On synchronization in power-grids modelled as networks of second-order Kuramoto oscillators.

This work concerns analytical results on the role of coupling strength in the phenomenon of onset of complete frequency locking in power-grids modelled as a network of second-order Kuramoto oscillators. Those results allow estimation of the coupling strength for the onset of complete frequency locking and to assess the features of network and oscillators that favor synchronization. The analytical results are evaluated using an order parameter defined as the normalized sum of absolute values of phase deviations of the oscillators over time. The investigation of the frequency synchronization within the subsets of the parameter space involved in the synchronization problem is also carried out. It is shown that the analytical results are in good agreement with those observed in the numerical simulations. In order to illustrate the methodology, a case study is presented, involving the Brazilian high-voltage transmission system under a load peak condition to study the effect of load on the syncronizability of the grid. The results show that both the load and the centralized generation might have concurred to the 2014 blackout.

On the formulation and solution of the isochronal synchronization stability problem in delay-coupled complex networks.

We present a new framework to the formulation of the problem of isochronal synchronization for networks of delay-coupled oscillators. Using a linear transformation to change coordinates of the network state vector, this method allows straightforward definition of the error system, which is a critical step in the formulation of the synchronization problem. The synchronization problem is then solved on the basis of Lyapunov-Krasovskii theorem. Following this approach, we show how the error system can be defined such that its dimension can be the same as (or smaller than) that of the network state vector.

Inactivation of hepatitis A virus by heat and high hydrostatic pressure: variation among laboratory strains.

BACKGROUND AND OBJECTIVES: Hepatitis A virus (HAV) transmission via contaminated blood products has been reported. Cell-adapted HAV strains are generally used to confirm virus inactivation in manufacturing blood products, but the strains may differ in their sensitivity to inactivation treatment. To select an appropriate cell-adapted HAV strain for virus validation, we compared the inactivation efficiency among four strains under two different physical inactivation treatments: heat and high hydrostatic pressure. MATERIALS AND METHODS: The cell-adapted HAV strains used here were KRM238, KRM003 (subgenotype IIIB), KRM031 (IA), and TKM005 (IB). The strains were treated at 60 degrees C for up to 10 h or under high hydrostatic pressure (up to 420 MPa). The reduction in HAV infectivity was measured by an immunofocus-staining method. RESULTS: The heat treatment at 60 degrees C for 10 h reduced HAV infectivity in the range of 3 to 5 log(10) among the strains; KRM238 and TKM005 were harder to inactivate than the other two. The high hydrostatic pressure treatment at 420 MPa also reduced infectivity in the range of 3 to 5 log(10) among the strains, and KRM031 was easier to inactivate than the other strains. CONCLUSION: Heat treatment and high hydrostatic pressure treatment revealed differences in inactivation efficiencies among cell-adapted HAV strains, and each strain reacted differently depending on the treatment. KRM238 may be the best candidate for virus validation to ensure the safety of blood products against viral contamination, as it is harder to inactivate and it replicates better in cell culture than the other strains.

Effect of heat treatment on transformation temperatures and bending properties of nickel-titanium endodontic instruments.

AIM: To investigate the effect of heat treatment on the bending properties of nickel-titanium endodontic instruments in relation to their transformation behaviour. METHODOLOGY: Nickel-titanium super-elastic alloy wire (1.00 mm Ø) was processed into a conical shape with a 0.30 mm diameter tip and 0.06 taper. The heat treatment temperature was set at 440 or 500 degrees C for a period of 10 or 30 min. Nonheat-treated specimens were used as controls. The phase transformation behaviour was examined using differential scanning calorimetry. A cantilever-bending test was used to evaluate the bending properties of the specimens. Data were analyzed by ANOVA and the Tukey-Kramer test (P = 0.05). RESULTS: The transformation temperature was higher for each heat treatment condition compared with the control. Two clear thermal peaks were observed for the heat treatment at 440 degrees C. The specimen heated at 440 degrees C for 30 min exhibited the highest temperatures for M(s) and A(f), with subsequently lower temperatures observed for specimens heated at 440 degrees C for 10 min, 500 degrees C for 30 min, 500 degrees C for 10 min, and control specimens. The sample heated at 440 degrees C for 30 min had the lowest bending load values (P < 0.05), both in the elastic range (0.5 mm deflection) and in the super-elastic range (2.0 mm deflection). The influence of heat treatment time was less than that of heat treatment temperature. CONCLUSIONS: Change in the transformation behaviour by heat treatment may be effective in increasing the flexibility of nickel-titanium endodontic instruments.

