Circulating miRNAs in the first trimester and pregnancy complications: a systematic review

Most pregnancy complications originate with early placentation. MicroRNAs (miRNAs) may play an important role in placentation and function as biomarkers of future pregnancy complications. We summarized from the literature all first trimester circulating miRNAs associated with pregnancy complications of placental origin and further identified the miRNAs which have the most evidence as potential early biomarkers for pregnancy complications. We conducted a systematic review following PRISMA reporting guidelines (PROSPERO CRD42020183421). We identified all first trimester serum or plasma miRNAs associated with a pregnancy complication of placental origin (preeclampsia, intrauterine growth restriction (IUGR), gestational hypertension, preterm delivery) and the number of times those miRNAs were identified, as a measure of replication. Twenty-one studies examined 118 unique miRNAs, and 87 were associated with at least one pregnancy complication; preeclampsia was the most common. Seven miRNAs were significantly associated with a pregnancy complication in at least two studies: miR-125b, miR-518b, miR-628-3p, miR-365a-3p, miR-520h, miR-374a-5p, miR-191-5p. Few miRNAs were associated with more than one pregnancy complication: miR-518b and miR-520h with preeclampsia and gestational hypertension, miR-374a-5p and miR-191-5p with preterm birth and preeclampsia. Our systematic review suggests seven miRNAs as potential biomarkers of pregnancy complications. These complications are thought to originate with early placental defects and these miRNAs may also be biomarkers of placental pathology. First-trimester biomarkers of pregnancy complications can facilitate early detection and interventions.

Adding MR Diffusion Imaging and T2 Signal Intensity to Neck Imaging Reporting and Data System Categories 2 and 3 in Primary Sites of Postsurgical Oral Cavity Carcinoma Provides Incremental Diagnostic Value

BACKGROUND AND PURPOSE

The NI-RADS lexicon doesn't use ADC parameters and T2 weighted signal for ascribing categories. We explored ADC, DWI, and T2WI to examine the diagnostic accuracy in primary sites of postsurgical oral cavity carcinoma in the Neck Imaging Reporting and Data System (NI-RADS) categories 2 and 3.

MATERIALS AND METHODS

We performed a retrospective analysis in clinically asymptomatic post-surgically treated patients with oral cavity squamous cell carcinoma who underwent contrast-enhanced MRI between January 2013 and January 2016. Histopathology and follow-up imaging were used to ascertain the presence or absence of malignancy in subjects with "new enhancing lesions," which were interpreted according to the NI-RADS lexicon by experienced readers, including NI-RADS 2 and 3 lesions in the primary site. NI-RADS that included T2WI and DWI (referred to as NI-RADS A) and ADC (using the best cutoff from receiver operating characteristic curve analysis, NI-RADS B) was documented in an Excel sheet to up- or downgrade existing classic American College of Radiology NI-RADS and calculate diagnostic accuracy.

RESULTS

Sixty-one malignant and 23 benign lesions included in the study were assigned American College of Radiology NI-RADS 2 (n = 33) and NI-RADS 3 (n = 51) categories. The recurrence rate was 90% (46/51) for NI-RADS three, 45% (15/33) for NI-RADS 2, and 73% (61/84) overall. T2WI signal morphology was intermediate in 45 subjects (53.5%) and restricted DWI in 54 (64.2%). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the American College of Radiology NI-RADS were the following: NI-RADS (75.4%, 78.3%, 90.1%, 54.5%, and 76.1%); NI-RADS A (79.1%, 81.2%, 91.9%, 59.1%, and 79.6%); and NI-RADS B (88.9%, 72.7%, 91.4%, 66.7%, and 85.1%), respectively.

CONCLUSIONS

Adding MR imaging diagnostic characteristics like T2WI, DWI, and ADC to the American College of Radiology NI-RADS improved diagnostic accuracy and sensitivity.

