Effects of sunflower oil infusions of Asparagopsis taxiformis on in vitro ruminal methane production and biohydrogenation of polyunsaturated fatty acids

Asparagopsis taxiformis inhibits ruminal methane (CH4) production due to its bromoform (CHBr3) content. The immersion of A. taxiformis in edible vegetable oils allows the extraction and stabilization of the highly volatile CHBr3 in the oil phase. The objectives of this study were to explore the effects of adding sunflower oils with increasing concentrations of CHBr3 on in vitro ruminal methanogenesis and biohydrogenation. Five batches of 48-h in vitro incubations were performed in 14 fermentation bottles, using rumen inocula collected shortly after the slaughter of young crossbred bulls and 1 g of dry matter (DM) from a total diet of mixed feed without added oil (control) or with 60 μL of sunflower oil per gram of DM as the substrate. The treatments were the CHBr3 content in the oil added: 0 μg (B0), 25 μg (B25), 50 μg (B50), 75 μg (B75), 100 μg (B100), and 150 μg (B150) of CHBr3 per gram of substrate DM. Organic matter (OM) degradability, total gas, CH4, volatile fatty acids (VFA), long-chain fatty acids, and dimethyl acetals (DMA) were analyzed at the end of each incubation. Data were analyzed with a model considering the treatments as the fixed effect and the run as a random block and using orthogonal contrasts. Degradability of OM was higher in the control group and was unaffected by CHBr3 concentration. Total gas production per gram of degraded OM was unaffected by treatments and averaged 205 ± 29.8 mL/g. Methane (mL) production decreased linearly with increasing CHBr3 concentrations, with 33%, 47%, and 87% reductions for B75, B100, and B150, respectively. Total VFA concentration was unaffected by oil inclusion but was reduced by 20% in CHBr3-containing treatments, although without any dose-response pattern. The molar percentage of acetate decreased linearly, whereas propionate and butyrate increased linearly with the increasing CHBr3 dosage. Including oil in the diet decreased the branched-chain fatty acids and DMA content. Increasing CHBr3 concentrations did not affect branched-chain fatty acids, but linearly increased most of the identified DMA. Adding oil to the control diet increased the 18:2n-6, whereas increasing the concentration of CHBr3 had no effect on 18:2n-6 but decreased linearly the 18:0 and increased the trans-18:1 isomers. The results obtained provide evidence that oil immersions of A. taxiformis can successfully inhibit ruminal production of CH4 in vitro at doses of 100 and 150 μg/g DM, and simultaneously modulate biohydrogenation.

In vitro activity of cefiderocol and other newly approved antimicrobials against multi-drug resistant Gram-negative pathogens recovered in intensive care units in Spain and Portugal

OBJECTIVE

The antimicrobial resistance is a significant public health threat, particularly for healthcare-associated infections caused by carbapenem-resistant Gram-negative pathogens which are increasingly reported worldwide. The aim of this study was to provide data on the in vitro antimicrobial activity of cefiderocol and that of commercially available comparator antibiotics against a defined collection of recent clinical multi-drug resistant (MDR) microorganisms, including carbapenem resistant Gram-negative bacteria collected from different regions in Spain and Portugal.

METHODS

A total of 477 clinical isolates of Enterobacterales, Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophilia were prospectively (n=265) and retrospectively (n=212) included (2016-2019). Susceptibility testing was performed using standard broad microdilution and results were interpreted using CLSI-2021 and EUCAST-2021 criteria.

RESULTS

Overall, cefiderocol showed a good activity against Enterobacterales isolates, being 99.5% susceptible by CLSI and 94.5% by EUCAST criteria. It also demonstrated excellent activity against P. aeruginosa and S. maltophilia isolates, all being susceptible to this compound considering CLSI breakpoints. Regarding A. baumannii (n=64), only one isolate was resistant to cefiderocol.

CONCLUSIONS

Our results are in agreement with other studies performed outside Spain and Portugal highlighting its excellent activity against MDR gram-negative bacteria. Cefiderocol is a therapeutic alternative to those available for the treatment of infections caused by these MDR bacteria.

