Protein misfolding and clearance in the pathogenesis of a new infantile onset ataxia caused by mutations in PRDX3

Peroxiredoxin 3 (PRDX3) encodes a mitochondrial antioxidant protein which is essential for the control of reactive oxidative species (ROS) homeostasis. So far, PRDX3 mutations are involved in mild-to-moderate progressive juvenile onset cerebellar ataxia. We aimed to unravel the molecular bases underlying the disease in an infant suffering from cerebellar ataxia that started at 19 months old and presented severe cerebellar atrophy and peripheral neuropathy early in the course of disease. By whole exome sequencing, we identified a novel homozygous mutation, PRDX3 p.D163E, which impaired the mitochondrial ROS defense system. In mouse primary cortical neurons, the exogenous expression of PRDX3 p.D163E was reduced and triggered alterations in neurite morphology and in mitochondria. Mitochondrial computational parameters showed that p.D163E led to serious mitochondrial alterations. In transfected HeLa cells expressing the mutation, mitochondria accumulation was detected by correlative light electron microscopy (CLEM). Mitochondrial morphology showed severe changes, including extremely damaged outer and inner membranes with a notable cristae disorganization. Moreover, spherical structures compatible with lipid droplets were identified, which can be associated with a generalized response to stress and can be involved in the removal of unfolded proteins. In the patient's fibroblasts, PRDX3 expression was nearly absent. The biochemical analysis suggested that the mutation p.D163E would result in an unstable structure tending to form aggregates that trigger unfolded protein responses via mitochondria and endoplasmic reticulum. Altogether, our findings broaden the clinical spectrum of the recently described PRDX3-associated neurodegeneration and provide new insight into the pathological mechanisms underlying this new form of cerebellar ataxia.

Expanding the β-III Spectrin-Associated Phenotypes toward Non-Progressive Congenital Ataxias with Neurodegeneration

(1) Background: A non-progressive congenital ataxia (NPCA) phenotype caused by β-III spectrin (SPTBN2) mutations has emerged, mimicking spinocerebellar ataxia, autosomal recessive type 14 (SCAR14). The pattern of inheritance, however, resembles that of autosomal dominant classical spinocerebellar ataxia type 5 (SCA5). (2) Methods: In-depth phenotyping of two boys studied by a customized gene panel. Candidate variants were sought by structural modeling and protein expression. An extensive review of the literature was conducted in order to better characterize the SPTBN2-associated NPCA. (3) Results: Patients exhibited an NPCA with hypotonia, developmental delay, cerebellar syndrome, and cognitive deficits. Both probands presented with progressive global cerebellar volume loss in consecutive cerebral magnetic resonance imaging studies, characterized by decreasing midsagittal vermis relative diameter measurements. Cortical hyperintensities were observed on fluid-attenuated inversion recovery (FLAIR) images, suggesting a neurodegenerative process. Each patient carried a novel de novo SPTBN2 substitution: c.193A > G (p.K65E) or c.764A > G (p.D255G). Modeling and protein expression revealed that both mutations might be deleterious. (4) Conclusions: The reported findings contribute to a better understanding of the SPTBN2-associated phenotype. The mutations may preclude proper structural organization of the actin spectrin-based membrane skeleton, which, in turn, is responsible for the underlying disease mechanism.

Mitochondrial Dysfunction, Oxidative Stress and Neuroinflammation in Neurodegeneration with Brain Iron Accumulation (NBIA)

The syndromes of neurodegeneration with brain iron accumulation (NBIA) encompass a group of invalidating and progressive rare diseases that share the abnormal accumulation of iron in the basal ganglia. The onset of NBIA disorders ranges from infancy to adulthood. Main clinical signs are related to extrapyramidal features (dystonia, parkinsonism and choreoathetosis), and neuropsychiatric abnormalities. Ten NBIA forms are widely accepted to be caused by mutations in the genes PANK2, PLA2G6, WDR45, C19ORF12, FA2H, ATP13A2, COASY, FTL1, CP, and DCAF17. Nonetheless, many patients remain without a conclusive genetic diagnosis, which shows that there must be additional as yet undiscovered NBIA genes. In line with this, isolated cases of known monogenic disorders, and also, new genetic diseases, which present with abnormal brain iron phenotypes compatible with NBIA, have been described. Several pathways are involved in NBIA syndromes: iron and lipid metabolism, mitochondrial dynamics, and autophagy. However, many neurodegenerative conditions share features such as mitochondrial dysfunction and oxidative stress, given the bioenergetics requirements of neurons. This review aims to describe the existing link between the classical ten NBIA forms by examining their connection with mitochondrial impairment as well as oxidative stress and neuroinflammation.

Impaired proteasome activity and neurodegeneration with brain iron accumulation in FBXO7 defect

FBXO7 is implicated in the ubiquitin-proteasome system and parkin-mediated mitophagy. FBXO7defects cause a levodopa-responsive parkinsonian-pyramidal syndrome(PPS).

METHODS

We investigated the disease molecular bases in a child with PPS and brain iron accumulation.

RESULTS

A novel homozygous c.368C>G (p.S123*) FBXO7 mutation was identified in a child with spastic paraplegia, epilepsy, cerebellar degeneration, levodopa nonresponsive parkinsonism, and brain iron deposition. Patient's fibroblasts assays demonstrated an absence of FBXO7 RNA expression leading to impaired proteasome degradation and accumulation of poly-ubiquitinated proteins.

