IRAG working group 5. Other assays. Interagency Regulatory Alternatives Group

As part of the Interagency Regulatory Alternatives Group (IRAG) program to evaluate the state of the art in the development of alternative (non-whole animal) eye irritation tests, academic and industrial organizations were invited to submit in vitro eye irritation data generated in their laboratories to one of several working groups for review. The assays reviewed in this report (from Working Group 5. "Other Assays") were the EYTEX assay, tissue equivalent assay, a cytotoxicity assay using three-dimensional human fibroblast constructs, the Microtox assay, and other miscellaneous assays. Each submission consisted of raw data for chemicals and products tested, a description of the methodology, and an analysis (generally by regression analysis and Pearson's correlation coefficient) for the performance of the in vitro test relative to its ability to predict individual ocular tissue scores or total ocular score. In vivo data were generated according to the scoring methods proposed by Draize. Working Group 5 evaluated the submissions and commented on the utility of the assays. The variability of the in vivo data made conclusions difficult in many situations. Most of these assays were deemed useful (within limited chemical classes) for screening purposes or for use in conjunction with other toxicological information.

Single-agent paclitaxel in patients with previously untreated stage IV epithelial ovarian cancer. London Gynaecological Oncology and North Thames Gynaecological Oncology Groups

The aim of this study was to evaluate the efficacy of high-dose paclitaxel in patients with previously untreated stage IV epithelial ovarian cancer. Paclitaxel was administered intravenously over 3 h at a dose of 225 mg m(-2) on a 21-day cycle for six courses. Thirty-six patients were entered into this study; all 36 were assessed for toxicity and 33 patients were evaluable for response. One patient had a complete response and 12 patients had partial responses (overall response rate 39.4%, 95% CI 23-58%). The overall median duration of response was 9 months (range 3.5-23+ months). The response rate to carboplatin following failure of paclitaxel within 1 year of stopping therapy was 57% (four out of seven patients). The median survival of patients was 17.2 months. The main toxicity encountered was neutropenia which was WHO grade 3 in 11 patients (31%) and WHO grade 4 in seven patients (19%). Granulocyte colony-stimulating factor (GCSF) was not given to any patient during the study. Other toxicities were: grade 3/4 infection (11%) and nausea and vomiting (11%); grade 3 bone pain (22%), fatigue (14%), diarrhoea (3%), myalgia/arthralgia (3%) and dry eyes (3%). Transient peripheral neuropathy occurred in 16 patients (44%), and alopecia was encountered in most patients (grade 2/3, 78%). Paclitaxel given at 225 mg m(-2) to patients with stage IV epithelial ovarian cancer is active, well tolerated and does not require GCSF support.

A phase II study of leuprolide in advanced/recurrent endometrial cancer

In order to determine the efficacy and toxicity of the gonadotrophin-releasing hormone agonist Leuprolide in the management of patients with recurrent or metastatic endometrial cancer, we performed a phase II study. Patients were included if there was clinical or radiological documentation of bidimensionally measurable recurrent or metastatic endometrial cancer that was deemed incurable. Treatment was 7.5 mg i.m. every 28 days, and was to continue for at least 2 courses until evidence of disease progression, patient requested withdrawal, or unacceptable toxicity. Twenty-five patients received Leuprolide for recurrent or metastatic endometrial cancer. The median age at study entry was 62 years, and the median time from initial diagnosis to first course of Leuprolide was 25 months. Six patients had received no systemic or radiotherapy prior to study entry, and 2 of these had not previously undergone hysterectomy. Fifteen patients received prior pelvic radiotherapy and 3 patients received prior whole abdominal radiotherapy. Nine of the 25 patients had received prior progestational agents, and 2 had received prior systemic chemotherapy. There were no responders, 8 patients had stable disease for a median 5 months (range 1-8), 14 patients progressed on therapy, and 3 patients were not evaluable for response due to receiving only 1 treatment. One patient experienced a grade 3 toxicity that was possibly attributable to Leuprolide (deep venous thrombosis). The median survival from study entry was 6 months. Twelve patients received progesterone after discontinuing this study, and none responded. Leuprolide does not appear to be a clinically active agent in the treatment of recurrent or metastatic endometrial cancer.

