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Biomedical subjects

K Blazek

Publications and source records attributed to K Blazek.

At least 19 recordsLinked to original sources
PubMed2006

Prolactin delays hair regrowth in mice.

Mammalian hair growth is cyclic, with hair-producing follicles alternating between active (anagen) and quiescent (telogen) phases. The timing of hair cycles is advanced in prolactin receptor (PRLR) knockout mice, suggesting that prolactin has a role in regulating follicle cycling. In this study, the relationship between profiles of circulating prolactin and the first post-natal hair growth cycle was examined in female Balb/c mice. Prolactin was found to increase at 3 weeks of age, prior to the onset of anagen 1 week later. Expression of PRLR mRNA in skin increased fourfold during early anagen. This was followed by upregulation of prolactin mRNA, also expressed in the skin. Pharmacological suppression of pituitary prolactin advanced dorsal hair growth by 3.5 days. Normal hair cycling was restored by replacement with exogenous prolactin for 3 days. Increasing the duration of prolactin treatment further retarded entry into anagen. However, prolactin treatments, which began after follicles had entered anagen at 26 days of age, did not alter the subsequent progression of the hair cycle. Skin from PRLR-deficient mice grafted onto endocrine-normal hosts underwent more rapid hair cycling than comparable wild-type grafts, with reduced duration of the telogen phase. These experiments demonstrate that prolactin regulates the timing of hair growth cycles in mice via a direct effect on the skin, rather than solely via the modulation of other endocrine factors.

Animals↗
PubMed1999

Subchronic preexposure to carbon monoxide modifies heart response to a combined CO + isoproterenol challenge in rats.

The effect of repeated exposure to carbon monoxide (CO) on the response of middle-age rats to an acute CO exposure combined with a low dose of a sympathomimetic agent was studied. A group of 12 rats (male albino, Wistar, age 9 months) without ECG abnormalities was divided into two subgroups matched for weight, heart rate and ECG: one subgroup was exposed to 500 ppm CO for 6 h/d, 5 d/w, for 6 weeks (peak COHb 31.5%, SD 3.5); the other one (controls) was exposed to fresh air. Two or three days after the last exposure both groups underwent combined challenge with 0.025 mg/kg isoproterenol s.c. and 90 minute exposure to CO in a concentration increasing from 500 to 1500 ppm; ECG was recorded continuously. The hearts were examined morphometrically and histologically. The CO-preexposed subgroup had, as compared to controls: 1) significantly higher blood hemoglobin (by 25%), erythrocyte count (by 28%) and volume (by 6%), and hematocrit (by 33%); 2) the same peak COHb; 3) lower basic heart rate and an earlier decrease after isoproterenol, 4) significantly smaller increase in ECG abnormalities and arrhythmias after isoproterenol and during CO exposure; 5) nonsignificantly higher heart weight indexes; 6) a nonsignificantly lower score of histological abnormalities. The global score of ECG pathology during CO exposure (abnormal pattern or arrhythmia) correlated best (multiple corr. coef. >0.9) with end-exposure free (non CO bound) hemoglobin (negatively) and with mean heart rate during exposure (positively): the lower score in the preexposed subgroup was attributable primarily to the increased hemoglobin. Six-week intermittent CO exposure induced marked compensatory processes (hematological) but only a tendency to adaptational changes in the heart (by gross morphometry), and decreased the ECG response to CO+ isoproterenol challenge at the same COHb.

Animals↗
PubMed1997

Polymerase chain reaction for detection of guinea pig adenovirus.

Lack of in vitro cultivation methods has inhibited the development of rapid, reliable diagnostic procedures for adenovirus-associated necrotizing bronchopneumonia in guinea pigs. Because polymerase chain reaction (PCR) techniques are well established for human adenoviruses, primers for the amplification of guinea pig adenovirus DNA were evaluated. The DNA for PCR was purified from the lung tissue of spontaneously infected and healthy guinea pigs. Adenovirus DNA could only be detected in the lungs of the infected animals. Subsequent sequence analysis of PCR products revealed that the guinea pig adenovirus is a distinct adenovirus.

Adenoviridae↗
PubMed1997

Treatment of transplanted spontaneous rat T-cell leukaemia with local administration of recombinant murine interleukin-2.

Spontaneous rat CD4+CD8-T-cell leukaemia transplanted in syngeneic recipients served as an experimental model system for IL-2 therapy. As a source of IL-2, supernatants from in vitro cultured plasmacytoma cell line X63-m-IL2 secreting constitutively recombinant murine IL-2 were utilized. Administration of IL-2, s.c. to the vicinity of the tumour inoculum, suppressed tumour growth. The tumour-inhibitory IL-2 effects were time- and dose-dependent. When the treatment has started 10 days after the challenge with 10(4) leukaemia cells, IL-2 inhibitory effects on the lymphoma growth in situ were demonstrated by lower tumour weight combined with necrotic changes. No histological signs of lymphoma generalization were found in parenchymatous organs of IL-2-treated rats in contrast to the untreated controls. No histological or functional injuries to the kidneys due to IL-2 administration were found. The results of effector cell phenotyping demonstrated the kinetics of the CD4+/CD8+ ratio characterized by CD4+ T-cell depletion and resulting increase in the percentage of CD8+ PBL.

