Advantages of gadolinium based ultrasmall nanoparticles vs molecular gadolinium chelates for radiotherapy guided by MRI for glioma treatment

AGuIX nanoparticles are formed of a polysiloxane network surrounded by gadolinium chelates. They present several characteristics. They are easy to produce, they present very small hydrodynamic diameters (<5 nm) and they are biodegradable through hydrolysis of siloxane bonds. Such degradation was evaluated in diluted conditions at physiological pH by dynamic light scattering and relaxometry. AGuIX nanoparticles are also known as positive contrast agents and efficient radiosensitizers. The aim of this paper is to compare their efficiency for magnetic resonance imaging and radiosensitization to those of the commercial gadolinium based molecular agent: DOTAREM®. An experiment with healthy animals was conducted and the MRI pictures we obtained show a better contrast with the AguIX compared to the DOTAREM® for the same amount of injected gadolinium in the animal. The better contrast obtained after injection of Aguix than DOTAREM® is due to a higher longitudinal relaxivity and a residential time in the blood circulation that is two times higher. A fast and large increase in the contrast is also observed by MRI after an intravenous injection of the AGuIX in 9 L gliosarcoma bearing rats, and a plateau is reached seven minutes after the injection.

We established a radiotherapy protocol consisting of an irradiation by microbeam radiation therapy 20 minutes after the injection of a specific quantity of gadolinium. After microbeam radiation therapy, no notable difference in median survival time was observed in the presence or absence of gadolinium chelates (38 and 44 days respectively). In comparison, the median survival time is increased to 102.5 days with AGuIX particles showing their interest in this nanomedicine protocol. This remarkable radiosensitizing effect could be explained by the persistent tumor uptake of the particles, inducing a significant nanoscale dose deposition under irradiation.

Early gene expression analysis in 9L orthotopic tumor-bearing rats identifies immune modulation in molecular response to synchrotron microbeam radiation therapy

Synchrotron Microbeam Radiation Therapy (MRT) relies on the spatial fractionation of the synchrotron photon beam into parallel micro-beams applying several hundred of grays in their paths. Several works have reported the therapeutic interest of the radiotherapy modality at preclinical level, but biological mechanisms responsible for the described efficacy are not fully understood to date. The aim of this study was to identify the early transcriptomic responses of normal brain and glioma tissue in rats after MRT irradiation (400Gy). The transcriptomic analysis of similarly irradiated normal brain and tumor tissues was performed 6 hours after irradiation of 9 L orthotopically tumor-bearing rats. Pangenomic analysis revealed 1012 overexpressed and 497 repressed genes in the irradiated contralateral normal tissue and 344 induced and 210 repressed genes in tumor tissue. These genes were grouped in a total of 135 canonical pathways. More than half were common to both tissues with a predominance for immunity or inflammation (64 and 67% of genes for normal and tumor tissues, respectively). Several pathways involving HMGB1, toll-like receptors, C-type lectins and CD36 may serve as a link between biochemical changes triggered by irradiation and inflammation and immunological challenge. Most immune cell populations were involved: macrophages, dendritic cells, natural killer, T and B lymphocytes. Among them, our results highlighted the involvement of Th17 cell population, recently described in tumor. The immune response was regulated by a large network of mediators comprising growth factors, cytokines, lymphokines. In conclusion, early response to MRT is mainly based on inflammation and immunity which appear therefore as major contributors to MRT efficacy.

TheraDrive: a new stroke therapy concept for home-based, computer-assisted motivating rehabilitation

Stroke results in functional arm impairments that persist even after rehabilitation training. The increasing numbers of persons at-risk in the population for stroke creates an increased need for therapy programs that can be effectively administered in both home and outpatient clinics. The aim of this work is to create a low-cost, commercially-viable, home-based rehabilitation system that can capitalize on computer-assisted motivating rehabilitation concepts of game therapy and skill training with functional training related to real activities to induce user-dependent CNS plasticity. The TheraDrive concept combines the motivational elements of relearning steering tasks with playing driving video games using commercial force-feedback steering wheels to create an upper arm stroke therapy environment that is usable at home or in the clinic. This paper presents the concept and reports on investigations to evaluate the main commercial building blocks for the prototype: the steering wheel and driving software. Evaluation results of three force-feedback steering wheels and the driving gaming software called SmartDriver are presented. Future evaluation trials with stroke subjects will be completed.

