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Biomedical subjects

A Russo

Publications and source records attributed to A Russo.

At least 181 records · Page 10Linked to original sources
PubMed2000

Development and clinical assessment of an artificial cornea.

Keratoprosthesis research has been a gradual, rather fragmentary process with advances being made by isolated groups of researchers. This has arisen partly because of poor funding in the area; research groups which have achieved commercial support have often had constraints upon the full disclosure of their findings. Despite these difficulties there has been real progress over the last decade by several independent groups. This article concentrates upon our own development of a hydrogel core-and-skirt keratoprosthesis, the Chirila KPro, in order to illustrate the scientific and clinical problems common to keratoprosthesis research. Pilot data from a clinical trial is presented and the priorities for future research are discussed.

Animals↗
PubMed2000

Intravenous inotropic agents in the intensive therapy unit: do they really make a difference?

Part of the management of refractory heart failure is treatment aimed at preventing organ damage due to inadequate oxygen delivery, improving hemodynamics, and maximizing cardiac output while maintaining only mildly elevated ventricular filling pressures The aim of this paper is to review the most updated indications on intravenous inotropic agents, and to compare their cardiac and peripheral effects. Finally, clinical implications of their use (alone or in combination) are reviewed.

Adrenergic beta-Agonists↗
PubMed2000

Prolonging proton pump inhibitor-based anti-Helicobacter pylori treatment from one to two weeks in duodenal ulcer: is it worthwhile?

AIMS: To compare the efficacy of one-week versus two-week treatment with lansoprazole, amoxycillin and clarithromycin in inducing healing of Helicobacter pylori-positive duodenal ulcers as well as to investigate the role of several factors, determinant in the ulcer healing process. PATIENTS AND METHODS: Seventy-one active duodenal ulcer patients were randomised to receive one- or two-week treatment with lansoprazole (30 mg bid), clarithromycin (500 mg bid) and amoxycillin (1 g bid), not followed by any additional acid suppressive therapy. Ulcer healing and Helicobacter pylori infection were assessed by endoscopy and urea breath test 4 weeks after the end of treatment. Before entering the trial and four weeks after the end of treatment, dyspeptic symptoms were recorded and scored by a validated questionnaire. The potential effects of a number of clinical variables on the ulcer healing process were evaluated by means of univariate and multivariate analyses. RESULTS: Duodenal ulcer was healed in 80.5% patients treated for one week and in 91.4% patients treated for 2 weeks according to intention-to-treat analysis (p=NS). Ulcer healing was more frequent in the Helicobacter pylori cured patients compared to those with persisting infection (90.9% vs 68.5%; p=0.04). Multivariate analysis did not reveal any significant predictor of duodenal ulcer healing. CONCLUSIONS: Two-week treatment with lansoprazole, amoxycillin and clarithromycin, without continuation of antisecretive therapy, is better, although the difference is not statistically significant, than one-week treatment in healing Helicobacter pylori-positive duodenal ulcer disease. The eradication of Helicobacter pylori is the most important factor related to ulcer healing.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2000

Antioxidant activity and protective effect on DNA cleavage of extracts from Cistus incanus L. and Cistus monspeliensis L.

The genus Cistus includes many typical species of Mediterranean flora; Cistus species are used as antidiarrhetics, as general remedies for treatment of various skin diseases in folk medicine and as anti-inflammatory agents. These species contain flavonoids that are considered to be chain-breaking antioxidants. In this work, we have investigated the effects of crude aqueous extracts from Cistus incanus and Cistus monspeliensis on DNA cleavage and their free-radical scavenging capacity. In addition, their effect on lipid peroxidation in rat liver microsomes was evaluated. These extracts showed a protective effect on DNA cleavage and a dose-dependent free-radical scavenging capacity; Cistus monspeliensis was more active than Cistus incanus; these results were confirmed by a significant inhibition of lipid peroxidation in rat liver microsomes. The experimental evidence, therefore, suggests that because of their antioxidant activity these extracts may offer excellent photoprotection for skin and may be useful in the treatment of human diseases where oxidative stress plays a key role.

Animals↗
PubMed2000

L -propionyl-carnitine as superoxide scavenger, antioxidant, and DNA cleavage protector.

