PubMed Health⌕ Search

Biomedical subjects

G A Harrison

Publications and source records attributed to G A Harrison.

At least 19 recordsLinked to original sources
PubMed2005

Analysis of the genomic region containing the tammar wallaby (Macropus eugenii) orthologues of MHC class III genes.

Major histocompatibility complex (MHC) molecules are central to development and regulation of the immune system in all jawed vertebrates. MHC class III cytokine genes from the tumor necrosis factor core family, including tumor necrosis factor (TNF) and lymphotoxin alpha and beta (LTA, LTB), are well studied in human and mouse. Orthologues have been identified in several other eutherian species and the cDNA sequences have been reported for a model marsupial, the tammar wallaby. Comparative genomics can help to determine gene function, to understand the evolution of a gene or gene family, and to identify potential regulatory regions. We therefore cloned the genomic region containing the tammar LTB, TNF, and LTA orthologues by "genome walking", using primers designed from known tammar sequences and regions conserved in other species. We isolated two tammar BAC clones containing all three genes. These tammar genes show similar intergenic distances and the same transcriptional orientation as in human and mouse. Gene structures and sequences are also very conserved. By comparing the tammar, human and mouse genomic sequences we were able to identify candidate regulatory regions for these genes in mammals. Full length sequencing of BACs containing the three genes has been partially completed, and reveals the presence of a number of other tammar MHC III orthologues in this region.

Animals↗
PubMed2002

cDNA cloning of the polymeric immunoglobulin receptor of the marsupial Macropus eugenii (tammar wallaby).

cDNA encoding a marsupial polymeric immunoglobulin receptor (pIgR) was isolated from Macropus eugenii (tammar wallaby) mammary lymph node primarily by reverse transcriptase coupled polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) PCR. This resulted in a 5' truncated clone and, in order to obtain the full-length sequence, genomic walking PCR was utilized. The complete sequence consists of 2696 bp of cDNA and encodes a predicted polypeptide of 732 amino acids. The wallaby sequence is highly conserved in relation to the only other reported marsupial pIgR sequence, that of Trichosurus vulpecula (brushtail possum), having a nucleotide identity of 86.7% and a deduced amino acid identity of 79.9%. The wallaby nucleotide sequence also has a moderate degree of similarity with the pIgR sequences of eutherian mammals, being most similar to that of the rat, with an identity of 63.1%. At the amino acid level, in comparison to eutherian sequences, the wallaby pIgR is most similar to that of humans with an identity of 52.6%. pIgR phylogenetic trees were constructed for tammar wallaby, brushtail possum and several eutherian mammal cDNA and deduced amino acid sequences. In both DNA and protein analyses, the eutherian sequences formed a sister clade to the exclusion of the marsupial sequences, in agreement with the current view of mammalian evolution.

Amino Acid Sequence↗
PubMed2002

Molecular cloning of four lambda light chain cDNAs from the Australian brushtail possum Trichosurus vulpecula.

A brushtail possum mesenteric lymph node cDNA library was screened with a grey short-tail opossum Clambda probe and four immunoglobulin lambda cDNAs were isolated. Two of the isolated clones (L5 and L10) contained identical framework 4 regions and constant regions (but different variable regions), suggesting that the possum lambda locus is organized as multiple J-C pairs--a feature seen in the opossum and placental mammals. The cloning of the lambda light chain cDNAs signifies the completion of the basic molecular characterization of the brushtail possum immunoglobulin repertoire. The availability of this sequence data will allow extensive analysis of the immune response of the brushtail possum at the molecular level, as well as the development of specific immunological reagents for detection of immunoglobulin molecules at the protein level.

Amino Acid Sequence↗
PubMed2002

Bilateral vocal cord palsy following interscalene brachial plexus nerve block.

Acute respiratory complications of an interscalene brachial plexus block include ipsilateral phrenic nerve and recurrent laryngeal nerve palsies. A 71-year-old woman who had undergone a total thyroidectomy for papillary carcinoma 35 years ago was administered a right interscalene brachial plexus block for a shoulder hemi-arthroplasty. Subsequently she developed acute respiratory distress associated with marked stridor secondary to an acute right vocal cord palsy, which was superimposed on what was assumed to be a preexisting left-sided vocal cord palsy. On extubation the patient was noted to develop stridor again necessitating reintubation and tracheostomy was performed two weeks later. The vocal cord palsies failed to resolve over the subsequent 18-month follow-up. We describe this case to highlight the significant risk of this procedure in patients with preexisting or suspected contralateral vocal cord palsy.

Aged↗
PubMed2001

Characterisation of the kappa light chain of the brushtail possum (Trichosurus vulpecula).

