[CT perfusion combined with energy spectrum imaging to evaluate the short-term efficacy of bronchial arterial chemoembolization for lung cancer].

Objective: To evaluate the clinical value of dynamic volumetric CT perfusion combined with energy spectrum imaging in bronchial arterial chemoembolization (BACE) in patients with lung cancer. Methods: The data of 31 patients with lung cancer confirmed by pathology and treated with BACE in Lishui Central Hospital from January 2018 to February 2022 were retrospectively collected, including 23 men and 8 women, aged 31-84 (67) years. All patients received perfusion scans of lesion sites within 1 week before surgery and 1 month after surgery. We collected and compared the changes in preoperative and postoperative perfusion parameters such as blood flow (BF), blood volume (BV), mean through time (MTT), permeability surface (PS) and energy spectrum parameters including arterial phase CT value (CTA), venous phase CT value (CTV), arterial phase iodine concentration (ICA), venous phase of iodine concentration (ICV), arterial standardization iodine concentration (NICA), and intravenous standardized iodine concentration (NICV) to confirm the significance of these parameters in evaluating the short-term efficacy of BACE in the treatment of advanced lung cancer. Data normality was tested using the Kolmogorov-Smirnov test and normally distributed measurement data are expressed here as mean ± standard deviation; the independent-samples t-test was used for comparisons between two groups. The measurement data that were not normally distributed are expressed as median (interquartile interval) [M (Q1, Q3)], and the comparison between the two groups used the Kruskal-Wallis test. Count data are expressed as cases (%), and comparisons between groups used the χ2 test. Results: The objective response rate (ORR) and disease control rate (DCR) at 1 month after BACE were 54.8% (17/31) and 96.8% (30/31), respectively. CT perfusion parameters and energy spectrum parameters of patients before and after BACE treatment were compared. The results showed that BF, BV, MTT, ICA, ICV and NICV were significantly decreased after BACE treatment compared with before treatment, and the differences were statistically significant[58.06 (40.47,87.22) vs.23.57(10.92, 36.24) ml·min-1·100g-1,3.33(2.86,6.09) vs.2.12(1.96,3.61)ml/100g,2.70(2.19,3.88) vs.1.53 (1.12,2.25)s, 3.51 (3.11,4.14)vs.1.74 (1.26,2.50)mg/ml,2.00 (1.30,2.45) vs.1.32(0.92,1.76)mg/ml,0.51(0.42,0.57) vs.0.33(0.23,0.39)](all P<0.05). At the same time, compared with the non-remission group, the study results showed that the difference of parameters in remission group before and after BACE was more obvious, including ΔBF, ΔBV, ΔMTT, ΔPS, ΔCTA, ΔCTV, ΔICA, ΔICV, ΔNICA, ΔNICV were significantly increased, and the difference was statistically significant [36.82(32.38, 45.34) vs.9.50(-1.43, 12.34) ml·min-1·100g-1,4.46(2.52, 5.79) vs.0.22(-0.76, 4.09) ml/100g,4.22(2.25, 6.77) vs.0.43(-2.53, 1.88) s,10.07 (2.89, 13.13) vs.-2.01(-6.77, 4.28) ml·min-1·100g-1,14.22(11.88, 20.57) vs.4.18(-5.25, 6.37) HU, 34.6(14.88, 43.15) vs.11.60(0.26, 25.05) HU,0.95(0.54, 1.47) vs.0.11(0.20, 0.59) mg/ml,1.57(1.10, 2.38) vs. 0.26(-0.21, 0.63) mg/ml,0.05(0.03, 0.08) vs.-0.02(-0.04, 0.01),0.18(0.13, 0.21)vs. 0.11(-0.06, 0.16)](all P<0.05). Conclusions: CT perfusion combined with spectral imaging could effectively evaluate the changes in tumor vascular perfusion in patients with advanced lung cancer before and after BACE treatment, which has important value in judging the short-term efficacy after treatment.

