Genomic affinities between maize and Zea perennis using classical and molecular cytogenetic methods (GISH-FISH)

In this study we have analysed and compared the genomic composition, meiotic behaviour, and meiotic affinities of Zea perennis and Zea mays ssp. mays. To do so we studied the parental taxa and the interspecific hybrid Zea perennis x Zea mays ssp. mays, using classical cytogenetic methods, as well as GISH and FISH. GISH enabled us to recognize the genomic source of each chromosome involved in the meiotic configurations of this hybrid, and established the genomic affinities between their parental species. The results obtained here reinforce the hypothesis of the amphiploid origin of Zea perennis and, together with previous research, indicate that the chromosomes with divergent repetitive sequences in maize and Zea luxurians could be the remnants of a relict parental genome not shared with Zea perennis.

Simple approach to prenatal diagnosis of transposition of the great arteries

OBJECTIVE

To analyze the most relevant anomalies, seen in a sequential segmental transverse views approach to imaging the fetal heart, that provide clues to the diagnosis of complete transposition of the great arteries (TGA).

METHODS

We reviewed retrospectively all the cases of isolated TGA diagnosed in our center or submitted for a second opinion through the spatio-temporal image correlation (STIC) telemedicine (TELE-STIC) program. Only transverse cardiac sweeps were obtained. Digital video clips and STIC volumes were reviewed. The abnormal features on four-chamber, five-chamber, three-vessel (3V) and three vessels and trachea (3VT) views were analyzed.

RESULTS

The study population consisted of eight fetuses with TGA with normal extracardiac anatomy. The gestational age ranged from 13 to 32 (mean, 23) weeks. The maternal age ranged from 25 to 42 (mean, 32) years. A normal four-chamber view was seen in seven cases. Only one case demonstrated a significant ventricular septal defect. At the level of the five-chamber view a straight course arterial vessel arose from the left ventricle with lateral branches in all fetuses. In the 3V view, the ascending aorta was seen reaching more anteriorly than was the pulmonary artery in six cases. At the level of the 3VT view, two vessels (transverse aortic arch and superior vena cava) rather than three were seen in all cases.

CONCLUSION

Our proposed sequential segmental approach to imaging the fetal heart apparently allows, in five-chamber and 3VT views, clear and confident signs to be detected that aid diagnosis of TGA.

The genome organization and diversification of maize and its allied species revisited: evidences from classical and FISH-GISH cytogenetic analysis

The present review summarizes our classical and molecular cytogenetic investigations in the genus Zea. The results obtained from the meiotic behavior analysis of Zea species and hybrids, confirm the amphiploid nature of all species in the genus, with a basic number of x = 5 chromosomes. All species with 2n = 20 are diploidized allotetraploids, whereas Z. perennis (2n = 40) is an allooctoploid with four genomes somewhat divergent from one another. These analyses also revealed the existence of postzygotic reproductive isolation among Zea species. Our studies using genomic in situ hybridization (GISH) provide evidence about the evolutionary relationships among maize and its allied species, and reveal remarkable genomic divergences. Particularly, knob sequences were not completely shared between taxa previously considered to be closely related. Our data strongly suggest that the teosinte Z. mays parviglumis is not the only progenitor of cultivated maize. Introgression of Tripsacum into cultivated maize cannot be discarded.

GISHGenomic in situ hybridization reveals cryptic genetic differences between maize and its putative wild progenitor Zea mays subsp. parviglumis

The aim of this paper is to test with genomic in situ hybridization the genomic affinities between maize and its putative progenitor Zea mays subsp. parviglumis. Blocking procedures were applied for the purpose of improving discrimination among chromosome regions. Unlabeled genomic DNA from Z. mays subsp. parviglumis as a blocking agent and labeled genomic DNA from maize were hybridized on maize chromosomes. On the other hand, mitotic metaphases from Z. mays subsp. parviglumis were blocked with unlabeled genomic DNA of maize and hybridized with labeled genomic DNA from Z. mays subsp. parviglumis. Both experiments showed that either maize or Z. mays subsp. parviglumis chromosomes have their own unique sequences. This means an unexpected degree of divergence if Z. mays subsp. parviglumis is the only progenitor of maize, a result that is discussed in relation to our previous genomic in situ hybridization observations and to the different scenarios proposed about the origin of maize.

