In the PCR, DNA amplification is performed by thermostable enzymes; invariably either family A DNA polymerases from thermophilic and hyperthermophilic Bacteria or family B DNA polymerases from hyperthermophilic Archaea. Family Y DNA polymerase from the hyperthermophilic archaeon Sulfolobus solfataricus, Sso-polY, is also an enzyme marketed for PCR, but with specialist applications. Each thermostable DNA polymerases has different characteristics and to achieve optimal results, the choice of a PCR enzyme depends on the application itself.

Huntington’s disease is an autosomal inherited condition characterized by progressive dementia and worsening choreiform movements. Symptoms typically appear between ages 30 and 50. Ultimately the weakened individual succumbs to pneumonia, heart failure, or other complications.

This case describes Zollinger-Ellison syndrome. It is characterized by refractory peptic ulcer disease, often multiple ulcers. This is typically caused by secretion of gastrin from a gastrinoma, a neuroendocrine tumour. The most common site of ulceration is the duodenum. A symptom of a pancreatic gastrinoma may be steatorrhea from hypersecretion of gastrin. Serum gastrin levels > 1000 and a pH < 2 are diagnostic of pancreatic gastrinoma. The secretin test is a test that can differentiate gastrinoma from other causes of high gastrin levels. Gastrin will rise after secretin injection if the patient has a gastrinoma.

A retrospective cohort study of the primary care records of 247 lung cancer patients diagnosed between 1998–2002 showed that 10% of the X-rays were reported as normal.
Other tests may include:
– Imaging tests: A CT scan can reveal small lesions in your lungs that might not be detected on an X-ray.
– Sputum cytology: sputum may reveal the presence of lung cancer cells.
– Tissue sample (biopsy): A sample of abnormal cells may be removed for histological analysis. A biopsy may be performed in a number of ways, including bronchoscopy, mediastinoscopy and needle biopsy. A biopsy sample may also be taken from adjacent lymph nodes.

The most probable diagnosis of this patient is Cotard syndrome.

Cotard syndrome is a rare mental disorder where the affected patient believes that they (or in some cases just a part of their body) is either dead or non-existent. This delusion is often difficult to treat and can result in significant problems due to patients stopping eating or drinking as they deem it not necessary. Cotard syndrome is often associated with severe depression and psychotic disorders.

Other options:
– Othello syndrome is a delusional belief that a patients partner is committing infidelity despite no evidence of this. It can often result in violence and controlling behaviour.
– De Clerambault syndrome (otherwise known as erotomania), is where a patient believes that a person of higher social or professional standing is in love with them. Often this presents with people who believe celebrities are in love with them.
– Ekbom syndrome is also known as delusional parasitosis and is the belief that they are infected with parasites or have ‘bugs’ under their skin. This can vary from the classic psychosis symptoms in narcotic use where the user can ‘see’ bugs crawling under their skin or can be a patient who believes that they are infested with snakes.
– Capgras delusion is the belief that friends or family members have been replaced by an identical-looking imposter.

Pneumothorax is defined as air in the pleural space and may be classified as spontaneous, traumatic or iatrogenic. Primary spontaneous pneumothorax occurs in patients without clinically apparent lung disease.
Primary pneumothorax has an incidence of 18-28 per 100,000 per year for men and 1.2-6 per 100,000 per year for women. Most patients present with ipsilateral pleuritic chest pain and acute shortness of breath. Shortness of breath is largely dependent on the size of the pneumothorax and whether there is underlying chronic lung disease.

Young patients may have chest pain only. Most episodes of pneumothorax occur at rest. Symptoms may resolve within 24 hours in patients with primary spontaneous pneumothorax. The diagnosis of a pneumothorax is confirmed by finding a visceral pleural line displaced from the chest wall, without distal lung markings, on a posterior-anterior chest radiograph.

Breathless patients should not be left without intervention regardless of the size of pneumothorax. If there is a rim of air >2cm on the chest X-ray, this should be aspirated.
Aspiration is successful in approximately 70 per cent of patients; the patient may be discharged subsequently. A further attempt at aspiration is recommended if the patient remains symptomatic and a volume of less than 2.5 litres has been aspirated on the first attempt.

