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F Proverbio

Publications and source records attributed to F Proverbio.

At least 19 recordsLinked to original sources
PubMed2003

Chlamydia trachomatis and sperm lipid peroxidation in infertile men.

AIM: To relate the presence of anti-Chlamydial trachomatis IgA in semen with sperm lipid membrane peroxidation and changes in seminal parameters. METHODS: Semen samples of the male partners of 52 couples assessed for undiagnosed infertility were examined for the presence of IgA antibody against C. trachomatis. The level of sperm membrane lipid peroxidation was estimated by determining the malondialdehyde (MDA) formation. RESULTS: Sperm membrane of infertile males with positive IgA antibodies against C. trachomatis showed a higher level of lipid peroxidation than that of infertile males with negative IgA antibody (P<0.05). There was a positive correlation (P<0.01) between the level of C. trachomatis antibody and the magnitude of sperm membrane lipid peroxidation. All the other tested semen parameters were found to be similar in the two groups. CONCLUSION: The activation of immune system by C. trachomatis may promote lipid peroxidation of the sperm membrane. This could be the way by which C. trachomatis affects fertility.

Chlamydia Infections↗
PubMed2001

Bioactivity of serum hCG in preeclampsia.

OBJECTIVE: To compare hCG levels, obtained by biologic and immunologic means, in women with normal pregnancies and women with preeclampsia. METHODS: Peripheral blood samples from women in the third trimester with preeclampsia (n = 30) or normal pregnancies (n = 30) were assayed for immunoactive and bioactive hCG (mouse Leydig cell testosterone production assay). RESULTS: Serum bioactive hCG levels tended to be lower than normal, and immunoactive hCG levels tended to be higher in women with preeclampsia, but the differences were not statistically significant. However, the ratio of bioactive to immunoactive hCG was significantly lower than normal for preeclamptic women (0.70 +/- 0.28 vs. 1.15 +/- 0.35 for normotensive pregnant women [mean +/- standard deviation], P <.001). CONCLUSION: The ratio of bioactive to immunoreactive serum hCG is lower among preeclamptic than among normotensive pregnant women.

Biological Assay↗
PubMed2001

Preeclampsia and Na,K-ATPase activity of red blood cell ghosts from neonatal and maternal blood.

We determined Na,K-ATPase activity and cholesterol/phospholipid ratio of maternal and cord red blood cell ghosts from either normotensive or preeclamptic pregnant women. The Na,K-ATPase activity of the red cell ghosts from neonatal blood is significantly lower (25-32%) as compared with the ATPase activity of the maternal red cell ghosts, regardless of the presence or not of preeclampsia. This diminution in Na,K-ATPase activity of the neonatal red blood cell ghosts could be due to an increase in the cholesterol/phospholipid molar ratio of the membrane. The Na,K-ATPase activity of the red blood cell ghosts from pregnant women was unaffected by preeclampsia; however, fetal red blood cell ghosts from infants of preeclamptic mothers showed a significantly lower ATPase activity (20%) than fetal red blood cell ghosts from infants of normotensive mothers. A low Na,K-ATPase activity in the neonatal red blood cells from mothers with preeclampsia could be an indication of an important modification of the physiological role of this enzyme.

Cholesterol↗
PubMed2001

Comparative study of the calcium adenosine triphosphatase of basal membranes of human placental trophoblasts from normotensive and preeclamptic pregnant women.

The Ca-ATPase activity of plasma membranes from human trophoblast is diminished in about 50% in preeclamptic women, as compared to normotensive pregnant women. This diminution is not due to changes in the behavior of the enzyme towards the free calcium concentration, the pH or the temperature of the incubation medium. Neither does it appear to be due to the presence of some condensing factor in the membranes, since the apparent energies of activation for the two tested ranges of temperature (10-20 and 20-37 degrees C) are similar for both normotensive and preeclamptic patients. The possibility of a diminution in the turnover rate of the Ca-ATPase in the plasma membranes from the preeclamptic patients is considered.

Adult↗
PubMed2000

Ca-ATPase of human syncytiotrophoblast basal plasma membranes.

In the present work, a Mg(2+)-dependent, Ca(2+)-stimulated ATPase activity was determined and characterized in purified preparations of syncytiotrophoblast basal (fetal facing) plasma membranes, and its characteristics were compared to those of the active Ca(2+)-transport already demonstrated in this tissue. Similar to the active Ca(2+)transport, the Ca-ATPase is Mg(2+)-dependent, is stimulated by calmodulin, and is inhibited by vanadate. The K(m) for Ca(2+)activation is 0.25+/- 0.02microM, a value near to that described for calcium active transport in this tissue. Consequently, the Ca-ATPase activity of human syncytiotrophoblast basal plasma membrane described in this paper could be responsible for the active extrusion of calcium from the syncytiotrophoblast toward the fetal circulation.

