[The activation of the phosphotyrosine phosphatase eta is responsible for the somatostatin inhibition of PCCl3 thyroid cell proliferation]

BACKGROUND

This study was aimed to identify possible intracellular effectors of the somatostatin (SST) antiproliferative activity, in PCCl3 thyroid cells.

METHODS

To prove the involvement of r-PTPeta in SST's effect, we studied th proliferative activity of subclones of PCCl3 cells that do or do not express this PTP.

RESULTS

SST inhibited PCCl3 TSH+insulin-dependent cell proliferation through the induction of a phosphotyrosine phosphatase (PTP) activity, detected using the synthetic substrate pNPP (+150%, p<0.01). Conversely, PCCl3 cells stably expressing the v-mos oncogene (PCmos) were completely insensitive to SST antiproliferative effects due to the incapability of SST to increase PTP activity, that correlated with the abolishment of the expression of the receptor-like PTP, r-PTPeta. In the cells in which r-PTPeta was transfected (PCmos/ PTPeta) SST inhibited cell proliferation showing a dose-dependence similar to that observed in PCCl3 cells. Conversely, the transfection of a catalytically inactive mutant of r-PTPeta did not restore the responsivity to SST. Also in PCmos/PTPeta cells SST, treatment increased membrane PTP activity.

CONCLUSIONS

SST inhibition of PCC13 cell proliferation requires the activation of r-PTPeta.

Pregnancy and condyloma. Evaluation about therapeutic effectiveness of laser CO2 on 115 pregnant women

BACKGROUND

At present one of the most common pathologies of the female genital apparatus is infection from HPV. It may be present in the latent form or symptomatic with flat or condylomatous lesions. The condylomatous lesions are particularly interesting in pregnant women on account of the symptoms, complications and methods for treating such lesions. The aim of this study was to evaluate the therapeutic efficacy of laser-vaporization in genital condylomata during pregnancy.

METHODS

From March 1998 through October 2000 we used laser therapy to treat 115 pregnant women with florid genital condylomata. Treatment was given without regard to the gestation period. All the women were treated at least once. Persistent cases (failure of therapy) and recurrence (new infection) were classed according to the gestation week and site of lesion.

RESULTS

Unsuccessful therapy, evaluated on the basis of repeated treatment, was 7.83%. There was no evidence of recurrence in those who received therapy in the third trimester. There were no abortions, particular complications or intrauterine deaths.

CONCLUSIONS

We believe, that at present, the most effective treatment for condylomatoses in pregnant women is laser-vaporization.

[Somatostatinergic control of Kaposi's sarcoma growth through the inhibition of angiogenesis]

Somatostatin and its analogs are active in the inhibition of the proliteration of sst receptor positive endocrine neoplasms, however their activity and mechanism in non-endocrine tumors is not clear. Somatostatin effectively inhibited the growth of a Kaposi's sarcoma xenograft in nude mice, yet in vitro the tumor cells did not express any known somatostatin receptors and were not growth inhibited by somatostatin. Histological examination revealed limited vascularization in the somatostatin treated tumors as compared to the controls. Somatostatin was a potent inhibitor of angiogenesis in an in vivo assay. In vitro, somatostatin inhibited endothelial cell growth and invasion. Migration of monocytes, important mediators of the angiogenic cascade, was also inhibited by somatostatin. Both cells types expressed somatostatin receptor mRNAs. These data demonstrate that somatostatin is a potent anti-tumor angiogenesis compound directly affecting both endothelial and monocytic cells. The debated function of somatostatin in tumor treatment and the design of therapeutic protocols should be reexamined considering these data.

The role of diagnostic hysteroscopy in infertile women

BACKGROUND

Anomalies of the uterus are considered one of the reasons for infertility in women. For this reason we believe diagnostic hysteroscopy is fundamental in screening for infertility. The aim of this study was to verify the incidence of uterine anomalies in sterile couples and evaluate the efficacy of diagnostic hysteroscopy in subjects with possible alterations in this organ.

