Mesenchymal stromal cells enhance the engraftment of hematopoietic stem cells in an autologous mouse transplantation model

Introduction

Studies have proposed that mesenchymal stem cells (MSCs) improve the hematopoietic engraftment in allogeneic or xenogeneic transplants and this is probably due to the MSCs’ immunosuppressive properties. Our study aimed to discern, for the first time, whether MSC infusion could facilitate the engraftment of hematopoietic stem cells (HSCs) in autologous transplantations models, where no immune rejection of donor HSCs is expected.

Methods

Recipient mice (CD45.2) mice, conditioned with moderate doses of radiation (5-7 Gy), were transplanted with low numbers of HSCs (CD45.1/CD45.2) either as a sole population or co-infused with increasing numbers of adipose-derived-MSCs (Ad-MSCs). The influence of Ad-MSC infusion on the short-term and long-term engraftment of donor HSCs was investigated. Additionally, homing assays and studies related with the administration route and with the Ad-MSC/HSC interaction were conducted.

Results

Our data show that the co-infusion of Ad-MSCs with low numbers of purified HSCs significantly improves the short-term and long-term hematopoietic reconstitution of recipients conditioned with moderate irradiation doses. This effect was Ad-MSC dose-dependent and associated with an increased homing of transplanted HSCs in recipients’ bone marrow. In vivo and in vitro experiments also indicate that the Ad-MSC effects observed in this autologous transplant model are not due to paracrine effects but rather are related to Ad-MSC and HSC interactions, allowing us to propose that Ad-MSCs may act as HSC carriers, facilitating the migration and homing of the HSCs to recipient bone marrow niches.

Conclusion

Our results demonstrate that Ad-MSCs facilitate the engraftment of purified HSCs in an autologous mouse transplantation model, opening new perspectives in the application of Ad-MSCs in autologous transplants, including HSC gene therapy.

Nitric oxide, derived from inducible nitric oxide synthase, decreases hypoxia inducible factor-1alpha in macrophages during aspirin-induced mesenteric inflammation

BACKGROUND AND PURPOSE

Nitric oxide (NO) modulates expression of hypoxia inducible factor-1 (HIF-1), a transcription factor regulating function of myeloid cells. Here, we have assessed the role played by NO, formed by inducible NOS (iNOS), in the inflammation induced by aspirin in the gut, by modulating HIF-1 activity.

EXPERIMENTAL APPROACH

The role of iNOS-derived NO on leucocyte-endothelial interactions induced by aspirin was evaluated by intravital microscopy in mesenteric venules of rats pretreated with selective iNOS inhibitors, 1400W or l-N6-(1-iminoethyl)-lysine. NO was localized by fluorescence microscopy, using DAF-FM. iNOS, HIF-1alpha and CD36 were localized by immunohistochemistry.

KEY RESULTS

Leucocyte-endothelial interactions increased at 6 h and returned to normal levels 24 h after aspirin administration. Numbers of migrated leucocytes were similar between 6 and 24 h after aspirin. iNOS expression and iNOS-derived NO synthesis were observed in leucocytes of the mesentery of aspirin-treated rats. Blockade of iNOS activity in aspirin-treated rats: (i) did not modify leucocyte infiltration at 6 h, but reduced the number of polymorphonuclear leucocyte and increased that of macrophages at 24 h; (ii) increased HIF-1alpha immunostaining in macrophages of the mesentery; and (iii) prevented the decrease in CD36 immunostaining induced by aspirin in these cells.

CONCLUSIONS AND IMPLICATIONS

NO, associated with acute gut inflammation induced by aspirin, diminished HIF-1alpha stabilization in macrophages. Early inhibition of iNOS-derived NO synthesis, by increasing the activity of HIF-1 in these cells, may accelerate the clearance of leucocytes.

Immunophenotypical characterization in Andalusian horse: variations with age and gender

Assessment of lymphocyte subsets is an effective method for characterizing disorders such as leukemia, lymphomas, autoimmune and infectious diseases. In order to clinically interpret these parameters, normal reference values should be set, estimating age- and gender-related variations. This research aimed to: (1) characterize lymphocyte subpopulations in Andalusian horse, and (2) evaluate age and gender-related variations of lymphocyte subsets. Jugular blood samples were obtained from 159 animals, 77 males and 82 females, belonging to four age groups-1: 1-2 years (N=39; 21 males and 18 females), 2: 2-3 years (N=38; 16 males and 22 females), 3: 3-4 years (N=41; 19 males and 22 females) and 4: 4-7 years (N=41; 21 males and 20 females). T lymphocytes subsets were quantified by flow cytometry with monoclonal antibodies specific for CD2, CD4 and CD8 cell markers. B and NK cell counts were estimated by using a mathematical formula. No variations were found in T, B lymphocytes and NK cells between males and females. Animals of group 1 and 2 had a higher number of CD2, T, CD4+, CD8+, B lymphocytes and NK cells than animals of groups 3 and 4. The percentage of CD2 in group 1 was significantly lower than in group 4. The percentage of T and CD4+ lymphocytes in the group 1 were significantly higher than groups 2 and 3, respectively. Whereas the percentage of B cells calculated by flow cytometry was significantly lower in group 2 compared to group 4, the percentage of B cells calculated by a mathematical formula was higher in group 1. NK cells percentage was significantly lower in group 3 and 4 than in younger animals. In conclusion, in Andalusian horse, gender does not influence absolute numbers and percentages of T, B and NK. There is an age-related decline in absolute number of CD2, T, CD4+ and CD8+ lymphocytes, B lymphocytes and NK cells, with increasing percentage of CD2, T, CD4+ and B lymphocytes, and a decrease in NK with no differences in CD4/CD8 ratio. The decline of lymphocyte population numbers with age is a natural process in many animal species, and could be the origin for immune dysfunction observed in geriatric individuals.

A method to establish the relationship between chronological age and stage of union from radiographic assessment of epiphyseal fusion at the knee: an Irish population study

Characteristic changes during epiphyseal union provide a skeletal age, which when compared with age-based standards provides an estimation of chronological age. Currently there are no data on epiphyseal union for the purposes of age estimation specific to an Irish population. This cross-sectional study aims to investigate the relationship between stage of epiphyseal union at the knee joint and chronological age in a modern Irish population. A novel radiographic method that sub-divides the continuum of development into five specific stages of union is presented. Anteroposterior and lateral knee radiographs of 148 males and 86 females, aged 9-19 years, were examined. Fusion was scored as Stage 0, non-union; Stage 1, beginning union; Stage 2, active union; Stage 3, recent union; or Stage 4, complete union. Stage of epiphyseal union is correlated with chronological age in both males and females. Mean age gradually increases with each stage of union and also varies between male and female subjects. A statistically significant difference in mean age was recorded between stages when compared to the previous stage, for the three epiphyses. Irish children are comparable to those from previously published studies with epiphyseal union in females occurring earlier than males. A significant difference was noted between the mean age of union for males and females for each of Stages 1 and 2 for the femur and Stages 0, 1, 2 and 3 for the tibia and the fibula. The results also suggest that the stages of union occur at earlier ages in this Irish population. Implementation of standardized methodology is necessary to investigate if this is due to a secular or population variation in maturation or to a methodology which clearly identifies five stages of union.

