Dehydroepiandrosterone (DHEA) treatment in vitro inhibits adipogenesis in human omental but not subcutaneous adipose tissue

Dehydroepiandrosterone (DHEA), a precursor sex steroid, circulates in sulphated form (DHEAS). Serum DHEAS concentrations are inversely correlated with metabolic syndrome components and in vivo/in vitro studies suggest a role in modulating adipose mass. To investigate further, we assessed the in vitro biological effect of DHEA in white (3T3-L1) and brown (PAZ6) preadipocyte cell lines and human primary preadipocytes. DHEA (from 10(-8)M) caused concentration-dependent proliferation inhibition of 3T3-L1 and PAZ6 preadipocytes. Cell cycle analysis demonstrated unaltered apoptosis but indicated blockade at G1/S or G2/M in 3T3-L1 and PAZ6, respectively. Preadipocyte cell-line adipogenesis was not affected. In human primary subcutaneous and omental preadipocytes, DHEA significantly inhibited proliferation from 10(-8)M. DHEA 10(-7)M had opposing effects on adipogenesis in the two fat depots. Subcutaneous preadipocyte differentiation was unaffected or increased whereas omental preadipocytes showed significantly reduced adipogenesis. We conclude that DHEA exerts fat depot-specific differences which modulate body composition by limiting omental fat production.

Genotyping of Trypanosoma cruzi: systematic selection of assays allowing rapid and accurate discrimination of all known lineages

Trypanosoma cruzi, the agent of Chagas disease, can be subdivided into six discrete typing units (DTUs), TcI, TcIIa, TcIIb, TcIIc, TcIId or TcIIe, each having distinct epidemiologically important features. Dozens of genetic markers are available to determine the DTU to which a T. cruzi isolate belongs, but there is no consensus on which should be used. We selected five assays: three polymerase chain reaction (PCR)-restriction fragment length polymorphisms based on single nucleotide polymorphisms (SNPs) in the HSP60, Histone H1, and GPI loci, and PCR product size polymorphism of the LSU rDNA and mini-exon loci. Each assay was tested for its capacity to differentiate between DTUs using a panel of 48 genetically diverse T. cruzi clones. Some markers allowed unequivocal identification of individual DTUs, however, only by using a combination of multiple markers could all six DTUs be resolved. Based upon the results we recommend a triple-assay comprising the LSU rDNA, HSP60 and GPI markers for reliable, rapid, low-cost DTU assignment.

Flow cytometric analysis and microsatellite genotyping reveal extensive DNA content variation in Trypanosoma cruzi populations and expose contrasts between natural and experimental hybrids

Trypanosoma cruzi exhibits remarkable genetic heterogeneity. This is evident at the nucleotide level but also structurally, in the form of karyotypic variation and DNA content differences between strains. Although natural populations of T. cruzi are predominantly clonal, hybrid lineages (TcIId and TcIIe) have been identified and hybridisation has been demonstrated in vitro, raising the possibility that genetic exchange may continue to shape the evolution of this pathogen. The mechanism of genetic exchange identified in the laboratory is unusual, apparently involving fusion of diploid parents followed by genome erosion. We investigated DNA content diversity in natural populations of T. cruzi in the context of its genetic subdivisions by using flow cytometric analysis and multilocus microsatellite genotyping to determine the relative DNA content and estimate the ploidy of 54 cloned isolates. The maximum difference observed was 47.5% between strain Tu18 cl2 (TcIIb) and strain C8 cl1 (TcI), which we estimated to be equivalent to ∼73 Mb of DNA. Large DNA content differences were identified within and between discrete typing units (DTUs). In particular, the mean DNA content of TcI strains was significantly less than that for TcII strains (P < 0.001). Comparisons of hybrid DTUs TcIId/IIe with corresponding parental DTUs TcIIb/IIc indicated that natural hybrids are predominantly diploid. We also measured the relative DNA content of six in vitro-generated TcI hybrid clones and their parents. In contrast to TcIId/IIe hybrid strains these experimental hybrids comprised populations of sub-tetraploid organisms with mean DNA contents 1.65–1.72 times higher than the parental organisms. The DNA contents of both parents and hybrids were shown to be relatively stable after passage through a mammalian host, heat shock or nutritional stress. The results are discussed in the context of hybridisation mechanisms in both natural and in vitro settings.