Vaccination with fixed feline immunodeficiency virus (FIV) infected cells: protection, breakthrough and specificity of response

Infection of cats with feline immunodeficiency virus (FIV), a naturally occurring lentivirus infection of cats which causes an AIDS-like disease, has generated considerable interest as an animal model for HIV vaccination. This paper reports on experiments performed to examine the potential of a fixed infected cell vaccine to confer protection against intraperitoneal challenge with cell-free FIV. The cell vaccine was highly immunogenic and elicited antibody responses to virus core antigen, p24, high virus neutralizing (VN) antibody titres, and antibodies which recognized cellular components of the vaccine. Whilst protection, assessed by the inability to detect infectious virus by virus isolation or polymerase chain reaction, against homologous but not heterologous FIV isolates was apparent up to week 12 post-challenge, when cats were monitored longer up to week 50 post-challenge a breakthrough in vaccine protection against homologous virus was observed. Protection could not be correlated with levels of antibody to p24 or VN antibody titres. In contrast with simian immunodeficiency virus vaccine studies in macaques there was no clear evidence that antibodies recognizing cellular components of the vaccine, including MHC class I and II antigens, conferred any protective effect following challenge. These results indicate that long-term post-challenge monitoring for infection is essential in lentivirus vaccine trials.

Immunogenicity of a peptide from a major neutralising determinant of the feline immunodeficiency virus surface glycoprotein

The third variable region (V3) of the feline immunodeficiency virus (FIV) surface glycoprotein is predicted to have similar physical properties to that of HIV and has been shown to contain immunodominant and neutralizing epitopes. Immunological characteristics of this region were investigated further using a peptide corresponding to the middle of the putative FIV V3 loop. The peptide was recognized in ELISA by sera from the majority of naturally FIV-infected cats, and absorbed a significant fraction of the virus neutralizing activity from a pool of sera of cats naturally infected with FIV, confirming the immunogenic nature of this region. A sheep immunized with an octameric form of the peptide (multiple antigenic peptide; MAP) in Freund's complete adjuvant generated neutralizing antibody to a higher titre than infected cats. However, immunization of cats with the same MAP in an acceptable adjuvant formulation (Quil A) induced antibody and cytotoxic T-cell responses to the immunizing peptides but only minimal neutralizing activity. These responses did not significantly alter the kinetics of infection or the proviral load after challenge with a homologous strain of FIV, compared with naive controls. While the potential efficacy of peptide vaccines to lentiviruses remains to be determined, this study shows that the immune response evoked may be highly dependent on the delivery and adjuvant regime used.

Aorto-iliac reconstruction without arteriography

BACKGROUND

Duplex imaging has been shown to be as accurate as arteriography in detecting hemodynamically significant aorto-iliac stenosis or occlusions.

METHODS

Review of the duplex scan and arteriogram reports for all primary aorto-iliac reconstructions performed during an 18-month period was undertaken. Deviations from the preoperatively planned procedure were determined. The role of the duplex scan on procedure selection was assessed.

RESULTS

Of the 54 patients identified, 13 had both duplex scan and arteriography (group I), 30 had only arteriography (group II), and 11 had only duplex scans (group III). Ten group I, 15 group II, and 9 group III patients had an occluded aorta or iliac artery. Two patients (3 anastomosis) required placement of the distal anastomosis on the common femoral rather than the external iliac artery as planned preoperatively. Both had been arteriogrammed. No group III patient required deviation from the preoperative plan.

CONCLUSION

Aorto-iliac reconstruction can be performed without arteriography when a totally occluded aorta or iliac artery is identified by duplex scanning.

