The evolution of percutaneous nephrolithotomy: Analysis of a single institution experience over 25 years

INTRODUCTION

Over time, the incidence of nephrolithiasis has risen significantly, and patient populations have become increasingly complex. Our study aimed to determine the impact of changes in patient demographics on percutaneous nephrolithotomy (PCNL) outcomes.

METHODS

A retrospective analysis of a prospectively collected database was carried out from 1990-2015. Patient demographics, comorbidities, stone and procedure characteristics were analyzed. Multivariate logistic regression was used to evaluate differences in operative duration, complications, stone-free rate, and length of stay.

RESULTS

A total of 2486 patients with a mean age of 54±15 years, body mass index (BMI) of 31±8, and stone surface area of 895±602 mm² were analyzed; 47% of patients had comorbidities, including hypertension (22%), diabetes mellitus (14%), and cardiac disease (13%). Complication rate was 19%, including a 2% rate of major complications (Clavien grade III-V). There was a statistically significant increase in patient age, BMI, and comorbidities over time, which was correlated with an increased complication rate (odds ratio [OR] 1.15; p=0.010). The overall transfusion rate was 1.0% and remained stable (p=0.131). With time, both OR duration (mean Δ 16 minutes; p<0.001) and hospital length of stay (mean Δ 2.4 days; p<0.001) decreased significantly. Stone-free rate of 1873 patients with available three-month followup was 87% and decreased significantly over time (OR 1.09; p<0.001), but was correlated with an increased use of computed tomography (CT) scans for followup imaging.

CONCLUSIONS

Despite an increasingly complex patient population, PCNL remains a safe and effective procedure with a high stone-free rate and low risk of complications.

Transplantation of pediatric renal allografts from donors less than 10 kg

Few transplant programs use kidneys from donors with body weight (BW) < 10 kg. We hypothesized that pediatric en bloc transplants from donors with BW < 10 kg would provide similar transplant outcomes to larger grafts. All pediatric en bloc renal transplants performed at our center between 2001 and 2017 were reviewed (N = 28). Data were stratified by smaller (donor BW < 10 kg; n = 11) or larger donors (BW > 10 kg; n = 17). Renal volume was assessed during follow-up with ultrasound. Demographic characteristics were similar between the 2 groups of recipients. After mean follow-up of 44 months (smaller donors) and 124 months (larger donors), graft and patient outcomes were similar between groups. Serum creatinine at 1, 3, and 5 years was no different between groups. At 1 day posttransplant, mean total renal volume in the smaller donors was 28 ± 9 mm³ vs 45 ± 12 mm³ (P < .01). By 3 weeks, it was 53 ± 19 mm³ (smaller donors) versus 73 ± 19 mm³ (larger donors) (P = NS). Complication rates were similar between both groups with 1 case of venous thrombosis in the smaller group. With experience, outcomes are equivalent to those from larger pediatric donors.

KIM-1 Is a Potential Urinary Biomarker of Obstruction: Results from a Prospective Cohort Study

INTRODUCTION

Partial or complete obstruction of the urinary tract is a common and challenging urological condition that may occur in patients of any age. Serum creatinine is the most commonly used method to evaluate global renal function, although it has low sensitivity for early changes in the glomerular filtration rate or unilateral renal pathology. Hence, finding another measurable parameter that reflects the adaptation of the renal physiology to these circumstances is important. Several recent studies have assessed the use of new biomarkers of acute kidney injury (AKI), but the information among patients with stone disease and those with obstructive uropathy is limited.

MATERIAL AND METHODS

A prospective cohort study was conducted to determine the urinary levels of kidney injury molecule-1 (KIM-1), Total and Monomeric neutrophil gelatinase-associated lipocalin (NGAL) in patients with hydronephrosis secondary to renal stone disease, congenital ureteropelvic junction obstruction or ureteral stricture. Comparison between patients with hydronephrosis and no hydronephrosis was carried out along with correlation analysis to detect factors associated with biomarker expression.

