bluuebunny/crossref_metadata_2025 huggingface dataset:
Transforming Growth Factor-β–Induced Inhibition of Myogenesis Is Mediated Through Smad Pathway and Is Modulated by Microtubule Dynamic Stability
Authors: Zhu Shoukang , Goldschmidt-Clermont Pascal J. , Dong Chunming
Published: January 2004

The expression of muscle-specific genes associated with myogenesis is controlled by several myogenic transcription factors, including myogenin and MEF2D. Transforming growth factor-β (TGF-β) has been shown to inhibit myogenesis, yet the molecular mechanisms underlying such inhibition are not known. In the present study, TGF-β was shown to inhibit myogenin and MEF2D expression and myotube formation in C2C12 myoblasts cultured in differentiation medium in a cell density–dependent manner. Transfection of C2C12 cells with Smad7, an antagonist for TGF-β/Smad signaling, restored the capacity of these cells to differentiate in the presence of TGF-β or when cultured in growth medium at low confluence, conditions that hinder muscle differentiation. Moreover, nocodazole, a microtubule-destabilizing agent, enhanced the inhibition of myogenesis exerted by TGF-β, an effect that could be restored by tubulin-polymerizing agent taxol, both of which have been shown to affect Smad-microtubule interaction and regulate TGF-β/Smad signaling. Our results indicate that TGF-β inhibits myogenesis, at least in part, via Smad pathway, and provide evidence that low-dose pharmacological agents taxol and nocodazole can be used as a means to modulate myogenesis without affecting cell survival.
Marrow-Derived Stromal Cells Express Genes Encoding a Broad Spectrum of Arteriogenic Cytokines and Promote In Vitro and In Vivo Arteriogenesis Through Paracrine Mechanisms
Authors: Kinnaird T. , Stabile E. , Burnett M.S. , Lee C.W. , Barr S. , Fuchs S. , Epstein S.E.
Published: January 2004

We recently demonstrated that marrow stromal cells (MSCs) augment collateral remodeling through release of several cytokines such as VEGF and bFGF rather than via cell incorporation into new or remodeling vessels. The present study was designed to characterize the full spectrum of cytokine genes expressed by MSCs and to further examine the role of paracrine mechanisms that underpin their therapeutic potential. Normal human MSCs were cultured under normoxic or hypoxic conditions for 72 hours. The gene expression profile of the cells was determined using Affymetrix GeneChips representing 12 000 genes. A wide array of arteriogenic cytokine genes were expressed at baseline, and several were induced >1.5-fold by hypoxic stress. The gene array data were confirmed using ELISA assays and immunoblotting of the MSC conditioned media (MSC
CM
). MSC
CM
promoted in vitro proliferation and migration of endothelial cells in a dose-dependent manner; anti-VEGF and anti-FGF antibodies only partially attenuated these effects. Similarly, MSC
CM
promoted smooth muscle cell proliferation and migration in a dose-dependent manner. Using a murine hindlimb ischemia model, murine MSC
CM
enhanced collateral flow recovery and remodeling, improved limb function, reduced the incidence of autoamputation, and attenuated muscle atrophy compared with control media. These data indicate that paracrine signaling is an important mediator of bone marrow cell therapy in tissue ischemia, and that cell incorporation into vessels is not a prerequisite for their effects.
Benefit of Clopidogrel Over Aspirin Is Amplified in Patients With a History of Ischemic Events
Authors: Ringleb Peter A. , Bhatt Deepak L. , Hirsch Alan T. , Topol Eric J. , Hacke Werner
Published: January 2004

Background and Purpose—

The goal of this study was to examine the influence of preexisting symptomatic atherosclerotic disease on subsequent ischemic event rates and compare the efficacy of clopidogrel versus aspirin (acetylsalicylic acid, ASA) in patients with such disease.

Methods—

Using the CAPRIE database, we performed multivariate analyses for patients who had symptomatic atherosclerotic disease (ischemic stroke [IS] or myocardial infarction [MI]) in their medical history before enrollment in the Clopidogrel Versus Aspirin in Patients at Risk of Ischemic Events (CAPRIE) trial. Two composite end points were used: (1) IS, MI, or vascular death and (2) IS, MI, or rehospitalization for ischemia.

Results—

In the CAPRIE population, prior IS and MI each were statistically significant predictors of subsequent ischemic events. Compared with the overall population, patients with preexisting symptomatic atherosclerotic disease had elevated event rates for the end point of IS, MI, or vascular death; 3-year rates were 20.4% with clopidogrel and 23.8% with ASA (absolute risk reduction, 3.4%; 95% CI, −0.2 to 7.0; number needed to treat, 29; relative risk reduction, 14.9%;
P
=0.045). Similar results were obtained for the end point of IS, MI, or rehospitalization for ischemia; 3-year event rates were 32.7% with clopidogrel and 36.6% with ASA (absolute risk reduction, 3.9%; 95% CI, −0.4 to 8.1; number needed to treat, 26; relative risk reduction, 12.0%;
P
=0.039).

Conclusions—

CAPRIE patients with a history of prior symptomatic atherosclerotic disease had a high rate of subsequent ischemic events. The absolute benefit of clopidogrel over ASA seemed to be amplified in such high-risk patients.
Collagen Type I α2 (
COL1A2
) Is the Susceptible Gene for Intracranial Aneurysms
Authors: Yoneyama Taku , Kasuya Hidetoshi , Onda Hideaki , Akagawa Hiroyuki , Hashiguchi Kazunari , Nakajima Toshiaki , Hori Tomokatsu , Inoue Ituro
Published: January 2004

Background and Purpose—

The collagen α2(I) gene (
COL1A2
) on chromosome 7q22.1, a positional and functional candidate for intracranial aneurysm (IA), was extensively screened for susceptibility in Japanese IA patients.

