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Biomedical subjects

M Governa

Publications and source records attributed to M Governa.

At least 19 recordsLinked to original sources
PubMed2006

Deep burn of the hands: Early surgical treatment avoids the need for late revisions?

An eight years experience in the management of deep hand burns is presented. We reviewed 116 cases of patients surgically treated with escarectomy and skin autograft. Seventy eight of them underwent early surgery within the first 4-6 days from injury, while 38 were conservatively treated in the fist stage and only lately surgery was performed (usually after the 14th day). In all patients, we applied the same post operative topic treatment and rehabilitation protocol. Several months after first admission, only 6(7.7%) of early treated patients needed secondary correction for unaesthetic and functionally debilitating scars versus 14(36.8%) of the late treated group. Our review confirm the importance of performing early surgery of deep burns of the hands, whenever possible, in order to achieve best results and shows it's utility in reducing re-admissions for secondary revisions.

Adolescent↗
PubMed2004

Crystalline silica induces apoptosis in human endothelial cells in vitro.

We investigated whether incubation of cultured human aortic endothelial cells (HAEC) with crystalline silica at the concentration 1 cm2/ml (chosen on the basis of a pilot experiment) leads to alterations typical of apoptosis. The binding of annexin V as early, and DNA fragmentation as late events of apoptosis were measured besides the number of cells with depolarized mitochondria. The generation of reactive oxygen species (ROS) by HAEC in presence of silica was determined as well as silica ability to in vitro generate hydroxyl radicals was investigated. After 18 h of silica incubation, about 30% of viable cells bound annexin V. After 24 h of silica treatment, the percentage of cells with fragmented DNA (Tunel positive) was 27% and it increased up to 50% after 48 h, whereas in untreated cells this percentage was 7% and 11% after 24 and 48 h, respectively. The presence of fragmented DNA in cells treated with silica was confirmed by agarose gel electrophoresis. In agreement with these results showing an induction of HAEC apoptosis by silica incubation, the number of cells with depolarized mitochondria was significantly higher after silica treatment as compared to the control. Apoptosis was also obtained with silica added to aliquots of anti-C5a-absorbed-medium. In the cells exposed to silica there was a significant increasing of ROS generation in comparison to the untreated cells. Apoptosis might be due to peroxidative stress since silica can generate hydroxyl radicals.

Annexin A5↗
PubMed2000

In vitro cleavage by asbestos fibers of the fifth component of human complement through free-radical generation and kallikrein activation.

Chrysotile and crocidolite fibers incubated in normal human plasma (NHP) generated from the C5 component of complement C5a-type fragments that stimulated polymorphonuclear leukocyte (PMN) chemotaxis. Absorption of NHP with antiserum against C5a totally abolished neutrophil chemotactic activity. Asbestos fibers also produced C5a small peptides in the presence of ethylene glycol bis(beta-aminoethyl ether) N,N,N'N'-tetraacetic acid (EGTA) but not ethylene diamine tetraacetic acid (EDTA). Activation of C5 was significantly inhibited when asbestos fibers were pretreated with iron chelators such as sodium dithionite (DTN), deferoxamine (DFX), or ascorbate (AA). Concentration-related inhibition of C5 activation was also observed when asbestos fibers were added concurrently to plasma in the presence of DFX, 1,3-dimethyl-2-thiourea (DMTU), a strong hydroxyl scavenger, or aprotinin (APR), a specific protease inhibitor. Further, chrysotile and crocidolite significantly increased plasma kallikrein activity. Data demonstrate that asbestos-induced C5 activation plays a role in inflammatory reactions characteristic of asbestosis through mechanisms involving iron ions, hydroxyl radicals, and oxidized C5-ike fragments. The ferrous ions present at the asbestos fiber surface trigger this activation and catalyze, via Fenton reaction, the production of hydroxyl radicals, which in turn convert native C5 to an oxidized C5-like form. This product is then cleaved by kallikrein, activated by the same asbestos fibers, yielding an oxidized C5a with the same functional properties as C5a.

