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A Thrasher

Publications and source records attributed to A Thrasher.

15 recordsLinked to original sources
PubMed2001

Measuring threshold shifts for brain stimulation reward using the method of limits.

Thresholds determined from the frequency of pulses and the current for rewarding brain stimulation were obtained from rats with lateral hypothalamic electrodes. The threshold, defined as the frequency or current corresponding to one-half the maximum response rate, was interpolated from reward summation functions. Daily trials of both ascending and descending sequences of frequency and current yielded no significant difference between order of presentation. While there was more variability in the maximum response rates across the sessions, neither frequency- nor current-based threshold evaluations yielded significant rate effects. Our findings suggest that the threshold procedure is generally not influenced by the sequence of delivery of stimulus values and, thus, may be regarded as a reliable measure of the reinforcing properties of brain-stimulation reward.

Analysis of Variance↗
PubMed2000

Intrinsic defects of B cell function in X-linked severe combined immunodeficiency.

The cytokine receptor common gamma chain mutation in X-linked SCID results in a failure of T and NK cell development and an as yet undefined defect of B cells. Using immunoglobulin isotype-specific reverse transcription-PCR we show that although hematopoietic stem cell transplantation restores a diverse repertoire of class-switched B cell clones, on further analysis these are almost all of donor origin. This suggests that host B cells, which predominate after unconditioned transplantation, are still defective even in the presence of normal T cells. These studies imply that effective humoral reconstitution can only be achieved by the engraftment of normal donor B cells.

B-Lymphocytes↗
PubMed2000

Diagnosis of X-linked lymphoproliferative disease by analysis of SLAM-associated protein expression.

X-linked lymphoproliferative disease (XLP) is an inherited immunodeficiency in which affected boys show abnormal responses to Epstein-Barr virus infection. The gene defective in XLP has been identified and designated SH2D1A and encodes a protein termed SLAM-associated protein (SAP). Mutation analysis in individuals with typical XLP presentations and family histories has only detected abnormalities in approximately 60% of patients. Thus, genetic analysis alone cannot confirm a diagnosis of XLP We have developed a SAP expression assay that can be used as a diagnostic indicator of XLP We show that SAP is constitutively expressed in normal individuals, in patients with severe sepsis and in patients with other primary immunodeficiencies. In six XLP patients, four with classical and two with atypical presentations, SAP expression was absent. In the latter two, who were previously assigned as having common variable immunodeficiency (CVID), the diagnosis of XLP was initially made using the protein expression assay. In two further patients in whom no mutation could be detected by genetic analysis, lack of SAP expression strongly suggests that these individuals have XLP. We therefore suggest that XLP should be suspected in certain boys previously diagnosed as having CVID and recommend that patients are investigated both by genetic analysis of SH2D1A and by expression of SAP protein.

Agammaglobulinemia↗
PubMed1998

Enhanced retroviral transduction of 5-fluorouracil-resistant human bone marrow (stem) cells using a genetically modified packaging cell line.

Pluripotent hematopoietic stem cells (PHSC) are rare cells capable of multilineage differentiation, long-term reconstituting activity and extensive self-renewal. Such cells are the logical targets for many forms of corrective gene therapy, but are poor targets for retroviral mediated gene transfer owing to their quiescence, as retroviral transduction requires that the target cells be cycling. To try and surmount this problem we have constructed a retroviral producer line that expresses the membrane-bound form of human stem cell factor (SCF) on its cell surface. These cells are capable, therefore, of delivering a growth signal concomitant with recombinant retroviral vector particles. In this report we describe the use of this cell line to transduce a highly quiescent population of cells isolated from adult human bone marrow using the 5-fluorouracil (FU) resistance technique of Berardi et al. Quiescent cells selected using this technique were transduced by cocultivation with retroviral producers expressing surface bound SCF or with the parent cell line that does not. Following coculture, the cells were plated in long-term bone marrow culture for a further 5 weeks, before plating the nonadherent cells in semisolid media. Colonies forming in the semisolid media over the next 14 days were analyzed by polymerase chain reaction for the presence of the retroviral vector genome. Over six experiments, the transduction frequency of the quiescent 5-FU resistant cells using the SCF-expressing producer line averaged about 20%, whereas those transduced using the parent producer line showed evidence of reduced levels or no transduction.