Modelling approach to obtain regional respiratory mechanics using electrical impedance tomography and volume-dependent elastance model.

OBJECTIVE: This paper presents a method for breath-by-breath estimation of regional respiratory mechanics without the need for special manoeuvres (such as inspiratory pause or low-flow inflation) using electrical impedance tomography (EIT) associated with pressure/airflow waveforms. APPROACH: We developed a method to estimate regional parameters using the regional impedance fraction, by multiplying it by global flow and volume waveforms. A volume-dependent elastance model was used to obtain compliance, resistance, volume-independent (E 1), and volume-dependent (E 2) components. Three swine under invasive mechanical ventilation were used to assess internal consistency and illustrate potential applications of our method. One animal (case 1) was ventilated with a broad range of tidal volumes to compare the consistency between regional and global resistances and compliances. Two other animals (cases 2 and 3) had respiratory compliance decreased, respectively, by overdistension and collapse as quantified by x-ray computed tomography. MAIN RESULTS: In case 1, derived global estimates obtained from the independent regional estimates were strongly associated with direct measurements of global mechanics (correlation coefficients of 0.9976 and 0.9981 for compliances and resistances, respectively), suggesting consistency of our modelling. In cases 2 and 3, the development of lung overdistension and collapse over time was captured by regional estimates. CONCLUSIONS: Using EIT and pressure/airflow waveforms, regional respiratory parameters can be obtained cycle-by-cycle, refining lung function monitoring. SIGNIFICANCE: The method allows real-time monitoring of regional parameters and their trends over time, which might be helpful to differentiate deterioration in lung compliance due to overdistension or collapse.

Professional oral health care reduces the number of oropharyngeal bacteria.

Silent aspiration of oropharyngeal pathogenic organisms is a significant risk factor causing pneumonia in the elderly. We hypothesized that regular oral hygiene care will affect the presence of oropharyngeal bacteria. Professional cleaning of the oral cavity and/or the gargling of a disinfectant liquid solution was performed over a five-month period in three facilities for the dependent elderly. Total oropharyngeal bacteria, streptococci, staphylococci, Candida, Pseudomonas, and black-pigmented Bacteroides species were monitored. The levels of these oropharyngeal bacteria decreased or disappeared after weekly professional oral health care, i.e., cleaning of teeth, dentures, tongue, and oral mucous membrane by dental hygienists. After lunch, gargling with povidone iodine was shown to be less effective than professional oral care. These findings indicate that weekly professional mechanical cleaning of the oral cavity, rather than a daily chemical disinfection of the mouth, can be an important strategy to prevent aspiration pneumonia in the dependent elderly.

Condyloma Acuminata of the Urethra in a Male Renal Transplant Recipient: A Case Report.

BACKGROUND: Condyloma acuminatum (CA) is a common sexually transmitted disease associated with human papilloma virus (HPV). CA occurring in the urethra is rare and has not been reported in male renal transplant recipients. In addition, despite immunosuppressive conditions and increased risk of HPV-related malignant neoplasms in transplant recipients, HPV testing in male transplant recipients has been uncommon. Here we report a case of urethral CA in a male deceased donor renal transplantation recipient and discuss the importance of HPV testing in male transplant recipients. CASE PRESENTATION: A 33-year-old male deceased donor renal transplant recipient presented with miction pain 5 years after the transplantation. He reported repeated urinary tract infections with no sexual contact since the renal transplantation. Multiple papillary tumors in his penile urethra were detected by cystoscopy, and a biopsy sample was pathologically diagnosed with CA. Transurethral tumor resection was performed, and the tumors were completely resected. Additional HPV risk type screening with a urethral smear sample showed the prevalence of low-risk HPV. Although tacrolimus was switched to everolimus and imiquimod cream was administered, the tumors recurred 6 months after the resection, and a second resection was performed. No further recurrence has been observed for 1 year to date. CONCLUSION: As the urethral CA was possibly related to immunosuppressive conditions and a risk for HPV-related malignant neoplasm, the case required careful diagnosis, including HPV risk type. The methodology of sampling for HPV testing in men has not been established. This case suggests the necessity for further discussion about HPV testing in male transplant recipients.

