Study of macro and microelements in fish from the Cienfuegos Bay. Relationship with its content in sediments.

Thirteen microelements (Al, As, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Ti, V, and Zn) and four macroelements (Ca, K, Mg, and Na) were determined in the edible muscle tissue of fish in Cienfuegos Bay. Eight species, Albula vulpes, Diapterus rhombeus, Gerres cinereus, Haemulon carbonarium, Haemulon sciurus, Micropogonias furnieri, Kyphosus sectatrix, and Lutjanus cyanopterus were studied. The total concentrations and extracted concentrations using HCl were also determined in sediments. The quality of the analysis was guaranteed by validating the used analytical methods with certified reference materials of fish and sediments. The high content of macroelements confirmed the importance of fish as a valuable source of food for the local population. New information is provided on bioaccumulation of toxic elements As, Cd, Cu, Zn, and Cr in fish of the bay, with concentrations that overcame the local or international maximum allowable levels for human consumption in most samples analyzed. A high correlation between the content of toxic elements As, Cd, Zn, and macroelement K in fish and its concentration extracted from sediments using the HCl extraction method was observed.

A comparison between different parameters in F-wave studies.

Ulnar nerve F-waves were studied in 23 healthy volunteers and 27 diabetic patients. Latencies and chronodispersion were analyzed in each group. In the diabetic group all the parameters were normal in 14 patients (52%) and in 13 (48%) at least one parameter was altered. In these patients the most frequently altered parameter was the maximum latency (92%), followed by mean latency (85%), minimum latency (54%) and chronodispersion (54%). These findings suggest that maximum and mean latencies are better parameters to be analyzed in ulnar F-wave studies than minimum latency.

Quantitative analysis of EEG background activity in patients with rolandic spikes.

OBJECTIVE: The aim was to compare the background activity, through quantitative EEG analysis, of patients with rolandic spikes and normal age-matched controls. MATERIAL AND METHODS: Twenty-one channel EEG of 23 children with rolandic spikes and 39 normal children, with ages ranging from 7 to 12 years, were submitted to quantitative analysis (FFT) of discharge-free epochs. Patients and controls were divided in groups according to age (7-9 and 10-12 years old). Delta, theta, alpha and beta frequency ranges were compared between groups for all electrode positions. RESULTS: Comparing normals, the 7-9 years old group showed power reduction in the alpha and beta ranges. Comparing patients and normal age-matched groups, the patients showed power increase, at all frequency ranges in the 7-9 years old group and at delta and theta frequency ranges in the 10-12 years old group. CONCLUSIONS: Our findings agree with recent evidences that these children may differ from normal (besides the eventual occurrence of seizures); but they also suggest that these differences can be related to immaturity and not necessarily related to the epileptiform discharge.

Flow-injection spectrophotometric determination of ascorbic acid in pharmaceutical products with the Prussian Blue reaction.

A lot of modern analytical strategies for exploiting chemistries have been developed by using flow-injection analysis. However, even after 20 years of flow-injection evolution, there still are new quantitative procedures being established using old qualitative assays. The formation of Prussian Blue is a classical test to detect Fe(2+) using hexacyanoferrate(III) as a precipitating reagent. This reaction was evaluated for spectrophotometric determination of ascorbic acid employing Fe(3+) and hexacyanoferrate(III) as chromogenic reagents. An excess of the complexing anion avoids the formation of precipitate and forms a deep blue solution when Fe(3+) is reduced to Fe(2+) by ascorbic acid. The maximum absorbance of the colored complex occurs at 700 nm and the molar absorptivity is 3.0 x 10(4) 1 mol(-1) cm(-1). Under flow-injection conditions the Prussian Blue reaction was employed with an intermittent flow of an oxalate alkaline solution for removing the colored product adsorbed on tube and flow-cell walls. Reference solutions containing 5.0 x 10(-6)-1.0 x 10(-4) M of ascorbic acid were employed to obtain the analytical curve (r = 0.9999). For all solutions the relative standard deviation was lower than 1.0% (n=10). Results obtained for ascorbic acid determination in pharmaceutical products (Cewin, Redoxon and Cebion) are in good agreement with those obtained by using a flow-injection procedure involving the reaction between triiodide and ascorbic acid. The sampling frequency is 140 h(-1) and only 430 microl of reagents is consumed in each determination.

Flow injection spectrophotometric determination of nitrate in electrolyte of lead-acid batteries.