Adult↗
PubMed1995

Familial disseminated atypical mycobacterial infection in childhood: a human mycobacterial susceptibility gene?

Inherited defects in specific components of the immune system have provided many clues to the immunological mechanisms underlying resistance to microbial infection. We report a familial immune defect predisposing to disseminated atypical mycobacterial infection in childhood. 6 children with disseminated atypical mycobacterial infection and no recognised form of immunodeficency were identified. Four, including two brothers, come from a village in Malta, and two are brothers of Greek Cypriot origin. They presented with fever, weight loss, lymphadenopathy, and hepatosplenomegaly. They had anaemia and an acute phase response. A range of different mycobacteria (Mycobacterium fortuitum, M chelonei, and four strains of M avium intracellulare complex) were isolated. Treatment with multiple antibiotics failed to eradicate the infection, although treatment with gamma interferon was associated with improvement. Three have died and the surviving children have chronic infection. Tumour necrosis factor-alpha production in response to endotoxin and gamma-interferon was found to be defective in affected patients and their parents. T-cell proliferative responses to mycobacterial and recall antigens were reduced in parents of affected children and gamma-interferon production was diminished in the affected patients and their parents. Clinical and immunological features suggest that these patients are phenotypically similar to Lsh/Ity/Bcg susceptible mice. Understanding of this defect may provide insights into the mechanisms responsible for susceptibility to mycobacteria.

Adult↗
PubMed1993

Cerebral aspergilloma in a child with autosomal recessive chronic granulomatous disease.

A 2 year old girl presented with epilepsy 16 months after being diagnosed as having autosomal recessive chronic granulomatous disease. Computed tomography showed a cerebral mass which was surgically removed and proved histologically to be an aspergilloma. This case illustrates the application of molecular diagnostic techniques to the diagnosis of chronic granulomatous disease. The occurrence of, and unusual reaction to, cerebral aspergillus infection indicates the need to consider this possibility in the differential diagnosis of mass lesions in chronic granulomatous disease. Furthermore, it is clear that autosomal recessive chronic granulomatous disease cannot be considered to be a clinically mild form that is exempt from major neurological complications.

Aspergillosis↗
PubMed1993

Chronic granulomatous disease: towards gene therapy.

Failure of a superoxide generating system, the NADPH oxidase, present in neutrophils and other phagocytes gives rise to chronic granulomatous disease (CGD), a group of single gene inherited disorders all characterised by an extreme susceptibility to pyogenic infection, with potentially fatal consequences. About 30% of CGD cases are due to an autosomally inherited deficiency of a 47 kDa cytoplasmic component of the oxidase (p47-phox). Epstein-Barr virus (EBV) immortalised B-lymphocyte lines established from these CGD patients also express this NADPH oxidase defect and consequently are rendered incapable of generating superoxide on stimulation. We have utilised a p47-phox-deficient EBV-transformed B cell line as a recipient for retroviral transfer of a functional p47-phox cDNA. The presence and activity of the retrovirally encoded p47-phox in the transduced cells is demonstrated and we show that this restores their capacity to generate superoxide.

B-Lymphocytes↗
PubMed1992

Restoration of superoxide generation to a chronic granulomatous disease-derived B-cell line by retrovirus mediated gene transfer.

Failure of a superoxide generating system, the NADPH oxidase, present in neutrophils and other phagocytes gives rise to chronic granulomatous disease (CGD), a group of single-gene inherited disorders all characterized by an extreme susceptibility to pyogenic infection, with potentially fatal consequences. About 30% of CGD cases are caused by an autosomally inherited deficiency of a 47-Kd cytoplasmic component of the oxidase (p47-phox). Epstein-Barr virus (EBV) immortalized B-lymphocyte lines established from these CGD patients also express this NADPH oxidase defect and consequently are rendered incapable of generating superoxide on stimulation. We have used a p47-phox-deficient EBV-transformed B-cell line as a recipient for retroviral transfer of a functional p47-phox cDNA. The presence and activity of the retrovirally encoded p47-phox in the transduced cells is demonstrated and we show that this restores their capacity to generate superoxide.

