Proteasome-dependent degradation of histone H1 subtypes is mediated by its C-terminal domain

Histone H1 is involved in chromatin compaction and dynamics. In human cells, the H1 complement is formed by different amounts of somatic H1 subtypes, H1.0-H1.5 and H1X. The amount of each variant depends on the cell type, the cell cycle phase, and the time of development and can be altered in disease. However, the mechanisms regulating H1 protein levels have not been described. We have analyzed the contribution of the proteasome to the degradation of H1 subtypes in human cells using two different inhibitors: MG132 and bortezomib. H1 subtypes accumulate upon treatment with both drugs, indicating that the proteasome is involved in the regulation of H1 protein levels. Proteasome inhibition caused a global increase in cytoplasmatic H1, with slight changes in the composition of H1 bound to chromatin and chromatin accessibility and no alterations in the nucleosome repeat length. The analysis of the proteasome degradation pathway showed that H1 degradation is ubiquitin-independent. The whole protein and its C-terminal domain can be degraded directly by the 20S proteasome in vitro. Partial depletion of PA28γ revealed that this regulatory subunit contributes to H1 degradation within the cell. Our study shows that histone H1 protein levels are under tight regulation to prevent its accumulation in the nucleus. We revealed a new regulatory mechanism for histone H1 degradation, where the C-terminal disordered domain is responsible for its targeting and degradation by the 20S proteasome, a process enhanced by the regulatory subunit PA28γ.

Effects of ascorbic acid addition on the oxidative stress response of Oryza sativa L. plants to As(V) exposure

Accumulation of noxious elements in the edible part of crops and its impact on food safety is of increasing concern. Rice is one of the major staple food crops worldwide, including arsenic (As)-polluted areas, in which dietary As exposure is becoming a widespread health threat. Plant chemical priming has been shown to be an effective strategy to enhance tolerance to environmental stresses, including metal(loid) exposure. The priming effect of ascorbic acid (AsA) was assessed in rice seedlings exposed to As(V) in a hydroponics experiment. AsA treatment (co-addition to the growing media concomitantly (t₀) or 24 h in advance (t₂₄)) prevented an excessive accumulation of As in the roots (that decreased ∼ 60%) and stimulated the activities of photosynthetic and antioxidant attributes (∼1.2-fold) in the aerial part of the plants. The increase in proline levels in both shoots (∼2.1-fold) and roots (∼2.4-fold) was found to be the most sensitive stress parameter, and was able to reflect the AsA-induced reduction of As toxic effects (concentrations back to Control levels, both simultaneously added or added as a pretreatment) in the aerial part of the plants. However, the phytotoxic effects related to As exposure were not fully prevented by priming with AsA, and further research is needed to find alternative priming approaches.

Antivenom effect on lymphatic absorption and pharmacokinetics of coral snake venom using a large animal model

Context: Historically, administration and dosing of antivenom (AV) have been guided primarily by physician judgment because of incomplete understanding of the envenomation process. As demonstrated previously, lymphatic absorption plays a major role in the availability and pharmacokinetics (PK) of coral snake venom injected subcutaneously, which suggests that absorption from subcutaneous tissue is the limiting step for venom bioavailability, supporting the notion that the bite site is an ongoing venom depot. This feature may underlie the recurrence phenomena reported in viperid envenomation that appear to result from a mismatch between venom and AV PK. The role of lymphatic absorption in neutralization of venom by AV administered intravenously remains unclear. Methods: The effect of AV on systemic bioavailability and neutralization of Micrurus fulvius venom was assessed using a central lymph-cannulated sheep model. Venom was administered by subcutaneous injection in eight sheep, four with and four without thoracic duct cannulation and drainage. Two hours after venom injection, AV was administered intravenously. Venom and AV concentrations in serum and lymph were determined by ELISA assay from samples collected over a 6-h period and in tissues harvested post-mortem. Results: After AV injection, venom levels in serum fell immediately to undetectable with a subsequent increase in concentration attributable to non-toxic venom proteins. In lymph, AV became detectable 6 min after treatment; venom levels dropped concurrently but remained detectable 4 h later. Post-mortem samples from the venom injection site confirmed the presence of venom near the point of injection. Neither venom nor AV was detected at significant concentrations in major organs or contralateral skin. Conclusions: Intravenous AV immediately neutralizes venom in the bloodstream and can extravasate to neutralize venom absorbed by lymph but this neutralization seems to be slow and incomplete. Residual venom in the inoculation site demonstrates that this site functions as a depot where it is not neutralized by AV, which allows the venom to remain active with slow delivery to the bloodstream for ongoing systemic distribution.

