Biomedical subjects

J Lukás

Publications and source records attributed to J Lukás.

At least 19 recordsLinked to original sources

PubMed2003

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.

Journal Article↗

PubMed2002

[Acute pharyngotonsillitis].

The article reviews rent findings on the acute pharyngotonsilitis. In the aetiology of the disease viral infections prevail. In the bacterial aetiology of the acute pharyngotonsilitis mainly group A streptococci predominate. Individual types of pharyngotonsilitis are specified, and their typical clinical symptoms, diagnostics and therapy are given.

Acute Disease↗

PubMed2001

[Injuries of the upper and middle thirds of the face. Analysis of the cause of injury] ].

BACKGROUND: From the point of traumatologist, the size, locality and direction of the injuring force give the extent of the injury of facial skeleton. The aim of the paper is to present an overview on aetiology of injuries of the upper and medial third of face in relation with the incidence, gender and age of patients. METHODS AND RESULTS: 282 adult patients (208 males and 74 females, average age 40 years) and 25 children (18 boys and 7 girls, average age 9 years) were treated since 1.1.1998 till 31.8.1999. 25 of them (9%, 19 males and 6 females) had fracture of the middle third of the face. In 5 patients (20%), fractures were accompanied by commotion of the brain. Conservative treatment was used in 16 patients (64%) and surgical approach in 9 of them (36%). Isolated fractures of nasal bones were diagnosed in 230 adult patients (82%, 168 males, 62 females, 25 children). In 19 adult patients (8%) the fracture was open, in 25 of them the reposition of dislocated bones was done in general anaesthesia. 27 patients (10%, 21 males, 6 females) had polytrauma, accompanied by the facial bones fractures of the upper and middle third. Facial fractures of the upper and middle third were caused by violence of other person (criminal injury) in 15 patients (60%), downfall in 66 patients (29%), sport injury in 38 patients (17%), traffic injury in 16 patients (7%). The most common cause of isolated fracture of nasal bones in children was downfall in 12 patients (48%), violence of other person or schoolmate in 7 patients (28%) sport injury in 5 patients (20%), traffic injury in 1 patient (4%). In 27 persons with polytrauma and facial fractures of the upper and middle third, the injury was caused by traffic accident in 13 patients (48%), downfall in 8 patients (30%), sport injury in 2 patients (7.4%), criminal injury in 2 patients (7.4%), work injury in 1 patients (7.4%). CONCLUSIONS: Polytrauma belongs to the most serious injuries both due to their extent and their significance because in most of them the life of patients is directly threatened. Criminal injuries represent very common cause of the facial fractures of the upper and middle third with maximum prevalence in males of the third decade. Part of those injuries belong to polytrauma.

Adolescent↗

PubMed2001

Biological properties of copolymer of 2-hydroxyethyl methacrylate with sulfopropyl methacrylate.

Interaction of organism with non-toxic implanted polymers depends on the physicochemical properties of the implant surface, which influence the adsorption of bioactive proteins and subsequently adhesion and growth of cells. The synthetic hydrogels are known as poorly adhesive surfaces. In this study we demonstrated the adsorption of albumin, fibrinogen, fibronectin, basic fibroblast growth factor, heparin-binding epidermal growth factor-like growth factor and epidermal growth factor to poly(2-hydroxyethyl methacrylate) (pHEMA) and copolymer of 2-hydroxyethyl methacrylate (HEMA) and potassium salt of 3-sulfopropyl methacrylate (SPMAK). The adhesion and growth of 3T3 cells and human keratinocytes on surface of these polymers was tested without and with pretreatment of polymers with heparin-binding epidermal growth factor-like growth factor. The adhesion of mixture of human granulocytes and monocytes to these surfaces was also tested. The strips of both polymers were subcutaneously and intracerebrally implanted into the rat and the extent of foreign body reaction and brain biocompatibility was evaluated. The results showed the extensive adsorption of basic fibroblast growth factor and heparin-binding epidermal growth factor-like growth factor to copolymer containing SPMAK. However the adhesion (and growth) of cells to this type of copolymers was very low. Preadsorption of human plasma to pHEMA clearly stimulated the leukocyte adhesion in contrary to copolymer containing SPMAK. The extent of foreign-body reaction was significantly higher against the pHEMA compared to tested copolymer p(HEMA-co-SPMAK). In conclusion, the tested copolymer was a poorly adhesive substrate that is only poorly recognized by the non-specific immunity, although the adsorption of basic growth factors to this substrate is highly significant. Both polymers were well tolerated by the brain tissue. The phenotype of surrounding neurons was more close to the control neurons in the brain tissue surrounding the p(HEMA-co-SPMAK) implants.

