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Biomedical subjects

G R Sutherland

Publications and source records attributed to G R Sutherland.

At least 109 records · Page 6Linked to original sources
PubMed1999

GPR56, a novel secretin-like human G-protein-coupled receptor gene.

A novel gene product, GPR56, with homology to the seven transmembrane-domain receptor superfamily, has been cloned by PCR amplification using degenerate oligonucleotide primers and subsequent screening of a human heart cDNA library. The isolated 2.8-kb cDNA clone encodes a protein of 693 amino acids that shows highest identity (32%) to HE6, a member of a subclass of the class B secretin-like G-protein-coupled receptors. Northern analysis of various human tissues revealed a wide distribution of the transcript with highest levels found in thyroid gland, brain, and heart. In situ hybridization analysis of human thyroid gland as well as rat heart and brain tissue confirms these results and identifies the hippocampus and hypothalamic nuclei as brain areas with particularly high expression of GPR56 mRNA. The high level of mRNA expression, its wide distribution, and the mucin-like extracellular domain of the receptor protein suggest a possible role for this receptor in cell-cell interaction processes. The human gene for GPR56 has been isolated and its exon-intron structure determined. The total length of the human GPR56 gene is approximately 15 kb, and it consists of 13 exons. Fluorescence in situ hybridization, PCR analysis of somatic cell hybrids, and interspecific mouse backcross mapping have localized the genes to human chromosome 16q13 and mouse chromosome 8.

Amino Acid Sequence↗
PubMed1999

Fibroblast growth factor homologous factor 2 (FHF2): gene structure, expression and mapping to the Börjeson-Forssman-Lehmann syndrome region in Xq26 delineated by a duplication breakpoint in a BFLS-like patient.

Börjeson-Forssman-Lehmann syndrome (BFLS) is a syndromal X-linked mental retardation, which maps by linkage to the q26 region of the human X chromosome. We have identified a male patient with BFLS-like features and a duplication, 46,Y,dup(X)(q26q28), inherited from his phenotypically normal mother. Fluorescence in situ hybridisation using yeast artificial chromosome clones from Xq26 localised the duplication breakpoint to an approximately 400-kb interval in the Xq26.3 region between DXS155 and DXS294/DXS730. Database searches and analysis of available genomic DNA sequence from the region revealed the presence of the fibroblast growth factor homologous factor gene, FHF2, within the duplication breakpoint interval. The gene structure of FHF2 was determined and two new exons were identified, including a new 5' end exon, 1B. FHF2 is a large gene extending over approximately 200 kb in Xq26.3 and is composed of at least seven exons. It shows tissue-specific alternative splicing and alternative transcription starts. Northern blot hybridisation showed highest expression in brain and skeletal muscle. The FHF2 gene localisation and tissue-specific expression pattern suggest it to be a candidate gene for familial cases of the BFLS syndrome and other syndromal and non-specific forms of X-linked mental retardation mapping to the region.

Alternative Splicing↗
PubMed1999

Detection of a novel missense mutation and second recurrent mutation in the CACNA1A gene in individuals with EA-2 and FHM.

Mutations in the brain specific P/Q type Ca2+ channel alpha1 subunit gene, CACNA1A, have been identified in three clinically distinct disorders, viz. episodic ataxia type 2 (EA-2), familial hemiplegic migraine (FHM) and spinocerebellar ataxia 6 (SCA6). For individuals with EA-2, the mutations described thus far are presumed to result in a truncated protein product. Several different missense mutations have been identified in patients with FHM. At least two of these mutations have been identified on two different chromosome 19p13 haplotypes and thus represent recurrent mutations. In the present study, we have screened several individuals for mutations in all 47 exons in the CACNA1A gene by single-strand conformation analysis. We have characterised a novel missense mutation, G5260A, in exon 32 in a family segregating for EA-2. The consequence of this mutation is an amino acid substitution at a highly conserved position within the CACNA1A gene. This represents the first point mutation not resulting in a proposed truncated protein. Furthermore, this mutation has been detected in a family member with mild clinical signs including only migraine. Additionally, a second previously identified recurrent muta tion, C2272T, in exon 16 has been discovered in a patient with FHM.

Amino Acid Sequence↗
PubMed1999

C16orf5, a novel proline-rich gene at 16p13.3, is highly expressed in the brain.

A novel gene has been characterized, designated C16orf5, with an unusually high content of proline residues (40% over 104 residues) at the N-terminus of the protein. The C-terminus of the protein is also cysteine rich with 14 cysteine residues present. Analysis using Northern and dot blots showed that the highest expression of this gene is in the brain. The gene was located on chromosome 16 at band p13.3 by FISH to metaphase chromosomes. Southern blot analysis with a human-rodent somatic cell hybrid panel showed a location between the somatic hybrid breakpoints 23HA and CY196. This gene comprises at least four exons and an open reading frame of 786 bp encoding a predicted protein of 261 amino acids. Analysis of this protein using PSORTII predicted a nuclear localization.