B-Lymphocytes↗
PubMed1982

Ultrastructural visualization of complex carbohydrates in eosinophilic leukocytes.

Complex carbohydrates in eosinophils from human, rabbit, and rat marrow were identified and localized by cytochemical and radioautographic methods. The high iron diamine-thiocarbohydrazide-silver proteinate (HID-TCH-SP), low iron diamine (LID)-TCH-SP, and periodate (PA)-TCH-SP methods were used for the localization of sulfate, sulfate and carboxyl, and vicinal glycol- containing complex carbohydrates, respectively. Golgi vesicles and small precursor granules (0.2-0.4 micrometer in diameter) demonstrated strong HID-TCH-SP staining and labeled intensely after a 10-minute pulse with 35SO4(2). Crystalloid-free or immature specific granules (0.5-0.9 micrometers in diameter) labeled heavily after a 60-minute incubation and 60-minute chase with 35SO4(2). Immature granules were graded according to their HID-TCH-SP staining. Type I granules demonstrated strong rim staining and similar or somewhat less central staining, whereas type 2 granules only demonstrated rim staining, and type 3 granules lacked staining. Fully mature crystalloid-containing granules lacked staining. LID-TCH-SP similarly stained the HID-positive sulfated material in cytoplasmic granules. PA-TCH-SP stained some Golgi vesicles and diffusely stained all precursor granules and type 1 granules. Weaker staining was observed in type 2 granules and staining was very weak or absent in type 3 and crystalloid-containing granules. In early eosinophils, tubulovesicular structures (TVS) were observed rosetting and contacting precursor and type 1 granules. These TVS contained material with strong PA-TCH-SP staining but lacked HID-TCH-SP or LID-TCH-SP-reactive acidic glycoconjugates. Flattened Golgi saccules or early eosinophils stained weakly or not at all with the PA-TCH-SP method. Small granules and TVS in late (bilobed) eosinophils displayed PA-TCH-SP reactivity and lacked HID-TCH-SP staining but differed from TVS in early eosinophils in that they were not associated as rosettes with specific granules. These results indicate that sulfated and vicinal glycol-containing complex carbohydrates are differently disturbed in immature specific granules of eosinophils and presumably become masked to staining as the granule matures.

Animals↗
PubMedDate not supplied

In vivo myocardial gene transfer: optimization, evaluation and direct comparison of gene transfer vectors.

The purpose was to determine the relative efficiency, toxicity and duration of expression following gene delivery by intramyocardial injection of naked DNA, naked DNA complexed to cationic liposomes, naked DNA complexed to cationic liposomes with integrin-targetting peptide, recombinant (E1-/E3-) adenovirus, recombinant adeno-associated virus and recombinant (ICP27-) herpes simplex virus. All vectors incorporated a LacZ reporter driven by a promoter containing the hCMV-IE promoter/enhancer. Efficiency was scored by counting positive cells in five standard microscopic sections harvested from the left ventricular apex. Rabbit hearts (n = 100) were examined from 2 to 56 days after injection. Uncomplexed and complexed naked DNA were very inefficient with less than one positive cell visible per heart. The viral vectors all resulted in robust gene expression with adenovirus being the most efficient by at least one order of magnitude before 21 days. However, despite disparate titres, the efficiency beyond 21 days of adenovirus and adeno-associated virus were comparable. In contrast to adeno-associated virus, both adenovirus and herpes-simplex virus were associated with a marked inflammatory response. Despite reporter gene activity appearing only after 21 days, adeno-associated virus shows comparative promise as a myocardial gene delivery vector.

Adenoviridae↗
PubMedDate not supplied

Somatic gene therapy.

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Clinical Protocols↗