Journal Article↗

PubMed2001

[Mucoceles of paranasal sinuses].

In a retrospective study authors refer to the treatment results in four patients with mucocele of the paranasal sinuses, who were hospitalized during a 30-months period at the Department of Otorhinolaryngology of the Charles University Hospital, in Prague, Czech Republic. In all patients the frontal sinus was involved, in three cases the involvement was unilateral, in one case bilateral. In the medical history of all patients, an injury, inflammation, or surgery of the paranasal sinus in the past (5-30 years ago) were present. In three patients, proptosis of the eye, swollen upper eyelid, and diplopia were discovered firstly by ocular examination. All patients underwent external approach surgical treatment, in four cases it was the frontoethmoidectomy sec. Jansen-Ritter, in one case the osteoplastic frontal craniotomy was performed. The postoperative follow-up period is 2-30 months.

Adult↗

PubMed2001

[Multiple extrarenal complications in Wegener granulomatosis].

This is a case report of a patient with Wegener's granulomatosis (WG), who initially presented with a corneal perforation. In addition to the eye involvement, the pauciimmune necrotizing glomerulonephritis with crescent formation, E.N.T. and pulmonary involvement were diagnosed. The patient also suffered from the acute myocardial infarction, most likely due to coronal arteritis. In addition to the coronal ischaemia she also had vasculitis of the aortic valve due to the WG. Another rare complication was the massive intestinal bleeding. The patient had also a skin vasculitis and non-specific symptoms such as artralgias and fever. The correct diagnosis was supported by positive cANCA. A clinical and laboratory remission of the disease was achieved by combined immunosuppressive therapy. Subsequently, she developed a subglotic stenosis possibly due to reparative changes.

Adult↗

PubMed1997

Effect of chemical structure of hydrogels on the adhesion and phenotypic characteristics of human monocytes such as expression of galectins and other carbohydrate-binding sites.

The reactivity of diverse immune aspects to the presence of synthetic polymers represents one of the most important aspects of implantable device biocompatibility. In this report, we show the effect of the chemical structure of a synthetic polymer support on monocyte adhesion and selected phenotypic characteristics in vitro as a model for the initial steps of non-self-recognition of an implant. The extent of monocyte adhesion was significantly influenced by the support chemistry. The highest level of monocyte adhesion was observed on a surface copolymer of 2-hydroxyethyl methacrylate with dimethyl aminoethyl methacrylate relative to results of experiments in which poly(2-hydroxyethyl methacrylate) or the copolymer of 2-hydroxyethyl methacrylate with the sodium salt of methacrylic acid was used. Cell adhesion to the polymers tested and to glass was accompanied by enhanced expression of the carbohydrate-binding sites tested for asialoglycoprotein beta-galactosides such as galectins, beta-N-acetylgalactosamine, alpha-mannoside, specific lectin for heparin as well as the lymphokine-macrophage migration inhibitory factor in the monocytes tested. These results suggest the importance of monocyte adhesion to the biomaterial surface for their development into macrophages and further non-self-recognition of the implanted device.

Acetylgalactosamine↗

PubMed1997

Comparative study of human monocyte and platelet adhesion to hydrogels in vitro - effect of polymer structure.

Blood platelet and monocyte adhesion was studied in vitro with respect to the influence of hydrophilic polymer chemical functional groups and their charge. The results showed that the strongest adhesion of human monocytes was to coverslips covered with cationic polymer. Platelet adhesion to all tested polymers proved to be negligible; no differences related to the charge of the polymers used were observed. These results show the obvious difference between the biocompatibility and haemocompatibility in vitro which must be taken into consideration during polymer biological properties testing before clinical trials.