Genome-scale multilocus microsatellite typing of Trypanosoma cruzi discrete typing unit I reveals phylogeographic structure and specific genotypes linked to human infection

Trypanosoma cruzi is the most important parasitic infection in Latin America and is also genetically highly diverse, with at least six discrete typing units (DTUs) reported: Tc I, IIa, IIb, IIc, IId, and IIe. However, the current six-genotype classification is likely to be a poor reflection of the total genetic diversity present in this undeniably ancient parasite. To determine whether epidemiologically important information is "hidden" at the sub-DTU level, we developed a 48-marker panel of polymorphic microsatellite loci to investigate population structure among 135 samples from across the geographic distribution of TcI. This DTU is the major cause of resurgent human disease in northern South America but also occurs in silvatic triatomine vectors and mammalian reservoir hosts throughout the continent. Based on a total dataset of 12,329 alleles, we demonstrate that silvatic TcI populations are extraordinarily genetically diverse, show spatial structuring on a continental scale, and have undergone recent biogeographic expansion into the southern United States of America. Conversely, the majority of human strains sampled are restricted to two distinct groups characterised by a considerable reduction in genetic diversity with respect to isolates from silvatic sources. In Venezuela, most human isolates showed little identity with known local silvatic strains, despite frequent invasion of the domestic setting by infected adult vectors. Multilocus linkage indices indicate predominantly clonal parasite propagation among all populations. However, excess homozygosity among silvatic strains and raised heterozygosity among domestic populations suggest that some level of genetic recombination cannot be ruled out. The epidemiological significance of these findings is discussed.

The importance of militaries from developing countries in global infectious disease surveillance

Military forces from developing countries have become increasingly important as facilitators of their government's foreign policy, taking part in peacekeeping operations, military exercises and humanitarian relief missions. Deployment of these forces presents both challenges and opportunities for infectious disease surveillance and control. Troop movements may cause or extend epidemics by introducing novel agents to susceptible populations. Conversely, military units with disease surveillance and response capabilities can extend those capabilities to civilian populations not served by civilian public health programmes, such as those in remote or post-disaster settings. In Peru and Thailand, military health organizations in partnership with the military of the United States use their laboratory, epidemiological, communications and logistical resources to support civilian ministry of health efforts. As their role in international affairs expands, surveillance capabilities of militaries from developing countries should be enhanced, perhaps through partnerships with militaries from high-income countries. Military-to-military and military-to-civilian partnerships, with the support of national and international civilian health organizations, could also greatly strengthen global infectious disease surveillance, particularly in remote and post-disaster areas where military forces are present.

The importance of militaries from developing countries in global infectious disease surveillance

Military forces from developing countries have become increasingly important as facilitators of their government's foreign policy, taking part in peacekeeping operations, military exercises and humanitarian relief missions. Deployment of these forces presents both challenges and opportunities for infectious disease surveillance and control. Troop movements may cause or extend epidemics by introducing novel agents to susceptible populations. Conversely, military units with disease surveillance and response capabilities can extend those capabilities to civilian populations not served by civilian public health programmes, such as those in remote or post-disaster settings. In Peru and Thailand, military health organizations in partnership with the military of the United States use their laboratory, epidemiological, communications and logistical resources to support civilian ministry of health efforts. As their role in international affairs expands, surveillance capabilities of militaries from developing countries should be enhanced, perhaps through partnerships with militaries from high-income countries. Military-to-military and military-to-civilian partnerships, with the support of national and international civilian health organizations, could also greatly strengthen global infectious disease surveillance, particularly in remote and post-disaster areas where military forces are present.

Resolution of multiclonal infections of Trypanosoma cruzi from naturally infected triatomine bugs and from experimentally infected mice by direct plating on a sensitive solid medium

The isolation of biological clones of Trypanosoma cruzi by microscopically dispensing individual organisms or by serial dilution is laborious and time consuming. The inability to resolve mixed T. cruzi infections, from vectors and hosts, and to isolate clones of slow growing genotypes by efficient plating on solid media, has hindered characterisation studies and downstream applications. We have devised and validated a sensitive, solid medium plating technique for rapid in vitro isolation of clones representative of all the recognised T. cruzi lineages (TCI, TCIIa-e), including the slow growing strain CANIII (TC IIa) and Trypanosoma rangeli, with high plating efficiencies. Furthermore, the method is effective for the isolation of clones directly from silvatic triatomine bugs and from experimentally infected mice harbouring mixed infections, allowing resolution of multiclonal infections from varied sources.

