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Biomedical subjects

D R Love

Publications and source records attributed to D R Love.

At least 19 recordsLinked to original sources
PubMed1999

Distribution of emerin and lamins in the heart and implications for Emery-Dreifuss muscular dystrophy.

Emerin is a nuclear membrane protein which is missing or defective in Emery-Dreifuss muscular dystrophy (EDMD). It is one member of a family of lamina-associated proteins which includes LAP1, LAP2 and lamin B receptor (LBR). A panel of 16 monoclonal antibodies (mAbs) has been mapped to six specific sites throughout the emerin molecule using phage-displayed peptide libraries and has been used to localize emerin in human and rabbit heart. Several mAbs against different emerin epitopes did not recognize intercalated discs in the heart, though they recognized cardiomyocyte nuclei strongly, both at the rim and in intranuclear spots or channels. A polyclonal rabbit antiserum against emerin did recognize both nuclear membrane and intercalated discs but, after affinity purification against a pure-emerin band on a western blot, it stained only the nuclear membrane. These results would not be expected if immunostaining at intercalated discs were due to a product of the emerin gene and, therefore, cast some doubt upon the hypothesis that cardiac defects in EDMD are caused by absence of emerin from intercalated discs. Although emerin was abundant in the membranes of cardiomyocyte nuclei, it was absent from many non-myocyte cells in the heart. This distribution of emerin was similar to that of lamin A, a candidate gene for an autosomal form of EDMD. In contrast, lamin B1 was absent from cardiomyocyte nuclei, showing that lamin B1 is not essential for localization of emerin to the nuclear lamina. Lamin B1 is also almost completely absent from skeletal muscle nuclei. In EDMD, the additional absence of lamin B1 from heart and skeletal muscle nuclei which already lack emerin may offer an alternative explanation of why these tissues are particularly affected.

Amino Acid Sequence↗
PubMed1998

Trinucleotide (CAG) repeat length is positively correlated with the degree of DNA fragmentation in Huntington's disease striatum.

Recent studies using DNA fragmentation assays suggest a role for apoptosis in cell death in Huntington's disease. In this study, we investigated the relationship between the degree of DNA fragmentation and the number of trinucleotide (CAG) repeats of the Huntington's disease gene in striatal tissue from Huntington's disease brains. We used frozen striatal tissue from 27 post mortem Huntington's disease brains (graded 0-4 on the Vonsattel classification, post mortem delay ranging from 4 to 41 h), plus control sections which were age, sex and post mortem delay matched from neurologically normal and Alzheimer's diseased striatal tissue. Our results show a significant positive correlation between the number of CAG repeats in the Huntington's disease gene and the degree of DNA fragmentation in Huntington's disease striatum. These results suggest that expanded CAG repeats in the Huntington's disease gene may lead to neuronal degeneration in Huntington's disease through an apoptotic mechanism.

Adult↗
PubMed1998

Influence of premedication with diazepam or morphine on the induction dose of eltanolone.

BACKGROUND: This study examined the influence of premedication with morphine or diazepam on the dose of eltanolone, a steroidal intravenous anaesthetic agent, required to induce anaesthesia. METHODS: Two hundred and sixteen patients, aged 18 to 65 years, were randomly assigned to receive premedication with diazepam 10 mg orally, morphine 10 mg intramuscularly, or placebo. The double-dummy technique was used to maintain blinding. Eltanolone 0.16-0.75 mg x kg(-1) was given intravenously over 20 s. At the commencement of injection patients were instructed to begin counting; if the patient ceased counting within 120 s and failed to respond to commands to continue, anaesthesia was considered to have been induced. The dose required to anaesthetise 50% of patients (ED50) was determined by logistic regression. RESULTS: The ED50 (95% confidence interval) of eltanolone in patients who received placebo premedication was 0.31 (0.27-0.34) mg x kg(-1). It was reduced slightly and nonsignificantly by premedication with diazepam, to 0.27 (0.24-0.30) mg x kg(-1), or morphine, to 0.26 (0.23-0.29) mg x kg(-1). Involuntary movement occurred in 65% of placebo premedicated patients. Its incidence was not significantly reduced by diazepam (57%), but was significantly (P<0.001) reduced by morphine (37%). Morphine premedication was, however, associated with a significant (P<0.01) increase in the incidence of apnoea (21%) compared to placebo premedicated patients (4%). CONCLUSION: Premedication with diazepam or morphine had little influence on the dose of eltanolone required to induce anaesthesia.

Adjuvants, Anesthesia↗
PubMed1997

Mutations in the adrenoleukodystrophy gene.

