Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Secretory Component”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,297 records · Page 72Linked to original sources
PubMed1995

Isolation and characterization of a 30-kDa endometrial glycoprotein synthesized during the estrous cycle and early pregnancy of the pig.

Endometrial polypeptide synthesis, which is regulated through ovarian steroid secretion and steroid production by the developing conceptus, not only provides the necessary secretory components vital to conceptus development but also presents the adhesive changes in the epithelial surface essential for conceptus attachment. In the present study, a 30-kDa, basic endometrial glycoprotein (pGP30) was isolated and characterized during the estrous cycle and early pregnancy of the pig. Uterine flushings and endometrial culture media were obtained from gilts on Days 0, 5, 10, 12, 15, and 18 of the estrous cycle and Days 10, 12, 15, and 18 of pregnancy. A polyclonal antibody was generated to pGP30 after isolation of medium from Day 15 pregnant endometrial cultures separated by gel filtration and PAGE. Western blot analysis indicated that the antiserum reacted with isoforms of pGP30 and cross-reacted with a 90-kDa component in serum that was not removed after cleavage of the oligosaccharide chains from the 90-kDa glycoprotein. Antiserum did not detect a 30-kDa band in media from cultures of kidney, fat, heart, muscle, liver, or serum; however, heart and muscle did contain bands of different molecular masses that cross-reacted with the antiserum. Multiple bands of higher molecular mass (35-40 kDa) were detected in the endometrial cultures from gilts on Days 0 through 10 of the estrous cycle. Treatment of ovariectomized gilts with estradiol-17 beta stimulated a similar response. During the mid- to late luteal phase of the estrous cycle (Days 12-18), the 30-kDa band as well as an additional 32-kDa band was present on Western blots. Administration of progesterone for 14 days stimulated the synthesis of both the 30- and 32-kDa products in ovariectomized gilts. However, only the pGP30 was detected on Days 12-18 of pregnancy. Immunocytochemical localization with antiserum to pGP30 indicated that the glycoprotein is present in the endometrial epithelium, with the surface epithelium demonstrating the strongest reaction product. Discrete changes in staining and cellular localization were observed during the early stages of the estrous cycle (Days 0-5) and the midluteal (Day 10) phase. A similar response was achieved with administration of steroids to ovariectomized gilts. Data indicate that discrete changes in epithelial synthesis of the endometrial glycoprotein occur at the time of conceptus trophoblastic elongation and placental attachment in the pig.

Animals↗
PubMed1997

Estrogen stimulation of P450 cholesterol side-chain cleavage activity in cultures of human placental syncytiotrophoblasts.

The present study determined whether estrogen has a role in regulating the P450 cholesterol side-chain cleavage enzyme (P450scc) and/or de novo/deesterification cholesterol pathways involved in progesterone biosynthesis within human syncytiotrophoblasts. Human placental syncytiotrophoblasts were cultured for 48 h with estradiol, and P450scc activity was determined by the formation of progesterone from 25-hydroxycholesterol. Estradiol at 10(-7) or 10(-6) M and 25-hydroxycholesterol increased mean (+/- SE) progesterone production by syncytiotrophoblasts (ng/0.5 x 10(6) cells) to a value (19.2 +/- 1.1) that was 104% (p < 0.001) higher than that of the untreated controls (9.4 +/- 0.8) and 52% higher (p < 0.001) than with 25-hydroxycholesterol alone (12.6 +/- 0.9). The stimulation of progesterone secretion apparently was not the result of a change in progesterone metabolism to its principal metabolite, because 20alpha-hydroxypregn-4-en-3-one represented a minor secretory component (0.7-1.7 ng/0.5 x 10(6) cells) under these conditions, and levels were not substantially altered by estrogen. In contrast to the stimulatory effect of estradiol on P450scc activity, estrogen did not alter either the P450scc mRNA levels or the activities of 3-hydroxy-3-methylglutaryl coenzyme-A reductase and cholesterol ester hydrolase-rate-limiting enzymes for the de novo and deesterification pathways, respectively, for cholesterol formation in syncytiotrophoblasts in culture. Collectively, these results indicate that estrogen regulates the P450scc component of the progesterone biosynthetic pathway, which we suggest signals functional/biochemical differentiation of syncytiotrophoblasts during primate pregnancy.

