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1.
Eur Ann Allergy Clin Immunol ; 53(6): 277-279, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34148334

ABSTRACT

SUMMARY: Birt-Hogg-Dubé (BHD) syndrome is a rare genetic pathology characterized by cutaneous fibrofolliculomas, pulmonary cysts and kidney tumours. Severe asthma is the most serious form of asthma that does not respond to standard treatments. We present the case of a 68 years-old male patient who had frequent respiratory tract infections, shortness of breath and decline in lung function, nasal polyposis and hypertrophy of the nasal turbinates, for this reason was treated as a severe asthmatic patient for several years with ICS + LABA and high doses of OCS. When we tried to reduce OCS the patient had worsening of the symptoms, we requested a HRTC scan that showed presence of several cysts spread ubiquitously. The patient had a family history of pneumothorax, for this reason we requested a genetic test that resulted in a heterozygous point mutation on exon 12 (c.1429 C > T) of FLCN gene. Despite the diagnosis of BHD syndrome, the patient's clinical condition kept on suggesting an underlying severe asthma and the blood tests we requested pointed out a high percentage of eosinophils, for this reason we opted for the administration of benralizumab that resulted in an excellent asthma control and increased quality of life.


Subject(s)
Asthma , Birt-Hogg-Dube Syndrome , Aged , Antibodies, Monoclonal, Humanized , Asthma/diagnosis , Asthma/drug therapy , Birt-Hogg-Dube Syndrome/complications , Birt-Hogg-Dube Syndrome/diagnosis , Birt-Hogg-Dube Syndrome/drug therapy , Humans , Male , Proto-Oncogene Proteins/genetics , Quality of Life , Tumor Suppressor Proteins/genetics
2.
J Microsc ; 279(3): 242-248, 2020 09.
Article in English | MEDLINE | ID: mdl-32157689

ABSTRACT

Liquid phase transmission electron microscopy allows the imaging of materials in liquid environments. The sample is encapsulated within electron-beam transparent windows and hence protected by the ultrahigh vacuum necessary within the electron gun. Such an approach allows to study biological and soft materials in their natural environment and offers the possibility of accessing their dynamic nature. Yet, the electron beam scattering from the windows and solvent increases the image noise and blur. Herein, we propose a pipeline to both de-noise and sharpen images obtained by liquid transmission electron microscopy. We develop the workflow in a way that it does not require any human interference, nor introduce artefacts, but actually unveils features of the imaged samples covered by the noise and the blur. LAY DESCRIPTION: Transmission Electron Microscopy TEM is one of the most powerful techniques for structural determination at the nanoscale, with the ability to image matter down to the atomic level. TEM is only possible by keeping the electron beam under high vacuum in order to avoid undesired scattering events in the beam path. High vacuum means that the TEM samples must conventionally be in solid-state. Thus, samples in liquid form or containing liquids, like water, need special preparation techniques which tend to alter the structure and chemical nature of the sample. Such alterations are particularly critical for biological and soft organic materials where the structures are controlled by the presence of water and/or other liquids. The development of new cameras, materials and sample holders have made possible for TEM to be performed on liquid samples. Liquid Phase Transmission Electron Microscopy (LTEM) offers the possibility to investigate nanoscopic structures in liquid state and monitor dynamic processes. However important limitations come from the liquid nature of samples in the imaging process such as the low contrast afforded by organic and biological materials and additional noise and blur introduced by the liquid sample and its thickness. Existing image analysis algorithms for TEM result inadequate for LTEM. The end-to-end image analysis method herein has the ability to recover the original images together with their sharpness, without introducing any artefacts. The proposed algorithms offer the great advantage of unveiling image details which are not usually seen during imaging, thus allowing a better understanding of the nature, structure and ultimately the function of the investigated structures. The fully automatised analysis method allows to efficiently process dozens of images in few hours, improving dramatically the performance of LTEM imaging.

