Evaluation of metallothionein and p53 expression as potential prognostic markers for laryngeal squamous cell carcinoma

The aim of the study was to determine the contribution of metallothionein (MT) and p53 expression in predicting laryngeal squamous cell carcinoma (SCC) recurrence. This was a retrospective study in which MT and p53 immunopositive staining in 32 laryngeal SCC paraffin-embedded sections, were correlated with clinical recurrence. Recurrence was observed in 8 cases with MT expression (42.1%) and 1 case with no expression (7.7%). Moderate and strong MT expression was associated with 14.3% and 58.3% recurrence, respectively. Recurrence was similar for both p53-negative (21.1%) and p53-positive (27.3%) groups. One third of the patients expressing both p53 and MT simultaneously had recurrence. Thus, the combined expression of p53 and MT did not improve the predictive value for recurrence compared to MT alone. MT over-expression may be an independent risk factor for laryngeal SCC recurrence.

In vitro and human testing strategies for skin irritation

Prior to the manufacture, transport, and marketing of chemicals or products, it is critical to assess their potential for skin toxicity (corrosion or irritation), thereby protecting the worker and consumer from adverse skin effects due to intended or accidental skin exposure. Traditionally, animal testing procedures have provided the data needed to assess the more severe forms of skin toxicity, and current regulations may require animal test data before permission can be obtained to manufacture, transport, or market chemicals or the products that contain them. In recent years, the use of animals to assess skin safety has been opposed by some as inhumane and unnecessary. The conflicting needs of the industrial toxicologist to (1) protect human safety, (2) comply with regulations, and (3) reduce animal testing have led to major efforts to develop alternative, yet predictive, test methods. A variety of in vitro skin corrosion test methods have been developed and several have successfully passed initial international validation. These have included skin or epidermal equivalent assays that have been shown to distinguish corrosive from noncorrosive chemicals. These skin/epidermal equivalent assays have also been modified and used to assess skin irritation potential relative to existing human exposure test data. The data show a good correlation between in vitro assay data and different types of human skin irritation data for both chemicals and consumer products. The effort to eliminate animal tests has also led to the development of a novel human patch test for assessment of acute skin irritation potential. A case study shows the benefits of in vitro and human skin irritation tests compared to the animal tests they seek to replace, and strategies now exist to adequately assess human skin irritation potential without the need to rely on animal test methods.

Prediction of eye irritation from organic chemicals using membrane-interaction QSAR analysis

Eye irritation potency of a compound or mixture has traditionally been evaluated using the Draize rabbit-eye test (Draize et al., 1944). In order to aid predictions of eye irritation and to explore possible corresponding mechanisms of eye irritation, a methodology termed "membrane-interaction QSAR analysis" (MI-QSAR) has been developed (Kulkarni and Hopfinger 1999). A set of Draize eye-irritation data established by the European Center for Ecotoxicology and Toxicology of Chemicals (ECETOC) (Bagley et al., 1992) was used as a structurally diverse training set in an MI-QSAR analysis. Significant QSAR models were constructed based primarily upon aqueous solvation-free energy of the solute and the strength of solute binding to a model phospholipid (DMPC) monolayer. The results demonstrate that inclusion of parameters to model membrane interactions of potentially irritating chemicals provides significantly better predictions of eye irritation for structurally diverse compounds than does modeling based solely on physiochemical properties of chemicals. The specific MI-QSAR models reported here are, in fact, close to the upper limit in both significance and robustness that can be expected for the variability inherent to the eye-irritation scores of the ECETOC training set. The MI-QSAR models can be used with high reliability to classify compounds of low- and high-predicted eye irritation scores. Thus, the models offer the opportunity to reduce animal testing for compounds predicted to fall into these two extreme eye-irritation score sets. The MI-QSAR paradigm may also be applicable to other toxicological endpoints, such as skin irritation, where interactions with cellular membranes are likely.

