Integrating single-cell and spatial transcriptomics reveals endoplasmic reticulum stress-related CAF subpopulations associated with chordoma progression

BACKGROUND

With cancer-associated fibroblasts (CAFs) as the main cell type, the rich myxoid stromal components in chordoma tissues may likely contribute to its development and progression.

METHODS

Single-cell RNA sequencing (scRNA-seq), spatial transcriptomics, bulk RNA-seq, and multiplexed quantitative immunofluorescence (QIF) were used to dissect the heterogeneity, spatial distribution, and clinical implication of CAFs in chordoma.

RESULTS

We sequenced here 72 097 single cells from 3 primary and 3 recurrent tumor samples, as well as 3 nucleus pulposus samples as controls using scRNA-seq. We identified a unique cluster of CAF in recurrent tumors that highly expressed hypoxic genes and was functionally enriched in endoplasmic reticulum stress (ERS). Pseudotime trajectory and cell communication analyses showed that this ERS-CAF subpopulation originated from normal fibroblasts and widely interacted with tumoral and immune cells. Analyzing the bulk RNA-seq data from 126 patients, we found that the ERS-CAF signature score was associated with the invasion and poor prognosis of chordoma. By integrating the results of scRNA-seq with spatial transcriptomics, we demonstrated the existence of ERS-CAF in chordoma tissues and revealed that this CAF subtype displayed the most proximity to its surrounding tumor cells. In subsequent QIF validation involving 105 additional patients, we confirmed that ERS-CAF was abundant in the chordoma microenvironment and located close to tumor cells. Furthermore, both ERS-CAF density and its distance to tumor cells were correlated with tumor malignant phenotype and adverse patient outcomes.

CONCLUSIONS

These findings depict the CAF landscape for chordoma and may provide insights into the development of novel treatment approaches.

Cardiovascular-specific mortality and risk factors in colorectal Cancer patients: A cohort study based on registry data of over 500,000 individuals in the US

BACKGROUND

Colorectal cancer (CRC) is one of the most common cancers worldwide, and recent studies have found that CRC patients are at increased risk for cardiovascular disease (CVD). This study aimed to investigate competing causes of death and prognostic factors among a large cohort of CRC patients and to describe cardiovascular-specific mortality in relation to the US standard population.

METHODS

This registry-based cohort study identified patients diagnosed with CRC between 1973 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database in the US. Cumulative mortality functions, conditional standardized mortality ratios, and cause-specific hazard ratios were calculated.

RESULTS

Of the 563,298 eligible CRC patients included in this study, 407,545 died during the follow-up period. CRC was the leading cause of death, accounting for 49.8% of all possible competing causes of death. CVD was the most common non-cancer cause of death, accounting for 17.8% of total mortality. This study found that CRC patients have a significantly increased risk of cardiovascular-specific mortality compared to the US standard population, with the risk increasing with age and extended survival time.

CONCLUSION

This study highlights the need to develop multidisciplinary prevention and management strategies for CRC and CVD to improve CRC patients' survival and quality of life.

A novel immune checkpoint-related signature for prognosis and immune analysis in breast cancer

Breast cancer is one of the most prevailing forms of cancer globally. Immunotherapy has demonstrated efficacy in improving the overall survival of breast cancer. The aim of us was to formulate a novel signature predicated on immune checkpoint-related genes (ICGs) that could anticipate the prognosis and further analyze the immune status of patients with breast cancer. After acquiring data, we pinpointed the definitive ICGs for constructing the prognostic model of breast cancer. We constructed a novel prognostic model and created a fresh risk score called Immune Checkpoint-related Risk Score in breast cancer (ICRSBC). The nomogram was constructed to evaluate the accuracy of the model, and the new web-based tool was created to be more intuitive for predicting prognosis. We also investigated immunotherapy responsiveness and analyzed the tumor mutational burden (TMB) in ICRSBC subgroups. The ICRSBC was found to have significant correlations with the immune environment, immunotherapy responsiveness, and TMB. The expression levels of the 9 ICGs that construct the prognostic model and their promoter methylation levels are significantly different between breast cancer and normal tissues. Furthermore, the mutation profiles, the copy number alterations, and the levels of protein expression also exhibit marked disparities among the 9 ICGs. We have identified and validated a novel signature related to ICGs that is strongly associated with breast cancer progression. This signature enables us to create a risk score for prognosticating the survival and assessing the immune status of individuals affected by breast cancer.