[Construction of prediction model combined dual-energy CT quantitative parameters and conventional CT features for assessing the Ki-67 expression levels in invasive breast cancer].

Objective: To develop a model combined with dual-energy CT quantitative parameters and conventional CT features for evaluating the expression level of Ki-67 in invasive breast cancer. Methods: A total of 191 patients with histologically confirmed invasive breast cancer in Lishui Central Hospital from March 2019 to December 2020, were retrospectively enrolled, all of them were females, aged from 25 to 77 (53.2±11.3) years. All patients underwent preoperative non-contrast chest and contrast-enhanced Dual energy CT scans, and the normalized iodine concentration (NIC) of lesions on arterial and venous phase, spectral curve slope (λHU), and normalized effective atomic number (nZeff) were measured and calculated, and their conventional CT characteristics were assessed. According to the results of immunohistochemistry (IHC), the patients were divided into Ki-67 high expression group (n=129 patients) and low expression group (n=62 patients) level. The differences in clinical data, conventional CT characteristics and dual-energy CT quantitative parameters between the two groups were analyzed. The receiver operating characteristic curve (ROC) curve was conducted to assess the efficacy of each individual model and joint model in evaluating Ki-67 expression levels, and the area under the curve (AUC), sensitivity, specificity, and accuracy were calculated, respectively. Results: In the analysis of CT features, the longest diameter, shape and enhancement pattern of the tumor were significantly difference between the two groups (all P<0.05). The NIC, nZeff on the arterial phase and NIC, nZeff and λHU [M(Q1,Q3)] on the venous phase were higher in the high Ki-67 expression group compared to the low expression group [0.13 (0.12, 0.16) vs 0.11 (0.08, 0.14), 0.71 (0.70, 0.75) vs 0.70 (0.67, 0.72), 0.40 (0.32, 0.48) vs 0.23 (0.17, 0.32), 3.10 (2.58, 3.63) vs 2.86 (2.19, 3.48), 0.88 (0.85, 0.92) vs 0.85 (0.84, 0.86), all P<0.05]. The logistic regression model, which integrated significant conventional CT features and dual-energy CT quantitative parameters, demonstrated the highest diagnostic performance for assessing Ki-67 expression levels, with an AUC of 0.924, sensitivity of 88.37%, specificity of 83.87%, and accuracy of 86.91%; the AUC of the dual-energy CT parameter model was 0.908, sensitivity of 82.17%, specificity of 88.71%, and accuracy of 84.29%. Though the diagnostic efficacy was no significant difference (P=0.238), both models showed superior to the conventional CT feature model (all P<0.001). Conclusion: A dual-energy CT quantitative parameter combined with a conventional CT feature model was successfully constructed, which has a good evaluation performance on the expression level of Ki-67 in invasive breast cancer.

Sinus tarsi approach (STA) versus extensile lateral approach (ELA) for treatment of closed displaced intra-articular calcaneal fractures (DIACF): A meta-analysis.

INTRODUCTION: Our aim was to compare the effect of sinus tarsi approach (STA) vs extensile lateral approach (ELA) for treatment of closed displaced intra-articular calcaneal fractures (DIACF) is still being debated. MATERIALS AND METHODS: A thorough research was carried out in the MEDLINE, EMBASE and Cochrane library databases from inception to December 2016. Only prospective or retrospective comparative studies were selected in this meta-analysis. Two independent reviewers conducted literature search, data extraction and quality assessment. The primary outcomes were anatomical restoration and prevalence of complications. Secondary outcomes included operation time and functional recovery. RESULTS: Four randomized controlled trials involving 326 patients and three cohort studies involving 206 patients were included. STA technique for DIACFs led to a decline in both operation time and incidence of complications. There were no significant differences between the groups in American Orthopedic Foot and Ankle Society scores, nor changes in Böhler angle. CONCLUSIONS: This meta-analysis suggests that STA technique may reduce the operation time and incidence of complications. In conclusion, STA technique is reasonably an optimal choice for DIACF.

