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At least 181 records · Page 10Linked to original sources
PubMed1993

Specific atrial overexpression of G protein coupled human beta 1 adrenoceptors in transgenic mice.

OBJECTIVE: The aim was to develop a transgenic mouse model of atrial beta 1 adrenoceptor overexpression in order to create atrial alteration of the receptor transduction system. METHODS: Transgenic founders were generated after microinjection of the transgene construct into the pronucleus of fertilised mouse eggs. Heterozygous progeny were screened for RNA expression of the human beta 1 adrenoceptor gene under the control of a 0.56 kb proximal promoter of the human atrial natriuretic factor. One line, out of the three obtained, was selected and further characterised for overexpression of the human beta 1 adrenoceptor. Polymerase chain reaction was employed to detect beta 1 adrenoceptor mRNA, and 125I-cyanopindolol (ICYP) binding assays were used to quantify receptors in heart membranes. A quantitative autoradiographic ICYP binding technique was also used to visualise atrial and ventricular beta adrenoceptors in heart sections. RESULTS: The human beta 1 adrenoceptor was overexpressed specifically in the atria of transgenic mice. The level of the beta 1 adrenoceptor was 5-10-fold higher in transgenic mice compared to basal murine beta 1 adrenoceptors in non-transgenic control mice. Left and right atrial receptor overexpression was confirmed by in vitro autoradiography. The human receptors were able to couple to the murine stimulatory G proteins (Gs), as shown by high affinity binding site dosage using the beta adrenoceptor agonist isoprenaline. Isoprenaline displacement studies allowed the determination of two different affinity sites, one of high affinity (KH = 5.8 nM), and one of low affinity (KL = 520 nM). When expressed in terms of protein density (fmol.mg-1), atrial transgenic beta 1 adrenoceptors displayed a threefold increase in high affinity sites (KH) as compared to control mice. Preliminary electrocardiographic data showed supraventricular premature beats in 6/14 transgenic mice v 2/16 control mice. CONCLUSIONS: These transgenic mice may provide a useful pharmacological tool to investigate the pathophysiological consequences of the overactivation of atrial beta 1 adrenoceptor-adenylyl cyclase signalling system.

Animals↗
PubMed1988

The major protein of bull seminal plasma: biosynthesis and biological function.

We isolated the major protein of apparent Mr of 15,000-16,000 from seminal plasma as well as from seminal vesicle secretion of bull and proved by amino acid analysis and tryptic peptide mapping that the two proteins were identical. An antiserum against this major protein was employed to quantitate and identify the major protein in seminal plasma as well as seminal vesicle secretion. The antiserum did not cross-react with proteins from bovine or human plasma or follicular fluid respectively. Cell-free translation of poly(A)RNA from seminal vesicle tissue and immunoprecipitation yielded one major species with apparent Mr of 18,000. Using the anti-major protein antiserum, this major species was specifically immuno absorbed. Cloning and sequencing of a major protein-specific cDNA led to the identification of clone pMP17, encoding a precursor of the major protein of 128 amino acid residues. We proved that the major protein is identical to protein PDC 109 (Esch et al., Biochem. Biophys. Res. Comm. 113:861-867, 1983). The seminal vesicles synthesize major protein in an androgen-dependent fashion. In addition to intraluminal secretion of the vas deferens, ampullary spermatozoa revealed an intense immunoreaction which was restricted to the neck region of the sperm head and the middle piece, while the principal piece of the tail as well as the sperm head were devoid of immunoreactive material. Epididymal epithelium (as well as calf seminal vesicle epithelium) showed no immunoreactivity with major protein antiserum. Immunoelectron microscopy demonstrated that only spermatozoa devoid of a plasma membrane around the middle piece were able to bind the antiserum against major protein. After removal of the plasma membrane from epididymal spermatozoa, binding of major protein to subplasmalemmal binding sites was visualised using gold-labeled MP. Transblotting with gold-labeled MP demonstrated a protein of about 66 kDa which appears to represent the major protein-receptor. Binding of major protein to the receptor (after loss of the plasma membrane in the mid-piece region of the spermatozoa after contact with secretions from seminal vesicles) is interpreted as a physiological process presumably related to the onset of sperm motility.