High-Density IgG4+ Plasma Cells Infiltration Is Associated With Fibroplasia in Fibrostenotic Crohn's Disease

Transmural fibrosis and stricture formation are key pathogenic processes for Crohn's disease that underlies clinical refractoriness, resulting in severe morbidity. The mechanisms for fibroplasia in Crohn's are not fully elucidated. In this study, we identified a cohort of refractory Crohn's disease with surgically resected bowel specimens including cases with bowel stricture and age-/sex-matched refractory disease without bowel stricture. Via immunohistochemistry, density and distribution of IgG4+ plasma cells in resected cases were analyzed. The histologic severity of fibrosis and association with gross evidence of stricture formation and IgG4+ plasma cells were comprehensively analyzed. Our results showed that density of IgG4+ plasma cells/high-power field (IgG4+ PCs/HPF) was significantly associated with increasing histologic fibrosis score (15 IgG4+ PCs/HPF in specimens with fibrosis score 0 vs 31 IgG4+ PC/HPF in fibrosis score 2 and 3, P = .039). Patients with gross evidence of stricture had significantly higher fibrosis scores compared to those without gross evidence of stricture (P = .044). There was a trend that mean IgG4+ plasma cell count was higher in Crohn's disease with gross stricture formation (P = .26), although it did not reach statistical significance (likely due to multiple pathogenesis events involved in bowel stricture formation besides IgG4+ plasma cells; such as transmural fibrosis, muscular hypertrophy, transmural ulcer/scar formation, and muscular-neural dysfunction). Our findings indicate IgG4+ plasma cells are associated with increasing histologic fibrosis in Crohn's. Further research is needed to establish a role for IgG4+ plasma cells in fibroplasia with an eye toward potential medical therapies targeting IgG4+ plasma cells to prevent transmural fibrosis.

Over-expression of Programmed Death Ligand 1 (PD-L1) in Refractory Inflammatory Bowel Disease (IBD)

Programmed death ligand 1 (PD-L1) dysregulation has been implicated in chronic inflammatory diseases, but its role in regulating intestinal mucosa inflammation is still unclear. The aim of this study was to assess PD-L1 expression in the intestinal mucosa of patients with refractory inflammatory bowel disease (IBD) compared to controls. We evaluated PD-L1 expression by immunohistochemistry in colectomy specimens of patients with ulcerative colitis (UC) and Crohn disease (CD) compared to controls. PD-L1 expression was assessed in colonic epithelium and inflammatory cells, along with the location of the inflammatory cells expressing PD-L1. All cases were stained with CD3, CD4, CD8, FOXP3, CD20, CD68, and CD90 immunostains to determine the types of cells expressing PD-L1. The UC group showed significantly higher PD-L1 expression in the colonic epithelium compared to both CD and control groups (both P<0.001), and CD was also significantly higher than the control group (P=0.004). Both UC and CD groups showed similar PD-L1 expression in the inflammatory infiltrate, but significantly higher than the control group (both P<0.001). Among both IBD groups, higher IBD activity was associated with higher levels of PD-L1 expression in the colonic epithelium (P<0.05) and inflammatory infiltrate (P<0.001). When comparing PD-L1 expression to lineage specific markers, CD3+, CD4+ T cells, CD68+ macrophages, and CD90+ colonic stromal cells appeared to be expressing PD-L1. These findings implicate a role for PD-L1 in the dysregulation of the immune response in refractory IBD. Further studies are warranted to better understand the role of the immune regulatory pathways in intestinal mucosa.

