Genome-wide functional annotation of dual-specificity protein- and lipid-binding modules that regulate protein interactions.

Emerging evidence indicates that membrane lipids regulate protein networking by directly interacting with protein-interaction domains (PIDs). As a pilot study to identify and functionally annodate lipid-binding PIDs on a genomic scale, we performed experimental and computational studies of PDZ domains. Characterization of 70 PDZ domains showed that ~40% had submicromolar membrane affinity. Using a computational model built from these data, we predicted the membrane-binding properties of 2,000 PDZ domains from 20 species. The accuracy of the prediction was experimentally validated for 26 PDZ domains. We also subdivided lipid-binding PDZ domains into three classes based on the interplay between membrane- and protein-binding sites. For different classes of PDZ domains, lipid binding regulates their protein interactions by different mechanisms. Functional studies of a PDZ domain protein, rhophilin 2, suggest that all classes of lipid-binding PDZ domains serve as genuine dual-specificity modules regulating protein interactions at the membrane under physiological conditions.

Strategy and Efficacy of Generic and Pan-genotypic Sofosbuvir/Velpatasvir in Chronic Hepatitis C Virus: A Myanmar Experience.

BACKGROUND: In resource-constrained areas, generic direct-acting antivirals (DAAs) have considerably reduced the cost of hepatitis C virus (HCV) therapy while there remain significant costs related to the baseline and follow-up virologic assays. AIM: The aim was to assess the efficacy and safety of HCV therapy in Myanmar with pan-genotypic generic DAA sofosbuvir/velpatasvir (SOF/VEL) and with and without the baseline genotype testing, while the duration of treatment and use of ribavirin (RBV) was dictated by cirrhosis and prior treatment failure. METHODS: Between September 2016 and June 2017, data from the 359 participants who completed treatment with SOF/VEL (± RBV) for 12-24 weeks were analyzed. Two hundred one patients did not have the baseline HCV genotype tested. RESULTS: Regimens included SOF/VEL for 12 weeks (n = 43), SOF/VEL/RBV for 12 weeks (n = 275), or SOF/VEL/RBV for 24 weeks (n = 41). The mean age was 52 years, 44% were men (n = 159), 41 (11.4%) had a history of previous DAA therapy, 7 (1.9%) had a history of hepatocellular carcinoma, and 55 (15.3%) had cirrhosis. Overall, the sustained viral response (SVR)12 rate was 98.6% (354/359) and with a good adverse event profile. SVR rates were similar to those with and without baseline genotype testing and also across all genotypes in those who had genotype tested. CONCLUSIONS: In Myanmar, generic and pan-genotypic SOF/VEL ± RBV is a highly effective and safe treatment for HCV, regardless of the HCV genotype, and therefore, the requirement for the baseline genotype can be eliminated. Future strategies should include elimination of treatment and end of treatment HCV RNA testing to enhance treatment uptake and further reduce cost.

Bacterial mechanosensitive channels: integrating physiology, structure and function.

When confronted with hypo-osmotic stress, many bacterial species are able rapidly to adapt to the increase in cell turgor pressure by jettisoning cytoplasmic solutes into the medium through membrane-tension-gated channels. Physiological studies have confirmed the importance of these channels in osmoregulation. Mutagenesis of one of these channels, combined with structural information derived from X-ray crystallography, has given the first clues of how a mechanosensitive channel senses and responds to membrane tension.

Energy requirements of a postobese man reporting a low energy intake at weight maintenance.

Three experiments were performed to test the validity of the low reported energy intake of weight maintenance in a postobese man. In the first experiment the subject reported a mean energy intake of 8008 kJ/d during 16 d and he maintained a stable body weight. This finding was not reproduced in the second experiment, which consisted of a 6-d inpatient study during which the subject was confined to a whole-body calorimeter for 5 d. Indeed, he lost weight when fed a controlled energy intake of 7950 kJ/d. Moreover, this experiment showed that direct and indirect calorimetry provided comparable energy-expenditure measurements during this period. Finally, when the subject was refed a controlled energy intake of 7950 kJ/d for 21 d, body weight and fat losses were observed. Therefore, these observations do not support the validity of the low energy intake that may be reported by people predisposed to obesity.

