Pathogenic evaluation of a turkey coronavirus isolate (TCoV NC1743) in turkey poults for establishing a TCoV disease model

Turkey coronavirus (TCoV) can cause a highly contagious enteric disease in turkeys with severe economic losses in the global turkey industry. To date, no commercial vaccines are available for control of the disease. In the present study, we isolated a field strain (NC1743) of TCoV and evaluated its pathogenicity in specific-pathogen-free (SPF) turkey poults to establish a TCoV disease model. The results showed that the TCoV NC1743 isolate was pathogenic to turkey poults with a minimal infectious dose at 10⁶ EID₅₀/bird. About 50 % of one-day-old SPF turkeys infected with the virus's minimal infectious dose exhibited typical enteric disease signs and lesions from 6 days post-infection (dpi) to the end of the experiment (21 dpi). In contrast, fewer than 20 % of older turkeys (1- or 2-week-old) infected with the same amount of TCoV displayed enteric disease signs, which disappeared after 15-18 dpi. Although all infected turkeys, regardless of age, shed TCoV, the older turkeys shed less virus than the younger birds, and 50 % of the 2-week-old birds even cleared the virus at 21 dpi. Furthermore, the viral infection caused day-old turkeys more body-weight-gain reduction than older birds. The overall data demonstrated that the TCoV NC1743 isolate is a highly pathogenic strain and younger turkeys are more susceptible to TCoV infection than older birds. Thus, one-day-old turkeys infected with the minimal infectious dose of TCoV NC1743 could be used as a TCoV disease model to study the disease pathogenesis, and the TCoV NC1743 strain could be used as a challenge virus to evaluate a vaccine protective efficacy.

Isolation and genomic characterization of a novel avian orthoreovirus strain in Korea, 2014

In this study, we isolated a novel avian reovirus (ARV) strain, K738/14, from a broiler chicken with viral arthritis in South Korea. Genome sequence comparisons showed relatively low nucleotide identity with previously identified ARV strains. Phylogenetic analyses suggested multiple reassortment events between reovirus strain S1133 and reoviruses of Hungarian, Chinese, and US origin had occurred. In addition, recombination analyses showed evidence of intra-segmental recombination in the M2 and S2 genes. Based on our genetic analyses, multiple reassortment events, intra-segmental recombination, and accumulation of point mutations have possibly contributed to the emergence of this novel genotype of ARV, identified in Korea.

Molecular Characterization of Enteric Picornaviruses in Archived Turkey and Chicken Samples from the United States

Recent metagenomic analyses of the enteric viromes in turkeys and chickens have revealed complex viral communities comprised of multiple viral families. Of particular significance are the novel avian picobirnaviruses (family Picobirnaviridae), multiple genera of tailed phages (family Siphoviridae), and undescribed avian enteric picornaviruses (family Picornaviridae). In addition to these largely undescribed-and therefore relatively poorly understood-poultry enteric viral families, these metagenomic analyses have also revealed the presence of well-known groups of enteric viruses such as the chicken and turkey astroviruses (family Astroviridae) and the avian rotaviruses and reoviruses (family Reoviridae). The order Picornavirales is a group of viruses in flux, particularly among the avian picornaviruses, since several new genera have been described recently based upon community analysis of enteric viromes from poultry and other avian species worldwide. Our previous investigation of the turkey enteric picornaviruses suggests the avian enteric picornaviruses may contribute to the enteric disease syndromes and performance problems often observed in turkeys in the Southeastern United States. This report describes our recent phylogenetic analysis of turkey and chicken enteric samples archived at the Southeast Poultry Research Laboratory from 2004 to present and is a first step in placing these novel avian picornaviruses within the larger Picornaviridae family.

Investigating Turkey Enteric Picornavirus and Its Association with Enteric Disease in Poults

Previous research into the viral community in the poultry gastrointestinal tract has revealed a number of novel and partially described enteric viruses. It is evident that the poultry gut viral community remains minimally characterized and incompletely understood. Investigations into the microbiome of the poultry gut have provided some insight into the geographical distribution and the rapidly evolving taxonomy of the avian enteric picornaviruses. The present investigation was undertaken to produce a comparative metagenomic analysis of the gut virome from a healthy turkey flock versus a flock placed in the field. This investigation revealed a number of enteric picornavirus sequences that were present in the commercial birds in the field that were completely absent in the healthy flock. A novel molecular diagnostic assay was used to track the shedding of field strains of turkey enteric picornavirus in commercial poults inoculated with picornavirus-positive intestinal homogenates prepared from turkeys that were experiencing moderate enteric disease. The propagation of this novel enteric picornavirus in commercial poults resulted in significant reduction in weight gain, and suggests that this common inhabitant of the turkey gut may result in performance problems or enteric disease in the field.

Comparative analysis of the intestinal bacterial and RNA viral communities from sentinel birds placed on selected broiler chicken farms

There is a great deal of interest in characterizing the complex microbial communities in the poultry gut, and in understanding the effects of these dynamic communities on poultry performance, disease status, animal welfare, and microbes with human health significance. Investigations characterizing the poultry enteric virome have identified novel poultry viruses, but the roles these viruses play in disease and performance problems have yet to be fully characterized. The complex bacterial community present in the poultry gut influences gut development, immune status, and animal health, each of which can be an indicator of overall performance. The present metagenomic investigation was undertaken to provide insight into the colonization of specific pathogen free chickens by enteric microorganisms under field conditions and to compare the pre-contact intestinal microbiome with the altered microbiome following contact with poultry raised in the field. Analysis of the intestinal virome from contact birds ("sentinels") placed on farms revealed colonization by members of the Picornaviridae, Picobirnaviridae, Reoviridae, and Astroviridae that were not present in pre-contact birds or present in proportionally lower numbers. Analysis of the sentinel gut bacterial community revealed an altered community in the post-contact birds, notably by members of the Lachnospiracea/Clostridium and Lactobacillus families and genera. Members of the avian enteric Reoviridae and Astroviridae have been well-characterized and have historically been implicated in poultry enteric disease; members of the Picobirnaviridae and Picornaviridae have only relatively recently been described in the poultry and avian gut, and their roles in the recognized disease syndromes and in poultry performance in general have not been determined. This metagenomic analysis has provided insight into the colonization of the poultry gut by enteric microbes circulating in commercial broiler flocks, and has identified enteric viruses and virus communities that warrant further study in order to understand their role(s) in avian gut health and disease.

Investigating turkey enteric coronavirus circulating in the Southeastern United States and Arkansas during 2012 and 2013

Periodic monitoring of poultry flocks in the United States via molecular diagnostic methods has revealed a number of potential enteric viral pathogens in continuous circulation in turkeys and chickens. Recently turkey integrators in the Southeastern United States and Arkansas experienced an outbreak of moderate to severe enteritis associated with turkey enteric coronavirus (TCoV), and numerous enteric samples collected from turkey flocks in these areas tested positive for TCoV via real-time reverse-transcriptase PCR (RRT-PCR). This report details the subsequent sequence and phylogenetic analysis of the TCoV spike glycoprotein and the comparison of outbreak-associated isolates to sequences in the public database. TCoVs investigated during the present outbreak grouped geographically based upon state of origin, and the RRT-PCR assay was a good indicator of subsequent seroconversion by TCoV-positive turkey flocks.

