24-hour changes in circulating prolactin, follicle-stimulating hormone, luteinizing hormone, and testosterone in young male rats subjected to calorie restriction

This work analyzes the effect of calorie restriction on the 24 h variation of pituitary-testicular function in young male Wistar rats by measuring the circulating levels of prolactin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone. Control animals were provided an equilibrium calorie diet and the experimental animals a calorie-restriction diet equivalent to 66% of food restriction for four weeks starting on day 35 of life. Different groups of control and experimental rats were killed at 6 h intervals around the clock, beginning 1 h after light on (HALO). Compared to the control animals, the mean secretion of prolactin was augmented and that of LH and testosterone decreased in calorie-restricted rats, whereas FSH release remained unchanged. Significant changes in the 24 h secretory pattern of circulating prolactin, LH, and testosterone occurred in the calorie-restricted rats. These include the appearance of a second maximum of plasma prolactin at 21 HALO, blunting of the LH peak seen at 13 HALO, and phase-shift of the testosterone peak from 13 HALO in controls to 17 HALO in calorie-restricted rats. The significant positive correlation between individual LH and testosterone levels found in controls was no longer observed in calorie-restricted rats. Availability of nutrients presumably affects the mechanisms that modulate the circadian variation of the pituitary-gonadal axis in growing male rats.     

CD4+/CD25+ regulatory cells inhibit activation of tumor-primed CD4+ T cells with IFN-gamma-dependent antiangiogenic activity, as well as long-lasting tumor immunity elicited by peptide vaccination

CD25(+) regulatory T (T reg) cells suppress the activation/proliferation of other CD4(+) or CD8(+) T cells in vitro. Also, down-regulation of CD25(+) T reg cells enhance antitumor immune responses. In this study, we show that depletion of CD25(+) T reg cells allows the host to induce both CD4(+) and CD8(+) antitumoral responses following tumor challenge. Simultaneous depletion of CD25(+) and CD8(+) cells, as well as adoptive transfer experiments, revealed that tumor-specific CD4(+) T cells, which emerged in the absence of CD25(+) T reg cells, were able to reject CT26 colon cancer cells, a MHC class II-negative tumor. The antitumoral effect mediated by CD4(+) T cells was dependent on IFN-gamma production, which exerted a potent antiangiogenic activity. The capacity of the host to mount this antitumor response is lost once the number of CD25(+) T reg cells is restored over time. However, CD25(+) T reg cell depletion before immunization with AH1 (a cytotoxic T cell determinant from CT26 tumor cells) permits the induction of a long-lasting antitumoral immune response, not observed if immunization is conducted in the presence of regulatory cells. A study of the effect of different levels of depletion of CD25(+) T reg cells before immunization with the peptide AH1 alone, or in combination with a Th determinant, unraveled that Th cells play an important role in overcoming the suppressive effect of CD25(+) T reg on the induction of long-lasting cellular immune responses.     

SAR studies of epoxycurcuphenol derivatives on leukemia CT-CD4 cells

Bioactive natural products are a potential source of new pharmaceuticals since they offer new modes of action and more specific activities. The use of derivatization also enables the optimal structure for their biological activity to be determined. In this study several epoxycurcuphenol derivatives were synthesized. The substitution pattern on the aromatic and oxirane rings was varied along with that at the benzylic position and the length of the side chain was altered. These changes were made in order to gain a deeper understanding of the structural requirements for activity. The biological activities of these compounds were evaluated on the human leukemia cell line Jurkat using an antiproliferative assay. The activity results and structural requirements are discussed.     

Low-grade inflammation and the metabolic syndrome in children and adolescents

PURPOSE OF REVIEW: The prevalence of overweight and the metabolic syndrome is increasing in young people. This review aims to summarize current research in children and adolescents on inflammatory markers related to components of the metabolic syndrome. RECENT FINDINGS: Obesity is characterized by a state of low-grade inflammation at all ages. Body fat has been shown to correlate with the various components of the metabolic syndrome. There is evidence to show that chronic subclinical inflammation in childhood and adolescence is associated with metabolic dysfunction, which can lead to insulin resistance and the metabolic syndrome. SUMMARY: The results presented in this review highlight the underlying inflammatory mechanisms of the early stages of metabolic disorders related to obesity. The preclinical phases of diabetes and cardiovascular disease last many decades, and this feature of the diseases provides an opportunity for the early identification of target groups and the use of appropriate prevention strategies while the pathological processes are still completely reversible.     

