calf inflow, and improves the walking ability and peripheral haemodynamics of claudicants (IPC(foot), IPC(foot+calf)), largely due to venous outflow enhancement. This cohort study, using direct pressure measurements in healthy limbs, determines the optimal combination of frequency (2-4 impulses/minute), applied pressure (60-140 mmHg), mode (IPC(foot)-IPC(calf)-IPC(foot+calf)) and delay time of calf-to-foot impulse (0 s-0.5 s-1 s) that enables IPC to generate an almost complete and sustained decrease in venous pressure.

RESULTS

(a) IPC(foot)at 120 and 80 mmHg generated lower venous pressure than that with 100 and 60 mmHg (p=0.036) respectively, for 2-4 impulses/minute; venous pressure differences between applied pressures of 140 and 120 mmHg or between 80 and 100 mmHg were insignificant. (b) Venous pressure with IPC(calf)at 80 mmHg was lower than that with 60 mmHg (p=0.036) (2-4 cycles/minute); differences in venous pressure between applied pressures of 140 and 100 mmHg or between 120 and 80 mmHg were insignificant. (c) At applied pressures 60-140 mmHg, IPC(foot+calf)with one-second delay generated lower venous pressure than that with half-second delay (p=0.036), the latter being more efficient than zero delay; increasing applied pressures produced lower venous pressure, but differences were small. Venous pressure decreased with increasing IPC frequency (from 2 to 3-4/minute), at applied pressures 60-140 mmHg.

CONCLUSIONS

IPC(foot+calf)at applied 120-140 mmHg, a frequency of 3-4 impulses/minute and one-second delay, provided the optimum intermittent pneumatic stimulus.

Visualization of origins and propagation of excitation in canine gastric smooth muscle

The origin and spread of excitation were visualized with fluo 3 fluorescence in tissues isolated from canine gastric antrum. Sheets of circular muscle (5 x 6 mm) had at least 1 (30%) and up to 3 discrete slow-wave pacing sites located near the longitudinal-circular muscle boundary, whereas similarly sized longitudinal sheets had an average of 5 sites (range 3-12 sites) that initiated Ca2+ waves. Superimposed fluorescent oscillations (circular muscle) and spikes (longitudinal muscle) were seen to initiate and propagate as distinct events, separate from their underlying activities. Average propagation velocities transverse (6-7 mm/s) and parallel (39-45 mm/s) to the long axis of muscle fibers were similar for each type of event in circular and longitudinal tissues; however, distinct regions where velocities of some (but not all) events decreased by up to an order of magnitude were present. The distance propagated by individual events was limited by collisions with concurrent excitable events or recently activated regions. Complex patterns of excitation in gastrointestinal smooth muscle arise as a result of interactions between multiple pacing sites, heterogeneous conduction velocities, and the interplay of adjacent pacemaker domains.

Induction and organization of Ca2+ waves by enteric neural reflexes

The motility of the gastrointestinal tract consists of local, non-propulsive mixing (pendular or segmental) and propulsive (peristaltic) movements. It is generally considered that mixing movements are produced by intrinsic pacemakers which generate rhythmic contractions, and peristalsis by intrinsic excitatory and inhibitory neural reflex pathways, but the relationship between mixing and peristalsis is poorly understood. Peristalsis is compromised in mice lacking interstitial cells of Cajal, suggesting that these pacemaker cells may also be involved in neural reflexes. Here we show that mixing movements within longitudinal muscle result from spontaneously generated waves of elevated internal calcium concentration which originate from discrete locations (pacing sites), spread with anisotropic conduction velocities in al directions, and terminate by colliding with each other or with adjacent neurally suppressed regions. Excitatory neural reflexes control the spread of excitability by inducing new pacing sites and enhancing the overall frequency of pacing, whereas inhibitory reflexes suppress the ability of calcium waves to propagate. We provide evidence that the enteric nervous system organizes mixing movements to generate peristalsis, linking the neural regulation of pacemakers to both types of gut motility.

