PubMed Health⌕ Search

Biomedical subjects

A Whyte

Publications and source records attributed to A Whyte.

At least 73 records · Page 4Linked to original sources
PubMed1991

Changes in IgG glycoform levels are associated with remission of arthritis during pregnancy.

It was found that the percentage of IgG-associated agalactosyl N-linked oligosaccharides (G0) falls during normal human pregnancy and rises to values higher than before conception following delivery (n = 10, 39-55 days after delivery). Serial bleeds from a normal pregnant woman showed a fall in the percentage G0 during gestation and a rapid rise post-partum. A similar study on a pregnant arthritic woman with a pathologically elevated percentage G0 also showed a fall in percentage G0 during pregnancy and a rapid rise post-partum. The changes in IgG glycosylation in the pregnant arthritic woman occurred simultaneously with the pregnancy-induced remission and post-partum recurrence of disease. A further seven pregnant women with rheumatoid arthritis were studied and analysis of their G0 values pre- and post-partum confirmed the result. In a further series of experiments using an animal model of rheumatoid arthritis, DBA/1 mice with collagen-induced arthritis were found to have elevated G0 levels compared with control mice. The percentage G0 was found to fall simultaneously with pregnancy-induced remission to the same value as non-arthritic pregnant mice. Post-partum recurrence of arthritis in these mice was also accompanied by a simultaneous and rapid rise in percentage G0. Pseudopregnancy did not result in a change in the percentage G0, confirming the effect of true pregnancy. Since the proportion of agalactosyl IgG is abnormally high in the serum of patients with rheumatoid arthritis these changes in IgG glycoform levels, or the factors which control them, may be related to the mechanisms underlying remission of arthritis in humans during pregnancy.

Acetylglucosamine↗
PubMed1991

Maintained pregnancy levels of oestrogen afford complete protection from post-partum exacerbation of collagen-induced arthritis.

Pregnancy is known to influence the course of rheumatoid arthritis (RA) in women, as well as type II collagen-induced arthritis (CIA) in DBA/1 mice. A characteristic feature is the remission during gestation and the exacerbation of the diseases during the post-partum period. In the case of CIA in DBA 1 mice, two hormonal changes have been assumed to be critical for the induction of the post-partum flare: (i) the fall in steroid hormone levels from those present during pregnancy; and (ii) surges of prolactin (PRL) release at and after delivery. Our results show that treatment with oestradiol during a short period immediately after parturition protects the mouse from a post-partum flare of the disease, and that treatment with bromocriptine, a drug known to inhibit the endogenous PRL release, has a significant though less marked effect. Studies of lactating (i.e. animals with physiological stimulation of endogenous PRL release) and non-lactating arthritic mice revealed no clear-cut differences, indicating that PRL is of minor importance for the induction of the post-partum flare. Some steroids other than oestradiol, which may be implicated in the exacerbation of arthritis, namely progesterone and hydrocortisone, had no clinical effect. Analyses of agalactosyl IgG levels in mice with CIA, and anti-collagen II antibodies in sera collected at the end of the experiments revealed no significant differences between the oestradiol and the control groups. The successful oestradiol treatment of the mice indicates that the drop in endogenous oestradiol levels prior to delivery ends the oestrogen-mediated protection against arthritis during pregnancy.

Animals↗
PubMed1990

Characterization of the synthetic capacities of isolated placental binucleate cells from sheep and goats.

Sheep and goat binucleate cells (BNC) play a central role in placental growth and development. This study reports a simple method for isolating 60-70% pure populations of BNC of high viability. After incubation of the isolated BNC with a brief pulse of 14C-leucine or 3H-fucose or 3H-galactose, electron microscope autoradiography showed that label was eventually incorporated into the characteristic BNC granules via the Golgi body. Fucose and galactose initially showed a much higher Golgi body label than leucine, which was at first predominantly localised in the endoplasmic reticulum. 35S-methionine incorporation by BNC suspensions was extensive enough to allow an immunoprecipitation investigation which demonstrated that the protein hormone ovine placental lactogen and the SBU-3 antigen were synthesised de novo. Previous studies with isolated BNC have shown a remarkable range of substances to be released into the incubation medium but not necessarily synthesised during the incubation. The results demonstrate unequivocally that isolated BNC's are capable of total synthesis in vitro of two of the proteins that these same cells are known to secrete in vivo.

Animals↗
PubMed1990

Pregnancy-blocking progesterone antibody targets specifically the uterus through its progesterone-binding sites.

