Lead in the marine environment: concentrations and effects on invertebrates

Lead (Pb) is a non-essential metal naturally present in the environment and often complexed with other elements (e.g., copper, selenium, zinc). This metal has been used since ancient Egypt and its extraction has grown in the last centuries. It has been used until recently as a fuel additive and is currently used in the production of vehicle batteries, paint, and plumbing. Marine ecosystems are sinks of terrestrial contaminations; consequently, lead is detected in oceans and seas. Furthermore, lead is not biodegradable. It remains in soil, atmosphere, and water inducing multiple negative impacts on marine invertebrates (key species in trophic chain) disturbing ecological ecosystems. This review established our knowledge on lead accumulation and its effects on marine invertebrates (Annelida, Cnidaria, Crustacea, Echinodermata, and Mollusca). Lead may affect different stages of development from fertilization to larval development and can also lead to disturbance in reproduction and mortality. Furthermore, we discussed changes in the seawater chemistry due to Ocean Acidification, which can affect the solubility, speciation, and distribution of the lead, increasing potentially its toxicity to marine invertebrates.

Ultrasound-positive axillary lymph nodes in early breast cancer: can a patient subgroup avoid axillary lymph node dissection? A simple algorithm is suggested

INTRODUCTION

National UK guidelines suggest that axillary lymph node dissection (ALND) is no longer mandatory for selected early node-positive breast cancer patients. Our study aimed to identify patients with early breast cancer and ultrasound (USS)-positive axillary metastasis who possess low burden of axillary disease and can avoid ALND.

METHODS

We conducted a 5-year study of prospectively collected data of patients with clinically T1-2, N0 breast cancer and a positive USS-guided axillary biopsy. Primary outcome was involvement of 1-2 lymph nodes (low disease burden) or ≥3 lymph nodes (higher axillary disease) on final ALND histology. Tumour type, size, grade, multifocality, receptor status, number of abnormal imaged nodes and presence of lympho-vascular invasion (LVI) were recorded. Data were analysed using chi-squared and Student's t-test.

RESULTS

One hundred and sixty-six patients underwent ALND for pT1-2 breast cancer. Seventy patients had no clinically palpable lymphadenopathy but a positive USS-guided biopsy. Of 70 patients, 32 women (46%) had low disease burden, whereas 38 women (54%) had higher axillary disease in final histology. LVI and >1 abnormal lymph node on USS were both significantly associated with higher disease burden (p = 0.050 and 0.009, respectively).

CONCLUSION

Our study confirms the presence of an important patient cohort, who are clinically node-negative with a positive USS-guided biopsy and a low volume of axillary disease. No imaging modality currently has the accuracy required to identify patients with this low disease burden preoperatively but we propose a simple algorithm for axillary management in this subgroup.

Advanced breast conservation and partial breast reconstruction - a review of current available options for oncoplastic breast surgery

Breast cancer is the most common cancer affecting one in three women with new cancer diagnosis in England. Breast-conserving surgery is the primary surgical option in a vast majority of these patients. Use of oncoplastic techniques in breast conservation surgery has significantly improved the aesthetic outcomes without compromising the oncological safety of cancer resections. Oncoplastic breast-conserving surgery (OPBCS) has transformed the specialty with a paradigm shift in ideology and the recognition that aesthetic and oncological resections are synonymous when planning surgical intervention for patients with breast cancer. The two main options for OPBCS are therapeutic mammoplasty and partial beast reconstruction using pedicle-based flaps. This review aims to highlight key concepts in OPBCS demonstrating an overview of these surgical techniques, their safety, outcomes and the emergence of extreme oncoplastic breast surgery.

Supracapsular phacoemulsification: Description of the "Garde à vous" technique and comparative clinical results

Phacoemulsification techniques can be divided into 2 categories: endocapsular and supracapsular techniques. Supracapsular techniques involve phacoemulsification of the nucleus outside and above the capsular plane. The "Garde-à-vous" technique described in this manuscript is a modified and improved version of the supracapsular procedure with up-to-date technology in micro-coaxial surgery. It maintains the known advantages of supracapsular techniques such as faster surgical times and lower rates of capsular tears and brings a standardized technique with well-defined surgical steps in order to achieve tilting of the nucleus in a vertical or oblique position in almost 100% of cases by performing a double-wave hydro-dissection. The authors also give the results of a non-randomized prospective study, comparing the "Garde-à-vous" technique and the standard "cracking" technique in 2856 cases. The results show that for the "Garde-à-vous group", the patients were significantly younger (P<0.001), the power of ultrasound used was greater (P<0.001) for lower UST (ultrasound time or average phacoemulsification time APT) and EPT (effective phacoemulsication time) (P<0.001), the duration of the procedure was shorter (P<0.001), patient discomfort was less (P<0.001), and the power of the implants used was lower (P<0.01). With regard to the gender of the patients, the percentage of topical anesthesia and the rate of intraoperative complications (posterior capsular rupture), there was no statistically significant difference.

