Moving towards more sustainable diets: Is there potential for a personalised approach in practice?

Discourse on the relationship between food production, healthy eating and sustainability has become increasingly prominent and controversial in recent years. Research groups often take one perspective when reporting on sustainable diets, and several often neglect considerations for the multiple aspects that make a diet truly sustainable, such as cultural acceptability, differences in nutritional requirements amongst the population and the efficiency of long-term dietary change. Plant-based diets are associated with lower greenhouse gas emissions (GHGEs) and have been linked with better health outcomes, including lower risk of diet-related chronic disease. However, foods associated with higher GHGE, such as lean red meat, fish and dairy, have beneficial nutritional profiles and contribute significantly to micronutrient intakes. Some research has shown that diets associated with lower GHGE can be less nutritionally adequate. Several countries now include sustainability recommendations in dietary guidelines but use vague language such as "increase" or "consume regularly" when referring to plant-based foods. General population-based nutrition advice has poor adherence and does not consider differences in nutritional needs. Although modelling studies show potential to significantly reduce environmental impact with dietary changes, personalising such dietary recommendations has not been studied. Adapting recommendations to the individual through reproducible methods of personalised nutrition has been shown to lead to more favourable and longer-lasting dietary changes compared to population-based nutrition advice. When considering sustainable healthy dietary guidelines, personalised feedback may increase the acceptability, effectiveness and nutritional adequacy of the diet. A personalised approach has the potential for delivering a new structure of more sustainable healthy food-based dietary guidelines. This review evaluates the potential to develop personalised sustainable healthy food-based dietary guidelines and discusses potential implications for policy and practice.

Opiorphin-dependent upregulation of CD73 (a key enzyme in the adenosine signaling pathway) in corporal smooth muscle cells exposed to hypoxic conditions and in corporal tissue in pre-priapic sickle cell mice

The precise molecular mechanisms underlying priapism associated with sickle cell disease remain to be defined. However, there is increasing evidence that up-regulated activity of the opiorphin and adenosine pathways in corporal tissue, resulting in heighted relaxation of smooth muscle, play an important role in development of priapism. A key enzyme in the adenosine pathway is CD73, an ecto-5-prime-nucleotidase (5-prime-ribonucleotide phosphohydrolase; EC 3.1.3.5) which catalyzes the conversion of adenosine mononucleotides to adenosine. In the present study we investigated how sickle cell disease and hypoxia regulate the interplay between opiorphin and CD73. In the corpora of sickle cell mice we observed significantly elevated expression of both the mouse opiorphin homologue mSmr3a (14-fold) and CD73 (2.2-fold) relative to non-sickle cell controls at a life-stage prior to the exhibition of priapism. Sickle cell disease has a pronounced hypoxic component, therefore we determined if CD73 was also modulated in in vitro corporal smooth muscle (CSM) models of hypoxia. Hypoxia significantly increased CD73 protein and mRNA expression by 1.5-fold and 2-fold, respectively. We previously demonstrated that expression of another component of the adenosine signaling pathway, the adensosine 2B receptor, can be regulated by sialorphin (the rat opiorphin homolologue), and we demonstrate that sialorphin also regulates CD73 expression in a dose and time dependent fashion. Using siRNA to knock-down sialorphin mRNA expression in CSM cells in vitro, we demonstrate that the hypoxic up-regulation of CD73 is dependent on the up-regulation of sialorphin. Overall our data provides further evidence to support a role for opiorphin in CSM in regulating the cellular response regulating response to hypoxia or sickle cell disease by activating smooth muscle relaxant pathways.

