Genetic variants and altered expression of SERPINF1 confer disease susceptibility in patients with otosclerosis

Otosclerosis (OTSC) is a focal and diffuse bone disorder of the human middle ear characterized by abnormal bone growth and deposition at the stapes' footplate. This hinders the transmission of acoustic waves to the inner ear leading to subsequent conductive hearing loss. The plausible convections for the disease are genetic and environmental factors with yet an unraveled root cause. Recently, exome sequencing of European individuals with OTSC revealed rare pathogenic variants in the Serpin Peptidase Inhibitor, Clade F (SERPINF1) gene. Here, we sought to investigate the causal variants of SERPINF1 in the Indian population. The gene and protein expression was also evaluated in otosclerotic stapes to ameliorate our understanding of the potential effect of this gene in OTSC. A total of 230 OTSC patients and 230 healthy controls were genotyped by single-strand conformational polymorphism and Sanger sequencing methods. By comparing the case controls, we identified five rare variants (c.72 C > T, c.151 G > A, c.242 C > G, c.823 A > T, and c.826 T > A) only in patients. Four variants c.390 T > C (p = 0.048), c.440-39 C > T (p = 0.007), c.643 + 9 G > A (p = 0.035), and c.643 + 82 T > C (p = 0.005) were found to be significantly associated with the disease. Down-regulation of SERPINF1 transcript level in otosclerotic stapes was quantified by qRT-PCR, ddPCR and further validated by in situ hybridization. Similarly, reduced protein expression was observed by immunohistochemistry and immunofluorescence in otosclerotic stapes that corroborate with immunoblotting of patients' plasma samples. Our findings identified that SERPINF1 variants are associated with the disease. Furthermore, reduced expression of SERPINF1 in otosclerotic stapes might contribute to OTSC pathophysiology.

The risks of RELN polymorphisms and its expression in the development of otosclerosis

Otosclerosis (OTSC) is the primary form of conductive hearing loss characterized by abnormal bone remodelling within the otic capsule of the human middle ear. A genetic association of the RELN SNP rs3914132 with OTSC has been identified in European population. Previously, we showed a trend towards association of this polymorphism with OTSC and identified a rare variant rs74503667 in a familial case. Here, we genotyped these variants in an Indian cohort composed of 254 OTSC cases and 262 controls. We detected a significant association of rs3914132 with OTSC (OR = 0.569, 95%CI = 0.386–0.838, p = 0.0041). To confirm this finding, we completed a meta-analysis which revealed a significant association of the rs3914132 polymorphism with OTSC (Z = 6.707, p<0.0001) across different ethnic populations. Linkage analysis found the evidence of linkage at RELN locus (LOD score 2.1059) in the OTSC family which has shown the transmission of rare variant rs74503667 in the affected individuals. To understand the role of RELN and its receptors in the development of OTSC, we went further to perform a functional analysis of RELN/reelin. Here we detected a reduced RELN (p = 0.0068) and VLDLR (p = 0.0348) mRNA levels in the otosclerotic stapes tissues. Furthermore, a reduced reelin protein expression by immunohistochemistry was confirmed in the otosclerotic tissues. Electrophoretic mobility shift assays for rs3914132 and rs74503667 variants revealed an altered binding of transcription factors in the mutated sequences which indicates the regulatory role of these variations in the RELN gene regulation. Subsequently, we showed by scanning electron microscopy a change in stapes bone morphology of otosclerotic patients. In conclusion, this study evidenced that the rare variation rs74503667 and the common polymorphism rs3914132 in the RELN gene and its reduced expressions that were associated with OTSC.

Association of ISL1 polymorphisms and eosinophilic levels among otitis media patients

Background

Otitis media (OM) is a middle ear inflammatory complex disorder involving genetic and environmental factors. It onsets during childhood and often recurs and perplexes in genetically susceptible patients. Previously, murine models had shown the association of ISL LIM homeobox 1 (ISL1) gene with otitis media with effusion.

