Long-term outcome of persons with diabetic and non-diabetic neuro-osteoarthropathy after foot correction using external fixation

AIM

Diabetic neuro-osteoarthropathy (Charcot foot) is a serious form of diabetic foot syndrome, often leading to severe deformity of the foot and subsequently to ulcers and osteomyelitis. The aim of this retrospective study was to determine the success rate and long-term outcomes for a Charcot foot operation using external fixation in 115 individuals who underwent surgery between July 2008 and December 2012.

METHODS

Some 115 consecutive persons, 78 (68%) men and 37 (32%) women, were enrolled in this study. The eligibility criterion for this retrospective study was reconstructive foot surgery using a Hoffmann II external fixator in diabetic and non-diabetic neuro-osteoarthropathy. The main examination parameters in the follow-up were walking ability, amputation and mortality. Average follow-up was 5.7 (± 3.2) years.

RESULTS

Ninety-seven per cent of people were able to walk after the operation with bespoke shoes or an orthosis. At follow-up, 77% were able to walk and 51% were fully mobile even outside the home. Subsequent amputations were performed in 29 individuals (26%), with 17 (15%) minor and 12 (11%) major amputations. Forty-seven individuals died before follow-up, the majority (53%) from cardiovascular events. Average survival time post surgery was 4.5 (± 2.9) years.

CONCLUSION

Reconstruction surgery using external fixation is a very useful method for maintaining walking ability in the case of conservatively non-treatable diabetic and non-diabetic neuro-osteoarthropathy. Individuals with severe Charcot foot disease had a low rate of major amputations. Osteomyelitis was the main reason for major amputations.

Minor amputation does not negatively affect health-related quality of life as compared with conservative treatment in patients with a diabetic foot ulcer: An observational study

BACKGROUND

Health-related quality of life (HRQoL) is poor in patients with persistent diabetic foot ulcers and poor HRQoL predicts worse outcomes in these patients. Amputation is often considered a treatment failure, which is why conservative treatment is generally preferred over amputation. However, it is unclear whether minor amputation negatively affects HRQoL compared with conservative treatment in patients with diabetic foot ulcers.

METHODS

In the cohort of the multicenter, prospective, observational Eurodiale study, we determined difference in change of HRQoL measured by EQ-5D between patients with a diabetic foot ulcers that healed after conservative treatment (n = 676) and after minor amputation (n = 145). Propensity score was used to adjust for known confounders, attempting to overcome lack of randomization.

RESULTS

Baseline HRQoL was not significantly different between patients treated conservatively and undergoing minor amputation. In addition, there was no difference in the change of HRQoL between these groups. In patients who healed 6 to 12 months after the first visit, HRQoL on the anxiety/depression subscale even appeared to improve more in those who underwent minor amputation.

CONCLUSIONS

Minor amputation was not associated with a negative impact on HRQoL in patients with a diabetic foot ulcers. It may therefore not be considered treatment failure in terms of HRQoL but rather a viable treatment option. A randomized controlled trial is warranted to further examine the influence of minor amputations on health-related quality of life.

NMR metabolomics profiling of blood plasma mimics shows that medium- and long-chain fatty acids differently release metabolites from human serum albumin

Metabolite profiling by NMR of body fluids is increasingly used to successfully differentiate patients from healthy individuals. Metabolites and their concentrations are direct reporters of body biochemistry. However, in blood plasma the NMR-detected free-metabolite concentrations are also strongly affected by interactions with the abundant plasma proteins, which have as of yet not been considered much in metabolic profiling. We previously reported that many of the common NMR-detected metabolites in blood plasma bind to human serum albumin (HSA) and many are released by fatty acids present in fatted HSA. HSA is the most abundant plasma protein and main transporter of endogenous and exogenous metabolites. Here, we show by NMR how the two most common fatty acids (FAs) in blood plasma - the long-chain FA, stearate (C18:0) and medium-chain FA, myristate (C14:0) - affect metabolite-HSA interaction. Of the set of 18 common NMR-detected metabolites, many are released by stearate and/or myristate, lactate appearing the most strongly affected. Myristate, but not stearate, reduces HSA-binding of phenylalanine and pyruvate. Citrate signals were NMR invisible in the presence of HSA. Only at high myristate-HSA mole ratios 11:1, is citrate sufficiently released to be detected. Finally, we find that limited dilution of blood-plasma mimics releases HSA-bound metabolites, a finding confirmed in real blood plasma samples. Based on these findings, we provide recommendations for NMR experiments for quantitative metabolite profiling.

Importance of factors determining the low health-related quality of life in people presenting with a diabetic foot ulcer: the Eurodiale study

AIM

To identify the factors responsible for the low health-related quality of life associated with foot ulcers and the relative importance of these factors.

