Systemic Anti-Inflammatory Agents in the Prevention of Chemoradiation-Induced Mucositis: A Review of Randomised Controlled Trials.

Mucositis is a pathological condition characterised by inflammation and ulceration of the mucous membranes lining the alimentary canal, particularly in the mouth (oral mucositis) and the gastrointestinal tract. It is a common side effect of cancer treatments, including chemotherapy and radiotherapy, and it is sometimes responsible for treatment interruptions. Preventing mucositis throughout the alimentary tract is therefore crucial. However, current interventions mainly target either oral or gastrointestinal side effects. This review aimed to investigate the use of systemically administered anti-inflammatory agents to prevent mucositis in cancer patients undergoing cancer treatment. PubMed, Ovid, Scopus, Web of Science, WHO ICTRP and ClinicalTrials.gov were screened to identify eligible randomised controlled trials (RCTs). The published literature on anti-inflammatory agents provides mixed evidence regarding the degree of efficacy in preventing/reducing the severity of mucositis in most anticancer treatments; however, sample size continued to be a significant limitation, alongside others discussed. Our review yielded a list of several anti-inflammatory agents that exhibit potential mucositis-preventive effects in cancer patients undergoing cancer treatment, which can be used to inform clinical practice.

Identification of 2-Aryl-Quinolone Inhibitors of Cytochrome bd and Chemical Validation of Combination Strategies for Respiratory Inhibitors against Mycobacterium tuberculosis.

Mycobacterium tuberculosis cytochrome bd quinol oxidase (cyt bd), the alternative terminal oxidase of the respiratory chain, has been identified as playing a key role during chronic infection and presents a putative target for the development of novel antitubercular agents. Here, we report confirmation of successful heterologous expression of M. tuberculosis cytochrome bd. The heterologous M. tuberculosis cytochrome bd expression system was used to identify a chemical series of inhibitors based on the 2-aryl-quinolone pharmacophore. Cytochrome bd inhibitors displayed modest efficacy in M. tuberculosis growth suppression assays together with a bacteriostatic phenotype in time-kill curve assays. Significantly, however, inhibitor combinations containing our front-runner cyt bd inhibitor CK-2-63 with either cyt bcc-aa3 inhibitors (e.g., Q203) and/or adenosine triphosphate (ATP) synthase inhibitors (e.g., bedaquiline) displayed enhanced efficacy with respect to the reduction of mycobacterium oxygen consumption, growth suppression, and in vitro sterilization kinetics. In vivo combinations of Q203 and CK-2-63 resulted in a modest lowering of lung burden compared to treatment with Q203 alone. The reduced efficacy in the in vivo experiments compared to in vitro experiments was shown to be a result of high plasma protein binding and a low unbound drug exposure at the target site. While further development is required to improve the tractability of cyt bd inhibitors for clinical evaluation, these data support the approach of using small-molecule inhibitors to target multiple components of the branched respiratory chain of M. tuberculosis as a combination strategy to improve therapeutic and pharmacokinetic/pharmacodynamic (PK/PD) indices related to efficacy.

Systematic analysis of Kaposi's sarcoma (KS)-associated herpesvirus genomes from a KS case-control study in Cameroon: Evidence of dual infections but no association between viral sequence variation and KS risk.

In sub-Saharan Africa, Kaposi's sarcoma-associated herpesvirus (KSHV) is endemic, and Kaposi's sarcoma (KS) is a significant public health problem. Until recently, KSHV genotype analysis was performed using variable gene regions, representing a small fraction of the genome, and thus the contribution of sequence variation to viral transmission or pathogenesis are understudied. We performed near full-length KSHV genome sequence analysis on samples from 43 individuals selected from a large Cameroonian KS case-control study. KSHV genomes were obtained from 21 KS patients and 22 control participants. Phylogenetic analysis of the K1 region indicated the majority of sequences were A5 or B1 subtypes and all three K15 alleles were represented. Unique polymorphisms in the KSHV genome were observed including large gene deletions. We found evidence of multiple distinct KSHV genotypes in three individuals. Additionally, our analyses indicate that recombination is prevalent suggesting that multiple KSHV infections may not be uncommon overall. Most importantly, a detailed analysis of KSHV genomes from KS patients and control participants did not find a correlation between viral sequence variations and disease. Our study is the first to systematically compare near full-length KSHV genome sequences between KS cases and controls in the same endemic region to identify possible sequence variations associated with disease risk.

