Prenatal sonographic diagnosis of conjoined twins in the first trimester: two case reports

Conjoined twins are a rare occurrence. We present two cases of conjoined twins diagnosed by ultrasound examination at 8 and 13 weeks' gestation, respectively. These cases demonstrated the possibility of making an accurate diagnosis of conjoined twins and delineating the extent of organ sharing in the first trimester.

Gestational 'impaired glucose tolerance': should the cut-off be raised to 9 mmol l(-1)?

It has been suggested that the diagnostic criterion for the 2-h value of the 75 g oral glucose tolerance test in pregnancy be raised to 9 mmol l(-1). In order to determine whether patients with a 2-h value of between 8 and 8.9 mmol l(-1) should be classified as normal, we performed a retrospective study on patients with gestational diabetes mellitus treated with diet only who delivered within 1 year, and categorized them into three groups according to the 2-h value as follows: group A (8-8.9 mmol l(-1)), group B (9-10.9 mmol l(-1)), and group C (> or =11.0 mmol l(-1)). These groups were compared with a control group with normal oral glucose tolerance test results and who delivered within the same 1-year period. Group A patients were significantly different from the control group in maternal age, parity, fasting value in the oral glucose tolerance test, maternal body mass index, gestational age at delivery, incidence of large for dates infants, and placental weight, but were similar to group B for most of these parameters. Group C was significantly different from both the control group and group A for most of the above parameters. Our results suggest that the current World Health Organization criterion for the diagnosis of gestational diabetes mellitus should be maintained.

Limb reduction defects in fetuses with homozygous alpha-thalassaemia-1

Limb reduction defect is a rare event. Its exact pathogenesis is unknown. We retrospectively reviewed the outcome of 130 fetuses affected by homozygous alpha-thalassaemia-1 and found that 11 of them (8 per cent; 95 per cent confidence interval: 4-13 per cent) had terminal transverse limb reduction defects. Chromosome study was available in ten fetuses with limb defects and the results were normal. We postulate that the strong association between homozygous alpha-thalassaemia-1 and limb reduction is related to the hypoxic insult in early gestation. This may be the final common pathway in the pathogenesis of other forms of limb reduction defects.

Amelioration of mitochondrial function by a novel antioxidant U-101033E following traumatic brain injury in rats

In the present study, a severe traumatic brain injury (TBI) was produced over the right parietal cortex of rats using the controlled cortical impact injury (CCII) model. TBI perturbed calcium homeostasis and impaired electron transfer and energy coupling activities of forebrain mitochondria isolated from injured hemispheres with a maximal injury at 12-72 h. Efficacy of the blood-brain barrier penetrating antioxidant U-101033E on TBI-induced mitochondrial impairment was evaluated. In the dose-response experiment, two i.v. boluses (vehicle or 1-10 mg/kg of U-101033E) were administered at 5 min and 2h post-TBI. Forebrain mitochondria from each hemisphere were examined at 12 h post-injury. With respect to forebrain mitochondrial dysfunction, the drug showed a bell-shaped dose-response curve with an optimal dose of 3 mg/kg (n = 5, p < 0.05 vs. vehicle). In the time-course experiment, two i.v. boluses of 3 mg U-101033E/kg (the optimal dose) were given at 5 min and 2 h post-injury and forebrain mitochondria were examined at 6 h-14 days post-injury. U-101033E significantly restored electron transfer, energy coupling capacity, and Ca2+ transport capacity during 6 h to 14 days post-injury. Our data indicate that the antioxidant U-101033E administered post-injury at proper dosage can effectively restore TBI-induced mitochondrial dysfunction and support the contention that oxidative stress plays an important role in the pathogenesis of TBI.

