PubMed Health⌕ Search

Biomedical subjects

F Rosa

Publications and source records attributed to F Rosa.

At least 37 records · Page 2Linked to original sources
PubMed1996

Neurophysiological methods testing the psychoneural basis of attention deficit hyperactivity disorder.

Theories concerning the etiology of attention deficit hyperactivity disorder have evolved from the 1950s, when it was believed that an injury to or dysfunction of the diencephalon was the cause of the syndrome, to the present day, when delayed brain maturation is postulated as an explanation. Delay in laying down myelin can be investigated by newly developed techniques like computerized EEG and transcranial magnetic stimulation. In this study, a group of 15 children 3-7 years of age suffering from attention deficit were investigated using both methods in combination and were compared to a control group of 23 age-matched normal children. On the computerized EEG spectral analysis significant differences to the control group were found in areas O1 and O2 (P < 0.05, Student's t-test). With transcranial magnetic stimulation, the overall difference in right/left stimulation was statistically significant (P < 0.001). The results suggest delayed myelination at the brain stem reticular formation where the alpha rhythm is activated and at the corticospinal pathway as parts of a widespread involvement.

Attention Deficit Disorder with Hyperactivity↗
PubMed1996

LEAFS determination and concentration of metals in Great Lakes ecosystem.

A Laser-Excited Atomic Fluorescence Spectrometric (LEAFS) method for Tl determination has been extended to investigate the direct determination (without preconcentration nor acid digestion) of total Pb, for which the method validation was successfully achieved by using a standard reference material as well as many spike recoveries of digested and undigested unfiltered water samples. The method was applied to study total and dissolved Pb in many water columns collected from different stations in Lake Ontario. Dissolved Pb was found to be about twice as much as dissolved Tl, and total Pb about seven times higher than total Tl. Seventy five percent of Pb is in particulate form versus 11% for Tl. Also, a simple cold dissolution procedure using HNO(3) and HF (not a hot acid digestion) is proposed to "liquefy" sediments in a form suitable for LEAFS analysis and was used to analyze a sediment core, where pore water samples were also collected. The interaction dynamics of Tl within the natural environment of a water/pore water/sediment system from Lake Erie was assessed. The calculations of fluxes suggest a strong similarity between Tl and Cd geochemical transport. The paper also presents for the first time a genuine sediment pore water profile of Tl concentration, which ranged from sub- to 40 ng/l and which was directly determined by LEAFS.

Journal Article↗
PubMed1996

An activated form of type I serine/threonine kinase receptor TARAM-A reveals a specific signalling pathway involved in fish head organiser formation.

The role of Transforming Growth Factor beta (TGF-beta)-related molecules in axis formation and mesoderm patterning in vertebrates has been extensively documented, but the identity and mechanisms of action of the endogenous molecules remained uncertain. In this study, we isolate a novel serine/threonine kinase type I receptor, TARAM-A, expressed during early zebrafish embryogenesis first ubiquitously and then restricted to dorsal mesoderm during gastrulation. A constitutive form of the receptor is able to induce the most anterior dorsal mesoderm rapidly and to confer an anterior organizing activity. By contrast, the wild-type form is only able to induce a local expansion of the dorsal mesoderm. Thus an activated form of TARAM-A is sufficient to induce dorsoanterior structures and TARAM-A may be activated by dorsally localized signals. Our data suggest the existence in fish of a specific TGF-beta-related pathway for anterior dorsal mesoderm induction, possibly mediated by TARAM-A and activated at the late blastula stage by localized dorsal determinant.

Amino Acid Sequence↗
PubMed1996

Inhibitory interactions controlling organizer activity in fish.

An experimental system allowing the observation of 2 active organizing centers during zebrafish development is described. It was achieved by injection into a single marginal cell at the 16-cell stage of TARAM-A-D mRNA. TARAM-A-D was previously described as the mutated constitutive form of a type I receptor for transforming growth factor beta. In 80% of the injected embryos, 2 distinct organizers were observed at the onset of gastrulation. At the end of gastrulation, these embryos showed duplicated axial structures. Nevertheless, only 25% of the injected embryos displayed a recognizable axis duplication after 1 day of development. This paradox is taken as an evidence for suppressive effects exerted in a reciprocal manner when more than 1 organizing center is present.