Dual infection and recombination of Kaposi sarcoma herpesvirus revealed by whole-genome sequence analysis of effusion samples.

Kaposi sarcoma herpesvirus (KSHV) is the etiological agent of three malignancies, Kaposi sarcoma (KS), primary effusion lymphoma (PEL) and KSHV-associated multicentric Castelman disease. KSHV infected patients may also have an interleukin six-related KSHV-associated inflammatory cytokine syndrome. KSHV-associated diseases occur in only a minority of chronically KSHV-infected individuals and often in the setting of immunosuppression. Mechanisms by which KSHV genomic variations and systemic co-infections may affect the pathogenic pathways potentially leading to these diseases have not been well characterized in vivo. To date, the majority of comparative genetic analyses of KSHV have been focused on a few regions scattered across the viral genome. We used next-generation sequencing techniques to investigate the taxonomic groupings of viruses from malignant effusion samples from fourteen participants with advanced KSHV-related malignancies, including twelve with PEL and two with KS and elevated KSHV viral load in effusions. The genomic diversity and evolutionary characteristics of nine isolated, near full-length KSHV genomes revealed extensive evidence of mosaic patterns across all these genomes. Further, our comprehensive NGS analysis allowed the identification of two distinct KSHV genome sequences in one individual, consistent with a dual infection. Overall, our results provide significant evidence for the contribution of KSHV phylogenomics to the origin of KSHV subtypes. This report points to a wider scope of studies to establish genome-wide patterns of sequence diversity and define the possible pathogenic role of sequence variations in KSHV-infected individuals.

Regulation of photosynthetic cyclic electron flow pathways by adenylate status in higher plant chloroplasts.

Cylic electron flow (CEF) around Photosystem I in photosynthetic eukaryotes is likely to be necessary to augment ATP production, rapidly- and precisely balancing the plastid ATP/NADPH energy budget to meet the demands of downstream metabolism. Many regulatory aspects of this process are unclear. Here we demonstrate that the higher plant plastid NADH/Fd:plastoquinone reductase (NDH) and proposed PGR5/PGRL1 ferredoxin:plastoquinone reductase (FQR) pathways of CEF are strongly, rapidly and reversibly inhibited in vitro by ATP with Ki values of 670 µM and 240 µM respectively, within the range of physiological changes in ATP concentrations. Control experiments ruled out effects on secondary reactions, e.g. FNR- and cytochrome b6f activity, nonphotochemical quenching of chlorophyll fluorescence etc., supporting the view that ATP is an inhibitor of CEF and its associated pmf generation and subsequent ATP production. The effects are specific to ATP, with the ATP analog AMP-PNP showing little inhibitory effect, and ADP inhibiting only at higher concentrations. For the FQR pathway, inhibition was found to be classically competitive with Fd, and the NDH pathway showing partial competition with Fd. We propose a straightforward model for regulation of CEF in plants in which CEF is activated under conditions when stromal ATP low, but is downregulated as ATP levels build up, allowing for effective ATP homeostasis. The differences in Ki values suggest a two-tiered regulatory system, where the highly efficient proton pumping NDH is activated with moderate decreases in ATP, with the less energetically-efficient FQR pathway being activated under more severe ATP depletion.

The higher plant plastid NAD(P)H dehydrogenase-like complex (NDH) is a high efficiency proton pump that increases ATP production by cyclic electron flow.

