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Biomedical subjects

L Rossini

Publications and source records attributed to L Rossini.

At least 19 recordsLinked to original sources
PubMed2002

Airway management in an infant with congenital centrofacial dysgenesia.

The use of a laryngeal mask airway (LMA) on two occasions, in a 53-day-old and 270-day-old male infant with Tessier N.3 and N.4 facial defects, using sedation and topical anaesthesia is described. The LMA was used to manage the airway and facilitate inhalation induction of anaesthesia as the facial deformities were thought to be too extensive for the safe use of a facemask. The LMA is an alternative to a facemask and secures the airway and facilitates the inhalation induction of anaesthesia in paediatric patients with severe facial deformities.

Anesthesia, General↗
PubMed2002

[Topical anesthesia for cataract surgery with phacoemulsification: lidocaine 2% vs ropivacaine 1%. Preliminary results].

BACKGROUND: The safety, tolerability and efficacy of ropivacaine 1% vs lidocaine 2% for phacoemulsification using topical anesthesia during cataract surgery, are compared. METHODS: A prospective, randomized, double-blind study comparing two agents for topical anesthesia is reported. ENVIRONMENT: Operative Unit of Ophthalmology, general Hospital. 1893 consecutively patients were studied (ASA 1-3, 738 males, 1155 females, age 71.8+/-9.7 years, range 35-90 years) undergoing routine phacoemulsification under topical 2% lidocaine (group I) and 1% ropivacaine (group II). The mains outcome measures of the study were: - the total dose of local anesthetic for obtaining a reduction of corneal sensation measured with the Cochet-Bonnet esthesiometer (value>3); - the pain recorded with visual analogic scale and verbal scale at: T1 = the first injection of local anesthetic; T2 = corneal incision; T3 = the end of surgery; T4 = 1h after surgery; T5 = the first postoperative day; - any requirement for additional intraoperative injection anesthesia and systemic sedation when needed; - surgeon assessments of operative conditions and patient cooperation; - patients' subjective level of comfort; - complications. RESULTS: Topical anesthesia using lidocaine 2% was significantly more painful than the ropivacaine 1%. The onset of anesthesia adequate for surgery was similar in all two groups. There were differences between the groups with respect to perioperative analgesia because the VAS was significantly higher in lidocaine group than in ropivacaine group. There were no statistically differences between the two groups at the follow-up. Inadequate anesthesia was seen in 8.05% (74/919 patients) cases of group I vs 0.9% (22/974 patients) of group II. Sedation was needed only in 10 patients and 6 patients of group I and II respectively. The surgeon assessment showed more patient cooperation in the ropivacaine group (83%). Satisfactory comfort (level 1) was reported by 60.4% in the lidocaine group and 86.8% in the ropivacaine group. In both groups there were cases of postoperative epithelial edema (29 patients in group I vs 36 patients in group II) although it decreased after the first postoperative day. No other significant side-effects were observed with the use of either formulations. CONCLUSIONS: Lidocaine 2% and ropivacaine 1% were safe and effective agents in patients having phacoemulsification with IOL implantation. However, ropivacaine provides more good operative conditions than lidocaine for the surgeon and comfortable surgical circumstances for the patient.

Administration, Topical↗
PubMed2001

Patterns and symmetries in leaf development.

The leaf is a coordinated mosaic of developmental domains, which are evident from leaf inception on the flanks of the apical meristem. The subdivision of the meristem into molecularly defined domains is regulated by the interactions of a number of gene products and by receptor kinase-mediated signals. The acquisition of symmetry axes in the emerging leaf is a process coordinated by hormones (such as auxin and cytokinins) and the expression of classes of genes (such as the knox and the ARP, as1/rs2/phan, genes). As with simple leaves, the architecture of compound leaves is defined by spatial/temporal gradients of regulatory gene functions: complexity results from the interplay between leaf differentiation processes and genes maintaining a partial level of indeterminacy in the developing primordium. Boundaries between regions with different molecular 'addresses' are considered, in plants as in Drosophila, as organizing centres for lateral organ development.

Body Patterning↗
PubMed2001

The maize golden2 gene defines a novel class of transcriptional regulators in plants.

In the C4 plant maize, three photosynthetic cell types differentiate: C4 bundle sheath, C4 mesophyll, and C3 mesophyll cells. C3 mesophyll cells represent the ground state, whereas C4 bundle sheath and C4 mesophyll cells are specialized cells that differentiate in response to light-induced positional signals. The Golden2 (G2) gene regulates plastid biogenesis in all photosynthetic cells during the C3 stages of development. However, G2 function is specifically committed to the differentiation of bundle sheath cell chloroplasts in C4 leaf blades. In this article, we report the isolation of G2-like (Glk) genes from maize and rice, providing evidence for a family of Glk genes in plants. The expression profiles of the rice Glk genes suggest that these genes may act redundantly to promote photosynthetic development in this C3 species. In maize, G2 and ZmGlk1 transcripts accumulate primarily in C4 bundle sheath and C4 mesophyll cells, respectively, suggesting a specific role for each gene in C4 differentiation. We show that G2 and ZmGLK1 both can transactivate reporter gene transcription and dimerize in yeast, which supports the idea that these proteins act as transcriptional regulators of cell-type differentiation processes.

