Naringenin Orchestrates and Regulates the Reactive Oxygen Species-Mediated Pathways and Proinflammatory Signaling: Targeting Hallmarks of Aging-Associated Disorders

The therapeutic application of flavonoids in the management of infectious diseases, cancers, chronic wounds, aging, and neurodegenerative disorders has been well documented in scientific literature. The citric flavonoid naringenin comes under the category of flavanone and exhibits a plethora of health benefits. Very few flavonoids such as curcumin, resveratrol, catechin, quercetin, and kaempferol have been studied to exert their anti-aging properties in humans. The effect of naringenin in the context of age-associated disorders in detail has not been elucidated yet. The databases used for the literature search were Science Direct, Google Scholar, and PubMed. More emphasis has been put on the recent literature on "naringenin" and its effect on "age-associated disorders." Almost all chronic degenerative disorders are characterized by oxidative stress and inflammatory response. The study aims at highlighting the reactive oxygen species-mediated activity of naringenin and the underlying molecular mechanism leading to the prevention of various age-associated disorders. Altogether, the review presents a systematic comprehension of the pharmaceutical and clinicopathological benefits of naringenin in age-associated disorders.

Assessment of MMP14, CAV2, CLU and SPARCL1 expression profiles in endometriosis

Endometriotic cells exhibit a notable degree of invasiveness and some characteristics of tissue remodeling underlying lesion formation. In this regard, do matrix metalloproteinases 14 (MMP14) and other related genes such as SPARC-like protein 1 (SPARCL1), caveolin 2 (CAV2), and clusterin (CLU) exert any significant influence in the processes of endometriosis development and pathophysiology is not apparent. We aim to assess whether these genes could serve as potential diagnostic biomarkers in endometriosis. Microarray-based gene expression analysis was performed on total RNA extracted from endometriotic tissue samples treated with and without gonadotropin-releasing hormone agonist (GnRHa). The GnRHa untreated patients were considered the control group. The validation of genes was performed using quantitative real-time polymerase chain reaction (qRT-PCR). qRT-PCR analysis showed significant downregulation in the expression of MMP14 (p = 0.024), CAV2 (p = 0.017), and upregulation of CLU (p = 0.005) in endometriosis patients treated with GnRHa. SPARCL1 did not show any significant (p = 0.30) change in the expression compared to the control group. These data have the potential to contribute to the comprehension of the molecular pathways implicated in the remodeling of the extracellular matrix, which is a vital step for the physiology of the endometrium. Based on the result, it is concluded that changes in the expression of MMP14, CAV2, and CLU post-treatment imply their role in the pathophysiology of endometriosis and may serve as a potential diagnostic biomarker of endometriosis in response to GnRHa treatment in patients with ovarian endometrioma.

DUX4 is a multifunctional factor priming human embryonic genome activation

Double homeobox 4 (DUX4) is expressed at the early pre-implantation stage in human embryos. Here we show that induced human DUX4 expression substantially alters the chromatin accessibility of non-coding DNA and activates thousands of newly identified transcribed enhancer-like regions, preferentially located within ERVL-MaLR repeat elements. CRISPR activation of transcribed enhancers by C-terminal DUX4 motifs results in the increased expression of target embryonic genome activation (EGA) genes ZSCAN4 and KHDC1P1. We show that DUX4 is markedly enriched in human zygotes, followed by intense nuclear DUX4 localization preceding and coinciding with minor EGA. DUX4 knockdown in human zygotes led to changes in the EGA transcriptome but did not terminate the embryos. We also show that the DUX4 protein interacts with the Mediator complex via the C-terminal KIX binding motif. Our findings contribute to the understanding of DUX4 as a regulator of the non-coding genome.

Immunogenic SARS-CoV-2 Epitopes: In Silico Study Towards Better Understanding of COVID-19 Disease-Paving the Way for Vaccine Development

The emergence of the COVID-19 outbreak at the end of 2019, caused by the novel coronavirus SARS-CoV-2, has, to date, led to over 13.6 million infections and nearly 600,000 deaths. Consequently, there is an urgent need to better understand the molecular factors triggering immune defense against the virus and to develop countermeasures to hinder its spread. Using in silico analyses, we showed that human major histocompatibility complex (MHC) class I cell-surface molecules vary in their capacity for binding different SARS-CoV-2-derived epitopes, i.e., short sequences of 8-11 amino acids, and pinpointed five specific SARS-CoV-2 epitopes that are likely to be presented to cytotoxic T-cells and hence activate immune responses. The identified epitopes, each one of nine amino acids, have high sequence similarity to the equivalent epitopes of SARS-CoV virus, which are known to elicit an effective T cell response in vitro. Moreover, we give a structural explanation for the binding of SARS-CoV-2-epitopes to MHC molecules. Our data can help us to better understand the differences in outcomes of COVID-19 patients and may aid the development of vaccines against SARS-CoV-2 and possible future outbreaks of novel coronaviruses.

