Acidified seawater impacts sea urchin larvae pH regulatory systems relevant for calcification

Calcifying echinoid larvae respond to changes in seawater carbonate chemistry with reduced growth and developmental delay. To date, no information exists on how ocean acidification acts on pH homeostasis in echinoderm larvae. Understanding acid–base regulatory capacities is important because intracellular formation and maintenance of the calcium carbonate skeleton is dependent on pH homeostasis. Using H⁺-selective microelectrodes and the pH-sensitive fluorescent dye BCECF, we conducted in vivo measurements of extracellular and intracellular pH (pH_e and pH_i) in echinoderm larvae. We exposed pluteus larvae to a range of seawater CO₂ conditions and demonstrated that the extracellular compartment surrounding the calcifying primary mesenchyme cells (PMCs) conforms to the surrounding seawater with respect to pH during exposure to elevated seawater pCO₂. Using FITC dextran conjugates, we demonstrate that sea urchin larvae have a leaky integument. PMCs and spicules are therefore directly exposed to strong changes in pH_e whenever seawater pH changes. However, measurements of pH_i demonstrated that PMCs are able to fully compensate an induced intracellular acidosis. This was highly dependent on Na⁺ and HCO₃⁻, suggesting a bicarbonate buffer mechanism involving secondary active Na⁺-dependent membrane transport proteins. We suggest that, under ocean acidification, maintained pH_i enables calcification to proceed despite decreased pH_e. However, this probably causes enhanced costs. Increased costs for calcification or cellular homeostasis can be one of the main factors leading to modifications in energy partitioning, which then impacts growth and, ultimately, results in increased mortality of echinoid larvae during the pelagic life stage.     

Shwachman syndrome: Exocrine pancreatic dysfunction and variable phenotypic expression

BACKGROUND & AIMS: Shwachman syndrome is an inherited condition with multisystemic abnormalities, including exocrine pancreatic dysfunction. The aim of this study was to evaluate the occurrence and progression of features in a large cohort of patients. METHODS: Clinical records of 25 patients with Shwachman syndrome were reviewed. RESULTS: Mean birth weight (2.92 +/- 0.51 kg) was at the 25th percentile. However, by 6 months of age, mean heights and weights were less than the 5th percentile. After 6 months of age, growth velocity was normal. Severe fat maldigestion due to pancreatic insufficiency was present in early life (fecal fat, 26% +/- 17% of fat intake; age, < 2 years). Serial assessment of exocrine pancreatic function showed persistent deficits of enzyme secretion, but 45% of patients showed moderate age-related improvements leading to pancreatic sufficiency. Neutropenia was the most common hematologic abnormality (88%), but leukopenia, thrombocytopenia, and anemia were also frequently encountered. Patients with hypoplasia of all three bone marrow cellular lines (n = 11) had the worst prognosis; 5 patients died, 2 of sepsis and 3 of acute myelogenous leukemia. Other findings included hepatomegaly and/or abnormal liver function test results and skeletal abnormalities. CONCLUSIONS: A wide and varied spectrum of phenotypic abnormalities among patients with Shwachman syndrome is described. Pancreatic acinar dysfunction is an invariable abnormality. Patients with severe bone marrow involvement may have a guarded prognosis. (Gastroenterology 1996 Dec;111(6):1593-602)     

Do changes in visceral sensory function determine the development of dyspepsia during treatment with aspirin?

BACKGROUND & AIMS: We hypothesized that the development of dyspeptic symptoms during treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) would be linked to alterations in gastric mechanosensory function and gastric emptying. METHODS: In the first study, gastric mechanosensory thresholds (barostat technique) and gastric emptying ((13)C-octanoic breath test) were measured and endoscopy was performed at entry and after 5 days of treatment with aspirin (500 mg 3 times daily) in 8 patients with functional dyspepsia (initially without symptoms) and 8 healthy controls. In a second, double-blind, placebo-controlled, cross-over study, 6 new patients with functional dyspepsia and 6 controls were started with either placebo or aspirin for 5 days. Sensory thresholds were tested after the fifth day of aspirin or placebo treatment. Abdominal symptoms were assessed daily. RESULTS: In the first study, 6 of 8 patients and 3 of 8 controls, and in the second trial 6 of 6 patients and 1 of 6 healthy subjects, developed dyspepsia on aspirin (P < 0.005 patients vs. healthy subjects). No symptoms occurred during placebo treatment. Lanza scores were not associated with symptoms. After aspirin, sensory thresholds increased in both studies in subjects without development of symptoms (by 25.9% +/- 7.9%, and 31.0% +/- 4.1%, respectively, all P < 0.05), whereas there was no significant increase in subjects who developed symptoms (-11.2% +/- 5.3% and -3.4% +/- 13.4%, all P > 0.4). Neither thresholds nor symptoms were linked with the severity of mucosal damage, baseline gastric emptying (t1/2), or changes of gastric emptying (all P > 0.4). CONCLUSIONS: Failure to increase sensory thresholds during treatment with aspirin is associated with the development of dyspepsia.     

