Effect of linezolid alone and in Combination with other antibiotics, on methicillin-resistant staphylococcus aureus

The prevalence of methicillin-resistant Staphyloccoccus aureus [MRSA] strains has presented a new challenge in antimicrobial medication. Linezolid is a new drug with potent activity on Grampositive pathogens such as MRSA. The aim of the study was to investigate the in vitro activity of linezolid alone and in combination with imipenem, vancomycin or rifampicin to determine the most active therapy against MRSA strains. Twenty clinical MRSA strains were isolated from patients admitted to inpatient departments and outpatient clinics of Theodor Bilharz Research Institute. Standard strain MRSA ATCC 43300 was included as a control. The MICs of MRSA strains to linezolid, vancomycin, imipenem and rifampicin were evaluated using E test. Time-kill curve were used to assess the in vitro activity of linezolid [at 8x MIC] alone and in combination with imipenem [at 32x MIC], vancomycin or rifampicin [at 8x MIC]. Scanning and transmission electron microscopy were performed to compare bacterial morphological alterations owing to the different combinations. Time-kill studies showed synergistic effect when linezolid combined with imipenem was tested against all the MRSA strains. Linezolid plus vancomycin or rifampicin combinations did not display any synergism or antagonism. Scanning and transmission electron microscopy observations confirmed the interactions observed in time kill experiments. Linezolid in combination with subinhibitory concentrations of imipenem can be bactericidal against MRSA strains and appears to be a promising combination for the treatment of MRSA infections. No synergistic activity was seen when the linezolid and vancomycin or rifampicin were combined. Linezolid could prevent the emergence of mutants resistant to rifampicin

Ultrastructural study of human umbilical cord blood Buffy coat and Wharton's Jelly cells

Human umbilical cord [UC] has been a tissue of increasing interest in recent years. Umbilical cord blood [UCB] was used in the treatment of several hematological diseases. New potential uses of cord blood in nonhematopoietic applications are now proposed. Lately, the Wharton's jelly [WJ], the embryonic mucuos connective tissue of the UC, with its mesenchymal stromal cells represents a promising source of cells for several regenerative therapies. This study aims to highlight the morphological ultrastustural characteristics of the UCB buffy coat and the WJ stromal cells in situ. Tiny specimens from the UCB buffy coat and the WJ were double-fixed with glutaraldehyde and osmium tetroxide, dehydrated, and embedded in epoxy resin. Ultrathin sections were cut and stained with uranyl acetate and lead citrate. Transmission electron microscopic examination [TEM] of the UCB buffy coat cells showed immature cellular constituents and few changes in the ultrastructural morphology of cord blood platelets. These ultrastructural changes may clarify the specific cultural, immunological and regenerative properties attributed to cord blood in comparison to bone marrow or peripheral blood. Wharton's Jelly TEM showed stromal cells exhibiting morphological resemblance with both fibroblasts and smooth muscle cells. In addition, cells resembling stellate cells exhibiting intracytoplasmic lipid globules and ultrastructural properties related to protein synthesis were discerned. Also, oval cells with primitive nuclear and cytoplasmic features pointing to a subpopulation with stem cell potency were seen. We suggest that the WJ contains several distinct populations of stromal cells with different potentials including a primitive subpopulation. We propose that the nomenclature of these cells should not only be linked to their morphological appearance but also to their specific functional properties. Extensive in situ and in vitro molecular, immunohistochemical and immuno electron microscopic studies are necessary to clearly identify these cell populations with different potentials

Angiogenic potential of human umbilical cord blood ex vivo expanded CD 133* stem cells in chronic hepatic fibrosis of murine schistosomiasis

