Evolutionary and ecological forces that shape the bacterial communities of the human gut.

Since microbes were first described in the mid-1600s, we have come to appreciate that they live all around and within us with both beneficial and detrimental effects on nearly every aspect of our lives. The human gastrointestinal tract is inhabited by a dynamic community of trillions of bacteria that constantly interact with each other and their human host. The acquisition of these bacteria is not stochastic but determined by circumstance (environment), host rules (genetics, immune state, mucus, etc), and dynamic self-selection among microbes to form stable, resilient communities that are in balance with the host. In this review, we will discuss how these factors lead to formation of the gut bacterial community and influence its interactions with the host. We will also address how gut bacteria contribute to disease and how they could potentially be targeted to prevent and treat a variety of human ailments.

Endogenous α-calcitonin-gene-related peptide promotes exercise-induced, physiological heart hypertrophy in mice.

AIM: It is unknown how the heart distinguishes various overloads, such as exercise or hypertension, causing either physiological or pathological hypertrophy. We hypothesize that alpha-calcitonin-gene-related peptide (αCGRP), known to be released from contracting skeletal muscles, is key at this remodelling. METHODS: The hypertrophic effect of αCGRP was measured in vitro (cultured cardiac myocytes) and in vivo (magnetic resonance imaging) in mice. Exercise performance was assessed by determination of maximum oxygen consumption and time to exhaustion. Cardiac phenotype was defined by transcriptional analysis, cardiac histology and morphometry. Finally, we measured spontaneous activity, body fat content, blood volume, haemoglobin mass and skeletal muscle capillarization and fibre composition. RESULTS: While αCGRP exposure yielded larger cultured cardiac myocytes, exercise-induced heart hypertrophy was completely abrogated by treatment with the peptide antagonist CGRP(8-37). Exercise performance was attenuated in αCGRP(-/-) mice or CGRP(8-37) treated wild-type mice but improved in animals with higher density of cardiac CGRP receptors (CLR-tg). Spontaneous activity, body fat content, blood volume, haemoglobin mass, muscle capillarization and fibre composition were unaffected, whereas heart index and ventricular myocyte volume were reduced in αCGRP(-/-) mice and elevated in CLR-tg. Transcriptional changes seen in αCGRP(-/-) (but not CLR-tg) hearts resembled maladaptive cardiac phenotype. CONCLUSIONS: Alpha-calcitonin-gene-related peptide released by skeletal muscles during exercise is a hitherto unrecognized effector directing the strained heart into physiological instead of pathological adaptation. Thus, αCGRP agonists might be beneficial in heart failure patients.

Comprehensive Approach to Lower Blood Pressure (CALM-BP): a randomized controlled trial of a multifactorial lifestyle intervention.

Complementary medicine advocates the use of a multifactorial approach to address the varied aspects of hypertension. The aim of this study was to compare the blood pressure (BP) effect and medication use of a novel Comprehensive Approach to Lowering Measured Blood Pressure (CALM-BP), based on complementary medicine principles, with the standard recommended Dietary Approach to Stop Hypertension (DASH). A total of 113 patients treated with antihypertensive drugs were randomly assigned to either CALM-BP treatment (consisting of rice diet, walks, yoga, relaxation and stress management) or to a DASH+exercise control group (consisting of DASH and walks). Ambulatory 24-h and home BP were monitored over a 16-week programme, followed by 6 months of maintenance period. Medications were reduced if systolic BP dropped below 110 mm Hg accompanied by symptoms. In addition to BP reduction, medications were reduced because of symptomatic hypotension in 70.7% of the CALM-BP group compared with 32.7% in the DASH group, P<0.0001. After 6 months, medication status was not altered in the majority of individuals. Significant reductions in body mass index, cholesterol and improved quality-of-life scores were observed only in the CALM-BP group. Lifestyle and diet modifications based on complementary medicine principles are highly effective with respect to BP control, medication use and cardiovascular risk factors.

A 90-day subchronic toxicity study and reproductive toxicity studies on ACE-inhibiting lactotripeptide.