In vivo and in vitro properties of STX2484: a novel non-steroidal anti-cancer compound active in taxane-resistant breast cancer

BACKGROUND

STX2484 is a novel non-steroidal compound with potent anti-proliferative activity. These studies aimed to identify STX2484's mechanism of action, in vivo efficacy and activity in taxane-resistant breast cancer models.

METHODS

Effects of STX2484 and paclitaxel on proliferation, cell cycle and apoptosis were assessed in vitro in drug-resistant (MCF-7(DOX)) and non-resistant cells (MCF-7(WT)). STX2484 efficacy in βIII tubulin overexpression in MCF-7 cells was also determined. Anti-angiogenic activity was quantified in vitro by a co-culture model and in vivo using a Matrigel plug assay. An MDA-MB-231 xenograft model was used to determine STX2484 efficacy in vivo.

RESULTS

STX2484 is a tubulin disruptor, which induces p53 expression, Bcl2 phosphorylation, caspase-3 cleavage, cell cycle arrest and apoptosis. In addition, STX2484 is a potent anti-angiogenic agent in vitro and in vivo. In breast cancer xenografts, STX2484 (20 mg kg(-1) p.o.) suppressed tumour growth by 84% after 35 days of daily dosing, with limited toxicity. In contrast to paclitaxel, STX2484 efficacy was unchanged in two clinically relevant drug-resistant models.

CONCLUSIONS

STX2484 is an orally bioavailable microtubule-disrupting agent with in vivo anti-angiogenic activity and excellent in vivo efficacy with no apparent toxicity. Crucially, STX2484 has superior efficacy to paclitaxel in models of clinical drug resistance.

Molecular and phylogenetic analysis of a novel turkey-origin picobirnavirus

A previous metagenomic analysis of the turkey gut RNA virus community identified novel enteric viruses that may play roles in poultry enteric diseases or in performance problems noted in the field. As part of the molecular characterization of these novel enteric viruses, a reverse transcriptase-PCR diagnostic assay was developed, targeting a novel turkey-origin picobirnavirus (PBV) initially identified in a pooled intestinal sample from turkey poults in North Carolina. Little detailed molecular information exists regarding the family Picobirnaviridae, particularly for the PBVs that have been described in avian species. This diagnostic assay targets the turkey PBV RNA-dependent RNA polymerase gene and produces an 1135-bp amplicon. This assay was validated using in vitro transcribed RNA and was tested using archived enteric samples collected from turkey flocks in the southeastern United States. Further, a phylogenetic analysis suggests the turkey PBV is unique because it does not group closely with the recognized PBV genogroups circulating in mammalian hosts.

Chicken parvovirus-induced runting-stunting syndrome in young broilers

Previously we identified a novel parvovirus from enteric contents of chickens that were affected by enteric diseases. Comparative sequence analysis showed that the chicken parvovirus (ChPV) represented a new member in the Parvoviridae family. Here, we describe some of the pathogenic characteristics of ChPV in young broilers. Following experimental infection, 2-day-old broiler chickens showed characteristic signs of enteric disease. Runting-stunting syndrome (RSS) was observed in four of five experimental groups with significant growth retardation between 7 and 28 days postinoculation (DPI). Viral growth in small intestine and shedding was detected at early times postinoculation, which was followed by viremia and generalization of infection. ChPV could be detected in most of the major tissues for 3 to 4 wk postinoculation. Immunohistochemistry staining revealed parvovirus-positive cells in the duodenum of inoculated birds at 7 and 14 DPI. Our data indicate that ChPV alone induces RSS in broilers and is important determinant in the complex etiology of enteric diseases of poultry.

The complete genome sequence and genetic analysis of ΦCA82 a novel uncultured microphage from the turkey gastrointestinal system

The genomic DNA sequence of a novel enteric uncultured microphage, ΦCA82 from a turkey gastrointestinal system was determined utilizing metagenomics techniques. The entire circular, single-stranded nucleotide sequence of the genome was 5,514 nucleotides. The ΦCA82 genome is quite different from other microviruses as indicated by comparisons of nucleotide similarity, predicted protein similarity, and functional classifications. Only three genes showed significant similarity to microviral proteins as determined by local alignments using BLAST analysis. ORF1 encoded a predicted phage F capsid protein that was phylogenetically most similar to the Microviridae ΦMH2K member's major coat protein. The ΦCA82 genome also encoded a predicted minor capsid protein (ORF2) and putative replication initiation protein (ORF3) most similar to the microviral bacteriophage SpV4. The distant evolutionary relationship of ΦCA82 suggests that the divergence of this novel turkey microvirus from other microviruses may reflect unique evolutionary pressures encountered within the turkey gastrointestinal system.

Metagenomic analysis of the turkey gut RNA virus community

Viral enteric disease is an ongoing economic burden to poultry producers worldwide, and despite considerable research, no single virus has emerged as a likely causative agent and target for prevention and control efforts. Historically, electron microscopy has been used to identify suspect viruses, with many small, round viruses eluding classification based solely on morphology. National and regional surveys using molecular diagnostics have revealed that suspect viruses continuously circulate in United States poultry, with many viruses appearing concomitantly and in healthy birds. High-throughput nucleic acid pyrosequencing is a powerful diagnostic technology capable of determining the full genomic repertoire present in a complex environmental sample. We utilized the Roche/454 Life Sciences GS-FLX platform to compile an RNA virus metagenome from turkey flocks experiencing enteric disease. This approach yielded numerous sequences homologous to viruses in the BLAST nr protein database, many of which have not been described in turkeys. Our analysis of this turkey gut RNA metagenome focuses in particular on the turkey-origin members of the Picornavirales, the Caliciviridae, and the turkey Picobirnaviruses.

Molecular characterization of avian astroviruses

Astroviruses are frequently associated with enteric diseases in poultry, being isolated from cases of runting-stunting syndrome (RSS) of broiler chickens, poult enteritis complex (PEC), and poult enteritis mortality syndrome (PEMS) of turkeys. Currently, five types of avian astrovirus have been identified: turkey astroviruses 1 and 2 (TAstV-1, TAstV-2), avian nephritis virus (ANV), chicken astrovirus (CAstV) and duck astrovirus (DAstV). The objective of this study was to molecularly characterize the different types of avian astroviruses circulating in commercial poultry. Sequence analysis of a region of ORF2, which encodes the capsid precursor protein associated with serotype and viral pathogenesis, revealed extensive variation in amino acid sequence within each subtype: TAstV-2 (81.5%-100%), ANV (69.9%-100%), and CAstV (85.3%-97.9%). However, this region was more conserved in TAstV-1's (96.2%-100%). Furthermore, a novel astrovirus was detected in chicken samples and found to be <64% similar to ANV and <30.6% similar to CAstV. The results of this study underline the great genetic variability of avian astroviruses and indicate that there are most likely multiple serotypes of each avian astrovirus circulating in commercial poultry.

17ß-hydroxysteroid dehydrogenase inhibitors

17ß-hydroxysteroid dehydrogenases (17ß-HSDs) are enzymes which require NAD(P)(H) for activity and are responsible for reduction or oxidation of hormones, fatty acids and bile acids in vivo, regulating the amount of the active form which is available to bind to its receptor. Fifteen 17b-HSDs have been identified to date, and with one exception, 17ß-HSD Type 5 (17ß-HSD5), an aldo-keto reductase, they are all short chain dehydrogenases/reductases. Although named as 17ß-HSDs, reflecting the major redox activity at the 17ß-position of the steroid, overall homology between the enzymes is low and the activities of these fifteen enzymes vary, with several of the 17ß-HSDs able to reduce and / or oxidise multiple substrates at various positions. These activities are involved in the progression of a number of diseases, including those related to steroid metabolism. Many groups are now working on inhibitors specific for several of these enzymes for the treatment of steroid-dependent diseases, including breast and prostate cancer, and endometriosis, with demonstrable efficacy in in vivo disease models, although none have yet reached clinical trials. In this review the recent advances in the development of specific inhibitors of the 17ß-HSD1, 3 and 5 enzymes as targets for the treatment of these diseases and the models used for their evaluation will be discussed.

