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Biomedical subjects

D Sheedy

Publications and source records attributed to D Sheedy.

9 recordsLinked to original sources
PubMed2006

Differential protein expression in the prefrontal white matter of human alcoholics: a proteomics study.

Neuroimaging and post-mortem studies indicate that chronic alcohol use induces global changes in brain morphology, such as cortical and subcortical atrophy. Recent studies have shown that frontal lobe structures are specifically susceptible to alcohol-related brain damage and shrinkage in this area is largely due to a loss of white matter. This may explain the high incidence of cognitive dysfunction observed in alcoholics. Using a proteomics-based approach, changes in protein expression in the dorsolateral prefrontal region (BA9) white matter were identified in human alcoholic brains. Protein extracts from the BA9 white matter of 25 human brains (10 controls; eight uncomplicated alcoholics; six alcoholics complicated with hepatic cirrhosis; one reformed alcoholic) were separated using two-dimensional gel electrophoresis. Overall, changes in the relative expression of 60 proteins were identified (P<0.05, ANOVA) in the alcoholic BA9 white matter. In total, 18 protein spots have been identified using MALDI-TOF; including hNP22, alpha-internexin, transketolase, creatine kinase chain B, ubiquitin carboxy-terminal hydrolase L1 and glyceraldehyde-3-phosphate dehydrogenase. Several of these proteins have been previously implicated in alcohol-related disorders and brain damage. By identifying changes in protein expression in this region from alcoholics, hypotheses may draw upon more mechanistic explanations as to how chronic ethanol consumption causes white matter damage.

Adult↗
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↗
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

Size of mamillary bodies in health and disease: useful measurements in neuroradiological diagnosis of Wernicke's encephalopathy.

BACKGROUND: As the resolution of noninvasive neuroimaging techniques improves, small structures such as the mamillary bodies can be visualized and measured. The mamillary bodies are pathologically small in a number of neurological disorders, the most common and important is chronic Wernicke's encephalopathy (WE), or the Wernicke-Korsakoff syndrome (WKS), as it is often called. This disorder is caused by vitamin B1 deficiency (thiamin) and is seen most commonly in people who drink excessive amounts of alcohol. The disorder is easily preventable by using oral or parenteral thiamin. The aim of this study was to establish a range for the volume of the mamillary bodies in normal and in various disease states, particularly WE. METHODS: Brains were taken from 2212 sequential autopsies performed at the New South Wales Institute of Forensic Medicine from 1996 through 1997. After fixation in 10% formalin, the brains were sectioned coronally and a block containing the mamillary bodies was dissected. The maximum vertical and transverse diameters of the mamillary bodies were measured using Mitutoyo vernier callipers and the volume calculated (V = 4/3 (a2b), where a and b are the vertical and transverse radii, respectively). RESULTS: There were 164 cases with significant pathological changes in the mamillary bodies. These included cases with WE (25), Alzheimer's discase (10), infarction (11), and trauma (55). All but two of the WE cases were chronic or acute on chronic. The mean volume of the mamillary bodies was reduced by 60% in cases with chronic WE and by 25% in cases with Alzheimer's disease. In normal cases, there was a significant age-related reduction in volume, and males had larger mamillary bodies than females. Cases with alcoholic cirrhosis of the liver had normal mamillary body volumes. CONCLUSIONS: There is a gross shrinkage of the mamillary bodies in cases of chronic WE, but clinicians need to consider other diagnoses, such as Alzheimer's disease, which can also result in shrinkage. These quantitative data will be helpful in the neuroradiological diagnosis of some of these disorders, particularly WE.

Adolescent↗
PubMed1998

Direct isolation and analysis of endogenous transjunctional ADP from Cx43 transfected C6 glioma cells.

Gap junctional communication has been implicated in numerous cellular processes. However, the repertoire of specific transjunctional substances which mediate these processes remains relatively unexplored. A few selected secondary messengers have been identified, at least indirectly (e.g., cAMP and IP3) and phenotypic complementation experiments have indicated that gap junctions enable communicating cells to distribute nucleotide pools as a shared resource. The latter would include high energy compounds such as ADP and ATP, allowing cells to share energy resources. We have utilized a nonbiased process to directly capture, identify, and quantify transjunctional compounds from C6 glioma cells, the transformed phenotype of which has been ameliorated by transfection with connexin43 (Cx43). This technique involves the direct isolation, identification, and quantitation of radioactive transjunctional molecules that travel from metabolically labeled "donor" cells to "receiver" cells. This report demonstrates that ADP and/or ATP represents over 6% of the transjunctional material derived from glucose in Cx43-transfected C6 glioma cells. Furthermore, equilibration of these high energy metabolites among first order neighbors is shown to occur in less than 20 min of communication.

Adenosine Diphosphate↗
PubMed1982

In vitro effects of 4-hydroperoxycyclophosphamide on human immunoregulatory T subset function. I. Selective effects on lymphocyte function in T-B cell collaboration.

