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PubMed2002

Neuronal changes during forebrain evolution in amniotes: an evolutionary developmental perspective.

Embryology is the interface of genetic inheritance and phenotypic expression in adult forms, and as such is uniquely positioned to illuminate both. Embryonic cell migration pattern, transient connectivity, axonal growth kinetics and fasciculation patterns can clearly be substantially impacted at the striatocortical junction, which appears to be critical for telencephalic development. Similarly, the big questions concerning pallial evolution in amniotes all involve the pivotal region at the pallial-subpallial boundary, an area where complex developmental cross-currents may be involved in the specification of multiple structures that are thus related to each other. We review some of the positions based on recent genetic data and/or hodology, then suggest that comparative studies of intervening, embryological events may resolve some of the apparent conflicts and illuminate the evolutionary scenario. We propose a new hypothesis, the collopallial field hypothesis, which specifies that the anterior dorsal ventricular ridge of sauropsids and a set of structures in mammals--the lateral neocortex, basolateral amygdalar complex, and claustrum-endopiriform nucleus formation--are homologous to each other as derivatives of a common embryonic field. We propose that in mammals the laterally lying collopallium splits, or differentiates, into deep (claustroamygdalar) and superficial (neocortical) components, whereas in sauropsids, this split does not occur.

Animals↗

PubMed1997

HLA-G polymorphisms: neutral evolution or novel function?

HLA-G is a non-classical class Ib gene with many unusual features. Because of its unique expression pattern, which is primarily limited to fetal cells at the maternal fetal interface, this gene has gained the attention of many investigators. In this paper we review some of the novel features of HLA-G, with particular reference to polymorphic variants in the gene, and discuss the implications of these features for the potential function and evolutionary history of HLA-G.

Alleles↗

PubMed2003

Gas chromatography-multiplex coherent Raman spectroscopy.

A new detector for gas chromatography has been developed that is based upon nonlinear Raman spectroscopy. The resulting hyphenated instrument uses a simple windowless cell as the interface between the chromatograph and the spectroscopic detector. The eluents are detected using a unique spectrometer equipped with a broadband OPO. This spectrometer is capable of generating high-resolution coherent Raman signals that are suitable for rapid multichannel detection.

Chromatography, Gas↗

PubMed2002

Crystal structure of fragment D from lamprey fibrinogen complexed with the peptide Gly-His-Arg-Pro-amide.

The crystal structure of fragment D from lamprey fibrinogen has been determined at 2.8 A resolution. The 89 kDa protein was cocrystallized with the peptide Gly-His-Arg-Pro-amide, which in many fibrinogens-but not lamprey-corresponds to the B knob exposed by thrombin. Because lamprey fragment D is more than 50% identical in sequence with human fragment D, the structure of which has been reported previously, it was possible to use the method of molecular replacement. The space group of the lamprey crystals is P1; there are four molecules in the unit cell. Although the fragments are packed head to head by the same D:D interface as is observed in other related preparations containing fragments D, the tails are uniquely joined by an unnatural association of the terminal sections of the residual coiled coils from adjacent molecules. Some features of the lamprey structure are clearer than have been observed in previous fragment D structures, including the beta-chain carbohydrate cluster, for one, and the important gamma-chain carboxyl-terminal segment, for another. The most significant differences between the lamprey and human structures occur in connecting loops at the entryways to the beta-chain and gamma-chain binding pockets.

Animals↗

PubMed2005

Sugar-based gemini surfactants with peptide bonds-synthesis, adsorption, micellization, and biodegradability.

The sugar-based gemini surfactant with peptide bonds, N,N'-bisalkyl-N,N'-bis[2-(lactobionylamide)ethyl]hexanediamide (2C(n)peLac, in which n represents hydrocarbon chain lengths of 12 and 16), was synthesized by reacting adipoyl chloride with the corresponding monomeric surfactant N-alkyl-N'-lactobionylethylenediamine (C(n)peLac), which was obtained by reacting ethylenediamine with alkyl bromide and lactobionic acid. The adsorption and micellization properties of C(n)peLac and 2C(n)peLac were characterized by the measurement of their equilibrium and dynamic surface tension, steady-state fluorescence using pyrene as a probe, dynamic light scattering (DLS), and time-resolved fluorescence quenching (TRFQ), and their biodegradability was also investigated. The critical micelle concentration (cmc) decreases with an increase in the hydrocarbon chains from monomeric to gemini surfactants, whereas it increases with an increase in the chain length from 12 to 16 for both systems. The increases in both the hydrocarbon chain and the chain length of sugar-based surfactants reduce surface activities such as the ability to lower the surface tension, the occupied area per molecule, and the adsorption rate at the air/water interface. The sugar-based surfactants C(n)peLac and 2C(n)peLac exhibit unique aggregation behavior in aqueous solution. The DLS results indicate that the apparent hydrodynamic diameter of C(n)peLac micelles decreases sharply with increasing concentration, whereas that of 2C(n)peLac micelles decreases gradually. From the TRFQ measurement, it was observed that, as concentration increases, the aggregation numbers are almost constant for C(n)peLac, whereas they increase for 2C(n)peLac. These results imply that loosely packed micelles formed by sugar-based surfactants become tightly packed micelles as the concentration increases. Furthermore, it was found that 2C(n)peLac shows lower biodegradability than does C(n)peLac because it contains tertiary amines in the molecule.

