Placental volume measured by three-dimensional ultrasound in the prediction of fetal alpha(0)-thalassemia: a preliminary report

OBJECTIVE

To evaluate the use of placental volume measured by three-dimensional (3D) ultrasound in predicting fetal homozygous alpha(0)-thalassemia (Hb-Bart's disease).

METHODS

From June 2002 to May 2004 singleton pregnancies at risk of alpha(0)-thalassemia and normal controls were studied prospectively at 9-12 weeks of gestation. Affected fetuses were suspected to have alpha(0)-thalassemia by two-dimensional (2D) ultrasound and confirmed by DNA analysis. Placental volume was measured on 3D ultrasound by a multiplanar technique. Intra- and interobserver agreement of measurements was assessed. The placental volume/crown-rump length quotient of the affected fetuses was compared with that of normal fetuses.

RESULTS

The final study group comprised 105 pregnancies; 43 were at risk of alpha(0)-thalassemia and 62 were normal controls. Eleven (10.5%) fetuses were affected by alpha(0)-thalassemia, all from the at-risk group, and the others were normal. Intra- and interobserver agreement of volume measurement by 3D ultrasound was relatively poor; this was reflected in the wide limits of agreement, which ranged from -10.82 to 40.86 mL. The mean +/- SD placental volume/crown-rump length quotient in affected pregnancies was larger than that in unaffected pregnancies (1.37 +/- 0.65 vs. 1.13 +/- 0.39), but this difference was not significant (P > 0.05).

CONCLUSIONS

Assessment of placental volume by 3D ultrasound does not seem to be superior to 2D ultrasound in the first-trimester prediction of alpha(0)-thalassemia.

A new strategy for prenatal diagnosis of homozygous alpha(0)-thalassemia

OBJECTIVES

We have shown previously that ultrasound examination performed by one experienced operator can be useful to exclude homozygous alpha(0)-thalassemia in a tertiary referral center. This study aimed to determine whether the technique was still applicable when performed by several operators and in different centers.

METHODS

At the Maternal and Neonatal Hospital of Guangzhou (MNH) and Tsan Yuk Hospital of Hong Kong (TYH), women at risk of homozygous alpha(0)-thalassemia were given the option of a non-invasive approach (using serial ultrasound examinations at 12-15, 16-20 and 25-30 weeks' gestation) to exclude an affected pregnancy. The fetal cardiothoracic ratio (CTR) was measured at each of these examinations and the placental thickness was measured at 12-15 weeks' gestation. The operators of MNH received training on the ultrasound examination techniques at TYH and the quality of the subsequent ultrasound examinations was checked regularly. The final diagnosis of homozygous alpha(0)-thalassemia was confirmed using an invasive test.

RESULTS

Of 832 at-risk pregnancies studied in the two hospitals, 168 (20.2%) were affected. The overall sensitivity and specificity of the non-invasive approach was 100% and 95.6%, respectively. At MNH, the need for an invasive test was reduced by 80.8%, and all the affected pregnancies were diagnosed before 24 weeks' gestation. The results achieved at MNH were comparable with those at TYH. The at-risk pregnancies including the affected ones presented at a more advanced gestational age at MNH. At each hospital, one affected pregnancy was missed at the 12-week scan but this was subsequently detected at the 15-18-week scan.

CONCLUSIONS

This non-invasive approach to exclude homozygous alpha(0)-thalassemia can be applicable when it is performed by several operators and in different centers.

Full karyotyping, rapid aneuploidy diagnosis or both when invasive prenatal testing is performed for diagnosis of thalassaemia?