Development of an in vitro method for skin corrosion testing

National and international regulations require that chemicals must be properly classified, labeled, packaged, and transported based on their ability to damage or destroy tissue, e.g., skin. Traditionally, skin corrosion assessments were based on tests involving topical application of test substances to the skin of rabbits. In the present work, an in vitro skin corrosion test based on the use of reconstructed human skin cultures was developed as a potential replacement for in vivo rabbit skin tests for corrosion. In the in vitro method, test substances were applied topically to the stratum corneum surface of human skin cultures. Skin culture damage or cytotoxicity was measured as decreased 3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyltetrazolium bromide (MTT) vital dye metabolism. In time-course experiments, the time (in minutes) of test material exposure eliciting a 50% reduction of MTT metabolism (i.e., t50 value) was calculated. Using this method we evaluated 24 chemicals and found that the 9 corrosive chemicals were accurately distinguished from 15 strong, moderate, or mild skin irritants, using an in vitro cutoff of t50 < 3 min. Histologic examination of the cultures indicated gradations of epidermal necrosis quantitated using a specially designed grading scale, which correlated well with the corrosivity of treatment chemicals and cytotoxicity measurements. The predictivity of the method was confirmed and was consistent in skin culture models from two suppliers. Thus, the utility of human skin equivalent cultures as a screening tool for prediction of skin corrosivity appears to be independent of the commercial source of the cultures. We conclude that the in vitro assay using human skin equivalent cultures is a promising alternative to in vivo rabbit skin corrosion tests for assessment of the corrosivity of chemicals to human skin.

Determination of the intra- and interlaboratory reproducibility of the low volume eye test and its statistical relationship to the Draize eye test

The reproducibility of toxicologic test methods, including alternative tests, is a key scientific and regulatory concern. In the present work, historic rabbit eye irritation data were used to determine the intra- and interlaboratory reproducibility of the low volume eye test (LVET). The standard Draize eye irritation test was used as the basis for comparison. The LVET and Draize tests had similar degrees of intra- and interlaboratory reproducibility as determined by examination of their coefficients of variation, although the variability in LVET results was directionally lower. Results from 70 parallel Draize and LVET tests indicated a strong positive association between results from the two tests, for corneal, iridial, conjunctival, and maximum average scores (MAS). Correlation coefficients were 0.60, 0.73, 0.69, and 0.73, respectively (P </= 0.0001). The linear relationship between LVET and Draize MAS values was examined by regression analysis and found to follow the relationship LVET MAS = 0.522 (Draize MAS). Thus, the LVET is at least as reproducible as the Draize test and gives responses that are (linearly) correlated to the Draize. The previous findings that the LVET is more predictive of human eye responses than the Draize test lends additional support for its use as a refined alternative to the Draize test.

Conformational and receptor-binding properties of the insect neuropeptide proctolin and its analogues

Proctolin (Arg-Tyr-Leu-Pro-Thr) was the first insect neuropeptide to be chemically characterised. It plays an essential role in insect neurophysiology and is involved in muscular contraction and neuromodulation. Elements of secondary structure in solution have been studied by comparing data obtained from NMR and molecular dynamics simulations. Different secondary structural requirements are associated with agonist and antagonist activities. A favoured conformation of proctolin has an inverse gamma-turn, comprising an intramolecular hydrogen bond near the C-terminal end between Thr NH and Leu CO. Antagonists have a more compact structure resembling a 'paperclip' loop, containing an intramolecular hydrogen bond between Tyr NH and Pro CO, possibly stabilised by a salt bridge between the N- and C-terminal groups. A cyclic analogue retains antagonist activity and resembles a beta-bulge loop, also comprising intramolecular hydrogen bonds between Tyr NH and Pro CO and Thr CO. These models may offer feasible starting points for designing novel compounds with proctolinergic activity.

Does aggressive therapy improve survival in suboptimal stage IIIc/IV ovarian cancer? A Canadian-American comparative study