X-linked chronic granulomatous disease: correction of NADPH oxidase defect by retrovirus-mediated expression of gp91-phox

Chronic granulomatous disease (CGD) is an inherited immunodeficiency resulting from the inability of an individual's phagocytes to produce superoxide anions because of defective NADPH oxidase. The disease may be treated by bone marrow transplantation and as such is a candidate for somatic gene therapy. Two thirds of patients have defects in an X- linked gene (X-CGD) encoding gp91-phox, the large subunit of the membrane cytochrome b-245 component of NADPH oxidase. Epstein-Barr virus-transformed B-cell lines from patients with CGD provide a model system for the disease. We have used retrovirus-mediated expression of gp91-phox to reconstitute functionally NADPH oxidase activity in B-cell lines from three unrelated patients with X-CGD. The protein is glycosylated and membrane associated, and the reconstituted oxidase is appropriately activated via protein kinase C. The kinetics of superoxide production by such reconstituted cells is similar to that of normal B-cell lines. These data show the potential of gene therapy for this disease.     

Das mukosale Immunsystem

Zum Thema Untersuchungen der letzten 10 Jahre haben zu einem verbesserten Verst?ndnis der Pathophysiologie von chronisch entzündlichen Darmerkrankungen geführt. Neuere Studien belegen hierbei v. a. die funktionelle Bedeutung einer Aktivierung des mukosalen Immunsystems durch bakterielle Antigene für die Pathogenese der chronisch entzündlichen Darmerkrankungen (CED). Neben Chemokinen und Adh?sionsmolekülen scheinen vor allem Zytokine, die von antigenpr?sentierenden Zellen und T-Lymphozyten produziert werden, pathogenetisch für die CED von entscheidender Bedeutung zu sein. So konnte tierexperimentell gezeigt werden, dass Antik?rper gegen proinflammatorische Zytokine zu einer Suppression von chronisch intestinalen Entzündungsreaktionen führen k?nnen, was durch eine Induktion von T-Zellapoptose bedingt ist. Basierend auf neuen Erkenntnissen zur Immunpathogenese der CED werden klinisch zzt. innovative Therapiekonzepte getestet, die z. B. rekombinante antiinflammatorische Zytokine und neutralisierende Antik?rper gegen proinflammatorische Zytokine und ihre Rezeptoren umfassen. Trotz dieser Fortschritte im Verst?ndnis der Pathophysiologie und der Bedeutung des mukosalen Immunsystems bleiben jedoch zahlreiche Fragen über die molekulare Immunpathogenese der CED offen und bedürfen weiterer Untersuchung. Prof. Dr. Markus Neurath 1. Medizinische Klinik und Poliklinik, Johannes-Gutenberg-Universit?t, Langenbeckstra?e 1, 55 131 Mainz, E-Mail: neurath@1-med.klinik.uni-mainz.de     

Mental stress and gastric acid secretion

In 14 healthy male volunteers, we studied the influence of acute mental (=psychological) stress induced by performing mental arithmetic and solving anagrams against a financial reward on endogenously stimulated gastric acid output. Personality factors were determined by the Personality Research Form. Acute mental stress significantly (P<0.05) increased systolic blood pressure (+8.9±2.0 mm Hg±sem) and heart rate (+5.3±1.6 beatslmin). The mean gastric acid output during the mental stress period (17.9±2.7 mmol/32 min) did not significantly differ from pre- (16.9±2.3 mmol/32 min) and poststress (18.1±2.2 mmol/32 min) values. However, detailed analysis revealed that mental stress induced contrary changes of gastric acid output in different subjects. About half the individuals reacted with a decrease (up to 60%) and the other half with an increase (up to 60%) in acid output. In some individuals the changes of gastric acid output were very small. By multiple correlations, impulsivity was identified as the personality trait with the highest correlation coefficient (r=0.82) with changes of gastric acid output during the acute mental stress period. During the mental stress period, gastric acid output increased in subjects with high scores on the impulsivity scale, but significantly decreased in those with low scores. We conclude that (1) there is a great individual variability in gastric acid response to acute mental stress, and (2) this variability may be partly attributed to differences in personality traits.     

