Site of Antidiuretic hormone (ADH) action is:

 # Site of Antidiuretic hormone (ADH) action is:

A. Proximal tubule

B. Loop of Henle

C. Vasa recta

D. Collecting tubule

The correct answer is D. Collecting tubule.

Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then travels down the axon terminating in the posterior pituitary, and is released from vesicles into the circulation in response to extracellular fluid hypertonicity (hyperosmolality). AVP has two primary functions. First, it increases the amount of solute-free water reabsorbed back into the circulation from the filtrate in the kidney tubules of the nephrons. Second, AVP constricts arterioles, which increases peripheral vascular resistance and raises arterial blood pressure.

Acute increase of sodium absorption across the ascending loop of Henle. This adds to the countercurrent multiplication which aids in proper water reabsorption later in the distal tubule and collecting duct.

Pyruvate dehydrogenase complex contains all EXCEPT:

 # Pyruvate dehydrogenase complex contains all EXCEPT:

A. Biotin

B. NAD

C. FAD

D. Co-A

The correct answer is A. Biotin.

Pyruvate dehydrogenase complex (PDC) is a complex of three enzymes that converts pyruvate into acetyl-CoA by a process called pyruvate decarboxylation. Acetyl-CoA may then be used in the citric acid cycle to carry out cellular respiration, and this complex links the glycolysis metabolic pathway to the citric acid cycle. Pyruvate decarboxylation is also known as the "pyruvate dehydrogenase reaction" because it also involves the oxidation of pyruvate.

The enzymes involved in PDC are Pyruvate dehydrogenase (E1), Dihydrolipoyl transacetylase (E2), and Dihydrolipoyl dehydrogenase (E3). The cofactors involved are: TPP (thiamine pyrophosphate), magnesium, lipoate, coenzyme A, FAD and NAD+. 

Reference: https://en.wikipedia.org/wiki/Pyruvate_dehydrogenase_complex

The benign neoplasm of ‘brown fat’ noted in oral/pharyngeal region is:

 # The benign neoplasm of ‘brown fat’ noted in oral/pharyngeal region is:

A. Lipoma

B. Hibernoma

C. Teratoma

D. Brown tumor

The correct answer is B. Hibernoma. 

Hibernomas are uncommon neoplasms of brown adipose tissue. The most frequent sites of occurrence include the thigh, shoulder, and back. Less common myxoid and spindle cell hibernoma variants are likely to be located in the posterior neck and shoulder. Hibernomas are benign lipomatous neoplasms and have no potential for malignant transformation.  Hibernomas contain brown fat, and the name was coined about the presence of brown fat in hibernating animals. First described by Merkel 1906, these tumors are similar to lipomas in clinical behavior but have unique imaging and histopathologic features. Hibernomas generally present in young adults with a mean age of 38. In summary, these tumors are:

• Composed of brown fat
• Represent benign neoplasms
• Generally well-circumscribed masses
• Generally are small in size
• Exhibit slow growth
• Histopathologically composed of brown fat cells
• Chief differential diagnosis include well-differentiated liposarcomas (WDLS)
• Most often involve the thigh, trunk, and chest.
• Rare locations seen in less than 10% of cases include retroperitoneal, thorax, and intraabdominal regions.
• Fewer than 20% are intramuscular in location.

Reference: Tafti D, Cecava ND. Hibernoma. [Updated 2023 May 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK570579/

SNA angle describes the relationship of the:

 # SNA angle describes the relationship of the:

A. Maxilla to the cranial base

B. Mandible to the cranial base

C. Maxilla to mandible

D. Maxilla to the upper incisors

The correct answer is A. Maxilla to the cranial base. 

SNA: the angle between the sella/nasion plane and the nasion/A plane (normal value at the end of growth 82 ± 2°). This angle assesses the antero-posterior position of the maxilla relative to the upper cranial structures.

Analysis of skull shape and size, supraorbital ridge, extension of zygomatic arch beyond external meatus, measurement of angle of mandible helps in:

 # Analysis of skull shape and size, supraorbital ridge, extension of zygomatic arch beyond external meatus, measurement of angle of mandible helps in:

A. Sex determination

B. Racial determination

C. Age determination

D. Ethnicity determination

The correct answer is A. Sex determination.

Skull and facial features like mastoid process, supraorbital ridges, size and architecture of skull can help in determining the sex of patient in 94% cases. 

Sex differentiation (Sexing) of a specimen: It can be done using methods as below: 

 Using craniofacial morphology: The following 6 traits give accurate results 94% times: 

- Mastoid process 

- Supraorbital ridge \

- Size and architecture of skull 

- Extension of the zygomatic arch beyond the external auditory canal 

- Nasal aperture and 

- Gonial angle (on the mandible) (Including more features increases accuracy by 2%) 

Prolonged retention is usually needed in:

 # Prolonged retention is usually needed in:

A. Diastema

B. Mild crowding

C. Anterior cross bite

D. Deep bite

The correct answer is A. Diastema.

Fixed (bonded) orthodontic retainers are normally used where intra-arch instability is anticipated and prolonged retention is planned. There are three major indications:

• Maintenance of lower incisor position during late growth

• Diastema maintenance

• Maintenance of posterior tooth position in adults

Reference: Proffit's Contemporary Orthodontics, 6th Edition.

Root shape before and after orthodontic treatment with radiographic evidence was first given by:

 # Root shape before and after orthodontic treatment with radiographic evidence was first given by:

A. Kaley and Phillip

B. Newman and Proffit

C. Ketcham AH

D. Malmgren and Lavendar

The correct answer is C. Ketcham AH.

Albert H. Ketcham was born on August 3, 1870, and grew up in Whiting, Vermont. He graduated from the Boston Dental School in 1892, then moved to Colorado due to ill health. Inspired by the challenges

of the young profession of orthodontics, he chose to enter the Angle School of Orthodontia in 1902. As a deep thinker with an inquiring mind, Ketcham explored many of the philosophical and mechanical

problems, as well as the controversies of the profession of his day. He was one of the first to investigate root resorption, which continues to be a challenge today. He began to question some of Angle’s arbitrary pronouncements, causing Angle to attack him vehemently as a deviationist. He was smart enough to travel his own way from that time on. He worked hard to improve the American Society of Orthodontists (ASO) and served as their president in 1929. He was also instrumental in founding the American Board of Orthodontists (ABO), serving as its first president. In recognizing his lifetime of service, the Albert H. Ketcham Memorial is made to the individual member annually in recognition

of contributions made to the art and science of orthodontics. This award was meant to perpetuate and inspire the member as a leader in orthodontics following the example set by Dr. Ketcham. 

He pioneered dental radiography and was the first US orthodontist to install an x-ray laboratory. He delivered the first paper on x-rays in orthodontics to the American Society of Orthodontists in 1910. In 1926 he presented the first comprehensive data on root resorption.46 Although the earliest mention of root resorption in permanent teeth goes back to 1856, it was a report by Ketcham in 1927 (followed by a second in 1929) that finally aroused the concern of orthodontists.

Reference: ORTHODONTICS Current Principles and Techniques, Lee W. Graber, 7th Edition.