Toluidine blue-mediated photodynamic therapy of oral wound infections in rats

The purpose of this study was to examine the effect of toluidine blue (TB)-mediated photodynamic therapy (PDT) on oral wound infections in rats. The study called for a combination treatment of a 1mg/ml solution of TB with a red light at three intensity settings of 12 J/cm(2), 24 J/cm(2) and 48 J/cm(2). In the group that was given the highest light dose of 48 J/cm(2), an average kill rate of approximately 97% was achieved. A lesser killing effect was achieved in the group that was subjected to the lowest light dose of 12 J/cm(2), where an average of approximately 25% of the bacteria survived. After PDT, the lesions were allowed to develop, and the peak size of the lesions was larger in the control group than in the test groups, especially for the 48 J/cm(2) group. We also observed that in the 24 J/cm(2) and 48 J/cm(2) groups the lesions were of significantly smaller size. Our study demonstrated that combined TB-PDT therapy can successfully treat oral wound infections in rats. These promising results recommend the use of this treatment as a possible alternative to topical anti-microbials in future clinical applications.

Measurement of milk D-3-hydroxybutyrate with a simple UV spectrophotometer method: an alternative assay method

The measurement of D-3-hydroxybutyrate (D-BHBA) in milk samples is an important tool for diagnosis of subclinical/clinical ketosis in dairy cows. We describe a simple UV spectrophotometric method for measuring the concentration of D-BHBA in milk of dairy cows. From two herds, 119 milk samples were taken from dairy cows. The standard-curve equation was y = 0.2582x + 0.0269 (R2 = 0.9967). The assay was highly specific with a minimum detection limit of 0.01 mmol/L and measuring range of up to 5 mmol/L. The recovery was between 99.35% and 100.22% and repeatability was 99.8%. The comparison between the spectrophotometric method and the fluorometric method revealed a close correlation (r = 0.9939). These results show that the spectrophotometric method can be successfully used as an alternative method to measure D-BHBA content in milk.

The Notch pathway mediates expansion of a progenitor pool and neuronal differentiation in adult neural progenitor cells after stroke

Molecular mechanisms by which stroke increases neurogenesis have not been fully investigated. Using neural progenitor cells isolated from the subventricular zone (SVZ) of the adult rat subjected to focal cerebral ischemia, we investigated the Notch pathway in regulating proliferation and differentiation of adult neural progenitor cells after stroke. During proliferation of neural progenitor cells, ischemic neural progenitor cells exhibited substantially increased levels of Notch, Notch intracellular domain (NICD), and hairy enhancer of split (Hes) 1, which was associated with a significant increase of proliferating cells. Blockage of the Notch pathway by short interfering ribonucleic acid (siRNA) against Notch or a gamma secretase inhibitor significantly reduced Notch, NICD and Hes1 expression and cell proliferation induced by stroke. During differentiation of neural progenitor cells, Notch and Hes1 expression was downregulated in ischemic neural progenitor cells, which was coincident with a significant increase of neuronal population. Inhibition of the Notch pathway with a gamma secretase inhibitor further substantially increased neurons, but did not alter astrocyte population in ischemic neural progenitor cells. These data suggest that the Notch signaling pathway mediates adult SVZ neural progenitor cell proliferation and differentiation after stroke.

