Margetuximab with retifanlimab as first-line therapy in HER2+/PD-L1+ unresectable or metastatic gastroesophageal adenocarcinoma: MAHOGANY cohort A.

BACKGROUND: Human epidermal growth factor receptor 2 (HER2)-positive metastatic gastric and gastroesophageal adenocarcinoma (GEA) is globally treated with chemotherapy plus trastuzumab. Novel therapeutic strategies strive to not only optimize efficacy, but also limit toxicities. In MAHOGANY cohort A, margetuximab, an Fc-engineered, anti-HER2 monoclonal antibody (mAb) was combined with retifanlimab, an anti-programmed cell death protein 1 mAb, in the first-line HER2-positive/programmed death-ligand 1 (PD-L1)-positive GEA. PATIENTS AND METHODS: MAHOGANY cohort A part 1 is a single-arm trial to evaluate margetuximab plus retifanlimab in patients with HER2 immunohistochemistry 3+, PD-L1-positive (combined positive score ≥1%), and non-microsatellite instability-high tumors. Primary objectives for cohort A were safety/tolerability and the confirmed objective response rate (ORR). RESULTS: As of 3 August 2021, 43 patients were enrolled and received margetuximab/retifanlimab. Nine grade 3 treatment-related adverse events (TRAEs) were reported in eight (18.6%) patients and eight serious TRAEs in seven (16.3%) patients. There were no grade 4/5 TRAEs. Three patients discontinued margetuximab/retifanlimab because of immune-related adverse events. The ORR by independent assessment was 53% [21/40 (95% confidence interval (CI) 36.1-68.5)], with a median duration of response of 10.3 months (95% CI 4.6-not evaluable); disease control rate was 73% [29/40 (95% CI 56.1-85.4)]. The study sponsor discontinued the study in advance of the planned enrollment when it became apparent that the study design would no longer meet the requirements for drug approval because of recent advances in the treatment of GEA. CONCLUSIONS: The chemotherapy-free regimen of combined margetuximab/retifanlimab as first-line treatment in double biomarker-selected patients demonstrated a favorable toxicity profile compared with historical outcomes using chemotherapy plus trastuzumab. The ORR observed in this study compares favorably versus ORR observed with other chemotherapy-free approaches.

Safety and efficacy of HER2 blockade by trastuzumab-based chemotherapy-containing combination strategies in HER2+ gastroesophageal adenocarcinoma.

Since completion of the Trastuzumab for Gastric Cancer study, trastuzumab with doublet chemotherapy (a fluoropyrimidine and a platinum) has been the gold-standard first-line therapy for patients with locally advanced unresectable or metastatic human epidermal growth factor receptor 2-positive (HER2+) gastroesophageal adenocarcinoma (GEA). The safety and efficacy of 23 studies of first-line trastuzumab plus doublet chemotherapy, without checkpoint inhibitors (n = 19) or with checkpoint inhibitors (n = 4), conducted in patients with locally advanced unresectable or metastatic HER2+ GEA, including phase II/III, prospective, and retrospective observational studies, were summarized. In studies without checkpoint inhibitors, the median duration of trastuzumab treatment ranged from 19.5 to 39.0 weeks and from 15.3 to 30.0 weeks for chemotherapy. In studies with checkpoint inhibitors, the median duration of pembrolizumab/trastuzumab/chemotherapy was 30 weeks, and 18 weeks for chemotherapy. In studies without checkpoint inhibitors, treatment-emergent adverse events (TEAEs) of grade ≥3 ranged from 32% to 84%. Serious adverse events (SAEs) ranged from 15% to 39%. Adverse events resulting in discontinuation ranged from 0% to 30%. Treatment-related deaths occurred in 0%-9% of patients. In studies with checkpoint inhibitors, TEAEs of grade ≥3 were 57%. SAEs ranged from 31% to 38%. Adverse events resulting in discontinuation ranged from 5% to 24%. Treatment-related deaths occurred in 0%-3% of patients. In studies without checkpoint inhibitors, objective response rate (ORR) ranged from 39% to 82%, median progression-free survival (PFS) from 5.7 to 11.6 months, and median overall survival (OS) from 11.2 to 27.6 months. In studies with checkpoint inhibitors, ORR ranged from 39% to 86%, median PFS from 8.0 to 13.0 months, and median OS from 19.3 to 27.3 months. This review provides a historical benchmark on safety and efficacy of available first-line chemotherapy-based standard of care for patients with locally advanced unresectable or metastatic HER2+ GEA.

