Perceptual Speed and IQ Are Associated Through Common Genetic Factors

Individual differences in inspection time explain about 20% of IQ test variance. To determine whether the association between inspection time and IQ is mediated by common genes or by a common environmental factor, inspection time and IQ were assessed in an extended twin design. Data from 688 participants from 271 families were collected as part of a large ongoing project on the genetics of adult brain function and cognition. The sample consisted of a young adult cohort (mean age 26.2 years) and an older adult cohort (mean age 50.4 years). IQ was assessed with the Dutch version of the WAIS-3R. Inspection time was measured in the so-called -paradigm, in which a subject is asked to decide which leg of the -figure is longest at varying display times of the -figure. The number of correct inspections per second (i.e., the reciprocal of inspection time) was used to index perceptual speed. For Verbal IQ and Performance IQ, heritabilities were 85% and 69%, respectively. For perceptual speed, 46% of the total variance was explained by genetic variance. No differences in heritability estimates across age cohorts or sexes were found. Across the whole sample, a significant phenotypic correlation was found between perceptual speed and Verbal IQ (0.19) and between perceptual speed and Performance IQ (0.27). These correlations were entirely due to a common genetic factor that accounted for 10% of the genetic variance in verbal IQ and for 22% of the genetic variance in performance IQ. This factor is hypothesized to reflect the influence of genetic factors that determine axonal myelination in the central nervous system.     

Utilization of cartilage graft technology for the testing of novel chondro-therapeutic agents

Introduction The aims of the current study were to (i) tissue engineer a cartilage graft with structural and biochemical properties of native articular cartilage in vivo, with potential for use in cartilage repair technologies and (ii) utilize this model as a test system to evaluate the efficiency of novel therapeutics for future research into cartilage metabolism in health and disease. Materials and methods Articular cartilage was harvested from hock joints of (young) 7‐day and (old) 18‐month bovine sources. Cells were isolated by enzymatic digestion and seeded at a range of cell densities (2, 4, 6, 8, 10 and 12 × 10⁶ cells/insert) into type II collagen‐coated Millipore filter inserts and cultured as described previously ( Kandel et al. 1995 ). In order to mimic a catabolic effect on cartilage, some samples were treated with IL‐1α (10 ng/ml) for 24 h in the absence or presence of experimental drugs. Proteoglycan (PG) release, detectable in the medium, was analysed by colorimetric assay ( Farndale et al. 1986 ). At the end of the culture period, cartilage grafts were fixed, sectioned and stained with Alcian Blue or immuno‐fluorescently labelled with a panel of monoclonal antibodies recognizing several components of the graft extracellular matrix. Results Full‐depth chondrocytes from both young and old bovine sources produced a stratified hyaline tissue with distinct zones after 2 weeks in culture. These zones approximated to the surface, middle and deep zones that characterize native articular cartilage in vivo. Increased culture time and seeding density produced cartilage of an increased thickness and cellularity, respectively. Grafts produced from young cartilage contained approximately 3 times more sulfated PG than grafts produced from an old cartilage, indicating an increased matrix secretion in these cultures. Histologically, the old grafts were also thinner and more weakly stained with Alcian Blue, indicating a lower sulfated PG content. Addition of IL‐1α to the cultures resulted in a dramatic PG release from the cartilage grafts, manifest histologically as a loss of Alcian Blue staining in the upper third of the cartilage tissue. Immunofluorescent staining identified subtle changes in matrix composition and in the structure and catabolism of matrix proteoglycans in response to both IL‐1a and the experimental drugs tested. Discussion The grafts produced had many structural and biochemical similarities to articular cartilage in vivo. These grafts may better integrate with the host cartilage in cartilage repair procedure. This culture system also provides ideal conditions to analyse the response of engineered grafts to catabolic factors that occur in the arthritic joint, along with ideal conditions for research into drug therapies. Advantages of this culture system, in comparison with an explant system, are that effects can be analysed within a 24‐h period. Future work will include applying fatty acids, modified glucosamine and some Asian herbal remedies to this culture system and analysing their potential chondroprotective effects.     