Inhibitory effects of N-acetylcysteine on the functional responses of human eosinophils in vitro

BACKGROUND

Oxidative stress appears to be relevant in the pathogenesis of inflammation in allergic diseases like bronchial asthma. Eosinophils are oxidant-sensitive cells considered as key effectors in allergic inflammation.

OBJECTIVE

The aim of this work was to study the effects of the clinically used antioxidant N-acetyl-L-cysteine (NAC) on the functional responses of human-isolated eosinophils.

METHODS

Human eosinophils were purified from the blood of healthy donors by a magnetic bead separation system. The effects of NAC were investigated on the generation of reactive oxygen species (chemiluminescence and flow cytometry), Ca(2+) signal (fluorimetry), intracellular glutathione (GSH; flow cytometry), p47(phox)-p67(phox) translocation (Western blot) and eosinophil cationic protein (ECP) release (radioimmunoassay).

RESULTS

NAC (0.1-1 mm) inhibited the extracellular generation of oxygen species induced by N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) and eotaxin (in the presence of IL-5) with -logIC(50) values of 3.61+/-0.03 and 3.36+/-0.09, respectively. Also, the intracellular generation of hydrogen peroxide was virtually abolished by NAC (0.5-1 mm). NAC (1 mm) did not alter the fMLP-induced Ca(2+) signal but augmented the eosinophil content of reduced GSH and inhibited p47(phox)-p67(phox) translocation. NAC inhibited the release of ECP ( approximately 90% inhibition at 1 mm) from fMLP-activated eosinophils.

CONCLUSION

Inhibition by NAC of human eosinophil functions in vitro is potentially useful in the treatment of allergic inflammation.

A halocin acting on Na+/H+ exchanger of haloarchaea as a new type of inhibitor in NHE of mammals

The capability of halocin H6 (a bacteriocin-like protein produced by haloarchaea Haloferax gibbonsii) to inhibit Na+/H+ exchanger (NHE) in mammalian cells and its cardio-protective efficacy on the ischemic and reperfused myocardium were evaluated in the present study. H6 inhibits NHE activity (measured by a flow cytometry method) in a dose-dependent form of cell lines of mammalian origin (HEK293, NIH3T3, Jurkat and HL-1) as well as in primary cell culture from human skeletal muscle (myocytes and fibroblasts). In vivo, an ischemia-reperfusion model in dogs by coronary arterial occlusion was used (two hours of regional ischemia and three hours of reperfusion). In animals treated with halocin H6 there was a significant reduction of premature ventricular ectopic beats and infarct size, whereas blood pressure and heart rate remained unchanged. Up to date, halocin H6 is the only described biological molecule that exerts a specific inhibitory activity in NHE of eukaryotic cells.

Chromosomal variation and genome size support existence of cryptic species of Triatoma dimidiata with different epidemiological importance as Chagas disease vectors

The wide geographical distribution of Triatoma dimidiata, one of the three major vectors of Chagas disease, ranges from Mexico to northern Peru. Since this species occupies a great diversity of artificial and natural ecotopes, its eradication is extremely difficult. In order to assist control efforts, we used chromosome analyses and DNA amount as taxonomic markers to study genetic variability in populations of T. dimidiata from Mexico, Guatemala, El Salvador and Colombia. We differentiated three groups or cytotypes defined by characteristic chromosome C-banding patterns and genome size measured by flow cytometry. The three cytotypes are restricted to different geographic locations. Cytotype 1 occurs in Mexico (excluding Yucatán), Guatemala (excluding Petén), El Salvador and Colombia. Cytotype 2 occurs in Yucatán and cytotype 3 occurs in Petén. Cytotype 1, commonly associated with domestic and peridomestic environments but also inhabiting sylvatic ecotopes, is the most widespread and with major epidemiological significance. In contrast, the Yucatán cytotype inhabits wild ecotopes but increasingly enters houses, while the Petén cytotype appears exclusively sylvatic. We suggest that these cytotypes represent cryptic species of T. dimidiata with different epidemiological relevance as Chagas disease vectors. Poor ability to colonize human dwellings, together with their restricted geographic distribution, indicate that the Yucatán and Petén putative species probably have much less epidemiological significance than cytotype 1. Thus, the genetic markers we describe are powerful tools to differentiate cryptic species in T. dimidiata with different epidemiological significance, contributing to planning the most effective control measures.

Eosinophil-selective mediators in human strongyloidiasis

Strongyloides stercoralis infection is characterized by the production of IgE and eosinophils in peripheral blood. Experimental studies have demonstrated that eosinophils play an important role in protection against Strongyloides stercoralis, but the mechanisms regulating eosinophils are not known. In this study we have focused on analysing the molecules that selectively regulate eosinophil migration, namely eotaxin and interleukin-5 (IL-5), using an enzyme-linked immunosorbent assay in patients with strongyloidiasis. Serum expression of eotaxin and IL-5 were significantly increased in patients compared with the control group. This rise suggests that selective mediators of the eosinophil can have a role in immunity against S. stercoralis in human infection.

Toll-like receptor 4 defective mice carrying point or null mutations do not show increased susceptibility to Candida albicans in a model of hematogenously disseminated infection

We have studied the role of TLR4 in murine defenses against Candida albicans in two TLR4-defective mouse strains: C3H/HeJ mice which have defective TLR4 signaling, and TLR4-/- knockout mice. Both TLR4-defective mice strains experimentally infected with virulent C. albicans cells showed no significant difference in survival as compared with their respective controls. Recruitment of neutrophils to the peritoneal cavity of i.p. infected mice was not affected in TLR4-/-animals, but significantly enhanced in C3H/HeJ mice, compared with their control mice. In vitro production of TNF-alpha by macrophages from both types of TLR4-defective mice, in response to yeasts and hyphae of C. albicans, was not diminished as compared with production by macrophages from wild-type mice. In vitro production of TNF-alpha by yeast-stimulated splenocytes from mice intravenously infected with the low-virulence C. albicans PCA2 strain was not affected in TLR4-defective mice, but the TNF-alpha production in response to hyphae was higher in TLR4-defective than in control animals; the production of IFN-gamma by these splenocytes was similar to controls, as well as the frequency of IFN-gamma-producing CD4+T lymphocytes, indicating that TLR4-defective mice are capable of mounting a Th1 adaptive immune response. Our data indicate that TLR4 is dispensable for murine immune resistance to C. albicans.

