Exochelins of Mycobacterium tuberculosis remove iron from human iron-binding proteins and donate iron to mycobactins in the M. tuberculosis cell wall.

To multiply and cause disease in the host, Mycobacterium tuberculosis must acquire iron from the extracellular environment at sites of replication. To do so, the bacterium releases high-affinity iron-binding siderophores called exochelins. In previous studies, we have described the purification and characterization of the exochelin family of molecules. These molecules share a common core structure with another type of high-affinity iron-binding molecule located in the cell wall of M. tuberculosis: the mycobactins. The water-soluble exochelins differ from each other and from water insoluble mycobactins in polarity, which is dependent primarily upon the length and modifications of an alkyl side chain. In this study, we have investigated the capacity of purified exochelins to remove iron from host high-affinity iron-binding molecules, and to transfer iron to mycobactins. Purified desferri-exochelins rapidly removed iron from human transferrin, whether it was 95 or 40% iron saturated, its approximate percent saturation in human serum, and from human lactoferrin. Desferri-exochelins also removed iron, but at a slower rate, from the iron storage protein ferritin. Purified ferri-exochelins, but not iron transferrin, transferred iron to desferri-mycobactins in the cell wall of live bacteria. To explore the possibility that the transfer iron from exochelins to mycobactins was influenced by their polarity, we investigated the influence of polarity on the iron affinity of exochelins. Exochelins of different polarity exchanged iron equally with each other. This study supports the concept that exochelins acquire iron for M. tuberculosis by removing this element from host iron-binding proteins and transferring it to desferri-mycobactins in the cell wall of the bacterium. The finding that ferri-exochelins but not iron transferrin transfer iron to mycobactins in the cell wall underscores the importance of exochelins in iron acquisition. This study also shows that the variable alkyl side chain on the core structure of exochelins and mycobactins, the principal determinant of their polarity, has little or no influence on their iron affinity.

Effect of compression stockings on cutaneous microcirculation: Evaluation based on measurements of the skin thermal conductivity.

OBJECTIVE: To study of the microcirculatory effects of elastic compression stockings. MATERIALS AND METHODS: In phlebology, laser Doppler techniques (flux or imaging) are widely used to investigate cutaneous microcirculation. It is a method used to explore microcirculation by detecting blood flow in skin capillaries. Flux and imaging instruments evaluate, non-invasively in real-time, the perfusion of cutaneous micro vessels. Such tools, well known by the vascular community, are not really suitable to our protocol which requires evaluation through the elastic compression stockings fabric. Therefore, we involve another instrument, called the Hematron (developed by Insa-Lyon, Biomedical Sensor Group, Nanotechnologies Institute of Lyon), to investigate the relationship between skin microcirculatory activities and external compression provided by elastic compression stockings. The Hematron measurement principle is based on the monitoring of the skin's thermal conductivity. This clinical study examined a group of 30 female subjects, aged 42 years ±2 years, who suffer from minor symptoms of chronic venous disease, classified as C0s, and C1s (CEAP). RESULTS: The resulting figures show, subsequent to the pressure exerted by elastic compression stockings, an improvement of microcirculatory activities observed in 83% of the subjects, and a decreased effect was detected in the remaining 17%. Among the total population, the global average increase of the skin's microcirculatory activities is evaluated at 7.63% ± 1.80% (p < 0.0001). CONCLUSION: The results from this study show that the pressure effects of elastic compression stockings has a direct influence on the skin's microcirculation within this female sample group having minor chronic venous insufficiency signs. Further investigations are required for a deeper understanding of the elastic compression stockings effects on the microcirculatory activity in venous diseases at other stages of pathology.

Value of ELISA using antigen 60 for the diagnosis of tuberculosis in children.

