Complete nucleotide sequence and identification of membrane components of the histidine transport operon of S. typhimurium

The nucleotide sequence of the entire histidine transport operon from Salmonella typhimurium has been determined and is shown to consist of four genes, hisJ, hisQ, hisM and hisP. This operon provides the only example of a binding protein-dependent transport system for which the total number of protein components is known. Determination of the amino acid compositions and sequences of these four transport proteins, together with analysis of various transport mutants, allows us to propose a molecular model for binding protein-dependent transport.

Survival in chronic hepatitis B. An analysis of 379 patients

Survival data from 379 patients with chronic hepatitis B were analyzed to determine life expectancy for the patient from the time of first contact. One hundred twenty-one patients had chronic persistent hepatitis, 128 had chronic active hepatitis, and 130 had chronic active hepatitis with cirrhosis. The frequency of symptoms (p less than 0.001), stigmata of chronic liver disease (p less than 0.001), and liver function test abnormalities (p less than 0.001) increased as the histologic features worsened, whereas the percentage of patients with circulating hepatitis B DNA polymerase declined (p less than 0.001). Women were uncommon in our series and had less severe disease than men (p less than 0.02). Fifty-one patients had died by the time of this analysis. The estimated 5-year survival rates were 97% for patients with chronic persistent hepatitis, 86% for those with chronic active hepatitis, and 55% for those with chronic active hepatitis with cirrhosis. The usual cause of death was liver failure and its sequelae. A multivariate analysis found age of 40 years or more, total bilirubin level of 1.5 mg/dL or more, ascites, and spider nevi to be factors that identified patients at a higher risk of death. The prognosis for patients with chronic hepatitis B is similar to that for patients with chronic hepatitis of other causes.

Characterization of SR 121463A, a highly potent and selective, orally active vasopressin V2 receptor antagonist

SR 121463A, a potent and selective, orally active, nonpeptide vasopressin V2 receptor antagonist, has been characterized in several in vitro and in vivo models. This compound displayed highly competitive and selective affinity for V2 receptors in rat, bovine and human kidney (0.6 < or = Ki [nM] < or = 4.1). In this latter preparation, SR 121463A potently antagonized arginine vasopressin (AVP)-stimulated adenylyl cyclase activity (Ki = 0.26+/-0.04 nM) without any intrinsic agonistic effect. In autoradiographic experiments performed in rat kidney sections, SR 121463A displaced [3H]AVP labeling especially in the medullo-papillary region and confirmed that it is a suitable tool for mapping V2 receptors. In comparison, the nonpeptide V2 antagonist, OPC-31260, showed much lower affinity for animal and human renal V2 receptors and lower efficacy to inhibit vasopressin-stimulated adenylyl cyclase (Ki in the 10 nanomolar range). Moreover, OPC-31260 exhibited a poor V2 selectivity profile and can be considered as a V2/V1a ligand. In normally hydrated conscious rats, SR 121463A induced powerful aquaresis after intravenous (0.003-0.3 mg/kg) or oral (0.03-10 mg/kg) administration. The effect was dose-dependent and lasted about 6 hours at the dose of 3 mg/kg p.o. OPC-31260 had a similar aquaretic profile but with markedly lower oral efficacy. The action of SR 121463A was purely aquaretic with no changes in urine Na+ and K+ excretions unlike that of known diuretic agents such as furosemide or hydrochlorothiazide. In addition, no antidiuretic properties have been detected with SR 121463A in vasopressin-deficient Brattleboro rats. Thus, SR 121463A is the most potent and selective, orally active V2 antagonist yet described and could be a powerful tool for exploring V2 receptors and the therapeutical usefulness of V2 blocker aquaretic agents in water-retaining diseases.

