Biomedical subjects

Chun Lam

Publications and source records attributed to Chun Lam.

10 recordsLinked to original sources

PubMed2006

Soluble endoglin and other circulating antiangiogenic factors in preeclampsia.

BACKGROUND: Alterations in circulating soluble fms-like tyrosine kinase 1 (sFlt1), an antiangiogenic protein, and placental growth factor (PlGF), a proangiogenic protein, appear to be involved in the pathogenesis of preeclampsia. Since soluble endoglin, another antiangiogenic protein, acts together with sFlt1 to induce a severe preeclampsia-like syndrome in pregnant rats, we examined whether it is associated with preeclampsia in women. METHODS: We performed a nested case-control study of healthy nulliparous women within the Calcium for Preeclampsia Prevention trial. The study included all 72 women who had preterm preeclampsia (<37 weeks), as well as 480 randomly selected women--120 women with preeclampsia at term (at > or =37 weeks), 120 women with gestational hypertension, 120 normotensive women who delivered infants who were small for gestational age, and 120 normotensive controls who delivered infants who were not small for gestational age. RESULTS: Circulating soluble endoglin levels increased markedly beginning 2 to 3 months before the onset of preeclampsia. After the onset of clinical disease, the mean serum level in women with preterm preeclampsia was 46.4 ng per milliliter, as compared with 9.8 ng per milliliter in controls (P<0.001). The mean serum level in women with preeclampsia at term was 31.0 ng per milliliter, as compared with 13.3 ng per milliliter in controls (P<0.001). Beginning at 17 weeks through 20 weeks of gestation, soluble endoglin levels were significantly higher in women in whom preterm preeclampsia later developed than in controls (10.2 ng per milliliter vs. 5.8 ng per milliliter, P<0.001), and at 25 through 28 weeks of gestation, the levels were significantly higher in women in whom term preeclampsia developed than in controls (8.5 ng per milliliter vs. 5.9 ng per milliliter, P<0.001). An increased level of soluble endoglin was usually accompanied by an increased ratio of sFlt1:PlGF. The risk of preeclampsia was greatest among women in the highest quartile of the control distributions for both biomarkers but not for either biomarker alone. CONCLUSIONS: Rising circulating levels of soluble endoglin and ratios of sFlt1:PlGF herald the onset of preeclampsia.

Antigens, CD↗

PubMed2006

Soluble endoglin contributes to the pathogenesis of preeclampsia.

Preeclampsia is a pregnancy-specific hypertensive syndrome that causes substantial maternal and fetal morbidity and mortality. Maternal endothelial dysfunction mediated by excess placenta-derived soluble VEGF receptor 1 (sVEGFR1 or sFlt1) is emerging as a prominent component in disease pathogenesis. We report a novel placenta-derived soluble TGF-beta coreceptor, endoglin (sEng), which is elevated in the sera of preeclamptic individuals, correlates with disease severity and falls after delivery. sEng inhibits formation of capillary tubes in vitro and induces vascular permeability and hypertension in vivo. Its effects in pregnant rats are amplified by coadministration of sFlt1, leading to severe preeclampsia including the HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome and restriction of fetal growth. sEng impairs binding of TGF-beta1 to its receptors and downstream signaling including effects on activation of eNOS and vasodilation, suggesting that sEng leads to dysregulated TGF-beta signaling in the vasculature. Our results suggest that sEng may act in concert with sFlt1 to induce severe preeclampsia.

Adult↗

PubMed2006

Circulating angiogenic factors and placental abruption.

OBJECTIVE: Abnormalities in circulating angiogenic factors have been reported in diseases of abnormal placentation, such as preeclampsia and intrauterine growth restriction. Our objective was to determine whether circulating angiogenic factors are altered in another placental vascular disease, abruptio placentae. METHODS: In a nested case-control study of nulliparous pregnancies, we examined levels of placental growth factor (PlGF) and soluble fms-like tyrosine kinase 1 (sFlt-1) in serum collected prospectively from 31 women who later developed placental abruption and from 31 normal control subjects. All serum specimens were collected before the onset of hypertension or abruption and before labor or delivery. Serum angiogenic factors were compared within 3 gestational age windows: early (20 weeks or less), middle (21-32 weeks), and late (33 weeks or more) pregnancy. RESULTS: During early pregnancy women who developed placental abruption had lower PlGF and higher sFlt-1 concentrations and higher sFlt-1/PlGF ratios than women with normal pregnancies. In mid-pregnancy these differences became greater, reaching statistical significance for PlGF concentration (431 versus 654 pg/mL, P<.01) and the sFlt-1/PlGF ratio (25.3 versus 2.5, P<.01). When the women with placental abruption were subdivided into those who did (n=10) and those who did not (n=21) develop preeclampsia or gestational hypertension, significant alterations in angiogenic factors were noted only in women who later developed hypertension in pregnancy. Among these women, PlGF concentrations were decreased in mid-pregnancy (160 versus 723 pg/mL, P<.001), and the mid-pregnancy sFlt-1/PlGF ratio was increased (70.1 versus 2.3, P=.001). CONCLUSION: Serum levels of the proangiogenic factor PlGF were decreased, and those of the antiangiogenic ratio sFlt-1/PlGF were increased in nulliparous women who subsequently developed hypertension and placental abruption.

