Acute loading has minor influence on human articular cartilage gene expression and glycosaminoglycan composition in late-stage knee osteoarthritis: a randomised controlled trial

OBJECTIVE

Osteoarthritis (OA) remains clinically challenging. Regular physical exercise improves symptoms though it is unclear whether exercise influences cartilage at the molecular level. Thus, we aimed to determine the effect of acute loading on gene expression and glycosaminoglycan (GAG) content in human OA cartilage.

DESIGN

Patients with primary knee OA participated in this single-blind randomised controlled trial initiated 3.5 h prior to scheduled joint replacement surgery with or without loading by performing one bout of resistance exercise (one-legged leg press). Cartilage from the medial tibia condyle was sampled centrally, under the meniscus, and from peripheral osteophytes. Samples were analysed for gene expression by real-time reverse transcriptase polymerase chain reaction, and hyaluronidase-extracted matrix was analysed for GAG composition by immuno- and dimethyl-methylene blue assays.

RESULTS

Of 32 patients randomised, 31 completed the intervention: mean age 69 ± 7.5 years (SD), 58% female, BMI 29.4 ± 4.4 kg/m². Exercise increased chondroitin sulphate extractability [95% CI: 1.01 to 2.46; P = 0.0486] but cartilage relevant gene expression was unchanged. Regionally, the submeniscal area showed higher MMP-3, MMP-13, IGF-1Ea, and CTGF, together with lower lubricin and COMP expression compared to the central condylar region. Further, osteophyte expression of MMP-1, MMP-13, IGF-1Ea, and TGF-β3 was higher than articular cartilage and lower for aggrecan, COMP, and FGF-2. Hyaluronidase-extracted matrix from central condylar cartilage contained more GAGs but less chondroitin sulphate compared to submeniscal cartilage.

CONCLUSION

Acute exercise had minor influence on cartilage GAG dynamics, indicating that osteoarthritic cartilage is not significantly affected by acute exercise. However, the regional differences suggest a chronic mechanical influence on human cartilage.

CLINICALTRIALS

GOV REGISTRATION NUMBER

NCT03410745.

Trajectory of cognitive impairments over 1 year after COVID-19 hospitalisation: Pattern, severity, and functional implications

The ongoing Coronavirus Disease (COVID-19) pandemic has so far affected more than 500 million people. Lingering fatigue and cognitive difficulties are key concerns because they impede productivity and quality of life. However, the prevalence and duration of neurocognitive sequelae and association with functional outcomes after COVID-19 are unclear. This longitudinal study explored the frequency, severity and pattern of cognitive impairment and functional implications 1 year after hospitalisation with COVID-19 and its trajectory from 3 months after hospitalisation. Patients who had been hospitalised with COVID-19 from our previously published 3-months study at the Copenhagen University Hospital were re-invited for a 1-year follow-up assessment of cognitive function, functioning and depression symptoms. Twenty-five of the 29 previously assessed patients (86%) were re-assessed after 1 year (11±2 months). Clinically significant cognitive impairments were identified in 48-56 % of patients depending on the cut-off, with verbal learning and executive function being most severely affected. This was comparable to the frequency of impairments observed after 3 months. Objectively measured cognitive impairments scaled with subjective cognitive difficulties, reduced work capacity and poorer quality of life. Further, cognitive impairments after 3 months were associated with the severity of subsequent depressive symptoms after 1 year. In conclusion, the stable cognitive impairments in approximately half of patients hospitalized with COVID-19 and negative implications for work functioning, quality of life and mood symptoms underline the importance of screening for and addressing cognitive sequelae after severe COVID-19.

Hemoglobin A1c-levels and subsequent risk of depression in individuals with and without diabetes

BACKGROUND

It has been suggested that long-term glycemic load as reflected in plasma levels of Glycosylated Hemoglobin, Type A1C (HbA1c) is associated with higher risk of depression, however results have been conflicting. We examined the potential association between HbA1c and risk of depression in a large population-based cohort without baseline diabetes (the Glostrup cohort) defined by either self-reported diabetes, registry diagnosis of diabetes or use of antidiabetic medication at baseline and in a national diabetes cohort (the Danish Adult Diabetes Database).

METHODS

A total of 16,124 middle-aged individuals from the Glostrup cohort and 93,544 patients registered in the Danish Adult Diabetes Database were followed from the first registered HbA1c measurement (1999-2014) for subsequent diagnosis of depression or use of antidepressant medication in nation-wide Danish registers. The association was analyzed using a Cox proportional hazards regression model with HbA1c on both a continuous scale using restricted cubic splines and categorized based on the groups found in the spline model. We adjusted for relevant sociodemographic and clinical variables including previous depression and tested for interaction of both gender, insulin use and diabetes type.

RESULTS

During follow-up, 2694 (17%) in the Glostrup cohort and 29,234 (31%) in the diabetes cohort developed depression. In the Glostrup cohort, we found an indication of a positive linear association between HbA1c and depression in women, while no clear association was found in men. In patients with diabetes, we found a U-shaped association between HbA1c and depression in both men and women with the lowest risk estimates for HbA1c levels of 58 mmol/mol (7.5%) in men and of 60 mmol/mol (7.6%) in women. When HbA1c was categorized, men with the highest HbA1c-levels had significantly elevated risk of depression (HR_HbA1c>9.4 1.16 (95%CI 1.10-1.23)) after multifactorial adjustment compared to the reference group with HbA1c of 42.1-56.2 mmol/mol (6.0-7.3%). Women in the lowest and highest category of HbA1c had significantly higher risk of depression HR_HbA1c<6.0 1.15 (95% CI 1.09-1.22) and HR_HbA1c>9.3 1.10 (95% CI 1.04-1.16), respectively, compared to the reference group with HbA1c 42.1-55.0 mmol/mol (7.2-9.3%). There was a significant interaction with gender, but no interaction for insulin use or diabetes type.

CONCLUSIONS

In a population without baseline diabetes, higher HbA1c levels seemed associated with higher depression risk in women, whereas a U-shaped association was found in patients with known diabetes.

Cognitive impairments four months after COVID-19 hospital discharge: Pattern, severity and association with illness variables

The ongoing Coronavirus Disease 2019 (COVID-19) pandemic has affected more than 100 million people and clinics are being established for diagnosing and treating lingering symptoms, so called long-COVID. A key concern are neurological and long-term cognitive complications. At the same time, the prevalence and nature of the cognitive sequalae of COVID-19 are unclear. The present study aimed to investigate the frequency, pattern and severity of cognitive impairments 3-4 months after COVID-19 hospital discharge, their relation to subjective cognitive complaints, quality of life and illness variables. We recruited patients at their follow-up visit at the respiratory outpatient clinic, Copenhagen University Hospital, Bispebjerg, approximately four months after hospitalisation with COVID-19. Patients underwent pulmonary, functional and cognitive assessments. Twenty-nine patients were included. The percentage of patients with clinically significant cognitive impairment ranged from 59% to 65% depending on the applied cut-off for clinical relevance of cognitive impairment, with verbal learning and executive functions being most affected. Objective cognitive impairment scaled with subjective cognitive complaints, lower work function and poorer quality of life. Cognitive impairments were associated with d-dimer levels during acute illness and residual pulmonary dysfunction. In conclusion, these findings provide new evidence for frequent cognitive sequelae of COVID-19 and indicate an association with the severity of the lung affection and potentially restricted cerebral oxygen delivery. Further, the associations with quality of life and functioning call for systematic cognitive screening of patients after recovery from severe COVID-19 illness and implementation of targeted treatments for patients with persistent cognitive impairments.

Characteristics influencing expected cognitive performance during hypoglycaemia in type 2 diabetes

BACKGROUND

Acute hypoglycaemia is associated with cognitive impairment in patients with type 2 diabetes. However, there is limited understanding of the relationship between patients' expected cognitive difficulties and their objectively-measured deficits during non-severe hypoglycaemia.

OBJECTIVE

This report investigates demographic and clinical factors associated with the discrepancy between expected (i.e., self-evaluated) and measurable (i.e., neuropsychological) cognitive functions in patients with type 2 diabetes during acute non-severe hypoglycaemia.