Electrolytes of lead-acid batteries can contain several impurities that reduce battery performance and lifetime. Nitrate ions are among these species because they can be reduced to ammonium in the lead electrode. In this work, an analytical method was developed to determine this anion in electrolytes of batteries used in telephone systems, in which nitrate concentration must be lower than 10 mg l(-1). The procedure consists in the reduction to nitrite in a copperized cadmium column followed by Griess's modified reaction. Due to the high sensitivity of this methodology, a large dispersion flow diagram (dispersion coefficient = 27.8) was projected. Thus, it was possible to eliminate the Schlieren effect and to obtain a NH (3)NH (+)(4) buffer in the sample zone in a suitable pH for reduction reaction (pH congruent with 8). Negative interference due to iron(III) was overcome by addition of excess iron (200 mg l(-1)). A relocatable filter was used to remove iron(III) hydroxide precipitate. This avoided adsorption on the surface of the filings and increase of back pressure. The analytical frequency is 80 measurements/h and the detection limit was estimated as 0.3 mg l(-1) in a 99.7% confidence level. A 2.2% relative standard deviation was obtained in a repeatability study (n = 10) by using a 25 mg l(-1) nitrate solution in a 3.6 mol l(-1) sulfuric acid medium. Recoveries from 95.5 to 104% were obtained by spiking 5.00 or 10.0 mg l(-1) of nitrate in samples of battery electrolyte.

Flow injection potentiometric determination of saccharin in dietary products with relocation of filtration unit.

A flow injection potentiometric procedure for saccharin determination in dietary products is proposed. Saccharin is precipitated as mercurous saccharinate and the excess of the mercurous cation is potentiometrically measured using a silver wire coated with a mercury film as the working electrode. A filter unit is used to avoid contact between the precipitate and the electrode surface. With relocation in the flow manifold, the accumulated precipitate is removed on-line. Sucrose, glucose, aspartame, sodium cyclamate and sodium benzoate do not interfere when present in amounts similar to those observed in commercial products. Results are comparable with those obtained by UV-spectrophotometry and the correlation coefficient between methods is equal to 0.9930. A linear relationship between DeltaE (mV) and the logarithm of saccharin concentration was obtained in the saccharin concentration range 2 x 10(-3) - 1 x 10(-2)M. The sampling frequency is 60/hour and only 0.76 mg of Hg(2+)(2) is consumed in each determination.

Asynchronous merging zones system: spectrophotometric determination of Fe(II) and Fe(III) in pharmaceutical products.

An asynchronous merging zones was proposed with simultaneous introduction of the sample and of the modifier reagent, ascorbic acid in the studied case, for sequential determination of Fe(II) and Fe(III) in pharmaceutical products. The sample and reagent attained a merging point at different times owing to the use of a delay reactor in the reagent channel. By inserting a large sample and controlling the dispersion in the flow system, Fe(II) and Fe(III) were sequentially measured in the front and in the rear of the sample zone, respectively. The results obtained for Fe redox speciation in pharmaceutical products are in agreement at a 95% confidence level with those obtained with a manual spectrophotometric procedure. The analytical frequency with the proposed flow analysis system was 54 samples h(-1), i.e. 108 determinations h(-1).

Determination of ytterbium in animal faeces by tungsten coil electrothermal atomic absorption spectrometry.

A method for ytterbium determination in animal faeces by tungsten coil electrothermal atomic absorption spectrometry (TCAAS) was developed. Faeces were dry-ashed in a muffle furnace, the ashes were treated with hydrochloric acid, and 10 mul of sample solution were delivered into 150-W tungsten coil atomizer. A matrix-matching procedure employing a 66-s heating program proved to be efficient for obtaining accurate results. Characteristic mass and detection limit were 7.1 pg and 0.35 mug g(-1) Yb, respectively. The tungsten coil atomizer lifetime exceeded 300 firings with digested solutions and R.S.D. of measurements was 1.9% after ten consecutive injections of 10.0 mug l(-1) Yb. Accuracy of the proposed method was assessed by employing a graphite furnace atomic absorption spectrometric procedure. Application of the paired t-test did not reveal any significant difference for ytterbium contents determined by both methods at 95% confidence level. It was demonstrated that the proposed procedure can successfully be used for evaluation of kinetic passage rate of feed through digestive tract of animals.

Determination of cadmium in hair and blood by tungsten coil electrothermal atomic absorption spectrometry with chemical modifiers.

