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Biomedical subjects

A Marcos

Publications and source records attributed to A Marcos.

At least 55 records · Page 3Linked to original sources
PubMed2001

Nutrition and cognitive impairment in the elderly.

As the number of older people is growing rapidly worldwide and the fact that elderly people are also apparently living longer, dementia, the most common cause of cognitive impairment is getting to be a greater public health problem. Nutrition plays a role in the ageing process, but there is still a lack of knowledge about nutrition-related risk factors in cognitive impairment. Research in this area has been intensive during the last decade, and results indicate that subclinical deficiency in essential nutrients (antioxidants such as vitamins C, E and beta-carotene, vitamin B(12), vitamin B(6), folate) and nutrition-related disorders, as hypercholesterolaemia, hypertriacylglycerolaemia, hypertension, and diabetes could be some of the nutrition-related risk factors, which can be present for a long time before cognitive impairment becomes evident. Large-scale clinical trials in high-risk populations are needed to determine whether lowering blood homocysteine levels reduces the risk of cognitive impairment and may delay the clinical onset of dementia and perhaps of Alzheimer's disease. A curative treatment of cognitive impairment, especially Alzheimer's disease, is currently impossible. Actual drug therapy, if started early enough, may slow down the progression of the disease. Longitudinal studies are required in order to establish the possible link of nutrient intake--nutritional status with cognitive impairment, and if it is possible, in fact, to inhibit or delay the onset of dementia.

Aged↗
PubMed2001

Right lobe living donor liver transplantation: preoperative evaluation of the donor with MR imaging.

OBJECTIVE: The purpose of this study was to report our experience in preoperative evaluation of right hepatic lobe donors with a comprehensive MR examination and to compare abdominal MR images, MR cholangiograms, and MR angiograms with findings at surgery, intraoperative cholangiography, and digital subtraction angiography. MATERIALS AND METHODS: Twenty-eight right hepatic lobe donors underwent preoperative evaluation with MR imaging, MR cholangiography, and MR angiography. Two abdominal radiologists independently and randomly reviewed these studies. Points of assessment included focal and diffuse liver disease, calculation of right lobe volumes, depiction of the biliary tract and ductal anomalies, and depiction of the liver vasculature and vascular anomalies. Comparison was made with intraoperative cholangiograms (n = 20) and digital subtraction angiograms (n = 28). RESULTS: MR imaging revealed and characterized focal liver lesions in eight of 28 patients. Calculated right lobe volumes agreed with surgically determined volumes within 7% for reviewer 1 and within 15% for reviewer 2. Intrahepatic bile ducts were depicted completely with MR cholangiography in 25 of 28 patients and with intraoperative cholangiography in nine of 20 patients. MR cholangiography revealed ductal anomalies in six patients. MR imaging and MR angiography depicted the portal veins more completely than digital subtraction angiography. MR imaging and MR angiography correctly excluded portal venous anomalies in all patients and revealed surgically confirmed accessory hepatic veins in six of 28 patients. Angiographically confirmed arterial anomalies were correctly detected in three of 28 patients by at least one reviewer on MR imaging and MR angiography. CONCLUSION: MR imaging, MR cholangiography, and MR angiography provide a comprehensive, accurate means of evaluating donors for factors that may preclude or complicate right hepatic lobe donation.

Adult↗
PubMed2000

The interrelationship between portal and arterial blood flow after adult to adult living donor liver transplantation.

BACKGROUND: When adults are transplanted with segmental grafts, disparity between the size of the graft and the native organ is almost universal. These grafts presumably still receive all of the native portal inflow despite a reduced vascular bed and dramatically elevated blood flow may result. The hemodynamic changes after segmental transplantation in adults have not yet been studied and their clinical significance is unknown. METHODS: Portal venous and hepatic arterial blood flow were measured intraoperatively in right lobe liver donors and recipients with electromagnetic flow probes. Postoperative evolution was monitored in recipients with ultrasonography. RESULTS: Portal flow to the right lobe ranged from 601 to 1,102 ml/min before resection and from 1,257 to 2,362 ml/min after transplantation. There was a statistically significant linear correlation between the change in portal flow and graft to recipient body weight ratio. Arterial blood flow ranged from 213 to 460 ml/min before resection and from 60 to 300 ml/min after transplantation. Preoperative portal peak systolic velocity was uniformly around 10 cm/sec. Values on postoperative day 1 were increased to 30 cm/sec in recipients of cadaveric organs, to 50 cm/sec in recipients of organs with graft to recipient body weight ratios of more than 1.2%, and to 115 cm/sec in recipients of organs with ratios less than 0.9%. A decreasing tendency was universally observed. Arterial systolic velocity was inversely related to portal systolic velocity. Neither graft dysfunction nor vascular complications occurred. CONCLUSIONS: The hemodynamic pattern after right lobe transplantation is predictable and intraoperative measurements and ultrasonography are useful for monitoring. The size of the graft influences the magnitude of the hemodynamic changes.

