Genotype analysis to clarify RhD variants in discrepant samples of Chilean population

Introduction

The D antigen variants are classified as weak, partial, and extremely weak (DEL) and can be differentiated using molecular tests. In Chile, the laboratories of local blood centers do not identify variants of the D antigen, referring them for study to the Reference Laboratory of the Public Health Institute of Chile. So, our aim was to talk about the results of the molecular analysis of variants of the D antigen in samples that had different results in the serological classification.

Methods

In the D antigen classification of the Rh system, 479 samples with serological discrepant results were sent for molecular analysis. The Rh phenotype was performed with monoclonal anti-C, anti-c, anti-E, and anti-e antisera by direct agglutination. To find the D antigen, researchers used direct agglutination with monoclonal antisera and indirect antiglobulin testing with the column (gel) agglutination method. Molecular analysis was performed with a polymerase chain reaction with sequence-specific primers (SSP-PCR) and sequencing.

Results and discussion

The presence of D antigen variants was confirmed in 332 samples (69.3%), with an initial discrepancy in serological classification. In this group of discrepant samples, the frequency of weak RhD variants was 66% (219/332), that of extremely weak RhD was 28% (93/332), and that of partial RhD was 6% (20/332). The weak variants type 2 (27.4%), type 3 (8.4%), type 48 (8.4%), and type 1 (8.1%) were the next most prevalent variants after RHD*DEL43 (28%). The ccEe (R2r) phenotype was the most frequently detected (38.4%) and is present in 87% of the RHD*DEL43 samples. The E antigen is associated with the presence of this variant. Our analyses give the first description of D antigen variants in Chile. The most common variants are DEL type (RHD*DEL43) and weak (weak type 2), which are linked to the ccDEe (R2r) phenotype. These findings allow us to characterize the variants of the D antigen in Chile and, according to the obtained data, to design strategies for the management of donors, patients, and pregnant women.

The insula mediates the effects of glucocorticoids in anxiety

Increased activity in the insula has been consistently reported to be associated with anxiety and anxiety-related disorders. However, little is known on how the insula regulates anxiety. The present study aims at determining the role of the insula on the effects of glucocorticoids in anxiety. A combination of pharmacological manipulations, including blockade of adrenal GC synthesis by metyrapone and intra-insular microinjections of corticosterone, corticosterone-BSA, mineralocorticoid receptor (MR) antagonist spironolactone and glucocorticoid receptor (GR) antagonist mifepristone, were used to assess the short-term (5 min) effects of intra-insular corticosterone in two anxiety-like behaviors in male Sprague-Dawley rats. The elevated plus maze (EPM) and Novelty Suppressed Feeding (hyponeophagia) were utilized. We found that corticosterone in the insula is sufficient to prevent the anxiolytic effects corticosterone synthesis blockade in anxiety, and that intra-insular corticosterone has anxiolytic or anxiogenic effects depending on the amount of corticosterone microinjected, without affecting the HPA axis. Glucocorticoid anxiolytic effects in the insula are mediated by MRs, while its anxiogenic effects are dependent on a mifepristone-sensitive membrane-bound mechanism. Anxiety appears to be modulated at the insula through a competition between fast MR-dependent anxiolytic and membrane-associated mifepristone-sensitive anxiogenic signaling pathways that orchestrate the behavioral response to stress and determines the resulting level of anxiety.

KI04 an Aminoglycosides-Derived Molecule Acts as an Inhibitor of Human Connexin46 Hemichannels Expressed in HeLa Cells

BACKGROUND

Connexins (Cxs) are proteins that help cells to communicate with the extracellular media and with the cytoplasm of neighboring cells. Despite their importance in several human physiological and pathological conditions, their pharmacology is very poor. In the last decade, some molecules derived from aminoglycosides have been developed as inhibitors of Cxs hemichannels. However, these studies have been performed in E. coli, which is a very simple model. Therefore, our main goal is to test whether these molecules have similar effects in mammalian cells.

METHODS

We transfected HeLa cells with the human Cx46tGFP and characterized the effect of a kanamycin-derived molecule (KI04) on Cx46 hemichannel activity by time-lapse recordings, changes in phosphorylation by Western blot, localization by epifluorescence, and possible binding sites by molecular dynamics (MD).

RESULTS

We observed that kanamycin and KI04 were the most potent inhibitors of Cx46 hemichannels among several aminoglycosides, presenting an IC50 close to 10 μM. The inhibitory effect was not associated with changes in Cx46 electrophoretic mobility or its intracellular localization. Interestingly, 5 mM DTT did not reverse KI04 inhibition, but the KI04 effect completely disappeared after washing out KI04 from the recording media. MD analysis revealed two putative binding sites of KI04 in the Cx46 hemichannel.

RESULTS

These results demonstrate that KI04 could be used as a Cx46 inhibitor and could help to develop future selective Cx46 inhibitors.

GABAergic Regulation of Astroglial Gliotransmission through Cx43 Hemichannels

Gamma-Aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the brain. It is produced by interneurons and recycled by astrocytes. In neurons, GABA activates the influx of Cl- via the GABAA receptor or efflux or K+ via the GABAB receptor, inducing hyperpolarization and synaptic inhibition. In astrocytes, the activation of both GABAA and GABAB receptors induces an increase in intracellular Ca2+ and the release of glutamate and ATP. Connexin 43 (Cx43) hemichannels are among the main Ca2+-dependent cellular mechanisms for the astroglial release of glutamate and ATP. However, no study has evaluated the effect of GABA on astroglial Cx43 hemichannel activity and Cx43 hemichannel-mediated gliotransmission. Here we assessed the effects of GABA on Cx43 hemichannel activity in DI NCT1 rat astrocytes and hippocampal brain slices. We found that GABA induces a Ca2+-dependent increase in Cx43 hemichannel activity in astrocytes mediated by the GABAA receptor, as it was blunted by the GABAA receptor antagonist bicuculline but unaffected by GABAB receptor antagonist CGP55845. Moreover, GABA induced the Cx43 hemichannel-dependent release of glutamate and ATP, which was also prevented by bicuculline, but unaffected by CGP. Gliotransmission in response to GABA was also unaffected by pannexin 1 channel blockade. These results are discussed in terms of the possible role of astroglial Cx43 hemichannel-mediated glutamate and ATP release in regulating the excitatory/inhibitory balance in the brain and their possible contribution to psychiatric disorders.

