Impact of COVID-19 on the performance of a radiation oncology department at a major comprehensive cancer centre in Poland during the first ten weeks of the epidemic.

The outbreak of SARS-CoV-2 coronavirus rapidly altered radiotherapy service delivery around the world. AIM: The main objective of this study was to assess the impact of precautionary measures implemented in response to the COVID-19 pandemic on the performance of a radiation oncology departments and on mitigation the risk of COVID-19 contagion between and among patients and staff. METHODS: The study period was from March 15 until May 22, 2020. We evaluated total number of patients irradiated and those who initiated treatments, taking into account tumours localisations. We assessed the relationship of potential risk of contagion with patients' domiciles locations in regions with high number of COVID19 case. RESULTS AND CONCLUSIONS: The number of patients treated with radiotherapy during the study period decreased due to precautionary measures. After five weeks, the number of radiotherapy treatments began to increase. Just over half of the radiotherapy patients (53.5%) treated at the GPCC reside in the city of Poznan or in one of the ten surrounding counties where COVID19 incidence was low and reached at the end of the study period cumulative number of cases n = 204. The precautionary measures were effective qRT-PCR tests were performed in 1545 individuals (patients and hospital staff) revealing four staff members and none patient with a positive PCR result. Immunoglobulin testing was performed in 1132 individuals (patients and hospital staff). A total of 63 individuals were positive for antibodies.

Characterization of mesoporous aluminosilicate materials by means of inverse liquid chromatography.

Estimation of the properties of mesoporous aluminosilicates in various environments is important when assessing their sorption capacity. Using inverse liquid chromatography (ILC), Hansen solubility parameters (HSP) and linear free energy relationship (LFER) parameters were calculated to determine the properties of aluminosilicates in a protic and an aprotic system, using water and acetonitrile as the mobile phase, respectively. The calculated Hansen parameters, reflecting the ability of the material under investigation to different types of intermolecular interactions, slightly differ depending on the mobile phase used. It was found that in the presence of water the surface of aluminosilicates shows a weaker ability to interact, as evidenced by negative or near-zero e, s, a, b, v coefficients. Additionally, it was found that the Si/Al ratio in aluminosilicates structure has little effect on the determined parameters.

The solubility parameter for biomedical polymers-Application of inverse gas chromatography.

The solubility parameter seems to be a useful tool for thermodynamic characterisation of different materials. The solubility parameter concept can be used to predict sufficient miscibility or solubility between a solvent and a polymer, as well as components of co-polymer matrix in composite biomaterials. The values of solubility parameter were determined for polycaprolactone (PCL), polylactic acid (PLA) and polyethylene glycol (PEG) by using different procedures and experimental data, collected by means of inverse gas chromatography.

A dosimetric comparison of IMRT versus helical tomotherapy for brain tumors.

BACKGROUND AND PURPOSE: Helical tomotherapy (HT) can deliver highly conformal, uniform doses to the target volume. However, HT can only be delivered in a coplanar mode. The purpose of this study was to perform a dosimetric comparison of HT versus coplanar (cIMRT) and non-coplanar (n-cIMRT) beam arrangements on a conventional linear accelerator in a diverse group of brain tumors. MATERIALS AND METHODS: A total of 45 treatment plans were calculated retrospectively for 15 cases. For each case, 3 different delivery techniques (n-cIMRT, cIMRT and HT) were used. The treatment plans were compared using the parameters of the target coverage (conformity index; CI) and homogeneity (HI) for the planning target volume (PTV) and the maximum and mean doses for organs at risk (OARs). RESULTS: Median HI and CI were the best for HT plans and the worst for cIMRT. The largest reduction of maximum dose for lenses and mean dose for both eyes was achieved for n-cIMRT plans. Mean dose for chiasm and the ipsilateral optic nerve were the lowest for HT. The contralateral optic nerve was most spared with n-cIMRT. For D1% in the brain stem, there was no significant difference between HT and the IMRT plans. CONCLUSIONS: Both HT and n-cIMRT are capable of producing conformal and homogeneous treatment plans with a good sparing of OARs. However, due to the non-coplanar capabilities of IMRT, n-cIMRT led to a superior dose reduction to the lenses.

The increase of apatite layer formation by the poly(3-hydroxybutyrate) surface modification of hydroxyapatite and ß-tricalcium phosphate.

The aim of this study was the surface modification of hydroxyapatite and ß-tricalcium phosphate by poly(3-hydroxybutyrate) grafting and characterization of modificates. The bioactivity examination was carried out by the determination to grow an apatite layer on modified materials during incubation in simulated body fluid at 37°C. The additional issue taken up in this paper was to investigate the influence of fluid replacement. The process of the surface modification of biomaterials was evaluated by means of infrared and Raman spectroscopy. Formation of the apatite layer was assessed by means of scanning electron microscopy and confirmed by energy dispersive, Raman and Fourier transformed infrared spectroscopy. During exposure in simulated body fluid, the variation of the zeta potential, pH measurement and relative weight was monitored. Examination of scanning electron microscopy micrographs suggests that modification of hydroxyapatite and ß-tricalcium phosphate by poly(3-hydroxybutyrate) significantly increases apatite layer formation. Raman spectroscopy evaluation revealed that the formation of the apatite layer was more significant in the case of hydroxyapatite modificate, when compared to the ß-tricalcium phosphate modificate. Both modificates were characterized by stable pH, close to the natural pH of human body fluids. Furthermore, we have shown that a weekly changed, simulated body fluid solution increases apatite layer formation.

