Pictorial Review of Fibrotic Interstitial Lung Disease on High-Resolution CT Scan and Updated Classification

TOPIC IMPORTANCE

Given the recently expanded approval of antifibrotics for various fibrotic interstitial lung diseases (ILDs), early and correct recognition of these diseases is imperative for physicians. Because high-resolution chest CT scan forms the backbone of diagnosis for ILD, this review will discuss evidence-based imaging findings of key fibrotic ILDs and an approach for differentiating these diseases.

REVIEW FINDINGS

(1) Imaging findings of nonspecific interstitial pneumonia may evolve over time and become indistinguishable from usual interstitial pneumonia. Therefore, if remote imaging can be reviewed, this would increase the likelihood of an accurate imaging diagnosis, particularly if findings appear to represent a usual interstitial pneumonia pattern on the recent examination. (2) Given the difficulty and lack of objectivity in classifying patients with hypersensitivity pneumonitis into acute, subacute, and chronic categories and that prognosis depends primarily on presence or absence of fibrosis, the new set of guidelines released in 2020 categorizes patients with hypersensitivity pneumonitis as either nonfibrotic (purely inflammatory) or fibrotic (either purely fibrotic or mixed fibrotic/inflammatory) based on imaging and/or histologic findings, and the prior temporal terms are no longer used. (3) Interstitial lung abnormalities are incidental CT scan findings that may suggest early ILD in patients without clinical suspicion for ILD. Patients with high-risk features should undergo clinical evaluation for ILD and be actively monitored for disease progression.

SUMMARY

Fibrotic ILD on high-resolution chest CT scan is a complex topic, but with use of an evidence-based analysis and algorithm as provided in this article, the probability of a correct imaging diagnosis increases.

The effectiveness and pharmacoeconomic study of using different corticosteroids in the treatment of hypersensitivity pneumonitis

PURPOSE

Interstitial lung diseases (ILDs) are caused by inflammation and/or fibrosis of alveolar walls resulting in impaired gas exchange. Hypersensitivity pneumonitis (HP) is the third most common type of ILDs. Corticosteroids are the mainstay treatment for HP. The use of intramuscular (IM) betamethasone or intravenous (IV) dexamethasone as weekly pulse doses has shown higher benefit than daily oral prednisolone for HP patients. The aim of this study is to directly compare different corticosteroids in terms of effectiveness and in monetary values and perform an economic evaluation.

METHODS

One hundred and seven patients were tested for pulmonary function tests (PFTs) and inflammatory markers to assess the treatment effectiveness. A cost-effectiveness analysis (CEA) was performed. ICERs between 3 treatment groups were calculated.

RESULTS

Post treatment, Krebs von den Lungen-6 (KL-6) levels significantly improved in betamethasone group from 723.22 ± 218.18 U/ml to 554.48 ± 129.69 U/ml (p = 0.001). A significant improvement in erythrocyte sedimentation rate (ESR) occurred in the dexamethasone group from 56.12 ± 27.97 mm to 30.06 ± 16.04 mm (p = 0.048). A significant improvement in forced expiratory volume (FEV1), forced vital capacity (FVC) and six-minute walk distance (6MWD) was observed within the three treatment groups. A significant improvement in oxygen desaturation percentage (SpO2) occurred within dexamethasone and betamethasone groups. Betamethasone and dexamethasone were found more cost-effective than prednisolone as their ICERs fell in quadrant C. Furthermore, ICER between betamethasone and dexamethasone was performed; a small difference in cost was found compared to the higher benefit of betamethasone.

CONCLUSION

Betamethasone and dexamethasone were found to be more effective than prednisolone in improving the inflammatory reaction and the clinical features of HP patients. Betamethasone was found to be the best intervention in terms of cost against the effect.

Clozapine-Induced Severe Toxicity: Exploring the Pharmacokinetic Profile of Clozapine and Its Significance in Hemodynamic Instability - A Case Report

Hemodynamic instability in patients with clozapine intoxication can indirectly reflect the serum concentration of clozapine.We have described a case of a 32-year-old pregnant woman who developed life-threatening clozapine toxicity at 28 weeks of gestation. The levels of clozapine and norclozapine in the serum were high. We initiated hemoperfusion(HP) and other detoxification therapies to remove the drug. The patient had severely dilated peripheral blood vessels, which led to cardiac symptoms such as fatal hypotension and uncontrollable tachycardia, resulting in very high cardiac output and elevated Central venous oxygen saturation (ScvO2). Pharmacological intervention significantly improved the hemodynamics.In light of our observations in the ongoing case, we posit that evaluating hemodynamic parameters before and after blood detoxification could serve as a valuable means to gauge effectiveness and provide guidance for treatment.

Distinct TNF-alpha and HLA polymorphisms associate with fibrotic and non-fibrotic subtypes of hypersensitivity pneumonitis

INTRODUCTION

Since Hypersensitivity Pneumonitis (HP) categorization in fibrotic and nonfibrotic/inflammatory types seems to be more consistent with the distinctive clinical course and outcomes, recent international guidelines recommended the use of this classification. Moreover, fibrotic subtype may share immunogenetic and pathophysiological mechanisms with other fibrotic lung diseases.

AIM

To investigate HLA -A, -B, -DRB1 and TNF-α -308 gene polymorphisms among fibrotic and nonfibrotic HP patients due to avian exposure, also in comparison with asymptomatic exposed controls.

METHODS

We prospectively enrolled 40 HP patients, classified as fibrotic or nonfibrotic/inflammatory, and 70 exposed controls. HLA and TNF-α polymorphisms were determined by polymerase chain reaction-sequence specific primer amplification.

RESULTS

While HLA alleles were not associated to HP susceptibility, fibrotic HP patients showed increased frequencies of HLA A*02 (46.7% vs 25.7%; OR=2.53, p = 0.02) and HLA DRB1*14 (10.0% vs 0.7%; OR=15.44, p=0.02) alleles when compared with exposed controls, although not statistically significant after correction for multiple comparisons. TNF-α G/G genotype (associated with low TNF-α production) frequencies were significantly increased among the non-fibrotic/inflammatory HP patients comparatively to fibrotic presentations (88% vs 60%; RR=0.44; p=0.04) and controls (88% vs 63%, OR 4.33, p=0.037). Also, these patients had a significantly increased frequency of the G allele (94.0% vs 73.3%, RR=0.44, p=0.01), while fibrotic HP patients predominantly presented the A allele (26.7% vs 6.0%, RR=2.28, p=0.01).

