Polymer brushes based on PLLA-b-PEO colloids for the preparation of protein resistant PLA surfaces.

In this study we investigate the formation of protein-resistant polymer surfaces, such as aliphatic polyesters, through the deposition of self-assemblies of amphiphilic poly(l-lactide)-b-poly(ethylene oxide), PLLA-b-PEO, copolymers as stable nanoparticles with a kinetically frozen PLLA core on model PLLA surfaces. The length of the PEO chains in the corona was tuned to achieve polymer brushes capable of preventing protein adsorption on PLA-based biomaterials. The spectroscopic ellipsometry, IR and XPS analysis, contact angle goniometry, and AFM proved that the PEO chains adopted a brush structure and were preferably exposed on the surface. The low-fouling properties of the physisorbed PLLA-b-PEO layers approached the ones of reactive grafting methods, as shown by surface plasmon resonance spectroscopy. The anti-fouling properties of the prepared PEO brushes provided sufficient interface to prevent cell adhesion as proved in vitro. Thus, the developed surface coating with PLLA-b-PEO colloids can provide an anti-fouling background for the creation of nanopatterned biofunctionalized surfaces in biomedical applications.

Nano-colloid printing of functionalized PLA-b-PEO copolymers: tailoring the surface pattern of adhesive motif and its effect on cell attachment.

In this study, we investigate the preparation of surface pattern of functional groups on poly(lactide) (PLA) surfaces through the controlled deposition of core-shell self-assemblies based on functionalized PLA-b-PEO amphiphilic block copolymers from selective solvents. Through grafting RGDS peptide onto the functionalized copolymer surface, the presented approach enables to prepare PLA surfaces with random and clustered spatial distribution of adhesive motifs. The proposed topography of the adhesion motif was proved by atomic force microscopy techniques using biotin-tagged RGDS peptide grafted on the surface and streptavidin-modified gold nanospheres which bind the tagged RGDS peptides as a contrast agent. The cell culture study under static and dynamic conditions with MG63 osteosarcoma cell line showed that the clustered distribution of RGDS peptides provided more efficient initial cell attachment and spreading, and resistance to cell detachment under dynamic culture compared to randomly distributed RGDS motif when with the same average RGDS peptide concentration.

Is obesity a preventive factor for lung cancer?

Lung cancer is a disease with multifactorial etiology, smoking playing the most important role among its risk factors. Some studies, however, indicate an inverse association between increased body-mass index (BMI) and the risk of lung cancer. In this paper, the association between BMI and lung cancer risk is analysed in two independent studies. In the first study, 751 lung cancer patients were compared to 30 058 controls. In the second study, 91 lung cancer patients were matched to 91 healthy controls. An inversed association was found between increased BMI and lung cancer risk. The inverse association remained significant after adjustment for age, sex, and smoking.

[Tetanus immunity in the elderly in the Czech Republic]. / Imunita proti tetanu u starsích osob v Ceské republice.

The study objective was to test immunity against tetanus in the elderly in the Czech Republic. Within serological surveys and in old people's homes, 776 persons aged 60 years or more were tested for antibodies against tetanus by an ELISA method. As many as 91 % of these persons had medium to high titers of antibodies against tetanus. Low but presumably still protective titers of antibodies against tetanus were detected in 9 % of the population tested. We documented good immunity against tetanus among the elderly in the Czech Republic as a result of a rich immunization history in this country as compared with some other countries in the world. The sporadic incidence of tetanus cases in the Czech Republic over the last 15 years indirectly indicates the efficacy of the immunization strategy used.

[Risk factors for tumors, cardiovascular and metabolic diseases in the population of the Sumperk District]. / Rizikové faktory nádorových, kardiovaskulárních a metabolických nemocí u populace okresu Sumperk.

