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Biomedical subjects

L F Rodriguez

Publications and source records attributed to L F Rodriguez.

13 recordsLinked to original sources
PubMed2003

Top-level modeling of an ALS system utilizing object-oriented techniques.

The possible configuration of an Advanced Life Support (ALS) System capable of supporting human life for long-term space missions continues to evolve as researchers investigate potential technologies and configurations. To facilitate the decision process the development of acceptable, flexible, and dynamic mathematical computer modeling tools capable of system level analysis is desirable. Object-oriented techniques have been adopted to develop a dynamic top-level model of an ALS system. This approach has several advantages; among these, object-oriented abstractions of systems are inherently modular in architecture. Thus, models can initially be somewhat simplistic, while allowing for adjustments and improvements. In addition, by coding the model in Java, the model can be implemented via the World Wide Web, greatly encouraging the utilization of the model. Systems analysis is further enabled with the utilization of a readily available backend database containing information supporting the model. The subsystem models of the ALS system model include Crew, Biomass Production, Waste Processing and Resource Recovery, Food Processing and Nutrition, and the Interconnecting Space. Each subsystem model and an overall model have been developed. Presented here is the procedure utilized to develop the modeling tool, the vision of the modeling tool, and the current focus for each of the subsystem models.

Astronauts↗
PubMed1997

Giant lipoma of the breast.

Lipomas of the breast are usually small, benign neoplasms which can be treated by simple excision. Diagnosis of these masses, however, can be difficult because of the normal fatty composition of the breast. A number of radiological manoeuvres have been described for diagnosing deep lipomas in the breast, yet the clinical and radiographic identification of these masses remains challenging. We present a case of giant lipoma of the breast which was not appreciated on initial clinical and radiographic evaluation, and which was later found to comprise most of the mass of the breast. Following resection, the deformed breast was reconstructed using folded dermoglandular flaps from the areas expanded by the lipoma with excellent results. This case is an excellent illustration of the difficulties associated with diagnosis of these tumours and the reconstructive options available following excision.

Adult↗
PubMed1995

Mechanisms of sepsis in acute pancreatitis in opossums.

PURPOSE: To study the incidence and pathways of colonization of the pancreas by specific bacteria in a model of necrotizing pancreatitis. METHODS: Bacteremia and splanchnic organ colonization were studied in the early course of necrotizing pancreatitis following common biliopancreatic duct ligation (BPDL) of the opossum. Nonoperated animals served as controls. Intestinal lymph nodes, liver, spleen, and pancreas were cultured following bacteremia or sacrifice. RESULTS: In opossums with sterile bile, bacteria were recovered from 28.6% of blood cultures after BPDL (n = 10) and from 12.0% in controls (n = 10, P < 0.05). Animals that underwent BPDL revealed enteric microorganisms in intestinal lymph nodes (6), liver (3), spleen (4), and pancreas (4). Ten animals carried Salmonella within their bile (5 controls, 5 BPDL animals). Following BPDL, they developed rapid bacteremia and colonization of organs, pancreatic ductal rupture, and extravasation of bacteria and bile into the interstitium. CONCLUSION: There are two possible mechanisms for the development of bacterial colonization in opossum pancreatitis: bacterial translocation of enteric organisms from gut lumen to mesenteric lymph nodes and subsequent hematogenous dissemination and transductal infestation from the biliary tract.

Acute Disease↗
PubMed1994

Benzocaine-induced methemoglobinemia: report of a severe reaction and review of the literature.