RESULTS

Urinary levels of KIM-1 significantly decreased after hydronephrosis treatment in patients with unilateral obstruction (1.19 ng/mL vs 0.76 ng/mL creatinine, p = 0.002), additionally KIM-1 was significantly higher in patients with hydronephrosis compared to stone disease patients without radiological evidence of obstruction (1.19 vs 0.64, p = 0.006). Total and Monomeric NGAL showed a moderate correlation with the presence of leukocyturia. We found that a KIM-1 value of 0.735 ng/mg creatinine had a sensitivity of 75% and specificity of 67% to predict the presence of hydronephrosis in preoperative studies (95% CI 0.58-0.87, p = 0.006).

CONCLUSION

Our results show that KIM-1 is a promising biomarker of subclinical AKI associated with hydronephrosis in urological patients. NGAL values were influenced by the presence of leukocyturia, limiting its usefulness in this population.

Assessing the Magnitude of Effect of Bone Structures on Shockwave Lithotripsy Fragmentation: Results from an In Vitro Study

INTRODUCTION

Several anatomic and clinical factors have been implicated in the failure rates of shock wave lithotripsy (SWL), including the attenuating effects of bony structures. We designed an in vitro model that incorporates the lumbar spine, including vertebral bodies and transverse processes along the pathway of shockwaves, to mimic the clinical scenario during SWL of upper ureteral stones. We hypothesized that the presence of bone structures in the SWL pathway significantly affects the fragmentation rate.

MATERIALS AND METHODS

An ordnance gelatin (OG) model was conceptualized and created to allow a pig's lumbar spine to be embedded within it. Artificial urinary calculi weighing 2 ± 0.1 g (1.2-cm diameter) were prepared using BegoStone plaster. The trial was divided into two arms: group 1 models had OG only and served as the control and group 2 models had the bone embedded in the gelatin with stone wells placed above the transverse processes. Twenty-four stones per group were subjected to SWL using the STORZ MODULITH SLX-F2 lithotripter, using the same treatment parameters. Fragments were sieved through 2- and 4-mm filters, and the fragmentation coefficients (FC) were calculated. The Mann-Whitney test was used to compare FC between the two groups.

RESULTS

The mean fragmentation rate of group 1 was statistically significantly higher compared with group 2 using a 4-mm sieve (43% vs 0.62%, p < 0.001) and the 2-mm filter (18% vs 0.52%, p < 0.001).

CONCLUSIONS

The presence of bone structures dramatically reduces the fragmentation rate of phantom stones using an OG in vitro model. The OG model is inexpensive and simple to use to simulate clinical situations during SWL.

Robotic Proximal Ureteropyelostomy After Unsuccessful Endourologic Management of Complicated Proximal Ureteral Stone Disease

We present a clinical case of a 66-year-old female with a left ureteropelvic junction impacted renal calculi associated with a tortuous ureter. After a failed combined retrograde and antegrade endoscopic procedure, a robot-assisted laparoscopic ureteropyelostomy was successful.

Cost analysis of two follow-up strategies for localized kidney cancer: a Canadian cohort comparison

