Liver transplantation in Mexican older adults: A comparative single-center study. / Trasplante de hígado en adultos mayores mexicanos: un estudio comparativo en un solo centro.

INTRODUCTION: Liver disease is currently one of the leading causes of death in older adults and the only option deemed curative is liver transplantation. However, it is uncertain whether the successful results obtained in older adults that receive a liver transplant in developed countries can be replicated in developing countries. AIM: To determine if there are differences in the survival time between older (≥60years) and younger adults that underwent liver transplantation at a university-affiliated tertiary care center in Mexico City. MATERIALS AND METHODS: A 2-year longitudinal study was conducted. It included 244 participants that were divided into 2groups according to age at the time of transplantation: older adults (≥60years) and younger adults (18-59years). Survival time was defined as the number of days that elapsed between transplantation and death. Survival was expressed as Kaplan-Meier curves. RESULTS: Median age in the older adults (n=52) was 63.0 (IQR=60-69) and 23 participants were females (44.2%). In the younger adults (n=196) median age was 47.0 (IQR=16-59) and 104 were females (52%). The leading indication for transplant was hepatitisC virus. After the follow-up, fifteen participants died (12 younger adults and 3 older adults). No significant differences were observed between older and younger participants in postoperative complications, the number of re-admissions, or mean post-transplantation survival time. CONCLUSIONS: There were no statistically significant differences in relation to survival times between older and younger adults that received a liver transplant. Older patients in developing countries should not be excluded from the selection process due only to age.

Perceptions of aging and ageism among Mexican physicians-in-training.

INTRODUCTION: Attributing negative stereotypes to older adults (ageism) may lead to undertreatment, but little is known about the prevalence of ageism among physicians treating patients with cancer in Ibero-America. We studied stereotypes of aging among Mexican physicians-in-training. MATERIALS AND METHODS: Physicians-in-training attending an oncology meeting answered the "Negative Attributes and Positive Potential in Old Age" survey. Ten questions assessed positive characteristics of aging (PPOA; score 1-4, higher scores represent a positive perception), and four assessed negative characteristics (NAOA; score 1-4, higher score representing a negative perception). Descriptive statistics were used to analyze the questionnaires. Participants completed the "Image-of-Aging" question by writing five words describing older adults and young individuals. Each word was rated from - 5 (negative) to + 5 (positive), and presented as word clouds. RESULTS: One hundred physicians-in-training (median age 28.5) were included. For the PPOA scale, the mean score was 2.9 (SD 0.4), while for the NAOA scale it was 2.1 (SD 0.4). Perceptions of aging were better among women and trainees enrolled in geriatrics and/or oncology-related programs. In the "Image-of-Aging" questions, median rating of words describing older adults was - 2, compared to + 3 for young individuals (p < 0.001). Among words used to describe older adults, the most frequent was "frail/frailty" (n = 45), while "health" (n = 46) was the most frequent for younger individuals. CONCLUSIONS: Mexican physicians-in-training showed mostly negative perceptions of aging, exemplified by the use of negative terms to describe older adults. Creating educational initiatives aimed at decreasing ageism among oncology trainees is necessary across Ibero-America.

Frailty Is not Associated with Mistreatment.

Muscle Frailty has been previously associated with increased vulnerability for adverse health-related outcomes that could lead to social consequences such as mistreatment. The aim of this cross-sectional study is to determine the association between frailty and mistreatment in 852 community-dwelling persons aged 70 or older. Mistreatment was defined as one positive answer in the Geriatric Mistreatment Scale and frailty was used as a continuum where the greater number of positive criteria according to Fried et al. indicates a higher frailty score. Multivariate logistic regression models were run to establish this association. The mean age of participants was 77.7 years (SD=6.1). Prevalence of frailty phenotype and mistreatment were 13.9% and 20% respectively. Unadjusted analysis showed frailty score was associated with mistreatment (OR = 1.16; 95% CI 1.02 to 1.3, p=0.022). However, after adjustment, the association was no longer present. The results showed that in the presence of other geriatric syndromes such as disability or depression, frailty did not show association with mistreatment in this population.

Successful Aging, a New Challenge for Developing Countries: The Coyoacán Cohort.

