Males Have Higher Rates of Peri-operative Mortality Following Surgery for Osteoporotic Vertebral Compression Fracture

In this study, we evaluated the association between sex and the incidence of postoperative mortality in the peri-operative period following surgical intervention for OVCF. We found no statistical association between surgical complications and patient sex. However, males exhibited higher rates of mortality and 30-day readmissions relative to females.

INTRODUCTION

Osteoporotic vertebral compression fractures (OVCF) contribute substantially to the financial burden of the US healthcare system. As the size of the elderly population grows, the number of fractures attributed to osteoporosis is expected to increase. Studies have shown that osteoporotic patients are at an increased risk for medical and surgical complications. The purpose of this study was to evaluate the association between sex and the incidence of postoperative mortality in the peri-operative period following surgical intervention for OVCF.

METHODS

A retrospective analysis of the American College of Surgeons National Surgery Quality Improvement Project (ACS-NSQIP) database from 2007 to 2014 identified 1979 patients. Patients were grouped as male or female. Mortality within 30 days of surgery due to any cause, incidence of surgical complications, and 30-day readmission rates following surgery were tabulated. A multivariate logistic regression analysis was conducted to calculate odds ratios (OR) with corresponding p values and 95% confidence intervals.

RESULTS

In total, 1979 patients met inclusion and exclusion criteria. Mortality within the 30 days following surgery for OVCF was statistically greater in men than in women (OR = 1.58; p = 0.050). The 30-day readmission rate was also statistically higher in men (OR = 1.41; p = 0.017). Neither minor (OR = 0.90; p = 0.560) nor major (OR = 1.14; p = 0.569) complications were statistically correlated with sex. On average, men underwent surgery for OVCF at a younger age than women.

CONCLUSIONS

Male patients undergoing surgery for OVCF have higher rates of peri-operative mortality and 30-day readmissions following surgery. Sex was not found to be associated with postoperative complications.

LEVEL OF EVIDENCE

III.

Relationship between morphological and vascular alterations in geographic atrophy using a multimodal imaging approach

PURPOSE

To assess geographic atrophy (GA) using a multimodal imaging approach, focusing on alterations at the level of the retinal pigment epithelium (RPE) and the choriocapillaris (CC) layers, by lesion demarcation, and assessment of morphological alterations within the atrophic area and in the transition zone.

METHODS

Fifty-seven eyes of 34 patients with atrophic age-related macular degeneration (AMD) were included in this prospective, observational, cross-sectional study. Multimodal imaging using wide-field polarization-sensitive optical coherence tomography (PS-OCT), optical coherence tomography angiography (OCT-A) and fundus autofluorescence (FAF) was performed. The images were overlaid and used to analyse and compare alterations in the retina and the CC.

RESULTS

Mean atrophic lesion size was 8.15 mm² (range: 2.23-17.23 mm² ). In 52 of 57 eyes (91%), OCT-A displayed focal hypodense areas at the CC level in the transition zone of GA, as well as increased focal depolarizing material (e.g. melanin-containing structures) showed in PS-OCT en face depolarizing material maps. These regions of increased depolarizing material at the transition zone corresponded to the hypodense areas on OCT-A scans. All 57 eyes presented with abnormal FAF patterns at the transition zone. All 57 eyes showed distinct alterations of CC flow pattern architecture. Six eyes (11%) demonstrated reduced and three eyes (5%) a complete loss of CC flow pattern architecture across the entire area of GA, while 48 of 57 eyes (84%) presented with irregular mixed patterns of different focal alterations of CC flow architecture within the area of GA. Reduced CC patterns exceeding GA lesion margins into the transitional zone were found in all eyes.

CONCLUSIONS

Optical coherence tomography angiography images revealed different degrees of flow impairment within the atrophic lesion area and its transition zone. Alterations in RPE morphology and tissue integrity resulting in accumulation of depolarizing material, such as melanin, could result in misinterpretation of OCT-A imaging in areas in the shadow of depolarizing material. These changes seem to be partially independent from autofluorescence altering processes.

Repeatability and reliability of quantitative fundus autofluorescence imaging in patients with early and intermediate age-related macular degeneration

PURPOSE

Quantification of fundus autofluorescence has only recently become available. We report our findings on the evaluation of the repeatability and reliability of quantitative fundus autofluorescence (qAF) measurements in patients with early and intermediate age-related macular degeneration (AMD), using the first approved and commercially available instrument.

METHODS

A total of 43 eyes of 22 patients (aged between 52 and 84 years) diagnosed with early and intermediate AMD were included. All eyes were imaged at day 1, 3 months and 6 months using a modified scanning laser ophthalmoscope, equipped with an internal fluorescent reference. Mean qAF values were calculated for the fovea and for each concentric ring of the Delori pattern. Repeatability and reliability were calculated using Bland-Altman analysis and intraclass correlation (ICC).

RESULTS

The mean patient age was 73.5 ± 7.9 years. Sixteen patients (73%) were female. qAF repeatability of the eight segments in the middle ring of the Delori pattern (qAF_{M 8} ) for between sessions was ±8.2%. Agreement at 3- and 6-month follow-up in eyes without retinal changes was ±8.3% and ±9.8%, respectively. Reliability of qAF_{M 8} was high for all images acquired [ICC = 0.98 (CI: 0.96-0.99), 0.97 (0.93-0.99) and 0.98 (0.92-0.99)]. Agreement at 3- and 6-month follow-up in eyes with retinal changes was ±18.1% and ±20.2%, respectively. Intraclass correlation (ICC) was slightly lower in eyes with retinal changes at 0.93 (0.84-0.97) and 0.96 (0.91-0.98), respectively.

CONCLUSIONS

Quantitative autofluorescence shows excellent repeatability and reliability as well as follow-up agreement in patients with early and intermediate AMD without retinal changes. This is relevant when conducting longitudinal studies using qAF.

Comparison of SD-Optical Coherence Tomography Angiography and Indocyanine Green Angiography in Type 1 and 2 Neovascular Age-related Macular Degeneration

Purpose

The purpose of this study is to compare the ability of spectral domain optical coherence tomography angiography (SD-OCTA) and indocyanine green angiography (ICGA) to detect and measure lesion area in patients with type 1 and 2 choroidal neovascularization (CNV).