Adrenoleukodystrophy (ALD) is a peroxisomal disorder that commonly manifests as demyelination of the central nervous system (CNS). The isolation of the ALD gene by positional cloning has led to the identification of a variety of mutations in the ALD gene. One hundred and ten mutations have been identified to date, of which approximately 50% are missense mutations. While rapid DNA-based diagnoses of ALD is now possible, there appears to be no simple correlation between genotype and phenotype.

ATP Binding Cassette Transporter, Subfamily D, Mem↗
PubMed1996

DNA-based diagnostics for adrenoleukodystrophy in a large New Zealand family.

AIM: To develop a DNA-based diagnostic test for adrenoleukodystrophy (ALD) in a large New Zealand family. METHODS: Mutation screening of the X chromosome-linked ALD gene was undertaken by direct sequencing of PCR amplified products encompassing defined exons of the ALD gene. The identification of a mutation led to the development of a simple restriction enzyme digestion protocol of a PCR amplified product to identify those individuals with the mutation. RESULTS: A nonsense mutation, resulting in deduced premature termination of translation of the ALD gene product, was detected in exon 4 of the ALD gene in an affected male. This mutation was found in three obligate gene carriers in the same ALD family. A DNA-based test was established to identify this mutation by Bgl II digestion of a PCR amplified product encompassing exons 3 and 4 of the ALD gene. The DNA-based test was applied to a chorionic villus sampling for prenatal diagnosis. CONCLUSIONS: A simple DNA-based test has been developed for ALD in a large New Zealand family. This test provides a rapid means of determining carrier status and for undertaking prenatal diagnosis for ALD in this family.

Adolescent↗
PubMed1996

Structure and location of the murine adrenoleukodystrophy gene.

X-linked adrenoleukodystrophy (ALD) is a degenerative neurological disease characterized by the accumulation of very long chain fatty acids in various tissues and demyelination of the central nervous system. The human gene responsible for the disease encodes a membrane-bound ATP-binding transporter protein that is located in peroxisomes. We isolated the mouse adrenoleukodystrophy gene, determined its structure, and mapped it both cytogenetically and genetically. The mouse gene is very similar in structure to the human gene, consisting of 10 exons arranged over a 22-kb genomic region. We localized it in band B of the mouse X chromosome by fluorescence in situ hybridization analysis and, using a new microsatellite repeat polymorphism, determined the map location as 47 cM from the X centromere. We found evidence for other sequences in the mouse genome related to the 3' end of Aldgh. This study paves the way for the construction of gene-targeting plasmids that may be used to develop an animal model of ALD.

ATP Binding Cassette Transporter, Subfamily D, Mem↗
PubMed1996

Molecular analysis of the Huntington's disease gene in New Zealand.

AIMS: To establish and validate a polymerase chain reaction (PCR)-based diagnostic test in New Zealand, which enables the number of CAG repeats present in the Huntington's disease (HD) gene to be determined with speed and accuracy. To develop procedures for reporting and counselling probands and families. METHODS: The analysis of the CAG repeat region in Huntington's disease and normal chromosomes involved PCR amplification of genomic DNA using either the incorporation of radioactive deoxynucleotides or fluorescent oligonucleotide primers. RESULTS: The molecular analysis of the CAG repeat sequence in the Huntington's disease gene of over 100 New Zealand individuals has been performed. Huntington's disease chromosomes contained 37-70 (median 44) repeats whereas normal chromosomes contained 9-27 (median 18) repeats. Six individuals from three families had an allele in the intermediate range (30-36 repeats). Instability of the CAG repeat upon transmission from generation to generation was also observed. A comparison of the results obtained using radioactive and fluorescent assays indicates that while both methods are reliable, the latter method is more rapid and allows for automation to be incorporated in the scoring of allele sizes. CONCLUSIONS: Our analysis of Huntington's disease alleles has shown a profile of CAG repeat lengths that is consistent with those reported internationally. In addition, reporting and counselling procedures have been established for presymptomatic testing of Huntington's disease in New Zealand.

DNA↗
PubMed1996

Reduction in enkephalin and substance P messenger RNA in the striatum of early grade Huntington's disease: a detailed cellular in situ hybridization study.

The expression of enkephalin and substance P messenger RNAs was examined in the caudate-putamen of human post mortem tissue from control and Huntington's disease tissue using in situ hybridization techniques and human specific enkephalin and substance P [35S] oligonucleotides. Macroscopic and microscopic quantification of enkephalin and substance P gene expression was carried out using computer-assisted image analysis. Tissue was collected from six control cases with no sign of neurological disease and six Huntington's disease cases ranging from grades 0 to 3 as determined by neuropathological evaluation. The clinical and pathological diagnosis of Huntington's disease was confirmed unequivocally by genetic analysis of the CAG repeat length in both copies of IT15, the Huntington's disease gene. A marked reduction in both enkephalin and substance P messenger RNAs was detected in all regions of the caudate nucleus and putamen in Huntington's disease grades 2/3 when compared to controls; in the dorsal caudate few enkephalin or substance P messenger RNA-positive cells were detected. For the early grade (0/1) Huntington's disease cases, a heterogeneous reduction in both enkephalin and substance P messenger RNAs were noted; for enkephalin messenger RNA the striatal autoradiograms displayed a conspicuous patchy appearance. Detailed cellular analysis of the dorsal caudate revealed a striking reduction in the number of enkephalin and substance P messenger RNA-positive cells detected and in the intensity of hybridization signal/cell. These data suggest that both the "indirect" GABA/enkephalin and "direct" GABA/substance P pathways are perturbed very early in the course of the disease and that these early changes in chemical signalling may possibly underlie the onset of clinical symptoms.