Partial Cystectomy of Paraganglioma of the Urinary Bladder Before Living Kidney Transplantation: Case Report.

BACKGROUND: Paraganglioma (extra-adrenal pheochromocytoma) of the bladder is a very rare disease, accounting for 0.06% of all bladder tumors. Optimal management of bladder paraganglioma before kidney transplantation is unknown. We report a case of partial cystectomy for urinary bladder paraganglioma before living kidney transplantation. CASE PRESENTATION: A 59-year-old man with a 27-year history of hemodialysis was referred to our department for further examination of a bladder tumor detected during pre-transplantation testing. Cystoscopy revealed a submucosal tumor on the right side of the bladder. The patient experienced a hypertensive crisis during transurethral resection of the bladder tumor. Endocrinologic and pathologic examinations confirmed the diagnosis of paraganglioma in the urinary bladder. A partial cystectomy was performed before kidney transplantation. Nine months after partial cystectomy, the patient underwent AB0-incompatible living kidney transplantation from his spouse. No disease recurrence or graft rejection was observed 12 months after the transplantation. CONCLUSIONS: To our knowledge, this is the 1st report on the management of paraganglioma in the urinary bladder before living kidney transplantation. Kidney transplantation after partial cystectomy is an option that may be considered in patients with paraganglioma of the urinary bladder, with careful observations of bladder function and vesicoureteral reflux to the grafts.

Slow Progression of Aortic Calcification Is a Potential Benefit of Pre-emptive Kidney Transplantation.

PURPOSE: Pre-emptive kidney transplantation (PKT) is expected to improve graft and cardiovascular event-free survival compared with standard kidney transplantation. Aortic calcification is reported to be closely associated with renal dysfunction and cardiovascular events; however, its implication in PKT recipients remains incompletely explored. This aim of this study was to evaluate whether PKT confers a protective effect on aortic calcification, renal function, graft survival, and cardiovascular event-free survival. METHODS: One hundred adult patients who underwent renal transplantation between January 1996 and March 2016 at Hirosaki University Hospital and Oyokyo Kidney Research Institute were included. Among them, 19 underwent PKT and 81 patients underwent pretransplant dialysis. We retrospectively compared pretransplant and post-transplant aortic calcification index (ACI), renal function (estimated glomerular filtration rate [eGFR]), and graft and cardiovascular event-free survivals between the 2 groups. RESULTS: The median age of this cohort was 45 years. Preoperative ACI was significantly lower in PKT recipients. There were no significant differences between the 2 groups regarding postoperative eGFR, graft survival, and cardiovascular event-free survival. However, the ACI progression rate (ΔACI/y) was significantly lower in PKT recipients than in those who underwent pretransplant dialysis. Higher ACI was significantly associated with poor cardiovascular event-free survival. CONCLUSIONS: PKT is beneficial in that it contributes to the slow progression of after transplantation. Although we could not observe significant differences in graft and cardiovascular event-free survivals between the 2 groups, slow progression of aortic calcification showed a potential to decrease cardiovascular events in PKT recipients during long-term follow-up.

Case-control study on histologically determined multiple primary lung cancer.