Animals↗
PubMed1996

Decreased cardiovascular responses to cisterna magna NaCl injection in hypertensive rats.

Albino rats were made hypertensive by 1% NaCl in the drinking water for 4-5 months, systolic (SBP) and distolic blood pressure (DBP) were 164.0 +/- 10.1 mm Hg and 118.7 +/- 4.6 mm Hg respectively, vs. control rats whose SBP and DBP were 119.0 +/- 4.4 mm Hg and 86.8 +/- 4.3 mm Hg respectively. Psychosocial stress (1 hour daily for 4-5 months) only raised SBP to 140.0 +/- 5.2 mm Hg; DBP remained unaltered. One percent NaCl intake combined with psychosocial stress, increased SBP and DBP but not significantly beyond the level observed with single 1% NaCl administration. Formerly described control and hypertensive rats were anesthetized with sodium pentobarbital (40 mg/kg) and stereotaxically injected into de cisterna magna (i.c.) with 20 microliters of 1.5 M NaCl solution. During i.c. injection, intraarterial SBP, DBP and heart rate (HR) were continuously recorded. After i.c., 1.5 M NaCl injection, mean arterial pressure (MAP) increased 21.0 +/- 4.0 mm Hg and HR 51.0 +/- 5.0 beats/min in control rats. Rats made hypertensive by 1% NaCl intake showed a significantly lower increase of MAP, 11.0 +/- 1.8 mm Hg; HR increased 37.0 +/- 4.3 beats/min. Rats submitted only to psychosocial stress displayed a response similar to the one described in control rats. Hypertensive rats submitted to both 1% NaCl intake and psychosocial stress had a more intense reduction of the hypertensive and tachycardic response, 8.0 +/- 2.2 mm Hg and 20.0 +/- 3.2 beats/min respectively. Control i.c. injection with the same volume of saline (0.15 M NaCl) did not change significantly SBP, DBP or HR in a separate group of rats. Left ventricle weight (0.754 +/- 0.0333 g) was augmented in the 1% NaCl treated group (0.795 +/- 0.038 g), and increased its protein content by 13.1% (changes not statistically significant). The highest increase of the left ventricle weight (23.7% above control) with no change in its protein content was observed in rats submitted to 1% NaCl intake plus psychosocial stress. In conclusion, chronic high NaCl intake increased blood pressure; psychosocial stress acted as a weak stimulus for SBP and DBP increase, and central nervous system sodium chloride sensitivity for delivering a peripheral sympathetic discharge was found decreased in rats made hypertensive by a high salt intake.

Animals↗
PubMed1996

[Direct negative inotropic effect of cocaine in rat ventricle strip].

Cocaine, when used as a recreative drug, can induce cardiovascular toxic effects such as acute reduction of left ventricle ejection fraction, which indicates a negative inotropic effect of the drug. The purpose of this study was to clarify the direct negative inotropic effect of cocaine in in vitro conditions. Rat right ventricle strips were incubated in Krebs solution gassed with 95% O2 and 5% CO2 at 37 degrees, and electrically driven with 2 ms square pulses, 17 mA, at 110 systoles/min. Separate experiments were conducted to study cocaine effect at 210 and 310 systoles/min. The contractile force was recorded through a strain-gauge isometric transducer. Cocaine increased contractile force at doses of 0.3-10.0 micrograms/ml, up to 53% over basal contraction. In the presence of 4 x 10(-8) M atenolol, low doses of cocaine did not increase contractile force and at doses between 3.0-10.0 micrograms/ml revealed a depressant activity on heart muscle contractions. Doxazosin (1.0 microM) and yohimbine (0.1 microM) did not modify the positive inotropic effect of cocaine, showing that alpha 1 and alpha 2 adrenergic receptors were not involved in this cocaine ventricle action. Increasing ventricle strip stimulation rate to 210 and 310 systoles/min for 30 seconds, the contractile force was risen by 55% and 95%, respectively. Cocaine at doses 1.0-3.0 micrograms/ml did not modify the physiological increase of contractile force seen upon ventricle rate increase. The mechanism involved in the contractile force increment after ventricle rate increase is a transient rise of cytosolic Ca2+, mainly derived from the sarcoplasmic reticulum and from extracellular fluid. Atenolol (4 x 10(-8) M) exposure of the right ventricle strip intensified the negative inotropic effect of cocaine (3.0-10 micrograms/ml) seen by ventricle stimulation at 210 and 310 systoles/min. The myocardial direct depressant effect of cocaine, in the presence of atenolol, was gradually reversed by extracelular Ca2+ increase at 3.2 and 5.0 mM, respectively. In conclusion, the mechanism of myocardial direct depressant effect of cocaine is related to the beating frequency of the ventricle, which may be associated to interference with the Ca2+ release process from the myocite sarcoplasmic reticulum, and not to calcium entry blockade from extracellular fluid. However, a dpressant effect of cocaine on phase "0" of depolarization, related to its local anesthetic properties can not be ruled out.