Three-dimensional yolk and gestational sac volume. A prospective study of prognostic value

OBJECTIVE

To evaluate the relative prognostic value of ultrasound findings during the first-trimester scan by univariate and logistic regression analysis in a group of asymptomatic women.

STUDY DESIGN

A total of 125 asymptomatic pregnant women with a singleton conceptus, concordance between menstrual age and crown-rump length, and documented fetal activity, 25 for each gestational age between 6 and 10 weeks, were enrolled in the study and underwent a transvaginal sonographic examination. The following data were collected: yolk sac mean diameter and volume, gestational sac mean diameter and volume, fetal heart rate, maternal age, gestational age and presence of a retrochorial hematoma. The outcome variable was abortion, defined as pregnancy loss at any time up to 20 weeks' gestation. Normograms were constructed for volumes, mean diameters and fetal heart rate. Receiver-operator characteristic curves were performed in order to dichotomize maternal and gestational age. Univeriate analysis was performed by Fisher's exact test. Logistic regression was performed to test the relationship between independent variables and pregnancy outcome.

RESULTS

In univariate analysis, the variables significantly associated with spontaneous abortion were maternal age > 34 years, yolk sac volume outside the 5th to 95th percentile, gestational sac volume < the 5th percentile and fetal heart rate outside the 5th to 95th percentile. In regression analysis only maternal age > 34 years, gestational sac mean diameter < 5th percentile and fetal heart rate outside the 5th to 95th percentile were significant in predicting abortion.

CONCLUSION

Our data suggest that new three-dimensional parameters are of no clinical benefit in the prediction of abortion in nonbleeding, first-trimester pregnancy, when conventional sonographic parameters are used.

Cardiac defects in chromosomally normal fetuses with increased nuchal translucency at 10-14 weeks of gestation

OBJECTIVE

To examine the prevalence, distribution and spectrum of cardiac defects in chromosomally normal fetuses with increased nuchal translucency thickness.

PATIENTS AND METHODS

During a 4-year period, targeted fetal echocardiography was used in 353 chromosomally normal fetuses with increased nuchal translucency thickness at 10-14 weeks' gestation. The cardiac scan was performed at 18-22 weeks. In the last 138 cases enrolled, an additional scan at 12-16 weeks was carried out. The follow-up included the findings at necropsy or in the pediatric examination. A complete follow-up was achieved in 97%.

RESULTS

Cardiac defects were present in 32 (9.1%) cases, increasing from 5.3% in those with a nuchal translucency thickness of > or = 95th centile (3.9 mm) to 24% when thickness > or = 6 mm (p < 0.001). In 31 cases (97%), the cardiac defect was diagnosed antenatally; in 24 cases (77%) this diagnosis was confirmed later. In the remaining seven cases, the autopsy examination was not available. A wide range of cardiac defects was observed, with the most common being atrioventricular septal defect and tricuspid atresia.

CONCLUSIONS

Euploid fetuses with increased nuchal translucency thickness have a significantly increased risk of cardiac defects. This is a marker of different types of heart anomalies and constitutes an additional indication for targeted fetal echocardiography. Most of the cardiac defects can be detected by fetal echocardiography.

References intervals for fetal biometrical parameters

OBJECTIVE

To establish normal reference intervals for biparietal diameter, head circumference, abdominal circumference, and length of femur, a cross-sectional study.

STUDY DESIGN

Five hundred singleton fetuses for each week at gestations between 23 and 41 weeks with a total of 9500 fetuses. Antenatal ultrasound measurements from all consecutive pregnant women referred to the ultrasound unit for scanning of fetal condition are prospectively entered in a data bank. For the purpose of this study, sonographic measurements were collected retrospectively and each fetus contributed just one value to the reference sample.

RESULTS

The mean curve of the four biometrical parameters varied with gestational age, with flattening of the curves at the end of gestation and increased width of normal ranges with increasing gestational age. Maximal weekly increases occurred at 24 weeks' gestation for head circumference, abdominal circumference, and length of femur and at 26 weeks' gestation for biparietal diameter. The four biometrical parameters, however, showed 50% increases in size at 33 weeks' gestation.

