Tailoring the Photophysical Properties of a Homoleptic Iron(II) Tetra N-Heterocyclic Carbene Complex by Attaching an Imidazolium Group to the (C∧N∧C) Pincer Ligand─A Comparative Study

We here report the synthesis of the homoleptic iron(II) N-heterocyclic carbene (NHC) complex [Fe(miHpbmi)2](PF6)4 (miHpbmi = 4-((3-methyl-1H-imidazolium-1-yl)pyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)) and its electrochemical and photophysical properties. The introduction of the π-electron-withdrawing 3-methyl-1H-imidazol-3-ium-1-yl group into the NHC ligand framework resulted in stabilization of the metal-to-ligand charge transfer (MLCT) state and destabilization of the metal-centered (MC) states. This resulted in an improved excited-state lifetime of 16 ps compared to the 9 ps for the unsubstituted parent compound [Fe(pbmi)2](PF6)2 (pbmi = (pyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)) as well as a stronger MLCT absorption band extending more toward the red spectral region. However, compared to the carboxylic acid derivative [Fe(cpbmi)2](PF6)2 (cpbmi = 1,1'-(4-carboxypyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)), the excited-state lifetime of [Fe(miHpbmi)2](PF6)4 is the same, but both the extinction and the red shift are more pronounced for the former. Hence, this makes [Fe(miHpbmi)2](PF6)4 a promising pH-insensitive analogue of [Fe(cpbmi)2](PF6)2. Finally, the excited-state dynamics of the title compound [Fe(miHpbmi)2](PF6)4 was investigated in solvents with different viscosities, however, showing very little dependency of the depopulation of the excited states on the properties of the solvent used.

Loss-of-function variant in chymotrypsin like elastase 3B (CELA3B) is associated with non-alcoholic chronic pancreatitis

BACKGROUND

Genetic alterations in digestive enzymes have been associated with chronic pancreatitis (CP). Recently, chymotrypsin like elastase 3B (CELA3B) emerged as a novel risk gene. Thus, we evaluated CELA3B in two European cohorts with CP.

METHODS

We analyzed all 8 CELA3B exons in 550 German non-alcoholic CP (NACP) patients and in 241 German controls by targeted DNA sequencing. In addition, we analyzed exons 6 and 7 by Sanger sequencing and the c.129+1G>A variant by melting curve analysis in 1078 further German controls. As replication cohort, we investigated up to 243 non-German European NACP patients and up to 1665 controls originating from Poland, Hungary, and Sweden. We assessed the cellular secretion and the elastase activity of recombinant CELA3B variants.

RESULTS

In the German discovery cohort, we detected a splice-site variant in intron 2, c.129+1G>A, in 9/550 (1.64%) CP patients and in 5/1319 (0.38%) controls (P=0.007, OR=4.4, 95% CI=1.5-13.0). In the European replication cohort, this variant was also enriched in patients (9/178 [5.06%]) versus controls (13/1247 [1.04%]) (P=0.001, OR=5.1, 95% CI=2.1-12.0). We did not find the two previously reported codon 90 variants, p.R90C and p.R90L.

CONCLUSIONS

Our data indicate that CELA3B is a susceptibility gene for CP. In contrast to previous reports suggesting that increased CELA3B activity is associated with CP risk, the splice-site variant identified here is predicted to cause diminished CELA3B expression. How reduced CELA3B function predisposes to pancreatitis remains to be elucidated.

Variants in the pancreatic CUB and zona pellucida-like domains 1 (CUZD1) gene in early-onset chronic pancreatitis - A possible new susceptibility gene

OBJECTIVE

Non-alcoholic chronic pancreatitis (NACP) frequently develops in the setting of genetic susceptibility associated with alterations in genes that are highly expressed in the pancreas. However, the genetic basis of NACP remains unresolved in a significant number of patients warranting a search for further risk genes.

DESIGN

We analyzed CUZD1, which encodes the CUB and zona pellucida-like domains 1 protein that is found in high levels in pancreatic acinar cells. We sequenced the coding region in 1163 European patients and 2018 European controls. In addition, we analyzed 297 patients and 1070 controls from Japan. We analyzed secretion of wild-type and mutant CUZD1 from transfected cells using Western blotting.

RESULTS

In the European cohort, we detected 30 non-synonymous variants. Using different prediction tools (SIFT, CADD, PROVEAN, PredictSNP) or the combination of these tools, we found accumulation of predicted deleterious variants in patients (p-value range 0.002-0.013; OR range 3.1-5.2). No association was found in the Japanese cohort, in which 13 non-synonymous variants were detected. Functional studies revealed >50% reduced secretion of 7 variants, however, these variants were not significantly enriched in European CP patients.

CONCLUSION

Our data indicate that CUZD1 might be a novel susceptibility gene for NACP. How these variants predispose to pancreatitis remains to be elucidated.

Potentials in Li-Ion Batteries Probed by Operando Ambient Pressure Photoelectron Spectroscopy

The important electrochemical processes in a battery happen at the solid/liquid interfaces. Operando ambient pressure photoelectron spectroscopy (APPES) is one tool to study these processes with chemical specificity. However, accessing this crucial interface and identifying the interface signal are not trivial. Therefore, we present a measurement setup, together with a suggested model, exemplifying how APPES can be used to probe potential differences over the electrode/electrolyte interface, even without direct access to the interface. Both the change in electron electrochemical potential over the solid/liquid interface, and the change in Li chemical potential of the working electrode (WE) surface at Li-ion equilibrium can be probed. Using a Li₄Ti₅O₁₂ composite as a WE, our results show that the shifts in kinetic energy of the electrolyte measured by APPES can be correlated to the electrochemical reactions occurring at the WE/electrolyte interface. Different shifts in kinetic energy are seen depending on if a phase transition reaction occurs or if a single phase is lithiated. The developed methodology can be used to evaluate charge transfer over the WE/electrolyte interface as well as the lithiation/delithiation mechanism of the WE.

