Metformin treatment is associated with reduced risk of hypoglycaemia, major adverse cardiovascular events, and all-cause mortality in patients with post-pancreatitis diabetes mellitus: a nationwide cohort study

OBJECTIVE

Post-pancreatitis diabetes mellitus (PPDM) is a frequent complication of pancreatitis and is associated with an increased risk of adverse outcomes. Metformin is recommended for the treatment of PPDM, but evidence of its risk-benefit profile is limited. In a pharmaco-epidemiologic study, we investigated the association between metformin treatment and adverse outcomes in patients with PPDM.

DESIGN AND METHODS

In a Danish nationwide population-based cohort study, we included adults (≥18 years) with incident PPDM or type 2 diabetes between 2009 and 2018. Post-pancreatitis diabetes mellitus was categorised into acute and chronic subtypes (PPDM-A and PPDM-C). Associations between metformin treatment and severe hypoglycaemia, major adverse cardiovascular events (MACE), and all-cause mortality were examined across the diabetes subgroups using Cox regression analysis. Treatments with metformin, insulin, and other glucose-lowering therapies were handled as time-varying exposures.

RESULTS

We included 222 337 individuals with new-onset type 2 diabetes and 3781 with PPDM, of whom 2305 (61%) were classified as PPDM-A and 1476 (39%) as PPDM-C. Treatment with metformin was associated with a lower risk of severe hypoglycaemia (adjusted hazard ratio [HR] 0.41, 95% CI 0.27-0.62, P < .0001), MACE (HR 0.74, 95% CI 0.60-0.92, P = .0071), and all-cause mortality (HR 0.56, 95% CI 0.49-0.64, P < .0001) in patients with PPDM. In sensitivity analyses and among individuals with type 2 diabetes, metformin treatment exhibited comparable trends of risk reduction.

CONCLUSIONS

Metformin is associated with a lower risk of adverse outcomes, including all-cause mortality in patients with PPDM, supporting the use of metformin as a glucose-lowering therapy for these patients.

Using random forest machine learning on data from a large, representative cohort of the general population improves clinical spirometry references

INTRODUCTION

Spirometry is associated with several diagnostic difficulties, and as a result, misdiagnosis of chronic obstructive pulmonary disease (COPD) occurs. This study aims to investigate how random forest (RF) can be used to improve the existing clinical FVC and FEV1 reference values in a large and representative cohort of the general population of the US without known lung disease.

MATERIALS AND METHODS

FVC, FEV1, body measures, and demographic data from 23 433 people were extracted from NHANES. RF was used to develop different prediction models. The accuracy of RF was compared with the existing Danish clinical references, an improved multiple linear regression (MLR) model, and a model from the literature.

RESULTS

The correlation between actual and predicted FVC and FEV1 and the 95% confidence interval for RF were found to be FVC = 0.85 (0.85; 0.86) (p < 0.001), FEV1 = 0.92 (0.92; 0.93) (p < 0.001), and existing clinical references were FVC = 0.66 (0.64; 0.68) (p < 0.001) and FEV1 = 0.69 (0.67; 0.70) (p < 0.001). Slope and intercept for the RF models predicting FVC and FEV1 were FVC 1.06 and -238.04 (mL), FEV1: 0.86 and 455.36 (mL), and for the MLR models, slope and intercept were FVC: 0.99 and 38.56 39 (mL), and FEV1: 1.01 and -56.57-57 (mL).

CONCLUSIONS

The results point toward machine learning models such as RF have the potential to improve the prediction of estimated lung function for individual patients. These predictions are used as reference values and are an important part of assessing spirometry measurements in clinical practice. Further work is necessary in order to reduce the size of the intercepts obtained through these results.

Bone parameters in T1D and T2D assessed by DXA and HR-pQCT - A cross-sectional study: The DIAFALL study

INTRODUCTION/AIM

People with type 1 diabetes(T1D) and type 2 diabetes(T2D) have an increased risk of fractures due to skeletal fragility. We aimed to compare areal bone mineral density(aBMD), volumetric BMD(vBMD), cortical and trabecular measures, and bone strength parameters in participants with diabetes vs. controls.

METHODS

In a cross-sectional study, we included participants with T1D(n = 111), T2D(n = 106) and controls(n = 328). The study comprised of whole-body DXA and HR-pQCT scans, biochemistry, handgrip strength(HGS), Timed Up and GO(TUG), vibration perception threshold (VPT), questionnaires, medical histories, alcohol use, and previous fractures. Group comparisons were performed after adjustment for sex, age, BMI, diabetes duration, HbA1c, alcohol, smoking, previous fractures, postmenopausal, HGS, TUG, and VPT.

RESULTS

We found decreased aBMD in participants with T1D at the femoral neck(p = 0.028), whereas T2D had significantly higher aBMD at peripheral sites(legs, arms, p < 0.01) vs. controls. In T1D we found higher vBMD(p < 0.001), cortical vBMD (p < 0.001), cortical area(p = 0.002) and thickness(p < 0.001), lower cortical porosity(p = 0.008), higher stiffness(p = 0.002) and failure load(p = 0.003) at radius and higher vBMD(p = 0.003), cortical vBMD(p < 0.001), bone stiffness(p = 0.023) and failure load(p = 0.044) at the tibia than controls. In T2D we found higher vBMD(p < 0.001), cortical vBMD(p < 0.001), trabecular vBMD(p < 0.001), cortical area (p < 0.001) and thickness (p < 0.001), trabecular number (p = 0.024), lower separation(p = 0.010), higher stiffness (p < 0.001) and failure load (p < 0.001) at the radius and higher total vBMD(p < 0.001), cortical vBMD(p < 0.011), trabecular vBMD(p = 0.001), cortical area(p = 0.002) and thickness(p = 0.021), lower trabecular separation(p = 0.039), higher stiffness(p < 0.001) and failure load(p = 0.034) at tibia compared with controls.

CONCLUSION

aBMD measures were as expected but favorable bone microarchitecture and strength parameters were seen at the tibia and radius for T1D and T2D.

The incidence of fractures at various sites in newly treated patients with type 2 diabetes mellitus

Purpose

In this descriptive study, we examined the incidence of fractures in patients with newly treated type 2 diabetes mellitus (T2D) compared to matched reference population.

