Veralipride administered in combination with raloxifene decreases hot flushes and improves bone density in early postmenopausal women

We evaluated the administration of raloxifene and veralipride in postmenopausal women with high osteoporosis risk and hot flushes in whom hormone replacement therapy (HRT) was contraindicated. A group of early postmenopausal women (n = 29) (mean age 51.8 +/- 4.1), complaining of severe vasomotor symptoms and with a bone mineral density (BMD) T-score between -1.5 and -2.5 were evaluated. They were randomly assigned to two treatment groups: raloxfene (60 mg/day) continuously in association with veralipride (100 mg/day) on alternate days (n = 17); or on alternate months (n = 12). BMD, serum prolactin concentration and endometrial thickness were assessed at baseline and after 6 months of therapy. Kupperman Index and hot flushes were assessed before and after 3 and 6 months of therapy. BMD was significantly higher at the end of therapy with an increase of 1.1%. Kupperman Index was significantly reduced after 3 months and a further decrease at 6 months was observed with both protocols. Both treatments led to a significant reduction of hot flushes after 3 and 6 months. No signifcant changes of prolactin levels were observed in either protocol. We found that the combined raloxifene-veralipride treatment, both every other day and every other month, led to a significant improvement in bone density and was effective in hot flushes and other menopause-associated symptoms. These protocols could represent a new way to administer raloxifene in early postmenopausal women at high osteoporosis risk with HRT contraindication.

Pelvic exenterative procedures for locally advanced or recurrent colorectal carcinoma in a community hospital

BACKGROUND

We describe our experience with exenterative pelvic surgery for colorectal cancer in a small community hospital.

METHODS

We retrospectively evaluated 26 consecutive patients (14 women) with locally advanced (n=16) or recurrent (n=10) colorectal adenocarcinomas who underwent pelvic exenterations between August 1990 and December 2001 in our service.

RESULTS

Seventeen patients had posterior pelvic exenteration (PPE), eight had total pelvic exenteration (TPE) and one had TPE with internal hemipelvectomy. Major morbidity occurred in 12 patients (46%), causing 3 deaths (11%) in the immediate postoperative period. Fourteen of 23 patients who survived the immediate postoperative period have relapsed (61%). At a median follow-up of 42 months, the 5-year survival is 38%.

CONCLUSION

Pelvic exenterative procedures can be offered to patients with bulky or recurrent colorectal carcinomas with adequate results and satisfactory palliation, even in a community setting.

Interleukin-1β up-regulates nitrite production: effects on ovarian function

We have previously reported that Interleukin-1beta (IL-1beta) affects ovarian function in the rat, modulating prostaglandin and progesterone (P) production. As IL-1beta effects were associated to nitric oxide (NO) synthesis, in the present work we have further examined the role of ovarian NOS-system, in IL-1beta antisteroidogenic action. Mid-luteal explants from rats were incubated for 4 h in the presence of IL-1beta (1-35 ng/ml)-alone or in combination with NOS-inhibitors-and then assayed for P and nitrite production. IL-1beta treatment reduced P levels in a dose-dependent manner, returning to basal levels at 35 ng/ml. This reduction in steroid synthesis was paralleled by a dose-dependent increase in nitrite levels, reaching a maximum at 25 ng/ml but without effect at 35 ng/ml. L-Arginine (1 and 2 mM) was able to mimic IL-1beta actions and the NOS blocker L-Nitro-Arginin-Methyl Ester reverted these effects. Moreover, the selective iNOS inhibitor, 1400 W, completely abolished IL-1beta antisteroidogenic effect, therefore confirming the dependence of IL-1beta action upon iNOS activation. Finally, IL-1beta did not affect eNOS expression but up-regulated iNOS mRNA and protein levels. Our results suggest an interaction between IL-1beta and the NOS-system. Thus, we may conclude that in the rat iNOS-derived NO production, induced by IL-1beta, affects ovarian P biosynthesis and hence NO may be a major effector molecule of ovarian IL-1 system.

