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J M Fuentes

Publications and source records attributed to J M Fuentes.

At least 19 recordsLinked to original sources
PubMed2006

Carbon dioxide pneumoperitoneum prevents mortality from sepsis.

BACKGROUND: Carbon dioxide (CO2) pneumoperitoneum has been shown to attenuate the inflammatory response after laparoscopy. This study tested the hypothesis that abdominal insufflation with CO2 improves survival in an animal model of sepsis and investigated the associated mechanism. METHODS: The effect of CO2, helium, and air pneumoperitoneum on mortality was studied by inducing sepsis in 143 rats via intravenous injection of lipopolysaccharide (LPS). To test the protective effect of CO2 in the setting of a laparotomy, an additional 65 animals were subjected to CO2 pneumoperitoneum, helium pneumoperitoneum, or the control condition after laparotomy and intraperitoneal LPS injection. The mechanism of CO2 protection was investigated in another 84 animals. Statistical significance was determined via Kaplan-Meier analysis for survival and analysis of variance (ANOVA) for serum cytokines. RESULTS: Among rats with LPS-induced sepsis, CO2 pneumoperitoneum increased survival to 78%, as compared with using helium pneumoperitoneum (52%; p < 0.05), air pneumoperitoneum (55%; p = 0.09), anesthesia control (50%; p < 0.05), and LPS-only control (42%; p < 0.01). Carbon dioxide insufflation also significantly increased survival over the control condition (85% vs 25%; p < 0.05) among laparotomized septic animals, whereas helium insufflation did not (65% survival). Carbon dioxide insufflation increased plasma interleukin-10 (IL-10) levels by 35% compared with helium pneumoperitoneum (p < 0.05), and by 34% compared with anesthesia control (p < 0.05) 90 min after LPS stimulation. Carbon dioxide pneumoperitoneum resulted in a threefold reduction in tumor necrosis factor-alpha (TNF-alpha) compared with helium pneumoperitoneum (p < 0.05), and a sixfold reduction with anesthesia control (p < 0.001). CONCLUSION: Abdominal insufflation with CO2, but not helium or air, significantly reduces mortality among animals with LPS-induced sepsis. Furthermore, CO2 pneumoperitoneum rescues animals from abdominal sepsis after a laparotomy. Because IL-10 is known to downregulate TNF-alpha, the increase in IL-10 and the decrease in TNF-alpha found among the CO2-insufflated animals in our study provide evidence for a mechanism whereby CO2 pneumoperitoneum reduces mortality via IL-10-mediated downregulation of TNF-alpha.

Abdomen↗
PubMed2006

Laparoscopic surgery and the parasympathetic nervous system.

BACKGROUND: Laparoscopic surgery preserves the immune system and has anti-inflammatory properties. CO2 pneumoperitoneum attenuates lipopolysaccharide (LPS)-induced cytokine production and increases survival. We tested the hypothesis that CO2 pneumoperitoneum mediates its immunomodulatory properties via stimulation of the cholinergic pathway. METHODS: In the first experiment, rats (n = 68) received atropine 1 mg/kg or saline injection 10 min prior to LPS injection and were randomization into four 30-min treatment subgroups: LPS only control, anesthesia control, CO2 pneumoperitoneum, and helium pneumoperitoneum. In a second experiment, rats (n = 40) received atropine 2 mg/kg or saline 10 min prior to randomization into the same four subgroups described previously. In a third experiment, rats (n = 96) received atropine 2 mg/kg or saline 10 min prior to randomization into eight 30-min treatment subgroups followed by LPS injection: LPS only control; anesthesia control; and CO2 or helium pneumoperitoneum at 4, 8, and 12 mmHg. In a fourth experiment, rats (n = 58) were subjected to bilateral subdiaphragmatic truncal vagotomy or sham operation. Two weeks postoperatively, animals were randomized into four 30-min treatment subgroups followed by LPS injection: LPS only control, anesthesia control, CO2 pneumoperitoneum, and helium pneumoperitoneum. Blood samples were collected from all animals 1.5 h after LPS injection, and cytokine levels were determined by enzyme-linked immunosorbent assay. RESULTS: Serum tumor necrosis factor-alpha (TNF-alpha) levels were consistently suppressed among the saline-CO2 pneumoperitoneum groups compared to saline-LPS only control groups (p < 0.05 for all four experiments). All chemically vagotomized animals had significantly reduced TNF-alpha levels compared to their saline-treated counterparts (p < 0.05 for all), except among the CO2 pneumoperitoneum-treated animals. Increasing insufflation pressure with helium eliminated differences (p < 0.05) in TNF-alpha production between saline- and atropine-treated groups but had no effect among CO2 pneumoperitoneum-treated animals. Finally, vagotomy (whether chemical or surgical) independently decreased LPS-stimulated TNF-alpha production in all four experiments. CONCLUSION: CO2 pneumoperitoneum modulates the immune system independent of the vagus nerve and the cholinergic pathway.

