Paper 5 Answers
James Day, Amy Thomson, Tamsin McAllister, Nawal Bahal in Get Through, 2014
The kidneys clear 85% of furosemide; half of this is metabolized and the other half is actively secreted in an unchanged form in the proximal tubules. It is highly protein-bound (>98%) and only a small fraction is filtered through the glomerulus. The presence of another highly protein-bound drug, such as warfarin, reduces furosemide’s secretion and its diuretic effect. Its elimination half-life is 1.5–2 hours in healthy individuals but this is prolonged in renal failure. The site of action is at the sodium-chloride-potassium co-transporters at the intraluminal side of the ascending limb of the loop of Henle. 6A: True6B: False6C: False6D: True6E: TrueVasopressin is also known as antidiuretic hormone (ADH). It is responsible for regulating plasma osmolality and volume. It acts as a neurotransmitter in the brain controlling circadian rhythm, thermoregulation and adrenocorticotrophic hormone (ACTH) release. It is a nonapeptide and is synthesized in the paraventricular and supraoptic nuclei of the posterior hypothalamus. Vasopressin is metabolized by vasopressinases in the liver and kidney and has a half-life of 10–35 minutes. Desmopressin is a synthetic analogue of arginine vasopressin; it has 10 times the antidiuretic action of vasopressin but 1500 times less vasoconstrictor action. 7A: True7B: True7C: False7D: True7E: False
Ascorbate as an Enzyme Cofactor
Qi Chen, Margreet C.M. Vissers in Vitamin C, 2020
Norepinephrine and vasopressin are able to regulate blood flow, heart rate, and energy metabolism. Vasopressin is released from the pituitary in response to increased osmolality or decreased blood pressure and acts on the kidney and smooth muscle cells to regulate the reabsorption of water and constrict arterioles [264]. Effects of ascorbate availability on vasopressin were first demonstrated in animals in which ascorbate increased plasma vasopressin in association with changes in urinary volume and sodium excretion [263,265,266]. Vasopressor requirements are a major consideration in the clinical care of the critically ill, with management of hypotension presenting a major challenge for the doctors of patients with acute sepsis [267,268]. In response to strong evidence for severely depleted plasma vitamin C levels in these patients [269–274], a number of studies have been undertaken to determine the effect of ascorbate supplementation on vasopressor use and patient outcome in patients in intensive care. Early indications suggest that the recommended ascorbate levels in parenteral nutrition are inadequate and do not compensate for the accelerated turnover in these patients [272]. Substantial clinical benefit of additional vitamin C supplementation, manifest as decreased dependency on vasopressors [275], less multiple organ failure and a dramatic reduction in mortality [276] are suggested. These data have initiated significant interest and discussion, and more targeted clinical trials are anticipated [267,275,277–281].
The endocrine system
C. Simon Herrington in Muir's Textbook of Pathology, 2020
The posterior lobe of the pituitary can be viewed as a downward extension of the hypothalamus. Consequently it contains axonal projections originating in the hypothalamus and terminating on blood vessels where the hormones oxytocin and vasopressin are secreted directly into the blood. These hormones are synthesized in the hypothalamus and pass down nerve fibres in the pituitary stalk to be secreted into the peripheral circulation. The function of oxytocin is to stimulate uterine contraction in labour and ejection of milk in lactation. There are no known diseases associated with excess or deficiency. The function of vasopressin is to regulate fluid balance by stimulating water reabsorption in the kidney. Lack of vasopressin, due to conditions damaging the hypothalamus or pituitary gland, can cause a condition called diabetes insipidus where patients fail to reabsorb fluid in the kidneys and therefore suffer from extreme thirst (polydipsia) and production of large amount of dilute urine (polyuria). Inappropriate secretion of vasopressin, classically ectopic secretion from a small cell lung cancer can cause the syndrome of inappropriate antidiuretic hormone secretion (SIADH). This results in retention of fluid, hypo-osmolality and hyponatraemia. Tumours of the posterior pituitary gland are rare, but include traditional pituicytomas, oncocytic pituicytoma, and granular pituicytoma.