A retrospective study was performed to compare the detection rate of chromosomal abnormalities by different approaches of full karyotyping, rapid aneuploidy diagnosis (RAD) or both when invasive prenatal testing is performed for diagnosis of thalassaemia. The karyotype results of 1120 prenatal samples obtained from thalassaemia couples from January 1985 to December 2002 in a referral centre for prenatal diagnosis were studied. The detection rate of chromosomal abnormalities by four different approaches were compared: (i) karyotyping for all samples; (ii) RAD (21,18,13,X,Y) for all samples; (iii) RAD for all samples + karyotyping for cases with ultrasound abnormalities; and (iv) RAD (21,18,13) for all + RAD (X,Y) for cases with ultrasound abnormalities consistent with Turner syndrome + karyotyping for cases with ultrasound abnormalities. Normal karyotypes were found in 1103 samples (98.5%). There were 17 cases (1.5%) of chromosomal abnormalities: four cases (0.36%) were clinically significant, eight cases (0.7%) were of borderline clinical significance and five cases (0.44%) were not confirmed by subsequent prenatal or postnatal tests. The incidences of autosomal (7/1120 = 0.63%) and sex chromosomal (5/1120 = 0.45%) abnormalities were not higher than those (0.41 and 0.22%, respectively) from newborn surveys (Hook and Hamerton, 1977) (P = 0.398 and 0.216, respectively). Approach 1 would detect all 17 chromosomal abnormalities. Approach 2 would detect three of four clinically significant chromosomal abnormalities but not detect six of eight chromosomal abnormalities of borderline clinical significance and three of five chromosomal abnormalities not confirmed by subsequent prenatal or postnatal tests. Approach 3, in addition, would be able to detect all four clinically significant chromosomal abnormalities. Approach 4 would detect all four clinically significant chromosomal abnormalities but would not detect seven of eight chromosomal abnormalities of borderline clinical significance and four of five chromosomal abnormalities not confirmed by subsequent prenatal or postnatal tests. RAD (21,18,13) for all + RAD (X,Y) for cases with ultrasound abnormalities consistent with Turner syndrome + karyotyping for cases with ultrasound abnormalities seemed to be the best approach for the detection of chromosomal abnormalities when invasive prenatal testing is performed for diagnosis of thalassaemia.

Three-dimensional extended imaging: a new display modality for three-dimensional ultrasound examination

OBJECTIVE

To describe Three-Dimensional eXtended Imaging (3DXI) as a new display modality for three-dimensional (3D) ultrasound examination of the fetus.

METHODS

The spine, palate, heart and brain were evaluated using 3D ultrasound examination at a mean gestational age of 22 weeks in 35, 31, 32 and 31 fetuses, respectively. The volume data captured were analyzed using the conventional orthogonal display mode (ODM), as well as the 3DXI, which includes the Multi-Slice View (MSV) mode and the Oblique View (OBV) mode. The MSV mode allows simultaneous display of multiple sequential parallel planes while the OBV mode allows examination of a non-standard straight or curved plane.

RESULTS

The MSV mode allowed a simultaneous display of multiple sequential parallel planes of the fetal structures, but we found some uncertainty if an isolated image in one of the multi-slice images represented the exact level of a fetal structure. The MSV mode was advantageous in one of the six cases of facial cleft by allowing the simultaneous display of bilateral clefts that were located in two different axial planes. The multi-slice images were helpful in making the diagnosis in one case of holoprosencephaly. The OBV mode allowed examination of the coronal plane across the curvature of the spine, and the 'in-plane' view of the interventricular septum in a non-gated study.

CONCLUSION

The 3DXI can display the volume data in a different manner from that which usually results from the use of more conventional ODM, and provide additional information over conventional two-dimensional sonography.

The use of fetal Doppler cerebroplacental blood flow and amniotic fluid volume measurement in the surveillance of postdated pregnancies

BACKGROUND

This prospective observational study aims at determining the distribution of fetal cerebro-placental Doppler indices and amniotic fluid volume in a homogenous group of uncomplicated postdated pregnancies at 41 weeks. The correlation with incidence of passage of thick meconium-stained liquor in labor was analyzed to decide which parameter would be useful in the surveillance of postdated pregnancies.

METHODS

The amniotic fluid volume, middle cerebral artery pulsatility index, umbilical artery pulsatility index, and cerebroplacental ratio were measured and distribution determined in 118 well-dated singleton pregnancies admitted for routine induction of labor at 41 weeks. The 10th centile and the 90th centile in each Doppler parameter and amniotic fluid volume were chosen to divide each parameter into three centile groups. The prevalence of thick meconium-stained liquor in labor in different Doppler and amniotic fluid volume centile groups was compared using Chi-square test for trend with P < 0.05 taken as statistically significant.

