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L Barnett

Publications and source records attributed to L Barnett.

At least 37 records · Page 2Linked to original sources
PubMed1997

Adult mice with targeted mutation of the interleukin-11 receptor (IL11Ra) display normal hematopoiesis.

Interleukin-11 (IL-11) is a pleiotropic growth factor with a prominent effect on megakaryopoiesis and thrombopoiesis. The receptor for IL-11 is a heterodimer of the signal transduction unit gp130 and a specific receptor component, the alpha-chain (IL-11R alpha). Two genes potentially encode the IL-11R alpha: the IL11Ra and IL11Ra2 genes. The IL11Ra gene is widely expressed in hematopoietic and other organs, whereas the IL11Ra2 gene is restricted to only some strains of mice and its expression is confined to testis, lymph node, and thymus. To investigate the essential actions mediated by the IL-11R alpha, we have generated mice with a null mutation of IL11Ra (IL11Ra-/-) by gene targeting. Analysis of IL11Ra expression by Northern blot and reverse transcriptase-polymerase chain reaction, as well as the absence of response of IL11Ra-/- bone marrow cells to IL-11 in hematopoietic assays, further confirmed the null mutation. Compensatory expression of the IL11Ra2 in bone marrow cells was not detected. IL11Ra-/- mice were healthy with normal numbers of peripheral blood white blood cells, hematocrit, and platelets. Bone marrow and spleen contained normal numbers of cells of all hematopoietic lineages, including megakaryocytes. Clonal cultures did not identify any perturbation of granulocyte-macrophage (GM), erythroid, or megakaryocyte progenitors. The number of day-12 colony-forming unit-spleen progenitors were similar in wild-type and IL11Ra-/- mice. The kinetics of recovery of peripheral blood white blood cells, platelets, and bone marrow GM progenitors after treatment with 5-flurouracil were the same in IL11Ra-/- and wild-type mice. Acute hemolytic stress was induced by phenylhydrazine and resulted in a 50% decrease in hematocrit. The recovery of hematocrit was comparable in IL11Ra-/ - and wild-type mice. These observations indicate that IL-11 receptor signalling is dispensable for adult hematopoiesis.

Animals↗
PubMed1997

Research bibliography: a union list of publications from Michigan's mineral springs, mineral wells, and mineral baths.

Although no more than a few dozen mineral wells and springs existed in Michigan at any one time, since their discovery over 125 years ago nearly two hundred firms have operated watering places for the suffering in this state. The publications produced by this industry were collectively quite numerous, but scarcely a hundred or so examples of this genre can be located today. On those rare occasions when materials of this nature can be found in out-of-print book stores or antiquarian dealers'catalogs, it is not uncommon for the asking price to approach $100 per piece. Now that this union list has revealed how scarce and valuable these publication are, persons and institutions possessing such items should take precautions to ensure the security of their holdings.

Baths↗
PubMed1996

Identification of pesticide poisoning in wildlife.

The Wildlife Incident Investigation Scheme investigates incidents of suspected poisoning of wildlife (also honey bees and companion animals) by pesticides in the United Kingdom. The approach to these investigations has evolved over the past 30 years. Field investigations, post-mortem examinations, toxicological data and experience of previous poisoning incidents assist in the selection and interpretation of appropriate chemical analyses. Several 'multi-residue' and several 'individual compound' analytical methods for pesticides in wildlife are currently in use; these are described.

Animals↗
PubMed1996

The validation of a 7-locus multiplex STR test for use in forensic casework. (I). Mixtures, ageing, degradation and species studies.

