Deep Learning in Biomedical Optics

This article reviews deep learning applications in biomedical optics with a particular emphasis on image formation. The review is organized by imaging domains within biomedical optics and includes microscopy, fluorescence lifetime imaging, in vivo microscopy, widefield endoscopy, optical coherence tomography, photoacoustic imaging, diffuse tomography, and functional optical brain imaging. For each of these domains, we summarize how deep learning has been applied and highlight methods by which deep learning can enable new capabilities for optics in medicine. Challenges and opportunities to improve translation and adoption of deep learning in biomedical optics are also summarized. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

High compression deep learning based single-pixel hyperspectral macroscopic fluorescence lifetime imaging in vivo

Single pixel imaging frameworks facilitate the acquisition of high-dimensional optical data in biological applications with photon starved conditions. However, they are still limited to slow acquisition times and low pixel resolution. Herein, we propose a convolutional neural network for fluorescence lifetime imaging with compressed sensing at high compression (NetFLICS-CR), which enables in vivo applications at enhanced resolution, acquisition and processing speeds, without the need for experimental training datasets. NetFLICS-CR produces intensity and lifetime reconstructions at 128 × 128 pixel resolution over 16 spectral channels while using only up to 1% of the required measurements, therefore reducing acquisition times from ∼2.5 hours at 50% compression to ∼3 minutes at 99% compression. Its potential is demonstrated in silico, in vitro and for mice in vivo through the monitoring of receptor-ligand interactions in liver and bladder and further imaging of intracellular delivery of the clinical drug Trastuzumab to HER2-positive breast tumor xenografts. The data acquisition time and resolution improvement through NetFLICS-CR, facilitate the translation of single pixel macroscopic flurorescence lifetime imaging (SP-MFLI) for in vivo monitoring of lifetime properties and drug uptake.

d-serine regulation of the timing and architecture of the inspiratory burst in neonatal mice

d-serine, released from mouse medullary astrocytes in response to increased CO₂ levels, boosts the respiratory frequency to adapt breathing to physiological demands. We analyzed in mouse neonates, the influence of d-serine upon inspiratory/expiratory durations and the architecture of the inspiratory burst, assessed by pwelch's power spectrum density (PSD) and continuous wavelet transform (CWT) analyses. Suction electrode recordings were performed in slices from the ventral respiratory column (VRC), site of generation of the respiratory rhythm, and in brainstem-spinal cord (en bloc) preparations, from the C5 ventral roots, containing phrenic fibers that in vivo innervate and drive the diaphragm, the main inspiratory muscle. In en bloc and slice preparations, d-serine (100 μM) reduced the expiratory, but not the inspiratory duration, and increased the frequency and the regularity of the respiratory rhythm. In en bloc preparations, d-serine (100 μM) also increased slightly the amplitude of the integrated inspiratory burst and the area under the curve of the integrated inspiratory burst, suggesting a change in the recruitment or the firing pattern of neurons within the burst. Time-frequency analyses revealed that d-serine changed the burst architecture of phrenic roots, widening their frequency spectrum and shifting the position of the core of firing frequencies towards the onset of the inspiratory burst. At the VRC, no clear d-serine induced changes in the frequency-time domain could be established. Our results show that d-serine not only regulates the timing of the respiratory cycle, but also the recruitment strategy of phrenic motoneurons within the inspiratory burst.

Assessing patterns for compressive fluorescence lifetime imaging

A novel hyperspectral single pixel system was used to compare different compressive basis patterns for intensity imaging, lifetime imaging, and FRET quantification. Six popular basis patterns were compared experimentally in a phantom containing two fluorescent dyes. The basis patterns that performed best for lifetime quantification were used to measure FRET occurrence in well-plate samples with varying acceptor-donor ratios. The ABS-WP approach using Haar patterns and the compressive sensing approach with Hadamard Ranked patterns displayed the best overall performances at a 50% compression ratio.

Effect of the drying conditions on the microstructure of silica based xerogels and aerogels

Nanostructured silica based xerogels and aerogels are prepared by sol-gel technology, using methyltrimethoxysilane as precursor. The influence of the drying method and conditions on the microstructure of the obtained materials is investigated, since the drying stage has a critical influence on their porosity. Two types of drying methods were used: atmospheric pressure drying (evaporative), to produce xerogels, and supercritical fluids drying, to obtain aerogels. Although the supercritical fluids drying technique is more expensive and hazardous than the atmospheric pressure drying, it is well known that aerogels are less dense than the xerogels due to less pore shrinkage. However, the ideal situation would be to use atmospheric pressure drying in conditions that minimize the pore collapse. Therefore, in this work, different temperature cycles for atmospheric pressure drying and two heating rates for the supercritical fluids drying are tested to study the gels' shrinkage by analyzing the density and porosity properties of the final materials. The best materials obtained are aerogels dried with the lower heating rate (approximately 80 degrees C/h), since they exhibit very low bulk density (approximately 50 kg/m3), high porosity (95%)-mainly micro and mesopores, high surface area (approximately 500 m2/g), moderate flexibility and a remarkable hydrophobic character (>140 degrees). It was proved that the temperature cycles of atmospheric pressure drying can be tuned to obtain xerogels with properties comparable to those of aerogels, having a bulk density only approximately15 kg/m3 higher. All the synthesized materials fulfill the requirements for application as insulators in Space environments.

Primary hepatic actinomycosis presenting as purulent pericarditis with cardiac tamponade

Cardiac tamponade constitutes an exceptional form of actinomycosis. We describe a case of primary hepatic actinomycosis presenting as purulent pericarditis with cardiac tamponade in a 20-year-old patient with previous esophagectomy and colonic interposition, successfully managed by computed tomography-guided percutaneous drainage and a prolonged course of antibiotic treatment. Actinomyces israelii was identified in the pericardial fluid by 16S rRNA gene sequencing. The literature on the simultaneous presentation of cardiac and hepatic actinomycosis is reviewed.

[Treatment of hydrocephalus secondary to intraventricular haemorrhage in preterm infants. A review of the literature]

INTRODUCTION

The current incidence of intraventricular haemorrhage in low-weight preterm infants is 20%. The percentage of patients who are going to develop hydrocephalus secondary to this haemorrhage varies greatly. In the last 20 years different medical and surgical treatments have been put forward to prevent both the occurrence of haemorrhage and the development of hydrocephalus.

DEVELOPMENT

In this study we review the literature on the different treatments used to control and treat hydrocephalus. From the medical point of view, treatment with pharmacological agents such as azetazolamide or furosemide offers more drawbacks than advantages as far as their capacity to prevent hydrocephalus is concerned. Treatments involving fibrinolytic agents offer a high risk of triggering new haemorrhages but in recent years their use has been taken up again in combination with ventricular drains. As regards surgical treatment of hydrocephalus due to haemorrhage, despite the risk of infection, it is more advisable to use ventricular drains than to introduce subgaleal reservoirs. At the present time, the best definitive treatment for hydrocephalus in preterm infants is still the ventriculoperitoneal shunt. The most suitable time is when the weight of the newborn infant exceeds 1500 g and the cerebrospinal fluid offers a protein count above 200 mg/dL.

CONCLUSIONS

The long-term neurological development of these children depends mainly on the severity of the haemorrhage, but poorer prognoses are observed in cases in which complications arise from the control examinations of the valve shunt systems.

Surgical treatment of symptomatic cavernous malformations of the brainstem

INTRODUCTION AND OBJECTIVES

Cavernous malformations (CM) at the level of the brainstem, continue to present a challenge in therapeutic terms and are an important source of controversy. Here we present our experience and the results obtained by adopting surgical treatment.

MATERIALS AND METHODS

The results of a consecutive series of 17 patients were studied. The surgical intervention was designed after: 1. A neurological examination. 2. MRI and cerebral angiography. 3. Correlation with anatomical brainstem maps. The surgical intervention was approached from the most damaged zone or through a zone which was functionally least important.