Clinicopathologic Characteristics of FBXW7-Mutated Colorectal Adenocarcinoma and Association with Aberrant Beta-catenin Localization

Oncogenic mutations in the adenomatous polyposis coli (APC)/Wnt signaling pathway are well documented. The FBXW7 gene (F-Box And WD Repeat Domain Containing 7) encodes a member of the ubiquitin-proteasome complex that is more recently described to antagonize the oncogenic Wnt pathway by promoting the degradation of β-catenin encoded by CTNNB1 gene. The pathologic significance of FBXW7 mutation in colorectal carcinoma (CRC) remains underreported. In this study, we report the clinicopathologic and β-catenin immunohistochemical features of a single-institution cohort (83 cases) of FBXW7-mutated CRC compared to CTNNB1-mutated CRC. FBXW7-mutated CRC was more common in older patients (p=0.031) and in the left/distal colon (p=0.022). Immunohistochemical analysis revealed that aberrant nuclear/cytoplasmic β-catenin localization was identified in a significantly high proportion of FBXW7-mutated CRCs. When compared to CTNNB1-mutated CRC, FBXW7-mutated CRC showed a significantly higher proportion of MSI-stable tumors with intact expression of DNA mismatch repair proteins, and had significantly more frequent co-occurrence of missense TP53 and KRAS mutations. The most frequently mutated FBXW7 residues/hotspots were located within the WD repeat domains (aa 378-659), which were also associated with aberrant nuclear/cytoplasmic localization of β-catenin protein. Our results indicate the unique pathologic characteristics of FBXW7 mutated CRC with frequent co-occurrence of missense mutant TP53, and KRAS. The mutated FBXW7 residues/hotspots and its association with aberrant nuclear/cytoplasmic β-catenin localization further support the oncogenic role of FBXW7 in colon carcinogenesis.

Unique clinicopathologic and genetic alteration features in early onset colorectal carcinoma compared with age-related colorectal carcinoma: a large cohort next generation sequence analysis

Colorectal carcinoma (CRC) is the third most common cancer type in the United States. While the incidence of CRC is decreasing among an older population undergoing screening, the incidence of early-onset CRC is rising. There is a growing understanding that the molecular underpinnings of colorectal carcinoma vary by age. In this study, we report the genetic alterations and clinicopathologic features of a single-institution colorectal carcinoma cohort over a 2-year period using a next-generation sequencing (NGS) approach and microsatellite stability (MS) status determined by immunohistochemical staining. Forty cases were identified in an early-onset colorectal carcinoma cohort (eCRC) defined by age <40 years, and 164 cases were identified in an age-related colorectal carcinoma cohort (arCRC) defined by age >70 years. eCRC was more often-left-sided/rectal and more likely to present high rates of lymph node positivity with metastatic disease. NGS mutational analysis revealed distinct differences between eCRC and arCRC, with eCRC being characterized by low frequency of PIK3CA mutations, elevated frequency of KRAS and CTNNB1 mutations in microsatellite instability high tumors, and very low frequency of BRAF mutations.

A four-factor immune risk score signature predicts the clinical outcome of patients with spinal chordoma

BACKGROUND

Currently, the measurement of immune cells in previous studies is usually subjective, and no immune-based prognostic model has been established for chordoma. In this study, we sought to simultaneously measure tumor-infiltrating lymphocyte (TIL) subtypes in chordoma samples using an objective method and develop an immune risk score (IRS) model for survival prediction.

METHODS

Multiplexed quantitative immunofluorescence staining was used to determine the TIL levels in the tumoral and stromal subareas of 114 spinal chordoma specimens (54 in the training and 60 in the validation cohort) for programmed death-1 (PD-1), CD3, CD8, CD20 (where CD is cluster of differentiation), and FOXP3. Flow cytometry was performed to validate the immunofluorescence assay for lymphocyte measurement on an additional five fresh chordoma specimens. Subsequently, the IRS model was built using the least absolute shrinkage and selection operator (LASSO) Cox regression method.

