Journal of X-Ray Science and Technology

Macromolecular photosensitizer conjugates are under investigation as improved delivery vehicles for dyes used in photodynamic therapy. We have previously described the use of conjugates between photosensitizers such as chlorin $_{e6}$ (c $_{e6}$ ) and poly-L-lysine (pL) chains which are versatile molecular species because the size of the chain can be varied, and the overall charge can be altered from cationic through neutral to anionic. We now report on a series of pL-c $_{e6}$ conjugates in their cationic (native), neutral (acetylated) and anionic (succinylated) forms, where the number of c $_{e6}$ molecules attached to each chain was varied (pL: c $_{e6}$ ratios, 1:4, 1:8, 1:12, and 1:16). The fluorescence emissions were measured in both saline and a disaggregating solvent. We studied two cell lines (an epithelial ovarian cancer, OVCAR-5 and a mouse macrophage, J774) and measured cellular uptake, subcellular localization (by confocal fluorescence microscopy) and phototoxicity. The cellular uptake of the conjugates with four substitution ratios all delivered at 2 μM c $_{e6}$ equivalent concentration showed a maximum at 12 c $_{e6}$ per chain for both cationic and anionic conjugates, but the uptake of the neutral conjugate was proportional to the substitution ratio. The macrophages took up several times more c $_{e6}$ than the ovarian cancer cells. Confocal fluorescence micrographs showed more cellular fluorescence with the lower substitution ratios, and more lysosomal localization with the cationic conjugates. The phototoxicity was much higher for the neutral conjugates. For the cationic and neutral conjugates the 12 c $_{e6}$ per chain was the most effective at killing cells, while for the anionic conjugate it was the 16 c $_{e6}$ per chain. The anionic conjugate was better at killing OVCAR-5 cells, while the cationic was better for J774 cells, and the neutral was approximately the same. These data will help to optimize the parameters to be used in preparing polymeric-photosensitizer conjugates for photodynamic therapy.

It is established that a natural system balances functional requirements with the anatomical optimizations it has achieved. Though such process of functional adaptation is recognized in bone tissue, any mode of functional adaptation in dental tissue is yet to be understood. In this study a three-dimensional digital photoelasticity is conducted to evaluate the nature of stress distribution in the sagittal aspect and the cross-sections of the dentine structure. Later, a fluoroscopic X-ray microscopic analysis and a microindentation experiments, are performed on different sections obtained from the sagittal and cross-sections of the dentine. These experiments aided in correlating the multi-plane pattern of mineralization and the spatial gradients in elastic modulus in the original dentine structure with the three-dimensional stress distribution in photoelastic models. This study highlights dentine structure as a biologically graded structure to functional loads.

The highly scattering nature of human tissue limits light penetration depth in the near infrared range, which prevents the deeper microstructures from imaging. In order to enhance the imaging depth for the current high resolution optical imaging techniques, the light scattering in tissue must be reduced. This paper demonstrates that the light scattering of tissue can be effectively reduced by the topical applications of the biocompatible chemical agents. In this study the propylene glycol and glucose solutions were chosen for the demonstrations through topical applications and intra-dermis injection, respectively. The experiments were performed in vitro and in vivo by the use of the optical coherence tomography system. The results clearly show that the OCT imaging depth and contrast are dramatically improved after the topical applications of propylene glycol solution. Such improvement was discussed on the basis of refractive index matching environment created by the chemical agents, which effectively reduces the light scattering of tissue. Rayleigh-Gans approximation of light scattering was also used to show theoretically how the increase of refractive index of background medium would have effect on the reduced scattering coefficient of tissue. The theoretical and experimental results were qualitatively consistent.

The aim of this study was to compare interstitial laser thermotherapy with excision of a liver tumour. A dimethylhydrazine-induced adenocarcinoma was implanted into the left lateral lobe of the rat liver, and treatment was performed 8 days later. Rats were treated with resection of the tumour-bearing lobe or underwent interstitial laser thermotherapy, which was performed at a steady-state temperature of 46°C for 30 min, 3 mm from the tumour margin. The incidence and extent of intraperitoneal spread was smaller after laser thermotherapy than after resection, with no difference in local control. Using inoculation of tumour cell suspensions into the lateral and the median lobes of the liver simultaneously and treating the lateral lobe tumour only, we found that laser thermotherapy reduced take and growth of the untreated tumour in the median lobe indicating that laser thermotherapy may induce immunologic effects. It is concluded that interstitial laser thermotherapy reduces spread of liver tumour as compared to resection. It is suggested that this can be at least partly explained by a laser-induced immunologic effect.

Diabetes is a disease which severely threatens the health of human beings. Unfortunately, current monitoring techniques with finger sticks discourage the regular use. Noninvasive spectroscopic measurement of blood glucose is a simple and painless technique, and reduces the long-term health care costs of diabetic patients due to no reagents. It is suitable for home use. Moreover, the establishment of the methodology not only applies to blood glucose noninvasive measurement, but also can be extended to noninvasive measurement of other analytes in body fluid, which will be of important significance for the development of the technique of clinical analysis.

