Role of ultrasound in detection of lymph nodes metastasis in gynecological cancers: systematic review and meta-analysis

OBJECTIVE

To assess the diagnostic performance of transvaginal ultrasound (TVUS) for preoperative evaluation of lymph node metastasis in gynecological cancers.

METHODS

A systematic review and meta-analysis was performed. All studies published between January 1990 to May 2023 evaluating the role of ultrasound for detecting lymph node metastasis (index test) in gynecological cancers, using histopathological analysis, as reference standard were included. Quality was assessed using QUADAS-2. Pooled sensitivity, specificity and diagnostic odds ratio of TVUS were estimated.

RESULTS

The search identified 2638 citations. Eight studies comprising 967 women were included. The mean prevalence of pelvic lymph nodes metastasis was 24.2%, [14%-65.6%]. The risk of bias was low for most domains assessed. Overall pooled sensitivity, specificity and diagnostic odds ratio of TVUS were 41% (95% confidence interval [CI] =26%-58%), 98% (95%CI=93%-99%) and 32 (95%CI=14-72), respectively. Heterogeneity in TVUS evaluation was high between studies, both for sensitivity and specificity. No publication bias was found (p=0.46).

CONCLUSION

TVUS showed a high-pooled specificity for the detection of pelvic lymph node metastasis in gynecological cancers. However, pooled sensitivity was low. This article is protected by copyright. All rights reserved.

Engineering Organoids for in vitro Modeling of Phenylketonuria

Phenylketonuria is a recessive genetic disorder of amino-acid metabolism, where impaired phenylalanine hydroxylase function leads to the accumulation of neurotoxic phenylalanine levels in the brain. Severe cognitive and neuronal impairment are observed in untreated/late-diagnosed patients, and even early treated ones are not safe from life-long sequelae. Despite the wealth of knowledge acquired from available disease models, the chronic effect of Phenylketonuria in the brain is still poorly understood and the consequences to the aging brain remain an open question. Thus, there is the need for better predictive models, able to recapitulate specific mechanisms of this disease. Human induced pluripotent stem cells (hiPSCs), with their ability to differentiate and self-organize in multiple tissues, might provide a new exciting in vitro platform to model specific PKU-derived neuronal impairment. In this review, we gather what is known about the impact of phenylalanine in the brain of patients and highlight where hiPSC-derived organoids could contribute to the understanding of this disease.

Myriapod haemocyanin: the first three-dimensional reconstruction of Scolopendra subspinipes and preliminary structural analysis of S. viridicornis

Haemocyanins (Hcs) are copper-containing, respiratory proteins that occur in the haemolymph of many arthropod species. Here, we report the presence of Hcs in the chilopode Myriapoda, demonstrating that these proteins are more widespread among the Arthropoda than previously thought. The analysis of transcriptome of S. subspinipes subpinipes reveals the presence of two distinct subunits of Hc, where the signal peptide is present, and six of prophenoloxidase (PPO), where the signal peptide is absent, in the 75 kDa range. Size exclusion chromatography profiles indicate different quaternary organization for Hc of both species, which was corroborated by TEM analysis: S. viridicornis Hc is a 6 × 6-mer and S. subspinipes Hc is a 3 × 6-mer, which resembles the half-structure of the 6 × 6-mer but also includes the presence of phenoloxidases, since the 1 × 6-mer quaternary organization is commonly associated with hexamers of PPO. Studies with Chelicerata showed that PPO activity are exclusively associated with the Hcs. This study indicates that Scolopendra may have different proteins playing oxygen transport (Hc) and PO function, both following the hexameric oligomerization observed in Hcs.

Nutrient and organic matter removal from low strength sewage treated with constructed wetlands

The role of Eichhornia crassipes for removing pollutants from low strength sewage was evaluated in three pilot-scale constructed wetlands (CW): CW 1, planted with E. crassipes in a filter media; CW 2, unplanted, composed by filter media; and CW 3, composed by E. crassipes floating on the sewage. The operation was divided into three stages by varying the nominal hydraulic retention time into: (I) 24 h; (II) 48 h; (III) 72 h. Temporal sampling profiles were carried out with collection of the influent and effluent samples to determine temperature, pH, chemical oxygen demand (COD), TKN and TP. Contents of TP and TN were analyzed in the plant tissue of the macrophyte. The best removal efficiency rates for phosphorus (38%) and TKN (47%) were obtained in CW 3 for 72 h. The highest COD removal was observed in the CW 2 (80%) for 48 h. The macrophyte E. crassipes contributed to the absorption process with uptake rate percentages of 8.3% (CW 1) and 9.0% (CW 3) for TN and 0.78% (CW 1) and 1.56% (CW 3) for TP on the dry matter of the plant. The chosen species planted in the systems contributed to the achievement of higher nutrient removal.

Performance of different substrates in constructed wetlands planted with E. crassipes treating low-strength sewage under subtropical conditions

The present study aimed to assess removal potential of chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), total ammonia nitrogen (TAN), total phosphorus (TP) and acetylsalicylic acid (ASA) in synthetic wastewater simulating low-strength sewage by sequencing-batch mode constructed wetlands (CWs). Six CWs with three substrates (gravel, light expanded clay and clay bricks) and one CW of each substrate was planted with E. crassipes to verify the feasibility of using a floating macrophyte in CWs and verify the best optimized substrate. Results showed that the presence of E. crassipes enhanced the removal of COD for systems with gravel, increasing the removal efficiency from 37% in the unplanted system (CW_G-U) to 60% in the planted system (CW_G-P). The vegetated CW with clay bricks (CW_B-P) presented the best performance for both TKN and TAN removal, with maximum removal efficiencies of 68% and 35%, respectively. Phosphorus was observed to be efficiently removed in systems with clay bricks, both planted (CW_B-U) and unplanted (CW_B-P), with mean removal efficiencies of 82% and 87%, respectively, probably via adsorption. It was also observed that after 296days of operation, no desorption or increase on phosphorus in effluent samples were observed, thus indicating that the material was not yet saturated and phosphorus probably presents a strong binding to the media. ASA removal efficiency varied from 34% to 92% in CWs, probably due to plant uptake through roots and microbial biodegradation. Plant direct uptake varied from 4 to 74% of the total nitrogen and from 26 to 71% of the total phosphorus removed in CW_G-P, CW_C-P and CW_B-P. E. crassipes was able to uptake up to 4.19g of phosphorus in CW_C-P and 11.84g of nitrogen in CW_B-P. The findings on this study suggest that E. crassipes could be used in CWs and clay bricks could significantly enhance phosphorus removal capacity in CWs.