3.
Biochim Biophys Acta Gen Subj ; 1861(1 Pt B): 3661-3670, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27212689

ABSTRACT

BACKGROUND: Neutron sources are increasingly employed in a wide range of research fields. For some specific purposes an alternative to existing large-scale neutron scattering facilities, can be offered by the new generation of portable neutron devices. SCOPE OF REVIEW: This review reports an overview for such recently available neutron generators mainly addressed to biophysics applications with specific reference to portable non-stationary neutron generators applied in Neutron Activation Analysis (NAA). MAJOR CONCLUSIONS: The review reports a description of a typical portable neutron generator set-up addressed to biophysics applications. GENERAL SIGNIFICANCE: New generation portable neutron devices, for some specific applications, can constitute an alternative to existing large-scale neutron scattering facilities. Deuterium-Deuterium pulsed neutron sources able to generate 2.5MeV neutrons, with a neutron yield of 1.0×106n/s, a pulse rate of 250Hz to 20kHz and a duty factor varying from 5% to 100%, when combined with solid-state photon detectors, show that this kind of compact devices allow rapid and user-friendly elemental analysis. "This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo".


Subject(s)
Biophysics/methods , Neutron Activation Analysis/methods , Neutrons , Elements , Neutron Diffraction
4.
J Virol ; 88(23): 13910-7, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25231299

ABSTRACT

Extending our previous analyses to the most recently described monoclonal broadly neutralizing antibodies (bNAbs), we confirmed a drift of HIV-1 clade B variants over 2 decades toward higher resistance to bNAbs targeting almost all the identified gp120-neutralizing epitopes. In contrast, the sensitivity to bNAbs targeting the gp41 membrane-proximal external region remained stable, suggesting a selective pressure on gp120 preferentially. Despite this evolution, selected combinations of bNAbs remain capable of neutralizing efficiently most of the circulating variants.


Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Genetic Drift , HIV Antibodies/immunology , HIV Envelope Protein gp120/immunology , HIV Infections/immunology , HIV-1/immunology , Animals , Epidemics , HIV Envelope Protein gp120/genetics , HIV Envelope Protein gp41/genetics , HIV Envelope Protein gp41/immunology , HIV Infections/epidemiology , HIV Infections/virology , HIV-1/genetics , HIV-1/isolation & purification , Humans , Male , Mice , Neutralization Tests
5.
Mol Biol (Mosk) ; 49(6): 1041-7, 2015.
Article in Russian | MEDLINE | ID: mdl-26710788

ABSTRACT

Bacterial ribonucleases (RNases) are considered to be potential anticancer agents. One of most important determinants of RNase cytotoxicity is the net charge of the molecule. In this work a set of mutants of the RNase from Streptomyces aureofaciens (RNase Sa), differing in the net charge of the protein molecules (from -7 to +6) and localization of additional positive charge at the N- or C-terminus of the molecule is used to study inhibition of cell growth. It has been found that the mutants of RNase with increased cationicity most effectively inhibit the growth of HEKhSK4 cells. Additional positive charge at the C-terminus of the molecule also increases the cytotoxic properties of RNases. It has been shown that RNase cytotoxicity correlated with the level of inhibition of the K+-current in cells.


Subject(s)
Mutation , Potassium/metabolism , Ribonucleases/toxicity , Small-Conductance Calcium-Activated Potassium Channels/metabolism , Cell Survival/drug effects , HEK293 Cells , Humans , Ion Transport , Protein Structure, Tertiary , Ribonucleases/chemistry , Ribonucleases/genetics , Static Electricity , Streptomyces aureofaciens/enzymology
6.
J Fish Biol ; 84(3): 639-60, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24502775

ABSTRACT

While emergent behaviours have long been reported for air-breathing osteichthyians, only recently have researchers undertaken quantitative analyses of terrestrial locomotion. This review summarizes studies of sustained periodic terrestrial movements by air-breathing fishes and quantifies the contributions of the paired appendages and the axial body to forward propulsion. Elongate fishes with axial-based locomotion, e.g. the ropefish Erpetoichthys calabaricus, generate an anterior-to-posterior wave of undulation that travels down the axial musculoskeletal system and pushes the body against the substratum at multiple points. In contrast, appendage-based locomotors, e.g. the barred mudskipper Periophthalmus argentilineatus, produce no axial bending during sustained locomotion, but instead use repeated protraction-retraction cycles of the pectoral fins to elevate the centre of mass and propel the entire body anteriorly. Fishes that use an axial-appendage-based mechanism, e.g. walking catfishes Clarias spp., produce side-to-side, whole-body bending in co-ordination with protraction-retraction cycles of the pectoral fins. Once the body is maximally bent to one side, the tail is pressed against the substratum and drawn back through the mid-sagittal plane, which elevates the centre of mass and rotates it about a fulcrum formed by the pectoral fin and the ground. Although appendage-based terrestrial locomotion appears to be rare in osteichthyians, many different species appear to have converged upon functionally similar axial-based and axial-appendage-based movements. Based on common forms observed across divergent taxa, it appears that dorsoventral compression of the body, elongation of the axial skeleton or the presence of robust pectoral fins can facilitate effective terrestrial movement by air-breathing fishes.