CONCLUSIONS

Our results support the hypothesis that fibrotic and non-fibrotic HP subtypes exhibit a distinct profile of TNF-α and HLA polymorphisms, which may be relevant to predict disease course and better define treatment strategies.

Decreased xCT activity in patients associated with Helicobacter pylori infection

Objective: In animals, Helicobacter pylori (Hp)-induced gastric injury is accompanied by a decrease in the activity of the cysteine/glutamate transporter (xCT), which regulates extracellular glutamate levels. However, the impact of xCT activity in patients with Hp infection remains unclear. This study aims to investigate variations of xCT activity in the gastric mucosa of patients with Hp infection and to provide a clinical basis for identifying targets related to Hp infection. Methods: Our study included a total of 67 patients with gastritis, which consisted of 44 Hp-negative and 23 Hp-positive peptic ulcer cases. The inclusion criteria used to select patients were as follows: gastric histology was determined with a gastroscope, antral biopsies were taken for urease tests, and pathology and culture were performed for analysis of Hp-colonization. The clinical characteristics of the patients were obtained, the expressions of microRNAs and xCT protein were detected using immune histochemical analysis, and the concentration of glutamate in their gastric secretion was determined. Results: The findings revealed that xCT expression was significantly lower in Hp-positive patients as compared to Hp-negative individuals, which was accompanied by a decrease in glutamate concentration in gastric juice. We also discovered a high expression of microRNAs that have been shown to negatively regulate xCT expression, in Hp-positive patients. Conclusion: Reduced xCT activity in patients may play an important role in gastric ulcers caused by Hp infection. Our findings suggest that the microRNA/xCT pathway could be a potential treatment target for Hp-infection-related ulcers.

Different lipid metabolic profiles and their associated genes in sessile serrated adenoma or polyps compared to hyperplastic polyps

The serrated pathway is important in the development of colorectal cancer; currently, knowledge about the lipid metabolism profiles of serrated lesions is limited. Clinical characteristics were compared via Pearson's chi-squared test, nonparametric Kruskal-Wallis test and ANOVA. For some missing values, the MCAR test and multiple imputations were performed. Compared to patients with HP, the rates of younger patients (<50) and male patients with SSA or SSP were increased (P<0.05). Additionally, the BMI index and triglyceride levels were increased in patients with SSA or SSP. Inversely, patients with SSA/P had lower levels of HDL (P<0.05). Interestingly, the value of uric acid and tumor size in SSA/P patients tended to be greater than those in HP patients, and the ratio of patients who smoked was also increased. Other characteristics, such as LDL, ALB, γ-GT, and the N/L ratio, were similar among the subtypes of serrated lesions. Analysis of GEO data (GSE43841) showed that 9 genes were associated with lipid metabolism, including ADRB3, DEGS2, PRKACB, SLC44A1, and CA4. PRKACB was downregulated in SSA/P tissue compared to HP tissue samples from the GSE76987 dataset and our hospital. In conclusion, compared to benign HP, lower HDL levels and higher triglyceride levels tended to occur in CRC precursor SSA/P lesions, and these factors may be associated with metabolic genomic markers, such as PRKACB.

Genetic Risk Factors in Early-Onset Nonalcoholic Chronic Pancreatitis: An Update

Chronic pancreatitis (CP) is a progressive, irreversible inflammatory disorder of the pancreas, which results from interrelations between different genetic and environmental factors. Genetic variants are the primary cause of the disease in early-onset nonalcoholic CP patients. Novel CP-associated genes are continuously emerging from genetic studies on CP cohorts, providing important clues for distinct mechanisms involved in CP development. On the basis of functional studies, the genetic alterations have been sub-grouped into CP-driving pathological pathways. This review focuses on the concept of CP as a complex disease driven by multiple genetic factors. We will discuss only well-defined genetic risk factors and distinct functional pathways involved in CP development, especially in the context of the early-onset nonalcoholic CP group. The diagnostic implications of the genetic testing will be addressed as well.

[Usefulness of combined sequencing of the mitochondrial genome and a targeted panel of nuclear genes involved in mitochondrial diseases]

The molecular study of mitochondrial diseases, essential for diagnosis, is special due to the dual genetic origin of these pathologies: mitochondrial DNA and nuclear DNA. Complete mtDNA sequencing still remains the first line diagnostic test followed if negative, by resequencing panels of several hundred mitochondrially-encoded nuclear genes. This strategy, with an initial entire mtDNA sequencing, is currently justified by the presence of nuclear mitochondrial DNA sequences (NUMTs) in the nuclear genome. We designed a resequencing panel combining the mtDNA and 135 nuclear genes which was evaluated compared to the performances of the standard mtDNA sequencing. Method validation was performed on the reading depth and reproducibility of the results. Thirty patients were analyzed by both methods. We were able to demonstrate that NUMTs did not impact the mtDNA sequencing quality, as the identified variants and mutant loads were identical with the reference mtDNA sequencing method. Reading depths were higher than the recommendations of the MitoDiag French diagnostic network, for the entire mtDNA for muscle and for 70% of the mtDNA for blood. These results highlight the usefulness of combining both mtDNA and mitochondrially nuclear-encoded genes and thus obtain more complete results and faster turnaround time for mitochondrial disease patients.

Interference of horse purslane (Trianthema portulacastrum L.) and other weeds affect yield of autumn planted maize (Zea mays L.)

To assess comparative losses of Trianthema portulacastrum (HP) relative to other weeds, the experiment was set during consecutive summer seasons 2018 and 2019 at the Research Farm MNS-University of Agriculture, Multan, Pakistan. Experiment consisted three replications which were laid out under randomized complete block design. Experiment consisted of ten treatments viz: weeds free (whole season), HP free till 20 Days after emergence (DAE), HP free till 40 DAE, HP free till 60 DAE, all weeds free 20 DAE, all weeds free 40 DAE, all weeds free 60 DAE, weedy check (all weeds), weedy check except HP and weedy check containing only HP. During 2018 in all weeds weedy check, maximum HP relative density (33.33%) was observed while in 2019, plot where weeds were controlled from growing till 20 DAE showed (80%) relative density at 30 DAE. HP maximum frequency (66.67%, 77.78%) and relative frequency (66%, 100%) was recorded at 45 DAE in plots where HP was kept controlled till 20 DAE and all weeds kept controlled till 20 DAE, respectively. Maximum number of grains per cob (738, 700.68), 1000 grain weight (306.66, 271.51 g) and grain yield (6150, 8015 kg hec^-1) were recorded in plots which were kept all weed free till 60 DAE. As the competition period of weeds increased over 40 DAE, it substantially reduced yield of maize. Keeping the plots HP free till 40 DAE in the maize fields with HP as the major dominating weed, likely increase in maize grain yield is up to 30% compared to the fields where HP left un attended throughout the growing season. However, if maize field is infested with a mix of weeds with more than one dominating weeds including HP, compared to weedy situation the whole season, 30% higher grain yield can be obtained if all weeds are kept controlled till 40 DAE. Hence it can be concluded that whether the farmers face heavy HP infestation only or the mix of weeds as dominating weeds, in either case farmer should control weeds within first 40 days in maize field for better grain yield.