Ultrastructure of acidic polysaccharides from the cell walls of brown algae

We have studied the ultrastructure of acidic polysaccharides from the cell walls of brown algae using a variety of electron microscopy techniques. Polysaccharides from Padina gymnospora present self assembled structures, forming trabecular patterns. Purified fractions constituted by alginic acid and sulfated fucan also form well-organized ultrastructures, but the pattern of organization varies depending on the polysaccharide species. Alginic acid presents sponge-like structures. Sulfated fucan exhibits particles with polygonal forms with a polycrystalline structure. These particles are in fact constituted by sulfated fucan molecules since they are recognized by a lectin specific for alpha-l-fucosyl residues. X-ray microanalysis reveal that S is a constituent element, as expected for sulfated groups. Finally, an exhaustive purified sulfated fucan shows the same ultrastructure formed by polygonal forms. Furthermore, elemental analyses of acidic polysaccharides indicate that they retain Zn, when algae were collected from a contaminated area. This observation is supported by direct quantification of heavy metal in the biomass and also in the solubilized polysaccharides compared with the algae from a non-contaminated site. We conclude that these molecules have specific ultrastructure and elemental composition; and act as metal binder for the nucleation and precipitation of heavy metals when the algae are exposed to a metal contaminated environment.

Additive pro-oxidative effects of methylmercury and ebselen in liver from suckling rat pups

Oxidative stress has been pointed as an important molecular mechanism for liver injury in methylmercury (MeHg) poisoning. Ebselen, a seleno-organic compound that possesses anti-oxidant properties, is a useful therapeutic agent used in clinical situations involving oxidative stress. Here, we examined the possible in vivo protective effect of ebselen against the pro-oxidative effects of MeHg in liver from suckling rat pups. The effects of MeHg exposure (subcutaneous injections of methylmercury chloride: 2 mg/kg) on the hepatic levels of thiobarbituric acid reactive substances (TBARS) and non-ptotein thiols (NPSH), and on liver glutathione peroxidase (GSHPx) activity, as well as the possible antagonist effect of ebselen (10 mg/kg; subcutaneously) against MeHg effects, were evaluated during the post-natal period. In addition, the possible in vitro interaction between ebselen, glutathione (GSH) and MeHg was investigated by light/UV spectroscopy, with particular attention to the formation of complexes involving ebselen selenol intermediate and MeHg. After in vivo exposure, MeHg and ebselen alone increased hepatic TBARS levels. Moreover, simultaneous treatment with both compounds caused a higher increase in hepatic TBARS levels when compared to the treatments with individual compounds. Liver NPSH decreased after treatments with MeHg and ebselen alone. A significant negative correlation between hepatic TBARS and NPSH was observed. MeHg alone decreased liver GSHPx activity and ebselen, which did not affect this variable per se, reverted this inhibitory effect of MeHg. Light/UV spectroscopy showed that ebselen and GSH form a chemical intermediate that regenerates ebselen after MeHg addition. The presented results show that ebselen abolished the MeHg-induced inhibition on liver GSHPx activity, but did not prevent the oxidative effects of MeHg on liver lipids and NPSH. MeHg affects the in vitro interaction between ebselen and GSH and this phenomenon seems to be responsible for its inhibitory effect toward thiol-peroxidase activity. Additionally, ebselen presents pro-oxidative effects on rat liver, pointing to thiol depletion as a molecular mechanism related to ebselen-induced hepatotoxicity.

Effects of in vivo administration of epidermal growth factor (EGF) on uterine contractility, prostaglandin production and timing of parturition in rats

Prostaglandins synthesized by cyclooxygenases elicit uterine contractions during labour. Nitric oxide synthases (NOS) produce nitric oxide (NO), which maintains uterine quiescence during pregnancy. Epidermal growth factor (EGF) interacts with prostaglandins and NO in many biological systems. The aim of this work was to study the effect of the in vivo administration of EGF on uterine contractility, prostaglandin production and timing of parturition in rats. EGF was injected into the uterine lumen of pregnant rats on day 20, 21 or 22 of gestation. Intra-uterine administration of 500 ng EGF on day 21 of gestation delayed parturition for 18 h compared with control rats. Administration of EGF was able to: (i) reduce cyclooxygenase expression in the uterus (determined by western blot analysis) and production of prostaglandins by the uterus (evaluated by conversion of [(14)C]arachidonate to labelled prostaglandins); (ii) decrease prostaglandin concentrations in amniotic fluid (radioimmunoassay); (iii) increase NO production (evaluated by conversion of [(14)C]arginine into [(14)C]citrulline); (iv) increase serum progesterone concentrations to more than control concentrations (P<0.05; radioimmunoassay); and (v) reduce the amplitude of the uterine contractions. The overall effect was a delay in the onset of delivery. This in vivo effect raises the question of whether exogenous EGF plays a role in the initiation of parturition.