CONCLUSION

This novel FBXO7 phenotype associated with impaired proteasome activity overlaps with neurodegeneration with brain iron accumulation disorders.

Characterization of molecular mechanisms underlying the axonal Charcot-Marie-Tooth neuropathy caused by MORC2 mutations

Mutations in MORC2 lead to an axonal form of Charcot-Marie-Tooth (CMT) neuropathy type 2Z. To date, 31 families have been described with mutations in MORC2, indicating that this gene is frequently involved in axonal CMT cases. While the genetic data clearly establish the causative role of MORC2 in CMT2Z, the impact of its mutations on neuronal biology and their phenotypic consequences in patients remains to be clarified. We show that the full-length form of MORC2 is highly expressed in both embryonic and adult human neural tissues and that Morc2 expression is dynamically regulated in both the developing and the maturing murine nervous system. To determine the effect of the most common MORC2 mutations, p.S87L and p.R252W, we used several in vitro cell culture paradigms. Both mutations induced transcriptional changes in patient-derived fibroblasts and when expressed in rodent sensory neurons. These changes were more pronounced and accompanied by abnormal axonal morphology, in neurons expressing the MORC2 p.S87L mutation, which is associated with a more severe clinical phenotype. These data provide insight into the neuronal specificity of the mutated MORC2-mediated phenotype and highlight the importance of neuronal cell models to study the pathophysiology of CMT2Z.

Active surveillance as a successful management strategy for patients with clinical stage I germ cell testicular cancer

BACKGROUND

Cancer-specific survival for patients with clinical stage I (CSI) germ cell testicular cancer (GCTC) is outstanding after inguinal orchidectomy regardless the treatment utilized. This study evaluated whether active surveillance (AS) of such patients yielded similar health outcomes to other therapeutic strategies such as adjuvant chemotherapy, radiotherapy or primary retroperitoneal lymphadenectomy as described in the literature.

PATIENTS AND METHODS

Patients with CSI GCTC were screened between January 2012 and December 2016. Patients had previously undergone inguinal orchidectomy as the primary treatment and chosen AS as their preferred management strategy after receiving information about all available strategies.

RESULTS

Out of 91 patients screened, 82 patients selected AS as their preferred management strategy. Relapse rate in the overall population was 20% (95% CI 12-30) and median time to relapse was 11.5 months (range 1.0-35.0). In patients with seminomatous tumors, relapse rate decreased to 13% and median time to relapse was 13 months; whereas in patients with non-seminomatous tumors, relapse rate was 33% (IA) or 29% (IB) and median time to relapse was 12 months in stage IA and 4.5 months in stage IB patients. All relapses were rescued with three or four cycles of chemotherapy and two also required a retroperitoneal lymphadenectomy. All patients are currently alive and free of disease.

CONCLUSIONS

The clinical outcomes of patients with CSI GCTC managed by AS in this series were excellent. This strategy limited the administration of active treatments specifically to the minority of patients who relapsed without compromising performance.

Oral health in Alzheimer's disease: a multicenter case-control study

OBJECTIVES

The aim of this case-control study was to carry out an oral health assessment on a group of Alzheimer's patients and to establish a hypothesis regarding the implication of the characteristics of the disease and the treatment of oral health.

MATERIALS AND METHODS

A total of 70 Alzheimer's patients, residents at the Alzheimer Center Reina Sofia Foundation (Madrid, Spain) and at the Alzheimer State Reference Center (Salamanca, Spain), and 36 controls (companions/acquaintances), were studied by oral examination and saliva sampling. The oral health indices DMFT/DMFS, CPI, the prosthetic condition, oral hygiene, saliva volume, and pH, as well as the specific microbiological parameters governing the risk of developing caries were assessed.

RESULTS

Alzheimer's patients exhibited, as compared to the control group, (1) fewer teeth (10.9 ± 10.5 vs 23.7 ± 6.5), (2) fewer obturations (2.2 ± 3.4 vs 6.6 ± 5.6), (3) fewer periodontally healthy sextants (0.1 ± 0.4 vs 1.4 ± 2.2), (4) worse oral hygiene (43.1 vs 72.2% brushed), (5) greater use of removable prostheses (47.8 vs 8.4%), (6) higher incidence of candida infection (11.8 vs 0.0%) and cheilitis (15.9 vs 0.0%), (7) lower salivary flow (0.6 ± 0.6 vs 1.1 ± 0.6), and (8) lower buffering capacity (46 vs 80%).

CONCLUSIONS

After taking into account the influence of age, Alzheimer's patients had worse oral health (caries and periodontal disease), more mucosal lesions (cheilitis and candidiasis), and worse saliva quantity and quality.

CLINICAL RELEVANCE

Clinicians should be aware of the implications of Alzheimer's disease in oral health, in order to stablish the effective preventive measures and the optimal treatment plan.