Application of thermal lens microscopy (TLM) for measurement of Cr(VI) traces in wastewater

In this work, we demonstrate for the first time that Thermal Lens Microscopy technique (TLM) can be applied to monitor the dynamics of a photocatalytic process in-situ. The photocatalytic reduction of hexavalent chromium -Cr(VI)- in aqueous solution using CdS and irradiated with visible light is monitored by TLM. Since the values of Cr(VI) concentration obtained after the photocatalytic process were close to those imposed by the international regulations for drinking water, the use of TLM allowed its measurement with a better reliability than with UV spectroscopy, usually used in this kind of analysis.

Thermal diffusivity measurement in thin metallic filaments using the mirage method with multiple probe beams and a digital camera

Photothermal beam deflection is a well-established technique for measuring thermal diffusivity. In this technique, a pump laser beam generates temperature variations on the surface of the sample to be studied. These variations transfer heat to the surrounding medium, which may be air or any other fluid. The medium in turn experiences a change in the refractive index, which will be proportional to the temperature field on the sample surface when the distance to this surface is small. A probe laser beam will suffer a deflection due to the refractive index periodical changes, which is usually monitored by means of a quadrant photodetector or a similar device aided by lock-in amplification. A linear relationship that arises in this technique is that given by the phase lag of the thermal wave as a function of the distance to a punctual heat source when unidimensional heat diffusion can be guaranteed. This relationship is useful in the calculation of the sample's thermal diffusivity, which can be obtained straightforwardly by the so-called slope method, if the pump beam modulation frequency is well-known. The measurement procedure requires the experimenter to displace the probe beam at a given distance from the heat source, measure the phase lag at that offset, and repeat this for as many points as desired. This process can be quite lengthy in dependence of the number points. In this paper, we propose a detection scheme, which overcomes this limitation and simplifies the experimental setup using a digital camera that substitutes all detection hardware utilizing motion detection techniques and software digital signal lock-in post-processing. In this work, the method is demonstrated using thin metallic filaments as samples.

The thioredoxin/peroxiredoxin/sulfiredoxin system: current overview on its redox function in plants and regulation by reactive oxygen and nitrogen species

In plants, the presence of thioredoxin (Trx), peroxiredoxin (Prx), and sulfiredoxin (Srx) has been reported as a component of a redox system involved in the control of dithiol-disulfide exchanges of target proteins, which modulate redox signalling during development and stress adaptation. Plant thiols, and specifically redox state and regulation of thiol groups of cysteinyl residues in proteins and transcription factors, are emerging as key components in the plant response to almost all stress conditions. They function in both redox sensing and signal transduction pathways. Scarce information exists on the transcriptional regulation of genes encoding Trx/Prx and on the transcriptional and post-transcriptional control exercised by these proteins on their putative targets. As another point of control, post-translational regulation of the proteins, such as S-nitrosylation and S-oxidation, is of increasing interest for its effect on protein structure and function. Special attention is given to the involvement of the Trx/Prx/Srx system and its redox state in plant signalling under stress, more specifically under abiotic stress conditions, as an important cue that influences plant yield and growth. This review focuses on the regulation of Trx and Prx through cysteine S-oxidation and/or S-nitrosylation, which affects their functionality. Some examples of redox regulation of transcription factors and Trx- and Prx-related genes are also presented.

A method for thermal diffusivity measurement in fluids

A technique is proposed for thermal diffusivity measurement in fluids. It is based on the Angstrom method, but with excitation of thermal waves by electromagnetic energy absorption and pyroelectric detection. The good agreement between measured thermal diffusivity of air and some test liquids with literature values shows the validity of the method. It is free of some limitations of conventional photopyroelectric technique with length scanning because it is free of moving parts inside the sample and because it avoids problems associated with the non-parallelism between thermal wave generator surface and sensor. It does not require any data normalization procedure or special sample preparation.