Epidermal growth factor modulation of prostaglandins and nitrite biosynthesis in rat fetal membranes

The production of prostaglandins (PGs) and nitric oxide (NO) by amnion tissue may play a significant role in parturition. It is thought that epidermal growth factor (EGF) may be one of the fetal signals that governs the initiation of labor. The aim of the present study was to investigate the effect of EGF in vivo on the PGs and nitrite production of rat fetal membranes. We have evaluated the regulation of PGs and nitrite production in rat fetal membranes ex vivo. The intra-uterine administration of EGF 500 ng in day 21 of pregnancy induced increases in PGE(2) (P<0.001) and PGF(2alpha) (P<0.01) compared to the control fetal membranes from pregnant rats on day 22. Also, this dose of EGF diminished nitrate production significantly (P<0.01). We found that fetal membranes at term (days 18-22 of gestation) expressed EGF-R. The NO donor, nitroprussiate 300 and 600 microM, elicited an inhibitory effect on the PGE(2) and PGF(2alpha) stimulated synthesis. On the other hand, indomethacin 10(-6) and 10(-7)M, a non-selective cyclooxygenase inhibitor, reverted the inhibitory effect exerted by EGF. Hence, rat fetal membranes were found to express epidermal growth factor receptors and, under the effect of EGF, PGs and nitrites production pathways interact probably to prevent a toxic effect caused by an exacerbated synthesis of these mediators.

Characterization of a bovine collagen–hydroxyapatite composite scaffold for bone tissue engineering

Different biomaterials have been used as scaffolds for bone tissue engineering. Here we characterize a biomaterial composed of sintered (1100 degrees C) and powdered hydroxyapatite (HA) and type I collagen (Coll), both of bovine origin, designed for osteoconductive and osteoinductive scaffolds. Coll/HA proportions were 1/2.6 and 1/1 (wet weight), and particles sizes varied from 200 to 400 microm. Vv (volume density) and Sv (surface to volume density) for the HA particles in the composite ranged from 0.48 +/- 0.06 to 0.55 +/- 0.02 and 5.090 +/- 0.545 to 6.366 +/- 0.289 microm(-1), respectively. Due to the relatively small changes in Vv and Sv, a macroporosity could be characterized for the biocomposite. X-ray diffraction and infrared spectroscopy showed that the sintered bone was composed essentially of HA with minimum additional groups such as surface calcium hydroxide, surface and crystal water, free carbon dioxide and possibly brushite. Mass spectrometry detected carbonates at A and B sites of HA, and weakly bound to the structure. Human osteoblasts adhered and spread on both the HA particle surface and the collagen fibers, which seemed to guide cells between adjacent particles. The biocomposite studied has several characteristics considered as ideal for its use as a scaffold for osteoconduction and osteoinduction.

Effects of cyclooxygenase inhibitor pretreatment on nitric oxide production, nNOS and iNOS expression in rat cerebellum

