Publications by authors named "Itzhak Ofek"

Background: Type 2 diabetes (T2D) is a polygenic metabolic disease, characterized by high fasting blood glucose (FBG). The ability of cranberry (CRN) fruit to regulate glycemia in T2D patients is well known. Here, a cohort of 13 lines of the genetically diverse Collaborative Cross (CC) mouse model was assessed for the effect of non-dialyzable material (NDM) of cranberry extract in lowering fasting blood glucose.

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The non-dialyzable material (NDM) of polyphenol-rich cranberry extract (CRE) powder (NDM-CRE) was studied for its effect of inducing body weight (BW) loss in 13 different mouse lines with well-defined genetically diverse backgrounds, named the collaborative cross (CC). From the age of 8 weeks, the mice were maintained on a high-fat diet (HFD) for 18 weeks, to induce obesity, and BW was measured biweekly. From week 12, CRE was injected intraperitoneally (IP) (50 mg kg) 3 times a week per mouse for a 6 week period.

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The present study investigated the compounds present in the low molecular mass fraction of Lentinus edodes mushroom (shiitake) extract and their anti-virulence activity against oral pathogens (reference and clinical Streptococcus mutans, Actinomyces naeslundii, and Prevotella intermedia strains). Oxalic, succinic, and quinic acids, and adenine, inosine, and uridine were identified by HPLC-DAD-ESI-MS/MS. Their anti-biofilm production and preformed biofilm disaggregation activities were studied using commercial standard compounds at different concentrations.

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Background: In previous works we have shown that a low-molecular-mass (LMM) fraction from mushroom (Lentinus edodes) homogenate interferes with binding of Streptococcus mutans to hydroxyapatite and Prevotella intermedia to gingival cells. Additionally, inhibition of biofilm formation of both odonto- and periodonto-pathogenic bacteria and detachment from preformed biofilms have been described for this compound. Further purification of mushroom extract has been recently achieved and a sub-fraction (i.

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Polymethylmethacrylate (PMMA) impregnated with antibiotics is widely used in the treatment of osteomyelitis and infected arthroplasties. With the emergence of resistant bacterial strains, linezolid, which is active against gram-positive bacteria and toward which resistance has been scarce, has been suggested as an alternative. In the current in vitro study, the authors sought to determine and compare the efficacy and elution kinetics of linezolid from PMMA.

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Article Synopsis
  • Dental caries is an infectious disease caused by the accumulation of dental plaque, leading to the demineralization of tooth enamel and dentine, with studies identifying foods that have antibacterial properties against this condition.
  • Research focused on low-molecular-mass (LMM) extracts from edible mushrooms and Italian red chicory, evaluating their effectiveness against the bacteria Streptococcus mutans, responsible for dental caries.
  • The LMM mushroom extract showed the strongest antibacterial activity, primarily inhibiting DNA synthesis and causing morphological changes in S. mutans cells, alongside significant alterations in the membrane and cytosol proteins, indicating a potential for these extracts as safe alternative treatments for dental caries.
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Cranberry juice contains high molecular weight non-dialyzable material (NDM) which was found to inhibit hemagglutination induced by the influenza virus (IV) as well as to neutralize the cytotoxicity of IV in cell cultures. Because influenza virus surface glycoproteins hemagglutinin (HA) and neuraminidase (NA) are involved in viral replication and in the infectious process, we sought in the present study to examine the effect of NDM on neuraminidases which are the target of most anti-influenza drugs today. NDM inhibited the NA enzymatic activity of influenza A and B strains as well as that of Streptococcus pneumoniae.

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Previous studies demonstrated that a cranberry high-molecular-mass, nondialyzable material (NDM) can inhibit adhesion of numerous species of bacteria and prevents bacterial coaggregation of bacterial pairs. Bacterial coaggregation leads to plaque formation leading to biofilm development on surfaces of oral cavity. In the present study, we evaluated the effect of low concentrations of NDM on Streptococcus gordonii metabolic activity and biofilm formation on restorative dental surfaces.

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Article Synopsis
  • In vitro studies show that cranberry and its proanthocyanins can help prevent pathogens from attaching to and forming biofilms on tissues.
  • Various cranberry products have been found beneficial in reducing urinary tract infections in both young and elderly women and assist in treating Helicobacter pylori infections alongside antibiotics.
  • Further research is needed to isolate and identify the active components of cranberry for use in foods and products where whole juice or powder might not be practical.
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Purpose: To assess the effects of NDM from cranberries on Staphylococcus epidermidis biofilm formed on soft contact lenses.

Methods: Soft contact lenses were incubated in Tryptic Soy Broth (TSB) together with S. epidermidis (ATCC35984/RP62A) and various concentrations of NDM, and inspected by scanning electron and confocal microscopy.