[Proximal femoral intramedullary nail versus DHS plate for the treatment of intertrochanteric fractures. A prospective analysis]

OBJECTIVE

To show that patients with intertrochanteric fractures treated with a proximal femoral nail have a better postoperative course than those treated with a DHS plate (dynamic hip screw).

METHODS

Patients with a Boyd & Griffin type II intertrochanteric fracture were randomly divided into two groups: a group of patients treated with a PFN and another one treated with a DHS plate. All patients were assessed at 2, 4, 8 and 16 weeks using the Harris scale and the visual analog scale pre- and postoperatively, as well as the operative time, incision size, intraoperative bleeding, onset of partial and/or total weight bearing, healing time, time to attain prior physical activity level, and radiographic result.

RESULTS

32 patients met our criteria. The variables that had a significant reduction were: incision, operative time, postoperative pain according to the visual analog scale, onset of mobility, partial weight bearing and pain at 2 weeks.

CONCLUSIONS

The proximal femoral nail has better short-term outcomes than the DHS plate; however, in the medium term both implants have the same outcomes.

Lymphatic route of transport and pharmacokinetics of Micrurus fulvius (coral snake) venom in sheep

The contribution of the lymphatic system to the absorption and systemic bioavailability of Micrurus fulvius venom after subcutaneous (SC) administration was assessed using a central lymph-cannulated sheep model. Micrurus fulvius venom was administered either by intravenous bolus (IV) or subcutaneous injection (SC) in 12 sheep with and without thoracic duct cannulation and drainage. Venom concentration in serum and lymph was determined by a sandwich enzyme-linked immunosorbent assay (ELISA) in samples collected over a 6-hour period and in tissues harvested at the end of the experiment. Pharmacokinetic parameters were determined by a non-compartmental analysis. In the lymphatic cannulated group, over the 6 hours after the venom was administered, 69% of administered dose was accounted for in blood (45%) and lymph (25%). Negligible levels of venom were detected in organs and urine implying that the steady state observed after SC administration is maintained by a slow absorption process. Comparison of kinetics of the thoracic duct cannulated and non-cannulated groups showed that lymphatic absorption contributed in an important way to maintenance of this steady state. These results show that the limiting process in the pharmacokinetics of Micrurus fulvius venom following SC administration is absorption, and that the lymphatic system plays a key role in this process.

Thermal characterization of ZnO-DMSO (dimethyl sulfoxide) colloidal dispersions using the inverse photopyroelectric technique

Nanofluids, i.e., colloidal dispersions of nanoparticles in a base liquid (solvent), have received considerable attention in the last years due to their potential applications. One attractive feature of these systems is that their thermal conductivity can exceed the corresponding values of the base fluid and of the fluid with large particles of the same chemical composition. However, there is a lack of agreement between published results and the suggested mechanisms which explain the thermal conductivity enhancement. Here we show the possibilities of the inverse photopyroelectric method for the determination of the effective thermal effusivity of the system constituted by small ZnO nanoparticles dispersed in dimethyl sulfoxide, as a function of the nanoparticles volumetric fraction. Using a phenomenological model we estimated the thermal conductivity of these colloidal samples without observing any significant enhancement of this parameter above effective medium predictions.

High doses of lercanidipine are better tolerated than other dihydropyridines in hypertensive patients with metabolic syndrome: results from the TOLERANCE study

AIMS/INTRODUCTION

The TOlerabilidad de LERcanidipino 20 mg frente a Amlodipino y Nifedipino en CondicionEs normales de uso study was aimed to compare the tolerability of high doses of lercanidipine with amlodipine and nifedipine gastro-intestinal therapeutic system (GITS) in the treatment of hypertension in daily clinical practice.

PATIENTS/METHODS

Essential hypertensives >or= 18 years, treated during at least 1 month with lercanidipine 20 mg, amlodipine 10 mg or nifedipine GITS 60 mg, after a previous treatment course of at least 1 month with half the dose of the corresponding drugs were included. We present the data of the subgroup of patients with metabolic syndrome (MetS).

