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Biomedical subjects

M Ventura

Publications and source records attributed to M Ventura.

At least 19 recordsLinked to original sources
PubMed1998

Failure to increase insulin-like growth factor-I synthesis is involved in the mechanisms of growth retardation of children with inherited liver disorders.

OBJECTIVE: Growth retardation is a prominent secondary feature of chronic liver disease. We investigated the hypothalamic-pituitary-liver axis in six patients with inherited liver disease and growth failure. The objectives were to determine (1) whether there were any abnormalities in the GH/IGF-I/IGFBPs/GH binding protein (GHBP) axis, (2) whether any abnormalities were nutrition-dependent, and (3) whether recombinant human (rh) GH could be efficaciously and safely administered. MEASUREMENTS: The evaluation included two standard GH provocative tests, GHRH test, night-time GH secretion, GHBP; and IGF-I, IGFBP-3 and IGFBP-1 before and after 0.1 and 0.3 U/kg/day of rhGH given i.m., for 4 days. Two patients were enrolled for rhGH treatment. RESULTS: Quantitative nutritional assessment showed the patients' calorie and protein intake to be compatible with the recommended daily allowance in liver disease. The mean baseline GH level was higher in patients than in controls (8.4 +/- 3.8 vs 2.6 +/- 2.0 mU/l, P < 0.005) and the GH response to stimuli was normal; spontaneous GH secretion was apparently normal. The mean baseline IGF-I value in the patients was significantly below the mean of controls (31.6 +/- 16.4 vs 260 +/- 35.2 micrograms/l, P = 0.00001) and similar to that of children with GH-deficiency (40.8 +/- 18.4 micrograms/l). The mean peak IGF-I response after 0.1 U/kg/day of rhGH increased (84.9 +/- 28.2 micrograms/l, P = 0.009) but remained lower than the mean IGF-I response in GH-deficient patients and in controls (P = 0.00001). The mean peak IGF-I response after 0.3 U/kg/day (113.3 +/- 52.3 micrograms/l) was significantly higher than that after 0.1 U/kg/day (P = 0.002). The mean standard deviation score (SDS) peak for IGF-I response to 0.1 and 0.3 U/kg/day of rhGH decreased significantly from -1.7 to -1.0 (P = 0.02) and from -1.9 to -0.9 (P = 0.005), respectively. There was no difference between patients and controls in serum GHBP activity or in mean baseline IGFBP-3 and IGFBP-1 levels. IGFBP-3 levels did not change significantly in response to rhGH at either 0.1 or 0.3 U/kg/day, while IGFBP-1 significantly decreased after 0.3 U/kg/day (56.3 +/- 35.6 vs 45.9 +/- 33.1 micrograms/l, P = 0.04). A significant positive correlation was present between albumin and peak IGF-I responses to rhGH at the dose of 0.1 and 0.3 U/kg/day (R = 0.83, P = 0.03; R = 0.78, P = 0.03 respectively), as well as between height SDS and baseline or stimulated IGF-I after rhGH 0.1 U/kg/day (R = 0.81, P = 0.04; R = 0.88, P = 0.01 respectively). In the two patients treated with rhGH at 22-25 U/m2/week, the growth rate doubled in one and trebled in the other during the first year of treatment, and in both was maintained in the second year without acceleration of bone maturation or evidence of adverse effects. CONCLUSIONS: The underlying cause of growth retardation in patients with inherited liver disease seems to be a progressive failure to increase IGF-I synthesis (at the conventional rhGH dose) and the consequent lack of its growth-promoting effect. The moderate increase in baseline GH values, the greater IGF-I response to the higher rhGH dose and the improvement in growth rate following rhGH administration suggest at least a degree of sensitivity to rhGH which could be of therapeutic value.

Adolescent↗
PubMed1998

[Changes in the geometry of the heart cavities in patients with cardiac tamponade undergoing pericardial drainage].