Adult↗
PubMed1999

Role of iron in asbestos-body-induced oxidant radical generation.

Asbestos bodies (AB) were harvested from human lung tissue digests and isolated from uncoated asbestos fibers. Samples containing 1000 AB were added to a reactive solution to investigate the ability of AB to oxidize deoxy-D-ribose and generate reactive oxygen species (ROS) in the presence of ascorbate and hydrogen peroxide as determined by formation of thiobarbituric acid (TBA)-reactive products. Three types of asbestos fibers were tested for comparison, since they are known to be able to produce ROS. The absorbance values measured with 1000 AB were significantly higher than those observed with 1000 fibers of the three types of asbestos. Since in our reaction system the only source of transition metals was the iron-rich AB, data suggest iron derived from the ferritin coating of AB was involved in oxidant generation. Addition of iron to AB enhanced TBA-reactive product formation, while chelation of Fe with deferoxamine reduced this reaction. Hydroxyl radical scavengers 1,3-dimethyl-2-thiourea (DMTU) and mannitol (MN) also effectively blocked TBA-reactive product generation. Data indicate the importance of Fe in AB-induced oxidant damage. With the addition of polymorphonuclear leukocytes (PMN) to AB, incubation in the reactive solution gave very high amounts of TBA-reactive products, but using a reactive solution devoid of ascorbate, very low amounts of TBA-reactive products were generated. In the latter condition, the superoxide of cell membranes probably reduced and removed iron from AB-coating ferritin, but less effectively than ascorbate. Further after the possible reoxidation of Fe2+, Fe3+ could be coordinated by lactoferrin. Since such availability of reductant is never approached in living systems, the iron in the AB coating is unlikely to function as a catalyst of Fenton-type reactions in vivo.

Asbestos↗
PubMed1998

Wollastonite fibers in vitro generate reactive oxygen species able to lyse erythrocytes and activate the complement alternate pathway.

Wollastonite fibers were tested in vitro for their ability to produce reactive oxygen species (ROS) with two different systems: a cell-free reactive mixture containing deoxyribose and a polymorphonuclear leukocyte suspension. After adding the fibers, we measured the thiobarbituric acid-reactive substances produced by deoxyribose degradation and luminol-enhanced chemiluminescence, respectively. Compared with asbestos, wollastonite fibers produced higher ROS levels both in the PMN suspensions and in the cell-free reactive mixtures. A large amount of these ROS were not hydroxyl radicals. Indeed we obtained remarkable differences in ROS generation between unground and ground wollastonite fibers and negative results with fibers modified with ferric chloride and dithionite. In addition, ROS generation was partially inhibited (by 46-54%) in the reactions performed in the presence of 1,3-dimethyl-2-thiourea (DMTU), a strong hydroxyl radical scavenger. Wollastonite fibers were also analyzed for their ability to lyse erythrocytes and activate complement. Hemolytic potency was about twice that of chrysotile and half that of crocidolite. The levels of complement activation (via the alternate pathway) were about four-fifths of those measured in zymosan-activated plasma (a typical stimulus used to activate the alternate pathway), equal to those obtained with crocidolite, and two-thirds of those found with chrysotile. The addition of DMTU markedly reduced both these activities. Since asbestos fiber toxicity is mainly due to hydroxyl radical generation, our results indicate that wollastonite fibers are probably less toxic than asbestos fibers.

Adult↗
PubMed1998

Decrease in peripheral blood polymorphonuclear leukocyte chemotactic index in endometriosis: role of prostaglandin E2 release.