In an effort to determine if differences exist in the treatment and outcome of patients with suboptimally debulked stage IIIc and IV epithelial ovarian cancer between two tertiary-care cancer centers in Canada and the United States, we conducted a comparative study. The records of all patients who underwent treatment for epithelial ovarian cancer at two tertiary-care cancer centers in Canada and the United States between 1987 and 1989 were abstracted onto a common datasheet which was then entered into a computerized database for analysis. Only patients with suboptimally debulked stage IIIc disease (residual tumor diameter > 1 cm) or stage IV were included in the comparative study. There was a total of 129 evaluable patients (61 Canadian, 68 American). There were no statistically significant differences between the centers in mean age, performance status, histology, grade, or stage distribution. During the period of this study there was no statistically significant difference between the two institutions in the proportion of patients in whom optimal debulking was achieved (Canadian 19%, American 26%). The American patients were heavier than the Canadian patients (Quetelet index 27.3 vs 23.8, P < 0.006). Primary chemotherapy included a platin-containing regimen in 98 and 93% of Canadian and American patients, respectively. The average number of laparotomies each patient received during her course of illness was 1.7 and 2.5 at the Canadian and the American centers, respectively (P < 0.0001). Similarly, the American patients received a higher mean number of different chemotherapy regimens and total number of courses of chemotherapy during the course of their disease (3.0 and 12.6) than did the Canadian patients (2.4 and 8.8) (P < 0.01 and P < 0.001, respectively). The median survival was 21 months and 20 months in the Canadian and the American patients, respectively (no significant difference), and the 5-year survival was 10% for the Canadian and 11% for the American patients. Despite significant differences in the overall aggressiveness of treatment between the two centers, there was no difference in the survival of these patients. Until effective salvage agents or treatment strategies are realized, "more is not necessarily better."

Development and intralaboratory evaluation of an in vitro human cell-based test to aid ocular irritancy assessments

A human cell-based in vitro method was developed to screen for ocular irritancy potential of aqueous compatible and incompatible test agents, such as liquids, insoluble solids, powders, granulars, emulsions, and acids/alkalis. Methods were developed for topical application (an exposure that mimics in vivo testing) and wash-off of test substances on the epithelial surface of human skin derived epithelial-fibroblast cocultures (Skin2 Model ZK1200 from Advanced Tissue Sciences). These cultures contain noncornified stratified squamous epithelium, providing a three-dimensional in vitro model that resembles noncornified mucosal epithelium, such as cornea and conjunctiva. The hypothesis tested and confirmed in this work was that the rate of cytotoxicity induced by topical application of test substances to the stratified epithelial cell cultures would correlate with ocular irritancy. Test substances were applied to the cell system for up to 30 min, and cytotoxicity was measured as decreased 3-[4,5-dimethylthiazol-2-yl]2,5-diphenyltetrazolium bromide (MTT) vital dye metabolism. The time (in minutes) of exposure to test agent that reduced MTT metabolism to 50% of control levels (the t50 value) was calculated for each test substance, and these values showed a good correlation (r = 0.87) with historic rabbit low-volume eye test maximum average scores (MAS) for a range of liquid, solid, granular, powder, and other test materials, including consumer product formulations and ingredient chemicals. Additionally, t50 values confirmed the mild nature of selected cosmetic formulations. Taken together, these data indicate that this in vitro test, termed the tissue equivalent assay, is a valuable tool to screen for irritancy of test substances to mucosal tissues, such as cornea and conjunctiva.

Hormone-dependent expression of the ovine beta-lactoglobulin gene

The minimal hormonal requirements for inducing the ovine beta-lactoglobulin gene have been investigated using mammary gland explants from ewes in the first half of pregnancy. Quantification of beta-lactoglobulin mRNA showed that a combination of insulin, cortisol and prolactin was required to stimulate the expression of the gene and that this response could not be enhanced by the addition of oestrogen and thyroid hormone to the culture medium. Explants cultured in the presence of insulin, cortisol and prolactin also demonstrated the capacity to synthesize the protein. Progesterone did not inhibit the induction of the gene, which is consistent with the increase in beta-lactoglobulin mRNA observed in vivo in the mammary gland during the final 2 months of pregnancy when the circulating level of progesterone is elevated.

Protection against homologous but not heterologous challenge induced by inactivated feline immunodeficiency virus vaccines

Whole inactivated virus vaccines from the FL4 cell line protected against challenge with homologous feline immunodeficiency virus (Petaluma strain) but not against a heterologous FIV isolate (GL-8) which is distinct from the Petaluma strain in virus neutralization. Protection was associated with a type-specific neutralizing antibody response and was retained when the challenge virus was propagated in an unrelated cell line.

