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These results were interpreted as indicating that the predom inant cause of resistance to AN P in dogs with low-output congestive heart failure is a reduction in RPP buy cheap clomid 100 mg line. Fluid intake 20 20 A prim ary decrease in cardiac output (indi- Net volume intake cated by dark blue arrow) leads to a Nonrenal 10 10 decrease in arterial pressure clomid 25mg without a prescription, which decreas- fluid loss – + es pressure natriuresis and volum e excre- 0 0 tion. These decreases expand the ECF vol- 0 10 20 30 um e. The inset graph shows that the ratio ECF volume, L of interstitial volum e (solid line) to plasm a + – Rate of change + volum e (dotted line) increases as the ECF Arterial Kidney volume Extracellular of extracellular pressure output fluid volume volum e expands because the interstitial fluid volume com pliance increases. Thus, although + expansion of the ECF volum e increases Total peripheral blood volum e and venous return, thereby + resistance Blood volume + restoring cardiac output toward norm al, + Autoregulation this occurs at the expense of a dispropor- + + M ean circulatory tionate expansion of interstitial volum e, Cardiac output Venous return filling pressure often m anifested as edem a. H epatic venous outflow obstruction leads to portal hypertension. Hepatic venous SVR – Hepatic venous According to the underfill theory, transudation from the liver leads outflow obstruction outflow obstruction to reduction of the blood volum e, thereby stim ulating sodium (N a) retention by the kidney. As indicated by the question m ark near the + term blood volum e, a low blood volum e is rarely detected in clini- cal or experim ental cirrhosis. Furtherm ore, this theory predicts that ascites would develop before renal N a retention, when the reverse Transudation Transudation generally occurs. According to the overflow theory, increased por- tal pressure stim ulates renal N a retention through incom pletely + defined m echanism s. The vasodilation theory suggests that Renin portal hypertension leads to vasodilation and relative arterial ↓ Blood volume ↑ ECF volume hypotension. Evidence for vasodilation in cirrhosis that precedes? UNaV FIGURE 2-31 Vasodilators Vasoconstrictors Alterations in cardiovascular hem odynam ics in hepatic cirrhosis. H epatic dysfunction and Nitric oxide portal hypertension increase the production and im pair the m etabolism of several vasoac- Glucagon CGRP tive substances. The overall balance of vasoconstriction and vasodilation shifts in favor of ANP SNS dilation. Vasodilation m ay also shift blood away from the central circulation toward the VIP RAAS periphery and away from the kidneys. Som e of the vasoactive substances postulated to Substance P Vasopressin ET-1 participate in the hem odynam ic disturbances of cirrhosis include those shown here. Prostaglandin E2 AN P— atrial natrivretic peptide; ET-1— endothelin-1; CGRP— calcitonin gene related Encephalins TNF peptide; RAAS— renin/angiotensin/aldosterone system ; TN F— tum or necrosis factor; Andrenomedullin VIP— vasoactive intestinal peptide. Com pared with control subjects (A), patients with cirrhosis (B) have decreased central and increased non- 1. The higher cardiac output (CO ) results from peripheral vasodila- 1. Perfusion of the kidney is reduced significantly in patients with cirrhosis. Com pared with control rats, rats having cir- Cirrhosis & L-name rhosis induced by carbon tetrachloride and phenobarbital exhibited increased plasm a renin activity (PRA) and plasm a arginine vaso- 10 10 pressin (AVP) concentrations. At steady state, the urinary N a excre- tion (UN aV) was sim ilar in both groups. After treatm ent with L- N AM E for 7 days, plasm a renin activity decreased to norm al lev- els, AVP concentrations decreased toward norm al levels, and urinary N a excretion increased by threefold. These changes were 5 5 associated with a norm alization of m ean arterial pressure and car- diac output. A prim ary decrease in system ic + 20 Fluid intake 20 vascular resistance (indicated by dark blue Net volume arrow), induced by m ediators shown in intake 10 10 Figure 2-31, leads to a decrease in arterial Nonrenal fluid loss – pressure. The reduction in system ic vascular + 0 0 resistance, however, is not uniform and 0 10 20 30 favors m ovem ent of blood from the central ECF volume, L (“effective”) circulation into the peripheral + – Rate of change + circulation, as shown in Figure 2-32. Arterial Kidney volume Extracellular of extracellular H ypoalbum inem ia shifts the interstitial to pressure output fluid volume fluid volume blood volum e ratio upward (com pare the + interstitial volum e with norm al [dashed Total peripheral line], and low [solid line], protein levels in Central Peripheral + resistance blood volume blood volume the inset graph). Because cardiac output increases and venous return m ust equal car- + + diac output, dram atic expansion of the + M ean circulatory extracellular fluid (ECF) volum e occurs. Cardiac output Venous return filling pressure M echanisms of Extracellular Fluid Volume Expansion in Nephrotic Syndrome FIGURE 2-35 14 Changes in plasm a protein concentration