Repeatability of 24-h energy expenditure measurements in humans by indirect calorimetry.

To estimate sources and extent of variation in energy expenditure (EE), as measured by indirect calorimetry in a room-sized human calorimeter, a number of 24-h measurements were compiled. Measured oxygen consumption and carbon dioxide production from alcohol combustion experiments averaged 101.5% of the theoretical value with a coefficient of variation (CV) of 1.4%. Experiment 1 consisted of four men who had the following averages: age, 41 y; height, 179 cm; weight, 84.6 kg; and fat, 23.5%. Five measurements, separated by 1 d, were made on each subject. Daily and basal EE averaged 2852 and 1691 kcal/d, respectively, with a within-subject CV of 2.7% and 2.4%, respectively. Experiment 2 consisted of five men who had the following averages: age, 48 y; height, 181.6 cm; weight, 87 kg; and fat, 23%. Five measurements made on each subject were separated by 1-3 wk. Daily and basal EE averaged 2619 and 1837 kcal/d, respectively, with a within-subject CV of 4.6% and 2.9%, respectively.

How much is too much? Folinic acid rescue dose in children with acute lymphoblastic leukaemia.

The effect of folinic acid rescue dose on the event-free survival of 71 children with acute lymphoblastic leukaemia was examined in a retrospective clinical study. All patients, diagnosed between 1 January 1980 and 1 January 1989, were treated according to the Norwegian Pilot protocol which included eight courses of high dose (6-8 g/m2/24 h intravenous infusion) methotrexate. Following the infusion, a uniform dose of 75 mg (at 36 h after the beginning of the drug infusion) and 15 mg (at 39-106 h) folinic acid rescue was administered to all patients, at predetermined intervals. The uniformity of the rescue dose resulted in distribution of dosages in the range of 38-140 mg/m2 and 7.5-28 mg/m2 for the different periods, respectively, when the dose was recalculated on the basis of the body surface area of the individual patients. The event-free survival of children receiving less or more than 15 mg/m2 (75 mg/m2) rescue dose was compared. Although no significant difference was found, a tendency was observed for a lower risk of relapse in patients receiving less folinic acid. No major methotrexate-related toxicity was observed in the group of patients receiving the lower dose of rescue. These observations suggest that the reduction of folinic acid rescue dose below the generally accepted 12-15 mg/m2 dose may increase the efficacy of high-dose methotrexate therapy while still remaining safe in preventing treatment-related toxicity. Prospective, randomised clinical trials are needed to examine the role of rescue as a determinant of effective exposure to methotrexate in patients receiving high-dose methotrexate treatment.

On the prognostic value of systemic methotrexate clearance in childhood acute lymphocytic leukemia.

The prognostic value of systemic methotrexate clearance (ClMTX) during high-dose therapy was evaluated in a cohort of 42 children with acute lymphocytic leukemia (ALL). As part of an extensive chemotherapy protocol, they had received a total of 293 methotrexate (MTX) infusions in the 6-8 g/m2 dose range. At the termination of the study, when they had all been followed up for 3.5 years or more, 26 of these patients were still in continuous complete remission, whereas 16 had suffered relapse. The intrapatient variability in ClMTX during the eight courses was up to six-fold. In 67% of the patients, the maximum level of ClMTX reached at least twice the minimum value. The coefficients of variation for the intra- and interindividual variability in ClMTX were 9-57% and 26-41%, respectively. The cumulative probability of relapse, estimated by the Kaplan-Meier procedure, was increased for patients with a high ClMTX during the initial treatment course, but the difference was not significant on a 5% level. There was no significant relationship between high individual median ClMTX and subsequent relapse of ALL. However, ClMTX during the initial infusion, the time-dependent mean for ClMTX, and the individual patient's median ClMTX, were significant predictors for event-free survival in a Cox proportional hazards regression analysis. The present study demonstrates gross pharmacokinetic variability and unpredictable values of ClMTX in subsequent courses after standardized administration of MTX to paediatric patients with ALL. In spite of the association between ClMTX and prognosis shown by some of the analyses, estimates of ClMTX rates may not necessarily be related to disease outcome in a way that can be exploited to the benefit of the individual patient.

