Is accelerated oxidation of lactate required for dichloroacetate to lower the level of lactate in blood?

We examined mechanisms by which dichloroacetate (DCA), an activator of pyruvate dehydrogenase (PDH), led to a decrease in the concentration of lactate in blood in a unique "metabolic setting," where the concentration of lactate in blood was 5.4 +/- 0.5 mmol/L. Elevated levels of lactate were induced in anaesthetized rabbits by the administration of a large dose of insulin. The rate of consumption of oxygen was 1.2 +/- 0.1 mmol/min, the respiratory quotient was close to unity, and close to half of the PDH was in its active form; therefore, virtually all ATP synthesis should require flux through PDH. Hence, we predicted that DCA should not cause a significant decrease in the concentration of lactate in blood in this model. In contrast, if DCA was effective, new insights could be obtained into its mechanisms of action, at least in this setting. During steady-state hyperlactatemia, DCA was given as its sodium salt, 2 mmol/kg (n = 10); a control group (n = 5) received equimolar NaCl. Forty minutes later, the level of lactate in blood in the DCA group was 1.3 +/- 0.2 mmol/L, significantly lower than in the NaCl group (4.2 +/- 0.6 mmol/L). To determine the organ(s) responsible for removing lactate, arteriovenous differences were measured in organs drained by the jugular, femoral, and hepatic veins. There was no net uptake of lactate in these drainage beds after DCA was administered. From a quantitative analysis of the rate of removal of lactate and the rate of consumption of oxygen, it seems unlikely that the majority of the decrease in lactate could be directly attributed to an increase in its oxidation.     

Antithyroid drug therapy for Graves' hyperthyroidism: is long-term administration of a small maintenance dose necessary?

This retrospective study serves as an inquiry into the common practice of long-term administration of small maintenance doses of either methyl-mercaptoimidazole (MMI) or propylthiouracil (PTU) to Graves' hyperthyroid patients who became euthyroid with primary large doses of the same drugs. One hundred and two patients with Graves' hyperthyroidism treated with antithyroid drug (ATD) were studied. Sixty-one were treated with conventional long term therapy and 41 were treated with short-term therapy. Small maintenance doses of ATDs were not administered to the short-term therapy patients. The duration of long-term therapy was 28.6 +/- 20.2 months (from 12 to 48 months) and that of short-term therapy was 8.4 +/- 1.8 months (from 5 to 11). Post therapy and follow-up observation continued for 19.0 +/- 2.7 months (16-25 months) in both long-term and short-term patients. Of the 61 long-term therapy patients, 20 were relapsed and 41 (67.2%) continue to remain in remission. So too, of the 41 short-term therapy patients, 14 relapsed and 27 (65.9%) still remain in remission. There was no statistical difference between the long-term and short-term therapy group in age, sex, duration of symptoms before diagnosis, antithyroid antibodies, radioactive iodine uptake, free thyroid hormone levels or goiter size before treatment or in TBII levels at cessation of ATD. It is concluded that 'short-term ATD therapy' without a maintenance dose is sufficient and saves several months of the patient's and clinician's time.     

Regeneration therapy of pancreatic beta cells: towards a cure for diabetes?

Regeneration therapy is an approach which could potentially move us towards a cure for type 1 diabetes. It is classified into three categories: (1) In vitro regeneration therapy using transplanted cultured cells, including ES cells, pancreatic stem cells, and beta-cell lines, in conjunction with immunosuppressive therapy or immunoisolation. (2) In ex vivo regeneration therapy, patients' own cells, such as bone marrow stem cells, are transiently removed and induced to differentiate into beta cells in vitro. At present, however, insulin-producing cells cannot be generated from bone marrow stem cells. (3) In in vivo regeneration therapy, impaired tissues regenerate from patients' own cells in vivo. beta-Cell neogenesis from non-beta-cells and beta-cell proliferation in vivo have been considered, particularly as regeneration therapies for type 2 diabetes. Regeneration therapy of pancreatic beta cells can be combined with various other therapeutic strategies, including islet transplantation, cell-based therapy, gene therapy, and drug therapy to promote beta-cell proliferation and neogenesis, and it is hoped that these strategies will, in the future, provide a cure for diabetes.     

