Birth-weight prediction by two- and three-dimensional ultrasound imaging

OBJECTIVES

To compare the accuracies of birth-weight predicting models derived from two-dimensional (2D) ultrasound parameters and from total fetal thigh volumes measured by three-dimensional (3D) ultrasound imaging; and to compare the performances of these formulae with those of previously published equations.

METHODS

A total of 210 patients were evaluated to create a formula-generating group (n = 150) and a prospective-validation group (n = 60). Polynomial regression analysis was performed on the first group to generate one equation based on 2D ultrasound measurements, one based on fetal thigh volume measured by the multiplanar technique (ThiM) and one based on fetal thigh volume obtained by the Virtual Organ Computer-aided AnaLysis (VOCAL()) method (ThiV). Paired-samples t-tests with Bonferroni adjustments were used to compare the performances of these equations in the formula-finding and the prospective-validation groups. The same approach was used to compare the accuracies of the new 2D and 3D formulae with those of both original and modified 2D equations from previous publications, as well as the 3D model reported by Chang et al.

RESULTS

The formulae with the best fit for the prediction of birth weight were: estimated fetal weight (EFW) = - 562.824 + 11.962x AC x FDL + 0.009 x BPD(2)x AC(2) (where AC is abdominal circumference, FDL is femur diaphysis length and BPD is biparietal diameter), EFW = 1033.286 + 12.733 x ThiM, and EFW = 1025.383 + 12.775 x ThiV. For both the formula-generating and the prospective-validation groups, there were no significant differences between the accuracies of the new 2D and 3D models in the prediction of birth weight. When applied to our population, the performances of the modified and original versions of the previously published 2D equations and the performance of the original 3D formula reported by Chang et al. were all significantly worse than our models.

CONCLUSIONS

We believe that the greatest sources of discrepancy in estimation of birth weight are the phenotypic differences among patients used to create each of the formulae mentioned in this study. Our data reinforce the need for customized birth-weight prediction formulae, regardless of whether 2D or 3D measurements are employed.

Fetal thigh volumetry by three-dimensional ultrasound: comparison between multiplanar and VOCAL techniques

OBJECTIVES

To evaluate the agreement between multiplanar and Virtual Organ Computer-aided AnaLysis (VOCAL()) techniques for the measurement of total fetal thigh volume and to assess the repeatability and reproducibility of measurements performed using these methods; to derive birth weight-predicting models for both methods and to compare their accuracies.

METHODS

This was a cross-sectional study of 150 singleton pregnancies at 30-42 weeks of gestation in which ultrasound volumes of the fetal thigh were obtained within 48 hours of delivery and measured using multiplanar and VOCAL techniques. Bland-Altman analyses were performed to determine the agreement between the two methods, and to evaluate intraobserver and interobserver variability in a subset of 40 patients. Birth weight-predicting models were derived using total fetal thigh volumes obtained using the VOCAL (ThiV) and multiplanar (ThiM) methods as independent variables. The accuracies of these formulas were compared.

RESULTS

The mean percentage difference between measurements performed using the VOCAL technique and the multiplanar technique was -0.04 and the 95% limits of agreement were -8.17 and 8.09. The mean percentage difference and 95% limits of agreement between paired measurements in the assessment of intraobserver and interobserver variability were -1.10 (-7.67 to 5.47) and 0.61 (-7.68 to 8.91) for the VOCAL technique and 1.03 (-6.35 to 8.41) and -0.68 (-11.42 to 10.06) for the multiplanar method, respectively. The best-fit formulas for predicting birth weight (BW) were: BW = 1025.383 + 12.775x ThiV; and BW = 1033.286 + 12.733x ThiM. There was no significant difference between the accuracies of these formulas.

CONCLUSIONS

There is good agreement between the VOCAL and multiplanar techniques for assessment of total fetal thigh volume. Measurements performed using both methods are repeatable and reproducible. For prediction of birth weight, the formulas generated in this study can be used interchangeably.

Heart stroke volume and cardiac output by four-dimensional ultrasound in normal fetuses

OBJECTIVE

To establish reference intervals for fetal heart stroke volume and cardiac output with gestation.

METHODS

Fetal heart ventricular volumes were measured using the four-dimensional (4D) spatiotemporal imaging correlation (STIC) ultrasound technique in 140 normal singleton pregnancies at 12-34 weeks' gestation. The Virtual Organ Computer-aided AnaLysis (VOCAL) technique was used to obtain a sequence of six sections of each ventricular volume in systole and diastole. Each volume was obtained after a 30 degrees rotation from the previous one around a fixed axis extending from the apex of the heart to the point that divides symmetrically each atrioventricular valve. The contour of each ventricle was drawn manually and the 4D volumes of the left and right ventricle in systole and diastole were estimated. The stroke volume for each ventricle was then calculated by subtracting the one in systole from the one in diastole and the cardiac output was calculated by multiplying the stroke volume by the fetal heart rate. In 50 cases the stroke volumes were measured by the same sonographer twice and the intraobserver agreement of measurements was calculated.