Second-trimester maternal urinary gonadotrophin peptide screening for fetal Down syndrome in Asian women

Maternal urinary gonadotrophin peptide (UGP) was recently found to be elevated in second-trimester Down syndrome pregnancies. There is controversy about its screening efficacy. Data in the Asian population are scanty. We measured the UGP levels in 29 Down syndrome pregnancies and 297 controls and expressed them as a ratio of the urine creatinine concentration. Median UGP MOM was elevated to 3.44 (95 per cent confidence interval 1.99-5.13) in cases, compared with controls. UGP values were widely scattered in cases and controls with extensive overlap such that only 35 per cent of Down syndrome cases were expected to be detected at a 5 per cent false-positive rate. The data of the present study and previous reports show that there is a wide variability of gestation-specific UGP median values. UGP alone does not appear to be an effective screening marker for fetal Down syndrome.

Expression and function of Trk-C in favourable human neuroblastomas

Human neuroblastomas express the neurotrophin receptors trk-A and trk-B. Favourable outcome is associated with expression of trk-A, while unfavourable, MYCN amplified tumours express trk-B. In this study we examined the expression of trk-C in primary neuroblastoma tumour-derived cell lines. We found by Northern blot analysis that trk-C mRNA is expressed in 14 of 55 (25%) primary tumours. Trk-C was expressed in significantly more lower stage tumours (stage 1, 2, 4S) than higher stage tumours (stage 3, 4, P < 0.04). The expression of trk-C was correlated positively with survival and negatively correlated with MYCN amplification. We also studied the function of trk-C in transfected cell lines and found that NT-3 promotes both cell survival and differentiation. Our results suggest that trk-C is involved in the biology of favourable neuroblastomas.

Mitochondrial dysfunction after experimental and human brain injury and its possible reversal with a selective N-type calcium channel antagonist (SNX-111)

We have recently demonstrated in a rat model that traumatic brain injury induces perturbation of cellular calcium homeostasis with an overload of cytosolic calcium and excessive calcium adsorbed on the mitochondrial membrane, consequently the mitochondrial respiratory chain-linked oxidative phosphorylation was impaired. We report the effect of a selective N-type calcium channel blocker, SNX-111 on mitochondrial dysfunction induced by a controlled cortical impact. Intravenous administration of SNX-111 at varying times post injury was made. The concentration titration profile revealed SNX-111 at 4 mg kg-1 to be optimal, and the time window to be administration at 4 h post-injury, in line with that reported on the effect of SNX-111 in experimental stroke. Under optimal conditions, SNX-111 significantly improved the mitochondrial respiratory chain-linked functions, such as the electron transfer activities with both succinate and NAD-linked substrates, and the accompanied energy coupling capacities measured as respiratory control indices (RCI) and ATP synthesis (P/O ratio), and the energy linked Ca2+ transport. In order to assess the applicability of these data to the clinical setting, we have initiated studies with brain tissue which has to be resected during surgical treatment. Five patients suffered from brain trauma, one from intracranial hypertension due to stroke (noninfarcted tissue was taken), and one from epilepsy. Our data revealed that brain mitochondria derived from the patient with intracranial hypertension and the patient with epilepsy were tightly coupled with good respiratory rates with glutamate and malate as substrates, and high P/O ratios. The rates of respiration and ATP synthesis were severely impaired in the brain mitochondria isolated from traumatized patients. These results indicate that investigation of brain mitochondrial functions can be used as a measure for trauma-induced impairment of brain energy metabolism. The time window for the effect of SNX-111 in mitochondrial function and the (preliminary) similarity between mitochondrial dysfunction in experimental animals and humans make the drug appear to be well suited for clinical trials in severe head injury.

Early ultrasound prediction of pregnancies affected by homozygous alpha-thalassaemia-1

Homozygous alpha-thalassaemia-1 is conventionally diagnosed by invasive testing on all at-risk pregnancies. We evaluated the diagnostic efficacy of non-invasive abdominal ultrasonographic cardiothoracic ratio measurement in 62 pregnancies at 13-14 weeks and 75 pregnancies at 17-18 weeks. This performed better than placental thickness measurement. Using a cardiothoracic ratio cut-off level of > or = 0.5, 75 per cent of affected pregnancies were detected at 13-14 weeks and all cases were detected at 17-18 weeks. False-positive rates were 7 and 8 per cent, respectively. There was no false-positive diagnosis if the cardiothoracic ratio was > or = 0.53. With this approach, invasive procedures can be selectively performed and fewer pregnancies will be lost unnecessarily. The reduction in medical expenses is likely to be substantial.