L-Propionylcarnitine, a propionyl ester of L-carnitine, increases the intracellular pool of L-carnitine. It exhibits a high affinity for the enzyme carnitine acetyltransferase (CAT) and, thus, is readily converted into propionyl-coenzyme A and free carnitine. It has been reported that L-propionylcarnitine possesses a protective action against heart ischemia-reperfusion injury; however, the antioxidant mechanism is not yet clear. L-Propionylcarnitine might reduce the hydroxyl radical production in the Fenton system, by chelating the iron required for the generation of hydroxyl radicals. To obtain a better insight into the antiradical mechanism of L-propionylcarnitine, the present research analyzed the superoxide scavenging capacity of L-propionylcarnitine and its effect on linoleic acid peroxidation. In addition, the effect of L-propionylcarnitine against DNA cleavage was estimated using pBR322 plasmid. We found that L-propionylcarnitine showed a dose-dependent free-radical scavenging activity. In fact, it was able to scavenge superoxide anion, to inhibit the lipoperoxidation of linoleic acid, and to protect pBR322 DNA from cleavage induced by H2O2 UV-photolysis.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Bioflavonoids as antiradicals, antioxidants and DNA cleavage protectors.

Flavonoids have recently aroused considerable interest because of their broad pharmacological activity. In fact, flavonoids have been reported to have antiviral, antiallergic, antiplatelet, anti-inflammatory and antitumoral activities. The pharmacological properties of bioflavonoids have been ascribed both to the concomitant inhibition of enzymes involved in the production of free radicals and to their free-radical scavenging and iron chelating capacity. However the antioxidant capacity of bioflavonoids due to free-radical scavenging and/or to iron chelating is still controversial. In this study, we have investigated the free-radical scavenging capacity of bioflavonoids (rutin, catechin, and naringin). In addition, the effects of these polyphenols on xanthine oxidase activity, spontaneous lipid peroxidation, and DNA cleavage were investigated. The bioflavonoids under examination showed a dose-dependent free-radical scavenging effect, a significant inhibition of xanthine oxidase activity, and an antilipoperoxidative capacity. In addition, they showed a protective effect on DNA cleavage.

Animals↗
PubMed2000

Osteocalcin metabolism in the pulmonary circulation.

The aim of this study was to evaluate the role of the pulmonary vessel endothelium in the removal of circulating osteocalcin, by measuring the osteocalcin levels in serum from pulmonary and radial artery blood from 39 patients undergoing aorto-coronary bypass. Because of the discrepancies between methods of measurement, two methods were used. Significant differences were observed in group A (n = 18), tested with heterologous radioimmunoassay (2.85 +/- 0.67 microg l-1 in the pulmonary versus 2.69 +/- 0.67 microg l-1 in the radial artery serum, P<0.001) and in group B (n = 21), tested with a two-site immunoradiometric assay (5.22 +/- 1.46 versus 4.93 +/- 1.36 microg l-1, P<0.01). The percentage differences were -5.54 +/- 4.76% (P<0.001) in group A and -4.99 +/- 8.13% (P<0.01) in group B; the comparison between the percentage differences was not significant. These different osteocalcin concentrations between the two vascular compartments were considered a marker of osteocalcin degradation. Therefore, the study seems to demonstrate that, as well as kidney, liver and bone, the lung is a relevant site of osteocalcin catabolism. The proteolytic activity of pulmonary vessel endothelium seems to involve about 5% of the circulating peptide.

Aged↗
PubMed2000

In vitro tannin acantholysis.

BACKGROUND: Exogenous factors, such as certain drugs, may be involved in the induction of pemphigus. Other offenders sharing a similar chemical composition to these drugs may also play a role. Tannins with their considerable biologic activity were suggested as possible factors. To substantiate the role of tannins in the pathomechanism of pemphigus, the present study examined the acantholytic potential of tannins in vitro. METHODS: Normal human breast skin from patients without any bullous disease was cultured for 3 days in the presence of tannic acid at concentrations of 0.02, 0.05, 0.1, 0.25, 0.5, 1.0, and 2.0 mM. The effect of the tannic acid was microscopically examined in a blind fashion by three independent investigators. RESULTS: In addition to the cytotoxic effect, tannic acid caused marked acantholytic changes, with a clear suprabasal cleavage and intraepidermal acantholytic cells. The acantholytic changes were the most constant and specific effects. They were constantly observed at 1.0 and 2.0 mM, whereas lower concentrations showed changes only in some of the explants. The concentrations needed to exert this effect were notably low. There was a remarkable variability among the subjects who had provided the explants. CONCLUSIONS: The results suggest a possible role of tannin in the disease process of pemphigus. The tannin acantholytic potential was much greater than the potential of known acantholytic drugs, such as penicillamine and captopril. The interindividual variability in susceptibility to acantholysis may explain the variability in the individual potential for developing pemphigus.

Acantholysis↗
PubMed2000

Fast-growing vestibular schwannoma.