The Role of Apoptotic Factors in Assessing Progression of Periodontal Disease.

BACKGROUND: The mechanisms responsible for periodontal disease progression remain unclear. However, recent studies suggest that apoptosis may be one mechanism underlying the pathophysiology of periodontal disease progression. This pilot study is the 3 month follow-up of our published baseline study on the presence of apoptotic factors in serum, saliva, and gingival crevicular fluid (GCF) and their association with periodontal disease severity and activity. METHODS: GCF samples were obtained from 37 adult patients with chronic periodontitis (CP) and 7 healthy controls. Clinical measurements, including probing depth (PD), clinical attachment level (CAL), and radiographs, were used to evaluate data by sites and to classify patients into healthy, mild, and moderate/severe CP groups. Enzyme-linked immunosorbent assays were used to measure apoptosis or DNA fragmentation levels in GCF. Western immunoblotting was used to detect several apoptotic proteins, Fas, FasL, sFasL, and caspase-3 expression and its cleavage products in GCF. RESULTS: At the patient level clinical and apoptotic measurements change minimally over time. At the site level, DNA fragmentation levels increase with increasing PDs at 3 months and baseline. Apoptotic protein expression exhibits increasing trends with increasing PDs at baseline and 3 months. FasL and Active FasL show a high specificity and PPV; low sensitivity and NPV. Caspase-3 products (ProCas35K and Active Cas) show a high PPV with moderate to high specificity; low sensitivity and NPV. ProCas70K shows a high PPV with moderate to high sensitivity; low specificity and NPV. CONCLUSION: Factors associated with apoptosis show minimal changes in expression in periodontitis groups in comparison to a healthy group over a short time interval (3 months). However, at the site level, apoptotic factors (DNA fragmentation and apoptotic proteins) exhibit significant increases or increasing trends with increasing PDs at any time point examined (baseline or 3 months). Several of these apoptotic factors also exhibit a high sensitivity and high positive predictive value. Thus, apoptotic molecules may be helpful biomarkers of disease status at any point in time.

Reconstructive procedures for treating peri-implantitis: a systematic review.

This review aimed at evaluating the effectiveness of reconstructive procedures for treating peri-implantitis. Searches of electronic databases and cross-referencing were performed for human comparative clinical trials with ≥ 10 implants for ≥ 12 months of follow-up, reporting radiographic defect fill and at least one of the following parameters: probing depth reduction, clinical attachment level gain, bleeding on probing reduction, and mucosal recession. The searches retrieved 430 citations. Only 1 randomized controlled trial was identified, which compared reconstructive therapy and open flap debridement. Case series studies were also included to evaluate the overall performance of the reconstructive procedures. Twelve studies were finally included. Meta-analysis revealed that the weighted mean radiographic defect fill was 2.17 mm (95% confidence interval [CI]: 1.46-2.87 mm), probing depth reduction was 2.97 mm (95% CI: 2.38-3.56 mm), clinical attachment level gain was 1.65 mm (95% CI: 1.17-2.13 mm), and bleeding on probing reduction was 45.8% (95% CI: 38.5%-53.3%). Great variability in reparative outcomes was found, attributed to patient factors, defect morphology, and reconstructive agents used. Currently, there is a lack of evidence for supporting additional benefit of reconstructive procedures to the other treatment modalities for managing peri-implantitis.

Differential expression patterns of growth-related microRNAs in the skeletal muscle of Nile tilapia (Oreochromis niloticus).