Second-trimester hydrops fetalis in pregnancies affected by homozygous alpha-thalassaemia-1

Homozygous alpha-thalassaemia-1 is the commonest cause of hydrops fetalis in South-East Asia. Ultrasonographic features of hydrops fetalis were said to be evident only after 20 weeks of gestation. We studied 111 pregnancies at risk of homozygous alpha-thalassaemia-1 at 12-14 gestational weeks and 101 pregnancies at 17-18 weeks by abdominal ultrasound examination. Ultrasonographic features of hydrops fetalis were seen in 3 out of 44 pregnancies affected by homozygous alpha-thalassaemia-1 at 12-14 weeks [7 per cent; 95 per cent confidence interval (CI) 1-19 per cent] and in 7 out of 21 affected pregnancies at 17-18 weeks (33 per cent; 95 per cent CI 15-57 per cent). In conclusion, homozygous alpha-thalassaemia-1 can cause hydrops fetalis in the early second trimester. It should constitute one of the differential diagnoses in the work-up of second-trimester hydrops fetalis.

Placental weight to birthweight ratio is increased in mild gestational glucose intolerance

To determine if the placental weight to birthweight ratio (placental ratio) is increased in pregnancies complicated by diet-treated gestational impaired glucose tolerance (IGT) and diabetic (GDM) pregnancies, a retrospective case control study was performed on 478 singleton IGT/GDM pregnancies delivered in 1994 and compared with a control group that consisted of the next case with normal OGTT performed on the same day as each index case. The placental weight and ratio, and the placental ratio alone, were found to be significantly increased in the IGT and GDM groups respectively compared with the control group. Significant correlation was demonstrated between the placental ratio with OGTT 2-h value and maternal body mass index. Multiple regression analysis indicated that the OGTT 2-h value was the significant determinant for placental ratio. Our results showed that increased placental size and ratio were found in IGT/GDM pregnancies that required diet treatment only, and this increase was related to the degree of glucose intolerance as shown in the OGTT 2-h value.

Pro- and anti-oxidant activities of the mitochondrial respiratory chain: factors influencing NAD(P)H-induced lipid peroxidation

This paper is a study of factors influencing the rate of lipid peroxidation in beef heart submitochondrial particles induced by NAD(P)H via the NADH-ubiquinone oxidoreductase (Complex I) of the respiratory chain. In accordance with earlier observations, both NADH and NADPH initiated lipid peroxidation in the presence of ADP-Fe3+. The rate of the reaction, measured as oxygen consumption and formation of thiobarbituric acid reactive substances, was biphasic as a function of NADH concentration, reaching a maximum at low NADH concentrations and then declining. In contrast, the NADPH-initiated lipid peroxidation showed a monophasic concentration profile of hyperbolic character. Rotenone did not eliminate the biphasicity of the NADH-induced reaction, indicating that this was not due to an antioxidant effect of reduced ubiquinone at high NADH concentrations. This conclusion was further supported by the demonstration that extraction of ubiquinone from the particles did not relieve the inhibition of lipid peroxidation by high NADH concentrations. However rhein, another inhibitor of Complex I, eliminated the biphasicity, and even caused a substantial stimulation of the NADH-induced lipid peroxidation in the particles upon extraction of ubiquinone by pentane. No similar effect occurred in the case of NADPH-induced lipid peroxidation. Furthermore, rhein facilitated both NADH- and NADPH-induced lipid peroxidation even in the absence of added ADP-Fe3+, in a fashion similar to that earlier reported with succinate in the presence of theonyltrifluoroacetone. Based on these findings and measurements of the redox states of ubiquinone and cytochromes in the presence of KCN and NADH or NADPH, it is concluded that Complex I may distinguish between electron input from NADH and NADPH by differences in the site(s) of substrate binding and in the pathways and rates of NADH and NADPH oxidation.

