Caridad Leal

Influence of cytokine and intercellular adhesion molecule-1 gene polymorphisms on acute rejection in pediatric renal transplantation

Abstract:  Immune response regulation by cytokines is a key to understanding AGR. The influence of the functional polymorphisms in genes coding for TNF‐α (−308G > A), IL‐10 (−819C > T, and −1082A > G), IFN‐γ [(CA)n], TGF‐β1 (+869T > C), and iCAM‐1 (R241G and E469K), in addition to HLA and gender matching on the presentation of AGR in 51 pediatric renal recipients during a 36‐month post‐transplantation follow‐up were analyzed. Also, donors and a control group were genotyped. All groups were within Hardy‐Weinberg equilibrium for all polymorphisms except IL‐10–819C > T and TNF‐α (p < 0.005 and p < 0.01, respectively) in recipients. Transplants with gender mismatch showed a higher risk for AGR than those between individuals with gender match (OR, 4.227; p = 0.010). Recipients with a high‐production compared with low‐production TNF‐α allele experienced earlier AGR (p = 0.030), and those with high‐production alleles of both TNF‐α and IFN‐γ showed a further increased risk (OR = 11.129, p = 0.024). These findings support the notion that a single genotype cannot by itself explain an event as complex as AGR. The sum or combination of different specific alleles of these genes could better account for the immune response to an allograft.

Nitric oxide in the hypothalamus–pituitary axis mediates increases in brain glucose retention induced by carotid chemoreceptor stimulation with cyanide in rats

Neuronal nitric oxide synthase (nNOS), which catalyzes the generation of nitric oxide (NO), is expressed by neuron subpopulations in the CNS. Nitric oxide is involved in neurotransmission and central glucose homeostasis. Our prior studies have shown that carotid body receptors participate in brain glucose regulation in vivo, and suggest the presence of a NO tonic mechanism in the solitary tract nucleus (STn). However, the role of NO within STn in glucose control remains unknown. In this study, we explored the potential regulatory role of NO on brain glucose retention induced by carotid body chemoreceptor anoxic stimulation with sodium cyanide (NaCN) which inhibits oxidative metabolism. Intracisternal infusions of nitroxidergic drugs before carotid chemoreceptor stimulation in anesthetized rats, elicited changes in nitrite concentration in plasma and hypothalamus-pituitary (H-P) tissue, as well as in gene expression of neuronal and inducible isoforms (nNOS and iNOS) in H-P tissue. The changes observed in above variables modified brain glucose retention in an opposite direction. When the NO donor, sodium nitroprusside (SNP), was given before carotid stimulation, nitrite concentration in plasma and H-P tissue, and gene expression of nNOS and iNOS in H-P tissue increased, whereas brain glucose retention decreased. In contrast, when the NOS inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME) was infused immediately before carotid chemoreceptor stimulation, nitrite levels and nNOS expression decreased in plasma and H-P tissue, whereas brain glucose retention increased. Anoxic stimulation by itself induced an increase in the expression of both genes studied. All these results indicate that de novo expression of the nNOS gene in H-P tissue may be critically involved in central glucose changes observed after anoxic carotid chemoreceptor stimulation in conjunction with NO.

Nitric oxide in the commissural nucleus tractus solitarii regulates carotid chemoreception hyperglycemic reflex and c-Fos expression

Carotid body chemoreceptors function as glucose sensors and contribute to glucose homeostasis. The nucleus tractus solitarii (NTS) is the first central nervous system (CNS) nuclei for processing of information arising in the carotid body. Here, we microinjected a nitric oxide (NO) donor sodium nitroprusside (SNP), an NO-independent activator of the soluble guanylyl cyclase (sGC) (YC₁) or an NO-synthase (NOS) inhibitor Nω-nitro-l-arginine methyl ester (L-NAME) into the commissural NTS (cNTS) before carotid chemoreceptor anoxic stimulation and measured arterial glucose and the expression of Fos-like immunoreactivity (Fos-ir). Male Wistar rats (250-300 g) were anesthetized, and the carotid sinus was vascularly isolated. Either artificial cerebrospinal fluid (aCSF), SNP, YC₁ or L-NAME were stereotaxically injected into the cNTS. The SNP and YC₁ infused into the cNTS before carotid chemoreceptor stimulation (SNP-2 and YC₁-2 groups) similarly increased arterial glucose compared to the aCSF-2 group. By contrast, infusion of L-NAME into the cNTS before carotid chemoreceptor stimulation (L-NAME-2 group) decreased arterial glucose concentration. The number of cNTS Fos-ir neurons, determined in all the groups studied except for YC₁ groups, significantly increased in SNP-2 rat when compared to the aCSF-2 or SNP-2 groups. Our findings demonstrate that NO signaling, and the correlative activation of groups of cNTS neurons, plays key roles in the hyperglycemic reflex initiated by carotid chemoreceptor stimulation.