Meta-analysis of individual patient safety data from six randomized, placebo-controlled trials with the antiangiogenic VEGFR2-binding monoclonal antibody ramucirumab.

BACKGROUND: Ramucirumab, the human immunoglobulin G1 monoclonal antibody receptor antagonist of vascular endothelial growth factor receptor 2, has been approved for treating gastric/gastroesophageal junction, non-small-cell lung, and metastatic colorectal cancers. With the completion of six global, randomized, double-blind, placebo-controlled, phase III trials across multiple tumor types, an opportunity now exists to further establish the safety parameters of ramucirumab across a large patient population. MATERIALS AND METHODS: An individual patient meta-analysis across the six completed phase III trials was conducted and the relative risk (RR) and associated 95% confidence intervals (CIs) were derived using fixed-effects or mixed-effects models for all-grade and high-grade adverse events (AEs) possibly related to vascular endothelial growth factor pathway inhibition. The number needed to harm was also calculable due to the placebo-controlled nature of all six registration standard trials. RESULTS: A total of 4996 treated patients (N = 2748 in the ramucirumab arm and N = 2248 in the control, placebo arm) were included in this meta-analysis. Arterial thromboembolic events [ATE; all-grade, RR: 0.8, 95% CI 0.5-1.3; high-grade (grade ≥3), RR: 0.9, 95% CI 0.5-1.7], venous thromboembolic events (VTE; all-grade, RR: 0.7, 95% CI 0.5-1.1; high-grade, RR: 0.7, 95% CI 0.4-1.2), high-grade bleeding (RR: 1.1, 95% CI 0.8-1.5), and high-grade gastrointestinal (GI) bleeding (RR: 1.1, 95% CI 0.7-1.7) did not demonstrate a definite increased risk with ramucirumab. A higher percentage of hypertension, proteinuria, low-grade (grade 1-2) bleeding, GI perforation, infusion-related reaction, and wound-healing complications were observed in the ramucirumab arm compared with the control arm. CONCLUSIONS: Ramucirumab may be distinct among antiangiogenic agents in terms of ATE, VTE, high-grade bleeding, or high-grade GI bleeding by showing no clear evidence for an increased risk of these AEs in this meta-analysis of a large and diverse patient population. Ramucirumab is consistent with other angiogenic inhibitors in the risk of developing certain AEs. Clinical Trial Numbers: NCT00917384 (REGARD), NCT01170663 (RAINBOW), NCT01168973 (REVEL), NCT01183780 (RAISE), NCT01140347 (REACH), and NCT00703326 (ROSE).

Ramucirumab combined with FOLFOX as front-line therapy for advanced esophageal, gastroesophageal junction, or gastric adenocarcinoma: a randomized, double-blind, multicenter Phase II trial.

