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David A Clark

Publications and source records attributed to David A Clark.

At least 37 records · Page 2Linked to original sources
PubMed2004

The fgl2 prothrombinase/fibroleukin gene is required for lipopolysaccharide-triggered abortions and for normal mouse reproduction.

Increased fgl2 prothrombinase activity in maternal decidua and fetal trophoblasts may trigger abortions by proinflammatory cytokines induced by bacterial lipopolysaccharide (LPS) in mice and is implicated in human recurrent miscarriages and pre-eclampsia. Defining the physiological and pathological role of the fgl2/fibroleukin gene required an fgl2-knockout mouse and data on normal pattern of fgl2 expression during pregnancy. Expression of fgl2 protein was determined by immunostaining with specific antibody. Fgl2 knockout mice were generated and typed by PCR for presence of the altered gene. Immunostaining of timed CBAxDBA/2 mouse matings in a low-abortion-rate colony showed a distinct pattern of development of fgl2 protein expression in maternal decidua, and in embryonic tissues in early pregnancy. Outbred (mixed background) heterozygous fgl2 +/-x+/- matings with a similar low abortion rate showed selective occult loss of both +/- and, to a greater extent, -/- embryos prior to gestation day 11.5, in association with haemorrhage at the anti-mesometrial pole of fgl2-deficient embryo. LPS injected on day 6.5 caused classical abortions at mid-pregnancy in fgl2 +/+x+/+ matings, but not -/-x-/- matings. Physiological expression of fgl2 in fetal trophoblast may prevent occult loss in early pregnancy, along with other coagulation factors, but fgl2 expression is required for LPS to induce abortion pathology.

Abortion, Spontaneous↗
PubMed2004

Structural and functional heterogeneity in the CD200R family of immunoregulatory molecules and their expression at the feto-maternal interface.

PROBLEM: We have shown that CD200Fc, a chimeric molecule including the extracellular domain of CD200 and a murine immunoglobulin (Ig)G2a Fc region, regulates immune responses and prevents T helper (Th)1 cytokine-triggered spontaneous abortions in mice. CD200 is expressed on a subpopulation of uterine decidua cells and on trophoblast, both in the mouse and human. The receptor(s) for CD200, CD200R(s), was not previously well-characterized. METHODS: 5'-rapid amplification of cDNA ends (RACE), cDNA and genomic DNA clone analysis were used to identify a family of CD200Rs on mouse chromosome 16, juxtaposed to the CD200 gene, named CD200R1, R2, R3, and R4. Northern blot and reverse transcriptase polymerase chain reaction (RT-PCR) analysis was used to detect expression of different CD200R subtypes in different organs. Rabbit polyclonal and rat monoclonal antibodies (mAbs) to CD200R isoforms was used for fluorescence-activated cell sorter (FACS) analysis, to test for immunomodulatory effects on allogeneic mixed-lymphocyte responses in vitro, and for immunohistochemistry. RESULTS: The CD200Fc was able to interact physically with each of the CD200Rs expressed on the cell surface. Northern blot and RT-PCR analyses indicated distinct patterns of CD200R isoform mRNA expression in different tissues and FACS analyses confirmed unique cell- and tissue-specific expression of the different CD200Rs. mAbs directed against the different isoforms modified the development of in vitro alloimmune responses. The addition of anti-CD200R1/R4 elicited immunomodulatory responses in vitro comparable to findings with CD200Fc, but different from the effects of anti-CD200R2-3. CONCLUSIONS: These data provide evidence for a family of CD200R molecules in the mouse genome and defines the existence of previously unrecognized diversity in the CD200/CD200R immunomodulatory gene member family. Although this gene member family is clustered in the genome, the different CD200Rs and CD200 exhibit distinct expression patterns and functional properties. Restricted CD200R isoform expression at the feto-maternal interface suggests CD200:CD200R interactions may serve important function(s) determining the successful outcome of pregnancy.

Amino Acid Sequence↗
PubMed2004

Ecology of danger-dependent cytokine-boosted spontaneous abortion in the CBA x DBA/2 mouse model. I. Synergistic effect of LPS and (TNF-alpha + IFN-gamma) on pregnancy loss.