Introduction: The cost of surveillance strategies in patients afterradical nephrectomy for localized primary renal cell carcinoma(RCC) has not been evaluated. We compared the costs of 2 differentsurveillance strategies, the new Canadian Urological Association(CUA) guidelines and the old strategy implemented in our institution. Methods: Seventy-five patients who underwent radical nephrectomyfor primary non-metastatic renal cancer were retrospectivelyreviewed. The direct cost of surveillance was determined and comparedwith the theoretical cost which would have been accruedusing the CUA guidelines. Results: Our mean follow-up was 31.1 (SD ± 20.4) months. Theoverall and disease-free survival endpoints were 87.7% and 85.2%,respectively. Total medical costs were higher for our old institutionalsurveillance strategy than the CUA guidelines ($181 861vs. $135 054). For the complete follow-up of 75 patients, a costsavingsof $46 806 could have been achieved following the CUAguidelines (p = 0.002). Of recurrences, 7 of 8 were detected by routinescreening, only 1 recurrence was identified by symptoms. Thecost per recurrence detected in our old protocol was $9 812.92.The increased cost of our institution was due to more visits withbasic testing, symptomatic investigation, and follow-up of imagingtests. The median percent cost attributable to these extra tests was15% (range 0 to 59). Conclusion: Based on our results, we endorse the new CUA surveillancestrategy in RCC follow-up as appropriate and cost effective incomparison with previous follow-up strategies used at our institution.Can Urol Assoc J 2010;4(5):322-326Introduction : Le coût associé aux stratégies de surveillance despatients ayant subi une néphrectomie radicale en raison d’un hypernéphromeprimitif localisé n’a jamais été évalué. Nous avons comparéles coûts de deux stratégies de surveillance différentes, soitles nouvelles lignes directrices de l’Association des urologues duCanada (AUC) et l’ancienne stratégie utilisée à notre établissement. Méthodologie : Soixante-quinze patients qui ont subi une néphrectomieradicale en raison d’un néphrome primitif non métastatiqueont été passés en revue de façon rétrospective. Les coûts directs dela surveillance ont été déterminés et comparés avec le coût théoriquequi aurait été comptabilisé en suivant les lignes directrices de l’AUC. Résultats : La durée moyenne du suivi était de 31,1 mois (ÉT ± 20,4).La survie globale et la survie sans maladie étaient de 87,7 % et 85,2%, respectivement. Les coûts médicaux totaux étaient plus élevés avecl’ancienne stratégie de surveillance de notre établissement par rapportaux lignes directrices de l’AUC (181 861 $ contre 135 054 $). Deséconomies de 46 806 $ auraient pu être réalisées en suivant leslignes directrices de l’AUC pour le suivi complet des 75 patients(p = 0,002). Quant aux récurrences, 7 sur 8 ont été décelées lorsde tests de routine, et une seule a été décelée par la présence desymptômes. Le coût d’une récurrence décelée selon notre ancienprotocole était de 9 812,92 $. Le coût plus élevé lié au protocole denotre établissement est attribuable à un nombre plus élevé de visitesavec épreuves de routine, vérification des symptômes et suivi desépreuves d’imagerie. Le pourcentage médian du coût attribuable àces épreuves supplémentaires était de 15 % (0 à 59 %). Conclusion : En fonction de nos résultats, nous appuyons la nouvellestratégie de surveillance de l’AUC pour le suivi des casd’hypernéphrome; cette stratégie nous semble approprié et rentableen comparaison avec les stratégies auparavant utilisées à notre

Cost analysis of two follow-up strategies for localized kidney cancer: a Canadian cohort comparison

INTRODUCTION

The cost of surveillance strategies in patients after radical nephrectomy for localized primary renal cell carcinoma (RCC) has not been evaluated. We compared the costs of 2 different surveillance strategies, the new Canadian Urological Association (CUA) guidelines and the old strategy implemented in our institution.

METHODS

Seventy-five patients who underwent radical nephrectomy for primary non-metastatic renal cancer were retrospectively reviewed. The direct cost of surveillance was determined and compared with the theoretical cost which would have been accrued using the CUA guidelines.

RESULTS

Our mean follow-up was 31.1 (SD ± 20.4) months. The overall and disease-free survival endpoints were 87.7% and 85.2%, respectively. Total medical costs were higher for our old institutional surveillance strategy than the CUA guidelines ($181 861 vs. $135 054). For the complete follow-up of 75 patients, a cost-savings of $46 806 could have been achieved following the CUA guidelines (p = 0.002). Of recurrences, 7 of 8 were detected by routine screening, only 1 recurrence was identified by symptoms. The cost per recurrence detected in our old protocol was $9 812.92. The increased cost of our institution was due to more visits with basic testing, symptomatic investigation, and follow-up of imaging tests. The median percent cost attributable to these extra tests was 15% (range 0 to 59).

CONCLUSION

Based on our results, we endorse the new CUA surveillance strategy in RCC follow-up as appropriate and cost effective in comparison with previous follow-up strategies used at our institution.