affect the net oncotic pressure difference across 12 capillaries ( c - i) in hum ans. N ote that m oderate reductions in plasm a protein concen- tration have little effect on differences in transcapillary oncotic pressure. O nly when plas- 10 m a protein concentration decreases below 5 g/dL do changes becom e significant. N ote that urinary N a excretion (squares) increases Plasm a renin activity (PRA) and atrial natriuretic peptide (AN P) before serum album in concentration increases. The data suggest concentration in the nephrotic syndrom e. Shown are PRA and that the natriuresis reflects a change in intrinsic renal N a retention. AN P concentration ( standard error) in norm al persons ingesting The data also em phasize that factors other than hypoalbum inem ia diets high (300 m Eq/d) and low (20 m Eq/d) in sodium (N a) and in m ust contribute to the N a retention that occurs in nephrosis. PRA suppression suggests that prim ary renal N aCl retention plays an im portant role in the pathogenesis of volum e expansion in AGN. Although plasm a renin activity in patients with nephrotic syndrom e is not suppressed to the sam e degree, the absence of PRA elevation in these patients suggests that prim ary renal N a retention plays a significant role in the pathogen- esis of N a retention in N S as well. The glom erular filtration rates (GFR) in norm al and nephrotic rats are shown by the hatched bars. N ote the m odest reduction in GFR in the nephrotic group, a finding that is com m on 60 60 in hum an nephrosis. Fractional reabsorption rates along the proxi- m al tubule, the loop of H enle, and the superficial distal tubule are indicated. The fractional reabsorption along the collecting duct 40 40 (CD) is estim ated from the difference between the end distal and urine deliveries. The data suggest that the predom inant site of 20 20 increased reabsorption is the collecting duct. Because superficial and deep nephrons m ay differ in reabsorptive rates, these data would also be consistent with enhanced reabsorption by deep 0 0 nephrons. Asterisk— data inferred from the difference between dis- GFR Proximal Loop Distal CD (*) tal and urine sam ples. As + 0 0 discussed in Figure 2-35, these effects of 0 10 20 30 hypoalbuminemia are evident when serum ECF volume, L albumin concentrations decrease by more + – Rate of change + than half.
Plasma concentrations of testosterone and self-reported 'irritability' (a correlate of aggression) in a small sample of male personality-disordered and healthy appear to be higher in persons with alcoholism with a his- volunteer subjects (30) safe clomid 50mg. Arole of -NE receptors in aggres- tory of repeated episodes of domestic violence than in com- 2 sion has been suggested by animal data in which the intrahy- parison groups (95) order 50mg clomid. In criminal offenders, higher CSF tes- pothalamic injection of -NE agents enhances aggressive tosterone concentrations were found in antisocial impulsive 2 responding in the cat (86). The authors suggested that one violent offenders, but they were not found in nonantisocial putative mechanism underlying this finding could involve impulsive or nonimpulsive violent offenders, in comparison stimulation of -heteroceptors on presynaptic 5-HT neu- with a healthy volunteer control group. There are some reports from in prospective, blinded Support for a DAhypothesis of human aggression is studies suggesting that administration of exogenous testos- also limited. Although some studies reported no relationship terone may result in aggressive behaviors (96), but the per- between CSF HVAand aggression (12,15), other studies centage experiencing severe mental disturbances is likely to suggested the presence of an inverse relationship between be small (97–99). Anabolic steroid administration may not these variables. Areduction in CSF HVAin antisocial, be uncommon among prisoners (100), and it may induce though not 'explosive,' impulsive violent offenders was re- abnormal personality traits in body builders (101). Areduction in CSF HVAhas also istic studies of testosterone concentrations are limited in been reported among recidivist violent offenders in compar- their interpretation because of the pulsatile nature of testos- ison with nonrecidivist violent offender controls (16), a terone release, so particularly plasma concentrations may be finding suggesting that reduced dopaminergic function quite variable, whereas CSF may be more reflective of aver- plays a role in predicting future aggressive behavior. Studies of exogenous steroid administration are findings must be taken with caution, however, because an complicated by, in most cases, the uncontrolled nature of inverse relationship between CSF 5-HIAA and aggression this steroid use. Chapter 119: Pathophysiology and Treatment of Aggression 1713 Cortisol criminally violent subjects). It is possible that agents that dampen central vasopressinergic activity could have anti- In general, cortisol concentrations are reported to be rela- aggressive efficacy. This finding is consis- tent with the negative correlation between cortisol and tes- tosterone concentrations (102) in volunteer subjects under Opiates controlled conditions. Correlations