Clinical characteristics with inflammation profiling of long COVID and association with 1-year recovery following hospitalisation in the UK: a prospective observational study

BACKGROUND

No effective pharmacological or non-pharmacological interventions exist for patients with long COVID. We aimed to describe recovery 1 year after hospital discharge for COVID-19, identify factors associated with patient-perceived recovery, and identify potential therapeutic targets by describing the underlying inflammatory profiles of the previously described recovery clusters at 5 months after hospital discharge.

METHODS

The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study recruiting adults (aged ≥18 years) discharged from hospital with COVID-19 across the UK. Recovery was assessed using patient-reported outcome measures, physical performance, and organ function at 5 months and 1 year after hospital discharge, and stratified by both patient-perceived recovery and recovery cluster. Hierarchical logistic regression modelling was performed for patient-perceived recovery at 1 year. Cluster analysis was done using the clustering large applications k-medoids approach using clinical outcomes at 5 months. Inflammatory protein profiling was analysed from plasma at the 5-month visit. This study is registered on the ISRCTN Registry, ISRCTN10980107, and recruitment is ongoing.

FINDINGS

2320 participants discharged from hospital between March 7, 2020, and April 18, 2021, were assessed at 5 months after discharge and 807 (32·7%) participants completed both the 5-month and 1-year visits. 279 (35·6%) of these 807 patients were women and 505 (64·4%) were men, with a mean age of 58·7 (SD 12·5) years, and 224 (27·8%) had received invasive mechanical ventilation (WHO class 7-9). The proportion of patients reporting full recovery was unchanged between 5 months (501 [25·5%] of 1965) and 1 year (232 [28·9%] of 804). Factors associated with being less likely to report full recovery at 1 year were female sex (odds ratio 0·68 [95% CI 0·46-0·99]), obesity (0·50 [0·34-0·74]) and invasive mechanical ventilation (0·42 [0·23-0·76]). Cluster analysis (n=1636) corroborated the previously reported four clusters: very severe, severe, moderate with cognitive impairment, and mild, relating to the severity of physical health, mental health, and cognitive impairment at 5 months. We found increased inflammatory mediators of tissue damage and repair in both the very severe and the moderate with cognitive impairment clusters compared with the mild cluster, including IL-6 concentration, which was increased in both comparisons (n=626 participants). We found a substantial deficit in median EQ-5D-5L utility index from before COVID-19 (retrospective assessment; 0·88 [IQR 0·74-1·00]), at 5 months (0·74 [0·64-0·88]) to 1 year (0·75 [0·62-0·88]), with minimal improvements across all outcome measures at 1 year after discharge in the whole cohort and within each of the four clusters.

INTERPRETATION

The sequelae of a hospital admission with COVID-19 were substantial 1 year after discharge across a range of health domains, with the minority in our cohort feeling fully recovered. Patient-perceived health-related quality of life was reduced at 1 year compared with before hospital admission. Systematic inflammation and obesity are potential treatable traits that warrant further investigation in clinical trials.

FUNDING

UK Research and Innovation and National Institute for Health Research.

Small for gestational age very preterm infants present a higher risk of developing bronchopulmonary dysplasia

INTRODUCTION

Several studies assessed the influence of a low birth weight on bronchopulmonary dysplasia (BPD), but not all could find a significant association. Our aim was to assess the association between low birth weight and BPD in preterm infants, prospectively recruited at 11 level III Portuguese neonatal centers.

METHODS

Obstetrical and neonatal data on mothers and preterm infants with gestational ages between 24 and 30 weeks, born during 2015 and 2016 after a surveilled pregnancy, were analyzed. Neonates were considered small for gestational age (SGA) when their birthweight was below the 10th centile of Fenton's growth chats and BPD was defined as the dependency for oxygen therapy until 36 weeks of corrected age. Statistical analysis was performed using IBM SPSS® statistics 23 and a p-value <0.05 was considered statistically significant.