Subject(s)
Fishes/physiology , Locomotion/physiology , Respiration , Air , Animals , Biomechanical Phenomena , Fishes/anatomy & histology
7.
New Phytol ; 197(1): 238-250, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23057437

ABSTRACT

A large database of invasive forest pathogens (IFPs) was developed to investigate the patterns and determinants of invasion in Europe. Detailed taxonomic and biological information on the invasive species was combined with country-specific data on land use, climate, and the time since invasion to identify the determinants of invasiveness, and to differentiate the class of environments which share territorial and climate features associated with a susceptibility to invasion. IFPs increased exponentially in the last four decades. Until 1919, IFPs already present moved across Europe. Then, new IFPs were introduced mainly from North America, and recently from Asia. Hybrid pathogens also appeared. Countries with a wider range of environments, higher human impact or international trade hosted more IFPs. Rainfall influenced the diffusion rates. Environmental conditions of the new and original ranges and systematic and ecological attributes affected invasiveness. Further spread of established IFPs is expected in countries that have experienced commercial isolation in the recent past. Densely populated countries with high environmental diversity may be the weakest links in attempts to prevent new arrivals. Tight coordination of actions against new arrivals is needed. Eradication seems impossible, and prevention seems the only reliable measure, although this will be difficult in the face of global mobility.


Subject(s)
Databases, Factual , Fungi/pathogenicity , Introduced Species , Trees/microbiology , Climate , Ecosystem , Europe , Fungi/classification , Fungi/physiology , Geography , Linear Models , Plant Diseases/microbiology , Population Density , Principal Component Analysis , Rain , Socioeconomic Factors , Temperature , Time Factors , Trees/physiology
8.
Front Psychol ; 14: 1284991, 2023.
Article in English | MEDLINE | ID: mdl-38250121

ABSTRACT

Background: Gender euphoria (i.e., a positive feeling associated with one's gender identity, expression, or affirmation) is widely discussed among transgender and gender diverse (hereafter referred to as trans) individuals. However, as a construct, gender euphoria has never been formally measured and has rarely been empirically studied. Hence, this protocol paper illustrates our process for developing and validating a new tool to measure gender euphoria, known as the Gender Euphoria Scale (GES), for use with trans populations. Methods: Deductive methods including findings from previous research and a review of existing measures, together with inductive methods such as expert feedback and focus groups with trans individuals, were used to generate a preliminary item pool for the GES. Pilot testing with trans community members and mental health clinicians was then used to refine items and develop a preliminary scale. Trans participants involved in an ongoing longitudinal study (TRANSform) were invited to complete the scale alongside measures of personality and gender factors to assess validity. Participants were then invited to complete the scale two weeks after initial completion to assess the test-retest reliability of the scale. The next stage in the scale development process will be to examine the dimensionality of the GES using exploratory factor analytic techniques. The scale will then be assessed for internal consistency, temporal stability, discriminant validity, and convergent validity. Conclusion: This paper outlines the development and characterization of a novel tool to measure gender euphoria for the first time. The GES will facilitate research opportunities to better understand the nature of gender euphoria and its influences, and may be used clinically to examine relationships between gender euphoria and gender affirming interventions. Hence, we expect the GES to make a significant contribution to both research and clinical practice with trans communities.

