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Biomedical subjects

J Underwood

Publications and source records attributed to J Underwood.

At least 19 recordsLinked to original sources
PubMed1999

Allo-immunization elicits CD8+ T cell-derived chemokines, HIV suppressor factors and resistance to HIV infection in women.

We assessed the potential for an allogeneic-based vaccine against HIV infection in women who were allo-immunized with their partners' mononuclear leucocytes to prevent spontaneous recurrent abortion. Within 1 month of allo-immunization, there was significant upregulation in the concentrations of CD8 cell-derived suppressor factor activity, RANTES, and macrophage inflammatory proteins 1alpha and 1beta. Allo-immunization also downregulated the proportion of cells with CCR5 and CXCR4 receptors. We also found a dose-dependent decrease in HIV infectivity of CD4+ cells in vitro after allo-immunization with both primary and T-cell line adapted HIV-1. This study provides a rational basis for an alternative or complementary strategy of allo-immunization against HIV infection.

Abortion, Habitual↗
PubMed1999

Alzheimer's disease: correlation of the suppression of beta-amyloid peptide secretion from cultured cells with inhibition of the chymotrypsin-like activity of the proteasome.

Peptide aldehyde inhibitors of the chymotrypsin-like activity of the proteasome (CLIP) such as N-acetyl-Leu-Leu-Nle-H (or ALLN) have been shown previously to inhibit the secretion of beta-amyloid peptide (A beta) from cells. To evaluate more fully the role of the proteasome in this process, we have tested the effects on A beta formation of a much wider range of peptide-based inhibitors of CLIP than published previously. The inhibitors tested included several peptide boronates, some of which proved to be the most potent peptide-based inhibitors of beta-amyloid production reported so far. We found that the ability of the peptide aldehyde and boronate inhibitors to suppress A beta formation from cells correlated extremely well with their potency as CLIP inhibitors. Thus, we conclude that the proteasome may be involved either directly or indirectly in A beta formation.

Aldehydes↗
PubMed1999

Proteolytic fragments of Alzheimer's disease-associated presenilin 1 are present in synaptic organelles and growth cone membranes of rat brain.

Previous studies have demonstrated the molecular linkage of three causative genes for early-onset Alzheimer's disease: the presenilin 1 gene on chromosome 14, the presenilin 2 gene on chromosome 1, and the amyloid precursor protein gene on chromosome 21. In the present study, we have investigated the distributions of the approximately 20-kDa C-terminal and approximately 30-kDa N-terminal fragments of presenilin 1 and the amyloid precursor protein in rat brain and compared them with the distribution of several marker proteins. The fragments of presenilin 1 are present in synaptic plasma membranes, neurite growth cone membranes, and small synaptic vesicles of rat brain. Both proteolytic fragments are coenriched in the corresponding tissue fractions. Based on this observation, it seems likely that N- and C-terminal presenilin 1 fragments form a functional unit while remaining associated. In contrast to a predominant subcellular localization of presenilin 1 to the endoplasmic reticulum and Golgi apparatus in different cell lines, our results indicate that rat brain presenilin 1 fragments exit from these biosynthetic compartments to reach synaptic organelles in neurons.

Alzheimer Disease↗
PubMed1999

Mucosal inflammation in severe glucocorticoid-dependent asthma.

To improve our understanding of the inflammatory mechanisms underlying severe disease, a biopsy study was performed comparing 15 clinically unstable glucocorticoid-dependent asthmatics, 10 mild asthmatics, and 10 control subjects. Compared with mild asthma, severe asthma was characterized by reduced mucosal eosinophilia. Whilst no significant differences were found in the numbers of mast cells, neutrophils, CD3+ and CD4+ T-cells between the three groups, up to a 4-fold increase In the numbers of activated T-lymphocytes bearing the interleukin (IL)-2 receptor (IL-2R) was found in the mucosa in severe asthma compared to mild asthma (p = 0.03) and control subjects (p = 0.003). Compared to control subjects, the mucosa of severe asthmatics contained significantly (p = 0.02) higher numbers of IL-5+ cells, with no differences between mild and severe disease. In contrast, staining for the anti-IL-4 monoclonal antibody 3H4 revealed that biopsies from mild asthmatics contained more IL4+ cells than biopsies from severe asthmatics and control subjects (p = 0.0008). In the severe asthmatics, a close correlation (r(s) = 0.76, p = 0.005) was found between the numbers of IL-2R-bearing cells and the variability in peak expiratory flow. In conclusion, persistent T-cell activation is a prominent feature of severe asthma. These results also indicate that interleukin-5, and not interleukin-4, is upregulated in severe disease.