PROBLEM: Previous data have shown "danger" signals, such as bacterial lipopolysaccharide (LPS) acting via toll-like (tlr) receptors are required for early pregnancy failure in several murine abortion models. Indeed, the abortion rate increased in the CBA x DBA/2 model after a gestation day (gd) 7.5 injection of tumour necrosis factor (TNF)-alpha + interferon (IFN)-gamma only if the LPS-tlr signalling pathway was intact. High rates of cytokine-boosted abortion >80% loss can be achieved in certain animal colonies, that have a high endogenous (spontaneous) rate of resorption (30-50%). A specific role for LPS has been postulated to determine both the endogenous and cytokine-boosted losses. METHODS: To test the role of LPS in spontaneous and cytokine-boosted abortions, recombinant TNF-alpha + IFN-gamma, and LPS were injected in different doses and sequences intraperitoneally (i.p.) into CBA x DBA/2 mated mice in the Toronto General Research Institute animal facility where the endogenous abortion rate is <30%. The effects of poly IC, a tlr3 agonist that induces IFN-gamma that can reverse LPS-induced tolerance, and effects of anti-MD-1 on TNF-alpha induction by LPS, poly IC, CPG, or HSP in vitro were also examined. RESULTS: A high endogenous rate of loss similar to that seen in Clamart could be achieved by increasing exposure to LPS on the morning after mating (gd 0.5). The magnitude by which the abortion rate could be increased by an i.p. injection of 2000 u TNF-alpha + 1000 u IFN-gamma on gd 7.5 was independent of the endogenous rate of loss, and could not be increased by doubling the dose. One microgram of LPS given on day 7.5 achieved a similar rate of loss, and if given with the cytokines, synergistically boosted the rate of loss to near Clamart rates. LPS given 1 day prior to the cytokines abrogated the cytokine effect, whereas LPS given day 0.5 had no significant effect on the response to day 7.5 cytokine injection. Blocking MD-1 inhibited TNF-alpha stimulation by poly IC, LPS, CPG, or HSP in vitro, and reduced abortion rates. Poly IC did not avert LPS-type tolerance effects in vivo. CONCLUSIONS: High endogenous rates of abortion in the CBA x DBA/2 model may be explained by exposure to LPS at the time of mating. Increased rates of loss triggered by cytokines later in pregnancy may depend on increased absorption of LPS from intestinal flora.

Abortion, Spontaneous↗
PubMed2003

Scalp hair characteristics in the newborn infant.

Scalp hair growth and patterning are closely associated with the development of the central nervous system. A number of genetic, metabolic, and neurologic disorders are associated with recognizable scalp hair abnormalities. For this reason, a systematic step-by-step assessment of the hair and scalp should be an integral part of every initial newborn physical assessment. This article reviews the clinically relevant embryology related to fetal scalp hair formation. Normal cycles of hair growth and loss are discussed. A systematic review of typical newborn scalp hair characteristics such as color, quantity, texture, direction of growth, hairlines, and hair whorls is provided. Conditions associated with abnormal hair color, quality, quantity, and distribution are presented in a series of clinical photographs, and their salient features are discussed. Abnormal hair often occurs as a constellation of findings; implications for clinical care and further investigation will be briefly described.

Hair↗
PubMed2003

A critical analysis of the routine testing of newborn stools for occult blood and reducing substances.

Stool tests for occult blood or reducing substances were introduced in the neonatal intensive care unit (NICU) as potential aids in the early recognition of necrotizing enterocolitis (NEC) in high-risk neonates, and have been recommended by some as routine nursing procedures. Neither the performance characteristics of these tests with respect to NEC, nor their indirect impact, were evaluated formally before widespread adoption into clinical care. The published evidence suggests that these tests are not useful as diagnostic or screening tools. There is no evidence that routine stool screening for occult blood or reducing substances predicts NEC or decreases the rate or severity of this disease. The direct costs of the tests are significant. A greater concern is their potential unintended consequences, which include the cost of secondary tests, restricted nutritional intake, and the accumulation of distracting, useless data. The logistics of maintaining quality control, the demands on nursing time, and the cost of testing are increasingly important considerations. This installment of Focus on the Physical diverges from a step-by-step systematic physical assessment by addressing the utility of testing neonatal stools for occult blood and reducing substances as aids in the early diagnosis or prevention of NEC. Using the information from these tests requires a framework for understanding their rationale, the test performance characteristics in the NICU setting, and the potential benefits, costs, and risks of their routine use.