have been found among Although opiate withdrawal may precipitate aggressive be- plasma PRL, testosterone, and aggression, but not with cor- havior, there has been little study of the relationship of tisol, although cortisol and PRL concentrations were corre- aggression with endogenous opiates. In one study, a CSF lated with each other in their day-to-day changes in one opioid-binding protein was positively correlated with 'as- study (103). In children, increases in cortisol during the saultiveness' in healthy male volunteers (110). Circulating day were correlated with increased aggression (104). Alow levels of metenkephalins have been associated with self-inju- concentration of salivary cortisol was associated with persis- rious behaviors in a limited number of studies (111). Post- tent aggression in boys referred because of disruptive behav- mortem brain studies of violent suicide victims have also ior (105). In criminal offender or antisocial populations, found greater numbers of -opioid receptors as well (112). Plasma cortisol has also been re- induced than the placebo conditions (113), whereas naltrex- ported to be reduced in persons with alcoholism and a his- one, an opiate blocker, attenuated self-injurious behavior tory of repeated domestic violence (95) but increased after (114). These studies suggested that increased opioid activity cessation of drinking in incarcerated persons with alcohol- may increase the likelihood of aggressive behavior. However, the data in both animals and man are inconsistent because a positive correlation has been observed between plasma ACTH and aggression in nonhuman pri- Cholesterol and Fatty Acids mates (19), and cortisol rises during competition for domi- Some studies, both from persons who attempted suicide nance in vervet monkey males (107). The relationship be- and from healthy persons, suggested that reduced serum tween cortisol and aggression is thus likely to be complex cholesterol may be associated with aggressive behavior (115, and dependent on social context and stress. Male monkeys randomized to a low-fat and low-cho- lesterol diet displayed more aggressive behavior and less pro- Neuropeptides social behaviors than those randomized to a high-cholesterol diet (117,118). In humans, pharmacologic reduction of Among peptides neurotransmitters and modulators, limited cholesterol may increase the risk of non–illness-related mor- data suggest a positive relationship between aggression and tality such as death by suicide or trauma related to aggression central vasopressin and central opioid activity. Naturally occurring reduced cholesterol may also be associated with non–illness-related mortality (116, 120–123), largely attributable to suicide (116,122). Low Vasopressin serum cholesterol has been reported in psychiatric inpatients Whereas Virkkunen et al. Reduced serum vasopressin concentrations among impulsive and nonim- cholesterol has also been related to the severity of borderline pulsive violent offenders (8), Coccaro et al. It is also found in male forensic patients (130), aggres- sons, particularly men (108). Despite a significant inverse sive conduct-disordered children and adolescents with at- correlation between CSF vasopressin and PRL[d-FEN] re- tention deficit disorder (131), and suicidal adolescents sponse, the positive relationship between aggression and (132). CSF vasopressin remained even after the influence of PRL[d-FEN] response on the aggression score was taken into account. These data are consistent with those from MOLECULAR GENETICS animal studies in which vasopressin antagonists reduced ag- gression in golden hamsters, whereas 5-HT uptake inhibi- An understanding of the molecular genetics of impulsive tors increased central 5-HT activity and reduced central aggression is currently emerging with the rise of association vasopressin concentration and levels of aggressive behavior studies involving various DNApolymorphisms of candidate in the same species (109). One of the first notable studies in this area was that human studies may be accounted for by significant differ- of Brunner et al. The presence of this mutation function also contributed to failures to inhibit responses to was associated with evidence of altered catecholamine me- stimuli associated with punishment on a 'go/no-go' learn- tabolism (i. Al- cerebral dysfunction has also been related to increased hos- though no other families with this specific MAO A point tility. Verbal signal decoding and P300 amplitudes in an mutation have been reported, this report highlighted the evoked potential paradigm predicted impulsiveness and potential of the candidate gene approach to the molecular anger in prison inmates (147). In terms of regional localiza- genetics of aggression. At about the same time, Nielson et tion, neuropsychological tasks sensitive to frontal and tem- al. Thus, neuropsychological and associated with a reduction of CSF 5-HIAA concentration cognitive studies do suggest that abnormalities of higher in impulsive violent offenders (nearly all with DSM-III integrative functions, consistent with reduced cortical in- IED) (134). In the same study, the presence of the L allele hibitory influences on aggression, result in more disinhibi- was also associated with history of suicide attempts in all tion of aggressive behaviors. Although this finding was not replicated laboratory paradigms may discriminate aggressive individu- by Abbar et al. The PSAP has been externally validated in violent offenders and more specifically for severe suicide attempts. However, sional measures of impulsive aggression (137). In this brief the heritability of these laboratory measures has not been report of only 21 personality-disordered subjects, those with systematically assessed in studies of families or sibs of impul- the LL genotype had significantly higher aggression scores sive or aggressive probands, a logical prerequisite to an endo- than subjects with the UU genotype.