Polyphenols journey through blood-brain barrier towards neuronal protection

Age-related complications such as neurodegenerative disorders are increasing and remain cureless. The possibility of altering the progression or the development of these multifactorial diseases through diet is an emerging and attractive approach with increasing experimental support. We examined the potential of known bioavailable phenolic sulfates, arising from colonic metabolism of berries, to influence hallmarks of neurodegenerative processes. In silico predictions and in vitro transport studies across blood-brain barrier (BBB) endothelial cells, at circulating concentrations, provided evidence for differential transport, likely related to chemical structure. Moreover, endothelial metabolism of these phenolic sulfates produced a plethora of novel chemical entities with further potential bioactivies. Pre-conditioning with phenolic sulfates improved cellular responses to oxidative, excitotoxicity and inflammatory injuries and this attenuation of neuroinflammation was achieved via modulation of NF-κB pathway. Our results support the hypothesis that these small molecules, derived from dietary (poly)phenols may cross the BBB, reach brain cells, modulate microglia-mediated inflammation and exert neuroprotective effects, with potential for alleviation of neurodegenerative diseases.

Accelerated improvement of alcoholic liver disease with enteral nutrition

This prospective study compared the effects of tube-fed nutrition with those of a regular diet in alcoholic liver disease. The high prevalence of malnutrition in patients with alcoholic liver disease requires clarification of the benefits of aggressive nutritional support. Patients were randomly assigned a regular diet without or with tube-fed supplementation, delivering 1.5 g/kg protein and 167 kJ/kg daily. Comparisons of encephalopathy, antipyrine clearance, metabolic rate, and biochemical parameters were performed weekly for 4 weeks. Sixteen patients receiving enteral supplementation had antipyrine half-life (50% vs. 3% reduction), serum bilirubin (25% vs. 0% reduction), and median encephalopathy scores that improved more rapidly than those of controls. Initially, 15 controls did not consume adequate calories to meet measured resting energy expenditure. Aggressive nutritional intervention accelerated improvement in alcoholic liver disease. Adverse effects did not offset the demonstrated benefits of a 2-cal/mL, casein-based tube-fed supplement. These findings support the use of standard, casein-based solutions in the treatment of alcoholic liver disease and as the control condition for future studies.

DELICIOUS III: a multipurpose double imaging particle coincidence spectrometer for gas phase vacuum ultraviolet photodynamics studies

We present a versatile double imaging particle coincidence spectrometer operating in fully continuous mode, named DELICIOUS III, which combines a velocity map imaging device and a modified Wiley-McLaren time of flight momentum imaging analyzer for photoelectrons and photoions, respectively. The spectrometer is installed in a permanent endstation on the DESIRS vacuum ultraviolet (VUV) beamline at the French National Synchrotron Radiation Facility SOLEIL, and is dedicated to gas phase VUV spectroscopy, photoionization, and molecular dynamics studies. DELICIOUS III is capable of recording mass-selected threshold photoelectron photoion coincidence spectra with a sub-meV resolution, and the addition of a magnifying lens inside the electron drift tube provides a sizeable improvement of the electron threshold/ion mass resolution compromise. In fast electron mode the ultimate kinetic energy resolution has been measured at ΔE/E = 4%. The ion spectrometer offers a mass resolution--full separation of adjacent masses--of 250 amu for moderate extraction fields and the addition of an electrostatic lens in the second acceleration region allows measuring the full 3D velocity vector for a given mass with an ultimate energy resolution of ΔE/E = 15%, without sacrificing the mass resolution. Hence, photoelectron images are correlated both to the mass and to the ion kinetic energy and recoil direction, to access the electron spectroscopy of size-selected species, to study the photodissociation processes of state-selected cations in detail, or to measure in certain cases photoelectron angular distributions in the ion recoil frame. The performances of DELICIOUS III are explored through several examples including the photoionization of N2, NO, and CF3.

Survival of Listeria monocytogenes in milk during high-temperature, short-time pasteurization

Milk from cows inoculated with Listeria monocytogenes was pooled for 2 to 4 days and then heated at 71.7 to 73.9 degrees C for 16.4 s or at 76.4 to 77.8 degrees C for 15.4 s in a high-temperature, short-time plate heat exchanger pasteurization unit. L. monocytogenes was isolated from milk after heat treatment in six of nine pasteurization trials done at 71.7 to 73.9 degrees C and in none of three trials done at 76.4 to 77.8 degrees C. An average of 1.5 to 9.2 L. monocytogenes cells was seen in each milk polymorphonuclear leukocyte before heat treatment in 11 of 12 pasteurization trials. Noticeable degradation of leukocytes with intracellular listeria was detected in unpasteurized milk after 3 days of storage at 4 degrees C, and by 4 days of storage leukocytes had deteriorated to cellular debris, suggesting that holding unpasteurized milk refrigerated for 4 or more days would eliminate a protective effect leukocytes may provide for increasing heat resistance of L. monocytogenes. Results indicate that under the conditions of this study, L. monocytogenes can survive the minimum high-temperature, short-time treatment (71.7 degrees C, 15 s) required by the U.S. Food and Drug Administration for pasteurizing milk.

