The dorsal cyst in holoprosencephaly and the role of the thalamus in its formation

The dorsal cyst is poorly understood, although it is commonly encountered in holoprosencephaly. We endeavor to establish the role of diencephalic malformations in the formation of the dorsal cyst and speculate on the developmental factors responsible. We reviewed the imaging of 70 patients with holoprosencephaly (MRI of 50 and high-quality CT of 20). The presence or absence of a dorsal cyst, thalamic noncleavage and abnormal thalamic orientation were assessed for statistical association, using Fisher's Exact Test and logistical regression. The presence of a dorsal cyst correlated strongly with the presence of noncleavage of the thalamus (P = 0.0007) and with its degree (P < 0.00005). There was a trend toward an association between abnormalities in the orientation of the thalamus and the dorsal cyst, but this was not statistically significant (P = 0.07). We speculate that the unseparated thalamus physically blocks egress of cerebrospinal fluid from the third ventricle, resulting in expansion of the posterodorsal portion of the ventricle to form the cyst.

Antibacterial agents based on the cyclic D,L-alpha-peptide architecture

The rapid emergence of bacterial infections that are resistant to many drugs underscores the need for new therapeutic agents. Here we report that six- and eight-residue cyclic d,l-alpha-peptides act preferentially on Gram-positive and/or Gram-negative bacterial membranes compared to mammalian cells, increase membrane permeability, collapse transmembrane ion potentials, and cause rapid cell death. The effectiveness of this class of materials as selective antibacterial agents is highlighted by the high efficacy observed against lethal methicillin-resistant Staphylococcus aureus infections in mice. Cyclic d,l-alpha-peptides are proteolytically stable, easy to synthesize, and can be derived from a potentially vast membrane-active sequence space. The unique abiotic structure of the cyclic peptides and their quick bactericidal action may also contribute to limit temporal acquirement of drug resistant bacteria. The low molecular weight d,l-alpha-peptides offer an attractive complement to the current arsenal of naturally derived antibiotics, and hold considerable potential in combating a variety of existing and emerging infectious diseases.

Biochemical, electrophysiological and neurohormonal studies with B-20991, a selective 5-HT1A receptor agonist

Different receptor subtypes mediate the effects produced by serotonin (5-HT) in mammals. Besides their proved anxiolytic action, agonists of the 5-HT1A receptor subtype show prospects as antidepressants or neuroprotective agents in case of ischemia. In order to better define the pharmacological profile and determine the selectivity for the 5-HT receptor type, the properties of the new 5-HT1A receptor agonist 2[[4-(o-methoxyphenyl)piperazin-1-yl]-methyl]-1.3-dioxoperhydroimidazo[1.5-a]pyridine (B-20991), an arylpiperazine derivative, have now been further studied. B-20991 was found to antagonize the forskolin-induced increase of cAMP synthesis in a HeLa cell line transfected with the human 5-HT1A in a process sensitive to the selective blocker N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl-cyclohexanecarboxamide maleate (WAY 100635). Additionally, B-20991 showed a dose-dependent inhibition of the spontaneous on-going activity of serotonin (5-HT) neurons in the dorsal raphe nucleus in rats, an effect that was reversed by treatment with WAY 100635. This, together with the fact that the hypothermia induced by B-20991 in mice was also antagonized by WAY 100635, suggests that the new compound acts upon somatodendritic 5-HT1A receptors. Additional activation of 5-HT1A postsynaptic receptors was indicated by the increase of corticosterone plasma levels induced by B-20991 in the rat. These results demonstrate that B-20991 is a selective 5-HT1A receptor agonist acting both pre- and postsynaptically, which represents an useful pharmacological tool to study 5-HT1A-receptor-mediated effects.