Variability in methotrexate serum and cerebrospinal fluid pharmacokinetics in children with acute lymphocytic leukemia: relation to assay methodology and physiological variables.

Methotrexate (MTX) steady state concentrations were evaluated in 42 children who had received high-dose infusions (6-8 g/m2) for acute lymphocytic leukemia. Concentrations in serum and cerebrospinal fluid (CSF) measured by immunoassay were found to be highly variable. Reanalysis by a reference high-pressure liquid chromatography method ruled out analytical factors as a source of this variability. The correlation coefficient between the analytical methods was 0.77 for the serum data and 0.88 for the CSF data. The variability of serum and CSF concentrations was higher in younger patients (serum; P = 0.05 and CSF; P = 0.18), and the CSF concentration decreased with decreasing age and in later courses. Body surface area, body mass index, weight, and gender were not significantly related to MTX variability. We conclude that the pronounced pharmacokinetic variability seen during MTX infusions remains largely unexplained.

PharmCalc: program for the calculation of clinical pharmacokinetic parameters of methotrexate.

A new program package (PharmCalc) has been developed for the calculation of basic pharmacokinetic parameters (half-time, systemic clearance, renal clearance, AUC, volume of distribution, CSF/serum distribution ratio) of methotrexate (MTX). The program helps in the early recognition of patients at risk for toxicity and calculates the dosage of folinic acid rescue adjusted to the serum levels of MTX. The program offers a standardized and automated evaluation procedure for MTX pharmacokinetics and provides an easy-to-use tool for further research in this field. The concept and routines of the program are described.

Methotrexate administered by 6-h and 24-h infusion: a pharmacokinetic comparison.

The pharmacokinetics of 8 g/m2 methotrexate (MTX) was compared following short (6 h) and long (24 h) infusions of the drug to 11 children with osteogenic sarcoma (OS; 42 infusion) and 28 children with acute lymphoblastic leukemia (ALL: 118 infusions), respectively. No difference was observed in the first-phase half-life, in systemic clearance or in the volume of distribution of the drug (P greater than 0.05). The concentration of MTX at the end of the infusion was approximately 4-fold higher when the drug was given over only 6 h. However, patients receiving 24-h infusions had approximately 9-fold higher levels by 24 h after the beginning of the infusion. The area under the data curve from start of the MTX infusion until the beginning of folinic acid rescue administration was significantly higher in patients with osteogenic sarcoma (6-h infusions), while the area under the log-data curve was significantly longer in the ALL group (24-h infusions) for the same period. The latter parameter is considered to be characteristic for the concentration-time-effect relationship. The longer duration of MTX administration (with delayed rescue) is thought to be more beneficial from the pharmacokinetic aspect. Patients with osteogenic sarcoma had significantly lower concentrations of MTX at the end of their last treatment with MTX than at the end of the first infusion. Patients developing MTX toxicity had shorter half-lives of MTX in the beta phase. It is suggested that cisplatin induced tubular loss of MTX and folinic acid is responsible for these observations. A wider application of clinical pharmacologic findings in the practice of the administration of cytostatics is indicated.

7-Hydroxymethotrexate concentrations in serum and cerebrospinal fluid of children with acute lymphoblastic leukemia.

