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Biomedical subjects

L Maggi

Publications and source records attributed to L Maggi.

At least 55 records · Page 3Linked to original sources
PubMed1996

Modulation of the dissolution profiles from Geomatrix multi-layer matrix tablets containing drugs of different solubility.

A new multi-layer tablet design has recently been proposed for constant drug release: Geomatrix Technology (Jago Pharma, Muttenz, Switzerland). It consists in the application of a drug-free barrier layer on one or both bases of an active core (hydrophilic matrix). The partial coating modulates the core hydration process and reduces the surface area available for drug release. The result is an extended release that draws close to a linear profile. The device was mainly intended for soluble drugs, while an excessive reduction of the release rate may be obtained with drugs of low solubility. In this study a new time-dependent polymeric barrier is proposed to control the release of sparingly soluble drugs. Two different barrier compositions (one swellable and one erodible) are applied on active cores containing drugs of different water solubility, Trapidil, Ketoprofen and Nicardipine hydrochlorides, and the drug dissolution patterns of the different multi-layer devices are compared. During dissolution, the swellable barrier swells and gels, but is not eroded, thus acting as a modulating membrane during the release process. The erodible barrier, instead, is progressively removed by the dissolution medium, exposing in time an increasing extent of the planar surface(s) of the core to interaction with the outer environment and to drug release. Both types of coatings are able to control drug release from the devices: the swellable barrier shows a stronger modulation efficiency and is more suitable to modify the delivery pattern of highly soluble drugs; the erodible barrier shows a time-dependent coating effect that provides better control of the dissolution profile of sparingly soluble drugs.

Biocompatible Materials↗
PubMed1995

Community-acquired pneumonia: is there difference in etiology between hospitalized and out-patients?

Since March 1991 a prospective 1-year study of patients with community-acquired, radiologically verified, pneumonia (CAP) was performed at the Divisione Pneumologica, Ospedali Riuniti Bergamo, and at the Centro Pneumo-Allergologico, Bergamo, Italy. The study included 119 out-patients and 60 in-patients, with a median age of 37.4 and 49.8 years respectively. There were not statistically significant differences between the patients included with respect to the various months. The most common underlying illnesses were: chronic obstructive pulmonary disease (20.7%), diabetes (7.3%) and malignancy (3.4%). We found a quite different etiology of CAP between out- and in-patients. By far the most common etiologic agent in out-patients was Mycoplasma pneumoniae (32.8%), while in in-patients was Legionella pneumophila (11.7%). 5 patients had a double infection. There were no distinctive clinical and radiological features found to be diagnostic for any etiologic agent. Hospital stay averaged 12.1 days. 35% of the patients included in the study were been treated by beta-lactam, often parenterally, nevertheless 88 pathogens of the 100 identified were resistant to this antimicrobial therapy. We believe that there should always be a macrolide, erythromycin or the latest ones such as azythromycin, in the treatment of CAP, owing to their efficiency, ease of use and lower cost.

Adult↗
PubMed1994

Health survey of workers occupationally exposed to cobalt.

The results are presented for a health control program using 236 male workers exposed to a cobalt inhalation risk. The study group consisted of grinders, producers of diamond tools, workers in metallurgical and mechanical industries (where Widia tools are processed and sharpened), and finally formerly exposed workers. All subjects received a clinical examination, the European Community for Coal and Steel questionnaire on respiratory complaints, a chest X-ray, pulmonary function test, electrocardiogram and determination of urinary cobalt; in 91 subjects, the metacholine bronchial provocation test was performed. Three cases of interstitial lung disease were identified. There were no cases with a significant alteration of ventilatory function while 20 cases (16 exposed and four formerly exposed workers) showed a reduced carbon monoxide transfer coefficient (TL,CO,sb/Va).

Bronchial Provocation Tests↗
PubMed1994

Modification of the dissolution behaviour of a water-insoluble drug, naftazone, for zero-order release matrix preparation.

