Tumor Volume Estimation and Quasi- Continuous Administration for Most Effective Bevacizumab Therapy

Bevacizumab is an exogenous inhibitor which inhibits the biological activity of human VEGF. Several studies have investigated the effectiveness of bevacizumab therapy according to different cancer types but these days there is an intense debate on its utility. We have investigated different methods to find the best tumor volume estimation since it creates the possibility for precise and effective drug administration with a much lower dose than in the protocol.We have examined C38 mouse colon adenocarcinoma and HT-29 human colorectal adenocarcinoma. In both cases, three groups were compared in the experiments. The first group did not receive therapy, the second group received one 200 μg bevacizumab dose for a treatment period (protocol-based therapy), and the third group received 1.1 μg bevacizumab every day (quasi-continuous therapy). Tumor volume measurement was performed by digital caliper and small animal MRI. The mathematical relationship between MRI-measured tumor volume and mass was investigated to estimate accurate tumor volume using caliper-measured data. A two-dimensional mathematical model was applied for tumor volume evaluation, and tumor- and therapy-specific constants were calculated for the three different groups. The effectiveness of bevacizumab administration was examined by statistical analysis.In the case of C38 adenocarcinoma, protocol-based treatment did not result in significantly smaller tumor volume compared to the no treatment group; however, there was a significant difference between untreated mice and mice who received quasi-continuous therapy (p = 0.002). In the case of HT-29 adenocarcinoma, the daily treatment with one-twelfth total dose resulted in significantly smaller tumors than the protocol-based treatment (p = 0.038). When the tumor has a symmetrical, solid closed shape (typically without treatment), volume can be evaluated accurately from caliper-measured data with the applied two-dimensional mathematical model.Our results provide a theoretical background for a much more effective bevacizumab treatment using optimized administration

Ghrelin Modulates the fMRI BOLD Response of Homeostatic and Hedonic Brain Centers Regulating Energy Balance in the Rat

The orexigenic gut-brain peptide, ghrelin and its G-protein coupled receptor, the growth hormone secretagogue receptor 1a (GHS-R1A) are pivotal regulators of hypothalamic feeding centers and reward processing neuronal circuits of the brain. These systems operate in a cooperative manner and receive a wide array of neuronal hormone/transmitter messages and metabolic signals. Functional magnetic resonance imaging was employed in the current study to map BOLD responses to ghrelin in different brain regions with special reference on homeostatic and hedonic regulatory centers of energy balance. Experimental groups involved male, ovariectomized female and ovariectomized estradiol-replaced rats. Putative modulation of ghrelin signaling by endocannabinoids was also studied. Ghrelin-evoked effects were calculated as mean of the BOLD responses 30 minutes after administration. In the male rat, ghrelin evoked a slowly decreasing BOLD response in all studied regions of interest (ROI) within the limbic system. This effect was antagonized by pretreatment with GHS-R1A antagonist JMV2959. The comparison of ghrelin effects in the presence or absence of JMV2959 in individual ROIs revealed significant changes in the prefrontal cortex, nucleus accumbens of the telencephalon, and also within hypothalamic centers like the lateral hypothalamus, ventromedial nucleus, paraventricular nucleus and suprachiasmatic nucleus. In the female rat, the ghrelin effects were almost identical to those observed in males. Ovariectomy and chronic estradiol replacement had no effect on the BOLD response. Inhibition of the endocannabinoid signaling by rimonabant significantly attenuated the response of the nucleus accumbens and septum. In summary, ghrelin can modulate hypothalamic and mesolimbic structures controlling energy balance in both sexes. The endocannabinoid signaling system contributes to the manifestation of ghrelin’s BOLD effect in a region specific manner. In females, the estradiol milieu does not influence the BOLD response to ghrelin

Central sensitization-related changes of effective and functional connectivity in the rat inflammatory trigeminal pain model

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Purkinje cell number-correlated cerebrocerebellar circuit anomaly in the valproate model of autism

