Inhaled Nitric Oxide Treatment for Aneurysmal SAH Patients With Delayed Cerebral Ischemia

Background

We demonstrated experimentally that inhaled nitric oxide (iNO) dilates hypoperfused arterioles, increases tissue perfusion, and improves neurological outcome following subarachnoid hemorrhage (SAH) in mice. We performed a prospective pilot study to evaluate iNO in patients with delayed cerebral ischemia after SAH.

Methods

SAH patients with delayed cerebral ischemia and hypoperfusion despite conservative treatment were included. iNO was administered at a maximum dose of 40 ppm. The response to iNO was considered positive if: cerebral artery diameter increased by 10% in digital subtraction angiography (DSA), or tissue oxygen partial pressure (PtiO₂) increased by > 5 mmHg, or transcranial doppler (TCD) values decreased more than 30 cm/sec, or mean transit time (MTT) decreased below 6.5 secs in CT perfusion (CTP). Patient outcome was assessed at 6 months with the modified Rankin Scale (mRS).

Results

Seven patients were enrolled between February 2013 and September 2016. Median duration of iNO administration was 23 h. The primary endpoint was reached in all patients (five out of 17 DSA examinations, 19 out of 29 PtiO₂ time points, nine out of 26 TCD examinations, three out of five CTP examinations). No adverse events necessitating the cessation of iNO were observed. At 6 months, three patients presented with a mRS score of 0, one patient each with an mRS score of 2 and 3, and two patients had died.

Conclusion

Administration of iNO in SAH patients is safe. These results call for a larger prospective evaluation.

Interference of angiotensin II and enalapril with hepatic blood flow regulation

Acute reduction of portal vein blood flow (Qpv) increases hepatic arterial perfusion (Qha) [the hepatic arterial buffer response (HABR)]. Angiotensin II (AT-II) reduces Qpv, but its effect on HABR is not known. We explored interactions of AT-II and enalapril with hepatic blood flow regulation. Twenty healthy anesthetized pigs were randomized to receive AT-II (n = 8) from 5 to 61 ng/kg per min, enalapril (n = 8) from 3 to 24 μg/kg per h, or saline (n = 4). HABR was assessed by occluding portal vein and expressed as 1) ratio between changes in Qha and Qpv, 2) hepatic arterial conductance (Cha). AT-II infusion increased mean arterial blood pressure from 74 (66-77) mmHg to 116 (109-130) mmHg (median, IQR; P < 0.0001) and decreased cardiac output, Qpv, and renal artery flow (-24%, -28% and -45%, respectively). The fraction of cardiac output of Qha, carotid, and femoral flows increased. With enalapril, blood pressure decreased, whereas cardiac output was maintained with flow redistribution favoring hepatic and renal arteries. In AT-II group, dQha/dQpv increased from 0.06 (0.03, 0.17) to 0.24 (0.13, 0.31) (P = 0.002), but Cha during acute portal vein occlusion decreased from 4.3 (1.6, 6.6) to 2.9 (1.2, 3.7) ml/mmHg (P = 0.003). Both variables remained unchanged in the enalapril group and in controls. AT-II infusion reduces portal flow in parallel with cardiac output and induces a dose-dependent redistribution of flow, favoring brain, hepatic artery, and peripheral tissues at the expense of renal perfusion. During HABR, AT-II decreases Cha but increases Qha compensation, likely as result of increased hepatic arterial perfusion pressure. Enalapril had no effect on HABR.

Galectin-7: will the lectin's activity establish clinical correlations in head and neck squamous cell and basal cell carcinomas?

The human lectin galectin-7 (Gal-7; p53-induced gene-1) has anti- and pro-malignant features in different in vitro models. We tried to clarify relation of its expression to cellular and clinical parameters in head and neck squamous and basal cell carcinomas. Using a non-cross-reactive antibody, immunohistochemical staining in squamous cell epithelia (epidermis, epithelium of oropharynx and larynx) (n = 57), squamous cell carcinomas (n = 47) and lymph node metastases (n = 25), as well as basal cell carcinomas (n = 10) were studied. This monitoring was flanked by processing to assess the level of differentiation (cytokeratins 10 and 14), proliferation (Ki67) and basal lamina formation (collagen IV). The results were correlated with clinical and pathological findings (grading, TNM-staging, extracapsular spread, angio- and lymphangioinvasion, perineural invasion, recurrence and survival). Gal-7 resides in all layers of epithelia with cytoplasmic and nuclear localization in normal specimens. Basal cell carcinomas were devoid of the Gal-7 respective signal. Squamous cell carcinomas were positive, presenting different staining profiles. Intense staining was predominantly found in squamous cell cancers with high degrees of differentiation and keratinization. Fittingly, poor level of differentiation (P = 0.0009), absence of keratinization (P = 0.0105) and significant discontinuity or absence of collagen IV expression in the peritumoral basal lamina (P = 0.0024) was found in Gal-7-negative tumors. Gal-7 presence was not related to gender, primary tumor site, T-stage, N-stage, clinical stage, extracapsular spread, angio- and lymphangioinvasion, perineural spread or treatment outcome at a statistically significant level. Immunohistochemical analysis revealed a positive correlation for differentiation and keratinization to Gal-7 presence in squamous cell carcinomas. Absence of Gal-7 expression was detected in basal cell carcinomas. These clinical data delineate Gal-7 influence on differentiation in vivo, without evidence for a role in dissemination reported for lymphoma.

