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A genetic bottleneck explains the marked changes in mitochondrial DNA (mtDNA) heteroplasmy that are observed during the transmission of pathogenic mutations, but the precise timing of these changes remains controversial, and it is not clear whether selection has a role. These issues are important for the genetic counseling of prospective mothers and for the development of treatments aimed at disease prevention. By studying mice transmitting a heteroplasmic single-base-pair deletion in the mitochondrial tRNA(Met) gene, we show that the extent of mammalian mtDNA heteroplasmy is principally determined prenatally within the developing female germline. Although we saw no evidence of mtDNA selection prenatally, skewed heteroplasmy levels were observed in the offspring of the next generation, consistent with purifying selection. High percentages of mtDNA genomes with the tRNA(Met) mutation were linked to a compensatory increase in overall mitochondrial RNA levels, ameliorating the biochemical phenotype and explaining why fecundity is not compromised.

Somatic mutations of mtDNA are implicated in the aging process, but there is no universally accepted method for their accurate quantification. We have used ultra-deep sequencing to study genome-wide mtDNA mutation load in the liver of normally- and prematurely-aging mice. Mice that are homozygous for an allele expressing a proof-reading-deficient mtDNA polymerase (mtDNA mutator mice) have 10-times-higher point mutation loads than their wildtype siblings. In addition, the mtDNA mutator mice have increased levels of a truncated linear mtDNA molecule, resulting in decreased sequence coverage in the deleted region. In contrast, circular mtDNA molecules with large deletions occur at extremely low frequencies in mtDNA mutator mice and can therefore not drive the premature aging phenotype. Sequence analysis shows that the main proportion of the mutation load in heterozygous mtDNA mutator mice and their wildtype siblings is inherited from their heterozygous mothers consistent with germline transmission. We found no increase in levels of point mutations or deletions in wildtype C57Bl/6N mice with increasing age, thus questioning the causative role of these changes in aging. In addition, there was no increased frequency of transversion mutations with time in any of the studied genotypes, arguing against oxidative damage as a major cause of mtDNA mutations. Our results from studies of mice thus indicate that most somatic mtDNA mutations occur as replication errors during development and do not result from damage accumulation in adult life., Competing Interests: The authors have declared that no competing interests exist.

Plasmin has been proposed to be an important mediator during inflammation/infection. In this study, by using mice lacking genes for plasminogen, tissue-type plasminogen activator (tPA), and urokinase-type PA (uPA), we have investigated the functional roles of active plasmin in infection and sepsis. Two models were used: an infection model by intravenous injection of 1×10⁷ CFU of S. aureus, and a sepsis model by intravenous injection of 1.6×10⁸ CFU of S. aureus. We found that in the infection model, wild-type (WT) mice showed significantly higher survival rates than plasminogen-deficient (plg⁻/⁻) mice. However, in the sepsis model, plg⁻/⁻ or tPA⁻/⁻/uPA⁻/⁻ mice showed the highest survival rate whereas WT and tPA⁺/⁻/uPA⁺/⁻ mice showed the lowest survival rate, and plg⁺/⁻, tPA⁻/⁻, and uPA⁻/⁻ mice had an intermediate survival rate. These results indicate that the levels of active plasmin are critical in determining the survival rate in the sepsis, partly through high levels of inflammatory cytokines and enhanced STAT3 activation. We conclude that plasmin is beneficial in infection but promotes the production of inflammatory cytokines in sepsis that may cause tissue destruction, diminished neutrophil function, and an impaired capacity to kill bacteria which eventually causes death of these mice.

