Occult hepatitis B infection in blood donors at Zagazig university hospitals, Sharkia governorate

Although, the incidence of transfusion-transmitted hepatitis B virus [HBV] has been reduced over last four decades, HBV remains the most frequent transfusion-transmitted infection .The aim of this study is to determine the percentage of anti-HBc positivity in HBsAg negative blood donors' samples and to estimate the frequency of HBV-DNA in HBsAg negative/anti-HBc positive and in some HBsAg/anti-HBc negative samples and to assess the presence of this OHBI in HBsAg negative HCV positive samples. Randomly selected 500 blood donors referred to Blood Bank, Zagazig University Hospitals at Sharkia Governorate were included, after routine blood bank serological tests, ALT and AST, total anti-HBc were done for blood samples that were negative for HBsAg. Samples were divided into two main categories according to their HCV Ab status [450 were negative for HBsAg, HCV Ab, HIV Ag/Ab and RPR and 50 were negative for HBsAg, HIV Ag/Ab and RPR but HCV positive], anti-HBs quantification, HBV-DNA by real-time PCR was performed for all samples anti-HBc positive and some randomly selected anti-HBc negative samples. The percentage of total anti-HBc among HBsAg negative blood donors, [HCV Ab negative] was 20.8% [94/450] and in [HCV Ab positive] was 26% [13/50]. The frequency of HBV-DNA in [HBsAg/HCV Ab negative] was 6/94 [6.4%] of anti-HBc positive blood donors and not detected in the randomly selected anti-HBc negative donors [0/16]. The percentage of HBV-DNA was higher in HCV Ab positive [13.3%] than HCV Ab negative donors [5.5%]. Most Occult Hepatitis B Infection [OHBIs] are asymptomatic, only be detected by systematic screening of large populations, detection of OHBI requires addition of anti-HBc tests along with HBsAg ending with NAT to donated blood screening tests for improving blood safety

Monthly abundance of rodent and their ectoparasites in newly settled areas, east of lakes, Ismailia governorate, Egypt

Rodents and their ectoparasites were studied inside and outside houses in the newly settled areas, east of lakes, Ismailia Governorate, Egypt. Forty traps per month in each of the two sides were used for collecting rodent during 2009. From 221 rodent were collected from inside houses; Mus musculus N=115 [52.04%], Rattus rattus. frugivorous N=54 [24.43%], R. r. alexandrinus N=40 [18.10%] and R. norvegicus N=12 [5.43%]. From 177 rodent were collected from outside houses; M musculus N=4 [2.3%], R. r. frugivorous N=29 [16.43%], R r. alexandrinus N=37 [20.9%], R. norvegicus N=36 [20.3%], Gerbillus pyramiduin N=67 [37.9%] and Jaculus jaculus N=4 [2.3%]. Total ectoparasites per rat inside houses were 765 [3.46 E/Rat] which were classified as fleas, N=464 [2.11 F/R]; lice N=150 [0.68 L/R] and mites N=151 [O.68 M/R]. From outside house, total ectoparasites per rat were 984 [5.5 E/R] which were classified as fleas, N=410[2.31 F/R]; lice N=100 [0.56 L/R], mites N=400 [2.23 M/R] and ticks, N=74 [0.42 T/R]. From indoors two fleas species were recorded [Xenopsylla cheopis and Ctenopsyllus segnis]; one species of lice [Polyplax spinulosa] and four species of mites [Laelaps nuttall, Ornithonyssus bacoti, Dermanyssus gallinae and Eulaelaps stabularis]. The outdoors ectoparasites were; six fleas species [X cheopis, X ramesis, Pulex irritans, C. segnis, Stenoponia tripectinata and Nosopsylla sinaiensis]; one lice species [P. spinulosa]; Six mites species [L. nuttalli O. bacoti, D. gallinae, E. stabularis, Haemogamasus pontiger and Hirstionyssus isabellinus] and immature stages of two ticks species [Rhipicephalus sp. and Hyalomma sp.]. Most of these ectoparasites were recorded infesting G. pyramidum

Morpho-physiological and biochemical criteria of acanthamoeba spp. isolated from the Egyptian aquatic environment