Mitochondrial dysfunction and calcium perturbation induced by traumatic brain injury

Traumatic brain injury (TBI) is associated with primary and secondary injury. A thorough understanding of secondary injury will help to develop effective treatments and improve patient outcome. In this study, the GM model of controlled cortical impact injury (CCII) of Lighthall (1988) was used with modification to induce lateral TBI in rats. Forebrain mitochondria isolated from ipsilateral (IH) and contralateral (CH) hemispheres to impact showed a distinct difference. With glutamate + malate as substrates, mitochondria from the IH showed a significant decrease in State 3 respiratory rates, respiratory control indices (RCI), and P/O ratios. This decrease occurred as early as 1 h and persisted for at least 14 days following TBI. The State 3 respiratory rates, RCI, and P/O ratios could be restored to sham values by the addition of EGTA to the assay mixture. A significant amount of Ca2+ was found to be adsorbed to the mitochondria of both the IH and the CH with higher values seen in the IH. The rate of energy-linked Ca2+ transport in the IH was significantly decreased at 6 and 12 h. These data indicate that CCII-induced TBI perturbs cellular Ca2+ homeostasis and results in excessive Ca2+ adsorption to the mitochondrial membrane, which subsequently inhibits the respiratory chain-linked electron transfer and energy transduction.

Lipid peroxidation and changes in the ubiquinone content and the respiratory chain enzymes of submitochondrial particles

The relationship between, lipid peroxidation induced by ascorbate and adenosine ADP/Fe3+, and its effect on the respiratory chain activities of beef heart submitochondrial particles has been investigated. Lipid peroxidation, measured as thiobarbituric acid reactive substance formation, resulted in an inhibition of the NADH and succinate oxidase activities. Examination of several partial reactions of the respiratory chain revealed inactivation primarily of those involving endogenous ubiquinone, i.e., NADH- and succinate-ubiquinone1 and cytochrome c reductases. Ubiquinol-cytochrome c reductase, measured with reduced ubiquinone2 as electron donor, was unaffected. The amount of NADH- or succinate-reducible cytochrome b in the presence of cyanide was strongly decreased, but could be recovered by the addition of antimycin. There occurred a substantial decrease of the ubiquinone content in the course of lipid peroxidation, with a linear relationship between this decrease and the NADH and succinate oxidase activities. The results are consistent with the conclusion that the ubiquinone pool undergoes an oxidative modification during lipid peroxidation, to a form that can no longer function as a component of the respiratory chain. Lipid peroxidation also led to a partial inhibition of the succinate dehydrogenase and cytochrome c oxidase activities and a minor decrease of the cytochrome c and cytochrome a contents. Reduction of endogenous ubiquinone prevented lipid peroxidation as well as the concomitant modification of ubiquinone and inactivation of the respiratory chain. These observations suggest that the destruction of ubiquinone through lipid peroxidation is the primary cause of inactivation of the respiratory chain, and emphasize the antioxidant role of ubiquinol in preventing these effects. The possible implications of these findings for regulation of the cellular turnover of ubiquinone by the prevailing oxidative stress are discussed.

Expression of TrkA, TrkB and TrkC in human neuroblastomas

There is considerable interest in the role of the TRK family of neurotrophin receptors in regulating the survival, growth and differentiation of normal and neoplastic nerve cells. Indeed, there is increasing evidence that TRK genes play an important role in the biology and clinical behavior of neuroblastomas, tumors of the peripheral nervous system. Evidence from several independent studies suggests that high expression of TrkA is an indicator of favorable outcome, and there is an inverse correlation between TrkA expression and N-myc amplification. In addition, some primary neuroblastomas differentiate in vitro in the presence of NGF but die in its absence. We have evidence that coexpression of full-length TrkB and BDNF is associated with N-myc amplification and may represent an autocrine survival pathway. Conversely, truncated TrkB is expressed predominantly in differentiated tumors. Finally, Trk-C is expressed in favorable neuroblastomas, essentially all of which also express TrkA. In summary, the study of neurotrophin receptor expression and function in neuroblastomas may provide important insights into the role that these pathways play in the pathogenesis and clinical behavior of this tumor. Ultimately, these pathways may provide attractive targets for the development of therapy aimed at inducing differentiation or programmed cell death in these tumors.

