Safety of dobutamine or adenosine stress cardiac magnetic resonance imaging in patients with left ventricular thrombus

BACKGROUND

Left ventricular (LV) thrombus formation is a common but potentially serious complication, typically occurring after myocardial infarction. Due to perceived high thromboembolic risk and lack of safety data, stress cardiac magnetic resonance (CMR) imaging especially with dobutamine is usually avoided despite its high diagnostic yield. This study aimed to investigate the characteristics, safety and outcome of patients with LV thrombus undergoing dobutamine or vasodilator stress CMR.

METHODS

Patients undergoing stress CMR with concomitant LV thrombus were retrospectively included. Risk factors, comorbidities, and previous embolic events were recorded. Periprocedural safety was assessed for up to 48 h following the examination. Major adverse cardiac events (MACE) 12 months before the diagnosis were compared to 12 months after the exam and between patients and a matched control group. Additionally, patients were followed up for all-cause mortality.

RESULTS

95 patients (78 male, 65 ± 10.7 years) were included. Among them, 43 patients underwent dobutamine (36 high-dose, 7 low-dose) and 52 vasodilator stress CMR. Periprocedural safety was excellent with no adverse events. During a period of 24 months, 27 MACE (14.7%) occurred in patients and controls with no statistical difference between groups. During a median follow-up of 33.7 months (IQR 37.6 months), 6 deaths (6.3%) occurred. Type of stress agent, thrombus mobility, or protrusion were not correlated to embolic events or death.

CONCLUSION

The addition of a stress test to a CMR exam is safe and does increase the generally high cardioembolic event rate in LV thrombus patients. Therefore, it is useful to support reperfusion decision-making.

Safety, accuracy, and prediction of prognosis in patients with end-stage chronic kidney disease undergoing dobutamine stress cardiac magnetic resonance imaging

Introduction

Advanced chronic kidney disease (CKD) is an independent risk factor for coronary artery disease (CAD). Due to its unique uremia-derived pathophysiology of atherosclerosis and the limitations of using potentially harmful contrast agents, the best non-invasive approach to assess CAD in these patients remains unclear. We sought to investigate the accuracy, safety, and prognosis of patients with severe CKD undergoing dobutamine stress cardiac magnetic resonance imaging (CMR).

Materials and methods

In this retrospective, single-center study, patients on dialysis or with a glomerular filtration rate of <15 ml/min/1.73 m2 who underwent dobutamine stress CMR were included. A rest and stress wall motion analysis was performed using dobutamine/atropine as stressor. The target heart rate was 85% of the maximum heart rate. Periprocedural adverse events and 1-year follow-up data were obtained.

Results

A total of 176 patients (127 men, 49 women) with a mean age of 60.9 ± 14.7 years were included, of which 156 patients were on permanent dialysis. Short-term symptoms such as angina or shortness of breath during stress CMR were frequent (22.1%), but major complications were rare (one patient with myocardial infarction, 0.6%). The 1-year event rate was high (16.4%) with a significant independent correlation to reduced ejection fraction at rest (p = 0.037) and failure to achieve the target heart rate (p = 0.029). The overall accuracy for predicting significant CAD was good (sensitivity of 71.4%, specificity of 98.4%) and excellent if the target heart rate was achieved (83.3%, 97.9%). A negative stress CMR was highly predictive for the absence of major adverse cardiac event or any coronary revascularization during the 1-year follow-up (negative predictive value of 95.0%).

Discussion

Dobutamine stress CMR is a safe and accurate diagnostic imaging technique in patients at advanced stages of chronic kidney disease. A reduced ejection fraction and the inability to reach the target heart rate are independent predictors of a poor outcome.

Safety of Stress Cardiac Magnetic Resonance in Patients With Moderate to Severe Aortic Valve Stenosis

BACKGROUND

Dobutamine and adenosine stress cardiac magnetic resonance (CMR) imaging is relatively contraindicated in patients with moderate to severe aortic valve stenosis (AS). We aimed to determine the safety of dobutamine and adenosine stress CMR in patients with moderate to severe AS.

METHODS

In this retrospective study patients with AS who underwent either dobutamine or adenosine stress CMR for exclusion of obstructive coronary artery disease were enrolled. We recorded clinical data, CMR and echocardiography findings, and complications as well as minor symptoms. Patients with AS were compared to matched individuals without AS.

