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Biomedical subjects

M B Goren

Publications and source records attributed to M B Goren.

At least 37 records · Page 2Linked to original sources
PubMed1988

Diagnostic tests in patients with symptoms of keratoconjunctivitis sicca.

We compared the relative value of the tear film breakup time, Schirmer test, lactoferrin immunologic assay and rose bengal staining in 156 patients with varying severity of symptoms characteristic of keratoconjunctivitis sicca and in 39 controls. Statistical analysis showed that in patients with minimal ocular irritation the Schirmer test in combination with the lactoferrin immunologic assay provided an optimal balance between high test sensitivity and low false-positive rates. In patients with moderate to severe ocular burning, foreign body sensation, or pain but with no systemic symptoms of dry mouth or arthritis, and in patients with both ocular and systemic complaints, the lactoferrin assay alone provided statistically significant results. Tear film breakup time and staining with rose bengal were not useful and the Schirmer test had limited value in measuring the rate of tear secretion in these patients.

Adult↗
PubMed1988

Mycobacterium lepraemurium activates macrophages but fails to trigger release of superoxide anion.

Mycobacterium lepraemurium failed to stimulate a normal respiratory burst when presented to mouse peritoneal or bone marrow macrophages. By comparison, Mycobacterium bovis (strain Bacillus Calmette-Guerin) or Saccharomyces cerevisiae, as expected, stimulated macrophages to release a large amount of superoxide anion (O2-). M. lepraemurium did not interfere with the response to yeast when both microbes were added together to macrophages. The low release of O2- induced by M. lepraemurium was not due to failure of M. lepraemurium to activate or prime macrophages, because exposure of macrophages to M. lepraemurium caused the expected enhancement of O2- release when the macrophages were stimulated by PMA. Similarly, macrophages taken from mice infected with M. lepraemurium were activated, as indicated by high PMA-stimulated O2- release. Macrophages primed in vitro by exposure to Escherichia coli LPS for 24 h did show a moderate O2- response when stimulated by M. lepraemurium, but macrophages primed by exposure to IFN-gamma muramyl dipeptide, or M. lepraemurium showed a weak response when subsequently challenged with M. lepraemurium. The priming effect of M. lepraemurium or LPS decreased substantially after macrophages were cultured in fresh medium for 24 h. Heat killing or opsonization of M. lepraemurium caused the M. lepraemurium to stimulate a high amount of O2- release from LPS-primed macrophages, but heat killing or opsonization of M. lepraemurium had no effect on release of O2- from unprimed macrophages. The results suggest that M. lepraemurium is taken into macrophages by a mechanism that bypasses the FcR and other receptors that are capable of triggering the production of O2-.

Animals↗
PubMed1988

Concerning hydrolysis of mycolate esters, of phthiocerol dimycocerosates and of related mycobacterial lipids: an anecdotal account.

We review the experimental difficulties that have been encountered in hydrolyzing mycolic acid esters, their beta-O-substituted analogues, permethylated cord factor, phthiocerol dimycocerosates and similar mycobacterial lipids. Hydrolysis of the beta-O-substituted methyl mycolates is invariably sluggish and is accompanied by considerable beta-elimination to generate mycolenoic acids. Historical evidence for this often undesirable side reaction is presented. Improvements in methodology are described in which hydrolysis is promoted and beta-elimination is minimized. The reaction systems developed were found applicable to hydrolysis of the quite inert phthiocerol dimycocerosates. Permethylation of the recovered phthiocerol provides an excellent derivative for mass spectrometric analysis to define its complete structure.

Esters↗
PubMed1988

Inhibition of macrophage priming by sulfatide from Mycobacterium tuberculosis.