Amino Acid Sequence↗
PubMed1994

Molecular dynamics simulations of oligonucleotides in solution: visualization of intrinsic curvature.

We have undertaken molecular dynamics simulations on the d(CGCAAAAAAGCG).d(CGCTTTTTTGCG) dodecamer in solution. In this study, we focus on aspects of conformation and dynamics, including the possibility of cross-strand hydrogen bonds. We compare our results with those from crystallography as well as infrared, Raman and NMR spectroscopy and cyclization kinetics. Our method of analysis allows us to visualise the curvature of the helix as a function of time during the simulation. We find that the major distortions of the helix axis path occur at the junctions between the (essentially straight) A-tract and the CG- and GC-tracts, although at one junction this is due to hyperflexibility (i.e., regions of high flexibility with no preferred direction of curvature), while at the other junction a static curvature is found (i.e., a preferred, sustained direction of curvature).

Base Sequence↗
PubMed1986

Regulatory peptides of the gastrointestinal and respiratory tracts.

The gastrointestinal and respiratory tracts contain numerous regulatory peptides produced by and released from specialised epithelial cells and the organ innervation. This complex system of endocrine cells and nerves is generally called "the diffuse neuroendocrine system". Markers are now available which permit the visualisation of the diffuse neuroendocrine system or its individual components. These include antibodies to neuron-specific enolase, chromogranin, neurofilament triplet proteins, the brain protein S100 and antibodies to a variety of regulatory peptides. Peptides present in the gut and lung innervation include: vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), galanin, substance P, calcitonin gene-related peptide (CGRP), neuropeptide tyrosine (NPY), somatostatin and cholecystokinin (the latter two are also localised to endocrine cells of the gut). Bombesin-immunoreactivity is found in nerves in the gut and in endocrine cells of the foetal/neonatal lung. Neuropeptides of the gut and lung originate either from local neurons (e.g. VIP, PHI, galanin) or extrinsic neurons localised in sensory ganglia (e.g. substance P and CGRP) or the sympathetic chain (e.g. NPY). Recent studies point to the involvement of regulatory peptides in diseases of the gut and lung. These, together with detailed distribution studies, provide supportive data on the putative role of the peptides in the control of normal bowel and respiratory functions. The gastrointestinal and respiratory tracts were within the systems investigated by Feyrter during his original observations on the existence of specialised epithelial cells with a putative regulatory function (Feyrter, 1938). These "endocrine/paracrine" cells were found to be scattered in epithelial organs throughout the body. In fact, endocrine cells of the respiratory tract are frequently referred to as "Feyrter's cells". The term "regulatory peptides" was introduced as a generic term (Polak and Bloom, 1983) after the finding that active peptides are produced both by cells of the diffuse endocrine or APUD (amine precursor uptake and decarboxylation) system (Pearse, 1983) and autonomic/sensory nerves. These peptides are released into the circulation from endocrine cells or locally from nerve terminals or paracrine cells. The concept of "gut/brain" peptides was dispelled after the findings that the respiratory tract was provided abundantly with numerous active peptides produced by and released from mucosal endocrine cells and/or the innervation.

Animals↗
PubMed1995

How the horse moves: 1. Significance of graphical representations of equine forelimb kinematics.