Abruptio Placentae↗

PubMed2006

Late postpartum eclampsia: examples and review.

Eclampsia, defined as the occurrence of seizures in pregnant women, usually in the setting of preeclampsia and in the absence of other neurologic disorders, occurs mainly before, during , or within 48 hours after delivery. When convulsions occur later postpartum, diagnosis is difficult and treatment disputed. We review the entity of late postpartum eclampsia and report 2 examples in which the serum levels of antiangiogenic and angiogenic proteins were measured.

Abdominal Pain↗

PubMed2005

Circulating angiogenic factors in the pathogenesis and prediction of preeclampsia.

Preeclampsia is a major cause of maternal, fetal, and neonatal mortality worldwide. Although the etiology of preeclampsia is still unclear, recent studies suggest that its major phenotypes, high blood pressure and proteinuria, are due in part to excess circulating soluble fms-like tyrosine kinase-1 concentrations. Soluble fms-like tyrosine kinase-1 is an endogenous antiangiogenic protein that is made by the placenta and acts by neutralizing the proangiogenic proteins vascular endothelial growth factor and placental growth factor. High serum soluble fms-like tyrosine kinase-1 and low serum free placental growth factor and free vascular endothelial growth factor have been observed in preeclampsia. Abnormalities in these circulating angiogenic proteins are not only present during clinical preeclampsia but also antedate clinical symptoms by several weeks. Therefore, this raises the possibility of measuring circulating angiogenic proteins in the blood and the urine as a diagnostic and screening tool for preeclampsia. The availability of a test to predict preeclampsia would be a powerful tool in preventing preeclampsia-induced mortality, especially in developing nations, where high-risk specialists are limited. This review will summarize our current understanding of the role of circulating angiogenic proteins in the pathogenesis and clinical diagnosis/prediction of preeclampsia.

Angiogenesis Inducing Agents↗

PubMed2005

Urinary placental growth factor and risk of preeclampsia.

CONTEXT: Preeclampsia may be caused by an imbalance of angiogenic factors. We previously demonstrated that high serum levels of soluble fms-like tyrosine kinase 1 (sFlt1), an antiangiogenic protein, and low levels of placental growth factor (PlGF), a proangiogenic protein, predict subsequent development of preeclampsia. In the absence of glomerular disease leading to proteinuria, sFlt1 is too large a molecule to be filtered into the urine, while PlGF is readily filtered. OBJECTIVE: To test the hypothesis that urinary PlGF is reduced prior to onset of hypertension and proteinuria and that this reduction predicts preeclampsia. DESIGN, SETTING, AND PATIENTS: Nested case-control study within the Calcium for Preeclampsia Prevention trial of healthy nulliparous women enrolled at 5 US university medical centers during 1992-1995. Each woman with preeclampsia was matched to 1 normotensive control by enrollment site, gestational age at collection of the first serum specimen, and sample storage time at -70 degrees C. One hundred twenty pairs of women were randomly chosen for analysis of serum and urine specimens obtained before labor. MAIN OUTCOME MEASURE: Cross-sectional urinary PlGF concentrations, before and after normalization for urinary creatinine. RESULTS: Among normotensive controls, urinary PlGF increased during the first 2 trimesters, peaked at 29 to 32 weeks, and decreased thereafter. Among cases, before onset of preeclampsia the pattern of urinary PlGF was similar, but levels were significantly reduced beginning at 25 to 28 weeks. There were particularly large differences between controls and cases of preeclampsia with subsequent early onset of the disease or small-for-gestational-age infants. After onset of clinical disease, mean urinary PlGF in women with preeclampsia was 32 pg/mL, compared with 234 pg/mL in controls with fetuses of similar gestational age (P<.001). The adjusted odds ratio for the risk of preeclampsia to begin before 37 weeks of gestation for specimens obtained at 21 to 32 weeks, which were in the lowest quartile of control PlGF concentrations (<118 pg/mL), compared with all other quartiles, was 22.5 (95% confidence interval, 7.4-67.8). CONCLUSION: Decreased urinary PlGF at mid gestation is strongly associated with subsequent early development of preeclampsia.

Adult↗

PubMed2005

Circulating levels of the antiangiogenic marker sFLT-1 are increased in first versus second pregnancies.

