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Biomedical subjects

G Ricco

Publications and source records attributed to G Ricco.

At least 19 recordsLinked to original sources
PubMed2002

Functional studies on nine different haemoglobins with high oxygen affinity.

Nine carriers of beta-abnormal haemoglobins with increased oxygen affinity (Hb X) were examined. Their oxygen dissociation curves from whole blood were more or less left-shifted, with six of nine also characterized by biphasism. This refers to an 'inflection point' usually positioned at about 50-60% of Hb O(2) saturation, commonly believed to be a limit between oxygenation of the normal and abnormal components. In effect, the inflection does not always correspond to the Hb X level, which sometimes is much lower than 50% of the total Hb. Moreover, the upper half segment of the dissociation curve could not only be an expression of Hb A oxygenation, since it is always left-shifted. However, a high Hb A level is commonly believed to be the main compensatory factor of these subjects, but many indications suggest that often they have at least three, and not only two, main haemoglobin species: Hb A, Hb X plus hybrids of the type alpha(2)beta(A)beta(X). These would oxygenate after Hb X, but before Hb A. Finally, the interaction of 2,3-diphosphoglycerate with Hb X and/or hybrid tetramers must be altered, and the releasing of oxygen from both is more or less reduced. Unfortunately, it is difficult to demonstrate the presence of hybrids directly, i.e. with amino acid analysis of the abnormal beta-globin.

Chromatography, High Pressure Liquid↗
PubMed2000

Photoproduction of straight phi(1020) mesons on the proton at large momentum transfer

The cross section for straight phi meson photoproduction on the proton has been measured for the first time up to a four-momentum transfer -t = 4 GeV2, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. At low four-momentum transfer, the differential cross section is well described by Pomeron exchange. At large four-momentum transfer, above -t = 1.8 GeV2, the data support a model where the Pomeron is resolved into its simplest component, two gluons, which may couple to any quark in the proton and in the straight phi.

Journal Article↗
PubMed1998

[Functional analysis of diluted solutions of human hemoglobin by using Oximeter-3000 WTW equipped with Trioxmatic-300 electrode].

The oxygen carrying capacity of dilute solutions of hemoglobin from normal human adults was examined, by using the above indicated Oximeter. The results show that, if the pO2s are compared with those drawn from the Oximeter-539 WTW (a simpler instrument) carrying the same oxygen electrode, there is a good correspondence between the data drawn from both the instruments. The advantage of the former is that pO2s are measure in mBr, whereas the latter measures the oxygen of the aqueous solutions in mg/l; then mg must be converted into Torr pO2. Since both instruments are usually employed in the oxygen measurement of waste waters of earth, another conclusion is that their sensitivity also allows the use in the bio-medical (and zoological) field. In fact, the data obtained agree with those of recent literature on the subject, which are mainly drawn from automated and sophisticated apparatuses specifically built at this purpose.

Adult↗
PubMed1998

Hemoglobin Agenogi [beta 90 (F6) Glu-->Lys] found in Piedmont. Case report.

An electrophoretically slow-moving hemoglobin, with abnormal beta chains, has been found in a young woman and in three members of her family. This variant amounted to 41% of the total Hb, and did not cause important clinical manifestations, although characterized by decreased oxygen affinity. Structural and aminoacid analyses revealed the mutation of Hb-Agenogi: 90 (F6) Glu-->Lys, a rare variant so far detected in unrelated racial and ethnic groups. This is the first affected family of ascertained Piedmontese ancestry.

Adult↗
PubMed1997

A new fast-moving variant causing erythrocytosis and mild hemolysis: Hb Gàmbara [beta 82(EF6)Lys-->Glu].

Hb Gàmbara is a new hemoglobin variant with abnormal beta chains that has been found in three out of four members of a family of Lombardy origin (Gàmbara, Brescia, Northern Italy). The affected subjects led a normal life, but they had modest erythrocytosis and mild (compensated) hemolysis with slight splenomegaly. Their abnormal hemoglobin was about 52% of the total hemoglobin, and was shown to be stable by the isopropanol test. Whole blood P50 of the proband was 19.3 Torr, Bohr effect was decreased (-0.25), as well as the molar ratio between the 2,3-diphosphoglycerate level and total hemoglobin of erythrocytes (0.68). The purified abnormal hemoglobin was characterized by an altered oxygen affinity, low n-factor, chloride, and 2,3-diphosphoglycerate effects. The Bohr effect was about 40% of the normal control. The abnormal hemoglobin moved faster than Hb A at alkaline electrophoresis, and split into two fractions, probably due to the formation of hybrid tetramers (alpha 2 beta A beta X). The reversed phase high performance liquid chromatogram from the tryptic digest of the aminoethylated abnormal beta chain subunits indicated the presence of an extra peptide, beta T-9, 10, replacing the individual peptides beta T-9 and beta T-10. Finally, the proband's DNA, drawn from a suitable segment of the beta structural gene (exon 2), revealed a nucleotide sequence carrying the heterozygous mutation AAG-->GAG at codon 82. This led to a Lys-->Glu substitution at position 82(EF6) of the beta chain.

