Perceptions of palliative care in Huntington's disease: A qualitative study

INTRODUCTION

Palliative care focuses on improving patient and family quality of life by managing symptoms, psychosocial issues and spiritual concerns. Huntington's disease is a progressive neurodegenerative disorder with no current disease modifying therapy. Although the palliative care model has been postulated to be an integral part of HD care, there are gaps in knowledge about how this care should be implemented. This study aims to identify perceptions of palliative care in Huntington's Disease (HD), palliative care needs of people living with HD, and at what point they feel they would benefit from these resources.

METHODS

Participants volunteered from a large academic institution patient base to be involved in semi structured interviews that explored patient and caregiver experience surrounding their diagnosis, disease management, quality of life, and areas for improvement. Inclusion criteria for participants was a diagnosis of Huntington's disease and/or a self-identified caregiver of a person living with the disease.

RESULTS

A total of 12 independent patients, three independent caregivers, and five dyads completed the interviews. Themes identified included needs that would provide patient and caregiver centered treatment, current gaps in care, an openness and desire for palliative care, and knowledge about the desired timing of palliative care in treatment plans.

CONCLUSION

People living with HD and caregivers of people with HD most desire access to treatment that would focus on symptom management, availability of social resources, advanced care planning and spiritual wellbeing. The preferred timing of this intervention for most individuals would be at the onset of symptoms.

Atmospheric pollution, soil nutrients and climate effects on Mucoromycota arbuscular mycorrhizal fungi

Fine root endophyte mycorrhizal fungi in the Endogonales (Mucoromycota arbuscular mycorrhizal fungi, M‐AMF) are now recognized as at least as important globally as Glomeromycota AMF (G‐AMF), yet little is known about the environmental factors which influence M‐AMF diversity and colonization, partly because they typically only co‐colonize plants with G‐AMF. Wild populations of Lycopodiella inundata predominantly form mycorrhizas with M‐AMF and therefore allow focussed study of M‐AMF environmental drivers. Using microscopic examination and DNA sequencing we measured M‐AMF colonization and diversity over three consecutive seasons and modelled interactions between these response variables and environmental data. Significant relationships were found between M‐AMF colonization and soil S, P, C:N ratio, electrical conductivity, and the previously overlooked micronutrient Mn. Estimated N deposition was negatively related to M‐AMF colonization. Thirty‐nine Endogonales Operational Taxonomic Units (OTUs) were identified in L. inundata roots, a greater diversity than previously recognized in this plant. Endogonales OTU richness correlated negatively with soil C:N while community composition was mostly influenced by soil P. This study provides first evidence that M‐AMF have distinct ecological preferences in response to edaphic variables also related to air pollution. Future studies require site‐level atmospheric pollution monitoring to guide critical load policy for mycorrhizal fungi in heathlands and grasslands.

Inactivating Mutations of the IK Gene Weaken Ku80/Ku70-Mediated DNA Repair and Sensitize Endometrial Cancer to Chemotherapy

IK is a mitotic factor that promotes cell cycle progression. Our previous investigation of 271 endometrial cancer (EC) samples from the Cancer Genome Atlas (TCGA) dataset showed IK somatic mutations were enriched in a cluster of patients with high-grade and high-stage cancers, and this group had longer survival. This study provides insight into how IK somatic mutations contribute to EC pathophysiology. We analyzed the somatic mutational landscape of IK gene in 547 EC patients using expanded TCGA dataset. Co-immunoprecipitation and mass spectrometry were used to identify protein interactions. In vitro and in vivo experiments were used to evaluate IK's role in EC. The patients with IK-inactivating mutations had longer survival during 10-year follow-up. Frameshift and stop-gain were common mutations and were associated with decreased IK expression. IK knockdown led to enrichment of G2/M phase cells, inactivation of DNA repair signaling mediated by heterodimerization of Ku80 and Ku70, and sensitization of EC cells to cisplatin treatment. IK/Ku80 mutations were accompanied by higher mutation rates and associated with significantly better overall survival. Inactivating mutations of IK gene and loss of IK protein expression were associated with weakened Ku80/Ku70-mediated DNA repair, increased mutation burden, and better response to chemotherapy in patients with EC.

Abstract PO-127: Single-cell liquid biopsy reveals circulating heterogeneity and converging subpopulations in relation to immunotherapy response in melanoma

Though treatment with immune checkpoint blockage (ICB) has greatly improved clinical outcomes, not all patients respond to this treatment. Being able to predict which patients are likely to respond would be a significant clinical advance. Thus there remains a need for predictive biomarkers to determine in advance those with the most potential to benefit from immune checkpoint blockade. To date, most biomarkers of response are identified in tumor tissue, whereas biomarkers that can be assessed from peripheral blood are more desirable, due to the ease of access and reproducibility of sampling. To identify biomarkers associated with ICB response from peripheral blood, we apply single cell RNA sequencing to 24 peripheral blood mononuclear cell (PBMC) samples, collected from 12 stage III and IV melanoma patients before and after treatment with anti-PD1 monotherapy. Among these 12 patients, 6 are responders and 6 are non-responders. After quality control, a total of 62,273 single cells remains for further analysis. To define the cell type landscape in an unbiased manner, unsupervised clustering is used. We identify 20 robust cell clusters, including two B cell clusters (B-cell_1; B-cell_2), three myeloid clusters (monocytes, myeloid-derived suppressor cells, and M2 macrophages), twelve clusters enriched for T/NK cells, two clusters of platelets, and Hematopoietic Stem and Progenitor Cells (HSPCs). Across all patients, cell composition differs between pre- and post-treatment samples. Strikingly, responders have significant greater proportions of B-cell_1 cells in their pre-treatment samples than non-responders. At gene level, our analysis identifies an individual overexpressed marker in B-cell_1, i.e. IGLC3, which is highly enriched in responders than non-responders before treatment. In summary, our analysis identifies specific cell type and gene within patients’ PBMC samples that can serve as predictive biomarkers for patient’s response to ICB.

Citation Format: Qianqian Song, Elizabeth Forbes, Lance D. Miller, Pierre L. Triozzi, Liang Liu, Wei Zhang, David R. Soto-Pantoja. Single-cell liquid biopsy reveals circulating heterogeneity and converging subpopulations in relation to immunotherapy response in melanoma [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-127.

