Production of recombinant proteins in E. coli by the heat inducible expression system based on the phage lambda pL and/or pR promoters

The temperature inducible expression system, based on the pL and/or pR phage lambda promoters regulated by the thermolabile cI857 repressor has been widely use to produce recombinant proteins in prokaryotic cells. In this expression system, induction of heterologous protein is achieved by increasing the culture temperature, generally above 37 degrees C. Concomitant to the overexpression of heterologous protein, the increase in temperature also causes a variety of complex stress responses. Many studies have reported the use of such temperature inducible expression system, however only few discuss the simultaneous stress effects caused by recombinant protein production and the up-shift in temperature. Understanding the integral effect of such responses should be useful to develop improved strategies for high yield protein production and recovery. Here, we describe the current status of the heat inducible expression system based on the pL and/or pR lambda phage promoters, focusing on recent developments on expression vehicles, the stress responses at the molecular and physiological level that occur after heat induction, and bioprocessing factors that affect protein overexpression, including culture operation variables and induction strategies.

Validation of three viable-cell counting methods: Manual, semi-automated, and automated

A viable cell count is essential to evaluate the kinetics of cell growth. Since the hemocytometer was first used for counting blood cells, several variants of the methodology have been developed towards reducing the time of analysis and improving accuracy through automation of both sample preparation and counting. The successful implementation of automated techniques relies in the adjustment of cell staining, image display parameters and cell morphology to obtain equivalent precision, accuracy and linearity with respect to the hemocytometer. In this study we conducted the validation of three trypan blue exclusion-based methods: manual, semi-automated, and fully automated; which were used for the estimation of density and viability of cells employed for the biosynthesis and bioassays of recombinant proteins. Our results showed that the evaluated attributes remained within the same range for the automated methods with respect to the manual, providing an efficient alternative for analyzing a huge number of samples.

The births of five Spanish babies from cryopreserved donated oocytes

BACKGROUND

The technique of freezing oocytes is still not widely used. Reasons cited for this include the technique's low efficacy and the risk of aneuploidy. However, the introduction of technical changes (the type and concentration of cryoprotective substances; slow freezing and rapid thawing; and fertilization by ICSI) has led to improved results. We present four pregnancies obtained using mature oocytes (in metaphase II) that had been frozen and thawed. The oocytes were donated by young women who were not patients.

METHODS

The frozen oocytes (n = 88) came from seven donors aged 18-25 years. The metaphase II oocytes, morphologically normal in appearance, were denuded of their cumulus-corona complex. The cryoprotective freezing solution contained 1,2-propanediol (1.5 mol/l) and sucrose (0.3 mol/l). Freezing was slow and thawing rapid. The oocytes were fertilized by ICSI.

RESULTS

Seventy-nine of the 88 thawed oocytes survived (89.8%); 58 were fertilized (73.4% of all those microinjected); and 26 were transferred (44.8% of all those fertilized). Four pregnancies were produced after seven transfers (57.1%). Five children were born from four pregnancies.

CONCLUSIONS

With the freezing/thawing technique used, oocyte survival was high ( approximately 90%). The pregnancy rate with frozen oocytes was similar to that obtained using fresh oocytes from donors ( approximately 50%).

Monitoring the impact of desert dust outbreaks for air quality for health studies

We review the major features of desert dust outbreaks that are relevant to the assessment of dust impacts upon human health. Our ultimate goal is to provide scientific guidance for the acquisition of relevant population exposure information for epidemiological studies tackling the short and long term health effects of desert dust. We first describe the source regions and the typical levels of dust particles in regions close and far away from the source areas, along with their size, composition, and bio-aerosol load. We then describe the processes by which dust may become mixed with anthropogenic particulate matter (PM) and/or alter its load in receptor areas. Short term health effects are found during desert dust episodes in different regions of the world, but in a number of cases the results differ when it comes to associate the effects to the bulk PM, the desert dust-PM, or non-desert dust-PM. These differences are likely due to the different monitoring strategies applied in the epidemiological studies, and to the differences on atmospheric and emission (natural and anthropogenic) patterns of desert dust around the world. We finally propose methods to allow the discrimination of health effects by PM fraction during dust outbreaks, and a strategy to implement desert dust alert and monitoring systems for health studies and air quality management.

