Offspring from mothers fed a 'junk food' diet in pregnancy and lactation exhibit exacerbated adiposity that is more pronounced in females.

We have shown previously that a maternal junk food diet during pregnancy and lactation plays a role in predisposing offspring to obesity. Here we show that rat offspring born to mothers fed the same junk food diet rich in fat, sugar and salt develop exacerbated adiposity accompanied by raised circulating glucose, insulin, triglyceride and/or cholesterol by the end of adolescence (10 weeks postpartum) compared with offspring also given free access to junk food from weaning but whose mothers were exclusively fed a balanced chow diet in pregnancy and lactation. Results also showed that offspring from mothers fed the junk food diet in pregnancy and lactation, and which were then switched to a balanced chow diet from weaning, exhibited increased perirenal fat pad mass relative to body weight and adipocyte hypertrophy compared with offspring which were never exposed to the junk food diet. This study shows that the increased adiposity was more enhanced in female than male offspring and gene expression analyses showed raised insulin-like growth factor-1 (IGF-1), insulin receptor substrate (IRS)-1, vascular endothelial growth factor (VEGF)-A, peroxisome proliferator-activated receptor-gamma (PPARgamma), leptin, adiponectin, adipsin, lipoprotein lipase (LPL), Glut 1, Glut 3, but not Glut 4 mRNA expression in females fed the junk food diet throughout the study compared with females never given access to junk food. Changes in gene expression were not as marked in male offspring with only IRS-1, VEGF-A, Glut 4 and LPL being up-regulated in those fed the junk food diet throughout the study compared with males never given access to junk food. This study therefore shows that a maternal junk food diet promotes adiposity in offspring and the earlier onset of hyperglycemia, hyperinsulinemia and/or hyperlipidemia. Male and female offspring also display a different metabolic, cellular and molecular response to junk-food-diet-induced adiposity.

Neuromuscular stimulation causes muscle phenotype-dependent changes in the expression of the IGFs and their binding proteins in developing slow and fast muscle of chick embryos.

Insulin-like growth factor (IGF) -1 and -2 and binding protein (IGFBP-2, -4, and -5) expression can be affected by several environmental factors, but the impact of movement on the IGF axis during late embryogenesis has yet to be fully characterized. Movement was promoted in chick embryos during mid-embryogenesis using 4-aminopyridine (4-AP). The results indicate an increase in IGF-1 (P < 0.01) and a decrease in IGFBP-2 (P < 0.05) mRNA expression in slow muscle of the stimulated group compared with the control group. In fast muscle, there was a decrease in IGF-2 (P < 0.01) on embryonic day (ED) 16 and an increase in IGFBP-2 (P < 0.01) and IGFBP-4 (P < 0.05) and in IGFBP-5 (P < 0.05) expression on ED18 in the stimulated group compared with the control group. These results indicate that neuromuscular stimulation with 4-AP influences IGF axis gene expression in a muscle fiber type-dependent manner. Consequences of the changes in the IGF system for each muscle are discussed.

The pCS20 PCR assay for Ehrlichia ruminantium does not cross-react with the novel deer ehrlichial agent found in white-tailed deer in the United States of America.

White-tailed deer are susceptible to heartwater (Ehrlichia [Cowdria] ruminantium infection) and are likely to suffer high mortality if the disease spreads to the United States. It is vital, therefore, to validate a highly specific and sensitive detection method for E. ruminantium infection that can be reliably used in testing white-tailed deer, which are reservoirs of antigenically or genetically related agents such as Ehrlichia chaffeensis, Anaplasma (Ehrlichia) phagocytophilum (HGE agent) and Ehrlichia ewingii. Recently, a novel but as yet unnamed ehrlichial species, the white-tailed deer ehrlichia (WTDE), has been discovered in deer populations in the United States. Although the significance of WTDE as a pathogen is unknown at present, it can be distinguished from other Ehrlichia spp. based on 16S rRNA gene sequence analysis. In this study it was differentiated from E. ruminantium by the use of the pCS20 PCR assay which has high specificity and sensitivity for the detection of E. ruminantium. This assay did not amplify DNA from the WTDE DNA samples isolated from deer resident in Florida, Georgia and Missouri, but amplified the specific 279 bp fragment from E. ruminantium DNA. The specificity of the pCS20 PCR assay for E. ruminantium was confirmed by Southern hybridization. Similarly, the 16S PCR primers (nested) that amplify a specific 405-412 bp fragment from the WTDE DNA samples, did not amplify any product from E. ruminantium DNA. This result demonstrates that it would be possible to differentiate between E. ruminantium and the novel WTDE agent found in white tailed deer by applying the two respective PCR assays followed by Southern hybridizations. Since the pCS20 PCR assay also does not amplify any DNA products from E. chaffeensis or Ehrlichia canis DNA, it is therefore the method of choice for the detection of E. ruminantium in these deer and other animal hosts.

