The benefits of on-site cytology with ultrasound-guided fine needle aspiration in a one-stop neck lump clinic

INTRODUCTION

In the National Institute for Health and Clinical Excellence (NICE) guidance on cancer services published in 2004, it was recommended that specialist clinics should be set up for the assessment of patients with neck lumps, structured in a similar way to one-stop breast lump clinics with a cytopathologist present and preferably ultrasound guidance. The aim of this study was to audit the performance of ultrasound-guided fine needle aspiration (FNA) with on-site cytology in a one-stop neck lump clinic at The Royal Liverpool University Hospital.

PATIENTS AND METHODS

Data were collected between November 2008 and May 2009 (7 months). Details of the adequacy rate for the FNA were recorded and whether multiple passes were required. The likely adequacy rate if ultrasound guidance was not available was also calculated.

RESULTS

A total of 274 patients were included in the audit. Of these, 227 (83%) patients required a single pass for adequate diagnostic material. Of the remaining, 45 (16%) required two passes and 2 (1%) required three passes. The overall sample inadequacy rate was 11 of 274 (4%). From these results, it could be predicted that, if immediate cytological evaluation was unavailable, the inadequacy rate would have been 41 of 274 (15%).

CONCLUSIONS

This audit has illustrated the benefits of a one-stop clinic with on-site cytology in providing a rapid diagnostic head and neck cancer service.

The benefits of on-site cytology with ultrasound-guided fine needle aspiration in a one-stop neck lump clinic

INTRODUCTION

In the National Institute for Health and Clinical Excellence (NICE) guidance on cancer services published in 2004, it was recommended that specialist clinics should be set up for the assessment of patients with neck lumps, structured in a similar way to one-stop breast lump clinics with a cytopathologist present and preferably ultrasound guidance. The aim of this study was to audit the performance of ultrasound-guided fine needle aspiration (FNA) with on-site cytology in a one-stop neck lump clinic at The Royal Liverpool University Hospital.

PATIENTS AND METHODS

Data were collected between November 2008 and May 2009 (7 months). Details of the adequacy rate for the FNA were recorded and whether multiple passes were required. The likely adequacy rate if ultrasound guidance was not available was also calculated.

RESULTS

A total of 274 patients were included in the audit. Of these, 227 (83%) patients required a single pass for adequate diagnostic material. Of the remaining, 45 (16%) required two passes and 2 (1%) required three passes. The overall sample inadequacy rate was 11 of 274 (4%). From these results, it could be predicted that, if immediate cytological evaluation was unavailable, the inadequacy rate would have been 41 of 274 (15%).

CONCLUSIONS

This audit has illustrated the benefits of a one-stop clinic with on-site cytology in providing a rapid diagnostic head and neck cancer service.

EUELC project: a multi-centre, multipurpose study to investigate early stage NSCLC, and to establish a biobank for ongoing collaboration

The European Early Lung Cancer (EUELC) project aims to determine if specific genetic alterations occurring in lung carcinogenesis are detectable in the respiratory epithelium. In order to pursue this objective, nonsmall cell lung cancer (NSCLC) patients with a very high risk of developing progressive lung cancer were recruited from 12 centres in eight European countries: France, Germany, southern Ireland, Italy, the Netherlands, Poland, Spain and the UK. In addition, NSCLC patients were followed up every 6 months for 36 months. A European Bronchial Tissue Bank was set up at the University of Liverpool (Liverpool, UK) to optimise the use of biological specimens. The molecular-pathological investigations were subdivided into specific work packages that were delivered by EUELC Partners. The work packages encompassed mutational analysis, genetic instability, methylation profiling, expression profiling utilising immunohistochemistry and chip-based technologies, as well as in-depth analysis of FHIT and RARbeta genes, the telomerase catalytic subunit hTERT and genotyping of susceptibility genes in specific pathways. The EUELC project engendered a tremendous collaborative effort, and it enabled the EUELC Partners to establish protocols for assessing molecular biomarkers in early lung cancer with the view to using such biomarkers for early diagnosis and as intermediate end-points in future chemopreventive programmes.

