Dear Colleagues

Hello

In this issue , we are discussing one topic which correlate with chromosomal abnormalities and pregnancy loss. These losses are mainly first trimester losses. Based upon several studies world wide, in which 7182 miscarriages were successfully cytogenetically analyzed using banding techniques, it has been found that nearly 50% of spontaneous abortions in the general reproductive population were cytogenetically abnormal. Trisomies accounted for 56%, polyploidy 20%, monosomy X 18%, translocation 4% and others accounted for 2% of these cytogenetically abnormal miscarriages. The most common of the trisomy was trisomy 16,which accounted for approximately one-third of all trisomies. Fortunately, all trisomic 16 embryos end in spontaneous abortion. Only embryos with trisomy 21,18,and 13 have been reported to survive to birth, although the probability of this is low, i.e., 22.1%, 5.4% and 2.8%, respectively. Sex chromosome trisomies, i.e., XXY, XXX, XYY, have higher chances of survival of 55%, 70% and 100% respectively

We had our journal club this time; the topic of discussion was “ Pre-eclampsia and eclampsia, Anesthesiologist’s view point, by Dr. Shailendra Singh Chouhan, a leading anesthesiologist of our town.

We are putting our summer course in details. It is useful for the students of biotechnology and the doctors who practice fetal medicine

With best wishes

Dr.D’Pankar Banerji

1.Chromosome abnormalities and Pregnancy loss

For a long time it was difficult to detect the early stages o pregnancy with certainty. It was thus possible for a woman to become pregnancy but to lose the embryo before knowing of the pregnancy. Sensitive urinary assays of chorionic gonadotropin levels, which increase when the embryo implants in the uterine wall, have allowed researchers to pinpoint accurately the occurrence of pregnancy at this early stage. Follow-up of women in whom implantation was verified in this way has shown that about one third of pregnancies are lost after implantation (the number lost before implantation is unknown). Therefore, spontaneous pregnancy loss is common the human.

Chromosome abnormities are the leading known cause of pregnancy loss. It is estimated tat a minimum of 10% to 15% of conceptions have a chromosome abnormality. At least 95% of these chromosomally abnormal conceptions are lost before term. Karyotype studies o miscarriages indicate that about 50% of the chromosome abnormalities are trisomies, 20% are monosomies, 15% are triploids and remainder consists of tetraploids and structural abnormalities. Some chromosome abnormalities that are common at conception seldom or never survive to term. For example, trisomy 16 is thought to be the most common trisomy at conception, but it is never seen in live births.

It is possible to study chromosome abnormalities directly in sperm and egg cells. Oocyte are typically obtained form unused material in in-vitro fertilization studies. Karyotype obtained from these cells indicates that 20% to 25% of oocytes have missing or extra chromosome (this may be an underestimate, because the oocyte’s chromosomes are difficult to visualize and count). Human sperm cells can be studied after fusing them with hamster oocyte so that their DNA begins mitosis and condenses, allowing easier visualization. The frequency of aneuploidy in these sperm cells is about 3% to 4%. Structural abnormalities are seen in about 5% of sperm cells and about 1% of oocytes (it is noteworthy that structural abnormalities increase with advanced paternal age). Undoubtedly, this high rate of chromosome abnormality contributes importantly to later pregnancy loss.

These approaches, while informative, may involve some biases. For example. Mother in whom in-vitro fertilization is performed is not a representative sample of the population. In addition, their oocytes have been stimulated artificially, and only those oocytes that could not be fertilized by sperms are studied. Thus, the oocytes themselves may not be a representative sample. Thus, the oocytes themselves may not be a representative sample. The sperm cells studied in human-hamster hybrids represent only those that are capable of penetrating the hamster oocyte and again may not be representative sample

Missing or extra chromosome in human sperm cells May also been detected using FISH. This approach can evaluate thousands of cells fairly rapidly. Giving it an important advantage over the human-hamster technique. In general, the FISH studies have yielded results similar to those of the human-hamster studies, showing that, on average, the frequency of disomy is approximately 0.15% for each autosome and 0.26% for the sex chromosomes. These studies have also confirmed a tendency for elevated frequencies of nondisjunction of the sex chromosomes and some of the acrocentric chromosomes, including chromosome 21, in sperm cells.

In short: Pregnancy loss is common humans, with approximately on third of pregnancies lost spontaneously after implantation. Chromosome abnormalities, which have been studied in sperm and egg cells and in miscarriages and stillbirths, are important cause of pregnancy loss.

2.SUMMER COURSE PROGRAM

For Biotechnology

9^th June 2009-19^th June2009  :Time 8.00am-1.00pm
 

DAY 1

THEORY :

1.       Introduction to cell biology

2.       Microscopy

PRACTICAL:

      Microscopy :Stereozoom, Trinocular photomicrography, Inverted Microscopy

DAY 2

THEORY

1.       Cell cycle and cell division

2.       Primary tissue culture, introduction to tissue culture

PRACTICAL:

      Culture media preparation for tissue culture

DAY 3

THEORY

1.       Detection and measurement of genetic variation

2.       Monohybrid/dihybrid, mutations, Mendelian genetics

PRACTICAL

             Planting

DAY 4

THEORY

1.       Replication

2.       Transcription and translation

PRACTICAL

       DNA isolation from blood 

DAY 5

THEORY

1.       ovulation induction for in vitro fertilization

2.       Human ,genetic diseases

PRACTICAL

         PCR demonstration

DAY 6

THEORY

1.       Embryo biotechnology and stem cells

PRACTICAL

       1.Hands on retrieval of mammalian eggs under stereomicroscope

        2.in-vitro maturation of oocyte

DAY 7

PRACTICAL

Harvesting of culture

In-vitro maturation of oocytes

DAY 8

THEORY

1.Single Gene disorders

 PRACTICAL

          Cryopreservation of Spermatozoa and oocytes

DAY 9

Theory

      1.Immunogenetics,basic

PRACTICAL

    Banding / slide preparation /identification of chromosomes harvested earlier

DAY 10

Seminar by the participants

Certificate distribution