Methods—

Twenty-one single nucleotide polymorphisms (SNPs) of
COL1A2
were genotyped in genomic DNA from 260 IA patients (including 115 familial cases) (mean age, 59.9 years) and 293 controls (mean age, 61.6 years). Differences in allelic and genotypic frequencies between the patients and controls were evaluated with the χ
2
test. Circular dichroism spectrometry was monitored with collagen-related peptides that mimic triple-helical models of type I collagen with Ala-459 and Pro-459 to estimate the conformation and stability of alterations.

Results—

Significant genotypic association in the dominant model was observed between an exonic SNP of
COL1A2
and familial IA patients (χ
2
=11.08;
df
=1;
P
=0.00087; odds ratio=3.19; 95% CI, 2.22 to 6.50). This SNP induces Ala to Pro substitution at amino acid 459, located on a triple-helical domain. Circular dichroism spectra showed that the Pro-459 peptide had a higher thermal stability than the Ala-459 peptide.

Conclusions—

The variant of
COL1A2
could be a genetic risk factor for IA patients with family history.
Sex Differences in Carotid Plaque and Stenosis
Authors: Iemolo Francesco , Martiniuk Alexandra , Steinman David A. , Spence J. David
Published: January 2004

Background and Purpose—

Women are relatively protected from cardiovascular events; they are 3 times as likely as men to survive to age 90 years. Although clinical trials show an excess of thrombotic events with estrogen/progestin hormone replacement therapy, much experimental and epidemiological evidence suggests that estrogen may have beneficial effects on endothelial function and atherosclerosis, raising the possibility of sex differences in arterial remodeling. We studied sex differences in carotid plaque and stenosis in relation to survival free of stroke, death, and myocardial infarction.

Methods—

A total of 1686 patients from an atherosclerosis prevention clinic were followed annually for up to 5 years (mean, 2.5±1.3 years) with baseline and follow-up measurements; there were 45 strokes, 94 myocardial infarctions, and 41 deaths.

Results—

Carotid stenosis and plaque increased with age. Women had greater stenosis compared with men (
P
=0.001), whereas men had greater plaque area than did women at all ages (
P
<0.0001). Stroke, myocardial infarction, and death combined were predicted significantly by plaque area (
P
=0.004) but not by stenosis (
P
=0.042).

Conclusions—

Women have more stenosis but less plaque than men, suggesting that differences in sex hormones may affect remodeling of atherosclerosis. Plaque area was a stronger predictor of outcomes than was stenosis.
Functional Magnetic Resonance Imaging Before and After Aphasia Therapy
Authors: Peck Kyung K. , Moore Anna B. , Crosson Bruce A. , Gaiefsky Megan , Gopinath Kaundinya S. , White Keith , Briggs Richard W.
Published: January 2004

Background and Purpose—

Comparing the temporal characteristics of hemodynamic responses in activated cortical regions of aphasic patients before and after therapy would provide insight into the relationship between improved task performance and changes in blood oxygenation level–dependent (BOLD) functional MRI (fMRI) signal. This study investigated differences in the time to peak (TTP) of hemodynamic responses in activated regions of interest (ROIs), before and after therapy, and related them to changes in task performance.

Methods—

Three aphasic patients and 3 controls overtly generated a single exemplar in response to a category. For the patients, TTP of hemodynamic responses in selected ROIs was compared before and after language therapy. The timing differences between auditory cues and verbal responses were compared with TTP differences between auditory and motor cortices.

Results—

The selected ROIs were significantly activated in both aphasic patients and controls during overt word generation. In the aphasic patients, both the timing difference from auditory cues to verbal responses and the TTP difference between auditory and motor cortices decreased after rehabilitation, becoming similar to the values found in controls.

Conclusions—

Findings indicate that (1) rehabilitation increased the speed of word-finding processes; (2) TTP analysis was sensitive to this functional change and can be used to represent improvement in behavior; and (3) it is important to monitor the behavioral performance that might correlate with the temporal pattern of the hemodynamic response.
Increased NADPH-Oxidase Activity and Nox4 Expression During Chronic Hypertension Is Associated With Enhanced Cerebral Vasodilatation to NADPH In Vivo
Authors: Paravicini Tamara M. , Chrissobolis Sophocles , Drummond Grant R. , Sobey Christopher G.
Published: January 2004

Background and Purpose—

We examined the importance of NADPH-oxidase in reactive oxygen species production in cerebral arteries and its effect on vascular tone in vivo. Furthermore, we investigated whether chronic hypertension affects function or expression of this enzyme in cerebral vessels.

Methods—

Superoxide generation was detected in isolated rat basilar arteries with the use of lucigenin-enhanced chemiluminescence. mRNA expression of NADPH-oxidase subunits was assessed by real-time polymerase chain reaction. Basilar artery diameter was measured with the use of a cranial window preparation in anesthetized rats.

Results—

NADPH-stimulated superoxide production was 2.3-fold higher in arteries from spontaneously hypertensive rats (SHR) versus normotensive Wistar-Kyoto rats (WKY) and could be blocked by the NADPH-oxidase inhibitor diphenyleneiodonium. Higher NADPH-oxidase activity was also reflected at the molecular level as mRNA expression of the NADPH-oxidase subunit Nox4 was 4.1-fold higher in basilar arteries from SHR versus WKY. In contrast, expression of Nox1, gp91phox, p22phox, and p47phox did not differ between strains. Application of NADPH to basilar arteries caused larger vasodilatation in SHR than WKY. Vasodilatation to NADPH could be attenuated by diphenyleneiodonium, as well as diethyldithiocarbamate (Cu
2+
/Zn
2+
–superoxide dismutase inhibitor), catalase (H
2
O
2
scavenger), or tetraethylammonium (BK
Ca
channel inhibitor).