METHODS

We performed an analysis of factors associated with the relationship between expected and measurable cognitive performance for data collected from a cohort of patients with type 2 diabetes (N = 25). Patients attended two experimental visits during which we performed hyper-insulinaemic glucose clamping; (i) non-severe hypoglycaemic clamp (plasma glucose (PG): 3.1 ± 0.3 mmol/L) and (ii) normoglycaemic clamp (PG: 5.8 ± 0.3 mmol/L), as part of a double-blinded cross-over study. During hypoglycaemia, patients' expected cognitive performance was assessed with a visual analogue scale after which objective cognitive functions were assessed with a neuropsychological test battery. We computed a global 'cognitive discrepancy' composite variable with score values on a scale between -10 and +10 using a novel statistical formula that creates a discrepancy score between subjective and objective cognition. Positive values reflect more expected than objectively-measured difficulties, while negative values reflect disproportionately more objectively-measured than expected cognitive difficulties. We used paired samples t-tests to compare degree of cognitive discrepancy between conditions of hypo- and normoglycaemia, while multiple regression analysis was performed to identify factors associated with the degree and direction of the cognitive discrepancy. The significance level for the analyses was p ≤ 0.05 (two-tailed).

RESULTS

Patients generally underestimated their cognitive abilities (M = 1.6, SD = 3.3) during hypoglycaemia compared to normoglycaemia (M = -1.0, SD = 3.5) (p = 0.2), t(23) = 2.9, p < 0.01. Underestimation of cognitive capacity during hypoglycaemia was more pronounced for patients with younger age (β = 0.5, p = 0.02), higher verbal IQ (β = 0.5, p = 0.03), and more hypoglycaemia-related shakiness (β = 0.4, p = 0.03).

LIMITATIONS

The modest sample size limits the generalizability of the findings.

CONCLUSIONS

Patients with type 2 diabetes underestimated their cognitive abilities during non-severe hypoglycaemic states, especially those with younger age, higher IQ, and more hypoglycaemia-related shakiness. These patients may thus have excessive preoccupations with their cognitive difficulties in relation to cognitively challenging daily life situations.

Early-onset type 2 diabetes: Age gradient in clinical and behavioural risk factors in 5115 persons with newly diagnosed type 2 diabetes-Results from the DD2 study

AIM

To examine the association between early onset of type 2 diabetes mellitus (DM) and clinical and behavioural risk factors for later complications of diabetes.

METHODS

We conducted a cross-sectional study of 5115 persons with incident type 2 DM enrolled during 2010-2015 in the Danish Centre for Strategic Research in Type 2 Diabetes-cohort. We compared risk factors at time of diagnosis among those diagnosed at ≤45 years (early onset) with diagnosis age 46 to 55, 56 to 65 (average onset = reference), 66 to 75, and >75 years (late onset). Prevalence ratios (PRs) were computed by using Poisson regression.

RESULTS

Poor glucose control, ie, HbA1c ≥ 75 mmol/mol (≥9.0%) in the early-, average-, and late-onset groups was observed in 12%, 7%, and 1%, respectively (PR 1.70 [95% confidence intervals (CI) 1.27, 2.28] and PR 0.17 [95% CI 0.06, 0.45]). A similar age gradient was observed for severe obesity (body mass index > 40 kg/m² : 19% vs. 8% vs. 2%; PR 2.41 [95% CI 1.83, 3.18] and 0.21 (95% CI 0.08, 0.57]), dyslipidemia (90% vs. 79% vs. 68%; PR 1.14 [95% CI 1.10, 1.19] and 0.86 [95% CI 0.79, 0.93]), and low-grade inflammation (C-reactive protein > 3.0 mg/L: 53% vs. 38% vs. 26%; PR 1.41 [95% CI 1.12, 1.78] and 0.68 [95% CI 0.42, 1.11]). Daily smoking was more frequent and meeting physical activity recommendations less likely in persons with early-onset type 2 DM.

CONCLUSIONS

We found a clear age gradient, with increasing prevalence of clinical and behavioural risk factors the younger the onset age of type 2 DM. Younger persons with early-onset type 2 DM need clinical awareness and support.

Obesity and age-related alterations in the gene expression of zinc-transporter proteins in the human brain

The incidence of Alzheimer's disease (AD) is increasing. Major risk factors for AD are advancing age and diabetes. Lately, obesity has been associated with an increased risk of dementia. Obese and diabetic individuals are prone to decreased circulating levels of zinc, reducing the amount of zinc available for crucial intracellular processes. In the brain, zinc co-localizes with glutamate in synaptic vesicles, and modulates NMDA receptor activity. Intracellular zinc is involved in apoptosis and fluctuations in cytoplasmic Zn(2+) affect modulation of intracellular signaling. The ZNT and ZIP proteins participate in intracellular zinc homeostasis. Altered expression of zinc-regulatory proteins has been described in AD patients. Using microarray data from human frontal cortex (BrainCloud), this study investigates expression of the SCLA30A (ZNT) and SCLA39A (ZIP) families of genes in a Caucasian and African-American sample of 145 neurologically and psychiatrically normal individuals. Expression of ZNT3 and ZNT4 were significantly reduced with increasing age, whereas expression of ZIP1, ZIP9 and ZIP13 were significantly increased. Increasing body mass index (BMI) correlated with a significant reduction in ZNT1 expression similar to what is seen in the early stages of AD. Increasing BMI also correlated with reduced expression of ZNT6. In conclusion, we found that the expression of genes that regulate intracellular zinc homeostasis in the human frontal cortex is altered with increasing age and affected by increasing BMI. With the increasing rates of obesity throughout the world, these findings warrant continuous scrutiny of the long-term consequences of obesity on brain function and the development of neurodegenerative diseases.

GLP-1 and Amylin in the Treatment of Obesity

For decades, extensive research has aimed to clarify the role of pancreas and gut-derived peptide hormones in the regulation of glucose homeostasis and feeding behavior. Among these are the beta-cell hormone amylin and the intestinal L cell hormone glucagon-like peptide-1 (GLP-1). They exhibit distinct and yet several similar physiological actions including suppression of food intake, postprandial glucagon secretion, and gastric emptying-altogether lowering plasma glucose and body weight. These actions have been clinically exploited by the development of amylin and GLP-1 hormone analogs now used for treatment of diabetes and obesity. This review will outline the physiology and pharmacological potential of amylin and GLP-1, respectively, and focus on innovative peptide drug development leading to drugs acting on two or more distinct receptors, such as an amylin and GLP-1 peptide hybrid, potentially producing a more effective treatment strategy to combat the rapidly increasing global obesity.

Prescribing practices and clinical predictors of glucose-lowering therapy within the first year in people with newly diagnosed Type 2 diabetes

AIM

To examine prescribing practices and predictors of glucose-lowering therapy within the first year following diagnosis of Type 2 diabetes mellitus in a clinical care setting.

METHODS

We followed people enrolled in the Danish Centre for Strategic Research in Type 2 Diabetes (DD2) cohort from outpatient hospital clinics and general practices throughout Denmark in 2010-2013. We used Poisson regression to compute age- and gender-adjusted risk ratios (RRs).

RESULTS

Among 1158 new Type 2 diabetes mellitus patients, 302 (26%) did not receive glucose-lowering therapy within the first year, 723 (62%) received monotherapy [685 (95%) with metformin], and 133 (12%) received more than one drug. Predictors of receiving any vs. no therapy and combination vs. monotherapy were: age < 40 years [RR: 1.29 (95% CI: 1.16-1.44) and 3.60 (95% CI: 2.36-5.50)]; high Charlson Comorbidity Index [RRs: 1.20 (95% CI: 1.05-1.38) and 2.08 (95% CI: 1.16-3.72)]; central obesity [RRs: 1.23 (95% CI: 1.04-1.44) and 1.93 (95% CI: 0.76-4.94)]; fasting blood glucose of ≥ 7.5 mmol/l [RRs: 1.25 (95% CI: 1.10-1.42) and 1.94 (95% CI: 1.02-3.71)]; and HbA1c ≥ 59 mmol/mol (≥ 7.5%) [RR: 1.26 (95% CI: 1.20-1.32) and 2.86 (95% CI: 1.97-4.14)]. Weight gain ≥ 30 kg since age 20, lack of physical exercise and C-peptide of < 300 pmol/l also predicted therapy.

CONCLUSIONS

Comorbidity, young age, central obesity and poor baseline glycaemic control are important predictors of therapy one year after Type 2 diabetes mellitus debut.