Origin and phylogeography of the Chagas disease main vector Triatoma infestans based on nuclear rDNA sequences and genome size

For about half of all Chagas disease cases T. infestans has been the responsible vector. Contributing to its genetic knowledge will increase our understanding of the capacity of geographic expansion and domiciliation of triatomines. Populations of all infestans subcomplex species, T. infestans, T. delpontei, T. platensis and T. melanosoma and the so-called T. infestans "dark morph", from many South American countries were studied. A total of 10 and 7 different ITS-2 and ITS-1 haplotypes, respectively, were found. The total intraspecific ITS-2 nucleotide variability detected in T. infestans is the highest hitherto known in triatomines. ITS-1 minisatellites, detected for the first time in triatomines, proved to be homologous and thus become useful markers. Calculations show that ITS-1 evolves 1.12-2.60 times faster than ITS-2. Despite all species analyzed presenting the same n=22 chromosome number, a large variation of the haploid DNA content was found, including a strikingly high DNA content difference between Andean and non-Andean specimens of T. infestans (mean reduction of 30%, with a maximum of up to 40%) and a correlation between presence/absence of minisatellites and larger/smaller genome size. Population genetics analysis of the eight composite haplotypes of T. infestans and net differences corroborate that there are clear differences between western and eastern populations (60%), and little genetic variation among populations (1.3%) and within populations (40%) within these two groups with migration rates larger than one individual per generation corresponding only to pairs of populations one from each of these groups. These values are indicative either of a large enough gene flow to prevent population differentiation by drift within each geographic area or a very recent spread, the latter hypothesis fitting available data better. Phylogenetic trees support a common ancestor for T. infestans and T. platensis, an origin of T. infestans in Bolivian highlands and two different dispersal lines, one throughout Andean regions of Bolivia and Peru and another in non-Andean lowlands of Chile, Paraguay, Argentina, Uruguay and Brazil.

Effects of the cryopreservation procedures on recovered rice cell populations

Cryogenic storage of plant cells allows the long-term maintenance of valuable genotypes. Cryopreservation of calli and cell suspensions is often performed using cryoprotectants and slow cooling rates. Rice calli (Oryza sativa L.) were cryopreserved by this procedure as well as by direct immersion in liquid nitrogen without cryoprotection. Subsequently, the characteristics of the recovered cells as well as the effects of putative cryoselection were investigated by microscopic observations and flow cytometric analyses. For this purpose, protoplasts were prepared from calli that had been cryopreserved by direct plunging into liquid nitrogen and from their unfrozen controls. Results show that direct immersion in liquid nitrogen of calli pre-treated with abscisic acid is a fast and highly efficient freezing procedure that maintains the main characteristics of the cell populations and appears to increase their metabolic activity

Expression, production, and secretion of vascular endothelial growth factor and interleukin-6 by granulosa cells is comparable in women with and without endometriosis

OBJECTIVE

To investigate the production and secretion of interleukin (IL)-6 and vascular endothelial growth factor (VEGF) mRNA and protein by granulosa luteal cells (GCs) in vivo and in vitro in women with and without endometriosis.

DESIGN

Prospective study.

SETTING

A private, university-affiliated assisted reproduction unit and a university center.

PATIENT(S)

Women with severe endometriosis (n = 6) or without the disease (n = 14) after laparoscopy, undergoing in vitro fertilization/intracytoplasmic sperm injection and embryo transfer.

INTERVENTION(S)

GCs were obtained from each aspirate.

MAIN OUTCOME MEASURE(S)

Intracellular and secreted protein, as well as mRNA for both VEGF and IL-6 in GCs.

RESULT(S)

The expression of VEGF and IL-6 mRNAs in vivo and in vitro was similar in both groups. Also, GCs from patients with endometriosis produced and secreted equal amounts of these proteins compared with controls without the disease, either in freshly isolated cells or in 24-hour cultures.

CONCLUSION(S)

The GC function in terms of VEGF and IL-6 production does not seem to be altered in patients with endometriosis in comparison with those without this condition.

Use of flow cytometry and confocal microscopy techniques to investigate early CdCl(2)-induced nephrotoxicity in vitro

CdCl(2) is a well-known toxic compound for the kidney in vivo and in vitro. We report here part of the results of an ECVAM (European Centre for the Validation of Alternative Methods) contract study, aimed at establishing and assessing several flow cytometric and confocal microscopic endpoints for use in an in vitro nephrotoxicity model. Three renal tubule cell lines, OK (opossum, proximal tubule origin), LLC-PK1 (pig, proximal tubule origin) and MDCK (dog, distal tubule origin) were exposed for 1, 5 and 24 h to 25 microM and 100 microM CdCl(2). The results obtained for mitochondrial membrane potential showed a decrease in all the cell lines after 5 h of treatment with both CdCl(2) concentrations. In some cases, this decrease was detected by flow cytometry after a 1-h exposure. On the contrary, intracellular Ca(2+) increased in a time-dependent and concentration-dependent fashion. This increase was especially high in the MDCK cell line after a 24-h exposure to 100 microM CdCl(2). However, cell viability was not affected by 25 microM CdCl(2). Our results demonstrate early changes in mitochondrial membrane potential and cytoplasmic Ca(2+) levels in renal tubular epithelial cell lines treated with CdCl(2).

Flow cytometric analysis of chronic and acute toxicity of copper(II) on the marine dinoflagellate Amphidinium carterae

BACKGROUND

Copper(II) is a heavy metal whose levels have increased in some marine ecosystems to polluting levels. Dinoflagellates, an important phytoplankton group, are at the base of aquatic food chains and bioaccumulation of copper by these microorganisms can result in complex ecosystem alterations, so we investigated how copper disturbs those cells.

METHODS

Cytotoxic effects of sublethal and lethal copper concentrations ranging from 4.2 nM (control condition) to 3.13 microM estimated labile copper were studied in batch cultures of Amphidinium carterae. Cell morphology, motility, autofluorescence, and fluorescein diacetate (FDA)-dependent fluorescence generation were evaluated by flow cytometry (FCM) and microscopy.

RESULTS

Exposure of A. carterae to toxic levels of copper impaired cell mobility, delayed cell proliferation, led to increased green autofluorescence, and at 3.13 microM labile copper also induced encystment and death. Chlorophyll fluorescence, however, was not affected. Kinetic FCM assay of FDA-dependent fluorescence generation showed a dose-dependent enhancement of fluorescein fluorescence immediately after copper addition and in cultures with sustained exposure to this toxicant.

CONCLUSIONS

Our data suggest that copper toxicity occurs quickly at the membrane level in relation to oxidative stress generation. Based on fluorescence kinetic studies, the Na(+)/H(+) antiporter seemed to be affected by copper, thereby affecting intracellular pH.

The relevance of flow cytometry for biochemical analysis

Flow cytometry (FCM) allows the simultaneous measurement of multiple fluorescences and light scatter induced by illumination of single cells or microscopic particles in suspension, as they flow rapidly through a sensing area. In some systems, individual cells or particles may be sorted according to the properties exhibited. By using appropriate fluorescent markers, FCM is unique in that multiple structural and functional parameters can be quantified simultaneously on a single-particle basis, whereas up to thousands of biological particles per second may be examined. FCM is increasingly used for basic, clinical, biotechnological, and environmental studies of biochemical relevance. In this critical review, we summarize the main advantages and limitations of FCM for biochemical studies and discuss briefly the most relevant parameters and analytical strategies. Graphical examples of the biological information provided by multiparametric FCM are presented. Also, this review contains specific sections on flow cytoenzymology, FCM analysis of isolated subcellular organelles, and cell-free FCM.