Aims: In experimental studies parathyroid hormone (PTH) has been associated with underlying causes of heart failure (HF) such as atherosclerosis, left ventricular hypertrophy, and myocardial fibrosis. Individuals with increased levels of PTH, such as primary or secondary hyperparathyroidism patients, have increased risk of ischaemic heart disease and HF. Moreover, increasing PTH is associated with worse prognosis in patients with overt HF. However, the association between PTH and the development HF in the community has not been reported., Methods and Results: In a prospective, community-based study of 864 elderly men without HF or valvular disease at baseline (mean age 71 years, the ULSAM study) the association between plasma (P)-PTH and HF hospitalization was investigated adjusted for established HF risk factors (myocardial infarction, hypertension, diabetes, electrocardiographic left ventricular hypertrophy, smoking, and hypercholesterolaemia) and variables reflecting mineral metabolism (S-calcium, S-phosphate, P-vitamin D, S-albumin, dietary calcium and vitamin D intake, physical activity, glomerular filtration rate, and blood draw season). During follow-up (median 8 years), 75 individuals were hospitalized due to HF. In multivariable Cox-regression analyses, higher P-PTH was associated with increased HF hospitalization (hazard ratio for 1-SD increase of PTH, 1.41, 95% CI 1.12-1.77, P = 0.003). Parathyroid hormone also predicted hospitalization in participants without apparent ischaemic HF and in participants with normal P-PTH., Conclusion: In a large community-based sample of elderly men, PTH predicted HF hospitalizations, also after accounting for established risk factors and mineral metabolism variables.  Our data suggest a role for PTH in the development of HF even in the absence of overt hyperparathyroidism.

Context: Blood levels of 25-hydroxyvitamin D [25(OH)D] is the generally accepted indicator of vitamin D status, but no universal reference level has been reached., Objective: The objective of the study was to determine the threshold at which low plasma 25(OH)D levels are associated with fractures in elderly men and clarify the importance of low levels on total fracture burden., Design and Participants: In the Uppsala Longitudinal Study of Adult Men, a population-based cohort (mean age, 71 yr, n = 1194), we examined the relationship between 25(OH)D and risk for fracture. Plasma 25(OH)D levels were measured with high-pressure liquid chromatography-mass spectrometry., Setting: The study was conducted in the municipality of Uppsala in Sweden, a country with a high fracture incidence., Main Outcome Measure: Time to fracture was measured., Results: During follow-up (median 11 yr), 309 of the participants (26%) sustained a fracture. 25(OH)D levels below 40 nmol/liter, which corresponded to the fifth percentile of 25(OH)D, were associated with a modestly increased risk for fracture, multivariable-adjusted hazard ratio 1.65 (95% confidence interval 1.09-2.49). No risk difference was detected above this level. Approximately 3% of the fractures were attributable to low 25(OH)D levels in this population., Conclusions: Vitamin D insufficiency is not a major cause of fractures in community-dwelling elderly men in Sweden. Despite the fact that cutaneous synthesis of previtamin D during the winter season is undetectable at this northern latitude of 60 degrees, only one in 20 had 25(OH)D levels below 40 nmol/liter, the threshold at which the risk for fracture started to increase. Genetic adaptations to limited UV light may be an explanation for our findings.

Objective: Hyperphosphatemia is a cardiovascular risk factor in patients with chronic kidney disease. Relations of circulating calcium (Ca) and phosphorus (Pi) to long-term mortality risk in the community require further investigation., Methods and Results: Associations of serum Ca and Pi to mortality were evaluated in a community-based cohort of 2176 men (mean age, 50.1 years). During follow-up (median, 29.8 years), 1009 men died, and 466 of these deaths resulted from cardiovascular causes. In Cox proportional hazards models, serum Pi and [CaxPi] were independent predictors of total mortality (hazard ratio per SD, 1.06; 95% CI, 1.01-1.12; P=0.03; 1.07; 95% CI, 1.01-1.12; P=0.01) and cardiovascular mortality (1.10; 95% CI, 1.02-1.18; P=0.01; 1.10; 95% CI, 1.03-1.19; P=0.008). Serum Ca was associated with risk of total mortality (1.08; 95% CI, 1.01-1.16; P=0.02) and noncardiovascular mortality (1.10; 95% CI, 1.01-1.21; P=0.04). Results were consistent after multivariate adjustments in subsamples of individuals with estimated glomerular filtration rate >90 mL/min and low-to-normal serum Ca and Pi., Conclusions: Circulating Ca and Pi levels are associated with risks of total, cardiovascular, and noncardiovascular mortality in the community, and their conjoint effects are additive. Additional studies are warranted to evaluate whether Ca and Pi are modifiable risk factors in the general population.