Methods

Types 1 and 2 neovascular AMD (nAMD) were included in this prospective and observational case series. ETDRS best-corrected visual acuity (BCVA), ophthalmic examination with funduscopy, OCTA (AngioVue), fluorescein angiography (FA), ICGA, and OCT (Spectralis) were performed. CNV measurements were done manually by two experienced graders using the systems' innate region selection tools.

Results

Forty eyes of 39 consecutive patients with nAMD were included. Mean age was 77 ± 6.4 years, ETDRS BCVA was 67 ± 13 letters, and 11 eyes were treatment naïve. Nineteen CNV lesions were classified as type 1 and 21 as type 2. ICGA was able to identify CNV in all eyes. By contrast, OCTA detected CNV in 95% of type 1 and 86% of type 2 nAMD eyes. Mean overall CNV area (CNV-A) was 2.8 ± 2.7 mm2 in ICGA and 2.1 ± 2.7 mm2 in OCTA. Both lesion types CNV-A appeared significantly smaller in OCTA compared with ICGA (P < 0.01). Bland-Altman plot revealed a mean difference (bias) between OCTA and ICGA CNV-A of 0.76 ± 1.74 mm2. Intraclass correlation coefficient (ICC) for CNV-A was 0.91 and 0.93 for ICGA and OCTA, respectively. ICGA CNV-A in the four OCTA-negative eyes (median 4.7 mm2) was not significantly different from the 36 OCTA-positive eyes (median 1.7 mm2).

Conclusions

Type 1 and 2 CNV-A were significantly smaller in OCTA than in ICGA. OCTA was generally less successful in detecting CNV than ICGA in patients who were included into this study based on FA and OCT. However, OCTA detected all type 1 lesions except for one, indicating that the SD-OCTA signal is limited by detection limits of blood flow velocity rather than lesion type. Further efforts are needed pushing the limits of lowest detectable and fastest distinguishable flow until OCTA can deliver realistic qualitative and quantitative imaging of type 1 and 2 CNV for diagnosis and monitoring.

[Geriatric Proximal Femoral Fracture and Urinary Tract Infection - Considerations for Perioperative Infection Prophylaxis]

Background: Perioperative infection prophylaxis with cephalosporins is standard in surgical treatment of proximal femoral fractures (PFF). Geriatric patients (pat.) are at risk of chronic infections and the bacteria from these can lead to unknown hygienic problems in an early operation. We therefore characterised the colonisation of the urinary tract in pat. (≥ 65 years) with PFF and observed bacterial development in deep wound infections over a period of 10 years. The aim was to discover gaps in perioperative infection prophylaxis. Patients and Methods: Between September 2013 and November 2015, colonisation of the urinary tract and microbial resistance were investigated on admission of all pat. (≥ 65 years) with the diagnosis of PFF (n = 351; f/m 263/88; median age [∅] 83.57 [65-100] years). Between 2005 and 2014, 2161 pat. with a PFF were operated in our clinic (f/m 1623/538; ∅ 82.35 [65-101] years). 991 pat. (∅ 81.84 [65-101] years) with femoral neck fracture [FNF] were treated with endoprosthesis/osteosynthesis, 1170 pat. (∅ 82,78 [65-101] years) with per-/subtrochanteric fracture [PTF] were treated with osteosynthesis. In a retrospective data analysis, deep wound infections, microbiological composition and changes in microbial resistances over time were identified. Results: Bacteriuria (BU) was detected in the urine sediment of 35.61 % (n = 125) of our pat. In 47.2 % of these pat., BU was accompanied by laboratory signs of manifest urinary tract infection. In 10.4 % of these pat., colonisation of the urinary tract with multi-resistant pathogens was detected; 26.4 % were resistant to cefuroxime. The rate of deep infections in pat. with endoprosthesis/osteosynthesis in FNF was 2.8 % (n = 28; f/m 19/9; ∅ 81.35 [67-92] years), with osteosynthesis in PTF 1,1 % (n = 14; f/m 10/4; ∅ 81.0 [70-91] years). A comparison of the periods 2005-2009 and 2010-2014 showed a shift in the spectrum of pathogens from cephalosporin-sensitive to cephalosporin-resistant enterococci. Resistance of pathogens against cephalosporins increased from 43 to 81 %. Conclusion: We found an increasing risk in geriatric pat. from multiresistant pathogens in the urinary tract and from an increase in the cephalosporin resistance of pathogens in urinary tract infections and in deep wound infections. This indicates that perioperative infection prophylaxis with a cephalosporin is not effective. Especially in nursing homes, development of resistance to antibiotics is an increasing problem. Thus, concepts of perioperative infection prophylaxis in geriatric patients should be reconsidered.

[Intramedullary Stabilisation of Displaced Midshaft Clavicular Fractures in Heavy Workers and Complex Fracture Pattern]

BACKGROUND

The medical literature recommends plate osteosynthesis (PO) for complex displaced midshaft clavicular fractures (DMCF) OTA type 15B3 and for heavy workers with displaced clavicular fractures. Recovery of DMCF treated with intramedullary stabilisation (IMS) will be examined and compared to published data for duration of inability to work (DIW) after conservative treatment as well as after PO, with respect to the DIW.

PATIENTS AND METHODS

Between 09/2009 and 07/2015, the DIW of 58 patients (8 f, 50 m, mean age 38.4 [20-59] years) with DMCF treated with open reduction and IMS (Titanium Elastic Nail [TEN], Synthes, Umkirch, Germany) was determined. Inclusion criteria were the presence of closed unilateral DMCF and presence of a job with national insurance at the time of accident. DIW was counted in days, starting with the accident, and ending on the last day before resumption of full work. All patients were functionally treated for 6 weeks postoperatively without weights for the shoulder and with a maximum of 90° abduction/flexion. The workload was classified in accordance with REFA criteria: group 0-1 (low physical workload) and group 2-4 (high physical workload). Fracture patterns (simple vs. complex) and postoperative physiotherapy (yes vs. no) were investigated for both REFA groups, as these factors may influence DIW. Fracture classification was performed in accordance with the OTA classification, as simple fractures (OTA type 15B1 and 15B2), and complex fractures (OTA type 15B3). Effects were concerned significant if p ≤ 0.05.