MicroRNA (miRNA) are a class of small, single-stranded, non-coding RNA that regulate mRNA expression at the post-transcriptional level and play important roles in many fundamental biological processes. There is emerging evidence that miRNA are critical regulators of widespread cellular functions, such as differentiation, proliferation, and migration. At present, little is known about miRNA expression profiles related to skeletal muscle growth in aquatic organisms. This study aimed to investigate the phenotypic variation in the body growth of the Nile tilapia (Oreochromis niloticus) and to identify and quantify the differential expression levels of selected growth-related transcriptomic miRNA in the skeletal muscle of this fish. To this end, we performed next-generation sequencing to define the full miRNA transcriptome in muscle tissue from Nile tilapia and to detect differentially expressed miRNA between 2 strains of Nile tilapia. These tilapia strains exhibited significant (P < 0.05) phenotypic variation with respect to growth-related traits (body length and BW), mitochondrial DNA (mtDNA) haplotype diversity, and the differential expression of selected growth-related genes. The results obtained from the transcriptome analysis and real-time quantitative reverse transcription PCR (qRT-PCR) revealed significant differences in miRNA expression between fast-growing and control strains of tilapia. Digital gene expression (DGE) profiling was performed based on the obtained read abundance, and we identified down-regulated miRNA, including let-7j, miR-140, miR-192, miR-204, miR-218a, miR-218b, miR-301c, and miR-460, and up-regulated miRNA, including let-7b, let-7c, miR-133, miR-152, miR-15a, miR-193a, miR-30b, and miR-34, associated with body growth in tilapia. These results were further validated using real-time qRT-PCR and microarray profiling. In summary, the up- and down-regulation of miRNA involved in the GH/IGF-1 axis signaling pathway suggests that the differential expression levels of growth-related miRNA may serve as molecular markers that are predictive of specific functional and diagnostic implications. The obtained data on genetic polymorphisms in miRNA-target interactions are particularly useful for Nile tilapia breeding programs.

Analysis of community structure of a microbial consortium capable of degrading benzo(a)pyrene by DGGE.

A microbial consortium was obtained by enrichment culture of sea water samples collected from Botan oil port in Xiamen, China, using the persistent high concentration of a mixture of polycyclic aromatic hydrocarbons enrichment strategy. Denaturing gradient gel electrophoresis (DGGE) was used to investigate the bacterial composition and community dynamic changes based on PCR amplification of 16S rRNA genes during batch culture enrichment. Using the spray-plate method, three bacteria, designated as BL01, BL02 and BL03, which corresponded to the dominant bands in the DGGE profiles, were isolated from the consortium. Sequence analysis showed that BL01, BL02 and BL03 were phylogenetically close to Ochrobactrum sp., Stenotrophomonas maltophilia and Pseudomonas fluorescens, respectively. The degradation of benzo(a)pyrene (BaP), a model high-molecular-weight polycyclic aromatic hydrocarbon (HMW PAH) compound was investigated using individual isolates, a mixture of the three isolates, and the microbial consortium (BL) originally isolated from the oil port sea water. Results showed that the order of degradative ability was BL>the mixture of the three isolates>individual isolates. BL degraded 44.07% of the 10 ppm BaP after 14 days incubation, which showed the highest capability for HMW PAH compound degradation.Our results revealed that this high selective pressure strategy was feasible and effective in enriching the HMW PAH-degraders from the original sea water samples.

Bacterial and archaeal assemblages in sediments of a large shallow freshwater lake, Lake Taihu, as revealed by denaturing gradient gel electrophoresis.

AIMS: To explore the association of microbial community structure with the development of eutrophication in a large shallow freshwater lake, Lake Taihu. METHODS AND RESULTS: The bacterial and archaeal assemblages in sediments of different lake areas were analysed using denaturing gradient gel electrophoresis (DGGE) of amplified 16S rDNA fragments. The bacterial DGGE profiles showed that eutrophied sites, grass-bottom areas and relatively clean sites with a eutrophic (albeit dredged) site are three respective clusters. Fifty-one dominant bacterial DGGE bands were detected and 92 corresponding clones were sequenced, most of which were affiliated with bacterial phylotypes commonly found in freshwater ecosystems. Actinobacteria were detected in the centre of the lake and not at eutrophied sites whereas the opposite was found with respect to Verrucomicrobiales. Twenty-five dominant archaeal DGGE bands were detected and 31 corresponding clones were sequenced, most of which were affiliated with freshwater archaeal phylotypes. CONCLUSIONS: The bacterial community structures in the sediments of different areas with similar water quality and situation tend to be similar in Taihu Lake. SIGNIFICANCE AND IMPACT OF THE STUDY: This study may expand our knowledge on the relationship between the overall microbial assemblages and the development of eutrophication in the shallow freshwater lake.