Human umbilical cord blood serum in culture medium on oocyte maturation In vitro

In vitro maturation (IVM) of immature oocytes for infertile patients is an attractive treatment. It can avoid side effects of ovarian stimulation with gonadotropins. However, at the present the successful results of IVM treatment are lower than conventional in vitro fertilization (IVF) treatment. The key issue may be the IVM medium for immature oocyte maturation. In the present study, we compared 20% (v/v) human follicular fluid (hFF) and 20% (v/v) human umbilical cord serum (hUS) as a supplement to IVM medium. A total of 47 patients with polycystic ovary syndrome (PCOS) underwent 47 IVM treatment cycles. Immature oocytes (349) collected from 32 patients were cultured in IVM medium supplemented with hFF, and immature oocytes (160) collected from 15 patients were culture in IVM medium supplemented with hUS. The results indicate that the final maturation rate of oocytes cultured in IVM medium supplemented with hUS (93.8%) is significantly higher than those cultured in IVM medium supplemented with hFF (77.1%). The percentage of high-quality embryos produced from IVM medium supplemented with hUS (50.0%) is significantly higher than IVM medium supplemented with hFF (23.8%). In addition, the results also indicate that the final maturation rate of oocytes is higher in IVM medium supplemented with hUS and the time course of oocyte maturation is hastened. Following transfer 6 out of 15 patients (40.0%) become pregnant when IVM medium was supplemented with hUS, and 7 out of 31 patients (22.6%) were pregnant when IVM medium was supplemented with hFF. These results suggest that IVM medium containing hUS appears to be a more effective means to stimulate in vitro oocyte maturation and is capable of achieving a promising clinical outcome.

Post-ischemic treatment with erythropoietin or carbamylated erythropoietin reduces infarction and improves neurological outcome in a rat model of focal cerebral ischemia

BACKGROUND AND PURPOSE

Recombinant human erythropoietin (rhEPO; Epoetin-alpha; PROCRITtrade mark) has been shown to exert neuroprotective and restorative effects in a variety of CNS injury models. However, limited information is available regarding the dose levels required for these beneficial effects or the neuronal responses that may underlie them. Here we have investigated the dose-response to rhEPO and compared the effects of rhEPO with those of carbamylated rhEPO (CEPO) in a model of cerebral stroke in rats.

EXPERIMENTAL APPROACH

Rats subjected to embolic middle cerebral artery occlusion (MCAo) were treated with rhEPO or CEPO, starting at 6 h and repeated at 24 and 48 h, after MCAo. Cerebral infarct volumes were assessed at 28 days and neurological impairment at 7, 14, 21 and 28 days, post-MCAo.

KEY RESULTS

rhEPO at dose levels of 500, 1150 or 5000 IU kg(-1) or CEPO at a dose level of 50 microg kg(-1) significantly reduced cortical infarct volume and reduced neurologic impairment. All doses of rhEPO, but not CEPO, produced a transient increase in haematocrit, while rhEPO and CEPO substantially reduced the number of apoptotic cells and activated microglia in the ischemic boundary region.

CONCLUSIONS AND IMPLICATIONS

These data indicate that rhEPO and CEPO have anti-inflammatory and anti-apoptotic effects, even with administration at 6 h following embolic MCAo in rats. Taken together, these actions of rhEPO and CEPO are likely to contribute to their reduction of neurologic impairment following cerebral ischemia.

Real-time detection of dental calculus by blue-LED-induced fluorescence spectroscopy

Successful periodontal therapy requires sensitive techniques to discriminate dental calculus from healthy teeth. The aim of the present study was to develop a fluorescence-based procedure to enable real-time detection and quantification of dental calculus. Thirty human teeth--15 teeth with sub- and supragingival calculus and 15 healthy teeth--covered with a layer of physiological saline solution or blood were illuminated by a focused blue LED light source of 405 nm. Autofluorescence spectra recorded along a randomly selected line stretching over the crown-neck-root area of each tooth were utilized to evaluate a so called calculus parameter R, which was selected to define a relationship between the integrated intensities specific for healthy teeth and for calculus in the 477-497 nm (S(A)) and 628-685 nm (S(B)) wavelength regions, respectively. Statistical analysis was performed and a cut-off threshold of R=0.2 was found to distinguish dental calculus from healthy teeth with 100% sensitivity and specificity under various experimental conditions. The results of the spectral evaluation were confirmed by clinical and histological findings. Automated real-time detection and diagnostics for clinical use were implemented by a corresponding software program written in Visual Basic language. The method enables cost-effective and reliable calculus detection, and can be further developed for imaging applications.