RESULTS

Median DIW was independent of physical workload, with 39.86 (3-150) days (n = 58). Patients with low physical workload (REFA 0-1; n = 33) had shorter duration of DIW, with an average of 32.48 (3-136) days than patients with higher physical workload (REFA 2-4; n = 25), with 49.6 (14-150) days (p = 0.02). The fracture type did not influence this significantly (simple fractures [n = 35]: average 40.54 [3-150] days; complex fractures [n = 23]: average 38.82 [14-136] days, p = 0.85). Within each REFA group, differences in DIW for each fracture type were greater, but did not attain statistical significance. Patients without postoperative PT (n = 30) had a shorter DIW, with an average of 30.5 (3-84) days, than patients with postoperative PT (n = 28), with an average of 49.89 (14-150) days (p = 0.021). Within both REFA groups, DIW changed similarly with postoperative PT, in some cases with statistical significance.

CONCLUSION

DIW after IMS of DMCF does not depend on the complexity of the fracture. For heavy workers, DIW after IMS is significantly longer than for light physical workers. IMS of DMCF permits immediate pain-adapted movement of the shoulder, with a maximal abduction/flexion up to 90°, no matter what the fracture type. Patients given additional professional PT showed longer DIW than those without such treatment.

Choroidal Line Scan Measurements in Swept-Source Optical Coherence Tomography as Surrogates for Volumetric Thickness Assessment

PURPOSE

To compare choroidal thickness of different areas on swept-source optical coherence tomography (SSOCT) line and cube scans for their interchangeable use.

DESIGN

Validity analysis.

METHODS

SSOCT line and cube scans were obtained from 21 patients with various choroidal thicknesses. Subfoveal center point choroidal thickness, mean central millimeter choroidal thickness, and mean 6-mm-area choroidal thicknesses were obtained from both eyes by 2 independent graders in a reading center setting. Cross-correlations were performed using Passing and Bablok regression models. A 95% confidence interval of slope that included 1 was considered to indicate no significant difference. Average choroidal thickness of center point, Early Treatment Diabetic Retinopathy Study grid subfields, and total grid area of 6 mm on both scans and the correlation between different areas served as main outcome measures.

RESULTS

No significant difference between line scans/corresponding subfields of cube scans (outer nasal 0.92-1.11, inner nasal 0.88-1.06, central 0.94-1.11, inner temporal 0.95-1.12, outer temporal 0.93-1.17). No significant difference between subfoveal center point measurement/mean of choroidal thickness in the central millimeter of cube scans (0.89-1.08). Significant difference of subfoveal center point measurement or mean of central millimeter area of cube scans to entire 6-mm area of cube scans (1.01-1.53 and 1.03-1.38).

CONCLUSIONS

Measurements on a single SSOCT horizontal line scan can represent the entire choroid but subfoveal center point measurements are only indicative for the central millimeter area. There is a consistent overestimation of choroidal thickness when trying to estimate overall choroidal thickness from any central measurement.

Prognostic value and therapeutic potential of TREM-1 in Streptococcus pyogenes- induced sepsis

TREM-1 (triggering receptor expressed on myeloid cells) is a surface molecule expressed on neutrophils and macrophages which has been implicated in the amplification of inflammatory responses triggered during infection. In the present study, we have investigated the clinical significance of TREM-1 in Streptococcus pyogenes-induced severe sepsis in both experimentally infected mice as well as in patients with streptococcal toxic shock. We found that S. pyogenes induced a dose-dependent upregulation of TREM-1 in in vitro cultured phagocytic cells and in the organs of S. pyogenes-infected mice. Furthermore, we reported a positive correlation between serum levels of soluble TREM-1 (sTREM-1) and disease severity in infected patients as well as in experimentally infected mice. Hence, sTREM-1 may represent a useful surrogate marker for streptococcal sepsis. We found that modulation of TREM-1 by administration of the TREM-1 decoy receptor rTREM-1/Fc substantially attenuated the synthesis of inflammatory cytokines. More importantly, treatment of S. pyogenes-infected septic mice with rTREM-1/Fc or the synthetically produced conserved extracellular domain LP17 significantly improved disease outcome. In summary, our data suggest that TREM-1 may not only represent a valuable marker for S. pyogenes infection severity but it may also be an attractive target for the treatment of streptococcal sepsis.

Intracellular Streptococcus pyogenes in human macrophages display an altered gene expression profile

Streptococcus pyogenes is an important human pathogen, which has recently gained recognition as an intracellular microorganism during the course of severe invasive infections such as necrotizing fasciitis. Although the surface anchored M protein has been identified as a pivotal factor affecting phagosomal maturation and S. pyogenes survival within macrophages, the overall transcriptional profile required for the pathogen to adapt and persist intracellularly is as of yet unknown. To address this, the gene expression profile of S. pyogenes within human macrophages was determined and compared to that of extracellular bacteria using customized microarrays and real-time qRT-PCR. In order to model the early phase of infection involving adaptation to the intracellular compartment, samples were collected 2h post-infection. Microarray analysis revealed that the expression of 145 streptococcal genes was significantly altered in the intracellular environment. The majority of differentially regulated genes were associated with metabolic and energy-dependent processes. Key up-regulated genes in early phase intracellular bacteria were ihk and irr, encoding a two-component gene regulatory system (TCS). Comparison of gene expression of selected genes at 2h and 6h post-infection revealed a dramatic shift in response regulators over time with a down-regulation of ihk/irr genes concurring with an up-regulation of the covR/S TCS. In re-infection assays, intracellular bacteria from the 6h time point exhibited significantly greater survival within macrophages than did bacteria collected at the 2h time point. An isogenic S. pyogenes mutant deficient in ihk/irr displayed significantly reduced bacterial counts when compared to wild-type bacteria following infection of macrophages. The findings illustrate how gene expression of S. pyogenes during the intracellular life cycle is fine-tuned by temporal expression of specific two-component systems.

