The role of citizen science in addressing grand challenges in food and agriculture research.

The power of citizen science to contribute to both science and society is gaining increased recognition, particularly in physics and biology. Although there is a long history of public engagement in agriculture and food science, the term 'citizen science' has rarely been applied to these efforts. Similarly, in the emerging field of citizen science, most new citizen science projects do not focus on food or agriculture. Here, we convened thought leaders from a broad range of fields related to citizen science, agriculture, and food science to highlight key opportunities for bridging these overlapping yet disconnected communities/fields and identify ways to leverage their respective strengths. Specifically, we show that (i) citizen science projects are addressing many grand challenges facing our food systems, as outlined by the United States National Institute of Food and Agriculture, as well as broader Sustainable Development Goals set by the United Nations Development Programme, (ii) there exist emerging opportunities and unique challenges for citizen science in agriculture/food research, and (iii) the greatest opportunities for the development of citizen science projects in agriculture and food science will be gained by using the existing infrastructure and tools of Extension programmes and through the engagement of urban communities. Further, we argue there is no better time to foster greater collaboration between these fields given the trend of shrinking Extension programmes, the increasing need to apply innovative solutions to address rising demands on agricultural systems, and the exponential growth of the field of citizen science.

Effects of human polymorphonuclear leukocyte elastase upon surfactant proteins in vitro.

Recent evidence has suggested that elastase is released by polymorphonuclear leukocytes (PMN) recruited from the pulmonary microcirculation into the alveoli during acute lung injury. This study was undertaken to test the hypothesis that elastase from PMN (PMN elastase) damages or degrades one or more of the surfactant proteins (SP-A, SP-B and SP-C) of the lung, and thereby alters its function. We attempted to use amounts of PMN elastase and quantities of surfactant that would be plausible in the lungs of patients with ARDS. Surfactant from normal dog lungs (2 mg phospholipid, 200 micrograms protein), and purified SP-A (20 micrograms), SP-B (10 micrograms) and SP-C (10 micrograms) from the surfactant (identified by SDS-PAGE and N-terminal amino acid sequences) were incubated for 4-8 h at 37 degrees C with various amounts (0.25-1.0 U) of human PMN elastase purified by affinity chromatography. SDS-PAGE and amino acid composition analysis of the surfactant as well as of the purified SP-A, SP-B, and SP-C showed that degradation of these proteins progressed with incubation time and with the amount of PMN elastase, and was accompanied by decreases in isopycnic density (g/cm3) and surface adsorption, and increase of surface tension of the surfactant. No effects were observed with heat inactivated PMN elastase (95 degrees C, 30 min) or with PMN elastase in the presence of human alpha-1 protease inhibitor (2 micrograms/microgram elastase). Phospholipid compositions of the surfactant after exposure to PMN elastase were not significantly different from those of the controls, suggesting that SP-A, SP-B, and SP-C play a major role in altering the surfactant properties. SP-A was also degraded by elastase and trypsin from pancreas whereas SP-B and SP-C remained intact, providing a natural surfactant without SP-A. Surface adsorption rate of the SP-A deficient surfactant was lower than that of the control, but was much higher than that of the surfactant with completely degraded SP-A, SP-B, and SP-C, suggesting that hydrophobic SP-B and SP-C are the essential components in enhancing adsorption. We conclude that proteolytic degradation of SP-A, SP-B, and SP-C causes the decrease of surfactant isopycnic density, and is responsible for retarding adsorption resulting in surfactant dysfunction.

Lysolecithin acyltransferase and alveolar phosphatidylcholine palmitate in experimental acute alveolar injury in the dog lung.