Concentrations of methotrexate (MTX) and 7-hydroxymethotrexate (7-OH-MTX) were determined by HPLC in the serum and cerebrospinal fluid (CSF) of 29 children with acute lymphoblastic leukemia. CSF and serum samples were obtained at the end of 104 infusions of MTX given in a dose range of 0.5-8.0 g/m2. Concentrations, distribution ratios in serum and CSF for MTX and 7-OH-MTX, and the metabolic index were analyzed with regard to the MTX dose, age and clinical state of the patients. A wide inter-patient (2- to 12-fold) but narrower (1.1- to 3.5-fold) intra-patient variability of the concentrations was observed. A dose-proportional increase in the metabolite concentration was found in serum. On the other hand, the elevation of the level of metabolite in CSF was less than proportional to the dose. The CSF/serum distribution data suggest the existence of a saturable carrier system for MTX and 7-OH-MTX between serum and CSF that has lower affinity for 7-OH-MTX. No correlation was found between concentrations of MTX and 7-OH-MTX in the serum of patients receiving the same dose of MTX. No significant difference was observed in the values for metabolic index between relapsed patients and those who were in continuous complete remission. A significant correlation was found between age and metabolic index: the younger the patient, the higher the metabolite concentration measured in serum.

Inhibition of brain glutamate decarboxylase by glutarate, glutaconate, and beta-hydroxyglutarate: explanation of the symptoms in glutaric aciduria?

Glutaric aciduria is a disorcer of lysine, tryptophan, and hydroxylysine metabolism characterized by intermittent metabolic acidemia, dystonia, athetosis and mental retardation. It is due to a recessively inherited deficiency of glutaryl-CoA dehydrogeanse, the enzyme(s) which catalyze the dehydrogenation of glutaryl-CoA to glutaconyl-CoA and decarboxylation of the latter to crotonyl-CoA. Abnormal quantities of glutaric, beta-hydroxyglutaric, and glutaconic acids are found in the urine of these patients. The nature of the movement disorder prompted study of the effects of the abnormally excreted metabolites on brain glutamate decarboxylase, an enzyme implicated in the pathogenesis of Huntington's chorea. Glutamate decarboxylase activity was examined in rat and rabbit brain acetone powders, stabilized with pyridoxal phosphate and glutathione. Glutarate, beta-hydroxyglutarate, and glutaconate were competitive inhibitors of this emzyme, Ki values being 1.3 X 10(-3) mol/l, 2.5 X 10(-4) mol/l, respectively. This inhibition may explain the neurological accompaniments of this syndrome.

Effect of diethylstilbestrol on tissue gain and carcass merit of feedlot beef steers.

The effect of diethylstilbestrol (DES) on the composition of tissue gain of Hereford steers was studied in a complete slaughter balance trial. Eight steers were slaughtered initially (IS) and, after 177 days on feed, eight control steers (C) and seven steers that had been fed 20 mg DES daily (DES) were slaughtered. Initial full body weight averaged 224.8 kg, and final full body weight averaged 403.0 kg for the C steers and 433.6 kg for the DES steers. Final empty body weight averaged 346.6 kg for the C steers and 368.0 kg for the DES steers. DES improved live weight gain by 17% and conversion of feed dry matter to live weight by 12%. Recovery of wet weight during slaughter averaged 99.6%. DES steers had larger rib cut weights and greater proportions of separable lean and bone plus connective tissue in the rib cuts than C steers, an ribeye area tended to be larger in DES steers. DES caused a small shift in relative body composition toward more protein, moisture and ash. Tissue gain in DES steers consisted of 28.3% more protein, 26.0% more moisture, 73.2% more ash, 1.5% less fat and 109.1% more residual (dry matter not accounted for by N x 6.25, ether extract and ash) than did tissue gain in C steers. Energy gain per unit of energy intake over the feeding period was not affected by DES treatment, but DES improved protein gain per unit of protein intake and per unit of energy intake by approximately 20% within the total empty body and by about 25% within the carcass fraction. Results confirm indirect estimates in the literature indicating that DES increases skeletal growth and lean tissue deposition in feedlot steers.

Headaches in children: meeting the challenge of management.

Headaches that interfere with optimal functioning appear as often in children as in adults. Most common are tension (usually psychogenic) headaches. Brain tumors occasionally present as headaches; diagnosis rests on associated signs and symptoms. Migraine may cause frightening headaches, but prognosis is good for relief and long-term remission.