The kinematics of 24 two-year-old Dutch Warmblood horses were recorded at the trot (4 m/s) on a high-speed treadmill to study the coordination of joints within the equine forelimb. Joint angle-time, angle-angle, stick, and marker diagrams were used to show forelimb motion graphically. Because the kinematic data referred to the joint angles of the horse standing squarely and were time-standardised to the duration of the stride cycle, mean joint curves could be calculated for the total group. The motion of each segment in the equine forelimb during a complete stride is described and its function in intralimb coordination evaluated. It appeared that the rotation of the scapula and the cranio-caudal movement of the distal forelimb are synchronous and pendular. The carpal joint rapidly snaps into overextension at the beginning of the stance phase to enable the forelimb to work as a propulsive strut. The fetlock joint acts as an elastic spring, thereby conserving energy and, at the same time, absorbs oscillations generated by initial ground contact. Furthermore, the coordination between carpal and fetlock joints in the swing phase appears to be strongly influenced by inertia. Using the graphic tools evaluated in this paper, we were able to visualise the kinematics of the equine forelimb and relate these to specific functions of the forelimb in locomotion. This information can be used to select kinematic variables for clinical studies in which equine forelimb function has to be described and quantified.

Animals↗
PubMed1995

Multiplex PCR for identifying mycobacterial isolates.

AIMS: To develop a multiplex polymerase chain reaction (PCR) method to facilitate identification of mycobacterial isolates. METHODS: Type strains of 14 species of mycobacteria and 56 clinical isolates were lysed by boiling in TE Triton. The lysate (5 microliters) was used directly in a PCR reaction incorporating three pairs of PCR primers expected to amplify fragments from the genome of (a) all mycobacteria, (b) Mycobacterium tuberculosis complex only and (c) M avium only. PCR products were visualised by electrophoresis on agarose gels. RESULTS: Multiplex PCR applied to 14 type strains yielded patterns on electrophoresis which permitted identification of the mycobacterial isolates as M tuberculosis complex, M avium or as mycobacteria other than the former. The identification of 56 clinical isolates by multiplex PCR was consistent with other methods and was accomplished in less than one working day. CONCLUSIONS: This method may facilitate rapid and convenient identification of most clinical isolates of mycobacteria by PCR and gel electrophoresis. Further evaluation is warranted.

Base Sequence↗
PubMed1994

Consideration of time-dose-patterns in 3D treatment planning. An approach towards 4D treatment planning.

PURPOSE: The rendering of the 3D dose distribution together with anatomical information and the volumes of interest (VoI) is essential to get a visual impression of the treatment plan and to find modifications for the optimization of the dose distribution. The integration of biological effects into the 3D treatment planning is of interest for the assessment of different time-dose patterns. MATERIALS AND METHODS: One way of taking into account biological data is to relate the physical dose in critical structures to the corresponding tolerance dose. For that purpose the applied time-dose pattern has to be converted into the standard fractionation scheme being the basis of the tolerance dose. Generally any model can be used for these calculations. Here a modified incomplete repair model is used to calculate the relative biological dose distribution (RBD). The visualization of these biologically isoeffective dose distributions can be performed in the same manner as the physical dose so that the physical and biological dose distributions can by displayed side by side. As this is equivalent to introducing the time as a fourth dimension into 3D treatment planning this is called 4D treatment planning. RESULTS: From 3D dose matrices the biologically isoeffective dose distributions are calculated for the organs at risk. The changes introduced by different time-dose patterns are displayed using the same technique as for rendering 3D treatment plans. The visualisation of the three-dimensional biological dose distributions is shown by means of a patient with an oesophagus carcinoma. The RBD related to the tolerance dose of the organs at risk is displayed for different time-dose fractionations. CONCLUSION: The RBD distribution on a 3D treatment plan can be displayed in the same mode as the physical dose distribution. This offers additionally valuable information in a 3D treatment planning process about the dose to critical organs and the influence of different time-dose patterns.

Color↗
PubMed1992

Immunoperoxidase labelling of albumin at the endothelial cell surface of frog mesenteric microvessels.