Parvovirus-associated cerebellar hypoplasia and hydrocephalus in day old broiler chickens

Cerebellar hypoplasia and hydrocephalus were identified in day old broiler chickens showing nervous signs, impaired mobility, and diarrhea. At postmortem examination, brains of chickens were misshapen and cerebellums were smaller than normal. Microscopically, cerebellar folia were reduced in size and irregularly shaped, and the ventricles were widely distended. Affected cerebellums had focal areas along the base of folia where the internal granular cell layer had been lost, and Purkinje cells were disorganized and located within the molecular layer. Parvovirus DNA was detected by polymerase chain reaction in three of nine brains with oligonucleotide primers designed for amplification of chicken and turkey parvoviruses. On the basis of phylogenetic analyses, the detected virus was most closely related to chicken parvoviruses. These findings suggest that a chicken parvovirus might cause a neurologic disease of young chickens characterized by cerebellar hypoplasia and hydrocephalus; however, its role as the cause of the disease remains to be confirmed.

Astrovirus, reovirus, and rotavirus concomitant infection causes decreased weight gain in broad-breasted white poults

Turkey astrovirus type-2 (TAstV-2), turkey rotavirus (TRotV), and turkey reovirus (TReoV) have been implicated as possible causes of enteric diseases and poor production in turkeys; however, numerous studies with each individual virus have failed to reproduce the disease as observed in the field. Therefore, in this study we evaluated the pathogenesis of all possible combinations of one, two, or three viruses in comparison to sham inoculates in 3-day-old turkey poults. Body weights were recorded at 2, 4, 7, 10, and 14 days postinoculation (PI) and were decreased in virus-infected turkeys throughout the experiment as compared to sham inoculates. Although not significantly different from the other virus-exposed groups, the poults exposed to all three viruses had the lowest body weights throughout the experiment. Clinical signs, including huddling, diarrhea, and agitation, were only observed in groups exposed to TAstV-2 and/or TRotV. At 4 days PI, birds from each treatment group were necropsied, and pale intestines with watery contents and undigested feed were observed in the groups that were exposed to TRotV + TReoV or TRotV + TAstV-2 and the group exposed to all three viruses. Minimal microscopic lesions were observed in the intestines of turkeys infected with TAstV-2, TReoV, or a combination of both. In the turkeys infected with TRotV, either alone or in combination with other viruses, mild microscopic lesions were found in all sections of the small intestine and viral antigen was identified by immunohistochemical staining in mature enterocytes. No or very mild lesions were observed in other organs with the exception of the bursa of Fabricius, where mild to severe atrophy was observed in all virus-infected poults examined. Cloacal shedding of TAstV-2 and TRotV was evaluated by reverse-transcription PCR testing of cloacal swabs and minimal differences were observed among the treatment groups.

Myocarditis associated with reovirus in turkey poults

Myocarditis associated with reovirus was diagnosed in 17-day-old, male turkey poults, based on virus isolation, reverse transcriptase-polymerase chain reaction (RT-PCR), demonstration of reovirus antigen in the cytoplasm of mononuclear inflammatory cells and myocytes in the heart by immunohistochemistry (IHC), and reovirus particles in the endoplasmic reticulum of myocytes by transmission electron microscopy (TEM). Clinical signs in the poults included anorexia, growth depression, and increased mortality. Gross lesions in the six poults examined were increased pericardial fluid, mild-to-moderate dilation of right ventricles, pale-yellow myocardium, and ascites. Other lesions in a few birds included mild pulmonary edema, congestion, and pale serosa of the small intestine that had watery contents in their lumens. Microscopically, in the heart, there was mild-to-severe necrosis of myocytes and infiltration of primarily lymphocytes mixed with a few heterophils, macrophages, and occasionally, plasma cells and multinucleated giant cells. There was mild-to-moderate lymphoid depletion in the bursa of Fabricius. Reovirus was isolated from the heart of the turkey poults in chicken-embryo liver cells and was confirmed by RT-PCR, IHC, and TEM. A retrospective search of the laboratory database for cases of myocarditis associated with reovirus in turkeys revealed that this condition has occurred sporadically in California turkey flocks since 1991. This is the first documentation of myocarditis in turkey poults associated with reovirus.

Determination and analysis of the full-length chicken parvovirus genome

Viral enteric disease in poultry is an ongoing problem in many parts of the world. Many enteric viruses have been identified in turkeys and chickens, including avian astroviruses, rotaviruses, reoviruses, and coronaviruses. Through the application of a molecular screening method targeting particle-associated nucleic acid (PAN), we recently described the detection and partial characterization of a novel enteric parvovirus in chickens. Subsequent surveys of intestinal homogenates from turkeys and chickens in the United States revealed widespread occurrence of parvovirus in poultry. Here we report the first full genome sequence of a novel chicken parvovirus, ChPV ABU-P1. ChPV ABU-P1 genome organization, predicted amino acid sequence, and phylogenetic relationships with other described parvoviruses are discussed.

BCRP expression does not result in resistance to STX140 in vivo, despite the increased expression of BCRP in A2780 cells in vitro after long-term STX140 exposure

The anti-proliferative and anti-angiogenic properties of the endogenous oestrogen metabolite, 2-methoxyoestradiol (2-MeOE2), are enhanced in a series of sulphamoylated derivatives of 2-MeOE2. To investigate possible mechanisms of resistance to these compounds, a cell line, A2780.140, eightfold less sensitive to the 3,17-O,O-bis-sulphamoylated derivative, STX140, was derived from the A2780 ovarian cancer cell line by dose escalation. Other cell lines tested did not develop STX140 resistance. RT-PCR and immunoblot analysis demonstrated that breast cancer resistance protein (BCRP) expression is dramatically increased in A2780.140 cells. The cells are cross-resistant to the most structurally similar bis-sulphamates, and to BCRP substrates, mitoxantrone and doxorubicin; but they remain sensitive to taxol, an MDR1 substrate, and to all other sulphamates tested. Sensitivity can be restored using a BCRP inhibitor, and this pattern of resistance is also seen in a BCRP-expressing MCF-7-derived cell line, MCF-7.MR. In mice bearing wild-type (wt) and BCRP-expressing tumours on either flank, both STX140 and mitoxantrone inhibited the growth of the MCF-7wt xenografts, but only STX140 inhibited growth of the MCF-7.MR tumours. In conclusion, STX140, a promising orally bioavailable anti-cancer agent in pre-clinical development, is highly efficacious in BCRP-expressing xenografts. This is despite an increase in BCRP expression in A2780 cells in vitro after chronic dosing with STX140.