Dyspepsia: is a trial of therapy appropriate?

Dyspepsia is a common, benign condition that may be distinguished from gastroesophageal reflux, irritable bowel syndrome and pancreatobiliary, coronary or musculoskeletal disease by a careful history and physical examination. However, the presence or absence of a peptic ulcer in dyspepsia can be determined only by an endoscopic examination or a barium-contrast radiograph. Although the American College of Physicians has recommended trying drug therapy for patients with dyspepsia before diagnostic tests are done, new data support early diagnosis. Although therapy is initially cheaper than endoscopic examination, over a year the costs even out because most patients with dyspepsia eventually need an endoscopic examination, and many patients with nonulcer dyspepsia are given medication unnecessarily. Endoscopic examination, if available to general practitioners, is the most cost-effective approach to dyspepsia. An approach that does not include endoscopy lacks the opportunity to offer patients convincing reassurance that their illness is not serious, which is arguably the most important treatment in cases of nonulcer dyspepsia. Studies supporting the use of endoscopic examination predate the treatment of peptic ulcers with antibiotics, which makes an initial endoscopic examination to determine whether the patient has an ulcer even more important.     

Quorum-sensing control in Staphylococci -- a target for antimicrobial drug therapy?

Today, we find ourselves in an urgent need for novel antibacterial drugs, as many important human pathogens have acquired multiple antibiotic resistance factors. Among those, Staphylococcus aureus and S. epidermidis play a major role as the leading sources of nosocomial infections. Recently, it has been suggested to develop therapeutics that attack bacterial virulence rather than kill bacteria. Such drugs are called "antipathogenic" and are believed to reduce the development of antibiotic resistance. Specifically, cell-density-dependent gene regulation (quorum-sensing) in bacteria has been proposed as a potential target. While promising reports exist about quorum-sensing blockers in gram-negative bacteria, the use of the staphylococcal quorum-sensing system as a drug target is now seen in an increasingly critical way. Inhibition of quorum-sensing in Staphylococcus has been shown to enhance biofilm formation. Furthermore, down-regulation or mutation of the Staphylococcus quorum-sensing system increases bacterial persistence in device-related infection, suggesting that interference with quorum-sensing would enhance rather than suppress this important type of staphylococcal disease. The chemical nature and biological function of another proposed staphylococcal quorum-sensing inhibitor, named "RIP", are insufficiently characterized. Targeting quorum-sensing systems might in principle constitute a reasonable way to find novel antibacterial drugs. However, as outlined here, this approach requires careful investigation in every specific pathogen and type of infection.     

Influence of body mass, age, and maturation on specific oxygen consumption in a freshwater cichlid fish, Cichlasoma nigrofasciatum (Günther, 1869)

The oxygen consumption of a freshwater convict cichlid (Cichlasoma nigrofasciatum) was determined throughout the fish development from age 74 days to 403 days, covering the period before and after maturation. The specific oxygen consumption decreases with increasing age. The decrease in metabolic rate appears rather in distinct phases. A small increase in the average specific metabolic rate (mainly from the bigger fish) around age 200 days suggests an involvement of internal changes in the fish during a transition period from "young" state to "mature" state. The relationship between the specific oxygen consumption and body mass is determined by maturation and age. Before reaching maturation (before age 200 days) the correlation between specific oxygen consumption and body mass is negative for "young" fish of the same age. After age 200 days, no correlation between both parameters could be found. We suggest from this study that both factors "age" and "size" of the organism have to be considered for determining the metabolism, especially in fish. This study indicates that even in fish, which retain a continuous growing capability until they die, the decrease in the specific oxygen consumption is related to the aging process.     

