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Biomedical subjects

M Bartkowiak

Publications and source records attributed to M Bartkowiak.

16 recordsLinked to original sources
PubMed2004

Interfacial energy of the superfluid 3He a-B phase interface in the zero-temperature limit.

We have measured the surface energy of the interface between the A and B phases of superfluid 3He in the low temperature limit at zero pressure. Using a shaped magnetic field, we control the passage of the phase boundary through a small aperture. We obtain the interphase surface energy from the over- or undermagnetization required to force the interface through the aperture in both directions, yielding values of the surface tension and the interfacial contact angle. This is the first measurement of the interfacial energy in high magnetic fields and in the zero-temperature limit.

Journal Article↗
PubMed2000

Primary and secondary nucleation of the transition between the A and B phases of superfluid 3He

We have studied nucleation in superfluid 3He across the A-B phase transition driven by a magnetic field, in a controllable environment at very low temperatures. Both B-->A and A-->B secondary nucleation appear to be governed by the survival of pockets of the new phase trapped at surfaces. We find that, at fields near B(AB), primary A-->B nucleation cannot be triggered by ionizing or neutron irradiation even at very high intensities. In our cell primary A-->B nucleation can only be triggered externally by mild mechanical shock.

Journal Article↗
PubMed1999

Defect-mediated condensation of a charge density wave

Symmetry, dimensionality, and disorder play a pivotal role in critical phenomena. The atomic imaging capabilities of the scanning tunneling microscope were used to directly visualize the interaction between charge density oscillations and lattice defects in a two-dimensional charge density wave (CDW) system. Point defects act as nucleation centers of the CDW, which, as the temperature is lowered, results in the formation of pinned CDW domains that are separated by atomically abrupt charge boundaries. Incomplete freezing of substitutional disorder at low temperature indicates a novel CDW-mediated hopping of pinning centers.

Journal Article↗
PubMed1999

Endothelin-1 is involved in plasma mediated stimulation of neutrophil adherence during coronary artery bypass grafting.

OBJECTIVE: Myocardial ischaemia followed by reperfusion during coronary artery bypass grafting (CABG) is known to result in the activation of polymorphonuclear neutrophils (PMN). The activation of PMN during ischaemia/reperfusion may be a result of their direct contact with activated endothelial cells and/or an effect of stimuli released from ischaemic myocardium. Increased expression of adhesion molecules on the PMN surface, after activation, leads to coronary capillary plugging with a subsequent decrease in blood flow. The purpose of the study was to evaluate plasma-mediated stimulation of PMN adhesion during CABG and to verify if endothelin-1 (ET-1), known to be a potent stimulus for PMN, is involved in stimulation of neutrophils adhesion mediated by integrins. METHODS: Coronary sinus, peripheral artery and peripheral venous plasma samples were taken from 11 patients undergoing coronary surgery before aortal cross-clamping, at the beginning of reperfusion and 30 min thereafter. PMN isolated from five healthy volunteers were incubated with the plasma (20 samples per patient) in the presence of saline or a specific ET-1 receptor blocker, and PMN adherence to a microtiter plate covered with a monoclonal antibody against CD 18 antigen (beta-subunit of the integrin family of adhesion molecules) was evaluated. RESULTS: We have observed a significant increase in adhesion of PMN incubated in the presence of saline with the plasma taken from coronary sinus at the beginning of reperfusion (7.79+/-1.64% of adhering cells) as compared with plasma obtained before aortal cross-clamping from the same place (6.78+/-1.3%, P = 0.04) and from peripheral artery at the beginning of reperfusion (6.64+/-1.1%, P = 0.04, means +/- SEM). ET-1 receptor blocker, significantly decreased stimulation of PMN adhesion by coronary sinus plasma obtained at the beginning of reperfusion (6.7+/-1.51%, P = 0.02). Plasma levels of ET-1 (ELISA) in the samples taken from coronary sinus at the beginning of reperfusion, were higher than in samples obtained before myocardial ischaemia or 30 min after reperfusion. CONCLUSIONS: We conclude, that soluble stimuli capable of stimulation of PMN adhesion are released following myocardial ischaemia during CABG and ET-1 may be involved in PMN stimulation.

Adult↗
PubMed1995

[Activation of T lymphocytes and severity of atopic bronchial asthma in children].

Recent studies point out to the role of activated T lymphocytes in the pathogenesis of bronchial asthma. We analyzed (1) T subpopulations and (2) expression of the cell surface activation markers (the light chain of interleukin-2 receptor (IL-2R) and HLA-DR antigen) in the peripheral blood of 36 children with stable atopic asthma and 10 non-atopic control subjects. Flow cytometry and double phenotyping with monoclonal antibodies conjugated with fluorescein and phycoerythrin were used. The results of these studies were correlated to the degree of asthma severity. We found no differences between the two evaluated subgroups (severe asthma--AC and moderate asthma--AU) in the percentage of T cells with CD3 and CD4 antigen. In the severe asthma subgroup there were the following differences as compared with those from control subjects: decrease of the percentage of CD8+ lymphocytes (p < 0.01) and the increase of activated cells expressing IL-2R (p < 0.001) and HLA-DR (p < 0.001). Differences in the expression of activation markers were more pronounced in the CD4+ subpopulation (CD4+/IL-2R, p < 0.001 and CD4+/HLA-DR+, p < 0.001), while they were less visible, but still significant, in the CD8+ cells (CD8+/IL-2R+, p < 0.01 and CD8+/HLA-DR+, p < 0.05). When comparing the results in severe asthma subgroup with those in moderate asthma, significant elevation was found in CD4+/IL-2R+ (p < 0.03), CD4+/HLA-DR+ (p < 0.05) and CD8+/IL-2R+ (p < 0.03) double positive cells. These observations may indicate a role of activated T lymphocytes, CD4+ and CD8+, in the pathogenesis of atopic bronchial asthma in children and existence of prolonged activation factors in chronic severe asthma.

