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Dive into the research topics where Jan K. Nowak is active.

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Featured researches published by Jan K. Nowak.


Scientific Reports | 2015

Prevalence and correlates of vitamin K deficiency in children with inflammatory bowel disease

Jan K. Nowak; Urszula Grzybowska-Chlebowczyk; Piotr Landowski; Anna Szaflarska-Popławska; Beata Klincewicz; Daria Adamczak; Tomasz Banasiewicz; Andrzej Plawski; Jarosław Walkowiak

Although vitamin K deficiency has been implicated in adult inflammatory bowel disease (IBD), its prevalence in pediatric IBD remains unknown. We carried out a cross-sectional study in 63 children with Crohns disease (CD) and 48 with ulcerative colitis (UC) to assess the prevalence of vitamin K deficiency and to search for potential correlation between vitamin K status and pediatric IBD activity. Vitamin K status was assessed using protein induced by vitamin K absence-II (PIVKA-II; ELISA). Prevalence of vitamin K deficiency was 54.0% in CD and 43.7% in UC. Vitamin K deficiency was more common in patients with higher CD activity, in CD patients with higher mass Z-scores, and less common among children with CD treated with infliximab. Relation of vitamin K deficiency to pediatric IBD clinical course and treatment demand further research.


Scientific Reports | 2015

Green tea extract decreases starch digestion and absorption from a test meal in humans: a randomized, placebo-controlled crossover study

Klaudia Lochocka; Joanna Bajerska; Aleksandra Glapa; Ewa Fidler-Witoń; Jan K. Nowak; Tomasz Szczapa; Philip Grebowiec; Aleksandra Lisowska; Jarosław Walkowiak

Green tea is known worldwide for its beneficial effects on human health. However, objective data evaluating this influence in humans is scarce. The aim of the study was to assess the impact of green tea extract (GTE) on starch digestion and absorption. The study comprised of 28 healthy volunteers, aged 19 to 28 years. In all subjects, a starch 13C breath test was performed twice. Subjects randomly ingested naturally 13C-abundant cornflakes during the GTE test (GTE 4 g) or placebo test. The cumulative percentage dose recovery (CPDR) was significantly lower for the GTE test than for the placebo test (median [interquartile range]: 11.4% [5.5–15.5] vs. 16.1% [12.7–19.5]; p = 0.003). Likewise, CPDR expressed per hour was considerably lower in each point of the measurement. In conclusion, a single dose of green tea extract taken with a test meal decreases starch digestion and absorption.


Biomedical Optics Express | 2014

Quantitative assessment of oral mucosa and labial minor salivary glands in patients with Sjögren’s syndrome using swept source OCT

Ireneusz Grulkowski; Jan K. Nowak; Karol Karnowski; Paweł Zebryk; Mariusz Puszczewicz; Jarosław Walkowiak; Maciej Wojtkowski

Three-dimensional imaging of the mucosa of the lower lip and labial minor salivary glands is demonstrated in vivo using swept source optical coherence tomography (OCT) system at 1310 nm with modified interface. Volumetric data sets of the inner surface of the lower lip covering ~230 mm(2) field are obtained from patients with Sjögrens syndrome and a control group. OCT enables high-resolution visualization of mucosal architecture using cross-sectional images as well as en-face projection images. Comprehensive morphometry of the labial minor salivary glands is performed, and statistical significance is assessed. Statistically significant differences in morphometric parameters are found when subgroups of patients with Sjögrens syndrome are analyzed.


Scientific Reports | 2015

Comparison of fecal pyruvate kinase isoform M2 and calprotectin in acute diarrhea in hospitalized children

Elzbieta Czub; Jan K. Nowak; Jerzy Moczko; Aleksandra Lisowska; Aleksandra Banaszkiewicz; Tomasz Banasiewicz; Jarosław Walkowiak

Fecal concentrations of pyruvate kinase isoform M2 (M2-PK) and calprotectin (FC) serve as biomarkers of inflammation of gastrointestinal mucosa. The value of M2-PK in discriminating between patients with viral and bacterial acute diarrhea (AD) is currently unknown. We analyzed M2-PK and FC concentrations in fifty hospitalized children with AD (29 of which were caused by rotavirus and 21 by Salmonella enteritidis) as well as 32 healthy subjects. There was no difference in the areas under the receiver operating characteristic curves plotted for the two tests in differentiating rotaviral from bacterial AD. The sensitivity and specificity of M2-PK at optimal cut-off (20 U/g) were 75.9% and 71.4%, respectively. M2-PK and FC had similar values in distinguishing between children with AD caused by rotavirus and Salmonella enteritidis. The performance of both tests in hospitalized patients did not meet the needs of everyday clinical practice. Moreover, no advantage of fecal tests over the measurement of CRP was documented.