Lixivaptan: a novel vasopressin receptor antagonist
Published in Expert Opinion on Investigational Drugs, 2009
Elaine Ku, Niloofar Nobakht, Vito M Campese
Arginine vasopressin, also known as antidiuretic hormone, is a neuropeptide that functions in the maintenance of body water homeostasis. Inappropriate secretion of vasopressin has been implicated in the pathophysiology of multiple diseases, including polycystic kidney disease, syndrome of inappropriate antidiuretic hormone (SIADH) secretion, and the hyponatremia commonly associated with cirrhosis and congestive heart failure. Vasopressin receptor antagonists are novel agents that block the physiologic actions of vasopressin. Lixivaptan is a vasopressin receptor antagonist with high V2 receptor affinity and is now undergoing Phase III clinical trials. Studies so far have demonstrated that lixivaptan is efficacious in the correction of hyponatremia in SIADH, heart failure and liver cirrhosis with ascites, and few adverse effects have been noted. Thus, lixivaptan remains a promising therapeutic modality for the treatment of multiple diseases and prevention of the associated morbidity and mortality associated with hyponatremia.
Central Diabetes Insipidus in an Infant with Pneumococcal Meningitis
Published in Fetal and Pediatric Pathology, 2019
Seda Aydogan, Dilek Dilli, Ahmet Ozyazıcı, Emin Cakmakci, Ece Koyuncu, Ayşegül Zenciroğlu
Background: Central diabetes is an infrequent complication reported in the neonatal period. Case report: CDI as a complication of Streptococcus pneumoniae (S. pneumoniae) sepsis and meningitis in a 9-day-old boy is presented. The CDI developed on day 3 after admission and was controlled with nasal vasopressin on the 20th day of admission. Despite antibiotic support, the child died from Acinetobacter sepsis at 4 months of age, but the CDI was well controlled. Conclusion: Newborns with bacterial meningitis can develop CDI as a sequalae. Treatment of the CDI with nasal vasopressin can be successful in this period. To our knowledge, this is the first newborn of CDI associated with S. pneumoniae meningitis.
Serum oxytocin and vasopressin levels in children with social anxiety disorder and the effects of parent characteristics
Published in Psychiatry and Clinical Psychopharmacology, 2018
Miray Çetinkaya, Özden Şükran Üneri, Zeynep Göker
OBJECTIVES: We aim to determine serum oxytocin, vasopressin levels and examine parent characteristics in children diagnosed with social anxiety disorder (SAD). METHODS: Thirty four children diagnosed with SAD and 34 mothers were compared with a healthy control group (21 control children and their mothers) in this case–control study. Assessment performed via State-Trait Anxiety Inventory (STAI), Symptom Checklist-90 (SCL-90), Parental Attitude Research Instrument (PARI), Beck Depression Inventory (BDI), Liebowitz Social Anxiety Scale (LSAS) and Social Anxiety Scale for Children-Revised (SASC-R). Serum samples collected for detection of oxytocin and vasopressin levels. RESULTS: The distribution range of vasopressin levels were found statistically higher in control group than SAD group (p = 0,002). Additionally results showed no statistically significant differences according to the mean levels of serum oxytocin and vasopressin between groups. The scores of STAI-C, SASC-R and democratic attitudes/egalitarianism subscales of PARI were found significantly higher in children with SAD. Similarly we reported that mean scores of SCL-90 scale, LSAS and SCL-90 subscales were higher in mothers of patients group. CONCLUSIONS: Although significantly lower distribution range of vasopressin levels was found in SAD patients, mean oxytocin and vasopressin levels were not associated with SAD etiology. Additionally psychopathologies particularly anxious behaviour in mothers may contribute SAD development in early period of childhood.
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