Enteral Nutrition↗
PubMed2003

Is there any evidence for immunologically mediated or immunologically modifiable early pregnancy failure?

PURPOSE: Human reproduction is an inefficient process. There is a high rate of loss of early pregnancies, often before the mother (or physician) knows she is pregnant. Genetic abnormalities can explain much of the wastage, but can it explain all of the failures? As embryos bear paternal and embryonic antigens foreign to the maternal immune system, could some otherwise normal embryos be "rejected"? METHODS: Critical review of existing data. RESULTS AND CONCLUSIONS: Otherwise normal embryos can fail prior to implantation, at implantation, in the periimplantation period as occult/chemical pregnancies, and as clinically evident miscarriages. The maternal immune system and its products (e.g., cytokines) can have innocent bystander effects, and a good case for direct recognition and "rejection" can also be made. The tools needed for accurate clinical diagnosis of such situations require further development and validation. Deliberate modification of the maternal host defence system can improve the chance of success, but the best evidence for efficacy of immunotherapeutic interventions is the situation of recurrent spontaneous abortions, which constitutes only a small percentage of losses. There is also evidence of clinical efficacy for several types of treatment to improve implantation and early pregnancy success.

Abortion, Habitual↗
PubMed2003

MD-1 is a critical part of the mechanism causing Th1-cytokine-triggered murine fetal loss syndrome.

PROBLEM: Fetal loss syndrome (abortion/resorption) occurring on or after gestation day (gd) 9.5 in CBA/JxDBA/2 matings is dependent upon presence of TNF-alpha + IFN-gamma, which act by increasing expression of fg12 prothrombinase at the feto-maternal interface. The magnitude by which the abortion rate can be boosted by an injection of these cytokines on gd 7.5 depends on endogenous rate of loss, and appears to depend on microbial flora. Is cytokine-triggered abortion dependent upon a third signaling pathway that senses 'danger'? METHODS: Female CBA/J were mated to DBA/2 males and, C57B1/6 and C57B1/6 TNFalphaR1-/-Mak were mated to C57B1/6 control or TNFalphaR1-/-Mak males. LPS from Escherichia coli and Salmonella enteritidis, or the combination of TNF-alpha + IFN-gamma, was injected to stimulate abortions. The effect of anti-MD-1, which interferes with expression of CD14 and, hence, with signaling by LPS via the CD14-tlr4 complex, on TNF-alpha + IFN-gamma was tested. The presence of MD-1 in the uterus was evaluated by in situ hybridization, and effect of lipopolysaccharide (LPS) on mice lacking TNF-alphaR1 was tested. RESULTS: Anti-MD-1 completely abrogated TNF-alpha + IFN-gamma-induced abortions. MD-1 was expressed on trophoblast and in deciduas on gd 8.5 but LPS could not abort mice that lacked the type 1 receptor for TNF-alpha. Pregnant CBA/J females had classical resorptions (abortions) countable on gd 13.5-14.5 in response to LPS from E. coli or S. enteritidis, but C57B1/6 strain mice resorbed only in response to the latter, and E. coli LPS appeared to induce 'occult' losses. 'Occult' loss did not require TNF-alphaR1. CONCLUSIONS: TNF-alpha + IFN-gamma could not induce murine abortions without co-presence of a 'danger' signal such as LPS acting via CD14 on toll receptors, and LPS could not act without co-signaling by TNF-alpha. Classical resorptions/abortions and 'occult' losses have a different mechanism in these models as reflected in type of endotoxin and requirement for TNF-alphaR1 signaling.

Abortion, Spontaneous↗
PubMed2003

Placental trophoblast from successful human pregnancies expresses the tolerance signaling molecule, CD200 (OX-2).