RESULTS

Out of 614, a total of 494 preterm infants delivered from 410 women were enrolled in the study; 40 (8.0%) infants with SGA criteria. SGA were more often associated with a single pregnancy, had greater use of antenatal corticosteroids, increased prevalence of gestational hypertensive disorders, C-section, rupture of membranes below 18 hours, rate of intubation in the delivery room, use of surfactant treatment, oxygen therapy, mechanical ventilation need, BPD, cystic periventricular leukomalacia, nosocomial sepsis and pneumonia; had lower prevalence of chorioamnionitis, and lower Apgar scores. The multivariate analysis by logistic regression, adjusted for BPD risk factors revealed a significant association between SGA and BPD: OR = 5.2 [CI: 1.46-18.58]; p = 0.01.

CONCLUSION

The results of this study increase the scientific evidence that SGA is an independent risk factor for BPD.

Elucidating constraints for differentiation of major human Klebsiella pneumoniae clones using MALDI-TOF MS

The establishment of matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF MS) in routine microbial identification boosted many developments towards high-throughput applications, including bacterial typing. However, results are still controversial for different bacterial species. We aim to evaluate the suitability of MALDI-TOF MS for typing clinically relevant multidrug resistant (MDR) Klebsiella pneumoniae subsp. pneumoniae clones using routine conditions and a previously validated chemometric analysis workflow. Mass spectra of 83 K. pneumoniae clinical isolates representing major human MDR clones [11 sequence types (STs), 22 PFGE-types] recovered in Portugal and Spain during outbreaks and non-outbreak situations (2003-2012) were obtained from cell extracts (CE) and intact cells (IC), and analysed with different chemometric tools. We observed a highly consistent peak pattern among isolates from different clones either with CE or IC, suggesting a high degree of conservation of biomolecules analysed (a large part corresponding to ribosomal proteins). Moreover, the low degree of agreement between MALDI-TOF MS and other methods (from 34.9 % to 43.4 % of correct assignments for CE and from 40.8 % to 70.1 % for IC) corroborates the low discriminatory potential of the technique at infraspecies level. Our results suggest a low discriminatory power of MALDI-TOF MS for clinically relevant MDR K. pneumoniae clones and highlight the need of developing tools for high-resolution typing in this species.

MALDI-TOF mass spectrometry as a tool for the discrimination of high-risk Escherichia coli clones from phylogenetic groups B2 (ST131) and D (ST69, ST405, ST393)

Reliable, quick and low-cost methods are needed for the early detection of multidrug-resistant and highly virulent high-risk B2 and D Escherichia coli clones or clonal complexes (HiRCC). Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) seems to have a good discriminatory potential at different subspecies levels, but it was never evaluated for the discrimination of E. coli clones. We assessed the potential of MALDI-TOF MS coupled to multivariate data analysis to discriminate representative E. coli B2 and D HiRCC. Seventy-three E. coli isolates from B2 (including ST131 and B2 non-ST131 clones) and D (ST69, ST393, ST405) with variable pulsed-field gel electrophoresis (PFGE) patterns, origins and dates (1980-2010) were tested. MS spectra were acquired from independent extracts obtained from different plate cultures in two different Microflex LT MALDI-TOF devices (Bruker) after a standard extraction procedure. MALDI-TOF MS fingerprinting analysis revealed a good discriminatory ability between the four HiRCC analysed (ST131, ST69, ST405, ST393) and between B2 ST131 and other B2 non-ST131 isolates. Clusters defined by MALDI-TOF MS were consistent with the clonal complexes assigned by multilocus sequence typing (MLST), although differences were detected regarding the composition of clusters obtained by the comparison of PFGE profiles. We demonstrate, for the first time, that characteristic mass fingerprints of different E. coli HiRCC are sufficiently discriminatory and robust to enable their differentiation by MALDI-TOF MS, which might represent a promising tool for the optimisation of infection control, individual patient management and large-scale epidemiological studies of public health relevance. The good correlation between phenotypic and genotypic features further corroborates phylogenetic relationships delineated by MLST.