Abstract C001: TP53 mutations reprogram fatty acid metabolism and tumor microenvironment in African American patients with non-small cell lung cancer

Lung cancer is the leading cause of cancer-related death worldwide, with a 5-year survival rate of ~18% (1-3). Non-small cell lung cancer (NSCLC) comprises 85% of all lung cancer cases. Great strides have been made with the development of more advanced diagnosis, prognosis, and treatment strategies. Despite improvements, African American patients (AAs) continue to present with more advanced stages and later-stage metastatic tumors of lung cancer at diagnosis. The severe types of lung cancer can reduce the 5-year survival rate to only 4% (4). The disparities may partially be due to the socioeconomic disadvantages of AAs in receiving cancer services (5). Etiologically, cigarette smoking and exposure to secondhand smoking are leading preventable causes of lung cancer and premature death in the United States (US) (5). Notably, menthol cigarettes, which have been particularly marketed to communities with high AA population (7), can cause deeper inhalation, increased absorption of tobacco toxicants, a higher nicotine dependence and reduced cessation success (6-8). Some genetic alterations have been suggested to contribute to the disparities of breast cancer (9), but genetic factors have not been well studied in lung cancer disparities. Utilizing the genomic data from the Precision Oncology Initiative (POI) cohort at the Wake Forest Baptist Comprehensive Cancer Center (WFBCCC), our initial analysis has shown that TP53 has a significantly higher mutation rate in AA patients, which was validated with the TCGA cohort (10). Furthermore, codons including Cysteine 176 (C176) and C242 mutated more frequently in AA than CA patients. Considering the four amino acids in the zinc-binding region (C176, Histidine 179 [H179], C238, and C242), AA patients have a higher mutation rate than CA patients within both our POI (15% v.s. 5%, P=5E-4) and the TCGA (14% vs. 6%, P<5E-4) cohorts. NSCLC patients with TP53 mutations experienced a poorer survival outcome, and, importantly, mutant AA had shorter overall survival than their CA counterparts. Utilizing RNA-Seq data of NSCLC patients from the TCGA cohort and Gene Set Enrichment Analysis (GSEA), we also identified increased transcriptional activation of fatty acid metabolism and reactive oxygen species (ROS) among TP53 mutation carriers; both pathways/processes are related to an immunosuppressive tumor microenvironment (TME). More importantly, significantly increased expression of these two gene sets was observed in AA cases with TP53 mutations than in their CA counterparts. The immunosuppressive TME in TP53-mutant (vs. wild-type) and mutant AA (vs. CA) patients were further validated by analyzing the immune cell components in each patient using computation algorithm CIBERSORT (11). These analyses implicate that mutated TP53 differentially contributes to cancer disparities in the AA population through metabolism and immune suppression, and mutations in the zinc-binding domain of p53 protein are specifically crucial.

Citation Format: Liang Liu, Farideh Mehraein-Ghomi, Elizabeth Forbes, Umit Topaloglu, W. Jeffrey Petty, Stefan Grant, Jimmy Ruiz, Kristie L. Foley, Karen Winkfield, Boris Pasche, Wei Zhang. TP53 mutations reprogram fatty acid metabolism and tumor microenvironment in African American patients with non-small cell lung cancer [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C001.

Abstract B98: IGFBP2 reprograms pancreatic cancer immune surveillance at epitranscriptome levels

In recent years, checkpoint blockade has been used successfully to treat many cancer types including melanoma, non-small cell lung, and colorectal cancers. In stark contrast, the response to these new immunotherapeutics has been poor in patients with pancreatic ductal adenocarcinoma (PDAC), the most common and lethal type of pancreatic cancer. Thus, PDAC is considered a cold tumor for immunotherapy and the mechanism underlying this resistance is poorly understood. Insulin-like growth factor binding protein-2 (IGFBP2), a secreted cytokine, is elevated in the serum, pancreatic juice, and PDAC tissues in many pancreatic cancer patients, and we demonstrated that high levels associate to reduced overall patient survival and promote the immunosuppressive M2 tumor-associated macrophage phenotype in the tumor microenvironment (TME). We recently identified IGFBP2 as a key oncogenic signaling molecule for PDAC metastasis and epithelial-to-mesenchymal transition. Our preliminary microarray analysis showed that major histocompatibility complex class II antigen (MHC class II) genes were significantly downregulated in AsPC-1 pancreatic cancer cells overexpressing IGFBP2. MHC class II molecules are constitutively expressed in antigen-presenting cells (APCs) such as dendritic and Langerhans cells, macrophages, and B lymphocytes. In PDAC, increased MHC class II expression correlates to a higher histologic grade of differentiation. Also, CD4+ T lymphocyte numbers in PDAC tissues positively correlate to MHC class II expression levels. We envision that high IGFBP2 represses MHC class II gene expression in the tumor-associated APCs, resulting in failure of recruitment and activation of CD4+ lymphocytes, augmenting the immunosuppressive TME. The mechanism whereby IGFBP2 regulates MHC class II gene expression, however, is unknown. IGFBP2 was reported to physically interact with Pim-1-associated protein-1 (PAP-1)-associated protin-1 (PAPA-1) in the nucleus. PAPA-1 (or INO80B) is a key component in the ATP-dependent INO80 chromatin-remodeling complex. A recent study shows that INO80 is required for super-enhancer-mediated oncogenic transcription and tumor growth in melanoma. Interestingly, the MHC class II genes HLA-DR and HLA-DQ were found to be regulated by a super-enhancer mediated mechanism in autoimmune disease. We hypothesized that tumor-secreted IGFBP2 directly regulates INO80 function and inhibits the MHC class II expression in APCs in the TME. Our preliminary data show that exogenous IGFBP2 translocates into the cell nucleus within hours, and co-immunoprecipitation confirmed that IGFBP2 interacts with INO80B in vitro. Furthermore, MHC Class II expression was downregulated by IGFBP2 in the murine DC 2.4 dendritic cell line and in mouse bone marrow-derived dendritic cells by RT-PCR and flow cytometry. Our data suggest that PDAC IGFBP2 levels might predict checkpoint blockade therapy readiness, and importantly, serve as a target mechanism for enabling immunotherapy effectiveness.

Citation Format: Ping-Chieh Chou, Liang Liu, Elizabeth Forbes, Ashley Ballard, Tao Li, Wei Zhang. IGFBP2 reprograms pancreatic cancer immune surveillance at epitranscriptome levels [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr B98.

