Live Eikenes

Collagenase Increases the Transcapillary Pressure Gradient and Improves the Uptake and Distribution of Monoclonal Antibodies in Human Osteosarcoma Xenografts

Cancer therapy based on tumor-selective macromolecules may fail due to the elevated interstitial fluid pressure (IFP) that reduces the transvascular and interstitial convection in solid tumors. Modulation of the tumor extracellular matrix (ECM) may reduce IFP and enhance transvascular filtration and interstitial transport of macromolecules. We therefore measured the effect of the ECM-degrading enzyme collagenase on IFP and microvascular pressure (MVP) in human osteosarcoma xenografts using the wick-in-needle and micropipette methods, respectively. The tumor uptake and distribution of a systemically administered osteosarcoma-associated monoclonal antibody (TP-3) after i.v. injection of collagenase were analyzed using confocal laser scanning microscopy. Collagenase (0.1%) reduced both IFP (45%) and MVP (60%), but the kinetics of the recoveries differed, because MVP had recovered by the time IFP reached its minimum level. Thus, collagenase increased the transcapillary pressure gradient, inducing a 2-fold increase in the tumor uptake and improving the distribution of the monoclonal antibody, which was localized further into the tumor. To study the mechanism of the reduction in MVP, mean arterial blood pressure was measured and found not to be affected by the collagenase treatment. The reduction in MVP was rather due to reduced vascular resistance because microvascular-associated collagen was totally or partially disintegrated. Although collagenase may favor metastasis and thus not be clinically relevant, this study shows proof of principle that degradation of the ECM leads to a favorable change in the transvascular pressure gradient, thereby increasing antibody penetration and binding to tumor cells.

Hyaluronidase induces a transcapillary pressure gradient and improves the distribution and uptake of liposomal doxorubicin (Caelyx) in human osteosarcoma xenografts.

Liposomal drug delivery enhances the tumour selective localisation and may improve the uptake compared to free drug. However, the drug distribution within the tumour tissue may still be heterogeneous. Degradation of the extracellular matrix is assumed to improve the uptake and penetration of drugs. The effect of the ECM-degrading enzyme hyaluronidase on interstitial fluid pressure and microvascular pressure were measured in human osteosarcoma xenografts by the wick-in-needle and micropipette technique, respectively. The tumour uptake and distribution of liposomal doxorubicin were studied on tumour sections by confocal laser scanning microscopy. The drugs were injected i.v. 1 h after the hyaluronidase pretreatment. Intratumoral injection of hyaluronidase reduced interstitial fluid pressure in a nonlinear dose-dependent manner. Maximum interstitial fluid pressure reduction of approximately 50% was found after injection of 1500 U hyaluronidase. Neither intratumoral nor i.v. injection of hyaluronidase induced any changes in the microvascular pressure. Thus, hyaluronidase induced a transcapillary pressure gradient, resulting in a four-fold increase in the tumour uptake and improving the distribution of the liposomal doxorubicin. Hyaluronidase reduces a major barrier for drug delivery by inducing a transcapillary pressure gradient, and administration of hyaluronidase adjuvant with liposomal doxorubicin may thus improve the therapeutic outcome.

Young adults born preterm with very low birth weight demonstrate widespread white matter alterations on brain DTI

