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Biomedical subjects

S Michelini

Publications and source records attributed to S Michelini.

At least 19 recordsLinked to original sources
PubMed2000

Polymers with pH-dependent solubility: possibility of use in the formulation of gastroresistant and controlled-release matrix tablets.

Polymers usually utilized for gastroresistant film coating of tablets or pellets such as cellulose acetate phthalate (CAP), cellulose acetate trimellitate (CAT), hydroxypropylmethylcellulose phthalate (HPMCP), and Eudragit L and S were used in the preparation of drug/polymer matrix tablets. These tablets were prepared either by direct compression of both powders or by the formulation of microspheres that were then compressed. The microspheres were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry analyses. Dissolution studies were finally carried out to verify if the tablets possessed gastroresistant or controlled-release characteristics. Except for Eudragit L, the polymers can be used under certain conditions in the formulation of modified-release tablets.

Acetaminophen↗
PubMed1997

The panic-agoraphobic spectrum: a descriptive approach to the assessment and treatment of subtle symptoms.

OBJECTIVE: Psychiatric classification is still a topic of considerable discussion and debate in spite of major advances in the past two decades. The debate involves categorical versus dimensional approaches, cutoff numbers of symptoms to define a case, degree of impairment, objective diagnostic criteria versus more theoretically based criteria, episodic versus trait-like symptoms, and the role of atypical and subclinical symptoms. All of these issues have been raised for the anxiety disorders and depression. This article presents the conceptualization of a relatively novel and testable approach to the diagnosis and classification of panic and agoraphobia, the panic-agoraphobic spectrum, and pilot data on a new questionnaire to assess it. METHOD: Pilot testing of the Panic-Agoraphobic Spectrum Questionnaire was undertaken with 100 inpatients who had lifetime diagnoses of panic disorder, unipolar depression, comorbid panic and unipolar depressive disorders, or an eating disorder. The instrument emphasizes impairment related to 144 behaviors and experiences in seven panic-agoraphobic symptom domains. RESULTS: Patients with panic disorder scored highest on the questionnaire, and those with comorbid depression showed even greater severity of illness. The scores of the patients with eating disorders and of the depressed patients differed from those of the other groups but also differed from 0. CONCLUSIONS: The spectrum model of panic and agoraphobia is a flexible and comprehensive means of describing this clinical complex. The proposed model, complementary to the categorical approach, presumably expresses a unitary pathophysiology. Its usefulness is discussed in terms of its value for patient-therapist communication, outcome measures, identification of subtle personality traits, and subtyping of patients for research and treatment.

Adult↗
PubMed1996

Circulating levels of anticonvulsant metabolites of progesterone in women with partial epilepsy in the intercritical phase.

The 3alpha-hydroxy metabolites of progesterone (P), 3alpha-hydroxy-5alpha-pregnan-20-one (allopregnanolone, A-PREG) and 3alpha-hydroxy-5beta-pregnan-20-one (pregnanolone, PREG), have been found to be among the most potent ligands of gamma-aminobutyric (GABA)-A receptors; in experimental animals, they have been found to have anxiolytic, hypnotic and anticonvulsant effects. Similar to those of the benzodiazepines and barbiturates that interact with GABA-A receptors. The present study was undertaken to determine plasma A-PREG and PREG concentrations in the luteal phase in women with partial epilepsy, in order to determine if an impaired metabolism of P occurs in this convulsive disorder. We measured plasma P, A-PREG and PREG levels in 15 women with partial epilepsy in the intercritical phase, and in 15 age-matched healthy women, during the luteal phase of the ovarian cycle (22nd-24th day). The mean plasma +/- S.E. A-PREG levels (three blood samples) were 0.7 +/- 0.6 ng/ml in the epileptic women and 0.5 +/- 0.2 ng/ml in controls, with no significant difference between the two groups (p = NS); the PREG levels were also similar (1.4 +/- 1 ng/ml and 1 +/- 1.1 ng/ml, respectively: p = NS). A significant correlation was found between P levels and both A-PREG and PREG levels (r = 0.72, p < 0.001 and r = 0.79, p < 0.001, respectively). There were no significant differences between the two groups in terms of serum adrenocorticotropic hormone, cortisol, dihydroepiandrosterone-sulfate, follicle stimulating hormone, prolactin, luteinizing hormone or estradiol levels.

