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Biomedical subjects

Maria Nowakowska

Publications and source records attributed to Maria Nowakowska.

13 recordsLinked to original sources
PubMed2006

Pegylated tetraarylporphyrin entrapped in liposomal membranes. A possible novel drug-carrier system for photodynamic therapy.

A system of poly(ethylene glycol) bound tetraarylporphyrin entrapped in liposomal membranes was investigated. The interactions between the 5-(4-hydroxymethylphenyl)-10,15,20-tritolylporphyrin (Po) covalently attached to the poly(ethylene glycol) chain (PEG-Po), and phosphatidylcholine liposomes in the aqueous solution were studied. The adsorption of the investigated polymer to lipid vesicles was confirmed by measurements of dynamic light scattering and zeta potential. Experimental results demonstrate that the diameter of liposomes increased and the absolute value of the zeta potential decreased after addition of PEG-Po. The binding constants (K(b)) of Po chromophores to liposome in pH range from 5.2 to 9.0 were determined using fluorescence spectroscopy. The degree of binding was found to be pH-independent and the average value was 24.6 +/- 0.9 mg ml(-1). The acid-base properties of the porphyrin chromophores and their aggregation in an aqueous solution were also studied. pK values associated with imine-N protonation of the porphyrin core were found to be 2.59 and 0.68 at the ionic strength of 0.1 M. The equilibrium constant for dimerization, K(D), was found to be 5 x 10(3) M(-1).

Adsorption↗
PubMed2005

Interactions of porphyrin covalently attached to poly(methacrylic acid) with liposomal membranes.

The interactions between the 5-(4-acryloyloxyphenyl)-10,15,20-tritolylporphyrin covalently attached to poly(methacrylic acid) chain (PMA-Po) and phosphatidylcholine liposomes in aqueous solution at different pH values were studied. The binding constants (K(b)) for the liposome- PMA-Po in solutions in the pH range from 6.5 to 9.2 were determined using fluorescence spectroscopy. The binding was found to be efficient. The acid-base properties of the porphyrin chromophores were also studied. Both pK values associated with imine-N protonation of the porphyrin core were found to be 6.4. The quantum yield (Phi(Delta)) of singlet oxygen production by Po in the lipid-PMA-Po system was found to be high (0.88 +/- 0.05).

Acrylates↗
PubMed2004

Streptococcus group B (GBS)--characteristic, occurrence in children and adolescents with type 1 diabetes mellitus.

Group B streptococcus causes infections in woman during pregnancy and confinement, perinatal infections in newborns related to mothers carrier-state and in adults, mostly in the elderly, with one or more predisposing to infections conditions. Diabetes mellitus is the most common underlying condition. The aim of the study was to determine the frequency of GBS occurrence and GBS antibiotic susceptibility in children and adolescents with type 1 diabetes mellitus. In years 2000--2002 occurrence of GBS in some clinical materials (urine, swabs from pharynx and urogenital tract) taken from 161 diabetics: 90 girls and 71 boys, hospitalized for newly diagnosed diabetes or insufficient metabolic control/longer duration of diabetes and 37 children with hypostatura (control group) aged from 5-17 years, was examined. Susceptibility of isolated GBS strains to ampicillin, erythromycin and clindamycin was determined. GBS were obtained from different materials from 36 (22.4%) diabetic children--25 girls (27.8%), and 11 boys (15.5%). In all examined groups GBS was detected significantly in children with insufficient metabolic control/longer duration of diabetes (27 of 36 children; p =0.029, chi2=4.773). GBS in girls was isolated mainly from vestibule of vagina (25 cases) and in few cases (4) from the pharynx. GBS in boys was grown from materials from urethra (6 cases) and pharynx (5 cases). In the control group, GBS colonization was observed only in one case. All isolates (40 strains) were susceptible to penicillins, however lower susceptibility to erythromycin (3 resistant and 1 moderately sensitive) and clindamycin (3 resistant) were observed. High percentage of carriers of GBS both in girls and boys with diabetes mellitus is the potential risk factor of infection caused by GBS.

Adolescent↗
PubMed2004

[Antibiotic susceptibility analysis of Enterococcus spp. isolated from urine].