RESULTS

The prevalence of thick meconium-stained liquor in labor was significantly inversely correlated with the middle cerebral artery pulsatility index (P = 0.008), with significant difference across different middle cerebral artery pulsatility index centile groups (P = 0.02). There was no significant difference in the prevalence of thick meconium-stained liquor in labor or oligohydramnios across different umbilical artery pulsatility index centile groups. Neither was there significant difference in the prevalence of thick meconium-stained liquor in labor and oligohydramnios across different cerebroplacental ratio and amniotic fluid volume centile groups. Logistic regression using the 10th centile of middle cerebral artery pulsatility index confirmed that it was a significant independent predicting factor for risk of thick meconium-stained liquor in labor with adjusted odds ratio (95th CI) of 6.14 (1.6-24.1).

CONCLUSION

Middle cerebral artery pulsatility index is better than amniotic fluid volume or umbilical artery pulsatility index in predicting the risk of thick meconium-stained liquor in labor in uncomplicated postdated pregnancy at 41 weeks.

Relationship between cerebroplacental Doppler ratio and birth weight in postdates pregnancies

OBJECTIVES

To explore the relationship between cerebroplacental Doppler impedance index and birth weight in postdates pregnancies, and to evaluate the use of a combination of Doppler parameters and ultrasound biometry in the prediction of large-for-gestational age (LGA) fetuses at 41 weeks of gestation.

METHODS

The pulsatility indices of the umbilical (UA-PI) and middle cerebral (MCA-PI) arteries, the cerebroplacental pulsatility index ratio (CPR) and the estimated fetal weight (EFW) were obtained in a cohort of 181 ultrasound-dated pregnancies at 41 weeks' gestation, 2 days before induction of delivery. A regression equation was established and the correlation between umbilical artery impedance and different birth-weight centile groups was determined. A receiver-operating characteristics (ROC) curve was used to compare prediction of LGA fetuses using biometry alone with that using biometry and UA-PI.

RESULTS

UA-PI was inversely related to EFW (Spearson's correlation coefficient rho = -0.28, P < 0.001). Logistic regression showed an independent contribution of UA-PI to the birth-weight estimation (birth weight = 1356.8 - 232.0 x UA-PI + 0.65 x EFW). On ROC curve analysis, the prediction of LGA with the regression equation was comparable to that using ultrasound biometry alone.

CONCLUSION

UA-PI was inversely correlated to EFW, but the combination of ultrasound biometry and UA-PI compared with biometry alone showed similar prediction of LGA fetuses in postdates pregnancies. Further prospective trials on larger populations or groups with a higher prevalence of LGA fetuses would be needed to validate the use of the new formula.

Cost-effectiveness of prenatal screening for thalassaemia in Hong Kong

OBJECTIVES

To determine the cost effectiveness of a universal prenatal screening program for alpha- and beta-thalassaemia.

METHODS

We retrospectively reviewed our program from 1998 to 2002, and calculated the direct and indirect costs of various components.

RESULTS

18,936 women were screened at our prenatal clinic and 153 couples were subsequently referred to our Prenatal Diagnostic Centre for counselling and further investigations. In addition, there were 238 tertiary referrals and 157 self-referrals. After investigations, 84 fetuses were at risk of beta-thalassaemia major/beta-E thalassaemia, 19 of them were affected and 18 were aborted. The total expenditure on our program (HK 10.0 million dollars) would be less than the postnatal service costs (HK 40.4 million dollars) for 18beta-thalassaemia major fetuses if they were born. Of 361 women at risk of carrying a homozygous alpha0-thalassaemia fetus, 311 (86.2%) opted for the indirect approach (using serial ultrasound examinations to exclude Hb Bart's disease), and 76 (24.5%) subsequently underwent an invasive test for a definitive diagnosis. The sensitivity and false positive rate of this indirect approach was 100.0% and 2.9% respectively.

CONCLUSION

It is cost effective to run a universal prenatal screening program in an area where both beta-thalassaemia and alpha-thalassaemia are prevalent. The indirect approach can effectively avoid an invasive test in unaffected pregnancies.

Simple non-invasive prenatal detection of Hb Bart's disease by analysis of fetal erythrocytes in maternal blood

OBJECTIVE

To investigate a simple non-invasive technique for early detection of Hemoglobin (Hb) Bart's disease.

METHOD

Maternal blood smears from 8 known Hb Bart's pregnancies and 40 at-risk pregnancies were investigated. Maternal peripheral blood smears were stained with fluorescence-labeled monoclonal antibodies against alpha- and embryonic zeta-globin chains.

