Molecular basis for interaction of the protein tyrosine kinase ZAP-70 with the T-cell receptor

The crystal structure of the tandem SH2 domains of human ZAP-70 in complex with a peptide derived from the zeta-subunit of the T-cell receptor reveals an unanticipated interaction between the two domains. A coiled coil of alpha-helices connects the two SH2 domains, producing an interface that constitutes one of the two critical phosphotyrosine binding sites. These and other unique features provide the molecular basis for highly selective association of ZAP-70 with the T-cell receptor.

Crystal structure of the first three domains of the type-1 insulin-like growth factor receptor

The type-1 insulin-like growth-factor receptor (IGF-1R) and insulin receptor (IR) are closely related members of the tyrosine-kinase receptor superfamily. IR is essential for glucose homeostasis, whereas IGF-1R is involved in both normal growth and development and malignant transformation. Homologues of these receptors are found in animals as simple as cnidarians. The epidermal growth-factor receptor (EGFR) family is closely related to the IR family and has significant sequence identity to the extracellular portion we describe here. We now present the structure of the first three domains of IGF-IR (L1-Cys-rich-L2) determined to 2.6 A resolution. The L domains each consist of a single-stranded right-handed beta-helix. The Cys-rich region is composed of eight disulphide-bonded modules, seven of which form a rod-shaped domain with modules associated in an unusual manner. The three domains surround a central space of sufficient size to accommodate a ligand molecule. Although the fragment (residues 1-462) does not bind ligand, many of the determinants responsible for hormone binding and ligand specificity map to this central site. This structure therefore shows how the IR subfamily might interact with their ligands.

The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis

OBJECTIVE

To develop a grading scale to predict the risk of intracerebral hemorrhage (ICH) and prognosis after treatment with IV tissue-plasminogen activator (t-PA) in patients with ischemic stroke.

METHODS

We constructed a five-point scale based on NIH Stroke Scale score, extent of hypodensity on CT scan, serum glucose at baseline, and history of diabetes to predict the risk of hemorrhage after thrombolysis (HAT score). We evaluated the predictive ability of this scale, using c-statistics, in two independent cohorts: the t-PA treated group in the National Institute of Neurological Disorders and Stroke study, and consecutive patients treated with IV t-PA at our institution.

RESULTS

The percentage of patients who developed any ICH after t-PA increased with higher scores in both cohorts. Collectively, the rate of any symptomatic ICH was 2% (0 point), 5% (1 point), 10% (2 points), 15% (3 points), and 44% (>3 points). The c-statistic was 0.72 (95% CI 0.65-0.79; p < 0.001) for all hemorrhages; 0.74 (0.63-0.84; p < 0.001) for symptomatic hemorrhages; and 0.79 (0.70-0.88; p < 0.001) for hemorrhages with final fatal outcome. Similar results were obtained when each cohort was analyzed separately. The score also reasonably predicted good (mRS < or = 2) (c-statistic 0.75; 0.69-0.80; p < 0.001) and catastrophic (mRS > or = 5) (0.78; 0.72-0.84; p < 0.001) functional outcomes on day 90 in the National Institute of Neurological Disorders and Stroke t-PA-treated patients.

CONCLUSIONS

The hemorrhage after thrombolysis (HAT) score is a practical, quick, and easy-to-perform scale that allows reasonable risk stratification of intracerebral hemorrhage after IV tissue-plasminogen activator (t-PA). However, the prognostic value of this scale and its use to predict the net benefit from t-PA needs to be refined and prospectively confirmed in a larger cohort of patients before it can be used in clinical decision-making.

