Effect of feed withdrawal on Campylobacter in the crops of market-age broiler chickens

The presence of Campylobacter and Salmonella on poultry meat products remains a significant public health concern. Previous research has indicated that feed withdrawal may significantly increase Salmonella contamination of broiler crops and that crop contents may serve as an important source of Salmonella carcass contamination at commercial processing. The present study evaluated the effect of preslaughter feed withdrawal on the incidence of Campylobacter isolation in crops of market-age commercial broiler chickens prior to capture and transport to the processing plant. The incidence of Campylobacter isolation from the crop was determined immediately before and after feed withdrawal in 40 7-wk-old broiler chickens obtained from each of nine separate broiler houses. Ceca were collected from broilers in six of the same flocks for comparison with the crop samples. Feed withdrawal caused a significant (P < 0.025) increase in Campylobacter-positive crop samples in seven of the nine houses sampled. Furthermore, the total number of Campylobacter-positive crops increased significantly (P < 0.001) from 90/360 (25%) before feed removal to 224/359 (62.4%) after the feed withdrawal period. Alternatively, feed withdrawal did not significantly alter the Campylobacter isolation frequency from ceca. Similar to our previous studies with Salmonella, the present results suggest that preharvest feed withdrawal increases the frequency of Campylobacter crop contamination and, thus, provides a source of Campylobacter contamination of carcasses at commercial processing.     

Rate of HIV-1 decline following antiretroviral therapy is related to viral load at baseline and drug regimen

OBJECTIVES AND DESIGN: The dynamics uf viral decline following the initiation of antiretroviral treatment were studied in 29 HIV-1-infected patients participating in a two-arm trial comparing immediate (group A: ritonavir, zidovudine and lamivudine) and delayed (group B: ritonavir supplemented by zidovudine and lamivudine on day 21) triple therapy. Parameters underlying viral dynamics were estimated using mathematical models tailored to these treatment protocols. RESULTS: The decline in plasma HIV-1 density between day 0 and 21 was steeper in group A (-2.27+/- 0.46 log10) than group B (-1.87+/-0.56 log10). In a subset of patients amenable to full mathematical analysis, a short-lived productively infected cell compartment (producing approximately 97% of total virions) decayed with a half-life of 1.0-2.5 days, whereas a long-lived infected cell compartment decayed with a half-life of 18.8-32.8 days. Estimates for the time for the elimination of virus from these two cell populations ranged from 474 to 802 days. The rate of loss of productively infected CD4+ T cells was positively correlated with baseline viral load in group A and in the combined dataset. CONCLUSIONS: These results suggest that HIV-infected cell populations may have a faster turnover in patients with higher viral loads due to higher infection rate parameters, higher rates of virus production, or lower virus clearance rates.     

Sequence alterations of insulin-like growth factor binding protein 3 in neoplastic and normal gastrointestinal tissues

Insulin-like growth factor binding protein 3 (IGFBP-3) is an important regulator of normal and malignant cell growth. It modulates the mitogenic effects of insulin-like growth factors (IGFs) by inhibiting growth through mechanisms both dependent on and independent of IGF binding. IGF-I and IGF-II levels are regulated by binding to the IGF-II receptor, which is inactivated by mutation in human gastrointestinal (GI) tumors. We have previously demonstrated elevated IGF-II ligand expression in IGF-II receptor-mutant GI tumors, implicating the IGF signaling system in GI tumorigenesis. Therefore, to investigate the potential involvement of IGFBP-3 in human GI carcinogenesis, direct DNA sequencing of exons 1-4 and intron-exon boundaries of the IGFBP-3 gene was performed in 10 colorectal cancers, 10 gastric cancers, and 10 esophageal cancers. Four distinct sequence alterations were identified: (a) in one gastric and one esophageal tumor, an A to C transversion occurred at nucleotide 5795 (CAC-->CCC), leading to a His-->Pro substitution at codon 179; (b) a second esophageal tumor had a C to T transition at nucleotide 8291 (ACC-->ATC), leading to a Thr-->Ile substitution at codon 277 of IGFBP-3; (c) one alteration comprised a G to C transversion in exon 1 at nucleotide 2132 (GGG-->GCG), leading to a Gly-->Ala substitution at codon 32 in two gastric cancers, seven esophageal cancers, and nine colon cancers; and (d) a C to G transversion located 17 nucleotides from the 3' splice site in intron 1 was observed in three colon cancers and four esophageal cancers. All of these DNA sequence alterations were present in matched normal DNA from the same subjects, which suggests that some or all of them may represent polymorphisms. However, we cannot exclude the possibility that the germ-line nonconservative amino acid substitutions predicted to occur as a result of these alterations result in subtle changes to IGFBP-3 protein function and a predisposition to developing GI malignancy.     