Isolation of a Candida albicans gene, tightly linked to URA3, coding for a putative transcription factor that suppresses a Saccharomyces cerevisiae aft1 mutation

A pathogen such as C. albicans needs an efficient mechanism of iron uptake in an iron-restricted environment such as is the human body. A ferric-reductase activity regulated by iron and copper, and analogous to that in S. cerevisiae, has been described in C. albicans. We have developed an in-plate protocol for the isolation of clones that complement an aft1 mutation in S. cerevisiae that makes cells dependent on iron for growth. After transformation of S. cerevisiae aft1 with a C. albicans library, we have selected clones that grow in conditions of iron deficiency and share an identical plasmid, pIRO1, with a 4500 bp insert containing the URA3 gene and an ORF (IRO1) responsible for the suppression of the iron dependency. IRO1 does not show homology with AFT1 or with other sequences in the databases. Northern analysis demonstrates constitutive expression of IRO1. CAI4, a C. albicans strain isolated as Deltaura3, also has a deletion of the 3' half of IRO1, and displays in YNB medium similar phenotypic characteristics to S. cerevisiae aft1 mutant strains. Therefore, we consider IRO1 as a gene of C. albicans involved in the utilization of iron. However, in extreme conditions of iron deprivation, CAI4 seems to activate alternative mechanisms of iron uptake that allow a better growth than the wild strain SC5314. Analysis of its predicted protein sequence is in agreement with a role of Iro1p as a transcription factor.

Human endometrial mucin MUC1 is up-regulated by progesterone and down-regulated in vitro by the human blastocyst

Expression of MUC1 in endometrial epithelium has been suggested to create a barrier to embryo attachment that must be lifted at the time of implantation. In this study, we investigated the hormonal regulation of human endometrial MUC1 in hormone replacement therapy cycles and in the human blastocyst. We also analyzed the embryonic regulation of MUC1 in human endometrial epithelial cells (EECs) during the apposition and adhesion phases of human implantation using two different in vitro models. Our results indicate that endometrial MUC1 mRNA and immunoreactive protein increase in receptive endometrium compared to nonreceptive endometrium. Human blastocysts express MUC1, as demonstrated by reverse transcription-polymerase chain reaction and immunocytochemistry, localized at the trophectoderm. In vitro, MUC1 was present at the surface of primary cultures of human EEC, and presence of a human blastocyst (i.e., apposition phase) increases EEC MUC1 protein and mRNA compared to control EEC lacking embryos. Interestingly, when human blastocysts were allowed to attach to the EEC monolayer (i.e., adhesion phase), MUC1 was locally removed in a paracrine fashion on EEC at the implantation site. These results demonstrate a coordinated hormonal and embryonic regulation of EEC MUC1. Progesterone combined with estradiol priming induces an up-regulation of MUC1 at the receptive endometrium. During the apposition phase, presence of a human embryo increases EEC MUC1. However, at the adhesion phase, the embryo induces a paracrine cleavage of EEC MUC1 at the implantation site. These findings strongly suggest that MUC1 may act as an endometrial antiadhesive molecule that must be locally removed by the human blastocyst during the adhesion phase.

The human blastocyst regulates endometrial epithelial apoptosis in embryonic adhesion

The implanting blastocyst must appose and adhere to the endometrial epithelium and, subsequently, invade it. Locally regulated uterine epithelial apoptosis induced by the embryo is a crucial step of the epithelial invasion in rodents. To address the physiological relevance of this process in humans, we investigated the effect of single human blastocysts on the regulation of apoptosis in cultured human endometrial epithelial cells (hEEC) in both apposition and adhesion phases of implantation. Here, we report a co-ordinated embryonic regulation of hEEC apoptosis. In the apposition phase, the presence of a blastocyst rescues hEEC from the apoptotic pathway. However, when the human blastocyst adheres to the hEEC monolayer, it induces a paracrine apoptotic reaction. Fas ligand (Fas-L) was present at the embryonic trophoectoderm. Fas was localized at the apical cell surface of hEEC, and flow cytometry revealed that 60% of hEEC express Fas. Neutralizing adhesion assays revealed that the Fas/Fas-L death system may be an important mechanism to cross the epithelial barrier, which is crucial for embryonic adhesion, and the manipulation of this system could have potential clinical implications as an interceptive mechanism.

Phenotypic analysis of peripheral lymphocyte subpopulations in hydatid patients

Peripheral T-lymphocytes were analyzed in three groups of people: (1) individuals with current liver hydatid disease (hydatid patients, n = 20), (2) persons who had undergone surgical cyst removal at least 2 years previously (recovered patients, n = 9), and (3) a control group of healthy volunteers (uninfected controls, n = 13). Group 1 was subdivided according to cyst status, relapse of disease, and the presence or absence of symptoms. Percentages of lymphocytes expressing CD3, CD4, CD8, CD56, CD25, CD45RA, CD45RO, and HLA-DR were determined. Symptomatic patients had proportionally fewer CD3+ CD8 + lymphocytes than the control group (P=0.038). Hydatid patients with active cysts had proportionally more natural killer cells (CD56 + CD8-) than the control group (P = 0.028).

Flow cytometric analysis of peroxidative activity in granulocytes from coronary and peripheral blood in acute myocardial ischemia and reperfusion in dogs: protective effect of methionine

BACKGROUND

Methionine has shown protective effects in experimental models of myocardial infarction and is highly reactive to oxidative compounds produced by polymorphonuclear leukocytes (PMN), which in turn have been associated with myocardial damage. We have investigated the effect of methionine administration on spontaneous leukocyte peroxidative activity in myocardial ischemia and reperfusion.

METHODS

In anesthetized dogs, with coronary occlusion (90 min) and reperfusion (90 min), PMN activation was measured by flow cytometric determination of H(2)O(2) with dihydrorhodamine 123, and correlated to hemodynamic parameters and infarct presence. To assess a possible direct effect of methionine, H(2)O(2) and superoxide were measured by flow cytometry in dog leukocyte suspensions following in vitro stimulation with f-MLP.

RESULTS

PMN peroxidative activity in saline-treated dogs increased significantly after coronary occlusion and after reperfusion. These changes were greater in coronary venous blood than in femoral blood. Methionine administration (150 mg/kg, i.v.) before occlusion totally suppressed PMN activation, both after occlusion and reperfusion.

CONCLUSIONS

PMN are promptly activated in myocardial ischemia, and methionine administration prevents such activation. However, methionine has no direct effect on spontaneous peroxidative activity, and f-MLP induced peroxidative activity. These in vivo effects of methionine, may additionally contribute to explain its protective role in experimental -788-877-7QQ8-8-7-88-8-8778--8Q78-----8--8-Q-7-Q7----- --------------8888 888888-7777777777777777777777777777777----------------888888888888888888 8877777--87--------8-----------------7-8888-887-----------8----8-8-87777 7777777------------------------------------------------------T7OW

Intratumoral heterogeneity of DNA content in renal cell carcinoma and its prognostic significance

BACKGROUND

A multiple sampling study was performed on 124 specimens of renal cell carcinomas to analyze the consistency and reliability of DNA measurements. The authors investigated intratumoral DNA heterogeneity and its role as a adverse prognostic factor for disease progression.

METHODS

DNA content was analyzed by flow cytometry on three different samples of the same tumor. The Cronbach alpha coefficient was used to assess the reliability and a Cox proportional hazards model was used to test the effect of DNA ploidy heterogeneity on time of disease progression.

RESULTS

The agreement among the DNA ploidy samples was high. The number of aneuploid findings increased significantly with the number of samples analyzed. The presence of non-diploid cell populations was a significant adverse predictive value for disease progression. However, the authors were unable to demonstrate that intratumoral heterogeneity DNA content had any influence on the biological behavior of the tumor.