Prenatal fluoxetine impairs non-hippocampal but not hippocampal memory in adult male rat offspring

Fluoxetine is often prescribed to treat depression during pregnancy. Rodent studies have shown that fluoxetine exposure during early development can induce persistent changes in the emotional behavior of the offspring. However, the effects of prenatal fluoxetine on memory have not been elucidated. This study evaluates the memory of adult male offspring from rat dams orally administered with a clinically relevant dose of 0.7 mg/kg fluoxetine from 9 weeks before pregnancy to 1 week before delivery. Hippocampal-dependent (Morris Water Maze, MWM) and non-hippocampal-dependent (Novel Object Recognition, NOR) memory paradigms were assessed. Anxiety- and depressive-like symptoms were also evaluated using the Open Field Test, Tail Suspension Test and Sucrose Preference Test. Male rats exposed to fluoxetine during gestation displayed NOR memory impairments during adulthood, as well as increased anxiety- and depressive-like symptoms. In the MWM, the offspring of fluoxetine-treated dams did not show learning deficits. However, a retention impairment was found on remote memory, 15 days after the end of training. Molecular analyses showed increased expression of NMDA subunit NR_2B, and a decrease in NR_2A-to- NR_2B ratio in the temporal cortex, but not in the hippocampus, suggesting changes in NMDA receptor composition. These results suggest that in utero exposure to fluoxetine induces detrimental effects on non-hippocampal memory and in remote retention of hippocampal-dependent memory, which is believed to be stored in the temporal cortex, possibly due to changes in cortical NMDA receptor subunit stoichiometry. The present results warrant the need for studies on potential remote memory deficits in human offspring exposed to fluoxetine in utero.

4-Hydroxynonenal induces Cx46 hemichannel inhibition through its carbonylation

Hemichannels formed by connexins mediate the exchange of ions and signaling molecules between the cytoplasm and the extracellular milieu. Under physiological conditions hemichannels have a low open probability, but in certain pathologies their open probability increases, which can result in cell damage. Pathological conditions are characterized by the production of a number of proinflammatory molecules, including 4-hydroxynonenal (4-HNE), one of the most common lipid peroxides produced in response to inflammation and oxidative stress. The aim of this work was to evaluate whether 4-HNE modulates the activity of Cx46 hemichannels. We found that 4-HNE (100 μM) reduced the rate of 4',6-diamino-2-fenilindol (DAPI) uptake through hemichannels formed by recombinant human Cx46 fused to green fluorescent protein, an inhibition that was reversed partially by 10 mM dithiothreitol. Immunoblot analysis showed that the recombinant Cx46 expressed in HeLa cells becomes carbonylated after exposure to 4-HNE, and that 10 mM dithiothreitol reduced its carbonylation. We also found that Cx46 was carbonylated by 4-HNE in the lens of a selenite-induced cataract animal model. The exposure to 100 μM 4-HNE decreased hemichannel currents formed by recombinant rat Cx46 in Xenopus laevis oocytes. This inhibition also occurred in a mutant expressing only the extracellular loop cysteines, suggesting that other Cys are not responsible for the hemichannel inhibition by carbonylation. This work demonstrates for the first time that Cx46 is post-translationally modified by a lipid peroxide and that this modification reduces Cx46 hemichannel activity.

P0938HEALTH-RELATED QUALITY OF LIFE IN A CHILEAN POPULATION OF DIALYSIS PATIENTS

Background and Aims

A growing number of patients treated with maintenance dialysis are older, frail and have functional impairment. In many instances, functional impairment is a more powerful predictor of adverse outcomes than traditional disease-based measures. The Kidney Disease Quality of Life 36-item short form survey (KDQOL-36) is widely used in dialysis patients; its scores are important predictor of outcome. Aim of the study is to evaluate the associations of KDQOL-36 scores with diabetes, dialysis modality, nutritional status and age in a cohort of dialysis patients from Chile.

Method

observational, multicenter, cross-sectional study performed in the region of Valparaiso, Chile. 207 adult patients on dialysis from more than 3 months (140 in HD, 67 in PD: mean age 58.9 ± 14.5 years with 37% >= 65 years, M/F 119/88) were asked to fill in the Spanish translation of the KDQOL-36 questionnaire (administered by a trained caregiver). The responses to the SF-36 questions were used to determine scores for the mental component summary (MCS), physical component summary (PCS), burden of kidney disease (BKD), symptoms and problems of kidney disease (SPKD), effects of kidney disease (EKD). The scores went from 0 to 100; the higher scores the better the quality of life. 50 was set as a cut-off level. Nutritional parameters were collected (BMI; mean 27.16 ± 4.7 kg/m2, brachial muscular or fat areas (< 25th percentile for age and sex defined as malnourished). All the patients signed an informed consent.

Results

Overall, mean scores and percentage of patients with values <50 on the PCS, MCS, BKD, SPKD, and EKD subscales were 45.54 ± 18.82 (60.9%), 57.38 ± 19.41 (36.2%), 73.43 ±18.33 (65.2%), 79.03 ±11.59 (1.9%), and 36.02 ± 34.74 (11.6%), respectively. The mean score of the combination of MCS and PCS was 51.46 ± 16.77 (52.2%).