Lysolecithin acyltransferase (EC 2.3.1.23) activities in lung homogenates and in subcellular fractions, and fatty acid composition of phosphatidylcholine (PC) in lung lavage were studied in dogs with acute alveolar injury induced by N-nitroso-N-methylurethane. The specific activity in the microsomal fraction was 10 and 3 times higher than those of homogenate and mitochondrial fractions, respectively. Both the lysolecithin acyltransferase activities and the proportions of palmitate in alveolar lavage PC increased during the early phase of injury (days 2-4), and decreased during peak injury (days 6-8). Such correlation was not found during the recovery period (day 15). During recovery, specific and total activities of the enzyme were nearly 2- and 3-fold, respectively, those of controls. Nevertheless, the palmitate proportions in PC were normal, indicating that the increased enzyme activity in vitro was not reflected in increased PC palmitate during recovery. This finding indicates that the enzyme activity per cell was normal during recovery and suggests that the increase in specific and total activities is due to massive regeneration of type II cells and that the enzyme is localized mainly in these cells. The decrease in the proportion of palmitate in lavage PC during peak injury may lead to abnormality of surfactant function.

The ultrastructure of neurilemoma with emphasis on Antoni B tissue.

Ten neurilemomas were studied by electron microscopy. Antoni A and B tissues were identified by light microscopy on semithin sections, and the corresponding areas on adjacent ultrathin sections were studied ultrastructurally. The Antoni B tissue definitely possessed features of degeneration in that the cells showed a detached basal lamina, a disrupted cell membrane, degenerated nuclei, and a significant accumulation of cytoplasmic granules and myelin figures. Added to these was intercellular edema with fibrin. The similarity of the granules in the cells of Antoni B tissue, cells of granular cell tumor, and Schwann cells in wallerian degeneration supports the conclusion that these three are related phenomena.

Alveolar epithelial injury causing respiratory distress in dogs: physiologic and electron-microscopic correlations.

Structural and mechanical changes were correlated in 29 dogs with acute alveolar injury induced by the subcutaneous administration of N-nitroso-N-methylurethane (NNNMU). The injury was characterized by necrosis and repair of alveolar epithelium while the vascular endothelium remained essentially intact. Compliance of the lung (CL) decreased and elastic recoil increased as epithelial necrosis occurred. During recovery, improved elastic recoil coincided with epithelial regeneration, although CL remained abnormal. The late phase was characterized histologically by widespread closure of clusters of alveoli alternating with dilated small air spaces. The process resulted in distortion of lung architecture and resembled interstitial fibrosis. Reduced lung volume and decreased distensibility of dilated small air spaces may have accounted for the persistently abnormal CL. Because of the specific site of anatomic involvement, the predictable evolution of deranged lung mechanics, and the similarity to human lung injury (adult respiratory distress syndrome), the lung injured by administration of N-nitroso-N-methylurethane is a suitable model to study pathophysiology and types of therapy in a controlled setting.

Adipose cell morphology and control of lipolysis in a patient with partial lipodystrophy.

A previously unreported patient with partial (cephalothoracic) lipodystrophy is described. Glucose tolerance and plasma lipids were normal, but plasma insulin increased to 340 muU/ml during an oral glucose tolerance test. Plasma free fatty acids were appropriately suppressed by oral glucose, insulin, and nicotinic acid, and were increased by infusion of norepinephrine. The lipolytic responses was also normal in response to two stimuli for endogenous catecholamine release: upright posture and 2-deoxyglucose infusion. There was a gradual development of postural hypotension in response to upright posture despite appropriate reflex tachycardia. Anhidrosis was present over the lower half of the body during this test, in a distribution corresponding to the area of adipose tissue hypertrophy. Anhidrosis was also seen in this region in response to warm ambient temperature. Adipose cells from the atrophic area were smaller than those from the hypertropic area, but the atrophic cells were only 65% of the volume of the hypertrophic cells by two different methods. Thus, loss of cells occurred. Glucose-1(-14)C utilization and in vitro lipolysis were similar in the two cell preparations; the difference were explicable by cell size and did not suggest a metabolic abnormality. Counts of unmyelinated nerves were similar in the two areas. These findings indicate that in this patient the lipodystrophy was associated with normal fat cells and an autonomic dysfunction. However, the findings cannot completely explain the pathogenesis of her disorder. Loss of fat cells, rather than symmetrical shrinkage, occurred in the upper half of the body.