The diversity of the orthoreoviruses: molecular taxonomy and phylogentic divides

The family Reoviridae is a diverse group of viruses with double-stranded RNA genomes contained within icosahedral, non-enveloped, double-layered protein capsids. Within the Reoviridae, the Orthoreovirus genus includes viruses that infect reptiles, birds and mammals (including humans). Recent sequencing efforts have produced a great deal of new molecular data for the fusogenic orthoreoviruses, a group of reoviruses that induce cell-cell fusion during an infection. This new data has allowed a fresh look at the phylogenetic relationships among the members of the Orthoreovirus genus, and has provided insight into the evolution of orthoreovirus species and species groups. This review mainly focuses on the molecular taxonomy of the fusogenic orthoreoviruses, and aims to provide insight into their relationships with the non-fusogenic orthoreoviruses and other selected Reoviridae genera.

Turkey origin reovirus-induced immune dysfunction in specific pathogen free and commercial turkey poults

Recently, pathogenesis studies, using genetically distinct turkey-origin reoviruses (TRVs), revealed that poults infected with certain TRV isolates had moderate to severe bursal atrophy, suggesting virus-induced immune dysfunction. In order to characterize the effect of TRV infection on the turkey immune system, classical assays were undertaken to quantify the humoral and cell-mediated immune responses in small Beltsville and broad-breasted white poults infected with the TRV isolate NC/SEP-R44/03. A marked effect on the cutaneous basophil hypersensitivity response, and on the antibody response to Newcastle disease virus (NDV) exposure, was noted in commercial and specific pathogen free (SPF) poults inoculated with NC/SEP-R44/03 at three days of age. Moderate to severe bursal atrophy, similar to that noted previously in SPF poults, occurred in commercial poults inoculated at three days of age. This immune dysfunction and bursal atrophy was not present in commercial poults inoculated at three weeks of age.

Pathogenesis of type 2 turkey astroviruses with variant capsid genes in 2-day-old specific pathogen free poults

The pathogenicity of three different type 2 turkey astroviruses (TAstV-2) was studied in specific pathogen free turkeys. These viruses differ based on sequence analysis of the capsid gene. Poults were inoculated at 2 days of age and examined during 14 days for clinical signs and virus shedding. All inoculated poults presented signs of enteric disease including diarrhoea and growth depression. Virus presence and shedding was detected by real-time reverse transcriptase-polymerase chain reaction from intestinal contents and cloacal swabs collected at 3, 7 and 14 days post-inoculation. Viraemia was also confirmed by this method. Common lesions observed at necropsy were dehydration; distended intestines filled with watery contents and undigested feed, and dilated caeca with foamy contents. Microscopic lesions present in the intestines consisted of mild crypt hyperplasia, villous atrophy and lymphocytic infiltration, and were most common in the jejunum. Presence of the viruses was demonstrated by immunohistochemistry and by in situ hybridization in both villi and crypt enterocytes in the jejunum and, less frequently, the duodenum, ileum and caeca. Mild lesions consisting mainly of lymphocytic infiltration were also observed in other organs including the pancreas, liver, spleen and kidneys. Mild to moderate bursal atrophy occurred in all TAstV-2-infected poults examined; however, no specific viral staining was observed in this organ or any other tissues examined apart from the intestines. In conclusion, TAstV-2 viruses with variant capsids produce a similar enteric disease in young turkeys and may also affect the immune system of the birds by causing bursal lymphoid depletion.

Enteric viruses detected by molecular methods in commercial chicken and turkey flocks in the United States between 2005 and 2006

Intestinal samples collected from 43 commercial broiler and 33 commercial turkey flocks from all regions of the United States during 2005 and 2006 were examined for the presence of astrovirus, rotavirus, reovirus, and coronavirus by reverse transcription-polymerase chain reaction (PCR), and for the presence of groups 1 and 2 adenovirus by PCR. Phylogenetic analysis was performed to further characterize the viruses and to evaluate species association and geographic patterns. Astroviruses were identified in samples from 86% of the chicken flocks and from 100% of the turkey flocks. Both chicken astrovirus and avian nephritis virus (ANV) were identified in chicken samples, and often both viruses were detected in the same flock. Turkey astrovirus type-2 and turkey astrovirus type-1 were found in 100% and 15.4% of the turkey flocks, respectively. In addition, 12.5% of turkey flocks were positive for ANV. Rotaviruses were present in 46.5% of the chicken flocks tested and in 69.7% of the turkey flocks tested. Based upon the rotavirus NSP4 gene sequence, the chicken and turkey origin rotaviruses assorted in a species-specific manner. The turkey origin rotaviruses also assorted based upon geographical location. Reoviruses were identified in 62.8% and 45.5% of chicken and turkey flocks, respectively. Based on the reovirus S4 gene segment, the chicken and turkey origin viruses assorted separately, and they were distinct from all previously reported avian reoviruses. Coronaviruses were detected in the intestinal contents of chickens, but not turkeys. Adenoviruses were not detected in any chicken or turkeys flocks. Of the 76 total chicken and turkey flocks tested, only three chicken flocks were negative for all viruses targeted by this study. Most flocks were positive for two or more of the viruses, and overall no clear pattern of virus geographic distribution was evident. This study provides updated enteric virus prevalence data for the United States using molecular methods, and it reinforces that enteric viruses are widespread in poultry throughout the United States, although the clinical importance of most of these viruses remains unclear.

Periodic monitoring of commercial turkeys for enteric viruses indicates continuous presence of astrovirus and rotavirus on the farms

A longitudinal survey to detect enteric viruses in intestinal contents collected from turkeys in eight commercial operations and one research facility was performed using molecular detection methods. Intestinal contents were collected from turkeys prior to placement, with each flock resampled at 2, 4, 6, 8, 10, and 12 wk of age. The samples were screened for astrovirus, rotavirus, reovirus, and turkey coronavirus (TCoV) by a reverse transcriptase and polymerase chain reaction (RT-PCR), and for groups 1 and 2 adenovirus by PCR. Rotavirus was the only virus detected prior to placement (7 of 16 samples examined). All of the commercial flocks were positive for rotavirus and astrovirus from 2 until 6 wk of age, and most were intermittently positive until 12 wk of age, when the birds were processed. Of the 96 samples collected from birds on the farms, 89.5% were positive for astrovirus, and 67.7% were positive for rotavirus. All flocks were negative for TCoV, reovirus, and group 1 adenovirus at all time points, and positive for group 2 adenovirus (hemorrhagic enteritis virus) at 6 wk of age. All the flocks monitored were considered healthy or normal by field personnel. Turkeys placed on research facilities that had been empty for months and thoroughly cleaned had higher body weights and lower feed conversion rates at 5 wk of age when compared to turkeys placed on commercial farms. Intestinal samples collected at 1, 2, and 3 wk of age from these turkeys were free of enteric viruses. This report demonstrates that astroviruses and rotaviruses may be present within a turkey flock through the life of the flock. Comparison of infected birds with one group of turkeys that were negative for enteric viruses by the methods used here suggests that astrovirus and/or rotavirus may affect production. The full impact on flock performance needs to be further determined.