Cyclic electron flow around photosystem I (CEF) is critical for balancing the photosynthetic energy budget of the chloroplast by generating ATP without net production of NADPH. We demonstrate that the chloroplast NADPH dehydrogenase complex, a homolog to respiratory Complex I, pumps approximately two protons from the chloroplast stroma to the lumen per electron transferred from ferredoxin to plastoquinone, effectively increasing the efficiency of ATP production via CEF by 2-fold compared with CEF pathways involving non-proton-pumping plastoquinone reductases. By virtue of this proton-pumping stoichiometry, we hypothesize that NADPH dehydrogenase not only efficiently contributes to ATP production but operates near thermodynamic reversibility, with potentially important consequences for remediating mismatches in the thylakoid energy budget.

Rational Design, Synthesis, and Biological Evaluation of Heterocyclic Quinolones Targeting the Respiratory Chain of Mycobacterium tuberculosis.

A high-throughput screen (HTS) was undertaken against the respiratory chain dehydrogenase component, NADH:menaquinone oxidoreductase (Ndh) of Mycobacterium tuberculosis (Mtb). The 11000 compounds were selected for the HTS based on the known phenothiazine Ndh inhibitors, trifluoperazine and thioridazine. Combined HTS (11000 compounds) and in-house screening of a limited number of quinolones (50 compounds) identified ∼100 hits and four distinct chemotypes, the most promising of which contained the quinolone core. Subsequent Mtb screening of the complete in-house quinolone library (350 compounds) identified a further ∼90 hits across three quinolone subtemplates. Quinolones containing the amine-based side chain were selected as the pharmacophore for further modification, resulting in metabolically stable quinolones effective against multi drug resistant (MDR) Mtb. The lead compound, 42a (MTC420), displays acceptable antituberculosis activity (Mtb IC50 = 525 nM, Mtb Wayne IC50 = 76 nM, and MDR Mtb patient isolates IC50 = 140 nM) and favorable pharmacokinetic and toxicological profiles.

Bioaccumulation of methylmercury in a marine diatom and the influence of dissolved organic matter.

The largest bioconcentration step of most metals, including methylmercury (MeHg), in aquatic biota is from water to phytoplankton, but the extent to which dissolved organic matter (DOM) affects this process for MeHg largely remains unexplored in marine systems. This study investigated the influence of specific sulfur-containing organic compounds and naturally occurring DOM on the accumulation of MeHg in a marine diatom Thalassiosira pseudonana. Initial uptake rate constants and volume concentration factors (VCFs) of MeHg were calculated to evaluate MeHg enrichment in algal cells in the presence of a range of organic compound concentrations. At environmentally realistic and higher concentrations, the addition of glycine and methionine had no effect on algal MeHg uptake, but thiol-containing compounds such as cysteine and thioglycolic acid reduced MeHg accumulation in algal cells at high added concentrations (> 100 times higher than naturally occurring concentrations). However, environmentally realistic concentrations of glutathione, another thiol-containing compound as low as 10 nM, resulted in a decline of ~ 30% in VCFs, suggesting its possible importance in natural waters. Humic acid additions of 0.1 and 0.5 mg C/L also reduced MeHg VCFs by ~ 15% and ~ 25%, respectively. The bioaccumulation of MeHg for T. pseudonana in coastal waters with varying levels of dissolved organic carbon (DOC) was inversely correlated with bulk DOC concentrations. Generally, naturally occurring DOM, particularly certain thiol-containing compounds, can reduce MeHg uptake by phytoplankton.

Defects in the Expression of Chloroplast Proteins Leads to H2O2 Accumulation and Activation of Cyclic Electron Flow around Photosystem I.

