The cells in the testes that secrete testosterone are the Leydig cells.Other cells in testes include:- Spermatogonia: These are undifferentiated male germ cells which undergo spermatogenesis in the seminiferous tubules of the testes.- Sertoli cells: They are a part of the seminiferous tubule of the testes, cells are activated by FSH and nourish developing sperm cells.- Myoid: They are squamous contractile cells which generate peristaltic waves, they surround the basement membrane of testes.- Fibroblasts: Cells which synthesise collagen and the extracellular matrix.

Jaundice is considered pathologic if it presents within the first 24 hours after birth. Although up to 60 percent of term new-borns have clinical jaundice in the first week of life, few have significant underlying disease.1,2 However, hyperbilirubinemia in the new-born period can be associated with severe illnesses such as haemolytic disease, metabolic and endocrine disorders, anatomic abnormalities of the liver, and infections. The risk factors here is the mothers blood ground which suggests the cause is fetal-maternal blood group incompatibility.

Correlation is a bivariate analysis that measures the strength of association between two variables and the direction of the relationship.Pearson r correlation: Pearson r correlation is the most widely used correlation statistic to measure the degree of the relationship between linearly related variables. Pearson’s correlation coefficient is the test that measures the statistical relationship, or association, between two continuous variables. It is known as the best method of measuring the association between variables of interest because it is based on the method of covariance. It gives information about the magnitude of the association, or correlation, as well as the direction of the relationship.The non-parametric Spearman or Kendall rank correlation coefficient is used if neither variable has a normal distribution or the sample size is small (i.e. <20).

Precocious puberty is the attainment of normal pubertal biochemical and physical features at an abnormally early age. The age cut-offs commonly used to define precocious puberty are 8 years for females and 9 years for males. Precocious puberty may be central (true) or peripheral (false) based on the aetiology. Central precocious puberty is due to the premature activation of the hypothalamic-pituitary-gonadal axis, which in turn leads to the development of secondary sexual characteristics at an earlier than usual age. The best laboratory investigation to diagnose central precocious puberty is a gonadotropin-releasing hormone stimulation test, which is regarded as the gold standard. It requires the collection of multiple blood samples at different time points to measure FSH and LH levels. If the LH levels increase to >8IU/L after stimulation with GnRH, then the diagnosis of central precocious puberty is confirmed.

The injury described in question leads to an abnormal communication between the orbit and the ipsilateral maxillary sinus – this is termed as a blow-out fracture of the orbit.The maxillary sinuses are found in the maxillary bone, inferior to the orbit. They are the largest of the paranasal air sinuses. The maxillary bone forms the floor of the orbit. This layer of bone separates the orbit from the maxillary sinus. As such, fractures of the floor of the orbit can be associated with herniation of the orbital contents into the maxillary sinus. Other options:- The ethmoidal air cells are a collection of smaller air cells in the ethmoid bone. They lie lateral to the anterior superior nasal cavity. They are separated from the orbit by a very thin plate of ethmoid bone called the lamina papyracea, which is found on the medial wall of the orbit. The thin nature of this bone means it is commonly fractured in orbital trauma. However, this is the incorrect answer to the above question as a communication between the ethmoidal air cells, and the orbit is associated with fractures of the medial wall of the orbit, not the floor. – The frontal sinuses are found in the frontal bones, above the orbits on each side of the head. A large portion of the roof of the orbit is composed of the frontal bone and separates the orbit from the frontal sinus. Fractures of the roof of the orbit can be associated with communication between the frontal sinus and orbit. The frontal bones are strong, and so fracture is associated with high-impact anterior trauma, such as a road traffic accident. – The sphenoid sinuses are found in the posterior portion of the roof of the nasal cavity. The pituitary gland lies nestled within the hypophyseal fossa, with only a thin wall of bone separating it from the sphenoid sinus below. As such, neurosurgeons can gain access to the pituitary gland via the sphenoid sinus, in a procedure called transsphenoidal hypophysectomy. – The nasal cavity extends from the nares to the nasopharynx. It is found more medial and inferior than the orbits. It does not lie adjacent to the orbit at any point and so is unlikely to be involved in an orbital fracture.

The initial symptoms of spasmodic abdominal pain, rectal bleeding and vomiting might point towards intussusception, but the peak incidence is in children aged 6-9 months. Considering that this child has additional symptoms of haematuria, proteinuria and a purpuric rash, it is more likely that the child has Henoch-Schonlein purpura (HSP). HSP is an identifiable cause of intussusception. It is an IgA-mediated, autoimmune hypersensitivity vasculitis that targets the small vessels of the skin, GI tract, kidneys, and joints. It is most commonly seen in children aged 3 – 6years and is twice as common in boys than girls. Preceding viral URTI with low-grade pyrexia is common. The most common organism associated with HSP is, however, Group A streptococcal infection. A purpuric rash is seen on the back of the legs and buttocks and can less frequently, affect the arms. Arthralgia is common (usually knees/ankles) in these patients. Abdominal pain and bloody diarrhoea may occur. And half of the children with HSP have renal involvement. Rarely, it can lead to end-stage renal failure. Treatment includes adequate hydration, occasionally steroids, and other immunosuppressants. The disease can recur in 1 in 3 children.