RESULTS

The left and right stroke volume and cardiac output increased exponentially with gestation, from respective mean values of 0.02 mL, 0.01 mL, 2.39 mL/min and 1.80 mL/min at 12 weeks to 0.30 mL, 0.32 mL, 43.46 mL/min and 46.72 mL/min at 20 weeks, and 2.07 mL, 2.67 mL, 284.71 mL/min and 365.99 mL/min at 34 weeks. The ratio of right to left stroke volume increased significantly with gestation from about 0.97 at 12 weeks to 1.13 at 34 weeks. In the Bland-Altman test, the mean percentage difference and 95% limits of intraobserver agreement for left stroke volume and right stroke volume were - 2.1 (-18.4, 14.2)% and - 0.8 (-16.4, 18.0)%, respectively.

CONCLUSIONS

In normal fetuses the stroke volume and cardiac output increase between 12 and 34 weeks' gestation. The extent to which, in pathological pregnancies, possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined.

Cardosins in postembryonic development of cardoon: towards an elucidation of the biological function of plant aspartic proteinases

Following on from previous work, the temporal and spatial accumulation of the aspartic proteinases (EC 3.4.23) cardosin A and cardosin B during postembryonic seed development of cardoon (Cynara cardunculus) was studied, mRNA and protein analyses of both cardosins suggested that the proteins accumulate during seed maturation, and that cardosin A is later synthesised de novo at the time of radicle emergence. Immunocytochemistry revealed that the precursor form of cardosin A accumulates in protein bodies and cell walls. This localisation in seeds is different from that previously described for cardoon flowers, suggesting a tissue-dependent targeting of the protein. It is known that procardosins are active and may have a role in proteolysis and processing of storage proteins. However, the presence of procardosin A in seeds could be related to the proposed role of the plant-specific insert in membrane lipid conversion during water uptake and solute leakage in actively growing tissues. This is in accordance with the recently proposed bifunctional role of aspartic proteinase precursor molecules that possess a membrane-destabilising domain in addition to a protease domain. Mature cardosin B, but not its mRNA, was detected in the first hours after seed imbibition and disappeared at the time of radicle emergence. This extracellular aspartic protease has already been implicated in cell wall loosening and remodelling, and its role in seed germination could be related to loosening tissue constraints for radicle protusion. The described pattern of cardosin A and B expression suggests a finely tuned developmental regulation and prompts an analysis of their possible roles in the physiology of postembryonic development.

Three-dimensional evaluation of mid-facial hypoplasia in fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks of gestation

OBJECTIVE

To investigate the mid-facial hypoplasia of fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks of gestation, by three-dimensional (3D) evaluation of the maxilla and the nasal bones.

METHODS

A 3D volume of the fetal head was obtained before fetal karyotyping at 11 + 0 to 13 + 6 (median 12) weeks of gestation in 80 fetuses that were subsequently found to have trisomy 21 and in 862 fetuses subsequently found to be chromosomally normal. The multiplanar mode was used to obtain a sequence of transverse views of the fetal face and to demonstrate the maxilla, the adjacent rami of the mandible and the nasal bones. The maxillary depth, defined as the distance between the alveolus of the maxilla in the midline anteriorly and the midpoint of the line joining the rami posteriorly, was measured. Ossification of the nasal bones was considered to be normal if both bones were more echogenic than the overlying skin.

RESULTS

In the chromosomally normal group the maxillary depth increased linearly with crown-rump length (CRL) from 3.1 mm at a CRL of 45 mm to 4.8 mm at a CRL of 84 mm, and in the trisomy 21 fetuses the depth was significantly smaller than normal (mean difference = - 0.3 mm, P < 0.001). There was no significant association between the delta maxillary depth and delta nuchal translucency thickness in either the trisomy 21 or the chromosomally normal fetuses. Impaired ossification of the nasal bones was observed in 3.1% of the chromosomally normal fetuses and in 60.0% of those with trisomy 21. The mean maxillary depth was significantly smaller in fetuses demonstrating impaired ossification than in those with normal ossification of the nasal bones (mean difference = -0.2 mm; 95% CI, -0.3 to -0.1, P = 0.001).

CONCLUSIONS

In a high proportion of fetuses with trisomy 21 there is sonographic evidence of mid-facial hypoplasia at 11 + 0 to 13 + 6 weeks of gestation.