Cholesterol Side-Chain Cleavage Enzyme↗
PubMed1997

Generation of papillomavirus-immortalized cell lines from normal human ectocervical, endocervical, and vaginal epithelium that maintain expression of tissue-specific differentiation proteins.

We have established and characterized three cell lines from normal human vaginal, ectocervical, and endocervical epithelia immortalized by expression of human papillomavirus 16/E6E7. The lines (VK2/E6E7, Ect1/E6E7, and End1/E6E7) displayed distinctive morphologies at the level of light microscopy when cultured in calcium-supplemented (0.4 mM) keratinocyte serum-free medium and maintained a stable phenotype after more than 1 yr of continuous passage. They were compared to primary cell cultures and epithelial cells in sections of the respective native tissues for expression of epithelial differentiation proteins. All cell lines expressed cytokeratin (CK) 8, CK18, and CK19, and some cells in all three cell lines expressed CK16, involucrin, and the secretory component of the polymeric immunoglobulin receptor. The vaginal and ectocervical cell lines expressed CK10 and CK13, whereas the endocervical line did not. With the exception of CK8 and CK18 expression, the morphological and immunocytochemical characteristics of the immortalized lines closely resembled those of their respective tissues of origin and primary cultures, and all differed significantly from the HeLa cervical adenocarcinoma cell line. These new cell lines may provide the basis for valid, reproducible in vitro models for studies on cervicovaginal physiology and infections and for testing pharmacological agents for intravaginal application.

Antigens, Differentiation↗
PubMed1997

Polymeric immunoglobulin A receptor in the rodent female reproductive tract: influence of estradiol in the vagina and differential expression of messenger ribonucleic acid during estrous cycle.

Previously we have shown that estradiol and progesterone regulate the levels of secretory component, the external domain of polymeric immunoglobin A (IgA) receptor responsible for transporting IgA from tissues into secretions, at both the mRNA and protein levels in the rodent uterus. In the present study, experiments were designed to determine whether polymeric immunoglobulin receptor (pIgR) is synthesized locally in the vagina and whether it is under the control of estradiol and progesterone. Polymeric IgR message corresponding in size to that previously reported in the liver and uterus was detected by Northern blot analysis of total RNA from the vagina. Levels of pIgR mRNA and pIgR in the vagina were found to vary with the stage of the cycle. Polymeric IgR mRNA levels were elevated at diestrus, reduced at estrus, and undetectable at proestrus. Immunohistochemical analysis of pIgR in the vagina indicated that the expression of protein correlated with the mRNA levels. When ovariectomized rats were treated with estradiol, progesterone, or a combination of the two for 3 days, pIgR mRNA levels were significantly reduced in estradiol-treated animals relative to saline-treated controls. No significant changes were observed in the pIgR mRNA levels of animals treated with progesterone alone or with a combination of estradiol and progesterone. Polymeric IgR expression analyzed by immunohistochemical staining correlated well with variations in mRNA levels seen following hormone treatment. In situ hybridization localized pIgR in uterine and vaginal epithelial cells. In the uterus, pIgR message was abundant in luminal and glandular epithelial cells at estrus and low at diestrus. In contrast, expression of pIgR mRNA was pronounced in vaginal epithelial cells at diestrus, while very little message could be localized in the epithelium at estrus. These findings demonstrate that pIgR is synthesized locally in the uterus and vagina and is under tissue-specific hormone regulation.

Animals↗
PubMedDate not supplied

Increase of IgA in pharyngeal washings from patients with IgA nephropathy.

The levels of IgA and total proteins in pharyngeal washings were examined in patients with IgA nephropathy and other glomerular diseases in order to determine whether secretory IgA, IgA1 and IgA2 were increased in these patients. Thirty patients with IgA nephropathy, 21 patients with other glomerular diseases and 15 healthy adults were examined. The levels of IgA were quantitated by radial immunodiffusion and laser nephelometry. The levels of total proteins in pharyngeal washings were quantitated by Tonein-TP. It was demonstrated that the levels of IgA in pharyngeal washings were significantly increased in patients with IgA nephropathy compared to those with other glomerular diseases and healthy adults. The levels of total proteins in pharyngeal washings were increased in patients with IgA nephropathy, and the ratio of IgA and total proteins in the washings from patients with IgA nephropathy was not significantly different from those healthy adults. There was a significant correlation between the levels of IgA in pharyngeal washings and those of IgA in sera from patients with IgA nephropathy. The IgA observed in pharyngeal washings contained secretory components, IgA1 and IgA2, in patients with IgA nephropathy. It is suggested that the increase of IgA in the pharyngeal washings in parallel with the increase of total proteins might be associated with local inflammation.