Abstract 3391: Dissecting intratumoral cell-cell interactions in myeloid reprogramming by single cell RNA-seq

Tumor-infiltrating myeloid cells are the most abundant leukocyte population within tumors. Molecular cues from the tumor microenvironment promote the differentiation of immature myeloid cells toward an immunosuppressive phenotype. However, the in situ dynamics of the transcriptional reprogramming underlying this process are poorly understood. Therefore, we applied single cell RNA-seq (scRNAseq) to computationally investigate the cellular composition and transcriptional dynamics of tumor and adjacent normal tissues from 4 early-stage non-small cell lung cancer (NSCLC) patients. Our scRNA-seq analyses identified 11,485 cells that varied in identity and gene expression traits between normal and tumor tissues. Among these, myeloid cell populations exhibited the most diverse changes between tumor and normal tissues, consistent with tumor-mediated reprogramming. Through trajectory analysis, we identified a differentiation path from CD14+ monocytes to M2 macrophages (monocyte-to-M2). This differentiation path was reproducible across patients, accompanied by increased expression of genes (e.g. MRC1/CD206, MSR1/CD204, PPARG, TREM2) with significantly enriched functions (Oxidative phosphorylation and P53 pathway) and decreased expression of genes (e.g. CXCL2, IL1B) with significantly enriched functions (TNFa signaling via NF-kB and inflammatory response). Our analysis further identified a co-regulatory network implicating upstream transcription factors (JUN, NFKBIA) in monocyte-to-M2 differentiation, and activated ligand-receptor interactions (e.g. SFTPA1-TLR2, ICAM1-ITGAM) suggesting intratumoral mechanisms whereby epithelial cells stimulate monocyte-to-M2 differentiation. Overall, our analysis identified the prevalent monocyte-to-M2 differentiation in NSCLC, accompanied by an intricate transcriptional reprogramming mediated by specific transcriptional activators and intercellular crosstalk involving ligand-receptor interactions.

Citation Format: Qianqian Song, Gregory A. Hawkins, Leonard Wudel, Ping-Chieh Chou, Elizabeth Forbes, Ashok K. Pullikuth, Liang Liu, Guangxu Jin, Lou Craddock, Umit Topaloglu, Gregory Kucera, Stacey O’Neill, Edward A. Levine, Peiqing Sun, Kounosuke Watabe, Yong Lu, Martha A. Alexander-Miller, Boris Pasche, Lance D. Miller, Wei Zhang. Dissecting intratumoral cell-cell interactions in myeloid reprogramming by single cell RNA-seq [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3391.

Dissecting intratumoral myeloid cell plasticity by single cell RNA-seq

Tumor‐infiltrating myeloid cells are the most abundant leukocyte population within tumors. Molecular cues from the tumor microenvironment promote the differentiation of immature myeloid cells toward an immunosuppressive phenotype. However, the in situ dynamics of the transcriptional reprogramming underlying this process are poorly understood. Therefore, we applied single cell RNA‐seq (scRNA‐seq) to computationally investigate the cellular composition and transcriptional dynamics of tumor and adjacent normal tissues from 4 early‐stage non‐small cell lung cancer (NSCLC) patients. Our scRNA‐seq analyses identified 11 485 cells that varied in identity and gene expression traits between normal and tumor tissues. Among these, myeloid cell populations exhibited the most diverse changes between tumor and normal tissues, consistent with tumor‐mediated reprogramming. Through trajectory analysis, we identified a differentiation path from CD14+ monocytes to M2 macrophages (monocyte‐to‐M2). This differentiation path was reproducible across patients, accompanied by increased expression of genes (eg, MRC1/CD206, MSR1/CD204, PPARG, TREM2) with significantly enriched functions (Oxidative phosphorylation and P53 pathway) and decreased expression of genes (eg, CXCL2, IL1B) with significantly enriched functions (TNF‐α signaling via NF‐κB and inflammatory response). Our analysis further identified a co‐regulatory network implicating upstream transcription factors (JUN, NFKBIA) in monocyte‐to‐M2 differentiation, and activated ligand‐receptor interactions (eg, SFTPA1‐TLR2, ICAM1‐ITGAM) suggesting intratumoral mechanisms whereby epithelial cells stimulate monocyte‐to‐M2 differentiation. Overall, our study identified the prevalent monocyte‐to‐M2 differentiation in NSCLC, accompanied by an intricate transcriptional reprogramming mediated by specific transcriptional activators and intercellular crosstalk involving ligand‐receptor interactions.

BDA-410 Treatment Reduces Body Weight and Fat Content by Enhancing Lipolysis in Sedentary Senescent Mice

Loss of muscle mass and force with age leads to fall risk, mobility impairment, and reduced quality of life. This article shows that BDA-410, a calpain inhibitor, induced loss of body weight and fat but not lean mass or skeletal muscle proteins in a cohort of sedentary 23-month-old mice. Food and water intake and locomotor activity were not modified, whereas BDA-410 treatment decreased intramyocellular lipid and perigonadal fat, increased serum nonesterified fatty acids, and upregulated the genes mediating lipolysis and oxidation, lean phenotype, muscle contraction, muscle transcription regulation, and oxidative stress response. This finding is consistent with our recent report that lipid accumulation in skeletal myofibers is significantly correlated with slower fiber-contraction kinetics and diminished power in obese older adult mice. A proteomic analysis and immunoblot showed downregulation of the phosphatase PPP1R12B, which increases phosphorylated myosin half-life and modulates the calcium sensitivity of the contractile apparatus. This study demonstrates that BDA-410 exerts a beneficial effect on skeletal muscle contractility through new, alternative mechanisms, including enhanced lipolysis, upregulation of "lean phenotype-related genes," downregulation of the PP1R12B phosphatase, and enhanced excitation-contraction coupling. This single compound holds promise for treating age-dependent decline in muscle composition and strength.

Navigating the cascades of circumstance James A. Estes University of California Press, 2016. 291 pp

An ecologist reflects on the unexpected twists and turns that shaped his scientific career

Streptococcus pneumoniae serotype 15A in psychiatric unit, Rhode Island, USA, 2010-2011

During a pneumococcal disease outbreak in a pediatric psychiatric unit in a hospital in Rhode Island, USA, 6 (30%) of 20 patients and staff were colonized with Streptococcus pneumoniae serotype 15A, which is not included in pneumococcal vaccines. The outbreak subsided after implementation of antimicrobial drug prophylaxis and enhanced infection control measures.

Resveratrol protects neurons from cannulae implantation injury: implications for deep brain stimulation

Brain-implantable electrodes such as those used in deep brain stimulation (DBS) have a promising future in end-stage Parkinson's disease therapy. However, there is considerable injury when electrodes penetrate brain tissue. For instance, broken blood vessels and glial scar formation may impede continual DBS or electrical recording from specific neurons. To begin addressing this key safety issue, we tested the therapeutic potential of resveratrol in reducing brain trauma caused by DBS-like surgery. Microinfusion of resveratrol (10 μM) directly applied to the sub-thalamic nucleus (STN) of the rat brain significantly minimized the formation of astrocytic gliosis in response to a 27-G precision-glide cannula implant. The therapeutic effects of resveratrol extended to the "kill zone", a boundary zone of about 100 μm comprising the cannula implant and surrounding neurons. We also found that resveratrol not only provided almost complete protection from mechanical injury to the brain, but that it also prevented undesirable motor deficits often seen in animals with lesions to the STN. Lastly, continuous infusion of resveratrol over a 4-week period led to the inhibition of pro-apoptotic, neurodegenerative and cell division cycle genes that may be associated with a reduction in astrocytic gliosis and glial scar formation within the STN. Taken together, these data suggest that application of resveratrol to the brain is an effective adjunct surgical procedure for minimizing acute neuronal injury when electrodes are implanted directly into the STN.

