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Biomedical subjects

C G Harper

Publications and source records attributed to C G Harper.

At least 19 recordsLinked to original sources
PubMed2006

Brain donation for research: strong support in Australia.

Permission by families for transplant donation has decreased in Australia. We do know that Australians are interested in donating organs. What has not been explored is how people feel about donating brain tissue for medical research. This study examines the verbal responses of the next of kin, on the day of autopsy of the deceased, to the question of brain donation for medical research. On the day of autopsy a telephone call was made to the next of kin. Families were asked to consider donating the brain tissue of the deceased to medical research. All responses were recorded. Fifty-eight per cent of families contacted by telephone gave permission for the brain donation. The main reasons given for donating the brain to research were wanting to help others, and the family knowing the deceased's wishes. This is an excellent response from families and more encouraging than the literature would predict. Further education and awareness about brain donation is needed and may be achieved effectively by combining donation options with the Australian Organ Donor Register.

Australia↗
PubMed2004

Characterization of gabaergic neurons within the human medial mamillary nucleus.

The morphology, distribution and relative frequency of GABAergic neurons in the medial mamillary nucleus (MMN) of normal human individuals was studied using a glutamic acid decarboxylase (GAD) antiserum. GAD-immunoreactive (GAD-IR) neurons were found sparsely distributed throughout the MMN and most displayed a simple bipolar morphology. A small population of large diameter GAD-IR neurons was found in the white matter capsule adjacent to the ventral border of the MMN. Results of double-labeling experiments revealed no evidence of calretinin, parvalbumin or calbindin immunoreactivities co-localizing with GAD-IR neurons. GAD-IR neurons of the MMN had an average somal area of 138+/-41 microm2, compared with the average somal area of 384+/-137 microm2 for the population of MMN neurons as a whole. GAD-IR neurons had a tendency to cluster in groups of two (and occasionally three) and showed a distribution gradient across the MMN with higher densities being found near the insertion of the fornix, the origin of the mamillo-thalamic tract and toward the medial MMN border. Quantitative estimates of GAD-IR neuron frequency revealed the GAD-IR phenotype to constitute an average of 1.7% percent of the total neuron population within the human MMN. These findings suggest that inhibitory activity within the human MMN is regulated in part by a small population of intrinsic GABAergic interneurons.

Adult↗
PubMed2004

Association studies of neurotransmitter gene polymorphisms in alcoholic Caucasians.

Ethanol enhances mesolimbic/cortical dopamine activity in reward and reinforcement circuits. We investigated the hypothesis that risk for alcoholism may be mediated by genes for neurotransmitters associated with the dopamine reward system as well as genes for enzymes involved in ethanol metabolism. DNA was extracted from brain tissue collected at autopsy from pathologically characterized alcoholics and controls. PCR-based assays showed that alcoholism was associated with polymorphisms of the dopamine D2 receptor (DRD2) TaqI B (P = .029) and the GABAA-beta2 subunit C1412T (P = .012) genes, but not with the glutamate receptor subunit gene NMDAR2B (366C/G), the serotonin transporter gene (5HTTL-PR), the dopamine transporter gene DAT1(SLC6A3), the dopamine D2 receptor gene DRD2 TaqI A, or the GABAA alpha1(A15G), alpha6(T1519C), and gamma2(G3145A) subunit genes. The glial glutamate transporter gene EAAT2 polymorphism G603A was associated with alcoholic cirrhosis (P = .048). The genotype for the most active alcohol dehydrogenase enzyme ADH1C was associated with a lower risk of alcoholism (P = .026) and was less prevalent in alcoholics with DRD2TaqIA2/A2 (P = .047), GABAA-beta2 1412C/C (P = .01), or EAAT2 603G/A (P = .022) genotypes. Combined DRD2TaqI A or B with GABAA-beta2 or EAAT2 G603A genotypes may have a concerted influence in the predisposition to alcoholism.

Alcoholism↗
PubMed2003

Amyloidoma of a spinal root.

A unique case of amyloidoma presenting as a dumbbell-shaped tumor of a spinal root without bony erosion is described. Amyloid was also present in the facial nerve. DNA analysis for transthyretin was negative. Isolated amyloid fibers contained lambda light chains, and although plasma and urine immunoelectrophoresis performed by immunofixation was normal, it is possible the tumor may have been derived from an isolated plasmacytoma.

Amino Acid Sequence↗
PubMed2002

Banking for the future: an Australian experience in brain banking.

