Biomedical subjects

Marta Rodríguez

Publications and source records attributed to Marta Rodríguez.

13 recordsLinked to original sources

PubMed2006

[Chronotherapy with torasemide in hypertensive patients: increased efficacy and therapeutic coverage with bedtime administration].

BACKGROUND AND OBJECTIVE: Torasemide is a high ceiling loop diuretic frequently used for treatment of heart failure, renal failure and hypertension, according to results mainly based on clinic blood pressure measurements, without proper evaluation of the 24-hour efficacy of the drug. Accordingly, we investigated the time-dependent antihypertensive efficacy of torasemide in hypertensive patients. PATIENTS AND METHOD: We studied 58 patients with grade 1-2 essential hypertension (25 men and 33 women), 48.7 (11.9) years of age, randomly assigned to receive torasemide (5 mg/day) either upon awakening or at bedtime. Blood pressure was measured by ambulatory monitoring for 48 consecutive hours before and after 6 weeks of therapy. RESULTS: Efficacy of torasemide was significantly higher with bedtime dosing (11.2 and 8.0 mmHg reduction in the 24-hour mean of systolic and diastolic blood pressure, respectively) as compared to the administration of the drug on awakening (6.2 and 3.7 mmHg reduction in systolic and diastolic blood pressure). The percentage of patients with controlled ambulatory blood pressure after treatment was also higher after bedtime treatment (54% versus 27%). The time-response curves indicate a full 24-hour therapeutic duration only when torasemide was administered before bedtime. With regard to the safety profile, 2 patients presented secondary effects (abdominal pain, diarrhea) in morning dose, and 4 patients taking the drug at bedtime reported nicturia. CONCLUSIONS: A dose of 5 mg/day torasemide is effective for blood pressure reduction after bedtime administration. The differences in efficacy and therapeutic duration as a function of the circadian time of treatment with torasemide here documented should be taken into account when prescribing this loop diuretic for treatment of patients with essential hypertension.

Blood Pressure↗

PubMed2006

Midline abdominal wall closure: a new prophylactic mesh concept.

BACKGROUND: Despite intense research efforts, incisional hernias continue to be a problem in patients who undergo laparotomy. This study was designed to reinforce the midline laparotomy closure by including a new prosthetic design between the edges of the surgical wound. STUDY DESIGN: A midline incision was made in New Zealand white rabbits and closed by inserting a polypropylene strip, T-shaped in cross-section, between the incisional borders. The T was placed upside down such that the horizontal arm of the T, whose surface is coated with extra-low pore size expanded polytetrafluoroethylene, made contact with the visceral peritoneum. The mesh was secured by a mass polypropylene 3/0 running suture. Surgery outcomes in these animals were compared with those in which the surgical wound was closed by simple suture and with control, nonoperated animals. RESULTS: The T-mesh induced an increased amount of scar tissue at the midline, where neoformed recipient tissue appeared around the polypropylene mesh filaments. The expanded polytetrafluoroethylene lamina became appropriately mesothelialized. Compared with the simple suture, the T-mesh provided a significant gain in biomechanical strength at postoperative week 6 (43.99+/-4.17 Newtons and 56.96+/-10.94 Newtons, respectively, p < 0.05). At 6 months, the strength of the reinforced wound even surpassed, although not significantly, that of the control intact abdominal wall (82.25+/-7.60 Newtons versus 79.55+/-11.46 Newtons). Data were expressed as mean +/- standard deviation. CONCLUSIONS: The use of a nonabsorbable biomaterial for midline laparotomy closure significantly improves its biomechanical resistance. Used in high-risk patients or even prophylactically, this technique could reduce the incidence of incisional hernia.

Abdominal Wall↗

PubMed2005

Differing administration time-dependent effects of aspirin on blood pressure in dipper and non-dipper hypertensives.