Conclusions—

Activation of NADPH-oxidase in cerebral arteries generates superoxide, which is dismutated by Cu
2+
/Zn
2+
–superoxide dismutase to H
2
O
2
. H
2
O
2
then elicits vasodilatation via activation of BK
Ca
channels. Upregulation of Nox4 during chronic hypertension is associated with elevated cerebral artery NADPH-oxidase activity.
Uncomplicated Rapid Posthypothermic Rewarming Alters Cerebrovascular Responsiveness
Authors: Ueda Yuji , Suehiro Eiichi , Wei Enoch P. , Kontos Hermes A. , Povlishock John T.
Published: January 2004

Background and Purpose—

Recently, we focused on the cerebrovascular protective effects of moderate hypothermia after traumatic brain injury, noting that the efficacy of posttraumatic hypothermia is related to the rate of posthypothermic rewarming. In the current communication, we revisit the use of hypothermia with varying degrees of rewarming to ascertain whether, in the normal cerebral vasculature, varying rates of rewarming can differentially affect cerebrovascular responsiveness.

Methods—

Pentobarbital-anesthetized rats equipped with a cranial window were randomized to 3 groups. In 1 group, a 1-hour period of hypothermia (32°C) followed by slow rewarming (over 90 minutes) was used. In the remaining 2 groups, either a 1- or 2-hour period of hypothermia was followed by rapid rewarming (within 30 minutes). Vasoreactivity to hypercapnia and acetylcholine was assessed before, during, and after hypothermia. Additionally, the vascular responses to sodium nitroprusside (SNP) and pinacidil, a K
ATP
channel opener, were also examined.

Results—

Hypothermia itself generated modest vasodilation and reduced vasoreactivity to all utilized agents. The slow rewarming group showed restoration of normal vascular responsivity. In contrast, hypothermia followed by rapid rewarming was associated with continued impaired responsiveness to acetylcholine and arterial hypercapnia. These abnormalities persisted even with the use of more prolonged (2-hour) hypothermia. Furthermore, posthypothermic rapid rewarming impaired the dilator responses of SNP and pinacidil.

Conclusions—

Posthypothermic rapid rewarming caused cerebral vascular abnormalities, including a diminished response to acetylcholine, hypercapnia, pinacidil, and SNP. Our data with acetylcholine and SNP suggest that rapid rewarming most likely causes abnormality at both the vascular smooth muscle and endothelial levels.
Neuroendoscopic Management of Intraventricular Hemorrhage
Authors: Longatti P.L. , Martinuzzi A. , Fiorindi A. , Maistrello L. , Carteri A.
Published: January 2004

Background and Purpose—

We reviewed our 7-year experience in neuroendoscopic management of severe intraventricular hemorrhage (IVH) to evaluate its safety, efficiency, and efficacy.

Methods—

Thirteen patients with spontaneous primary or secondary tetraventricular IVH underwent neuroendoscopy. In all procedures, we used a flexible instrument. CT scans obtained before and after surgery were compared for Graeb score and ventriculocranial ratio. Glasgow Outcome Scale was assessed at 12 months.

Results—

In all patients, the procedure resulted in a substantial removal of ventricular blood. Graeb score was reduced by 65%, and ventriculocranial ratio was reduced by 30% (
P
<0.002). The procedure was carried out safely even in the presence of a vascular malformation, and no rebleeding or delayed hydrocephalus was observed in any case. Mortality at 12 months was 30.7%. Favorable outcome (Glasgow Outcome Scale, 3 to 5) was observed in 61.5% of cases.

Conclusions—

Neuroendoscopic management of severe IVH in this cohort of patients was safe, efficiently reduced the amount of ventricular blood and ventricular dilatation, and effectively produced an outcome profile that compares very favorably with other more conventional treatments.
Magnetic Resonance Imaging Improves Detection of Intracerebral Hemorrhage Over Computed Tomography After Intra-Arterial Thrombolysis
Authors: Greer David M. , Koroshetz Walter J. , Cullen Sean , Gonzalez R. Gilberto , Lev Michael H.
Published: January 2004

Background and Purpose—

Unenhanced CT is routinely performed after intra-arterial (IA) thrombolysis. The presence of residual contrast causing staining of injured brain may mimic intracerebral hemorrhage (ICH). We evaluated MRI with diffusion-weighted imaging (DWI) and susceptibility-weighted imaging (SWI) for detection of ICH after IA thrombolysis, specifically in equivocal areas of hyperdensity seen on postprocedure CT, to help guide the decision to use anticoagulation or antiplatelet therapy after the IA thrombolysis.

Methods—

We performed a retrospective analysis of 15 consecutive patients who underwent IA thrombolysis for acute stroke between September 2000 and March 2003. Inclusion criteria required an immediate postprocedure CT with a questionable hyperdensity and, within the next 48 hours, an MRI with DWI and/or SWI.

Results—

All patients had CT regions of hyperdensity that were equivocal for the presence of ICH. All patients subsequently underwent DWI, and 11 also underwent SWI. Eleven of 15 patients had magnetic susceptibility-induced hypointensity in DWI hyperintensity regions, signifying the presence of acute deoxyhemoglobin. Nine of these patients also received SWI, which confirmed the presence of blood within these regions. Follow-up CT on all 11 patients confirmed ICH. In the 4 patients without DWI susceptibility change, 0 were found to have ICH on either SWI (performed in 2 patients) or follow-up CT. MRI reliably detected the presence of ICH in all patients, whereas CT failed to differentiate contrast staining from hemorrhage in 4 of the 15 patients.