OBJECTIVE: To investigate the effect of disease on peripheral blood polymorphonuclear leukocyte chemotactic index and natural killer cell cytotoxicity and to provide additional information concerning the cell-mediated immune function in endometriosis. METHODS: Chemotactic index of peripheral blood polymorphonuclear leukocytes, natural killer cell activity, and plasma estradiol (E2) and plasma prostaglandin (PG) E2 levels were evaluated in 46 women who underwent laparoscopy or laparotomy for pelvic pain, infertility, and/or benign adnexal masses. RESULTS: The 20 women (43%) with endometriosis showed a decrease in peripheral blood polymorphonuclear leukocyte chemotactic index, related to advanced disease stage (P < .001). A significant inverse correlation was observed between plasma PGE2 levels and chemotactic index in stage III and IV endometriosis (r = -.73, P = .004). Similarly, natural cytotoxicity was decreased significantly with respect to the stage of endometriosis (P = .004) and related inversely to plasma PGE2 levels (r = -.74, P = .003). A direct relationship was observed between PGE2 and plasma E2 levels (r = .59, P = .006). CONCLUSION: Advanced endometriosis is associated with decreased peripheral blood polymorphonuclear leukocyte chemotactic index and natural killer cytotoxicity, which may be related to plasma PGE2 and E2 levels.

Adult↗
PubMed1996

Distally based dorsalis pedis island flap for a distal lateral electric burn of the big toe.

Reconstruction of the small defects in the distal portion of the foot has always represented a difficult problem. A case of a young man with a deep electric burn of the distal lateral side of the big toe successfully treated with a distally based dorsalis pedis island flap based on the first dorsal metatarsal artery (FDMA) is presented. The donor site area of the dorsum of the foot was grafted, and deambulation was reassumed 3 weeks later. Advantages; limits and anatomical consideration regarding the viability of the flap are also discussed.

Adult↗
PubMed1996

Fluid replacement in burned patients.

Burn injury involves a large amount of water, electrolytes and proteins loss trough the burn wound. For this reason, to avoid shock, a wide infusion of fluid is necessary in the first hours after trauma. Many reanimation formulas were proposed in the past years, with different composition: saline, colloids, plasma. The authors have studied 40 burned patients admitted in Verona Burn Center within 4 hours after burn, with burns over 30% of the body surface area. Twenty of them were treated with Baxter reanimation formula (ringer lactated saline, RLS) while the others with Monafo hypertonic lactated saline (HLS), modified by Milan Burn Center. The two randomized groups were assessed and compared. In RLS group total fluid volume infused was higher while sodium requirements was lower than in HLS patients, with statistically significative difference (p < 0.01). On the contrary, in HLS group, potassium administered was perhaps twice if compared with the other. Haematocrit, urine output and urine osmolarity were adequate in both the groups, and did not showed statistical differences, such as serum proteins concentration, that was low in all patients, while a significative difference was noted in urine osmolarity (p < 0.01). A metabolic alkalosis was present in HLS patients, while, on the other hand, serum nitrogen was significantly higher (p < 0.05), in the first 48 hours after burn, in RLS group. Patients were assessed for pre-existing diseases too, and data showed that complications were lower in HLS than in RLS group. HLS resuscitation formula guarantees a good electrolytes balance with lower fluid load, reducing tissue oedema and complication rate. Mortality rate was higher in HLS, may be for an higher Roy index in this group.

Acid-Base Equilibrium↗
PubMed1996

Skin expansion in burn sequelae: results and complications.

Before Radovan introduced skin expansion, burn sequelae were treated with skin grafts, local or distant flap, with an high morbidity on the donor site. Actually this technique is well known and standardized procedure that allows to obtain local flaps with the same characteristics in colour, texture, hair and sensitivity of the normal skin. The authors analyze their experience in the treatment of burn sequelae from 1985 to 1995. During this period, 157 patients underwent surgery to correct burn scars and contracture, utilizing 262 skin expanders. The implants were positioned on the fascial layer; antibiotic and drainage were routinely used. The inflation of the expander began 2 weeks after surgery, and hyperexpansion was the rule, when possible. Only in 6.4% (10 patients) expansion failed, while in the remaining cases good partial (in patients with too large scars) or total results were achieved. Complication rate in skin expansion is high. In this series complication occurred in 73 of 262 expansion, but 43 were easily solved. So only in 30 expansions the final outcome was influenced by complication, with higher incidence in neck and in lower extremities. Results were generally satisfactory, with an improvement of scars and minimal donor site morbidity. With a careful selection of the patients, skin expansion offers a good solution for burn sequelae, complications can be reduced and successfull results achieved.