Multiple factor analysis of metachronous upper urinary tract transitional cell carcinoma after radical cystectomy

Transitional cell carcinoma (TCC) of the urothelium is often multifocal and subsequent tumors may occur anywhere in the urinary tract after the treatment of a primary carcinoma. Patients initially presenting a bladder cancer are at significant risk of developing metachronous tumors in the upper urinary tract (UUT). We evaluated the prognostic factors of primary invasive bladder cancer that may predict a metachronous UUT TCC after radical cystectomy. The records of 476 patients who underwent radical cystectomy for primary invasive bladder TCC from 1989 to 2001 were reviewed retrospectively. The prognostic factors of UUT TCC were determined by multivariate analysis using the COX proportional hazards regression model. Kaplan-Meier analysis was also used to assess the variable incidence of UUT TCC according to different risk factors. Twenty-two patients (4.6%). developed metachronous UUT TCC. Multiplicity, prostatic urethral involvement by the bladder cancer and the associated carcinoma in situ (CIS) were significant and independent factors affecting the occurrence of metachronous UUT TCC (P = 0.0425, 0.0082, and 0.0006, respectively). These results were supported, to some extent, by analysis of the UUT TCC disease-free rate by the Kaplan-Meier method, whereby patients with prostatic urethral involvement or with associated CIS demonstrated a significantly lower metachronous UUT TCC disease-free rate than patients without prostatic urethral involvement or without associated CIS (log-rank test, P = 0.0116 and 0.0075, respectively). Multiple tumors, prostatic urethral involvement and associated CIS were risk factors for metachronous UUT TCC, a conclusion that may be useful for designing follow-up strategies for primary invasive bladder cancer after radical cystectomy.

Activation of immune and inflammatory systems in chronic heart failure: novel therapeutic approaches

Despite extensive research and novel treatments, chronic heart failure (CHF) remains a cause of high morbidity and mortality. Mounting evidence suggested that immune activation and inflammation play critical roles in the pathogenesis of CHF. In this review, we examine the current evidence regarding this contemporary pathophysiological mechanism, and evaluate the effects of conventional and novel cardiovascular drugs, such as calcium sensitisers and statins, on the immune and inflammatory mediator's network. Although therapies, which specifically antagonise tumour necrosis factor-alpha have not demonstrated considerable benefit in patients with CHF, there is an increasing evidence to suggest greater value from non-specific anti-inflammatory approaches, including: pentoxifylline, intravenous immunoglobulin, immune modulation therapy, growth hormones, physical training and nutrition regulation. Several innovative therapeutic targets, such as peroxisome proliferator-activated receptor gamma activators, Rho-kinase, p38 mitogen-activated protein kinase, nuclear transcription factor NF-kappaB, recovering or augmenting parasympathetic tone, cardiac resynchronisation therapy, macrophage inhibitors and chemokine receptor antagonists, are briefly discussed in this review. While we have recently demonstrated the potential merits of combining low-dose methotrexate with conventional therapy, through extensively modulating the activated immune and inflammatory mediator's network, there is a need for further rigorous research of this complex network, especially involving current promising therapies which modulate this system. Such evidence has the potential to revolutionise changes for the management of this disorder. Based on the 'heterogeneity' of immune activation and inflammation among different CHF populations, an 'optimised combination treatment' may offer exciting benefits for individual therapy in the future.

Ultraviolet upconversion fluorescence in rare-earth-ion-doped Y2O3 induced by infrared diode laser excitation

Room-temperature ultraviolet emission of Tm(3+) ions at 298 ((1)I(6)-->(3)H(6)), 364 ((1)D(2)-->(3)H(6)), and 391 nm ((1)I(6)-->(3)H(5)) was obtained in Y(2)O(3):Yb(3+)-Tm(3+) by continuous-wave diode laser excitation of 980 nm. Power dependence analysis demonstrates that five- and six-photon upconversion processes populate the (1)D(2) and (1)I(6) states, respectively. We believe that the (1)D(2) population originates from the cross relaxation (1)G(4)+(3)F(4)-->(3)H(4)+(1)D(2) of the Tm(3+) ions, while subsequent energy transfer from Yb(3+) to Tm(3+) excites the (1)D(2) state to the upper (1)I(6) state. High multiphoton-induced ultraviolet emission is also expected for other trivalent rare-earth ions similar to Tm(3+).