OBJECTIVE: To determine the socio-demographic and health factors associated with a biomedical phenotype of successful aging (SA) among Mexican community-dwelling elderly. DESIGN, SETTING AND PARTICIPANTS: Cross-sectional study of 935 older adults aged 70 or older participating in the Mexican Study of Nutritional and Psychosocial Markers of Frailty. MEASUREMENTS: SA was operationalized in accordance with the phenotype proposed by Rowe and Kahn. Univariate and multivariate logistic regression analyses were carried out in order to identify the correlates of SA. RESULTS: The phenotype of SA was present in 10% of participants. Age (P < 0.001), illiteracy (P = 0.021), polypharmacy (P < 0.001), and physical pain (P < 0.001) were factors independently and inversely associated with the presence of the SA phenotype. The only variable positively associated with SA was good self-perceived health-status (P < 0.001). CONCLUSION: Although age is not modifiable, several other factors associated with SA are. If we are to promote SA, efforts should be made towards improving those modifiable factors negatively associated with its presence, such as pain or polypharmacy. Also, enhancing factors positively associated to it might play a role in improving wellbeing.

25-OH-Vitamin D Is Not Associated with Cognitive Performance among Mexican Community-Dwelling Older Persons.

BACKGROUND: Low cognitive performance has been associated with a wide array of adverse health-related outcomes in elderly populations. Recently, the effect of vitamin D on cognition has been studied; however, its benefits are still controversial. Moreover, most studies have been carried out on North-American and European populations where vitamin D deficiency could represent a greater public-health issue when compared to Latin American ones. OBJECTIVE: To investigate the association between 25-OH-vitamin D and cognitive performance in Mexican community-dwelling elderly. DESIGN, SETTING AND PARTICIPANTS: Cross-sectional study sample of 331 community-dwelling elderly aged 70 and older, participating in the Mexican Study of Nutritional and Psychosocial Markers of Frailty. MEASUREMENTS: Serum 25-OH-vitamin D, cognitive performance as per the Mini-Mental State Examination (MMSE) and the IST (Isaacs Set Test), as well as several elements from the comprehensive geriatric assessment. RESULTS: Mean age of participants was 79.3 years (SD 5.9), 54.1% were women. The mean serum 25-OH-vitamin D level was 59.0 (SD 23.3) nmol/L while mean MMSE score was 22.3 (SD 3.4) and mean IST score was 37.1 (SD 9.1). Although 25-OH-vitamin D levels were lower across all the definitions of low cognitive perfomance, the difference between groups was not statistically significant in any of them. CONCLUSION: No association between 25-OH-vitamin D level and cognitive performance was found in this population of Mexican community-dwelling elderly. Further investigation is required in order to clarify its existence and if so, to delineate its characteristics.

Incidence, predictors, and effects of acute kidney injury after percutaneous valve implantation.

BACKGROUND: Acute kidney injury is a common complication after surgical aortic replacement and entails a worse prognosis. Percutaneous valve implantation is an alternative to surgical replacement. We sought to elucidate incidence, predictors, and effects of acute kidney injury after percutaneous aortic valve implantation. METHODS: A cohort of consecutive patients who underwent percutaneous aortic valve implantation at one center were studied, excluding those who died in the first 24 hours and those on prior hemodialysis. RESULTS: A total of 131 patients (age, 80.8 ± 6 years; 42% male; Euroscore II, 10.27 ± 6.9) were included. Acute kidney injury was defined as a reduction >25% in glomerular filtration rate (GFR). GFR was 62.09 ± 22 mL/min/1.73 m² at baseline, 62.7 ± 25 mL/min/1.73 m² after the procedure, and 68.03 ± 25 mL/min/1.73 m² at discharge. Acute kidney injury appeared in 17 patients (13%). Of these, 11 recovered and only 6 (4.5%) showed impaired GFR >25% upon discharge. Patients with acute kidney injury showed longer hospitalization length (median 7 days [IQR, 5-12 days] vs 3 days [IQR, 2-6 days]; P=.01) and higher 30-day mortality rate (17.6% vs 0.9%; P=.01). The only independent predictor for acute kidney injury development was Euroscore II (odds ratio, 1.192; confidence interval, 1.042-1.326; P=.01). CONCLUSION: Incidence of acute kidney injury after transcatheter aortic valve implantation was 13% in our cohort. Patients with acute kidney injury showed longer hospitalization and higher 30-day mortality rate. Euroscore II was an independent predictor of acute kidney injury.