Identification of a determinant of epidermal growth factor receptor ligand-binding specificity using a truncated, high-affinity form of the ectodomain

Murine and human epidermal growth factor receptors (EGFRs) bind human EGF (hEGF), mouse EGF (mEGF), and human transforming growth factor alpha (hTGF-alpha) with high affinity despite the significant differences in the amino acid sequences of the ligands and the receptors. In contrast, the chicken EGFR can discriminate between mEGF (and hEGF) and hTGF-alpha and binds the EGFs with approximately 100-fold lower affinity. The regions responsible for this poor binding are known to be Arg(45) in hEGF and the L2 domain in the chicken EGFR. In this study we have produced a truncated form of the hEGFR ectodomain comprising residues 1-501 (sEGFR501), which, unlike the full-length hEGFR ectodomain (residues 1-621, sEGFR621), binds hEGF and hTGF-alpha with high affinity (K(D) = 13-21 and 35-40 nM, respectively). sEGFR501 was a competitive inhibitor of EGF-stimulated mitogenesis, being almost 10-fold more effective than the full-length EGFR ectodomain and three times more potent than the neutralizing anti-EGFR monoclonal antibody Mab528. Analytical ultracentrifugation showed that the primary EGF binding sites on sEGFR501 were saturated at an equimolar ratio of ligand and receptor, leading to the formation of a 2:2 EGF:sEGFR501 dimer complex. We have used sEGFR501 to generate three mutants with single position substitutions at Glu(367), Gly(441), or Glu(472) to Lys, the residue found in the corresponding positions in the chicken EGFR. All three mutants bound hTGF-alpha and were recognized by Mab528. However, mutant Gly(441)Lys showed markedly reduced binding to hEGF, implicating Gly(441), in the L2 domain, as part of the binding site that recognizes Arg(45) of hEGF.

Quality of life in haemophilia A: Hemophilia Utilization Group Study Va (HUGS-Va)

This study describes health-related quality of life (HRQoL) of persons with haemophilia A in the United States (US) and determines associations between self-reported joint pain, motion limitation and clinically evaluated joint range of motion (ROM), and between HRQoL and ROM. As part of a 2-year cohort study, we collected baseline HRQoL using the SF-12 (adults) and PedsQL (children), along with self-ratings of joint pain and motion limitation, in persons with factor VIII deficiency recruited from six Haemophilia Treatment Centres (HTCs) in geographically diverse regions of the US. Clinically measured joint ROM measurements were collected from medical charts of a subset of participants. Adults (N = 156, mean age: 33.5 ± 12.6 years) had mean physical and mental component scores of 43.4 ± 10.7 and 50.9 ± 10.1, respectively. Children (N = 164, mean age: 9.7 ± 4.5 years) had mean total PedsQL, physical functioning, and psychosocial health scores of 85.9 ± 13.8, 89.5 ± 15.2, and 84.1 ± 15.3, respectively. Persons with more severe haemophilia and higher self-reported joint pain and motion limitation had poorer scores, particularly in the physical aspects of HRQoL. In adults, significant correlations (P < 0.01) were found between ROM measures and both self-reported measures. Except among those with severe disease, children and adults with haemophilia have HRQoL scores comparable with those of the healthy US population. The physical aspects of HRQoL in both adults and children with haemophilia A in the US decrease with increasing severity of illness. However, scores for mental aspects of HRQoL do not differ between severity groups. These findings are comparable with those from studies in European and Canadian haemophilia populations.

The three dimensional structure of the type I insulin-like growth factor receptor

Ever since the discovery of insulin and its role in the regulation of glucose metabolism, there has been great interest in the molecule itself, the insulin-like growth factors (IGFs), and their receptors (IR and IGF-R). These receptors form a subfamily of tyrosine kinase receptors which are large, transmembrane proteins consisting of several structural domains. Their ectodomains have a similar arrangement of two homologous domains (L1 and L2) separated by a Cys rich region. The C-terminal half of their ectodomains consists of three fibronectin type 3 repeats, and an insert domain that contains the alpha-beta cleavage site. This review summarises the key developments in the understanding of the structure of this family of receptors and their relation to other multidomain proteins. Data presented will include multiple sequence analyses, single molecule electron microscope images of the IGF-1R, insulin receptor (IR), and IR-Fab complexes, and the three dimensional structure of the first three domains of the IGF-1R determined to 2.6 A resolution by x ray crystallography. The L domains each adopt a compact shape consisting of a single stranded, right handed beta-helix. The Cys rich region is composed of eight disulphide bonded modules, seven of which form a rod shaped domain with modules associated in an unusual manner.