Albumin was visualised at the endothelial cell surface of perfused frog mesenteric microvessels using immuno-peroxidase labelling. Vessels in the mesenteries of pithed frogs were washed free of blood and then perfused with frog Ringer solutions containing bovine serum albumin (BSA) at a concentration of 20 mg BSA ml-1, followed by a brief Ringer flush to remove excess albumin from the vessel lumen. The tissues were fixed in 1% glutaraldehyde and a double antibody labelling technique used to identify albumin within the tissue. A dense layer of peroxidase reaction product was seen, which extended 25-50 nm into the vessel lumen. It appeared as a continuous layer lining the luminal openings of interendothelial cell clefts and vesicles open to the luminal cell surface. In some vessels a more irregular layer of peroxidase labelled albumin was seen extending 150 to 200 nm into the vessel lumen, whilst in others clumps of peroxidase labelled albumin were also seen within the vessel lumen. These data offer direct evidence that BSA does interact with the endothelial cell surface of perfused frog mesenteric microvessels but suggest that a proportion is loosley or non-specifically bound to the cell surface and can be removed by a brief Ringer flush. The remainder appears more tightly bound and resistant to Ringer flush.

Animals↗
PubMed1995

[2-dimensional mapping and retinal and papillary microcirculation using scanning laser Doppler flowmetry].

PURPOSE: To present clinical applications of a new non-invasive method imaging in a high-definition the topography of perfused retinal vessels. METHOD: By a combination of a laser Doppler flowmeter with a scanning laser system the perfusion of the retina and the optic nerve head is visualized and quantified. The principles of measuring blood flow by Laser Doppler Flowmetry are based on the optical Doppler effect: laser light scattered by a moving particle is shifted in frequency by an amount delta f. Our data acquisition and evaluation system is a modified laser scanning tomograph. The technical data are: retinal area of measurement 2.7 mm x 0.7 mm, 10 degree-field with 256 points x 64 lines, measurement accuracy 10 microns, wavelength 670 nm and 790 nm, light power 100 microW, data acquisition time 2,048 s. Every line is scanned 128 times by a line-sampling rate of 4,000 Hz. By performing a discrete Fast Fourier Transformation over 128 intensities of each retinal point the laser Doppler-shift is calculated for each retinal point. With these data a 2-D map with 256 x 64 points of the retinal perfusion is created. The brightness of the picture-point is coded by the value of the Doppler shift. We estimated the reliability and the validity of the method. Perfusion-pictures of the superficial retinal layer and in the optic nerve head were presented. RESULTS: The reliability-coefficients r1 of "Flow", "Volume" and "Velocity" were 0.85, 0.83, and 0.85 respectively. The blood flow measurements by the presented method ("Scanning Laser Doppler Flowmetry") in an artificial capillary gave a linear relationship (r-value 0.973, p < 0.00001) between defined blood velocities and the measured blood flow. By the confocal technique, dependent on the focus, capillaries of the retinal superficial vasculature of the optic nerve head became visible with a high resolution. Off line the blood flow of areas of 110 microns x 110 microns were calculated in terms of laser Doppler flowmetry. CONCLUSION: "Scanning Laser Doppler Flowmetry" facilitates the visualisation of perfused retinal capillaries and vessels in high resolution. The representation of the function of the retinal circulation by SLDF leads to an image similar to the anatomical situation. The 2-dimensional mapping of local blood flow leads to a physiological picture of the retinal perfusion with visible vessels and capillaries.

Adult↗
PubMed1994

Visualisation by electron microscopy of the unique part of the cytoplasmic domain of a desmoglein, a cadherin-like protein of the desmosome type of cell junction.

Part of the cytoplasmic domain of a human desmoglein, Dsg1, a cadherin-like protein found in desmosomes of epithelial cells, has been visualised by electron microscopy. The cloned fragment contains five repeats of a 29 +/- 4 residue sequence unique to desmogleins, followed by a glycine-rich region. In rotary shadowed preparations the molecule consists of a globular head attached to a thin tail, the latter perhaps corresponding to the glycine-rich region. This portion of the molecule is thought to span the width of the inner dense plaque. The structure and dimensions concur well to the configuration deduced from the protein sequence.