BSCC Code of Practice--fine needle aspiration cytology

The British Society for Clinical Cytology Code of Practice on fine needle aspiration cytology complements that on exfoliative cytopathology, which was published in the last issue (Cytopathology 2009;20:211-23). Both have been prepared with wide consultation within and outside the BSCC and have been endorsed by the Royal College of Pathologists. A separate code of practice for gynaecological cytopathology is in preparation. Fine needle aspiration (FNA) cytology is an accepted first line investigation for mass lesions, which may be targeted by palpation or a variety of imaging methods. Although FNA cytology has been shown to be a cost-effective, reliable technique its accurate interpretation depends on obtaining adequately cellular samples prepared to a high standard. Its accuracy and cost-effectiveness can be seriously compromised by inadequate samples. Although cytopathologists, radiologists, nurses or clinicians may take FNAs, they must be adequately trained, experienced and subject to regular audit. The best results are obtained when a pathologist or an experienced and trained biomedical scientist (cytotechnologist) provides immediate on-site assessment of sample adequacy whether or not the FNA requires image-guidance. This COP provides evidence-based recommendations for setting up FNA services, managing the patients, taking the samples, preparing the slides, collecting material for ancillary tests, providing rapid on-site assessment, classifying the diagnosis and providing a final report. Costs, cost-effectiveness and rare complications are taken into account as well as the time and resources required for quality control, audit and correlation of cytology with histology and outcome. Laboratories are expected to have an effective quality management system conforming to the requirements of a recognised accreditation scheme such as Clinical Pathology Accreditation (UK) Ltd.

The Dundee University Scottish Keratoconus study: demographics, corneal signs, associated diseases, and eye rubbing

AIM

To investigate and correlate the corneal, refractive, topographic and familial characteristics of a large cohort with keratoconus.

METHODS

Prospective observational study of 200 consecutive patients presenting with keratoconus during the 4 year-period 1997-2000. Subjects were examined at enrolment and at a final review. Data were collected on demographic characteristics, referral route, symptoms, refractive correction, eye rubbing, family history, medical history, slit-lamp biomicroscopic corneal signs, and computerized corneal topography.

RESULTS

Mean age at enrolment was 30.9+/-10.4 (range, 12.2-72) years (N=200, 62.5% male, 93% white Caucasian) with a 5% family history of keratoconus. Atopic diseases included asthma (23%), eczema (14%), and hay fever (30%). Only 9% wore contact lenses before referral. Mean follow-up was 1004 days +/-282 (range, 390-1335) and 9.7+/-8.9 (range, 1.1-60) years from diagnosis. The mean simulated K1 corneal power at enrolment was 51.74+/-5.36 (range, 42.59-67.32) D and 88.5% exhibited bilateral keratoconus. Fifty-three (15%) topographically confirmed cones exhibited no clinical corneal signs at presentation. At enrollment, 56% had a pachymetry <0.480 mm increasing to 77% at final review. Forty-eight percent of subjects reported significant eye rubbing and there was a highly statistically significant difference (two sample t-test P=0.018) between keratoconus and control groups. TMS-2 axial corneal power was strongly associated with corneal scarring and age at diagnosis. The size of the scarring effect was 2.2 D (95% confidence interval (CI) 1.34, 3.06).

CONCLUSIONS

This study provides an overview of a large population with keratoconus highlighting presenting features and clinical and topographic progression over a 4 year-period.

Ultrasound-guided fine needle aspiration cytology in the diagnosis and management of thyroid nodules

OBJECTIVE

To examine the accuracy of fine needle aspiration cytology (FNAC) in the diagnosis of thyroid nodules and compare the inadequacy rates for ultrasound-guided and freehand FNAC.

METHODS

A retrospective study of 434 patients with thyroid nodules who underwent diagnostic FNAC over a 2-year period. Cytological diagnoses have been compared with the histological assessment of resection specimens in 69 cases.

