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Biomedical subjects

S Nowicki

Publications and source records attributed to S Nowicki.

At least 19 recordsLinked to original sources
PubMed2006

Renal allograft injury is associated with urinary tract infection caused by Escherichia coli bearing adherence factors.

Urinary tract infections are the most common infection in renal transplant patients and Escherichia coli (E. coli) is the most common clinical isolate. Although acute allograft injury (AAI) secondary to urinary tract infection (UTI) has been reported, the incidence of AAI associated with UTI, the virulence factors express by uropathic E. coli and whether virulence factors are associated with renal allograft outcome have not been described. We collected E. coli from our renal transplant patients with UTI, determined O:H serotypes, P and Dr fimbriae expression and the clinical presentation and allograft function during the UTI and post-UTI period. Pyelonephritis occurred in 40% of our patients, 82% of which had AAI (>20% increase in SCr). Sixty-two percent of E. coli isolates that expressed P fimbriae were associated with AAI, whereas only 29% that did not express P fimbriae had AAI (p = 0.03). The pattern of P fimbriae and O serotypes differed from reported isolates, as the P fimbriae PapG class II and the O25 serotype were the most common. Dr adhesin was expressed on 7 isolates, including 2 of 3 with urosepsis. We propose a unique pattern of uropathogenic serotypes and adherence factors contribute to acute allograft injury in renal transplant patients with UTI.

Adult↗
PubMed2005

Low sodium intake induces an increase in renal monoamine oxidase activity in the rat. Involvement of an angiotensin II dependent mechanism.

AIMS: The interplay between natriuretic dopamine and antinatriuretic angiotensin II represents an important mechanism for the regulation of renal sodium and water excretion. Monoamine oxidase is the main metabolizing pathway for dopamine in the renal cortex. In this study, we have analysed the effect of low sodium feeding and AT1 receptor blockade on renal dopamine metabolism by monoamine oxidase. METHODS: Four groups of rats were studied: 1, normal salt diet (NS); 2, low salt diet (LS); 3, NS receiving Losartan (Los, specific AT1 receptor antagonist, 20 mg kg(-1) bwt day(-1), NS + Los); 4, LS receiving Los (LS + Los). RESULTS: Urinary dopamine excretion was lower in LS than in NS rats (543 +/- 32 vs. 680 +/- 34 ng day(-1) 100 g(-1) bwt, P < 0.05). When treated with Los, DOPAC excretion and urinary DOPAC/dopamine ratio fell significantly in the LS + Los group as compared with the LS group (1199 +/- 328 vs. 3081 +/- 681 ng day(-1) 100 g(-1) bwt and 1.90 +/- 0.5 vs. 5.7 +/- 1.2, respectively, both P < 0.02). Losartan increased hydroelectrolyte excretion in the LS group. No changes were found in the NS + Los group. Aromatic L-amino acid decarboxylase activity in cortex was similar in NS and LS rats. Instead, monoamine oxidase activity was higher in cortical homogenates from LS rats (in nmol mg tissue(-1) h(-1): NS 7.66 +/- 0.52; LS 9.82 +/- 0.59, P < 0.05) and this difference was abolished in LS + Los rats (7.34 +/- 0.49 nmol mg tissue(-1) h(-1), P < 0.01, vs. LS). CONCLUSIONS: We have concluded that low levels of dopamine in the urine of LS rats are because of an increase in the activity of renal monoamine oxidase and that angiotensin II mediates this increase through stimulation of AT1 receptors.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2005

Dra/AfaE adhesin of uropathogenic Dr/Afa+ Escherichia coli mediates mortality in pregnant rats.

Escherichia coli bearing adhesins of the Dr/Afa family frequently causes urogenital infections during pregnancy in humans and has been associated with mortality in pregnant rats. Two components of the adhesin, Dra/AfaE and Dra/AfaD, considered virulence factors, are responsible for bacterial binding and internalization. We hypothesize that gestational mortality caused by Dr/Afa+ E. coli is mediated by one of these two proteins, Dra/AfaE or Dra/AfaD. In this study, using afaE and/or afaD mutants, we investigated the role of the afaE and afaD genes in the mortality of pregnant rats from intrauterine infection. Sprague-Dawley rats, on the 17th day of pregnancy, were infected with the E. coli afaE+ afaD and afaE afaD+ mutants. The clinical E. coli strain (afaE+ afaD+) and the afaE afaD double mutant were used as positive and negative controls, respectively. The mortality rate was evaluated 24 h after infection. The highest maternal mortality was observed in the group infected with the afaE+ afaD+ strain, followed by the group infected with the afaE+ afaD strain. The mortality was dose dependent. The afaE afaD double mutant did not cause maternal mortality, even with the highest infection dose. The in vivo studies corresponded with the invasion assay, where the afaE+ strains were the most invasive (afaE+ afaD strain > afaE+ afaD+ strain), while the afaE mutant strains (afaE afaD+ and afaE afaD strains) seemed to be noninvasive. This study shows for the first time that the afaE gene coding for the AfaE subunit of Dr/Afa adhesin is involved in the lethal outcome of gestational infection in rats. This lethal effect associated with AfaE correlates with the invasiveness of afaE+ E. coli strains in vitro.

