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Biomedical subjects

M De Rosa

Publications and source records attributed to M De Rosa.

At least 19 recordsLinked to original sources
PubMed2006

Canard orbits in Fabry-Perot cavities induced by radiation pressure and photothermal effects.

A theoretical study of a high-finesse Fabry-Perot cavity considering radiation pressure and photothermal displacement is reported. We show that the competition between these two effects induces a different kind of dynamic behavior in such a system, consisting of canard orbits and excitability. The transition between the excitable regime and the canard oscillations, occurring through a supercritical Hopf bifurcation, appears in an order compatible with the van der Pol-FitzHugh-Nagumo equations. Besides its interest as a study of general nonlinear dynamics, the characterization of the effects described is critical for high sensitivity interferometric displacement measurements as those employed for gravitational waves detection.

Journal Article↗
PubMed2006

Exopolysaccharides production in Lactobacillus bulgaricus and Lactobacillus casei exploiting microfiltration.

The physiology of Lactobacillus delbrueckii ssp. bulgaricus and Lactobacillus casei, extensively used in the dairy industry, was studied in order to evaluate key parameters in the synthesis of exopolysaccharides and to improve their production through novel fermentation processes. Selected strains were studied in shake flasks and in fermentor experiments using glucose and lactose as main carbon sources and bacto casitone as the only complex component, in a temperature range between 35 and 42 degrees C. The production of exopolysaccharides was monitored and correlated to the growth conditions using both a colorimetric assay and chromatographic methods. Fermentor experiments in batch mode yielded 100 mg l(-1) of EPS from L. bulgaricus and 350 mg l(-1) from L. casei. Moreover, the use of a microfiltration (MF) bioreactor resulted in exopolysaccharides (EPS) concentrations threefold and sixfold those of batch experiments, respectively. The monosaccharidic composition of the two analyzed polymers differed from those previously reported. The optimization of the production of EPSs using the MF fermentation strategy could permit the use of these molecules produced by generally recognised as safe (GRAS) microorganisms in the place of other polysaccharides in the food industry.

Bioreactors↗
PubMed2005

Upper limits on gravitational-wave emission in association with the 27 Dec 2004 giant flare of SGR1806-20.

At the time when the giant flare of SGR1806-20 occurred, the AURIGA "bar" gravitational-wave (GW) detector was on the air with a noise performance close to stationary Gaussian. This allows us to set relevant upper limits, at a number of frequencies in the vicinities of 900 Hz, on the amplitude of the damped GW wave trains, which, according to current models, could have been emitted, due to the excitation of normal modes of the star associated with the peak in x-ray luminosity.

Journal Article↗
PubMed2005

Prevalence and incidence of antibodies to Borrelia burgdorferi and to tick-borne encephalitis virus in agricultural and forestry workers from Tuscany, Italy.

The ticks Ixodes persulcatus and Ixodes ricinus are the main vectors of both Borrelia burgdorferi sensu lato and tick-borne encephalitis (TBE) virus in Eurasia. Borrelia burgdorferi is the cause of Lyme borreliosis, and TBE is a biphasic meningoencephalitis induced by an arbovirus belonging to the flavivirus family. The principal aims of the current investigation were (i) to determine the frequency of serological evidence of Borrelia burgdorferi sensu lato and TBE infections in healthy agricultural and forestry workers, (ii) to determine the incidence of seroconversion for antibodies against Borrelia burgdorferi sensu lato and TBE virus in Tuscan workers during a 1-year survey; and (iii) to assess the occupational risk for agricultural and forestry activities in a defined area (Tuscany, Italy). A total of 412 blood samples were taken from agricultural and forestry workers, and information on age, duration of employment, and history of tick bites was collected in a questionnaire to establish the risk factors for the diseases. Three hundred sixty-five blood donors from the same region served as controls. To estimate the rate of seroconversion, 176 of the agricultural and forestry workers were tested 1 year later. IgG and IgM antibodies against Borrelia burgdorferi sensu lato and TBE virus were detected in serum by an enzyme-linked immunosorbent assay and confirmed by Western blot analysis for Borrelia burgdorferi and by a test for inhibition of hemagglutination for TBE. Antibodies against Borrelia burgdorferi were more frequent among the workers than in the control group (7.8% vs. 4.9% in the IgG-IgM enzyme-linked immunosorbent assay and 7.03% vs. 3.56% in the confirmatory test). No seropositivity was observed for TBE virus. Eighteen of 176 subjects who underwent a second blood test developed specific antibodies against Borrelia burgdorferi within 1 year.

Adult↗
PubMed2004

Expression of Sulfolobus solfataricus alpha-glucosidase in Lactococcus lactis.

