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Biomedical subjects

M Gustin

Publications and source records attributed to M Gustin.

13 recordsLinked to original sources
PubMed2002

[Clinical case of the month. A recurrent chylothorax in Bourneville tuberous sclerosis].

Bourneville's disease, first described in 1862, is a phacomatosis that is either autosomal dominant or sporadic. Its typical clinical signs include mental retardation, epilepsy and cutaneous adenomas. The pulmonary form is rare, less than 1%, and is secondary to occlusion of the bronchus, vascular and lymphatics by immature smooth muscle cells. Chylothorax may appear in more than 50% of all cases. No guidelines currently exist for treatment of recurrent chylothorax. However, several possibilities are described in the literature.

Adult↗
PubMed1999

Role of the mitogen-activated protein kinase Hog1p in morphogenesis and virulence of Candida albicans.

The relevance of the mitogen-activated protein (MAP) kinase Hog1p in Candida albicans was addressed through the characterization of C. albicans strains without a functional HOG1 gene. Analysis of the phenotype of hog1 mutants under osmostressing conditions revealed that this mutant displays a set of morphological alterations as the result of a failure to complete the final stages of cytokinesis, with parallel defects in the budding pattern. Even under permissive conditions, hog1 mutants displayed a different susceptibility to some compounds such as nikkomycin Z or Congo red, which interfere with cell wall functionality. In addition, the hog1 mutant displayed a colony morphology different from that of the wild-type strain on some media which promote morphological transitions in C. albicans. We show that C. albicans hog1 mutants are derepressed in the serum-induced hyphal formation and, consistently with this behavior, that HOG1 overexpression in Saccharomyces cerevisiae represses the pseudodimorphic transition. Most interestingly, deletion of HOG1 resulted in a drastic increase in the mean survival time of systemically infected mice, supporting a role for this MAP kinase pathway in virulence of pathogenic fungi. This finding has potential implications in antifungal therapy.

Animals↗
PubMed1988

Neomycin inhibits the calcium current of Paramecium.

The duration of high-K+ stimulated backward swimming is a commonly used bioassay for estimating the amplitude of the inward calcium current of Paramecium. Electrophysiological analysis confirmed that concentrations of neomycin which decreased the duration of stimulated backward swimming also reduced the isolated inward calcium current. Other polycations were also effective in this bioassay and their effectiveness was correlated with the number of their positive charges. Paramecium is therefore a convenient model system for studying the effects of compounds such as neomycin on calcium currents as well as their mechanisms of action.

Animals↗
PubMed1984

Lack of correlation between serum angiotensin-converting enzyme activity and bronchoalveolar lymphocytosis in lung sarcoidosis.

Serum angiotensin-converting enzyme activity (SACE) and the number of lymphocytes in bronchoalveolar lavage fluid (BALF) are elevated in many patients with sarcoidosis, and have been proposed as monitors of disease activity. To study the relationship between these two parameters, we have compared SACE values to the percentage of BALF lymphocytes in 23 patients with pulmonary sarcoidosis. Twenty patients had recently diagnosed Stage I or II sarcoidosis and 3 were in Stage III. SACE and BALF lymphocytosis were respectively elevated in 80 and 85% of patients with Stage I and II sarcoidosis, and concordant (i.e. both elevated or both normal) in 75% of these patients. Both SACE and the percentage of BALF lymphocytes were normal in the 3 Stage III patients. No significant correlation was observed between SACE values and the percentage of BALF lymphocytes in our group of 23 patients. Discordance is liable to occur in Stage I patients where increased BALF lymphocytosis and normal SACE may be found, and in smoking patients where elevated SACE may be associated with a normal proportion of BALF lymphocytes.

Adult↗
PubMed1982

Studies of the Ca2+ transport mechanism of human erythrocyte inside-out membrane vesicles. Evidence for the development of a positive interior membrane potential.

Previous observations on the effects of permeant anions on ATP-dependent calcium transport in inside-out vesicles prepared from human erythrocytes suggested that the calcium pump is electrogenic, generating a positive interior membrane potential. The present work demonstrates the development of a positive interior membrane potential across inside-out vesicle membranes during calcium transport in the absence of permeant anions. Several membrane potential probes, 1-anilino-8-naphthalenesulfonate, 3,3'-dipropylthiodicarbocyanine iodide, and an electron paramagnetic resonant triphenylphosphonium derivative, provide qualitative evidence for the development of a membrane potential. Moreover, a number of parallels are observed between the changes in the membrane potential measured by the probes and calcium transport. These include enhancement by calmodulin, time course of change, similar kinetic properties, and the requirement for intact vesicle membranes. Quantitative measurements of the membrane potential shows a positive interior membrane potential of 26-37 mV using radiolabeled permeant anion distribution and 38-57 mV using 3,3'-dipropylthiodicarbocyanine iodide fluorescence changes. These membrane potentials are of a similar magnitude to those reported for the sarcoplasmic reticulum calcium pump (Zimniak, P., and Racker, E. (1978). J. Biol. Chem. 253, 4631-4637).