Thalidomide in the treatment of the cutaneous manifestations of lupus erythematosus: experience in sixteen consecutive patients

We review the efficacy, tolerability and safety of low-dose thalidomide in the treatment of refractory disfiguring rash in 16 patients with cutaneous manifestations of lupus. Rashes, which included discoid lupus erythematosus (DLE), subacute cutaneous lupus (SCLE), photosensitive malar rash and non-specific chronic erythema, were diagnosed on clinical grounds, supported by skin biopsy in 11/16 patients. Using starting doses of 50-100 mg/day, 7/16 (44%) patients gained complete or near-complete remission of skin disease and 6/16 (37%) partial remission. Three out of 16 patients failed to respond. Maximum benefit was achieved within 16 weeks in all patients. Doses of 25-50 mg/day were effective in maintaining response. Rapid relapse occurred in 6/8 (75%) patients following drug withdrawal, but the response to thalidomide in those requiring repeat courses appeared to be maintained. There was no detectable improvement in systemic disease. One patient developed symptoms of mild peripheral neuropathy which resolved on drug withdrawal. Our experience suggests that thalidomide is effective in the treatment of severe skin manifestations of lupus refractory to other treatment and can be used safely in specialist rheumatological practice.

Rapid, Sensitive and Highly Selective (15)N Analysis of (15)N Enriched Nitrite in Water Samples and Soil Extracts by Nitric Oxide Production and CF-QMS Measurement

Abstract Nitrite is a very important intermediate in many microbiological N transformations in soils and water. The stable isotope (15)N is often used to investigate these processes. The determination of (15)N in low concentrations of nitrite in the presence of large concentrations of nitrate is very difficult. Methods used so far for the isotope analysis of nitrite are unsatisfactory, because the nitrite must be calculated as the difference between nitrate plus nitrite and nitrate alone. More useful are mehods by which the nitrite is selectively converted into a chemical form that is suitable for (15)N analysis and that is free from interference from other N species, particularly nitrate. Using this principle in the present study we developed a method where the nitrite is reduced to nitric oxide by iodide in acid medium. This reaction is fast and quantitative, and the (15)N abundance of NO can be precisely measured by continuous flow mass spectrometry. This method is used for samples from tracer experiments with artificially enriched nitrogen 15. Therefore, the use of simple quadrupole mass spectrometers directly linked to the reaction unit is possible with sufficient precision (Reaction-Continuous Flow Quadrupole Mass Spektrometry-RCFQMS). Using the technique developed sample volumes up to 10ml containing at least 1.0 μg nitrite-N (0, 1 μg/ml) with a (15)N abundance of ⩾ 0.42 at.% gave a precision of RSD ⩽ ± 3%.

Accuracy and precision for measurements of the mass ratio 30/28 in dinitrogen from air samples and its application to the investigation of N losses from soil by denitrification

Abstract In the 1950s Hauck introduced a special version of the (15)N dilution technique ((15)N flux method) for the determination of N losses from the soil by denitrification. Although this method is very useful and reliable its application has been rather infrequent up to now. This is mainly due to the need to measure the m/z 30 in addition to the usually measured m/z 28 and 29 for dinitrogen, because the (15)N in the enriched air sample taken from an enclosure (cover box) at the soil surface is nonrandom. The signal from the m/z 30 is very low and difficult to measure with sufficient precision because other species (e.g. NO) also having the m/z 30 often interfere with its measurement. In this study the accuracy and precision of an easy to use CF-IRMS with sample batch operation to measure the ratio 30/28 was investigated. The relative standard deviation (RSD = precision) from natural abundance up to 2 at.% was always <1%. After correction of the mass ratio 30/28 (R30), by means of a formula obtained by linear regression of theoretical R30 against measured R30, the accuracy of the abundance calculated from this corrected R30 was very high. From the achieved precision and assuming a cover box height of 10 cm (headspace volume of 7 1), and a collection time of 2 h, a limit of detection for N(2) losses by denitrification equivalent to 16 g N/ha*d or 6 kg N/ha*a can be estimated. The performance of the (15)N dilution method using the equipment and procedure described is demonstrated by means of results from an incubation experiment with [(15)N]nitrate-amended soils.

The aetiopathogenesis of giant cell arteritis

In this review, current understanding of the aetiopathogenesis of giant cell arteritis is examined. Possible explanations for the late age of onset and striking responsiveness to steroid therapy.

Gastroschisis: a birth defect seen in increasing numbers in Oklahoma?