In this paper, some fundamental researches, which have been achieved in our laboratory in the field of non-invasive blood glucose measurement, were introduced.

1. Fundamental research was done for the glucose concentrations from simple to complex samples with near and middle infrared spectroscopy:

(1) the relationship between the instrument precision and prediction accuracy of the glucose measurement;

(2) the change of the result of the quantitative measurement with the change of the complexity of samples;

(3) the attempt of increasing the prediction accuracy of the glucose measurement by improving the methods of modeling. The research results showed that it is feasible for non-invasive blood glucose measurement with near and middle infrared spectroscopy in theory, and the experimental results, from simple to complex samples, proved that it is effective for the methodology consisting of hardware and software.

2. According to the characteristics of human body measurement, the effects of measuring conditions on measurement results, such as: (1) the effect of measurement position; (2) the effect of measurement pressure; (3) the effect of measurement site; (4) the effect of measured individual, were investigated. With the fundamental researches, the special problems of human body measurement were solved. In addition, the practical and effective method of noninvasive human blood glucose measurement was proposed.

The materials on the basis of alkali-halide crystals for recording the X-ray images are developed. Their spatial resolution is 1 μm, dynamic range of recording is more than 10000. The media allow readout without erasing the image and extended storage of the image. The examples of their use in X-ray microscopy of biological objects are shown.

The mechanisms of disturbance of lymph microcirculation during development postmastectomy lymphedema (PML) are little known. The study of these mechanisms on human subjects has many difficulties: time of clinical onset of PML is indefinite and unpredictable and the methods for imaging of microlymphatics are limited. The advantages of the optical methods, especially, light microscopy are the high quality of lymphocytes dynamic imaging, possibility of the determination of absolute lymph flow velocity in a wide range, capability for simultaneous registration of blood microvessel function around lymphatics. The experimental lymphedema is created on rat mesentery by ligation of the collecting vein. It was found that after such ligation edema was clearly developed, and microcirculation was significantly disturbed including reduction of lymph flow velocity, constriction of lymphatics, inhibition of phasic activity on the background of pathological increasing of blood vessels permeability and stasis of blood flow.

The use of several different drugs and different treatment modalities often leads to synergistic effects in treating diseases, such as cocktail therapy in AIDS treatment and combination therapy in chemotherapy treatment of cancer patients. With the wide application of lasers in the treatment of cancers, can the synergistic effect manifest itself in the combination application of lasers and other treatment components, particularly those related to immunological stimulation? Selective photothermal interactions using a laser and a light-absorbing dye have been used in combination with immunological interactions using an in situ immunoadjuvant in treating metastatic tumors. Three components were used in this method: a near-infrared laser, a light-absorbing dye and an immunoadjuvant. This new method -- Laser Immunotherapy -- has achieved the synergistic effect. This novel approach has been applied in treating metastatic mammary tumors in rats. In our animal studies, when the components were applied individually, or in two-component combinations, the long-term effect of cancer treatment was almost negligible. However, when the three components were used at the same time, the treatment effect improved significantly. In this study, we show the synergistic effect using an 805~nm laser, indocyanine green (ICG) as the light-absorbing dye, and glycated chitosan, a novel compound, as the immunostimulant. Furthermore, optimization of the laser-dye photothermal interaction using different laser and dye parameters in an in vitro study using tissue-simulating gel phantoms was performed. Our results showed that the optimal photothermal effect could be achieved using 1.8 watts and 0.5~cm beam radius, and an ICG concentration between 0.08 to 0.14% effect of immunoadjuvant, three additional adjuvants, complete Freund's adjuvant, incomplete Freund's adjuvant, and C-parvum were also used in laser immunotherapy. Glycated chitosan appeared to be the most effective. The complete Freund's adjuvant at a dose of 200 μl and 50% concentration resulted in a cure rate comparable to that using glycated chitosan. Incomplete Freund's adjuvant and C-parvum showed relative weak effects in treating the metastatic tumors.

Indocyanine green (ICG), with spectral absorption at 800--810 nm, is a chromophore that strongly absorbs and converts near-infrared laser energy into thermal energy. By directly injecting ICG into a tumor, selective tumor hyperthermia during laser irradiation occurs. In this study, 4 dogs with spontaneous tumors were injected in situ with a 0.25% energy. Thermal data were collected from multiple thermocouples placed within the tumor and tumor response was recorded. Tissue heating to ≥ 42°C was observed in all tumors. One dog had a complete remission, one dog had stable disease for 12 weeks, and the other 2 dogs developed progressive disease shortly after treatment. Results from this study demonstrate that chromophore-enhanced laser-induced hyperthermia can effectively and selectively heat canine tumors. However, tumor size and pigmentation of overlying skin are potentially limiting factors to the success of this novel c ancer treatment.