Nitric oxide infused in the solitary tract nucleus blocks brain glucose retention induced by carotid chemoreceptor stimulation

Previous work has shown that the carotid body glomus cells can function as glucose sensors. The activation of these chemoreceptors, and of its afferent nucleus in the brainstem (solitary tract nucleus - STn), induces rapid changes in blood glucose levels and brain glucose retention. Nitric oxide (NO) in STn has been suggested to play a key role in the processing of baroreceptor signaling initiated in the carotid sinus. However, the relationship between changes in NO in STn and carotid body induced glycemic changes has not been studied. Here we investigated in anesthetized rats how changes in brain glucose retention, induced by the local stimulation of carotid body chemoreceptors with sodium cyanide (NaCN), were affected by modulation of NO levels in STn. We found that NO donor sodium nitroprusside (SNP) micro-injected into STn completely blocked the brain glucose retention reflex induced by NaCN chemoreceptor stimulation. In contrast, NOS inhibitor N(ω)-nitro-L-arginine methyl ester (L-NAME) increased brain glucose retention reflex compared to controls or to SNP rats. Interestingly, carotid body stimulation doubled the expression of nNOS in STn, but had no effect in iNOS. NO in STn could function to terminate brain glucose retention induced by carotid body stimulation. The work indicates that NO and STn play key roles in the regulation of brain glucose retention.

del(X)(p22.1)/r(X)(p22.1q28) Dynamic mosaicism in a Turner syndrome patient.

We report on a 16-year-old patient with Turner syndrome who presented a mos 46,X,del(X)(p22.1)[35]/45,X [19]/46,X,r(X)(p22.1q28)[6]GTG-band karyotype. The R-banding showed that the abnormal X-chromosome was inactive in all 61 cells analyzed. Fluorescence in situ hybridization with a Xp/Yp subtelomeric probe revealed that both abnormal chromosomes lacked the complementary sequences, a fact consistent with a terminal deletion. Besides, the molecular analysis of the human androgen receptor gene showed that the rearranged chromosome was paternal in origin. Since the deleted and the ring chromosomes had the same size and banding pattern, and because the former was the predominant cell line, it was inferred that the Xp- formed a ring in some cells apparently without further loss of genetic material. However, the reverse sequence and even a simultaneous origin due to a complex intrachromosomal exchange are also conceivable. The mild Turner syndrome phenotype is explained by the mosaicism and by the size of the deleted segment.

Concomitant Effects of Nitric Oxide and Carotid Chemoreceptor Stimulation on Brain Glucose in Normoglycemic and Hyperglycemic Rats

BACKGROUND AND AIMS Carotid body (CB) sinus perfusion with different glucose concentrations modifies arterial glucose concentration and brain glucose retention, thereby changing the brains threshold to hypoxia. Because nitric oxide (NO) modulates hypoxic chemoreception, we investigated the relationship between NO- and CB-receptor pathways on arterial glucose and brain arteriovenous (a-v) glucose difference after hypoxic stimulation under hyperglycemic conditions. METHODS Normoglycemic and streptozotocin (STZ, 50 mg/kg i.p.)-induced hyperglycemic Sprague Dawley rats were infused with the NO donor, sodium nitroprusside (SNP), or the NOS inhibitor, Nω-nitro-L-arginine methyl ester (L-NAME) into the circulatory isolated carotid sinus after (30 sec) local anoxic CB chemoreceptor stimulation with sodium cyanide (NaCN). RESULTS L-NAME abolished the hyperglycemia and the increase in brain a-v glucose concentration difference induced by CB chemoreceptor stimulation in normoglycemic rats, whereas the same treatment in hyperglycemic rats did not change the glucose variables studied. However, SNP infused under the same conditions induced a bigger rise in arterial glucose and brain a-v glucose concentration difference only in normoglycemic rats, when compared with the results obtained in sham-2-control rats. CB stimulation plus SNP treatment also resulted in an increase in nitrite levels in cephalic venous blood in normoglycemic, but not in hyperglycemic, rats. CONCLUSIONS We showed a clear concomitant effect of SNP infusion into local CB circulation and anoxic cyanide stimulation, enhancing hyperglycemia and brain a-v glucose concentration difference. Importantly, at high glucose levels, nitrergic drugs did not modify glucose variables when compared with the corresponding sham controls.

Analysis of cytokine gene polymorphisms in Mestizo and native populations from Mexico

To determine whether the well‐known genetic structure of the Mexican population observed with other multiallelic markers can be detected by analyzing functional polymorphisms of cytokine and other inflammatory‐response‐related genes.

Apparent Neotelomere in a 46,X,del(X)(qter→p11.2:)/46,X,rea(X)(qter→p11.2::q21.2→qter) Novel Mosaicism: Review of 34 Females with a Recombinant-Like dup(Xq) Chromosome

A 26-year-old woman with secondary amenorrhea and turneroid stigmata was found to have a 46,X,rea(X)(qter→p11.2::q21.2→qter)/46,X,del(X)(qter→p11.2:) mosaicism in 101 G-banded metaphases (71 and 30, respectively). The mothers karyotype was normal (the father was already deceased). A fully skewed inactivation of both abnormal X-chromosomes was documented in RBG-banded metaphases and by means of the HUMARA assay. In addition, the latter revealed that the involved X-chromosome was the paternal one. The patients secondary amenorrhea and turneroid stigmata can reliably be ascribed to her nearly complete Xp deletion present in all cells. Thus, this observation is consistent with the well-known gradation of ovarian function depending on the Xp deletion size. We assume that the first event was an intrachromosome recombination during paternal meiosis between paralogous sequences at Xp11.2 and Xq21.2, which resulted in a fertilizing rea(X) spermatozoid. Early in embryogenesis, the rea(X) dissociated at the Xp11.2 junction point to originate the del(X), which in turn was healed by the de novo addition of telomeric repeats (the acentric Xq21.2→qter segment was lost in the process). The reverse sequence appears unlikely because it implies that the del(X) chromosome was healed only after it undergone a postzygotic interchromatid recombination and apposite segregation required to obtain the rea(X) clone. The present observation further expands the cytogenetic heterogeneity in Turner syndrome and may represent another instance of a terminal deletion healed by the de novo addition of telomeric repeats.