2001-2012 trends on air quality in Spain

This study aims at interpreting the 2001-2012 trends of major air pollutants in Spain, with a major focus on evaluating their relationship with those of the national emission inventories (NEI) and policy actions. Marked downward concentration trends were evidenced for PM10, PM2.5 and CO. Concentrations of NO2 and NOx also declined but in a lesser proportion at rural and traffic sites. At rural sites O3 has been kept constant, whereas it clearly increased at urban and industrial sites. Comparison of the air quality trends and major inflection points with those from NEIs, the National Energy Consumption and the calendar of the implementation of major policy actions allowed us to clearly identify major benefits of European directives on power generation and industrial sources (such as the Large Combustion Plants and the Integrated Pollution Prevention and Control Directives). This, together with a sharp 2007-2008 decrease of coal consumption has probably caused the marked parallel decline of SO2, NOx and for PM2.5 concentrations. Also the effect of the EURO 4 and 5 vehicle emission standards on decreasing emissions of PM and CO from vehicles is noticeable. The smooth decline in NO2-NOx levels is mostly attributed to the low efficiency of EURO 4 and 5 standards in reducing real life urban driving NO2 emissions. The low NOx decrease together with the complexity of the reactions of O3 formation is responsible for the constant O3 concentrations, or even the urban increase. The financial crisis has also contributed to the decrease of the ambient concentration of pollutants; however this caused a major reduction of the primary energy consumption from 2008 to 2009, and not from 2007 to 2008 when ambient air PM and SO2 sharply decreased. The meteorological influence was characterized by a 2008-2012 period favorable to the dispersion of pollutants when compared to the 2001-2007.

A between-subjects comparison of respiratory sinus arrhythmia and baroreceptor cardiac reflex sensitivity as non-invasive measures of tonic parasympathetic cardiac control

Respiratory sinus arrhythmia (RSA) has been used as an index of parasympathetic cardiac control. However, recent psychophysiological research casts serious doubts upon the usefulness of RSA as an index of vagal influences upon the heart in psychophysiological as well as in clinical studies. It suggests the need to look for another measure. In this exploratory study we investigated whether the baroreflex sensitivity (BRS) could serve as an alternative tool to investigate between-subject tonic parasympathetic influences on the heart. In nine healthy subjects we examined the effects of intravenous atropine (0.03 mg/kg i.v.), intravenous metoprolol (10-15 mg i.v.), and of saline as a placebo condition upon RSA, BRS, and related cardiovascular and respiratory variables, both under resting and under mental task conditions. After parasympathetic blockade, RSA and BRS display values near zero, showing their vagal origin. After beta-adrenergic blockade, when heart period is predominantly under vagal control, RSA fails to predict heart period variability. Using BRS, however, it is possible to predict more than 97% of heart period variance during beta-blockade. Finally, both the vagal and beta-adrenergic blockade show that BRS is a better predictor of parasympathetic cardiac control during blood pressure increases than during blood pressure decreases.

Local allergic rhinitis: Implications for management

A significant proportion of rhinitis patients without systemic IgE-sensitisation tested by skin prick test and serum allergen-specific IgE (sIgE) display nasal reactivity upon nasal allergen provocation test (NAPT). This disease phenotype has been termed local allergic rhinitis (LAR). LAR is an underdiagnosed entity affecting children and adults from different parts of the world, with moderate-to-severe symptoms, impairment of quality of life and rapid progression to symptom worsening. LAR is a stable phenotype and not merely an initial state of AR. Allergic rhinitis and LAR share many clinical features including a positive NAPT response, markers of type 2 nasal inflammation including sIgE in nasal secretions and a significant rate of asthma development. LAR should be considered as a differential diagnosis in those subjects of any age with symptoms suggestive of AR but no evidence of systemic atopy. Although LAR pathophysiology is partially unknown, in some patients sIgE can be demonstrated directly in the nasal secretions and/or indirectly via positive responses in basophil activation test (BAT). LAR can coexist with other rhinitis phenotypes, especially AR. The diagnosis currently relies on the positivity of NAPT to a single or multiple allergens. NAPT has high sensitivity, specificity and reproducibility, and it is considered the gold standard. BAT and the measurement of nasal sIgE can also contribute to LAR diagnosis. LAR patients benefit from the same therapeutic strategies than AR individuals, including the avoidance of allergen exposure and the pharmacotherapy. Moreover, several recent studies support the effectiveness and safety of allergen immunotherapy for LAR, which opens a window of treatment opportunity in these patients.

