Structure of Pyridoxal Kinase from Sheep Brain and Role of the Tryptophanyl Residues

The primary structure of sheep brain pyridoxal kinase has been determined by direct chemical and physical methods. The enzyme contains 312 amino acid residues with an acetylated methionine at the N-terminus, yielding a molecular mass of 34,861 Da. The functional role played by the two tryptophanyl residues in positions 52 and 244 of the polypeptide chain has been investigated by fluorescence spectroscopy. The tryptophanyl residues are not completely exposed to the rapidly relaxing solvent and they are poorly accessible to collisional quenchers. Chemical modification with NBS abolishes the catalytic activity of the kinase. The amino acid sequence of the sheep brain enzyme shows high similarity (86.2% identity) with the human pyridoxal kinase recently reported [Hanna, Turner, and Kirkness, (1997), J. Biol. Chem. 272, 10756–10760]. Comparison of the mammalian proteins with bacterial and yeast putative pyridoxal kinases retrieved from the Swiss-Prot data bank shows a low degree of overall similarity. In particular, the putative ATP-binding domain is conserved, whereas the region that appears to be crucial in the binding of the pyridoxal substrate is not. Thus, the assignment of the bacterial and yeast cDNA-deduced proteins as pyridoxal kinases should be taken with caution.     

Annual variations of adrenal gland hormones in the lizard <Emphasis Type="Italic">Podarcis sicula</Emphasis>

The adrenal gland regulates metabolism and maintains normal electrolyte balance. Adrenal hormones are equivalent in all vertebrates; the chromaffin tissue produces adrenaline and noradrenaline and the steroidogenic tissue produces most of the steroid hormones present in mammals. Podarcis sicula belongs to the Squamata family of lizards and it is the most abundant lizard species in southern Italy. This species shows a reproductive annual cycle and the presence of seasonal variations in the activity of the hypothalamus-hypophyseal-thyroid axis. To investigate the existence of an annual cycle of lizard adrenal gland, we have measured plasma concentrations of corticosterone, ACTH, noradrenaline and adrenaline. We have shown that corticosterone rapidly increased from January to March to reach a peak value that persisted until July, then, it slowly decreased until December. ACTH levels increased from January to May and slowly decreased from July to December. Noradrenaline levels were higher in March and then decreased until December. On the contrary, adrenaline levels increased from March to July and slowly decreased until December. Our results demonstrate the existence of an annual cycle of the lizard adrenal gland activity. This is very interesting because its activity is important to rightly regulate the reproductive status of the Podarcis sicula lizard.     

Different patterns of expression of five neuropeptides in the adrenal gland and kidney of two species of frog

The aim of this study was to demonstrate in the adrenocortical and renal tissues of two species of frog, Rana italica and Rana esculenta, the presence and distribution of five neuropeptides: atrial natriuretic peptide (ANP), Leu-enkephalin (Leu-ENK), neuropeptide Y (NPY), substance P (SP) and vasoactive intestinal peptide (VIP).In anurans, the adrenal medulla is the site for the synthesis, storage and secretion of not only catecholamines but also various peptides. These peptides should not be regarded only as neurotransmitters or modulators for the secretion of catecholamines, but also as hormonal substances that induce systemic effects.All the peptides studied (ANP, Leu-ENK, NPY, SP and VIP) are present in both organs. However, different patterns of expression were observed for some of the peptides in two frogs.Immunopositivity to ANP was found in small clusters of chromaffin cells in both frogs whereas a clear strong positivity was present only in Rana esculenta kidney. Large clusters of chromaffin cells were immunoreactive to Leu-ENK in Rana italica but there were approximately 25% fewer compared to the positive cells present in Rana esculenta. Epithelial cells of renal tubules showed strong immunopositivity to Leu-ENK in Rana esculenta but not in Rana italica. A large number of adrenal cells (70–80%) were immunoreactive to NPY in Rana italica, while in Rana esculenta this peptide was localized in small clusters of chromaffin cells. Both frogs showed many NPY-positive cells in kidney. Many chromaffin cells were found positive to SP and VIP. A strong positivity was also observed in kidney in both frogs. These observations suggest a possible role of these peptides in the control of the physiological functions of adrenal glands and kidney of the two species of frogs studied.     