Adhesins, Escherichia coli↗
PubMed2002

Brain development, song learning and mate choice in birds: a review and experimental test of the "nutritional stress hypothesis".

The nutritional stress hypothesis explains how learned features of song, such as complexity and local dialect structure, can serve as indicators of male quality of interest to females in mate choice. The link between song and quality comes about because the brain structures underlying song learning largely develop during the first few months post-hatching. During this same period, songbirds are likely to be subject to nutritional and other stresses. Only individuals faring well in the face of stress are able to invest the resources in brain development necessary to optimize song learning. Learned features of song thus become reliable indicators of male quality, with reliability maintained by the developmental costs of song. We review the background and assumptions of the nutritional stress hypothesis, and present new experimental data demonstrating an effect of nestling nutrition on nestling growth, brain development, and song learning, providing support for a key prediction of the hypothesis.

Age Factors↗
PubMed2001

Auditory representation of the vocal repertoire in a songbird with multiple song types.

Neural mechanisms for representing complex communication sounds must solve the problem of encoding multiple and potentially overlapping signals. Birdsong provides an excellent model for such processing, in that many songbird species produce multiple song types. Although auditory song representations in single song type species have been studied, how song is represented in the brains of species that sing multiple song types remains unknown. Here we examine song type representations in swamp sparrows (Melospiza georgiana), a multiple song type species, by making in vivo intracellular recordings from the telencephalic nucleus HVc, the major auditory-vocal interface in the songbird brain. These recordings show that single HVc relay neurons often generate action potentials to playback of only a single song type, even though synaptic inputs on these cells can be activated by playback of other song types in the bird's repertoire and songs of other birds. These subthreshold response patterns suggest that the song evoked action potential discharge of a single relay neuron is more selective than its presynaptic network. One component of this presynaptic network is likely to be in HVc, because multiple recordings from single birds show that different relay neurons can respond best to different song types, whereas single interneurons can generate action potentials to all song types in the bird's repertoire. These results show that single HVc neurons can generate song type-specific action potential responses, a feature that may facilitate the selective auditory encoding of multiple learned vocalizations in a single brain area.

Action Potentials↗
PubMed2001

Ampicillin-resistant Escherichia coli in gestational pyelonephritis: increased occurrence and association with the colonization factor Dr adhesin.

The pattern of ampicillin resistance and possible association with virulence factors of 78 Escherichia coli isolates taken from 78 pregnant women with pyelonephritis were evaluated. The current incidence of ampicillin resistance among pyelonephritis isolates (46%) was significantly higher than that reported in 1985 (22%). Resistance was found more frequently during the first (60%) and third (53%) trimesters than during the second trimester (33%). Of all dra(+) E. coli isolates, 75% were ampicillin resistant, whereas dra(+) isolates of O75 serotype E. coli accounted for 87% of ampicillin-resistant strains. The significant increase of ampicillin resistance among gestational pyelonephritis E. coli and the association with the dra gene cluster encoding colonization and invasive capacity may warrant further study involving obstetric and neonate wards, with the latter being at the higher risk for potential problems.

Adhesins, Escherichia coli↗
PubMed2001

Phosphorylation of the catalytic subunit of rat renal Na+, K+-ATPase by classical PKC isoforms.

In this study we have evaluated the specificity of different PKC isozymes for the phosphorylation of the catalytic alpha1 subunit of rat renal Na+,K+-ATPase (alpha1 Na+,K+-ATPase). Using in vitro phosphotransferase assays we found that classical PKCs (cPKCs) alpha, betaI, and gamma efficiently phosphorylate alpha1 Na+,K+-ATPase. However, alpha1 Na+,K+-ATPase was a poor substrate for the novel PKCs (nPKCs) delta and epsilon. Two-dimensional phosphopeptide mapping revealed a similar pattern of phosphorylation by all cPKCs. The functional significance of this finding was evaluated by measuring Na+,K+-ATPase activity (assessed by 86Rb+ uptake) in COS-7 cells expressing the rat alpha1 Na+,K+-ATPase. 1-oleoyl-2-acetoyl-sn-glycerol (OAG), a nonselective PKC activator, inhibited Na+,K+-ATPase activity in this system. On the other hand, 12-deoxyphorbol-13-phenylacetate (DPP), which preferentially activates nPKCepsilon, did not affect 86Rb+ uptake. These results indicate a differential pattern of phosphorylation and regulation of rat renal Na+,K+-ATPase activity by PKC isoforms and suggest an important role for cPKCs in the physiological regulation of the pump.