Human pulmonary dirofilariasis: does diagnosis require thoracotomy?

The incidence of pulmonary coin lesions as a result of Dirofilaria immitis (dog heartworm) seems to be increasing. A case of human pulmonary dirofilariasis is described, and its pathogenesis and the limitations of preoperative diagnostic tests in this condition are discussed.

Purification of surfactant protein A from dog lung by reconstitution with surfactant lipids.

We have developed a simple method for purification of surfactant major apoprotein (SP-A, MW 34-38 kD) from dog lungs with high yield and purity. Lipids and proteins of partially purified surfactant were dissociated by sodium deoxycholate (DOC, 100 mM, 37 degrees C, 30 min), diluted 1:10 with borate buffer containing 3 mM CaCl2, and dialysate in the same buffer to reconstitute the lipids and proteins (4 degrees C, 48 h). The reconstituent and the partially purified surfactant were purified by ultracentrifugation on a discontinuous sucrose density gradient. Protein was isolated from the reconstituent and from the purified surfactant by delipidation, and the yields and purities were assessed by one-dimensional SDS-PAGE and 2-dimensional electrophoresis (isoelectric focusing, SDS-PAGE). We found that the surface pressure-time adsorption isotherm, minimum surface tension, and the yield and composition of lipids of the reconstituent were identical with those from the purified surfactant. Only about 0.25% of the DOC used for dissociation remained with the reconstituent and it did not affect surface properties of the reconstituent. The yield of SP-A in the reconstituent was almost the same as that in the purified surfactant, but the former contained no plasma protein whereas the latter contained significant amounts. The amino acid composition and the partial N-terminal amino acid sequence of SP-A were the same as those from the purified surfactant. Reconstituent prepared from surfactant lipids and SP-A adsorbed more rapidly and reached a higher final surface pressure than did the surfactant lipids alone. These results demonstrate that large quantities of SP-A can be purified by reconstitution with surfactant lipids, and that the purified protein is biophysically active.

Steatosis of granular pneumocytes in alcoholics with acute alveolar injury.

Accumulation of neutral lipid in the type II alveolar epithelial cells of the lung has been described in experiments involving animals with conditions such as hypoxia or on alcohol administration. In two cases involving human subjects, this change was observed at autopsy by histochemical stains and electron microscopy. In both instances, the patients had had severe alcoholic liver disease, as well as extreme hypoxia resulting from acute alveolar injury. The lungs of six alcoholic patients with liver disease but without acute alveolar injury showed no lipid vesicles on histochemical staining. These observations suggest that a metabolic insult or combination of insults, such as alcohol or hypoxia, might lead to accumulation of neutral lipid, especially in regenerating alveolar epithelial cells that may be more susceptible to such injury.

Isolation of human polymorphonuclear leukocyte elastase by chromatography on immobilized benzamidine.

Recent evidence suggests that polymorphonuclear leukocyte (PMN) elastase causes tissue injury in a variety of diseases. Current methods of purification of elastase involve several steps which result in a low yield. We report a simple purification method. PMN (10(9) in 4 ml of 0.05 M Tris, pH 7.8, containing 0.2% Triton X-100 were disrupted and homogenized by freezing and thawing followed by sonication. After centrifugation at 100,000 g for 20 min, enzyme was extracted from the pellet with 2.5 ml of 0.05 M Tris/1M NaCl (pH 7.8). The centrifugation-extraction cycle was repeated 3 times. Elastase from 10(8) PMN was then purified using a 1 ml Protease Inhibitor Affinity-Filter prepared by binding benzamidine to silica. Enzyme activity was determined by cleavage of the synthetic substrate N-Suc-(Ala)3-pNa. SDS-PAGE demonstrated 2 polypeptides, molecular masses of 29 and 27 kD with amino acid composition and partial N-terminal sequence (Ile-Val-Gly-Gly-Arg-Arg-Ala-Arg-Pro-His-Ala-Trp-Pro-) identical with those previously reported for elastase. We obtained 50 micrograms elastase (34-fold purification) with specific activity of 52 U/mg/min from 10(8) PMN. This represents a much greater recovery (23% yield) than is achieved by other methods. This method is simple, highly reproducible, and can be performed within a 2-day period.