Sulfatide from the outer surface of Mycobacterium tuberculosis blocked priming in cultured human monocytes. Monocytes were primed in vitro with either lipopolysaccharide (LPS) or interferon-gamma. Primed monocytes released increased amounts of superoxide anion (O2-) when stimulated with formyl-methionyl-leucyl-phenylalanine or with phorbol myristate acetate. Primed monocytes also showed increased phagocytosis of sheep erythrocytes and increased release of interleukin 1. When primed monocytes were treated with 10 micrograms/ml of sulfatide, these enhanced functions, characteristic of primed monocytes, returned to levels found in unprimed monocytes. (With respect to these functions and others, monocytes or macrophages primed in vitro by exposure to LPS or interferon-gamma resemble macrophages activated in vivo by infection. In vivo, activated macrophages provide non-specific resistance to infection). Inhibition of priming by sulfatide could be detected within 10 min, but maximum effect of sulfatide required 3 to 5 hr. Sulfatide had no effect on O2- release, if it was added after the cells had been stimulated by PMA, suggesting that sulfatide did not inhibit enzymes involved in formation of O2-, but rather that sulfatide inhibited priming. Increasing the amounts of LPS or interferon-gamma did not counteract the effects of sulfatide. Sulfatide did cause monocytes to release some prostaglandin E2 (less than 1 nM), but the amount was not sufficient to inhibit monocyte functions. The effect of sulfatide was not blocked by indomethacin. Other sulfated compounds and other products of mycobacteria did not produce the sulfatide effect. We conclude that M. tuberculosis has on its outer surface a chemical that directly interferes with monocyte priming. In vivo, M. tuberculosis might use sulfatide to block macrophage activation and thereby resist being killed by macrophages.

Dinoprostone↗
PubMed1988

Effect of Mycobacterium tuberculosis-derived sulfolipid I on human phagocytic cells.

Experiments were performed to determine the effects of Mycobacterium tuberculosis-derived sulfolipid I on phagocytic cells. Sulfolipid I was taken up in significant amounts by human neutrophils and in lesser amounts by monocytes and lymphocytes. Superoxide (O2-) production by neutrophils was significantly increased by sulfolipid I, but the rate of production was slower than that reported previously for other stimuli. The optimal concentration of sulfolipid I for stimulation of O2- production was 27 micrograms/ml, while higher concentrations produced less. At substimulatory levels sulfolipid I caused enhancement of O2- release from neutrophils when it was subsequently stimulated by other agents. Nonadherent monocytes from most normal donors failed to produce O2- when treated with sulfolipid I; however, adherent monocytes pretreated with gamma interferon did produce O2- with sulfolipid I stimulation. Priming for an enhanced oxidative response of activated monocytes was also observed. These sulfolipid I-induced changes in phagocytic cell function may be important in altering the ability of phagocytes to respond effectively to M. tuberculosis and may also cause exaggerated inflammatory responses.

Cell Survival↗
PubMed1988

Pathogenesis of trehalose dimycolate-induced interstitial pneumonitis. IV. Evidence against roles for immunoglobulins and the complement system.

We showed previously that trehalose dimycolate (TDM) in oil administered intraperitoneally into susceptible mice produced interstitial and hemorrhagic pneumonitis by the seventh day after injection and that mature T cells are necessary for the production of these lesions. TDM has been reported to activate complement and to be chemotactic for macrophages in vitro. Accordingly, we looked for involvement of humoral mechanisms in the pathogenesis of TDM-induced pneumonitis. Genetically C5-deficient B10D2/oSn mice developed pulmonary lesions just as well as C5-sufficient mice. No activation of C3 occurred in the plasma of TDM-treated mice as determined by crossed immunoelectrophoresis. Some splitting of C3 occurred in bronchoalveolar lavage fluids, but this was similar in control and experimental mice. By immunofluorescence microscopy, there was no deposition of C3 or immunoglobulins (Ig) along the alveolar membranes. These findings and our published data provide additional evidence that TDM-induced interstitial inflammation in mice is exclusively a T-lymphocyte-dependent process.

Animals↗
PubMed1987

Polyanionic agents as inhibitors of phagosome-lysosome fusion in cultured macrophages: evolution of an alternative interpretation.