Rapid detection of urinary tract infections caused by Proteus spp. using PNA-FISH

We developed a fluorescence in situ hybridization (FISH) method for the rapid detection of Proteus spp. in urine, using a novel peptide nucleic acid (PNA) probe. Testing on 137 urine samples from patients with urinary tract infections has shown specificity and sensitivity values of 98 % (95 % CI, 93.2-99.7) and 100 % (95 % CI, 80,8-100), respectively, when compared with CHROMagar Orientation medium. Results indicate that PNA-FISH is a reliable alternative to traditional culture methods and can reduce the diagnosis time to approximately 2 h.

The protein information and property explorer: an easy-to-use, rich-client web application for the management and functional analysis of proteomic data

MOTIVATION

Mass spectrometry experiments in the field of proteomics produce lists containing tens to thousands of identified proteins. With the protein information and property explorer (PIPE), the biologist can acquire functional annotations for these proteins and explore the enrichment of the list, or fraction thereof, with respect to functional classes. These protein lists may be saved for access at a later time or different location. The PIPE is interoperable with the Firegoose and the Gaggle, permitting wide-ranging data exploration and analysis. The PIPE is a rich-client web application which uses AJAX capabilities provided by the Google Web Toolkit, and server-side data storage using Hibernate.

AVAILABILITY

http://pipe.systemsbiology.net.

Multicentre evaluation of the VITEK 2 Advanced Expert System for interpretive reading of antimicrobial resistance tests

Interpretive reading analyses the complete resistance profiles of bacteria to multiple antibiotics and infers the resistance mechanisms present; it aids therapeutic choice and enhances surveillance data. We evaluated the Advanced Expert System (AES), which interprets MICs generated by the VITEK 2. Ten European laboratories tested 42 reference strains and 76-106 of their own strains, representing important resistance genotypes. Interpretive reading by the VITEK 2 AES achieved full agreement with genotype data for 88-89% of strains, with the correct mechanism identified as one of two possibilities for a further 5-6%. Mechanisms inferred with 90% agreement with reference data included methicillin resistance in staphylococci, glycopeptide resistance in enterococci, quinolone resistance in staphylococci and Enterobacteriaceae, AAC(6')-APH(2")-mediated aminoglycoside resistance in Gram-positive cocci, erm-mediated macrolide resistance in pneumococci, extended-spectrum beta-lactamases (ESBLs) in Enterobacteriaceae and Pseudomonas aeruginosa, and acquired penicillinases in Enterobacteriaceae. VanA, VanB and VanC phenotypes of enterococci were distinguished reliably, and ESBL production was accurately inferred in AmpC-inducible species as well as Escherichia coli and Klebsiella spp. Mechanisms identified, but only as possibilities among several, included IRT-type beta-lactamases and individual aminoglycoside-modifying enzymes in Enterobacteriaceae. Most disagreements with reference data concerned pneumococci found to have high-level penicillin resistance by the VITEK 2 AES but previously determined, phenotypically, to have intermediate resistance. When ESBL production was inferred in E. coli and klebsiellae, the VITEK 2 AES edited susceptible results for cephalosporins (except cefoxitin) to resistant; when an acquired penicillinase was inferred in Enterobacteriaceae, piperacillin results were edited to resistant; and when staphylococci were found methicillin resistant, resistance was reported for all beta-lactams. Further editing may be desirable (e.g. of cephalosporin results for salmonellas inferred to have ESBLs).

