Soil-transmitted helminth infections in free-ranging non-human primates from Cameroon and Gabon

BACKGROUND

Zoonotic diseases are a serious threat to both public health and animal conservation. Most non-human primates (NHP) are facing the threat of forest loss and fragmentation and are increasingly living in closer spatial proximity to humans. Humans are infected with soil-transmitted helminths (STH) at a high prevalence, and bidirectional infection with NHP has been observed. The aim of this study was to determine the prevalence, genetic diversity, distribution and presence of co-infections of STH in free-ranging gorillas, chimpanzees and other NHP species, and to determine the potential role of these NHP as reservoir hosts contributing to the environmental sustenance of zoonotic nematode infections in forested areas of Cameroon and Gabon.

METHODS

A total of 315 faecal samples from six species of NHPs were analysed. We performed PCR amplification, sequencing and maximum likelihood analysis of DNA fragments of the internal transcribed spacer 2 (ITS2) nuclear ribosomal DNA to detect the presence and determine the genetic diversity of Oesophagostomum spp., Necator spp. and Trichuris spp., and of targeted DNA fragments of the internal transcribed spacer 1 (ITS1) to detect the presence of Ascaris spp.

RESULTS

Necator spp. infections were most common in gorillas (35 of 65 individuals), but also present in chimpanzees (100 of 222 individuals) and in one of four samples from greater spot-nosed monkeys. These clustered with previously described type II and III Necator spp. Gorillas were also the most infected NHP with Oesophagostomum (51/65 individuals), followed by chimpanzees (157/222 individuals), mandrills (8/12 samples) and mangabeys (7/12 samples), with O. stephanostomum being the most prevalent species. Oesophagostomum bifurcum was detected in chimpanzees and a red-capped mangabey, and a non-classified Oesophagostomum species was detected in a mandrill and a red-capped mangabey. In addition, Ternidens deminutus was detected in samples from one chimpanzee and three greater spot-nosed monkeys. A significant relative overabundance of co-infections with Necator and Oesophagostomum was observed in chimpanzees and gorillas. Trichuris sp. was detected at low prevalence in a gorilla, a chimpanzee and a greater spot-nosed monkey. No Ascaris was observed in any of the samples analysed.

CONCLUSIONS

Our results on STH prevalence and genetic diversity in NHP from Cameroon and Gabon corroborate those obtained from other wild NHP populations in other African countries. Future research should focus on better identifying, at a molecular level, the species of Necator and Oesophagostomum infecting NHP and determining how human populations may be affected by increased proximity resulting from encroachment into sylvatic STH reservoir habitats.

MicroRNA-127-3p controls murine hematopoietic stem cell maintenance by limiting differentiation

The balance between self-renewal and differentiation is crucial to ensure the homeostasis of the hematopoietic system, and is a hallmark of hematopoietic stem cells. However, the underlying molecular pathways, including the role of micro-RNA, are not completely understood. To assess the contribution of micro-RNA, we performed micro-RNA profiling of hematopoietic stem cells and their immediate downstream progeny multi-potent progenitors from wild-type control and Pbx1-conditional knockout mice, whose stem cells display a profound self-renewal defect. Unsupervised hierarchical cluster analysis separated stem cells from multi-potent progenitors, suggesting that micro-RNA might regulate the first transition step in the adult hematopoietic development. Notably, Pbx1-deficient and wild-type cells clustered separately, linking micro-RNAs to self-renewal impairment. Differential expression analysis of micro-RNA in the physiological stem cell-to-multi-potent progenitor transition and in Pbx1-deficient stem cells compared to control stem cells revealed miR-127-3p as the most differentially expressed. Furthermore, miR-127-3p was strongly stem cell-specific, being quickly down-regulated upon differentiation and not re-expressed further downstream in the bone marrow hematopoietic hierarchy. Inhibition of miR-127-3p function in Lineage-negative cells, achieved through a lentiviral-sponge vector, led to severe stem cell depletion, as assessed with serial transplantation assays. miR-127-3p-sponged stem cells displayed accelerated differentiation, which was uncoupled from proliferation, accounting for the observed stem cell reduction. miR-127-3p overexpression in Lineage-negative cells did not alter stem cell pool size, but gave rise to lymphopenia, likely due to lack of miR-127-3p physiological downregulation beyond the stem cell stage. Thus, tight regulation of miR-127-3p is crucial to preserve the self-renewing stem cell pool and homeostasis of the hematopoietic system.