D1 and D2 dopamine receptor mediation of amphetamine-induced acetylcholine release in nucleus accumbens

To assess the interaction of dopamine and acetylcholine systems in the rat nucleus accumbens in response to direct D-amphetamine administration, in vivo microdialysis measures of acetylcholine were used during reverse dialysis of amphetamine alone and in combination with D1 and D2 receptor antagonists SCH 23390 and sulpiride, respectively. During a 15-min exposure to amphetamine (50 microM) in the nucleus accumbens, acetylcholine increased to 33% above pre-infusion levels, became maximal at 15 min post-infusion (+41%) and gradually returned to baseline levels by 60 min post-amphetamine. Conversely, amphetamine (1 mM) administration caused a biphasic change in acetylcholine release with a trend toward a decrease (-14%) during exposure followed by a significant increase (+36%) at 30 min post-amphetamine that returned to baseline levels by 60 min after infusion. The increases observed during amphetamine (50 microM) exposure and during recovery from amphetamine (1 mM) were both blocked by co-administration with the D1 antagonist, SCH 23390 (10 microM), but not with the D2 antagonist, sulpiride (10 microM). Co-infusion of sulpiride eliminated the trend toward reduced acetylcholine release observed during 1 mM amphetamine whereas co-administration of SCH 23390 potentiated this decrease. A possible tonic D1 facilitation of nucleus accumbens acetylcholine release was indicated by the consistent reductions in acetylcholine release observed during infusion of SCH 23390. These results suggest that amphetamine administration in the nucleus accumbens induces a bidirectional change in acetylcholine release that is dependent on dose and opposing effects of nucleus accumbens D1 and D2 activation. In general, relatively low doses of amphetamine administered into the nucleus accumbens caused an increase in acetylcholine release that was dependent on dopamine D1 receptors whereas higher doses of amphetamine resulted in a D2-mediated decrease.     

Active Wegener's granulomatosis is associated with HLA-DR+ CD4+ T cells exhibiting an unbalanced Th1-type T cell cytokine pattern: reversal with IL-10

Wegener's granulomatosis (WG) is a granulomatous vasculitis that affects the upper respiratory tract, lung, and kidney. Since T cells make up a significant proportion of cells infiltrating granulomatous lesions in WG, we investigated the proliferative response and cytokine profile of T cells from these patients. PBMCs were isolated from 12 patients with active WG, 7 patients with inactive disease, and 12 healthy normal donors. PBMCs from clinically active WG patients exhibited increased proliferation following stimulation with either PMA/ionomycin or anti-CD2 and anti-CD28, when compared with normal donors. In addition, these PBMCs exhibited increased secretion of IFN-gamma, but not of IL-4, IL-5, or IL-10. Furthermore, TNF-alpha production from PBMCs and CD4+ T cells isolated from patients with WG was elevated, when compared with healthy donors. In further studies, we investigated the ability of WG patients' monocytes to produce IL-12 and showed that both inactive and active patients produced increased amounts of IL-12. Finally, the in vitro IFN-gamma production by WG PBMC is inhibited in a dose-dependent manner by exogenous IL-10. These data suggest that T cells from WG patients overproduce IFN-gamma and TNF-alpha, probably due to dysregulated IL-12 secretion, and that IL-10 may therefore have therapeutic implications for this disease.     