Probing Electrochemical Potential Differences over the Solid/Liquid Interface in Li-Ion Battery Model Systems

The electrochemical potential difference (Δμ̅) is the driving force for the transfer of a charged species from one phase to another in a redox reaction. In Li-ion batteries (LIBs), Δμ̅ values for both electrons and Li-ions play an important role in the charge-transfer kinetics at the electrode/electrolyte interfaces. Because of the lack of suitable measurement techniques, little is known about how Δμ̅ affects the redox reactions occurring at the solid/liquid interfaces during LIB operation. Herein, we outline the relations between different potentials and show how ambient pressure photoelectron spectroscopy (APPES) can be used to follow changes in Δμ̅_e over the solid/liquid interfaces operando by measuring the kinetic energy (KE) shifts of the electrolyte core levels. The KE shift versus applied voltage shows a linear dependence of ∼1 eV/V during charging of the electrical double layer and during solid electrolyte interphase formation. This agrees with the expected results for an ideally polarizable interface. During lithiation, the slope changes drastically. We propose a model to explain this based on charge transfer over the solid/liquid interface.

HIPPIE: a new platform for ambient-pressure X-ray photoelectron spectroscopy at the MAX IV Laboratory

HIPPIE is a soft X-ray beamline on the 3 GeV electron storage ring of the MAX IV Laboratory, equipped with a novel ambient-pressure X-ray photoelectron spectroscopy (APXPS) instrument. The endstation is dedicated to performing in situ and operando X-ray photoelectron spectroscopy experiments in the presence of a controlled gaseous atmosphere at pressures up to 30 mbar [1 mbar = 100 Pa] as well as under ultra-high-vacuum conditions. The photon energy range is 250 to 2200 eV in planar polarization and with photon fluxes >10¹² photons s^-1 (500 mA ring current) at a resolving power of greater than 10000 and up to a maximum of 32000. The endstation currently provides two sample environments: a catalysis cell and an electrochemical/liquid cell. The former allows APXPS measurements of solid samples in the presence of a gaseous atmosphere (with a mixture of up to eight gases and a vapour of a liquid) and simultaneous analysis of the inlet/outlet gas composition by online mass spectrometry. The latter is a more versatile setup primarily designed for APXPS at the solid-liquid (dip-and-pull setup) or liquid-gas (liquid microjet) interfaces under full electrochemical control, and it can also be used as an open port for ad hoc-designed non-standard APXPS experiments with different sample environments. The catalysis cell can be further equipped with an IR reflection-absorption spectrometer, allowing for simultaneous APXPS and IR spectroscopy of the samples. The endstation is set up to easily accommodate further sample environments.

European Guideline on IgG4-related digestive disease - UEG and SGF evidence-based recommendations

The overall objective of these guidelines is to provide evidence-based recommendations for the diagnosis and management of immunoglobulin G4 (IgG4)-related digestive disease in adults and children. IgG4-related digestive disease can be diagnosed only with a comprehensive work-up that includes histology, organ morphology at imaging, serology, search for other organ involvement, and response to glucocorticoid treatment. Indications for treatment are symptomatic patients with obstructive jaundice, abdominal pain, posterior pancreatic pain, and involvement of extra-pancreatic digestive organs, including IgG4-related cholangitis. Treatment with glucocorticoids should be weight-based and initiated at a dose of 0.6-0.8 mg/kg body weight/day orally (typical starting dose 30-40 mg/day prednisone equivalent) for 1 month to induce remission and then be tapered within two additional months. Response to initial treatment should be assessed at week 2-4 with clinical, biochemical and morphological markers. Maintenance treatment with glucocorticoids should be considered in multi-organ disease or history of relapse. If there is no change in disease activity and burden within 3 months, the diagnosis should be reconsidered. If the disease relapsed during the 3 months of treatment, immunosuppressive drugs should be added.

On the Backward Euler Approximation of the Stochastic Allen-Cahn Equation

We consider the stochastic Allen-Cahn equation perturbed by smooth additive Gaussian noise in a spatial domain with smooth boundary in dimension d ≤ 3, and study the semidiscretization in time of the equation by an implicit Euler method. We show that the method converges pathwise with a rate O(Δtγ) for any γ < ½. We also prove that the scheme converges uniformly in the strong Lp-sense but with no rate given.

SEI Formation and Interfacial Stability of a Si Electrode in a LiTDI-Salt Based Electrolyte with FEC and VC Additives for Li-Ion Batteries

An electrolyte based on the new salt, lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI), is evaluated in combination with nano-Si composite electrodes for potential use in Li-ion batteries. The additives fluoroethylene carbonate (FEC) and vinylene carbonate (VC) are also added to the electrolyte to enable an efficient SEI formation. By employing hard X-ray photoelectron spectroscopy (HAXPES), the SEI formation and the development of the active material is probed during the first 100 cycles. With this electrolyte formulation, the Si electrode can cycle at 1200 mAh g(-1) for more than 100 cycles at a coulombic efficiency of 99%. With extended cycling, a decrease in Si particle size is observed as well as an increase in silicon oxide amount. As opposed to LiPF6 based electrolytes, this electrolyte or its decomposition products has no side reactions with the active Si material. The present results further acknowledge the positive effects of SEI forming additives. It is suggested that polycarbonates and a high LiF content are favorable components in the SEI over other kinds of carbonates formed by ethylene carbonate (EC) and dimethyl carbonate (DMC) decomposition. This work thus confirms that LiTDI in combination with the investigated additives is a promising salt for Si electrodes in future Li-ion batteries.