OBJECTIVES: The objective of our study was to evaluate the changes in cardiac chamber dimension--longitudinal and transversal axis--in patients with cardiac tamponade after drainage of the pericardial effusion. STUDY DESIGN: This is a five year retrospective study (from 1991 to 1995 inclusive) which evaluates patients with cardiac tamponade from a clinical and electrocardiographic, as well as echocardiographic, point of view. MATERIALS AND METHODS: Thirty-nine consecutive patients with cardiac tamponade were evaluated clinically and by ECG and two-dimensional echocardiography, before and after drainage of the pericardial effusion. The drainage was done by pericardiocentesis alone in 28 cases (72%), pericardiocentesis followed by surgery in seven cases (18%) and surgery alone in four cases (10%). MAIN RESULTS: After drainage we observed a reduction in the diameter of the pericardial effusion from 30.1 +/- 8 to 8.1 +/- 7 mm; the occurrence of jugular vein turgescence decreased from 87% to 5% (p < 0.001) and heart rate also decreased from 100 +/- 20 beats/minute to 79 +/- 17 beats/minute (p < 0.001). Systolic blood pressure increased from 107.8 +/- 20.4 mmHg to 134.6 +/- 20.3 mmHg (p < 0.001). All longitudinal and transversal diameters of the cardiac chambers increased after drainage. The greatest increase was observed in the transversal diameters of the right chambers. CONCLUSIONS: Cardiac tamponade affects both right and left cardiac chambers which are affected in their transversal as well as longitudinal diameters; the effect of compression was more marked in the right chambers and in the transversal diameters.

Adolescent↗
PubMed1997

[Therapeutic results: tacrine].

Tacrine is the first drug having been demonstrated as effective for the treatment of mild and moderate forms of Alzheimer's disease. It works as a potent centrally active inhibitor of acetylcholinesterase and therefore has cholinomimetic properties. The authors evaluate the costs/benefits ratio of this drug taking into account clinical and economical data.

Alzheimer Disease↗
PubMed1994

Ribozyme targeting of HIV-1 LTR.

The 5'-TAR region of HIV-1 mRNA is highly conserved amongst different HIV-1 isolates. We thus investigated the potential for in vivo targeting of the TAR RNA element by a hammerhead ribozyme. The use of the CAT reporter gene linked to the HIV1-LTR, in transient assays, reveals that a hammerhead ribozyme directed towards the first GUC of HIV-1 mRNA can efficiently inhibit CAT protein expression. We show that this inhibition is sequence-specific and probably due to a cleavage activity rather than an antisense effect. We show also that a hammerhead ribozyme that is inactive in vitro is capable of inhibiting CAT protein expression in a cellular environment. These results suggest that the targeting of the HIV-1 LTR by a hammerhead ribozyme constitutes a viable approach for anti-HIV therapy.

Base Sequence↗
PubMed1994

Healing of aortic prosthetic grafts: a study by magnetic resonance imaging.

Thirty-six patients with aortoiliac reconstruction were studied by magnetic resonance imaging (MRI) to determine the diameter, baseline signal, and subsequent magnetic signal characteristics of postoperative periprosthetic collection (PPC). Our study confirmed the presence of PCC in most cases (32/36). The diameter was significantly (p < 0.05) correlated with the type of disease being treated, the type of proximal anastomosis created, and whether or not drainage and postoperative transfusion were used. PPC usually disappeared within 3 to 6 months postoperatively. Modifications of magnetic signals T1 and T2 require approximately the same amount of time to diminish. During follow-up investigations in this series, there was one case of prosthetic infection characterized by the persistence of PPC and a strong T2 signal 6 months after surgery, the latter corresponding to incomplete or delayed healing. The MRI aspects of normal healing of aortic grafts were analyzed to correctly interpret the MRI aspects of complications in surgery of the aorta.

Aged↗
PubMed1994

In a changing world: database to keep the pace.