Interleukin-2 confers cardioprotection by inhibiting mitochondrial permeability transition pore.

In the present study, we determined whether interleukin-2 (IL-2) confers cardioprotection by inhibiting mitochondria permeability transition pore (MPTP) opening. In isolated rat hearts subject to 30 min ischemia and 120 min reperfusion (IR), IL-2 (50 U/ml) decreased the infarct size and LDH release, effects blocked by a selective kappa-opioid receptor antagonist, Nor-BNI (5 microM) or an opener of MPTP, atractyloside (Atr, 20 microM). In isolated ventricular myocytes subjected to anoxia and reoxygenation (AR), which reduced both the amplitude of the electrically induced [Ca2+]i transient and diastolic [Ca2+]i, IL-2 attenuated the AR-induced alterations and their effects were abolished by Atr. In addition, IL-2 attenuated the reduction in calcein fluorescence in myocytes subject to AR and reduced calcium-induced swelling in mitochondria of rat hearts subjected to IR, which were similar to effect of inhibitor of MPTP. The observations indicated that IL-2 confers cardioprotection by inhibiting the MPTP opening.

Effects of interleukin-2 on the mechanical restitution and post-rest contraction in rat ventricular papillary muscle.

To determine whether application of interleukin-2 (IL-2) alters function of sarcoplasmic reticulum (SR), we measured mechanical restitution and post-rest potentiation (PRP) in isolated rat papillary muscles. Mechanical restitution curves were constructed by interpolating extrasystoles at different test intervals following a train of steady state beats. In control group, the maximal PRP was reached after 60-120s of rest and the maximal potentiation factor was 2.36 +/- 0.23. IL-2 at 200 U/ml decreased the steady-state force of contraction to 56.4 +/- 7.2% of pre-drug control. But the time constant of recovery of steady-state force was not altered after IL-2. IL-2 decreased PRP at all intervals, shifted the potentiation curve parallel to lower values. But the potentiation was enhanced when compared with pre-rest control value in the presence of IL-2. In papillary muscle treated with IL-2, the onset of maximal PRP was delayed and the potentiation factor after 300s was 4.72 +/- 0.58 times that at the steady-state. Recirculation fraction of calcium calculated from the decay of PRP was 0.78 +/- 0.09 in control and 0.59 +/- 0.08 after IL-2 treatment. We conclude that IL-2 decreases the function of SR, which suggests that an impaired function of SR may contribute to the negative inotropic effect of IL-2.

Negative inotropic effect of interleukin-2 in the isolated ventricular myocytes: role of NO/sGC pathway.

The present study is to investigate the effect and possible mechanism of interleukin-2 (IL-2) on the cell contractility in isolated rat cardiomyocytes. Ventricular myocytes were isolated from adult male Sprague-Dawley rats. Contractile responses were evaluated by use of the video tracking system. Contractile properties analyzed in cells electrically stimulated at 0.2Hz included peak velocity of cell shortening (+dL/dtmax), peak velocity of cell relengthening (-dL/dtmax), contraction amplitude (dL) and end-diastolic cell length. Calcium transients of ventricular myocytes were determined by the spectrofluorometric techniques. IL-2 (2.0, 10, 50, 200 and 1000 U/ml) exhibited a dose-dependent inhibition in +dL/dtmax, -dL/dtmax, dL and end-diastolic cell length. Pretreatment with the nitric oxide synthase inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME, 100 microM) and 1H-[1,2,4]oxadiazolo[4,3a]quinoxalin-1-one (ODQ, soluble guanylyl cyclase inhibitor) blocked IL-2-induced inhibition of the contractility. IL-2 at 200 U/ml decreased the amplitude of the [Ca2+]i transient. Pretreatment with the L-NAME or ODQ abolished IL-2-induced inhibition of amplitude of the calcium transient. We conclude that the depressant effect of IL-2 on the contraction and calcium transient of isolated ventricular myocytes is mediated by nitric oxide/soluble guanylyl cyclase pathway.