Electric Potential Gradient at the Buried Interface between Lithium-Ion Battery Electrodes and the SEI Observed Using Photoelectron Spectroscopy

The buried interface between the bulk electrode material and the solid electrolyte interphase (SEI) in cycled Li-ion battery anodes is suggested to incorporate an electric potential gradient. This suggestion is based on photoelectron spectroscopy (PES) results from different anode materials that all show relative binding energy shifts between the components of the SEI and the active anode. Implications of this electric potential gradient on binding energy reference points in PES as well as on charge-transfer kinetics in Li-ion batteries are discussed. Specifically, we show that the separation of surface layer and bulk material spectral contributions (depth profiling) is crucial for consistent data interpretation. We conclude that previous interpretations of lithiation as cause for changes in PES spectra may need to be revised.

Efficacy and safety of granulocyte, monocyte/macrophage adsorptive in pediatric ulcerative colitis

AIM: To investigate efficacy and safety for granulocyte, monocyte apheresis in a population of pediatric patients with ulcerative colitis.

METHODS: The ADAPT study was a prospective, open-label, multicenter study in pediatric patients with moderate, active ulcerative colitis with pediatric ulcerative colitis activity index (PUCAI) of 35-64. Patients received one weekly apheresis with Adacolumn^® granulocyte, monocyte/macrophage adsorptive (GMA) apheresis over 5 consecutive weeks, optionally followed by up to 3 additional apheresis treatments over 3 consecutive weeks. The primary endpoint was the change in mean PUCAI between baseline and week 12; the secondary endpoint was improvement in PUCAI categorized as (Significant Improvement, PUCAI decrease of ≥ 35), Moderate Improvement (PUCAI decrease of 20 < 35), Small Improvement (PUCAI decrease of 10 < 20) or No change (PUCAI decrease of < 10).

RESULTS: Twenty-five patients (mean age 13.5 years; mean weight 47.7 kg) were enrolled. In the intention-to-treat set (ITT), the mean value for PUCAI improvement was 22.3 [95%CI: 12.9-31.6; n = 21]. In the per-protocol (PP) set, the mean improvement was 36.3 [95%CI: 31.4-41.1; n = 8]. Significant Improvement was recorded for 9 out of 20 patients (45%); 5 out of 20 patients (25%) had Moderate Improvement and one patient (5%) had No Change in PUCAI score at week 12. In the PP set, six out of eight patients (75%) showed Significant Improvement; and in two out of eight patients (25%) Moderate Improvement was recorded. The endoscopic activity index (EAI) decreased by 3 points on average. Seven (7) out of 21 (33%) patients in ITT and 4 out of 8 (50%) patients in PP have used steroids during the clinical investigation. The mean steroid dosage for these patients in the ITT set decreased from a mean 12.4 mg to 10 mg daily on average from Baseline to week 12.

CONCLUSION: Adacolumn^® GMA apheresis treatment was effective in pediatric patients with moderate active Ulcerative Colitis. No new safety signals were reported. The present data contribute to considering GMA apheresis as a therapeutic option in pediatric patients having failed first line therapy.

Successful Hematopoietic Stem Cell Transplantation in a Patient with LPS-Responsive Beige-Like Anchor (LRBA) Gene Mutation

PURPOSE

Autosomal recessive mutations in LRBA, encoding for LPS-responsive beige-like anchor protein, were described in patients with a common variable immunodeficiency (CVID)-like disease characterized by hypogammaglobulinemia, autoimmune cytopenias, and enteropathy. Here, we detail the clinical, immunological, and genetic features of a patient with severe autoimmune manifestations.

METHODS

Whole exome sequencing was performed to establish a molecular diagnosis. Evaluation of lymphocyte subsets was performed for immunological characterization. Medical files were reviewed to collect clinical and immunological data.

RESULTS

A 7-year-old boy, born to consanguineous parents, presented with autoimmune hemolytic anemia, hepatosplenomegaly, autoimmune thyroiditis, and severe autoimmune gastrointestinal manifestations. Immunological investigations revealed low immunoglobulin levels and low numbers of B and NK cells. Treatment included immunoglobulin replacement and immunosuppressive therapy. Seven years after disease onset, the patient developed severe neurological symptoms resembling acute disseminated encephalomyelitis, prompting allogeneic hematopoietic stem cell transplantation (HSCT) with the HLA-identical mother as donor. Whole exome sequencing of the patient uncovered a homozygous 1 bp deletion in LRBA (c.7162delA:p.T2388Pfs*7). Importantly, during 2 years of follow-up post-HSCT, marked clinical improvement and recovery of immune function was observed.

CONCLUSIONS

Our data suggest a beneficial effect of HSCT in patients with LRBA deficiency.

Acute pancreatitis as a complication of childhood cancer treatment

Acute pancreatitis (AP) is now well recognized as a possible complication of childhood cancer treatment, interrupting the chemotherapy regimen, and requiring prolonged hospitalization, possibly with intensive care and surgical intervention, thereby compromising the effect of chemotherapy and the remission of the underlying malignant disease. This review summarizes the current literature and presents the various etiological factors for AP during chemotherapy as well as modern trends in the diagnosis and therapy of AP in children.