The therapeutic potential of a series of orally bioavailable anti-angiogenic microtubule disruptors as therapy for hormone-independent prostate and breast cancers

Therapies for hormone-independent prostate and breast cancer are limited, with the effectiveness of the taxanes compromised by toxicity, lack of oral bioavailability and drug resistance. This study aims to identify and characterise new microtubule disruptors, which may have improved efficacy relative to the taxanes in hormone-independent cancer. 2-Methoxy-3-O-sulphamoyl-17β-cyanomethyl-oestra-1,3,5(10)-triene (STX641), 2-methoxy-3-hydroxy-17β-cyanomethyl-oestra-1,3,5(10)-triene (STX640) and 2-methoxyoestradiol-3,17-O,O-bis-sulphamate (STX140) were all potent inhibitors of cell proliferation in a panel of prostate and breast cancer cell lines. STX641 and STX640 significantly inhibited tumour growth in the MDA-MB-231 xenograft model. STX641 inhibited both in vitro and in vivo angiogenesis. Despite good in vivo activity, STX641 was not as potent in vivo as STX140. Therefore, STX140 was evaluated in the prostate hormone-independent PC-3 xenograft model. STX140 had superior efficacy to docetaxel, 2-MeOE2 and bevacizumab. In contrast to vinorelbine, no significant toxicity was observed. Furthermore, STX140 could be dosed daily over a 60-day period leading to tumour regression and complete responses, which were maintained after the cessation of dosing. This study demonstrates that STX641 and STX140 have considerable potential for the treatment of hormone-independent breast and prostate cancer. In contrast to the taxanes, STX140 can be dosed orally, with no toxicity being observed even after prolonged daily dosing.

Sequence and phylogenetic analysis of the S1 genome segment of turkey-origin reoviruses

Based on previous reports characterizing the turkey-origin avian reovirus (TRV) sigmaB (sigma2) major outer capsid protein gene, the TRVs may represent a new group within the fusogenic orthoreoviruses. However, no sequence data from other TRV genes or genome segments has been reported. The sigmaC protein encoded by the avian reovirus S1 genome segment is the cell attachment protein and a major antigenic determinant for avian reovirus. The chicken reovirus S1 genome segment is well characterized and is well conserved in viruses from that species. This report details the amplification, cloning and sequencing of the entire S1 genome segment from two and the entire coding sequences of the sigmaC, p10 and p17 genes from an additional five TRVs. Sequence analysis reveals that of the three proteins encoded by the TRV S1 genome segment, sigmaC shares at most 57% amino acid identity with sigmaC from the chicken reovirus reference strain S1133, while the most similar p10 and p17 proteins share 72% and 61% identity, respectively, with the corresponding S1133 proteins. The most closely related mammalian reovirus, the fusogenic Nelson Bay reovirus, encodes a sigmaC protein that shares from 25% to 28% amino acid identity with the TRV sigmaC proteins. This report supports the earlier suggestion that the TRVs are a separate virus species within the Orthoreovirus genus, and may provide some insight into TRV host specificity and pathogenesis.

Pathology and virus tissue distribution of Turkey origin reoviruses in experimentally infected Turkey poults

The pathogenesis of 4 isolates of turkey-origin reovirus (NC/SEP-R44/03, NC/98, TX/98, and NC/85) and 1 chicken-origin reovirus (1733) was examined by infecting specific pathogen free (SPF) poults. These turkey-origin reovirus (TRV) isolates were collected from turkey flocks experiencing poult enteritis and are genetically distinct from previously reported avian reoviruses. Microscopic examination of the tissues collected from the TRV-infected poults revealed different degrees of bursal atrophy characterized by lymphoid depletion and increased fibroplasia between the bursal follicles. To understand the relationship between virus spread and replication, and the induction of lesions, immunohistochemical staining (IHC) for viral antigen, in situ hybridization (ISH) for the detection of viral RNA, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay for the detection of apoptosis in affected tissues was performed. Both IHC and ISH revealed viral antigen and RNA in the surface epithelial cells of the bursa, in macrophages in the interstitium of the bursa and, to lesser degree, in splenic red pulp macrophages and intestinal epithelial cells. Increased apoptosis of bursal lymphocytes and macrophages was observed at 2 and 5 days postinoculation. No lesions were found in tissues from poults inoculated with the virulent chicken-origin strain, however viral antigen was detected in the bursa and the intestine. Although all TRVs studied displayed similar tissue tropism, there were substantial differences in the severity of the lesions produced. Poults inoculated with NC/SEP-R44/03 or NC/98 had moderate to severe bursal atrophy, whereas poults inoculated with TX/98 or NC/85 presented a mild to moderate bursal lymphoid depletion. The lymphoid depletion observed in the bursa appears to be the effect of an indirectly induced apoptosis and would most likely result in immune dysfunction in poults infected with TRV.

Structural analysis of kasugamycin inhibition of translation

The prokaryotic ribosome is an important target of antibiotic action. We determined the X-ray structure of the aminoglycoside kasugamycin (Ksg) in complex with the Escherichia coli 70S ribosome at 3.5-A resolution. The structure reveals that the drug binds within the messenger RNA channel of the 30S subunit between the universally conserved G926 and A794 nucleotides in 16S ribosomal RNA, which are sites of Ksg resistance. To our surprise, Ksg resistance mutations do not inhibit binding of the drug to the ribosome. The present structural and biochemical results indicate that inhibition by Ksg and Ksg resistance are closely linked to the structure of the mRNA at the junction of the peptidyl-tRNA and exit-tRNA sites (P and E sites).

The regulation and inhibition of 17beta-hydroxysteroid dehydrogenase in breast cancer

17Beta-hydroxysteroid dehydrogenase Type 1 (17beta-HSD1) has a pivotal role in regulating the synthesis of oestradiol (E2) within breast tumours. In whole body studies in postmenopausal women with breast cancer the conversion of oestrone (E1) to E2 (4.4+/-1.1%) was much lower than the inactivation of E2 to E1 (17.3+/-5.0%). In contrast, an examination of in vivo oestrogen metabolism within breast tumours revealed that whereas little metabolism of E2 occurred, E1 was converted to E2 to a much greater extent in malignant (48+/-14%) than in normal (19+/-6%) breast tissue. Findings from these studies originally suggested that oestrogen metabolism within breast tumours may differ from the mainly oxidative direction found in most other body tissues and that the activity of 17beta-HSD1 might be regulated by tumour-derived factors. Several growth factors (e.g. IGF-I, IGF-II) and cytokines (e.g. IL-6, TNFalpha) have now been identified which can markedly stimulate the activity of 17beta-HSD1 and such a mechanism may account for the high concentrations of E2 found in most breast tumours. Cells of the immune system, which can infiltrate breast tumours, are thought to be a major source of the growth factors and cytokines which can modulate 17beta-HSD1 activity. Given the central role that 17beta-HSD1 has in regulating breast tumour E2 concentrations the development of potent inhibitors of this enzyme has recently attracted considerable attention. Our initial studies in this area explored the use of derivatives of E1 as inhibitors, with 2-ethyl- and 2-methoxy E1 being found to inhibit 17beta-HSD1 activity in T-47D breast cancer cells by 96+/-2 and 91+/-1% respectively at 10 microM, but with a lack of specificity. Using the E1 scaffold a number of potent, selective 17beta-HSD1 inhibitors have now been identified including E1- and 2-ethyl-E1 containing a side chain with a m-pyridylmethylamidomethyl functionality extending from the 16beta position of the steroid nucleus. At 10 microM these compounds both inhibited 17beta-HSD1 activity by >90%, however some inhibition of 17beta-HSD2 activity was exhibited by the E1 derivative (25%) but not the 2-ethyl analogue. It is now apparent that 17beta-HSD1 activity contributes to the high E2 concentrations found in most breast tumours. The identification of potent, selective novel 17beta-HSD1 inhibitors will allow their efficacy to be tested in in vitro and in vivo studies.