PROBLEM: Th1 cytokine-dependent abortions in the CBA x DBA/2 mouse model have been linked to down-regulation of expression of the CD200 (OX-2) 'tolerance' signal on trophoblast and in decidua prior to onset of the abortion process. Abortions could be prevented by administration of a soluble CD200. Is CD200 expressed on trophoblast in successful human pregnancy? METHOD OF STUDY: As one cannot easily obtain trophoblasts in large quantities from successful human pregnancies in the first trimester prior to the onset of the abortion process at 6 weeks gestation, we examined as a first step, trophoblast isolated from term placentae (i.e. successful pregnancies). CD9- trophoblasts were isolated by affinity column and stained for intracellular cytokeratin, and surface CD200 using PE-anti-human CD200 monoclonal antibody. mRNA was extracted from CD9+ and CD9- cells and tested by reverse transcription-polymerase chain reaction for CD200 mRNA. CD9- placental cells were separated by velocity sedimentation and test for CD200-dependent suppression of an allogeneic human mixed lymphocyte culture where cytotoxic T cell (CTL) generation, and Thl --> Th2 cytokine production shift were measured. RESULTS: CD9- but not CD9+ placental cell populations contained cells with mRNA for CD200, both a normal length transcript and a truncated transcript. Flow cytometry showed a CD200+ cytokeratin+ moderate-to-large-sized cell population compatible with trophoblasts and a smaller subset of cytokeratin- cells that expressed CD200 at normal and at high levels. The moderate-sized population proved most potent at inhibiting CTL generation and caused a Th1 --> Th2 cytokine shift. These effects were blocked by monoclonal anti-CD200. CONCLUSIONS: A subpopulation of cytokeratin+ placental trophoblasts express bioactive CD200 able to alter maternal immune responses in a favorable (Th2 > Th1) direction. Two populations of CD200+ small- and medium-small-sized cytokeratin- placental cells remain to be identified. Studies of karyotyped first trimester elective termination and spontaneous miscarriage tissues are needed.

Animals↗
PubMed2003

Nutrition in the neonatal intensive care unit: how do we reduce the incidence of extrauterine growth restriction?

Extrauterine growth restriction is a major clinical problem for prematurely born neonates, especially critically ill preterm neonates, and malnutrition in the neonatal intensive-care unit remains common. There are numerous perceived risks to initiation of adequate nutritional support. How many of these factors pose a real risk to health outcomes is less clear. Current nutritional support does not prevent extrauterine growth restriction and the consequences of malnutrition are both acute and delayed. Our clinical approach to providing nutritional support impacts neonatal morbidity and long-term neuro developmental outcomes. While more and better evidence is needed to help guide best practices, this gap should not prevent neonatologists from using the observations in this review to improve their current practice. There is evidence that changes in nutritional support can have a positive influence on growth. These include early administration of intravenous amino acids and lipids, minimal enteral nutrition, and supplemented formula and human milk. Simply recognizing the degree of growth failure by monitoring weight and focusing on the accruing deficit should encourage clinicians to increase nutritional support to enhance recovery growth. Continued research is needed to define the efficiency of early feeding, more rapid advancements in nutritional support, protein needs, the optimal composition of breast-milk supplements, the etiology of necrotizing enterocolitis, and perhaps most importantly, the health consequences of extrauterine growth restriction.

Growth Disorders↗
PubMed2003

Gene transcription of fgl2 in endothelial cells is controlled by Ets-1 and Oct-1 and requires the presence of both Sp1 and Sp3.