Compared to younger patients, those who were 65 or more years old had significantly higher score of EKD (79.91 ± 16.63 vs 69.59 ± 18.26, p<0.0001), with only 12% of older patients having a score below 50 (Χ2 7.79, p=0.005); the other subscales did not differ significantly.

Ninety-one (43.5%) patients were diabetics. They were more likely of being older, having a higher BMI and lower signs of malnutrition (borderline significance). In comparison to non-diabetics, they had lower mean scores on BKD scale (30.42 ± 35.12 vs 40.4 ± 33.87, p=0.04) with a higher number having BKD scores < 50 (66/91 vs 69/116, Χ2 3.82, p=0.035). Moreover, they were more likely of having scores < 50 for the SPKD and EKD subscales.

A significant reduction of the muscular and fat brachial areas (<25th percentile) were found in 88 (42.1%) and 49 (23.4%) of the patients, respectively. Mean scores of all subscales did not differ significantly between the groups of muscular and fat brachial areas.

The dialysis modality had a significant impact on some subscales. in comparison to PD, a higher number of HD patients had scores < 50 for BKD (Χ2 18.24, p < 0.0001). On the other hand, PD patients were more likely of having lower MNS scores (Χ2 5.69, p < 0.013) and of the combination of PCS and MCS subscales (Χ2 12.82, p < 0.0001). Similar findings were obtained when analysing the scores as continuous variables.

Conclusion

This is the first formal evaluation of the performances of the KDQOL-36 questionnaire in a cohort of dialysis patients in Chile. Overall, the mean scores of PCS and EKD were well below the reference value of 50. General and kidney-related subscales were affected differently by age, dialysis modality and diabetes. In particular diabetic patients were more likely to perform poorly at kidney-related subscales, with no significant difference for general ones. Interestingly, dialysis modality had an impact on both BKD and MCS with opposite trends. The nutritional status seems to little affect patient quality of life.

Anti-HPV Nanoemulsified-Imiquimod: A New and Potent Formulation to Treat Cervical Cancer

Cervical cancer is associated with the human papilloma virus (HPV) and nowadays is the fourth most frequent cancer among women. One of the treatments for this disease is based on the application of imiquimod. In this study, we postulated that the use of imiquimod in nanoemulsion results in a better antitumoral effect than the drug administered in its nonencapsulated form for the treatment of cervical cancer. Permeability studies using vaginal mucosa, as membrane, and in vitro studies involving cervical cancer cells (viability, clonogenic assay, and cell death analysis) were performed. We showed that low amount of encapsulated imiquimod permeated the vaginal mucosa. However, a higher percentage of cells died after the treatment with low amount (3.0 μmol L^-1) of the formulation compared to the free drug. In addition, the innovative formulation presented a combinatory mechanism of cell death involving autophagy and apoptosis. Our results demonstrate that the imiquimod-loaded nanoemulsioncan be an alternative product for the treatment of cervical cancer validating the hypothesis.

Effectiveness and Impact of the Walking Bleach Technique on Esthetic Self-perception and Psychosocial Factors: A Randomized Double-blind Clinical Trial

OBJECTIVE

This trial evaluates the impact of psychosocial and esthetic self-perceptions of patients undergoing nonvital tooth bleaching using the walking bleach technique. We also assessed the clinical effectiveness of bleaching tooth discoloration.

METHODS

Fifty volunteers with nonvital tooth discoloration were enrolled. Teeth were randomized into two groups: 35% hydrogen peroxide (n=25) and 37% carbamide peroxide (n=25). Intracoronal bleaching was performed over four sessions using the walking bleach technique. Tooth color was evaluated at each session to measure total color variation. The shade guide was arranged from highest (B1) to lowest (C4) values to assess the color and calculate the color change in the number of shade guide units. Subjective and objective assessments were compared with the tooth counterpart. Esthetic self-perception and psychosocial factors were assessed before and after treatment.

RESULTS

Color change was 15.48<5.17 for hydrogen peroxide and 14.02<4.85 for carbamide peroxide. There was no significant difference at any time point (p>0.05) except at sessions 3 and 4 (p<0.05). Overall, whitened teeth values were similar to those of counterpart teeth (p>0.05). There was a decrease in Oral Health Impact Profile and Psychosocial Impact of Dental Esthetics questionnaire scores after treatment compared with baseline (p<0.05).

CONCLUSION

The walking bleach technique was highly effective on nonvital teeth and had a positive effect on self-esthetic perception and psychological impact for the patients.

Influence of carbon dioxide stunning procedure on quality of turkey meat

1. The objective of this study was to evaluate the effect of sex and gas stunning on quality attributes of turkey breast meat. 2. One hundred B.U.T. Premium turkeys (50 males and 50 females) were divided into four groups of 25 animals and subjected to one of two CO₂ stunning procedures: G1 stepwise (step 1: 30% CO₂, 15 s; step 2: 55% CO₂, 40 s; step 3: 70% CO₂, 45 s) or G2 fixed concentration (80% CO₂, 100 s). The pH and meat colour at 20 min post-mortem, and pH, colour (L*, a*, b*), water holding capacity (WHC), drip loss (DL), cooking loss (CL) and Warner-Bratzler shear force (WBSF) in breast samples at 24 h and 7 d post-mortem were assessed. 3. There were significant differences between stunning groups for pH, meat colour and CL, whereas no significant differences were found for DL and WBSF. Sex had a significant effect on pH and b* and ageing of meat affected pH, colour coordinates, DL and WBSF. 4. It was concluded that the G2 treatment affected negatively the pH value and colour coordinates. However, G2 stunning affected positively the WHC parameters. Female turkeys had better results than males for pH, and the colour of female turkey breast meat was less yellow than male breast meat.