Influence of defect on the electrical and optical properties of A-site non-stoichiometry Ca0.67La0.22□0.11Ti(1−x)CrxO3−δ perovskite

An investigation of the dielectric dispersion, electrical properties, scaling behavior and optical defects of Ca_0.67La_0.22□_0.11Ti_(1−x)Cr_xO_3−δ (CLT_(1−x)Cr_x) with x = 0 and x = 0.1 compositions is presented. The square in the formula is attributed to a vacancy in A-site. Relaxation phenomena were studied with dielectric and modulus formalism, while, the conductivity mechanism was investigated using electrical conductivity. A high permittivity of around 10⁴, low dielectric loss and low electrical conductivity of around 10⁻³ S cm⁻¹ for Ca_0.67La_0.22TiO₃ (CLT) was observed. These values make this composition interesting for microelectric applications. A comparison between the Z′′ and M′′ indicated that the short-range carrier motion dominates at low temperature and becomes less localized at high temperature. The optical defects of CLT and Ca_0.67La_0.22Ti_0.9Cr_0.1O₃ (CLT_0.9Cr_0.1) were studied by electron paramagnetic resonance (EPR) spectroscopy. The results suggest the formation of a [TiO₆]⁹⁻ center, a (Ti³⁺–V_O) center, and dipole defect for CLT compound and Cr³⁺–V_O center defect for CLT_0.9Cr_0.1 compound. These defects are the source of the in-gap electron traps, which improve the optical properties of CLT_(1−x)Cr_x and hence make it an interesting optical material for different applications.

An investigation of the real part of permittivity for the compositions (a) x = 0 and (b) x = 0.1 solid solution Ca_0.67La_0.22□_0.11Ti_(1−x)Cr_xO_3−δ ceramics.

Lateral tarsal strip versus lateral tarsal strip with three-snip punctoplasty for managing epiphora in involutional ectropion

PURPOSE

To compare the efficacy of two surgical techniques-lateral tarsal strip (canthoplasty) alone, and lateral tarsal strip with three-snip punctoplasty-in reducing epiphora arising from involutional ectropion with partial punctal stenosis.

METHODS

Fourty patients with involutional ectropion and partial stenosis of the lacrimal punctum were randomly allocated to two treatment groups. Group 1 patients received lateral tarsal strip alone with only non-invasive stenting of the punctum, and group 2 patients received tarsal strip plus three-snip punctoplasty. Subjective assessment of epiphora was achieved via completion of a quality of life (QoL) questionnaire preoperatively and at postoperative month 3. Eyelid position, adverse outcomes and corneal dryness (via Oxford grading scheme) were also assessed postoperatively. Only patients with unilateral problems were included in the study.

RESULTS

Forty eyes of 40 patients were included: 20 in each group. The mean ages of group 1 and group 2 patients were 79±11 and 80±9 years, respectively. All patients reported significantly reduced eye watering after surgery, with no significant intergroup difference in subjective outcomes, except that computer usage and night driving (P<0.05), improved in a more significant way in group 2. Eyelid malposition was corrected in all cases, there were no cases of postoperative punctal eversion, and no significant adverse events or complications occurred. Finally, the mean improvements in the dryness/keratitis score (using the Oxford scheme) were comparable between the 2 groups (P=0.34).

CONCLUSION

The study findings indicate that treatment of involutional ectropion with partial punctal stenosis by lateral tarsal strip with three snip punctoplasty does not provide greater reduction in discomfort secondary to epiphora than conventional lateral tarsal strip alone, except for specific situations such as night driving or computer use.

Magnetic, magnetocaloric and critical behavior investigation of La0.7Ca0.1Pb0.2Mn1−x−yAlxSnyO3 (x, y = 0.0, 0.05 and 0.075) prepared by a sol–gel method

A systematic study on the magnetic, magnetocaloric and critical behavior properties of polycrystalline La_0.7Ca_0.1Pb_0.2Mn_1−x−yAl_xSn_yO₃ prepared via a sol–gel method are studied.

Beyond Reproduction: Pituitary Hormone Actions on Bone

The long-held belief that pituitary hormones act solely on master targets was first questioned when we documented G protein-coupled receptors for thyroid-stimulating hormone, follicle-stimulating hormone, adrenocorticotrophic hormone, oxytocin, and vasopressin on bone cells. These evolutionarily conserved hormones and their receptors are known to have primitive roles, and exist in invertebrate species as far down as coelenterates. It is not surprising therefore that each such hormone has multiple hitherto unrecognized functions in mammalian integrative physiology, and hence, becomes a potential target for therapeutic intervention. Here we discuss the skeletal actions of pituitary hormones.