The dual effect of oxidation on lipid bilayer structure

Sphingomyelin membranes were prepared with different levels of oxidative damage caused by tert-butyl hydroperoxide (TBH). Temperature-induced changes in membrane hydrocarbon chain packing (phase transitions) were monitored using infrared spectroscopy. Lipid phase transition characteristics were evaluated from thermodynamic parameters fitted to the experimental transition curve data. At temperatures below the lipid phase transition Tc, hydrocarbon chains pack in an ordered state whereas above the Tc the hydrocarbon chains pack in a disordered state. Compared to the non-oxidized control, the packing of the hydrocarbon chains of mildly oxidized sphingomyelin (less than 10 nmol TBH/mg lipid) was no different at all temperatures below the Tc, and was more ordered above the Tc. The hydrocarbon chains of strongly oxidized sphingomyelin (greater than 10 nmol TBH/mg lipid) were more disordered at temperatures above and below the Tc compared to the control samples. These results suggest that lipid oxidation has a dual effect on lipid order. A more ordered or disordered state may result depending on the degree of oxidation and the state of lipid order prior to oxidation. These results could be important for explaining the structural changes in oxidized membranes high in sphingomyelin such as those found in the ocular lens and liver plasma membranes.

Removal of cholesterol from blood by affinity binding to heparin-agarose: evaluation on treatment in homozygous familial hypercholesterolemia

Extracorporeal removal of cholesterol from blood with heparin-agarose conjugates was studied as a means of reducing the plasma cholesterol concentration in two patients with homozygous familial hypercholesterolemia. Both patients were treated in an outpatient clinic. Patient 1 underwent two separate courses of treatment; during the first course of eight treatments, the plasma cholesterol concentration decreased by a maximum of 54% (from 811-370 mg/dl). The six treatments in the second course resulted in a 35% reduction of plasma cholesterol (from 939--632 mg/dl). In patient two, 12 consecutive treatments resulted in a 56% decrease in the concentration of plasma cholesterol (from 768--298 mg/dl). Repetitive treatments in both patients resulted in a new "steady state" with circulating cholesterol levels lower than the pretreatment baseline value. The decrease in plasma cholesterol is mainly due to the removal of low density lipoproteins. The circulating level of high density lipoproteins is unaffected by the treatment. The treatment has no effect on the chemical composition of both low and high density lipoproteins. The extracorporeal treatment of blood with heparin-agarose was well tolerated by both patients and there were no undesirable effects. The effectiveness and simplicity of the present approach makes it attractive as a possible mode of therapy for homozygous familial hypercholesterolemia.

Hyperbaric oxygen treatment attenuated the decrease in regional glucose metabolism of rats subjected to focal cerebral ischemia: A high resolution positron emission tomography study

Cerebral hypoxia may be the main component of cell damage caused by ischemia. Previous studies demonstrated a neuroprotective effect of early hyperbaric oxygen (HBO) treatment in various animal models of focal cerebral ischemia. Neuropathologic study showed that exposure of HBO may prevent cell death in ischemic cortex. In the present study, we aimed to assess cellular function of ischemic rat brain after HBO treatment by means of a high-resolution positron emission tomography scanner (microPET) used specifically for small animal imaging. The male Sprague-Dawley rats were subjected to permanent middle cerebral artery occlusion (MCAO), with the regional cerebral blood flow monitored in vivo by laser Doppler flowmetry. One hour after ischemia, HBO therapy (3 atm absolute, 1 h) was initiated. Local cerebral glucose utilization in the ischemic area was measured before, 1 h and 3 h after ischemia, with 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) as a tracer. Neurological deficits and infarct volumes were assessed at 24 h after ischemia. Our study showed that early HBO therapy significantly reduced infarct volume of brain 24 h after ischemia. Moreover, glucose utilization in the ischemic area underwent a severe decrease during 1-3 h after MCAO, while the early HBO treatment significantly attenuated the decrease in cerebral metabolic rate of glucose in the ischemic core of the cortex compared with controls. We report for the first time the application of microPET to quantify the rates of glucose metabolism in the ischemic core of rats exposed to HBO. Our results suggest that the early exposure of HBO can partially reverse the downward trend for glucose utilization in the ischemic core, which might contribute to the reported beneficial effects of early HBO therapy on permanent cerebral ischemia.

