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Biomedical subjects

M Manca

Publications and source records attributed to M Manca.

At least 19 recordsLinked to original sources
PubMed1991

[Discordance between clinical and immunological aspects in a case of chronic B-type lymphoproliferative syndrome].

Chronic lymphoproliferative disorders are extremely heterogeneous from a clinical, morphological and immunological point of view. The paper reports the case of a woman with chronic prolymphocytic leukemia. The neoplastic clone revealed the typical immunological features of pre-B lymphocytes, which are at an earlier stage of differentiation in respect to prolymphocytes. After polychemotherapy (CEOP) the phenotype of the neoplastic cells shifted to an immunological pattern typical of B lymphocytes.

Aged↗
PubMed1986

Detection of electrophoretically silent mutations by immobilized pH gradients.

The detection of neutral amino acid mutants, by isoelectric focusing in immobilized pH gradients (IPGs), is exemplified by the separation of hemoglobin (Hb) Beirut (126 beta Val----Ala) from Hb A in a shallow pH 7.2-7.6 IPG gradient with 2% Ampholine pH 6-8. The mechanism of these separations appears to involve minute alterations in the pK values of ionizable groups bordering the mutation site, which are in turn reflected in tiny alterations in the net surface charge, delta pI. The delta pI values are of the order of 0.01 to 0.001 pH units, outside the resolving limits of conventional isoelectric focusing, and correspond to changes of the order of 0.1-0.01 unit charge (a proton or an electron).

Amino Acids↗
PubMed1986

Antenatal diagnosis of beta-thalassemia by isoelectric focusing in immobilized ph gradients.

A new method for antenatal diagnosis of thalassemias is reported based on the analysis of the major Hb components of fetal cord blood, sampled at week 18 of pregnancy under ultrasonic guidance, by isoelectric focusing in immobilized pH gradients (IPG). In an IPG gel encompassing a pH 6.7-7.6 span, HbA and HbFac are separated by a distance nine times greater than in a conventional carrier ampholyte pH 6-8 gel and three times greater than in an ampholine gel with separators (an equimolar mixture of beta-alanine and 6-amino caproic acid). Band evenness (in terms of uniform protein concentration within a zone) and straightness (in terms of parallel alignment of the bands to the electrodes), because of insensitivity of IPG gels to salt distortions, allows for accurate and reproducible quantitation of HbF, -A, and -Fac levels. The possibility of greatly overloading IPG matrices in total Hbs increases the sensitivity of the technique to the detection of only 0.5% HbA in the total Hb mixture, the lower limit of conventional IEF being only 2.5% HbA. Of 15 fetuses from couples at risk analyzed in the region of Ozieri, three were found to be homozygous beta-thalassemic, eight heterozygous, and four normal with no false-positives or -negatives.

Female↗
PubMed1984

[The effect of fatigue on the biopotential of muscle fiber cells].

Muscular fatigue is a biological situation which is very difficult to quantify. The Authors studied through a computer analysis the power spectrum of electromyogram, recorded from abductor digiti minimi muscle during maximal and minimal contraction effort before and after fatigue and after muscle prolonged relaxation in 8 normal subjects. No significant spectrum differences were found between maximal and minimal effort in each trial, and between the spectra obtained before fatigue and after muscle prolonged relaxation. On the contrary significant differences were found between the spectra obtained after fatigue and the other conditions. The power spectrum analysis appears, also, to be a reliable neurophysiological parameter for the study of biological aspects of muscular fatigue.

Adult↗
PubMed1984

[The origin of the electroretinogram induced by structured stimuli in man].

The Authors studied the checkerboard pattern electroretinogram (PERG) behaviour in normal subjects and in patients suffering from traumatic lesion of optic nerve, demyelinating optic neuritis, axonal optic neuritis, retinal vascular disorders and retinitis pigmentosa in order to verify the PERG origin. According to our data the PERG appears to originate from ganglion cells since the signal diminished or disappeared in axonal lesion of optic nerve, as a result of retrograde ganglion cell degeneration. Furthermore, the demyelinating lesions of optic nerve were not able to modify the PERG wave. In patients suffering from retinal receptor disturbances the flash electroretinogram (FERG), which is probably an expression of receptor activity, was greatly impaired, whereas PERGs were either normal or less impaired than FERGs. These data demonstrate the different origin of PERG and FERG.

Electrophysiology↗
PubMed1984

[The effect of thoracic pressoreceptors on heart rate in man].

Sinus arrhythmia (SA) is a physiological event related to the respiratory activity. The aim of this study was to find a relation between SA and different deep breathings. A transductor monitored the chest respiratory movements and a cardiotachometer calculated and plotted the instantaneous heart rate, synchronously during different breathing efforts. In 10 normal subjects a good linear correlation was found between the breathing depth and SA quantifying the relation between the chest receptor activity and SA also with limited chest expansion.

Adult↗
PubMed1984

[The conduction of optic nerve fibers using different visual patterns].

The Authors have studied the behaviour of checkerboard pattern visual evoked potential (VEP) latencies by using different spatial frequency stimuli and different stimulating visual fields in order to demonstrate whether spatial frequency might constitute a parameter capable of exciting different retinal regions like different stimulus fields. According to the recent literature low spatial frequency stimuli generate VEP with latencies which are significantly shorter than high spatial frequency stimuli, making this method more reliable for the differentiation of macular and peripheral retinal fields.

Adult↗
PubMed1984

Determination of glycosylated haemoglobin by isoelectric focusing in non-linear pH gradients.