Biochemical and molecular characterization of wild-type and fused protoplasts of Beauveria bassiana and Metarhizium anisopliae

Protoplasts were isolated from two isolates each of Beauveria bassiana and Metarhizium anisopliae using lysing enzymes. Intra- and intergeneric protoplast fusion has been carried out using 40% polyethylene glycol. The fused protoplasts of B. bassiana and M. anisopliae have been regenerated on Czapek-Dox agar media, and a total of four fusants were selected for further studies. An increase in proteinase and chitinase enzyme activity was recorded with all fusants as compared to the wild-type isolates. To understand the nature of recombination process, random amplification of polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP) were carried out on genomic DNA of fused and wild-type isolates. The present study demonstrates the scope and significance of the protoplast fusion technique as a rapid consistent method for identification of B. bassiana and M. anisopliae fused and wild-type isolates based on the banding pattern of RAPD and RFLP that can be reliably used ahead for further applications on these species.

Effects of ozone on airway epithelial permeability and ion transport

Ozone is a highly reactive form of oxygen produced in the atmosphere by photochemical reactions involving substrates emitted from automobile engines. Outdoor air concentrations as high as 0.4 parts per million (ppm) occur. The respiratory tract extracts about 90% of inhaled ozone. From the chemical reactivity of ozone, it is expected to attack organic molecules located on or near the respiratory surfaces. The airways are covered with a cohesive layer of epithelial cells that forms the boundary between the external environment and the respiratory tissues. One important role of this epithelial layer is its barrier function. Airborne particles that deposit (and dissolve) in the airway surface liquid are not readily absorbed, and soluble tissue components are excluded from the surface liquid. The epithelium also controls the volume and composition of the surface liquid. One important process in this regard is the absorption and secretion of ions and water. We have studied the effects of inhalation of ozone on the barrier function (permeability to dissolved molecules) and the ion transport activity of epithelium using both in vivo and in vitro techniques. All our experiments were performed with male Hartley strain guinea pigs. Conscious, unrestrained animals were exposed to a concentration of ozone of 1 ppm for three hours in controlled environmental chambers in the Health Effects Research Laboratory, U.S. Environmental Protection Agency (EPA), Research Triangle Park, NC. Such exposures caused a marked increase in the rate of appearance in blood of various water-soluble compounds instilled onto the surface of the trachea, indicating increased permeability of the airway epithelium. This interpretation was supported by electron microscopy, which showed that the tracer molecule horseradish peroxidase was present in the intercellular spaces of tracheal epithelium from ozone-exposed, but not air-exposed (control), animals. However, when the tracheas were excised after ozone exposure and mounted in a tissue bath before measurement of permeability, no increase was found. We suggest that the effect of ozone inhalation on airway permeability requires the action of mediators that are washed out in the in vitro situation. When we exposed animals to 1 ppm for 3 hours daily, we found that the increased permeability in vivo was no longer demonstrable after the fourth exposure. The mechanisms for this type of "adaptation" are not known. The phenomenon recalls the response of human subjects to repeated daily ozone exposures. Ozone exposure caused a sharp increase in active ion transport by tracheal epithelium.(ABSTRACT TRUNCATED AT 400 WORDS)