1. The therapeutic effect of nonsteroidal anti-inflammatory drugs (NSAIDs) is thought to be due mainly to its inhibition of cyclooxygenase (COX) enzymes, but there is a growing body of research that now demonstrates a variety of NSAIDs effects on cellular signal transduction pathways other than those involving prostaglandins. 2. Nitric oxide (NO) as a free radical and an agent that gives rise to highly toxic oxidants (peroxynitrile, nitric dioxide, nitron ion), becomes a cause of neuronal damage and death in some brain lesions such as Parkinson and Alzheimer disease, and Huntington's chorea. 3. In the present study, the in vivo effect of three NSAIDs (lysine clonixinate (LC), indomethacine (INDO) and meloxicam (MELO)) on NO production and nitric oxide synthase expression in rat cerebellar slices was analysed. Rats were treated with (a) saline, (b) lipopolysaccharide (LPS) (5 mg kg(-1), i.p.), (c) saline in combination with different doses of NSAIDs and (d) LPS in combination with different doses of NSAIDs and then killed 6 h after treatment. 4. NO synthesis, evaluated by Bred and Snyder technique, was increased by LPS. This augmentation was inhibited by coadministration of the three NSAIDs assayed. None of the NSAIDs tested was able to modify control NO synthesis. 5. Expression of iNOS and neural NOS (nNOS) was detected by Western blotting in control and LPS-treated rats. LC and INDO, but not MELO, were able to inhibit the expression of these enzymes. 6. Therefore, reduction of iNOS and nNOS levels in cerebellum may explain, in part, the anti-inflammatory effect of these NSAIDs and may also have importance in the prevention of NO-mediated neuronal injury.

[Extemporaneous examination of the sentinel lymph node in breast cancer: is the glass half full or half empty?]

Intra-operative examination of sentinel LN is controversial. Concordance with definitive exam of SLN in this series was 81%, though only 54% of positive cases were diagnosed. Micrometastases and ITC were usually lost intraoperatively, accounting for 14% of cases. Frozen section and touch prep of the SLN were approximately equivalent. The latter has the advantage of preserving tissue for step-analysis of SLN. The ultimate method of intraoperative analysis of SLN which can combine cost-effectiveness and accuracy needs to be determined.

Osteoporosis: still a typical complication of primary biliary cirrhosis?

BACKGROUND

Osteoporosis is a recognized complication of primary biliary cirrhosis but it has been suggested that its prevalence may overlap that observed among postmenopausal women.

AIM

To evaluate prevalence and risk factors of osteoporosis in primary biliary cirrhosis.

PATIENTS

A total of 133 female patients (age 53+/-10 years, menopausal status 70%, histological stage I-II 61%, portal hypertension 28%, Mayo Risk Score 4.11+/-0.59) were enrolled.

METHODS

Dual X-ray absorptiometry of the lumbar spine.

RESULTS

Mean bone mineral density, T and Z score were 0.861+/-0.160 g/cm2, -1.87+/-1.45 and -0.78+/-2.63, respectively. At multivariate analysis, bone mineral density was inversely correlated with age (p<0.05). Osteoporosis was present in 39/92 (41%) postmenopausal and 8/41 (20%) premenopausal patients. In the premenopausal group, osteoporosis was significantly correlated with serum albumin (p<0.05) and Mayo Risk score (p<0.005). No significant correlation was present in the postmenopausal group.

CONCLUSIONS

Despite the accepted wisdom that osteoporosis is a common complication of primary biliary cirrhosis, its frequency in post-menopausal patients overlaps that observed in the general population, but is much more frequent in premenopausal patients, where it appears to be related to severity of liver disease and cholestasis.

[Acute renal failure and thrombotic microangiopathy (TM)]

BACKGROUND

Thrombotic microangiopathy (TM) is a disorder characterized by fibrin formation and platelet aggregation in the small arteries and capillaries. Two main clinical settings are reported in association with this disorder: hemolitic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). Both conditions share common findings such as microangiopathic anemia and thrombocytopenia. HUS is more frequent in children and is mainly characterized by renal symptoms, whereas PTT is dominated by neurologic abnormalities. However, in many patients, the clinical distinction between HUS and PTT is not clear; therefore, some authors consider the two syndromes as manifestations of the same entity. In children, the most common cause of HUS is an enteric infection caused by cytotoxin-producing bacteria (mainly Escherichia coli with serotype O157:H7). This toxin--the Shiga toxin--can bind to glomerular endothelial cells and stimulate the production of cytokines and the secretion of von Willebrand factor (vWf). TM may be caused by drugs such as cyclosporin, tacrolimus, mytomicin C, ticlopidine, quinine, and oral contraceptives. It may be associated with disorders of pregnancy (severe pre-eclampsia and postpartum HUS) or with systemic disorders such as systemic lupus erythematosus (SLE), antiphospholipid syndrome, systemic sclerosis, and human immunodeficiency virus (HIV) infection. Abnormalities of the gene of complement factor H have been found in familial HUS and in some sporadic cases of HUS not associated with diarrhea. Factor H abnormalities induce an uncontrolled complement activation that can activate the coagulation cascade. In familial PTT, genetic abnormalities of the cleaving metalloproteinase of fWf ADAMTS 13 have been identified. In other patients with TTP, antibodies inhibiting this enzyme have been found. As a consequence of plasma ADAMTS 13 deficiency, unusually large vWf multimers are produced. This abnormality, in the presence of an increased shear stress, stimulates platelet adhesion and aggregation.