The paired sample t-test, sometimes called the dependent sample t-test, is a statistical procedure used to determine whether the mean difference between two sets of observations is zero. In a paired sample t-test, each subject or entity is measured twice, resulting in pairs of observations. Common applications of the paired sample t-test include case-control studies or repeated-measures designs.Statistical significance is determined by looking at the p-value. The p-value gives the probability of observing the test results under the null hypothesis. The lower the p-value, the lower the probability of obtaining a result like the one that was observed if the null hypothesis was true. Thus, a low p-value indicates decreased support for the null hypothesis. However, the possibility that the null hypothesis is true and that we simply obtained a very rare result can never be ruled out completely. The cut-off value for determining statistical significance is ultimately decided on by the researcher, but usually a value of .05 or less is chosen. This corresponds to a 5% (or less) chance of obtaining a result like the one that was observed if the null hypothesis was true.

Based on the clinical scenario, the most likely risk factor in this child to develop gallstones is sickle cell disease.Note:Haemolysis is the most frequent cause for gallstones in children and the likeliest cause because of his ethnicity would be sickle cell disease. The gallstones are pigmented which form from bilirubin. 70% of patients with sickle cell disease will develop gallstones; the prevalence of gallstones is related to the rate of haemolysis.Other options:- Gilbert’s syndrome: it is a common condition in which bilirubin glucuronidation (i.e. converting bilirubin into a water-soluble form) is affected. During times of stress (viral illness, fasting, etc.) there is an excess bilirubin production, and jaundice may develop. It is a benign condition but there is some evidence of an increased risk of developing gallstones. However, sickle cell disease is a more likely risk factor in this case.- Hereditary spherocytosis: Hereditary spherocytosis is a disease of the white population and is less likely to be the underlying cause in this case.- Male gender: After puberty, the incidence of gallstones is higher in women. Before puberty, the incidence is equal.- Obesity: Obesity is a risk factor for gallstones and is thought to be behind the rising incidence among young adults. Nevertheless, haemolytic states remain the most common reason for gallstones in children.

The swelling and bruising on the mandible needs to be checked for fractures. A facial X-ray can adequately visualize this.

Transient tachypnoea of the new-born (TTN) is the commonest cause of respiratory distress in new-borns and self-limiting. It can affect any new-born shortly after birth. Its most prominent feature is tachypnoea. Nasal flaring, grunting, or intercostal retractions may also be present.

Answer: Undertake a laparotomyIntussusception, which is defined as the telescoping or invagination of a proximal portion of intestine (intussusceptum) into a more distal portion (intussuscipiens), is one of the most common causes of bowel obstruction in infants and toddlers.Intussusception may be ileoileal, colocolic, ileoileocolic, or ileocolic (the most common type).Most infants with intussusception have a history of intermittent severe cramping or colicky abdominal pain, occurring every 5-30 minutes. During these attacks, the infant screams and flexes at the waist, draws the legs up to the abdomen, and may appear pale. These episodes may last for only a few seconds and are separated by periods of calm normal appearance and activity. However, some infants become quite lethargic and somnolent between attacks.Infants with intussusception require surgical correction. Prompt laparotomy following diagnosis is crucial for achieving better outcomes. Primary anastomosis can be performed successfully, and stomas can be created in the critically ill patients or those with late detection and septicaemia.

The average amount of energy required by a well preterm baby in a thermo-neutral environment is 50/kcal/kg to maintain essential body functions while it takes about 70 kcal/kg/day for optimal growth. It is important to ensure that enough proteins are given per calorie to limit catabolism and promote cell building. Caloric need usually increases when the baby is ill.

The main problem with infants having gastroenteritis is dehydration. So they should be admitted to the hospital for IV fluids if they are not tolerating oral fluids.

Psoriasis is a chronic inflammatory skin disease that is mainly due to the interplay between keratinocytes, dermal vascular cells, and antigen-presenting cells. There are five main types of psoriasis based on the type and severity of the lesions it produces. A useful tool to determine the extent and severity of psoriasis is the Psoriasis Area and Severity Index (PASI) score, which takes into account the percentage of a specific area affected by psoriasis in combination with severity, which in turn is assessed by the presence of desquamation, induration, and erythema.

