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Biomedical subjects

P M Johnson

Publications and source records attributed to P M Johnson.

At least 19 recordsLinked to original sources
PubMed1992

Monoclonal antiphospholipid antibody reactivity against human placental trophoblast.

Naturally occurring antibodies against the negatively charged phospholipids cardiolipin (CL) and phosphatidylserine (PS) have been associated with recurrent pregnancy loss. One prevalent hypothesis proposes that antiphospholipid antibody (aPL) mediated pathophysiology is through increased placental thrombosis. In this study we investigated the reactivity of three mouse monoclonal aPLs with term and 26 week human placental preparations. Each monoclonal antibody reacted differently with CL and PS; 3SB9b reacted with PS (CL-/PS+), D11A4 reacted with CL (CL+/PS-) and BA3B5C4 reacted with both CL and PS (CL+/PS+). 3SB9b reacted strongly with the syncytiotrophoblastic layer of both formalin fixed and frozen placental tissue. Sporadic reactivity was observed against the cytotrophoblastic layer. BA3B5C4 reacted strongly and specifically with cytotrophoblastic cells. D11A4 had only weak reactivity in the subtrophoblastic stromal region of the placenta in frozen sections. aPL staining was also observed against extravillous cytotrophoblast. BA3B5C4 stained cytoplasmic structures, whereas 3SB9b stained the plasma membrane region with little cytoplasmic staining. These data suggest that the trophoblastic layer is reactive with aPLs and may potentially be directly damaged through mechanisms unrelated to thrombosis. In addition, the trophoblastic layer directly in contact with the maternal circulation is most reactive with aPLs that are PS+ rather than CL+. The differential reactivity of 3SB9b and BA3B5C4 suggests that the antigenic conformation involving PS on the cytotrophoblast is altered concurrent with fusion into the syncytium.

Antibodies, Monoclonal↗
PubMed1992

Germ cell alkaline phosphatase in human seminal plasma following vasectomy.

Germ cell alkaline phosphatase (also termed placental-like alkaline phosphatase or Nagao isoenzyme) was assayed in seminal plasma using monoclonal antibody-based enzyme immunoassays in samples obtained both before and after vasectomy. In all cases, germ cell alkaline phosphatase fell to undetectable levels within 14 days of operation. A fall in seminal plasma germ cell alkaline phosphatase may thus be an early indication of successful vasectomy.

Alkaline Phosphatase↗
PubMed1992

Dental hygiene practice: international profile and future directions.

Results of an international survey on dental hygiene are reported. The survey was conducted in 1988 through the International Dental Hygienists' Federation as part of a project to establish and maintain an international database on the profession. Information was collected by mail from national dental hygienist associations, using a 40-item questionnaire developed for the purpose; preliminary tabulations were validated by the associations. Information is presented for 13 countries-Australia, Canada, Denmark, Italy, Japan, Korea, The Netherlands, Nigeria, Norway, Sweden, Switzerland, the United States and the United Kingdom. Characteristics include historical development, numbers and distribution, education, regulation, scope of practice, employment settings and conditions, professional organisation, and perceived oral health and professional issues. The profiles and issues are examined in the light of broader socio-economic, demographic, epidemiological, technological and policy-related trends and changes. Implications for future health and organisational planning are noted.

Australia↗
PubMed1992

Expression of the CD46 antigen, and absence of class I MHC antigen, on the human oocyte and preimplantation blastocyst.

Expression of CD46 and class I major histocompatibility complex (MHC) antigens by human oocytes and 6-8-day unhatched expanded preimplantation blastocysts has been studied by immunocytochemistry. The CD46 antigen, a cell surface complement regulatory protein, was expressed by unfertilized oocytes as well as strongly by both the inner cell mass and trophectoderm of preimplantation blastocysts. In contrast, class I MHC antigens were not usually expressed by either oocytes or blastocysts. These data support the concept that gametes and embryonic cells involved in fertilization and early implantation events, respectively, may be protected from immunological recognition or attack both by the lack of class I MHC antigens and by expression of the CD46 complement regulatory protein.

Antibodies, Monoclonal↗
PubMed1991

Polymorphism of the human CD46 gene in normal individuals and in recurrent spontaneous abortion.

Restriction fragment length polymorphism analysis of the human CD46 gene, which encodes a cell surface complement regulatory protein, has been performed using a 1.5-kb cDNA probe containing a complete CD46 coding sequence. The sum of the invariant band sizes indicates that this gene encompasses at least 35-kb genomic DNA. Polymorphisms were detected in normal individuals with both HindIII and EcoRI. Several of the polymorphic bands occurred significantly less frequently in recurrent spontaneous abortion individuals. Northern blot analysis has shown the predominant RNA transcript size to be 4.2 kb in trophoblast-derived cell lines and peripheral blood mononuclear cells, indicating these transcripts may contain an unusually long 3'-untranslated region.