METHODS

A total of 1232 patients with a new foot ulcer, who presented at one of the 14 centres in 10 European countries participating in the Eurodiale study, were included in this cross-sectional study. Patient and ulcer characteristics were obtained as well as results from the Euro-Qol-5D questionnaire, a health-related quality of life instrument with five domains (mobility, self-care, usual activities, pain/discomfort and anxiety/depression). To analyse the relative importance of comorbidities and ulcer- and patient-related factors for health-related quality of life, linear regression models were used to calculate the relative contributions of each factor to the fit (R(2) ) of the model.

RESULTS

Patients reported poor overall health-related quality of life, with problems primarily in the mobility and pain/discomfort domains. Among the comorbidities, the inability to stand or walk without help was the most important determinant of decreased health-related quality of life in all five domains. Among ulcer-related factors, ulcer size, limb-threatening ischaemia and elevated C-reactive protein concentration also had high importance in all domains. The clinical diagnosis of infection, peripheral arterial disease and polyneuropathy were only important in the pain/discomfort domain.

CONCLUSIONS

The factors that determine health-related quality of life are diverse and to an extent not disease-specific. To improve health-related quality of life, treatment should not only be focused on ulcer healing but a multifactorial approach by a specialized multidisciplinary team is also important.

Differences in minor amputation rate in diabetic foot disease throughout Europe are in part explained by differences in disease severity at presentation

OBJECTIVES

The incidence of minor amputation may vary significantly, and determinants of minor amputation have not been studied systematically. We evaluated minor amputation rate, the determinants of minor amputation and differences in amputation rate between European centres.

METHODS

In the Eurodiale study, a prospective cohort study of 1232 patients (1088 followed until end-point) with a new diabetic foot ulcer were followed on a monthly basis until healing, death, major amputation or up to a maximum of 1 year. Ulcers were treated according to international guidelines. Baseline characteristics independently associated with minor amputation were examined using multiple logistic regression modelling. Based on the results of the multivariable analysis, a disease severity score was calculated for each patient.

RESULTS

One hundred and ninety-four (18%) patients underwent a minor amputation. Predictors of minor amputation were depth of the ulcer (odds ratio 6.08, confidence interval 4.10-9.03), peripheral arterial disease (odds ratio 1.84, confidence interval 1.30-2.60), infection (odds ratio 1.56, confidence interval 1.05-2.30) and male sex (odds ratio 1.42, confidence interval 0.99-2.04). Minor amputation rate varied between 2.4 and 34% in the centres. Minor amputation rate in centres correlated strongly with disease severity score at the moment of presentation to the foot clinic (r=0.75).

CONCLUSIONS

Minor amputation is performed frequently in diabetic foot centres throughout Europe and is determined by depth of the ulcer, peripheral arterial disease, infection and male sex. There are important differences in amputation rate between the European centres, which can be explained in part by severity of disease at presentation. This may suggest that early referral to foot clinics can prevent minor amputations.

Serum metabolome analysis by 1H-NMR reveals differences between chronic lymphocytic leukaemia molecular subgroups

Chronic lymphocytic leukaemia (CLL) is a heterogeneous disease exhibiting variable clinical course and survival rates. Mutational status of the immunoglobulin heavy chain variable regions (IGHVs) of CLL cells offers useful prognostic information for high-risk patients, but time and economical costs originally prevented it from being routinely used in a clinical setting. Instead, alternative markers of IGHV status, such as zeta-associated protein (ZAP70) or messenger RNA levels are often used. We report a (1)H-NMR-based metabolomics approach to examine serum metabolic profiles of early stage, untreated CLL patients (Binet stage A) classified on the basis of IGHV mutational status or ZAP70. Metabolic profiles of CLL patients (n=29) exhibited higher concentrations of pyruvate and glutamate and decreased concentrations of isoleucine compared with controls (n=9). Differences in metabolic profiles between unmutated (UM-IGHV; n=10) and mutated IGHV (M-IGHV; n=19) patients were determined using partial least square discriminatory analysis (PLS-DA; R(2)=0.74, Q(2)=0.36). The UM-IGHV patients had elevated levels of cholesterol, lactate, uridine and fumarate, and decreased levels of pyridoxine, glycerol, 3-hydroxybutyrate and methionine concentrations. The PLS-DA models derived from ZAP70 classifications showed comparatively poor goodness-of-fit values, suggesting that IGHV mutational status correlates better with disease-related metabolic profiles. Our results highlight the usefulness of (1)H-NMR-based metabolomics as a potential non-invasive prognostic tool for identifying CLL disease-state biomarkers.