RESULTS

Fetal nonnucleated red blood cells, stained with anti-zeta but not with anti-alpha globin antibodies were found in 15 out of 16 affected pregnancies but were not detected in 23 out of 24 unaffected pregnancies.

CONCLUSION

Results showed that non-invasive immunofluorescence staining of maternal blood is a feasible approach for screening Hb Bart's disease before ultrasound manifestation in affected pregnancies.

Doppler study of the umbilical and fetal middle cerebral arteries in women with gestational diabetes mellitus

OBJECTIVE

To investigate the correlation between Doppler parameters in the umbilical and fetal middle cerebral arteries and pregnancy outcome in women with gestational diabetes mellitus (GDM).

METHODS

A prospective study was performed on 169 singleton GDM pregnancies in a university teaching hospital from January to December 2002. Umbilical artery (UA) pulsatility index (PI) and middle cerebral artery (MCA) PI and peak systolic velocity (Vmax) were measured every 4 weeks until delivery from the time of diagnosis of GDM. The pregnancy outcome was obtained from the hospital database. Using linear or quadratic regression, lines of best fit were drawn to compare the Doppler measurements between the two groups with normal and abnormal pregnancy outcomes.

RESULTS

One hundred and thirty-eight women with known pregnancy outcome completed the study. A total of 305 Doppler examinations were performed with one to four examinations for each woman. Thirty-eight women (27.5%) had one or more abnormal pregnancy outcomes: placental abruption, pre-eclampsia, preterm delivery, small-for-gestational age (SGA) infants, low Apgar scores, neonatal jaundice requiring treatment, sepsis, birth trauma, meconium aspiration syndrome, respiratory and neurological complications. There was extensive overlap of the UA-PI, MCA-PI and MCA-Vmax measurements between the two groups.

CONCLUSION

A Doppler study of the UA-PI, MCA-PI and MCA-Vmax was not useful in the prediction of abnormal pregnancy outcome in GDM.

Randomised trial comparing an interactive multimedia decision aid with a leaflet and a video to give information about prenatal screening for Down syndrome

OBJECTIVES

(1)To compare an interactive multimedia decision aid (IMDA) with a leaflet and a video to give information about prenatal screening for Down syndrome and (2) to determine the women's acceptance of IMDA.

METHODS

Two hundred and one women were recruited from the prenatal clinic of a university teaching hospital and randomised into the intervention group (IMDA, video, and information leaflet) or the control group (video and information leaflet).

RESULTS

There were no significant differences in the initial decision for and the final uptake of the prenatal screening test between the control and intervention groups. The proportion of women who were undecided was less than 10% in both groups. Of the women in the intervention group, 86.6% and 78.9% agreed that IMDA was user-friendly and acceptable, respectively. Significantly more women aged < 35 (88.1%) accepted IMDA than women aged > or = 35 (68.3%) (P = 0.030), but the logistic regression analysis did not confirm this finding after adjusting for other factors (computer knowledge and usage of computer).

CONCLUSION

The use of IMDA did not affect the women's overall uptake rate of the prenatal screening test for Down syndrome. More women less than 35 years accepted IMDA probably because they used computer more frequently and had more computer knowledge.

A pilot-randomized comparison of sublingual misoprostol with syntometrine on the blood loss in third stage of labor

BACKGROUND

To compare sublingual misoprostol with intravenous syntometrine use during third stage of labor by measuring the blood loss.

METHODS

Sixty women were randomized to receive either 600 micro g misoprostol sublingually or 1 ml syntometrine intravenously during the third stage of labor after spontaneous vaginal delivery. For those with risk factors of postpartum hemorrhage such as medical induction or augmentation of labor, previous third stage complications were excluded. The blood loss in labor was measured by the alkaline-hematin method, and differences in hemoglobin before and after delivery were compared.

RESULTS

There was no significant difference in the median measured blood loss between the misoprostol group and the syntometrine group (280 versus 226 ml, p = 0.45). The change in hemoglobin was comparable between the two groups. There were more women in the misoprostol group who required additional oxytocics, but the difference was not statistically significant. A major complication occurred in one patient in the misoprostol group with blood loss in excess of 1000 ml. The incidence of side effects such as shivering and pyrexia in women receiving misoprostol was significantly higher than that in the syntometrine group.

CONCLUSION

The use of sublingual misoprostol or intravenous syntometrine in spontaneous vaginal delivery resulted in a comparable amount of blood loss. Transient side effect such as fever and shivering which resolved within a day occurred more frequent to those who received sublingual misoprostol.

