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Biomedical subjects

J Jankowski

Publications and source records attributed to J Jankowski.

At least 73 records · Page 4Linked to original sources
PubMed1998

Mediation of the vasoactive properties of diadenosine tetraphosphate via various purinoceptors.

OBJECTIVE AND METHODS: The vasoactive properties of P1,P4-diadenosine tetraphosphate (Ap4A) were studied by measuring the effects of perfusion pressure of a rat isolated perfused kidney. RESULTS: The vasoconstrictive response to Ap4A was mediated to a large extent to a P2X receptor which could be shown by inhibition with pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid tetrasodium. The remaining vasoconstriction of Ap4A could be blocked by a 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective A1 receptor antagonist In raised tone preparation Ap4A evoked vasodilation when P2 receptors were blocked by suramin. The dilation was not mediated by a P2Y receptor as the effect could not be blocked by suramin. CONCLUSION: Ap4A induces vasoconstriction via A1 and P2X receptors and vasodilatation via an unidentified receptor which is not a P2Y receptor. Ap4A may play an important role in kidney perfusion and, thus, in blood-pressure control.

Adenosine Triphosphate↗
PubMed1998

Characterization of dimethylguanosine, phenylethylamine, and phenylacetic acid as inhibitors of Ca2+ ATPase in end-stage renal failure.

The activity of the plasma membrane Ca2+ ATPase of chronic renal failure patients is decreased by circulating inhibitors yet to be characterized. In this study, inhibitors of Ca2+ ATPase were isolated from ultrafiltrate of patients with end-stage renal failure. They were identified as dimethylguanosine, phenylethylamine, and phenylacetic acid by chromatography and mass spectrometry. Ca2+ ATPase activity was measured spectrophotometrically as the difference in hydrolysis of ATP in the presence and absence of Ca2+ with different concentrations of ATP and the isolated substances. All of the identified compounds are sufficiently lipophilic to penetrate the blood-brain barrier and to accumulate in cerebral tissue. The inhibitory effects of these agents were additive. The apparent K(m) values for ATP and Ca2+ were not altered by these substances, suggesting a noncompetitive mechanism of inhibition. In plasma of healthy subjects, the substances were not detectable. The Ca2+ ATPase inhibitors identified may play a role in the pathophysiology of end-stage renal failure and, potentially, in monitoring toxic effects on cellular Ca2+ metabolism in renal failure.

Adult↗
PubMed1998

Altered cadherin and catenin complexes in the Barrett's esophagus-dysplasia-adenocarcinoma sequence: correlation with disease progression and dedifferentiation.

The maintenance of adult tissue architecture is largely dependent on the function of cadherins. E-cadherin is expressed in most epithelia, although it may be co-expressed with P-cadherin in basal layers of stratified epithelia. Adhesive function of cadherins relies on interactions with catenins. Many reports have characterized reduced expression of cadherins and catenins in tumors, including those of the gastrointestinal tract. This study aimed to characterize expression of E- and P-cadherins, and the catenins, in the progression of Barrett's esophagus to adenocarcinoma. Immunohistochemical analysis and Western blotting were performed on paraffin-embedded and fresh-frozen tissue using antisera to the selected cadherins and catenins. The results of this study have shown inappropriate expression of cadherins and catenins in neoplastic Barrett's mucosa. There was a significant reduction of E-cadherin expression as the Barrett's metaplasia-dysplasia-adenocarcinoma sequence progressed (P < 0.01). In contrast, P-cadherin, expressed in basal layers of squamous esophagus, was usually absent from Barrett's and dysplasia but was expressed in 17 of 24 carcinomas, especially at the advancing tumor edge. Reduced expression of catenins was also seen, but in some specimens, immunoreactivity was observed in neoplastic nuclei, suggesting mediation of a nuclear function such as transcriptional regulation.

Adenocarcinoma↗
PubMed1998

[Occupational problems from exposure to roentgen rays].

The authors analysed methodological problems concerning the use of film dosimetry in the evaluation of annual doses received by workers exposed to X-radiation. This is mainly related to nonlinearity of the optical density of films dependent on the dose and the photon energy. The set of four filters solved these problems. The evaluation of occupational exposure among workers being in contract with X-radiation sources in 1996 as well as the analysis of data on occupational exposure followed since 1966 are presented.