Adult↗
PubMed1995

In vitro biological effects of clay minerals advised as substitutes for asbestos.

We studied one sample of commercial sepiolite and two samples of commercial vermiculite--clay minerals proposed as replacements for asbestos--and tested in vitro their abilities to activate complement, to lyse erythrocytes, and to elicit the production of reactive oxygen species (ROS) with human polymorphonuclear leukocytes (PMN) or bovine alveolar macrophages (AM); their behavior was compared with that of asbestos fibers obtained from the Union International Contra Cancer (UICC) as reference standards, as well as with kaolinite and illite, main members of the clay mineral family. Since in short-term in vitro tests the biological activity of mineral particles seems especially related to the active sites on their surface, we first measured the specific surface area of each mineral. Sepiolite was unreactive in two of the three tests we used (complement activation and ROS production) and able to lyse a minimal percentage of red blood cells. Vermiculite was shown to be incapable of activating complement, to have a moderate hemolytic activity and a high ability to elicite ROS production, although lower than that of chrysotile. Sepiolite, therefore, might be of more interest than vermiculite, given the low level of biological effects detected during the tests used to compare both clay minerals with asbestos fibres. The ROS production does not seem to require phagocytosis. A high ROS production was observed with kaolinite: this result casts doubt on the ability of pathogenic mineral dusts in vitro to induce a greater release of ROS than nonpathogenic mineral dusts.

Acridines↗
PubMed1994

Chemotactic activity of human polymorphonuclear leukocytes and industrial xenobiotics: a brief review.

This review deals with some of our contributions to the use of chemotaxis, as a tool in evaluating effects of industrial xenobiotics on PMN, either in vitro or ex vivo. In vitro experiments have shown that lead, arsenic, styrene and 2,5-hexanedione, a major neurotoxicant metabolite of n-hexane, reduce chemotaxis. The most important results of ex vivo experiments have confirmed those obtained in vitro with styrene and 2,5-hexanedione: a significant reduction of chemotaxis was indeed observed in PMN harvested from workers exposed to low levels of n-hexane or styrene who did not show any sign of biochemical or clinical alteration. After 3 weeks under non-exposed conditions, the chemotactic indexes were markedly increased in most of the workers which were exposed to styrene and in all the workers exposed to n-hexane, all of whom have shown a reduced chemotaxis at the first blood sampling. Moreover chemotaxis was found to be significantly reduced at relative low levels of lead: results of the in vitro and ex vivo experiments show a comparable ranking of midpoint inhibition concentrations. We are only at the dawn of the understanding of the relation between occupational xenobiotics and PMN chemotaxis. This research area is still promising for the future, since PMN chemotaxis seems to be adequate and it must therefore enter in well-defined study protocols for investigating the potential immunotoxicity of occupational chemicals to which humans are exposed at low levels.

Chemotaxis, Leukocyte↗
PubMed1994

Latex-induced asthma in four healthcare workers in a regional hospital.

Hypersensitivity to latex gloves has often been reported in patients who have undergone surgical treatment. Recent reports suggest that latex antigens can produce cutaneous and respiratory symptoms in workers occupationally exposed to latex. Four such cases of healthcare workers who were sensitized through exposure to latex have been observed. Two of these workers presented dermatitis as well as work-related respiratory symptoms, while the others only showed symptoms suggesting occupational asthma. The subjects were diagnosed as having latex hypersensitivity after skin prick-testing, and the immunoglobulin E serum level against latex gave positive results. In addition, changes in methacholine responsiveness also took place. In one case, an occupational exposure test was carried out which resulted in a 24% drop in the FEV1 value after 25 min of inhalation exposure. At least one year after the diagnosis, two nurses (subjects A and D) who had been removed completely from latex exposure experienced no further latex-induced symptoms. The other workers, who have continued working in the same laboratories using vinyl gloves, now display less severe symptoms but require regular anti-allergy treatment.