We have evaluated a multiplex STR system for routine forensic use, which co-amplifies six short tandem repeat (STR) loci; HUMTH01, D21S11, D18S51, D8S1179, HUMVWF31/A and HUMFIBRA (FGA), in conjunction with the X-Y homologous gene Amelogenin. Analysis of PCR products employs denaturing polyacrylamide gels coupled with fluorescent labelled primers and detection is undertaken on ABD 373A automated sequencers. The technique was shown to be robust and reproducible when samples were analysed under conditions consistent with those encountered in a forensic environment. The system was demonstrated to be human specific and is suitable for use with both aged and degraded material. Somatic stability was proven with a wide range of tissue types and we were able to detect mixtures at ratios between 1:10 and 10:1. During this study no incidence of sample mis-typing due to allelic or locus drop-out was observed. Furthermore, although additional artefact bands were occasionally encountered these did not interfere with the interpretation of results. The performance of the system with poor quality samples demonstrated its suitability as a powerful tool in forensic investigation.

Adult↗
PubMed1996

Polymerase chain reaction is highly predictive of relapse in patients following T cell-depleted allogeneic bone marrow transplantation for chronic myeloid leukemia.

In chronic myeloid leukemia (CML) the polymerase chain reaction (PCR) can be used to detect minimal residual disease after bone marrow transplantation (BMT). Previous studies have shown that PCR positivity is common following BMT. However, the clinical significance of this finding for any given individual who is PCR positive remains unclear, as many of these patients remain long-term disease-free survivors after allogeneic BMT. In the present study, we used PCR to detect BCR-ABL mRNA in 144 blood or marrow samples from 36 patients who received a T cell-depleted BMT for CML in first chronic phase. Six patients had no evidence of PCR-detectable residual disease at any time following transplant. The other 30 patients had at least one positive PCR result post-BMT. Once PCR positivity was found, it was usually sustained, with only four patients having a subsequent PCR negative assay. No patient who had two consecutive PCR-positive assays had a return to PCR negativity. None of the six patients with exclusively PCR-negative assays have developed either cytogenetic or hematologic relapse at a median follow-up of 42 months. Of the 30 patients with at least one PCR-positive assay post-BMT, 28 were PCR positive at last follow-up, and 22 have progressed to cytogenetic or hematologic relapse. If the PCR-positive assay occurred within 24 months of the transplant then the estimated probability of progression to cytogenetic or hematologic relapse was 65% at 24 months. Twenty of the 26 patients who were studied early (< or = 6 months) after BMT had at least one positive PCR assay. Fifteen of the 20 patients who were PCR positive < or = 6 months following transplant have progressed to either cytogenetic or hematologic relapse resulting in an estimated probability of relapse of 84% at 24 months. These results indicate that following T cell-depleted BMT for CML in first chronic phase, PCR is highly predictive of relapse and may identify a cohort of patients in need of therapeutic intervention before the onset of overt clinical relapse.

Biomarkers, Tumor↗
PubMed1994

Minimal residual disease is more common in patients who have mixed T-cell chimerism after bone marrow transplantation for chronic myelogenous leukemia.

Determining both lymphoid chimerism and the presence of minimal residual disease after allogeneic bone marrow transplantation (BMT) for chronic myelogenous leukemia (CML) could be helpful to the understanding of the biology of leukemic relapse in this disease. We prospectively investigated 32 patients with CML post-BMT by assessing T-cell chimerism and minimal residual disease using sensitive polymerase chain reaction (PCR) methodologies. Patients were studied between 1 and 24 months post-BMT. Thirty patients received a T-cell-depleted marrow grafts and 2 received unmanipulated marrow. All but 1 patient were conditioned with total body irradiation (TBI)+thiotepa+cyclophosphamide (Cy). The other patient received TBI+Cy as conditioning. The T cells were exclusively of donor origin in 12 of 16 patients who were tested at 1 month post-BMT, but were mixed chimeric in 11 of these patients by > or = 3 months. Once mixed T-cell chimerism was documented, no patient returned to having all donor T-cells. At a median follow-up of 12 months, minimal residual disease was present in 18 of 22 patients with mixed T-cell chimerism and in 3 of 10 patients with full donor chimerism. The actuarial molecular relapse rate at 24 months for the two groups is 91% and 33%, respectively (P < .02). The finding of BCR-ABL mRNA within the first 6 months of transplant or on two consecutive assays was highly predictive of subsequent cytogenetic or hematologic relapse (P = .032 and P < .02, respectively). Ten patients, 9 with mixed T-cell chimerism, have relapsed (4 clinical, 6 cytogenetic) at a median of 12 months post-BMT. These data suggest that mixed T-cell chimerism may be a marker for abrogation of graft-versus-leukemia activity that is thought to be pivotal in eradicating minimal residual disease after BMT for CML.

