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There are three major features of these sys- Three groups of nuclei in the brainstem (locus tems: (1) each has a relatively small number of ceruleus purchase 20mg levitra professional with visa erectile dysfunction treatment in lucknow, raphe buy discount levitra professional on line erectile dysfunction shake drink, and ventral tegmental) and one neurons buy levitra professional 20mg mastercard erectile dysfunction in 40s, that is, 10,000 to 15,000; (2) the axon in the basal forebrain (basal nucleus of Meynert) of each neuron travels a great distance, has innu- form the major part of the diffuse modulating merable branches, and may infuence more than system. Chapter 20 Reticular Formation: Modulation and Activation 263 Noradrenergic Locus Ceruleus are involved in the sleep-wake cycle and are also implicated in control of mood and certain types The locus ceruleus is a dark-colored nucleus with of emotional behavior, especially aggression. Its axons are distributed Dopaminergic Ventral to the cerebral cortex, thalamus, hypothalamus, Tegmental Area cerebellar cortex, brainstem, and spinal cord The ventral tegmental area is located posterome- (Fig. Its dopaminergic neu- locus ceruleus are involved in the regulation of rons project chiefy to the accumbens, amygdala, attention, cortical arousal, and the sleep-wake and prefrontal cortex (Fig. The relation- cycle, as well as learning, memory, anxiety, and ship of increased dopaminergic activity in the mood. Norepinephrine increases brain respon- accumbens nucleus elicited by psychostimulant siveness and speeds information processing. Neurons clustered in the midline of the medulla, pons, and midbrain form the serotonergic raphe Cholinergic Brainstem and Basal nuclei (Fig. Those near the pontomed- Forebrain System ullary junction are the nucleus raphe magnus, which projects to the spinal cord for the modu- Cholinergic neurons in the pons and midbrain lation of slow pain (see Chapter 11). Those in project to the thalamus and regulate the excit- the rostral pons and midbrain project to the ability of thalamic nuclei. Cholinergic neurons thalamus; to limbic system structures such as in the basal nucleus of Meynert (Fig. The widespread areas of the cerebral cortex and play serotonergic projections from the raphe nuclei a major role in cortical excitability, memory, Figure 20-3 Principal connections of noradrenergic axons of locus ceruleus. Figure 20-5 Principal connections of dopaminergic axons of ventral tegmental area. Chapter 20 Reticular Formation: Modulation and Activation 265 Figure 20-6 Principal connections of cholinergic axons of brainstem and basal nuclei. The degeneration of those neu- the rostral pons inhibits the inspiratory phase of rons in Alzheimer patients may account for their respiration and plays a major role in coordinating impaired cognitive functioning. It does so via pro- of the autonomic nervous system, respiration is jections descending through the periaqueductal actually a viscerosomatic refex that may be infu- gray and adjacent tegmentum of the midbrain. Those at the C3 and C4 levels innervate the dysfunction of structures deep in the cerebral diaphragm via the phrenic nerve, and those at the hemispheres or in the diencephalon results in T1 to T10 levels innervate the intercostal muscles Cheyne-Stokes respiration, in which hyper- via the intercostal nerves. The rhythmic activa- pnea alternates with apnea (no breathing), tion of these lower motor neurons is controlled by although this phenomenon may result in nor- inspiratory neurons located bilaterally in the ven- mal individuals under certain circumstances trolateral medulla in the vicinity of the nucleus and in patients with congestive heart failure. Injury of the dorsolateral near the solitary nucleus, which then projects to the tegmentum at rostral pontine levels results in ventrolateral respiratory center. The pneumotaxic apneustic breathing, which consists of prolonged center located in the dorsolateral tegmentum of inspiration alternating with prolonged expiration. Figure 20-7 Respiratory patterns associated with levels of lesions in comatose patients. Respiratory centers in mid-medulla—respiratory arrest Chapter 20 Reticular Formation: Modulation and Activation 267 Cluster breathing in which there are three or fuctuations of heart rate, blood pressure, res- four rapid, deep breaths alternating with periods piration, and body temperature; miosis; penile of apnea may occur with damage at midpontine erection and clitoral engorgement; dreaming, levels. This area enon that is regulated chiefy by centers in the is extremely complex and appears to include indi- pontine reticular formation. Sleep apnea is the absence of breathing for a The role of other groups of neurons in the considerable period of time, that is, a minute brainstem and forebrain in controlling sleep is or more, during sleep. For instance, noradrenergic way obstructions or defcient central respira- neurons in the locus ceruleus and serotonergic tory mechanisms. It occurs repetitively, and the neurons in the raphe nuclei are active during victim awakens each time, so that it results in wakefulness. Cholinergic neurons in the basal sleepiness when awake as a result of the loss forebrain and dorsolateral pontine reticular for- of sleep. Dopaminergic neurons in the hypothalamus and brainstem are active in sleep and wakefulness. What are the chief cranial nerve, spinal auditory, visual and, in fact, any or all of the sen- cord, and forebrain inputs to the reticular sory pathways cannot awaken the cerebral cor- formation? Alterations in which basal forebrain neurons in the dorsolateral pontine tegmen- nucleus are associated with decreased tum. The pleasure induced by psychostimulants nuclei and to intralaminar and other nuclei that such as amphetamine or cocaine is have widespread cortical connections.
