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Biomedical subjects

E Segal

Publications and source records attributed to E Segal.

At least 109 records · Page 6Linked to original sources
PubMed1989

QRS-activated ventilation during general anesthesia for extracorporeal shock wave lithotripsy.

High frequency ventilation has been claimed to improve the efficiency of extracorporeal shock wave lithotripsy (ESWL) by minimizing the movement of urinary stones during the procedure. A ventilatory mode, QRS-activated ventilation, was developed in which the stones remain motionless during the delivery of shock waves. As the shock wave is triggered to occur approximately 20 milliseconds after the R wave of the QRS complex, the mechanical breath was synchronized to occur approximately 150 ms later. QRS-activated ventilation is used in 16 patients undergoing ESWL under general anesthesia. Tidal volume was set at 3 ml/kg (234 +/- 36 ml; mean +/- SD) at a rate that equaled the heart rate (71 +/- 9 beats/min). The time between the R wave and the initiation of mechanical breath (T1) was 124 +/- 25 ms, time of mechanical breath itself (T2) was 431 +/- 67 ms, and time between end of T2 and next R wave (T3) was 264 +/- 84 ms. End-tidal CO2 measured by the large breath technique was 28.1 +/- 4.8 mmHg. During the clinical use of QRS-activated ventilation and during earlier studies using an EKG simulator and a test lung, the shock wave occurred invariably at end-expiration even at high heart rates.

Adult↗
PubMed1989

Biotyping of Candida albicans: results of an international collaborative survey.

An agar plate system for biotyping isolates of Candida albicans was evaluated in four laboratories for 18 coded yeast isolates, each tested in triplicate on duplicate series of agar plates. The results showed that the biotyping system gave excellent intralaboratory reproducibility. However, because the concordance of data among laboratories was poor, the method must be regarded as suitable only for research applications and not for routine use.

Candida albicans↗
PubMed1989

Interaction of Candida albicans with murine gastrointestinal mucosa: effect of irradiation on adherence in vitro.

The aim of this study was to investigate the adherence in vitro of Candida albicans to various parts of the gastrointestinal (GI) mucosa from irradiated and non-irradiated mice and to attempt to inhibit this adhesion with a chitin derivative. Adhesion was assayed using 3H-leucine labelled yeast, to which GI tissue-disks removed from irradiated (400R Cobalt) and non-irradiated animals were exposed at various time intervals post-irradiation. In non-irradiated mice differences in adherence of C. albicans to various parts of the GI tract were observed, the highest adherence being to duodenal tissues. In irradiated mice, an increase in adherence to all parts of the GI mucosa was observed. Based on findings from previous studies that a chitin derivative (CSE) inhibits adhesion of C. albicans to various tissues in vitro and in vivo, we tested the effect of CSE on the adhesion of C. albicans to GI tissues. The results show that CSE inhibited the adhesion of C. albicans to GI tissues from both irradiated and non-irradiated mice by 75-85%. The relevance of the findings to the pathogenesis of candidiasis is discussed.

Animals↗
PubMed1988

Candidal vaginitis in hormone-treated mice: prevention by a chitin extract.

In view of findings from previous studies that a chitin soluble extract (CSE) blocked adhesion of Candida albicans in vitro and in vivo and prevented thereby a short lived candidal infection in naive mice, we attempted in the present study to block by CSE the development of a persistent infection, induced in hormone-treated animals. Continuous oestrus phase was obtained in mice by repeated weekly subcutaneous injections with estradiol benzoate. Intravaginal inoculation of the hormone-treated mice with 10(7)-10(10) C. albicans cells induced a persistent candidal infection. Fifty three mice were pretreated intravaginally prior to inoculation of C. albicans with 2.5, 5.0 or 10 mg/mouse of a CSE cream and followed up for development of infection in comparison to 30 untreated animals. Twenty four hrs post fungus inoculation the infection rate among the CSE treated mice was 11-23% VS 84% among the controls; the rate increased a week later to 97% among the controls VS 41-50% among the CSE treated. Administering the CSE to the mice prior--and post-yeast inoculation (37 mice), led to increased efficacy of the treatment. The data, indicating that CSE is an effective measure for preventing persistent candidal vaginitis, may open the way to consider a similar approach for prophylaxis of vaginitis in human susceptible populations.