Between 1965 and 1985, 72 (64 male and 8 female) cases of multiple primary lung cancer (MPLC) in the National Cancer Center Hospital, Japan, were reviewed, and a retrospective hospital-based case-control study was performed with special reference to the patients' smoking and family histories. Control cases were selected from patients with unicentric lung cancer (ULC) with a longer survival time than that for other patients with whom they were matched for age, sex, histologic examination of primary lung cancer, and residence in prefecture. The overall percentage of MPLC was higher in males (3.1%) than in females (1.8%). Of the total number of cases, 46 were synchronous and 26, metachronous. The same histology was recognized in 38 cases (53%), and squamous cell carcinomas were observed in 65% of MPLC cases, all of whom were smokers. At least half of the MPLC found in nonsmokers were adenocarcinomas. Habitual smokers, with a Brinkman index (BI) of more than 50, accounted for 90% of all cases of MPLC, although 81% of the controls were also habitual smokers. A positive relationship dependent on the number of cigarettes smoked was observed between the BI of smokers and the proportion suffering MPLC. There was a family history of cancer in 47% of MPLC cases while, for controls, this figure was 40%. It was found that 67% of patients with MPLC and 61% with ULC were drinkers. The influence of cigarette smoking on MPLC was confirmed, especially in the cases of squamous cell carcinoma and small-cell carcinoma.

Elevation of glycoprotein galactosyltransferase activity in human lung cancer related to histological types.

Uridine diphosphogalactose:glycoprotein galactosyltransferases were examined in human lung adenocarcinoma and squamous cell carcinoma. The galactosyltransferase activities in tissue homogenates from both carcinomas were higher than in adjacent normal control with asialoagalactofetuin as a substrate. This activity in adenocarcinoma (27 cases) was two times higher than that in squamous cell carcinoma (19 cases) with statistical significance (p less than 0.001). Using Triton-solubilized enzymes from a particulate fraction, similar differences in the activity were observed with ovalbumin, asialoagalactofetuin, and its beta-eliminated derivative as acceptors but not with bovine submaxillary mucin. These observations mean that the higher activity of galactosyltransferase(s) in lung carcinomas (especially in adenocarcinoma) is mainly responsible for galactosylation of carbohydrate chains in N-glycoside-type but not O-glycoside-type glycoproteins.

Elevated activities and properties of arylsulfatases A and B and B-variant in human lung tumors.

The activities of arylsulfatases A and B were determined in human primary and secondary tumor tissues (total, 53 cases) of various histological types. Significantly higher activities of these sulfatases were found in almost all the primary lung carcinomas as compared to their corresponding uninvolved tissues. No significant correlation was demonstrated between the enzyme activities and histological figures (stroma amounts, etc.). Lung adenocarcinoma and squamous cell carcinoma showed the presence of an additional arylsulfatase component (B1) which was not detected in normal human lung. The tumor arylsulfatase B1 had an isoelectric point (pI) of 6.7 and was clearly distinguished from arylsulfatase A (pI 4.9) and arylsulfatase B (pI 9.1 to 9.2) in normal lung and lung tumor. The tumor B1 enzyme was demonstrated to be most probably an isoenzyme of arylsulfatase B, since this unusual enzyme was indistinguishable from arylsulfatase B in terms of Ag+ inhibition; its kinetic parameters of Km for p-nitrocatechol sulfate, which was 2.9 mM with B1; optimum pH of 6.3 for B1; heat stability; and substrate specificity for three synthetic and two physiological substrates.

Measurement of residual platelet thrombogenicity under arterial shear conditions in cerebrovascular disease patients receiving antiplatelet therapy.

UNLABELLED: Essentials A consensus methodology for assessing the effects of antiplatelet agents has not been established. Measuring platelet thrombus formation (PTF) for evaluating antiplatelet effects was assessed. PTF differentially reflected antiplatelet effects compared to other tests. PTF may be associated with the severity of carotid or intracranial arterial stenosis. Click to hear a presentation on platelet function testing in the clinic by Gresele and colleagues SUMMARY: Background A consensus methodology for assessing the effects of antiplatelet agents has not been established. Objective We investigated the usefulness of directly measuring platelet thrombus formation (PTF) using a microchip-based flow chamber system for evaluating antiplatelet therapy. Patients/Methods Platelet thrombus formation in the whole blood of 94 patients with ischemic cerebrovascular disease treated with clopidogrel and/or aspirin was measured in a flow chamber system at a shear rate of 1500 s(-1) and was compared with the results of assays for agonist-induced platelet aggregability, phosphorylation of vasodilator-stimulated phosphoprotein, platelet p-selectin expression (PS), and platelet-monocyte complexes. Results In all patients tested, area under the flow pressure curve (AUC10), which represents platelet thrombogenicity, showed weak correlation with platelet aggregation induced by either adenosine diphosphate or collagen. In addition, AUC10 was lower in patients treated with dual antiplatelet therapy (median 79.4) compared with patients treated with aspirin or clopidogrel alone (217.7 and 301.0, respectively), whereas the parameters evaluated by the other assays did not reflect the combined treatment efficacy. In clopidogrel monotherapy patients, AUC10 was associated with the severity of arterial stenosis (R(2) = 0.127, ß = 1.25), and AUC10 and PS were higher in patients with severe carotid or intracranial arterial stenosis than in those with mild stenosis. Conclusions Platelet thrombus formation measurement using a flow-chamber system was useful for evaluating the efficacy of treatment with aspirin and clopidogrel, both alone and in combination. The present findings indicate that high residual platelet thrombogenicity in patients treated with clopidogrel may be associated with the severity of carotid or intracranial arterial stenosis.