Mutations in the MORC2 gene cause axonal Charcot-Marie-Tooth disease

Charcot-Marie-Tooth disease (CMT) is a complex disorder with wide genetic heterogeneity. Here we present a new axonal Charcot-Marie-Tooth disease form, associated with the gene microrchidia family CW-type zinc finger 2 (MORC2). Whole-exome sequencing in a family with autosomal dominant segregation identified the novel MORC2 p.R190W change in four patients. Further mutational screening in our axonal Charcot-Marie-Tooth disease clinical series detected two additional sporadic cases, one patient who also carried the same MORC2 p.R190W mutation and another patient that harboured a MORC2 p.S25L mutation. Genetic and in silico studies strongly supported the pathogenicity of these sequence variants. The phenotype was variable and included patients with congenital or infantile onset, as well as others whose symptoms started in the second decade. The patients with early onset developed a spinal muscular atrophy-like picture, whereas in the later onset cases, the initial symptoms were cramps, distal weakness and sensory impairment. Weakness and atrophy progressed in a random and asymmetric fashion and involved limb girdle muscles, leading to a severe incapacity in adulthood. Sensory loss was always prominent and proportional to disease severity. Electrophysiological studies were consistent with an asymmetric axonal motor and sensory neuropathy, while fasciculations and myokymia were recorded rather frequently by needle electromyography. Sural nerve biopsy revealed pronounced multifocal depletion of myelinated fibres with some regenerative clusters and occasional small onion bulbs. Morc2 is expressed in both axons and Schwann cells of mouse peripheral nerve. Different roles in biological processes have been described for MORC2. As the silencing of Charcot-Marie-Tooth disease genes have been associated with DNA damage response, it is tempting to speculate that a deregulation of this pathway may be linked to the axonal degeneration observed in MORC2 neuropathy, thus adding a new pathogenic mechanism to the long list of causes of Charcot-Marie-Tooth disease.

Complexity of the Hereditary Motor and Sensory Neuropathies: Clinical and Cellular Characterization of the MPZ p.D90E Mutation

Early-onset hereditary motor and sensory neuropathies are rare diseases representing a broad clinical and genetic spectrum. Without a notable familial history, the clinical diagnosis is complicated because acquired causes of peripheral neuropathy, such as inflammatory neuropathies, neuropathies with toxic causes, and nutritional deficiencies, must be considered. We examined the clinical, electrophysiological, and pathologic manifestations of a boy with an initial diagnosis of chronic inflammatory demyelinating polyneuropathy. The progression of the disease despite treatment led to a suspicion of hereditary motor and sensory neuropathy. Genetic testing revealed the presence of the MPZ p.D90E mutation in heterozygosis. To clarify the pathogenicity of this mutation and achieve a conclusive diagnosis, we investigated the MPZ p.D90E mutation through in silico and cellular approaches. This study broadens the clinical phenotype of hereditary motor and sensory neuropathy due to MPZ mutation and emphasises the difficulty of achieving an accurate genetic diagnosis in a sporadic patient to provide an appropriate pharmacologic treatment.

Mechanisms of resistance to apoptosis in the human acute promyelocytic leukemia cell line NB4

Current frontline therapies have improved overall survival in acute promyelocytic leukemia (APL) patients to exceptional rates; however, relapse is still a problem among high-risk and old patients. Therefore, the development of better and safer therapies continues to be a goal in the treatment of this disease. In the present work, we examined three different pathways that hinder cell death in the APL cell line NB4, shedding light on the mechanisms that underlie resistance to apoptosis in these cells and that might help provide them with a proliferative advantage. We found that the proteasome inhibitor MG-132 specifically induces in NB4 cells an Nrf2-mediated antioxidant response which counteracts mitochondria-dependent apoptosis induced by the lipophilic cation dequalinium. More importantly, we also demonstrated that high basal autophagy levels and the gain-of-function of mutant p53 are intrinsic mechanisms of resistance to apoptosis in this cell line. According to our results, the pharmacological inhibition of autophagy and p53 mutants are useful tools to explore resistance to apoptosis in APL and other types of cancer and could be the bases of new therapeutic approaches that improve the efficiency and allow dose reduction of the current treatments.

[Changes in mitochondrial function induced by dequalinium precede oxidative stress and apoptosis in the human prostate cancer cell line PC-3]

Mitochondria play central roles in diverse physiological and pathological conditions associated with cell survival and death. Delocalized lipophilic cations, such as dequalinium (DQA), are accumulated in cancer cells attracted by the highly negative mitochondrial transmembrane potential of these cells. DQA showed a potent anticancer activity in cells from different malignancies. Here, we report the effect of DQA on PC-3 prostate cancer cells. Incubation with DQA at concentrations between 1.5 and 100 microM from 24 to 48 h decreases cell viability. The decrease in cell viability together with a loss of mitochondrial transmembrane potential induced an increase in reactive oxygen species production and cell death via caspase-3 dependent apoptotic pathway. QA was shown to cause moderate to strong cell death in a time and concentration dependent manner, causing a most advantageous effect at a concentration of 10 microM applied for a long 48 h time period, which might be a consequence of the kinetics of intracellular DQA accumulation in mitochondria, but also of the mechanisms of DQA-induced cell death. This data shows DQA as a promising agent against the human prostate cancer PC-3 cell line, activating the caspase-3 dependent apoptotic pathway. This fact might be beneficial for possible future applications in cancer therapy.

Predicting life satisfaction of the Angolan elderly: a structural model

Satisfaction with life is of particular interest in the study of old age well-being because it has arisen as an important component of old age. A considerable amount of research has been done to explain life satisfaction in the elderly, and there is growing empirical evidence on best predictors of life satisfaction. This research evaluates the predictive power of some aging process variables, on Angolan elderly people's life satisfaction, while including perceived health into the model. Data for this research come from a cross-sectional survey of elderly people living in the capital of Angola, Luanda. A total of 1003 Angolan elderly were surveyed on socio-demographic information, perceived health, active engagement, generativity, and life satisfaction. A Multiple Indicators Multiple Causes model was built to test variables' predictive power on life satisfaction. The estimated theoretical model fitted the data well. The main predictors were those related to active engagement with others. Perceived health also had a significant and positive effect on life satisfaction. Several processes together may predict life satisfaction in the elderly population of Angola, and the variance accounted for it is large enough to be considered relevant. The key factor associated to life satisfaction seems to be active engagement with others.