CONCLUSIONS

Determination of DNA ploidy based on single samples may be inaccurate. Spatial variation in DNA ploidy is a feature of renal cell carcinoma; however, its biologic significance remains to be demonstrated.

Flow cytometric kinetic assay of calcium mobilization in whole blood platelets using Fluo-3 and CD41

BACKGROUND

Platelet activation plays a major role in the physiology and pathology of hemostasis. Flow cytometry is a promising approach for the structural and functional analysis of platelets. However, the choice of adequate biological parameters and most technical issues are still under discussion. A rise in cytosolic free Ca2+ is a key early event that follows platelet stimulation and precedes several activation responses, including shape change, aggregation, secretion, and expression of procoagulant activity. Our objective was to set up a fast and sensitive flow cytometric method to determine the kinetics of intracellular Ca2+ mobilization in platelets, which could be performed with the least artifactual perturbation of platelet function.

METHODS

Anticoagulated blood was diluted in Tyrode's buffer and incubated with Fluo-3-acetoxymethyl ester prior to staining with phycoerytrin-conjugated antiplatelet GPIIb/IIIa complex monoclonal antibody. Platelets were identified by a gate including only CD41+ events. After the determination of baseline Fluo-3 green fluorescence on a flow cytometer (EPICS XL-MCL, Coulter Electronics, Hialeah, FL), adequate agonists were added and time-dependent changes in Fluo-3 fluorescence were recorded on-line for up to 3 min.

RESULTS

In these conditions, a very fast and transient increase of cytosolic-free Ca2+ was observed following the addition of thrombin, a strong platelet agonist. Stimulation with adenosine diphosphate (ADP), a weak agonist, also resulted in evident increase of Ca2+ levels.

CONCLUSIONS

Our results show that this flow cytometric kinetic method provides a simple and sensitive tool to assess in vitro the time course and intensity of signal transduction responses to different platelet agonists under near physiological conditions. In this way, it may be useful to evaluate the degree of platelet reactivity and thus to monitor antiplatelet therapy.

Detection of oxidative mutagenesis by isoniazid and other hydrazine derivatives in Escherichia coli WP2 tester strain IC203, deficient in OxyR: strong protective effects of rat liver S9

Strain IC203, deficient in the OxyR function, was sensitive to both cytotoxic and mutagenic effects of isoniazid (INH) whereas its parent, WP2 uvrA/pKM101, was resistant to these effects. Four other hydrazine compounds, hydrazine hydrate (HZH), phenylhydrazine (PHZ), hydralazine (HLZ) and nialamide (NLD), were mutagenic in WP2 uvrA/pKM101. Increases in mutagenicity were observed in IC203 for HZH and PHZ but not for HLZ and NLD. Growth inhibition zones by HZH, PHZ and NLD were larger in IC203 than in WP2 uvrA/pKM101. The enhancements in the effects of INH, HZH and PHZ in IC203 with respect to its oxyR+ parent are considered to be caused by the production of reactive oxygen species. This is consistent with its inhibition in IC203 by S9 from liver of uninduced rats, probably through the action of catalase. Mutagenicities of INH, PHZ and HLZ were low in strains IC204, a derivative of WP2 uvrA carrying a deletion of the umuDC genes, and IC206, a derivative of IC204 deficient in the MutY glycosylase. In these strains, HZH and NLD induced a high level of revertants which carry suppressor mutations resulting exclusively from G:C-A:T transitions, thus suggesting a direct reaction of the two hydrazines with cytosine.

Embryonic regulation of integrins beta 3, alpha 4, and alpha 1 in human endometrial epithelial cells in vitro

In the present study, we examined the embryonic regulation of beta 3 integrin in human endometrial epithelial cells (EEC) at the protein level and analyzed putative embryonic factors responsible for this regulation. The model employed is based on a clinical in vitro fertilization program in which single human embryos were cocultured with EEC until blastocyst stage and then transferred back to the uterus. After embryo transfer, EEC wells were divided according to the embryonic status reached: EEC with embryos that achieved the blastocyst stage, EEC with arrested embryos, and EEC without embryos. Immunostaining for beta 3 was positive in plasma membrane of EEC. Flow cytometry showed a mean percentage of beta 3-stained cells of 24.1 +/- 5.7 in EEC cocultured with embryos that achieved the blastocyst stage (n = 13) vs. 9.5 +/- 1.6 (P < 0.05) in those EEC cultured with arrested embryos (n = 12). Immunostaining for alpha 1 and alpha 4 integrins was negative in EEC monolayers studied, regardless of the presence or absence of embryos, and these findings were confirmed by flow cytometry. The possibility that the embryonic IL-1 system and leukemia inhibitory factor were involved in the endometrial beta 3 up-regulation was investigated by neutralizing experiments demonstrating a significant inhibition of beta 3-stained cells when EEC monolayers were cultured in the presence of EEC/blastocyst-conditioned media with (n = 4) vs. without (n = 8) antihuman interleukin (IL)-1 alpha + IL-1 beta (1.65% vs. 14.6%; P < 0.05). Dose-response experiments further demonstrated an up-regulation of beta 3 positive cells when IL-1 alpha + IL-1 beta were added to the medium at a concentration of 10 pg/mL compared with control medium without added cytokines (40% vs. 20%, n = 4). The functional relevance of the EEC beta 3 up-regulation was tested using a mouse blastocyst adhesion assay. More mouse blastocysts attached to EEC previously in contact with human blastocyst (72.7%) compared with those EEC previously in contact with arrested embryos (40%). Our results demonstrate the selective effect of a developing human embryo on EEC expression of beta 3, which is maximal when a human blastocyst instead of an arrested embryo is considered. Furthermore, the embryonic IL-1 system seems to be involved in the EEC beta 3 up-regulation, reinforcing the concept of precise paracrine cross-talk between blastocyst and endometrial epithelium during embryonic implantation.

The glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase of Candida albicans is a surface antigen

A lambda gt11 cDNA library from Candida albicans ATCC 26555 was screened by using pooled sera from two patients with systemic candidiasis and five neutropenic patients with high levels of anti-C. albicans immunoglobulin M antibodies. Seven clones were isolated from 60,000 recombinant phages. The most reactive one contained a 0.9-kb cDNA encoding a polypeptide immunoreactive only with sera from patients with systemic candidiasis. The whole gene was isolated from a genomic library by using the cDNA as a probe. The nucleotide sequence of the coding region showed homology (78 to 79%) to the Saccharomyces cerevisiae TDH1 to TDH3 genes coding for glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and their amino acid sequences showed 76% identity; thus, this gene has been named C. albicans TDH1. A rabbit polyclonal antiserum against the purified cytosolic C. albicans GAPDH (polyclonal antibody [PAb] anti-CA-GAPDH) was used to identify the GAPDH in the beta-mercaptoethanol extracts containing cell wall moieties. Indirect immunofluorescence demonstrated the presence of GAPDH at the C. albicans cell surface, particularly on the blastoconidia. Semiquantitative flow cytometry analysis showed the sensitivity of this GAPDH form to trypsin and its resistance to be removed with 2 M NaCl or 2% sodium dodecyl sulfate. The decrease in fluorescence in the presence of soluble GAPDH indicates the specificity of the labelling. In addition, a dose-dependent GAPDH enzymatic activity was detected in intact blastoconidia and germ tube cells. This activity was reduced by pretreatment of the cells with trypsin, formaldehyde, and PAb anti-CA-GAPDH. These observations indicate that an immunogenic, enzymatically active cell wall-associated form of the glycolytic enzyme GAPDH is found at the cell surface of C. albicans cells.