Duodenal switch: an effective therapy for morbid obesity--intermediate results

BACKGROUND

The duodenal switch (DS) is a variant of the biliopancreatic diversion (BPD), with a vertical subtotal gastrectomy and pylorus preservation.

METHODS

DS was used to treat morbid obesity in 125 patients, with mean BMI 50, with 65% of the patients super obese (SO). Patients have been followed for an intermediate period.

RESULTS

The percentage of excess weight loss (%EWL) was > 70% at 1 year, and reached 81.4% at 5 years when 97% of the patients had a %EWL > 50%. Comorbidities were cured or improved in all patients.

CONCLUSION

DS was very effective for the treatment of the morbid obesity in the SO patients.

Andersen syndrome autosomal dominant in three generations

Andersen syndrome is a rare entity and comprises potassium sensitive periodic paralysis, ventricular arrhythmia, and an unusual facial appearance; syncope and sudden death have also been reported. The recognition of the characteristic face permits an early diagnosis in order to detect the severe systemic manifestations that are associated with this syndrome. The genetic defect is not linked to any other form of potassium sensitive periodic paralysis nor is it related to that of the long QT syndrome; nevertheless, a prolonged QT interval can be detected in a significant proportion of the cases. Sixteen cases of this syndrome have been described. We report on a three-generation family with 10 affected members. To our knowledge, this is the largest number of cases reported in one family. We noted some additional minor anomalies such as broad forehead and malar hypoplasia. Our patients had variable expression in the classical triad and of the severity of the systemic manifestations. Five of 8 affected studied members did not have a long QTc, which has been suggested as a constant finding in this syndrome.

Size fractionate particulate matter, vehicle traffic, and case-specific daily mortality in Barcelona, Spain

Recent epidemiological research suggests that short-term effects of particle matter (PM) in urban areas may preferentially be driven by fine fractions. Questions remain concerning the adversehealth effects of coarse particles generated by noncombustion, traffic-related processes and the mechanism of action of PM. Using a time-stratified case-crossover design, we investigated the association between three independent size fractions, coarse (PM10-2.5), intermodal (PM2.5-1), and very fine PMs (PM1), and three health outcomes, respiratory, cardiovascular, and cerebrovascular mortality in Barcelona, Spain, during the period of March 2003-December 2005. Using existing data, we examined the chemical composition of each fraction to explore the effects of PM from different sources and the mechanisms of action. We found that increased levels of PM, and PM10-2.5 were associated with increased levels of cardiovascular and cerebrovascular mortality at lag 1 and lag 2. At lag 1, the odds ratio (OR) for a 1 microg/m3 increase in PM1 was 1.028 [95% confidence interval (CI), 1.000-1.058] for cardiovascular mortality and 1.063 (95% CI, 1.004-1.124) for cerebrovascular mortality. At lag 1, the odds ratio per a 10 microg/ m3 increase of PM10-2.5 was 1.059 (95% CI, 1.026-1.094) for cardiovascular mortality and 1.098 (95% CI, 1.030-1.171) for cerebrovascular mortality. Association with respiratory mortality was only detected for PM2.5-1 at lag 2 (OR, 1.206 per a 10 microg/ m3 increase; 95% CI, 1.028-1.416). Chemical composition data showed that PM in Barcelona was generated in a large proportion by vehicle traffic. Vehicle traffic PM, generated by combustion and noncombustion processes, should be considered in air pollution mitigation strategies in urban areas.