T3 Regulates a Human Macrophage-Derived TSH-β Splice Variant: Implications for Human Bone Biology

TSH and thyroid hormones (T3 and T4) are intimately involved in bone biology. We have previously reported the presence of a murine TSH-β splice variant (TSH-βv) expressed specifically in bone marrow-derived macrophages and that exerted an osteoprotective effect by inducing osteoblastogenesis. To extend this observation and its relevance to human bone biology, we set out to identify and characterize a TSH-β variant in human macrophages. Real-time PCR analyses using human TSH-β-specific primers identified a 364-bp product in macrophages, bone marrow, and peripheral blood mononuclear cells that was sequence verified and was homologous to a human TSH-βv previously reported. We then examined TSH-βv regulation using the THP-1 human monocyte cell line matured into macrophages. After 4 days, 46.1% of the THP-1 cells expressed the macrophage markers CD-14 and macrophage colony-stimulating factor and exhibited typical morphological characteristics of macrophages. Real-time PCR analyses of these cells treated in a dose-dependent manner with T3 showed a 14-fold induction of human TSH-βv mRNA and variant protein. Furthermore, these human TSH-βv-positive cells, induced by T3 exposure, had categorized into both M1 and M2 macrophage phenotypes as evidenced by the expression of macrophage colony-stimulating factor for M1 and CCL-22 for M2. These data indicate that in hyperthyroidism, bone marrow resident macrophages have the potential to exert enhanced osteoprotective effects by oversecreting human TSH-βv, which may exert its local osteoprotective role via osteoblast and osteoclast TSH receptors.

The oxytocin-bone axis

We recently demonstrated a direct action of oxytocin (OT) on skeletal homeostasis, mainly mediated through stimulation of osteoblasts (OBs) formation and through the reciprocal modulation of osteoclast (OCs) formation and function. Thus, mice lacking the hormone or its receptor develop a low turnover osteoporosis that worsens with age in both sexes. The skeletons of OT (Ot) and OT receptor (Oxtr) null mice display a pronounced decrease in vertebral and femoral trabecular volume. At the cellular level, OBs from Ot KO and Oxtr KO mice exhibit lower mineralization activity and, at the mRNA level, all master genes for osteoblast differentiation are down-regulated. Moreover, OT has dual effects on OCs: it increases osteoclast formation both directly, by activating nuclear factor kB (NFkB) and mitogen-activated protein kinase (MAPK) signalling and, indirectly, through the up-regulation of receptor activator nuclear factor-kappaB ligand synthesis by OBs. On the other hand, it inhibits bone resorption by triggering cytosolic Ca(2+) release and nitric oxide synthesis in mature OCs. OT is locally produced by osteoblasts acting as paracrine-autocrine regulators of bone formation modulated by oestrogens. The oestrogen signal involved in this feedforward circuit is nongenomic because it requires an intact MAPK kinase signal transduction pathway, instead of the classical nuclear translocation of oestrogen receptor. The ability of oestrogen to increase bone mass in vivo is to some extent OXTR-dependent. Thus, Oxtr KO mice injected 17β-oestradiol did not show any effects on bone formation parameters, whereas the same treatment increases trabecular and cortical bone in wild-type mice. An intact OT autocrine-paracrine circuit appears to be essential for optimal skeletal remodelling.

Thyroid and bone: macrophage-derived TSH-β splice variant increases murine osteoblastogenesis

It is now firmly established that TSH may influence the physiology and patho-physiology of bone by activating osteoblasts and inhibiting osteoclast activity resulting in relative osteoprotection. Whether this influence is directly exerted by pituitary-derived TSH in vivo is less certain, because we have previously reported that the suppression of pituitary TSH does not remove such protection. Here, we have characterized the functional relevance of a novel form of the TSH-β subunit, designated TSH-βv, known to be produced by murine bone marrow cells. We found that fresh bone marrow-derived macrophages (MØs) preferentially produced TSH-βv and, when cocultured with CHO cells engineered to overexpress the full-length TSH receptor, were able to generate the production of intracellular cAMP; a phenomenon not seen in control CHO cells, such results confirmed the bioactivity of the TSH variant. Furthermore, cocultures of MØs and osteoblasts were shown to enhance osteoblastogenesis, and this phenomenon was markedly reduced by antibody to TSH-β, suggesting direct interaction between MØs and osteoblasts as observed under the electron microscope. These data suggest a new paradigm of local modulation of bone biology by a MØ-derived TSH-like molecule and raise the question of the relative contribution of local vs pituitary-derived TSH in osteoprotection.

Association between helicobacter pylori and open angle glaucoma: current perspective

Helicobacter pylori is a Gram negative, spiral-shaped, strictly micro-aerophilic and flagellate human pathogen that can inhabit many areas of stomach. H. pylori infection leads to the generation of oxygen free radicals. H. pylori infection might also aggravate the course of glaucoma by increasing the levels of nitric oxide, endothelin-1 and free radicals indirectly. This article briefly reviews the current perspectives on this issue.