OBJECTIVE

To identify if an actual increase in children born with gastroschisis is occurring in Oklahoma. To compare findings with historical and current literature concerning the incidence of this congenital malformation of the abdominal wall.

DATA

Derived from Children's Hospital of Oklahoma (CHO) medical records, inventory sheets completed by nurses and resident physicians on admission of gastroschisis infants at CHO, hospital records of Tulsa pediatric surgeons (Subramania Jegathesan, MD, and Richard Ranne, MD), and the state health departments of Oklahoma and Iowa.

FINDINGS

1. Increase in number of gastroschisis children born in Oklahoma. 2. Comparable findings in the state of Iowa. 3. No specific maternal or environmental factor to account for increase.

CONCLUSIONS

Children born with gastroschisis in Oklahoma and other areas of the country, as well as internationally, have shown an increase in number over the past two decades. This increase cannot be attributed to any one identifiable factor.

Effect of hypothyroidism on the expression of cytochrome c and cytochrome c oxidase in heart and muscle during development

The effect of thyroid hormone on the expression of mitochondrial proteins was evaluated during development by measuring cytochrome c oxidase (CYTOX) activity and cytochrome c protein and mRNA levels in heart and skeletal muscle of control and hypothyroid rats. Animals were killed at the late fetal, early, and late postnatal stages up to 56 days of age. In heart, CYTOX activity increased 2.3-fold above the fetal level throughout development, most of which occurred prior to 2 days of age. No increase was observed in muscle. CYTOX activity was reduced in hypothyroid animals throughout development in heart compared to controls (by 50% at 56 days), but in muscle no effect of hypothyroidism was observed. In muscle and heart 4- and 1.5-fold increases in cytochrome c above the fetal level were evident by 1 day of age, with further increases to 8.5- and 2.7-fold by 56 days, respectively. The increase in cytochrome c differed from the increase in CYTOX, indicating changes in mitochondrial composition. Hypothyroidism reduced cytochrome c in muscle by 30-35% at 56 days, but had no effect in heart, indicating a muscle type-specific effect of thyroid hormone on cytochrome c protein expression. Cytochrome c mRNA increased rapidly to 4-5 fold above the fetal level in both heart and muscle by 6 h post-partum. Between 7 and 56 days of age, further increases to 6- and 25-fold were observed in muscle and heart, respectively. In muscle, the 6-fold developmental increase in mRNA paralleled that of the protein, suggesting transcriptional regulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Dog bites in children

Dog bites, a common cause of traumatic injury, tend to be a greater source of morbidity and mortality in children than in adults. We evaluated 13 children, who, during a 10-year period, required surgical intervention for dog bites. The greatest cause of morbidity in these children was the penetrating component of the dog bite. Most initial evaluations focused on the crushing component of the bite, but in children with serious dog bites, wounds must be evaluated with respect to both the crushing and penetrating injury components.

Properties of skeletal muscle mitochondria isolated from subsarcolemmal and intermyofibrillar regions

Two mitochondrial fractions, termed intermyofibrillar (IMF) and subsarcolemmal (SS), were isolated from skeletal muscle, and their biochemical properties were related to differences in respiration and mitochondrial protein synthesis. State III respiration was 2.3- to 2.8-fold greater in IMF than in SS mitochondria. Site 1 inhibition of respiration with rotenone reduced this difference to 1.4-fold. When sites 1 and 2 were inhibited with antimycin, the 1.4-fold differences remained. The activities of cytochrome-c oxidase (CYTOX) and succinate dehydrogenase (SDH) could account for some of these differences, since CYTOX was 20% greater (P < 0.05) in IMF mitochondria, and SDH was 40% greater (P < 0.05) in SS mitochondria. Cytochromes a, b, c, and c1 contents were similar in the two fractions. Cardiolipin (CL) content was higher (P < 0.05) in SS mitochondria, indicating a less dense mitochondrial fraction with respect to CL. In vitro [3H]leucine incorporation was 1.8-fold higher (P < 0.05) in IMF than in SS mitochondria. Thus compositional differences between IMF and SS fractions exist, perhaps representing mitochondria at different stages of biogenesis. The biochemical and functional differences could not solely be due to differences in mitochondrial protein synthesis but could also be due to nuclear-directed protein synthesis specific to each mitochondrial fraction.