Cadmium uptake through the anion exchanger in human red blood cells

1. The initial rate of Cd2+ uptake in human red cells was measured by atomic absorption spectrophotometry. 2. About 96% of Cd2+ uptake was inhibited by DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid) with IC50 (concentration giving 50% of maximal inhibition) of 0.3 microM and by furosemide with IC50 of 500 microM and was resistant to ouabain and amiloride. This indicates the implication of the [Cl(-)-HCO3-] anion exchanger in Cd2+ uptake. 3. DIDS-sensitive Cd2+ uptake required the presence of external HCO3-. HCO3- ions had a biphasic effect on Cd2+ uptake. Low bicarbonate concentrations were stimulatory, suggesting formation of translocating bicarbonate-cadmium complexes. Higher bicarbonate concentrations were inhibitory, suggesting further bicarbonate complexation with formation of non-translocating species. Depending on the presence or absence of external Cl-, a maximal Cd2+ uptake of 1.7 or 0.37 mmol (l cells)-1 h-1 was observed at bicarbonate concentrations of 15.6 or 11 mM respectively. 4. In the presence of bicarbonate, external Cl- ions strongly stimulated Cd2+ uptake, with linear increase between 70 and 125 mM. This suggests that one translocating species may have chloride as ligand. 5. DIDS-sensitive Cd2+ uptake was modestly inhibited by physiological concentrations of external phosphate and was resistant to external K+, Mg2+ and Ca2+. 6. In conclusion, the anion exchanger is the major transport mechanism for red cell cadmium uptake. Translocating species appear to be monovalent anion complexes of cadmium with HCO3- such as [Cd(OH)(HCO3)2]- and [Cd(OH)(HCO3)Cl]-.

Susceptibility-diffusion mismatch predicts thrombolytic outcomes: a retrospective cohort study

BACKGROUND AND PURPOSE

Asymmetric hypointensity of cerebral veins on susceptibility-weighted imaging has been shown to indirectly reflect tissue hypoxia after cerebral ischemia. We therefore investigated whether patients with prominent asymmetry of the cerebral veins on SWI and a relatively small diffusion-weighted imaging lesion (SWI-DWI mismatch), representing the presence of salvageable tissue, were more likely to benefit from thrombolytic therapy.

MATERIALS AND METHODS

We conducted a retrospective study of the anterior circulation of patients with ischemic stroke with SWI/DWI acquired before thrombolysis. The asymmetry index was defined as the ratio of cerebral vein voxel count between the ischemic and normal hemisphere on the SWI phase map. We defined SWI-DWI mismatch as an asymmetry index score of ≥1.75 with a DWI lesion volume of ≤25 mL. Favorable outcome was defined as modified Rankin Scale 0-2 at 3 months. Univariate and multivariate logistic regression analyses were used to examine the association between the mismatch profile and favorable outcome.

RESULTS

Fifty-four patients undergoing thrombolytic treatment were enrolled in this study. The rate of favorable outcome was significantly higher among patients with baseline SWI-DWI mismatch compared with those without (78% versus 44%; adjusted odds ratio, 6.317; 95% CI, 1.12-35.80; P = .037). Patients with SWI-DWI mismatch were also more likely to have a favorable outcome from reperfusion (91% versus 43%, P = .033) or recanalization (100% versus 40%, P = .013). The accuracy of SWI-DWI mismatch for predicting favorable outcome was higher than that of perfusion-diffusion mismatch (63% versus 48.1%).

CONCLUSIONS

The presence of SWI-DWI mismatch may identify patients with ischemia who would benefit from early reperfusion therapy.

Prominence of Medullary Veins on Susceptibility-Weighted Images Provides Prognostic Information in Patients with Subacute Stroke

BACKGROUND AND PURPOSE

The demonstration of prominent medullary veins in the deep white matter ipsilateral to acute ischemic stroke has been shown to predict poor clinical outcome. We have investigated the prognostic implications of prominent medullary veins in patients with subacute stroke who present outside the therapeutic window for revascularization therapy.

MATERIALS AND METHODS

Forty-three consecutive patients with ischemic stroke in the middle cerebral artery territory presenting within 3-7 days of ictus were enrolled. The presence of prominent medullary veins in the periventricular white matter of the ipsilateral and contralateral medullary vein hemispheres was recorded. Perfusion-weighted imaging was used to calculate differences in hemispheric CBF from corresponding areas. Clinical outcome was classified as good if the modified Rankin Scale score was <3.