CONCLUSIONS

Knowledge of the type of causative abnormality is relevant to a therapeutic approach. Children with diarrheal HUS usually do not benefit from plasma infusion or exchange, whereas in patients with factor H or ADAMTS 13 deficiency procedures that include the administration of the lacking product and removal of the inhibiting or toxic factors, such as ultralarge vWfs, are mandatory. Potentially renal transplantation candidates should be screened for genetic defects to avoid the recurrence of TM in the graft.

Methylmercury increases glutamate release from brain synaptosomes and glutamate uptake by cortical slices from suckling rat pups: modulatory effect of ebselen

During the early postnatal period the brain is extremely sensitive to external agents. Here, we examined the effect of subcutaneous injections of methylmercury (MeHg; 2 mg/kg) during the suckling period (postnatal days [PND] 3-10, 3-17, or 3-24) on glutamate release from brain synaptosomal preparations and on glutamate uptake by brain cortical slices of rat pups. The possible antagonist effect of ebselen against MeHg effect was also examined at PND 24. MeHg increased the basal (but not K+-stimulated) glutamate release and glutamate uptake at PND 24. A strong tendency of increase in the basal glutamate release from synaptosomes (p= 0.088) was observed at PND 17. Ebselen, which did not affect glutamate release and uptake per se, prevented both effects of MeHg. This study indicates that (1) the effect of MeHg on glutamate release could be involved in its toxicity; (2) the increase in the glutamate uptake could represent a pathophysiological response to MeHg-induced glutamate release; (3) the inhibitory effect of ebselen on MeHg-induced glutamate release could be related to its reported neuroprotective effects.

Differences in umbilical cord blood units collected during cesarean section, before or after the delivery of the placenta

Umbilical cord blood is largely employed as an alternative source of stem cells in the treatment of hemato-oncological diseases. Current results show that the success rate of purified umbilical cord blood engraftment is comparable to that obtained using bone marrow, and it is directly related to the number of pluripotent stem cells transplanted. The technique of fetal blood collection varies among different umbilical cord blood banks. Many authors collect umbilical cord blood during vaginal delivery, after placental detachment, while others collect it while the placenta is still within the uterus. In a previous randomized trial, we showed a greater collection of umbilical cord blood before placental detachment during vaginal delivery. The present study was performed to determine whether umbilical cord blood collection before placental detachment (group A) during cesarean section is superior to that after placental delivery (group B) puncturing the umbilical vein once and using a closed bag system. To accomplish this, 47 pregnant women subjected to cesarean section were enrolled in the study. Twenty-one of them were allocated to group A, while the remaining 26 formed group B. The volume of umbilical cord blood collected from the patients of group A was greater than that collected from patients of group B. The cord blood volume collected was 90.7 +/- 6.0 versus 60.9 +/- 13.7 ml; the cord blood nucleated cell number was 10.1 +/- 1.2 x 10(8) vs. 7.1 +/- 0.8 x 10(8); and the mean cord blood CD34+ cell number was 20.0 +/- 6.0 x 10(5) vs. 16.4 +/- 2.4 x 10(5), respectively.