Aim

To investigate the association of ISL1 genetic variants with otitis media.

Subjects and methods

A total of 285 cases and 277 controls were recruited for the study. The entire coding region of ISL1 gene was genotyped using Sanger sequencing or single‐strand conformation polymorphism methods. Genotype, haplotype, in silico analysis, and linkage disequilibrium analysis were performed.

Results

The variants rs2303751 (c.504A>G) and rs121913540 (c.513G>A) were associated with OM, and the OR (95%CI) was 0.74 (0.57–0.95) and 0.43 (0.20–0.91), respectively. Besides, the rs2303751 AA genotype was associated with elevated eosinophil numbers in OM when compared to controls. The 5 SNP haplotype analysis of SNPs c.‐492A>G, c.504A>G, c.513G>A, c.576C>T, and c.*651A>T revealed A‐A‐G‐C‐A to be a risk haplotype in females whereas the 3 SNP haplotype analysis of SNPs c.504A>G, c.513G>A, and c.567C>T suggested G‐A‐C as protective and A‐G‐C to be a risk haplotype for otitis media.

Conclusion

Ours is the first report which shows a significant association of ISL1 variants (rs2303751 and rs121913540) with hearing‐related disorder like otitis media in humans. These results implicate the possible role of ISL1 gene in the etiopathology of otitis media. The replication of the study in other ethnic populations may strengthen our findings.

Evaluation of the Genetic Association and mRNA Expression of the COL1A1, BMP2, and BMP4 Genes in the Development of Otosclerosis

Background: Otosclerosis (OTSC) is a genetically heterogeneous disorder, characterized by abnormal bone growth in the middle ear, affecting the stapes bone. Previous studies have shown that single nucleotide polymorphisms (SNPs) of the COL1A1, BMP2, and BMP4 genes are linked to susceptibility of OTSC, musculoskeletal degenerative diseases, and bone remodeling. Aims: To evaluate the genetic association and expression levels of COL1A1, BMP2, and BMP4 genes with OTSC in the Indian population. Methods: A total of 320 otosclerotic and 320 control samples were screened for four SNPs (rs1107946, rs11327935, rs2269336, and rs1800012) of the COL1A1 gene; rs3178250 of the BMP2 gene; and rs17563 of the BMP4 gene using single-strand conformation polymorphism analysis, and restriction fragment length polymorphism analyses. Genotypic, haplotypic, and linkage disequilibrium analyses were performed to assess the potential associations of these SNPs with OTSC. COL1A1, BMP2, and BMP4 mRNA expression levels were analyzed by semiquantitative RT-PCR and real-time PCR. Results: Genotypes of two SNPs, rs1800012 and rs17563, were found to be associated with OTSC (the rs1800012 GT genotype, p = 0.0022, OR = 0.481; and the rs17563 TC genotype, p = 0.0225, OR = 1.471). Haplotypic analyses revealed that the COL1A1 haplotype G-T-C-T (p = 0.021) was significantly increased among controls. Functional studies revealed an unexpected decrease in mRNA expression of COL1A1 but an increased expression of the BMP2 and BMP4 genes in otosclerotic stapes tissues. Conclusions: Our findings suggest that OTSC is a heterogeneous disorder, but that the GT genotype of the rs1800012 locus is protective and that the TC genotype at the rs17563 locus is a risk factor. In addition, our studies indicate that changes in the expression of the COL1A1, BMP2, and BMP4 genes may contribute to the genetic susceptibility of OTSC by regulating their mRNA levels.

Rising incidence of oral cancer in Ahmedabad city

CONTEXT

In 1999, an increase in mouth cancer incidence among young men (< 50 years) in urban Ahmedabad was reported to be occurring along with decreasing mouth cancer incidence in older age groups and increasing oral submucous fibrosis incidence associated with areca nut consumption among young men in Gujarat. The aim was to investigate whether the increase in the incidence mouth cancer that had started among young men in the 1990 s was continuing.