Aspirin is a potent antioxidative agent that reduces vascular production of superoxide, prevents angiotensin II-induced hypertension, and induces NO release. Low-dose aspirin administered at bedtime, but not on awakening, has also been shown to reduce blood pressure, possibly enhancing the nocturnal trough in NO production. Because endothelium-dependent vasodilation is blunted through a decrease in NO release in non-dipper compared with dipper patients, we compared the administration time-dependent influence of aspirin on ambulatory blood pressure in dipper and non-dipper hypertensive subjects. We studied 257 patients with mild hypertension (98 men and 159 women), 44.6+/-12.5 years of age, randomly assigned to receive 100 mg per day of aspirin either on awakening or at bedtime. Ambulatory blood pressure was measured for 48 hours at baseline and after 3 months of intervention. Blood pressure was slightly elevated after aspirin on awakening (increase of 1.5/1.0 mm Hg in the 24-hour mean of systolic/diastolic blood pressure; P<0.028). A highly significant blood pressure reduction was observed in patients who received aspirin at bedtime (decrease of 7.2/4.9 mm Hg in systolic/diastolic blood pressure; P<0.001). The reduction in nocturnal blood pressure mean was double in non-dippers (11.0/7.1 mm Hg) compared with dippers (5.5/3.3 mm Hg; P<0.001). This prospective trial corroborates the significant administration time-dependent effect of low-dose aspirin on blood pressure, mainly in non-dipper hypertensive patients. The timed administration of low-dose aspirin could thus provide a valuable approach, beyond prevention of cardiovascular disease, in the blood pressure control of patients with mild hypertension.

Adult↗

PubMed2005

[Composite prostheses for the repair of abdominal wall defects: comparative study of physical and/or chemical barriers].

INTRODUCTION: Composite biomaterials designed for the repair of abdominal wall defects are usually composed of a reticular component and a second component, or barrier, which is laminar (absorbable or non-reabsorbable) and which is placed in contact with the visceral peritoneum. This study was designed to evaluate how the composition of this second component affects the biological behavior of the biomaterial and the formation of adhesions. MATERIAL AND METHODS: Defects (7 x 5 cm) comprising all the tissue planes except the skin were created in the anterior abdominal wall of white, New Zealand rabbits. In group A (n = 12) the defects were then repaired with composite prostheses with a non-reabsorbable physical barrier, polypropylene + ePTFE (PL + ePTFE) and PL + polyurethane (PL + PU). In group B (n = 12) the defects were repaired with a reabsorbable chemical barrier, polyester + a polyethyleneglycol/glycerol film (PO + gl) and PL + hyaluronate (PL + hy). Fourteen days after surgery, the animals were sacrificed and specimens were taken for light and scanning electron microscopy and immunohistochemical labeling for macrophages (RAM-11). Adhesions forming at the prostheses/visceral peritoneum interface were quantified. RESULTS: All the materials showed optimal tissue infiltration and mesothelialization. Adhesion formation was similar in prostheses with a physical barrier (PL + ePTFE, 0.49 +/- 0.14%; PL-PU, 0.29 +/- 0.2%). In contrast, those with a chemical barrier showed a significant difference in adhesion formation (PO + gl, 0.55 +/- 0.06%; PL + hy, 18.55 +/- 4.96%; p < 0.05). CONCLUSIONS: Physical barriers seem to induce similar adhesions, while adhesions formed to prostheses with chemical barriers can vary considerably, possibly depending on the chemical composition of the barrier.

Animals↗

PubMed2005

[Polypropylene and polydioxanone show similar biomechanical efficacy in midline closure].