Safety and Effectiveness of Marginal Donor in Living Kidney Transplantation.

BACKGROUND: We evaluated the safety and feasibility of living kidney transplantation from marginal donors. PATIENTS AND METHODS: Between June 2006 and March 2015, we performed 61 living related renal transplantations at two renal transplantation centers. Marginal donors were defined as those who were older than 70 years or who had hypertension, reduced renal function, body mass index greater than 30 kg/m(2), or mildly impaired glucose tolerance. We retrospectively compared renal function and graft survival between marginal and standard living donor kidney transplantations. To evaluate renal function, creatinine clearance (CCr) was preoperatively used for donors, and estimated glomerular filtration rate (eGFR) was postoperatively used for donors and recipients. RESULTS: Among 61 donors, 14 (23%) met the marginal criteria, the major reason being hypertension (91%). The mean age tended to be higher in the marginal group. Preoperative eGFR was significantly lower in the marginal group, whereas postoperative renal function decline ratio at two years was not significantly different between the groups (67% vs 67%, P = .960). Five-year graft survival rates were not significantly different between the two groups. However, recipient eGFR 1 year after kidney transplantation was lower in the marginal group than in the standard group (44 ± 8 vs 55 ± 9 in eGFR, P = .003). CONCLUSIONS: No significant differences were observed between the groups regarding donor renal function. Careful marginal donor selection can be safe and feasible for donors and recipients of living kidney transplantation; however, it may have a negative impact on recipient renal function.

Diabetic environment and genetic predisposition as causes of congenital malformations in NOD mouse embryos.

Congenital malformations such as neural tube defects and a kinky or waved vertebral column were observed at higher incidence in embryos from nonobese diabetic (NOD) female mice with overt diabetes (NOD-D; 40.3%, P less than 0.005) or without overt diabetes (NOD-N; 8.4%, P less than 0.05) than in control Institute of Cancer Research (ICR) mouse embryos (1%) at day 13 of gestation. In vivo and in vitro preimplantation development of NOD-N, NOD-D, and ICR embryos did not differ in rate of development, size, or morphology. Embryos cultured from one-cell to early blastocyst stage were mutually transferred to uterine horns of pseudopregnant females between NOD-D and ICR mice and examined at day 13 of gestation. There were significant decreases in ratios of implantation and of viable embryos in ICR embryos transferred to NOD-D recipients (52%, P less than 0.001 and 14%, P less than 0.001, respectively) compared with those ratios in ICR embryos transferred to ICR uteri (79.2 and 56.2%) or those in NOD-D embryos transferred to ICR uteri (70.3 and 33.1%). Furthermore, 18 of 45 viable ICR embryos transferred to NOD-D dams had malformations, whereas there were no malformations in 73 viable ICR embryos transferred to ICR recipients, suggesting deleterious effects of maternal diabetic environment to embryos. On the other hand, 8 of 58 viable NOD-D embryos that were cultured in vitro and transferred to ICR uteri had malformations such as neural tube defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Randomised clinical trial: safety, tolerability, pharmacokinetics and pharmacodynamics of repeated doses of TAK-438 (vonoprazan), a novel potassium-competitive acid blocker, in healthy male subjects.