The preparation of hydrophilic matrix tablets able to release naftazone, a water-insoluble drug, into an aqueous medium at a constant rate (zero-order dissolution) is described. Enhancement of dissolution rate of the drug was achieved using cross-linked carmellose sodium, beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin. Hypromellose was used as a water-gelling polymer. Tablets could be prepared that released naftazone at a constant rate over 16 h.

Calorimetry, Differential Scanning↗
PubMed1993

Epidemiologic studies of Escherichia coli diarrheal infections in a low socioeconomic level peri-urban community in Santiago, Chile.

The incidence of diarrhea due to six categories of diarrheogenic Escherichia coli was determined in two pediatric cohorts in a low socioeconomic level community in Santiago, Chile, with access to chlorinated water. An age cross-sectional cohort of 340 children aged birth to 47 months was assembled. A newborn cohort was assembled by enrolling 10-12 newborns monthly for 12 months. Episodes of diarrhea were detected by twice weekly household visits. E. coli from stool cultures of cases and matched controls were hybridized with DNA probes specific for enterotoxigenic, enteroinvasive, enteropathogenic, enterohemorrhagic, enteroaggregative, and diffuse adherence E. coli. Overall, the incidence of diarrhea was low (2.1 episodes/infant/year). Nevertheless, a putative E. coli enteropathogen was found in a large proportion of diarrheal episodes, particularly during the summer. In both cohorts, enterotoxigenic E. coli were important pathogens. Enteropathogenic E. coli were incriminated during the first year of life in the newborn cohort, where they were found significantly more often in cases (p = 0.021) than in controls; beyond this age, isolation rates were similar. In contrast, the relative risk of isolation of diffuse adherence E. coli increased with age in the age cross-sectional cohort, where, overall, the difference in rate of isolation between cases and controls was significant (p = 0.0024). Enteroinvasive and enterohemorrhagic E. coli were isolated infrequently. Enteroaggregative E. coli were encountered equally in cases and controls. Facile transmission of E. coli enteropathogens is occurring in this community despite the availability of potable water.

Case-Control Studies↗
PubMed1993

Press-coated tablets for time-programmed release of drugs.

A new dry-coated device for the release of drug after a programmable period of time is proposed. It is intended to be used mainly in the therapy of those diseases which depend on circadian rhythms. Some core formulations, characterized by different release rates and mechanisms (containing diltiazem hydrochloride or sodium diclofenac as model drugs), were coated by compression with different polymeric barrier layers (press-coated systems). The shell formulations tested contained either gellable or erodible polymers. The dissolution profiles of uncoated cores and press-coated devices were compared. The gellable and/or erodible characteristics (properties) of the barrier formulations were also examined by means of a penetrometer. The coatings prevent drug release from the core until the polymeric shell is completely eroded or swollen. This delay in release start is not influenced by the core composition and depends only on the shell formulation. Except for the time-lag, the release kinetics of the drug contained in the core are not significantly influenced by the presence of the erodible barrier, but can be widely modulated using a swellable polymeric shell.

Circadian Rhythm↗
PubMed1993

Determination of 90Sr in milk by using two inorganic exchangers.

Two inorganic exchangers, consisting of PRTD (partially reduced tin dioxide) and CUCR (normal copper chromate), both prepared and studied by the authors, were investigated for radiochemical isolation and purification of 90Sr from milk samples. A procedure combining the use of both exchangers is reported and is recommended when it is necessary to remove a radiobarium interference. Due to the lack of appropriate samples the procedure was tested using defatted milk spiked with 90Sr and 133Ba.

Animals↗
PubMed1993

Pharmacokinetic studies in healthy volunteers on a new gastroprotective pharmaceutic form of diclofenac.