Spanish experience with the ipilimumab Expanded Access Program

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Background: Second line ipilimumab has proven efficacy in clinical trial but few is known outside this setting. Methods: We have retrospectively reviewed experience with the Expanded Access Program for Ipilimumab in Spain. We have collected data on demographics, response survival and toxicity. Ipilimumab was administered at a 3 mg/kg dose for four induction courses. Results: We have retrieved 99 expanded access ipilimumab applications that represent 40% of all possible applications. Five patients are not evaluable because they never received ipilimumab 4 due to progression and 1 declined consent. Median age is 58.5 years (30-81) and 54.3% of the patients are males. 59.6% have 3 or more metastatic locations, 50% have liver metastases, 16% have CNS metastasis and 74.6% have elevated LDH. ECOG performance status was 0 to 1 in 91.9%. Previous adyuvant treatment was received by 43.6% of the patients and consisted in high dose interferon in 85.4%. All except one patient have received previous first line chemotherapy and 34.2% have received 2 or more chemotherapy lines. Medium time from the start of metastatic disease to the start of ipilimumab was 11.2 months. 58.5% of the patients completed 4 doses of ipilimumab main reason for not completion was death or progression in 84.6% and toxicity in 5.1%. 8 patients are not evaluable for response, 5 have just completed the treatment and 3 are still on treatment. Responses are 1 (1.1%) CR, 6 (6.4%) PR, 6 (6.4%) PR with previous progression or new lesions, 13 (13.8%) SD, and 60 (63.8%) progressive disease. Reinduction treatment was offered to 5 patients 2 PR patients achieved a new PR, one PR patients a SD and 2 SD patients progressed after reinduction. Kaplan and Meier median survival is 150 days (95% CI 110,5-189.4). One year survival is 32.4% and 18 months survival 21.6%. Toxicity has been mild, skin, 20.2% grade I and 5.3% grade II, liver 7.4% grade I, 2.1% grade II, 3.2 grade III, and diarrhea 19.1% gI, 3.2% grade II and 1.1% grade IV. Only 7 patients experienced toxicity grade III to IV. Conclusions: Ipilimumab efficacy when it is used outside clinical trial is similar to the reported. There is room for improvement in patient selection as 40% of them did not completed treatment. Toxicity of the 3 mg/kg schedule is mild.

Adaptation and Initial Validation of the BRCS in an Elderly Spanish Sample

Resilience is understood as a dynamic process encompassing positive adaptation within the context of adversity. This study examined the validity of the Brief Resilient Coping Scale (BRCS), a 4-item measure designed to capture tendencies to cope with stress in a highly adaptive manner, in an elderly Spanish population. A total of 133 elderly people from an association of retired persons in Valencia (Spain) provided the responses for the validation study. The factorial validity of the scale was tested using confirmatory factor analysis, with a single dimension of resilience with adequate fit indexes emerging from this analysis. The BRCS has adequate internal consistency both at the scale and item levels. The criterion-related validity of the scale was established by correlating resilient coping with measures of coping resources and psychological well-being. The correlations with measures of personal coping resources (e.g., optimism, helplessness, self-efficacy), pain-coping behaviors, and psychological well-being were in the expected direction, and were statistically significant and large. In conclusion, the adaptation into Spanish of the BRCS seems to be a reliable and valid measure of resilient coping in the elderly population, and it could potentially be used in both clinical practice and research in the elderly.

High-speed gel microelectrophoresis, a new and easy approach for detection of PCR-amplified microbial DNA from environmental and clinical samples in microgels using conventional equipment

AIMS

Microelectrophoresis allows the detection of DNA bands using minimal amounts of sample in a short time, but commonly requires the use of special equipment which is not available in all laboratories. This fact has limited the application of this technique in microbiology despite its advantages. In this work, we describe a new approach to perform gel microelectrophoresis, named high-speed gel microelectrophoresis (HSGME), and its application for rapid detection of bacteria, protozoa and viruses in clinical, vegetal and environmental samples.

METHODS AND RESULTS

Aliquots of 0.4-1 microl of PCR product were loaded in 2 cm 1% agarose microgels and electrophoresed at high voltage (125 V cm(-1)) in conventional submarine horizontal mini-slabs. By using HSGME, single-DNA bands obtained after specific-PCR useful in diagnosis of different diseases caused by micro-organisms were detected in 5 min.

CONCLUSIONS

HSGME is a rapid and easy procedure applicable to detection of microbial genes, which is carried out using conventional equipment and thus can be performed in any research and diagnostic laboratory.

SIGNIFICANCE AND IMPACT OF THE STUDY

The performance of HSGME saves up to 90% time, material and energy costs, as well as laboratory hazardous wastes including carcinogenic agents used for visualizing DNA bands.