SETTINGS AND DESIGN

Ahmedabad urban population, comparison of reported mouth cancer cases in the population across four time period.

METHODS

Age-specific incidence rates of mouth cancer (International Classification of Diseases [ICD]-9:143-5; ICD-10:C03-06) in five year age groups among men aged ≥ 15 years for the city of Ahmedabad for years 1985, 1995, 2007 and 2010 were extracted from published reports. For comparison, lung cancer (ICD-9:169; ICD-10:C33-C34) rates were also abstracted.

STATISTICAL ANALYSIS USED

A cohort approach was used for further analysis of mouth cancer incidence. Age adjusted incidence rates of mouth and lung cancer for men aged ≥ 15 years were calculated and compared.

RESULTS

The age specific incidence rates of mouth cancer among men increased over the 25-year period while lung cancer rates showed a net decrease. Using a cohort approach for mouth cancer, a rapid increase in younger age cohorts was found.

CONCLUSIONS

Mouth cancer incidence increased markedly among men in urban Ahmedabad between 1985 and 2010, apparently due to increasing consumption of areca nut products, mawa and gutka. Gutka has now been banned all over India, but a more vigorous implementation is necessary.

Genetic association and altered gene expression of osteoprotegerin in otosclerosis patients

Otosclerosis (OTSC) is a late-onset hearing disorder characterized by increased bone turnover in the otic capsule. Disturbed osteoprotegerin expression has been found in the otosclerotic foci which may have an important role in the pathogenesis of OTSC. To identify the genetic risk factors, we sequenced the coding region and exon-intron boundaries of the OPG gene in 254 OTSC patients and 262 controls. Sequence analysis identified five known polymorphisms c.9C>G, c.30+15C>T, c.400+4C>T, c.768A>G, and c.817+8A>C. Testing of these SNPs revealed sex specific association with c.9C>G in males and c.30+15C>T in females after multiple correction. Furthermore, meta-analysis provided evidence of association of the c.9C>G polymorphism with OTSC. In secondary analysis, we investigated the mRNA expression of OPG and associated genes RANK and RANKL in otosclerotic tissues compared to controls. Expression analysis revealed significantly missing/reduced OPG expression only in otosclerotic tissues. However, the signal sequence polymorphism c.9C>G has shown no effect on OPG mRNA expression. In conclusion, our results suggest that the risk of OTSC is influenced by variations in the OPG gene along with other factors which might regulate its altered expression in otosclerotic tissues. Further research is warranted to elucidate the mechanisms underlying these observations.

Profile of dual tobacco users in India: an analysis from Global Adult Tobacco Survey, 2009-10

INTRODUCTION

Individuals who use both smoked and smokeless tobacco products (dual tobacco users) form a special group about which little is known. This group is especially relevant to India, where smokeless tobacco use is very common. The aim of this study was to characterise the profile of dual users, study their pattern of initiation to the second product, their attitudes toward quittingas well as their cessation profile.

METHODS AND MATERIALS

The GATS dataset for India was analyzed using SPSS; .

RESULTS

In India, dual tobacco users (42.3 million; 5.3% of all adults; 15.4% of all tobacco users) have a profile similar to that of smokers. Some 52.6% of dual users started both practices within 2 years. The most prevalent product combination was bidi-khaini (1.79%) followed by bidi-gutka (1.50%), cigarette-khaini (1.28%), and cigarette-gutka (1.22%). Among daily users, the correlation between the daily frequencies of the use of each product was very high for most product combinations. While 36.7% of dual users were interested in quitting, only 5.0% of dual users could do so. The prevalence of ex-dual users was 0.4%.

CONCLUSION

Dual users constitute a large, high-risk group that requires special attention.