Preterm birth with very low birth weight (VLBW, ≤1500 g) is connected to reduced white matter (WM) integrity in childhood and adolescence. These changes in WM are correlated to motor, sensory and neuropsychological impairments. CNS myelination continues into the early twenties, but the consequences of this for WM integrity in VLBWs have not been explored. DTI and tract based spatial statistics (TBSS) was carried out to test for voxelwise differences in fractional anisotropy (FA), eigenvalues and mean diffusivity (MD) between a preterm VLBW group (n=49) and a control group born at term (n=59) at 18-22 years of age. TBSS was also used to explore the relationship between perinatal clinical data and general cognitive ability (total IQ), respectively, and the DTI metrics (FA and MD), with gender and age as a confounder. In the VLBW group several major WM tracts particularly in the posterior region had significantly reduced FA caused by an increase in the two lowest eigenvalues. MD was significantly increased in the VLBWs in 50% of the same regions as the FA changes, but encompassing also more peripheral WM. In the VLBW group, FA was found to correlate positively with birth weight and negatively with number of days in intensive care and on mechanical ventilator, particularly in the corpus callosum. FA was found to correlate positively with total IQ in the young preterm adults. In the controls there was no correlation between FA and total IQ. Our results indicate that the neurologic sequelae of preterm birth with VLBW are a lifelong condition inducing structural and functional impairments also in adulthood in VLBW survivors. The greatest risk of having reduced WM integrity in adulthood was found in the most immature VLBW neonates requiring mechanical ventilation and long-term intensive care.

Radiation improves the distribution and uptake of liposomal doxorubicin (Caelyx) in human osteosarcoma xenografts

Liposomal drug delivery appears to improve the antitumor effect and reduce toxicity compared with the free drug. The therapeutic index may be improved further by combining cytotoxic drugs and radiotherapy. Successful therapy requires that the cytotoxic agents reach the tumor cells. Therefore, we studied tumor growth and the microdistribution of liposomal doxorubicin (Caelyx) with and without additional ionizing radiation in human osteosarcoma xenografts in athymic mice. Caelyx was injected i.v. 1 day before single or fractionated radiotherapy. Both chemoirradiation regimens induced significant tumor growth delays and worked synergistically. Confocal laser scanning microscopy showed that intact liposomes were located in close proximity to endothelial cells, and the distribution of released doxorubicin was heterogeneous. Before radiotherapy, hardly any doxorubicin was localized in the central parts of the tumor. Radiotherapy increased the tumor uptake of doxorubicin by a factor of two to four, with drug being redistributed farther from the vessels in the tumor periphery and located around vessels in the central parts of the tumor. Colocalization of doxorubicin and hypoxic cells showed no distribution of drug into hypoxic areas. Dynamic contrast-enhanced magnetic resonance imaging (MRI) 1 day before the injection of Caelyx and 2 days after treatment start showed that the combined treatment reduced the vascular volume and the vascular transfer rate of the MRI tracer. The results show that chemoirradiation with Caelyx induces synergistic treatment effects. Improved intratumoral drug uptake and distribution are responsible to some extent for the enhanced antitumor effect.

Follow-up at age 10 years in ELBW children — Functional outcome, brain morphology and results from motor assessments in infancy ☆ ☆☆

BACKGROUND Extremely-low-birth-weight (ELBW) children without severe brain injury or CP are at high risk of developing deficits within cognition, attention, behavior and motor function. Assessing the quality of an infants spontaneous motor-repertoire included in Prechtls General-Movement-Assessment (GMA) has been shown to relate to later motor and cognitive functioning in preterm children without CP. AIMS To investigate functional outcome and cerebral MRI morphometry at 10 years in ELBW children without CP compared to healthy controls and to examine any relationship with the quality of infant-motor-repertoire included in the GMA. STUDY DESIGN A cohort-study-design. SUBJECTS 31 ELBW children (mean birth-weight: 773 g, SD 146, mean gestational age 26.1 weeks, SD 1.8) and 33 term-born, age-matched controls. OUTCOME MEASURES GMA was performed in ELBW children at 3 months corrected age. At 10 years the children underwent comprehensive motor, cognitive, behavioral assessments and cerebral MRI. RESULTS The non-CP ELBW children had similar full-IQ but poorer working memory, poorer motor skills, and more attentional and behavioral problems compared to controls. On cerebral MRI reduced volumes of globus pallidus, cerebellar white matter and posterior corpus callosum were found. Cortical surface-area was reduced in temporal, parietal and anterior-medial-frontal areas. Poorer test-results and reduced brain volumes were mainly found in ELBW children with fidgety movements combined with abnormal motor-repertoire in infancy. CONCLUSION Non-CP ELBW children have poorer functional outcomes, reduced brain volumes and cortical surface-area compared with term-born controls at 10 years. ELBW children with abnormal infant motor-repertoire seem to be at increased risk of later functional deficits and brain pathology.