The effect of methamphetamine on an animal model of erectile function

In the US methamphetamine is considered a first-line treatment for attention-deficit hyperactivity disorder. It is also a common drug of abuse. Reports in patients and abusers suggest its use results in impotence. The efficacy of phosphodiesterase-5 inhibitors (PDE5i) to restore erectile function in these patient groups also has not been determined. In these studies, we determined if the rat is a suitable animal model for the physiological effects of methamphetamine on erectile function, and if a PDE5i (tadalafil) has an effect on erectile function following methamphetamine treatment. In acute phase studies, erectile function was measured in male Sprague-Dawley rats, before and after administration of 10 mg/kg methamphetamine i.p. Chronically treated animals received escalating doses of methamphetamine [2.5 mg/kg (1st week), 5 mg/kg (2nd week), and 10 mg/kg (3rd week)] i.p. daily for 3 weeks and erectile function compared with untreated controls. The effect of co-administration of tadalafil was also investigated in rats acutely and chronically treated with methamphetamine. Erectile function was determined by measuring the intracorporal pressure/blood pressure ratio (ICP/BP) following cavernous nerve stimulation. In both acute and chronic phase studies, we observed a significant increase in the rates of spontaneous erections after methamphetamine administration. In addition, following stimulation of the cavernous nerve at 4 and 6 mA, there was a significant decrease in the ICP/BP ratio (approximately 50%), indicative of impaired erectile function. Tadalafil treatment reversed this effect. In chronically treated animals, the ICP/BP ratio following 4 and 6 mA stimulation decreased by approximately 50% compared with untreated animals and erectile dysfunction (ED) was also reversed by tadalafil. Overall, our data suggest that the rat is a suitable animal model to study the physiological effect of methamphetamine on erectile function. Our work also provides a rationale for treating patients that report ED associated with therapeutics-containing methamphetamine or amphetamine with PDE5i.

Experimental priapism is associated with increased oxidative stress and activation of protein degradation pathways in corporal tissue

Priapism is a debilitating disease for which there is at present no clinically accepted pharmacologic intervention. It has been estimated that priapism lasting more than 24 hours in patients is associated with a 44–90% rate of erectile dysfunction (ED). In this investigation we determined in two animal models of priapism (opiorpin-induced priapism in the rat and priapism in a mouse model of sickle cell disease) if there is evidence for an increase in markers of oxidative stress in corporal tissue. In both animal models we demonstrate that priapism results in increased levels of lipid peroxidation, glutathione S-transferase activity, and oxidatively damaged proteins in corporal tissue. Using Western blot analysis we demonstrated there is up regulation of the ubiquitination ligase proteins, Nedd-4 and Mdm-2, and the lysososomal autophage protein, LC3. The anti-apoptotic protein, Bcl-2, was also up regulated. Overall, we demonstrate that priapism is associated with increased oxidative stress in corporal tissue and the activation of protein degradation pathways. Since oxidative stress is known to mediate the development of ED resulting from several etiologies (for example ED resulting from diabetes and aging) we suggest that damage to erectile tissue resulting from priapism might be prevented by treatments targeting oxidative stress.

Ageing causes cytoplasmic retention of MaxiK channels in rat corporal smooth muscle cells

The MaxiK channel plays a critical role in the regulation of corporal smooth muscle tone and thereby erectile function. Given that ageing results in a decline in erectile function, we determined changes in the expression of MaxiK, which might impact erectile function. Quantitative-polymerase chain reaction demonstrated that although there is no significant change in transcription of the alpha- and beta-subunits that comprise the MaxiK channel, there are significant changes in the expression of transcripts encoding different splice variants. One transcript, SV1, is 13-fold increased in expression in the ageing rat corpora. SV1 has previously been reported to trap other isoforms of the MaxiK channel in the cytoplasm. Correlating with increased expression of SV1, we observed in older rats there is approximately a 13-fold decrease in MaxiK protein in the corpora cell membrane and a greater proportion is retained in the cytoplasm (approximately threefold). These experiments demonstrate that ageing of the corpora is accompanied by changes in alternative splicing and cellular localization of the MaxiK channel.

The successful long-term treatment of age related erectile dysfunction with hSlo cDNA in rats in vivo

PURPOSE

We have previously reported that 1 intracorporeal injection of 100 microg hSlo/pcDNA reversed the effect of aging on erectile function in a rat model in vivo for at least 2 months. We report our further investigations of the amplitude, duration and physiological relevance of this novel gene transfer approach.

MATERIALS AND METHODS

A total of 191 retired breeder Sprague-Dawley rats were given a single intracavernous injection of phosphate buffered saline, 1,000 microg pcDNA, or 10, 100 or 1,000 microg pcDNA/hSlo. The animals were studied 1 to 6 months after injection. The intracorporeal pressure (ICP) response to cavernous nerve stimulation and immunostaining as well as hematoxylin and eosin staining were done to evaluate effector nerve integrity and tissue histology, respectively.