If unsuccessful, an intercostal drain is inserted. This may be removed after 24 hours after full re-expansion or cessation of air leak without clamping and discharge may be considered.

The rationale behind the use of sodium bicarbonate is that it increases the alkalinity of the urine promoting lithium excretion. The preferred treatment in severe cases would be haemodialysis.

Lithium is a mood-stabilizing drug used most commonly prophylactically in bipolar disorder but also as an adjunct in refractory depression. It has a very narrow therapeutic range (0.4-1.0 mmol/L) and a long plasma half-life being excreted primarily by the kidneys. Lithium toxicity generally occurs following concentrations > 1.5 mmol/L.

Toxicity may be precipitated by dehydration, renal failure, diuretics (especially Bendroflumethiazide), ACE inhibitors, NSAIDs and metronidazole.

Features of toxicity
Coarse tremor (a fine tremor is seen in therapeutic levels)
Hyperreflexia
Acute confusion
Seizure
Coma

Management
Mild-moderate toxicity may respond to volume resuscitation with normal saline
Haemodialysis may be needed in severe toxicity
Sodium bicarbonate is sometimes used but there is limited evidence to support this. By increasing the alkalinity of the urine it promotes lithium excretion.

Gram-staining of the blood cultures of this patient will show gram-positive cocci. Gram-negative bacilli used to be the most common pathogen isolated in neutropenic sepsis, but currently, the most common pathogens are gram-positive organisms. Staphylococcus epidermidis is the most frequent causative agent, and following this are other staphylococci and streptococci species.

Neutropenic sepsis is a relatively common complication of cancer therapy—usually chemotherapy. It most commonly occurs 7-14 days after the treatment and is usually defined as a neutrophil count of <0.5 x 10^9/L in a patient undergoing anticancer treatment and who has either a temperature higher than 38°C or has other features consistent with clinically significant sepsis. Management approach includes starting empirical antibiotic therapy (piperacillin with tazobactam—Tazocin) immediately. Following this initial treatment, the patient is usually assessed by a specialist and risk-stratified to see if outpatient treatment may be possible. However, if the patient remains febrile and unwell after 48 hours, an alternative antibiotic such as meropenem is often prescribed with or without vancomycin. If patient is still not responding after 4-6 days, then an antifungal, such as amphotericin B, is started after carrying out investigations (e.g. HRCT and Aspergillus PCR) to determine the likelihood of systemic fungal infection.

The woman seems to have a chancroid, which may or may not drain to the lymph nodes of the groin. These nodes are the superficial inguinal lymph nodes.

Arthritis mutilans is a rare (occurs in only 5% of the patients) and extremely severe form psoriatic arthritis characterized by resorption of bones and the consequent collapse of soft tissue. When this affects the hands, it can cause a phenomenon sometimes referred to as ‘telescoping fingers.’ The associated nail changes are also characteristic of arthritis.

The dose is calculated, using the conversion factor, as follows:

(Conversion factor used to convert oral morphine to subcutaneous diamorphine = Divide the total daily dose of oral morphine by 3)
Hence,
60mg*2 = 120mg
120mg/3 = 40mg

The side effects of opioids can be transient or persistent, and these include constipation, nausea, and drowsiness. Therefore, all patients taking opioids should also be prescribed a laxative and an anti-emetic (if the nausea is persistent). Dose-adjustment may be necessary in cases of persistent drowsiness. Moreover, strong opioids can also provide quick relief from metastatic bone pain, as compared to NSAIDs, bisphosphonates, and radiotherapy.

The best answer is cytomegalovirus. The mother was infected during the pregnancy and the baby has developed cytomegalo-inclusion syndrome. Histologically, it is identified by viral particles surrounded by lysosomes.

In a patient with abnormal LFTs and UC, think primary sclerosing cholangitis (PSC). MRCP and liver biopsy is the best answer. MRCP will show classically beads on a string – intra and extrahepatic stricturing and dilation. Remember this finding!! Liver biopsy is required for official diagnosis (need tissue!).

Osteomalacia is a marked softening of the bones that can present in both type I and type II Renal Tubular Acidosis (RTA) and will thus not differentiate the two types in any case. The other measures will allow differentiation of the two types.