Pharmacokinetic and bioavailability studies of α-viniferin after intravenous and oral administration to rats

Alpha-viniferin is a trimer of resveratrol and has various pharmacological activities including anti-Alzheimer's disease, anti-tuberculosis, anti-tumor, anti-inflammatory and anti-diabetic. To investigate the pharmacokinetic characteristics and absolute bioavailability of α-viniferin in rats, using naringenin as an internal standard (IS), a rapid HPLC-MS/MS method of 5 min complete run time was developed. The chromatographic separation of α-viniferin and naringenin were accomplished with Waters XBridge™ C₁₈ column (2.1 mm × 100 mm, 3.5 μm) and the mobile phase were acetonitrile and 0.1 % formic acid at a flow rate of 0.3 mL/min. Plasma samples were pretreated by ethyl acetate. The negative ion mode with electrospray ionization (ESI) source was used for detecting the sample. Oral bioavailability of α-viniferin was 4.2 %. This study will be beneficial in better understanding the pharmacological properties and the further development of α-viniferin.

Mining of Self-Organizing Map Gene-Expression Portraits Reveals Prognostic Stratification of HPV-Positive Head and Neck Squamous Cell Carcinoma

Patients (pts) with head and neck squamous cell carcinoma (HNSCC) have different epidemiologic, clinical, and outcome behaviors in relation to human papillomavirus (HPV) infection status, with HPV-positive patients having a 70% reduction in their risk of death. Little is known about the molecular heterogeneity in HPV-related cases. In the present study, we aim to disclose the molecular subtypes with potential biological and clinical relevance. Through a literature review, 11 studies were retrieved with a total of 346 gene-expression data points from HPV-positive HNSCC pts. Meta-analysis and self-organizing map (SOM) approaches were used to disclose relevant meta-gene portraits. Unsupervised consensus clustering provided evidence of three biological subtypes in HPV-positive HNSCC: Cl1, immune-related; Cl2, epithelial–mesenchymal transition-related; Cl3, proliferation-related. This stratification has a prognostic relevance, with Cl1 having the best outcome, Cl2 the worst, and Cl3 an intermediate survival rate. Compared to recent literature, which identified immune and keratinocyte subtypes in HPV-related HNSCC, we confirmed the former and we separated the latter into two clusters with different biological and prognostic characteristics. At present, this paper reports the largest meta-analysis of HPV-positive HNSCC studies and offers a promising molecular subtype classification. Upon further validation, this stratification could improve patient selection and pave the way for the development of a precision medicine therapeutic approach.

[Reasons for non-acceptance and non-use of a home telemonitoring application by multimorbid patients aged 65 years and over]

BACKGROUND

User acceptance is a key indicator and driver for the use and implementation of telemonitoring applications (TMA) in healthcare. Despite various positive effects that previous studies have revealed for users of TMA, there are always patients who discontinue their participation in a telemedicine study or even decline participation. There is little evidence for the reasons for non-acceptance and non-use of TMA, especially in multimorbid patients at the age of 65 and over in their home environment. To close this research gap, this sub-study focuses on patient-reported reasons for non-acceptance and non-use of TMA in the home environment.

METHODS

This study follows a mixed-method approach and focuses on patients' perspective. Quantitative data collection took place via computer-assisted telephone interviews among all drop-outs and non-participants. Qualitative data were collected via semi-structured interviews with drop-out patients and non-users. Eligible patients were recruited consecutively by general practitioners, informed and included in the study according to the inclusion criteria. Amongst others, patients measured their vital signs (blood pressure, heart frequency, oxygen saturation, weight) via telemedical measures and sent them via tablet to a Care Coordination Center to ascertain the need for intervention. Collected data on non-acceptance and non-use of TMA were analyzed quantitatively and qualitatively.

RESULTS

Nine general practices in two German cities included a total of 177 patients according to the inclusion criteria. During the study, 61 study participants (34.5 %) dropped out, 80 patients (31.1 %) declined participation in the study. Drop-outs and non-participants were significantly older than active participants (p=.004 and p=.001, respectively). Predominant reasons for drop-out were the lack of the perceived added value and the content-related variety of the program on the patient's tablet, the missing interest/need for telemedical monitoring as well as the time spent participating in the study. Patients living alone, single and widowed patients reported significantly more difficulties in handling the hardware (tablet) (p=.040) and the program (Motiva) (p=.013) than married and cohabiting patients. These reasons were also reported mainly by female patients, patients aged 75 years and over, and those with a low level of education.

CONCLUSION

In order to increase the acceptance and the added value of TMA for patients, the individual needs of the future target group should be analyzed at the beginning of the development. To ensure maximum user centricity, individual development steps should be continuously evaluated by the target group. TMA should be adapted to the functional abilities of elderly, multimorbid patients through, e. g., an appropriate design of the content, which is tailored to patients' individual needs. TMA should be used to an appropriate degree to avoid overburdening and should fit unobtrusively into patients' usual daily routine. For patient-specific acceptance of TMA, easy handling of the telemedical measuring and input devices is as important as the variety of offers on the platform and personal contact for technical queries. Special attention should be paid to patients who live alone, women, elderly patients over 75 years of age, and poorly educated patients in order to ensure full and easy access to technology-based telemonitoring for their own healthcare.

[The Münsteraner Memorandum on Alternative Practitioners - Analysis and evaluation of critical commentaries]

With its "Münsteraner Memorandum on Alternative Practitioners" the author collective "Münsteraner Kreis" has recently criticized current German double standards for physicians versus alternative practitioners with regard to minimal competency and to quality assurance. The authors' main goal was to attract attention to the problem and to provide systematic arguments in favor of a healthcare system that is serving patients' needs more appropriately. Reactions to the Memorandum were numerous, divergent in their evaluations, often constructive, and frequently emotionally heated. Here, we collect, analyse and evaluate only the critical voices in order to sharpen the positions presented in the Memorandum, upgrade them if necessary, and identify areas in need of further research. For greater clarity, we standardize the objections, sort them into categories, subject them to theoretical and empirical plausibility analysis, and discuss their significance for the positions we have adopted.

