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Biomedical subjects

M Gatto

Publications and source records attributed to M Gatto.

At least 19 recordsLinked to original sources
PubMed2001

Carbon emissions. The economic benefits of the Kyoto Protocol.

The third Conference of the Parties in Kyoto set the target of reducing greenhouse-gas emissions by an average of 5.3% with respect to 1990 values by 2008-2012. One of the main objections to the protocol's ratification is that compliance would pose an unbearable economic burden on the countries involved. But we show here that this is not the case if costs apart from the direct costs of energy production are also considered. Costs are also incurred in rectifying damage to human health, material goods, agriculture and the environment related to greenhouse-gas emissions.

Journal Article↗
PubMed2000

Quantifying the dynamics of prion infection: a bifurcation analysis of Laurent's model.

Laurent (1996a, Médecine/sciences12, 774-785; 1996b, Biochem. J.318, 35-39; 1998, Bio-phys. Chem.72, 211-222) proposed a model for the dynamics of diseases of the central nervous system caused by prions. It is based on the protein-only hypothesis (Prusiner et al., 1981, Proc. Natl. Acad. Sci. U.S.A.78, 6675-6679), which assumes that infection can be spread by particular proteins (prions) that can exist in two forms that share the same sequence, but have a different structure. The normal form is harmless, while the infectious isoform of the prion protein catalyses a transconformation from the native isoform to itself within a specialized compartment of the brain cells. This paper systematically explores the model behavior with the aim of quantifying the fundamental parameters characterizing the dynamics of prion infection. To this end we use data from the literature to fix orders of magnitude for the rates of synthesis and degradation of the native form of prion protein and for the shape of the autocatalytic function. The dynamical behavior is classified with respect to two unknown parameters (bifurcation analysis): the rate of spontaneous transconformation and the rate of output of the infectious isoform from the specialized compartment. We thus find that the bistability properties evidenced by Laurent are confined to a certain range of parameters and that permanent oscillations of the two isoforms concentrations are possible. The bifurcation analysis allows us to estimate approximate ranges for the values of the two unknown parameters and consequently to derive incubation times and compare them with actual data for hamster. Also, our study predicts that the output rate of the infectious isoform is relatively insensitive to variations of model parameters.

Animals↗
PubMed1999

Effects of gender of subjects and experimenter on susceptibility to motion sickness.

BACKGROUND: It has been reported that females are more susceptible to motion sickness than males, but these reports have failed to take into account the possible effects of the gender of the experimenter and the subjective nature of reports of symptoms of motion sickness. To deal with the first possible confound, we used male and female experimenters. To deal with the second issue, we recorded gastric myoelectric activity so as to be able to quantify gastric tachyarrhythmia, an objective measure that has been shown previously to correlate highly with severity of symptoms. METHOD: There were 34 male and 34 female participants were assigned to either a male or female experimenter. Symptoms of motion sickness were induced by placing participants in an optokinetic drum for an 8-min baseline period followed by a 16-min rotation period. Electrogastrograms (EGGs) were continuously recorded, and reports of symptoms were obtained from the participants every 3 min during rotation. RESULTS: Comparison of male and female subjects' symptom scores revealed that females had higher symptom scores than males; however, no significant main effects for gender of the subject or experimenter were found. However, on a post-session questionnaire, females reported experiencing significantly more GI symptoms than males. Gender comparisons of the change in gastric tachyarrhythmia power from baseline to rotation yielded no significant differences. CONCLUSIONS: Females report more overall symptoms of motion sickness and significantly more GI symptoms than males, but do not show greater increases in gastric tachyarrhythmia during exposure to a rotating drum.

Adolescent↗
PubMed1999

Slow deep breathing prevents the development of tachygastria and symptoms of motion sickness.