Adsorption↗

PubMed1995

Molecular basis for interaction of the protein tyrosine kinase ZAP-70 with the T-cell receptor.

The crystal structure of the tandem SH2 domains of human ZAP-70 in complex with a peptide derived from the zeta-subunit of the T-cell receptor reveals an unanticipated interaction between the two domains. A coiled coil of alpha-helices connects the two SH2 domains, producing an interface that constitutes one of the two critical phosphotyrosine binding sites. These and other unique features provide the molecular basis for highly selective association of ZAP-70 with the T-cell receptor.

Amino Acid Sequence↗

PubMed2000

Structural basis of dimerization, coactivator recognition and MODY3 mutations in HNF-1alpha.

Maturity-onset diabetes of the young type 3 (MODY3) results from mutations in the transcriptional activator hepatocyte nuclear factor-1alpha (HNF-1alpha). Several MODY3 mutations target the HNF-1alpha dimerization domain (HNF-p1), which binds the coactivator, dimerization cofactor of HNF-1 (DCoH). To define the mechanism of coactivator recognition and the basis for the MODY3 phenotype, we determined the cocrystal structure of the DCoH-HNF-p1 complex and characterized biochemically the effects of MODY3 mutations in HNF-p1. The DCoH-HNF-p1 complex comprises a dimer of dimers in which HNF-p1 forms a unique four-helix bundle. Through rearrangements of interfacial side chains, a single, bifunctional interface in the DCoH dimer mediates both HNF-1alpha binding and formation of a competing, transcriptionally inactive DCoH homotetramer. Consistent with the structure, MODY3 mutations in HNF-p1 reduce activator function by two distinct mechanisms.

Binding Sites↗

PubMed2005

Crystal structure of the virulence gene activator AphA from Vibrio cholerae reveals it is a novel member of the winged helix transcription factor superfamily.

AphA is a member of a new and largely uncharacterized family of transcriptional activators that is required for initiating virulence gene expression in Vibrio cholerae, the causative agent of the frequently fatal epidemic diarrheal disease cholera. AphA activates transcription by an unusual mechanism that appears to involve a direct interaction with the LysR-type regulator AphB at the tcpPH promoter. As a first step toward understanding the molecular basis for tcpPH activation by AphA and AphB, we have determined the crystal structure of AphA to 2.2 angstrom resolution. AphA is a dimer with an N-terminal winged helix DNA binding domain that is architecturally similar to that of the MarR family of transcriptional regulators. Unlike this family, however, AphA has a unique C-terminal antiparallel coiled coil domain that serves as its primary dimerization interface. AphA monomers are highly unstable by themselves and form a linked topology, requiring the protein to partially unfold to form the dimer. The structure of AphA also provides insights into how it cooperates with AphB to activate transcription, most likely by forming a heterotetrameric complex at the tcpPH promoter.

Amino Acid Sequence↗

PubMed2005

COMMD proteins, a novel family of structural and functional homologs of MURR1.

MURR1 is a multifunctional protein that inhibits nuclear factor kappaB (NF-kappaB), a transcription factor with pleiotropic functions affecting innate and adaptive immunity, apoptosis, cell cycle regulation, and oncogenesis. Here we report the discovery of a new family of proteins with homology to MURR1. These proteins form multimeric complexes and were identified in a biochemical screen for MURR1-associated factors. The family is defined by the presence of a conserved and unique motif termed the COMM (copper metabolism gene MURR1) domain, which functions as an interface for protein-protein interactions. Like MURR1, several of these factors also associate with and inhibit NF-kappaB. The proteins designated as COMMD or COMM domain containing 1-10 are extensively conserved in multicellular eukaryotic organisms and define a novel family of structural and functional homologs of MURR1. The prototype of this family, MURR1/COMMD1, suppresses NF-kappaB not by affecting nuclear translocation or binding of NF-kappaB to cognate motifs; rather, it functions in the nucleus by affecting the association of NF-kappaB with chromatin.

Active Transport, Cell Nucleus↗

PubMed1997

Structural basis of the RNA-binding specificity of human U1A protein.

