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Biomedical subjects

J Oliver

Publications and source records attributed to J Oliver.

At least 109 records · Page 6Linked to original sources
PubMed1994

[The clinical and echocardiographic factors predictive of bioprosthetic leaflet rupture. The clinical tolerance for prosthetic malfunction].

OBJECTIVE: The objective of this research was to determine the existence of predictors of bioprosthetic valve disruption depending on the echocardiographic characteristic of the biologic prosthesis. It also determines the factors that provoke a need of emergency surgery and a bad clinical tolerance to the prosthetic dysfunction. METHODS: Clinical and echocardiographic features of two groups of 28 and 21 patients, all of them carrying bioprosthesis, were compared. The groups were homogeneous in sex, age, location and durability of the prosthesis. The first group showed leaflet disruption in a period of 6 months to 1 year after the study, not in the second group. Calcification, thickness and mobility of leaflets, prosthetic function were studied. An echocardiographic score was given between 4 and 10 points. Left ventricular function and pulmonary pressure were also studied. RESULTS: Valve thickness was statistically different in both groups (95% of the first group vs 71.3% of the second, p = 0.0281). There was no significant difference in calcification (52% vs 38.7%), nor in leaflet mobility (71.5% normal in the first group vs the 80% of the second group), nor in the prosthetic function (52.3% vs 76.6%, respectively). It was not found in the echocardiographic score either. Left ventricular function and pulmonary pressure were 91.6% and 55% normal respectively in the first group. They were 80% and 45.83% normal in the second group. Clinical onset of disruption was: 5 asymptomatic patients, 2 patients noticed a change in prosthetic click, 14 cases with progressive dyspnea, 6 patients with acute pulmonary edema and 1 patient with cardiopulmonary arrest and effective resuscitation. Symptoms were kept under control with medical treatment in 22 patients (78.55%) and 6 patients were referred to surgery. These latter suffered from pulmonary hypertension and two of them had left ventricular dysfunction. Surgical mortality was 3% (1 patient). CONCLUSIONS: No echocardiographic features were found as being predictors of imminent bioprosthetic disruption. However, leaflet thickness is the most common finding. Symptoms of disruption in patients without high surgical risk factors (left ventricular dysfunction or pulmonary hypertension) are kept under control with medical treatment. Therefore, "prophylactic" surgery is not needed in bioprosthesis with signs of degeneration and normal hemodynamic performance.

Adolescent↗
PubMed1994

ANP binding sites are increased in choroid plexus of SLS-1 rats after 9 days of spaceflight.

Specific alpha-rat 28-amino acid atrial natriuretic peptide [ANP(99-126)] (rANP) binding sites in choroid plexus and meningia of rats flown for 9 days on the mission STS-40 (SLS-1) carried on the space shuttle Columbia in June 1991 were analyzed after incubation of brain sections with 125I-rANP and autoradiography, using computer-assisted microdensitometric image analysis. The number of 125I-rANP binding sites (expressed by Bmax values) in the choroid plexus of lateral and third ventricles of these rats was significantly increased (x 1.5-2.5 times), as compared with that found in ground control rats. No differences in the binding affinity (deducible from Kd values) were observed at the level of these structures. The choroid plexus from the fourth ventricle of the same rats displayed no changes in the binding capacity or affinity after the spaceflight. Meningia from the rats flown in space did not demonstrate any significant modifications of the number of 125I-rANP binding sites, but displayed a significant increase in Kd values, which suggested a reduced affinity of the meningeal ANP receptors during a 9-d spaceflight. The possibility that atrial natriuretic peptide may be involved in the regulation of fluid and electrolyte fluxes in the brain, during adaptation to microgravity, through modified expression of specific high affinity receptors, mainly in choroid plexus from forebrain or in meningia, must be considered.

Animals↗
PubMed1993

Downregulation of the antigen presenting cell function(s) of pulmonary dendritic cells in vivo by resident alveolar macrophages.