BACKGROUND: We report the first randomized, Phase II trial of ramucirumab, an anti-vascular endothelial growth factor receptor-2 monoclonal antibody, as front-line therapy in patients with advanced adenocarcinoma of the esophagus or gastric/gastroesophageal junction (GEJ). PATIENTS AND METHODS: Patients from the USA with advanced esophageal, gastric, or GEJ adenocarcinoma randomly received (1:1) mFOLFOX6 plus ramucirumab (8 mg/kg) or mFOLFOX6 plus placebo every 2 weeks. The primary end point was progression-free survival (PFS) with 80% power to detect a hazard ratio (HR) of 0.71 (one-sided α = 0.15). Secondary end points included evaluation of response and overall survival (OS); an exploratory ramucirumab exposure-response analysis was undertaken. RESULTS: Of 168 randomized patients, 52% of tumors were located in the stomach/GEJ and 48% in the esophagus. The trial did not meet the primary end point of PFS [6.4 versus 6.7 months, HR 0.98 (95% confidence interval 0.69-1.37)] or the secondary end point of OS (11.7 versus 11.5 months) in the intent-to-treat (ITT) population. Objective response rates (45.2% versus 46.4%) were similar between arms. Most Grade ≥3 toxicities did not differ significantly between arms, yet premature discontinuation of FOLFOX and ramucirumab (for reasons other than progressive disease) was more common among ramucirumab- versus placebo-treated patients. In an exploratory analysis that censored for premature discontinuation, the HR for PFS favored the ramucirumab arm (HR 0.76), particularly in patients with gastric/GEJ cancer. An exploratory exposure-response analysis indicated that patients with higher ramucirumab exposure had longer OS. CONCLUSION: The addition of ramucirumab to front-line mFOLFOX6 did not improve PFS in the ITT population. CLINICALTRIALSGOV IDENTIFIER: NCT01246960.

Gene expression profiling identifies responsive patients with cancer of unknown primary treated with carboplatin, paclitaxel, and everolimus: NCCTG N0871 (alliance).

BACKGROUND: Carboplatin (C) and paclitaxel (P) are standard treatments for carcinoma of unknown primary (CUP). Everolimus, an mTOR inhibitor, exhibits activity in diverse cancer types. We did a phase II trial combining everolimus with CP for CUP. We also evaluated whether a gene expression profiling (GEP) test that predicts tissue of origin (TOO) could identify responsive patients. PATIENTS AND METHODS: A tumor biopsy was required for central confirmation of CUP and GEP. Patients with metastatic, untreated CUP received everolimus (30 mg weekly) with P (200 mg/m(2)) and C (area under the curve 6) every 3 weeks. The primary end point was response rate (RR), with 22% needed for success. The GEP test categorized patients into two groups: those having a TOO where CP is versus is not considered standard therapy. RESULTS: Of 45 assessable patients, the RR was 36% (95% confidence interval 22% to 51%), which met criteria for success. Grade ≥3 toxicities were predominantly hematologic (80%). Adequate tissue for GEP was available in 38 patients and predicted 10 different TOOs. Patients with a TOO where platinum/taxane is a standard (n = 19) tended to have higher RR (53% versus 26%) and significantly longer PFS (6.4 versus 3.5 months) and OS (17.8 versus 8.3 months, P = 0.005), compared with patients (n = 19) with a TOO where platinum/taxane is not standard. CONCLUSIONS: Everolimus combined with CP demonstrated promising antitumor activity and an acceptable side-effect profile. A tumor biomarker identifying TOO may be useful to select CUP patients for specific antitumor regimens. CLINICALTRIALSGOV: NCT00936702.

Suppression of T-cell proliferation by and B7-H1 expression on human liver-derived stem cells.

BACKGROUND: Many types of stem cells have been widely used for the treatment of liver diseases. The therapeutic effect of stem cells is predominantly based on the immune regulatory properties of these cells. METHODS: We isolated human liver stem cells (HLSCs), which are considered intrahepatic stem cells, and examined their suppression of T-cell proliferation induced by phytohemagglutinin. RESULTS: HLSCs inhibited phytohemagglutinin-induced T-cell proliferation not only in direct co-culture but also in indirect co-culture in a cell number-dependent manner. That is, T-cell proliferation was substantially inhibited by cell-to-cell contact regardless of soluble factor(s). B7-H1, a co-inhibitory molecule that relies on cell-to-cell contact, was found to be constitutively expressed at low levels on HLSCs. Furthermore, its expression was upregulated moderately by tumor necrosis factor-α and dramatically by interferon-γ. CONCLUSIONS: These results suggest that HLSCs would have therapeutic effects through T-cell suppression in acute liver diseases.