Association between Self-Reported Health Status and Frailty in Community-Dwelling Elderly.

BACKGROUND: The phenotype of frailty proposed by Fried et al. has been related with increased vulnerability for the development of adverse health-related outcomes. However, this phenotype is not often used in daily clinical practice. On the other hand, poor self-reported health status (SRHS) has been associated with similar adverse health-related outcomes. OBJECTIVES: To determine the association between poor SRHS and frailty. DESIGN, SETTING AND PARTICIPANTS: Cross-sectional study of 927 community-dwelling elderly aged 70 and older, participating in the Mexican Study of Nutritional and Psychosocial Markers of Frailty. MEASUREMENTS: SRHS was established by the question "How do you rate your health status in general?" Frailty was defined according to the phenotype proposed by Fried et al. The association between SRHS and frailty was determined through the construction of multinomial logistic regression models. Final analyses were adjusted by socio-demographic and health covariates, including depressive symptoms. Also, agreement between SRHS and the phenotype of frailty was explored. RESULTS: Prevalence of frailty was 14.1%, and 4.4% of participants rated their health status as "poor". The unadjusted regression analyses demonstrated that fair and poor SRHS were significantly associated with prefrail and frail status. After adjustment for multiple covariates, the association remained statistically significant. However, in the final adjustment for depressive symptoms, only the association between poor SRHS and frail status continued to be statistically significant. Fair agreement between poor SRHS and frail status was also found. CONCLUSION: Poor SRHS shares common correlates as well as health-related adverse outcomes with frailty syndrome, and remains associated with it even when possible confounders are taken into account. Therefore, poor SRHS could be further explored as an option for frailty syndrome screening.

The Phenotype of Frailty and Health-Related Quality of Life.

BACKGROUND: Frailty is a multidimensional problem in the elderly, but there is little information about its implications on health-related quality of life (HRQoL). OBJECTIVES: To determine the association between frailty and HRQoL as well as the association between each component of the phenotype of frailty and the physical (PCS) and mental (MCS) components summaries of QoL. DESIGN, SETTING AND PARTICIPANTS: Cross-sectional study of 496 community-dwelling elderly aged 70 and older, participating in the Mexican Study of Nutritional and Psychosocial Markers of Frailty. MEASUREMENTS: Frailty was defined by the presence of at least three of the following criteria: weight loss, exhaustion, low physical activity, slowness, and weakness. QoL and both of its components were assessed through the SF-36. The association of each component of frailty with the PCS and the MCS of QoL was determined through the construction of multivariate lineal regression models. Final analyses were adjusted by socio-demographic characteristics and by the remaining four components of frailty as covariates. RESULTS: Mean age of participants was 78.0 (SD ± 6.2), 49.4% were women, and 12.7% were frail. Multivariate lineal regression analysis showed that frail and prefrail participants had lower scores for the PCS (P < .001) and the MCS (P < .001) of QoL in comparison with non-frail subjects. Weight loss (P < .001) and exhaustion (P < .001) had an independent inverse association with the MCS of QoL while gait speed (P < .001) and grip strength (P < .001) were also inversely associated with the PCS score. CONCLUSION: Frailty is independently associated with lower scores in the MCS and the PCS of QoL. The finding that different components of frailty were associated with both dimensions of QoL reflects the need for individualized treatment of frail elderly.

The Phenotype of Frailty Predicts Disability and Mortality among Mexican Community-Dwelling Elderly.