Immunohistochemically proven cytomegalovirus end-organ disease in solid organ transplant patients: clinical features and usefulness of conventional diagnostic tests

We studied the main clinical features, outcome, and laboratory parameters in a group of solid organ transplant (SOT) patients with immunohistochemically proven cytomegalovirus (CMV) disease. Confirmed CMV cases were obtained through databases. Demographics, clinical data, transplantation type, immunosuppressive regimens, donor and recipient CMV serostatus, therapy, outcome and laboratory results, pp65 antigenemia, and qualitative polymerase chain reaction (PCR) for CMV were analyzed. From 1995 to 2004, 31 cases with complete medical records were identified. Disease appeared between 24 and 2538 days after transplantation but most cases presented in the first 100 days. Gastrointestinal CMV disease was the most frequent form (71%), while thrombocytopenia was present in 50% of cases, and leukopenia was less common (35.5%). CMV pp65 antigenemia was positive in 58% of patients, but its sensitivity increased to 71% if performed during the first 6 months. A qualitative CMV PCR technique gave similar results during this period (71.4%). Most patients were treated with intravenous ganciclovir (n=25; 80.6%). In 4 cases (19.4%), use of foscarnet alone or a sequential regimen with ganciclovir-foscarnet was deemed necessary. Surgical procedures were necessary in 5 patients (16%). The death rate reached 13%. CMV end-organ disease can be a life-threatening infection in SOT patients. Gastrointestinal disease was the most frequent end-organ disease. CMV antigen detection is best suited for the early period after transplantation.

Recognizing a mother's voice in the persistent vegetative state

We studied an 8-year-old boy after a near-drowning left him in a vegetative state (VS) for 4 years before the study. Findings fulfilled all clinical criteria for the diagnosis of VS. The purpose of this study was to investigate whether there was significant differential activation of the brain in response to hearing his mother's voice compared with the voices of unknown women. The data were assessed using quantitative electric tomography (QEEGt), a technique that combines anatomical information of the brain by MRI with EEG patterns to estimate the sources of the EEG within the brain. We found significant differences for EEG frequencies from 14-58 Hz, with a peak at 33.2 Hz (gamma band). The 3D reconstruction showed that these statistical differences were localized in the lateral and posterior regions of the left hemisphere. No significant differences were found between unknown women vs. basal conditions. These results demonstrate recognition of the mother's voice and indicate high-level residual linguistic processing in a patient meeting clinical criteria for VS. These findings launch new ethical and practical implications for the management of VS patients.

African dust and air quality over Spain: Is it only dust that matters?

The 2001-2016 contribution of African dust outbreaks to ambient regional background PM10 and PM2.5 levels over Spain, as well as changes induced in the PMx composition over NE Spain in 2009-2016, were investigated. A clear decrease in PMx dust contributions from the Canary Islands to N Iberia was found. A parallel increase in the PM2.5/PM10 ratio (30% in the Canary Islands to 57% in NW Iberia) was evidenced, probably due to size segregation and the larger relative contribution of the local PMx with increasing distance from Africa. PM1-10 and PM2.5-10 measured in Barcelona during African dust outbreaks (ADOs) were 43-46% higher compared to non-ADO days. The continental background contribution prevailed in terms of both PM1-10 and PM2.5-10 during ADO days (62 and 69%, respectively, and 31 and 27% for non-ADO days). The relative contributions of Al₂O₃/Fe₂O₃/CaO to PMx fraction showed that Al₂O₃ is a suitable tracer for African dust in our context; while CaO at the urban site is clearly affected by local resuspension, construction and road dust, and Fe₂O₃ by dust from vehicle brake discs. The results also provide evidence that PM increases during ADOs are caused not only by the mineral dust load, but by an increased accumulation of locally emitted or co-transported anthropogenic pollutants as compared with non-ADO days. Possible causes for this accumulation are discussed. We recommend that further epidemiological studies should explore independently the potential effects of mineral dust and the anthropogenic PM during ADOs, because, at least over SW Europe, not only mineral dust affects the air quality during African dust episodes.