BACKGROUND: Cardiovascular diseases and cancers are responsible for almost 80% of the total mortality in the Czech Republic. For their prevention, identification of risk factors becomes indispensable. Presented article analyses frequency of risk factors in the population of Sumperk district on the bases of the first and second preventive oncological check-ups. METHODS AND RESULTS: Diagnoses have been unified according to the International Classification of Diseases. For data analysis SPSS statistical software has been used. Frequency of obesity, hypertension, hyperglycemia, hypercholesterolemia, hyperuricemia and smoking has been assessed in subjects during their first and second preventive check-ups. In the course of the first check-up 49,426 subjects have been examined, out of them 22,857 males (46.2%) and 26,569 females (53.8%). 40,386 subjects participated in the second check-up (18,378 males and 22,008 females). The assessment of the frequency of the individual risk factors has been done on the bases of the examination results. CONCLUSIONS: Total incidence of obesity was lower in males comparing to the data from the population of 6 districts of the Czech republic (MONICA). Due to the treatment of subjects, there was a mild decrease of prevalence of the systolic hypertension in the second check-up in comparison with the first one. In comparison with MONICA project, the incidence of hypertension was more than twice higher. No difference in frequency of hyperglycemia in males and females was found. In both genders, high prevalence of hypercholesterolemia (about 70%) was found. Between two check-ups, decrease of hypercholesterolemia prevalence was observed. It corresponds with the existing trend in the Czech population. Decrease of smoking prevalence has been observed in the second check-up mainly in males and less in females. In comparison with MONICA project, there was a higher smoking prevalence in males and a lower one in females.

Pharmacokinetics and distribution of 125I-PLA-b-PEO block copolymers in rats.

The PLA-b-PEO block copolymers were studied as potential carriers for anti-inflammatory and anticancer drugs. The copolymers were labeled with 125I, and their micelles in physiological saline were prepared by dialysis. Copolymer 1, with Mw = 12,360 (PLA/PEO = 7000/5000), formed particles of about 300 nm in diameter (Rh was 150 nm), whereas copolymer 2, with Mw = 20,470 (6000/14,000), made up micelles of about 72 nm in diameter (Rh was 35.8 nm). Their pharmacokinetic and biodistribution profiles were compared in normal rats and rats with carrageenan-induced inflammation after intravenous application of about 5 mg/kg of each copolymer. Copolymer 2, forming smaller particles, showed longer distribution and elimination half-lives. Both copolymers under study exhibited significantly higher uptake by inflammatory tissue compared with noninflammatory one. The study indicates that PLA-b-PEO copolymers, having different molecular weight of the chains, have similar biological behavior in most organs and tissues. Differences in the uptake by some organs (mainly kidney and bowels) and in activity level in blood at later time intervals were found. Significantly different clearance values are due to different ratios of hydrophobic and hydrophilic chains of the copolymers.

Functionalized surfaces of polylactide modified by Langmuir-Blodgett films of amphiphilic block copolymers.

To modify the surface of poly(L-lactide) (PLA) supports, we have investigated the feasibility to deposit on the PLA surface Langmuir-Blodgett films of amphiphilic block copolymers based on poly(L-lactide). AB and ABA block copolymers were prepared with PLA as the A block and either poly(ethylene oxide), alpha-methoxy-omega-hydroxy poly(ethylene oxide), alpha-carboxy-omega-hydroxy poly(ethylene oxide) or poly(L-aspartic acid) as the B blocks. Films with phase-separated hydrophilic and hydrophobic blocks in a bilayer "brush" structure were prepared by compression of the copolymer Langmuir films on the water/air interface. The interfacial behavior of the monolayers and the effect of the copolymer composition on the phase separation was followed by measurements of the surface-pressure/area isotherms using a Langmuir trough and by contact angle measurement of deposited Langmuir-Blodgett (LB) films. The phase separation of the hydrophilic and PLA blocks is more effective in diblock AB copolymers compared with triblock ABA copolymers. The presence of ionic groups in the hydrophilic chains facilitates penetration of hydrophilic segments into the water subphase. Dynamic contact angle measurements were used to study the stability of the LB-films transferred on the PLA support and the changes in the surface properties upon incubation of surfaces in water.

[Clinical features and therapy of giant cell temporal arteritis]. / Klinický obraz a terapie obrovskobunecné temporální arteriitidy.

Giant-cell temporal arteritis is an urgent condition in ophthalmology as successful treatment depends on early diagnosis and effective therapy before the development of ophthalmological symptoms. The authors investigated on a long-term basis five patients. In the first one complete regression of general and ocular symptoms occurred and vision was preserved. The second patient was admitted already with loss of vision of one eye and despite intensive treatment it did not prove possible to save vision of the second eye. The third patient developed, after clinical recovery, a relapse which was again brought under control. In another patient of relatively younger age it proved possible to arrest the progress of the disease without loss of vision. In the last patient visual acuity improved after treatment.

The incidence of acute myocardial infarction in the district Olomouc in 1994--descriptive study.