Animals↗
PubMed1988

Effect of Candida albicans cell wall components on the adhesion of the fungus to human and murine vaginal mucosa.

In this study, cell walls from Candida albicans were separated and chitin was isolated from these cell walls. A chitin soluble extract (CSE) prepared from the chitin inhibited in vitro adhesion of C. albicans to human epithelial vaginal cells (VEC), and blocked in vivo attachment to murine vaginal mucosa, thereby preventing candidal infection in these animals. These findings suggest that the CSE acts as an adhesin-like substance. Fractionation of CSE yielded two fractions: FI and FII, of which only FI exhibited inhibitory activity. Chemical analysis of CSE and its two fractions revealed that CSE contains over 70% of proteins, most of which were found in the non-active fraction. In addition, 3% of amino-sugars were found in the FI active fraction. Lipids were also detected in the unfractionated CSE and in both fractions. Experiments to further characterize the component(s) in the CSE inhibiting the attachment of C. albicans are in progress in our laboratory.

Animals↗
PubMed1988

Adherence in vitro of various Candida species to acrylic surfaces.

Adherence of microorganisms to the surfaces of the host is believed to be an initial and essential step in the production of infection. The objective of the present study was to compare the adherence in vitro of 17 isolates of various Candida species to acrylic surfaces. The results showed that all 17 Candida strains adhered to acryl. Generally, all Candida albicans strains were more adherent than the other strains of Candida species that were tested. Marked differences in the adherence ability of strains belonging to the same species were noted. Future studies to search for possible association between adherence of Candida strains to acryl and pathogenesis of denture stomatitis are planned.

Acrylic Resins↗
PubMed1988

Developmental regulation of the cysteine-rich outer-membrane proteins of murine Chlamydia trachomatis.

The developmental cycle of the obligate intracellular prokaryote Chlamydia trachomatis involves the serial alternation of two distinct morphological forms of the organism. To examine the basis of chlamydial differentiation we have searched for developmentally regulated gene products in this species. Chlamydia-infected cells were pulse-labelled with [35S] cysteine at various stages of development and the products of synthesis examined by SDS-PAGE. Our results indicate that the synthesis of the cysteine-rich outer-membrane proteins is developmentally regulated, occurring only late in the cycle during the conversion of reticulate bodies to elementary bodies. Both hydroxyurea and ampicillin block this conversion; as a result of this blockade the cysteine-rich outer-membrane proteins are not produced in the presence of either drug.

Ampicillin↗
PubMed1988

Interaction of Candida albicans with genital mucosa: effect of sex hormones on adherence of yeasts in vitro.

Findings from our previous studies revealed a correlation between the level of adherence in vitro of Candida albicans to human exfoliated vaginal epithelial cells (VEC) and the hormonal status of the cell donors. In the present study we investigated the effect of the sex hormones estradiol, estriol, progesterone, and testosterone on the binding of the yeasts to HeLa cell lines and VEC in vitro. Monolayers of HeLa cells were exposed to the hormones and yeasts under controlled conditions. The number of adherent yeasts per square millimetre of HeLa cell monolayers and the percentage of VEC with adherent yeasts was estimated by microscopic counts. The results showed that the tested sex hormones affected at various degrees the adhesion of yeasts to HeLa cells or VEC. Progesterone had the most marked effect, leading to a significant increase in the number of adherent yeasts to HeLa cells or in the percentage of adhesion of VEC. In addition, VEC were separated on Percoll gradients into the two cell types: superficial (S) and intermediate (I), cell types which appear physiologically under increased serum levels of estradiol or progesterone, respectively. Adhesion assays with the separated cell populations revealed an increased binding capacity of the I cells. The finding that progesterone increased the adherence of yeasts to genital mucosa and that VEC of the I type have a higher capacity to adhere the yeasts is compatible with our previous observation that increased numbers of I cells, appearing under high level of progesterone, are found in situations known to have predisposition to vaginal candidiasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Candida albicans↗
PubMed1988

In vitro adherence of Candida albicans to human corneocytes. Inhibition by chitin-soluble extract.