Context: In recent years, an association has been noted between several abnormalities that characterize the metabolic syndrome (MetS) and primary hyperparathyroidism (pHPT). These abnormalities include dyslipidaemia, obesity, insulin resistance and hypertension. The correlations between plasma calcium, parathyroid hormone (PTH) and the variables in the MetS in a normal population are still unclear., Objective: To describe correlations between plasma calcium and PTH and the various abnormalities present in the MetS in a healthy population., Design: We studied 1016 healthy individuals from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) population of 70 years old, by means of plasma analyses of calcium, PTH, creatinine, lipids, insulin and glucose, as well as by standardized blood pressure measurements. Further, body mass index (BMI) and waist circumference were determined., Results: The more National Cholesterol Education Program (NCEP) criteria for the MetS that were met, the higher the s-PTH and albumin-corrected s-calcium. Further, positive correlations between plasma calcium and BMI (P = 0.0003), waist circumference (P = 0.0009) and insulin resistance (P = 0.079) were found. PTH and BMI (P < 0.0001), waist circumference (P < 0.0001), systolic blood pressure (P = 0.0034), diastolic blood pressure (P = 0.0008), serum triglycerides (P = 0.0003) and insulin resistance (P = 0.0003) were positively correlated, whereas serum high density lipoproteins (HDL) (P = 0.036) and PTH were negatively correlated., Conclusions: We conclude that PTH correlates with several of the metabolic factors included in the MetS within a normocalcaemic population. In addition, individuals with mild pHPT present significantly more NCEP criteria for MetS. We postulate that increased levels of PTH in pHPT may be associated with the increased cardiovascular morbidity and mortality seen in pHPT.

Objective: To assess the functional roles of plasmin in a murine model of Staphylococcus aureus-induced bacterial arthritis., Methods: Bacterial arthritis was induced in plasminogen-deficient (Plg(-/-)) and wild-type (Plg(+/+)) littermates by local injection of 1 x 10(6) colony-forming units of S aureus into the knee joints. Human plasminogen was administered to Plg(-/-) mice on days 0-7 or days 7-14. Antibiotic treatment was administered to Plg(-/-) mice on days 7-14. Bacteria counts and histologic, immunohistochemical, and Western blot analyses were performed., Results: In Plg(+/+) mice, S aureus counts had declined within 2 days, and by day 28 the bacteria had been completely eliminated. However, S aureus was still detectable in all injected joints from Plg(-/-) mice, and bacteria counts were 27 times higher than the amount injected on day 0. The extent of macrophage and neutrophil recruitment to the infected joints was comparable for Plg(+/+) and Plg(-/-) mice on days 1, 7, and 14. The activation of these inflammatory cells appeared to be impaired in Plg(-/-) mice, however. Treatment of Plg(-/-) mice with antibiotic (cloxacillin) resulted in successful killing of the bacteria, but the necrotic tissue remained in the infected joints. When human plasminogen was given intravenously to Plg(-/-) mice daily for 7 days, bacterial clearance was greatly improved as compared with their untreated counterparts, and the amount of necrotic tissue in the joint cavity was dramatically reduced. The expression of interleukin 6 (IL-6) and IL-10 was higher in Plg(+/+) mice than in Plg(-/-) mice during bacterial arthritis., Conclusion: Our findings indicate that plasmin plays a pluripotent role in protecting against S aureus-induced arthritis by activating inflammatory cells, killing bacteria, removing necrotic tissue, and enhancing cytokine expression.