BACKGROUND: The purpose of this study was to see if slow deep breathing, a non-pharmacological procedure known to increase parasympathetic nervous system (PNS) activity, would prevent the development of gastric dysrhythmias and symptoms of motion sickness when subjects were exposed to a rotating optokinetic drum. METHODS: Participating in this study were 46 healthy males and females aged 17-26 who were pre-tested in the rotating drum and found to be susceptible to motion sickness. They were randomly placed into one of the following three conditions: Slow Deep Breathing (n = 18), Counting Breaths (subjects were asked to count their breaths and asked for the count every 3 min, n = 16), and Control (subjects breathed normally, n = 12). Electrogastrograms were recorded from all subjects during a 6-min baseline and a 16-min rotation period. Subjects were asked about their symptoms every 3 min. RESULTS: A significant difference in percent tachygastria from baseline to rotation was found between the three conditions. Percent tachygastria increased during rotation for the Counting Breaths group and the Control group, but remained the same as baseline for the Slow Deep Breathing group. The Slow Deep Breathing group (5.3) reported significantly fewer symptoms than the Counting Breaths group (9.0), but not the Control group (7.8). CONCLUSION: In conclusion, slow deep breathing in a situation previously demonstrated to provoke tachygastria prevented the development of gastric dysrhythmias and decreased symptoms of motion sickness.

Adolescent↗
PubMed1998

Acidic deposition, plant pests, and the fate of forest ecosystems.

We present and analyze a nonlinear dynamical system modelling forest-pests interactions and the way they are affected by acidic deposition. The model includes mechanisms of carbon and nitrogen exchange between soil and vegetation, biomass decomposition and microbial mineralization, and defoliation by pest grazers, which are partially controlled by avian or mammalian predators. Acidic deposition is assumed to directly damage vegetation, to decrease soil pH, which in turn damages roots and inhibits microbial activity, and to predispose trees to increased pest attack. All the model parameters are set to realistic values except the inflow of protons to soil and the predation mortality inflicted to the pest which are allowed to vary inside reasonable ranges. A numerical bifurcation analysis with respect to these two parameters is carried out. Five functioning modes are uncovered: (i) pest-free equilibrium; (ii) pest persisting at endemic equilibrium; (iii) forest-pest permanent oscillations; (iv) bistable behavior with the system converging either to pest-free equilibrium or endemic pest presence in accordance with initial conditions; (v) bistable behavior with convergence to endemic pest presence or permanent oscillations depending on initial conditions. Catastrophic bifurcations between the different behavior modes are possible, provided the abundance of predators is not too small. Numerical simulation shows that increasing acidic load can lead the forest to collapse in a short time period without important warning signals.

Acid Rain↗
PubMed1997

Multicenter, double-blind, comparative clinical study on the efficacy and acceptability of a monthly injectable contraceptive combination of 150 mg dihydroxyprogesterone acetophenide and 10 mg estradiol enanthate compared to a monthly injectable contraceptive combination of 90 mg dihydroxyprogesterone acetophenide and 6 mg estradiol enanthate.

Healthy, regularly menstruating women, aged 14-38 years, were enrolled in a comparative, double-blind, phase III, clinical trial to evaluate the contraceptive efficacy and acceptability of a combination of 90 mg dihydroxyprogesterone acetophenide with 6 mg estradiol enanthate compared to the commercially available contraceptive combination of 150 mg dihydroxyprogesterone acetophenide with 10 mg estradiol enanthate. Subjects received the contraceptive combination intramuscularly, between the 7th and 10th day of each menstrual cycle, during 12 consecutive menstrual cycles. Approximately 60% of the subjects in both groups completed the study. Principal reasons for discontinuation were personal, nonmedical reasons. Principal medical reasons for discontinuation were menstrual-related, irregular bleeding being the most frequent. Differences in menstrual patterns between the two groups did not lead to differences in discontinuation rates. Three contraceptive failures occurred during the trial, one in Group A (90/6 mg) and two in Group B (150/10 mg), indicating that the lower dose formulation is at least as efficient as the higher dose.

Adolescent↗
PubMed1994

L-dopa malabsorption in a parkinsonian patient with Strongyloides stercoralis duodenitis.

We report a parkinsonian patient initially responding to L-dopa who developed a severe loss of drug efficacy due to Strongyloides stercoralis duodenitis. The patient was put on mebendazole and metronidazole, and the parasitosis abated, allowing L-dopa reduction by 33%. Our patient illustrates the advisability of searching for Strongyloides stercoralis when L-dopa malabsorption is suspected in Parkinson's disease.

Aged↗
PubMed1993

Chaotic population dynamics can result from natural selection.