Molecular mapping of two cultivar-specific avirulence genes in the rice blast fungus Magnaporthe grisea

Rice blast, caused by the fungus Magnaporthe grisea, is a globally important disease of rice that causes annual yield losses. The segregation of genes controlling the virulence of M. grisea on rice was studied to establish the genetic basis of cultivar specificity in the interaction of rice and M. grisea. The segregation of avirulence and virulence was studied in 87 M. grisea F(1) progeny isolates from a cross of two isolates, Guy11 and JS153, using resistance-gene-differential rice cultivars. The segregation ratio indicated that avirulence and virulence in the rice cultivars Aichi-asahi and K59, respectively, are controlled by single major genes. Genetic analyses of backcrosses and full-sib crosses in these populations were also performed. The chi(2 )test of goodness-of-fitness for a 1:1 ratio indicated that one dominant gene controls avirulence in Aichi-asahi and K59 in this population. Based on the resistance reactions of rice differential lines harboring known resistance genes to the parental isolates, two genetically independent avirulence genes, AVR-Pit and AVR-Pia, were identified. Genetic linkage analysis showed that the SSR marker m355-356 is closely linked to AVR-Pit, on the telomere of chromosome 1 at a distance of approximately 2.3 cM. The RAPD marker S487, which was converted to a sequence-characterized amplified region (SCAR) marker, was found to be closely linked to AVR-Pia, on the chromosome 7 telomere at a distance of 3.5 cM. These molecular markers will facilitate the positional cloning of the two AVR genes, and can be applied to molecular-marker-assisted studies of M. grisea populations.

Semi-automated brain tumor and edema segmentation using MRI

PURPOSE

Manual segmentation of brain tumors from magnetic resonance images is a challenging and time-consuming task. A semi-automated method has been developed for brain tumor and edema segmentation that will provide objective, reproducible segmentations that are close to the manual results. Additionally, the method segments non-enhancing brain tumor and edema from healthy tissues in magnetic resonance images.

METHODS AND MATERIALS

In this study, a semi-automated method was developed for brain tumor and edema segmentation and volume measurement using magnetic resonance imaging (MRI). Some novel algorithms for tumor segmentation from MRI were integrated in this medical diagnosis system. We exploit a hybrid level set (HLS) segmentation method driven by region and boundary information simultaneously, region information serves as a propagation force which is robust and boundary information serves as a stopping functional which is accurate. Ten different patients with brain tumors of different size, shape and location were selected, a total of 246 axial tumor-containing slices obtained from 10 patients were used to evaluate the effectiveness of segmentation methods.

RESULTS

This method was applied to 10 non-enhancing brain tumors and satisfactory results were achieved. Two quantitative measures for tumor segmentation quality estimation, namely, correspondence ratio (CR) and percent matching (PM), were performed. For the segmentation of brain tumor, the volume total PM varies from 79.12 to 93.25% with the mean of 85.67+/-4.38% while the volume total CR varies from 0.74 to 0.91 with the mean of 0.84+/-0.07. For the segmentation of edema, the volume total PM varies from 72.86 to 87.29% with the mean of 79.54+/-4.18% while the volume total CR varies from 0.69 to 0.85 with the mean of 0.79+/-0.08. The HLS segmentation method perform better than the classical level sets (LS) segmentation method in PM and CR.

CONCLUSIONS

The results of this research may have potential applications, both as a staging procedure and a method of evaluating tumor response during treatment, this method can be used as a clinical image analysis tool for doctors or radiologists.