Placental volume in twin and triplet pregnancies measured by three-dimensional ultrasound at 11 + 0 to 13 + 6 weeks of gestation

OBJECTIVE

To compare the placental volume at 11 + 0 to 13 + 6 weeks' gestation between singleton and multiple pregnancies and to examine the possible effect of chorionicity on placental volume.

METHODS

The placental volume was measured by three-dimensional (3D) ultrasound using the Virtual Organ Computer-aided AnaLysis (VOCAL) technique in 290 consecutive twin and 37 triplet pregnancies at 11 + 0 to 13 + 6 weeks of gestation. For the comparison of twin, triplet and singleton placental volumes each measurement was expressed as a multiple of the median (MoM) for singletons, previously established from the study of 417 normal fetuses at 11 + 0 to 13 + 6 weeks of gestation.

RESULTS

Median twin and triplet placental volumes were 1.66 and 2.28 MoM for singletons, respectively. In twins the placental volumes increased significantly with gestation from a median of 83.6 mL (5th and 95th centiles: 56.0 mL and 124.9 mL) at 11 + 0 weeks to 149.3 mL (5th and 95th centiles: 100.0 mL and 223.1 mL) at 13 + 6 weeks. The median MoM in monochorionic twins was not significantly different from that in dichorionic twins with fused placentas or dichorionic twins with separate placentas. In triplets the placental volumes increased significantly with gestation from a median of 114.9 mL (5th and 95th centiles: 77.6 mL and 170.1 mL) at 11 weeks to 217.9 mL (5th and 95th centiles: 147.2 mL and 322.5 mL) at 13 + 6 weeks. There were no significant differences in total placental volume between monochorionic and dichorionic triplets, monochorionic and trichorionic triplets, or dichorionic and trichorionic triplets.

CONCLUSIONS

Placental volume in multiple pregnancies does not depend on chorionicity, and the rate of placental growth between 11 and 13 + 6 weeks is not significantly different between singletons, twins and triplets. Moreover, for a given gestational age the placental volume corresponding to each fetus in twins and triplets is 83% and 76%, respectively, of the placental volume in singletons.

Metopic suture in fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks of gestation

OBJECTIVE

To investigate the development of the frontal bones and metopic suture in fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks of gestation.

METHODS

Three-dimensional (3D) ultrasound was used to measure the height of and gap between the frontal bones in 75 fetuses with trisomy 21 and these were compared to the measurements in 200 normal fetuses at 11 + 0 to 13 + 6 (median, 12 + 6) weeks of gestation.

RESULTS

In the fetuses with trisomy 21, compared to the normal fetuses, there was no significant difference in either the height of the frontal bones (mean difference 0.16 SD, range -1.78 to 2.17 SD; P = 0.369) or the gap between them (mean difference 0.012, 95% CI -0.073 to 0.097; P = 0.780). Additionally, within the group of trisomy 21 fetuses there were no significant differences in the development of the frontal bones and metopic suture between those with absent (n = 46) and those with present (n = 29) nasal bone.

CONCLUSIONS

In trisomy 21 the development of the frontal bones and metopic suture is as normal and is independent from the development of the nasal bones.

Metopic suture in fetuses with holoprosencephaly at 11 + 0 to 13 + 6 weeks of gestation

OBJECTIVE

To investigate the development of the metopic suture in fetuses with holoprosencephaly at 11 + 0 to 13 + 6 weeks of gestation.

METHODS

Three-dimensional (3D) ultrasound was used to measure the height and gap between the frontal bones in 200 normal fetuses and in nine fetuses with holoprosencephaly at 11 + 0 to 13 + 6 (median, 12) weeks of gestation.

RESULTS

In the 200 normal fetuses, the height of the frontal bones increased significantly with gestation from a mean of 2.5 mm (5(th) and 95(th) centiles: 1.9 mm and 3.3 mm) at 11 weeks to 6.1 mm (5(th) and 95(th) centiles: 4.6 mm and 8.1 mm) at 13 + 6 weeks. The gap between the two frontal bones did not change significantly with gestation (mean: 1.5 mm; 5(th) centile: 1.0 mm; 95(th) centile: 2.0 mm). In fetuses with holoprosencephaly, the height of the frontal bones was significantly larger (mean difference, 5.6 SDs; range, 3.9-7.7 SDs; P < 0.0001) and the gap was significantly smaller (mean 0.2 mm, range 0-0.8 mm; P < 0.0001) than those in normal fetuses.

CONCLUSIONS

Holoprosencephaly is associated with an accelerated development of the frontal bones and premature closure of the metopic suture.