RESULTS

Prominent medullary veins were observed in 24/43 patients with 14 ipsilateral medullary veins and 10 contralateral medullary veins. The ipsilateral medullary vein was independently associated with poor outcome (odds ratio, 11.19; P = .046). The contralateral medullary vein was not independently predictive of outcome but was significantly more common in patients with good outcome (90.0% contralateral medullary veins). A mean 64.5% decrease and a 52.4% increase of differences in hemispheric CBF were found in ipsilateral medullary veins and contralateral medullary veins, respectively.

CONCLUSIONS

The ipsilateral medullary vein was a significant predictive biomarker of poor clinical outcome after stroke and was associated with hypoperfusion. The contralateral medullary vein was associated with good clinical outcome, and we hypothesize that prominent contralateral medullary veins indirectly reflect increased CBF in the ipsilateral hemisphere due to spontaneous recanalization or collateral flow.

Antimicrobial peptides: An alternative to traditional antibiotics

As antibiotic-resistant bacteria and genes continue to emerge, the identification of effective alternatives to traditional antibiotics has become a pressing issue. Antimicrobial peptides are favored for their safety, low residue, and low resistance properties, and their unique antimicrobial mechanisms show significant potential in combating antibiotic resistance. However, the high production cost and weak activity of antimicrobial peptides limit their application. Moreover, traditional laboratory methods for identifying and designing new antimicrobial peptides are time-consuming and labor-intensive, hindering their development. Currently, novel technologies, such as artificial intelligence (AI) are being employed to develop and design new antimicrobial peptide resources, offering new opportunities for the advancement of antimicrobial peptides. This article summarizes the basic characteristics and antimicrobial mechanisms of antimicrobial peptides, as well as their advantages and limitations, and explores the application of AI in antimicrobial peptides prediction amd design. This highlights the crucial role of AI in enhancing the efficiency of antimicrobial peptide research and provides a reference for antimicrobial drug development.

Whole blood viscosity in preeclampsia

Whole blood viscosity was measured in 41 patients with preeclampsia and in 51 normotensive control subjects. The mean viscosity in the preeclamptic group had a highly significant elevation (t = 9.752, p less than 0.001, at a shear rate of 0.1 sec-1 and t = 4.223, p less than 0.001, at a shear rate of 100 sec-1). The slower shear rate gave the better discrimination between the two groups as only four patients with preeclampsia had a value within 1 SD of the mean of the control group. It is suggested that the measurement of whole blood viscosity may be clinically useful in the management of patients with preeclampsia.

Crystallization of the first three domains of the human insulin-like growth factor-1 receptor

The insulin-like growth factor-1 receptor (IGF-1R) is a tyrosine kinase receptor of central importance in cell proliferation. A fragment (residues 1-462) comprising the L1-cysteine rich-L2 domains of the human IGF-1R ectodomain has been overexpressed in glycosylation-deficient Lec8 cells and has been affinity-purified via a c-myc tag followed by gel filtration. The fragment was recognized by two anti-IGF-1R monoclonal antibodies, 24-31 and 24-60, but showed no detectable binding of IGF-1 or IGF-2. Isocratic elution of IGF-1R/462 on anion-exchange chromatography reduced sample heterogeneity, permitting the production of crystals that diffracted to 2.6 A resolution with cell dimensions a = 77.0 A, b = 99.5 A, c = 120.1 A, and space group P2(1)2(1)2(1).

