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Biomedical subjects

L Anton

Publications and source records attributed to L Anton.

11 recordsLinked to original sources
PubMed2005

Distribution of angiotensin-(1-7) and ACE2 in human placentas of normal and pathological pregnancies.

This work was designed to study the expression of the vasodilator peptide angiotensin-(1-7) [Ang-(1-7)] and its generating enzyme (ACE2) in the uteroplacental interface. Placentas were obtained from 11 early pregnancy failures (5 miscarriages and 6 ectopic pregnancies), 15 normotensive, and 10 preeclamptic gestations. In placental villi, the main sites of immunocytochemical expression of Ang-(1-7) and ACE2 were the syncytiotrophoblast, cytotrophoblast, endothelium and vascular smooth muscle of primary and secondary villi. Syncitial Ang-(1-7) expression in samples obtained from miscarriages and ectopic pregnancies was increased compared to normal term pregnancy [2.0 (2.0-2.25 for the 25 and 75% interquartile range) vs 1.3 (1.0-1.9), p<0.01]. In the maternal stroma, Ang-(1-7) and ACE2 were expressed in the invading and intravascular trophoblast and in decidual cells in all 3 groups. Ang-(1-7) and ACE2 staining was also found in arterial and venous endothelium and smooth muscle of the umbilical cord. The expression of Ang-(1-7) and ACE2 was similar in samples obtained from normal term or preeclamptic pregnancies, except for increased expression of ACE2 in umbilical arterial endothelium in preeclampsia [0.5 (0.5-0.8) vs 0.0 (0.0-0.0), p<0.01]. The uteroplacental location of Ang-(1-7) and ACE2 in pregnancy suggests an autocrine function of Ang-(1-7) in the vasoactive regulation that characterizes placentation and established pregnancy.

Angiotensin I↗
PubMed2004

Enhanced expression of Ang-(1-7) during pregnancy.

Pregnancy is a physiological condition characterized by a progressive increase of the different components of the renin-angiotensin system (RAS). The physiological consequences of the stimulated RAS in normal pregnancy are incompletely understood, and even less understood is the question of how this system may be altered and contribute to the hypertensive disorders of pregnancy. Findings from our group have provided novel insights into how the RAS may contribute to the physiological condition of pregnancy by showing that pregnancy increases the expression of both the vasodilator heptapeptide of the RAS, angiotensin-(1-7) [Ang-(1-7)], and of a newly cloned angiotensin converting enzyme (ACE) homolog, ACE2, that shows high catalytic efficiency for Ang II metabolism to Ang-(1-7). The discovery of ACE2 adds a new dimension to the complexity of the RAS by providing a new arm that may counter-regulate the activity of the vasoconstrictor component, while amplifying the vasodilator component. The studies reviewed in this article demonstrate that Ang-(1-7) increases in plasma and urine of normal pregnant women. In preeclamptic subjects we showed that plasma Ang-(1-7) was suppressed as compared to the levels found in normal pregnancy. In addition, kidney and urinary levels of Ang-(1-7) were increased in pregnant rats coinciding with the enhanced detection and expression of ACE2. These findings support the concept that in normal pregnancy enhanced ACE2 may counteract the elevation in tissue and circulating Ang II by increasing the rate of conversion to Ang-(1-7). These findings provide a basis for the physiological role of Ang-(1-7) and ACE2 during pregnancy.

Angiotensin I↗
PubMed2002

Noncollapsing solution below r(c) for a randomly forced particle.

We show that a noncollapsing solution below r(c) can be constructed for the dynamics of randomly forced particle interacting with a dissipating boundary. The scaling analysis predicts a divergent collision rate at the boundary for the noncollapsing solution. This prediction is tested numerically.

Journal Article↗
PubMed2001

Time-Inhomogeneous Fokker-Planck Equation for Wave Distributions in the Abelian Sandpile Model.

The time and size distributions of the waves of topplings in the Abelian sandpile model are expressed as the first arrival at the origin distribution for a scale invariant, time-inhomogeneous Fokker-Plank equation. Assuming a linear conjecture for the time inhomogeneity exponent as a function of a loop-erased random walk (LERW) critical exponent, suggested by numerical results, this approach allows one to estimate the lower critical dimension of the model and the exact value of the critical exponent for LERW in three dimensions. The avalanche size distribution in two dimensions is found to be the difference between two closed power laws.

Journal Article↗
PubMed2001

Impact of nonpenetrating clips on intimal hyperplasia of vascular anastomoses.

Non-penetrating, arcuate-legged titanium clips create an interrupted, non-penetrated, yet compliant vascular anastomoses that is associated with significantly reduced anastomotic neointimal hyperplasia. Recent experimental and clinical studies provide evidence that the non-suture alternative changes the biology of vessel-to-vessel and graft-to-vessel connections that reduces the stimulus for hyperplasia at a number of critical points in the response to injury schema. The compliant, "blood-tight" characteristics of clipped vascular reconstructions are associated with no endothelial injury or intraluminal foreign body, minimal platelet aggregation and laminal flow. Clinical applications including vascular access, femoropopliteal bypass, and closure of carotid endarterectomies are remarkable for the absence of restenosis and preserved anastomotic patency.

Anastomosis, Surgical↗
PubMed1999

Trapping and mobilization of residual fluid during capillary desaturation in porous media.

We discuss the problem of trapping and mobilization of nonwetting fluids during immiscible two-phase displacement processes in porous media. Capillary desaturation curves give residual saturations as a function of capillary number. Interpreting capillary numbers as the ratio of viscous to capillary forces the breakpoint in experimental curves contradicts the theoretically predicted force balance. We show that replotting the data against a novel macroscopic capillary number resolves the problem for discontinuous mode displacement.

Journal Article↗
PubMed1999

Simple equation for earthquake distribution.

The earthquake distribution, the Gutenberg-Richter law, is obtained postulating a connection through a diffusion process between the kinetic energy of the active zone and the radiated energy. A link between the value of the critical exponent and the stress release is proposed.

Journal Article↗
PubMed1998

[Outcome of combined trabeculectomy with cataract operation and intraocular lens implantation].

BACKGROUND: When trabeculectomy and cataract extraction with intraocular lens insertion are combined, do the success and complication rates add. MATERIAL AND METHODS: Follow-up of 47 eyes of 34 patients with combined trabeculectomy and cataract extraction with intraocular lens implantation after 12 to 42 months. RESULTS: With a low perioperative complication rate the intraocular pressure after one year was below 22 mm Hg in 90% without any medication and in 98% additional glaucoma therapy. After 2 and 3 years the intraocular pressure was normal without any additional therapy in 83% of the eyes. The visual acuity was better or equal to the preoperative value in 89% of the cases. CONCLUSIONS: The combination of trabeculectomy and of cataract extraction with intraocular lens implantation has a low complication rate and gives good results regarding intraocular pressure and visual rehabilitation. When a trabeculectomy is indicated, the indication for a simultaneous cataract extraction with intraocular lens implantation should not be to restricted.

Aged↗
PubMed1978

cis-Platinum ototoxicity.

The incidence and spectrum of ototoxicity secondary to cis-platinum administration in 104 cancer patients ranging in age from 8-78 years were determined. Pure tone thresholds from 500 to 8000 Hz were evaluated prior to and following cis-platinum administration. The most sensitive frequencies were 6000 and 8000 Hz. Younger patients had lower threshold increases per administered dose than older patients. High drug dosages caused larger threshold elevations and extended to lower frequencies. Prehydration and mannitol infusion did not alter ototoxicity. Audiographic evaluation appears necessary for monitoring the treatment of cancer patients with cis-platinum.

Adolescent↗