While cerebellar alterations may play a crucial role in the development of core autism spectrum disorder (ASD) symptoms, their pathophysiology on the function of cerebrocerebellar circuit loops is largely unknown. We combined multimodal MRI (9.4 T) brain assessment of the prenatal rat valproate (VPA) model and correlated immunohistological analysis of the cerebellar Purkinje cell number to address this question. We hypothesized that a suitable functional MRI (fMRI) paradigm might show some altered activity related to disrupted cerebrocerebellar information processing. Two doses of maternal VPA (400 and 600 mg/kg, s.c.) were used. The higher VPA dose induced 3% smaller whole brain volume, the lower dose induced 2% smaller whole brain volume and additionally a focal gray matter density decrease in the cerebellum and brainstem. Increased cortical BOLD responses to whisker stimulation were detected in both VPA groups, but it was more pronounced and extended to cerebellar regions in the 400 mg/kg VPA group. Immunohistological analysis revealed a decreased number of Purkinje cells in both VPA groups. In a detailed analysis, we revealed that the Purkinje cell number interacts with the cerebral BOLD response distinctively in the two VPA groups that highlights atypical function of the cerebrocerebellar circuit loops with potential translational value as an ASD biomarker

Mean of time response curves of ghrelin's effect on the BOLD responses in the prefrontal cortex (A), nucleus accumbens (B), ventromedial nucleus (C) and paraventricular nucleus (D), in males (blue), ovariectomized females (orange) and ovariectomized females treated with E2 (green).

<p>Arrows mark ghrelin administration, which started at BOLD response 333 and lasted to 383 (999–1149 s). For quantifying drug effect mean of the BOLD responses from 901 to 950 was calculated (2703–2850 s). N = 11–14.</p

Evaluation of Phase I tumor volume values.

<p>“Measured data” is the MRI-measured tumor volume—tumor mass pairs on the 23rd day of Phase III/3 (case and control group). For this dataset, linear curve fitting was carried out (“fitted linear curve”) to find the mathematical relationship between MRI-measured tumor volume and tumor mass. Substituting tumor mass values which were measured on the 24th day of Phase I to the equation of the resulted curve, the corresponding tumor volume values can be evaluated (“evaluated data”).</p

Effect of ghrelin on BOLD responses in reward processing centers, hypothalamic nuclei and brainstem areas.

<p>Effect of ghrelin on the BOLD responses was represented by the blue columns after vehicle pretreatment, and red columns after rimonabant pretreatment. Statistically significant differences were found in the nucleus accumbens and septum. ANOVA and Fisher <i>post hoc</i> test. *: p<0.05. N = 5–7.</p

Experimental data of C38 mouse colon adenocarcinoma (tumor length, tumor width, tumor mass and tumor volume).

<p>Data was measured at the final day of Phase I (24th day) and Phase III/3 (23rd day).</p><p>^a Directly measured data (tumor length, tumor width, tumor mass)</p><p>^b Estimated data (tumor volume measured by caliper, calculated according to Xenograft tumor model protocol or two-dimensional mathematical model)</p><p>^c MRI-measured data (tumor volume calculated with flood fill algorithm)</p><p>^d Evaluated data (“MRI” tumor volume calculated from linear curve fit (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0142190#pone.0142190.e008" target="_blank">Eq 8</a>))</p><p>Experimental data of C38 mouse colon adenocarcinoma (tumor length, tumor width, tumor mass and tumor volume).</p

Overview of Phase I and Phase III/3.

<p>In Phase I, tumor growth was investigated without antiangiogenic therapy for 24 days (mice were sacrificed when the tumor reached a lethal size). In Phase III/3, control group members received one 200 <i>μg</i> bevacizumab dose for an 18-day therapy (on the 3rd and 21st days); case group members received 1.11 <i>μg</i> bevacizumab every day for 20 days.</p

Mean of time response curves of ghrelin's effect on BOLD responses in the nucleus accumbens (A) and septum (B) after vehiculum (blue) or rimonabant pretreatment (red).

<p>Arrows mark ghrelin administration, which started at BOLD response 333 and lasted to 383 (999–1149 s). For quantifying drug effect, mean of the BOLD responses from 901 to 950 was calculated (2703–2850 s). N = 5–7.</p