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L Martini

Publications and source records attributed to L Martini.

At least 37 records · Page 2Linked to original sources
PubMed2003

Hospital infection control in Italy.

In 1998, the National Health Plan identified the reduction of hospital infection (HI) incidence as a priority. This article reviews the main activities set up in Italy on infection control in the hospital setting. In 1983, the first national prevalence survey reported 6.8% and 7.6% prevalence rates of patients with HI and of HIs, respectively. The high point prevalence found in the intensive care units (ICU) (12.5%), prompted a national incidence study in 1985. This study found an incidence of 29.5 HIs per 100 patients in the ICUs: lower respiratory tract infections (LRTI) were the most common HIs (47.8%), followed by urinary tract infections (UTI) (19.9%) and blood stream infections (BSI) (4.8%). A 1999 survey showed that in 463 Italian hospitals only 40.5% had protocols on the use of disinfectants, 32.3% on sterilization, 30.8% on occupational risk management, 18.3% on isolation measures, 17.7% on hand-washing, 14.3% on antibiotic prophylaxis in surgery, 9.4% on the prevention of surgical site infections and 8.5% on the management of CVC. A national forum to consider surveillance systems using standardized definitions and methodologies is urgently needed.

Bacteremia↗
PubMed2003

Prevalence of nosocomial infections in 15 Italian hospitals: first point prevalance study for the INF-NOS project.

BACKGROUND: The aim of our study was to assess the magnitude of nosocomial infections (NI) in 15 Italian hospitals. PATIENTS AND METHODS: A multicenter point prevalence study of NI was carried out in October 2001 among eight medical, surgical and intensive care units in hospitals with more than 400 beds, after a pilot phase performed in April 2001. RESULTS: Of the 2,165 surveyed patients, 163 had a total of 179 NIs. The global prevalence rate of patients with NI and of NI was respectively 7.5% (95% CI 6.4-8.6) and 8.3% (95% CI 7.1-9.4), ranging from 5.5% (95% CI 4.2-6.8) in medical wards to 34.2% (95% CI 25.7-42.7) in intensive care units (ICUs). The NI prevalence was higher in: hospitals that did not have an infection control committee (ICC) compared to hospitals with an ICC (10.3%, 95% CI 6.4-10.1 versus 7.2, 95% CI 6.0-8.3, p = 0.08); university hospitals compared with non-teaching hospitals (9.4%, 95% CI 4.5-14.2 versus 7.4%, 95% CI 6.3-8.5, p = 0.4) and; hospitals with 1,000 or more beds compared to lower volume hospitals (9.5%, 95% CI 7.3-11.7 versus 6.6%, 95% CI 5.3-7.8, p = 0.02). The most prevalent infections found were lower respiratory tract infections, urinary tract infections and surgical-site infections, representing 38.0%, 20.1% and 12.8%, respectively, of all NI. Among 1,674 patients without any infection, 575 (34.3%) of them had been undergoing antibiotic treatment at the time of the survey. CONCLUSION: The high rate of NI, particularly in ICUs, and the high number of improper procedures emphasize the need to develop clinically-oriented guidelines, tailor active infection control programs and implement an active ICU surveillance system.

Bacteremia↗
PubMed2002

Improvement in zirconia osseointegration by means of a biological glass coating: An in vitro and in vivo investigation.

The biocompatibility and osseointegration of zirconia (ZrO(2)), either coated with RKKP bioglazeor uncoated, were evaluated in vitro and in vivo. The in vitro test was performed in human osteoblasts, whereas maximal sensitization was performed in 23 Dunkin Hurtley guinea pigs. RKKP bioglaze-coated and uncoated (controls) ZrO(2) cylinders were implanted in the distal femoral epiphyses of 14 Sprague-Dawley rats under general anesthesia, and animals were sacrificed at 30 and 60 days. Lactate dehydrogenase, alkaline phosphatase, and Thiazolyl Blue (MTT) were tested in vitro. A graded score was used for evaluating the results of the sensitization test. Histomorphometry and microhardness testing were performed to quantify the osseointegration rate, as well as bone quality around the implants. Neither in vitro cytotoxicity nor sensitization were observed. Histomorphometry demonstrated that at 30 days, the affinity index was significantly higher in coated implants than in uncoated ones (p < 0.05); at 60 days, the behavior of coated implants was better than that of uncoated ones, but differences were not significant. Significant increases in bone microhardness were found at 1000 microm from the interface area for both uncoated (p < 0.0005) and RKKP bioglaze-coated (p < 0.0005) ZrO(2), and also within 200 microm from the interface (p = 0.014) but only for coated ZrO(2.) These results suggest that RKKP bioglaze-coated ZrO(2) permits biocompatible devices with improved osseointegration properties to be manufactured.

