Block 7 Problem Quest

Human chorionic gonadotropin interacts with the LHCG receptor and promotes the maintenance of the corpus luteum during the beginning of pregnancy, causing it to secrete the hormone progesterone. Progesterone enriches the uterus with a thick lining of blood vessels and capillaries so that it can sustain the growing fetus. Due to its highly-negative charge, hCG may repel the immune cells of the mother, protecting the fetus during the first trimester. It has also been hypothesized that hCG may be a placental link for the development of local maternal immunotolerance. For example, hCG-treated endometrial cells induce an increase in T cell apoptosis (dissolution of T cells). These results suggest that hCG may be a link in the development of peritrophoblastic immune tolerance, and may facilitate the trophoblast invasion, which is known to expedite fetal development in the endometrium. It has also been suggested that hCG levels are linked to the severity of morning sickness in pregnant women.
Because of its similarity to LH, hCG can also be used clinically to induce ovulation in the ovaries as well as testosterone production in the testes. As the most abundant biological source is women who are presently pregnant, some organizations collect urine from pregnant women to extract hCG for use in fertility treatment.[10]
Human chorionic gonadotropin also plays a role in cellular differentiation/proliferation and may activate apoptosis
Human chorionic gonadotropin (hCG) is a hormone produced during pregnancy that is made by the developing embryo after conception, and later by the placental component syncytiotrophoblast. Some cancerous tumors produce this hormone; therefore, elevated levels measured when the patient is not pregnant can lead to a cancer diagnosis. However, it is not known whether this production is a contributing cause or an effect of tumorigenesis. The pituitary analog of hCG, known as luteinizing hormone (LH), is produced in the pituitary gland of males and females of all ages.

Normally, before ovulation, the corpus luteum produces only estrogen to prepare the uterus. After ovulation, the corpus luteum normally produces both estrogen and progesterone. If pregnancy occurs, human chorianic gonadotropin (HCG) from the placenta prevents the corpus luteum from atrophy. If pregnancy doesn't occur, the corpus luteum simply regresses and estrogen and progesterone production drop. In the anovulatory cycle, the corpus luteum continues to produce estrogen. This continued bath in estrogen causes the symptoms of menometrorrhagia (excessive bleeding at irregular intervals).

LH stimulation causes the granulosa cells to produce and secrete progesterone. Progesterone plays a crucial role in the ovulation process, including the maturation and release of the dominant follicle. It helps prepare the uterus for potential implantation of a fertilized egg and supports the development of the endometrium. Therefore, the secretion of progesterone by the granulosa cells in response to LH stimulation is necessary for ovulation of the dominant follicle.

The correct answer is that the zona pellucida found in the secondary follicle is composed of GAGs and glycoproteins. The zona pellucida is a thick layer that surrounds the oocyte and plays a crucial role in fertilization. It helps to protect the oocyte and facilitate sperm binding and penetration. It is primarily composed of glycosaminoglycans (GAGs) and glycoproteins, which provide structural support and aid in the interaction between the oocyte and sperm.

Blocking the GnRH receptor will result in decreased production of LH and FSH,
which will subsequently inhibit growth of the dominant follicle. Interestingly, you could also suppress follicle growth and development by administering receptor antagonists designed to inhibit FSH receptor pathway or the LH receptor pathway, but the best answer is a GnRH antagonist that blocks both
LH and FSH activity. Recall the 2‐cell theory of steroidogenesis, and how LH and FSH action on the theca and granulosa cells is a complementary system that results in estradiol production.

A fully functional placenta begins to secrete increasing concentrations of estriol
at approximately 8 weeks of pregnancy. The rise in estriol indicates that the maternal‐fetal‐placental unit is fully functional. Therefore, the rise in estriol is associated with the luteal‐placental shift, which typically occurs between 7‐9 weeks of gestation. The other four major events occur within the first 2 weeks of pregnancy and are not associated with estriol.

All three estrogens are secreted in large amounts and (estrone, estradiol,
estriol) act as vasodilators to increase blood flow to the uterus and growing placenta. Estriol is synthesized by the fully functional placenta after the luteal‐placental steroidogenic shift, and is considered the estrogen of pregnancy. Additional roles of estrogen during pregnancy are being examined, but to date, remain largely unknown.