OBJECTIVE: To report a case of benzocaine-induced inethemoglobinemia and present a review of the related literature. CASE REPORT: An 83-year-old man received benzocaine topical anesthesia 600 mg prior to intubation for resection of a thyroid adenoma. The patient became severely cyanotic after induction of anesthesia. After a negative workup for common causes of cyanosis. blood co-oximetry analysis revealed a methemoglobin concentration of 54.1 percent. Intravenous methylene blue reversed the methemoglobinemia, although delayed recurrence 20 h later necessitated readministration of intravenous methylene blue. The patient developed cardiovascular instability and severe neurologic depression requiring prolonged ventilatory support. DISCUSSION: Methemoglobinemia can result from exposure to a number of drugs including benzocaine. Cyanosis, neurological and cardiac dysfunction may result when methemoglobin concentrations exceed 30 percent. Clinical diagnosis is made on the presentation of cyanosis unresponsive to oxygen administration and a distinctive arterial blood brown color; laboratory confirmation is by cooximetry. Treatment of symptomatic methemoglobinemia is by intravenous methylene blue (1-2 mg/kg) administration. Fifty-four cases of benzocaine-induced methemoglobinemia have been reported in the literature. Intubation, endoscopy/bronchoscopy, and ingestion were the most common procedures in which benzocaine administration produced methemoglobinemia. Infants and the elderly were more likely to develop toxic methemoglobinemia after benzocaine exposure. Other risk factors included genetic reductase deficiencies, exposure to high doses of anesthetic, and presence of denuded skin and mucous membranes. CONCLUSIONS: Because of the potential for severe complications, methemoglobinemia should be corrected promptly in compromised patients and those with toxic benzocaine concentrations. The possibility of masking symptoms during general anesthesia carries special risk of use of this agent in the preanesthesia setting.

Administration, Topical↗
PubMed1993

Alterations in rat intestinal transit by morphine promote bacterial translocation.

Translocation of enteric microorganisms from the intestinal tract to extraintestinal sites has been proposed as an early step in the development of gram-negative sepsis. This study examined the role of altered bowel transit in influencing intestinal bacteriostasis and bacterial translocation using morphine as a pharmacologic inhibitor of such transit. In the first experiment, either normal saline (N = 8) or morphine sulfate (20 mg/kg; N = 8) was injected subcutaneously. Two hours later, morphine (7.5 mg/kg) was infused subcutaneously for an additional 22 hr; control animals received saline alone. After completion of this regimen, a volume of 0.2 ml of 2.5 mM FITC dextrans (10,000 daltons) were injected intraduodenally in each group. The bowel was removed 25 min later, divided into 5-cm segments, and the content of dextrans measured. Small bowel propulsion was expressed as the geometric center of the distribution of dextrans throughout the intestine (in percentage length of small bowel). Gut propulsion was significantly reduced after morphine treatment as compared to controls (32.8 +/- 8.2% vs. 55.8 +/- 4.0%; P < 0.01). In 16 additional rats, saline or morphine was again administered as described. After 24 hr, samples were obtained from the mesenteric lymph node (MLN) complex, blood, spleen, liver, duodenum, jejunum, ileum, and cecum for standard bacteriology. The bacterial counts increased significantly in each intestinal segment following morphine treatment. Microorganisms translocated to the MLN complex in 5, and to distant sites in four of eight morphine-treated animals, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Effect of total parenteral nutrition plus morphine on bacterial translocation in rats.

OBJECTIVE: This study tested the hypothesis that gut stasis induced by parenteral morphine sulfate (MS) leads to enhanced bacterial translocation in rats on total parenteral nutrition (TPN). SUMMARY BACKGROUND DATA: TPN and MS are common adjuncts in the care of critically ill patients. TPN is known to provoke a variable degree of translocation. MS induces gut stasis with an accompanying bacterial overgrowth. The effect of these two treatments in combination on translocation is not known. METHODS: Rats were provided with central and subcutaneous lines for the continuous infusion of nutrients and drugs, respectively. Intestinal transit was assessed by the caudal movement of a fluorescent marker intubated into the proximal duodenum. Quantitative bacteriology was carried out from various segments of the gut and from ileocecal mesenteric lymph nodes (MLN), spleen, liver, and systemic blood obtained by cardia puncture on sacrifice at 96 hours. RESULTS: Transit was unchanged by TPN alone but prolonged when given in combination with MS. Bacterial overgrowth was also enhanced by MS and increased the bacterial translocation to MLN from 50% of animals with TPN, to 100% in those receiving both TPN and MS; the colony-forming units per MLN increased from 33 +/- 14 with TPN alone to 2079 +/- 811 (STD) with TPN plus MS. Furthermore, no bacteria were found at systemic sites with TPN alone, but in 93.3% of animals receiving TPN and MS. In a subgroup of rates provided with glutamine in TPN, the TPN plus MS effects on translocation were not reversed. CONCLUSIONS: These observations demonstrate the important role that morphine plays in promoting translocation, presumably by disrupting fasting motility and enhancing bacterial overgrowth.