Metopic suture in fetuses with Apert syndrome at 22-27 weeks of gestation

OBJECTIVES

To examine the possible association of skull deformity and the development of the cranial sutures in fetuses with Apert syndrome.

METHODS

Three-dimensional (3D) ultrasound was used to examine the metopic and coronal sutures in seven fetuses with Apert syndrome at 22-27 weeks of gestation. The gap between the frontal bones in the transverse plane of the head at the level of the cavum septi pellucidi was measured and compared to findings in 120 anatomically normal fetuses undergoing routine ultrasound examination at 16-32 weeks.

RESULTS

In the normal group, the gap between the frontal bones in the metopic suture at the level of the cavum septi pellucidi, decreased significantly with gestation from a mean of 2.2 mm (5th and 95th centiles: 1.5 mm and 2.9 mm) at 16 weeks to 0.9 mm (5th and 95th centiles: 0.3 mm and 1.6 mm) at 32 weeks. In the seven cases with Apert syndrome, two-dimensional ultrasound examination demonstrated the characteristic features of frontal bossing, depressed nasal bridge and bilateral syndactyly. On 3D examination there was complete closure of the coronal suture and a wide gap in the metopic suture (15-23 mm).

CONCLUSION

In normal fetuses, cranial bones are believed to grow in response to the centrifugal pressure from the expanding brain and proximity of the dura to the suture is critical in maintaining its patency. In Apert syndrome, the frontal bossing may be a mere consequence of a genetically predetermined premature closure of the coronal suture. Alternatively, there is a genetically predetermined deformation of the brain, which in turn, through differential stretch of the dura in the temporal and frontal regions, causes premature closure of the coronal suture and impaired closure of the metopic suture.

Three-dimensional sonographic description of abnormal metopic suture in second- and third-trimester fetuses

OBJECTIVE

To describe patterns of abnormal development of the metopic suture in association with fetal malformations during the second and third trimesters of pregnancy.

METHODS

This was a cross-sectional study of the frontal bones and metopic suture in 11 fetuses at 17-32 weeks of gestation. Cases were selected because there were obvious abnormalities in the metopic sutures. In each case, a malformation was detected by two-dimensional (2D) ultrasound and the abnormality of the metopic suture was detected and evaluated on three-dimensional (3D) ultrasound, using transparent maximum mode.

RESULTS

There were essentially four patterns of abnormality in the metopic suture: firstly, delayed development with a V- or Y-shaped open suture, which is found in normal fetuses at 12-16 weeks; secondly, a U-shaped open suture, presumably due to upward growth of the frontal bones with delayed closure; thirdly, premature closure of the suture, which is normally observed after 32 weeks; fourthly, the presence of additional bone between the frontal bones. Premature closure of the suture or additional bone between the frontal bones was observed in fetuses with holoprosencephaly and abnormalities of the corpus callosum, whereas the V-, Y- and U-shaped metopic sutures were observed in fetuses with facial defects involving the orbits, nasal bones, lip, palate and mandible, in the absence of holoprosencephaly and abnormal corpus callosum.

CONCLUSIONS

This preliminary study describes the pattern of possible abnormalities of the metopic suture and should stimulate further investigation to establish the prevalence and evolution of abnormal sutures as well as the incidence and pattern of other associated defects.

Three-dimensional sonographic description of the fetal frontal bones and metopic suture

OBJECTIVE

To describe the morphology of the frontal bones and metopic suture at 9-34 weeks of gestation using three-dimensional (3D) ultrasonography.

METHODS

This was a cross-sectional study of the frontal bones and metopic suture in 16 fetuses at 9-34 weeks of gestation. 3D ultrasonography was used to obtain volumes of the whole fetal skull in the mid-sagittal plane. The volumes were analyzed using the rendering mode and transparent maximum mode in order to achieve a clear view of the frontal bones and the metopic suture.

RESULTS

At 9 weeks, a small ossification center was visible in the middle of each supraorbital part of the frontal bones and by 11 weeks the frontal bones appeared as 'thick eyebrows'. In the second trimester there was progressive radial bone expansion and delineation of the metopic suture and in the third trimester there was closure of the metopic suture, starting from the glabella and moving upwards towards the anterior fontanelle.

CONCLUSIONS

This study provides 3D ultrasound images that illustrate the process of ossification of the frontal bones and the subsequent development of the metopic suture during prenatal life.

Placental volume measured by three-dimensional ultrasound at 11 to 13 + 6 weeks of gestation: relation to chromosomal defects

OBJECTIVE

To determine the potential value of measuring the placental volume at 11 to 13 + 6 weeks of gestation in screening for chromosomal defects.