RESULTS

The inadequacy rate was significantly lower from ultrasound guided FNAC (24/373 cases, 6.4%) than from freehand FNAC (8/61 cases, 13.1%) (P = 0.043). Seventy-six percentage of patients had a non-neoplastic cytological diagnosis and, after multidisciplinary review, the patients were reassured and assigned to clinical follow-up. Sixty-seven patients had a resection for cytological appearances consistent with non-neoplastic disease (n = 34), suspicious of follicular neoplasia (n = 23), or suspicious of malignancy (n = 10), and two patients had resections following inadequate cytology with ultrasound appearances suspicious of a neoplasm. The overall accuracy of FNAC analysis for malignancy was 97.0%, with sensitivity 83.3%, specificity 98.0%, positive predictive value 71.4% and negative predictive value 98.4%. The overall accuracy of FNAC analysis for the prediction of neoplasia was 97.5%, with sensitivity 80.5%, specificity 97.8%, positive predictive value 89.2% and negative predictive value 95.9%. Difficulties in cytological diagnosis were associated with lymphoid infiltrates and with degenerative changes in follicular adenomas.

CONCLUSION

Ultrasound-guided FNAC has a significantly lower yield of inadequate aspirates than palpable FNAC. The ability of FNAC to predict neoplasia in 89% patients and to exclude neoplasia in 95.9% patients makes an important contribution to the multidisciplinary assessment of patients.

Impairment of cardiac function in hypertensive patients with Type 2 diabetes: a LIFE study

AIMS

Type 2 diabetic patients with hypertension have an increased left ventricular (LV) mass and impaired cardiac function compared to hypertensive patients without diabetes. However, it is unknown if the impaired cardiac function can be explained solely by LV hypertrophy, or is independently related to diabetes. The aim of the present study was to compare LV function between diabetic and non-diabetic hypertensive patients with electrocardiographic LV hypertrophy.

METHODS

In 937 patients participating in the LIFE echocardiographic substudy, all echocardiograms were centrally evaluated by a core reading centre measuring LV mass, systolic and diastolic LV function. Known diabetes was present in 105 patients.

RESULTS

Left ventricular mass was similar in diabetic and non-diabetic patients. Endocardial systolic LV function, estimated by LV ejection fraction, was reduced and indices of midwall systolic LV function were impaired in the diabetic patients. Diastolic LV filling pattern was impaired and arterial stiffness, measured by pulse pressure/stroke index, was increased in diabetic patients.

CONCLUSIONS

Systolic and diastolic LV function in hypertensive patients with electrocardiographic LV hypertrophy and diabetes are impaired independent of LV mass, most likely reflecting the adverse effects of diabetes per se.

Angiotensin receptor blockers: evidence for preserving target organs

Hypertension is a major problem throughout the developed world. Although current antihypertensive treatment regimens reduce morbidity and mortality, patients are often noncompliant, and medications may not completely normalize blood pressure. As a result, current therapy frequently does not prevent or reverse the cardiovascular remodeling that often occurs when blood pressure is chronically elevated. Blockade of the renin-angiotensin system (RAS) is effective in controlling hypertension and treating congestive heart failure. Both angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) inhibit the activity of the RAS, but these two classes of antihypertensive medications have different mechanisms of action and different pharmacologic profiles. Angiotensin-converting enzyme inhibitors block a single pathway in the production of angiotensin II (Ang II). In addition, angiotensin I is not the only substrate for ACE. The ACE inhibitors also block the degradation of bradykinin that may have potential benefits in cardiovascular disease. Bradykinin is, however, the presumed cause of cough associated with ACE inhibitor therapy. Data from clinical trials on ACE inhibitors serve to support the involvement of the RAS in the development of cardiovascular disease. Angiotensin receptor blockers act distally in the RAS to block the Ang II type 1 (AT1) receptor selectively. Thus, ARBs are more specific agents and avoid many side effects. Experimental and clinical trials have documented the efficacy of ARBs in preserving target-organ function and reversing cardiovascular remodeling. In some instances, maximal benefit may be obtained with Ang II blockade using both ARBs and ACE inhibitors. This review describes clinical trials that document the efficacy of ARBs in protecting the myocardium, blood vessels, and renal vasculature.

