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Biomedical subjects

P Martin

Publications and source records attributed to P Martin.

At least 811 records · Page 45Linked to original sources
PubMed1986

Dynamic interaction between brief vagal stimulation and heart period on atrial contractility.

We have characterized the dynamic interaction of the simultaneous changes of vagal activity and heart period on atrial contractile force. Our hypothesis was that the linear sum of these two separate effects was not equal to the response of the unpaced heart when both effects were elicited simultaneously. We performed 3 experiments: we measured the beat-to-beat inotropic response to brief vagal stimuli when the heart was paced; this represented the pure vagal effect on contractile force. We measured the responses to identical stimuli when the heart was not paced; this represented the effect of the combined influences. Finally, we measured the contractile responses to the identical sequences of changing cardiac intervals that were recorded in part 2 above but in the absence of vagal activity; this represented the pure effect of changes in cardiac cycle length on contractile force. These experiments were done at 3 levels of vagal stimulus intensity. We first subtracted the responses of the paced from those of the unpaced heart. These derived differences represented the linear elimination of the pure vagal effect from the combined responses. We then compared these differences with the responses to changing cardiac intervals that were measured in the absence of vagal activity (part 3, above). These two sets of responses were not significantly different at the low level of stimulus intensity. For the mid level of stimulus intensity, they were significantly different for only the 3rd and 4th beats after the stimulus. For the high level of stimulus intensity, they were significantly different for each of the first through the 4th beats (only) after the stimulus. We conclude that the independent effects of vagal activity and changing heart period combine non-linearly to produce the resultant inotropic response when the intensity of brief vagal stimuli is increased, but we cannot draw this conclusion at the lower levels of stimulus intensity.

Animals↗
PubMed1986

Validation of questionnaire information on risk factors and disease outcomes in a prospective cohort study of women.

To assess the validity of self-reported illnesses, medical records were reviewed for participants reporting major illnesses on the biennial follow-up questionnaires used in a prospective cohort study which began in 1976. In over 90% of cases of cancer of the breast, skin, large bowel, and thyroid, histopathology reports confirmed the subjects' self-report. Lower levels of confirmation were obtained for cancers of the lung, ovary, and uterus. Application of strict diagnostic criteria also gave lower levels of confirmation for myocardial infarction (68%) and stroke (66%). Among random samples of women reporting fractures and hypertension all records obtained confirmed self-reports. For self-reported elevated cholesterol levels 85.7% of self-reports were confirmed. Self-report is a valuable epidemiologic tool but may require additional documentation when the disease is diagnostically complex.

Adult↗
PubMed1986

Haematological reassessment of rheumatoid arthritis using an automated method.

Thirteen haematological parameters were measured in 44 patients with rheumatoid arthritis (RA) and 39 disease control patients with ankylosing spondylitis (AS). Using a 10 000 cells per sample automated differential counter the most frequent abnormalities found were monocytopenia, low numbers of large unstained cells, basophilia and increased numbers of cells with high peroxidase activity (HPX). The total white cell count, lymphocyte and monocyte counts, the HPX count, platelet distribution width and erythrocyte sedimentation rate were able to distinguish RA from AS at a statistically significant level. Discriminant function analysis showed that a maximum of 55% of RA patients could be correctly classified into disease state when combinations of six out of seven laboratory tests were used.

Arthritis, Rheumatoid↗
PubMed1986

Characterization of a myc-containing retrovirus generated by propagation of an MH2 viral subgenomic RNA.

We have previously isolated, from wild-type MH2 virus that contains the two oncogenes mil and myc, mutants defective in one or the other oncogene product. We report here the molecular cloning and extensive characterization of MH2 CL25 provirus lacking the v-mil oncogene. Our results indicate that this virus corresponds to the propagation of the 2.8-kilobase subgenomic RNA of MH21.

Base Sequence↗
PubMed1986

Attenuation of the responses to repeated cholinergic interventions in the isolated dog atrium.

In the isolated, blood-perfused canine right atrium, which was pretreated with propranolol, negative chronotropic and inotropic responses were evoked by stimulation of the intramural parasympathetic nerve fibers or by intra-arterial infusion of acetylcholine (ACh). Successive cholinergic interventions were applied; first, a conditioning intervention for 2 min was given, then this was followed by a test intervention for 4 min. The two interventions were separated by a rest period that varied from 15 to 240 s. The cardiac responses to the conditioning parasympathetic nerve stimulation quickly reached maximum levels, and then they "faded" or progressively diminished back toward the control level. The inotropic responses to the conditioning infusion of ACh (1 microgram/min) faded slightly but the chronotropic response did not. After the rest period, the test nerve stimulation evoked responses that also gradually faded with time. The maximal amplitude of the responses to the test stimuli were less than those to the conditioning stimuli. This reduction in the maximal amplitude of the cardiac responses to the test stimuli was more pronounced with high frequency stimulation (30 Hz) than with low frequency stimulation (5 Hz). The decrement was also more pronounced the shorter the rest period, and it was greater at earlier times after beginning the stimulation. Conversely, the maximal cardiac responses to test infusions of ACh were not appreciably less than the responses to the conditioning infusions. We conclude, therefore, that the diminution of the cardiac responses to the second test stimulation of the parasympathetic nerve fibers was mainly ascribable to a prejunctional rather than to a postjunctional mechanism.