Animals↗
PubMed2002

Oestrogens, via transforming growth factor alpha, modulate basic fibroblast growth factor synthesis in hypothalamic astrocytes: in vitro observations.

The data presented here show that, in cultures of type 1 astrocytes obtained from the hypothalamus of neonatal female rat, 17beta-oestradiol is able to increase both the mRNA and the protein levels of basic fibroblast growth factor (bFGF). In particular, after 24 h of exposure to 17beta-oestradiol (10(-9) and 10(-10) m), an increase of messenger levels of bFGF appears in hypothalamic type 1 astrocytes. Similarly, an induction of bFGF protein is also evident at this time of exposure. The effect on the mRNA and protein levels of bFGF is blocked by the presence in the medium of an antibody raised against the transforming growth factor alpha (TGFalpha) receptor. This observation indicates that, TGFalpha, whose synthesis is modulated by oestrogens in hypothalamic astrocytes and which is able to increase, both the mRNA and the protein levels of bFGF in our experimental model, may act as the mediator of the oestrogenic induction of bFGF. Hypothalamic astrocytes, together with hypothalamic neurones synthesizing and secreting luteinizing hormone-releasing hormone (LHRH), form the LHRH network in conjunction with other neuronal systems. Gonadal steroids in general, and oestrogens in particular, play an important role in the control of the activity of this network. In addition, bFGF and TGFalpha, two growth factors released from astrocytes, are able to influence the activity of LHRH neurones. The present observations suggest that oestrogens may also act on LHRH neurones in an indirect fashion (i.e. by modulating the expression of bFGF and TGFalpha in glial cells).

Animals↗
PubMed2002

Osseointegration of sandblasted or anodised hydrothermally-treated titanium implants: mechanical, histomorphometric and bone hardness measurements.

The improvement of the implant-bone interface is still an open problem in the long-term mechanical stability of cementless fixed implants. Mechanical, histomorphometric and bone hardness measurements were performed in sheep femoral cortical bone implants at 8 and 12 weeks from surgery to compare in vivo the osseointegration of titanium screws (psi 3.5 mm x 7 mm length) with two different surface treatments: sandblasting with 70-100 microm HA followed by acid etching with HNO3 (Group A) and Ca-P anodization followed by a hydrothermal treatment (Group B). No significant differences were found for maximum push-out force and interfacial strength between groups at both experimental times. No significant difference was observed for Bone Ingrowth between groups at both experimental times, while the Affinity Index of Group B was significantly higher (7.5%, p<0.05) and lower (10.2%, p<0.05) than that of Group A at 8 and 12 weeks, respectively. Finally, a significant increase in bone microhardness measured within 200 microm from the interface and inside the thread depth of Group A was observed between the two experimental times (p<0.05). In conclusion, present findings show that osseointegration may be accelerated by adequate surface roughness and bioactive ceramic coating such as current tested treatments which enhance bone interlocking and mineralization.

Animals↗
PubMed2001

Aromatase expression and activity in male and female cultured rat hypothalamic neurons: effect of androgens.

Aromatase is possibly involved in male brain sexual differentiation. Aim of these experiments was to evaluate the role of testosterone (T) and of DHT, in the regulation of aromatase expression and activity. The experiments were done utilizing rat primary cultures of hypothalamic neurons from 16-day old embryos sex-screened by SRY gene. Aromatase expression was assessed semiquantitatively by RT-PCR using a neuronal marker (MAP2c) as coamplification product; enzymatic activity was estimated by the 3H(2)O method. The results indicate that (1) cultured neurons possess a functional aromatase, which increases significantly during a 5-days culture period; (2) neurons from males possess a higher expression and activity of the enzyme than females; (3) androgens negatively control expression/activity of aromatase in males, DHT is more active than T; (4) on the contrary, in females T produces a small stimulation of aromatase expression, but not of activity (DHT has produced inconsistent results). The results obtained in this model indicate that T does not stimulate aromatase; therefore, it is not responsible for triggering the perinatal enzymatic peak, nor for the sexual dimorphic aromatase expression. A model is proposed in which DHT might induce, at least in males, the descending phase of the aromatase peak.