Visual–motor deficits relate to altered gray and white matter in young adults born preterm with very low birth weight

Individuals born preterm and at very low birth weight (birth weight ≤ 1500 g) are at an increased risk of perinatal brain injury and neurodevelopmental deficits over the long term. This study examined whether this clinical group has more problems with visual-motor integration, motor coordination, and visual perception compared to term-born controls, and related these findings to cortical surface area and thickness and white matter fractional anisotropy. Forty-seven preterm-born very low birth weight individuals and 56 term-born controls were examined at 18-22 years of age with a combined cognitive, morphometric MRI, and diffusion tensor imaging evaluation in Trondheim, Norway. Visual-motor skills were evaluated with the Beery-Buktenica Developmental Test of Visual-Motor Integration-V (VMI) copying test and its supplemental tests of motor coordination and visual perception. 3D T1-weighted MPRAGE images and diffusion tensor imaging were done at 1.5 T. Cortical reconstruction generated in FreeSurfer and voxelwise maps of fractional anisotropy calculated with Tract-Based Spatial Statistics were used to explore the relationship between MRI findings and cognitive results. Very low birth weight individuals had significantly lower scores on the copying and motor coordination tests compared with controls. In the very low birth weight group, VMI scores showed significant positive relationships with cortical surface area in widespread regions, with reductions of the superior temporal gyrus, insula, and medial occipital lobe in conjunction with the posterior ventral temporal lobe. Visual perception scores also showed positive relationships with cortical thickness in the very low birth weight group, primarily in the lateral occipito-temporo-parietal junction, the superior temporal gyrus, insula, and superior parietal regions. In the very low birth weight group, visual-motor performance correlated positively with fractional anisotropy especially in the corpus callosum, inferior fronto-occipital fasciculus bilaterally, and anterior thalamic radiation bilaterally, driven primarily by an increase in radial diffusivity. VMI scores did not demonstrate a significant relationship to cortical surface area, cortical thickness, or diffusion measures in the control group. Our results indicate that visual-motor integration problems persist into adulthood for very low birth weight individuals, which may be due to structural alterations in several specific gray-white matter networks. Visual-motor deficits appear related to reduced surface area of motor and visual cortices and disturbed connectivity in long association tracts containing visual and motor information. We conjecture that these outcomes may be due to perinatal brain injury or aberrant cortical development secondary to injury or due to very preterm birth.

White matter microstructure in chronic moderate-to-severe traumatic brain injury: Impact of acute-phase injury-related variables and associations with outcome measures

This study examines how injury mechanisms and early neuroimaging and clinical measures impact white matter (WM) fractional anisotropy (FA), mean diffusivity (MD), and tract volumes in the chronic phase of traumatic brain injury (TBI) and how WM integrity in the chronic phase is associated with different outcome measures obtained at the same time. Diffusion tensor imaging (DTI) at 3 T was acquired more than 1 year after TBI in 49 moderate‐to‐severe‐TBI survivors and 50 matched controls. DTI data were analyzed with tract‐based spatial statistics and automated tractography. Moderate‐to‐severe TBI led to widespread FA decreases, MD increases, and tract volume reductions. In severe TBI and in acceleration/deceleration injuries, a specific FA loss was detected. A particular loss of FA was also present in the thalamus and the brainstem in all grades of diffuse axonal injury. Acute‐phase Glasgow Coma Scale scores, number of microhemorrhages on T2*, lesion volume on fluid‐attenuated inversion recovery, and duration of posttraumatic amnesia were associated with more widespread FA loss and MD increases in chronic TBI. Episodes of cerebral perfusion pressure <70 mmHg were specifically associated with reduced MD. Neither episodes of intracranial pressure >20 mmHg nor acute‐phase Rotterdam CT scores were associated with WM changes. Glasgow Outcome Scale Extended scores and performance‐based cognitive control functioning were associated with FA and MD changes, but self‐reported cognitive control functioning was not. In conclusion, FA loss specifically reflects the primary injury severity and mechanism, whereas FA and MD changes are associated with objective measures of general and cognitive control functioning.