RESULTS

A total of 187 patients with AS were identified and compared to age-, gender- and body mass index-matched 187 patients without AS. No severe complications were reported in the study nor the control group. The reported frequency of non-severe complications and minor symptoms were similar between the study and the control groups. Nineteen patients with AS experienced non-severe complications or minor symptoms during dobutamine stress CMR compared to eighteen patients without AS (p = 0.855). One patient with AS and two patients without AS undergoing adenosine stress CMR experienced minor symptoms (p = 0.562). Four examinations were aborted because of chest pain, paroxysmal atrial fibrillation and third-degree atrioventricular block. Inducible ischaemia, prior coronary artery bypass grafting, prior stroke and age were associated with a higher incidence of complications and minor symptoms.

CONCLUSIONS

Moderate to severe AS was not associated with complications during CMR stress test. The incidence of non-severe complications and minor symptoms was greater with dobutamine.

The impact of Wilson disease on myocardial tissue and function: a cardiovascular magnetic resonance study

BACKGROUND

Systemic effects of altered serum copper processing in Wilson Disease (WD) might induce myocardial copper deposition and consequently myocardial dysfunction and structural remodeling. This study sought to investigate the prevalence, manifestation and predictors of myocardial tissue abnormalities in WD patients.

METHODS

We prospectively enrolled WD patients and an age-matched group of healthy individuals. We applied cardiovascular magnetic resonance (CMR) to analyze myocardial function, strain, and tissue characteristics. A subgroup analysis of WD patients with predominant neurological (WD-neuro+) or hepatic manifestation only (WD-neuro-) was performed.

RESULTS

Seventy-six patients (37 years (27-49), 47% women) with known WD and 76 age-matched healthy control subjects were studied. The prevalence of atrial fibrillation in WD patients was 5% and the prevalence of symptomatic heart failure was 2.6%. Compared to healthy controls, patients with WD had a reduced left ventricular global circumferential strain (LV-GCS), and also showed abnormalities consistent with global and regional myocardial fibrosis. WD-neuro+ patients presented with more severe structural remodeling and functional impairment when compared to WD-neuro- patients.

CONCLUSIONS

In a large cohort, WD was not linked to a distinct cardiac phenotype except CMR indexes of myocardial fibrosis. More research is warranted to assess the prognostic implications of these findings.

TRIAL REGISTRATION

This trial is registered at the local institutional ethics committee (S-188/2018).

[Bed capacity management in times of the COVID-19 pandemic : A simulation-based prognosis of normal and intensive care beds using the descriptive data of the University Hospital Augsburg]

BACKGROUND

Following the regional outbreak in China, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread all over the world, presenting the healthcare systems with huge challenges worldwide. In Germany the coronavirus diseases 2019 (COVID-19) pandemic has resulted in a slowly growing demand for health care with a sudden occurrence of regional hotspots. This leads to an unpredictable situation for many hospitals, leaving the question of how many bed resources are needed to cope with the surge of COVID-19 patients.

OBJECTIVE

In this study we created a simulation-based prognostic tool that provides the management of the University Hospital of Augsburg and the civil protection services with the necessary information to plan and guide the disaster response to the ongoing pandemic. Especially the number of beds needed on isolation wards and intensive care units (ICU) are the biggest concerns. The focus should lie not only on the confirmed cases as the patients with suspected COVID-19 are in need of the same resources.

MATERIAL AND METHODS

For the input we used the latest information provided by governmental institutions about the spreading of the disease, with a special focus on the growth rate of the cumulative number of cases. Due to the dynamics of the current situation, these data can be highly variable. To minimize the influence of this variance, we designed distribution functions for the parameters growth rate, length of stay in hospital and the proportion of infected people who need to be hospitalized in our area of responsibility. Using this input, we started a Monte Carlo simulation with 10,000 runs to predict the range of the number of hospital beds needed within the coming days and compared it with the available resources.

RESULTS

Since 2 February 2020 a total of 306 patients were treated with suspected or confirmed COVID-19 at this university hospital. Of these 84 needed treatment on the ICU. With the help of several simulation-based forecasts, the required ICU and normal bed capacity at Augsburg University Hospital and the Augsburg ambulance service in the period from 28 March 2020 to 8 June 2020 could be predicted with a high degree of reliability. Simulations that were run before the impact of the restrictions in daily life showed that we would have run out of ICU bed capacity within approximately 1 month.