Class II major histocompatibility complex (Ia)-bearing dendritic cells (DC) from airway epithelium and lung parenchyma express low-moderate antigen presenting cell (APC) activity when freshly isolated. However, this function is markedly upregulated during overnight culture in a manner analogous to epidermal Langerhans cells. The in vitro "maturation" process is inhibited by coculture with pulmonary alveolar macrophages (PAM) across a semipermeable membrane, and the degree of inhibition achieved can be markedly increased by the presence of tumor necrosis factor alpha. In addition, PAM-mediated suppression of DC function is abrogated via inhibition of the nitric oxide synthetase pathway. Functional maturation of the DC is accompanied by increased expression of surface Ia, which is also inhibited in the presence of PAM. Prior elimination of PAM from DC donors via intratracheal administration of the cytotoxic drug dichloromethylene diphosphonate in liposomes, 24-72 h before lung DC preparation, achieves a comparable upregulation of APC activity, suggesting that (consistent with the in vitro data) the resident PAM population actively suppresses the APC function of lung DC in situ. In support of the feasibility of such a regulatory mechanism, electron microscopic examination of normal lung fixed by intravascular perfusion in the inflated state (which optimally preserves PAM in situ), revealed that the majority are preferentially localized in recesses at the alveolar septal junctions. In this position, the PAM are in intimate association with the alveolar epithelial surface, and are effectively separated by as little as 0.2 microns from underlying interstitial spaces which contain the peripheral lung DC population. A similar juxtaposition of airway intraepithelial DC is demonstrated with underlying submucosal tissue macrophages, where the separation between the two cell populations is effectively the width of the basal lamina.

Animals↗
PubMed1993

Effects of angiotensin II receptor blockade on remnant glomerular permselectivity.

This study examined the mechanisms by which angiotensin II (Ang II) receptor blockade improves glomerular barrier function in rats with reduced nephron number. Proteinuria was measured at four weeks after 5/6 renal ablation, and rats were then divided into a group which received the Ang II receptor blocker MK954 and a group which received no treatment. Studies performed one week later showed that Ang II receptor blockade reduced proteinuria without altering GFR in renal ablated rats. Micropuncture studies showed that Ang II blockade reduced both mean arterial pressure (142 +/- 7 mm Hg, ablation without treatment; 105 +/- 2 mm Hg, ablation with treatment) and glomerular transcapillary pressure (54 +/- 3 mm Hg, ablation without treatment; 43 +/- 1 mm Hg, ablation with treatment). Dextran sieving studies showed that untreated rats developed a size-selective defect characterized by increased transglomerular passage of neutral dextrans with radii 54 to 76 A and a charge-selective defect characterized by an increased transglomerular passage of anionic dextran sulfate with a radius of approximately 18 A. Ang II blockade reduced fractional clearance values for large neutral dextrans near to values observed in normal rats but had no effect on the fractional clearance of dextran sulfate (0.68 +/- 0.11, ablation without treatment; 0.66 +/- 0.08, ablation with treatment; 0.46 +/- 0.05, normal rats). These findings indicate that reducing Ang II activity improves size-selectivity without affecting charge-selectivity in injured remnant glomeruli.

Angiotensin II↗
PubMed1993

Localized pleural microdeposition of type A amyloid in a patient with rheumatoid pleuritis. Histologic distinction from pleural involvement in systemic amyloidosis.

Decorticated pleural tissue from a 74-year-old man with rheumatoid arthritis, an exudative pleural effusion, and normal left ventricular function contained microscopic deposits of amyloid A protein, localized to the interface between a deep layer of dense fibrocollagen and a layer of granulation tissue beneath a surface fibrin exudate. Previously reported instances of pleural amyloid deposition have occurred in patients with presumed systemic amyloidosis, and most such effusions are the result of congestive heart failure. This patient had no evidence of systemic amyloidosis, and this case appeared to be an example of an unusual form of localized amyloidosis, so-called periinflammatory amyloidosis A. These observations suggest that amyloid in a pleural biopsy should not be construed per se to be diagnostic of systemic amyloidosis.