RESULTS

Three hundred and thirty-seven of the 650 study population fulfilled criteria of MetS, 233 (69.1%) on lercanidipine and 104 (30.9%) on amlodipine/nifedipine GITS. Overall, a significantly lower proportion of lercanidipine-treated patients showed adverse reactions (ARs) when compared with patients receiving other-dihydropyridines (DHPs) (60.1% vs. 73.1%, p = 0.003). Similarly, the most common vasodilation-related ARs (oedema, swelling, flushing and headache) were significantly less frequent in lercanidipine group (all p < 0.01).

CONCLUSION

In conclusion, lercanidipine appears to exhibit a better tolerability profile and less vasodilation-related ARs compared with other DHPs in hypertensive patients with MetS.

[Diabetes mellitus in hypertensive population attended in Primary Care in Spain. Blood pressure and lipid control rates]

OBJECTIVES AND METHODS

The aim of this study was to determine the blood pressure and LDL-cholesterol (LDL-c) control rates of hypertensive patients with diabetes mellitus attended in primary care setting in Spain, and to compare the data with those of the hypertensive population without diabetes. For this purpose, we analyzed the subset of diabetic patients of those included in the PRESCOT study (a cross-sectional survey of hypertensive subjects > 18 years attended in primary care). 12,954 patients (49.9% females; 62.1 +/- 10.7 years) were included in the PRESCOT study. Good controls were considered blood pressure < 130/80 mmHg (according to European Society of Hypertension-European Society of Cardiology [ESH-ESC] guidelines) and LDL-c < 100 mg/dl (National Cholesterol Education Program-Adult Treatment Panel III [NCEP-ATP III]).

RESULTS

Overall, 3868 (29.9%) of PRESCOT patients were diabetics (mean age 64.2 +/- 9.8 years; 47.5% males). Almost all the diabetic patients (98.5%) were taking some drug besides the antidiabetic treatment and 84.9% were taking at least 2 drugs. Although diabetic patients were treated with more antihypertensive medication than those without diabetes (48.75% vs 40.85% were on > 2 drugs, p < 0.001), blood pressure control was much lower in diabetics (6.3% vs 32.7%, p < 0.0001). In the same way, LDL-c control was also lower in these patients (12.0% vs 31.9%, p < 0.0001). Only 1.0% of diabetic hypertensives were well controlled for both risk factors (vs 11.9% of non-diabetics, p < 0.0001). Predictors of bad blood pressure control were sedentarism and presence of associated clinical conditions, and for lipid control the younger age, female gender, overweight, alcoholism and non-use of lipid-lowering agents.

CONCLUSIONS

The presence of diabetes in hypertensive population attended in Spanish primary health care is frequent. One out of every three hypertensives who attend the outpatient clinic daily is diabetic. Even though more drugs are prescribed in these patients, blood pressure and LDL-c control rates are significantly lower than in patients without diabetes. In the daily practice of primary care setting, almost no diabetic hypertensive subject is well controlled for blood pressure and LDL-c.

Photo-induced charge transfer in Prussian blue analogues as detected by photoacoustic spectroscopy

The photo-induced charge transfer in four series of Prussian blue (PB) analogues was studied from photoacoustic spectra. In cobalticyanides the observed signals were assigned to a metal-to-ligand charge transfer, which appears as a shoulder below 450 nm, and to d-d transitions for Co(II), Ni(II) and Cu(II) complex salts. No evidence of metal-to-metal charge transfer was observed for this series, which is probably due to the high stability of low spin cobalt(III) in the hexacyanide complex. Photoacoustic spectra for ferricyanides are broad bands, which result particularly intense up to 750 nm. Such features were attributed to the overlapping of contributions from metal-to-ligand (<600 nm) and metal-to-metal charge transfer transitions, with probably also a minor contribution from d-d transitions in the outer metal. The spectra for the ferrocyanides series are dominated by the metal-to-ligand charge transfer band below 550 nm, approximately 100 nm above this transition in cobalticyanides. Within the studied solids, the most intense and broad metal-to-metal charge transfer bands were found for a series of low spin Co(III) high spin Co(II) hexacyanoferrates(II,III) and with similar features also for ferric ferrocyanide (Prussian blue), assigned to Fe(II)-->Co(III) and Fe(II)-->Fe(III) photo-induced transition, respectively. The first of these transitions requires of more energetic photons to be observed, its maximum falls at 580 nm while for Prussian blue it is found at 670 nm. Prussian blue analogues are usually obtained as nanometric size particles and many of them have a microporous structure. The role of surface atoms on the observed charge transfer bands in the studied series of compounds is also discussed.