Antimicrobial Resistance of E Coli Causing Urinary Tract Infection in Bangladesh

Rapid spread of multidrug resistant microorganisms is a matter of great concern throughout the glove including Bangladesh. The objective was to identify the causative organisms for urinary tract infection (UTI) and their sensitivity patterns to antibiotics. This descriptive cross-sectional study was conducted on patients admitted with UTI (n=60) at a tertiary level hospital in Dhaka, Bangladesh from March 2019 to September 2019. Data were collected through clinical record reviews. Data of all these 60 cases were analyzed for socio-demographic characteristics. Of the 60 patients, culture and sensitivity report was available for 42 patients. Therefore, data were further analyzed for these 42 cases. Median age of patients was 35 years and 80% were female. The main organisms isolated from urine culture of UTI patients were E. coli (64%), Klebsiella (12%) and Enterococci species (10%). Susceptibility to antibiotics was analyzed only for E. coli (n=27) since the number of isolates of other organisms were small. E. coli was found to be resistant to most of the first- and second-line antibiotics, such as Amoxicillin (100%), Amoxyclav (72%), Co-trimoxazole (89%), Nalidixic acid (78%), Ceftazidim (94%), Ceftriaxone (73%), Cefuroxime (100%), Ciprofloxacin (59%), Cephotaxime (80%), Cefixime (100%) and Moxifloxacin (100%). E. coli was the predominant organism responsible for UTI and was resistant to most of the first- and second-line antibiotics. Immediate action is needed to develop empirical guideline for empirical management of UTI and establish surveillance system for monitoring.

P11.53 Genotype trumps phenotype: Oligodendroglioma and oligodendroglioma like tumors- A 1p19q fluorescence in situ hybridization based study at a tertiary referral centre in north India

BACKGROUND

The 2016 WHO update of CNS tumours defines oligodendroglioma as a diffusely infiltrating glioma with IDH 1 or IDH 2 mutation and co-deletion of chromosomal arms 1p and 19q. We evaluated the role of 1p19q testing by Fluorescence in situ hybridization (FISH) in the diagnosis and correct classification of CNS tumours in accordance with WHO 2016 classification and exclusion of morphological mimickers of oligodendrogliomas.

MATERIAL AND METHODS

A retrospective analysis of CNS tumours was carried out that were tested for 1p19q co-deletion by FISH over a period of fourteen months at our institute. Correlation with tumour morphology as well as other molecular tests (IDH mutation and MGMT) where available was then done. A tumour was considered to have 1p or 19q deletion when the 1p probe to 1q probe ratio (1p/1q) or the 19q probe to 19p probe ratio (19q/19p) was <0.80.

RESULTS

A total of 125 cases underwent FISH testing for 1p19q co-deletion over a period of last fourteen months at our institute with 74 male patients and 51 women. Thirty-eight of the 125 evaluated patients demonstrated 1p19q co-deletion on FISH. These included 25 oligodendrogliomas, 9 astrocytomas (Grade II/III) and 4 cases of oligoastrocytomas by morphology. Out of these cases, 21 cases had a co-existent IDH mutation, while two cases were IDH wild type and for 15 cases the status was unknown. Rest of the 87 patients were negative for 1p19q co-deletion and included cases of oligodendroglioma, other gliomas (pilocytic astrocytoma, oligoastrocytoma, glioblastoma) and few glioneuronal tumours (ganglioglioma, dysembryoplastic neuroepithelial tumour and central neurocytoma).

CONCLUSION

1. Analysis of 1p19q co-deletion by FISH plays an important role in correctly identifying cases of oligodendroglioma as shown in our study. This is important as it is both a predictive as well as prognostic biomarker 2. In cases with co-deletion but IDH wild type status, the 1p19q status should be confirmed by other methods such as comparative genomic hybridization to confirm the presence of whole chromosome loss.3. FISH analysis also helps in excluding morphologic mimics of oligodendroglioma such as glioneuronal tumours and pilocytic astrocytomas in young patients. 4. However, in a resource limited country like ours, a good morphological diagnosis should still form the basis for FISH and other molecular tests to avoid unnecessary testing.

Associations of obesity and lifestyle with the risk and mortality of bloodstream infection in a general population: a 15-year follow-up of 64 027 individuals in the HUNT Study

Background

Bloodstream infections (BSI) cause considerable morbidity and mortality, and primary prevention should be a priority. Lifestyle factors are of particular interest since they represent a modifiable target.

Methods

We conducted a prospective cohort study among participants in the population-based Norwegian HUNT2 Survey, where 64 027 participants were followed from 1995-97 through 2011 by linkage to prospectively recorded information on BSI at local and regional hospitals. The exposures were: baseline body mass index (BMI) measurements; and self-reported smoking habits, leisure time physical activity and alcohol intake. The outcomes were hazard ratios (HR) of BSI and BSI mortality.