Carbon accumulation and storage capacity in mangrove sediments three decades after deforestation within a eutrophic bay

A dated sediment core from an eutrophic mangrove area presented non-significant differences in carbon accumulation rates before (55.7±10.2gm^-2yr^-1) and after three decades of deforestation (59.7±7.2gm^-2yr^-1). Although eutrophication effects appear to compensate the loss of mangrove organic matter input, the results in this work show a threefold lower carbon accumulation than the global averages estimated for mangrove sediments. The effects of increasing eutrophication and enhanced sediment dry bulk density observed after deforestation (~30% higher) did not result in higher carbon stocks. Moreover, the lower TOC:OP (<400) and C:N (~20) molar ratios, as well as increased nutrient accumulation, reflect the dominance of phytoplankton-derived organic matter after deforestation, resulting in less-efficient sedimentary carbon sinks. These results indicate that the organic material deposited from eutrophication may not compensate mangrove deforestation losses on carbon accumulation in mangrove ecosystems.

Increased expression of clp genes in Lactobacillus delbrueckii UFV H2b20 exposed to acid stress and bile salts

The ability to survive in harsh environments is an important criterion to select potential probiotics strains. The objective of this study was to identify and carry out phylogenetic and expression analysis by quantitative real-time PCR of the clpP, clpE, clpL and clpX genes in the probiotic strain Lactobacillus delbrueckii UFV H2b20 exposed to the conditions prevailing in the gastrointestinal tract (GIT). Phylogenetic trees reconstructed by Bayesian inference showed that the L. delbrueckii UFV H2b20 clpP, clpL and clpE genes and the ones from L. delbrueckii ATCC 11842 were grouped. The exposure of cells to MRS broth of pH 3.5 for 30 and 60 min resulted in an increased expression of the four genes. Exposure of the L. delbrueckii UFV H2b20 cells for 30 and 60 min to MRS broth containing 0.1% bile salts increased the expression of the clpP and clpE genes, while the expression level of the clpL and clpX genes increased only after 30 min of exposure. The involvement of the studied genes in the responses to acid stress and bile salts suggests a possible central role of these genes in the survival of L. delbrueckii UFV H2b20 during the passage through the GIT, a characteristic necessary for probiotic strains.

Intracoronary local paclitaxel delivery by X-ray contrast media for in-stent restenosis: a clinical pilot study to assess safety and tolerability

AIM

Non-stent-based immediate release formulations of paclitaxel have been shown to reduce in-stent restenosis in animal experiments and clinical trials. In the porcine overstretch model paclitaxel dissolved in the contrast medium iopromide inhibited neointimal proliferation in a dose-dependent manner after intracoronary injection and was well tolerated.

METHODS

As a first step entering clinical development, a phase I trial was performed using four ascending paclitaxel dose/concentration levels: samples of up to 100 mL of the contrast medium (iopromide) containing 10, 50, 100 or 200 µM paclitaxel or iopromide (controls) were randomly administered to patients assigned to bare metal stent implantation for single de novo coronary artery lesions. Safety variables, tolerability and angiographic parameters were assessed.

RESULTS

Adverse events, ECG, systolic and diastolic blood pressure, left ventricular ejection fraction, leukocyte count, other hematological or clinical chemistry data did not reveal any trend which could be related to the study medication. Short-lasting serum paclitaxel concentrations remained significantly below those known from cancer therapy. Angiographic late lumen loss was 0.72±0.50 mm (N.=7) in controls versus 0.45±0.65 mm (N.=17) in all paclitaxel-treated patients; binary restenosis rate was 5/7(63%) versus 6/17 (35%) and target lesion revascularization rate was 4/8 (50%) versus 4/24 (17%).

CONCLUSION

Intracoronary infusion of paclitaxel dissolved in an X-ray contrast medium was well tolerated. The results show restenosis inhibition, but the number of patients examined was too small to demonstrate a statistically significant inhibition.

Temporal and spatial dynamics of blocking and ripening effects on bacterial transport through a porous system: A possible explanation for CFT deviation

The studies on transport of particles across porous systems are based on the Colloid Filtration Theory (CFT). According to CFT, the collision efficiency is constant along the system length [J.N. Ryan, M. Elimelech, Colloids Surf. A: Physicochem. Eng. Aspects 107 (1996) 1-56]. Decreasing values of collision efficiency have been reported, a phenomenon that has been interpreted as a deviation from the CFT [X. Li, T.D. Scheibe, W.P. Johnson, Environ. Sci. Technol. 38 (2004) 5616-5625; N. Tufenkji, J.A. Redman, M. Elimelech, Environ. Sci. Technol. 37 (2003) 616-623; N. Tufenkji, M. Elimelech, Langmuir 20 (2004) 10818-10828; N. Tufenkji, M. Elimelech, Langmuir 21 (2005) 841-852]. This paper presents data on transport of Bacillus megaterium spores through quartz sand columns. The occurrence of consecutive phases of increase and decrease of the values of C/C(0), the effluent spore concentration expressed as a fraction of the influent spore concentration, is reported. These patterns of change in C/C(0) were interpreted as the result of the concomitant occurrence of blocking and ripening, the prevalence of these phenomena in different moments of the experiment, and the spatial distribution of the prevalence of blocking and ripening effects along the porous system. It is argued that this spatial distribution in the predominance of blocking and ripening, what leads to the intensification of ripening at the entrance of the porous system, might be a possible explanation for the reported deviation from the CFT for experimental conditions where ripening and blocking take place.

[Echocardiographic evaluation to select patients for cardiac resynchronization therapy]

Wide QRS complex and asynchronous myocardial contraction in heart failure are associated with poor prognosis. Resynchronization can be achieved by biventricular pacing (BVP), which leads to hemodynamic and clinical improvement and reverse remodeling, and may improve survival. However, there is a substantial subset of patients with wide QRS complexes in the electrocardiogram who does not improve despite BVP, and there are findings which suggest that resynchronization therapy may be also beneficial for heart failure patients with normal QRS duration. QRS width predicts the benefit of BVP only with limitation and only correlates weakly with echocardiographically determined myocardial asynchrony. Determination of asynchrony by tissue Doppler echocardiography seems to be the best predictor for improvement after BVP, although no consensus on the optimal method to assess asynchrony has yet been achieved. To date, most studies evaluating tissue Doppler echo in BVP were performed retrospectively and only one prospective study with patient selection for BVP according to echocardiography and electrocardiography criteria of asynchrony has been published. These new echocardiographic tools will help to prospectively select patients for BVP, help to guide implantation and to optimize device programming.

[Adenocarcinoma-associated nonbacterial thrombotic endocarditis as the cause of recurrent strokes]

We describe a 60-year-old female patient without vascular risk factors diagnosed with cardioembolic ischemic stroke due to an atrial septal aneurysm with a right-to-left shunt. However, further investigation after recurrent strokes revealed a nonbacterial thrombotic endocarditis (NBTE) caused by a metastatic adenocarcinoma. The presented case illustrates the difficulties in establishing the diagnosis of NBTE premortally and points out the importance of repeated echocardiographic evaluations of cardiac valves and serological examination of tumor markers in patients with recurrent strokes of unknown origin.