BACKGROUND: TAK-438 (vonoprazan) is a potassium-competitive acid blocker that reversibly inhibits gastric H(+) , K(+) -ATPase. AIM: To evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of TAK-438 in healthy Japanese and non-Japanese men. METHODS: In two Phase I, randomised, double-blind, placebo-controlled studies, healthy men (Japan N = 60; UK N = 48) received TAK-438 10-40 mg once daily at a fixed dose level for 7 consecutive days. Assessments included safety, tolerability, pharmacokinetics and pharmacodynamics (intragastric pH). RESULTS: Plasma concentration-time profiles of TAK-438 at all dose levels showed rapid absorption (median Tmax ≤2 h). Mean elimination half-life was up to 9 h. Exposure was slightly greater than dose proportional, with no apparent time-dependent inhibition of metabolism. There was no important difference between the two studies in AUC0-tau on Day 7. TAK-438 caused dose-dependent acid suppression. On Day 7, mean 24-h intragastric pH>4 holding time ratio (HTR) with 40 mg TAK-438 was 100% (Japan) and 93.2% (UK), and mean night-time pH>4 HTR was 100% (Japan) and 90.4% (UK). TAK-438 was well tolerated. The frequency of adverse events was similar at all dose levels and there were no serious adverse events. There were no important increases in serum alanine transaminase activity. Serum gastrin and pepsinogen I and II concentrations increased with TAK-438 dose. CONCLUSIONS: TAK-438 in multiple rising oral dose levels of 10-40 mg once daily for 7 days was safe and well tolerated in healthy men and caused rapid, profound and sustained suppression of gastric acid secretion throughout each 24-h dosing interval. Clinicaltrials.gov identifiers: NCT02123953 and NCT02141711.

Tiered approaches to chromatographic bioanalytical method performance evaluation: recommendation for best practices and harmonization from the Global Bioanalysis Consortium harmonization team.

The A2 harmonization team, a part of the Global Bioanalysis Consortium (GBC), focused on defining possible tiers of chromatographic-based bioanalytical method performance. The need for developing bioanalytical methods suitable for the intended use is not a new proposal and is already referenced in regulatory guidance language. However, the practical implementation of approaches that differ from the well-established full validation requirements has proven challenging. Advances in technologies, the need to progress drug development more efficiently, and emerging new drug compound classes support the use of categorized tiers of bioanalytical methods. This paper incorporated the input from an international team of experienced bioanalysts to surmise the advantages and the challenges of tiered approaches and to provide recommendations on paths forward.

Lymphovascular invasion is significantly associated with biochemical relapse after radical prostatectomy even in patients with pT2N0 negative resection margin.

BACKGROUND: The significance of lymphovascular invasion (LVI) remains controversial, and the association of LVI with biochemical relapse was investigated in men treated with radical prostatectomy according to pathological results. METHODS: Data from 1268 patients undergoing radical prostatectomy between 2000 and 2009 were retrospectively reviewed. Clinicopathological variables were compared between LVI-negative and LVI-positive patients. Multivariate analyses by Cox proportional hazard model and Kaplan-Meier method were performed to identify risk factors for biochemical relapse in all patients, patients with pT2N0 and pT2N0 negative resection margin (RM). RESULTS: LVI information was available in 1160 cases, and LVI was seen in 121 cases (10.4%). Clinicopathological variables were significantly worse in LVI-positive patients than in LVI-negative patients. On multivariate analyses, PSA⩾10 ng ml(-1), pathological Gleason score ⩾8, pathological T stage ⩾3, lymph node metastasis, positive RM and LVI were independent predictors for biochemical relapse in all patients. In patients with pT2N0, PSA⩾10 ng ml(-1), pathological Gleason score ⩾8, positive RM and LVI were independent predictors for biochemical relapse. In patients with pT2N0 negative RM, LVI and pathological Gleason score ⩾8 were independent predictors for biochemical relapse (LVI; hazard ratio 3.809, 95% confidence interval 1.900-7.635, P-value<0.001, Gleason score ⩾8; hazard ratio 2.189, 95% confidence interval 1.199-3.999, P-value=0.011). With a median follow-up of 50 months, 5-year biochemical relapse-free survival in patients with pT2N0 negative RM was 95.7% in those with negative LVI in comparison to 85.3% in those with positive LVI (P<0.001, log rank). CONCLUSIONS: LVI was consistently a significant predictor for biochemical relapse after radical prostatectomy in not only all patients but also in patients with pT2N0 and pT2N0 negative RM. These results strongly support the significance of LVI as a predictor for biochemical relapse.