Rosiglitazone use and post-discontinuation glycaemic control in two European countries, 2000-2010

OBJECTIVES

To evaluate the impact of risk minimisation policies on the use of rosiglitazone-containing products and on glycaemic control among patients in Denmark and the UK.

DESIGN, SETTING AND PARTICIPANTS

We used population-based data from the Aarhus University Prescription Database (AUPD) in northern Denmark and from the General Practice Research Database (GPRD) in the UK.

MAIN OUTCOME MEASURES

We examined the use of rosiglitazone during its entire period of availability on the European market (2000-2010) and evaluated changes in the glycated haemoglobin (HbA1c) and fasting plasma glucose (FPG) levels among patients discontinuing this drug.

RESULTS

During 2000-2010, 2321 patients with records in AUPD used rosiglitazone in northern Denmark and 25 428 patients with records in GPRD used it in the UK. The proportion of rosiglitazone users among all users of oral hypoglycaemic agents peaked at 4% in AUPD and at 15% in GPRD in May 2007, the month of publication of a meta-analysis showing increased cardiovascular morbidity associated with rosiglitazone use. 12 months after discontinuation of rosiglitazone-containing products, the mean change in HbA1c was -0.16% (95% CI -3.4% to 3.1%) in northern Denmark and -0.17% (95% CI -0.21% to 0.13%) in the UK. The corresponding mean changes in FPG were 0.01 mmol/L (95% CI -7.3 to 7.3 mmol/L) and 0.03 mmol/L (95% CI -0.22 to 0.28 mmol/L).

CONCLUSIONS

Publication of evidence concerning the potential cardiovascular risks of rosiglitazone was associated with an irreversible decline in the use of rosiglitazone-containing products in Denmark and the UK. The mean changes in HbA1c and FPG after drug discontinuation were slight.

The impact of calcineurin inhibitors on insulin sensitivity and insulin secretion: a randomized crossover trial in uraemic patients

AIMS

The calcineurin inhibitors cyclosporine and tacrolimus are implicated in post-transplant complications such as new-onset diabetes after transplantation. The relative contribution of each calcineurin inhibitor to new-onset diabetes after transplantation remains unclear. We sought to compare the impact of cyclosporine and tacrolimus on glucose metabolism in humans.

METHODS

Eight haemodialysis patients received 8-10 days of oral treatment followed by 5-h infusions with cyclosporine, tacrolimus and saline in a randomized, investigator-blind, crossover study. Glucose metabolism and β-cell function was investigated through: a hyperinsulinaemic-euglycaemic clamp, an intravenous glucose tolerance test and insulin concentration time series.

RESULTS

Cyclosporine and tacrolimus decreased insulin sensitivity by 22% (P = 0.02) and 13% (P = 0.048), respectively. The acute insulin response and pulsatile insulin secretion were not significantly affected by the drugs.

CONCLUSION

In conclusion, 8-10 days of treatment with cyclosporine and tacrolimus impairs insulin sensitivity to a similar degree in haemodialysis patients, while acute insulin responses and pulsatile insulin secretion remain unaffected.

Exenatide alters myocardial glucose transport and uptake depending on insulin resistance and increases myocardial blood flow in patients with type 2 diabetes

CONTEXT

Glucagon-like peptide-1 (GLP-1) and GLP-1 receptor agonists provide beneficial cardiovascular effects by protecting against ischemia and reperfusion injury. Type 2 diabetes mellitus patients have reduced glycolysis in the heart.

OBJECTIVE

We hypothesized that cardioprotection by GLP-1 is achieved through increased glucose availability and utilization and aimed to assess the effect of exenatide, a synthetic GLP-1 receptor agonist, on myocardial glucose uptake (MGU), myocardial glucose transport, and myocardial blood flow (MBF).

DESIGN AND METHODS

We conducted a randomized, double-blinded, placebo-controlled crossover study in eight male, insulin-naive, type 2 diabetes mellitus patients without coronary artery disease. Positron emission tomography was used to determine the effect of exenatide on MGU and MBF during a pituitary-pancreatic hyperglycemic clamp with (18)F-fluorodeoxyglucose and (13)N-ammonia as tracers.

RESULTS

Overall, exenatide did not alter MGU. However, regression analysis revealed that exenatide altered initial clearance of glucose over the membrane of cardiomyocytes and MGU, depending on the level of insulin resistance (P = 0.017 and 0.010, respectively). Exenatide increased MBF from 0.73 ± 0.094 to 0.85 ± 0.091 ml/g · min (P = 0.0056). Except for an increase in C-peptide levels, no differences in circulating hormones or metabolites were found.

CONCLUSIONS

The action of exenatide as an activator or inhibitor of the glucose transport and glucose uptake in cardiomyocytes is dependent on baseline activity of glucose transport and insulin resistance. Exenatide increases MBF without changing MGU.

Insulin dose-response studies in severely insulin-resistant type 2 diabetes--evidence for effectiveness of very high insulin doses

AIM

To combat diabetic complications strict glycaemic control is desirable in type 2 diabetes, but some patients are severely insulin resistant and it is not known whether high doses of insulin are effective. This study was designed to determine the acute dose-response effects of insulin in patients with type 2 diabetes and severe insulin resistance.

METHODS

We included eight insulin-resistant (mean insulin dose: 186 IU/day; body mass index: 35) subjects with type 2 diabetes in a single-blinded, randomized crossover study. Each subject was studied on two occasions. On each occasion, subjects underwent two 3-h hyperinsulinaemic euglycaemic clamps. The subjects were randomized to two low-dose insulin infusions (0.5 and 1.5 mU/kg/min in random order) on one occasion and to two high-dose insulin infusions (3.0 and 5.0 mU/kg/min in random order) on another occasion.

RESULTS

On all occasions, steady-state glucose infusion rates (SSGIRs) were accomplished and we observed a clear dose-response relationship with GIR values of 0.4 ± 0.2 (s.e.), 2.6 ± 0.6, 3.7 ± 0.8 and 4.9 ± 0.9 mg/kg/min during the 0.5, 1.5, 3.0 and 5.0 mU/kg/min insulin infusions, respectively (p < 0.001). Likewise, there was a dose-dependent suppression of endogenous glucose production (EGP) (p < 0.009), plasma free fatty acids (FFAs) (p < 0.001) and plasma glucagon (p = 0.001).

CONCLUSIONS

Our results show that the insulin dose response in terms of GIR and EGP is preserved for insulin doses corresponding to >800 IU/day, suggesting effectiveness of very high insulin doses in severely insulin-resistant subjects.

Cyclosporin and tacrolimus impair insulin secretion and transcriptional regulation in INS-1E beta-cells

BACKGROUND AND PURPOSE

Introducing the calcineurin inhibitors cyclosporin (CsA) and tacrolimus (Tac) has improved the outcome of organ transplants, but complications such as new onset diabetes mellitus after transplantation (NODAT) decrease survival rates.

EXPERIMENTAL APPROACH

We sought, in a beta-cell culture model, to elucidate the pathogenic mechanisms behind NODAT and the relative contribution of the calcineurin inhibitors. INS-1E cells were incubated at basal and stimulatory glucose concentrations, while exposed to pharmacologically relevant doses of CsA, Tac and vehicle for 6 or 24 h.

RESULTS

Tac inhibited basal (P < 0.05), but not glucose-stimulated insulin secretion (GSIS) after 6 h of exposure. After 24 h, both agents inhibited basal and GSIS (P < 0.05). Calcineurin phosphatase activity was decreased by both drugs during all conditions. Apoptosis was only seen with CsA treatment, which also induced a slight suppression of calcineurin and insulin mRNA, as well as increased levels of the sterol receptor element binding protein (SREBP)-1c, a transcription factor thought to suppress genes essential for beta-cell function and induce insulin resistance. Expression levels of nuclear factor of activated T-cells (NFAT)-c1, -c2, -c3 and -c4 were not decreased notably by either drug.

CONCLUSIONS AND IMPLICATIONS

Tac had acute inhibitory effects on basal insulin secretion, but prolonged exposure (24 h) to Tac or CsA revealed similar suppression of insulin secretion. These prolonged effects were mirrored by a total inhibition of calcineurin activity in beta-cells. CsA showed greater inhibition of beta-cell survival and transcriptional markers, essential for beta-cell function.