Electrical and mechanical effects of acetylcholine and substance P in subregions of canine colon

Effects of acetylcholine (ACh) and substance P on the electrical and mechanical activities of the circular muscle layer of the canine proximal colon were studied. Because this muscle layer is bordered by two different pacemaker regions, responses from segments containing either a single pacemaker region or no pacemaker region were compared with responses of the complete muscle layer. Concentration-response relationships for ACh and substance P were similar between the various segments, suggesting that receptors for these agonists are expressed throughout the layer. The dominant contractile pattern induced by ACh and substance P in each segment was a 1- to 3-cycle/min rhythm. In a like manner, these agonists also elicited an electrical pattern in which a long-duration slow wave occurred one to three times per minute between short-duration slow waves. Low concentrations of nifedipine (0.01 microM) selectively antagonized the 1- to 3-cycle/min rhythm. In circular muscles with no pacemaker region, ACh (1 microM) caused depolarization, induced oscillations in membrane potential averaging 24 +/- 5 mV in amplitude and 2.9 +/- 0.9 cycles/min in frequency, and generated rhythmic contractions at the same frequency. This "interior" circular muscle was functionally innervated by cholinergic excitatory nerves. Exposure to ACh (1 microM) did not alter the conduction of slow waves through the thickness of the circular layer. In summary, the excitatory neurotransmitters, ACh and substance P, induce a dominant electrical and contractile rhythm throughout the circular muscle layer that is different from the spontaneous rhythms produced at either the myenteric or submucosal border.

Simultaneous measurement of membrane potential, cytosolic Ca2+, and tension in intact smooth muscles

Microelectrode techniques and the fluorescent Ca2+ indicator indo-1 were used to measure membrane potential, cytosolic Ca2+ ([Ca2+]cyt), and muscle tension simultaneously in canine antral smooth muscles. Responses of muscles from the myenteric and submucosal regions were compared, since electrical activity and excitation-contraction coupling in these regions differ. The upstroke phase of electrical slow waves in both regions induced an increase in [Ca2+]cyt. In myenteric muscles the plateau phase of slow waves often caused either a further rise in [Ca2+]cyt or maintenance of the level reached during the upstroke event. In submucosal muscles, the plateau phase was significantly smaller and did not induce a second phase in the Ca2+ transient. Contractions were related to the amplitudes of Ca2+ transients. Acetylcholine (ACh; 3 x 10(-8)-10(-6) M) increased the amplitude and duration of the plateau phase of slow waves in a concentration-dependent manner. ACh also increased the second phase of Ca2+ transients and contractile responses associated with the plateau potential. In submucosal muscles ACh induced a significant increase in the plateau phase of the slow wave and increased the corresponding phase of Ca2+ transient. Nicardipine (10(-6) M) inhibited plateau phase of slow waves and the associated increases in [Ca2+]cyt and muscle tension. BAY K 8644 (10(-7) M) augmented the plateau potential and increased [Ca2+]cyt and muscle tension. These results suggest that dihydropyridine-sensitive Ca2+ currents participate in the plateau potential. Cholinergic stimulation modulates [Ca2+]cyt and therefore force by regulating the amount of Ca2+ entering cells through these channels.

Effect of cromakalim and lemakalim on slow waves and membrane currents in colonic smooth muscle

The effects of cromakalim (BRL 34915) and its optical isomer lemakalim (BRL 38227) were investigated in intact tissue and freshly dispersed circular muscle cells from canine proximal colon. Cromakalim and lemakalim hyperpolarized resting membrane potential, shortened the duration of slow waves by abolishing the plateau phase, and decreased the frequency of slow waves. Glyburide, a K channel blocker, prevented the effect of cromakalim on slow-wave activity. The mechanisms of these alterations in slow-wave activity were studied in isolated myocytes under voltage-clamp conditions. Cromakalim and lemakalim increased the magnitude of a time-independent outward K current, but cromakalim also reduced the peak outward K current. Glyburide inhibited lemakalim stimulation of the time-independent background current. Nisoldipine also reduced the peak outward current, and in the presence of nisoldipine, cromakalim did not affect the peak outward component of current. This suggested that cromakalim may block a Ca-dependent component of the outward current. Lemakalim did not affect the peak outward current. We tested whether the effects of cromakalim on outward current might be indirect due to an effect on inward Ca current. Cromakalim, but not lemakalim, was found to inhibit L-type Ca channels; however, glyburide did not alter cromakalim inhibition of inward Ca current. We conclude that the effects of cromakalim and lemakalim on membrane potential and slow waves in colonic smooth muscle appear to result primarily from stimulation of a time-independent background K conductance. The effects of these compounds on channel activity may explain the inhibitory effect of these compounds on contractile activity.