Near-infrared continuum generation with upconversion into the visible in SiO(2) single-mode fiber

The conditions leading to the recent observation of efficient upconversion of 1319-nm radiation to 580 nm in SiO(2) single-mode fiber are examined. Simulation results, based on the third-order nonlinearity and the waveguiding characteristics of typical fiber, show that the visible signal may be generated by phase-matched four-wave mixing within the concurrently generated infrared spectral continuum.

Virus neutralization reveals antigenic variation among feline immunodeficiency virus isolates

By using a focus reduction assay in CrFK feline fibroblast cells, virus neutralizing antibodies (VNA) to feline immunodeficiency virus (FIV) were demonstrated in cats that had been naturally or experimentally infected with FIV. The antigenic relatedness of four strains of FIV, divergent in nucleotide sequence within the env gene, was investigated by neutralization following adaptation of each virus for growth in CrFK cells. Two of the viruses were from The Netherlands (FIV/AM-4 and AM-6), one was from the U.K. (FIV/GL-8) and one was from the U.S.A. (FIV/PET). Reaction of the viruses in the neutralization assay with cat antibodies to homologous or heterologous strains indicated that while there was a degree of cross-reactivity between all four, there were consistent differences suggesting the existence of FIV neutralization subtypes. In particular, FIV/PET and FIV/AM-6 were closely related but FIV/PET and FIV/GL-8 were clearly distinct. VNA from naturally infected cats in the field showed a pattern of reactivity against FIV/PET and FIV/GL-8 that confirmed the antigenic diversity of FIV.

High-dose methotrexate for gestational trophoblastic disease

Eighty patients with low-risk and 5 patients with intermediate-risk gestational trophoblastic neoplasia (GTN) (WHO classification) were treated with single-agent high-dose methotrexate with folinic acid rescue (MTX/FAR). By the NCI classification, 65 patients had nonmetastatic GTN, 13 patients had low-risk metastatic GTN, and 7 patients had high-risk metastatic GTN. Seventy-one (84%) patients achieved remission (beta HCG < or = 5 IU/liter) with MTX/FAR, whereas 14 (16%) failed to achieve remission with MTX/FAR alone. All failures were salvaged with second-line therapies. Patients successfully treated with MTX/FAR required a median of 4 courses to achieve remission, and a median of 2 consolidative courses. Factors found predictive of failure with MTX/FAR were pretreatment beta HCG (P = 0.003), prior history of GTN (P < 0.04), and time from termination of antecedent pregnancy to initiation of treatment (P < 0.05). No significant difference was noted between the "success" and "failure" groups with respect to MTX dose or infusion time, the timing and dosage of folinic acid rescue, the number of courses of MTX, or the mean interval between courses. Multivariate analysis revealed that the pretreatment beta HCG (P < 0.01) and short time from termination of antecedent pregnancy to initiation of treatment (P < 0.03) were independently significant for failure. No significant (grade 3/4) hematologic or gastrointestinal toxicity occurred, and no treatment delays or dose reductions were required. This regimen is both effective and well tolerated; however, the theoretical advantages of high-dose methotrexate do not appear to offer any clinical advantage over conventional dose MTX in low- and intermediate-risk GTN.

The magical and medicinal usage of Stangeria eriopus in South Africa

The underground caudex of the cycad Stangeria eriopus is used extensively by several ethnic groups in South Africa, mainly as an ingredient in magical potions but also as an emetic. An assessment of two main outlets showed that 3410 plants were sold in the month of July 1992; continued usage of this material now threatens the remaining plant populations. A proximate analysis of the caudex material gives high carbohydrate content with only small percentages of fat, protein, fibre and ash. An unusually high content of sodium sulphate may explain the efficacy of Stangeria-containing preparations as an emetic. The phytosterols sitosterol and stigmasterol are present in a 4:1 ratio while the fatty acid component comprises palmitic, oleic, stearic and arachidic acids. Twelve amino acids were identified in the material, including the non-protein amino acids beta-alanine, gamma-aminobutyric acid and pyroglutamic acid. The candidate neurotoxin beta-N-methylamino-L-alanine could not be detected but cycasin is present at the levels of 0.17% and 0.21% in fresh and dry caudex material, respectively and appears to be accompanied by the related toxin, macrozamin.