METHODS

From July through December 2000, 296 hysteroscopies were carried out at the Centro di Sterilità e di Fecondazione Assistita of Perugia University. Of these 223 entered the study because of infertility in couples. The exam was always done between the 7th and 11th day of the cycle using a Hamou 5 mm hysteroscope, without anaesthesia. The uterus was dilated by introducing physiological solution at 50 mmHg pressure. The criteria adopted for hysteroscopic findings were based on: a) cervical canal; b) uterine cavity; c) endometrium, and visualization of the ostium tubae.

RESULTS

Of the 223 women who underwent hysteroscopy screening for infertility 17 (7.62%) had uterine anomalies. Of these 1 was in the cervical canal, 4 had anomalies in both the uterus and cervix, and the remaining 12 had only uterine cavity anomalies. The presence of neoformations was the most commonly found alteration.

CONCLUSIONS

From the results of this study we conclude that diagnostic is a very important method for investigating the reasons for infertility in a couple. From our casuistry the incidence of uterine anomaly is 7.62%. We therefore suggest hysteroscopy be included among the 1st and 2nd level exams for female infertility.

The activation of the phosphotyrosine phosphatase eta (r-PTP eta) is responsible for the somatostatin inhibition of PC Cl3 thyroid cell proliferation

The aim of this study was the characterization of the intracellular effectors of the antiproliferative activity of somatostatin in PC Cl3 thyroid cells. Somatostatin inhibited PC Cl3 cell proliferation through the activation of a membrane phosphotyrosine phosphatase. Conversely, PC Cl3 cells stably expressing the v-mos oncogene (PC mos) were completely insensitive to the somatostatin antiproliferative effects since somatostatin was unable to stimulate a phosphotyrosine phosphatase activity. In PC mos cells basal phosphotyrosine phosphatase activity was also reduced, suggesting that the expression of a specific phosphotyrosine phosphatase was impaired in these transformed cells. We suggested that this phosphotyrosine phosphatase could be r-PTP eta whose expression was abolished in the PC mos cells. To directly prove the involvement of r-PTP eta in somatostatin's effect, we stably transfected this phosphatase in PC mos cells. This new cell line (PC mos/PTP eta) recovered somatostatin's ability to inhibit cell proliferation, showing dose-dependence and time course similar to those observed in PC Cl3 cells. Conversely, the transfection of a catalytically inactive mutant of r-PTP eta did not restore the antiproliferative effects of somatostatin. PC mos/PTP eta cells showed a high basal phosphotyrosine phosphatase activity which, similarly to PC Cl3 cells, was further increased after somatostatin treatment. The specificity of the role of r-PTP eta in somatostatin receptor signal transduction was demonstrated by measuring its specific activity after somatostatin treatment in an immunocomplex assay. Somatostatin highly increased r-PTP eta activity in PCCl3 and PC mos/PTP eta (+300%, P < 0.01) but not in PCmos cells. Conversely, no differences in somatostatin-stimulated SHP-2 activity, (approximately +50%, P < 0.05), were observed among all the cell lines. The activation of r-PTP eta by somatostatin caused, acting downstream of MAPK kinase, an inhibition of insulin-induced ERK1/2 activation with the subsequent blockade of the phosphorylation, ubiquitination, and proteasome degradation of the cyclin-dependent kinase inhibitor p27(kip1). Ultimately, high levels of p27(kip1) lead to cell proliferation arrest. In conclusion, somatostatin inhibition of PC Cl3 cell proliferation requires the activation of r-PTP eta which, through the inhibition of MAPK activity, causes the stabilization of the cell cycle inhibitor p27(kip1).

[Do histologic changes of the upper renal pole in double ectopic ureterocele justify a conservative approach?]