Adult↗
PubMed2000

Selection and outcome of living donors for adult to adult right lobe transplantation.

BACKGROUND: The shortage of cadaveric livers has sparked an interest in adult-to-adult living donor transplantation. Right lobe donor hepatectomy is frequently required to obtain a graft of adequate size for adult recipients. Careful donor selection is necessary to minimize complications and assure a functional graft. METHODS: A four-step evaluation protocol was used for donor selection and satisfactory results of all tests in each step were required before proceeding to the next. Donors were selected based on a battery of laboratory studies chosen to exclude unrecognized infection, liver disease, metabolic disorders, and conditions representing undue surgical risk. Imaging studies included ultrasonography, angiography, magnetic resonance imaging, and intraoperative cholangiography and ultrasonography. The information obtained from liver biopsy was used to correct the estimated graft mass for the degree of steatosis. RESULTS: From March 1998 to August 1999, 126 candidates were evaluated for living donation. A total of 35 underwent donor right lobectomy with no significant complications. Forty percent of all donors that came to surgery were genetically unrelated to the recipient. A total of 69% of those evaluated were excluded. ABO incompatibility was the primary reason for exclusion after the first step (71%) and the presence of steatosis yielding an inadequate estimated graft mass after the second step (20%). CONCLUSIONS: Donor selection limits the application of living donor liver transplantation in the adult population. Unrelated individuals increase the size of the donor pool. Right lobe hepatectomy can be performed safely in healthy adult liver donors. Preoperative liver biopsy is an essential part of the evaluation protocol, particularly when the estimated graft mass is marginal.

Adult↗
PubMed2000

Emergency adult to adult living donor liver transplantation for fulminant hepatic failure.

BACKGROUND: The high mortality rate associated with fulminant hepatic failure combined with the limited availability of cadaveric organs requires consideration of alternatives to conventional cadaveric transplantation. Use of the donor right lobe in adult-to-adult living donor transplantation holds promise in a variety of circumstances, including high-acuity situations. METHODS: A 28-year-old male with fulminant hepatic failure secondary to hepatitis B was referred to our institution. He rapidly progressed to grade IV encephalopathy, and laboratory values were indicative of a poor prognosis without transplantation. He was listed for transplantation as UNOS status I. Three siblings were simultaneously evaluated for living liver donation. Following established protocols, we completed donor evaluation in less than 24 hr, and donor right lobectomy and living donor transplantation were performed within 36 hr of the recipient's admission to our center. RESULTS: The donor surgery was uncomplicated, and the patient was discharged on postoperative day 4. The recipient experienced full recovery and was discharged home on postoperative day 14. Of note, the first offer for a cadaveric liver came more than 60 hr after living donor transplantation. CONCLUSIONS: Thorough donor workup can be completed in less than 24 hr without inappropriate abbreviation of the evaluation. Simultaneous workup of willing individuals prevents unnecessary delay. Living donor transplantation should be considered for patients with fulminant hepatic failure who are appropriate transplant candidates.

Adult↗
PubMed2000

Emergency portacaval shunt for control of hemorrhage from a parenchymal fracture after adult-to-adult living donor liver transplantation.

As more adults undergo transplantation with partial liver grafts, the unique features of these segments and their clinical significance will become apparent. A patient presented with life-threatening hemorrhage from an iatrogenic laceration to a right lobe graft 11 days after transplantation. The creation of a portacaval shunt effectively controlled the bleeding, allowing more elective replacement of the organ with another right lobe graft. The regeneration process combined with increased portal blood flow and relative outflow limitation may have set the stage for this complication. Any disruption of the liver parenchyma during transplantation should be securely repaired and followed cautiously. Portacaval shunting is an option for controlling hemorrhage from the liver in transplant recipients. The timely availability of a second organ was likely the ultimate determinant of survival for this patient.