Activity of aphids associated with lettuce and broccoli in Spain and their efficiency as vectors of Lettuce mosaic virus

This research sought to identify the aphid virus vector species associated with lettuce and broccoli crops in Spain, and to determine their population dynamics and ability to transmit Lettuce mosaic virus (LMV). Green tile traps and Moericke yellow water-pan traps were used to monitor aphid flights during the spring and autumn growing seasons of 2001. Aphid species feeding on lettuce were counted weekly. The transmission efficiencies of LMV were determined for the aphid species caught most frequently. The Moericke traps generally caught more aphid species than the tile trap, but the latter was the most suitable to estimate flight activity of species involved in virus spread. Spring aphid catches indicated that the main aphid species landing on lettuce in the regions of Madrid and Murcia was Hyperomyzus lactucae, but Brachycaudus helichrysi was also abundant in both regions. In broccoli in the Navarra region, the most abundant species in spring were Aphis fabae, B. helichrysi and H. lactucae. In autumn-sown crops, the main species landing on lettuce in the Madrid region were Hyadaphis coriandri and Aphis spiraecola. In Murcia, A. spiraecola and Myzus persicae were the most abundant, while in Navarra, Therioaphis trifolii, and various Aphis spp. were the most numerous landing on broccoli. The main aphid species colonising lettuce was Nasonovia ribisnigri, but other less abundant colonising species were Aulacorthum solani and Macrosiphum euphorbiae. The most efficient vectors of LMV were M. persicae, Aphis gossypii and M. euphorbiae, while A. fabae and H. lactucae transmitted with low efficiency, and Rhopalosiphum padi and N. ribisnigri did not transmit. Occurrence of LMV epidemics in central Spain in relation to aphid flights and the role of weeds as virus reservoirs is discussed.

Analysis of recombinant monoclonal antibodies by capillary zone electrophoresis

Analytical platforms that characterize charge heterogeneity in therapeutic proteins, such as mAbs, are important tools that can be used to define quality attributes. CZE separates protein moieties close to their native state and is a valuable physicochemical analytical method that can be used in parallel with other orthogonal methods for characterization and comparability. In this study, custom conditions for the analysis of charge heterogeneity of two mAbs were developed with regard to critical parameters in the BGE, running conditions, and sample treatment. The method application was tested for up to four mAbs and one mAb fragment. The electropherograms showed specific profiles and contrasting levels of basic and acidic isoforms with respect to the main isoform. Issues that surround this method, such as peak tailing and capillary lifetime, are summarized. Using this method, the identities of rituximab and trastuzumab were confirmed, based on the correspondence between the biosimilars and reference products, noninterference of the sample matrix, and the ability to separate spiked samples of related mAbs. The RSD of the isoform content and migration time for the method repeatability were less than 2 and 1%, respectively.

Native valve endocarditis due to Candida glabrata treated without valvular replacement: a potential role for caspofungin in the induction and maintenance treatment

Conventional antifungal therapy for fungal endocarditis has been associated with a poor cure rate. Therefore, combined medical and surgical therapy has been recommended. However, new potent antifungal agents, such as echinocandins, could increase the medical options and, in some cases, avoid the need for surgery. We report a case of Candida endocarditis treated successfully without valve replacement with intravenous liposomal amphotericin B (total dose, 4 g) and intravenous caspofungin (a 100-mg loading dose followed by 50 mg per day for 8 weeks) as induction therapy and intravenous caspofungin (100 mg 3 times per week for 12 weeks) as maintenance therapy.