Spiritual belief, social support, physical functioning and depression among older people in Bulgaria and Romania

OBJECTIVES

An exploratory investigation is reported into the role of spirituality and religious practice in protecting against depression among older people living in rural villages in Bulgaria and Romania, two neighbouring countries with similar cultural, political and religious histories, but with differing levels of current religiosity.

METHODS

In both countries, interviews were conducted with samples of 160 persons of 60 years and over in villages of similar socio-economic status. The Hospital Anxiety and Depression-D scale and the Royal Free Interview for Religious and Spiritual Beliefs were used to assess depression and spiritual belief and practice respectively. In addition social support, physical functioning and the presence of chronic diseases were assessed. One year later, follow-up interviews were conducted with 58 of the original sample in Bulgaria, in which additional measures of depression and of spiritual belief and practice were also included.

RESULTS

The study demonstrates, as expected, significantly lower levels of spiritual belief in the Bulgarian sample (Bulgarian mean 29.7 (SD = 19.1), Romanian mean 47.6 (SD = 11.2), t = 10.2, p < 0.001), as well as significantly higher levels of depression (Bulgarian mean 12.0 (SD = 4.9), Romanian mean 7.3 (SD = 4.1), t = 9.3, p < 0.001), the latter attributable in large part to higher morbidity and disability rates, but less evidently to differences in strength of belief. However, analyses from both the cross-sectional study and the one-year follow-up of the Bulgarian sample do suggest that spiritual belief and practice may both influence and reflect physical and mental illness.

CONCLUSIONS

Much of Eastern Europe displays high rates of depression among its older population and provides opportunities for investigation of the role of religious belief and practice in preventing and coping with depression. Further research is encouraged in populations of diverse religiosity.

Basophils are the major producers of IL-4 during primary helminth infection

IL-4 production by leukocytes is a key regulatory event that occurs early in the type 2 immune response, which induces allergic reactions and mediates expulsion of parasites. CD4(+) T cells and basophils are thought to be the key cell types that produce IL-4 during a type 2 response. In this study, we assessed the relative contribution of both CD4(+) T cell- and basophil-IL-4 production during primary and secondary responses to Nippostrongylus brasiliensis using a murine IL-4-enhanced GFP reporter system. During infection, IL-4-producing basophils were detected systemically, and tissue recruitment occurred independent of IL-4/STAT6 signaling. We observed that basophil recruitment to a tissue environment was required for their full activation. Basophil induction in response to secondary infection exhibited accelerated kinetics in comparison with primary infection. However, total basophil numbers were not enhanced, as predicted by previous models of protective immunity. Overall, the induction and migration of IL-4-producing basophils into peripheral tissues was found to be a prominent characteristic of the primary but not memory responses to N. brasiliensis infection, in which CD4(+) T cells were identified as the major source of IL-4. Whereas basophils were the major initial producers of IL-4, we determined that normal Th2 differentiation occurs independently of basophils, and depletion of basophils led to an enhancement of inflammatory cell recruitment to the site of infection.

Unilateral vocal cord paralysis associated with subdural haemorrhage in a newborn infant

A term infant developed stridor, hoarse cry and respiratory distress after forceps-assisted delivery. Oral feeding resulted in aspiration. Flexible laryngoscopy showed a right-sided vocal cord paralysis (VCP). A magnetic resonance image (MRI) of the brain revealed an ovoid lesion in the posterior fossa impinging on the brainstem, which was considered to represent a subdural haematoma. Clinical signs of vocal cord palsy and the associated MRI changes resolved spontaneously by 6 weeks of age. Vocal cord palsy is a common cause of stridor in newborn infants, although in many cases it is considered idiopathic. This is the first report of vocal cord palsy associated with subdural haemorrhage after instrumental delivery, and may represent an important and previously unappreciated cause of VCP. This case highlights the importance of magnetic resonance brain imaging in those infants with VCP in whom the aetiology is uncertain.

Differential requirements for IL-4/STAT6 signalling in CD4 T-cell fate determination and Th2-immune effector responses

Improved analytical tools have revealed that the development and expression of a Th2 immune response can be broken down into distinct stages with respect to the cytokine microenvironment that is required. Although IL-4 and its STAT6-signalling pathway are critical for the expression of Th2 effector immune responses in peripheral tissues such as the skin, lung and gut, IL-4 and STAT6 signalling are not required for the initial generation of IL-4-producing Th2 cells in the lymph node. This finding reveals that we have yet to identify the key cytokine or microenvironment that stimulates the development of this most intriguing CD4(+) T-helper subset and emphasises the tissue specificity and timing of IL-4/STAT6-dependent Th2 effector responses.

Intestinal macrophage/epithelial cell-derived CCL11/eotaxin-1 mediates eosinophil recruitment and function in pediatric ulcerative colitis

Clinical studies have demonstrated a link between the eosinophil-selective chemokines, eotaxins (eotaxin-1/CCL11 and eotaxin-2/CCL24), eosinophils, and the inflammatory bowel diseases, Crohn's disease and ulcerative colitis (UC). However, the cellular source and individual contribution of the eotaxins to colonic eosinophilic accumulation in inflammatory bowel diseases remain unclear. In this study we demonstrate, by gene array and quantitative PCR, elevated levels of eotaxin-1 mRNA in the rectosigmoid colon of pediatric UC patients. We show that elevated levels of eotaxin-1 mRNA positively correlated with rectosigmoid eosinophil numbers. Further, colonic eosinophils appeared to be degranulating, and the levels positively correlated with disease severity. Using the dextran sodium sulfate (DSS)-induced intestinal epithelial injury model, we show that DSS treatment of mice strongly induced colonic eotaxin-1 and eotaxin-2 expression and eosinophil levels. Analysis of eosinophil-deficient mice defined an effector role for eosinophils in disease pathology. DSS treatment of eotaxin-2(-/-) and eotaxin-1/2(-/-) mice demonstrated that eosinophil recruitment was dependent on eotaxin-1. In situ and immunofluorescence analysis-identified eotaxin-1 expression was restricted to intestinal F4/80(+)CD11b(+) macrophages in DSS-induced epithelial injury and to CD68(+) intestinal macrophages and the basolateral compartment of intestinal epithelial cells in pediatric UC. These data demonstrate that intestinal macrophage and epithelial cell-derived eotaxin-1 plays a critical role in the regulation of eosinophil recruitment in colonic eosinophilic disease such as pediatric UC and provides a basis for targeting the eosinophil/eotaxin-1 axis in UC.