Genetic association and gene expression profiles of TGFB1 and the contribution of TGFB1 to otosclerosis susceptibility

Otosclerosis (OTSC) is a common form of acquired hearing loss resulting from disturbed bone remodeling in the otic capsule of the middle ear. Transforming growth factor-beta1 (TGFB1) produced by osteoblasts is the most abundant growth factor in human bone. Previous studies have shown the contribution of single-nucleotide polymorphisms (SNPs) in TGFB1 toward the risk of developing OTSC in some ethnic populations. The present study was aimed at investigating the genetic association and expression profiles of TGFB1 in OTSC patients. Two SNPs (c.-800G > A and c.-509C > T) in the promoter region and three SNPs (c.29T > C, c.74G > C, and c.788C > T) in the coding region were genotyped in 170 cases and 170 controls. The genetic association analysis revealed the significant association between c.-509C > T (p = 0.0067; odds ratio [OR] = 1.562; 95% confidence interval [CI], 1.140-2.139) and OTSC. The increased minor allele "T" frequency in cases (0.42) compared to controls (0.31) indicates its possible role in the etiology of the disease. The minor allele frequencies for the SNPs c.-800G > A, c.29T > C, and c.74G >C were similar among the cases (0.04, 0.47, and 0.08, respectively) and controls (0.05, 0.42, 0.07, respectively). We found that c.788C > T was monomorphic in this population. Interestingly, a four-locus haplotype (G-T-T-G) from these SNPs was found to be significantly associated with OTSC (p = 0.0077). We identified a de novo heterozygous mutation c.-832G > A in the promoter region of TGFB1 in 1 patient. In a secondary analysis, we investigated the possibility of abnormal TGFB1 expression and irregular bone growth in OTSC by expression analysis of TGFB1 mRNA in disease tissue compared to control. We found relatively increased expression of TGFB1 mRNA in the stapes tissues of cases compared to controls (p = 0.0057). In conclusion, this study identified a risk variant c.-509C > T and a risk haplotype G-T-T-G in the TGFB1 gene that contribute toward the susceptibility to OTSC.

Epidemiology of betel quid usage

Betel quid chewing is an ancient practice common in many countries of Asia and among migrated communities in Africa, Europe and North America. It enjoys complete social acceptance in many societies and is also popular among women. In its most basic form, betel quid consists of betel leaf (Piper betel), areca nut, the main psychoactive ingredient, and slaked lime (calcium hydroxide). Areca nut is said to be the fourth most commonly used psychoactive substance in the world, after caffeine, nicotine and alcohol. There are a great variety of ingredients and ways of preparing betel quid in different countries. In some, particularly in India, tobacco is added to the quid. In recent years, commercially-manufactured non-perishable forms of betel quid (pan masala or betel quid mixtures and gutka), not containing betel leaf, have been marketed. Within a short period of about 2 decades, this industry has risen in value to several hundred US million dollars. Use of areca nut in any form is not safe for oral health; the use of commercially manufactured forms seems even riskier.

Pulmonary edema associated with scuba diving : case reports and review

Acute pulmonary edema has been associated with cold-water immersion in swimmers and divers. We report on eight divers using a self-contained underwater breathing apparatus (scuba) who developed acute pulmonary edema manifested by dyspnea, hypoxemia, and characteristic chest radiographic findings. All cases occurred in cold water. All scuba divers were treated with complete resolution, and three have returned to diving without further episodes. Mechanisms that would contribute to a raised capillary transmural pressure or to a reduced blood-gas barrier function or integrity are discussed. Pulmonary edema in scuba divers is multifactorial, and constitutional factors may play a role. Physicians should be aware of this potential, likely underreported, problem in scuba divers.

Measurement of synovial fluid and serum concentrations of the 846 epitope of chondroitin sulfate and of carboxy propeptides of type II procollagen for diagnosis of osteochondral fragmentation in horses

OBJECTIVE

To determine whether serum or synovial fluid concentrations of chondroitin sulfate epitope 846 and carboxy propeptides of type II collagen (CPII) can be used to diagnose osteochondral fragmentation (OC) in horses.