The industrial potential to use extreme thermophilic microorganisms and their enzymes lies in applications in which the temperature cannot be adjusted (cooled) at will. The production of enzymes from wild-type thermophiles is very low, therefore, for industrial applications, it is necessary to use recombinant microorganisms. In this paper, the cloning of a heat-stable alpha-glucosidase from Sulfolobus solfataricus using lactic acid bacteria as expression system is reported. The extremophilic alpha-glucosidase was cloned in Lactococcus lactis and correctly folded despite being expressed at a lower temperature. The recombinant cells were assayed for enzyme residual activity at 75 degrees C in order to analyze the direct use of whole cells as biocatalysts. Maximum activity corresponded to 40 U/l in static cultures. The protein yield was further improved by optimizing fermentation and reached 600 U/l in batch mode. Microfiltration led to an even higher enzyme production of 850 U/l as a result of increased biomass. The overall production of alpha-glucosidase using the engineered L. lactis strain in microfiltration fermentation is 1,000-fold higher than obtained using the wild-type.

Cloning, Molecular↗
PubMed2004

Er:YAG laser treatments on dentine surface: micro-Raman spectroscopy and SEM analysis.

OBJECTIVE: This study aims to give an insight into the chemical and structural modifications occurring in laser treated dentine surface, as a tool to plan a new class of dental materials specific for the dental restoration when laser technologies are used. For this purpose the effect of Er:YAG (Erbium-Yttrium Aluminium Garnet) laser treatments on human dentine surface has been investigated. METHODS: The dentine surface of periodontally compromised teeth cut along the main axis was treated in vitro with laser pulses having the same energy but time duration varying in the range of 100-1000 micros. The chemical characteristics and the morphology of the laser treated surface have been studied with micro-Raman spectroscopy (micro-RS) and scansion electron microscopy (SEM). RESULTS: The micro-RS and SEM analysis of laser treated teeth have been compared with those of surfaces treated with conventional mechanical methodologies. The laser pulse time duration affects the surface morphology and the chemistry of dentine, mainly of organic components. The effects have been monitored by analysing the C-H group stretch vibration mode of the micro-RS spectrum. CONCLUSION: The laser treatment can determine different chemical microenvironments on the treated dentine surface, depending on the time duration of laser pulse used. Treatments with very long pulse results in a the dentine surface very similar to that obtained with a conventional mechanical drill, while with very short laser pulses a strong modification of the dentine organic components has been observed.

Aluminum Silicates↗
PubMed2004

Signal processing and calibration procedures for in situ diode-laser absorption spectroscopy.

Gas analyzers based on tunable diode-laser spectroscopy (TDLS) provide high sensitivity, fast response and highly specific in situ measurements of several atmospheric trace gases simultaneously. Under optimum conditions even a shot noise limited performance can be obtained. For field applications outside the laboratory practical limitations are important. At ambient mixing ratios below a few parts-per-billion spectrometers become more and more sensitive towards noise, interference, drift effects and background changes associated with low level signals. It is the purpose of this review to address some of the problems which are encountered at these low levels and to describe a signal processing strategy for trace gas monitoring and a concept for in situ system calibration applicable for tunable diode-laser spectroscopy. To meet the requirement of quality assurance for field measurements and monitoring applications, procedures to check the linearity according to International Standard Organization regulations are described and some measurements of calibration functions are presented and discussed.

Air Pollutants↗
PubMed2004

Fourteen-year experience with imported malaria.

Geographical position, an increasing flow of immigrants and refugees coming from regions where malaria is endemic might further increase those cases of malaria imported to Calabria due to travel on military missions, visiting relatives, business and leisure. However, few reports have been published regarding malaria imported into the southern Italian region of Calabria. Based on data from our laboratory, official reports received from the Italian Ministry of Health and Regional Health Offices, an epidemiological analysis of malaria cases registered in Calabria from January 1988 to December 2001 is reported. The epidemiological and clinical features concerning the cases are discussed. A total of 34 slide-confirmed malaria cases were observed in Calabria during the period in question. Infections were mostly acquired in Africa (84.8%), while remaining infections came from Asia (9.1%) and South America and Europe (6.0%). Length of stay in the endemic area did not increase the infection risk. Etiological diagnosis indicated Plasmodium falciparum as the species most often involved (60.6%), followed by Plasmodium vivax (36.3%) and P. vivax/Plasmodium malariae mixed infection (3.0%). The mortality rate was about 3.0%. The number of cases during the second seven-year period of this study was almost double that of the first seven-year period. Correct chemoprophylaxis was performed by only 27.3% of our studied subjects. Delay of malaria diagnosis ranged between 4 days and 1 month. In conclusion, increases in malaria cases, mostly due to P. falciparum, delay in diagnosis and reporting to the Regional Health Office, as well as the increasing arrival of refugees from endemic areas, are epidemiological concerns in Calabria, the southernmost region of continental Italy.