Coverings of the spermatic cord:Spermatic cord is covered by three concentric layers of fasciae, derived from the layers the of anterior abdominal wall. Developmentally, each covering is acquired as the processus vaginalis descends into the scrotum through the layers of the abdominal wall. The layers are:External spermatic fascia: It is derived from the external oblique muscle. It attaches to the margins of superficial inguinal ring.Cremasteric fascia: It is derived from the internal oblique muscle. It covers the cremaster muscle.Internal spermatic fascia: It is derived from the fascia transversalis (fascia covering the transversus abdominis muscle). It is attached to the margins of the deep inguinal ring.

The gastrocolic reflex is a physiological reflex that involves increase in colonic motility in response to stretch in the stomach and by-products of digestion in the small intestine. It is shown to be uneven in its distribution throughout the colon, with the sigmoid colon affected more than the right side of the colon in terms of a phasic response. Various neuropeptides have been proposed as mediators of this reflex, such as serotonin, neurotensin, cholecystokinin and gastrin.

At the age of 18 months, Gertrude should be able to follow a one step command. At this age she would also be capable of putting words together in 1 or 2 word phrases, scribbling, throwing a ball, and building a tower of four cubes. At 2 she should be able to feed herself with a spoon or a fork, copy a vertical line, ride a tricycle, kick a ball and balance on one foot. Activities such as jumping will follow later on in her development at 3 years.

Gilbert’s syndrome is an autosomal recessive condition that results from defective bilirubin conjugation due to a deficiency of UDP glucuronyl transferase – 1. The prevalence is approximately 1-2% in the general population.The clinical presentation of Gilbert’s syndrome include:- Unconjugated hyperbilinaemia- Jaundice can occur during an intercurrent illnessManagement:Blood investigations usually reveal a rise in bilirubin following prolonged fasting or intravenous nicotinic acid.No treatment required for these patients.Other options:- CYP2C9 deficiency causes reduced warfarin metabolism, and subsequent enhanced drug effects. – Pancreatic disease, cholestasis, excessive alcohol consumption and certain drugs are common causes of raised GGT levels- Defective hepatocyte excretion of conjugated bilirubin is related to the pathophysiology of Dubin-Johnson syndrome- Reduced CYP2C19 levels can lead to the disordered metabolism of clopidogrel and other drugs such as proton-pump inhibitors, anticonvulsants and sedatives.

Congenital TB symptoms typically develop during the second or third week of life and include poor feeding, poor weight gain, cough, lethargy, and irritability. Other symptoms include fever, ear discharge, and skin lesions.Signs of congenital TB include failure to thrive, icterus, hepatosplenomegaly, tachypnoea, and lymphadenopathy.

Before the test, the patient was likely to have the disease being tested for. Their pre test odds were 2, making them twice as likely to have the disease. After testing positive, their pretest odds of 2 and the likelihood ratio of 3 are multiplied to produce 6 as the post test odds. The patient is now 6 times as likely to have the disease after the test. Likelihood ratios above 10 or below 0.1 are strong evidence to rule in and rule out a diagnosis. The negative likelihood ratio is not known here, but does not subtract from the interpretation of the outcomes in this patient.

Except Tetralogy of Fallot, the others are acyanotic heart diseases. The cyanotic spells and loss of consciousness are due to spasm of the infundibular septum, which acutely worsens the right ventricular outflow tract obstruction. The given murmur is due to a ventricular septal defect.

The trisomy 18 syndrome, also known as Edwards syndrome, is a common chromosomal disorder due to the presence of an extra chromosome 18, either full, mosaic trisomy, or partial trisomy 18q. The condition is the second most common autosomal trisomy syndrome after trisomy 21.Currently, most cases of trisomy 18 are prenatally diagnosed, based on screening by maternal age, maternal serum marker screening, or detection of sonographic abnormalities (e.g., increased nuchal translucency thickness, growth retardation, choroid plexus cyst, overlapping of fingers, and congenital heart defects ).The main clinical features represent the clues for the diagnosis in the perinatal period and include prenatal growth deficiency, characteristic craniofacial features (dolichocephaly, short palpebral fissures, micrognathia external anomalies of the ears, and redundant skin at the back of the neck), distinctive hand posture (overriding fingers: index finger overlapping the third and 5th finger overlapping the 4th), nail hypoplasia, short hallux, underdeveloped thumbs, short sternum, and club feet and major malformations (particularly involving the heart).

The boy suffers from balanitis xerotica obliterans (BXO) which is surgically treated with circumcision and urethral calibration. In fact, the condition is the only true medical indication for circumcision.

Cranial nerve VI, also known as the abducent nerve, innervates the ipsilateral lateral rectus (LR), which functions to abduct the ipsilateral eye. Patients usually present with an isolated abduction deficit, binocular horizontal diplopia, worse in the distance, and esotropia in primary gaze. Patients also may present with a head-turn to maintain binocularity and binocular fusion and to minimize diplopiaExamination for a sixth nerve palsy involves documenting the presence or absence of papilledema, examining the ocular motility, evaluating the eyelids and pupils, and excluding involvement of other cranial nerves (e.g., V, VII, VIII).

