Multipass open-path Fourier-transform infrared measurements for nonintrusive monitoring of gas turbine exhaust composition

The detection limits for NO and NO2 in turbine exhausts by nonintrusive monitoring have to be improved. Multipass mode Fourier-transform infrared (FTIR) absorption spectrometry and use of a White mirror system were found from a sensitivity study with spectra simulations in the mid-infrared to be essential for the retrieval of NO2 abundances. A new White mirror system with a parallel infrared beam was developed and tested successfully with a commercial FTIR spectrometer in different turbine test beds. The minimum detection limits for a typical turbine plume of 50 cm in diameter are approximately 6 parts per million (ppm) for NO and 9 ppm for NO2 (as well 100 ppm for CO2 and 4 ppm for CO).

Myocardial flow reserve parametric map, assessed by first-pass MRI compartmental analysis at the chronic stage of infarction

Regional myocardial flow and flow reserve (MFR) were assessed by compartmental analysis of Gd-enhanced MRI first-pass data in 7 patients with atypical chest pain, and in 15 patients with previous transmural myocardial infarction. The FE product (Flow x Extraction coefficient), derived from the modified Kety equation, was measured in regions corresponding to the Tetrofosmine-SPECT fixed defect and in remote normal regions. The FE product at rest and hyperemic FE product were similar in healed revascularized tissues (70.5 +/- 15.6 and 112.5 +/- 19.5 ml/mn/100 g, respectively) and in normal myocardium (76.2 +/- 18.3 and 142.2 +/- 33.0, respectively). In contrast, the FE index (48.8 +/- 15.2 and 60.7 +/- 18.0, respectively, P < 0.01 versus the two previous groups) and the MFR (1.27 +/- 0.20 vs. 1.91 +/- 0.29 in normal regions) were reduced in healed fibrotic tissues when the infarct-related artery remained occluded. Myocardial flow reserve maps allowed correct identification of regions corresponding to an occluded infarct-related artery.

Determination of cutin-bound residues of chlorothalonil by immunoassay

An indirect competitive enzyme-linked immunosorbent assay (ELISA) was used to determine photochemically cutin-bound residues of chlorothalonil in enzymatically isolated tomato and apple fruit cuticles. The samples were spiked, irradiated, exhaustively extracted, and depolymerized with boron trifluoride complex resulting in a soluble depolymerisate. With this procedure, the ELISA could be calibrated with free target molecules for the quantification of originally bound chlorothalonil residues. In fruit cuticles that were irradiated for 8 h by simulated sunlight, 0.030 and 0.068 mg/g photoinduced cutin-bound residues of wax-free cuticles (calculated as chlorothalonil) were determined for tomatoes and apples, respectively. For the used antibody mAb chl. 4/11, cross-reactivities with derivatives of chlorothalonil simulating different types of cuticle-bound residues are given and discussed.

New approaches in the management of choroidal neovascular membrane in age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly population. The prevalence is reported to be 1.2-1.4% in several population-based epidemiological studies. Currently 25-30 million people worldwide are blind due to AMD. With the aging world population it is bound to increase significantly, and could become a significant public health problem in next two decades, with serious socio-economic implications. Several strategies are today available to treat the wet form of AMD, which is responsible for significant visual loss. These were until recently confined to laser photocoagulation, and subretinal surgery, but today two other modalities, namely, radiation and photodynamic therapy, are available. These treatment modalities however, are aimed at preservation of vision only, and not at reversing the process of the disease. Further research on antiangiogenic drugs and gene therapy could significantly help AMD patients.

[Cartography of absolute myocardial perfusion with magnetic resonance imaging. Methods and results]

Ultra-rapid dynamic MRI (one image per heart beat) can follow the progression of the intra-myocardial signal during the first passage of diffusable gadolinium chelates injected as a bolus through a peripheral vein. A quantitative evaluation of myocardial perfusion is possible using a compartmental model of analysis. Absolute myocardial flow can be measured at rest and during hyperaemia induced by dipyridamole. It is possible to associate functional mapping, corresponding to parametric images of the flow indices, to the global evaluation. The ratio between the values obtained during hyperaemia and under basal conditions correspond to the myocardial reserve. The principles, results and limitations of this method are discussed in the light of published results, underlining the advantages of absolute flow measurement and of the differences between the results of MRI and myocardial scintigraphy.