Inhibition of endotoxin-induced macrophage chemokine production by vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide in vitro and in vivo

Inflammatory chemokines recruit various populations of immune cells that initiate and maintain the inflammatory response against foreign Ags. Although such a response is necessary for the elimination of the Ag, the inflammation has to be eventually resolved in a healthy organism. Neuropeptides such as vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP), released after antigenic stimulation, contribute to the termination of an inflammatory response primarily by inhibiting the production of proinflammatory cytokines. Here we investigated the effects of VIP and PACAP on chemokine production. We report that VIP and PACAP inhibit the expression of the macrophage-derived CXC chemokines macrophage inflammatory protein-2 and KC (IL-8), and of the CC chemokines MIP-1alpha, MIP-1beta, monocyte chemoattractant protein 1, and RANTES in vivo and in vitro. The inhibition of chemokine gene expression correlates with an inhibitory effect of VIP/PACAP on NF-kappaB binding and transactivating activity. The VIP/PACAP inhibition of both chemokine production and of NF-kappaB binding and transactivating activity is mediated through the specific VIP receptor VPAC1, and involves both cAMP-dependent and -independent intracellular pathways. In an in vivo model of acute peritonitis, the inhibition of chemokine production by VIP/PACAP leads to a significant reduction in the recruitment of polymorphonuclear cells, macrophages, and lymphocytes into the peritoneal cavity. These findings support the proposed role of VIP and PACAP as key endogenous anti-inflammatory agents and describe a novel mechanism, i.e., the inhibition of the production of macrophage-derived chemokines.

Bacterial colonization of endotracheal tubes in intubated neonates

OBJECTIVE

To obtain in vivo bacterial colonization profiles on endotracheal tubes at different sites in the neonatal airway in an attempt to better characterize one potential element of chondritis.

DESIGN

A case series in which cultures were obtained from calculated segments of 33 endotracheal tubes immediately following extubation. This allowed for sampling at specific levels of the airway corresponding to the trachea, the subglottis, and the oropharynx. Data collected included gender, race, duration of intubation, use of antibiotic therapy, comorbidities, gestational age at birth and extubation, crown-rump length, weight, radiographic distance from tube tip to carina, and culture results.

SETTING

Newborn intensive care unit at a tertiary care medical center.

PATIENTS

Twenty-nine neonates intubated for longer than 24 hours (range, 24 hours to 15 days).

MAIN OUTCOME MEASURES

Bacterial and fungal cultures obtained from 3 endotracheal tube segments for each extubation.

RESULTS

A statistically significant difference (P < .05) was found in colonization rates between patients intubated for less than 4 days and those intubated for longer periods. No significant difference was noted in bacterial profile between the 3 sites.

CONCLUSIONS

Data demonstrate that bacterial colonization of an indwelling object in the neonatal airway increases with the duration of intubation. Furthermore, 4 days seems to represent a critical period in the formation of such colonization (possibly in the form of a biofilm). These bacteria may contribute to the chondritis known to precede the development of subglottic stenosis. Further studies are indicated to suggest ways to interrupt this process and reduce the incidence of airway injury.

Immunogenicity of recombinant class 1 protein from Neisseria meningitidis refolded into phospholipid vesicles and detergent

The possibility of eliciting bactericidal antibodies against a recombinant class 1 protein (P1) from Neisseria meningitidis, joined to the first 45 amino acids of the neisserial LpdA protein (PM82), was examined. P1 was produced in Escherichia coli as intracellular inclusion bodies, from which it was purified and reconstituted by (a) inclusion into phospholipid vesicles and detergent and (b) refolding in 0.1% SDS. When Balb/c mice were immunised, high titres of subtype-specific bactericidal antibodies against P1 were obtained in both cases. These results suggest that in spite of being a denaturing agent, it is possible to use SDS to reconstitute the P1 protein in a conformation that exposes the immunodominat regions.