The question of whether animal populations display chaotic dynamics has motivated a thriving body of research for two decades. Yet unambiguous evidence for chaos in the wild remains scarce. Accordingly, it has been proposed that evolutionary forces act to preserve populations from chaos as well as oscillations. We have tested for this hypothesis by considering the dynamics associated with evolutionarily stable life histories (including age of maturity, adult survivorship and recruitment to adulthood) in a simple, but general, demographic model. Contrary to expectation, individual selection operating on demographic traits should often lead to oscillatory or chaotic dynamics for species with late feasible ages of maturity and many age classes. Also, the optimality of chaos is more likely whenever trade-offs constrain recruitment to rapidly decrease with increasing adult survival or decreasing age of maturity. Our results bring evolutionary support to the possibility that chaotic population dynamics might be much more widespread than inferred until now from data analyses. Furthermore, these findings provide novel support for the view that chaos could be an optimal regime for several biological systems.

Aging↗
PubMed1993

Bruxism secondary to chronic antidopaminergic drug exposure.

Eight cases of diurnal bruxism (DB) secondary to long-term antidopaminergic drug exposure are reported. Five exhibited a grinding pattern, one a clenching form, and two a mixed type. An odontological etiology was absent throughout. EMG recordings disclosed two distinct patterns of muscle activity, one with brief rhythmic, forceful contractions and the other featuring sustained prolonged contractions. Surface EMG and EEG monitoring during a 24-h period confirmed the absence of bruxism during sleep. Several drug trials failed to provide relief. Our findings support DB as a focal tardive dystonia syndrome.

Aged↗
PubMed1990

Blepharoclonus and parkinsonism associated with aqueductal stenosis.

A 28-year-old man with a history of congenital hydrocephalus due to aqueductal stenosis shunted at 45 days of age is presented. At age 4 years the valve had to be removed because of septicemia. Twenty-three years later he developed parkinsonian signs and abnormal, involuntary rhythmic contractions of the eyelids. The latter were elicited on gentle eye closure. Parkinsonism promptly improved after ventriculoperitoneal shunting, but blepharoclonus persisted unchanged.

Adult↗
PubMed1990

Treatment of Tourette's syndrome with calcium antagonists.

Six males and one female with chronic tic disorders, whose ages ranged from 12 to 31 years, were evaluated before treatment, after 1 month on placebo, after a single 10 mg nifedipine dose (three patients), and monthly while on flunarizine 10-15 mg (mean dose of 13 mg). None of the patients receiving nifedipine improved, but treatment with flunarizine significantly decreased both motor and phonic tic severity and frequency in all but one patient. Side effects included mild transient headaches in one patient, depression in one, and bradykinesia in two. Although a double-blind study is essential to validate our findings, results suggest that flunarizine is a useful drug in the treatment of Gilles de la Tourette syndrome.

Adolescent↗
PubMed1990

[Treatment of blepharospasm with botulinum toxin].

Blepharospasm is a relatively frequent cranial dystonia which may be seen either alone or related to orofacial-mandibular dystonia (Meige's syndrome). In its maximum degree it can cause functional blindness.Twelve patients with blepharospasm (4 essential and 8 Meige's syndrome) who had been previously treated unsuccessfully with drugs (trihexyphenidyl, biperiden, carbamazepine, lithium, baclofen, lisuride, imipramine, clonazepam and butyrophenones) were treated for 12 months with periocular injections of botulinum toxin (BOTOX). A "low" dose of 12,5 U per eye was employed. With this dose, eleven out of twelve patients experienced significant improvement which lasted from five to fifteen weeks. The only nonresponder obtained complete relief upon duplicating the dose. The only side effect was uni or bilateral ptosis in six patients which improved completely in seven to twenty one days. One patient developed a peripheral facial palsy with complete remission in nineteen days. No systemic side effects were noted. There was only one desertion from this study due to depression enhanced by prolonged (21 days) ptosis. All patients (including the deserter) agreed that treatment with BOTOX provided more relief than any other previous therapeutic method. Our results confirm those obtained by others but a more prolonged study is needed to better evaluate long term effects.

Aged↗
PubMed1989

Movement disorders and depression due to flunarizine and cinnarizine.