BACKGROUND: Frailty represents a major public health priority in Western countries. Specific social and cultural factors may influence the prevalence and predictive value for negative health-related events of this syndrome. OBJECTIVE: To determine the prevalence and predictive value of the phenotype of frailty among community-dwelling Mexican American older persons. DESIGN, SETTING AND PARTICIPANTS: Two-year longitudinal study of 5,644 men and women aged 60 years and older participating in the Mexican Health and Aging Study. MEASUREMENTS: The Frailty index used in the present study was a modified version of the operational definition proposed in the Cardiovascular Health Study (CHS). Frailty was defined by the presence of at least three of the four following criteria: weight loss, weakness, exhaustion, slowness, and low physical activity. The main outcomes were incident disability and mortality. Chi-square, ANOVA and multiple logistic regression analyses were used to test the prognostic value of frailty for the outcomes of interest. RESULTS: The mean age of the study sample was 68.7 (SD 6.9) years. Thirty-seven percent of participants (n=2,102) met the definition of frailty. Frail subjects were significantly older, and more likely to be women than non-frail participants. They also presented lower education, more chronic diseases, lower income, and poorer self-reported health status. After adjusting for potential confounders, frailty was found to be a predictor of incident mobility disability (odds ratio [OR] 1.91, 95% confidence interval [CI] 1.37-2.66), activities of daily living (ADL) disability (OR 9.33; 95%CI 3.37-25.82), and instrumental ADL (IADL) disability (OR 1.81, 95%CI 1.23-2.68). The risk of mortality among frail participants was almost three-fold higher than in non-frail ones. CONCLUSION: The prevalence of frailty is higher in this elderly population than what previously reported in other cohorts. The phenotype of frailty was confirmed to be a predictor for adverse health-related outcomes (including mobility, ADL, and IADL disability). Further studies in Latin American countries are needed to identify frailty and develop adapted interventions for the prevention of adverse outcomes in older persons.

Independent predictors of renal dysfunction after heart transplantation in patients with normal pretransplant renal function.

BACKGROUND: Renal dysfunction (RD) is a common complication after heart transplantation (HT), but predictors of post-HT RD have not been clearly identified. METHODS: We studied 262 HT patients (mean age 54 years, 221 men) with normal baseline renal function. Potential risk factors examined were age, sex, pre-HT ischemic cardiomyopathy, pre- and post-HT diabetes mellitus, pre- and post-HT arterial hypertension, initial immunosuppressive protocol (before 1998 [high cyclosporine, azathioprine, and prednisone] vs after 1998 [low cyclosporine, mycophenolate mofetil, and prednisone]), occurrence of rejection episodes > or =ISHLT Grade 3A, and creatinine level 1 month after HT. RD was considered mild if creatinine level was 1.5 to 2.5 mg/dl, moderate if creatinine level was >2.5 mg/dl, and severe if dialysis or kidney transplant was required. RESULTS: The cumulative incidence of RD (creatinine >1.5 mg/dl) was 35% at 12 months, 42% at 24 months, and 47% at 60 months (mean follow-up 59 +/- 31 months). Only 1% of patients had severe RD 60 months after HT. Independent predictors of RD 24 months after HT were older age (odds ratio [OR] 1.1 [95% confidence interval (95% CI) 1.0-1.1]; p = 0.001), male sex (OR 3.3 [95% CI 1.3-8.1]; p = 0.008), pre-1998 immunosuppressive protocol (OR 2.8 [95% CI 1.4-5.4]; p = 0.003), and creatinine level 1 month after HT (OR 3.2 [95% CI 1.0-5.4]; p < 0.0001). CONCLUSIONS: The cumulative incidence of RD in HT patients treated with calcineurin inhibitors increased with time after HT. Age, male sex, an immunosuppressive protocol with relatively high cyclosporine levels and creatinine level 1 month after HT were independent predictors of the presence of RD 24 months after HT.

The role of genomics in approaching the study of Borrelia DNA replication.

The identification of chromosomal and episomal origins of replication in the genome of the causative agent of Lyme disease, the spirochete Borrelia burgdorferi, has been greatly facilitated by genomics. Analysis of genome features, including strand compositional asymmetries, organizational similarities to other bacterial origins of replication, and the presence of homologues of genes involved in replication and partitioning, have contributed to the identification of a collection of putative origins of replication within the Borrelia genome. This analysis has provided the basis for the experimental verification of origins in the linear chromosome and in the linear plasmid Ip28-2. Information generated during the study of these origins will significantly contribute to the understanding of the mechanisms of replication and partitioning in Borrelia.

Cell division inhibitors SulA and MinC/MinD block septum formation at different steps in the assembly of the Escherichia coli division machinery.