Amphotericin B kills unicellular leishmanias by forming aqueous pores permeable to small cations and anions

The polyene antibiotic amphotericin B (AmB) is known to form two types of ionic channels across sterol-containing liposomes, depending on its concentration and time after mixing (Cohen, 1992). In the present study, it is shown that AmB only kills unicellular Leishmania promastigotes (LPs) when aqueous pores permeable to small cations and anions are formed. Changes of membrane potential across ergosterol-containing liposomes and LPs were followed by fluorescence changes of 3,3' dipropylthiadicarbocyanine (DiSC3(5)). In KCl-loaded liposomes suspended in an iso-osmotic sucrose solution, low AmB concentrations (</=0.1 microM) induced a polarization potential, indicating K+ leakage, but no movement of cations and anions was allowed until AmB concentrations greater than 0.1 microM were added. In agreement with these data, it was found that AmB altered the negative membrane potential held across LPs in a manner consistent with the differential cation/anion selectivity exhibited by the channels formed in liposomes. Thus, LPs suspended in an iso-osmotic sucrose solution did not exhibit any AmB-induced membrane depolarization effect brought about by efflux of anions until 0.1 microM or higher AmB concentrations were added. By contrast, LPs suspended in an iso-osmotic NaCl solution and exposed to 0.05 microM AmB exhibited a nearly total collapse of the negative membrane potential, indicating Na+ entry into the cells. The concentration dependence of the AmB-induced permeability to different salts was also measured across vesicles derived from the plasma membrane of leishmanias (LMVs), by using a rapid mixing technique. At concentrations above 0.1 microM, AmB induced the formation of aqueous pores across LMVs with a positive cooperativity, yielding Hill coefficients between 2 to 3. Measured anion selectivity across such aqueous pores followed the sequence: SCN > NO3 > Cl > I > Br > acetate (SO2-4 being impermeable). Cell killing by AmB was followed by fluorescence changes of the DNA-binding compound ethidium bromide (EB). At low concentrations (</=0.1 microM), AmB was found to be nonlethal against LPs but, above this concentration, leishmanias were rapidly killed. The rate and extent of such an effect were found to be dependent on the type of cation and anion present in the external aqueous solution. For both NH+4 and Na+ salts, the measured rank order of AmB cell killing followed the same sequence that was determined for AmB-induced salt permeation across LMVs. Further, replacement of either extracellular Na+ by choline or Cl- by SO2-4, or its partial substitution by sucrose, in iso-osmotic conditions, led to a complete inhibition of the killing effect exerted by otherwise lethal AmB concentrations. Finally, it was shown that tetraethylammonium (TEA+), an organic cation that is known to block AmB-induced salt permeation across LMVs was able to retard the time lag observed for EB incorporation across LPs, indicating that this parameter can be taken to represent the time taken for salt accumulation inside the parasites. The present results thus indicate clearly that low AmB concentrations (</=0.1 microM) were able to form across LPs, cation channels that collapsed the parasite membrane potential but are not lytic. At high concentrations (>/=0.1 microM), a salt influx via the aqueous pores formed by the antibiotic was followed by osmotic changes leading to cell lysis. This last stage is supported by electron microscopy observations of the changes of parasite morphology immediately upon addition of AmB, which indicated that the typical elongated promastigote cell forms became rounded and the flagella swells and round up. The present work is the first demonstration of the in vitro sensitivity of Leishmania promastigotes to osmotic lysis by AmB.

Structural integrity and identification of causes of liver allograft dysfunction occurring more than 5 years after transplantation