Three chemical modifiers ((NH(4))(2)HPO(4), NH(4)H(2)PO(4), and Pd as Pd(NO(3))(2)) were evaluated for the determination of Cd in acid-digested solutions of hair and blood using electrothermal atomic absorption spectrometry in a tungsten coil atomizer (TCA). All modifiers caused some thermal stabilization of Cd when compared to the behavior observed in nitric acid medium. The best effects were observed in 15 mug ml(-)(1) Pd medium; the characteristic mass of Cd was 0.3 pg and the method detection limits were 0.009 mug g(-)(1) in hair and 0.2 mug l(-)(1) in blood. In addition to a slight thermal stabilization effect, Pd also increased the sensitivity for Cd by ca. 40% and the tungsten coil lifetime by 20% (i.e. from 300 to 360 heating cycles), reduced background signals, and eliminated condensed phase interferences caused by concomitants. The accuracy (3.2% as mean relative error in the Pd modifier) was checked for the determination of Cd in acid-digested solutions of certified reference materials of human hair and blood and by recoveries of Cd in spiked hair and blood samples by both TCA and a graphite furnace procedure. All results obtained in chemical modifiers are in agreement at a 95% confidence level.

Atomization of Al in a tungsten coil electrothermal atomic absorption spectrophotometer.

Electrothermal atomic absorption spectrophotometry of Al in a tungsten coil atomizer was evaluated and applied for its determination in hemodialysis fluid. The system was mounted on a Varian Spectra AA-40 spectrophotometer with continuum background correction and all measurements, in peak height absorbance, were done at 309.3 nm. The purge gas was a mixture of 90% Ar plus 10% H(2). Observation height, gas flow, drying, pyrolysis and atomization steps were optimized. The heating program was carried out by employing a heating cycle in four steps: dry, pyrolysis, atomization and clean. The determination of Al in hemodialysis solutions was performed by using a matrix-matching procedure. Al in hemodialysis solutions was determined by TCA and by electrothermal atomization with a graphite tube atomizer. There is no differences between results obtained by both methods at a confidence level of 95%. The characteristic mass of Al by using the TCA was 39 pg and the detection limit was 2.0 mug l(-1).

Determination of cadmium and lead in mussels by tungsten coil electrothermal atomic absorption spectrometry.

In this work it was evaluated the determination of Cd and Pb in mussels by tungsten coil electrothermal atomic absorption spectrometry (TCA-AAS). A critical and comprehensive study of the effects caused by Pd, Mg, ascorbic acid, and binary mixtures of these compounds on the atomization of Cd and Pb in acid digested solutions of mussels was performed. Palladium and mixtures containing it were useful to increase sensitivity and thermal stability of Cd and Pb. Additionally, the coil lifetime was increased and the background signals were decreased in these modifiers. All these favorable effects were analytically exploited to determine Cd and Pb in samples of mussels. The proposed methodology was validated using two certified reference materials (oyster tissue and mussel). No statistical difference was observed between determined and certified values at a 95% confidence level. Cadmium and Pb in Chilean bivalve mussels were determined by TCA and by graphite furnace-AAS. Again, the results showed statistical agreement.

Some functional observations related to the N18 component of the median nerve SEP.

This work describes the results of two experimental procedures related to the short latency median nerve somatosensory evoked potentials. In the first one, it was possible to show that there is a different rate of increase in the amplitude of the different components related to different intensities of stimulation. In the second one, the simultaneous stimulation of the median and the ulnar nerves disclosed an occlusive interaction which was larger for the N18 than for the other components. These results may be a support to the hypothesis that the N18 component generator is related to the mechanism of presynaptic inhibition within the cuneiform nucleus.

Nerve conduction study of the medial and lateral plantar nerves.

The medial and lateral plantar nerves may be evaluated through the recordings of the compound sensory nerve action potentials (CSNAP), compound mixed nerve action potentials (CMNAP) and compound muscular action potentials (CMAP). As some of these potentials are not easily and always obtainable in normal individuals, our purpose was to verify the consistency of these potentials for the study of these nerves. Fifty-one normal adult volunteers were examined. The CSNAP, CMNAP and CMAP, related to the medial and lateral plantar nerves were evaluated bilaterally. CSNAP were not obtained in 7.8% and in 17.6% from the medial and lateral plantar nerves respectively. CMNAP from the lateral plantar nerve were not obtained in 15.6%. CMNAP from the medial plantar nerves and CMAPs from the abductor hallucis and abductor digiti quinti were obtained for all nerves tested. Our results, therefore, suggest that these last 3 parameters are the ones more reliable for clinical application.