The immune coagulant fgl2/fibroleukin has been previously shown to play a pivotal role in the pathogenesis of murine and human fulminant hepatitis and fetal loss syndrome. Constitutive expression of fgl2 transcripts at low levels are seen in cytotoxic T cells, endothelial, intestinal and trophoblast cells, while specific factors (such as virus and cytokines) are required to induce high levels of fgl2 expression in other cell types including monocytes/macrophages. To address the transcriptional mechanisms that regulate constitutive expression of fgl2, murine genomic clones were characterized and the transcription start site was defined by 5'-RACE and primer extension. A comprehensive assessment of basal fgl2 promoter activity in murine vascular endothelial cells defined a minimal 119 bp region responsible for constitutive fgl2 transcription. A complex positive regulatory domain (PRD) spanning a 39-bp sequence from -87 to -49 (relative to the transcription start site) was identified. Electrophoretic mobility shift assay studies in vascular endothelial cells revealed that the nucleoprotein complexes that form on this positive regulatory domain (PRD) contain Sp1/Sp3 family members, Oct-1, and Ets-1. Heterologous expression studies in Drosophila Schneider cells confirmed that the constitutive expression of this gene is controlled by Ets-1 and requires the presence both of the Sp1 and Sp3 transcription factors. The presence of this complex multicomponent PRD in the fgl2 proximal promoter is consistent with the observation that, in vivo, fgl2 expression is tightly regulated. Moreover, viral induced fgl2 expression also requires the presence of this PRD. These results clearly demonstrate that multiple cis DNA elements in a clustered region work cooperatively to regulate constitutive fgl2 expression and interact with inducible elements to regulate viral-induced fgl2 expression in endothelial cells.

Animals↗
PubMed2003

Assessing human alloimmunization as a strategy for inducing HIV type 1 neutralizing anti-HLA responses.

Xenovaccination of rhesus macaques with human HLA Class I and II proteins has been demonstrated to elicit protective immunity against challenge with SIV grown in human cells. To determine if alloimmunization in humans could lead to protective immunity against HIV-1, we prospectively followed a small group of women receiving whole-cell alloimmunization in the form of leukocyte immunotherapy for recurrent spontaneous abortion. Whole-cell vaccine recipients and their respective partners (referred to as donors) provided pre- and postimmune blood samples for analysis. Study participants were HLA typed by sequence-specific PCR and antibodies specific for HLA Class I and II antigens were measured in recipient plasma. To determine if anti-HLA antibody responses detected in recipient plasma samples were capable of neutralizing HIV-1 in vitro, we grew laboratory strain HIV-1(IIIB) and primary isolate HIV-1(301660) in donor-derived CD4(+) T lymphocytes. The ability of purified whole IgG from responding patients to neutralizing infectivity of the respective donor-derived virus was then assayed in vitro. All donor-recipient pairs were determined to be HLA discordant for at least one Class I and one Class II locus. Two of seven female recipients in total made strong anti-HLA antibody responses specific to the HLA haplotype of the male donor in response to the alloimmunization regimen. For one recipient, IgG antibodies specific for donor HLA Class I and II antigens were able to neutralize both HIV-1(IIIB) and a primary isolate HIV-1(301660). In addition polyclonal anti-HLA class II antibodies against a single determinant (DR4) of this donor were also neutralizing. In contrast, the other recipient exhibiting antibodies only against donor HLA Class I antigens did not neutralize HIV-1(IIIB). Using samples from a small number of women undergoing leukocyte immunotherapy, we have demonstrated for the first time that allele-specific anti-HLA antibodies elicited through human alloimmunization are capable of neutralizing HIV-1 in vitro.

Abortion, Spontaneous↗
PubMed2003

The Fgl2/fibroleukin prothrombinase contributes to immunologically mediated thrombosis in experimental and human viral hepatitis.

Fibrin deposition and thrombosis within the microvasculature is now appreciated to play a pivotal role in the hepatocellular injury observed in experimental and human viral hepatitis. Importantly, the pathways by which fibrin generation is elicited in viral hepatitis may be mechanistically distinct from the classical pathways of coagulation induced by mechanical trauma or bacterial lipopolysaccharide (LPS). In the setting of murine hepatitis virus strain-3 (MHV-3) infection, a member of the Coronaviridae, activated endothelial cells and macrophages express distinct cell-surface procoagulants, including a novel prothrombinase, Fgl2/fibroleukin, which are important for both the initiation and localization of fibrin deposition. To assess the role of Fgl2/fibroleukin in murine viral hepatitis we generated a Fgl2/fibroleukin-deficient mouse. Peritoneal macrophages isolated from Fgl2/fibroleukin-/- mice did not generate a procoagulant response when infected with MHV-3. Fibrin deposition and liver necrosis were markedly reduced, and survival was increased in mice infected with MHV-3. To address the relevance of Fgl2/fibroleukin in human chronic viral hepatitis we studied patients with minimal and marked chronic hepatitis B. We detected robust expression of Fgl2/fibroleukin mRNA transcripts and protein in liver tissue isolated from patients with marked chronic hepatitis B. Fibrin deposition was strongly associated with Fgl2/fibroleukin expression. Collectively, these data indicate a critical role for Fgl2/fibroleukin in the pathophysiology of experimental and human viral hepatitis.

