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Does fetal heart rate count in sex prediction? HCG from maternal blood and serum- explain. What is nested PCR? DNA analysis in relation to nested PCR. Ultra sound procedure- explain. What is Q-banding? Amniocentisis with full explaination of electrophoresis and fluorocence microscopy.

Answer 1

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1. Does fetal heart rate count in sex prediction?
ans. Heartrate "A heartrate of less than 140 beats per minute means that you're having a boy while a heartrate of over 140 beats per minute means that you're having a girl." Although this particular myth has been kicking around for decades, there's only one study on the books that supports it: a 1993 study at the University of Kentucky that concluded that the fetal heartbeat could be used to correctly predict the gender of 91% of male fetuses and 74% of female fetuses. Every other study conducted before or since has reached the exact opposite conclusion -- that the fetal heart-rate can't be used to predict the gender of your baby.

2. HCG from maternal blood and serum- explain.
ans. In preeclamptic pregnancies with male fetuses, the maternal serum hCG levels were significantly higher than in uncomplicated pregnancies. Total testosterone levels were significantly higher in pregnancies with either gender and significantly higher in male-bearing than in female-bearing pregnancies. This may indicate an androgen influence on the pathophysiologic mechanism of preeclampsia.

Human chorionic gonadotropin (hCG) is produced in the placental syncytiotrophoblast. The bulk of the hormone is secreted into the maternal circulation. During normal pregnancy the hCG levels increase rapidly until a peak is reached at 60–80 days’ gestation. Thereafter, the levels decrease, reaching a nadir at 16–18 weeks’ gestation.

3. What is nested PCR? DNA analysis in relation to nested PCR.
ans. Nested PCR means that two pairs of PCR primers were used for a single locus (figure 1). The first pair amplified the locus as seen in any PCR experiment. The second pair of primers (nested primers) bind within the first PCR product (figure 4) and produce a second PCR product that will be shorter than the first one (figure 5). The logic behind this strategy is that if the wrong locus were amplified by mistake, the probability is very low that it would also be amplified a second time by a second pair of primers.

Figure 1. Nested PCR strategy. Segment of DNA with dots representing nondiscript DNA sequence of unspecified length. The double lines represent a large distance between the portion of DNA illustrated in this figure. The portions of DNA shown with four bases in a row represent PCR primer binding sites, though real primers would be longer.
Figure 2. The first pair of PCR primers (blue with arrows) bind to the outer pair of primer binding sites and amplify all the DNA in between these two sites.
Figure 3. PCR product after the first round of amiplificaiton. Notice that the bases outside the PCR primer pair are not present in the product.
Figure 4. Second pair of nested primers (red with arrows) bind to the first PCR product. The binding sites for the second pair of primers are a few bases "internal" to the first primer binding sites.
Figure 5. Final PCR product after second round of PCR. The length of the product is defined by the location of the internal primer binding sites.
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4. What is Q-banding?
ans. A fluorescent stain for chromosomes, useful in identifying the Y-chromosome and certain DNA polymorphisms.

5. Amniocentisis with full explaination of electrophoresis and fluorocence microscopy.
ans. Amnio-PCR can be an alternative to conventional cytogenetic study for women with positive biochemical screening for fetal Down syndrome and no demonstrable fetal structural abnormality.

Second-trimester maternal serum screening for fetal Down syndrome has become an established practice in many countries.1 The use and acceptability of screening with human chorionic gonadotrophin, alpha-fetoprotein, and/or unconjugated estriol has been demonstrated by numerous large prospective intervention studies.1 Serum screening generates a ratio that characterizes the risk of Down syndrome in the fetus. Women being assigned a risk above an arbitrary cutoff are designated screen positive and offered amniocentesis for a karyotype. Conventional cytogenetic study of the cultured amniocytes is performed, and a full karyotype report is available within 2 to 3 weeks. In addition to chromosome 21, all the other chromosomes are also assessed.

Von Eggeling et al2 devised a polymerase chain reaction (PCR)–based test that allowed rapid detection of trisomy 21 in less than 24 hours. This technique can be applied to deoxyribonucleic acid (DNA) from uncultured amniotic fluid cells that have been amplified with small tandem repeat markers using the PCR technique and fluorescence-labeled primers (amnio-PCR).3 The small tandem repeat markers specific for chromosome 21 will only be able to detect aneuploidy of chromosome 21. In a masked prospective study where 2167 pregnant women were offered amniocentesis, Verma et al4 showed that the rapid test was informative in 99.6% of cases and there were no false-positive or false-negative diagnoses of Down syndrome.

We have performed amnio-PCR for various indications since 1999 in our Prenatal Diagnostic and Counselling Department. In all cases, the diagnosis was confirmed by conventional cytogenetic study. Positive Down syndrome screening is the second most common indication for amnio-PCR, the first being ultrasound abnormalities.

Our research question is whether amnio-PCR can replace conventional cytogenetic study for women with only positive biochemical screening for fetal Down syndrome. In other words, we want to assess the likely outcome if we were to change to a policy of PCR analysis without conventional cytogenetic study for all of the amniocentesis samples from women with positive biochemical screening for fetal Down syndrome and no fetal abnormality detected on ultrasound examination. The potential advantage of this approach is the relief of women’s anxiety during the 2- to 3-week waiting time for the conventional cytogenetic study report.5 The potential disadvantage of this approach is that other chromosomal abnormalities apart from aneuploidy in chromosome 21 would not be detected. It would be important to know how many of these undetectable chromosomal abnormalities are clinically significant if the corresponding ultrasound examination does not show any fetal abnormality.
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Answer 2

There is no distinct association with the fetal heart rate of your unborn baby and the determination of its sex.

As for your HCG from maternal blood and serum question, the best resource would be on this site. You may need to be more specific on your question though.

http://humrep.oxfordjournals.org/cgi/content/full/18/3/572

A nested PCR is a second round of PCR amplification that utilizes primers located internally to those used in the first round of amplification.
Also try websterdictionary.com

An Ultrasound procedure is the traditional ultrasound procedure involves placing gel on your abdomen to work as a conductor for the sound waves.

Q-banding is a fluorescent pattern obtained using quinacrine for staining. The pattern of bands is very similar to that seen in G-banding.

A typically, amniocentesis is performed at 16-20 weeks gestational age... interphase or metaphase chromosomes using fluorescence microscopy. This is found under the subject Explaination of Cytogentic Tests: http://www.slh.wisc.edu/cytogenetics/tests/explanation.php

Amniocentesis is a common prenatal test in which a small sample of the amniotic fluid surrounding the fetus is removed and examined. It was first used in 1882 to remove excess amniotic fluid, and has long been performed in late pregnancy to assess anemia in babies with Rh disease and to find out if the fetal lungs are mature enough for the baby to be delivered. Today, amniocentesis often is used in the second trimester of pregnancy (usually 15 to 18 weeks after a woman’s last menstrual period) to diagnose or, far more likely, rule out certain birth defects.

Amniocentesis is the most common prenatal test used to diagnose chromosomal and genetic birth defects. Another prenatal test, called chorionic villus sampling (CVS), can diagnose most, but not all, of the same birth defects as amniocentesis. CVS is done earlier in pregnancy (usually between 10 and 12 weeks) than amniocentesis, but appears to pose a slightly higher risk of miscarriage and other complications. Some studies also suggest that CVS may pose an extremely small risk of birth defects involving the fingers and toes.

Answer 3

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Answer 4

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Answer 5

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