Adult↗
PubMed2000

Liver regeneration and function in donor and recipient after right lobe adult to adult living donor liver transplantation.

BACKGROUND: Regeneration of the liver to a predetermined size after resection or transplantation is a well described phenomenon, but the time course over which these events occur has not been well defined. It is not clear how initial liver mass, reperfusion, immunosuppression, or steatosis influence this process. METHODS: Liver regeneration was assessed prospectively by volumetric magnetic resonance imaging (MRI) in living right lobe liver donors and the recipients of these grafts. Imaging was performed at regular intervals through 60 days after resection/transplantation, and liver mass was determined. Liver function tests and synthetic function were monitored throughout the study period in donors and recipients of these grafts as well as recipients of cadaveric grafts. RESULTS: MRI consistently overestimated liver mass by a mean of 45 g (+/-65) (range 10-123). Donor liver mass increased by 101%, 110%, 115%, and 144% at 7, 14, 30, and 60 days after resection, respectively. Recipient liver mass increased by 87,101, 119, and 99% at 7, 14, 30, and 60 days after transplantation, respectively. Steatosis did not influence the degree of regeneration or graft function, nor was there a functional difference between grafts of >1% graft to recipient body weight ratio or <1%. CONCLUSIONS: MRI accurately determines right lobe mass. Most liver regeneration occurs in the 1st week after resection or transplantation, and the time course does not differ significantly in donors or recipients. The mass of the graft or remnant segment affects the duration of the regeneration process, with a smaller initial liver mass prolonging the course. Steatosis of <30% had no bearing on liver function or regeneration and, therefore, should not be an absolute criterion for exclusion of donors. A calculated graft to recipient body weight ratio of 0.8% is adequate for right lobe living donor liver transplantation.

Adult↗
PubMed2000

Right lobe living donor liver transplantation: a review.

The continuing shortage of organs for adult transplant recipients has generated enthusiasm for adult-to-adult living donor liver transplantation (LDLT). The major concern has been the ability to resect a graft of adequate size without subjecting the donor to undue risk. The right hepatic lobe is generally large enough for adult recipients, but because of the real and perceived risks of right lobe (RL) resection, surgeons have been hesitant to offer this option to their patients. The first series of RL resections that included a significant number of patients was reported in 1999, and the results were encouraging. Only minor complications occurred in donors, and the recipients fared quite well. Enthusiasm for these donor resections is growing, and more centers are beginning to perform them. There is a good deal of global experience with pediatric LDLT but little with adults, and there are unique considerations in this population. This review examines donor selection criteria for adult recipients, highlights technical points critical for good outcome, and examines the early results and complications in both donors and recipients. If the preliminary results continue to be reproduced, RL LDLT could have significant impact on the worsening organ shortage.

Adult↗
PubMed2000

Nutritional status of young female elite gymnasts.

The purpose of this study was to evaluate the nutritional status of a group of 10 young female elite gymnasts aged 13-17 years, who do a physical exercise of 48 h/wk. Assessment included dietary intake for 7 days, body mass index, ideal body weight, and skinfold thickness. In addition, the number of total leukocytes, total lymphocytes and lymphocyte subsets CD2, CD3, CD4, CD8, CD19 and CD56 were counted. The results were compared with a control group consisting of 50 volunteer students doing less than 12 h/wk of physical exercise, who were matched by sex, age, and sociocultural level. The total weekly calorie intake was lower in gymnasts than in controls; gymnasts showed a higher calorie intake from dietary protein together with a lower calorie intake from lipid and carbohydrate sources in comparison with controls. All the anthropometric parameters, except height which was not different in the two groups, were lower in gymnasts than in controls. The lymphocyte and leukocyte counts were also lower in gymnasts in relation to controls, except CD19 and CD56 subsets which were similar in both groups. It is suggested that gymnasts are at risk of malnutrition, which when compounded with intense physical exercise could lead to immunosuppression in these athletes.

Adolescent↗
PubMed2000

Eating disorders: a situation of malnutrition with peculiar changes in the immune system.