Results

During 810 453 person-years and median follow-up of 14.8 years, 1844 (2.9%) participants experienced at least one BSI and 396 (0.62%) died from BSI. Compared with normal weight participants (BMI 18.5-24.9 kg/m2), the age- and sex-adjusted risk of a first-time BSI was 31% [95% confidence interval (CI) 14-51%] higher at BMI 30.0-34.9 kg/m2, 87% (95% CI 50-135%) higher at BMI 35.0-39.9 kg/m2 and 210% (95% CI 117-341%) higher at BMI ≥ 40.0 kg/m2. The risk of BSI mortality was similarly increased. Compared with never-smokers, current smokers had 51% (95% CI 34-70%) and 75% (95% CI 34-129%) higher risks of BSI and BSI mortality, respectively. Physically inactive participants had 71% (95% CI 42-107%) and 108% (95% CI 37-216%) higher risks of BSI and BSI mortality, respectively, compared with the most physically active.

Conclusions

Obesity, smoking and physical inactivity carry increased risk of BSI and BSI mortality.

Targeted Sequencing and Meta-Analysis of Preterm Birth

Understanding the genetic contribution(s) to the risk of preterm birth may lead to the development of interventions for treatment, prediction and prevention. Twin studies suggest heritability of preterm birth is 36–40%. Large epidemiological analyses support a primary maternal origin for recurrence of preterm birth, with little effect of paternal or fetal genetic factors. We exploited an “extreme phenotype” of preterm birth to leverage the likelihood of genetic discovery. We compared variants identified by targeted sequencing of women with 2–3 generations of preterm birth with term controls without history of preterm birth. We used a meta-genomic, bi-clustering algorithm to identify gene sets coordinately associated with preterm birth. We identified 33 genes including 217 variants from 5 modules that were significantly different between cases and controls. The most frequently identified and connected genes in the exome library were IGF1, ATM and IQGAP2. Likewise, SOS1, RAF1 and AKT3 were most frequent in the haplotype library. Additionally, SERPINB8, AZU1 and WASF3 showed significant differences in abundance of variants in the univariate comparison of cases and controls. The biological processes impacted by these gene sets included: cell motility, migration and locomotion; response to glucocorticoid stimulus; signal transduction; metabolic regulation and control of apoptosis.

Novel gene identified in an exome-wide association study of tanning dependence

Growing evidence suggests that some individuals may exhibit symptoms of dependence to ultraviolet light, a known carcinogen, in the context of tanning. Genetic associations with tanning dependence (TD) have not yet been explored. We conducted an exome-wide association study in 79 individuals who exhibited symptoms of TD and 213 individuals with volitional exposure to ultraviolet light, but who were not TD based on three TD scales. A total of 300 000 mostly exomic single nucleotide polymorphisms primarily in coding regions were assessed using an Affymetrix Axiom array. We performed a gene burden test with Bonferroni correction for the number of genes examined (P < 0.05/14 904 = 3.36 × 10(-6) ). One gene, patched domain containing 2 (PTCHD2), yielded a statistically significant P-value of 2.5 × 10(-6) (OR = 0.27) with fewer individuals classified as TD having a minor allele at this locus. These results require replication, but are the first to support a specific genetic association with TD.

Distribution profile of paraoxonase phenotypes among the Gujaratis

BACKGROUND:

Paraoxonase (PON1) can hydrolyze organophosphate pesticides (OP) and has a key role in the susceptibility of human in OP toxicity. The human-enzyme shows polymorphism and variations in the distribution profile of its phenotypes among different ethnic groups have been observed.

AIMS:

To see the distribution pattern of total PON1 activity in 45 healthy attendants of poisoning cases; 121 healthy unrelated farm-labours and 59 normal subjects of trauma.

MATERIALS AND METHODS:

The PON1 activities from serum/plasma samples of these healthy normal individuals were estimated with/without addition of 1M NaCl in order to determine salt-stimulated and basal activity. The PON 1 phenotypes were determined on the basis of percent activation of enzyme activity.

RESULTS:

Tri-modal distribution of basal PON1 activity was observed among all these individuals. 52.0% of the individuals belonged to Phenotype A, 46.6% to phenotype AB while 1.4% to Phenotype B with gene frequency of allele-A and allele-B being 0.753 and 0.247 respectively in excellent agreement with Hardy-Weinberg equilibrium.

