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Biomedical subjects

C Franzini

Publications and source records attributed to C Franzini.

At least 73 records · Page 4Linked to original sources
PubMed1989

Muscle blood flow changes during sleep as a function of fibre type composition.

In rabbits blood flow was measured in 19 muscles with the radioactive microsphere technique. Fibre type composition (SO, slow-twitch oxidative; FOG, fast-twitch oxidative-glycolytic; FG, fast-twitch glycolytic) was determined histochemically for the same muscles. While no significant changes occur in the transition from quiet wakefulness (QW) to synchronized sleep (SS), in desynchronized sleep (DS) blood flow decreases in SO and increases in FOG and FG fibres. These changes may be related to the changes in motor activity characteristic of DS: muscle atonia and twitches, respectively.

Animals↗
PubMed1988

Evaluation of determination of uric acid in serum and whole blood with the Reflotron.

The performance of the Reflotron system (Boehringer Mannheim) for the determination of urate in whole blood and serum was evaluated. Within-run and day-to-day imprecision of the system were comparable with those for a solution-chemistry enzymatic method (overall CVs in the range 2.2-2.5%). Results for 100 individual specimens with urate concentrations ranging from 16 to 134 mg/L agreed well with the comparison method, both for serum and whole blood. We saw no significant interference from lipemia or hemoglobin. Bilirubin interfered at concentrations greater than 100 mg/L. Hematocrit variation between 25% and 55% did not affect results for whole blood; variation of the applied sample volume from 28 microL to 35 microL (stated sample volume requirement: 30 microL) did not significantly influence the measured value. We consider results produced by the system to be of the same analytical quality as those obtained by the more conventional solution-chemistry methods that are currently available.

Bilirubin↗
PubMed1988

Blood haemoglobin determination as haemiglobin isothiocyanate.

A method for the determination of blood haemoglobin, as haemiglobin isothiocyanate was developed and evaluated. Appropriate concentrations of the reagents were chosen to minimize the risk of turbidity from plasma proteins. The stability constant of the isothiocyanate derivative was measured, then used to select a KSCN concentration high enough to bring about complete transformation. The method compared fairly well with the standard HiCN method, and with automatic haemoglobin measurements. The proposed procedure has no particular analytical advantages over the standard HiCN method, the haemiglobin azide method, or the alkaline haematin method; but it uses low-toxicity, non-hazardous chemicals.

Hemoglobins↗
PubMed1988

Determination of serum cholesterol on the Reflotron (BBR) dry chemistry analyser. Assessment of accuracy.

This investigation is aimed at assessing the accuracy of S-cholesterol determination by means of the Reflotron, an analytical system based upon the dry chemistry approach. Two sets of sera, one of them including specimens with elevated concentrations of urea, creatinine, glucose, urate or bilirubin, were assayed in parallel with the Refloton system, with a class-A "reference" method (including alkaline hydrolysis and extraction) and with a routine liquid chemistry enzymatic method. Results for both sets of sera indicated good agreement of the tested system with the routine method, whilst a small proportional negative bias was observed in comparison with the "reference" method. The use of the reference method as a basis for comparison allows more conclusive statements about accuracy to be made.

Autoanalysis↗
PubMed1987

Brain circulation during sleep and its relation to extracerebral hemodynamics.

Regional cerebral blood flow (rCBF) was measured in rabbits during the sleep-waking cycle, using radioactive microspheres. rCBF does not change significantly in the transition from wakefulness (W) to synchronized sleep (SS), while it significantly increases during desynchronized sleep (DS). No correlation was found between CBF changes and changes in cardiac output or regional blood flows in the transition from SS to DS. This suggests that the CBF increase in DS is not relevantly affected by changes in extracerebral hemodynamic factors.

Animals↗
PubMed1987

Stability constants of haemoglobin cyanide and azide measured by two-wavelength spectrophotometric method.

A two-wavelength spectrophotometric procedure for the simultaneous determination of haemoglobin and haemoglobin cyanide (HiCN) (or of haemoglobin and haemoglobin azide (HiN3)) concentrations in mixtures has been developed and applied to the determination of the stability constants of HiCN and HiN3. The analytically reliable procedure allowed stability constants to be estimated with about 10% (relative standard deviation, coefficient of variation) uncertainty. Values of 1.9 X 10(6) and 2.0 X 10(5) 1 X mol-1 were obtained for HiCN and HiN3, respectively. These results are discussed in relation to the optimal composition of the reagents for blood haemoglobin assay by the two methods.

Azides↗
PubMed1987

Caffeine-splitting of bilirubin/albumin complex: its relevance to the spectrophotometry of bilirubin in serum.

By means of gel-filtration of bilirubin/albumin mixtures, it is shown that unconjugated bilirubin remains completely linked to albumin (both human and bovine) in tetraborate buffer (pH 9.3), protein-free bilirubin appearing only when the bilirubin/albumin molar ratio exceeds two. On the other hand, bilirubin is completely set free from its protein link in the caffeine reagent. Additional chromatographic and spectrophotometric evidence is reported indicating the formation of a low-affinity complex between bilirubin and caffeine. These data explain why the spectrophotometric properties of bilirubin/albumin mixtures are matrix-dependent if measured in the tetraborate buffer but are no longer so when measured in the caffeine reagent. The relevance of these findings to the spectrophotometric "direct" assay of bilirubin in serum is discussed with reference to the occurrence of "delta-bilirubin" in pathological sera: this tightly protein-bound bilirubin fraction does not split in the presence of caffeine.