Early activation defects in T lymphocytes from aged mice

Aging affects both calcium signals and protein kinase cascades in mouse T lymphocytes. The decline in calcium signal development largely represents differences between naive and memory T cells; the latter are resistant to increases in calcium concentration, and are more common in aged mice. Aging leads to declines in phosphorylation of a wide range of substrates in T cells stimulated by either anti-CD3 antibodies or by substances, such as phorbol myristate acetate (PMA) or ionomycin, that act at intracellular sites, but some phosphoproteins respond only in old T cells, and others respond regardless of age. Tyrosine phosphorylation of the CD3 zeta chain declines with age, both in resting T cells and after activation, but the proportion of Zap-70 that is bound to CD3 zeta increases in T cells from old mice. Zap-70 function and phosphorylation of CD3 zeta-associated Zap-70 change only slightly after stimulation of T cells by anti-CD3 and anti-CD4, and are at similar levels in activated old and young T cells. Nonetheless, induction of Raf-1, MEK, and ERK kinase activity declines with age in CD4 T cells. The effect of aging on T-cell activation is not simply an overall decline in signal intensity, but a set of qualitative changes that differ among subsets and depend at least partly on the nature of the stimulus.

Pathobiology of pulmonary hypertension. The role of platelets and thrombosis

With the rare exceptions of PAH associated with antiphospholipid antibodies, genetic platelet dysfunction, or inherited deficiencies of antithrombotic pathways, the thrombotic lesions are secondary, but frequently occurring, in most cases of primary or secondary PAH. Pulmonary arterial hypertension is associated with thrombotic lesions and persistent vasoconstriction and structural remodeling of PA. Activated platelets interact with the PA wall and may contribute to the functional and structural alterations of pulmonary vessels by releasing vasoactive factors and mitogenic mediators.

Masitinib, a c-kit/PDGF receptor tyrosine kinase inhibitor, improves disease control in severe corticosteroid-dependent asthmatics

BACKGROUND

Masitinib is a tyrosine kinase inhibitor targeting stem cell factor receptor (c-kit) and platelet-derived growth factor (PDGF) receptor, which are expressed on several cell types including mast cells and bronchial structural cells, respectively. We hypothesized that c-kit and PDGF receptor inhibition may decrease bronchial inflammation and interfere with airway remodeling, which are crucial features of severe asthma.

OBJECTIVES

The primary endpoint was the percent change from baseline in oral corticosteroids after 16 weeks of treatment. Change in asthma control (asthma control questionnaire), exacerbation rate, pulmonary function tests, rescue medication requirement and safety were secondary endpoints.

METHODS

A 16-week randomized, dose-ranging (3, 4.5, and 6 mg/kg/day), placebo-controlled study was undertaken in 44 patients with severe corticosteroid-dependent asthma who remained poorly controlled despite optimal asthma management.

RESULTS

At 16 weeks of treatment, a comparable reduction in oral corticosteroids was achieved with masitinib and placebo (median reduction of -78% and -57% in the masitinib and placebo arms, respectively). Despite this similar reduction, the Asthma Control Questionnaire score was significantly better in the masitinib arm as compared to placebo with a reduction by 0.99 unit at week 16 (P < 0.001) vs 0.43 unit in the placebo arm. Masitinib therapy was associated with more transient skin rash and edema.