The clinicopathologic features of liver allograft dysfunction occurring in 51 symptomatic recipients after more than 5 years' survival (mean 7.1 years) with the same hepatic allograft were compared with those of a similar group of 14 asymptomatic patients (mean survival, 9.9 years) who underwent a nonclinically indicated protocol liver biopsy evaluation. Predictably, patients who had clinically indicated biopsies more frequently showed histopathologic alterations (76% versus 36%, p < 0.002). After detailed clinicopathologic correlation, the changes in the symptomatic patients were attributed primarily to definite or presumed viral hepatitis in 17 of 51 (33%) patients, 11 of whom had recurrent viral disease; seven of 51 (14%) had nonviral recurrent original disease, three (6%) had obstructive cholangiopathy, and 11 (22%) had acute and/or chronic rejection. In 13 of 51 (25%) of the symptomatic patients, the clinical and pathologic abnormalities were minimal. Long-term liver allograft survival in nine of 14 (64%) of the asymptomatic patients was associated with minimally abnormal histologic alterations. Two of the asymptomatic patients had obstructive cholangiopathy; two others has recurrence of the original disease and one has possible viral hepatitis. Viral hepatitis types B and C, alcoholic liver disease, autoimmune hepatitis, granulomatous hepatitis (not otherwise specified), and probably primary biliary cirrhosis and primary sclerosing cholangitis were shown to recur after hepatic transplantation. The histopathologic changes associated with acute and chronic rejection frequently overlapped with other syndromes causing late dysfunction, such as chronic viral or autoimmune hepatitis, primary biliary cirrhosis, or primary sclerosing cholangitis; more than one insult could be identified in 15 cases, which made the differential diagnosis of causes of late liver allograft dysfunction much more difficult than early after hepatic transplantation. It is important to correlate the biopsy findings with the liver injury tests, the results of viral and autoimmune antibody serologic studies, and review of previous biopsies and to be aware of the original disease, recent changes in immunosuppression, and results of therapeutic intervention(s) to identify correctly the causes of liver allograft dysfunction in this patient population.

Early tolerance in pediatric liver allograft recipients

The authors report on six pediatric liver transplant recipients for whom allograft tolerance occurred shortly after transplantation (ie, less than 1.5 years). All the patients had associated life-threatening viral complications. They are currently immunocompetent. The tolerant state may be related to the development of a TH2 cytokine pattern.

Effect of ketoconazole on lethal action of amphotericin B on Leishmania mexicana promastigotes

The effect of ergosterol depletion by ketoconazole on the leishmanicidal activity of the pore-forming antibiotic amphotericin B (AmB) was investigated. Leishmania mexicana promastigotes were lysed within minutes by the addition of micromolar concentrations of AmB (0.5 microM) but became insensitive to AmB after growth in the presence of ketoconazole (0.25 microM, 90 h). Lipid chromatographic analysis indicated that under such conditions, ketoconazole depleted the major Leishmania sterols, dehydroepisterol and ergosterol. Plasma membrane vesicles prepared from ketoconazole-treated promastigotes exhibited a much reduced enhancement of their salt permeability after the addition of AmB at concentrations as high as 5 microM. This finding clearly indicates that upon ketoconazole treatment, the capacity of pore formation by the antibiotic is substantially impaired. The reduction of desmethyl sterols by ketoconazole was accompanied by a significant increase of 14-alpha-methyl sterols, but exogenous cholesterol remained unchanged. This ability of Leishmania promastigotes to incorporate cholesterol from the external medium may explain why ketoconazole-treated cells exhibited a much decreased but significative response to AmB when they were exposed to high AmB concentrations (2.5 or 5.0 microM). Parallel measurements by using a fluorescence energy transfer method indicated that binding of AmB to ketoconazole-treated Leishmania promastigotes and heat-transformed leishmanias was also decreased but to different extents, a finding that may be related to the differences in their sterol content. The results obtained clearly indicate that the specific interaction of AmB with desmethyl sterols, such as dehydroepisterol, ergosterol, and even exogenous cholesterol, is an absolute requirement for the lethal action exerted by this polyene antibiotic on L. mexicana promastigotes.

Combined liver-kidney transplantation and the effect of preformed lymphocytotoxic antibodies

Thirty-eight sequentially placed liver and kidney allografts were evaluated with respect to patient and graft survival, and the influence of preformed lymphocytotoxic antibodies was analysed. The results suggest that the survival rate of combined liver and kidney transplantation is similar to the survival rate of liver transplantation alone. Sequentially placed kidney allografts may be protected from hyperacute rejection in the presence of donor specific lymphocytotoxic antibodies, but not in all instances. Both patient and kidney allograft survival was lower in positive crossmatch patients (33% and 17% respectively) than in negative crossmatch patients (78% and 75%). High levels of panel reactive antibodies (> 10%) also appeared to have a deleterious effect on survival, although the majority of the patients who failed also had a positive crossmatch. Although performed lymphocytotoxic antibodies are not an absolute contraindication to combined liver-kidney transplantation, they do appear to have a deleterious effect on long-term graft survival. However, more correlation with clinical parameters is needed.