Influence of interleukin-2 on Ca2+ handling in rat ventricular myocytes.

In the present study, we examined the effect of interleukin-2 (IL-2) on cardiomyocyte Ca(2+) handling. The effects of steady-state and transient changes in stimulation frequency on the intracellular Ca(2+) transient were investigated in isolated ventricular myocytes by spectrofluorometry. In the steady state (0.2 Hz) IL-2 (200 U/ml) decreased the amplitude of Ca(2+) transients induced by electrical stimulation and caffeine. At 1.25 mM extracellular Ca(2+) concentration ([Ca(2+)](o)), when the stimulation frequency increased from 0.2 to 1.0 Hz, diastolic Ca(2+) level and peak intracellular Ca(2+) concentration ([Ca(2+)](i)), as well as the amplitude of the transient, increased. The positive frequency relationships of the peak and amplitude of [Ca(2+)](i) transients were blunted in the IL-2-treated myocytes. The effect of IL-2 on the electrically induced [Ca(2+)](i) transient was not normalized by increasing [Ca(2+)](o) to 2.5 mM. IL-2 inhibited the frequency relationship of caffeine-induced Ca(2+) release. Blockade of sarcoplasmic reticulum (SR) Ca(2+)-ATPase with thapsigargin resulted in a significant reduction of the amplitude-frequency relationship of the transient similar to that induced by IL-2. The restitutions were not different between control and IL-2 groups at 1.25 mM [Ca(2+)](o), which was slowed in IL-2-treated myocytes when [Ca(2+)](o) was increased to 2.5 mM. There was no difference in the recirculation fraction (RF) between control and IL-2-treated myocytes at both 1.25 and 2.5 mM [Ca(2+)](o). The effects of IL-2 on frequency relationship, restitution, and RF may be due to depressed SR functions and an increased Na(+)-Ca(2+) exchange activity, but not to any change in L-type Ca(2+) channels.

Molecular cloning and characterization of fengycin synthetase gene fenB from Bacillus subtilis.

A fengycin synthetase gene, fenB, has been cloned and sequenced. The protein (FenB) encoded by this gene has a predicted molecular mass of 143.6 kDa. This protein was overexpressed in Escherichia coli and was purified to near homogeneity by affinity chromatography. Experimental results indicated that the recombinant FenB has a substrate specificity toward isoleucine with an optimum temperature of 25 degrees C, an optimum pH of 4.5, a Km value of 922 microM, and a turnover number of 236 s(-1). FenB also consists of a thioesterase domain, suggesting that this protein may be involved in the activation of the last amino acid of fengycin.

Ocular and dermal irritation studies of some quaternary ammonium compounds.