Adult↗
PubMed2002

Kinetic analysis of a unique direct prothrombinase, fgl2, and identification of a serine residue critical for the prothrombinase activity.

fgl2 prothrombinase, by its ability to generate thrombin, has been shown to be pivotal to the pathogenesis of viral-induced hepatitis, cytokine-induced fetal loss syndrome, and xeno- and allograft rejection. In this study, the molecular basis of fgl2 prothrombinase activity was examined in detail. Purified fgl2 protein generated in a baculovirus expression system had no measurable prothrombinase activity, whereas the activity was restored when the purified protein was reconstituted into phosphatidyl-L-serine-containing vesicles. Reconstituted fgl2 catalyzed the cleavage of human prothrombin to thrombin with kinetics consistent with a first order reaction, with an apparent V(max) value of 6 mol/min/mol fgl2 and an apparent K(m) value for prothrombin of 8.3 microM. The catalytic activity was totally dependent on calcium, and factor Va (500 nM) enhanced the catalytic efficiency of fgl2 by increasing the apparent V(max) value to 3670 mol/min/mol fgl2 and decreasing the apparent K(m) value for prothrombin to 7.2 microM. By a combination of site-directed mutagenesis and production of truncated proteins, it was clearly shown that residue Ser(89) was critical for the prothrombinase activity of fgl2. Furthermore, fgl2 prothrombinase activity was not inhibited by antithrombin III, soybean trypsin inhibitor, 4-aminobenzamidine, aprotinin, or phenylmethylsulfonyl fluoride, whereas diisopropylfluorophosphate completely abrogated the activity. In this work we provide direct evidence that fgl2 cleaves prothrombin to thrombin consistent with serine protease activity and requires calcium, phospholipids, and factor Va for its full activity.

Animals↗
PubMed2002

Thinking outside the box: mechanisms of environmental selective pressures on the outcome of the materno-fetal relationship.

PROBLEM: Study of mechanisms causing spontaneous abortion of the vascularized placenta have focused primarily on the feto-maternal immunological relationship within the pregnant mother. The Th1 cytokines such as tumor necrosis factor (TNF)-alpha + interferon (IFN)-gamma derived in part from natural killer (NK) and NKgammadeltaT cells have been implicated in causing abortion via up-regulation of the novel prothrombinase fgl2 at the feto-maternal interface; Th2/3 cytokines such as interleukin (IL)-10, progesterone-induced blocking factor (PIBF), and TGF-beta2 derived from gammadeltaT cells stimulated by embryo antigens in the context of the OX-2 (CD200) tolerance signal have been viewed as counteracting the Th1 effect. These mechanisms are distinct from those causing and preventing occult pregnancy loss during the periimplantation phase of pregnancy prior to development of a vascularized placenta. Spontaneous abortions in the CBA/J x DBA/2 can be boosted by injecting TNF-alpha + IFN-gamma, but the boosted abortion rates can range from < or = 30 to > 80%, depending on the loss rate in uninjected mice, and this is not explainable by the endogenous level of these cytokines. Furthermore, there is a poor correlation between Th1/Th2.3 cytokine ratios and abortion rates. Could there be a third factor involved, and if so, what might this mean? METHODS: Known precipitants of recurrent abortion in mice were reviewed with particular attention to stress and endotoxin absorption. The effect of antagonizing the response to bacterial lipopolysaccharide (LPS) (endotoxin) was tested. Data on environmental selective pressures were considered (i.e. thinking outside the 'box', which typifies the conventional approach to thinking about materno-fetal interactions). RESULTS: Th1 cytokine-triggered abortions appear to depend on availability/presence of LPS. CONCLUSIONS: Environmental selective pressures are implicated in eliminating 'genetically weaker' embryos in early pregnancy.