Cardiovascular mortality and morbidity in the Czech Republic are among the highest in the world. The morbidity data, however, are not routinely registered and thus a basis for preventive program evaluation is not available. Aim of the study is to establish the incidence of acute myocardial infarction in the Olomouc district in 1994 and to compare it with the incidence of this disease in the Czech Republic. Cases of acute myocardial infarction (diagnosis 121 according to the 10th revision of ICD established by a physician) were included. Sources of data concerning the diagnosis included the registries of internal clinics, departments of internal medicine, department of forensic medicine of the Faculty of Medicine in Olomouc, and general practitioners practising in the Olomouc district. Data concerning myocardial infarction mortality were obtained from the Olomouc Regional Statistical Office. The 6th version of EPI-Info Programme was used to process the data. In 1994, 523 cases of acute myocardial infarction were diagnosed in the Olomouc district, 313 in men and 210 in women. The respective incidence per 100,000 inhabitants was 227: 286 in men and 178 in women. Acute myocardial infarction mortality per 100,000 in Olomouc district was 98.05, it is 109.57 in men and 87.26 in women. For comparison, acute myocardial infarction mortality per 100,000 in the Czech Republic at the same period was 171.4 and 117.2 for men and women, respectively. Highest incidence was observed in March and October/November, lowest occurrence was observed in July and August. The incidence decreased with increasing size of the place of residence. As to the latter, further analysis is required to formulate conclusions concerning the morbidity trends.

[ProVisc--a new viscoelastic material for surgery of the anterior segment. A multicenter clinical study]. / ProVisc--nový viskoelastický materiál pro chirurgii predního segmentu. Multicentrální klinická studie.

Within the framework of a multicentric clinical study which was implemented at nine selected departments a new viscoelastic material ProVisc of Alcon company was tested during extracapsular extraction of cataract with implantation of posterior chamber intraocular lenses. A total of 100 eyes of 100 patients were operated and all pre- and postoperative data were recorded in uniform protocols. The selection of suitable patients and the type of surgical procedure was within the responsibility of the surgeon. The type and frequency of surgical and postoperative complications was similar as when other viscoelastic material ProVisc can be recommended as safe and effective in modern surgery of cataract.

[Collagen architecture of sclerocorneal trabeculae in relation to age]. / Kolagenní architektura sklerokorneálního trabekula v závislosti na veku.

The authors investigated the collagen architecture of the sclerocorneal trabeculum in relation to age in eight eyes within the range from a premature infant to a 90-year-old man. All specimens were investigated using a scanning electron microscope of Jeol Co. The appearance of fibrils does not change substantially in relation to age, however, their pattern and distribution change. In a 10-year-old boy Schlemm's canal is wide, oval with thin trabecular plates and wide open spaces surrounding them. In the 90-year-old man the canal is open but the plates on its luminous side are thickened, wrinkled and compressed. On the albuminous side there is a compact wall of compressed collagen layers.

Distribution of microspheres in the brain of hypertensive rats.

The blood perfusion of different parts of the brain tissue was examined by means of microspheres 15 and 50 micron in diameter, in normotensive control rats and in animals with experimental renovascular hypertension. The microspheres were labelled with fluorescein isothiocyanate and their numbers in the tissue were determined in consecutive histological sections by UV microscopy. In the control rats, the incidence of wedged microspheres per 1 mm3 tissue was high in the cerebellum, cerebral cortex, subcortical tissue and pons Varolii, but low in the thalamic and hypothalamic regions, indicating that these parts were relatively poorly perfused with blood. The significantly greater accumulation of microspheres in the cortex and subcortical tissue of hypertensive rats seems to have been due to hypertensive narrowing of the arterioles. Conversely, the diminished incidence of microspheres in the thalamus and hypothalamus may have been due partly to microsphere trapping in the narrowed upstream blood vessels and partly to thinning of the capillary network. Total microsphere recovery in the brains of the control and the hypertensive rats was almost identical, implying that only the distribution of brain blood perfusion is altered in experimental hypertension.

Early stages of experimental atheromatosis.

In female Wistar rats, fed an atherogenic diet, the early changes of serum lipids and the deviation of the vasomotor response to adrenaline and acetylcholine were compared with morphological manifestations. It has been found that the first sign may be detected as the shift in serum lipoproteins and lipids just in a few days. Merging and decrease of alpha-lipoproteins and an increase of the beta-lipoprotein fraction proved as the most sensitive indicator. In the course of several weeks, an alteration of hemodynamic response to adrenaline and acetylcholine occured. The animals revealed a diminished depressoric response to acetylcholie, whereas their blood pressure response to adrenaline in the pressoric phase was decreased but the depressoric phase was markedly expressed. The morphological impairment of the vascular system followed with a delay of several months, although a lipoid infiltration of the liver appeared after 6 weeks of the atherogenic dietary regimen.