The aim of this study was to review the histology of the upper pole segment in patients with duplex ectopic ureterocele to verify if a less aggressive surgery is justified in the prenatally diagnosed patients. We reviewed the histology of the upper pole segment of 15 consecutive patients with duplex system ectopic ureterocele treated between 1991 and 1999 at the Paediatric Surgery Unit of University Hospital of Messina. The diagnosis of duplex system ectopic ureterocele was made according to the criteria of the Section on Urology of the American Academy of Paediatrics. The histology specimens were assessed for dysplastic, inflammatory and obstructive changes. All 15 patients with duplex system ectopic ureterocele were surgically treated with heminephro-ureterectomy and the surgical specimens were histologically examined. Nine of the 15 patients were prenatally diagnosed. The histology of the upper pole segment of the 9 prenatally diagnosed showed in all patients segmental renal microcystic dysplasia, chondroid metaplasic islands and an inflammatory tubulo-interstitial nephropathy in 6 patients (66.6%) and in 2 (22.2%) nephroblastomatosis. The histology of six the postnatal postnatally diagnosed patients showed in all patients segmental multicystic renal dysplasia, inflammatory tubulo-interstitial nephropathy and segmental parenchymal scars. The upper pole histology of the patients with duplex ectopic ureterocele diagnosed prenatally did not show any evidence of reversible histological change. Considering the histology and the good outcome of patients treated with upper pole nephroureterectomy a less aggressive surgery with preservation of the upper pole does not seem justified.

Effect of the exposure to gentamicin and diltiazem on the permeability of model membranes

Preliminary observations showed that the calcium-antagonist diltiazem enhances the 'in vitro' bactericidal action of the aminoglycoside gentamicin, especially against Gram-positive bacteria. To verify if a non-specific interaction of these two drugs with biomembranes may play a role in their synergic effect on bacterial cells, we have studied the effect of exposure to gentamicin, in the absence or presence of diltiazem, on the release of carboxyfluorescein (CF) trapped in phosphatidylcholine (PC) unilamellar vesicles (LUVs) used as model membranes. A significant leakage of trapped CF from PC LUVs was registered when liposomes were treated with gentamicin and diltiazem together, employed at doses (50 and 100 microg/ml, respectively) unable to affect CF release if applied alone; the combined effect of gentamicin and diltiazem was synergic and not cumulative. The present findings demonstrate that the simultaneous exposure to gentamicin and diltiazem may induce significant alterations in the permeability of phospholipid membranes and, so, very likely, in functional properties of bacterial membranes, targets of their action.

In vitro antibacterial activity of some aliphatic aldehydes from Olea europaea L

In the present paper we report the 'in vitro' activity of eight aliphatic long-chain aldehydes from olive flavor (hexanal, nonanal, (E)-2-hexenal, (E)-2-eptenal, (E)-2-octenal, (E)-2-nonenal, (E)-2-decenal and (E,E)-2,4-decadienal) against a number of standard and freshly isolated bacterial strains that may be causal agents of human intestinal and respiratory tract infections. The saturated aldehydes characterized in the present study do not exhibit significant antibacterial activity, while the alpha,beta-unsaturated aldehydes have a broad antimicrobial spectrum and show similar activity against Gram-positive and Gram-negative microorganisms. The effectiveness of the aldehydes under investigation seems to depend not only on the presence of the alpha,beta-double bond, but also on the chain length from the enal group and on the microorganism tested.

Fetal vesicoureteral reflux: neonatal findings and follow-up study

To examine features of primary vesicoureteric reflux (VUR) at birth following prenatal hydronephrosis and to describe the course of congenital damage in the first two years of life. We reviewed the records of 382 patients with prenatally diagnosed dilated urinary tracts seen during a 15-years period. When fetal hydronephrosis was confirmed at birth, voiding cystography was performed. If a VUR was diagnosed dimercaptosuccinic acid (DMSA) renography, at 1 month of age, was also performed. Cystography and DMSA renography were repeated and 1 and 2 years of age. Of 382 patients with prenatal hydronephrosis, 68 (17.8%) had primary VUR (50 male and 18 female, M:F = 3:1). VUR was unilateral in 24 patients and bilateral in 44 for a total of 112 refluxing renal units (RRUs). High-grade VUR (grade > or = 4) was found in 70 (62.5%) RRUs, and 60 (85.7%) were boys. Grade V reflux was observed in 96.5% of males. At birth, 22 (20%) RRUs had moderate impairment of renal function. In 12 (10%) RRUs (grade > or = 4) was demonstrated by a severe decrease in renal function. In all cases no focal scarring was noted. Eight infants (all males), with grade 5 degrees VUR, in the first six months of life had surgical treatment. The majority of the RRUs (110/112 = 89%) were followed medically. Mild reflux (grade I-III) had resolved in 81% RRUs, severe reflux (grade > or = 4) had resolved in 38% RRUs. Serial renal scans during the follow-up showed no progression of renal damage. VUR diagnosed at birth on prenatal ultrasonography is associated with congenital damage, with males affected more often than females. In patients without infection, after two years, modification of renal function or renal scars are very rarely observed.