Animals↗
PubMed2005

Haemodynamic strategy for treatment of diastolic anterograde giacomini varicose veins.

OBJECTIVES: To assess the diagnosis and outcome of a haemodynamic strategy for the treatment of primary varicose veins associated with anterograde diastolic flow (ADF) in the Giacomini vein (GV). METHODS: ADF in the GV, with the escape point located at the saphenopopliteal junction, was demonstrated in 15 patients (15 limbs) by duplex ultrasound. No other escape points were seen in this group. ADF was defined as the flow present in the relaxing phase after isometric contraction of the lower limb, measured in the standing position. Duplex and clinical follow-up was performed prospectively at 1 week, at 1, 3, 6, and 12 months and once per year thereafter, between 1998 and 2001. Surgery consisted of flush division of the GV from the small saphenous vein (SSV) and division of the incompetent collateral veins from the GV. RESULTS: GV diameter showed an average reduction from 6 to 4 mm 33 months after surgery. Fourteen patients (93%) showed no symptoms or varicose veins. GV reconnection and recurrent ADF was demonstrated in two patients (13%). CONCLUSIONS: ADF is a rare condition associated with primary varicose veins. ADF occurs when there is a closed venovenous shunt with recirculation in the muscular diastole. This implies that, although a part of the circuit is ascendant, the re-entry point must be located downstream to the escape point. Accurate duplex assessment is required to distinguish this atypical haemodynamic condition from an abnormal systolic circuit bypassing a deep vein obstruction. Interruption of the GV above its junction with the SSV abolished ADF with an acceptable rate of recurrences.

Blood Flow Velocity↗
PubMed2002

Diagnostic performance of arginase activity in colorectal cancer.

Arginase activity was measured in serum and biopsy from healthy individuals and colorectal cancer patients. Arginase activity in tumor samples (87 +/- 7.7 U/g tissue) was significantly higher than in controls (40.7 +/- 3.3 U/g tissue). However, serum arginase activity did not show any significant change in both groups. Finally, the micromethod used to quantify arginase activity in this study is superior to other methods because it has increased sensitivity, requires less sample, and is less time-consuming. Arginase differences are significant, according to the t-test (P<0.05)

Arginase↗
PubMed2001

Differential regulation of nitric oxide synthase-2 and arginase-1 by type 1/type 2 cytokines in vivo: granulomatous pathology is shaped by the pattern of L-arginine metabolism.

Type 2 cytokines regulate fibrotic liver pathology in mice infected with Schistosoma mansoni. Switching the immune response to a type 1-dominant reaction has proven highly effective at reducing the pathologic response. Activation of NOS-2 is critical, because type 1-deviated/NO synthase 2 (NOS-2)-deficient mice completely fail to control their response. Here, we demonstrate the differential regulation of NOS-2 and arginase type 1 (Arg-1) by type 1/type 2 cytokines in vivo and for the first time show a critical role for arginase in the pathogenesis of schistosomiasis. Using cytokine-deficient mice and two granuloma models, we show that induction of Arg-1 is type 2 cytokine dependent. Schistosome eggs induce Arg-1, while Mycobacterium avium-infected mice develop a dominant NOS-2 response. IFN-gamma suppresses Arg-1 activity, because type 1 polarized IL-4/IL-10-deficient, IL-4/IL-13-deficient, and egg/IL-12-sensitized animals fail to up-regulate Arg-1 following egg exposure. Notably, granuloma size decreases in these type-1-deviated/Arg-1-unresponsive mice, suggesting an important regulatory role for Arg-1 in schistosome egg-induced pathology. To test this hypothesis, we administered difluoromethylornithine to block ornithine-aminodecarboxylase, which uses the product of arginine metabolism, L-ornithine, to generate polyamines. Strikingly, granuloma size and hepatic fibrosis increased in the ornithine-aminodecarboxylase-inhibited mice. Furthermore, we show that type 2 cytokine-stimulated macrophages produce proline under strict arginase control. Together, these data reveal an important regulatory role for the arginase biosynthetic pathway in the regulation of inflammation and demonstrate that differential activation of Arg-1/NOS-2 is a critical determinant in the pathogenesis of granuloma formation.