Humans↗
PubMed1981

Crypt cell carcinoma of the appendix (so-called adenocarcinoid tumor).

A series of 16 carcinoid tumors of the appendix, including four examples of so-called adenocarcinoid tumors, has been studied immunohistochemically for the presence of lysozyme, secretory component (SC) and IgA, within tumor cells. Stains for mucin, Paneth cells, and APUD cells were also performed. Of the conventional carcinoid tumors, eight showed focal tubule formation with production of PAS-positive material. In contrast to conventional carcinoids, including those showing tubule formation, adenocarcinoids contained few APUD cells and showed positive staining of tumor cells for lysozyme, SC, and IgA. Paneth cells, staining positively for lysozyme, were present in two cases and mucin-containing Paneth cells were observed. A parallel study of normal small intestinal mucosa demonstrated a population of lysozyme containing goblet cells within the crypts. It is suggested that so-called adenocarcinoid tumors are not derived from APUD cells but from lysozyme-producing cells of the type normally present in small intestinal crypts.

Adenocarcinoma↗
PubMed1995

Chronic gastritis: its clinical and physiopathological meaning.

Chronic gastritis (CG) is the chronic inflammation of gastric mucosa associated with varying degrees of damage of superficial and glandular epithelia. The causes of CG are exogenous (mainly Helicobacter pylori) and endogenous. The process is concluded by atrophy of parenchyma. CG is associated with dyspepsia in approximately 50% of cases, but frequently with gastric and duodenal ulcer. The role of chronic atrophic gastritis (AG) is relevant in development of cancer or of other tumors like carcinoids and polyps. The specific secretive cells of the glandular parenchyma and of the superficial epithelium reveal a good correlation with secretory component behavior, but they are only partially influenced by H. pylori. It emerges that CG is an anatomic-functional condition. The cytofunctional profile in AG causes achlorhydria and therefore chronic luminal alkalosis. This condition favors intestinal metaplasia (IM) and important intraluminal troubles. Finally, nutritional deficiencies or H. pylori seem to interfere with the intragastric metabolism and therefore play a relevant role in the rise of IM.

Atrophy↗
PubMedDate not supplied

Coprocytobiology: on the nature of cellular elements from stools in the pathophysiology of colonic disease.

The gastrointestinal epithelium is known to undergo constant and rapid renewal resulting in millions of cells being shed into the fecal stream every day. The conventional wisdom was that these cells disintegrate upon exfoliation and will not survive the transit through the intestinal tract. In 1990, we (P.N.) made the discovery that a significant number of these cells remain intact and viable and that they can be isolated. The implications of this important discovery became apparent when we demonstrated that these cells are exclusively of colonic origin, are anatomically representative of the entire colon, and can be used for clinical investigations of disease processes. The term coprocytobiology (CCB) was coined to encompass the broad range of applications of this new technology. The somatic cell sampling and recovery (SCSR) process involves the isolation of exfoliated colonocytes from a small sample of stool ( approximately 1 g) collected and transported in a unique medium at ambient temperature, providing cells for the detection of a number of biomarkers of disease propensity. These exfoliated colonocytes express cytokeratins indicating epithelial lineage as well as colon-specific antigen. Over the years, the study of exfoliated colonocytes has provided striking new insights into the biology of colon cancer and inflammatory bowel disease, including detection of p53 gene mutations, reverse transcriptase polymerase chain reaction amplification, and identification of CD44 splice variants, neoplasia-associated specific binding of plant lectins, and expression of COX-2, the inducible form of cyclooxygenase. The functional diversity of cells isolated by SCSR is revealed by the demonstration of cell surface markers such as secretory component, IgA, and IgG on the one hand and the amplification and cloning of the human insulin receptor and the expression of the multidrug resistance gene mdr-1 on the other hand. This review portrays the immense potential of CCB as a powerful tool for investigating the pathophysiology of disease, identifying genetic variants in pharmacogenetics, assessment of mucosal immunity, and several other applications that use somatic cells.