Film Dosimetry↗
PubMed1998

[Evaluation of effective doses received by patients, during selected types of diagnostic radiation, in Wrocław].

A theoretical method for evaluating effective doses (mSv) received by patients during selected X-ray diagnostic examinations is presented. The measurements of exposure doses (mGy) performed in 35 radiological and diagnostic units, randomly selected in the city of Wrocław and in the Wrocław voivodship, were taken as the basis for calculations. Effective doses (mSv) were reckoned using conversion coefficients whose values were read from the tables given in another paper (3). The results obtained were compared with similar studies carried out in Poland, UK and Finland as well as with recommended values. The comparison between measured and recommended doses indicated that in the Wrocław voivodship doses received during X-ray examinations with defined conversion coefficients were generally lower than those recommended. The only exception were doses received by patients during X-ray chest examinations with the difference of 64% against recommended doses. It is significant in this respect that chest X-ray examinations constitute a considerable proportion of all kinds of examinations taken among patients in this region (136 of the total 608 examinations in 1995-22.4% (1). The mean value of the effective dose received by patients during diagnostic X-ray examination in the Wrocław voivodship did not exceed 1 mSv.

Environmental Exposure↗
PubMed1998

Identification of oxidized low-density lipoprotein in human serum by NMR spectroscopy.

1. In this study we compared the 500 MHz 1H-NMRs from native and oxidized low-density lipoproteins. 2. The measurements revealed a characteristic pattern of three resonances in spectra from oxidized, but not from native low-density lipoprotein at 1.17 p.p.m., 1.18 p.p.m. and 1.20 p.p.m. (relative to 3-trimethylsilyl-[2,2,3, 3-2H4]-propionate).3.A quantitative comparison between these resonances in sera from patients with coronary heart disease and healthy control subjects revealed that the intensity was significantly higher in patients with coronary heart disease (1.17 p.p.m.: 0.026+/-0.014 versus 0.015+/-0.019; 1.18 p.p.m.: 0.032+/-0.011 versus 0.017+/-0.021; 1.20 p.p.m.: 0.030+/-0.066 versus 0.010+/-0.005; P<0.05 compared with healthy control subjects for each resonance).4.Fractionation of sera from patients with coronary heart disease revealed that the resonances equal to those obtained from experimentally oxidized low-density lipoprotein are indeed caused by the low-density lipoprotein fraction of the sera.5. When the NMRs from sera were calibrated with oxidized low-density lipoprotein prepared by Cu2+ oxidation, a concentration of 66.5+/-28.6 microgram/ml and 36.3+/-23.7 microgram/ml (P<0.05) was estimated in patients with coronary heart disease and healthy subjects respectively. Elevated levels of oxidized low-density lipoprotein also occurred in those patients with normal serum concentrations of total low-density lipoprotein.6. The study shows a simple method to measure oxidized low-density lipoprotein in human serum and may gain interest to assess the cardiovascular risk factor profiles more completely.

Case-Control Studies↗
PubMed1998

[Absorption and dispersion of ultraviolet radiation in human skin].

The study was carried out in a group composed of 48 men. The linear coefficient and linear coefficient of dispersion of ultraviolet radiation (UVR) in the skin was measured for different wavelengths. The mean values were determined for four types of the skin in both ultraviolet A (UVA) and ultraviolet B (UVB) ranges from 280 to 400 nm. The skin ability to absorb UVR decreases rapidly with decreasing wavelength. At wavelength of 280 nm, the coefficient of absorption changed within the range from 105 cm-1 (skin type II) to 160 cm-1 (skin type V), however, at wavelength of 400 nm it accounted only for 20 cm-1. A reciprocal relationship for scattering was found. The coefficient of dispersion changed within the range from 3.5 cm-1 at wavelength of 280 nm to 12 cm-1 at wavelength of 400nm. The mechanism based on absorption predominated at a shorter wave range (UVB), while at a longer range (UVA) the scattering mechanism was more efficient.

Adult↗
PubMed1998

[Prognosis of the skin UV-incidence increase in Poland].

The degradation of the ozone layer causes a real menace to human health. One of the most dangerous effects is the possibility of evoking skin cancer by the intensified UV-radiation level. The authors analysed the influence of ongoing changes on the increase in skin cancer cases in Polish conditions. Following the analysis, a 16-per cent increase in morbidity can be anticipated within the next decade.