Methods

Participants from the UK Clinical Practice research datalink (CPRD) GOLD (1987-2017), aged ≥30 years, with a T2D diagnosis code and a first prescription for a non-insulin anti-diabetic drug (n = 124,328) were included. Cases with T2D were matched by year of birth, sex and practice to a reference population (n = 124,328), the mean follow-up was 7.7 years. Crude fracture incidence rates (IRs) and incidence rate ratios (IRRs) were calculated. Analyses were stratified by fracture site and sex and additionally adjusted for BMI, smoking status, alcohol use and history of any fracture at index date.

Results

The IR of all fractures and major osteoporotic fractures was lower in T2D compared to the reference population (IRR 0.97; 95%CI 0.94-0.99). The IRs were lower for clavicle (IRR 0.67; 0.56-0.80), radius/ulna (IRR 0.81; 0.75-0.86) and vertebral fractures (0.83; 0.75-0.92) and higher for ankle (IRR 1.16; 95%CI 1.06-1.28), foot (1.11; 1.01-1.22), tibia/fibula (1.17; 1.03-1.32) and humerus fractures (1.11; 1.03-1.20). Differences in IRs at various fracture sites between T2D and the reference population were more pronounced in women than in men. In contrast, BMI adjusted IRs for all fractures (IRR 1.07; 1.04-1.10) and most individual fracture sites were significantly higher in T2D, especially in women.

Conclusion

The crude incidence of all fractures was marginally lower in patients with newly treated T2D compared to the matched reference population but differed according to fracture site, especially in women. BMI adjusted analyses resulted in higher incidence rates in T2D at almost all fracture sites compared to crude incidence rates and this was more pronounced in women than in men. This implies that BMI may have a protective impact on the crude incidence of fractures, especially in women with newly treated T2D.

Risk of heart failure following short-term non-steroidal anti-inflammatory drug use in patients with type 2 diabetes mellitus

Background

Fluid retention is a known but underappreciated side-effect of non-steroidal anti-inflammatory drug (NSAID) use. As type 2 diabetes mellitus (T2DM) has been linked to both subclinical cardiomyopathy and a decline in kidney function, short-term NSAID use could lead to subsequently development of heart failure (HF) due to aberrations in fluid balances.

Purpose

We investigated associations between short-term NSAID use and the risk of HF in a nationwide cohort of patients with T2DM.

Methods

Using nationwide Danish registers, we identified patients diagnosed with T2DM during 1998–2018. Follow-up began 120 days after first-time T2DM diagnosis among patients without prior heart failure or a rheumatological diagnosis indicating long-term NSAID use.

To describe use of NSAID among patients with T2DM, we reported proportions of patients claiming at least 1, 2, 3 or 4 prescriptions of NSAID within one year of start of follow-up. We investigated associations between use of NSAIDs (celecoxib, diclofenac, ibuprofen and naproxen) and new-onset HF hospitalizations using a case-crossover design with 28-day exposure windows and reported odds ratios (OR) with 95% confidence intervals (CI). The case-crossover design uses each individual as his or her own control making it suitable to study the effect of short-term exposure on immediate events while mitigating unmeasured confounding. Sensitivity analyses using exposure windows of 14 and 42 days were performed as well.

Results

A total of 334,950 patients with T2DM was included (47.7% female, median age of 61 [interquartile range 50–70]). Celecoxib and naproxen were rarely used; on the contrary, prescriptions of diclofenac and ibuprofen were claimed at least once within one year from the beginning of follow-up by 4.9% and 15.5% of patients, respectively–0.9% and 2.7% claimed at least four prescriptions (Figure 1).

The risk of new-onset HF hospitalization was increased following use of diclofenac or ibuprofen with corresponding ORs of 1.3 (95% CI 1.0 to 1.7) and 1.3 (95% CI 1.1 to 1.5) using 28-day exposure windows. An increased risk following use of celecoxib or naproxen was not found (Figure 2).

Conclusion

NSAIDs diclofenac and ibuprofen were both widely used and associated with an increased risk of new-onset HF hospitalization in patients with T2DM. This suggests a previously unknown and serious, clinically relevant concern of NSAID use in patients with T2DM.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Ib Mogens Kristiansens Almene FondHelsefonden

Cardiovascular risk following cannabinoid treatment for patients with chronic pain

Background

Treatment with medical cannabis for chronic pain is in popular demand, and a rising number of countries allow physicians to prescribe medical cannabis for pain management. However, data on drug-safety is scarce. Studies have showed a risk of cardiovascular side effects following use of recreational cannabis warranting further investigations into the safety of prescribing medical cannabis.

Purpose

We investigated risk of new-onset arrhythmias (tachy- or bradyarrhythmia and conduction disorders), acute coronary syndrome (ACS) and heart failure (HF) following use of prescribed medical cannabis compared with no use in a nationwide cohort of patients with chronic pain.

Methods

Using nationwide Danish registers, a cohort of patients with chronic pain and without prior history of arrhythmias, ACS, HF or prescribed medical cannabis (cannabinoid, cannabidiol or dronabinol) use were followed from 2018–2021. Any patient from the cohort initiating first-time treatment with medical cannabis was identified and matched 1:10 to corresponding controls within the cohort using incidence density sampling. Matching parameters were age group, sex, and chronic pain diagnosis. Follow-up was initiated at the date of the first claimed prescription of medical cannabis or the corresponding date among controls. We reported 180-day standardized absolute risks (AR) with 95% confidence intervals (CI) and risk ratios (RR) from fitted multivariable logistic regression models comparing patients exposed to medical cannabis with patients not exposed. Separate analyses for each chronic pain group were conducted as well.

Results

Among 1.6 million patients with chronic pain, 4,562 patients claimed at least one prescription of medical cannabis (exposed) and were each matched to 10 controls (non-exposed). Exposed and non-exposed patients were identical in relation to matching parameters; however, exposed patients were slightly more comorbid, and a larger proportion was concomitantly treated with other pain medication (Table). The risk of new-onset arrhythmia was elevated among exposed patients with 180-day AR of 0.71% (95% CI 0.47%–0.94%) compared with 0.43% (95% CI 0.37%–0.49%) yielding a RR of 1.64 (95% CI 1.04–2.23). The risk of new-onset ACS and HF was not increased comparing exposed to non-exposed with corresponding 180-day ARs of 0.13% (95% CI 0.03%-0.23%) vs 0.11% (95% CI 0.08%–0.14% and 0.13% (95% CI 0.03%–0.24%) vs 0.14% (95% CI 0.11%–0.17% (corresponding RRs of 1.2 [95% CI 0.3–2.1] and 0.9 [95% CI 0.2–1.7]) (Figure). Subgroup analyses of each chronic pain group yielded similar results.