We describe a new member of the class of mutants in Arabidopsis exhibiting high rates of cyclic electron flow around photosystem I (CEF), a light-driven process that produces ATP but not NADPH. High cyclic electron flow 2 (hcef2) shows strongly increased CEF activity through the NADPH dehydrogenase complex (NDH), accompanied by increases in thylakoid proton motive force (pmf), activation of the photoprotective qE response, and the accumulation of H2O2. Surprisingly, hcef2 was mapped to a non-sense mutation in the TADA1 (tRNA adenosine deaminase arginine) locus, coding for a plastid targeted tRNA editing enzyme required for efficient codon recognition. Comparison of protein content from representative thylakoid complexes, the cytochrome bf complex, and the ATP synthase, suggests that inefficient translation of hcef2 leads to compromised complex assembly or stability leading to alterations in stoichiometries of major thylakoid complexes as well as their constituent subunits. Altered subunit stoichiometries for photosystem I, ratios and properties of cytochrome bf hemes, and the decay kinetics of the flash-induced thylakoid electric field suggest that these defect lead to accumulation of H2O2 in hcef2, which we have previously shown leads to activation of NDH-related CEF. We observed similar increases in CEF, as well as increases in H2O2 accumulation, in other translation defective mutants. This suggests that loss of coordination in plastid protein levels lead to imbalances in photosynthetic energy balance that leads to an increase in CEF. These results taken together with a large body of previous observations, support a general model in which processes that lead to imbalances in chloroplast energetics result in the production of H2O2, which in turn activates CEF. This activation could be from either H2O2 acting as a redox signal, or by a secondary effect from H2O2 inducing a deficit in ATP.

Interplay between the hinge region of iron sulphur protein and the Qo site in the bc1 complex - Analysis of Plasmodium-like mutations in the yeast enzyme.

The respiratory chain bc1 complex is central to mitochondrial bioenergetics and the target of antiprotozoals. We characterized a modified yeast bc1 complex that more closely resemble Plasmodium falciparum enzyme. The mutant version was generated by replacing ten cytochrome b Qo site residues by P. falciparum equivalents. The Plasmodium-like changes caused a major dysfunction of the catalytic mechanism of the bc1 complex resulting in superoxide overproduction and respiratory growth defect. The defect was corrected by substitution of the conserved residue Y279 by a phenylalanine, or by mutations in or in the vicinity of the hinge domain of the iron-sulphur protein. It thus appears that side-reactions can be prevented by the substitution Y279F or the modification of the iron-sulphur protein hinge region. Interestingly, P. falciparum - and all the apicomplexan - contains an unusual hinge region. We replaced the yeast hinge region by the Plasmodium version and combined it with the Plasmodium-like version of the Qo site. This combination restored the respiratory growth competence. It could be suggested that, in the apicomplexan, the hinge region and the cytochrome b Qo site have co-evolved to maintain catalytic efficiency of the bc1 complex Qo site.

Evaluation of radiation doses and associated risk from the Fukushima nuclear accident to marine biota and human consumers of seafood.

Radioactive isotopes originating from the damaged Fukushima nuclear reactor in Japan following the earthquake and tsunami in March 2011 were found in resident marine animals and in migratory Pacific bluefin tuna (PBFT). Publication of this information resulted in a worldwide response that caused public anxiety and concern, although PBFT captured off California in August 2011 contained activity concentrations below those from naturally occurring radionuclides. To link the radioactivity to possible health impairments, we calculated doses, attributable to the Fukushima-derived and the naturally occurring radionuclides, to both the marine biota and human fish consumers. We showed that doses in all cases were dominated by the naturally occurring alpha-emitter (210)Po and that Fukushima-derived doses were three to four orders of magnitude below (210)Po-derived doses. Doses to marine biota were about two orders of magnitude below the lowest benchmark protection level proposed for ecosystems (10 µGy⋅h(-1)). The additional dose from Fukushima radionuclides to humans consuming tainted PBFT in the United States was calculated to be 0.9 and 4.7 µSv for average consumers and subsistence fishermen, respectively. Such doses are comparable to, or less than, the dose all humans routinely obtain from naturally occurring radionuclides in many food items, medical treatments, air travel, or other background sources. Although uncertainties remain regarding the assessment of cancer risk at low doses of ionizing radiation to humans, the dose received from PBFT consumption by subsistence fishermen can be estimated to result in two additional fatal cancer cases per 10,000,000 similarly exposed people.

Antimalarial pharmacology and therapeutics of atovaquone.

