Transplacental transfer of taurine, a ␤-amino acid essential for fetal and neonatal development, constitutes the primary source of taurine for the fetus. Placental transport of taurine is compromised in pregnancies complicated by intrauterine growth restriction, resulting in a reduced concentration of taurine in cord plasma. This could impact on fetal cellular metabolism as taurine represents the most abundant intracellular amino acid in many fetal cell types. In the present study, we have used pure isolates of fetal platelets and T lymphocytes from cord blood of placentas, from normal, term pregnancies, as fetal cell types to examine the cellular uptake mechanisms for taurine by the system ␤ transporter and have compared gene and protein expression for the taurine transporter protein (TAUT) in these two cell types. System ␤ activity in fetal platelets was 15-fold higher compared with fetal T lymphocytes (P Ͻ 0.005), mirroring greater TAUT mRNA expression in platelets than T lymphocytes (P Ͻ 0.005). Cell-specific differences in TAUT protein moieties were detected with a doublet of 75 and 80 kDa in fetal platelets compared with 114 and 120 kDa in fetal T lymphocytes, with relatively higher expression in platelets. We conclude that greater system ␤ activity in fetal platelets compared with T lymphocytes is the result of relatively greater TAUT mRNA and protein expression. This study represents the first characterization of amino acid transporters in fetal T lymphocytes. cord blood cells; amino acid; taurine transporter protein; system ␤ TAURINE (2-aminoethanesulfonic acid) is the most abundant free amino acid in several tissues, including the placenta and the cellular components of blood (9,21,38,41,46). It is a ␤-amino acid with the sulfonic acid group attached to the ␤-carbon atom and is not incorporated into proteins (14). The physiological functions of taurine are diverse, including bile and xenobiotic conjugation, regulation of neuronal excitability, membrane protection, antioxidation, detoxification, and osmoregulation (22,24,31). The nutritional requirements for taurine are met both by dietary sources and biosynthesis from cysteine and methionine (53). However, in the human fetus and the neonate, taurine is an essential amino acid, as biosynthetic capacity is almost negligible (51) due to the lack of cysteine sulfonic acid decarboxylase, which catalyses the rate-limiting step in taurine synthesis (4). Transplacental transfer of taurine from maternal blood therefore constitutes the primary source of fetal taurine.Taurine is transported across cell membranes, including those of the syncytiotrophoblast, the transporting epithelium of human placenta, by the system ␤-amino acid transport system which is specific for taurine and other ␤-amino acids such as ␤-alanine and hypotaurine (29,32,36). System ␤ is a highaffinity, low-capacity transport system that is Na ϩ -and Cl Ϫ -dependent (10) with a 2:1:1 Na ϩ :Cl Ϫ :taurine stoichiometry (39, 48). System ␤ activity has been demonstrated in many cell types and its ca...

This is a literature review for management of angiomyolipoma (AML), lymphangioleiomyomatosis (LAM) and tuberous sclerosis (TS) during pregnancy, prompted by a case of a 23-year-old woman who presented with generalised itching at 31 weeks' gestation and was found to have a large vascular retroperitoneal mass in the lower pole of the left kidney. Magnetic resonance imaging (MRI) was suggestive of angiomyolipoma with multiple large aneurysms and haemorrhage within the tumour. She was delivered at 38 weeks by elective caesarean section, to avoid the risk of rupture and bleeding from the aneurysms during labour. Further imaging, with MR angiogram, computed tomography (CT) of the abdomen and pelvis and high resolution CT (HRCT) of the chest, confirmed lymphangioleiomyomatosis with left AML. She had embolisation of the AML performed twice, 8 weeks apart after delivery and subsequently had a left nephrectomy.

Intrauterine growth restriction (IUGR) is associated with reduced activity of placental amino acid transport systems ␤ and A. Whether this phenotype is maintained in fetal cells outside the placenta is unknown. In IUGR, cord blood tumor necrosis factor (TNF)-␣ concentrations are raised, potentially influencing amino acid transport in fetal cells. We used fetal T lymphocytes as a model to study systems ␤ and A amino acid transporters in IUGR compared with normal pregnancy. We also studied the effect of TNF-␣ on amino acid transporter activity. In fetal lymphocytes from IUGR pregnancies, taurine transporter mRNA expression encoding system ␤ transporter was reduced, but there was no change in system ␤ activity. No significant differences were observed in system A mRNA expression (encoding SNAT1 and SNAT2) or system A activity between the two groups. After 24 or 48 h TNF-␣ treatment, fetal T lymphocytes from normal pregnancies showed no significant change in system A or system ␤ activity, although cell viability was compromised. This study represents the first characterization of amino acid transport in a fetal cell outside the placenta in IUGR. We conclude that the reduced amino acid transporter activity found in placenta in IUGR is not a feature of all fetal cells. (Pediatr Res 65: 51-56, 2009) I ntrauterine growth restriction (IUGR) occurs when a fetus fails to achieve its expected growth potential and may complicate approximately 5% of pregnancies (1). The shortand long-term consequences include perinatal morbidity with an increased risk of a "cerebral insult" and neurodevelopmental impairments in later childhood (2). In IUGR, there is a reduction in cord plasma concentration of amino acids including essential amino acids (3,4), underscored by a reduced activity of certain amino acid transport systems in the syncytiotrophoblast of human placenta (5).Amino acid transfer across the placenta is mediated by transporters in the maternal-facing microvillous plasma membrane (MVM) and fetal-facing basal plasma membrane (BM) of the syncytiotrophoblast (6). Plasma amino acid concentrations are higher in the fetus than in the mother, in keeping with active transport systems in MVM and BM. In IUGR, the activities of a range of amino acid transporters in MVM and BM are reduced (5). These include system A transporter in MVM (7-9), system L transporter in MVM and BM (10), system y ϩ L transporter in BM (10), and system ␤ transporter in MVM (11). Furthermore, stable isotope studies have shown that placental supply of leucine and phenylalanine exceeds fetal demand for protein synthesis by only a small amount suggesting a narrow safety margin for placental transfer of these essential amino acids (12). Thus, reduced amino acid placental transfer in IUGR has the potential to directly limit fetal growth (5,13).The basis for this decreased placental amino acid transport activity is not clearly understood. It may have a genetic basis or may be secondary to an alteration in the metabolic and/or endocrine milieu of the mother ...