Adolescent↗
PubMed1996

Identification of a Ser857-Asn857 substitution in DRK1 (KCNB1), population frequencies and lack of association to the low voltage alpha EEG trait.

A nonconservative amino acid substitution (Ser857Asn) in the human delayed-rectifier potassium channel DRK1 (KCNB1 locus), a candidate gene for the low voltage alpha electroencephalogram (EEG) trait locus (LVEEG1) at 20q13.2, and its frequency in ethnic population samples are described. The frequency of Asn857 in seven different ethnic population samples, totalling more than 1600 individuals, ranged from zero to greater than 3%. However, no association was found between Asn857 and the low voltage alpha EEG trait (LVA) in a population of 105 subjects assessed for the EEG, 24 of whom actually had LVA.

Alleles↗
PubMed1996

Long-term use of benzodiazepines: tolerance, dependence and clinical problems in anxiety and mood disorders.

This paper reviews the literature on the epidemiological, biological and clinical features of benzodiazepine dependence and withdrawal syndrome, focusing on clinical problems associated with the long-term use of benzodiazepine (BZs) in mood and anxiety disorders. These conditions represent the most frequent mental disorders for which BZs are overprescribed. In addition to dependence and withdrawal phenomena, the presence of chronic subtle toxicity and the interference with the underlying psychopathology observed with BZ use suggests a need for a more careful evaluation of the risk-benefit ratio in the long-term administration of BZs.

Anxiety Disorders↗
PubMed1995

Polymorphism and genetic mapping of the human oxytocin receptor gene on chromosome 3.

Centrally administered oxytocin has been reported to facilitate affiliative and social behaviours, in functional harmony with its well-known peripheral effects on uterine contraction and milk ejection. The biological effects of oxytocin could be perturbed by mutations occurring in the sequence of the oxytocin receptor gene, and it would be of interest to establish the position of this gene on the human linkage map. Therefore we identified a polymorphism at the human oxytocin receptor gene. A portion of the 3' untranslated region containing a 30 bp CA repeat was amplified by polymerase chain reaction (PCR), revealing a polymorphism with two alleles occurring with frequencies of 0.77 and 0.23 in a sample of Caucasian CEPH parents (n = 70). The CA repeat polymorphism we detected was used to map the the human oxytocin receptor to chromosome 3p25-3p26, in a region which contains several important genes, including loci for Von Hippel-Lindau disease (VHL) and renal cell carcinoma.

Alleles↗
PubMed1991

[Benzodiazepine withdrawal syndrome. Problems of differential diagnosis against depression, panic attacks and generalized anxiety].

Anxiety and mood disorders are among the psychic afflictions which tend to lead to prolonged benzodiazepine intake. This is also one of the reasons why doctors are faced with a difficult task when having to differentiate between these phenomena and the anxiolytic withdrawal syndrome. Since preexisting psychiatric pathology may modify withdrawal symptoms, thus making differential diagnosis between withdrawal syndrome and recrudescence of the previous disorder even more difficult, it is necessary carefully to assess clinical phenomenology both in relation to its course and to its variability with possible emergence of new symptoms. In addition to drawing attention to the diagnostic elements that can be most useful for identifying the withdrawal syndrome in mood disturbances and panic attack disorder, the authors also report the data of an experimental study of benzodiazepine withdrawal in patients suffering from generalized anxiety.

Anxiety↗
PubMed1991

[Benzodiazepine withdrawal syndrome].