Adult↗
PubMed2002

Experimental measurement of the dynamic photothermal effect in Fabry-Perot cavities for gravitational wave detectors.

We report the experimental observation of the frequency dependence of the photothermal effect. The measurements are performed by modulating the laser power absorbed by the mirrors of two high-finesse Fabry-Perot cavities. The results are very well described by a recently proposed theoretical model [M. Cerdonio, L. Conti, A. Heidmann, and M. Pinard, Phys. Rev. D 63, 082003 (2001)]], confirming the correctness of such calculations. Our observations and quantitative characterization of the dynamic photothermal effect demonstrate its critical importance for interferometric displacement measurements towards the quantum limit, as those necessary for gravitational wave detection.

Journal Article↗
PubMed2002

A novel thermophilic fusion enzyme for trehalose production.

In recent years a number of hyperthermophilic micro-organisms of Sulfolobales have been found to produce trehalose from starch and dextrins. In our laboratory genes encoding the trehalosyl dextrin forming enzyme (TDFE) and the trehalose forming enzyme (TFE) of S. solfataricus MT4 have been cloned and expressed in E. coli (Rb791). Here we report the construction of a new protein obtained by fusion of TFE and TDFE coding sequences which is able to produce trehalose from dextrins at high temperature by sequential enzymatic steps. We demonstrate that the bifunctional fusion enzyme is able to produce trehalose starting from malto-oligosaccharides at 75 degrees C. Furthermore we partially purified the recombinant fusion protein from bacterial cell free extracts and from insoluble fractions in which the fusion protein was also found as aggregate in inclusion bodies.

Bacterial Proteins↗
PubMed2002

Glutathione peroxidase (GPX) activity in seminal plasma of healthy and infertile males.

Human spermatozoa are more dependent on glutathione peroxidase/glutathione reductase (GPX/GR) system, via reduced glutathione (GSH), to inactivate reactive oxygen metabolites (ROMs) such as hydrogen peroxide and organic hydroperoxides. To demonstrate whether there is a substantial difference in GPX activity between normal and pathological seminal plasma, we decided to evaluate the activity of this enzyme in healthy subjects and infertile males with normal hormonal patterns. Our results demonstrate that in healthy subjects the seminal plasma contains a GPX activity that is about 10 times greater than the GPX activity detected in the seminal plasma of infertile males. By using specific antibodies against plasmatic GPX (GPX3), we also demonstrate that enzymatic activity, detected in the seminal plasma of both healthy and infertile males is GPX3. Therefore, the evaluation of GPX activity in human seminal plasma could be a new useful marker of gonadal function in men.

Adult↗
PubMed2002

Short-term suppression of GH and IGF-I levels improves gonadal function and sperm parameters in men with acromegaly.

Experimental data support a role for GH and IGF-I in the reproductive process in humans, but the effect of chronic GH excess on gonadal and reproductive function in men has been never investigated. To understand the effects of short-term GH and IGF-I suppression on the gonadal axis and seminal fluid characteristics in men with acromegaly, we evaluated 35 patients (age 27-59 yr) with active disease and 35 age-matched healthy controls. Gonadal hormones and seminal fluid analysis were evaluated before and 6 months after surgery or lanreotide (LAN) (60 mg/month). At study entry, FSH, testosterone (T), and dihydrotestosterone (DHT) (P < 0.0001) levels, seminal volume, sperm count, total motility and forward progression, normal morphology, and vitality were significantly lower in patients with acromegaly than in controls. After 6 months, 22 patients achieved disease control after surgery (n = 11) or LAN (n = 11), whereas 13 had uncontrolled disease. Serum T and DHT levels and sperm number significantly increased in all groups. FSH and LH levels and total motility increased only in patients achieving disease control. Posttreatment IGF-I levels significantly correlated with total motility (r = -0.45; P = 0.006). In conclusion, short-term GH and IGF-I suppression after surgery or LAN significantly increased T and DHT levels and improved sperm number and motility in acromegalic men.

Acromegaly↗
PubMed2001

S-adenosyl-L-methionine N-ole-1-oyltaurate: pharmacokinetic of the orally administered salt in rats.

A pharmacokinetic study based on the distribution of radioactivity from the double labelled S-adenosyl-L-methionine (SAM) has been carried out by oral administration of the liposoluble stable salt [methyl-(14)C, 8-(3)H]SAM N-ole-1-oyltaurate to rats. The SAM sulfate p-toluensulfonate salt, the only SAM salt at present commercialized as drug, was chosen as reference compound to have a comparative pharmacokinetic analysis. The metabolism of the SAM is characterised by a differential use of the two labelled moieties by the various organs, liver being the most active in metabolizing the sulfonium compound with a preferential uptake of the methyl-(14)C fragment. The radioactivity detected after the administration of [methyl-(14)C, 8-(3)H]SAM N-ole-1-oyltaurate is, in all the organs examined, two times higher than the [methyl-(14)C, 8-(3)H]SAM sulfate p-toluensulfonate compound, attesting that the liposoluble [methyl-(14)C, 8-(3)H]SAM N-ole-1-oyltaurate is provided with better bioavailability.