A database to manage health care information can be an especially useful tool for the CNS. Systematic management of information is important in the multifaceted role characteristic of the CNS's scope of practice. The CNS not only provides theoretically sound creative care to patients and serves as a role model to nursing staff, but also monitors and substantiates the quality and effectiveness of care delivered. To do this, the CNS participates in research activities and synthesizes and uses research findings. These aspects of professional practice require collection and analysis of information that could be facilitated by the use of a database. The purposes of this article are to introduce some basic concepts of database and its relevance and contribution to the CNS, discuss issues inherent in setting up a database, and provide guidelines for CNSs who are considering using a database in their clinical practice.

Databases, Factual↗
PubMed1994

[Disorders of neuronal migration: clinical and radiological signs in 21 patients].

We describe 21 patients affected by neuronal migration disorders. The main clinical manifestations were epilepsy, hemiparesis with hemiatrophy and psychomotor retardation. The neuronal migration disorders most frequently diagnosed were various forms of heterotopia and schizencephaly. Magnetic resonance imaging was more sensitive and specific that computed tomography in the diagnosis of these disorders. Schizencephaly correlates well with hemiparesis and hemiatrophy, as does nodular heterotopia with focal epilepsy and diffuse neuronal migration disorders with severe encephalopathies.

Adolescent↗
PubMed1993

Similarity of the 5' and 3'-TAR secondary structures in HIV-1.

The structure of the TAR RNA element transcribed at the 5' end of the R region of the human immunodeficiency virus is compared to the structure of its duplicate sequence in the 3' R region of the viral genome. Based on the 5'-TAR secondary structure already described, we assessed by RNase T1 primer extension assay the degree of similarity between the 5'-TAR and the 3'-TAR RNA secondary structures. We also analysed the influence of modifications in the flanking sequences. We show that the secondary structures of the 5'-TAR and the 3'-TAR are very similar and are not influenced by the flanking sequences.

Base Composition↗
PubMed1993

Activation of HIV-specific ribozyme activity by self-cleavage.

A hammerhead ribozyme designed to cleave in trans the R region of HIV-1 RNA was inserted into a eukaryotic expression vector. This ribozyme was studied in vitro using the T3 RNA polymerase promoter located upstream of the eukaryotic promoter. The ribozyme showed no activity against its specific target sequence under any condition tested. To decrease the influence of potential cis inhibitory sequences in such a ribozyme transcript, a specific target sequence was inserted upstream of the ribozyme-coding sequence. This insertion allowed the release by cis cleavage of a short RNA bearing ribozyme activity and able to cleave in trans an external RNA target. The cis cleavage reaction generated two RNA molecules: the shorter RNA species, which included the catalytic domain, showed a trans cleavage reaction. This self-cleavable ribozyme was active in vitro at 37 degrees C against three distinct HIV-1 transcripts sharing the specific target sequence. Ribozyme activity was thus attained by self-cleavage of the ribozyme-containing sequence from the longer vector transcript.

Base Sequence↗
PubMed1993

Detection of internal carotid artery stenosis. Comparison of 2D-MR angiography, duplex scanning, and arteriography.

The purpose of this study was to compare digital subtraction angiography (DSA) and duplex scanning with 2D-Magnetic Resonance Angiography (MRA) to evaluate the accuracy of MRA in determining carotid stenosis. All three methods were applied to 101 carotid arteries in 51 patients. Diameter stenosis of the internal carotid artery was categorized as follows: 0 to 39%, 40% to 59%, 60% to 94%, 95% to 99%, and occlusion (100%). All images were read in blind fashion by different physicians. DSA is still considered the "gold standard" investigation. In 78 arteries the degree of stenosis according to MRA correlated exactly with that of conventional angiography. In the remaining 23, carotid arteries MRA upgraded the stenosis in 13 and downgraded it in 8. The principal problem is the overestimation of the lesion, which was particularly revealing in lesions of more than 60%. Furthermore to date MRA is not able to evaluate the presence of ulceration. For this reason 2D-MRA alone is not a reliable method for evaluating the presence of carotid artery stenosis.

Angiography, Digital Subtraction↗