Atovaquone is used as a fixed-dose combination with proguanil (Malarone) for treating children and adults with uncomplicated malaria or as chemoprophylaxis for preventing malaria in travellers. Indeed, in the USA, between 2009 and 2011, Malarone prescriptions accounted for 70% of all antimalarial pre-travel prescriptions. In 2013 the patent for Malarone will expire, potentially resulting in a wave of low-cost generics. Furthermore, the malaria scientific community has a number of antimalarial quinolones with a related pharmacophore to atovaquone at various stages of pre-clinical development. With this in mind, it is timely here to review the current knowledge of atovaquone, with the purpose of aiding the decision making of clinicians and drug developers involved in the future use of atovaquone generics or atovaquone derivatives.

Dissolved organic matter reduces algal accumulation of methylmercury.

Dissolved organic matter (DOM) significantly decreased accumulation of methylmercury (MeHg) by the diatom Cyclotella meneghiniana in laboratory experiments. Live diatom cells accumulated two to four times more MeHg than dead cells, indicating that accumulation may be partially an energy-requiring process. Methylmercury enrichment in diatoms relative to ambient water was measured by a volume concentration factor (VCF). Without added DOM, the maximum VCF was 32 × 10(4) , and the average VCF (from 10 to 72 h) over all experiments was 12.6 × 10(4) . At very low (1.5 mg/L) added DOM, VCFs dropped by approximately half. At very high (20 mg/L) added DOM, VCFs dropped 10-fold. Presumably, MeHg was bound to a variety of reduced sulfur sites on the DOM, making it unavailable for uptake. Diatoms accumulated significantly more MeHg when exposed to transphilic DOM extracts than hydrophobic ones. However, algal lysate, a labile type of DOM created by resuspending a marine diatom in freshwater, behaved similarly to a refractory DOM isolate from San Francisco Bay. Addition of 67 µM L-cysteine resulted in the largest drop in VCFs, to 0.28 × 10(4) . Although the DOM composition influenced the availability of MeHg to some extent, total DOM concentration was the most important factor in determining algal bioaccumulation of MeHg.

Relating the sediment phase speciation of arsenic, cadmium, and chromium with their bioavailability for the deposit-feeding polychaete Nereis succinea.

We studied the influence of sediment geochemistry on bioavailability of As, Cd, and Cr in deposit-feeding polychaetes. Metal phase speciation in sediments was determined with a sequential extraction scheme, and assimilation efficiencies (AEs) of ingested metals were determined by pulse-chase feeding experiments using γ-emitting isotopes. Worms were fed sediments collected from geochemically diverse estuaries that were labeled by sorbing dissolved radiotracers or mixing with radiolabeled algae. Uptake of sediment-bound metals was compared with that from labeled algae or goethite. Metal AEs showed a positive relationship with the exchangeable and carbonate sedimentary fractions, whereas metals in iron and manganese oxides and acid-volatile sulfides, or in pyrite and other refractory material, were inversely correlated with AEs. Arsenic was most bioavailable from algae (72%), less from sediments mixed with algae (24-70%) and least from sediments labeled directly (1-12%). Arsenic AEs in sediments labeled directly showed a positive correlation with sedimentary Mn and Al and negative correlation with Fe. Cadmium AEs were positively correlated with salinity and negatively correlated with sedimentary organic C. The AEs of Cr from sediments or algae were less than 5%, but they were 34% from pure goethite. By quantifying the relationship of metal speciation in sediments with their bioavailability for deposit-feeding polychaetes, the present study provides new insight into understanding metal bioaccumulation in benthic invertebrates.

Transforming rhinacanthin analogues from potent anticancer agents into potent antimalarial agents.