Linksatriales Myxom: zweites Rezidiv 20 Jahre nach der ersten Operation

We report about a 52-year old woman, who underwent a resection of a left atrial myxoma 20 years ago. Twelve years later she suffered from exertional dyspnea. Echocardiography revealed a recurrent myxoma. This was resected. Eight years later the woman suffered from disturbances of heart rhythm and from angina pectoris. The coronary arteries were normal, but a recurrent left atrial myxoma was found and operated. We conclude a long-term follow-up is inevitable in patients after the resection of a myxoma.

Echocardiographic AV-interval optimization in patients with reduced left ventricular function

BACKGROUND

Ritter's method is a tool used to optimize AV delay in DDD pacemaker patients with normal left ventricular function only. The goal of our study was to evaluate Ritter's method in AV delay-interval optimization in patients with reduced left ventricular function.

METHODS

Patients with implanted DDD pacemakers and AVB III degrees were assigned to one of two groups according to ejection fraction (EF): Group 1 (EF > 35%) and Group 2 (EF < 35%). AV delay optimization was performed by means of radionuclide ventriculography (RNV) and application of Ritter's method.

RESULTS

For each of the patients examined, we succeeded in defining an optimal AV interval by means of both RNV and Ritter's method. The optimal AV delay determined by RNV correlated well with the delay found by Ritter's method, especially among those patients with reduced EF. The intra-class correlation coefficient was 0.8965 in Group 1 and 0.9228 in Group 2. The optimal AV interval in Group 1 was 190 +/- 28.5 ms, and 180 +/- 35 ms in Group 2.

CONCLUSION

Ritter's method is also effective for optimization of AV intervals among patients with reduced left ventricular function (EF < 35%). The results obtained by RNV correlate well with those from Ritter's method. Individual programming of the AV interval is fundamentally essential in all cases.

[Evaluation of regional wall motion abnormalities of the heart--comparison with doppler tissue echocardiography, MR-tagging and levocardiography]

PURPOSE

To compare the visual analysis of magnetic resonance imaging (MRI) with the tagging technique and Doppler tissue echocardiography with invasive ventriculography in detecting and quantifying regional left ventricular wall motion abnormalities.

MATERIALS AND METHODS

Sixteen patients with coronary artery disease and a history of prior myocardial infarction underwent invasive ventriculography, Doppler tissue echocardiography and MR-tagging within one week. Regional wall motion abnormalities (WMA) were detected in all patients. WMA were graded as normal = 1; hypokinetic = 2; akinetic = 3; or dyskinetic = 4. For agreement between MRI, echocardiography, and ventriculography the kappa coefficient (kappa) according to Cohen was calculated.

RESULTS

The kappa coefficient (kappa) was 0.962 for agreement between MRI and echocardiography and 0.602 for agreement between MRI and ventriculography as well as between echocardiography and ventriculography.

CONCLUSION

Reliable analysis of regional left ventricular wall motion abnormalities is feasible using visual analysis of MR-tagging. MRI and Doppler tissue echocardiography detect more WMA than invasive ventriculography and grade them as more severe.

Neurologische Komplikationen bei infekti�ser Endokarditis

Infective endocarditis involves the brain in 20-40% of cases. The neurologic syndrome often is the presenting feature. The most frequent neurologic complication is cerebral ischemia. In these patients and those with intracranial hemorrhage, a heart murmur as well as systemic signs of inflammation point to endocarditis. The encephalopathy in endocarditis is mostly due to cerebral infarction. In bacterial meningitis and brain abscess an uncommon isolate arouses suspicion. The most important therapy is antibiotic treatment. Valve replacement improves outcome; in the acute phase of endocarditis, however, it is only necessary in a third of the patients. Neurologic complications interfere with the timing of the valve replacement. If it is urgently required, its risk is reasonable within 3 days after cerebral ischemia; if possible 2-4 weeks should be waited. Cases of successful valve replacement within 4 weeks after intracranial hemorrhage have been reported, but it is recommended to postpone it for 4-6 weeks. There are no data available for the other neurologic complications. Even today patients with endocarditis challenge the diagnostic and therapeutic capacity of various disciplines.

Multislice CT Coronary Angiography: Evaluation of an Automatic Vessel Detection Tool

PURPOSE

To investigate the potential of a new detection tool for multislice CT (MSCT) coronary angiography with automatic display of curved multiplanar reformations and orthogonal cross-sections.

MATERIALS AND METHODS

Thirty-five patients were consecutively enrolled in a prospective intention-to-diagnose study and examined using a MSCT scanner with 16 x 0.5 mm detector collimation and 400 ms gantry rotation time (Aquilion, Toshiba). A multisegment algorithm using up to four segments was applied for ECG-gated reconstruction. Automatic and manual detection of coronary arteries was conducted using the coronary artery CT protocol of a workstation (Vitrea 2, Version 3.3, Vital Images) to detect significant stenoses (> or = 50 %) in all segments of > or = 1.5 mm in diameter. Each detection tool was used by one reader who was blinded to the results of the other detection method and the results of conventional coronary angiography.

RESULTS

The overall sensitivity, specificity, nondiagnostic rate, and accuracy of the automatic and manual approach were 90 vs. 94 %, 89 vs. 84 %, 6 vs. 6 %, and 89 vs. 88 %, respectively (p = n. s.). The vessel length detected with the automatic and manual approach were highly correlated for the left main/left anterior descending (143 +/- 30 vs. 146 +/- 24 mm, r = 0.923, p < 0.001), left circumflex (94 +/- 35 vs. 93 +/- 33 mm, r = 0.945, p < 0.001), and right coronary artery (145 +/- 36 vs. 144 +/- 37 mm, r = 0.925, p < 0.001). The time required to create reformations along the coronary arteries was significantly shorter with the automatic tool compared to the manual approach (203 +/- 77 vs. 391 +/- 104 sec, p < 0.005). In 90 % of the coronary branches automatic detection required less time than the manual approach.

CONCLUSION

Automatic coronary vessel detection is feasible and reduces the time required to create reformations by a factor of approximately two without deteriorating the diagnostic accuracy.