RESULTS

Complete extirpation was achieved in 15 patients without mortality. In a few patients the surgical intervention temporarily aggravated the prior lesion of the cranial nerves (2/17) or damage new sensory tracts (2/17). The functional post-operative recovery was good, in terms of consciousness (4/5), cranial nerves (11/17), the pyramidal tract (3/5) and the cerebellum (2/4). Of the patients that were operated, 14 of 17 returned to their professional activities.

CONCLUSIONS

The results of surgery can surpass the morbidity-mortality of the natural history or treatment with radiosurgery. There is a clear consensus in recommending surgical intervention for CMs that are superficially located, in young patients and in those with a risk of further bleeding. It is probably best that the surgery is performed during the subacute period, when the MRI offers a clear image confirming the presence of the CM.

Plasma nitrate accumulation during the development of pacing-induced dilated cardiac myopathy in conscious dogs is due to renal impairment

Heart failure is associated with an increase in plasma nitrate and nitrite (NOx). To date there is still some controversy regarding the causes of nitrate accumulation during the development of heart failure. The goal of this study was to analyze the underlying mechanisms that cause accumulation of plasma nitrates during the development of heart failure in dogs. Dogs were chronically instrumented for measurement of hemodynamics and renal function. Hearts were paced initially at 210 bpm for 3 weeks and then at 240 until the development of heart failure. Hemodynamics, renal function, renal blood flow, arterial blood gases, hemoglobin, plasma and urine NOx levels, and creatinine levels were measured weekly. Heart failure was assessed by hemodynamic alterations, physical signs such as lethargy, ascites, cachexia, and postmortem evidence of cardiac hypertrophy. LVSP (from 127 +/- 3 to 106 +/- 3 mmHg), LV dP/dt (from 2658 +/- 173 to 1439 +/- 217 mmHg/s), MAP (from 101 +/- 1.9 to 83 +/- 1.8 mmHg) fell, whereas LVEDP tripled (from 6.4 +/- 0.9 to 20 +/- 2.6 mmHg), and heart rate rose (from 101 +/- 4.2 to 117 +/- 6.3 bpm), all changes P < 0.05. RBF (from 146 +/- 10 to 96 +/- 9.9 ml/min), urine output (V) (from 0.26 +/- 0.02 to 0.16 +/- 0.02 ml/min), GFR (from 63 +/- 1.8 to 49 +/- 2 ml/min), and Na excretion (from 45 +/- 4.5 to 14 +/- 4.6 microEq/min) all decreased (P < 0.05), whereas RVR increased (from 0.68 +/- 0.05 to 0.94 +/- 0.1 mmHg/ml/min). These changes took place during a rise in plasma NOx (from 3.7 +/- 0.5 to 16+/-3.3 microM), a decrease in urine NOx (from 33 +/- 9.9 to 8.1 +/- 4.9 microM), and a concurrent increase in NOx reabsorption (from 221 +/- 31 to 818 +/- 166 nmol/min). There was a direct correlation between the increase in plasma NOx levels and an increase in filtered load (r(2) = 0.97, P = 0.02), a negative correlation between NOx levels and NOx excretion (r(2) = 0.65 P < 0.09), and a direct correlation between plasma NOx levels and NOx reabsorption (r(2) = 0.97, P = 0.02). These results indicate that elevated plasma NOx during heart failure are most likely the result of an impairment of the renal function and not increased NOx production. Furthermore, without knowing changes in renal function the measurement of plasma NOx in and of itself is a meaningless index of NO formation.

Endogenous nitric oxide in the control of skeletal muscle oxygen extraction during exercise

Our previous studies uncovered an inhibitory effect of nitric oxide (NO) on leg skeletal muscle respiration in dogs at rest. The role of NO in the modulation of O2 consumption and O2 extraction in hindlimb muscle during elevated metabolic states was investigated in chronically instrumented dogs while walking and at three exercise intensities which markedly increased hindlimb blood flow. Walking resulted in increased O2 consumption by 17 +/- 4 mL min-1 and O2 extraction from 24 +/- 1 to 37 +/- 8%, with no alteration in hindlimb blood flow (BFLeg) and vascular resistance (VRLeg). Running at the highest speed (9.1 mph) resulted in an increase in BFLeg from 0.67 +/- 0.05 to 2.2 +/- 0.1 L min-1, a reduction of VRLeg and elevation of hindlimb O2 consumption from 33 +/- 3 to 226 +/- 21 mL min-1 and O2 extraction from 29 +/- 2 to 61 +/- 5%, with a decrease in leg venous PO2 from 38 +/- 1 to 25 +/- 1 mmHg. After nitro-L-arginine (NLA) (35 mg kg-1, i.v.) to inhibit endogenous NO synthesis, walking caused greater increases in hindlimb O2 consumption (29 +/- 5 mL min-1) and O2 extraction (43 +/- 1 to 60 +/- 3%) (both P < 0.05), with no significant change in BFLeg. During running at the highest speed, BFLeg was 1.9 +/- 0.1 L min-1 (P < 0. 05) and VRLeg was higher, accompanied by increases in hindlimb O2 consumption from 49 +/- 7 to 318 +/- 24 mL min-1 and O2 extraction from 41 +/- 2 to 79 +/- 4% (both P < 0.05), with a greater decrease in leg venous PO2 from 33 +/- 1 to 20 +/- 1 mmHg (P < 0.05). Similar results were found for intermediate levels of exercise. Our results indicate that NO modulates hindlimb skeletal muscle O2 extraction and O2 usage whether blood flow increased or not during exercise.

Myocardial glucose uptake is regulated by nitric oxide via endothelial nitric oxide synthase in Langendorff mouse heart

Although the role of nitric oxide (NO) in the modulation of vascular tone has been studied and well understood, its potential role in the control of myocardial metabolism is only recently evident. Several lines of evidence indicate that NO regulates myocardial glucose metabolism; however, the details and mechanisms responsible are still unknown. The aim of this study was to further define the role of NO in the control of myocardial glucose metabolism and the nitric oxide synthase (NOS) isoform responsible using transgenic animals lacking endothelial NOS (ecNOS). In the present study, we examined the regulation of myocardial glucose uptake using isometrically contracting Langendorff-perfused hearts from normal mice (C57BL/6J), mice with defects in the expression of ecNOS [ecNOS (-/-)], and its heterozygote [ecNOS (+/-)], and wild-type mice [ecNOS (+/+)] (n=6, respectively). In hearts from normal mice, little myocardial glucose uptake was observed. This myocardial glucose uptake increased significantly in the presence of N(omega)-nitro-L-arginine methyl ester (L-NAME). Similarly, in the hearts from ecNOS (-/-), glucose uptake was much greater than in normal mice, whereas myocardial glucose uptake of ecNOS (+/-) and ecNOS (+/+) mice was not different from normal mice. In addition, myocardial glucose uptake of ecNOS (+/-) and ecNOS (+/+) mice increased significantly in the presence of L-NAME. At a workload of 800 g. beats/min, L-NAME increased glucose uptake from 0.1+/-0.1 to 3+/-0.4 microg/min x mg in ecNOS (+/-) mice and from 0.2+/-0.1 to 2.7+/-0.7 microg/min x mg in ecNOS (+/+) mice. Furthermore, in the hearts from ecNOS (-/-) mice, 8-bromoguanosine 3':5'-cyclic monophosphate (8-Br-cGMP), a cGMP analog or S-nitroso-N-acetylpenicillamine (SNAP), a NO donor essentially shut off glucose uptake, and in hearts from ecNOS (+/-) mice, 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ), an inhibitor of cGMP, increased the glucose uptake significantly. These results indicate clearly that cardiac NO production regulates myocardial glucose uptake via a cGMP-dependent mechanism and strongly suggest that ecNOS plays a pivotal role in this regulation. These findings may be important in the understanding of the pathogenesis of the diseases such as ischemic heart disease, heart failure, diabetes mellitus, hypertension, and hypercholesterolemia, in which NO synthesis is altered and substrate utilization by the heart changes.