Two full length cDNA sequences encoding the kappa light chain of the Australian marsupial, Trichosurus vulpecula, the brushtail possum, were isolated from a mesenteric lymph node cDNA library. The constant regions (Ckappa) of the two light chains were identical, but the variable (Vkappa) and joining (Jkappa) regions were different. At the amino acid level, possum Ckappa was most similar to Ckappa of an American marsupial, Monodelphis domestica (75%), with similarity to eutherian Ckappa ranging from 47 to 63%. The availability of molecular data will enable the development of immunological reagents for studying immune responses and disease in marsupials, thereby aiding conservation strategies and veterinary medicine.

Amino Acid Sequence↗
PubMed2001

Cloning of the MHC class II DRB cDNA from the brushtail possum (Trichosurus vulpecula).

The cell-surface glycoproteins encoded by the major histocompatibility complex (MHC) bind to processed foreign antigens and present them to T lymphocytes. Two classes of MHC molecules and their corresponding gene sequences have been extensively studied in eutherian mammals and birds, but data on the marsupial MHC are limited. Marsupials split from eutherian mammals about 125 million years ago and represent a distinct branch in mammalian evolution. Here the cDNA cloning of MHC class II genes of the brushtail possums (Trichosurus vulpecula) is reported. The sequences obtained were found to be relatively conserved when compared to the red-necked wallaby (Macropus rufogriseus) and an South American marsupial, Monodelphis domestica. The T. vulpecula sequence shared an average overall sequence identity of 75.4% at the deduced amino acid level with M. rufogriseus and M. domestica, respectively.

Amino Acid Sequence↗
PubMed2001

Growth of specific muscle strength between 6 and 18 years in contrasting socioeconomic conditions.

The influence of sex, age, and socioeconomic conditions on specific grip strength of 6-18-year-old individuals was studied among 1,704 males and 1,956 females belonging to the so-called "Cape Coloured" community in the western part of South Africa. Half of the participants of both sexes came from communities in the Greater Cape Town area where living conditions are comparable to those of middle-class First World communities (high SES). The other half came from the poorest rural communities of Klein Karoo (low SES). Arm circumferences, triceps skinfold thickness, and grip strength of the right and of the left hand were greater in individuals from high SES at all ages. Females within each SES group had skinfolds thicker than males, especially at older ages, and were weaker. Specific grip strength (SS), estimated as grip strength per unit area of cross section of the fat-free arm, increased with age in each group, was greater in males, and was significantly lower in low SES groups, than in the high SES ones, especially during and after puberty. It seems that SES difference in SS will persist into adulthood. Sexual differences in SS can be attributed to hormonal differences; while the SS increase with age and the difference between SES groups find no clear explanation in current theories of muscle growth and development. Since the speed of neuromuscular reaction observed in our participants is slower among low SES individuals, it seems that the difference in neuromuscular control of strength may be responsible for our findings. Differences in muscle metabolism and hormonal regulation must also be considered.

Adolescent↗
PubMed2001

Molecular characterisation of the tammar wallaby (Macropus eugenii) CD3 epsilon chain cDNA.

The cDNA encoding the epsilon chain of the tammar wallaby CD3 complex (CD3epsilon) was isolated by PCR. This is the first CD3 component to be cloned in a marsupial. The tammar wallaby cDNA coding region was 61.7 and 63.0% identical to the human and mouse cDNA coding sequences, respectively. Similarly, the predicted amino acid sequence was 56.5 and 52.9% identical to the human and mouse sequences. When compared with other known CD3epsilon peptide sequences, the most conserved region of the tammar wallaby CD3epsilon chain peptide was the cytoplasmic domain and the least conserved was the extracellular portion. Phylogenetic reconstruction based on the deduced amino acid sequence placed the tammar wallaby sequence in its expected position outside of all the eutherian mammals.

Amino Acid Sequence↗
PubMed2001

Identification of canine coronavirus strains from feces by S gene nested PCR and molecular characterization of a new Australian isolate.

A nested PCR (nPCR) assay for the detection of canine coronavirus (CCV) in fecal samples is described. The target sequence for the assay was a 514-bp fragment within the spike (S) glycoprotein gene. The sensitivity of the assay is extremely high, detecting as little as 25 50% tissue culture infective doses per g of unprocessed feces. A clinical trial using dogs challenged orally with CCV SA4 and CCV NVSL was used to compare viral isolation and the nPCR assay as detection techniques over a 2-week period of infection. Virus isolation detected CCV shedding from day 4 to 9 postchallenge, while the nPCR assay detected CCV shedding from day 4 to 13 postchallenge. Cloning and sequencing of the nPCR assay product enabled investigation of the evolutionary relationships between strains within the S gene. The simple and rapid procedure described here makes this assay an ideal alternative technique to electron microscopy and viral isolation in cell culture for detection of CCV shedding in feces. The described assay also provides a method of identifying new strains of CCV without the complicated and time-consuming practice of raising antibodies to individual strains. This is illustrated by the identification, for the first time, of an Australian isolate of CCV (UWSMN-1).

Amino Acid Sequence↗
PubMed2000

Marsupial cytokines. Structure, function and evolution.