Conservative treatment of chronic pancreatitis

BACKGROUND

Chronic pancreatitis is a progressive inflammatory disease giving rise to several complications that need to be treated accordingly. Because pancreatic surgery has significant morbidity and mortality, less invasive therapy seems to be an attractive option.

AIM

This paper reviews current state-of-the-art strategies to treat chronic pancreatitis without surgery and the current guidelines for the medical therapy of chronic pancreatitis.

RESULTS

Endoscopic therapy of complications of chronic pancreatitis such as pain, main pancreatic duct strictures and stones as well as pseudocysts is technically feasible and safe. The long-term outcome, however, is inferior to definitive surgical procedures such as resection or drainage. On the other hand, the medical therapy of pancreatic endocrine and exocrine insufficiency is well established and evidence based.

CONCLUSIONS

Endoscopic therapy may be an option to bridge for surgery and in children/young adolescents and those unfit for surgery. Pain in chronic pancreatitis as well as treatment of pancreatic exocrine insufficiency follows established guidelines.

Echocardiography Can Identify Patients With Increased Pulmonary Vascular Resistance by Assessing Pressure Reflection in the Pulmonary Circulation

Background—

Pulmonary hypertension is a frequent finding in patients with cardiopulmonary disorders. It is important to recognize pulmonary hypertension due to increased pulmonary vascular resistance (PVR), as this affects treatment and prognosis. Patients with increased PVR have an increased pulmonary pressure reflection. We hypothesized that pressure reflection can be described by echocardiography and that variables related to pressure reflection can identify patients with increased PVR.

Methods and Results—

The study comprised 98 patients investigated within 24 hours of right heart catheterization and 20 control subjects. The pressure reflection variables were obtained by pulsed Doppler in the pulmonary artery and continuous Doppler of tricuspid regurgitation. We selected 3 variables related to pressure reflection: the interval from valve opening to peak velocity in the pulmonary artery (AcT, ms), the interval between pulmonary artery peak velocity and peak tricuspid velocity (tPV-PP, ms), and the right ventricular pressure increase after peak velocity in the pulmonary artery (augmented pressure, AP, mm Hg). The correlation between simultaneous catheter- and echocardiography-determined AP was strong (n=19, R =0.83). The AcT, tPV-PP, and AP in patients with a PVR of >3 Woods units (n=71) was (mean±SD) 77±16 ms, 119±36 ms, and 22±12 mm Hg, respectively, and differed from patients with a PVR of ≤3 Woods units (n=27, P <0.0001), 111±32 ms, 39±54 ms, and 3±4 mm Hg, and from controls, 153±32 ms, −19±45 ms, and 0 mm Hg, respectively ( P <0.0001). The AcT, tPV-PP, and AP values were not correlated with capillary wedge pressure ( R =0.08–0.16). The areas under the receiver operator characteristic curve (95%CI) for AcT, tPV-PP, and AP were 0.87 (0.82 to 0.95), 0.94 (0.89 to 0.99), and 0.98 (0.95 to 1.0), respectively.

Conclusions—

In this study, we describe a novel echocardiography method for assessing pressure reflection in the pulmonary circulation. This method can be used to identify patients with pulmonary hypertension due to increased PVR.

Granulocyte-monocyte adsorptive apheresis in pediatric inflammatory bowel disease: results, practical issues, safety, and future perspectives

BACKGROUND

The purpose of the study was to collect data on granulocyte-monocyte adsorptive apheresis (GMA) for the treatment of corticosteroid-dependent (SD) or corticosteroid-resistant (SR) inflammatory bowel disease (IBD) in children from 3 Nordic countries to evaluate its efficacy and safety and to assess practical issues.

METHODS

Retrospective data on 37 children treated with GMA were collected. In all, 22 children had ulcerative colitis (UC), 13 Crohn's disease (CD), and 2 had indeterminate colitis (IC). Their mean age was 13.2 years, range 5-17 years, and mean duration of disease was 2.4 years, range 1 month to 6 years. Indication for treatment in the UC group was SD in 11 cases, SR in 6 cases, and other reasons in 5 cases. The corresponding numbers in the CD group were SD in 8 cases, SR in 2 cases, and other reasons in 3 cases. In the IC group, 1 had SD and 1 was refractory to steroids, azathioprine, and infliximab. Efficacy was evaluated by severity indices: the Pediatric Ulcerative Colitis Activity Index (PUCAI) and the Pediatric Crohn's Disease Activity Index (PCDAI) and tapering of corticosteroids.

RESULTS

PUCAI and PCDAI decreased significantly in both groups after 3 months (P = 0.0007, P = 0.025). The dosage of corticosteroid was significantly reduced in the UC group by the end of GMA (P = 0.004) and this response continued after 3 months. Relapse was seen in 2 patients with UC and 3 patients with CD after 3 months follow-up.

CONCLUSIONS

GMA seems to be an effective and safe treatment in 81% of the SD or SR pediatric IBD patients, especially in those with UC.