Animals↗
PubMed2001

Reducing infections among women undergoing cesarean section in Colombia by means of continuous quality improvement methods.

BACKGROUND: Improving obstetric care in resource-limited countries is a major international health priority. OBJECTIVE: To reduce infection rates after cesarean section by optimizing systems of obstetric care for low-income women in Colombia by means of quality improvement methods. METHODS: Multidisciplinary teams in 2 hospitals used simple methods to improve their systems for prescribing and administering perioperative antibiotic prophylaxis. Process indicators were the percentage of women in whom prophylaxis was administered and the percentage of these women in whom it was administered in a timely fashion. The outcome indicator was the surgical site infection rate. RESULTS: Before improvement, prophylaxis was administered to 71% of women in hospital A; 24% received prophylaxis in a timely fashion. Corresponding figures in hospital B were 36% and 50%. Systems improvements included implementing protocols to administer prophylaxis to all women and increasing the availability of the antibiotic in the operating room. These improvements were associated with increases in overall and timely administration of prophylaxis (P<.001) in both hospitals by time series analysis, with adjustment for volume and case mix. After improvement, overall and timely administration of prophylaxis was 95% and 96% in hospital A and 89% and 96% in hospital B. In hospital A, the surgical site infection rate decreased immediately after the improvements (P<.001). In hospital B, the infection rate began a downward trend before the improvements that continued after their implementation (P =.04). CONCLUSION: Simple quality improvement methods can be used to optimize obstetric services and improve outcomes of care in resource-limited settings.

Ampicillin↗
PubMed2001

Mechanisms of MPP(+) incorporation into cerebellar granule cells.

Exposure of cerebellar granule cells to 1-methyl-4-phenylpiridinium (MPP(+)) results in cell death. We have studied the implication of various membrane transporter systems on MPP(+) neurotoxicity, including the dopamine transporter system (DAT) and cationic amino acid transporters (CAT). We have showed a partial protection against MPP(+) toxicity when the dopamine transporter is inhibited by 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]4-(3-phenylpropyl)piperazinedihydrochloride (GBR-12909). However, almost full protection is only achieved by the simultaneous addition of GBR-12909 and cationic amino acids. These results suggest two ways system of MPP(+) entrance into cerebellar granule cells: the DAT with high activity and the CAT with low activity. We also demonstrated that 5,7-dichlorokynurenic acid (MK-801) failed to protect against MPP(+) exposure, evidencing that N-methyl-D-aspartate (NMDA) receptor is not involved in the MPP(+)-induced cell death.

1-Methyl-4-phenylpyridinium↗
PubMed2001

Lithium inhibits caspase 3 activation and dephosphorylation of PKB and GSK3 induced by K+ deprivation in cerebellar granule cells.

Lithium protects cerebellar granule cells from apoptosis induced by low potassium, and also from other apoptotic stimuli. However, the precise mechanism by which this occurs is not understood. When cerebellar granule cells were switched to low potassium medium, the activation of caspase 3 was detected within 6 h, suggesting a role of caspase 3 in mediating apoptosis under conditions of low potassium. In the same conditions, lithium (5 mM) inhibited the activation of caspase 3 induced by low potassium. As lithium did not inhibit caspase 3 activity in vitro, these results suggest that this ion inhibits an upstream component that is required for caspase 3 activation. Lithium is known to inhibit a kinase termed glycogen sythase kinase 3 (GSK3), which is implicated in the survival pathway of phosphatidylinositol 3-kinase/protein kinase B (PI3K/PKB). Here we demonstrate that low potassium in the absence of lithium induces the dephosphorylation, and therefore the activation, of GSK3. However, when lithium was present, GSK3 remained phosphorylated at the same level as observed under conditions of high potassium. Low potassium induced the dephosphorylation and inactivation of PKB, whereas when lithium was present PKB was not dephosphorylated. Our results allow us to propose a new hypothesis about the action mechanism of lithium, this ion could inhibit a serine-threonine phosphatase induced by potassium deprivation.

Animals↗
PubMed2000

Implications of the S-shaped domain in the quaternary structure of human arginase.