CONCLUSIONS

Masitinib, a c-kit and PDGF-receptor tyrosine kinase inhibitor, may represent an innovative avenue of treatment in corticosteroid-dependent asthma. These preliminary results warrant further long-term clinical studies in severe asthma

Failure to detect hepatitis C virus genome in human secretions with the polymerase chain reaction

Although hepatitis C infection has been clearly demonstrated to be transmitted through blood products or blood contamination, most cases of sporadic hepatitis C infection are unassociated with parenteral risk factors, and it is unclear how infection might be acquired by nonparenteral means. One potential mode of nonparenteral transmission is through body secretions. We used a highly sensitive and specific polymerase chain reaction assay to determine whether hepatitis C viral genomic RNA could be detected in secretions obtained from nineteen individuals with chronic hepatitis C virus infection. Although hepatitis C genomic RNA was found in all 19 sera, hepatitis C virus RNA was not detected in any samples of saliva, semen, urine, stool or vaginal secretions from these patients. Viral titers in serum ranged from 10(2) to 10(7) polymerase chain reaction units/ml. The sensitivity of our polymerase chain reaction assay indicates that, if hepatitis C virus were in secretions, it would be present in amounts less than 1 to 4 polymerase chain reaction units/ml. This contrasts with hepatitis B virus infection, in which serum titers frequently are in excess of 10(9) copies of hepatitis B genomes/ml. Body secretions have been found to contain up to 10(6) copies of hepatitis B genomes/ml. Our findings support seroepidemiological studies indicating that nonparenteral transmission of hepatitis C through secretions is uncommon and probably much less efficient than hepatitis B virus infection.

Synthetic peptide vaccine against Taenia solium pig cysticercosis: successful vaccination in a controlled field trial in rural Mexico

Taenia solium cysticercosis seriously affects human health when localised in the central nervous system (CNS) and causes great economic loss in pig husbandry in rural areas of endemic countries. Increasing the resistance to the parasite in the obligatory host pig may help in curbing transmission. Three synthetic peptides based on protein sequences of the murine parasite Taenia crassiceps, which had previously been shown to induce protection in mice against homologous challenge, were tested as a vaccine against T. solium cysticercosis in pigs. Vaccinated and unvaccinated piglets (240 in all) were distributed in pairs among the peasants' households of two rural villages in Mexico in which 14% of the native pigs were cysticercotic. Ten to twelve months later, the effect of vaccination was evaluated at necropsy. Vaccination decreased the total number of T. solium cysticerci (98.7%) and reduced the prevalence (52.6%). The natural challenge conditions used in this field trial strengthen the likelihood of successful transmission control to both pig and human through a large-scale pig vaccination program. We believe this is a major contribution in anticysticercosis vaccine development as these rather simple yet protective peptides are potentially more cost-effective to produce and less variable in results than antigens that are more complex.

Hepatocellular carcinoma in ground squirrels persistently infected with ground squirrel hepatitis virus

Although persistent infection with hepatitis B virus and woodchuck hepatitis virus has been associated with development of hepatocellular carcinoma in the host, little has been known of such an association with ground squirrel hepatitis virus (GSHV), which is closely related to the woodchuck virus. Colonies of GSHV-infected and -uninfected Beechey ground squirrels were observed for tumors for a period of 5 years. Tumors developed in seven squirrels after a minimum of 2.4 years of observation per animal; each of the seven animals was over 4 years old when the tumor was detected. The predominant type of tumor was hepatocellular carcinoma, which appeared in 2 of 28 GSHV-bearing animals studied and in 1 of 23 squirrels with antibody to the virus. No hepatocellular carcinoma appeared in 24 GSHV marker-free squirrels. Integrated GSHV DNA was found in the hepatocellular carcinoma tissue of the one carrier animal examined, paralleling the frequent findings of integrated hepatitis B and woodchuck hepatitis viral DNA in human and woodchuck hepatocellular carcinoma. Although the incidence of liver carcinoma reported here in carrier ground squirrels is neither as great as that in carrier woodchucks nor statistically different from the incidence in noncarrier squirrels, the data presented suggest that persistent infection with GSHV may also be associated with hepatocellular carcinoma.