Aged↗
PubMed1993

Changes in social support and quality of life: a case study of a man with an enduring psychotic illness.

The Government's White Paper on community care has drawn attention to the importance of assessing changes in a person's well-being which occur as a consequence of clinical and social interventions. In the UK the evaluation of the quality of life of people with chronic mental illness is relatively new. This case study demonstrates the use of the 'Lancashire Quality of Life Profile' in routine clinical practice with reference to residential changes in the 'care programme' of a person with a long history of a severely disabling psychotic illness. The formulation and review of his care plan were determined by a network of agencies involved in his long term care.

Activities of Daily Living↗
PubMed1993

Mental health policy in practice: lessons from the All Wales Strategy Mental Illness.

The ultimate objective of the All Wales Strategy--Mental Illness, is to produce a community based mental health service led by multidisciplinary community mental health teams. This paper is based upon a report commissioned by the Welsh Office Social Services Inspectorate based upon a review of progress in the implementation of the strategy through scrutiny of County Joint Plans and meetings with County Joint Planning Teams. In general, we found that community multidisciplinary teamwork was not well developed throughout Wales. Insufficient attention was being paid to issues of staff development and the capacity to monitor and evaluate service developments. The need for a baseline assessment of current performance by health and social services authorities seemed inescapable, if the impact of the strategy is to be reliably and validly assessed.

Adult↗
PubMed1993

[Monocytoid lymphoma evolving into large-cell lymphoma].

Monocytoid B cell lymphoma (MBCL) is a newly recognized low-grade lymphoma. The malignant cells of MBCL seems to be the counterpart of reactive monocytoid B cells. The MBCL cells show a resemblance to the cells of hairy cell leukemia (HCL). The cell of MBCL exhibits immunoglobulin light chain restriction and markers of terminal BG cell differentiation. On the other hand, the HCL lack expression of CD 25 and are tartrate resistant, acid phosphatase-negative. The MBCL has prediction for elderly females. At the time of diagnosis, it is usually present in stage I or II. It may be difficult to differentiate the clinical and morphological expression of MBCL from that of any other indolent lymphoproliferative diseases, especially HCL and small lymphocytic lymphoma. Unlike other low grade lymphomas in MBCL, however, splenomegaly and bone marrow involvement are uncommon, while leukemic conversion is very rare. The MBCL transformation or association to high grade lymphomas is very unusual. In this case, it isn't clear if MBCL undergoes progression to higher grade lymphomas or if there is a "composite lymphoma" at the onset, in any case the prognosis is worse. In our patient, the involvement seemed to be only at the spleen and caeliac nodes, there was not bone marrow involvement. The fast evolution suggests that the MBCL underwent a transformation to a higher grade lymphoma. It is a common behavior in the low grade lymphoma.

Aged↗
PubMed1992

The molecular defect in a family with mild atypical osteogenesis imperfecta and extreme joint hypermobility: exon skipping caused by an 11-bp deletion from an intron in one COL1A2 allele.

We have investigated a family with an autosomal dominantly inherited connective-tissue defect causing extreme joint hypermobility, premature osteoporosis and late-onset fractures. Analysis of collagenous proteins from affected individuals showed a deletion in some alpha 2(I) chains. Peptide mapping localized this to the CB peptide alpha 2CB4, which covers the N-terminal one-third of the protein chain. Polymerase chain reaction amplification and sequencing of cDNA derived from this region of the mRNA identified a heterozygous deletion of the 54 bp comprising exon 9. Similar analysis of the genomic DNA revealed an 11-bp deletion from bp3 to bp13 of IVS-9. This disrupts the consensus 5' splice signal (GTAAGT) and leads to exon skipping. In a family study of 13 affected and unaffected family members using both heteroduplex formation and direct analysis for the deletion, all of the affected, but no unaffected individuals, were found to carry the deletion. This generated a positive Lod score of 2.6 with the Liped programme.