Anilino Naphthalenesulfonates↗
PubMed1982

Studies on the Ca2+ transport mechanism of human erythrocyte inside-out plasma membrane vesicles. V. Chlortetracycline fluorescence.

The measurement of chlortetracycline fluorescence was employed as a probe for measuring the process to calcium transport by human erythrocyte inside-out vesicles. Chlortetracycline is a divalent metal chelator which increases its fluorescence when bound to calcium in the presence of a membrane. Addition of calcium and ATP to inside out vesicles in the presence of chlortetracycline increased the chlortetracycline fluorescence as a function of time following an initial delay. Only after a threshold level of calcium had been accumulated did the fluorescence increase. The presence of both ATP and calcium were required. The addition of calmodulin increased the rate and absolute magnitude of the chlortetracycline fluorescence change. Similarly, calmodulin stimulated the rate and extent of 45Ca transport by inside-out vesicles. Moreover, the presence of saponin abolished both chlortetracycline fluorescence change and 45Ca uptake; a non-hydrolyzable ATP analog would not substitute for ATP in either 45Ca transport or chlortetracycline fluorescence experiments. Comparison between the slopes of the linear portions of chlortetracycline fluorescence change and calcium transport time courses at varied free calcium concentrations showed a consistent ratio between the slopes. This suggests that calcium transport change can be calibrated by employing chlortetracycline fluorescence. Based on this data, it is concluded that chlortetracycline fluorescence is a rapid and accurate method for monitoring calcium transport by human erythrocyte inside-out vesicles.

Biological Transport, Active↗
PubMed1982

Increased complement-mediated leukocytic histamine release in atopics.

Complement-mediated leukocytic histamine release was compared in normal and atopic subjects using isolated leukocytes or heparinized blood. Leukocytes were treated with zymosan-activated autologous serum, whereas blood was directly incubated with zymosan particles. Histamine released from basophils into the leukocyte supernatant or plasma was measured spectrofluorometrically and expressed in percent of total histamine. In atopics, the mean histamine release (47% for leukocytes and 12% for blood) was significantly higher than in normals (30% and 5%, respectively). Individual variations were large in both groups, and a good concordance was noted between the two techniques. By cross-experiments using activated isologous serum from AB donors instead of autologous serum, it was demonstrated that individual variability was not due to differences in intensity of complement activation. Passive sensitization of normal leukocytes with IgE antibodies increased their ability to release histamine in the presence of activated serum. Thus, high complement-mediated leukocytic histamine release is more commonly found in atopics, and appears to be secondary to an intrinsic abnormality of basophils. It is suggested that complement activation and subsequent inflammation could play, especially in house dust-caused asthma, a more important role than previously appreciated. Moreover, an exaggerated mediator releasability as may occur even in nonatopic subjects, could possibly explain some predisposition to interstitial pulmonary diseases caused by inhalants capable of activating complement.

Adult↗
PubMed1982

[Significance of elevated serum ACE in pneumology].

Angiotensin-converting enzyme (ACE) levels were measured in the serum of patients with various pulmonary affections (sarcoidosis, tuberculosis, anthracosilicosis, cancer, etc.), with diabetes or renal insufficiency, and in 247 healthy subjects. Mean ACE levels (41.5 U/ml +/- 16) were significantly higher in sarcoidosis than in normal controls (22 U/ml +/- 6), high values (greater than or equal to 34 U/ml) being observed in 62 p. cent of cases. In these patients, the ACE tended to become normal in parallel with clinical and radiological improvement in the disease, and to increase again during relapses. In 75 p. cent of sarcoidosis patients there was concordance between the increase in alveolar lymphocytes and that of serum ACE. Elevated ACE levels were noted in only 3 p. cent of non-sarcoidosis pneumopathies, and in 24 and 18 p. cent of diabetes and renal insufficiency cases respectively. In the absence of these two latter affections, measuring ACE levels is of obvious value for the diagnosis and follow-up surveillance of sarcoidosis.

Adult↗
PubMed1981

An in vivo demonstration of the antianaphylactic effect of terbutaline.

Allergen-mediated histamine release was measured on small samples of blood in atopic subjects before and following ingestion of two tablets of terbutaline (5 mg) or placebo. No significant variation of histamine release was observed in the placebo group whereas a statistically significant decrease (maximally 45% of basal value) was found in four of the five patients receiving terbutaline. The mean reduction was about 25% of basal allergen-mediated histamine release. The inhibition was observed 1 hr after taking the drug and persisted for at least 5 hr. Twenty-four hours later the amount of histamine released by antigen was again at its basal value. These data indicate that terbutaline, at what are considered therapeutic doses, has an antianaphylactic action which might be of interest in the treatment of atopic disorders.

Adult↗