Comparing the detection of exposure to Ehrlichia ruminantium infection on a heartwater-endemic farm by the pCS20 polymerase chain reaction assay and an indirect MAP1-B enzyme linked immunosorbent assay.

Detection of heartwater is not always easy especially because all the serological assays so far available either have poor sensitivity or specificity. The indirect MAP-1B ELISA has been reported to be the most specific test for heartwater, although it does also detect antibodies to some closely related ehrlichial agents. This study was undertaken to compare two methods for the detection of heartwater infection caused by the ehrlichial agent Ehrlichia (Cowdria) ruminantium. Fifteen cattle on a heartwater-endemic farm infested with high numbers of Amblyomma hebraeum ticks, and hence exposure to E. ruminantium infection were monitored over an 8-week period by pCS20 PCR and an indirect MAP-1B ELISA. Infection was detected by pCS20 PCR in most animals with the highest number of positives (60%) in week 6 of the study. Similarly, exposure to E. ruminantium was detected by indirect MAP-1B ELISA in some animals, with the highest number of seropositives (27%) at weeks 2-6 of the study. The data demonstrated a fluctuating rickettsaemia in cattle in a heartwater-endemic area. Comparison of the two tests indicated that the pCS20 PCR assay was more reliable because it detected more infections than the indirect MAP-1B ELISA and would therefore be the method of choice for detection of E. ruminantium infection.

Introduction of the exotic tick Amblyomma hebraeum into Florida on a human host.

A resident of Florida returned from a short visit to southern Africa to find a male Amblyomma hebraeum tick attached to the skin behind her knee. Amblyomma hebraeum is a major vector of 2 pathogens that cause important diseases in southern Africa, heartwater of ruminants and African tick-bite fever of humans. The tick was tested by polymerase chain reaction assay for evidence of infection with Cowdria ruminantium and Rickettsia africae (the causative agents of heart-water and African tick-bite fever, respectively) and was found to be negative for both agents. This is the second record of the exotic tick, A. hebraeum, being introduced into the United States on a human host.

The prevalence of Cowdria ruminantium in free-living adult Amblyomma hebraeum collected at a communal grazing area and in 2 wildlife reserves in South Africa.

In order to detect the prevalence of Cowdria ruminantium in the vector tick, Amblyomma hebraeum, free-living, unfed adult ticks were collected with the aid of pheromone/CO2 traps. Ticks were collected at the Rietgat communal grazing area, as well as in the southwestern Kruger National Park and in the Songimvelo Game Reserve, all located in heartwater-endemic areas of South Africa. The presence of C. ruminantium in these ticks was determined by polymerase chain reaction (PCR) analysis. Ticks from the Rietgat communal grazing area were assayed in 2 batches and 4.7% of the one and 11.3% of the other were positive for infection, while 5.7% of the ticks collected in the Kruger National Park and 25% in the Songimvelo Game Reserve were positive. These results support the contention that a vector-wildlife cycle of transmission of C. ruminantium, the cause of heartwater in domestic ruminants, can be maintained in the absence of the latter animals.

A subset of Cowdria ruminantium genes important for immune recognition and protection.

