Biomedical subjects
L Hudson
Publications and source records attributed to L Hudson.
Myelin-specific proteolipid protein is expressed in myelinating Schwann cells but is not incorporated into myelin sheaths.
Contrary to widely held beliefs, the gene encoding proteolipid protein (PLP), the major structural protein of central nervous system myelin, is expressed in Schwann cells and their tumors. Proteolipid mRNA was identified in human acoustic neuromas and in rat and rabbit sciatic nerves using a human PLP cDNA as a probe. Proteolipid protein itself was shown to be present in human and rat sciatic nerve Schwann cells by immunofluorescence microscopy and by Western blot analysis using antisera raised to a synthetic PLP polypeptide. Although easily detected in the Schwann cell body, PLP was not detected in the peripheral myelin itself, suggesting that the PLP is preferentially excluded from this portion of the Schwann cell membrane.
Comparison of inhaled albuterol powder and aerosol in asthma.
In this multicenter, randomized, double-blind study comparing the efficacy and safety of aerosolized albuterol with the dry powder formulation, 231 patients with chronic reversible obstructive airway disease were randomly allocated to receive either placebo albuterol aerosol followed immediately by active albuterol powder (200 micrograms) or active albuterol aerosol (two puffs, 180 micrograms) followed immediately by placebo lactose powder four times a day for a period of 12 weeks. No statistically significant differences were found between the powder and aerosol formulations with respect to pulmonary function, length of time mean FEV1 remained greater than or equal to 15% above baseline, physicians' assessments of patients' clinical response, or patients' subjective symptom scores. There were also no significant differences between treatment groups in cardiovascular effects, laboratory values, or adverse events. Among patients who expressed a preference for one of the delivery systems, half preferred using the powder. Results of this study demonstrate that 200 micrograms of albuterol powder is as safe and effective as 180 micrograms of albuterol aerosol.
Clinical Trypanosoma rangeli infection as a complication of Chagas' disease.
Laboratory studies on a group of 20 patients from the Rio Negro Valley, Colombia selected for detailed study showed that 14 gave antibody reactions on immunoassay consistent with Trypanosoma cruzi or T. rangeli infections. Four were diagnosed as having T. rangeli infection, 4 had mixed infections and 6 were infected with T. cruzi alone. Immunoprecipitation analysis showed that sera from T. cruzi-infected patients recognized a similar range of trypomastigote-derived polypeptides as sera from patients in Brazil, and all of the Colombian sera reacted with the 160 kiloDalton (kDa) polypeptide associated with active infection. Although sera from patients with T. rangeli infection alone gave a positive immunofluorescence or ELISA reaction with T. rangeli, they failed to bind to parasite polypeptides by either immunoprecipitation or Western blotting. Intriguingly, sera from patients with mixed infections consistently gave a stronger, but qualitatively similar, binding reaction in immunoprecipitation and Western blotting compared to sera from patients infected with T. cruzi alone.
Investigation of variation in phenotype and DNA content between single-conidium isolates of single Penicillium strains.
Variation in phenotypic properties was examined in three strains of closely related fasciculate species of Penicillium using 114 morphological, physiological, and biochemical characters. Thirty-six of these characters showed variation within single-conidium isolates of the same strain. Conidial sizes and nuclear DNA contents were compared using flow microfluorimetry; these results suggested that significant differences in conidial DNA content are associated with phenotypic variation. The taxonomic significance of the results is discussed.
Canine unilateral lung transplantation: effect of ciclosporin A on the frequency of donor-lytic lymphocytes.
Limiting dilution analysis showed that the frequency of precursor donor-lytic cytolytic lymphocytes increased dramatically within the leucocyte population recovered by broncho-alveolar lavage in dogs after unilateral lung transplantation. The increases for animals experiencing acute pulmonary rejection (11.5-24.8 times pre-operative level) and for those receiving long-term ciclosporin A therapy (5.4-17.6 times pre-operative level) were similar. Therefore, it appears that ciclosporin A does not prevent the sequestration of precursor donor-lytic cytotoxic cells within lung allograft tissue.
Use of monoclonal antibodies for the differential detection of Trypanosoma cruzi and T. rangeli in epidemiological studies and xenodiagnosis.
T. cruzi and T. rangeli have the same insect and mammalian hosts, including man, and in addition share approximately half the antigenic determinants recognised by the humoral response. Thus serodiagnosis of T. cruzi infection in areas where T. rangeli is endemic may include an unknown rate of false positives due to this antigenic cross-reactivity. Similarly, the results of xenodiagnostic procedures and epidemiological surveys of insect vectors are prone to distortion because of the close morphological resemblance of the epimastigote stages. The description of a T. cruzi epimastigote specific monoclonal antibody, 2A2, which reacts with both culture and insect derived epimastigotes provides a more reliable basis for differential diagnosis of these two parasites.