Clinical outcome of using insulin at 40 IU/ml and 100 IU/ml in pump treatment. Results of a controlled multi-center trial

In three different diabetes centers the use of insulin at a strength of 40 IU/ml (U40) and 100 IU/ml (U100) in continuous subcutaneous insulin infusion (CSII) treatment of insulin dependent (Type I) diabetic patients was compared in a randomized cross-over design. Forty-six Type I diabetic patients, all previously treated with CSII for at least one year, completed consecutively two 13-week periods of treatment with U40 and U100. Body weight and insulin requirements were identical at the end of the two periods. Slightly higher levels of glycemia were recorded during U40 when compared to U100 treatment: mean blood glucose was 142 +/- 34 (SD) vs. 133 +/- 34 mg/dl (2 p less than 0.01). The same tendency was observed in the mean glycosylated hemoglobin value (6.84 +/- 1.35 vs. 6.65 +/- 1.13%, 2 p greater than 0.1). There were no significant differences between U40 and U100 in the number of catheters used and the number of catheter blockages reported, while the development of subcutaneous nodules at the insertion sites was significantly more frequent during U40 treatment. It is concluded that the implementation of insulin in the strength of 100 IU/ml is as effective as the use of insulin in the strength of 40 IU/ml for CSII therapy, and might even be associated with slightly improved glycemic control and less subcutaneous side-effects.

Impact of gene-gender effects of adrenergic polymorphisms on hypothalamic-pituitary-adrenal axis activity in depressed patients

OBJECTIVE

There is overwhelming evidence that activation of the hypothalamic-pituitary-adrenal (HPA) system plays a major role in depression and cardiovascular disease in genetically susceptible individuals. We hypothesized that due to the multiple interactions between the sympathetic and the HPA systems via adrenoceptors, polymorphisms in these genes could have an impact on HPA axis activity in major depression.

METHODS

Using the dexamethasone/corticotrophin-releasing hormone (DEX/CRH) test, we investigated the association of alpha(2)-adrenoceptor (ADRA2A -1291C-->G) and the beta(2)-adrenoceptor gene (ADRB2 Arg16Gly) in 189 patients with major depression during the acute state of the disease and after remission.

RESULTS

Male ADRA2A -1291G allele homozygotes showed significant pretreatment HPA axis hyperactivity, with increased adrenocorticotropin (ACTH; F = 4.9, d.f. = 2, p = 0.009) and cortisol responses (F = 6.4, d.f. = 2, p = 0.003). In contrast, female ADRB2 Arg/Arg homozygotes had increased pretreatment ACTH (F = 7.17, d.f. = 2, p = 0.001) and cortisol (F = 8.95, d.f. = 2, p = 0.000) levels. Interestingly, in the respective genotypes, the stress hormones remained elevated in the second DEX/CRH test, despite a reduction in depressive symptoms.

CONCLUSIONS

This study provides evidence that, depending on gender and polymorphisms, there is continuous HPA axis overdrive in a proportion of patients irrespective of the status of depression. Considering the importance of stress hormones for cardiovascular disorders, our data might suggest that these patients are at high risk of comorbidity between depression and cardiovascular disorders.

Resource utilisation and costs associated with the treatment of diabetic foot ulcers. Prospective data from the Eurodiale Study

AIMS/HYPOTHESIS

The aim of the present study was to investigate resource utilisation and associated costs in patients with diabetic foot ulcers and to analyse differences in resource utilisation between individuals with or without peripheral arterial disease (PAD) and/or infection.

METHODS

Data on resource utilisation were collected prospectively in a European multicentre study. Data on 1,088 patients were available for the analysis of resource use, and data on 821 patients were included in the costing analysis. Costs were calculated for each patient by multiplying the country-specific direct and indirect unit costs by the number of resources used from inclusion into the study up to a defined endpoint. Country-specific costs were converted into purchasing power standards.

RESULTS

Resource use and costs varied between outcome groups and between disease severity groups. The highest costs per patient were for hospitalisation, antibiotics, amputations and other surgery. All types of resource utilisation and costs increased with the severity of disease. The total cost per patient was more than four times higher for patients with infection and PAD at inclusion than for patients in the least severe group, who had neither.

CONCLUSIONS/INTERPRETATION

Important differences in resource use and costs were found between different patient groups. The costs are highest for individuals with both peripheral arterial disease and infection, and these are mainly related to substantial costs for hospitalisation. In view of the magnitude of the costs associated with in-hospital stay, reducing the number and duration of hospital admissions seems an attractive option to decrease costs in diabetic foot disease.

Delivery of care to diabetic patients with foot ulcers in daily practice: results of the Eurodiale Study, a prospective cohort study

AIMS

To determine current management and to identify patient-related factors and barriers that influence management strategies in diabetic foot disease.