Commercial production of β-glucuronidase (GUS): a model system for the production of proteins in plants

We have generated transgenic maize seed containing -glucuronidase(GUS) for commercial production. While many other investigators have demonstrated the expression of GUS as a scoreable marker, this is one of the first cases where a detailed characterization of the transgenic plants and the protein were performed which are necessary to use this as a commercial source of GUS. The recombinant -glucuronidase was expressed at levels up to 0.7% of water-soluble protein from populations of dry seed, representing one of the highest levels of heterologous proteins reported for maize. Southern blot analysis revealed that one copy of the gene was present in the transformant with the highest level of expression. In seeds, the majority of recombinant protein was present in the embryo, and subcellular localization indicated that the protein was dispersed throughout the cytoplasm. The purified recombinant -glucuronidase (GUS) was compared to native -glucuronidase using SDS-PAGE and western blot analysis. The molecular mass of both the recombinant and native enzymes was 68 000 Da. N-terminal amino acid sequence of the recombinant protein was similar to the sequence predicted from the cloned Escherichia coli gene except that the initial methionine was cleaved from the recombinant GUS. The recombinant and native GUS proteins had isoelectric points (pI) from 4.8 to 5.0. The purified proteins were stable for 30 min at 25, 37, and 50 ° C. Kinetic analysis of the recombinant and native GUS enzymes using 4-methylumbelliferyl glucuronide (MUG) as the substrate was performed. Scatchard analysis of these data demonstrated that the recombinant enzyme had a K_m of 0.20 mM and a V_max of 0.29 mM MUG per hour, and the native enzyme had a K_m and V_max of 0.21 mM and 0.22 mM/h respectively. Using D-saccharic acid 1,4-lactone, which is an inhibitor of -glucuronidase, the K_i of the native and recombinant enzymes was determined to be 0.13 mM. Thus, these data demonstrate that recombinant GUS is functionally equivalent to native GUS. We have demonstrated the expression of high levels of GUS can be maintained in stable germlines and have used an efficient recovery system where the final protein product, GUS, has been successfully purified. We describe one of the first model systems for the commercial production of a foreign protein which relies on plants as the bioreactor.     

Is peak postprandial oxygen consumption positively related to growth rate and resting oxygen consumption in a sedentary catfish Silurus meridionalis?

The resting oxygen consumption     , postprandial and post-exercise peak oxygen consumption     of 137 juvenile southern catfish Silurus meridionalis , weighing 18·5 ± 0·8 g (mean ± s . d .), were measured at 25° C to determine whether     is positively related to postprandial and post-exercise     in sedentary S. meridionalis . In addition, postprandial metabolic response [ i.e. the specific dynamic action (SDA)] after a satiating meal and the growth performance as a consequence of a 3 week feeding-growth trail were measured in 40 S. meridionalis , weighing 14·3 ± 0·2 g, at 25° C to determine whether postprandial     is positively related to growth rate. Postprandial     was positively correlated with     , while post-exercise     was not. Both postprandial     and post-exercise     were positively correlated with factorial and absolute scope. There was no significant correlation between the growth rate and postprandial     in S. meridionalis . It suggested that as a sit-and-wait forager with low     , low post-exercise     and high postprandial     , the expenditure of energy for maintenance in S. meridionalis may be more closely related to digestive processes than locomotor activities.     

What is a suitable management for Typha latifolia control in wet meadows?

Aim

Typha latifolia causes serious problems in wet meadows by overgrowing and suppressing other native plants. To determine suitable management for T. latifolia control, we addressed the following question: What are the effects of long-term cutting at different frequencies (once or twice per year and no management) and biomass removal on cover and other characteristics of T. latifolia, and on sward productivity and plant species composition?

Location

Malá Strana nature reserve, Jizerské hory Mountains, Czechia.

Methods

A long-term experiment arranged in a randomised block design with three blocks was established in 2005. Data were collected from five treatments: unmanaged control; cutting once a year in June without biomass removal and with biomass removal; cutting twice per year in June and August without biomass removal and with biomass removal. Percentage cover of T. latifolia and other vascular plant species was visually estimated and T. latifolia characteristics (tiller density, height, dry-matter biomass [DMB] yield and litter), sward height and DMB yield were measured during 2005–2018 at the end of June.

