Search PubMed⌕ Search

Biomedical subjects

A Read

Publications and source records attributed to A Read.

At least 19 recordsLinked to original sources
PubMed2004

Genital abnormalities mimicking congenital adrenal hyperplasia in premature infants.

Unusual genital appearances in premature infants can be easily mistaken for true ambiguous genitalia, with alarming consequences. The results of blood and urine tests carried out for premature infants can be misleading due to persistence of the foetal zone of the adrenal cortex. More importantly, misdiagnosis is devastating for the parents and adds significantly to their distress. Here, we describe two patients with transient genital abnormalities and abnormal biochemical tests.

Adrenal Hyperplasia, Congenital↗
PubMed2003

Thyrotoxic, hypokalaemic periodic paralysis in Australasian men.

Abstract The present study describes the clinical and laboratory features of 11 patients with thyrotoxic, hypokalaemic periodic paralysis, presenting to five Melbourne teaching hospitals between 1991 and 2000. All 11 patients were Asian or Polynesian men aged 18-41 years, and most had experienced previous episodes of acute, unexplained paralysis. All cases resolved without significant morbidity. Thyrotoxic, hypokalaemic periodic paralysis is a potentially life-threatening and terrifying condition, which is often under-recognized and will present with increasing frequency in the community. The diagnosis should be considered in any Asian-Australian male presenting with sudden onset paralysis.

Adolescent↗
PubMed2002

Molecular genetic analysis of the NF2 gene in young patients with unilateral vestibular schwannomas.

Neurofibromatosis type 2 (NF2) must be suspected in patients presenting with a unilateral vestibular schwannoma at a young age who are therefore at theoretical risk of developing bilateral disease. We identified 45 patients aged 30 years or less at the onset of symptoms of a unilateral vestibular schwannoma. Molecular genetic analysis of the NF2 gene was completed on peripheral blood samples in all 45 and on 28 tumour samples. No pathogenic NF2 mutations were identified in any of the blood samples. NF2 point mutations were identified in 21/28 (75%) tumour samples and loss of heterozygosity (LOH) in 21/28 (75%) tumour samples. Both mutational hits were identified in 18/28 (65%) tumour samples. In one multilobular tumour, one (presumably first hit) mutation was confirmed which was common to different foci of the tumour, while the second mutational event differed between foci. The molecular findings in this patient were consistent with somatic mosaicism for NF2 and the clinical diagnosis was confirmed with the presence of two meningiomas on a follow up MRI scan. A further patient developed a contralateral vestibular schwannoma on a follow up MRI scan in whom neither of the truncating mutations in the vestibular schwannoma were present in blood. It is important when counselling patients with unilateral vestibular schwannomas to identify (1) those at risk of bilateral disease, (2) those at risk of developing other tumours, and (3) other family members at risk of developing NF2. Comparing tumour and blood DNA cannot exclude mosaicism in the index case and cannot, therefore, be used to predict those at risk of developing further tumours. However, identification of both mutations or one mutation plus LOH in the tumour and exclusion of those mutations in the blood samples of the sibs or offspring of the affected case may be sufficient to render further screening unnecessary in these relatives.

Adolescent↗
PubMed2001

The transcription factor onecut-2 controls the microphthalmia-associated transcription factor gene.

Microphthalmia-associated transcription factor (MITF) is essential for melanocyte differentiation. MITF mutations are associated with some cases of Waardenburg syndrome (WS) type 2. WS is a dominantly inherited disease characterized by auditory-pigmentary defects that result from the absence of melanocytes. The lack of mutation in MITF coding sequences in some WS2 patients suggests that unidentified factors controlling MITF expression might be involved. We show here that the cut-homeodomain transcription factor Onecut-2 (OC-2) is expressed in melanocytes and binds to the MITF gene promoter. Overexpression of OC-2 in transfected cells stimulates MITF promoter activity. Mutations that prevent OC-2 binding decrease MITF promoter activity by 75%. Based on these results, we searched in 56 WS2 patients for mutations in the OC2 gene or in OC-2 binding sites in the MITF promoter, but none was found. These results show that OC-2 stimulates MITF expression and that OC2 is a candidate gene, but not a common cause, of WS.

Animals↗
PubMed2001

Inhibitory effects during object name retrieval: the effect of interval between prime and target on picture naming responses.

Three picture naming experiments are reported which examine the relationship between the apparent inhibition of a response on one trial, and naming latency on the subsequent trial. The design of each experiment involves the presentation of prime and target pairs, either presented in succession (Lag 1 condition), or separated by two intervening unrelated trials (Lag 3 condition). A control condition is also included. In Experiment 1, a speeded picture naming task is used, and naming errors are analysed. Target pictures are misnamed at above chance rates with the name of the semantically related prime picture in the Lag 3 condition. In contrast, these prime-related errors do not occur in the Lag 1 condition, suggesting a brief inhibitory effect. If primes are briefly inhibited, then target naming latencies immediately following a related prime should be quicker than target latencies in the Lag 3 condition. Experiment 2 confirms this pattern of results, using exactly the same stimuli and design, but standard naming instructions. Experiment 3 examines whether the inferred inhibition is the result of a self-inhibitory mechanism, using a repetition priming paradigm. If Lag 1 prime representations are self-inhibited, then facilitatory effects from prime/target repetition should be stronger in the Lag 3 condition, than in the Lag 1 condition. The data from Expt 3 were not consistent with this prediction. Taken together, the results of the three experiments suggest that a brief inhibitory effect occurs after retrieval of an object name, and that the inhibition may be accomplished by mechanisms other than self-inhibition.