Over the last few years, cases of movement disorders induced by flunarizine and cinnarizine have been increasingly reported. We describe a series of 101 patients, whose ages ranged from 37 to 84 years (mean 69.1), developing abnormal movements frequently associated with depression, secondary to treatment with either or both drugs. Symptoms closely resembled those induced by neuroleptic drugs and remitted on drug discontinuance in all but five cases after 5-22 months' follow-up. Whether or not such undesirable side effects are attributable to calcium antagonism and/or dopamine receptor blockade, long-term treatment with flunarizine or cinnarizine should be discouraged, particularly in the elderly.

Adult↗
PubMed1988

Treatment of Parkinson's disease with subcutaneous lisuride infusions.

Four patients with Parkinson's disease and severe fluctuating responses to levodopa and oral dopamine agonists were treated with continuous administration of lisuride infusions, administered by means of an externally worn pump. Levodopa dosage ranged from 300 to 687 mg/day and was kept stable throughout the study. In addition increasing doses of lisuride were injected subcutaneously in the abdomen. Lisuride doses ranged from 41 to 104 micrograms/h. A marked improvement in mobility was observed in every patient while severe biphasic dyskinesais almost remitted in one of them. The most common side-effect was the presence of subcutaneous nodules appearing at the injection site. Two cases had mild hemorrhagic complications and one initially had nausea. One patient developed acute psychiatric disturbances severe enough to be excluded from the study. Our findings suggest that lisuride subcutaneous infusions can be useful in severily handicapped parkinsonian patients, however local and psychiatric side-effects may be a serious threat in the long-term care.

Aged↗
PubMed1987

Flunarizine- and cinnarizine-induced extrapyramidal reactions.

Cinnarizine and flunarizine are selective calcium blockers that have been used to treat and prevent vertigo. We studied 15 patients who had extrapyramidal syndromes after taking these drugs. Eleven patients had parkinsonism, one with persistent akathisia as well; one had an orofacial tremor; one, acute akathisia alone; and one an acute dystonic reaction. All but one improved when the drug therapy was discontinued. Seven patients were also depressed during treatment. Cinnarizine and flunarizine must therefore be added to the list of potentially risky drugs known to induce extrapyramidal reactions and depression.

Adult↗
PubMed1985

[Piebaldism associated with cancer].

A family in which piebaldism is inherited in a dominant pattern is described. In this kindred the cutaneous signs were associated to a high incidence of cancer. Malignancy usually became apparent in the fourth decade and did not correspond to any fixed histopathologic type. Associated cutaneous alterations were: "cafe au lait" spots in two members and telangiectasias in one. A peculiar distribution of blood vessels in fundus oculi was found in one member. One patient had broad nasal bridge and low implanted ears was found in another. The initial cases were two male brothers who had central nervous system tumours. One had a pituitary adenoma and the other a grade III astrocytoma. As it is important to find biologic markers in familial cancer, we speculate, that may be in this family, the marker could be the cutaneous hypopigmentation. Numerous cutaneous syndromes associated to a predisposition to develop cancer have been described, and may be piebaldism is a new one. More observations are needed to corroborate these findings.

Adenoma↗
PubMed1982

Observer variation in assessment of jejunal biopsy specimens. A comparison between subjective criteria and morphometric measurement.

in an observer variation study, the agreement rate reached by a pair of observers who measured 85 jejunal biopsy specimens using surface/volume ratio was compared with that reached by a pair of observers who subjectively assessed the same biopsy series. Both the agreement reached between the subjective observers and that reached between the objective observers proved significant by kappa statistics. However, both total and partial kappa values were greater for the pair of objective observers in every diagnostic category. Moreover, the percentage of agreement on the grading of all biopsy specimens, independent of the diagnostic categories, proved significantly higher for the objective observers. In the pair who made a qualitative assessment, interobserver variation was particularly evident in the grading of partial villous atrophy. Contrastingly, in the pair who made a quantitative assessment, agreement was present in all but one slide. The kappa values for the observers examining the same biopsy specimens on two separate occasions indicated closer agreement rates for the two objective observers. It is concluded that morphometric measurement is more reliable than subjective criteria in the assessment of jejunal biopsy specimens and that qualitative assessment of biopsy specimens should be coupled with quantitative histology.

Atrophy↗