Adult↗
PubMed1994

Human polymorphonuclear leukocyte chemotaxis as a tool in detecting biological early effects in workers occupationally exposed to low levels of n-hexane.

Human polymorphonuclear leukocytes (PMN) were chosen to measure two cellular end points--chemotaxis and respiratory burst--and to verify whether they could function as biomarkers of early effect in detecting occupational exposure to n-hexane of apparently healthy shoe workers, without any electroneuromyographic (ENMG) abnormality. Chemotaxis, but not respiratory burst, was found to be impaired. A negative linear correlation between chemotaxis of PMN of those workers that had been exposed to n-hexane versus 2,5-hexanedione (2,5-HD) urinary concentrations were found. This negative trend is consistent with our previous in vitro experimental findings: it was observed that the progressive addition of 2,5-HD to PMN suspensions inhibited chemotaxis in a dose-dependent mode, while chemiluminescence was not modified. Now we have confirmed in vivo that chemotaxis is more sensitive than the respiratory burst response to 2,5-HD. Such results justify the interest in the behaviour of PMN harvested from workers exposed to n-hexane. Since significant inhibition of chemotactic activity was observed in some workers whose urinary 2,5-HD levels were lower than 5 mg l-1, which is the biological exposure index suggested by ACGIH, this study suggests that PMN chemotaxis may be proposed as a useful biomarker in detecting occupational exposure to low level of n-hexane.

Adolescent↗
PubMed1991

Effects of lead on polymorphonuclear leukocyte (PMN) functions in occupationally exposed workers.

Previous in vitro experiments have shown that lead can inhibit PMN chemotaxis, phagocytosis and superoxide formation. Moreover, we have observed an inhibition of PMN chemotaxis in workers occupationally exposed to lead with a mean blood lead concentration of 3.06 mumol/l. The present study was carried out to evaluate locomotion and luminol assisted chemiluminescence (CL) of polymorphonuclear leukocytes (PMN) harvested from ten lead occupationally exposed workers with blood lead concentrations of 1.59 mumol/l (SD 0.27 mumol/l). Since lipids affect PMN activity and lipid composition is modified in erythrocytes of lead workers, PMN lipids were also studied. Ten healthy male subjects of the same age were taken as controls. Chemotaxis, i.e. locomotion stimulated through a specific membrane receptor, was impaired in the PMN of lead workers, but random migration, i.e. unstimulated cell locomotion, and respiratory burst were both unmodified. Cholesterol and phospholipids were not changed, but the percentage of arachidonic acid was significantly increased. The release of LTB4, generated by the oxidative metabolism of arachidonic acid, was increased. CL, which detects reactive oxygen species (ROS), was unmodified, but this lack of change could be the result of an increase in ROS, due to the augmentated percentage of arachidonic acid, and of a decrease in ROS, due to a direct inhibitory effect of lead on ROS generation. On the basis of the results from these ex vivo experiments, the conclusion that chemotaxis is the PMN function primarily affected by lead was confirmed. PMN are considered to be one of the first cellular targets for the action of lead; low exposure to lead modifies their activity and mainly modifies chemotaxis and LTB4 production.

Adult↗
PubMed1990

Mortality rate and prognostic indices in 2615 burned patients.

Two thousand six hundred and fifteen burned patients are analysed according to mortality rate and the results are compared with other prognostic indices. Our statistical data are similar to those reported by Feller et al. (1976), but differ from those expected by Roi et al. (1983) and Bull (1971). It is suggested that other burns centres should produce their statistical figures in the same way, thereby producing a wider statistical experience and a more accurate prognostic index. The improvement in the survival rate in our centre in the past 5 years is also discussed.

Age Factors↗