Thermotropic liquid crystalline glycolipids.

Are the liquid crystalline properties of the materials of living systems important in biological structures, functions, diseases and treatments? There is a growing consciousness that the observed lyotropic, and often thermotropic liquid crystallinity, of many biological materials that possess key biological functionality might be more than curious coincidence. Rather, as the survival of living systems depends on the flexibility and reformability of structures, it seems more likely that it is the combination of softness and structure of the liquid-crystalline state that determines the functionality of biological materials. The richest sources of liquid crystals derived from living systems are found in cell membranes, of these glycolipids are a particularly important class of components. In this critical review, we will examine the relationship between chemical structure and the self-assembling and self-organising properties of glycolipids that ultimately lead to mesophase formation.

Activity of sulfate-reducing bacteria in human periodontal pocket.

Samples of subgingival dental tissues were examined for the presence of sulfate-reducing bacteria (SRB). Using enrichment cultures, SRBs were detected in 9 of 17 individuals. A pure culture of SRB was obtained from one sample collected from a patient with type IV periodontal disease. The characterization of this isolate showed that it belongs to the genus Desulfovibrio. The isolate used pyruvate, lactate, glucose, fructose, and ethanol as the sole source of carbon. However, the isolate was unable to use acetate and methanol as a carbon source, indicating it as an incomplete oxidizer unable to carry out the terminal oxidation of substrates. Apart from using sulfate as electron acceptor, the isolate also used thiosulfate and nitrate as an electron acceptor. It has the ability to use a variety of nitrogen sources, including ammonium chloride, nitrate, and glutamate. The optimum growth temperature of the isolate was 37 degrees C and the optimum pH for growth was 6.8. The SRB isolate contained the electron carrier desulfoviridin. The numbers of SRB in the mouth are assumed to be limited by sulfate. Potential sources of sulfate in the subgingival area include free sulfate in pocket fluid and glycosaminoglycans and sulfur-containing amino acids from periodontal tissues.

Syntheses and interfacial behaviour of neoglycolipid analogues of glycosyl ceramides.

Four glycosyl ceramides analogues having D-galactose or 2-acetamido-2-deoxy-D-glucose moieties linked to enantiomeric lipids have been synthesised to study their interfacial behaviour at the air/water interface. The lipid chains were prepared in two steps by opening 1,2-epoxyhexadecane using Jacobsen kinetic hydrolytic resolution (KHR) followed by an azidosilylation reaction of the diol so obtained. Glycosylation reactions were realised either with 2,3,4,6-tetra-O-benzoyl-alpha-D-galactopyranosyl trichloroacetimidate or 1,3,4,6-tetra-O-acetyl-2-allyloxycarbonylamino-2-deoxy-beta-D-glucopyranose as donors and (2R)- or (2S)-2-azidohexadecanol derivatives as acceptors. Transformation of the azido glycosides into N-acylated products was done by a modified Staudinger reaction in the presence of fatty acyl chlorides. The four neoglycolipids are able to form a condensed monolayer at the air/water interface; their pi-A isotherm diagrams are similar to that described for the natural glycosyl ceramides. The detailed analysis of the isotherms, taking into account the chirality of the lipid chains, allowed to determine the contribution of the different parts of the molecule under the monolayer packing.

Syntheses of neoglycolipids with hexitol spacers between the saccharidic and the lipidic parts.

Four neoglycolipids having 2-amino-2-deoxy-D-glucose or D-galactose moieties linked to the lipidic part by a glucitol or a mannitol spacer-arm have been synthesized. The key step of the synthetic strategy was the regiospecific or regioselective beta-glycosylation of partially protected glucitol or mannitol acceptors by either 3,4,6-tri-O-acetyl-2-deoxy-2-iodo-alpha-D-mannopyranosyl azide or 2,3,4,6-tetra-O-benzoyl-alpha-D-galactopyranosyl trichloroacetimidate donors.

Syntheses of amphiphilic glycosylamides from glycosyl azides without transient reduction to glycosylamines.