CONCLUSIONS

These fetal size reference intervals are clinically relevant and can be used for populations with epidemiological features and distribution of neonatal birth weights similar to our data.

Measurement of nuchal translucency as a single strategy in trisomy 21 screening: should we use any other marker?

OBJECTIVE

To evaluate the role of nuchal translucency thickness as a single marker in screening for trisomy 21 at 10-16 weeks' gestation.

METHODS

From December 1996 to October 2001, nuchal translucency was measured in 11,281 consecutive early second trimester fetuses referred to our unit for prenatal care and delivery. Scans were performed by eight experienced ultrasonographers, under strict methodological criteria.

RESULTS

Chromosomal abnormalities were found in 118 cases (52 trisomy 21). Using nuchal translucency greater than the 95th centile as a cut-off, the overall detection rate was 71.2% with a specificity of 95.4%, and a positive predictive value of 14%. In the trisomy 21 selected group, detection rate, specificity, and positive predictive value for nuchal translucency were 92.3%, 95.4%, and 8.5%, respectively. The detection rate of trisomy 21 reached 100% when nuchal translucency was measured between 10 and 14 weeks' gestation, maintaining the same specificity.

CONCLUSION

Early second trimester nuchal translucency measurement can achieve prenatal detection rates of trisomy 21 greater than 95% with a 5% false-positive rate. With a detection rate so high, the benefits of using additional markers may be less than previously considered. Although maternal age, other sonographic or Doppler markers, and maternal serum biochemistry might play a role in prenatal strategies to detect fetal chromosomal abnormalities, the high detection rate of trisomy 21 fetuses using nuchal translucency as a single parameter suggests that early nuchal translucency measurement between 10 and 14 weeks' gestation can be a simple screening strategy for this condition.

The role of ductus venosus blood flow assessment in screening for chromosomal abnormalities at 10-16 weeks of gestation

OBJECTIVE

To evaluate the role of ductus venosus blood flow assessment at 10-16 weeks' gestation in screening for chromosomal abnormalities.

METHODS

Ductus venosus blood flow was prospectively evaluated in 1371 consecutive pregnancies between 10 and 16 weeks of gestation. The pulsatility index for veins was calculated. All cases were screened for chromosomal defects combining maternal age and fetal nuchal translucency thickness.

RESULTS

A chromosomal abnormality was found in 20 cases. The overall detection rate, specificity, positive predictive value, negative predictive value and odds ratio for chromosomal abnormalities were 65%, 95.7%, 18.3%, 99.5% and 41 (95% CI 16-108), respectively, when using the 95th centile pulsatility index as a cut-off.

CONCLUSIONS

These preliminary results suggest that evaluation of the ductus venosus pulsatility index at 10-16 weeks' gestation is a useful second-line screening test for chromosomal defects. A combination of nuchal translucency measurement and ductus venosus assessment might increase specificity while maintaining an optimal detection rate for chromosomal abnormalities. Such a policy could identify 55% of all chromosomal abnormalities and about 69% of autosomal trisomies, reducing the need for invasive testing to less than 1%.

Selective versus non-selective laser photocoagulation of placental vessels in twin-to-twin transfusion syndrome

OBJECTIVE

We have recently described a surgical technique for the treatment of twin-to-twin transfusion syndrome (TTTS) that allows precise identification of vascular anastomoses (selective laser photocoagulation of communicating vessels, or S-LPCV). The purpose of this study was to compare S-LPCV with the previous non-selective technique (NS-LPCV) that targeted all vessels crossing the dividing membrane.

MATERIALS AND METHODS

Patients with TTTS were treated with NS-LPCV from May 1994 to June 1997 and with S-LPCV from July 1997 to December 1999. TTTS was defined as polyhydramnios of > or = 8 cm maximum vertical pocket (MVP) in the recipient twin and oligohydramnios of < or = 2 cm MVP in the donor twin. Outcome was measured as survival per number of pregnancies and per number of fetuses together with limited morbidity data.