Aged↗
PubMed1996

Decreased neuronal nitric oxide synthase messenger RNA and somatostatin messenger RNA in the striatum of Huntington's disease.

The cellular abundance of neuronal nitric oxide synthase and somatostatin messenger RNAs was compared in the caudate nucleus, putamen and sensorimotor cortex of Huntington's disease and control cases. Neuronal nitric oxide synthase messenger RNA was significantly decreased in the caudate nucleus and putamen, but not in the sensorimotor cortex in Huntington's disease; the decrease in neuronal nitric oxide synthase messenger RNA became more pronounced with the severity of the disease. Somatostatin gene expression was significantly decreased in the dorsal putamen in Huntington's disease, but was essentially unchanged in all other regions examined. The density of neurons expressing detectable levels of neuronal nitric oxide synthase messenger RNA was reduced in the striata of Huntington's disease cases with advanced pathology; the density of neurons expressing detectable levels of somatostatin messenger RNA was similar in control and Huntington's disease cases. Neuropeptide Y-, somatostatin- and NADPH-diaphorase-positive neurons were consistently present throughout the striatum across all the grades of the disease. Neuronal nitric oxide synthase and NADPH-diaphorase activity (a histochemical marker for nitric oxide synthase-containing neurons) co-localize with somatostatin and neuropeptide Y in interneurons in the human striatum and cerebral cortex. Although the neurodegeneration associated with Huntington's disease is most evident in the striatum (particularly the dorsal regions), neuronal nitric oxide synthase/neuropeptide Y/somatostatin interneurons are relatively spared. Nitric oxide released by neuronal nitric oxide synthase-containing neurons may mediate glutamate-induced excitotoxic cell death, a mechanism proposed to be instrumental in causing the neurodegeneration seen in Huntington's disease. The results described here suggest that although the population of interneurons containing somatostatin, neuropeptide Y and neuronal nitric oxide synthase do survive in the striatum in Huntington's disease they are damaged during the course of the disease. The results also show that the reduction in neuronal nitric oxide synthase and somatostatin messenger RNAs is most pronounced in the more severely affected dorsal regions of the striatum. Furthermore, the loss of neuronal nitric oxide messenger RNA becomes more pronounced with the severity of the disease; thus implying a down-regulation in neuronal nitric oxide synthase messenger RNA synthesis, and potentially neuronal nitric oxide synthase protein levels, in Huntington's disease.

Aged↗
PubMed1996

A comparison of variable-dose patient-controlled analgesia with fixed-dose patient-controlled analgesia.

We examined the effect on the quality of analgesia and side effects of increasing the patient control component of morphine patient-controlled analgesia (PCA) by offering the patient a choice of bolus dose sizes. Using a three-button hand piece, patients could choose between 0.5-, 1.0-, and 1.5-mg boluses of morphine (variable-dose PCA, VDPCA). Successful demands were delivered by a modified Graseby 3400 Anaesthesia Pump controlled by a Toshiba T1900 computer. This system was compared with conventional fixed-dose PCA (FDPCA) (1.0 mg of morphine) delivered by a Graseby 3300 PCA Pump. Both treatment groups had a 5-min lockout interval. Sixty patients were randomly assigned to receive either VDPCA or FDPCA after major abdominal gynecological surgery or hip or knee arthroplasty. Treatment groups did not differ in their duration of PCA therapy, total morphine consumption, or time spent with mild or severe oxyhemoglobin desaturation. There were no differences in their ease of controlling pain, satisfaction with pain control, experience of pain on movement, quality of sleep, severity of nausea, or incidence of vomiting. Although the more complex VDPCA technique provides adequate postoperative analgesia, it does not offer any advantage over conventional FDPCA.

Adult↗
PubMed1996

Main clinical features of the three mapped autosomal recessive limb-girdle muscular dystrophies and estimated proportion of each form in 13 Brazilian families.