Increase of lipid peroxidation by cisplatin in WI38 cells but not in SV40-transformed WI38 cells

Cisplatin (CPT) is an effective anticancer drug that causes cumulative toxicity to normal tissues. It has been suggested that CPT damages normal cells by causing oxidative stress, but it is not known whether it can induce similar oxidative damage to tumor cells. In this study, by using normal human lung fibroblast (W138) cells and SV40-transformed WI38 (VA13) cells as a model, we compared the effect of CPT on cytotoxicity, apoptosis, lipid peroxidation, and mitochondrial gene expression, which could be regulated by oxidative stress, between normal and tumor cells. CPT induced greater growth inhibition and percentage of apoptotic cells in VA13 cells. However, levels of esterified F(2)-isoprostanes and 4-hydroxy-2-nonenal, two specific products of lipid peroxidation, were increased by CPT in WI38 cells, but not in VA13 cells. Furthermore, the transcript level of mitochondrial 12S rRNA was augmented by CPT in both cells, but to a higher degree in WI38 cells. The data suggest a correlation between lipid peroxidation and cytotoxicity or increased mitochondrial transcript levels in WI38 cells but not in VA13 cells. The results also indicate an altered response of oxidative damage and mitochondrial gene regulation to CPT in the transformed phenotype of WI38 cells.

Successful outcome after serial amnioreductions in triplet fetofetal transfusion syndrome

BACKGROUND

Triplet fetofetal transfusion is an extremely rare complication with high perinatal mortality. Its rarity does not allow any prospective randomized study on various interventional methods to be conducted.

CASE

We report one case of triplet fetofetal transfusion syndrome with survival of all three fetuses. Two were donor fetuses, and one was the recipient fetus. Serial amnioreductions were performed at 22, 24, and 26 weeks' gestation to relieve symptomatic polyhydramnios. Premature rupture of membranes occurred at 27 weeks and cesarean delivery was performed. All three babies were discharged home by 4 months of age, and all had normal neurological development when assessed at 6 months of age.

CONCLUSION

The option of serial amnioreduction, with the anticipation and preparation for delivery at around 28 weeks, should be seriously considered when triplet fetofetal transfusion syndrome is encountered.

Unexpected reduction in the incidence of birth trauma and birth asphyxia related to instrumental deliveries during the study period: was this the Hawthorne effect?

OBJECTIVE

The study was originally designed to identify the risk factors that could predict those difficult instrumental deliveries resulting in birth trauma and birth asphyxia.

DESIGN

A prospective study on all singleton deliveries in cephalic presentation with an attempt of instrumental delivery over a 12-month period (13 March 2000 to 12 March 2001).

SETTING

A local teaching hospital.

SAMPLE

Six hundred and seventy deliveries.

METHODS

A codesheet was designed to record the demographic data, characteristics of first and second stages of labour and neonatal outcome. In particular, the doctor had to enter the pelvic examination findings before the attempt of instrumental delivery.

MAIN OUTCOME MEASURES

Birth trauma and birth asphyxia.

RESULTS

There was a significant reduction in the incidence of birth trauma and birth asphyxia related to instrumental deliveries during the study period (0.6%) when compared with that (2.8%) in the pre-study period (1998 and 1999) (RR 0.27, 95% CI 0.11-0.70). There was more trial of instrumental deliveries in the operating theatre although this was not statistically significant (RR 1.19, 95% CI 0.88-1.60). The instrumental delivery rate decreased during the study period (RR 0.88, 95% CI 0.82-0.94). The caesarean section rate for no progress of labour, the incidence of direct second stage caesarean section and the incidence of failed instrumental delivery did not increase during the study period.

CONCLUSIONS

Apart from the merits of regular audit exercise and increasing experience of the staff, the Hawthorne effect might be the major contributing factor in the reduction of birth trauma and birth asphyxia related to instrumental deliveries during the study period.

Factors affecting outcomes of prenatally-diagnosed tumours

OBJECTIVE

The outcomes of prenatally-diagnosed tumours affect obstetrical management and parental decisions. The present study reviews the factors affecting outcomes for fetuses with prenatally-diagnosed tumours.

METHODS

Medical records of all fetuses referred to our institutions with antenatally-diagnosed tumours were reviewed for the type and location of the tumours, results of treatment and/or causes of death.