Analysis and isolation of leukaemic and residual normal B lymphocyte populations from patients with chronic lymphocytic leukaemia.
Two colour fluorescent staining using anti-Leu-1 and anti-B1 monoclonal antibodies has been combined with continuous flow microfluorimetry to analyse and isolate the T and B cell populations in B cell chronic lymphocytic leukaemia (B-CLL) patients. In Rai stage 0 patients two distinct B1 positive populations were detected and sorted; one was Leu-1- and the other Leu-1+. Analysis of the isolated populations showed that the former (Leu-1- B1+) represented the residual normal B cells, whereas the latter represented monoclonal CLL B cells. Short term culture of these cells in vitro showed that the Leu-1+ B1+ population secreted IgM, but not IgG, following PMA stimulation.
Direct effect of interleukin 2 on chronic lymphocytic leukaemia B cell functions and morphology.
The functional and morphological changes induced by recombinant interleukin 2 (IL-2) were studied in purified B cells from patients with untreated B chronic lymphocytic leukaemia (B-CLL). In eight of nine patients, purified B-CLL cells increased their DNA synthesis in response to IL-2 without preactivation in vitro. This response, studied in detail in three patients, was dose dependent and reached a maximum on day 5 or 6. IL-2 induced or increased IgM secretion in cultures from five of the nine patients studied. Two of this responsive group were particularly interesting as IL-2 not only stimulated IgM secretion but also induced the secretion of IgG. Immunoglobulin production was invariably monoclonal. B CLL cells incubated with IL-2 showed distinct morphological changes including an increase in the size of cytoplasm and enlargement of nuclei together with the appearance of nucleoli. These changes were present in all IL-2 treated cultures but were more pronounced in those containing immunoglobulin secreting cells. None of the IL-2 induced changes appeared to correlate with the clinical stage of the disease or the level of Tac antigen expression on the freshly isolated CLL B cells.
Expression of functional interleukin 2 receptors on chronic lymphocytic leukaemia B lymphocytes is modulated by recombinant interleukin 2.
In 16 of 18 chronic lymphocytic leukaemia (CLL) patients examined, a significant proportion of B cells in the leukaemic clone bound monoclonal antibodies specific for the interleukin 2 (IL-2) receptor site (CD25). B lymphocytes from patients tested showed a direct response to recombinant interleukin (rIL-2) during culture in vitro as shown by: (a) a ligand-mediated upregulation in the level of IL-2 receptor (IL-2R) expression (12 of 12 patients), (b) an increase in cell size (eight of nine patients), (c) an increase in 3H-thymidine uptake (four of six patients). Taken together, this evidence suggests that the majority of leukaemic B cells from all the CLL patients examined expressed functional IL-2 receptors in vitro. Intriguingly, maximal receptor upregulation or increase in cell size was achieved at a lower concentration (50 u/ml) of rIL-2 than was required to achieve maximal 3H-thymidine incorporation.
Neurofibrillary tangles from Alzheimer's disease brain purified using a cell sorter.
We have used a monoclonal antibody to label and purify neurofibrillary tangles using a cell sorter. The method should prove invaluable in future analyses of the biochemical makeup of neurofibrillary tangles, which in turn will greatly assist our comprehension of tangle pathology.
In vitro culture of Toxoplasma gondii in primary and established cell lines.
Explore the source record for details and available documents.
Immune precipitation and immunoblotting for the detection of Trypanosoma cruzi antigens.
The efficiency of immunoprecipitation and immunoblotting for detecting Trypanosoma cruzi antigens using rabbit and mouse antisera has been examined. Comparison of the starting material for each technique showed that the extraction methods resulted in a similar range of polypeptides when assessed by apparent Mr. Reaction with either hyperimmune rabbit sera or a sequential series of sera from infected mice, showed a significant disparity in the range of antigens revealed by each technique. Epitopes on polypeptides greater than 50 kDa were poorly preserved by immunoblotting compared to immunoprecipitation; however, below this threshold both techniques were equally efficient. Under the conditions of assay, it is probable that immunoprecipitation allows effective detection of both sequence and conformational determinants, whereas immunoblotting favours the detection of sequence determinants alone.
Recombination within the myelin basic protein gene created the dysmyelinating shiverer mouse mutation.