The free-living amoebae Acanthamoeba spp., have been recognized as etiologic agents of amoebic encephalitis, keratitis, otitis, lung lesions and other skin infections mainly in immunocompromised individuals. In this study, morpho-physiological and biochemical characterization of Acanthamoeba strains isolated from the Egyptian aquatic environment were surveyed. Some Acanthamoeba species were cultivated on non-nutrient agar. Isolated strains of Acanthamoeba were identification based on the morphology of trophic and cyst forms in addition to temperature and osmo-tolerance assays. Biochemical characterization of the isolated amoeba strains was performed using quantitative assay as well as qualitative determination of proteolytic activity in zymograph analysis. Potentially pathogenic Acanthamoeba species were isolated from all of the examined water sources. Colorimetric assays showed protease activity in the heat-tolerant isolates of Acanthamoeba. All pathogenic isolates of Acanthamoeba exhibited higher protease activity than did the non-pathogenic ones. The zymographic protease assays showed various banding patterns for different strains of Acanthamoeba. The incidence and prevalence of the pathogenic Acanthamoeba species in the aquatic environment using parasitological and biochemical diagnostic tools will provide baseline data against which the risk factors associated with waterborne transmission can be identified.

Digestive enzyme as benchmark for insecticide resistance development in culex pipiens larvae to chemical and bacteriologic insecticides

This work monitored changes in some digestive enzymes [trypsin and aminopeptidase] associated with the building up of resistance in Cx. pipiens larvae to two chemical insecticides [methomyl and/or malathion] and one biological insecticide [Bacillus thuringiensis-H14 or B.t HI4]. The LC[50] value of methomyl for both field and the 12[th] generation [F12] of the selected strain was 1.789 ppm and 8.925 ppm respectively. The LC[50] value of malathion for both field and the F12 of the selected strain was 0.082 ppm and 0.156 ppm respectively, and those of B.t H14 of field strain and the F12 was 2.550ppm and 2.395ppm respectively. The specific activity of trypsin enzyme in control susceptible colony was 20.806 +/- 0.452[micromol/min/mg protein; but at F4 and F8 for malathion and methomyl treated larvae were 10.810 +/- 0.860 and 15.616 +/- 0.408 [micromol/min/mg protein, respectively. Trypsin activity of F12 in treated larvae with B.t.H14 was 2.097 +/- 0.587micromol/min/mg protein. Aminopeptidase specific activity for susceptible control larvae was 173.05 +/- 1.3111micromol/min/mg protein. This activity decreased to 145.15 +/- 4.12, 152.497 +/- 6.775 and 102.04 +/- 3.58 [a]micromol/min/mg protein after larval [F12] treatment with methomyl, malathion and B.t H14 respectively

Study of the pituitary-gonadal axis in the proestrus phase in adult female rats subjected to social isolation

Social isolation is a type of stress that might adversely affect sex cycles in both animals and humans. The present study was planned to investigate the pituitary-gonadal axis in the proestrus phase of estrous cycle in adult female rats subjected to social isolation stress for 8 weeks. Twenty Sprague-Dawley adult female rats were divided into two experimental groups: a control group [n = 10] and a socially isolated group [SI, n = 10]. Throughout the study, all rats were monitored for body weight and food intake. After 8 weeks, rats were sacrificed in the proestrus phase of estrous cycle. All rats were examined for final body weight, rectal temperature, hematocrit value, and serum levels of follicle stimulating hormone, luteinizing hormones, prolactin hormone, 17-beta estradiol, and progesterone in addition to histological examination of the ovaries. The results of the present study showed that the SI group had significant decrease in their final body weights and their serum levels of 17-beta estradiol and progesterone, whereas the serum level of prolactin was significantly increased. Histological examination of SI rat ovaries showed fewer growing ovarian follicles and numerous atretic ones compared to control rat ovaries. These findings indicate that social isolation might result in depressed ovarian function in adult female rats

Cross-reaction of antigen preparations from adult and larval stages of the parasite Setaria equina with sera from infected humans with Wuchereria bancrofti

Crude antigenic preparations from Setaria equina were used in ELISA and Western blotting to examine cross-reaction with human sera from areas endemic for bancroftian filariasis. Sera from normal subjects from non-endemic areas were included as negative controls. Cross-reaction was found between 5. equina antigens and antibodies in the sera of Wuchereria bancrofti-infected patients, with the highest levels observed between sera of chronic infected patients and Setaria spp. crude female worm surface antigen [CFSWA]. In the absence of active transmission of Setaria spp. infection, CFWSA is useful to detect chronic W. bancrofti infection before patients become symptomatic, particularly when chronic patients are known to be amicrofilaraemic. In the presence of active 5. equina infection, antigens from the adult and microfilaraemic stages showed the highest degree of cross-reaction with human sera