Assessment of the sensitivity of DQF/ZQF 2H NMR of D2O for studying modified nafion membranes at 20 °C and 80 °C

Double and zero quantum filtered (ZQF/DQF) ²H NMR spectroscopy was used to study D₂O in five different Nafion membranes, N117, N115, NR212, XL, and HP, in order to assess the effectiveness of the technique for monitoring differences in thickness, membrane reinforcement, and the addition of chemical stabilizers. Experiments were also carried out at 20 and 80 °C to understand if the ZQF/DQF technique could detect changes in the water environments and exchange dynamics as a function of temperature. For two of the membranes, significant decreases in the 1/T₂ relaxation rates were observed at 80 °C. The two modified membranes showed changes in the quadrupolar couplings when heated, with the XL membranes showing a drop in the coupling and the HP membranes showing an increase in the coupling. No consistent variations could be associated with thickness, reinforcement or the addition of stabilizers. Overall the technique was able to detect some differences between the membranes but was limited by the variability in the observed NMR data.

Copy Number Variation Analysis by Droplet Digital PCR

The health impact of many copy number variants in our genome remains still largely to be discovered. Detecting and genotyping this often complex variation presents a technical challenge. Here we describe a 96-well format droplet digital PCR (ddPCR) protocol for genotyping a common copy variant in the human haptoglobin gene. ddPCR allows for high-throughput and accurate quantitation of gene copy numbers.

Preventing metachronous gastric lesions after endoscopic submucosal dissection through Helicobacter pylori eradication

BACKGROUND AND AIM

Metachronous recurrence often occurs after endoscopic submucosal dissection for early gastric cancer, and a method for preventing recurrence is unknown. We aimed to identify risk factors for metachronous lesions, and the effects of aspirin use and Helicobacter pylori eradication on preventing recurrence.

METHODS

A total of 1041 consecutive patients who underwent endoscopic submucosal dissection for early gastric cancer between January 2007 and December 2011 were retrospectively analyzed. Every patient was examined endoscopically at 2, 6, and 12 months after endoscopic submucosal dissection, and then annually. Patients were classified into the metachronous group or non-metachronous group according to the existence of metachronous lesions and subdivided by Helicobacter pylori status into three groups: not infected, eradicated after infection, and not eradicated.

RESULTS

At 39 months' median follow-up, metachronous gastric lesions had developed in 35 patients (3.4%), including 16 with dysplasia and 19 cancers. Metachronous group were significantly older than non-metachronous group (P = 0.02). Although non-metachronous group took aspirin more frequently than metachronous group (15.5% vs 5.7%), the difference was statistically insignificant (P = 0.11). In the not eradicated group, the odds ratio of metachronous lesion was 7.762 compared with the not infected group (95% confidence interval, 1.483-60.854; P = 0.02). In the eradicated group, the odd ratio of metachronous lesion was 8.120 compared with not infected group (95% confidence interval, 1.950-58.985; P = 0.01).

CONCLUSION

Helicobacter pylori infection was an independent risk factor for metachronous gastric lesions. However, eradication of Helicobacter pylori alone does not prevent all metachronous lesions in an inflamed stomach.

Peri-conceptional obesogenic exposure induces sex-specific programming of disease susceptibilities in adult mouse offspring

Vulnerability of the fetus upon maternal obesity can potentially occur during all developmental phases. We aimed at elaborating longer-term health outcomes of fetal overnutrition during the earliest stages of development. We utilized Naval Medical Research Institute (NMRI) mice to induce pre-conceptional and gestational obesity and followed offspring outcomes in the absence of any postnatal obesogenic influences. Male adult offspring developed overweight, insulin resistance, hyperleptinemia, hyperuricemia and hepatic steatosis; all these features were not observed in females. Instead, they showed impaired fasting glucose and a reduced fat mass and adipocyte size. Influences of the interaction of maternal diet∗sex concerned offspring genes involved in fatty liver disease, lipid droplet size regulation and fat mass expansion. These data suggest that a peri-conceptional obesogenic exposure is sufficient to shape offspring gene expression patterns and health outcomes in a sex- and organ-specific manner, indicating varying developmental vulnerabilities between sexes towards metabolic disease in response to maternal overnutrition.

Health determining concepts important to people with Crohn's disease and their coverage by patient-reported outcomes of health and wellbeing

BACKGROUND AND AIMS

Busy clinical settings often restrict the possibility to focus on concepts that determine health in a positive way, commonly assessed by using patient-reported outcomes (PROs). We aimed to explore which determinants of health (DHs) are important to people with Crohn's disease (CD), to understand possible gender differences and to analyze whether these DHs are covered by PROs used in CD.

METHODS

Two systematic literature reviews were done to identify relevant DHs and clinically relevant PROs. We conducted a qualitative narrative biographical study and mapped the patients' experiences to concepts that determine health in a positive way. Experiences, DHs and the items of the PROs were compared by the WHO International Classification of Functioning, Disability and Health (ICF) as a common framework.

RESULTS

15 people with CD with a median age of 46 years (IQR 34-60) and median disease duration of 15 years (IQR 8-30) participated. Self-efficacy, social support, job satisfaction and occupational balance were mentioned most frequently. While participation appeared to have greater meaning to men, appreciation and resilience seemed to be more important for women. Of 18 PROs the Perceived Stress Questionnaire (PSQ), the Inflammatory Bowel disease - Self-efficacy scale (IBD-SES), the Life Orientation Test - Revised (LOT-R) and the Patient Activation Measure 13 (PAM-13) cover most DHs.

CONCLUSIONS

This is the first study elaborating the coverage of patient's perspective by commonly used PROs in CD. The findings could support health professionals to focus on DHs in people with CD in clinical practice and research.