Objective: Dyslipidemia, hypertension, diabetes mellitus and also primary hyperparathyroidism (pHPT) are associated with an increased risk of cardiovascular diseases. Metabolic abnormalities in mild pHPT have been reported, but never in cases with normal calcium and high parathyroid hormone (PTH) levels, i.e. suffering from 'normocalcemic pHPT'. Our aim was to explore the occurrence of these metabolic abnormalities in individuals with normocalcemic pHPT identified in a population-based screening, and the effects of parathyroidectomy vs conservative treatment on metabolic variables., Design and Methods: A population-based screening of 5202 post-menopausal women identified 30 patients with normal calcium, inappropriately high PTH and normal creatinine. A 5-year follow-up included 15 parathyroidectomized (PTx) and nine conservatively followed cases, in a non-randomized setting, together with age-matched controls. Biochemical variables and body mass index (BMI) were investigated., Results: At study entry, cases had higher calcium, PTH, glucose, low-density lipoprotein (LDL)/high-density lipoprotein (HDL)-cholesterol, very low-density lipoprotein (VLDL)-cholesterol, total triglycerides, and BMI compared to controls (P = < 0.0001-0.035). The cases had a lower HDL-cholesterol value (P = 0.013) and one third of the cases had hypertriglyceridemia. During follow-up, the PTx cases decreased in calcium, PTH, LDL/HDL-cholesterol, total and LDL-cholesterol (P = 0.0076-0.022). Investigated biochemical variables remained adverse in conservatively followed cases during follow-up except a decreased LDL-cholesterol value. All surgically treated patients had parathyroid adenoma., Conclusions: Cases with normocalcemic pHPT have increased proatherogenic lipoprotein levels, BMI and glucose levels compared to age-matched controls. Parathyroidectomy has positive effects on some of these variables and reverses them to the same level as the controls, while conservative treatment fails to normalize the investigated metabolic variables.

Objective: Postmenopausal women are at increased risk of primary hyperparathyroidism (pHPT). Secondary dyslipidaemia in pHPT has attracted little attention, although morbidity and mortality associated with cardiovascular diseases have been reported to be increased in these patients., Design: A population-based screening programme was used to recruit postmenopausal women with mild, asymptomatic pHPT (mean serum calcium 2.57 +/- 0.12 mmol/l) and matched controls. MEASUREMENTS AND PATIENTS: Serum lipids, lipoprotein fractions and influences of treatment for the parathyroid disease were studied in 87 case-control pairs (mean age 67 years), 69 of whom completed a 5-year follow-up period., Results: pHPT was characterized by decreased serum high-density lipoprotein (HDL)-cholesterol, increased total triglycerides, very-low-density lipoprotein (VLDL)-triglycerides and VLDL-cholesterol levels and an elevated atherogenic index. The differences were more pronounced in the cases with serum parathyroid hormone levels in the normal range and were inversely correlated to the serum parathyroid hormone level. Parathyroidectomy, with or without additive hormone replacement therapy, normalized the dyslipidaemia. Five-year surveillance of pHPT without treatment was associated with a maintained increase in total triglycerides and the atherogenic index and a decrease in HDL-cholesterol levels., Conclusion: Proatherosclerotic dyslipidaemia characterizes mild pHPT and is effectively reversed by parathyroidectomy. As dyslipidaemia might contribute to the increased risk of cardiovascular diseases and death observed in pHPT, the findings favour operative intervention rather than conservative surveillance in mild, asymptomatic pHPT in postmenopausal females.

The in vivo kinetics of lactate and pyruvate in the extracellular space of subcutaneous adipose tissue after glucose ingestion were investigated in healthy volunteers by the use of a microdialysis sampling technique. Comparison was made with the metabolite levels in venous plasma. The absolute subcutaneous tissue concentrations of lactate and pyruvate were estimated in the fasting state by perfusion with varying lactate- and pyruvate-containing solutions. An equilibrium with the surrounding extracellular fluid was found for both lactate and pyruvate in concentrations similar to those in venous plasma. After glucose ingestion there was an increase in the circulating levels of glucose, lactate, and pyruvate, which returned to base-line values within 3 h. There was a more marked increase in lactate in subcutaneous adipose tissue than in venous blood, and the adipose tissue lactate remained elevated for at least 3 h. In contrast, pyruvate levels increased much less in subcutaneous fat than in venous blood. The addition of isoproterenol (which inhibits adipose tissue glucose metabolism) to the tissue perfusate lowered the subcutaneous tissue lactate levels significantly but did not affect the subcutaneous pyruvate levels. These data suggest that human subcutaneous adipose tissue is a source of in vivo lactate production after glucose ingestion. Since lactate is thought to be a major substrate for glycogen synthesis in the liver, the present findings may provide evidence of a new and important role of the adipose tissue metabolism in the regulation of whole body glucose homeostasis in humans.