Various natural and synthetic substances classified as polyanionics have been implicated in antagonizing phagosome-lysosome fusion in cultured macrophages. The phenomenon has been judged by comparing the transfer of selected markers from secondary lysosomes to phagosomes in control and in "polyanion" cells. Our earlier studies showed that use of one of the markers, the membrane-permeating acridine orange, was plagued with artifacts that were especially misleading in the presence of polyanionic agents. We now question the validity of data obtained by the alternative technique, electron microscopy. Our present evidence shows that nonionic hydrocolloids of sufficiently high molecular weight prevent the transfer of various colloidal electron-opaque markers from lysosomes to phagosomes in the same manner as does the powerful polyanionic "fusion inhibitor" dextran sulfate. Both kinds of hydrocolloids, however, allow delivery of lysosomal, low-molecular-weight highly charged non-permeant fluorescent markers to phagosomes, probably by a fusion process. We propose that neither type of hydrocolloid inhibits fusion; instead, when sufficiently concentrated, they trap particulate electron-opaque markers in a gelatinous matrix, which may move only slowly out of lysosomes. The polyanionics trap the electron-opaque markers physically and acridine orange ionically. Hence, the semblance of "fusion inhibition."

Animals↗
PubMed1987

Polyanionic agents do not inhibit phagosome-lysosome fusion in cultured macrophages.

The survival of some intracellular pathogens within macrophages may be aided by an ability of the organism to antagonize, from within the entrapping phagosome, its fusion with lysosomes. On the other hand, certain polyanionic agents have been implicated in imposing a similar block to fusion from the lysosomal domain--because the transfer of various foreign markers from lysosomes to newly formed phagosomes is remarkably inhibited in these polyanion-containing cells. Based on an analysis of various observations and our own recent data, we propose that the polyanionics do not, in fact, prevent phagosome-lysosome fusion but, instead, physically entrap the usual markers in a gelatinous matrix within the lysosomes. This view accounts for many paradoxical consequences of polyanionic accumulation and for the curiously normal behavior of macrophages that are presumed to be suffering from such a crucial intracellular dysfunction.

Animals↗
PubMed1987

Differential and sequential delivery of fluorescent lysosomal probes into phagosomes in mouse peritoneal macrophages.

It has previously been inferred that the fusion of a macrophage secondary lysosome with a phagosome delivers the entire lysosomal contents uniformly to the phagosome. We found, however, that different fluorescent lysosomal probes can enter phagosomes at remarkably different rates, even though they are initially sequestered together in the same organelles. Thus, sulforhodamine is almost exclusively delivered to yeast-containing phagosomes within 2 h of phagocytosis. But fluoresceinated, high molecular weight dextran accumulates in the same phagosomes only over a period of approximately 24 h. We postulate that the delivery of lysosomal contents may involve an intermittent and incremental process in which individual components can be selectively and sequentially transferred.

Animals↗
PubMed1987

Detection of trehalose monomycolate in Mycobacterium leprae grown in armadillo tissues.

Trehalose-6-monomycolate (TMM) was isolated from the lipids of armadillo-derived Mycobacterium leprae. Only meagre amounts of this glycolipid were recovered, but its structure was unequivocally established. Only alpha-mycolates were detected in the TMM by 252Cf plasma desorption mass spectrometry. Electron impact mass spectrometry showed the alpha branch to be principally C20. Trehalose dimycolate (cord factor) was not detectable. Since we have also found TMM in M. lepraemurium and in every Mycobacterium species so far examined, we suggest that this glycolipid is truly ubiquitous amongst mycobacteria.

Animals↗
PubMed1987

Discrepancy in assessment of phagosome-lysosome fusion with two lysosomal markers in murine macrophages infected with Candida albicans.