Functional mapping of the human visual cortex bymagnetic resonance not possible to constrain the timing or performance of a imaging cheap 100 mg clomid with mastercard. Considerable world attention in the last century has focused tions affording the government greater control over federally on the ethics of clinical research with human subjects buy discount clomid 50mg on line. Institutions were required to develop Insti ing to the fore after World War II, with the Nuremberg tutional Review Boards (IRBs) to review research protocols War Crimes Trials, concerns were raised about the potential to protect human subjects and ensure an adequate consent for abuse of nonvoluntary, uninformed subjects who might process. Out of the trials came Beginning in the 1990s public concern again grew, as the Nuremberg Code (1), which formalized ethical princi- research with patients with mental illness became a focus ples surrounding research with human subjects. As an example, Hilts (6) in a 1953, the United States opened the doors to the Clinical widely publicized media report, described a study in which Center of the National Institutes of Health, guiding princi- the use of methylphenidate in research subjects 'threw 60 ples regarding human subject research at that institution per cent of them into severe psychotic episodes. By the following decade, in 1964, the at Los Angeles (UCLA) involving outpatients with psychotic World Medical Association developed the Declaration of disorders who were withdrawn from active antipsychotic Helsinki, which was an attempt to modify and expand upon medications and observed for signs of relapse over time. This document classified research One patient ultimately committed suicide more than a year into clinical and nontherapeutic categories, and outlined after leaving the study, whereas a second had a significant the practice of consent that these types of research would exacerbation in psychotic symptoms, resulting in threats to require. The Declaration has since gone through multiple kill his parents. In 1994 the federal Office of Protection revisions and continues to be a significant guideline for re- from Research Risks (OPRR) investigated allegations that search with human subjects, especially in Europe. Although the OPRR did not find ples and practices of human subject research, repeated unethical research practices, they questioned the adequacy abuses were widely publicized in the ensuing years: the of the informed consent process for this potentially high- Tuskegee syphilis study (3), studies involving injection of risk study (11). As each story was exposed, it issues raised in psychiatric research. One of the foci has inspired international review of the ethics of human subject been the process of informed consent in studies involving research. Minority populations and those who may be vul- subjects who may have impairments in their abilities to nerable to exploitive research, such as the mentally ill, make decisions, such as patients with severe mental illnesses. In the United States, federal A 1995 report of the Advisory Committee on Human Ra commissions and agencies were created to address the con- diation Experiments (ACHRE) found that approximately cerns. Among the outcomes of these initiatives were regula- half of the studies it examined had 'inadequate explanations of risks and discomforts in their consent material and paid no attention to the question of how to deal with subjects Debra A. Appelbaum: University of Massachusetts who might have impaired capacities to consent to research Medical School, Worcester, Massachusetts participation' (5). In December of 1998, NBAC issued its through the use of double-blind, randomized, placebo-con- report entitled Research Involving Persons with Mental Disor trolled studies. In fact, this type of study design has been ders That May Affect Decision-making Capacity (12). Among touted has 'one of the major achievements of modern medi other things, the report recommended that an independent cine' (20). The report generated a swift and critical re mental design has important scientific merit in establishing sponse from many psychiatric professionals who expressed therapeutic efficacy as long as the objectives and the ration- concern that the recommendations reflected the misconcep ale for placebo use are clear (1). However, the FDA cautions tion that all persons with mental illness have decision-mak that