Amino Acid Sequence↗
PubMed1991

Visualisation and measurement of the calcium message in guard cells.

We have applied several novel technologies to investigate the role of cytosolic free calcium [Ca2+]i in signal transduction in guard cells of Commelina communis L. Fluorescence ratio imaging and photometry together with the fluorescent Ca2+ indicator Indo-1 were used to directly visualise and measure dynamic spatial and temporal changes in [Ca2+]i in response to various exogenous stimuli. More subtle manipulation of the Ca2+ signal transduction pathway was achieved through the use of photoactivateable, caged Ca2+ and caged inositol-1,4,5-triphosphate (InsP3) released directly into the cytoplasm of the guard cell after microinjection. In these experiments, changes in [Ca2+]i were simultaneously monitored with the fluorescent Ca2+ indicator, Fluo-3. Resting levels of [Ca2+]i (100-200 nM) increased in response to elevated [Ca2+]e, lowering [K+]e, application of the ionophore A-23187 or cytosolic release of either Ca2+ or InsP3 from their caged forms. Stomatal closure was triggered if [Ca2+]i increased above a threshold of about 600 nM. Abscisic acid (ABA) had little effect on [Ca2+]i in the majority of cells studied, being elevated in only a minority of cells investigated. However, stomatal closure occurred in all cases after ABA application. This suggests that ABA acts through both Ca(2+)-independent and Ca(2+)-dependent pathways. The imaging data revealed a substantial heterogeneity in [Ca2+]i within the guard cell. Cytoplasmic regions, particularly near the nucleus, often showed marked elevations and sometimes oscillations. The origin and kinetics of the Ca2+ fluxes leading to the dynamic spatial patterns is discussed along with several new approaches directed towards identification of the source of the Ca2+. These methods include optical sectioning and 3-D reconstruction of both the endomembrane system and [Ca2+]i in living guard cells using confocal microscopy. Overall, our data is consistent with multiple sources for [Ca2+]i, including uptake across the plasma membrane and InsP3- or Ca(2+)-induced Ca2+ release from internal stores.

Calcium↗
PubMed1995

Detection of maternal cell contamination in amniotic fluid cell cultures using fluorescent labelled microsatellites.

A rapid PCR based assay was used to ascertain the presence of maternal cell contamination (MCC) in amniotic fluid cell cultures and to exclude MCC in cases where cytogenetic analysis was possible only from one primary cell culture. Six 6-carboxyfluorescein (FAM) and three 6-carboxyfluorescein hexachloride (HEX) labelled primer sets were used to amplify two tetra- and seven dinucleotide repeat polymorphisms. The PCR amplifications were multiplexed in (three) three primer set reactions and visualised on an Applied Biosystems 373A sequencer running Genescan 672 software. The microsatellite products obtained from 200 amniotic fluid cell cultures where the karyotype was female were compared against corresponding maternal blood PCR products. A single case of MCC was detected indicating the usefulness of such assays. We suggest that screening for MCC should be considered in instances where the amniotic fluid sample is bloodstained or was obtained with difficulty, or where the karyotype is female and chromosome analysis is not possible from more than one primary cell culture.

Amniocentesis↗
PubMed1994

Bilirubin, ferritin, D-dimers and erythrophages in the cerebrospinal fluid of patients with suspected subarachnoid haemorrhage but negative computed tomography scans.