9.
Biophys J ; 102(8): 1907-15, 2012 Apr 18.
Article in English | MEDLINE | ID: mdl-22768947

ABSTRACT

Protein solubility is a problem for many protein chemists, including structural biologists and developers of protein pharmaceuticals. Knowledge about how intrinsic factors influence solubility is limited due to the difficulty of obtaining quantitative solubility measurements. Solubility measurements in buffer alone are difficult to reproduce, because gels or supersaturated solutions often form, making it impossible to determine solubility values for many proteins. Protein precipitants can be used to obtain comparative solubility measurements and, in some cases, estimations of solubility in buffer alone. Protein precipitants fall into three broad classes: salts, long-chain polymers, and organic solvents. Here, we compare the use of representatives from two classes of precipitants, ammonium sulfate and polyethylene glycol 8000, by measuring the solubility of seven proteins. We find that increased negative surface charge correlates strongly with increased protein solubility and may be due to strong binding of water by the acidic amino acids. We also find that the solubility results obtained for the two different precipitants agree closely with each other, suggesting that the two precipitants probe similar properties that are relevant to solubility in buffer alone.


Subject(s)
Proteins/chemistry , Ammonium Sulfate/chemistry , Animals , Humans , Polyethylene Glycols/chemistry , Protein Stability , Solubility , Surface Properties
10.
Cytogenet Genome Res ; 136(1): 75-81, 2012.
Article in English | MEDLINE | ID: mdl-22104134

ABSTRACT

Cytogenetic and DNA molecular analyses have been carried out in 3 wheat introgression lines (ILs; CS×V58, CS×V59, and CS×V60) derived from Triticum aestivum cv. 'Chinese Spring' (CS) × Dasypyrum villosum(Dv) intergeneric hybridization. All lines, which showed several phenotypic differences compared to CS, had the same chromosome number (2n = 42) and structure as CS, and neither chromosomes nor chromatin from Dv were apparently added to their complement. However, Feulgen/DNA cytophotometry showed that there was more nuclear DNA in the lines than in the parental wheat (by 1.85%, 2.76%, and 1.26% in CS×V58, CS×V59, and CS×V60, respectively). Molecular investigation indicated the presence of Dv DNA in the ILs. AFLP analysis of genomic DNA from the ILs, CS, and Dv detected a total of 120 polymorphic bands, of which 7 (5.8%) were present in some or all the ILs and Dv but were absent in CS. PCR amplification, sequence analysis of amplicons, and Southern blot hybridization confirmed the presence of Dv-specific sequences in each of the ILs. These results indicate cryptic introgression of Dv DNA sequences into the genome of the ILs. Some implications of this finding are discussed.


Subject(s)
Chromosomes, Plant , DNA, Plant/genetics , Genome, Plant , Hybridization, Genetic , Triticum/genetics , Cytogenetics/methods , Phenotype , Sequence Analysis, DNA/methods
11.
Attach Hum Dev ; 14(1): 45-61, 2012 Jan.
Article in English | MEDLINE | ID: mdl-22191606

ABSTRACT

This study analysed the attachment patterns of 28 late-adopted children (placed when they were between four and seven years of age) and their adoptive mothers. The change in the children's internal working models (IWMs) within seven to eight months of their placement was evaluated. In addition, we wanted to observe the influence of a secure-autonomous maternal state of mind in facilitating the change in the children's IWMs and the possible associations between the maternal IWMs and the children's IWMs in the adoptive dyads. The separation-reunion procedure (SRP) was used for the late-adopted children in order to assess their attachment behavioural patterns, and the Manchester Child Attachment Story Task (MCAST) was used to evaluate their attachment narrative patterns. The adoptive mothers completed the Adult Attachment Interview (AAI) in order to classify their state of mind with regard to attachment. The results showed a significant change in the attachment behavioural patterns of late-adopted children, from insecure to secure (p = .002). Furthermore, the children who presented this change were predominantly placed with secure-autonomous adoptive mothers (p = .047), although the link between the adoptive mothers' representations of their attachment history and their adopted children's completed narratives was not significant. In conclusion, it seems possible to revise the attachment behaviour of late-adopted children but, for about one-third of children, the adverse history will persist at a narrative/representational level.