International round-robin study on the Ames fluctuation test

An international round-robin study on the Ames fluctuation test [ISO 11350, 2012], a microplate version of the classic plate-incorporation method for the detection of mutagenicity in water, wastewater and chemicals was performed by 18 laboratories from seven countries. Such a round-robin study is a precondition for both the finalization of the ISO standardization process and a possible regulatory implementation in water legislation. The laboratories tested four water samples (spiked/nonspiked) and two chemical mixtures with and without supplementation of a S9-mix. Validity criteria (acceptable spontaneous and positive control-induced mutation counts) were fulfilled by 92-100%, depending on the test conditions. A two-step method for statistical evaluation of the test results is proposed and assessed in terms of specificity and sensitivity. The data were first subjected to powerful analysis of variance (ANOVA) after an arcsine-square-root transformation to detect significant differences between the test samples and the negative control (NC). A threshold (TH) value based on a pooled NC was then calculated to exclude false positive test results. Statistically, positive effects observed by the William's test were considered negative, if the mean of all replicates of a sample did not exceed the calculated TH. By making use of this approach, the overall test sensitivity was 100%, and the test specificity ranged from 80 to 100%.

Inducible cyclooxygenase released prostaglandin E2 modulates the severity of infection caused by Streptococcus pyogenes

Streptococcus pyogenes is a significant human pathogen that can cause life-threatening invasive infections. Understanding the mechanism of disease is crucial to the development of more effective therapies. In this report, we explored the role of PGE(2), an arachidonic acid metabolite, and its rate-limiting enzyme cyclooxygenase 2 (COX-2) in the pathogenesis of severe S. pyogenes infections. We found that the COX-2 expression levels in tissue biopsies from S. pyogenes-infected patients, as well as in tissue of experimentally infected mice, strongly correlated with the severity of infection. This harmful effect was attributed to PGE(2)-mediated suppression of the bactericidial activity of macrophages through interaction with the G2-coupled E prostanoid receptor. The suppressive effect of PGE(2) was associated with enhanced intracellular cAMP production and was mimicked by the cAMP-elevating agent, forskolin. Activation of protein kinase A (PKA) was the downstream effector mechanisms of cAMP because treatment with PKI(14-22), a highly specific inhibitor of PKA, prevented the PGE(2)-mediated inhibition of S. pyogenes killing in macrophages. The inhibitory effect exerted by PKA in the generation of antimicrobial oxygen radical species seems to be the ultimate effector mechanism responsible for the PGE(2)-mediated downregulation of the macrophage bactericidal activity. Importantly, either genetic ablation of COX-2, pharmacological inhibition of COX-2 or treatment with the G2-coupled E prostanoid antagonist, AH6809, significantly improved the disease outcome in S. pyogenes infected mice. Therefore, the results of this study open up new perspectives on potential molecular pathways that are prone to pharmacological manipulation during severe streptococcal infections.

From chiral vibration to static chirality in (135)Nd

Electromagnetic transition probabilities have been measured for the intraband and interband transitions in the two sequences in the nucleus (135)Nd that were previously identified as a composite chiral pair of rotational bands. The chiral character of the bands is affirmed and it is shown that their behavior is associated with a transition from a vibrational into a static chiral regime.

Primary mouse hepatocytes for systems biology approaches: a standardized in vitro system for modelling of signal transduction pathways

Complex cellular networks regulate regeneration, detoxification and differentiation of hepatocytes. By combining experimental data with mathematical modelling, systems biology holds great promises to elucidate the key regulatory mechanisms involved and predict targets for efficient intervention. For the generation of high-quality quantitative data suitable for mathematical modelling a standardised in vitro system is essential. Therefore the authors developed standard operating procedures for the preparation and cultivation of primary mouse hepatocytes. To reliably monitor the dynamic induction of signalling pathways, the authors established starvation conditions and evaluated the extent of starvation-associated stress by quantifying several metabolic functions of cultured primary hepatocytes, namely activities of glutathione-S-transferase, glutamine synthetase, CYP3A as well as secretion of lactate and urea into the culture medium. Establishment of constant metabolic activities after an initial decrease compared with freshly isolated hepatocytes showed that the cultured hepatocytes achieve a new equilibrium state that was not affected by our starving conditions. To verify the highly reproducible dynamic activation of signalling pathways in the in vitro system, the authors examined the JAK-STAT, SMAD, PI3 kinase, MAP kinase, NF-kappaB and Wnt/beta-catenin signalling pathways. For the induction of gp130, JAK1 and STAT3 phosphorylation IL6 was used, whereas TGFbeta was applied to activate the phosphorylation of SMAD1, SMAD2 and SMAD3. Both Akt/PKB and ERK1/2 phosphorylation were stimulated by the addition of hepatocyte growth factor. The time-dependent induction of a pool of signalling competent beta-catenin was monitored in response to the inhibition of GSK3beta. To analyse whether phosphorylation is actually leading to transcriptional responses, luciferase reporter gene constructs driven by multiple copies of TGFbeta-responsive motives were applied, demonstrating a dose-dependent increase in luciferase activity. Moreover, the induction of apoptosis by the TNF-like cytokine Fas ligand was studied in the in vitro system. Thus, the mouse hepatocyte in vitro system provides an important basis for the generation of high-quality quantitative data under standardised cell culture conditions that is essential to elucidate critical hepatocellular functions by the systems biology approach.

Calcium, carbonic anhydrase and gastric acid secretion

Previous data concerning the action of calcium (Ca) on gastric acid secretion (GAS) indicated that calcium ions increase GAS elicited by gastrin released through a vagal mechanism, and also by a direct effect on parietal cells. Our research showed that the stimulating effect of calcium on gastric acid secretion can be antagonized by verapamil administration, which reduces gastric acid secretion . In the present study we followed the effect induced by administration of calcium and Ca-chelating agents (disodium EDTA) on gastric acid secretion and on carbonic anhydrase (CA) activity. We selected two groups of healthy volunteers: Group I (n=21) received a single i.v. dose of CaCl2 (15 mg/kg b.w.), whereas Group II (n=22) received a single i.v. dose of disodium EDTA (5 mg/kg b.w.). We determined blood calcium before and after treatment, gastric acid secretion at 2 hours. erythrocyte CA II activity, and CA IV activity in membrane parietal cells, which were isolated from gastric mucosa obtained by endoscopic biopsy. Assessment of carbonic anhydrase activity was achieved by the stopped-flow method. In Group I calcium administration increased blood calcium, HCl output, CA II and CA IV activity as compared to initial values. In Group II, disodium EDTA reduced blood calcium, HCl output, CA II and CA IV activity as compared to initial values. The results demonstrated that increased blood calcium and GAS values after calcium administration correlated with the increase of erythrocyte CA II and parietal cell CA IV activity, while disodium EDTA induced a reversed process. Our results also show that cytosolic CA II and membrane CA IV values are sensitive to calcium changes and they directly depend on these levels. Our data suggest that intra- and extracellular pH changes induced by carbonic anhydrase might account for the modulation of the physiological and pathological secretory processes in the organism.