Topographic and quantitative evaluation of gentamicin-induced damage to peripheral innervation of mouse cochleae

Ototoxicity induced by aminoglycoside antibiotics appears to occur both in hair cells (HCs) and the cochlear nerves that innervate them. Although HC loss can be easily quantified, neuronal lesions are difficult to quantify because two types of afferent dendrites and two types of efferent axons are tangled beneath the hair cells. In the present study, ototoxicity was induced by gentamicin in combination with the diuretic agent furosemide. Neuronal lesions were quantified in cochlear whole-mount preparations combined with microsections across the habenular perforate (HP) openings to achieve a clear picture of the topographic relationship between neuronal damage and HC loss. Multiple immunostaining methods were employed to differentiate the two types of afferent dendrites and two types of efferent axons. The results show that co-administration of gentamicin and furosemide resulted in a typical dynamic pattern of HC loss that spread from the basal turn to the outer hair cells to the apex and inner hair cells, depending on the dose and survival time after drug administration. Lesions of the innervation appeared to occur at two stages. At the early stage (2-4 days), the loss of labeling of the two types of afferent dendrites was more obvious than the loss of labeled efferent axons. At the late stage (2-4 weeks), the loss of labeled efferent axons was more rapid. In the high-dose gentamicin group, the loss of outer HCs was congruent with afferent dendrite loss at the early stage and efferent axon loss at the late stage. In the low-dose gentamicin group, the loss of labeling for cochlear innervation was more severe and widespread. Thus, we hypothesize that the gentamicin-induced damage to cochlear innervation occurs independently of hair cell loss.

Optical biopsy of sessile serrated adenomas: do these lesions resemble hyperplastic polyps under narrow-band imaging?

BACKGROUND

Serrated colorectal lesions include hyperplastic polyps (HPs) and sessile serrated adenomas (SSAs). Optical biopsy could misclassify SSAs as unimportant if they resemble HPs.

OBJECTIVE

To explore the narrow-band imaging (NBI) features of SSAs. We hypothesized that SSAs resemble HPs under NBI.

DESIGN

Retrospective analysis of data from our prospective study of NBI in routine practice.

SETTING

Single specialty group.

PATIENTS

Patients undergoing colonoscopy.

INTERVENTION

Colonoscopy.

MAIN OUTCOME MEASUREMENTS

Polyp histology prediction by community gastroenterologists. Features of SSAs versus HPs and adenomas by using the Narrow-Band Imaging International Colorectal Endoscopic (NICE) Classification.

RESULTS

Among 2388 lesions, 141 were diagnosed on pathology as SSAs, 465 as HPs, and 1546 as adenomas. Each individual NICE feature of HPs was found in 38% to 42% of SSAs, 66% to 67% of HPs, and 15% to 20% of adenomas (P < .001 for each). Each individual NICE feature of adenomas was found in 57% to 62% of SSAs, 33% to 34% of HPs, and 80% to 84% of adenomas (P < .001 for each). Compared with HPs, SSAs were less likely (odds ratio [OR] 0.74; 95% confidence interval [CI], 0.69-0.79) and adenomas were even less likely (OR 0.62; 95% CI, 0.59-0.64) to have all 3 NICE features of HPs. SSAs >5 mm were more likely than smaller SSAs to have all 3 NICE features of adenomas. SSA location did not predict NBI features. Analyses restricted to high-confidence lesions showed similar results.

LIMITATIONS

The endoscopists were not NBI experts.

CONCLUSION

Community gastroenterologists observed a profile of NICE features among SSAs that was intermediate to the profiles observed for HPs and adenomas. These results require confirmation by NBI experts.

Peri-conceptional obesogenic exposure induces sex-specific programming of disease susceptibilities in adult mouse offspring

Vulnerability of the fetus upon maternal obesity can potentially occur during all developmental phases. We aimed at elaborating longer-term health outcomes of fetal overnutrition during the earliest stages of development. We utilized Naval Medical Research Institute (NMRI) mice to induce pre-conceptional and gestational obesity and followed offspring outcomes in the absence of any postnatal obesogenic influences. Male adult offspring developed overweight, insulin resistance, hyperleptinemia, hyperuricemia and hepatic steatosis; all these features were not observed in females. Instead, they showed impaired fasting glucose and a reduced fat mass and adipocyte size. Influences of the interaction of maternal diet∗sex concerned offspring genes involved in fatty liver disease, lipid droplet size regulation and fat mass expansion. These data suggest that a peri-conceptional obesogenic exposure is sufficient to shape offspring gene expression patterns and health outcomes in a sex- and organ-specific manner, indicating varying developmental vulnerabilities between sexes towards metabolic disease in response to maternal overnutrition.

Thermal and tactile interactions in the perception of local skin wetness at rest and during exercise in thermo-neutral and warm environments

The central integration of thermal (i.e. cold) and mechanical (i.e. pressure) sensory afferents is suggested as to underpin the perception of skin wetness. However, the role of temperature and mechanical inputs, and their interaction, is still unclear. Also, it is unknown whether this intra-sensory interaction changes according to the activity performed or the environmental conditions. Hence, we investigated the role of peripheral cold afferents, and their interaction with tactile afferents, in the perception of local skin wetness during rest and exercise in thermo-neutral and warm environments. Six cold-dry stimuli, characterized by decreasing temperatures [i.e. -4, -8 and -15 °C below the local skin temperature (T(sk))] and by different mechanical pressures [i.e. low pressure (LP): 7 kPa; high pressure (HP): 10 kPa], were applied on the back of 8 female participants (age 21 ± 1 years), while they were resting or cycling in 22 or 33 °C ambient temperature. Mean and local Tsk, thermal and wetness perceptions were recorded during the tests. Cold-dry stimuli produced drops in Tsk with cooling rates in a range of 0.06-0.4 °C/s. Colder stimuli resulted in increasing coldness and in stimuli being significantly more often perceived as wet, particularly when producing skin cooling rates of 0.18 °C/s and 0.35 °C/s. However, when stimuli were applied with HP, local wetness perceptions were significantly attenuated. Wetter perceptions were recorded during exercise in the warm environment. We conclude that thermal inputs from peripheral cutaneous afferents are critical in characterizing the perception of local skin wetness. However, the role of these inputs might be modulated by an intra-sensory interaction with the tactile afferents. These findings indicate that human sensory integration is remarkably multimodal.