Cell migration and chimerism after whole-organ transplantation: the basis of graft acceptance

Improvements in the prevention or control of rejection of the kidney and liver have been largely interchangeable (1 , 2 ) and then applicable, with very little modification, to thoracic and other organs. However, the mechanism by which anti rejection treatment permits any of these grafts to be “accepted” has been an immunological enigma (3 , 4 ). We have proposed recently that the exchange of migratory leukocytes between the transplant and the recipient with consequent long-term cellular chimerism in both is the basis for acceptance of all whole-organ allografts and xenografts (5 ). Although such chimerism was demonstrated only a few months ago, the observations have increased our insight into transplantation immunology and have encouraged the development of alternative therapeutic strategies (6 ).

Chimerism and donor-specific nonreactivity 27 to 29 years after kidney allotransplantation

Chimerism was demonstrated with immunocytochemical and/or polymerase chain reaction techniques in kidney allografts and in the native skin, lymph nodes, or blood of 5 of 5 patients who received continuously functioning renal transplants from 1 or 2 haplotype HLA mismatched consanguineous donors (4 parents, 1 aunt) 27-29 years ago. In the 4 cases where the kidney donor still was alive to provide stimulator lymphocytes for testing, these provoked no (n = 2) or modest (n = 2) MLR in contrast to vigorous MLR to third party lymphocytes. In all 4 cases, the donor cells failed to generate in vitro cytotoxic effector cells (cell-mediated lymphocytotoxicity). These findings are in accord with the hypothesis that cell migration, repopulation, and chimerism are seminal events that define graft acceptance and ultimately can lead to acquired donor-specific nonresponsiveness (tolerance).

Cell migration and chimerism after whole-organ transplantation: the basis of graft acceptance

Improvements in the prevention or control of rejection of the kidney and liver have been largely interchangeable (1, 2) and then applicable, with very little modification, to thoracic and other organs. However, the mechanism by which anti rejection treatment permits any of these grafts to be “accepted” has been an immunological enigma (3, 4). We have proposed recently that the exchange of migratory leukocytes between the transplant and the recipient with consequent long-term cellular chimerism in both is the basis for acceptance of all whole-organ allografts and xenografts (5). Although such chimerism was demonstrated only a few months ago, the observations have increased our insight into transplantation immunology and have encouraged the development of alternative therapeutic strategies (6).

Recent advances in hepatic transplantation at the University of Pittsburgh

FK506 undoubtedly improved the survival advantage of hepatic allotransplantation. Hepatic-intestinal and multivisceral transplantation has also become a feasible therapy for patients with combined intestinal and liver failure. With better understanding of the immunologic and metabolic aspects of allo- and xenotransplantation, further clinical attempts to transplant animal organs to humans may be considered with the hope for a better outcome in the very near future.

Systemic chimerism in human female recipients of male livers

We have previously reported data from clinical and laboratory animal observations which suggest that organ tolerance after transplantation depends on a state of balanced lymphodendritic cell chimerism between the host and donor graft. We have sought further evidence to support this hypothesis by investigating HLA-mismatched liver allograft recipients. 9 of 9 female recipients of livers from male donors had chimerism in their allografts and extrahepatic tissues, according to in-situ hybridisation and molecular techniques 10 to 19 years posttransplantation. In 8 women with good graft function, evidence of the Y chromosome was found in the blood (6/8), skin (8/8), and lymph nodes (7/8). A ninth patient whose transplant failed after 12 years from recurrent chronic viral hepatitis had chimerism in her lymph nodes, skin, jejunum, and aorta at the time of retransplantation. Although cell migration is thought to take place after all types of transplantation, the large population of migratory cells in, and the extent of their seeding from, hepatic grafts may explain the privileged tolerogenicity of the liver compared with other organs.