Amino Acid Sequence↗
PubMed1998

Spectral analysis of intercycle heart fluctuations in the diethyl-ether-anaesthetized or pithed rat treated with prazosin, dl-propranolol, endothelin-1, alpha-r atriopeptin and ACE-inhibitors.

1. Frequency-domain spectral analysis of stationary ECG R-R intervals was made by fast Fourier transformation (FFT) in conditions of monitored arterial blood pressure and respiratory activity in diethyl-ether-anaesthetized and pithed adult rats. This technique yields a number of parameters which allow quantitative evaluation of the non-random distribution of the mean values obtained in time-domain studies. The frequency-analysis method enables the overall heart rate variability to be broken down into its various constituents, which are differently affected by physiological loading and capable of selective reactivity to pharmacological agents. 2. The low-frequency spectral component obtained by breaking down the total spectral density power, i.e. the appropriate variability signal (band width < 0.15 Hz) and a higher-frequency band corresponding to spontaneous (0.80-1.60 Hz) or artificially imposed (0.75 Hz) respiratory activity were estimated and their integrated areas evaluated as absolute powers or normalized fractional values. 3. The power of the high-frequency spectral component increased in all animal preparations under treatment with prazosin, dl-propranolol, endothelin-1 and the angiotensin converting enzyme (ACE) inhibitors captopril, lisinopril, quinapril and ramipril. The power of the low-frequency band increased under alpha-r atriopeptin and ACE inhibitors in the pithed preparations only, and decreased in the anaesthetized animals. 4. The new power spectrum features and trends detected indicate that these time-independent, model-dependent cardiovascular and respiratory markers are subject to some form of complex peptidergic control. 5. The relative roles of the various factors operating in the genesis of these short-term changes in spectral power in the low- and high-frequency bands cannot be interpreted as indicating a reciprocal push-pull relationship between sympathetic and parasympathetic control. 6. The study findings, however, can be interpreted as providing evidence of a different and to some extent alternative form of integrative cardiovascular control persisting in the pithed rats (i.e. in the 'peripheral', CNS-destroyed preparations). 7. New areas of theoretical and applied research are being developed in the (auto)classification of (iso)receptors and drug analogues through exploration of multiple physiological and pharmacokinetic parameters in the frequency-domain. Furthermore, model-independent frequency-domain methods not requiring stationary data will afford scope for even more significant developments by separating the overlapping dynamic processes from a whole series of correlated effects.

Animals↗
PubMed1998

GOLDEN 2: a novel transcriptional regulator of cellular differentiation in the maize leaf.

The differentiation of distinct cell types within the leaf is essential for normal plant development. We characterized previously a transposon-induced mutant of maize (bundle sheath defective1) that disrupts the differentiation of a single photosynthetic cell type in the leaf. In this study, we show that this mutation is allelic to golden2 (g2), a lesion first reported 70 years ago. We cloned G2 by using Suppressor-mutator as a molecular tag. The gene encodes a 2. 2-kb transcript that is present throughout the wild-type leaf but is most abundant in C4 leaf blade tissue. Gene sequence data showed the existence of a bipartite nuclear localization signal encoded by the first exon, and we determined that G2 reporter gene fusions are targeted to the nucleus in onion epidermal cells. Further sequence analysis indicated the presence of a novel motif within the deduced protein sequence that shares features with TEA DNA binding domains. Therefore, we propose that G2 acts as a novel transcriptional regulator of cellular differentiation in the maize leaf.

Amino Acid Sequence↗
PubMed1997

(ECTO) nucleotidase kinetics observed by 31P-NMR spectroscopy: resolution of signals.

We used 31P-NMR to study the action of the drug ouabain, a digitalis glycoside, on the ecto-nucleotidase catalysed reaction pathway: [formula: see text] Even under conditions where it was impossible to resolve all resonances from the individual species, the rate constants for the individual steps may be evaluated by a chi 2 fit of equations describing the global kinetics to the NMR data. The fitted values of the reaction rate constants show no inhibition of any step in the reaction pathway, confirming previous results. This improved kinetic method can be used to evaluate the effect of different substrates, ions and drugs, both in intact or pathologically altered organs and in tissue subcellular fractions.