Differential expression of linker histone variants in Euplotes crassus

Two genes have been cloned from the ciliate Euplotes crassus that encode proteins with sequence similarity to the linker histones from a variety of organisms. One gene, H1-1, is present on a 1.3-kb macronuclear DNA molecule and encodes a 16.2- kDa protein. The second gene, H1-2, is present on a 0.7-kb DNA molecule and encodes an 18.8-kDa protein. Both H1-1 and H1-2 are expressed in vegetative cells, but the two genes exhibit very different patterns of expression during macronuclear development. H1-1 transcripts accumulate during conjugation and during the final rounds of DNA amplification. H1-2 transcripts accumulate after the onset of polytene chromosome formation and remain high throughout the remainder of macronuclear development. H1-1 is the major perchloric-acid-soluble protein from macronuclei. The pattern of gene expression and the macronuclear location of the H1-1 protein indicate that H1-1 is the predominant linker histone in vegetative macronuclei.

The impact of knee joint flexion on infrainguinal vascular grafts: an angiographic study

OBJECTIVES

To characterise the morphologic behaviour of infrainguinal vascular grafts during flexion of the knee.

DESIGN

A prospective angiographic study.

MATERIALS AND METHODS

In 64 infrainguinal bypass grafts, intravenous digital subtraction angiography was performed within the first postoperative week. Frontal and lateral projection angiograms with the knee joint extended and with a 80-90 degrees flexion were taken. The distal anastomosis of the bypass was performed below-knee in 49 cases (18 in situ veins, 8 reversed veins with an anatomic course, 2 reversed veins with an extra-anatomic course, 4 composite grafts, 15 synthetic grafts with an anatomic course (14 polytetrafluoroethylene (ePTFE), 1 polyurethane), and two synthetic grafts with an extra-anatomic course. Fifteen ePTFE prostheses were implanted in the above-knee position.

RESULTS

Out of 64 cases a total of 16 grafts showed stenotic kinking during flexion: two of the 18 in situ vein grafts, four of the 12 reversed vein grafts implanted with an anatomic course, one of the two reversed vein grafts implanted in an extra-anatomic site, eight of the 15 synthetic grafts crossing the knee, 0 of the two extra-anatomic ePTFE grafts, and one of the 15 cases of above-knee femoropopliteal ePTFE grafts.

CONCLUSIONS

Stenotic kinking due to knee flexion can affect all kinds of bypass grafts including vein grafts placed anatomically and above-knee prostheses.

Decreased sympatho-adrenal activity in diabetic patients with autonomic dysfunction following mental stress

The sympathetic nervous system is of major importance in the regulation of numerous physiological functions. While it is clearly established that there is a decreased noradrenergic status in people with autonomic neuropathy, the epinephrine secretion is much more controversial. Basal and mental stress-stimulated plasma catecholamine levels were measured in 42 diabetic patients with and without pathological cardiovascular function tests and in 13 healthy, non-diabetic control subjects. In addition, the excretion of catecholamines was measured in a 24 h urine collection and compared with the stress stimulated plasma levels. During mental stress exposure a diminished epinephrine secretion was found in diabetic patients with autonomic neuropathy compared with diabetic patients without neuropathy and the healthy control group (p < 0.05: respectively). The decreased epinephrine response to mental stress was strongly correlated with a diminished urinary excretion of this "neurotransmitter' (r = 0.46; p < 0.01). Diabetic patients suffering from cardiovascular autonomic neuropathy exhibit a diminished sympatho-adrenal response following mental stress exposure. Both measurement of urinary and mental stress stimulated plasma epinephrine levels following mental stress provide reliable information regarding sympatho-adrenal activity in diabetic patients.

Assessment of painful ureterohydronephrosis during pregnancy by MR urography

The purpose of this study was to assess the value of the fast imaging sequence called RARE (rapid acquisition with relaxation enhancement) MR urography (or RMU) in pregnant women with painful ureterohydronephrosis. A total of 17 pregnant women with an acute flank pain were examined with RMU. Results were compared with those of US, X-rays and the evolution of symptoms. The gold standard techniques used to evaluate the results of MR urography were US when it showed the entire dilated urinary tract and the nature of the obstruction (9 cases), limited intravenous urography (IVU) when performed (3 cases) or endoscopic procedure (5 cases). The accuracy of RMU in the detection of urinary tract dilatation and the localization of the level of obstruction was excellent (sensitivity 100% in our series). The determination of the type of obstruction, intrinsic vs extrinsic, was always exact. The RMU technique alone could not specify the exact nature of the obstruction. The RMU technique is able to differentiate a physiological from a pathological ureterohydronephrosis during pregnancy. It could be considered as the procedure of choice when US failed to establish the differential diagnosis.