Mechanisms of enhanced neutralization of botulinum neurotoxin by monoclonal antibodies conjugated to antibodies specific for the erythrocyte complement receptor

Immune complexes formed between monoclonal antibodies (mAbs) and toxins can neutralize toxicity in vivo by multiple mechanisms. Toxin sequestration and clearance by mAbs may be improved by enhancing their ability to bind to red blood cells (RBCs) through immune adherence. This can be achieved by converting the mAbs to heteropolymers (HPs), which are antigen-specific mAbs cross-linked to mAbs targeting the complement receptor (CR1), a protein that is expressed on the surface of RBCs in primates and mediates delivery of complement C3b-containing immune complexes to tissue macrophages. Conversion of mAbs to HPs has been shown to enhance clearance of multivalent antigens from the blood circulation, but the interaction of HPs with monovalent toxins has not been examined. Using botulinum neurotoxin (BoNT) as a model system, we studied the effect of conversion of a pair of BoNT-specific mAbs into HPs on toxin neutralization and handling in vivo. Two HPs given in combination had 166-fold greater potency than un-modified mAbs, neutralizing 5000 LD50 BoNT, when tested in transgenic mice expressing human CR1 on RBC membranes. Improvement required adherence of BoNT to the RBC in vivo and 2 HPs, rather than an HP+mAb pair. The HP pair bound BoNT to RBCs in the circulation for 2h, in comparison to BoNT-neutralizing anti-serum, which induced no detectable RBC binding. HP pairs exhibited enhanced uptake by peritoneal macrophages in vitro, compared to pairs of mAbs or mAb+HP pairs. In a post-exposure therapeutic model, HPs gave complete protection from a lethal BoNT dose up to 3h after toxin exposure. In a pre-exposure prophylaxis model, mice given HP up to 5 days prior to BoNT administration were fully protected from a lethal BoNT dose. These studies elucidate general mechanisms for the neutralization of toxins by HP pairs and demonstrate the potential utility of HPs as BoNT therapeutics.

Prolyl carboxypeptidase mRNA expression in the mouse brain

Prolyl carboxypeptidase (PRCP), a serine protease, is widely expressed in the body including liver, lung, kidney and brain, with a variety of known substrates such as plasma prekallikrein, bradykinin, angiotensins II and III, and α-MSH, suggesting its role in the processing of tissue-specific substrates. In the brain, PRCP has been shown to inactivate hypothalamic α-MSH, thus modulating melanocortin signaling in the control of energy metabolism. While its expression pattern has been reported in the hypothalamus, little is known on the distribution of PRCP throughout the mouse brain. This study was undertaken to determine PRCP expression in the mouse brain. Radioactive in situ hybridization was performed to determine endogenous PRCP mRNA expression. In addition, using a gene-trap mouse model for PRCP deletion, X-gal staining was performed to further determine PRCP distribution. Results from both approaches showed that PRCP gene is broadly expressed in the brain.

Corticotropin-releasing factor receptor type-2 is involved in the cocaine-primed reinstatement of cocaine conditioned place preference in rats

Here we explored the in vivo role of brain corticotropin-releasing factor receptor type-2 (CRFR2) in cocaine-primed reinstatement of drug seeking. Conditioned place preference (CPP) procedure was used to assess the acquisition, extinction and reinstatement of cocaine-seeking behavior in rats. First, expressions of CRFR2 were shown to be affected in a brain region-specific manner within cocaine-induced CPP and cocaine-extinct CPP models. Bilateral blockade of CRFR2 in the dorsal portion of the medial prefrontal cortex (mPFC), or hippocampus (HP) was partially inhibited, but in the dorsal striatum (DS) did not affect, the cocaine-primed reinstatement of cocaine CPP.

The matricellular protein periostin contributes to proper collagen function and is downregulated during skin aging

BACKGROUND

Periostin is a secreted 90kDa matricellular protein, which is predominantly expressed in collagen-rich tissues. Collagen is the most abundant protein in mammals and has great tensile strength. Recent investigations have shown that periostin influences collagen fibrillogenesis and biomechanical properties of murine connective tissues.

OBJECTIVE

We investigated the function of periostin concerning collagen homeostasis during intrinsic and extrinsic skin aging. For this purpose, human skin samples of young and old donors as well as samples of photoaged and sun-protected skin areas were analyzed for periostin expression. Using in vitro models, we determined the cell types responsible for periostin expression and performed functional analyses with periostin knockdown cells.

METHODS

TaqMan Real-Time PCR, UV irradiation, knockdown experiments, immunostaining, electron microscopy, collagen degradation assay, collagen crosslink analysis.

RESULTS

Periostin expression is highest in the papillary dermis and downregulated during skin aging. Fibroblasts and non-follicular skin derived precursors were identified as main source for periostin expression in human skin. Periostin knockdown in fibroblasts has no effect on collagen expression, but results in an increased fibril diameter and aberrant collagen structure. This leads to an increased susceptibility of collagen toward proteases, whereas recombinant periostin protects collagen fibrils from degradation.

CONCLUSION

Our data show that periostin plays an important role for proper collagen assembly and homeostasis. During skin aging periostin expression decreases and contributes to the phenotype of aged skin.

Interleukin-1β induced by Helicobacter pylori infection enhances mouse gastric carcinogenesis. Cancer Lett. 2013;340:141-147. [PMID: 23920123 DOI: 10.1016/j.canlet.2013.07.034]

Interleukin-1β (Il1b) is considered to be involved in Helicobacter pylori (HP)-induced human gastric carcinogenesis, while the role of its polymorphisms in gastric cancer susceptibility remains controversial. Here, we aimed to clarify the role of HP infection-induced IL1B in gastric inflammation and carcinogenesis using Il1b(-/-) (Il1b-null) mice. In gastric mucosa of the Il1b(+/+) (WT) mice, HP infection induced Il1b expression and severe inflammation. In contrast, in Il1b-null mice, recruitment of neutrophils and macrophages by HP infection was markedly suppressed. In a carcinogenicity test, the multiplicity of gastric tumors was significantly suppressed in theIl1b-null mice (58% of WT; P<0.005). Mechanistically, HP infection induced NF-κB activation both in the inflammatory and epithelial cells in gastric mucosae, and the activation was attenuated in the Il1b-null mice. Accordingly, increased proliferation and decreased apoptosis of gastric epithelial cells induced by HP infection in the WT mice were attenuated in the Il1b-null mice. These results demonstrated that the IL1B physiologically induced by HP infection enhanced gastric carcinogenesis by affecting both inflammatory and epithelial cells.

Relationship of colonoscopy-detected serrated polyps with synchronous advanced neoplasia in average-risk individuals

BACKGROUND

Serrated cancers account for 10% to 20% of all colorectal cancers (CRC) and more than 30% of interval cancers. The presence of proximal serrated polyps and large (≥10 mm) serrated polyps (LSP) has been correlated with colorectal neoplasia.

OBJECTIVE

To evaluate the prevalence of serrated polyps and their association with synchronous advanced neoplasia in a cohort of average-risk population and to assess the efficacy of one-time colonoscopy and a biennial fecal immunochemical test for reducing CRC-related mortality. This study focused on the sample of 5059 individuals belonging to the colonoscopy arm.

DESIGN

Multicenter, randomized, controlled trial.

SETTING

The ColonPrev study, a population-based, multicenter, nationwide, randomized, controlled trial.