We evaluated the possible value of enzyme-linked immunosorbent assay (ELISA) using antigen 60 (A60) for improved diagnosis of tuberculosis in children. Results obtained in 31 children with active tuberculosis and in 16 patients with tuberculous infection without disease were compared with the results of 198 control subjects with no mycobacterial disease. In control children, anti-A60 IgG increased with age and the optical density (OD) in ELISA assays rose from .079 +/- .053 (OD +/- SD) in children younger than 5 years old to 0.146 +/- 0.082 OD in children older than 5 years. In control subjects younger than 2 years old, IgG OD values were significantly higher in BCG-vaccinated children than in nonvaccinated children. At a chosen specificity of 98 percent, a positive serodiagnosis was observed in 68 percent of children with clinically active tuberculosis. In these children with active disease, smears were positive in only 26 percent of cases and mycobacterial cultures yielded the organism in 45 percent of cases. None of the infected children without disease had high IgG OD values. IgM measurements were also evaluated. Mean values from control and diseased children overlapped, leading to a low sensitivity (19 percent) in children with clinically tuberculosis active. We conclude that anti-A60 IgG measurement is a rapid and low-cost technique that enhances the diagnosis of clinically active tuberculosis in children and may distinguish recent infection without disease from infection with disease.

Effects of environmental temperature and exercise on the biochemical characteristics of hamster intestine.

The effects of increasing environmental temperature and of exercise on some biochemical characteristics of the intestinal mucosa were analyzed in hamsters to determine whether damage occurs to the intestine during exercise, because long-distance runners complain of cramp, diarrhea, or retrostaltic symptoms, especially when exercise is performed at high temperatures. Two sets of experiments were carried out on groups of five animals. First, one group stayed at rest at 20 degrees C while another group performed exercise for 30 min at the same temperature. Second, one group of animals remained at rest at 20 degrees C for 16 h, a second group was placed at 32 degrees C for the same period, and a third group was subjected to the latter treatment but in addition performed two 20-min exercises. The animals were killed immediately after the experiment. After the small bowel was removed, biopsies were taken for histological examination, and the remaining small bowel tissue was homogenized for biochemical analysis. During exercise performed at 20 degrees C or during exposure to 32 degrees C, the DNA weight (expressed as a function of the protein weight) increased; the specific activity of sucrase, leucine aminopeptidase, diamine oxidase, and maltase decreased; spermine and putrescine content generally decreased; and the weight of mucosal proteins per length of intestine did not vary significantly. When exercise was performed at 32 degrees C, we noted few modifications in the values of the intestinal parameters tested, i.e., changes in only the weight of mucosa expressed as a function of bowel length and, perhaps, the spermine or putrescine content.

[Significance of photoplethysmography in the diagnosis of deep venous insufficiency]. / Intérêt de la photopléthysmographie dans le diagnostic de l'insuffisance veineuse profonde.

In chronic venous insufficiency, photoplethysmography, in addition to the clinical and Doppler examinations, offers important informations in the differential diagnosis between deep and superficial venous insufficiency. It is a simple, reproductible, non invasive test with data similar to venous pressure measurements. Photoplethysmography permits to set up quantitative criteria of venous insufficiency. It establishes the role of reflux in the dysfunction of the leg venous pump, and makes it possible to adjust for prescription of additional explorations, in particular popliteal or femoral dynamic phlebography. Furthermore, photoplethysmography offers a solid criterion to differentiate between various therapeutic surgeries: surgery of the superficial network, surgery of collateral veins, surgery to restore the deep venous network. Moreover, photoplethysmography is a useful tool to quantitatively appreciate the results of the venous insufficiency treatment. In conclusion, photoplethysmography appears as an additional examination necessary for functional exploration in chronic venous insufficiency. Its use in practical angiology is going to develop in view of its interesting results and its reasonable cost.

[Recurrent varicose veins in the groin after surgery]. / Les récidives au pli de l'aine après chirurgie des varices.

Recurrence of varicose veins following surgery of the long saphenous system are common. It is important to differentiate several causes. These, in fact, dictate the therapeutic decision. Physiopathologically, there are different types of recurrences: persistent reflux from the femoral veins into the superficial varicose network due to: an incomplete long sapheno-femoral high ligation (crossectomy), a neoangiogenesis at the level of the previous sapheno-femoral junction. separate termination of an incompetent long saphenous vein (LSV) into the common femoral vein or the superficial femoral vein (antero lateral or postero medial tributaries of LSV); persistent reflux from perineal and (or) paricto-abdominal veins into the varicose network of the thigh. Dynamic popliteal phlebography was, until the advent of echo-doppler, the author's method of choice for investigation as it was easier to interpret than varicography. At the present time it is only requested on the rare occasions where doubt persists even after echo-doppler. Additionally, with this investigation, the reflux (major or minor) can be analysed at its point of origin and a map of the underlying varicose network can be drawn. Therapeutically, we make the following suggestions: in the presence of a site of major reflux (incomplete crossectomy, high flow neoangiogenesis, separate termination of the saphenous tributaries), a further operation would be justified. The removal of the site of reflux can be associated with the placing of a PTFE patch on the common femoral vein. in the presence of a site of minor reflux, sclerotherapy or, preferably, echosclerotherapy would appear to be the treatment of choice. Elimination of the site (s) of reflux must be associated with suppression of the underlying varicose network by sclerotherapy or phlebectomy.