[Endovascular treatment of hemorrhagic renal angiomyolipoma with platinum microcoils]

Haemorrhage is the major complication of renal angiomyolipoma and is classically treated surgically, but embolization constitutes an alternative treatment. Improvement of catheters and embolization materials now allows highly selective embolization. The authors present a case in which the use of a variable stiffness catheter and platinum microcoils allowed highly selective embolization of a haemorrhagic renal angiomyolipoma while preserving the functional renal parenchyma.

Fast imaging MR assessment of ureterohydronephrosis during pregnancy

PURPOSE

to assess the value of the fast imaging sequence called RARE-MR-Urography (RMU) for the diagnosis of pathologic ureterohydronephrosis during pregnancy.

MATERIALS AND METHODS

15 pregnant women with an acute flank pain were examined with RMU. Results were compared with those of ultrasonography (US), X-rays, and the evolution of symptoms.

RESULTS

the accuracy of RMU in the detection of urinary tract dilatation and the localization of the level of obstruction was excellent (100%). The determination of the type of obstruction, intrinsic vs. extrinsic, was always exact. RMU alone cannot specify the exact nature of the intrinsic obstruction. Ultrasonography gave less sensitive information in terms of level (60%) and type of obstruction (53%).

CONCLUSION

RMU is able to differentiate a physiological from a pathologic ureterohydronephrosis during pregnancy. It could be considered as a procedure of choice for special cases when US failed to establish this differential diagnosis.

Evaluation of RARE-MR urography in the assessment of ureterohydronephrosis

OBJECTIVE

The goal of this prospective study was to evaluate the value of the fast imaging sequence called RARE-MR urography (RMU) for the diagnosis of ureterohydronephrosis.

MATERIALS AND METHODS

Sixty-nine patients underwent this procedure. The results were compared with those obtained by intravenous urography (IVU) and ultrasonography (US).

RESULTS

The accuracy of RMU in the detection of urinary tract dilatation and the localization of the level of obstruction was excellent (100%). The determination of the type of obstruction, intrinsic versus extrinsic, was 80% by IVU and 60% for RMU. The RMU sequence alone could not specify the nature of the obstruction. Functional information about the obstructed collecting system could not be obtained.

CONCLUSION

The RMU technique may be considered in the following circumstances: contraindications to IVU (allergy to contrast medium, severe renal failure), impairment of renal excretion, and failure to locate the level of obstruction by US. The absence of ionizing radiations favors the promotion of this procedure to study ureterohydronephrosis during pregnancy.

[Captopril test for detecting renal artery stenosis: changes in plasma renin concentration]

The aim of this study was to demonstrate the diagnostic value of changes in active renin concentration during the captopril test (measurements of plasmatic active renin concentrations, before 12.5 or 37.5 mg of captopril p.o., and 30 and 90 minutes after) in order to screen a significant renal artery stenosis. After a renal angiography, 88 hypertensive patients suspected of renovascular hypertension were classified according to the percentage of stenosis in the main renal artery: class I (< 30% - n = 50), II (30 to < 75% - n = 21), III (75 to < 90% - n = 8) and IV (90 to 100% - n = 11). The results of the captopril test were compared to those of renal angiography. The active renin before the test (basal AR), the greater increase in active renin after captopril (max AR), the difference between max AR and basal AR (DIF) and the active renin relative change after the test (RC) were compared in the 4 classes (ANOVA). There were no differences in diastolic blood pressure (> or = 90 mmHg) natriuresis (100 mmol/24 h in mean) between these different classes. The basal AR, the max AR, the DIF and the RC significantly differed between the 4 classes. They were greater in class III and IV than in class I. The positive criteria for the captopril test were max AR, DIF and RC. The positivity thresholds were max AR > or = 70 ng/l, DIF > or = 50 ng/l and RC > or = 165% (upper limit in the class I 95% confidence interval for each criterion).(ABSTRACT TRUNCATED AT 250 WORDS)

[Contribution of imaging to the study of aortic aneurysms]

All aortic aneurysms require a positive diagnosis, a differential diagnosis and an assessment of extension. Several exploratory methods can be contemplated. In patients with warning symptoms, conventional radiology may point to the diagnosis. The reference method remains retrograde aortography which may be either conventional and seriographic or, better, radiocinematic with orthogonal projections and, if possible, digital. The site and morphology of the aneurysm, and in particular its inner channel are thus demonstrated. Computerized tomography is less invasive and usually of great value, notably for the horizontal, thoracic and abdominal aorta, not only to confirm the diagnosis but also to determine the size of the inner channel, parietal thrombi and aortic walls, as well as relations with nearby structures. Other, totally non-invasive methods are widely utilized to explore aortic aneurysms. These are ultrasonography and its variants (notably Doppler-echocardiography and the transoesophageal route), and magnetic resonance imaging which provides three-dimensional and anatomical views of the vessel. These last two examinations alone usually confirm and outline the aortic aneurysms. They must therefore be utilized as first-line examination, arteriography it is various forms being reserved for emergencies or special cases.