INTRODUCTION: After laparotomy, the incidence of incisional hernia is high, especially when the abdomen in opened along the linea alba, a weak structure of the abdominal wall. This study was designed to evaluate the biomechanical resistance of midline closure using the same surgical technique but two different types of suture material, a long-lasting absorbable material and a non-absorbable material. MATERIAL AND METHODS: A 7.5 cm midline laparotomy was performed in 48 New Zealand White rabbits. The surgical wound was then repaired with an en masse running suture using polypropylene 4/0 or polydioxanone 4/0. Animals not subjected to surgery were used as controls. Morphological, immunohistochemical and biomechanical tests were undertaken 3 weeks, 6 weeks and 6 months after surgery. RESULTS: Both types of suture gave rise to scar tissue composed of collagen fibers concentrically arranged around the suture filaments. Six months after surgery, the polydioxanone suture had almost completely degraded. The macrophage response steadily diminished over time, although it was significantly greater in wounds closed by polydioxanone suture. No significant differences were found in the biomechanical strength provided by the two types of suture. CONCLUSIONS: After laparotomy closure at the linea alba, both suture materials showed optimal biological behavior. The composition of the suture material did not affect the tensile strength of the repair zone.

Animals↗

PubMed2005

Administration time-dependent effects of valsartan on ambulatory blood pressure in elderly hypertensive subjects.

Previous results have indicated that valsartan administration at bed-time, as opposed to upon wakening, improves the diurnal/nocturnal ratio of blood pressure (BP) toward a normal dipping pattern, without loss of 24 h efficacy. This ratio is characterized by a progressive decrease with aging. Accordingly, we investigated the administration time-dependent antihypertensive efficacy of valsartan, an angiotensin blocking agent, in elderly hypertensive patients. We studied 100 elderly patients with grade 1-2 essential hypertension (34 men and 66 women), 68.2+/-4.9 years of age, randomly assigned to receive valsartan (160 mg/d) as a monotherapy either upon awakening or at bed-time. BP was measured for 48 h by ambulatory monitoring, at 20 min intervals between 07:00 to 23:00 h and at 30 min intervals at night, before and after 3 months of therapy. Physical activity was simultaneously monitored every minute by wrist actigraphy to accurately determine the duration of sleep and wake spans to enable the accurate calculation of the diurnal and nocturnal means of BP for each subject. There was a highly significant BP reduction after 3 months of valsartan treatment (p < 0.001). The reduction was slightly larger with bed-time dosing (15.3 and 9.2 mm Hg reduction in the 24 h mean of systolic and diastolic BP, respectively) than with morning dosing (12.3 and 6.3 mm Hg reduction in the 24 h mean of systolic and diastolic BP, respectively). The diurnal/nocturnal ratio, measured as the nocturnal decline of BP relative to the diurnal mean, was unchanged in the group ingesting valsartan upon awakening (-1.0 and -0.3 for systolic and diastolic BP; p > 0.195). This ratio was significantly increased (6.6 and 5.4 for systolic and diastolic BP; p < 0.001) when valsartan was ingested at bed-time. The reduction of the nocturnal mean was doubled in the group ingesting valsartan at bed-time, as compared to the group ingesting it in the morning (p < 0.001). In elderly hypertensive patients, mainly characterized by a diminished nocturnal decline in BP, bed-time valsartan dosing is better than morning dosing since it improves efficacy during the nighttime sleep span, with the potential reduction in cardiovascular risk that has been associated with a normalized diurnal/nocturnal BP ratio.

Antihypertensive Agents↗

PubMed2004

Improved biomechanical resistance using an expanded polytetrafluoroethylene composite-structure prosthesis.