First On-line beta-NMR on oriented nuclei: magnetic dipole moments of the (nup(1/2))(-1) 1/2(-) ground state in 67Ni and (pip(3/2))(+1) 3/2(-) ground state in 69Cu

The first fully on-line use of the angular distribution of beta emission in detection of NMR of nuclei oriented at low temperatures is reported. The magnetic moments of the single valence particle, intermediate mass, isotopes 67Ni(nup(-1)(1/2);1/2(-)) and 69Cu(pip(1)(3/2);3/2(-)) are measured to be +0.601(5) &mgr;(N) and +2.84(1) &mgr;(N), respectively, revealing only a small deviation from the neutron p(1/2) single-particle value in the former and a large deviation from the proton p(3/2) single-particle value in the latter. Quantitative interpretation is given in terms of core polarization and meson-exchange currents.

Vasculitic small bowel perforation masquerading as spontaneous bacterial peritonitis in a patient with decompensated liver disease

We report on a young patient with decompensated alcohol-induced liver disease (Child-Pugh score C) who presented with clinical, biochemical and radiological evidence suggestive of spontaneous bacterial peritonitis. She was however subsequently found to have multiple small bowel perforations, which were diagnosed only at laparotomy. The histology of the bowel showed evidence of vasculitis. This case illustrates two important points. Firstly, even if a patient has all the prerequisites to develop spontaneous bacterial peritonitis, a secondary cause of peritonitis (eg. bowel perforation or intra-abdominal abscess) must always be considered as a differential diagnosis and a repeat ascitic tap is mandatory after 48 h of antibiotic therapy to confirm a decrease in the white cell count. Secondly, it shows the rare co-existence of alcoholic liver disease and vasculitis.

Patterns of physician use of angiotensin converting enzyme inhibitors in the inpatient treatment of congestive heart failure

Randomized clinical trails have demonstrated that angiotensin-converting enzyme (ACE) inhibitors reduce mortality, improve symptoms, and decrease hospitalization rates in congestive heart failure (CHF) patients with impaired left ventricular systolic function. Guidelines from the Agency for Healthcare Policy and Research (AHCPR) endorse the use of ACE inhibitors in eligible CHF patients and note their underutilization in practice. Randomly selected records of 1,212 Medicare CHF patients in Louisiana, discharged between July 1993 and October 1993, were reviewed. Abstracted data were used to characterize practice patterns and pertinent clinical factors influencing current ACE inhibitor utilization by practicing physicians in eligible Medicare CHF patients admitted to acute care hospitals. A total of 1,133 patients admitted were discharged alive; mean age was 77.6 years (64% female; 68% white). One third of the patients (34%) were already receiving ACE inhibitors on admission; of these, 85% were discharged on ACE inhibitors. The remaining 66% of patients were not on an ACE inhibitor on admission; only 35% of these are documented to have been placed on an ACE inhibitor(s) at discharge. Overall, a significantly large number of CHF patient charts (48%) lacked documentation of LV systolic function assessments. On multivariate logistic regression modeling, the following key clinical variables were positively related to the prescription of ACE inhibitors: low ejection fraction, dyspnea and orthopnea, normal creatinine levels, high diastolic blood pressure, cardiomegaly, and increasing age. Among patients with low ejection fraction, factors contributing to not being discharged on ACE inhibitors included: high creatinine levels, history of myocardial infarction or ischemic heart disease, renal failure, and being African American. This study documents the underutilization of ACE inhibitors in patients with impaired left ventricular systolic function. Results suggest the need for increased physician-based educational efforts concerning the use of ACE inhibitors in CHF patients, and also for increasing left ventricular systolic function assessments and documentation of findings in patient charts.