Varied tropism of HIV-1 isolates derived from different regions of adult brain cortex discriminate between patients with and without AIDS dementia complex (ADC): evidence for neurotropic HIV variants

A number of infected individuals develop neuropathological disorders, such as AIDS dementia complex (ADC), as a consequence of HIV/AIDS. The biological features governing HIV entry and tropism in different brain cell types remain unclear, as do the genetics of the virus regulating these events and the neuropathogenic processes within the brain tissues. HIV-1 was isolated from the right and left parietal, occipital, and frontal lobes of the brain cortex of three HIV-1-infected patients: two with ADC and one without. The viral strains were studied from the innate tissues and various primary cell cultures. The kinetics and tropism of viral strains from different brain regions showed clear differences on various primary cell types (monocytes, monocyte-derived macrophages, and T cells), which could discriminate between biological behavior of HIV-1 strains from patients with and without ADC. The variable effect of different donor cells on tropism was also clearly evident. The majority (with a few exceptions) of isolates from different brain regions of all three patients used CCR5 as coreceptor for entry. The consistent CCR5 use, macrophage tropism, and non-syncytium-inducing phenotype were the main characteristics of the brain-derived HIV-1 strains from all three patients. Importantly, viral strains derived directly from innate brain tissue of the patient without ADC showed some differences from the cultured variants of the same patient, whereas those from brain tissue of the patients with ADC were more similar to the culture-adapted strains. This suggests that the emergence of primary cell type-adapted isolates during ADC may play a crucial role in the development and progression of the neuropathology associated with ADC. The different genotypes residing in different areas of brain combined with their differential tropism and coreceptor use suggest that neurotropic variants exist that may be governing the neurological manifestation of HIV disease in infected patients.

Myotropic effects of new proctolin analogues modified in the position 5 of peptide chain in insects

To explain the role of the Thr5 residue of proctolin (Arg-Tyr-Leu-Pro-Thr) in the myotropic activity of this insect neuropeptide, we synthesized two groups of its analogues: 1) Arg-Tyr-Leu-Pro-X-OH with X = Val (1), D-Val (2), Ile (3), D-Ile (4), Ala (5), D-Ala (6), Asn (7), Gln (8), Ser (9), Pro (10), Phe (11), Asp (12), Glu (13), Arg (14), D-Arg (15), Lys (16) and Gly (17) and 2) Arg-Tyr-Leu-Pro-R', where R' = isobutylamine (18), S-1-methyl-1-phenylmethylamine (19), R-1-methyl-1-phenylmethylamine (20), R-2-amino-1-propanol (21), S-2-amino-1-propanol (22), R-1-amino-2-propanol (23), S-2-amino-1-propanol (24), 3-amino-1-propanol (25). Decapeptide proctolylproctolin (H-Arg-Tyr-Leu-Pro-Thr-Arg-Tyr-Leu-Pro-Thr-OH) (26) was synthesized. Syntheses of these peptides were carried out by solid-phase method. All peptides were bioassayed in vitro on the semi-isolated hearts of Tenebrio molitor using a cardioexcitatory test and on the foregut of locust (Schistocerca gregaria). Peptides 1, 3, 5, 9, 13, 14, 16, 22, and 23 retained about 30-50% of the cardioexcitatory activity in T. molitor. Analogues 1 and 3 preserved about 50% and analogue 8 about 80% of the myotropic activity, whereas compound 4 and 9 showed a very weak contractile activity in S. gregaria.

Synthesis and biological evaluation of selected insect neuropeptide analogs modified by D- or L-phenylglycine derivatives