Protected glycosyl azides react with acyl chlorides in the presence of triphenylphosphine to afford glycosylamides in high yields, at room temperature. Starting from the beta-glycosyl azides, the reaction is highly stereoselective and occurs with retention of configuration, whereas the alpha-azido anomers display a lower stereoselectivity giving rise to alpha/beta mixtures of glycosylamides. The reaction was applied to several monosaccharidic azides and to lactosyl azide with various acyl chlorides; it was shown to be of general use for preparing 1,2-trans beta-glycosylamides.

Comparative outcome of heart-lung and lung transplantation for pulmonary hypertension.

Despite the development of several lung transplantation procedures, the most advantageous for pulmonary hypertension remains controversial. Between 1986 and February 1992, 30 patients with end-stage primary pulmonary hypertension (n = 24), chronic pulmonary embolism (n = 4), and hystiocytosis X (n = 2) underwent heart-lung (n = 21), double lung (n = 8), or single lung (n = 1) transplantation. Indications for double lung transplantation were similar to those for heart-lung transplantation, and the preoperative clinical and hemodynamic parameters were not significantly different between the two groups. There were no intraoperative deaths, but two reoperations were needed for pleural hematoma. Five early deaths were related to graft failure (two heart-lung transplantations), mediastinitis (one heart-lung transplantation), multiorgan failure (one double lung transplantation), and aspergillosis (one double lung transplantation). There was a similar improvement in early (days 0 and 2) and late (6 months postoperatively) right-sided hemodynamic function in patients undergoing heart-lung and double lung transplantation. Three double lung transplant recipients had early and reversible left ventricular-failure. The early postoperative course of the one patient who had single lung transplantation was characterized by severe pulmonary edema, left ventricular failure, and persistent desaturation and later on by moderate pulmonary hypertension and an important ventilation/perfusion mismatch. The pulmonary function results were also similar in the heart-lung and double lung transplantation groups. The overall projected 2- and 4-year survivals were 49% and 41%, respectively, and were not significantly different between the heart-lung and double lung recipients. Results demonstrate that heart-lung and double lung transplantation are equally effective in obtaining early and durable right-sided hemodynamic and respiratory improvement and similar respiratory function. In patients with pulmonary hypertension, double lung transplantation should be preferred to single lung transplantation because of the critical postoperative course and the uncertain long-term results of single lung transplantation.

Anterior transcervical-thoracic approach for radical resection of lung tumors invading the thoracic inlet.

We describe an original anterior transcervical-thoracic approach required for a safe exposure and radical resection of non-small-cell lung cancer that has invaded the cervical structures of the thoracic inlet. Through a large L-shaped anterior cervical incision, after the removal of the internal half of the clavicle, the following steps may be performed: (1) dissection or resection of the subclavian vein; (2) section of the anterior scalenus muscle and resection of the cervical portion of the phrenic nerve, if invaded; (3) exposure of the subclavian and vertebral arteries; (4) dissection of the brachial plexus up to the spinal foramen; (5) section of invaded ribs; and (6) en bloc removal of chest wall and lung tumor, either directly or through an extension of the cervical incision into the deltopectoral groove. An additional posterior thoracotomy may be required for resection of the chest wall below the second rib. Between 1980 and 1991, 29 patients underwent radical en bloc resection of the inlet tumor, chest wall (ribs 1 and 2), and underlying lung, either through the anterior transcervical approach alone (n = 9) or with an additional posterior thoracotomy (n = 20). The inferior root of the brachial plexus, either alone (n = 11) or with the phrenic nerve (n = 4), was involved and resected in 15 patients (52%). Twelve patients (41%) had a vascular involvement that included the subclavian artery alone (n = 3); subclavian artery and subclavian vein (n = 3); subclavian artery, subclavian vein, and vertebral artery (n = 2); subclavian artery and vertebral artery (n = 1); subclavian vein alone (n = 1); vertebral artery alone (n = 1), or subclavian artery and vertebral artery (n = 1). The subclavian artery was revascularized either with a prosthetic replacement (n = 7) or an end-to-end anastomosis (n = 2), and the median graft patency was 18.5 months (range, 6 to more than 73 months); only 1 patient had postradiotherapy graft occlusion in the revascularized artery 6 months after operation. We performed 14 wedge resections, 14 lobectomies, and 1 pneumonectomy. There were no operative or hospital deaths. Postoperative radiotherapy (median, 56 Gy) was given to 25 (86%) patients, either alone (n = 14) or in combination with adjuvant systemic chemotherapy (n = 11). With a median follow-up time of 2.5 years, overall 2- and 5-year survivals were 50% and 31%, respectively. This transcervical-thoracic approach affords a safe exposure and radical resection of non-small-cell lung cancer involving the thoracic inlet and results in encouraging long-term survival.