Mechanism of interleukin-25 (IL-17E)-induced pulmonary inflammation and airways hyper-reactivity

BACKGROUND

IL-25, a novel member of the IL-17 cytokine family, promotes CD4+ T-helper 2 lymphocyte-like (Th type-2) inflammatory responses in the lung. Although IL-25 up-regulates IL-13 in the lung, the contribution of this and other type 2 cytokine signalling pathways to the induction and persistence of airways hyper-reactivity (AHR) and allergic inflammation are unclear.

OBJECTIVE

To determine the downstream factors employed by IL-25 to induce Th type-2 pulmonary inflammation and AHR.

METHODS

IL-25 was delivered to the airways of BALB/c mice by intra-tracheal (i.t.) instillation and AHR and Th type-2 inflammatory responses were characterized in wild type (WT) and Th type-2-cytokine and -signalling pathway-deficient (-/-) mice.

RESULTS

IL-25 treatment resulted in AHR, eosinophilic inflammation, mucus hypersecretion and a progressive increase in the production of Th type-2 cytokines in the lungs. Levels of arginase-I (arg-I) and eotaxin were also elevated by IL-25 treatment. A significant reduction in AHR, and attenuation of mucus production was observed in IL-25-treated IL-13-/-, IL-4 receptor alpha (IL-4Ralpha-/-)- and signal-transducer-and-activator-of-transcription-factor-6 (STAT6-/-)-deficient mice. AHR was also inhibited in IL-4(-/-)- and IL-5/eotaxin(1)(-/-)- deficient mice treated with IL-25, however, mucus hypersecretion was not completely ablated. IL-25 promoted Th type-2 responses by directly acting on naïve T cells.

CONCLUSION

IL-25 potently (single dose) induces sustained AHR and acute pulmonary inflammation with eosinophilia. IL-25-induced AHR is dependent on the production of Th type-2 cytokines, and removal of IL-13 and its signal transduction pathway prevents IL-25-induced airways inflammation and AHR. IL-25 potently induces inflammatory cascades that may exacerbate allergic airways inflammation by promoting Th type-2 cytokine responses in conjunction with the up-regulation of factors (eotaxin and arg-I) that can amplify inflammation associated with allergic disorders. Dysregulation in IL-25 production may predispose to features of allergic airways disease.

Mechanistic analysis of experimental food allergen-induced cutaneous reactions

Individuals with food allergy often present with uritcaria and atopic dermatitis. Indeed, susceptibility to food allergy may predispose to the development of these cutaneous allergic disorders. Recently, we developed a model of food allergy, whereby oral consumption of food [pea Pisum sativum L.; expressing alpha-amylase inhibitor-1 (alphaAI) from the common bean Phaseolus vulgaris L. cv Tendergreen (pea-alphaAI)] promotes a T helper cell type 2 (Th2) inflammatory response and predisposes to cutaneous allergic reactions following subsequent food allergen (alphaAI) exposure. To delineate the kinetics of food allergen-induced cutaneous reactions and examine the inflammatory mechanisms involved in this allergic reaction, we used interleukin (IL)-13-, IL-4 receptor alpha-, and eotaxin-1-deficient mice and performed serum transfer and CD4+ T cell depletion studies. We demonstrate that consumption of pea-alphaAI promotes an alphaAI-specific immunoglobulin G1 (IgG1) and IgE antibody response. Furthermore, we show that subsequent food allergen (alphaAI) challenge in the skin induced an early (3 h)- and late-phase (24 h) cutaneous allergic reaction. The early-phase response was associated with mast cell degranulation and the presence of Ig, whereas the late-phase response was characterized by a lymphoid and eosinophilic infiltrate, which was critically regulated by CD4+ T cells, IL-13, and eotaxin-1. Collectively, these studies demonstrate that food allergy can predispose to cutaneous inflammatory reactions, and these processes are critically regulated by Th2 immune factors.

ICAM-1-dependent pathways regulate colonic eosinophilic inflammation

Eosinophilic inflammation is a common feature of numerous eosinophil-associated gastrointestinal (EGID) diseases. Central to eosinophil migration into the gastrointestinal tract are the integrin-mediated interactions with adhesion molecules. Although the mechanisms regulating eosinophil homing into the small intestine have begun to be elucidated, the adhesion pathways responsible for eosinophil trafficking into the large intestine are unknown. We investigated the role of adhesion pathways in eosinophil recruitment into the large intestine during homeostasis and disease. First, using a hapten-induced colonic injury model, we demonstrate that in contrast to the small intestine, eosinophil recruitment into the colon is regulated by a beta7 -integrin addressin cell adhesion molecule-1-independent pathway. Characterization of integrin expression on colonic eosinophils by flow cytometry analysis revealed that colonic CC chemokine receptor 3+ eosinophils express the intercellular adhesion molecule-1 (ICAM-1) counter-receptor integrins alphaL, alphaM, and beta2. Using ICAM-1-deficient mice and anti-ICAM-1 neutralizing antibodies, we show that hapten-induced colonic eosinophilic inflammation is critically dependent on ICAM-1. These studies demonstrate that beta2 -integrin/ICAM-1-dependent pathways are integral to eosinophil recruitment into the colon during GI inflammation associated with colonic injury.

Safety and immunogenicity of an oral, inactivated, whole-cell vaccine for Shigella sonnei: preclinical studies and a Phase I trial

Orally delivered, inactivated whole-cell vaccines are safe methods of inducing local and systemic immunity. To increase surface proteins associated with adherence and invasion, Shigella sonnei were grown in BHI broth containing deoxycholate. A whole-cell vaccine (SsWC) was then produced by formalin inactivation. In pre-clinical studies, the SsWC vaccine was immunogenic and protected against S. sonnei-induced keratoconjunctivitis in the guinea pig model. In a randomized, double-blind, placebo-controlled, Phase I study, 10 evaluable subjects received either three doses of SsWC on Days 0, 14, and 28 (N = 3); five doses of SsWC on Days 0, 2, 4, 6, and 28 (N = 4); or placebo (N = 3). Each dose contained 2.0 x 10(10) inactivated cells. Serum and fecal antibodies against SsWC, LPS, and IpaC were measured by ELISA. A > or = 4-fold increase in titer was considered significant. Both SsWC dosing regimens were well tolerated. No fever or severe gastrointestinal symptoms were noted by any of the vaccinated subjects. Antibody responses were similar in the two dosing groups. Serum IgG or IgA responses to SsWC were seen in six of seven vaccinees (86%), to LPS in four of seven (57%), and to IpaC in five of seven (61%). Fecal IgA responses to these three antigens developed in five of five, three of five, and three of five subjects, respectively. Among the seven vaccinees, geometric mean rises in serum IgA levels to all three immunogens were significant; IgG increases trended toward significance (paired one-tailed t-test). We conclude that SsWC was immunogenic and protective in animal studies and well tolerated and immunogenic in a Phase I trial.