Vasoactive intestinal peptide prevents experimental arthritis by downregulating both autoimmune and inflammatory components of the disease

Rheumatoid arthritis (RA) is a chronic and debilitating autoimmune disease of unknown etiology, characterized by chronic inflammation in the joints and subsequent destruction of the cartilage and bone. We describe here a new strategy for the treatment of arthritis: administration of the neuropeptide vasoactive intestinal peptide (VIP). Treatment with VIP significantly reduced incidence and severity of arthritis in an experimental model, completely abrogating joint swelling and destruction of cartilage and bone. The therapeutic effect of VIP was associated with downregulation of both inflammatory and autoimmune components of the disease. Our data indicate VIP as a viable candidate for the development of treatments for RA.

Cutting edge: is vasoactive intestinal peptide a type 2 cytokine?

A component of the chemical language shared by the immune and nervous system is the expression of neuropeptides by immune cells. Vasoactive intestinal peptide (VIP) was shown to be produced by T lymphocytes. Here we investigate whether T cell subsets differentially express VIP. Our studies indicate that, upon specific Ag stimulation, Th2 and T2 cells, but not Th1 and T1 cells derived from TCR transgenic (Tg) mice, express VIP mRNA and protein, and secrete VIP. Following immunization with the specific Ag, significant levels of VIP are present in the serum of syngeneic, non-Tg hosts that receive Th2, but not Th1 Tg cells. Th2 Tg cells recovered from the non-Tg hosts immunized with the specific Ag, but not with an irrelevant Ag, express intracellular VIP. Because VIP is produced by Ag-stimulated type 2 T cells, and differentially affects Th1 and Th2 cells, could VIP be viewed as a type 2 cytokine?

VIP and PACAP inhibit activation induced apoptosis in T lymphocytes

Apoptosis in T and B lymphocytes is a major element controlling the immune response. Activation induced cell death (AICD) in T cells is a main mechanism for maintaining peripheral tolerance and for limiting an ongoing immune response. AICD is initiated by antigen reengagement of the T cell receptor (TCR), and mediated through Fas/Fas ligand (FasL) interactions. VIP and PACAP are two multifunctional neuropeptides present in the lymphoid microenvironment that act primarily as anti-inflammatory agents. In this study we report on the role of VIP and PACAP on T cell AICD, and on the mechanisms involved. VIP and PACAP inhibit AICD in vivo and in vitro, in peripheral T cells and T cell hybridomas. The effect is dose dependent and is mediated through the specific receptors VPAC1 and VPAC2. The inhibition of AICD is achieved through reduction in FasL expression at protein and mRNA level. By affecting FasL expression, VIP and PACAP may play a physiological role in both the generation of memory T cells and the inhibition of FasL-mediated T cell cytotoxicity.

Receptors and transcriptional factors involved in the anti-inflammatory activity of VIP and PACAP

VIP and PACAP modulate the function of inflammatory cells through specific receptors. VIP/PACAP inhibit the production of TNF alpha, IL-6, IL-12, and nitric oxide (NO), and stimulate IL-10 in peritoneal macrophages and Raw 264.7 cells. Here we report on the specific VIP/PACAP receptors, transduction pathways, and transcriptional factors involved in the regulation of these macrophage factors by VIP and PACAP. Both neuropeptides inhibit IL-6 production mainly through PAC1 binding, PKC activation, and the subsequent shedding of the LPS receptor CD14 in macrophages. However, the effects on TNF alpha, IL-10, IL-12, and NO are mostly mediated through the constitutively expressed VPAC1 receptor, although the inducible expressed VPAC2 may also participate. VIP/PACAP binding to VPAC1 induces both a cAMP-dependent and a cAMP-independent pathways that regulate cytokine and NO production at the transcriptional level. VIP/PACAP inhibit TNF alpha through reduction in NFkB binding and changes in the composition of CRE-binding complexes; they inhibit IL-12 through reduction in NFkB binding and changes in the composition of the ets-2 complexes. VIP/PACAP inhibit iNOS expression through reduction in NFkB and IRF-1 binding, and augment IL-10 by increasing CREB-binding. Whereas the inhibition of IRF-1 and CRE-binding complexes seems to be mediated through the cAMP-dependent pathway, VIP/PACAP inhibition of NFkB nuclear translocation is mediated through a reduction in IkB alpha degradation mediated by the cAMP-independent pathway. This study provides new evidence for the understanding of the molecular mechanism by means of which VIP and PACAP attenuate the inflammatory response.