Bovine polymerized hemoglobin increases cardiac oxygen consumption and alters myocardial substrate metabolism in conscious dogs: role of nitric oxide

We investigated the effect of bovine polymerized hemoglobin-based oxygen carrying (HBOC) solution on myocardial oxygen consumption (MVO2) and substrate use. At 15 min after the end of HBOC infusion (20% blood volume, i.v.) in nine permanently instrumented conscious dogs, mean arterial pressure and coronary blood flow were both increased by 41+/-5% and 93+/-20% (p<0.01) without affecting late diastolic coronary resistance and left ventricular dP/dtmax. Administration of HBOC did not affect arterial PO2 or O2 content, but significantly decreased coronary sinus PO2 and O2 content by 21+/-3% and 36+/-3%, respectively. MVO2 was increased from 7.2+/-0.8 to 15+/-1.8 ml O2/min (p<0.01). Despite an increase in triple product from 44+/-2 to 56+/-3 (p<0.01) 15 min after HBOC, the ratio of MVO2 and triple product was markedly elevated by 62+/-19%. Myocardial free fatty acid consumption was decreased from 14+/-1 to 4.5+/-2.2 microEq/min, whereas consumption of lactate increased from 19+/-6 to 69+/-10 micromol/ min and that of glucose increased from 1.0+/-0.5 to 10+/-3 mg/min (all p values, <0.05). These metabolic changes were not observed in dogs that received angiotensin II at a dose used (20-40 ng/kg/min, i.v.) to match those hemodynamic effects of HBOC. These results suggest that administration of HBOC increases coronary blood flow and MVO2 and shifts cardiac metabolism from using free fatty acid to using lactate and glucose in conscious dogs at rest. These metabolic changes are independent of the HBOC-induced change in hemodynamics.

Nitric oxide controls cardiac substrate utilization in the conscious dog

OBJECTIVES

The aim of this study was to determine whether the acute inhibition of nitric oxide (NO) synthase causes changes in cardiac substrate utilization which can be reversed by a NO donor.

METHODS

NO synthase was blocked by giving 30 mg/kg of nitro-L-arginine (NLA) i.v. to 15 chronically instrumented dogs. Hemodynamics and blood samples from aorta and coronary sinus were taken at control and at 1 and 2 h after NLA. In five dogs, 0.4 mg/kg of the NO donor 3754 was given i.v. 1 h after NLA. In six dogs, angiotensin II was infused over 2 h (20-40 ng/kg/min) to mimic the hemodynamic effects of NLA.

RESULTS

Two h after NLA: mean arterial pressure was 153 +/- 4 mmHg; MVO2 increased by 38%; cardiac uptake of lactate and glucose increased, respectively, from 20.0 +/- 5.0 to 41.0 +/- 9.3 mumol/min and from 1.1 +/- 0.7 to 6.8 +/- 1.5 mg/min (all P < 0.05 vs. control). Cardiac uptake of free fatty acids decreased by 43% after 1 h (P < 0.05) and returned to control values at 2 h. Cardiac respiratory quotient increased from 0.76 +/- 0.03 to 1.05 +/- 0.07, indicating a shift to carbohydrate oxidation. All these changes were reversed by the NO donor. In the dogs receiving angiotensin II infusion, MVO2 increased by 28% and lactate uptake doubled (both P < 0.05), but no other metabolic changes where observed.

CONCLUSIONS

The acute inhibition of NO synthase by NLA causes a switch from fatty acids to lactate and glucose utilization by the heart which can be reversed by a NO donor, suggesting an important regulatory action of NO on cardiac metabolism.

Reduced coronary NO production in conscious dogs after the development of alloxan-induced diabetes

The role of nitric oxide (NO) in the control of coronary blood flow (CBF) during the development of diabetes is unknown. To study this, mongrel dogs were chronically instrumented using sterile techniques for measurements of systemic hemodynamics and CBF. With heart rate controlled (150 beats/min), veratrine (1-10 micrograms/kg) caused dose-dependent increases in CBF; e.g., 5 mirograms/kg of veratrine increased CBF by 57 +/- 7% from 41 +/- 1.3 ml/min (P < 0.05). The dogs developed diabetes 4-5 wk after injection of alloxan (40-60 mg/kg iv, blood glucose levels were 384 +/- 18 mg/dl). After diabetes the same doses of veratrine caused smaller increases in CBF; i.e., 5 micrograms/kg of veratrine increased CBF by 32 +/- 2% (P < 0.05 compared with control) from 28 +/- 4 ml/min. ACh- and adenosine-induced coronary vasodilation were reduced after diabetes as well. In anesthetized dogs after diabetes, vagal stimulation caused smaller increases in CBF. ACh and bradykinin caused smaller increases in NO(-)(2) production in coronary microvessels from diabetic dogs. Furthermore, despite the fact that mRNA for endothelial cell NO synthase from the aorta was increased twofold with the use of Northern blotting, the protein for aortic endothelial constitutive NO synthase was reduced by 66% after diabetes, as determined by Western blotting. Our results indicate that the NO-dependent coronary vasodilation by the Bezold-Jarisch reflex is impaired in conscious dogs after diabetes. The mechanism responsible for the impaired endothelium-dependent coronary vasodilation is most likely the decreased release of NO from the endothelium.

Role of nitric oxide in the control of renal oxygen consumption and the regulation of chemical work in the kidney

Inhibition of NO synthesis has recently been shown to increase oxygen extraction in vivo, and NO has been proposed to play a significant role in the regulation of oxygen consumption by both skeletal and cardiac muscle in vivo and in vitro. It was our aim to determine whether NO also has such a role in the kidney, a tissue with a relatively low basal oxygen extraction. In chronically instrumented conscious dogs, administration of an inhibitor of NO synthase, nitro-L-arginine (NLA, 30 mg/kg i.v.), caused a maintained increase in mean arterial pressure and renal vascular resistance and a decrease in heart rate (all P<0.05). At 60 minutes, urine flow rate and glomerular flow rate decreased by 44+/-12% and 45+/-7%, respectively; moreover, the amount of sodium reabsorbed fell from 16+/-1.7 to 8.5+/-1.1 mmol/min (all P<0.05). At this time, oxygen uptake and extraction increased markedly by 115+/-37% and 102+/-34%, respectively (P<0.05). Oxygen consumption also significantly increased from 4.5+/-0.6 to 7.1+/-0.9 mL O2/min. Most important, the ratio of oxygen consumption to sodium reabsorbed increased dramatically from 0.33+/-0.07 to 0.75+/-0.11 mL O2/mmol Na+ (P<0.05), suggesting a reduction in renal efficiency for transporting sodium. In vitro, both a NO-donating agent and the NO synthase-stimulating agonist bradykinin significantly decreased both cortical and medullary renal oxygen consumption. In conclusion, NO plays a role in maintaining a balance between oxygen consumption and sodium reabsorption, the major ATP-consuming process in the kidney, in conscious dogs, and NO can inhibit mitochondrial oxygen consumption in canine renal slices in vitro.

Exercise reduces epicardial coronary artery wall stiffness: roles of cGMP and cAMP

OBJECTIVE

Exercise enhances the dilation of the epicardial coronary arteries by vasodilator drugs and blood flow. Our goal was to determine whether coronary artery elastic properties were affected by brief exercise training.

METHODS

Arterial pressure and left circumflex coronary artery diameter were measured in dogs. Venous bolus injections of acetylcholine 5 microg x kg(-1) (ACH) and nitroglycerin 25 microg x kg(-1) (NTG) or infusions of adenosine 0.5 microM/kg/min (ADO) were given. Fifteen-second coronary artery occlusions were performed. Dogs exercised 2 h x d(-1) for 7 d at 10.9 km x h(-1). Experiments were repeated. Pressure and coronary radius data were used to calculate vessel wall stress and incremental wall modulus, Einc.