Twenty-six novel naphthoquinone aliphatic esters were synthesized by esterification of 1,4-naphthoquinone alcohols with various aliphatic acids. The 1,4-naphthoquinone alcohols were prepared from 1-hydroxy-2-naphthoic acid in nine steps with excellent yields. Twenty-four of the novel synthetic naphthoquinone esters showed significant antimalarial activity with IC(50) values in the range of 0.03-16.63 microM. The length of the aliphatic chain and the presence of C-2' substituents on the propyl chain affected the activity. Interestingly, compounds 31 and 37 showed very good antimalarial activity and were not toxic to normal Vero cells, and the PTI values of 31 (>1990.38) and 37 (1825.94) are excellent. Both 31 and 37 showed potent inhibition against P. falciparum 3D7 cyt bc(1) and no inhibition on rat cyt bc(1). They showed IC(50) values in the nanomolar range, providing full inhibition of cyt bc(1) with one molecule inhibitor bound per cyt bc(1) monomer at the Q(o) site.

Evaluating the trophic transfer of cadmium, polonium, and methylmercury in an estuarine food chain.

We examined the transfer of Cd, methylmercury (MeHg), and Po in an estuarine food chain (from phytoplankton to zooplankton [Daphnia pulex] to killifish [Fundulus heteroclitus] and, finally, to juvenile striped bass [Morone saxatilis]) to better understand both the extent to which these elements may biomagnify and the underlying mechanisms governing this biomagnification. Among the phytoplankton examined (Cyclotella meneghiniana and Chlamdomonas reinhardtii), metal uptake was rapid, and volume concentration factors for all metals reached values between 10(4) and 10(5). The resulting assimilation efficiencies (AEs) of ingested metals in all animals were highest for MeHg, with values greater than 76%. The AEs of Cd were 21 to 33% in D. pulex, 1 to 16% in F. heteroclitus, and 38 to 56% in M. saxatilis. Polonium AEs were 69 to 87% in D. pulex, 25 to 41% in F. heteroclitus, and 9 to 21% in M. saxatilis. Loss rate constants (ke) of metals in D. pulex ranged from 0.04/d for MeHg to 0.39/d for Po; metal ke values for F. heteroclitus ranged from 0.01 to 0.02/d. Using a kinetic model, we showed that the trophic transfer factor, defined as the ratio of metal concentration in predatory animals to metal concentration in prey organisms, was greater than unity for all three metals in D. pulex feeding on phytoplankton, suggesting that these metals may be biomagnified at this trophic step. In killifish feeding on D. pulex, the trophic transfer factor was consistently greater than one for MeHg, consistently less than one for Cd, and from 0.1 to 1.4 for Po, suggesting that both MeHg and Po have the potential to biomagnify at this trophic step.

Rapid mobilization of functional donor hematopoietic cells without G-CSF using AMD3100, an antagonist of the CXCR4/SDF-1 interaction.

Allografts from HLA-matched sibling donors were mobilized and collected without granulocyte colony-stimulating factor (G-CSF) using AMD3100, a direct antagonist of CXCR4/stromal-derived factor 1 (SDF-1/CXCL12). Donors (N = 25) were treated with AMD3100 at a dose of 240 mug/kg by subcutaneous injection, and leukapheresis was then initiated just 4 hours later. Two-thirds of the donors collected an allograft with a CD34(+) cell dose sufficient for transplantation after just one dose of AMD3100. No donor experienced more than grade 1 toxicity. After a myeloablative regimen, 20 patients with hematologic malignancies received allografts collected after AMD3100 alone. All patients engrafted neutrophils (median day 10) and platelets (median day 12) promptly. Acute graft-versus-host disease (GVHD) grades 2 through 4 occurred in 35% of patients. One patient died due to complications related to acute GVHD. No unexpected adverse events were observed in any of the recipients. All 14 patients surviving in remission have robust trilineage hematopoiesis and are transfusion-free with a median follow-up of 277 days (range, 139-964 days). Direct antagonism of CXCR4 by AMD3100 may provide a more rapid and possibly less toxic and cumbersome alternative to traditional G-CSF-based mobilization in normal donors. This trial was registered as no. NCT00241358 at www.ClinicalTrials.gov.

Pharmacokinetics of decitabine administered as a 3-h infusion to patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS).