RESULTS

NS-LPCV was used in 18 patients and 74 were treated with S-LPCV. Three patients interrupted their pregnancies electively after surgery (S-LPCV) and were removed from further analysis. Survival of at least one fetus was higher in S-LPCV (83.1%) than in NS-LPCV (61.1%) (P = 0.04), mostly due to a lower rate of dual intra-uterine fetal demise in S-LPCV (5.6%) than in NS-LPCV (22%) (P = 0.05). There were more hydropic fetuses in the NS-LPCV group (27%) than in the S-LPCV group (5.4%), but this difference did not account for the results. There was no difference in the survival per number of fetuses between the two groups.

CONCLUSIONS

S-LPCV represents an important evolution in the surgical treatment of TTTS. The use of this technique by all centers should allow better comparison of fetal survival and morbidity rates. S-LPCV should be the standard technique in trials comparing amniocentesis versus laser for the treatment of severe TTTS.

Genomic affinities of Zea luxurians, Z. diploperennis, and Z. perennis: Meiotic behavior of their F1 hybrids and genomic in situ hybridization (GISH)

Since 1987 cytological evidence has arisen in our laboratory, pointing to x = 5 as the original basic chromosome number of maize and its related wild species. This paper deals with the analysis of the meiotic behavior of F1 hybrids Zea luxurians × Z. diploperennis (2n = 20) and Z. luxurians × Z. perennis (2n = 30). In the first hybrid the most frequent configuration was 8ll + 4l and in the latter was 5lll + 5ll + 5l. Applying GISH (genomic in situ hybridization) to mitotic chromosomes of Z. luxurians we found that DAPI (4', 6-diamidino-2-phenylindole) positive bands located in all telomeric regions of this species did not hybridize with either Z. perennis or Z. diploperennis genomic probe. Therefore, Z. luxurians has a repetitive sequence that can be used in fluorescent staining to identify its chromosomes. When GISH was employed on metaphase I of the 2n = 30 hybrid, all the univalents showed distinctive telomeres of Z. luxurians, while the bivalents did not present any signal. These findings show that the formation of bivalent-univalent configurations is not a random event. The bivalents tend to be spatially separated and are very often observed forming an independent group of 5II. Finally, trivalents were composed by one chromosome labeled in its telomeric regions, and two smaller and unlabeled ones. The use of chromosome markers of Z. luxurians demonstrated to be a good step forward in interpreting the nature of meiotic configurations in 2n = 30 Zea spp. hybrids. They can help to clarify the relationship between genomes and provide a useful addition to the taxonomic classification in the genus Zea.Key Words: Zea hybrids, evolution, cytogenetics, repetitive sequences, heterochromatic knobs.

Genomic in situ hybridization (GISH) of Tripsacum dactyloides and Zea mays ssp. mays with B chromosomes

Genomic affinities between Tripsacum dactyloides (2n = 72) and Zea mays ssp. mays (2n = 20 + 5 B) were analyzed through GISH (genomic in situ hybridization) to ascertain the degree of chromosome homology between the two genera. Mitotic cells of T. dactyloides were simultaneously probed with total genomic DNA from Z. mays ssp .mays (2n = 20) and with rDNA (pTA71). A disperse pattern of hybridization signal among all 72 chromosomes, corresponding to maize total DNA, and six strong fluorescent signals due to the rDNA probe hybridizing on 3 chromosome pairs of T. dactyloides were observed. Mitotic chromosomes from Z. mays ssp. mays (2n = 20 + 5 B) were hybridized with a maize line that lacked B chromosomes and knobs and with total DNA from T. dactyloides. The knobless line of maize hybridized intensely on all chromosomes except for some regions where the probe bound less. Tripsacum dactyloides bound intensely on one terminal region of each B chromosome and to some regions of chromosome pairs 2, 6, and 8. These regions are DAPI positive and coincide with regions that displayed lower affinity with the probe from the knobless maize line. The possible significance of these results is discussed briefly.Key words: Tripsacum dactyloides, Zea mays ssp. mays, maize B chromosomes, genomic in situ hybridization, GISH.