We designed a composite-structure (laminar-reticular) prosthesis using expanded polytetrafluoroethylene (ePTFE) as the biomaterial in an attempt to improve the biomechanical resistance of the same biomaterial in the form of a single lamina. Defects (7 x 5 cm) were created in the abdominal wall of male white New Zealand rabbits (n = 24). The defects, which comprised all the wall layers except the skin, were then repaired with one of two types of ePTFE prosthesis. One was a latest generation laminar prosthesis (DualMesh, or Gore-Tex) and the other was a composite of in-house design (CV-4 mesh composite) made by suturing a mesh woven out of ePTFE thread to an ePTFE lamina. After sacrificing the animals at 14 or 90 days after surgery, implant specimens were subjected to morphologic analysis (light microscopy and scanning electron microscopy); and adhesion formation, neoperitoneal thickness, and biomechanical strength were evaluated. No significant differences were recorded between the two prosthesis regarding the consistency of adhesions or the area occupied by adhesions (DM 0.17 +/- 0.06; CV-4 mesh composite 0.18 +/- 0.08 cm2) (p > 0.05). Notably, improved tissue integration was achieved using the composite prosthesis; its reticular side became infiltrated by dense connective tissue that enveloped the mesh filaments. In contrast, the DM prosthesis became encapsulated by host tissue. The neoperitoneum induced by both prostheses was homogeneous and orderly, with a layer of typical mesothelial cells lining its inner surface. The thickness of the neoperitoneum was similar (p > 0.05) for the two implants (385.0 +/- 3.4 vs. 390 +/- 3.1 microm), although significantly higher (p < 0.05) mechanical resistance values were recorded for the composite prosthesis (26.75 +/- 3.71 vs. 14.11 +/- 3.71 N). Our findings suggest that the use of a reticular and a laminar ePTFE layer in the same prosthesis leads to better repair and biomechanical behavior compared to the use of a single-structure laminar implant.

Abdominal Wall↗

PubMed2004

Temporary closure of the abdomen using a new composite prosthesis (PL-PU99).

BACKGROUND: Temporary abdominal wound closure is sometimes desirable when tension-free approximation of the wound edges is impractical or when reexploration is planned. METHODS: The behavior of a composite prosthesis (PL-PU99) designed by our group was evaluated as a method of temporary abdominal closure in white New Zealand rabbits. After a 7 cm long midline laparotomy, a spindle-shaped 4 cm (maximum width) by 7 cm (length) fragment of PL-PU99 was sutured to the edges of the peritoneal, muscular, and fascial abdominal tissues, so that the biomaterial remained in contact with the exterior. The PL-PU99 composite is composed of a polypropylene mesh adhered to a sheet of polyurethane with an acrylic cement. At 7 and 14 days after implant, animals were sacrificed and specimens taken for morphological, ultrastructural, morphometry of the neoperitoneum, and immunohistochemical (macrophage reaction, RAM-11) analysis. RESULTS: No death or signs of infection or rejection of the prostheses were recorded. No adhesions could be macroscopically observed between the composite and the intestinal loops. The biomaterial achieved a good seal, no leakage of fluids being detected. Fourteen days after implant, the neoperitoneum formed on the prosthesis was of an even structure and was made up of organized, vascularized connective tissue covered by an uninterrupted mesothelium. CONCLUSIONS: The PL-PU99 prosthesis shows optimal behavior at the prosthesis/visceral peritoneum interface, making it ideal for its use in the temporary closure of the abdomen. The implanted composite may also prove useful for the permanent repair of the abdominal wall.

Abdominal Wall↗

PubMed2004

New approach to improving endothelial preservation in cryopreserved arterial substitutes.