Use of RNAlater as a preservation method for parasitic coprology studies in wild-living chimpanzees

We evaluated the use of an RNA stabilisation buffer, RNAlater (Ambion, Austin, Texas), as a preservation medium for parasitic coprology analysis of faecal samples collected from chimpanzees living in the wild (Pan troglodytes troglodytes). Thirty faecal samples collected in the forests of south-east Cameroon (Mambele area) from 2003 to 2011 were preserved in RNAlater at -80 °C and analysed for their parasite content. We identified and counted parasitic elements and assessed their shape, size and morphology in relation to the storage time of the samples. We found that parasite elements were identifiable in RNAlater preserved samples after as many as 7 years, showing that RNAlater could be an effective and reliable preservation medium for coprology. Thus, its use could be an interesting way to optimise sample collection for several types of studies (parasitology and bacteriology/virology) at once, especially considering the logistically challenging and time-consuming field campaigns needed to obtain these faecal samples.

Enzymatic production of biodiesel from cotton seed oil using t-butanol as a solvent

The enzymatic production of biodiesel by methanolysis of cottonseed oil was studied using immobilized Candida antarctica lipase as catalyst in t-butanol solvent. Methyl ester production and triacylglycerol disappearance were followed by HPLC chromatography. It was found, using a batch system, that enzyme inhibition caused by undissolved methanol was eliminated by adding t-butanol to the reaction medium, which also gave a noticeable increase of reaction rate and ester yield. The effect of t-butanol, methanol concentration and temperature on this system was determined. A methanolysis yield of 97% was observed after 24h at 50 degrees C with a reaction mixture containing 32.5% t-butanol, 13.5% methanol, 54% oil and 0.017 g enzyme (g oil)(-1). With the same mixture, a 95% ester yield was obtained using a one step fixed bed continuous reactor with a flow rate of 9.6 mlh(-1) (g enzyme)(-1). Experiments with the continuous reactor over 500 h did not show any appreciable decrease in ester yields.

24S-hydroxycholesterol in cerebrospinal fluid is elevated in early stages of dementia

The brain is the most cholesterol-rich organ in the human body. Accumulation of excess cholesterol in hippocampal neurons promotes the cleavage of the amyloid precursor protein (APP) into amyloidogenic components with the consequence of the acceleration of neuronal degeneration. Conversion of cholesterol to 24S-hydroxycholesterol mediated by cholesterol 24S-hydroxylase (CYP46) is the major pathway for the elimination of brain cholesterol and the maintenance of brain cholesterol homeostasis. We examined whether cerebrospinal fluid (CSF) 24S-hydroxycholesterol levels differ between patients with dementia, patients with mild cognitive impairment (MCI), and cognitively intact control subjects. Plasma and CSF concentrations of 24S-hydroxycholesterol and cholesterol in 32 patients with Alzheimer's disease (AD), 11 patients with vascular dementia, seven patients with MCI, and seven cognitively intact control subjects were measured by combined gas-chromatography/mass spectrometry. We show elevated concentrations of 24S-hydroxycholesterol in the CSF of AD patients and we interpret this finding as a consequence of increased cholesterol turnover in the central nervous system during neurodegeneration. The observed influence of the apolipoprotein E epsilon4 (APOE4) allele on CSF 24S-hydroxycholesterol concentrations with a gene-dosage effect suggests the existence of a link between the AD risk factor APOE4 and CNS cholesterol metabolism. The elevation of CSF 24S-hydroxycholesterol appears to occur early in the disease process, since patients with mild cognitive impairment had also increased CSF concentrations of this compound. We believe that the CSF concentration of 24S-hydroxycholesterol is altered in AD-related neurodegeneration and thus, CSF 24S-hydroxycholesterol may be a marker for monitoring the onset and progression of the disease.

Cholesterol dynamics in the foetal and neonatal brain as reflected by circulatory levels of 24S-hydroxycholesterol