Animals↗
PubMed2001

Two active molecular phenotypes of the tachykinin NK1 receptor revealed by G-protein fusions and mutagenesis.

The NK1 neurokinin receptor presents two non-ideal binding phenomena, two-component binding curves for all agonists and significant differences between agonist affinity determined by homologous versus heterologous competition binding. Whole cell binding with fusion proteins constructed between either Galpha(s) or Galpha(q) and the NK1 receptor with a truncated tail, which secured non-promiscuous G-protein interaction, demonstrated monocomponent agonist binding closely corresponding to either of the two affinity states found in the wild-type receptor. High affinity binding of both substance P and neurokinin A was observed in the tail-truncated Galpha(s) fusion construct, whereas the lower affinity component was displayed by the tail-truncated Galpha(q) fusion. The elusive difference between the affinity determined in heterologous versus homologous binding assays for substance P and especially for neurokinin A was eliminated in the G-protein fusions. An NK1 receptor mutant with a single substitution at the extracellular end of TM-III-(F111S), which totally uncoupled the receptor from Galpha(s) signaling, showed binding properties that were monocomponent and otherwise very similar to those observed in the tail-truncated Galpha(q) fusion construct. Thus, the heterogenous pharmacological phenotype displayed by the NK1 receptor is a reflection of the occurrence of two active conformations or molecular phenotypes representing complexes with the Galpha(s) and Galpha(q) species, respectively. We propose that these molecular forms do not interchange readily, conceivably because of the occurrence of microdomains or "signal-transductosomes" within the cell membrane.

Amino Acid Sequence↗
PubMed2001

Enhanced fluorescence resonance energy transfer between spectral variants of green fluorescent protein through zinc-site engineering.

Although spectral variants of GFP should in theory be suited for fluorescence resonance energy transfer (FRET) and therefore suited for studies of protein-protein interactions, the unfavorable location of the fluorophore 15 A deep inside the GFP molecule has especially impaired this application. Here, metal-ion site engineering around the dimerization interface known from the X-ray structure of GFP is applied to the cyan and the yellow spectral variant of GFP to stabilize the heterodimeric form of these molecules and thereby increase FRET signaling. The FRET signal, determined as the ratio between the maximal emission for the yellow variant, 530 nm, and the cyan variant, 475 nm, during excitation of the cyan variant at 433 nm was increased up to 8-10-fold in the presence of 10(-4) M ZnCl2 by engineering of two symmetric metal-ion sites being either bidentate or tridentate. A similar increase in FRET signaling was however obtained in a pair of molecules in which a single bidentate metal-ion site was generated by introducing a zinc-binding residue in each of the two spectral variants of GFP and therefore creating an obligate heterodimeric pair. It is concluded that FRET signaling between spectral variants of GFP can be increased by stabilizing dimer formation and especially by favoring heterodimer formation in this case performed by metal-ion site engineering.

Amino Acid Sequence↗
PubMed2001

Steroid effects on the gene expression of peripheral myelin proteins.

The present article summarizes recent observations obtained in our laboratory which clearly indicate that sex steroids exert relevant effects on the peripheral nervous system. In particular, the following important points have emerged: (1) Steroids exert stimulatory actions on the synthesis of the proteins proper of the peripheral myelin (e.g., glycoprotein Po and peripheral myelin protein 22) in vivo and on the Schwann cells in culture; (2) in many cases the actions of hormonal steroids are not due to their native molecular forms but rather to their metabolites (e.g., dihydroprogesterone and tetrahydroprogesterone in the case of progesterone; dihydrotestosterone and 5 alpha-androstane-3 alpha,17 beta-diol in the case of testosterone); (3) the mechanism of action of the various steroidal molecules may involve both classical (progesterone and androgen receptors) and nonclassical steroid receptors (GABA(A) receptor); and finally, (4) the stimulatory action of steroid hormones on the proteins of the peripheral myelin might have clinical significance in cases in which the rebuilding of myelin is needed (e.g., aging, peripheral injury, demyelinating diseases, and diabetic neuropathy).

Animals↗
PubMed2001

Ernst Knobil.

Explore the source record for details and available documents.

Endocrinology↗
PubMed2001

Formation and effects of neuroactive steroids in the central and peripheral nervous system.