The endothelial loss provoked by the methods of vascular cryopreservation used at most human vessel banks is one of the main factors leading to the failure of grafting procedures performed using cryopreserved vessel substitutes. This study evaluates the effects of the storage temperature and thawing protocol on the endothelial cell loss suffered by cryopreserved vessels, and optimises the thawing temperature and protocol for cryopreserving arterial grafts in terms of that producing least endothelial loss. Segments of the common iliac artery of the minipig (n = 20) were frozen at a temperature reduction rate of 1 degrees C/min in a biological freezer. After storing the arterial fragments for 30 days, study groups were established according to the storage temperature (-80, -145 or -196 degrees C) and subsequent thawing procedure (slow or rapid thawing). Fresh vessel segments served as the control group. Once thawed, the specimens were examined by light, transmission, and scanning electron microscopy. The covered endothelial surface was determined by image analysis. Data for the different groups were compared by one way ANOVA. When cryopreservation at each of the storage temperatures was followed by slow thawing, the endothelial cells showed improved morphological features and viability over those of specimens subjected to rapid thawing. Rapidly thawed endothelial cells showed irreversible ultrastructural damage such as mitochondrial dilation and rupture, reticular fragmentation, and peripheral nuclear condensation. In contrast, slow thawing gave rise to changes compatible with reversible damage in a large proportion of the endothelial cells: general swelling, reticular dilation, mitochondrial swelling, and nuclear chromatin condensation. Gradually thawed cryopreserved arteries showed a lower proportion of damaged cells identified by the TUNEL method compared to the corresponding rapidly thawed specimens (p < 0.05, for all temperatures). In all the groups in which vessels underwent rapid thawing (except at -145 degrees C), significant differences (p < 0.05) in endothelial cover values were recorded with respect to control groups. Storage of cryopreserved vessels at -80 degrees C followed by rapid thawing led to greatest endothelial cell loss (61.36+/-9.06% covered endothelial surface), while a temperature of -145 degrees C followed by slow thawing was best at preserving the endothelium of the vessel wall (89.38+/-16.67% surface cover). In conclusion, storage at a temperature of -145 degrees C in nitrogen vapour followed by gradual automated thawing seems to be the best way of preserving the endothelial surface of the arterial cryograft. This method gives rise to best endothelial cell viability and cover values, with obvious benefits for subsequent grafting.

Animals↗

PubMed2004

Restoring the endothelium of cryopreserved arterial grafts: co-culture of venous and arterial endothelial cells.

The use of arterial homografts in clinical practice is becoming increasingly common, yet there is an urgent need to address one of the most well-established problems associated with their use: the loss of integrity of the endothelium following cryopreservation. The partial lack of endothelium causes contact between the extracellular matrix and blood flow, which, in turn, often gives rise to thrombosis and/or restenosis. Our objective was first to attempt to replace the arterial endothelial cells lost during the cryopreservation process by seeding autologous venous endothelial cells, and to evaluate the behaviour of venous and arterial endothelial cells in co-culture. The idea was to establish whether venous endothelial cells would be accepted by arterial endothelial cells and could therefore be used to restore the endothelial lining for the subsequent use of these vessels in in vivo grafting procedures. For the co-culture experiments, endothelial cells were obtained from the jugular vein and both iliac arteries of the minipig by treatment with 0.1% type I collagenase. The venous endothelial cells were fluorescently labelled with the membrane intercalating dye PKH26. Equal numbers of venous and arterial endothelial cells were mixed and co-cultured for 24h, 48h or 4 days. Cell viability, determined by 2% trypan blue staining and the TUNEL method, was established before and after fluorescence labelling. Cellular activity was determined by estimating PGI2 levels in the cultures. The proliferation index was established by [H(3)]thymidine (1muCi/ml) in the cell culture medium. For the in vivo tests, 5 cm length segments of minipig iliac artery were used to establish the groups: control (n = 6), fresh arterial segments; group I (n = 16), cryopreserved arterial segments and group II (n = 16), cryopreserved arterial segments seeded with autologous venous endothelial cells. The cryopreserved vessels in group II were seeded by flooding with a labelled venous endothelial cell suspension. Once seeded, the arterial segments were included in an in vitro flow circuit. All the specimens were processed for fluorescence and light microscopy, and scanning electron microscopy. The denuded endothelial surface was determined in each group. Cell death was evaluated by the TUNEL method. We confirmed the existence of intercellular PECAM1-type junctions between venous (PKH26+) and arterial cells in co-culture and the functional activity of the cells. The cryopreserved arterial segments showed a well-preserved wall structure. However, different size areas of marked endothelial denudation were detected. After seeding with labelled cells (PKH26+), these denuded areas of the cryopreserved artery were entirely covered by fluorescent cells. After seeding, a drop in the proportion of damaged endothelial cells was recorded. Despite some loss of seeded cells after inclusion in the in vitro flow circuit, the endothelial cell count was not significantly different to those recorded for control, non-cryopreserved specimens. In conclusion arterial and venous endothelial cells growing in co-culture modify their behaviour to form multilayers. The two cell populations form normal PECAM1 junctions and preserve their functional properties. Seeding autologous venous endothelial cells on the luminal surface of cryopreserved arterial segments serves to restore the integrity of the endothelial layer.