Structural crosslinking of lung connective tissue collagen in the blotchy mouse

Male mice with the sex-linked mutation Blotchy (Blo) have a defect in copper metabolism which results in deficient activity of a number of copper-containing enzymes. Inbred Blo/y mice spontaneously develop lung abnormalities which resemble emphysema and often die of ruptured aortic aneurysm. Lung, tail tendon, and tibial bone collagens from inbred Blo/y and their normal (+/y) litter mates were reduced with standardized [3H]NaBH4, acid and alkaline hydrolyzed, and chromatographed in order to quantify the aldehydic crosslink precursors, and the labile reducible and nonreducible stable mature covalent intermolecular crosslinks. Reducible lung collagen crosslinks were markedly (60%) decreased in the Blo/y mice and few, if any, mature nonreducible crosslinks were present. Total aldehydes were also decreased (65%) when Blo/y was compared to +/y. In tail tendon and bone, collagen crosslinks were decreased by only 28% and 15%, respectively. Selectively severe lack of activity of the copper-dependent enzyme level oxidase in lung with only partial lack in tendon and bone could account for the results obtained. Alternatively, insufficient reducible crosslinks, coupled with increased collagen turnover in the lung could prevent formation of the more mature stable crosslinks required to provide a proper connective tissue framework for the Blo/y lung.

A quantitative study of the development of interalveolar pores in the postnatal mouse

Quantitative analysis of regional interalveolar pore development in the lungs of C3Hf/He mice was performed using scanning electron microscopy. Lungs of male mice ages 7, 10, 14, 21, 28, and 56 days were studied following intratracheal fixation. Interalveolar pores were counted in subpleural, midzonal, and peribronchiolar regions. Interalveolar pores were rarely observed in mice ages 7, 10, and 14 days but appeared abruptly at age 21 days throughout the lung. The number of interalveolar pores increased 2-3 fold from ages 21 to 56 days. By age 28 days and thereafter interalveolar pores were more numerous in subpleural alveoli than in midzonal or peribronchiolar alveoli. We conclude that interalveolar pores appear diffusely in the lungs of mice during the third postnatal week and that regional differences in the number of interalveolar pores are established by age 28 days.

Bilateral trunkal vagotomy (BTV) regarded as a pathogenic process. An experimental study

Experimentally, bilateral trunkal vagotomy (BTV) generated some early acute modifications represented during the first 14 days by blood stasis, partial thrombosis, inflammatory infiltrates and necrobiosis of the gastric mucosa. The vascular lesions are the first to occur, the tissular ones being secondary. Later on, two and three months after surgery, chronic inflammation and metaplasia of the intestinal type have been detected as well.

Bioelectric properties and ion flow across excised human bronchi

Bioelectric properties and ion transport of excised human segmental/subsegmental bronchi were measured in specimens from 40 patients. Transepithelial electric potential difference (PD), short-circuit current (Isc), and conductance (G), averaged 5.8 mV (lumen negative), 51 microA X cm-2, and 9 mS X cm-2, respectively. Na+ was absorbed from lumen to interstitium under open- and short-circuit conditions. Cl- flows were symmetrical under short-circuit conditions. Isc was abolished by 10(-4) M ouabain. Amiloride inhibited Isc (the concentration necessary to achieve 50% of the maximal effect = 7 X 10(-7) M) and abolished net Na+ transport. PD and Isc were not reduced to zero by amiloride because a net Cl- secretion was induced that reflected a reduction in Cl- flow in the absorptive direction (Jm----sCl-). Acetylcholine (10(-4) M) induced an electrically silent, matched flow of Na+ (1.7 mueq X cm-1 X h-1) and Cl- (1.9 mueq X cm-12 X h-1) toward the lumen. This response was blocked by atropine. Phenylephrine (10(-5) M) did not affect bioelectric properties or unidirectional ion flows, whereas isoproterenol (10(-5) M) induced a small increase in Isc (10%) without changing net ion flows significantly. We conclude that 1) Na+ absorption is the major active ion transport across excised human bronchi, 2) Na+ absorption is both amiloride and ouabain sensitive, 3) Cl- secretion can be induced by inhibition of the entry of luminal Na+ into the epithelia, and 4) cholinergic more than adrenergic agents modulate basal ion flow, probably by affecting gland output.

Effect of allergic bronchoconstriction on airways epithelial permeability to large polar solutes in the guinea pig

The effect of allergic bronchoconstriction on the permeability of the airway mucosa to large hydrophilic polar solutes was investigated in the guinea pig. After specific antigen (ovalbumin) challenge, there was a significant increase in the plasma levels of horseradish peroxidase (HRP) (molecular weight, approximately 40,000 daltons), 3H-dextran (approximately 10,000 daltons), and 14C-mannitol (approximately 182 daltons) compared with that in control animals aerosol-challenged with a nonspecific protein, lactoglobulin. The morphologic correlates of this enhanced transepithelial permeability after ovalbumin challenge appeared to be (1) increased HRP penetration of the epithelial tight junctions (p less than 0.001), and (2) increased mucus discharge from surface lining goblet cells. We conclude that antigen-induced bronchoconstriction leads to an increase in tracheobronchial permeability to macromolecules, and this effect is likely to be mediated by an increased paracellular as well as transcellular vesicular movement of large polar solutes across the airway epithelial barrier.