AIM: To assess the diagnostic value of cerebrospinal fluid (CSF) spectrophotometry, cytology, ferritin, and D-dimer measurements in the investigation of suspected subarachnoid haemorrhage in patients with negative or equivocal computed tomography (CT) scans. METHODS: CSF specimens submitted for assessment of xanthochromia were examined for erythrophages using a cytospin preparation stained with Wright's stain, for ferritin using the Ciba-Corning Magic IRMA assay, D-dimers using the Dimertest 2 latex agglutination slide test, and for bilirubin by scanning spectrophotometry. The patients were divided into three groups for data analysis and the results compared with the existing methods, CT, and angiogram results. Final diagnoses were reviewed by a consultant neurologist. RESULTS: Thirty six patients were recruited. In those patients with confirmed subarachnoid haemorrhage CSF cytology had a low sensitivity and there were false negative results with both the D-dimer and ferritin assays. Eleven patients with a negative or equivocal CT scan underwent angiography, but only one aneurysm and no arterio-venous malformations or bleeding points were identified. In the patient with the aneurysm there was no laboratory evidence of subarachnoid haemorrhage. Six patients had CSF abnormalities detected by the special tests only and in none of these cases was subarachnoid haemorrhage confirmed. All results were normal in four out of five cases of traumatic tap. CONCLUSIONS: This is a small study, but it shows that, depending on the timing of the lumbar puncture, false negative results can occur with both ferritin and D-dimer measurements. It suggests that neither of these tests adds significantly to the information provided by CT, visualisation of CSF, and spectrophotometry and confirms that, despite the use of spectrophotometry, D-dimer and ferritin assays in selecting patients for angiography, the proportion of patients with negative CT scans and colourless CSF with demonstrable vascular lesions remains low.

Bilirubin↗
PubMed1995

Multi-dimensional visualisation of laboratory findings and functional test results for analysing the clinical course of disease in medicine.

The illustration of a patient's history by a graphical primitive is discussed. Illustration technology is presented which simultaneously represents quantitative examination findings (e.g., laboratory values) and qualitative findings (e.g., from function diagnostics) by a single geometrical figure. Depending on the medical results, this figure takes on characteristic forms which can be identified as patterns typical for a specific disease. The procedure developed is integrated in a user interface which is implemented in the form of a computerized medical record for use on a pentop computer. This portable computer assists the physician during ward rounds, supplies additional, intelligence-based information, serves quality control, and streamlines working procedures making them more efficient.

Clinical Laboratory Information Systems↗
PubMed1981

The role of two-dimensional echocardiography in the detection of potentially embolic intracardiac masses in patients with cerebral ischaemia.

The M-mode and two dimensional echocardiographic data of 62 consecutive cardiac patients referred from neurology centres were analysed retrospectively to establish the use of these techniques in detecting underlying cardiac pathology. All patients had presented initially to a neurologist with transient or permanent focal cerebral or retinal ischaemia, and had been referred for cardiac assessment after neurological investigations failed to establish the underlying cause of the neurological event. Patients were divided into two groups. In 30 patients the referring neurologist had found no evidence of cardiac disease (Group I); in the other 32 patients either heart disease or an arrhythmia had been diagnosed prior to cardiac referral (Group II). One of the patients in Group I had echocardiographic evidence of mitral valve prolapse not detected by the neurologist prior to referral; no cardiac pathology was recognised in the other 29 patients in this group. In seven of the 32 (22%) patients from Group II, a cardiac mass presumed responsible for the neurological manifestations was demonstrated echocardiographically, and in six of these histological confirmation was obtained following surgery or at necropsy. Two dimensional echocardiography was the only investigation which visualised the intracardiac pathology in four patients. In the remaining three patients, valve vegetations (two cases) and an atrial tumour (one case) were demonstrated by both echocardiographic methods. In patients with either clinical evidence of cardiac disease or an arrhythmia who have experienced one or more episodes of cerebral or retinal ischaemia, the presence of an intracardiac mass is not uncommon. Two dimensional echocardiography was the method of choice for detecting cardiac thrombus but the use of both methods of ultrasound should be considered as complementary techniques in the investigation of these cases. Routine echocardiography is unlikely to be of value in screening patients who have had a cerebrovascular event and who do not have clinical evidence of heart disease or an arrhythmia.