The RNP domain is a very common eukaryotic protein domain involved in recognition of a wide range of RNA structures and sequences. Two structures of human U1A in complex with distinct RNA substrates have revealed important aspects of RNP-RNA recognition, but have also raised intriguing questions concerning the origin of binding specificity. The beta-sheet of the domain provides an extensive RNA-binding platform for packing aromatic RNA bases and hydrophobic protein side chains. However, many interactions between functional groups on the single-stranded nucleotides and residues on the beta-sheet surface are potentially common to RNP proteins with diverse specificity and therefore make only limited contribution to molecular discrimination. The refined structure of the U1A complex with the RNA polyadenylation inhibition element reported here clarifies the role of the RNP domain principal specificity determinants (the variable loops) in molecular recognition. The most variable region of RNP proteins, loop 3, plays a crucial role in defining the global geometry of the intermolecular interface. Electrostatic interactions with the RNA phosphodiester backbone involve protein side chains that are unique to U1A and are likely to be important for discrimination. This analysis provides a novel picture of RNA-protein recognition, much closer to our current understanding of protein-protein recognition than that of DNA-protein recognition.

Amino Acid Sequence↗

PubMed1996

Pulmonary surfactant: no mere paint on the alveolar wall.

The gas-liquid interface within the alveolus is completely lined with a complex mixture of lipids and unique proteins termed pulmonary surfactant, which both reduces surface tension and permits it to vary directly with the radius of curvature. In this way it minimizes the work of breathing and permits alveoli of different sizes to exist in equilibrium. However, surfactant does far more in that it also controls fluid balance in the lung and appears to play a key role in host defence. Either a deficiency in surfactant or an aberrant surfactant results in atelectasis and oedema. The surfactant system is very dynamic: alveolar surfactant phosphatidylcholine, the principal component, having a half life of only a few hours, with as much as 85% being recycled. Although distortion of the alveolar type II cell is now accepted as the principal stimulus for release, much remains to be discovered of modulating factors and intracellular signalling in the control of surfactant homeostasis. Likewise, many questions remain concerning the control of synthesis of the surfactant phospholipids, neutral lipids and proteins and their assembly into the tubular myelin form of alveolar surfactant, the refining of the monolayer with breathing, the control of re-uptake of different components into the type II cells and the roles of the proteins.

Animals↗

PubMed2004

Carnosine uptake in rat choroid plexus primary cell cultures and choroid plexus whole tissue from PEPT2 null mice.

PEPT2 is functionally active and localized to the apical membrane of rat choroid plexus epithelial cells. However, little is known about the transport mechanisms of endogenous neuropeptides in choroid plexus, and the role of PEPT2 in this process. In the present study, we examined the uptake kinetics of carnosine in rat choroid plexus primary cell cultures and choroid plexus whole tissue from wild-type (PEPT2(+/+)) and null (PEPT2(-/-)) mice. Our results indicate that carnosine is preferentially taken up from the apical as opposed to basolateral membrane of cell monolayers, and that basolateral efflux in limited. Transepithelial flux of carnosine was not distinguishable from that of paracellular diffusion. The apical uptake of carnosine was characterized by a high affinity (K(m) = 34 microM), low capacity (V(max) = 73 pmol/mg protein/min) process, consistent with that of PEPT2. The non-saturable component was small (K(d) = 0.063 microL/mg protein/min) and, under linear conditions, was only 3% of the total uptake. Studies in transgenic mice clearly demonstrated that PEPT2 was responsible for over 90% of carnosine's uptake in choroid plexus whole tissue. These findings elucidate the unique role of PEPT2 in regulating neuropeptide homeostasis at the blood-cerebrospinal fluid interface.

Amino Acids↗

PubMed1988

Endothelial communication. State of the art lecture.

By virtue of its location at the interface of flowing blood and vascular tissue, the endothelial cell monolayer is in a unique position for interactions with soluble and cellular elements of the blood on one side and with component cells of the vascular tissue on the other. This brief review outlines humoral and contact-mediated endothelial communication with other cells, particularly the resident cells of the vessel wall. Evidence for gap junctional communication channels between endothelium and vascular cells is summarized and discussed in relation to endothelial ion channel activity. Myoendothelial gap junctional communication is proposed as a mechanism involved in vasorelaxation, either independent of or in concert with secreted endothelium-derived relaxing factor(s).

Acetylcholine↗

PubMed2006

Clinical pharmacology of the appeals and exception process: the interface of the patient, physician, and insurance company to assure appropriate care under Medicare Part D.

Personalized medicine considers factors unique and specific to each patient to make clinical decisions, including selecting pharmacotherapy. Drug formularies, including those available to enrollees in Medicare Part D, are based on group characteristics and financial considerations. Consequently, an appeal of a formulary's preferred drug selection may be necessary to ensure the best care of the patient. Consideration of basic principles of clinical pharmacology can be used to decide whether an exemption should be considered and to document specific reasons for the request.