RESULTS

Baseline Einc and radius were not changed by exercise. Before exercise Einc increased similarly from baseline for all vasodilators. After exercise, the increase in Einc with ADO was unchanged. However, the increase was attenuated during ACH, abolished with occlusion, and reversed with NTG despite enhanced dilation.

CONCLUSION

Data suggest that functional remodeling of epicardial arteries begins soon after starting exercise training, before changes in resting vessel diameter, is mediated by cGMP, and contributes to increased vascular dilation. Brief exercise training enhances the vasodilating capability and elastic properties of large coronary arteries.

Relationship between plasma NOx and cardiac and vascular dysfunction after LPS injection in anesthetized dogs

The relationship between plasma nitrite, nitrate, and nitric oxide (NOx), cytokines, and cardiac and vascular dysfunction after lipopolysaccharide (LPS) was studied in chronically instrumented anesthetized dogs. LPS was administered (1 mg/kg i.v.), and hemodynamics were recorded at baseline, every 15 min for 1 h, and every hour for an additional 14 h. Dramatic reductions in mean arterial pressure (-48 +/- 6%), cardiac output (-40 +/- 8%), stroke volume (-42 +/- 9%), and first derivative of left ventricular pressure (LV dP/dt, -38 +/- 7%) were seen within 1 h after injection of endotoxin. Cardiac output was not different from control by 9 h, whereas mean arterial pressure (-19 +/- 7%), stroke volume (-32 +/- 8%), and LV dP/dt (-21 +/- 10%) remained significantly depressed from control. Total peripheral resistance was not significantly different from control. Therefore, the hypotension appears to be due to a reduction in cardiac function and not to vasodilation. Levels of plasma NOx were not different from control until 4 h after LPS reached levels 597 +/- 126% higher than control at 15 h. In vitro production of nitrite by coronary microvessels was also elevated, supporting our in vivo findings. In contrast, production of tumor necrosis factor-alpha and interleukin-6 occurred shortly after endotoxin injection, reaching peak levels at 45 and 150 min, respectively. Our data suggest that inducible nitric oxide synthase induction occurred after LPS injection. It is unlikely that nitric oxide contributed significantly to the hypotension and cardiac dysfunction early in our study, whereas cardiodepressive cytokines, particularly tumor necrosis factor-alpha, may be important. In contrast, the hemodynamic effects seen late after injection of endotoxin may be the result of an overproduction of nitric oxide, since there was a sixfold increase in plasma NOx levels at this time and a marked production of nitric oxide in isolated coronary microvessels in vitro.

Mechanisms of nitrate accumulation in plasma during pacing-induced heart failure in conscious dogs

The goal of this study was to understand the mechanisms behind the changes in plasma NOx during heart failure. Heart failure is associated with an increase in plasma nitrate levels, and yet most experimental evidence demonstrates a reduction in endothelial nitric oxide production during heart failure. Dogs were chronically instrumented for measurement of systemic hemodynamics and left ventricular (LV) dimensions. Hearts were paced at 210 bpm for 3 weeks (n = 14) and then 240 bpm for 1 week (n = 7). Hemodynamics, arterial blood gases, plasma NOx, and creatinine levels were monitored weekly. Heart failure was evidenced by cachexia, ascites, and hemodynamic alterations. Resting heart rate rose (94 +/- 6 to 135 +/- 9 bpm), and LV dP/dt fell (2810 +/- 82 to 1471 +/- 99 mm Hg/s), while LV end diastolic pressure quadrupled (5.8 +/- 0.7 to 25 +/- 0.8 mm Hg), and diastolic wall stress quadrupled (11 +/- 1.3 to 43 +/- 6.0 g/cm2, all P < 0.05). These changes occurred during a doubling in plasma NOx (5.5 +/- 1.5 to 10 +/- 1.6 microM, P < 0.05). There were no changes in plasma NOx through 3 weeks of pacing. Plasma creatinine levels increased 450% (from 0.27 +/- 0.32 to 1.21 +/- 0.63 mg%). Stimulated nitrite production by agonists in sieved coronary microvessels was unchanged after 3 weeks of pacing but was reduced after heart failure. Plasma NOx did not correlate with LV dP/dt or systolic wall stress but correlated directly with LV EDP or diastolic wall stress and inversely with cardiac work. Plasma NOx rose in direct relation to plasma creatinine levels (Y = 4.8X + 2.8, r2 = 0.84), suggesting that the rise in plasma NOx during heart failure is due to decreased renal function not increased NO production.

Short-term exercise training enhances reflex cholinergic nitric oxide-dependent coronary vasodilation in conscious dogs

The effects of exercise training on the coronary vasodilation following activation of the Bezold-Jarisch reflex were examined in conscious dogs. Mongrel dogs were chronically instrumented using sterile techniques for measurements of systemic hemodynamics and left circumflex coronary blood flow (CBF). With the heart rate controlled (150 bpm), veratrine (0.5 to 20 micrograms/kg) caused dose-dependent increases in CBF; eg, 5 micrograms/kg of veratrine increased CBF by 61 +/- 6% from 31 +/- 1.3 mL/min (P < .05). After exercise training, the dose-response curve of CBF in response to veratrine was shifted to the left; eg, 5 micrograms/kg of veratrine increased CBF by 101 +/- 12% (P < .05 compared with control) from 34 +/- 2.3 mL/min. The enhanced coronary vasodilation was blunted by nitro-L-arginine (NLA, 35 mg/kg). In anesthetized dogs after exercise training, electrical stimulation of the left vagus nerve caused greater increases in CBF, and NLA inhibited increases in CBF. Acetylcholine, norepinephrine, angiotensin II, and bradykinin caused greater increases in NO2- production in coronary microvessels from exercise-trained dogs compared with those from normal dogs. Our results indicate that the coronary vasodilation following activation of the Bezold-Jarisch reflex is enhanced in conscious dogs after exercise training. Since electrical stimulation of the vagus nerve caused greater coronary vasodilation and since the agonists resulted in greater increases in NO production in coronary microvessels from exercise-trained dogs, the mechanism responsible for the enhanced coronary vasodilation following activation of the Bezold-Jarisch reflex is most likely due to the increased release of NO from the endothelial cells.

Interaction between prostacyclin and nitric oxide in the reflex control of the coronary circulation in conscious dogs

OBJECTIVE

Our goal was to determine the role of nitric oxide (NO) on the coronary vasodilation induced by prostacyclin (PGI2) in conscious dogs.

METHODS

Dogs were chronically instrumented for the measurements of coronary blood flow (CBF), left ventricular pressure (LVP), mean arterial pressure (MAP) and heart rate (HR).

RESULTS

Intravenous injections of PGI2 caused dose-dependent increases in CBF, and decreases in MAP and late diastolic coronary resistance (LDCR). For instance, CBF increased by 128 +/- 19% (P < 0.05) from 30 +/- 3.5 ml/min and LDCR decreased by 73 +/- 3% (P < 0.05) from 2.57 +/- 0.20 mmHg/ml/min following injection of PGI2 (1.0 microgram/kg). After infusion of nitro-L-arginine (NLA, 35 mg/kg) intravenously, the coronary vasodilation induced by PGI2 was partially attenuated. PGI2 (1.0 microgram/kg) increased CBF by 55 +/- 15% from 33 +/- 5.3 ml/min and decreased LDCR by 42 +/- 9% (both P < 0.05, compared with before NLA) from 3.29 +/- 0.39 mmHg/ml/min. Infusion of L-arginine (100 mg/kg) reversed the action of NLA. For example, PGI2 (1.0 microgram/kg) increased CBF by 115 +/- 15% from 36 +/- 6 ml/min and decreased LDCR by 68 +/- 3% from 3.02 +/- 0.36 mmHg/ml/min (both P > 0.05, compared with before NLA). Atropine (0.1 mg/kg) partially attenuated the coronary vasodilation induced by PGI2 the magnitude of which was almost identical to that by NLA. NLA or atropine also blunted the coronary vasodilation induced by acetylcholine, while the coronary vasodilation induced by nitroglycerin was not affected by NLA.