Conclusion

In a nationwide cohort of patients with chronic pain, use of medical cannabis was associated with a 64% risk increase of arrhythmias compared with no use. This poses a potential health concern and is vital knowledge for any physician prescribing medical cannabis. Use of medical cannabis was not associated with an elevated risk of ACS or HF.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Ib Mogens Kristiansens Almene FondHelsefonden

Risk of Major Adverse Cardiovascular Events, Severe Hypoglycemia, and All-Cause Mortality in Postpancreatitis Diabetes Mellitus Versus Type 2 Diabetes: A Nationwide Population-Based Cohort Study

OBJECTIVE

Postpancreatitis diabetes mellitus (PPDM) is a frequent complication of pancreatitis and associates with poor glycemic control. We investigated the risk of adverse diabetes-related outcomes in PPDM compared with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this Danish population-based cohort study, we included adults (>18 years) with incident PPDM or type 2 diabetes between 1998 and 2018 through national health registries. PPDM was further divided into acute (PPDM-A) and chronic (PPDM-C) subtypes. We ascertained risk of major adverse cardiovascular events (MACE), severe hypoglycemia, and all-cause mortality as well as incidence rates of severe hypoglycemia. We compared risk and incidence rates across diabetes subgroups using multivariate Cox and Poisson regression analyses.

RESULTS

We identified 383,325 people with incident type 2 diabetes, 3,418 with PPDM-A, and 2,461 with PPDM-C. Compared with type 2 diabetes, PPDM-C was associated with increased risks of severe hypoglycemia (hazard ratio [HR] 5.27, 95% CI 4.62-6.00, P < 0.001) and all-cause mortality (HR 1.54, 95% CI 1.45-1.64, P < 0.001). Similar patterns were observed for people with PPDM-A. Incidence rate ratios (IRRs) for severe hypoglycemia were increased in both PPDM-C (IRR 7.38, 95% CI 6.75-8.08, P < 0.001) and PPDM-A (IRR 3.76, 95% CI 3.36-4.21, P < 0.001) compared with type 2 diabetes. Findings were consistent in an analysis restricted to people on insulin and in an analysis including pancreatitis patients without diabetes as comparator group.

CONCLUSIONS

Compared with type 2 diabetes, PPDM is associated with excess risk of adverse diabetes-related outcomes. This has important implications for management.

The pattern of incident fractures according to fracture site in people with T1D

Higher incidences of fractures are seen in people with type 1 diabetes (T1D), but knowledge on different fracture sites is sparse. We found a higher incidence mainly for distal fracture sites in people with T1D compared to controls. It must be further studied which fractures attributed to the higher incidence rates (IRs) at specific sites.

INTRODUCTION

People with T1D have a higher incidence of fractures compared to the general population. However, sparse knowledge exists on the incidence rates of individual fracture sites. Therefore, we examined the incidence of various fracture sites in people with newly treated T1D compared to matched controls.

METHODS

All people from the UK Clinical Practice Research Datalink GOLD (1987-2017), of all ages with a T1D diagnosis code (n = 6381), were included. People with T1D were matched by year of birth, sex, and practice to controls (n = 6381). Fracture IRs and incidence rate ratios (IRRs) were calculated. Analyses were stratified by fracture site and sex.

RESULTS

The IR of all fractures was significantly higher in people with T1D compared to controls (IRR: 1.39 (CI95%: 1.24-1.55)). Compared to controls, the IRR for people with T1D was higher for several fracture sites including carpal (IRR: 1.41 (CI95%: 1.14-1.75)), clavicle (IRR: 2.10 (CI95%: 1.18-3.74)), foot (IRR: 1.70 (CI95%: 1.23-2.36)), humerus (IRR: 1.46 (CI95%: 1.04-2.05)), and tibia/fibula (IRR: 1.67 CI95%: 1.08-2.59)). In women with T1D, higher IRs were seen at the ankle (IRR: 2.25 (CI95%: 1.10-4.56)) and foot (IRR: 2.11 (CI95%: 1.27-3.50)), whereas in men with T1D, higher IRs were seen for carpal (IRR: 1.45 (CI95%: 1.14-1.86)), clavicle (IRR: 2.13 (CI95%: 1.13-4.02)), and humerus (IRR: 1.77 (CI95%: 1.10-2.83)) fractures.

CONCLUSION

The incidence of carpal, clavicle, foot, humerus, and tibia/fibula fractures was higher in newly treated T1D, but there was no difference at other fracture sites compared to controls. Therefore, the higher incidence of fractures in newly treated people with T1D has been found mainly for distal fracture sites.

Usage and risk with phosphodiesterase type 5 inhibitors in male patients with chronic ischemic heart disease on oral organic nitrates

Background

Combining oral organic nitrates (OON) with phosphodiesterase type 5 (PDE5) inhibitors is contraindicated. Growing and liberal use of PDE5 inhibitors for erectile dysfunction among patients with ischemic heart disease (IHD) could pose serious health consequences especially among patients with IHD on OON.

Purpose

We hypothesize that concomitant prescription of OON and PDE5 inhibitors is prevalent and has increased in recent years, and further that possible co-exposure could be associated with an increased risk of ischemic stroke, myocardial infarction (MI) or acute coronary angiography (CAG).

Methods

During 2000–2018, we included all male patients with history of IHD between 18 and 85 years of age from nationwide Danish health registers. Patients with a history of pulmonary hypertension were excluded and not followed up afterwards if they developed the condition during follow-up. From this cohort, we identified an OON treated subgroup defined by two consecutively redeemed prescriptions of OON within 180 days from each other. Further, to become a case or control, patients had to redeem a prescription of OON within 180 days prior to the event or corresponding date among controls.

Temporal trends during 2001–2018 of PDE5 inhibitor use were calculated among all male patients with IHD and the subgroup on OON. Among OON treated patients, we examined associations between PDE5 inhibitor use and risk of ischemic stroke, MI or CAG using a case-crossover design where each individual serves as his/her own control thereby controlling for time-invariant confounding. The case-crossover design compares an individual's exposure in an index period just before the event occurred to a reference period prior to the index period. We investigated periods of varying length (7, 14, 21 and 28 days). To account for possible temporal trends in the use of PDE5 inhibitors, we also conducted a case-time-control analysis using a control group matched on age and calendar year.