Adenosine Triphosphatases↗
PubMed1997

Spectral analysis of intercycle heart fluctuations in Xenopus laevis, conscious or spinalized, treated with calcium channel blockers. Part I.

1. In this study, electrocardiographic second lead tracings were recorded and analyzed online and offline in the conscious and spinalized Xenopus laevis under control conditions and after treatment with at least two effective doses of racemic diltiazem, nifedipine and racemic verapamil hydrochlorides. 2. Heart rates (HR) and intercycle heart rate power spectra (IHRPS) were calculated in the various experimental conditions. 3. Dose-dependent bradycardia was found in most cases, which was associated with dose-related increases in the overall dynamic range of the largest peak of HR variability (increased IHRPS), this being particularly marked at the higher nifedipine dose. The frequency position of the largest peak was unchanged in the spinalized preparation, as well as in the various treatments. 4. These findings may contribute toward a more complete pharmacodynamic definition of calcium channel blockers in their current therapeutic use.

Animals↗
PubMed1997

Spectral analysis of intercycle heart fluctuations in the diethyl-ether-anaesthetized or pithed rat treated with l-hyoscyamine.

1. Within the context of neural regulation of the activity of sinus node pacemaker cells, the study of heart rate variability, as explored in the frequency domain by spectral analysis, was proposed about 15 years ago as a quantitative tool for the evaluation of short-term autonomic cardiovascular control. It has since been postulated that the two main oscillations observed, one at low and the other at high frequency, may respectively be markers of sympathetic vs. vagal efferent cardiac activity, and that the low- and high-frequency signals may reflect a reciprocal or 'push-pull' relationship between sympathetic and parasympathetic control. 2. In our power spectra assessment, ECG R-R intervals were submitted to fast Fourier transformation analysis in order to study the mechanisms underlying the control of heart beats in rats. Data were acquired in conditions of steady arterial blood pressure and cardiac and respiratory activity (spontaneous or artificially stimulated) in diethyl-ether-anaesthetized and pithed rats, as well as in a group of control rats, all in the presence and absence of l-hyoscyamine. 3. With increasing doses of the parasympathetic antagonist, the fractal dimension of the time-series structure remained stable in most cases. The low-frequency spectral component narrowed with increasing drug doses and the high-frequency band underwent either no, or only very slight, changes. 4. In these rodent assays, the low- and high-frequency signals cannot be interpreted as a push-pull relationship between sympathetic and parasympathetic control.

Anesthetics, Inhalation↗
PubMed1995

Molecular analysis and mapping of two genes encoding maize glutathione S-transferases (GST I and GST II).

Maize glutathione S-transferase (GST) isozymes are encoded by a gene family comprising at least five genes, three of which (Gst I, II and III) have recently been isolated and sequenced. The enzymes are active as homo or heterodimers and exhibit intraspecific polymorphism including a "null" variant for the two major isoforms expressed in roots. Northern blot analyses performed on total root RNA from "null" and "plus" genotypes, using Gst I- and Gst II-specific probes, indicated that the Gst I gene controls the expression of the two major GST isoforms expressed in roots. Gst I and Gst II were mapped by RFLP analysis using an F2 population of 149 individuals previously characterized. Gst I was localized on the long arm of chromosome 8, while two putative Gst II loci were mapped to chromosome 8 (70 cM from Gst I) and 10, respectively.

Alleles↗
PubMed1993

A 31P NMR spectroscopy study of Xenopus laevis heart perfused in vitro with creatinol-O-phosphate, phosphocreatine, adenosine triphosphate, fructose diphosphate and ouabain.

Xenopus laevis heart was studied by 31P NMR using a 200 MHz proton spectrometer; hearts were perfused, at pH 7.35 and room temperature, with normal oxygenated or K(+)-enriched Ringer. Solution was later added with creatinol-O-phosphate (COP), phosphocreatine (PCr), adenosine triphosphate (ATP), fructose-1,6-diphosphate (FDP) and ouabain. NMR spectra of the heart show organic phosphomono- and phosphodi-esters, inorganic phosphate, PCr, overlapping alpha-ATP/ADP and gamma-ATP/beta-ADP, and beta-ATP signals. Their chemical shift positions and areas showed no significant changes in the course of 1.5 h perfusions with either solution, except in a few preparations, whether the heart was beating or reversibly arrested. While COP reduced the signals in beating hearts, the same spectra exhibited no consistent, substantial changes under PCr, ATP and FDP 1 to 10 mM, pH 7.35 perfusion with either solution, nor when ouabain mumol was added. The spectra are briefly discussed in comparison with those observed in the perfused heart of mammals (mostly rat), and particularly with those obtained in the frog (Rana temporaria) heart, both by analysing the bioenergetic equilibria on the basis of total tissue substrate levels measured in extracts of freeze-clamped tissue, and by evaluating cytochrome-b, flavin and pyridine nucleotide in vitro oxido-reduction read-outs in separate, similar experimental settings.