Effects of activated polymorphonuclear leukocytes upon pulmonary surfactant in vitro.

Current evidence suggests that products of activated inflammatory cells cause or contribute to the acute lung injury of the adult respiratory distress syndrome (ARDS). To assess the possibility that these products may impair surfactant function during ARDS, we exposed surfactant in vitro to polymorphonuclear leukocytes (PMN) activated by phorbol myristate acetate and to the oxidant-producing pair ferric chloride/ascorbate (FeCl3/ASC). After incubation of surfactant with 8 to 32 x 10(6) activated PMN for 1 to 4 h or with FeCl3/ASC for 16 h, its isopycnic density (d), minimum surface tension (gamma min), time course of adsorption, compressibility (SC), and stability index (SI) were determined. We found progressive decreases of d, adsorption, and SI and progressive increases of gamma min and SC after exposure to activated PMN in increasing numbers or for longer time periods. Superoxide dismutase completely inhibited all of these effects except the decreased adsorption, which it did not significantly inhibit. Similar changes in all of these parameters occurred after exposure of surfactant to FeCl3/ASC. Polyacrylamide gel electrophoresis of surfactant after exposure to activated PMN showed a decrease of the major apoprotein that progressed with exposure time and was associated with the appearance of several bands with both lower and higher molecular weights than that of the apoprotein. The data show that activated PMN are capable of impairing surfactant function in vitro and of degrading the major apoprotein. They suggest that the effects upon d, gamma min, SC, and SI are mediated largely if not exclusively by oxidant radicals. While oxidants may contribute to delayed adsorption, proteolysis appears to play the principal role in this effect.

Effect of positive end-expiratory pressure on lung compliance in dogs after acute alveolar injury.

We studied the effect of positive end-expiratory pressure (PEEP) on lung compliance (CL) in 17 dogs during the early phase of acute alveolar injury induced by the subcutaneous administration of N-nitroso-N-methylurethane (NNNMU). The acute phase of this injury is characterized by necrosis of the alveolar epithelium and by decreased CL, which is caused by abnormal surface forces and which correlates with decreased alveolar surfactant lipids. During the control period and after NNNMU both CL decreased significantly with increments of PEEP (p less than 0.001) and plots of FRC versus PEEP had a rising curve with a decreasing slope. Static volume-pressure curves obtained in vivo in 6 dogs showed a rightward shift of the curve without increase of hysteresis after NNNMU. these data suggest that in the surfactant-deficient lung, PEEP predominantly causes overdistention of patent alveoli rather than recruitment of closed air spaces. The physiologic response of the NNNMU-injured lung to PEEP differs from that of severely edematous lungs but is similar to that of surfactant-deficient lungs of premature lambs.

Experimental acute alveolar injury in the dog. Morphologic--mechanical correlations.