Adolescent↗
PubMed1999

Plasmodium chabaudi: effect of antimalarial drugs on gametocytogenesis.

The proportion of asexual blood-stage malaria parasites that develop into transmission stages (gametocytes) can increase in response to stress. We investigated whether stress imposed by a variety of antimalarial drugs administered before or during infection increased gametocyte production (gametocytogenesis) in vivo in the rodent malaria parasite, Plasmodium chabaudi. All methods of drug treatment greatly reduced the numbers of asexual parasites produced during an infection but resulted in either no reduction in numbers of gametocytes or a smaller reduction than that experienced by asexuals. We used a simple model to estimate temporal variation in gametocyte production. Temporal patterns of gametocytogenesis did not greatly differ between untreated and prophylaxis infections, with rates of gametocytogenesis always increasing as the infection progressed. In contrast, administration of drugs 5 days after infection stimulated increased rates of gametocytogenesis early in the infection, resulting in earlier peak gametocyte densities relative to untreated infections. Given the correlation between gametocyte densities and infectivity to mosquito vectors, and the high frequency of subcurative drug therapy and prophylaxis in human populations, these data suggest that antimalarial drugs may frequently have only a small effect on reducing malaria transmission and may help to explain the rapid spread of drug-resistant geno-types.

Animals↗
PubMed1999

X-inactivation and marker studies in three families with incontinentia pigmenti: implications for counselling and gene localisation.

Familial incontinentia pigmenti (IP) is an X-linked dominant disorder with an extremely variable clinical presentation. Ambiguous diagnosis can complicate genetic counselling and attempts to refine the gene location in Xq28. Marked skewing of X-inactivation patterns is a hallmark of IP and provides a means for investigating uncertain cases. We have conducted X-inactivation studies in three families where Xq28 marker studies were at odds with the original clinical assessment. The results indicate that no recombination between the disease locus and Xq28 loci has occurred and suggest that mosaicism is responsible for the discrepancy in one family.

Chromosome Mapping↗
PubMed1996

Allelic imbalance on chromosome 3p in oral dysplastic lesions: an early event in oral carcinogenesis.

We have demonstrated previously a loss of constitutional heterozygosity on the short arm of chromosome 3 in approximately 50% of oral squamous cell carcinomas. In the present study, we have investigated 30 oral dysplastic lesions (DLs), presenting clinically as either erythroplakias or leukoplakias with histopathological features of either severe epithelial dysplasia or carcinoma in situ, for LOH on chromosome 3p using 15 microsatellite markers. Thirteen of the 30 LDs (approximately 43%) showed allelic imbalance at one or more loci. The pattern of loss in these lesions defined three noncontiguous regions of interstitial deletions that overlap with those defined for oral squamous cell carcinomas. These data indicate that the alteration of tumor suppressor genes on chromosome 3p is probably an early event in oral carcinogenesis. Additionally, 7 of the 30 DLs showed microsatellite instability. However, the frequency of loci showing microsatellite instability per lesion was low.

Alleles↗
PubMed1996

Helminth immunogenetics: Why bother?

The importance of host genotype as a determinant of protective responses against helminth infection is well established. In contrast, there have been relatively few investigations of the role of helminth genotype, despite the importance accorded to the genetics of other disease-causing organisms. Here, Andrew Read and Mark Viney discuss the reasons for this oversight. They argue that it is not for any compelling empirical reason: there is at least as much evidence that worm genetics affects host protective responsiveness as there is that it does not.

Journal Article↗
PubMed1996

Reducing naltrexone-resistant hyperphagia using laser acupuncture to increase endogenous opiates.

A 28-year-old woman with acquired brain damage suffered subsequent profound mental disability and an intense hyperphagic syndrome complete with life-threatening pica. She was the single subject of two consecutive experiments. In the first, Naltrexone, an orally administered opiate blocker, was given to reduce hyperphagia and distress, but was associated with even greater urgency when eating meals and a manifest increase in distress. While distress reduced to premedication levels on withdrawal of treatment, urgency of eating did not reduce so quickly. In the second experiment a laser acupuncture procedure was used at 2.5 Hz and 10 Hz for 10 days each with an intervening 10-day placebo condition to increase the availability of the subject's endogenous opiates, and thus hopefully produce opposite effects to the first experiment and effect a positive treatment. The 10 Hz condition produced a significant but transient reduction in pica measured by attempts at pica on a supervised walk shortly after each treatment. The subject was also easier to manage on walks, and appeared happier. Further studies using physical exercise or acupressure to achieve similar or better results are discussed.

Acupuncture Therapy↗