Stirred anaerobic sequencing batch reactor containing immobilized biomass: a behavior study when submitted to different fill times

The effect of the filling stage on the behavior of a mechanically stirred anaerobic sequencing batch reactor containing biomass immobilized on 1 cm polyurethane foam cubes was investigated. The reactor was made of acrylic with a capacity of 6.3 L, treating per cycle 2.5 L synthetic low-strength wastewater with a concentration of 500 mgCOD/L, at 30+/-1 degrees C. Eight-hour cycles (tC) and agitation of 500 rpm were utilized. At the beginning of each cycle 60% of the wastewater volume was treated, sufficient to completely cover the bed. The remaining volume was added at different fill times (tF) of 10, 120, 240, 260 and 480 min. The results obtained showed that ratios of tF/tC < or = 0.5 enabled organic matter removal higher than 75% and 70% for filtered and non-filtered samples, respectively. Ratios of tF/tC > 0.5, despite operation stability, resulted in loss of efficiency and formation of viscous material, similar to extra-cellular polymeric substances.

[Left ventricular pseudoaneurysm after mitral valve replacement]

We report about a woman with a rare complication after mitral valve replacement 24 years ago. The patient had a massive hemorrhage some hours after operation. We performed invasive diagnostics because of an increasing pressure gradient across the prosthesis and revealed a left ventricular pseudoaneurysm. Before the planned reoperation the patient died suddenly. As the cause of death, we assumed a rupture of the pseudoaneurysm.

Isolated left ventricular non-compaction: cardiomyopathy with homogeneous transmural and heterogeneous segmental perfusion

This is the first description of a case of isolated non-compaction of the left ventricular myocardium, involving a 52 year old woman presenting with progressive heart failure, with analysis of myocardial perfusion by contrast echocardiography in comparison with magnetic resonance imaging.

Right atrial thrombus treated successfully with abciximab and heparin

We report here a case of right atrial thrombus diagnosed by echocardiography in a 25-year-old female patient with Hodgkin's disease receiving chemotherapy and heparin. After 24 hours therapy with the glycoprotein IIb/IIIa receptor antagonist (abciximab) with concomitant heparin the complete dissolution of the thrombus could be demonstrated by transesophageal echocardiography. To our knowledge this case represents the first use of abciximab in right atrial thrombosis.

Combined dipyridamole and dobutamine echocardiography in myocardial hibernation: comparison with thallium uptake in patients after percutaneous transluminal coronary revascularization under circulatory support

OBJECTIVE

To investigate the specificity and sensitivity of the combination of dipyridamole and dobutamine echocardiography for predicting functional recovery in patients with reduced ventricular function after coronary angioplasty.

METHODS

Twenty-five patients, mean (SD) age 60.8 (10) years, with previous myocardial infarction (> 3 months), angiographically assessed coronary artery disease, and resting regional dysfunction (left ventricular ejection fraction < 35%) were studied. They underwent rest-redistribution thallium Tl-201 single photon emission computed tomography, and low-dose pharmacologic stress echocardiography with dobutamine (up to 10 microg/kg per minute), ultra low-dose dipyridamole (0.28 mg/kg over 4 minutes), and combined dipyridamole-dobutamine administration.

RESULTS

The rate of agreement between Tl-201 and stress echo was 59% for dipyridamole, 62% for dobutamine, and 71% for combined dipyridamole-dobutamine (P <.05 vs dipyridamole and vs dobutamine). Combined dipyridamole-dobutamine showed a higher sensitivity (89%) than Tl-201, dobutamine, or dipyridamole (84%, 78%, and 80%). Specificity was lower for functional recovery prediction with Tl-201 (60%) compared with dobutamine (89%), dipyridamole (90%), and combined dipyridamole-dobutamine (91%).

CONCLUSION

Thallium is more sensitive than dipyridamole or dobutamine; the sensitivity gap is filled with combined dipyridamole-dobutamine. Pharmacologic stress echocardiography is more specific than Tl-201 scintigraphy.

Quantification of the effect of inhaled budesonide on airway inflammation in intermittent asthma by bronchitis index

The bronchitis index (BI) is a scoring system for the visual quantification of airway inflammation by flexible bronchoscopy. A prospective study was carried out to determine whether patients with intermittent asthma present a considerable visible airway inflammation. Ten steroid-naive patients with intermittent asthma taking only inhaled beta2-agonists were enrolled and received budesonide (800 microg/day) over a period of 4 weeks. The airway inflammation was assessed by flexible electronic videobronchoscopy before and after the steroid treatment phase and quantified using the BI. Despite normal pulmonary function, all patients with intermittent asthma showed a marked visible airway inflammation that was reversed by a 4-week treatment with the inhaled steroid budesonide. The present study demonstrates that the BI may be useful as a clinical research tool for the assessment and quantification of airway inflammation in asthma. Furthermore, our results support the widely recognized theory that airway inflammation is present even in patients with mild asthma, and emphasize the necessity of an early therapy with inhaled steroids.

Characterization of pectin lyase produced by an endophytic strain isolated from coffee cherries

AIMS

The effect of endophytic bacterial activity on the quality of coffee beverage was studied.

METHODS AND RESULTS

A survey of the micro-organisms in coffee cherries was performed before harvesting, and their growth on the main nutrients available in coffee cherries was determined in vitro.

CONCLUSION

Many endophytic bacteria were isolated from surface-sterilized coffee cherries. One of the pectinolytic strains was physiologically and phenotypically characterized, and was tentatively identified by partial 16S rDNA sequencing as Paenibacillus amylolyticus. This endophytic strain produced an extracellular pectinase with maximal activity at 40 degrees C and pH 7.9, and was thermostable up to 45 degrees C. EDTA and metal ions had little effect on pectin lyase activity. Km and Vmax values were 4.6 mg ml(-1) and 94.0 10(-8) mol min(-1) ml(-1), respectively.

SIGNIFICANCE AND IMPACT OF THE STUDY

Pectin lyases have been found in fungi but rarely in bacteria, and this isolate is a promising tool for regulation studies of these enzymes.

The prognostic value of myocardial viability recognized by low dose dipyridamole echocardiography in patients with chronic ischaemic left ventricular dysfunction

AIMS

The aim of this study was to assess the prognostic value of myocardial viability recognized as a contractile response to vasodilator stimulation in patients with left ventricular dysfunction in a large scale, prospective, multicentre, observational study.

METHODS AND RESULTS

Three hundred and seven patients (mean age 60 +/- 10 years) with angiographically proven coronary artery disease, previous (>3 months) myocardial infarction and severe left ventricular dysfunction (ejection fraction <35%; mean ejection fraction: 28 +/- 7%) were enrolled in the study. Each patient underwent low dose dipyridamole echo (0.28 mg x kg(-1) in 4 min). Myocardial viability was identified as an improvement of >0.20 in the wall motion score index. By selection, all patients were followed up for a median of 36 months. One-hundred and twenty-four were revascularized either by coronary artery bypass grafting (n=83) or coronary angioplasty (n=41). The only end-point analysed was cardiac death. In the revascularized group, cardiac death occurred in one of the 41 patients with and in 16 of the 83 patients without a viable myocardium (2.4% vs 19.3%, P<0.01). Outcome, as estimated by Kaplan-Meier survival, was better for patients with, compared to patients without, a viable myocardium, who underwent coronary revascularization (97.6 vs 77.4%, P=0.01). Using a Cox proportional hazards model, the presence of myocardial viability was shown to exert a protective effect on survival (chi-square 4.6, hazard ratio 0.1, 95% CI 0.01-0.8, P<0.03). The survival rate in medically treated patients was lower than in revascularized patients irrespective of the presence of a viable myocardium (79.7% vs 86.2, P=ns).