Administration, Topical↗
PubMed1999

Transferring public-health nursing research to health-system planning: assessing the relevance and accessibility of systematic reviews.

A descriptive study was designed to gain an understanding of the research needs, perceptions of barriers to research utilization, and attitudes towards systematic reviews of decision-makers in public health at the level of systems planning. Public-health consultants and managers in Ontario were surveyed about barriers to research utilization and awareness of and attitudes towards systematic reviews as a method of/vehicle for research transfer. Access to 5 completed reviews was provided in summary, abstract, and full form, and on diskette, hard copy, and Internet. A follow-up survey at 3 months assessed use, relevance, application, and further dissemination of the reviews. A total of 242 people in positions of public-health policy and decision-making participated. Respondents reported a great, largely unmet, need for research evidence. They viewed systematic reviews as likely to overcome the barriers to research use related to critical appraisal, time, timeliness, availability, cost and credibility, but not the barriers related to policy climate, authority, or implementation resources. Three months after requesting a review, 93% said they would follow it up; 91% remembered receiving it, and 71% of these had read it while 23% stated it played a part in program planning or decision-making.

Adult↗
PubMed1998

Surviving social assistance: 12-month prevalence of depression in sole-support parents receiving social assistance.

BACKGROUND: Although it is generally recognized that poverty and depression can coexist among single parents receiving social assistance, there is insufficient research on this topic. The goals of this study therefore were to investigate the prevalence, correlates and health care expenditures associated with depression among sole-support parents receiving social assistance. METHODS: Sole-support parents who had applied for social assistance in 2 regions of southwestern Ontario were included in the study. Depression was diagnosed with the 1994 University of Michigan Composite International Diagnostic Interview short forms. RESULTS: The 12-month prevalence rate of depressive disorder among the parents interviewed was 45.4% (345/760). A total of 247 (32.5%) had major depressive disorder alone, 19 (2.5%) had dysthymia, and 79 (10.4%) had both major depressive disorder and dysthymia ("double depression"). Those with major depressive disorder, particularly double depression, had significantly higher rates of coexisting psychiatric disorder than those without depressive disorders. Parents with depression reported higher rates of developmental delay and behaviour problems in their children than parents without depression. Expenditures for health care services were higher for parents with depression and for their children than for parents without depressive disorder and their children. INTERPRETATION: Single parents receiving social assistance have high rates of depression. Such parents with depression also have higher rates of other psychiatric disorders and higher expenditures for health care services, and their children have higher rates of developmental delay and behaviour problems.

Adaptation, Psychological↗
PubMed1997

Collection and normal levels of the amyloid precursor protein in plasma.

The amyloid precursor protein is contained in platelet alpha granules and released with degranulation. Methods are described to control for amyloid precursor protein release from platelets during blood collection and processing. In normal subjects (n = 97; age range, 44-84 years), the average plasma level of amyloid precursor protein was 6.5 +/- 1.8 ng/ml.

Adult↗
PubMed1997

Maternal response to paternal trophoblast antigens.

PROBLEM: What is the function of the immunoglobulin (Ig) G antibody bound to trophoblast in normal pregnancy, and what is the antigen? METHOD: IgG was acid eluted from term human placental microvesicles and reacted with the antigen, R80K, left on the vesicles. The eluted antibody was used to detect the antigen on monocytes, lymphocytes, and lymphoblastoid cell lines. The eluted antibody is highly polymorphic, but monoclonal antibodies (mAbs) were made against conserved regions of the molecule. These also reacted with the murine equivalent of the human R80K and were used in inhibition studies of natural killer (NK) cell killing and the mouse abortion models, CBA x DBA2 F1 resorption in CBA females, the endotoxin-induced resorption model, and a sonic stress-induced murine resorption model. RESULTS: All 600 syncytiotrophoblast microvesicle preparations of human term placenta had IgG antibody bound, elutable at pH 3.0. The eluted antibody reacted with about 15% of unrelated human placentae. In horses mares make detectable antibody early in pregnancy, at about the time of implantation. The IgG antibody was bound to an 80-kDa protein (R80K) also detected on B lymphocytes and monocytes. In HLA homozygous lymphoblastoid B cell lines, which reacted with one or more eluted antibodies, had a pattern of cytotoxicity independent of HLA Class I; and as a single 80-kDa peptide chain, R80K did not resemble HLA molecules. Genetic studies in horses show that of the two paternal allotypes of R80K detectable by placental alloantibodies, only one, usually the grandpaternal one, is present in all the placentae of a sibship. Two of 26 eluted human antibodies had affinity for K562 and inhibited killing by human peripheral blood NK cells. One mAb, BA11, against a conserved site on R80K inhibited killing of K562, and also reacted with the murine R80K homologue. BA11 inhibited murine NK cell killing and virtually completely inhibited three NK cell-dependent mouse resorption models. CONCLUSION: R80K protein is a target molecule for NK cell activity expressed on all placentae. It has a polymorphic alloantigenic determinant completely covered with maternal antibody in all successful term pregnancies. In murine NK cell-dependent models of abortion, a mAb against a monomorphic determinant present in human and murine R80K prevents abortion very effectively. It seems that the R80K molecule must be covered with antibody to prevent NK attacks on trophoblast.

