Dynamical Systems Gradient method for solving nonlinear equations with monotone operators

A version of the Dynamical Systems Gradient Method for solving ill-posed nonlinear monotone operator equations is studied in this paper. A discrepancy principle is proposed and justified. A numerical experiment was carried out with the new stopping rule. Numerical experiments show that the proposed stopping rule is efficient. Equations with monotone operators are of interest in many applications.Comment: 2 figure

Utility of serum biomarker indices for staging of hepatic fibrosis before and after venesection in patients with hemochromatosis caused by variants in HFE

Background & Aims Hemochromatosis that is associated with variants in the homeostatic iron regulator gene (HFE) is characterized by intestinal absorption of iron and excessive body and hepatic iron stores; it can lead to hepatic fibrosis and cirrhosis. Fibrosis has been staged by analysis of liver biopsies, but non-invasive staging methods are available. We evaluated the ability of aspartate aminotransferase:platelet ratio index (APRI), the fibrosis-4 (FIB-4) index, and gamma-glutamyl transferase:platelet ratio (GPR) to assess hepatic fibrosis staging in subjects with HFE-associated hemochromatosis, using liver biopsy-staged fibrosis as the reference standard. Methods We performed a retrospective, cross-sectional analysis of 181 subjects with HFE-associated hemochromatosis and hepatic fibrosis staged by biopsy analysis and available serum samples. We calculated APRI, FIB-4, and GPR at diagnosis for all 181 subjects and following venesection therapy in 64 of these subjects (7 subjects had follow-up biopsy analysis). We used area under the receiver operating characteristic curve (AUROC) analysis to assess the relationships between APRI score, FIB-4 score, and GPR and advanced (F3–F4) fibrosis and to select cut-off values. Results Hepatic fibrosis stage correlated with APRI score (r = 0.54; P \u3c .0001), FIB-4 score (r = 0.35; P \u3c .0001), and GPR (r = 0.36, P \u3c .0001). An APRI score above 0.44 identified patients with advanced fibrosis with an AUROC of 0.88, 79.4% sensitivity, 79.4% specificity, and 81% accuracy. A FIB-4 score above 1.1 identified patients with advanced fibrosis with an AUROC of 0.86, 80% sensitivity, 80.3% specificity, and 81% accuracy. A GPR above 0.27 identified patients with advanced fibrosis with an AUROC of 0.76, 67.7% sensitivity, 70.3% specificity, and 69% accuracy. APRI score was significantly more accurate than GPR (P = .05) in detecting advanced fibrosis; there was no difference between APRI and FIB-4. Venesection treatment was associated with significant reductions in APRI (P \u3c .0001) and GPR (P\u3c .001), paralleling fibrosis regression observed in available liver biopsies. Post-venesection APRI identified 87% of subjects with advanced fibrosis that decreased to levels that indicate stage F1–F2 fibrosis. Conclusions In a retrospective study of 181 subjects with HFE-associated hemochromatosis, we found that APRI and FIB-4 scores identified patients with advanced hepatic fibrosis with 81% accuracy. APRI scores might also be used to monitor fibrosis regression following venesection

Utility of hepatic or total body iron burden in the assessment of advanced hepatic fibrosis in HFE hemochromatosis

Development of advanced hepatic fibrosis in HFE Hemochromatosis (HH) is influenced by hepatic iron concentration (HIC) and age. In patients with HH, it is important to assess the likelihood of cirrhosis and thus the need for confirmatory liver biopsy. Therapeutic phlebotomy also provides an estimate of mobilisable iron stores. We determined whether mobilisable iron stores may predict the presence of advanced fibrosis. Retrospective analysis of 137 male and 65 female HH subjects was undertaken. Biochemical, histological and phlebotomy data were available on all subjects. The mean values of HIC, HIC × [age], mobilisable iron, mobilisable iron × [age] and serum ferritin in the cohort were higher in the group with advanced fibrosis. HIC had an optimum sensitivity and specificity of 73% for the diagnosis of advanced liver fibrosis, with a cut-off HIC level of 200 µmol/g (AUROC 0.83, p \u3c 0.0001). AUROC for HIC was greater in females (0.93) than males (0.79). Mobilisable iron had an optimum sensitivity and specificity both of 83% at a cut-off of 9.6 g for the prediction of advanced fibrosis in all subjects (AUROC 0.92, p \u3c 0.0001). Mobilisable iron stores provide a simple, clinically useful indication of the risk of advanced fibrosis and should routinely be considered