Transformation of coffee (Coffea Arabica L. cv. Catimor) with the cry1ac gene by biolistic, without the use of markers

The transformation of coffee plantlets with the cry1ac gene of Bacillus thuringiensis was achieved by biolistic using either the whole pUBC plasmid or only the ubi-cry1ac-nos genetic cassette. The cry1ac gene was inserted into coffee plants in order to confer resistance to the leaf miner Leucoptera coffeella, an insect responsible for considerable losses in coffee crops. Bearing in mind that the genetic cassettes used for this study lack reporter genes and/or selection marker genes, the parameters for the transformation procedure by biolistic were previously standardised with a plasmid carrying the gus reporter gene. The presence of the cry1ac gene in young plantlet tissues was determined by PCR, Southern blot and reverse transcription-PCR. Our results show that the obtainment of viable coffee plantlets, transformed by bombardment with the cry1ac gene and without selection markers nor reporter genes, is feasible.

Calcium signalling and calcium transport in bone disease

Calcium transport and calcium signalling mechanisms in bone cells have, in many cases, been discovered by study of diseases with disordered bone metabolism. Calcium matrix deposition is driven primarily by phosphate production, and disorders in bone deposition include abnormalities in membrane phosphate transport such as in chondrocalcinosis, and defects in phosphate-producing enzymes such as in hypophosphatasia. Matrix removal is driven by acidification, which dissolves the mineral. Disorders in calcium removal from bone matrix by osteoclasts cause osteopetrosis. On the other hand, although bone is central to management of extracellular calcium, bone is not a major calcium sensing organ, although calcium sensing proteins are expressed in both osteoblasts and osteoclasts. Intracellular calcium signals are involved in secondary control including cellular motility and survival, but the relationship of these findings to specific diseases is not clear. Intracellular calcium signals may regulate the balance of cell survival versus proliferation or anabolic functional response as part of signalling cascades that integrate the response to primary signals via cell stretch, estrogen, tyrosine kinase, and tumor necrosis factor receptors.

Molecular physiology and pharmacology of calcitonin

Calcitonin is a thirty-two amino acid peptide that contains an N-terminal disulphide bridge and a C-terminal prolineamide residue. It is released from thyroid parafollicular C-cells and its direct actions on the osteoclast account for its physiological effects whether as a hypocalcaemic agent and a potent inhibitor of bone resorption. These effects likely reflect actions upon a number of specific osteoclast cell surface receptors that initiate intracellular signaling events through both cyclic AMP and calcium mediated second messenger pathways. Studies of its potent anti-resorptive effects have significant translational implications in the management of Paget's bone disease, osteoporosis, and hypercalcaemia. This chapter summarizes major concepts in the synthesis and structure of calcitonin and then proceeds to outline its cellular, molecular actions and therapeutic applications, whilst seeking to provide a reference source. More detailed accounts have been given on different aspects of calcitonin physiology and biochemistry in a number of recent reviews by ourselves and others (155,157, Zaidi et al., 1994; 2002).

A profile and spectrum of four cases of methicillin-resistant Staphylococcus aureus in a burns intensive care unit

This report describes and evaluates four patients with hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas infections at the Burns and Plastic Surgery Hospital, in Libya, between August 1999 and August 2002. Neither rifampicin nor vancomycin was used to treat these patients. Inhalation injury with major burns (> 60% total body surface area), a major degree of burns (3rd degree), and septicaemia caused by both MRSA and multi-resistant P. aeruginosa invariably proved fatal. One patient responded well to antibiotic therapy, but the other three died in spite of similar therapy. Vancomycin and rifampicin should be established as the first choice to treat MRSA infection, and infected wounds need aggressive management with antibiotics prior to skin grafting.

Biological properties and mechanism of action of ibandronate: application to the treatment of osteoporosis

Bisphosphonates, with their proven efficacy and safety, are the most commonly prescribed treatment for women with postmenopausal osteoporosis; however, optimal efficacy is often not achieved due to poor patient adherence to medication. Poor adherence leads to an increased risk of fracture, which itself results in morbidity, elevated healthcare costs and potentially, mortality. Although weekly rather than daily dosing of bisphosphonates has improved adherence, there remains a significant problem, and dosing less frequently than weekly has been suggested as a possible means for further improving adherence. Ibandronate is a new bisphosphonate that has a specific structure and set of characteristics that enable less frequent dosing than currently available bisphosphonates. This review provides details of the general structural features of all bisphosphonates and how these are understood to contribute to their functions in osteoporosis treatment. From this, the unique structure of ibandronate is described, along with how this translates into the high antiresorptive potency, favorable bone-binding, persistence in bone, and good tolerability that permits less frequent dosing. Finally, the clinical evidence for ibandronate is briefly presented, demonstrating the viability of less frequent dosing, with its potential benefits for patient convenience and adherence to therapy.