Thymic alterations in feline GM1 gangliosidosis

GM1 gangliosidosis is an inherited metabolic disease characterized by progressive neurological deterioration with premature death seen in children and numerous animals, including cats. We have observed that thymuses from affected cats greater than seven months of age (GM1 mutant cats) show marked thymic reduction compared to age-matched normal cats. The studies reported here were done to describe alterations in the thymus prior to (less then 90 days of age) and during the development of mild (90 to 210 days of age) to severe (greater than 210 days of age) progressive neurologic disease and to explore the pathogenesis of the thymic abnormality. Although histologic examination of the thymus from GM1 affected cats less than 210 days of age showed no significant differences from age-matched control cats, thymuses from GM1 mutant cats greater than 210 days of age were significantly reduced in size (approximately 3-fold). Histologic sections of lymph nodes, adrenal glands, and spleens from GM1 gangliosidosis-affected cats showed no significant differences. Flow cytometric analyses showed a marked decrease in the percentage of immature CD4+CD8+ thymocytes (p < 0.001) and significantly increased CD4-CD8+ cells (p < 0.01) in GM1 mutant cats greater than 210 days of age when compared to normal age matched cats. Co-labelling with CD4, CD8, and CD5 indicated an increase in the percentage of GM1 mutant cat thymocytes at this age which were CD5high, suggesting the presence of more mature cells. Cytometric analyses of subpopulations of peripheral lymphocytes indicated an increase in CD4-CD8+ cells (p < 0.05) with concurrent decreases in CD4+CD8- and CD4-CD8- cells (which were not significant). Similar analyses of thymocyte and lymphocyte subpopulations from cats < 210 days of age showed no significant differences between GM1 mutant and normal cells. GM1 mutant cats at all ages had increased surface binding of Cholera toxin B on thymocytes, indicating increased surface GM1 ganglioside expression. Increases were highly significant in GM1 mutant cats greater than 210 days of age. In situ labelling for apoptosis was increased in GM1 mutant cats between 90 to 200 days of age when thymic masses were within normal limits. In GM1 mutant cats over 200 days of age, decreased labelling was observed when thymic mass was reduced and the CD4+CD8+ subpopulation, known to be very susceptible to apoptosis, was significantly decreased. These data describe premature thymic involution in feline GM1 gangliosidosis and suggest that increased surface GM1 gangliosides alters thymocyte development in these cats.     

Identification and characterization of the PutP proline permease that contributes to in vivo survival of Staphylococcus aureus in animal models

Staphylococcus aureus is an important pathogen of humans and other animals, causing bacteremia, abscesses, endocarditis, and other infectious syndromes. A signature-tagged mutagenesis (STM) system was adapted for use in studying the genes required for in vivo survival of S. aureus. An STM library was ultimately created in S. aureus RN6390, with Tn917 being used to create the transposon mutations. Pools of S. aureus RN6390 mutants were screened in mouse abscess, bacteremia, and wound infection models for growth attenuation after in vivo passage. One of the mutants that was identified displayed marked attenuation following large-pool screening in all three animal models, which was confirmed in bacteremia and endocarditis models of infection with a smaller pool of mutants. Sequence analysis of the entire open reading frame showed a 99% identity to the high-affinity proline permease (putP) gene characterized in another strain of S. aureus. In wound and murine abscess infection models, the putP mutant was approximately 10-fold more attenuated than was wild-type strain RN6390. Another S. aureus strain transduced with the putP mutation also displayed an attenuated phenotype after passage in the wound model. A [3H]proline uptake assay showed that less proline was specifically transported into the putP mutant than into strain RN6390. The reduced viability of the bacteria possessing the mutation in the S. aureus high-affinity proline permease suggests that proline scavenging by the bacteria is important for in vivo growth and proliferation and that analogs of proline may serve as potential antistaphylococcal therapeutic agents.     

Promethean thymus?

We report the case of a 57-yr-old woman presenting with moderate weight loss, abdominal distension, and lymphedema of the legs and vulva. Computed tomography of the abdomen revealed massive thickening of the rectal wall, mesentery, and retroperitoneum. Primary amyloidosis was diagnosed by immunohistochemistry from the rectum and duodenum. To our knowledge, lymphedema due to primary amyloidosis has not yet been reported. The diagnosis should be presumed in the case of retroperitoneal thickening and lymphedema and can be established by immunohistochemistry.