ANIMALS

38 horses with unilateral OC of the radiocarpal (n = 31) or intercarpal (33) joints and 8 clinically and radiographically normal horses. Procedures-For horses with OC, serum and synovial fluid concentrations of epitope 846, CPII, and keratan sulfate (KS) were determined, along with synovial fluid WBC counts and total protein concentrations. Serum epitope 846, CPII, and KS concentrations were measured in control horses.

RESULTS

Synovial fluid epitope 846 and total protein concentrations were significantly higher in the joints with OC than in unaffected joints, but CPII and KS concentrations and WBC counts were not. Synovial fluid total protein and 846 epitope concentrations were linearly related to grade of OC. Serum epitope 846 and CPII concentrations were significantly higher in horses with OC than in control horses. Discriminant analysis allowed 27 of 34 (79%) horses to be correctly classified as having or not having OC on the basis of serum epitope 846 and CPII concentrations.

CONCLUSIONS

Results suggest that serum and synovial fluid concentrations of epitope 846 and CPII are associated with OC. Increases in concentrations of epitope 846 and CPII suggest that increased synthesis of cartilage aggrecan and type II procollagen may be associated with OC.

CLINICAL RELEVANCE

Measurement of serum epitope 846 and CPII concentrations may be useful in the diagnosis of OC in horses.

An evaluation of dipstick-dot immunoassay in the detection of antibodies to HIV-1 and 2 in Zimbabwe

There is a need, in many developing countries, for simple and inexpensive HIV serology tests for use at the district level of health care. The Programme for Appropriate Technology in Health has developed a simple dipstick ELISA to detect antibodies to HIV-1 and 2, at a cost considerably lower than current ELISAs, which requires no specialized washing or reading equipment. In order to evaluate this dipstick under local conditions we used a panel of 546 sera selected from frozen stocks maintained by the Zimbabwe AIDS Prevention Project in Harare, Zimbabwe. Prior to storage, the sera had been tested by Abbott recombinant peptide HIV-1 and 2 ELISA and Enzygnost synthetic peptide HIV-1 and 2 ELISA. The panel included sera that were positive by both (including symptomatics and asymptomatics), negative by both, and sera showing discrepant test results. The panel was not representative of a "normal' batch of sera in Zimbabwe, and in particular included an abnormally high number of sera showing discrepant results. Thawed sera were retested using the Abbott recombinant peptide HIV-1 and 2 ELISA and concurrently with the synthetic peptide ICL-Dipstick ELISA. Both the sensitivity and specificity of the ICL Dipstick exceeded 99% when using sera that were positive or negative in all 3 plate ELISAs as the gold standard. When using sera that gave discrepant results between the two pre-storage ELISAs, most results with the ICL Dipstick concurred with findings from other test systems, including Western blot and p24 antigen detection. Considering the accuracy, low cost and case of operation of the ICL Dipstick ELISA, this test can be recommended for use for the rapid detection of antibodies to HIV at district level in developing countries.

Development of subchondral cystic lesions after articular cartilage and subchondral bone damage in young horses