Animals↗
PubMed2001

African American children's ability to identify emotion in facial expressions and tones of voice of European Americans.

This study examined whether African American children's ability to identify emotion in the facial expressions and tones of voice of European American stimuli was comparable to their European American peers and related to personality, social competence, and achievement. The Diagnostic Analysis of Nonverbal Accuracy (DANVA ; Nowicki & Duke, 1994) was administered to 84 African American children. It was found that they performed less accurately on adult and child tones of voice and adult facial expressions. Further, girls' ability to read emotion in tones of voice was related to better social competence and achievement, whereas boys' ability to identify emotion in adult tones of voice was related to teacher-rated social competence. Results suggest that more research is needed with ethnic groups to clarify the impact of nonverbal processing skills on social and achievement outcomes.

Achievement↗
PubMed2001

Expression of decay accelerating factor in endometrial adenocarcinoma is inversely related to the stage of tumor.

PROBLEM: Decay accelerating factor (DAF) is implicated in protection of cell membrane from toxicity of complement. In this study, we investigated a hypothesis that DAF is up-regulated in the endometrial adenocarcinoma, which could increase potential of malignant cells to escape destruction by complement. METHODS: DAF density was evaluated in endometrial biopsies of patients with adenocarcinoma at various stages and compared with ten endometrial biopsies from non-malignant patients at the proliferative phase. RESULTS: DAF expression in normal proliferative endometrium varied between 1 and 30%. While DAF density in patients with stage I cancer was in the range 56-98% (mean 78%), stage III values varied from 28 to 16% (mean 21%), P < 0.05. DAF density in the well-differentiated Ishikawa cell line was two-fold higher than in metastatic cell line AN3CA. CONCLUSIONS: Our findings are consistent with a hypothesis that endometrial adenocarcinoma of early stage that is exposed to complement attack may up-regulate DAF to protect malignant cells from complement lysis.

Adenocarcinoma↗
PubMed2001

Rapid receptor-clustering assay to detect uropathogenic and diarrheal Escherichia coli isolates bearing adhesins of the Dr family.

Infections caused by Escherichia coli isolates expressing adhesins of the Dr family are associated with diarrhea and urinary tract infections, and these E. coli strains recognize the complement regulatory protein decay-accelerating factor (DAF) as their receptor. Clustering of the DAF receptor at the sites of bacterial adherence to epithelial cells is proposed as an alternative to PCR assay for rapid detection of Dr-positive E. coli.

Adhesins, Escherichia coli↗
PubMed2001

Physical fitness and self-reported physical exercise among college men and women in 1987 and 1997.

The study examined the relations of self-reported physical activity levels and physical fitness scores for two samples of college students assessed in 1987 (n = 261) and in 1997 (n = 243). Significantly greater exercise was reported by the 1997 women than the 1987 women; amount of exercise reported by men did not differ. For both samples, greater exercise was associated with increased fitness for women and men as assessed by the Hall 1986 Physical Fitness Test Profile, comprised of measures on body fat composition; grip strength; muscle endurance, flexibility, resting heart rate; systolic and diastolic blood pressures; and aerobic power. For the 1987 sample men were more fit than women. For the 1997 sample, women were more fit than men. The 1997 women were more fit than the 1987 women; there was no difference on overall fitness measures of the two samples of men.

Adult↗
PubMed2000

Nestling growth and song repertoire size in great reed warblers: evidence for song learning as an indicator mechanism in mate choice.

Females of many songbird species show a preference for mating with males that have larger song repertoires, but the advantages associated with this preference are uncertain. We tested the hypothesis that song complexity can serve as an indicator of male quality because the development of the brain regions underlying song learning and production occurs when young birds typically face nutritional and other stresses, so that song reflects how well a male fared during post-hatch development. A key prediction of this hypothesis is that variation in nestling condition should correspond to variation in the adult song repertoires of individuals. We used data from a long-term study of the great reed warbler (Acrocephalus arundinaceus) to test this prediction, correlating two measures of nestling development with subsequent repertoire size of males. We found that the length of the innermost primary feather, a standard measure of development, significantly predicted first-year repertoire size. The relationship between repertoire size and body mass was nearly significant, in spite of the large variance inherent in this measure. These data support the idea that song may provide females with information about a male's response to developmental stress, which in turn is expected to correlate with indirect or direct benefits she might receive.