Animals↗
PubMed1996

Identification of a novel cis-acting element participating in maximal induction of the human low density lipoprotein receptor gene transcription in response to low cellular cholesterol levels.

In this paper, we present both in vivo and in vitro evidence for the presence of a novel cis-acting regulatory element that is required for maximal induction of the human low density lipoprotein (LDL) receptor gene following depletion of cellular sterols in HepG2 cells. First, in vivo dimethyl sulfate footprinting of the human LDL receptor promoter before and after transcriptional induction in HepG2 cells revealed protection from -145 to -126, 5'-GAGCTTCACGGGTTAAAAAG-3' (referred to as FP1 site). Second, transient transfections of HepG2 cells with promoter luciferase reporter constructs containing the FP1 site resulted in significant enhancement (approximately 375%) of reporter gene expression in response to low levels of sterols compared with parallel plasmid without the FP1 site. In addition, this response was markedly attenuated on nucleotide substitutions within the FP1 site. Third, by electrophoretic mobility shift assays, the FP1 sequence was found to bind protein(s) from HepG2 nuclear extracts in a sequence-specific manner. In vitro binding of the FP1 mutants paralleled the results obtained for their in vivo transcription. On the basis of competition profiles, the FP1-binding factor is different from the known transcription factors binding to the AT-rich CArG and GArC motifs. Furthermore, the FP1-binding protein is not specific to HepG2 cells because nuclear factor(s) with the same specificity was observed in nuclear extracts of non-hepatic HeLa cells. We conclude that transcriptional induction of the LDL receptor gene in response to sterol depletion is mediated, in part, by an highly conserved novel cis-acting element through the binding of specific nuclear protein(s).

Base Sequence↗
PubMed1995

A subset of patients with recurrent spontaneous abortion is deficient in transforming growth factor beta-2-producing "suppressor cells" in uterine tissue near the placental attachment site.

PROBLEM: To determine if patients with unexplained recurrent miscarriage have a deficiency of decidual immunosuppressor cells that produce transforming growth factor beta type 2, as has been found in mice with abortion due to rejection and/or trophoblast failure. METHODS: Decidual biopsy specimens were taken as near to the placental attachment site as possible under ultrasound guidance from first trimester legal termination (control) patients with recurrent miscarriage and non-viable pregnancy, and from patients with sporadic missed abortion. The tissue was tested for TGF beta-2+ suppressor cells by in situ hybridization, immunohistochemistry, and analysis of supernatants. RESULTS: TGF beta-2-related suppressor molecules similar but not identical to those identified in pregnant mice were released by decidual lymphoid cells. Fifty percent of 14 recurrent miscarriage patients showed a lack of suppressor cells and 59% were subnormal in comparison to 20 controls and 5 sporadic miscarriage patients, where 80-85% of the patients had detectable suppressor cells. CONCLUSIONS: Suppressor cell deficiency is compatible with a role for rejection and/or trophoblast failure in some patients with recurrent miscarriage. Presence of suppressor cells in most patients with missed abortion (4/5) is compatible with an alternative cause of fetal death, similar to findings reported in genetic fetal death mice.

Abortion, Habitual↗
PubMed1994

Comprehensive T-cell epitope mapping of HIV-1 env antigens reveals many areas recognized by HIV-1-seropositive and by low-risk HIV-1-seronegative individuals.