Physical activity and health outcomes in persons with haemophilia B

Regular participation in physical activity helps to prevent damage and maintain joint health in persons with haemophilia. This study describes self-reported physical activity participation among a sample of people with haemophilia B in the US and measures its association with health-related quality of life (HRQoL). Data on 135 participants aged 5-64 years were abstracted from Hemophilia Utilization Group Study Part Vb. The International Physical Activity Questionnaire assessed physical activity among participants aged 15-64 years, and the Children's Physical Activity Questionnaire abstracted from the Canadian Community Health Survey was used for participants aged 5-14 years. SF-12 was used to measure HRQoL and the EuroQol (EQ-5D-3L) was used to measure health status for participants older than 18 years of age. PedsQL was used to measure HRQoL in children aged 5-18 years. Sixty-two percent of participants in the 15-64 year-old age cohort reported a high level of physical activity, 29% reported moderate activity and 9% reported low activity. For children aged 5-14 years, 79% reported participating in physical activity for at least 4 days over a typical week. Based on the 2008 Physical Activity Guidelines for Americans, 79% of adults achieved the recommended physical activity level. Multivariable regression models indicated that adults who engaged in a high level of physical activity reported EQ-5D Visual Analogue Scale (VAS) scores that were 11.7 (P = 0.0726) points greater than those who engaged in moderate/low activity, indicating better health outcomes. Among children, no statistically significant differences in health outcomes were found between high and moderate or low activity groups.

Distinct predictive role of collateral status on clinical outcome in variant stroke subtypes of acute large arterial occlusion

BACKGROUND AND PURPOSE

Clinical trials have shown that robust collateral flow has a relationship with good clinical outcome; however, different stroke subtypes were lumped together. This study explored the relationship between baseline collaterals and the onset-to-imaging time (OIT) and the correlation between pre-treatment collateral status and clinical outcome amongst different subtypes.

METHOD

Prospectively collected data from consecutive acute ischaemic stroke patients with acute middle cerebral artery occlusion who received reperfusion therapy were reviewed. The regional leptomeningeal score (20 points) was based on the scoring extent of contrast opacification in the six Alberta Stroke Program Early CT Score (ASPECTS) cortical regions (M1-6), parasagittal anterior cerebral artery territory and the basal ganglia by perfusion-derived dynamic four-dimensional computed tomography angiography (4D CTA). Stroke subtype was determined by the TOAST classification criteria. A 3-months modified Rankin Scale score of 0-2 was defined as a good outcome.

RESULTS

The analysis included 158 patients: 30 (19.0%) patients had large artery atherosclerotic stroke (LAA), 87 (55.1%) cardioembolic stroke (CE) and 41 (25.9%) stroke of undetermined etiology. Baseline collateral was negatively correlated with OIT (P = 0.0205) in the CE group after adjusting for female sex, smoking, hyperlipidemia, baseline National Institutes of Health Stroke Scale (NIHSS) and baseline mismatch ratio, but not in the LAA group. Baseline collateral showed a strong relationship with good clinical outcome after adjusting for recanalization, baseline NIHSS, age and female sex (odds ratio 1.120, confidence interval 1.013-1.238, P = 0.027) in all patients and in the CE group (odds ratio 3.223, confidence interval 1.212-8.570, P = 0.019), but not in the LAA patients.

CONCLUSIONS

Based on 4D CTA, sustained good leptomeningeal collaterals may predict good outcome in CE but not in LAA patients. Moreover, the extent of collaterals was associated with OIT in the CE patients, which indicates prompt reperfusion therapy in this group of patients.

Ipsilateral Prominent Thalamostriate Vein on Susceptibility-Weighted Imaging Predicts Poor Outcome after Intravenous Thrombolysis in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

The impact of deep cerebral veins on neurologic outcome after intravenous thrombolysis in patients with acute ischemic stroke is unclear. We investigated the relationship between the appearance of deep cerebral veins on susceptibility-weighted imaging and neurologic outcome in patients who underwent thrombolysis.

MATERIALS AND METHODS

We retrospectively analyzed 109 consecutive patients with acute ischemic stroke who had pretreatment SWI and received intravenous thrombolysis within 6 hours. We calculated the signal difference ratio (defined as the relative difference in signal intensity between the ipsilateral and contralateral veins) of the thalamostriate vein, septal vein, and internal cerebral vein on pretreatment SWI.