Antigens, Neoplasm↗
PubMed1985

Intestinal and serum immune response to a naturally acquired rotavirus gastroenteritis in children.

Seventeen children (mean age: 2.0 years, range: 36 days-8 years) hospitalized with acute gastroenteritis were investigated. Thirteen children had a rotavirus infection while four did not. Rotavirus serum IgA as well as ScIg, i.e., antirotavirus immunoglobulin containing secretory component, increased rapidly after rotavirus infection. While rotavirus IgA persisted in serum for at least 6 months, rotavirus ScIg disappeared from serum in less than 4 months. Rotavirus IgG could be detected in serum during the early stage of the infection and was still high after 6 months. The patients with nonrotavirus acute gastroenteritis did not show any of the above-mentioned serological hallmarks of those with rotavirus infection. The amounts of rotavirus ScIg found in serum about 1 week after the infection correlated to the amounts of rotavirus ScIg in duodenal fluid. Six months after the infection, rotavirus IgA was found in the feces of the majority of the patients while rotavirus ScIg could be detected only in one patient. The amounts of rotavirus IgA in sera and intestinal secretions showed identical patterns in the acute phase of the disease as well as after recovery. The same applied to rotavirus ScIg. These findings could be useful in future evaluations of vaccines and immunity against rotavirus infections.

Antibody Formation↗
PubMed1985

Rotavirus antibodies in the mother and her breast-fed infant.

The transfer of rotavirus antibodies from 25 healthy mothers to their breast-fed infants was investigated during the period of lactation (mean, 3.9 months; range, 1-9 months). Furthermore, the destiny of these antibodies in the infants' gastrointestinal tract and serum was examined. Rotavirus-specific immunoglobulins were analyzed by the ELISA (enzyme-linked immunosorbent assay) technique. All the mothers had rotavirus IgA and IgG in serum. About 80% of the mothers had low concentrations of rotavirus ScIg (i.e., antirotavirus immunoglobulin containing secretory component) in serum at the beginning of the lactation period declining to about 45% at the end of the period. From a few days after delivery to about 2 weeks later, the concentrations of rotavirus IgA and ScIg in milk declined. Thereafter, they remained unchanged. There was a positive correlation among the concentrations of rotavirus IgA in serum and rotavirus IgA as well as ScIg in milk. Rotavirus IgG in the infants' serum correlated with that of the mothers. Few samples of the infants' duodenal fluid contained rotavirus IgA or ScIg. On the other hand, about 80% of the infants' fecal samples contained rotavirus ScIg and IgA. Rotavirus IgA and ScIg disappeared from the infants' feces after cessation of lactation. Hence, it may be concluded that infants receive rotavirus IgG through the placenta, and rotavirus ScIg and IgA in constant amounts via milk throughout the period of lactation. The small intestine is flushed with rotavirus ScIg and IgA at each breast-meal, and these antibodies survive proteolysis in the gut. A possible protectional effect of rotavirus ScIg or IgA requires frequent breast-meals, and the effect is limited to the period of lactation.

Adult↗
PubMed1990

Transport of water and electrolytes by rotavirus-infected mouse intestine: a time course study.

The movement of water and transport of Na+ and Cl- by mid-small intestine (M-SI) of rotavirus-infected neonatal mice was investigated by an in vitro perfusion technique. The concentrations of Na+, K+, and Cl- in the luminal contents of upper, middle, and lower small intestine and colon of infected mice were determined by flame photometry (Na+, K+) and an ion selective microelectrode (Cl-). In M-SI, maximal disturbance of water transport occurred at 72 h postinfection (PI): Infected tissue exhibited net water secretion. Water transport was also impaired at 144 h PI. Net secretion of Cl- occurred at 72 h PI, with some evidence of a second phase of reduced magnitude at 120-144 h PI. The magnitude and statistical significance of changes in Na+ transport were both less than those for Cl-, but the pattern of change was similar to that for Cl-. Luminal concentrations of Na+ were elevated between 48 and 144 h PI in the small intestine; this was particularly so in distal regions. Luminal Cl- concentration was maximally elevated to a considerable degree at 72 h PI and remained high at 96 h PI throughout the small intestine; thereafter, Cl- concentration returned to near normal. K+ concentration was unchanged in the small intestinal lumen; in the colon, however, K+ concentrations were depressed 72-168 h PI. In the light of previous data from this laboratory, the present data are interpreted as evidence for a secretory component in rotavirus-induced diarrhea.