Electrophoresis↗
PubMed1997

Use of the Oximeter-539 WTW, equipped with a sensor Trioxmatic-300, for the functional analysis of dilute solutions of human Hb-A.

Dissociation curves for oxygen of dilute samples of human adult Hb-A were evaluated on this occasion, by using the Oximeter-539 WTW with its sensor, and a suitable spectrophotometer. At this purpose, Hb samples were desaturated in oxygen upon given experimental conditions, by bubbling pure nitrogen in them, and their re-oxigenation in air was followed, step by step, by multiple oximetries. In addition, all the spectrophotometric measurements of the saturation of Hb-O2%, corresponding to each individual oximetry, were carried out parallely but separately. Dilution of Hb-A was maintained at 0.1 mM in heme. The p50 at pH 7.3 was 4.435 +/- 0.299 Torr, with the n-value of 2.7 +/- 0.2; Bohr effect was -0.55 +/- 0.08, within a pH range between 6.8, 7.3 and 7.8, whereas chloride and DPG effects at pH 7.3 (the most useful value) were 0.42 +/- 0.44 and 0.453 +/- 0.0187 respectively. In conclusion, these results are similar to those obtained with automated procedures, upon comparable experimental conditions, but do not require expensive and sophisticated instruments. Such a technique could be very useful in the hemoglobinopathies, which are common in Italy, and it could be easily adapted to perform comparative studies on animal hemoglobins not far from human species.

Adult↗
PubMed1997

Studies on the oxygen transport in the clinical association between Hb-S and Hb-C.

The whole blood oxygen affinity of a Negro carrier of SC disease was found to be characterized by some right-shifted p50 and clearly increased Bohr effect, whereas the isolated and purified Hb-S and Hb-C exhibited slight deficiencies mainly of the Bohr effect. The right-shifted p50 from whole blood can be easily explained by the mild anemia with a parallel increase of 2,3-diphosphoglycerate (DPG), whereas the functional discrepancies between whole blood function and that of the purified Hb-S and C could be due, at least in part, to the presence in vivo of consistent amounts of hybrid Hb tetramers of the type alpha alpha beta S beta C. Unfortunately, the mechanism promoting the formation (or dissolution) of hybrids are fundamentally unknown; so, either their presence and functional properties are very difficult to be explored.

Adult↗
PubMed1994

The updated BESGE spectrometer for pure beta activities in environmental matrices.

This work describes an updated version of a beta spectrometer that measures pure beta emitter activities. The detection system consists of a plastic scintillator surrounded in a 4 pi geometry by large anticoincidence NaI(Tl) scintillators. A thin silicon detector, inserted between the plastic and the sample, helps to reduce the gamma background. A Monte Carlo code, used to calculate the quite complex spectrometer response function to any isotope, is also described.

Beta Particles↗
PubMed1992

A beta spectrometer for monitoring environmental matrices.

In environmental matrices, pure beta emitters are often present with other beta-gamma emitters. This work describes a beta spectrometer that allows measurement of pure beta-emitter activities of about 10(-2) Bq. The detection system consists of a plastic scintillator surrounded in a 4 pi geometry by large anticoincidence NaI(Tl) scintillators. Solid, liquid, and gaseous samples can be analyzed, and no chemical separation is necessary. The system is particularly useful for 90Sr measurement.

Beta Particles↗
PubMed1992

Functional properties of dilute Hb solutions studied without tonometric techniques.

The authors found that, by continuously bubbling pure nitrogen within a dilute Hb solution, the latter releases its oxygen with an intensity which is quite proportional to the duration of bubbling. Such a procedure can be employed instead of the common tonometric technique, to measure functional properties of Hb. In fact, not only dissociation curves can be obtained, but also a correct evaluation of the affinity changes upon pH variations (Bohr effect). The results obtained by this technique are not far from those recently reported by using tonometry, although the method is less precise and still not suitable for routine purposes. Nevertheless, it can be substantially improved.