Morphologic and phenotypic analysis of an outcross line of blotchy mouse

Blotchy is an X-linked recessive mutation at the "Mottled" locus in the mouse. The affected blotchy male (Blo/Y) mouse from an inbred genetic background demonstrates morphologic and physiologic abnormalities consistent with emphysema in adult life. Breeding of Blo/Y mice has been difficult because the inbred Blo/Y males are sterile. We report the successful development of a line of outbred Blo/Y male and Blo/Blo female nice by the controlled outcross mating of the inbred heterozygous Blo/+ female with the Argonne hybrid B6CF1 male mouse. The subsequent outcross Blo/Y progeny breed vigorously with the outcrossed Blo/+ female. The lungs of the outbred Blo/Blo female and inbred Blo/Y male mice demonstrate mild to moderate panacinar emphysema with a significant decrease in internal surface area (p less than 0.005) and an increase in mean linear intercept (p less than 0.005). In contrast, the lungs of the outbred Blo/Y is structurally normal. Despite the absence of emphysema-like changes in the outbred Blo/Y males, there were phenotypic features that suggest inherited abnormalities in connective tissue proteins including 1) high incidence of aortitis leading to premature death from aneurysmal rupture, and 2) significant decrease in the morphometrically determined parenchymal elastic fiber length in the lung (p less than 0.01). The outbred blotchy strain may be a useful experimental animal model in determining the pathogenesis of emphysema.

[Microvascularization of the liver in vagotomy]

Sub-diaphragmatic truncal vagotomy produces early and late changes in the microvascular network of the liver. Bilateral sub-diaphragmatic truncal vagotomy was performed experimentally in the dog. After 7 days, 60 days and 2 years, the animals were subjected to laparotomy under general anaesthetic and China ink was injected into the aorta above the coeliac trunk. Samples were then taken from the hepatic parenchyma to be examined under the photomicroscope. The following early modifications were observed: absence of the injection in the central and intermediary zones of the lobe, stasis in the centro-lobular vein. These modifications are also present at 60 days. After 2 years, there is an improvement in the hepatic microcirculation, but modifications of micro-irrigation are still present.

Morphological aspects of the rat kidney preserved by cold storage. I. Glomerular morphometric changes

The absolute density of glomeruli in the microscopic field was determined in the rat kidney preserved by cold storage for 24, 48, 72 and 96 hrs in two different media: Sacks (hyperosmolar electrolytic solution of intracellular type) and Plasmagel (gelatin solution 4%). Progressive, statistically significant (p less than 0.01) decrease of glomerular density at 24 and 48 hrs was followed by return to initial values at 96 hrs. Decrease of the glomerular density was greater with Plasmagel.

Experimental study on the effects of +Gz. Acceleration under gestational conditions. I. Ultrastructural myocardial lesions

In the course of a complex experimental study concerning the effects of highly positive acceleration on gestation and development of the neonate, investigations were carried out of ultrastuctural myocardial lesions in the pregnant rat exposed to prolonged gravitational stress (+ 2G). The experimental animals presented various disseminated and partly irreversible myocardial lesions whose pathogeny is discussed.

The effect of pilocarpine on vesicular uptake and transport of horseradish peroxidase by the guinea pig tracheal epithelium

The quantitative relationship between goblet cell number and airway transepithelial permeability to horseradish peroxidase (HRP) (molecular weight, approximately 40,000 daltons) was examined in the guinea pig. In animals administered 12 daily successive doses of 2.5 mg pilocarpine intraperitoneally, an increase in goblet cell population in the trachea correlated with higher plasma HRP concentrations of all 4 sampling times after intratracheal instillation of 1 mg HRP. Guinea pigs administered a single dose of pilocarpine and studied 1 h later showed a significantly higher plasma HRP concentration at 10 and at 15 min (p less than 0.025) as compared with saline control animals. The morphologic correlates of this enhanced early permeability to HRP after a single dose of pilocarpine appeared to be increased vesicular uptake and accelerated transit across the goblet cells. Our data suggest that pinocytotic vesicular uptake and transport of exogenous proteins in the secretory epithelial cells of the airways may be an important pathway for movement of large polar solutes across the epithelial barrier.