Who put the self in self-organization? A clarification of terms and concepts for developmental psychopathology

The term self-organization has at least two meanings for developmental psychopathologists: the spontaneous emergence of order in developing systems and the consolidation of that part of the person called the self. The first meaning is shared across the sciences at large, and it denotes a general model of change and growth in complex systems. We review principles of self-organization from the natural sciences and discuss their application to the study of human development. We then suggest possible sources and consequences of terminological confusion in developmental psychology and offer some potential resolutions. The "self" in self-organization seems a special case of this confusion, and it can be addressed by modeling the self as both autonomous agent and emergent form. We outline preliminary directions for this modeling and then go on to a more general discussion of how principles of self-organization can help bring developmental psychopathology closer to its goals.

Establishment of a non-human primate Campylobacter disease model for the pre-clinical evaluation of Campylobacter vaccine formulations

Campylobacter jejuni is a common cause of enteritis worldwide. The mechanisms by which C. jejuni causes disease are unclear. Challenge studies in humans are currently considered unethical due to the possibility of severe complications, such as Guillain-Barré syndrome. Campylobacter infection in non-human primates closely mimics the disease and immune response, seen in humans. In this study, we attempted to determine the minimal dose of a pathogenic C. jejuni 81-176 strain required for clinical signs and symptoms of disease (> or = 80% attack rate) in Macaca mulatta monkeys using an escalating dosage (three doses for three monkey groups: 10(7), 10(9) and 10(11) cfu). Eighty percent of the monkeys challenged with highest dose (10(11) cfu) had mild disease, but the 80% attack rate (moderate diarrhea in 80% of the monkeys) was not achieved. However, 100% of monkeys showed IgA seroconversions (three-fold over pre-challenge titers). The elicited immune response was challenge dose-dependent. Campylobacter antigen specific fecal s-IgA responses were observed in all challenged groups but the response was not dose-dependent. Only IgM antibody secreting cells response was observed against Campylobacter antigens. The elicited immune response in three groups of rhesus monkeys was dose-dependent, indicating this monkey model can be used for pre-clinical evaluation of Campylobacter candidate vaccines, however these adult rhesus monkeys are less prone to Campylobacter infection.

Typhoid Fever: A Massive, Single-Point Source, Multidrug-Resistant Outbreak in Nepal

BACKGROUND

In the summer of 2002, a total of 5963 cases of typhoid fever were recorded in Bharatpur, Nepal (population, 92,214) during a 7-week period. A team from the Armed Forces Research Institute of Medical Sciences in Bangkok, Thailand, and the CIWEC Travel Medicine Clinic (Kathmandu, Nepal) assisted the Nepal National Public Health Laboratory (Kathmandu, Nepal) in the further investigation of this large, explosive febrile disease outbreak.

METHODS

Investigators conducted a thorough epidemiologic and laboratory investigation to assess the size and scope of the outbreak. In addition to subculturing of previously collected samples, blood samples were obtained from 100 febrile patients, and culture and susceptibility testing were done by standard laboratory methods. Pulsed field gel electrophoresis (PFGE) and plasmid analysis were done.

RESULTS

The majority of the isolates, including 1 from the municipal water supply, were multidrug resistant. The minimum inhibitory concentrations (MICs) of ciprofloxacin ranged from 0.19 microg/mL to 0.125 microg/mL. With use of PFGE, all isolates, including isolates from the water supply, showed an analytical similarity of 96%-100%. Multidrug-resistant isolates had a plasmid encoding for resistance, and those with resistance to nalidixic acid had a single-point mutation.

CONCLUSIONS

To the best of our knowledge, this outbreak is the largest single-point source outbreak of multidrug-resistant typhoid fever yet reported, and it was molecularly traced to the city's single municipal water supply. Isolates were uniformly resistant to nalidixic acid, there was a decrease in their susceptibility as measured by MIC of fluoroquinolones, and 90% of isolates obtained were resistant to >1 antibiotic.