Adolescent↗
PubMed1992

Immunocytochemical identification of oestrogen receptors in preoptic neurones containing calcitonin gene-related peptide in the male and female rat.

Using single- and double-labelling immunocytochemistry with antibodies specific for the oestrogen receptor and calcitonin gene-related peptide (CGRP), we have demonstrated oestrogen receptor immunoreactivity in the sexually dimorphic CGRP-immunoreactive (IR) population of the medial preoptic area (MPOA). In the short-term gonadectomised female approximately 80% of preoptic CGRP-IR neurones were immunoreactive for the oestrogen receptor. In short-term gonadectomised males, a small population of CGRP-IR cells was visualised in the MPOA only after colchicine treatment. Approximately 30% of CGRP-IR cells in the male were oestrogen receptor-IR, accounting for 2% of the total population of cells containing oestrogen receptors in this area. In the colchicine-treated female, it is estimated that 10-15% of preoptic oestrogen receptor-IR cells contain CGRP. These results indicate that CGRP is synthesised by preoptic neurones with oestrogen receptors. Furthermore, the identification of oestrogen receptors in the sexually dimorphic CGRP population suggests that these neurones may be directly linked with gonadal steroid-dependent, sex-specific functioning of the MPOA.

Animals↗
PubMed1994

A study of the interaction of DAPI with DNA containing AT and non-AT sequences--molecular specificity of minor groove binding drugs.

The binding specificity of DAPI to DNA has been probed by analysing its interactions with DNA octamers consisting of different base sequences, which include adenine, guanine, 2-amino adenine and inosine, using molecular mechanics methods. Presence of AT and non-AT base pairs in the immediate vicinity of the binding site, containing AT and non-AT base pairs is also investigated. Results show that DAPI most prefers to bind to homopolymer of AT, and least to the duplex containing alternating GC bases. DAPI interacts with homopolymeric duplexes in two possible orientations related by 180 degrees with nearly same affinity. Affinity of DAPI towards DNA comprising the modified bases, inosine and 2-amino adenine, is in between these extremities. The binding affinity is reduced to some extent by the occurrence of non AT bases flanking the four base paired binding region. An interesting revelation is that one can visualise DAPI to form a hydrogen bond with O2 of cytosine indicating that the 2-amino group of purines does not per se sterically preclude DAPI from residing in the minor groove of B-DNA helix. On the other hand, repulsive nature of electrostatic interactions that prevail at the minor groove consequent to the presence of these sequences contribute decisively in preventing further diffusion of the drug. Thus, electrostatics, rather than hydrogen bonding to bases, seemingly play an important role in determining the specificity of interaction. The retention of drug binders in the minor groove and therefore recognition, is governed by the combined effect of these various forces.

Base Sequence↗
PubMed1990

Visualisation of the gastrin receptor within rat mucosa using a biotinylated gastrin antagonist.

We have previously demonstrated that the peptide Boc-L-Trp-L-Leu-beta-Ala is a potent and specific antagonist of pentagastrin-stimulated acid secretion in both the rat and the dog. Using conventional solution phase methodology, the analogue biotinyl-L-Trp-L-Leu-beta-Ala was prepared in reasonable yield and purity and applied to cryostat sections of rat intestinal and other tissues. The sections were exposed to 5-10 micrograms of peptide and the bound analogue was visualised using streptavidin-fluorescein. The binding of the analogue was demonstrated in sections from fundus, duodenum, ileum, colon, and lung. However, the analogue failed to bind to tissue from the pancreas, heart, kidney, or liver. The binding of the probe was greatly reduced or completely inhibited by preincubation with Boc-L-Trp-L-Leu-beta-Ala, pentagastrin, or gastrin 1-17. The distribution of the cells recognised by the probe was consistent with the distribution of histamine-containing enterochromaffin-like cells. The results of this study may have some bearing on current theories of the mechanism of gastrin-stimulated acid release.

Amino Acid Sequence↗