Selective protections on 2-allyloxycarbonylamino-1,6-anhydro-2-deoxy-beta-D-glucopyranose.

Regioselective monoacetylation of 2-allyloxycarbonylamino-1,6-anhydro-2-deoxy-beta-D-glucopyranose (1) gave a mixture of 3-O-acetyl and 4-O-acetyl derivatives, the structures of which were established by two-dimensional, phase-sensitive NOESY and confirmed by chemical proofs. The benzylation of 1, on the other hand, led to 2-allyloxycarbonylamino-1,6-anhydro-3,4-di- (5) or 2-allyloxycarbonylamino-1,6-anhydro-2-N-benzyl-3,4-di-O-benzyl-2-d eoxy-beta-D- glucopyranose (10). The regioselective cleavage of 5 with titanium tetrachloride gave the expected 3-O-benzyl derivative, the structure of which was ascertained by chemical proofs; the same reaction performed on 10 led to the opening of the anhydro ring to afford 3-benzyl-[3,4-di-O-benzyl-1,2-dideoxy-alpha-D-glucopyrano]-[2,1-d] -2- oxazolidone.

Effectiveness of earplugs in high-intensity impulse noise.

The efficiency of different types of earplugs was assessed by means of Békésy audiometry following the exposure of 42 human subjects to weapon impulses. The peak pressure of the impulses ranged from 2.3-27.8 kPa (from 161 to 183-dB peak SPL) and the A-weighted equivalent level (over 8 h) of each exposure ranged from 100-114 dB. All subjects wore earplugs fitted by an experienced individual. The devices tested included one brand of conventional foam earplugs and a number of different models of perforated earplugs, one type of which had been previously shown to provide nonlinear attenuation. Perforated earplugs were tested because they provide better speech communication than conventional passive earplugs, and in the nonlinear case also afford attenuation that increases with the peak pressure of the impulses. The temporary threshold shifts (TTSs) observed in these experiments were very small and indicated no significant hazard for hearing. Well-fitted perforated earplugs seem to be able to protect the ear from infrequent exposures to the high-level impulses produced by small and large weapons while allowing good speech communication, and without impairing the operational capacity of soldiers who must remain aware of their acoustic environment.

Increased lung clearance of 99mTcDTPA in allograft lung rejection. The Paris-Sud Lung Transplant Group.

To investigate whether lung 99mTc-DTPA clearance is altered during allograft lung rejection, a group of four double lung and 24 heart-lung transplant patients was studied using serial measurement of the clearance rate of aerosolized 99mTc-DTPA (DTPA-Cl), in association with pulmonary function tests, bronchoalveolar lavage, and transbronchial lung biopsies. Using histologic diagnosis as a standard, we compared 56 episodes with normal lung histology to 32 episodes with allograft lung rejection. A control group of 20 healthy nonsmokers was used to define normal DTPA-Cl. In patients with normal lung histology, DTPA-Cl was higher than in control subjects (2.62 +/- 0.25 versus 1.20 +/- 0.12 %/min; p less than 0.001). In the episodes of allograft lung rejection, DTPA-Cl increased to 3.65 +/- 0.41 %/min (p less than 0.02) as compared with episodes of normal lung histology. The change in DTPA-Cl during allograft lung rejection was correlated (r = 0.3, p less than 0.01) with the increased percentage of lymphocytes in bronchoalveolar lavage (27.8 +/- 3.5% in rejection versus 19.9 +/- 2.2% in normal histology; p less than 0.02). Sensitivity and specificity of DTPA-Cl measurement in detecting lung rejection were 69 and 82%, respectively, versus 45 and 85% for FEV1 measurement. These results suggest that DTPA-Cl monitoring could be used in conjunction with pulmonary function testing as a noninvasive approach for the detection of lung rejection.