Biological activity of activating thyrotrophin receptor mutants: modulation by iodide

Epidemiological studies have revealed a significantly higher incidence of toxic adenoma (TA) and toxic multi-nodular goitre (TMNG) in regions of iodine deficiency. Fifty to eighty percent of TA and TMNG are caused by activation of the cAMP pathway, mostly by mutations in the thyrotrophin receptor (TSHR). We aimed to investigate whether iodide could modulate the biological effects of activating TSHR mutations. We have applied an in vitro model of TA comprising FRTL-5 cells stably expressing activating TSHR. We have mimicked the in vivo situation by examining the effects of prolonged exposure to iodide on the proliferation and signal transduction etc. of these cells. We observed an iodide-induced 'inhibition of proliferation' which was significant from 10 mM in the presence of serum but from 1 mM in its absence. The inhibition of proliferation was significantly higher in the activating mutant expressing FRTL-5 compared with control Neo or wild-type TSHR, indicating that the effect was mediated via the cAMP cascade. The effect was neither due to hyper-tonicity nor was it the result of an increase in cell death either by apoptosis or necrosis. Prolonged exposure to iodide produces an increase in cells in the G2 and post-G2 phases, indicating that G2/M blockade contributes to the mechanism of inhibition. The mutant expressing FRTL-5 cells have increased proliferation when chronically exposed to TSH, and this is associated with a reduction in phosphorylated (p) CREB levels. This contrasts with the effect of iodide in which inhibition of proliferation is accompanied by an increase in pCREB. In conclusion, our studies indicate that the biological effects of activating TSHR mutations vary with the ambient iodide supply and could be masked in regions of high iodine intake.

Scrub typhus reemergence in the Maldives

In summer 2002, an outbreak of febrile illness began in the Maldives in the Indian Ocean. Through April 2003, officials recorded 168 cases with 10 deaths. The Armed Forces Research Institute of Medicine in Bangkok confirmed Orientia tsutsugamushi and conducted a joint investigation with the Ministry of Health, Maldives. These cases of scrub typhus were the first in the Maldives since World War II.

Biological activity of activating thyroid-stimulating hormone receptor mutants depends on the cellular context

Activating TSH receptor (TSHR) mutations are a major cause of toxic thyroid adenoma and familial hyperthyroidism, and more than 37 such mutations have been described. Previously their functional activity had been assessed in terms of cAMP and inositol phosphate production and predominantly in transiently transfected COS-7 (monkey embryonic kidney cells), a model that does not reflect effects on thyrocyte proliferation and function. Here we have performed a systematic comparison of wild-type and seven gain-of-function TSHR mutants, introduced into rat FRTL-5 and human thyrocytes, using retroviral vectors. Our results show that 1) biological potency of TSHR mutants in thyroid cells does not correlate with their cAMP levels in transfected COS cells, highlighting the importance of cellular context and level of expression when assessing biological effects of oncogenic mutations; 2) dissociation between stimulation of function and growth occurs with thyrocyte differentiated functions more readily stimulated than growth; 3) TSHR mutants show a similar order of potency in FRTL-5 cells and human thyrocytes; 4) mutants inducing the highest stimulation of adenylyl cyclase may paradoxically fail to induce proliferation; and 5) biological effects of cAMP activating TSHR mutants are attenuated by complex counterregulatory mechanisms at least at the level of phosphodiesterases and cAMP regulatory element modulator isoforms.

Disease outbreak detection system using syndromic data in the greater Washington DC area

BACKGROUND

Many infectious disease outbreaks, including those caused by intentional attacks, may first present insidiously as ill-defined syndromes or unexplained deaths. While there is no substitute for the astute healthcare provider or laboratorian alerting the health department of unusual patient presentations, suspicious patterns may be apparent at the community level well before patient-level data raise an alarm.

METHODS

Through centralized Department of Defense medical information systems, diagnoses based on International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes are obtained daily from 99 military emergency rooms and primary care clinics across the Washington, DC, region. Similar codes are grouped together in seven diagnostic clusters that represent related presenting signs, symptoms, and diagnoses. Daily monitoring of the data is conducted and evaluated for variation from comparable historic patterns for all seven syndrome groups. Geospatial mapping and trend analysis are performed using geographic information systems software. Data were received on a daily basis beginning in December 1999 and collection continues. The data cut-off date for this manuscript was January 2002.