Relationship of difficult forceps delivery to dental arches and occlusion

This study examined the relationship between the extensive use of forceps procedures during delivery and later occlusal characteristics. The work uses data collected in National Collaborative Perinatal Research Project (USA), in which more than 60,000 pregnancies and the children's health were followed by regular medical tests and examinations. Of these, a subsample of 2,074 children participated in dental examinations, including the production of dental casts with wax bites to register occlusion. A total of 84 children, 55 boys and 29 girls, were coded as having undergone difficult or very difficult forceps deliveries. A control group was matched by age, sex, race, and site of dental examination. The results show a significant increase in asymmetric molar occlusion (P < 0.005) and canine relations (P < 0.001) in the study group. The sagittal length of the mandibular arch was increased in the difficult forceps delivery group (P < 0.01). In conclusion, difficult forceps procedures are associated with a later asymmetric occlusion.

An approach for development of alternative test methods based on mechanisms of skin irritation

Recent advances in techniques for culture of human skin cells have led to their potential for use as in vitro models for skin irritation testing to augment or replace existing rabbit skin patch tests. Our work is directed towards the development of cultured human skin cells, together with endpoints that can be linked to in vivo mechanisms of skin irritation, as in vitro models for prediction of human skin irritation, and for study of mechanisms of contact irritant dermatitis. Three types of commercial human skin cell cultures have been evaluated, epidermal keratinocytes and partially or fully cornified keratinocyte-dermal fibroblast co-cultures. Human epidermal keratinocyte cultures (Clonetics) were treated with product ingredients and formulations, and the extent of cell damage was assessed by incorporation of the vital dye neutral red. Cell damage correlated with human skin patch data for ingredient chemicals with the exception of acids and alkalis, but did not correlate with skin irritation to surfactant-containing product formulations. Cultures of human skin equivalents were evaluated as potential models for measurement of responses to test materials that could not be measured in the keratinocyte/neutral red assay. We developed a battery of in vitro endpoints to measure responses to prototype ingredients and formulations in human epidermal keratinocyte-dermal fibroblast co-cultures grown on a nylon mesh ('Skin2' from Advanced Tissue Sciences) or on a collagen gel ('Testskin' from Organogenesis). The endpoints measure cytotoxicity (neutral red and MTT vital dye staining, lactate dehydrogenase and N-acetyl glucosaminidase release, glucose utilization) and inflammatory mediator (prostaglandin E2) release. Initial experiments indicate a promising correlation between responses of the Skin2 model to prototype surfactants and in vivo human skin irritation. The responses of Testskin cultures to acids and alkalis help to prove the concept that a topical application model can measure responses to these materials. These results suggest that human skin cell models can provide useful systems for preclinical skin irritation assessments, as alternatives to rabbits, for at least certain classes of test substances.

Assessment of chemical disinfectants against human immunodeficiency virus: overcoming the problem of cytotoxicity and the evaluation of selected actives

The aim of this study was to develop a standardised technique for assessing the virucidal activity of commercial disinfectants against human immunodeficiency virus (HIV). In the absence of any model procedure for HIV a protocol based on German DVV guidelines was developed. A major difficulty associated with such studies is the cytotoxic effect of the biocide on the target cells used in infectivity assays. This problem is most commonly overcome by dilution of the virus-disinfectant mixture, however, this requires high titre (> or = 10(7) TCID50) virus which is difficult to achieve with HIV. We employed a simple washing technique which effectively removed cytotoxicity while retaining infectivity. Incorporated into a standard suspension test, this method supported by virus isolation procedures was sensitive and reproducible. The reliability of the procedure was confirmed by evaluating the efficacy of some commercially available cidals which were known to be cytotoxic; namely two instrument disinfectants, Sactimed-I-Steril, an aldehyde based product, Sactimed-I-Sinald a guanide/quaternary-ammonium combination, and Levermed, an alcohol based hand disinfectant.