As a source of hematopoietic stem cells [HSCs], umbilical cord blood [UCB] has the advantages of speed of availability, tolerance of more than one HLA mismatch, and a low incidence of severe graft-versus-host disease [GVHD]. Hence, it represents a promising, alternative non-costly and non-invasive source for prospective stem cell based therapy. In this study we investigated the angiogenic potential of ex vivo expanded human umbilical cord blood CD 133* stem cells transplanted into mice with chronic hepatic fibrosis induced by Schistosomiasis infection. Histopathological, ultrastructural and immunohistochemical analysis of mice liver sections were done to detect specific human angiogenic markers. Umbilical cord blood was obtained from healthy pregnant females after delivery and mononuclear cells were collected by density gradient using Ficoll Hypaque. Enrichment for the CD 133* stem cells was done by positive selection using the Magnetic Activated Cell Sorting system and magnetic microbeads. Cells were cultured in prirnaly ex vivo expansion medium for three weeks. Flowcytomeric analysis of the cultured cells was done in each step to identify the CD 133* cells. Schistosomiasis was induced in Swiss Albino mice by intradermal injection of schistosoma cercariae. Twenty two weeks post schistosoma infection a total of 0.3 x 106 human CD 133* stem cells were injected intrahepatically in mice. Accordingly, mice were divided into three groups: Group 1 [infected, transplanted]; Group 2 [infected controls] and Group 3 [healthy, transplanted]. All mice were sacrificed 3 wks after cell transplantation was done in groups I and 3. Histopathology and Electron microscopy showed an obvious increase in the capillary network and the small blood vessels and a decrease in the fibrosis known for this stage of the disease. By immunohistochemical analysis the cellular constituents of these newly formed blood vessels showed positive expression of the human-specific angiogenic markers CD31, CD34 and von Willebrand Factor [vWF]. Few hepatocyte like polygonal cells showed positive expression of human Vascular Endothelial Growth Factor [VEGF] and inducible Nitric Oxide Synthase [iNOS]. Ex vivo expanded CD 133* human stem cells incorporate into the liver of schistosoma infected mice enhancing local angiogenesis and hepatic neovascularization. These preliminary results obtained suggest a dual benefit of CD 133* cells in cell therapy in hepatic diseases based on its capability of hematopoietic and endothelial differentiation. We suggest that the CD 133* cells contribute to repair in a paracrine manner by creating a permissive environment that enables rapid proliferation and survival of damaged cells rather than through direct differentiation to hepatocytes

Ultrastructure and types of fimbriae in uropathogenic E-coli among bilharzial patients

The aim of this work was to study the association of different types of fimbriae of urinary E coli isolates with different disease entities. We collected a total of 57 urinary E. coli isolates from 3 groups of bilharrzial patients: group 1: with cystitis [21 isolates]; group 2: with pyelonephritis [18 isolates] and group 3: with urinary bladder carcinoma [18 isolates]. Each isolate was studied for: I. Fimbrial expression and type determination by haemagglutination [HA] of human and guinea pig erythrocytes. II. Electron microscopic [E/M] structure using negative staining, standard transmission and scanning electron microscopy. It was found that infection with mannose sensitive type 1 fimbriated E. coli dominated in group 1 and 3 [80.95% and 77.78% respectively]. In group2 [55.56%] were caused by mannose resistant P fimbriated E. coli. Although there was a perfect correlation between HA and the presence of fimbiriae by E/M [P< 0.01], yet E/M detected other types of fimibriae which could-have been missed by HA alone. Negative staining was the best technique in electron microscopy. We concluded that detection of P flimbriae in urinay E. coli strains may justify a vigorous antibiotic treatment to prevent development of pyelonephritis. Although type 1 fimbriae was associated with simple cystitis, yet follow up and complete investigations are recommended to detect an associated carcinoma

Soluble P-and E- selectins and ultrastructural evaluation of canine liver after reperfusion with methylprednisolone and prostaglandin E 1