Squamous-cell skin cancer usually presents as a hard lump with a scaly top but can also form an ulcer. Onset is often over months and it is more likely to spread to distant areas than basal cell cancer vie the lymphatics. The greatest risk factor is high total exposure to ultraviolet radiation from the Sun. Other risks include prior scars, chronic wounds, actinic keratosis, lighter skin, Bowen’s disease, arsenic exposure, radiation therapy, poor immune system function, previous basal cell carcinoma, and HPV infection. While prognosis is usually good, if distant spread occurs five-year survival is ,34%

Cataract is a condition characterized by clouding of the lens of the eye. This condition most frequently occurs due to age-related degenerative processes in the lens, but can also be associated with ocular trauma, metabolic disorders, side-effects of drugs, or congenital infections. The clouding causes distortion of light, as it passes through the lens, resulting in visual impairment and glare. Initially, a cataract presents discretely and may even go unnoticed, but the visual impairment worsens as the cataract grows larger.

Diagnosis is typically established on the basis of a thorough history and direct visualization of the cataract (by means of slit-lamp microscopy). Surgery is indicated with significant visual impairment and involves lens extraction and implantation of an artificial lens. Untreated cataracts eventually lead to complete blindness.

This is a typical picture of acute chest syndrome (ACS). According to the British Committee for Standards in Haematology (BCSH), ACS is defined as ‘an acute illness characterised by fever and/or respiratory symptoms, accompanied by a new pulmonary infiltrate on chest X-ray’. ACS occurs in sequestration crisis, which is one of the four main types of crises occurring in sickle cell disease.

The fundamentals of initial management are as follows:
1. Oxygen therapy to maintain saturation >95%
2. Intravenous fluids to ensure euvolemia
3. Adequate pain relief
4. Incentive spirometry in all patients presenting with rib or chest pain
5. Antibiotics with cover for atypical organisms
6. Bronchodilators if asthma co-exists with acute chest syndrome, or if there is an evidence of acute bronchospasm on auscultation
7. Early consultation with the critical care team and haematology department

A senior haematologist then makes a decision as to whether a simple or exchange transfusion is necessary in order to achieve a target Hb of 10.0–11.0g/dL in either instance.

Sickle Cell Crises:
Sickle cell anaemia is characterised by periods of good health with intervening crises:
1. Sequestration crisis: acute chest syndrome (i.e. fever, dyspnoea, chest/rib pain, low pO2, and pulmonary infiltrates)

2. Thrombotic (painful or vaso-occlusive) crisis: precipitated by infection, dehydration, and deoxygenation

3. Aplastic crisis: sudden fall in haemoglobin without marked reticulocytosis, usually occurring secondary to parvovirus infection

4. Haemolytic crisis: fall in haemoglobin secondary to haemolysis, rare type of sickle cell crises

Attacks or exacerbations of multiple sclerosis (MS) are characterized by symptoms that reflect central nervous system (CNS) involvement, hence upper motor neuron symptoms are seen.

Results of a randomized trial confirm that the antidepressant sertraline can be used safely in patients with recent MI or unstable angina and is effective in relieving depression in these patients.

There are theoretical reasons for believing that selective serotonin reuptake inhibitors (SSRIs), widely used to treat depression, might increase the risk of gastrointestinal bleeding. Gastroprotective drugs are advocated for high risk patients taking non-steroidal anti-inflammatory drugs, another class of drug that causes gastrointestinal bleeding.

Serotonin is released from platelets in response to vascular injury and promotes vasoconstriction and a change in the shape of the platelets that leads to aggregation. Platelets cannot themselves synthesise serotonin. SSRIs inhibit the serotonin transporter, which is responsible for the uptake of serotonin into platelets. It could thus be predicted that SSRIs would deplete platelet serotonin, leading to a reduced ability to form clots and a subsequent increase in the risk of bleeding.

The well established association between nonsteroidal anti-inflammatory drugs and upper gastrointestinal bleeding is estimated to result in 700-2000 deaths/year in the UK. This has led to the recommendation that patients in high risk groups should receive gastroprotection in the form of an H2 antagonist, proton pump inhibitor (lansoprazole), or misoprostol.