The effects of small doses of oligopeptide elastase inhibitors on elastase-induced emphysema in hamsters: a dose-response study

Our previous studies have indicated that the synthetic elastase inhibitor N-acetyl-L-alanyl-L-alanyl-L-prolyl-L-alanyl chloromethylketone (AAPACK) administered intraperitoneally in divided doses totaling 19 mg, prior to and after a single intratracheal injection of elastase, substantially inhibited the development of experimental emphysema. The present studies evaluated the effects of 1.1, 4.1 and 8.0 mg AAPACK administered in divided doses 10 min prior to and 10, 30, and 50 min after a single intratracheal dose of elastase. The development of emphysema was essentially eliminated by 4.1 and 8.0 mg of AAPACK and markedly diminished with 1.1 mg AAPACK. The AAPACK was excreted rapidly in the urine at 30 to 60 min after its administration. Elastase inhibitory capacity (EIC) in urine was elevated to 14 times that in serum at the corresponding collection times. The plasma elastase inhibitory capacity was only slightly increased after administration of AAPACK and was not a sensitive indicator of elastase inhibition in the plasma.

Effects of oligopeptide chloromethylketone administered after elastase: renal toxicity and lack of prevention of experimental emphysema

The effectiveness of N-acetyl-L-alanyl-L-alanyl-L-prolyl-L-alanine chloromethylketone (AAPACK) in preventing the development of experimental emphysema in hamsters, when administered 60 min after exposure to elastase, was studied. When 19 mg of AAPACK was injected intraperitoneally in divided doses commencing 60 min after the intratracheal instillation of pancreatic elastase, the development of emphysema was not prevented using morphologic, morphometric, and physiologic means of evaluation. Thirty-eight per cent of hamsters given AAPACK became ill and lost weight. At autopsy, these hamsters had a renal tubular nephropathy and focal interstitial disease. The glomeruli were spared. Five of these hamsters with renal tubular lesions had azotemia. Focal necrosis was observed in the heart of 3 and in the liver of 5 animals with renal lesions. These studies indicated that AAPACK, in the protocol followed where elastase precedes administration of the inhibitor, (1) does not prevent the development of elastase-induced emphysema, and (2) does produce a unique renal tubular nephropathy.

A quantitative study of ciliary injury in the small airways of mice: the effects of nitrogen dioxide

The frequency and types of abnormal cilia prior to and following nitrogen dioxide (NO2) exposure in the small airways of an inbred strain of mice was quantitated by transmission electron microscopy. Age-matched male and female mice were exposed to 20 ppm NO2 for 28 days. In both sexes, exposures to NO2 resulted in a significant increase (P less than 0.01) in abnormal cilia characterized by (1) decreased number of ciliary structures on cell surface, (2) focal swelling of the cytoplasmic matrix of the ciliary shaft, and (3) occasional compound cilium. The basal bodies of the ciliated cells from which atypical cilia arose appeared normal. In mice killed 30 days after termination of NO2 exposure, the ciliary morphology returned to normal and the incidence of abnormal cilia decreased to levels observed in controls. These observations indicate that subacute exposure to NO2 causes injury to the ciliary shaft; these changes are reversible within 30 days following removal from NO2.

Elements of structure and ultrastructure of the blood-thymus barrier in ACTH involuted thymus

The ACTH influence upon the thymus may be a reliable model for stress involution. In this case, the cortical lymphocytic depletion is accompanied by mast cell accumulation and increased caliber of the blood vessels. The blood-thymus barrier which has an active role in involution shows an enriched transport activity of the endothelial cells, great enlargement of the basement membrane, increased macrophage activity within the perivascular space with elevated values of acid phosphatase activity, and thickening of the fibrillar network. The epithelioreticular cells show plenty of vacuoles in their cytoplasm, the mitochondria undergo swelling processes, and their cristae are diminished. The ultrastructural data show that lymphocyte depletion is carried out by macrophage-mediated lymphocytolysis. But by counting the peripheral blood cells an earlier mechanism is revealed; i.e. migration through the enlarged but more permeable blood-thymus barrier. The epithelioreticular cells do not seem to have an active, direct implication in any of the phenomena.