CONCLUSION

Our results indicate that the coronary vasodilation induced by PGI2 was partially attenuated by NLA or atropine, suggesting that the coronary vasodilation induced by PGI2 is due to two components: a reflex parasympathetic cholinergic vasodilation mediated by NO and a direct action of PGI2.

Contribution of the ventricles and the atrial appendages to the elevation of plasma atrial natriuretic factor (ANF) during pacing-induced heart failure in conscious dogs

The goal of our study was to determine whether the elevation in plasma ANF was produced by the atrial appendages or ventricular tissue during pacing-induced heart failure in chronically instrumented conscious dogs (sham) or dogs with bilateral atrial appendectomy. Acute volume expansion caused a significant elevation of plasma ANF from 80 +/- 8 to 149 +/- 26 pg/ml (p < 0.01) in sham dogs, but caused no significant change from 67 +/- 7 to 84 +/- 8 pg/ml in atrial appendectomized dogs. There were increases in left ventricular end-diastolic pressure (LVEDP) and left atrial pressure (LAP) in both groups of dogs. After rapid left ventricular pacing (210-240 beats/min) for 4 weeks to induce heart failure, dogs in both groups had tachycardia, elevated LVEDP and higher LAP. Plasma ANF was increased by 250% to 283 +/- 64 pg/ml (p < 0.01) in sham dogs, and only 40% to 94 +/- 15 pg/ml (p > 0.05) in atrial appendectomized dogs. In response to volume expansion, there were further increases in LVEDP and LAP in both groups of dogs, but plasma ANF was not elevated (288 +/- 39 pg/ml) in sham dogs and only slightly increased (132 +/- 7 pg/ml) in atrial appendectomized dogs. Our results suggest that, during pacing-induced heart failure, the atrial appendages are the major source of elevated plasma ANF, and the remaining atrial and ventricular tissue, even when maximally stretched, can only modestly increase plasma ANF.

Epitope mapping of cross-reactive monoclonal antibodies specific for the influenza A virus PA and PB2 polypeptides

Characterization of the epitopes recognized by 21 monoclonal antibodies (MAbs) specific for the influenza A virus PA (13 MAbs) and PB2 (8 MAbs) polypeptides (Bárcena et al. (1994) J. Virol. 68, 6900-6909) raised against denatured polypeptides produced in E. coli is described. MAbs were characterized by: (1) competitive binding ELISAs; (2) mapping of the protein regions that specify their binding sites; and (3) analyses of their ability to recognize the corresponding viral protein in a number of viral isolates. Five and three non-overlapping antigenic areas were defined by the anti-PA and anti-PB2 MAbs, respectively. Five of the anti-PA MAbs recognized antigenic determinants located within the amino-terminal 157 amino acids of the PA protein, and 6 others reacted strongly with a PA fragment comprising the first 236 amino acids. All 8 anti-PB2 antibodies reacted strongly with a polypeptide fragment containing amino acids 1-113 of the PB2 protein. Analyses of the reactivities of 4 anti-P antibodies with 23 influenza A virus reference strains isolated over a period of 61 years and recovered from humans, pigs, birds and horses, showed that the epitopes were conserved among all viral isolates. The application of these antibodies as research and diagnostic tools is discussed.

Selective impairment of vagally mediated, nitric oxide-dependent coronary vasodilation in conscious dogs after pacing-induced heart failure

BACKGROUND

Activation in conscious dogs of the carotid chemoreflex or cardiac receptors results in coronary vasodilation that is mediated by a vagal cholinergic mechanism. Our previous study showed that the coronary vasodilation following activation of carotid chemoreflex is also mediated by nitric oxide (NO). In addition, NO production is depressed after the development of heart failure. Therefore, we hypothesized that the coronary vasodilation after activation of reflexes that elicit efferent vagal coronary vasodilation would be blunted in conscious dogs after pacing-induced heart failure due to the disappearance of NO.

METHODS AND RESULTS

Mongrel dogs were chronically instrumented using sterile techniques for measurements of systemic hemodynamics and left circumflex coronary blood flow (CBF). Without the heart rate controlled, intra-atrial injection of veratrine (4 micrograms/kg) caused bradycardia (-36 +/- 3 beats per minute). With the heart rate controlled, veratrine increased CBF in a dose-dependent manner: for example, 4 micrograms/kg of veratrine increased CBF by 54 +/- 5% from 38 +/- 4.9 mL/min (P < .05). The increases in CBF induced by veratrine were markedly blunted by nitro-L-arginine (NLA). Activation of carotid chemoreflex by nicotine increased CBF by 121 +/- 9% from 32 +/- 4 mL++/min (P < .05) with the heart rate controlled and caused bradycardia (-32 +/- 5 beats per minute) without the heart rate controlled. After the development of heart failure, in response to activation of carotid chemoreflex or cardiac receptors the coronary vasodilation was almost abolished (CBF increased by only 23 +/- 8% or 11 +/- 3%, P < .05 compared with control). There still was a marked bradycardia after injections of nicotine or veratrine (-50 +/- 11 or -48 +/- 7 beats per minute).

CONCLUSIONS

Our results indicate that vagally mediated coronary vasodilation is selectively attenuated in conscious dogs after pacing-induced heart failure, whereas the vagally mediated bradycardia is preserved. Since muscarinic receptor-induced coronary vasodilation is mediated by NO, the disappearance of NO from blood vessels leads to a defect in the integrated neural regulation of coronary blood flow and myocardial function during heart failure.

Role of nitric oxide in the regulation of oxygen consumption in conscious dogs

The role of nitric oxide (NO) in the regulation of O2 consumption was studied in chronically instrumented conscious dogs. A specific NO synthesis inhibitor, nitro-L-arginine (NLA, 30 mg/kg i.v.), significantly increased mean arterial pressure from 100 +/- 4 to 134 +/- 5 mm Hg (mean +/- SEM) and total peripheral resistance by 157 +/- 16% and reduced cardiac output by 47 +/- 3% and heart rate by 34 +/- 6% after 120 minutes. Changes in arterial blood gases were not observed. There were significant changes in PO2 (-14 +/- 2 mm Hg), O2 saturation (-21 +/- 2%), the percentage of hemoglobin as oxyhemoglobin (-21 +/- 2%), and O2 content (-3.0 +/- 0.9 vol%) and a significant increase in percent reduced hemoglobin (21 +/- 1%) in mixed venous blood, associated with an increase in O2 extraction (5.1 +/- 0.2 vol%) (all P < .01). O2 consumption was increased from 124 +/- 6 to 155 +/- 9 mL/min (P < .05). Methoxamine, titrated to have hemodynamic effects similar to those of NLA (eg, mean arterial pressure increased from 97 +/- 4 to 131 +/- 5 mm Hg), had much smaller effects on venous blood gases, hemoglobin, and O2 extraction (2.3 +/- 0.7 vol%) and no significant effect on O2 consumption. NLA also caused an increase in O2 consumption of 37 +/- 8% (P < .01) in quietly resting conscious dogs that had undergone pretreatment with hexamethonium and atropine, but no significant change in O2 consumption in dogs anesthetized with barbiturate.(ABSTRACT TRUNCATED AT 250 WORDS)

Monoclonal antibodies against influenza virus PB2 and NP polypeptides interfere with the initiation step of viral mRNA synthesis in vitro

