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Biomedical subjects

A Kamińska

Publications and source records attributed to A Kamińska.

At least 19 recordsLinked to original sources

Diffusion equations for a Markovian jumping process.

We consider a Markovian jumping process which is defined in terms of the jump-size distribution and the waiting-time distribution with a position-dependent frequency, in the diffusion limit. We assume the power-law form for the frequency. For small steps, we derive the Fokker-Planck equation and show the presence of the normal diffusion, subdiffusion, and superdiffusion. For the Lévy distribution of the step size, we construct a fractional equation, which possesses a variable coefficient, and solve it in the diffusion limit. Then we calculate fractional moments and define the fractional diffusion coefficient as a natural extension to the cases with the divergent variance. We also solve the master equation numerically and demonstrate that there are deviations from the Lévy stable distribution for large wave numbers.

Journal Article↗

Congenital myopathy with tubular aggregates and tubulofilamentous IBM-type inclusions.

We report on a 16-year-old girl with a unique neuromuscular disorder characterised by progressive proximal muscle weakness and numerous tubular aggregates, intracytoplasmic, as well as intranuclear inclusions of the IBM type in her muscle biopsy. The clinical features of the presented case, as manifested by the early childhood onset of the disease, proximal weakness, lumbar hyperlordosis, and bilateral Achilles tendon contractures, were suggestive of congenital myopathy. To the best of our knowledge, the coexistence of tubular aggregates and tubulofilamentous inclusions of the IBM type in a child has never been described.

Adolescent↗

Stochastic equation for a jumping process with long-time correlations.

A jumping process, defined in terms of the jump size and waiting time distributions, is presented. The jumping rate depends on the process value. The process, which is Markovian and stationary, relaxes to an equilibrium and is characterized by a power-law autocorrelation function. Therefore, it can serve as a model of 1/f noise as well as of the stochastic force in the generalized Langevin equation. This equation is solved for noise correlations approximately 1/t ; the resulting velocity distribution has sharply falling tails. The system preserves memory about the initial condition for a very long time.

Journal Article↗

Simple jumping process with memory: transport equation and diffusion.

We present a stochastic jumping process, defined in terms of jump-size probability density and jumping rate, which is a generalization of the well-known kangaroo process. The definition takes into account two process values: after and before the jump. Therefore, the process is able to preserve memory about its previous values. It possesses a simple stationary limit. Its master equation is interpreted as the kinetic equation with variable collision rate. The process can be easily applied to model systems which relax to distributions other than Maxwellian. The case of a constant jumping rate corresponds to the diffusion process, either normal or ballistic.

Journal Article↗

Solving the Chapman-Kolmogorov equation for a jumping process.

A general solution to the Chapman-Kolmogorov equation for a jumping process called the "kangaroo process" is derived. A special case of algebraic dependences is discussed in detail. In particular, simple asymptotic formulas for probability distribution are presented. It is demonstrated that there are two different classes of limiting stationary distributions. An expression for the covariance is also derived.

Journal Article↗

Excitation energy transport and trapping in concentrated solid solutions of flavomononucleotide.

Excitation energy transport and trapping is studied for monomer-fluorescent dimer system of flavomononucleotide (FMN) in polyvinyl alcohol films (PVA). It is shown that the theory neglecting reverse energy transfer (RET) from dimers to monomers does not allow for the explanation of concentration quenching and concentration depolarization results presented herein. Much better agreement has been obtained using generalized energy transport theory in which fluorescent dimers are treated as imperfect traps for excitation energy. Such parameters like the dimer quantum yield and its emission anisotropy are estimated.

Dimerization↗

Congenital myopathy with abundant ring fibres, rimmed vacuoles and inclusion body myositis-type inclusions.

We report a 17-year-old girl with an unusual neuromuscular disorder characterised by slowly progressive proximal muscle weakness whose muscle biopsy showed multiple ring fibres and numerous rimmed vacuoles as well as intracytoplasmic and intranuclear inclusions of the inclusion body myositis-type. The clinical features of the presented case, manifested by the onset of the disease in early childhood, delayed motor development, short stature, lordosis and joint contractures were suggestive of congenital myopathy. The coexistence of ring fibres, rimmed vacuoles and inclusion-body myositis-type inclusions in a child with congenital myopathy has not been previously reported.

Adolescent↗

Hepatobiliary scanning in the diagnosis of biliary atresia.

Early diagnosis is vital in the neonatal cholestasis. The aim of this study was to assess the usefulness of hepatobiliary scanning in the diagnosis of biliary atresia. 33 hepatobiliary scannings performed in 30 children with cholestasis over the last two years were analysed. The mean age at the diagnosis was 6.6 weeks. The investigation was carried out with Multispect camera using intravenous infusion of 99mTc-MBrIDA. In 23 patients there was no passage of the radiolabelled substance into the intestinal tract. In 18 patients biliary atresia was diagnosed. One patient with a clinical suspicion of Alagille syndrome had two scannings performed at the interval of two weeks. In 1 child a common biliary tract cyst with total obstruction of extrahepatic biliary tree was diagnosed. In 18 children with biliary atresia the diagnosis was confirmed during the operation and Kasai procedure was performed. In 2 children the second scanning showed bile drainage. In 3 children intrahepatic cholestasis was diagnosed in addition to the bile passage failure. Hepatobiliary scanning in the diagnosis of neonatal cholestasis was characterised by high sensitivity (100%) but lower specificity (75%). In difficult cases the final diagnosis should be made on a basis of complex clinical, biochemical and radiological techniques and, if necessary, it should be verified by intraoperative cholangiography.