Comparison of two sulfonylureas with high and low myocardial K(ATP) channel affinity on myocardial infarct size and metabolism in a rat model of type 2 diabetes

AIMS/HYPOTHESIS

Sulfonylureas (SUs) may impair outcome in patients with acute coronary syndrome. Most experimental studies of the myocardial effects of SU treatment are performed in non-diabetic models. We compared the effect of two widely used SUs, glibenclamide (gb) and gliclazide (gc), with high and low myocardial K(ATP) channel affinity, respectively, at therapeutic concentrations on infarct size, left ventricular (LV) function and myocardial glycogen, lactate and alanine content before and after ischaemia/reperfusion (I/R).

METHODS

Non-diabetic Wistar and diabetic Goto-Kakizaki rat hearts were investigated in a Langendorff preparation. Gb (0.1 μmol/l) and gc (1.0 μmol/l) were administrated throughout the study. Infarct size was evaluated after 120 min of reperfusion. Myocardial metabolite content was measured before and after ischaemia.

RESULTS

Infarct size was smaller in diabetic hearts than in non-diabetic hearts (0.33 ± 0.03 vs 0.51 ± 0.05, p < 0.05). Gb increased infarct size (0.54 ± 0.04 vs 0.33 ± 0.03, p < 0.05) and reduced post-ischaemic LV developed pressure (60 ± 3 vs 76 ± 3 mmHg, p < 0.05) and coronary flow (4.9 ± 0.5 vs 7.1 ± 0.4 ml min(-1) g(-1), p < 0.05) in gb-treated diabetic rats compared with untreated diabetic rats. On comparing gb-treated diabetic rats with untreated diabetic rats, glycogen content was reduced before (9.1 ± 0.6 vs 13.6 ± 1.0 nmol/mg wet weight, p < 0.01) and after ischaemia (0.9 ± 0.2 vs 1.8 ± 0.2 nmol/mg wet weight, p < 0.05), and lactate (4.8 ± 0.4 vs 3.2 ± 0.3 nmol/mg wet weight, p < 0.01) and alanine (1.38 ± 0.12 vs 0.96 ± 0.09 nmol/mg wet weight, p < 0.05) contents were increased during reperfusion. Gc-treatment of diabetic and non-diabetic rats did not affect any of the measured variables.

CONCLUSIONS/INTERPRETATIONS

Gb, but not gc, exacerbates I/R injury and deteriorates LV function in diabetic hearts. These effects of gb on diabetic hearts may be due to detrimental effects on myocardial carbohydrate metabolism.

Zinc, zinc transporters and diabetes

The role of zinc in islet function has recently achieved new attention as a consequence of the identification of zinc transporter 8 (ZNT8) in islets, and the association of mutations in the gene for this zinc transporter with glucose intolerance and type 2 diabetes. ZNT8 is also an autoantigen associated with the appearance of type 1 diabetes. A number of experimental models have been employed to suggest how ZNT8 and other zinc transporters regulate beta cell insulin processing and possibly secretion. An additional role for the zinc transporters in regulating alpha cell function has been suggested. In this issue of Diabetologia, Wijesekara and colleagues, using a cell-specific Znt8 (also known as Slc30a8) knockout model, demonstrate that beta cell insulin processing and glucose tolerance is negatively affected after beta cell knock out of Znt8, whereas Znt8 knockout in alpha cells seems to have little effect on glucagon secretion or glucose tolerance. Although we are yet to see the therapeutic potential of these new findings, the area represents a field through which manipulation of islet function may eventually be possible.

Similarity of pharmacodynamic effects of a single injection of insulin glargine, insulin detemir and NPH insulin on glucose metabolism assessed by 24-h euglycaemic clamp studies in healthy humans

AIMS

Two long-acting insulin analogues, insulin glargine and insulin detemir, have been developed as alternatives to neutral protamine Hagedorn (NPH) insulin, which has been the preferred basal insulin preparation for decades. The aim was to directly compare the pharmacodynamic properties of the long-acting insulin analogues and NPH insulin after a single subcutaneous injection.

METHODS

The study was conducted as a double-blind, controlled, three-arm, crossover study including 10 healthy lean male volunteers. On three different occasions, each subject was challenged with 0.4 U kg(-1) of either insulin glargine, insulin detemir or NPH insulin. Plasma glucose was maintained at 0.3 mmol l(-1) below fasting level by glucose clamping for 24 h. C-peptide, insulin, free fatty acids (FFAs) and counter regulatory hormones were measured throughout the clamp period, whereas endogenous glucose release (EGR) was assessed by isotope dilution technique (3-(3)H-glucose).

RESULTS

The mean glucose infusion rate (GIR)-time profiles revealed no significant differences between the three preparations in the primary endpoints: Maximal GIR of approximately 3.4 mg kg(-1) min(-1) (P = 0.68), time to maximal GIR of approximately 10 h (TR(max)) (P = 0.35) and area under the GIR curve (GIR(AUC)) (P = 0.81). Compared with the other insulin preparations, EGR (see above)was lower for insulin detemir at the beginning of the clamp period (330-360 min) (P = 0.007) while GIR was lower (P = 0.005) and FFA concentrations were higher (P = 0.005) during the last 4 h of the clamp.

CONCLUSIONS

In this experimental design, only minor pharmacodynamic differences were demonstrated between insulin detemir, insulin glargine and NPH insulin.

Type of preadmission glucose-lowering treatment and prognosis among patients hospitalised with myocardial infarction: a nationwide follow-up study

AIMS/HYPOTHESIS

We examined whether the type of preadmission glucose-lowering treatments explained differences in mortality rate and risk of readmission with myocardial infarction (MI) and heart failure following first-time hospitalisation for MI in patients with type 2 diabetes mellitus.

METHODS

We conducted a nationwide population-based follow-up study among all Danish patients hospitalised with first-time MI from 1996 to 2004. Data on use of glucose-lowering drugs and other medications, comorbidities, socioeconomic status, laboratory findings, readmission with MI and heart failure, and death were obtained from medical databases. We computed mortality rates and rates of MI and heart failure readmission, according to type of glucose-lowering treatment and used Cox's proportional hazards regression analysis to compute hazard ratios (HRs) as estimates of relative risks.

RESULTS

We identified 8,494 MI patients with type 2 diabetes mellitus. The overall cumulative 30 day and 1 year mortality rates were 22.2 and 36.6%, respectively. Patients not receiving any glucose-lowering drugs (adjusted 30 day HR: 0.79, 95% CI: 0.57-1.10) and users of any combination (adjusted 30 day HR: 1.43, 95% CI: 0.98-2.09) had the lowest and highest mortality rates, respectively, when compared with users of sulfonylureas. We found that glycaemic control had no impact on the risk estimates in a subanalysis including biochemical laboratory data. We found no differences in the risk of new MI and heart failure between the different glucose-lowering agents.

CONCLUSIONS/INTERPRETATION

Type of preadmission glucose-lowering treatment in monotherapy is not associated with substantial differences in prognosis following hospitalisation with MI. However, patients treated with any combination had increased mortality rates.

Amyloid plaques arise from zinc-enriched cortical layers in APP/PS1 transgenic mice and are paradoxically enlarged with dietary zinc deficiency

The ZnT3 zinc transporter is uniquely expressed in cortical glutamatergic synapses where it organizes zinc release into the synaptic cleft and mediates beta-amyloid deposition in transgenic mice. We studied the association of zinc in plaques in relation to cytoarchitectural zinc localization in the APP/PS1 transgenic mouse model of Alzheimer's disease. The effects of low dietary zinc for 3 months upon brain pathology were also studied. We determined that synaptic zinc distribution within cortical layers is paralleled by amyloid burden, which is heaviest for both in layers 2-3 and 5. ZnT3 immunoreactivity is prominent in dystrophic neurites within amyloid plaques. Low dietary zinc caused a significant 25% increase in total plaque volume in Alzheimer's mice using stereological measures. The level of oxidized proteins in brain tissue did not changed in animals on a zinc-deficient diet compared with controls. No obvious changes were observed in the autometallographic pattern of zinc-enriched terminals in the neocortex or in the expression levels of zinc transporters, zinc importers or metallothioneins. A small decrease in plasma zinc induced by the low-zinc diet was consistent with the subclinical zinc deficiency that is common in older human populations. While the mechanism remains uncertain, our findings indicate that subclinical zinc deficiency may be a risk factor for Alzheimer's pathology.