Cowdria ruminantium causes the tick-borne rickettsial disease of heartwater, which is devastating to livestock production in sub-Saharan Africa. Current diagnosis and control methods are inadequate. We have identified and sequenced a subset of genes encoding recombinant antigens recognized by antibody and peripheral blood mononuclear cells from immune ruminants. The identified genes include many with significant similarity to those of Rickettsia prowazekii, genes predicted to encode different outer membrane proteins and lipoproteins and a gene containing an unusual tandem repeat structure. Evidence is presented for immune protection by recombinant antigens in a mouse model of C. ruminantium infection. These data identify new recombinant antigens for evaluation in vaccines and diagnostic tests to control heartwater.

Evidence of Cowdria ruminantium infection (heartwater) in Amblyomma sparsum ticks found on tortoises imported into Florida.

Amblyomma marmoreum and A. sparsum ticks were collected from tortoises imported into Florida from Africa and were tested for Cowdria ruminantium infection using a C. ruminantium-specific pCS20 polymerase chain reaction assay. In I shipment imported from Zambia, 15 of the 38 A. sparsum male ticks collected from the leopard tortoises (Geochelone pardalis) were found to be positive for infection with C. ruminantium. In contrast, all 148 A. marmoreum tested were negative for C. ruminantium infection. This is the first reported evidence of the introduction of heartwater-infected ticks into the United States, but there were no opportunities to confirm isolation of C. ruminantium from the ticks by either culture or transmission studies.

Detection of the agent of heartwater, Cowdria ruminantium, in Amblyomma ticks by PCR: validation and application of the assay to field ticks.

We have previously reported that the pCS20 PCR detection assay for Cowdria ruminantium, the causative agent of heartwater disease of ruminants, is more sensitive than xenodiagnosis and the pCS20 DNA probe for the detection of infection in the vector Amblyomma ticks. Here, we further assessed the reliability of the PCR assay and applied it to field ticks. The assay detected DNA of 37 isolates of C. ruminantium originating from sites throughout the distribution of heartwater and had a specificity of 98% when infected ticks were processed concurrently with uninfected ticks. The assay did not detect DNA of Ehrlichia chaffeensis, which is closely related to C. ruminantium. PCR sensitivity varied with tick infection intensity and was high (97 to 88%) with ticks bearing 10(7) to 10(4) organisms but dropped to 61 and 28%, respectively, with ticks bearing 10(3) and 10(2) organisms. The assay also detected C. ruminantium in collections of Amblyomma hebraeum and Amblyomma variegatum field ticks from 17 heartwater-endemic sites in four southern African countries. Attempts at tick transmission of infection to small ruminants failed with four of these collections. The pCS20 PCR assay is presently the most characterized and reliable test for C. ruminantium in ticks and thus is highly useful for field and laboratory epidemiological investigations of heartwater.

Comparison of efficacy of American and African Amblyomma ticks as vectors of heartwater (Cowdria ruminantium) infection by molecular analyses and transmission trials.

The ability of Amblyomma americanum, Amblyomma cajennense, Amblyomma maculatum, and Amblyomma variegatum to acquire and transmit Cowdria ruminantium infection was investigated. Uninfected nymphs were fed on clinically reacting C. ruminantium-infected sheep and then analyzed for infection by specific DNA detection assays and by tick transmission trials. By polymerase chain reaction (PCR), the mean infection prevalence of A. maculatum ticks (50.7%) was similar to that of A. variegatum, Elevage strain (43.5%; P = 0.83) and Petit Bourg strain (45.9%; P = 0.26) ticks. Though Amblyomma hebraeum were not tested by PCR, by DNA probe their infection prevalence was 94%. In contrast, A. americanum and A. cajennense ticks demonstrated very low susceptibility to C. ruminantium, and the prevalence of infection by PCR was approximately 1%. The higher susceptibility of A. maculatum and A. variegatum to C. ruminantium correlated with superior vector efficiency, depicted by similar prepatent periods and severity of disease transmissions to sheep. Amblyomma americanum and A. cajennense failed to transmit infection, confirming that low susceptibility to C. ruminantium correlates with the poor vector status of these species. These results highlight the importance of A. maculatum as a potential vector that is likely to play a major role in the establishment and maintenance of heartwater, if the disease were to be introduced to the U.S.A., Central, and South America.