Calcium absorption and bone mineral density in celiacs after long term treatment with gluten-free diet and adequate calcium intake

Calcium malabsorption, hypocalcemia and skeletal demineralization are well-recognized features of untreated celiac disease. This study investigates calcium absorption and bone mineral density (BMD) after a prolonged, over 4 years, treatment with a gluten-free diet. Twenty-four adult females with treated celiac disease and twenty age- and sex-matched control subjects were studied. Mean body mass index (MBI), energy intake, serum calcium, and serum 25(OH)D concentrations in treated celiacs did not differ from controls. However, while both dietary calcium and protein intake were significantly higher in celiacs (P<0.012), fractional calcium absorption was lower (mean percentage+/-SD; treated 39.8+/-12 versus controls 52.3+/-10, P<0.001). Thus, after adjusting for calcium intake, the estimated amount of calcium absorbed daily was similar in both groups. Whole body, spine and trochanter BMD were significantly lower in treated celiac patients compared with controls (P<0.05). There were significant inverse correlations between: serum parathyroid hormone (PTH) and femoral neck or total body BMD (P<0.01), PTH and duration of gluten-free diet (P=0.05), and fractional calcium absorption and alkaline phosphatase (P=0.022). Increased calcium intake could potentially compensate for the reduced fractional calcium absorption in treated adult celiac patients, but may not normalize the BMD. In addition, the inverse correlation between PTH and time following treatment is suggestive of a continuing long-term benefit of gluten withdrawal on bone metabolism in celiac patients.

Efferent loop small intestinal vitamin D receptor concentration and bone mineral density after Billroth II (Polya) gastrectomy in humans

Animal studies have demonstrated that the highest concentration of vitamin D receptors (and greatest capacity for active calcium absorption) occurs in the proximal duodenum. By passing the duodenum following Polya/Billroth II gastrectomy could result in the development of a metabolic bone disease and low bone mineral density (BMD). We thus compared the vitamin D receptor (VDR) concentration in mucosal biopsies taken at endoscopy from two functionally corresponding areas of the small intestine: the jejunum (or efferent loop) in 21 patients with a history of Polya/Billroth II gastrectomy and the second part of the duodenum in age/sex-matched control subjects. We also measured the BMD by dual energy X-ray absorptiometry. The mean VDR concentration was not significantly different between the two groups (patients vs controls, fmol/mg protein, mean +/- SE: 34.99 +/- 2.57 vs 34.67 +/- 3.71; P = 0.22), even when subgrouped as males (36.22 +/- 3.16 vs 31.2 +/- 4.24; P = 0.351) or females (31.93 +/- 4.7 vs 43 +/- 6.76; P = 0.193). In Polya/Billroth II gastrectomy patients, the VDR concentration in the efferent loop declined with age (r = -0.78, P = 0.02). In the same group, BMD, as compared with matched controls, was significantly reduced at the lumbar spine (Z-score: patients vs controls: -1.138 vs 0.099, P = 0.01), but not at the femoral neck (Z-score: -0.69 vs 0.7, P = 0.084). There was no correlation between VDR and time since operation or BMD. These results suggest that following Polya/Billroth II gastrectomy, the functional capacity of the jejunal efferent loop in reference to VDR concentration is similar to that of the second part of the duodenum in normal subjects. Therefore, the reduced BMD in our patients, also a common finding in other studies, may not be secondary to the reduced capacity of the VDR system that facilitates the active calcium transport pathway in the proximal small intestine.

Ursodeoxycholic acid enhances fractional calcium absorption in primary biliary cirrhosis