Zinc ions in the endocrine and exocrine pancreas of zinc deficient rats

OBJECTIVE

Zinc deficiency is a problem world-wide. Zinc and insulin are intimately related, and a reduced zinc intake may affect glucose metabolism. The present study investigates how subclinical zinc deficiency in rats affects glucose metabolism and zinc distribution in the pancreas.

METHODS

Glucose metabolism was evaluated by blood-glucose, serum insulin, homeostasis model assessment (HOMA), and intraperitoneal glucose tolerance tests. Immersion zinc-sulphide autometallography (iZnSAMG) was used to describe zinc ion distribution.

RESULTS

After 4 weeks on a zinc deficient diet (<10 ppm), the zinc deficient rats had a slightly impaired glucose metabolism characterized by significantly increased blood-glucose levels. No differences in serum insulin, insulin resistance, beta-cell function were observed. The zinc deficient rats had significantly decreased serum zinc without any clinical signs of zinc deficiency. Zinc ion staining intensity of the islets of Langerhans was unaffected by the zinc deficiency. In contrast, the acinar cells in the exocrine pancreas appeared depleted of iZnSAMG grains in the zinc deficient rats when compared with their controls. Though statistically non-significant, a reduction in total zinc of the pancreas was found.

CONCLUSIONS

The present findings suggest that the endocrine pancreas is able to compensate for the subclinical zinc deficiency as it maintains an adequate zinc ion level in the secretory vesicles for insulin storage. The exocrine pancreas lacks this ability; it exhibits decreased levels of zinc ion staining as a consequence of 4 weeks of reduced zinc intake.

Risk and Short-Term Prognosis of Myocardial Infarction Among Users of Antidiabetic Drugs

Old sulphonylureas have been linked with adverse cardiovascular effects; however, data on the clinical implications are sparse. We examined the association between use of sulphonylureas and other antidiabetic drugs and the risk and case fatality rate (CFR) of myocardial infarction (MI) in a population-based case-control and follow-up study, respectively. A total of 6738 cases of first-time MI and 67,374 age- and gender-matched population controls were identified from the Hospital Discharge Registry and the Civil Registration System of North Jutland County, Denmark, in the period 1994 through 2002. Prescriptions for antidiabetic drugs before the index date were retrieved from a prescription database. We estimated odds ratios (ORs) of MI (case-control study) and 30-day CFR (follow-up study) associated with antidiabetic drug use adjusted for possible confounding factors and using nondiabetic subjects as the reference group. The risk of MI appeared higher among users of old sulphonylureas (adjusted OR, 2.07; 95% confidence interval (CI), 1.81-2.37) than among users of new sulphonylureas (adjusted OR, 1.36; 95% CI, 1.01-1.84). The adjusted ORs among users of nonsulphonylurea oral antidiabetic drugs, insulin, and patients with diabetes not receiving pharmacotherapy were 1.38 (95% CI, 0.90-2.11), 2.56 (95% CI, 2.16-3.03), and 3.51 (95% CI, 2.92-4.22), respectively. The overall 30-day CFR was 24.6%, but varied between 9.5% and 37.0% among the different categories. New sulphonylureas may be associated with a lower risk of MI than old sulphonylureas. Furthermore, the 30-day CFR may vary according to type of antidiabetic drug. These differences indicate the need for further examination of the cardiovascular safety of antidiabetic drugs.

Real-time PCR: housekeeping genes in the INS-1E beta-cell line

Investigation of gene expression is a developing area with several methods available. One method is quantitative PCR. A major pitfall in quantitative PCR is the normalisation procedure of the gene expression. Many experiments include a housekeeping gene, some use RNA concentration, and others use a geometric mean of several internal, stably expressed genes. This study demonstrates that real-time-PCR results differ with varying housekeeping genes and analysis protocols when applied to insulin-secreting INS-1E cells derived from the pancreas and stimulated by DEDTC (diethyldithiocarbamate, a zinc chelator) and GLP-1.

Zinc fluxes during acute and chronic exposure of INS-1E cells to increasing glucose levels

Zinc in beta-cell secretory vesicles is essential for insulin hexamerization, and tight vesicular zinc regulation is mandatory. Little is known about zinc ion fluxes across the secretory vesicle membrane and the influence of changes in the extracellular environment on vesicular zinc. Our study aim was to investigate the effect of acute and chronic exposure to various glucose concentrations on zinc in secretory vesicles, the relation between zinc and insulin, and the presence of two zinc transporters, ZnT1 and ZnT4, in INS-1E cells. Zinc ions were demonstrated and semi-quantified using zinc-sulfide autometallography. Insulin content and secreted insulin were measured. Measurements were made on INS-1E cells after exposure to 2.0, 6.6, 16.7, and 24.6 mmol/l glucose for 1, 24, and 96 hours. 1h: Increasing glucose resulted in no changes in intravesicular zinc ions at 2, and 24.6 mmol/l glucose, but a slight increase at 16.7 mmol/l glucose. 24 and 96 h: Increasing glucose led to decreased vesicular zinc ion content accompanied by a decrease in insulin content. ZnT1 and ZnT4 were present in the cytoplasm. Our results demonstrate that intra-vesicular zinc ions respond to changes in the extra-cellolar glucose concentration, especially during chronic high glucose concentrations, where the content of vesicular zinc ions decreases.

Zinc ions in beta-cells of obese, insulin-resistant, and type 2 diabetic rats traced by autometallography

Zinc ions in the secretory granules of beta-cells are known to glue insulin molecules, creating osmotically stable hexamers. When the secretory granules open to the surface, the zinc ion pressure decreases rapidly and pH levels change from acid to physiological, which results in free insulin monomers and zinc ions. The released zinc ions have been suggested to be involved in a paracrine regulation of alpha- and beta-cells. Since zinc is intimately involved in insulin metabolism and because zinc homeostasis is known to be disturbed in type 2 diabetes, we decided to study the ultrastructural localisation of zinc ions in insulin-resistant and type 2 diabetic rats as compared to controls. By means of autometallography, the only method available for demonstrating zinc ions at ultrastructural levels, we found zinc ions in the secretory granules and adjacent to the plasma membrane. The membrane-related staining outside the plasma membrane reflects release of zinc ions during exocytosis. No apparent difference was found in the ultrastructural localisation of zinc ions when we compared the obese Zucker (fa/fa) rats, representing the insulin resistance syndrome, and the GK rats, representing type 2 diabetes, with controls. This suggests that the ultrastructural localisation of zinc ions is unaffected by the development of type 2 diabetes in rats in a steady state of glycaemia.

Autometallography allows ultrastructural monitoring of zinc in the endocrine pancreas

Zinc is intimately involved in insulin metabolism, its major known role being the binding of insulin in osmotically stable hexamers in beta-cell granules. To investigate the anatomical distribution of zinc ions necessary for insulin binding we examined the rat pancreas by autometallography (AMG). AMG demonstrates chelatable zinc and is a sensitive marker for zinc in vesicles and also a surrogate marker for recently described zinc pumps regulating intravesicular zinc metabolism. Zinc ions were found in alpha- and beta-cell granules, primarily in the periphery of the granules. Only occasionally was zinc seen in other islet cell types. AMG allows the study of the microscopic and ultrastructural localisation of free zinc ions in the pancreas. The applicability of the method at the ultrastructural level in particular makes AMG a very sensitive tool in future studies on the role of zinc ions in the pancreas.

Histochemical tracing of bismuth in Helicobacter pylori after in vitro exposure to bismuth citrate

BACKGROUND

Bismuth-containing drugs are widely used in the treatment of Helicobacter pylori associated peptic ulcer. The mechanism of action of bismuth salts is, however, not fully understood, and at present no histochemical techniques for the demonstration of bismuth in H. pylori are available. The aims were to present a histochemical method for the detection of bismuth in H. pylori and to demonstrate bismuth uptake in H. pylori after in vitro exposure to bismuth citrate.

METHODS

H. pylori cultures (the strain used in this study was CCUG 17874), were exposed to bismuth citrate at different concentrations (0, 4.6, 80, 200 microM) and for different lengths of time (0 min, 15 min, 1 h, 24 h, 48 h). The samples were fixed in glutaraldehyde, centrifuged, and exposed to autometallographic (AMG) development in order to detect bismuth histochemically.