Animals↗
PubMed1995

Low urinary dopamine excretion associated to low sodium excretion in normotensive Piaroa Amazonian ethnia compared to urban subjects.

The objective of this work was to compare urinary dopamine, noradrenaline, adrenaline, sodium and potassium excretion in a group of normotensive Piaroa Amazonic ethnia who do not use salt in their regular food intake, against a group of urban normotensive citizens known to have a high salt intake in their regular meals. Twenty adult normotensive Piaroa subjects living in the Amazonas forest, 11 men and 9 women, 23-72 years old, and 33 normotensive urban citizens, 25-70 years old, 17 men and 17 women, were included in the study. After a 10 min. rest, an average of three supine systolic (SBP) and diastolic (DBP) blood pressure recordings was obtained. Piaroas subjects SBP and DBP were 111.3 +/- 2.9 mmHg and 62.7 +/- 1.9 mmHg respectively; urban subjects SBP and DBP were 111.8 +/- 2.2 mmHg and 70.3 +/- 1.6 mmHg respectively. Supine heart rate was lower in Piaroas (58.0 +/- 1.8 beats/min) than in urban subjects (76.5 +/- 1.9 beats/min), p < 0.05. Sodium urinary excretion was much lower in Piaroas (12.6 +/- 5.2 mmol/24 h) when compared to urban subjects (210.7 +/- 24.5 mmol/24 h), p < 0.01. No difference was found in daily urinary potassium excretion between Piaroas and urban subjects (50.4 +/- 7.2 mmol/24 h vs 45.1 +/- 7.4 mmol/24 h). Urinary dopamine excretion was lower in Piaroas (314.7 +/- 40.1 micrograms/24 h) in comparison to urban subjects (800.4 +/- 59.2 micrograms/24 h), p < 0.05. Daily urinary noradrenaline and adrenaline excretion were 67.9% and 85.4% respectively lower in Piaroas than in urban subjects. In conclusion, lower amounts of sodium daily intake are associated to lower kidney dopamine production in Piaroas as compared to urban subjects. Apparently indigenous tribes might require less kidney dopamine synthesis to excrete the very small amounts of salt they consume in their regular food intake. The opposite was found in urban subjects; more kidney dopamine synthesis would be required for larger amounts of urinary sodium excretion. In this population, essential hypertension has been associated to a failure of the natriuretic mechanism triggered by dopamine onkidney tubules.

Adult↗
PubMed1995

[Abnormal autonomic cardiovascular responses in patients with sickle cell anemia].

PURPOSE: To evaluate the presence of anomalies of the autonomic reflex cardiovascular response in patients with chronic sickle-cell anaemia. PATIENTS AND METHODS: The study was extended to 30 patients with sickle-cell anaemia, 10 patients with iron-lack anaemia and 30 healthy subjects. Age and sex distribution was similar in each group. To be included in the study, patients should have had no painful crisis or blood transfusion in the 6 months previous to the assay. Clinico-laboratory survey, chest x-ray and EKG were performed in every case. Blood cell count and abnormal haemoglobin study on cellulose acetate were carried out as well. The evaluation of reflex autonomic responses was performed by means of active orthostatism, cold pressor test, Valsalva maneuver and urine catecholamine output. The statistical analysis was performed with the variance analysis (ANOVA) for multiple groups. RESULTS: The following abnormalities were found: 12 patients had haemoglobin SS, 8 had haemoglobin SS and F, 3 had haemoglobin SC, 2 had haemoglobin S and beta-thalassaemia, and 5 had combined haemoglobin SS,F and A2. Systolic pressure and heart frequency in the supine position were similar in all groups. Diastolic pressure was lower in the sickle-cell anaemia group with respect to the normals. Patients with sickle-cell disease had lower heart frequency in the active orthostatism test with regard to the other groups, along with paradoxal changes in systolic pressure and lesser increase of the diastolic pressure. Significantly lower response to the cold pressor test was seen in the sickle-cell patients as compared with the iron-lack cases and the normal controls. Reduced sympathetic tachycardia was seen with the Valsalva maneuver, whereas the bradycardia was similar to the other groups. The urine noradrenaline in output was significantly lower in the sickle-cell patients, it was normal in the other groups (p < 0.01). CONCLUSION: These results suggest a defective sympathetic activity of heart and arteries in patients with sickle-cell anaemia.