Passive immunization with a mouse monoclonal antibody against progesterone, designated DB3, blocks pregnancy in several species. We have previously reported that DB3 localizes in the mouse uterine epithelium shortly before normal implantation. This phenomenon is pregnancy dependent and specific for the progesterone antibody. In this study we demonstrate that DB3 is present in the lumen of the uterus 36 h after an i.p. injection; this correlates with the time of maximum antibody reaction on the uterine epithelium. Incubation of DB3 with free progesterone, progesterone-hemisuccinate or progesterone-bovine serum albumin before administration prevented its localization on the epithelium, indicating that the localization requires free progesterone-binding sites and thus probably depends upon progesterone binding. In addition, studies in vitro show that DB3 can effectively bind to progesterone carried by high-affinity progesterone-binding protein purified from coypu plasma. We suggest that specific targeting of DB3 may be through progesterone associated with a progesterone-binding molecule on the membrane of the uterine epithelia. This may be an important part of the mechanism of antibody action against implantation.

Animals↗
PubMed1990

Cryosurgery for the dermatology nurse.

While cryosurgery is not a panacea for all malignant skin tumors, it is a very useful tool in the armamentarium of the cancer therapist confronted with a malignancy of the skin. Cryosurgery and the nurse's role in educating patients receiving the treatment are discussed.

Cryosurgery↗
PubMed1989

A comparison of anti-type II collagen antibody titres and isotype profiles in pregnant and virgin DBA/1 mice with collagen-induced arthritis.

In order to discover whether changes in the nature of the humoral response to type II collagen occur during pregnancy we compared, by enzyme-linked immunosorbent assay (ELISA), the anti-type II collagen antibody titres and isotype profiles of pregnant and virgin DBA/1 mice immunized with type II collagen. Significant reductions in the mean clinical scores and anti-collagen antibody titres were observed during late pregnancy. Titres of all of the anti-collagen isotypes tended to be lower in pregnant than non-pregnant mice, although only in the case of IgG3 was there a significant difference between the two groups. We conclude that while pregnancy may cause changes to the isotype distribution of anti-collagen antibodies it is not possible on the basis of this study to relate such changes to the remission of arthritis observed during pregnancy.

Animals↗
PubMed1989

Detection and characterization of the fibroblast growth factor-related oncoprotein INT-2.

Products of the fibroblast growth factor-related proto-oncogene int-2 have been detected by using a monoclonal antibody and polyclonal antisera raised against synthetic peptides predicted from the DNA sequence. COS-1 monkey cells transfected with int-2 DNA linked to the simian virus 40 early promoter contained at least four int-2-specific proteins, presumably representing modified forms of the expected 27-kilodalton primary translation product. The level of expression was increased approximately six- to eightfold by mutation of sequences around the presumed initiation codon, negating their capacity to encode a short oligopeptide in the +1 reading frame. Both tunicamycin inhibition and in vitro translation experiments indicated that some of the modifications correspond to asparagine-linked glycosylation, for which the sequence predicts a single site. In line with the similarities between INT-2 and other fibroblast growth factors, the in vitro translation products functioned as weak mitogens for mammary epithelial cells.

Amino Acid Sequence↗
PubMed1989

Expression of the proto-oncogene fos (c-fos) by preimplantation blastocysts of the pig.

Blastocyst material was obtained from 25 pigs during the period 10 to 33 days post coitum, and fixed thin sections of tissue were hybridized in situ to sense and antisense fos RNA probes synthesized using the expression vector Bluescribe M13. Indirect immunofluorescence using antisera to a synthetic peptide fragment of c-fos was used to confirm the tissue distribution of oncogene-encoded proteins, which were shown by immunoprecipitation to have Mrs of 55,000 and 40,000, which are the known Mrs of the fos gene product and an associated nucleoprotein, respectively. Northern and slot blots were used to assess the distribution of c-fos mRNA and the size of the fos transcript was found to be 2.3 kbases. C-fos was expressed in trophectoderm from blastocysts early in pregnancy but declined with increasing blastocyst development so that it was virtually absent by day 19 of gestation. High levels of fos proto-oncogene expression were, however, retained in the allantoic membranes up to at least day 19 of pregnancy. The expression of the fos protein could be prolonged in trophectodermal cells in monolayer culture by addition of conditioned medium from blastocysts cultured for 2 h, suggesting the presence of a growth-factor-like substance.