5'-Nucleotidase↗
PubMed2000

Ca-ATPase of human myometrium plasma membranes.

We determined and characterized the Mg2+-dependent, Ca2+-stimulated ATPase (Ca-ATPase) activity in cell plasma membranes from the myometrium of pregnant women, and compared these characteristics to those of the active Ca2+-transport already demonstrated in this tissue. Similarly to the Ca2+-transport system, the Ca2+-ATPase is Mg2+-dependent, stimulated by calmodulin, and inhibited by vanadate. The Km for Ca2+ activation is 0.40 microM, very similar to that found for active calcium transport, i.e. 0.25 microM. Consequently, this Ca2+-ATPase can be responsible for the active calcium transport across the plasma membranes of smooth muscle cells.

5'-Nucleotidase↗
PubMed1998

Preeclampsia, lipid peroxidation, and calcium adenosine triphosphatase activity of red blood cell ghosts.

OBJECTIVE: We evaluated the effect of lipid peroxidation on the calcium adenosine triphosphatase activity of red blood cell ghosts from normotensive pregnant women and compared it with the adenosine triphosphatase activity and lipid peroxidation in preeclampsia. STUDY DESIGN: Ten nulliparous normotensive and 10 nulliparous preeclamptic pregnant women (38 to 39 weeks of gestation) were used as blood donors. Preeclampsia was diagnosed on the basis of blood pressure (>140/90 mm Hg) and proteinuria (>0.5 gm of urinary protein per day). Red blood cell ghosts were prepared for both groups and used for calcium adenosine triphosphatase activity and lipid peroxidation determinations. Control ghosts (normotensive) were irradiated with ultraviolet light for different lengths of time. RESULTS: Calcium adenosine triphosphatase activity of red blood cell ghosts from normotensive women is sensitive to lipid peroxidation. The lipid peroxidation of red blood cell ghosts from preeclamptic women is higher than that from normotensive women. CONCLUSION: The diminution of the calcium adenosine triphosphatase activity with preeclampsia could be explained by the sensitivity of this adenosine triphosphatase to lipid peroxidation.

Adult↗
PubMed1998

Ouabain-insensitive Na(+)-ATPase activity of Malpighian tubules from Rhodnius prolixus.

In the present paper, we show the existence of a furosemide-sensitive Na(+)-stimulated, Mg(2+)-dependent ATPase activity in cell lysates of Malpighian tubular cells from Rhodnius prolixus, which could be the biochemical expression of the Na(+)-pump. The main characteristics of this activity are: (1) K0.5 for Na+ = 1.49 +/- 0.18 mM, (2) Vmax = 2.8 +/- 0.1 nmol inorganic orthophosphate (Pi).mg prot-1.min-1, (3) it is fully abolished by 2 mM furosemide, (4)it is insensitive to ouabain concentrations up to 10(-2) M, (5) it is sensitive to the presence of vanadate in the incubation medium indicating it to be a P-type ATPase, and (6) it is stimulated by nanomolar concentrations of Ca2+ in the incubation medium.

Adenosine Triphosphatases↗
PubMed1996

Inhibitory effect of ethanol on the Na(+)-ATPase activity of rat kidney proximal tubular cell plasma membranes.

The inhibitory effect of 2% ethanol (400 mM) in the incubation medium on several characteristics of the Na(+)-ATPase of basolateral plasma membranes from rat kidney proximal tubular cells was investigated. Ethanol did not change the Km of the enzyme for Mg2+, ATP or Na+; it did not change either the optimal pH or temperature values of the incubation medium for the enzyme to act and finally, it did not affect the apparent energy of activation of the enzyme. It was also found that 2% ethanol produced stronger inhibition of the ATPase when it is in an activated or stimulated state, than when it is working at its lower basal level. The presented results can be explained by assuming that 2% ethanol in the incubation medium inhibits Na(+)-ATPase activity by affecting the enzyme structure as well as its activating mechanism.

Adenosine Triphosphatases↗
PubMed1995

Na,K-ATPase activity in red blood cells from patients with Chediak-Higashi syndrome.

Na,K-ATPase activity of red blood cells from Chediak-Higashi syndrome (CHS) patients and relatives (gene heterozygous) was determined and compared to that of control, healthy, individuals. The enzyme activity was found to be strongly diminished in the CHS patients and slightly lower in their relatives. This reduced activity was due to a lower turnover number of the Na, K-ATPase as well as a decreased number of pumps. The reduced enzyme activity observed in these patients could be the result of an abnormal cell membrane fluidity, and the lowered number of Na, K-pumps could be explained as a consequence of an altered or deficient cell machinery caused by the CHS gene.

Adolescent↗
PubMed1995

Ouabain-insensitive, Na(+)-stimulated ATPase activity in rabbit cardiac sarcolemma.