A density functional for sparse matter

Sparse matter is abundant and has both strong local bonds and weak nonbonding forces, in particular nonlocal van der Waals (vdW) forces between atoms separated by empty space. It encompasses a broad spectrum of systems, like soft matter, adsorption systems and biostructures. Density-functional theory (DFT), long since proven successful for dense matter, seems now to have come to a point, where useful extensions to sparse matter are available. In particular, a functional form, vdW-DF (Dion et al 2004 Phys. Rev. Lett. 92 246401; Thonhauser et al 2007 Phys. Rev. B 76 125112), has been proposed for the nonlocal correlations between electrons and applied to various relevant molecules and materials, including to those layered systems like graphite, boron nitride and molybdenum sulfide, to dimers of benzene, polycyclic aromatic hydrocarbons (PAHs), doped benzene, cytosine and DNA base pairs, to nonbonding forces in molecules, to adsorbed molecules, like benzene, naphthalene, phenol and adenine on graphite, alumina and metals, to polymer and carbon nanotube (CNT) crystals, and hydrogen storage in graphite and metal-organic frameworks (MOFs), and to the structure of DNA and of DNA with intercalators. Comparison with results from wavefunction calculations for the smaller systems and with experimental data for the extended ones show the vdW-DF path to be promising. This could have great ramifications.

van der Waals density functional for general geometries

A scheme within density functional theory is proposed that provides a practical way to generalize to unrestricted geometries the method applied with some success to layered geometries [Phys. Rev. Lett. 91, 126402 (2003)]]. It includes van der Waals forces in a seamless fashion. By expansion to second order in a carefully chosen quantity contained in the long-range part of the correlation functional, the nonlocal correlations are expressed in terms of a density-density interaction formula. It contains a relatively simple parametrized kernel, with parameters determined by the local density and its gradient. The proposed functional is applied to rare gas and benzene dimers, where it is shown to give a realistic description.

Van der Waals density functional for layered structures

To understand sparse systems, we must account for both strong local atom bonds and weak nonlocal van der Waals forces between atoms separated by empty space. A fully nonlocal functional form [Phys. Rev. B 62, 6997 (2000)]] of density-functional theory (DFT) is applied here to the layered systems graphite, boron nitride, and molybdenum sulfide to compute bond lengths, binding energies, and compressibilities. These key examples show that the DFT with the generalized-gradient approximation does not apply for calculating properties of sparse matter, while use of the fully nonlocal version appears to be one way to proceed.

Identification by saturation mutagenesis of a single residue involved in the alpha-galactosidase AgaB regioselectivity

The alpha-galactosidase AgaB of Bacillus stearothermophilus displays a major 1,6 and a minor 1,3 regioselectivity. The wild-type enzyme was subjected to directed evolution (random mutagenesis and in vitro recombination) using a double screening strategy based on the elimination of the 1,6 regioselectivity and the analysis by TLC of the transglycosylation products. One of the AgaB mutants (E500) exhibited a new 1,2 regioselectivity and a rather high level of transglycosylation. The corresponding gene contains 10 mutations compared to the agaB gene and we demonstrated by saturation mutagenesis that the G442R substitution strongly contributes to the emergence of this new regioselectivity. Moreover, other single point mutations at this position led to new mutants displaying other kinds of regioselectivity demonstrating the importance of this position in the subtle kinetic control of transglycosylation.

Modulation of the regioselectivity of a Bacillus alpha-galactosidase by directed evolution

Alpha-galactosidase AgaB of Bacillus stearothermophilus was subjected to directed evolution in an effort to modify its regioselectivity. The wild-type enzyme displays a major 1,6 and minor 1,3 regioselectivity. We used random mutagenesis and staggered extension process (StEP) to obtain mutant enzymes displaying modified regioselectivity. We developed a screening procedure allowing first the elimination of AgaB mutants bearing the 1,6 regioselectivity and secondly the selection of those retaining a 1,3 regioselectivity. Our results show that, among the evolved enzymes that have lost most of their activity towards the 1,6 linkage both in hydrolysis and in synthesis, one (E901) has retained its 1,3 activity. However the transglycosylation level reached by this mutant is quite low versus that of the native enzyme. This work constitutes the first example of modification of glycosylhydrolase regioselectivity by directed evolution.