Albumins↗
PubMed1986

Influence of brown adipose tissue on deep cervical temperature during sleep in the young rabbit.

In young rabbits the slope of the temperature in the deep cervical region close to brown adipose tissue increased during desynchronized sleep at low ambient temperature. No increase occurred at neutral ambient temperature. In control rabbits (after disappearance of brown adipose tissue), the slope of deep cervical temperature did not increase during desynchronized sleep at low or neutral ambient temperatures.

Adipose Tissue, Brown↗
PubMed1986

Cloning and sequencing of the pertussis toxin genes: operon structure and gene duplication.

Pertussis toxin, a protein composed of five different subunits (S1, S2, S3, S4, and S5), is the major virulence factor of Bordetella pertussis. We have cloned and sequenced a DNA fragment of 4.7 kilobases that contains the genes coding for the five subunits. The genes are clustered within 3.2 kilobases in the following order: S1, S2, S4, S5, and S3. A sequence closely resembling Escherichia coli promoters is found only before the S1 gene, and a possible termination signal is present at the end of the S3 gene, which suggests that the pertussis toxin genes are organized in a single operon. A possible Shine-Dalgarno sequence is present before the S1 gene but not before the other four genes that 8-12 nucleotides upstream from the ATG codon show a new consensus sequence, 5'TCC(T)GG3', possibly involved in the regulation of translation. We have also found sequence homology between the S2 and S3 genes and their protein products indicating that gene duplication played a major role in the evolution of pertussis toxin.

Amino Acid Sequence↗
PubMed1986

Regional spinal cord blood flow during sleep-waking cycle in rabbit.

Spinal cord blood flow (SCBF) was measured in rabbits during the sleep-waking cycle with the use of radioactive microspheres. The values obtained during wakefulness (W), synchronized sleep (SS), and desynchronized sleep (DS) were 18.1 +/- 2.1, 18.9 +/- 2.6, and 34.4 +/- 2.5 (SE) ml X min-1 X 100 g-1, respectively. Differences relative to SS were not significant in W and were significant at the 0.05 level in DS (modified t test and Bonferroni's method). The increase in blood flow during DS was due to a decrease in vascular resistance. The mechanism of the vasodilation during DS has yet to be identified.

Animals↗
PubMed1985

Liquid control materials for haemoglobins A2 and F: a one-year interlaboratory evaluation.

Stabilised haemolysates, to be stored at -20 degrees C in the liquid state, have been evaluated in an interlaboratory trial: haemoglobin A2 and haemoglobin F levels were stable for at least 1 year. Since the materials can be very easily prepared in each laboratory, they appear to meet the requirements for use in internal quality-control schemes, for the assay of both haemoglobin fractions.

Drug Stability↗
PubMed1985

Preparation and control of ethylene glycol-stabilized haemolysates for glycated haemoglobin assay.

The preparation and evaluation of ethylene glycol-stabilized haemolysates for use as control material for the assay of glycated haemoglobins is described. These haemolysates were prepared from normal and diabetic blood samples by following the procedure normally used to purify human haemoglobin, with the addition of dialysis to remove glucose from the labile fractions, and dilution with ethylene glycol. All the haemoglobin fractions were converted into the carbon monoxide form to increase their stability and were stored under different conditions. During a 10 month period of storage at -20 degrees C no significant change in the glycated haemoglobins level was observed.

Blood Glucose↗
PubMed1984

Nucleosome "phasing" and cruciform structures in circular supercoiled pBR322 DNA.

Cruciform structures have been detected in pBR322 supercoiled DNA, both in its naked state and when complexed with histone octamer, using S1 endonuclease cleavage and EcoRI restriction. An inspection of the DNA sequence shows that the S1-hypersensitive sites are very near to AT-rich regions of pBR322 genome. A nucleosome "phasing" in these regions, as found on AT-rich regions of SV40 DNA (15), has been shown by restriction enzymes analysis. On the basis of these results it can be proposed that cruciform structures protrude on the nucleosome surface. This model explains the reason why these structures, which need high superhelical density, can exist in supercoiled DNA partially relaxed by nucleosome formation.

Base Sequence↗
PubMed1983

Ethylene glycol-stabilized haemolysates as control material in haemoglobinometry.

Human blood haemolysates containing ethylene glycol (final volume fraction 0.35) were prepared and stored at -20 degrees C (in the liquid state) up to 372 days. During the whole period, the total haemoglobin concentration (assayed in the material by means of the reference HiCN method) was found to be stable; spectral analysis also failed in detecting any deterioration, Hi formation being low. Good stability was also recorded on storage at 2-4 degrees C for 15 days, but only for 1-2 days at room temperature. The stabilised haemolysate is suggested as a material for long-term control of accuracy in hemoglobinometry.

Ethylene Glycol↗