Biliary Atresia↗

Scintiscanning in diagnostics of hepatopulmonary syndrome in children.

BACKGROUND: Arterial blood oxygenation disturbances accompanying liver cirrhosis are referred to as hepatopulmonary syndrome (HPS). HPS develops due to the formation of intrapulmonary arteriovenous shunts and dilatation of the vascular bed. The aim of the study was to assess the incidence of arteriovenous shunts in children with hepatic cirrhosis and HPS suspected on the basis of clinical signs, qualified for liver transplantation. MATERIAL AND METHODS: The study was carried out in a group of 21 children aged from 1.2 to 17.7 years (mean age 8.4); 8 girls and 13 boys. The patients were diagnosed as follows: biliary cirrhosis due to extrahepatic bile duct impatency--12, post-inflammatory liver cirrhosis due to infection with HVB--2, autoimmune hepatitis--2, fibrosis of the liver--2, alpha 1-antitrypsin deficiency--1, progressive familial intrahepatic cholestasis--1, cystic fibrosis--1. The presence of arteriovenous anastomoses in the lungs was detected by scintiscanning utilizing microspheres (albumin macroaggregates). Under physiologic conditions, technetium-labeled microspheres injected i.v. are accumulated in pulmonary capillaries. Radioactivity detected in other organs (kidneys, brain) indicates the presence of pathologic shunts omitting the alveoli. A percentage ratio of radioactivity detected in the brain to that present in the lungs serves as the index of blood flow through the anastomosis (SI--shunt index). According to Grimon, the mean SI value for healthy children amounts to 0.43%, the values ranging from 1% to 2% are regarded as borderline ones, and those above 2% allow unequivocal diagnosis of HPS. RESULTS: The SI values obtained in the study ranged from 0.06 to 51%. In 7 patients SI exceeded 1%, reaching 1.23% in one, and over 3% in the remaining 6 patients. No correlations were found either between SI value and the etiology of cirrhosis, or between the index and clinical condition of the patient assessed according to Child-Pugh scale. CONCLUSIONS: 1. Scintiscanning revealed the presence of arteriovenous shunts in the lungs of 6/21 (28.6%) investigated patients. 2. No correlation was found between the severity of HPS and the etiology and stage of the underlying disease.

Adolescent↗

[The role of environmental factors in the formation of kidney calculi].

Various endo- and exogenous factors play a role in the urinary stones formation tract. The aim of the study was to define the type and frequency of hyperexcretion of lithogenic substances in school children population and to determine an influence of risk factors on hyperexcretion of crystallizing substances. The study included 220 school children. Preurolithiasis state (PS) was found in 30% children. The most frequently hyperoxaluria, hyperuricosuria and hypercalciuria were diagnosed and it may be connected with abnormal nutritional habits, excessive application of multivitamins, vitamin D and calcium, disturbances in drinking water chemical composition (higher amount of calcium, smaller amount of magnesium, abnormal pH). Urinary tract infections, particularly in children with obstructive uropathy are an important risk factor in the examined population. Positive familial history of urolithiasis in 43.3% children may indicate for the important role of the genetic factor in the pathogenesis of the disease.

Adolescent↗

[Etiology of nephrolithiasis in children: own observation].

Recurrent formation of renal calculi may be prevented by selective medical therapy designed to correct underlying metabolic disturbances in urine biochemistry. The aim of the study was to estimate potential risk factors of urolithiasis in 102 children before ESWL treatment. Metabolic disturbances followed by anatomical malformations of urinary tract, recurrent urinary tract infections caused by urease-induced microorganisms are the most frequent risk factors. In single cases possible risk factors were: immobilization and chronic corticosteroid therapy.

Child↗

[Hypocitraturia in children with urolithiasis].

Inhibitors of crystallization process play an important role in renal-stone forming patients. One of well-known inhibitor is citrate. The aim of the study was to define the type of metabolic abnormality in children with nephrolithiasis and the role of urinary citrate excretion. 52 children with nephrolithiasis were examined. Hypocitraturia was observed in 42.3% of patients, most frequently in children with hypercalciuria, hyperoxaluria, and hyperoxaluria with hyperuricosuria. Low urinary citrate excretion found in patients with nephrolithiasis may play an important role in the pathogenesis of the disease. Urinary citrate excretion should be examined in patients with nephrolithiasis.

Adolescent↗

[A form of premorbid condition of urolithiasis and urinary stone composition in children with urolithiasis].