Drug Prescriptions↗

PubMed1999

Immunobiology of the blood-brain barrier.

The brain microvessel endothelial cells (BMVEC) that form the blood-brain barrier are uniquely positioned to influence immune responses within the central nervous system. As the biological interface separating the blood from the brain extracellular fluid, BMVEC regulate the entry of leukocytes into the brain. In addition, through the release of various soluble factors that affect immune responses, BMVEC may modulate immune responses in the brain. This review addresses the interplay between the immune system and the blood-brain barrier as it relates to the regulation of CNS defense and immunity.

Animals↗

PubMed1996

Influence of titanium oxide and titanium peroxy gel on the breakdown of hyaluronan by reactive oxygen species.

The molecular events occurring at the interface between titanium and connective tissue were investigated in order to help explain the unique biocompatible properties of titanium implants and their successful osseointegration into bone tissue. In this study the influence of commercially pure titanium and titanium peroxy gels on the breakdown of the connective tissue component and serum derived factor, hyaluronan, by reactive oxygen species (ROS), produced during the insertion of an implant in vivo, was examined. Hyaluronan breakdown was monitored in vitro in the presence of a hydroxyl radical flux, generated in the presence and absence of titanium powder and discs. Parallel studies examined the breakdown of hyaluronan by hydroxyl radicals in the presence of a titanium peroxy gel, prepared by incubation of the titanium powder or discs in concentrated hydrogen peroxide. The hyaluronan degradation products were separated according to their hydrodynamic size by gel exclusion chromatography. Similarly, experiments were also performed examining the degradation of 2-deoxy-D-ribose by a hydroxyl radical flux in order to demonstrate the detrimental potential of the hydroxyl radicals and to provide a measure of the effectiveness of titanium and titanium peroxy gels as scavengers of ROS. Titanium reduced the harmful effects of the hydroxyl radicals on the breakdown of hyaluronan, presumably acting as a scavenger for the reactive species, possibly by absorbing them into its surface oxide layer, which spontaneously forms on the surface. In contrast, the formation of a titanium peroxy gel from the titanium powder or on the surface of titanium discs enhanced breakdown of both the hyaluronan chains and 2-deoxy-D-ribose. The implications of these findings with regards to the biocompatible nature of the titanium and the ability of these implants to successfully osseointegrate are discussed.

Biocompatible Materials↗

PubMed1993

The pain resource nurse training program: a unique approach to pain management.

Adequate pain management is a 24 hr a day responsibility for health-care professionals working with cancer patients. Because nurses spend more time with patients in pain than any other member of the health-care team, they play a central role in pain assessment and pain management. The City of Hope National Medical Center, a clinical cancer center, developed a pain management course for staff nurses entitled "The Pain Resource Nurse (PRN) Training Program." The purpose of this innovative course was to prepare staff nurses to assume an active role in pain management. Twenty-six registered nurses participated in the 40-hr didactic and clinical course. The curriculum included information on pain assessment, pharmacology, nondrug interventions, and cultural, ethical, and psychosocial issues related to pain. After completion of the course, program staff have remained available to the PRNs to provide current information on pain management, and to assist with role implementation and guidance on interfacing with staff. This paper reports on the development, implementation, and 3-mo evaluation of this unique program.

Education↗

PubMed2002

Surface-active phospholipid: a Pandora's box of clinical applications. Part I. The lung and air spaces.

Almost everywhere in the body there are phospholipids, not only comprising the lipid bilayer of membranes, but also in the free state. What is seldom appreciated, except in respirology, is that these 'free' phospholipids are unusual in that many are highly surface active. Surface activity is a property of certain substances (surfactants), conferred by their molecular constitution and configuration, which predisposes them to locate at interfaces because, in doing so, they reduce interfacial energy. When adsorbed (reversibly bound) to solid surfaces, surfactants can impart many highly desirable properties that have been widely studied and long accepted in the physical sciences, while their commercial applications have withstood the test of time. These desirable properties include lubricity (boundary lubrication), release (antistick) and dewatering, while providing a barrier to corrosion, abrasion, solute transmission and to biological microorganisms. Many of these offer obvious roles for surface-active phospholipid (SAPL), ranging from a corrosion inhibitor in the stomach to a load-bearing lubricant in the joints. This opens a veritable 'Pandora's box' of potential clinical applications. Part I of this review challenges traditional beliefs in respirology that 'surfactant' is unique to the lung and, moreover, that its actions are confined to the liquid-air interface. Evidence is discussed that, by binding to alveolar epithelium, SAPL imparts semi-permeability needed before channels pumping ions can also pump water vital for maintaining fluid balance. Evidence is also reviewed for a lining to upper airways, sinuses and Eustachian tube where it can act like a standard release agent.

Animals↗