Oxysterols, particularly those hydroxylated in the steroid side-chain, are formed from cholesterol by specific cytochrome P450 enzymes and may facilitate elimination of cholesterol from extrahepatic sources. In humans, the greatest portion of circulating 24S-hydroxycholesterol (24S-OH-Chol) is derived from the brain and the absolute concentration depends on age. In the present study, concentrations of 24S-OH-Chol and for comparison 27-OH-Chol were determined by a highly sensitive isotope dilution method using gas chromatography-mass spectrometry in serum samples from normal preterm and term neonates and those with Rhesus haemolytic disease, taken serially for diagnostic purposes. Serum concentrations of cholesterol, 24S-OH-Chol and 27-OH-Chol were similar in venous versus arterial cord blood of 6 term neonates. Serum concentrations of 24S-OH-Chol and 27-OH-Chol in 12 small for gestational age (SGA) preterm neonates were significantly lower than those in 12 appropriate for gestational age (AGA) preterm neonates (p < 0.001), and also lower than those in 12 SGA (0 < 0.001) and 12 AGA term neonates (p < 0.05). Serum cholesterol was significantly higher in preterm than in term neonates (p < 0.001). 24S-OH-Chol serially determined in 8 infants with Rhesus haemolytic disease increased 5-6-fold during the first 3 mo after birth (from 42 +/- 20 ng ml(-1) to 227 +/- 71 ng ml(-1)). 27-OH-Chol increased simultaneously from 30 +/- 14 ng ml(-1) to 100 +/- 39 ng ml(-1).

CONCLUSION

Serum concentrations of 24S-OH-Chol increased 5-6-fold after birth. This could be an indication of normal cholesterol metabolism in the developing neonatal brain.

The maize WD-repeat gene ZmRbAp1 encodes a member of the MSI/RbAp sub-family and is differentially expressed during endosperm development

Members of the MSI/RbAp sub-family of WD-repeat proteins are widespread in eukaryotic organisms and form part of multiprotein complexes that are involved in various biological pathways, including chromatin assembly, regulation of gene transcription, and cell division. In this study we report the isolation and characterization of a cDNA sequence from Zea mays, which encodes an RbAp-like protein (ZmRbAp1) that binds acetylated histones H3 and H4 and suppresses mutations that have a negative effect on the Ras/cAMP pathway in yeast. The ZmRbAp genes form a gene family and are expressed in different tissues of Z. mays L. plants. Determination of its expression pattern during maize seed development revealed that ZmRbAp transcripts are abundant during the initial stages of endosperm formation. In addition, the transcripts are specifically localized in shoot apical meristem and leaf primordia of the embryo. A possible role for the ZmRbAp genes in early endosperm differentiation and plant development is discussed.

Plasma 24S-hydroxycholesterol: a peripheral indicator of neuronal degeneration and potential state marker for Alzheimer's disease

The conversion of brain cholesterol into 24S-hydroxycholesterol and its subsequent release into the periphery is probably an important step for the maintenance of brain cholesterol homeostasis. Recent findings suggest that plasma 24S-hydroxycholesterol may be elevated in Alzheimer's disease (AD) and vascular dementia at least at some stage of the disease, suggesting increased brain cholesterol turnover during neurodegeneration. We investigated whether plasma 24S-hydroxycholesterol concentrations depend on the severity of AD and on the apolipoprotein E (apoE) genotype. Severity of AD and inheritance of the apoE4 allele were independently associated with reduced plasma 24S-hydroxycholesterol/cholesterol ratios. The results suggest that the decrease of plasma 24S-hydroxycholesterol/cholesterol in severely affected AD patients is a peripheral marker for loss of cholesterol 24S-hydroxylase in the CNS. Inheritance of the apoE4 allele may be associated with increased apoE-mediated transport of brain cholesterol to the periphery or with decreased activity of the 24S-hydroxylase. Longitudinal studies will assess the validity of the ratio plasma 24S-hydroxycholesterol/cholesterol as a state marker for AD.

Plasma 24S-hydroxycholesterol (cerebrosterol) is increased in Alzheimer and vascular demented patients

Alzheimer's disease (AD) is characterized by the presence of senile plaques, neurofibrillary tangles, and neuronal cell loss associated with membrane cholesterol release. 24S-hydroxycholesterol (24S-OH-Chol) is an enzymatically oxidized product of cholesterol mainly synthesized in the brain. We tested the hypothesis that plasma levels of this oxysterol could be used as a putative biochemical marker for an altered cholesterol homeostasis in the brain of AD patients. Thirty patients with clinical criteria for AD, 30 healthy volunteers, 18 depressed patients, and 12 patients with vascular dementia (non-Alzheimer demented) were studied. Plasma concentrations of 24S-OH-Chol were assayed by isotope dilution;-mass spectrometry, cholesterol was measured enzymatically, and apolipoprotein E (apoE) was genotyped by polymerase chain reaction and restricted fragment length polymorphism. The concentration of 24S-OH-Chol in AD and non-Alzheimer demented patients was modestly but significantly higher than in healthy controls and in depressed patients. There was no significant difference in the concentrations of 24S-OH-Chol between depressed patients and healthy controls nor between AD and non-Alzheimer demented patients. The apoE straightepsilon4 allele influences plasma 24S-OH-Chol. However, this influence could be completely accounted for by the elevated plasma cholesterol in apoE4 hetero- or homozygotes. Plasma 24S-OH-Chol levels correlated negatively with the severity of dementia. AD and vascular demented patients appear to have higher circulating levels of 24S-OH-Chol than depressed patients and healthy controls. We speculate that 24S-OH-Chol plasma levels may potentially be used as an early biochemical marker for an altered cholesterol homeostasis in the central nervous system. 24S-hydroxycholesterol (cerebrosterol) is increased in Alzheimer and vascular demented patients.

