Search PubMed⌕ Search

Biomedical subjects

A Polo

Publications and source records attributed to A Polo.

At least 19 recordsLinked to original sources
PubMed2005

Copper(II) complexation by humic and fulvic acids from pig slurry and amended and non-amended soils.

The effect of the consecutive annual additions of pig slurry at rates of 0 (control), 90 and 150 m3 ha(-1) y(-1) over a 4-year period on the binding affinity for Cu(II) of soil humic acids (HAs) and fulvic acids (FAs) was investigated in a field plot experiment under semiarid conditions. A ligand potentiometric titration method and a single site model were used for determining the Cu(II) complexing capacities and the stability constants of Cu(II) complexes of HAs and FAs isolated from pig slurry and control and amended soils. The HAs complexing capacities and stability constants were larger than those of the corresponding FA fractions. With respect to the control soil HA, pig-slurry HA was characterized by a much smaller binding capacity and stability constant. Amendment with pig slurry decreased the binding affinity of soil HAs. Similar to the corresponding HAs, the binding affinity of pig-slurry FA was much smaller while that of amended-soil FAs were slightly smaller when compared to the control soil FA. The latter effect was, however, more evident with increasing the amount of pig slurry applied to soil per year and the number of years of pig slurry application.

Animals↗
PubMed2003

Peripheral and segmental spinal abnormalities of median and ulnar somatosensory evoked potentials in Hirayama's disease.

OBJECTIVES: To investigate the origin of juvenile muscle atrophy of the upper limbs (Hirayama's disease, a type of cervical myelopathy of unknown origin). SUBJECTS: Eight male patients were studied; data from 10 normal men were used as control. METHODS: Median and ulnar nerve somatosensory evoked potentials (SEP) were recorded. Brachial plexus potentials at Erb's point (EP), dorsal horn responses (N13), and subcortical (P14) and cortical potentials (N20) were evaluated. Tibial nerve SEP and motor evoked potentials (MEP) were also recorded from scalp and spinal sites to assess posterior column and pyramidal tract conduction, respectively. RESULTS: The most important SEP findings were: a very substantial attenuation of both the EP potentials and the N13 spinal responses; normal amplitude of the scalp N20; and normal latency of the individual peaks (EP-N9-N13-P14-N20). Although both nerves were involved, abnormalities in response to median nerve stimulation were more significant than those in response to ulnar nerve stimulation. There was little correlation between the degree of alterations observed and the clinical state. Latencies of both spinal and cortical potentials were normal following tibial nerve stimulation. The mean latency of cervical MEP and the central conduction time from the thenar eminence were slightly but significantly longer in patients than in controls. CONCLUSIONS: The findings support the hypothesis that this disease, which is clinically defined as a focal spinal muscle atrophy of the upper limb, may also involve the sensory system; if traumatic injury caused by stretching plays a role in the pathogenesis, the damage cannot be confined to the anterior horn of the spinal cord.

Adolescent↗
PubMed2001

A somatic and germline mosaic mutation in MPZ/P(0) mimics recessive inheritance of CMT1B.

OBJECTIVE: To identify the molecular basis of a demyelinating Charcot-Marie-Tooth disease type 1 (CMT1) with presumed autosomal recessive inheritance. BACKGROUND: CMT1, an inherited motor and sensory neuropathy with low nerve conduction velocities, is caused by dominantly inherited mutations in the genes of the peripheral myelin protein 22 (PMP22), myelin protein zero (MPZ/P(0)), and early growth response 2 transcription factor (EGR2/Krox-20). PATIENTS AND METHODS: Two young sisters born of clinically and electrophysiologically healthy parents had a severe CMT1 neuropathy of presumed autosomal recessive inheritance. The older sister underwent a nerve biopsy. The authors analyzed PMP22, MPZ/P(0), and EGR2/Krox-20 by automated direct nucleotide sequencing. For rapid mutation detection, they determined the restriction-fragment-length polymorphisms for TaqI in the fluorescein-labeled target DNA sequence amplified by PCR. RESULTS: Nerve biopsy disclosed a demyelinating and remyelinating neuropathy with onion bulb formations. Both sisters had a novel heterozygous G308-->A transition of MPZ/P(0) without any mutation of PMP22 or EGR2/Krox-20. The G308-->A transition was a nonconservative mutation that changed a glycine into a glutamate at the amino acid residue 74 in the extracellular domain of the mature MPZ/P(0). None of 50 healthy controls had the mutation. The healthy mother had a low amount of the mutation in blood (congruent with 20%) as well as in skin, buccal epithelium, and hairs (30%). Because the healthy mother carried clones of somatic mutant cells and had transmitted the G308-->A transition to the affected daughters, she also harbored germline mutant cells. CONCLUSION: In hereditary demyelinating neuropathies, somatic and germline mosaicism of dominant mutations in the myelin protein genes may mimic autosomal recessive inheritance.