Eating disorders, such as anorexia nervosa and bulimia nervosa, are significant public health concerns for a great deal of the population, and thus are even considered to be epidemics. These syndromes have a common aim: the pursuit of a desirable and extremely low weight, which is obviously very far from the ideal body weight. Therefore, these patients show abnormal food behavior, leading to a situation of malnutrition. Nutrients play an important role in the development and functionality of the immune system. Thus, the assessment of immunological parameters acquires great interest as a useful tool to evaluate the nutritional status of these patients. In addition, it is very well known that a depleted immune system as a consequence of malnutrition is linked to an increased susceptibility to infections. However, an extensive literature has pointed out that anorexic patients, even though severely malnourished, are relatively free from infectious diseases. As the immune system is altered by distorted food behaviors, such as in case of eating disorders, the awareness of the characteristics of other systems involved in these pathologies, and therefore altered, would be very helpful for the understanding of the mechanisms triggered in these syndromes. In fact, the interactions among the immune system and the remaining systems in eating disorders are beginning to be studied. Finally, the main goal is to limit the evolution of these illnesses through an early diagnosis and appropriate therapy to subsequently get a constant and definitive cure for the patients.

Anorexia Nervosa↗
PubMed2000

Right-lobe living donor liver transplantation.

1. Living donor liver transplantation (LDLT) is currently performed at about 30 centers in the United States. 2. Careful and critical evaluation of donor and recipient is required for optimal outcome. 3. Right lobe donation is preferred over left lobe donation in adult LDLT. 4. There has been 1 donor death (<0.3%) in the US experiences. Donor biliary complications occur in approximately 4% of the cases. 5. Recipient survival after adult LDLT in the United States is approximately 88%. Hepatic artery thrombosis occurs in 3% and biliary complications in 18%.

Adult↗
PubMed2000

Single-center analysis of the first 40 adult-to-adult living donor liver transplants using the right lobe.

The first adult-to-adult living donor liver transplant using the right hepatic lobe in the United States was performed only 2 years ago. Although initial reports were encouraging, continuous review of the results and appropriate modifications in patient management will be necessary to minimize donor risk and optimize recipient outcome. The results of 40 such transplantations were analyzed and are summarized. Recipients were listed for transplantation according to the usual criteria. Living donors were not considered for United Network for Organ Sharing status IIA patients after the initial 22 patients. Donor evaluation followed a rigid protocol. A graft-to-recipient body weight ratio of at least 0.8% was the minimum required throughout most of the study. The surgical procedures were similar, except the plane of transection was modified to better accommodate donor biliary anatomy, and uniform stenting of bile ducts was practiced after the first 10 transplants. Immunosuppression consisted of tacrolimus, mycophenolate mofetil, and a prednisone taper. The target tacrolimus level was decreased and mycophenolate was withdrawn more rapidly in the second half of the study because of the absence of acute cellular rejection. Donor morbidity has been limited to minor complications, and transplant recipient biliary complications decreased from 35% to 0%. Acute cellular rejection has not been observed despite less aggressive immunosuppression, and septic complications decreased dramatically. There have been no recipient deaths since these changes were instituted. Right lobectomy can be performed safely in the donor population. Recipient biliary complications can be minimized with stenting. Less aggressive immunosuppression is well tolerated and minimizes septic complications and attributable mortality.

Adult↗
PubMed2000

Surgical management of anatomical variations of the right lobe in living donor liver transplantation.

OBJECTIVE: To review the anatomical variations of the right lobe encountered in 40 living liver donors, describe the surgical management of these variations, and summarize the results of these procedures. SUMMARY BACKGROUND DATA: Anatomical variability is the rule rather than the exception in liver and biliary surgery. To make effective use of liver segments from living donors for transplantation, surgical techniques must be adapted to the anomalies. METHODS: Donor evaluation included celiac and mesenteric angiography with portal phase, magnetic resonance angiography, and intraoperative ultrasonography and cholangiography. Arterial anastomoses were generally between the donor right hepatic artery and the recipient main hepatic artery. Jump-grafts were constructed for recipients with hepatic artery thrombosis, and double donor arteries were joined to the bifurcation of the recipient hepatic artery. The branches of a trifurcated donor portal vein were isolated during the parenchymal transection, joined in a common cuff, and anastomosed to the recipient main portal vein. Significant accessory hepatic veins were preserved, brought together in a common cuff if multiple, and anastomosed to the recipient cava. The bile ducts were individually drained through a Roux-en-Y limb, and stents were placed in most patients. RESULTS: Forty right lobe liver transplants were performed between adults. No donor was excluded because of prohibitive anatomy. Seven recipients had a prior transplant and five had a transjugular intrahepatic portosystemic shunt (TIPS). Arterial anomalies were noted in six donors and portal anomalies in four. Arterial jump-grafts were required in three. Sixteen had at least one significant accessory hepatic vein, and one had a double right hepatic vein. There were no vascular complications. Multiple bile ducts were found in 27 donors. Biliary complications occurred in 33% of patients without stents and 4% with stents. CONCLUSIONS: Anatomical variations of the right lobe can be accommodated without donor complications or complex reconstruction. Previous transplantation and TIPS do not significantly complicate right lobe transplantation. Microvascular arterial anastomosis is not necessary, and vascular complications should be infrequent. Biliary complications can be minimized with stenting.