METHODS

The placental volume was measured using three-dimensional ultrasound in 500 consecutive singleton pregnancies immediately before chorionic villus sampling for fetal karyotyping at 11 to 13 + 6 (median, 12) weeks of gestation.

RESULTS

The fetal karyotype was normal in 417 pregnancies and abnormal in 83. In the chromosomally normal group the mean placental volume increased significantly with gestation from a mean of 51 mL (5th and 95th centiles: 31.2 and 82.4 mL) at 11 weeks to 91 mL (5th and 95th centiles: 55.7 and 147.2 mL) at 13 + 6 weeks. In the chromosomally abnormal group the mean placental volume for gestational age was not significantly different from normal in trisomy 21 and Turner syndrome, but it was smaller in trisomies 13 and 18.

CONCLUSIONS

The measurement of the placental volume at 11 to 13 + 6 weeks of gestation is unlikely to be a useful predictor of the major chromosomal defects. In trisomies 13 and 18 the small placental volume may be due to early-onset fetal growth restriction, which could be the consequence of impaired placental function.

Gestational sac volume measured by three-dimensional ultrasound at 11 to 13 + 6 weeks of gestation: relation to chromosomal defects

OBJECTIVE

To determine the potential value of measuring the gestational sac volume (GSV) at 11 to 13 + 6 weeks of gestation in screening for chromosomal defects.

METHODS

The GSV was measured using three-dimensional (3D) ultrasound in 500 consecutive singleton pregnancies immediately before chorionic villus sampling (CVS) for fetal karyotyping at 11 to 13 + 6 (median 12) weeks of gestation.

RESULTS

The fetal karyotype was normal in 417 pregnancies and abnormal in 83. In the chromosomally normal group, the mean GSV increased significantly with gestational age from a mean of 69 mL at 11 weeks to 144 mL at 13 + 6 weeks (the standard deviation was 27 mL). In the chromosomally abnormal group, the mean GSV for gestational age was not significantly different from normal in fetuses with trisomy 21, trisomy 18 and Turner syndrome, but it was smaller in those with triploidy and trisomy 13. However, the mean GSV for crown-rump length (CRL) was significantly larger in trisomy 18, smaller in triploidy and trisomy 13, and not different from normal in trisomy 21 and Turner syndrome. The mean CRL for gestational age was significantly smaller than normal in trisomy 18, triploidy and trisomy 13.

CONCLUSIONS

The measurement of the GSV at 11 to 13 + 6 weeks of gestation is unlikely to provide useful prediction of the major chromosomal defects. In trisomy 13 and triploidy, the small GSV may be due to early onset fetal growth restriction and reduced amniotic fluid volume. In trisomy 18, the increase in GSV is probably due to the presence of associated fetal abnormalities that interfere with fetal swallowing.

Assessment of the gap between the fetal nasal bones at 11 to 13 + 6 weeks of gestation by three-dimensional ultrasound

OBJECTIVE

To detect the presence of a gap between the fetal nasal bones at 11 to 13 + 6 weeks of gestation and to verify if this gap could lead to the erroneous diagnosis of absent nasal bone.

METHODS

Three-dimensional (3D) ultrasound was used to assess the fetal nose in 450 singleton pregnancies, immediately after two-dimensional (2D) evaluation of the nasal bones and screening for chromosomal defects by a combination of maternal age and the measurement of fetal nuchal translucency at 11 to 13 + 6 (median, 12) weeks of gestation. A 3D volume of the fetal face was acquired and then analyzed using the multiplanar mode. A sequence of transverse views was used to confirm the presence or absence of the nasal bones and when they were present any visible gap between them was measured. A perfectly mid-sagittal plane was then examined to determine if the nasal bone was visible or not.

RESULTS

In 421/450 (93.6%) cases the nasal bone was present during 2D ultrasound. Using the multiplanar mode of 3D ultrasound, in 83/421 (19.7%) fetuses a gap between the nasal bones could be demonstrated and in 36/83 (43.4%) cases the nasal bone was found to be absent in the perfect mid-sagittal view. In 29/450 (6.4%) cases the nasal bones were absent during the 2D scan. In the 3D assessment there was absence of both bones in 25/29 (86.2%) cases and absence of one of the two bones in 4/29 (13.8%) cases. Chorionic villus sampling demonstrated that the fetal karyotype was normal in 404 and abnormal in 46 cases, including 31 cases of trisomy 21. There was absence of one or both nasal bones in three (0.7%) of the chromosomally normal fetuses, in 19 (61.3%) with trisomy 21 and in seven (46.7%) with other chromosomal defects.