RESULTS

Flow cytometry and quantitative immunofluorescence showed similar lymphocytic percentages and TIL subpopulation proportions in the fresh tumor specimens. With the training data, the LASSO model identified four immune features for IRS construction: tumoral FOXP3, tumoral PD-1, stromal FOXP3, and stromal CD8. In both cohorts, a high IRS was significantly associated with tumoral programmed cell death-1 ligand 1 expression, Enneking inappropriate tumor resection, and surrounding muscle invasion by tumor. Multivariate Cox regression and stratified analysis in the two cohorts revealed that the IRS was an independent predictor and could effectively separate patients with similar Enneking staging into different risk subgroups, with significantly different survival rates. Further receiver operating characteristic analysis found that the IRS classifier had a better prognostic value than the traditional clinicopathological factors and compensated for the deficiency of Enneking staging for outcome prediction. More importantly, a nomogram based on the IRS and clinical predictors showed adequate performance in estimating disease recurrence and survival of patients.

CONCLUSIONS

These data support the use of the IRS signature as a reliable prognostic tool in spinal chordoma and may facilitate individualized therapy decision making for patients.

SALL2 represses cyclins D1 and E1 expression and restrains G1/S cell cycle transition and cancer-related phenotypes

SALL2 is a poorly characterized transcription factor that belongs to the Spalt‐like family involved in development. Mutations on SALL2 have been associated with ocular coloboma and cancer. In cancers, SALL2 is deregulated and is proposed as a tumor suppressor in ovarian cancer. SALL2 has been implicated in stemness, cell death, proliferation, and quiescence. However, mechanisms underlying roles of SALL2 related to cancer remain largely unknown. Here, we investigated the role of SALL2 in cell proliferation using mouse embryo fibroblasts (MEFs) derived from Sall2^−/− mice. Compared to Sall2^+/+ MEFs, Sall2^−/− MEFs exhibit enhanced cell proliferation and faster postmitotic progression through G1 and S phases. Accordingly, Sall2^−/− MEFs exhibit higher mRNA and protein levels of cyclins D1 and E1. Chromatin immunoprecipitation and promoter reporter assays showed that SALL2 binds and represses CCND1 and CCNE1 promoters, identifying a novel mechanism by which SALL2 may control cell cycle. In addition, the analysis of tissues from Sall2^+/+ and Sall2^−/− mice confirmed the inverse correlation between expression of SALL2 and G1‐S cyclins. Consistent with an antiproliferative function of SALL2, immortalized Sall2^−/− MEFs showed enhanced growth rate, foci formation, and anchorage‐independent growth, confirming tumor suppressor properties for SALL2. Finally, cancer data analyses show negative correlations between SALL2 and G1‐S cyclins’ mRNA levels in several cancers. Altogether, our results demonstrated that SALL2 is a negative regulator of cell proliferation, an effect mediated in part by repression of G1‐S cyclins’ expression. Our results have implications for the understanding and significance of SALL2 role under physiological and pathological conditions.

A Trichostatin A (TSA)/Sp1-mediated mechanism for the regulation of SALL2 tumor suppressor in Jurkat T cells

SALL2 is a transcription factor involved in development and disease. Deregulation of SALL2 has been associated with cancer, suggesting that it plays a role in the disease. However, how SALL2 is regulated and why is deregulated in cancer remain poorly understood. We previously showed that the p53 tumor suppressor represses SALL2 under acute genotoxic stress. Here, we investigated the effect of Histone Deacetylase Inhibitor (HDACi) Trichostatin A (TSA), and involvement of Sp1 on expression and function of SALL2 in Jurkat T cells. We show that SALL2 mRNA and protein levels were enhanced under TSA treatment. Both, TSA and ectopic expression of Sp1 transactivated the SALL2 P2 promoter. This transactivation effect was blocked by the Sp1-binding inhibitor mithramycin A. Sp1 bound in vitro and in vivo to the proximal region of the P2 promoter. TSA induced Sp1 binding to the P2 promoter, which correlated with dynamic changes on H4 acetylation and concomitant recruitment of p300 or HDAC1 in a mutually exclusive manner. Our results suggest that TSA-induced Sp1-Lys703 acetylation contributes to the transcriptional activation of the P2 promoter. Finally, using a CRISPR/Cas9 SALL2-KO Jurkat-T cell model and gain of function experiments, we demonstrated that SALL2 upregulation is required for TSA-mediated cell death. Thus, our study identified Sp1 as a novel transcriptional regulator of SALL2, and proposes a novel epigenetic mechanism for SALL2 regulation in Jurkat-T cells. Altogether, our data support SALL2 function as a tumor suppressor, and SALL2 involvement in cell death response to HDACi.