Journal Article↗

PubMed1995

Mapping of endogenous lectins in macrophages colonizing an implanted polymer surface--effect of polymer structure.

The design of synthetic polymers may affect structural features of inflammatory cells, for example the expression of endogenous sugar receptor molecules like lectins in macrophages and foreign body giant multinucleate cells. This characteristic was studied histochemically by use of biotinylated (neo)glycoproteins. The results demonstrate the influence of polymer structure on the phenotypic expression of molecules recognizing carbohydrates in these cells. Very strong activity was observed for carrier-immobilized beta-galactose in cells colonizing hydrophobic polystyrene implants. Sialic acid moieties were not recognized by cells located on the surface of all types of polymeric implant. This study encourages investigation of the influence of polymer design on the differentiation of macrophages.

Animals↗

PubMed1993

Immunohistochemical analysis of the p53 oncoprotein on paraffin sections using a series of novel monoclonal antibodies.

Alterations of the p53 tumour suppressor gene are considered critical events in multistage carcinogenesis of a wide range of human cancers. In an attempt to elucidate the role of various p53 mutations in tumorigenesis and to investigate their relationship to the p53 protein accumulation and subcellular localization, we have raised a new series of 21 mouse monoclonal antibodies (MAbs) to human recombinant p53. The new MAbs (designated the Bp53 series) appear to recognize mainly denaturation-resistant epitopes in immunoblotting and the majority of them are suitable for immunostaining of p53 in cultured cells and frozen sections. Furthermore, at least three MAbs (Bp53-11, Bp53-12, and Bp53-28) proved to be reliable reagents for immunohistochemistry on paraffin-embedded specimens. The immunohistochemical analysis of paraffin sections from 118 human tumours of various histogeneses with Bp53-11 and Bp53-12 showed nuclear accumulation of the p53 protein in variable proportion of tumour cells in 76 cases (64 per cent). The influence of three parameters of tissue processing (type of fixative, period of fixation, and duration of autolysis) on p53 protein detection was also investigated. The results of this study provide the necessary basis for wider application of these novel MAbs as tools in both routine histopathology and functional analyses of the p53 oncoprotein.

Animals↗

PubMed1993

Molecular pathology of the cell cycle in human cancer cells.

Recent evidence from molecular biology studies of the cell cycle machinery suggests that, apart from oncogenes and tumor suppressor genes, the genes encoding the key cell cycle regulatory proteins could serve as additional targets for oncogenic mutations involved in the multistep process of carcinogenesis. In an attempt to identify such potential cancer-associated aberrations of the cell cycle regulators, the expression of cdc2 and cdk2 kinases, as well as cyclins A, B1 and D1, was analyzed by immunoblotting in a panel of more than 40 human cancer cell lines derived from 17 different tumor types. The expression of cdc2, cdk2, cyclin B1 and cyclin A polypeptides was detectable in all lines examined, and moderate variation in protein level does not provide evidence for any obvious abnormalities in the cancer cell lines studied. The application of a series of novel monoclonal antibodies (Mab) to human cdc2 revealed the existence of an intriguing protein, designated p37, immunologically and structurally related to cdc2, which is strongly and selectively expressed in about 50% of the cancer cell lines. In contrast to cyclin A, which has also been implicated in tumorigenesis, we found pronounced variation in abundance of the cyclin D1 protein. Our data suggest that dysregulation of cyclin D1 (a candidate bcl-1, PRAD1 oncogene) can be involved in the pathogenesis of some additional tumor types (e.g., sarcomas and neuroblastomas) besides those reported for amplification and/or mRNA overexpression of this oncogene.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

[A multidisciplinary approach in the treatment of endocrine orbitopathy].