PCR detection of Cowdria ruminantium infection in ticks and animals from heartwater-endemic regions of Zimbabwe.

The development of a PCR assay for the detection of Cowdria ruminantium infection in ticks has been previously described. Here we report a further evaluation of this assay by comparison with a DNA probe and with the mouse inoculation assay (MIA). Application of the PCR assay in determining the prevalence of infection in ruminants and ticks from heartwater-endemic areas of Zimbabwe is also described. One hundred uninfected and 120 infected Amblyomma hebraeum ticks were analyzed by PCR, DNA probe and the MIA. These tests detected infection in 92%, 77% and 8% of the infected ticks, respectively, showing PCR to be the most sensitive assay. None of the uninfected ticks were positive by any of the 3 tests. The PCR assay detected infection rates of 10.5%, 12.5% and 3.2% in 200 male, 241 female and 95 nymphal A. hebraeum ticks, respectively, which were collected from a heartwater-endemic farm. The PCR test was also applied to cattle of different age groups and goats from the same heartwater-endemic farm. In a cross-sectional survey, the assay detected infection in 3.3% to 26.7% of the cattle and in 23.3% of the goats. The implications of these findings and the potential for the application of PCR in heartwater diagnosis is discussed.

Laboratory reared Amblyomma hebraeum and Amblyomma variegatum ticks differ in their susceptibility to infection with Cowdria ruminantium.

The susceptibility of laboratory reared Zimbabwean Amblyomma hebraeum and A. variegatum ticks to infection with geographically distinct Cowdria ruminantium strains was investigated by feeding both species simultaneously on individual sheep infected with one of the four strains (Crystal Springs [Zimbabwe], Ball 3 [South Africa], Gardel [Guadeloupe] and Nigeria [Nigeria]). A. hebraeum ticks demonstrated a high susceptibility to infection with all four C. ruminantium strains. In comparison, A. variegatum were less susceptible to infection with the Crystal Springs and Ball 3 strains (P < 0.001), but showed a similar susceptibility to the Gardel and Nigeria strains. The differences in susceptibility of A. variegatum to infection with the four strains of C. ruminantium correlated with the origin of these strains. The consistently higher susceptibility of A. hebraeum ticks to infection with geographically different C. ruminantium strains may be one explanation for the observation that heartwater is a more serious problem where A. hebraeum is the vector of the disease.

Development and evaluation of PCR assay for detection of low levels of Cowdria ruminantium infection in Amblyomma ticks not detected by DNA probe.

The sensitivities of a PCR assay and a DNA probe assay were compared for the detection of Cowdria ruminantium in Amblyomma ticks that were fed on C. ruminantium-infected, clinically reacting, and recovered carrier animals. The PCR assay and DNA probe detected infection in 86.0 and 37.0%, respectively, of 100 ticks fed on a febrile animal. In 75 ticks fed on carrier animals, PCR and the DNA probe detected infection in 28.0 and 1.33% of ticks, respectively. This demonstrates that the DNA probe has poor sensitivity for the detection of low levels of infection in ticks and that PCR is necessary for this purpose. The PCR assay had a detection limit of between 1 and 10 C. ruminantium organisms and did not amplify DNA from Ehrlichia canis, which is phylogenetically closely related to C. ruminantium, Theileria parva, or uninfected Amblyomma hebraeum or A. variegatum. PCR detected infection in A. hebraeum and A. variegatum adult ticks infected with one of six geographically different C. ruminantium strains. Amplification was also possible from desiccated ticks and ticks fixed in 70% ethanol, 10% buffered formalin, or 2% glutaraldehyde. The PCR assay supersedes the DNA probe and older detection methods for the detection of C. ruminantium in ticks, particularly those fed on carrier animals, and is suitable for both prospective and retrospective studies which require accurate detection of C. ruminantium in individual ticks. Application of the PCR assay should significantly improve the understanding of heartwater epidemiology, particularly through the determination of field tick infection rates.