Amino Acid Sequence↗
PubMed1999

How accurate is visual assessment of synchronicity in myocardial motion? An In vitro study with computer-simulated regional delay in myocardial motion: clinical implications for rest and stress echocardiography studies.

Asynchronicity in echocardiographic images is normally assessed visually. No prior quantitative studies have determined the limitations of this approach. To quantify visual recognition of myocardial asynchronicity in echocardiographic images, computer-simulated delay phantom loops were generated from a 3.3 MHz digital image data from a normal left ventricular short-axis heart cycle acquired at 55 frames per second. Six expert observers visually assessed 30 abnormal and 3 normal loops with differing computer-induced delay patterns on 3 occasions and in this optimally simulated environment could recognize only single delays of 89 ms or more. This was improved to 71 ms or more by use of side-by-side (normal versus abnormal) comparative review. Thus visual assessment of clinically important regional delay in rest or stress echo images is limited.

Computer Simulation↗
PubMed1999

Anatomic M-mode echocardiography: A new approach to assess regional myocardial function--A comparative in vivo and in vitro study of both fundamental and second harmonic imaging modes.

OBJECTIVE: To evaluate the accuracy of anatomic M-mode echocardiography (AMM). METHODS: Eight phantoms were rotated on a device at different insonation depths (IDs) in a water beaker. They were insonated with different transducer frequencies in fundamental imaging (FI) and second harmonic imaging (SHI), and the diameters were assessed with conventional M-mode echocardiography (CMM) and AMM with the applied angle correction (AC) after rotation. In addition, left ventricular wall dimensions were measured with CMM and AMM in FI and SHI in 10 volunteers. RESULTS: AC had the greatest effect on the measurement error in AMM followed by ID (AC: R2 = 0. 295, ID: R2 = 0.268; P <.0001). SHI improved the accuracy, and a difference no longer existed between CMM and AMM with an AC up to 60 degrees. In vivo the limit of agreement between AMM and CMM was -1.7 to +1.8 mm in SHI. CONCLUSION: Within its limitations (AC < 60 degrees; ID < 20 cm), AMM could be a robust tool in clinical practice.

Echocardiography↗
PubMed1999

Molecular cloning of a novel human PAPS synthetase which is differentially expressed in metastatic and non-metastatic colon carcinoma cells.

Subtractive hybridisation was used to select for genes which are differentially expressed between a highly metastatic human colon carcinoma cell line, KM12SM, and the isogenetic non-metastatic cell line, KM12C. This led to the isolation of cDNA clones for a novel human adenosine 5'-phosphosulphate kinase/ATP sulphurylase (PAPS synthetase). Northern hybridisation revealed a single 4.2 kb mRNA species which showed an approximately 20-fold higher level of expression in the non-metastatic cell line than in the metastatic cell line. The overlapping cDNA clones together covered 3,774 bp including the entire coding region of 1,842 bp encoding a protein of 614 amino acids (calculated molecular mass of 69,496 Da). The protein contains consensus sequences for APS kinase and ATP sulphurylase, in its amino- and carboxy-terminal regions, respectively, as well as other sequences that are highly conserved amongst ATP sulphurylases and APS kinases. Interestingly, consensus sequences for GTPase activity were also identified, indicating that enzyme activity may be regulated by an intrinsic GTPase mechanism. Overall the new protein is 78% homologous with a previously described human PAPS synthetase (PAPSS1) indicating that we have identified the second member of a gene family which we have provisionally named PAPSS2. The gene locus for PAPSS2 was identified on chromosome 10 at 10q23.1-q23.2. This locus has synteny with the mouse brachymorphic gene recently identified as a PAPS synthetase (SK2). PAPSS2 appears to be the human homologue of this gene and thus PAPSS2 is likely to be important in human skeletogenesis.

Amino Acid Sequence↗
PubMed1999

Molecular cloning and characterization of a cDNA encoding the human leucocyte vacuolar protein sorting (h1Vps45).