RESULTS

Only the signal difference ratio of the thalamostriate vein was significantly associated with poor outcome (3-month modified Rankin Scale score > 2, P = .008). The optimal threshold was relative hypointensity of the ipsilateral vein of >4.8% (sensitivity of 53.7% and specificity of 80.9%). We defined a signal difference ratio of the thalamostriate vein of ≥5% as an ipsilateral prominent thalamostriate vein. Patients with an ipsilateral prominent thalamostriate vein were more likely to have poor outcome (OR = 3.66; 95% CI, 1.25-10.68; P = .02) and a lower rate of successful reperfusion (reperfusion rate of ≥70%; OR = 0.35; 95% CI, 0.13-0.92; P = .03), compared with those without an ipsilateral prominent thalamostriate vein. However, patients with an ipsilateral prominent thalamostriate vein were still less likely to experience poor outcome when reperfusion was achieved compared with when reperfusion did not occur (80.0% versus 44.4%, P = .04).

CONCLUSIONS

A pretreatment ipsilateral prominent thalamostriate vein was associated with reduced reperfusion after thrombolysis and poor outcome. More intensive reperfusion approaches may be required for patients with an ipsilateral prominent thalamostriate vein.

Metallic Hyperdensity Sign on Noncontrast CT Immediately after Mechanical Thrombectomy Predicts Parenchymal Hemorrhage in Patients with Acute Large-Artery Occlusion

BACKGROUND AND PURPOSE

Parenchymal hemorrhage is a severe complication following mechanical recanalization in patients with acute ischemic stroke with large-vessel occlusion. This study aimed to assess whether the metallic hyperdensity sign on noncontrast CT performed immediately after mechanical thrombectomy can predict parenchymal hemorrhage at 24 hours.

MATERIALS AND METHODS

We included consecutive patients with acute ischemic stroke with large-vessel occlusion who underwent noncontrast CT immediately after mechanical thrombectomy between January 2014 and September 2018. The metallic hyperdensity sign was defined as a nonpetechial intracerebral hyperdense lesion (diameter, ≥1 cm) in the basal ganglia and a maximum CT density of >90 HU. The sensitivity, specificity, and positive and negative predictive values of the metallic hyperdensity sign in predicting parenchymal hemorrhage were calculated.

RESULTS

A total of 198 patients were included. The metallic hyperdensity sign was found in 59 (29.7%) patients, and 51 (25.7%) patients had parenchymal hemorrhage at 24 hours. Patients with the metallic hyperdensity sign are more likely to have parenchymal hemorrhage than those without it (76.3% versus 4.3%, P < .001). The sensitivity, specificity, positive predictive value, and negative predictive value of the metallic hyperdensity sign in predicting parenchymal hemorrhage were 88.2%, 90.5%, 76.3%, and 95.7%, respectively.

CONCLUSIONS

The presence of the metallic hyperdensity sign on noncontrast CT performed immediately after mechanical thrombectomy in patients with large-vessel occlusion could predict the occurrence of parenchymal hemorrhage at 24 hours, which might be helpful in postinterventional management within 24 hours after mechanical thrombectomy.

Salidiuretic action by genistein in the isolated, perfused rat kidney

The urinary isoflavonoid genistein inhibits membrane Na-K-Cl cotransporters at similar concentrations as furosemide, but the significance of this action is unknown. Genistein was therefore investigated in rats for its potential salidiuretic actions. In the isolated, perfused rat kidney, genistein induced a maximal salidiuretic action similar to that of furosemide but was 3 to 5 times less potent than furosemide in terms of active doses (natriuresis EC50, 237+/-92 versus 56+/-20 micromol/L for genistein and furosemide, respectively). Genistein and furosemide had no additive salidiuretic actions. Genistein had no significant effect on glomerular filtration rate but was able to significantly reduce renal vascular resistance with respect to vehicle isolated perfused kidney. Indomethacin (10 micromol/L), a blocker of prostaglandin biosynthesis, reduced salidiuresis and renal vasorelaxation by genistein. Subcutaneous genistein (15 mg/kg) induced a statistically significant increase in diuresis and natriuresis with respect to vehicle during the first 6 hours of administration in rats. In conclusion, genistein compares well with furosemide in vitro for its salidiuretic profile and potency in the isolated perfused rat kidney and is also natriuretic by the subcutaneous route in the rat. Further studies are required to investigate potential natriuretic and perhaps hypotensive actions of dietary genistein.

Renal and vascular actions of equol in the rat

BACKGROUND

The urinary isoflavonoid equol inhibits membrane Na-K-Cl cotransporters at similar concentrations to those at which furosemide inhibits them, but the significance of this action is not known.