Two panels of monoclonal antibodies (MAbs) specific for the influenza A virus PA and PB2 polypeptides have been obtained from mice immunized with denatured proteins produced in Escherichia coli. All MAbs (13 specific for the PA polypeptide and 8 specific for the PB2 protein) reacted to the corresponding influenza virus protein in Western blotting (immunoblotting), immunoprecipitation, and immunofluorescence assays. To gain information about the roles of the nucleoprotein (NP) and PB2 and PA proteins during viral mRNA synthesis, the 21 anti-P antibodies and 3 anti-NP antibodies (J. A. López, M. Guillen, A. Sánchez-Fauquier, and J. A. Melero, J. Virol. Methods 13:255-264, 1986) were purified and tested for their ability to inhibit the transcriptase activity associated with viral cores purified from virions. Four of the antibodies (one anti-PB2 and the three anti-NP MAbs) inhibited transcription by more than 50% compared with unrelated control antibodies. The inhibitory effect was not due to a nonspecific effect of the antibody preparations, because these MAbs did not inhibit transcription when tested on influenza B virus nucleocapsids, which are not recognized by the antibodies. To determine whether the antibodies were acting on an early transcription step, transcription reactions were carried out in the presence of globin mRNA (a mixture of alpha- and beta-globin chains) and only one labeled nucleoside triphosphate (either GTP or CTP). The results obtained showed that MAbs to the PB2 and NP polypeptides interfered with the initiation step of mRNA-primed transcription. The implications of these results regarding initiation of viral mRNA synthesis are discussed.

Role of EDRF/NO in parasympathetic coronary vasodilation following carotid chemoreflex activation in conscious dogs

The role of endothelium-derived relaxing factor (EDRF) in parasympathetic coronary vasodilation following carotid chemoreflex activation induced by nicotine in conscious dogs and stimulation of the vagus nerve in anesthetized dogs was studied. Injection of nicotine (11 +/- 4 micrograms) into the carotid artery increased coronary blood flow (CBF) by 126 +/- 16% from 28 +/- 3 ml/min and reduced late diastolic coronary resistance (LDCR) by 43 +/- 4% from 3.58 +/- 0.52 mmHg.ml-1.min, accompanied by a significant increase in mean arterial pressure and a decrease in heart rate (all P < 0.01). Pacing and propranolol did not change the coronary vascular response to chemoreflex activation. There were still increases in CBF by 113 +/- 17% from 29 +/- 3 ml/min and decreases in LDCR by 41 +/- 5% from 3.13 +/- 0.52 mmHg.ml-1.min (all P < 0.01). After infusion of N omega-nitro-L-arginine (L-NNA) (30 mg/kg), the increase in CBF following chemoreflex activation was only 23 +/- 3% from 37 +/- 3 ml/min, and the fall in LDCR was 19 +/- 3% from 3.09 +/- 0.51 mmHg.ml-1.min. Stimulation of the vagus nerve showed a relationship between stimulation frequency and coronary vasodilation that was significantly inhibited by L-NNA. Thus EDRF plays an important role in mediating parasympathetic coronary vasodilation during chemoreflex activation and perhaps during many reflexes that cause vagal cholinergic vasodilation in the heart.

Role of EDRF in the regulation of regional blood flow and vascular resistance at rest and during exercise in conscious dogs

The contribution of endothelium-derived relaxing factor (EDRF) to the regulation of regional vascular resistance and tissue blood flow at rest and during acute moderate exercise was studied in chronically instrumented conscious dogs. Radioactive microspheres were injected before and during exercise to measure regional blood flow. An infusion of nitro-L-arginine (L-NA), an analogue of L-arginine, was used to inhibit the synthesis of EDRF and resulted in a significant increase in mean arterial pressure, associated with significantly elevated vascular resistance in heart, skeletal muscle, renal and splanchnic circulations and with decreases in tissue blood flow in those regions at rest. Acute exercise caused a typical redistribution of blood flow, in which there was vasodilation in heart and working skeletal muscles, accompanied by vasoconstriction in kidney and splanchnic circulations. L-NA resulted in significantly elevated vascular resistance during vasodilation in heart and working skeletal muscles and also significantly increased vasoconstriction in renal cortex, stomach, pancreas, liver, and colon during exercise. Blood flows during exercise were largely unaffected by L-NA treatment. Our results suggest that whereas EDRF functions to regulate basal vascular tone and vascular resistance during exercise, EDRF has a minor role in determining the pattern of the redistribution of tissue blood flow during exercise.

Role of tachycardia and V wave wall stress in the release of ANF during volume loading

Heart rate is believed to be a primary determinant of atrial natriuretic factor (ANF) release; however, we postulated that V wave wall stress is the main signal for ANF release during volume loading. Conscious dogs were volume loaded with 1,000 ml of saline while the heart rate was allowed to vary and on another day while the heart was paced at 240 beats/min. During volume loading, plasma ANF increased from 58 +/- 10 to 221 +/- 31 pg/ml (P < 0.05), and heart rate increased from 97 +/- 3 to 182 +/- 9 beats/min. During pacing, plasma ANF increased from 42 +/- 8 to 85 +/- 10 pg/ml. A wave atrial pressures were increased during pacing and were fixed due to contraction against a closed atrioventricular valve. Volume loading increased plasma ANF to 180 +/- 25 pg/ml. V wave atrial pressure increased markedly, and V wave atrial wall stress increased from 25 +/- 10 to 131 +/- 44 and from 7 +/- 4 to 116 +/- 25 g/cm2, respectively. A wave pressure and wall stress were not increased by volume loading. V wave wall stress and ANF were significantly correlated. V wave atrial wall stress accounts for the majority of change in plasma ANF (60%), while tachycardia and A wave wall stress account for a smaller fraction (40%) of change.

Chronic elevation of norepinephrine in conscious dogs produces hypertrophy with no loss of LV reserve

Elevated plasma catecholamine levels may cause both myocardial hypertrophy and tissue damage. To determine whether the left ventricle from dogs with chronic norepinephrine infusion can sustain additional functional loads, we altered ventricular preload or afterload and determined both global and left ventricular (LV) wall function. Dogs were instrumented to measure LV wall function, LV internal base diameter, and LV pressures and were allowed to fully recover. Preload was altered by volume loading and afterload by injection of phenylephrine. Osmotic infusion pumps were implanted to continuously release norepinephrine at 0.5 micrograms.kg-1.min-1 for 28 days, and the volume loading and phenylephrine were repeated on days 14 and 28. Heart rate decreased, whereas there were no differences in mean arterial pressure, maximum first derivative of LV pressure (dP/dt), LV dP/dt/developed pressure of 40 mmHg, LV dP/dt/end-diastolic circumference, slope of the pressure-diameter relation, peak systolic wall stress, LV/end-diastolic diameter, or LV/end-systolic diameter during norepinephrine infusion. Diastolic and systolic wall thickness and chamber weights were increased (P less than 0.05). Indexes of diastolic function, including end-diastolic pressure, end-diastolic pressure-end-diastolic diameter relationship, maximum negative dP/dt, and the time constant (tau) were unchanged after chronic norepinephrine infusion, although maximum end-diastolic pressure during volume loading was increased from 17.7 +/- 2.0 to 21.7 +/- 1.0 mmHg. Chronic norepinephrine infusion did not alter tau, and tau increased equivalently with phenylephrine injection in both normal (36 +/- 1 to 62 +/- 5 ms) dogs and in those chronically infused with norepinephrine (36 +/- 1 to 56 +/- 5 ms).(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid baroreceptor function in dogs with chronic norepinephrine infusion