Amino Acid Sequence↗
PubMed1989

Immunofluorescent localization, by use of anti-idiotypic antibody, of monoclonal anti-progesterone antibody in the mouse uterus before implantation.

Mouse monoclonal anti-progesterone IgG1 antibody designated DB3 has an anti-fertility effect when injected into female mice shortly after mating. In BALB/c mice, pregnancy is blocked, probably as a result of progesterone withdrawal with inhibition of implantation. Rabbit polyclonal anti-idiotype raised against DB3 has been used in an indirect immunofluorescence method on frozen tissue sections to demonstrate the presence of DB3 on the surface of uterine luminal and glandular epithelia before implantation. DB3 was only detectable 30-60 h after a single parenteral injection (9 nmol antibody per mouse i.p. or i.v. at 32 h post coitum). Immunolocalization was both pregnancy-dependent and anti-progesterone antibody-specific, as it was not seen in pseudopregnant mice or mice treated with P3 (mouse myeloma IgG1 protein, using polyclonal anti-P3 anti-idiotype as a probe) or saline. The immunofluorescent reaction was completely blocked by addition of DB3 idiotype in vitro. The results indicate that anti-progesterone antibody binds to an antigen associated with luminal and glandular epithelia which may locally inhibit the uterine uptake of progesterone and disrupt the process of implantation.

Animals↗
PubMed1989

Resistance to collagen-induced arthritis in DBA/1 mice by intraperitoneal administration of soluble type II collagen involves both CD4+ and CD8+ T lymphocytes.

In this paper we report that intraperitoneal administration of type II collagen in a soluble form protects DBA/1 mice against collagen-induced arthritis (CIA) on subsequent arthritogenic challenge with soluble type II collagen in adjuvant. The degree of arthritis suppression, which is expressed in terms of reduced incidence of arthritis, delayed onset and reduced anti-collagen antibody titres, depends on the dose and timing of the pre-immunization collagen injection. In order to elucidate the rôles of CD4+ and CD8+ T lymphocytes subsets in arthritis resistance we administered monoclonal antibodies (mAb) to these antigenic determinants around the time of immunization with soluble type II collagen. Anti-CD4 mAb caused abrogation of arthritis resistance while anti-CD8 mAb was less effective. However, administration of anti-CD8 mAb two weeks after pre-immunization with soluble collagen was very effective in reversing arthritis resistance. From these findings we conclude that CD4+ and CD8+ T cells are involved in resistance to arthritis though the relative importance of each subset changes during the course of the process leading to resistance to CIA.

Animals↗
PubMed1988

Bromocriptine suppresses postpartum exacerbation of collagen-induced arthritis.

We administered bromocriptine (Parlodel) to arthritic mice immediately postpartum, and found that the drug suppressed the clinical exacerbation of joint involvement that was seen in untreated animals. Approximately 50% reduction in severity of disease was achieved with bromocriptine (P less than 0.001). The effect may be due to suppression of the prolactin release that normally occurs postpartum.

Animals↗
PubMed1988

Anticollagen antibody responses in DBA/1 (H-2q) mice associated with type II collagen-induced arthritis and the effect of pregnancy.

We have previously shown that DBA/1 mice immunized with heterologous type II collagen showed remission of the subsequent collagen-induced arthritis (CIA) when pregnant, but experienced exacerbation postpartum. Measurement of anticollagen antibody (aCa) responses by ELISA in primiparous mice immunized at day 1 of pregnancy revealed no significant difference compared to aCa titres in virgin animals, apart from slightly increased titres following the primary immunisation. When mice received collagen challenge during early pregnancy, however, the date at which maximal antibody titres was reached was delayed by 5 days. Pregnancy initiated following the intraperitoneal boost caused a ten-fold suppression in aCa titres with a rise post-partum. Measurements of aCa levels in individuals which showed fetal resorption indicated that suppression of humoral responses was dependent on the presence of a viable conceptus. Antibody titres declined in all animals after a period of time, which was more prolonged in multigravidae where aCa titres were higher than in nulliparous and primiparous mice. The results show that although pregnancy alters aCa responses during the course of gestation, no long-term modification of humoral immunity occurs, an observation in agreement with the clinical findings in these mice and in humans.

Animals↗
PubMed1988

Anti-idiotypic antibody used for the localization of parenterally administered monoclonal anti-progesterone antibody in mice.