Abortion, Habitual↗
PubMed1991

Evaluation of an ingestible telemetric temperature sensor for deep hyperthermia applications.

We have investigated the potential of an ingestible thermometric system (ITS) for use with a deep heating system. The ingestible sensor contains a temperature-sensitive quartz crystal oscillator. The telemetered signal is inductively coupled by a radiofrequency coil system to an external receiver. The sensors, covered with a protective silicon coating, are 10 mm in diameter and 20 mm long and are energized by an internal silver-oxide battery. Experimental studies were carried out to investigate the accuracy of the system and the extent of reliable operation of these sensors in an electromagnetic environment. Different measurements were repeated for five sensors. Calibration accuracy was verified by comparison with a Bowman probe in the temperature range 30 degrees C to 55 degrees C. Linear regression analysis of individual pill readings indicated a correlation within +/- 0.4 degrees C at 95% prediction intervals in the clinical temperature range of 35 degrees C to 50 degrees C. Further work is required to improve this accuracy to meet the quality assurance guidelines of +/- 0.2 degrees C suggested by the Hyperthermia Physics Center. Response times were determined by the exponential fit of heat-up and cool-down curves for each pill. All curves had correlation coefficients greater than 0.98. Time (mean +/- SE) to achieve 90% response during heat-up was 115 +/- sec. Time to cool-down to 10% of initial temperature was 114 +/- 4 sec. The effect of the external antenna and sensor spacing and the angle of orientation of the sensor relative to the antenna plane were also studied. Electromagnetic interference effects were studied by placing the sensor with a Bowman probe in a cylindrical saline phantom for the tests in an annular phase array applicator. Different power levels at three frequencies--80, 100, and 120 MHz--were used. Accurate temperature readings could not be obtained when the electromagnetic power was on because of interference effects with the receiver. However, the temperatures read with the ITS immediately after the electromagnetic power was switched off correlated well with the Bowman probe readings across the power categories and the three frequencies used. The phantom was heated to steady state, with a Bowman probe placed at the central axis of the cylinder used as control. During the heat-up period and the steady state, the mean difference (+/- SE) between the ITS and Bowman probe was 0.12 degrees C (+/- 0.05 degrees C).(ABSTRACT TRUNCATED AT 400 WORDS)

Electromagnetic Fields↗
PubMed1991

The occurrence and significance of hand deformities in early rheumatoid arthritis.

One hundred rheumatoid arthritis patients (38 men, 62 women), with mean age of 53 years and mean disease duration of 11.5 months, were followed. Standardized clinical, biochemical, and radiographic evaluation was performed regularly. After 2 years the prevalence of ulnar deviation, buttonhole deformity, and swan neck deformity was 13%, 16%, and 8%, respectively. Altogether, 31 patients had developed one or more deformities. There was no difference in age or gender distribution and no predominance of the dominant hand. Each patient with a deformity was matched according to age, sex, and disease duration with another early RA patient without deformity. The deformity group had more active disease, less grip strength, more disability, and markedly more severe radiographic changes. When studied retrospectively at a time point 3 months prior to the detection of deformity, synovitis of relevant joints was as common in the group who developed deformities as in the control group. This suggests that joint inflammation may contribute to the genesis of deformity but additional factors are needed. Hand deformities were found to be common in early RA.

Adult↗
PubMed1991

Evaluation of sequential plasma and urinary tumor necrosis factor alpha levels in renal allograft recipients.

The macrophage cytokine tumor necrosis factor-alpha is released early in immune activation and may be detected in the peripheral circulation. This study has investigated the occurrence of plasma and urinary TNF in 30 renal allograft recipients. Although circulating TNF may be detected in 20% of pretransplant or normal control samples, levels were significantly elevated during 65% of allograft rejection episodes. Plasma TNF levels did not rise in graft failure due to acute tubular necrosis, but were always highly raised in systemic infection. In contrast, urinary TNF was only detected in association with acute rejection (49%) or tubular necrosis (14%), and no controls had detectable urinary TNF. These findings indicate that evaluation of circulating and excreted TNF may give further insight into the immunobiology of graft rejection.

Communicable Diseases↗
PubMed1991

Feeding the terminally ill: dietitians' attitudes and beliefs.

Medical, legal, and bioethical discussions have focused on withholding or withdrawing nourishment from adults who are terminally ill or in persistent vegetative states, yet few discussions have considered the dietitian's role. In June 1990, the Supreme Court upheld an individual's right to refuse life-prolonging procedures, provided those wishes had been clearly documented. This decision, and The American Dietetic Association's 1987 guidelines for feeding the terminally ill, may enable dietitians to evaluate complicated situations regarding feeding and nonfeeding of patients. A survey sent to 590 registered dietitians in The American Dietetic Association's Nutrition Support dietetic practice group resulted in a 42% (n = 250) response rate. In general, dietitians were more willing to discontinue total parenteral nutrition than to discontinue enteral, noninvasive enteral, or oral feedings. They thought that feeding could be discontinued if it causes pain or worsens the condition, if death is imminent, or if the patient has requested that feeding be stopped. University courses and continuing education programs on the ethics and legalities of feeding terminally or critically ill adults will enable dietitians to take active roles in the decision-making process and to promote awareness of relevant issues with patients and families.