SulA and MinCD are specific inhibitors of cell division in Escherichia coli. In this paper, size exclusion chromatography was used to study the effect of the SulA and MinCD division inhibitors on the oligomerization state of endogenous FtsZ in cytoplasmic extracts, and immunofluorescence microscopy was used to determine the effect of SulA and MinCD on the formation of FtsZ, FtsA and ZipA rings at potential division sites. SulA prevented the formation of high-molecular-weight FtsZ polymers by interfering with FtsZ dimerization and subsequent oligomerization. In contrast, the MinCD division inhibitor did not prevent the oligomerization of FtsZ in the cell extracts or the formation of FtsZ and ZipA ring structures in vivo. However, MinCD did prevent the formation of FtsA rings. Increased expression of ftsA suppressed MinCD-induced division inhibition, but had no effect on SulA-induced division inhibition. These results indicate that MinCD blocks the assembly of the septation machinery at a later step than SulA, at the stage at which FtsA is added to the FtsZ ring.

Bacterial cell division.

Formation of the bacterial division septum is catalyzed by a number of essential proteins that assemble into a ring structure at the future division site. Assembly of proteins into the cytokinetic ring appears to occur in a hierarchial order that is initiated by the FtsZ protein, a structural and functional analog of eukaryotic tubulins. Placement of the division site at its correct location in Escherichia coli requires a division inhibitor (MinC), that is responsible for preventing septation at unwanted sites near the cell poles, and a topological specificity protein (MinE), that forms a ring at midcell and protects the midcell site from the division inhibitor. However, the mechanism responsible for identifying the position of the midcell site or the polar sites used for spore septum formation is still unclear. Regulation of the division process and its coordination with other cell cycle events, such as chromosome replication, are poorly understood. However, a protein has been identified in Caulobacter (CtrA) that regulates both the initiation of chromosome regulation and the transcription of ftsZ, and that may play an important role in the coordination process.

Form perception with a 49-point electrotactile stimulus array on the tongue: a technical note.

Form perception with the tongue was studied with a 49-point electrotactile array. Five sighted adult human subjects (3M/2F) each received 4 blocks of 12 tactile patterns, approximations of circles, squares, and vertex-up equilateral triangles, sized to 4x4, 5x5, 6x6, and 7x7 electrode arrays. Perception with electrical stimulation of the tongue is better than with fingertip electrotactile stimulation, and the tongue requires 3% (5-15 V) of the voltage. The mean current for tongue subjects was 1.612 mA. Tongue shape recognition performance across all sizes was 79.8%. The approximate dimensions of the electrotactile array and the dimensions of compartments built into dental retainers have been determined. The goal is to develop a practical, cosmetically acceptable, wireless system for blind persons, with a miniature TV camera, microelectronics, and FM transmitter built into a pair of glasses, and the electrotactile array in a dental orthodontic retainer.

Exogenous isolation of Hgr plasmids from coastal Mediterranean waters and their effect on growth and survival of Escherichia coli in sea water.

Four self-conjugative plasmids conferring mercury resistance were exogenously isolated from coastal Mediterranean sea water. All the plasmids isolated (93.2, 73.1, 65.2 and 221 kb) showed narrow-spectrum mercury resistance, and no UV resistance; three of them conferred cadmium resistance (Cdr 1.5 mM) and two of them encoded streptomycin resistance (50 micrograms/ml). Their influence on the survival of the recipient strain Escherichia coli JGL1 in different seawater media was studied and compared with that of two plasmids previously isolated by the same procedure from an epilithic community of the Bristol Channel, Great Britain. A significant negative influence was observed for the largest (221 kb) of the plasmids isolated and one of the epilithic plasmids (239 kb). The effect of the plasmids on E.coli JGL1 was dependent on the seawater media.

An extracellular factor regulates expression of sdiA, a transcriptional activator of cell division genes in Escherichia coli.

The sdiA gene codes for a protein that regulates expression of the ftsQAZ cluster of essential cell division genes of Escherichia coli. SdiA up-regulates the ftsQ2p promoter that initiates transcription into the ftsQAZ cluster. In this paper, we report that expression of sdiA is itself regulated by a factor that is released into the growth medium by E. coli. When medium that had previously supported growth of E. coli (conditioned medium) was used to support growth of an indicator E. coli strain that contained an sdiA-lacZ transcriptional reporter, there was a 50 to 80% decrease in sdiA expression as monitored by beta-galactosidase activity. The down-regulation of PsdiA was associated with a decrease in expression of the SdiA target promoter ftsQ2p, as monitored by expression of an ftsQ2p-lacZ transcriptional fusion. An effect of conditioned medium on ftsQ2p expression was not seen when the wild-type sdiA gene was disrupted by insertional mutagenesis, indicating that the effect on ftsQ2p expression was secondary to the down-regulation of PsdiA. Conditioned medium had no effect on expression of Plac, PrpoS, or several other promoters associated with the ftsQAZ gene cluster (ftsQ1p and ftsZ1-4p). This suggests that the response is specific for PsdiA and for promoters that are regulated by the sdiA gene product and that cell-to-cell signalling may play a role in regulating expression of this group of genes.