CONCLUSION

Our simulation-based prognosis of the health care capacities needed helps the management of the hospital and the civil protection service to make reasonable decisions and adapt the disaster response to the realistic needs. At the same time the forecasts create the possibility to plan the strategic response days and weeks in advance. The tool presented in this study is, as far as we know, the only one accounting not only for confirmed COVID-19 cases but also for suspected COVID-19 patients. Additionally, the few input parameters used are easy to access and can be easily adapted to other healthcare systems.

P5267Cardiac tissue characterization in patients with wilsons disease using magnetic resonance imaging

Introduction

Wilson's disease (WD) is a rare autosomal recessive copper disorder with limited excretion of excess copper into the bile. Primary symptoms are hepatic or neurological. However, the clinical range of WD is wide and can result in cardiac symptoms as well. Previous studies revealed a higher incidence of heart failure in WD patients compared to the rest of the population.

Purpose

Cardiac magnetic resonance imaging (CMR) is used to identify the typical features of several systemic disorders with excessive myocardial deposition of substrates. The aim of this study was to perform a cardiac tissue characterization in WD patients by using CMR and to identify subgroups of WD patients with reduced ejection fraction (EF).

Methods

Patients with known WD using Ferenci-Score were included in this prospective study. WD patients were referred to 1.5 Tesla CMR. The following CMR protocol was performed; Cine-images, T1-, T2- and T2*-Mapping, fast-SENC strain and late gadolinium enhancement (LGE). Fast-SENC strain measurements were compared with values from healthy individuals scanned at the center.

Results

43 patients (age 38.7±12.8 years, 20 female, BMI 23.80 (17.4–33.1)) with WD could be identified and were evaluated with CMR. CMR revealed normal left ventricular (LV) EF (62.4±5.4%) and right ventricular (RV) EF (64.4±7.1%) overall. However, three patients (7%), who suffered primarily from neurological symptoms, were found to have mildly reduced LV-EF (46.5%, 51%, and 53.5%). Strain analysis revealed significantly reduced LV global circumferential strain (GCS) overall compared to healthy individuals (WD (%): −19.2 2.7; control (%): −20.71±1.5, p<0.05). Patients with primarily hepatic symptoms (WD-h) did not show reduced strain measurements compared to the control group. Patients suffering from primarily neurological symptoms (WD-n) showed significantly reduced LV GCS compared to healthy individuals (WD-n (%): −18.3±3.1; control (%): −20.7±1.5, p<0.05) and RV GCS (WD-n (%): −17.5±3.0; control (%): −19.2±1.8, p<0.05). Also, LV GCS in WD-n was significantly reduced compared to WD-h (WD-n (%): −18.3±3.1; WD-h (%): −20.0±2.0). Furthermore, there were no significant differences between the two subgroups, besides a significant thicker lateral wall in patients with WD-n (WD-n (mm): 7 (5–9); WD-h (mm): 6 (5–8), p<0.05). T1-, T2- and T2*-Mapping did not show any pathological pattern and were overall in the normal range (T1: 1020±30ms; T2: 52.9±3.0ms; T2*: 38.4±5.6ms). Epicardial LGE was present in 1 patient.

Conclusion

Cardiac tissue characterization was performed in WD patients using CMR. Reduced EF, LV and RV GCS have been detected in patients with primarily neurological symptoms. Cardiovascular autonomic dysfunction in this subgroup could be a reason for the reduced biventricular strain. It is unknown if reduced circumferential strain influences the prognosis of WD patients, which should be investigated in further studies.

Education in end-of-life care: bridging disciplinary and institutional boundaries

This paper describes the development of an interdisciplinary, interinstitutional seminar in palliative care for South Dakota students in medicine, nursing, pharmacy, chaplaincy, and social work. Student outcomes from six seminars conducted during 2001-2004 are reported, and recommendations for future educational efforts are outlined.

Intraoperative end-tidal carbon dioxide values and derived calculations correlated with outcome: prognosis and capnography

OBJECTIVE

To determine how much information concerning resuscitation and outcome is provided by the end-tidal CO2 and derived variables obtained during surgery.

DESIGN

Retrospective chart review.

SETTING

Emergency hospital operating room.

PATIENTS

One hundred critically ill or injured patients requiring major surgery and having a mortality rate of 41%.