Regulation of apoptosis/necrosis execution in cadmium-treated human promonocytic cells under different forms of oxidative stress

Pulse-treatment of U-937 human promonocytic cells with cadmium chloride followed by recovery caused caspase-9/caspase-3-dependent, caspase-8-independent apoptosis. However, pre-incubation with the glutathione (GSH)-suppressing agent DL-buthionine-(S,R)-sulfoximine (cadmium/BSO), or co-treatment with H2O2 (cadmium/H2O2), switched the mode of death to caspase-independent necrosis. The switch from apoptosis to necrosis did not involve gross alterations in Apaf-1 and pro-caspase-9 expression, nor inhibition of cytochrome c release from mitochondria. However, cadmium/H2O2-induced necrosis involved ATP depletion and was prevented by 3-aminobenzamide, while cadmium/BSO-induced necrosis was ATP independent. Pre-incubation with BSO increased the intracellular cadmium accumulation, while co-treatment with H2O2 did not. Both treatments caused intracellular peroxide over-accumulation and disruption of mitochondrial transmembrane potential (delta psi m). However, while post-treatment with N-acetyl-L-cysteine or butylated hydroxyanisole reduced the cadmium/BSO-mediated necrosis and delta psi m disruption, it did not reduce the effects of cadmium/H2O2. Bcl-2 over-expression, which reduced peroxide accumulation without affecting the intracellular GSH content, attenuated necrosis generation by cadmium/H2O2 but not by cadmium/BSO. By contrast, AIF suppression, which reduced peroxide accumulation and increased the GSH content, attenuated the toxicity of both treatments. These results unravel the existence of two different oxidation-mediated necrotic pathways in cadmium-treated cells, one of them resulting from ATP-dependent apoptosis blockade, and the other involving the concurrence of multiple regulatory factors.

Study of drying systems for the utilization of biodegradable municipal solid wastes as animal feed

The effectiveness of different drying systems used for the dehydration of certain fractions of biodegradable municipal solid wastes with a high moisture content (fruit and vegetable remains) was analyzed. Some tests using small amounts of the material were carried out in natural and forced convection ovens. For larger quantities of wastes, a discontinuous cabinet dryer and a continuous rotary dryer were used. With these dryers, the moisture content was reduced from 800 to 100 g kg(-1). It was verified that the continuous rotary dryer was the most efficient type of equipment studied, since it allowed a dried waste to be obtained with better nutritional and microbiological qualities and in accordance to the specifications of the products for animal feeding.

The selection between apoptosis and necrosis is differentially regulated in hydrogen peroxide-treated and glutathione-depleted human promonocytic cells

Treatment with 0.2 mM hydrogen peroxide (H(2)O(2)) or with 0.5 mM cisplatin caused caspase-9 and caspase-3 activation and death by apoptosis in U-937 human promonocytic cells. However, treatment with 2 mM H(2)O(2), or incubation with the glutathione suppressor DL-buthionine-(S,R)-sulfoximine (BSO) prior to treatment with cisplatin, suppressed caspase activation and changed the mode of death to necrosis. Treatment with 2 mM H(2)O(2) caused a great decrease in the intracellular ATP level, which was partially prevented by 3-aminobenzamide (3-ABA). Correspondingly, 3-ABA restored the activation of caspases and the execution of apoptosis. By contrast, BSO plus cisplatin did not decrease the ATP levels, and the generation of necrosis by this treatment was not affected by 3-ABA. On the other hand, while all apoptosis-inducing treatments and treatment with 2 mM H(2)O(2) caused Bax translocation from the cytosol to mitochondria as well as cytochrome c release from mitochondria to the cytosol, treatment with BSO plus cisplatin did not. Treatment with cisplatin alone caused Bid cleavage, while BSO plus cisplatin as well as 0.2 and 2 mM H(2)O(2) did not. Bcl-2 overexpression reduced the generation of necrosis by H(2)O(2), but not by BSO plus cisplatin. These results indicate the existence of different apoptosis/necrosis regulatory mechanisms in promonocytic cells subjected to different forms of oxidative stress.

Effect of glutathione depletion on antitumor drug toxicity (apoptosis and necrosis) in U-937 human promonocytic cells. The role of intracellular oxidation

Treatment with the DNA topoisomerase inhibitors etoposide, doxorubicin, and camptothecin, and with the alkylating agents cisplatin and melphalan, caused peroxide accumulation and apoptosis in U-937 human promonocytic cells. Preincubation with the reduced glutathione (GSH) synthesis inhibitor l-buthionine-(S,R)-sulfoximine (BSO) always potentiated peroxide accumulation. However, although GSH depletion potentiated the toxicity of cisplatin and melphalan, occasionally switching the mode of death from apoptosis to necrosis, it did not affect the toxicity of the other antitumor drugs. Hypoxia or preincubation with antioxidant agents attenuated death induction, apoptotic and necrotic, by alkylating drugs. The generation of necrosis by cisplatin could not be mimicked by addition of exogenous H(2)O(2) instead of BSO and was not adequately explained by caspase inactivation nor by a selective fall in ATP content. Treatment with cisplatin and melphalan caused a late decrease in mitochondrial transmembrane potential (DeltaPsim), which was much greater during necrosis than during apoptosis. The administration of the antioxidant agents N-acetyl-l-cysteine and butylated hydroxyanisole after pulse treatment with cisplatin or melphalan did not affect apoptosis but attenuated necrosis. Under these conditions, both antioxidants attenuated the necrosis-associated DeltaPsim decrease. These results indicate that oxidation-mediated alterations in mitochondrial function regulate the selection between apoptosis and necrosis in alkylating drug-treated human promonocytic cells.

Turbulent crossed fluxes in incompressible flows

We show in the framework of the stochastic calculus the existence of turbulent crossed fluxes in incompressible flows. Physically, these fluxes are related to the dependence of the phenomenological coefficients on the temperature and concentration variables.

