Papers by Rodrigo Gonzalez
First record of flamentous fungi in the coastal upwelling ecosystem off central Chile
... Marcelo H. Gutiérrez 1,4 , Silvio Pantoja 2,4 , Renato A. Quiñones 2,4 & Rodrigo R. Gonzá... more ... Marcelo H. Gutiérrez 1,4 , Silvio Pantoja 2,4 , Renato A. Quiñones 2,4 & Rodrigo R. González 3. ... Canadian Journal Microbiology 47: 829-841. [ Links ]. Montero, P, G. Daneri, EA Cuevas, HE González, B. Jacob, L. Lizárraga & E. Menschel. 2007. ...
Diplodon chilensis is a freshwater bivalve inhabiting from northern Chile to Tierra del Fuego. Th... more Diplodon chilensis is a freshwater bivalve inhabiting from northern Chile to Tierra del Fuego. This species has a high filtration capacity and great tolerance to hypoxic environments. Thus, the aim of this study was to characterize, for the first time, anaerobic metabolism of D. chilensis using an enzymatic approach by measuring piruvate oxidoreductases and malate dehydrogenase activities in two groups
Progress in Oceanography, 2007
The effects of the oxygen minimum zone on the metabolism of the heterotrophic microplankton commu... more The effects of the oxygen minimum zone on the metabolism of the heterotrophic microplankton community (0.22-100 lm) in the Humboldt Current System, as well as the factors controlling its biomass production, remain unknown. Here we compare the effect of four sources of dissolved organic carbon (glucose, oxaloacetate, glycine, leucine) on microbial biomass production (such as ATP-P) and the potential enzymatic activities involved in catabolic pathways under oxic and suboxic conditions. Our results show significant differences (p < 0.05) in the ATP-P production when induced by the different substrates that are used as dissolved organic carbon herein. The induction of ATP-P production is enhanced from glucose < oxaloacetate < glycine < leucine. Nevertheless, for individual substrates, no significant differences were found between incubation under oxic and suboxic conditions except in the case of leucine. For this amino acid, the induction of ATP-P synthesis was higher under suboxic than oxic conditions. The data sets of all the substrates used showed greater potential ATP-P production under suboxic than oxic conditions. The results of the potential enzymatic activities suggest that malate dehydrogenase has the highest signal of NADH oxidization activity in the microbial assemblage. Furthermore, for all experiments, the malate dehydrogenase activity data set had a significant relationship with ATP-P production. These findings suggest that the microbial community inhabiting the oxygen minimum zone has the same or greater potential growth than the community inhabiting more oxygenated strata of the water column and that malate dehydrogenase is the activity that best represents the metabolic potential of the community.
Gayana (Concepción), 2006
Respiration is a key variable to understand the flux of energy and matter in any ecosystem. In fa... more Respiration is a key variable to understand the flux of energy and matter in any ecosystem. In fact, ecosystem respiration is a critical component of the carbon cycle and might be important in regulating biosphere response to global climate change. Respiration is the basic process used by the biota to yield energy from the degradation of organic matter for their survival needs, its measurement provides an estimate of the minimum energy needed by the organism. Accordingly, the total respiration of an aquatic community can be equated to the minimum energy needed to maintain its organized living structure and function. Despite its importance, community respiration has been a process scarcely studied in the ocean and only during the 90's has become more relevant. In fact, whereas aerobic metabolism has been scarcely studied in ocean systems, anaerobic metabolism, especially at the community level of organization, has been largely neglected.