INTERVENTIONS

Standard intraoperative monitoring, including continuous capnography, plus arterial blood gas analyses every 1 to 1.5 hrs during surgery.

MEASUREMENTS AND MAIN RESULTS

There was only a fair correlation between the PaCO2 and end-tidal CO2 (r2 = .14). The mortality rates in these patients were highest in those patients who had the lowest end-tidal CO2 values, the highest arterial to end-tidal CO2 differences, and the highest estimated alveolar deadspace fraction. A persistent end-tidal CO2 of < or = 28 torr (< or = 3.8 kPa) was associated with a mortality rate of 55% (vs. 17% in those patients with a higher end-tidal CO2). The mortality rate was also increased in patients with a persistent arterial to end-tidal CO2 difference of > or = 8 torr (> or = 1.1 kPa) (58% vs. 23%).

CONCLUSIONS

End-tidal CO2 and derived values should be monitored closely in critically ill or injured patients. Efforts should be made--by increasing cardiac output and core temperature and by adjusting ventilation as needed--to maintain the end-tidal CO2 at > or = 29 torr (> or = 3.9 kPa) and the arterial to end-tidal CO2 difference at < or = 7 torr (< or = 1.0 kPa).

End-diastolic volume versus pulmonary artery wedge pressure in evaluating cardiac preload in trauma patients

OBJECTIVE

To evaluate the relative accuracy of right ventricular end-diastolic volume index (RVEDVI) and pulmonary artery wedge pressure (PAWP) for determining cardiac preload.

METHODS

A modified pulmonary artery catheter was used to determine RVEDVI, PAWP, and CI 238 times in 32 trauma patients.

RESULTS

The initial mean values included cardiac index (CI) = 3.4 +/- 1.3 L/min/m2, PAWP = 14.8 +/- 6.6 mm Hg, and RVEDVI = 99 +/- 40 mL/m2. Cardiac index correlated better with RVEDVI (r = 0.6440; p < 0.001) than with PAWP (r = 0.1068) or CVP (r = 0.1604). In 84 studies in 19 patients, the PAWP was high (19+ mm Hg) in spite of an RVEDVI that was low (< 90 mL/m2) in 22 (26%) or mid-range (90-140 mL/m2) in 49 (58%) of these. In addition, in 12 studies a high RVEDVI (> 140 mL/m2) existed with a relatively low PAWP (< 12 mm Hg). Thus, in 83 (35%) of the studies, PAWP provided information different from the RVEDVI. Of 65 instances in which preload was increased, CI "responded" (> or = 20%) in 26 (40%). The incidence of a response was not affected by the PAWP; however, responses with a RVEDVI of < 90, 90-140, or > 140 mL/m2 were 64%, 27%, and 0 (p < 0.001).

CONCLUSION

The RVEDVI more accurately predicted preload recruitable increases in CI than did the PAWP.

Food labeling

In June 1990, the American Diabetes Association approved a food labeling position statement (1) that emphasized the following four general points: 1) food labeling must be truthful, meaningful, understandable, and complete; 2) no food should be designated or promoted as nutritionally good, bad, healthful, or unhealthful for people with diabetes; 3) education, based on principles of good nutrition and use of food labels, is essential for people with diabetes; and 4) specific recommendations for label inclusions.

Extended investigation of the substrate specificity of dipeptidyl peptidase IV from pig kidney

The substrate specificity of dipeptidyl peptidase IV (dipeptidyl peptide hydrolase, EC 3.4.14.5) from pig kidney was investigated, using a series of substrates, in which the amino-acid residue in position P1, a structural derivative of proline, was altered with respect to ring size and substituents. It was demonstrated that dipeptidyl peptidase IV hydrolyses substrates of the type Ala-X-pNA, where X is proline (Pro), (R)-thiazolidine-4-carboxylic acid (Thz), (S)-pipecolic acid (Pip), (S)-oxazolidine-4-carboxylic acid (Oxa), or (S)-azetidine-2-carboxylic acid (Aze). The ring size and ring structure of the residue in the P1 position influence the rate of enzyme-catalysed hydrolysis of the substrate. The highest kcat value (814 s-1) was found for Ala-Aze-pNA. In contrast, the kcat value for Ala-Pro-pNA is nearly 55 s-1. With all substrates of this series, the rate-limiting step of the hydrolysis by dipeptidyl peptidase IV is the deacylation reaction. Compounds of substrate-like structure, in which the P2 residue has an R-configuration, are not hydrolysed by dipeptidyl peptidase IV.