Conclusions—

MRI is an effective means to detect the presence of blood within an equivocal region on post-IA thrombolysis CT. This may influence the decision to use anticoagulation or antiplatelet therapy.
Stroke Magnetic Resonance Imaging Is Accurate in Hyperacute Intracerebral Hemorrhage
Authors: Fiebach Jochen B. , Schellinger Peter D. , Gass Achim , Kucinski Thomas , Siebler Mario , Villringer Arno , Ölkers Peter , Hirsch Jochen G. , Heiland Sabine , Wilde Philipp , Jansen Olav , Röther Joachim , Hacke Werner , Sartor Klaus
Published: January 2004

Background and Purpose—

Although modern multisequence stroke MRI protocols are an emerging imaging routine for the diagnostic assessment of acute ischemic stroke, their sensitivity for intracerebral hemorrhage (ICH), the most important differential diagnosis, is still a matter of debate. We hypothesized that stroke MRI is accurate in the detection of ICH. To evaluate our hypotheses, we conducted a prospective multicenter trial.

Methods—

Stroke MRI protocols of 6 university hospitals were standardized. Images from 62 ICH patients and 62 nonhemorrhagic stroke patients, all imaged within the first 6 hours after symptom onset (mean, 3 hours 18 minutes), were analyzed. For diagnosis of hemorrhage, CT served as the “gold standard.” Three readers experienced in stroke imaging and 3 final-year medical students, unaware of clinical details, separately evaluated sets of diffusion-, T2-, and T2*-weighted images. The extent and phenomenology of the hemorrhage on MRI were assessed separately.

Results—

Mean patient age was 65.5 years; median National Institutes of Health Stroke Scale score was 10. The experienced readers identified ICH with 100% sensitivity (confidence interval, 97.1 to 100) and 100% overall accuracy. Mean ICH size was 17.3 mL (range, 1 to 101.5 mL). The students reached a mean sensitivity of 95.16% (confidence interval, 90.32 to 98.39).

Conclusions—

Hyperacute ICH causes a characteristic imaging pattern on stroke MRI and is detectable with excellent accuracy. Even raters with limited film-reading experience reached good accuracy. Stroke MRI alone can rule out ICH and demonstrate the underlying pathology in hyperacute stroke.
Predictors of Apparent Diffusion Coefficient Normalization in Stroke Patients
Authors: Fiehler Jens , Knudsen Karina , Kucinski Thomas , Kidwell Chelsea S. , Alger Jeffry R. , Thomalla Götz , Eckert Bernd , Wittkugel Oliver , Weiller Cornelius , Zeumer Hermann , Röther Joachim
Published: January 2004

Background and Purpose—

We sought to describe the frequency of normalization of apparent diffusion coefficient (ADC) values that are decreased in hyperacute stroke and to identify characteristics of tissue demonstrating normalization.

Methods—

Sixty-eight acute ischemic stroke patients underwent MRI examination (including diffusion/perfusion imaging and MR angiography) within 6 hours (mean, 2.8 hours) after symptom onset, after 24 hours, and again 4 to 7 days later. Lesion volumes with decreased ADC and delayed time to peak in perfusion imaging were determined. In patients showing ADC normalization, volumes with ADC decrease graded as <50%, 50% to 60%, 60% to 70%, and 70% to 80% of the contralateral value were determined by thresholding. Patients were categorized as normalizers (demonstrating ADC normalization in >5 mL tissue with initially decreased ADC) or nonnormalizers (demonstrating ADC normalization in <5 mL tissue).

Results—

Fourteen patients (19.7%) were classified as normalizers. Eleven of 31 patients (35.5%) initially imaged <3 hours after stroke onset and 3 of 37 (7.5%) of those imaged 3 to 6 hours after onset were normalizers. ADC normalization occurred predominantly in the basal ganglia and white matter after thrombolytic therapy in patients with more distal vessel occlusions. All normalizers demonstrated at least partial tissue reperfusion. Tissue with more severe initial decrease in ADC was less likely to demonstrate normalization.

Conclusions—

ADC normalization is not a rare event in acute stroke after tissue reperfusion. Brain tissue with initially decreased ADC, especially within 3 hours after stroke onset, may include “tissue at risk.”
Predictors of Neurocardiogenic Injury After Subarachnoid Hemorrhage
Authors: Tung Poyee , Kopelnik Alexander , Banki Nader , Ong Ken , Ko Nerissa , Lawton Michael T. , Gress Daryl , Drew Barbara , Foster Elyse , Parmley William , Zaroff Jonathan
Published: January 2004

Background and Purpose—

Subarachnoid hemorrhage (SAH) frequently results in myocardial necrosis with release of cardiac enzymes. Historically, this necrosis has been attributed to coronary artery disease, coronary vasospasm, or oxygen supply-demand mismatch. Experimental evidence, however, indicates that excessive release of norepinephrine from the myocardial sympathetic nerves is the most likely cause. We hypothesized that myocardial necrosis after SAH is a neurally mediated process that is dependent on the severity of neurological injury.

Methods—

Consecutive patients admitted with SAH were enrolled prospectively. Predictor variables reflecting demographic (age, sex, body surface area), hemodynamic (heart rate, systolic blood pressure), treatment (phenylephrine dose), and neurological (Hunt-Hess score) factors were recorded. Serial cardiac troponin I measurements and echocardiography were performed on days 1, 3, and 6 after enrollment. Troponin level was treated as a dichotomous outcome variable. We performed univariate and multivariate analyses on the relationships between the predictor variables and troponin level.

Results—

The study included 223 patients with an average age of 54 years. Twenty percent of the subjects had troponin I levels >1.0 μg/L (range, 0.3 to 50 μg/L). By multivariate logistic regression, a Hunt-Hess score >2, female sex, larger body surface area and left ventricular mass, lower systolic blood pressure, and higher heart rate and phenylephrine dose were independent predictors of troponin elevation.