A case of a Jehovah's witness affected by an intracanalicular vestibular schwannoma with an extremely fast growth rate is presented. Nine months after presentation, the tumor reached 23 mm in the cerebellopontine angle. A partial removal through a retrosigmoid approach was planned. Because of the presence of a dominant high jugular bulb masquering the internal auditory canal, the intracanalicular portion of the tumor was left in place. The residual tumor grew 12 mm in 2 months. Even after a gross total removal through a middle cranial fossa approach, the tumor recurred, reaching the size of 30 mm in 17 months. A modified transcochlear approach was then performed, and the patient was free of disease at the last radiologic follow-up, 8 months after the surgery. We illustrate our strategy in treating this aggressive benign lesion with unusual behavior.

Case Reports↗
PubMed2000

The saturation loss for plane parallel ionization chambers at high dose per pulse values.

The use of plane parallel ionization chambers with electron beams with high dose per pulse entails dose uncertainties due to the overestimation of the ion recombination factor, k, up to 20% if conventional dosimetric protocols are used. In this work MD-55-2 radiochromic films have been used as reference dosimeters to obtain dose to water per pulse DGAF(w) values for three Novac7 (Hitesys) electron beams of E0 = 5.8 MeV. However, the beam calibration by MD-55-2 films is time consuming and the use of plane parallel chambers is fundamental for a periodic quality control procedure. Three plane parallel chambers have been used and the general formula for the k determination has been tested using the calibration doses, DGAF(w). In particular, consistent ion recombination factors ksat(V0) (with the ion chamber polarized at V0), that follow the Boag theory, have been estimated at different dose per pulse values for the three plane parallel ionization chambers. This means that at present any ion chamber needs a specific ksat (V0) determination by using a reference dosimeter for which the response is independent of the dose rate. An accurate determination of ksat(V0), using a reference quality beam, can be used to determine the dose to water per pulse for electron beams of different quality and geometrical configuration.

Dose-Response Relationship, Radiation↗
PubMed2000

Detection and characterization of micronuclei in a murine liver epithelial cell line, by application of the in vitro cytokinesis block MN assay and PRINS.

The cytokinesis block micronucleus assay was applied to murine cell line C6, derived from fetal liver, after an optimal protocol had been designed. Micronucleus frequencies were assayed after exposure to three concentrations of colcemid or diepoxybutane. Two-colour primed in situ DNA synthesis (PRINS) was applied to simultaneously label telomeric and centromeric (minor satellite DNA) sequences. Both chemicals induced a highly significant increase in MN and the effect was dose dependent. Diepoxybutane did not appear to significantly increase the frequency of centromere-positive micronuclei. Colcemid, as expected, induced high frequencies of centromere-positive micronuclei at all concentrations tested; in addition a significant increase in centromere-negative micronuclei was observed at 10(-5) M. Many centromere-positive micronuclei carried three or four telomeres, thus indicating that a duplicated (non-disjoined) chromosome with two chromatids was contained in the micronucleus. This observation leads to the conclusion that micronuclei deriving from missegregation could be due to errors occurring before the onset of anaphase. The results obtained on C6 cells are in good agreement with those obtained on other cell systems, indicating that this cell line can be considered for in vitro aneuploidy evaluation.

Anaphase↗
PubMed2000

The pro-oxidative activity of SOD and nitroxide SOD mimics.

Native Cu,Zn-SOD and synthetic SOD mimics sometimes demonstrate an apparently anomalous bell-shaped dose-response relationship when protecting various biological systems from oxidative stress. Several mechanisms have been proposed to account for such an effect, including: overproduction of H(2)O(2), peroxidative activity of SOD, and opposing roles played by O(2)(*-) in both initiation and termination of radical chain reactions. In the present study, ferrocyanide and thiols, which are susceptible to one-electron and two-electron oxidation, respectively, were subjected to a flux of superoxide in the presence and absence of SOD or SOD mimics. The results show that 1) either O(2)(*-)/HO(2)(*) or H(2)O(2) alone partially inactivates papain, whereas when combined they act synergistically; 2) nitroxide SOD mimics, but not SOD, exhibit a bell-shaped dose-response relationship in protecting papain from inactivation; 3) SOD, which at low dose inhibits superoxide-induced oxidation of ferrocyanide, loses its antioxidative effect as its concentration increases. These findings offer an additional explanation for the pro-oxidative activity of SOD and SOD mimics without invoking any dual activity of O(2)(*-) or a combined effect of SOD and H(2)O(2). The most significant outcome of an increase in SOD level is a decrease of [O(2)(*-)](steady state), rather than any notable elevation of [H(2)O(2)](steady state). As a result, the reaction kinetics of the high oxidation state of each catalyst is altered. In the presence of ultra-low [O(2)(*-)](steady state), the oxidized form of SOD [Cu(II),Zn-SOD] or SOD mimic (oxo-ammonium cation) does not react with O(2)(*-) but rather oxidizes the target molecule that it was supposed to have protected. Consequently, these catalysts exert an anti- or pro-oxidative effect depending on their concentration.