Are diprotin A (Ile-Pro-Ile) and diprotin B (Val-Pro-Leu) inhibitors or substrates of dipeptidyl peptidase IV?

Dipeptidyl peptidase IV preferably hydrolyzes peptides and proteins with a penultimate proline residue. Umezawa and co-workers (Umezawa et al. (1984) J. Antibiotics 37, 422-425) reported that diprotin A (Ile-Pro-Ile) and diprotin B (Val-Pro-Leu) are inhibitors for dipeptidyl peptidase IV. We could show that both compounds as well as other tripeptides with a penultimate proline residue are substrates for dipeptidyl peptidase IV. An apparent competitive inhibition by those compounds is a kinetic artifact due to the substrate-like structure of such tripeptides.

Purification and characterization of prolyl endopeptidase from pig brain

The prolyl endopeptidase from pig brain was purified to homogeneity according to SDS-gel electrophoresis and visualization with the silver staining procedure. The molecular weight of prolyl endopeptidase was estimated as 70 kDa, and the isoelectric point as 4.9. The molecular properties of prolyl endopeptidase from pig brain are therefore similar to those of prolyl endopeptidases from other mammalian tissues. Diisopropylfluorophosphate, diethylpyrocarbonate and p-chloromercuribenzoic acid are strong irreversible inhibitors of prolyl endopeptidase from pig brain. We showed that diisopropylfluorophosphate und diethylpyrocarbonate act as competitive inhibitors with respect to substrate. Therefore it is assumed that at least one serine and one histidine residue are located at the active site of this enzyme. This result supports the assumption that the prolyl endopeptidase from pig brain is a typical serine protease. Substance P, thyreoliberin, beta-casomorphin-5 and morphiceptin are hydrolysed by prolyl endopeptidase in vitro.

[Application of dipeptidylpeptidase IV in formation of the peptide bond]

According to the increasing importance of enzyme catalysed peptide synthesis the capability of the protease dipeptidyl peptidase IV is shown to form the peptide bond. To our best knowledge, it's the first time that has been used successfully proline as one of the amino acids. The formation of the peptide bond is kinetically controlled. Free amino acids have been used as nucleophiles. The reaction media contain 50 vol.-% glycerol. A first approach to a kinetic treatment is shown.

Empirical identification of techniques useful for counseling patients with diabetes

Instruction for counseling patients with diabetes is based primarily on intuition from clinical experience and inferences from related research. To identify potentially useful counseling techniques, we elicited descrip tions of effective skills from analogue patients (APs) who played the roles of diabetic patients in practice counseling sessions with nurse and dietitian course participants. APs were first- and second-year graduate students in psychology, trained to play one offour patient roles. After each role play, the APs provided written feedback regarding "three things the counselor did that I felt best about. " The two most frequently cited behaviors were (1) consid ering needs other than those related to diabetes in making adherence recommendations, and (2) providing clear, concrete advice. Further research with actual diabetic patients is needed to validate the present findings and to explore such ambiguities as when to give advice versus when to ask questions.

Mechanism of proline-specific proteinases: (I) Substrate specificity of dipeptidyl peptidase IV from pig kidney and proline-specific endopeptidase from Flavobacterium meningosepticum

The substrate specificity of dipeptidyl peptidase IV (dipeptidyl peptide hydrolase, EC 3.4.14.5) from pig kidney and proline-specific endopeptidase from Flavobacterium meningosepticum, was investigated with a series of N-terminal unprotected (dipeptidyl peptidases IV) and succinylated dipeptidyl-p-nitroanilides (proline-specific endopeptidase). Both enzymes are specific for the S configuration of the amino-acid residue in P1 and P2 position if the penultimate residue is proline. In the case of alanine substrates (Ala in P1, dipeptidyl peptidase IV hydrolyzes such compounds where the configuration of the P2 residue is R. The penultimate residue with dipeptidyl peptidase IV can be, beside proline and alanine, dehydroproline, hydroxyproline and pipecolic acid. Proline substrates (Pro in P1) with an R configuration in P2 are inhibitors of the hydrolysis of proline substrates with an S,S configuration in an uncompetitive (dipeptidyl peptide IV) or mixed inhibition type (proline-specific endopeptidase). Derivatives of Gly-Pro-pNA where the N-terminal amino group is methylated are hydrolyzed by dipeptidyl peptidase IV.