Conclusions—

The degree of neurological injury as measured by the Hunt-Hess grade is a strong, independent predictor of myocardial necrosis after SAH. This finding supports the hypothesis that cardiac injury after SAH is a neurally mediated process.
NF-κB Activation and Fas Ligand Overexpression in Blood and Plaques of Patients With Carotid Atherosclerosis
Authors: Martín-Ventura José Luis , Blanco-Colio Luis Miguel , Muñoz-García Begoña , Gómez-Hernández Almudena , Arribas Ana , Ortega Luis , Tuñón José , Egido Jesús
Published: January 2004

Background and Purpose—

Apoptosis is present in human atherosclerotic lesions. Nuclear factor-κB (NF-κB) is involved in the transcriptional regulation of the proapoptotic protein Fas ligand (FasL). We have analyzed NF-κB activation and FasL expression in atherosclerotic plaques and peripheral blood mononuclear cells (PBMCs) of patients with carotid stenosis.

Methods—

NF-κB activation and FasL and active caspase-3 expression were analyzed in 32 human carotid plaques. NF-κB activation and FasL mRNA were tested in PBMCs of patients and healthy volunteers. We analyzed whether the NF-κB inhibitor parthenolide regulates FasL expression and cytotoxicity in human T cells.

Results—

The inflammatory region of plaques showed an increase in NF-κB activation (3393±281 versus 1029±100 positive nuclei per mm
2
,
P
<0.001) and FasL (16±1.4% versus 13±1.8%,
P
<0.05) and active caspase-3 (3.3±0.6 versus 1.5±0.3%,
P
<0.05) expression compared with the fibrous area. Activated NF-κB and FasL protein were colocalized in plaque cells. In PBMCs obtained from those patients the day of endarterectomy, NF-κB activation and FasL expression were significantly increased compared with healthy controls (1.5±0.1 versus 0.5±0.1 and 2.1±0.1 versus 1.2±0.1 arbitrary units, respectively;
P
<0.001). There was a significant correlation between NF-κB activation and FasL expression. In activated T cells, parthenolide decreased NF-κB activation, FasL promoter activity, and mRNA expression. Parthenolide also decreased cytotoxicity of activated Jurkat cells on FasL-sensitive cells.

Conclusions—

NF-κB activation and FasL overexpression occur in PBMCs and atherosclerotic lesions of patients with carotid stenosis. The NF-κB-FasL pathway could be involved in the mechanisms underlying plaque instability in humans.
Parametric Perfusion Imaging With Contrast-Enhanced Ultrasound in Acute Ischemic Stroke
Authors: Wiesmann Martin , Meyer Karsten , Albers Thomas , Seidel Günter
Published: January 2004

Background and Purpose—

Color-coded perfusion maps can be calculated from ultrasound harmonic gray-scale imaging data after ultrasound contrast agent bolus injection to analyze brain tissue perfusion. First reports indicate that this method can display cerebral perfusion deficits in acute ischemic stroke. We performed a prospective patient study to evaluate this approach.

Methods—

Thirty consecutive patients suffering from acute middle cerebral artery infarction who presented to our department within 12 hours after symptom onset were investigated with ultrasound perfusion harmonic imaging (PHI) after Levovist bolus injection. Color-coded perfusion maps were calculated from the ultrasound data. In addition, the original gray-scale images were analyzed in cine mode. Findings were compared with those of cranial CT.

Results—

All 30 patients suffered from acute ischemic stroke of the middle cerebral artery territory (median National Institutes of Health Stroke Scale score, 16 points). Twenty-three of the 30 patients (76.7%) had sufficient PHI insonation conditions. In 19 of these 23 patients (82.6%), a marked deficit in contrast enhancement could be visualized by initial PHI with the color-coded parameter images and cine-mode images. In 17 of the 23 (73.9%), the perfusion deficit was found on the parameter images. The area of hypoperfusion in the initial PHI investigation corresponded to the definite area of infarction in follow-up cranial CT. In 3 of 23 patients (13.0%), a perfusion deficit could be demonstrated in PHI, although the supplying artery was found patent by transcranial color-coded duplex sonography.

Conclusions—

With PHI, it is possible to display cerebral perfusion deficits in acute ischemic stroke. PHI yields additional information on the perfusion state of the human brain compared with extracranial and transcranial color-coded duplex sonography.
Pharmacokinetics of Intravenous, Single‐Dose Tiotropium in Subjects with Different Degrees of Renal Impairment
Authors: Türck Dietrich , Weber Werner , Sigmund Ralf , Budde Klemens , Neumayer Hans‐H. , Fritsche Lutz , Rominger Karl‐Ludwig , Feifel Ulrich , Slowinski Torsten
Published: January 2004

Tiotropium, a new potent anticholinergic bronchodilator, is excreted mainly by the kidney. To investigate the pharmacokinetics of tiotropium in renal impairment, the authors evaluated the pharmacokinetics and safety after administration of a single dose of intravenous tiotropium 4.8 μg, given as an infusion over 15 minutes in subjects with normal renal function and a wide range of renal impairment based on measured creatinine clearance (normal: > 80 mL/min, n = 6; mild impairment: > 50–80 mL/min, n = 5; moderate impairment: 30–50 mL/min, n = 7; severe impairment: < 30 mL/min, n = 6). As expected for a drug excreted predominantly in unchanged form by the kidneys, tiotropium plasma concentrations increased as renal impairment worsened, with mean values of 55.5 (16.2 percent geometric coefficient of variation [%gCV]), 77.1 (20.1 %gCV), 101 (29.8 %gCV), and 108 (27.3 %gCV) pg • h/mL for AUC0‐4h in the normal renal function and the mild, moderate, and severe renal impairment groups, respectively. The percentage of tiotropium dose excreted unchanged in the urine decreased from 60.1% of dose (17.7 %gCV) to 59.3% (14.4 %gCV), 39.9% (34.5 %gCV), and 37.4% (10.2 %gCV) in the normal renal function and the mild, moderate, and severe renal impairment groups, respectively. Plasma protein binding of tiotropium did not significantly change in the renal‐impaired subjects. Two subjects with normal renal function experienced headache 10 hours after the infusion, which was mild and transient. No adverse events occurred in subjects with renal impairment. There were no clinically relevant changes in blood pressure, pulse rate, 12‐lead ECG, physical examination, hematology, or clinical chemistry, compared with baseline values, in any subject after intravenous administration of tiotropium. Tiotropium should only be used in patients with moderate to severe renal insufficiency if the potential benefit outweighs the potential risks.
“Cocktail” Approaches and Strategies in Drug Development: Valuable Tool or Flawed Science?
Authors: Zhou Honghui , Tong Zeen , McLeod James F.
Published: January 2004