Metabolic effects of streptozotocin-induced diabetes in ovarectomized rats

Little information is available about how the changes that occur around the time of menopause might affect management of diabetes mellitus .The present study investigates the metabolic consequences of estrogen deficiency with streptozotocin induced-diabetes. The study was performed on 130 female Wistar rats, allocated into 4 groups: control [Sham]; diabetic [STZ]; ovarectomized [OVX] and ovarectomized diabetic [OVX-STZ] .Rats were subjected to determination of body weight and body mass index [BMI]. Estimation of blood glucose, plasma levels of insulin, estradiol, leptin, malondialdehyde, lipids, atherogenic index as well as in vitro diaphragmatic glucose uptake and renal glucose output. OVX- STZ rats showed significantly lower body weight and BMI than OVX rats. Blood glucose level was significantly higher than Sham, STZ and OVX groups. Diaphragmatic glucose uptake significantly decreased, while renal glucose output significantly increased compared to OVX and Sham groups .Plasma lipid profile in OVX-STZ rats was worse than Sham, STZ and OVX groups as indicated by the significant increase in plasma triglycerides, total plasma cholesterol and LDL-c. Atherogenic index was significantly higher than Sham and OVX rats. Similarly, lipid peroxidation was significantly higher than Sham, STZ and OVX groups. Plasma insulin decreased significantly compared to Sham, STZ and OVX groups, while the decrease in plasma leptin was significant when compared to Sham group. The present study demonstrates that metabolic derangements of combined insulin and estrogen deficiency overweigh the derangement of either hormone deficiency in postmenopausal period

Zoonotic helminthes of commensal rodents in Talkha center, Dakahlia governorate

Commensal rodents were trapped alive from different areas near garbage, canal edges, farm animals and the likes in Talkha Center over one year. A total of 135 rodents were collected, their species and index were Rattus norvegicus [0.11], R. r. frugivorous [0.13], R. r. al-exandrinus [0.16] and Mus musculus [0.5]. The zoonotic helminthes were trematodes [10 species], cestodes [4 species], and nematodes [10 species]. The results were discussed on light of other works

Formation constants, spectral and thermal properties of lanthanide complexes with D-penicillamine Disulfide

The complex-formation of the lanthanide[III] elements with D-penicillamine disulfide has been investigated in acidic and neutral media. The macroscopic protonation constants of the ligand and the formation constants of [Ln.Pds][+], [LN.[Pds][2][-], [Ln.Pds.OH] and [LN.Pds.[OH][2]][-] complexes were determined from pH-metric data using BEST computer program. Species distribution diagrams of the formed complexes are obtained and plotted using SPE and SPEPLOT computer programs. Elemental analyses of the solid complexes indicate the formation of 1:1 metal:ligand species. The binding sites in the complexes with a special regard to the possible role of-COO[-] and-NH[2] groups in the coordination have been discussed using infrared data. The complexes decompose in four steps as shown by their t.g.a. and d.t.a. analysis with the formation of Ln[2]O[2]SO[4] as a final product. Activation energy delta E[a] was calculated and correlated with type of complexed metal. Mechanism of thermal decomposition is proposed

Ectoparasites of commensal rodents in Talkha center, Dakahlia governorate, Egypt

The ecto-parasites infesting commensally rodents were collected from the different localities in Talkha Center [Dakahlia Governorate] from April 2006 to March 2007. The seasonal abundance of rodent number and rat index was 52 [0.58] in spring, 27 [0.3] in summer, 39 [0.22] in autumn and 17 [0.05] in winter. From 135 rodent species and rat index was Rattus norvegicus N=33 [0.24], R. r. frugivorous N=39 [0.29], R. r. alexandrinus N=48 [0.36] and Mus musculus N=15 [0.11]. From 388 ecto-parasite infested rodent collected number and ecto index was fleas N= 114 [0.84 flea/rat], Lice N=93 [0.69 lice/rat], Mites N= 165 [1.2 mite/rat] and larva of ticks N=16 [0.12 tick/rat]. No doubt, rodents and their ectoparasites played a serious role in spreading and transmission of zoonotic diseases to human and animal