Novel analogs, modified by L- or D- phenylglycine and p-substituted derivatives, of the neuromodulator proctolin (Arg-Tyr-Leu-Pro-Thr) and of the Trypsin Modulating Oostatic Factor from the gray flesh fly Neobellieria bullata (Neb-TMOF-Asn-Pro-Thr-Asn-Leu-His) were synthesized and checked for activity. Proctolin analogs were modified at position 2: Arg-Phg-Leu-Pro-Thr (I), Arg-D-Phg-Leu-Pro-Thr (II), Arg-Phg(p-OH)-Leu-Pro-Thr (III), Arg-D-Phg(p-OH)-Leu-Pro-Thr (IV), Arg-Phg(p-NO2)-Leu-Pro-Thr (V) Arg-D-Phg(p-NO2)-Leu-Pro-Thr (VI), Arg-Phg(p-NH2)-Leu-Pro-Thr (VII), Arg-D-Phg(p-NH2)-Leu-Pro-Thr (VIII), Arg-Phg(p-N,N-di-Me)-Leu-Pro-Thr (IX), Arg-D-Phg(pp-N,N-di-Me)-Leu-Pro-Thr (X) while analogs of Neb-TMOF underwent modifications at position 6: Asn-Pro-Thr-Asn-Leu-Phg(p-NO2) (XI), Asn-Pro-Thr-Asn-Leu-D-Phg(p-NO2) (XII), Asn-Pro-Thr-Asn-Leu-Phg(p-NH2) (XIII), Asn-Pro-Thr-Asn-Leu-D-Phg(p-NH2) (XIV), Asn-Pro-Thr-Asn-Leu-Phg(p-N,N-di-Me) (XV), Asn-Pro-Thr-Asn-Leu-D-Phg(p-N,N-di-Me) (XVI). Earlier studies on proctolin demonstrated that the presence of the -CH2- group between C-alpha and the phenyl ring at position 2 of the peptide chain is important for the myotropic activity. Based on these results, we replaced Tyr at position 2 by different phenylglycine derivatives, lacking the methylene group at the side chain. Myotropic activity of the proctolin analogs was assayed in vitro on the semi-isolated heart of the mealworm Tenebrio molitor and on the foregut of the locust Schistocerca gregaria. All analogs (I-X) were practically inactive. For Neb-TMOF, it was previously demonstrated that the exchange of His-6 by p-substituted Phe-derivatives, especially by Phe(p-NH2), an amino acid containing a basic function, results into analogs which inhibit trypsin biosynthesis in the gray fleshfly. For this reason these new Neb-TMOF analogs with L- or D-phenylglycine p-substituted derivatives at position 6, were developed and tested (in vivo) in the trypsin biosynthesis assay of the gray fleshfly N. bullata. Only analogs XV and XVI slightly inhibited trypsin biosynthesis in the midgut. Because more than 50% of the injected animals died and none of the surviving animals ate much of the liver meal, the lower trypsin level in the gut might be a indirect effect. Other peptides (XI-XIV) had no effect on the level of trypsin biosynthesis in the midgut.

Vaccination with inactivated virus but not viral DNA reduces virus load following challenge with a heterologous and virulent isolate of feline immunodeficiency virus

It has been shown that cats can be protected against infection with the prototypic Petaluma strain of feline immunodeficiency virus (FIV(PET)) using vaccines based on either inactivated virus particles or replication-defective proviral DNA. However, the utility of such vaccines in the field is uncertain, given the absence of consistent protection against antigenically distinct strains and the concern that the Petaluma strain may be an unrepresentative, attenuated isolate. Since reduction of viral pathogenicity and dissemination may be useful outcomes of vaccination, even in the absence of complete protection, we tested whether either of these vaccine strategies ameliorates the early course of infection following challenge with heterologous and more virulent isolates. We now report that an inactivated virus vaccine, which generates high levels of virus neutralizing antibodies, confers reduced virus loads following challenge with two heterologous isolates, FIV(AM6) and FIV(GL8). This vaccine also prevented the marked early decline in CD4/CD8 ratio seen in FIV(GL8)-infected cats. In contrast, DNA vaccines based on either FIV(PET) or FIV(GL8), which induce cell-mediated responses but no detectable antiviral antibodies, protected a fraction of cats against infection with FIV(PET) but had no measurable effect on virus load when the infecting virus was FIV(GL8). These results indicate that the more virulent FIV(GL8) is intrinsically more resistant to vaccinal immunity than the FIV(PET) strain and that a broad spectrum of responses which includes virus neutralizing antibodies is a desirable goal for lentivirus vaccine development.

Functional human corneal equivalents constructed from cell lines

Human corneal equivalents comprising the three main layers of the cornea (epithelium, stroma, and endothelium) were constructed. Each cellular layer was fabricated from immortalized human corneal cells that were screened for use on the basis of morphological, biochemical, and electrophysiological similarity to their natural counterparts. The resulting corneal equivalents mimicked human corneas in key physical and physiological functions, including morphology, biochemical marker expression, transparency, ion and fluid transport, and gene expression. Morphological and functional equivalents to human corneas that can be produced in vitro have immediate applications in toxicity and drug efficacy testing, and form the basis for future development of implantable tissues.

Performance of open-fronted microbiological safety cabinets: the value of operator protection tests during routine servicing

The performance of class I and II microbiological safety cabinets over 7 years, employed in a force-ventilated containment level 3 (CL-3) laboratory, is described. Operator Protection (OP) provided by the cabinets, assessed by still and latterly limited 'in-use' KI-Discus tests, showed no overall deterioration during the review period. Comparisons show that a selected class II unit, but not a second, and a new class II MSC in a recently commissioned, similar CL-3 facility, provide the same order of OP as a class I cabinet. From the experiences described, it is strongly recommended that OP tests (OPTs) should be part of the routine servicing regime to ensure that cabinets meet required performance levels, and additionally to allow detection and rectification of poor containment, particularly where induced by environmental factors. The value of OPTs is discussed with reference to certain national standards.