Advances in Medical Sciences | 2017

Mulberry leaf extract decreases digestion and absorption of starch in healthy subjects—A randomized, placebo-controlled, crossover study

Jan Józefczuk; Klaudia Malikowska; Aleksandra Glapa; Barbara Stawińska-Witoszyńska; Jan K. Nowak; Joanna Bajerska; Aleksandra Lisowska; Jarosław Walkowiak

PURPOSE Mulberry (Morus alba L.) leaf tea has recently received much attention as a dietary supplement due to the wide range of putative health benefits, such as antidiabetic effects. Nevertheless, data evaluating its influence on carbohydrate metabolism in humans are scarce. The present study aims to investigate the effect of mulberry leaf extract supplementation on starch digestion and absorption in humans. MATERIALS AND METHODS The study comprised of 25 healthy subjects, aged 19-27 years. In all subjects, a starch 13C breath test was performed twice in a crossover and single blind design. Subjects were initially randomized to ingest naturally 13C-abundant cornflakes (50g cornflakes+100ml low fat milk) either with the mulberry leaf extract (36mg of active component-1-deoxynojirimycin) or the placebo and each subject received the opposite preparation one week later. RESULTS The cumulative percentage dose recovery was lower for the mulberry leaf extract test than for the placebo test (median [quartile distribution]: 13.9% [9.9-17.4] vs. 17.2% [13.3-20.6]; p=0.015). A significant decrease was detectable from minute 120 after the ingestion. CONCLUSIONS A single dose of mulberry leaf extract taken with a test meal decreases starch digestion and absorption. These findings could possibly be translated into everyday practice for improvement of postprandial glycemic control.


Journal of Cystic Fibrosis | 2016

Pancreatic Elastase-1 Quick Test for rapid assessment of pancreatic status in cystic fibrosis patients

Jarosław Walkowiak; Aleksandra Glapa; Jan K. Nowak; L. Bober; Nataliya Rohovyk; Ewa Wenska-Chyży; Paulina Sobkowiak; Aleksandra Lisowska

BACKGROUND At present, fecal elastase-1 ELISA determination is the most sensitive and specific tubeless pancreatic function test available. However, the results are not available the same day in routine clinical practice. This prospective study aims at evaluating the sensitivity and specificity of the Elastase-1 Quick™ Test by comparing the results with the ELISA test. METHODS The study was composed of three groups: the screening-diagnosed cystic fibrosis (CF) patients (n=28), the screened, but non-CF subjects (n=36) and non-screened CF patients (n=62). Pancreatic status (normal vs abnormal) was evaluated using the Pancreas Elastase-1 Quick™ Test. Fecal elastase-1 concentration was determined with a commercially available ELISA kit, used as reference. The cut-off for abnormal results was set at <200μg/g of stool. RESULTS The Pancreatic Elastase-1 Quick Test™ showed the following sensitivities and specificities in the studied groups: 92.8% and 96.6% in all subjects, 90.5% and 100% in screening samples, and 92.8 and 90.5% in CF patients. CONCLUSION Pancreatic Elastase-1 Quick Test™ proves to be a rapid and reliable option to qualitatively evaluate pancreatic function for diagnostic purposes in a clinical setting of CF care.


International Journal of Molecular Sciences | 2017

Determinants of Serum Glycerophospholipid Fatty Acids in Cystic Fibrosis

Sławomira Drzymała-Czyż; Patrycja Krzyżanowska; Berthold Koletzko; Jan K. Nowak; Anna Miśkiewicz-Chotnicka; Jerzy Moczko; Aleksandra Lisowska; Jarosław Walkowiak

The etiology of altered blood fatty acid (FA) composition in cystic fibrosis (CF) is understood only partially. We aimed to investigate the determinants of serum glycerophospholipids’ FAs in CF with regard to the highest number of FAs and in the largest cohort to date. The study comprised 172 CF patients and 30 healthy subjects (HS). We assessed Fas’ profile (gas chromatography/mass spectrometry), CF transmembrane conductance regulator (CFTR) genotype, spirometry, fecal elastase-1, body height and weight Z-scores, liver disease, diabetes and colonization by Pseudomonas aeruginosa. The amounts of saturated FAs (C14:0, C16:0) and monounsaturated FAs (C16:1n-7, C18:1n-9, C20:1n-9, C20:3n-9) were significantly higher in CF patients than in HS. C18:3n-6, C20:3n-6 and C22:4n-6 levels were also higher in CF, but C18:2n-6, C20:2n-6 and C20:4n-6, as well as C22:6n-3, were lower. In a multiple regression analysis, levels of seven FAs were predicted by various sets of factors that included age, genotype, forced expiratory volume in one second, pancreatic status and diabetes. FA composition abnormalities are highly prevalent in CF patients. They seem to be caused by both metabolic disturbances and independent clinical risk factors. Further research into the influence of CFTR mutations on fat metabolism and desaturases’ activity is warranted.