The New South Wales (NSW) Tissue Resource Centre (TRC) has been set up to provide Australian and international researchers with fixed and frozen brain tissue from cases that are well characterised, both clinically and pathologically, for projects related to neuropsychiatric and alcohol-related disorders. A daily review of the Department of Forensic Medicine provides initial information regarding a potential collection. If the case adheres to the strict inclusion criteria, the pathologist performing the postmortem examination is approached regarding retention of the brain tissue. The next of kin of the deceased is then contacted requesting permission to retain the brain for medical research. Cases are also obtained through donor programmes, where donors are assessed and consent to donate their brain during life. Once the brain is removed at autopsy, the brain is photographed, weighed and the volume determined, the brainstem and cerebellum are removed. The two hemispheres are divided, one hemisphere is fresh frozen and one fixed (randomised). Prior to freezing, the hemisphere is sliced into 1-cm coronal slices and a set of critical area blocks is taken. All frozen tissues are kept bagged at -80 degrees C. The other hemisphere is fixed in 15% buffered formalin for 2 weeks, embedded in agar and sliced at 3-mm intervals in the coronal plane. Tissue blocks from these slices are used for neuropathological analysis to exclude any other pathology. The TRC currently has 230 cases of both fixed and frozen material that has proven useful in a range of techniques in many research projects. These techniques include quantitative analyses of brain regions using neuropathological, neurochemical, neuropharmacological and gene expression assays.

Autopsy↗
PubMed2002

Helicobacter cetorum sp. nov., a urease-positive Helicobacter species isolated from dolphins and whales.

A novel helicobacter with the proposed name Helicobacter cetorum, sp. nov. (type strain MIT 99-5656; GenBank accession number AF 292378), was cultured from the main stomach of two wild, stranded Atlantic white-sided dolphins (Lagenorhynchus acutus) and from the feces of three captive cetaceans (a Pacific white-sided dolphin [Lagenorhynchus obliquidens]; an Atlantic bottlenose dolphin [Tursiops truncatus]; and a beluga whale [Delphinapterus leucas]). The infected captive cetaceans were either subclinical, or clinical signs included intermittent regurgitation, inappetance, weight loss, and lethargy. Ulcers were observed in the esophagus and forestomach during endoscopic examination in two of the three captive animals. In the third animal, esophageal linear erosions were visualized endoscopically, and histopathological evaluation of the main stomach revealed multifocal lymphoplasmacytic gastritis with silver-stained spiral-shaped bacteria. Helicobacter cetorum is a fusiform gram-negative bacterium with a single bipolar flagellum. The isolates grow under microaerobic conditions at 37 and 42 degrees C but not at 25 degrees C. H. cetorum is urease, catalase, and oxidase positive, and it is sensitive to cephalothin. The isolates from the wild, stranded dolphins were sensitive to nalidixic acid, whereas the isolates from the collection animals were resistant. By 16S rRNA sequencing it was determined that H. cetorum represented a distinct taxon that clusters most closely with H. pylori. Further studies are necessary to determine the role of H. cetorum in the development of gastric ulcers and gastritis of cetaceans. This is the first description and formal naming of a novel Helicobacter species from a marine mammal.

Animals↗
PubMed2001

Quantitative analysis of glutamic acid decarboxylase-immunoreactive neurons in the anterior thalamus of the human brain.

Local circuit neurons in the human anterior thalamus (AT) were identified on the basis of glutamic acid decarboxylase immunoreactivity (GAD-IR). GAD-IR neurons of the AT displayed small diameter somas with thin, sparsely-branching dendrites, consistent with the morphological characteristics of local circuit neurons found in the thalami of other mammals. Sampling techniques revealed an average of 42% of all neurons within the AT were GAD-IR, one of the highest reported percentages of local circuit neurons in the mammalian thalamus. The presence of high proportion of local circuit neurons in the AT may indicate the extent to which the Papez circuit has evolved within the human brain in comparison to other mammals.

Adult↗
PubMed2001

Repeated prenatal corticosteroid administration delays myelination of the corpus callosum in fetal sheep.

Glucocorticoids regulate oligodendrocyte maturation and the myelin biosynthetic pathways. Synthetic glucocorticoids, the corticosteroids have been successfully used in clinical practice as a single course to enhance lung maturation and reduce mortality and morbidity in preterm infants with no long-term neurologic or cognitive side effects. However, a trend has arisen to use repeated courses despite an absence of safety data from clinical trials. We examined the effects of clinically appropriate, maternally administrated, repeated courses of corticosteroids on myelination of the corpus callosum using sheep as a large animal model. The corpus callosum is a major white matter tract that undergoes protracted myelination, underpins higher order cognitive processing and developmental damage to which is associated with, for example, cerebral palsy, mental retardation and attention deficit hyperactivity disorder. Pregnant ewes were given saline or betamethasone (0.5 mg/kg) at 104,111,118 and 124 days gestation, stages equivalent to the third trimester in humans. Lambs were delivered at 145 days (term), perfused and the corpus callosum examined light and electron microscopically. Total axon numbers were unaffected (P>0.05). However, myelination was significantly delayed. Myelinated axons were 5.7% in the experimental group and 9.2% in controls (P<0.05); conversely, unmyelinated axons were 88.3 and 83.7% (P<0.05). Myelinated axon diameter and myelin sheath thickness were also reduced (0.68 vs. 0.94 and 0.11 vs. 0.14 microm, P<0.05). Our data suggest that repeated prenatal corticosteroid administration delays myelination of the corpus callosum and that further safety data are needed to evaluate clinical practice.