Second malignant neoplasms after cancer in childhood or adolescence. Nordic Society of Paediatric Haematology and Oncology Association of the Nordic Cancer Registries.

OBJECTIVE: To assess the relative risk of developing a second malignant neoplasm in people with a diagnosis of cancer in childhood and adolescence. DESIGN: Register based follow up study. SETTING: Populations of Nordic countries. SUBJECTS: 30,880 people under the age of 20 with a first malignant neoplasm diagnosed during the period 1943-87. MAIN OUTCOME MEASURES: Relative and attributable risks of second malignant neoplasms by type of first cancer, age at first diagnosis, calendar period, sex, and country. Expected figures were based on the appropriate national incidence rates for cancer. RESULTS: 247 cases of second malignant neoplasms were observed in 238 patients, yielding a relative risk for cancer of 3.6 (95% confidence interval 3.1 to 4.1). The risk changed significantly from 2.6 in people first diagnosed during the 1940s and 1950s to 6.9 among cohort members included in the late 1970s and 1980s. Increases were observed for most types of cancer. Highest levels of the relative risk were seen during the 10 years immediately after first malignant diagnosis. The incidence of second malignant neoplasms attributable to the first cancer and associated treatments, however, showed a consistent rise throughout the 45 years of follow up. CONCLUSION: The estimated risks for a second malignant neoplasm were significantly lower than those found in most large hospital based studies but compatible with the results from a similar population based study in the United Kingdom. Extent of risk and cancer pattern were similar among the Nordic countries and are believed to be representative for a large part of the European population.

[Second cancer. Risk of a second malignant neoplasm in persons with cancer in childhood and adolescence]. / Sekundaer cancer. Risiko for sekundoer malign neoplasi hos personer med cancer i barne- og ungdomsår.

Cancer treatments in early life have in previous studies been associated in with high risks of developing a second malignant neoplasm. This study reports on the relative and attributable risks of second malignant neoplasms among 30,880 people under the age of 20, who had been identified in the files of any of the five Nordic cancer registers, 1943-1987. Overall, 247 cases of second malignant neoplasms were observed in 238 patients, yielding a relative risk for cancer of 3.6 (95% confidence interval 3.1-4.1). The risk changed significantly from 2.6 in people first diagnosed during the 1940s and 1950s to 6.9 among cohort members included in the late 1970s and 1980s. Highest levels of the relative risk were seen during the ten years immediately after first malignant diagnosis. The incidence of second malignant neoplasms attributable to the first cancer and associated treatments, however, showed a consistent rise throughout the 45 years of follow up. It was concluded that the estimated risks for second malignant neoplasms were significantly lower than those found in most large hospital based studies but compatible with the results from a similar population based study in the United Kingdom. Extent of risk and cancer pattern were similar among the Nordic countries and are believed to be representative for a large part of the European population.

Cholesterol modulates cell signaling and protein networking by specifically interacting with PDZ domain-containing scaffold proteins.

Cholesterol is known to modulate the physical properties of cell membranes, but its direct involvement in cellular signaling has not been thoroughly investigated. Here we show that cholesterol specifically binds many PDZ domains found in scaffold proteins, including the N-terminal PDZ domain of NHERF1/EBP50. This modular domain has a cholesterol-binding site topologically distinct from its canonical protein-binding site and serves as a dual-specificity domain that bridges the membrane and juxta-membrane signaling complexes. Disruption of the cholesterol-binding activity of NHERF1 largely abrogates its dynamic co-localization with and activation of cystic fibrosis transmembrane conductance regulator, one of its binding partners in the plasma membrane of mammalian cells. At least seven more PDZ domains from other scaffold proteins also bind cholesterol and have cholesterol-binding sites, suggesting that cholesterol modulates cell signaling through direct interactions with these scaffold proteins. This mechanism may provide an alternative explanation for the formation of signaling platforms in cholesterol-rich membrane domains.