Antioxidants↗
PubMed2000

Genotype and phenotype factors as determinants for rectal stump cancer in patients with familial adenomatous polyposis. Hereditary Colorectal Tumors Registry.

OBJECTIVE: To identify factors influencing the occurrence of cancer in the rectal remnant in patients with familial adenomatous polyposis (FAP) after colectomy and ileorectal anastomosis (IRA). SUMMARY BACKGROUND DATA: The risk for rectal cancer in patients with FAP after colectomy and IRA remains a major concern. METHODS: Between 1955 and 1997, 371 patients (206 men, 165 women) from the Registry of Hereditary Colorectal Tumors underwent colectomy and IRA as a primary surgical procedure. Survival was estimated using the Kaplan-Meier method. Cox proportional hazard models were fitted to assess the relative excess risk of rectal cancer and to control for confounding factors. A multivariate analysis was performed to assess the relation between cancer risk in the rectum and sex, age, number of rectal polyps, colon cancer, and APC germline mutation. RESULTS: Median follow-up was 81 months. Eighty-nine patients (24%) had colon cancer at the time of surgery. The APC mutation was found in 200 patients. In 27 patients, cancer developed in the retained rectum 1 to 26 years after surgery. The incidence of rectal carcinoma appears to increase with time: at 10, 15, and 20 years after surgery, the cumulative risk was 7.7%, 13.1%, and 23.0%, respectively. Multivariate analysis identified as independent predictors the presence of colon cancer at IRA and a mutation occurring between codons 1250 and 1464; both factors increased the risk nine times. CONCLUSIONS: The presence of cancer at IRA and APC mutation type are the most important risk factors for the future development of cancer in the rectal remnant in patients with FAP.

Adenomatous Polyposis Coli↗
PubMed2000

Radiation, radicals, and images.

Nitroxide stable free radicals exhibit varied chemical and biological properties. Their biological applications have been greatly expanded over the past few years. Not only have they been shown to exhibit potent antioxidant and radioprotective properties, but also they can serve as in vivo functional imaging probes that non-invasively report on the oxygen status and redox properties of tissue, which may have utility in clinical biomedical research.

Animals↗
PubMed2000

PTW-diamond detector: dose rate and particle type dependence.

In this paper the suitability of a PTW natural diamond detector (DD) for relative and reference dosimetry of photon and electron beams, with dose per pulse between 0.068 mGy and 0.472 mGy, was studied and the results were compared with those obtained by a stereotactic silicon detector (SFD). The results show that, in the range of the examined dose per pulse the DD sensitivity changes up to 1.8% while the SFD sensitivity changes up to 4.5%. The fitting parameter, delta, used to correct the dose per pulse dependence of solid state detectors, was delta = 0.993 +/- 0.002 and delta = 1.025 +/- 0.002 for the diamond detector and for the silicon diode, respectively. The delta values were found to be independent of particle type of two conventional beams (a 10 MV x-ray beam and a 21 MeV electron beam). So if delta is determined for a radiotherapy beam, it can be used to correct relative dosimetry for other conventional radiotherapy beams. Moreover the diamond detector shows a calibration factor which is independent of beam quality and particle type, so an empirical dosimetric formalism is proposed here to obtain the reference dosimetry. This formalism is based on a dose-to-water calibration factor and on an empirical coefficient, that takes into account the reading dependence on the dose per pulse.

Diamond↗
PubMed2000

Haematopoietic progenitors from umbilical cord blood.

BACKGROUND/AIM: The aim of this study is to improve the obstetrician-based cord blood collection system and an efficient recovery of CD34+ haematopoietic progenitor stem cells. METHODS: CD34+ cells were purified from total blood using a positive selection enrichment method, called Mini-Macs. RESULTS: The final yield of CD34+ cells we obtained was 10(4) cells/ml, with a CD34+ purity of 99%. CONCLUSION: Our results confirm that, by using this method, it is possible to get a significant stem cell number, thus improving transplanting both peripheral stem cells and umbilical cord ones.

Antigens, CD34↗