RESULTS

Demographic breakdown of military beneficiaries covered by the surveillance area reveals a broad age, gender, and geographic distribution that is generalizable to the Washington DC region. Ongoing surveillance for the previous 2 years demonstrates expected fluctuations for day-of-the-week and seasonal variations. Detection of several natural disease outbreaks are discussed as well as an analysis of retrospective data from the Centers for Disease Control and Prevention's sentinel physicians-surveillance network during the influenza season that revealed a significantly similar curve to the percentage of patients coded with a respiratory illness in this new surveillance system.

DISCUSSION

We believe that this surveillance system can provide early detection of disease outbreaks such as influenza and possibly intentional acts. Early detection should enable officials to quickly focus limited public health resources, decrease subsequent mortality, and improve risk communication. The system is simple, flexible, and, perhaps most critical, acceptable to providers in that it puts no additional requirements on them.

Antitumor activity of ER-51785, a new peptidomimetic inhibitor of farnesyl transferase: synergistic effect in combination with paclitaxel

Inhibitors of ras farnesylation have been extensively studied in the preclinical stage, and some of them are being developed in the clinic. Herein, we describe the antitumor activity of a new farnesyl transferase inhibitor, ER-51785. In vitro, ER-51785 selectively inhibited farnesyl transferase activity (IC50 = 77 nM) compared with geranylgeranyl transferase I activity (IC50 = 4200 nM). In cells, ER-51785 inhibited posttranslational processing of H-ras with IC50 = 28 nM, but not that of rap 1A at concentrations up to 50 microM. This compound also strongly inhibited colony formation of H-ras-transformed NIH 3T3 fibroblasts and EJ-1 bladder carcinoma cells. In vivo, ER-51785 showed potent tumor regression activity against EJ-1 xenografts but only modest activity against MIA PaCa-2 xenografts. Treatment of ER-51785 in combination with paclitaxel exhibited synergistic effects against colony formation and tumor growth of MIA PaCa-2 cells. The results presented herein support the idea that farnesyl transferase inhibitors alone and in combination with other chemotherapeutic agents have the potential to be developed as therapies for tumors expressing H-ras or K-ras oncogenes.

Adenosine-regulated cell proliferation in pituitary folliculostellate and endocrine cells: differential roles for the A(1) and A(2B) adenosine receptors

A(1) and A(2) adenosine receptors have been identified in the pituitary gland, but the cell type(s) on which they are located and their effects on pituitary cell growth are not known. Therefore, we analyzed the expression of A(1) and A(2) receptors in primary rat anterior pituitary cells, two pituitary folliculostellate (TtT/GF and Tpit/F1) and two pituitary endocrine (GH(3) and AtT20) cell lines, and compared their effects on cell proliferation. In anterior pituitary and folliculostellate cells, adenosine and adenosine receptor agonists (5'-N-ethylcarboxamidoadenosine, a universal agonist, and CGS 21680, an A(2A) receptor agonist) stimulated cAMP levels with a rank order of potency that indicates the presence of functional A(2B) receptors. This stimulation, however, was not observed in either GH(3) or AtT20 cells, where adenosine and the A(1) receptor agonist 2-chloro-N(6)-cyclopentyladenosine inhibited VIP/forskolin-stimulated cAMP production. Expression of A(2B) and A(1) receptors in the folliculostellate cells and that of the A(1) receptor in the endocrine cells were confirmed by RT-PCR, immunocytochemistry, and ligand binding. Adenosine and 5'-N-ethylcarboxamidoadenosine dose-dependently (10 nM to 10 microM) stimulated growth in the folliculostellate, but not in the endocrine, cells, whereas in the latter, 100 microM adenosine and 2-chloro-N(6)-cyclopentyladenosine inhibited cell proliferation by slowing cell cycle progression. These data highlight the differential expression of A(1) and A(2B) adenosine receptors in pituitary cells and provide evidence for opposing effects of adenosine on pituitary folliculostellate and endocrine cell growth.