VLA-2 and VLA-5 cell adhesion molecules expression in CD34+ cells from umbilical cord blood and from bone marrow

BACKGROUND/AIMS

Umbilical cord blood contains a large number of early hematopoietic cells with high proliferating capacity, that has been used as an alternative to bone marrow transplantation. The aim of this study is to investigate the number of two cell adhesion molecules in cord blood and in bone marrow.

METHODS

We investigated two integrins, named VLA-2 and VLA-5 (Very Late Appearing Antigen), expressed in the surface of CD34+ cells. The CD34+ cells, isolated with MACS CD34+ isolation kit, were labelled with the appropriate monoclonal antibodies.

RESULTS

Cell adhesion molecules showed highly expressed in both cord blood and bone marrow CD34+ cells.

CONCLUSION

There are no significant differences between the two sources of CD34+ populations.

Interaction among beta-endorphin, nitric oxide and prostaglandins during ovulation in rats

The aim of this study was to investigate the relationship between beta-endorphin and nitric oxide (NO) during the ovulatory process in rats. Immature rats were treated with equine chorionic gonadotrophin-hCG to induce ovulation. An intrabursal injection of beta-endorphin stimulated nitric oxide synthase (NOS) activity. This effect was completely reversed when naltrexone was co-injected with beta-endorphin. The stimulatory action of beta-endorphin on NOS activity was studied to determine whether it was exerted via prostaglandins. Treatment with prostaglandin E(2) (PGE(2)) completely reversed the beta-endorphin-induced stimulation of NOS activity. Moreover, intrabursal injection of meloxicam, an inhibitor of cyclooxygenase 2, increased NOS activity, but this effect was not altered by co-injection with beta-endorphin. The presence of both endothelial NOS (eNOS) and inducible NOS (iNOS) in the ovary at 10 h after hCG treatment was studied by western blot analysis. Local administration of beta-endorphin inhibited the expression of eNOS protein, whereas expression of iNOS protein was not detectable. Ovarian beta-endorphin content was diminished at 10 h after hCG injection. Treatment with prostaglandin synthesis inhibitors in vivo augmented the ovarian beta-endorphin content. In conclusion, these results indicate that beta-endorphin stimulates the activity of ovarian NOS indirectly by inhibiting prostaglandin production.

Crosstalk between nitric oxide synthase and cyclooxygenase metabolites in the estrogenized rat uterus

In the present study, we investigated the effect of nitric oxide (NO) and prostaglandins (PGs) on the production of arachidonate and L-arginine metabolites. We found that in the estrogenized rat uterus lipopolysaccharide (LPS) 5mg/kg induced NO and PGs synthesis simultaneously. The uteri were incubated with different doses of an NO donor: NP 300 and 600 microM. The results indicate that both doses of NP produce a significant increase (P<0.01) in all prostanoids evaluated. The stimulatory effect was completely reversed by the addition of 2 microg/ml of hemoglobin (Hb), an NO scavenger. However, NOS inhibitor, N(G)-L-monomethyl arginine had no effect on basal prostanoid production. We also studied NO synthesis in the presence of different PGs concentration. We found that PGF(2alpha) and PGD(2) were capable of reversing LPS stimulation on NO synthesis (P<0.05), in all the doses evaluated. On the other hand, PGE(2) 10(-10) and 10(-9)M potentated LPS effect (P<0.001). These results suggest that in the estrogenized rat uterus, the synthesis of cyclooxygenase metabolites is positively regulated by NO, while NO synthesis regulation depends on the PGs evaluated.

Mechanisms of the inhibitory effects of selenium and mercury on the activity of delta-aminolevulinate dehydratase from mouse liver, kidney and brain