The rabbit cardiac sarcolemma shows an ouabain, Na,K-stimulated ATPase activity and an ouabain-insensitive, Na-stimulated ATPase activity. The Na-ATPase has the following characteristics: (i) It is also stimulated by other monovalent cations. (ii) It is inhibited by 2 mM Furosemide and by 2 mM ethacrynic acid. (iii) It reaches maximal values (Vmax) at around 20 mM Na+. (iv) The apparent Km is around 5 mM. Except for the monovalent cation stimulation, the main characteristics of this ATPase are very similar to those of the ouabain-insensitive, Na-stimulated ATPase of mammalian kidneys.

Adenosine Triphosphatases↗
PubMed1994

Preeclampsia and calcium adenosine triphosphatase activity of red blood cell ghosts.

OBJECTIVE: The current work was undertaken to study the calcium adenosine triphosphatase activity of red blood cell membranes from pregnant women with preeclampsia. STUDY DESIGN: Six normotensive and six preeclamptic pregnant women at 38 to 39 weeks of gestation were studied. The diagnosis of preeclampsia was made on the basis of blood pressure (> 140/90 mm Hg), proteinuria (> 0.5 gm of urinary protein per day), or edema. Hemoglobin-free red blood cell ghosts were prepared from the heparinized blood samples and were used to determine the calcium adenosine triphosphatase activity. RESULTS: It was found that the calcium adenosine triphosphatase activity of preeclamptic women is diminished by about 50% compared with that of normotensive pregnant women. CONCLUSION: A diminution of the calcium adenosine triphosphatase activity of erythrocytes in preeclampsia might be an indication that the in vivo activity of the calcium pump of these cells is diminished, which could, in turn, drive the cells to increase their cytoplasmic free calcium concentration.

Adult↗
PubMed1994

Studies on the effect of ethanol on the Na+, and the Na+, K(+)-ATPase activities of plasma membranes of rat kidney proximal tubular cells.

In the present work it was investigated the effect of 2% ethanol on the Na+ and on the Na+, K(+)-ATPase activities. The differential effect of the alcohol on the two ATPases (approximately 40% inhibition of the Na(+)-ATPase and approximately 10% inhibition of the Na+, K(+)-ATPase), is not due to a higher degree of denaturalization of the enzyme, nor to a faster effect of ethanol on the Na(+)-than on the Na+, K(+)-ATPase. Our results show that ethanol affects the selectivity of the Na+, K(+)-ATPase for Na+ and/or for K+, enhancing the Na+ affinity for the K+ sites, and/or reducing the K+ affinity for its own sites. This effect was not seen for the Na(+)-ATPase, indicating that 2% ethanol inhibits the two ATPases in a totally different way.

Animals↗
PubMed1993

[Modulation of Na pump in proximal kidney tubules cells of the rat].

The present paper shows evidence indicating that one of the active mechanisms of sodium extrusion shown to be present in basolateral plasma membranes of the proximal tubular cells of mammalian kidney, the Na-pump (which extrudes sodium from the cells accompanied by chloride and water), is modulated in its activity by the cell volume. An increase of the cell volume, produces a concomitant increase of the activity of the Na-pump. On the other hand, the activity of the Na, K-pump, which extrudes sodium from the cells in exchange for potassium, is totally independent of the cell volume. The modulating effect of the cell volume on the activity of the Na-pump, can be either demonstrated under "in vitro" or "in vivo" conditions.

Animals↗
PubMed1992

Effect of ethanol on the Na(+)- and the Na+,K(+)-ATPase activities of basolateral plasma membranes of kidney proximal tubular cells.

The Na(+)- and the Na+,K(+)-ATPase activities of basolateral plasma membranes from rat kidney proximal tubular cells were affected differentially by ethanol. Moreover, at concentrations of ethanol that can be reached in vivo in the blood plasma (50 mM) there was a significant effect on the Na(+)-ATPase activity and practically no effect on the Na+,K(+)-ATPase activity.

Adenosine Triphosphatases↗
PubMed1991

Ouabain-insensitive Na-ATPase activity in homogenates from different animal tissues.

1. Two Na(+)-stimulated ATPase activities were determined in gill homogenates from squid, shrimp and teleost fish; in kidney slice homogenates from teleost fish, bullfrog, toad, iguana, chicken, duck, rat, pig and cow, as well as in homogenates from rat small intestinal cells, brain cortex and liver slices. The two Na(+)-stimulated ATPase activities, the Na- and the Na,K-ATPase, showed a different behavior toward K+ and ouabain. 2. The ouabain-insensitive, K(+)-independent, Na-ATPase activity for all the studied homogenates was completely inhibited by 2 mM furosemide. 3. An increase in cell volume of the kidney, brain cortex and liver slice preparations, as well as of the rat small intestinal cells, produced a concomitant increase of the ouabain-insensitive Na-ATPase.

Adenosine Triphosphatases↗