Jejunostomy: techniques, indications, and complications

Jejunostomy is a surgical procedure by which a tube is situated in the lumen of the proximal jejunum, primarily to administer nutrition. There are many techniques used for jejunostomy: longitudinal Witzel, transverse Witzel, open gastrojejunostomy, needle catheter technique, percutaneous endoscopy, and laparoscopy. The principal indication for a jejunostomy is as an additional procedure during major surgery of the upper digestive tract, where irrespective of the pathology or surgical procedures of the esophagus, stomach, duodenum, pancreas, liver, and biliary tracts, nutrition can be infused at the level of the jejunum. It is also used in laparotomy patients in whom a complicated postoperatory recovery is expected, those with a prolonged fasting period, those in a hypercatabolic state, or those who will subsequently need chemotherapy or radiotherapy. As a sole procedure it is advised for neurologic and congenital illnesses, in geriatric patients who pose difficult care demands, and for patients with tumors of the head and neck. The complications seen with jejunostomy can be mechanical, infectious, gastrointestinal, or metabolic. The rate of technical complications of the Witzel longitudinal technique is 2.1%, for the transverse Witzel up to 6.6%, for the Roux-en-Y 21%, for open gastrojejunostomy from 2%, and for the needle catheter technique from 1.5% with 0.14% mortality. The percutaneous endoscopic procedures have as much as a 12% complication rate; no figures exist for laparoscopy. The complications are moderate and severe: tube dislocation, obstruction or migration of the tube, cutaneous or intraabdominal abscesses, enterocutaneous fistulas, pneumatosis, occlusion, and intestinal ischemia. The infectious complications are aspiration pneumonia and contamination of the diet. The gastrointestinal complications are diarrhea 2.3% to 6.8%, abdominal distension, colic, constipation, nausea, and vomiting. The metabolic complications are hyperglycemia 29%, hypokalemia 50%, water and electrolyte imbalance, hypophosphatemia, and hypomagnesemia. These complications are secondary to inadequate selection of nutrition relative to the characteristics of the patient, to inadequate management of the mixture, and to deficient clinical care. The ideal jejunostomy technique depends on the material resources but more importantly on the experience of the surgeon. The benefits of jejunostomy justify the risks.

Nonpeptide vasopressin receptor antagonists: development of selective and orally active V1a, V2 and V1b receptor ligands

The involvement of vasopressin (AVP) in several pathological states has been reported recently and the selective blockade of the different AVP receptors could offer new clinical perspectives. During the past few years, various selective, orally active AVP V1a (OPC-21268, SR49059 (Relcovaptan)), V2 (OPC-31260, OPC-41061 (Tolvaptan), VPA-985 (Lixivaptan), SR121463, VP-343, FR-161282) and mixed V1a/V2 (YM-087 (Conivaptan), JTV-605, CL-385004) receptor antagonists have been intensively studied in various animal models and have reached, Phase IIb clinical trials for some of them. For many years now, our laboratory has focused on the identification of nonpeptide vasopressin antagonists with suitable oral bioavailability. Using random screening on small molecule libraries, followed by rational SAR and modelization, we identified a chemical series of 1-phenylsulfonylindolines which first yielded SR49059, a V1a receptor antagonist prototype. This compound displayed high affinity for animal and human V1a receptors and antagonized various V1a AVP-induced effects in vitro and in vivo (intracellular [Ca2+] increase, platelet aggregation, vascular smooth muscle cell proliferation, hypertension and coronary vasospasm). We and others have used this compound to study the role of AVP in various animal models. Recent findings from clinical trials show a potential interest for SR49059 in the treatment of dysmenorrhea and in Raynaud's disease. Structural modifications and simplifications performed in the SR49059 chemical series yielded highly specific V2 receptor antagonists (N-arylsulfonyl-oxindoles), amongst them SR121463 which possesses powerful oral aquaretic properties in various animal species and in man. SR121463 is well-tolerated and dose-dependently increases urine output and decreases urine osmolality. It induces free water-excretion without affecting electrolyte balance in contrast to classical diuretics (e.g. furosemide and hydrochlorothiazide). Notably, in cirrhotic rats with ascites and impaired renal function, a 10-day oral treatment with SR121463 (0.5 mg/kg) totally corrected hyponatremia and restored normal urine excretion. This compound also displayed interesting new properties in a rabbit model of ocular hypertension, decreasing intraocular pressure after single or repeated instillation. Thus, V2 receptor blockade could be of interest in several water-retaining diseases such as the syndrome of inappropriate antidiuretic hormone secretion (SIADH), liver cirrhosis and congestive heart failure and deserves to be widely explored. Finally, further chemical developments in the oxindole family have led to the first specific and orally active V1b receptor antagonists (with SSR149415 as a representative), an awaited class of drugs with expected therapeutic interest mainly in ACTH-secreting tumors and various emotional diseases such as stress-related disorders, anxiety and depression. However, from the recently described tissue localization for this receptor, we could also speculate on other unexpected uses. In conclusion, the development of AVP receptor antagonists is a field of intensive pharmacological and clinical investigation. Selective and orally active compounds are now available to give new insight into the pathophysiological role of AVP and to provide promising drugs.