Bone disease is a frequently reported complication in primary biliary cirrhosis (PBC), but its pathogenesis is poorly understood. Calcium malabsorption has been considered as an important contributing factor. Ursodeoxycholic acid (UDCA) is the treatment of choice in PBC, improving survival, but its effect on calcium absorption is unknown. In this study, we have measured fractional calcium absorption, using a single isotope method, in a group of female PBC patients (median age: 60 years, range: 46-78 years) and age-matched female controls (median age: 58 years, range: 36-74). Bone mineral density (BMD) in PBC patients was significantly lower than age-matched controls (g/cm(2) +/- SEM; lumbar spine: controls 1.139+/-0.028, PBC patients 1.004+/-0.026, p = 0.0028; femoral neck: controls 0.944+/-0.034, PBC patients 0.819+/-0.023, p = 0.0032). Twenty two PBC patients, who were not vitamin D-deficient, were off and on UDCA for approximately 1 month and approximately 8 weeks, respectively. Fractional calcium absorption in PBC patients prior to UDCA treatment (mean +/- SEM, 33.8+/-2.6%) was significantly lower than controls (52.0+/-2.4%, p<0.001). Following UDCA therapy, fractional calcium absorption increased significantly (Off UDCA: 33.1+/-2.6%, On UDCA: 36.6+/-2.5%, p<0.0058). Osteocalcin levels were significantly raised in the PBC group (mean +/- SEM, ng/ml, 41.4+/-2.02) compared to controls (31.1+/-2.64, p = 0.002). There were no differences in parathyroid hormone (PTH) or 25-hydroxyvitamin D levels between these two groups or following UDCA therapy. In conclusion, we found that PBC patients display low spinal and femoral neck BMD, reduced fractional calcium absorption, and elevated plasma osteocalcin. The calcium malabsorption is corrected partially by UDCA therapy. Long-term studies are required to determine whether this effect can be sustained, and whether a sustained increase in fractional calcium absorption can translate into a favorable change in bone strength in patients with PBC.

Differential effects of interleukin-6 receptor activation on intracellular signaling and bone resorption by isolated rat osteoclasts

The effects of the related cytokines interleukin-6 (IL-6), leukemia inhibitory factor (LIF) and oncostatin-M on bone resorption and cytosolic Ca(2+) signaling were compared in isolated rat osteoclasts. In the traditional disaggregated osteoclast (pit) assay, IL-6 and LIF, but not oncostatin-M, conserved the bone resorption otherwise inhibited by high extracellular [Ca(2+)] (15 mM). It produced a paradoxical, concentration-dependent stimulation of resorption by elevated extracellular Ca(2+). In the micro-isolated single osteoclast resorption assay, IL-6, high [Ca(2+)] or IL-6 plus high [Ca(2+)] all increased pit formation. In contrast, the IL-6 receptor (IL-6R)-specific agonist antibody MT-18 inhibited bone resorption in a concentration-dependent manner (1:500 to 1:500 000). MT-18 triggered cytosolic Ca(2+) signals in fura 2-loaded osteoclasts within approximately 10 min of application. Each cytosolic Ca(2+) transient began with a peak deflection that persisted in Ca(2+)-free, EGTA-containing extracellular medium, consistent with a release of intracellularly stored Ca(2+). This was followed by a sustained elevation of cytosolic [Ca(2+)] that was abolished in Ca(2+)-free medium, as expected from an entry of extracellular Ca(2+), and by the Ca(2+) channel antagonist Ni(2+). The inclusion of either IL-6 or soluble human (sh) IL-6R specifically reversed both the above effects of MT-18, confirming that both effects were specific for the IL-6R. The findings suggest that IL-6R activation by IL-6 stimulates osteoclastic bone resorption either by reversing the inhibitory effect of high extracellular Ca(2+) in stromal-containing systems or itself stimulating bone resorption along with Ca(2+) by micro-isolated osteoclasts. In contrast, activation of the IL-6R by an agonist antibody produces an inhibition of bone resorption and an associated triggering of the cytosolic Ca(2+) signals previously associated with regulation of bone resorptive function in other situations.

New insights into the regulation of cathepsin K gene expression by osteoprotegerin ligand

Cathepsin K plays a key role in bone resorption. We provide the first evidence that osteoprotegerin ligand (OPGL), a critical pro-resorptive cytokine, acutely stimulates the expression of cathepsin K in osteoclasts. We used in situ RT-PCR and real time quantitative RT-PCR to analyze cathepsin K gene expression. OPGL enhanced cathepsin K mRNA levels in mature osteoclasts isolated from rat neonatal long bones. OPGL together with macrophage colony-stimulating factor (M-CSF) also stimulated cathepsin K gene expression in monocytic cells and multinucleate osteoclasts in bone marrow cultures. Real time quantitative RT-PCR demonstrated high levels of cathepsin K mRNA in bone marrow cultures, paralleling the degree of osteoclastogenesis. We therefore suggest that OPGL enhances bone resorption, at least in part, by inducing cathepsin K gene expression.

Macrophage colony-stimulating factor suppresses osteoblast formation

We provide the first evidence that the bone marrow-derived cytokine, macrophage colony-stimulating factor (M-CSF), inhibits the formation of bone-forming osteoblasts. We examined both osteoclast and osteoblast formation in primary rat bone marrow cultures. As expected, M-CSF together with osteoprotegerin ligand (OPGL) markedly accelerated osteoclastogenesis. In contrast, treatment with M-CSF alone yielded no osteoclasts at any time. The most striking and novel observation was that M-CSF with or without OPGL dramatically suppressed osteoblast formation. In separate experiments, estradiol markedly suppressed osteoclast formation in the M-CSF/OPGL-treated cultures independently of osteoblasts. Consistent with this was the expression of estrogen receptor-alpha (ERalpha) and ERbeta mRNA in osteoclast precursors. We therefore conclude that in addition to the well-known action of M-CSF to modulate osteoclastogenesis, this cytokine may also regulate osteoblast formation.