Adolescent↗
PubMed1995

[Thyroid gland function in neonates with transient hyperthyrotrophinemia from a region of slight iodine deficiency].

The aim of this study was to evaluate thyroid gland function in neonates and babies with transient hyperthyrotrophinemia during the first twelve months of life in an attempt to establish the causes of this condition in neonates born in a region of slight iodine deficiency. Thirty-eight newborns were screened. Clinical observations and measurements of serum T3, T4, TSH levels as well as urinary iodine were conducted for one year (at the age of 2 weeks, 3-4 months, and after one year of life). The screened children showed significantly higher values of T4 (p < 0.001) in comparison with the reference value in successive follow-up examinations. High T4 values may result from an increased TBG concentration in serum, and its level should be determined in the analysed material. Other hormonal values normalized after the second weak of life. Iodine deficiency was found in 80% of the children. Our assessments concerning the causes of transient hyperthyrotrophinemia conform with previous findings. It was established that the most common causes are iodine deficiency and maternal thyroid disease. None of the screened children had goitre somatic anomalies or delayed psychomotoric development did not appear more frequently than in the general pediatric population.

Female↗
PubMed1995

[Food allergy in pathogenesis of chronic abdominal pain in children].

Food allergy has been implicated lately in the etiopathogenesis of abdominal pain in children, with particular attention pain to gastritis and/or duodenitis. The aim of the study was to analyse the cause-and-effect relationship between chronic abdominal pain in children, endoscopic and histopatological picture, and food allergy, as well as to evaluate the applied elimination diet and/or antiallergic treatment on the improvement of both the clinical status and endoscopic picture. In 71 children gastrofiberoscopic examinations, food skin tests, and specific and total IgE allergen serum tests were performed. In the majority of examined children one could observe an improvement of clinical status and of the endoscopic-histopatological picture of the stomach mucous membrane after application an elimination diet and/or treatment with sodium cromoglycate.

Abdominal Pain↗
PubMed1993

The results of epidemiological studies concerning iodine deficiency and goiter in Poznań Region (Poznań coordinating center).

The studies concerning iodine deficiency and occurrence of goiter, being a fragment of the program covering different parts of Poland, included 2620 children of age between 7 and 12 years attending randomly chosen schools situated in towns and villages of Poznań, Pila, Leszno, Konin, Kalisz, Bydgoszcz and Zielona Góra districts. Among the children studied, 1009 children (522 boys and 487 girls) attended town schools, and 1611 (774 boys and 837 girls) country schools. All children were subjected to anamnesis by using a standard questionnaire. Also physical examination of the thyroid aimed at the evaluation of size and morphology of the gland was carried out by palpation (according to the obligatory WHO scale) and by ultrasonography. Urine samples were taken from the majority of children for the determination of urinary excretion of iodine. In 736 (28.1%) of the studied children an enlargement of the thyroid was found. Among these children 253 are inhabitants of towns (this number represents 27.8% of all urban children studied) and 483 are inhabitants of villages (30% of all rural children studied). In 92.7% of cases the goiter could be classified as type IB according to WHO and in 56 cases it was of nodular character. There was a clear relation between the incidence of goiter and the age of the children studied. Frequency distribution of goiter in the individual age groups was as follows: for urban children--21.8% in age group of 7-8 years, 23.5% in age group of 9-10 years and 29.7% in age group 11-12 years, and for rural children the corresponding values were 21.1%, 30.2% and 38.2%. Mean urinary iodine excretion was 96 micrograms/L (median 84 micrograms/L) for urban children, and 87 micrograms/L (median 64 micrograms/L) for rural children. Among 2620 answers concerning the use of iodized salt in the household, only 980 (37.1%) were positive. In towns, the use of iodized salt declared about 41% of families and in villages about 35%. Altogether, among 736 cases of goiter, 464 are children not using iodized salt. Only in 272 cases goiter appeared despite the use of iodized salt. The data concerning family occurrence of goiter and the type of iodized salt used can be treated as approximate because of subjective character. According to the results obtained, the region covered by the study falls according to the WHO and ICCIDD classification to the category of an area of mild iodine deficiency requiring more intensive iodine prophylaxis.

Child↗
PubMed1992

[Azoles. 34. Nitroimidazole derivatives and their antibacterial and fungicidal action].

Nitroimidazole derivatives 4a-4c, 5a-5c, 8a-8c and 9a-9c were synthesized by treating 4,5-dinitro- and 2-methyl-4,5-dinitroimidazole (1,2) or their silver salts [1.Ag,, 2.Ag) with chlorosubtituted phenacyl bromides 3a-3c, diethyl sulphate or ethyl iodide, allyl iodide and ethyl chloro-, azo- or bromoacetate. 2,4(5)-dinitroimidazole (10) has been converted to the 2,4-dinitroimidazole derivative 10a by the action of ethyl bromoacetate in the presence of sodium ethylate. A modified method for the synthesis of 6a and 6b has been described. 7a and 7b have been obtained by a known method. Some of the newly synthesized nitroimidazole derivatives show antibacterial and fungicidal activity.

Anti-Bacterial Agents↗