Pancreas | 2016

Smaller Width of the Pancreatic Duct During Secretin-Enhanced Magnetic Resonance Cholangiopancreatography in Pancreatic-Sufficient Cystic Fibrosis Patients.

Katarzyna Jończyk-Potoczna; Jan K. Nowak; Edyta Madry; Katarzyna Katulska; Sylwia Stężowska-Kubiak; Jerzy Moczko; Aleksandra Lisowska; Jarosław Walkowiak

Objectives New tools are needed in cystic fibrosis (CF) diagnostics in pancreatic-sufficient CF (PS-CF) patients. Secretin-enhanced magnetic resonance cholangiopancreatography (SE-MRCP) allows for improved assessment of the width of the pancreatic duct. Methods Sixteen PS-CF patients and 17 healthy volunteers underwent SE-MRCP. The width of the pancreatic duct in the head, the body, and the tail of the pancreas was measured at the baseline and 1, 2, 3, 5, and 10 minutes after secretin administration. Results The width of the pancreatic duct in the head of the pancreas did not differ between the groups at the baseline; after 10 minutes of secretin stimulation, it was smaller in PS-CF patients (median, 1.4 mm [first-third quartile, 1.3–2.0] vs 2.2 mm [1.7–2.4], P = 0.008). The area under the curve for discrimination between the 2 groups using this parameter was 0.77 (95% confidence interval, 0.60–0.93). Conclusions The SE-MRCP identified differences in the width of the pancreatic duct between PS-CF and healthy volunteers. Further improvements of the method are needed to augment its clinical utility.


Acta Biochimica Polonica | 2016

Conflicting results of non-invasive methods for detection of Helicobacter pylori infection in children with celiac disease - a preliminary study.

Jan Józefczuk; Edyta Mądry; Jan K. Nowak; Marek Walkowiak; Klaudia Łochocka; Tomasz Banasiewicz; Andrzej Plawski; Jarosław Kwiecień; Jarosław Walkowiak

BACKGROUND There are no data addressing the usefulness of non-invasive tests for the detection of Helicobacter pylori (HP) infection in celiac disease (CD). AIM The aim of this study was to compare two most sensitive and specific tests - urea breath test (UBT) and fecal antigen test (FAT) in HP diagnosis in CD patients. MATERIALS AND METHODS The study comprised of 76 CD patients, 49 healthy subjects (HS) and 35 patients who underwent differential diagnosis due to abdominal pain (AP patients). The presence of HP infection was evaluated using the (13)C isotope-labeled UBT and FAT (ELISA). RESULTS HP infection was diagnosed based on UBT and FAT in 8 (16.3%) and 7 (14.3%) HS, and in 8 (10.5%) CD patients and 12 (34.3%) AP patients, respectively, using both tests. The prevalence of conflicting results in comparison with positive results (obtained with any of the two tests) was distinctly higher (54.5%) in CD group than in other subjects (23.3%); however, due to low HP prevalence, it did not reach the level of significance (p<0.1759). CONCLUSION CD may increase the risk of divergent results of non-invasive tests used for the detection of HP infection in children. Since UBT is the most reliable test, we suggest its standard use as a method of choice in pediatric CD - at least until new evidence emerges supporting a different approach.


PLOS ONE | 2015

Optical coherence tomography identifies lower labial salivary gland surface density in cystic fibrosis.

Jan K. Nowak; Ireneusz Grulkowski; Karol Karnowski; Maciej Wojtkowski; Jarosław Walkowiak

The labial minor salivary glands (LSGs) are easily accessible mucus-secreting structures of the alimentary tract that may provide new information on the basis of gastrointestinal complications of cystic fibrosis (CF). It was shown that they are destructed in the course of cystic fibrosis. We employed wide-field, micrometer resolution in vivo optical coherence tomography to assess the surface density of LSGs in 18 patients with CF and 18 healthy subjects. The median LSGs’ surface densities in CF patients, and in the control group were 4.32 glands/cm2 and 6.58 glands/cm2, respectively (p = 0.006; Mann-Whitney U test). A lower LSG surface density is a previously unrecognized CF-related pathology of the alimentary tract.

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Jarosław Walkowiak

Poznan University of Medical Sciences

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Aleksandra Lisowska

Poznan University of Medical Sciences

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Aleksandra Glapa

Poznan University of Medical Sciences

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Edyta Mądry

Poznan University of Medical Sciences

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Jerzy Moczko

Poznan University of Medical Sciences

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Patrycja Krzyżanowska

Poznan University of Medical Sciences

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Tomasz Banasiewicz

Poznan University of Medical Sciences

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Ireneusz Grulkowski

Nicolaus Copernicus University in Toruń

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Maciej Wojtkowski

Nicolaus Copernicus University in Toruń

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Karol Karnowski

University of Western Australia

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