Animals↗
PubMed1993

Long-term follow-up of ectopic intracardiac Greenfield filter.

Greenfield filter inferior vena caval interruption is an effective approach for pulmonary embolism prophylaxis. Serious complications, however, have been documented following migration of these filters. We report a case of Greenfield filter migration to the right side of the heart. Evaluation of these filters, as well as indications for retrieval, are discussed.

Aged↗
PubMed1993

Reevaluation of the linkage between acute hemorrhagic shock and bacterial translocation in the rat.

The present study was undertaken to determine the conditions under which acute periods of hemorrhagic shock induce bacterial translocation. Rats (at least six per group) were anesthetized intraperitoneally with the barbiturate, pentobarbital (50 or 65 mg/kg), or the inhalation anesthetic methoxyflurane. Following anesthesia, the femoral artery was catheterized, from which blood was withdrawn to maintain a mean arterial blood pressure of 30 mmHg for 30, 60, or 90 min, followed by reinfusion of shed blood. Instrumented, but nonshocked animals served as controls. Rats were sacrificed at 0, 2, or 24 hr postshock, and quantitative bacterial cultures of the mesenteric lymph node complex (MLN), liver, and spleen were made. Within groups, the effects of heparinization were also determined. In pentobarbital-treated animals, regardless of the extent of heparinization, consistent translocation to both MLN and distant organs occurred when shock was prolonged for 90 min, and assessment of translocation was made 24 hr after reinfusion of shed blood. Furthermore, a mortality rate of approximately 30% was found in rats subjected to this protocol. The magnitude of translocation was less consistent, and did not differ from that in sham shock controls, under other conditions of shock and evaluation. In rats anesthetized with methoxyflurane, no mortality occurred, and no statistical significance between the incidence or degree of translocation in shocked animals vs. sham shock controls could be demonstrated, regardless of the shock protocol. In additional studies, effects of these anesthetics on intestinal morphology and superior mesenteric arterial (SMA) flow in the context of hemorrhagic shock were assessed.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1992

Influence of shock on development of infection during acute pancreatitis in the rat.

This study tested the hypothesis that hypovolemic shock elicits or promotes the development of infection during acute pancreatitis. Pancreatitis was induced in rats by ligation of the common biliopancreatic duct; nonlaparotomized animals served as controls. After 24 hr, the animals were subjected to either sham-shock (instrumented only) or to shock by withdrawal of blood through a femoral artery line by maintaining the mean arterial blood pressure at 30 mm Hg for 1 or 2 hr. After completion of the shock period, the shed blood was returned to the animal. All animals were sacrificed 24 hr later and specimens obtained from portal and systemic blood, liver, spleen, pancreas, and mesenteric lymph nodes for bacteriologic culture using standard techniques. The pancreas was also analyzed by morphometric techniques. The histologic changes of pancreatitis induced by biliopancreatic obstruction were characterized by marked edema with accompanying mild inflammation, hemorrhage, and necrosis. Concomitant with these morphologic findings was an associated translocation of enteric organisms to the mesenteric lymph nodes without spread to distant organs. Shock by itself induced only a mild edema in the pancreas and did not cause bacterial translocation. Furthermore, shock failed to aggravate the morphologic alterations of acute pancreatitis and did not promote bacterial spread to mesenteric nodes over that observed with pancreatitis alone. Thus, we conclude that periods of severe shock lasting up to 2 hr do not play a major role in the pathogenesis of infection in our model of pancreatitis.