Subject(s)
Adoption/psychology , Child Behavior , Maternal Behavior , Mother-Child Relations , Object Attachment , Adult , Child , Child Development , Child, Preschool , Female , Humans , Italy , Longitudinal Studies , Male , Middle Aged , Personality Development , Pilot Projects
12.
Child Care Health Dev ; 37(1): 82-8, 2011 Jan.
Article in English | MEDLINE | ID: mdl-20637017

ABSTRACT

OBJECTIVE: This study examined the attachment patterns of late-adopted children (aged 4-7) and their adoptive mothers during the first 7- to 8-month period after adoption and aimed to evaluate the effect of adoptive mothers' attachment security on the revision of the attachment patterns of their late-adopted children. DESIGN: We assessed attachment patterns in 20 adoptive dyads and 12 genetically related dyads at two different times: T1 (time 1) within 2 months of adoption and T2 (time 2) 6 months after T1. METHODS: The children's behavioural attachment patterns were assessed using the Separation-Reunion Procedure and the children's representational (verbal) attachment patterns using the Manchester Child Attachment Story Task. The attachment models of the adoptive mothers were classified using the Adult Attachment Interview. RESULTS: We found that there was a significant enhancement of the late-adopted children's attachment security across the time period considered (P= 0.008). Moreover, all the late-adopted children who showed a change from insecurity to security had adoptive mothers with secure attachment models (P= 0.044). However, the matching between maternal attachment models and late-adopted children's attachment patterns (behaviours and representations) was not significant. CONCLUSIONS: Our data suggest that revision of the attachment patterns in the late-adopted children is possible but gradual, and that the adoptive mothers' attachment security makes it more likely to occur.


Subject(s)
Adoption/psychology , Mother-Child Relations , Mothers/psychology , Object Attachment , Adult , Age Factors , Case-Control Studies , Child , Child, Preschool , Female , Humans , Male , Middle Aged , Personality Assessment , Personality Development , Pilot Projects , Time Factors
13.
Pediatr Med Chir ; 32(5): 220-2, 2010.
Article in English | MEDLINE | ID: mdl-21171521

ABSTRACT

Spontaneous aneurysms of the ductus arteriosus are rare complications of a patent ductus arteriosus. It is met at any age but it is most commonly seen in children under two months of age. Echocardiography is the best test to diagnose a ductus arteriosus, but actually the role of thoracoscopy is to help in differential diagnosis of mediastinal masses. Surgery should be recommended without delay, to avoid fatal complications, with the resection of the thrombosed aneurysm of the ductus arteriosus.


Subject(s)
Ductus Arteriosus , Heart Aneurysm/complications , Heart Diseases , Thrombosis , Age Factors , Diagnosis, Differential , Heart Aneurysm/diagnosis , Heart Aneurysm/diagnostic imaging , Heart Aneurysm/surgery , Heart Diseases/diagnosis , Heart Diseases/diagnostic imaging , Heart Diseases/pathology , Heart Diseases/surgery , Humans , Infant, Newborn , Magnetic Resonance Imaging , Male , Thoracoscopy , Thrombosis/diagnosis , Thrombosis/diagnostic imaging , Thrombosis/pathology , Thrombosis/surgery , Tomography, X-Ray Computed
14.
Radiol Case Rep ; 15(1): 54-58, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31737147

ABSTRACT

We describe a case of 85-year-old man who presented to the Emergency Department with sudden dyspnea. He had a past medical history of cardiomyopathy and radiography and nonenhanced computed tomography (CT) of the chest showed pulmonary edema. Despite intravenous diuretic therapy, there was no clinical improvement. Cardiac CT was then performed showing a solid pulmonary nodular lesion with intralesional cavitations, ground-glass opacities, and peripheral vascularization. CT-guided needle lung biopsy yielded a diagnosis of granulomatosis with polyangiitis (Wegener granulomatosis). Medical treatment with cyclophosphamide and prednisone produced rapid symptomatic improvement and complete resolution of the radiological findings. This case demonstrates the challenges in making this diagnosis in an elderly patient with heart disease. We found very few documented cases where there was onset of granulomatosis with polyangiitis at this age.