Molecular interactions in intermediate and transition states in the self-stimulated inhibition of enzymes

Di-isopropyl fluorophosphate (DFP) and other organophosphorus inhibitors recruit the catalytic power of their target enzymes: the enzyme catalyzes its own irreversible phosphorylation. The magnitude of the catalytic acceleration can approach the factor by which the enzyme catalyzes its own acylation by natural substrates. The reaction of DFP with five serine proteases [chymotrypsin, elastase, dipeptidyl peptidase IV (DP IV), subtilisin and thermitase] exhibits in all cases the same pH dependence as does enzyme acylation by natural substrates. Chymotrypsin and elastase form a "fast" class of enzymes which react about ten-fold faster than the other three "slow" enzymes. All enzymes show k(HOH)/k(DOD) of about 2 but the proton inventory indicates one-proton character for "slow" enzymes and multiproton character for "fast" enzymes. Enthalpies of activation are about 33 kJ/mol (subtilisin, "slow") and 10 kJ/mol (elastase, "fast"). Entropies of activation are about -120 J.T-1.mol-1 (subtilisin, "slow") and -175J.T-1.s-1 (elastase, "fast"; T = temperature in K).

Kinetic investigation of the hydrolysis of aminoacyl p-nitroanilides by dipeptidyl peptidase IV from human and pig kidney

Dipeptidyl peptidase IV (dipeptidyl-peptide hydrolase, EC 3.4.14.5), an enzyme that participates in the catabolism of bradykinin and Substance P as well as the post-translational processing of various other peptides, has been purified from human and pig kidney. The assay reaction involved the cleavage of p-nitroaniline (pNA) from various dipeptidyl p-nitroanilides. The specific activities of the human and pig enzyme (with Gly-Pro-pNA at pH 7.6) were 49.2 and 45.8, respectively. The dependence of initial reaction velocity on substrate concentration was determined for a variety of dipeptidyl p-nitroanilides over the concentration range 0.05 to 2.0 mM. Most of the substrates tested produced significant non-hyperbolic behavior for the function v vs. S at concentrations above 0.5 mM. As to differences between the two enzymes, the pig enzyme exhibited featureless (i.e., hyperbolic) behavior with Glu-Pro-pNA concentrations as high as 2.0 mM, whereas the human enzyme produced significant non-hyperbolic behavior for the function v vs. S, beginning at S = 0.4 mM. Thus, the human and pig dipeptidyl peptidases IV are kinetically distinct enzyme forms.

The conformation around the peptide bond between the P1- and P2-positions is important for catalytic activity of some proline-specific proteases

Proline-containing dipeptidyl-4-nitroanilides have been synthesised and subjected to dipeptidyl peptidase IV-catalysed hydrolysis at high enzyme concentrations to collect information on the conformational specificity of the enzyme active site for a nonscissile bond. Descriptions of the biphasic kinetics were carried out in terms of cis/trans interconversion of the substrates. The results show that the enzyme can cleave only the trans-conformation of the substrate. The competitive inhibition by Gly-Pro-OH and Ala-Pro-OH is also specific for the trans form of the dipeptides. The interpretation of the results obtained from these kinetic studies has led to proposals for the stepwise cleavage of biologically active peptides like substance P and beta-casomorphine by dipeptidyl peptidase IV.

[Dipeptidyl peptidase activities in various organs of the Wistar rat]

Using Gly-Pro-pNa as a substrate, the authors photometrically determined the dipeptidyl peptidase activity in organic homogenates and serum of Wistar rats at two pH values. The activity of the serine peptidase DP IV was measured at pH = 7.6; a mixed activity (DP MA) which is composed of the activities of several dipeptidyl peptidases, at pH = 5.0. Particularly high DP IV activities were determined in the kidney, lung, adrenal gland, liver and aortic arch, the differences among the enzyme activities measured in the single organic homogenates at pH = 5.0 being smaller. The DP IV activities and the values found for DP MA in the structures of the nervous system were in general lower. Maximum DP IV values were measured in the spinal ganglion, cerebral cortex and spinal bulb; and maximum DP MA values, in the hypothalamus, cerebellum and cerebral cortex. The results obtained are discussed from the aspects of the participation of these enzymes in peptidergic regulatory mechanisms and of a possible relation to blood-pressure regulation.