METHODS

The Eurodiale Study is a prospective cohort study of 1232 consecutive individuals presenting with a new diabetic foot ulcer in 14 centres across Europe. We determined the use of management strategies: referral, use of offloading, vascular imaging and revascularization.

RESULTS

Twenty-seven percent of the patients had been treated for > 3 months before referral to a foot clinic. This varied considerably between countries (6-55%). At study entry, 77% of the patients had no or inadequate offloading. During follow-up, casting was used in 35% (0-68%) of the plantar fore- or midfoot ulcers. Predictors of use of casting were male gender, large ulcer size and being employed. Vascular imaging was performed in 56% (14-86%) of patients with severe limb ischaemia; revascularization was performed in 43%. Predictors of use of vascular imaging were the presence of infection and ischaemic rest pain.

CONCLUSION

Treatment of many patients is not in line with current guidelines and there are large differences between countries and centres. Our data suggest that current guidelines are too general and that healthcare organizational barriers and personal beliefs result in underuse of recommended therapies. Action should be undertaken to overcome these barriers and to guarantee the delivery of optimal care for the many individuals with diabetic foot disease.

Prediction of outcome in individuals with diabetic foot ulcers: focus on the differences between individuals with and without peripheral arterial disease. The EURODIALE Study

AIMS/HYPOTHESIS

Outcome data on individuals with diabetic foot ulcers are scarce, especially in those with peripheral arterial disease (PAD). We therefore examined the clinical characteristics that best predict poor outcome in a large population of diabetic foot ulcer patients and examined whether such predictors differ between patients with and without PAD.

METHODS

Analyses were conducted within the EURODIALE Study, a prospective cohort study of 1,088 diabetic foot ulcer patients across 14 centres in Europe. Multiple logistic regression modelling was used to identify independent predictors of outcome (i.e. non-healing of the foot ulcer).

RESULTS

After 1 year of follow-up, 23% of the patients had not healed. Independent baseline predictors of non-healing in the whole study population were older age, male sex, heart failure, the inability to stand or walk without help, end-stage renal disease, larger ulcer size, peripheral neuropathy and PAD. When analyses were performed according to PAD status, infection emerged as a specific predictor of non-healing in PAD patients only.

CONCLUSIONS/INTERPRETATION

Predictors of healing differ between patients with and without PAD, suggesting that diabetic foot ulcers with or without concomitant PAD should be defined as two separate disease states. The observed negative impact of infection on healing that was confined to patients with PAD needs further investigation.

Prospective randomized controlled study of Hydrofiber dressing containing ionic silver or calcium alginate dressings in non-ischaemic diabetic foot ulcers

AIMS

Diabetic foot ulcers (DFUs) are at risk of infection and impaired healing, placing patients at risk of lower extremity amputation. DFU care requires debridement and dressings. A prospective, multicentre study compared clinical efficacy and safety of AQUACEL Hydrofiber dressings containing ionic silver (AQAg) with those of Algosteril calcium alginate (CA) dressings in managing out-patients with Type 1 or 2 diabetes mellitus and non-ischaemic Wagner Grade 1 or 2 DFUs.

METHODS

Patients stratified by antibiotic use on enrolment were randomly assigned to similar protocols including off-loading, AQAg (n = 67) or CA (n = 67) primary dressings and secondary foam dressings for 8 weeks or until healing. Clinical efficacy measures were healing outcomes and primarily healing speed. Adverse events were recorded.

RESULTS

AQAg and CA groups were comparable at baseline. All ulcer healing outcomes improved in both groups. The mean time to healing was 53 days for AQAg ulcers and 58 days for CA ulcers (P = 0.34). AQAg-treated ulcers reduced in depth nearly twice as much as CA-treated ulcers (0.25 cm vs. 0.13 cm; P = 0.04). There was more overall ulcer improvement and less deterioration in AQAg subjects (P = 0.058), particularly in the subset initially using antibiotics (P = 0.02). Safety profiles of both groups were similar.

CONCLUSION

When added to standard care with appropriate off-loading, AQAg silver dressings were associated with favourable clinical outcomes compared with CA dressings, specifically in ulcer depth reduction and in infected ulcers requiring antibiotic treatment. This study reports the first significant clinical effects of a primary wound dressing containing silver on DFU healing.

High prevalence of ischaemia, infection and serious comorbidity in patients with diabetic foot disease in Europe. Baseline results from the Eurodiale study

AIMS/HYPOTHESIS

Large clinical studies describing the typical clinical presentation of diabetic foot ulcers are limited and most studies were performed in single centres with the possibility of selection of specific subgroups. The aim of this study was to investigate the characteristics of diabetic patients with a foot ulcer in 14 European hospitals in ten countries.