Recently increase of enterococcal infections has been observed. These bacteria, mainly Enterococcus faecalis and Enterococcus faecium are members of the normal flora of gastrointestinal tract but also are typical opportunistic pathogens. Enterococci are characterized by natural resistance to numerous antibiotics (among them cephalosporins), and also by easy acquired resistance to antibiotics. Infections caused by multiresistant strains are difficult in treatment, chronic, recurrent and sometimes fatal are described. Enterococcal infections are caused often by E. faecalis, rarely by E. faecium. In the last years other species of enterococci have been isolated from different clinical materials (E. casseliflavus, E. avium, E. durans, E. gallinarum). The aim of this study was to analyze the antibiotics susceptibility of Enterococcus spp. isolated from urine of children with urinary tract infection (UTI), hospitalized in the Upper Silesian Health Center of Child and Mother or treated ambulatory. Susceptibility of the 130 strains of E. faecalis and 41 E. faecium to: penicillin, tetracycline, high level of aminoglycoside (gentamycin 120 microg and streptomycin 300 microg), glycopeptides (vancomycin and teicoplanin), ciprofloxacin and nitrofurantoin was estimated. All isolated strains of E. faecalis (100%) were sensitive to glycopeptides (vancomycin and teicoplanin) and to nitrofurantoin, 96% strains were sensitive to penicillin, 43% to ciprofloxacin and 28% to tetracycline. All strains of E. faecium were sensitive to glycopeptides (vancomycin and teicoplanin), 32% strains were sensitive to penicillin, 19% to tetracycline 14% to ciprofloxacin and 50% to nitrofurantoin. Twenty two strains of E. faecalis (17%) and twelve strains of E. faecium (29%) were demonstrated high level resistance to aminoglycosides (HLAR). Among HLAR strains of enterococci, were observed strains of high level resistance only to streptomycin, high level resistance only to gentamycin and high level resistance to both aminoglycosides. The HLAR strains of E. faecalis and E. faecium were also resistant to other antibiotics: penicillin, tetracycline and ciprofloxacin. The most frequent cause of child urinary tract infection was E. faecalis, with high sensitivity to penicillins, glycopeptides and nitrofurantoin. The increased role of E. faecium and other strains of enterococci also has been shown. These species demonstrated sensitivity to glycopeptides, but resistance to other antibiotics, routinely used for treatment of UTI as well as to nitrofurantoin.

Anti-Bacterial Agents↗
PubMed2004

[Urinary tract infections in children--etiologic agents and susceptibility to antibiotics].

Urinary tract infections (UTIs) are common clinical problem in pediatric hospitals. The aim of this study was to compare the incidence of UTIs during two different time periods (from February 1999 to March 2000, and from April 2000 to September 2001) in pediatric patients treated in ambulatory or hospitalized in new children hospital. The frequency of occurrence of ESBL--producing Gram-negative rods increased during second period study. The isolated ESBL--producing strains were resistant also to aminoglicosides and trimethoprim/sulfamethoxazol Gram-negative rods were predominant microorganisms. Isolated organisms from urine samples included Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis, Proteus penneri, Proteus vulgaris, Morganella morganii, Citrobacter freundi, Serratia spp., Enterobacter cloacae, Pseudomonas aeruginosa, Staphylococcus aureus, CNS, Enterococcus spp. Streptococcus spp, and Candida spp. Enterococcus spp. were isolated from urine samples in 20% of cases. Only 9.4% of isolated Enterococcus spp. were high-level aminoglicoside resistant (HLAR) strains. No vancomycin-resistant Enterococcus spp. were isolated. Among coagulase-negative Staphylococci (CNS) methicillin resistant strains (MRCNS) were isolated in 43.3%.

Anti-Bacterial Agents↗
PubMed2004

[Intestinal colonization of newborns treated in intensive care units by multiple drug resistant microorganisms].