A two year global evaluation of the susceptibility of Candida species to fluconazole by disk diffusion

The in-vitro activity of fluconazole against 46,831 yeast isolates collected over a two-year period from 57 laboratories in 33 countries worldwide was assessed using a disc diffusion method. Candida albicans was the organism isolated most frequently, accounting for 68.6% of the total number of isolates. C. glabrata, C. tropicalis, C parapsilosis and C. krusei and Cryptococcus neoformans represented 9.9, 4.7, 4.3, 1.9, and 1.4% of isolates respectively during the 2 year period and rates varied markedly between countries. In 1999 data blood isolates represented 4.9% of all isolates and intensive care unit isolates represented 9.9%. In both the 1998 and 1999 data, 99% of C. albicans were fully susceptible (S) to fluconazole, and 95.6% of all species of yeasts tested were S or susceptible-dose dependent (S-DD) to fluconazole. No emerging trends of resistance were noted with any of the Candida spp. tested as 96% of all isolates retained susceptibility (S or S-DD) to this agent.

Identification and Characterization of a Sodium/Calcium Exchanger, NCX-1, in Osteoclasts and Its Role in Bone Resorption

We provide the first demonstration for a Na+/Ca2+ exchanger, NCX-1, in the osteoclast. We speculate that by using Na+ exchange, NCX-1 couples H+ extrusion with Ca2+ fluxes during bone resorption. Microspectrofluorimetry of fura-2-loaded osteoclasts revealed a rapid and sustained, but reversible, cytosolic Ca2+ elevation upon Na+ withdrawal. This elevation was abolished by the cytosolic introduction (by gentle permeabilization) of a highly specific Na+/Ca2+ exchange inhibitor peptide, XIP, but not its inactive analogue, sXIP. Confocal microscopy revealed intense plasma membrane immunofluorescence with an isoform-specific monoclonal anti-NCX-1 antibody applied to gently permeabilized osteoclasts. Electrophysiological studies using excised outside-in membrane patches showed a low-conductance, Na+-selective, dichlorobenzamil-sensitive, amiloride-insensitive channel that we tentatively assigned as being an NCX. Finally, to examine for physiological relevance, an osteoclast resorption (pit) assay was performed. There was a dramatic reduction of bone resorption following NCX-1 inhibition by dichlorobenzamil and XIP (but not with S-XIP). Together, the results suggest that a functional NCX, likely NCX-1, is involved in the regulation of osteoclast cytosolic Ca2+ and bone resorption.

Molecular cloning, expression, and functional characterization of a novel member of the CD38 family of ADP-ribosyl cyclases

We report the molecular cloning and functional characterization of a novel member of the CD38 family of cyclic ADP-ribose (cADPr)-generating cyclases. We cloned a cDNA insert that encoded a 298-amino-acid-long protein (M(w) approximately 39 kDa). The predicted protein displayed 69, 61, and 58% similarity, respectively, to mouse, rat, and human CD38. Rabbit CD38 was also 28% homologous to Aplysia ADP-ribosyl cyclase and leukocyte CD157 (another ADP-ribosyl cyclase); the three cyclases shared 10 cysteine and 2 adjacent proline residues. We then transfected CD38-negative NIH3T3 cells with cDNA encoding a CD38-EGFP fusion protein. Epifluorescence microscopy showed intense EGFP fluorescence confirming CD38 expression. We finally confirmed the ADP-ribosyl cyclase activity of the expressed CD38 by measuring its ability to catalyze the cyclization of the nicotinamide adenine dinucleotide (NAD(+)) surrogate, NGD(+), to its fluorescent nonhydrolyzable derivative, cGDPr.

Novel biochemical and functional insights into nuclear Ca(2+) transport through IP(3)Rs and RyRs in osteoblasts