Onset and progression of puberty is associated with development and wors- ening of diabetic retinopathy generic levitra professional 20 mg on-line erectile dysfunction is often associated with. Intensive insulin therapy is associated with initial worsening of diabetic reti- nopathy followed by slow progression of the disease discount levitra professional 20mg line erectile dysfunction doctors in st louis mo. Therefore cheap 20 mg levitra professional fast delivery erectile dysfunction drugs research, periodic fundus examination should be performed after initiation of intensive insulin therapy. Limited joint mobility correlates with diabetic microvascular complications particularly diabetic retinopathy (Fig. The presence of ketoacidosis in a diabetic patient with blood glucose <250 mg/dl is termed as euglycemic diabetic ketoacidosis. Hourly monitoring of blood glucose is recommended for initial 24h to titrate the rate of insulin infusion. When blood glucose level is reduced to <200 mg/dl, 5% dextrose infusion should be added to prevent hypoglycemia, and the dose of insulin infu- sion is to be reduced. Arterial pH and serum anion gap should be monitored every four to six hours, and with effective treatment, arterial pH increases and serum anion gap progressively decreases. The presence of hypokalemia at presenta- tion suggests severe depletion of body stores of potassium, and hypokalemia may worsen after insulin infusion therapy. Failure to respond to therapy suggests inadequate fuid replacement, suboptimal insulin therapy, occult infection, or other causes of metabolic acidosis (lactic acidosis or uremia). Ketone bodies (acetone, acetoacetate, and β-hydroxybutyrate), being lipophilic, accumulate in adipose tissue. In the index case, calculated serum osmolality was 295 mOsm/Kg; there was no electrolyte abnormality and acidosis was mild. Therefore, alternative causes for altered sensorium should be actively sought in the index patient including men- ingitis, cortical vein thrombosis, stroke, and rhinocerebral mucormycosis. The index patient was evaluated and was found to have concur- rent pyogenic meningitis. This is because of relatively lower portal concentration of insulin is required to suppress hepatic glucose output (fasting hyperglycemia) as com- pared to inhibition of ketosis. Patients with diabetes are predisposed for certain infections which include emphysematous pyelonephritis, emphysematous cholecystitis, malignant otitis externa, rhino–orbito–cerebral mucormycosis, and liver abscess. The increased risk for these infections in patient with diabetes is due to glucotoxicity-mediated lazy leukocyte syndrome and impaired humoral and cellular immunity (Fig. Increased prevalence of childhood obesity as a result of sedentary lifestyle and consumption of calorie-dense food predisposes for the early development of diabetes. Biochemistry revealed fasting plasma glucose of 190 mg/dl, postpran- dial glucose 220 mg/dl, and HbA1c 8. He 12 Diabetes in the Young 415 should be carefully examined for other features of insulin resistance (double chin, skin tags, and central obesity), hypertension, and xanthelasmas. The index patient was advised to follow lifestyle modifcation and was initiated on metformin 1 g twice a day after meals. The monogenic forms of diabetes are rare and contribute only 1–2 % of individuals with diabetes. During adolescence and early adulthood, these individuals have normal fasting plasma glucose, but have hyperglycemia during oral glucose tolerance test. The important differentiating features between the two disorders are summarized in the table given below. Therefore, glucokinase is a key enzyme which regulates the rate of entry of glucose into the glycolytic pathway and its subsequent metabolism in β-cell. The most affected individuals are asymptomatic and are detected during screening (e. How do hepatocyte nuclear transcription factors regulate insulin secretion and glucose metabolism? Hepatocyte nuclear transcription factors are expressed not only in the liver but also in the pancreatic β-cells and urogenital tissues. These proteins regu- late tissue-specifc gene expression and thereby determine growth and development, as well as facilitate metabolic signaling in these organs. During embryogenesis, these transcription factors act in concert to promote islet devel- opment and regulate the expression of insulin gene, and genes-encoding pro- teins which are linked to insulin secretion. Diabetes is prevalent in approximately 60 % of individuals and occurs at an early age. These individuals are often diagnosed to have type 2 diabetes and started on oral antidiabetic drugs; however, most of these individual will require insulin within a few years.