Arginase I is a homotrimeric protein with a binuclear manganese cluster. At the C-terminus of each monomer, the polypeptide chain forms an unusual S-shaped oligomerization motif where the majority of intermonomer contacts are located [Z.F. Kanyo, L.R. Scolnick, D.E. Ash, D.W. Christianson, Nature 383 (1996) 554-557]. In order to study the implication of this motif in the quaternary structure of human arginase I, we have constructed a truncated arginase lacking the 14 C-terminal amino acids, leaving Arg-308 as the last residue in the sequence. The resulting protein retains its trimeric structure, as determined by gel filtration (molecular mass 94 kDa). The same result was obtained in the presence of high ionic strength (KCl 0.5 M). Both data indicate that neither the S-shaped motif nor Arg-308 are fundamental in keeping the trimeric quaternary structure. Data obtained from intrinsic anisotropy and fluorescence intensity studies allow us to predict that the distance between the two unique tryptophans in the sequence is 2.9 nm in the native arginase and 4.1 nm for the truncated mutant. These distances allow us to assume a different conformational state in the truncated arginase without any change in its quaternary structure, suggesting that the carboxy-terminal motif is not the most prominent domain implicated in the quaternary structure of human arginase. Collisional quenching studies reinforce this possibility, since using I(-) as quenching molecule we were able to distinguish the two tryptophans in the truncated arginase. Moreover, kinetic studies show that the truncated mutant was fully active. In summary, the main conclusion about the structure of the human arginase I, derived from our study, is that the C-terminal S-shaped motif is not basic to the maintenance of the quaternary structure nor to the activity of the protein.

Amino Acid Sequence↗
PubMed1999

Different mechanisms of protection against apoptosis by valproate and Li+.

Acute treatment with valproate and Li+ was found to protect cultured cerebellar granule cells against apoptosis induced by low K+ (5 mM). Because the protection was unaffected by MK801 (N-methyl-D-aspartate receptor inhibitor), an increase in glutamate release cannot be responsible for the observed neuroprotection. Insulin also protects against low-K+-induced apoptosis of cerebellar granule cells. This protection is totally dependent on LY294002 (a phosphatidylinositol 3-kinase inhibitor). These results suggest a role for phosphatidylinositol 3-kinase in the neuroprotection induced by insulin. Likewise, and in contrast with the results observed with Li+, the protection induced by valproate is also dependent on insulin and LY294002. Moreover, valproate (a branched-chain fatty acid) does not change the plasma membrane microviscosity under physiological conditions. These results suggest that valproate protects against low-K+-induced apoptosis by acting in the phosphatidylinositol 3-kinase/protein kinase B pathway. The protection by Li+ is independent of this transduction pathway.

Animals↗
PubMed1998

Partial lithium-associated protection against apoptosis induced by C2-ceramide in cerebellar granule neurons.

Primary cultures of cerebellar granule neurons, maintained in a serum-containing medium, underwent apoptosis when exposed to C2-ceramide, as assessed by mitochondrial reduction of MTT and intranucleosomal DNA fragmentation. After an 18 h exposure to 50 microM C2-ceramide, cell viability decreased by 25-40%. Addition of lithium together with C2-ceramide resulted in a partial protection of apoptosis, which was maximal at 5 mM lithium (37% protection). When lithium was added 5 h before the apoptotic stimulus the neuroprotective effect of the ion was clearly increased (66% protection). This effect was not due to intracellular inositol depletion or inhibition of NMDA receptors. Our data broaden the nature of apoptotic insults being reversed by lithium, stressing the neuroprotective effects of the ion.

Animals↗
PubMed1996

[Anterior and anterolateral surgery of the lower cervical spine (25 years after H. Verbiest). I: Technical bases].

The anterior approach to the cervical spine is currently a worldwide traditional surgical technique used by neurosurgeons or orthopedists in the treatment of traumatic, degenerative or tumoral cervical spinal lesions. Many original rules of these techniques were raised by pioneers as R. Cloward and H. Verbiest, and are still valid. Advances in the surgical armentarium and in bio-materials markedly improved the original technique and subsequently improved the clinical results. The present course was organized for the neurosurgery trainees by the French Speaking Neurosurgical Society, and was helded during the winter meeting in December 1995. The aim of this course is to recall the basic technical principles of the microsurgical anterior cervical approach, and to discuss the main indications of this surgical treatment. Many theoretical points are strengthened by the author's personal experience and comments. Part I presents the different anterior or antero-lateral approaches which any surgeon involved in cervical spine surgery actually needs to know. Secondly, the materials and technical basis needed to achieve an interbody graft or fusion or fixation are described. Lastly, some practical applications are detailed as a microdiscectomy, a medial or lateral cervical spine decompression, and the use of acrylic plastic or prothesis for a cervical vertebral replacement.