[Gastrointestinal anisakiasis. Seven cases in three months]

Human anisakiasis or anisakidosis is an unusual parasitation. During the autumn of 1996 seven patients came to our Hospital for such a condition. Five of these patients had the parasites in the gastroduodenal area (1 in the gastric body, 3 in the antrum and 1 in the duodenal bulb, this one with two parasites). Four out of the five patients consulted us for intense epigastric pain; only one developed a cutaneous rash. The fifth patient was diagnosed unexpectedly during an endoscopy appointment. Eosinophilia was detected in none. All the parasites were extracted endoscopically and identified as belonging to the Anisakis genera. Excepting for the patient with no complaint, the other four showed adhered larvas to mucosa. The two other patients were operated because of acute abdominal pain. At laparotomy an ileitis was seen and then resected. Under microscopic examination both ileon were found to be edematous and infiltrated by eosinophils. Anisakis larvae were observed in the submucosa of one of the removed intestines. The other patient was diagnosed after an immunologic study consisting of radioimmunoassay and Western Blot. Five of the seven patients (71%) acquired the parasites after consumption of anchovies with vinegar.

Prenatal diagnosis of isolated hypospadias

Ten cases of prenatal diagnosis of isolated hypospadias are presented, six of them in the second trimester. The echographical basis for the suspected diagnosis of hypospadias are: anomalous distal morphology of the penis, small lateral folds (dermal remains of the prepuce), small penis with ventral incurving and anomalous urinary stream. The embryogenesis and the clinical utility of prenatal study of the genitals of the fetus, not only to determine the sex, but also to detect anomalies, are discussed.

Prenatal diagnosis of testicular torsion

A case of the prenatal diagnosis of testicular torsion at 39 weeks' gestation is presented. The affected testicle was observed as a small rounded area of hypoechogenicity with a peripheral echogenic ring without hydrocele. The appearance was suggestive of the chronic phase of testicular torsion. The neonatal genital exploration confirmed the diagnosis.

Early detection of reversed diastolic umbilical flow: should we offer karyotyping?

In normal pregnancy, end-diastolic flow appears in the umbilical artery around the 13th week of gestation, with a velocity which increases progressively with advancing gestation. The detection of reversed flow in the umbilical artery, the highest expression of an increase in placental vascular resistance, is extremely uncommon in the first half of gestation and, in three of the four cases reported in the literature, there were chromosomal abnormalities. We report a new case of reversed end-diastolic flow in the umbilical artery in a 13-week fetus with increased nuchal translucency thickness, megacystis and tachycardia. Cytogenetic analysis of chorionic villi and amniocytes revealed trisomy 13. The findings provide further evidence for a possible association between reversed end-diastolic flow in the umbilical artery and chromosomal abnormalities. However, the effectiveness of this potential marker in an unselected population requires further evaluation.

[Complete congenital atrioventricular block. Prenatal diagnosis and perinatal management]

OBJECTIVE

To describe our experience in prenatal diagnosis and perinatal management of congenital atrioventricular heart block, as well as pacemaker treatment in the neonate.

MATERIAL AND METHODS

A total of 13 fetuses are included. The diagnosis of atrioventricular dissociation was established by Doppler heart rate sample in the right atrium to show the atrial activity while the sample in the Aorta reflected the ventricular heart rate. Gestational age at diagnosis, ventricular heart rates, autoimmune maternal pathology, maternal blood tests for autoantibodies antiRo+, congenital structural heart disease, fetal hydrops, maternal medical treatment, perinatal results and pacemaker neonatal implantation are described.

RESULTS

Gestational age at diagnosis ranged between 22 and 32 (mean 27.6) weeks. Ventricular heart rates ranged between 32 to 80 (mean 54) beats/min. AntiRo+ antibodies were detected in 5 mothers, and clinical systemic lupus erythematosus was found in only one. Four had congenital heart disease (2 ventricular inversion and corrected TGA, 1 complete atrio-ventricular canal and 1 tricuspid atresia). Signs of heart failure and hydrops were detected in 9 fetuses. Treatment with beta-metasona and ritodrine was administered to 7 mothers when the ventricular heart rate dropped below 60 beats/min. Intrauterine fetal death occurred in 3 fetuses with structural congenital heart disease and hydrops. Delivery was performed by cesarean section in 8 preterm fetuses (one them a twins), 3 spontaneous deliveries at term and 3 stillbirth. Postnatal pacemaker implantation was carried out in 9 newborns (3 cases with unicameral temporal right ventricle electrode and 6 cases with permanent bicameral electrodes implanted through the subclavian vein and DDD pacemaker). Follow-up of the bicameral pacemaker group was satisfactory.