Immunohistochemical fingerprinting of the network of seven adhesion/growth-regulatory lectins in human skin and detection of distinct tumour-associated alterations

Glycans of natural glycoconjugates are considered as a source of biological information relevant to cell adhesion or growth. Sugar-based messages are decoded and translated into responses by endogenous lectins. This mechanism assigns a functional dimension to tumour-associated changes of glycosylation. Consequently, it calls for mapping the lectin presence in tumours. Such an analysis has so far commonly been performed with the scope to determine expression of a few distinct proteins, e.g. from the effector family of galectins with focus on galectins-1 and -3. Due to the emerging evidence for functional divergence among galectins it is timely to address the challenge to evaluate their presence beyond these few family members. Having raised a panel of non-cross- -reactive antibodies against seven human galectins covering all three subfamilies, we de scribe their expression profiles in human skin. Comparison of normal and malignant tissues enabled us to define galectin-type-dependent alterations, arguing in favour of distinct functionalities. It is concluded that comprehensive monitoring performed to define the different aspects of the galectin network, as documented in this pilot study, is advisable for future histopathologic studies aimed at delineating clinical correlations.

Human galectin-2: nuclear presence in vitro and its modulation by quiescence/stress factors

Galectins have the particular capacity to interact with distinct proteins, in addition to the typical reactivity of lectins with glycans. Therefore, they can be functionally active when residing at places other than the membrane or extracellular matrix. In fact, nuclear presence of galectins-1 and -3 is solidly documented but it is an open question whether these two cases are exceptional within this lectin family. Thus, galectin-2, which shares 43% sequence identity on the protein level with galectin-1, warrants study in this respect. Based on initial immunohistochemical evidence we herein address the issue as to whether this galectin can join the category of nuclear lectins. To do so we studied different types of cell in vitro using an antibody preparation free of cross-reactivity against other tested galectins. The immunocytochemical experiments revealed that galectin-2 was present in nuclei of murine 3T3 fibroblasts and also genetically engineered human colon carcinoma cells with stable ectopic expression. Transport of galectin-2 to the nucleus could be enhanced by physical (UV light), chemical (mitomycin C, serum withdrawal) or cell biological (coculture with stromal cells) treatment modalities. As a means of further characterizing the staining profile cytochemically, a series of markers with well-defined site of residency within the nuclear compartment was tested in parallel. Importantly, no colocalization with galectins-1 and -3 and the splicing factor SC35 was detectable, the former cases also serving as inherent specificity control. In contrast, a similarity was uncovered in the case of the promyelocytic leukemia (PML) protein as marker of PML nuclear bodies. In aggregate, nuclear localization is documented for galectin-2. This attribute should thus not be considered as an exceptional finding confined to galectins-1 and -3. That even closely related family members, here galectins-1 and -2, exhibit distinct intranuclear localization patterns gives ensuing research a clear direction.

Gene-expression signature of adhesion/growth-regulatory tissue lectins (galectins) in transitional cell cancer and its prognostic relevance

AIMS

Lectins, and especially galectins, appear to be important in malignancy-associated processes. The aim was to analyse comprehensively the presence of galectins in urothelial tumours.

METHODS AND RESULTS

Non-cross-reactive antibodies against seven family members from the three subgroups (prototype: galectin-1, -2 and -7; chimera type: galectin-3; tandem-repeat type: galectin-4, -8 and -9) were used. Gene expression was monitored in specimens of normal urothelium, fresh tumour tissue and cell lines by real-time polymerase chain reaction (PCR). The presence and evidence of tumour-associated up-regulation were shown for galectin-1 and -3. This was less clear-cut for galectin-4 and -8. Galectin-7 was expressed in all cell lines; galectin-2 and -9 were detected at comparatively low levels. Galectin-2, -3 and -8 up-regulation was observed in superficial tumours, but not in muscle-invasive tumours (P < 0.05). Immunoreactivity correlated with tumour grading for galectin-1, -2 and -8, and disease-dependent mortality correlated with galectin-2 and -8 expression. Binding sites were visualized using labelled galectins.