Gayana (Concepción), 2003
Emerita analoga (Stimpson 1857) habita en la zona infralitoral de playas arenosas, desarrollando ... more Emerita analoga (Stimpson 1857) habita en la zona infralitoral de playas arenosas, desarrollando intensa movilidad en la zona de barrido y embate de las olas. Su habilidad motriz, reflejada en una constante actividad muscular explosiva, sugiere una alta actividad glicolítica (fermentativa) complementaria a la fosforilación oxidativa. En este trabajo se determinó la actividad específica aparente de la láctico dehidrogenasa (LDH EC 1.1.1.27) de E. analoga como indicador de hipoxia funcional. Además, se estudió el efecto del peso y del pH sobre la actividad LDH, así como en los valores aparentes de sus parámetros cinéticos (V max y K m ). Los resultados indican que los organismos grandes (> a 1,5) y pequeños (< a 1,5 mm) de E. analoga, se ajustan a una curva alométrica actividad -peso positiva (p = 0,0108). El pH óptimo de la LDH es 7,8 para animales pequeños y de 5,5 en animales grandes. Esto sugiere que la acidosis metabólica podría ser regulada a escala enzimática en los animales pequeños y como tampón muscular en los grandes. Para los dos tamaños la LDH mostró una cinética Michaeliana, siendo el V max de los animales grandes de un orden de magnitud mayor que en los pequeños (1,043 y 0,121 mmol min -1 g wet wt -1 respectivamente). Sin embargo, se observó una mayor afinidad (menor valor de la constante de Michaelis) en los organismos pequeños que en los grandes (0,076 y 0,094 mM respectivamente). Finalmente, la pendiente positiva de la curva actividad -peso concuerda con la alometría del metabolismo anaeróbico escasamente descrito e inverso a la pendiente del aeróbico. Esto sugiere que la LDH tendría un rol importante en la movilidad de E. analoga durante su ontogenia en la zona infralitoral.
During the1997-98 El Ni~no event, the tempera- ture and oxygen contents of the coastal waters o n... more During the1997-98 El Ni~no event, the tempera- ture and oxygen contents of the coastal waters o northern Chile were noticeably higher than during non-El Ni~no con- ditions, butphytoplanktonandzooplanktonbiomasses were not dramatically altered. In contrast, the herbivorous cope- pod Calanus chilensis, which showed a limited tolerance to low-oxygenconditions,exhibitedgreaterabundances,higher growth rates, and a signicant reduction in adult body size. These results indicate
Estuarine Coastal and Shelf Science, 2000
The presence of low oxygen conditions in extensive areas of the continental shelf off central-sou... more The presence of low oxygen conditions in extensive areas of the continental shelf off central-south Chile has important effects on the biochemical adaptations of the organisms living in this ecosystem. Polychaetes assemblages cohabit on the shelf with an extensively distributed prokaryotic community made up of giant filamentous sulfur bacteria (mainlyThioploca sp.). The aim of this research was to characterize the
Geophysical Research Letters, 2001
During the 1997-98 El Niño event, the temperature and oxygen contents of the coastal waters off n... more During the 1997-98 El Niño event, the temperature and oxygen contents of the coastal waters off northern Chile were noticeably higher than during non-El Niño conditions, but phytoplankton and zooplankton biomasses were not dramatically altered. In contrast, the herbivorous copepod Calanus chilensis, which showed a limited tolerance to low-oxygen conditions, exhibited greater abundances, higher growth rates, and a significant reduction
Evaluación de la cicatrización del primer episodio de luxación anterior de hombro de origen traumático mediante resonancia magnética en pacientes tratados con inmovilizador en rotación externa: reporte de dos casos
Although infrequently used as a first line treatment for anterior glenohumeral dislocation, exter... more Although infrequently used as a first line treatment for anterior glenohumeral dislocation, external rotation and abduction immobilization is a non-surgical option in those cases. This case report is about the conservative management of two young patients, a soldier and a basketball player, who were treated with acute close reduction and immobilization with an abduction and external rotation brace during four
Aerobic and anaerobic metabolism of Paraprionospio pinnata (Polychaeta: Spionidae) in central Chile
Journal of the Marine Biological Association of the UK, 2007
Page 1. J. Mar. Biol. Ass. UK (2007), 87, 459463 Printed in the United Kingdom Journal of the Ma... more Page 1. J. Mar. Biol. Ass. UK (2007), 87, 459463 Printed in the United Kingdom Journal of the Marine Biological Association of the United Kingdom (2007) doi: 10.1017/ S0025315407048710 Aerobic and anaerobic metabolism of Paraprionospio pinnata ...
