Inter-twin hemoglobin difference at birth in uncomplicated monochorionic twins in relation to the size of the placental anastomoses.

OBJECTIVE: To evaluate the relation between Hb levels and the size of the placental anastomoses. METHODS: We performed a retrospective review of all uncomplicated MC twins delivered vaginally at our center from 2002 to 2017. Hb levels at birth and on day 2 were retrieved. All MC placentas were routinely injected with colored dye and high-resolution pictures were taken for computer-based analysis. We measured the size of arterio-arterial (AA) and veno-venous (VV) anastomoses as well as the total venous size, defined as the sum of the diameter of first generation of placental veins within 5 cm of each cord insertion. We assessed the relation between Hb levels and placental angioarchitecture. RESULTS: A total of 170 MC twin pairs were analyzed. Median Hb level in twin 1 was significantly lower than that in twin 2 both at birth (16.0 versus 17.4 g/dl, P = 0.02) and on day 2 (14.6 versus 18.1 g/dl, P = 0.000000188). Inter-twin Hb difference on day 2 was positively correlated with the size of AA anastomoses (Spearman r = 0.25, 95% CI 0.04-0.43, P = 0.0161). The diameter of AA anastomoses was positively related to the total size of veins connecting to AA anastomoses in the placental territory of twin 2 (Spearman r = 0.55, 95% CI 0.41-0.66, P = 0.0001). DISCUSSION: MC twins with larger AA anastomoses have higher Hb differences at birth. Higher Hb levels in second born twins may partly be due to increased placento-fetal transfusion through larger placental vessels.

Hypoalbuminemia in donors with twin anemia-polycythemia sequence: a matched case-control study.

OBJECTIVE: To determine the differences in albumin levels between donors and recipients with twin anemia-polycythemia sequence (TAPS). METHODS: We included all consecutive monochorionic twins with TAPS with double survivors. Each twin pair was matched for gestational age at birth with 2 control monochorionic twin pairs unaffected by TAPS or twin-twin transfusion syndrome. We measured levels of albumin, total protein, and hemoglobin on the first day of life in donors and recipients (TAPS group) and the control group. RESULTS: A total of 25 TAPS twin pairs and 50 control twin pairs were included in the study. The median gestational age at birth was 32 weeks in both groups. In the TAPS group, median levels (IQR) of albumin in donor twins were significantly lower than in recipient twins, i.e. 28.0 g/l (24.0-32.0) versus 32.0 g/l (30.0-34.5) (p = 0.008). Median levels (IQR) of total protein in donor twins were also lower than in recipients, i.e. 44.0 g/l (36.5-49.0) versus 49.0 g/l (46.5-51.0), respectively (p = 0.004). The median (IQR) intertwin albumin difference was significantly higher in the TAPS group than in the control group, i.e. 4.0 g/l (2.5-10.5) versus 2.0 g/l (1.0-4.0) (p = 0.003). The rate of hypoalbuminemia (<20 g/l) and hypoproteinemia (<40 g/l) in donor twins with TAPS was 20% (5/25) and 32% (8/25). CONCLUSIONS: In addition to lower hemoglobin levels, donor twins with TAPS also have significantly lower albumin and total protein levels compared to recipient twins.

Hypoalbuminemia in donors with twin-twin transfusion syndrome.

OBJECTIVE: To estimate the differences in albumin levels between donors and recipients with twin-twin transfusion syndrome (TTTS). METHODS: We performed a matched case-control study including twin pairs with TTTS treated conservatively (conservative group) or with fetoscopic laser surgery (laser group) and analyzed the albumin levels at birth in donor and recipient twins. RESULTS: We included 18 twin pairs in the conservative group and 36 control twin pairs (laser group), matched for gestational age at birth. Median albumin levels in donor twins in the conservative group were significantly lower than in recipient twins, 25.0 versus 33.0 g/l, respectively (p = 0.001). In the laser group, albumin levels in donors and recipients were similar, 32.0 versus 32.0 g/l, respectively (p = 0.633). Hypoalbuminemia (albumin level <20 g/l) occurred in 22% (4/18) of donor twins in the conservative group. CONCLUSIONS: Hypoalbuminemia occurs frequently in donor twins with TTTS treated conservatively. In TTTS treated with laser, donor twins have similar and normal albumin levels compared to recipients, confirming a successfully performed fetoscopic laser procedure.

Genotypic Approaches to Therapy in Children (GATC): using information technology to improve drug safety.

Adverse drug reactions (ADRs) are a major cause of morbidity and mortality in children. Current models of ADR surveillance have repeatedly demonstrated little pragmatic value to practicing clinicians. ADR reporting rates in the US and Canada suggest that only 5% of ADRs are reported. The Genotypic Approaches to Therapy in Children (GATC) network was established to identify and solve drug safety problems in paediatrics. We hypothesized that genetic polymorphisms underlie a significant portion of concentration-dependent ADRs in children. Our objective was to establish an ADR active surveillance network in paediatric hospitals across Canada. Surveillance clinicians evaluate clinical information from ADR cases and drug-matched controls, and collected DNA samples from all patients. The surveillance network will enable the identification of predictive genomic-markers for ADRs. With this knowledge, children at risk can be identified before therapy is initiated and enable personalized adjustments to therapy based on genetic make-up.

Bio-inspired synthetic receptor molecules towards mimicry of vancomycin.

A 512-member library of bio-inspired synthetic receptor molecules was prepared featuring a triazacyclophane scaffold. The purpose of this scaffold was to orient three (identical) peptide 'binding arms' in order to mimic an antibiotic binding cavity as is present in the vancomycin antibiotics. The library was screened with D-Ala-D-Ala and D-Ala-D-Lac containing ligands, which are present in the cell wall precursors of pathogenic bacteria. Screening and validation led to identification of a synthetic receptor capable of binding these ligands.

[Inhibition of carotenoid synthesis during nitrogen deficiency]. / Die Hemmung der Carotinoidsynthese im Stickstoffmangel.

The ability to synthesize carotenoids during normal or strongly reduced nitrogen supply was tested in a higher plant (Hordeum vulgare L.) and in a green alga (Scenedesmus obliquus). Though carotenoids are nitrogenfree, their synthesis is strongly inhibited during nitrogen deficiency. The formation of secondary carotenoids, which apparently proceeds at the expense of the primary carotenoid components, occurs in Scenedesmus but not in Hordeum plants. It is concluded that the dimerisation of geranly-geranyl-pyrophosphate is the limiting step in the carotenoid synthesis during nitrogen deficiency. The synthesis of prenyl chains is less affected by nitrogen deficiency.