Results and Discussion

Regular cutting once or twice per year regardless of cut biomass removal led to reductions in tiller density, height, litter and DMB yield of T. latifolia. Biomass removal had only a slight tendency to affect T. latifolia characteristics. The higher frequency of cutting significantly decreased the mean T. latifolia cover, litter and DMB yield. Cutting once or twice per year regardless of biomass removal led to successive changes in plant species composition but had no effect on the species richness and evenness.

Conclusions

Cutting at least once per year without biomass removal seems to be sufficient to achieve a decrease in DMB yield and litter of T. latifolia plants, and thereby maintain the wet-meadow vegetation without loss of species richness and also preventing the overgrowth of shrubs and trees.     

Effects of tobacco smoke on IL-16 in CD8+ cells from human airways and blood: a key role for oxygen free radicals?

Chronic exposure to tobacco smoke leads to an increase in the frequency of infections and in the number of CD8(+) and CD4(+) cells as well as the CD4(+) chemoattractant cytokine IL-16 in the airways. Here, we investigated whether tobacco smoke depletes intracellular IL-16 protein and inhibits de novo production of IL-16 in CD8(+) cells from human airways and blood while increasing extracellular IL-16 and whether oxygen free radicals (OFR) are involved. Intracellular IL-16 protein in CD8(+) cells and mRNA in all cells was decreased in bronchoalveolar lavage (BAL) samples from chronic smokers. This was also the case in human blood CD8(+) cells exposed to water-soluble tobacco smoke components in vitro, in which oxidized proteins were markedly increased. Extracellular IL-16 protein was increased in cell-free BAL fluid from chronic smokers and in human blood CD8(+) cells exposed to water-soluble tobacco smoke components in vitro. This was not observed in occasional smokers after short-term exposure to tobacco smoke. A marker of activation (CD69) was slightly increased, whereas other markers of key cellular functions (membrane integrity, apoptosis, and proliferation) in human blood CD8(+) cells in vitro were negatively affected by water-soluble tobacco smoke components. An OFR scavenger prevented these effects, whereas a protein synthesis inhibitor, a β-adrenoceptor, a glucocorticoid receptor agonist, a phosphodiesterase, a calcineurin phosphatase, and a caspase-3 inhibitor did not. In conclusion, tobacco smoke depletes preformed intracellular IL-16 protein, inhibits its de novo synthesis, and distorts key cellular functions in human CD8(+) cells. OFR may play a key role in this context.     

Natural extracellular nanovesicles and photodynamic molecules: is there a future for drug delivery?

Photodynamic molecules represent an alternative approach for cancer therapy for their property (i) to be photo-reactive; (ii) to be not-toxic for target cells in absence of light; (iii) to accumulate specifically into tumour tissues; (iv) to be activable by a light beam only at the tumour site and (v) to exert cytotoxic activity against tumour cells. However, to date their clinical use is limited by the side effects elicited by systemic administration. Extracellular vesicles are endogenous nanosized-carriers that have been recently introduced as a natural delivery system for therapeutic molecules. We have recently shown the ability of human exosomes to deliver photodynamic molecules. Therefore, this review focussed on extracellular vesicles as a novel strategy for the delivery of photodynamic molecules at cancer sites. This completely new approach may enhance the delivery and decrease the toxicity of photodynamic molecules, therefore, represent the future for photodynamic therapy for cancer treatment.     

Stem cells: is there a future in plastics?

The concept that ostensibly tissue-specific stem cells can give rise to cells of heterologous lineages has gained support from studies using purified hematopoietic stem cells and sensitive donor-cell tracking methods. The ability to exploit these findings in clinical settings will probably depend on new insights into the mechanisms by which such stem cells or their progeny migrate to sites of organ damage and differentiate to cell types competent to participate in tissue regeneration.     