A 2-yr national population study of pediatric ketoacidosis in Sweden: predisposing conditions and insulin pump use

The aim was to investigate triggering factors and insulin pump usage (continuous subcutaneous insulin infusion, CSII) at diabetic ketoacidosis (DKA). Data from 1999 and 2000 were collected retrospectively from Sweden. In 1999 and 2000, 7.4 and 11.0%, respectively, of children with diabetes used CSII. One hundred and forty-two episodes of DKA (pH < 7.30) were identified in 115 children (DKA at onset not included). Their hemoglobin A1c (HbA1c) was 10.1 +/- 2.0%, age 14.6 +/- 3.1 yr (range 1.5-19.9 yr), and diabetes duration 6.6 +/- 3.5 yr (range 0.4-17.7 yr). Fourteen persons (seven girls) had more than one episode of DKA. Reported causes of DKA were missed insulin doses (48.6%), gastroenteritis (14.1%), technical pump problems (12.7%), infection (13.4%), social problems (1.4%), unknown (5.6%), and not stated (4.2%). Alcohol was involved in eight episodes and drugs in one. Thirty of 115 patients (19 girls) used insulin pumps. The overall DKA incidence was 1.4/100 patient years in 1999 and 1.7/100 patient years in 2000. For insulin pump users, the DKA incidence was 3.2/100 patient years in 1999 and 3.6/100 patient years in 2000. HbA1c at DKA admission was lower for CSII users than patients who used injections (9.1 +/- 1.5 vs. 10.8 +/- 2.2%, p < 0.01), but pH and age did not differ. CSII had been used for 6 months (median) before the DKA episode. In conclusion, the DKA frequency in CSII users was approximately twice that of patients who used injections. Seventy-seven percent of the episodes occurred within 1 yr after CSII start. The high number of events reported to be caused by gastroenteritis is alarming because this may reflect a misinterpretation of DKA symptoms.

Cerebral venous thrombosis and heparin-induced thrombocytopenia in an 18-year old male with severe ulcerative colitis

The risk of thromboembolism is increased in inflammatory bowel disease and its symptoms may be overlooked. Furthermore, its treatment can be complex and is not without complications. We describe a case of an adolescent boy who developed a cerebral sinus venous thrombosis during a relapse of his ulcerative colitis and who, while on treatment with heparin, developed heparin-induced thrombocytopenia (HIT). The treatment was then switched to fondaparinux, a synthetic and selective inhibitor of activated factor X.

Diabetic ketoacidosis and cerebral oedema in Sweden--a 2-year paediatric population study

AIM

The aim of this study was to investigate diabetic ketoacidosis (DKA) and cerebral oedema in the Swedish paediatric diabetes population, and to measure laboratory parameters during treatment.

METHODS

The Swedish National Paediatric Diabetes Registry (SWEDIABKIDS) indicates that 16% of patients < 18 years during 2000 to 2004 had DKA at onset of diabetes. Data from 1999 and 2000 was collected retrospectively from all of Sweden by questionnaire.

RESULTS

We identified 292 cases of DKA (pH < 7.30) in 265 children (149 at diabetes onset), aged 0.8-19.9 years. The incidence of DKA in patients with previously diagnosed diabetes was 1.4/100 patient years in 1999 and 1.7/100 in 2000. Two patients, both 11 years old with newly diagnosed diabetes, had overt symptoms of cerebral oedema and one developed neurological sequelae. This corresponds to an incidence of 0.68% (2/292) with no mortality. Symptoms of subclinical cerebral oedema after admission (headache, vomiting, lethargy) were recorded in a further 16 cases. In two of these mannitol was given, and both recovered within 1-2 h. Laboratory data was available from 253/292 episodes. During treatment for DKA, hypokalaemia (< 3.5 mmol/l) was significantly more common at onset of diabetes than in patients with established diabetes (65 vs. 28%, P < 0.001; initial prescription of potassium was 20 mmol/l).

CONCLUSIONS

We conclude that 16% of children with new-onset diabetes presented with DKA at diagnosis and that the incidence of DKA in children with established diabetes was 1.6/100 patient years. Cerebral oedema occurred in 0.68% of the DKA episodes.

Evidence for different pharmacological targets for imidazoline compounds inhibiting settlement of the barnacleBalanus improvisus

We describe the effect of eight different imidazoline/guanidinium compounds on the settlement and metamorphosis of larvae of the barnacle Balanus improvisus. These agents were chosen on the basis of their similar pharmacological classification in vertebrates and their chemical similarity to medetomidine and clonidine, previously described as highly potent settlement inhibitors (nanomolar range). Seven of the tested compounds were found to inhibit settlement in a dose-dependent manner in concentrations ranging from 100 nM to 10 microM without any significant lethal effects. In vertebrate systems these substances have overlapping functions and interact with both alpha-adrenoceptors as well as imidazoline binding sites. Antagonizing experiments using the highly specific alpha(2)-antagonist methoxy-idazoxan or agmatine (the putative endogenous ligand at imidazoline receptors) were performed to discriminate between putative pharmacological mechanisms involved in the inhibition of cyprid settlement. Agmatine was not able to reverse the effect of any of the tested compounds. However, methoxy-idazoxan almost completely abolished the settlement inhibition mediated by guanabenz (alpha(2)-agonist, I(2) ligand), moxonidine (alpha(2)-agonist, I(1) ligand) and tetrahydrozoline (alpha-agonist, I(2) ligand). The actions of cirazoline (alpha(1)-agonist, I(2) ligand) BU 224 (I(2) ligand) and metrazoline (I(2) ligand) were not reversed by treatment with methoxy-idazoxan. These results suggest that the settlement inhibition evoked by the I(2) ligands and alpha(2)-agonists used in this study of the neurologically simple but well-organized barnacle larva is mediated through different physiological targets important in the overall settlement process.