Treatment of nondysgerminomatous ovarian germ cell tumors: an analysis of 69 cases

BACKGROUND

Combination chemotherapy has dramatically improved the prognosis of patients with nondysgerminomatous ovarian germ cell tumors (NDOGCT). However, guidelines are needed for the identification of patients at risk of relapse.

METHODS

The authors performed a retrospective analysis of women with NDOGCT managed during the period 1970-1994 at the Royal Marsden Hospital and other hospitals of the London Gynaecological Oncology Group.

RESULTS

Sixty-nine women were included; their median follow-up was 5.7 years (minimum, 12 months). The median age was 21 years (range, 4-44 years), with a histology of immature teratoma (IT) for 17 patients, endodermal sinus tumor (EST) for 20 patients, and mixed tumors for 32 patients. Thirty-five patients (51%) had Stage I disease. Nine patients with Stage I tumors were observed without further therapy (six with IT and three with mixed tumors), and one relapsed. Seven patients received non-platinum-based chemotherapy, and four relapsed. A total of 52 patients were treated with platinum-based chemotherapy, with relapse free and overall survival rates of 87% (95% confidence interval [CI], 73-93%) and 84% (95% CI, 70-91%), respectively. Of these patients, relapse was seen in 0 of 9 IT patients, 1 of 25 patients with mixed tumors, and 6 of 18 EST patients. With alpha-fetoprotein (AFP) > 1000 kU/L, relapse was seen in 6 of 18 patients compared with 1 of 33 relapses with lower AFP levels. In multivariate analysis, including all patients who received chemotherapy, AFP >1000 kU/L (P = 0.001) and non-platinum-based chemotherapy (P = 0.005) were associated with relapse. When only patients given platinum-based treatment were considered, EST histology (P = 0.003) and AFP >1000 kU/L (P = 0.003) were associated with relapse in univariate analysis; however, these factors were linked. No malignant tumor was found at second-look surgery performed on 24 patients. Of 26 women assessable for fertility, 24 subsequently recommenced regular menstrual function, and 11 patients had pregnancies.

CONCLUSIONS

Platinum-based chemotherapy has been confirmed to be effective in the management of patients with NDOGCT. Relapses were principally seen among patients with AFP >1000 kU/L or pure EST histology. Efforts to improve outcome need to focus on patients with EST, whereas less intensive management strategies may be appropriate for some patients with IT.

The Assessment of Quality of Life (AQoL) instrument: a psychometric measure of health-related quality of life

This paper describes constructing the Assessment of Quality of Life (AQoL) instrument; designed to measure health-related quality of life (HRQoL), and to be the descriptive system for a multi-attribute utility instrument. Unlike previous utility instruments' descriptive systems, the AQoL's has been developed using state-of-the-art psychometric procedures. The result is a descriptive system which emphasizes five different facets of HRQoL and which can claim to have construct validity. Based on the WHO's definition of health a model of HRQoL was developed. Items were written by focus groups of doctors and the researchers. These were administered to a construction sample, comprising hospital patients, and community members chosen at random. Final construction was through an iterative process of factor and reliability analyses. The AQoL measures 5 dimensions: illness, independent living, social relationships, physical senses and psychological wellbeing. Each has three items. Exploratory factor analysis showed the dimensions were orthogonal, and each was unidimensional. Internal consistency was alpha = 0.81. Structural equation modeling explored its internal structure; the comparative fit index was 0.90. These preliminary results indicate the AQoL has the prerequisite qualities for a psychometric HRQoL instrument for evaluation; replication with a larger sample is needed to verify these findings. Scaling it for economic evaluation using utilities is being undertaken. Respondents have indicated the AQoL is easy to understand and is quickly completed. Its initial properties suggest it may be widely applicable.