The most probable cause for the patient’s presentation would be intra-abdominal adhesions, and the most appropriate management for this patient would be nasogastric decompression and intravenous fluids.Malrotation typically presents in the first month of life with bilious vomiting. There is a lifetime risk of intra-abdominal adhesions. This presents with bilious vomiting and dilated bowel loops on plain abdominal film. 2/3 of adhesional obstructions resolve by conservative management with nasogastric decompression and intravenous fluids. If this fails to resolve after 24-48 hours or if there are signs of peritonism, a laparotomy is indicated.Other options:- Recurrent volvulus, urgent laparotomy required: The child is now 8-years-old and recurrent volvulus is unlikely as bowel should be fixed by intra-abdominal adhesions.- Intra-abdominal adhesions, surgery for division of intra-abdominal adhesions: Although surgery may be required, the majority of adhesional obstructive cases respond to conservative management.- Gastroenteritis with incompetent pylorus, intravenous fluids: While it is true that patients with malrotation can have bilious vomiting in gastroenteritis, the abdominal X-ray is suggestive of obstruction.- Likely sepsis with bilious vomiting, intravenous fluids and antibiotics: While a septic ileus can give bilious vomiting, this patient has no inflammatory markers suggestive of sepsis.

Tuner’s syndrome is not associated with arachnodactyly.Arachnodactyly is seen in the following conditions:- Marfan syndrome- Homocystinuria- Ehlers-Danlos syndrome- Congenital contractural arachnodactylyOther rare syndromes include:- Loeys-Dietz syndrome- Antley-Bixler syndrome- Marden-Walker syndrome- Lujan-Frinz syndrome- Haim-Munk syndrome- Marden-Walker syndrome- Spondylocostal dysostosis

Lesch-Nyhan syndrome is a condition that occurs almost exclusively in males. This condition is inherited in an X-linked recessive pattern It is characterized by neurological and behavioural abnormalities and the overproduction of uric acid. Uric acid is a waste product of normal chemical processes and is found in blood and urine. Excess uric acid can be released from the blood and build up under the skin and cause gouty arthritis (arthritis caused by an accumulation of uric acid in the joints). Uric acid accumulation can also cause kidney and bladder stones.The nervous system and behavioural disturbances experienced by people with Lesch-Nyhan syndrome include abnormal involuntary muscle movements, such as tensing of various muscles (dystonia), jerking movements (chorea), and flailing of the limbs (ballismus). People with Lesch-Nyhan syndrome usually cannot walk, require assistance sitting, and generally use a wheelchair. Self-injury (including biting and head banging) is the most common and distinctive behavioural problem in individuals with Lesch-Nyhan syndrome.

Septic (infectious) arthritis is a bacterial infection of the joint space. Contamination occurs either via the bloodstream, iatrogenically, or by local extension (e.g., penetrating trauma). Patients with damaged (e.g., patients with rheumatoid arthritis) or prosthetic joints have an increased risk. Patients usually present with an acutely swollen, painful joint, limited range of motion, and a fever. Suspected infectious arthritis requires prompt arthrocentesis for diagnosis. In addition to the immediate broad-spectrum antibiotic therapy, surgical drainage and debridement may be necessary to prevent cartilage destruction and sepsis.

Transposition of the great arteries (TGA) is a common congenital heart lesion that presents with severe cyanosis that is likely to appear in the first day of life.

Based on the clinical scenario, the most probable diagnosis for this patient is maxillary sinusitis.The maxillary sinus drains from its superior aspect, leaving it prone to infections. It is the most commonly affected sinus in sinusitis.Common symptoms of maxillary sinusitis include postnasal discharge, pain, headache and toothache.Radiological imaging may show a fluid level in the antrum.Common organisms causing maxillary sinusitis include Haemophilus influenzae or Streptococcus pneumoniae.Treatment with antral lavage may facilitate diagnosis and relieve symptoms. Antimicrobial therapy has to be continued for long periods. Antrostomy may be needed.Other options:- Frontal sinusitis more commonly causes intracranial complications, but it is still less frequent than maxillary sinusitis.- The petrosal sinus is not a cavity within bone; rather, it is a venous structure located beneath the brain.- Frontoethmoidal sinusitis: It usually presents with frontal headache, nasal obstruction and altered sense of smell. Inflammation may progress to involve periorbital tissues. Ocular symptoms may occur, and secondary CNS involvement brought about by infection entering via emissary veins. CT scanning is the imaging modality of choice. Early cases may be managed with antibiotics. More severe cases usually require surgical drainage.