15.
Proteins ; 77(3): 491-8, 2009 Nov 15.
Article in English | MEDLINE | ID: mdl-19626709

ABSTRACT

Our goal was to gain a better understanding of how protein stability can be increased by improving beta-turns. We studied 22 beta-turns in nine proteins with 66-370 residues by replacing other residues with proline and glycine and measuring the stability. These two residues are statistically preferred in some beta-turn positions. We studied: Cold shock protein B (CspB), Histidine-containing phosphocarrier protein, Ubiquitin, Ribonucleases Sa2, Sa3, T1, and HI, Tryptophan synthetase alpha-subunit, and Maltose binding protein. Of the 15 single proline mutations, 11 increased stability (Average = 0.8 +/- 0.3; Range = 0.3-1.5 kcal/mol), and the stabilizing effect of double proline mutants was additive. On the basis of this and our previous work, we conclude that proteins can generally be stabilized by replacing nonproline residues with proline residues at the i + 1 position of Type I and II beta-turns and at the i position in Type II beta-turns. Other turn positions can sometimes be used if the phi angle is near -60 degrees for the residue replaced. It is important that the side chain of the residue replaced is less than 50% buried. Identical substitutions in beta-turns in related proteins give similar results. Proline substitutions increase stability mainly by decreasing the entropy of the denatured state. In contrast, the large, diverse group of proteins considered here had almost no residues in beta-turns that could be replaced by Gly to increase protein stability. Improving beta-turns by substituting Pro residues is a generally useful way of increasing protein stability.


Subject(s)
Proteins/chemistry , Biochemistry/methods , Glycine/chemistry , Histidine/chemistry , Molecular Conformation , Mutation , Plasmids/metabolism , Proline/chemistry , Protein Conformation , Protein Denaturation , Protein Folding , Protein Stability , Protein Structure, Secondary
16.
Am J Transplant ; 9(4): 675-86, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19298452

ABSTRACT

An important role of TNF interacting with TNFR2 has been shown in different models of ischemic, nephrotoxic and immune-mediated renal injury. To systematically evaluate the expression of TNFR2 in renal allograft rejection, we investigated human renal allograft biopsies and, in addition, established an experimental transplantation model in rats to verify the human data under standardized conditions. The expression of TNFR2 was analyzed in 96 human renal allograft biopsies with different disease entities. In a 6-day and a 28-day experimental protocol, TNFR2 was examined in kidney specimens and in the urine of control, uni-nephrectomized and transplanted rats +/- cyclosporine treatment (n = 114). In human biopsies and in rat allografts on day 6 with acute allograft rejection, significantly elevated expression of TNFR2 was observed in tubular epithelial cells, podocytes, B cells and monocytes/macrophages. The expression level was associated with renal function. The TNFR2 expression level at day 28 was significantly lower compared to day 6. TNFR2 is markedly upregulated both in human and experimental acute renal allograft rejection. Our data are robust and consistent between different species, suggesting a role for TNFR2 in the early course of rejection.


Subject(s)
Gene Expression Regulation , Graft Rejection/genetics , Kidney Transplantation/pathology , Receptors, Tumor Necrosis Factor, Type II/genetics , Adult , Aged , Animals , Biopsy , Cyclosporine/therapeutic use , Female , Humans , Immunosuppressive Agents/therapeutic use , Male , Middle Aged , Models, Animal , Rats , Receptors, Tumor Necrosis Factor, Type I/physiology , Transplantation, Homologous/pathology , Up-Regulation
17.
J Cell Biol ; 85(2): 392-401, 1980 May.
Article in English | MEDLINE | ID: mdl-7372713

ABSTRACT

Cells in isolated rabbit gastric gland were made permeable to ATP by high voltage discharge across a gland suspension. In both normal (5.4 mM K+) and high K+ (108 mM) medium, this electrical shock resulted in a marked reduction in the ability of the parietal cell to produce and accumulate acid. Acid production was monitored both microscopically by acridine orange accumulation in the secretory canaliculus and by accumulation of the weak base [14C]aminopyrine. In 108 mM K+ solutions but not in 5.4 mM K+ solutions 5, mM ATP was able to restore the accumulation of these probes to control (unshocked) levels. When shocked glands had been previously stimulated by secretagogues, the aminopyrine accumulation ratio was only partly restored by ATP. Inhibition of mitochondrial respiration by cyanide, azide, or Amytal abolished acid secretion; the subsequent addition of ATP to shocked glands increased the aminopyrine accumulation ratio to 47 and resulted in an acridine orange fluorescence indistinguishable from that of histamine-stimulated, unshocked glands. We conclude that ATP can act as a substrate for H+ secretion in the parietal cell, and that perhaps no additional energy source is necessary.