Results

We identified 249,541 male patients with IHD (median age 65 years [IQR 56–73]), and a subgroup of 42,073 (17%) on OON treatment (median age 70 years [IQR 62–77]). From 2001 to 2018, the use of PDE5 inhibitors saw a 6-fold increase among all male IHD patients and a 10-fold rise in the subgroup on OON (Figure 1). The risk of ischemic stroke, MI or CAG following exposure to PDE5 inhibitors was not increased in the OON subgroup in neither the case-crossover nor the case-time-control analyses (Figure 2).

Conclusions

The use of PDE5 inhibitors has increased 6-fold since 2001 among male patients with IHD, and 10-fold among patients on OON–notwithstanding an established absolute contraindication. However, we did not find any evidence of an increased risk of ischemic stroke, MI or acute CAG following exposure to PDE5 inhibitors in the OON subgroup. This suggests that patients on OON are adequately informed and comply with the recommended pause in OON medication prior to PDE5 inhibitor use.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Ib Mogens Kristiansens Almene FondandHelsefonden

Gastrointestinal bleeding risk following concomitant treatment with oral glucocorticoids in patients with atrial fibrillation on direct-acting oral anticoagulants

Background

Oral glucocorticoids and direct-acting oral anticoagulants (DOAC) have both been associated with a risk of gastrointestinal (GI) bleeding. However, drug safety, especially regarding the risk of bleeding, in relation to concomitant treatment with oral glucocorticoids and DOACs is insufficiently explored.

Purpose

We aimed to investigate the short-term risk of GI bleeding in patients with atrial fibrillation (AF) following concomitant treatment with DOACs and oral glucocorticoids.

Methods

Register-based, retrospective and nationwide Danish study including patients with AF and on DOAC treatment during 2012–2018. Patients were defined as exposed to oral glucocorticoids from the date of a redeemed prescription and 60 days forward. We associated concomitant treatment with GI bleeding and reported hazard ratios (HR) via a nested case-control design and standardized 60-day absolute risk adjusted for comorbidities using a cohort design. In both analyses, exposed were compared to non-exposed controls matched on age, sex, calendar year, follow-up time and DOAC agent.

Results

We included 98,376 patients (age [interquartile range]: 75 [68– 82], 44% females) with AF on DOAC treatment. The use of oral glucocorticoids among included patients was widespread with 16% redeeming at least one prescription within three years, 4% redeeming at least five (Figure 1A). Lung disease was the most frequent indication (Figure 1B). Concomitant treatment with DOACs and oral glucocorticoids was associated with an increased incidence of GI bleeding (total n=4,946) compared with only DOAC treatment, including a dose-response trend (&lt;20mg daily dose, HR [95% confidence interval (CI)]: 1.64 [1.38–1.95]; ≥20mg daily dose, HR [95% CI]: 2.29 [1.90–2.77]). Likewise, the standardized 60-day absolute risk of GI bleeding from first oral glucocorticoid exposure was increased compared with non-exposed (Figure 2).

Conclusion

Caution should be exercised when prescribing even short-term oral glucocorticoid treatment for DOAC treated patients, most notably in high doses and for patients with elevated bleeding risk.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Ib Mogens Kristiansens Almene FondandHelsefonden

Epidemiology of hypoglycaemic episodes leading to hospitalisations in Denmark in 1998-2018

AIMS/HYPOTHESIS

We aimed to investigate the nationwide trends in incidence and associated risk factors, with focus on blood glucose-lowering medication, for the first hypoglycaemic episode leading to hospitalisation in Denmark among people with type 1 and 2 diabetes mellitus.

METHODS

A cohort study of all people with diabetes from 1977 to 2018 experiencing hypoglycaemic episodes leading to hospitalisation in 1998-2018 was established. Data were extracted from the Danish National Patient Registry. Trends in incidence rates were investigated with Poisson regression models and linear regressions, and risk factors were investigated with Cox proportional hazards models.

RESULTS

A total of 66,438 hypoglycaemic episodes leading to hospitalisation in 1998-2018 was investigated among 641,402 people with type 1 (mean ± SD age 37 ± 22 years) and type 2 diabetes (mean ± SD age 61 ± 17 years). Between 2003 and 2018, the incidence rate fell by 66% for type 1 diabetes (incidence rate ratio [IRR] 0.34 [95% CI 0.31, 0.36], p < 0.0001) and 61% for type 2 diabetes (IRR 0.39 [95% CI 0.36, 0.42], p < 0.0001). With respect to hypoglycaemic episodes, insulin glargine (HR 1.20 [95% CI 1.05, 1.36], p = 0.0059), insulin detemir (HR 1.18 [95% CI 1.04, 1.32], p = 0.0077) and insulin degludec (HR 1.04 [95% CI 0.81,1.33], p = 0.7706) seemed safer than human insulin (long-acting insulin HR 1.38 [95% CI 1.25, 1.52], p < 0.0001; combination insulins HR 1.84 [95% CI 1.65, 2.05], p < 0.0001) and, especially, sodium-glucose cotransporter 2 inhibitors (HR 0.43 [95% CI 0.33, 0.56], p < 0.0001), glucagon-like peptide 1 receptor agonists (HR 0.51 [95% CI 0.44, 0.58], p < 0.0001) and dipeptidyl peptidase 4 inhibitors (HR 0.44 [95% CI 0.38, 0.49], p < 0.0001) seemed safer than sulfonylureas (HR 2.27 [95% CI 2.18, 2.37], p < 0.0001).

CONCLUSIONS/INTERPRETATION

Incidence rates of hypoglycaemic episodes leading to hospitalisation are declining in Denmark, and the advent of new treatment alternatives may play a significant role in this decline. From a safety perspective, these findings are important and should be considered by clinicians when assessing treatment options for patients.

Efficacy of the TMPRSS2 inhibitor camostat mesilate in patients hospitalized with Covid-19-a double-blind randomized controlled trial

BACKGROUND

The trans-membrane protease serine 2 (TMPRSS2) is essential for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cell entry and infection. Efficacy and safety of TMPRSS2 inhibitors in patients with coronavirus disease 2019 (Covid-19) have not been evaluated in randomized trials.

METHODS

We conducted an investigator-initiated, double-blind, randomized, placebo-controlled multicenter trial in patients hospitalized with confirmed SARS-CoV-2 infection from April 4, to December 31, 2020. Within 48 h of admission, participants were randomly assigned in a 2:1 ratio to receive the TMPRSS2 inhibitor camostat mesilate 200 mg three times daily for 5 days or placebo. The primary outcome was time to discharge or clinical improvement measured as ≥2 points improvement on a 7-point ordinal scale. Other outcomes included 30-day mortality, safety and change in oropharyngeal viral load.