PATIENTS

A total of 5059 asymptomatic men and women aged 50 to 69 years.

INTERVENTION

Colonoscopy.

MAIN OUTCOME MEASUREMENTS

Prevalence of serrated polyps and their association with synchronous advanced neoplasia.

RESULTS

Advanced neoplasia was detected in 520 individuals (10.3%) (CRC was detected in 27 [0.5%] and advanced adenomas in 493 [9.7%]). Serrated polyps were found in 1054 individuals (20.8%). A total of 329 individuals (6.5%) had proximal serrated polyps, and 90 (1.8%) had LSPs. Proximal serrated polyps or LSPs were associated with male sex (odds ratio [OR] 2.08, 95% confidence interval [CI], 1.76-4.45 and OR 1.65, 95% CI, 1.31-2.07, respectively). Also, LSPs were associated with advanced neoplasia (OR 2.49, 95% CI, 1.47-4.198), regardless of their proximal (OR 4.15, 95% CI, 1.69-10.15) or distal (OR 2.61, 95% CI, 1.48-4.58) locations. When we analyzed subtypes of serrated polyps, proximal hyperplasic polyps were related to advanced neoplasia (OR 1.61, 95% CI, 1.13-2.28), although no correlation with the location of the advanced neoplasia was observed.

LIMITATIONS

Pathology criteria for the diagnosis of serrated polyps were not centrally reviewed. The morphology of the hyperplasic polyps (protruded or flat) was not recorded. Finally, because of the characteristics of a population-based study carried out in average-risk patients, the proportion of patients with CRC was relatively small.

CONCLUSION

LSPs, but not proximal serrated polyps, are associated with the presence of synchronous advanced neoplasia. Further studies are needed to determine the risk of proximal hyperplastic polyps.

Involvement of the α7-nicotinic acetylcholine receptors in the anti-inflammatory action of the thymulin-related peptide (PAT)

BACKGROUND AND PURPOSE

Peptide analog of thymulin (PAT) has been shown to have anti-hyperalgesic and anti-inflammatory properties in animal models of inflammation. Recent reports suggest that the peripheral cholinergic system has an anti-inflammatory role mediated by α7-nicotinic acetylcholine receptor (α7-nAChR). Our aim is to investigate whether the action of PAT is mediated, via the cholinergic pathway.

EXPERIMENTAL APPROACH

The anti-hyperalgesic and anti-inflammatory action of PAT was assessed in rat models of inflammatory nociceptive hyperactivity (carrageenan and endotoxin) and in a mice air-pouch model for localized inflammation, respectively; the possible attenuation of PAT's effects by pretreatment with the α7-nAchR specific antagonist methyllycaconitine citrate (MLA) was also investigated. In another series of experiments, using two electrode recordings, the effect of PAT on the α7-nAChRs, expressed in Xenopus Oocytes, was also determined.

KEY RESULTS

Administration of PAT reversed inflammatory nociceptive hyperactivity and cold and tactile hyperactivity in rats. This effect was partially or totally prevented by MLA, as assessed by different behavioral pain tests. Treatment with PAT also reduced the alteration of cytokines and NGF levels by carrageenan injection in the mouse air pouch model; this effect was partially antagonized by MLA. Electrophysiological recording demonstrated that PAT significantly potentiated the α7-nAchR expressed in Xenopus Oocytes. These effects were not observed when a control peptide, with a reverse sequence (rPAT), was utilized.

CONCLUSIONS AND IMPLICATIONS

The behavioral and electrophysiological observations described in this report demonstrate that PAT mediates, at least partially, its anti-inflammatory action by potentiating the α7-nAChR. These results indicate that PAT has a potential for new therapeutic applications as anti-inflammatory and analgesic agent.

Regional, but not total, body composition changes in overweight and obese adults consuming a higher protein, energy-restricted diet are sex specific

Secondary analyses of data from 2 studies were used to assess the effects of protein intake and sex on diet-induced changes in body composition. The primary hypothesis was that the changes of body composition via energy restriction (ie, lean body mass [LBM], fat mass [FM], and bone) would be sex and diet specific. For 12 weeks, 43 male (study 1) and 45 female (study 2) overweight and obese adults consumed an energy-deficit diet (750 kcal/d less than energy needs) containing either 0.8 (normal protein [NP], 21 men and 23 women) or 1.4 g protein∙kg(-1)∙d(-1) (high protein [HP], 22 men and 22 women). Body composition measurements were performed at preintervention and postintervention. Over time, all research participants lost weight, LBM, and FM. Independent of protein intake, the men lost more LBM in the trunk (-0.9 vs -0.5 kg) and less in the legs (-1.5 vs -1.1 kg) compared with the women (P < .05). Independent of sex, the HP group lost less LBM in the trunk and legs than the NP group. These sex and protein intake responses resulted in the NP men losing the most LBM in the legs and the NP women losing the most LBM in the trunk. Over time, men lost more FM (-5.0 vs -3.9 kg) from the trunk and less from legs (-1.7 vs -2.1 kg) than women (P < .05), which resulted in a greater decrease of the android-to-gynoid fat ratio for the men. Protein intake did not influence these sex-specific responses or have any independent effects on changes in FM. In addition, protein intake did not influence bone mineral density responses over time; bone mineral density was reduced in women, but not in men. These findings indicate that higher protein intake during weight loss promotes the retention of LBM in both the trunk and legs despite the sex-specific changes in these body regions.

Impact of brain tissue filtering on neurostimulation fields: a modeling study

Electrical neurostimulation techniques, such as deep brain stimulation (DBS) and transcranial magnetic stimulation (TMS), are increasingly used in the neurosciences, e.g., for studying brain function, and for neurotherapeutics, e.g., for treating depression, epilepsy, and Parkinson's disease. The characterization of electrical properties of brain tissue has guided our fundamental understanding and application of these methods, from electrophysiologic theory to clinical dosing-metrics. Nonetheless, prior computational models have primarily relied on ex-vivo impedance measurements. We recorded the in-vivo impedances of brain tissues during neurosurgical procedures and used these results to construct MRI guided computational models of TMS and DBS neurostimulatory fields and conductance-based models of neurons exposed to stimulation. We demonstrated that tissues carry neurostimulation currents through frequency dependent resistive and capacitive properties not typically accounted for by past neurostimulation modeling work. We show that these fundamental brain tissue properties can have significant effects on the neurostimulatory-fields (capacitive and resistive current composition and spatial/temporal dynamics) and neural responses (stimulation threshold, ionic currents, and membrane dynamics). These findings highlight the importance of tissue impedance properties on neurostimulation and impact our understanding of the biological mechanisms and technological potential of neurostimulatory methods.