Modification of wheat rDNA loci by rye B chromosomes: a chromatin organization model

The rDNA loci, and their associated NORs, on chromosomes 1B and 6B of the hexaploid wheat cv. Lindström have been used as a chromatin marker to investigate the functional basis of the phenotype effects of introgressed supernumerary B chromosomes (Bs) of rye. The rye Bs themselves lack genes, other than those which determine their mitotic drive mechanism, and the way in which they can modulate characters determined by the A chromosome background has always been a puzzle. An isogenic line of Lindström plants carrying different numbers of Bs was used as the experimental system to see how different doses of Bs (from 0 to 6) affected the activity of the wheat NORs and the organization of their rDNA loci at interphase. Silver staining on metaphase chromosomes was used to evaluate the previous activity of the NORs, and to reveal variations in their size; and the pTa71 FISH probe from wheat was used to visualize structural modifications to the interphase rDNA loci. A single B had no measurable effect, but, as the B-number increased, there were significant changes in the physical dimensions of the metaphase NORs, reflecting reduced levels of their activity earlier in the cell cycle, and also in the condensation patterns of the interphase rDNA loci. In addition, the higher B-numbers caused a size heteromorphism between the homologous NORs. A model is discussed which interprets the phenotypic effects of Bs generically, in nucleotypic terms, based of their being 'genetically inert' but 'chromosomally active'.

[The usefulness of sucralfate in postoperative improvement of children's tonsillectomy]

INTRODUCTION

Sucralfate is an effective agent in the treatment of peptic ulcer, mixing up the fibrinous exudate of duodenal ulcer to form a protective barrier promoting its healing. Similarly the deprived muscle in the tonsillar bed results protected and consequently bring down the post-surgical morbidity.

OBJECTIVE

The aim of this study has been to ascertain the suitability of sucralfate in alleviating symptoms after tonsil's removal.

MATERIAL AND METHODS

205 children were included in the study and randomly postoperative treated with sucralfate. A lot of different parameters were controlled afterwards such as days with pain, taken of analgesics, return to normal diet, fever, bloody saliva, halitosis or vomits.

RESULTS

There was a significant association between the use of sucralfate and less days with sore throat, less pain and analgesia required.

CONCLUSIONS

The use of sucralfate means and efficient measure in order to alleviate the pain and postoperative discomfort associated with tonsils removal, being a cheap drug and without having topical after-effects.

VIP and PACAP induce shift to a Th2 response by upregulating B7.2 expression

VIP and PACAP, two structurally related neuropeptides produced within the lymphoid microenvironment, modulate several immunological functions. Although primarily anti-inflammatory in nature, VIP and PACAP also affect resting macrophages. In this study, we report on the role of VIP and PACAP on macrophage B7 expression and costimulatory function for antigen-primed CD4+ T cells, and on the macrophage-induced regulation of Th1/Th2 differentiation in vitro and in vivo. VIP and PACAP upregulate B7.2, but not B7.1, MHC class II, or ICAM-1 expression, and activate macrophages to stimulate the proliferation of naïve T cells in response to soluble anti-CD3 or allogeneic stimulation. The stimulatory effect is mediated through the specific receptor VPAC1, and involves the cAMP/PKA pathway as second messengers. The enhancement in B7.2 expression occurs at both mRNA and protein levels, and correlates with the VIP/PACAP induced upregulation of the costimulatory activity of macrophages for antigen-primed CD4+ T cells. VIP/PACAP-treated macrophages gain the ability to induce Th2-type cytokines such as IL-4 and IL-5, and to reduce Th1-type cytokines such as IFN gamma and IL-2. In vivo administration of VIP or PACAP in antigen-immunized mice reduces the numbers of IFN gamma-secreting cells, enhances the numbers of IL-4-secreting cells, and affects the pattern of antigen-specific Ig isotypes. The preferential differentiation into Th2 effector cells induced by VIP/PACAP-treated macrophages is mediated through the upregulation of B7.2 expression. Since Th1-dominated responses are associated with some autoimmune diseases and inflammatory reactions typical of cell-mediated immunity, the VIP/PACAP inhibition of Th1 development may represent an additional mechanism for the general anti-inflammatory activity of the two neuropeptides.