Vasoconstrictive drugs increase carbonic anhydrase I in vascular smooth muscle while vasodilating drugs reduce the activity of this isozyme by a direct mechanism of action

Carbonic anhydrase (CA) is a zinc enzyme that catalyses the reversible hydration reaction of CO2 and plays a major role in the acid-base balance. We have previously shown that certain vasoconstrictive therapeutic agents increase CA I activity whereas vasodilating drugs reduce the activity of this isozyme by a direct mechanism of action. In this paper we studied the effect of other vasoconstrictive and vasodilating agents on CA I activity in order to elucidate the involvement of vascular smooth muscle CA I in vasoconstrictive and vasodilating processes. We studied the in vitro effects of noradrenaline, prostaglandin F2 alpha, thromboxane A2, leukotriene B4, angiotensin II, vasopressin, indomethacin, prazosin, hydralazine, clonidine, reserpine, prostaglandin I2, indapamide, furosemide, amlodipine, verapamil and irbesartan on purified human red blood cell CA I and vascular smooth muscle CA I isolated from rabbits. In vivo, we selected six groups of five rabbits each, which were administered the following substances in acute experiments: orciprenaline (group 1), desmopressin (group 2), verapamil (group 3), irbesartan (group 4), acetazolamide (group 5) and placebo (control group). Vascular smooth muscle CA I activity and systolic blood pressure were determined and compared with those of the control group. In vitro results showed that all the vasoconstrictive agents studied increased purified and human erythrocyte CA I activity as well as vascular smooth muscle CA I, while vasodilating substances reduced the activity of isozyme by a direct mechanism of action. The same results obtained in vivo showed that activation of vascular smooth muscle CA I increased blood pressure while its inhibition reduced blood pressure. The results of this study suggest that pHi changes, induced by activating or inhibiting CA I in vascular smooth muscle, might be responsible for changes in vascular tonus.

Indomethacin activates carbonic anhydrase and antagonizes the effect of the specific carbonic anhydrase inhibitor acetazolamide, by a direct mechanism of action

OBJECTIVES

In this paper we investigated the effect of indomethacin, acetazolamide and their combination in vitro and in vivo on carbonic anhydrase (CA) isozymes.

METHOD

In vitro experiments followed the effect of the two substances at concentrations between 10(-8)-10(-4) M on purified human red cell CA I and II as well as on human gastric mucosa CA IV using dose-response relationships. Kinetic studies were also performed. The effects of single and combined administration of indomethacin and acetazolamide on red cell CA and on gastric acid secretion were studied in vivo.

RESULTS

Indomethacin, in vitro and in vivo. induces an increase in erythorcyte CA I and CA II activity. Acetazolamide, a specific inhibitor of CA, reduces the activity of CA I and CA II from red cells. Indomethacin completely antagonizes CA activity, i.e. abolishes the inhibitory effect of acetazolamide on CA. In humans, an increase or decrease in erythrocyte CA II activity is correlated with an increase or decrease in gastric acid secretion.

CONCLUSIONS

Our results show that indomethacin, a known cyclooxygenase (COX) inhibitor, is also an activator of CA. Our data also prove that indomethacin is not only an activator of CA but also antagonizes the effect of acetazolamide, a specific inhibitor of this enzyme. In view of the role of CA in acid-base balance as well as the fact that an increase or decrease in its activity is accompanied by an increase or decrease in intra- and extracellular pH, our results suggest that: firstly, CA activation induced by indomethacin might cause changes in COX activity; secondly, PGs are synthetized as a consequence of the changes in COX activity, a hypothesis that requires further study.

The mechanism of action of angiotensin II is dependent on direct activation of vascular smooth muscle carbonic anhydrase I

Our previous studies have shown that angiotensin II increases carbonic anhydrase activity both in vitro and in vivo. In this study we investigated in vitro the effect of angiotensin II on carbonic anhydrase I and II from erythrocytes and on arteriolar vascular smooth muscle carbonic anhydrase I. We also studied in vitro and in vivo the effect of angiotensin II receptor blockers (irbesartan and candesartan) on purified carbonic anhydrase I and II, on vascular smooth muscle carbonic anhydrase I and on arterial blood pressure in humans and in animals. In vitro results showed that angiotensin II is a direct and stronger activator of carbonic anhydrase I than II. Angiotensin II receptor blockers reduced mainly carbonic anhydrase I activity and completely antagonized the activating effect of angiotensin II both on purified and on vascular smooth muscle carbonic anhydrase I. Our in vivo experiments showed that irbesartan and candesartan are powerful inhibitors of carbonic anhydrase I both in erythrocytes (in humans) and in vascular smooth muscles (in animals). In humans, irbesartan and candesartan progressively reduce arterial blood pressure in hypertensive subjects, in parallel with progressive reduction of erythrocyte carbonic anhydrase I activity. We believe that angiotensin II could have a dual mechanism of action: (1) angiotensin interacting with its receptor to form a stimulus-receptor complex; (2) the same stimulus directly acts on the carbonic anhydrase I isozyme (which might be coupled with angiotensin II receptors), ensuring an adequate pH for stimulus-receptor coupling for signal transmission into the cell and hence vasoconstriction.

Catecholamine-induced vasoconstriction is sensitive to carbonic anhydrase I activation

We studied the relationship between alpha- and beta-adrenergic agonists and the activity of carbonic anhydrase I and II in erythrocyte, clinical and vessel studies. Kinetic studies were performed. Adrenergic agonists increased erythrocyte carbonic anhydrase as follows: adrenaline by 75%, noradrenaline by 68%, isoprenaline by 55%, and orciprenaline by 62%. The kinetic data indicated a non-competitive mechanism of action. In clinical studies carbonic anhydrase I from erythrocytes increased by 87% after noradrenaline administration, by 71% after orciprenaline and by 82% after isoprenaline. The increase in carbonic anhydrase I paralleled the increase in blood pressure. Similar results were obtained in vessel studies on piglet vascular smooth muscle. We believe that adrenergic agonists may have a dual mechanism of action: the first one consists of a catecholamine action on its receptor with the formation of a stimulus-receptor complex. The second mechanism proposed completes the first one. By this second component of the mechanism, the same stimulus directly acts on the carbonic anhydrase I isozyme (that might be functionally coupled with adrenergic receptors), so that its activation ensures an adequate pH for stimulus-receptor coupling for signal transduction into the cell, resulting in vasoconstriction.