The cost-effective way forward for the management of the patient with heart failure

Heart failure is a huge healthcare issue not only for clinicians but for healthcare managers also, with increasing pressure to demonstrate the cost-effectiveness of therapies especially for common chronic conditions. The cost-effectiveness of heart failure treatments relate to their effects on the progression of the disease, the associated quality of life for the patient, and the actual cost of the disease management. Direct costs are usually associated with hospitalization. Indirect costs, such as the loss of production through absence from work, are more difficult to determine. Studies such as CONSENSUS, SOLVD, SAVE and the Munich Heart Failure trial have all shown that angiotensin-converting enzyme inhibitors offer effective therapy in all these aspects. Non-pharmacological strategies that have also been shown to favorably influence both the costs and benefit include the addition of a nurse practitioner to assist in patient management.

The postmortem incidence of senile ecchymoses

Although senile ecchymoses are a well-recognized phenomenon on hospital wards, in patients who die in other settings they may be wrongly interpreted as bruising caused by physical assault. Therefore, we studied a total of 410 elderly (> 50 years of age) patients by a prospective examination of autopsy reports to elucidate their nature, including their general frequency, their anatomical distribution, and their physical appearance. We found a clear association with increasing age and a common distribution on the arms, rather than the neck or legs. One unique finding is that ecchymoses are related to place of residence, in that less mobile elderly persons are more likely to develop this condition, possibly as a result of lifting.

Duration of effects of isradipine during twice daily therapy in angina pectoris

Isradipine, a 1,4 dihydropyridine calcium channel antagonist, is a potent coronary artery dilator that increases coronary blood flow with little effect on cardiac contractility. Isradipine is an approved antihypertensive agent, but its antianginal effects have not been well documented. In this placebo-controlled, double-blind, parallel-group design study we evaluated the duration of effects and safety of isradipine 10 mg bid in male patients with chronic stable angina pectoris. Seventy-two patients experiencing moderately severe angina between 3 and 7.5 minutes during a standard Bruce exercise test received placebo in a single-blind manner for 8-14 days. Sixty-one of these patients had reproducible treadmill exercise test results on three consecutive occasions and underwent further exercise tests at 3, 8, and 12 hours after a placebo period. Patients were then randomized (double blind) to either placebo or isradipine 10 mg bid for 2 weeks. Symptom-limited exercise tests were repeated predose and at 3, 8, and 12 hours after the 0800 hour dose dosing. Exercise duration increased significantly from baseline (last qualifying test during the single-blind placebo therapy, i.e., 0800 hours predose at visit 4) in the isradipine group compared to the placebo group prior to the administration of the 0800 hour dose (i.e., 12 hours after the 2000 hour dose) by 51 vs. 18 seconds, p = 0.04; and after the administration of the 0800 hour dose at 3 hours by 78 vs. 29 seconds, p = 0.005; and at 8 hours by 54 vs. 18 seconds, p = 0.04. Similarly, statistical significance was achieved when exercise data were analyzed using visit 4 (single-blind placebo therapy) corresponding time points as baseline. At 12 hours after the 0800 hour dose, exercise tolerance did not increase significantly after isradipine compared to placebo. Time to 1-mm ST-segment depression increased significantly after isradipine at 3 hours post 0800 hour dose compared to placebo (87 vs. 7 seconds, p < 0.01) but not at the 0, 8, or 12-hour postdose time points, regardless of which baseline was used. Isradipine therapy did not affect the rate-pressure double product. A significant correlation between the mean increase in total exercise time and mean plasma isradipine concentration was also present (p = 0.0295). During double-blind treatment, drug-related adverse events were experienced by four patients in the isradipine group and two patients in the placebo group. None of the patients experienced ischemic complications during the study.(ABSTRACT TRUNCATED AT 400 WORDS)

Case report: radiological appearances in peliosis hepatis

Peliosis hepatis is an unusual disorder characterized by blood filled hepatic spaces. We describe the appearances of this entity on ultrasonography, computed tomography and magnetic resonance imaging. The importance of peliosis hepatis is that it may be an indicator of a treatable underlying condition.