CONCLUSIONS

The results demonstrate a complex expression pattern of the galectin network in urothelial carcinomas. Galectin-1, -2, -3 and -8 are both potential disease markers and also possible targets for bladder cancer therapy.

Murine homodimeric adhesion/growth-regulatory galectins-1, -2 and -7: comparative profiling of gene/ promoter sequences by database mining, of expression by RT-PCR/immunohistochemistry and of contact sites for carbohydrate ligands by computational chemistry

Following the detection of individual members of the family of galectins it is an obvious challenge to define the extent of functional overlap/divergence among these proteins. As a step to address this issue a comparative profiling has been started in the mouse as a model organism, combining sequence analysis, expression patterns and structural features in the cases of the homodimeric galectins-1, -2 and -7. Close relationship was apparent at the level of global gene organization. Scrutiny of the proximal promoter regions for putative transcription-factor-binding sites by two search algorithms uncovered qualitative and quantitative differences with potential to influence the combinatorial functionality of regulatory sequences. RT-PCR mapping with samples from an array of 17 organs revealed significant differences, separating rather ubiquitous gene expression of galectin-1 from the more restricted individual patterns of galectins-2 and -7. Using specific antisera obtained by affinity depletion including stringent controls to ascertain lack of cross-reactivity these results were corroborated at the level of galectin localization in fixed tissue sections. Nuclear presence was seen in the case of galectin-1. In addition to nonidentical expression profiles the mapping of the carbohydrate recognition domains of galectins-1 and -7 by homology modelling and docking of naturally occurring complex tetra- and pentasaccharides disclosed a series of sequence deviations which may underlie disparate affinities for cell surface glycans/glycomimetic peptides. In view of applicability the presented data can serve as useful reference to delineate changes with respect to disease and in genetically engineered models. To enable more general conclusions on the galectin network it is warranted to further pursue this combined approach within this lectin family.

Human galectin-2: expression profiling by RT-PCR/immunohistochemistry and its introduction as a histochemical tool for ligand localization

Sugar-encoded information of glyco-conjugates is translated into cellular responses by endogenous lectins. Galectins stand out against other lectin families due to their wide range of functions including cell adhesion, tissue invasion or growth regulation exerted at extracellular, membrane, cytoplasmic and nuclear sites. This remarkable versatility warrants close scrutiny of their emerging network, in this study with focus on homodimeric human galectin-2. We first detected presence of specific mRNA in various tissue types by processing post mortem and surgical specimens by RT-PCR protocols. Overlap of gene expression was noted with proto-type galectins-1 and -7 and also family members from the other two subgroups. To monitor expression on the level of protein a polyclonal anti-galectin-2 antibody was raised. Immunopositivity was semi-quantitatively assessed in sections of 209 human samples establishing an array both of normal tissues and samples with inflammation or benign/malignant growth. In general, positivity was predominantly epithelial without restriction of staining to certain tissue types, as fittingly indicated by our RT-PCR analysis. Staining was not limited to the cytoplasm but also included nuclear sites. To examine the suitability of the labeled lectin as a histochemical probe we biotinylated galectin-2 under activity-preserving conditions and introduced it to tissue profiling. Specific cytoplasmic staining proved the validity of the concept. Our results encourage systematic histopathologic studies by immuno- and lectin histochemistry, especially by adding galectin-2 as study object to galectin fingerprinting which has already yielded prognostic information on galectins-1, -3, -4 and -8 and hereby contributed to define functional overlap/divergence in this lectin family.

Identification and characterization of SppA, a novel light-inducible chloroplast protease complex associated with thylakoid membranes

A new component of the chloroplast proteolytic machinery from Arabidopsis thaliana was identified as a SppA-type protease. The sequence of the mature protein, deduced from a full-length cDNA, displays 22% identity to the serine-type protease IV (SppA) from Escherichia coli and 27% identity to Synechocystis SppA1 (sll1703) but lacks the putative transmembrane spanning segments predicted from the E. coli sequence. The N-terminal sequence exhibits typical features of a cleavable chloroplast stroma-targeting sequence. The chloroplast localization of SppA was confirmed by in organello import experiments using an in vitro expression system and by immunodetection with antigen-specific antisera. Subfractionation of intact chloroplasts demonstrated that SppA is associated exclusively with thylakoid membranes, predominantly stroma lamellae, and is a part of some high molecular mass complex of about 270 kDa that exhibits proteolytic activity. Treatments with chaotropic salts and proteases showed that SppA is largely exposed to the stroma but that it behaves as an intrinsic membrane protein that may have an unusual monotopic arrangement in the thylakoids. We demonstrate that SppA is a light-inducible protease and discuss its possible involvement in the light-dependent degradation of antenna and photosystem II complexes that both involve serine-type proteases.