A new isoelectric focusing technique for the separation and quantitation of glycosylated haemoglobin (HbA1c) is described. By using an equimolar mixture of two separators (0.2 M beta-alanine + 0.2 M 6-aminocaproic acid) a 2-pH unit Ampholine range (pH 6-8) is transformed in a shallow, 0.6-pH unit span (pH 6.7-7.3). This brings about an increment of resolution between HbA and HbA1c by a factor of about three, thus allowing proper densitometric evaluation of the trichloroacetic acid-fixed MetHb bands by conventional gel scanners. Excellent agreement is found among microchromatography, isoelectric focusing followed by densitometry in situ, and isoelectric focusing followed by band excision, elution and spectrophotometric determination. The present method also allows full resolution between HbA1c and fetal haemoglobins (F and Fac bands).

Adult↗
PubMed1984

Pattern electroretinogram in multiple sclerosis.

The pattern electroretinogram obtained in patients affected by multiple sclerosis were compared with those in a normal population. The pattern electroretinogram amplitude in multiple sclerosis optic neuritis frequently appeared normal, but pattern electroretinogram amplitude abnormalities were found in patients suffering from recurrent multiple sclerosis optic neuritis. Pattern electroretinogram examination appears a useful method in the differential diagnosis between axonal and demyelinating optic nerve impairment.

Adult↗
PubMed1983

Static vestibulospinal influences in relation to different body tilts in man.

In this study, H-reflex testing was used to identify possible static vestibular influences on soleus alpha motoneuron excitability in man in relation to different body tilts. Ten normal adult volunteers and one labyrinthine-defective patient were tested in an experimental situation designed to minimize all afferent inputs except the vestibular ones. Each subject was fixed to a rigid platform inclinable from the horizontal (0 degree) to the vertical (90 degrees) position and vice versa. On each subject, 10 consecutive H reflexes were recorded for each of the following positions: 0 degree, 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees, 90 degrees and 90 degrees, 75 degrees, 60 degrees, 45 degrees, 30 degrees, 15 degrees, 0 degree. In all normal subjects, we observed a significant increase in amplitude of the H reflex as the body was tilted from horizontal to vertical, and a significant decrease when the body was returned to the original position. These progressive changes in spinal motoneuron excitability were linearly related to the tilt angles. By contrast, no significant change in H-reflex amplitude was observed in the labyrinthine-defective patient. These results would seem to indicate that the vestibular system exerts some influences on antigravity muscles in static tilts and that these influences are behaviorally adequate to provide for the postural stability.

Adult↗
PubMed1983

The frequency of multiple sclerosis in Mediterranean Europe. An incidence and prevalence study in Barbagia, Sardinia, insular Italy.

Recent investigations on multiple sclerosis (MS) distribution in Italy, based on relatively small population groups, contradict the current thesis, derived from studies undertaken in populations exceeding 300,000, of a lower spreading of the disease in Mediterranean Europe. Intensive surveys on small populations strengthen the suggestion that Italy is a high-risk area, although MS studies based on prevalence rather than incidence could also be biased by geographic variables making prevalence unsuitable for comparing MS prevalence rates found in different years and/or zones. We report a further epidemiologic study in Barbagia, Sardinia, insular Italy, undertaken both to establish the MS incidence in the last 20 years, and to estimate a new prevalence rate. Based on 31 probable incident cases, the mean incidence per year for the years 1961-1980 was 2.9 per 100,000 (3.2 if age- and sex-standardized to the Italian population). On October 24, 1981, the prevalence per 100,000 was 65.3 (77.9 if standardized to the Italian population). These results confirm that in Barbagia, MS occurs more frequently than expected in a Mediterranean area, and give further support to the idea that MS frequency in Italy is similar to that established for most central and northern European countries.

Adolescent↗
PubMed1982

Neonatal screening of beta-thalassemias by thin layer isoelectric focusing.

As an alternative to the recently proposed screening for beta-thalassemias by isoelectric focusing (IEF) of denatured globin chains in urea-detergent gels [6], IEF of intact hemoglobins, obtained from umbilical cord blood in neonatal units, is reported here. For maximum separation, IEF should be performed in nonlinear pH gradients, in gels containing 0.2 M beta-alanine and 0.2 M 6-amino caproic acid, which flatten the pH gradient around pH 7, thus increasing the resolution between HbA and HbFac. The method can unambiguously detect homozygous and heterozygous beta-thalassemic conditions. A bimodal distribution of HbA at birth has been found: In heterozygous patients, HbA values of 9.02% (range 6.8-9.98%) have been found while in normal newborns HbA levels of 20.34% (range 11.02-30.6%) have been demonstrated.

Fetal Blood↗
PubMed1982

Uremic neuropathy: correlations between electroneurographic parameters and serum levels of parathyroid hormone and aluminum.

An electrophysiological investigation on 29 dialysis patients was performed with the aim of verifying whether serum parathyroid hormone (PTH) and aluminum (Al) levels may play a role in the pathogenesis of uremic neuropathy. All patients except 1 showed electrophysiological abnormalities. Both PTH and Al levels were found to be significantly correlated with the time on dialysis. On the contrary, the values of each single electroneurographic parameter did not show any correlation with the duration of dialysis, PTH levels and Al levels. The authors conclude that PTH and Al does not seem to play a role in the etiology of uremic neuropathy.

Adult↗
PubMed1981

The diagnostic value of H-index in S1 root compression.

The H-index was studied in 42 healthy subjects and in 20 patients showing unilateral S1 root compression. When compared to the normal subjects, all patients showed a decreased H-index, or an increased difference in H-index between the sides or both. These results indicate that both parameters are valuable in the diagnosis of S1 root impairment due to intervertebral disc protrusion.

Adult↗