Cryptococcus neoformans in bird excreta in the city zoo of Cali, Colombia

The presence of Cryptococcus neoformans was studied in bird excreta and in the air circulating in and around bird cages in the City Zoo of Cali, Colombia, between August 1994 and April 1995, using a sunflower seed agar culture medium for fungus isolation. A total of 380 samples was studied, 110 from droppings and 270 from Petri dishes placed inside (148) and outside (122) the cages. C. neoformans var neoformans was found in only two cases, one from bird excreta (0.9%) and the other from air inside a cage (0.7%). The former positive sample was collected from the cracks of a dead tree where two crested caracaras (Polyborus plancus) roosted; the feces were dry, accumulated, and with a pH of 6. The other positive sample was found inside the cage of these birds; however, samples taken in a dispersion study at 0.5, 1, 5 and 10 m around this cage were all negative. It appears that this low isolation rate is due to adequate cleaning and disinfection procedures used in the city zoo of Cali.

Inhibitory neuropeptide receptors on macrophages

The immune response, both in innate and adaptive immunity, is controlled at several levels, including signaling from the central nervous system. Neuropeptides released within the lymphoid organs modulate the immune response, either as stimulators or inhibitors. The subject of this review is the description of macrophage-expressed receptors of inhibitory neuropeptides. We describe the inhibitory effects on macrophage function for several neuropeptides, the receptors that mediate those activities, and the molecular mechanisms initiated by some of these receptors in terms of transduction pathways and transcriptional factors.

Mapping of monoclonal antibodies specific to P64k: A common antigen of several isolates of Neisseria meningitidis

P64k is a minor outer membrane protein from Neisseria meningitidis. This protein has been produced at high levels in Escherichia coli. We generated a group of monoclonal antibodies (mAbs) against recombinant P64k, which recognise four non-overlapping epitopes, as shown using competition assays with biotinylated mAbs. The P64k sequences involved in mAbs binding were mapped with synthetic overlapping peptides derived from the P64k protein, and located in the previously determined three-dimensional structure of the protein. These antibodies were also characterised by whole-cell ELISA and bactericidal tests against N. meningitidis. Only two of the recognised epitopes were exposed on the bacterial surface, and none of the mAbs showed bactericidal activity. The relationship between these results and the structural data on the epitopes bound by the mAbs is discussed.Key words: Neisseria meningitidis, P64k, monoclonal antibodies, epitope mapping.

Mapping of monoclonal antibodies specific to P64k: a common antigen of several isolates of Neisseria meningitidis

P64k is a minor outer membrane protein from Neisseria meningitidis. This protein has been produced at high levels in Escherichia coli. We generated a group of monoclonal antibodies (mAbs) against recombinant P64k, which recognise four non-overlapping epitopes, as shown using competition assays with biotinylated mAbs. The P64k sequences involved in mAbs binding were mapped with synthetic overlapping peptides derived from the P64k protein, and located in the previously determined three-dimensional structure of the protein. These antibodies were also characterised by whole-cell ELISA and bactericidal tests against N. meningitidis. Only two of the recognised epitopes were exposed on the bacterial surface, and none of the mAbs showed bactericidal activity. The relationship between these results and the structural data on the epitopes bound by the mAbs is discussed.

Vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide inhibit expression of Fas ligand in activated T lymphocytes by regulating c-Myc, NF-kappa B, NF-AT, and early growth factors 2/3

Activation-induced cell death in T cells, a major mechanism for limiting an ongoing immune response, is initiated by Ag reengagement and mediated through Fas/Fas ligand interactions. Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP), two multifunctional neuropeptides, modulate innate and adaptive immunity. We reported previously that VIP/PACAP protect T cells from activation-induced cell death through down-regulation of Fas ligand (FasL). In this study, we investigate the molecular mechanisms involved in the protective effect of VIP and PACAP. VIP/PACAP reduce in a dose-dependent manner anti-CD3-induced apoptosis in 2B4.11 T cell hybridomas. The protective effect is mediated through the specific type 2 VIP receptor, and the cAMP/protein kinase A pathway. A functional study demonstrates that VIP/PACAP inhibit activation-induced FasL expression. VIP/PACAP inhibit the expression and/or DNA-binding activity of several transcriptional factors involved in FasL expression, i.e., c-myc, NF-kappaB, NF-ATp, and early growth factors (Egr) 2/3. The inhibition of NF-kappaB binding is due to the stabilization of I-kappaB (inhibitory protein that dissociates from NF-kappaB), through the inhibition of I-kappaB kinase alpha activity. Subsequently, p65 nuclear translocation is significantly reduced. The inhibition in NF-ATp binding results from a calcineurin-independent reduction in NF-ATp nuclear translocation. VIP/PACAP inhibit the expression of Egr2 and 3, but not of Egr1. The effects on the transcriptional factors are mediated through type 2 VIP receptor with cAMP as secondary messenger.

Vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide inhibit nuclear factor-kappa B-dependent gene activation at multiple levels in the human monocytic cell line THP-1

The neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) suppress monocyte/macrophage production of proinflammatory agents. The transcription factor NF-kappa B regulates the transcription of most agents. VIP/PACAP inhibit NF-kappa B transactivation in the lipopolysaccharide-stimulated human monocytic cell line THP-1 at multiple levels. First, VIP/PACAP inhibit p65 nuclear translocation and NF-kappa B DNA binding by stabilizing the inhibitor I kappa B alpha. Second, VIP/PACAP induce phosphorylation of the CRE-binding protein (CREB) and its binding to the CREB-binding protein (CBP). This results in a decrease in p65.CBP complexes, which further reduces NF-kappa B transactivation. Third, VIP and PACAP reduce the phosphorylation of the TATA box-binding protein (TBP), resulting in a reduction in TBP binding to both p65 and the TATA box. All these effects are mediated through the specific receptor VPAC1. The cAMP/cAMP-dependent protein kinase pathway mediates the effects on CBP and TBP, whereas a cAMP-independent pathway is the major transducer for the effects on p65 nuclear translocation. Since NF-kappaB represents a focal point for various stimuli and induces the expression of many proinflammatory genes, its targeting by VIP and PACAP positions them as important anti-inflammatory agents. The VIP/PACAP inhibition of NF-kappa B at various levels and through different transduction pathways could offer a significant advantage over other anti-inflammatory agents.

Mining association rules with improved semantics in medical databases

The discovery of new knowledge by mining medical databases is crucial in order to make an effective use of stored data, enhancing patient management tasks. One of the main objectives of data mining methods is to provide a clear and understandable description of patterns held in data. We introduce a new approach to find association rules among quantitative values in relational databases. The semantics of such rules are improved by introducing imprecise terms in both the antecedent and the consequent, as these terms are the most commonly used in human conversation and reasoning. The terms are modeled by means of fuzzy sets defined in the appropriate domains. However, the mining task is performed on the precise data. These "fuzzy association rules" are more informative than rules relating precise values. We also introduce a new measure of accuracy, based on Shortliffe and Buchanan's certainty factors [Shortliffe E, Buchanan B. Math Biosci 1975;23:351-79]. Also, the semantics of the usual measure of usefulness of an association rule, called support are discussed and some new criteria are introduced. Our new measures have been shown to be more understandable and appropriate than ordinary ones. Several experiments on large medical databases show that our new approach can provide useful knowledge with better semantics in this field.