Effect of sulindac on sporadic colonic polyps

BACKGROUND/AIMS

We sought to determine in a double-blinded, placebo-controlled study if the nonsteroidal anti-inflammatory drug sulindac causes regression of sporadic colonic polyps. The impetus for this study is the profound regressive effect of sulindac on polyps in familial adenomatous polyposis.

METHODS

Asymptomatic patients undergoing routine screening flexible sigmoidoscopy were enrolled if they had polyps of < or = 1 cm in size. Of 162 patients screened, 22 patients were randomly enrolled to take 150 mg of sulindac twice daily, and 22 patients took a placebo. Treatment duration was 4 months and was followed by colonoscopy with removal of all polyps.

RESULTS

Four patients were dropped from the study (sulindac group) due to urosepsis (1 patient), heartburn (2 patients), and anemia (1 patient). Compliance (determined by monthly pill counting), mean age, and the effect of sulindac vs. placebo on polyp regression or size were not statistically different in the two treatment groups. Analysis of our data indicated that there is only a 0.8% chance that the probability of polyp regression with sulindac is as large as 50%.

CONCLUSIONS

Four months of treatment with sulindac does not result in a clinically significant regression of sporadic colonic polyps, although a small effect may not have been detected by the size of our study. Our data suggest that the biological response of sporadic and familial polyposis polyps to sulindac is different.

Fructose metabolism as a common evolutionary pathway of survival associated with climate change, food shortage and droughts

Mass extinctions occur frequently in natural history. While studies of animals that became extinct can be informative, it is the survivors that provide clues for mechanisms of adaptation when conditions are adverse. Here, we describe a survival pathway used by many species as a means for providing adequate fuel and water, while also providing protection from a decrease in oxygen availability. Fructose, whether supplied in the diet (primarily fruits and honey), or endogenously (via activation of the polyol pathway), preferentially shifts the organism towards the storing of fuel (fat, glycogen) that can be used to provide energy and water at a later date. Fructose causes sodium retention and raises blood pressure and likely helped survival in the setting of dehydration or salt deprivation. By shifting energy production from the mitochondria to glycolysis, fructose reduced oxygen demands to aid survival in situations where oxygen availability is low. The actions of fructose are driven in part by vasopressin and the generation of uric acid. Twice in history, mutations occurred during periods of mass extinction that enhanced the activity of fructose to generate fat, with the first being a mutation in vitamin C metabolism during the Cretaceous-Paleogene extinction (65 million years ago) and the second being a mutation in uricase that occurred during the Middle Miocene disruption (12-14 million years ago). Today, the excessive intake of fructose due to the availability of refined sugar and high-fructose corn syrup is driving 'burden of life style' diseases, including obesity, diabetes and high blood pressure.

Allograft rejection after liver transplantation for autoimmune liver diseases

Autoimmune liver diseases (AILD) may progress to liver failure, requiring liver transplantation as definitive therapy, and these immune-mediated disorders may predispose the patient to more frequent graft rejection. The objective of this study was to determine the effect of preexisting AILD on the incidence of allograft rejection after liver transplantation. Sixty-three patients who underwent liver transplantation between March 1988 and December 1994 for AILDs that included autoimmune hepatitis (AIH; n = 33) and primary biliary cirrhosis (PBC; n = 30) were retrospectively compared with 47 patients who underwent liver transplantation for alcoholic cirrhosis during the same time period. There was a lower incidence of acute allograft rejection in patients with AILD who received tacrolimus-based compared with cyclosporine-based immunosuppression (50% v 85.5%; P = .02). However, patients with AILDs overall had a higher incidence of acute rejection than patients with alcoholic cirrhosis (81% v 46.8%; P < .001), regardless of the type of immunosuppression. In addition, steroid-resistant rejection occurred more frequently in patients with AILDs than in patients with alcoholic cirrhosis (38.1% v 12.8%; P = .003). There was also a trend toward a higher incidence of chronic rejection in patients with AILDs compared with patients with alcoholic cirrhosis (11.1% v 2.1%), but this difference did not reach statistical significance. Patient and graft survivals at 1 and 3 years were similar between patients with AILDs and alcoholic liver disease. Compared with alcoholic cirrhosis, preexisting AILDs are associated with a higher incidence of acute allograft rejection and a trend toward more frequent chronic rejection.