In recent years there has been an increasing body of literature describing the antihypertensive effects of peptides produced from milk protein. The tripeptides isoleucine-proline-proline (IPP) and valine-proline-proline (VPP), isolated from hydrolysed casein have been shown to lower blood pressure by inhibiting angiotensin I-converting enzyme (ACE). This has led to the use of these tripeptides, collectively referred to as lactotripeptide (LTP) as ingredients of functional foods intended to help control blood pressure. A programme of studies including a 90-day repeat-dose oral gavage toxicity study in the rat and an embryo-fetal (pre-natal) development study in the rabbit was conducted to ensure the safety of this ACE-inhibiting ingredient. In addition, a non-standard pre- and post-natal development study in the rat was performed. This study included direct dosing of the neonates, and was designed specifically to investigate renal development and to ensure that the bioactive peptides were not associated with the same type of fetopathy exhibited by ACE inhibiting drugs. These studies showed that there were no adverse effects of treatment at the highest doses tested.

Expression of the conjugate export pump encoded by the mrp2 gene in the apical membrane of kidney proximal tubules.

A novel ATP-dependent export pump for amphiphilic anionic conjugates, which has been cloned recently from liver, was identified in rat kidney and localized to the apical membrane domain of proximal tubule epithelia. This 190-kD membrane glycoprotein (Mrp2) has been described previously as the hepatocyte canalicular isoform of the multidrug resistance protein and as the canalicular multispecific organic anion transporter. Mrp2 was identified in kidney by reverse transcription PCR followed by sequencing of the amplified 786-bp fragment and by immunoblotting, using an antibody specifically reacting with the carboxy terminus of rat Mrp2. Double immunofluorescence and confocal laser-scanning microscopy showed the presence of Mrp2 in the brush-border membrane domain of segments S1, S2, and S3 of proximal tubule epithelia. Mrp2 was not detectable in other segments of the nephron. The onset of Mrp2 expression during development occurred in a very early stage of nephron development. Mrp2 represents the first cloned ATP-dependent export pump for amphiphilic organic anions identified in kidney and localized to the apical membrane domain of proximal tubule epithelia. Mrp2 may contribute to cellular detoxification and to the secretion of endogenous and xenobiotic anionic substances, most of which are conjugates, from the blood into urine.

Determination of urinary glutathione S-transferase and lactate dehydrogenase for differentiation between proximal and distal nephron damage.

Cytosolic glutathione S-transferase (GST) activity is confined to the proximal convoluted and straight tubules. Damage to these parts of the nephron should result in leakage of GST into the urinary space. Lactate dehydrogenase (LDH), in contrast, is more generally distributed along the nephron. Measurement of both enzyme activities could therefore be expected to discriminate between different localizations of nephrotoxicity. To test this hypothesis, we determined both enzyme activities in 24 h urine samples from 10-12 female Sprague-Dawley rats, each treated with single i.p. injections of puromycin aminonucleoside (PAN, 130 mg/kg), Na2 CrO4 10, 20, 30 mg/kg), mercuric chloride (HgCl2, 0.5, 0.75, 1.0 mg/kg), folic acid (125, 350, 375 mg/kg), ethyleneimine (0.5, 2.0, 5.0 microliters/kg). Bovine serum albumin (BSA) was injected by the same method, twice daily on 3 consecutive days (2.5, 7.14 g/kg). The results obtained indicate a characteristic dose- and time-dependent pattern of excreted enzyme activities for each of the tested compounds. In both models with primarily glomerular damage, proximal tubular parts were also affected, as could be demonstrated by increased urinary GST and histopathological changes. Damage, mainly to the S1/S2 segment by 20 or 30 mg Na2 CrO4/kg, resulted in moderate to marked increases in LDH excretion, while GST was only moderately elevated at 30 mg/kg. Extreme increases in GST and LDH output were measured after predominant S3 segment damage after 0.75 and 1.0 mg HgCl2/kg. The distally active compounds, folic acid and ethyleneimine, did not increase GST excretion at lower doses. At the high doses, a small rise in GST excretion indicated some, probably secondary, proximal tubular involvement, which correlated with the histopathological findings in these groups.

Chronic effects on single and multiple oral and subcutaneous cadmium administrations on the testes of Wistar rats.