Experimental study of myocardial bridges

Myocardial bridges were reproduced in dogs by transfer of a fragment of the left ventricular wall above the upper portion of the anterior interventricular artery. The viability of this bridge was shown by coronarography, anatomic, histologic and electron microscopic studies, illustrating the vascular patency and the integrity of blood vessels and neighbouring myocardium in the cases postoperatively heparinized. The experimental model efficiency was also proved by ECG examinations revealing ischemic distresses induced by compression of the bridge against the underlying artery.

Lung injury and repair in the blotchy mouse. Effects of nitrogen dioxide inhalation

We studied the reparative process after inhalation exposure to 20 ppm of nitrogen dioxide (NO2) in the lungs of hemizygous blotchy male (Blo/g) and heterozygous blotchy female (Bio/+) mice. Age-matched siblings (C3Hf) without the blotchy gene at X-chromosome locus (+/y) and +/+) served as control animals. After exposure to NO2 for 28 days, there was a marked progression in the extent of emphysema in Blo/y mice associated with a significant decrease of internal surface area (p < 0.05) and an increase in the mean linear intercept (p < 0.005). In contrast, +/y, Blo/+, and +/+ mice showed mild airspace enlargement without decrease in internal surface area after similar exposures. Blo/y mice killed 1 month after cessation of NO2 exposure showed a persistent, mild chronic bronchiolitis that was more frequent and of greater severity than that present in control +/y mice. Alveolar macrophages in the Blo/y mice were larger than those in +/y, +/+, and Blo/+ mice both before and after exposure to NO2. Crystalloid inclusions were observed in the enlarged alveolar macrophages of the Blo/g mice only after exposure to NO2, but were not seen in control animals. These observations indicate that the pattern of lung injury and repair after subacute exposure to 20 ppm of NO2 in the Blo/y mouse differs from that present in age-matched siblings in that inherited abnormalities in alveolar macrophage function may exist in addition to the previously described alterations in connective tissue proteins. Both of these alterations may influence the development of emphysema in the blotchy male mouse.

The effect of nitrogen dioxide on tracheal uptake and transport of horseradish peroxidase in the guinea pig

The effect of 5 and 15 ppm of nitrogen dioxide (NO2) on airway transepithelial permeability to horseradish peroxidase (HRP) (molecular weight, approximately 40,000 daltons) was studied in the guinea pig. Age- and sex-matched guinea pigs (n = 34) were exposed to NO2 for 2 and for 14 days. In the control guinea pigs, 0.05% of the intratracheally instilled dosage HRP was present in the plasma within 10 min, as detected by radioimmunoassay, and increased thereafter at amean rate of 0.0016%/min. After exposure to NO2, there was a significant increase in the rate of plasma HRP accumulation (p < 0.05) with the maximal increase detected in the group exposed to 15 ppm of NO2 for 2 days. The morphologic correlates of increased permeability to HRP appear to be (a) an increase in pinocytotic activity within the hyperplastic globlet cells, and (b) transjunctional transport by leaky tight junctions that was noted only in animals exposed to 15 ppm for 14 days (p < 0.01). Our data suggests that pinocytotic vesicular transport of proteins in the secretory cells of the airway may be an important mechanism for the movement of exogenous nonlipid soluble macromolecules across the epithelial barrier.

Interalveolar pores in mouse lung. Regional distribution and alterations with age

Quantitative analysis of the regional distribution of interalveolar pores in the lungs of BALB/c mice 1 to 28 months of age (n = 25) was performed by scanning electron microscopy. In all the age groups examined, the subpleural and peribronchiolar alveoli had significantly more pores than the midzonal region (p < 0.01). No significant changes were noted in the number of pores per alveolus between 3 and 26 months of age in the midzonal, peribronchiolar, and subpleural alveoli. We concluded that (1) intralevolar pores are regionally distributed in the lungs of BALB/c mice by 3 months of age, and (2) the number of pores do not significantly change with increasing age during the first 26 months.