CONCLUSION

In severe left ventricular ischaemic dysfunction, myocardial viability, as assessed by low dose dipyridamole echo, is associated with improved survival in revascularized patients.

Endotracheal balloon dilatation and stent implantation in benign stenoses

BACKGROUND

Tracheal reconstruction is the treatment of choice in nontumorous tracheal stenoses, but recurrences and concomitant medical conditions limit this approach. We investigated the outcome after balloon dilatation and silicone stent implantation.

METHODS

Forty-two patients with inoperable tracheal stenoses underwent balloon dilatation and afterward silicone stent implantation. Patients were divided into two groups, in group A 24 patients received tracheal stents as a temporary treatment. In group B, definitive stenting was done in 18 patients with severe concomitant medical conditions that did not allow for stent removal.

RESULTS

Immediate results were satisfactory in all patients. In group A, stents could be removed in 12 patients after a mean interval of 20 months. Restenting was not required during the following 18.9 months. Twelve patients are still waiting for stent removal after a mean follow-up of 20 months. In group B, mean follow-up is now 48.4 months. Complications included retained secretions, dislocation, and granuloma formation.

CONCLUSIONS

Stenting after balloon dilatation is safe and effective in benign tracheal stenoses. After temporary use, stents can be removed when local and general conditions permit. In all other patients, stenting proved beneficial for 5 years as more definitive treatment.

The BMP antagonists cerberus-like and noggin do not interact during mouse forebrain development

Mouse cerberus-like encodes for a secreted factor of the Cerberus/Dan family. This molecule has neural inducing capabilities and can bind to BMP-4 and nodal molecules in the extracellular space. When cerberus-like is inactivated, its function may be compensated for another molecule, since no abnormalities can be observed in the mouse mutant. Compensation mechanisms have been shown to occur between the BMP antagonists chordin and noggin. Here we report the generation of cerberus-like-/-; noggin-/- double mutants to uncover a possible compensation by noggin in cer-l-/- mutant. Double mutants were obtained and failed to show any further detectable defects beside the ones presented by the noggin-/- single mutant. Contrarily to chordin and noggin, mouse cerberus-like and noggin cannot compensate for each other during mouse embryogenesis.

Linksventrikuläre Volumenreduktion: Prä- und postoperative Evaluierung mit der Cine MRT

AIM

To evaluate the role of cine magnetic resonance imaging (MRI) in the preoperative assessment and postoperative follow-up of patients undergoing left ventricular (LV) reduction surgery.

PATIENTS AND METHODS

6 patients with cardiomegaly were examined on a 1.5 T MR imager before and after LV reduction surgery. The heart was imaged along the short and long axes using a breath-hold ECG-triggered cine gradient-echo sequence for assessing ventricular and valvular morphology and function and performing volumetry (end-diastolic and end-systolic volumes, ejection fraction).

RESULTS

Postoperatively, the mean ejection fraction increased from 21.7% to 33.4% and the end-diastolic and end-systolic left ventricular volumes decreased in all patients (304.0 and 252.5 ml before to 205.0 and 141.9 ml after surgery). Mean myocardial mass decreased slightly from 283.8 g to 242.7 g. Differences were significant for all parameters (p < 0.05). MRI allowed for the reliable assessment of post-operative valve morphology and yielded additional findings such as the presence of mitral valve insufficiency or ventricular thrombus.

CONCLUSIONS

Cine MRI provides relevant information prior to left ventricular reduction surgery and reliably depicts functional and morphological changes in the early post-operative follow-up.

Coronary artery bypass grafts: improved electron-beam tomography by prolonging breath holds with preoxygenation

In 45 patients with coronary bypass grafts, the breath-hold interval with and that without preoxygenation was measured. Its effect on depiction of the distal graft anastomosis at electron-beam tomography was evaluated. Preoxygenation prolonged the breath-hold interval in most patients, thereby allowing greater anatomic coverage including more distal anastomoses. Preoxygenation may improve scanning of coronary bypass grafts and increase detectability of graft stenoses.

Value of bronchial artery embolisation with platinum coils in tumorous pulmonary bleeding

We performed bronchial artery embolizations (BAE) using platinum coils with Dacron fibres in 30 consecutive patients with haemoptysis due to bronchial carcinoma. The aim of the study was to compare immediate results of bleeding cessation, recurrence and survival rates with a historical control group of 15 patients with tumorous pulmonary bleeding who were treated conservatively (non-BAE-group). Bronchial artery embolisation with platinum coils stopped active bleeding in all patients immediately. Comparing the BAE group and controls the cessation of first time haemoptysis (BAE 100% versus non-BAE 93%) and the rates of bleeding recurrence (BAE 50% versus non-BAE 47%) were similar in either group. In case of recurrent bleeding, repeated BAE led to a definite cessation of pulmonary haemorrhage in every case. In contrast, all patients with recurrent haemoptysis without a repeated BAE (8 patients, 27%) and all patients with bleeding recurrence in the non-BAE group died from pulmonary haemorrhage (8 patients, 53%). The mean survival time of the BAE group was significantly longer compared with the non-BAE group, 139 (range: 1-818) days versus 62 (range: 1-186) days (P<0.05). We conclude that consistent BAE proved beneficial in tumorous pulmonary bleeding, particularly with regard to the permanent arrest of haemorrhage in case of recurrence.