RESULTS

A detailed protocol on the AMG bismuth technique on H. pylori exposed to bismuth in vitro is given. This method results in easily detectable AMG grains of silver enhanced bismuth particles at the electron microscopical level, and shows that bismuth accumulates in H. pylori, predominantly near the wall of the bacteria. Bismuth uptake is followed by bacterial degeneration.

CONCLUSION

The present technique with its ability to trace bismuth constitutes a valuable tool in the efforts of clarifying the mechanism of action of bismuth on H. pylori, and supports the notion that bismuth has an antimicrobial activity in itself.

Uptake of bismuth in motor neurons of mice after single oral doses of bismuth compounds

Bismuth, a component of many gastrointestinal medications, is a heavy metal little studied as regards nervous system uptake. We were interested to see if low doses of intragastric bismuth entered the nervous system, and if dietary selenium influenced the amount of bismuth detected. Mice were given 40 to 1200 mg/kg of bismuth subnitrate (BSN), bismuth subsalicylate (BSS), colloidal bismuth subcitrate (CBS), or ranitidine bismuth citrate (RBC) intragastrically. Mice on low- or high-selenium diets were given 4 to 32 mg/kg of bismuth from RBC. One week later, sections of nervous tissue were stained with autometallography to detect bismuth grains (Bi(AMG)). Bismuth was found in neurons with axons outside of the nervous system, in particular motor neurons, and in cells outside the blood-brain barrier. The lowest bismuth dose which resulted in Bi(AMG) in motor neurons was 696 mg/kg from BSN, 57 mg/kg from BSS, 29 mg/kg from CBS, and 26 mg/kg from RBC. No bismuth was seen in motor neurons of mice on the low-selenium diet. Intragastric doses of bismuth therefore enter mouse motor neurons, and the amount detectable varies with dietary selenium.

Fractures in patients with primary idiopathic hypothyroidism

AIM

To study fracture risk and risk factors for fractures in patients with primary idiopathic hypothyroidism (ICD 10: E03.9).

DESIGN

Historical follow-up.

MATERIAL AND METHODS

A self-administered questionnaire was issued to 628 patients with primary idiopathic levothyroxine-substituted hypothyroidism. A total of 412 (65.6%) responded and of these, 408 could be analyzed. The 408 respondents were age- (+/- 5 years) and gender-matched with 408 normal controls randomly selected from the background population who responded to the same questionnaire.

RESULTS

Overall fracture risk was increased in patients compared to controls (relative risk: RR = 1.6, 95% CI: 1.0-2.5). However, the increase was temporary and limited to the period within the first 2 years after the diagnosis of hypothyroidism (RR = 3.1, 95% CI: 1.4-7.0). Before the diagnosis and more than 2 years after the diagnosis, the fracture risk in patients did not deviate from that of the controls. The increase in fracture risk was only significant in the age group above 50 years (RR = 1.8, 95% CI: 1-3.2), and was limited to the forearms (RR = 3.0, 95% CI: 1.4-6.3 for the entire patient population).

CONCLUSIONS

There was a temporary increase in fracture risk within the first 2 years after diagnosis of primary idiopathic hypothyroidism. The fracture risk was mainly increased in the age group above 50 years, and the increased risk was limited to the forearms.

Tissue uptake of bismuth from shotgun pellets

Shotgun pellets containing bismuth have been suggested to be less environmentally toxic than those containing other metals. We sought to find if bismuth from shotgun pellets embedded within an animal enters the tissues of that animal. Five bismuth-containing shotgun pellets were placed intraperitoneally into adult mice. Four or 9 weeks later the tissue distribution of bismuth was examined histologically using silver lactate autometallography. Bismuth was seen in the nervous system of the mice, either in cells with processes outside the nervous system or in cells not protected by the blood-brain barrier. Bismuth was also seen in the kidney, liver, spleen, and lung. The amount of bismuth within tissues varied widely between animals at both time intervals. Bismuth from shotgun pellets enters the tissues of mice, with some mice taking up more bismuth than others. Some animals wounded with bismuth pellets are therefore likely to accumulate large amounts of potentially toxic bismuth in their tissues.

Biochemical markers of bone metabolism reflect osteoclastic and osteoblastic activity in multiple myeloma

In order to evaluate the use of recently developed assays of bone metabolism in multiple myeloma we performed a histomorphometric study of bone biopsies in 16 myeloma patients. Furthermore, we measured the levels of interleukin-6 (IL-6), soluble IL-6 receptor (IL-6sR), IL-1beta, tumour necrosis factor (TNF) alpha, TNFbeta, and transforming growth factor (TGF) beta in marrow plasma aspirated from the biopsy area. MARKERS OF BONE RESORPTION: The N-terminal telopeptide of collagen I (Ntx) in urine showed a strong positive correlation with the dynamic histomorphometric indices of bone resorption (r=0.68-0.72). Slightly weaker correlations were observed between the dynamic indices of bone resorption and the C-terminal telopeptide of collagen I (ICTP) in serum (r= 0.57-0.62) and deoxypyridinoline (Dpyr) in urine (r= 0.54), whereas urinary pyridinoline (Pyr) did not correlate with the histomorphometric findings. MARKERS OF BONE FORMATION: Serum C-terminal propeptide of procollagen I (PICP) and serum bone-specific alkaline phosphatase (bAP) showed significant correlations with the dynamic parameters of bone formation (r=0.57-0.58), whereas serum osteocalcin and serum total AP did not. CYTOKINES: Highly significant correlations were observed between marrow IL-6 and rates of bone resorption and activation frequency (r=0.76-0.82) and with serum ICTP (r=0.63). Minor, but also significant correlations were observed between the resorptive indices and IL-6sR and IL-1beta. The data indicate that measurements of the biochemical markers of bone metabolism may be useful in monitoring myeloma bone disease, and might thus be of use for dose titration of bisphosphonate therapy.

Histochemical tracing of bismuth in testis from rats exposed intraperitoneally to bismuth subnitrate

The histochemical silver amplification technique autometallography (AMG), was used to trace bismuth in the testis of Wistar rats injected intraperitoneally with bismuth subnitrate. In the seminiferous tubules, bismuth was located in lysosomes of Sertoli cells closely associated with heads of spermatids in the late stages of the spermatogenesis, i.e. shortly before the release of Step 19 spermatids in Stage XIII. No bismuth-specific AMG silver grains were detected in the spermatogenic cell line. However, tails of free sperm cells located in the tubular lumen showed autometallographic grains in close contact to the nine outer microtubule doublets in the axonema. Leydig cells concentrated huge amounts of AMG-bismuth in their lysosomes. Furthermore, parallel exposure to selenium significantly increased the amount of histochemically traceable bismuth in the rat testis.

Hormone replacement therapy prevents osteoclastic hyperactivity: A histomorphometric study in early postmenopausal women

In a randomized, double blind, clinical prospective trial comprising 35 women treated with either hormone replacement therapy (HRT) (cyclic estradiol/norethisterone acetate) or placebo we performed histomorphometric studies on paired bone biopsies obtained before and after 2 years of treatment. Untreated women developed a progressively more negative balance at individual bone multicellular units (BMUs) (i.e., wall thickness-erosion depth) (2.2 +/- 1.7 microm vs. -5.7 +/- 1.4 microm; p < 0.01), while women on HRT displayed preservation of bone balance (2.4 +/- 2.4 microm vs. 2.5 +/- 2.5 microm; NS). No significant differences in wall thickness between the two groups were demonstrable, but the untreated women developed a pronounced increase in erosion depth over 2 years (46.9 +/- 1.8 microm vs. 52.0 +/- 1.9 microm; p < 0.05), while the HRT group revealed no change (47.8 +/- 2.7 microm vs. 44.6 +/- 1.7 microm; NS). Furthermore, the placebo group displayed an increased osteoclastic erosion depth (17.8 +/- 1.6 microm vs. 25.0 +/- 1.7 microm; p < 0.001), compared with unchanged values in the HRT group (20.0 +/- 1.6 microm vs. 16.9 +/- 1.4 microm/day; NS). While the placebo group revealed a slight increase in volume referent resorption rate (35 +/- 8% vs. 38 +/- 8%; NS) the HRT group revealed a pronounced decrease (46 +/- 8% vs. 28 +/- 5%; p < 0.05). No significant changes in marrow star volume (an index of trabecular perforations) were demonstrable in either group. Our results demonstrate that bone remodeling in early postmenopausal women is characterized by progressive osteoclastic hyperactivity, which is reduced by cyclic HRT. This reduction of resorptive activity at the BMU level after HRT seems to precede the reduction in activation frequency demonstrated in previous studies on older postmenopausal women.