Cutting edge: apoptosis of superantigen-activated T cells occurs preferentially after a discrete number of cell divisions in vivo

Staphylococcal enterotoxins are bacterial products that display superantigen activity in vitro as well as in vivo. For instance, staphylococcal enterotoxin B (SEB) polyclonally activates T cells that bear the Vbeta8 gene segment of the TCR. SEB-activated T cells undergo a burst of proliferation that is followed by apoptosis. Using an in vivo adaptation of a fluorescent cell division monitoring technique, we show here that SEB-activated T cells divide asynchronously, and that apoptosis of superantigen-activated T cells is preferentially restricted to cells which have undergone a discrete number of cell divisions. Collectively, our data suggest that superantigen-activated T cells are programmed to undergo a fixed number of cell divisions before undergoing apoptosis. A delayed death program may provide a mechanistic compromise between effector functions and homeostasis of activated T cells.

Evaluation of hypothalamic dopaminergic function by neuropharmacologic means in aged women

The function of the hypothalamic tuberoinfundibular dopaminergic (TIDA) neurons involved in the control of prolactin secretion was investigated in aged subjects with the use of nomifensine, an indirect-acting dopamine (DA) agonist, domperidone, a DA receptor antagonist, and DA, which acts directly on the pituitary lactotropes. In all 33 women, aged 69-92 yr, were studied. Baseline prolactin values were slightly but significantly higher in aged women (13 +/- 1.2 ng/ml, M +/- S.E.M.) than in a group of control fertile women (8 +/- 0.7 ng/ml). Oral administration of nomifensine (200 mg), in 14 aged women suppressed plasma prolactin (greater than or equal to 30% of baseline) in 8 subjects, a proportion not different from that present in fertile women (7/15) also receiving a single oral dose of nomifensine. Intravenous infusion of DA (0.04 microgram/kg min, 120 min) induced a similar inhibition in plasma prolactin in the aged and the fertile women, while administration of domperidone (4 mg i.v.) evoked a higher plasma prolactin rise, 15 min post-administration, in fertile than aged women. In all, presence of baseline prolactin levels only slightly elevated and prolactin responsiveness to nomifensine and DA not different from that of fertile women denote preservation of TIDA neuronal function in old women. The blunted response to domperidone of the old women is likely attibutable to a reduced pituitary pool of prolactin.

Tubero-infundibular dopaminergic function in cirrhotic patients: evaluation by nomifensine and domperidone

Cirrhotic patients reportedly show alterations of anterior pituitary hormone secretion, which may reflect an underlying defective central neurotransmitter function. In this study, we have investigated the catecholaminergic control of prolactin (Prl) and growth hormone (GH) secretion in cirrhotic patients by means of an indirectly acting dopamine (DA) and norepinephrine agonist, nomifensine (Nom), and a DA receptor antagonist, domperidone (Dom). Basal GH levels were higher in the 12 female and male cirrhotic patients than in the 12 age- and sex-matched normal controls, while no difference was present in basal Prl values. Administration of Nom (200 mg po) suppressed basal Prl levels (at least 30% inhibition at three consecutive times post-drug administration) in 6/12 controls and in 6/12 cirrhotic patients, the frequency of negative responses not being different between the two groups. Nom induced a slight elevation of GH levels in controls, and evoked a more marked and sustained GH increase in cirrhotic patients. Administration of Dom (4 mg iv) induced similar Prl increments in 6 male controls and 6 male cirrhotic patients. Normal Prl responsiveness to Nom and Dom points to the existence of preserved tubero-infundibular DA function and modulation of pituitary DA receptors in the cirrhotic patients investigated. Higher GH responsiveness to Nom is compatible with a different bioavailability of the drug.