Flow cytometry, sorting and immunocharacterization with proliferating cell nuclear antigen of cycling and non-cycling cells in synchronized pea root tips

In the 3-d-old 2-mm root tip of Pisum sativum L. cv. Lincoln the percentage of actively proliferating cells is estimated to be 70%. The remaining cells are non-cycling and arrested with 2C and 4C DNA content in G0 and in G2Q, respectively. In this work we studied the kinetic significance of these quiescent cells, using the sorting capabilities of flow cytometry and immunofluorescence techniques to detect the proliferation marker PCNA (proliferating cell nuclear antigen) inside cells within the different cell-cycle compartments. While in animal cells, PCNA is present at a high level only in actively proliferating cells, in 3-d-old pea root tips 95% of the cells are PCNA-positive. After flow cytometry and sorting of pea non-cycling nuclear populations, all G2Q nuclei appeared strongly PCNA-positive, indicating that these cells had recently left the cell cycle. By contrast, most G0 nuclei showed a low level of PCNA immunofluorescence intensity, as measured by image analysis, with about 25% of the nuclei being PCNA-negative. This small percentage was found to correspond to root cap cells, as could be observed in the root tip section. These are the only cells in the root apical region which are fully differentiated and which, therefore, lack the competence to enter the cell cycle. In contrast, the more or less PCNA-positive G0 nuclei could represent a kinetically heterogeneous population of cells competent to proliferate, but which have either recently left the cell cycle or are progressing to the G0-G1 transition.

Is rhodamine 123 an appropriate fluorescent probe to assess P-glycoprotein mediated multidrug resistance in vinblastine-resistant CHO cells?

Cellular drug resistance, which involves several mechanisms such as P-glycoprotein (P-gp) overexpression, kinetic and metabolic quiescence, or the increase in the intracellular levels of glutathione, limits the effectiveness of cancer treatment. It has been reported that functional assessment of the cationic dye rhodamin 123 (Rho123) efflux reveals accurately the drug-resistant phenotype. To study cellular drug resistance, we have obtained a CHO-K1 derived cell line resistant to vinblastine by means of multistep selection. This cell line (CHOVBR) displays high reactivity with a monoclonal antibody (MAb) (C219) directed against an internal domain of P-gp, and an active Rho123 efflux, as shown by parallel flow cytometric and fluorometric assays. However, under similar experimental conditions, the drug-sensitive parental cell line CHO-K1 (as well as the myeloblastic KG1 and KG1a cell lines), was also able to pump Rho123 out. These parental CHO-K1 cells had a very low reactivity against the C219 Mab, as confirmed by Western blot analysis. Both vinblastine and verapamil inhibited Rho123 efflux in CHO-K1 cells, but had no effect on CHOVBR cultures. Also, deprivation of vinblastine for one month did not affect Rho123 efflux in these cells. Our results suggest that the activity of P-gp appears to be essential, but not sufficient to confer drug resistance, and that Rho123-based functional assays of drug resistance should be evaluated for each cellular experimental model.

Binding of extracellular matrix proteins to Aspergillus fumigatus conidia

As detected by confocal immunofluorescence microscopy, binding of fibronectin and laminin appeared to be associated with the protrusions present on the outer cell wall layer of resting Aspergillus fumigatus conidia. Flow cytometry confirmed that binding of laminin to conidia was dose dependent and saturable. Laminin binding was virtually eliminated in trypsin-treated organisms, thus suggesting the protein nature of the binding site. Conidia were also able to specifically adhere to laminin immobilized on microtiter plates. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting (immunoblotting) with laminin and antilaminin antibody of whole conidial homogenates allowed identification, among the complex array of protein and glycoprotein species, of one polypeptide with an apparent molecular mass of 37 kDa which specifically interacts with laminin. The fact that binding of conidia to soluble or immobilized laminin or fibronectin was inhibited by fibronectin or laminin, respectively, suggests the existence of common binding sites for both ligands on the surface of conidia. Intact conidia were also able to adhere to type I and IV collagen immobilized on microtiter plates; adhesion was found to be dose dependent and saturable. Adhesion to immobilized type I and IV collagen was markedly inhibited by laminin and weakly inhibited by fibronectin. Coincubation of conidia with Arg-Gly-Asp (RGD) peptides caused a dose-dependent decrease in binding of cells to immobilized or soluble fibronectin, yet interaction of cells with soluble or immobilized laminin and type I and IV collagen remained unaffected. Interactions described here could be important in mediating attachment of the fungus to host tissues, thus playing a role in the establishment of the disease.

Aging of the liver: age-associated mitochondrial damage in intact hepatocytes

Mitochondrial damage may be a major cause of cellular aging. So far, this hypothesis had only been tested using isolated mitochondria. The aim of this study was to investigate the involvement of mitochondria in aging using whole liver cells and not isolated mitochondria only. Using flow cytometry, we found that age is associated with a decrease in mitochondrial membrane potential (30%), an increase in mitochondrial size, and an increase in mitochondrial peroxide generation (23%). Intracellular peroxide levels were also increased. The number of mitochondria per cell and inner mitochondrial membrane mass did not change. Gluconeogenesis from glycerol or fructose (mitochondrial-independent) did not change with age, whereas it did from lactate (mitochondrial-dependent). The change in the rate of gluconeogenesis was not accompanied by changes in any of the following parameters: phosphoenolpyruvate carboxykinase or pyruvate carboxylase activities or mitochondrial ATP/ADP or cytosolic NADH/NAD+ ratios. This was caused by a decreased rate of malate export (to 20% of the controls) from mitochondria. The impairment of the mitochondrial malate transporter is posttranscriptional because its expression in Xenopus oocytes using polyadenylated RNA from livers of young or old animals did not change. Ketogenesis from oleate also fell in hepatocytes from old rats. Our results show, for the first time in intact cells, a correlation between age-associated impairment of cell metabolism and specific changes in mitochondrial function and morphology, supporting the hypothesis that mitochondrial damage plays a key role in aging.

Oxidative metabolism in a rat hepatoma (N13) and isolated rat hepatocytes: a flow cytometric comparative study

Recently, we have developed a new and fast kinetic method for assessing mitochondrial membrane potential by flow cytometry, based on the quantitation of the initial rate of rhodamine 123 (Rh123) uptake by living cells. This test has proved suitable to detect metabolic and toxic effects on mitochondria. To characterize energy metabolism in a rat hepatoma cell line (N13), we applied this method to assess several metabolic pathways that eventually generate mitochondrial membrane potential. Using this approach, we found that N13 hepatoma cells retain an oxidative capacity comparable with that observed in isolated hepatocytes under the same conditions. These results show that this cell line may represent an adequate biological model to perform metabolic and toxicological studies in vitro.