[Metaphyseal chondrodysplasia]

Metaphyseal chondrodysplasia (MCD) is a heterogeneous group of diseases characterised by defective enchondral ossification, leading to metaphyseal changes. The different types of MCD can be distinguished by clinical findings, radiology and genetic tests. Based on a case story with MCD, pancreatic insufficiency and granulocytopenia (Shwachman's syndrome), we review the most common types of MCD with regard to clinical manifestations, radiological findings, and genetic background.

Long-term oral pamidronate treatment inhibits osteoclastic bone resorption and bone turnover without affecting osteoblastic function in multiple myeloma

This study was performed as a cross-sectional substudy to the Danish-Swedish Pamidronate Study, a randomized placebo-controlled multicentre trial in multiple myeloma. The purpose was to evaluate the biological effects of long-term treatment with oral pamidronate 300 mg daily on bone metabolism by using histomorphometry and analysis of cytokines and biochemical markers of bone turnover. Sixteen patients were included after median 27.5 months of protocolized treatment; 10 patients received active treatment and 6 patients placebo. When compared with placebo, pamidronate treatment was associated with: (a) marked decreased osteoclastic resorption rate (0.86+/-0.59 microm/d vs. 5.7+/-5.0 microm/d, p=0.002), and diminished activation frequency (0.20+/-0.18 yr(-1) vs. 0.72+/-0.55 yr(-1), p=0.014); (b) compensatory reduced volume referent bone formation rate (0.17+/-0.21 yr(-1) vs. 0.71+/-0.54 yr(-1), p=0.007), but unaltered mineral appositional rate; (c) neutral (-0.66+/-5.6 mm) vs. negative (-2.15+/-2.2 microm, p=0.013) bone balance per remodelling cycle; (d) higher trabecular bone volume (21.0+/-6.2% vs. 13.0+/-3.7%, p=0.01); (e) suppressed urinary excretion and serum levels of some of the biochemical markers of bone metabolism; and (f) significant reduction of circulating soluble interleukin-6 receptor (IL-6sR) (25.9+/-4.1 ng/ml vs. 32.1+/-6.6 ng/ml, p=0.04), and (g) a uniform tendency of lower serum and marrow plasma levels of IL-6, IL-1beta, and TNFalpha. Thus oral pamidronate was absorbed in biologically active amounts, and reduced overall bone resorption and bone turnover without impairing osteoblastic bone formation. The observation that cytokine and cytokine receptor levels were reduced extends the possible and potential beneficial actions of bisphosphonates in multiple myeloma.

Inflammatory bowel disease and osteoporosis

The relation between inflammatory bowel disease (IBD) and osteoporosis has received increasing attention during the past decade. The prevalence of low bone mass in patients with IBD has been reported to be more than 50%. The development of a quick non-invasive method to diagnose osteoporosis (dual-energy X-ray absorptiometry) provides a practical tool to identify the patient who needs special attention. The aetiology of the bone disease in patients with IBD has still not been elucidated, but corticosteroids may play a major role. Studies on the prevention/treatment of IBD-related osteoporosis are scarce. In a single uncontrolled study hormone replacement therapy proved effective in preventing bone loss in peri- and post-menopausal women with IBD. A placebo-controlled study showed that supplementation with calcium and vitamin D prevents bone loss in patients with Crohn's disease. The present paper reviews our current knowledge on the mechanisms and epidemiology of IBD-related bone disease.

Influence of mercuric chloride on resistance to generalized infection with herpes simplex virus type 2 in mice

The effect of mercuric chloride on resistance to generalized infection with herpes simplex virus type 2 (HSV-2) in mice was studied. The severity of the infection was evaluated by the amount of infectious virus in the liver. Mercury at a single dose of 20 micrograms aggravated the infection, and neither increasing the single dose to 80 micrograms nor giving repeated doses of 20 micrograms further intensified the infection. Examination of the course of infection after mercury exposure revealed an increased virus replication and dissemination during the first days of the infection, indicating that the early, nonspecific defence mechanisms were affected. Virus clearance and elimination, which is mediated by specific immunity, seemed not to be influenced. Examination of cells from the peritoneal cavity and of livers from virus-infected mice showed that mercury detectable by autometallography was exclusively found in mature peritoneal macrophages and in Kupffer cells of the liver. Inflammatory cells, recruited to the peritoneal cavity or infiltrating the infectious foci of the liver, did not show any mercury deposits. Attempts to demonstrate an effect in vivo of mercury on potential antiviral macrophage functions like interferon-alpha/beta (IFN-alpha/beta) and tumour necrosis factor-alpha (TNF-alpha) secretion and oxidative burst capacity were not successful, possibly because recruited, inflammatory cells, which have not been exposed to the high mercury concentrations at the site of injection, take over these functions of intoxicated macrophages.

Lipoprotein(a) and oxygen free radicals in survivors of acute myocardial infarction: effects of captopril

Long-term treatment of survivors of an acute myocardial infarction with angiotensin-converting enzyme inhibitors has a beneficial impact on their long-term outcome. We tested the hypothesis that captopril could reductively cleave the lipoprotein(a) molecule and in addition act as a scavenger of oxygen free radicals. In a double-blind trial, 20 patients were randomized to receive either captopril 50 mg daily or corresponding placebo. patients were followed for a period of 30 days. Blood samples were drawn prior to randomization and after 30 days of treatment. Plasma concentrations of lipoprotein(a) and malondialdehyde were evaluated. Captopril treatment produced a significant reduction in plasma content of lipoprotein(a) ( < 0.05) and at day 30 the plasma content of lipoprotein(a) was also significantly lower than that in the placebo group (p < 0.05). furthermore, on day 30 plasma concentrations of malondialdehyde, an indicator of oxidative damage, were significantly lower in the captopril group when compared to baseline values and corresponding placebo group values (p < 0.05). The observed effect of captopril treatment on lipoprotein(a) and malondialdehyde might be ascribed to the sulfhydryl group in the captopril molecule.

Decreased activation of the respiratory burst in neutrophils from AIDS patients with previous Pneumocystis carinii pneumonia

Neutrophils from human immunodeficiency virus (HIV)-negative blood donors, asymptomatic HIV-positive patients, AIDS patients with previous Pneumocystis carinii pneumonia (PCP), and AIDS patients without previous PCP were compared for their ability to activate the respiratory burst, measured as luminol-amplified chemiluminescence. P. carinii, Staphylococcus aureus, phorbol-12-myristate-13-acetate, and FMLP were used to stimulate the neutrophils. When stimulated with P. carinii, neutrophils from PCP patients had a significantly lower response than the other groups, whereas no difference was found when S aureus was used. A somewhat but not significantly lower response to P. carinii was also seen in non-PCP patients compared with HIV-negative donors. Priming of the neutrophils with recombinant granulocyte colony-stimulating factor (G-CSF) or recombinant human granulocyte-macrophage (GM)-CSF corrected this defect. A similar effect of these cytokines was seen on phagocytosis, whereas the chemiluminescence in unprimed cells did not correlate with phagocytosis.

Epidemiology of osteoporosis. Implications for drug therapy

Osteoporosis represents a major health problem. Fractures secondary to decreased bone mass and disrupted bone structure vastly increase morbidity in postmenopausal women, and morbidity as well as mortality in elderly people of either sex. Prophylaxis is possible, and indeed appears to be vital to ensure a high peak bone mass. Peak bone mass is reached during the second or third decade of life, i.e. 20 to 50 years before the appearance of osteoporotic fractures. Exercise and a sufficient calcium intake are possible measures in the early years. During menopause, estrogen replacement therapy will delay the accelerated bone loss and, most likely, also osteoporotic fractures. In established osteoporosis, a number of well documented therapies are now available. Depending on the age of the patient, bisphosphonates, calcitriol or other vitamin D preparations, calcium and calcitonin may be employed. This article reviews the epidemiology of osteoporotic fractures with special reference to the therapeutic implications.