The objective of this study was to determine if damage to the articular cartilage alone or articular cartilage plus subchondral bone of the distal medial femoral condyle of young, exercised horses resulted in the formation of subchondral cystic lesions. Twelve Quarter Horses (age 1-2 years), free of clinical and radiographic signs of osteochondrosis and lameness were used. In 6 horses (Group 1), a 15 times 1 mm linear full thickness defect in the articular cartilage was made arthroscopically on the weightbearing surface of the distal aspect of the medial femoral condyle. In the other 6 horses (Group 2), a 15 times 3 mm full thickness elliptical cartilage defect was made, followed by burring a 5 mm diameter, 4 mm deep hole into the subchondral bone. Three weeks after surgery, all horses were hand walked and trotted for 2 weeks and then exercised for 6 min daily, 5 days a week for the next 14 weeks on a treadmill. They were then turned onto a small paddock for 6 weeks (6 months total). The development of subchondral cystic lesions was determined using radiography. Bone activity in the femoral condyle was monitored with nuclear scintigraphy. All horses that developed subchondral cystic lesions radiographically were subjected to euthanasia for gross and histological examination of the lesions. No subchondral cystic lesions and no clinical abnormalities were detected in the horses in Group 1. Subchondral cystic lesions developed radiographically in 5 of 6 horses in (Group 2). Scintigraphic findings of horses with subchondral cystic lesions were inconsistent. Histological examination of lesions revealed variable quantities of fibrous connective tissue, fibrocartilage and bone, with evidence of bone remodelling adjacent to the subchondral cystic lesion. The results suggest that damage to articular cartilage plus subchondral bone, but not articular cartilage alone, of the distal medial femoral condyle may lead to the development of subchondral cystic lesions. These findings indicate that all subchondral cystic lesions in horses may not be osteochondrosis-type lesions and that trauma to weightbearing articular surfaces of young horses may be a predisposing factor.

Behaviour patterns which may predispose to HIV infection or further transmission and possible intervention strategy in the City of Harare. Part II

The proportion of people with AIDS is increasing rapidly in Zimbabwe. Several strategies have been adopted to check the further spread of the disease. This paper discusses the behaviour patterns which may predispose to HIV infection and possible intervention strategies that may be taken in the City of Harare. Over a third (33.9 pc, n = 1,526) of the married respondents reported that they were living separately from their spouses. There was a high proportion (76.6 pc, n = 564) of single respondents who admitted to engaging in premarital sex. Fifteen pc of total respondents were engaging in casual sex. The proportion of single respondents (31.2 pc) engaging in casual sex was higher than among the married (11.1 pc). More single respondents (10.9 pc) had been paid for sex than the married (4.1 pc) whilst the proportion that had been paid for sex was similar for the single (21.2 pc) and the married (22.9 pc). The median age for starting sex was 17 years (range = three to 26) for the single and 18 years (range = four to 35) for the married respondents. Sixteen pc stated that they had an STD in 1989. Condom usage was low with only 9.2 pc always using a condom. Forty eight pc of the married respondents who have engaged in casual sexual relationships never use condoms. The main source of information on AIDS/HIV was the radio (74 pc). Most parents (66 pc) had not talked about AIDS to their children.

Knowledge and attitudes on AIDS relevant for the establishment of community care in the city of Harare

Part I: Because of the increasing number of people with the HIV infection or AIDS, health resources and facilities are becoming over burdened. Many projects are looking towards involving communities more in caring and supporting those living with HIV/AIDS. In view of this, features of knowledge and attitudes have been drawn out of a main study on knowledge, attitudes and practices on 2 109 respondents in the City of Harare, to demonstrate areas where urgent preparation is needed to facilitate community care. The majority of respondents (96 pc) were aware that AIDS is a sexually transmitted disease. About 70 pc of the respondents thought that there were many people infected with HIV in Zimbabwe. Most of the respondents (83.3 pc) were frightened by the idea of catching AIDS. However, 82 pc would want to know if they are infected with the AIDS virus. About nine pc of the respondents said that they would commit suicide on discovering that they had HIV. Only 10 pc would have another child after becoming infected. A quarter of the respondents would not be supportive of people with AIDS. They stated that they would evict lodgers with AIDS, would avoid either neighbour, coworker or school mate with AIDS. People were generally more willing to look after their own children (76 pc) and less supportive of other relatives (68 pc) who had AIDS. Gender differences are also highlighted.