In diagnosis, monitoring and prophylaxis of urolithiasis it is important to use simple, non-invasive tests. The aim of the study was to define the value of crystallizing ratios in urine in correlation with chemical stone composition in presumptive diagnosis and monitoring patients with urolithiasis. The study involved 102 children. An analysis of chemical stone composition was carried out in 62 cases. A correlation between values of crystallizing ratios in the urine, indicating the kind of preurolithiasis state and chemical stone composition has been found.

Adolescent↗

[Results of ESWL treatment in children with urolithiasis: own experience].

Actually extracorporeal shock wave lithotripsy (ESWL) is the most frequent method in the treatment of urolithiasis in children. The aim of the study was to estimate the results of ESWL in children with urolithiasis. Between 1991 and 1999 y, in our Department 260 "reno-ureteral units" in 203 children were treated by lithotripsy. Totally of 518 ESWL procedures were performed. In general efficacy of ESWL was 88.08%, in children with single stone in kidney--97.80%., with multiple stones in kidneys--78.65%, in ureterolithiasis--71.88%. For complete recovery in patients mean 1.99 ESWL procedures were performed on 1 "reno-ureteral unit" on the average diameter of the stone/stones 13.3 mm.

Adolescent↗

[Results of the treatment of pre-urolithiasis state in children with recurrent urinary tract infections].

Urolithiasis often coexists with recurrent urinary tract infections (RUTI). The aim of the study was to determine the correlation of preurolithiasis state (PS) and recurrent urinary tract infections and to establish an effect of the treatment UTI recurrence incidence. PS was found in 202(21.1%) children, most frequently: hyperoxaluria--in 61/202 (30.2%), hypercalciuria--in 32/202 (15.8%), and hyperuricosuria--in 30/202 (14.9%) children. Complex metabolic abnormality was observed in 62/202 (30.7%) patients. Therapeutic management comprised of: antibacterial prophylaxis, high fluid intake, proper diet, correction of urine pH, and pharmacological treatment if necessary. Disappearance of RUTI and PS in 88/202 (43.6%) children, disappearance of RUTI in spite of persistent PS in 36/202 (17.8%), and decrease of RUTI in 54/202 (26.7%) patients were method. In 110/202 (54.5) children PS disappeared.

Adolescent↗

[Beta-2 microglobulinuria in children with vesico-ureteral reflux and recurrent urinary tract infections].

Recurrent urinary tract infections in children with vesico-ureteral reflux are the one of risk factors in the process of reflux nephropathy. One of markers of early kidney parenchyma damage is beta 2-microglobulin. The aim of the study was to evaluate the value of beta 2-microglobulin excretion in urine and its serum levels in children with vesico-ureteral reflux and recurrent urinary tract infections. It was found that abnormal urinary excretion of beta 2-microglobulin and its serum levels of proceeded post-inflammatory changes in kidney parenchyma observed in imaging examinations of urinary tract and impared parameters of renal function in biochemical analyses.

Adolescent↗

Thermal helix-coil transition in UV irradiated collagen from rat tail tendon.

The thermal helix-coil transition in UV irradiated collagen solution, collagen film and pieces of rat tail tendon (RTT) were compared. Their thermal stability's were determined by differential scanning calorimeter (DSC) and by viscometric measurements. The denaturation temperatures of collagen solution, film and pieces of RTT were different. The helix-coil transition occur near 40 degrees C in collagen solution, near 112 degrees C in collagen film, and near 101 degrees C in pieces of RTT. After UV irradiation the thermal helix-coil transition of collagen samples were changed. These changes depend on the degree of hydratation.

Animals↗

Age-related muscle stiffness: predominance of non-reflex factors.

This study was aimed at assessing the contribution of reflex and non-reflex factors to the muscle tone of old female Wistar rats. The hind foot of a rat was flexed or extended at the ankle joint by 25 degrees over 250 ms. The resistance of the foot to passive movements (torque, mechanomyogram), as well as the reflex electromyographic activity in the gastrocnemius and tibialis anterior muscles, were recorded simultaneously. Moreover, the impact of the blockade of the reflex activity caused by the local anesthetic lignocaine (1-2 ml of a 2% solution, injected in the vicinity of the sciatic nerve) on the muscle tone was investigated. Additionally, old rats' hind leg muscle samples were analysed using fluorescent microscopy for the expression of fibronectin, which is an early marker of connective tissue formation. It has been shown that old rats are characterized by (i) a substantially increased resistance of flexor muscle stiffness (measured during extension) and unchanged resistance of extensors (measured during flexion), (ii) the loss of a major part of the reflex electromyographic activity and (iii) the increased content of fibronectin in muscles. Moreover, it has been shown that lignocaine, which completely blocked the electromyographic reflex activity in the gastrocnemius and tibialis anterior muscles in young animals, was unable to counteract the resistance of these muscles to passive movements in old rats. The present results suggest that the muscle stiffness seen in old rats is not due to a reflex response, but depends mainly on non-reflex factors--chiefly on a large overgrowth of non-elastic connective tissue replacing degenerated active muscle fibers.

Aging↗