[Inhibin B immunocytochemistry for the prognosis assessment of undescended testis damage in children]

Inhibin B immunocytochemistry of both the alpha- and beta-subunits was studied in testicular biopsies from 18 prepubertal and postpubertal patients, with unilateral or bilateral cryptorchism. The present investigation was carried out to seek any prognostic significance for the expected fertility of such subjects in adulthood. All samples were also evaluated by histological and morphometric assessments, according a 1-6 grading sy-stem. In this way, the individual testicular changes were scored by quantitating tubular and germ cell hypoplasia, Sertoli cell hyperplasia, and peritubular fibrosis, where present. The results showed that in bilateral maldescended testes an unexpected expression often occurred of inhibin B beta-subunit in Sertoli cells, while inhibin B alpha-subunit there did not, denoting an early developmental arrest of the testis. It co-related with the high grade testicular damages, as a poor predictor of spermatogenesis. Unlike, unilateral retained testes mainly expressed inhibin B alpha-subunit, irrespective of tubular changes. In the latter instance, different pathogenetic factors of imbalanced testicular regulation can be perspected, other than the Inhibin-Activin system.

Apoptotic cell death and impairment of L-type voltage-sensitive calcium channel activity in rat cerebellar granule cells treated with the prion protein fragment 106-126

Prion diseases are neurodegenerative pathologies characterized by the accumulation, in the brain, of altered forms of the prion protein (PrP), named PrP(Sc). A synthetic peptide homologous to residues 106-126 of PrP (PrP106-126) was reported to maintain the neurodegenerative characteristics of PrP(Sc). We investigated the intracellular mechanisms involved in PrP106-126-dependent degeneration of primary cultures of cerebellar granule neurons. Prolonged exposure of such neurons to PrP106-126 induced apoptotic cell death. The L-type voltage-sensitive calcium channel blocker nicardipine reproduced this effect, suggesting that blockade of Ca(2+) entry through this class of calcium channels may be responsible for the granule cell degeneration. Microfluorometric analysis showed that PrP106-126 caused a reduction in cytosolic calcium levels, elicited by depolarizing K(+) concentrations in these neurons. Electrophysiological studies demonstrated that PrP106-126 and nicardipine selectively reduce the L-type calcium channel current. These data demonstrate that PrP106-126 alters the activity of L-type voltage-sensitive calcium channels in rat cerebellar granule cells and suggest that this phenomenon is related to the cell death induced by the peptide.

Intracellular mechanisms mediating the neuronal death and astrogliosis induced by the prion protein fragment 106-126

Prion encephalopathies include fatal diseases of the central nervous system of men and animals characterized by nerve cell loss, glial proliferation and deposition of amyloid fibrils into the brain. During these diseases a cellular glycoprotein (the prion protein, PrP(C)) is converted, through a not yet completely clear mechanism, in an altered isoform (the prion scrapie, PrP(Sc)) that accumulates within the brain tissue by virtue of its resistance to the intracellular catabolism. PrP(Sc) is believed to be responsible for the neuronal loss that is observed in the prion disease. The PrP 106-126, a synthetic peptide that has been obtained from the amyloidogenic portion of the prion protein, represents a suitable model for studying the pathogenic role of the PrP(Sc), retaining, in vitro, some characteristics of the entire protein, such as the capability to aggregate in fibrils, and the neurotoxicity. In this work we present the results we have recently obtained regarding the action of the PrP 106-126 in different cellular models. We report that the PrP 106-126 induces proliferation of cortical astrocytes, as well as degeneration of primary cultures of cortical neurons or of neuroectodermal stable cell lines (GH(3) cells). In particular, these two opposite effects are mediated by the same attitude of the peptide to interact with the L-type calcium channels: in the astrocytes, the activity of these channels seems to be activated by PrP 106-126, while, in the cortical neurons and in the GH(3) cells, the same treatment causes a blockade of these channels causing a toxic effect.