Acute Disease↗
PubMed1991

The role of the gut in the development of sepsis in acute pancreatitis.

The pathogenesis of sepsis in acute pancreatitis is unknown. Since the intestinal tract has recently been identified as a possible source for sepsis in other conditions, we explored whether the gut may serve as a reservoir for bacteria causing systemic and pancreatic infection in acute pancreatitis. Bacterial translocation, alterations of intestinal microflora, and intestinal motility, as reflected by gut propulsion, were studied in a rat pancreatitis model. Acute pancreatitis was induced by biliopancreatic obstruction (AP); sham manipulated animals served as controls (sham). Bacteriologic cultures were obtained from various segments of the intestinal tract and from blood, liver, spleen, pancreas, and mesenteric lymph nodes 48 and 96 hr after induction of AP or sham. Bacteria were recovered from mesenteric lymph nodes of all 12 animals with AP, but only from 3/14 sham animals (P less than 0.05). Spread to distant organ sites occurred in 4 of 12 animals with AP compared to none of the sham animals (P less than 0.05). A disruption of the intestinal microflora was found in the cecum, where the gram-negative bacterial count (log/g) was significantly higher during AP when compared with sham controls: 10.62 +/- 1.04 vs 8.05 +/- 1.45 at 48 hr and 7.92 +/- 0.62 vs 6.79 +/- 0.87 at 96 hr, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

Salmonella infection of the biliary and intestinal tract of wild opossums.

Bacteriologic cultures were taken from the mesenteric lymph nodes, biliary tract, blood, liver, spleen and pancreas of opossums (Didelphis virginiana) obtained directly from the wild for use as research animals. The overall incidence of salmonellosis outside the intestinal tract was 61% among 18 opossums. Salmonella was recovered from the gallbladder of six (33%) animals, indicating chronic biliary tract infection. Among these six animals, translocation of Salmonella to regional lymph nodes was observed in five animals, bacteremia in three animals, and spread to liver or spleen in five animals, respectively. The biliary tract was sterile in 12 opossums (67%). In these 12 animals, bacteria were isolated from the celiac and superior mesenteric lymph nodes of five animals, the blood of two animals, and the liver and spleen of one animal, respectively. Bacteriologic cultures were obtained from the intestinal tract and from extraintestinal sites in nine opossums. Salmonella were found in the small bowel of two animals, both of which had biliary salmonellosis. In addition, Salmonella was isolated from extraintestinal organs of three animals with negative cultures from the gut. All isolates identified were: S. enterica subsp houtenae. These data establish the biliary tract of wild opossums as a reservoir for Salmonella enterica subsp houtenae which may be particularly important when opossums are used in research laboratories.

Animals↗
PubMed1990

Biliary and gut function following shock.

The aim of this study was to characterize the alterations in gallbladder and intestinal function after hemorrhagic shock and blood reperfusion in opossums. Animals were subjected to a shock of 30 mm Hg of arterial blood pressure for 60 minutes and resuscitated with blood reinfusion. Gallbladder epithelial ion transport, gallbladder motility in vitro and in vivo, gastrointestinal motility, and flora of the stomach and small bowel were studied 2 and 24 hours after shock. Changes at 2 hours included decreased gallbladder contractility in vitro and decreased emptying in vivo, loss of coordination with intestinal motor activity, decrease in frequency of intestinal electrical slow waves, and reduced duration of the intestinal migrating motor complex cycle. By 24 hours, gallbladder epithelial permeability was increased and in vitro contractility remained reduced but the in vivo functions showed partial recovery. Gastrointestinal flora was not affected by these changes. These data demonstrate that hemorrhagic shock and reperfusion affect digestive motility. The early timing of the alterations observed and the partial recovery 24 hours post shock suggest an ischemia-hypoxia mechanism of injury.

Animals↗