Benzodiazepines (BDZ) are widely prescribed in clinical practice for many pathological conditions, because of their anxiolytic, sedative, myorelaxant and anticonvulsant properties. The effectiveness, specificity and rapidity of action, the few side effects and the virtual absence of toxicity, have contributed to the widespread use of these compounds. In the last decade, however, the attitude towards BDZ has greatly changed, due to growing awareness and concern about dependence liability, withdrawal phenomena, and long-term side effects. Withdrawal symptoms have been singled out and specified in the contest of a well-defined syndrome with foreseeable onset, duration and remission. Psychic and physical symptoms and disorders of sensory perception can be observed. These manifestations can be suppressed by resuming treatment. The symptomatic and developmental aspects of BDZ withdrawal syndrome are discussed, according to the available literature, with particular reference to clinical features of patients suffering from anxiety and mood disorders.

Anti-Anxiety Agents↗
PubMed1991

[Omega benzodiazepine receptor subtypes and new ligands].

Pharmacological and biochemical studies indicate that for many receptors, distinct subtypes exist; the multiplicity and diversity of signal reception proteins increase the information-handling capacity of neurons, thus contributing to neural plasticity. This is also the case for the allosteric modulatory-centre omega of the GABA-A receptor. Binding studies suggest the presence of at least two pharmacologically distinct omega receptors in the human brain; furthermore, molecular biological studies have confirmed the existence of genes encoding different omega subtypes. As omega receptors are the site of action of benzodiazepines and other anxiolytic compounds, this knowledge may be useful for developing new subtype-specific drugs, with more selective therapeutic effects.

Anti-Anxiety Agents↗
PubMed1990

Stress-related changes of benzodiazepine binding inhibitory activity (B.B.I.A.) in humans.

The presence of benzodiazepine binding inhibitory activity (B.B.I.A.) in sera from 44 psychiatric patients and from 14 healthy volunteers, prompted us to investigate whether or not this activity underwent changes in stressful situations. We measured the inhibitory units (IU) of deproteinized sera of 12 subjects, immediately before and 2 weeks after sitting for a difficult university exam. Our results showed significantly higher IU values (i.e., higher B.B.I.A. concentrations) in the samples taken just before the exam. This preliminary finding clearly suggests the involvement of B.B.I.A. in anxiety mechanisms.

Adult↗
PubMed1989

Further investigation on benzodiazepine binding inhibitory activity in patients with major depression or panic disorder and in healthy volunteers.

Preliminary findings regarding the presence of plasmatic benzodiazepine binding inhibitory activity (BBIA) in 14 psychiatric patients prompted us to investigate it further in larger samples of psychiatric patients (n = 44) and in healthy controls (n = 14). The results have shown that BBIA is present in all the subjects included with statistically significant differences between the patients and controls. The highest concentrations were found in the patients with no difference between anxious or depressed patients, and the lowest in the healthy controls. These findings indicate that BBIA might play a role in the pathophysiology of some manifestations of anxiety.

Adult↗
PubMed1984

Simultaneous recording of auditory evoked potentials. Relationships among the fast, middle and long latency components.

The whole pattern of the fast, middle and long latency auditory evoked potentials (AEP) was recorded simultaneously from the scalp surface of 13 normal-hearing adults. The individual responses were displayed on a nonlinear time axis in order to improve identification of the components. Stimulation consisted of 2048 unfiltered clicks, delivered monaurally at 80, 60, 40 dB HL with an ISI of 750 ms. Changes in mean latency and amplitude of each AEP component were statistically evaluated in relation to intensity and electrode montage (vertex-mastoid ipsi- and contralateral to the stimulated ear). The latencies of fast components I-VI and the slow P1 increase significantly with declining stimulus intensity. The amplitudes of the fast, I, II, III, V and the slow P1-N1, P2-N2 decrease significantly with intensity. As regards differences due to the electrode montage the contralateral recording causes significant changes in latency of the fast potentials up to wave IV, and changes in amplitude of the fast up to wave V, and of the slow P1-N1 and P2-N2. Therefore, as their latency and amplitude seem to be less closely related to the stimulus and electrode placement, the middle components behave differently, compared with the preceding and following components. Based on parametric comparisons of potentials ranging widely in latency, but each one evoked by an equal sensory input, this kind of AEP evaluation may be useful both for neurophysiological and clinical studies of the whole auditory pathway function.

Adult↗