CONCLUSION:

Maximum number of individuals belonged to phenotype-A (low PON1 activity) showing potential vulnerability towards Op-poisoning.

Self-expanding nitinol stents in recanalisation of long-length superficial femoral artery occlusions in patients with critical limb ischaemia

INTRODUCTION

This study aims to evaluate our experience with self-expanding nitinol stent- enabled recanalisation of long-length occlusions (30 cm or more) of the superficial femoral artery (SFA).

METHODS

573 patients underwent 842 lower limb interventions from August 2006 to December 2008. A retrospective review of patients undergoing recanalisation of long-length SFA occlusions with self-expanding nitinol stents and an evaluation of their patency and impact on limb salvage, were done.

RESULTS

22 patients (mean age 62.5 years, male: female ratio 11:11) underwent 22 long-length SFA stenting procedures. The spectrum of critical limb ischaemia included rest pain (five), ulcer (six) and gangrene (11). Length of occlusions varied from 30 cm to 45 cm (average length 36.4 cm). Five patients had stents placed through the ipsilateral popliteal artery approach, and the rest had stents placed through the femoral artery approach. All patients were followed up over an average duration of 12 months. One patient died due to associated medical conditions during this period. Six out of 21 (28.6 percent) of the stents thrombosed completely on one year follow-up. Of these, two patients underwent amputation, one patient had a bypass, and the stent in two patients were recanalised with balloon angioplasty. All remaining patent stents showed varying degrees of stenoses at one year. The overall limb salvage rate at one year following stent placement was 81 percent.

CONCLUSION

Our experience showed the beneficial result of long-length SFA stent placement with good limb salvage outcome. Repeat interventions may be required to maintain the patency of stents in these patients.

Use of complementary medicine (CAM) among women receiving chemotherapy for ovarian cancer: A comparison of attitudes between two patient populations

e20545

Background: CAM use in cancer patients (pts) is common. The aim of this study was to compare patterns of CAM use and attitudes to CAM among ovarian cancer (EOC) pts in Canada and Scotland. Methods: Patients receiving chemotherapy for EOC in Princess Margaret Hospital (PMH), Toronto and the Edinburgh Cancer Centre (ECC), Scotland, completed a survey on CAM taken within the previous month as well as a questionnaire assessing patient attitudes and perceptions of CAM. A comparison between the 2 patient populations and between CAM users and non-users was made. Results: 194 pts (100 ECC: 94 PMH) were enrolled on study. The use of CAM in PMH was significantly higher than in ECC (52% vs. 36%, p=0.02). Whilst both populations thought it important for their oncologist to be aware of CAM usage (86% PMH: 93% ECC), pts from PMH were less likely to inform their compared to pts from ECC (50% vs 81%, p=0.02). Patterns of CAM use differed between the 2 populations: Multivitamins were the most common CAM in both populations (31% PMH:13% ECC). They were not considered CAM for the purpose of analysis. Most commonly used CAM in PMH were Soy products (12%), vitamin C (10%) and Green Tea (9%); in ECC pts used Omega 3 and fish oil (9%), Evening Primrose (7%) and vitamin C (6%). Although the majority of CAM users in both populations found CAM to be helpful (57% PMH: 61% ECC) only a minority thought they would cure their cancer (18% PMH: 6% ECC), prevent its spread (31% PMH: 14% ECC) or prevent a recurrence (20% PMH: 11% ECC). Users more often felt CAM relieved symptoms (45% PMH: 42% ECC), boosted the immune system (55% PMH: 56% ECC) or improved their quality of life (43% PMH: 53% ECC). ECC CAM users were more likely than PMH users to concede that CAMs have side effects (39% vs 29%) or could impact the efficacy of conventional treatment (17% vs 6%). CAM users were more likely than non-users to agree with positive statements and to disagree with negative statements about CAM. Conclusions: CAM use is common among pts receiving chemotherapy for EOC. CAM use was more prevalent among North American pts than Scottish pts. Attitudes and patterns of CAM usage differ and are culturally sensitive. Oncologists need to be aware of this when initiating discussion about CAM with their patients during cancer treatment.

No significant financial relationships to disclose.