Comparison of in vitro and in vivo human skin responses to consumer products and ingredients with a range of irritancy potential

Human skin equivalent cultures were investigated as possible pre-clinical skin irritation screens to aid safety assessments for chemicals and product formulations, and to facilitate design of safe and efficient human studies. In vitro responses in human skin equivalent cultures were compared directly to in vivo human skin responses from historic or concurrent skin tests for representative chemicals and products, including surfactants, cosmetics, antiperspirants, and deodorants. The in vivo data consisted of visual scores (i.e., erythema and edema) from skin-patch tests and diary accounts of skin irritation from product-use studies. In the in vitro studies, cornified, air-interfaced human skin cultures (EpiDerm) were evaluated using methods designed to parallel human clinical protocols with topical dosing of neat or diluted test substances to the stratum corneum surface of the skin cultures. The in vitro endpoints have previously been shown to be relevant to human skin irritation in vivo, including the MTT metabolism assay of cell viability, enzyme release (lactate dehydrogenase and aspartate aminotransferase), and inflammatory cytokine expression (Interleukin-1alpha). For surfactants, dose-response curves of MTT cell-viability data clearly distinguished strongly-irritating from milder surfactants and rank-ordered irritancy potential in a manner similar to repeat-application (3x), patch-test results. For the antiperspirant and deodorant products, all the in vitro endpoints correlated well with consumer-reported irritation (r, 0.75-0.94), with Interleukin-1alpha (IL-1alpha) release, showing the greatest capacity to distinguish irritancy over a broad range. IL-1alpha release also showed the best prediction of human skin scores from 14-day cumulative irritancy tests of cosmetic products. These results confirm the potential value of cornified human skin cultures as in vitro pre-clinical screens for prediction of human skin irritation responses. A preliminary report of these results has been published.

Further proctolin analogues modified in the position 2 of the peptide chain and their myotropic effects in insects Tenebrio molitor and Schistocerca gregaria

We have extended our studies on the structure-activity relationship in neuropeptide proctolin (Arg-Tyr-Leu-Pro-Thr) by evaluating the effects of a series of proctolin analogues modified in position 2 of the peptide chain, including: [Phe(p-Cl)2]- (1), [D-Phe(p-Cl)2]- (2), [N-Me-Tyr2]- (3), [D-Phe(p-NH2)2]- (4), [D-Phe(p-N,N-di-Me)2]- (5), [N-Me-Tyr(OMe)]- (6), [D-3-Pal2]- (7), [L-Nal2]- (8), [D-Nal2]- (9), [Lys(Nic)2]- (10), [D-Lys(Nic)2]- (11), [D-Phe-(p-NO2)2]- (12). These peptides were evaluated for myotropic activity on the heart of Tenebrio molitor and contractile activity of the foregut of Schistocerca gregaria. Analogues 1-5, 7-9, and 12 retained a weak cardiotropic activity in Tenebrio molitor while peptides 1, 8 and 12 preserved 15-25% of the locust-gut contracting activity of proctolin. Peptides 2, 4 and 7 showed weak inhibitory activity in Schistocerca gregaria foregut, whereas only peptides 4 and 7 reduced the maximum response to applied proctolin by 64% and 49% respectively, at the 10(-6) M concentration.

Randomized trial of dose-intensity with single-agent carboplatin in patients with epithelial ovarian cancer. London Gynaecological Oncology Group

PURPOSE

We have examined the role of an increase in cisplatin dose-intensity in patients with advanced epithelial ovarian cancer by means of single-agent carboplatin therapy.

PATIENTS AND METHODS

Two hundred twenty-seven patients were randomized to treatment and eligible for analysis. The dose of carboplatin was calculated according to the Calvert formula. One hundred seventeen patients received carboplatin at an area under the concentration time curve (AUC) of 6 for six courses, administered every 28 days, and 110 patients received carboplatin at an AUC of 12 for four courses, administered every 28 days. Patients were eligible provided they had not received prior chemotherapy or radiotherapy and had International Federation of Gynecology and Obstetrics stages II to IV or relapsed stage I epithelial ovarian cancer.

RESULTS

The planned total-dose increase was 33% for the patients treated with carboplatin AUC 12, but the received percentage total-dose increase was 20%. There were no differences in progression-free or overall survival between the two treatment arms; the overall survival rate at 5 years was 31% and 34% of patients treated at AUCs 6 and 12, respectively. There was significantly more toxicity associated with carboplatin AUC 12, which resulted in more treatment delays and/or dose reductions (52% v 18%; P < .001).

CONCLUSION

We have shown that carboplatin can be delivered at an AUC of 12 for four courses without granulocyte colony-stimulating factor support, although significant hematologic toxicity occurs. Nonhematologic toxicities were not clinically significant. Carboplatin offers an opportunity to intensify cisplatin therapy, but a greater than two-fold increase in dose-intensity probably needs to be achieved before significant effects on survival will be produced and hematologic support will be required.