Adolescent↗
PubMed1994

Recent increases in numbers and risk of fatalities in young children ingesting iron preparations.

Iron preparations are the most frequent cause of pediatric ingestion fatalities. The purpose of this study was to quantify the impression of an increase in iron deaths in young children and to postulate on the reasons. Using the data provided by the American Association of Poison Control Centers, overall annual mortality rate from iron preparations and among children < 6 y was calculated and changes in incidence were recorded. Between 1983 and 1991, there was a 2 to 3-fold increase in the numbers of reported ingestions of iron preparations by toddlers. In the general population the annual mortality rate/100 exposures to iron preparations increased from 0.05 during 1983-1990 to 0.116 in 1991 (p < 0.01). A similar trend was noted in children < 6 y with a rate of 0.004 in 1983-1990 compared with 0.12 in 1991 (p < 0.01). Hence, the increase in mortality was beyond what would be predicted from the increased number of ingestions noted. It is likely that increased awareness of pregnancy-induced anemia results in abundant use of iron pills. These pills have the appearance of candies, which should be changed immediately by legislation. During this period, the volume of iron preparations prescribed increased only marginally (16%), suggesting that over-the-counter use of iron pills increased substantially. In addition to warning labels and child-resistant packaging, an aggressive educational plan directed at the general population and physicians should be instituted immediately.

Child, Preschool↗
PubMed1994

[Variation in drug prescription costs and general practitioners in an area of North-East Italy. The use of current data].

In this paper we analyse all General Practitioners (GP) prescriptions in a Friuli-Venezia Giulia area (North-eastern Italy). The sample included of 181 GPs and 242,564 patients with 1,191,122 prescribed items. The regional Health Data Base is the source of all data. Data analysis was performed according to the multiple regression and LISREL models. We assessed for all GPs the years of medical profession, patients listed, percent of patients exent from prescription rates, patients over 60, number of active compounds prescribed and related drug companies. Two factors, the number of active compounds prescribed and patients listed, significantly contributed to the multiple regression model. The model explained 56% of variation in prescribing pointing out the importance of those factors in influencing the cost per patient. LISREL model shows a causal chain going from the years of medical profession to cost per patient passing through the number of active compounds and drug companies related. In fact, the older the GP the less the cost per patient and number of active compounds used. A main finding is that the cost per patient is highly influenced by the number of different active compounds prescribed. As in other studies the percent of patients exent from prescriptions rates and aged over 60 are somehow fundamental in influencing the cost per patient. Finally we discussed models and literature on the issue.

Aged↗
PubMed1990

Mesoderm induction in Xenopus laevis distinguishes between the various TGF-beta isoforms.

Induction of mesoderm in ectodermal explants of Xenopus laevis blastula embryos had previously been shown to respond selectively to TGF-beta 2, with TGF-beta s 1 and 5 having no activity in this assay. As TGF-beta s 1, 2, and 3 are frequently coexpressed in tissues, we wished to examine the activity of TGF-beta 3 relative to that of TGF-beta s 1 and 2 in this assay as well as in other in vitro assays. We report here that when the activity of recombinant TGF-beta 3 is normalized to that of TGF-beta 1 in the assay for growth inhibition in CCL-64 cells, it is also equal to that of TGF-beta 1 in assays for stimulation of both anchorage-independent growth of rat NRK cells and chemotaxis of human monocytes. In contrast, in the assay for mesoderm induction, recombinant TGF-beta 3 is 10-fold more active than TGF-beta 2, inducing expression of muscle specific alpha-actin at concentrations as low as 1 ng/ml. These results suggest that more complex systems, in contrast to individual cell types, may respond selectively to the various TGF-beta isoforms and that there might be biological consequences of TGF-beta isoform switching in vivo.