The cytokines are an important group of molecules involved in coordinating the many and varied components of the immune system. These molecules have been extensively studied in model eutherian mammals such as mice but comparatively little is known about the cytokine network of marsupials. Such information will be invaluable in elucidating fundamental aspects of the marsupial immune system and will also highlight parallels and differences between the immune systems of marsupials and eutherians. Given the importance of these goals, our groups have recently begun to tackle this lack of knowledge of the marsupial cytokine system and have met with considerable success in the face of the rapid rate of change of these proteins. This has led to the isolation of the full-length sequences encoding marsupial orthologues of tumour necrosis factor (TNF), lymphotoxins alpha and beta (LT-alpha and beta), interleukin-1 beta (IL-1beta), and interleukin-10 (IL-10). Here we review what has been learnt about structural, functional and evolutionary aspects of these marsupial cytokines as well as briefly describing more recent work in progress and future directions in this field.

Animals↗
PubMed2000

Cloning of marsupial T cell receptor alpha and beta constant region cDNAs.

Partial cDNAs encoding the tammar wallaby (Macropus eugenii) T cell receptor alpha constant region (TCRalphaC) and T cell receptor beta constant region (TCRbetaC) were obtained using reverse transcriptase-coupled polymerase chain reaction (RT-PCR). These PCR products were used to screen a brushtail possum (Trichosurus vulpecula) lymph node cDNA library, resulting in the isolation of clones containing the complete coding regions for TCRalphaC and TCRbetaC. These constitute the first marsupial T cell receptor sequences to have been elucidated. Sequence analysis of the T. vulpecula constant region revealed a considerable level of sequence identity with TCR of other species, particularly eutherian mammals, at both the nucleic acid and amino acid levels. At the nucleotide level, 65.8% sequence identity was calculated for the T. vulpecula and human TCRalphaC sequences, with 55.9% identity at the amino acid level. For TCRbetaC, the T. vulpecula and human beta1 sequence identity at the nucleotide level was 75.1% and at the amino acid level, 67.0%. Phylogenetic analyses based on the T. vulpecula sequences indicated that these sequences are basal to, but also most closely related with, TCRalphaC and TCRbetaC homologues from eutherian mammals, consistent with the current views of both mammalian and TCR evolution.

Amino Acid Sequence↗
PubMed2000

cDNA cloning of lymphotoxin alpha (LT-alpha) from a marsupial, Macropus eugenii.

Lymphotoxin (LT) is a proinflammatory cytokine with a broad spectrum of immunological activities. While the 'classic' form of the molecule is a secreted homotrimer, now referred to in the literature as LT-alpha3, it has more recently been recognised that a membrane-bound form of LT exists on activated T lymphocytes and that this represents a complex between LT-alpha and a closely related type II membrane protein, LT-beta. Together with another related cytokine, tumour necrosis factor alpha (TNF-alpha), these molecules have been extremely well studied in eutherian mammals but not in any other group. Marsupials represent a distinct branch in mammalian evolution to that of eutherians, the two groups having diverged more than 100 million years ago. We report here for the first time, the cDNA cloning of LT-alpha from a marsupial, Macropus eugenii (tammar wallaby). This sequence was found to be relatively conserved when compared to orthologous sequences from eutherian mammals, sharing an average sequence identity of 70.4% at the nucleotide level and 71.7% at the deduced amino acid level.

Amino Acid Sequence↗
PubMed1999

Severe adverse impact on sexual functioning and fertility of bone marrow transplantation, either allogeneic or autologous, compared with consolidation chemotherapy alone: analysis of the MRC AML 10 trial.

BACKGROUND: Data relating to the impact of bone marrow transplantation (BMT) on sexual functioning are equivocal; some studies have shown no major impact whereas others demonstrate a significant adverse effect on sexual health in patients treated with BMT. Further clarification is required to facilitate treatment choices and follow-up management of patients. METHODS: A cross-sectional study of sexual health and infertility was conducted in 479 patients with acute myeloid leukemia (AML) in first complete remission (CR) who were entered into the UK MRC AML 10 trial comparing allogeneic BMT (Allo-BMT), autologous BMT (A-BMT), and intensive consolidation chemotherapy (CCT). Assessment was made by patient questionnaire via the treating centers for completion and returned directly to the coordinating center. RESULTS: Both Allo-BMT and A-BMT were observed to have severe, highly significant adverse effects on the patients' sexual health. Significantly more BMT patients than CCT patients reported a decrease in interest in sex (48% vs. 24%), sexual activity (53% vs. 35%), pleasure from sex (36% vs. 18%), and ability to have sex (38% vs. 18%) (P < 0.001 in each case). Hormonal disorders and infertility also were more common in BMT patients than in CCT patients. These differences were more apparent in women and remained after adjustment for age. CONCLUSIONS: These results indicate a need to consider quality of life parameters when reviewing treatment options and to instigate effective proactive management strategies for dealing with sexual health problems in leukemia survivors.

Acute Disease↗