Adult↗
PubMed1997

Effect of diadenosine polyphosphates on Ca2+ ATPase activity.

Diadenosine tri-, tetra-, penta-, and hexaphosphate (Ap3A, Ap4A, Ap5A and Ap6A) have been described as having various effects on vascular tone depending on the number of phosphate groups. This study examined the effect of diadenosine polyphosphates on Ca2+ ATPase activity. The activity of the enzyme was measured spectrophotometrically as the difference in hydrolysis of ATP in the presence and absence of Ca2+ with various concentrations of ATP and diadenosine polyphosphates. The diadenosine polyphosphates increased the activity of the Ca2+ ATPase. The effect tended to be stronger with Ap5A and Ap6A than with Ap3A and Ap4A in the order of potency: Ap3A approximately AP4A < Ap5A approximately AP6A. The stimulatory effect of diadenosine polyphosphates was not competitive with that of ATP, suggesting an allosteric activation of Ca2+ ATPase by diadenosine polyphosphates. This effect may be physiologically relevant for limiting the increase in cytosolic free Ca2+ concentration elicited by diadenosine polyphosphates by receptor activation and modulating Ca2+ ATPase function under resting conditions.

Adenosine Triphosphate↗
PubMed1997

Diadenosine polyphosphates' action on calcium and vessel contraction.

The effects of the endogenous, platelet-derived vasoactive compounds, diadenosine tetraphosphate (AP4A), diadenosine pentaphosphate (AP5A), and diadenosine hexaphosphate (AP6A) on the vasoconstriction of isolated rat renal resistance vessels and rat aortic strips were measured using a vessel myograph. In addition, the effects of AP4A, AP5A, and AP6A on the cytosolic free calcium concentration ([Ca2+]i) were evaluated in cultured rat vascular smooth muscle cells (VSMC) using the fluorescent dye technique. Diadenosine polyphosphates dose-dependently increased the force of renal resistance vessels and isolated aortic strips. The administration of 10 mumol/L AP4A, AP5A, or AP6A significantly increased the force of isolated renal resistance vessels by 3.48+/-0.43 mN (n = 8), 2.14+/-0.40 mN (n = 12), or 2.70+/-0.31 mN (n = 11, each P < .01 compared with resting tension), respectively. The administration of 10 micromol/L AP4A, AP5A, or AP6A significantly increased the force of isolated aortic strips by 2.45+/-0.97 mNewton (n = 10), 2.70+/- 0.30 mN (n = 6), or 1.48+/-0.20 mN (each P < .01 compared with resting tension), respectively. The administration of 10 micromol/L AP4A, AP5A, or AP6A significantly increased [Ca2+]i in VSMC to a peak concentration of 314+/-60 nmol/L (n = 6), 247+/-25 nmol/L (n = 15), or 332+/-100 nmol/L (n = 5), respectively (each P < .01 compared with resting value). Both the diadenosine polyphosphate-induced vasoconstriction and [Ca2+]i increase was significantly reduced in the absence of extracellular calcium or after administration of a specific inhibitor of P2 purinoceptors. It is concluded that diadenosine polyphosphates increase [Ca2+]i and hence cause vessel constriction.

Animals↗
PubMed1997

[Selected technical aspects of roentgen diagnostic equipment from the view of quality control requirements].

Thirty randomly sampled X-ray units were thoroughly investigated in order to compare their real parameters with values given by manufacturers. The following parameters were measured: effective voltage (kVef), peak voltage value (kVp), anodic current intensity (mA), exposure time and current intensity (mAs), exposure time (mS), repeatability of effective and peak voltage, and repeatability of radiation dose (mGy). The magnitude of the focus and perpendicularity of radiation beam were also checked. The majority of study parameters differed considerably. In some instances the difference between real values and those indicated on X-ray units reached even several dozen per cent.

Electricity↗
PubMed1997

[Evaluation of patient exposure to radiation during x-ray diagnostic examinations (in selected health service centers in the city of Wrocław and in the province of Wrocław)].