Gene expression of Vibrio parahaemolyticus growing in laboratory isolation conditions compared to those common in its natural ocean environment

BACKGROUND

Vibrio parahaemolyticus is an autochthonous marine bacterial species comprising strains able to grow in broth containing bile salts at 37 °C, a condition seldom found in the ocean. However, this condition is used for isolation in the laboratory because it is considered a necessary property for pathogenesis. In this context, revealing how gene expression enables V. parahaemolyticus to adapt to this particular condition -common to almost all V. parahaemolyticus isolates- will improve our understanding of the biology of this important pathogen. To determine the genes of V. parahaemolyticus differentially expressed when growing in isolation condition (37 °C, 0.9% NaCl, and 0.04% bile salts) referred to those at the temperature and salt concentration prevailing in ocean south of Chile (marine-like condition; 12 °C, 3% NaCl, and absence of bile salts) we used high-throughput sequencing of RNA.

RESULTS

Our results showed that in the isolation condition, among the 5034 genes annotated in the V. parahaemolyticus RIMD2210633 genome, 344 were upregulated and 433 downregulated referred to the marine-like condition, managing an adjusted P-value (Padj) < E-5. Between the 50 more highly expressed genes, among the small RNAs (sRNA), the three carbon storage regulators B (CsrB) were up four to six times, while RyhB, related to iron metabolism besides motility control, was down about eight times. Among proteins, BfdA, a hemolysin-co-regulated protein (Hcp1) secreted by T6SS1, one of the most highly expressed genes, was about 140 times downregulated in isolation condition. The highest changes in relative expression were found among neighboring genes coding for proteins related to respiration, which were about 40 times upregulated.

CONCLUSIONS

When V. parahaemolyticus is grown in conditions used for laboratory isolation 777 genes are up- or downregulated referred to conditions prevailing in the marine-like condition; the most significantly overrepresented categories among upregulated processes were those related to transport and localization, while secretion and pathogenesis were overrepresented among downregulated genes. Genes with the highest differential expression included the sRNAs CsrB and RhyB and the mRNAs related with secretion, nutritional upshift, respiration and rapid growing.

Carcass and Meat Quality Traits in an Embden×Toulouse Goose Cross Raised in Organic Dehesa

This study assessed the influence of genetic type (Embden-Anser anser, EE; Toulouse-Anser anser, TT and F1 cross, ET) for meat characteristics (carcass, meat quality and fatty acid (FA) profiles), of domestic geese "Anser anser domesticus" raised in dehesa as an alternative, organic feeding system. Carcass and breast muscle weight (p<0.01) were greater for the ET group at the same live weight. None of the groups showed differences in the production of fatty liver with this type of feeding. Higher values were found for maximum Warner-Bratzler shear force (between 7.62 and 8.87 kg/cm(2)), which implies the improvement of this parameter. High levels of oleic FAs were obtained, especially for the TT group. The polyunsaturated/saturated FA ratio was highest for the ET group (p<0.001), reflecting the optimum nutritional values as a component of a healthy consumer diet.

Effects of stress by unfamiliar sounds on carcass and meat traits in bulls from three continental beef cattle breeds at different ageing times

One-hundred-and-twenty-four young bulls of three Continental beef cattle breeds were used to study the effect of pre-slaughter stress by unfamiliar sounds on carcass traits and quality characteristics of beef aged for three different periods. Stress due to unfamiliar noises had a moderately negative effect on carcass and meat quality. Carcasses from group Stressed had higher (P<0.05) values of pH0, pH24, a*, and Warner-Bratzler shear force, and lower (P<0.05) values of L*, b* and pressure losses than from Unstressed animals. There were significant differences (P<0.05) among breeds in L*, a* and pressure losses. The ageing time had a significant effect on chromatic variables, WBSF and pressure losses. The cooking losses were not significantly affected by any of the three factors discussed. These results emphasize the importance of implementing appropriate management practices during pre-slaughter handling of cattle in order to reduce any possible risk factor for stress, as well as the different sensitivity of the breeds to similar stimuli.

Effect of sex and final fattening on ultrasound and carcass traits in Iberian pigs

A hundred and twenty-five castrated Iberian pigs (61 males and 64 females, from 106.9 kg of live weight at star to 160.3 kg at slaughter) was used to investigate the effect of feeding system on carcass attributes (backfat thickness and loin area measured with ultrasound before slaughter, and intramuscular fat and weights and yields of hams, forelegs and loins after slaughter). Pigs were fattened outdoor under extensive conditions. There were 4 treatments: "montanera", M; "recebo", R; "cebo a campo", C; and high oleic fed, O). Ultrasound images were collected at two rib locations (10th and 14th). M and O groups had the highest fat thickness and loin area was lower in M than in C group. M and O showed higher carcass weight and yield than the other groups. The largest ham weight was for C and the lowest for M groups. Loin weight and yield were higher in M and R than the other two groups (O and C).