Animals↗

PubMed2004

Assessment of application-rate dependent effects of a long-term fire retardant chemical (Fire Trol 934) on Typha domingensis germination.

Although long-term fire retardants (LTR) gain increasingly acceptance as effective tools for wildfire management, recent studies indicate their potential harmfulness in the environment, especially in aquatic ecosystems. This study comprises a first laboratory impact assessment of LTR action in temporal Mediterranean wetlands, using seed germination of Typha domingensis as indicator of impact. Our aim was to identify application rates upon which seed germination could be significantly affected. We tested for low (1 l m(-2)) and high (3 l m(-2)) application rates of Fire Trol 934 which are recommended by the manufacturers as a function of fuel characteristics. In addition, we simulated the impact of a higher application rate of 5 l m(-2) because inhomogeneous dispersal of the LTR during fire control and prevention operations can result in locally elevated applications. Results of a microcosm experiment indicate that application rates of 1 or 3 l m(-2) can impact Typha germination rates in the short-term via indirect LTR-mediated effects on water quality, which suppressed necessary cues for germination. However, a subsequent experiment with Petri dishes, using seeds isolated from the LTR treated sediments did not show significantly different germination rates between the control and the treatments with application rates of 1 or 3 l m(-2). This suggests that retardant pre-application germination success could be recovered in nature once the retardant is eliminated. By contrast, seeds almost completely failed to germinate in the microcosm experiment and the subsequent Petri dish essay when an application rate of 5 l m(-2) was used. This suggests a critical level upon which Typha seed germination may be perpetually limited. Research should be extended to other plant species to provide fire managers with guidelines for environmentally safe use of LTR in the Mediterranean region.

Dose-Response Relationship, Drug↗

PubMed2002

[Idiopathic granulomatous hepatitis with bilateral orchiepididymitis and skin eruption].

We report a 52 years old male admitted for fever lasting one month, dry cough, headache and malaise. Initial laboratory work up showed an AST of 172 U/l, and ALT of 252 U/l, a GGT of 353 U/l and alkaline phosphatases of 952 U/l. An abdominal CAT scan disclosed a mild hepatosplenomegaly. A liver biopsy showed a granulomatous hepatitis. During the evolution, the patient had a left testicle swelling with darkening of the surrounding skin. A testicular ultrasound showed a bilateral orchiepidydimitis. The patient was treated with non steroidal anti-inflammatory drugs and fever subsided. Three months later, these drugs were discontinued and the patient remained asymptomatic and with normal laboratory values until 36 months of follow up.

Dermatitis↗

PubMedDate not supplied

Efavirenz-associated gynecomastia: report of five cases and review of the literature.

The prognosis of HIV infection has improved dramatically since the introduction of highly active antiretroviral therapy (HAART). However, numerous adverse effects and limitations regarding tolerability remain a concern. Lipomastia (pseudogynecomastia), a breast enlargement due to central adiposity, may occur as part of a fat redistribution syndrome which has been associated with HAART regimens and several pathogenic mechanisms have been advocated in its development. Here we report an observational longitudinal study of five patients diagnosed of gynecomastia associated with efavirenz-based HAART regimens. All cases reached successful immunologic and virologic responses to HAART. The delay of appearance of gynecomastia from the beginning of HAART ranged between 4 to 15 months. In all five cases, gynecomastia regressed after efavirenz withdrawal (mean period of 5 months). In summary, we think that HAART induced gynecomastia should be suspected in HIV patients receiving efavirenz-containing regimens. Although pathogenesis is unclear, this study and a review of the English literature implicates two possible mechanisms: (a) immune restoration processes and (b) efavirenz mediated estradiol-like effects.

Adult↗