Thirty mature male Wistar rats were administered cadmium as CdCl2 X 1H2O in single doses of 50 mg/kg p.o. or 2.5 mg/kg i.p. or 10 weekly doses of 5 mg/kg p.o. or 0.25 mg/kg i.p., respectively. Ten males, each treated correspondingly with the vehicle, served as control groups. Some of the animals were necropsied after 12 and 18 months, respectively, the remainder were kept for up to 30 months. In a supplementary study 25 males were each treated once with 200 mg/kg p.o. or 2 mg/kg s.c. and 35 males with 100 mg/kg p.o. This experiment was terminated after 6 months. Animals having received 1 X 100 or 1 X 200 mg/kg p.o. or 1 X 2.0 or 1 X 2.5 mg/kg s.c. showed severe lesions of the whole testicular parenchyma with massive calcification of the necrotic tubuli and pronounced fibrosis of the interstitium. All animals receiving 2.5 mg/kg s.c. had a Leydig cell tumor in at least one of the testes. In 5 out of 15 animals surviving 18 months these tumors were classified as malignant (mean time of induction: 858 +/- 77 days). All the other tumors detected were not regarded as causally related to treatment. The results of the supplementary study indicate that with very high oral cadmium dosages Leydig cell tumors may be induceable. Since the massive lesion of the testes appears to be the prerequisite for the occurrence of induced Leydig cell tumors, a non-genetic mechanism is to be assumed in respect to the formation of these tumors.

Comparative investigations on the effects of acute intraperitoneal cadmium, chromium, and mercury exposure on the kidney.

Urinary excretion of lactate dehydrogenase (LDH), glutathione-S-transferase (GST), leucine arylamidase (LAS), gamma-glutamyltransferase (GGT), beta-galactosidase (GAL), beta-N-acetyl-D-glucosaminidase (NAG), sodium, and glucose were determined in female Sprague-Dawley rats the subsequent three days after intraperitoneal treatment with single doses of 4.5 mg CdCl2 X 1H2O/kg, 20 mg Na2CrO4/kg, and 0.75 mg HgCl2/kg body weight. Although the pathological effects were localized within the same part of the nephron (i.e., the proximal tubule), there were marked differences with regard to the extent and time course of the parameters affected. Treatment with cadmium resulted essentially in a marked decline in sodium and glucose excretion. The administration of chromate led to a slightly to moderately elevated excretion of the enzyme activities measured with the cytosolic LDH as the most increased enzyme (ca. 500% of controls on Day 3 postadministration). Median glucose excretion was unaffected whereas sodium excretion was transiently reduced. The maximum of enzyme excretion after HgCl2 was essentially the same on the first day postadministration and the amount of enzyme activity in urine up to 20 times higher compared to that after chromium. Sodium excretion was below that of controls on Days 2 and 3, whereas glucose excretion was markedly elevated (up to 8000% of controls). The results indicate that it is possible to discriminate with the use of selected urinary enzymes, substrates, and electrolytes various kinds of nephrotoxic actions not only in different but also within the same part of the nephron.

In vivo activity of proteases of Pseudomonas aeruginosa in a rat model.

The granuloma pouch technique was used to study the in vivo characteristics of four strains of Pseudomonas aeruginosa that differed in levels of alkaline protease and elastase production. Bacterial counts, alkaline protease and elastase concentrations, and IgG levels of pouch exudates were determined quantitatively; total protein levels were determined semiquantitatively. In vivo protease concentrations were in the nanogram range; during the investigated period individual strains either increased enzyme production or remained negative. In vitro alkaline protease:elastase ratios correlated with in vivo ratios in three of the four strains. Proteolytic strains caused a decrease in IgG and alpha 2-fraction proteins. Purified rat IgG was cleaved rapidly by elastase and slowly by alkaline protease; both cleaved IgG at the hinge region. The study determines the concentration of P aeruginosa alkaline protease and elastase after infection in a rat model, shows cleavage of rat IgG and other proteins due to alkaline protease and elastase, and suggests that enzymes other than proteases are involved in the pathogenesis of P aeruginosa infections.

Pattern formation by interaction of three cytoplasmic factors in the egg of the leafhopper Euscelis plebejus.

Developmental capacities of different parts of the Euscelis plebejus egg were tested by translocating posterior pole material and subsequent transverse constriction of the egg posterior to the translocated material. The results support the hypothesis that at least three cytoplasmic factors of maternal origin are necessary to form a complete germ band. Those factors do not act autonomously. The anterior and posterior factors require interaction with the middle factor in order to cause formation of head and abdomen, respectively. The middle factor, on the other hand, forms a complete thorax only if it is in contact with the posterior factor.

Pathomorphologic findings in short-tailed voles (Microtus agrestis) experimentally-infected with Frenkelia microti.

Following oral infection of Microtus agrestis with sporocysts of Frenkelia microti, transient focal necrosis and cellular infiltrations in the liver, hyperplasia of lymphoid organs, and inflammatory infiltrations in the heart, pulmonary veins, skeletal muscles and brain occurred during the first asexual multiplication period of the parasite in the liver. Frenkelia cysts were first observed in the brain 23 days after infection.