Despite the knowledge of immunological mechanisms of Graves-Basedow's disease the pathogenesis of endocrine orbitopathy remains obscure. Apart from the most frequent association with GB disease it may occur also in patients with primary hypothyroidism, Hashimoto's thyroiditis or in rare instances in euthyroid patients not suffering from thyroid disease. Endocrine orbitopathy is a typical example of a disease with a multidisciplinary approach to its diagnosis and treatment. In the submitted paper the authors demonstrate the collaboration of four clinics of the Faculty Hospital when dealing with this problem. Complete or almost complete removal of the thyroid gland leads within 1-4 years to regression of the protrusion of the bulbus by 1 mm. In combination with decompression of the orbit by a modification of Ogura's and Walsh's method improvement of visual acuity by 50% was achieved and the mean value of the exophthalmus diminished by 3.5 mm.

Exophthalmos↗

PubMed1992

[Aberrations of the p53 antioncogene in malignant tumors].

The results of the present study of the p53 antioncogene in a broad panel of human cell lines (n = 32) and biopsy specimens (n = 435) from both normal and tumour tissues can be summarized as follows: 1. Cells in primary cultures from normal tissues express very low levels of the p53 protein while strong nuclear accumulation of p53 can be seen in all SV 40 transformed human cell lines and the vast majority of tumour--derived cell lines studied. 2. Similarly, in human tissues strong nuclear p53 expression is found in high proportion of malignancies of various histogenesis, in contrast to benign lesions, nonmalignant tissues surrounding malignant tumours and normal tissues in which the p53 protein levels remain below the limits detectable by common immunohistochemical methods. 3. Sequence analysis of p53 mRNA amplified by polymerase chain reaction (PCR) revealed point mutations in the central region of the p53 gene in several cancer cell lines. Furthermore, very good correlation was found between the presence of such mutations and accumulation of the mutated p53 protein. This study confirms and extends our current view of p53 as the gene most frequently altered in human cancer and suggests that simple immunohistochemical methods can be used to screen for aberrations of this antioncogene.

Genes, p53↗

PubMed1992

Distinct forms of human CDC2 identified by novel monoclonal antibodies.

Studies on the functional and structural properties of the cdc2 kinase, a key cell-cycle regulator, have been possible thanks to the availability of cdc2-specific immunoreagents. In an attempt to elucidate the biochemical regulation of the cdc2 kinase in more detail, we have raised a series of novel mouse monoclonal antibodies against human recombinant cdc2 protein. The five Mab reported here can be subclassified into two groups according to their interspecies cross-reactivity and distinct immunoprecipitation patterns. Thus, the target epitopes of Mab POH-1, POH-2 and POH-7 (group 1) appear to be limited to a few mammalian species and the fraction of cdc2 immunoprecipitable by these Mab from cellular extracts is considerably enhanced by denaturation. In contrast, the POH-3 and POH-8 (group 2) Mab recognize a denaturation-sensitive epitope on cdc2 which is present in all tested mammalian species. More importantly, each of the two groups of Mab immunoprecipitate forms of cdc2 associated with a characteristic set of cellular proteins, none of which appears to be cyclin A or cyclin B. None of the antibodies precipitated a histone-H1 or casein-kinase activity, although an activity which phosphorylated some of the coprecipitated proteins was coprecipitated with the group 2 Mab. These novel Mab did not interfere with the association of cdc2 with cyclin A in vitro and efficient immunoprecipitation of a panel of cdc2 mutant proteins suggests that the target epitopes may not involve amino acid residues essential for currently known cdc2 functions. The results of the present study provide evidence for the existence of additional forms of the cdc2 protein in exponentially growing human cells, distinct from both the monomeric and the cyclin-bound cdc2 identified so far.

Animals↗

PubMed1992

The surface treatment of polypropylene molds and its effect on the quality of cast contact lenses.

An investigation of the surface by XPS photoelectron spectroscopy has shown that the process of production of cast contact lenses based on poly(2-hydroxyethyl methacrylate-co-diethyleneglycol methacrylate) is accompanied by mass transfer at the lens-mold boundary. This phenomenon, which impairs the compatibility of the lens during its application, can be considerably suppressed by employing a suitable surface modification of polypropylene molds. The surface treatment consisting in the oxidation of the mold surface by an AC corona discharge in the oxygen atmosphere increases hydrophilicity of the material, thus facilitating separation of the lens from the mold. The results of the XPS study were also confirmed microscopically by employing the SEM method.