Using chemometrics for navigating in the large data sets of genomics, proteomics, and metabonomics (gpm)

This article describes the applicability of multivariate projection techniques, such as principal-component analysis (PCA) and partial least-squares (PLS) projections to latent structures, to the large-volume high-density data structures obtained within genomics, proteomics, and metabonomics. PCA and PLS, and their extensions, derive their usefulness from their ability to analyze data with many, noisy, collinear, and even incomplete variables in both X and Y. Three examples are used as illustrations: the first example is a genomics data set and involves modeling of microarray data of cell cycle-regulated genes in the microorganism Saccharomyces cerevisiae. The second example contains NMR-metabonomics data, measured on urine samples of male rats treated with either of the drugs chloroquine or amiodarone. The third and last data set describes sequence-function classification studies in a set of G-protein-coupled receptors using hierarchical PCA.

Temporary preservation of beta-cell function by diazoxide treatment in childhood type 1 diabetes

OBJECTIVE

We examined the effect of diazoxide, an ATP-sensitive K(+) channel opener and inhibitor of insulin secretion, on beta-cell function and remission in children at clinical onset of type 1 diabetes.

RESEARCH DESIGN AND METHODS

A total of 56 subjects (21 girls and 35 boys, age 7-17 years) were randomized to 3 months of active treatment (diazoxide 5-7.5 mg/kg in divided doses) or placebo in addition to multiple daily insulin injections and were followed for 2 years.

RESULTS

Diazoxide decreased circulating C-peptide concentrations by approximately 50%. After cessation of the treatment, basal and meal-stimulated C-peptide concentrations increased to a maximum at 6 months, followed by a decline. Meal-stimulated C-peptide concentration was significantly higher at 12 months (0.43 +/- 0.22 vs. 0.31 +/- 0.26 nmol/l, P = 0.018) and tended to fall less from clinical onset to 24 months in the diazoxide- vs. placebo-treated patients (-0.05 +/- 0.24 vs. -0.18 +/- 0.26 nmol/l, P = 0.064). At 24 months, the meal-stimulated C-peptide concentrations were 0.24 +/- 0.20 and 0.20 +/- 0.17 nmol/l, respectively. Side effects of diazoxide were prevalent.

CONCLUSIONS

This study demonstrates that partial inhibition of insulin secretion for 3 months at onset of childhood type 1 diabetes suspends the period of remission and temporarily preserves residual insulin production. Further evaluation of the full potential of beta-cell rest will require compounds with less side effects as well as protocols optimized for sustained secretory arrest.

Megavariate analysis of hierarchical QSAR data

Multivariate PCA- and PLS-models involving many variables are often difficult to interpret, because plots and lists of loadings, coefficients, VIPs, etc, rapidly become messy and hard to overview. There may then be a strong temptation to eliminate variables to obtain a smaller data set. Such a reduction of variables, however, often removes information and makes the modelling efforts less reliable. Model interpretation may be misleading and predictive power may deteriorate. A better alternative is usually to partition the variables into blocks of logically related variables and apply hierarchical data analysis. Such blocked data may be analyzed by PCA and PLS. This modelling forms the base-level of the hierarchical modelling set-up. On the base-level in-depth information is extracted for the different blocks. The score vectors formed on the base-level, here called 'super variables', may be linked together in new matrices on the top-level. On the top-level superficial relationships between the X- and the Y-data are investigated. In this paper the basic principles of hierarchical modelling by means of PCA and PLS are reviewed. One objective of the paper is to disseminate this concept to a broader QSAR audience. The hierarchical methods are used to analyze a set of 10 haloalkanes for which K = 30 chemical descriptors and M = 255 biological responses have been gathered. Due to the complexity of the biological data, they are sub-divided in four blocks. All the modelling steps on the base-level and the top-level are reported and the final QSAR model is interpreted thoroughly.

Statistical molecular design of building blocks for combinatorial chemistry

The reduction of the size of a combinatorial library can be made in two ways, either base the selection on the building blocks (BB's) or base it on the full set of virtually constructed products. In this paper we have investigated the effects of applying statistical designs to BB sets compared to selections based on the final products. The two sets of BB's and the virtually constructed library were described by structural parameters, and the correlation between the two characterizations was investigated. Three different selection approaches were used both for the BB sets and for the products. In the first two the selection algorithms were applied directly to the data sets (D-optimal design and space-filling design), while for the third a cluster analysis preceded the selection (cluster-based design). The selections were compared using visual inspection, the Tanimoto coefficient, the Euclidean distance, the condition number, and the determinant of the resulting data matrix. No difference in efficiency was found between selections made in the BB space and in the product space. However, it is of critical importance to investigate the BB space carefully and to select an appropriate number of BB's to result in an adequate diversity. An example from the pharmaceutical industry is then presented, where selection via BB's was made using a cluster-based design.

[Measuring corneal thickness in photo-keratectomy with a reflectometry incorporated into the laser beam of the excimer laser]

PURPOSE

To integrate a newly developed OLCR instrument into the optical system of the excimer laser. The instrument is designed to perform corneal pachymetry before, during, and after corneal photoablation and thus allow for a precise and continuous on-line measurement of the corneal photoablation process.

METHODS

The conditions required to integrate the OLCR instrument into the excimer laser optics were investigated. With a technical setting providing on-line data of corneal thickness, three groups of 8-10 corneae received central keratectomies of 27 (group 1), 82 (group 2) and 163 (group 3) microns calculated central depth and 7.38 mm diameter. All measurements were performed with OLCR and ultrasound.