Acetylcholine↗
PubMed1986

Antibody response to pretreatment immunization and post-treatment boosting with bacterial polysaccharide vaccines in patients with Hodgkin's disease.

Overwhelming sepsis is a serious complication of staging splenectomy in Hodgkin's disease. To define an optimal immunization strategy, 51 patients received 14-valent pneumococcal, Haemophilus influenzae type b, and meningococcal group C vaccines before therapy and 2 to 12 months after completion of therapy. Natural antibody levels to bacterial polysaccharide antigens and the response to immunization were normal or only minimally impaired in patients with Hodgkin's disease compared with findings in healthy adults. The antibody response was not affected by the timing of immunization relative to splenectomy but was frequently impaired if chemotherapy was begun less than 10 days after immunization. Both post-immunization and "natural" antibody declines were significantly greater in patients with Hodgkin's disease than in healthy adults; the magnitude of the decline was related to the intensity of therapy. A spontaneous rebound in antibody concentrations was not seen during the 12 months after treatment. Booster immunizations of all three vaccines given during this period also failed to elicit an antibody increase.

Adolescent↗
PubMed1986

[Preparation and characterization of specific antisera directed against different polypeptide domains encoded by the c-myc oncogene for studying the expression of this gene introduced into quail or rat cells].

By using bacterial expression vectors, we have prepared antisera directed against two polypeptidic domains encoded by exons 2 and 3 of the human c-myc oncogene. These antisera which detect specifically the human c-myc proteins allow us to analyse the expression of human c-myc gene activated by retroviral sequences and introduced in quail embryo cells (QEC) or in established rat embryo fibroblastic cell line (208 F). Although human myc mRNA are expressed in the two cell types, the p64/p67 human c-myc proteins are only detected in the QEC.

Animals↗
PubMed1986

Leu-1+ (CD5+) B cells. A major lymphoid subpopulation in human fetal spleen: phenotypic and functional studies.

Examination of the cell surface phenotype of fetal splenic lymphocytes demonstrated a major, novel subpopulation of B cells that co-express Leu-1 (CD5) in addition to B cell differentiation antigens (Leu-1+ B cells). These cells are similar to some conventional B cells in that they express HLA-DR, Leu-12, and B1, as well as both immunoglobulin (Ig) M and IgD. They comprise 40 to 60% of total splenic B cells in the fetus but are infrequent in fetal liver and adult spleen. Fetal Leu-1+ B cells do not respond to pokeweed mitogen with either proliferation or Ig secretion, and in contrast to the murine counterpart, Ly-1 B cells, they do not constitutively produce Ig. Leu-1+ B cells were incapable of augmenting Ig production of Leu-1- B cells when suboptimal numbers of T cells were present; however, they did require the presence of T cells to secrete antibody. They do not cap either the CD5 protein or surface Ig. These cells are a unique subpopulation of fetal splenic B cells that do not function as conventional B cells. Their role in the humoral immune response is unknown. They may represent the normal stage of B cell development, which is reflected in the phenotype of B cell CLL cells.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1986

Detection of clonal excess in lymphoproliferative disease by kappa/lambda analysis: correlation with immunoglobulin gene DNA rearrangement.

Previous studies have suggested that analysis of the distribution of surface immunoglobulin light chain isotypes by flow cytometry provides evidence for monoclonality of B cell tumors and may detect populations of circulating tumor cells in patients with lymphoproliferative disease. We have used simultaneous flow cytometry and DNA restriction enzyme analysis on 58 samples of tissue and blood to determine whether lymphocyte populations detected by "kappa/lambda" analysis are indeed monoclonal. In greater than 90% of cases, abnormalities detected by flow cytometry correlated with monoclonal rearrangements of immunoglobulin genes as detected by Southern blot analysis. By analyzing tissue and blood from the same patients, we have also demonstrated that monoclonal circulating cells detected by flow cytometry reflect peripheral circulating tumor cells, since DNA from these cells shows the same immunoglobulin rearrangement as DNA from the original tumors in these patients. Although mixing studies suggested that DNA rearrangement studies were more sensitive than was flow cytometry in detecting minor populations of monoclonal lymphocytes, we found only one case in which this affected the diagnostic accuracy of the kappa/lambda analysis, with one notable exception, that of detection of a monoclonal proliferation of B cells that did not express surface immunoglobulin. The kappa/lambda test thus offers a powerful diagnostic tool in the evaluation of lymphoproliferative disease.

DNA↗
PubMed1986

[Early radiologic signs of Burkitt's lymphoma].