Turbulent Dufour effect and Onsager-type relations

In this paper we extend the work of Elperin et al. [Phys. Rev. Lett. 80, 69 (1998)] by showing that a turbulent Dufour-type effect is also present in chemically nonreacting gaseous admixtures. This result is used to analyze the possibility of obtaining turbulent analogs of the Onsager relations, a fundamental result for molecular crossed effects in irreversible thermodynamics.

In vivo survival of selected murine carrier red blood cells after separation by density gradients or aqueous polymer two-phase systems

In order to explore possibilities of using erythrocytes as carrier systems for delivery of pharmacological agents, we have studied the in vivo survival of murine carrier red blood cell populations enriched in young or old cells. Hypotonic-isotonic dialysis has been used to modify the cells as carrier systems and Percoll/albumin density gradients or counter-current distribution in aqueous polymer two-phase systems to separate them according to age. Hypotonic-isotonic dialysis produces a decrease in the red blood cell populations in vivo survival rate (from 9.5 to 7.8 days). Among the cells modified as carriers, the enriched young red blood cell populations show a higher in vivo survival (half-life 6.5-7.4 days) than populations made up of predominantly old red blood cells (half-life 4.7-6.2 days). Half-life of young or old circulating red blood cells was approximately one day longer when these cells were separated by counter-current distribution rather than by Percoll density gradients. Based on these results, hypotonic-isotonic dialysis of whole and enriched young or old red blood cell populations, with higher or lower survival rates, can be considered as a useful tool for modification of these cells as carriers. The final outcome of such changes can be translated into better control of plasma drug delivery during therapy.

Surface and metabolic properties of microcytic and macrocytic human anaemic red blood cells detected in polymer aqueous two-phase systems

Microcytic and macrocytic red blood cells from anaemic patients have been fractionated as a function of cell surface properties by the countercurrent distribution technique using charge-sensitive dextran/poly(ethylene glycol) aqueous two-phase systems. As deduced from the fractionation profiles, microcytic cells constitute a heterogeneous cell population with decreased surface charge properties while. macrocytic cells constitute a homogeneous cell population with behaviour similar to that of the control red blood cells. The specific activity of pyruvate kinase, an age-dependent enzyme, did not change along microcytic red blood cells fractionation profiles, suggesting that such cells have altered ageing properties. However, pyruvate kinase specific activity decreases from the left- to the right-hand side of the fractionation profile of macrocytic red blood cells, indicating that these cells follow the normal ageing process. Bisphosphoglycerate mutase specific activity did not change along the fractionation profile of any cell population under study, thus providing 2,3-bisphosphoglycerate during the life-span of the red blood cells from anaemic patients.

Glucose metabolism in bone marrow cells and granulocytes of adult mice after X-ray (5 Gy) irradiation: relationship to cell functionality

Our experiments focused on the metabolic implications of the residual haemopoietic damage in adult mice given 5 Gy X-rays. Bone marrow cells from irradiated mice exhibited an increase in protein synthesis and a decrease in ATP levels, which could be related to the enhancement of the proliferative activity of haemopoietic precursor cells. However, the kinetic parameters (Vmax and Km) of glucose uptake, the glycolytic flux and the hexose monophosphate (HMP) shunt activity were similar to those found in the control group. On the other hand, a reduction of glucose uptake (Vmax) was found in both resting and stimulated granulocytes from irradiated mice. This reduction was accompanied by a decrease in the glycolytic rate and ATP levels. However, HMP shunt activity was similar in resting granulocytes in both the control and the irradiated mice. The stimulation by PMA produced a significantly higher increase in the activity of the pathway in granulocytes from the irradiated mice and was in accordance with the enhancement of superoxide anion production that has been previously described in these cells.

Oxygenation capacity of hypotonized and crosslinked rat erythrocytes

Rat erythrocytes subjected to hypotonic-isotonic dialysis, or crosslinking with bifunctional reagents (glutaraldehyde and dimethyl suberimidate hydrochloride) show a high percentage of methemoglobin and decreased oxyhemoglobin content which implies a low oxygen carrying capacity. Such modified cells maintain reversible oxygen binding properties although, they present a high hemoglobin oxygen affinity (low P50) and a diminished cooperativity in binding oxygen to hemoglobin (low n). These results suggest a reduced capacity of liberating oxygen to tissues under low PO2. Changes produced in erythrocytes can not be restored even in the presence of energy (ATP), reduced glutathione and 2,3-bisphosphoglyceric acid during the dialysis process or after crosslinking/permeabilizing treatment.

A single partitioning step in aqueous polymer two-phase systems reduces hypotonized rat erythrocyte heterogeneity

Rat carrier erythrocytes prepared by hypotonic dialysis (80 mOsm/kg) are a heterogeneous cell population that can be fractionated into two well-defined cell subpopulations by a single partition step, in charge-sensitive dextran-poly(ethylene glycol) aqueous two-phase systems. One subpopulation (65% of total cells) has a decreased cell surface charge and is partitioned at the interface in a single step and then fractionated by counter-current distribution as a low-G subpopulation. The other subpopulation (35% of total cells) has charge surface properties more like those of the untreated control rat erythrocytes. These last cells are partitioned in the top phase in a single step and then fractionated by counter-current distribution as a high-G subpopulation. Partitioning is more effective in reducing cell heterogeneity in hypotonized rat erythrocyte populations than is density separation in Ficoll-paque which only separates a small less dense cell subpopulation (5% of total cells), with the most fragile cells, from a larger and more dense cell subpopulation (95% of total cells), with a mixture of fragile and normal cells. This simple cell separation procedure quickly reduces carrier erythrocyte heterogeneity in a single partitioning step so it can be used to prepare cells for in vivo studies.