Interpretation of the variability of levels of regional background aerosols in the Western Mediterranean

Results on interpretation of the variability of regional background PM levels in the Western Mediterranean basin (WMB) are presented. Mean PM levels recorded at Montseny, MSY (North-Eastern Spain) in the 2002--2007 period reached 17, 13 and 11 microg/m3 of PM10, PM2.5 and PM1, respectively. The daily evolution of PM levels is regulated by the breeze circulation (mountain and sea breezes). PM levels are lower at the rural sites at night owing to the nocturnal drainage flows and to the lowering of the mixing layer height below the MSY high. These nocturnal low levels allowed us to estimate the continental background PM levels. At midday, the atmospheric pollutants accumulated in the pre-coastal depression are transported upwards by the breeze, increasing PM levels. Maximum PM10 levels were recorded in summer, and February--March and November, and minimum values in the rest of the year coinciding with the highest frequency of Atlantic advection. PM peak episodes attributed to Saharan dust outbreaks were recorded in summer and February-March. In addition, anticyclonic situations (February--March and November) may impact in elevated rural areas by increasing hourly levels of PM1 up to 75 microg/m3. This scenario induces the stagnation of pollutants in the pre-coastal depression. Solar radiation activates mountain winds, transporting polluted air masses from the valleys to elevated areas resulting in an increase of fine PM levels in areas outside the boundary layer. A significant decrease in PM annual means (40% and 34% for the entire monitoring period, 7 microgPM10/m3 and 5 microgPM2.5/m3) was recorded at MSY between 2002 and 2007. There appears to be no single cause behind these trends. This could partially be ascribed to the varying frequency and intensity of Saharan dust episodes, but also to large-scale meteorological processes or cycles, and/or to local or meso-scale processes such as nearby anthropogenic emission sources.

Effect of probiotic supplementation on immunoglobulins, isoagglutinins and antibody response in children of low socio-economic status

BACKGROUND

Antigen exposure is one of the major exogenous factors modulating human immunocompetence acquisition. Decline in family size and improvements in public health and hygiene in developed countries, may deprive the immune system of appropriate antigen input by diminishing infectious stimuli. Probiotics are a large group of microorganisms defined by their beneficial effects on human health and with stimulating effects on different functions of the immune system.

AIM OF THE STUDY

We conducted a double-blind, placebo-controlled trial to determine if probiotics maintain their immune-stimulating effects in a population of 162 children with a high index of natural exposure to microorganisms. Children were to ingest for at least 4 months one of two products, low-fat milk fermented by Streptococcus thermophilus (control product) or low-fat milk fermented by S. thermophilus and Lactobacillus casei, with Lactobacillus acidophilus, oligofructose and inulin added after the fermentation process (test product). According to their age, children were vaccinated with DTP-Hib vaccine or a 23-valent anti-pneumococcal vaccine.

RESULTS

Final analysis of results was done in 70 children in each group, showing that the rate of immunoglobulin and isoagglutinin acquisition was similar in both groups. There was no difference between groups in antibody levels neither before nor after vaccination. Days of fever and number of episodes of infection were not statistically different in either group.

CONCLUSIONS

Supplementation of standard fermented milk with additional probiotics was not of benefit. The high natural rate of early microbial exposure in infants and children from a population of low socio-economic status living in a "less hygienic environment" may account for the absence of an additional immune-stimulating effect by supplementary probiotics.

Influence of vesicle curvature on fluorescence relaxation kinetics of fluorophores

The effect of membrane curvature on the fluorescence decay of 2-p-toluidinyl-naphthalene-6-sulfonic acid (TNS), 2-(9-anthroyloxy) stearic acid (2-AS) and 12-(9-anthroyloxy)-stearic acid (12-AS) was investigated for egg lecithin vesicles of average diameter dm = 22 nm and 250 nm. The biexponential fluorescence decay of TNS at the red edge of the emission spectrum was analysed according to the model of Gonzalo and Montoro [1]. Over the entire temperature range (1-40 degrees C) the small TNS labelled vesicles showed significantly shorter solvent relaxation times tau(r) than their larger counterparts (e.g. 1.3 ns compared with 2.1 ns at 5 degrees C), indicating a higher mobility of the hydrated headgroups in the highly curved, small vesicles. The fluorescence decay of both AS derivatives is also biexponential. While the shorter decay times (1-3 ns) are practically identical for small and large vesicles, the longer decay times (5-14 ns) are identical only for 12-AS but not for 2-AS. This indicates that the microenvironment is similar in small and large vesicles deep in the membrane in spite of the differences in curvature.