CONCLUSION

Persistent fetal bradycardia is the first sign to diagnose prenatal complete atrioventricular heart block. Echocardiography asses fetal haemodynamic status and may detect signs of fetal deterioration. Hydrops and further drop in the ventricular heart rate warrant urgent cesarean section and pacemaker management of the newborn.

Use of interferon-alpha in laryngeal papillomatosis: eight years of the Cuban national programme

Laryngeal papillomatosis is one of the first diseases where interferon (IFN) was found to be effective. In 1983, a programme for the treatment of all such cases started in Cuba. Up to December 1991, 125 patients (92 children, 33 adults) have been treated: 102 with leucocyte IFN-alpha, 12 with recombinant IFN-alpha-2b, and 11 have received both preparations. Case management consisted of surgical removal of the lesions followed by an IFN schedule starting with 10(5) IU/kg of weight in children or 6 x 10(6) IU in adults, i.m. daily. The dose was progressively reduced, as long as no relapses occurred. At the end of the one-year schedule the doses were reduced to 5 x 10(4) IU/kg in children or 3 x 10(6) IU in adults, weekly. If there was a relapse, it was removed surgically and the patient returned to a higher dose level. Most cases (89; 71 per cent) have not relapsed after the treatment; 60 of them have been followed for more than three years. In those with relapses, the frequency of recurrence decreased in all but four patients. The treatment seemed to be more effective if initiated less than three months after the disease onset. The tracheostomy could be removed in five out of seven patients who needed it before the IFN treatment and was necessary in only three new cases during IFN treatment. In two of these, decannulation was possible later on. In a total of 14 patients relapses persisted after several cycles of IFN treatment. They were considered resistant to such treatment. No severe side effects were reported. The most frequent ones were fever, drowsiness, increased bronchial secretion, chills and headache. The establishment of this programme has maintained the disease under control in Cuba.

Reversed end-diastolic umbilical artery velocity in two cases of trisomy 18 at 10 weeks' gestation

Doppler velocimetry of the umbilical artery was carried out during routine ultrasound examinations performed immediately before either chorionic villus sampling (n = 383) or genetic amniocentesis (n = 649) in 1032 women referred for prenatal diagnosis at our institution, between 10 and 18 weeks of gestation. Reversed end-diastolic flow was detected in only two cases (0.19%), both of which were affected by trisomy 18. The diagnosis was made at 10 weeks' gestation and, to our knowledge, these are the earliest records of this pathological Doppler pattern. Although a possible relationship with early abnormal placentation remains to be established, the finding of reversed end-diastolic velocities in the umbilical artery in the first trimester of pregnancy may be an early sign of karyotype abnormality.

First-trimester biochemical screening for Down syndrome with the use of PAPP-A, AFP, and beta-hCG

Biochemical screening for Down syndrome (DS) is well established in the second trimester of pregnancy, but there is little information available on its value in the first trimester. This study describes our preliminary results with biochemical screening for DS in the first trimester of pregnancy in order to evaluate its efficacy at this time. Our study population, including 19 DS pregnancies, was evaluated using maternal serum levels of alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (beta-hCG), and pregnancy-associated plasma protein A (PAPP-A). At a false positive rate (FPR) of 5 per cent, the detection rate (DR) for DS is 9 per cent for beta-hCG, 18 per cent for AFP, and 66 per cent for PAPP-A when considering these parameters individually. With different combinations of the analytes, the best detection rates are obtained with the association of PAPP-A and AFP (85 and 82 per cent DR for a 10 and 5 per cent FPR, respectively). Our data support the value of first-trimester biochemical screening for DS and that of PAPP-A as a single marker.