[Effectiveness of combined repeat surgery and sclerotherapy after failure of surgical treatment of varicose veins]. / Valeur de l'association chirurgie itérative-sclérothérapie après échec du traitement chirurgical des varices.

UNLABELLED: From January 1985 to December 1986 one hundred and five patients (145 lower limbs) have been treated by redosurgery followed by sclerotherapy. It is a selected group because redosurgery decision was taken both by surgeon and angiologists on the basis that a significant reflux between the profunda system and the superficial system was present. The aim of this retrospective study was to assess results obtained by this therapeutic association with a follow-up from 5 to 6 years. Failure mechanisms of initial treatment, symptoms, preoperative investigations, redosurgery procedures are analysed. Results were estimated both by a questionnaire and an independent audit. Patient estimation: symptoms improvement 65%; cosmetics improvement 68%. Audit estimation: SYMPTOMS: excellent or good results: 78%, fair results: 12%, poor results: 10%. Cosmetics: excellent or good results: 30%, fair results: 53%, poor results: 17%. 82% of patients plebiscited redosurgery in cooperation with sclerotherapy.

[Understanding the poor results after surgery for superficial venous insufficiency]. / Comprendre les mauvais résultats après chirurgie de l'insuffisance veineuse superficielle.

Effectiveness and value of surgical treatment in varicose veins remains difficult to assess for many reasons. They are discussed in details in front of this general review devoted to poor results after varicose vein surgery. An other pathology is often associated with venous insufficiency and is frequently missed and responsible of poor results. Many factors contribute to make uneasy assessment of poor results. The lack of objective criteria to appreciate the natural evolution of varicose disease different from one patient to another. The difficulty to grade clinical disease severity. Results published before the use of modern preoperative investigations make their report obsolete. Precise data of surgical treatment undertaken are often not detailed. The quality of therapists (surgeon or phlebologist) is uneasy to check. The difficulty to assess results after treatment: subjective results (patient) vs objective results (audit). Duration of follow-up. Imprecise vocabulary to qualify results. Clinical assessment remains the cornerstone but supplementary investigations must be undertaken. Duplex-Scan is currently accepted as the gold standard investigation. Phlebography or (and) plethysmography can be helpful in some cases. After detailed assessment patients can be classified in different groups. This classification allows to determinate the most adequate treatment. In some selected patients redosurgery is strongly recommended. Prevention of recurrence after surgical treatment of varicose veins can not be complete. Strict respect of several rules can however reduce it. They can be summarised as follows: Respect of temporary of definitive contraindications to surgical treatment. Thorough investigation before surgery. Preoperative precise aim of what must be treated by the surgical procedure. Correct operative procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pre- and postoperative contribution of Doppler ultrasonography in superficial venous surgery of the popliteal fossa]. / Apport de l'écho-Doppler pré et postopératoire dans la chirurgie veineuse superficielle de la fosse poplitée.