Fat emboli may occur secondary to trauma and also in association with collagen vascular disease purchase levitra professional cheap impotence what does it mean. Tumor emboli may carry metastatic disease from the kidneys or other abdominal organs generic 20mg levitra professional free shipping erectile dysfunction news, or they may be present in association with infiltrative carcinomatous disease of the lung order 20mg levitra professional with amex erectile dysfunction treatment psychological causes, and thromboembolic pulmonary hypertension is also associated with tumor chemotherapy. In the newborn and young infant, pulmonary thrombosis may be associated with sepsis and dehydration and portal or renal vein thrombosis, and it is seen with nephrotic syndrome. The nature of the pulmonary vascular abnormalities in thromboembolic disorders has not been studied extensively in children, but findings can be expected to be similar to those described in adults. In postmortem pulmonary arteriograms of adult patients, some vessels show evidence of thrombi (seen as filling defects), and filling of the peripheral distribution of these vessels with contrast material is scant. Upon microscopic examination of the abnormally filled areas, fibrous intimal hyperplasia is observed, mostly eccentric in nature, in both the preacinar and peripheral intra-acinar arteries. Some vessels show evidence of having been completely occluded and later recanalized. Microscopic examination of areas that appear normal on the arteriogram show intra-acinar pulmonary arteries that are increased both in size and concentration, suggesting compensatory dilation and recruitment. Throughout the lung, there may be medial hypertrophy of muscular arteries, but this probably depends on the duration of the disease and the severity of pulmonary hypertension. Venous angiogram (B) shows site of tumor (infiltrative reticulum cell sarcoma) in inferior vena cava. Right ventricular cineangiogram (C) demonstrates large embolus from same tumor in right pulmonary artery. Cells isolated from tissue obtained during pulmonary endarterectomy showed characteristics of both endothelial cells and myofibroblast-like cells, and were found to be hyperproliferative, anchorage-independent, invasive, similar to the pathology seen in other forms of pulmonary hypertension (105,106,107). There have been advances in treatment by surgical thromboendarterectomy, which remains the treatment of choice (109). Sickle Cell Disease and Other Hemaglobinopathies There has been increasing recent attention given to the complication of pulmonary hypertension in patients with sickle cell disease (111) and other hemaglobinopathies such as thalassemia. There may be additional contribution from elevated left atrial pressure from cardiomyopathy and resulting left ventricular diastolic dysfunction. Initial results of studies using sildenafil to treat chronic pulmonary hypertension suggest hemodynamic benefits (113) but a recent double-blind, placebo- controlled trial was terminated early due to concern for increased pain crises in the patients treated with sildenafil (114). Portal Hypertension Severe liver disease producing cirrhosis and intrahepatic portal hypertension, as well as portal vein thrombosis producing extrahepatic portal hypertension have been associated with the development of pulmonary hypertension (117). Severe structural changes, consisting of medial hypertrophy, occlusive cellular intimal hyperplasia, plexiform lesions, and dilation complexes, occur in the peripheral pulmonary arteries. It has therefore been postulated that the “toxic liver” is unable to degrade a certain substance that then circulates through the lung in high concentration, causing structural damage to the vessels. In some patients with liver disease, however, there is generalized vasodilation of the vessels in the lung (118). In other patients, anastomoses develop between pulmonary and hepatic arteries (119). Thus, the pulmonary vascular response (both structural and hemodynamic) in individual patients with liver disease may differ greatly. Severe pulmonary hypertension should not be considered a contraindication to liver transplantation because regression of the hemodynamic abnormality has been described. Recently portopulmonary hypertension has been linked to a polymorphism in S100A4, (120) a gene we related to experimental pulmonary hypertension, discussed later in this chapter. While unusual in the pediatric population, pulmonary hypertension may occur either in adults or children with sarcoidosis. This seems to be due to the presence of obstructive granulomas within the pulmonary arteries, although obliteration of the vasculature by parenchymal fibrosis and hypoxic vasoconstriction may also contribute. In addition to high circulating levels of endothelin-1 (indicative of an endothelial injury) there is increased production of autoantibodies that reflect the immune compromise. Pulmonary hypertension has been associated with significant morbidity and mortality in pediatric patients with juvenile idiopathic arthritis, which likely results from severe uncontrolled disease and may be influenced by exposure to biologic therapies (124). There is also altered adaptive immunity, initially characterized in patients with systemic sclerosis with autoantibodies targeting the vasculature. In scleroderma a trial has been initiated to deplete B cells based upon studies showing that these cells may be driving the immune– inflammatory response. This receptor normally protects the pulmonary vasculature, as will be discussed later in the chapter.