The effect of the specific elastase inhibitor, alanyl alanyl prolyl alanine chloromethylketone, on elastase-induced emphysema

The chloromethylketone derivative of the tetrapeptide, alanyl alanyl prolyl alanine significantly diminishes the extent of experimental elastase-induced emphysema in hamsters. A total of 19 mg of alanyl alanyl prolyl alanine chloromethylketone was administered intraperitoneally in divided doses before and immediately after intratracheal instillation of a standard dose (4 units) of porcine pancreatic elastase. Morphologic evaluation and measurement of mean linear intercept, internal surface area, and lung volume performed 7, 45, and 120 days after exposure to elastase indicated a marked decrease in the extent of emphysema in the group treated with alanyl alanyl prolyl alanine chloromethylketone compared with the control group. Lung elastin content determined biochemically confirmed the preservation of elastin in the hamsters treated with alanyl alanyl prolyl alanine chloromethylketone. At postmortem examination by light microscopy, no pathologic abnormalities were observed in the organs of hamsters treated with alanyl alanyl prolyl alanine chloromethylketone. These data indicate that alanyl alanyl prolyl alanine chloromethylketone in the doses administered (1) had significant anti-elastase activity in vivo; (2) markedly decreased the extent of elastase-induced emphysema; and (3) produced no adverse toxic effect during the period covered by this study protocol.

Age-related changes in elastic fibers and elastin of lung

The effect of age on the lung elastic tissue of inbred BALB/c mice were studied. Static compliance of excised lungs increased with age. Morphometrically determined total elastic fiber length increased with lung expansion in age- and sex-matched mice (r = 0.83, P smaller than 0.001), indicating an axial extension of elastic fibers. However, total elastic fiber length of aging lungs fixed at a distending pressure of 15 cm H2O showed no significant change despite an age-related increase in lung volume (male, r = 0.96, P smaller than 0.001; female, r = 0.95 P smaller than 0.001). The correlative finding of decreased elastin content (r = -0.87, P smaller than 0.001) indicates that there is a loss of elastic fibers in the aging lung. It is suggested that the absence of pseudoelastin fibers, as demonstrated by histochemical techniques, accounts for the observed differences in elastin content of aging human and mouse lungs.

Effect of histamine and methacholine on guinea pig tracheal permeability to HRP

The effects of histamine, methacholine, and ether on the permeability of the respiratory mucosa to macromolecules were investigated employing a radioimmunoassay and histochemical techniques to monitor movement of horseradish peroxidase (HRP) from airway lumen to blood. We found that 0.08% of the dose of HRP instilled into guinea pig tracheas was present in the blood volume at 10 min, and plasma HRP levels increased at a rate of 0.0036% instilled dose/min thereafter. After inhalation challenge, significant increases in plasma rates of accumulation of HRP were recorded for the histamine, methacholine, and ether groups, whereas no change in rate was noted for the control (Tyrode's) group. Electron micrographs of tracheal sections showed HRP penetration into the intercellular spaces of the epithelium after histamine, methacoline, or ether exposure but no penetration in the Tyrode's group. We conclude that, like ether, histamine and methacholine increase tracheobronchial permeability and this effect is most likely mediated by a functional change in the epithelial tight junction.

Structure and function of small airways in health and disease

During the last two decades, great strides have been made in our understanding of the functional aspects of airflow in the periphery of the lung. It seems that the small airways are the important site of obstruction in a variety of chronic respiratory disorders associated with airflow obstruction. This review deals with the anatomic and functional aspects of small airways in normal and diseased lungs. In particular, the basis of obstruction or narrowing that is not dependent on intrinsic airway lesion is reviewed. The variety of pathologic changes in small airways observed in these diseases are outlined along with physiologic tests that are currently used to detect dysfunction at a stage long before they produce symptoms or alter standard tests of lung function.

Pulmonary resection

Seventy-seven patients who had elective pulmonary resections were enrolled in a prospective double-blind study to assess the role of prophylactic antibiotics in preventing postoperative infections. Criteria for infection were strictly defined. A five-day course of a cephalosporin (2 gm/day in divided doses) was compared to an identical placebo. There were 17 infections in the 34 patients in the placebo group (50%), compared to only eight infections in the 43 patients in the antibiotic group (19%) (P = .005). When infections unrelated to thoracotomy and minor infections were excluded, the advantage of prophylactic antibiotics proved even more evident. Fourteen thoracic infections occurred in the placebo group (41%) compared to only two thoracic infections (4.7%) in the antibiotic group (P = .0002). No relationship of infection rate to the extent of pulmonary resection was found. A history of smoking, the presence or absence of chronic bronchitis, spirometric abnormalities, and obesity were all analyzed; none was related to the development of infection. We conclude that the routine use of perioperative antibiotics is indicated to prevent postoperative infections in pulmonary resection.