FINDINGS

137 patients were assigned to receive camostat mesilate and 68 to placebo. Median time to clinical improvement was 5 days (interquartile range [IQR], 3 to 7) in the camostat group and 5 days (IQR, 2 to 10) in the placebo group (P = 0·31). The hazard ratio for 30-day mortality in the camostat compared with the placebo group was 0·82 (95% confidence interval [CI], 0·24 to 2·79; P = 0·75). The frequency of adverse events was similar in the two groups. Median change in viral load from baseline to day 5 in the camostat group was -0·22 log10 copies/mL (p <0·05) and -0·82 log10 in the placebo group (P <0·05).

INTERPRETATION

Under this protocol, camostat mesilate treatment was not associated with increased adverse events during hospitalization for Covid-19 and did not affect time to clinical improvement, progression to ICU admission or mortality. ClinicalTrials.gov Identifier: NCT04321096. EudraCT Number: 2020-001200-42.

Twenty years with diabetes and amputations: a retrospective population-based cohort study

AIM

To investigate the trends in non-traumatic lower limb amputation in people with and without diabetes.

METHODS

From the Danish National Patient Register, all people with either type 1 or type 2 diabetes (n = 462 743) as well as a group of people without diabetes from the general population (n = 1 388 886) were identified and separated into three groups based on diabetes type. Among these, 17 265 amputations were identified between 1997 and 2017 and stratified into trans-femoral amputations, trans-tibial amputations and amputations below the ankle using surgical codes. Annual changes were described using least-squares linear regression.

RESULTS

The yearly mean decrease in incidence rate of amputation per 1000 person-years was -0.032 [95% CI: -0.062, -0.001], -0.022 [-0.032, -0.012] and -0.006 [-0.009, -0.003] for trans-femoral amputation, -0.072 [-0.093, -0.052], -0.090 [-0.102, -0.078] and -0.015 [-0.016, -0.013] for trans-tibial amputation, and -0.055 [-0.080, -0.020], -0.075 [-0.090, -0.060] and -0.011 [-0.014, -0.007] for amputation below the ankle in people with type 1 diabetes, people with type 2 diabetes and people without diabetes, respectively.

CONCLUSIONS

Over recent decades, the incidence of amputation has decreased significantly in people with diabetes and in the general population without diabetes.

Prediction of Nocturnal Hypoglycemia From Continuous Glucose Monitoring Data in People With Type 1 Diabetes: A Proof-of-Concept Study

BACKGROUND

Intensive insulin therapy has documented benefits but may also come at the expense of a higher risk of hypoglycemia. Hypoglycemia is associated with higher all-cause mortality and nocturnal hypoglycemia has been associated with the sudden dead-in-bed syndrome. This proof-of-concept study sought to investigate if nocturnal hypoglycemia can be predicted.

METHOD

Continuous glucose monitoring, meal, insulin, and demographics data from 463 people with type 1 diabetes were obtained from a clinical trial. A total of 4721 nights without or with hypoglycemia (429) were available including data from three consecutive days before the night. Thirty-two features were calculated based on these data. Data were split into 20% participants for evaluation and 80% for training. The optimal feature subset was found from forward selection of the 80% participants with linear discriminant analysis as basis for the classifier.

RESULTS

The forward selection resulted in a feature subset of four features. The evaluation resulted in an area under the receiver operating characteristics curve (ROC-AUC) of 0.79 leading to a sensitivity and a specificity of, e.g., 75% and 70%.

CONCLUSIONS

It was possible to predict nocturnal hypoglycemic episodes with a ROC-AUC of 0.79. A warning at bedtime about nocturnal hypoglycemia could be of great help for people with diabetes to enable preventive actions. Further development of the proposed algorithm is needed for implementation in everyday practice.

Diabetes and fractures: new evidence of atypical femoral fractures?

Patients with diabetes have an increased risk of fractures. In this study, subtrochanteric and femoral shaft fractures were increased in patients with type 1 diabetes compared with the general population. In the light of this, more evidence points towards an association between diabetes and atypical femoral fractures.

INTRODUCTION

Patients with diabetes have an increased risk of femoral fractures, but little is known about the risk of atypical femoral fractures (AFFs). The aim of this study was to identify the risk of subtrochanteric and femoral shaft (ST/FS) fractures and estimate the risk of AFFs in patients with type 1 (T1D) and type 2 diabetes (T2D).

METHODS

From the nationwide Danish National Patient Register, we identified patients with T1D (n = 19,896), T2D (n = 312,188), and sex- and aged-matched controls without diabetes (n = 996,252) from the general population and all ST/FS fractures (n = 7509). Data were analyzed using a Cox proportional-hazards model and the incidence rate and rate ratio of ST/FS fractures were estimated.

RESULTS

The incidence rate of ST/FS fractures in T1D was 52.14 events per 100,000 person years and 73.21 per 100,000 person years in T2D. T1D was associated with an increased risk of ST/FS (HR 2.07 (95% CI 1.68-2.56)), whereas T2D was not (HR 0.99 (95% CI 0.94-1.10)). Previous ST/FS fractures were associated with an increased risk of subsequent ST/FS fractures (HR 6.95 (95% CI 6.00-8.05)) and the use of bisphosphonates with an increased risk of ST/FS fractures (HR 1.72 (95% CI 1.54-1.91)).

CONCLUSION

Patients with T1D have a higher risk of ST/FS fractures compared with sex- and age-matched controls. Since a proportion of ST/FS fractures are classified as AFFs, this could point towards the fact that AFFs also are increased in patients with T1D, but not T2D.

Age at hip fracture and life expectancy in Denmark - Secular trends over two decades

BACKGROUND

Recent improvements in the health of the oldest old coexist with a decline in hip fracture rates, in particular in women. We speculated that increased longevity with decreasing hip fracture rates would result in a delay in hip fracture. We conducted an analysis of time trends in the age at hip fracture, by type and gender, for the past two decades using national data.

STUDY POPULATION AND METHODS

We used data from the Danish Hospital Discharge Register (1996-2017) to analyse the age distribution of femoral neck (FN) and pertrochanteric fractures (PT), allowing only the first fracture at each of these two sites to contribute to the analysis in each calendar year. Demographics for the background population at risk including life expectancy tabulations, were also obtained.