The Bw4/Bw6 difference between HLA-B*0802 and HLA-B*0801 changes the peptides endogenously bound and the stimulation of alloreactive T cells

 HLA-B^*0801 is unique among HLA-B allotypes in having dominant amino acid anchors at positions 3 and 5 of the peptide-binding motif. HLA-B^*0802 is a variant of HLA-B^*0801 in which the Bw6 sequence motif is replaced by a Bw4 sequence motif. This change, involving substitutions at positions 77, 80, 81, 82, and 83 of the B^*08 heavy chain, is probably the result of a single evolutionary event of interallelic conversion. Moreover, the difference between B^*0802 and B^*0801 is sufficient to stimulate a cytotoxic T-cell response. To assess further the functional impact of the Bw4 motif on a B8 background, we compared the peptide-binding specificity of the B^*0801 and B^*0802 allotypes by sequencing the mixture of peptides endogenously bound to B^*0802 and 12 individual peptides purified from that mixture. The HLA-B^*0802 allotype, while able to bind some peptides bound by B^*0801, has a broader repertoire of endogenously bound peptides than B^*0801: the peptides bound by B^*0802 are more variable in length and exhibit greater diversity in the carboxyl-terminal amino acid which interacts with the F pocket. Received: 29 October 1997     

Hippocampal signal complexity in mesial temporal lobe epilepsy: a noisy brain is a healthy brain

Patients with mesial temporal lobe epilepsy (mTLE) show structural and functional abnormalities in hippocampus and surrounding mesial temporal structures. Brain signal complexity appears to be a marker of functional integrity or capacity. We examined complexity in 8 patients with intracranial hippocampal electrodes during performance of memory tasks (scene encoding and recognition) known to be sensitive to mesial temporal integrity. Our patients were shown to have right mesial temporal seizure onsets, permitting us to evaluate both epileptogenic (right) and healthy (left) hippocampi. Using multiscale entropy (MSE) as a measure of complexity, we found that iEEG from the epileptogenic hippocampus showed less complexity than iEEG from the healthy hippocampus. This difference was reliable for encoding but not for recognition. Our results indicate that both functional integrity and cognitive demands influence hippocampal signal complexity.     

Cytokine gene polymorphisms and atopic disease in two European cohorts. (ECRHS-Basel and SAPALDIA)

Background

Avoidance of allergens is still recommended as the first and best way to prevent allergic illnesses and their comorbid diseases. Despite a variety of attempts there has been very limited success in the area of environmental control of allergic disease. Our objective was to identify a non-invasive, non-pharmacological method to reduce indoor allergen loads in atopic persons' homes and public environments. We employed a novel in vivo approach to examine the possibility of using aluminum sulfate to control environmental allergens.

Methods

Fifty skin test reactive patients were simultaneously skin tested with conventional test materials and the actions of the protein/glycoprotein modifier, aluminum sulfate. Common allergens, dog, cat, dust mite, Alternaria, and cockroach were used in the study.

Results

Skin test reactivity was significantly reduced by the modifier aluminum sulfate. Our studies demonstrate that the effects of histamine were not affected by the presence of aluminum sulfate. In fact, skin test reactivity was reduced independent of whether aluminum sulfate was present in the allergen test material or removed prior to testing, indicating that the allergens had in some way been inactivated.

Conclusion

Aluminum sulfate was found to reduce the in vivo allergic reaction cascade induced by skin testing with common allergens. The exact mechanism is not clear but appears to involve the alteration of IgE-binding epitopes on the allergen. Our results indicate that it may be possible to diminish the allergenicity of an environment by application of the active agent aluminum sulfate, thus producing environmental control without complete removal of the allergen.     

Systems analysis of primary Sjögren's syndrome pathogenesis in salivary glands identifies shared pathways in human and a mouse model

Bone tissue has an exceptional quality to regenerate to native tissue in response to injury. However, the fracture repair process requires mechanical stability or a viable biological microenvironment or both to ensure successful healing to native tissue. An improved understanding of the molecular and cellular events that occur during bone repair and remodeling has led to the development of biologic agents that can augment the biological microenvironment and enhance bone repair. Orthobiologics, including stem cells, osteoinductive growth factors, osteoconductive matrices, and anabolic agents, are available clinically for accelerating fracture repair and treatment of compromised bone repair situations like delayed unions and nonunions. Preclinical and clinical studies using biologic agents like recombinant bone morphogenetic proteins have demonstrated an efficacy similar or better than that of autologous bone graft in acute fracture healing. A lack of standardized outcome measures for comparison of biologic agents in clinical fracture repair trials, frequent off-label use, and a limited understanding of the biological activity of these agents at the bone repair site have limited their efficacy in clinical applications.