We have isolated a novel cDNA clone from human leucocyte cDNA library, encoding a Sec1p-like vacuolar protein sorting (h1Vps45) which is believed to be implicated in vesicular transportation. Although the deduced amino acid (AA) sequence of this cDNA has revealed 97% identity to other known mammalian vacuolar protein sorting, there is an extensive variation in nucleotide sequence in comparison to that of three previously reported human (hVps45), rat (rVps45) and mouse (mVps45) vacuolar protein sorting (Vps45) cDNAs [1-3]. At the nucleotide sequence level h1Vps45 demonstrated 90% homology to the hVps45 and rVps45 and 89% identity to mVps45 with no significant homology in their noncoding regions. The 2.4 Kb mRNA corresponding to the h1Vps45 clone is widely distributed in a variety of human tissues expressing highest levels in peripheral blood mononuclear cells (PBMC), neutrophils, heart, spleen, and testis. The chromosomal mapping studies have demonstrated that the h1Vps45 is localized to long arm of human chromosome 1 at q21-q22. Our data indicates that we have isolated, characterized and mapped a novel cDNA encoding h1Vps45, which may play an important role in protein trafficking as well as have clinical significance in the release of inflammatory mediators e.g. histamine, bradykinin and cytokine release.

Amino Acid Sequence↗
PubMed1999

Utility of a moveable 1.5 Tesla intraoperative MR imaging system.

OBJECTIVE: This study demonstrates the utility of a newly-developed moveable 1.5 Tesla intraoperative MR imaging system using a case report of a multi-lobulated parafalx meningioma. CLINICAL PRESENTATION: A 43-year-old female presented with progression of a multi-lobulated anterior parafalx meningioma several years following resection of a large left frontal convexity meningioma. INTERVENTION AND TECHNIQUE: Surgical excision of the lesion was undertaken. Following apparent total resection, intraoperative MR imaging revealed two residual dumbell shaped lobules. Using these updated MR images, the tumour was readily identified and removed. CONCLUSION: The moveable 1.5 Tesla intraoperative MR system used in the present case provides rapid, high resolution MR images during neurosurgical procedures. Moving the magnet out of the surgical field during surgery permits the use of all standard neurosurgical instruments. The ease of use and quality of images combined with minimal interference on well-established surgical techniques makes this system a valuable adjunct in the neurosurgical treatment of intracranial disease.

Adult↗
PubMed1999

Homozygotes for FRA16B are normal.

Homozygotes for the rare folate-sensitive autosomal fragile sites have never been recorded. Two non-folate-sensitive rare fragile sites (FRA10B and FRA17A) have been previously recorded in normal individuals. We document two unrelated normal individuals who are homozygotes for the rare fragile site FRA16B and record the patterns of induction of this fragile site with berenil. The existence of normal homozygotes for FRA16B suggests that this fragile site is not within a gene essential for normal development.

Adult↗
PubMed1999

The Batten disease gene product (CLN3p) is a Golgi integral membrane protein.

Batten disease (juvenile neuronal ceroid lipofuscinosis) is a recessive neurodegenerative disorder of childhood. The gene, CLN3, was recently identified and found to encode a novel 438 amino acid protein of unknown function. In order to gain insight into the function of the Batten disease protein (CLN3p), we investigated its subcellular localization. Protein constructs incorporating CLN3p fused to the green fluorescence protein or an eight amino acid peptide tag were transiently expressed in fibroblasts, HeLa and COS-7 cells. A juxtanuclear, asymmetric localization pattern was observed that correlated with the Golgi apparatus in all three cell types. However, a proportion of transiently transfected cells exhibited a punctate vesicular distribution throughout the cytoplasm in addition to or without the Golgi localization. In order to account for localization patterns arising from intracellular protein transport disruption due to exaggerated overexpression in transiently transfected cells, we isolated a stably transfected cell line expressing only one copy of the CLN3 -GFP DNA construct. Fluorescence and biochemical analyses using this cell line demonstrated that CLN3p is an integral membrane protein that localizes primarily in the Golgi apparatus. The functional implications of this finding are discussed.

Animals↗
PubMed1999

Serial magnetic resonance imaging of rat brain after induction of renal hypertension.

BACKGROUND AND PURPOSE: Hypertension is a major risk factor for ischemic and hemorrhagic stroke and may also cause more chronic and subtle brain injury. Progressive brain changes in a rat model of renal hypertension have been assessed to better understand the pathogenesis of hypertensive brain damage. METHODS: Young adult rats were made hypertensive by partial occlusion of both renal arteries. MR images of brain were obtained weekly, and histopathological outcome was assessed. A separate group of rats was used to measure brain specific gravity and Evans blue dye content as an indicator of extravasation. RESULTS: Rats developed maximal mean systolic blood pressures of 173 to >300 mm Hg, reaching a plateau in 6 to 8 weeks. Rats whose mean systolic pressure never exceeded 210 mm Hg never had brain lesions, while rats whose mean systolic pressure exceeded 276 mm Hg consistently developed brain lesions. Brain T2 values increased with increasing blood pressure. Lesions seen on MRI corresponded to those seen histologically. MRI also demonstrated transient brain expansion, probably due to diffusely increased water content, and rarely demonstrated focal cortical edema, which had no histological correlate. These transient phenomena, as well as hemorrhagic and ischemic infarcts, occurred mainly during the phase of climbing blood pressure and early stages of stable hypertension. CONCLUSIONS: Serial MRI reveals aspects of hypertensive brain disease that cannot be studied by histological examination alone. The observed phenomena are likely related to loss of autoregulation and/or blood-brain barrier integrity. Breach of blood vessel integrity is less likely once the vessels become accustomed to high pressures.