Mercury is known to interact with selenite and when the two are co-administered, one reduces the toxicity of the other. The main goal of this study was to investigate the simultaneous in vitro effects of sodium selenite (Se(4+)) and mercuric chloride (Hg(2+)) on the activity of hepatic, renal and cerebral delta-aminolevulinate dehydratase (delta-ALA-D) of adult male mice (Swiss albino). Hg(2+) inhibited delta-ALA-D from tissue supernatants and the IC(50) values for hepatic, renal and cerebral enzyme inhibition were 38+/-4.2, 67.5+/-4.3 and 46.2+/-3.7 microM, respectively. Se(4+) displayed a higher inhibitory action toward delta-ALA-D activity than Hg(2+). Simultaneous addition of Se(4+) and Hg(2+) to the delta-ALA-D assay increased the inhibition of the enzyme. Se(4+) and Hg(2+) oxidized total -SH groups from hepatic, renal and cerebral supernatants, although the effect of Se(4+) decreased in the presence of increasing concentrations of Hg(2+). The oxidation of -SH groups from a dithiol (DTT), a monothiol glutathione (GSH) and a protein (albumin) increased in the presence of Hg(2+). Only DTT was oxidized by Se(4+) and the oxidation decreased in the presence of Hg(2+), suggesting the formation of a chemical complex. This complex did not inhibit delta-ALA-D. These results suggest a similar inhibitory mechanism of Se(4+) and Hg(2+) on delta-ALA-D in which oxidation of sulfhydryl groups located at the active site of the enzyme is an essential step. Furthermore, decreasing oxidative effects of selenite on sulfhydryl groups from DTT in the presence of mercury are believed to occur as the result of the formation of an inactive ternary complex of the thiol-Hg-Se type, which does not inhibit delta-ALA-D.

Envelope ultrastructure of uncultured naturally occurring magnetotactic cocci

Magnetotactic bacteria are microorganisms that respond to magnetic fields. We studied the surface ultrastructure of uncultured magnetotactic cocci collected from a marine environment by transmission electron microscopy using freeze-fracture and freeze-etching. All bacteria revealed a Gram-negative cell wall. Many bacteria possessed extensive capsular material and a S-layer formed by particles arranged with hexagonal symmetry. No indication of a metal precipitation on the surface of these microorganisms was observed. Numerous membrane vesicles were observed on the surface of the bacteria. Flagella were organized in bundles originated in a depression on the surface of the cells. Occasionally, a close association of the flagella with the magnetosomes that remained attached to the replica was observed. Capsules and S-layers are common structures in magnetotactic cocci from natural sediments and may be involved in inhibition of metal precipitation on the cell surface or indirectly influence magnetotaxis.

Enzymatic, analytical and structural aspects of electron-dense granules in cells of Ucides cordatus (Crustacea, Decapoda) hepatopancreas

Electron-dense granules (EDGs) are singular structures found in the tissues of several vertebrate and invertebrate organisms. Two types of EDGs were observed in hepatopancreatic cells of the crab Ucides cordatus: (1) a non-mineralized EDG, found mainly inside vacuoles, which reacted positively to acid phosphatase and D-amino acid oxidase, possibly formed by degradation of lipid membranes, and (2) a mineralized EDG surrounded by endoplasmic reticulum membranes that gave a positive reaction for glucose-6-phosphatase. In this study we show the fine structure and composition of the mineralized EDGs using cytochemistry, analytical transmission electron microscopy and field-emission scanning electron microscopy. They are formed of microvesicle-like structures that are arranged in concentric spherical layers in the most mineralized portions of the granule. Analytical microscopy of mineralized EDGs indicated that they are composed of amorphous calcium-magnesium phosphate. Isolated EDGs treated with NaOCl lose several elements, including P, when compared with EDGs treated with deionized water. Removal of the organic matrix by NaOCl induced marked changes in the mineralized EDGs, showing that the organic matrix plays an important role in its elemental composition and structure.

Membrane vesicles in magnetotactic bacteria

Magnetotactic bacteria are microorganisms that respond to magnetic fields. We have studied the surface ultrastructure of Magnetospirillum magnetotacticum and uncultured magnetotactic bacteria from a marine environment using transmission electron microscopy and freeze-etching. Numerous membrane vesicles were observed on the surface of Magnetospirillum magnetotacticum bacteria. All uncultured magnetotactic bacteria presented membrane vesicles on their surface in addition to an extensive capsular material and an S-layer formed by particles arranged in a hexagonal symmetry. We did not observe any indication of electron-dense precipitation on the surface of these microorganisms. Our results indicate that membrane vesicles are a common characteristic of magnetotactic bacteria in natural sediments.