[Blood pressure and lipid control and coronary risk in the hypertensive population attended in Primary Care setting in Spain. The PRESCOT study]

OBJECTIVES AND METHODS

The aim of this cross-sectional and multicenter study was to determine the coronary risk of hypertensive patients attended in Spanish Primary Care and to evaluate whether blood pressure and LDL-cholesterol (LDL-c) control rates could change according to the ATP-III risk groups. Good blood pressure control was considered <140/90 mmHg (<130/80 mmHg for diabetics) and LDL-c according to the established by ATP-III for every risk group.

RESULTS

A total of 12,954 patients were included in the study (49.9 % women, mean age 62.1+/-10.7 years). Of these, 12.6% belonged to the group of low risk, 45% to the medium risk group and 42.4% to the high risk group. The control rates were different according to the risk group (p <0.0001). Blood pressure control: 37.5 % in low risk, 30.2 % in medium and 15.4 % in high risk group. LDL-c control: 65.6 % in low risk group, 28 % in medium risk group and 12.3 % in high risk group. Only 25.8 % of the patients of low risk were controlled for both blood pressure and LDL-c, 9.6 % of medium risk group and 2.7 % of high risk group.

CONCLUSIONS

The majority of hypertensive patients daily attended in Primary Care setting in Spain belongs to the medium or high coronary risk groups. Blood pressure and LDL-c controls rates in hypertensive population are low, and very few patients have both risk factors controlled. The control rates decline when the risk increases. In fact, less than 3% of high-risk patients have both parameters well controlled, what may result in significant clinical implications.

Cardiovascular risk profile and risk stratification of the hypertensive population attended by general practitioners and specialists in Spain. The CONTROLRISK study

The CONTROLRISK study was designed to determine the cardiovascular risk profile of the hypertensive population attended at primary care and specialist setting in Spain and to investigate whether physicians stratify the risk correctly, according to the 2003 European guidelines. A total of 8920 patients were recruited from primary care (n=4485) and specialist outpatient clinic (n=4435). The age criteria was 62.6+/-11.1 years; 51.6% were women. No differences were observed in the severity of hypertension. More than 85% presented other cardiovascular risk factors, similarly in both groups. Target organ damage (TOD) and associated clinical conditions (ACC) were more frequent in specialist setting (57.6 vs 34.3% and 39 vs 28.7%, both P<0.0001). The most common risk factor was age. The most frequently reported TOD was left ventricular hypertrophy (42.3 and 22.1%; P<0.0001). Ischemic heart disease was the most common ACC (21.5 vs 13.1%; P<0.0001). The risk profile was significantly higher in specialist population (75.1 vs 60.3% of patients belonged to high- or very high-risk groups). Specialists and primary care physicians stratified only 54.6 and 48% of their patients correctly, respectively (P<0.05). Both, specialists and general practitioners (GPs) strongly underestimated the risk. Very high-risk patients were adequately assessed only in 44.9% of cases by specialists and in 25.3% by GPs (P<0.001). More than half of the hypertensive patients attended by GPs in Spain belong to the high- or very high-risk groups. GPs and specialists tend to underestimate the cardiovascular risk in daily clinical practice, mainly in very high-risk patients.

Lercanidipine is an effective and well tolerated antihypertensive drug regardless the cardiovascular risk profile: The LAURA study