METHODS

The study population included 1,229 consecutive patients presenting with a new foot ulcer between 1 September 2003 and 1 October 2004. Standardised data on patient characteristics, as well as foot and ulcer characteristics, were obtained. Foot disease was categorised into four stages according to the presence or absence of peripheral arterial disease (PAD) and infection: A: PAD -, infection -; B: PAD -, infection +; C: PAD +, infection -; D: PAD +, infection +.

RESULTS

PAD was diagnosed in 49% of the subjects, infection in 58%. The majority of ulcers (52%) were located on the non-plantar surface of the foot. With regard to severity, 24% had stage A, 27% had stage B, 18% had stage C and 31% had stage D foot disease. Patients in the latter group had a distinct profile: they were older, had more non-plantar ulcers, greater tissue loss and more serious comorbidity.

CONCLUSIONS/INTERPRETATION

According to our results in this European cohort, the severity of diabetic foot ulcers at presentation is greater than previously reported, as one-third had both PAD and infection. Non-plantar foot ulcers were more common than plantar ulcers, especially in patients with severe disease, and serious comorbidity increased significantly with increasing severity of foot disease. Further research is needed to obtain insight into the clinical outcome of these patients.

Advancing NMR sensitivity for LC-NMR-MS using a cryoflow probe: application to the analysis of acetaminophen metabolites in urine

Cryogenic cooling of the NMR radio frequency coils and electronics to give greatly enhanced sensitivity is arguably the most significant recent advance in NMR spectroscopy. Here we report the first cryogenic probe built in flow configuration and demonstrate the application to LC-NMR-MS studies. This probe provides superior sensitivity over conventional noncryogenic flow NMR probes, allowing the use of 100 microL of untreated urine (40% less material than previous studies that required preconcentration) and yet revealing drug metabolites hitherto undetected by LC-NMR-MS at 500 MHz. Besides the known sulfate and glucuronide metabolites, previously undetected metabolites of acetaminophen were directly observable in a 15-min on-flow experiment. Simultaneous MS data also provided knowledge on the NMR-silent functional moieties. Further, stop-flow LC-NMR-MS experiments were conducted for greater signal-to-noise ratios on minor metabolites. The cryoflow probe enables the NMR analysis of lower concentrations of metabolites than was previously possible for untreated biofluids. This strategy is generally applicable for samples containing mass-limited analytes, such as those from drug metabolism studies, biomarker and toxicity profiling, impurity analysis, and natural product analysis.

The metabolism of 2-trifluormethylaniline and its acetanilide in the rat by 19F NMR monitored enzyme hydrolysis and 1H/19F HPLC-NMR spectroscopy

The urinary excretion profile and identity of the metabolites of 2-trifluoromethyl aniline (2-TFMA) and 2-trifluoromethyl acetanilide (2-TFMAc), following i.p. administration to the rat at 50 mg kg(-1), were determined using a combination of 19F NMR monitored enzyme hydrolysis, SPEC-MS and 19F/1H HPLC-NMR. A total recovery of approximately 96.4% of the dose was excreted into the urine as seven metabolites. The major routes of metabolism were N-conjugation (glucuronidation), and ring-hydroxylation followed by sulphation (and to a lesser extent glucuronidation). The major metabolites excreted into the urine for both compounds were a labile N-conjugated metabolite (a postulated N-glucuronide) and a sulphated ring-hydroxylated metabolite (a postulated 4-amino-5-trifluoromethylphenyl sulphate) following dosing of 2-TFMA. These accounted for approximately 53.0 and 31.5% of the dose, respectively. This study identifies problems on sample component instability in the preparation and analysis procedures.

Less severe hypoglycaemia, better metabolic control, and improved quality of life in Type 1 diabetes mellitus with continuous subcutaneous insulin infusion (CSII) therapy; an observational study of 100 consecutive patients followed for a mean of 2 years

AIMS

To compare glycaemic control, occurrence of acute complications, and diabetes-specific quality of life in Type 1 diabetic patients (on intensified conventional insulin treatment (ICT)) before and after initiation of CSII.

METHODS

One hundred and three patients (58 women) started CSII between October 1995 and April 1999 in our department. The indication for CSII was optimization of metabolic control and improvement of flexibility of life style (OF group) in 60 patients (58%), and prevention of severe hypoglycaemia (HY group) in 43 patients. Mean age at initiation of CSII was 33 +/- 11 years (OF 33 +/- 10, HY 33 +/- 11 (mean +/- sd)), diabetes duration 18 +/- 9 years (OF 16 +/- 9, HY 20 +/- 9). Three patients stopped CSII, mean duration of CSII of the remaining 100 patients was 1.8 +/- 1.2 years. The occurrence of hypoglycaemia, ketoacidosis and skin abscesses was assessed retrospectively for the 12 months before starting CSII, and recorded continuously during CSII. Quality of life was assessed with a validated, diabetes-specific questionnaire before and after CSII in 50 patients.