Process signatures in glatiramer acetate synthesis: structural and functional relationships

Glatiramer Acetate (GA) is an immunomodulatory medicine approved for the treatment of multiple sclerosis, whose mechanisms of action are yet to be fully elucidated. GA is comprised of a complex mixture of polypeptides with different amino acid sequences and structures. The lack of sensible information about physicochemical characteristics of GA has contributed to its comprehensiveness complexity. Consequently, an unambiguous determination of distinctive attributes that define GA is of highest relevance towards dissecting its identity. Herein we conducted a study of characteristic GA heterogeneities throughout its manufacturing process (process signatures), revealing a strong impact of critical process parameters (CPPs) on the reactivity of amino acid precursors; reaction initiation and polymerization velocities; and peptide solubility, susceptibility to hydrolysis, and size-exclusion properties. Further, distinctive GA heterogeneities were correlated to defined immunological and toxicological profiles, revealing that GA possesses a unique repertoire of active constituents (epitopes) responsible of its immunological responses, whose modification lead to altered profiles. This novel approach established CPPs influence on intact GA peptide mixture, whose physicochemical identity cannot longer rely on reduced properties (based on complete or partial GA degradation), providing advanced knowledge on GA structural and functional relationships to ensure a consistent manufacturing of safe and effective products.

Use of distortion-product otoacoustic emissions for auditory evaluation in Menière's disease

Otoacoustic emissions are a relatively new tool for assessment of inner ear function. We studied 65 patients diagnosed as having Menière's disease. In order to obtain and characterize responses at different frequencies we used distortion-product otoacoustic emissions (DPOAE). In unilateral cases, the difference in response between ears on the diseased and healthy sides was evident at all frequencies. In the former the result was lower than expected for a group of normally hearing subjects, while in the latter it was better than expected according to pure tone averages. Reduction in amplitude and increment in threshold of the DPOAE in the diseased ear was a significant finding and could be correlated to the stage of the disease. In those subjects treated with Betahistine after 1 year's follow-up, DPOAE testing showed the recovery of response at low frequencies and a reduction of its threshold at all frequencies studied.

Primary meningococcal conjunctivitis

Neisseria meningitidis is an uncommon cause of acute bacterial conjunctivitis. One case of primary meningococcal conjunctivitis in a healthy 6-year-old boy is reported. The patient was initially treated with a topical instillation of polymyxin B, neomycin and gramicidin in ophthalmic solution, and this was followed by systemic rifampin once the diagnosis had been established. No ocular or systemic complications developed.

Surface anisotropy broadening of the energy barrier distribution in magnetic nanoparticles

The effect of surface anisotropy on the distribution of energy barriers in magnetic fine particles of nanometer size is discussed within the framework of the Tln(t/τ(0)) scaling approach. The comparison between the distributions of the anisotropy energy of the particle cores, calculated by multiplying the volume distribution by the core anisotropy, and of the total anisotropy energy, deduced by deriving the master curve of the magnetic relaxation with respect to the scaling variable Tln(t/τ(0)), enables the determination of the surface anisotropy as a function of the particle size. We show that the contribution of the particle surface to the total anisotropy energy can be well described by a size-independent value of the surface energy per unit area which permits the superimposition of the distributions corresponding to the particle core and effective anisotropy energies. The method is applied to a ferrofluid composed of non-interacting Fe(3-x)O(4) particles of 4.9 nm average size and x about 0.07. Even though the size distribution is quite narrow in this system, a relatively small value of the effective surface anisotropy constant K(s) = 2.9 × 10(-2) erg cm(-2) gives rise to a dramatic broadening of the total energy distribution. The reliability of the average value of the effective anisotropy constant, deduced from magnetic relaxation data, is verified by comparing it to that obtained from the analysis of the shift of the ac susceptibility peaks as a function of the frequency.