In some instances order levitra professional 20 mg online erectile dysfunction under 40, it may be possible to use the It may also be appropriate to perform a plasty with a running homograft annulus to primarily close the infundibular inci- suture line across the posterior wall of the branch pulmonary sion buy generic levitra professional online erectile dysfunction treatment by food. In all likelihood discount generic levitra professional uk erectile dysfunction ed drugs, however, use of a small pericardial arteries internally without resection. Care should be taken patch will be necessary to close the infundibular incision to avoid excessively narrowing the central pulmonary arter- with the cephalad end of the pericardial patch sutured to ies if the child’s symptoms are mild. Prior to com- plasty of the pulmonary arteries nor insertion of an ortho- pletion of the homograft anastomosis, the heart is allowed to topic pulmonary valve is indicated. The aortic cross-clamp is released with the cardioplegia site When Should an Orthotopic Pulmonary Valve Be Placed? Because absent pulmonary valve syndrome is a rare anom- aly, it is diffcult to answer this question with certainty. It is usually not necessary to place a pulmonary artery as insertion of a pulmonary valve. Two atrial that is, bringing the dilated right pulmonary artery anterior pacing wires and a single ventricular pacing wire should be to the aorta. The segmental branches appear as multiple small branches arising directly from the pulmonary artery aneurysms. The anastomosis to the right ventricle is supplemented with a hood of autologous pericardium. Litwin and colleagues87 described an innovative pro- Because absent pulmonary valve syndrome is a particularly cedure in which the left pulmonary artery was removed from rare anomaly and in addition it exists in a wide spectrum of the mediastinum and replaced anterior to the ascending aorta severity, it is diffcult to know what the risks are for the surgi- using a tubular prosthetic interposition graft. The fact that numerous associates88 reported successful use of a valved homograft surgical approaches were described in the frst decades of car- in two teenage patients in 1972. J Am Coll Cardiol consecutive patients with absent pulmonary valve syndrome 2002;39:1664–9. Frequent asso- ative survival rates at 1, 5, and 10 years were 83, 80, and 78%, ciation of 22q11. Cardiac neural crest variate analysis were the presence of respiratory distress (p orchestrates remodeling and functional maturation of mouse = 0. The patients were followed for 72 ± 50 development of the pulmonary infundibulum and its sequelae. Report of the New England Regional Infant Cardiac successful repair without a conduit. Anomalous left System- und Lungenarterie mit Hilfe von Kunststoffprothesen coronary artery from the right pulmonary artery with aortic bei Cyanotischen Herzvitien. Proc Staff Meet Mayo repairs of ventricular septal defect, atrioventricular commu- Clin 1955;30:201–6. J Thorac Cardiovasc Surg infancy using profound hypothermia with circulatory arrest 1979;77:826–31. J Thorac Cardiovasc Surg repair minimizing the use of conduits in neonates and 1994;107:1291–300. Ann Surg artery: report of two cases presenting as obstructive lung dis- 2000;232:508–14. The syndrome resonance in evaluating pathophysiology and for pulmonary of absent pulmonary valve. The syndrome of absent pulmonary valve and ventricular septal defects anatomical features and embryological indications. The embryology of the conotruncal malforma- untreated patients with transposition and intact ventricular tions is described in greater detail in Chapter 28, Double- septum, death occurs early in infancy, generally follow- Outlet Right Ventricle. Not surprisingly, therefore, there were many of Van Praagh4 suggests that the primary problem is underde- attempts in the early years of open heart surgery in the 1950s velopment of the subpulmonary conus. This results in fbrous to undertake surgical correction for these unfortunate blue continuity between the pulmonary and mitral valves, a hall- babies. The common, dextro form of transpo- cal correction in the form of the arterial switch procedure sition is described using Van Praagh’s segmental approach as became the standard of care. Balloon atrial septostomy, introduced by Rashkind in their usual relationship with the morphological left ventricle Philadelphia,1 was one of the frst widely applied interven- on the left and the morphological right ventricle anterior on tional catheter techniques. In contrast, that corrective neonatal surgery could be performed with levo or l-loop transposition (congenitally corrected transpo- remarkably low mortality. Finally, children with simple sition) has an entirely different pathophysiology relative to transposition who have few associated extracardiac anoma- d-loop transposition (see Chapter 33, Congenitally Corrected lies have demonstrated that it is possible to take a child with a Transposition of the Great Arteries).
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