Heterogeneity of hypotonically loaded rat erythrocyte populations as detected by counter-current distribution in aqueous polymer two-phase systems

Carrier rat erythrocytes loaded with exogenous substances ([125I] carbonic anhydrase) by hypotonic-isotonic dialysis become heterogeneous cell populations that can be fractionated using the counter-current distribution (CCD) technique. Two well-defined low- and high-partition ratio, G, subpopulations are obtained in charge-sensitive dextran-polyethylene glycol two-phase systems. The low-G subpopulation, which contains the most fragile and surface-altered cells, as deduced from their osmotic fragility curves and partition behaviour, respectively, presents a high amount of exogenous substance incorporated (134.6 cpm/10(6) cells). The high-G subpopulation, that contains cells similar to the control or isotonically dialyzed cells presents a lower amount of exogenous substance incorporated (69.8 cpm/10(6) cells). Cells in this high-G subpopulation seem to be fractionated, like the controls, according to ageing as suggested by the decline of the pyruvate kinase specific activity from the left- to the right-hand side of the CCD profile.

Surface properties of crosslinked erythrocytes as studied by counter-current distribution in aqueous polymer two-phase systems

The bifunctional imidoester dimethyl suberimidate hydrochloride can stabilize rat red blood cells (RBCs) by membrane protein crosslinking, and in that way they can be used as carrier systems for exogenous substances. Counter-current distribution fractionation in charge-sensitive dextran-polyethyleneglycol two-phase systems has been used to detect slight changes in surface charge in stabilized cells. A decrease in the surface charge of crosslinked RBCs and an apparent masking of the age-related cell surface properties have been found to result from the protein crosslinking. Digitonin treatment used to permeabilize crosslinked RBCs produces a significant decrease of the cell surface charge while the age-related surface properties do not seem to be modified by the treatment.

Transferrin binding capacity as a marker of differentiation and maturation of rat erythroid cells fractionated by counter current distribution in aqueous polymer two-phase systems

Rat bone marrow cell populations, containing different proportions of erythroid cells, have been fractionated by counter-current distribution in the non-charge-sensitive dextran/polyethyleneglycol two-phase systems on the basis of hydrophobic cell surface properties. Cell fractions with a low distribution coefficient, which contain non-erythroid cells and early erythoblasts, showed a low transferrin binding capacity and a low haemoglobin/cell ratio whereas cell fractions with a high distribution coefficient, which contain intermediate-late erythroblasts and mature red cells, showed an elevated transferrin binding capacity and the highest haemoglobin/cell ratio. These results support transferrin binding capacity as a good marker parameter for the erythroid bone marrow cell differentiation and maturation processes.

Biochemical characterization of human erythrocytes fractionated by counter-current distribution in aqueous polymer two-phase systems

The fractionation of normal human erythrocytes by counter-current distribution (CCD) in charge-sensitive dextran-polyethylene glycol two-phase systems was confirmed and extended to red blood cells from heterozygous beta-thalassaemic patients. The differences between the distribution profiles of normal (homogeneous) and abnormal (heterogeneous) red blood cells reflect their different surface-charge properties. As suggested by the decline of membrane sialic acid released after neuraminidase treatment and the specific activities of two age-dependent enzymes (membrane acetylcholinesterase and intracellular pyruvate kinase) in the distribution profiles (from the left- to the right-hand side fractions), the fractionation seems to be according to red blood cell age. A constancy of the 2,3-bisphosphoglycerate level was observed in ageing red blood cells.

Transferrin-binding capacity by rat bone marrow populations containing different proportions of erythroid cells

The transferrin-binding capacity of rat bone marrow cells and different erythroid-enriched populations from rat bone marrow has been studied and compared with that previously reported for pure reticulocyte populations. Two components with different transferrin-binding capacities were found. The one with higher affinity was present mainly in erythroid cells and showed an association constant similar to that observed in reticulocyte populations. The component with a lower transferrin affinity was observed mainly in bone marrow fractions containing low proportions of erythroid cells.

Surface properties of crosslinked and crosslinked-permeabilized erythrocytes as studied by partitioning in aqueous polymer two-phase systems

Non-charge- and charge-sensitive dextran/polyethyleneglycol two-phase systems have been used to study the surface properties of red blood cells stabilized by crosslinking with dimethyl suberimidate and permeabilized with digitonin. While crosslinked red blood cells show similar hydrophobic- and charge-related surface properties as control cells, the digitonin treatment changes their surface properties. The changes in hydrophobicity are related to the cell total lipid and cholesterol content while the changes in the charge are related to the sialic acid released by neuraminidase.

Mechanisms towards compensation of long-term haemopoietic injury in mice after 5 Gy irradiation: in vivo and in vitro enhancement of superoxide anion production by granulocytes

This paper analyzes the long-term (6 and 12 months) function of mouse granulocytes after total body irradiation with a single dose (5 Gy) of X-rays. Superoxide anion production has been investigated in granulocytes from peripheral blood, and also in those harvested from long term bone marrow cultures, with the aim of correlating the environmental damage induced by radiation with the functional properties of granulocytes. An in vivo and in vitro enhancement of superoxide anion production and protein levels in granulocytes from irradiated mice is described. The presence of some colony stimulating factor in the supernatant of cultures from irradiated mice could play an important role in the priming of granulocytes.