Animals↗
PubMed1989

Patterns of pancreatic secretion in the anaesthetised guinea pig following stimulation with secretin, cholecystokinin octapeptide, or bombesin.

The guinea pig is frequently used for studies of the cellular mechanisms of pancreatic secretion. Despite this, little is known about the control of pancreatic secretion in this species. To remedy this omission, we have studied the effects of secretin, cholecystokinin (CCK) octapeptide, and bombesin on the secretion of fluid, electrolytes, and amylase in the anaesthetised guinea pig. While the actions of secretin were similar to those in other species, the actions of CCK were not. As well as stimulating amylase release, CCK evoked a marked fluid secretion whose electrolyte composition differed little from that evoked by secretin. Bombesin had actions similar to those of CCK. It is suggested that this fluid secretion is derived from pancreatic acini. Whether a similar secretory component exists in other species (including humans), albeit as a minor component, needs to be determined.

Amylases↗
PubMed2000

Modified wick method using Weck-Cel sponges for collection of human rectal secretions and analysis of mucosal HIV antibody.

Weck-Cel sponges were examined for suitability as an absorbent material for nontraumatic collection of rectal secretions in humans. Sponges were tested in vitro and determined by quantitative enzyme-linked immunosorbent assay (ELISA) to be capable of releasing 100% of absorbed albumin and all immunoglobulin subtypes after treatment with detergent-supplemented buffer. Protein composition in rectal secretions collected from normal women with dry sponges (DS) or with sponges previously softened by moistening with saline (MS) was subsequently compared. DS secretions showed evidence of contamination with blood and interstitial fluid-derived albumin, immunoglobulin G (IgG), and monomeric IgA. MS secretions appeared to represent local mucosal secretions more accurately because they contained negligible blood, a greater percentage of secretory IgA within the total IgA, and both lower albumin/IgG ratios and more dramatic alterations in IgG subclass distribution compared with corresponding serum. Anti-HIV IgG, IgM, IgA, and antibodies with secretory component could be demonstrated by ELISA in rectal secretions collected with moist sponges from 8 of 8, 1 of 8, 5 of 8, and 3 of 8 HIV-infected women, respectively. The data show that Weck-Cel sponges, if premoistened, can be used to collect rectal fluids nontraumatically and to obtain quantitative information about concentrations of immunoglobulins and specific antibodies on rectal mucosal surfaces.

Adult↗
PubMed1993

Pathological changes in the rabbit ileal loop model caused by Campylobacter jejuni from human colitis.

Four strains of Campylobacter jejuni isolated from children with inflammatory diarrhoea were assayed in the rabbit ileal loop model of infectious diarrhoea. All caused inflammatory reactions with severe macroscopic and microscopic damage in infected rabbit ileal tissue similar to that observed in the patients by endoscopy and histological analysis of colonic biopsies. Haemoglobin and other proteins were observed in loop fluids, consistent with leakage of serum from damaged mucosa. Loop fluids also contained significant bicarbonate concentrations, indicative of an active secretory component similar to that in control loops inoculated with cholera toxin. However, although three of the four clinical strains produced small amounts of a protein immunologically related to cholera toxin in vitro, none such was detected in either tissues or fluids of infected ileal loops. We propose instead that host-derived mediators of secretion may be important in pathogenesis. A mutant strain of C. jejuni with impaired motility, obtained from the National Collection of Type Cultures, did not induce tissue damage or fluid secretion in rabbit ileal loops.

Animals↗
PubMed1994

Intestinal B cell defects in common variable immunodeficiency.