Luteinizing hormone (LH) works directly on the interstitial cells of Leydig (i.e.
Leydig cells) to stimulate the production of testosterone. Low levels of LH can result in decreased levels of testosterone,
which can subsequently lead to decreased sperm production. Remember that LH acts directly on the Leydig cells, and
then the testosterone generated within the Leydig cells acts on the Sertoli cells to regulate spermatogenesis Prolonged
exposure to low levels of testosterone can also lead to systemic effects, such as decreased muscle mass and/or lethargy.
Evaluating the levels of DHT and FSH would also be beneficial, since levels of DHT are directly correlated with levels of
testosterone and FSH is also required by the Sertoli cells during the process of spermatogenesis. Additionally, checking
the levels of prolactin could be informative, since prolactin helps stimulate the expression of the LH receptors.
However, in this particular case the PCP suspects a problem with testosterone production and/or secretion, and
therefore the first step is to directly measure serum levels of testosterone and LH.

To assure the rapid loss of c-Fos and c-Myc after their induction in normal cells, both proteins and their corresponding mRNAs are intrinsically unstable. Some of the changes that turn c-fos from a normal gene to an oncogene involve loss of sequences in the gene that make the Fos mRNA and protein short-lived. Conversion of the c-myc proto-oncogene into an oncogene can occur by several different mechanisms. In cells of the human tumor known as Burkitt’s lymphoma, the c-myc gene is translocated to a site near the heavy-chain antibody genes. An analogous transloca- tion in the mouse genome is also involved in mouse myelomas. In both cases, the tumor cells arise from antibody-producing cells, which carry out DNA rearrangements during their maturation. The c-myc translocation is a rare aberration of the normal rearrangement events, bringing it from its normal, distant chromosomal location into juxtaposition with the enhancer of the antibody genes. The translocated myc gene, now regulated by the antibody enhancer, is continually expressed, causing the cell to become cancerous. Localized reduplication of a segment of DNA containing the myc gene, which occurs in several human tumors, also causes inappropriately high expression of the otherwise normal Myc protein.

Based on the pedigree, individual 11-2 is a carrier of the cystic fibrosis gene. Since cystic fibrosis is an autosomal recessive disorder, for individual 11-2 to have an affected child, they would need to have a child with another carrier or an individual with cystic fibrosis. The risk of having a child with cystic fibrosis is 1/4 if both parents are carriers. Therefore, the risk that individual 11-2 will have an affected child is 1/4 multiplied by the probability of the other parent being a carrier, which is 1/4 as well. This results in a risk of 1/16. Given a prevalence of 2500 individuals, the risk can be calculated as 1/2500 multiplied by 1/16, which simplifies to 1/40000. This is approximately equal to 1/100, so the answer is 1/100.

The correct answer is shared environment. This is because the theory suggests that the socioeconomic status of the family, which is a part of the shared environment, plays a significant role in determining a child's intelligence. The shared environment refers to the environmental factors that are common to individuals in the same family or household, such as parenting style, education, and socioeconomic conditions.

The most likely explanation for the contraceptive action of the oral contraceptive pill containing synthetic progestin is inadequate decidualization of the uterus. This means that the lining of the uterus does not properly develop and thicken, making it less suitable for implantation of a fertilized egg. This prevents pregnancy from occurring.

Granulosa‐lutein cells (GLC) and theca‐lutein cells (TLC) both express
functional LH receptors, and the GLC secrete progesterone and estrogen whereas the TLC secrete androgen
(predominantly androstenedione) and progesterone. The GLC then aromatize the androgen into estrogen. These cells
types can also be distinguished histologically, since the TLC express high levels of CYP17 (the enzyme required to convert
progesterone into androgen) whereas the GLC express CYP19 (aromatase, required to convert androgen into estrogen).
Remember that the primary function of the CL is to secrete progesterone.
Steroidogenesis Summary:
Granulosa cells = estrogen during the follicular phase
Granulosa cells = estrogens and progesterone during the ovulatory window (after they acquire the LH
receptor)
Granulosa-lutein cells = progesterone and estrogen during the luteal phase
Theca cells = androgens
Theca-lutein cells = androgens and subsidiary amounts of progesterone
hCG = binds to the LH receptor and therefore maintains luteal steroidogenesis resulting in continued
progesterone production
The CL predominantly secretes progesterone. Follicles predominantly secrete estrogen.