PURPOSE: In this study, pharmacokinetics (PK) of decitabine administered as a 3-h intravenous infusion of 15 mg/m2 every 8 h for 3 days (cycles repeated every 6 weeks) was evaluated in patients with MDS or AML. METHODS: The PK of this dosing regimen was evaluated in sixteen patients with MDS or AML. Plasma samples were obtained pre-dose and during the first 8-h dosing interval on each dosing day during Cycle 1, and at pre-dose and just prior to the end of infusion during Cycle 2. PK samples were assayed for decitabine by a sensitive and specific validated liquid chromatography-tandem mass spectrometry method. RESULTS: The mean maximum observed plasma concentration (Cmax), 64.8-77.0 ng/ml, and the mean area under the plasma concentration-time curve (AUC0-infinity), 152-163 ng h/ml, were unchanged during dosing of decitabine for 3 days. The time to the maximum concentration (Tmax) generally occurred at the end of infusion. The mean values for terminal phase elimination half-life (0.62-0.78 h), total body clearance (125-132 l/h per m2), and volume of distribution at steady state (62.7-89.2 l/m2), remained unchanged during the every 8 h dosing (P>0.05). Cycles 1 and 2 Cmax values for days 1, 2, and 3 were not significantly different as determined by paired two-tailed t test (P>0.05). The primary toxicity of decitabine was myelosuppression, which was observed in all patients. Two deaths, from sepsis, were considered possibly related to decitabine. CONCLUSIONS: Decitabine dosed at 15 mg/m2 iv every 8 h for 3 days resulted in a predictable and manageable toxicity profile in patients with MDS/AML. The repeated dosing did not result in systemic accumulation of the drug, and decitabine PK remained unchanged from cycle to cycle.

Bortezomib inhibits osteoclast activity in patients with multiple myeloma.

BACKGROUND: The antimyeloma agent bortezomib functions as an inhibitor of nuclear factor (NF)-kappaB. Although NF-kappaB inhibition is predicted to affect osteoclast function, preclinical and clinical studies have primarily reported an effect on osteoblasts. PATIENTS AND METHODS: We examined parameters of bone turnover prospectively in patients with multiple myeloma treated with bortezomib before and after autologous transplantation. Thirty-nine patients received 2 cycles of bortezomib on days 1, 4, 8, and 11 of a 21-day cycle. After high-dose melphalan with autologous stem cell transplantation, bortezomib 1.3 mg/m2 on days 1, 8, 15, and 22 of a 5-week cycle was administered as maintenance therapy. RESULTS: During posttransplantation bortezomib, decreases in the urinary excretion of collagen N-telopeptide indicated that bortezomib suppresses osteoclast function. CONCLUSION: The effects on osteoclasts occurred in the absence of bisphosphonate treatment and independently of changes in monoclonal protein levels. Further studies exploring the role of bortezomib as a bone protective agent could be warranted.

A mitochondrial cytochrome b mutation causing severe respiratory chain enzyme deficiency in humans and yeast.

Whereas the majority of disease-related mitochondrial DNA mutations exhibit significant biochemical and clinical heterogeneity, mutations within the mitochondrially encoded human cytochrome b gene (MTCYB) are almost exclusively associated with isolated complex III deficiency in muscle and a clinical presentation involving exercise intolerance. Recent studies have shown that a small number of MTCYB mutations are associated with a combined enzyme complex defect involving both complexes I and III, on account of the fact that an absence of assembled complex III results in a dramatic loss of complex I, confirming a structural dependence between these two complexes. We present the biochemical and molecular genetic studies of a patient with both muscle and brain involvement and a severe reduction in the activities of both complexes I and III in skeletal muscle due to a novel mutation in the MTCYB gene that predicts the substitution (Arg318Pro) of a highly conserved amino acid. Consistent with the dramatic biochemical defect, Western blotting and BN-PAGE experiments demonstrated loss of assembled complex I and III subunits. Biochemical studies of the equivalent amino-acid substitution (Lys319Pro) in the yeast enzyme showed a loss of enzyme activity and decrease in the steady-state level of bc1 complex in the mutant confirming pathogenicity.