Adenine arabinoside monophosphate (vidarabine phosphate) in combination with human leukocyte interferon in the treatment of chronic hepatitis B. A randomized, double-blinded, placebo-controlled trial

STUDY OBJECTIVE

To determine the efficacy of adenine arabinoside monophosphate (Ara-AMP vidarabine phosphate) with or without human leukocyte interferon in chronic hepatitis B.

STUDY DESIGN

Randomized, double-blinded, placebo-controlled trial with 6-month treatment and an 18-month follow-up.

SETTING

Referral-based liver-disease clinics at three university medical centers.

PATIENTS

Twenty-five patients with chronic active hepatitis or cirrhosis and 39 with chronic persistent hepatitis.

INTERVENTIONS

Thirteen patients received intramuscular Ara-AMP, 2.5 mg/kg body weight, twice daily, alternated monthly for 6 months with subcutaneous human leukocyte interferon, 5 million units, twice daily. Painful paresthesia of the legs necessitated dosage reduction and early discontinuation of enrollment. Twenty-four patients received intramuscular Ara-AMP, 2.5 mg/kg, twice daily, alternated monthly for 6 months with a matching placebo given subcutaneously twice daily. Twenty-seven patients received placebo by intramuscular and subcutaneous injections twice daily for 6 months.

MEASUREMENTS AND MAIN RESULTS

Of the 64 patients, 95% had symptomatic and virologic data available and 64% had biopsies at 12 months; at 24 months, 77% had data available and 56% had repeat biopsies. The highest dropout rate was seen in the group receiving Ara-AMP. The group receiving the placebo was less symptomatic (Karnofsky score of 96% compared with 91% in the group receiving Ara-AMP/placebo and 92% in the group receiving Ara-AMP/human leukocyte interferon, p = 0.02) at 12 but not at 24 months. Loss of DNA polymerase, the hepatitis B e antigen, and the serum hepatitis B virus DNA was similar in all three groups. Histologically, erosion of the limiting plate and lobular activity favored Ara-AMP at 12 but not at 24 months and these differences did not result in differences in the histologic diagnosis.

CONCLUSION

These results do not support the use of Ara-AMP and human leukocyte interferon in chronic persistent or chronic active hepatitis B.

A prospective evaluation of thoracoscopy for the diagnosis of penetrating thoracoabdominal trauma

Penetrating thoracoabdominal trauma presents a difficult diagnostic dilemma. Violation of the diaphragm may be very difficult to establish. Conventional diagnostic procedures such as chest radiography, computed tomography, and diagnostic peritoneal lavage have been shown to be unreliable. Mandatory exploratory celiotomy carries a 20%-30% negative rate. Twenty-eight patients with penetrating thoracoabdominal trauma over a 6-month period were prospectively evaluated by thoracoscopy at a major urban trauma center. All patients were hemodynamically stable, had no indications for immediate celiotomy, and demonstrated thoracic injury on chest radiography or physical examination. All thoracoscopy was performed in the operating room under general anesthesia. Patients consisted of 25 males and 3 females with an age range of 15-48 years. Mechanism of injury consisted of 24 stab wounds and 4 gunshot wounds. Twelve of the procedures were for right chest wounds and 16 involved the left hemithorax. Diaphragmatic injury was identified at thoracoscopy in 9 patients (32%), with all confirmed and repaired at celiotomy. Eight of 9 patients (89%) undergoing celiotomy were found to have significant intra-abdominal injuries requiring surgical repair. Thoracoscopy was also useful for evacuation of blood from the pleural space. There were no procedure-related complications. Thoracoscopy is a safe, accurate, reliable diagnostic technique for evaluating thoracoabdominal penetrating trauma. It is less invasive than celiotomy and has the added benefit of diagnosis and therapy of the intrathoracic injuries.