A case of non-immune hydrops fetalis with congenital cystic adenomatoid malformation of the left lung in a twin

Hydrops fetalis is a rare condition that occurs in one out of every 1,400-4,000 pregnancies. There are two types, immune and non-immune. It can be caused by a maternal-fetal incompatibility due to the Rh factor or, more rarely, the Kell factor or due to other antigens to red corpuscles. Non-immune types of hydrops have a complex multiform pathogenesis and in 50% of the cases they are of idiopathic nature. The causes that could determine non-immune hydrops are manifold and in 50% of the cases they are of an idiopathic nature. Independently of the clinical condition, the presented case could be classified in those forms of pathogenesis in which there is the presence of a congenital cystic adenomatoid malformation (CAM), not encountered in the fetal ultrasound performed at the sixteenth week of pregnancy. The particularity of our case is due to the association of the fetal hydrops of the CAM type in only one of the two twins. The presented case is classified in those forms of hydrops that are expressed with a clinical trend towards a worse prognosis, characterized by the intrauterine death of the fetus or the birth of a hydropic fetus that does not survive because of respiratory insufficiency and cardiocirculatory collapse.

Somatostatin receptor 1 (SSTR1)-mediated inhibition of cell proliferation correlates with the activation of the MAP kinase cascade: role of the phosphotyrosine phosphatase SHP-2

The mitogen activated protein (MAP) kinase cascade represents one of the major regulator of cell growth by hormones and growth factors. However, although the activation of this intracellular pathway has been often regarded as mediator of cell proliferation, in many cell types the increase in MAP kinase (also called extra-cellular signal regulated kinase: ERK) activity may result in cell growth arrest, depending on the length or the intensity of the stimulation. In this review we examine recent data concerning the effects of somatostatin on the MAP kinase cascade through one of its major receptor subtype, the somatostatin receptor 1 (SSTR1), stably expressed in CHO-K1 cells. Somatostatin inhibits the proliferative effects of basic FGF (bFGF) in CHO-SSTR1 cell line. However, in these cells, somatostatin robustly activates the MAP kinase and augments bFGF-induced stimulation of ERK. We show that the activation of ERK via SSTR1 is mediated by the betagamma subunit of a pertussis toxin-sensitive G-protein and requires both the small G protein Ras and the serine/threonine kinase Raf-1. Moreover the phosphatidyl inositol-3kinase and the cytosolic tyrosine kinase c-src participate in the signal transduction regulated by SSTRI to activate ERK, as well as it is involved the protein tyrosine phosphatase (PTP) SHP-2. Previous studies have suggested that somatostatin-stimulated PTP activity mediates the growth inhibitory actions of somatostatin, in CHO-SSTR1 cells. Thus, the activation of SHP-2 by SSTR1 may mediate the antiproliferative activity of somatostatin. SHP-2 may. in turn, regulate the activity of kinases upstream of ERK that require tyrosine dephosphorylation to be activated, such as c-src. Finally, the synergism between somatostatin and bFGF in the activation of ERK results in an increased expression of the cyclin-dependent kinase inhibitor p21cip/WAF1 as molecular effector of the antiproliferative activity of somatostatin.

Prolonged treatment with alpha-glycerylphosphorylethanolamine facilitates the acquisition of an active avoidance behavior and selectively increases neuronal signal transduction in rats

The effects of alpha-glycerylphosphorylethanolamine on both behavioral and neurochemical parameters were studied in adult rats. Daily administration of the drug caused a significant improvement in the behavioral performance of rats in the active avoidance conditioning test. This effect was observed after about ten days of treatment, and lasted until the end of the experiment (fifteen days). The improvement in this memory-related behavioral test correlated with a facilitation of both muscarinic and beta-adrenergic stimulation of brain adenylyl cyclase activity. Conversely, no changes were observed in basal or forskolin-induced stimulation of cAMP production, suggesting that the alpha-glycerylphosphorylethanolamine effects were not directed on the enzyme itself, but might favor the coupling between receptors, G proteins and effectors. Similar results were observed on the muscarinic stimulation of inositol phosphate accumulation although, in this case, a potentiation of the basal activity also occurred. In conclusion, our data indicate that daily treatment with alpha-glycerylphosphorylethanolamine improves the learning and memory processes in the rat, evaluated using the active avoidance conditioning test. Furthermore, the subchronic administration of this compound is able to enhance receptor-mediated neuronal signal transduction, namely cAMP and inositol phosphate production. These neurochemical modifications may represent, at least in part, the molecular mechanisms of action of the drug.