RESULTS

The incidence of serious hypoglycaemia (any external help) was reduced from 1.23 (OF 0.0; HY 2.93) during ICT to 0.29 cases/patient per year (OF 0.09; HY 0.55) during CSII. The incidence of severe hypoglycaemia (SH) (treated with i.v. glucose or glucagon injection) fell from 0.70 (OF 0.0; SH 1.67) during ICT to 0.06 cases/patient per year (OF 0.02; HY 0.12) during CSII. HbA1c improved from 7.7 +/- 1.1% to 7.2 +/- 1.0% (P < 0.001) (OF 7.8% vs. 7.2%; HY 7.6% vs. 7.2%). During CSII the incidence of abscesses was 0.11 and of ketoacidosis 0.01 cases/patient per year. Quality of life assessments showed significant improvement in all parameters during CSII.

CONCLUSIONS

In our cohort of Type 1 diabetic patients, we observed a substantial decrease of hypoglycaemia along with a significant fall of HbA1c. Quality of life on CSII was improved when compared with ICT.

The metabolism of 4-trifluoromethoxyaniline and [13C]-4-trifluoromethoxyacetanilide in the rat: detection and identification of metabolites excreted in the urine by NMR and HPLC-NMR

A combination of 19F, 1H NMR and HPLC-NMR spectroscopic approaches have been used to quantify and identify the urinary-excreted metabolites of 4-trifluoromethoxyaniline (4-TFMeA) and its [13C]-labelled acetanilide following i.p. administration at 50 mg/kg to rats. The major metabolite excreted in the urine for both compounds was a sulphated ring-hydroxylated metabolite (either 2- or 3-trifluoromethyl-5-aminosulphate) which accounted for approximately 32.3% of the dose following the administration of 4-TFMeA and approximately 29.9% following dosing of the acetanilide. The trifluoromethoxy-substituent appeared to be metabolically stable, with no evidence of O-detrifluoromethylation. There was no evidence of the excretion of N-oxanilic acids in urine, of the type seen with 4-trifluoromethylaniline.

Separation of structural components in soil organic matter by diffusion ordered spectroscopy

Diffusion ordered spectroscopy (DOSY) was applied to two extracts of organic matter from the surface horizon of an oak forest soil. It was possible to identify and confirm the presence of numerous aliphatic, aromatic, sugar, and amino acid components that could be separated on the basis of diffusion in DMSO-d6 and D2O. On average, sugar components were identified as the largest molecules in solution, with molecular masses up to approximately 1500 Da followed by the aliphatic and aromatic components. Amino acids with a range of molecular weights were also identified in the mixture. The summation of the individual slices from the DOSY experiment closely resembles the conventional 1H spectra of the material, indicating that the components identified with DOSY represent all the components present in the mixture. The separation of components in the mixture in organic solvent supports new findings that fulvic and humic acids are not cross-linked, high molecular weight macromolecules but are instead aggregates composed of relatively simple molecules that take on colloidal properties in the presence of metal ions in aqueous solution. Using the knowledge that these organic mixtures are combinations of relatively simple entities with well-documented reactivities and behavior will improve our ability to predict and model their interactions and fate under natural conditions.

beta-Ureidopropionase deficiency: a novel inborn error of metabolism discovered using NMR spectroscopy on urine

In this work, NMR investigations that led to the discovery of a new inborn error of metabolism, beta-ureidopropionase (UP) deficiency, are reported. 1D (1)H-NMR experiments were performed using a patient's urine. 3-Ureidopropionic acid was observed in elevated concentrations in the urine spectrum. A 1D (1)H-(1)H total correlation spectroscopy (TOCSY) and two heteronuclear 2D NMR techniques (heteronuclear multiple bond correlation (HMBC) and heteronuclear single-quantum correlation (HSQC)) were used to identify the molecular structure of the compound that caused an unknown doublet resonance at 1.13 ppm. Combining the information from the various NMR spectra, this resonance could be assigned to 3-ureidoisobutyric acid. These observations suggested a deficiency of UP. With 1D (1)H-NMR spectroscopy, UP deficiency can be easily diagnosed. The (1)H-NMR spectrum can also be used to diagnose patients suffering from other inborn errors of metabolism in the pyrimidine degradation pathway.