To determine whether the antihypertensive effectiveness of lercanidipine was independent of the different cardiovascular risk levels. Patients with treated or untreated mild-to-moderate essential hypertension were included in a multicentre, prospective, non-comparative, open-label study. Patients received lercanidipine (10 mg/day, uptitrated to 20 mg/day) during 6 months. A total of 3175 patients, age 63 +/- 10 years, 51% women, were included. The cardiovascular risk was low in 237 patients, medium in 1396, high in 722, and very high in 820. At baseline, blood pressure (BP) was 159.5 +/- 11.7/95.2 +/- 7.4 mmHg. BP was progressively higher according to increase in cardiovascular risk. After 6 months of treatment, BP was 136.0 +/- 9.7/79.7 +/- 6.8 mmHg. The decrease in systolic BP and diastolic BP at each follow-up visit compared with baseline was statistically significant both in the intergroup and intragroup comparisons (p < 0.001). Mean decreases of systolic blood pressure (SBP) and diastolic blood pressure (DBP) were -18.5/-13.8 mmHg in the low risk group, -23/-15.2 mmHg in the medium risk group, -24.4/-16.1 mmHg in the high risk group, and -27.4/-17.4 mmHg in the very high risk group. Most frequent side effects were oedema (5.1%), headache (3.3%), flushes (2.5%), and asthenia (1%). Only 1.7% of patients discontinued antihypertensive medication because of adverse events. Tolerability of lercanidipine was independent of the cardiovascular risk group. Lercanidipine was effective and well-tolerated in patients with mild-to-moderate hypertension in the daily practice. The effectiveness and safety of the drug were independent of the degree of cardiovascular risk.

Photoacoustic determination of iron in corn meal

We report here on the use of the photoacoustic technique for the determination of low concentrations of total iron in corn meal samples. The determination of this element in food is of considerable interest because several foods are currently enriched with it at proper levels in order to increase the resistance of people, after consumation, to several diseases, such as anemia. The proposed technique is based on an open photoacoustic cell configuration in conjunction with a suitable colorimetric method. We applied it to a measurement of the total iron concentration in corn meal samples. The results agree very well with those obtained using a conventional spectrophotometric method, showing the possibilities of new experimental methodologies based on photothermal methods to perform this kind of study, with the advantage of a higher sensitivity and increment of the range of appreciable absorbance.

Magnetic resonance study of the pancreatic duct

AIM

to prospectively determine the diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) in the evaluation of the normal and diseased pancreatic duct.

METHODS

patients seen during a 6-month period with a diagnosis of biliary tract or pancreatic disease underwent endoscopic retrograde cholangiopancreatography (ERCP) after a previous MRCP. The pancreatic duct was evaluated with both techniques in 37 patients.

RESULTS

the pancreatic duct appeared normal in ERCP in 27 patients, and also appeared normal in MRCP in 25 of these patients (specificity 93%). ERCP showed moderate-severe pancreatic duct dilation in 8 patients, in whom the same diagnosis was reached with MRCP (sensitivity 100%). The causes of dilation were chronic pancreatitis (2 patients), pancreatic cancer (3 patients) and ampullary tumor (2 patients); in 1 patient the findings with both techniques were suggestive of neoplasm of the head of the pancreas or focal chronic pancreatitis. Pancreas divisum was diagnosed in 2 patients by both methods, and the predominant dorsal duct as well as the ventral duct were visualized by MRCP.

CONCLUSIONS

MRCP is an accurate technique for evaluating the normal or diseased pancreatic duct, and for determining the underlying disease.

Prospective epidemiological study of invasive Haemophilus influenzae disease in adults

The incidence and characteristics of invasive Haemophilus influenzae disease were studied in 43 adult patients admitted to the acute care hospitals in El Vallés County (Barcelona, Spain) between January 1987 and June 1992. The annual incidence of Haemophilus influenzae disease was 1.2 per 100,000 inhabitants. Pneumonia occurred in 24 patients, meningitis in five, intraabdominal infections in three, obstetric infections in two, epiglottitis in two and cellulitis in one. In six patients the source of infection was unknown. Ten (23%) of the infections were hospital acquired. Underlying conditions were diagnosed in 30 (70%) patients. Nontypeable Haemophilus influenzae strains predominated in all adult age groups. Sixty-one percent of type b and 34% of nontypeable strains were ampicillin resistant (p = 0.08). Multiple antibiotic resistance was also high among type b (53%) and nontypeable (18%) strains. The mortality rate was significantly higher in patients with pneumonia, bacteremia from an unidentified focus or shock at presentation.