Controlled Release of Theophylline Monohydrate from Amylodextrin Tablets: In Vitro Observations

Amylodextrin is a linear dextrin and can be produced by enzymatic hydrolysis of the -1,6 glycosidic bonds of amylopectin. Tablets compacted from pure amylodextrin showed good binding properties and did not disintegrate in aqueous media. Extended and decreasing drug release rates were found for tablets of 300 mg with a diameter of 9 mm containing 70% amylodextrin and 30% theophylline monohydrate, when compacted at 5 kN. Almost-constant drug release rates were obtained for these tablets when compacted at 10 or 15 kN. Nearly constant drug release rates were also shown for amylodextrin tablets with a drug load up to 75% compacted at 10 kN. Both release rate and release profile could be adjusted by selecting tablet thickness and incorporation of either lactose as a highly soluble excipient or talc as a hydrophobic excipient.     

Significance of plasma transforming growth factor-β levels in radiotherapy for non–small-cell lung cancer

PURPOSE: In dose-escalation studies of radiotherapy (RT) for non-small-cell lung cancer (NSCLC), radiation pneumonitis (RP) is the most important dose-limiting complication. Transforming growth factor-beta1 (TGF-beta1) has been reported to be associated with the incidence of RP. It has been proposed that serial measurements of plasma TGF-beta1 can be valuable to estimate the risk of RP and to decide whether additional dose-escalation can be safely applied. The aim of this study was to evaluate prospectively the time course of TGF-beta1 levels in patients irradiated for NSCLC in relation to the development of RP and dose-volume parameters. METHODS AND MATERIALS: Plasma samples were obtained in 68 patients irradiated for medically inoperable or locally advanced NSCLC (dose range, 60.8-94.5 Gy) before and 4, 6, and 18 weeks after the start of RT. Plasma TGF-beta1 levels were determined using a bioassay on the basis of TGF-beta1-induced plasminogen activator inhibitor-1 expression in mink lung cells. All patients underwent chest computed tomography scans before RT that were repeated at 18 weeks after RT. The computed tomography data were used to calculate the mean lung dose (MLD) and to score the radiation-induced radiologic changes. RP was defined on the basis of the presence of either radiographic changes or clinical symptoms. Symptomatic RP was scored according to the Common Toxicity Criteria (Grade 1 or worse) and the Southwestern Oncology Group criteria (Grade 2 or worse). Multivariate analyses were performed to investigate which factors (pre- or posttreatment TGF-beta1 level, MLD) were associated with the incidence of RP. To improve our understanding of the time course of TGF-beta1 levels, we performed a multivariate analysis to investigate which factors (pre-RT TGF-beta1 level, MLD, RP) were independently associated with the posttreatment TGF-beta1 levels. RESULTS: The pre-RT TGF-beta1 levels were increased in patients with NSCLC (median 21 ng/mL, range, 5-103 ng/mL) compared with healthy individuals (range, 4-12 ng/mL). On average, the TGF-beta1 levels normalized toward the end of treatment and remained stable until 18 weeks after RT. In 29 patients, however, TGF-beta1 was increased at the end of RT with respect to the pre-RT value. The multivariate analyses revealed that the MLD was the only variable that correlated significantly with the risk of both radiographic RP (p = 0.05) and symptomatic RP, independent of the scoring system used (p = 0.05 and 0.03 for Southwestern Oncology Group and Common Toxicity Criteria systems, respectively). The TGF-beta1 level at the end of RT was significantly associated with the MLD (p <0.001) and pre-RT TGF-beta1 level (p = 0.001). CONCLUSION: The MLD correlated significantly with the incidence of both radiographic and symptomatic RP. The results of our study did not confirm the reports that increased levels of TGF-beta1 at the end of RT are an independent additional risk factor for developing symptomatic RP. However, the TGF-beta1 level at the end of a RT was significantly associated with the MLD and the pre-RT level.     

Incorporating an improved dose-calculation algorithm in conformal radiotherapy of lung cancer: re-evaluation of dose in normal lung tissue.