Hypotensive effect of calcium channel blockers is parallel with carbonic anhydrase I inhibition

In this article we studied in vitro and in vivo the effect of calcium channel blockers (verapamil and amlodipine) on erythrocyte carbonic anhydrase I activity, on carbonic anhydrase I isolated from vascular smooth muscles, and on arterial blood pressure values in human beings and in animals. Our in vitro and in vivo results have shown that verapamil and amlodipine are strong inhibitors of carbonic anhydrase I both in erythrocytes (in human beings) and in vascular smooth muscles (in animals). In human beings calcium channel blockers reduce arterial blood pressure in subjects with hypertension and progressively reduce erythrocyte carbonic anhydrase I activity. We assume that verapamil and amlodipine possess a dual mechanism of action: the first mechanism consists of their action on calcium channels, and the second mechanism, proposed by us, shows that verapamil and amlodipine inhibit vascular smooth muscle carbonic anhydrase I activity with consecutive pH increase. The increase of pH might be an additional factor involved in intracellular calcium influx through calcium channels. This dual mechanism of action would bring new data regarding the hypotensive effect of verapamil and amlodipine, effects that might also be parallel and dependent on carbonic anhydrase I inhibition.

Calcium channel blockers reduce blood pressure in part by inhibiting vascular smooth muscle carbonic anhydrase I

Calcium channel blockers are a group of drugs used for the treatment of hypertension. Carbonic anhydrase (CA) I detected in vascular smooth muscle and in other cells in the organism has a major role in the acid-base balance and in vascular processes. Our previous work has proven that verapamil inhibits CA activity by a direct mechanism of action. Starting from our results in this article we studied in vitro and in vivo the effect of calcium channel blockers (verapamil and amlodipine) on erythrocyte CA I, on vascular smooth muscles CA I, and on arterial blood pressure values in human and in animals. Our in vitro and in vivo results have proved that verapamil and amlodipine are strong CA I inhibitors both in human erythrocytes and also in vascular smooth muscles in animals. In humans, calcium channel blockers studied here progressively reduce arterial blood pressure in hypertensive subjects, in parallel with progressive lowering of erythrocyte CA I activity in the normal range in normotensive subjects. From our point of view verapamil and amlodipine possess a dual mechanism of action: the first well-known action consists of their action on calcium channels. The second mechanism, suggested by us, directly acts on the vascular smooth muscle CA I isozyme, so that its inhibition should ensure an adequate pH for calcium ions transport through the channels, having as result vasodilation. This double mechanism could explain the hypotensive effect of verapamil and amlodipine, with a mechanism that partially dependent on CA I inhibition.

Curbing the nuclear activities of beta-catenin. Control over Wnt target gene expression

Wnt molecules control numerous developmental processes by altering specific gene expression patterns, and deregulation of Wnt signaling can lead to cancer. Many Wnt factors employ beta-catenin as a nuclear effector. Upon Wnt stimulation, beta-catenin heterodimerizes with T-cell factor (TCF) DNA-binding proteins to form a transcriptional activator complex. As the activating subunit of this complex, beta-catenin performs dual tasks: it alleviates repression of target gene promoters and subsequently it activates them. Beta-catenin orchestrates these effects by recruiting chromatin modifying cofactors and contacting components of the basal transcription machinery. Although beta-catenin and TCFs are universal activators in Wnt signaling, their target genes display distinct temporal and spatial expression patterns. Apparently, post-translational modifications modulate the interactions between TCFs and beta-catenin or DNA, and certain transcription factors can sequester beta-catenin from TCFs while others synergize with beta-catenin-TCF complexes in a promoter-specific manner. These mechanisms provide points of intersection with other signaling pathways, and contribute to the complexity and specificity of Wnt target gene regulation.

The p300/CBP acetyltransferases function as transcriptional coactivators of beta-catenin in vertebrates

Wnt growth factors regulate a variety of developmental processes by altering specific gene expression patterns. In vertebrates beta-catenin acts as transcriptional activator, which is needed to overcome target gene repression by Groucho/TLE proteins, and to permit promoter activation as the final consequence of Wnt signaling. However, the molecular mechanisms of transcriptional activation by beta-catenin are only poorly understood. Here we demonstrate that the closely related acetyltransferases p300 and CBP potentiate beta-catenin-mediated activation of the siamois promoter, a known Wnt target. beta-catenin and p300 also synergize to stimulate a synthetic reporter gene construct, whereas activation of the cyclin D1 promoter by beta-catenin is refractory to p300 stimulation. Axis formation and activation of the beta-catenin target genes siamois and Xnr-3 in Xenopus embryos are sensitive to the E1A oncoprotein, a known inhibitor of p300/CBP. The C-terminus of beta-catenin interacts directly with a region overlapping the CH-3 domain of p300. p300 could participate in alleviating promoter repression imposed by chromatin structure and in recruiting the basal transcription machinery to promoters of particular Wnt target genes.

Vasodilatory effect of diuretics is dependent on inhibition of vascular smooth muscle carbonic anhydrase by a direct mechanism of action

Five years ago, our in vitro and in vivo studies demonstrated for the first time that diuretic agents such as furosemide, hydrochlorothiazide, amiloride, triamterene and spironolactone inhibit carbonic anhydrase (CA) I, II and renal CA IV by a direct mechanism of action. In this paper we investigate the relationship between diuretics and CA I in the vasodilatory mechanism. Both in vitro (on purified CA I, erythrocyte CA I and smooth muscle CA I) and in vivo (in human and rabbits) we studied the effect of acetazolamide, hydrochlorothiazide, indapamide, furosemide, amiloride and triamterene on purified CA I, on human erythrocyte CA I, as well as on CA I isolated from vascular smooth muscle. Our results demonstrate that in vitro all diuretics inhibit CA I by a direct mechanism of action. Inhibition reached 100% with acetazolamide, 45% with hydrochlorothiazide, 82% with indapamide, 85% with furosemide, 68% with amiloride and 58% with triamterene. In vivo, similar inhibition of erythrocyte and smooth muscle CA I was obtained, being parallel with a reduction in arterial blood pressure values. Our data show that in addition to their already known mechanisms, diuretics also inhibit CA in vascular smooth muscle. Our results suggest that this mechanism is achieved by means of pH changes induced by CA I inhibition.