The application of 1H HR-MAS NMR spectroscopy for the study of structures and associations of organic components at the solid-aqueous interface of a whole soil

High resolution-magic angle spinning nuclear magnetic resonance (HR-MAS NMR) allows the application of solution-state NMR experiments to samples that are not fully soluble and contain solids. Only the species in contact with the solvent system employed become NMR observable. In this study utilizing D2O as the solvent system we show it is possible to examine the structures at the solid-aqueous interface of a whole soil. Combining one- and two-dimensional HR-MAS NMR allowed, for the first time, the identification of fatty acids, aliphatic esters, and ethers/ alcohols as prominent species at the solid-aqueous interface of the soil with signals from sugars and amino acids also apparent. Few, if any signals from aromatic protons were observed when the soil was swollen in aqueous media, although these signals are observed in extracts from the same soil and when the soil is swollen with a more penetrating solvent(DMSO-d6)which is known to disassociate hydrogen bonds. These findings indicate that the soil aromatic moieties are protected in hydrophobic regions which are not water accessible. Furthermore, when the soil was amended with a herbicide (trifluralin), direct observations of interactions between the protons on a xenobiotic and the surrounding soil matrix were possible for the first time. HR-MAS promises to be a method that can be widely applicable to a range of complex environmental samples without the need for extraction, pretreatment, or purification.

Unchanged incidence of lower-limb amputations in a German City, 1990-1998

OBJECTIVE

A reduction of diabetes-related amputations by at least one-half within 5 years was declared a primary objective for Europe (St. Vincent Declaration, 1989). We collected data about incidence rates of amputations in one German city (Leverkusen, with a population of approximately 160,000 inhabitants) between 1990 and 1998 to ascertain a potential change in rates of incidence.

RESEARCH DESIGN AND METHODS

From all three hospitals in Leverkusen, we obtained complete lists of lower-limb amputations. From each patient record, diabetic status was determined. Only the first observed amputation was counted for the analysis. We estimated incidence rates of amputations in the entire population, the diabetic population, and the nondiabetic population. To test for time trend, we fitted Poisson regression models, adjusting for age and sex.

RESULTS

During, the defined period (the years 1990, 1991, and 1994-1998), 339 patients (all residents of Leverkusen) without previous amputations had nontraumatic lower-limb amputations. Of all subjects. 46% were female. Moreover, 76% of the subjects were known to have diabetes. Mean age was 71.3 years. Incidence rates in the diabetic population (standardized to the estimated German diabetic population, per 100,000 person-years) were as follows: 1990, 549; 1991, 356; 1994, 544; 1995, 386; 1996, 426; 1997, 433; and 1998, 463. The Poisson models showed no significant change of incident amputations over time in the diabetic population or in the nondiabetic population.

CONCLUSIONS

Beyond random variation, no change of incidence rates could be observed over the past 9 years. More specific interventions are needed to achieve a substantial reduction of diabetes-related amputations.

High-resolution (1)H NMR and magic angle spinning NMR spectroscopic investigation of the biochemical effects of 2-bromoethanamine in intact renal and hepatic tissue

The metabolic consequences of xenobiotic-induced toxicity were investigated using high-resolution magic angle spinning (MAS) NMR spectroscopy of intact tissue. Renal papillary necrosis (RPN) was induced in Sprague-Dawley rats (n = 12) via a single i.p. dose of 250 mg/kg 2-bromoethanamine (BEA) hydrobromide. At 2, 4, 6, and 24 h after treatment with BEA, three animals were killed and tissue samples were obtained from liver, renal cortex, and renal medulla. Tissue samples were also removed at 2 and 24 h from matched controls (n = 6). (1)H MAS NMR spectroscopic techniques were used to analyze samples of intact tissue ( approximately 10 mg). Decreased levels of nonperturbing renal osmolytes (glycerophosphocholine, betaine, and myo-inositol) were observed in the renal papilla of BEA-treated animals at 6 and 24 h postdose (p.d.), concomitant with a relative increase in the tissue concentration of creatine. Increased levels of glutaric acid were found in all tissues studied in BEA-treated animals at 4 and 6 h p.d., indicating the inhibition of mitochondrial fatty acyl CoA dehydrogenases and mitochondrial dysfunction. Increased levels of trimethylamine-N-oxide occurred in the renal cortex at 6 h p.d. Changes in the metabolite profile of liver included an increase in the relative concentrations of triglycerides, lysine, and leucine. The novel application of (1)H MAS NMR to the biochemical analysis of intact tissues following a toxic insult highlights the potential of this technique as a toxicological probe in providing a direct link between urinary biomarkers of toxicity and histopathological evaluation of toxicological lesions.