Binding of human fibronectin to Aspergillus fumigatus conidia

Aspergillus fumigatus conidia exhibited the ability to bind purified human fibronectin, whereas mycelial forms did not bind the ligand, as detected by an indirect immunofluorescence assay with an antifibronectin polyclonal antibody after incubation of the cells with fibronectin. Flow cytometry confirmed that binding of the ligand to conidia was dose dependent and saturable. Pretreatment of the cells with trypsin markedly reduced binding, which suggested a protein nature for the binding sites present at the surface of conidia. Intact conidia were also able to adhere to fibronectin or antifibronectin antibodies, a significant reduction (from 88 to 92%) in the binding of conidia was noticed, thus suggesting that adhesion to the immobilized ligand was specific. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western immunoblotting with fibronectin and antifibronectin antibody of whole conidial homogenates and 2-mercaptoethanol extracts from isolated conidial cell walls allowed identification, among the complex array of protein and glycoprotein species present in both cell-free preparations, of two polypeptides with apparent molecular masses of 23 and 30 kDa which specifically interact with fibronectin.

Value of deoxyribonucleic acid ploidy and nuclear morphometry for prediction of disease progression in renal cell carcinoma

PURPOSE

A retrospective study was performed on 108 patients with localized renal cell carcinoma (pT1 to 3a N0M0) to determine whether ploidy and nuclear morphometry are independent predictive factors in addition to stage and grade.

MATERIALS AND METHODS

Deoxyribonucleic acid (DNA) content was analyzed by flow cytometry and nuclear morphometry characterized by 5 nuclear descriptors. A Cox proportional hazards regression model was used to identify significant prognostic factors for disease progression.

RESULTS

A model combining tumor stage and grade, DNA ploidy and nuclear minor axis was chosen as optimal with risk of disease progression increased with increasing tumor stage and grade, DNA aneuploidy and increasing nuclear minor axis.

CONCLUSIONS

This improved ability to predict disease progression in localized renal cell carcinoma may have important clinical use.

Study of surface carbohydrates on isolated Golgi subfractions by fluorescent-lectin binding and flow cytometry

The Golgi complex is a functionally heterogeneous subcellular structure that plays a key role in the synthesis, maturation, and sorting of newly synthesized glycoproteins. Fluorescent lectins have been used extensively to analyze surface glycoproteins by flow cytometry in whole cells and more recently in isolated subcellular organelles, such as mitochondria and chloroplasts. We report here the use of several fluorescein-isothiocyanate-conjugated lectins to detect and quantify specific surface sugars by flow cytometry on isolated elements from purified cis and trans-Golgi fractions from rat liver. Our results show that this approach may be useful to study Golgi composition and function, since it may reveal the intensity of specific binding of different lectins to each Golgi fraction and the percentage of elements binding the lectins specifically. Thus we show here that Golgi elements appear homogeneous in mannose and fucose, whereas galactose and N-acetyl-glucosamine residues are more abundant in the trans-Golgi elements.

A fast kinetic method for assessing mitochondrial membrane potential in isolated hepatocytes with rhodamine 123 and flow cytometry

Rhodamine 123 (Rh123) is widely used as a flow cytometric probe for mitochondrial membrane potential (MMP) in metabolic, pharmacologic, and toxicological studies. However, the use of relatively high concentrations of Rh123 (up to 10 micrograms/ml) and prolonged incubation times (up to 1 h), including washing steps, may be inconvenient for certain applications in which labile cells are used or which demand rapid or repeated analysis. In this paper we describe a rapid kinetic assay of MMP in isolated rat hepatocytes, based upon the quantitation of the initial rate of Rh123 uptake by living cells, selected by their scattering properties. The results indicate that at an appropriate dye-to-cell ratio (in our experiments, 50 ng Rh123/ml for 250,000-300,000 cells/ml), the initial rate of Rh123 uptake is a highly reproducible and sensitive parameter for estimation of MMP, as demonstrated by the effects of substrates and inhibitors of the glycolytic pathway and mitochondrial respiration. Because of its simplicity, rapidity (about 5 min) and metabolic implications, this assay would be also suitable for the routine evaluation of metabolic state of cell suspensions, as a complementary test to the standard dual-staining tests of viability. Other possible applications in screening pharmacologic and toxicological analysis are discussed.

[Fine-needle puncture-aspiration in the measurement of the DNA content by flow cytometry in head and neck tumors. Methodology and applications]

Fine needle aspiration was used to obtain samples from 15 patients with head and neck tumors for posterior analysis of their DNA content by flow cytometry. This technique afforded rapid and readily reproducible high quality histograms. A review was made of the malignancy criteria according to variations in DNA content. Good patient tolerance made it possible to apply the technique repeatedly to obtain samples for DNA analysis by flow cytometry, a method of great interest in monitoring response to different treatment protocols (chemotherapy, radiotherapy).

Glutathione metabolism in primary astrocyte cultures: flow cytometric evidence of heterogeneous distribution of GSH content

The time-course of intracellular glutathione (GSH) values after incubation with L-buthionine-(S,R)-sulfoximine (BSO), a selective inhibitor of gamma-glutamylcysteine synthetase, showed that glutathione turns over with a half-life of 5 h. Intracellular GSH was assayed by flow cytometry using three different methods. Astrocytes showed a narrow range of cellular size but a wide range of intracellular GSH. This heterogeneity was resolved into three distinct subpopulations which represent 20%, 35% and 45% of the total astrocyte number. The less abundant subpopulation had the lower GSH content, while the most abundant was the subpopulation with the higher content. Over 95% of astrocytes were in the G0/G1 phase of the cell cycle, the distribution of cytosolic pH was homogeneous and the number of viable cells at the time of the assay was 90%. These results show that several pools exist when astrocyte GSH is considered and these findings may be relevant to the understanding of brain GSH metabolism.

Flow cytometric analysis of concanavalin A binding to isolated Golgi fractions from rat liver

Flow cytometry (FCM) has been used repeatedly to study lectin binding to whole cells. However, there are very few attempts to analyze glycoconjugates in isolated subcellular organelles. We have applied FCM to quantitate the specific binding of fluorescein-conjugated concanavalin A (FITC-Con A) to isolated cis and trans fractions of rat liver Golgi complex, the cell compartment involved in glycoprotein maturation and sorting. Our results show similar intensities of Con A-specific binding in the two fractions. Using this method we show a decreased FITC-Con A binding to both Golgi fractions in ethanol-treated rats, which is consistent to previous work on alcoholic effects on galactosyltransferase. The possible applications of this technique are discussed.

Flow-cytometric enumeration of reticulocytes with the new fluorochrome 1,3'-diethyl-4,2'-quinolylthiacyanine (correction of 1',3'-diethyl-4,2'-quinolylthiacyanine)

Several flow-cytometric methods for reticulocyte enumeration in whole blood have been developed, with different degrees of practical use. Recently, a new fluorochrome, 1,3'-diethyl-4,2'-quinolylthiacyanine (corrected) (DEQTC) was proposed in a brief report, as an alternative to thiazole orange for reticulocyte counting. We have evaluated the usefulness of this fluorescent stain by assessing the optimal conditions for the flow-cytometric analysis, and by comparing in double-blind assays the quantitative results of this technique with those obtained by manual counting with brilliant cresyl blue. Our results show that flow cytometry with DEQTC is highly correlated to the manual method (r = 0.95-0.99), supporting the interest of this particular stain and of flow cytometry for routine laboratory work in hematology.