Enalapril in the treatment of congestive heart failure

Congestive heart failure (CHF) is a complex clinical syndrome affecting 1% of the U.S. population. The basic dysfunction, a lack of sufficient blood flow to the periphery, triggers reflex neurohumoral mechanisms that cause systemic vasoconstriction and sodium and water retention as the body attempts to protect vital organs. This, in turn, results in additional work for the failing heart and further deterioration. Vasodilators, in general, and angiotensin converting enzyme (ACE) inhibitors, in particular, interrupt this pathophysiology and improve hemodynamics. Enalapril, a long-acting ACE inhibitor, has been demonstrated to improve New York Heart Association (NYHA) functional class, pulmonary capillary wedge pressure, cardiac index, maximum oxygen uptake, and exercise tolerance in CHF patients. Data from a recent trial provide evidence that a group of patients with severe CHF who were treated with enalapril showed reduced heart size, reduced need for other heart-failure medication, and reduced mortality.

Sustained high-dose nitroglycerin transcutaneous patch therapy in angina pectoris: evidence for attenuation of effect over time

The safety and efficacy of using continuous high-dose transcutaneous nitroglycerin in doses up to 100 mg/24 hours in chronic stable angina was assessed in 20 patients using serial treadmill testing. Patients had first to show a response to sublingual nitroglycerin with a 20% improvement in exercise time. All patients were then titrated with 20 mg (40 cm2), 60 mg (120 cm2), 80 mg (160 cm2) or 100 mg (200 cm2) patches, until intolerable headache in association with a 10 mmHg reduction in blood pressure and a ten-beat increment in heart rate. Drug was then discontinued for 2 days and patients underwent three repeat stress tests to reestablish a consistent drug-free baseline. Patients were then randomized in double-blind fashion to receive either active patch (N = 11) in previous titration dose or placebo patch (N = 9), with treadmill tests performed at 0 (1 hour after previous patch removal), 4, and 24 hours after patch application at baseline and at weeks 1 and 2. Venous blood was obtained for measurement of plasma nitroglycerin levels. After the first 24 hours of active patch therapy, there was a significant reduction in systolic blood pressure (P = .05), a significant increase in heart rate (P = .01), and a minor increase in exercise tolerance (P = .06) compared to placebo. At weeks 1 and 2, there was an attenuation of drug effect in all of these parameters. Plasma nitroglycerin levels demonstrated consistently high plasma levels over each 24-hour dosing interval, on day 1, week 1, and week 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of nicardipine as monotherapy for chronic, stable angina

Using a double-blind, Latin square protocol designed to detect dose response, nicardipine hydrochloride, a new calcium antagonist, was studied as monotherapy for stable exertional angina. Eighty-one patients were enrolled in the trial and 62 patients were included in greater than or equal to 1 primary efficacy analyses. Patients received 1 to 2 weeks of placebo run-in, then 5 weeks of treatment with placebo and with 10, 20 and 30 mg of nicardipine given 3 times daily. Patients completed symptom diaries, were monitored with 24-hour electrocardiographic Holter monitors and underwent serial exercise treadmill tests. By 1 hour, 10, 20 and 30 mg of nicardipine administered 3 times daily produced statistically significant, dose-related improvements in all key exercise parameters, which persisted at the 4-hour evaluation. The systolic blood pressure at rest and during exercise decreased, but the pulse slightly increased. The peak rate-pressure product was unchanged. The side effects were not severe. Nicardipine hydrochloride is an effective, well-tolerated medication for the treatment of stable exertional angina, and is a good alternative to currently available calcium antagonists.