Serum-erythropoietin concentration during acute cardiogenic pulmonary edema

Reduced oxygen tension is regarded as the primary physiologic signal for the production of erythropoietin (EPO). There is little information available about early changes of EPO production in man due to severe hypoxia. The purpose of the present study was to examine the time course of EPO in serum of patients with acute cardiogenic pulmonary edema (ACPE). In 29 patients (seventy-five +/- six years, mean age +/- SEM) who were hospitalized within two hours after onset of symptoms of ACPE, serum EPO concentrations were monitored for up to seventy-two hours. At the moment of admission all patients showed significantly increased EPO concentrations of 121 +/- 64 mU/mL (mean +/- SEM) compared with a healthy population (15-35 mU/mL). Twenty-three patients who recovered within thirty minutes (group A) exhibited a quick return of their EPO serum levels to normal. The remaining 6 patients (group B) had a protracted clinical course and their EPO concentration showed a further increase up to the end of the observation period. The comparative monitoring of concentrations of alpha-1-proteinase inhibitor, antithrombin III, C-reactive protein, fibronectin, hapotoglobin, and transerrin in serum and plasma revealed no significant changes. Thus a major contribution of fluid shifts into or from the intravascular compartment to the observed changes in EPO concentration seems to be unlikely. The data suggest that the production and release of EPO in the kidneys due to altered oxygen delivery is a fast-responding mechanism.

Pharmacokinetics and dose response after intravenous and subcutaneous administration of recombinant erythropoietin in patients on regular haemodialysis treatment or continuous ambulatory peritoneal dialysis

The pharmacokinetics and dose response of recombinant human erythropoietin (rhEPO), administered intravenously and subcutaneously, were studied in chronic haemodialysis (HD) patients and in patients on chronic ambulatory peritoneal dialysis (CAPD). Furthermore, two products differing in the presence of albumin as preservative were compared. Although the pharmacokinetics differed after intravenous and subcutaneous administration, the dose response was the same. There is no statistically significant difference in the pharmacokinetics between the rhEPO in HD and CAPD, nor had the presence of albumin as preservative an influence on the pharmacokinetics.

[Nutrition, metabolic and endocrine complications during extrarenal dialysis]

Patients with chronic renal failure treated by maintenance dialysis often have nutritional disorders, metabolic disorders concerning lipids, proteins and carbohydrates, and disorders of endocrine systems involved in the regulation of these metabolisms. These disorders are difficult to diagnose, as their clinical symptoms are few and of little pathognomonic value. Hence the need for anthropometric measurements as well as biochemical and physiological exploration of metabolic pathways for intermittent overall evaluation and longitudinal follow-up. These patients have reduced subcutaneous fat reserves, intolerance to carbohydrates by resistance to insulin (partially corrected by haemodialysis), low levels of plasma aminoacids, notably valine, type IV hyperlipidaemia with low levels of essential fatty acids, fragile immune system and increased requirements for vitamins B, especially B6. Dietary recommendations include: food energy 35 kiloCal/kg bodyweight/day; proteins 1 to 1.2 g/kg bodyweight/day (50 p. 100 of which must be complete proteins) and supplements of vitamins. Dialysis must be optimal for clearance of nitrogen compounds and body homeostasis.

Recombinant human erythropoietin activates a broad spectrum of progenitor cells

Twenty uremic patients on regular hemodialysis received recombinant human Erythropoietin (rhEPO) in a dosage of 50 U/kg body wt (N = 9) and 80 U/kg body wt (N = 11), respectively, three times weekly. The number of circulating hemopoietic progenitor cells colony-forming unit-granulocyte-erythrocyte-macrophage (CFU-mix), burst-forming unit-erythroid (BFU-E) and colony-forming-granulocyte-macrophage (CFU-GM) in peripheral blood were assayed weekly by means of a commonly applied in vitro clonal assay. A significant increase of peripheral CFU-mix, BFU-E and CFU-GM could be observed within one week of supplementation therapy in both groups. The increase of BFU-E was followed by a rise of hematocrit within four and three weeks, respectively. These results suggest that the stimulatory in vivo effect of rhEPO administered in therapeutical doses is not restricted to the erythroid lineage but also includes progenitor cells committed to the myeloid lineage (CFU-GM) as well as the multipotent progenitors CFU-mix. The increment of circulating progenitor cells was seen with a dosage of 80 U/kg body wt and 50 U/kg body wt as well.