Analysis of the membrane potential of rat- and mouse-liver mitochondria by flow cytometry and possible applications

Washed and purified rat- or mouse-liver mitochondria exhibiting high membrane integrity and metabolic activity were studied by flow cytometry. The electrophoretic accumulation/redistribution of cationic lipophilic probes, rhodamine 123, safranine O and a cyanine derivative, 3,3'-dihexyloxadicarbocyanine iodide, during the energization process was studied and was consistent with the generation of a negative internal membrane potential. An exception to this was nonylacridine orange which spontaneously bound to the mitochondrial membrane by hydrophobic interactions via its hydrocarbon chain. Energized purified mitochondria stained with potentiometric dyes exhibited both higher fluorescence and population homogeneity than the non-energized or deenergized (nigericin plus valinomycin) mitochondria. By contrast, under non-energized or deenergized conditions, the mitochondrial population exhibited fluorescence intensity heterogeneity related to the residual membrane potential; two subpopulations were evident, one of low fluorescence which may be related to the autofluorescence of the mitochondria (plus non-specific dye binding) and a second population which exhibited high fluorescence. Flow cytometry of the unpurified, simply washed, rat-liver mitochondria stained with rhodamine 123, a classically used dye, provided evidence of their heterogeneity in terms of light-scattering properties and membrane-potential-related fluorescence. One third of the washed mitochondria were found to be non-functional by such assays. The fluorescence of purified rat-liver mitochondria due to the membrane potential built up by endogenous substrates indicates heterogeneity of the mitochondrial population with respect to levels of endogenous substrates. The low-angle light scattering increases upon energization and provides some original information about the shape and modification of the inner mitochondrial conformation accompanying the energization. The heterogeneity of the rat liver mitochondrial population, from a structural, metabolic (existence of endogenous substrates) and functional (active and non-active mitochondrial population dispersion) point of view could thus be demonstrated by flow-cytometry analysis. Two animal models were examined with regard to the alteration of the mitochondrial membrane potential under the effects of drugs (rat-liver mitochondria), and the effects of ammonium toxicity (mouse-liver mitochondria). These results are promising and open new perspectives in the study of mitochondriopathies.

A smaller initial dose protects mice against several lethal doses of ammonium acetate

The synthesis of urea in the liver is the main mechanism for the elimination of excess ammonia. Rapid stimulation of the synthesis of urea (e.g. by administration of carbamyl glutamate, the analog of the physiological activator of carbamyl phosphate synthetase I) protects animals given lethal doses of ammonia. Since ammonia enhances the activity of the urea cycle, we tested and show here that administration of small doses of ammonium acetate supresses the mortality induced by a series of repeated LD100 of ammonium acetate separated by one hour, when the first LD100 is injected i.p. starting from 30 min to 5 hours after the initial smaller dose of ammonium acetate. Under these conditions, the levels of ammonia in blood are elevated more than ten times, but in spite of the greater amount of ammonia administered, the ammonemia is much lower than in mice dying after a single LD100. The enhanced synthesis of urea observed is correlated with an increase in the intramitochondrial content of N-acetyl glutamate. These findings are of interest as far as the short-term regulation of urea cycle, the mechanism of ammonia toxicity and have clinical implications.

New roles of carnitine metabolism in ammonia cytotoxicity

High levels of ammonia in blood and brain due to metabolic disorders are associated with neurological abnormalities. Although the mechanism of ammonia toxicity at the CNS level is still unknown, alterations in brain energy metabolism, in neurotransmitter function and direct effects on nervous impulse have been proposed. In most hyperammonemic conditions morphological changes in the liver and brain have been demonstrated, especially in mitochondria, endoplasmic reticulum and lysosomes, together with an accumulation of intracellular lipids. The treatment of hyperammonemias is uncertain and mostly directed to reduce the level of circulating ammonia; there is no current therapy aimed to counteract the molecular effects of ammonia. Administration of carnitine prevents acute ammonia toxicity and enhances the efficacy of ammonia elimination as urea and glutamine. In addition the cytotoxic effects of ammonia, possibly arising from lipid peroxidation, are ameliorated by carnitine. These data indicate the feasibility of utilization of carnitine in the therapy of human hyperammonemic syndromes, both for reducing the levels of ammonia and preventing its toxic effects.

Age-dependent decrease of carnitine content in muscle of mice and humans

Carnitine deficiency associated with impairment of muscle function has been described in infants and young adults as a result of inherited or acquired disease but there are no reports on carnitine levels in healthy aging people. In this paper we show a marked reduction of carnitine and its derivatives in muscle, and of long-chain acyl carnitine in heart of 6-month-old mice, when compared to animals of 6 weeks of age. Analysis of muscle samples of healthy humans of different ages showed a drastic reduction of carnitine and acetyl carnitine in the older subjects with a strong reverse correlation between age and carnitine levels.

Carbamyl glutamate prevents the potentiation of ammonia toxicity by sodium benzoate

Sodium benzoate has been recommended for the treatment of hyperammonaemia in humans. However, benzoate potentiates ammonia toxicity and reduces urea synthesis in vitro and in vivo by decreasing the intramitochondrial levels of N-acetyl glutamate. Pretreatment of mice with carbamyl glutamate, a structural analogue of N-acetyl glutamate, decreases mortality induced by ammonium acetate and sodium benzoate administration. The protective effect of carbamyl glutamate is accompanied by an increase in urea production and of carbamyl phosphate synthetase activity.

A flow cytometric assay for intracellular nonprotein thiols using mercury orange

The level of nonprotein thiols was assayed in individual mammalian cells using flow cytometry. Previous determinations of glutathione (GSH, the most abundant nonprotein thiol in most cells) by flow cytometry were based on UV laser excitation of fluorochromes. Because of several shortcomings of UV excitation, an assay for GSH using visible light is of interest. Selective staining of nonprotein thiols with mercury orange (a mercurial compound that binds stoichiometrically to sulfhydryl groups) was obtained by restricting the staining time. By using various drugs that affect GSH levels and overall thiol levels in cells, it was shown that GSH is the primary thiol group being stained. Thus a quick, specific technique using mercury orange has been developed for the flow cytometric determination of nonprotein thiols and preferentially for GSH in individual mammalian cells.

Flow cytometric analysis of the effects of high protein diet on isolated rat liver mitochondria

We have investigated changes that occur in mitochondria obtained from the livers of rats that had been maintained on a high protein diet (80% casein instead of 20%) for 6 months. Liver homogenates were separated by centrifugation into a mitochondrial fraction, a nuclear fraction and the supernatant fluid of the nuclear fraction (nuclear wash). Rhodamine-123 was used to selectively stain mitochondria depending upon their membrane potential. The stained organelles were processed through a flow cytometer where the fluorescent stains were excited by the 488 nm wavelength of a laser and the resultant fluorescence signals analysed. After 6 months on a high protein diet, mitochondria displayed an increase in the fluorescence associated with rhodamine-123 uptake in both mitochondrial and nuclear wash fractions, while mitochondrial fluorescence in the nuclear fraction showed a heterogeneous distribution. This was interpreted as an increase in membrane potential in most of the liver mitochondria under these nutritional conditions, with a certain degree of heterogeneity. These functional changes may be correlated with morphological alterations previously reported and show the usefulness of flow cytometry for biochemical analysis of isolated mitochondria.