Abortion, Habitual↗
PubMed2002

The same immunoregulatory molecules contribute to successful pregnancy and transplantation.

PROBLEM: At least two dendritic cell-associated molecules have been shown to contribute to the successful outcome of organ and tissue allografts in mice, namely CD200 and MD-1. CD200 is up-regulated in rodent transplantation models where successful inhibition of rejection is accomplished, and is believed to signal immunosuppression following engagement of a receptor, CD200R, on macrophages and/or gammadelta T-cell receptor (gammadelta TCR+ cells MD-1 is implicated in controlling expression of costimulatory molecules including CD80/CD86 which induce an immunorejection response, and thus inhibition of MD-1 expression also facilitates increased graft survival MD-1 also stabilizes expression of CD14, part of the receptor complex for LPS. As well as the inhibition of rejection which follows blockade of MD-1 expression and/or augmentation of CD200 expression, an altered polarization in cytokine production is seen, with increased expression of interleukin-4 (IL-4), IL-10 and transforming growth factor-beta (TGF-beta), and decreased IL-2, interferon-gamma (IFN-gamma) and tumor nerosis factor-alpha (TNF-alpha). Successful pregnancy in allopregnant mice also depends upon control of graft rejection mechanisms. Proinflammatory T-helper 1 (Th1) cytokines (TNF-alpha + IFN-gamma + IL-1) have been shown to cause spontaneous abortion in mice by activating a novel prothrombinase, fibrinogen-like peptide (fibroleukin) fgl2, which may promote fibrin deposition in the graft rejection process; expression of IL-10, TGF-beta, and progesterone-induced blocking factor (PIBF) in contrast leads to lowering of abortion rates. Interestingly, the spontaneous abortion rates in abortion-prone CBA x DBA/2 matings and in the low abortion rate CBA x BALB/c matings were lower than the frequency of implantation sites showing fibrin(hi) + fgl2 (mRNA)hi, implying regulation of the pro-abortion consequences of fgl2 expression. METHODS: We have investigated, by in situ hybridization, CD200, MD-1 and fgl2 expression in implantation sites in different strains of mice, and studied the effects of anti-MD-1, anti-CD200 and CD200Fc immunoadhesin on fetal and allograft survival. The role of indoleamine dioxygenase (IDO) was evaluated. RESULTS: CD200 mRNA expression occurred in the same sites as fgl2 mRNA. Anti-CD200 antibody raised the abortion rate to predicted levels, and infusion of a CD200 immunoadhesin reduced the abortion rate, as did an anti-MD-1 antibody. The latter also improved organ and tissue graft survival. Suppression by antigen-presenting macrophages triggered by CD200 is dependent upon intact IDO activity. CONCLUSION: Regulation of CD200 and MD-1 expression may control both pregnancy and allograft survival.

Animals↗
PubMed2002

Look before you clamp: delivery room examination of the umbilical cord.

The umbilical cord is a critical connection between the embryo (and later, the fetus) and the placenta. The umbilical cord houses the blood vessels that are responsible for nourishing the fetus. Proper umbilical cord function is essential for growth and development before birth. A review of the embryologic origin of the umbilical cord aids in understanding abdominal wall and umbilical cord defects that can present in the newborn period. In the delivery room, inspection of the umbilical cord is an integral part of the first minutes of life. Any abnormality either within the cord structure or in the areas surrounding the base of the cord may necessitate a delay in shortening the cord. Surgical consultation may also be indicated. This issue of Focus on the Physical will provide a step-by-step guide to cord assessment in the delivery room setting. Pictures showing normal, atypical, and abnormal umbilical cords and common abdominal wall defects will be presented along with a brief discussion of the significance and clinical implications of each of these findings.

Abdominal Wall↗