Analysis of Variance↗
PubMed1990

Growth factor-induced release of a glycosyl-phosphatidylinositol (GPI)-linked protein from the HEp-2 human carcinoma cell line.

The release of a GPI-linked oncofetal protein (PLAP) from HEp-2 cells has been studied as an indicator of endogenous PI-specific PLC activation. A non-hydrolysable GTP analogue, EGF and insulin all produced a dose-dependent release of PLAP from these cells. This indicates that an increase in PLC activity following either growth factor binding or G protein activation may cause cellular release of PLAP.

Alkaline Phosphatase↗
PubMed1990

Northern blot analysis of HLA-G expression by BeWo human choriocarcinoma cells.

The BeWo human choriocarcinoma cell line expresses an unusual 41 kDa beta 2-microglobulin-associated class I MHC antigen. HLA-E, -F and -G are known to encode antigens of lower Mr than HLA-A, -B or -C proteins. Using locus-specific probes, we now show that RNA isolated from BeWo cells contains markedly more HLA-G transcripts than peripheral blood lymphocytes (PBL), whilst the converse was noted for HLA-B. These results support recent cloning and sequencing data showing the presence of HLA-G transcripts in BeWo cells.

Blotting, Northern↗
PubMed1990

Estimation of serum V kappa IIIb light chains in rheumatoid arthritis and correlation with CD5-positive B-cells.

The presence of V kappa IIIb light chains in the sera of rheumatoid arthritis (RA) patients has been evaluated by an enzyme-linked immunosorbent assay (ELISA). V kappa IIIb light chains have been confirmed to be largely restricted to IgM, and were rarely detected in the IgG fraction of sera. The concentration of total serum V kappa IIIb did not significantly vary with age, nor did it correlate with IgM-rheumatoid factor (RF) titre. Although total serum V kappa IIIb was not significantly increased in RA patients compared with matched controls, IgM-RFs frequently contained V kappa IIIb. Using flow cytometry, CD5-positive B-cells were not increased in these RA patients compared with healthy laboratory control personnel. Furthermore, there was no direct correlation between total serum IgM V kappa IIIb content and CD5-positive B-cell numbers in peripheral blood.

Adult↗
PubMed1990

Serum antibodies reactive with Saccharomyces cerevisiae in inflammatory bowel disease: is IgA antibody a marker for Crohn's disease?

Sera from patients with Crohn's disease (CD) and ulcerative colitis (UC) have been evaluated for antibodies reactive with Saccharomyces cerevisiae (anti-Sacc antibodies) using an enzyme-linked immunoassay (ELISA). IgG anti-Sacc antibodies were detected in 63% (25/40) of CD patients, compared with 15% (4/27) of UC patients (p less than 0.001) and 8% (5/60) healthy adult controls (p less than 0.001). Furthermore, the prevalence of detectable IgG anti-Sacc antibodies in adult patients with coeliac disease, dermatitis herpetiformis, irritable bowel syndrome or atopic eczema was not significantly different to controls. In comparison, the prevalence of detectable IgG anti-Escherichia coli antibodies was not significantly different between CD (75%) or UC (79%) patients. More particularly, elevated levels of serum IgA anti-Sacc antibodies were detected in 17/40 CD patients, but in none of the 27 UC patients. These data confirm that serum antibodies reactive with S. cerevisiae are strongly associated with CD and further show that serum IgA anti-Sacc antibodies may be specific for this disorder.

Adolescent↗
PubMed1990

Immunology of human placental trophoblast membrane antigens.

The identification of the mechanisms of immunological survival of the semiallogeneic conceptus in utero during viviparous pregnancy is central to current studies in pregnancy immunology, since any other unmatched intrauterine allograft would be expected to suffer tissue rejection. Elucidation of normal feto-maternal interactions in human uteroplacental tissues, as well as the characterization of fetal trophoblast cell surface antigen expression, has now offered insight into these processes; these have largely focussed on the lack of trophoblastic expression of classical class I MHC antigens and the specialized local immuno-regulatory response that may occur following maternal recognition of other particular trophoblast cell surface antigens. The role of trophoblastic expression of growth factor receptors, endogenous retroviral activity and cellular oncogene products in the growth and differentiation of trophoblast, and its interaction with the host maternal tissues in early pregnancy, remains to be further clarified.

Antigens, Surface↗