Therapeutic review: tuberculosis

Tuberculosis (TB) is increasing in Zimbabwe and other countries in Africa and world-wide. TB treatment and control face new difficulties including the impact of the HIV epidemic and drug resistance. There is now abundant evidence that six-month regimens are highly effective and, by improving compliance, can improve results and the cost-effectiveness of therapy. Intermittent therapy reduces drug costs and allows for the possibility of complete supervision. The optimal management of the HIV-infected TB patient has not yet been established but an increased rate of drug reactions suggests that standard treatment should be reassessed.

High resolution computed tomography and lung function in asbestos-exposed workers with normal chest radiographs

Asbestos-exposed persons with normal chest radiographs can demonstrate parenchymal abnormalities on high resolution computed tomography (HRCT). We reviewed the HRCT, clinical presentation, and results of pulmonary function tests in 169 asbestos-exposed workers with normal chest radiographs (ILO less than 1/0). The HRCT was normal or near normal in 76 subjects (Group 1), abnormal but indeterminate for asbestosis in 36, and abnormal and suggestive of asbestosis in 57 (Group 2). The indeterminate subjects were excluded from further analysis. The subjects in Groups 1 and 2 were not significantly different in their duration of asbestos exposure, latency, smoking history, or in measurements of airflow obstruction (FEV1/FVC% and %FEV1). Both the vital capacity percent predicted and diffusing capacity percent predicted were significantly lower in the abnormal subjects (Group 2) than in the normal subjects (Group 1) (79.0 versus 86.2, p = 0.005; 78.2 versus 87.1, p = 0.024; independent t test). We conclude that in asbestos-exposed subjects with normal chest radiographs, HRCT can identify a group of subjects with significantly reduced lung function indicative of restrictive lung disease when compared with a group with normal or near-normal HRCT.

Asbestos-related focal lung masses: manifestations on conventional and high-resolution CT scans

In 260 asbestos-exposed individuals evaluated by means of computed tomography (CT), 43 unsuspected pulmonary masses were found in 27 individuals. The masses included fissural pleural plaques (n = 10), dense fibrotic bands (n = 3), round atelectasis (n = 11), carcinomas (n = 3), and other presumed benign masses (n = 16). The most helpful features in the diagnosis of rounded atelectasis with CT were (a) contiguity to areas of diffuse pleural thickening, (b) a lentiform or wedge-shaped outline, (c) evidence of volume loss in the adjacent lung, and (d) a characteristic "comet tail" of vessels and bronchi sweeping into the margins of the mass. Less advanced areas of focal atelectasis had fewer classic features. Intrafissural pleural plaques were readily identified with high-resolution CT. In asbestos-related masses, the demonstration of stability over time is necessary. Careful interpretation of CT and high-resolution CT features and close surveillance can obviate the need for biopsy in the majority of instances.

High-resolution CT of benign asbestos-related diseases: clinical and radiographic correlation

We prospectively analyzed benign asbestos-related pleural and parenchymal abnormalities on high-resolution CT scans and correlated them with clinical diagnoses in 100 asbestos-exposed workers. All subjects had high-resolution CT scans in conjunction with conventional CT at the time of clinical evaluation. To evaluate for asbestosis, we ranked high-resolution CT scans as high, intermediate, or low probability of asbestosis on the basis of the multiplicity and extent of observed parenchymal changes. By linear regression analysis, the most distinctive high-resolution CT features of asbestosis included thickened nondependent interstitial short lines and parenchymal bands. In 45 subjects satisfying clinical criteria of asbestosis, high-resolution CT probability of asbestosis was high in 38 (84%), intermediate in five (11%), and low in two (4%). In 20 (36%) of 55 subjects without clinical asbestosis, parenchymal abnormalities indicative of a high probability of asbestosis were observed on high-resolution CT. High-resolution CT probability scores had a strong positive correlation with chest radiographic profusion scores (p less than .0001) and asbestos-related pleural thickening (p less than .0001). Significant inverse correlations were seen with forced vital capacity (p less than .006) and single-breath diffusing capacity (p less than .03), both functional measures of restrictive interstitial lung disease. Neither clubbing nor rales were sufficiently prevalent to have statistical correlation with high-resolution CT scores. High-resolution CT is sensitive in detecting both pleural and parenchymal abnormalities in the asbestos-exposed subject. Asbestos-related pleural changes are observed more frequently on high-resolution CT than on conventional CT or chest radiography. The probability of asbestosis based on high-resolution CT parenchymal features has a significant correlation with existing clinical determinants of disease, and high-resolution CT can detect abnormality when other methods are not diagnostic.