OBJECTIVE

To investigate the potential salidiuretic and vascular actions of equol in the rat.

METHODS

Renal functioning was assessed in vitro in the isolated perfused kidney and in vivo in conscious rats. The vascular contractility of isolated aorta was assessed.

RESULTS

In the isolated perfused kidney equol was concentrated 50- to 70-fold in the urinary fluid, it was 3-4 times less potent than furosemide at increasing diuresis, natriuresis and kaliuresis (the difference was due to its higher protein-binding affinity), and it induced a modest but significant increase in glomerular filtration rate. In vivo, orally administered equol was a modest natriuretic agent, about 8-fold less potent than orally administered furosemide (in molar terms). In isolated aortic rings precontracted by administration of phenylephrine, administration of equol relaxed the contracted aorta at 10-fold lower concentrations (concentration for half-maximal activity 58.9 +/- 16 micromol/l, n = 3) than did furosemide (concentration for half-maximal activity 633 +/- 145 micromol/l, n = 3).

CONCLUSIONS

Equol is a modest natriuretic and vasorelaxant agent in the rat. Further studies are required in order to investigate the potential natriuretic and perhaps hypotensive actions of dietary equol precursors (daidzein).

Thrombus Permeability on Dynamic CTA Predicts Good Outcome after Reperfusion Therapy

BACKGROUND AND PURPOSE

Thrombus permeability assessed on conventional CTA is associated with neurologic outcome in patients with acute ischemic stroke. We aimed to investigate whether dynamic CTA can improve the accuracy of thrombus permeability assessment and its predictive value for outcome.

MATERIALS AND METHODS

We reviewed consecutive patients with acute ischemic stroke who had occlusion of the M1 segment of the middle artery cerebral artery and underwent pretreatment perfusion CT. Thrombus permeability, determined by thrombus attenuation increase (TAI), was assessed on 26-phase dynamic CTA derived from perfusion CT. TAI_max was defined as the maximum TAI among phases; TAI_peak, as TAI of peak arterial phase; TAI_con, as TAI on phase 13. Good outcome was defined as a 3-month mRS score of ≤2.

RESULTS

One hundred four patients were enrolled in the final analysis. The median TAI_max, TAI_peak, and TAI_con were 30.1 HU (interquartile range, 13.0-50.2 HU), 9.5 HU (interquartile range, -1.6-28.7 HU), and 6.6 HU (interquartile range, -5.1-24.4 HU), respectively. Multivariable regression analyses showed that TAI_max (OR = 1.027; 95% CI, 1.007-1.048; P = .008), TAI_peak (OR = 1.029; 95% CI, 1.005-1.054; P = .020), and TAI_con (OR = 1.026; 95% CI, 1.002-1.051; P = .037) were independently associated with good outcome. The areas under the ROC curve of TAI_max, TAI_peak, and TAI_con in predicting good outcome were 0.734, 0.701, and 0.658, respectively.

CONCLUSIONS

Thrombus permeability assessed on dynamic CTA could be a better predictor of outcome after reperfusion therapy than that assessed on conventional single-phase CTA.

Purification and chemical characterization of a potent inhibitor of the Na-K-Cl cotransport system in rat urine

A potent inhibitor of the Na-K-Cl cotransport system was purified from urines of salt-loaded rats. Mass spectroscopy revealed a molecular mass of 242 Da. Nuclear magnetic resonance showed a spectrum identical to that of 3,4-dihydro-3-(4-hydroxyphenyl)-2H-1-benzopyran-7-ol (an "estrogen-like" isoflavonoid: equol). This compound inhibited cotransport fluxes at similar concentrations (IC50=16-24 microM) as furosemide (IC50 approximately 10 microM). Cotransport inhibitory activity of urines from rats drinking tap water was fully explained by urinary equol concentrations (approximately 27 microM, measured by high-performance liquid chromatography). Slat-loading increased urinary equol excretion, but not sufficiently high to fully explain the very important increase in cotransport inhibitory potency. We conclude that: (i) under basal conditions urinary equol can regulate Na-K-Cl cotransport activity in the kidney and (ii) salt-loading should evoke the appearance of other cotransport inhibitors.