Sensory, physico-chemical and microbial characteristics of new light mayonnaise formulations

The effect of oil type [sunflower, corn, soybean, olive and palm] at different oil concentrations [10 to 35%], stabilizer type [RR MAYLI 6, xanthan gum, guar gum and locust bean gum; each alone or in combination] and stabilizer concentration [0.5-5.0%] on the sensory attributes [color, texture, taste and overall acceptability], physico-chemical properties [emulsion stability, apparent viscosity, moisture content, total solids, acidity, pH, peroxide value and hydrolytic stability] and microbial quality of several light mayonnaise [LM] formulations during storage at refrigerator temperature [4°C +/- 2] and at room temperature [24°C +/- 2] were examined. LM prepared with sunflower oil [25%] exhibited the highest sensory scores and stability even when compared with the traditional high fat mayonnaise [75% oil]. On the other hand, olive and palm oil exhibited very low sensory scores. LM formula containing 25% sunflower oil and 5% RR MAYLI 6 showed great chemical, physical and microbial stability during the 12 months of storage at room temperature. Also, this formula was rated by the panelists as the formula of choice when compared with other LM tested formulations, traditional high fat mayonnaise [75% oil] and other imported LM brands available in the Egyptian markets. Cold storage did not significantly affect the sensory quality. However, it significantly reduced the deterioration in the physico-chemical properties of the LM formulations. LM formulations very low in oil [15 and 10% oil] were successfully achieved using xanthan gum [1.5%] and a mixture of xanthan and guar [0.75:0.75%] respectively. In spite of their very low oil contents, they exhibited sensory shelf life of 4 months. Such formulations are considered to be the lowest in oil content amongst those reported in the literature

Spectral and landscape characterization of filarious and non-filarious villages in Egypt

Filarial disease is endemic in Egypt in some villages of Nile Delta governorates where it is transmitted by Culex pipiens female. GIS functions are used to identify environmental indicators of high-risk village as indicated by mosquito density, human infection rate, vector species composition, mean life expectancy "e0" and environmental variables [geology, hydrology, soil types, etc] as well as meteorological factors [temperature, RH and rainfall] in relation to filaria transmission risk. Remote-sensing technology was used to distinguish between the two studied villages as high and non-infected, as defined by microfilarial prevalence. The results indicate that filaria transmission risk is higher at an area characterized by highly productive aquifers, silt clay soil, receiving little amount of rain with low relative humidity [RH]. The results indicate that the most important landscape elements associated with preva1ence are Water and different vegetation. This work showed that the integration between GIS and remote sensing technologies to analyze and identify the environmental factors, associated with the disease, did not only allow mapping current spatial patterns, but also predicting its distribution under expected future developmental and environmental changes

Biochemical fingerprints of salviary gland for some ticks species in Egypt by SDS-polyacrylamide gel electrophoresis

SDS-PAGE gel electrophoresis as a sensitive method is used for simultaneously comparing the total protein extracted from salivary glands in some ticks species [Argas persicus, Hyalomma antolicum excavatum, H. an antolicum, H. dromedarii, H. impeltatum and Rhipicephalus sanguineus]. The results of A. persicus were characterized by 4 bands with molecular weights ranging from 82.76 to 16.076 KD. On the other hand, H. an. excavatum females were characterized by 6 bands with molecular weights ranging from 103.74 to 6.216 KD. H. an. antolicum males were characterized by 5 bands with molecular weights ranging from 79.183 to 2.092 KD. R. sanguineus was characterized by 4 and 8 bands with molecular weights ranging from 88.864 to 6.216 KD and 126.69 to 7.1 12 KD for male and female, respectively. Female H. impeltatum was characterized by 8 bands with a range of molecular weights from 106.96 to 7.829 KD. H. dromedarii was characterized by 4 and 7 bands with ranges of molecular weights from 88.147 to 4.602 KD and 110.20 to 2.630 KD for male and female, respectively

Role of estimation of serum CA125 in the diagnosis and prognosis of spontaneous bacterial peritonitis