Ischemia reperfusion injury [IRI] is a multifactorial process that may be the main underlying factor in critical phases faced during and after liver transplantation. This work evaluates the effect of methylprednisolone [MP] and prostaglandin El [PGE1] on IRI of the liver of dogs at the ultrastructural level together with the assessment of soluble P-and E- selectin levels. Three groups of dogs [9 each] were subjected to 60 min ischemia followed by 30 min reperfusion with the appropriate solution according to the group. Group I, the control untreated group was flushed with Ringer's solution, group II was administered 10 mg/kg MP 24 hours before the procedure and with induction of anaesthesia, and group III was flushed with PGE1 in Ringer's solution at a rate of 0.02 microg/kg/min. Liver specimens were collected before ischemia, after ischemia and after reperfusion and were processed for the preparation of ultrathin sections for electron microscopic examination. Corresponding venous blood samples were harvested, centrifuged and serum was processed for the estimation of soluble P-and E- selectins by enzyme immunoassay, together with alanine and aspartate aminotransferases. Electron microscopic [EM] examination of liver ultrathin sections revealed that the morphological structure of hepatocytes and endothelial lining of hepatic sinusoids were well preserved in the group treated with PGE1. Hepatic ultrastructure was much altered in MP treated group showing necrotic and degenerative changes. The control untreated group disclosed bleb formation of hepatocytic membrane with increased leukocyte infiltration. Soluble P-and E- selectin levels were significantly elevated in the control group, near to pre-ischemic level in PGE1 group and showed a persistent elevation in MP group. Serum transaminases [AST and ALT] were significantly elevated in both control and MP groups as compared to their corresponding pre-ischemic levels. Yet, in PGE1 group, their values were comparable to the pre-ischemic ones. This work confirms the hepatoprotective effect of PGE1 in IR injury. The PGE1 impact on preserving the subcellular structure of hepatic sinusoids is crucial and may be mainly attributed to its biological properties. We presume that P-and E- selectins are greatly implicated in the mechanism of IR and may be an important therapeutic target by specific monoclonal antibodies

Ultrastructure and types of fimbriae in uropathogenic E-coli among bilharzial patients

The aim of this work was to study the association of different types of fimbriae of urinary E coli isolates with different disease entities. We collected a total of 57 urinary E. coli isolates from 3 groups of bilharzial patients: group 1: with cystitis [21 isolates]: group 2: with pyelonephritis [18 isolates] and group 3: with urinary bladder carcinoma [18 isolates]. Each isolate was studied for: I-fimbrial expression and type determination by haemagglutination [HA] of human and guinea pig erythrocytes, II- Electron microscopic [E/M] structure using negative staining, standard transmission and scanning electron microscopy. It was found that infection with mannose-resistant type I fimbriated Ecoli dominated in group 1 and 3 [80.95% and 77.78% respectively]. In group 2. 55.56% were caused by man- nose resistant P fimbriated Ecoli. Although there was a perfect correlation between HA and the presence of fimbriae by E/M [p< 0.01], yet E/M detected other byres of fimbriae which could have, been missed by HA alone. Negative staining was the best technique in electron microscopy. We concluded that detection of P fimbriae in urinay Ecoli strains may justify a vigorous antibiotic treatment to prevent development of pyelonephritis. Although type I fimbriae was associated with simple cystitis, yet follow up and complete investigations are recommended to detect an .associated carcinoma

Octreotide decreases connective tissue formation and improves vascular changes associated with hepatic schistosomiasis

The present work was undertaken to investigate the possible use of Octreotide as an antifibrotic agent and to study its effect on hepatic vasculature in Schistosoma mansoni infection. Two groups of albino mice [A and B], each subdivided into normal control, infected control, Octreotide treated, praziquantel treated and Octreotide with Praziquantel treated subgroups. were included in the study. Groups A and B were sacrificed at the 8th and 18th weeks post-infection, respectively. By analysis of the obtained results, Octreotide has induced reduction in the portal pressure, the weight of the spleen and the liver, the number of liver egg load, granuloma size and cellularity as well as the degree of hepatic fibrosis quantified by serum PIIINP, serum laminin and tissue collagen using sirius red dye assay. Moreover, the biochemical state of hepatocytes has been improved. The subgroups treated with Octreotide in association with Praziquantel revealed better results than the subgroups treated with Praziquantel alone. Data were analyzed in terms of histological extent of liver fibrosis in sections stained with Masson trichrome and sirius red, hepatocytic and sinusoidal changes at an ultrastructural level and by immunohistochemical demarcation of endothelial cells of blood vessels, through the determination of factor VIII related antigen. The promising results detected in this study may encourage to further investigate the positive findings of this drug with the intention of its possible application on a clinical level