The pathogenesis of turkey origin reoviruses in turkeys and chickens

Avian reoviruses that have been shown to be genetically distinct from chicken origin reoviruses were isolated from commercial turkey flocks in the Southeastern US and Texas that were experiencing enteritis. The pathogenesis of these turkey origin reoviruses (TRVs) was evaluated in commercial and specific pathogen free (SPF) turkey poults and SPF chickens. Mortality, clinical disease, gross lesions, microscopic lesions and body weights were observed. TRVs replicated poorly and did not cause disease in chickens. Clinical disease induced by the TRV isolates, characterized by diarrhoea and depression, was mild in both SPF and commercial origin poults. Several TRV isolates caused moderate to severe bursal atrophy in poults. Additionally, each of the TRV isolates caused significant body weight decreases in SPF and/or commercial poults as compared with sham inoculates. Molecular characterization of the isolates revealed that the TRVs and chicken origin reoviruses had identical electropherotype profiles.

The nature of inhibition of steroid sulphatase activity by tibolone and its metabolites

Tibolone is used for hormone replacement therapy and acts in a tissue-specific manner being oestrogenic on CNS and bone but not on breast tissues or endometrium. The ability of tibolone and its metabolites to inhibit steroid sulphatase (STS) activity has a crucial role in regulating its tissue-specific effects. In this study, we have examined the ability of tibolone and its non-sulphated and sulphated metabolites to inhibit STS activity in different enzyme preparations and in intact cells. For this, we have used an 'extracellular' method, which measures the amount of product released into culture medium, and an 'intracellular' method, which assesses the extent of product formation within cells. In addition, the nature by which tibolone and some of its metabolites inhibit STS activity was investigated using intact cells and an enzyme kinetic method. In MCF-7 and T47D breast cancer cells and JEG-3 choriocarcinoma cells, which have high STS activity, tibolone and its metabolites were relatively potent inhibitors of STS activity (33-57% inhibition at 10 microM) using the extracellular assay method. In HOS-TE-85 osteoblast-like cells, tibolone and its Delta-4 metabolite were relatively inactive whereas the 3alpha/3beta-hydroxy metabolites and their sulphated conjugates inhibited activity by 39-55%. When STS activity was assessed in HOS-TE-85 cells using an 'intracellular' method tibolone and its 3beta-hydroxy metabolite were inactive. Pre-treatment of breast cancer cells and JEG-3 cells, and removal of drugs prior to assaying for STS activity, revealed that in these cells tibolone and its metabolites were acting mainly as reversible inhibitors. This finding was confirmed in an enzyme kinetic study to measure concentration-dependent STS inhibition. In HOS-TE-85 cells, pre-treatment of cells and removal of compounds before assaying for remaining STS activity indicated that some tibolone metabolites appeared to stimulate STS activity. Possible mechanisms by which this might occur are discussed but, if confirmed, this could contribute to the positive oestrogenic effects that tibolone has on bone.

Isolation and characterization of ribosomes and translation initiation factors from the gram-positive soil bacterium Streptomyces lividans

A primer extension inhibition (toeprint) assay was developed using ribosomes and ribosomal subunits from Streptomyces lividans. This assay allowed the study of ribosome binding to streptomycete leaderless and leadered mRNA. Purified 30S subunits were unable to form a ternary complex on aph leaderless mRNA, whereas 70S ribosomes could form ternary complexes on this mRNA. 30S subunits formed ternary complexes on leadered aph and malE mRNA. The translation initiation factors (IF1, IF2, and IF3) from S. lividans were isolated and included in toeprint and filter binding assays with leadered and leaderless mRNA. Generally, the IFs reduced the toeprint signal on leadered mRNA; however, incubation of IF1 and IF2 with 30S subunits that had been washed under high-salt conditions promoted the formation of a ternary complex on aph leaderless mRNA. Our data suggest that, as reported for Escherichia coli, initiation complexes with leaderless mRNAs might use a novel pathway involving 70S ribosomes or 30S subunits bound by IF1 and IF2 but not IF3. Some mRNA-ribosome-initiator tRNA reactions that yielded weak or no toeprint signals still formed complexes in filter binding assays, suggesting the occurrence of interactions that are not stable in the toeprint assay.

Use of Competitive PCR to Detect and Quantify Haplosporidium nelsoni Infection (MSX disease) in the Eastern Oyster (Crassostrea virginica)

This study was undertaken to develop a quantitative polymerase chain reaction assay that would improve the utility of PCR for detecting Haplosporidium nelsoni (MSX), a serious parasite of the eastern oyster Crassostrea virginica. A competitive PCR sequence was generated from the H. nelsoni small subunit ribosomal DNA fragment, originally described by Stokes and colleagues, that was amplified by the same PCR primers and had similar amplification performance. Assays performed using competitor dilutions ranging from 0.05 to 500 pg/µl DNA were used to test oyster samples designated using histological techniques as having "light" or "heavy" MSX infections. Visual diagnoses were confirmed equally well with three methods: densitometry of ethidium-bromide-stained agarose, densitometry of SYBRGreen-stained polyacrylamide gels, and analysis by GeneScan 3.0 of fluorescent products detected in ultrathin gels. Oysters diagnosed as negative for MSX tested as negative or light by PCR. Oysters with light MSX infections generally had less than 5 pg/µl infectious DNA. Oysters with heavy infections generally corresponded to 5 pg/µl or greater competitor dilutions.

The folded protein modules of the C-terminal G3 domain of aggrecan can each facilitate the translocation and secretion of the extended chondroitin sulfate attachment sequence

Aggrecan is a multidomain proteoglycan containing both extended and folded protein modules. The C-terminal G3 domain contains a lectin-like, complement regulatory protein-like, and two alternatively spliced epidermal growth factor-like modules. It has been proposed that the lectin module alone has a necessary role in the intracellular translocation and secretion of proteins expressed containing G3. Constructs containing human aggrecan G3 together with 1155 bases of the adjacent chondroitin sulfate attachment region (CS-2) were prepared with different combinations and deletions of the protein modules and transfected into mammalian cells of monkey or hamster origin. The results showed that the products containing only the unfolded protein sequences (CS-2 with or without the C-terminal tail sequence) were translated and accumulated intracellularly but were not secreted. In contrast the constructs containing any of the folded protein modules and the extended CS-2 region were translated and secreted from the cells. The results show that the lectin module was not unique in facilitating the intracellular translocation and secretion of the G3 domain. The conservation of G3-like domains within the aggrecan family of proteoglycans may therefore result from their participation in other extracellular functions.

Effect of topical butyrate on rectal epithelial kinetics and mucosal enzyme activities

1. This study aimed to determine the effect of luminal butyrate on proliferative kinetics, a differentiation marker (alkaline phosphatase), and a molecule that controls cell-substratum adhesion (urokinase) in histologically normal human rectal mucosa. 2. Ten subjects with a colonoscopically normal colon (seven had previous adenomas) were given either butyrate or saline enemas for 4 days in a double-blind cross-over manner. Rectal biopsies were taken before and after each course of enemas. Epithelial proliferative kinetics were measured immunohistochemically using antibodies to proliferating cell nuclear antigen. Urokinase and alkaline phosphatase activities were measured spectrophotometrically in biopsy homogenates. 3. Both saline and butyrate enemas were well tolerated and induced no histological change except for a significant increase in crypt length (P < 0.05). The number of proliferating cells per crypt also increased significantly after butyrate (P = 0.018). 4. Compared with saline enemas, butyrate did not affect kinetic indices nor alkaline phosphatase activities. However, mucosal urokinase activities were significantly lower in butyrate-treated patients (9.5 +/- 2.0 i.u./g) than in saline-treated patients (12.8 +/- 2.0 i.u./g; P = 0.045). 5. Delivering of extra butyrate to the distal colon in healthy subjects may stabilize cell-substratum adhesion in surface epithelium and therefore offer a potential mechanism by which elevating distal colonic luminal butyrate concentrations might be beneficial in patients with colitis or hyperproliferative large bowel epithelium.