Sall2 is required for proapoptotic Noxa expression and genotoxic stress-induced apoptosis by doxorubicin

The Sall2 transcription factor is deregulated in several cancers; however, little is known about its cellular functions, including its target genes. Recently, we demonstrated that p53 directly regulates Sall2 expression under genotoxic stress. Here, we investigated the role of Sall2 in the context of cellular response to genotoxic stress. In addition, we further examined the Sall2-p53 relationship during genotoxic stress in primary mouse embryo fibroblasts (MEFs), which are derived from Sall2 knockout mice separately, or in combination with the p53ERTAM knock-in mice. We found that the levels of Sall2 mRNA and protein are dynamically modulated in response to doxorubicin. At early times of stress, Sall2 is downregulated, but increases under extension of the stress in a p53-independent manner. Based on caspase-3/7 activities, expression of cleaved poly (ADP-ribose) polymerase, expression of cleaved caspase-3 and induction of proapoptotic proteins, Sall2 expression was correlated with cellular apoptosis. Consequently, Sall2-/- MEFs have decreased apoptosis, which relates with increased cell viability in response to doxorubicin. Importantly, Sall2 was required for apoptosis even in the presence of fully activated p53. Searching for putative Sall2 targets that could mediate its role in apoptosis, we identified proapoptotic NOXA/PMAIP1 (phorbol-12-myristate-13-acetate-induced protein 1). We demonstrated that Sall2 positively regulates Noxa promoter activity. Conserved putative Sall2-binding sites at the NOXA promoter were validated in vitro by electrophoretic mobility shift assay and in vivo by ChIP experiments, identifying NOXA as a novel Sall2 target. In agreement, induction of Noxa protein and mRNA in response to doxorubicin was significantly decreased in Sall2-/- MEFs. In addition, studies in leukemia Jurkat T cells support the existence of the Sall2/Noxa axis, and the significance of this axis on the apoptotic response to doxorubicin in cancer cells. Our study highlights the relevance of Sall2 in the apoptotic response to extended genotoxic stress, which is important for understanding its role in normal physiology and disease.

Wild type p53 transcriptionally represses the SALL2 transcription factor under genotoxic stress

SALL2- a member of the Spalt gene family- is a poorly characterized transcription factor found deregulated in various cancers, which suggests it plays a role in the disease. We previously identified SALL2 as a novel interacting protein of neurotrophin receptors and showed that it plays a role in neuronal function, which does not necessarily explain why or how SALL2 is deregulated in cancer. Previous evidences indicate that SALL2 gene is regulated by the WT1 and AP4 transcription factors. Here, we identified SALL2 as a novel downstream target of the p53 tumor suppressor protein. Bioinformatic analysis of the SALL2 gene revealed several putative p53 half sites along the promoter region. Either overexpression of wild-type p53 or induction of the endogenous p53 by the genotoxic agent doxorubicin repressed SALL2 promoter activity in various cell lines. However R175H, R249S, and R248W p53 mutants, frequently found in the tumors of cancer patients, were unable to repress SALL2 promoter activity, suggesting that p53 specific binding to DNA is important for the regulation of SALL2. Electrophoretic mobility shift assay demonstrated binding of p53 to one of the identified p53 half sites in the Sall2 promoter, and chromatin immunoprecipitation analysis confirmed in vivo interaction of p53 with the promoter region of Sall2 containing this half site. Importantly, by using a p53ER (TAM) knockin model expressing a variant of p53 that is completely dependent on 4-hydroxy-tamoxifen for its activity, we show that p53 activation diminished SALL2 RNA and protein levels during genotoxic cellular stress in primary mouse embryo fibroblasts (MEFs) and radiosensitive tissues in vivo. Thus, our finding indicates that p53 represses SALL2 expression in a context-specific manner, adding knowledge to the understanding of SALL2 gene regulation, and to a potential mechanism for its deregulation in cancer.