Pneumocystis carinii-induced activation of the respiratory burst in human monocytes and macrophages

Human monocytes and monocyte-derived macrophages were studied for their ability to phagocytose Pneumocystis carinii and produce superoxide (O2-) during the process. One x 10(6) freshly isolated monocytes, incubated with 0.1-3.75 x 10(6) P. carinii cysts, increased O2- production in a dose-related way. Antibodies were essential for the process since opsonized, but not unopsonized, pneumocysts induced O2- production significantly above the response obtained by lung tissue from rats (10.7 and 4.9 versus 3.0 fmol/cell per 90 min). The difference between pneumocysts opsonized in untreated versus complement-depleted serum was not significant (10.7 versus 12.6 fmol/cell per 90 min). Monocyte-derived macrophages also activated the respiratory burst when stimulated with pneumocysts, and this effect could be significantly increased, from 4.2 to 8.8 fmol/cell per 90 min, when cells were primed with interferon-gamma (IFN-gamma). Cells primed with IL-3 also increased O2- production, though to a lesser extent. In contrast, granulocyte-macrophage colony-stimulating factor (GM-CSF) had only a small effect on the respiratory burst in cells stimulated with P. carinii. Priming with IFN-gamma increased the rate of phagocytosis in macrophages. After incubation for 90 min or more, however, the percentage of cells with phagocytic vacuoles was only slightly higher in IFN-gamma-primed cells. When examined by electron microscopy (EM), most vacuoles contained partially or totally degraded pneumocysts. In conclusion, we have demonstrated the ability of monocytes and monocyte-derived macrophages to ingest and degrade pneumocysts, activating the respiratory burst during the process.

Phagocytosis and stimulation of the respiratory burst in neutrophils by Pneumocystis carinii

Phagocytosis and superoxide production of neutrophils stimulated with Pneumocystis carinii were studied using P. carinii obtained from rats and neutrophils and serum from healthy blood donors. Superoxide generation increased in a dose-related way to the number of pneumocysts added and was significantly higher when the parasites were opsonized. The use of heat-inactivated serum for opsonization reduced superoxide production somewhat, but not significantly. Preincubation of neutrophils with recombinant human granulocyte-macrophage colony-stimulating factor (rHuGM-CSF) increased superoxide production in neutrophils stimulated with pneumocysts from 7.0 to 9.6 fmol/cell/20 min; however, the production in unstimulated cells increased by the same amount. Activation of the respiratory burst was paralleled by phagocytosis, and very few phagocytic vacuoles were found in neutrophils stimulated with unopsonized pneumocysts. By electron microscopy, various stages of cyst degradation were seen.

Methyl mercury, mercuric chloride, and silver lactate decrease superoxide anion formation and chemotaxis in human polymorphonuclear leucocytes

Cytotoxic effects of mercuric chloride, methyl mercury, and silver lactate on polymorphonuclear leucocytes have been examined by assaying superoxide anion formation capability and chemotaxis of metal-exposed cells. Both superoxide anion formation and chemotaxis were negatively affected by all three metal compounds. Both bacteriotoxic functions were affected in a dose-dependent fashion, the functional deficits were seen at doses not affecting cell viability. Dose-response curves were remarkably similar for all three compounds. The bacteriotoxic capacity of polymorphonuclear leucocytes may be hampered by mercury and silver.

The von Kossa reaction for calcium deposits: silver lactate staining increases sensitivity and reduces background

The classical von Kossa method has been modified: the high silver nitrate concentration in the original was replaced by 0.05% silver lactate with hydroquinone remaining the reducing agent of choice. The present modification stained calcification nodules with a sensitivity comparable to the original von Kossa reaction, but resulted in a reduced background staining in cultured osteoblasts. The method works well also with plastic- or paraffin-embedded tissue sections.

Comparison of the interaction of methyl mercury and mercuric chloride with murine macrophages

The toxicity of organic methyl mercury was studied on murine macrophages in cell culture and compared to that of inorganic mercuric chloride. Long-term treatment of macrophage cultures with methyl mercury resulted in decreased cell viability in a concentration-dependent fashion. Experiments showed that 20 microM methyl mercury was highly toxic, causing cell death within a few days, while cultures exposed to lower levels were less severely affected. Comparison of the toxicity of organic and inorganic mercury by cell viability showed no difference between equimolar concentrations of methyl mercury and mercuric chloride. Furthermore, protein synthesis (interferon-alpha/beta) was reduced in a concentration dependent manner and had the same reduced magnitude in cells treated with either methyl mercury or mercuric chloride. However, impairment of random migration and phagocytosis of macrophages appeared at lower concentrations in cells exposed to methyl mercury than in cells exposed to mercuric chloride. Electron microscopy of cells exposed to methyl mercury revealed mercury deposits in lysosomes and dispersed in the cytoplasm and nuclei. The present study shows that methyl mercury and mercuric chloride impair cell viability and protein production in cell cultures at equimolar concentrations, while methyl mercury inhibits macrophage functions such as migration and phagocytosis at lower concentrations than mercuric chloride.

Distribution of hydroxylated vitamin D metabolites [25OHD3 and 1,25(OH)2D3] in domestic pigs: evidence that 1,25(OH)2D3 is stored outside the blood circulation?

1. The distribution of 25-hydroxycholecalciferol (25OHD3) and 1,25-dihydroxycholecalciferol [1,25(OH)2D3] in various organs from domestic pigs was examined by HPLC. 2. Plasma levels of both metabolites corresponded to those found in healthy human subjects. 3. Tissue concentrations of 25OHD3 in fat, kidney, liver, and intestinal mucosa were low (< 1/3 of plasma levels), whereas tissue concentrations of 1,25(OH)2D3 exceeded plasma levels by factors 3-7, adipose tissue concentrations being the highest. 4. Substantial amounts of activated vitamin D are stored outside the blood-streams and may actively participate in vitamin D and calcium homeostasis.

Late postnatal growth in the dentate area of the rat hippocampus compensates for volumetric changes caused by early postnatal toluene exposure

The present report assesses the reversibility of previously described quantitative morphological alterations in the dentate area of the hippocampi of rats exposed to 500 ppm toluene for 12 h daily from postnatal day 1 (P1) to P28. Following the exposure, rats were allowed to survive until P120. The volumes of hippocampal components, as they appear in Timm-stained histological sections, were determined using the Cavalieri estimator. At P120, no differences were apparent in the volumes of the dentate components of control and experimental animals. The differences observed immediately after exposure were eliminated by significantly larger increases in the sizes of early affected components in experimental animals. Different periods of neurogenesis in rodents and primates are briefly discussed as possible confounders of rodent models of permanent toluene-induced morphological alterations in primates.

Ultrastructure of human osteoblasts and associated matrix in culture

The ultrastructure, as visualized by transmission electron microscopy, of cells obtained from human bone explants and subsequently cultured is described along with the electron microscopic appearance of the associated intercellular matrix. The cells were characterized as osteoblasts on the basis of immunohistochemical, enzymatic, and functional criteria. Although the osteoblasts could be cultured in standard culture media and always appeared singly, not forming syncytia, the cultures were eventually confluent and formed multilayers. The cells were fusiform or cuboidal with diameters ranging between 10-15 microns. The cytoplasm was characterized by numerous large mitochondria, and especially by a very prominent RER. The intercellular matrix was woven with collagen fibres surrounding large numbers of matrix vesicles. In areas with matrix vesicles, evidence for osteoblast activity, i.e. mineralization related to matrix vesicles, could be observed after incubation with beta-glycerophosphate. In conclusion, we provide evidence that human osteoblasts cultured in vitro synthesize collagen and produce a matrix with vesicles capable of initiating mineralization processes.

Lipid peroxidation in early experimental diabetes in rats: effects of diabetes and insulin

The degree of lipid peroxidation was measured in organs from diabetic rats receiving no treatment, and in those from insulin-treated diabetic rats and controls. Lipid peroxidation was measured as organ content of malondialdehyde, a degradation product of polyunsaturated fatty acids. In the kidney, lipid peroxidation was increased after one week of diabetes; insulin treatment reduced the level of lipid peroxidation to levels lower than seen in controls. In the liver, diabetes caused an increased lipid peroxidation, which could be reversed by insulin; no additional effect of insulin was found. In heart and pancreas no effects of diabetes or insulin were demonstrated. The present paper provides evidence that lipid peroxidation is increased in the early stages of experimental diabetes and is reversible by insulin treatment. Hyperinsulinaemia may, in itself, counteract lipid peroxidation in kidney.