RESULTS

Gene transfer prevented an age related decrease in resting ICP and a physiologically relevant, significant effect on normalizing erection in vivo, as determined by submaximal (0.5 mA) and maximal (4.0 mA) cavernous nerve stimulation. The effects were observed 1 month after transfection and sustained for 6 months at the 100 and 1,000 microg doses of pcDNA/hSlo (p <0.026).

CONCLUSIONS

The physiological manifestations of gene transfer were detected as an amelioration of the age related decrease in resting ICP, and parallel increase in the magnitude of the cavernous nerve stimulated an ICP response to a level at which visible erections were again observed in this rat model of aging in vivo.

The physiology, pathophysiology and therapeutic potential of gap junctions in smooth muscle

Phenotypic variability in smooth muscle cells accounts, in large part, for the incredible functional diversity required of the involuntary hollow organs of the body (i.e., respiratory passages, blood vessels, gastrointestinal tract, urogenital tract, etc.). In all instances coordination of smooth muscle cell responses, that is, contraction and relaxation, is critical to normal organ function. While numerous biological mechanisms exist for coordinating smooth muscle cell responses, intercellular communication through gap junctions represents a common denominator present in all organ systems. In this report, we review the evidence documenting the presence and functional significance of myocyte gap junctions to physiologically distinct organ systems, and furthermore, provide some examples of their putative roles in organ pathology. Finally, we advance the thesis that despite their ubiquity and heterogeneous expression, gap junctions are nonetheless potentially attractive therapeutic targets for the treatment of certain smooth muscle disorders. Their therapeutic efficacy will necessarily hinge on the existence of connexin isoform-selective junctional effects. The overall rationale for targeting the intercellular pathway is therefore analogous to strategies that target other ubiquitously expressed ion channels, such as calcium or potassium channels. Such strategies have proved efficacious for the treatment of a wide range of human smooth muscle disorders including hypertension, urinary incontinence and sexual function.

c-MYC interacts with INI1/hSNF5 and requires the SWI/SNF complex for transactivation function

Chromatin organization plays a key role in the regulation of gene expression. The evolutionarily conserved SWI/SNF complex is one of several multiprotein complexes that activate transcription by remodelling chromatin in an ATP-dependent manner. SWI2/SNF2 is an ATPase whose homologues, BRG1 and hBRM, mediate cell-cycle arrest; the SNF5 homologue, INI1/hSNF5, appears to be a tumour suppressor. A search for INI1-interacting proteins using the two-hybrid system led to the isolation of c-MYC, a transactivator. The c-MYC-INI1 interaction was observed both in vitro and in vivo. The c-MYC basic helix-loop-helix (bHLH) and leucine zipper (Zip) domains and the INI1 repeat 1 (Rpt1) region were required for this interaction. c-MYC-mediated transactivation was inhibited by a deletion fragment of INI1 and the ATPase mutant of BRG1/hSNF2 in a dominant-negative manner contingent upon the presence of the c-MYC bHLH-Zip domain. Our results suggest that the SWI/SNF complex is necessary for c-MYC-mediated transactivation and that the c-MYC-INI1 interaction helps recruit the complex.

Manipulation of the vsg co-transposed region increases expression-site switching in Trypanosoma brucei

Disruption of a region of DNA in Trypanosoma brucei immediately upstream of the expressed telomere-proximal variant surface glycoprotein gene (vsg), known as the co-transposed region (CTR), can cause a dramatic increase in the rate at which the active expression site (ES) is switched off and a new ES is switched on. Deletion of most of the CTR in two ESs caused a greater than 100-fold increase in the rate of ES switching, to about 1.3 x 10(-4) per generation. A more dramatic effect was observed when the entire CTR and the 5' coding region of the expressed vsg221 were deleted. In this case a new ES was activated within a few cell divisions. This switch also occurred in cell lines where a second vsg had been inserted into the ES, prior to CTR deletion. These cell lines, which stably co-expressed the inserted and endogenous Vsgs, in equal amounts, did not differ from the wild-type in growth rate or switching frequency, suggesting that simultaneous expression of two Vsgs has no intrinsic effect. CTR deletion did not disturb the inserted vsg117. We tentatively conclude that it was not the disruption of the vsg221 in itself that destabilized the ES. All of the observed switches occurred without additional detectable DNA rearrangements in the switched ES. Deletion of the 70-bp repeats and/or a vsg pseudogene upstream of the CTR did not affect ES stability. Several speculative interpretations of these observation are offered, the most intriguing of which is that the CTR plays some role in modulating chromatin conformation at an ES.