In vitro differentiation of human liver-derived stem cells with mesenchymal characteristics into immature hepatocyte-like cells.

Liver transplantation is severely limited by donor shortage although it is the only effective treatment for end-stage liver disease. So the best alternative is hepatocyte transplantation. For obtaining human hepatocytes, some stem cells originating from extrahepatic or intraheptic tissues have been isolated and characterized. Previously we have reported that human liver-derived stem cells (HLSCs) could be isolated and expanded from donated livers unsuitable for transplantation; they expressed some markers of mesenchymal stem cells but neither hematopoietic nor oval cells. In this study, we isolated and expanded HLSCs with mesenchymal characteristics from another adult human liver. They showed mesenchymal morphology and grew well under serum condition similar to our previous reports. Also, they expressed some markers of mesenchymal stem cells, such as CD44, CD73, CD90, and CD105, through fluorescence-activated cell sorting analysis. When HLSCs were sequentially exposed to fibroblast growth factor-1 (FGF-1), FGF-4, and hepatocyte growth factor (HGF) followed by FGF-4, HGF, oncostatin M, and dexamethasone, they became round or polygonal, and expressed some hepatic markers such as albumin and α1-antitrypsin in the gene or protein level. Also, they showed urea synthesis activity 7 days after treatment of FGF-4, HGF, oncostatin M, and dexamethasone. These results provided that HLSCs would be a useful cell source in the field of regenerative medicine as well as liver cell biology.

B7-H1 inhibits T cell proliferation through MHC class II in human mesenchymal stem cells.

B7-H1 on mesenchymal stem cells (MSCs) is known to modulate immune response. However, its expression pattern and exact immunomodulatory mechanism are unclear. In this study, we examined the immunomodulatory mechanism through the expression pattern of B7-H1 and major histocompatibility complex class II in various MSCs. Human bone marrow, adipose tissue, and cord blood MSCs were isolated and cultured. B7-H1, HLA-ABC, and HLA-DR expression on MSCs by interferon-γ (IFN-γ) was detected time-dependently by flow cytometry. The inhibitory effect of MSCs on T lymphocytes was observed in phytohemagglutinin antigen-induced T cell proliferation assay. The expression of B7-H1 was rapidly induced, but the expression of HLA-DR was induced at 48 hours after IFN-γ treatment. The inhibitory effect of MSCs on T cell proliferation could be restored when the anti-B7-H1 monoclonal antibody was used to block the B7-H1, or when the HLA-DRα small interfering RNA was used to interfere with its expression. These results show that MSCs could inhibit the T cell proliferation and activation by B7-H1 depending on the presence of HLA-DR. Therefore, MSCs would have a strong effect on immune diseases such as graft-versus-host disease and autoimmune diseases when MSCs are primed with IFN-γ 48 hours before transplantation.

In vitro evaluation of migratory capacity of human liver stem cells influenced by soluble factors.

Although several studies have addressed the engraftment of stem cells into the liver, the exact mechanisms in vivo remain unclear. In this study, we investigated the effects of soluble factors on cell migration using purified, expanded human liver stem cells (HLSCs) obtained from a pediatric liver resection. Using a in vitro transwell migration assay, we evaluated the migratory capacity of HLSCs under the influence of the cytokines tumor necross factor- [TNF]-α, interleukin [IL]-6, and interferon (IFN)-γ or the growth factors vascular endothelial growth factor [VEGF], basic fibroblast growth factor [bFGF], and hepatocyte growth factor [HGF], which are known to be highly secreted during liver injury. We also evaluated the migratory capacity indirectly influenced by cryopreserved human hepatocytes. The migration across the transwell membrane was promoted by VEGF, bFGF, TNF-α, IFN-γ, or hepatocytes. The cryopreserved human hepatocytes especially induced significant migration. These results suggested the presence of unidentified soluble factors from hepatocytes. This experiment described a reliable system for quantitative migration studies to broaden our understanding of the directional nature of cell migration.