RESULTS

The OLCR instrument was coupled into the optical system of the excimer laser and a useful signal obtained at SLD power levels of 40 microW incident on the cornea. Individual corneal thickness measurements were obtained before, during and after the photoablation procedure. In group 1, the ablation was 50.3 (40-68) microns measured with ultrasound and 30.2 (27-38) microns measured with OLCR. In group 2, the ablation was 101.1 (80-113) microns measured with ultrasound and 93.3 (76-109) microns measured with OLCR. In group 3, the ablation was 210.6 (190-227) microns measured with ultrasound and 188.4 (181-197) microns measured with OLCR. The precision (standard deviation) for measurements of individual corneas was 1-2 microns with OLCR and up to 12 mm in Ultrasound measurements.

CONCLUSION

With this interferometric method, continuous, non-contact measurement of corneal thickness before, during and after excimer laser photoablation were performed. By establishing a feed-back control between the pachymetric measurements and the photoablation process, the precision of excimer ablation may possibly be further increased.

Toxicity in vitro of some silicon carbides and silicon nitrides: whiskers and powders

The objectives of this work were to investigate the toxicity of silicon carbide whiskers and powders and silicon nitride whiskers and powders and to compare their toxicity with the toxicity of crocidolite. The effects studied were inhibition of the cloning efficiency of V79 cells, formation of DNA strand breaks by means of a nick translation assay, formation of oxygen radicals in three different assays, and the ability to stimulate neutrophils to produce hydroxyl radicals. All materials showed concentration-dependent inhibition of the cloning efficiency of V79 cells. The inhibition by the most toxic whiskers was in the same order of magnitude as that of crocidolite. Milled whiskers and powders were less toxic than the whiskers. There was a high DNA breaking potential for crocidolite and four of the silicon carbide whiskers and a rather low one for the other materials. Formation of hydroxyl radicals was found for crocidolite and one of the silicon carbide whiskers. In the neutrophil activation test, there was a great variation in the different materials' abilities to activate neutrophils. There was also a good correlation between chemiluminescence and H2O2 formation. The highest activation was found in neutrophils exposed to two of the silicon carbide whiskers and one milled whisker. The conclusion of the investigation is that some of the ceramic materials studied had damaging biological effects comparable to or greater than those of crocidolite. The results from the investigation clearly imply that caution is needed in the introduction of new ceramic fiber materials, so that the correct precautions and protective devices are used in order to avoid harm to the personnel handling the material.

Modelling of the biological activity for a set of ceramic fibre materials: a QSAR study

The objective was to develop quantitative structure-activity relationships (QSARs) for a set of nine ceramic raw materials. The samples were characterized by a chemical analysis (both X-ray fluorescence and neutron activation analysis) and the morphology was determined by electron microscopy in combination with automated image analysis. Further, the fibre samples were subjected to two biological activity assays, measuring cytotoxicity and hydroxyl radical production. To investigate the produced data structures, principal component analysis (PCA) and partial least squares (PLS) were applied together with rigorous validation techniques. Significant QSARs were found for both biological activity assays. The morphology of the fibres plays an important role for the cytotoxicity and their trace element background is related to the hydroxyl radical production.

The influence of eye colour on susceptibility to TTS in humans

In order to investigate the function of the inner ear melanin, noise-induced temporary hearing loss (temporary threshold shift, TTS) was studied in humans with either blue or brown iris colour. Sixty-eight normally hearing teenage boys participated in this study. Hearing thresholds before and after exposure were established with a computerized sweep frequency audiometer in the frequency range 0.8-8 kHz. The noise exposure consisted of a 1/3 octave band-filtered noise with centre frequency 2 kHz at 105 dB SPL for 10 min. The mean TTS in the frequency range 2-8 kHz showed a significant difference with the brown-eyed subjects developing least TTS, and the blue-eyed subjects most TTS.

Minimum analogue peptide sets (MAPS) for quantitative structure-activity relationships

The information contents in previously published peptide sets was compared with smaller sets of peptides selected according to statistical designs. It was found that minimum analogue peptide sets (MAPS) constructed by factorial or fractional factorial designs in physiochemical properties contained substantial structure-activity information. Although five to six times smaller than the originally published peptide sets the MAPS resulted in QSAR models able to predict biological activity. The QSARs derived from a MAPS of nine dipeptides, and from a set of 58 dipeptides inhibiting angiotensin converting enzyme were compared and found to be of equal strength. Furthermore, for a set of bitter tasting dipeptides it was found that an incomplete MAPS of 10 dipeptides gave just as good a model as the model based on a set of 48 dipeptides. By comparison other non-designed sets of peptides gave QSARs with poor predictive power. It was also demonstrated how MAPS centered on a lead peptide can be constructed as to specifically explore the physiochemical and biological properties in the vicinity of the lead. It was concluded that small information-rich peptide sets MAPS can be constructed on the basis of statistical designs with principal properties of amino acids as design variables.

A multivariate representation and analysis of DNA sequence data

A new way to represent and analyze DNA sequence data is described. This approach complements methods currently used, in that it allows the systematic part of the variation between different sequences to be modeled. This can prove as informative as absence of variation (homology), which is the most widely used criterion for comparing sequence data. A multivariate sequence-activity model (SAM), for DNA-promoter sequences is presented, by which the relative promoter strength is modeled in terms of the primary DNA-sequence. The model is shown to have a good predictive capability. The coefficients from the model are interpreted, and used to design new structures predicted to be strong promoters in the system investigated. The approach described is also applicable to other kinds of sequence data, e.g. RNAs, proteins or peptides.