Mitogen-activated protein kinase mediates epidermal growth factor-induced morphogenesis in pituitary GH3 cells

Epidermal growth factor (EGF) causes pituitary GH3 cells to change from their normal predominantly rounded morphology to much more elongated cells with extensive filopodia, and this effect is accompanied by a parallel increase in cell volume. In view of this, and because EGF receptor expression is increased in some pituitary tumours, we examined the mechanism of this EGF-induced morphological effect as it may play a role in tumour invasiveness. The effect of treatment of the cells with EGF (1 nm, 4 days) was determined visually (expressed as percent non round cells) and by measuring the cell volume by Coulter Counter analysis. EGF treatment caused the cells to change their morphology with percent non round cells increasing from 37% in control cells to 74% in EGF-treated cultures; this was accompanied by a parallel increase in cell volume. Treatment of the cells with EGF in the presence of the MEK1 inhibitor (PD98059) completely blocked the EGF-induced morphological changes, showing that activation of the mitogen-activated protein kinase (MAPK) pathway is necessary to mediate this effect. Transfection of the cells with a constitutively activated mutant of MEK1 produced a similar morphological change to that produced by EGF treatment, with the proportion of non round cells increasing to 62% with a parallel increase in cell volume compared to cells transfected with the empty vector, demonstrating that direct activation of MAPK pathway is sufficient to mediate the observed morphological effects. The effects produced by activated MEK1 transfection could be blocked by PD98059. EGF had opposing effects on prolactin and growth hormone (GH) secretion by the cells, increasing prolactin release and inhibiting GH release. Transfection of the cells with activated MEK1 produced similar effects on hormone release as EGF treatment. In conclusion, the morphological effects of EGF on GH3 cells are mediated by activation of the MAPK pathway as blockade of this pathway abolished the observed effect, and direct activation of this pathway by transfection with an activated mutant of MEK1 was able to duplicate these effects. This mechanism may contribute to the growth and possibly local invasiveness of some pituitary tumours that express the EGF receptor.

Loss of ACTH expression in cultured human corticotroph macroadenoma cells is consistent with loss of the POMC gene signal sequence

The proopiomelanocortin (POMC) gene is highly expressed in the pituitary gland where the resulting mRNA of 1200 base pairs (bp) gives rise to a full-length protein sequence. In peripheral tissues however both shorter and longer POMC variants have been described, these include for example placental tissue which contain 800 (truncated at the 5' end) and 1500 as well as the 1200 bp transcripts. The importance of the 800 bp transcript is unclear as the lack of a signal sequence renders the molecule to be non-functional. This transcript has not been previously demonstrated in the pituitary gland. In this report we show evidence of a 5' truncated POMC gene in human pituitary corticotroph macroadenoma cells (JE) maintained in primary culture for >1 year. The original tumour tissue and the derived cells during early passage (up to passage 4-5) immunostained for ACTH and in situ hybridisation confirmed the presence of the POMC gene in the cultured cells. These cells also secreted 15-40 pg/10(5) cells/24 h ACTH. In addition, as expected RT-PCR demonstrated the presence of all three POMC gene exons and is thus indicative of a full-length POMC gene. In late culture passages (passages 8-15) JE cells ceased to express ACTH and cell growth became very slow due presumably to cells reaching their Hayflick limit. ACTH immunostaining in these cells was undetectable and ACTH secretion was also at the detection limits of the assay and no greater than 10 pg/10(5) cells/24 h. ACTH precursor molecules were also undetectable. RT-PCR for the POMC gene in these late passage cells showed that only exon 3 was detectable, in contrast to early passage cells where all three exons were present. In summary we isolated in culture, human pituitary cells that possessed initially all three exons of the POMC gene and immunostained for ACTH. On further passaging these cells showed a loss of exons 1 and 2 in the POMC gene and a loss of ACTH immunostaining and secretion. We would like to suggest that the loss of ACTH peptide expression in these late passage cells is in part due to the loss of the POMC signal sequence. An alternative explanation for our findings is that there were originally two populations of corticotrophs in the cultures, one of which possessed the full-length POMC gene and the other only the 5' truncated POMC transcript and it is these latter cells which survived in culture. In either scenario this is the first report of the 5' truncated POMC gene occurring in pituitary cells.