Fabrication and characterization of solid oxide fuel cell electrolyte films by electron beam vapor deposition.

Thin films of SDC for SOFC electrolyte were prepared using electron beam deposition technique. The influence of annealing temperature, substrate temperature and e-beam gun power on the structure and surface morphology of the thin films was examined. It was found that the SDC thin films annealed at 800 degrees C consisted of a single cubic phase and the main crystal structure of the thin films represented those of evaporated electrolyte powders. The crystal orientation of the SDC films increased with substrate temperature and decreased with e-beam gun power. The higher XRD peak intensity was observed for the SDC films deposited on NiO-YSZ substrate compared with those on SiO2 substrate due to the polycrystalline structure of the NiO-YSZ substrate. A good adhesion to the substrate and a columnar structure were observed by the fractured cross-sectional view of the SDC films on NiO-YSZ anode substrate. Electrical conductivity of SDC film with 5 microm thickness was observed to be 2.31 x 10(-3) Sm(-1) at 800 degrees C.

Synthesis of yttria-doped bismuth oxide powder by carbonate coprecipitation for IT-SOFC electrolyte.

Yttria-doped bismuth oxide (YBO) powders were synthesized by ammonium carbonate coprecipitation for the preparation of electrolytes of an intermediate temperature solid oxide fuel cell (IT-SOFC). The starting salts were yttrium and bismuth nitrate. The crystal structures and the morphological characteristics of the particles were analyzed by XRD and SEM, respectively. The ionic conductivity of the sintered pellet was measured by an electrochemical impedance analyzer. The size of the calcined YBO powders were in the range of 20-100 nm as measured by SEM images. The YBO pellets had a face-centered cubic structure, and their crystallite size was about 54-88 nm. The ionic conductivity of the YBO pellets sintered at 800 degrees C was observed to be 2.7 x 10(-1) Scm-(-1) at 700 degrees C. The ball-milling of the YBO powder before it was pelletized was found to have been unrequired probably because of a good sinterability of the YBO powders that was prepared via the ammonium carbonate coprecipitation method. The results showed that the ammonium carbonate coprecipitation process could be used as the cost-efficient method of producing YBO electrolytes for IT-SOFC.

Genetic variation in radiation and platinum pathways predicts severe acute radiation toxicity in patients with esophageal adenocarcinoma treated with cisplatin-based preoperative radiochemotherapy: results from the Eastern Cooperative Oncology Group.

PURPOSE: Germline genetic variations may partly explain the clinical observation that normal tissue tolerance to radiochemotherapy varies by individual. Our objective was to evaluate the association between single-nucleotide polymorphisms (SNPs) in radiation/platinum pathways and serious treatment-related toxicity in subjects with esophageal adenocarcinoma who received cisplatin-based preoperative radiochemotherapy. METHODS: In a multicenter clinical trial (E1201), 81 eligible treatment-naïve subjects with resectable esophageal adenocarcinoma received cisplatin-based chemotherapy concurrent with radiotherapy, with planned subsequent surgical resection. Toxicity endpoints were defined as grade ≥3 radiation-related or myelosuppressive events probably or definitely related to therapy, occurring during or up to 6 weeks following the completion of radiochemotherapy. SNPs were analyzed in 60 subjects in pathways related to nucleotide/base excision- or double stranded break repair, or platinum influx, efflux, or detoxification. RESULTS: Grade ≥3 radiation-related toxicity (mostly dysphagia) and myelosuppression occurred in 18 and 33% of subjects, respectively. The variant alleles of the XRCC2 5' flanking SNP (detected in 28% of subjects) and of GST-Pi Ile-105-Val (detected in 65% of subjects) were each associated with higher odds of serious radiation-related toxicity compared to the major allele homozygote (47% vs. 9%, and 31% vs. 0%, respectively; P = 0.005). No SNP was associated with myelosuppression. CONCLUSIONS: This novel finding in a well-characterized cohort with robust endpoint data supports further investigation of XRCC2 and GST-Pi as potential predictors of radiation toxicity.