Preeclampsia is far more common in women's first pregnancy but the mechanism of this association is unknown. Altered angiogenesis, marked by increased levels of circulating soluble fms-like tyrosine kinase (sFlt-1), an inhibitor of placental growth factor (PlGF) and vascular endothelial growth factor, has been implicated in the pathogenesis of preeclampsia. We tested the hypothesis that nulliparous women demonstrate increased sFlt-1 levels compared with multiparous women, suggesting an overall increase in relative antiangiogenesis during first pregnancies. We measured sFlt-1 and PlGF levels in early pregnancy serum samples from the first 2 completed pregnancies of 97 women who participated in the MOMS cohort study. Repeated measures analyses demonstrated that sFlt-1 levels were significantly increased in first compared with second pregnancies (877+/-598 pg/mL vs 728+/-399 pg/mL; P=.01) but there was no significant difference in PlGF levels (45.3+/-40.7 pg/mL vs 40.1+/-31.9 pg/mL; P=.14). After adjusting for age, gestational age, blood pressure, body mass index, smoking, and the interpregnancy time interval, the residual decrease in sFlt-1 levels from the first to the second pregnancy remained significant at 107 pg/mL (P=.04). Significant interaction between ethnicity and pregnancy order on sFlt-1 levels was observed such that Hispanic women demonstrated greater sFlt-1 levels than white women during their first pregnancy but lower levels in their second pregnancies. Increased sFlt-1 secretion in first versus second pregnancies may account in part for the increased risk of preeclampsia among nulliparous women. Additional studies are needed to verify these findings and to further examine ethnic differences in angiogenesis factors and their potential impact on the incidence of preeclampsia.

Adult↗

PubMed2005

Uric acid and preeclampsia.

Increased uric acid level is a key clinical feature of preeclampsia; higher levels correlate with significant maternal and fetal morbidity and mortality. The cause of hyperuricemia and its specific role in the pathogenesis of preeclampsia, however, remain unclear. Although uric acid has been shown to roughly parallel the severity of the maternal syndrome, it has not been useful in predicting the development of preeclampsia. Nevertheless, there have been recent data supporting a pathogenic role potentially in the hypertension and endothelial cell dysfunction of preeclampsia. This article reviews our current understanding of hyperuricemia in the setting of preeclampsia, and highlights the hypothesis that hyperuricemia may contribute to vascular damage in preeclampsia.

Animals↗

PubMed2004

Preeclampsia and future cardiovascular disease: potential role of altered angiogenesis and insulin resistance.

Altered angiogenesis and insulin resistance are associated with preeclampsia and cardiovascular disease (CVD), and women with preeclampsia appear to be at increased risk of future CVD. We hypothesized that these factors are detectable in asymptomatic postpartum women with a history of preeclampsia and may represent pathophysiological mechanisms bridging preeclampsia and future CVD. We measured fasting insulin, glucose, vascular endothelial growth factor, and its circulating inhibitor, soluble fms-like tyrosine kinase (sFlt-1) in 29 normotensive women with a history of preeclampsia and 32 women with prior normotensive pregnancies at 18.0 +/- 9.7 months postpartum. The homeostasis model of insulin resistance (HOMA(IR)) [(insulin [microunits per milliliter] x glucose [millimoles per liter])/22.5] was calculated. Compared with women with normal pregnancies, women with prior preeclampsia had significantly increased levels of sFlt-1 (41.6 +/- 6.7 vs. 30.4 +/- 10.2; P < 0.01) and median HOMA(IR) (2.8 vs. 1.9; P = 0.04). Membership in the upper quartile of either sFlt-1 or HOMA(IR) was associated with prior preeclampsia (odds ratio 5.7; 95% confidence interval 1.7, 20.0; P < 0.01), and all five women in the upper quartiles of both sFlt-1 and HOMA(IR) had a history of preeclampsia. Women with a history of preeclampsia demonstrate altered expression of angiogenesis-related proteins and increased HOMA(IR) more than 1 yr postpartum. These factors may contribute to their risk of future CVD.

Adult↗

PubMedDate not supplied

The many faces of HIV nephropathy: results of the disease and consequences of treatment.

Impaired renal function is a consequence of HIV infection, even without a defined AIDS syndrome. While collapsing focal and segmental glomerulosclerosis is the clinical entity that is associated most commonly with progressive disease, the spectrum of renal involvement in patients who are HIV positive is expanding. In addition, consequences of anti-retroviral therapy are well-documented in the literature. The current case illustrates an unusual primary renal pathology picture presumably related to his underlying HIV disease and compounded by the unexpected consequences of anti-retroviral therapy, noted long after discontinuation of the medication.

AIDS-Associated Nephropathy↗