CONCLUSIONS

At 11 to 13 + 6 weeks of gestation there is a gap between the nasal bones in about 20% of fetuses, and in about 40% of these cases in the perfect mid-sagittal plane the nasal bone may erroneously be considered to be absent.

Two African swine fever virus proteins derived from a common precursor exhibit different nucleocytoplasmic transport activities

African swine fever virus (ASFV), a large icosahedral deoxyvirus, is the causative agent of an economically relevant hemorrhagic disease that affects domestic pigs. The major purpose of the present study was to investigate the nuclear transport activities of the ASFV p37 and p14 proteins, which result from the proteolytic processing of a common precursor. Experiments were performed by using yeast-based nucleocytoplasmic transport assays and by analysis of the subcellular localization of different green fluorescent and Myc fusion proteins in mammalian cells. The results obtained both in yeast and mammalian cells clearly demonstrated that ASFV p14 protein is imported into the nucleus but not exported to the cytoplasm. The ability of p37 protein to be exported from the nucleus to the cytoplasm of both yeast and mammalian cells was also demonstrated, and the results clearly indicate that p37 nuclear export is dependent on the interaction of the protein with the CRM-1 receptor. In addition, p37 was shown to exhibit nuclear import activity in mammalian cells. The p37 protein nuclear import and export abilities described here constitute the first report of a nucleocytoplasmic shuttling protein encoded by the ASFV genome. Overall, the overlapping results obtained for green fluorescent protein fusions and Myc-tagged proteins undoubtedly demonstrate that ASFV p37 and p14 proteins exhibit nucleocytoplasmic transport activities. These findings are significant for understanding the role these proteins play in the replication cycle of ASFV.

Molecular cloning and characterization of cDNA encoding cardosin B, an aspartic proteinase accumulating extracellularly in the transmitting tissue of Cynara cardunculus L

Cardosins A and B are related aspartic proteinases from the pistils of Cynara cardunculus L., whose milk-clotting activity has been exploited for the manufacture of cheese. Here we report the cloning of cardosin B cDNA and its organ, tissue and cytological localization. The cDNA-derived amino acid sequence has 73% similarity with that of cardosin A and displays several distinguishing features. Cardosin B mRNA was detected in young inflorescences but not in pistils of fully opened inflorescences, indicating that its expression is developmentally regulated. The proteinase, however, accumulates in the pistil until the later stages of floral development. Immunocytochemistry with a monospecific antibody localized cardosin B to the cell wall and extracellular matrix of the floral transmitting tissue. The location of cardosin B in the pistil is therefore clearly different from that of cardosin A, which was found at protein storage vacuoles of the stigmatic papillae and has been suggested to be involved in RGD-mediated proteolytic mechanisms. In view of these results the possible functions of cardosin B in the transmitting tissue are discussed.

The saposin-like domain of the plant aspartic proteinase precursor is a potent inducer of vesicle leakage

A unique feature of plant aspartic proteinase precursors is the presence of an internal domain, known as plant-specific insert, whose function is not completely understood. The three-dimensional structure of the plant-specific insert resembles that of saposin-like proteins, a group of lipid-binding proteins involved in a variety of physiological processes. Here we show that recombinant plant-specific insert is able to interact with phospholipid vesicles and to induce leakage of their contents in a pH- and lipid-dependent manner. The leakage activity is higher at pH 4.5 and requires the presence of acidic phospholipids such as phosphatidylserine. To determine whether the same effect could be observed when the plant-specific insert is part of the precursor form, procardosin A and a mutant form lacking this specific domain were produced and characterized. Procardosin A displays a similar activity profile, whereas the mutant without the plant-specific insert shows only residual activity. These findings indicate that the plant-specific insert domain of plant aspartic proteinases mediates an interaction of their precursors with phospholipid membranes and induces membrane permeabilization. It is therefore possible that the plant-specific insert, alone or in conjunction with the proteolytic activity of plant aspartic proteinases, may function either as a defensive weapon against pathogens or in late autolysis of plant cells.

Identification of an Arg403Gln beta myosin heavy chain gene mutation in a Portuguese family with hypertrophic cardiomyopathy

INTRODUCTION

The etiology of Familial Hypertrophic Cardiomyopathy (HCM) is attributed to the mutation of genes that encode sarcomeric proteins in the heart. Until now no gene mutations had been identified in Portuguese families with HCM.

OBJECTIVE

The main objective of this study is to describe a Portuguese family with HCM carrying an Arg403Gln mutation in the beta myosin heavy chain gene.

METHODS

With the help of several Molecular Biology tools, 40 families with HCM were studied. In all these families, one member was identified as carrying an Arg403Gln mutation in the beta myosin heavy chain gene. All family members were submitted to a physical exam, EKG and echocardiography. Those carrying a gene mutation were also submitted to Holter monitoring and to magnetic ressonance imaging.