Animals↗
PubMed1999

Partial seizures with focal epileptogenic electroencephalographic patterns in three related female patients with fragile-X syndrome.

Epilepsy and abnormal electroencephalographic (EEG) patterns have been reported in mentally retarded males with fragile-X syndrome, but the high incidence of epilepsy in such persons has been recognized only recently. These individuals have focal spikes in the EEG similar to the benign rolandic pattern. Female carriers have very rarely been reported to have epilepsy or nonspecific abnormal EEG patterns. We report partial seizures with a focal epileptogenic EEG pattern in two sisters and their grandmother, who are all carriers of fragile-X syndrome. The sisters have mild developmental delay, but the grandmother is of normal intelligence. The mother of the two sisters is known to be a carrier of the fragile-X chromosome and is of normal intelligence, with no history of seizures. It is important for physicians to be aware of the possibility that females presenting with partial seizures of unknown cause may be fragile-X carriers, and enquiry for a family history of intellectual disability should be pursued.

Adult↗
PubMed1999

Hypothermia: depression of tricarboxylic acid cycle flux and evidence for pentose phosphate shunt upregulation.

OBJECT: Hypothermia is used in neurosurgery and other surgical disciplines to reduce tissue injury, but the mechanism of such protection remains elusive. The authors have endeavored to delineate the mechanism of neural protection afforded by hypothermia through a study of glucose metabolism. METHODS: Nuclear magnetic resonance spectroscopy was used to follow the carbon-13 label from [1-13C]glucose as it was metabolized through the glycolytic and tricarboxylic acid pathways. Male Sprague-Dawley rats were maintained at either 37.5 degrees C or 31 degrees C and infused with labeled glucose for 10, 30, 60, 100, or 200 minutes (five rats were used for each time point and for each temperature). At the end of the infusion period, the rats' brains were subjected to rapid freeze-funnel fixation. Water-soluble metabolites were extracted from samples of the neocortex and hippocampus by using perchloric acid extraction. The fractional enrichment of these metabolites was used to calculate the reaction rate constant of formation and steady-state enrichment for a number of metabolites. Hypothermia resulted in a 30 to 40% depression of metabolism (p < 0.0001) in both the neocortex and hippocampus. Steady-state fractional enrichment of metabolites was also decreased by 20 to 25% with hypothermia (p < 0.0001), implying a loss of label during metabolism. CONCLUSIONS: The results of this study suggest that an increased fraction of glucose metabolism was shunted through the pentose phosphate pathway in the presence of hypothermia.

Animals↗
PubMed1999

A mobile high-field magnetic resonance system for neurosurgery.

OBJECT: The authors' goal was to place a mobile, 1.5-tesla magnetic resonance (MR) imaging system into a neurosurgical operating room without adversely affecting established neurosurgical management. The system would help to plan accurate surgical corridors, confirm the accomplishment of operative objectives, and detect acute complications such as hemorrhage or ischemia. METHODS: The authors used an actively shielded 1.5-tesla magnet, together with 15 mtesla/m gradients, MR console computers, gradient amplifiers, a titanium, hydraulic-controlled operating table, and a radiofrequency coil that can be disassembled. The magnet is moved to and from the surgical field by using overhead crane technology. To date, the system has provided unfettered access in 46 neurosurgical patients. In all patients, high-definition T1- and/or T2-weighted images were rapidly and reproducibly acquired at various stages of the surgical procedures. Eleven patients underwent craniotomy that was optimized after preincision imaging. In four patients who harbored subtotally resected tumor, intraoperative MR imaging aided the surgeon in removing the remaining tumor. Interestingly, the intraoperative administration of gadolinium demonstrated a dynamic expansion of enhancement beyond the preoperative contrast contour in patients with malignant glioma. These zones of new enhancement proved, on examination of biopsy samples, to be tumor. CONCLUSIONS: The authors have demonstrated that high-quality MR images can be obtained in the operating room within reasonable time constraints. Procedures can be conducted without compromising or altering traditional neurosurgical, nursing, or anesthetic techniques. It is feasible that within the next decade intraoperative MR imaging may become the standard of care in neurosurgery.

Adult↗