Effect of growth hormone on height, weight, and body composition in Prader-Willi syndrome

AIMS

To evaluate the effect of the administration of growth hormone on stature, body weight, and body composition in children aged between 4 and 10 years with Prader-Willi syndrome.

METHODS

Height, weight, and skinfold thickness were recorded in 25 children using standard anthropometric techniques at recruitment, and six months later, shortly before the start of daily subcutaneous injections of growth hormone. Body composition was assessed via a measurement of total body water using stable isotopes. Measurements were repeated at the end of the six months of growth hormone administration. Measurements of height, weight, and skinfold thickness were expressed as standard deviation scores (SDSs).

RESULTS

There was a significant reduction in the percentage of body fat after growth hormone treatment; height velocity doubled during treatment; body weight did not change significantly when expressed as an SDS. Skinfold thickness at both the triceps and subscapular site decreased in absolute terms and when expressed as an SDS.

CONCLUSIONS

These results indicate sufficient potential benefit to justify a more prolonged trial of growth hormone treatment and an exploration of different dosage regimens in children with Prader-Willi syndrome.

Energy intake in early infancy and childhood fatness

OBJECTIVE

To investigate whether aspects of infant energy intake are related to fatness in early childhood.

DESIGN

Longitudinal investigation of infants studied at 12 weeks and 2-3.5 y.

SUBJECTS

20 healthy infants, breast-fed or formula-fed, from the general population.

MEASUREMENTS

Milk volume intake (MVI) by deuterium turnover, estimated energy intake, weaning status and body composition in infancy, body composition in childhood.

RESULTS

MVI was not related to infant skinfolds or percentage fat. Weaning was inversely related to MVI (P < 0.04) at 12 weeks, and inversely related to skinfolds (P = 0.055) and fat mass (P = 0.020) in childhood. MVI and total energy intake were not related to childhood fatness.

CONCLUSIONS

Early weaning was associated with a moderate reduction in childhood fatness. Two possible mechanisms are discussed. However, early infant energy intake was not an important determinant of later fatness in this population.

Investigation of the relationship between infant temperament and later body composition

OBJECTIVE

To investigate the ability of maternally-rated infant temperament to predict fatness and activity patterns in early childhood.

DESIGN

Longitudinal investigation of infants studied at 12 weeks and followed up at 2-3.5 y of age.

SUBJECTS

Thirty healthy full-term infants from the general population.

MEASUREMENTS

Body composition, behavioural activity and temperament at 12 weeks; anthropometry, body composition, diet and behavioural activity at follow-up.

RESULTS

Infant temperament predicted later behaviour and fatness. Easily soothable infants had leaner childhood skinfold thicknesses (P < 0.02) and were more active in childhood (P < 0.025). Infant distress was also related to childhood diet composition.

CONCLUSIONS

Infant temperament can predict later body composition and behaviour. Both energy intake and energy expenditure may be mechanisms by which the relationship develops.

Total energy expenditure in 9 month and 12 month infants

OBJECTIVES

To measure the total energy expenditure of 9 and 12 month old infants and compare with current recommendations for energy intake.

DESIGN

Cross-sectional study. Total energy expenditure assessed using the doubly labelled water technique over a 10 d period. Classical anthropometric measurements taken.

SETTING

Community based study in and around Cambridge, UK.

SUBJECTS

Twenty infants aged 9 months of age and 20 infants aged 12 months of age recruited via local hospital birth records.

MAIN OUTCOME MEASURES

Total energy expenditure calculated via the doubly labelled water technique.

RESULTS

Measurements of total energy expenditure was successful in 34 cases. Mean total energy expenditure was 73.5 kcal/kg, 73.2 kcal/kg, 77.1 kcal/kg and 77.6 kcal/kg in the nine month old boys, nine month old girls, twelve month old boys and twelve month old girls respectively. These measurements are approximately 17% below current recommendations (FAO/WHO/UNU, 1985) at nine months of age and 22% below at one year of age.

CONCLUSION

The data are consistent with findings in younger infants and older children in that the measurements of total energy expenditure are about 20-25% below current recommendations. It is unlikely that contemporary infants are being underfed and thus more likely that changes in feeding practices and modification of infant formula composition has led to the reduction in energy intake and energy expenditure in such infants.

Measurement of total body water and urea kinetic modelling in peritoneal dialysis

Studies of the effect of Kt/V (urea) on prediction of outcome in patients on peritoneal dialysis have shown conflicting results. We performed this study to examine the effects of the measurement of V by varying techniques on the calculation of Kt/V, using body water estimated by deuterium oxide dilution (D2O dilution) as the criterion method for estimation of V. Studies were performed in 20 peritoneal dialysis patients. Kt was calculated from 24-hour dialysate and urine collections and V estimated by D2O dilution, Watson formulae, 58% of body weight, bioelectrical impedance (BIA) and 73% of fat-free mass estimated by DEXA. V was also measured in 35 healthy controls. Hydration, expressed as body water by D2O dilution as a percentage of fat-free mass estimated by DEXA did not differ between peritoneal dialysis patients 71.0 (4.9)% and a healthy control group 71.1 (5.0)%. Mean Kt/V using D2O dilution was 2.14 (0.36). The other techniques resulted in a significantly lower Kt/V; Watson equations 2.01 (0.35), p < 0.005, BIA 1.93 (0.31), p < 0.0001, DEXA 2.06 (0.28), p < 0.05, 58% body weight 1.83 (0.38), p < 0.0001. Limits of agreement of Kt/V by the simpler techniques compared with D2O dilution [mean difference of (other techniques -D2O dilution) as % of mean values +/- 95% limits of agreement] were Watson equation -5.9 +/- 15.3%, BIA -10.1 +/- 15.5%, DEXA -3.4 +/- 13.5% and 58% body weight -9.9 +/- 23.5%. Differences in Kt/V from estimates using D2O dilution were significantly negatively correlated with body fat for 58% body weight (r = -0.80, p < 0.0001) and the Watson formulae (r = -0.49, p < 0.05) but not for BIA or DEXA. We conclude that clinically significant variation in Kt/V may occur due to the estimation of V and may account for the uncertainty of the value of Kt/V as a predictor of outcome in peritoneal dialysis patients. Estimating V by BIA and DEXA did not have any benefit over the Watson formulae in terms of agreement with D2O dilution, though did avoid systematic errors related to body fat. Estimation of V as a fixed proportion of body weight is clearly inferior to the other techniques.