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Cranberry has been proposed as an anti-biofilm agent that does not kill bacteria, but rather prevents the pathogen from survival in the host. This can be achieved by inhibiting the function of virulent factors essential for the pathogen to persist in a host environment. The oral bacterial enzyme fructosyltransferase (FTF) plays an important role in the pathogenesis of dental diseases.

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Background: The NH(2)-terminal sequence of the M protein from group A streptococci defines the serotype of the organism and contains epitopes that evoke bactericidal antibodies.

Methods: To identify additional roles for this region of the M protein, we constructed a mutant of M5 group A streptococci expressing an M protein with a deletion of amino acid residues 3-22 (DeltaNH(2)).

Results: M5 streptococci and the DeltaNH(2) mutant were resistant to phagocytosis and were similarly virulent in mice.

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Sporadic isolates of carbapenem-resistant KPC-2-producing Klebsiella pneumoniae were isolated in Tel Aviv Medical Center during 2005 and 2006, parallel to the emergence of the KPC-3-producing K. pneumoniae sequence type 258 (ST 258). We aimed to study the molecular epidemiology of these isolates and to characterize their bla(KPC)-carrying plasmids and their origin.

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Objectives: An extremely drug-resistant (XDR) clone of KPC-3-producing Klebsiella pneumoniae emerged in Israel in 2006, causing a nationwide outbreak. We aimed to characterize the local KPC-3-encoding plasmid carried by these isolates and study its contribution to antibiotic resistance.

Methods: Mechanisms of carbapenem resistance were investigated in seven selected isolates (isolated between 2006 and 2008) belonging to the epidemic clone.

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Cranberry juice has long been recognized in folk medicine as a therapeutic agent, mainly in urinary track infections. It acts as an antibiofilm agent against various pathogens. Quorum sensing is process where bacteria communicate with each other via signal molecules known as autoinducers.

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Context: Cranberry juice has long been recognized in folk medicine as a therapeutic agent, mainly in urinary tract infections. Its proposed mechanism of action is antiadhesion of bacteria.

Objective: Investigation of the potential antiadhesion effect of nondialyzed material of cranberry (NDM) via its influence on secretion, gene expression, and promoter activity of the fructosyltransferase (FTF), which is among the extracellular enzymes associated with dental biofilm formation and pathogenesis of oral bacteria.

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Ertapenem resistance in Klebsiella pneumoniae is rare. We report on an ertapenem-nonsusceptible phenotype among 25 out of 663 (3.77%) extended-spectrum-beta-lactamase (ESBL)-producing K.

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Background: Hydrophobicity is an important attribute of bacteria that contributes to adhesion and biofilm formation. Hydrophobicity of Streptococcus pyogenes is primarily due to lipoteichoic acid (LTA) on the streptococcal surface but the mechanism(s) whereby LTA is retained on the surface is poorly understood. In this study, we sought to determine whether members of the M protein family consisting of Emm (M protein), Mrp (M-related protein), Enn (an M-like protein), and the streptococcal protective antigen (Spa) are involved in anchoring LTA in a manner that contributes to hydrophobicity of the streptococci and its ability to form biofilms.

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We tested the relationship between the capsular and the O-antigen structures and the ability of bacteria to trigger respiratory burst in human polymorphonuclear leukocytes (PMNL). Capsulated and non-capsulated variants as well as capsule-switched derivatives of Klebsiella serotypes bearing or lacking manno(rhamno)biose repeats in their capsular polysaccharides and expressing either mannose-rich or mannose-poor O antigens were tested for their ability to induce respiratory burst and survive in human PMNL. Luminol-enhanced chemiluminescence (CL) was measured to quantify respiratory burst.

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In the present study, we found that lipoteichoic acid (LTA) synergizes with glycosphingolipids to stimulate human blood cells to secrete cytokines. We employed globoside, kerasin, and lactosylceramide as representative neutral glycosphingolipids and mixed gangliosides GM(2) and GM(3) as representative acidic glycosphingolipids. LTA and the glycosphingolipids enhanced cytokine secretion by human whole blood, peripheral blood mononuclear cells, and purified monocytes in a dose-dependent manner.

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Cranberry constituents are known to exert anti-adhesion activity on H. pylori in vitro. To determine their possible additive effect to triple therapy with omeprazole, amoxicillin and clarithromycin (OAC), a double-blind randomized clinical study was carried out.

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Macrophage stimulation by lipoteichoic acid (LTA) and hemoglobin (Hb) requires Toll-like receptors 2 and 4 (TLR2 and -4). There are two distinct temporal phases of interleukin-6 (IL-6) production. The first results in a slight enhancement of IL-6 secretion in response to LTA plus Hb compared to that with LTA alone and is TLR4 independent.

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(13)C-urea breath test (UBT) for the diagnosis of Helicobacter pylori requires a high density and active bacteria and has the potential to provide a noninvasive index of bacterial growth. We describe the gender differences in delta over baseline (13)C-UBT values in 7373 patients (4531 females and 2842 males) who underwent (13)C-UBT test for the diagnosis of H. pylori infection.

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