The alkylating agent cyclophosphamide may suppress or enhance immune responses in vivo but is inactive in vitro unless metabolized by microsomal enzyme activation. 4-hydroperoxycyclophosphamide (4-HC) is a synthetic compound that is spontaneously converted in aqueous solution to the active metabolites. In this report, we examined the in vitro sensitivity of functional human T cell subsets to 4-HC in a polyclonal B cell differentiation assay and in the generation of mitogen-induced suppressor cells for effector B cell function. Con A-induced T suppression of B cell differentiation is completely abrogated by a 1-h pretreatment of T cells at very low concentrations of between 10(-2) and 20 nmol/ml, whereas inducer T cell function is sensitive only to concentrations in greater than 40 nmol/ml. The effects of 4-HC on suppressor T cells appear to occur at concentrations that do not result in DNA cross-linking or decreased blastogenesis. Con A-induced T suppressors are generated from within the OKT4+, OKT8- subset and are sensitive to low-dose 4-HC only before activation, whereas differentiated suppressor cells are resistant to concentrations in greater than 80 nmol/ml. Low-dose 4-HC pretreatment of the B cell population results in abrogation of immunoglobulin secretion when treated B cells are cocultured with unfractionated T cells, however, this effect is completely reversible if pretreated B cells are cocultured with T cells devoid of suppressor activity. These results demonstrate that human presuppressor cells for B-effector function differentiate in response to Con A from the OKT4+, OKT8- subset and are exquisitely sensitive to low concentrations of CYP whereas mature suppressor and inducer functions are resistant to all but very high concentrations in vitro. The differential sensitivity of functional T and B cell subsets to 4-HC in vitro can be a very useful probe in dissecting immunoregulatory interactions with man.

B-Lymphocytes↗
PubMed1982

Identification of the T cell subset that produces human gamma interferon.

Positive and negative selection procedures combined with cytofluorographic analysis and lysis with monoclonal antibodies were utilized to identify the T lymphocyte subset that produces human gamma interferon (gamma-IFN) (formerly referred to as "immune" or "type II" interferon) in response to mitogen stimulation. Lymphocytes were separated on the basis of their Fc receptors for IgG or IgM, their nonreactivity with IgM or IgG antibodies, and their reactivity with the monoclonal antibodies OKT4, OKT8, OKT11a, and OKM1. Isolated T cell subsets were incubated with the gamma-IFN inducer, phytohemagglutinin. Three days after induction, the cell supernatants were harvested and assayed for interferon. The T cell subset that produces gamma-IFN was identified as E rosette positive with the phenotype: T gamma, T non-micro, OKM1+, OKT4-, OKT8- and OKT11a+. gamma-IFN production by cells was resistant to doses of x-irradiation that abrogate mitogen-induced T suppressor function but was highly sensitive to low doses of 4-hydroperoxycyclophosphamide. These data demonstrate that gamma-IFN is produced by the T gamma, OKM1+ lymphocyte subset, but these cells may also require the presence of accessory monocytes for elaboration of gamma-IFN. The anti-proliferative activity of gamma-IFN may be responsible for the previously described suppressor function of this subset, and gamma-IFN production by T gamma cells may distinguish this subset from the suppressor/cytotoxic functions of the OKT8+ subset or the mitogen-induced OKT4+ suppressor.

Antibodies, Monoclonal↗
PubMed1981

Immunoregulatory T cell function in multiple myeloma.

Multiple myeloma is a malignancy characterized by uncontrolled monoclonal B cell differentiation and immunoglobulin production. In most instances, there is concomitant reduction in polyclonal differentiation and immunoglobulin synthesis both in vivo and in vitro. In in vitro pokeweed mitogen-induced B cell differentiation assays, proliferation and polyclonal immunoglobulin secretion optimally requires T cell help and can be inhibited both by monocytes and suppressor T cells. Helper function and monocyte-mediated suppression are relatively radio-resistant whereas T suppressor function is sensitive to 2,000 rad x-irradiation. We have examined myeloma T cell subset function in this assay using recombinations of isolated patient and normal B cells, T cells, and T cell subsets. Monocytes were removed by a carbonyl iron ingestion technique, normal and myeloma T cells were fractionated on the basis of Fc receptors for immunoglobulin (Ig) G (Tgamma) or IgM (Tmu or T non-gamma), and proliferation and IgG secretion after co-culture determined by [(3)H]thymidine incorporation and radio-immunoassay, respectively. Myeloma B cells demonstrate quantitatively and qualitatively normal blastogenic responses and are appropriately regulated by either autologous or allogeneic T helper and suppressor subsets. Despite normal proliferation, however, myeloma B cells remain deficient in subsequent differentiation and immunoglobulin secretion even when co-cultured in the absence of monocytes or suppressor T cells and the presence of normal helper cells. Myeloma T cell populations, in contrast, are entirely normal in helper capacity over a range of T:B ratios but are markedly deficient in radiosensitive and concanavalin A-induced suppressor activity. T suppressor cell dysfunction in multiple myeloma is apparently due to a deficit in the T non-gamma suppressor subset, whereas Tgamma cells, although proportionately reduced, are functionally normal. This unique T suppressor deficit reflects the heterogeneity of suppressor mechanisms in this disease and may represent a compensatory response to the monoclonal proliferation or the involvement of regulatory T cells in the pathogenesis of the malignancy.

Antigens, Surface↗