The pharmacokinetic properties of a new gastroprotective pharmaceutical formulation of diclofenac (CAS 15307-79-6) were investigated in twelve healthy volunteers. In this new form the diclofenac is the nucleus of sequential sucralfate-covered tablets. The experimental design was an open, random, two period balanced cross-over study. All the subjects received a single oral dose of 50 mg diclofenac contained in the new formulation or in the reference enteric-coated tablets. Plasma concentrations of diclofenac were determined at 0.5, 1, 2, 4, 6, and 8 h after drug administration using HPLC method. After administration of a diclofenac-sucralfate association diclofenac was quickly absorbed and the peak plasma concentration (0.773 +/- 0.08 microgram/ml) was achieved in about 1 h. AUC(0-infinity) value was about 1.8 micrograms/ml/h and the mean elimination half-life was 1.20 +/- 0.12 h. The pharmacokinetic profile of diclofenac-sucralfate association is similar to the values reported in previous papers for enteric-coated forms; anyway an early occurrence of the peak plasma concentration was observed for the new formulation. The new diclofenac-sucralfate association shows a different rate of absorption (namely an early and greater peak plasma concentration of diclofenac) and a similar extent of absorption (AUC(0-infinity) being not statistically different) as compared to the reference enteric-coated tablets of 50 mg diclofenac. These results could be related to the delaying and protective effect of sucralfate whose action is different from the one carried by the coat of the enteric-coated tablets.

Adult↗
PubMed1992

Enterohemorrhagic Escherichia coli associated with hemolytic-uremic syndrome in Chilean children.

A clinicoepidemiological study was undertaken to determine if enterohemorrhagic Escherichia coli (EHEC) was associated with hemolytic-uremic syndrome (HUS) in children in Santiago, Valdivia, and Temuco, Chile. Prospective surveillance detected 20 hospitalized cases of HUS in children less than 4 years of age in these cities from March 1988 to March 1989. Each HUS patient was matched (by sex and age) with two control children (hospitalized elective-surgery patients). To detect EHEC, DNA from stool culture isolates of E. coli was detected by hybridization with biotin-labelled DNA probes specific for the EHEC virulence plasmid, Shiga-like toxin I (SLT-I) or SLT-II. Stool cultures from 6 of 20 cases (30%) and from 2 of 38 controls (5.3%) yielded EHEC (P = 0.0158). EHEC isolates from all HUS cases hybridized with the EHEC plasmid probe and with probes for SLT-I or -II (or both). The serogroups of the isolates included O157, O26, and O111. EHEC causes HUS in Chile, and the biotinylated gene probes are practical diagnostic tools for epidemiologic studies.

Bacterial Toxins↗
PubMed1992

New oral system for timing-release of drugs.

Polymeric barriers applied by compression have already been used to control drug release rate from matrix tablets. In this paper, polymeric barrier layers, used to prepare and develop a new device able to release the drug after a programmable period of time, are described. Some matrix core formulations, containing Trapidil or Sodium Diclofenac as a model drug, were dry-coated using either a swellable or an erodible shell. This coating prevents drug release from the core until the polymeric layer is not completely eroded or swollen. The time-lag can be modified by changing the barrier formulation and/or the coating thickness. Also drug release profiles (release rate and kinetics), can be widely modified changing the barrier layer characteristics.

Delayed-Action Preparations↗
PubMed1990

Ion exchange chromatography on a new form of tin dioxide for the isolation of strontium radioisotopes from fission products: an application to milk samples.

An amorphous, partially-reduced tin dioxide, having properties of an inorganic exchanger, was tested for application to fission product separations. Due to the good sorption of both strontium and barium the application of the exchanger to radiostrontium isolation from fission product mixtures is subject to important restrictions. An application to 90Sr determination in milk is proposed.

Animals↗
PubMed1990

Practical and economical method for using biotinylated DNA probes with bacterial colony blots to identify diarrhea-causing Escherichia coli.