Immunopathogenesis of experimental ulcerative colitis is mediated by eosinophil peroxidase

The precise role that individual inflammatory cells and mediators play in the development of gastrointestinal (GI) dysfunction and extraintestinal clinical manifestations of ulcerative colitis (UC) is unknown. In this study, we have used a mouse model of UC to establish a central role for eotaxin and, in turn, eosinophils in the development of the immunopathogenesis of this disease. In this model the administration of dextran sodium sulfate (DSS) induces a prominent colonic eosinophilic inflammation and GI dysfunction (diarrhea with blood and shortening of the colon) that resembles UC in patients. GI dysfunction was associated with evidence of eosinophilic cytolytic degranulation and the release of eosinophil peroxidase (EPO) into the colon lumen. By using IL-5 or eotaxin-deficient mice, we show an important role for eotaxin in eosinophil recruitment into the colon during experimental UC. Furthermore, using EPO-deficient mice and an EPO inhibitor resorcinol we demonstrate that eosinophil-derived peroxidase is critical in the development of GI dysfunction in experimental UC. These findings provide direct evidence of a central role for eosinophils and EPO in GI dysfunction and potentially the immunopathogenesis of UC.

T helper-2 immunity regulates bronchial hyperresponsiveness in eosinophil-associated gastrointestinal disease in mice

BACKGROUND & AIMS

Eosinophil-associated gastrointestinal diseases are frequently associated with extraintestinal features, including bronchopulmonary manifestations. The factors predisposing to bronchial hyperresponsiveness in eosinophil-associated gastrointestinal diseases are unknown. To elucidate the mechanistic link between eosinophil-associated gastrointestinal diseases and bronchial hyperresponsiveness, we used murine models of eosinophil-associated gastrointestinal diseases and eotaxin-1/transgene-induced eosinophil-associated gastrointestinal diseases.

METHODS

Mice were sensitized and orally challenged with ovalbumin-coated encapsulated particles to induce eosinophil-associated gastrointestinal disease, and bronchial responsiveness was examined. Furthermore, transgenic mice expressing eotaxin in the intestine (with the rat fatty acid-binding promoter) were used to specifically elucidate the contribution of this chemokine in eosinophil-associated gastrointestinal disease-associated bronchial hyperresponsiveness.

RESULTS

The induction of allergen-induced eosinophil-associated gastrointestinal disease was directly correlated with the development of bronchial hyperresponsiveness. The development of bronchial hyperresponsiveness in mice with allergen-induced eosinophil-associated gastrointestinal disease was dependent on eotaxin expression in the gastrointestinal tract. Expression of eotaxin in the gastrointestinal tract of transgenic mice was sufficient to promote bronchial hyperresponsiveness. Bronchial hyperresponsiveness was shown to be directly linked to the aberrant CD4(+) T helper 2 lymphocyte production of interleukin-13. It is interesting to note that transgenic expression of eotaxin was linked with enhanced T helper 2 lymphocyte/cytokine synthesis (interleukin-4, -5, and -13) and the production of mucosal immunoglobulin G1 in the gastrointestinal lumen. We also showed that eotaxin treatment of CD4(+) T cells enhanced interleukin-13 production in vitro.

CONCLUSIONS

These studies suggest that increased expression of eotaxin in the gastrointestinal compartment can lead to increased CD4(+) T cell-derived T helper 2 lymphocyte-cytokine production that drives aberrant immunophysiological responses in distant noninflamed mucosal tissue (the lung). These results provide a possible explanation for the altered lung function seen in some patients with inflammatory gastrointestinal disorders.

Chemokines in eosinophil-associated gastrointestinal disorders

Eosinophil-associated gastrointestinal disorders (EGDs) are characterized by a pronounced cellular inflammation. Recent clinical and experimental investigations have implicated a family of molecules known as chemokines in the regulation of leukocyte recruitment in these diseases. The underlying cellular and molecular mechanisms involved in chemokine-mediated cellular infiltration are largely unknown. In this review, we describe the role of CD4+ T cells and eosinophils in the clinical manifestations of EGDs and discuss the current understanding of the role of chemokines in the recruitment of these cells in the expression of diseases.

The acetylcholinesterase gene and organophosphorus resistance in the Australian sheep blowfly, Lucilia cuprina

Acetylcholinesterase (AChE), encoded by the Ace gene, is the primary target of organophosphorous (OP) and carbamate insecticides. Ace mutations have been identified in OP resistants strains of Drosophila melanogaster. However, in the Australian sheep blowfly, Lucilia cuprina, resistance in field and laboratory generated strains is determined by point mutations in the Rop-1 gene, which encodes a carboxylesterase, E3. To investigate the apparent bias for the Rop-1/E3 mechanism in the evolution of OP resistance in L. cuprina, we have cloned the Ace gene from this species and characterized its product. Southern hybridization indicates the existence of a single Ace gene in L. cuprina. The amino acid sequence of L. cuprina AChE shares 85.3% identity with D. melanogaster and 92.4% with Musca domestica AChE. Five point mutations in Ace associated with reduced sensitivity to OP insecticides have been previously detected in resistant strains of D. melanogaster. These residues are identical in susceptible strains of D. melanogaster and L. cuprina, although different codons are used. Each of the amino acid substitutions that confer OP resistance in D. melanogaster could also occur in L. cuprina by a single non-synonymous substitution. These data suggest that the resistance mechanism used in L. cuprina is determined by factors other than codon bias. The same point mutations, singly and in combination, were introduced into the Ace gene of L. cuprina by site-directed mutagenesis and the resulting AChE enzymes expressed using a baculovirus system to characterise their kinetic properties and interactions with OP insecticides. The K(m) of wild type AChE for acetylthiocholine (ASCh) is 23.13 microM and the point mutations change the affinity to the substrate. The turnover number of Lucilia AChE for ASCh was estimated to be 1.27x10(3) min(-1), similar to Drosophila or housefly AChE. The single amino acid replacements reduce the affinities of the AChE for OPs and give up to 8.7-fold OP insensitivity, while combined mutations give up to 35-fold insensitivity. However, other published studies indicate these same mutations yield higher levels of OP insensitivity in D. melanogaster and A. aegypti. The inhibition data indicate that the wild type form of AChE of L. cuprina is 12.4-fold less sensitive to OP inhibition than the susceptible form of E3, suggesting that the carboxylesterases may have a role in the protection of AChE via a sequestration mechanism. This provides a possible explanation for the bias towards the evolution of resistance via the Rop-1/E3 mechanism in L. cuprina.