Somatostatin and its analog lanreotide inhibit the proliferation of dispersed human non-functioning pituitary adenoma cells in vitro

OBJECTIVE

Somatostatin is a powerful inhibitor of hormone secretion and cell proliferation. Treatment with somatostatin analogs in humans causes a reduction in size and secretory activity of some endocrine tumors, including somatotropic pituitary adenomas. Less studied are the effects of somatostatin agonists on non-functioning pituitary adenomas (NFPAs). In this study we characterized the effects of somatostatin and its analog lanreotide on the proliferation of NFPAs in vitro and the intracellular mechanisms involved.

DESIGN

Twenty-three NFPA post-surgical specimens were analyzed for somatostatin receptor (SSTR) expression and 12 of them were cultured in vitro to study somatostatin's effects on cell proliferation, assessed by means of [(3)H]thymidine uptake, and the intracellular signaling.

RESULTS

One or more SSTR subtypes were expressed in 90% of the adenomas tested. Somatostatin and lanreotide treatment inhibited phorbol myristate acetate (PMA)-induced cell proliferation. Vanadate pretreatment reversed somatostatin and lanreotide inhibition of PMA-induced DNA synthesis suggesting an involvement of tyrosine phosphatase in this effect. In the only adenoma tested, somatostatin directly induced a tyrosine phosphatase activity. Somatostatin and lanreotide caused also a significant inhibition of voltage-sensitive calcium channel activity induced by 40mmol/l K(+) depolarization in microfluorimetric analysis.

CONCLUSIONS

These data show that somatostatin and lanreotide inhibit human NFPA cell proliferation in vitro, and suggest that activation of tyrosine phosphatases and inhibition of the activity of voltage-dependent calcium channels may represent intracellular signals mediating this effect.

Serotype and phage type distribution of salmonellas from human and non-human sources in Italy in the period 1973-1995

According to the data collected at the Rome-based National Reference Centre for Enterobacteria, 266,547 Salmonella strains isolated from human sources (226,513) and from non human sources (40,034) were characterised in Italy during the period 1973-1995. The serotype of all isolates, and the antibiotype and phage type of selected isolates were determined. Human-source isolations grew from 4372 in 1973 to 12,310 in 1995: non-human source isolations, from 339 in 1973 to 3459 in 1995. Salm. Typhimurium ranked first in the list of the most common serotypes isolated from both sources in the period 1973-1988 except in the years 1975 and 1976 when it was overtaken by Salm. Wien. Since 1983 Salm. Enteritidis has been among the top ten isolates from animals, and ranked first in the list of isolates from humans in 1988 and from non human sources in 1991. During the last years the number of multidrug-resistant strains, mostly belonging to phage types 104 and 193 of Salm. Typhimurium has been rising. Salmonella strains have also been isolated from numerous extraintestinal infections, almost exclusively caused by Salm. Enteritidis and Typhimurium.

Active involvement of catalase during hemolytic crises of favism

The endemic occurrence of favism in certain Mediterranean regions provided an investigative opportunity for testing in vivo the validity of claims as to the role of catalase in protecting human erythrocytes against peroxidative injury. Reduced activity of catalase was found in the erythrocytes of six boys who were deficient in erythrocytic glucose-6-phosphate dehydrogenase (G6PD) and who were studied while suffering hemolysis after ingesting fava beans. Activity of catalase was further reduced when their red blood cells were incubated with aminotriazole. In contrast, minimal reduction of catalase activity was found, both with and without incubation with aminotriazole, in erythrocytes of a G6PD-deficient boy who had ingested fava beans 7 days earlier and in erythrocytes of seven G6PD-deficient men with a past history of favism. These results confirmed earlier studies in vitro indicating that catalase is a major disposer of hydrogen peroxide in human erythrocytes and, like the glutathione peroxidase/reductase pathway, is dependent on the availability of reduced nicotinamide adenine dinucleotide phosphate (NADPH). The effect of divicine on purified catalase and on the catalase of intact G6PD-deficient erythrocytes was similar to the previously demonstrated effect on catalase of a known system for generating hydrogen peroxide. This effect of divicine strengthens earlier arguments that divicine is the toxic peroxidative component of fava beans.