AIMS OF THE STUDY: Does preoperative Duplex Scan (DS) allow to determine anatomy of the ending of the short saphenous vein (SSV), gastrocnemius vein (GV) and reflux in popliteal vein (PV), SSV and GV. Postoperative DS was performed to detect deep vein thrombosis (DVT) and GV thrombosis. MATERIAL AND METHODS: From June 94 to November 95 one hundred and eighty lower limbs operated for SSV were included consecutively and prospectively. Mean age in these 154 patients was 52 yr (24-80) with a sex ratio 4F/1M. An anatomical classification was previously defined. Type A: separate termination of SSV and GV; Type B: common ostium of SSV and GV in the popliteal vein; Type C: common trunk of the SSV and GV; Type D: Others. Forty-eight limbs (26.10%) had ligation of GV: 21 (11.10%) for reflux and 27 (16%) for anatomical or surgical reasons. Ten type A with GV reflux (10/31 = 32%) were not treated. Eighty two patients (45%) received preventive low molecular weight heparin (LMWH) treatment including the 48 limbs whose GV were ligated. RESULTS: Anatomical correlation between DS and surgery findings were calculated. Positive predictive values of DS in the different types were: A, 77%; B, 68%; C, 90%; D, 79%. That gave a global predictive value of 80%. Two limited DVT were identified in group D by postoperative DS (2/10 = 1.1%). These two patients had complete recanalization of PV without reflux. In the group of limbs which had ligation of GV we identified 37.5% of GV thrombosis. In the group without ligation of GV we found 3% of GV thrombosis. CONCLUSION: Duplex scanning appears to be the investigation of choice before surgery for superficial vein incompetence in the popliteal fossa. It is a reliable investigation to determine termination patterns of SSV and GV (80%). It brings to the surgeon essential information which helps in the management of surgical procedure and particularly to ligation of gastrocnemius veins. But at this time there is no consensus on this point. The occurrence of DVT after SSV surgery including GV ligation was very low. Two questions remain: is anticoagulation necessary in all patients or selective after surgery of the SSV? is Duplex Scan mandatory during postoperative monitoring? On the basis of this study, one recommendation can be made: A routine postoperative DS is necessary after ligation of the GV or when the dissection of the popliteal fossa has been extensive (Type D).

Accidental dural puncture: combination of prophylactic methods to avoid post-dural puncture headache.

Accidental dural puncture (ADP) is a common complication of epidural catheter insertion, and may lead to post-dural puncture headache (PDPH), especially in obstetric patients. Epidural blood patch (BP) is the most effective treatment of PDPH. Prophylactic BP has shown its efficacy to prevent PDPH; nevertheless, this method may be insufficient. We report an ADP case before induction of labor in a 28-year-old parturient. To avoid PDPH, an intrathecal catheter was immediately inserted after ADP and an epidural catheter was also inserted at the interspace above. Catheters were kept in place for more than 24hours. A prophylactic BP was performed immediately after removal of the intrathecal catheter. The patient did not experience any headache. This combination of treatments (intrathecal catheter insertion+prophylactic BP) may be a good alternative approach to prevent PDPH, even if it has to be warranted by other clinical studies.

A French-Italian survey on the prevalence of isolated varices (C2) and complicated varices (C2+). Results of a multi-centre study conducted by the SFA and the SFP under the auspices of the European Venous Forum.

AIM: The advanced CEAP classification allows one to differentiate between isolated varicose veins (C2) and complicated varicose veins (C2, 3 - C2, 3, 4 - C2, 4 or C2, 3, 4, 5 etc) named (C2+). METHODS: The main objective of this study was to identify when using the advanced classification the prevalence of isolated varicose veins (C2) and complicated varicose veins (C2+) among patients consulting vascular specialists and to compare their symptomatic status and the data issued from the advanced CEAP including also the headings, Anatomy (A), Etiology (E) and Pathophysiology (P). RESULTS: 171 patients were evaluated, 100 in France and 71 in Italy. The prevalence of C2 and C2+ was the same in both countries: 64.4% in France and 63.3% in Italy. Also no difference was found in the prevalence of other descriptors: etiology, anatomy or pathophysiology. The time to complete the advanced form was less than 5 minutes for 65% of the investigators. CONCLUSION: The advanced CEAP is easy to use in daily pratice. We have the same prevalence of patients in France and in Italy, who consulted for isolated varicose veins or associated with other signs of chronic venous disorders.

Characterization of exochelins of Mycobacterium avium: evidence for saturated and unsaturated and for acid and ester forms.

Mycobacterium avium secretes iron-binding siderophores called exochelins. The exochelins from M. avium have previously been reported to have unsaturated side chains that terminate in carboxylic acid. In contrast, our data show the side chains to be both saturated and unsaturated and to terminate with either a carboxylate or methyl ester.

Characterization of exochelins of the Mycobacterium bovis type strain and BCG substrains.