Abstract LB-51: p53 transcriptionally represses the SALL2 transcription factor under genotoxic stress

SALL2- a member of the Spalt gene family- is a poorly characterized transcription factor found deregulated in various cancers, which suggest it plays a role in the disease. We previously identified SALL2 as a novel interacting protein of neurotrophin receptors and showed that it plays a role in neuronal function, which does not necessarily explain why or how SALL2 is deregulated in cancer. Previous evidences indicate that SALL2 gene is regulated by the WT1 and AP4 transcription factors. Here, we identified SALL2 as a novel downstream target of the P53 tumor suppressor protein. Bioinformatic analysis of the SALL2 gene revealed several putative P53 half sites along the promoter region. Either overexpression of wild-type P53 or induction of the endogenous P53 by the genotoxic agent doxorubicin repressed SALL2 promoter activity in various cell lines. However, Q143A, R175H and R248W P53 mutants, which are frequently found in the tumors of cancer patients, were unable to repress SALL2 promoter activity. Chromatin immunoprecipitation analysis using a specific P53 antibody further supported the binding to, and regulation of the SALL2 promoter by P53. Importantly, by using a p53ERTAM knockin model expressing a variant of P53 that is completely dependent on 4-hydroxy-tamoxifen for its activity, we show that P53 activation diminished SALL2 RNA and protein levels during genotoxic cellular stress in primary mouse embryo fibroblasts (MEFs) and radiosentive tissues in vivo. Thus, our finding indicates that P53 represses SALL2 expression in a context-specific manner, adding knowledge to understanding SALL2 gene regulation, and a potential mechanism for its deregulation in cancer

Citation Format: Carlos Farkas, Carla Martins, David Escobar, Ariel Castro, David Donner, Roxana Pincheira. p53 transcriptionally represses the SALL2 transcription factor under genotoxic stress. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-51. doi:10.1158/1538-7445.AM2013-LB-51

Essential role of intracellular glutathione in controlling ascorbic acid transporter expression and function in rat hepatocytes and hepatoma cells

Although there is in vivo evidence suggesting a role for glutathione in the metabolism and tissue distribution of vitamin C, no connection with the vitamin C transport systems has been reported. We show here that disruption of glutathione metabolism with buthionine-(S,R)-sulfoximine (BSO) produced a sustained blockade of ascorbic acid transport in rat hepatocytes and rat hepatoma cells. Rat hepatocytes expressed the Na(+)-coupled ascorbic acid transporter-1 (SVCT1), while hepatoma cells expressed the transporters SVCT1 and SVCT2. BSO-treated rat hepatoma cells showed a two order of magnitude decrease in SVCT1 and SVCT2 mRNA levels, undetectable SVCT1 and SVCT2 protein expression, and lacked the capacity to transport ascorbic acid, effects that were fully reversible on glutathione repletion. Interestingly, although SVCT1 mRNA levels remained unchanged in rat hepatocytes made glutathione deficient by in vivo BSO treatment, SVCT1 protein was absent from the plasma membrane and the cells lacked the capacity to transport ascorbic acid. The specificity of the BSO treatment was indicated by the finding that transport of oxidized vitamin C (dehydroascorbic acid) and glucose transporter expression were unaffected by BSO treatment. Moreover, glutathione depletion failed to affect ascorbic acid transport, and SVCT1 and SVCT2 expression in human hepatoma cells. Therefore, our data indicate an essential role for glutathione in controlling vitamin C metabolism in rat hepatocytes and rat hepatoma cells, two cell types capable of synthesizing ascorbic acid, by regulating the expression and subcellular localization of the transporters involved in the acquisition of ascorbic acid from extracellular sources, an effect not observed in human cells incapable of synthesizing ascorbic acid.