Phagosome-lysosome fusion (P-LF) was studied in cultured mouse resident peritoneal macrophages after phagocytosis of Candida albicans. The macrophages were labeled with acridine orange (AO), the electronopaque colloidal Thorotrast, or both markers. After phagocytosis of heat-killed C. albicans, both markers were delivered to more than 95% of phagosomes. After ingestion of viable C. albicans by labeled cells, delivery of AO to phagosomes was highly suppressed (90%), and yet Thorotrast delivery was almost universal. After phagocytosis and 60 min of incubation, about 10 to 20% of the yeasts were killed, and a similar fraction of phagosomes was stained by the fluorescent marker. The evidence from Thorotrast transfer and assessment of yeast viability indicates that C. albicans largely resists intracellular killing by resident macrophages in the face of entirely uninhibited P-LF. We infer that AO must transfer to nearly all of the phagosomes but that it is evidently recognizable only in those in which the yeasts have been killed or possibly severely injured. This conclusion constitutes yet another limitation in the usefulness of AO for studying P-LF.

Acridine Orange↗
PubMed1986

Haptenic oligosaccharides in antigenic variants of mycobacterial C-mycosides antagonize lipid receptor activity for mycobacteriophage D4 by masking a methylated rhamnose.

The simple apolar C-mycosides, i.e., structurally well-defined hydrophobic glycopeptidolipids of several Mycobacterium species (see diagram below), were earlier shown to behave as receptors for adsorption of mycobacteriophage D4. This phage is usually virulent for Mycobacterium smegmatis. More complex, polar C-mycosides with additional carbohydrate substituents attached solely to the deoxytalose have recently been described. They are the highly specific serotyping antigens discovered by W. B. Schaefer--lipids which characterize members of the Mycobacterium avium-Mycobacterium intracellulare-Mycobacterium scrofulaceum (MAIS) complex. Both kinds are depicted in the structure below: (Formula: see text) where X equals H (for simple, apolar C-mycosides) and X equals small oligosaccharides (for antigenic forms; more complex, polar C-mycosides). The present investigations showed that the purified polar antigenic lipids exhibit considerably less adsorptive activity for D4 than do the apolar C-mycosides. Thus, the haptenic oligosaccharides are believed to shield the site in the molecule that the phage recognizes, and the blocking is reinforced by the specific antibodies that the antigens elicit. Although the MAIS serovars usually also produce the phage-reactive apolar C-mycosides, they are not permissive hosts for D4, nor do whole cells adsorb the phage. We suggest that in these species the apolar forms are probably "covered" at the cell surface by the antigenic lipids. Therefore, these antigenic mycosides may play a putative role in virulence of the MAIS members by protecting these mycobacteria from their own potential pathogen. The results of chemical transformations at specific sites of the mycoside core coupled with studies of simple synthetic lipid glycosides indicated that the principal phage receptor activity resides in the terminal methylated rhamnose (see diagram). It is this sugar which is evidently masked by the (seemingly remote) haptenic oligosaccharides.

Adsorption↗
PubMed1984

Cord-factor analogs: synthesis of 6,6'-di-O-mycoloyl- and -corynomycoloyl-(alpha-D-galactopyranosyl alpha-D-galactopyranoside).

Appropriate solvolysis of 2,3,2',3'-tetra-O-benzyl-4,6,4', 6'-tetra-O-mesyl-alpha,alpha-trehalose gave 2,3,2',3' -tetra-O-benzyl-(alpha-D-galactopyranosyl alpha-D-galactopyranoside) (2). Selective tosylation or mesylation of 2 respectively gave the 6, 6'-ditosylate (3) and 6,6'-dimesylate (4), the structures of which were confirmed by the 1H-n.m.r. spectra of the corresponding 4,4'-di-O-acetyl derivatives. Treatment of 3 with potassium mycolate in toluene, and subsequent hydrogenolysis, gave the 6'-mycolate 6-tosylate derivative. Treatment of 3 with potassium mycolate or potassium corynomycolate in hexamethylphosphoric triamide, followed by catalytic hydrogenolysis, yielded the respective cord-factor analogs 6,6'-di-O-mycoloyl-(alpha-D-galactopyranosyl alpha-D-galactopyranoside) and 6,6'-di-O-corynomycoloyl-(alpha-D-galactopyranosyl alpha-D-galactopyranoside). The same 6,6'-diesters were obtained from the 6,6'-dimesylate 4. Putative 4,6-anhydro-6'-monomycolates are also described.

Cord Factors↗