The humoral immune system of the small intestine of 17 patients with common variable immunodeficiency (CVID) was studied by immunohistology using antibodies specific for IgA1,2, IgM, IgG1-4, the J chain and the secretory component (SC). IgA1,2+, IgG2+ and IgM+ lamina propria B cells were totally lacking in 65% (11/17), 41% (7/17) and 18% (3/17) of CVID patients, respectively. One patient exhibited an isolated IgA1 subclass deficiency. The proportion of plasma cells in conventionally stained histological sections of the same intestinal biopsies showed a close correlation with the numbers of IgA+ and IgM+ cells. Considerable numbers of J chain-synthesizing cells were present in all patients with CVID, indicating the presence of early B cells unable to differentiate into immunoglobulin-producing plasma cells. Most of the patients with intestinal IgA and/or IgM defects strongly expressed the SC in their enterocytes, suggesting an immunoglobulin-independent regulation of the SC. Clinically, only CVID patients with intestinal IgA defects developed intestinal infections with Giardia lamblia, Campylobacter jejuni or Candida albicans. The outcome of in vitro immunoglobulin synthesis assays with peripheral blood lymphocytes did not predict the presence or absence of the respective isotype-producing B cells in the intestinal lamina propria. Thus, immunohistological examinations of intestinal biopsies are required to determine the extent of mucosal immunodeficiency in CVID patients.

Adolescent↗
PubMed1984

Adenocarcinoma of the endometrium with glassy-cell features--immunohistochemical observations.

A case of adenocarcinoma of the endometrium with glassy-cell features is reported and histochemical and immunohistochemical data are provided together with a review of the relevant literature. The microscopical features of glassy-cell carcinoma appear to be highly characteristic and diagnostic. The tumour is considered to be a distinctive and poorly differentiated type of adenosquamous carcinoma originating in the cervix or the endometrium. We studied the expression of several differentiating characteristics and detected the presence of secretory component and lysozyme in some tumour cells, whereas keratin and prekeratin were consistently absent. Since in normal uterine mucosa immunoreactivity for lysozyme is restricted to endocervical and isthmic epithelium, the presence of this antigen in the tumour would favour an endocervical or isthmic origin of the tumour cells. Furthermore our results suggest that this peculiar type of tumour is not poorly differentiated and that the assertion that glassy-cell carcinoma is a variant of adenosquamous carcinoma is open to doubt.

Adenocarcinoma↗
PubMed1990

Solitary and synchronous adenomas of the colon and rectum: comparison of malignancy parameters.

The histological, mucin histochemical and immunohistochemical features were evaluated of 74 solitary and 73 synchronous colorectal adenomas which were endoscopically removed from 124 patients. Of the patients, 60% had a single adenoma, whereas 40% had at least two adenomas in their colorectum. Comparing the incidence of synchronous adenomas in both sexes revealed a statistically significant higher incidence (P less than 0.005) in males. The localization of the solitary and synchronous adenomas in the large bowel was similar. Moreover, parameters of malignant change within the adenomas (size, predominant type of mucosal growth and degree of dysplasia-with the exception of severe dysplasia) as well as signs of dedifferentiation (relative proportions of goblet and columnar cells) were also similar. Mucin staining intensities (periodic acid-Schiff, high iron diamine and alcian blue) and the immunoreactivity patterns of secretory component and carcinoembryonic antigen, both cytoplasmic and on the surface of the epithelial cells, were also identical in both groups of adenomas. Thus, neither the routine histological nor the mucin- and immunohistochemical features differed between the groups, except for severe dysplasia. It is concluded that there is no inherent difference in malignant potential between solitary and synchronous adenomas, with the possible exception of the degree of dysplasia.

Adenoma↗
PubMed1981

Quantitative study of the uptake of IgA by isolated rat hepatocytes.

Recently dispersed rat hepatocytes showed high capacity for uptake of monomeric and polymeric human IgA by simple absorptive endocytosis. Maximum uptake exceeded 15 million monomer units per cell. The asialo-glycoprotein receptor was not involved in this process. J chain-containing polymers were on the average taken up somewhat better than monomers and substantially better than J chain-deficient polymers. This result would agree with a partial involvement of the secretory component (SC) in the absorptive uptake of IgA. Different receptor mechanism might hence explain the hepatic transport of IgA from blood to bile in the rat and perhaps be involved in the catabolism of IgA. After binding to the plasma membrane of the rat hepatocyte, most of the human IgA was internalized in endocytic vesicles. A considerable proportion of radiolabelled IgA apparently reached the lysosomes after internalization and became degraded.

Absorption↗