[The Mexico of "the other side": Mexican immigrants in the United States]

"The purpose of this work is to explore the advantages and disadvantages of... Mexican immigrant workers for the economy and the political and cultural status quo of the United States. The Mexican immigrant workers pose a dilemma for the United States. On the one hand, the United States needs them for a better functioning of its economy. On the other, the Mexican immigrant workers represent a racial, cultural and political challenge to the American 'establishment'.... Given the magnitude of the problem which the Mexican immigrants represent and the intense debate surrounding it, the cheap labour they represent for the economy of the United States and the unsolved conflicts this provokes, are fertile ground for the analysis of the economic, political and cultural interests competing for the degree of flexibility or the amount of policing the Mexican border should have." (SUMMARY IN ENG AND FRE)

Enhanced action of amphotericin B on Leishmania mexicana resulting from heat transformation

A comparative study of the effect of the polyene antibiotic amphotericin B (AmB) on the viability of Leishmania mexicana promastigotes before and after their transformation by heat into amastigotelike forms was carried out. The kinetics of cell death were followed by spectrofluorometry with the nucleic acid-binding compound ethidium bromide. It was found that the rapid killing effect that is exerted by AmB on Leishmania promastigotes was even faster after their transformation into amastigotelike forms. Binding studies of AmB to Leishmania membranes by circular dichroism indicated that heat transformation modified it from noncooperative to cooperative binding, decreasing the amount of antibiotic that bound to the membranes. Thus, the increased rate of ethidium bromide incorporation into transformed cells was not related either to the amount of AmB bound or to an increased amount of ergosterol in the membrane (the ergosterol/phospholipid ratio was four times smaller after heat shock). An increase in the Mg2+ content of the external aqueous solution was able to prevent the AmB-induced incorporation of ethidium bromide into Leishmania promastigotes to a greater extent (Ki = 13.8 mM) than it was into heat-transformed cells (Ki = 64 mM), suggesting that there were significant changes at the Leishmania cell surface on heat transformation. The significance of these results for understanding the mechanism of action of AmB on sensitive organisms is discussed.

The polyene antibiotic amphotericin B acts as a Ca2+ ionophore in sterol-containing liposomes

Amphotericin B (AmB) was shown to induce a Ca2+ influx across ergosterol- and cholesterol-containing large unilamellar liposomes, by following spectrophotometrically the formation of the Arsenazo III-Ca2+ complex. At equivalent antibiotic concentrations the Ca2+ influx was much more extensive through ergosterol-containing membranes (almost 100% with 1 microM AmB, 160 microM lipid) than through cholesterol-containing membranes (below 0.5 microM the influx of Ca2+ was negligible). In the presence of ergosterol-containing membranes the initial rate of Ca2+ influx had the same linear dependence on the ratio antibiotic/lipid whatever the lipid concentration, which was not the case in cholesterol-containing membranes. These results suggest that the channels responsible for the AmB-induced Ca2+ permeability across cholesterol- and ergosterol-containing liposomes have different structures.

[Intraoperative radiotherapy in locally advanced carcinoma of the kidney: initial experience]

Intraoperative radiotherapy (IORT) is a rather interesting therapeutic modality in multidisciplinary oncology. Its greatest advantages reside in the approach of deeply seeded abdomino-pelvic tumors. Its inclusion in the therapeutic approach of renal carcinoma with a high local relapse rate has been analyzed in this study in relation to its technical aspects and preliminary clinical results. 11 stage III or IV patients or with local relapse in lumbar fossa were treated with nephrectomy or exeresis surgery and OIRT (10-20 Gy). Surgical exposure of the lumbar fossa and nodal drainage areas was appropriate in dal cases. No toxic signs or sequellae relating to OIRT were observed. Local tumor controls at 8 months of follow-up on the average (range from 2 to 33 months), was 82%. The data obtained in this series suggest the viability of the combined approach nephrectomy or rescue surgery and IORT. The initial clinical results suggest HIGH local tumor control without an increase in the toxicity rate or complications.