Comparative study of new alpha-galactosidases in transglycosylation reactions

We have studied the potential of several newly cloned alpha-galactosidases to catalyze the regioselective synthesis of disaccharides using 4-nitrophenylgalactoside as a donor. The kinetics of the reactions were followed by in situ NMR spectroscopy. The following thermophilic enzymes have been tested: Aga A and an isoenzyme Aga B obtained from the strain KVE39 and Aga 285 from the strain IT285 of Bacillus stearothermophilus; Aga T is an alpha-galactosidase from Thermus brockianus (strain IT360). Two other non-thermophilic alpha-galactosidases have also been evaluated: Aga 1 (Streptococcus mutans, strain Ingbritt) and Raf A (Escherichia coli, strain D1021). For all of the enzymes studied, high regioselectivity was observed leading to two (1 --> 6)-disaccharides: 4-nitrophenyl alpha-D-galactopyranosyl-(1--> 6)-alpha-D-galactopyranoside and methyl alpha-D-galactopyranosyl-(1--> 6)-alpha-D-galactopyranoside, which were obtained in 54% (Aga B) and 20% (Aga T) yields, respectively.

Kinetic study of a thermostable beta-glycosidase of Thermus thermophilus. Effects of temperature and glucose on hydrolysis and transglycosylation reactions

A beta-glycosidase of a thermophile, Thermus thermophilus, belonging to the glycoside hydrolase family 1, was cloned and overexpressed in Escherichia coli. The purified enzyme (Ttbetagly) has a broad substrate specificity towards beta-D-glucoside, beta-D-galactoside and beta-D-fucoside derivatives. The thermostability of Ttbetagly was exploited to study its kinetic properties within the range 25-80 degreesC. Whatever the temperature, except around 60 degreesC, the enzyme displayed non-Michaelian kinetic behavior. Ttbetagly was inhibited by high concentrations of substrate below 60 degreesC and was activated by high concentrations of substrate above 60 degreesC. The apparent kinetic parameters (kcat and Km) were calculated at different temperatures. Both kcat and Km increased with an increase in temperature, but up to 75 degreesC the values of kcat increased much more rapidly than the values of Km. The observed kinetics might be due to a combination of factors including inhibition by excess substrate and stimulation due to transglycosylation reactions. Our results show that the substrate could act not only as a glycosyl donor but also as a glycosyl acceptor. In addition, when the glucose was added to reaction mixtures, inhibition or activation was observed depending on both substrate concentration and temperature. A reaction model is proposed to explain the kinetic behavior of Ttbetagly. The scheme integrates the inhibition observed at high concentrations of substrate and the activation due to transglycosylation reactions implicating the existence of a transfer subsite.

Eye muscle nerves nuclear size in a breed of domestic rabbits with floppy ears

In many wild species there is a correlation between the capacity for directional hearing and directional seeing, which is associated with the mobility of the eye balls. Among the breeds of domestic rabbits, there are some with pendulous, floppy external ears (e.g., Englische Widder, EW) that might limit directional hearing. The size of the brain stem nuclei in EWs has been determined and compared to rabbits with upright ears. In EW, the oculomotor nuclei are relatively larger than in the other breeds. Possibly, this indicates a compensation of a loss in directional hearing ability achieved through greater mobility of the eyes. At the same time, a variability of brain composition between the breeds, which is an intraspecific variability, is obvious.