Abnormal proliferative response of the carotid artery of spontaneously hypertensive rats after angioplasty may be related to the depolarized state of its smooth muscle cells

Hypertension is one of the major precursors of atherosclerotic vascular disease, and vascular smooth muscle abnormal cell replication is a key feature of plaque formation. The present study was conducted to examine the relationship between hypertension and smooth muscle cell proliferation after balloon injury and to correlate neointima formation with resting membrane potential of uninjured smooth muscle cells, since it has been suggested that altered vascular function in hypertension may be related to the resetting of the resting membrane potential in spontaneously hypertensive rats (SHR). Neointima formation was induced by balloon injury to the carotid arteries of SHR and renovascular hypertensive rats (1K-1C), as well as in their normotensive controls, i.e., Wistar Kyoto (WKY) and normal Wistar (NWR) rats. After 14 days the animals were killed and the carotid arteries were submitted to histomorphometric and immunohistochemical analyses. Resting membrane potential measurements showed that uninjured carotid arteries from SHR smooth muscle cells were significantly depolarized (-46.5 +/- 1.9 mV) compared to NWR (-69 +/- 1.4 mV), NWR 1K-1C (-60.8 +/- 1.6 mV), WKY (-67.1 +/- 3.2 mV) and WKY 1K-1C (-56.9 +/- 1.2 mV). The SHR arteries responded to balloon injury with an enhanced neointima formation (neo/media = 3.97 +/- 0.86) when compared to arteries of all the other groups (NWR 0.93 +/- 0.65, NWR 1K-1C 1.24 +/- 0.45, WKY 1.22 +/- 0.32, WKY 1K-1C 1.15 +/- 0.74). Our results indicate that the increased fibroproliferative response observed in SHR is not related to the hypertensive state but could be associated with the resetting of the carotid smooth muscle cell resting membrane potential to a more depolarized state.

PEST sequences in cAMP-dependent protein kinase subunits of the aquatic fungus Blastocladiella emersonii are necessary for in vitro degradation by endogenous proteases

During Blastocladiella emersonii germination, the regulatory (R) and the catalytic (C) subunits of the cAMP-dependent protein kinase (PKA) are rapidly and concurrently degraded, after PKA activation in response to a transient increase in intracellular cAMP levels. The possibility that PEST sequences could be acting as proteolytic recognition signals in this process was investigated, and high score PEST sequences were found in both B. emersonii R and C subunits. Deletions in the PEST sequences were obtained by site-directed mutagenesis and the different PKA subunits were independently expressed in Escherichia coli. Proteolysis assays of the various R and C recombinant forms, using B. emersonii cell extracts as the source of proteases, showed a strong correlation between the presence of high score PEST sequences and susceptibility to degradation. Furthermore, the amino-terminal sequence of the proteolytic fragments indicated that the cleavage sites in both subunits are located at or near the PEST regions. The PEST sequence in B. emersonii C subunit, which when deleted or disrupted leads to resistance to proteolysis, is entirely contained in the 72-amino-acid extension located in the N-terminus of the protein. C subunit mutants carrying deletions in this region displayed little difference in their kinetic properties or enzyme thermostability. These results suggest that the N-terminal extension may only play a role in C subunit degradation.

Cerberus-like is a secreted BMP and nodal antagonist not essential for mouse development

Mouse cerberus-like (cer-l) is a member of the Cerberus/Dan family of secreted factors. As other members of this family of proteins, Cer-l functions in the extracellular space, inhibiting signaling molecules. Here we show that the neural-inducing and mesoderm-inhibiting activities of Cer-l result from specific binding to BMP and Nodal molecules, respectively. These properties resemble the ones from the related factor Xenopus Cerberus. However, Xenopus Cerberus in addition to BMP4 and Nodal also binds to and inhibits Wnt proteins. We show that Cer-l does not directly inhibit Wnt signals. A null allele of the mouse Cer-l gene was generated by targeted inactivation in ES cells. Homozygous embryos show no anterior patterning defects, are born alive, and are fertile. Since mouse Cer-l and Xenopus Cerberus differ in biochemical activities, we propose the existence of additional members of this family of inhibitors, which may compensate for the loss of cer-l.

Pharmacological characterization of RMP-7, a novel bradykinin agonist in smooth muscle

RMP-7 is a bradykinin (BK) agonist designed to be resistant to kininases such as angiotensin-converting enzyme (ACE). Pharmacological assays were performed with RMP-7 in isolated guinea-pig ileum and rat mesenteric artery. RMP-7 induced contractile responses in the guinea-pig ileum, where the apparent affinity of the peptide (pD2) was significantly lower than that determined for BK (7.3 +/- 0.07 vs. 8.3 +/- 0.05, respectively). HOE-140 blocked this effect indicating that B2 receptor was involved. Captopril (1 microM) had no potentiating effect on RMP-7 but increased pD2 value determined for BK (8.8 +/- 0.1), confirming a high resistance of RMP-7 to the ACE. In rat mesenteric artery, RMP-7 induced endothelium-dependent relaxation (7.8 +/- 0.4), with a higher affinity than that of BK which induced vasodilatation only in the presence of 1 microM captopril (6.9 +/- 0.36). Nevertheless, the maximum effect induced by RMP-7 was lower than that of BK in contrast to that observed in guinea-pig ileum although B2 receptor was involved in both cases. We concluded that: RMP-7 is greatly resistant to the ACE and that the receptor sites activated by RMP-7 and BK show important differences in vascular and non-vascular preparations probably due to the different sensitivity of the B2 receptor to RMP-7.

Chromosomal integration of heterologous DNA in Escherichia coli with precise removal of markers and replicons used during construction

A set of vectors which facilitates the sequential integration of new functions into the Escherichia coli chromosome by homologous recombination has been developed. These vectors are based on plasmids described by Posfai et al. (J. Bacteriol. 179:4426-4428, 1997) which contain conditional replicons (pSC101 or R6K), a choice of three selectable markers (ampicillin, chloramphenicol, or kanamycin), and a single FRT site. The modified vectors contain two FRT sites which bracket a modified multiple cloning region for DNA insertion. After integration, a helper plasmid expressing the flippase (FLP) recombinase allows precise in vivo excision of the replicon and the marker used for selection. Sites are also available for temporary insertion of additional functions which can be subsequently deleted with the replicon. Only the DNA inserted into the multiple cloning sites (passenger genes and homologous fragment for targeting) and a single FRT site (68 bp) remain in the chromosome after excision. The utility of these vectors was demonstrated by integrating Zymomonas mobilis genes encoding the ethanol pathway behind the native chromosomal adhE gene in strains of E. coli K-12 and E. coli B. With these vectors, a single antibiotic selection system can be used repeatedly for the successive improvement of E. coli strains with precise deletion of extraneous genes used during construction.

Pulmonary involvement in diffuse cutaneous systemic sclerosis: broncheoalveolar fluid granulocytosis predicts progression of fibrosing alveolitis

OBJECTIVE

The clinical course of fibrosing alveolitis (FA) in patients with systemic sclerosis (SSc) may vary considerably from stable condition for years to continuous fatal progression. This prospective study aimed at identifying the prognostic value of bronchoalveolar lavage fluid (BALF) analysis in FASSc.

METHODS

Seventy three consecutive patients with SSc and clinical signs of pulmonary involvement were enrolled. Every patient underwent clinical examination, lung function tests, computed tomography (CT), gallium scan, echocardiography, and bronchoalveolar lavage (BAL). Forty nine patients, 26 with pathological and 23 with normal BALF findings were prospectively followed up for two years and re-evaluated annually.