Administration, Oral↗
PubMed2001

Estrogens and health in males.

Estrogen receptor concentrations are higher in the male reproductive tract than in other organs. Brain structure, neuronal organization and behavioral sex differences result from brain conversion of testosterone into estradiol within the brain. Estrogens modulate hormonal secretion at pituitary level and immune function at thymus level. Estrogens promote vasodilatatory and protective effects on the cardiovascular system by acting on the vascular smooth muscle and endothelium. Adult men with mutations in genes for estrogen receptor or aromatase are affected by osteopenia and tall stature, open epiphysis, which is corrected by estrogen treatment. Over the past few years there has seen a decline in sperm concentration, which has been attributed to exposure of fetal testes to estrogens. Many substances have estrogen-like properties and inhibit the action of estradiol or testosterone action. In conclusion, estrogens play a pivotal role in men also. In particular, taking in account their prevalent origin from testosterone aromatization at tissue and peripheral levels the presence and the distribution of the two receptors (ERalpha and ERbeta) are responsible for different responses in physiological and pathological conditions.

Adult↗
PubMed2001

Bone mineral density and bone markers in hypogonadotropic and hypergonadotropic hypogonadal men after prolonged testosterone treatment.

After prolonged treatment (76.4+/-10 and 70.1+/-12.3 months, respectively) (mean+/-SE) with testosterone enanthate (250 mg i.m. every 3 weeks), bone mineral density (BMD) and bone metabolism were evaluated in 12 patients (aged 29.3+/-1.4 yr) affected by idiopathic hypogonadotropic hypogonadism (IHH), in 8 patients (29.6+/-2.6 yr) affected by Klinefelter's syndrome (KS), and in 10 healthy men (30.6+/-1.7 yr) matched according to age and BMI. Spinal BMD in IHH was significantly lower than in controls (0.804+/-0.04 vs 1.080+/-0.01 g/cm2; p<0.001), while there was no difference in neck BMD (0.850+/-0.01 vs 0.948+/-0.02 g/cm2). Neither spinal (0.978+/-0.05 g/cm2) nor neck (0.892+/-0.03 g/cm2) BMD in KS were significantly different from controls. Six IHH and one KS subjects were osteoporotic, while 6 IHH and 2 KS subjects were osteopenic. A significant inverse correlation was found between spinal BMD and age at the treatment onset in IHH (r=-0.726, p=0.007). In IHH there were significant increases in bone formation (alkaline phosphatase=318.3+/-33.9 vs 205.4+/-20.0 IU/l; osteocalcin=13.44+/-1.44 vs 8.57+/-0.94 ng/ml; p<0.05) and in bone resorption (urinary cross-linked N-telopeptides of type I collagen=149.1+/-32.3 vs 47.07+/-8.4 nmol bone collagen equivalents/mmol creatinine; p<0.05) compared to controls, while such differences were not present in KS. Our results outline the importance of BMD evaluation in all hypogonadal males. Nevertheless, bone loss is a minor characteristic of KS, while it is a distinctive feature of IHH. Therefore, early diagnosis and age-related replacement therapy coupled with a specific treatment for osteoporosis could be useful in preventing future severe bone loss and associated skeletal morbidity.

Adult↗
PubMed2000

Effective production of a thermostable alpha-glucosidase from Sulfolobus solfataricus in Escherichia coli exploiting a microfiltration bioreactor.

A microfiltration (MF) membrane bioreactor was developed for an efficient production of a recombinant thermostable alpha-glucosidase (rSsGA) from Sulfolobus solfataricus MT-4. The aim of the membrane bioreactor was to improve the control of the concentration of key components in the growth of genetic engineered microorganisms, such as Escherichia coli. The influence of medium composition was studied in relation to cell growth and alpha-glucosidase production. The addition of components such as yeast extract and tryptone resulted in a higher enzyme production. High cell density cultivation of E. coli BL21(DE3) on semidefined medium, exploiting a microfiltration bioreactor, was studied in order to optimize rSsGA production. In addition to medium composition, the inducer employed (either isopropyl beta-D-thiogalactopyranoside or lactose), the induction duration, and the cultivation mode influenced both the final biomass and the enzyme yield. The MF bioreactor allowed a cell concentration of 50 g/L dry weight and a corresponding alpha-glucosidase production of 11,500 U/L. The improvement obtained in the enzyme production combining genetic engineering and the microfiltration strategy was estimated to be 2,000-fold the wild-type strain.

Bioreactors↗