RESULTS

From January 1994 to May 2001, there were 15 fetuses with antenatally- diagnosed tumours: mesoblastic nephroma (MN) (n=2); neuroblastoma (NB) (n=2); cystic hygroma (CH) (n=3); intracranial germ cell tumour (IGCT) (n=2); sacrococcygeal teratoma (SCT) (n=3) and haemangioma (liver, n=2; limb, n=1). One mother had termination of pregnancy for her fetal SCT. Three mothers had Caesarean section for large fetal heads (CH, n=2; IGCT, n=1). Three fetuses died; two with IGCT and one with SCT, who died of heart failure. Two newborns with CH needed emergency intubation and, later, one of them had tracheostomy. One baby had cardiac failure resulting from a lower limb haemangioma and needed drug therapy. All solid tumours (MN, NB, SCT) of the live births had no recurrence after surgery with or without adjuvant chemotherapy.

CONCLUSION

Prenatally-diagnosed tumours without any other associated abnormality cause morbidity and mortality because of their location and vascularity. Solid tumours are relatively benign.

Universal antenatal human immunodeficiency virus testing in Hong Kong: consensus statement

Following the recommendations of the Advisory Council on AIDS, Hong Kong, the Hospital Authority announced plans to introduce universal antenatal screening for human immunodeficiency virus infection and hence, a consensus conference was held to discuss strategies for implementing such screening in Hong Kong. This paper reports the discussions of the consensus conference. The consensus meeting group consisted of 15 clinicians and scientists from Hong Kong, Macau, and Thailand. Seven commonly asked questions concerning mother-to-child transmission of human immunodeficiency virus were selected for discussion by the participating panellists. Information on the laboratory diagnosis of human immunodeficiency virus infection and the efficacy of preventive measures in reducing mother-to-child transmission of human immunodeficiency virus were reviewed. Data from local studies was also presented and discussed. The timing, potential problems, and cost issues involved in testing all pregnant women in Hong Kong for human immunodeficiency virus were then considered.

Appearance of shortened Bcl-2 and Bax proteins and lack of evidence for apoptosis in rat forebrain after severe experimental traumatic brain injury

To investigate whether apoptosis plays a role in traumatic brain injury (TBI), we examined the expression of Bcl-2 and Bax proteins and the release of mitochondrial cytochrome c in rat brains using Western blot analysis. Bcl-2 at the predicted 26 kDa was not detected in controls and TBI groups. However, at 1 h post-TBI, a shortened Bcl-2 protein with a molecular size of approximately 14.5 kDa was detected in the injured hemisphere (R). At 4 and 12 h post TBI, an additional bcl-2 band ( approximately 10 kDa) was detected in R. Both bands disappeared at 14 days post-injury. The predicted 21-kDa band of Bax was detected in both controls and TBI animals. In addition, two shortened Bax proteins ( approximately 18 kDa) were detected after TBI. The time course of appearance was similar to that of Bcl-2 described above. In the present study, neither cytochrome c release from mitochondria nor DNA fragmentation was detected in the forebrains of sham and TBI groups. Treatment of animals with an antioxidant N-acetylcysteine administered ip greatly diminished the levels of shortened Bcl-2 and Bax proteins. These findings suggest that the induction of shortened Bcl-2 and Bax proteins in rat brains may be associated with reactive oxygen species generated after TBI.

The effect of fetal gender on nuchal translucency at 10-14 weeks of gestation

Recent data have suggested that fetal nuchal translucency (NT) is affected by fetal gender. We investigated the size of this effect in 12 189 unselected pregnancies with known normal outcomes that had undergone NT measurements between 10 and 14 weeks of gestation. NT increased with gestation and was converted to multiples of the median (MoM) for the gestational day. The median NT MoM (95% CI) for female fetuses was 0.98 (0.97-0.99). This was significantly lower than that of the male fetuses (1.03; range 1.02-1.04) (p<0.0005; Wilcoxon rank-sum test). The gender difference was not observed at 10 weeks but was observed from 11 weeks onwards. There is no obvious explanation for the above findings.