Analogy Models for Prediction of Human Toxicity

Estimating the toxicity to humans of chemicals by testing on human subjects is not considered to be ethically acceptable, and toxicity testing on laboratory animals is also questionable. Therefore, there is a need for alternative methods that will give estimates of various aspects of human toxicity. Batteries of in vitro tests, together with physicochemical and toxicokinetic data, analysed by efficient data analytical methods, may enable analogy models to be constructed that can predict human toxicity. It may be possible to model non-specific toxicity relating to lipophilicity, or basal cytotoxicity, for a series of diverse compounds with large variation in chemical structure and physicochemical properties. However, local models for a series of similar compounds are generally expected to be more accurate, as well as being capable of modelling more-specific interactions. Analogy models for the prediction of human toxicity are discussed and exemplified with physicochemical and cytotoxicity data from the first ten chemicals in the multicenter evaluation of in vitro cytotoxicity (MEIC) project.

Insulin sensitivity and glucose-induced insulin response changes during adolescence

Recently we reported that insulin resistance and glucose induced insulin release are inversely correlated to age in young healthy siblings of diabetic patients. To confirm this pattern of change with age, the subjects were reexamined after two years. The study was limited to the age groups with the lowest insulin sensitivity, i.e. 14.0-15.9 years for females and 16.0-17.9 years for males. All five girls and four of five boys showed an increased insulin sensitivity as measured by the somatostatin-insulin-glucose infusion test (p = 0.02). All subjects showed a decrease in fasting levels of insulin-like growth factor 1 (IGF-1) (p less than 0.01) during the observation period. All except one showed an increase in the levels of dehydroepiandrosterone sulphate (DHEA-S) (p less than 0.01). These data confirm that insulin sensitivity increases in the late teenage period. The parallelism to the changes of IGF-1 indicate that the pubertal changes in insulin sensitivity may partly be caused by growth hormone. Our data contradict the hypothesis that the low insulin sensitivity of puberty is due to the increased levels of DHEA-S.

A comparison of the variability in thresholds measured with insert and conventional supra-aural earphones

The purpose of this study was to evaluate the reliability and comparability of the commercially available insert earphone Etymotic Research ER-3A and the commonly available supra-aural TDH earphone. Thirteen subjects were tested five times with the ER-3A and five times with TDH-49P with MX-41/AR cushions. Threshold determinations were obtained utilizing a sweep-frequency audiometer in the range 0.25-8 kHz. The results showed that the reliability of the ER-3A earphone as measured by intra-individual variation, was comparable to that obtained with the TDH earphone. No evidence was found indicating an increased variability due to the positioning of the insert earphone's coupling device in the ear canal. Comparison of thresholds obtained with both devices indicated that the manufacturer's suggested correction values were appropriate.

The influence of inner ear melanin on susceptibility to TTS in humans

In order to investigate the function of the inner ear melanin, the relationship between skin pigmentation and noise-induced temporary hearing loss (TTS) was studied. Forty-four normal-hearing Caucasian subjects were divided into three groups according to their sun sensitivity. Hearing thresholds before and after exposure were ascertained with a computerized sweep frequency audiometer in the frequency range 2-8 kHz. The noise exposure consisted of a 1/3-octave band-filtered noise with a centre frequency of 2 kHz at 105 dB SPL for 10 min. The mean TTS in the frequency range 2-8 kHz showed statistically significant differences between the three groups, i.e. the most pigmented subjects developed least TTS, and the least pigmented subjects most TTS.

Peptide QSAR on substance P analogues, enkephalins and bradykinins containing L- and D-amino acids

Peptide QSARs are constructed for substance P analogues, enkephalins (two examples) and bradykinins containing both L- and D-amino acids. As descriptors in the QSARs, the previously developed descriptors z1 (hydrophobicity), z2 (bulk) and z3 (electronic effect) are used together with a qualitative variable coding for variation in chirality. Two parametrizations of the peptide sequences are tested. In the first no chiral description is used at all, and in the second chirality is described by the qualitative variable. It is concluded that for the current series of peptides, the biological response to variation in amino acid sequence and chirality can be modelled.

Elevated proinsulin in healthy siblings of IDDM patients independent of HLA identity

Based on the recent demonstration of elevated serum proinsulin levels in cystic fibrosis patients with impaired glucose tolerance, it was hypothesized that proinsulin could be an indicator of altered beta-cell function. We therefore analyzed fasting proinsulin levels in 99 siblings of insulin-dependent diabetes mellitus (IDDM) patients, most of them discordant for diabetes for greater than 6 yr. The results from this group were compared with the results from 41 healthy age- and sex-matched control subjects with no family history of diabetes. Median (range) fasting proinsulin in siblings was 8.9 pM (1.7-58 pM) vs. 3.8 pM (less than 1.2-28 pM) in control subjects (P less than .00001). There was no difference between the groups in fasting blood glucose concentrations. Both groups had fasting insulin concentrations within the normal range with a tendency toward lower values in the siblings: 108 pM (60-237 pM) vs. 118 pM (71-175 pM) (P = .07). The 99 siblings were subdivided into groups according to HLA sharing with their diabetic proband. The concentration of proinsulin, insulin, and blood glucose among the groups of 33 HLA-identical, 40 HLA-haploidentical, and 26 nonidentical siblings did not differ significantly. The fasting proinsulin level did not correlate with fasting levels of insulin, blood glucose, age, or body weight. We conclude that fasting proinsulin is elevated in healthy siblings of IDDM patients, whereas fasting insulin is normal or slightly decreased independent of HLA identity with their diabetic sibling. Elevated proinsulin levels could represent a family trait, perhaps mirroring a beta-cell more vulnerable to destruction, or it could reflect previous beta-cell damage that does not lead to IDDM.