[The analgesic and anti-inflammatory effects of Drymonia serrulata (Jacq.) Mart]

The authors experimentally demonstrated that an aqueous fraction of Drymonia serrulata (Jacq.) Mart. has peripheral, but not central, analgesic activity, and that it also has a dose-dependent anti-inflammatory activity at 24 and 96 hours. The experimental results indicate that the etnomedical use of this plant by the Guaymi Indians may have some scientific validity

Pathogenic and free-living amoebae isolated from swimming pools and physiotherapy tubs in Mexico

A protozoological survey was done to isolate free-living amoebae from swimming pools and physiotherapy tubs in Mexico City. Amoebae were isolated by culture in nonnutritive agar medium combined with Escherichia coli. Identification of the isolates was done by morphology using specialized taxonomic keys and by isoelectric focusing of total proteins and isoenzymes in agarose. Pathogenicity of the isolates was determined in 3-week-old mice by intracerebral and intranasal inoculations. Statistical tools were used to determine the existence of significant differences on the incidence and diversity of the isolates in relation to the two types of water bodies analyzed. Water and environmental temperatures, pH, and chloride concentrations were determined at each sampling site. Twenty-nine amoebic strains from eight genera were isolated. Most frequently found were specimens of the genera (Acanthamoeba (with four pathogenic strains), Vahlkampfia, Hartmannella, and Naegleria. Amoebae were isolated more frequently in spring and summer, and could not be recovered from pools with chloride levels of 5.31 mg/ml or more. This survey demonstrates that chloride concentrations commonly used in recreative pools and therapy tubs are not sufficient to eliminate viable cysts of most free-living amoebae. Significantly higher numbers of isolates were retrieved from the pools than from the tubs.

[Diagnosis, prevention and treatment of endodontic exacerbations]

Purpose of this paper is to undertake a bibliographical review on the diagnosis, prevention and treatment of pain in endodoncy, in order to provide the reader with an updated guide on the clinical control of pain of dental origin.

Sleep patterns in the bird Aratinga canicularis

Behavioral and electrophysiological features of sleep and wakefulness were studied in chronically implanted adult parakeets, Aratinga canicularis. Four states of vigilance were observed: (1) Wakefulness. It is divided into active and passive. During this state there are generalized motor manifestations which are more frequent and intense in active wakefulness. Cerebral activity is fast and of low amplitude. (2) Drowsiness. Motor activity is notably lower. Blinkings become progressively less frequent. Electroencephalographic patterns are constituted by waves of variable amplitude and frequency. It constitutes 40.7% of the nychthemeral cycle. (3) Slow Wave Sleep (SWS). Animals remain immobile with eyes closed and eye movements are at their lowest frequency. Cerebral activity is slow and of high amplitude. It constitutes 14.7% of the nychthemeral cycle. No sleep spindles are present. (4) Paradoxical sleep (PS). The bird's head tends to drop due to additional muscular relaxation; its eyes remain closed but there are bursts of ocular movements. The EEG is similar to that of wakefulness. This state lasts 7.14 sec on average and occupies 1.98% of the nychthemeral cycle. It is always preceded by SWS. The absence of sleep spindles could be due to the differences in cerebral development compared with mammals.

Sleep patterns in a chelonian reptile (Gopherus flavomarginatus)

Individuals of Gopherus flavomarginatus, previously adapted to experimental conditions were chronically implanted for polygraphic recordings. Four different states of vigilance were observed:. Active wakefulness, quiet wakefulness, quiet sleep and active sleep. EEG was polymorphic and irregular showing a decreasing tendency in frequency and amplitude when passing from wakefulness to quiet sleep. Heart rate decreased with sleep but it was slightly higher during active sleep than quiet sleep. Motor automatisms were present during active sleep being sometimes accompanied by ocular movements. This sleep always appeared after long periods of quiet sleep. Its average duration from animal to animal varied between 9.15 and 13.62 sec. Reaction threshold increased during sleep. The conclusion is that Gopherus flavomarginatus shows two phases of sleep similar to slow and paradoxical sleep in mammals.

Isolation and identification of Rickettsia rickettsii from the rabbit tick (Haemaphysalis leporispalustris) in the Atlantic zone of Costa Rica

During the ecological studies done in Costa Rica on Rocky Mountain spotted fever, we have been able to isolate 2 strains of rickettsiae from the rabbit tick Haemaphysalis leporispalustris, indistinguishable from R. rickettsii isolated from humans in our country. Moreover, serological evidence of this agent was demonstrated in convalescent guinea pigs and in the sera of the wild rabbit (Sylvilagus braziliensis).