In vivo magnetic resonance (MR) study of fatty liver: importance of intracellular ultrastructural alteration for MR tissue parameters change

Fatty liver is thought to have a shorter T1 relaxation time than normal liver tissue, due to the accumulation of triglyceride. Previous studies regarding T1 and T2 relaxation times, however, show widely different results. In order to elucidate the mechanism responsible for the changes and diversity of relaxation times in fatty liver, we created two animal models in 14 rabbits, one acute form (N = 6) and the other chronic form (N = 8). Four rabbits were taken as a control group. Tissue relaxation times and the magnetization transfer (MT) effect of the liver tissue in these two models were measured. The results were correlated with biochemical analysis of water and fat content and histological examination, including findings in light microscopy and electron microscopy. Although the fatty ratio in both forms of fatty liver was similar, their tissue relaxation rate and MT effect were significantly different. The acute form showed prolongation of both T1 and T2 relaxation times (512 +/- 51 msec vs. 710 +/- 95 msec and 39 +/- 1.8 msec vs. 48 +/- 3.7 msec, respectively) and a decrease of the MT effect (50 +/- 5.1% vs. 38 +/- 6.3%), compared to those of the control group and preinduction liver. The chronic form showed shorter T1 and T2 values (526 +/- 36 msec vs. 406 +/- 56 msec and 36 +/- 1.6 msec vs. 33 +/- 2.3 msec, respectively) and a stronger MT effect (21 +/- 0.9% vs. 26 +/- 2.3%). In acute form fatty liver, electron microscopic examination revealed dramatic subcellular changes, such as vesicular transformation, a markedly increased amount of smooth endoplasmic reticulum (SER), and disruption of the crista. These changes were not found in the chronic form fatty liver. From this study, we concluded that the ultrastructural alteration in the subcellular organelles of hepatocyte might play a crucial role for the chameleonic presentation of MR tissue parameters in fatty liver.

Azepanone-based inhibitors of human and rat cathepsin K

The synthesis, in vitro activities, and pharmacokinetics of a series of azepanone-based inhibitors of the cysteine protease cathepsin K (EC 3.4.22.38) are described. These compounds show improved configurational stability of the C-4 diastereomeric center relative to the previously published five- and six-membered ring ketone-based inhibitor series. Studies in this series have led to the identification of 20, a potent, selective inhibitor of human cathepsin K (K(i) = 0.16 nM) as well as 24, a potent inhibitor of both human (K(i) = 0.0048 nM) and rat (K(i,app) = 4.8 nM) cathepsin K. Small-molecule X-ray crystallographic analysis of 20 established the C-4 S stereochemistry as being critical for potent inhibition and that unbound 20 adopted the expected equatorial conformation for the C-4 substituent. Molecular modeling studies predicted the higher energy axial orientation at C-4 of 20 when bound within the active site of cathepsin K, a feature subsequently confirmed by X-ray crystallography. Pharmacokinetic studies in the rat show 20 to be 42% orally bioavailable. Comparison of the transport of the cyclic and acyclic analogues through CaCo-2 cells suggests that oral bioavailability of the acyclic derivatives is limited by a P-glycoprotein-mediated efflux mechanism. It is concluded that the introduction of a conformational constraint has served the dual purpose of increasing inhibitor potency by locking in a bioactive conformation as well as locking out available conformations which may serve as substrates for enzyme systems that limit oral bioavailability.

Alterations in cerebral energy metabolism induced by traumatic brain injury

Energy metabolism of the brain is unique, possessing high aerobic metabolism with no significant capacity for anaerobic glycolysis and limited tissue stores of glucose. A steady supply of oxygen and glucose is essential in order to maintain cerebral function and integrity. Extensive research in experimental and human head injury has been conducted regarding the delivery of oxygen and outcome. This research has provided evidence which indicates that in addition to the availability of oxygen and glucose, other factors, such as perturbation of mitochondrial energy transducing processes which also follow head trauma, play significant roles. In this paper, the salient findings from biochemical studies of experimental and clinical brain injury are summarized and indicate that the mitochondrial respiratory chain-linked oxidative phosphorylation and calcium transport are compromised by trauma-induced brain injury and support the idea that oxidative stress and perturbation of cellular calcium homeostasis play significant roles in traumatic brain injury.

Synthesis of a fully functionalized protected C1-C11 fragment for the synthesis of the tedanolides

[figure: see text] The use of several non-aldol aldol processes allows one to prepare a fully functionalized and completely protected C1-C11 fragment that should be useful for the total synthesis of the tedanolides.