Four-component model of body composition in chronic renal failure comprising dual-energy X-ray absorptiometry and measurement of total body water by deuterium oxide dilution

1. Assessment of nutrition in patients with chronic renal failure by body composition measurement techniques may be affected by variable hydration. 2. This study aimed to derive a four-component model of body composition (consisting of fat, protein, total body water and body mineral) from a combination of dual-energy X-ray absorptiometry and total body water measured by deuterium oxide dilution, allowing assessment of body protein stores without the effect of variation in hydration. Patients with chronic renal failure on haemodialysis, peritoneal dialysis and conservative treatment and a control group were studied. Patients with chronic renal failure were at an 'ideal' state of hydration on clinical assessment. 3. Hydration was defined by total body water as a percentage of fat-free mass measured by dual-energy X-ray absorptiometry, and no differences were found between chronic renal failure subgroups and control subjects (except in the female undialysed chronic renal failure subgroup). Hydration was significantly correlated with percentage total body fat in the control groups but not in patients with chronic renal failure. 4. Lean tissue measured by dual-energy X-ray absorptiometry was significantly reduced in three of the six chronic renal failure groups compared with control subjects (male and female patients on haemodialysis and female patients on peritoneal dialysis). Protein estimated from the four-component model failed to detect these abnormalities. 5. Lean tissue measured by dual-energy X-ray absorptiometry in normal subjects strongly correlated with fat-free mass measured by total body potassium in normal subjects (male r = 0.91; female r = 0.89, both P < 0.0001). The correlation of protein estimated from the four-component model with fat-free mass measured by total body potassium was far weaker in male control subjects (r = 0.51, P < 0.05) and not significant in female control subjects (r = 0.38, P not significant). In the normal subjects protein estimated from the four-component model showed a much greater variation from protein estimated by total body potassium than did protein estimated simply as 27% of dual-energy X-ray absorptiometry fat-free mass minus total body mineral. 6. Hydration in patients with chronic renal failure in whom fluid balance is believed to be normal on clinical criteria does not differ from that in normal subjects. The combined model of dual-energy X-ray absorptiometry and total body water is not a useful method for the measurement of body protein.

Measurement of total body water by bioelectrical impedance in chronic renal failure

OBJECTIVE

Abnormalities of body hydration are common in patients with advanced chronic renal failure (CRF) and may be associated with important adverse clinical effects, even in the absence of clinical features of fluid retention or depletion. Bioelectrical impedance analysis (BIA) is a simple, non-invasive method of measuring body water content and thus could be of use in the management and study of patients with CRF. This study was performed to assess the ability of BIA to measure total body water (TBW) in patients with CRF.

DESIGN

TBW was measured by two different impedance systems, with comparison of the results with TBW determined by deuterium oxide dilution (D2O).

SETTING

Renal Unit, Leeds General Infirmary and Centre for Bone and Body Composition Research, University of Leeds, UK.

RESULTS

The range of the 95% limits of method agreement between BIA and D2O expressed as a percentage of the mean for the group was +/- 13.4% for the RJL 101A system and +/- 15.6% for the Holtain system in controls. For the whole CRF group the limits were moderately greater than controls at +/- 17.3% (RJL) and +/- 21.9% (Holtain). Analysis of subgroups of the CRF patients showed the smallest limits in those receiving peritoneal dialysis (+/- 15.5% RJL and 18.2% Holtain). Limits were greater for patients on haemodialysis (+/- 16.0% RJL and +/- 23.8% Holtain) and undialysed patients (+/- 20.1% and +/- 23.0%).

CONCLUSIONS

BIA is less accurate for the measurement of TBW in patients with CRF than in healthy subjects, though in some groups of patients the effect of CRF on the validity of this technique may be only mild. Abnormalities of reactance suggest that abnormal variability in the distribution of fluid between intra- and extracellular compartments is the major cause of reduced accuracy of TBW calculated by BIA in CRF patients.

The relationship between components of infant energy expenditure and childhood body fatness

OBJECTIVE

To investigate whether any component of infant energy expenditure is related to fatness in early childhood, and whether infant fatness is related to childhood variables.

DESIGN

Longitudinal investigation of infants studied at 12 weeks and followed up at 2.5 to 3.5 years of age.

SUBJECTS

30 healthy full-term infants selected from the general population.

MEASUREMENTS

Sleeping metabolic rate, total energy expenditure, anthropometry and behaviour at 12 weeks; anthropometry, body composition and behaviour in follow-up.

RESULTS

Energy expenditure at 12 weeks (minimal metabolism, total energy expenditure, energy expended on physical activity, behaviour) showed no relationship with later fatness. Infant fatness (skinfold thicknesses and percentage fat) showed in contrast a strong relationship with childhood fatness. Infant fatness also predicted childhood behaviour.

CONCLUSIONS

These data do not support the theory that reduced energy expenditure in early infancy is related to later fatness. However, infant fatness influences both later fatness and activity patterns.

Parental body composition and infant energy expenditure

It has been suggested that infants born to overweight parents are at risk of becoming overweight because of reduced total energy expenditure (TEE). We therefore examined the relationship between infant TEE and parental nutritional status as assessed by body mass index (BMI) in a large sample of healthy infants. TEE was measured by the doubly labeled water method in 124 infants at 12 wk of age. Sleeping metabolic rate (SMR) was measured by indirect calorimetry in 70 of these infants. Indexes of physical activity were calculated as TEE/SMR and TEE-SMR. No aspect of infant energy expenditure was found to be related to parental BMI. Moreover, there was no difference between TEE of two subsets of infants born to parents with high and low BMIs. We therefore find no evidence for parental body composition being associated with reduced infant energy expenditure at 12 wk of age.

Kinetic resolution of the reaction catalysed by proton-translocating transhydrogenase from Escherichia coli as revealed by experiments with analogues of the nucleotide substrates

The mechanism, by which transhydrogenase couples transfer of H- equivalents between NAD(H) and NADP(H) to the translocation of protons across a membrane, has been investigated in the solubilised, purified enzyme from Escherichia coli using analogues of the nucleotide substrates. The key observation was that, at low pH and ionic strength, solubilised transhydrogenase catalysed the very rapid reduction of acetylpyridine adenine dinucleotide (an analogue of NAD+) by NADH, but only in the presence of either NADP+ or NADPH. This indicates that the rates of release of NADP+ and NADPH from their binary complexes with the enzyme are slow. The dependences on pH and salt concentration suggest that (a) release of both NADP+ and NADPH are accompanied by the release of H+ from the enzyme and (b) increased ionic strength decreases the value of the pKa of the group responsible for H+ release. Modification of the enzyme with N,N1-dicyclohexylcarbodiimide led to inhibition of the rate of release of NADP+ and NADPH from the enzyme, but had a much smaller effect on the binding and release of NAD+, NADH and their analogues and on the interconversion of the ternary complexes of the enzyme with its substrates. It is considered that the binding and release of H+, which accompany the binding and release of NADP+/NADPH, might be central to the mechanism of proton translocation by the enzyme in its membrane-bound state.

Energy expenditure in children with congenital heart disease, before and after cardiac surgery

Failure to thrive is a common feature of children with congenital heart disease. Whether this is the result of poor nutrition or an abnormally high basal metabolic rate is unknown, yet the state of nutrition has a profound effect on the metabolic response to injury and strongly influences the outcome of surgical treatment. The aim of this study was therefore to measure the preoperative and postoperative energy requirements of children with congenital heart disease. Eighteen children (aged 4 to 33 months) were given two oral doses of doubly labeled water (H2(18)O and 2H2O), the first 1 week before operation and the second 6 hours after the end of cardiac surgery. By measuring the relative loss of each isotope from the body water pool, we were able to calculate the rate of carbon dioxide production and therefore total energy expenditure. In five patients, energy expenditure was clearly elevated, suggesting that a raised basal metabolic rate is an important factor in the observed failure to thrive in at least a proportion of such children. Postoperatively, energy expenditure fell to values below normal for healthy children (not having an operation), which suggests that the stress of surgery leads to smaller energy requirements than have previously been thought.