Estuarine, Coastal and Shelf Science, 2000
The presence of low oxygen conditions in extensive areas of the continental shelf off central-sou... more The presence of low oxygen conditions in extensive areas of the continental shelf off central-south Chile has important effects on the biochemical adaptations of the organisms living in this ecosystem. Polychaetes assemblages cohabit on the shelf with an extensively distributed prokaryotic community made up of giant filamentous sulfur bacteria (mainly Thioploca sp.). The aim of this research was to characterize the pyruvate oxidoreductases enzymes involved in the biochemical adaptation of these benthic polychaetes. Nine polychaete species (Paraprionospio pinnata, Nephtys ferruginea, Glycera americana, Haploscoloplos sp., Lumbrineris composita, Sigambra bassi, Aricidea pigmentata, Cossura chilensis, and Pectinaria chilensis) were assayed for lactic dehydrogenase (LDH), octopine dehydrogenase (OPDH), strombine dehydrogenase (STRDH) and alanopine dehydrogenase (ALPDH). Each species had a characteristic number of the pyruvate oxidoreductases assayed ranging from 4 in Paraprionospio pinnata to 1 in Pectinaria chilensis. The pyruvate saturation curves obtained for the enzymes from all species analysed, except L. composita, suggest that NADH can be oxidized at different rates depending on the amino acid used in the reaction with pyruvate. Our results indicate that organisms having more that one pyruvate oxidoreductase present a greater metabolic capacity to cope with functional and environmental hypoxia because these enzymes would better regulate the pyruvate consumption rate during the transition period. Thus, the dominance of Paraprionospio pinnata in the study area and its worldwide distribution is consistent with its higher number of pyruvate oxidoreductases with different pyruvate consumption rates involved in anaerobic metabolism. Finally, a positive allometric relationship was found between body size and the specific activity of ALPDH, STRDH, and maximum pyruvate oxidoreductase specific activity. This latter result suggests a positive scaling of the specific anaerobic metabolism in polychaetes.
Continental Shelf Research, 2011
We studied for the first time the intertidal and subtidal gas seepage system in Mocha Island off ... more We studied for the first time the intertidal and subtidal gas seepage system in Mocha Island off Central Chile. Four main seepage sites were investigated (of which one site included about 150 bubbling points) that release from 150 to 240 tonnes CH 4 into the atmosphere per year. The total amount of methane emitted into the atmosphere is estimated in the order of 800 tonnes per year. The gases emanated from the seeps contain 70% methane, and the stable carbon isotopic composition of methane, d 13 C-CH 4 averaged À 44.4 71.4% which indicates a major contribution of thermogenic gas. Adjacent to one of the subtidal seeps, rocky substrates support a diverse community of microbial filaments, macroalgae, and benthic organisms. While stable carbon isotopic compositions of marine benthic organisms indicate a dominant photosynthesis-based food web, those of some hard-substrate invertebrates were in the range À 48.8% to À 36.8%, suggesting assimilation of methane-derived carbon by some selected taxa. This work highlights the potential subsidy of the trophic web by CH 4 -C, and that its emission to the atmosphere justifies the need of evaluating the use of methane to support the energy requirements of the local community.
Operative Technique for Converting a Failed Vertical Banded Gastroplasty to Roux-en-Y Gastric Bypass
Bariatric surgeons are increasingly encountering patients with failed weight-loss operations. Con... more Bariatric surgeons are increasingly encountering patients with failed weight-loss operations. Conversion from vertical banded gastroplasty (VBG) to Roux-en-Y gastric bypass (RYGB) is the most common revisional operation in our practice. We reviewed our experience in converting from VBG to RYGB using a basic five-step surgical technique. We reviewed data on all patients undergoing revisional surgery for failed VBG, defined as patients with body mass index &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;/=35 kg/m(2), weight gain, poor control of comorbidities, staple-line dehiscence, or band-specific complications. The five basic steps include identification of the band, delineation of the extent of the pouch, division of the stomach, preparation of the Roux limb, and completion of the cardiojejunostomy. We have undertaken 28 conversions from VBG to RYGB. Median age was 51 years (range 27 to 65 years), preoperative body mass index was 40 kg/m(2) (range 20 to 58 kg/m(2)), and 25 patients (89%) were women. Indications for revision were band-related complications (13 patients), staple-line disruption (9 patients), and inadequate weight loss (6 patients). Median operative time was 185 minutes (range 105 to 465 minutes), estimated blood loss was 450 mL (range 100 to 2,500 mL), postoperative complications occurred in 6 patients (21%), and length of hospitalization was 5 days (range 3 to 69 days). Median postoperative body mass index was 32 kg/m(2) (range 20 to 41 kg/m(2)) at a followup time of 16 months (range 1 to 32 months). The technique described facilitates the operative approach to patients with failed VBG, providing guidelines for safe dissection and division of the gastric pouch for conversion to RYGB. Revisional bariatric operations are technically difficult and are associated with relatively higher complication rates than those reported for primary operations.