Peripheral blood mononuclear cells from 12 asymptomatic human immunodeficiency virus (HIV)-1-seropositive and nine HIV-1-seronegative donors were screened for proliferative T-lymphocyte responses to peptides derived from a consensus sequence of the HIV-1 env gene products from 25 HIV-1 isolates. Two hundred seventy-eight overlapping 17mer peptides, incremented by three residues each, were pooled into groups, each containing eight sequential peptides, for use in proliferation tests. Thirty-eight additional peptides containing variant amino acid residues also were tested. Proliferation data were analyzed using an algorithm that reduced subjective bias and estimated the responding cell frequencies. Peripheral blood mononuclear cells from a majority of donors, regardless of HIV-1 status, recognized peptides within two pools derived from the gp120 sequence and peptides from one pool in gp41. Pool 25 peptides from gp41 (centered around residue 600 of the gp160 consensus sequence) were recognized most frequently. The observed inability to differentiate between responses of HIV-1-seropositive and HIV-1-seronegative individuals implies either a lack of HIV-1 disease-related immunodominant env epitopes or functional abrogation of HIV-1 env-specific T-helper lymphocyte responses soon after infection. The observed proliferation of T lymphocytes from noninfected, low-risk individuals questions the origin of the responses to HIV-1 env-derived peptides and suggest that preexisting, cross-reactive immunity could influence responses to HIV-1.

Adult↗
PubMed1994

Development of a temporary living skin replacement composed of human neonatal fibroblasts cultured in Biobrane, a synthetic dressing material.

BACKGROUND: Preferred coverings for excised burn wounds when sufficient autograft skin is not available are fresh or cryopreserved cadaveric skin. Problems with supply, preservation, immune rejection, and potential infection transmission accompanying the use of allograft skin underscore the need for effective alternative temporary skin replacements. METHODS: We cultured human neonatal fibroblasts (HF) for 4 to 6 weeks in nylon mesh of Biobrane, a synthetic dressing consisting of a thin layer of silicone bonded to nylon mesh. Secreted matrix proteins were identified by immunostaining and quantitated, and growth factor-specific messenger RNAs were identified by reverse transcription-polymerase chain reaction. Living grafts (Biobrane/HF) were sutured to full-thickness, excised wounds on athymic mice; control animals received Biobrane alone. Wounds were observed and biopsy specimens were obtained at intervals during the subsequent 40 days. RESULTS: After 3 to 6 weeks of culture in Biobrane the HF proliferated and secreted matrix proteins including type I collagen, fibronectin, and decorin, as well as messenger RNA for several growth factors (acidic fibroblast growth factor, basic fibroblast growth factor, and keratinocyte growth factor). Biobrane/HF grafts were transferred to full-thickness wounds, resulting in rapid fibrovascular ingrowth from the wound and effective wound closure for up to 40 days with minimal inflammatory responses. Biobrane control grafts adhered initially to wounds, but within several days many grafts developed subgraft exudates; histologic sections revealed marked inflammatory responses in these wounds. By 20 days, most BB grafts were separating from the underlying wounds that were closing by epithelialization and contraction. CONCLUSIONS: The Biobrane/HF living skin replacement provides long-term biologic coverage of full-thickness wound defects in mice with rapid incorporation of a living tissue matrix into the wound bed. Because HF have been found to be relatively nonantigenic when transferred to allogeneic hosts, Biobrane/HF grafts could replace the use of cadaveric allograft skin for achieving temporary wound closure after burn wound excision. Biobrane/HF grafts may persist on human wounds for weeks or months, with long-term persistence perhaps primarily dependent on durability of the silicone rubber layer.

Animals↗
PubMed1991

The relationship between the light scattering properties of zymogen granules and the release of their contained proteins.

The optical density of suspensions of the digestive enzyme-containing zymogen granule, a roughly spherical 1 micron diameter membrane-enclosed subcellular structure isolated from the exocrine pancreas of mammals, is reduced greatly when they are suspended in physiological media. This reduction in optical density is accompanied by the release of the granule's protein contents. It has traditionally been assumed that this property is due to granule lysis; that is, dissolution of the particle and its consequent disappearance as a strongly scattering object. Thus, lysis would decrease optical density by decreasing the number density of suspended spheres (N) according to Beer's law. However, as a general matter, changes in the optical density of suspensions of spheres may be a function of changes in the refractive index (m) or radius (r) of the objects as well. In this study, we apply Mie theory of scattering by small particles, which, in conjunction with Beer's law, allows us to evaluate whether changes in the scattering properties of granule suspensions are due to changes in N, m or r. Scattering by granule suspensions was reduced in three ways-pH, calcium ion concentration, and detergent concentration. A simple reduction in particle number did not account for decreased scattering and protein release in any of these circumstances. Instead, the changes appear attributable to decreases in particle size and refractive index.

Animals↗