Rat bone marrow erythroid cell fractionation by counter current distribution in non-charge-sensitive two-phase systems

Counter-current distribution in non charge-sensitive aqueous poly(ethylene glycol)-dextran two phase systems allows the fractionation of rat bone marrow cells into two broad cell subpopulations with different distribution coefficients in a relatively short time. Morphological identification and enzymatic studies suggest that erythroid cells are mainly present in the subpopulation with the higher distribution coefficient. The distribution coefficient and, therefore, surface hydrophobicity of these cells, apparently increase in parallel with an increase in their degree of differentiation and maturation.

Ligand-receptor interactions in affinity cell partitioning. Studies with transferrin covalently linked to monomethoxypoly(ethylene glycol) and rat reticulocytes

The partitioning of rat reticulocytes in poly(ethylene glycol) (PEG)-dextran two-phase systems increases into the PEG-rich top phase when the cells are incubated with transferrin covalently modified with monomethoxy-PEG (MPEG-transferrin) prior to partitioning. Two observations support the suggestion that such an increase in top-phase partitioning is due to the specific interaction of the MPEG-transferrin conjugate with the transferrin receptor on the surface of the reticulocyte: first, the MPEG-transferrin conjugate competes with [125I]transferrin for the transferrin receptor on reticulocytes (Ka = 6.28 x 10(6) l mol-1); and second, the MPEG-modified transferrin is unable to change the partitioning of rat erythrocytes, cells lacking the transferrin receptor. This example illustrates the feasibility of manipulating the partitioning of a selected cell population when ligand-receptor interactions are exploited. The increase in the partitioning of the reticulocytes takes place within a narrow range of MPEG-transferrin bound per cell, viz., 10.2-11.3 fg per cell. The latter range corresponds to ca. 80,000-89,000 molecules of MPEG-transferrin bound per cell.

Transferrin binding of bone marrow cells and metabolic activity of erythrocytes after 5 Gy irradiation

The effect of total body irradiation (5 Gy) on functional mouse erythroid lineage has been studied. The transferrin binding capacity by bone marrow cells and the activity of glycolytic regulatory enzymes and intracellular levels of 2,3 bisphosphoglycerate in peripheral blood erythrocytes have been determined. Results obtained along one year post-irradiation period suggest a complete recovery in the erythroid cell lineage with respect to the biological endpoints investigated.

Settling-time dependence of rat bone marrow cell partition and counter-current distribution in charge-sensitive aqueous two-phase systems. Relationship with the cell partitioning mechanism

Differences in the settling-time dependence of single and multiple cell partitions have been found between heterogeneous (bone marrow cells) and homogeneous (erythrocytes) populations when using charge-sensitive dextran-poly(ethylene glycol) aqueous two-phase systems. The cell populations were partitioned using both single test-tube experiments and multiple thin-layer counter-current distribution. Lengthening the settling time, to favour phase separation, and decreasing the upper phase volume are more effective in fractionation by the counter-current distribution of heterogeneous cell populations than increasing the interfacial tension, although all three were employed to speed phase settling. On the basis of these results, the original cell partitioning mechanism proposed for non-charge-sensitive systems has been extended to charge-sensitive systems.

Analysis by partitioning in aqueous two-phase systems of the loss of transferrin-binding capacity during maturation of rat reticulocytes

A decrease in the number of binding sites for 125I-transferrin, without an apparent modification of the association constant, has been observed during the maturation of reticulocytes into erythrocytes. As an experimental model, different red cell populations from phenylhydrazinic anaemic rates (95% to 12% reticulocyte-rich) have been used. The fractionation by multiple partition in two-phase systems of these red cell populations has been applied here to show the relationship between number of transferrin receptors and rate of reticulocyte maturation.

Metastatic Serratia marcescens endophthalmitis

Metastatic endophthalmitis in a ten-day-old baby who underwent colostomy for an unperforated anus and developed septicemia to Serratia marcescens is described. Although rapid isolation of the agent enabled efficacious specific antibiotic treatment and systemic eradication of the infective agent, the ocular condition continued to deteriorate. Because of the total loss of visual functions and the fear of possible development of sympathetic ophthalmia, enucleation rather than vitrectomy or evisceration was performed. Histopathologic examination of the globe revealed massive infiltrates within the choroid and optic nerve with total destruction of the retinal architecture. The child recovered immediately after surgery and was discharged a week later.

Partitioning behaviour of rat bone marrow cells in aqueous two-phase systems. Dependence of cell partition on the interfacial tension and electrical potential difference between the phases

The partitioning of heterogeneous cell populations of rat bone marrow, in comparison with that of homogeneous populations of erythrocytes, has been studied in aqueous two-phase systems containing increasing concentrations of dextran-poly-(ethylene glycol) (to increase the interfacial tension) and/or decreasing phosphate concentrations (to decrease both the electrical potential difference between the phases and the interfacial tension). At any polymer and/or phosphate concentration tested the partition is lower for bone marrow cells, reflecting their lower surface charge and hydrophobicity.

Fractionation of bone-marrow cells by counter-current distribution in aqueous polymer two-phase systems. Relation between settling time and the efficiency of separation

The fractionation of heterogeneous populations of rat and human bone-marrow cells has been studied by counter-current distribution in a charged 5% dextran-4% poly(ethylene glycol) two-phase system. The subfractionation into two broad populations has been achieved at a low top/bottom phase volume ratio by increasing (up to 20 min) the settling time allowed for the phases to be separated after each mixing step. No effect of this parameter on a homogeneous population of erythrocytes has been observed. However, heterogeneous cell separations can be improved by exploiting different phase settling times.