Reconstruction of maxillectomy defect by transport distraction osteogenesis

The study aimed to explore the feasibility of posterior maxillectomy reconstruction by transport distraction in a primate model. In each of 14 male adult rhesus monkeys, posterior partial maxillectomy was performed on one side of maxilla to create a posterior maxillary deflect. Immediately after the maxillectomy, a dentoalveolar segment anterior to the defect was osteotomized as transport segment and a custom-made transport distractor was fixed on the residual maxilla. After a latency period of 5 days, the distractor was activated 1 mm daily to move the transport segment backward to the defect. This process lasted about 2 weeks. The transport segment was allowed to consolidate and the animals were sacrificed at different defined intervals. Transport distraction was successful in six animals. Three other cases were completed with minor wound dehiscence and one had a small oro-antral fistula with subsequent maxillary sinusitis. New bone bridging the distraction gap was confirmed by radiography and histology in the animals completing distraction. Reconstruction of posterior maxillectomy defect is proven feasible by transport distraction osteogenesis.

Kinetics of beta-mannanase fermentation by Bacillus licheniformis

Bacterial growth, konjac powder utilization and beta-mannanase production by Bacillus licheniformis NK-27 in batch fermentation were used to develop a model of the process. The optimal set of parameters was estimated by fitting the model to experimental data. The results predicted by the model were in good agreement with the experimental data.

NOMENCLATURE

fs, fraction parameter; Kp, constant in Equation (6) (g l(-1)); Ks, Monod constant for bacteria growth (g l(-1)); m, maintenance coefficient (g g(-1) h(-1)); P, beta-mannanase concentration (g 1(-1)); qm, constant in Equation (6) (h(-1)); S, substrate concentration (g l(-1)); S0, initial substrate concentration (g l(-1)); Si, insoluble substrate concentration (g l(-1)); Ss, soluble substrate concentration (g l(-1)); t, fermentation time (h); tL, lag time (h); mu, specific growth rate (h(-1)); mu(max), maximum specific growth rate (h(-1)); X, biomass concentration (g l(-1)); YP/S, beta-mannanase yield on carbon substrate (g g(-1)); YX/S, biomass yield on carbon substrate (g g(-1)).

Migration and differentiation of adult rat subventricular zone progenitor cells transplanted into the adult rat striatum

Adult brain subventricular zone progenitor cells undergo neurogenesis in the olfactory bulb. We tested the hypothesis that cultured adult subventricular zone progenitor cells migrate and differentiate into neurons when transplanted into the adult striatum. Cells in the adult rat subventricular zone were isolated and cultured for 8 days in medium containing basic fibroblast growth factor. These cells proliferated as assayed by bromodeoxyuridine immunostaining, and the majority of them were neuron-specific class III beta-tubulin (TuJ1) immunoreactive at 8 days of culture. These cultured cells were labeled in vitro with bromodeoxyuridine or with lipophilic dye-coated particles and were transplanted into the adult rat striatum. Twenty-eight days after transplantation, the cells migrated 0.5-1.5 mm from the midline of the graft to the surrounding host striatum. Migration of grafted cells in the host striatum was also detected on magnetic resonance imaging in living rats. Morphological analysis revealed that many of these migrated cells exhibited multibranched processes from the cell soma resembling host medium-size striatal projection neurons. Only a few astrocyte-like cells were detected. Double immunostaining showed that many bromodeoxyuridine immunoreactive cells were microtubule-associated protein 2 or immunoreactive with a mouse monoclonal antibody against neuronal nuclear protein, whereas only a few bromodeoxyuridine immunoreactive cells had glial fibrillary acidic protein immunoreactivity. Morphology of bromodeoxyuridine and microtubule-associated protein 2 immunoreactive cells was similar to those of host microtubule-associated protein 2 immunoreactive cells. These results suggest that transplanted cultured adult subventricular zone progenitor cells can migrate and differentiate in response to guidance cues within the adult striatum.

[Effect of fasting on gastric mucosa thickness: experimental study in laboratory rats]

BACKGROUND

It has been proven that damage to the gastric mucosa is the result of the combined effects of acidopeptic agents including infection with Helicobacter pylori and insufficient protective mechanisms of the mucosa. Thickness of gastric mucus is very important protective factor. We can hypothetically expect that fasting may cause changes in the thickness of gastric mucus layer, which may in certain circumstances contribute to the conditions for mucosal injury. We have therefore conducted an experimental study on laboratory rats, aiming to assess the changes in the thickness of gastric mucus after 8 and 24-hour periods of fasting.