[Doppler echocardiography in endomyocardial fibrosis]. / Ecocardiografía Doppler en la fibrosis endomiocárdica.

Twelve patients with endomyocardial fibrosis with angiographic and/or histologic corroboration were studied with Doppler echocardiography with the purpose of describing the echocardiographic features and identify the affected sites. The average age was 41 years (range 16 to 59 years), 2 men and 10 women. Three patients (25%) had isolated right ventricular involvement, one patient (8%) left ventricular, 8 patients (66%) both ventricular. Our Doppler echocardiographic findings were: right atrium enlargement (91%), right ventricle outflow dilatation (83%), paradoxical septal motion (83%), left atrial enlargement (33%), mitral and tricuspid valve prolapse (50%), pericardial effusion (41%), mitral regurgitation (75%), tricuspid regurgitation (100%), apex obliteration (50%) and a restrictive type flow pattern (50%). Doppler echocardiography is a useful method for the diagnosis of endomyocardial fibrosis, the finding of normal or small ventricles associated with apex obliteration and enlarged atria, mitral or tricuspid regurgitation and a restrictive type flow pattern are characteristics of this disease. In our population, the isolated or predominantely right ventricular involvement is the most common finding as it represented 83% of the cases.

Effect of previous growth conditions on the starvation-survival of Escherichia coli in seawater.

The starvation-survival of Escherichia coli in seawater was assessed by plate and epifluorescence counts, 3H-label decrease, cellular DNA concentrations, and metabolic activities. These assays were performed on two types of populations, adapted and non-adapted to seawater. The number of viable cells in the adapted population remained constant throughout starvation-survival in sterile seawater. In contrast, a significant decrease in the ability of the non-adapted E. coli to form colonies on plates following starvation-survival in sterile seawater was observed. However, this drop in viable counts was not mirrored by the epifluorescence counts and 3H-label, which did not show major changes for either population during the experiments, indicating maintenance of the number of cells. In addition, a significant increase in and subsequent maintenance of DNA content and thymidine incorporation was observed for both populations during starvation-survival in sterile seawater. The changes in cell-attached exoproteolytic activity and electron transport system activity showed that adapted and non-adapted E. coli cells maintain their metabolic potential. Cell-free exoproteolytic activity was drastically reduced in both populations. Adapted cells showed higher electron transport system activity and thymidine incorporation than non-adapted cells at the onset of starvation-survival. The effect of previous adaptation on E. coli starvation-survival, as assessed by plate counts and 3H-label decrease, was also observed in raw seawater. It seems from these data that the biological potential of E. coli cells suspended in sterile seawater has not been switched off or impaired seriously.

Mortality of marine bacterial strains in seawater.

As an approach for assessing the dynamics of bacterial population in seawater, the survival of five isolated marine bacteria strains was assessed by the disappearance of radioactivity in the cold trichloroacetic acid (TCA)-insoluble fraction from a previously 3H-labeled culture. Metabolic activity during survival experiments was assessed by the measurement of electron transport system (ETS) activity. Fractionated filtration was used to assess the grazing mortality. The particulate fraction that passed 2.0 microns and was retained in 0.2 microns was the main cause of mortality.

Mortality of fecal bacteria in seawater.

We propose a method for determining the mortality rate for allochthonous bacteria released in aquatic environments without interference due to the loss of culturability in specific culture media. This method consists of following the disappearance of radioactivity from the trichloroacetic acid-insoluble fraction in water samples to which [3H]thymidine-prelabeled allochthonous bacteria have been added. In coastal seawater, we found that the actual rate of disappearance of fecal bacteria was 1 order of magnitude lower than the rate of loss of culturability on specific media. Minor adaptation of the procedure may facilitate assessment of the effect of protozoan grazing and bacteriophage lysis on the overall bacterial mortality rate.