Singlet oxygen and superoxide characteristics of a series of novel asymmetric photosensitizers

The singlet oxygen quantum yields and superoxide quantum yields for a series of novel compounds based on an asymmetrical protoporphyrin molecule have been examined. Electron spin resonance was used to measure superoxide yield and time resolved luminescence for singlet oxygen. A comparison between these results and previously published cell survival data was carried out. A broad association was found between singlet oxygen quantum yield and clonogenic cell kill.

Novel asymmetric photosensitizers: an in vitro study

A series of compounds based on an asymmetrical protoporphyrin molecule have been examined. The paired groups of sensitizers differed in terms of the presence or absence of a permanent positive charge, in the alkyl side chain length and in having either a primary or secondary amine substituent. The effects of these variables on drug uptake, partition coefficient and photodynamic cell kill were tested. Drug uptake and partition coefficient were shown to be correlated. Differences in gross uptake were found within paired groups of sensitizers although cell-associated uptake alone did not correlate with clonogenic cell survival. Of the compounds tested it was the sensitizers with alkyl side chains, rather than the permanently positively charged compounds, which resulted in the greatest degree of clonogenic cell kill.

Pilot project on functional outcome in stroke

The purpose of this pilot project was to compare the outcome of stroke survivors cared for on an Acute Stroke Unit (ASU) to those who received care on a routine medical-surgical unit. The sample included a total of 88 patients, 68 admitted to an acute stroke unit and 20 admitted to a medical-surgical unit. The Functional Index Measure was used to assess in-hospital functional gains in the two groups. There appeared to be a trend toward increased functional gains in the group of stroke patients cared for on the Acute Strike Unit as compared to the group of patients cared for on medical-surgical units. These findings provide a foundation for neuroscience nurses and other health care professionals to study functional gains after stroke.

Improving information for nuclear medicine department outpatients

In two large inner city hospitals we have conducted a survey of the letters sent to patients before their attendance at a nuclear medicine department. The majority of questions asked for a graded answer (poor, fair, ok, good, excellent). Patients were handed the survey form when they had completed their test and the survey was continued until 100 valid replies had been received at each hospital. Information leaflets, as recommended by the British Nuclear Medicine Society (BNMS), were subsequently issued to all patients and at one hospital the patient information letters were rewritten. The surveys were then repeated. There was a significant (P < 0.001) improvement in patient satisfaction with the information provided. In some areas, for example, instructions about getting to the hospital, no different information was provided and there was no change between the surveys, as would be expected. Curiously, questions allowing free text answers were more often completed by patients from Dudley Road Hospital, Birmingham, than from Guy's Hospital, London. Some possible explanations for this difference are discussed. Particularly reassuring was that more women understood about precautions regarding pregnancy or breastfeeding as a result of the leaflets. We would recommend the advice of the BNMS to other nuclear medicine departments.

The uptake of porphyrin and zinc-metalloporphyrin by the primate prostate

The relative distribution of sensitizer drugs in the prostate and its contiguous organs is of importance in the treatment of localized prostatic cancer with photodynamic therapy. Using the primate model, whose prostate is both morphologically and physiologically homologous with its human counterpart, the distribution of hematoporphyrin derivative (HpD) amongst organs of urological interest was determined. Hematoporphyrin derivative levels were comparatively low in both caudal and cranial prostatic lobes (0.93-1.77 micrograms/g) and were similar to those in rectum, urethra and the skin. The reticuloendothelial organs, liver, spleen and also the kidney accumulated the highest quantities of porphyrin (4.76-9.8 micrograms/g, liver > spleen > kidney). Despite a high avidity of prostatic tissue for zinc, a zinc-metalloporphyrin (Zn-HpD) did not concentrate selectively in the prostate. The results are of clinical value in view of the homology between the primate and the human.

Nitrogen analogues of haematoporphyrin and haematoporphyrin derivative

The preparation of a number of amines related to haematoporphyrin (HP) and haematoporphyrin derivative (HPD) have been studied and their composition and structure discussed through examination of their 1H, 13C NMR and mass spectral data and other physical properties. In vitro biological studies have been carried out and have shown these amines to have a similar photodynamic efficiency to that of HPD. One of these showed cytotoxic properties at exceptionally low light energy levels.

Mechanism of action of beta-glycerophosphate on bone cell mineralization

Experiments were performed to determine whether beta-glycerophosphate (beta-GP) promoted mineralization in vitro by modulating bone cell metabolic activity and/or serving as a local source of inorganic phosphate ions (Pi). Using MC3T3-E1, ROS 17/2.8, and chick osteoblast-like cells in the presence of beta-GP or Pi, we examined mineral formation, lactate generation, alkaline phosphatase (AP) activity, and protein and phospholipid synthesis. Neither beta-GP nor Pi modulated any of the major biosynthetic activities of the bone cells. Thus, we found no change in the levels of phospholipids, and the total protein concentration remained constant. Measurement of lactate synthesis showed that beta-GP did not effect the rate of anaerobic glycolysis. Evaluation of medium Pi levels clearly indicated that beta-GP was hydrolyzed by bone cells; within 24 hours, almost 80% of 10 mM beta-GP was hydrolyzed. It is likely that this local increase in medium Pi concentration promoted rapid mineral deposition. Chemical, energy dispersive X-ray, and Fourier transform infrared analysis of the mineral formed in the presence of beta-GP showed that it was nonapatitic; moreover, mineral particles were also seen in the culture medium itself. Experiments performed with a cell-free system indicated that mineral particles formed spontaneously in the presence of AP and beta-GP and were deposited into a collagen matrix. We conclude that medium supplementation with beta-GP or Pi should not exceed 2 mM. If this value is exceeded, then there will be nonphysiological mineral deposition in the bone cell culture.