Adolescent↗
PubMed2001

Influence of one or two successive annual applications of organic fertilisers on the enzyme activity of a soil under barley cultivation.

The effect of cow manure and two rates of addition of municipal solid waste (MSW) compost on the enzymatic activity of a soil supporting barley cultivation was studied and compared with mineral fertilisation (MF). The experiment was carried out in unirrigated land in field conditions for two years. One set of plots was fertilised only once, at the start of the experiment, while another set of plots was fertilised annually (before each sowing). In general, the organic amendments stimulated soil enzyme activity but mineral fertilisation did not. The annual addition of large quantities of MSW compost, in general, led to lower levels of enzyme activity than similar rates of amendment in the plots receiving a single addition, probably because of the toxic effect which the heavy metals incorporated with the MSW compost had on microbial development. In the second year, plot receiving a single application of organic amendment showed higher protease hydrolysing casein, beta-glucosidase and dehydrogenase activities than control or soil with mineral fertilisation. This implied that the addition of organic waste, and particularly MSW compost, had a catalysing effect in the soil which lasted for the following years. Barley yields obtained with organic amendments were, in general, similar to, or even higher, than those obtained with mineral fertilisation. The annual addition of high doses of compost had an inhibitory effect on enzyme activity and barley yield (compared with the results obtained with the low addition of compost) due to the negative effect of the heavy metals incorporated with the compost.

Agriculture↗
PubMed2001

Pharmacological and dietary prophylaxis and treatment of acute actinic esophagitis during mediastinal radiotherapy.

Our purpose was to evaluate a pharmacological and dietary protocol of prophylaxis and treatment of acute actinic esophagitis during mediastinal radiotherapy. This phase II study was conducted on 29 patients affected by cancer not directly involving the esophagus. The irradiated volume included at least 10 cm of esophagus with a median dose of 46 Gy and the incidence of clinical acute esophagitis was scored with RTOG-EORTC tables. During the entire course of radiation therapy all patients were subjected to prophylaxis pharmacological therapy in addition to dietetic rules commonly used. All patients were evaluable, 9 (31%) had no acute esophageal toxicity, 20 (69%) had toxicity of degree 1, and no patient showed a toxicity of degree 2, 3, or 4, there were no toxicity-related related interruptions of the radiotherapy course. In conclusion, this low cost protocol seems to reduce the incidence and degree of acute radiation esophagitis (without added morbidity), compared with literature reports.

Acute Disease↗
PubMed2001

Electrophysiologic monitoring in neurointensive care.

Cumulative evidence of potential benefits of electroencephalography (EEG) and evoked potentials in the management of patients with acute cerebral damage has been confirmed. Continuous EEG monitoring is the best method for detecting nonconvulsive seizures and is strongly recommended for the treatment of status epilepticus. Continuously displayed, validated quantitative EEG may facilitate early detection of secondary cerebral insults and may play a decision-making role in the management of patients with head injury, stroke, or subarachnoid hemorrhage. Long-latency auditory evoked potentials and cognitive components constitute a new field of interest for the progress of comatose patients. Motor evoked potentials may become clinically important both in acutely injured and elective postoperative patients. In the neurointensive care units adequate techniques can be selected to answer targeted clinical questions. The efficacy can be improved by implementing educational projects based on ad hoc training of nurses and neurointensive care specialists.

Acute Disease↗
PubMed2000

A CLN2 gene nonsense mutation is associated with severe caudate atrophy and dystonia in LINCL.

Clinical features and results of the blood DNA analysis are reported of a child affected with a distinct phenotype of the late infantile form of neuronal ceroid-lipofuscinosis (LINCL). He was affected by microcephaly and hypotonia since the fourth month of life; acquisition of motor and language abilities was severely impaired, and a disorder of communication with stereotyped movements followed. By age four, he developed signs and symptoms of progressive myoclonic encephalopathy along with motor and cognitive deterioration. Extrapyramidal signs were associated with neuroradiological findings of marked atrophy of the caudate nucleus. Specific curvilinear bodies were observed in blood lymphocytes and skin biopsy. Homozygous, nonsense mutation in the CLN2 gene was found giving origin to an Arg208stop, which produces an early transcription termination with loss of translation of about 50% of the gene product. Any relationship between the severe clinical features of our patient and the homozygous mutation here reported must be investigated on a larger number of LINCL patients bearing the same mutation.

