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Biomedical subjects

R Wallace

Publications and source records attributed to R Wallace.

At least 19 recordsLinked to original sources
PubMed2006

Neuronal storage disease in a group of captive Humboldt penguins (Spheniscus humboldti).

A neuronal storage disease affecting 5 captive Humboldt penguins is described. One bird died after 3 days of lethargy and anorexia. The 4 remaining birds died after a slowly progressing course of disease with signs that included lethargy, weakness, and neurologic dysfunction. Neurologic signs included dysphagia and ataxia. Gross lesions in the first animal to die consisted of hepatosplenomegaly indicative of avian malaria, which was confirmed histologically. The 4 remaining animals were mildly to moderately emaciated. Moderate to marked vacuolation of the neuronal perikarya was observed in Purkinje cells, neurons of the brainstem nuclei, and motorneurons of the spinal cord in all birds. By electron microscopy the vacuoles represented multilayered concentric lamellar structures. These findings were indicative of sphingolipidosis. All animals had been prophylactically treated for avian malaria, aspergillosis, and possible bacterial infections with chloroquine, itraconazole, and enrofloxacin. Circumstantial evidence implicates chloroquine therapy as the possible cause of the storage disease.

Animals↗
PubMed2005

Hohlraum-driven ignitionlike double-shell implosions on the omega laser facility.

High-convergence ignitionlike double-shell implosion experiments have been performed on the Omega laser facility [T. R. Boehly, Opt. Commun. 133, 495 (1997)] using cylindrical gold hohlraums with 40 drive beams. Repeatable, dominant primary (2.45 MeV) neutron production from the mix-susceptible compressional phase of a double-shell implosion, using fall-line design optimization and exacting fabrication standards, is experimentally inferred from time-resolved core x-ray imaging. Effective control of fuel-pusher mix during final compression is essential for achieving noncryogenic ignition with double-shell targets on the National Ignition Facility [Paisner, Laser Focus World 30, 75 (1994)].

Journal Article↗
PubMed2004

Laser-driven plasma loader for shockless compression and acceleration of samples in the solid state.

A new method for shockless compression and acceleration of solid materials is presented. A plasma reservoir pressurized by a laser-driven shock unloads across a vacuum gap and piles up against an Al sample thus providing the drive. The rear surface velocity of the Al was measured with a line VISAR, and used to infer load histories. These peaked between approximately 0.14 and 0.5 Mbar with strain rates approximately 10(6)-10(8) s(-1). Detailed simulations suggest that apart from surface layers the samples can remain close to the room temperature isentrope. The experiments, analysis, and future prospects are discussed.

Journal Article↗
PubMed2004

Successful outcome following preterm abruption complicated by pancytopenia secondary to folate deficiency: important learning points.

Pancytopenia in pregnancy secondary to folate deficiency is rare, but can still occur in the UK despite improved socioeconomic status, food fortification and modern obstetric surveillance. Currently, there is considerable interest in the role of folate-homocysteine metabolism in the etiology of pregnancy disorders, and this case adds to this debate.

Abruptio Placentae↗
PubMed2004

New HLA-B alleles detected by polymerase chain reaction-sequence-specific oligonucleotide typing: HLA-B*0725, B*0728, and B*3808.

Three novel alleles, human leukocyte antigen (HLA)-B*0725, B*0728, and B*3808, were discovered during routine genotyping of samples for the Australian Bone Marrow Donor Registry and Australian Cord Blood Bank. The new alleles contain amino acid changes in the antigen-binding site of the expressed HLA protein, which may alter the antigen-binding properties of the functional protein.

Base Sequence↗
PubMed2004

Detection of a novel HLA-A allele by polymerase chain reaction-sequence-specific oligonucleotide typing: HLA-A*0252.

Anew human leukocyte antigen (HLA) class I allele, HLA-A*0252, has been found during routine typing of samples for the Australian Bone Marrow Donor Registry. A*0252 differs from A*020101 at four codon positions, with all the new polymorphisms resulting in an amino acid change. The amino acids involved are located in the antigen-binding region of the HLA protein.

Base Sequence↗
PubMed2004

A new HLA-B allele, B*1565, identified in three unrelated samples.

Anew human leukocyte antigen-B allele, B*1565, has been identified during routine typing of cord blood samples. Subsequently, two individuals from the same family as the first cord blood sample plus two unrelated Australian Bone Marrow Donor Registry samples have been found to carry this novel allele.

Amino Acid Sequence↗
PubMed2004

Identification of three novel HLA class I alleles: HLA-B*3928, HLA-B*400104 and HLA-B*4437.

Three new human leukocyte antigen (HLA) class I alleles have been identified in the Tissue Typing Laboratory in Sydney, Australia. Sequence analysis of exon 2 and exon 3 of the HLA-B gene revealed the novel polymorphism. A silent substitution of C to T at nucleotide position 369 has been identified for the HLA-B*400104 allele when compared to the closest matched allele, HLA-B*400101. The HLA-B*3928 allele was identified with a nucleotide substitution of G to C at position 362 when compared to the closest matched allele, HLA-B*390101, resulting in an amino acid substitution of Arginine to Threonine. A nucleotide substitution of C to G at position 572 resulting in the amino acid change Serine to Tryptophan was identified in the new allele HLA-B*4437, when compared to the closest matched allele HLA-B*440301. Both amino acid substitutions implicate a different specificity and affinity of antigen binding for the alleles HLA-B*3928 and HLA-B*4437.

Alleles↗
PubMed2004

Identification of new HLA-C alleles by polymerase chain reaction-sequence specific oligonucleotide typing: Cw*0314 and Cw*1511*.