Predominant role of catalase in the disposal of hydrogen peroxide within human erythrocytes

Purified enzymes were mixed to form a cell-free system that simulated the conditions for removal of hydrogen peroxide within human erythrocytes. Human glutathione peroxidase disposed of hydrogen peroxide (H2O2) at a rate that was only 17% of the rate at which human catalase simultaneously removed hydrogen peroxide. The relative rates observed were in agreement with the relative rates predicted from the kinetic constants of the two enzymes. These results confirm two earlier studies on intact erythrocytes, which refuted the notion that glutathione peroxidase is the primary enzyme for removal of hydrogen peroxide within erythrocytes. The present findings differ from the results with intact cells, however, in showing that glutathione peroxidase accounts for even less than 50% of the removal of hydrogen peroxide. A means is proposed for calculating the relative contribution of glutathione peroxidase and catalase in other cells and species. The present results raise the possibility that the major function of glutathione peroxidase may be the disposal of organic peroxides rather than the removal of hydrogen peroxide.

Reducing ischemia-reperfusion injury in rat island groin flaps by dexamethasone and BW755C

Despite the known effectiveness of anti-inflammatory therapy in reducing reperfusion injury, no studies to date involve the use of anti-inflammatory therapy in reducing ischemia-reperfusion injury in fasciocutaneous flaps. Dexamethasone (a phospholipase A2 inhibitor) and specific cyclooxygenase and lipoxygenase inhibitors (indomethacin and BW755C) were administered to rats with ischemic island groin (fasciocutaneous) flaps. Significant improvement in ischemic flap survival was found with dexamethasone and BW755C. The mode of action of dexamethasone was not specifically investigated in our study; however, it may suppress neutrophil function and reduce ischemia-reperfusion injury in its shared ability with BW755C to reduce the formation of leukotrienes. Dexamethasone could be applied in the clinical setting to reduce ischemic flap loss by attenuating the systemic inflammatory response to reperfused ischemic-damaged tissue.

Reducing ischemia-reperfusion injury in rat island groin flaps using dexamethasone

Reducing reperfusion injury is effective in reducing flap loss after prolonged ischemia. Anti-inflammatory therapy reduces reperfusion injury in canine cardiac muscle and ex vivo rat cremaster muscle; however, to date, there are no studies involving the use of anti-inflammatory agents in ischemic skin flaps. This study was designed to assess the effects of dexamethasone and indomethacin on the viability of rat island groin flaps subjected to 10 hours of ischemia. The ischemic control and the treatment group flaps were subjected to 10 hours of ischemia by clamping the inferior epigastric vascular pedicle. The treatment groups received either intravenous dexamethasone or intravenous indomethacin after the flap vascular pedicles were clamped. Our results showed significant improvement (p < 0.05, Fisher's exact test) in ischemic flap survival using dexamethasone. The specific mode of action of dexamethasone was not investigated; however, its anti-inflammatory effects were most likely responsible for the improvement of flap survival by suppressing the circulating neutrophil and decreasing reperfusion injury. Dexamethasone is easily available for clinical use, and its use should be considered in cases of prolonged ischemia in skin flaps.

Interface analysis of hydroxyapatite-coated implants in a human vascularized iliac bone graft

This case report demonstrates the interface histology of hydroxyapatite-coated dental implants placed in a human vascularized iliac bone graft. Microscopic evaluation found a direct contact of lamellar bone to the implant surface even in areas of loose trabeculation. The hydroxyapatite coating was intact, with no evidence of resorption. This study appears to show that the healing response to hydroxyapatite-coated implants placed in vascularized bone grafts is similar to previously reported findings in nongrafted sites.