In vivo two-photon microscopy study of short-term effects of microbeam irradiation on normal mouse brain microvasculature

PURPOSE

The purpose of this study was to assess the early effects of microbeam irradiation on the vascular permeability and volume in the parietal cortex of normal nude mice using two-photon microscopy and immunohistochemistry.

METHODS AND MATERIALS

The upper part of the left hemisphere of 55 mice was irradiated anteroposteriorly using 18 vertically oriented beams (width 25 microm, interdistance 211 microm; peak entrance doses: 312 or 1000 Gy). At different times after microbeam exposure, the microvasculature in the cortex was analyzed using intravital two-photon microscopy after intravascular injection of fluorescein isothiocyanate (FITC)-dextrans and sulforhodamine B (SRB). Changes of the vascular volume were observed at the FITC wavelength over a maximum depth of 650 mum from the dura. The vascular permeability was detected as extravasations of SRB.

RESULTS

For all times (12 h to 1 month) after microbeam irradiation and for both doses, the FITC-dextran remained in the vessels. No significant change in vascular volume was observed between 12 h and 3 months after irradiation. Diffusion of SRB was observed in microbeam irradiated regions from 12 h until 12 days only after a 1000 Gy exposure.

CONCLUSION

No radiation damage to the microvasculature was detected in normal brain tissue after a 312 Gy microbeam irradiation. This dose would be more appropriate than 1000 Gy for the treatment of brain tumors using crossfired microbeams.

Oral health status and needs for dental treatment in geriatric patients in a Danish district hospital

Oral health status and dental treatment needs were investigated in 50 randomly selected patients in the geriatric department of a Danish district hospital. All the participants were examined clinically and radiologically. Oral health status was generally poor. Ten participants required no dental treatment. The remaining 40 participants needed some kind of treatment, mainly prosthetic and surgical. The 40 participants requiring treatment were all asked whether or not they wanted the proposed treatment. Only 18 were interested. The participants were divided into three groups according to their medical status. 28 participants had a poor medical status. It was estimated that these patients once having left the hospital would never be able to visit a dentist on their own initiative, and therefore should be treated institutionally.

Prognosis of survival in a geriatric population

With the aim of demonstrating prognostics as regards death in a geriatric population, the mortality among 1 486 patients (516 men and 970 women) in De Gamles By, Copenhagen, was observed over a 2-year period. The mortality curves for the groups examined were found to be rectilinear in logarithmic form and could therefore be described with sufficient certainty by one value, viz. the probability of death in any one year. The probability of death was just over 20% and was the same for both sexes. Of the parameters examined, particularly high mortality was found where there was urinary incontinence, severe mental abnormality, a great need for nursing, and poor physical mobility (especially inability to walk). On the other hand, there was no particular relationship with age. Where the degree of the handicapping factors was severe, there was generally greater mortality among the men than among the women, but this was not so in the less severe cases. The length of stay in the institution had no effect on the mortality. The results of the present study are in good agreement with previous findings reported from New York (7).

Mortality and functional prognosis in a geriatric population

The prospects of survival and changes in function (need for care) are evaluated after a two-year period for the 1486 persons resident in the geriatric institution "De Gamles By", Copenhagen, on January 15, 1967. It is shown that the logarithm of the survival percentages is approximately a linear function of the time. The prospect of survival is slightly better for the females than for the males because of a significantly higher mortality among the dependent men than among the dependent women. There is no difference as regards sex in the mortality rate for the independent patients (25%). The prospect of survival is poorest in the heavily dependent patients, regardless of sex. Only 5% of the patients were discharged to their homes or transferred to a hospital or some other institution. There was an improvement in the care status, regardless of sex, in 4%, the condition was unchanged in 61%, and there was deterioration in 35% of the 870 patients who survived the two-year period. On the basis of the prospects of surviving whilst waiting for admittance, the saving in institutional places is discussed. The increased need for more accomodation in geriatric institutions is emphasized in order to reduce the unfortunate consequences of the time spent in waiting for admission.

Changes in age and need for care among patients in a geriatric institution during a two-year period

Two cross-sectional studies, carried out at an interval of exactly 2 years at a geriatric institution accomodating about 1400 residents, show an increase in the age of the patients and in the need for care after the 2 years. An analysis of the conditions shows that the changes are due to the surviving patients becoming older and in need of more care, without adequate compensation for this trend having been taken into account when admitting new patients. The admittance and staff aspects connected with these changes are discussed.