There is an increasing interest in the simultaneous administration of several probe substrates to characterize the activity of multiple drug‐metabolizing enzymes, the so‐called “cocktail” approach. However, this method remains controversial and is being investigated more extensively. No general consensus has emerged on the applicability of this approach in clinical investigation and during drug development. The objective of the article is to review this important yet specialized technique, as well as its merits, drawbacks, and potential application in drug development. Among the two‐, three‐, four‐, five‐, and six‐drug in vivo cocktails previously evaluated in humans, a variety of substrate probe combinations have been studied. Some probe combinations have been validated not to interact in vivo and have been useful in characterizing drug‐drug interaction potential and metabolic enzyme induction in humans. For drug candidates that affect two or more in vitro pathways or are potential gene inducers, the use of a cocktail approach may facilitate the rapid delineation of the drug candidate's drug interaction potential. It may also offer the potential of providing clear guidance on safely conducting larger clinical studies and limiting comedication restrictions to only those likely to be clinically relevant.
Characterization of the Penetration of Garenoxacin into the Breast Milk of Lactating Women
Authors: Amsden Guy W. , Nicolau David P. , Whitaker Anne‐Marie , Maglio Dana , Bello Akintunde , Russo Rene , Barros Anthony , Gajjar Diptee A.
Published: January 2004

The primary objective of this study was to characterize the extent of excretion of garenoxacin, a novel des‐F(6)‐quinolone antimicrobial, into the breast milk of lactating women. A secondary objective was to determine the time after dose administration that garenoxacin was no longer detected in breast milk so as to define when a mother may resume breastfeeding if it was interrupted for garenoxacin administration. Six healthy, lactating women (age [mean ± SD]: 32 ± 6 years; weight: 68.3 ± 19.8 kg; body mass index: 26 ± 5 kg/m2) who had completed weaning their infants were administered a single 600‐mg oral dose of garenoxacin. Plasma samples were collected predose and repeatedly up to 72 hours postdose. Breast milk was collected predose and for 6‐ to 12‐hour intervals repeatedly up to 120 hours postdose. Breast milk/plasma concentration ratios for garenoxacin ranged from 0.35 to 0.44 up to 24 hours postdose, and the mean peak breast milk concentration was 3.0 μg/mL (0‐ to 6‐h collection interval). Overall, garenoxacin exposure in breast milk was minimal, with a mean of 0.07% of the administered dose recovered within 120 hours. Indeed, garenoxacin was undetectable in the breast milk of a majority of subjects within 84 hours of dosing. As such, an infant nursing from a mother who had received a single 600‐mg oral dose of garenoxacin could theoretically be exposed to 0.42 mg of garenoxacin (0.105 mg/kg/day for a 4‐kg infant over the period of 5 days of nursing). If extrapolated to a 14‐day course of garenoxacin 600 mg once daily, total exposure would be approximately 5.88 mg. These findings indicate that, like other quinolone antimicrobials, garenoxacin is secreted in breast milk.
A Single‐Dose, Two‐Way Crossover, Bioequivalence Study of Dexmethylphenidate HCl with and without Food in Healthy Subjects
Authors: Teo Steve K. , Scheffler Michael R. , Wu Anfan , Stirling David I. , Thomas Steve D. , Stypinski Daria , Khetani Vikram D.
Published: January 2004

Attention deficit hyperactivity disorder (ADHD) in children is effectively treated by racemic oral methylphenidate (dl‐MPH). The d‐isomer (d‐MPH) has been developed as an improved treatment for ADHD since only half the racemic dose is used. This study, performed in healthy subjects, assessed the effect of food on the pharmacokinetics of dexmethylphenidate hydrochloride (d‐MPH HCl) in a single dose (2 × 10‐mg tablets), two‐way crossover with d‐MPH administered to subjects in both a fasting state or after a high‐fat breakfast. There were no serious or unexpected adverse events during the course of this study, with most events reported in comparable numbers of fed and fasted subjects. The bioequivalence of d‐MPH was similar with or without food, with 90% confidence intervals of 88.2% to 104.6% and 105.9% to 118.2% for ln(Cmax) and ln[(AUC0‐∞)], respectively. There was a marginal but statistically significant 1‐hour increase in tmax in the fed versus fasted state, reflecting an absorption delay. The rate of formation of the major metabolite, d‐ritalinic acid (d‐RA), was marginally decreased (∼14%) after food. The extent of exposure to d‐RA was similar (within 1.2%) between both treatments. There was a marginal but statistically significant difference in mean tmax for d‐RA between fed and fasted conditions, with peak concentration occurring 1.5 hours later after d‐MPH administration with food. There was no measurable in vivo chiral inversion of d‐MPH to l‐MPH in plasma. In addition, the metabolism of d‐MPH was stereospecific as d‐MPH only produced d‐RA. In summary, food had no substantial effect on the bioavailability of d‐MPH, with an equivalent rate and extent of exposure obtained. Therefore, d‐MPH can be administered without regard to food intake.
Pharmacokinetics, Tolerability, and Safety of Aripiprazole following Multiple Oral Dosing in Normal Healthy Volunteers
Authors: Mallikaarjun Suresh , Salazar Daniel E. , Bramer Steven L.
Published: January 2004