How Does the Accuracy of Intracranial Volume Measurements Affect Normalized Brain Volumes? Sample Size Estimates Based on 966 Subjects from the HUNT MRI Cohort

BACKGROUND AND PURPOSE: The intracranial volume is commonly used for correcting regional brain volume measurements for variations in head size. Accurate intracranial volume measurements are important because errors will be propagated to the corrected regional brain volume measurements, possibly leading to biased data or decreased power. Our aims were to describe a fully automatic SPM-based method for estimating the intracranial volume and to explore the practical implications of different methods for obtaining the intracranial volume and normalization methods on statistical power. MATERIALS AND METHODS: We describe a method for calculating the intracranial volume that can use either T1-weighted or both T1- and T2-weighted MR images. The accuracy of the method was compared with manual measurements and automatic estimates by FreeSurfer and SPM-based methods. Sample size calculations on intracranial volume–corrected regional brain volumes with intracranial volume estimates from FreeSurfer, SPM, and our proposed method were used to explore the benefits of accurate intracranial volume estimates. RESULTS: The proposed method for estimating the intracranial volume compared favorably with the other methods evaluated here, with mean and absolute differences in manual measurements of −0.1% and 2.2%, respectively, and an intraclass correlation coefficient of 0.97 when using T1-weighted images. Using both T1- and T2-weighted images for estimating the intracranial volume slightly improved the accuracy. Sample size calculations showed that both the accuracy of intracranial volume estimates and the method for correcting the regional volume measurements affected the sample size. CONCLUSIONS: Accurate intracranial volume estimates are most important for ratio-corrected regional brain volumes, for which our proposed method can provide increased power in intracranial volume–corrected regional brain volume data.

Being born small for gestational age reduces white matter integrity in adulthood: a prospective cohort study

Background:Being born small for gestational age (SGA) (birth weight <10th percentile) is connected to decreased white matter (WM) integrity in newborns and increased prevalence of psychiatric symptoms in adulthood. The aims of this study were to investigate whether being born SGA at term affects WM integrity in young adulthood and to explore possible relationships between fractional anisotropy (FA) and pre- and perinatal factors and cognitive and psychiatric outcomes in adulthood in SGA and controls.Methods:Diffusion tensor imaging and tract-based spatial statistics were conducted to test for voxelwise differences in FA in SGAs (n = 46) and controls (n = 57) at 18–22 y.Results:As compared with controls SGAs had reduced FA in ventral association tracts and internal/external capsules. In the SGAs, no relationship was found between FA and intrauterine head growth in the third trimester, although total intelligence quotient was negatively correlated to FA. In controls, a positive correlation was found between FA and brain growth in the third trimester and maternal smoking. No relationship was found between FA and psychiatric measures in SGAs or controls.Conclusion:These results demonstrate that being born SGA leads to reduced WM integrity in adulthood, and suggest that different factors modulate the development of WM in SGA and control groups.

Visual function and white matter microstructure in very-low-birth-weight (VLBW) adolescents - A DTI study

Premature birth is associated with visual impairments, due to both cerebral and ocular pathology. This study examined the relationship between cerebral white matter microstructure, evaluated by diffusion tensor imaging (DTI), and visual function, in 30 preterm born adolescents with very low birth weight (VLBW=birth weight⩽1500g) and an age-matched group of 45 term born controls. Visual acuity correlated positively with fractional anisotropy (FA) in corpus callosum and in frontal white matter areas in the VLBW participants, but not in the control participants. Callosal visual connections may play a more important role in the development of good visual acuity than previously acknowledged in preterm born children.