This chapter summarizes several observations that emphasize the importance of neuroactive steroids in the physiology of the central and peripheral nervous systems. A new, and probably important, concept is emerging: Neuroactive steroids not only modify neuronal physiology but also intervene in the control of glial cell functions. The data presented here underscore that (1) the mechanism of action of the various steroidal molecules may involve both classical (progesterone and androgens) and nonclassical steroid receptors [gamma-aminobutyric acid type A (GABAA) receptor], (2) in many instances, the actions of hormonal steroids are not due to their native molecular forms but to their 5 alpha- and 3 alpha,5 alpha-reduced metabolites, (3) several neuroactive steroids exert dramatic actions on the proteins proper of the peripheral myelin (e.g., glycoprotein Po and peripheral myelin protein 22), and (4) the effects of steroids and of their metabolites might have clinical significance in cases in which the rebuilding of the peripheral myelin is needed (e.g., aging, peripheral injury).

Androgens↗
PubMed2001

Interactions between growth factors and steroids in the control of LHRH-secreting neurons.

How the gene expression and the release of luteinizing hormone releasing hormone (LHRH) are controlled in LHRH-secreting neurons is a very crucial and still debated topic of the neuroendocrinology. Several observations present in literature have recently indicated that glial cells may influence the activity of hypothalamic LHRH-secreting neurons, via the release of growth factors. The present review will summarize data obtained in our laboratory indicating that: (a) type 1 astrocytes, a kind of glial cells, are able to release in vitro growth factors belonging to the transforming growth factors beta (TGFbeta) family (i.e. TGFbeta1 and TGFbeta2) which influence the gene expression and the release of the decapeptide in immortalized LHRH-secreting neurons; (b) glial cells are also able to influence the steroid metabolism occurring in these neurons and in some cases this effect is exerted by TGFbeta1; (c) the mRNA levels of TGFbeta1 and of basic fibroblast growth factor (bFGF), another growth factor involved in the control of LHRH-secreting neurons, are modified in the rat hypothalamus during the different phases of the estrous cycle; (d) steroid hormones are able to modulate the gene expression of TGFbeta1 and bFGF both in vivo (i.e. in the whole hypothalamus of ovariectomized rats) and in vitro (cultures of type 1 astrocytes). On the basis of these results a possible functional correlation in the control of LHRH-secreting neurons between growth factors and gonadal steroids will be discussed and proposed.

Animals↗
PubMed2001

Neuroactive steroids and peripheral myelin proteins.

The present review summarizes observations obtained in our laboratories which underline the importance of neuroactive steroids (i.e., progesterone (PROG), dihydroprogesterone (5alpha-DH PROG), tetrahydroprogesterone (3alpha, 5alpha-TH PROG), testosterone (T), dihydrotestosterone (DHT) and 5alpha-androstan-3alpha,17beta-diol (3alpha-diol)) in the control of the gene expression of myelin proteins (i.e. glycoprotein Po (Po) and the peripheral myelin protein 22 (PMP22)) in the peripheral nervous system. Utilizing different in vivo (aged and adult male rats) and in vitro (Schwann cell cultures) experimental models, we have observed that neuroactive steroids are able to stimulate the mRNA levels of Po and PMP22. The effects of these neuroactive steroids, which are able to interact with classical (progesterone receptor, PR, and androgen receptor, AR) and non-classical (GABA(A) receptor) steroid receptors is further supported by our demonstration in sciatic nerve and/or Schwann cells of the presence of these receptors. On the basis of the observations obtained in the Schwann cells cultures, we suggest that the stimulatory effect of neuroactive steroids on Po is acting through PR, while that on PMP22 needs the GABA(A) receptor. The present findings might be of importance for the utilization of specific receptor ligands as new therapeutical approaches for the rebuilding of the peripheral myelin, particularly in those situations in which the synthesis of Po and PMP22 is altered (i.e. demyelinating diseases like Charcot-Marie-Tooth type 1A and type 1B, hereditary neuropathy with liability to pressure palsies and the Déjérine-Sottas syndrome, aging, and after peripheral injury).

Aging↗
PubMed2001

Control of the expression of human neuropeptide Y by leptin: in vitro studies.

Neuropeptide Y (NPY) participates in the regulation of reproduction and food intake. The adipose-secreted hormone, leptin, has also been involved in these processes, and has been shown to exert its effects in part by controlling NPY synthesis and release at the hypothalamic level. In the present study, we utilized the SH-SY5Y human neuroblastoma cell line, to study the leptin-NPY interrelationships. SH-SY5Y cells were found to express leptin receptors (RT-PCR and Western blot analyses). A 24-h treatment with leptin at different concentrations did not affect NPY gene expression, but resulted in a stimulation of NPY release. This stimulated secretion was blocked by the combined treatment with leptin and the muscarinic agonist carbachol or the phorbol ester TPA. Leptin and carbachol also caused an increased intracellular content of NPY. In conclusion, the SH-SY5Y human neuroblastoma cell line appears to be a suitable in vitro model for studying the pharmacological effects of leptin on the biosynthesis and secretion of NPY.