The primary ocular and dermal irritations of four quaternary ammonium compounds, namely cetylpyridinium chloride (CPC), stearylphenylethyldimethylammonium tosylate (SPDAT), dimethyldistearylammonium bisulfate (DDABS) and tri(N-butyl)benzylammonium 4-hydroxynapththalene-1-sulfonate (TBAHNS), were studied. Both CPC and SPDAT were extremely or severely irritating to the eyes of the test animals, whereas DDABS and TBAHNS were mildly or minimally irritating. Both CPC and SPDAT were also severely or extremely irritating to the skin of the test animals, while DDABS and TBAHNS were non-irritating. These quaternary ammonium compounds have little similarity in chemical structure and possess different solubilities. CPC is very soluble in both lipid and water; SPDAT is very soluble in lipid but only slightly soluble in water; and DDABS and TBAHNS are poorly soluble in either lipid or water. The irritancy of these compounds is likely to be related to their solubility, in addition to the cationic characteristics. It appears that not all quaternary ammonium compounds in this study are irritants. Those that are not soluble are not expected to be absorbed in eye/skin tissues and thus irritation reactions will not take place. The use of in vitro alternatives should be considered when assessing the ocular and dermal irritancy potential of water- and lipid-soluble quaternary ammonium compounds.

Mutagenicity studies on two triphenylmethane dyes, bromophenol blue and tetrabromophenol blue.

Bromophenol blue and tetrabromophenol blue are two triphenylmethane dyes. Triphenylmethane derivatives and their structurally related compounds, such as fluoresceins and xathenes, are widely used as industrial dyes for foods, drugs, cosmetics, textiles, printing inks or laboratory indicators. Since a number of these types of dyes have been reported to be genotoxic, safety concerns on these two dyes of interest have been raised. Consequently, a battery of genetic toxicology assays, including the Ames Salmonella/microsome assay, L5178Y TK+/- mouse lymphoma assay, mouse micronucleus test and mitotic recombination assay with yeast Saccharomyces cerevisiae strain D5, has been performed on each of the two dyes. The results of the evaluations indicate that both bromophenol blue and tetrabromophenol blue were not active and can be considered non-genotoxic for the three genetic endpoints assessed (gene mutation, chromosome aberrations and primary DNA damage). Genetic activities in some structurally related compounds of these dyes have been reported but may be attributed to the presence of mutagenic impurities rather than the compound itself.

Acute inhalation toxicity of cetylpyridinium chloride.

Cetylpyridinium chloride (CPC) is a quaternary ammonium salt and cationic surfactant. It has been used as a biocide in personal hygiene products and a charge control additive in some reprographic toners. CPC is orally toxic to rats, mice and rabbits and can cause severe eye irritation. Acute inhalation toxicity studies of CPC and other quaternary ammonium salts have not, however, been reported. Groups of five rats per sex were exposed to aerosols containing 0 (control), 0.05, 0.07, 0.13 and 0.29 mg CPC/litre for 4 hr and observed for toxicity and ocular effects for 14 days thereafter. All animals were subjected to autopsy and the eyes were examined microscopically. The LC50 (sexes combined) of CPC was 0.09 mg/litre with upper and lower 95% confidence limits of 0.13 and 0.07 mg/litre, respectively. Clinical signs of toxicity included weight loss, nasal discharge, chromodacryorrhoea, respiratory difficulty and eye irritation, and all these non-lethal effects were reversible. Acute inflammation of the cornea, iris and/or aqueous humour were found in one, seven and four of 10 rats exposed to 0.07, 0.13 and 0.29 mg CPC/litre, respectively. Corneal epithelial hyalinization, without evidence of ongoing inflammation, was found in three additional rats among the 10 exposed to 0.29 mg CPC/litre.

Structure-activity relationship studies on the mutagenicity of some azo dyes in the Salmonella/microsome assay.

Analogs of Direct Black 19 and Direct Black 38 were synthesized and tested in the Salmonella/microsome assay. Those dyes which gave positive responses in strains TA98 and TA1538 would be expected to be metabolized to p-phenylenediamine by the liver microsomal enzymes (S9). Pure p-phenylenediamine is non-mutagenic in this assay but becomes mutagenic after it is oxidized. Thus the positive response of our synthetic azo compounds are most likely due to the formation of oxidized p-phenylenediamine. Modification of the moieties that can be metabolized to p-phenylenediamine by sulfonation, carboxylation or copper complexation eliminated the mutagenic responses.