Volumetric object modeling for surgical simulation

Surgical simulation has many applications in medical education, surgical training, surgical planning and intra-operative assistance. However, extending current surface-based computer graphics methods to model phenomena such as the deformation, cutting, tearing or repairing of soft tissues poses significant challenges for real-time interactions. This paper discusses the use of volumetric methods for modeling complex anatomy and tissue interactions. New techniques are introduced that use volumetric methods for modeling soft-tissue deformation and tissue cutting at interactive rates. An initial prototype for simulating arthroscopic knee surgery is described which uses volumetric models of the knee derived from 3-D magnetic resonance imaging, visual feedback via real-time volume and polygon rendering, and haptic feedback provided by a force-feedback device.

New proctolin analogues and their myotropic effects on heart of yellow mealworm Tenebrio molitor L. and foregut of locust-Schistocerca gregaria L

We have extended our work on structure/activity relationship of neuropeptide proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH) by evaluating the effects of the following proctolin analogues: H-X1-Tyr-Leu-Pro-Thr-OH, where X1 = D-Arg (1), N-Me-Arg (2), Can (3), D-Tyr2, D-Leu3, D-Thr5]-proctolin (12). In analogues 1-9, the N-terminal Arg-residue was replaced by basic amino acid derivatives with peptides containing amino acid residues with an isosteric system on the back side chain relative to Arg (compounds 3, 5 and 6) or homo-Arg (compound 7). Analogues 1-12 were evaluated for myotropic action on in vitro heart preparation of Tenebrio molitor, whereas peptides 2, 5 and 7-12 were tested for contractile action on isolated foregut of Schistocerca gregaria. Peptides 2 and 3 retained full cardiotropic activity in Tenebrio molitor while peptides 5 and 7 preserved 40% and 15%, respectively, locust-gut contracting activity of proctolin. Peptides 11 and 12 showed antagonistic activity in Schistocerca gregaria foregut.

Review of autologous and allogeneic blood transfusion practices in patients undergoing radical hysterectomy

To review the practice and predictors of autologous (AUT) and allogeneic blood transfusion in patients undergoing radical hysterectomy (RH). All patients undergoing RH between April 1, 1991 and March 31, 1995 were identified by the hospital blood bank. Clinical and tumour characteristics were abstracted from the charts of endometrial cancer patients, and amalgamated with our cervical cancer RH database. Pre and post-operative hemoglobin (Hg), the number of units of AUT blood requested, obtained, and transfused, and the number of units of allogeneic blood transfused were obtained from the blood bank records. Forty eight of the 111 patients undergoing RH during the study period predeposited AUT blood. There were no differences in the median age, quetelet index, American Society of Anaesthesiologists classification of physical status, or blood loss between the AUT and non-donors. The tumour size was greater in the AUT donors, and the preoperative Hg was greater in the non donors (p = 0.001, p < 0.04 respectively). Operative time was less in the AUT donors (2.1 hrs vs 2.7 hrs, p < 0.001), and there was a significant difference in the use of the AUT program between the 3 surgeons (0.5%, 68%, p < 0.0001). Despite similar blood loss, 98% and 33% of AUT and non-donors were transfused intra/postop respectively (p < 0.0001). Regression analysis revealed surgeon (p < 0.0001) to be the only predictor of AUT donation. Blood loss was found to be the only predictor of intraoperative/postoperative blood transfusion in the non donor group (p = 0.0006). The utilization of an AUT blood program differs significantly between surgeons. Physicians are more liberal to transfuse AUT than allogeneic blood.

IRAG working group 3. Cell function-based assays. Interagency Regulatory Alternatives Group

Cell function-based tests measure responses of cells at sublytic concentrations of test agents. The fluorescein leakage assay measures effects of substances on the barrier function of epithelial monolayers or multilayers (MDCK or NHEK cells) as in vitro models of corneal epithelial function. Two IRAG data submissions suggest that the fluorescein leakage assay shows promise as a screening test for surfactants and alcohols. The test method requires further optimization, standardization and evaluation to fully determine its utility as an in vitro ocular irritancy test. The silicon microphysiometer test measures effects of test substances on the metabolic rate of cells; although a large number of cell types have been evaluated, L929 cells have been used for irritancy screening. Three IRAG data submissions on the silicon microphysiometer test showed strong in vivo/in vitro correlations for surfactants and surfactant-based personal care and household cleaning products in a range of mild to moderate ocular irritancy. This and published information support the reproducibility of the method and its use as an ocular irritancy screening test for aqueous-soluble liquid, surfactant-based formulations.