In vitro adherence of Candida albicans to human corneocytes and the effect of a chitin-soluble extract (CSE) on the adherence reaction were studied. Adherence of the yeasts to cells obtained from different individuals was variable. However, repeated adherence tests with pooled corneocytes of 2 individuals from this group showed that the adherence parameters did not differ greatly throughout these tests. CSE at the concentration of 50 mg/ml had a significant inhibitory effect on the attachment of C. albicans to the corneocytes, most probably by blocking their receptors of attachment. The data indicate that the preparation may be useful in the prophylactive management of recurrent cutaneous candidiasis in susceptible individuals.

Adhesiveness↗
PubMed1987

Vaccines against fungal infections.

The state-of-the-art reached in developing protective immunity against fungal infections through vaccination makes a survey of methodologies and results timely. This review describes experimental vaccinations against dermatophytes, pathogenic yeasts, and dimorphic fungi with special attention to the anti-Coccidioides immitis vaccine, which has reached clinical trials, and to the anti-Candida albicans and anti-Histoplasma capsulatum ribosomal vaccines. Also covered are vaccination experiments in compromised hosts aimed at eliciting acquired resistance to opportunistic fungal infections which constitute risk factors for these hosts. Immunization procedures include live, killed, and attenuated organisms, as well as different subcellular fractions such as cytoplasmic extracts, fungal culture filtrates, cell walls, or ribosomal fractions. A variety of experimental animal models and isolated human trials constitute the subjects in these studies. Acquired immunity has been evaluated through assessment of resistance to infection and determination of specific immune responses. It has been demonstrated that fungal vaccines do elicit both humoral and cell-mediated immunity in the immunized host. For some vaccines (e.g., H. capsulatum), a correlation between the induced immunity and protection was observed and the immunity could be adoptively transferred. In view of the potential of vaccines against fungal infections, a perspective on their applicability, significance, and value for human use is discussed.

Animals↗
PubMed1987

Pathogenesis of human mycoses: role of adhesion to host surfaces.

Adhesion of microorganisms to various mucosal surfaces appears to be essential for initiating infection. The role of adhesion to host surfaces in pathogenesis of human mycoses, particularly the various manifestations of candidiasis, has been shown experimentally and correlated with epidemiological data.

Candida↗
PubMed1987

Induction of protection against candidiasis in tumor-bearing mice by vaccination with Candida albicans ribosomes.

The aim of this study was to determine whether vaccination of tumor-bearing mice with ribosomes of Candida albicans would result in the induction of protective immunity. Therefore, (BB)F1 mice were inoculated intraperitoneally with the thymoma, EL-4, then immunized with ribosomes purified from C. albicans, and challenged intravenously with C. albicans to assess the protective response. Unimmunized mice, both normal and tumor-bearing, treated in the same manner served as controls. Both normal and tumor-bearing mice developed protective immunity in response to immunization with ribosomes. The protected mice had fewer colony-forming units in their kidneys 3 days after intravenous challenge than the unimmunized control animals, regardless of tumor status. Moreover, all unimmunized mice, tumor-bearing and normal, developed delayed hypersensitivity to the ribosomes, as well as ribosome-specific antibody, both of which were of the same order of magnitude. Therefore, the EL-4 thymoma does not suppress the immune system of mice, and they are capable of responding immunologically in a normal manner to C. albicans.

Animals↗
PubMed1986

Relationship between cellular diadenosine 5',5'''-P1,P4-tetraphosphate level, cell density, cell growth stimulation and toxic stresses.

In order to elucidate the postulated role of diadenosine 5',5'''-P1,P4-tetraphosphate (Ap4A) in cell growth regulation, the Ap4A cellular content was measured in cells submitted to various treatments affecting the cell growth. Ap4A level was found to increase ten times when cells reached confluence, whereas no significant variation of the ATP pool was observed. Cell growth arrest after serum depletion did not cause any variation in the Ap4A pool. A limited increase in the Ap4A pool was observed when growth of arrested cells was reinitiated but this variation reflected only the increase of cell density. No significant variation in the Ap4A intracellular level was observed after submitting two eukaryotic cell lines to various stresses (cytotoxic drugs, ethanol and heat-shock treatments). These results suggest that, in eukaryotic cells, Ap4A is not involved in cell growth stimulation but rather is associated with cell contact growth inhibition. They also suggest that Ap4A is not an 'alarmone', contrary to what has been proposed for bacteria.

Adenine Nucleotides↗