Detection of genomic deletions of PKP2 in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited myocardial disease that predominantly affects the right ventricle and is associated with ventricular arrhythmias that may lead to sudden cardiac death. Mutations within at least seven separate genes have been identified to cause ARVC, however a genetic culprit remains elusive in approximately 50% of cases. Although negative genetic testing may be secondary to pathogenic mutations within undiscovered genes, an alternative explanation may be the presence of large deletions or duplications involving known genes. These large copy number variants may not be detected with standard clinical genetic testing which is presently limited to direct DNA sequencing. We describe two cases of ARVC possessing large deletions involving plakophilin‐2 (PKP2) identified with microarray analysis and/or multiplex ligation‐dependent probe amplification (MLPA) that would have been classified as genotype negative with standard clinical genetic testing. A deletion of the entire coding region of PKP2 excluding exon 1 was identified in patient 1 and his son. In patient 2, MLPA analysis of PKP2 revealed deletion of the entire gene with subsequent microarray analysis demonstrating a de novo 7.9 Mb deletion of chromosome 12p12.1p11.1. These findings support screening for large copy number variants in clinically suspected ARVC cases without clear disease causing mutations following initial sequencing analysis.     

Towards a consensus for classification of mandibular condyle fractures

The merits of surgical treatment of fractures of the mandibular condyle versus non-surgical management remains highly controversial, despite a large volume of literature dedicated to this topic. One reason the controversy remains, is because most of the outcomes in the literature are not directly comparable. The disparate range of condylar fracture classifications used is one of the reasons that studies are not comparable. We sought to review classification systems for condylar fractures used in the recent scientific literature.Review of the literature from 2016 to 2019, looking for papers relating to fractures of the mandibular condyle. Papers identified were assessed for type of study, focus of study, classification system used.88 studies were identified, including prospective and retrospective cohort studies, randomised and non-randomised prospective studies, randomised controlled trials and case series. More studies focussed on epidemiological factors than surgical access, fixation or outcomes. 31 used no classification system, whilst 17 used unique classification systems and 40 used previously referenced classification systems.Classification systems are used to help separate clinical problems into distinguishable groups, where there is a difference in management or outcome depending on the distinguishing features.There is currently a wide diversity of classification systems used for condyle fractures, and as a result, comparisons of surgical access, fixation and outcomes are difficult to make. Having a single classification system across the published literature would allow easier comparison and the classification proposed by the AO group is recommended for future use.     

Hematopoietic growth factor expression and ATRA sensitivity in acute promyelocytic blast cells

Acute promyelocytic leukemia (APL) is a homogeneous subgroup of acute myeloid leukemias (AMLs) characterized by the presence of the t(15,17) translocation and the resulting promyelocytic myeloid leukemia/retinoic acid receptor alpha (PML/RAR alpha) fusion proteins. To date APL is the only AML that is sufficiently sensitive to all-trans retinoic acid's (ATRA) differentiating effect. In vivo ATRA alone achieves complete remission in most APL patients. However, failure or partial responses are observed and the molecular basis of the absence of ATRA response in these patients has not been determined. To gain insights in the cell growth and differentiation of APL cells, expression of hematopoietic growth factors (HGF) shown to be produced by leukemic cells (interleukin-1 beta [IL-1 beta], IL-6, tumor necrosis factor alpha (TNF alpha), granulocyte colony-stimulating factor [G-CSF], granulocyte- macrophage colony-stimulating factor [GM-CSF], and IL-3) was studied in 16 APL samples. Twelve APL cases expressed IL-1 beta, IL-6, and TNF alpha, but not G-CSF, GM-CSF, and IL-3. These cases achieved complete remission with ATRA therapy. The four remaining patients (either TNF alpha negative or G-CSF, GM-CSF or IL-3 positive) did not achieve complete remission with ATRA. In all cases, in vivo response to ATRA therapy was correlated to the in vitro differentiation effect of all- trans retinoic acid 10(-6) mol/L. Thus, ATRA differentiation induction was strongly correlated to the HGF expression (P < .0001). These results suggest that the presence or absence of HGF's expression by APL cells may contribute to the therapeutic effect of ATRA in this disease.