An hypothesis on pressure transmission from anterior chamber to optic nerve

Few studies have characterized how pressure in the anterior chamber (AC) of the eye is transmitted via the vitreous to the vitreous-ganglion cell interface. We are aware of only one study that simultaneously measured the pressures in the AC and vitreous humor; and of only one study that simultaneously measured the pressures in the AC and the suprachoroidal space (SCS). The pressure in the AC is defined as the intraocular pressure (IOP), which when elevated beyond statistically normal limits is a recognized risk factor for glaucoma, a malady best described as an optic neuropathy with degeneration and eventual death of the retinal ganglion cells (GC's) and highly characteristic changes in the optic nerve head (ONH). Most investigators currently believe that the prevalent risk factor for GC apoptosis is ocular hypertension, but no one has demonstrated how an increase in IOP in the AC is transmitted to the GC's. In patients with primary open angle glaucoma, the pressure in the AC increases due to an increase in the resistance of the trabecular meshwork (TM) outflow pathway. We questioned how such increased pressure in the AC would be transmitted to the GC to produce the changes in the ONH seen in glaucoma. Based on our preliminary data and purview of the literature, we hypothesize that a pressure increase originating in the AC is likely transmitted via both the SCS and the vitreous, with transmission via the former pathway probably most efficient in affecting the GC. Independently of the mechanism that produces GC apoptosis, the ones that are first affected, as repeatedly shown by visual field tests, are the most peripheral ones; i.e., those whose axons are the most external as they form the ONH and enter the lamina cribrosa. There are no published reports explaining this peculiarity. The dogma is that the pressure transmitted via the vitreous is higher at the periphery because it is transmitted across a shorter distance, since the vitreous acts as a buffer that absorbs part of the pressure being transmitted. We propose that IOP is not only transmitted via the vitreous but also via the SCS. Increases in IOP could be efficiently applied via the SCS to the most external axons of the ONH as they leave the eye. Our hypothesis can also explain low-tension glaucoma in which the most peripheral GC's are also affected first, because pressure is transmitted without decay due to a reduced uveoscleral (UVS) flow.

High-pressure homogenization of raw and pasteurized milk modifies the yield, composition, and texture of queso fresco cheese

High-pressure homogenization (HPH) of milk was studied as an alternative processing operation in the manufacturing of queso fresco cheese. Raw and pasteurized (65°C for 30 min) milks were subjected to HPH at 0, 100, 200, and 300 MPa and then used to manufacture queso fresco. The cheeses were evaluated for yield, moisture content, titratable acidity, nitrogen content, whey protein content, yield force, yield strain, and tactile texture by instrumental or trained panel analyses. The combination of HPH and thermal processing of milk resulted in cheeses with increased yield and moisture content. The net amount of protein transferred to the cheese per kilogram of milk remained constant for all treatments except raw milk processed at 300 MPa. The highest cheese yield, moisture content, and crumbliness were obtained for thermally processed milk subjected to HPH at 300 MPa. The principal component analysis of all measured variables showed that the variables yield, moisture content, and crumbliness were strongly correlated to each other and negatively correlated to the variables yield strain, protein content (wet basis), and sensory cohesiveness. It is suggested that the combination of thermal processing and HPH promotes thermally induced denaturation of whey protein, together with homogenization-induced dissociation of casein micelles. The combined effect results in queso fresco containing a thin casein-whey matrix that is able to better retain sweet whey. These results indicate that HPH has a strong potential for the manufacture of queso fresco with excellent yield and textural properties.

The impact of malnutrition on morbidity, mortality and length of hospital stay in trauma patients

BACKGROUND AND AIM

To asses the nutritional status of hospitalised trauma patients and the repercussion on the clinical follow up.

METHODS

In a prospective way 161 adult patients admitted to the units of Intensive Care (ICU), General Surgery, Maxillofacial Surgery and Orthopedics of the Centro de Emergencias Médicas in Asunción, Paraguay, from March 2002 to March 2004 were evaluated at admission by using the Subjective Global Assessment (SGA). Patients were followed to determine length of hospital stay, complications and in-hospital mortality.

RESULTS

From the trauma patients median age was 27 (14-92) years and 94% were males. Most patients (74%) were from the countryside. The most frequent anatomic sites of trauma were: head 25%, thorax 16.6%, limbs 15.4%, abdomen 14%. The median Injury Severity Score (ISS) was 20 (1-39). From this population of patients, 40% were malnourished or at risk of malnutrition according to the SGA. Multivariate analysis identified as significant risk factors for mortality: malnutrition according to the SGA (p = 0.04, RR = 4 (1-15), and admission to the ICU (p = 0.0001, RR 53 (12-234). Risk factors for complications were malnutrition according to the SGA (p = 0.003, RR 2.9 (1.4-5.8) and ISS over 20 (p = 0.001, RR = 8.4 (2.3-29.9). The risk factors for length of stay were malnutrition according to the Subjective Global Assesment (p = 0.01, RR = 2.3 (1.2-4.7) and Injury Severity Score over 20, p = 0.03, RR = 2.8 (1-7.3).