Subject(s)
Adenosine Triphosphate/pharmacology , Exocrine Glands/metabolism , Gastric Juice/metabolism , Gastric Mucosa/metabolism , Aminopyrine/metabolism , Animals , Calcium/pharmacology , Cyanides/pharmacology , Exocrine Glands/drug effects , Kinetics , Mitochondria/metabolism , Models, Biological , Potassium/pharmacology , Rabbits
18.
Methods Mol Biol ; 490: 41-55, 2009.
Article in English | MEDLINE | ID: mdl-19157078

ABSTRACT

The stability of globular proteins is an important factor in determining their usefulness in basic research and medicine. A number of environmental factors contribute to the conformational stability of a protein, including pH, temperature, and ionic strength. In addition, variants of proteins may show remarkable differences in stability from their wild-type form. In this chapter, we describe the method and analysis of urea denaturation curves to determine the conformational stability of a protein. This involves relatively simple experiments that can be done in a typical biochemistry laboratory, especially when using ordinary spectroscopic techniques to follow unfolding.


Subject(s)
Protein Denaturation , Protein Folding , Proteins/chemistry , Urea/chemistry , Circular Dichroism , Protein Conformation
19.
Trends Biochem Sci ; 15(1): 14-7, 1990 Jan.
Article in English | MEDLINE | ID: mdl-2107612

ABSTRACT

The conformational stability of ribonuclease T1 has been measured as a function of the variables of most interest to biochemists: temperature, pH, salt concentration, disulfide-bond content and amino acid sequence. The results provide insight into the forces that stabilize globular proteins.


Subject(s)
Endoribonucleases , Protein Conformation , Ribonuclease T1 , Amino Acid Sequence , Isoelectric Point , Molecular Sequence Data , Thermodynamics
20.
Biophys J ; 94(6): 2288-96, 2008 Mar 15.
Article in English | MEDLINE | ID: mdl-18065473

ABSTRACT

Characterizing the denatured state ensemble is crucial to understanding protein stability and the mechanism of protein folding. The aim of this research was to see if fluorescence could be used to gain new information on the denatured state ensemble. Ribonuclease Sa (RNase Sa) contains no Trp residues. We made five variants of RNase Sa by adding Trp residues at locations where they are found in other members of the microbial ribonuclease family. To better understand the protein denatured state, we also studied the fluorescence properties of the following peptides: N-acetyl-Trp-amide (NATA), N-acetyl-Ala-Trp-Ala-amide (AWA), N-acetyl-Ala-Ala-Trp-Ala-Ala-amide (AAWAA), and the five pentapeptides with the same sequence as the Trp substitution sites in RNase Sa. The major conclusions are: 1), the wavelength of maximum fluorescence intensity, lambda(max), does not differ significantly for the peptides and the denatured proteins; 2), the fluorescence intensity at lambda(max), I(F), differs significantly for the five Trp containing variants of RNase Sa; 3), the I(F) differences for the denatured proteins are mirrored in the peptides, showing that the short-range effects giving rise to the I(F) differences in the peptides are also present in the proteins; 4) the I(F) values for the denatured proteins are more than 30% greater than for the peptides, showing the presence of long-range effects in the proteins; 5), fluorescence quenching of Trp by acrylamide and iodide is more than 50% greater in the peptides than in the denatured proteins, showing that long-range effects limit the accessibility of the quenchers to the Trp side chains in the proteins; and 6), these results show that nonlocal effects in the denatured states of proteins influence Trp fluorescence and accessibility significantly.


Subject(s)
Ribonucleases/chemistry , Spectrometry, Fluorescence/methods , Urea/chemistry , Acrylamide/chemistry , Acrylamides/chemistry , Amino Acid Sequence , Disulfides/chemistry , Fluorescence , Iodides/chemistry , Molecular Conformation , Molecular Sequence Data , Peptides/chemistry , Proteins/chemistry , Time Factors , Tryptophan
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