[Tomographic densitometry of the human thorax]

We show the first clinical images obtained by a new tomographic system based on the detection of the scattered gamma photons of 99mTc by the chest tissues. These images show satisfactory contrast and tomographic effect on the half-chest near the radioactive source. Both effects tend to decrease on the contralateral half-chest. The images rendered important data in differential diagnosis of perfusion defects evident by lung scintigraphy with macroaggregated albumin labeled with 99mTc. Pulmonary density was normal and homogeneous in a healthy volunteer and also in a patient with pulmonary embolism. It demonstrated a hyperdense pulmonary mass in a patient with tumor of the right lung, which produced a perfusion defect evident in the conventional lung scintiscan, and a shadow in the gamma ray transmission image.

[Experimental evaluation of a tomographic system of the thorax by detection of the dispersion of technetium-99m radiation]

Based on a previous theoretical study, a simple device for the acquisition of bidimensional tomographic images of the human chest densitometry was designed. A radioactive linear source (99mTc) was adapted to the lateral aspect of a gamma camera detector in order to register only those photons scattered at 90 degrees. Resulting images from a liver phantom stuffed with saw dust, showed an evident tomographic effect and a satisfactory contrast between the structures sited at less than 20 cm from the source. These effects tend to decrease with distance. The causes of these deficiencies of the system and their possible corrections are discussed.

[Formation and migration of radioactive microemboli to the lung during radiovenography]

Two patients with lower extremity thrombophlebitis were studied by radionuclide venography with macroaggregated albumin labelled with 99mTc. Data analysis was performed with a new method. It generated sequential series of imagen (1-2 sec/frame) of the transit of the tracer through leg, thigh, and abdomen, allowing a more precise definition of temporal changes on regional radioactivity. This method rendered the first real evidence of the binding of the tracer to pre-existent venous thrombi, of the dislodgement of these and their gradual fragmentation during their transit to the lungs. The patients had no complaints during or after the study. Lung scanning, performed 24 hours later, showed slight alteration on regional lung perfusion in one case, and none in the other. It is concluded that radioactive microemboli to the lungs is a minor complication of radionuclide venography, which does not justify prevention. This could only nullify the sensitivity of the procedure.

Detection of signs of estrus in the charolais cow and its Brahman cross under continuous observation

In order to study the characteristic signs of an induced estrus in beef cattle maintained in the tropics, 31 animals, 16 pure Charolais and 15 Charolais/Brahman cross, were continuously observed during the first 100 hours following prostaglandin injection. The animals were pastured in a field of approximately 3 hectares. A highly significant relationship (P < 0.01) seemed to exist between behavioural tendencies and the interval following the onset of estrus. Behaviour included butting, attempts to mount, smelling of genitalia (active) and allowing to be mounted and have genitalia smelled (passive). No consistant pattern of sexual activity could be established since some animals were more active than others. Mounts were observed to occur between 6 and 9 in the morning (33%), 9 and 12 at night (16%) and midnight and three in the morning (13%). Differences existed between the Charolais and the Brahman cross with respect to the number of mounts (P < 0.05) and in the response to an induced estrus (P < 0.05). No correlation was found between grazing habits and sexual activity, the former expressed as the number of animals standing up during each hour.

Rotavirus viral RNA electrophoresis in hospitalized infants with diarrhea in Santiago, Chile

Viral RNA electrophoresis technique was used to detect rotavirus in 226 children under 2 years of age with acute diarrhea, admitted to the Roberto del Río Hospital in Santiago, Chile, during the period of June 1979 through May 1980. A group of 50 children included in the aforementioned sample, admitted in winter, was compared with a control group of 25 infants without digestive pathology. In these groups, rotavirus was detected in 20 out of 50 children with diarrhea (40%) but not in the controls (0%). A positive diagnosis of rotavirus was found in 66 out of the total of 226 patients (29.2%); its monthly distribution ranged between a maximum of 83.3% (June) and a minimum of 11.1% (October).