BACKGROUND AND PURPOSE: The low density of lung tissue causes a reduced attenuation of photons and an increased range of secondary electrons, which is inaccurately predicted by the algorithms incorporated in some commonly available treatment planning systems (TPSs). This study evaluates the differences in dose in normal lung tissue computed using a simple and a more correct algorithm. We also studied the consequences of these differences on the dose-effect relations for radiation-induced lung injury. MATERIALS AND METHODS: The treatment plans of 68 lung cancer patients initially produced in a TPS using a calculation model that incorporates the equivalent-path length (EPL) inhomogeneity-correction algorithm, were recalculated in a TPS with the convolution-superposition (CS) algorithm. The higher accuracy of the CS algorithm is well-established. Dose distributions in lung were compared using isodoses, dose-volume histograms (DVHs), the mean lung dose (MLD) and the percentage of lung receiving >20 Gy (V20). Published dose-effect relations for local perfusion changes and radiation pneumonitis were re-evaluated. RESULTS: Evaluation of isodoses showed a consistent overestimation of the dose at the lung/tumor boundary by the EPL algorithm of about 10%. This overprediction of dose was also reflected in a consistent shift of the EPL DVHs for the lungs towards higher doses. The MLD, as determined by the EPL and CS algorithm, differed on average by 17+/-4.5% (+/-1SD). For V20, the average difference was 12+/-5.7% (+/-1SD). For both parameters, a strong correlation was found between the EPL and CS algorithms yielding a straightforward conversion procedure. Re-evaluation of the dose-effect relations showed that lung complications occur at a 12-14% lower dose. The values of the TD(50) parameter for local perfusion reduction and radiation pneumonitis changed from 60.5 and 34.1 Gy to 51.1 and 29.2 Gy, respectively. CONCLUSIONS: A simple tissue inhomogeneity-correction algorithm like the EPL overestimates the dose to normal lung tissue. Dosimetric parameters for lung injury (e.g. MLD, V20) computed using both algorithms are strongly correlated making an easy conversion feasible. Dose-effect relations should be refitted when more accurate dose data is available.     

First results of a phase I/II dose escalation trial in non-small cell lung cancer using three-dimensional conformal radiotherapy.

PURPOSE: To evaluate the feasibility of dose escalation in non-small cell lung cancer (NSCLC) using three-dimensional conformal radiation therapy. PATIENTS AND METHODS: The main eligibility criteria of the trial were: pathologically proven inoperable NSCLC, ECOG performance status or=grade 3 (SWOG), grade 3 early and grade 2 late esophageal toxicity or any other (RTOG) grade 3 or 4 complications). RESULTS: Fifty-five patients were included. Tumor stage was I/II in 47%, IIIA in 33% and IIIB in 20%. The majority of the patients received a dose of 74.3 Gy (n=17) or 81.0 Gy (n=23). Radiation pneumonitis occurred in seven patients: four patients developed a grade 2, two patients grade 3 and one patient a grade 4. Esophageal toxicity was mild. In 50 patients tumor response at 3 months follow-up was evaluable. In six patients a complete response was recorded, in 38 a partial response, five patients had stable disease and one patient experienced progressive disease. Only one patient developed an isolated failure in an uninvolved nodal area. So far the radiation dose was safely escalated to 87.8 Gy in group 1 (lowest rMLD), 81.0 Gy in groups 2 and 3 and 74.3 Gy in group 4. CONCLUSION: Three-dimensional conformal radiotherapy enables significant dose escalation in NSCLC. The maximum tolerable dose has not yet been reached in any risk group.     

Effects of radiotherapy planning with a dedicated combined PET-CT-simulator of patients with non-small cell lung cancer on dose limiting normal tissues and radiation dose-escalation: a planning study.