RESULTS

Molecular biology techniques are extremely important for the diagnosis of HCM, particularly in healthy carriers.

CONCLUSION

The use of molecular diagnostic tools in HCM is very useful because it allows us to identify the healthy carriers and establish earlier clinical and prevention programs for these individuals.

Cloning and characterization of cDNA encoding cardosin A, an RGD-containing plant aspartic proteinase

Cardosin A is an abundant aspartic proteinase from pistils of Cynara cardunculus L. whose milk-clotting activity has been exploited for the manufacture of cheese. Here we report the cloning and characterization of cardosin A cDNA. The deduced amino acid sequence contains the conserved features of plant aspartic proteinases, including the plant-specific insertion (PSI), and revealed the presence of an Arg-Gly-Asp (RGD) motif, which is known to function in cell surface receptor binding by extracellular proteins. Cardosin A mRNA was detected predominantly in young flower buds but not in mature or senescent pistils, suggesting that its expression is likely to be developmentally regulated. Procardosin A, the single chain precursor, was found associated with microsomal membranes of flower buds, whereas the active two-chain enzyme generated upon removal of PSI is soluble. This result implies a role for PSI in promoting the association of plant aspartic proteinase precursors to cell membranes. To get further insights about cardosin A, the functional relevance of the RGD motif was also investigated. A 100-kDa protein that interacts specifically with the RGD sequence was isolated from octyl glucoside pollen extracts by affinity chromatography on cardosin A-Sepharose. This result suggests that the 100-kDa protein is a cardosin A receptor and indicates that the interaction between these two proteins is apparently mediated through RGD recognition. It is possible therefore that cardosin A may have a role in adhesion-mediated proteolytic mechanisms involved in pollen recognition and growth.

Crystal structure of cardosin A, a glycosylated and Arg-Gly-Asp-containing aspartic proteinase from the flowers of Cynara cardunculus L

Aspartic proteinases (AP) have been widely studied within the living world, but so far no plant AP have been structurally characterized. The refined cardosin A crystallographic structure includes two molecules, built up by two glycosylated peptide chains (31 and 15 kDa each). The fold of cardosin A is typical within the AP family. The glycosyl content is described by 19 sugar rings attached to Asn-67 and Asn-257. They are localized on the molecular surface away from the conserved active site and show a new glycan of the plant complex type. A hydrogen bond between Gln-126 and Manbeta4 renders the monosaccharide oxygen O-2 sterically inaccessible to accept a xylosyl residue, therefore explaining the new type of the identified plant glycan. The Arg-Gly-Asp sequence, which has been shown to be involved in recognition of a putative cardosin A receptor, was found in a loop between two beta-strands on the molecular surface opposite the active site cleft. Based on the crystal structure, a possible mechanism whereby cardosin A might be orientated at the cell surface of the style to interact with its putative receptor from pollen is proposed. The biological implications of these findings are also discussed.

Partial purification of acetylcholine receptor binding components from the Duvernoy's secretions of blanding's tree snake (Boiga blandingi) and the mangrove snake (Boiga dendrophila)

Acetylcholine receptor (AChR) binding activity was detected in Duvernoy's secretions from B. blandingi and B. dendrophila as they competitively inhibited formation of 3[H]bungarotoxin-acetylcholine receptor complexes (3[H]Bgt-AChR) in a concentration-dependent manner. Secretions contained two types of toxin: low affinity and high affinity. Reversed-phase HPLC of B. blandingi and B. dendrophila secretions afforded 20 and 14 peaks, respectively. AChR binding components, as revealed by SDS-PAGE, had apparent molecular weights of 10 and 11 kDa (B. blandingi) or 11 and 12 kDa (B. dendrophila). Periodic acid-Schiff staining indicated these were not glycoproteins. Alkylation with 4-vinylpyridine significantly decreased their ability to inhibit 3[H]Bgt-AChR binding, indicating disulphide bridges were necessary for receptor-binding activity. Attempts to sequence the B. blandingi peptides were negative as these components seemed to be N-terminally blocked.