Cancer antigen [CA] 125 is the only known glycoprotein marker increased by active synthesis by peritoneal epithelium in the presence of ascites alone. The aim of this work is the evaluation of diagnostic and prognostic significance of serum CA125 in cases with spontaneous bacterial peritonitis [SBP]. Two groups of patients were examined for serum level of CA125. Group I: 20 patients with cirrhotic ascites and SBP, diagnosed by ascitic PMN count >/= 250/mm[3] and positive ascitic fluid culture. Group ll: 24 patients with sterile cirrhotic ascites. Other causes of CA 125 elevation [mainly malignancies and gynecological diseases] were excluded. All cases with SBP were treated and the serum CA 125 level was re-tested in the 10 patients who completed therapy. Significantly elevated levels of serum CA125 were found in patients with SBP [group I] which were more than that found in group II [338.8 +/- 89.9 vs. 149.3 +/- 58.6, p<0.001]. This increase of CA125 in SBP cases was not related to amount of ascites, type of causative bacteria, cause of cirrhosis, liver and kidney function tests, or ascitic PMN count. Therapy of SBP led to significant decrease of CA 125 in survivors [1 55 +/- 37.85vs. 309.5 +/- 42.4, p< 0.001]. The sensitivity, specificity and diagnostic accuracy of serum CA 125 in diagnosis of SBP [when the cut- off level was 240/Uml] were 100%, 83.3% and 90.9% respectively, although it had no prognostic value. In conclusion serum CA 125 can be used as easy and rapid screening test to diagnose of SBP

Outdoor resting and nectar feeding behaviour of some mosquito species in two villages in Egypt

Mosquito samples resting on different host plants were collected from 2 localities in Egypt, Kafr Tohoria Village, Qalyoubia Governorate, and El-Abttal Village, Ismailia Governorate. Collected mosquitos were identified, classified according to their feeding stage and tested for carbohydrate feeding. Results indicated that Cx. pipiens represented 96% and above of collected species in the 2 localities. The available plants and crops showed different attraction levels for resting female mosquitos. Most of the collected females were empty. Mosquitos may be attracted to certain plants due to the presence of some phagostimulant chemicals rather than the presence of the sugars

Haemoglobinometry as a method to determine the blood meal size of two argasid tick specties

A standardized clinical method for measuring hemoglobin was applied to measure the quantity of blood ingested by Argas persicus and A. hermanni feeding on chicken and pigeons, respectively. The blood fed ticks were added to a reagent that converted all hemoglobin to hemoglobincyanide [HiCN], which can be read spectrophotometrically. The validity of this method was established by comparing hemoglobin determination with the size of blood meals measured by weight. Linear relationships with high correlation coefficients were obtained for nymphs, males and females of A. persicus and A. hermanni, showing that both gravimetric [weighing] and HiCN methods gave similar estimates of ingested blood

Evaluation of the role of ancylostoma caninum in human as a cause of acute and recurrent abdominal pain

Ninety-five patients with obscure acute or recurrent abdominal pain and ten asymptomatic healthy parasite free cases were subjected to thorough history taking, clinical examination, sonography, routine laboratory investigations and sero-testing by IgG ELISA to detect antibodies to excretory/secretory [ES] antigens of adult A. caninum and by IgG and IgG4 Western blot [WB] to detect antibodies to Ac68 antigen. Eleven male patients [5 with acute abdomen, 3 diagnosed as appendicitis and 3 had recurrent mild to moderate abdominal pain] fulfilled the criteria of case definition of human enteric infection with A. Caninum [GI]. The study also detected human hookworm infection in 14 patients [G.IIb], other parasites in 34 patients [GIIc] and 36 patients had no parasite [G.IIa]. Although 3 patients from group I were diagnosed as appendicitis and were dealt with surgically, the pain recurred and mebendazole only ameliorated the patients complaints. The obtained appendices of these operated cases showed marked eosinophilic infiltration, but no adult canine hookworms were detected. IgG ELISA was positive in 72.7%, 8.3%, 100%, 23.5% and 0% in groups and control, respectively

Oxidative stress in diabetes mellitus

Plasma levels of lipid peroxide [malondialdehyde] [MDA] and erythrocyte superoxide dismutase [SOD] activity were measured in 15 diabetic patients without complications, 30 diabetic patients with microvascular complications [retinopathy and /or nephropathy] and in 10 healthy control subjects. Results showed a highly significant increase in plasma levels of MDA among the diabetic patients in comparison to the control subjects and in diabetic patients with complications in comparison to those without complications. Also, there was a highly significant decrease in erythrocyte SOD activity in the diabetic patients in comparison to the control subjects and in diabetic patients with complications in comparison to those without complications. A highly significant positive correlation was found between plasma levels of MDA and each of fasting blood glucose, duration of diabetes mellitus and microalbuminuria