Agenesis of Corpus Callosum↗
PubMed2001

Repeated prenatal corticosteroid administration delays astrocyte and capillary tight junction maturation in fetal sheep.

Glucocorticoids are powerful regulators of cell differentiation and maturation. Their synthetic counterparts, the corticosteroids, are used widely in obstetric practice to enhance fetal lung maturation in cases of threatened preterm birth. Here we examined the effects of repeated corticosteroid administration on astrocyte and capillary tight junction development in the fetal sheep brain, selecting the corpus callosum for analysis. Pregnant ewes were given saline or betamethasone (0.5 mg/kg) at 104, 111, 118 and 124 days gestation. Lambs were delivered at term, terminally anaesthetized and transcardially perfused. Transverse semi-thin sections of the corpus callosum were cut and immuno-stained with antibody against glial fibrillary acidic protein (GFAP). Ultra-thin sections were examined in the electron microscope. The percentage area of GFAP staining was reduced in the corticosteroid-treated group compared to control (5.2 vs. 8.7%, P<0.05). The expression of GFAP in peri-capillary and parenchymal astrocytes was also reduced compared to control (peri-capillary: 3.0 vs. 9.5 microm2; parenchymal: 14.6 vs. 29.4 microm2, P<0.05). Furthermore, capillary tight junction maturation was delayed compared to control. Immature 'type II' junctions were more common in the corticosteroid-treated group (63 vs. 22%, P<0.05), whereas more mature 'type III' junctions were less common (27 vs. 65%, P<0.05). Our data suggest that repeated corticosteroids delay both astrocyte and capillary tight junction maturation. The implications for clinical practice are as yet unknown.

Animals↗
PubMed2001

Intracavernous schwannoma of the abducens nerve: a review of the clinical features, radiology and pathology of an unusual case.

We report a case of an intracavernous abducens nerve schwannoma presenting in a 19 year old male of Mediterranean origin. This is only the second report of an abducens nerve schwannoma located entirely within the cavernous sinus. The lesion resulted in a progressive diplopia and focal abducens palsy. The clinical, radiological and pathological features are presented. A literature search has identified only four other abducens nerve schwannomas arising completely or partly within the cavernous sinus. We review these cases and aspects of other ocular cranial nerve schwannomas.

Abducens Nerve Diseases↗
PubMed2001

Spinal chloroma presenting with triplegia in an aleukaemic patient.

Malignant myeloid blast cells may occasionally form a solid mass in tissues outside the haemopoietic system. These tumours are known as chloromas or granulocytic sarcomas. Chloromas occur most commonly in the context of acute myelogenous leukaemia but, rarely, they occur in the absence of other haematological disease, and may be misdiagnosed as lymphoma. A case of a previously well 35-year-old woman presenting with rapidly progressive triplegia caused by a paraspinal and extradural cervical chloroma with no evidence of bone marrow or other haematological involvement is described. Few cases of spinal cord compression caused by chloroma in otherwise healthy patients have been reported. Morphological features of myeloid differentiation, histochemistry and immunohistochemistry, may all aid in rapid diagnosis and allow early and appropriate therapy.

Adult↗
PubMed2000

Increased levels of expression of an NMDARI splice variant in the superior temporal gyrus in schizophrenia.

Expression patterns of mRNAs for the NMDARI subunit (NRI) carboxy-terminus isoforms were investigated in postmortem brain tissue using isotopic in situ hybridization. Three brain regions (superior temporal, middle frontal and visual cortices) were examined in patients with schizophrenia (n = 6) and control subjects (n = 6). A 22% higher level of expression of the NRI isoform that contains neither spliced exon was observed in the superior temporal gyrus of patients with schizophrenia compared with controls (p = 0.01). No differences were observed in the expression of the other isoforms in the three regions studied. These data suggest that NRI alternative splicing might be abnormal in schizophrenia and reinforce previous findings implicating the superior temporal gyrus as a site of neural dysfunction in schizophrenia.

Adult↗
PubMed2000

Parvalbumin-immunoreactive neurons in the human anteroventral thalamic nucleus.