The aim of the study was to examine the digestive tract colonisation of the newborns by multiple drug resistant bacteria during hospitalization. On the day of admission, after 5 days of hospitalization and at the day of discharge swabs from the anus of the 31 newborns hospitalized in OITiPN were taken and cultured on nutrient and selective media for staphylococci, enterococci, gram negative bacilli and fungi. Susceptibility to antibiotics of bacteria was determined, with giving attention to such resistance mechanisms as: methicillin resistant staphylococci (MRS), high level aminoglycoside resistant (HLAR) and vancomycin resistant enterococci (VRE) and the production of extended spectrum beta-lactamases (type ESBL) by gram negative bacilli. On the day of admission in 7 newborns methicillin resistant staphylococci (MRSCN) were grown in 24 no multiple drug resistant bacteria were found. Among those in 23 already after 5 days of hospitalization, colonization by multiple drug resistant strains was determined: coagulase-negative methicillin resistant staphylococci (MRSCN) were found in 16 children, strains of enterococci (HLAR) in 3 newborns and gram negative ESBL (+) bacilli also in 3 cases. On the day of discharge from hospital (after 13-141 days) in 23 out of 24 newborns enteric tract colonization by multiple drug resistant strains was assessed. In the enteric tract of 3 newborns hospitalized up to 2 weeks coagulase-negative methicillin resistant staphylococci (MRSCN) and/or HLAR enterococci were found; gram negative bacilli that produce ESBL appeared in newborns hospitalized for longer than 14 days. They were isolated in 12 out of 21 newborns. Forming of the enteric tract bacterial flora of the long hospitalized newborns depends on the time of hospitalization as well as on the used therapy.

Drug Resistance, Multiple, Bacterial↗
PubMed2004

[Comparison of diagnostic methods for Helicobacter pylori detection and identification of cagA gene in clinical specimens].

Helicobacter pylori (H. pylori) is the principal cause of peptic ulcer disease and important risk factor in gastric cancer. Gastric mucosal biopsy specimens taken from 110 patients were examined by polymerase chain reaction (PCR), culture and urease test. The ureA gene was detected in 52 out of 110 examined samples. The cagA gene was detected in 35 (67.3%) out of these 52 specimens (ureA+). This gene was presented in all of patients with stomach ulcer, in 75.0% of patients with duodenitis, 69.6% of patients with duodenal ulcer and 58.3% of patients with gastritis. H. pylori was detected by culture in 24 (25.3%) out of 95 samples. These results were confirmed by PCR. H. pylori was detected additionally in 20 samples only by PCR. This bacterium was detected more frequently by PCR than by culture (46.3% vs 25.3%). Results obtained by using three methods: culture, urease test and PCR were concordant in 47.0% (39 out of 83 patients). In 16 (19.3%) cases H. pylori was detected by two methods: urease test and PCR. Infection was detected only by PCR in 3 (3.6%) cases and in 25 cases (30.1%) only by urease test.

Adult↗
PubMed2003

Interactions of temperature-responsive anionic polyelectrolytes with a cationic surfactant.

The interactions of temperature-responsive copolymers of sodium 2-acrylamido-2-methyl-1-propanesulfonate (AMPS) and N-isopropylacrylamide (NIPAM) with a cationic surfactant, dodecyltrimethylammonium chloride (DTAC), have been studied. The content of AMPS in the copolymers ranged from 1.1 to 9.6 mol%. The surface activity was higher for the polymers with lower AMPS content. It was found that DTAC undergoes association with the polymer chain, forming mixed polymer-surfactant micelles. The values of cac for the polymers were found in fluorescence studies using pyrene as the fluorescent probe. They were in the range 0.9-3.6x10(-3) M and were lower for polymers with higher AMPS content. An increase in DTAC concentration up to about its cmc results in a decrease of the LCST (lower critical solution temperature) of the copolymers, while further increase above the cmc results in an increase of the LCST. The minimum value of LCST in the presence of the surfactant is lower than the LCST of NIPAM homopolymer.

Journal Article↗
PubMed2003

"Smart" polymeric nanospheres as new materials for possible biomedical applications.