RESULTS

The average age at FN fracture in women increased slowly but significantly by 0.035years - or 12.8 days - per calendar year [0.035, 95% CI (0.016; 0.054), p<0.001], resulting in an increase from 79.6 to 80.4 years. There were no significant changes in the age at FN fracture in men or the age at PT fracture in women and men. Further, increases in life expectancy were considerably faster than any change observed in the age at hip fracture. In 1996, the average age at FN or PT fracture exceeded the average life expectancy in both men and women whereas the opposite was the case from 2009 and onwards in men and 2015 and onwards in women.

CONCLUSION

This study demonstrates a significant change in the demographics of hip fractures in Denmark over the past two decades. We observed a significant increase in the age at FN fracture in women but not in men, with no significant increase in the age at IT fracture and PT fracture. This developed much more slowly, however, than the increase in life expectancy in both sexes observed over the same period of time. Taken together, these changes resulted in a large decrease in the female to male incidence rate ratio from 2.6 and 2.5 (FN and PT, respectively) to 1.9 and 1.7.Additional effort is required to prevent hip fractures to ensure that the increasing life expectancy is matched by a similar increase in hip-fracture free life expectancy.

Hypoglycaemia and type 1 diabetes are associated with an increased risk of fractures

People with diabetes have an increased risk of fractures, and in this study, the effect of hypoglycaemia and insulin on this risk was investigated. Type 1 diabetes and hypoglycaemia did increase the fracture risk, and prevention of hypoglycaemia is thus an important focus area in the prevention of fractures.

INTRODUCTION

Studies have shown that type 1 diabetes (T1D) and type 2 diabetes (T2D) are associated with increased risk of fractures. Especially, subjects with T1D have an increased risk of fractures. The purpose of this study was to investigate the association of T1D, hypoglycaemia and insulin on fracture risk.

METHODS

A cohort study with T1D subjects (n = 19,896) and T2D subjects (n = 312,188) matched with subjects from the general populated (n = 996,252) and a nested case-control study with T1D subjects with fracture (n = 895) as cases and T1D subjects without (n = 2685) as controls were conducted based on subjects from the Danish National Patient Registry (DNPR).

RESULTS

T1D (HR = 2.47, 95% CI 2.37 to 2.59), age (HR = 1.05, 95% CI 1.05 to 1.05), previous fracture (HR = 1.95, 95% CI 1.92 to 1.99) and being female (HR = 2.06, 95% CI 2.04 to 2.09) increased the risk of fractures. Also, T2D (HR = 1.14, 95% CI 1.11 to 1.18) increased the risk of proximal upper arm and shoulder fractures. T1D (HR = 2.41, 95% CI 2.20 to 2.65) increased the risk of hip and femoral region fractures. Hypoglycaemia (OR = 1.58, 95% CI 1.27 to 1.97) increased the risk of fractures, whereas insulin use did not change the risk.

CONCLUSIONS

Hypoglycaemic episodes are associated with increased fracture risk, and the frequency of hypoglycaemic episodes leading to hospital admission was above 16% for T1D subjects. Prevention of hypoglycaemia is thus an important focus area in the prevention of fractures.

Prediction of exacerbation onset in chronic obstructive pulmonary disease patients

The objective of this study was to develop an algorithm for prediction of exacerbation onset in Chronic Obstructive Pulmonary Disease (COPD) patients based on continuous self-monitoring of physiological parameters from telehome-care monitoring. 151 physiological parameters of COPD patients were monitored on a daily/weekly basis for up to 2 years. Data were segmented in 30-day periods leading up to an exacerbation (exacerbation episode) and starting from a 14-day recovery period post-exacerbation (control episode) and tested in 6 intervals to predict exacerbation onset using k-nearest neighbour (k = 1, 3, 5). A classifier with sensitivity of 73%, specificity of 74%, positive predictive value of 69%, negative predictive value of 78% and an accuracy of 74% was achieved using data intervals consisting of 5 days. Intelligent processing of physiological recordings have potential for predicting exacerbation onset.

A systematic study of the isothermal crystallization of the mono-alcohol n-butanol monitored by dielectric spectroscopy

Isothermal crystallization of the mono-hydroxyl alcohol n-butanol was studied with dielectric spectroscopy in real time. The crystallization was carried out using two different sample cells at 15 temperatures between 120 K and 134 K. Crystallization is characterized by a decrease of the dielectric intensity. In addition, a shift in relaxation times to shorter times was observed during the crystallization process for all studied temperatures. The two different sample environments induced quite different crystallization behaviors, consistent and reproducible over all studied temperatures. An explanation for the difference was proposed on the background of an Avrami analysis and a Maxwell-Wagner analysis. Both types of analysis suggest that the morphology of the crystal growth changes from a higher dimension to a lower at a point during the crystallization. More generally, we conclude that a microscopic interpretation of crystallization measurements requires multiple probes, sample cells, and protocols.

The dynamics of genetic control in the cell: the good and bad of being late

The expression of genes in the cell is controlled by a complex interaction network involving proteins, RNA and DNA. The molecular events associated with the nodes of such a network take place on a variety of time scales, and thus cannot be regarded as instantaneous. In many cases, the cell is robust with respect to the delay in gene expression control, behaving as if it were instantaneous. However, there are specific cases in which delay gives rise to temporal oscillations. This is the case, for example, of the expression of tumour-suppressor protein p53, of protein Hes1, involved in the differentiation of stem cells, of NFkB and Wnt, in which case delay arises implicitly from the structure of the associated network. By means of delay rate equations, we study the kinetics of small regulatory networks, emphasizing the role of delay in an evolutionary context. These models suggest that oscillations are a typical outcome of the dynamics of regulatory networks, and evolution has to work to avoid them when not required (and not vice versa).

A diet management information and communication system to help chronic kidney patients cope with diet restrictions

Hyperphosphatemia, hyperkalemia, and fluid overload are frequently observed and pose major physiological concerns in chronic kidney patients. The problems are closely related to inadequate diet and phosphate binder intake, which are considerable challenges for many patients. The objective of this study was to develop and test an educational decision support system to help kidney patients cope with diet restrictions and phosphate binder dosage. A prototype was designed including three main functions: 1) information and education, 2) food analyser database and diet registration, and 3) model-based decision support to phosphate binder dosage. The functions and the usability of the prototype were evaluated through user testing and qualitative interviews including five kidney patients. The decision support function was modified and tested using experimental data. In conclusion, the system was evaluated to be a relevant, and potentially beneficial tool to cope with kidney diet restrictions. Further data are necessary to validate the correct phosphate binder dosage and assess the ability of the system to decrease the incidence of fluid and electrolyte disorders in kidney patients.