This woman may be experiencing peri‐menopause, but nausea is not a typical
symptom associated with menopause. The history of no menstrual period for 3 months and onset of nausea is
indicative of pregnancy, likely the end of the first trimester. An hCG test will quickly determine pregnancy status. The
woman is worried about menopause, but as a physician you need to look at the entire picture. Additionally, you are
told in the first sentence that the woman is in a "monogamous relationship", therefore in this instance you should
assume the woman is engaged in sexual activity.
Estrone is considered the estrogen of menopause, but in this case, it would be prudent to evaluate progesterone and
estradiol levels to first determine cyclicity. If estradiol levels are normal, then the woman may have an underlying
pathophysiological disorder, such as PCOS or leiomyoma (uterine fibroids). Reproductive pathophysiological disorders
will be covered in detail in Semester 4.

The most likely explanation for the occurrence of Duchenne muscular dystrophy (DMD) in a boy with no family history of the disease is a recombination event in the dystrophin gene that caused a frameshift mutation. This frameshift mutation would result in an untranslatable mRNA, leading to the absence of functional dystrophin protein. This explanation suggests that the boy inherited the mutation from his parents through a recombination event during gamete formation, rather than through a known familial genetic mutation.

 Prevalence 1 in 4000 in males and 1 in 8000 in females
 FRM1 gene encodes for a RNA-binding protein termed FMRP that is expressed in many cells including neurons. Loss of function mutation
 99% of the FRM1 mutations are due to expansions of a (CGG)n repeat located at the 5’ end of the gene CGG Repeat expansion
(slide 17- trinuc repts-Blanch)

Glutamic acid is not a hormone or neurotransmitter involved in the initiation of follicular development. The correct answer should be GnRH (Gonadotropin-releasing hormone). GnRH is released from the hypothalamus and stimulates the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland, which then initiate follicular development.

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The most likely diagnosis for the 4-week old male with severe jaundice, high indirect bilirubin, low fecal urobilinogen, and slight hepatomegaly is Uridyl glucuronyl transferase deficiency. This condition is also known as Crigler-Najjar syndrome, which is a rare genetic disorder characterized by the absence or deficiency of the enzyme uridyl glucuronyl transferase. This enzyme is responsible for conjugating bilirubin, a waste product of red blood cell breakdown, making it water-soluble and allowing it to be excreted in the bile. Without this enzyme, bilirubin levels become elevated, leading to jaundice.

The correct answer is Purine nucleoside phosphorylase. This is because the patient's symptoms, such as recurrent infections, failure to thrive, developmental delay, and lack of peripheral lymphoid tissue, are characteristic of purine nucleoside phosphorylase deficiency, also known as PNP deficiency. PNP is an enzyme involved in the purine salvage pathway, which recycles purine nucleosides. Without PNP, there is a buildup of toxic metabolites, leading to immunodeficiency and other symptoms seen in the patient.

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The torn sacrospinous ligament is located in the pelvis, and it provides support to the pelvic organs. The coccygeus muscle is also located in the pelvis, and it attaches to the sacrospinous ligament. Therefore, if the sacrospinous ligament is torn, it is likely that the coccygeus muscle will also be affected. The pudendal nerve is responsible for innervating the muscles of the pelvic floor, including the coccygeus muscle. Therefore, if the sacrospinous ligament is torn, it is possible that the pudendal nerve may also be compromised.

The best explanation for her amenorrhea is the absence of a surge in luteinizing hormone. This is likely due to her intense training regimen for the marathon and the resulting weight loss. Intense exercise and significant weight loss can disrupt the hormonal balance in the body, leading to the suppression of luteinizing hormone, which is necessary for ovulation and the menstrual cycle.

Activin is a hormone that plays a role in the development of ovarian follicles. It stimulates the proliferation of the follicular layer, which leads to the formation of the granulosa layer in the multilaminar primary follicle. This is an important step in the maturation of the follicle and the eventual release of an egg during ovulation. FSH and LH also play important roles in the hormonal interplay on the ovary, but the statement about Activin is the only correct one among the given options.

The deep layer of fascia in the pelvis and perineum contains the external spermatic fascia and dartos fascia. These fascial layers are continuous with the abdominal fascial layers. The external spermatic fascia surrounds the spermatic cord and testes, providing support and protection. Dartos fascia is a smooth muscle layer that is responsible for the wrinkling of the scrotum. Both of these fascial layers are found in the deep layer of fascia in the pelvis and perineum.