RESULTS

At baseline, 51 subjects (70%) showed radiological signs of lung fibrosis and/or alveolitis by CT and diffusion capacity for carbon monoxide (DLco) was decreased in 47 patients (64%). Thirty five patients (48%) had pathological BALF findings. BALF differential counts included BALF granulocytosis in 18, BALF lymphocytosis in 12, and a mixed increase of both granulocytes and lymphocytes in five patients. On follow up, a progression of FA with a significant decrease of DLco was only observed in patients with BALF granulocytosis. In contrast, patients with BALF lymphocytosis or normal BALF cell count had stable lung function parameters during the study period. In none of our patients echocardiography showed evidence of pulmonary hypertension.

CONCLUSION

BALF granulocytosis predicts progression of FA with deterioration of lung function, which is most sensitively monitored by DLco. Immunosuppressive treatment is recommended in patients with granulocytic FASSc.

Effect of cholecalciferol treatment on the relaxant responses of spontaneously hypertensive rat arteries to acetylcholine

We studied the effect of oral cholecalciferol treatment on the endothelium-dependent vascular relaxation and hyperpolarization induced by acetylcholine (ACh), which is impaired in spontaneously hypertensive rats (SHR). Adult female SHR and normotensive Wistar-Kyoto rat (WKY) controls received 125 microg of cholecalciferol per kilogram body weight per day for 6 weeks. The responses to ACh of the isolated mesenteric vascular bed and mesenteric artery rings were measured, as well as the smooth muscle cell membrane potential. After cholecalciferol treatment, the systolic blood pressure and basal perfusion pressure of the mesenteric vascular bed of the SHR fell to control levels. The relaxant and hyperpolarizing effects of ACh, which are reduced in SHR, were also brought to control levels after cholecalciferol treatment. These effects of ACh were inhibited by N(omega)-nitro-L-arginine in SHR and by apamin in WKY. After cholecalciferol treatment, SHR hyperpolarizing responses showed the same inhibition pattern as those of WKY. This indicates that, after cholecalciferol treatment, SHR vascular mesenteric preparation responses to ACh are mediated by endothelium-derived hyperpolarizing factor, which induces activation of Ca(2+)-dependent K(+) channels, as in WKY. In untreated SHR, the ACh-mediated response is entirely due to ACh acting via the release of nitric oxide.

Enteric bacterial catalysts for fuel ethanol production

The technology is available to produce fuel ethanol from renewable lignocellulosic biomass. The current challenge is to assemble the various process options into a commercial venture and begin the task of incremental improvement. Current process designs for lignocellulose are far more complex than grain to ethanol processes. This complexity results in part from the complexity of the substrate and the biological limitations of the catalyst. Our work at the University of Florida has focused primarily on the genetic engineering of Enteric bacteria using genes encoding Zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase. These two genes have been assembled into a portable ethanol production cassette, the PET operon, and integrated into the chromosome of Escherichia coli B for use with hemicellulose-derived syrups. The resulting strain, KO11, produces ethanol efficiently from all hexose and pentose sugars present in the polymers of hemicellulose. By using the same approach, we integrated the PET operon into the chromosome of Klebsiella oxytoca to produce strain P2 for use in the simultaneous saccharification and fermentation (SSF) process for cellulose. Strain P2 has the native ability to ferment cellobiose and cellotriose, eliminating the need for one class of cellulase enzymes. Recently, the ability to produce and secrete high levels of endoglucanase has also been added to strain P2, further reducing the requirement for fungal cellulase. The general approach for the genetic engineering of new biocatalysts using the PET operon has been most successful with Enteric bacteria but was also extended to Gram positive bacteria, which have other useful traits for lignocellulose conversion. Many opportunities remain for further improvements in these biocatalysts as we proceed toward the development of single organisms that can be used for the efficient fermentation of both hemicellulosic and cellulosic substrates.

Different pathways for Ca2+ mobilization by angiotensin II and carbachol in the circular muscle of the guinea-pig ileum

Ca2+ pathways activated by angiotensin II and carbachol were evaluated in the circular muscle of the guinea-pig ileum by recording mechanical and electrical activities. Transient contractions induced by angiotensin II were greatly reduced by Ca2+ removal from the medium whereas carbachol-induced responses were not significantly altered. Nifedipine had no effect on the responses to both agonists. A high concentration of tetrodotoxin (0.1 microM) inhibited angiotensin II-induced contractile responses without affecting the depolarization, whereas 1 mM Ni2+ inhibited the mechanical and electrical effects. Neither tetrodotoxin nor Ni2+ affected carbachol-induced effects. These results indicate that angiotensin II-induced phasic contractions depend on extracellular Ca2+ but not on voltage-dependent L-type Ca2+ channels. It is suggested that angiotensin II activates Ni2+-sensitive Na+ and non-specific cationic channels, whereas the responses to carbachol are dependent on receptor-activated Ca2+ release. Furthermore the different response of the longitudinal and circular muscles to the inhibitory effects of tetrodotoxin and Ni2+ on the angiotensin II- and carbachol-induced contractions indicates that these agonists exert their own myogenic effects on each layer and are able to trigger different Ca2+ mobilization pathways.

Comparison of combination of dipyridamole and dobutamine during echocardiography with thallium scintigraphy with thallium scintigraphy to improve viability detection

The aim of this study was to investigate the relation between radioisotopic and echocardiographic markers of myocardial viability and their correlation with functional recovery after coronary revascularization. Myocardial viability can be detected by techniques exploring various aspects of cell physiology: thallium-201 scintigraphy and dobutamine and dipyridamole echocardiography focus on cell membrane integrity, beta-1 and adrenoceptor, and A2-adenosine receptor-mediated inotropic response, respectively. Fifty-seven patients (mean age 60+/-8 years) with previous myocardial infarction (>3 months), angiographically assessed coronary artery disease, and resting regional dysfunction underwent rest-redistribution 201-thallium scintigraphy and low-dose pharmacologic stress echo with dobutamine (up to 10 microg/kg/min), very low dose regimen of dipyridamole (0.28 mg/kg over 4 minutes), and combined dipyridamole-dobutamine. Criteria for viability in a 13-segment model for both techniques were percent peak activity in redistribution images >55% for thallium-201 and a decrease in wall motion score >1 grade (1 [normal] to 4 [dyskinetic]) for stress echo. Thirty patients underwent coronary revascularization (bypass surgery in 8, angioplasty in 22) and were followed up at 4 weeks from intervention with a resting echocardiogram. The rate of agreement between thallium-201 and stress echo was 63% for dipyridamole, 66% for dobutamine, and 74% for combined dipyridamole-dobutamine (p <0.05 vs dipyridamole and dobutamine). In the 30 patients who underwent revascularization, a regional resting dyssynergy was observed in 225 segments, assuming that postrevascularization functional recovery (which occurred in 126 segments) was the gold standard; combined dipyridamole-dobutamine showed a higher sensitivity (90% confidence interval [CI] 85% to 95%) than thallium-201, dobutamine, or dipyridamole (87%, CI 81% to 92%; 82%, CI 76% to 89%; and 82%, CI 76% to 89%, respectively). Specificity was lower for viability recognition with thallium-201 (61%, CI 51% to 71%) than with dobutamine (93%, CI 88% to 98%), dipyridamole (95%, CI 91% to 99%), and combined dipyridamole-dobutamine (92%; CI 87% to 97%). Combined adrenergic and adenosinergic stimulation recruits an inotropic reserve in a significant proportion of segments with preserved thallium uptake that were nonresponders after either dipyridamole or dobutamine. When functional recovery after successful revascularization is considered as the postoperative gold standard, thallium has a higher sensitivity than dipyridamole or dobutamine; this sensitivity gap is filled with combined dipyridamole-dobutamine. The specificity of all forms of pharmacologic stress echo is better than thallium-201.