Functional characterization of multiple transactivating elements in beta-catenin, some of which interact with the TATA-binding protein in vitro

beta-Catenin, a member of the family of Armadillo repeat proteins, plays a dual role in cadherin-mediated cell adhesion and in signaling by Wnt growth factors. Upon Wnt stimulation beta-catenin undergoes nuclear translocation and serves as transcriptional coactivator of T cell factor DNA-binding proteins. Previously the transactivation potential of different portions of beta-catenin has been demonstrated, but the precise location of transactivating elements has not been established. Also, the mechanism of transactivation by beta-catenin and the molecular basis for functional differences between beta-catenin and the closely related proteins Armadillo and Plakoglobin are poorly understood. Here we have used a yeast system for the detailed characterization of the transactivation properties of beta-catenin. We show that its transactivation domains possess a modular structure, consist of multiple subelements that cover broad regions at its N and C termini, and extend considerably into the Armadillo repeat region. Compared with beta-catenin the N termini of Plakoglobin and Armadillo have different transactivation capacities that may explain their distinct signaling properties. Furthermore, transactivating elements of beta-catenin interact specifically and directly with the TATA-binding protein in vitro providing further evidence that a major function of beta-catenin during Wnt signaling is to recruit the basal transcription machinery to promoter regions of Wnt target genes.

The C-terminal transactivation domain of beta-catenin is necessary and sufficient for signaling by the LEF-1/beta-catenin complex in Xenopus laevis

Beta-catenin is a multifunctional protein involved in cell adhesion and communication. In response to signaling by Wnt growth factors, beta-catenin associates with nuclear TCF factors to activate target genes. A transactivation domain identified at the C-terminus of beta-catenin can stimulate expression of artificial reporter genes. However, the mechanism of target gene activation by TCF/beta-catenin complexes and the physiological relevance of the beta-catenin transactivation domain still remain unclear. Here we asked whether the beta-catenin transactivation domain can generate a Wnt-response in a complex biological system, namely axis formation during Xenopus laevis embryogenesis. We show that a chimeric transcription factor consisting of beta-catenin fused to the DNA-binding domain of LEF-1 induces a complete secondary dorsoanterior axis when expressed in Xenopus. A LEF-1-beta-catenin fusion lacking the C-terminal transactivation domain is impaired in signaling while fusion of just the beta-catenin transactivator to the DNA-binding domain of LEF-1 is sufficient for axis-induction. The latter fusion molecule is blocked by dominant negative LEF-1 but not by excess cadherin indicating that all events parallel or upstream of the transactivation step mediated by beta-catenin are dispensable for Wnt-signaling. Moreover, beta-catenin can be replaced by a heterologous transactivator. Apparently, the ultimate function of beta-catenin in Wnt signaling is to recruit the basal transcription machinery to promoter regions of specific target genes.

Nuclear endpoint of Wnt signaling: neoplastic transformation induced by transactivating lymphoid-enhancing factor 1

The interaction between beta-catenin and LEF-1/TCF transcription factors plays a pivotal role in the Wnt-1 signaling pathway. The level of beta-catenin is regulated by partner proteins, including glycogen synthase kinase-3beta (GSK-3beta) and the adenomatous polyposis coli (APC) tumor suppressor protein. Genetic defects in APC are responsible for a heritable predisposition to colon cancer. APC protein and GSK-3beta bind beta-catenin, retain it in the cytoplasm, and facilitate the proteolytic degradation of beta-catenin. Abrogation of this negative regulation allows beta-catenin to translocate to the nucleus and to form a transcriptional activator complex with the DNA-binding protein lymphoid-enhancing factor 1 (LEF-1). This complex is thought to be involved in tumorigenesis. Here we show that covalent linkage of LEF-1 to beta-catenin and to transcriptional activation domains derived from the estrogen receptor or the herpes simplex virus protein VP16 generates transcriptional regulators that induce oncogenic transformation of chicken embryo fibroblasts. The chimeras between LEF-1 and beta-catenin or VP16 are constitutively active, whereas fusions of LEF-1 to the estrogen receptor are regulatable by estrogen. These experiments document the oncogenicity of transactivating LEF-1 and show that the transactivation domain normally provided by beta-catenin can be replaced by heterologous activation domains. These results suggest that the transactivating function of the LEF-1/beta-catenin complex is critical for tumorigenesis and that this complex transforms cells by activating specific LEF-1 target genes.

CT diagnosis of acquired intercostal lung herniation

Intercostal lung herniation is a rare complication of trauma, best demonstrated by computed tomography. Most intercostal lung herniations are the result of direct trauma to the chest wall or occur at sites of prior percutaneously placed chest tubes. We present two cases of acquired intercostal lung herniation.

Regulation of sucrase and lactase in developing rats: role of nuclear factors that bind to two gene regulatory elements

BACKGROUND & AIMS

Sucrase-isomaltase and lactase-phlorizin hydrolase expressions change remarkably during postnatal development in rats. The aim of this study was to explore the role of transacting nuclear proteins, proteins that bind to the SIF1 cis-regulatory element of the sucrase-isomaltase gene and to the CE-LPH1 cis-regulatory element of the lactase-phlorizin hydrolase gene, in this regulation.

METHODS

Enzyme activity, Northern analysis, and electrophoretic mobility shift assays were used to study the relationship of these nuclear proteins to sucrase-isomaltase and lactase-phlorizin hydrolase gene expression in rats during development.

RESULTS

A rapidly migrating low-molecular-weight SIF1-binding protein was found in suckling animals without sucrase-isomaltase messenger RNA (mRNA), and a higher-molecular-weight-binding protein was found in older animals with expression of sucrase-isomaltase mRNA. Supershift experiments and Western analysis showed that neither protein is Cdx-2, the only previously described SIF1-binding protein. CE-LPH1-binding protein was found only in adult animals (with low lactase activity), and there was no relationship between enzymatic activity and levels of lactase-phlorizin hydrolase mRNA.