Hemoglobinometry↗
PubMed1992

Functional behaviour of dilute solutions of Hb-Kempsey: beta 99 (G-1) Asp--Asn.

The authors report that a diluted solution of Hb-Kempsey, beta 99 (G-1) Asp-Asn, can be chromatographically separated from the coexistent Hb-A and functionally examined if progressively depleted in O2 by bubbling pure nitrogen in the solution. Next, at fixed times, the O2 saturations of Hb are compared with the pO2s measured. Hb-Kempsey has a p50 of 1 torr, with an n-value of 1 and a Bohr effect of -0.2. Normal Hb-A of the same patient, examined with identical methods, presents: p50 = 4.5 torr; n = 2.7; Bohr effect = -0.412. Therefore, Hb-Kempsey is strongly hyperaffinic, does not display any heme-heme interaction, and has a half-normal Bohr effect.

Chromatography, Gel↗
PubMed1991

[The acute treatment of supraventricular tachycardia with endovenous amiodarone].

In the present study we evaluated 35 patients of both sexes, aged 21-84, with newly occurring supraventricular tachyarrhythmias, 19 atrial fibrillation (AF), 6 atrial flutter (FL) and 10 paroxysmal supraventricular tachycardias (PSVT). They were treated with a single amiodarone infusion up to two hours after the restoration of a stable sinus rhythm or to a maximus dose of 2,400 mg (in 24 hours). Plasma amiodarone concentration and QTc were measured at the restoration of sinus rhythm and twelve hours after the amiodarone withdrawal. Amiodarone infusion restored a stable sinus rhythm in all 10 patients of the PSVT group (100%), in 5 of the FL group (83%) and in 16 of the AF group (84%). The average dose needed to stop PSVT was lesser than for AF and FL (M + SE: 473.3 +/- 36.88 vs 1842.1 + 259.6 vs 1548.8 +/- 345.5 mg; p less than 0.001). The average plasma amiodarone concentration at the restoration of sinus rhythm was 2450.4 +/- 175.9 SE ng/ml in all the tachyarrhythmias as a whole without any statistically significant difference among PSVT, FL and AF. Moreover no correlation exists between plasma amiodarone concentrations and the amount of amiodarone infused. QTc showed a statistically significant transient lengthening at the restoration of sinus rhythm, but not twelve hours after amiodarone withdrawal. In conclusion, a single dose of amiodarone is effective and safe in all newly occurring supraventricular tachyarrhythmias, without any important side effect and with a high therapeutic index in pharmacologic cardioversion as alternative treatment to cardioversion.

Adult↗
PubMed1991

Functional properties of Hb-J Calabria, beta 64 (E8) Gly-Asp.

A young male from Apulia region (Southern Italy), heterozygous carrier of Hb-J Calabria (beta 64(E8) Gly-Asp), was described here. He showed mild polycythemia, and his whole blood dissociation curve for oxygen was clearly left-shifted, with a decreased p50. But these characteristics were not only due to the hyperaffinity of the abnormal pigment, accounting for about one third of the total Hb; in fact, also Hb-A, the main pigment present, had relative hyperaffinity. Nevertheless, this subject was completely symptomless, suggesting that the abnormal Hb was almost completely excluded from respiratory exchange and traveled always oxygenated also in the venous-capillary bed. However, the level reached by Hb-A furnished a satisfactory functional compensation against tissue hypoxia.

Adult↗
PubMed1990

Further studies on oxygen loading in blood from anemic patients.

Functional parameters of the whole blood oxygen loading from 66 anemic subjects, compared with those from 66 normal adult of both sexes display the following behaviour: a) Adult males and females differ for p50 values, which are higher in females because of their lower Hb level. This difference is already well known and appears to be statistically significant. b) The same difference is amplified in anemic subjects, where also pH lowering contributes to the right-shift of p50. c) The inverse relationship between p50 and DPG values differs if analysed at the actual pHs, at pH corrected at 7.4, or extrapolated from Bohr effect. In fact, the three relative plots do not parallel, and their most significant intersects drop around 0.8-0.9 value of DPG, and 26-27 torr of p50, i.e. within normal limits.

2,3-Diphosphoglycerate↗