Carotid baroreceptor function, the compliance of the carotid sinus wall, and the structure of the carotid artery were examined in dogs with elevated plasma norepinephrine (2,000-4,000 pg/ml) for 28 days. The dogs with high norepinephrine were normotensive (100 +/- 4.0 versus 98 +/- 4.0 mm Hg; p greater than 0.05) with bradycardia (65 +/- 4.0 versus 87 +/- 16 beats/min; p less than 0.05) compared with normal dogs in the conscious state. However, after pentobarbital anesthesia blood pressure was significantly higher in dogs with chronic norepinephrine infusion (165 +/- 6 mm Hg) compared with normal dogs (132 +/- 6 mm Hg). To assess baroreceptor sensitivity, multiunit carotid baroreceptor activity was recorded from the right carotid sinus nerve, and the carotid sinus wall compliance (sonomicrometers) was measured during nitroglycerin and phenylephrine injections. The threshold and saturation pressures increased from 96 +/- 3.9 to 117 +/- 4.2 mm Hg and from 145 +/- 4.3 to 171 +/- 5.7 mm Hg, respectively, in the normal dogs compared with the high norepinephrine dogs. The most striking differences were the marked increases in sensitivity of carotid baroreceptors (0.47 +/- 0.05 versus 1.99 +/- 0.45 spikes.sec-1.mm Hg-1; p less than 0.01) and maximum firing frequency of the baroreceptors (24 +/- 3.1 versus 48 +/- 4.4 spikes/sec; p less than 0.01), whereas the carotid sinus wall compliance was unchanged (0.014 +/- 0.003 versus 0.012 +/- 0.002 mm/mm Hg; p greater than 0.05). Similar alterations were observed using single fiber recordings, that is, an increase in threshold and saturation pressures and slope of baroreceptor units in dogs with elevated norepinephrine. The wall thickness and area of the carotid artery were determined. Both increased significantly (0.77 +/- 0.06 versus 1.30 +/- 0.12 mm and 9.0 +/- 0.8 versus 11.9 +/- 0.9 mm2; p less than 0.05) in dogs chronically infused with norepinephrine while the dry weight-to-wet weight ratio of left carotid artery tissue also increased from 26.0 +/- 0.73% to 29.0 +/- 0.57%. These studies indicate that 1) one of the possible mechanisms responsible for bradycardia in the conscious dogs with high norepinephrine is enhanced sensitivity of carotid baroreceptors; 2) the enhanced sensitivity of carotid baroreceptors is not due to a change in compliance of the carotid sinus wall; and 3) chronic elevation of norepinephrine causes hypertrophy or hyperplasia of the wall of the common carotid artery.

Regulation of plasma ANF after increases in afterload in conscious dogs

Although atrial stretch is the primary stimulus for atrial natriuretic factor (ANF) secretion, hormones may directly affect ANF secretion or may indirectly influence ANF by changing left ventricular afterload, thereby altering atrial stretch. To determine whether direct effects are important for the release of ANF in vivo, we measured changes in plasma ANF and in atrial wall function in the conscious dog after the administration of vasopressin, angiotensin II, and phenylephrine and by mechanically increasing left ventricular afterload by partial aortic occlusion. Injections of phenylephrine, angiotensin II, and arginine vasopressin (AVP) that were chosen to cause similar changes in systemic arterial pressure resulted in similar changes in atrial pressure and diameter. Maximum V wave atrial wall stress increased to 283 +/- 12, 311 +/- 41, 327 +/- 24, and 277 +/- 22 g/cm2 for AVP, angiotensin, phenylephrine, and occlusion, respectively, and plasma ANF increased to 242 +/- 81, 248 +/- 62, 299 +/- 95, and 190 +/- 53 pg/ml. There were significant linear correlations between left ventricular afterload and left atrial pressure, and each method for increasing left ventricular afterload shifted the position to the left on an atrial pressure-diameter, compliance curve, by a similar degree. Thus changes in left ventricular afterload result in changes in atrial wall function and similar changes in plasma ANF. No hormonal-specific increase in plasma ANF was found in conscious dogs after increases in afterload.

Dynamics of atrial peptide secretion in the coronary circulation of the conscious dog

The secretion of atrial natriuretic peptide by the heart is not simply the arterial-coronary sinus concentration difference times coronary blood flow, because only a small fraction of total coronary blood flow passes through the atria. We measured coronary sinus and arterial plasma atrial natriuretic factor (ANF) concentrations and blood flow to each part of the heart using the radioactive microsphere technique. Before acute volume expansion, the arterial-coronary sinus ANF difference was 305 +/- 23 pg/ml and rose to 1,009 +/- 220 pg/ml during volume expansion, whereas total coronary blood flow rose from 167 to 465 ml/min. Atrial blood flow rose from 2.9% to 4.6% of total coronary blood flow during volume expansion. ANF secretion rate increased from 51 to 469 ng/min. When divided by atrial weight, ANF secretion rate increased from 4.0 +/- 0.3 to 56 +/- 12 ng/min/g atrial tissue-in other words, from 0.3% to 3.7% of tissue ANF content each minute. Dividing by atrial blood flow indicated that the concentration of ANF leaving atrial tissue was 10,000 to 29,651 pg/ml, and the additional secretion of ANF was determined by the increase in coronary blood flow. Therefore, at least two mechanisms are responsible for altering coronary sinus ANF and circulating ANF: the release rate from atrial myocytes and the washout via changes in atrial blood flow.

Intraperitoneal cisplatin and etoposide in the treatment of refractory/recurrent ovarian carcinoma

To determine the efficacy of a 6-month course of combination intraperitoneal (IP) chemotherapy with cisplatin and etoposide in patients with refractory or recurrent advanced ovarian carcinoma, 67 patients were entered into this prospective, nonrandomized, single-institution trial. Cisplatin at 100 mg/m2 and etoposide at 200 mg/m2 were administered IP on day 1 every month for 6 months. Exploratory laparotomy was performed before protocol entry and was planned after the completion of 6 months of IP therapy to surgically document response. All patients had received prior intravenous (IV) chemotherapy with a cisplatin-based regimen. At protocol entry, 18 (27%) patients had surgically defined residual tumor (maximal tumor diameter) greater than 2.0 cm, 17 (25%) patients greater than 0.5 cm - less than or equal to 2.0 cm, and 32 (48%) patients less than or equal to 0.5 cm. Sixteen patients (24%) who had experienced a treatment-free interval of more than 1 year prior to study entry were considered as having recurrent disease and the remaining 51 (76%) patients were considered as having refractory disease. Toxicity was tolerable: four patients (6%) had nadir fever, three (4%) had culture-documented bacterial peritonitis, five (7%) had IP catheter-related complications, and 27 (40%) had an increase in serum creatinine greater than 1.5 mg/dL. Among the 57 patients who are fully evaluable for response, the overall surgically defined response rate, complete (CR), and partial response (PR), was 40% (23/57), and the CR rate was 21% (12/57). Among the patients with recurrent disease, eight of 13 (62%) responded, with responses seen among all categories of residual disease. Among the patients with refractory disease, 15 of 44 (34%) had surgically documented responses. However, responses were more frequent in patients with residual disease less than 0.5 cm; 11 of 20 (55%) versus four of 24 (17%) with residual greater than 0.5 cm, P = .019 (chi 2, one degree of freedom, Yates correction). The duration of the CRs ranges from 4 to 18+ months. Longer follow-up is needed to determine if there is any impact on survival.

Clinical trial of iproplatin (cis-dichloro-trans-dihydroxy-bis-isopropylamine platinum IV, CHIP) in patients with advanced breast cancer

Twenty-five women with advanced breast cancer were treated in a phase II trial of iproplatin 275 mg/m2 administered intravenously every 4 weeks. All patients had measurable or evaluable indicator lesions, and had undergone treatment with no more than one previous chemotherapy regimen, including adjuvant chemotherapy. Two of the twenty-four evaluable patients (8%) experienced major therapeutic responses. One patient had a complete regression of pulmonary nodules lasting 18+ months; another had a partial regression of metastatic disease in the liver (4 months). The inevaluable patient was ineligible for the study because of previous radiation to the indicator lesions on her chest wall; nonetheless, she experienced a 10 month partial regression of those nodules. Myelosuppression was generally dose limiting; thrombocytopenia was more profound, but leukopenia was more prolonged. Nausea, vomiting, diarrhea, and general malaise were prominent toxicities, and led to discontinuation of therapy in 4 patients. Iproplatin has limited activity in previously treated women with advanced breast cancer.