Further mapping of 10q26 supports strong association of HTRA1 polymorphisms with age-related macular degeneration

Age-related macular degeneration (AMD) is a complex disorder with genetic and environmental influences. The genetic influences affecting AMD are not well understood and few genes have been consistently implicated and replicated for this disease. A polymorphism (rs11200638) in a transcription factor binding site of the HTRA1 gene has been described, in previous reports, as being most significantly associated with AMD. In this paper, we investigate haplotype association and individual polymorphic association by genotyping additional variants in the AMD risk-associated region of chromosome 10q26. We demonstrate that rs11200638 in the promoter region and rs2293870 in exon 1 of HTRA1, are among the most significantly associated variants for advanced forms of AMD.

A variant of the HTRA1 gene increases susceptibility to age-related macular degeneration

Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss in the developed world and has a strong genetic predisposition. A locus at human chromosome 10q26 affects the risk of AMD, but the precise gene(s) have not been identified. We genotyped 581 AMD cases and 309 normal controls in a Caucasian cohort in Utah. We demonstrate that a single-nucleotide polymorphism, rs11200638, in the promoter region of HTRA1 is the most likely causal variant for AMD at 10q26 and is estimated to confer a population attributable risk of 49.3%. The HTRA1 gene encodes a secreted serine protease. Preliminary analysis of lymphocytes and retinal pigment epithelium from four AMD patients revealed that the risk allele was associated with elevated expression levels of HTRA1 mRNA and protein. We also found that drusen in the eyes of AMD patients were strongly immunolabeled with HTRA1 antibody. Together, these findings support a key role for HTRA1 in AMD susceptibility and identify a potential new pathway for AMD pathogenesis.

HTRA1 promoter polymorphism in wet age-related macular degeneration

Age-related macular degeneration (AMD), the most common cause of irreversible vision loss in individuals aged older than 50 years, is classified as either wet (neovascular) or dry (nonneovascular). Inherited variation in the complement factor H gene is a major risk factor for drusen in dry AMD. Here we report that a single-nucleotide polymorphism in the promoter region of HTRA1, a serine protease gene on chromosome 10q26, is a major genetic risk factor for wet AMD. A whole-genome association mapping strategy was applied to a Chinese population, yielding a P value of <10(-11). Individuals with the risk-associated genotype were estimated to have a likelihood of developing wet AMD 10 times that of individuals with the wild-type genotype.

Evidence for a putative bipolar disorder locus on 2p13-16 and other potential loci on 4q31, 7q34, 8q13, 9q31, 10q21-24, 13q32, 14q21 and 17q11-12

Bipolar disorder (BP) is a severe and common psychiatric disorder characterized by extreme mood swings. Family, twin and adoption studies strongly support a genetic component. The mode of inheritance is complex and likely involves multiple, as yet unidentified genes. To identify susceptibility loci, we conducted a genome-wide scan with 343 microsatellite markers in one of the largest, well-characterized pedigree samples assembled to date (373 individuals in 40 pedigrees). To increase power to detect linkage, scan statistics were used to examine the logarithm of odds (lod) scores based on evidence at adjacent chromosomal loci. This analysis yielded significant evidence of linkage (genome-wide P&<0.05) for markers on 2p13-16. Standard linkage analysis was also supportive of linkage to 2p13-16 (lod=3.20), and identified several other interesting regions: 4q31 (lod=3.16), 7q34 (lod=2.78), 8q13 (lod=2.06), 9q31 (lod=2.07), 10q24 (lod=2.79), 13q32 (lod=2.2), 14q21 (lod=2.36) and 17q11-12 (lod=2.75). In this systematic, large-scale study, we identified novel putative loci for BP (on 2p13-16, 8q13 and 14q21) and found support for previously proposed loci (on 4q31, 7q34, 9q31, 10q21-24, 13q32 and 17q11-12). Two of the regions implicated in our study, 2p13-14 and 13q32, have also been linked to schizophrenia, suggesting that the two disorders may have susceptibility genes in common.