Amyloid β oligomers decrease hippocampal spontaneous network activity in an age-dependent manner

Soluble amyloid beta (Abeta) oligomers might trigger early cognitive impairment in Alzheimer's Disease (AD) through the impairment of proper neuronal network function. We have recently shown that the short sequence Abeta(25-35) affects the spontaneous activity in hippocampal slices, when was added to the bath, at high nanomolar concentrations. In the present study, we aimed to characterize the effects of the oligomerized full length sequence Abeta(1-42) on the spontaneous network activity in the CA1 hippocampal area testing whether such effects are age dependent. By performing extracellular field recordings of spontaneous network activity of hippocampal slices, we found that an oligomerized solution of Abeta(1-42) (osAbeta) potently inhibit, in a dose-dependent manner, the spontaneous hippocampal network activity with an IC(50) of 0.4 +/- 3.2 nM and a maximal effect reached around 10 nM. While spontaneous hippocampal network activity is unaffected by age, the sensitivity of spontaneous hippocampal network activity to osAbeta (10 nM) appears to be increased in slices from older animals. Moreover, to see a significant reduction in spontaneous network activity in slices from animals in their second week of life 100nM osAbeta was needed. The osAbeta-induced reduction in hippocampal network activity is accompanied by a presynaptic reduction in both spontaneous and miniature synaptic potentials. Finally, we demonstrated that the effect produced by osAbeta on spontaneous network activity was specific, reversible and unrelated with cell death. In conclusion, our data show that osAbeta alters hippocampal network activity at concentrations commonly observed in AD patients and that such effect of osAbeta increase with age.

The role of PET-CT in the follow-up of patients with urothelial cancer diagnosis

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Background: Positron emission tomography (PET) is an imaging technique whose principle is the detection of metabolic activity of tumor cells but in urology its use had been restricted due to urinary excretion of the radiotracer and overlap with urological structures, the use of hybrid PET (PET-CT) would allow its use for monitoring patients with urothelial tumors.

Methods: Between 2007 and 2010 we performed PET-TC images in consecutive patients with suspected recurrences in CT scan or MRI. All patients had renal, bladder and uretral cancer and were treated with urothelial cancer diagnosis. We evaluate the usefulness of FDG PET-CT and its impact on behavior therapy in suspected recurrence in patients with urothelial carcinoma, compared with conventional studies.

Results: 17 patients were studied for suspected recurrence. All patients had positive images previously on CT scan and MRI; positive PET-TC was observed in 14 and 3 studies were negative. The positive PET-CT showed more number of lesions and change the medical and surgical strategy. Of the three studies negative on PET- CT none had recurrence and remain disease free. PET/CT is in a great benefit to the detection recurrence in the follow up of patients with urothelial cancer diagnosis. These results showed an increased sensitivity and specificity over previous work with conventional PET technology. In the series studied, the implementation of PET-CT (FDG) in the follow up of patients with urothelial tumors were an useful tool.

Conclusions: PET/CT is in a great benefit to the detection recurrence in the follow up of patients with urothelial cancer diagnosis. These results showed an increased sensitivity and specificity over previous work with conventional PET technology. In the series studied, the implementation of PET-CT (FDG) in the follow up of patients with urothelial tumors were an useful tool. However, multicenter studies and more patients are required to define its role.

No significant financial relationships to disclose.

Organotypic cultures as tool to test long-term effects of chemicals on the nervous system

The study of neuroscience has vastly benefited from the use of brain slices. This preparation has been fundamental for the understanding of the cellular basis of nervous system function as well as for the study of the mechanisms involved in neuronal network dysfunction. This experimental model provides flexible access, and control of, specific neural circuits and maintains their basic properties, allowing them to reproduce most of their natural network activities. Brain slices permit the combination of sophisticated techniques such as electrophysiology, fluorescence imaging, pharmacology, molecular biology, etc. More recently, the development of organotypic brain slice cultures has expanded the use of modern technical approaches to the study neuronal networks, while increasing their possibilities of evaluating long-term effects of acute experimental conditions, as well as the effects of chronic treatments on neuronal network function in vitro. Here, I will provide an overview of the use of organotypic cultures to understand neuronal network function and dysfunction, as well as the pharmacological approaches used for these studies. As a final example, I will review the studies performed in organotypic cultures regarding the deleterious effects of long-term amyloid beta application on neuronal networks in vitro, as well as the use of drugs that may prevent or revert their deleterious effects on nervous system function. Overall, this review will provide elements to support the use of organotypic cultures as a very reliable model to explore long-term neuropharmacological studies in vitro.

Características de la canal de cabritos de las razas Criollo cordobés y Anglo nubiana. Efecto de la edad al sacrificio

Se estudiaron las características de la canal de cabritos lactantes de las razas Criollo Cordobés y Anglo Nubiana, utilizando 20 machos de cada raza. Los animales se sacrificaron a dos edades: 60±2 días (grupo I) y 90±3 días (grupo II). Los rendimientos canal y el grado de engrasamiento fueron superiores en Anglo Nubiana. La raza y la edad al sacrificio tuvieron un efecto significativo en la valoración subjetiva, en las medidas e índices de la canal y en el quinto cuarto.

Calcium-activated potassium currents differentially modulate respiratory rhythm generation

The pre-Bötzinger complex (PBC) generates eupnea and sighs in normoxia and gasping during hypoxia through particular mixtures of intrinsic and synaptic properties. Among intrinsic properties, little is known about the role of Ca(2+)-activated potassium channels in respiratory rhythms generation. To examine this role, we tested the effects of openers and blockers of the large-conductance (BK) and small-conductance (SK) Ca(2+)-activated potassium channels on the respiratory rhythms recorded both in vitro and in vivo, as well as on the discharge pattern of respiratory neurons in the PBC. Activation of SK channels with 1-ethyl-2-benzimidazolinone (1-EBIO) abolished sigh-like activity and inhibited eupneic-like activity, whereas blockade of SK channels with apamine (APA) increased frequency in both rhythms. In hypoxia, APA did not affect the transition to gasping-like activity. At the cellular level, activation of SK channels abolished pacemaker activity and decreased non-pacemaker neurons discharge; opposite effects were observed with SK blockade. In contrast to SK channel modulation, either activation or blockade of BK channels with NS 1619 or iberiotoxin and paxilline, respectively, produced mild effects on eupneic-like and sigh-like bursts during normoxia in vitro. However, BK blockers prevented the changes associated with the transition to gasping-like activity in vitro and perturbed gasping generation and autoresuscitation in vivo. At the cellular level BK channel modulation did not affect respiratory neurons discharge. We conclude that K(Ca) participate in rhythm generation in a state-dependent manner; SK channels are preferentially involved in rhythm generation in normoxia whereas BK channels participate in the transition to gasping generation in hypoxia.