CONCLUSIONS

SIF1-binding proteins may regulate sucrase-isomaltase expression during postnatal development, but CE-LPH1-binding proteins do not seem to regulate lactase-phlorizin hydrolase expression during this period.

SIR2 and SIR4 interactions differ in core and extended telomeric heterochromatin in yeast

Yeast core telomeric heterochromatin can silence adjacent genes and requires RAP1, SIR2, SIR3, and SIR4 and histones H3 and H4 for this telomere position effect. SIR3 overproduction can extend the silenced domain. We examine here the nature of these multiprotein complexes. SIR2 and SIR4 were immunoprecipitated from whole-cell extracts. In addition, using formaldehyde cross-linking we have mapped SIR2, SIR4, and RAP1 along telomeric chromatin before and after SIR3 overexpression. Our data demonstrate that SIR2 and SIR4 interact in a protein complex and that SIR2, SIR3, SIR4, and RAP1 map to the same sites along telomeric heterochromatin in wild-type cells. However, when overexpressed, SIR3 spreads along the chromosome and its interactions are dominant to those of SIR4 and especially SIR2, whose detection is decreased in extended heterochromatin. RAP1 binding at the core region is unaffected by SIR3 overproduction and RAP1 shows no evidence of spreading. Thus, we propose that the structure of core telomeric heterochromatin differs from that extended by SIR3.

Spreading of transcriptional repressor SIR3 from telomeric heterochromatin

Telomeric genes and the HM loci in saccharomyces cerevisiae are transcriptionally repressed and adopt a heterochromatin-like structure. The trans-acting factors RAP1, SIR3 and SIR4 are required for telomeric and HM silencing, and are thought to be chromosomal, but how they contribute to histone-dependent repression of adjacent chromatin is unclear. SIR3 suppresses silencing defects in histones, is limiting for silencing adjacent to telomeres, and interacts with the H3 and H4 amino termini in vitro. Here we show that SIR3 co-immunoprecipitates SIR4, RAP1 and histones from cellular extracts, suggesting the presence of large chromatin-associated protein complexes. Crosslinking experiments show that SIR3 is present at HMRa, HMLalpha and telomeres in vivo, and that is spreads from telomeric regions into adjacent chromatin when overexpressed. Thus SIR3 is a structural component of yeast heterochromatin, repressing adjacent genes as it spreads along the chromosome.

Diagnosis and treatment of pneumonia in the nursing home

Risk factors, diagnosis, ethical considerations, and treatment of pneumonia in a nursing home setting are summarized. Risk factors for pneumonia include age-associated changes, co-morbid conditions, declining general health, and iatrogenic factors. Diagnosis can be challenging in geriatric residents because of atypical presentations and complex underlying diseases. Key features of presentation include rhonchi and confusion. An increased respiratory rate can be a sensitive indicator for pneumonia. Ethical dilemmas include identifying a resident's wishes for treatment in the event of an acute illness and the decision on whether to relocate the resident to an acute care facility. Decisions are based on available resources, medical stability of the resident, unimpeded access to a hospital, and the resident's well-informed decision. The common etiologic pathogen(s) of nursing-home-acquired pneumonia reflect a mixture between community-acquired and hospital-acquired pathogens. Multiple pharmacologic interventions are available, as well as supportive measures including oxygen therapy and hydration. Preventive measures are utilized to decrease the incidence of further infection.

Usefulness of increased myocardial cyclic adenosine 3',5'-monophosphate content as a sign of rejection after cardiac transplantation

Cardiac allograft rejection represents a series of cellular and molecular events triggered by the recognition of the graft by the host immune system. One of the second messenger systems involved in mitogenic mechanisms is the cyclic adenosine 3',5'-monophosphate (cAMP)-coupled signaling system. The aim of this preliminary study was to evaluate whether rejection after cardiac transplantation is accompanied by changes in the expression of cAMP. Myocardial cAMP content was determined by radioimmunoassay in endomyocardial biopsy specimens taken during routine follow-up after cardiac transplantation with or without cellular and/or vascular (i.e., coronary vasculopathy) rejection, respectively. Analysis of the different subgroups of patients showed that patients without any signs of rejection (no vasculopathy, no cellular rejection) had the lowest myocardial cAMP content (1.41 +/- 0.12 pmol/mg wet weight). Patients with either cellular or vascular rejection had significantly higher myocardial cAMP levels (2.25 +/- 0.29 and 2.24 +/- 0.59 pmol/mg wet weight, respectively, p < 0.05). Patients with both cellular rejection and coronary vasculopathy had the highest cAMP levels (5.95 +/- 1.6 pmol/mg wet weight; p < 0.001). We speculate that cAMP may play a functional role in mediating rejection induced by mitogenic factors activated after cardiac transplantation, suggesting a possible "cross-talk" between different cellular signaling pathways.

Histone H3 and H4 N-termini interact with SIR3 and SIR4 proteins: a molecular model for the formation of heterochromatin in yeast

The silent mating loci and chromosomal regions adjacent to telomeres of S. cerevisiae have features similar to heterochromatin of more complex eukaryotes. Transcriptional repression at these sites depends on the silent information regulators SIR3 and SIR4 as well as histones H3 and H4. We show here that the SIR3 and SIR4 proteins interact with specific silencing domains of the H3 and H4 N-termini in vitro. Certain mutations in these factors, which affect their silencing functions in vivo, also disrupt their interactions in vitro. Immunofluorescence studies with antibodies against RAP1 and SIR3 demonstrate that the H3 and H4 N-termini are required for the association of SIR3 with telomeric chromatin and the perinuclear positioning of yeast telomeres. Based on these interactions, we propose a model for heterochromatin-mediated transcriptional silencing in yeast, which may serve as a paradigm for other eukaryotic organisms as well.

The regulation of euchromatin and heterochromatin by histones in yeast

Yeast chromosomes may lack the linker histone H1 (normally required to compact 10 nm beads-on-a-string fiber into the 30 nm fiber) and there is no cytological evidence for higher order fiber structure but they do contain regions which correspond to euchromatin and heterochromatin of higher eukaryotes. Both euchromatin and heterochromatin contain nucleosomal particles (composed of two molecules each of H2A, H2B, H3 and H4), however histones have been shown to regulate genes in these regions in quite different ways. The mechanisms by which such regulation occurs are the topic of this paper.