Influence of cultivation and induction conditions on β-lactamase production in Acinetobacter calcoaceticus

Summary The formation and localization of the -lactamase of Acinetobacter calcoaceticus CCM 5593 is strongly affected by cultivation and induction conditions. Optimal parameters for enzyme yield are cultivation on minimal salts medium with acetate (10 g·1^–1) as carbon source and addition of yeast extract (5–10 g·l^–1), induction by cefotaxime (50g·ml^–1) immediately after inoculation and growth for 24 h at 25° C. The strain forms a basal level of -lactamase constitutively [70 units (U)·g^–1]. Nearly all of this was found to be cell-bound. However, -lactamase activity additionally produced after induction (up to 500 U·g^–1 wet bacteria) was located in the culture medium (up to 96%). This unusual localization is a special feature of A. calcoaceticus and is not attributed to cell lysis. Offprint requests to: P. Borneleit     

Physical parameter-based allocation for the energy consumption of pyro-metallurgical system—a case study on nickel production in China

Purpose

The objectives of this study were to establish an allocation model for the energy consumption of pyro-metallurgical system based on the physical relationship between the input and output, apply the established model to nickel production in China and compare the difference between the allocation results derived from the established model and the traditional models.

Methods

The basic methodological idea of this study is that the energy input of a multi-output pyro-metallurgical process should be allocated according to how the energy input is consumed in the process. The energy consumption of pyro-metallurgical system was decomposed into different categories (e.g. energy absorption of chemical reaction and energy loss), and these categories were classified into two groups, i.e. the categories of energy consumption dependent on the product ratio (PRDE) and the categories of energy consumption independent on the product ratio (PRIE); then, the allocation basis for each category of energy consumption was determined through the physical relationship between the energy input and metal output. The allocation for the energy consumption of nickel production in China was carried out; the system boundary includes two sub-systems (i.e. Ni–Cu coproduction system and Ni refining system), and the energy consumption of the coproduction system should be allocated; the basic data required by the allocation model and the compilation of LCI were mainly obtained from literature.

Results and discussion

The energy consumption of the processes of mining, drying, converting and floating-grinding belongs to PRIE following the principle of mass-based allocation, and the corresponding allocation factors are 64, 64, 69 and 69 %, respectively. The categories of energy consumption involved in the smelting process (the key process for demonstrating the allocation model) include both PRIE and PRDE, and the aggregated allocation factor was calculated as 56 %. The allocation result derived from the established model is lower than the results derived from the mass-based model and the market value-based model, because that, through the desulphurization reactions that occurred in the smelting process, the chemical states of copper and nickel are transformed from copper pyrite (CuFeS₂) and nicopyrite ((Fe,Ni)₉S₈) into cuprous sulphide (Cu₂S) and nickel sulphide (Ni₃S₂), and copper compound releases more sulphur atoms than nickel compound. When analyzing a single pyro-metallurgical process, the result of allocation is sensitive to basis selection; however, when comparing two or more pyro-metallurgical processes, the comparison result of allocation is relatively insensitive to basis selection.

Conclusions

The energy input of pyro-metallurgical system is consumed in different physical-chemical ways; the decomposition of energy consumption is significant for choosing allocation bases; the basis of mass can only be used for the allocation of PRIE, and choosing the same allocation basis for different cases without a systematic analysis will be inappropriate. The requirement of some nontraditional extra inventory data is the major limitation of the established model. This study mainly focused on how nickel production system consumes the energy input, and the energy consumption patterns of other production systems should be taken into account in future studies.

     

Travel medicine and general practice: a suitable case for audit?

Travel medicine becomes more important with the continual expansion of international travel and the increased popularity of exotic holiday destinations. In the United Kingdom general practitioners provide the bulk of travel health advice and immunisation and there is growing interest in providing these services. While their armamentarium has been expanded with attractive but expensive new vaccines, the need for health service advice has never been more vital, with the risks of HIV infection and drug resistant malaria. Advantages of a general practice based travel medicine service include maintaining continuity of care for the patient, but a disadvantage might be that the general practitioner sees too few patients to acquire enough skill in the subject. Furthermore, there may be a conflict of interest between time devoted to the "vaccination ritual" and giving health advice. Overall there seems to be a case for both audit and support by the health authorities.