Affinity-purified rabbit and sheep anti-idiotypic antisera raised against mouse monoclonal anti-progesterone IgG1 antibody (DB3) or mouse myeloma IgG1 protein P3 (MOPC 21) showed high binding specificities to the respective idiotypes used for immunization as determined by RIA or ELISA. They have been used in an indirect immunofluorescent method to demonstrate the localization of parenterally administered idiotypes in pregnant or pseudopregnant BALB/c mouse frozen tissue preparations, at known stages post coitum after a single intraperitoneal or intravenous injection of DB3 or P3. DB3 was visualized on the surface of uterine luminal and glandular epithelia of pregnant mice 36 h after treatment; the localization was DB3-specific as it was not seen in mice treated with P3 (using sheep anti-P3 anti-idiotype as a probe) or saline. The fluorescent staining reaction in oviduct was weak and only appeared on the surface of the oviducal serosa (peritoneal side). Both DB3 and P3 were also localized in liver (granules of Kupffer cells), kidney (glomerular basement membrane), spleen (on the membrane surface of mononuclear cells in the white pulp), and peritoneal exudate cells (on the membrane surface). Staining could be completely blocked by the addition of the free idiotypes against which the anti-idiotypes were made but not by the unrelated idiotype. Anti-idiotypic labelling in vivo is more specific and selective than anti-whole immunoglobulin labelling.

Animals↗
PubMed1987

Levels of serum amyloid P-component associated with pregnancy and collagen-induced arthritis in DBA/1 (H-2q) mice.

The levels of the acute-phase reactant serum amyloid P-component (SAP) were measured by quantitative rocket immunoelectrophoresis in pregnant and non-pregnant DBA/1 female mice with or without collagen-induced rheumatoid arthritis (CIA). Non-pregnant animals with CIA showed elevated SAP titres related to the severity of the disease. Pregnancy alone also caused increased SAP levels equivalent to those found in animals with established CIA but which were virgin. The clinical remission seen in arthritic animals during pregnancy was not associated with reductions in circulating SAP levels. Increasing parity, however, caused a lowering of SAP levels in animals with or without CIA compared to the primiparous individuals. Pregnancy causes a strain-dependent elevation of serum SAP which is not further elevated by CIA, thus limiting the usefulness of SAP measurements in assessment of disease progression or remission during gestation.

Animals↗
PubMed1987

Lectin-binding characteristics of mouse oviduct and uterus associated with pregnancy block by autologous antiprogesterone monoclonal antibody.

Oviducts and uteri were removed from BALB/cJ and F1 (CBA/Ca X BALB/cJ) mice at known stages post coitum and following treatment with an antiprogesterone monoclonal antibody (DB3) or a non-specific immunoglobulin (DNP). Thin sections of tissue were prepared and reacted with fluorescent conjugates of a wide range of lectins to determine if saccharide alterations were associated with the pregnancy-inhibiting effect of the DB3 antibody in BALB/c, but not F1, individuals. The ampullary region of the DB3-treated BALB/c mice showed the most marked changes, with an almost total inhibition of lectin binding, particularly for N-acetylglucosamine residues. There was also a reduced affinity for a lectin reactive with N-acetylgalactosamine in the uteri of DB3-treated BALB/c mice, associated with an extended expression during gestation of this saccharide in the proximal region of the oviduct in such mice. These are the first biochemical alterations in reproductive tract epithelia to be associated with the efficacy of the DB3 antibody in preventing pregnancy.

Animals↗
PubMed1987

Effect of pregnancy on collagen-induced arthritis in mice.

Bovine type II collagen administered to non-pregnant female DBA/1 mice caused arthritis in 55% of animals with a mean onset time of 70 days following immunization. Of collagen-treated females subsequently becoming syngeneically pregnant before the onset of arthritis, all developed the disease within 10 days of parturition, representing an earlier onset, compared to non-pregnant females, of 41 days. This earlier onset also occurred in females with an allogenic pregnancy, but did not occur in females resorbing their fetuses (only syngeneic pregnancies were examined). In females with arthritis at the time of conception a significant remission was observed during pregnancy followed by exacerbation post-partum. This sequence of remissions during pregnancy and exacerbations post-partum occurred with each pregnancy (parties of up to four studied). The treatment of multiparous females with collagen demonstrated that pregnancy does not provide long-term protection against the development or progression of arthritis, as such females were equally susceptible to post-partum onset of collagen-induced arthritis (CIA) and the remissions and exacerbations described above. The modifying effect of pregnancy on CIA in mice is complex and does not appear to be the result of a single pregnancy-associated phenomenon.

Animals↗