Adenosine Triphosphate↗
PubMed1993

Muscarinic modulation of neurotransmission: the effects of some agonists and antagonists.

1. Functional studies were performed to evaluate the effects of some muscarinic agents at the neuromuscular junction of the mouse. 2. The presynaptic control of acetylcholine release and the postsynaptic activation of the nicotinic receptor have been analyzed by means of extracellular recording. The amplitude of spontaneous and of evoked acetylcholine release, the frequency of spontaneous acetylcholine release and the time course of the quantal release have been measured by means of an EPC7 patch clamp amplifier. 3. This electrophysiological method revealed multiple dose-related effects of some agonists and antagonists on the above parameters. Concentration-response curves related to the parameters underlying the function of this cholinergic synapse were obtained and the apparent EC50 values calculated. 4. Many of the interactions of the agonists and antagonists could inhibit neuromuscular transmission. The rank order potencies related to the inhibition of the evoked signals were carbachol > oxotremorine > d,l-muscarine for the agonists and methoctramine > 4-DAMP > l-hyoscyamine > AFDX-116 > ipratropium > pirenzepine for the antagonists. 5. These findings suggest a more complicated pattern related to the muscarinic action at the mouse neuromuscular junction with the involvement of some post-synaptic located sites.

Acetylcholine↗
PubMed1993

Postsynaptic effects of methoctramine at the mouse neuromuscular junction.

Functional studies were performed to evaluate the effects of methoctramine at the neuromuscular junction of the mouse. The presynaptic control of acetylcholine release and the postsynaptic activation of the nicotinic receptor have been analysed by means of the extracellular recording with an EPC7 Patch Clamp amplifier. This electrophysiological method revealed a dose-related inhibitory effect of methoctramine on the studied parameters. The dramatic reduction of the kinetics of the quantal conductance change indicates an action at the postsynaptic level. The effects of methoctramine have been compared with those of the muscarinic agonist oxotremorine. Concentration/response curves for the two drugs were obtained and the apparent EC50 values calculated. The effects of oxotremorine were not antagonized by 1 microM methoctramine. These findings suggest an interaction of some muscarinic agents on the postsynaptic receptor-ion-channel complex at the mouse neuromuscular junction.

Acetylcholine↗
PubMed1992

[Aneurysms of the peripheral arteries].

The Authors examine aetiological, pathological, and clinical patterns of the peripheric aneurysms and emphasize the frequency with which an aneurysm, even when asymptomatic, can complicate and cause acute ischaemia of a limb with high risk of amputation. They present their personal experience of ten operated cases, some of choice, others in emergency, and report the immediate and late results.

Aneurysm↗
PubMed1991

[Giant diverticulum of the bladder. A case report].

Vesical diverticula are a common pathology of the urinary bladder, generally secondary to cervico-urethral obstruction. Frequency of giant diverticula is not reported in the literature. The Authors present a case of giant vesical diverticulum (20 x 30 cm in diameter) due to prostatic adenoma in which any referable symptomatology was absent. The Authors debate the reasons for which progressive development of the diverticulum has been related with the improvement of the frequency and urgency previously presented by the patient.

Aged↗
PubMed1991

Continuous read-out of cytochrome b, flavin and pyridine nucleotide oxido-reduction processes in the perfused frog heart and contracting skeletal muscle.

The time-sharing instrument for continuous read-out of the fluorescence levels of NAD(P)H and oxidized-flavoproteins, which also makes simultaneous dual beam differential absorption measurements of cytochrome b, has been applied to the study of the metabolic control of the frog heart, perfused in vitro with normal and variously modified Ringer solutions, and to the frog skeletal muscle in situ. In the ionically depolarized resting heart, the long term kinetic analysis of the redox processes during oxygen/anoxia transitions has proved to be an adequate method for identifying and following three fundamental intracellular redox compartments: (1) the respiratory system, (2) the microsomal system, and (3) the glycolytic system. The provision of substrates and/or suitable inhibitors has allowed the description of functional interrelationships within the mitochondrial and the cytoplasmic spaces. The ouabain major site of response has been located on the cytosolic pyridine nucleotides, with a very small response in the mitochondrial space. The switching on and off of substantial fractions of the NAD(P)+/NAD(P)H and Fpoxidized/Fpreduced pools has been observed, which helps to clarify the large phase shift between the overall pyridine nucleotide and flavin oxidation-reduction processes, during the cycle of the spontaneously beating heart and during skeletal muscle contraction and recovery, here originally prompted out.

Animals↗