Two 14‐day, placebo‐controlled, double‐blind studies evaluated the fasting pharmacokinetics, safety, and tolerability of aripiprazole, a new antipsychotic, in healthy male subjects. In Study 1, 37 subjects were randomized to aripiprazole 5 mg, 10 mg, 15 mg, 20 mg, or placebo once daily. In Study 2, 11 subjects were randomized to aripiprazole, titrated from 10 to 30 mg/day, or placebo. Aripiprazole had linear pharmacokinetics over 5 to 30 mg/day, which were described by a two‐compartment open model, with first‐order absorption. In Study 1, mean elimination half‐life ranged from 47 to 68 hours with aripiprazole, with apparent systemic clearance (CL/F) of approximately 3.45 L/h. In Study 2, mean elimination half‐life was 59 hours (CL/F approximately 4.0 L/h). Adverse events were generally mild to moderate, were transient in nature, and commonly occurred within the first 3 days of dosing. Clinical laboratory assessments, electrocardiogram, electroencephalogram, and prolactin levels showed no clinically significant changes during the studies.
Role of Stereoselective Assays in Bioequivalence Studies of Racemic Drugs: Have We Reached a Consensus?
Authors: Srinivas Nuggehally R.
Published: January 2004

The existence of stereoselectivity in metabolism and drug disposition, coupled with the existence of genetic polymorphisms and modulation of enantiomeric kinetics via special delivery systems, provides some compulsion to assess bioequivalence using stereoselective data. However, examination of the literature suggests that nonstereoselective data are commonly used for the bioequivalence assessment of drug racemates.
Teaching Application of Clinical Pharmacology Skills Using Unusual Observations from Clozapine Overdoses
Authors: Pollak P. Timothy , Shafer Steven L.
Published: January 2004

Massive drug overdoses provide a unique opportunity to observe human pharmacokinetic data not otherwise ethically available. They can also provide practical examples for teaching thoughtful application of the principles of clinical pharmacology. Following a case of clozapine overdose in which onset of toxicity was delayed by 72 hours, a probable explanation was found in an exploration of three cases with unusual concentration‐time profiles and revealed unexpected implications for the management of clozapine overdoses. The authors systematically addressed the possible mechanisms proposed in the literature for an unusual plateau in concentrations observed in three clozapine overdoses. The effects that the most commonly suggested explanations (i.e., delayed absorption and saturated or impaired metabolism) would have on both clozapine and norclozapine concentrations were then modeled using the data available from those three cases to provide an objective illustration for comparison. This exercise was then used as a teaching seminar, leading students through the steps required to reach a logical explanation for the observed delayed toxicity and to consider the implications for therapy. Delayed absorption best predicted the sustained serum clozapine and norclozapine concentrations observed in three cases, and modeling suggests that much of the drug remains in the gut, available for absorption for days following an overdose. As a seminar, the exercise provides students with a practical example of the value of systematically ruling out possible explanations by considering what effects various pharmacokinetic alterations would have on observed data. Absorption following massive clozapine overdose appears fundamentally different from that with conventional dosing. This suggests a potential for delayed or prolonged toxicity, extending well beyond the time frame predicted by its half‐life, unless aggressive and sustained efforts are applied to remove clozapine from the gut. Data from drug overdoses provide opportunities to explore unusual aspects of pharmacokinetics, better understand future overdoses of the same agent, and present excellent material for teaching. A seminar illustrating the role that thoughtful application of pharmacologic principles had in addressing this case is now used to introduce the clinical aspects of pharmacology to students at our institutions.
Lumiracoxib: Pharmacokinetic and Pharmacodynamic Profile When Coadministered with Fluconazole in Healthy Subjects
Authors: Scott Graham , Yih Linda , Yeh Ching‐Ming , Milosavljev Slavica , Laurent Aziz , Rordorf Christiane
Published: January 2004

This two‐way crossover study evaluated the effect of fluconazole on the pharmacokinetics and selective COX‐2 inhibition of lumiracoxib. Thirteen healthy subjects were randomized to fluconazole (day 1: 400 mg; days 2–4: 200 mg) or no drug. On day 4, all subjects received a single dose of lumiracoxib (400 mg). Lumiracoxib pharmacokinetics were assessed during the following 48 hours. Thromboxane B2 (TxB2) inhibition was measured prior to lumiracoxib dosing and 2 hours afterwards. Fluconazole caused a small (18%) but not clinically relevant increase in lumiracoxib mean AUC0‐∞ but had no effect on lumiracoxib mean Cmax. The geometric mean ratio (lumiracoxib plus fluconazole/ lumiracoxib alone) for AUC0‐∞ was 1.19 (90% confidence interval [CI] = 1.12, 1.27) and for Cmax was 1.11 (90% CI = 0.98, 1.27). The decrease in TxB2 from predose was not significantly different for lumiracoxib (11.8%) or lumiracoxib plus fluconazole (7.1%); no correlation between lumiracoxib concentration and TxB2 decrease was seen. As fluconazole is a strong inhibitor of cytochrome P450 (CYP) 2C9, other CYP2C9 inhibitors are unlikely to affect lumiracoxib pharmacokinetics with clinical relevance, making dosage adjustment unnecessary.
Pericapillary hemorrhage as criterion of severe human digestive graft-versus-host disease
Authors: Ertault-Daneshpouy Marjan , Leboeuf Christophe , Lemann Marc , Bouhidel Fatiha , Ades Lionel , Gluckman Eliane , Socié Gérard , Janin Anne
Published: January 2004