We report the first biochemical and functional characterization of inositol trisphosphate receptors (IP(3)Rs) and ryanodine receptors (RyRs) in the nuclear membrane of bone-forming (MC3T3-E1) osteoblasts. Intact nuclei fluoresced intensely with anti-RyR (Ab(34)) and anti-IP(3)R (Ab(40)) antisera in a typically peripheral nuclear membrane pattern. Isolated nuclear membranes were next subjected to SDS-PAGE and blotted with isoform-specific anti-receptor antisera, notably Ab(40), anti-RyR-1, anti-RyR-2 (Ab(129)), and anti-RyR-3 (Ab(180)). Only anti-RyR-1 and Ab(40) showed bands corresponding, respectively, to full-length RyR-1 ( approximately 500 kDa) and IP(3)R-1 (approximately 250 kDa). Band intensity was reduced by just approximately 20% after brief tryptic proteolysis of intact nuclei; this confirmed that isolated nuclear membranes were mostly free of endoplasmic reticular contaminants. Finally, the nucleoplasmic Ca(2+) concentration ([Ca(2+)](np)) was measured in single nuclei by using fura-dextran. The nuclear envelope was initially loaded with Ca(2+) via Ca(2+)-ATPase activation (1 mM ATP and approximately 100 nM Ca(2+)). Adequate Ca(2+) loading was next confirmed by imaging the nuclear envelope (and nucleoplasm). Exposure of Ca(2+)-loaded nuclei to IP(3) or cADP ribose resulted in a rapid and sustained [Ca(2+)](np) elevation. Taken together, the results provide complementary evidence for nucleoplasmic Ca(2+) influx in osteoblasts through nuclear membrane-resident IP(3)Rs and RyRs. Our findings may conceivably explain the direct regulation of osteoblastic gene expression by hormones that use the IP(3)-Ca(2+) pathway.

IP(3), IP(3) receptor, and cellular senescence

Herein we demonstrate that replicative cellular senescence in vitro results in sharply reduced inositol 1,4,5-trisphosphate (IP(3)) receptor levels, reduced mitogen-evoked IP(3) formation and Ca(2+) release, and Ca(2+) store depletion. Human diploid fibroblasts (HDFs) underwent either 30 mean population doublings [mean population doublings (MPDs) thymidine labeling index (TI) >92% ("young") or between 53 and 58 MPDs (TI < 28%; "senescent")]. We found that the cytosolic Ca(2+) release triggered by either ionomycin or by several IP(3)-generating mitogens, namely bradykinin, thrombin, platelet-derived growth factor (PDGF), and epidermal growth factor (EGF), was attenuated markedly in senescent HDFs. Notably, the triggered cytosolic Ca(2+) transients were of a smaller magnitude in senescent HDFs. However, the response latency seen with both PDGF and EGF was greater for senescent cells. Finally, a smaller proportion of senescent HDFs showed oscillations. In parallel, IP(3) formation in response to bradykinin or EGF was also attenuated in senescent HDFs. Furthermore, senescent HDFs displayed a sharply diminished Ca(2+) release response to intracellularly applied IP(3). Finally, to compare IP(3) receptor protein levels directly in young and senescent HDFs, their microsomal membranes were probed in Western blots with a highly specific anti-IP(3) receptor antiserum, Ab(40). A approximately 260-kDa band corresponding to the IP(3) receptor protein was noted; its intensity was reduced by approximately 50% in senescent cells. Thus, we suggest that reduced IP(3) receptor expression, lowered IP(3) formation, and Ca(2+) release, as well as Ca(2+) store depletion, all contribute to the deficient Ca(2+) signaling seen in HDFs undergoing replicative senescence.

[Epidemic of pneumonia associated with mechanical ventilation in Mérida, Yucatán]

OBJECTIVE

To determine the main epidemiological, clinical, and microbiologic characteristics of an outbreak of ventilator-associated pneumonia at an intensive care unit in Yucatan.

MATERIAL AND METHODS

An 11-month prospective and observational study was designed to determine incidence, mortality, potential reservoirs, etiologic agents and antibiotic susceptibility patterns.

RESULTS

The incidence of ventilator-associated pneumonia was 74%. The crude mortality rate was 88% compared to a 19.5% expected-mortality rate. Gram-negative bacteria were isolated from 98% of the cultures, of which 46% were susceptible to third generation cephalosporins, 59% to fourth generation cephalosporins, 70% to ciprofloxacin and 100% to imipenem. Klebsiella pneumoniae and Pseudomonas aeruginosa were isolated from some of the ventilator circuits and the sink.

CONCLUSIONS

The high incidence of pneumonia and associated mortality in our intensive care unit may be attributed to the absence of infection control measures and the high prevalence of multiresistant organisms which is related to antibiotic abuse.

A new function for CD38/ADP-ribosyl cyclase in nuclear Ca2+ homeostasis

Nucleoplasmic calcium ions (Ca2+) influence nuclear functions as critical as gene transcription, apoptosis, DNA repair, topoisomerase activation and polymerase unfolding. Although both inositol trisphosphate receptors and ryanodine receptors, types of Ca2+ channel, are present in the nuclear membrane, their role in the homeostasis of nuclear Ca2+ remains unclear. Here we report the existence in the inner nuclear membrane of a functionally active CD38/ADP-ribosyl cyclase that has its catalytic site within the nucleoplasm. We propose that the enzyme catalyses the intranuclear cyclization of nicotinamide adenine dinucleotide to cyclic adenosine diphosphate ribose. The latter activates ryanodine receptors of the inner nuclear membrane to trigger nucleoplasmic Ca2+ release.