Proton pump inhibitors have been shown to reduce endoscopically diagnosed mucosal damage and heal ulcers induced by non-steroidal anti-inflammatory drugs but not to reduce the incidence of severe gastrointestinal bleeds.

Human-papilloma virus (HPV) can lead to cervical cancer. There are many different types, but the types associated with cervical cancer most commonly are 16, 18, 31, 33, and 35. The vaccination against HPV protects against the most common types of HPV that are seen in cervical cancer and is recommended for children/young teens. Cervical cancer has a clear association with HPV, making this the best answer over all of the other answer choices.

Clozapine can cause neutropenia or agranulocytosis.

Clozapine is an atypical antipsychotic used in the treatment of schizophrenia, and in patients who are intolerant to, or unresponsive to other antipsychotics.

It is a weak D2-receptor and D1-receptor blocking activity, with noradrenolytic, anticholinergic, and antihistaminic properties.

Many antipsychotic drugs can occasionally cause bone marrow depression, but agranulocytosis is particularly associated with clozapine.

Other side effects include:
Hypotension, tachycardia
Fever, sedation, seizures (with high doses)
Appetite increase
Constipation
Heartburn
Weight gain
Extrapyramidal symptoms
Agranulocytosis
Neuroleptic malignant syndrome

In acute angle closure glaucoma (AACG) there is a rise in IOP secondary to an impairment of aqueous outflow. Management options include reducing aqueous secretions with acetazolamide and inducing pupillary constriction with topical pilocarpine.

The principal mechanism of action of taxanes (e.g. docetaxel) is the prevention of microtubule disassembly.

Other aforementioned options are ruled out because:

1. Doxorubicin: stabilizes DNA topoisomerase II complex and inhibits DNA and RNA synthesis.

2. Vincristine, vinblastine: inhibits formation of microtubules.

3. Cisplatin: causes cross-linking in DNA.

In statistical hypothesis testing there are 2 types of errors:
– type I: the null hypothesis is rejected when it is true – i.e. Showing a difference between two groups when it doesn’t exist, a false positive.
– type II: the null hypothesis is accepted when it is false – i.e. Failing to spot a difference when one really exists, a false negative.

The most sensitive test for detecting Hepatitis C infection (acute) is HCA RNA; it can be detected 1-2 weeks after infection. Anti-HCV antibodies take at least 6 weeks to develop and be positive.

Supraspinatus tendinopathy is a common and disabling condition that becomes more prevalent after middle age and is a common cause of pain in the shoulder. A predisposing factor is resistive overuse. This patient has the classic painful arc that is a sign of shoulder impingement characteristic of supraspinatus tendonitis.

Transposition of the great arteries results in a significant hypoxemic status that is observed clinically by central cyanosis. The bluish discoloration of the skin and mucous membranes is therefore the basic pattern of clinical presentation in transposition. Its onset and severity depend on anatomical and functional variants that influence the degree of mixing between the two circulations. Limited intercirculatory mixing, usually present if the ventricular septum is intact or the atrial septal defect is restrictive, is related to progressive and profound central cyanosis evident within the first hours of life. Tachypnoea, tachycardia, diaphoresis, poor weight gain, a gallop rhythm, and eventually hepatomegaly can be then detected later on during infancy. Heart murmurs associated with left outflow tract obstruction, due to a persistent arterial duct or a septal defect may be heard, but they are not a constant finding.

Acute dacryocystitis presents as inflammation of the lacrimal sac and is typically caused by infection. Symptoms of acute dacryocystitis can be pain, redness of the eye and swelling of the nasal aspect of the eye. The eye is usually watery and discharge can be expressed through the lacrimal punctum which is generally mucoid but can also be purulent. Patient can also present with fever.

Xeroderma pigmentosum is an X-linked recessive condition, which is caused by mutations in DNA gyrase which further encodes the XP gene. The defect may lead to skin cancer at an early stage of life, especially at photo exposed sites.

The patient likely has celiac’s disease, but if she has been avoiding gluten, a biopsy may be negative. Even though a biopsy is the gold standard for diagnosis, she will need to re-introduce gluten into her diet prior to undergoing the biopsy.