Contact Lenses, Hydrophilic↗

PubMed1992

[Surgical treatment of endocrine orbital disease. Indications, methods,results].

Surgical removal of the thyroid gland in Graves-Basedow's disease has, beyond doubt, also a major effect on endocrine orbitopathy. After total or near-total removal of the thyroid gland after three months a slighter deterioration or even ameloriation of ocular protrusion is found, contrary to the effect of subtotal thyroidectomy. There exists a significant correlation between the volume of the residual gland evaluated according to 24 h-uptake of 131I, and between the regression of the protrusion (r = 0.385, p < 0.01). Total or near-total thyroidectomy alone even in the absence of other therapeutic methods leads after 1 to 4 years to an average regression of the protrusion by 1 mm which matches the results of prednisone treatment, if the latter is used as the sole treatment. Orbital decompression by the modified method of Ogura and Walsh led in patients treated concurrently with prednisone and thyroidectomy to improvement of the visual acuity on average by 50% (from the range of 0.008 to 0.33 to values from 0.4 to 1.0) and to regression of the protrusion on average by 3.3 mm. When determining the time of operation of the oculomotor muscles, in addition to the unchanged ocular finding also the echographic picture in sectorial visualization proves useful.

Exophthalmos↗

PubMed1991

p53 protein alterations in human testicular cancer including pre-invasive intratubular germ-cell neoplasia.

Expression of the p53 oncoprotein was examined in a wide range of primary human testicular germ-cell tumours using a new mouse monoclonal antibody (MAb) BP53-11 raised and characterized in this study, in parallel with a polyclonal rabbit antiserum CM-1. Immunohistochemistry on paraffin sections showed positive nuclear reaction in at least a fraction of malignant cells in 90 (84%) out of 107 cases studied. Aberrant accumulation of the p53 protein was found among testicular tumours of all major histological types, although generally a higher percentage of positive cases and a higher proportion of p53 over-expressing nuclei within individual lesions was observed in embryonal carcinomas when compared with seminomas. The typical heterogeneous staining pattern characteristic of histological specimens was also found in a cultured cell line derived from a human embryonal carcinoma. In contrast to immunohistochemically undetectable levels in normal testes and morphologically normal tissue areas in the tumour-bearing testes, the accumulation of the p53 protein was clearly identified in a high proportion (59% of cases) of the pre-invasive lesions with positive atypical intratubular germ cells often found in the tissue adjacent to invasive tumours. Altered expression of the p53 protein is therefore a unifying feature of the majority of invasive male germ-cell tumours and the change resulting in high levels of p53 appears to be a relatively early step in the human testicular cancer pathogenesis.

Antibodies, Monoclonal↗

PubMed1991

Phyllogenetically conserved epitopes of the keratin 8 polypeptide recognized by a novel set of monoclonal antibodies.

In an attempt to raise a set of monoclonal antibody (MAb) probes for the study of biology and diagnostic value of human keratin No. 8, a series of hybridomas was prepared and their characteristics investigated by immunohistochemistry and immunoblotting. The polypeptide specificities of individual MAbs ranged from monospecificity for keratin No. 8 (MAbs C-15, C-23, C-36, C-43, C-47, C-51, and C-61) up to the "pan-keratin" MAbs C-11 and C-66 recognizing a broad range of keratins. The target epitopes of the remaining 4 MAbs (C-10, C-22, C-50, C-69) appear to be shared by various pairs of keratin polypeptides. The immunohistochemical investigation of tissues and/or cultured cells from 10 animal species revealed considerable variability of the interspecies crossreactivity of individual MAbs. The target epitopes of 5 MAbs appear to be phyllogenetically conserved from man to Xenopus, 6 of 12 MAbs tested show reactivity with several mammalian species (but not chicken or Xenopus) and the MAb C-15 reacts with human and sheep keratin only. The data obtained demonstrate that at least 9, and possibly as many as 12, nonidentical epitopes of the human keratin 8 polypeptide can be distinguished by this set of antibodies. The results of the present study suggest that our MAbs represent a significant contribution to the list of reagents applicable in both research of intermediate filament (IF) biology and diagnostic histopathology.

Animals↗