placebos should not be used 'where existing treatment ing impairments. Thus, some considered the recommenda is life-prolonging' or if the placebo 'exposes patients to a tions too restrictive and stigmatizing of persons with documented serious risk' (1). Charney (14), Some authors have argued that findings of placebo re- however, wrote on behalf of the psychiatric research com search are misleading and deceptive (21), and that more or munity that the NBAC report provided some valuable con equally reliable findings could be had using active control tributions to the ongoing debate, and acknowledged that agents (16,22). A central argument against the use of place 'there is a crisis in confidence in the ethics of psychiatric bos in research on serious mental illnesses is that they are research' that needed to be addressed. NBAC responded likely to contribute to a relapse of or failure to resolve psy to the criticisms by stating that they envisioned their report chiatric symptoms. One early report suggested that psy as 'part of a continuing societal conversation... In addition to the potential risks associated with decision-making capacity' (15). Specifi cal concern regarding research with human subjects with cally, prolonged periods of significant psychological distress neuropsychiatric disorders, including subject recruitment, may be associated with loss of interpersonal relationships, confidentiality, data access, and conflicting roles of investi financial losses, and increased risk of suicide. More recently, certain meth Despite the risks, by now it is relatively clear that the odologic practices, such as placebo-controlled studies, drug use of nonactive agents as a means of control has scientific withdrawal studies, and the so-called 'challenge' studies, merit when effective treatments for a particular illness are have attracted particular attention. When effective treatments do exist, a pla about methodology, the ability of patients with mental ill cebo comparison may still allow investigators to establish nesses to provide informed consent to research procedures efficacy, learn more about the natural course of the illness, has probably been one of the most controversial issues sur and compare side effect profiles of active agents against non- rounding psychiatric clinical research, as highlighted in the active compounds. Moreover, historic controls are Placebo Studies not an adequate substitute for placebos because the apparent In the mid-1990s, controversy over the use of placebos in increase in the prevalence of experimental subjects who may research was rekindled; some commentators (16,17) con- already be resistant to treatment with standard medications tended that placebo use is unethical when standard effective (25,26). Thus, the analysis of the complexities of psychiatric treatments exist. Support for this limitation on the use of illness and decisions regarding the risks and benefits of exist placebos stems, in part, from the Declaration of Helsinki ing compounds compared with novel agents would be lim (1), which declares that human research subjects have a right ited by only having the existing active comparison agent as to therapeutically proven methods and treatments when a reference point (20,27). Nevertheless, use of placebo agents is widespread that brief placebo periods may be conducted safely, particu throughout medical research (18,19). Chapter 35: Ethics of Neuropsychiatric Research 477 Drug Withdrawal Studies Challenge Studies Medication discontinuation studies in psychiatric research Another of the controversial research techniques that has have become another point of ethical contention. The scien undergone public scrutiny are provocation or 'challenge' tific rationale for drug discontinuation has included the de- studies. These terms refer to experiments in which patients sire to examine the pathophysiology and course of underly and sometimes healthy control subjects are exposed to drugs ing illnesses when patients are in an unmedicated state. Provocation Furthermore, assessment of the clinical and neurochemical studies are not unique to psychiatry. In general clinical re- effects of medications in some cases can be more legitimately search, provocation studies have been conducted to induce interpreted in a given individual after a period of drug wash- pain, nausea and/or vomiting, bronchoconstriction, tachy out, as the potential therapeutic or adverse effects of the cardia, cognitive impairment, and even sepsis (44). These initial treatment may present a confounding variable, mak studies share the same basic goal of allowing investigators ing interpretation difficult (20,30). Although widely used in medical re- proach has been raised both in the scientific community search, their use in studies examining psychiatric illnesses and in the lay press. For example, recent literature suggests seems to have captured the interest of lay persons, advocacy that chronic patients may have a poorer response to treat groups, the media, and even policy makers. One theory is ment or deleterious effects should they be taken off medica that these types of studies may be more common in neuro tion and experience relapses (31–33).