Linkage of left ventricular contractility to chromosome 11 in humans: The HyperGEN Study

Impaired left ventricular (LV) contractility is a major cause of cardiovascular death, especially congestive heart failure. The identification of susceptibility genes that contribute to impaired LV contractility may uncover mechanisms underlying LV contractile impairment and the development of congestive heart failure. The Hypertension Genetic Epidemiology Network (HyperGEN) collected echocardiographic measurements of myocardial contractility in a large biethnic sample of hypertensive siblings (390 blacks and 398 whites in 179 and 165 sibships, respectively). All participants expressed hypertension before age 60 years, and the mean age of siblings was 52 years in blacks and 61 years in whites. We adjusted myocardial contractility for gender, age, and age(2), and we calculated standardized residuals separately for men and women in both ethnic groups. We conducted multipoint variance components linkage analysis using GENEHUNTER2 and 387 anonymous markers (CHCL8 marker set). We found evidence for significant linkage to a microsatellite marker, D11S1993 (lod, 3.93 in blacks), approximately 54 cM from the tip of the short arm of chromosome 11, that accounted for 72% of the phenotypic variation in LV contractility. A chromosome 22 locus showed suggestive evidence for linkage (lod, 2.83 in whites and 1.15 in blacks). The chromosome 11 peak coincides with the region containing myosin-binding protein C. Mutations in this gene are linked to familial hypertrophic cardiomyopathy. Our results show strong evidence for linkage of a region of chromosome 11 with LV contractility in blacks and suggest that an important gene for impaired LV contractility is harbored in this region.

N-acetyltransferase activity--a susceptibility factor in human bladder carcinogenesis

A higher proportion of slow acetylator phenotypes has previously been found among bladder cancer patients. In the present study carried out among 77 male bladder cancer patients and 80 non-cancer controls, 59.74% of the patients and 35% of the controls were slow acetylator phenotypes (p < 0.01). The odds of developing bladder cancer was also observed to be significantly higher among smokers than non-smokers (p < 0.01). The findings suggest that slow N-acetyl phenotype is a susceptibility factor in bladder carcinogenesis.

In vitro micropropagation of Acacia nilotica subsp. indica Brenan via cotyledonary nodes

Cotyledonary node explants of Acacia nilotica subspecies indica Brenan, differentiated multiple shoots on Gamborg et al.' s medium (B5, Gamborg et al. 1968) supplemented with cytokinins like N(6)-benzyladenine, 6-(γ, γ-Dimethylallylamino)-purine, kinetin or zeatin. Of the four, BA supported maximum multiple shoot differentiation; the highest average number of shoots (6.3) per expiant was in 1.5 mg/l. The number of shoots was further enhanced by (i) using nodal explants of in vitro regenerated shoots as microcuttings, and (ii) repeated subculture of the original expiants (stumps) on the same medium after excising the shoots. Thus, over seven hundred shoots could be obtained from a single cotyledonary node explant. Individual shoots, when transferred to 2 mg/l indole-3-acetic acid augmented medium organised healthy roots in 100% cultures. Such test tube grown plantlets have been successfully transferred to soil, where they grow well up to eight weeks.

Cardiac toxicity following short-term exposure to methomyl in spraymen and rabbits

A health surveillance study in 22 healthy spraymen showed significant T-wave changes (including inversion) in most of the limb leads and chest leads following 5 d exposure to methomyl, a carbamate pesticide. Significant changes in plasma cholinesterase and lactic dehydrogenase activities were also noticed. The ECG changes could be reproduced in rabbits and were dose dependent. This type of ECG change following exposure to a carbamate compound is reported for the first time in occupationally-exposed subjects. The study results indicate that these changes are probably directly related to methomyl rather than its toxicity through cholinesterase inhibition. The significance of these changes remain to be investigated.

Benzidine and its acetylated metabolites in the urine of workers exposed to Direct Black 38

Urine samples of workers in a small-scale unit manufacturing Direct Black 38 were analyzed by high-pressure liquid chromatography for the presence of benzidine and mono and diacetyl benzidine. Acetylated metabolites were found in all the urine samples, and benzidine was found in all except two. Two workers excreted very high levels of benzidine and its metabolites in their urine. This study highlights the potential risk of bladder cancer in such units of developing countries where manufacture of benzidine-based dyes is yet to be regulated.

Urinary excretion of benzidine in relation to the acetylator status of occupationally exposed subjects

Twenty-four male workers engaged in the manufacture of benzidine dihydrochloride for 1-4 years were included in this study. Urinary levels of free benzidine were estimated by high-pressure liquid chromatography in all the workers. Acetylator status of the workers was determined with sulphamethazine. There was substantial absorption of benzidine over an 8-h work shift. A significant correlation was observed between the rate of sulphamethazine acetylation and urinary excretion of free benzidine.