F-waves and conduction velocities range.

A controversial aspect in F-wave studies is if these potentials are generated preferentially by large motoneuron or by motoneuron of all sizes. The purpose of this work is to compare the maximum and minimum conduction velocities of the fibers that generate the M-wave with the maximum and minimum conduction velocities of the F-waves elicited by ulnar nerve stimulation. There were no significant differences between maximum velocities. However, minimum F-wave velocity was significantly higher than minimum conduction velocity, suggesting that the F-waves registered were preferentially generated by the fastest conducting axons.

[A review of technical and physiological aspects of F-wave studies and analysis of the data obtained in a group of diabetic patients]. / Revisão relacionada a alguns aspectos técnicos e fisiológicos das ondas F e análise dos dados obtidos em um grupo de indivíduos diabéticos.

We reviewed some physiological aspects of the F-wave studies, mainly related to the motoneurone sizes involved in the generation of this potentials and the number of stimuli necessary to analyze the F-wave parameters. F-wave latencies and F-wave conduction velocities obtained in a group of normal volunteers and in a group of diabetic patients are analyzed.

[Normal values of neural conduction velocity in a group of 101 subjects]. / Valores normais das velocidades de condução nervosa em um grupo de 101 pessoas.

Motor and sensory nerve conduction velocities were analysed in a group of 101 normal Brazilians. The normal values were obtained considering the group age, the distal and proximal segments of each nerve, the differences in the right and left side for each nerve. A significant decline in the conduction was found for the elderly aged group.

[Rhabdomyolysis and myoglobinuria: report of an acute case with favorable outcome]. / Rabdomiólise e mioglobinúria: relato de caso agudo com boa evolução.

A case of paroxysmal myoglobinuric myopathy diagnosed by urinary protein electrophoresis is reported. Electromyograph (EMG) study done 20 days after onset of the symptoms demonstrated a polimyositic feature with normal motor and sensitive nervous conduction pattern. A biopsy of the left deltoid muscle performed 3 days after the EMG showed only an unspecific inflammation. The treatment included bed rest, parenteral fluids administration in excess (about 3,000 ml per day) and urinary alkalinization. Recovery started on the 2nd day of hospitalization when the patient showed progressive decrease in pain and weakness; furthermore the patient reacquired his mobility. The myoglobinuria start diminishing in intensity on the third day. The clinical picture of the patient continued to improve in the next 2 weeks, and slow recovery of the muscular strength occurred during the following two months of convalescence. In the present case we were not able to establish the etiology of the illness. Nevertheless the clinical history suggests that infection, allergy and/or parenteral drug administration have had some role in precipitating the disease. This case report reinforces the concept that it is necessary an early and precise diagnosis of this syndrome followed by an adequate therapeutic approach avoiding the unnecessary use of drugs which "per se" could aggravate the disease.

[Electroneurography of the facial nerve: methods of stimulation and records]. / Eletroneurografia do nervo facial. Métodos de estimulação e registro.

In this study it is, intended to establish the more appropriate points to register the compound action potential from m. frontalis m. orbicularis oculi and nasolabial fold muscles. The optimum site for stimulating electrodes and differences between the first and the last compound action potentials after 20 consecutive stimuli delivered at 1 Hz were analysed.

[Evoked potentials by median nerve stimulation: comparison of central conduction time defined by different measure points]. / Potencial evocado por estimulação do nervo mediano. Comparação do tempo de condução central definido por diferentes pontos de medida.

After stimulation of the right median nerve in 20 normal adult volunteers interpeak latency N13-N20 and the difference in onset latency of the components N11-N20 are compared. A fractionation of the last measure was made at the onset of the P13-14 complex. The results concur with the ones in the literature, and it has been observed that all points measured could be obtained without significant difference on the C6-FZ and P3-FZ montages.

[Progressive extrinsic ophthalmoplegia; case report]. / Oftalmoplegia extrínseca progressiva; registro de um caso.

A case of progressive ophtalmoplegia and ptosis affecting a 12 year old boy is reported. A miopatic pattern was detected by the electromyography, the cerebrospinal fluid showed an increase of the protein content and retinal pigmentary degeneration was detected. This findings call the attention for a more widespread degenerative disorders affecting not only the muscular sistem but other organs as well.