Animals↗
PubMed2000

Role of decay-accelerating factor domains and anchorage in internalization of Dr-fimbriated Escherichia coli.

Dr-fimbriated Escherichia coli capable of invading epithelial cells recognizes human decay-accelerating factor (DAF) as its cellular receptor. The role of extracellular domains and the glycosylphosphatidylinositol anchor of DAF in the process of internalization of Dr(+) E. coli was characterized in a cell-cell interaction model. Binding of Dr(+) E. coli to the short consensus repeat 3 domain of DAF expressed by Chinese hamster ovary cells was critical for internalization to occur. Deletion of short consensus repeat 3 domain or replacement of Ser(165) by Leu in this domain, or the use of a monoclonal antibody to this region abolished internalization. Replacing the glycosylphosphatidylinositol anchor of DAF with the transmembrane anchor of membrane cofactor protein or HLA-B44 resulted in abolition or reduction of internalization respectively. Cells expressing glycosylphosphatidylinositol-anchored DAF but not the transmembrane-anchored DAF internalized Dr(+) E. coli through a glycolipid pathway, since the former cells were more sensitive to inhibition by methyl-beta-cyclodextrin, a sterol-chelating agent. Electron microscopic studies revealed that the intracellular vacuoles containing the internalized Dr(+) E. coli were morphologically distinct between the anchor variants of DAF. The cells expressing glycosylphosphatidylinositol-anchored DAF contained a single bacterium in tight-fitting vacuoles, while the cells expressing transmembrane-anchored DAF contained multiple (two or three) bacteria in spacious phagosomes. This finding suggests that distinct postendocytic events operate in the cells expressing anchor variants of DAF. We provide direct evidence for the DAF-mediated internalization of Dr(+) E. coli and demonstrate the significance of the glycosylphosphatidylinositol anchor, which determines the ability and efficiency of the internalization event.

Adhesins, Escherichia coli↗
PubMed2000

Dopamine-induced translocation of protein kinase C isoforms visualized in renal epithelial cells.

Short-term regulation of sodium metabolism is dependent on the modulation of the activity of sodium transporters by first and second messengers. In understanding diseases associated with sodium retention, it is necessary to identify the coupling between these messengers. We have examined whether dopamine, an important first messenger in tubular cells, activates and translocates various protein kinase C (PKC) isoforms. We used a proximal tubular-like cell line, LLCPK-1 cells, in which dopamine was found to inhibit Na(+)-K(+)-ATPase in a PKC-dependent manner. Translocation of PKC isoforms was studied with both subcellular fractionation and confocal microscopy. Both techniques revealed a dopamine-induced translocation from cytosol to plasma membrane of PKC-alpha and -epsilon, but not of PKC-delta, -gamma, and -zeta. The process of subcellular fractionation resulted in partial translocation of PKC-epsilon. This artifact was eliminated in confocal studies. Confocal imaging permitted detection of translocation within 20 s. Translocation was abolished by a phospholipase C inhibitor and by an antagonist against the dopamine 1 subtype (D(1)) but not the 2 subtype of receptor (D(2)). In conclusion, this study visualizes in renal epithelial cells a very rapid activation of the PKC-alpha and -epsilon isoforms by the D(1) receptor subtype.

Animals↗
PubMed2000

Arachidonic acid metabolic pathways regulating activity of renal Na(+)-K(+)-ATPase are age dependent.

Locally formed arachidonic acid (AA) metabolites are important as modulators of many aspects of renal tubular function, including regulation of the activity of tubular Na(+)-K(+)-ATPase. Here we examined the ontogeny of the AA metabolic pathways regulating proximal convoluted tubular (PCT) Na(+)-K(+)-ATPase activity in infant and adult rats. Eicosatetraynoic acid, an inhibitor of all AA-metabolizing pathways, abolished this effect. AA inhibition of PCT Na(+)-K(+)-ATPase was blocked by the 12-lipoxygenase inhibitor baicalein in infant but not in adult rats and by the specific cytochrome P-450 fatty acid omega-hydroxylase inhibitor 17-octadecynoic acid in adult but not in infant rats. The lipoxygenase metabolite 12(S)-hydroxyeicosatetraenoic acid (HETE) and the cytochrome P-450 metabolite 20-HETE both inhibited PCT Na(+)-K(+)-ATPase in a protein kinase C-dependent manner, but the effect was significantly more pronounced in infant PCT. Lipoxygenase mRNA was only detected in infant cortex. Expression of renal isoforms of cytochrome P-450 mRNA was more prominent in adult cortex. In summary, the AA metabolic pathways that modulated the activity of rat renal proximal tubular Na(+)-K(+)-ATPase are age dependent.

5,8,11,14-Eicosatetraynoic Acid↗