Animals↗
PubMed1990

Isolation and characterization of TGF-beta 2 and TGF-beta 5 from medium conditioned by Xenopus XTC cells.

TGF-beta 2 and -beta 5 have been purified from medium conditioned by Xenopus cultured cells (XTC) and identified based on their N-terminal amino acid sequence analysis and biological activity. When applied in high concentrations, Xenopus TGF-beta 2, like porcine TGF-beta 2, induces expression of mesodermal markers from cultured Xenopus ectodermal explants, whereas TGF-beta 5 is inactive in this assay. However, the TGF-beta 's could be separated from the major mesoderm-inducing activity present in XTC medium. Xenopus TGF-beta 2 and -beta 5 are approximately equivalent to TGF-beta 1 in their abilities to inhibit the growth of mink lung CCL-64 cells, induce anchorage-independent growth of rat NRK cells, inhibit the proliferation and antibody secretion of human B-lymphocytes, and stimulate chemotaxis of human monocytes. These data establish the functional activity of TGF-beta 5 and suggest that more complex multicellular systems, in contrast to most isolated cells, discriminate between the different TGF-beta s.

Amino Acid Sequence↗
PubMed1989

[Therapeutic aspects of hairy cell leukemia].

This work considers the new advances in hairy cell leukemia therapy. During the last decades the only useful treatments were splenectomy, or, in case of failure or relapse, various chemotherapeutic approaches. Sometimes leukapheresis, radiotherapy, androgens, allogenic bone marrow transplantation, corticosteroids and lithium salts were used with few good results. Interferon and 2-deoxicoformycin recently introduced for the treatment of HCL have determined a dramatic change in the outlook of this disease, producing a high percentage of complete and partial remission.

Antineoplastic Agents↗
PubMed1988

Mesoderm induction in amphibians: the role of TGF-beta 2-like factors.

Mesoderm induction in the amphibian embryo can be studied by exposing animal region explants (destined to become ectoderm) to appropriate stimuli and assaying the appearance of mesodermal products like alpha-actin messenger RNA. Transforming growth factor beta 2 (TGF-beta 2), but not TGF-beta 1, was active in alpha-actin induction, while addition of fibroblast growth factor had a small synergistic effect. Medium conditioned by Xenopus XTC cells (XTC-CM), known to have powerful mesoderm-inducing activity, was shown to contain TGF-beta-like activity as measured by a radioreceptor binding assay, colony formation in NRK cells, and growth inhibition in CCL64 cells. The activity of XTC-CM in mesoderm induction and in growth inhibition of CCL64 cells was inhibited partially by antibodies to TGF-beta 2 but not by antibodies to TGF-beta 1. Thus, a TGF-beta 2-like molecule may be involved in mesoderm induction.

Actins↗
PubMed1988

Accumulation and decay of DG42 gene products follow a gradient pattern during Xenopus embryogenesis.

The DG42 gene is expressed during a short window during embryogenesis of Xenopus laevis. The mRNA for this gene can be first detected just after midblastula, peaks at late gastrula, and decays by the end of neurulation. The sequence of the DG42 cDNA and genomic DNA predicts a 70,000-Da protein that is not related to any other known protein. Antibodies prepared against portions of the DG42 open reading frame that had been expressed in bacteria detected a 70,000-Da protein in the embryo with a temporal course of appearance and decay that follows that of the RNA by several hours. Localization of the mRNA in dissected embryos and immunohistochemical detection of the protein showed that DG42 expression moves as a wave or gradient through the embryo. The RNA is first detected in the animal region of the blastula, and by early gastrula is found everywhere except in the outer layer of the dorsal blastopore lip. By midgastrula DG42 protein is present in the inner ectodermal layer and the endoderm; it disappears from dorsal ectoderm as the neural plate is induced and later decays in a dorsoventral direction. The last remnants of DG42 protein are seen in ventral regions of the gut at the tailbud stage.

Animals↗