Ligand binding to the inhibitory and stimulatory GTP cyclohydrolase I/GTP cyclohydrolase I feedback regulatory protein complexes.

GTP cyclohydrolase I feedback regulatory protein (GFRP) mediates feedback inhibition of GTP cyclohydrolase I activity by 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4), which is an essential cofactor for key enzymes producing catecholamines, serotonin, and nitric oxide as well as phenylalanine hydroxylase. GFRP also mediates feed-forward stimulation of GTP cyclohydrolase I activity by phenylalanine at subsaturating GTP levels. These ligands, BH4 and phenylalanine, induce complex formation between one molecule of GTP cyclohydrolase I and two molecules of GFRP. Here, we report the analysis of ligand binding using the gel filtration method of Hummel and Dreyer. BH4 binds to the GTP cyclohydrolase I/GFRP complex with a Kd of 4 microM, and phenylalanine binds to the protein complex with a Kd of 94 microM. The binding of BH4 is enhanced by dGTP. The binding stoichiometrics of BH4 and phenylalanine were estimated to be 10 molecules of each per protein complex, in other words, one molecule per subunit of protein, because GTP cyclohydrolase I is a decamer and GFRP is a pentamer. These findings were corroborated by data from equilibrium dialysis experiments. Regarding ligand binding to free proteins, BH4 binds weakly to GTP cyclohydrolase I but not to GFRP, and phenylalanine binds weakly to GFRP but not to GTP cyclohydrolase I. These results suggest that the overall structure of the protein complex contributes to binding of BH4 and phenylalanine but also that each binding site of BH4 and phenylalanine may be primarily composed of residues of GTP cyclohydrolase I and GFRP, respectively.

Parenchymal hyperdensity on computed tomography after intra-arterial reperfusion therapy for acute middle cerebral artery occlusion: incidence and clinical significance.

BACKGROUND AND PURPOSE: The purpose of the present study was to assess the incidence and clinical significance of the intraparenchymal hyperdense areas on the posttherapeutic CT scan just after intra-arterial reperfusion therapy. METHODS: Seventy-seven patients with acute middle cerebral artery occlusion were studied prospectively with post-therapeutic CT. Hyperdense areas were classified into three groups: those in the lentiform nucleus, insular cortex and cerebral cortex. We investigated the incidence of hyperdense areas and hemorrhagic transformations and assessed whether location of hyperdense areas may play a role in the incidence of hemorrhagic transformations. We also evaluated correlation between early CT signs and hyperdense areas. RESULTS: Forty-five hyperdense areas were seen in 37 of the 77 patients (48.1%): 19 of the 45 (42.2%) were confirmed to be hematomas themselves, 6 (13.4%) showed later conversion to petechial hemorrhages, and 20 (44.4%) showed rapid disappearance without hemorrhagic transformations. Eleven of the 37 patients (29.7%) had neurological worsening due to massive hematoma (symptomatic hemorrhage), whereas none of the 40 patients without hyperdense areas had symptomatic hemorrhage. The incidence of hemorrhage among hyperdense areas was significantly lower in the insular cortex than in the other 2 regions (P<0.01). On the other hand, hyperdense areas in the lentiform nucleus had a significantly higher incidence of neurological worsening (P<0.05). There was a significant correlation between early CT signs and hyperdense areas (P<0.0001). CONCLUSIONS: The presence of hyperdense areas was a significant risk factor for severe hemorrhagic transformations, although only 29.7% of patients with hyperdense areas had symptomatic hemorrhage. On the contrary, the absence of hyperdense areas was a reliable negative predictor for symptomatic hemorrhage.