Laboratory rearing conditions for improved growth of juvenile Helix aspersa Müller snails

A laboratory rearing system in semi-controlled conditions is proposed to facilitate the behavioural rhythms of the edible snail (Helix aspersa) and to produce a high growth rate with low variability. The growth data were used to construct a model for weight estimation based on age. The animals' live weights showed low variability (<17%) and normal distribution. The best model for estimating weight from age is the logistic model, with a high corelation coefficient (>90%), and a high level of significance for the coefficient (P < 0.0001).

The role of beta-amyloid protein in synaptic function: implications for Alzheimer's disease therapy

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive and irreversible loss of memory and other cognitive functions. Substantial evidence based on genetic, neuropathological and biochemical data has established the central role of beta-amyloid protein (betaAP) in this pathology. Although the precise etiology of AD is not well understood yet, strong evidence for some of the molecular events that lead to progressive brain dysfunction and neurodegeneration in AD has been afforded by identification of biochemical pathways implicated in the generation of betaAP, development of transgenic models exhibiting progressive disease pathology and by data on the effects of betaAP at the neuronal network level. However, the mechanisms by which betaAP causes cognitive decline have not been determined, nor is it clear if the degree of dementia correlates in time with the degree of neuronal loss. Hence, it is of interest to understand the biochemical processes involved in the mechanisms of betaAP-induced neurotoxicity and the mechanisms involved in electrophysiological effects of this protein on different parameters of synaptic transmission and on neuronal firing properties. In this review we analyze recent evidence suggesting a complex role of betaAP in the molecular events that lead to progressive loss of function and eventually to neurodegeneration in AD as well as the therapeutic implications based on betaAP metabolism inhibition.

Combining headspace gas chromatography with mass spectrometry detection for confirmation of hydrocarbon residues in virgin olive oil following automatic screening

Hydrocarbon residues can be present in virgin olive oils either naturally or as contaminants. Presence of benzene, toluene, ethylbenzene, xylene isomers and styrene (BTEXS) in virgin olive oil, demanded the establishment of a cut-off level to discriminate oil samples containing these residues at normal levels from those at high levels caused by contamination. By introducing volatile components present in the headspace (HS) of the oil samples (without prior chromatographic separation) into the ionization source of a mass spectrometer, samples were classified as containing normal or high levels of BTEXS (recommendable or non-recommendable forhuman consumption). Confirmation and quantification of contaminated virgin olive oils were achieved by combining HS sampling with gas chromatography-mass spectrometry (GC-MS). No sample pretreatment was necessary for the chromatographic method, but the addition of 600 microl of ethyl acetate as chemical modifier for 10 ml of virgin olive oil. Detection limits ranged between 3 and 9 ng/ml. Oil analysis showed the presence of toluene in all samples, as well as the absence of benzene, ethylbenzene and o-xylene.

Methylene blue-photoinactivated plasma vs. fresh-frozen plasma as replacement fluid for plasma exchange in thrombotic thrombocytopenic purpura

BACKGROUND AND OBJECTIVES

Plasma exchange with fresh-frozen plasma (FFP) is the treatment of choice in thrombotic thrombocytopenic purpura (TTP). Methylene blue-photoinactivated plasma (MBPIP) has been proposed as a safer alternative to FFP, but its effectiveness in the treatment of TTP is not well established. The purpose of this study was to investigate whether MBPIP is as effective as FFP in the treatment of TTP by plasma exchange.

MATERIALS AND METHODS

A retrospective analysis was carried out of 56 TTP episodes, occurring between 1990 and 2003, which had been treated by plasma exchange. MBPIP was used for fluid replacement in 27 episodes and FFP in 29. The effect of plasma (MBPIP or FFP) on treatment outcomes was analysed by multivariate logistic regression.

RESULTS

Compared to patients treated with FFP, those receiving MBPIP had an increased risk of dying from progressive TTP [adjusted odds ratio (OR) = 31; 95% confidence interval (CI): 1.2 to > 100], a greater number of recurrences while on plasma exchange therapy (OR = 4.6; 95% CI: 1.2-17), and a lower probability of attaining a sustained remission within 9 days of starting plasma exchange (OR = 5.2; 95% CI: 1.3-20).

CONCLUSIONS

MBPIP seems to be less effective than FFP in the treatment of TTP. It is therefore prudent to avoid MBPIP until therapeutic equivalency to FFP has been established by randomized, controlled trials.

Paired pulse facilitation is turned into paired pulse depression in hippocampal slices after epilepsy induced by 4-aminopyridine in vivo

Modifications in synaptic plasticity seem to play a key role in the origin and persistence of epilepsy. 4-Aminopyridine (4-AP) induces intense and long lasting epileptic seizures and neurodegeneration when applied into the hippocampus in vivo, effects that seem to be mediated by overactivation of glutamate receptors due to the enhancement of glutamate release from nerve endings. We have studied presynaptic modifications of CA1 responses, using the paired pulse paradigm, in hippocampal slices obtained from 4-AP-treated rats killed during epileptic activity (ex vivo). The paired pulse facilitation (PPF) observed in control slices with interstimulus intervals of 10-30 ms was changed into paired pulse depression (PPD) after 100 microM 4-AP added in vitro. A strikingly similar change was observed in the ex vivo slices even though 4-AP was no longer present in the tissue. We conclude that the facilitation of glutamate release induced by 4-AP becomes chronic after a transient exposure to the drug. This suggests that the facilitated neurotransmitter release induced by 4-AP triggers a more permanent plastic change that may be responsible for the persistence of epilepsy.