The arbuscular mycorrhizal fungus Rhizophagus irregularis uses a reductive iron assimilation pathway for high‐affinity iron uptake

Arbuscular mycorrhizal (AM) fungi can improve iron (Fe) acquisition of their host plants. Here, we report a characterization of two components of the high‐affinity reductive Fe uptake system of Rhizophagus irregularis, the ferric reductase (RiFRE1) and the high affinity Fe permeases (RiFTR1‐2). In the extraradical mycelia (ERM), Fe deficiency induced activation of a plasma membrane‐localized ferric reductase, an enzyme that reduces Fe(III) sources to the more soluble Fe(II). Yeast mutant complementation assays showed that RiFRE1 encodes a functional ferric reductase and RiFTR1 an iron permease. In the heterologous system, RiFTR1 was expressed in the plasma membrane while RiFTR2 was expressed in the endomembranes. In the ERM, the highest expression levels of RiFTR1 were found in mycelia grown in media with 0.045 mM Fe, while RiFTR2 was upregulated under Fe‐deficient conditions. RiFTR2 expression also increased in the intraradical mycelia (IRM) of maize plants grown without Fe. These data indicate that the Fe permease RiFTR1 plays a key role in Fe acquisition and that RiFTR2 is involved in Fe homeostasis under Fe‐limiting conditions. RiFTR1 was highly expressed in the (IRM), which suggests that the maintenance of Fe homeostasis in the IRM might be essential for a successful symbiosis.     

Influence of environmental and genetic factors linked to celiac disease risk on infant gut colonization by Bacteroides species

Celiac disease (CD) is an immune-mediated enteropathy involving genetic and environmental factors whose interaction might influence disease risk. The aim of this study was to determine the effects of milk-feeding practices and the HLA-DQ genotype on intestinal colonization of Bacteroides species in infants at risk of CD development. This study included 75 full-term newborns with at least one first-degree relative suffering from CD. Infants were classified according to milk-feeding practice (breast-feeding or formula feeding) and HLA-DQ genotype (high or low genetic risk). Stools were analyzed at 7 days, 1 month, and 4 months by PCR and denaturing gradient gel electrophoresis (DGGE). The Bacteroides species diversity index was higher in formula-fed infants than in breast-fed infants. Breast-fed infants showed a higher prevalence of Bacteroides uniformis at 1 and 4 months of age, while formula-fed infants had a higher prevalence of B. intestinalis at all sampling times, of B. caccae at 7 days and 4 months, and of B. plebeius at 4 months. Infants with high genetic risk showed a higher prevalence of B. vulgatus, while those with low genetic risk showed a higher prevalence of B. ovatus, B. plebeius, and B. uniformis. Among breast-fed infants, the prevalence of B. uniformis was higher in those with low genetic risk than in those with high genetic risk. Among formula-fed infants, the prevalence of B. ovatus and B. plebeius was increased in those with low genetic risk, while the prevalence of B. vulgatus was higher in those with high genetic risk. The results indicate that both the type of milk feeding and the HLA-DQ genotype influence the colonization process of Bacteroides species, and possibly the disease risk.     

Single-step, multiple retroviral transduction of human T cells

Background

Retroviral transduction of human peripheral blood T cells has considerable potential in the development of gene therapy strategies for immunological disorders. New vectors and experimental procedures have been developed for efficient transduction of several genes into human T cells.

Methods

Bicistronic retroviral vectors encoding distinct cell markers were used for the simultaneous multiple transduction of a human T‐cell line (MT‐2), as well as of human peripheral blood T cells from normal donors. Transduction efficiencies were evaluated by flow cytometry and double‐ and triple‐transduced cells were isolated by fluorescence cell sorting.

Results

Four new bicistronic retroviral vectors were developed that express different gene markers under the control of the internal ribosome entry site (IRES) of the encephalomyocarditis virus. These markers are, respectively, enhanced green fluorescent protein (EGFP), β‐galactosidase, and truncated versions of human nerve growth factor receptor (ΔNGFR) and human growth hormone receptor (ΔGHR). A single 1 h spinoculation infection, performed in the presence of polybrene and using transiently produced amphotropic retroviral particles, was sufficient to obtain transduction efficiencies consistently greater than 50% on human peripheral blood T lymphocytes which had been previously stimulated for 3 days with immobilized anti‐CD3. The transient production of viral particles encoding EGFP, ΔNGFR, and ΔGHR markers in the same viral supernatant has allowed up to three different genes to be introduced simultaneously into human T cells.

Conclusions

This study describes new experimental conditions for efficient single‐step multiple transduction of human primary T lymphocytes. The procedure could be of interest for the development of gene therapy approaches. Copyright © 2002 John Wiley & Sons, Ltd.