Steroid hormones augment nitric oxide synthase activity and expression in rat uterus

Nitric oxide (NO) is synthesized in a variety of tissues, including rat uterus, from L-arginine by NO synthase (NOS), of which there are three isoforms, namely neuronal, endothelial and inducible NOS (nNOS, eNOS and iNOS, respectively). Nitric oxide is an important regulator of the biology and physiology of the organs of the reproductive system, including the uterus. Some studies have shown increased variation in NO production and NOS expression during the oestrous cycle. However, the factors that regulate NO production in the uterus remain unclear. Therefore, in the present study, we investigated the effect of sex steroids on NOS expression and activity in the ovariectomized rat uterus. Ovariectomized rats received progesterone (4 mg per rat) or 17β-oestradiol (1 μg per rat). All rats were killed 18 h after treatment. Both progesterone and oestradiol were able to augment NOS activity. The effect of oestradiol was abolished by pre-incubation with 500 μM aminoguanidine, an iNOS inhibitor, or by coadministration of oestradiol with 3 mg kg−1 dexamethasone, but the effect of progesterone was not affected by these treatments. Uterine nNOS, eNOS and iNOS protein levels were assessed using Western blots. Ovariectomized rat uteri expressed iNOS and eNOS. Progesterone increased the expression of eNOS and iNOS, whereas oestradiol increased iNOS expression only. These results suggest that oestradiol and progesterone are involved in the regulation of NOS expression and activity during pregnancy and implantation in the rat.

Microstructure of Monoplacophora (Mollusca) shell examined by low-voltage field emission scanning electron and atomic force microscopy

The shell of Micropilina arntzi (Mollusca: Monoplacophora), a primitive molluscan class, was examined by using field emission scanning electron microscopy (FESEM) at low voltage and atomic force microscopy (AFM). The use of these two techniques allowed the observation of fine details of Micropilina arntzi shell and contributed to bring new features concerning the study of molluscan shell microtexture. Imaging with low-voltage FESEM provided well-defined edge contours of shell structures, while analyzing the sample with AFM gave information about the step height of stacked internal structures as well as the dimension of the particles present in their surface at a nanometric level. The shell microstructure of Monoplacophora species presents different patterns and may be a taxonomic implication in the systematic studies of the group.

Uterine bleeding pattern during low dosage Noretisterone acetate and 17-b-Estradiol treatment in postmenopausal patients

BACKGROUND

Recent years have been characterized by progressive optimization of postmenopausal hormonal replacement therapy. More physiological therapeutic protocols have been, in fact, proposed to control the possible symptomatology and to prevent the associated risks, with estro-progestinic compounds characterized by lower effective dosages and suitable for the single patient need. However this therapy is not widely accepted by the women from our country for the fears and the inconvenience raised around such side effects as abnormal uterine bleeding and spotting.

AIM

to obtain a good compliance and clinical benefits a continuous administration protocol of the hormonal replacement therapy, alternatively to the sequential one has been proposed.

METHODS

Our research group has been observing a sample of 42 patients for 12 months, taking oral 17-b-estradiol 1 mg/noretisterone 0.5 mg in continuous administration. All of them were aged from 42 to 63 years and had been in symptomatic menopause for at least 3 months. The characteristics, the onset and the trend of vaginal bleeding were registered in appropriate monthly diaries. Endometrial thickness was evaluated by transvaginal sonography before starting the administration, not exceeding 4 mm in all the women considered.

RESULTS

The incidence of bleeding (calculated as a percent of women who experienced a vaginal bleeding for al least a day during a menstrual cycle) was from 26% to 32% in the 1st trimester, reducing during the following months. At 6 months of therapy only 5% of women reported evident vaginal bleeding; at 12 months 90% of women complained with absence of bleeding or spotting. At 12 months no women showed an endometrial thickness over 6 mm.

CONCLUSIONS

This observational study suggests that the majority of treated patients proved to be positively responsive to the treatment and that the 17-b-estradiol 1 mg/noretisterone 0.5 mg association reduces the incidence of bleeding and spotting with a sufficient endometrial protection from hyperplasia.