Arterial stiffness in relation to subclinical atherosclerosis.

BACKGROUND: Increased arterial stiffness or arteriosclerosis, represents a physiological part of ageing. Atherosclerosis is a process that does not affect the arterial bed uniformly but has a variable local distribution and is frequently superimposed on stiffened vessels. We therefore addressed the question of whether any correlation exists between the general characteristics of arterial stiffness or wave reflection and subclinical atherosclerosis as assessed by carotid intima-media thickness (IMT) in a sample of healthy subjects. METHODS: A total of 116 healthy subjects (mean age 55 years, 43 female) were evaluated. Arterial stiffness and wave reflection was assessed with the use of digital volume pulse analysis (DVP) and pulse wave analysis (PWA). Subclinical atherosclerosis was assessed by measurement of IMT. RESULTS: Stiffness Index (SI(DVP)), the measure of general arterial stiffness correlated significantly with IMT (r = 0.37, P < 0.01). IMT correlated significantly with age (r = 0.5, P < 0.0001), waist to hip ratio (WHR) (r = 0.39, P < 0.0001) and mean blood pressure (BPmean) (r = 0.4, P < 0.0001). IMT did not correlate with measures of wave reflection. SI(DVP) correlated significantly with age (r = 0.32, P < 0.005), WHR (r = 0.36, P < 0.0001), BPmean (r = 0.36, P < 0.0001) and measurements of wave reflection. However analysis of a model which included variables that significantly influenced SI(DVP) and IMT, such as age, WHR and mean BP showed that arterial stiffness is not independently associated with subclinical atherosclerosis. CONCLUSIONS: The indices of subclinical atherosclerosis, arterial stiffness and wave reflection, indicate different aspects of vascular status in otherwise healthy subjects.

New procedure for the determination of Hansen solubility parameters by means of inverse gas chromatography.

The Hansen solubility parameter (HSP) seems to be a useful tool for the thermodynamic characterization of different materials. Unfortunately, estimation of the HSP values can cause some problems. In this work different procedures by using inverse gas chromatography have been presented for calculation of pharmaceutical excipients' solubility parameter. The new procedure proposed, based on the Lindvig et al. methodology, where experimental data of Flory-Huggins interaction parameter are used, can be a reasonable alternative for the estimation of HSP values. The advantage of this method is that the values of Flory-Huggins interaction parameter chi for all test solutes are used for further calculation, thus diverse interactions between test solute and material are taken into consideration.

Cell cycle and apoptosis in tumours of oral cavity estimated by image cytometry.

The aim of investigations was to examine whether diploid and aneuploid tumours of oral cavity differ in frequencies of occurrence of individual phases of cell cycle and of apoptosis. Investigations were carried out on 53 tumours using techniques of image cytometry. The studies were performed on properly isolated cells of tumours, which were stained using Feulgen method and analysed by image cytometry. Using a suitable computer programme, the percentages of cells present in individual phases of cell cycle and in apoptosis were estimated. No respective differences could be disclosed between diploid and aneuploid tumours. In addition, the ratios of the fraction of cells in S phase of the cell cycle and those in apoptosis were calculated and were found to carry certain prognostic significance in patients with squamous cell carcinomas of oral cavity.

DNA ploidy in malignant melanoma, skin cancer and pigmented nevi.

The determination of DNA content in human cancers is the subject of increasing interest, particularly in view of its potential clinical applications. There are relatively few studies which describe DNA content of skin neoplasms and pigmented nevi. These studies have shown conflicting results. In the present investigation the authors measured DNA ploidy using flow and video-imaging cytometry in 51 malignant melanomas, 20 skin cancers and 48 pigmented nevi. For DNA measurement paraffin embedded tissues and fresh cell smears were used. Clinical and histological data of malignant melanomas were recorded and correlated with DNA ploidy. DNA histograms were examined for DNA aneuploidy by DNA Index. DNA ploidy in primary lesions of melanomas and their metastases were compared. The aneuploidy rate, found in our observation, was significantly higher in whole malignant melanoma group, in clinical Stage II and III, in tumors with thickness greater then 1.5 mm, tumors with Clark level III, IV and V. Another clinical and histological factors did not show significant correlation with ploidy. Aneuploidy was found in 8 of 20 (45.0%) skin cancers. In the whole population of pigmented nevi aneuploid DNA content was identified in 10 nevi (20.1%). The results of this study suggest that aneuploidy seems to be connected with advanced stage of malignant melanoma but it does not replace other prognostic factors. Both cytometric methods can be used for routine DNA ploidy analysis. Ploidy studies are not useful for predicting metastatic potential of primary melanoma. Results obtained from fresh cell smears and paraffin embedded tissues were identical.