In this article, we report two new human leukocyte antigen-C (HLA-C) alleles, HLA-Cw*0314 and Cw*1511, which were identified during routine tissue typing of donors for the Australian Bone Marrow Donor Registry and Australian Cord Blood Bank. HLA-Cw*0314 shows six codon changes in exon 3 compared to Cw*030401 and shares some sequence homology with Cw*07 alleles. Cw*1511 has two nucleotide changes compared with Cw*150201 in exon 2, both resulting in amino acid changes in the protein sequence.

Alleles↗
PubMed2002

Six new HLA class I alleles detected by PCR-SSO genotyping.

This paper describes six new alleles; A*0240, A*2614, B*3924, B*4425, Cw*0807 and Cw*12023, which were discovered during routine genotyping with sequence specific oligonucleotides (SSO's). Five of the new alleles have changes in residues which belong to the antigen binding site of the HLA protein. These new variants may have altered antigen binding properties and may cause differential immunological responses that could affect transplantation outcome1.

Base Sequence↗
PubMed2002

A randomised, controlled trial of cognitive and psychomotor recovery from midazolam sedation following reversal with oral flumazenil.

Flumazenil is traditionally administered intravenously to reverse the adverse effects of over sedation with benzodiazepines. The aim of this study was to test postoperative cognitive and psychomotor recovery from midazolam conscious sedation, following reversal with orally administered flumazenil. It was hypothesised that when administered by the oral route, flumazenil may enhance recovery over a prolonged period, thus increasing safety. Eighteen patients requiring intravenous midazolam sedation for dental treatment completed a randomised, double-blind, crossover trial. Following treatment the patients' sedation was reversed using either flumazenil or saline (as placebo), administered orally, on alternate appointments. Assessment of mood and cognitive function were undertaken using ClinPhone.cdr(R), a highly sensitive and specific computerised battery of cognitive tests administered by telephone prior to sedation and every hour for seven hours post reversal. Results indicate that within 20 min of administration, oral flumazenil is capable of partially reversing some cognitive and psychomotor impairments but the attentional and stimulus discrimination effects of midazolam sedation still remain.

Administration, Oral↗
PubMed2001

Efficient multi-keV underdense laser-produced plasma radiators.

Novel, efficient x-ray sources have been created by supersonically heating a large volume of Xe gas. A laser-induced bleaching wave quickly ionizes the high- Z gas, and the resulting plasma emits x rays. This method significantly improves the production of hard x rays because less energy is lost to kinetic energy and sub-keV x rays. The conversion efficiency of laser energy into L-shell radiation between 4-7 keV is measured at approximately 10%, an order of magnitude higher than efficiencies measured from solid disk targets. This higher flux enables material testing and backlighting in new regimes and scales well to future high-powered lasers.

Journal Article↗
PubMed2001

Presentations of physical illness in people with developmental disability: the example of gastro-oesophageal reflux.

People with developmental disabilities are becoming an important part of the general practice population. Although they have a similar range of medical conditions to the general population, there are some important differences in prevalence, risk factors, presentation and management of particular conditions. We use gastro-oesophageal reflux to illustrate how developmental disability may affect the presentation, assessment and management of a common condition.

Adult↗
PubMed2001

A computational model of membrane lipid electronic properties in relation to neural signaling.

We present a computational model of a transiently-organized neural membrane molecular system with possible information-processing capacity. The model examines field-induced dipole and quadrupole moments and polarizability in monomeric, dimeric, and trimeric ethenes. Polarization of the ethenes is strongly indicated. This result is interpreted as a significant electronic feature of a molecular computing system based on organization of membrane lipids into a transient ( approximately 10(-4) s) crystalline state due to lipid-protein hydrophobic mismatch at the membrane-ion-channel interface. Predictive implications of the model's electronic features are briefly discussed.

Animals↗
PubMed2001

Clinical and molecular genetics of myoclonic-astatic epilepsy and severe myoclonic epilepsy in infancy (Dravet syndrome).

The majority of severe epileptic encephalopathies of early childhood are symptomatic where a clear etiology is apparent. There is a small subgroup, however, where no etiology is found on imaging and metabolic studies, and genetic factors are important. Myoclonic-astatic epilepsy (MAE) and severe myoclonic epilepsy in infancy (SMEI), also known as Dravet syndrome, are epileptic encephalopathies where multiple seizure types begin in the first few years of life associated with developmental slowing. Clinical and molecular genetic studies of the families of probands with MAE and SMEI suggest a genetic basis. MAE was originally identified as part of the genetic epilepsy syndrome generalized epilepsy with febrile seizures plus (GEFS(+)). Recent clinical genetic studies suggest that SMEI forms the most severe end of the spectrum of the GEFS(+). GEFS(+) has now been associated with molecular defects in three sodium channel subunit genes and a GABA subunit gene. Molecular defects of these genes have been identified in patients with MAE and SMEI. Interestingly, the molecular defects in MAE have been found in the setting of large GEFS(+) pedigrees, whereas, more severe truncation mutations arising de novo have been identified in patients with SMEI. It is likely that future molecular studies will shed light on the interaction of a number of genes, possibly related to the same or different ion channels, which result in a severe phenotype such as MAE and SMEI.

Epilepsies, Myoclonic↗
PubMed2001

Caregiver report of hallucinations and paranoid delusions in elders aged 70 or older.

This study examined the demographic, medical, and psychiatric correlates of hallucinations and paranoid delusions reported by proxy informants for 822 elders aged 70 or older. This sample comprised people who were deemed unable to complete a direct interview in a large nationwide study of aging. Marital status, trouble with vision, and cognitive impairment were associated with report of both paranoid delusions and hallucinations. Depressive symptoms and stroke were associated with hallucinations only. These results suggest that inadequate external stimulation in the elderly leads to psychotic experiences.

Aged↗