In 26 dogs, a single subcutaneous injection of N-nitroso-N-methylurethane produced acute lung injury characterized by tachypnea cyanosis, increased static lung recoil, and decreased lung compliance. During the first few days, light microscopic examination revealed widespread interstitial and perivascular edema and alveolar collapse. At the same time, electron microscopy showed the major alteration to be widespread necrosis of both types of alveolar epithelial cells without significant injury to the vascular endothelium. During recovery, new epithelial cells appeared which probably were derived from granular pneumocytes. These cells developed into mature granular pneumocytes through a phase in which they resembled fetal granular pneumocytes. The late stage was characterized by a picture resembling diffuse interstitial fibrosis but which was due to irreversible closure of clusters of small airspaces with no apparent increase in collagen. Elastic recoil of the lungs, as reflected by peak inspiratory airway pressure, increased during the acute phase and showed a return toward normal that was coincident with the appearance of mature granular pneumocytes in the regenerating epithelium. Lung compliance decreased during the acute phase and in most animals returned toward normal during the recovery phase. These observations strongly suggest that the alteration in lung mechanics is related to epithelial necrosis and that recovery is related to epithelial regeneration.

Functional abnormalities of lung surfactant in experimental acute alveolar injury in the dog.

Acute alveolar injury (AAI) was induced in dogs by injection of N-nitroso-N-methylurethane. Two to 20 days after injection, alveolar lavage phospholipids were quantified. Lavage surfactant was partially purified by centrifugation (27,000 g for 2 h), and further purified by centrifugation in NaBr density gradient (100,000 g for 4 h). Phospholipids, neutral lipids, surfactant-associated proteins, and surface properties of partially purified and purified surfactants were analyzed. Lavage disaturated phosphatidylcholine (DSPC) decreased to 37% of control at peak injury (Days 6 to 8) and increased to near normal during recovery (Days 10 to 20). Lavage phosphatidylglycerol (PG) decreased to 22% of control at peak injury and remained in that range through recovery. In both partially purified and purified surfactants, percentages of phosphatidylcholine (PC), DSPC, phosphatidylethanolamine, and cholesterol in all phases of injury and recovery were not different from those in control animals. However, percentage of PG decreased markedly during injury and remained low through recovery, whereas those of phosphatidylinositol and lysoPC increased with injury and remained elevated through recovery. The PC-to-sphingomyelin ratio (L/S ratio) and percentage of triglyceride decreased during injury and returned to control values during recovery. Surfactant apoprotein of molecular weight 38,000 from partially purified and purified surfactant decreased markedly at peak injury and recovered to normal during recovery. During early and peak injury, both preparations failed to reduce surface tension below 19 dyne/cm and their isopycnic densities were altered. These studies indicate that, in addition to decreased quantity, qualitative changes in lipids and apoproteins and reduced surface activity of the surfactant occur during nitrosourethane-induced AAI.(ABSTRACT TRUNCATED AT 250 WORDS)

The distribution of atherosclerotic lesions in the coronary arterial tree: relation to cardiac risk factors.

Although it is often stated that proximal atherosclerotic coronary artery disease occurs more frequently than distal disease, several autopsy studies have disputed this. To examine the prevalence of proximal vs mid and distal disease and its relationship with cardiac risk factors, we studied more than 14,000 sections from 102 hearts with coronary artery disease at autopsy. After postmortem angiography, the coronary arteries were removed, divided into proximal, mid, and distal thirds, sectioned at 2.5 mm intervals, and graded for percentage reduction in cross-sectional area by atherosclerosis. Of 252 vessels in 84 patients with greater than or equal to 75% stenosis, 166 (66%) has proximal disease vs 107 (42%) with mid disease and 40 (16%) with distal disease (p less than 0.001). No patient had a mid or distal stenosis greater than 75% without proximal disease. When atherosclerosis of any severity was assessed, proximal atherosclerotic lesions were long and diffuse, whereas distal lesions were more often short and discrete. Proximal circumflex lesions were shorter in length than those in the right or left anterior descending coronary arteries. The prevalence of proximal, mid, and distal stenoses in 25 diabetic patients was similar to that in nondiabetic persons (53%, 47%, and 17%, p greater than 0.3). Similarly, hypertension, smoking, and obesity were not associated with an increase in prevalence of distal disease. Patients with distal stenoses were younger than patients without (mean age, 64 +/- 13 vs 73 +/- 10 years, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)