Pathogenic mycobacteria must acquire iron in the host in order to multiply and cause disease. To do so, they release abundant quantities of siderophores called exochelins, which have the capacity to scavenge iron from host iron-binding proteins and deliver it to the mycobacteria. In this study, we have characterized the exochelins of Mycobacterium bovis, the causative agent of bovine and occasionally of human tuberculosis, and the highly attenuated descendant of M. bovis, bacillus Calmette-Guérin (BCG), widely used as a vaccine against human tuberculosis. The M. bovis type strain, five substrains of M. bovis BCG (Copenhagen, Glaxo, Japanese, Pasteur, and Tice), and two strains of virulent Mycobacterium tuberculosis all produce the same set of exochelins, although the relative amounts of individual exochelins may differ. Among these mycobacteria, the total amount of exochelins produced is greatest in M. tuberculosis, intermediate in M. bovis, and smallest in M. bovis BCG.

Outbreak of gut colonization by Pseudomonas aeruginosa in immunocompromised children undergoing total digestive decontamination: analysis by pulsed-field electrophoresis.

We analyzed an outbreak of gut colonization by Pseudomonas aeruginosa occurring in an intensive care hematology unit by using conventional typing methods and pulsed-field electrophoresis. In October and November 1989, the feces of four immunocompromised children undergoing total digestive decontamination were colonized by P. aeruginosa. Ten isolates were obtained from the gut flora in pure culture. Retrospective investigations found that one P. aeruginosa isolate from stools of one of the patients was already present at high counts 6 months before the outbreak. This patient had been discharged from the unit in May 1989 and had been readmitted concomitantly with the outbreak. Only pulsed-field electrophoresis could demonstrate that a single epidemic strain was present in the fecal flora of the children. This strain had probably been brought into the unit by the patient with chronic fecal carriage.

Iron acquisition by Mycobacterium tuberculosis: isolation and characterization of a family of iron-binding exochelins.

Mycobacterium tuberculosis, the primary agent of tuberculosis, must acquire iron from the host to cause infection. To do so, it releases high-affinity iron-binding siderophores called exochelins. Exochelins are thought to transfer iron to another type of high-affinity iron-binding molecule in the bacterial cell wall, mycobactins, for subsequent utilization by the bacterium. In this paper, we describe the purification of exochelins of M. tuberculosis and their characterization by mass spectrometry. Exochelins comprise a family of molecules whose most abundant species range in mass from 744 to 800 Da in the neutral Fe(3+)-loaded state. The molecules form two 14-Da-increment series, one saturated and the other unsaturated, with the increments reflecting different numbers of CH2 groups on a side chain. These series further subdivide into serine- or threonine-containing species. The virulent M. tuberculosis Erdman strain and the avirulent M. tuberculosis H37Ra strain produce a similar set of exochelins. Based on a comparison of their tandem mass spectra, exochelins share a common core structure with mycobactins. However, exochelins are smaller than mycobactins due to a shorter alkyl side chain, and the side chain of exochelins terminates in a methyl ester. These differences render exochelins more polar than the lipophilic mycobactins and hence soluble in the aqueous extracellular milieu of the bacterium in which they bind iron in the host.

Lipophilic siderophores of Mycobacterium tuberculosis prevent cardiac reperfusion injury.

Reperfusion injury, which occurs upon the reintroduction of blood flow to an ischemic organ, is responsible for considerable damage in heart attacks and strokes. However, no treatment for reperfusion injury is currently available. A major cause of reperfusion injury is the iron-mediated generation of hydroxyl radical (.OH). In this study we have explored the capacity of novel iron chelators called "exochelins" to prevent reperfusion injury. Exochelins, siderophores of Mycobacterium tuberculosis, are unique iron chelators because they are lipid soluble, and hence able to enter cells rapidly. In the iron-free state, exochelins prevented .OH formation. Desferri-exochelins prevented oxidative injury to cultured cardiac myocytes, and did so more rapidly and effectively than the nonlipid soluble iron chelator deferoxamine. The capacity of various desferri-exochelins to protect myocytes from oxidative injury varied directly with their solubility in lipid. Infused into isolated rabbit hearts during reperfusion after a period of ischemia, desferri-exochelins dramatically improved systolic and diastolic left ventricular function, preserved coronary flow, reduced release of the cardiac enzyme lactic dehydrogenase, and reduced myocardial concentrations of .OH metabolites. Thus, highly diffusible desferri-exochelins block injury caused by .OH production and have potential for the treatment of reperfusion injury.