Stable expression of mosaic coats of variant surface glycoproteins in Trypanosoma brucei

The paradigm of antigenic variation in parasites is the variant surface glycoprotein (VSG) of African trypanosomes. Only one VSG is expressed at any time, except for short periods during switching. The reasons for this pattern of expression and the consequences of expressing more than one VSG are unknown. Trypanosoma brucei was genetically manipulated to generate cell lines that expressed two VSGs simultaneously. These VSGs were produced in equal amounts and were homogeneously distributed on the trypanosome surface. The double-expressor cells had similar population doubling times and were as infective as wild-type cells. Thus, the simultaneous expression of two VSGs is not intrinsically harmful.

Activity, mechanism of action and pharmacokinetics of 2-tert-butylbenzothiazole and CGP 6140 (amocarzine) antifilarial drugs

A variety of recently developed drugs, designed to be used in antifilarial chemotherapy, contain a thiocarbonylamide group as a common structural element. One group of these compounds is based on a 2-tert-butylbenzothiazole ring in which the carbonylamide linkage is present as an isothiocyanate, dithiocarbamic acid ester or thiourea derivative. The single representative of another series is an N-methylpiperazine adduct of amoscanate (CGP 6140 or amocarzine). CGP 6140 is currently undergoing clinical trials in patients suffering from onchocercosis. All of the drugs with antifilarial activity affect the motility of filarial worms in vitro. The primary site of action of most of these compounds is the mitochondrion. The drugs result in the swelling of this organelle and also the inhibition of respiration and other associated metabolic functions. The dithiocarbamic acid esters (e.g., CGP 20376) are devoid of intrinsic antifilarial activity. Activity of these compounds requires conversion to the corresponding isothiocyanates. This occurs spontaneously in aqueous solution at physiological pH. The thiourea compounds were found to inhibit acetylcholinesterase activity by competing with its substrate. There is also evidence that the latter drugs are metabolized by a host-derived enzyme to their isothiocyanate analogs. CGP 6140 affects both mitochondrial function and acetylcholinesterase activity. The biochemical effects of the antifilarial compounds were not found to be significantly different between mammalian and parasite test systems. Biochemical and pharmacokinetic studies suggest that the selective toxicity of the new series of drugs towards filarial parasites is most likely preferential drug uptake by the pathogen. The lack of a unique target for these compounds in the parasite may explain the side-effects seen upon their administration to humans.

High-resolution mapping of the X-linked hypohidrotic ectodermal dysplasia (EDA) locus

The X-linked hypohidrotic ectodermal dysplasia (EDA) locus has been previously localized to the subchromosomal region Xq11-q21.1. We have extended our previous linkage studies and analyzed linkage between the EDA locus and 10 marker loci, including five new loci, in 41 families. Four of the marker loci showed no recombination with the EDA locus, and six other loci were also linked to the EDA locus with recombination fractions of .009-.075. Multipoint analyses gave support to the placement of the PGK1P1 locus proximal to the EDA locus and the DXS453 and PGK1 loci distal to EDA. Further ordering of the loci could be inferred from a human/rodent somatic cell hybrid derived from an affected female with EDA and an X;9 translocation and from studies of an affected male with EDA and a submicroscopic deletion. Three of the proximal marker loci, which showed no recombination with the EDA locus, when used in combination, were informative in 92% of females. The closely linked flanking polymorphic loci DXS339 and DXS453 had heterozygosities of 72% and 76%, respectively, and when used jointly, they were doubly informative in 52% of females. The human DXS732 locus was defined by a conserved mouse probe pcos169E/4 (DXCrc169 locus) that cosegregates with the mouse tabby (Ta) locus, a potential homologue to the EDA locus. The absence of recombination between EDA and the DXS732 locus lends support to the hypothesis that the DXCrc169 locus in the mouse and the DXS732 locus in humans may contain candidate sequences for the Ta and EDA genes, respectively.