Bone Transplantation↗
PubMed1996

[Anterior and antero-lateral surgery of the lower cervical spine (25 years after H. Verbiest). 2: Indications, results, complications)].

The present course on the anterior and antero-lateral surgical approach of the lower cervical spine was organized for the neurosurgery trainees by the French Speaking Neurosurgical Society, and was held during the winter meeting in December 1995. The aim of this course was to recall the basic technical principles of the microsurgical anterior cervical approach, and to discuss the main indications of this surgical treatment. Many theoretical points were strengthened by the author's personal experience and comments. In Part I, the technical bases of the different anterior or antero-lateral approaches were presented (1996, 42 : 105-122). In the present Part II, the main indications of the anterior surgical approach to the cervical disk or the vertebral body are detailed, and the requirement of a bone graft and/or an osteosynthesis are discussed with their consequences on the final results. Secondly, variants of the surgical technics in use in case of cervical spinal instability are commented. Then various approaches to the cervical spinal tumors and to the vertebral artery are detailed and commented. Lastly, general and specific complications of the anterior cervical approach are listed with their rate of occurrence, and their prevention and management are discussed.

Cervical Vertebrae↗
PubMed1994

Kinetics of manganese reconstitution and thiol group exposition in dialyzed rat mammary gland arginase.

1. Rat mammary gland arginase is a metallo-enzyme dependent on Mn2+, which can be only partially substituted by Cd2+. 2. Reconstitution of the activity of dialyzed arginase by manganese is a two-phase process; the second phase is independent of the cation concentration, with a half-time recovery (t1/2) of 10.77 min. 3. The apparent Km for Mn2+ is 280 microM and 10.5 microM for enzyme dialyzed for 24 and 72 hr, respectively. 4. Treatment with 5 mM EDTA at pH 6 totally inhibits enzyme activity, which is reconstituted by Mn2+. 5. Results obtained with iodoacetamide treatment suggest the existence of sulphydryl groups accessible only when the enzyme is dialyzed.

Animals↗
PubMed1994

Immunological identity of the two different molecular mass constitutive subunits of liver arginase.

A detailed understanding of the regulatory mechanisms of arginase in the cell will depend on the clarification of the origin of the two different molecular mass subunits and on the arrangements of them to constitute the native enzyme. Here, we show the immunological recognition of the 39.5 and 37.0 kDa subunits of arginase by antibodies against both subunits. We also find that the subunit stoichiometry (39.5 kDa: 37.0 kDa) present in purified arginase preparations as well as in fresh isolated microsomes and cytoplasm corresponds to 3:1, indicating high prevalence of a constant arrangement of the constitutive subunits of arginase. These findings represent evidence for a limited posttranscriptional or posttranslational modification of only a fraction of the synthesized arginase in liver.

Animals↗
PubMed1993

Parallel induction of nitric oxide and glucose-6-phosphate dehydrogenase in activated bone marrow derived macrophages.

The production of nitric oxide (NO.) and the induction of glucose-6-phosphate dehydrogenase by lipopolysaccharides (LPS) from different sources was studied in bone marrow derived macrophages (BMM phi). NO. production was found to be linked to the induction of glucose-6-phosphate dehydrogenase, suggesting the possible involvement of this enzyme in the cytotoxic mechanism resulting from the release of NO. by activated macrophages.

Animals↗
PubMed1992

Unfolding and trypsin inactivation studies reveal a conformation drift of glucose-6-phosphate dehydrogenase upon binding of NADP.

Binding of NADP to glucose-6-phosphate dehydrogenase (G6PD) from Dicentrarchus labrax liver has stabilized its native structure against thermal inactivation, guanidine hydrochloride unfolding and inactivation by tryptic digestion. The time-course of G6PD inactivation by guanidine hydrochloride in the presence of NADP has provided experimental evidence in favor of a conformational drift upon NADP binding to the bass enzyme. Based on the inactivation patterns obtained when the enzyme was treated with guanidine hydrochloride and trypsin, it is proposed that the enzyme conformation induced upon NADP binding is in slow equilibrium with the conformation stabilized in the absence of NADP. FPLC studies have shown that micromolar concentrations of NADP induced oligomerization of G6PD. In addition, the different K0.5 values of NADP binding to the enzyme, ranging from 1-2 microM (from trypsin inactivation) to 90 microM (from titration of the intrinsic fluorescence), suggest a step-wise binding of NADP to the oligomer, with negative cooperativity in the saturation process.

Animals↗