Effect of vulvomucosal injection of D-cloprostenol at weaning and at insemination on reproductive performance of sows during the low fertility summer season under field conditions

The aim of this study was to evaluate the hypothesis that the intravulvar injection of a PGF2alpha analogue at weaning just prior to insemination may minimise the effects of summer infertility in pigs. From July to September 1999, two groups of 30 sows were randomly formed each month. The experimental group comprised sows receiving 37.5 microg of a PGF2alpha analogue, D-cloprostenol, in 0.5 ml injected into the vulvar lips at weaning and at insemination. Group 2 sows received 0.5 ml of saline solution injected into the vulvar lips and served as controls. The percentage of sows in oestrus within 7 days after weaning in treated sows was 27.93% higher than in controls (P<0.001). Fertility for treated sows was also significantly increased by the treatment (P<0.01). However, neither the percentage of inseminated sows that farrowed nor litter size was affected by treatment.

Seizures and neurodegeneration induced by 4-aminopyridine in rat hippocampus in vivo: role of glutamate- and GABA-mediated neurotransmission and of ion channels

Infusion of the K(+) channel blocker 4-aminopyridine in the hippocampus induces the release of glutamate, as well as seizures and neurodegeneration. Since an imbalance between excitation and inhibition, as well as alterations of ion channels, may be involved in these effects of 4-aminopyridine, we have studied whether they are modified by drugs that block glutamatergic transmission or ion channels, or drugs that potentiate GABA-mediated transmission. The drugs were administered to anesthetized rats subjected to intrahippocampal infusion of 4-aminopyridine through microdialysis probes, with simultaneous collection of dialysis perfusates and recording of the electroencephalogram, and subsequent histological analysis. Ionotropic glutamate receptor antagonists clearly diminished the intensity of seizures and prevented the neuronal damage, but did not alter substantially the enhancement of extracellular glutamate induced by 4-aminopyridine. None of the drugs facilitating GABA-mediated transmission, including uptake blockers, GABA-transaminase inhibitors and agonists of the A-type receptor, was able to reduce the glutamate release, seizures or neuronal damage produced by 4-aminopyridine. In contrast, nipecotate, which notably increased extracellular levels of the amino acid, potentiated the intensity of seizures and the neurodegeneration. GABA(A) receptor antagonists partially reduced the extracellular accumulation of glutamate induced by 4-aminopyridine, but did not exert any protective action. Tetrodotoxin largely prevented the increase of extracellular glutamate, the electroencephalographic epileptic discharges and the neuronal death in the CA1 and CA3 hippocampal regions. Valproate and carbamazepine, also Na(+) channel blockers that possess general anticonvulsant action, failed to modify the three effects of 4-aminopyridine studied. The N-type Ca(2+) channel blocker omega-conotoxin, the K(+) channel opener diazoxide, and the non-specific ion channel blocker riluzole diminished the enhancement of extracellular glutamate and slightly protected against the neurodegeneration. However, the two former compounds did not antagonize the 4-aminopyridine-induced epileptiform discharges, and riluzole instead markedly increased the intensity and duration of the disharges. Moreover, at the highest dose tested (8mg/kg, i.p.), riluzole caused a 75% mortality of the rats. We conclude that 4-aminopyridine stimulates the release of glutamate from nerve endings and that the resultant augmented extracellular glutamate is directly related to the neurodegeneration and is involved in the generation of epileptiform discharges through the concomitant overactivation of glutamate receptors. Under these conditions, a facilitated GABA-mediated transmission may paradoxically boost neuronal hyperexcitation. Riluzole, a drug used to treat amyotrophic lateral sclerosis, seems to be toxic when combined with neuronal hyperexcitation.

Reduction in hospitalization costs, morbidity, disability, and mortality in patients with aids treated with protease inhibitors

BACKGROUND

The objective of this study was to analyze hospitalization costs, morbidity, disability, and mortality in patients with acquired immunodeficiency syndrome (AIDS) treated with protease inhibitors (PI).

METHODS

This is a self-controlled, ambispective study of a total of 581 patients with human immunodeficiency virus (HIV)/AIDS seen at the Hospital de Infectología, Centro Médico La Raza, IMSS, in Mexico City during 1997. A total of 210 (36.14%) patients initiated protease inhibitor (PI) treatment at the onset of the study. Thirty-eight patients satisfied the inclusion criteria for this study and were analyzed retrospectively during the year prior to PI treatment, and then prospectively throughout the year on PI treatment. As concerns main outcome measures, financial costs, number of hospitalizations, number of infections, and productivity and laboratory parameters (CD4(+) counts and viral load) were analyzed during the year prior to PI treatment and then prospectively during the year on PI prescription. Our hypothesis was that the hospital costs, morbidity, disability, and mortality of patients with AIDS decreased while on PI treatment.

RESULTS

During the year prior to PI prescription, the 38 patients enrolled in the study were admitted on a total of 59 occasions (1.55 hospitalizations/patient), whereas during the year on PI therapy, all 38 patients had only seven admissions (0.18 hospitalizations/patient). Hospitalization costs decreased 35% when annual PI costs for the 38 patients studied were taken into account. The number of microorganisms detected during hospitalization decreased from 24 prior to PI to five on PI. The number of disability days involved in patients on PI decreased significantly (p <0.0002). None of the 38 patients studied died during the year of follow-up under PI treatment. Mortality decreased significantly, from 116/481 (23.2%) in 1996, to 77/581 (13.2%) in 1997, to 40/740 (6.4%) in 1998. There were no deaths among the 38 patients studied during the 1-year follow-up period; when the observation period was extended 1 additional year, only one patient died (2.63%). Only six (3.48%) of the 172 PI-treated patients with AIDS not included in the study died during the same period. CD4(+) cell counts increased from 190.56 +/- 169.5 cells/mm(3) to 235.00 +/- 112.65 cells/mm(3) (p <0.05) after 12 months of PI treatment. Viral loads decreased from 5 logs to 2.4 logs at 12 months of PI treatment (p <0.001).