A new target for shigellosis: rational design and crystallographic studies of inhibitors of tRNA-guanine transglycosylase

Eubacterial tRNA-guanine transglycosylase (TGT) is involved in the hyper-modification of cognate tRNAs leading to the exchange of G34 at the wobble position in the anticodon loop by preQ1 (2-amino-5-(aminomethyl)pyrrolo[2,3-d]pyrimidin-4(3H)-one) as part of the biosynthesis of queuine (Q). Mutation of the tgt gene in Shigella flexneri results in a significant loss of pathogenicity of the bacterium, revealing TGT as a new target for the design of potent drugs against Shigellosis. The X-ray structure of Zymomonas mobilis TGT in complex with preQ1 was used to search for new putative inhibitors with the computer program LUDI. An initial screen of the Available Chemical Directory, a database compiled from commercially available compounds, suggested several hits. Of these, 4-aminophthalhydrazide (APH) showed an inhibition constant in the low micromolar range. The 1.95 A crystal structure of APH in complex with Z. mobilis TGT served as a starting point for further modification of this initial lead.

A randomized non-crossover study comparing the ProSeal™ and Classic™ laryngeal mask airway in anaesthetized children

BACKGROUND

We tested the hypothesis that ease of insertion, oropharyngeal leak pressure, fibreoptic position, gastric insufflation, and the frequency of mucosal trauma differ between the ProSeal laryngeal mask airway (PLMA) and the classic laryngeal mask airway (cLMA) in anaesthetized children. For the PLMA, we also assessed the ease of gastric tube placement via the PLMA drain tube and measure residual gastric volume.

METHODS

240 consecutive ASA I-III children aged 1-16 yr were randomized for airway management with the ProSeal or cLMA.

RESULTS

The time taken to provide an effective airway, the number of insertion attempts, fibreoptic position of the airway tube and frequency of mucosal trauma were similar, but oropharyngeal leak pressure was higher (33 vs 26 cm H(2)O, P<0.0001) and gastric insufflation less common (0 vs 6%, P<0.01) for the PLMA. Gastric tube insertion was successful at the first attempt in 106 of 120, and at the second attempt in 14 of 120. The mean (sd; range) value for residual gastric volume was 2.2 (5.9; 0-30) ml. There were no differences in performance among sizes for the PLMA and the cLMA.

CONCLUSIONS

We conclude that ease of insertion, fibreoptic position, and frequency of mucosal trauma are similar for the PLMA and cLMA in children, but oropharyngeal leak pressure is higher and gastric insufflation less common for the PLMA. Gastric tube insertion has a high success rate, provided the PLMA is correctly positioned.

tRNA-guanine transglycosylase from Escherichia coli: gross tRNA structural requirements for recognition

tRNA-guanine transglycosylase (TGT) is the enzyme responsible for the post-transcriptional modification of specific tRNAs (those for Asn, Asp, His, and Tyr) with the hypermodified base, queuine. In Escherichia coli this enzyme catalyzes the exchange of guanine-34 in the anticodon with preQ1, which is subsequently further modified to queuine. There is evidence that such hypermodified tRNA molecules may play a role in the control of cell proliferation and differentiation. In order to perform detailed, in vitro mechanistic studies and to probe the tRNA-enzyme interaction, we have generated unmodified E. coli tRNA(Tyr) and truncated analogues using an in vitro RNA synthesis system suggested by Milligan and Uhlenbeck [Milligan, J. F., & Uhlenbeck, O. C. (1989) Methods Enzymol. 180, 51-62]. From this system we have generated three tRNA analogues totally devoid of any post-transcriptional modifications. In order to compare the unmodified tRNA with the true physiological substrate for TGT, that is, tRNA that contains all modified bases except queuine, we have isolated E. coli tRNA(Tyr) from an overexpressing clone in a TGT-deficient strain of E. coli. We report here that unmodified, full-length tRNA(Tyr) serves as a substrate for TGT with kinetic parameters that are, within experimental error, the same as those for in vivo isolated tRNA(Tyr). This indicates that other post-transcriptional modifications have negligible effects upon TGT recognition of tRNA. A 17-base oligoribonucleotide, corresponding to the anticodon loop and stem, is also a substrate for TGT with only a 20-fold loss in Vmax/KM, versus the full-length tRNA.(ABSTRACT TRUNCATED AT 250 WORDS)