Delayed temporary threshold shift induced by impulse noises (weapon noises) in men.

Most of the available information on the effects of impulse noise on hearing is derived from temporary threshold shift (TTS2) measurements performed 2 min after a single exposure to small-weapon noises. TTS is known to recover as a linear function of the logarithm of time when it is induced by a continuous noise of moderate intensity. Following the exposure to impulse noise, several investigators have reported individual exceptions to the log-time relation, e.g. increases in TTS during the first hour of recovery. These authors observed a 'rebound recovery function' for most of the exposed men, and they conclude that this phenomenon '... has implications for the use of TTS in the construction of damage risk criteria for hazardous noise exposure ..., a single measure, such as the widely used TTS2 may not be an adequate index of the magnitude of the TTS'. In order to thoroughly investigate in man the existence of 'delayed' TTS following the exposure to actual weapon noises, the 'French Committee on Weapon Noises' carried out the following study. Three groups of soldiers (28 subjects) wearing no hearing protection were exposed in the free field over 2 days to impulse noises produced by a rifle. Békésy audiograms were obtained from each subject just before the exposure, and at 5 min, 1 h and 4 h after exposure. All audiometric tests were carried out even when no TTS was observable in the first postexposure audiogram. A significant number of subjects showed a 'delayed TTS' and/or 'rebound recovery'. The maximum TTS was observed at 1 h after exposure, but the observation of a delayed recovery and a rebound recovery indicate that audiometric tests should be performed in all cases at least up to 4 h after the exposure. More detailed work is necessary to establish what changes may be necessary in the present damage risk criteria for impulse noises of a very high level.

[Anesthesia and intensive care for heart-lung transplantation]. / Anesthésie et réanimation pour transplantation coeur-poumons.

Since Shumway carried out the first successful heart-lung transplant (HLT) in Stanford in 1981, HLT has become a new therapeutic means for patients with end-stage pulmonary disease or arterial hypertension. However, it is still rarely carried out because of a lack of donors and the complexity of the surgery and postoperative course. This review described the criteria for proper donor and recipient selection, as well as the anaesthetic and postoperative management of HLT patients at Marie Lannelongue Hospital. The lack of suitable organ grafts results, at least in part, from improper donor management. Pulmonary oedema by fluid overloading and excessive haemodilution should be carefully prevented. Low doses of catecholamines and vasopressin maintain circulatory stability and convenient organ function. The indications for HLT (primary pulmonary hypertension, Eisenmenger's complex, and end-stage bronchopulmonary disease) are all characterized by severe pulmonary hypertension, hypoxaemia and cardiac failure. Careful anaesthetic induction is required to avoid circulatory collapse. Cardiopulmonary bypass (CPB) should be started early, so that mediastinal dissection may be carried out in satisfactory haemodynamic conditions. After unclamping the aorta, circulatory support with fluid and catecholamine infusion is often required. High inspired oxygen fraction and end-expiratory positive pressure may be required because of reperfusion pulmonary oedema. Blood transfusion is often needed as there are major blood losses due to dissection of the posterior mediastinum during CPB. Postoperative catecholamine administration is prolonged over several days. Negative fluid balance is often necessary to reduce pulmonary oedema. Improvement in surgical technique, early extubation, and late prescription of steroids have reduced the incidence of tracheal complications. Acute renal failure often occurs as a result of prolonged CPB, hypovolaemia, drug nephrotoxicity and sepsis. Bacterial complications (pneumonia, mediastinitis) are the main causes of early death. After the 15th postoperative day, opportunistic infections and allograft rejection are the main complications. Since 1981, major advances in HLT recipient management resulted in improved survival rates (70-80% at 1 year, and 60-70% at 2 years for the best teams). Despite the complexity of management, and the longterm threat of obliterative bronchiolitis, HLT is, at present time, the only possibility for these young patients to recover a normal quality of life.

[Heart-lung transplantation and double lung transplantation. 33 cases]. / Transplantations coeur-poumons et bipulmonaires. 33 cas.