A Comparison of Sound Levels in Open Plan Versus Pods in a Neonatal Intensive Care Unit

Author version made available in accordance with publisher copyright policy.OBJECTIVE: The objective of this study was to compare the noise levels recorded in two different neonatal intensive care unit (NICU) settings: a pod and an open plan NICU located in the same hospital. BACKGROUND: The NICU is a busy environment with ambient noise levels that often exceed established recommendations. This noise deleteriously affects the physiological stability and developmental outcomes of sick and preterm infants. Pods have reduced numbers of cots (in this case, 6) compared to open plan NICUs (in this case, 11), yet the noise levels in pods have not been reported. METHOD: This study compared real-time decibel (dB) levels in an A-weighted scale, captured continuously by sound dosimeters mounted in both NICU settings for a period of 4 weeks: a pod setting and an open plan NICU. Researchers also collected observational data. RESULTS: The average noise level recorded in the pod was 3 dBs less than in the open plan NICU. This result was statistically significant. However, dB recordings in both areas were over the recommended limits by 4-6 dBs, with isolated peaks between 74.5 dBs (NICU) and 75.9 dBs (pod). Observational data confirmed this correlation. CONCLUSIONS: Further research to evaluate interventions to decrease the noise levels in both settings are needed, especially during times of peak activity. Staff working in these settings need to be more aware that control of acoustic levels is important in the neuroprotection of neonates. Coupling this with careful consideration to structural components and evidence-based design planning may contribute to lowering dB levels in the NICU environment

Detection of HFE haemochromatosis in the clinic and community using standard erythrocyte tests

Detection of HFE Haemochromatosis (HH) is challenging in the absence of clinical features. HH subjects have elevated erythrocyte parameters compared to those without HH, but it remains unclear how this could be applied in clinical practice. Thus, we determined the sensitivity, specificity and clinical utility of erythrocyte parameters in 144 HH subjects with (n = 122) or without (n = 22) clinical and/or biochemical expression of iron overload, 1844 general population controls, and 700 chronic disease subjects. For both expressing and non-expressing HH subjects, the mean pre- and post-phlebotomy values of mean cell volume (MCV) and mean cell haemoglobin (MCH) were always significantly higher when compared to all other groups and demonstrated excellent diagnostic utility for detection of HH in men and women (AUROC 0.83-0.9; maximal sensitivity and specificity 82% and 78%) using cut-off values for MCV \u3e91 fL or MCH \u3e31 pg, respectively. Between 34 and 62% of all HH subjects would be detected, and94 fL or 32.2 pg, respectively, were evaluated

Detection of HFE haemochromatosis in the clinic and community using standard erythrocyte tests

Detection of HFE Haemochromatosis (HH) is challenging in the absence of clinical features. HH subjects have elevated erythrocyte parameters compared to those without HH, but it remains unclear how this could be applied in clinical practice. Thus, we determined the sensitivity, specificity and clinical utility of erythrocyte parameters in 144 HH subjects with (n = 122) or without (n = 22) clinical and/or biochemical expression of iron overload, 1844 general population controls, and 700 chronic disease subjects. For both expressing and non-expressing HH subjects, the mean pre- and post-phlebotomy values of mean cell volume (MCV) and mean cell haemoglobin (MCH) were always significantly higher when compared to all other groups and demonstrated excellent diagnostic utility for detection of HH in men and women (AUROC 0.83-0.9; maximal sensitivity and specificity 82% and 78%) using cut-off values for MCV \u3e91 fL or MCH \u3e31 pg, respectively. Between 34 and 62% of all HH subjects would be detected, and94 fL or 32.2 pg, respectively, were evaluated

Cellular plasticity in liver regeneration - spotlight on cholangiocytes

The liver\u27s remarkable capacity to self‐repair and regenerate following tissue injury has been recognized since the ancient Greek myth of Prometheus. However, the diverse potential sources of this regenerative capacity have been an area of hot debate, and only recently have studies started to unravel the actual degree of hepatic cell plasticity. Deng et al. established through lineage tracing experiments using a double‐fluorescent reporter system that biliary epithelial cells significantly contributed to hepatocyte regeneration in two murine chronic liver injury models. Furthermore, during the cholangiocyte‐to‐hepatocyte conversion, biphenotypic cells were identified in both mouse models and human cirrhotic livers. Following analysis of liver progenitor cell markers and mature cholangiocytes, the authors concluded that cholangiocytes directly lineage‐converted to hepatocytes without a progenitor cell intermediate and suggested these biphenotypic cells as potential cellular sources for future therapeutic transplantation strategies