Identification and proteolytic processing of procardosin A

Plant aspartic proteinases contain a plant-specific insert (PSI) of about 100 amino acids of unknown function with no similarity with the other aspartic proteinases but with significant similarity with saposins, animal sphingolipid activator proteins. PSI has remained elusive at the protein level, suggesting that it may be removed during processing. To understand the molecular relevance of PSI, the proteolytic processing of cardosin A, the major aspartic proteinase from the flowers of cardoon (Cynara cardunculus L.) was studied. Procardosin A, a 64-kDa cardosin A precursor containing PSI and the prosegment was identified by immunoblotting using monospecific antibodies against PSI and the prosegment. Procardosin A undergoes proteolytic processing as the flower matures. PSI was found to be removed before the prosegment, indicating that during processing the enzyme acquires a structure typical of mammalian or microbial aspartic proteinase proforms. In vitro studies showed that processing of PSI occurs at pH 3.0 and is inhibited by pepstatin A and at pH 7.0. Sequence analysis allowed the identification of the cleavage sites, revealing that PSI is removed entirely, probably by an aspartic proteinase. Cleavage of the PSI scissile bonds requires, however, a conformation specific to the precursor since isolated cardosins and pistil extracts were unable to hydrolyse synthetic peptides corresponding to the cleavage sites. In view of these results, a model for the proteolytic processing of cardosin A is proposed and the molecular and physiological relevance of PSI in plant aspartic proteinase is discussed.

[Hypertrophic myocardiopathy: a sarcomere disease?]

The introduction of molecular biology in Cardiology opened a new era, in which the collaboration between geneticists, molecular biologists and cardiologists will allow the clinical application of Molecular Cardiology. In this review the new advances in the diagnosis and prognostic evaluation of patients with Hypertrophic Cardiomyopathy at the molecular level are discussed. We also present a summary of our current knowledge on the genetic bases and molecular mechanisms of this disease. Finally, some possibilities of the future clinical application of the data obtained by Genetic and Molecular Biology are shown. The Molecular Biology of Hypertrophic Cardiomyopathy expanded our horizons beyond the morphologic definitions, exposing the limitations of traditional concepts. However, we should not forget the potential drawbacks of these genetic tests, in order to anticipate and prevent the problems associated with their performance.

Action on bovine alpha s1-casein of cardosins A and B, aspartic proteinases from the flowers of the cardoon Cynara cardunculus L

The cleavage of purified bovine alpha s1-casein separately by cardosin A and cardosin B, two distinct milk-clotting aspartic proteinases (APs) present in the stigmas of the plant Cynara cardunculus L., was studied. Casein digestion peptides were separated either by SDS-PAGE or by reverse-phase HPLC, and their N-terminal amino acid sequences were subsequently determined by automated Edman degradation, thus identifying the cleavage sites. Results showed that both enzymes exert a similar but distinct action on bovine alpha s1-casein. In common they have the preference for the bond Phe23-Phe24, and the cleavage of Trp164-Tyr165 and Phe153-Tyr154. Cardosin A also cleaves the bond Tyr165-Tyr166, whereas Cardosin B cleaves an extra type of bond, Phe150-Arg151, revealing a slightly broader specificity. A model for the action of both enzymes on bovine alpha s1-casein is proposed and discussed. In comparison with the reported action of chymosin on bovine alpha s1-casein, both cardosins proved to have a broader specificity towards this particular substrate due to a higher ability to cleave bonds between residues with large hydrophobic side-chains.

Purification, characterization and partial amino acid sequencing of two new aspartic proteinases from fresh flowers of Cynara cardunculus L

Two new aspartic proteinases have been isolated from stigmas of the cardoon Cynara cardunculus L. by a two-step purification procedure including extraction at low pH, gel filtration on Superdex 200, and ion-exchange chromatography on Mono Q. To follow the conventional nomenclature for aspartic proteinases, we have named these proteinases cardosin A and cardosin B. On SDS/PAGE, cardosin A migrated as two bands with apparent molecular masses of 31 000 Da and 15 000 Da whereas the chains of cardosin B migrated as bands of 34 000 Da and 14 000 Da. The partial amino acid sequences of the two cardosin revealed that they are similar but not identical, and that they differ from the previously reported cardoon proteinases named cynarases, which were assumed to be derived from a common precursor. Although the cardosins show some degree of similarity to each other, we could detect no immunological crossreactivity between them. Both cardosins were active at low pH and were inhibited by pepstatin, with Ki values of 3 nM for cardosin A and 1 nM for cardosin B, indicating that they belong to the class of aspartic proteinases. Significant differences between the two enzymes were also found for the Kcat/km values for the hydrolysis of two chromophoric synthetic peptides. The active-site ionization constants, pKe1 and pKe2, for cardosin A are 2.5 +/- 0.2 and 5.3+/- 0.2, whereas for cardosin B they are 3.73 +/- 0.09 and 6.7 +/- 0.1. The results herein described on the structural and kinetic properties of the cardosins indicate that they are the products of distinct genes which have probably arisen by gene duplication. A scheme for the proteolytic processing of the two enzymes is also proposed.