Novel random terpolymers of N-isopropylacrylamide (NIPAM), sodium 2-acrylamido-2-methyl-1-propanesulfonate (AMPS), and cinnamoyloxyethylmethacrylate (CEMA) were synthesized by free radical copolymerization using AIBN as an initiator. Five terpolymers were obtained by copolymerization of the monomer mixtures containing a fixed amount of 10 mol % of AMPS while the content of CEMA ranged from 5 to 25 mol % and was changed in 5 mol % increments. The terpolymers obtained are water-soluble. Because of their amphiphilic nature they undergo self-organization in the aqueous solution with the formation of micelles capable of solubilizing sparingly water soluble organic compounds, such as drugs. The terpolymers are susceptible to three external stimuli, i.e. temperature, ionic strength and UV light. Due to the presence of NIPAM in the terpolymers they display the lower critical solution temperature (LCST), the presence of AMPS makes them sensitive to the ionic strength of the solution, while the light-responsiveness of the terpolymers is due to the presence of cinnamoyl chromophores, which undergo photodimerization when irradiated with UV light at about 280 nm. Application of any of these stimuli alone or in combination with other stimuli allows changing the copolymer properties in a controlled way.

Journal Article↗
PubMed2002

[Bacterial and fungal flora in some clinical materials in children with diabetes type 1].

BACKGROUND: Children with poorly controlled diabetes are exposed to infections often caused by endogenous flora. AIM: To estimate incidence of pathogenic and opportunistic bacteria and fungi of Candida species. MATERIAL AND METHODS: The urine, smears from the oral cavity and the pharynx as well as from the urogenital tract were examined in 130 children (62 boys and 68 girls) hospitalised because of newly diagnosed (53 children) or poorly controlled diabetes (77 patients). 29 children with short stature were the control group, in these children only the urine and smears from the oral cavity and the pharynx were only examined. Culture and identification of microorganisms were performed according to the methods used in microbiological diagnosis. Antifungal susceptibility testing was estimated with FUNGITEST Sanofi Pasteur and ATB Fungus bioMérieux. RESULTS: Staphylococcus aureus in 43 diabetic children (33%) was observed. Staphylococcus aureus from different clinical materials was isolated; there was no difference in the frequency of occurrence of S. aureus in flora of the oral cavity and the pharynx in diabetic children in comparison with healthy children. Streptococcus group B in 29 (22.3%) was isolated, among them in 10 children from the pharynx. In healthy children Streptococcus group B was not observed. A significant bacteriuria was observed in 15 diabetic children (11.5%) and in 2 healthy children (6.9%). Fungi in 58 diabetic children (44.6%) were observed. Most often isolated species was Candida albicans (49 children), rarely other species. Candida spp. from different clinical materials was isolated, also in a non significant amount from the urine. CONCLUSIONS: Microbial analysis of vagina should be routinely performed in diabetic adolescents. Urine of diabetics should be examined towards fungi.

English Abstract↗
PubMedDate not supplied

Novel water-soluble photosensitizers from dextrans.

Novel water-soluble polymeric photosensitizers based on the natural polymer dextran were synthesized and studied. The modified dextran contained photoactive anthracene (An) chromophores. They were soluble in water with the solubility decreasing with an increase in the number of An moieties bound to the polymeric chain. In aqueous solutions, the macromolecules adopted a compact conformation which resulted in the formation of hydrophobic microdomains. The properties of these domains were characterized with molecular probes such as perylene and pyrazolo-quinoline derivative. The polymer absorbed in the UV/vis region and photosensitized reactions mediated by energy and/or electron transfer from electronically excited An to the molecules of organic compounds solubilized in polymeric microdomains or resided in water.

Carbohydrate Sequence↗
PubMedDate not supplied

Novel water-soluble photosensitizer based on starch and containing porphyrin.

Novel water-soluble polymeric photosensitizers (SPO) based on starch and containing porphyrin chromophores were synthesized and studied. The polymers were soluble in water and in dimethyl sulfoxide. Photophysical studies and solubilization of molecular probes proved the formation of hydrophobic, rigid microdomains in an aqueous solution of SPO; they were created due to the clustering of porphyrin chromophores attached to the polymer chain. SPO polymers absorbed light from the UV-visible spectral region. The polymers could sensitize photochemical reactions mediated by electron transfer, energy transfer or both, from the singlet-excited state of porphyrin chromophores to the molecules of organic compounds solubilized in the hydrophobic microdomains or residing in the water phase.

Molecular Structure↗