Clinical practice guidelines on hemochromatosis: Asian Pacific Association for the Study of the Liver

Hereditary hemochromatosis is the result of pathogenic variants in multiple genes that can result in increased body iron stores with excess iron deposited in various organs, including the liver, pancreas, and heart. The two most important advances in the field over the past 30 years have been the identification of the HFE gene (and the associated p.Cys282Tyr substitution), and the discovery of the hormone hepcidin, which is inappropriately low in this condition and is the pathophysiological basis of the increased iron absorption. The identification of mutations in the HFE gene and subsequent studies have reshaped diagnostic algorithms resulting in a marked reduction in the need for liver biopsy. The discovery of hepcidin has resulted in many studies that have dramatically improved our understanding of iron metabolism with clear potential therapeutic implications. The variable clinical expression of hemochromatosis has puzzled clinicians and scientists, and our understanding of the factors that influence the phenotype has increased over recent years. Nevertheless, increased clinician and patient awareness, early diagnosis, and therapeutic phlebotomy to restore normal life expectancy are still the cornerstones of management. The classic triad of cirrhosis, diabetes, and skin pigmentation is now uncommon, and many patients are diagnosed with minimal or no symptoms

Utility and limitations of hepascore and transient elastography to detect advanced hepatic fibrosis in HFE hemochromatosis

Aspartate aminotransferase-to-platelet ratio index (APRI) and Fibrosis-4 Index (Fib4) have been validated against liver biopsy for detecting advanced hepatic fibrosis in HFE hemochromatosis. We determined the diagnostic utility for advanced hepatic fibrosis of Hepascore and transient elastography compared with APRI and Fib4 in 134 newly diagnosed HFE hemochromatosis subjects with serum ferritin levels \u3e 300 µg/L using area under the receiver operator characteristic curve (AUROC) analysis and APRI- ( \u3e 0.44) or Fib4- ( \u3e 1.1) cut-offs for AHF, or a combination of both. Compared with APRI, Hepascore demonstrated an AUROC for advanced fibrosis of 0.69 (95% CI 0.56–0.83; sensitivity = 69%, specificity = 65%; P = 0.01) at a cut-off of 0.22. Using a combination of APRI and Fib4, the AUROC for Hepascore for advanced fibrosis was 0.70 (95% CI 0.54–0.86, P = 0.02). Hepascore was not diagnostic for detection of advanced fibrosis using the Fib4 cut-off. Elastography was not diagnostic using either APRI or Fib4 cut-offs. Hepascore and elastography detected significantly fewer true positive or true negative cases of advanced fibrosis compared with APRI and Fib4, except in subjects with serum ferritin levels \u3e 1000 µg/L. In comparison with APRI or Fib4, Hepascore or elastography may underdiagnose advanced fibrosis in HFE Hemochromatosis, except in individuals with serum ferritin levels \u3e 1000 µg/L

Sperm competition-induced plasticity in the speed of spermatogenesis

Background: Sperm competition between rival ejaculates over the fertilization of ova typically selects for the production of large numbers of sperm. An obvious way to increase sperm production is to increase testis size, and most empirical work has focussed on this parameter. Adaptive plasticity in sperm production rate could also arise due to variation in the speed with which each spermatozoon is produced, but whether animals can respond to relevant environmental conditions by modulating the kinetics of spermatogenesis in this way has not been experimentally investigated. Results: Here we demonstrate that the simultaneously hermaphroditic flatworm Macrostomum lignano exhibits substantial plasticity in the speed of spermatogenesis, depending on the social context: worms raised under higher levels of sperm competition produce sperm faster. Conclusions: Our findings overturn the prevailing view that the speed of spermatogenesis is a static property of a genotype, and demonstrate the profound impact that social environmental conditions can exert upon a key developmental process. We thus identify, to our knowledge, a novel mechanism through which sperm production rate is maximised under sperm competition