Bone Marrow Transplantation↗
PubMed1994

Alteration of cell cycle kinetics and immunoglobulin gene transcription as the result of multiple agonist stimulation of murine B cells.

Several laboratories have established that anti-IgM can inhibit polyclonal B cell activation by LPS or LPS/DxS. The use of intact anti-IgM results in an inhibition of both proliferation and differentiation, whereas F(ab')2 fragments inhibit only differentiation. Since signal transduction by both alpha-Ig's (intact and F(ab')2 fragments) is known to be mediated by PIP2 hydrolysis, we have investigated the effects of A23187 and PMA on LPS/DxS activation of splenic B cells. These agents mimic the second messengers generated as the results of PIP2 hydrolysis. As with intact alpha-IgM, either agent in conjunction with LPS/DxS resulted in an inhibition of proliferation as assessed by [3H]thymidine uptake. However, when proliferation was assessed by acridine orange (AO) staining and flow cytometric analysis, cells were observed to have entered cell cycle. This disparity between AO staining and proliferation was resolved by using BrDu/Hoechst quenching analysis and revealed a delay in cell cycle transit time as the result of multiple agent stimulation. Since both anti-IgM's result in the inhibition of differentiation, we also investigated the effects of these agents on differentiation normally observed with LPS/DxS alone activation of B cells. A23187 and PMA, either alone or in combination, were observed to result in a decrease in mRNA-encoding mu immunoglobulin of the 2.4-kb mRNA for secreted IgM.

Animals↗
PubMed1994

Clinicians as caregivers: role of attachment organization in treatment.

The relationship between case managers' attachment organization and interventions used with clients who have serious psychopathological disorders was examined. Adult Attachment Interviews were administered to 27 clients and their 18 case managers. Interviews were coded by means of Kobak's Q-set, which yields scores for secure-insecure and preoccupied-dismissing attachment strategies. Case managers were interviewed during each of 5 months regarding their most recent interventions; interventions were coded for depth of intervention and attention to dependency needs. Compared with secure case managers, insecure case managers attended more to dependency needs and intervened in greater depth with preoccupied clients than they did with dismissing clients. Case managers who were more preoccupied intervened with their clients in greater depth than did case managers who were more dismissing.

Adult↗
PubMed1993

Vectors lambda 200g and lambda 200c: two useful derivatives of lambda 2001.

We describe the construction and uses of two new phage lambda replacement vectors. Both are modifications of lambda 2001 which allows selection of cloned inserts by the Spi- phenotype, following the replacement of a gam+ filler fragment. Vector lambda 200g has a second gam gene with an amber mutation in its right arm which enables the selection of clones with inserts in the normal way in Su0 host bacteria and the maintenance of their genetic stability by subsequent growth in Su+ strains. Vector lambda 200c is designed for complementation studies. It contains a cat gene and the attP site of lambda. Recombinants can be inserted into the bacterial chromosome or into an episome with the aid of appropriate helpers.

Attachment Sites, Microbiological↗
PubMed1993

Allograft rejection after penetrating keratoplasty for keratoconus.