Animals↗
PubMed1997

Electron microscopic demonstration of the interaction of liposomes and cells in vitro.

We have investigated the interaction of liposomes with the continuous cell lines P388D1 and L-132 and mouse peritoneal macrophages. To distinguish the liposomes from other vesicular structures, we have used liposomes with incorporated protein G and gold. A heterogeneous mixture of multilamellar liposomes 30 nm up to 1000 nm in size has been employed. Samples were examined at different time intervals. We found differences in the uptake of liposomes with regard to size and rate. Cells of a P388D1 monolayer took up liposomes by endocytosis very early after addition of liposomes and the number of lysosomes in their cytoplasm increased. In L-132 cells, first a fusion occurred between liposomes and the cell cytoplasmic protrusions, in the cytoplasm of which the mitochondria had multiplied. Peritoneal macrophages phagocytosed mainly large multilamellar liposomes and the membranous system of Golgi apparatus was the most prominent structure in the cytoplasm. Phagocytosis in P388D1 and L-132 cells was noted sporadically as late as 24 h after addition of liposomes to the cells.

Animals↗
PubMed1997

Electron microscopic demonstration of the penetration of liposomes through skin.

To verify the penetration of liposomes through skin, we have used liposomes with encapsulated protein G-gold conjugate in a gel vehicle. Skin samples were examined 2, 4, 24, 48, and 72 h after liposome application. Our findings show that the penetration of liposomes through skin depends mainly on their size. Liposomes up to 600 nm in diameter penetrate through skin rather easily, whereas liposomes 1000 nm and more in diameter remain interiorized in the stratum corneum. The main penetration of liposomes proceeds along the hair sheaths as indicated by larger amounts of free liposomes in the corium of guinea pigs.

Animals↗
PubMed1997

The effect of an antiphlogistic incorporated in liposomes on experimentally induced inflammation.

The antiphlogistic Ibuprofen incorporated in liposomes caused a decrease of the inflammatory edema induced by Carrageenan in the distal part of the rat's hind leg after both the intramuscular and percutaneous administration. The antiphlogistic effect of free Ibuprofen in the cream was weaker. Intramuscular administration of empty liposomes slowed down in the initial stages the development of inflammation and slightly diminished the size of edema.

Administration, Cutaneous↗
PubMed1994

Electron-microscopic demonstration of virus particles in acute lymphoblastic leukaemia in Sprague-Dawley rats.

Retrovirus-like particles were detected by the negative staining method in supernatants of lymph node and spleen cell suspensions prepared from Sprague-Dawley rats with spontaneous acute lymphoblastic leukaemia (ALL). Similar particles were found in supernatants of cell suspensions from a lymphoma that developed after inoculation of lymph node and spleen cell suspension prepared from animals with spontaneous ALL into the subcutis of Sprague-Dawley recipients. On ultrathin sections, budding forms of the virus particles were seen as a dot at the periphery of neoplastically transformed cells.

Animals↗
PubMed1993

Cytostatic effect of 9-(2-phosphonomethoxyethyl) adenine (PMEA). II. Lymphoblastic leukemia in Sprague-Dawley rats.

Two cases of spontaneous acute lymphoblastic leukemia in the inbred strain of Sprague-Dawley (Prague) rats have been observed. Since its reliable transplantability in syngeneic recipients was established, leukemic animals were used to test the cytostatic effect of PMEA. The treatment resulted in a significant prolongation of survival time of the treated animals. At the same time histological examination of PMEA-treated and untreated animals indicated that the drug effectively slows down the growth of lymphoma at the site of inoculation and inhibits the subsequent progression of tumor cells in the lung, liver, spleen and lymph nodes.

Adenine↗
PubMed1991

[Pathologic changes in the lungs of deer spontaneously infected with nematodes from the Protostrongylidae family].

Lungs of 30 animals of the red deer (Cervus elaphus hippelaphus) attacked by parasitic helminths were submitted to a histological examination, and the changes which were caused by the nematodes of Protostrongylidae family were estimated. The lungworm Varestrongylus sagittatus (Mueller, 1891) creates hatching tubercles of a dark-red or yellow-green and even ochre colour. The lobular catarrhal bronchopneumonia is a histological correlate. In hatching tubercles there are located adult nematodes, ova of 46 x 27 microns and larvae of the 1st stage. For the infection of the Elaphostrongylus cervi nematodes (Cameron, 1931), the typical changes are those of the character of disseminated interstitial pneumonia. In the pulmonary tissue affected in such a way, there are numerous haemorrhages often visible microscopically. In the capillaries of interalveolar septa there are ova of E. cervi that reach up to 83 microns in dependence on the degree of their development and in alveoli there are larvae of the 1st stage. Adults do not occur in lungs.

Animals↗
PubMed1990

Some aspects of the presence of surface--associated acid mucosubstances on larval Taenia saginata infecting suitable and unsuitable hosts.