Alleles↗
PubMed1992

Studies on the surface phenotype and functions of dendritic cells in parenchymal lung tissue of the rat.

Immunohistochemical analysis of frozen sections of rat lung tissue identified a widely distributed population of highly pleiomorphic Ia+ cells in alveolar septal walls, which are negative for the pan-macrophage marker ED4 and the related markers ED1, ED2 and ED9. Semi-purified dendritic cells (DC) prepared from lungs of rats exposed to an aerosol of ovalbumin (OA) triggered modest levels of proliferation of OA-immune T cells in vitro, demonstrating the potential of these cells in surveillance for inhaled antigens in vivo. Lung wall also exhibited modest stimulatory activity in mixed lymphocyte/leucocyte reaction (MLR) assays. Overnight incubation of the DC in T-cell culture supernatant markedly increased their T-cell stimulatory properties, concomitant with increased expression of Ia. These results suggest that analogous to epidermal Langerhans' cells, lung wall DC can effectively bind inhaled antigens in situ, but require additional maturation/activation signals before they can efficiently present the antigen to T cells.

Animals↗
PubMed1991

Preliminary investigation of crystals of the neutral lipase from Pseudomonas fluorescens.

The neutral lipase from the bacteria Pseudomonas fluorescens, marketed under the trade name LpL-200S, has been crystallized in a form suitable for X-ray diffraction analysis from 35% n-propanol at pH 8.5. The crystals are monoclinic prisms and are of space group C2 with a = 91.00 A, b = 47.17 A, c = 35.21 A and beta = 121.43 degrees. There is one molecule of the protein as the asymmetric unit of the crystals. The diffraction pattern extends to at least 1.6 A resolution and the crystals are extremely robust in terms of X-ray exposure.

Crystallization↗
PubMed1991

Preparation of representative homogenates of biological tissues: effect of salt on protein extraction.

A technique for the preparation of representative homogenates of tissues is described. For most soft tissues and biological fluids (liver, kidney, semen) more than 80% of protein was recovered after homogenization in isotonic buffer. With tissues that are harder to homogenize, such as heart, spleen, and skeletal muscle, however, only approximately 40-50% of protein was extracted in this medium. Inclusion of salt or salt plus detergent during the homogenization increased recovery of the protein to levels close to those recorded with soft tissues. The increase represented a true recovery and was not an artifact induced by salt/detergent. This situation is parallel to previously reported results for lipid-rich biological tissues.

Animals↗
PubMed1991

Studies on the density, distribution, and surface phenotype of intraepithelial class II major histocompatibility complex antigen (Ia)-bearing dendritic cells (DC) in the conducting airways.

Conventional immunohistochemical analysis of airway intraepithelial class II major histocompatibility complex (Ia) expression demonstrates a morphologically heterogeneous pattern of staining, suggestive of the presence of a mixed population of endogenous antigen presenting cells. Employing a novel tissue sectioning technique in conjunction with optimal surface antigen fixation, we now demonstrate that virtually all intraepithelial Ia staining throughout the respiratory tree in the normal rat, can be accounted for by a network of cells with classical dendritic cell (DC) morphology. The density of DC varies from 600-800 per mm2 epithelial surface in the large airways, to 75 per mm2 in the epithelium of the small airways of the peripheral lung. All the airway DC costain for CD4, with low-moderate expression of a variety of other leukocyte surface markers. Both chronic (eosinophilic) inflammation and acute (neutrophilic) inflammation, caused respectively by inhalation of chemical irritants in dust or aerosolised bacterial lipopolysaccharide (LPS), are shown to be accompanied by increased intraepithelial DC density in the large airways (in the order of 50%) and up to threefold increased expression of activation markers, including the beta chain of CD11/18. The kinetics of the changes in the DC network in response to LPS mirrored those of the transient neutrophil influx, suggesting that airway intraepithelial DC constitute a dynamic population which is rapidly upregulated in response to local inflammation. These findings have important theoretical implications for research on T cell activation in the context of allergic and infectious diseases in the respiratory tract.