We retrospectively studied 91 penetrating keratoplasties in 65 patients to evaluate the overall incidence of allograft rejection and the incidence in unilateral as compared with bilateral cases following penetrating keratoplasty for keratoconus. All surgeries were performed by the senior author following a standardized technique. The average age of the patients was 35 years; the average follow up, 6.5 years. Nine of the 91 grafts (9.9%) were rejected. The time of rejection varied from 6 months to 13 years after surgery. Eight of the nine rejections (88.9%) were reversible with steroid treatment and have survived up to 10 years. One graft failure requiring repeat penetrating keratoplasty (1.1%) occurred 13.25 years after surgery. The unrejected clear grafts have survived up to 21.5 years. The results of this study support the excellent prognosis of penetrating keratoplasty for keratoconus.

Adolescent↗
PubMed1992

Myeloid and lymphoid chimerism after T-cell-depleted bone marrow transplantation: evaluation of conditioning regimens using the polymerase chain reaction to amplify human minisatellite regions of genomic DNA.

Determining both myeloid and lymphoid chimerism after T-cell-depleted allogeneic bone marrow transplantation (BMT) could be helpful in the understanding of the biology of engraftment and could provide a rational method of assessing the ability of different conditioning regimens to promote engraftment. We prospectively investigated the role of different pretransplant conditioning regimens in 29 leukemic patients post-BMT by assessing myeloid and T-cell chimerism using a rapid and sensitive polymerase chain reaction (PCR) method. Minisatellites are hypervariable regions of DNA consisting of tandem repeats of a core nucleotide sequence, and allelic polymorphism results from differences in the number of the repeats. We used this variation to distinguish between donor and recipient cells post-BMT. Seventeen patients (9 sibling and 8 unrelated donors) received conditioning with hyperfractionated total body irradiation (TBI), thiotepa, and cyclophosphamide (Cy). Of the other 12 patients (all sibling donors), 11 received TBI plus Cy plus another agent: VP16, carboplatinum, or AZQ. One patient received TBI plus thiotepa plus VP16. All but one of the patients studied received marrow from HLA-identical donors. PCR analysis confirmed donor lymphoid engraftment within 8 days of transplant in six of six patients studied. All granulocyte DNA was of donor origin within the first 4 weeks of transplant, regardless of the conditioning regimen. The day +28 T cells were exclusively of donor origin in 14 of 17 patients who received TBI plus thiotepa plus Cy, but were mixed chimeric in 10 of 12 patients who received other conditioning regimens (P < .001). Early graft rejection was seen in one unrelated transplant recipient conditioned with TBI plus thiotepa plus Cy. Late graft failure was observed in 3 of 12 patients with mixed T-cell chimerism and in none of 16 patients with full donor chimerism at day +28. However, 5 of 16 patients who had complete T-cell chimerism at day +28 developed acute graft-versus-host disease (GVHD), whereas no patient with mixed chimerism had acute GVHD. Our results indicate that minisatellite PCR is a rapid and sensitive method for assessing chimerism post-BMT, that the donor T cells are important for consistent durable engraftment, and that TBI plus thiotepa plus Cy may be superior to the other regimens studied in inducing full donor chimerism. Larger numbers and longer follow-up are necessary to confirm these data and also to assess the relationship between complete donor T-cell chimerism and leukemia-free survival.

Adolescent↗
PubMed1992

Use of grafts smaller than the opening for keratoconic myopia and astigmatism. A prospective study.

A prospective study was conducted on 15 consecutive keratoconic eyes to evaluate the use of grafts smaller than the opening in keratoconic myopia and astigmatism. All surgeries were performed by the senior author. Average age of the patients was 41.1 years. Average follow-up was 1.6 years. After all sutures were removed, results showed an average decrease in myopia of 13.24 diopters (D) (range 1.75 to 23.25) principally from corneal flattening and a small reduction in axial length. Average postoperative spherical equivalent was -2.17 D (range +1.50 to -7.25). The average postoperative astigmatism was 3.78 D (range 1.75 to 6.00). This study and a previous retrospective study suggest that the use of grafts 0.25 mm smaller than the opening, i.e., 7.50/7.75 mm, for penetrating keratoplasty in keratoconus is justified.

Adult↗