Multipotent progenitor cells derived from human umbilical cord blood can differentiate into hepatocyte-like cells in a liver injury rat model.

Umbilical cord blood (UCB), a rich source of hematopoietic stem cells, offers practical and ethical advantages. It has been reported that various adult stem cells transplanted into a damaged liver show characteristics of a hepatic lineage. In a previous study, we reported on novel UCB-derived adult stem cells, termed umbilical cord blood-derived multipotent progenitor cells (UCB-MPCs). We demonstrated that these cells were capable of differentiating into hepatocyte- like cells in vitro. To assess the hepatic differentiation capacity of UCB-MPCs, rat models of hepatic injury were generated using carbon tetra-chloride (CCl(4)) with transplantation of cells into the liver. The transplanted cells successfully incorporated into the liver of the recipient animal differentiated into functional hepatocyte-like cells that expressed hepatocyte-specific markers, such as CK-18 and albumin. Moreover, human albumin was detected in the serum of the recipient rat model. These data indicated that UCB-MPCs were capable of displaying similar characteristics to those of functional hepatocytes in a recipient liver. UCB-MPCs may prove to be a useful, transplantable alternative for hepatic progenitor cells in both experimental and therapeutic applications.

Correlation between scaffold in vivo biocompatibility and in vitro cell compatibility using mesenchymal and mononuclear cell cultures.

The aim of this study was to compare the cell compatibility of silk and polyglycolic acid (PGA) scaffolds cultured in vitro with mesenchymal stem cells (MSCs) and peripheral blood mononuclear cells (PBMCs) to their biocompatibility in vivo following implantation. Scaffolds were knitted with silk or PGA thread and the average efficiency of cell attachment was 35 +/- 4% and 17 +/- 2% in the PGA and silk scaffold groups. Thus, the initial attachment of the MSC cells to the PGA scaffold was superior to the initial attachment of the cells on the silk scaffold. After 21 days in culture, the average cell density on the silk scaffold was 5.8 +/- 0.5 x 10(5) cells, and the average cell density of the PGA scaffolds was 6.34 +/- 0.5 x 10(5) cells. In addition, there was no cell cytoxicity observed with either scaffold. However, the immune response of in vitro cultured PBMCs was significantly higher with the PGA scaffold than with the silk scaffold. The proliferation of the PBMCs cultured on the PGA scaffold was two times greater than that of those cultured on the silk scaffold after 3 days of culture. In addition, the secretion of IL-1 by the PBMCs cultured on the PGA scaffold was superior to that of the PBMCs cultured on the silk scaffold. The secretion of IL-1beta and IFN-gamma was increased by about 50% when the PBMCs were cultured with the PGA scaffold. Silk and PGA scaffolds were also implanted subcutaneous in rats. Histological evaluation of the scaffold explants revealed the presence of monocytes and macrophages in PGA scaffold. The inflammatory tissue reaction was more conspicuous on the PGA scaffold than on the silk scaffold. These results suggest that the results of in vitro PBMC cultures were more closely related to the in vivo results of implantation than the results of in vitro MSC cultures.

Long-term seizure outcome in patients initially seizure-free after resective epilepsy surgery.