Blotting, Northern↗
PubMed2001

Haemodynamic and volumetric monitoring during haemorrhagic shock in swine.

Various studies have been performed concerning haemodynamics in the shock state. The aim of this study was to examine if a haemodynamic approach based on volumetric indices can offer a new method of evaluation. Volumetric measurements of ventricular filling and cardiac function were compared with classical haemodynamic variables during induced haemorrhagic shock in swine. Twelve hybrid swine were anaesthetized and underwent arteriectomy to induce haemorrhagic shock. Blood was collected in ACD treated bags and reinfused via the same vein after a shock period of 90 min. Haemodynamic and volume measurements were evaluated. Seven swine survived to complete the protocol and reached the final experimental time (90 min after reinfusion), while the remaining five died 1 h after reinfusion. Concerning the haemodynamics, afterload changes characterized the haemorrhagic shock period, while blood volume distribution dictated ventricular filling and ventricular kinetics during the post-reinfusion period. Systemic vascular resistance was different in the two groups. This study suggests that blood volumetric evaluations can offer better comparative data than pulmonary catheterisation for a precise assessment of cardiac output. Preload values have turned out to be of greater relevance than traditional pressure variables.

Animals↗
PubMed2001

5Alpha-reductase type 2 and androgen receptor expression in gonadotropin releasing hormone GT1-1 cells.

Gonadal steroids are potent modulators of gonadotropin releasing hormone (GnRH) secretion, and androgen binding sites and 5alpha-reductase activity have been found in the immortalized GnRH secreting cell line GT1-1, suggesting the existence of a direct androgenic control of GnRH dynamics. Two isoforms of the 5alpha-reductase have been cloned with very different biochemical/functional properties: 5alpha-reductase type 1 (widely distributed in the body) and 5alpha-reductase type 2 (confined in androgen target structures). We have analysed whether, in GT1-1, androgen binding sites are linked to "classical" androgen receptor, and which 5alpha-reductase isoform is active. Reverse transcriptase-polymerase chain reaction analysis showed that the mRNAs coding for androgen receptor and for the two 5alpha-reductase isoforms are all expressed in GT1-1 cells. However, the 5alpha-reductase enzymatic reaction showed a peak of activity at a narrow pH around 5.5, the optimum for the 5alpha-reductase type 2. The affinity for testosterone, of the enzyme present in GT1-1 cells, was very similar to that observed for the recombinant type 2 isozyme expressed in yeasts. The data indicate that GT1-1 cells (i) express a "classical" androgen receptor and (ii) contain the 5alpha-reductase type 2 isoform, a specific marker of androgen-responsiveness.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2001

Hypothalamic transforming growth factor beta1 and basic fibroblast growth factor mRNA expression is modified during the rat oestrous cycle.

The present observations show that the mRNA levels of two growth factors, previously described to be involved in the control of neurones synthesizing the luteinizing hormone releasing hormone (LHRH) [i.e. transforming growth factor beta1 (TGFbeta1) and basic fibroblast growth factor (bFGF)], fluctuate in the hypothalamus of adult female rats during the oestrous cycle. In particular, the expression of TGFbeta1-mRNA shows a peak on the morning of the day of proestrus, which precedes the increased secretion of the two gonadotrophins that occurs on that day. In the case of bFGF, the peak is evident in the evening of the same day and is concomitant with that of the gonadotrophins. We evaluated the effects of ovariectomy and of exogenous oestrogens on the mRNA levels of these two growth factors in the hypothalamus. The data indicate that 3 weeks of ovariectomy are not able to change the hypothalamic messenger levels of the two growth factors considered, which remain at the levels found in diestrus 1, and that 17beta-oestradiol is able to induce a significant increase of both TGFbeta1- and of bFGF-mRNA levels in the hypothalamus of the ovariectomized rat. The present in vivo observations support the concept, previously proposed on the basis of in vitro data, that growth factors, such as TGFbeta1 and bFGF, play a role in the hypothalamic control of reproduction, and suggest that the control of LHRH dynamics involves a strict cooperation between gonadal steroids and growth factors.

Animals↗