Autosomal recessive limb-girdle muscular dystrophies (AR LGMD) represent a group of muscle diseases with a wide spectrum of clinical signs, varying from very severe to mild. Four different loci that when mutated cause the AR LGMD phenotype have been mapped or cloned or both: in two of them the linked families seem to have a relatively mild phenotype (LGMD2a and LGMD2b), in the third one the reported linked families show a more severe clinical course (LGMD2c), while mutations in the fourth locus may cause severe or mild phenotypes (LGMD2d). The relative proportion of each of these genetic forms among the LGMD families and whether there are other genes that when mutated cause this phenotype is unknown. The closest available informative markers for each of the mapped AR LGMD genes have been tested in 13 Brazilian families with at least three affected patients. The findings from the present report confirm non-allelic heterogeneity for LGMD and suggest that in our population about 33% of the LGMD families are caused by mutations in the 15q gene, 33% in the 2p gene, 17% by mutations in the adhalin gene, and less than 10% may be by mutations at the 13q locus. They also suggest that there is at least one other gene responsible for this phenotype. In addition, the main clinical features of the different forms are discussed.

Adolescent↗
PubMed1995

Molecular characterization of further dystrophin gene microsatellites.

Microsatellites of the dystrophin gene have been used extensively in the genetic analysis of Duchenne and Becker muscular dystrophy families. The microsatellites that have been reported to date are clustered within disparate regions of the dystrophin gene, specifically at the 5'-end and in the central rod-domain. YACs encompassing the gene were screened for further microsatellites to improve the density of available genetic markers. Four microsatellites were localized to defined regions of the dystrophin gene by the analysis of patient DNA samples, somatic cell hybrids and YACs. In addition, varying combinations of microsatellite loci were amplified in multiplex PCRs, which complement those loci that have been studied to date.

Base Sequence↗
PubMed1995

A mutation in the alpha tropomyosin gene TPM3 associated with autosomal dominant nemaline myopathy.

Nemaline myopathies are diseases characterized by the presence in muscle fibres of pathognomonic rod bodies. These are composed largely of alpha-actinin and actin. We have identified a missense mutation in the alpha-tropomyosin gene, TPM3, which segregates completely with the disease in a family whose autosomal dominant nemaline myopathy we had previously localized to chromosome 1p13-q25. The mutation substitutes an arginine residue for a highly conserved methionine in a putative actin-binding site near the N terminus of the alpha-tropomyosin. The mutation may strengthen tropomyosin - actin binding, leading to rod body formation, by adding a further basic residue to the postulated actin-binding motif.

Amino Acid Sequence↗
PubMed1994

A multiple interval physical map of the pericentromeric region of human chromosome 10.

Five intervals in the pericentromeric region of human chromosome 10 have been defined using a panel of somatic cell hybrids carrying portions of the chromosome. The map positions of twelve markers, consisting of four genes and eight anonymous DNA segments, have been localized by assignment to one of the five intervals. Several other markers could be placed in specific intervals by genetic linkage to assigned loci. When previously published data are incorporated, the summary map of the pericentromeric region encompasses thirty-two loci in bands 10p11.2-q11.2.

Base Sequence↗
PubMed1993

Germ-line mutations of the RET proto-oncogene in multiple endocrine neoplasia type 2A.

Multiple endocrine neoplasia type 2A (MEN 2A) is a dominantly inherited cancer syndrome that affects tissues derived from neural ectoderm. It is characterized by medullary thyroid carcinoma (MTC) and phaeochromocytoma. The MEN2A gene has recently been localized by a combination of genetic and physical mapping techniques to a 480-kilobase region in chromosome 10q11.2 (refs 2,3). The DNA segment encompasses the RET proto-oncogene, a receptor tyrosine kinase gene expressed in MTC and phaeochromocytoma and at lower levels in normal human thyroid. This suggested RET as a candidate for the MEN2A gene. We have identified missense mutations of the RET proto-oncogene in 20 of 23 apparently distinct MEN 2A families, but not in 23 normal controls. Further, 19 of these 20 mutations affect the same conserved cysteine residue at the boundary of the RET extracellular and transmembrane domains.

Amino Acid Sequence↗
PubMed1993

Dystrophin and dystrophin-related proteins: a review of protein and RNA studies.

The analysis of dystrophin gene expression has led to the identification of multiple transcripts and varying isoforms. The data indicate that transcription of the dystrophin gene occurs from several promoters, which involves developmental and tissue-dependent regulation. These discoveries have complicated the interpretation of immunolocalization studies, although there is a strong correlation between the amount and size of dystrophin and the severity of the clinical phenotype. The importance of using protein-specific antibodies for dystrophin analysis has been underscored by the identification of a protein, designated utrophin, which exhibits significant sequence homology with dystrophin. This review addresses the recent studies of dystrophin and utrophin expression in an attempt to illustrate the transcriptional diversity of these large genes and the localization of their protein products within various tissues.

Amino Acid Sequence↗