Moving prediction of exacerbation in chronic obstructive pulmonary disease for patients in telecare

We investigated whether physiological data can be used for predicting chronic obstructive pulmonary disease (COPD) exacerbations. Home measurements from 57 patients were analysed, during which 10 exacerbations occurred in nine patients. A total of 273 different features were evaluated for their discrimination abilities between periods with and without exacerbations. The analysis showed that if a sensitivity level of 70% is considered to be acceptable, then the specificity was 95% and the AUC was 0.73, i.e. it is possible to discriminate between periods of exacerbation and periods without. A system capable of predicting risk could provide support to COPD patients in their tele-rehabilitation.

Emergence and decline of scientific paradigms

Scientific paradigms have a tendency to rise fast and decline slowly. This asymmetry reflects the difficulty in developing a truly original idea, compared to the ease at which a concept can be eroded by numerous modifications. Here we formulate a model for the emergence and spread of ideas which deals with this asymmetry by constraining the ability of agents to return to already abandoned concepts. The model exhibits a fairly regular pattern of global paradigm shifts, where older paradigms are eroded and subsequently replaced by new ones. The model sets the theme for a new class of pattern formation models, where local dynamics breaks the detailed balance in a way that prevents old states from defending themselves against new nucleating or invading states. The model allows for frozen events in terms of the coexistence of multiple metastable states.

Frustrated bistability as a means to engineer oscillations in biological systems

Oscillations play an important physiological role in a variety of biological systems. For example, respiration and carbohydrate synthesis are coupled to the circadian clock in cyanobacteria (Ishiura et al 1998 Science 281 1519) and ultradian oscillations with time periods of a few hours have been observed in immune response (NF-kappaB, Hoffmann et al 2002 Science 298 1241, Neson et al 2004 Science 306 704), apoptosis (p53, Lahav et al 2004 Nat. Genet. 36 53), development (Hes, Hirata et al 2002 Science 298 840) and growth hormone secretion (Plotsky and Vale 1985 Science 230 461, Zeitler et al 1991 Proc. Natl. Acad. Sci. USA 88 8920). Here we discuss how any bistable system can be 'frustrated' to produce oscillations of a desired nature--we use the term frustration, in analogy to frustrated spins in antiferromagnets, to refer to the addition of a negative feedback loop that destabilizes the bistable system. We show that the molecular implementation can use a wide variety of methods ranging from translation regulation, using small non-coding RNAs, to targeted protein modification to transcriptional regulation. We also introduce a simple graphical method for determining whether a particular implementation will produce oscillations. The shape of the resulting oscillations can be readily tuned to produce spiky and asymmetric oscillations--quite different from the shapes produced by synthetic oscillators (Elowitz and Leibler 2000 Nature 403 335, Fung et al 2005 Nature 435 118). The time period and amplitude can also be manipulated and these oscillators are easy to reset or switch on and off using a tunable external input. The mechanism of frustrated bistability could thus prove to be an easily implementable way to synthesize flexible, designable oscillators.

Oscillations and temporal signalling in cells

The development of new techniques to quantitatively measure gene expression in cells has shed light on a number of systems that display oscillations in protein concentration. Here we review the different mechanisms which can produce oscillations in gene expression or protein concentration using a framework of simple mathematical models. We focus on three eukaryotic genetic regulatory networks which show 'ultradian' oscillations, with a time period of the order of hours, and involve, respectively, proteins important for development (Hes1), apoptosis (p53) and immune response (NF-kappaB). We argue that underlying all three is a common design consisting of a negative feedback loop with time delay which is responsible for the oscillatory behaviour.

Thermodynamic formalism of the harmonic measure of diffusion limited aggregates: phase transition

We study the nature of the phase transition in the multifractal formalism of the harmonic measure of diffusion limited aggregates. Contrary to previous work that relied on random walk simulations or ad hoc models to estimate the low probability events of deep fjord penetration, we employ the method of iterated conformal maps to obtain an accurate computation of the probability of the rarest events. We resolve probabilities as small as 10(-35). We show that the generalized dimensions D(q) are infinite for q<q*, where q* = -0.18+/-0.04. In the language of f(alpha) this means that alpha(max) is finite. We present a converged f(alpha) curve.

Release of CFC-11 from disposal of polyurethane foam waste

The halocarbon CFC-11 has extensively been used as a blowing agent for polyurethane (PUR) insulation foams in home appliances and for residential and industrial construction. Release of CFCs is an important factor in the depletion of the ozone layer. For CFC-11 the future atmospheric concentrations will mainly depend on the continued release from PUR foams. Little is known about rates and time frames of the CFC release from foams especially after treatment and disposal of foam containing waste products. The CFC release is mainly controlled by slow diffusion out through the PUR. From the literature and by reevaluation of an old reported experiment, diffusion coefficients in the range of 0.05-1.7 x 10(-14) m2 s-1 were found reflecting differences in foam properties and experimental designs. Laboratory experiments studying the distribution of CFC in the foam and the short-term releases after shredding showed that about 40% of the CFC is solubilized in the PUR phase, and that up to 10% of the total content will be released within a few weeks if the foam is shredded down to 2-cm sized pieces. For smaller pieces the quick release will be larger. Fifty percent of residual CFC content will be released within 9-300 years from 2-cm pieces based on the range in diffusion coefficients reported. For larger pieces the initial release is insignificant, and the release time frames are much longer than for the shredded foam.

Hydrogen bonds in polymer folding

We studied the thermodynamics of a homopolymeric chain with both van der Waals and directed hydrogen bond interaction. The effect of hydrogen bonds is to reduce dramatically the entropy of low-lying states and to give rise to long-range order and to conformations displaying secondary structures. For compact polymers a transition is found between helix-rich states and low-entropy sheet-dominated states. The consequences of this transition for protein folding and, in particular, for the problem of prions are discussed.

Pathways in two-state protein folding

Thermodynamic measurements of proteins indicate that the folding to the native state takes place either through stable intermediates or through a two-state process without intermediates. The rather short folding times of proteins indicate that folding is guided through some sequence of contact bindings. We discuss the possibility of reconciling a two-state folding event with a sequential folding process in a schematic model of protein folding. We propose a new dynamical transition temperature that is lower than the temperature at which proteins in equilibrium unfold. This is in qualitative agreement with observations of in vivo protein folding activity quantified by chaperone concentration in Escherichia coli. Finally, we discuss our framework in connection with the unfolding of proteins at low temperatures.