Adult↗
PubMed2000

Altered glycosylation of acetylcholinesterase in lumbar cerebrospinal fluid of patients with Alzheimer's disease.

As clinical diagnosis of Alzheimer's disease is only 80%-90% accurate, there is a need to identify biochemical markers of Alzheimer's disease. Previous studies have shown an abnormality in the glycosylation of acetylcholinesterase (AChE) in the CSF collected postmortem from patients with Alzheimer's disease. This abnormality was very specific for Alzheimer's disease, as it was not detected in other illnesses causing dementia. We report here that the glycosylation of AChE is also altered in lumbar CSF collected antemortem. The altered glycosylation was due to increased concentrations of a minor AChE isoform that does not bind to concanavalin A (Con A). Glycosylation of AChE may eventually be of diagnostic value, especially when used in combination with other CSF markers.

Acetylcholinesterase↗
PubMed1999

Right lobe living donor liver transplantation.

BACKGROUND: The shortage of livers for transplantation has prompted transplant centers to seek alternatives to conventional cadaveric liver transplantation. Left lateral segmentectomy from living donors has proven to be a safe operation for the donor with excellent results in the pediatric population. Left lobectomy, conceived to supply more tissue, still provides insufficient liver mass for an average size adult patient. Right lobectomy could supply a graft of adequate size. METHODS: Donors were considered only after recipients were listed according to United Network for Organ Sharing (UNOS) criteria. Donor evaluation included liver biopsy, magnetic resonance imaging, and celiac and mesenteric angiography. The donor operation consisted of a right lobectomy uniformly performed throughout the series as described herein. RESULTS: Twenty-five right lobe living donor liver transplants were performed between adults, with no significant complications in donors. Recipient and graft survival was 88%, with three recipient deaths secondary to uncontrolled sepsis in patients at high risk for liver transplant; all three had functioning grafts. CONCLUSIONS: Right lobe living donor liver transplantation poses challenges that require a meticulous surgical technique to minimize morbidity in the recipient. Right lobectomies for living donation can be performed safely with minimal risk to both donor and recipient although providing adequate liver mass for an average size adult patient.

Adult↗
PubMed1999

Central venous catheter exchange by guidewire for treatment of catheter-related bacteraemia in patients undergoing BMT or intensive chemotherapy.

Current guidelines for the treatment of catheter-related bacteraemia (CRB) advise against central venous catheter (CVC) exchange because of the potential risk of prolonging infection. However, there are no consistent data proving this recommendation. We evaluated prospectively the usefulness of CVC exchange by guidewire for the treatment of CRB in patients undergoing BMT or intensive chemotherapy. CVC exchange was considered when fever and positive blood cultures persisted after 2 days of adequate antimicrobial therapy and no potential source of bacteraemia other than CVC could be identified. The guidewire exchange was preceded and followed by a slow infusion of adequate antimicrobial therapy. Bacteraemia was confirmed as catheter-related by demonstrating concordance between isolates from the tip and blood cultures by pulsed-field electrophoresis of genomic DNA. This procedure was performed in 19 episodes of bacteraemia during a 1-year period. Fourteen episodes (74%) were catheter-related and 71% of these were due to coagulase-negative staphylococci. Guidewire replacement was accomplished uneventfully 4 days after development of sepsis (range 3-6). In all cases, clinical signs of sepsis disappeared in less than 24 h after replacement. Definitive catheter withdrawal was carried out a median of 16 days (range 3-42) after guidewire exchange; in all cases, the tip culture was negative. We conclude that CVC replacement by guidewire under adequate antimicrobial therapy may be a reasonable option for the treatment of CRB when antimicrobial therapy alone has been unsuccessful.

Adult↗