The role of amino acids in the energy generating pathways of Litomosoides carinii

The filarial parasite Litomosoides carinii was able to survive for longer than 15 h in basic filarial medium (BFM) containing either glutamine or alanine as a sole substrate. The filariids were more motile in BFM containing glucose, but even higher motility was recorded in media containing both glucose and glutamine. Incubations under aerobic conditions showed that radiolabelled glutamine was metabolised primarily to CO2. In addition, small amounts of lactate and acetate were excreted in almost equimolar quantities. Incubations where both glutamine and glucose were present demonstrated that the glutamine carbon utilised by the parasite could be completely recovered in the above three end products. The glutamine nitrogen could be recovered in the additional excretory products, alanine and ammonia. The glutamine-dependent viability of L. carinii was affected by known inhibitors of the mitochondrial respiratory chain. Glucose utilisation, and the production of CO2 from this substrate, were greatly stimulated by the presence of glutamine in the external medium. Various carbon balance studies, in conjunction with enzymatic analyses, suggest that in L. carinii, glutamine provides an input of carbon into the tricarboxylic acid (TCA) cycle, probably at the level of alpha-ketoglutarate. This increased availability of Krebs cycle intermediates will stimulate the rate of pyruvate oxidation via acetyl-CoA and the TCA cycle, and thus increase the rate of carbon flux through glycolysis. The energetic advantage associated with the utilisation of the glucose/glutamine substrate couple may explain the worm's enhanced motor activity compared to incubations with glucose as the sole energy source. Alanine was found to be degraded by the filariid to equivalent amounts of lactate, acetate and CO2, indicating a relatively low energetic efficiency. There was no detectable uptake of glutamate. A variety of other amino acids tested were neither metabolised nor able to maintain worm viability in vitro.

Litomosoides carinii: mode of action in vitro of benzothiazole and amoscanate derivatives with antifilarial activity

It is suggested that the recently developed benzothiazole and amoscanate derivatives with antifilarial activity exert their action in vitro by an inhibition of mitochondrial-derived respiration. It was confirmed that the drugs CGP 20376, 21835, 20308, 21306, and 6140 cause a rapid immobilization in vitro of the adult filarial worm, Litomosoides carinii, the time required being similar to rotenone at the same concentration. The other drugs investigated, CGPs 20309, 21833, 24589, 23518, and 13231, were also effective; however, they required much longer incubation times. Submitochondrial particles (SMP) were prepared from Ascaris muscle and rat liver. The concentration of drug causing 50% inhibition of respiration (IC50) was calculated. It was found that the drugs most rapidly inhibiting respiration have IC50s for NADH oxidase of less than 25 microM in both Ascaris and rat liver SMP. This effect on SMP respiration could be overcome by using succinate as a substrate, indicating the site of inhibition to be within complex I of the mitochondrial respiratory chain. Further experiments showed that whereas the respiratory chain's NADH:ferricyanide reductase was unaffected by these drugs, there were pronounced effects on both Ascaris and rat liver NADH:quinone reductase activity. This suggests that the inhibition within complex I occurs after the flavoprotein dehydrogenase, but before the site of the quinone reduction. The other compounds examined, which had a slower effect on motility, also showed inhibition of the NADH oxidase, but not to as great an extent as the aforementioned compounds. The compounds most active against motility were also most effective at inhibiting respiration in intact adult L. carinii. Analysis of the aerobic end products produced by L. carinii showed that acetate production was greatly reduced even in the presence of low concentrations of the drugs. There was also a slight decrease in lactate production. However, a direct effect on the glycolytic pathway was ruled out by two observations. One, that the production of lactate from cell-free extracts of L. carinii is unaffected by the presence of the drugs, and secondly, that a protozoan, Giardia lamblia, reliant on glycolysis for energy production, can survive for long periods of time in the presence of high concentrations of the drugs. A correlation can be observed between the time for immobilization of the filarial worm and the strength of inhibition of mitochondrial respiration. Therefore, it is suggested that, at least in vitro, the mechanism of toxicity of these antifilarials in L. carinii is due to the blocking of the respiratory chain at a site similar to that of rotenone.