Shiverer (shi) is an autosomal recessive mutation in the mouse characterized by an almost total lack of central nervous system myelin. While small amounts of other myelin components are present in the brain of the shi mouse, the four forms of myelin basic protein (MBP) are not detectable. Previous investigations by us and others indicate that the MBP gene has undergone a major rearrangement in the shi mutant. Herein, we report in detail the nature and extent of the rearrangement: a 20-kilobase region within the MBP gene is missing in the mutant. We map the 5' breakpoint of the deletion to the second intron and the 3' breakpoint to a site 2 kilobases beyond the last MBP exon. The junction of the upstream and downstream portions of the gene contains only one nucleotide not accounted for by the wild-type MBP gene sequence. The 3' side of the deletion occurs in the 3rd of 11 tandem repeats of a 31-base-pair sequence. This region is rich in alternating purine and pyrimidine stretches, sequences that have been associated with both Z-DNA structures and gene rearrangements. The recombination junction shares several features with the junctions characterized by Anderson et al. [Anderson, R., Kato, S. & Camerini-Otero, D. (1984) Proc. Natl. Acad. Sci. USA 81, 206-210] in mouse L cells and is consistent with their model for a partially homologous recombination event. The structure of the shi recombination junction suggests that the donor DNA molecules were aligned in a partially homologous region before staggered cutting and joining occurred.
Emergence of three myelin proteins in oligodendrocytes cultured without neurons.
Oligodendrocytes, the myelin-forming cells of the central nervous system, were cultured from newborn rat brain and optic nerve to allow us to analyze whether two transmembranous myelin proteins, myelin-associated glycoprotein (MAG) and proteolipid protein (PLP), were expressed together with myelin basic protein (MBP) in defined medium with low serum and in the absence of neurons. Using double label immunofluorescence, we investigated when and where these three myelin proteins appeared in cells expressing galactocerebroside (GC), a specific marker for the oligodendrocyte membrane. We found that a proportion of oligodendrocytes derived from brain and optic nerve invariably express MBP, MAG, and PLP about a week after the emergence of GC, which occurs around birth. In brain-derived oligodendrocytes, MBP and MAG first emerge between the fifth and the seventh day after birth, followed by PLP 1 to 2 d later. All three proteins were confined to the cell body at that time, although an extensive network of GC positive processes had already developed. Each protein shows a specific cytoplasmic localization: diffuse for MBP, mostly perinuclear for MAG, and particulate for PLP. Interestingly, MAG, which may be involved in glial-axon interactions, is the first myelin protein detected in the processes at approximately 10 d after birth. MBP and PLP are only seen in these locations after 15 d. All GC-positive cells express the three myelin proteins by day 19. Simultaneously, numerous membrane and myelin whorls accumulate along the oligodendrocyte surface. The sequential emergence, cytoplasmic location, and peak of expression of these three myelin proteins in vitro follow a pattern similar to that described in vivo and, therefore, are independent of continuous neuronal influences. Such cultures provide a convenient system to study factors regulating expression of myelin proteins.
Antiviral activity of the photoactive thiophene alpha-terthienyl.
Explore the source record for details and available documents.
Immune suppression to Trypanosoma cruzi antigens is associated with infection but not immunisation.
Immune responses to Trypanosoma cruzi antigens in infected (C57BL/6 X C3H)F1 hybrid mice were followed throughout the acute infection and into the chronic phase, and compared to immune response kinetics of immunised, but uninfected, mice of the same strain. Anti T. cruzi antibody was detected by day 10 in infected animals and by day 5 in antigen sensitised mice. Animals sensitised with T. cruzi antigens showed strong delayed type hypersensitivity (DTH) responses to T. cruzi antigens. Infected animals were non-responsive during acute infection and immediately after resolution of parasitaemia, but showed similar responses to immunised animals during the chronic phase. The cell mediated immune response to T. cruzi antigens was assessed in vitro lymphocyte transformation tests. Antigen-sensitised mice were responsive to antigen at all time points. Infected animals showed reduced responses during acute infection but attained levels similar to antigen-sensitised mice around 60 days post infection. The results suggest immune suppression during the acute phase is related to infection, but that, unlike other trypanosome infections, suppressor cell-inducing antigens are not present in the T. cruzi antigen preparations tested.
Precursor frequency of donor-specific lymphocytes recovered from canine lung transplants.
Dogs receiving left unilateral allo- or auto-grafts were treated with Cyclosporin A (Cy A) for 4 days. Thereafter allografted transplant recipients showed pulmonary pathology consistent with rejection. Blood and bronchoalveolar lavage (BAL)-derived lymphocytes were isolated from the recipient animals before and at various times after operation and the frequency of allospecific precursor cytolytic lymphocytes (pCTL) determined by limiting dilution analysis (LDA). Samples from the autografted control animal did not show any post-operative frequency changes; however, both blood and BAL-derived lymphocytes from allografted recipients showed a significant post-operative increase in the proportion of donor-specific pCTL. This increase was consistently greater in samples from the transplanted than the autochthonous lung. The frequency of pCTL determined using targets from an unrelated dog showed no post-operative increase. It is likely that the increase in frequency of donor-specific pCTL recorded during graft-rejection is a specific consequence of an interaction between the graft and recipient's immune system.