Asbestos-related pleural and parenchymal fibrosis: detection with high-resolution CT

Twenty-nine subjects with occupational asbestos exposure and clinical asbestosis were examined with high-resolution computed tomography (HRCT) to determine its sensitivity, relative to that of conventional computed tomography (CT), for detection of benign asbestos-related disease. Thin-section HRCT scans were obtained at five discrete levels through the mid and lower thorax in both prone and supine positions. The same technique was used in 34 age-similar control patients. Parenchymal abnormalities were seen most frequently in the posterior portion of the lung bases in the asbestos-exposed subjects. HRCT prone scans enabled basal structural abnormalities to be reliably distinguished from gravity-related physiologic phenomena in 25 asbestos-exposed subjects. HRCT was more sensitive than CT in detection of both pleural and parenchymal fibrosis. In subjects with clinical asbestosis, HRCT demonstrated parenchymal abnormality in 96%, compared with 83% for CT. Similarly, pleural thickening was shown in 100% of subjects at HRCT, compared with 93% at CT. HRCT could be an important adjunct in the evaluation of asbestos-related pleuroparenchymal fibrosis. An HRCT study including prone scans is a sensitive, reliable means of detecting thoracic abnormalities in asbestos-exposed individuals.

Pulmonary function abnormalities in patients with CT-determined emphysema

The CT quantification of both the extent and severity of emphysema was undertaken in 30 subjects. The CT scans at five preselected anatomic levels were analyzed using two methods. Correlation of the results of the CT methods were with pulmonary function results of airway obstruction and alveolar diffusion for carbon monoxide. Analysis by direct observation of the CT scans gave insignificantly different results for a complex grid method of analysis. The emphysema score with the observational method had a positive correlation with airflow obstruction (r = -0.817) as did the score with the grid method (r = -0.873). The diffusing capacity for carbon monoxide also correlated with both emphysema scores. The CT methods for quantifying emphysema correlate closely with functional abnormalities. As previously demonstrated with pathological assessment of lung slices for emphysema, direct observation of CT scans is as precise as a more complex grid method.

Effects of obesity on respiratory function

Obesity, because it alters the relationship between the lungs, chest wall, and diaphragm, has been expected to alter respiratory function. We studied 43 massively obese but otherwise normal, nonsmoking, young adults with spirometry, lung volume measurement by nitrogen washout, and single-breath diffusing capacity for carbon monoxide (DLCO). Changes in respiratory function were of two types, those that changed in proportion to degree of obesity--expiratory reserve volume (ERV) and DLCO--and those that changed only with extreme obesity--vital capacity, total lung capacity, and maximal voluntary ventilation. When compared with commonly used predicting equations, we found that mean values of subjects grouped by degree of obesity were very close to predicted values, except in those with extreme obesity in whom weight (kg)/height (cm) exceeded 1.0. In 29 subjects who lost a mean of 56 kg, significant increases in vital capacity, ERV, and maximal voluntary ventilation were found, along with a significant decrease in DLCO. Because most subjects fell within the generally accepted 95% confidence limits for the predicted values, we concluded that obesity does not usually preclude use of usual predictors. An abnormal pulmonary function test value should be considered as caused by intrinsic lung disease and not by obesity, except in those with extreme obesity.