Analysis of emergency physician data can pay off

A hospital's emergency physician billing procedures and fee schedules may not have kept pace with changes in the make-up of emergency room personnel. Revisions require thorough analysis of coding procedures, payer and patient data, Medicare rates, and breakdowns of collections. A successful analysis may yield improved collections, increased physician compensation, and separate billing by emergency physicians.

Mathematical model for interpretation of Doppler velocity waveform indices

Various empirical indices such as the pulsatility index (PI) are widely used for quantitative analysis of Doppler ultrasound velocity waveforms. The physical interpretation of these indices was studied using a mathematical model. Although the method has more general applicability, this particular study was concerned with the umbilical-placental circulation. A lumped element electrical circuit equivalent was used, with each arterial branch represented by a resistor and a capacitor. The placental villous bed was modelled by a two-step parallel branching structure. Placental vascular disease was modelled either as obliteration of a fraction of the terminal branches, or as a fractional decrease in the radius of the vessels. The main features of both normal and abnormal umbilical artery waveforms can be reproduced by this simple model. Theoretical relationships between the velocity waveform indices and the lumped resistances and capacitance of the system were obtained for different input pressure functions. Over a wide range of physically reasonable conditions, the umbilical artery PI is approximately proportional to the ratio of the placental resistance to the umbilical artery resistance. The PI also depends on the pulsatility of the input pressure waveform. The Fourier pulsatility index was evaluated for an arbitrary pressure function, and shown to behave like (PI)2 for the umbilical artery waveform.

Effects of methylene blue on rhythmic activity and membrane potential in the canine proximal colon

The hypothesis that methylene blue has a direct effect on colonic muscle cells was tested. Intracellular recordings were made from cross-sectional preparations of canine proximal colon. Cells through the circular layer were impaled and membrane potentials ranging from -81 mV at the submucosal surface to -46 mV at the myenteric border were recorded. Methylene blue (10(-5) M) depolarized cells near the submucosal border by an average of 43 mV and slow-wave activity ceased. The loss of slow-wave activity could be explained by the depolarizing effects of methylene blue rather than a specific effect of methylene blue on the pacemaker mechanism. Other experiments suggested that the depolarizing effects of methylene blue were not confined to muscle cells within the submucosal pacemaker region. Depolarization of cells was noted throughout the circular layer, but the magnitude of the depolarization decreased with distance from the submucosal border. After methylene blue, the gradient in resting potential across the circular layer was greatly reduced or abolished. The data suggest that methylene blue is not necessarily a specific probe for interstitial cells and has direct effects on smooth muscle cells in the canine proximal colon. This effect is similar to treatments that are known to block the electrogenic sodium pump.

Human cytomegalovirus infections in vitro after treatment with arildone

Arildone (WIN 38020), a broad spectrum antiviral, aryl-beta-diketone (4-[6-(2-chloro-4-methoxy)phenoxyl]hexyl-3,5-heptanedione), blocks the replication of human cytomegalovirus at a stage prior to the synthesis of virus-specific DNA. Inhibitory action was demonstrated against a number of virus isolates from neonates and immune-compromised patients. Intranuclear sites of virus replication, highlighted by DNA-staining methods or immunofluorescence, were absent after Arildone treatment and corresponded with the lack of ultrastructural changes associated with productive infection. The abundance of early antigens in cells treated with Arildone was evidence for expression of the viral genome and this was confirmed by detection of immediate-early viral proteins in the presence of the drug. The results suggest that Arildone prevents the replication of human cytomegalovirus at a stage after virion uncoating but prior to viral DNA synthesis.