Quaternary opiate antagonists lower blood pressure and inhibit leucine-enkephalin responses

The quaternary opiate antagonists naloxone methylbromide (MB) and naltrexone MB do not cross the blood-brain barrier, and may be used to differentiate peripheral from central nervous system effects of the opioid peptides. When administered intravenously to the conscious, chronically instrumented dog, naloxone MB transiently reduces mean systemic arterial pressure and increases heart rate in a dose-dependent manner over the concentration range from 0.1 to 1.0 mg/kg. The [Leu5]enkephalin response is completely inhibited at naloxone MB doses as low as 0.25 mg/kg, but this inhibition has terminated by 30 min after dosing. Naltrexone MB displays a similar spectrum of activity. This inhibition of the intravenous [Leu5]enkephalin response by the quaternary opiate antagonists indicates that the [Leu5]enkephalin response occurs by activation of peripheral receptor sites. The decrease in mean pressure induced by these antagonists coupled with the inhibition of the [Leu5]enkephalin response suggests that peripheral enkephalins may play a role in blood pressure regulation.

Extrarenal contributions to indapamide's antihypertensive mechanism of action

Autonomic responses in heart rate and blood pressure to Valsalva maneuvers and changes in vascular reactivity to pressor doses of phenylephrine and angiotensin II were studied before and after treatment with indapamide, a new antihypertensive diuretic. Six healthy male volunteers, placed on a daily diet consisting of 100 mEq of sodium, 80 mEq of potassium, and a fluid intake of 2500 ml, participated in this single-blind, placebo-controlled study. During active treatment, 5 mg of indapamide was administered once daily for 14 days. On the mornings of hemodynamic testing, samples of blood, 24-hour urine, and plasma were obtained and analyzed for hematocrit, catecholamines and their metabolites, plasma renin activity, and aldosterone levels. Since each subject served as his own control, the results were analyzed by the paired t-test method. Plasma renin activity and 24-hour urinary aldosterone levels increased (p less than 0.05), and serum potassium and chloride levels decreased (p less than 0.05). No other significant laboratory changes were noted after treatment, including changes in the plasma and urinary catecholamine levels. Following treatment, responses in heart rate and blood pressure to Valsalva maneuvers were unaltered. During the control period the doses of phenylephrine and angiotensin II required to raise the systolic pressure 25 to 35 mm Hg and the diastolic pressure 20 to 30 mm Hg were 5.03 +/- 0.72 micrograms/kg and 16.7 +/- 2.1 ng/kg, respectively. After treatment, the doses of phenylephrine and angiotensin II were significantly (p less than 0.05) greater: 10.72 +/- 1.02 micrograms/kg and 31.7 +/- 4.8 ng/kg, respectively. Dose-response relationships to these pressor agents were shifted in parallel to the right after treatment. A small but significant decrease in body weight, which may have reflected a decrease in plasma volume, was observed. However, no orthostatic changes between the supine and erect mean arterial blood pressures or incremental increases in heart rates were noted between the two periods. An increase in hematocrit and blunting of the diastolic overshoot during the Valsalva maneuvers that were used as indexes of plasma volume contraction were also not observed. In summary, our results indicate that changes in vascular responsiveness occurred by mechanisms independent of changes in the autonomic nervous system, since plasma norepinephrine levels did not change and responsiveness to Valsalva maneuvers was unaltered. Furthermore, it appears that this effect on the vasculature was probably not related to changes in plasma volume.

Leucine-enkephalin: reversal of intrinsic cardiovascular stimulation by pentobarbital

In the conscious, chronically instrumented dog, leucine-enkephalin ([Leu5]ENK), 35 micrograms/kg injected intravenously, increased heart rate, respiratory rate, systolic and diastolic systemic arterial pressures, mean pulmonary arterial pressure, and cardiac output. After pentobarbital-induced anesthesia, the same dose of [Leu5]ENK decreased heart rate, systemic and pulmonary arterial pressures, and cardiac output. Responses both before and after pentobarbital were blocked by naloxone. These results indicate that barbiturate anesthesia can reverse the cardiovascular stimulatory activity of intravenously administered [Leu5]ENK.