Autonomic effects of dipyridamole stress testing on frequency distribution of RR and QT interval variability

Transient myocardial ischemia and associated changes in the autonomic nervous system may influence heart rate and ventricular repolarization to variable degrees. This study evaluated the effect of dipyridamole (DIP) induced ischemia on the autonomic balance by spectral analysis of RR and QT intervals variability. Patients with coronary artery disease undergoing DIP stress echocardiography were studied. From high resolution ECG recordings, RR and QT interval measurements were performed by a dynamic template-matching algorithm. A time-variant analysis was used to estimate power in the LF (0.05-0.15 Hz) and in the HF (0.15-0.4 Hz) band of RR and QT interval spectra. Patients were grouped in ischemic and nonischemic subgroups based on the echocardiographic detection of wall-motion abnormalities. In patients without ischemia (n = 28), DIP caused a decrease in LF power and an increase in HF power of the RR and QT interval variability, indicating concordant changes of both intervals. In contrast, patients with inducible ischemia (n = 11) showed a decrease in HF power of the RR interval spectra and an increase of HF power of QT interval spectra. Furthermore, LF power was increased for RR but decreased for QT interval spectra. Our study suggests that DIP induced ischemia causes a loss of autonomic coupling between heart rate and ventricular repolarization for sympathetic and parasympathetic activities. This lability in ventricular repolarization may constitute an arrhythmogenic substrate during acute ischemia in patients with coronary artery disease.

Impaired function of alpha-2 adrenoceptors in smooth muscle of mesenteric arteries from spontaneously hypertensive rats

The alpha2-adrenoceptor function in mesenteric arteries of spontaneously hypertensive rats (SHR) was investigated by comparing membrane potential changes in response to adrenergic agonists in preparations from female SHR, Wistar-Kyoto (WKY) and normotensive Wistar rats (NWR). Resting membrane potential was found to be less negative in mesenteric arteries from SHR than in those from NWR and WKY. Apamin induced a decrease in the membrane potential of mesenteric artery rings without endothelium from NWR and WKY, but had no effects in those from SHR. Both UK 14,304 and adrenaline, in the presence of prazosin, induced a hyperpolarization that was significantly lower in de-endothelialized mesenteric rings from SHR than in those from NWR and WKY. In mesenteric rings with endothelium, however, similar hyperpolarization was observed in the three strains. In NWR mesenteric rings with endothelium the hyperpolarization induced by activation of alpha2-adrenoceptors was abolished by apamin, whereas in intact SHR mesenteric rings this hyperpolarization was slightly reduced by apamin and more efficiently reduced by Nomega-nitro-L-arginine. It is concluded that the activity of potassium channels coupled to alpha2-adrenoceptors is altered in the smooth muscle cells of SHR mesenteric arteries, contributing to their less negative membrane potential. On the other hand, the endothelial alpha2-receptors are functioning in mesenteric vessels from SHR and their stimulation induces a hyperpolarization mainly through the release of nitric oxide.

Relationship between haemodynamics and morphology in pulmonary hypertension. A quantitative intravascular ultrasound study

BACKGROUND

Intravascular ultrasound imaging of the pulmonary arteries has been demonstrated to be a reliable method of quantifying vessel diameter, luminal area and pulsatility. Simultaneous measurement of flow velocity and its response to vasodilators allows the relationship between morphology and functional compromise to be studied, especially endothelial dysfunction.

METHODS

In 51 patients (mean age = 49.8 +/- 12.6 years, 17 female) we performed right heart catheterization and simultaneous intravascular ultrasound of pulmonary artery branches. The patients were divided in two groups: group 1 with normal pulmonary artery pressure and pulmonary vascular resistance, and group 2 with pulmonary hypertension (peak pulmonary artery pressure > 30 mmHg and/or mean pulmonary artery pressure > 20 mmHg). Vessel wall and lumen were studied using a 2.9 F intravascular ultrasound catheter with a 30 MHz phased array transducer. Measurement of blood flow velocity was accomplished by a Doppler flow wire (0.018 inch). The maximal flow change during acetylcholine infusion (adjusted to 10(-6); 10(-5), and 10(-4) M concentration in the blood vessel) was measured.

RESULTS

There were no significant differences between groups 1 and 2 with respect to age (48.5 +/- 14.3 years vs 50.3 +/- 12.3 years; P = ns), gender (4 female/8 male vs 13 female/26 male; P = ns), luminal area of the vessel segment in which the intravascular ultrasound measurements were obtained (11.8 +/- 6.1 mm2 vs 16.7 +/- 14.3 mm2; P = ns), internal diameter (3.9 +/- 1.2 mm vs 4.2 +/- 1.7 mm; P = ns), and external diameter (6.1 +/- 1.3 mm vs 6.9 +/- 2.1 mm; P = ns). Cross-sectional images of the pulmonary artery wall demonstrated a single ring with high echodensity with a thin inner layer regarded as intima in group 1. In contrast, the majority of patients (n = 35/39) in group 2 demonstrated a thickening of the intimal layer and/or a disturbance of layering of the echogenic arterial wall. The relative wall thickness was higher in group 2 than in group 1 (22.5 +/- 10.4% vs 15.3 +/- 6.5%; P < 0.05). There were no significant correlations between pulmonary artery pressure and wall thickness pulmonary artery pressure and area change in the cardiac cycle, acetylcholine-dependent increase in pulmonary flow and morphological changes in the vessel wall.

CONCLUSION

We conclude that intravascular ultrasound is capable of detecting morphological changes in the pulmonary vessel wall in pulmonary hypertension and that vessel wall hypertrophy of small pulmonary segment arteries, as detected by intravascular ultrasound, is not predictive of functional vasodilatory response of resistance vessels of the same vessel area.