In 35 x-ray laboratories, randomly selected, in the city of Wrocław an in the voivodship, the following measurements were performed: -exposure doses (mGy) for different kinds of x-ray examinations, -exposure doses (mGy) for examinations employing conventional intensifying cassettes and cassettes equipped with intensifying screens of rare earths, -basic exposure parameters, ie high voltage (kV), anodic current intensity (mA), and exposure duration. An average number of exposure per one examination was also defined. The values of standard deviation (SD) for doses measured and for exposure parameters were identified. The doses were compared with the values recommended in "Basic Safety Standards for Protection Against Ionizing Radiation" (IAEA, Safety Series No 115). Two differences were discussed between the values measured and those recommended, particularly in exposures when conventional cassettes were used. The assessment of exposure parameters for the same x-ray examinations performed in different laboratories pointed to a lack of any analogy between the results. It bears witness to the fact that x-ray equipment is very much diversified, and that subjective factors play a significant role.

Air Pollutants, Radioactive↗
PubMed1997

The effect of depletion of the earth ozone layer on the human health condition.

Development of economic human activity has caused many harmful side effects which constitute an important danger for the biological life of our planet. This review discusses some aspects of the atmospheric changes and their influence on UV radiation reaching a man. The ozone-layer depletion is the result of emissions to the atmosphere chemical substances containing chlorine and bromine. Ozone, which absorbs the solar ultraviolet radiation, is a basic bio-protective filter. Degradation of the atmospheric ozone layer leads to increase of UV-level in our environment. The harmful effects of UV-radiation on live organisms constitute a danger for health of the whole human population. There is no doubt that cumulative exposure to UV radiation is important in the aetiology of skin cancer. A strong cataractogenic effect of UV radiation has been also evidenced. It is also known that the increase of UV radiation may be capable of activating viruses and reduce immunological response. The recent and predicted increase in these menaces are discussed.

Atmosphere↗
PubMed1996

[Use of low temperature methods with optically stimulated luminescence for measuring ionizing radiation doses].

A new method of cooled optically stimulated luminescence (COSL) based on CaF2:Mn crystals has become the subject of numerous studies carried out by the Pacific Northwest Laboratory in the United States. The method has developed and expanded the feasibility of measuring ionizing radiation doses based on a classical phenomenon of thermoluminescence. Much greater sensitivity of the new method allows to measure doses of 10 microR order. A manifold reading of a given dosimeter is also feasible. That facilitates the elimination of doubtful readings. The reading of a dose from the dosimeter and cleaning for its reuse is performed in temperatures not higher than room temperature. Therefore, dosimeters in the form of powder embedded in a plastic matrix which imitates live tissue, can be easily used, whereas thermoluminescence method would cause melting of a dosimeter during its reading. The authors made an attempt to get acquainted the reader with extremely interesting method for measuring ionizing radiation doses.

Radiation Dosage↗
PubMed1996

[Evaluation ultraviolet radiation penetration into human skin. II. experimental studies].

Direct reflections of ultraviolet (UV) radiation (280-400 nm wavelength) from the human skin were characterised for different types of individuals. On the ground of this characteristics, the total UV reflection coefficient in this range was estimated. A new, noninvasive method for measuring a linear absorption and dispersion coefficient of UV radiation in skin layer was proposed. It is based on the measurement of radiant flux dispersed inside the skin cover during its radiation by a beam with a given profile. The dispersive flux is measured beyond the light zone. The absorption and dispersion coefficients can be calculated according to formulas developed previously and published in part I--"Theoretical analysis". Preliminary measurements of the above mentioned parameters were performed for different types of individuals.

Absorption↗
PubMed1996

[Sources of x-rays in school].

Exposure of teachers of physics to x-radiation emitted by instruments which are used for demonstrating rarefied gas discharges during physics lessons at secondary schools is discussed. The measurements performed provide an explicit evidence that an effective, anual exposure dose under the most unfavourable conditions does not exceed admissible levels according to Polish regulations pertaining to persons non-occupationally exposed to ionizing radiation.

Environmental Monitoring↗
PubMed1996

[Consequences of the reactor breakdown at Chernobyl 10 years after the catastrophe].

An international conference organised by the European Commission the International Agency of Atomic Energy and the World Health Organization took place on 8-12 April 1996. The conference aimed at evaluating the consequences of the nuclear reactor break down in Chernobyl which have far been identified. The author presents the general outcome of the conference. The article has been prepared on the basis of the conference materials, discussions held during individual sessions and original publications devoted to this subject. All the materials are in the author's possession and can be made available to those interested. The work will be reprinted in extenso in one of the coming issues of the International Journal of Occupational Medicine and Environmental Health.

Environmental Monitoring↗