Atrophy↗
PubMed2000

Painless fractures and thermoregulation disturbances in sensory-autonomic neuropathy: electrophysiological abnormalities and sural nerve biopsy.

We describe the case of a young girl suffering from thermoregulation disturbances, painless fractures and arthropathy since early childhood. The patient was diagnosed as having a hereditary sensory autonomic neuropathy. Although needle EMG, conventional nerve conduction studies and somatosensory evoked potentials gave normal results, sympathetic skin responses (SSRs) were absent. Sural nerve biopsy showed a substantial reduction in the number of small myelinated and unmyelinated fibers. We emphasize the importance of SSR testing in revealing a condition which is otherwise difficult to identify by electrophysiological techniques. The combined evidence of functional and morphological findings is strongly suggestive of selective peripheral nerve involvement.

Adolescent↗
PubMed2000

Phytoavailability and extractability of potassium, magnesium and manganese in calcareous soil amended with olive oil wastewater.

Land disposal of olive oil wastewater using it as a soil amendment requires a knowledge of the effects that its application may produce on the status of the mineral nutrients in the plant-soil system. A pot experiment using calcareous soil was performed in a growth chamber to examine the effects of olive oil wastewater on the availability and postharvest soil extractability of K, Mg and Mn. The experiment included 6 treatments: two rates of olive oil wastewater, two mineral fertilizer treatments containing K (which supplied K in amounts equivalent to the K supplied by the olive oil wastewater treatments), a K-free mineral fertilizer treatment, and a control. The pots were sown with ryegrass as the test plant, harvesting 3 times at intervals of one month. Olive oil wastewater has demonstrated a considerable capacity for supplying K that can be assimilated by the plant, tending in fact to surpass the mineral potassium fertilizer tested. The application of olive oil wastewater tends to reduce the concentration of Mg in the plant, similarly to the effect of adding mineral potassium fertilizer. An enhancement of Mn availability takes place in the soil amended with olive oil wastewater, which on occasion has produced Mn concentrations in plant that could be considered phytotoxic or at least excessive. After harvesting, we observed an increase in the amount of exchangeable K in soil with added industrial wastewater. However, these increases are lower than those in soil treated with mineral potassium fertilizer. The levels of exchangeable, carbonate-bound, organic-bound and residual Mg in soil were higher in treatments incorporating olive oil wastewater than in those with added mineral K, with the opposite tendency occurring in the amount of Fe-Mn oxides-bound Mg in soil. Treatments based on olive oil wastewater, especially in high doses, increased the amount of exchangeable and carbonate-bound Mn in soil, in comparison with treatments adding mineral fertilizers with or without K. In contrast, the addition of industrial wastewater caused a drop in the amount of Fe-Mn oxides-bound and organic-bound Mn in soil.

Industrial Waste↗
PubMed2000

A comparative study of magnetic resonance cholangiography and direct cholangiography.

OBJECTIVE: Magnetic resonance cholangiopancreatography (MRCP) is a rapidly developing method for the noninvasive assessment of the biliary tree and pancreatic duct that obviates the need for contrast medium. We describe our experience with this new diagnostic imaging method in patients with obstruction of the biliary tree. We assessed both the location and cause of obstruction, and compared the results with direct cholangiography. METHODS: Between 1997 and 1998, 81 patients underwent MRCP at our facility. Two different image acquisition protocols (half-Fourier acquisition single-shot turbo spin-echo -HASTE- and rapid acquisition with relaxation enhancement -RARE-) for T2-weighted turbo spin echo sequences as well as cross-sectional fast multiplanar gradient-echo pulse (T1-weighted FL2D) and T2-weighted fast spin echo (T2 TSE) sequences were used. All patients underwent direct (either percutaneous or endoscopic retrograde) cholangiography or surgery for confirmation and/or treatment. The images obtained with MRCP were evaluated by two radiologists with expertise in biliary tree imaging who were unaware of the patient's clinical characteristics, and their diagnostic interpretations were compared with the findings obtained upon surgery or direct cholangiography. RESULTS: The sensitivity and specificity of MRCP in ruling out pathologies and detecting the presence of dilatation of the biliary tree were 100%. In assessing the level of the obstruction, sensitivity and specificity varied with location (intrahepatic/hilar, suprapancreatic, intrapancreatic or ampullary). Sensitivity in these locations was 100, 92, 69 and 86%, respectively, whereas specificity was 100, 94, 92 and 91%, respectively. In determining the cause of the obstruction, the results were variable depending on the cause: choledocholithiasis (sensitivity, 89%; specificity, 90%) malignant obstruction (sensitivity, 92%; specificity, 88%), benign stricture (sensitivity, 63%; specificity, 90%), and chronic pancreatitis (sensitivity, 50%; specificity, 99%). CONCLUSIONS: MRCP offered high diagnostic accuracy in the assessment of the occurrence and location of biliary obstruction. Sensitivity and specificity in establishing the cause varied, and were highest for choledocholithiasis and malignant obstruction. MRCP may be used instead of ERCP, which may then be reserved for patients who are likely to require surgery.