Ascorbic acid regulates multiple metabolic activities of cartilage cells

Bones grow in length because of the activities of cartilage cells in the epiphyseal growth plate. We have examined selected events that occur in the growth cartilage by the use of cultured epiphyseal cells; we have also evaluated the influence of ascorbate on these activities. Our studies indicate that 1) ascorbate induces the expression of a unique collagen isoform, type X collagen; 2) ascorbate stimulates alkaline phosphatase activity of maturing chondrocytes; and 3) ascorbate regulates the energy status of the maturing chondrocyte. We have found that in the presence of ascorbate there is a change in oxidative activity. Thus, lactate formation is inhibited, there is an increase in the adenylate energy charge ratio, and there is an elevation in the activity of isocitrate dehydrogenase. The results of these studies point to multiple effects of vitamin C on chondrocyte maturation involving changes in protein synthesis and energy metabolism.

The Tc3 family of transposable genetic elements in Caenorhabditis elegans

We describe genetic and molecular properties of Tc3, a family of transposable elements in Caenorhabditis elegans. About 15 Tc3 elements are present in the genomes of several different wild-type varieties of C. elegans, but Tc3 transposition and excision are not detected in these strains. Tc3 transposition and excision occur at high frequencies, however, in strain TR679, a mutant identified because of its highly active Tc1 elements. In TR679, Tc3 is responsible for several spontaneous mutations affecting the unc-22 gene. Tc3-induced mutations are unstable, and revertants result from precise or nearly precise excision of Tc3. Although Tc3 is very active in TR679, it is not detectably active in several other mutator mutants, all of which exhibit high levels of Tc1 activity. Tc3 is 2.5 kilobases long, and except for sequences near its inverted repeat termini, it is unrelated to Tc1. The termini of Tc3 are inverted repeats of at least 70 base pairs; the terminal 8 nucleotides of Tc3 are identical to 8 of the terminal 9 nucleotides of Tc1.

Systems therapy in a day-treatment setting

This is a paper about doing systems therapy in a day-treatment facility for children identified as severely emotionally disturbed. Children's emotional problems are seen and treated as aspects of family and larger-system problems. An intervention process has been articulated. Information management is a central team task. All staff are team members. While many theories and therapies inform the intervention process, there is no attempt to integrate approaches. Rather, a consultation process serves as a clearinghouse for information management. The managers of the information process think in systems terms and that thinking is "meta" to other positions. In this paper the thinking, the organization of the workplace, and some of the processes which people experience are explored.

3-amino-triazole effects on the eye of young and adult rabbits in the presence and absence of hydrogen peroxide

3-aminotriazole (3AT) is known to reduce catalase levels in ocular tissues when given intravenously or orally. Rabbits were given either 4 ml/kg of a 3M solution of 3AT intravenously or a 2% solution as drinking fluid. Intravenous 3AT administration was followed at 4 hrs by an intracameral injection of hydrogen peroxide (H2O2) to give an aqueous humor concentration of 3.2 mM in young (4-6 weeks of age) and a 3.3 mM in adult (6 months of age) rabbits. Tissues were taken for microscopy at either 6 or 24 hours after intracameral H2O2. Neither oral nor intravenous 3AT alone in adult rabbits, or intravenous 3AT in young rabbits, had any effect on either iris, ciliary process, or corneal endothelial morphology. After oral 3AT in adult rabbits, H2O2 caused highly edematous ciliary processes with dilated vessels; corneal endothelial cells were swollen. Previous studies in adult and young rabbits have shown that intracameral H2O2 alone caused few morphological changes in young, but marked changes in the adult that correlated with the 35 to 50% lower catalase levels found in iris and corneal endothelium, respectively, in adult ocular tissues. Young rabbits pre-treated with intravenous 3AT, when examined at 6 and 24 hours after intracameral H2O2, showed swollen ciliary processes, vessel dilation, alteration of the pigment epithelium and corneal endothelial damage. In non 3AT-treated young rabbits, H2O2 caused only minor morphological changes. In adult animals at 6 and 24 hours after intracameral H2O2 the ciliary processes were edematous in the absence of 3AT; after intravenous 3AT and intracameral H2O2 the changes were even more marked, with very severe swelling of ciliary processes and corneal endothelial damage. It is apparent that the decrease in catalase caused by 3AT allows H2O2 to induce damage even in young animals where it usually does not induce morphological changes. In adult animals, the effects of H2O2 are enhanced in the presence of 3AT.

Ammonium regulation in Aspergillus nidulans

l-Glutamate uptake, thiourea uptake, and methylammonium uptake and the intracellular ammonium concentration were measured in wild-type and mutant cells of Aspergillus nidulans held in various concentrations of ammonium and urea. The levels of l-glutamate uptake, thiourea uptake, nitrate reductase, and hypoxanthine dehydrogenase activity are determined by the extracellular ammonium concentration. The level of methylammonium uptake is determined by the intracellular ammonium concentration. The uptake and enzyme characteristics of the ammonium-derepressed mutants, meaA8, meaB6, DER3, amrA1, xprD1, and gdhA1, are described. The gdhA mutants lack normal nicotinamide adenine dinucleotide phosphate-glutamate dehydrogenase (NADP-GDH) activity and are derepressed with respect to both external and internal ammonium. The other mutant classes are derepressed only with respect to external ammonium. The mutants meaA8, DER3, amrA1, and xprD1 have low levels of one or more of the l-glutamate, thiourea, and methylammonium uptake systems. A model for ammonium regulation in A. nidulans is put forward which suggests: (i) NADP-GDH located in the cell membrane complexes with extracellular ammonium. This first regulatory complex determines the level of l-glutamate uptake, thiourea uptake, nitrate reductase, and xanthine dehydrogenase by repression or inhibition, or both. (ii) NADP-GDH also complexes with intracellular ammonium. This second and different form of regulatory complex determines the level of methylammonium uptake by repression or inhibition, or both.

Relation of brain sensitivity and hepatic metabolism of hexobarbitone to dose-response relations in infant and young rats

The dose-response relation to hexobarbitone of infant (5 day) and young (44 day) male rats was examined, and the relative contribution of hepatic metabolism (measured in vitro) and changes in brain sensitivity to the overall response were evaluated. The infant rat shows a parallel shift to the left in its dose-response curve with the relative potency of hexobarbitone almost 5 times greater than for the 44 day old animal. The slope of the curves show marked changes at the first lethal dose level of drug. This and other evidence suggest that death may not be merely an extension of the mechanism causing hypnosis. Infant rats exhibited a shorter increment in sleep time for increasing doses of hexobarbitone than is predictable from their low rate of in vitro metabolism. Although this is also true for the young rats, the two values are in much closer agreement than for the infant animals. Brain concentrations of hexobarbitone, measured upon regaining of the righting reflex, were lower in the infant than in the young rat. This suggests the central nervous system of the infant rat has an increased sensitivity to the drug.