Operations rank and select over a sequence of symbols have many applications to the design of suc... more Operations rank and select over a sequence of symbols have many applications to the design of succinct and compressed data structures managing text collections, structured text, binary relations, trees, graphs, and so on. We are interested in the case where the collections can be updated via insertions and deletions of symbols. Two current solutions stand out as the best in the tradeoff of space versus time (when considering all the operations). One solution, by Mäkinen and Navarro, achieves compressed space (i.e., nH 0 + o(n log σ) bits) and O(log n log σ) worst-case time for all the operations, where n is the sequence length, σ is the alphabet size, and H 0 is the zero-order entropy of the sequence. The other solution, by Lee and Park, achieves O(log n(1 + log σ log log n )) amortized time and uncompressed space, i.e. n log 2 σ + O(n) + o(n log σ) bits. In this paper we show that the best of both worlds can be achieved. We combine the solutions to obtain nH 0 + o(n log σ) bits of space and O(log n(1 + log σ log log n )) worst-case time for all the operations. Apart from the best current solution to the problem, we obtain several byproducts of independent interest applicable to partial sums, text indexes, suffix arrays, the Burrows-Wheeler transform, and others.
Laparoscopic versus open umbilical hernia repair
JSLS : Journal of the Society of Laparoendoscopic Surgeons / Society of Laparoendoscopic Surgeons
The use of prosthetic material for open umbilical hernia repair has been reported to reduce recur... more The use of prosthetic material for open umbilical hernia repair has been reported to reduce recurrence rates. The aim of this study was to compare outcomes after laparoscopic versus open umbilical hernia repair. We reviewed all umbilical hernia repairs performed from November 1995 to October 2000. Demographic data, hernia characteristics, and outcomes were compared. Of the 76 patients identified, 32 underwent laparoscopic repair (LR), 24 primary suture repairs (PSR), and 20 open repairs with mesh (ORWM). Preoperative characteristics were similar between groups. Hernia size was similar between LR and ORWM groups, and both were larger than that in the PSR group. ORWM compared with the other techniques resulted in longer operating time, more frequent use of drains, higher complication rates, and prolonged return to normal activities (RTNA). The length of stay (LOS) was longer in the ORWM than in the PSR group. When compared with ORWM, LR resulted in lower recurrence rates. LR resulted ...
Components separation technique and laparoscopic approach: a review of two evolving strategies for ventral hernia repair
The American surgeon, 2005
When faced with large ventral hernias, surgeons frequently must choose between higher incidence o... more When faced with large ventral hernias, surgeons frequently must choose between higher incidence of recurrence after primary repair and higher incidence of wound complications after repair with mesh. The aim of this study is to compare early outcomes between laparoscopic repair (LR) and components separation technique (CST), two evolving strategies for the management of large ventral hernias. We reviewed 42 consecutive patients who underwent CST and 45 consecutive patients who underwent LR of ventral hernia defects of at least 12 cm2. Demographics, hernia characteristics, and short-term outcomes were compared between groups. Patients in the LR group were younger (53 +/- 2 vs 68 +/- 2 years, P < 0.0001), had greater body mass index (34 +/- 2 vs 29 +/- 1 kg/m2, P = 0.02), and had larger hernia defects (318 +/- 49 vs 101 +/- 16 cm2, P < 0.0001) than patients in the CST group. The LR resulted in shorter length of hospital stay (4.9 +/- 0.9 vs 9.6 +/- 1.8 days, P < 0.0001), lower...
Consequences of conversion in laparoscopic colorectal surgery
Diseases of the colon and rectum, 2006
Laparoscopic procedures converted to open approaches have been associated with higher complicatio... more Laparoscopic procedures converted to open approaches have been associated with higher complication rates than laparoscopic and open cholecystectomy and appendectomy. Laparoscopic colorectal resections have relatively high conversion rates compared with other laparoscopic procedures. This study was designed to evaluate outcomes of conversions compared with laparoscopic and open colorectal resections. We reviewed 498 consecutive colorectal resections performed between 1995 and 2002. Procedures were divided into laparoscopic colorectal resections, open colorectal resections, or conversions. Demographics, underlying disease, type of procedure performed, and operative outcomes were compared between groups. Of the 238 laparoscopic procedures performed, 182 were completed laparoscopically and 56 (23 percent) required conversion; 260 were performed open. Conversions were associated with greater blood loss (200 (range, 50-750) vs. 100 (range, 30-900) ml), longer time to first bowel movement ...
Preoperative Evaluation and Intraoperative Care of the Obese
Management of Morbid Obesity, 2005
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Papers by Rodrigo Gonzalez