CONCLUSIONS

Introduction of PI to antiretroviral treatment in patients with AIDS was associated with a lower rate of hospital admissions, lower costs, and a lesser number of infections/year, disabilities, and mortalities. Increase of CD4(+) cell counts and decrease in viral loads in the 38 patients were associated with decreased morbility and mortality.

Absence of enteroviral RNA in hearts explanted from patients with dilated cardiomyopathy

BACKGROUND

The role of enterovirus infection in the pathogenesis of dilated cardiomyopathy (DCM) remains unclear. The objective of this study was to determine the prevalence of enterovirus in hearts explanted from patients with DCM and to compare it with enterovirus prevalence in hearts explanted from patients with other etiologies and in healthy donor hearts.

METHODS

A total of 138 cardiac samples were analyzed, 70 from heart donors and 68 from transplant recipients (22 with DCM). A highly sensitive enterovirus-specific nested RT-PCR was used to test for enterovirus.

RESULTS

All tests were negative except for one positive result that was attributed to carryover because sequencing of the amplification product showed it to be identical to the positive control.

CONCLUSIONS

In this study the sample of explanted hearts nested RT-PCR showed no evidence of the presence of enteroviral RNA. This suggests that if enterovirus had a role in the genesis of DCM, it does not require or lead to the persistence of the virus in myocardial tissue.

Beekeeper' arthropathy

OBJECTIVE

To describe the clinical, analytical, and radiological features of an observed arthropathy affecting beekeepers.

METHODS

Prospective study of 34 patients (32 male, 2 female), mean age 42 years (range 16 to 66 years), evaluated for the presence of acute or chronic arthritis related to beekeeping. All patients were working and living in the same village, Fuenlabrada de los Montes (1300 habitants), where there is a census of 180 beekeepers. An epidemiologic inquiry reported that > 50% of them reported episodes of arthritis on the hands during the month of August, at the time of honey collection.

RESULTS

Acute arthritis was observed in 10 patients. Pain, tenderness, joint swelling, and warmth were present in most cases. Chronic arthropathy was noted in 32 patients. Tenderness was present in 16 cases, synovial thickening in 12, limited joint mobility in 8, bony swelling in 15, and joint deformities in 13 patients. Radiological study showed periarticular soft tissue swelling, bone sclerosis, periostitis, bony erosions, subchondral cysts, geodes, osteophytes, and joint narrowing.

CONCLUSION

Beekeepers have joint disease apparently related to bee stings. Etiopathogenesis is unknown. Mechanical trauma, venom compounds, infection, and foreign body synovitis are factors that are thought to influence the pathogenesis of this syndrome. We designate the condition "beekeepers' arthropathy," and consider it an occupational disorder.

Neurotoxic and synaptic effects of okadaic acid, an inhibitor of protein phosphatases

Protein phosphorylation and dephosphorylation reactions, catalyzed by kinases and phosphatases, are involved in the regulation of a wide variety of physiological processes. In the nervous system, such reactions seem to modulate the function of several proteins crucial in synaptic transmission, including voltage-gated and ligand-gated channels, neurotransmitter release, and neurotransmitter transporters. On the other hand, hyperphosphorylation of certain cytoskeletal proteins or receptors may lead to neuronal death. In the present work we review the neurotoxic effect of okadaic acid (OKA), a potent and specific inhibitor of the serine/threonine protein phosphatases 1 and 2A, as well as its action on synaptic function. We analyze recent findings demonstrating that the microinjection of OKA in rat hippocampus induces neuronal stress, hyperexcitation and neurodegeneration, and discuss their possible relationships to alterations of protein phosphorylation-dephosphorylation observed in Alzheimer's disease brain. These results suggest that protein hyperphosphorylation due to inhibition of phosphatases in vivo induces neuronal stress and subsequent neurodegeneration.

Relationships among seizures, extracellular amino acid changes, and neurodegeneration induced by 4-aminopyridine in rat hippocampus: a microdialysis and electroencephalographic study

4-Aminopyridine is a powerful convulsant that induces the release of neurotransmitters, including glutamate. We report the effect of intrahippocampal administration of 4-aminopyridine at six different concentrations through microdialysis probes on EEG activity and on concentrations of extracellular amino acids and correlate this effect with histological changes in the hippocampus. 4-Aminopyridine induced in a concentration-dependent manner intense and frequent epileptic discharges in both the hippocampus and the cerebral cortex. The three highest concentrations used induced also a dose-dependent enhancement of extracellular glutamate, aspartate, and GABA levels and profound hippocampal damage. Neurodegenerative changes occurred in CA1, CA3, and CA4 subfields, whereas CA2 was spared. In contrast, microdialysis administration of a depolarizing K+ concentration and of tetraethylammonium resulted in increased amino acid levels but no epileptic activity and no or moderate neuronal damage. These results suggest that seizure activity induced by 4-aminopyridine is due to a combined action of excitatory amino acid release and direct stimulation of neuronal firing, whereas neuronal death is related to the increased glutamate release but is independent of seizure activity. In addition, it is concluded that the glutamate release-inducing effect of 4-aminopyridine results in excitotoxicity because it occurs at the level of nerve endings, thus permitting the interaction of glutamate with its postsynaptic receptors, which is probably not the case after K+ depolarization.