Between June 1986 and October 1989, 29 heart lung transplantations and 4 double lung transplantations were performed at the Marie Lannelongue Hospital, Paris. The early and later course of these patients was studied. The actuarial survival rates at one and two years were 65 percent and 55 percent respectively. Bacterial infection was the main cause of early death. Late morbidity was predominantly due to cytomegalovirus infection and episodes of rejection. Respiratory function, evaluated in 19 long-term survivors, was usually normal. Only 3 patients developed a functional pattern of severe obliterative bronchiolitis probably related to uncontrolled rejections. The indications of the different types of lung transplantation are discussed: in cases of primary pulmonary hypertension or Eisenmenger's complex, heart lung transplantation is the only possible procedure. In patients with respiratory failure without cardiac dysfunction, double lung transplantation gives good functional results and makes an extra heart available for transplantation in another patient. Single lung transplantation, which gives worse functional results with a similar mortality rate, must be reserved for patients who are unable to undergo double lung transplantation.

The use of N-alkoxycarbonyl derivatives of 2-amino-2-deoxy-D-glucose as donors in glycosylation reactions.

1,3,4,6-Tetra-O-acetyl-2-alkoxycarbonylamino-2-deoxy-beta-D-glu copyranoses and 3,4,6-tri-O-acetyl-2-alkoxycarbonylamino-2-deoxy-alpha-D-glucopyra nosyl bromides have been used as donors in glycosylation reactions with model alcohols. beta-Glycosides were obtained in good yields and with a high degree of 1,2-trans stereoselectivity. An oxazolidinone was formed as the main product from the reaction of some of the glucopyranosyl bromides with alcohols of low reactivity, but the formation of all products could be interpreted by a strong participation of the alkoxycarbonylamino group.

Pulmonary arterial embolus by an unusual wandering bullet.

We report on a wandering bullet embolus to the left pulmonary artery after it had first passed from the right ventricular to the right renal vein via the inferior vena cava. Its presence in the left pulmonary artery was confirmed by pulmonary angiography. Hemorrhage due to the right ventricular wound was controlled by a median sternotomy and the bullet was extracted by left lateral thoracotomy. Intravascular migratory bullets continue to be a surgical curiosity. Clinical diagnosis may present a difficult aspect in emergency practice and angiography is mandatory. The removal of foreign bodies is recommended by the majority of authors.

[Cholecystectomy and colorectal adenocarcinoma]. / Colecistectomía y adenocarcinoma colorectal.

The relative risk of developing colorectal cancer after cholecystectomy was investigated retrospectively in 124 patients with colorectal cancer, 17 patients of which had undergone previous cholecystectomy. Another 124 patients without colorectal cancer were matched for sex and age; 19 patients of which had undergone previous cholecystectomy. Disregarding sex and cancer location the relative risk was 0.87 with a 90% confidential interval from 0.43 to 1.73. On the other hand considering cancer location the relative risk of suffering right-sided hemicolon cancer was 7 with a 90% confidential interval from 1.12 to 155.46 (P less than 0.05). The hypothesis that cholecystectomy increases the risk of suffering right-sided hemicolon adenocarcinoma however requires further evaluation.

Colecistectomia y adenocarcinoma colorectal. / Cholecystectomy and colorectal adenocarcinoma

El riesgo relativo a padecer de cancer colorectal despues de la colecistectomia, se investigo de manera retrospectiva en 124 pacientes con cancer intestinal, de los cuales 17 habian sido previamente colecistectomizados. El mismo numero de pacientes, sin cancer colorectal, se los apareo como controles segun edad y sexo, de los cuales 19 habian sido previamente colecistectomizados. El riesgo relativo sin discriminar sexo ni ubicacion del cancer fue de 0.87 con un intervalo confidencial del 90% de 0.43 a 1.73; en cambio al considerar la localizacion del cancer, el riesgo relativo para el cancer del H.D. fue de 7, con un intervalo confidencial del 90% de 1.12 a 155.46 (P < 0.05). La hipotesis que la colecistectomia aumente el riesgo a padecer de adenocarcinoma del hemicolon derecho necesita futuras investigaciones