A simple and economical method was developed for using biotinylated DNA probes to hybridize with bacterial colonies belonging to the various categories of diarrhea-causing Escherichia coli. Simplification and cost containment were achieved by using Whatman no. 541 filter papers instead of nitrocellulose, by minimizing the concentration of proteinase K (an expensive but necessary reagent used to pretreat the colony blots prior to hybridization with biotin-labeled DNA probes) and by reusing hybridization solution containing labeled probe DNA. After exposing the colony blots to lysing solution and steam, followed by lysozyme (1.5 mg/ml), sucrose (25%), and proteinase K (10 micrograms/ml) treatments, biotinylated probes were used to detect enterotoxigenic, enteropathogenic, enterohemorrhagic, diffuse adherence, and enteroinvasive categories of diarrhea-causing E. coli with a high level of sensitivity and specificity. Three independent observers who were experienced in reading DNA blots recorded remarkably similar results, while less satisfactory results were obtained when the blots were read by an inexperienced observer. This technique will be useful in laboratories in which radioactive isotopes are unavailable or impractical and in which budgets are restricted.

Biotin↗
PubMed1990

[Tuberculosis in Bergamo Province. Statistical estimates for the quadrennium 1984-1987].

The clinical files of patients admitted to the Ospedali Riuniti of Bergamo between January 1984 and December 1987 in which the presence of mycobacteria has been demonstrated have been reviewed. We have analysed the clinical pattern and the complicating diseases and we have reported the typing of mycobacteria in comparison with the literature data. We stress the danger of mycobacterial infections particularly in patients who are in an immunodepressed state.

Age Factors↗
PubMed1989

Correlation with age and sex of flash-evoked electroretinogram and retinal oscillatory potentials recorded with skin electrodes.

Electroretinograms and retinal oscillatory potentials to full-field flash stimulation were recorded by dermal electrodes in a population of subjects (1 to 84 yrs) balanced for age and sex (119 females, 133 males), without evidence or history of ocular and/or relevant systemic diseases. The electroretinogram latencies and b-wave amplitude increased, while the a-wave amplitude decreased linearly with age. The oscillatory potential amplitude initially increased, to decrease approximately at the age of 50, with an inverted U-shaped distribution.

Adolescent↗
PubMed1989

[Evaluation of beta cell function in non-insulin-dependent diabetes mellitus (NIDDM) and its correlations with clinico-metabolic parameters].

Authors studied plasma C-peptide in basal period and after stimulation with one mg of glucagon intravenous in 73 patients with NIDDM. The results have confirmed initial clinical diagnosis of NIDDM. Significative correlations were obtained between basal C-peptide and C-peptide response to glucagon (r = 0.861; p less than 0.01); delta C-peptide (difference between C-peptide basal and after response to glucagon) (r = 0.361; p less than 0.01); body mass index (r = 0.423; p less than 0.01). The significant correlations between basal C-peptide, C-peptide response to glucagon and delta C-peptide show that basal C-peptide measurement is a sufficient test for beta-cell secretory capacity, even though do not give indicative signs for therapy choice of NIDDM for its multifactorial pathogenesis.

Adult↗
PubMed1988

Effects of intravenous L-acetylcarnitine on retinal oscillatory potentials.

L-acetylcarnitine is a compound with cholinergic properties and putative action on the visual system and the glucose metabolism. Ten healthy, emmertropic volunteers (age range: 21 to 28 years) were studied. Each subject was administered 5, 10, and 30 mg/kg acute intravenous doses of L-acetylcarnitine and matching placebo. Retinal oscillatory potentials to full-field flash stimulation were recorded before and 30, 60, and 120 min after administration. A systematic reduction of the implicit time of the P2 and N2 oscillatory potential components was observed after administration of the 10 and 30 mg/kg doses: significant changes were not evident at the 5 mg dose or after placebo. The latency reduction was significantly correlated with the postdrug increment of the L-acetylcarnitine plasma concentration. No other systematic modification in latency of amplitude was observed.

Acetylcarnitine↗