METHODS AND RESULTS

We measured gastric mucus thickness with the aid of microelectrodes in 279 laboratory rats (group I) after 8 hours of fasting (2 measurements each, total of 558 measurements), followed by the same measurement in 70 laboratory rats (group II) after a 24-hour fasting. Group I had a gastric mucus thickness of 595 +/- 10 (mean +/- SD, microns); in group II the thickness was 502 +/- 10 (mean +/- SD, microns). After statistical analysis of the homogeneity of the two populations (Fisher's analysis), it has been proven that both groups belong to the same basic population sample. The statistical evaluation of the thickness of gastric mucus in both groups showed thinning of the mucus layer to 1% of the significant statistical difference. The difference between both groups is statistically significant.

CONCLUSIONS

The thickness of gastric mucus is reduced after 24 hours' fasting in laboratory rats. This change is statistically significant (P < 0.01). It can be hypothesized that--under the specific conditions--this process can facilitate the injury of gastric mucosa.

Angiopoietin-1 reduces cerebral blood vessel leakage and ischemic lesion volume after focal cerebral embolic ischemia in mice

Angiopoietin-1 (Ang1) is a ligand for the endothelial specific receptor tyrosine kinase, Tie2, that protects the adult peripheral vasculature from vascular leakage. We tested the hypothesis that increases in levels of Ang1 reduce blood-brain barrier (BBB) leakage in ischemic brain. Mice were subjected to embolic middle cerebral artery (MCA) occlusion. Recombinant adenoviruses expressing Ang1 (Ad-Ang1) or a control gene encoding green fluorescent protein (Ad-GFP), or recombinant Ang1 protein, BowAng1, was administered to mice before MCA occlusion. Regional cerebral blood flow (rCBF), the brain tissue content of Evans Blue, and ischemic lesion volume were measured. Serum levels of Ang1 (183+/-31.9 microg/ml, n=4) were detected in mice receiving Ad-Ang1 or in mice treated with BowAng1 (262+/-35.4 microg/ml, n=7) but not in the control mice (n=11). Six hours after MCA occlusion, mice receiving Ad-GFP (n=8) or control protein (n=7) showed large Evans Blue leakage in the ipsilateral hemisphere (0.46+/-0.05 or 0.55+/-0.16 ng/mg tissue) whereas mice receiving Ad-Ang1 (n=6) or BowAng1 (n=7) had significantly (P<0.05) less Evans Blue leakage (0.26+/-0.07 or 0.14+/-0.03 ng/mg tissue). Infusion of recombinant human vascular endothelial growth factor (rhVEGF(165)) to ischemic mice resulted in significant (P<0.05) increases in Evans Blue leakage (1.24+/-0.34 ng/mg tissue, n=7) compared with the control mice. In contrast, infusion of rhVEGF(165) in ischemic mice receiving Ad-Ang1 did not significantly increase Evans Blue dye in the ipsilateral hemisphere (0.22+/-0.06 ng/mg tissue, n=6). Moreover, 24 h after ischemia mice receiving Ad-Ang1 had a significantly smaller ischemic lesion volume (22.6+/-2.7%, n=8) than the lesion volume in mice receiving Ad-GFP (44.7+/-3.7%, n=8), although rCBF reduced to approximately 20% of the contralateral levels in both groups of mice 10 min after ischemia. Our data demonstrate that Ang1 reduces BBB leakage in ischemic brain and consequently decreases ischemic lesion volume.

Time-resolved laser spectroscopy of multiply ionized atoms: natural radiative lifetimes in Ce IV

Radiative lifetimes have been measured for two excited levels of Ce IV using the time-resolved laser-induced fluorescence technique. Ce3+ ions were produced in a laser-induced plasma. In the measurements, a suitable magnetic field was applied to reduce the recombination between electrons and the ions and thus the background light from the recombination, and special care was exercised to avoid flight-out-of-view effects on the lifetime measurements for the high-velocity ions. The experimental lifetime results, tau = 30(2) ns for the level 49 737 cm(-1) and tau = 30(3) ns for the level 52 226 cm(-1), were compared with relativistic Hartree-Fock calculations (tau = 30.5 and 30.0 ns) indicating a particularly excellent agreement.