Metabolism, uptake, and transepithelial transport of the stereoisomers of Val-Val-Val in the human intestinal cell line, Caco-2

PURPOSE

The purpose of this study was to determine the stereospecificity of the apical oligopeptide transporter(s) for the stereoisomers of Val-Val-Val and to determine whether the interaction of these molecules with this transporter(s) could be correlated with their cellular uptake and/or transepithelial transport.

METHODS

The interactions of these stereoisomers with this transporter(s) were evaluated by determining their ability to inhibit [3H]cephalexin uptake into Caco-2 cells. The metabolism of these stereoisomers was determined in a homogenate of Caco-2 cells and in the apical bathing solution over Caco-2 cell monolayers. The cellular uptake and transepithelial transport properties of these stereoisomers were studied using the Caco-2 cell monolayers.

RESULTS

The L-L-L tripeptide was totally degraded within 1 h in the Caco-2 cell homogenate and within 2 h when applied to the apical side of a Caco-2 cell monolayer. In contrast, 36.7 +/- 1.3% and 69.7 +/- 0.9% of L-Val-L-Val-D-Val remained after 2 h in the cell homogenate and in the apical bathing solution, respectively. The other six stereoisomers of Val-Val-Val were completely stable in the Caco-2 cell homogenate. Five of the stereoisomers (L-L-L, L-L-D, L-D-L, D-L-L, D-D-L) significantly inhibited the cellular uptake of [3H]cephalexin (91%, 62%, 14%, 45%, 16%, respectively). The other stereoisomers had no effect on the [3H]cephalexin uptake. When the cellular uptake of the stereoisomers was determined, the D-L-L and L-D-L tripeptides showed the highest intracellular concentrations (1.32 +/- 0.25 and 0.62 +/- 0.20 nmol/mg protein after a 2-h incubation, respectively). In contrast, the intracellular concentrations of the other stereoisomers were less than 0.1 nmol/mg protein. Moreover, the cellular uptake of the D-L-L and L-D-L tripeptides was inhibited by Gly-Pro by 82% and 68%, respectively, whereas Gly-Pro showed moderate to no inhibitory effect on the cellular uptake of the other stereoisomers. The permeability coefficients of the stereoisomers across the Caco-2 cell monolayers were very low (1.8 to 3.1 x 10(-7) cm/sec) and almost identical. Gly-Pro had no effect on their transepithelial transport.

CONCLUSIONS

These results suggest that the interaction of the Val-Val-Val stereoisomers with the apical oligopeptide transporter(s) could be a good predictor of their cellular uptake. However, since the major transepithelial transport mechanism of Val-Val-Val stereoisomers is passive diffusion via the paracellular route, the binding of these molecules to the oligopeptide transporter(s) is not a good predictor of their transepithelial transport. It appears that the stereochemical requirements for the transporter that mediates permeation of the peptide across the basolateral membrane may be different from the requirements for the apical transporter that mediates cellular uptake.

Detection of EBV in tumor tissue and peripheral blood by polymerase chain reaction in patients with nasopharyngeal carcinoma

Sixty-nine untreated patients with a pathologically verified nasopharyngeal carcinoma were selected for the study of detection of EBV in nasopharyngeal tumor and peripheral blood by polymerase chain reaction (PCR). Primers were directed to conserved regions of EBV genome encoding capsid protein gp 220 (Bam HI L region). A distinct 239 bp band of the PCR products indicated the presence of EBV. Results showed that EBV DNA was obtained in 91.3% of 69 NPC patients and 16.7% of 18 healthy individuals on nasopharyngeal tissue, and the difference was statistically significant between the above two groups. Nevertheless, no EBV DNA was verified from the mononuclear cells of the peripheral blood of the two groups. There was no relationship between the positive EBV DNA and the titer of serological markers. Meanwhile, the positive EBV DNA did not show any relationship with the histology type, tumor and nodal bulk, or even metastasis. Although a high positive rate of EBV DNA was detected in nasopharyngeal tumor of patients, additional environmental and genetic factors must still be considered.