Fixed points, stability, and intermittency in a shell model for advection of passive scalars

We investigate the fixed points of a shell model for the turbulent advection of passive scalars introduced in Jensen, Paladin, and Vulpiani [Phys. Rev. A 45, 7214 (1992)]. The passive scalar field is driven by the velocity field of the popular Gledzer-Ohkitani-Yamada (GOY) shell model. The scaling behavior of the static solutions is found to differ significantly from Obukhov-Corrsin scaling straight theta(n) approximately k(-1/3)(n), which is only recovered in the limit where the diffusivity vanishes, D-->0. From the eigenvalue spectrum we show that any perturbation in the scalar will always damp out, i.e., the eigenvalues of the scalar are negative and are decoupled from the eigenvalues of the velocity. We estimate Lyapunov exponents and the intermittency parameters using a definition proposed by Benzi, Paladin, Parisi, and Vulpiani [J. Phys. A 18, 2157 (1985)]. The full model is found to be as chaotic as the GOY model, measured by the maximal Lyapunov exponent, but is more intermittent.

Augmentative and alternative communication in logopedics

Like logopedics, augmentative and alternative communication (AAC) has a short history and a long past. In the 1950s and 60s the field of AAC emerged as a response to the need of individuals who, despite years of 'traditional speech therapy', had not developed adequate oral communication skills, and for whom compensatory rather than remedial approaches were thus deemed advisable. Various trends like the shift from form to function in language development research, dissemination of sign language, use of non-speech graphic symbols, advances in computer technology, and international collaboration have all contributed to AAC's present-day status as a multidisciplinary enterprise involving speech-language therapists and an array of other professions. Clinical experience, for lack of comprehensive empirical studies, seems to indicate that AAC is warranted for congenital as well as acquired communication disorders.

Production of a highly immunogenic subunit ISCOM vaccine against Bovine Viral Diarrhea Virus

Bovine Viral Diarrhea Virus (BVDV) is a major pathogen of cattle in most countries. The main reservoir of virus in herds are BVDV persistently infected animals, which arise as a result of infection of the bovine fetus early in gestation. The spread of virus to the unborn fetus may be prevented by vaccination of the dam. We describe in this report the production and initial testing of an inactivated subunit vaccine against BVDV. The vaccine is based on production of antigen in primary bovine cell cultures, extraction of antigens from infected cells with detergent, chromatographic purification, concentration, and insertion of antigens into immune stimulating complexes (ISCOMs). Vaccines based on two different Danish strains of BVDV were injected into calves and the antisera produced were tested for neutralising activity against a panel of Danish BVDV strains. The two vaccines induced different neutralisation responses, which seem to partly complement each other. The implication of these observations for successful vaccination against BVDV is discussed.

Detection of antibodies against porcine parvovirus nonstructural protein NS1 may distinguish between vaccinated and infected pigs

The humoral antibody response against the nonstructural protein NS1 and the structural protein VP2 of porcine parvovirus (PPV) was evaluated by immuno-peroxidase test (IPT) and enzyme linked immuno sorbent assay (ELISA) using recombinant PPV antigens. The coding sequence for NS1 and VP2 was inserted into the baculovirus. Autographa californica nuclear polyhedrosis virus (AcNPV) genome resulting in two recombinant baculoviruses AcNPV-NS1 and AcNPV-VP2, respectively. Sf9 cells (Spodoptora frugidiperda) inoculated with AcNPV-NS1 producing recombinant nonstructural protein (rNS1) and AcNPV-VP2 producing recombinant virion protein (rVP2) were used in IPT and ELISA to analyse serum antibodies. Pigs vaccinated with an inactivated whole virus vaccine and experimentally infected pigs were studied. Significant titers against rVP2 were obtained in both vaccinated and infected pigs. Specific antibodies against rNS1 could only be detected in infected pigs and NS1 may in this way allow the specific detection of infected animals. Analysis of serum samples collected up to 18 days post infection (p.i.) from four pigs experimentally infected with PPV showed that antibodies against rNS1 and rVP2 could in all cases be detected on day 9 p.i. Two individual pigs were inoculated twice with PPV and the antibody response was followed 89 days after second inoculation. Serum antibodies against both rVP2 and rNS1 could be detected for this period of time.

Evolution as a self-organized critical phenomenon

We present a simple mathematical model of biological macroevolution. The model describes an ecology of adapting, interacting species. The environment of any given species is affected by other evolving species; hence, it is not constant in time. The ecology as a whole evolves to a "self-organized critical" state where periods of stasis alternate with avalanches of causally connected evolutionary changes. This characteristic behavior of natural history, known as "punctuated equilibrium," thus finds a theoretical explanation as a self-organized critical phenomenon. The evolutionary behavior of single species is intermittent. Also, large bursts of apparently simultaneous evolutionary activity require no external cause. Extinctions of all sizes, including mass extinctions, may be a simple consequence of ecosystem dynamics. Our results are compared with data from the fossil record.

Synthesis and characterization of Desulfovibrio gigas rubredoxin and rubredoxin fragments

The 52-residue Desulfovibrio gigas rubredoxin peptide chain has been synthesized and a procedure for chain folding around iron(II) developed. The folded, stable synthetic rubredoxin can be subjected to purification, and reversibly oxidized and reduced. Ultraviolet/visible absorption and CD spectra of both forms show all the same features as native D. gigas rubredoxin, and the symmetric and asymmetric Fe-S stretching bands in the resonance Raman spectrum can be identified. In addition, the matrix-assisted laser desorption mass spectrum of a peptide sample exposed to trace amounts of iron is dominated by a peak at 5735Da very close to the value for the calculated molecular mass. Details in the ultraviolet/visible bandshape and mass spectrum, however, indicate remaining impurities. In comparison, a previously synthesized 25-residue rubredoxin fragment with the non-conserved positions 13-35 and 51-52 omitted and Val5-Glu50 anchored via glycine folds gives the correct molecular mass and ultraviolet/visible spectrum, but is much more labile than the 52-residue protein. This shows that non-conserved residues are crucial in protein folding and that chemical metalloprotein synthesis offers alternative prospects to microbiological protein engineering.