Estrogen replacement therapy, and serum lipid values

To examine the effect of estrogen replacement therapy [ERT] on lipid values in postmenopausal women, lipid profiles were obtained in 50 postmenopausal women. Women were divided into two groups, group [1] [20 women] were not receiving any hormonal treatment and group [2] [30 women] were receiving unopposed ERT. Fifteen women [subgroup A] of the ERT users were receiving oral estrogen [0.625 mg daily] and fifteen women [sub group "B"] were receiving transdermal patches with estrogen [delivering 0.1 mg daily]. The two groups were matched for the same age group, years after menopause, socioeconomic class and body mass index. The Mean high-density liporotein [HDL] cholesterol level was significantly higher [70 +/- 5 vs 60 +/- 7 P< 0.05] and mean total / HDL cholesterol ratio significantly lower in women receiving estrogen than in those who were not [3.7 +/- 0.3 vs 4.9 +/- 0.6]. Total cholesterol level [263 +/- 35 vs 295 +/- 33] and LDL cholesterol level [169 +/- vs 200 +/- 25] were significantly lower in women receiving ERT than those who were not. These results are in agreement with those of Paganini et al [1996] and Hong et al [1992]. Triglycerides levels showed no significant differences between group [1] and group [2]. Women of subgroup [A] had a significant higher level of triglycerides than women in subgroup [B] [221 +/- 35 vs 189 +/- 25] and than women in group [1] [221 +/- 35 vs 194 +/- 23]. Denek [1995] and Hong et al [1992] reported the same results in their studies. With exception of triglycerides no significant difference in lipid values was found between the two subgroups. The study showed that women taking ERT have a more favorable lipid profile than those who were not. The triglyceride levels was augmented by oral ERT and not affected by transdermal estrogen

Ultrastructure of the tracheobronchial epithelium of the normal and formaldehyde-exposed guinea-pig

Thirty adult male guineca pigs were used in this study, fifteen taken as control, while the other fifteen were exposed to formaldehyde.The tracheobronchial epithelium of all animals were examined by means of light and electron microscopy. The tracheobronchial epithelium of the control animals was found to consist of ciliated, goblet, basal and intermediate cells. The general structure of the epithelium is suggested to provide a barrier restricting the transfer of exogenous material from the airway lumen to the blood stream. Moreover, the actively motile cilia of the ciliated cells are responsible for transport of mucus with included foreign materials to the throat where the mucus normally swallowed. The goblet cells continuously secrete mucus which formed a physical barrier between the inhaled pollutants and underlying epithelium. The results of this work suggest that, both motile cilia and secretion of correct amount of mucus with suitable vesicoelasticity are responsible for maintenance of mucociliaryy clearance. Also the intermediate cells were observed to be differentiated into goblet cells. Following formaldehyde exposure, profound general and special epithelial and submucosal changes, ranging from moderate to severe were observed within the tracheobronchial epithelium.Early after short periods of formaldehyde exposure, the structural changes in the bronchial epithelium were observed to be less severe than that of the tracheal epithelium. However, later on, with prolongation of the period of formaldehyde exposure, both trachea and bronchi were severely affected. The general epithelial changes included, 1] ulceration of the tracheobronchial epithelium which is emphasized to expose and sensitize the airway receptors to inhaled irritants which are responsible for the pathogenesis of occupational asthma. 2] proliferative changes in the form of simple hyperplasia, basal and goblet cell hyperplasia and squamous metaplasia have occurred and suggested the possibility of formaldehyde carcinogenicity 3] thickening of the basement membrane which is considered to be a protective mechanism against inhaled formaldehyde. On the other hand, the special epithelial changes were evidenced by the appearance of a great number of ciliary abnormalities and apocrine, massive mucus secretion of the goblet cells with subsequent impairment of the mucociliary clearance. Both fibrosis and airway obstruction are considered to be the latest sequlae of long term injury produced by formaldehyde exposure as indicated by the appearance of fibroblasts and smooth muscle fibers within the submucosa of tracheobronchial epithelium