BACKGROUND AND PURPOSE: To investigate the effect of radiotherapy planning with a dedicated combined PET-CT simulator of patients with locally advanced non-small cell lung cancer. PATIENTS AND METHODS: Twenty-one patients underwent a pre-treatment simulation on a dedicated hybrid PET-CT-simulator. For each patient, two 3D conformal treatment plans were made: one with a CT based PTV and one with a PET-CT based PTV, both to deliver 60Gy in 30 fractions. The maximum tolerable prescribed radiation dose for CT versus PET-CT PTV was calculated based on constraints for the lung, the oesophagus, and the spinal cord, and the Tumour Control Probability (TCP) was estimated. RESULTS: For the same toxicity levels of the lung, oesophagus and spinal cord, the dose could be increased from 55.2+/-2.0Gy with CT planning to 68.9+/-3.3Gy with the use of PET-CT (P=0.002), with corresponding TCP's of 6.3+/-1.5% for CT and 24.0+/-5.6% for PET-CT planning (P=0.01). CONCLUSIONS: The use of a combined dedicated PET-CT-simulator reduced radiation exposure of the oesophagus and the lung, and thus allowed significant radiation dose escalation whilst respecting all relevant normal tissue constraints.     

Targeting JNK-interacting protein 1 (JIP1) sensitises osteosarcoma to doxorubicin

Osteosarcoma (OS) is the most common primary malignant bone tumour in children and adolescents. Despite aggressive therapy, survival outcomes remain unsatisfactory, especially for patients with metastatic disease or patients with a poor chemotherapy response. Chemoresistance contributes to treatment failure. To increase the efficacy of conventional chemotherapy, essential survival pathways should be targeted concomitantly. Here, we performed a loss-of-function siRNA screen of the human kinome in SaOS-2 cells to identify critical survival kinases after doxorubicin treatment. Gene silencing of JNK-interacting-protein-1 (JIP1) elicited the most potent sensitisation to doxorubicin. This candidate was further explored as potential target for chemosensitisation in OS. A panel of OS cell lines and human primary osteoblasts was examined for sensitisation to doxorubicin using small molecule JIP1-inhibitor BI-78D3. JIP1 expression and JIP1-inhibitor effects on JNK-signalling were investigated by Western blot analysis. JIP1 expression in human OS tumours was assessed by immunohistochemistry on tissue micro arrays. BI-78D3 blocked JNK-signalling and sensitised three out of four tested OS cell lines, but not healthy osteoblasts, to treatment with doxorubicin. Combination treatment increased the induction of apoptosis. JIP1 was found to be expressed in two-thirds of human primary OS tissue samples. Patients with JIP1 positive tumours showed a trend to inferior overall survival. Collectively, JIP1 appears a clinically relevant novel target in OS to enhance the efficacy of doxorubicin treatment by means of RNA interference or pharmacological inhibition.     

Coupling of Metal Containing Homing Devices to Liposomes via a Maleimide Linker: Use of TCEP to Stabilize Thiol-groups without Scavenging Metals

Liposomes for drug delivery are often prepared with maleimide groups on the distal end of PEG to enable coupling of homing devices, such as antibodies, or other proteins. EDTA is used to stabilize the thiol group in the homing device for attachment to the maleimide. However, when using a homing device that contains a metal, EDTA inactivates this by scavenging of the metal. Holo-transferrin (Tf) containing two iron atoms (Fe³⁺), has a much higher affinity for the Tf receptor than apo-Tf (which does not contain any Fe³⁺). To couple Tf to a liposome, the introduction of a thiol group is necessary. During this process, by using N-succinimidyl S-acetylthioacetate (SATA), followed by 2–3 h coupling to the liposomes, Fe³⁺ is scavenged by EDTA. This causes a decreased affinity of Tf for its receptor, resulting in a decreased targeting efficiency of the liposomes.

Tris(2-carboxyethyl)phosphine (TCEP) hydrochloride is a sulfhydryl reductant that is often used in protein biochemistry. We found that TCEP (0.01 mM) does not scavenge Fe³⁺ from Tf and is able to protect thiol groups for the coupling to maleimide. Furthermore, TCEP does not interfere with the maleimide coupling itself.

In this communication, we describe the preparation of liposomes, focussing on the coupling of Tf to the maleimide linker at the distal end of PEG, without loosing Fe³⁺ from Tf. This method can be applied to other metal-containing homing devices as well.