CONCLUSIONS

In the conditions of this study, malnutrition is frequent on admission in trauma patients, and is an independent risk factor for morbidity, mortality, and prolongs the length of hospitalisation. Efforts should be made to quickly assess the nutritional status of these patients and early start nutritional intervention.

Modulation of rat liver cytochrome P450 by protein restriction assessed by biochemical and bacterial mutagenicity methods [corrected]

Protein restriction (PR) significantly inhibits spontaneous and chemical carcinogenesis. Several factors seem to be involved in this effect, including a decrease in body weight, cellular proliferation and DNA damage and an increase in antioxidant defenses. The current study was designed to determine modifications in some hepatic cytochromes P450 (CYPs) due to a hypoproteic diet and to investigate its implications on chemical mutagenesis. Western blot analysis showed decreases of 73, 40 and 74% in CYP1A, CYP2B and CYP2E1 protein concentrations in hepatic microsomes from animals fed a protein-restricted (6% protein) diet for 6 weeks in comparison with microsomes from rats fed a 24% protein diet during the same period. In the same way, low protein fed animals showed a 3.5-fold decrease in hepatic CYP1A1-associated ethoxyresorufin O-deethylase activity, a 6-fold decrease in CYP1A2-associated methoxyresorufin O-demethylase activity, a 1.7-fold decrease in CYP2B1-associated penthoxyresorufin O-dealkylase activity, a 9-fold decrease in CYP2B2-associated benzyloxyresorufin O-dealkylase and, finally, a 3.4-fold decrease in CYP2E1-associated 4-nitrophenol hydroxylase activity. As a result of decreased CYP hepatic protein concentrations and enzymatic activities, liver S9 from rats fed a hypoproteic diet was less efficient in activating promutagens than S9 prepared from rats fed a 24% protein diet in the Ames test. Mutagenic potency obtained with protein-restricted S9 was reduced 25-fold for 2-aminoanthracene, 1.5-fold for N-nitrosodipropylamine, 12.5-fold for N-nitrosodibutylamine, 2-fold for cyclophosphamide and N-nitrosopyrrolidine and 71-fold for N-nitrosodimethylamine. However, the mutagenic potency of benzo[a]pyrene was the same (4 revertants/ microg) with S9 derived from rats fed either a 6 or 24% protein diet.

[Seroprevalence of delta infection in a group of patients with HBsAg positive in the city of Maracaibo]

In order to establish a preliminary information about the penetration of delta infection in our population, 40 HBsAg positive sera were tested for antidelta. 20 were asymptomatic patients and 20 were symptomatics. In the group of asymptomatic patients 3 belong to a high risk population: 1 homosexual, 1 dialysis patient, 1 nurse of dialysis unit. None of the patients of this group were positive for antidelta. In the group of symptomatics one was positive for antidelta. It's represents a seroprevalence of 5%. This patient was an indian who lives in the city but was born in Perijá where severe epidemics have been reported. These results support that the infection seems to be restricted to this indigenous group but the spread must be considered because the patient was living in the city. In addition, the use of antidelta as the unique serologic marker should undervalue the real prevalence of infection in the cases of acute hepatitis, which represent the majority of symptomatics patients. In consequence the paper of delta agent must be considered in the genesis of hepatitis in our population as well as its further epidemiologic course.

Enhanced tumor metastases upon drug delivery in cross-linked albumin beads

Growth of the murine hepatoma H6 was significantly suppressed by amiloride, a sodium influx inhibitor. Primary tumor growth inhibition was augmented by loading the drug into cross-linked albumin carriers, but lung metastases were enhanced. These results emphasize the importance of using metastatic tumor models when testing new drugs and/or alternative modes of drug delivery.