A high resolution (1)H magic angle spinning NMR study of a high-M(r) subunit of wheat glutenin

This work describes the application of (1)H magic angle spinning (MAS) nmr to the study of hydrated 1Dx5 wheat high-M(r) subunit. 1Dx5 is a water-insoluble 88 kDa protein, associated with good baking performance, and whose structure in the solid and low-hydration states is not known. High-resolution MAS (HR-MAS) results in a threefold resolution improvement of the (1)H spectra of the hydrated wheat protein, compared to standard MAS. The spectral resolution achieved enables, for the first time, two-dimensional nmr methods to be employed for the study of hydrated 1Dx5 and the assignment of the spectrum to be carried out on the basis of total correlated spectroscopy and (13)C/(1)H correlation experiments. Considerable shifts are observed for some resonances, relative to the chemical shifts of amino acids in solution, indicating that specific interactions occur in the hydrated protein network. Two main environments are identified for glutamine residues, Q(1) and Q(2), and these were characterized in terms of possible conformation and relative dynamics, with the basis of comparison between the single 90 degrees spectrum and the Carr-Purcel-Heiboom-Gill (CPMG) spectrum. The Q(1) residues are proposed to be situated in protein segments that adopt the beta-sheet conformation and that remain relatively hindered, possibly by hydrogen bonds involving the glutamine amide groups. On the other hand, Q(2) residues are proposed to be situated in a more mobile environment, adopting a looser conformation, possibly a beta-turn conformation. Based on the proximity of the Q(2) residues with glycine residues, as viewed by the nuclear Overhauser effect spectroscopy experiment, it is proposed that the protein segments that form the more mobile (or loop) sections of the network are rich in both glutamine and glycine residues.

Ethnic differences in insulinemia and sympathetic tone as links between obesity and blood pressure

Hyperinsulinemia and increased sympathetic nervous system (SNS) activity are thought to be pathophysiological links between obesity and hypertension. In the present study, we examined the relation among heart rate (HR), blood pressure (BP), and percent body fat (hydrodensitometry or DEXA), fasting plasma insulin concentration, and muscle sympathetic nerve activity (MSNA, microneurography) in male, normotensive whites (n=42) and Pima Indians (n=77). Pima Indians have a high prevalence of obesity and hyperinsulinemia but a relatively low prevalence of hypertension. Compared with whites, Pima Indian men had a higher percent body fat (28% versus 21%) and higher fasting insulin concentrations (210 versus 132 pmol/L) but lower MSNA (27 versus 33 bursts/min) (all P<0.001). In both ethnic groups, HR and BP were positively related to percent body fat and MSNA, and both were significant independent determinants of HR and BP in multiple regression analyses. However, MSNA was positively related to percent body fat and the fasting insulin concentration in whites (r=0.60 and r=0.47, both P<0.01) but not in Pima Indians (r=0.15 and r=0.03, NS) (P<0.01 for ethnic differences in the slope of the regression lines). These results confirm the physiological importance of the SNS in normal BP regulation but indicate that the roles of hyperinsulinemia and increased SNS activity as mediators for the relation between obesity and hypertension can differ between different ethnic groups. The lack of an increase in SNS activity with increasing adiposity and insulinemia in Pima Indians may contribute to the low prevalence of hypertension in this population.

High-resolution (1)H and (1)H-(13)C magic angle spinning NMR spectroscopy of rat liver

High-resolution magic angle spinning (MAS) (1)H NMR spectra of small samples (ca. 8 mg) of intact rat liver are reported for the first time. One dimensional spectra reveal a number of large well-resolved NMR signals mainly from low to medium molecular weight compounds (generally <1000 Daltons) from a variety of chemical classes. A range of 2D MAS-NMR experiments were performed, including (1)H J-resolved (JRES), (1)H-(1)H total correlation spectroscopy (TOCSY) and (1)H-(13)C heteronuclear multiple quantum coherence (HMQC) to enable detailed signal assignment. Resonances were assigned from alpha- and beta-glucose, glycerol, alanine, glutamate, glycine, dimethylglycine, lysine, and threonine, together with phosphocholine, choline, lactate, trimethylamine-N-oxide (TMAO), and certain fatty acids. Well-resolved (1)H NMR signals from glycogen (poly 1-4 alpha-glucose) were observed directly in intact liver using MAS-NMR spectroscopy. In addition, the resonances from the glycogen C(1)H proton in alpha(1-->4) linked glucose units with either alpha(1-->4) units adjacent or alpha(1-->6) linked branches could be resolved in a high-resolution (1)H NMR experiment giving direct in situ information on the ratio of alpha(1-->4) to alpha(1-->6) units. This indicates that despite the relatively high MW (>1,000,000 Daltons) there is considerable segmental motion in the glycogen molecules giving long (1)H T(2) relaxation times. Magn Reson Med 44:201-207, 2000.