We immunohistochemically characterised the expression of the calcium-binding protein parvalbumin in the normal human anteroventral thalamic nucleus (AVN). Two morphologically distinct neuronal populations were found to be parvalbumin-immunoreactive (PV-IR): a large population of lightly staining PV-IR neurons and a smaller population of intensely PV-IR neurons. This second type of neuron, which displayed many characteristics normally associated with GABAergic interneurons, has not previously been described in human thalamus. Thus, presumptive thalamic interneurons in the human brain can be further subtyped on the basis of immunoreactivity to parvalbumin. This may have implications for the understanding of thalamocortical function in the normal state and in dysfunctional conditions such as Wernicke-Korsakoff syndrome and schizophrenia.

Adult↗
PubMed2000

Heroin-related deaths in Sydney, Australia. How common are they?

The objective of this article was to determine the number of recent deaths caused by accidental illicit drug overdoses seen at the NSW Institute of Forensic Medicine, Glebe (Sydney). All Forensic cases (3559) were reviewed during the period July 1995-February 1997. Any that were classified as accidental illicit drug overdose were followed up, and demographic and toxicological data were collected for analysis. Our results found that one hundred and forty three accidental illicit drug overdoses were identified from 3359 autopsies during the 20 month data collection period (4%). Male to female ratio was 5:1, but females predominated in the methadone toxicity group. Most of the cases were under 40 years of age. Toxicological results showed that 80% of the deaths were associated with morphine (heroin) levels in the toxic range, although 91% had morphine present at some level. Only 35% of cases had significant levels of bile morphine, suggesting "chronic" usage. In many cases, multiple illicit substances and/or alcohol were thought to be important contributing factors. Cocaine was found in 13% of cases, and all of these had morphine (heroin) in their blood. Methadone was found in 13% of cases, and 13/19 had toxic levels--9/19 also had morphine in their blood. Only two cases had amphetamines or methamphetamines in their blood. The authors conclude that Heroin overdose is by far the most common cause of accidental illicit drug overdose. Those at greatest risk are naive users and those who are not tolerant. There is an urgent need for increased awareness and further education concerning the dangers of heroin use, particularly of multiple drug use (including alcohol). Only about one-third of these cases appear to be "chronic" users.

Adult↗
PubMed1999

Neuronal loss in functional zones of the cerebellum of chronic alcoholics with and without Wernicke's encephalopathy.

This study examines the effect of chronic alcohol consumption on the human cerebellum using operational criteria for case selection [Caine D. et al. (1997) J. Neurol. Neurosurg. Psychiat. 62, 51-60] and unbiased stereological techniques. We describe, for the first time, structural changes in different functional zones of the cerebellum of chronic alcoholics and correlate these changes with specific clinical symptoms. No consistent changes in the number of neurons or the structural volume for any cerebellar region were observed in the chronic alcoholics without the clinical signs of Wernicke's encephalopathy. In all cerebellar measures, these chronic alcoholics did not differ significantly from the non-alcoholic controls, suggesting that chronic alcohol consumption per se does not necessarily damage human cerebellar tissue. However, several cerebellar changes were noted in the thiamine-deficient alcoholics studied. There was a significant decrease in Purkinje cell density (reduced on average by 43%) and molecular layer volume (reduced by 32%) in the cerebellar vermis in all thiamine-deficient chronic alcoholics. A decrease in cell density and atrophy of the molecular layer, where the dendritic trees of the Purkinje cells are found, without significant cell loss suggests loss of cellular dendritic structure and volume. These thiamine-deficient alcoholics also had a significant decrease (36% loss) in the estimated Purkinje cell number of the flocculi, disrupting vestibulocerebellar pathways. These results indicate that cerebellar Purkinje cells are selectively vulnerable to thiamine deficiency. There is evidence that this damage contributes significantly to the clinical signs of Wernicke's encephalopathy. There was a 36% loss of Purkinje cells in the lateral lobe in alcoholics with mental state signs and 42% atrophy of vermal white matter in ataxic alcoholics. The finding of a 57% loss of Purkinje cells and a 43% atrophy of the molecular layer of the vermis in alcoholics with cerebellar dysfunction supports previous findings highlighting the importance of spinocerebellar pathways to these symptoms.

Adult↗
PubMed1999

Hepatocellular carcinoma metastasizing to the orbit diagnosed by fine needle aspiration cytology.

Hepatocellular carcinoma (HCC) rarely metastasizes to the orbit. We report a case of a 78-year-old man with a past history of HCC, who presented with a periorbital mass, which was diagnosed as metastatic HCC by fine needle aspiration cytology (FNAC) and subsequently confirmed on excision biopsy. The cytological, histopathological and immunohistochemical findings are presented and the differential diagnosis is discussed. To our knowledge there has been no previously reported case of HCC metastatic to the orbit diagnosed by FNAC.

Aged↗