This paper relates a case of Burkitt lymphoma, whose initial presentation was a deep-bite malformation, that accentuated within a month. Orthodontic consultation referred this 8 years old boy to hospital, where diagnosis was ascertained. The authors discuss radiographs that have been taken before and during the installation of the clinical symptomatology. They point out the main radiographic signs encountered with maxilla involvement in Burkitt lymphoma.

Burkitt Lymphoma↗
PubMed1986

Elimination of Daudi lymphoblasts from human bone marrow using avidin-biotin immunoadsorption.

Biotinylated antibodies and an avidin-Sepharose 6MB column were utilized in a novel approach to deplete selected cell populations from human bone marrow. Fluorescein-labeled Daudi lymphoblasts were mixed with bone marrow mononuclear cells in a model system, and removal of Daudi cells was quantitatively assessed with an inverted fluorescent microscope. Treatment using the biotinylated monoclonal antibody 2H7 reactive with Bp32 antigen (expressed on Daudi cells) followed by passage over avidin-Sepharose produced greater than two logs of Daudi cell removal from bone marrow. An alternative method was tested by treating cells successively with nonbiotinylated monoclonal antibody and biotinylated goat antimouse immunoglobulin followed by passage over avidin-Sepharose. Up to three logs of Daudi cells could be eliminated from bone marrow with quantitative recovery of hematopoietic progenitors. The use of biotinylated goat antimouse immunoglobulin eliminates the need to prepare a biotin conjugate of each individual monoclonal antibody. The clinical application of cellular immunoadsorption using the avidin-biotin system may prove useful in bone marrow transplantation.

Antibodies, Anti-Idiotypic↗
PubMed1986

Hyperacute graft-v-host disease in patients not given immunosuppression after allogeneic marrow transplantation.

Sixteen patients with leukemia in relapse or second to third remission, 5 to 27 years old (median, 17), were given cyclophosphamide (60 mg/kg X 2) and total body irradiation (2.25 Gy for each of seven days) followed by unmodified marrow grafts from HLA-identical siblings. Patients did not receive posttransplant immunosuppression and were followed a median of nine months (range, 5-17). Prompt engraftment was sustained in 12 patients with a median time of 16 days (range, 10 to 63) to achieve 500 neutrophils/mm3. One patient failed to engraft, one had delayed engraftment, and two had late poor graft function. All 15 with engraftment developed moderate to life-threatening graft-v-host disease (GVHD, eight grade II and seven grade III-IV). This syndrome was hyperacute (median onset eight days [range, 7 to 29] posttransplant) and manifest by severe skin disease (14 patients at stage 3 and one at stage 4), fever (ten patients), and liver (four patients, stage 3-4) or gut (four patients, stage 3-4) involvement. Serial tissue biopsies confirmed acute GVHD in 13 of 15 patients. Ten were treated with antithymocyte globulin and cyclosporine (four survive), and four with corticosteroids (two survive). Actuarial survival to 17 months was 37%. Causes of death included interstitial pneumonia (four), infection (three), graft failure (one), venocclusive disease (one), and relapse of leukemia (one). Age-matched controls receiving standard methotrexate after transplant had comparable relapse-free survival but only a 25% incidence of grade II-IV acute GVHD (P less than .0001). We conclude that deleting posttransplant immunosuppression is associated with frequent and severe hyperacute GVHD, infectious complications, and occasional poor graft function.

Acute Disease↗
PubMed1986

[Dental amalgams and allergy].

After a short description of the fundamental basis of allergy, particularly in relation to contact allergy, the authors review the 41 published cases of allergy to dental amalgam consisting of 30 female and 11 male patients. 20 of these patients recovered on removal of the dental amalgam. The most frequent symptoms were of the remote cutaneous type (38/41 cases) while local symptoms, particularly gingivitis and stomatitis, occurred in 17 cases. These probably underestimate the true prevalence of the condition for several reported cases have not been published. The authors then go on to describe the sensitizing property of amalgam in relation to the occupational environment and the length of time that the amalgam has been in the mouth. Mercury is the most common sensitizing agent, but other metals, particularly cooper, zinc or silver could also be implicated. The authors attempted to explain the physio-pathological mechanism of sensitization via the cutaneous as well as the oral, digestive and respiratory tracts by describing the chelating properties of metals with cellular or tissue constituents. In the last chapter, the prevention and clinical treatment of sensitization to dental amalgams is described.

Adolescent↗
PubMed1986

[Erosion of polyethylene cupulae. Radiological study of 123 Charnley total prostheses].

The authors have measured the distance between the centre of the femoral component and that of the acetabular component using a ten times magnification radiograph. This technique allows greater precision in the radiological assessment. 123 total hip prostheses were measured after an average follow-up of 131 months. The mean annual wear was 1.1 mm. There was a regular progression throughout the period. These results were comparable with those obtained by other authors. The wear appears to be only half as significant as in prostheses with a 32 mm femoral component (Muller type). The wear was maximal in young male patients. Patients who were overweight did not have any increased incidence of wear.

Acetabulum↗