The gait variability index: a new way to quantify fluctuation magnitude of spatiotemporal parameters during gait

This article describes a conglomerate measure of gait variability based on nine spatiotemporal parameters: the Gait Variability Index (GVI). Concurrent validity, inter-session reliability and minimum detectable change (MDC) were evaluated in 31 patients with Friedreich's Ataxia (FRDA), through comparisons with classically used evaluation tools such as the International Cooperative Ataxia Rating Scale (ICARS). GVI scores for the healthy population were 100.3±8.6 and were significantly reduced in FRDA patients (70.4±7.9). The GVI was correlated with the global ICARS score and was sensitive enough to differentiate between groups of FRDA patients categorized by the Posture and Gait Disturbances sub-score. The GVI was found to have a high inter-session reliability with an intraclass correlation coefficient of 0.91. A MDC of 8.6 points was found necessary to ensure that a change in GVI reflects a true change rather than measurement error. The GVI provides a quantitative measure of variability which behaves well statistically in both HP and patients with FRDA. It can be easily implemented using the supplemental data provided with this article. Complementary work is necessary to strengthen the GVI validation.

Apolipoprotein(a) acts as a chemorepellent to human vascular smooth muscle cells via integrin αVβ3 and RhoA/ROCK-mediated mechanisms

Lipoprotein(a) (Lp(a)) is an independent risk factor for the development of cardiovascular disease. Vascular smooth muscle cell (SMC) motility and plasticity, functions that are influenced by environmental cues, are vital to adaptation and remodelling in vascular physiology and pathophysiology. Lp(a) is reportedly damaging to SMC function via unknown molecular mechanisms. Apolipoprotein(a) (apo(a)), a unique glycoprotein moiety of Lp(a), has been demonstrated as its active component. The aims of this study were to determine functional effects of recombinant apo(a) on human vascular SMC motility and explore the underlying mechanism(s). Exposure of SMC to apo(a) in migration assays induced a potent, concentration-dependent chemorepulsion that was RhoA and integrin αVβ3-dependent, but transforming growth factor β-independent. SMC manipulation through RhoA gene silencing, Rho kinase inhibition, statin pre-treatment, αVβ3 neutralising antibody and tyrosine kinase inhibition all markedly inhibited apo(a)-mediated SMC migration. Our data reveal unique and potent activities of apo(a) that may negatively influence SMC remodelling in cardiovascular disease. Circulating levels of Lp(a) are resistant to lipid-lowering strategies and hence a greater understanding of the mechanisms underlying its functional effects on SMC may provide alternative therapeutic targets.

Defining RNA motif-aminoglycoside interactions via two-dimensional combinatorial screening and structure-activity relationships through sequencing

RNA is an extremely important target for the development of chemical probes of function or small molecule therapeutics. Aminoglycosides are the most well studied class of small molecules to target RNA. However, the RNA motifs outside of the bacterial rRNA A-site that are likely to be bound by these compounds in biological systems is largely unknown. If such information were known, it could allow for aminoglycosides to be exploited to target other RNAs and, in addition, could provide invaluable insights into potential bystander targets of these clinically used drugs. We utilized two-dimensional combinatorial screening (2DCS), a library-versus-library screening approach, to select the motifs displayed in a 3×3 nucleotide internal loop library and in a 6-nucleotide hairpin library that bind with high affinity and selectivity to six aminoglycoside derivatives. The selected RNA motifs were then analyzed using structure-activity relationships through sequencing (StARTS), a statistical approach that defines the privileged RNA motif space that binds a small molecule. StARTS allowed for the facile annotation of the selected RNA motif-aminoglycoside interactions in terms of affinity and selectivity. The interactions selected by 2DCS generally have nanomolar affinities, which is higher affinity than the binding of aminoglycosides to a mimic of their therapeutic target, the bacterial rRNA A-site.

Changes of calcium binding proteins, c-Fos and COX in hippocampal formation and cerebellum of Niemann-Pick, type C mouse

Niemann-Pick disease, type C (NPC) is an intractable disease that is accompanied by ataxia, dystonia, neurodegeneration, and dementia due to an NPC gene defect. Disruption of calcium homeostasis in neurons is important in patients with NPC. Thus, we used immunohistochemistry to assess the expression levels of calcium binding proteins (calbindin D28K, parvalbumin, and calretinin), c-Fos and cyclooxygenase-1,2 (COX-1,2) in the hippocampal formation and cerebellum of 4 and 8 week old NPC+/+, NPC+/-, and NPC-/- mice. General expression of these proteins decreased in the hippocampus and cerebellum of NPC-/- compared to that in both young and adult NPC+/+ or NPC+/- mice. Parvalbumin, COX-1,2 or c-Fos-immunoreactive neurons were widely detected in the CA1, CA3, and DG of the hippocampus, but the immunoreactivities were decreased sharply in all areas of hippocampus of NPC-/- compared to NPC+/+ and NPC+/- mice. Taken together, reduction of these proteins may be one of the strong phenotypes related to the neuronal degeneration in NPC-/- mice.

Volumetric properties underlying ligand binding in a monomeric hemoglobin: a high-pressure NMR study

The 2/2 hemoglobin of the cyanobacterium Synechococcus sp. PCC 7002, GlbN, coordinates the heme iron with two histidines and exists either with a b heme or with a covalently attached heme. The binding of exogenous ligands displaces the distal histidine and induces a conformational rearrangement involving the reorganization of internal void volumes. The formation of passageways within the resulting conformation is thought to facilitate ligand exchange and play a functional role. Here we monitored the perturbation induced by pressure on the ferric bis-histidine and cyanide-bound states of GlbN using (1)H-(15)N HSQC NMR spectroscopy. We inspected the outcome with a statistical analysis of 170 homologous 2/2 hemoglobin sequences. We found that the compression landscape of GlbN, as represented by the variation of an average chemical shift parameter, was highly sensitive to ligand swapping and heme covalent attachment. Stabilization of rare conformers was observed at high pressures and consistent with cavity redistribution upon ligand binding. In all states, the EF loop was found to be exceptionally labile to pressure, suggesting a functional role as a semi-flexible hinge between the adjacent helices. Finally, coevolved clusters presented a common pattern of compensating pressure responses. The high-pressure dissection combined with protein sequence analysis established locations with volumetric signatures relevant to residual communication of 2/2 hemoglobins. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.