A multicentre study to investigate the prevalence of abnormal carbohydrate metabolism in Chinese pregnant women

OBJECTIVES

To determine the prevalence of abnormal carbohydrate metabolism in Chinese pregnant women. To study the inter-relationship between maternal body habitus, maternal serum glucose and birth weight of the baby.

METHODS

Multicentre observational study involving 713 pregnant Chinese women, attending antenatal clinics in Beijing, Shanghai, Guangzhou and Hong Kong.

RESULTS AND CONCLUSION

The overall prevalence of abnormal glucose tolerance was 6.9%. The prevalence was 6.8%, 5.5%, 7.2% and 8.1% in Beijing, Shanghai, Guangzhou and Hong Kong, respectively. The differences among the centres did not reach statistical significance (p = 0.9). The mean ponderal index of women with abnormal glucose tolerance was significantly higher than that of women with normal glucose tolerance (15.2 vs 14.3, p < 0.01). The birth weight ratio of the babies was positively correlated with the maternal height (correlation coefficient 0.23, 95% C.I. 0.15-0.30), weight (0.32, 95% C.I. 0.25-0.39) and to a lesser extent, the fasting level of serum glucose (0.10, 95% C.I. 0.02-0.28) but not with the 2 hour level of serum glucose.

Metabolism, uptake, and transepithelial transport of the diastereomers of Val-Val in the human intestinal cell line, Caco-2

PURPOSE

The purpose of this study was to determine whether the binding of the diastereomers of Val-Val to the apical oligopeptide transporter(s) could be correlated with their cellular uptake and transepithelial transport.

METHODS

The Caco-2 cell culture system was used for all experiments. The binding of the diastereomers of Val-Val was evaluated by determining their ability to inhibit [3H]cephalexin uptake. The stability of the diastereomers was determined in a homogenate of Caco-2 cells and in the apical bathing solution over Caco-2 cell monolayers. The cellular uptake and transepithelial transport properties of the individual diastereomers were studied using Caco-2 cell monolayers.

RESULTS

10 mM concentrations of L-Val-L-Val, L-Val-D-Val, D-Val-L-Val and D-Val-D-Val inhibited cellular uptake of [3H]cephalexin (0.1 mM) by 92%, 37%, 70%, and 18%, respectively. When the cellular uptake of Val-Val diastereomers (1 mM) were evaluated, the intracellular concentrations of L-Val-D-Val and D-Val-L-Val were 15 and 50 times higher, respectively, than that of D-Val-D-Val. The cellular uptake of L-Val-D-Val and D-Val-L-Val was inhibited by Gly-Pro (10 mM) ( > 95%), whereas Gly-Pro had no effect on the cellular uptake of D-Val-D-Val. L-Val-L-Val was not detected in the Caco-2 cells, probably due to its metabolic lability. When the transepithelial transport of the Val-Val diastereomers (1 mM) was determined, L-Val-D-Val, D-Val-L-Val and D-Val-D-Val transport rates were similar. The transepithelial transport of L-Val-D-Val and D-Val-L-Val was inhibited by Gly-Pro (10 mM) 36% and 30%, respectively, while Gly-Pro inhibited carnosine (1 mM) transepithelial transport by 65%. Gly-Pro had no effect on the transepithelial transport of D-Val-D-Val.

CONCLUSIONS

These results suggest that the major transepithelial transport route of L-Val-D-Val, D-Val-L-Val and D-Val-D-Val is passive diffusion via the paracellular route. The binding of Val-Val diastereomers to the oligopeptide transporter(s) is a good predictor of their cellular uptake, however, the binding is not a good predictor of their transepithelial transport. It appears that the stereochemical requirements for the transporter that mediates efflux of the peptide across the basolateral membrane may be different from the requirements for the apical transporter that mediates cellular uptake.