Adult↗
PubMed2000

[Neurophysiological monitoring during scoliosis surgery using controlled hypotension].

Controlled arterial hypotension understood to be a mean arterial pressure (MAP) between 55 and 60 mmHg is often used as a complementary technique in anesthesia even though it is not without complications and associated mortality even in young patients. During surgery to reduce scoliosis in a young boy, MAP fell to 60 mmHg accompanied by bilateral loss of sensory and motor evoked potentials (SEP and MEP). Detecting the absence of SEP and MEP allowed us to prevent medullar injury due to ischemia secondary to hypotension, once possible surgical or technical causes had been ruled out. We believe that monitoring SEP and MEP is useful not only to the surgeon but also to the anesthesiologist.

Adolescent↗
PubMed1999

Evidence for an abnormal cortical sensory processing in dystonia: selective enhancement of lower limb P37-N50 somatosensory evoked potential.

We evaluated brain stem P30, contralateral frontal N37, and the vertex-ipsilateral central P37, N50 somatosensory evoked potentials (SEPs) obtained in response to stimulation of the tibial nerve in 10 patients with idiopathic dystonia. Results were compared with those obtained in 10 healthy subjects matched for age and sex. The amplitude of the brain stem P30 potential and of the contralateral frontal N37 response in dystonic patients was not significantly different from that recorded in normal subjects. The vertex- ipsilateral central P37-N50 complex, which is thought to originate in the pre-rolandic cortex, was significantly enhanced in patients compared with the control group. These results suggest the enhancement of the vertex-ipsilateral central P37-N50 complex might reflect an abnormal response to somatosensory inputs of a precentral cortex which is excessively activated because of a disorder of the basal ganglia. Such inefficient sensory processing in motor areas might contribute to motor impairment in dystonia.

Adult↗
PubMed1999

Mechanism of binocular interaction in refraction errors: study using pattern-reversal visual evoked potentials.

In this study we sought to determine whether a natural condition involving fine discrimination, for example moderately severe myopia, might yield interesting information regarding the binocular interaction expressed by visual evoked potentials (VEPs). We studied ten normal subjects with a mild refraction deficits. Transient VEPs were elicited by monocular and binocular stimulation under conditions of natural and lens-corrected vision. The visual stimulus was a pattern-reversal checkerboard consisting of 15' and 40' checks. VEPs in response to binocular stimulation were compared with monocular VEPs. We plotted the monocular 'better-VEP' and 'worse-VEP' response, since significant differences between individual eye stimulations were present. We found no significant difference between the mean N75 and P100 latencies of the binocular VEP and the better monocular VEP, regardless of the check size used and of natural or corrected vision. Under all stimulus conditions, the mean amplitude of the N75-P100 of the binocular VEPs was also larger than the better monocular VEP response. The difference proved more significant when we stimulated our subjects with smaller squares and left vision uncorrected. The mean P100-N145 amplitude obtained with binocular stimulation was larger than the better monocular VEP response only when using small checks (15') and uncorrected vision. Overlapping latencies are consistent with an earlier hypothesis that monocular and binocular VEPs originate postsynaptically from the binocular neurons in the primary visual cortex. The gain in amplitude achieved by binocular stimulation may depend upon the removal of 'tonic interocular inhibition' and/or on a cortical modulatory mechanism.

Adult↗
PubMed1999

Phytoavailability and extractability of copper and zinc in calcareous soil amended with composted urban wastes.