A review of second-look laparotomy for ovarian cancer

One hundred twenty-seven patients underwent second-look laparotomies from July 1969 to June 1982. To be included in this report they must have met the following criteria: a documented ovarian neoplasm; previous surgery; adequate chemotherapy for cessation if no disease was found; and no X-ray, chemical, or clinical evidence of disease including an exam under anesthesia. Forty-one percent had residual disease at second-look laparotomy. The original stage and the percentage of tumor debulked at initial surgery were inversely related to the likelihood of finding residual disease. Age, histologic type and grade, and type of chemotherapy did not show a significant relationship with the likelihood of disease persisting. Recurrent tumor was subsequently detected in 16% of patients who had been found to be free of disease at second-look laparotomy. Of thirty stage III and IV patients treated with combinations containing cis-platinum, 10 (33%) had recurrences. This rate of recurrence was significantly greater than the 17.6% recurrence rate in 17 patients with Stage III and IV disease whose chemotherapy consisted of single alkylating agents or with combinations without cis-platinum. Twenty patients underwent a third-look laparotomy after completion of additional chemotherapy. Nine were found to have no residual disease. Two of the nine (22%) subsequently had recurrence of disease. Three of the eleven patients with persistent disease at the time of a third-look laparotomy underwent a fourth-look laparotomy. All were found free of disease and none have recurred. Six (55%) of those with persistent disease at the third-look laparotomy have died despite continued therapy. The ability to successfully treat some patients with persistent disease continues to be a justification for the use of a second-look laparotomy. However, the high rate of recurrence after cessation of treatment following the finding of no residual disease raises the question of whether it is appropriate to discontinue all therapy at this time.

Adenocarcinoma of unknown primary origin: treatment with vindesine and doxorubicin

Adenocarcinoma of unknown primary origin (ACUP) is a common oncologic problem for which there is no standard therapy. Forty-two patients with metastatic tumor were identified as having ACUP after extensive evaluation failed to reveal a primary site of disease. They were treated with an investigational chemotherapy regimen consisting of vindesine and doxorubicin. Of the 38 evaluable patients, six (16%) had major responses to chemotherapy. The median duration of response was 4 months. The median survival of the responding patients has not been reached, but is greater than 8 months. The median survival of the nonresponding patients was 6 months. Vindesine and doxorubicin were well tolerated. The major toxicity was leukopenia, with a median wbc count nadir of 2600/mm. We conclude that the combination of vindesine and doxorubicin has some activity in ACUP, but does not improve the response rate seen with other regimens.

Long-term follow-up of children breast-fed by mothers receiving depot-medroxyprogesterone acetate

A long-term follow-up study compared development and health of 128 breast-fed children whose mothers had received depot-medroxyprogesterone acetate (depot-MPA) while lactating and 142 control children whose mothers had used mechanical contraceptives or no contraceptives or had undergone sterilization. The children, who were approximately 4-1/2 years old at follow-up, showed no ill effects on their growth and development and health status from exposure to depot-MPA. Depot-MPA-treated mothers lactated significantly longer than controls and also had greater parity than controls. These factors apparently contributed to a difference in weight at follow-up. Compared with the Sempe-Pedron standard, more of the depot-MPA group were underweight and more controls were overweight.

Differentiation stimuli induce receptors for plasma fibronectin on the human myelomonocytic cell line HL-60

Plasma fibronectin (Fn) induces phagocytosis of C3b-opsonized sheep erythrocytes (EC3b) by human peripheral blood monocytes. However, Fn does not induce erythrophagocytosis of EC3b by human polymorphonuclear leukocytes (PMN), unless the PMN have been exposed to C5a or N-formyl-methionyl-leucyl-phenylalanine. Because of this difference, it is of great interest to examine Fn binding to cells that possess the capacity to differentiate into either granulocytes or monocytes. Hence, we have examined the consequences of Fn binding to the human myelomonocytic cell line, HL-60, both before and after in vitro differentiation of the HL-60, along a monocytoid or a granulocytoid pathway. Fn receptors were not found on undifferentiated HL-60, but several differentiating agents promoted the HL-60 binding of Fn-coated microspheres (Fn-ms). The peak of Fn-ms binding occurred four to five days after the induction of differentiation with dimethylsulfoxide (DMSO), and two days after induction by PMA. In addition, cells that differentiated along either the monocytoid or the granulocytoid pathway showed a marked increase in the phagocytosis of both IgG-coated erythrocytes (EA) and EC3b when they were exposed to Fn. Comparison of the effects of anti-Fn monoclonals on the binding of Fn-ms to the monocytes, PMN, and HL-60 showed that the same monoclonals block Fn-ms-binding and Fn-induced EC3b phagocytosis by all three cell types. Two monoclonal antibodies, M1/70 and A6F10, directed against membrane antigens on PMN and monocytes, inhibited Fn-ms binding. Both also blocked Fn-induced EC3b ingestion by these cells. However, neither antibody blocked Fn-ms binding or EC3b ingestion by differentiated HL-60. We conclude that differentiated HL-60 cells express functionally active Fn receptors, similar to monocytes and activated PMN, which, nonetheless, differ from normal cells in their association with the antigens recognized by M1/70 and A6F10.

Germ cell malignancies of the ovary: treatment with vinblastine, actinomycin D, bleomycin and cisplatin containing chemotherapy combinations

Seventeen patients with malignant ovarian germ cell tumors were treated with vinblastine, actinomycin D, bleomycin and cisplatin containing combinations. Many of these patients were heavily pretreated. Thirteen patients had objectively measurable disease and ten (77%) had an objective response (CR or PR). Four patients had nonmeasurable disease or were treated in an adjuvant setting and all remain without evidence of disease. Extensive disease and poor performance status were poor prognostic factors. Induction portions of these treatment programs which contained cisplatin appeared most effective. Maintenance portions without cisplatin appeared less effective.

Immunology of human gastric cancer: a preliminary report

The immunological spectrum in fifteen patients with gastric cancer is presented. Patients were divided in three groups. Those with nonadvanced cancer, those with advanced but resectable lesions and those with advanced but nonresectable tumors. Preoperatively, elevated levels of circulating immune complexes (CIC) associated with hyporesponsiveness to phytohemagglutinin (PHA) and in mixed lymphocyte culture (MLC) as well as a positive leukocyte inhibitory serum factor (LIF-S) were found in nearly half of the patients. Inhibitory or enhancing autologous serum factors were detected. Postoperatively, immunologic parameters return to normal in patients with nonadvanced cancer, while in advanced cancer, antibody and cell-mediated immune response remained altered, with some changes associated with chemotherapy. These findings are probably related with the presence or absence of tumor and offer a distinct approach in evaluating the immunologic response of a tumor-bearing patient.

Outbreak of Kaposi's sarcoma with cytomegalovirus infection in young homosexual men

Kaposi's sarcoma, a multicentric malignant neoplasm, occurs in certain geographic areas in the world. It is most common in Equatorial Africa and Eastern Europe. The annual incidence of Kaposi's sarcoma in the United States is between 0.021 and 0.061 per 100,000 persons. The appearance of an outbreak of Kaposi's sarcoma in young homosexual men in New York and California is a new and unique phenomenon. Certain differences are already recognized between the disease in these young men and the ordinary Kaposi's sarcoma. Herein we report our observations of the first 10 cases of Kaposi's sarcoma in young homosexual men. In these patients, the disease follows an aggressive clinical course characterized by widespread skin lesions with early involvement of the lymph nodes. In some of these patients, the result was death in a short period of time after initial diagnosis. In addition, cytomegalovirus infections were seen in these patients, which suggests at least a possible association between this viral and the disease.