OBJECTIVE: To evaluate the likelihood of and risk factors for seizure recurrence in patients initially seizure-free after resective surgery for intractable epilepsy. METHODS: One hundred seventy-five patients who underwent lobectomy between 1972 and 1992 and were seizure-free during the first postoperative year were retrospectively studied. Outcome was measured by relapse risk, presence of auras in otherwise seizure-free patients, and seizure frequency among relapsers. Factors significant in bivariate or Kaplan-Meier analysis or considered potentially predictive a priori were included in multivariate models. RESULTS: Of the 175 patients (mean follow-up 8.4 years), 63% never relapsed. The likelihood of being seizure-free was 83 +/- 6% 3 years after surgery, 72 +/- 7% after 5 years, and 56 +/- 9% after 10 years. After adjusting for age at surgery, duration of preoperative epilepsy, and resection site, normal pathology was associated with increased risk of relapse compared to mesial temporal sclerosis or other pathology (p = 0.036; hazard ratio [HR] 2.38; 95% CI 1.06 to 5.34). Among patients otherwise seizure-free, preoperative illness of > or =20 years was associated with increased risk of postoperative auras (p = 0.040; HR 3.55; 95% CI 1.06 to 11.90). Among relapsers, 51% experienced one or fewer seizures per year. Normal pathology and earlier relapse were associated with higher postoperative seizure frequency. CONCLUSIONS: In patients seizure-free during the first year after resective epilepsy surgery, the likelihood of remaining seizure-free declined to 56% over 10 years, but half of patients who relapsed had at most one seizure per year. Longer preoperative illness and normal pathology predicted poorer outcome.

Assessment of toxic potential of industrial chemicals using a cultured human bioartificial skin model: production of interleukin 1alpha and hydroxyeicosatetraenoic acids.

Cytotoxicity assays using artificial skin are proposed as alternative methods for in vitro tests to minimize animals used in ocular and dermal irritation testing. The responses of the artificial skins were studied to a well-characterized chemical irritant, such as toluene, glutaraldehyde and sodium lauryl sulfate (SLS), and a nonirritant, such as polyethylene glycol. The evaluation of irritating and nonirritating test chemicals was also compared with responses seen in human dermal fibroblasts and human epidermal keratinocytes grown in monolayer culture. The responses monitored included the MTT mitochondrial functionality assay. In order to better understand the local mechanisms involved in skin damage and repair, the productions of several mitogenic proinflammatory mediators such as interleukin-1alpha (IL-1alpha), 12-hydroxyeicosatetraenoic acid (12-HETE) and 15-HETE were investigated. Dose-dependent increases in the levels of IL-1alpha and HETEs were observed in the underlying medium of the skin systems exposed to two skin irritants, glutaraldehyde and SLS. The results of the present study show that both human artificial skins can be used as efficient testing models for the evaluation of skin toxicity in vitro and for screening the contact skin irritancy in vitro.

Simultaneous saccharification and fermentation of cellulosic biomass to acetic acid.

A strain of Clostridium thermoaceticum (ATCC 49707) was evaluated for its homoacetate potential. This thermophilic anaerobe best produces acetate from glucose at pH 6.0 and 59 degrees C with a yield of 83% of theoretical. Enzyme hydrolysis of two substrates, a-cellulose and a pulp mill sludge, yielded 68% and 70% digestion, respectively. The optimum conditions for the simultaneous saccharification and fermentation (SSF) were substrate dependent: 55 degrees C, pH 6.0 for alpha-cellulose, and 55 degrees C, pH 5.5 for the pulp mill sludge. In the SSF with alpha-cellulose, the overall yield of acetate was strongly influenced by the enzyme loading. In a fed-batch operation of SSF with alpha-cellulose, an overall acetic acid yield of 60 wt% was obtained. Among the factors limiting the yields were incomplete digestion by the enzyme and the end-product inhibition. In the SSF of pulp mill sludge, inhibitors present in the sludge severely limited bacterial action. A large accumulation of glucose developed over the entire process, changing the intended SSF operation into a separate hydrolysis and fermentation operation. Despite a long lag phase of microbial growth, a terminal yield of 85% was obtained with this substrate.