Animals↗
PubMed1991

Structure of human glutathione S-transferase class Mu genes.

Nucleotide sequencing of a human cosmid clone shows that the exon-intron structures of a glutathione S-transferase multigene family are conserved between man and rat, that the human gene family is clustered and that gene conversion events have occurred within the cluster. In addition, between man and rat, there is a high degree of nucleotide sequence identity not only in exons but also in some introns. These conserved sequences are coincident with homologous sequences subject to gene conversion in both species, and hence the utilization of gene conversion by this gene family has itself been conserved. By using transient-expression assay the conserved/converted regions are shown to be capable of modulating transcriptional activity. The data suggest that DNA repair by gene conversion may be a chemical immunity mechanism. which could result in acquired resistance to toxins and, in particular, drug resistance due to glutathione S-transferase in tumours.

Amino Acid Sequence↗
PubMed1991

The mechanisms of action of lithium. I. Effects on serotoninergic and noradrenergic systems in normal subjects.

The effects of 2 weeks of lithium carbonate administration at therapeutic plasma levels were examined in 11 normal volunteers. Serotoninergic function before and after lithium administration was assessed using low-dose intravenous clomipramine hydrochloride challenge, while urinary and plasma metabolites of norepinephrine (NE) were used to assess noradrenergic systems. Long-term lithium administration in normal subjects did not significantly or consistently enhance serotonin-mediated neuroendocrine responses but did increase measures related to neuronal release of NE. No statistically significant effects of lithium on prolactin, corticotropin, or cortisol responses to serotoninergic challenge could be detected. The probability of a type II error was assessed, and a doubling of prolactin level was unlikely to have been missed, although more modest increases (less than 75%) could have been overlooked. After 2 weeks of lithium administration, there were significant increases in 24-hour urinary excretion of NE, normetanephrine, and fractional NE release, compatible with increased neuronal release of NE and a lithium-induced subsensitivity in alpha 2-adrenergic receptor function. These changes were not statistically significant after 1 week of administration, suggesting that increased NE release is characteristic of long- rather than short-term lithium administration. Since previous reports have demonstrated enhanced prolactin responses after short- but not long-term lithium use, the present study points to temporal specificity in lithium's effects on both serotoninergic and noradrenergic function. Lithium's effects on NE release were consistent but small (a 16% increase), while its effects on serotoninergic responses were larger (a 50% increase in prolactin responses) but quite inconsistent, suggesting that neither of these systems is the primary site of action of lithium.

Adrenocorticotropic Hormone↗
PubMed1991

Acute myocardial infarction after blunt chest trauma in young people: need for prompt intervention.

We describe four cases of acute myocardial infarction in young patients, secondary to blunt chest trauma. One case was treated with intracoronary thrombolysis and angioplasty, two cases received systemic thrombolysis, and the last one did not have any reperfusion therapy. The coronary angiograms of the left anterior descending artery showed thrombosis in two cases, coronary dissection in one case, and no morphological lesions in the other. We encourage the early performance of angiographic studies in these patients, adjusting the therapy to their pathophysiologic mechanism.

Accidents, Traffic↗
PubMed1991

Regulation of immune response to inhaled antigen by alveolar macrophages: differential effects of in vivo alveolar macrophage elimination on the induction of tolerance vs. immunity.

A single intratracheal instillation of liposomes containing dichloro methylene diphosphonate into rats eliminated greater than 80% of the alveolar macrophage (AM phi) population, and the population was not significantly renewed during the ensuing week. AM phi depletion markedly increased local antibody production in the lung wall in pre-primed animals exposed to antigen aerosols. However, AM phi depletion did not affect the normal development of protective tolerance (particularly in the IgE antibody class) to inhaled antigen in immunologically naive rats. These results are discussed in relation to regional control of immune responses in the upper vs. the lower respiratory tract.

Aerosols↗