Postischemic (6-Hour) treatment with recombinant human tissue plasminogen activator and proteasome inhibitor PS-519 reduces infarction in a rat model of embolic focal cerebral ischemia

BACKGROUND AND PURPOSE

The proteasome inhibitor PS-519 blocks activation of nuclear factor-kappaB, a major mediator of inflammation. We tested the hypothesis that combination treatment of recombinant human tissue plasminogen activator (rhtPA) and PS-519 extends the therapeutic window for treatment of stroke with rhtPA without increasing incidence of hemorrhagic transformation.

METHODS

The middle cerebral artery (MCA) of male Wistar rats (n=56) was occluded by an embolus. After embolization, animals were randomly divided into the following groups: PS-519 treatment groups: PS-519 was given at 2, 4, or 6 hours after MCA occlusion; rhtPA treatment groups: rhtPA was given at 2 or 4 hours after MCA occlusion; combination treatment groups: PS-519 and rhtPA were given at 2, 4, or 6 hours after MCA occlusion; control group: the same volume of saline was given at 2 hours after MCA occlusion.

RESULTS

Administration of PS-519 alone at 2 or 4 hours, but not 6 hours, significantly (P<0.05) reduced infarct volume and improved neurological recovery compared with the control group. Administration of rhtPA alone at 2 hours, but not 4 hours, significantly (P<0.05) reduced infarct volume and improved neurological recovery compared with the control group. Furthermore, combination treatment with rhtPA and PS-519 even at 6 hours significantly (P<0.05) reduced infarct volume, improved neurological recovery, and did not increase the incidence of hemorrhagic transformation compared with the control group or the group treated with PS-519 alone.

CONCLUSIONS

Our data suggest that combination treatment with PS-519 and rhtPA extends the neuroprotective effect to at least 6 hours after embolization.

Extension of the therapeutic window for recombinant tissue plasminogen activator with argatroban in a rat model of embolic stroke

BACKGROUND AND PURPOSE

Argatroban, a specific thrombin inhibitor, has been shown to reduce ischemic lesion size after focal cerebral ischemia in rats. In addition, recombinant tissue plasminogen activator (rtPA) has been shown to reduce ischemic lesion size in both rats and humans if given within 3 hours of symptom onset. We tested the hypothesis that the administration of argatroban with rtPA could extend the treatment window of stroke to 4 hours without increasing gross cerebral hemorrhage rates or reducing efficacy.

METHODS

Male Wistar rats were subjected to middle cerebral artery (MCA) occlusion by a single fibrin-rich clot. After embolization, rats were administered argatroban at the following dose levels: 2.08, 6.25, and 18.75 microgram . kg(-1). min(-1). In a second experiment, rats received argatroban (6.25 microgram . kg(-1). min(-1)) or argatroban in combination with rtPA 4 hours after MCA occlusion. Tissue sections were then analyzed for lesion volume, gross hemorrhage and fibrin deposition.

RESULTS

The 6.25 microgram. kg(-1). min(-1) dose demonstrated a significant reduction (P<0.05) in lesion volume after 48 hours (27.2+/-6.3%) compared with controls (35.3+/-3.7%). A significant reduction (P<0.05) in lesion volume was observed in the argatroban-plus-rtPA group (17.1+/-10.4%) compared with controls (35.3+/-3.7%). No increase in hemorrhagic transformation was observed. Fibrin deposition in the ipsilateral cortical microvasculature was significantly decreased in the 4-hour combination argatroban-plus-rtPA group compared with the controls (P<0.05).

CONCLUSIONS

This study demonstrates that the combination of argatroban and rtPA extends the window of opportunity for treatment of stroke to 4 hours without increasing hemorrhagic transformation.