The coat of acid mucosubstances occurring on the bladder surface was studied in Cysticercus bovis (larvae of Taenia saginata) developing in specific (cattle) and nonspecific (some other ruminants) intermediate hosts. In cysticerci developing in nonspecific intermediate hosts, this coat is absent or poorly developed even at the time when it is completely formed on the bladder surface of C. bovis from cattle. If the cysticercus develops up to the infective stage in a nonspecific intermediate host, it is usually localized outside the muscles: in the brain, lungs or liver. Its bladder is then also covered by a coat of acid mucosubstances. The absence or insufficient development of the protective coat on larvae in nonspecific intermediate hosts is explained by their early and strong tissue reaction.

Animals↗
PubMed1988

Cysticercus bovis: pinocytosis in the Cysticercus tegument.

The authors have found that pinocytosis occurs in the tegument of C. bovis from the fourth week after infection. Electron-lucid bladders surrounded by plasma membrane were encountered in the distal cytoplasm. The pinocytosis occurred in form of micropinocytotic bladders only in the bladder tegument but not in the scolex. The bladders appeared first in the superficial part of the distal cytoplasm. During the following periods of development of the larva they were dispersed in the whole distal cytoplasm and were found even in the processes of subtegumental cells and inside these cells near the heterolysosomes.

Animals↗
PubMed1986

Pathology of experimental Cysticercus bovis infection in the reindeer (Rangifer tarandus Linné, 1758).

In the present study, the tissue reaction of the brain, skeletal muscles and heart in experimental C. bovis infection of the reindeer is described. There is non-purulent cysticercal leptomeningites with formation of multinucleate symplasms in the cerebral meninges, and lymphocytic encephalitis in the superficial layers of the cerebral cortex. The tissue reaction around the morphologically differentiated cysticercus in the meningeal location is similar to that in muscle cysticercosis of cattle. In muscles and heart, larvae die very soon after infection and they are resorbed in the course of formation of fibroplastic granulation tissue around them. C. bovis reaches the infective stage in cerebral localization only. The authors suppose that this phenomenon is due to a certain degree of immunological tolerance in the brain.

Animals↗
PubMed1986

Some diagnostic, biologic and morphologic characteristics of Francisella tularensis strains isolated from the ticks Ixodes ricinus (L.) in the Prague agglomeration.

Four infectious agents were isolated from the ticks Ixodes ricinus (L.) collected in the recreational area and park-forest of Prague. On the basis of cultivation, staining, biochemical, serologic properties, pathogenicity for animals and histological tests they were identified as Francisella tularensis with the following features: they are short, gram-negative rods of approximate dimensions of 0.3 X 0.8 micron, growing in enriched media after 3-4 day incubation at 37 degrees C. They form small circular, at first transparent, later greyish turbid colonies with regular rims. They are little active biochemically. They are susceptible to streptomycin and some broad spectrum antibiotics. They react positively with tularemic serum, but in lower titres than those in which this serum reacts with standard antigen. The microbes are highly pathogenic for mice, guinea-pigs, young rats, in which a massive bacteriemia occurs before death, but they do not kill rabbits. They multiply well in chick embryo, but do not grow in cell or tissue cultures. The most important histologic changes were observed in liver and spleen of mice. No pathologic changes were found in brain, lungs, heart, kidneys. Necroses were found in liver and in their marginal zones the microbes were present. Conspicuous were changes in numerous hepatocytes which became enlarged due to microbial multiplication and finally transformed into "sacs" packed with microbes. Histological and electronoptical examination showed that these are intracellular parasites fringed with a light lytic zone. Discussed is the problem to what extent the properties of the isolated strains are typical of F. tularensis as well as the importance of their detection from the aspect of epidemiology and differential diagnostics.

Animals↗
PubMed1985

Pathology of the migration phase of Taenia hydatigena (Pallas, 1766) larvae.

The pathological picture of the migration phase of C. tenuicollis in pigs is characterized by a haemorrhagia within the liver parenchyma and under the liver surface. The haemorrhagia, which represents a migrational canal, is induced by the destruction of liver sinuses by migrating larvae. Approximately on day 10 p.i. a serofibrinous peritonitis occurs and free cysticerci appear in the exudate. On days 14-16 p.i. the exudative peritonitis may increase. The cysticerci are localized under the serosas or on them. On about day 10 p.i. even the pulmonary form of the disease may occur. On day 13 p.i. the cysticerci are present in the lumen of lung arteries or they migrate out of them. The changes in the lungs and on the pleura, as well as their dynamic changes, are identical with the changes in the liver and on the peritoneum. The period on days 21-24 p.i. is characterized by extensive synechiae of serosas and the cysticerci are firmly attached to the serosas. On day 35 p.i. the connective tissue adhesions persist and many of the cysticerci exhibit dystrophic changes or are dead and often already calcified. The wall of the pseudocyst, in which the cysticercus is situated, consists of the fibrocytes and serosa, and its cavity is not lined with endothelium, as it is the case in C. bovis and C. cellulosae.

Animals↗