In an experimental model we demonstrated that endothelial cells of all organs are targets of the alloimmune reaction. Here, in 68 digestive biopsies, we found endothelial lesions by immunohistochemistry and ultrastructure in patients with severe acute graft-versus-host disease (GVHD). In contrast, no such endothelial cell alterations were found either in patients without GVHD or in nongrafted controls. In the biopsies with severe GVHD lesions, ultrastructure showed rupture of the capillary basal membrane and extravased red blood cells. These pericapillary hemorrhages were highly correlated with GVHD severity. In a separate cohort of 39 patients who underwent an allogeneic transplantation after a nonmyeloablative conditioning, 8 patients had intestinal biopsies. Three of these latter patients had both severe pathologic lesions of GVHD and similar endothelial lesions, thus, strengthening the concept that endothelial lesions are linked to GVHD severity and not to the intensity of the conditioning regimen. (Blood. 2004;103:4681-4684)
The granzyme B–serglycin complex from cytotoxic granules requires dynamin for endocytosis
Authors: Veugelers Kirstin , Motyka Bruce , Frantz Christine , Shostak Irene , Sawchuk Tracy , Bleackley R. Chris
Published: January 2004

Cytotoxic T lymphocytes and natural killer cells destroy target cells via the directed exocytosis of lytic effector molecules such as perforin and granzymes. The mechanism by which these proteins enter targets is uncertain. There is ongoing debate over whether the most important endocytic mechanism is nonspecific or is dependent on the cation-independent mannose 6-phosphate receptor. This study tested whether granzyme B endocytosis is facilitated by dynamin, a key factor in many endocytic pathways. Uptake of and killing by the purified granzyme B molecule occurred by both dynamin-dependent and -independent mechanisms. However most importantly, serglycin-bound granzyme B in high-molecular-weight degranulate material from cytotoxic T lymphocytes predominantly followed a dynamin-dependent pathway to kill target cells. Similarly, killing by live cytotoxic T lymphocytes was attenuated by a defect in the dynamin endocytic pathway, and in particular, the pathways characteristically activated by granzyme B were affected. We therefore propose a model where degranulated serglycin-bound granzymes require dynamin for uptake.
Identification and characterization of a very low density lipoprotein receptor-binding peptide from tissue factor pathway inhibitor that has antitumor and antiangiogenic activity
Authors: Hembrough Todd A. , Ruiz Jose F. , Swerdlow Bonnie M. , Swartz Glenn M. , Hammers Hans J. , Zhang Li , Plum Stacy M. , Williams Mark S. , Strickland Dudley K. , Pribluda Victor S.
Published: January 2004

Tissue factor pathway inhibitor (TFPI) is the major physiologic inhibitor of the extrinsic coagulation pathway. We have previously shown that TFPI is also a potent inhibitor of endothelial proliferation in vitro and of primary and metastatic tumor growth in vivo. Surprisingly, the antitumor activity of TFPI was demonstrated to be independent of its anticoagulant activity, suggesting a possible nonhemostatic mechanism of action for TFPI in these models. This antitumor mechanism may involve the very low density lipoprotein (VLDL) receptor because the in vitro antiproliferative activity of TFPI is mediated through interaction with the VLDL receptor. In the current study, we identify a 23-amino acid fragment of TFPI (TFPIc23) localized to the C-terminus, which mediates binding to the VLDL receptor. The TFPIc23 peptide inhibits endothelial cell proliferation through an apoptotic mechanism and blocks vessel outgrowth in the in vitro assays, and this activity is mediated through interaction with the VLDL receptor. In vivo, this peptide potently inhibits angiogenesis in Matrigel and chick chorioallantoic membrane models and also inhibits metastatic tumor growth. Our data demonstrate that this VLDL receptor-binding fragment of the TFPI molecule has apoptotic, antiangiogenic, and antitumor activity and suggests a possible mechanism whereby TFPI can regulate angiogenesis and tumor growth independently of its anticoagulant activity. (Blood. 2004;103: 3374-3380)
Inappropriately low reticulocytosis in severe malarial anemia correlates with suppression in the development of late erythroid precursors
Authors: Chang Kai-Hsin , Tam Mifong , Stevenson Mary M.
Published: January 2004

Inappropriately low reticulocytosis may exacerbate malarial anemia, but the under-lying mechanism is not clear. In this study, naive and infected mice were treated with recombinant murine erythropoietin (EPO), and the upstream events of erythropoiesis affected by blood-stage Plasmodium chabaudi AS were investigated. Malaria infection, with or without EPO treatment, led to a suboptimal increase in TER119+ erythroblasts compared with EPO-treated naive mice. Furthermore, a lower percentage of TER119+ erythroblasts in infected mice were undergoing terminal differentiation to become mature hemoglobin-producing erythroblasts. The impaired maturation of erythroblasts during infection was associated with a shift in the transferrin receptor (CD71) expression from the TER119+ population to B220+ population. Moreover, the suboptimal increase in TER119+ erythroblasts during infection coincided with a blunted proliferative response by splenocytes to EPO stimulation in vitro, although a high frequency of these splenocytes expressed EPO receptor (EPOR). Taken together, these data suggest that during malaria, EPO-induced proliferation of early EPOR-positive erythroid progenitors is suppressed, which may lead to a suboptimal generation of TER119+ erythroblasts. The shift in CD71 expression may result in impaired terminal maturation of these erythroblasts. Thus, inadequate reticulocytosis during malaria is associated with suppressed proliferation, differentiation, and maturation of erythroid precursors.