A greenhouse experiment was conducted under simulated field conditions using large-capacity plastic pots, filled each one with 25 kg of air-dried calcareous soil. Besides the control, four treatments were prepared by applying separately two rates (20 and 80 Mg ha-1) of municipal solid waste (MSW) compost, and co-composted municipal solid waste and sewage sludge (MSW-SS). Lettuce was planted and harvested 2.5 months later. The application of composted urban wastes tended to increase Cu concentration in lettuce with respect to the control, but it was only significant when the higher rate of MSW compost was applied. The control showed values of Zn concentration in plant within a deficient range. In general, composted urban wastes treatments had increased Zn concentration values, which were within the sufficiency range. Both treatments with MSW compost increased Cu and Zn uptake in comparison with MSW-SS co-compost treatments. At the postharvest, all composted urban wastes treatments increased significantly DTPA-extractable Cu content in soil with respect to the control; it was also significant the increase in AAAc-EDTA-extractable Cu in soil produced by the addition of the higher rate of MSW compost. The application of composted urban wastes increased significantly DTPA-extractable and AAAc-EDTA-extractable Zn contents in soil versus the control, except for the lower rate of MSW-SS co-compost. The values of DTPA-extractable/total ratio for Cu and Zn were under 10%, except for the treatment applying the higher rate of MSW compost which promoted higher values. The values of AAAc-EDTA-extractable/total ratio for Cu were above 10% in all treatments including the control. This tendency was also observed in AAAc-EDTA-extractable/total ratio for Zn when applying both rates of MSW compost or the higher rate of MSW-SS co-compost.

Biodegradation, Environmental↗
PubMed1998

Scalp topography and source analysis of interictal spontaneous spikes and evoked spikes by digital stimulation in benign rolandic epilepsy.

OBJECTIVES: We report the analysis of scalp topography and dipole modeling of the rolandic spikes in 6 patients suffering of benign rolandic epilepsy of childhood with extremely high amplitude SEP by tapping stimulation of the finger of the hand. METHODS: EEG and BESA analysis were performed for both rolandic spontaneous interictal spikes and high amplitude scalp activity evoked by tapping and electrical stimulation of the first finger of the right hand. RESULTS: The evoked responses showed a morphology characterized by a rapid phase (spike) followed by a slow phase (slow wave). The spike presented an early small positive component followed by a main negative component. Similar morphology, dipole configuration and source localization were observed for both rolandic spikes and evoked high amplitude scalp responses. Dipole localization showed an overlap of spatial coordinates between rolandic and evoked spikes. CONCLUSIONS: These findings suggest that the extremely high amplitude SEPs could be evoked spikes which probably had the same cortical generators of the spontaneous rolandic spikes.

Brain Mapping↗
PubMed1998

Fractions of calcium in the plant-soil system affected by the application of olive oil wastewater.

A pot experiment using calcareous soil was conducted in a growth chamber to examine the effects of olive oil wastewater applications on Ca fractions in the plant and on exchangeable Ca in soil after plant growth. The experimental treatments consisted of two rates of olive oil wastewater, two mineral fertilizer treatments including K, which supplied K in amounts equivalent to the K supplied by the olive oil wastewater treatments, a mineral fertilizer without K treatment (F), and a control. The pots were sown with ryegrass which was harvested 3 times at monthly intervals. The high rate of olive oil wastewater resulted in a prolonged increases in dry matter production. It also resulted in a reduction in the concentrations of soluble Ca, bound Ca, inorganic insoluble Ca and organic insoluble Ca in the plant shoots relative to the control and the F treatment. The low rate of olive oil wastewater produced similar but less marked effects, with decreases being observed in the soluble Ca and bound Ca fractions. After 3 months of plant growth, soil exchangeable Ca was higher in the control and F treatment soils than in the soils receiving olive oil wastewater or K fertilizer. At this time, there were no significant differences in exchangeable Ca between the soils receiving olive oil wastewater and those treated with K fertilizer.

Calcium↗
PubMed1998

Effects of voluntary contraction on tibial nerve somatosensory evoked potentials: gating of specific cortical responses.

We evaluated vertex-parietal P37, N50, and contralateral N37 somatosensory evoked potentials (SEPs) to posterior tibial nerve stimulation during weak (20 to 30%) and strong (80 to 90%) ipsilateral gastrocnemius-soleus contraction. The results were compared with data obtained during full relaxation. P37 and N50 were attenuated significantly during weak contraction and then abolished during strong contraction, whereas the contralateral N37 was not. The N37 potential spreads over the vertex and over the ipsilateral parietal region during strong contraction. The Cz'-F3 montage was not appropriate for detecting these SEP patterns. These findings suggest that thalamic or cortical gating mechanisms affect specific cortical responses. P37 and N50 could reflect the arrival of the afferent volley into the motor areas from thalamic and cortical (subareas 1 and 2 of S1) projections. N37 could be generated in subarea 3b. Differential analysis of N37 and P37 is required in clinical practice, mainly in those conditions that involve the motor system and in those conditions in which tonic muscular activity is increased.

Adult↗