Cloning and expression of a beta-glycosidase gene from Thermus thermophilus. Sequence and biochemical characterization of the encoded enzyme

A 3.2 kilobase pair DNA fragment from Thermus thermophilus HB27 coding for a beta-galactosidase activity was cloned and sequenced. A gene and a truncated open reading frame orf1 encoding respectively a beta-glycosidase (ttbeta-gly) and probably a sugar permease were located directly adjacent to each other. The deduced aminoacid sequence of the enzyme Ttbeta-gly showed strong identity with those of beta-glycosidases belonging to the glycosyl hydrolase family 1. The enzyme was overexpressed in Escherichia coli and was purified by a two-step purification procedure. The recombinant enzyme is monomeric with a molecular mass of 49-kDa. It catalyzes the hydrolysis of beta-D-galactoside, beta-D-glucoside and beta-D-fucoside derivatives. However, the kcat/Km ratio is much higher for p-nitrophenyl-beta-D-glucoside and p-nitrophenyl-beta-D-fucoside than for p-nitrophenyl-beta-D-galactoside. The specificity towards linkage positions of the disaccharides tested decreased in the following order: beta1-3 (100%) > beta1-2 (71%) > beta1-4 (40%) > beta1-6 (10%). Ttbeta-gly is a thermostable enzyme displaying an optimum temperature of 88 degrees C and a half life of 10 min at 90 degrees C. It performs transglycosylation reactions at high temperature with a yield exceeding 63% for transfucosylation reactions. On the basis of this work, the enzyme appears to be an attractive tool in the synthesis of fucosyl adducts and fucosyl sugars.

The highly thermostable arginine repressor of Bacillus stearothermophilus: gene cloning and repressor-operator interactions

We report here the cloning of the arginine repressor gene argR of Bacillus stearothermophilus and the characterization and purification to homogeneity of its product. The deduced amino acid sequence of the 16.8-kDa ArgR subunit shares 72% identity with its mesophilic homologue AhrC of Bacilus subtilis. Sequence analysis of B. stearothermophilus ArgR and comparisons with mesophilic arginine repressors suggest that the thermostable repressor comprises an N-terminal DNA-binding and a C-terminal oligomerization and arginine-binding region. B. stearothermophilus ArgR has been overexpressed in E. coli and purified as a 48.0-kDa trimeric protein. The repressor inhibits the expression of a B. stearothermophilus argC-lacZ fusion in E. coli cells. In the presence of arginine, the purified protein binds tightly and specifically to the argC operator, which largely overlaps the argC promoter. The purified B. stearothermophilus repressor proved to be very thermostable with a half-life of approximately 30 min at 90 degrees C, whereas B. subtilis AhrC was largely inactivated at 65 degrees C. Moreover, ArgR operator complexes were found to be remarkably thermostable and could be formed efficiently at up to 85 degrees C, well above the optimal growth temperature of the moderate thermophile B. stearothermophilus. This pronounced resistance of the repressor-operator complexes to heat treatment suggests that the same type of regulatory mechanism could operate in extreme thermophiles.

Detection of a homologue of bcl-2 in plant cells

An emerging family of bcl-2-like genes has been identified from nematode to humans. These genes play a role in the maintenance of homeostasis. Its members have highly conserved domains that are important for their dimerization. Since nothing is known about the importance of these genes in plant cells, we have investigated their presence in an alga as well as in three higher plants both by Western analysis and by immunocytochemistry. Immunoblots revealed the presence of a protein immunoreacting with the anti-bcl-2 polyclonal antibody in leaves of tobacco plants. Furthermore, immunocytochemical localization has shown that this protein is mainly associated with mitochondria, plastids, and nuclei of plant cells. Taken together, our results suggest that bcl-2 is a protein highly conserved throughout evolution.

Red-Emitting Semiconductor Quantum Dot Lasers

Visible-stimulated emission in a semiconductor quantum dot (QD) laser structure has been demonstrated. Red-emitting, self-assembled QDs of highly strained InAlAs have been grown by molecular beam epitaxy on a GaAs substrate. Carriers injected electrically from the doped regions of a separate confinement heterostructure thermalized efficiently into the zero-dimensional QD states, and stimulated emission at approximately 707 nanometers was observed at 77 kelvin with a threshold current of 175 milliamperes for a 60-micrometer by 400-micrometer broad area laser. An external efficiency of approximately 8.5 percent at low temperature and a peak power greater than 200 milliwatts demonstrate the good size distribution and high gain in these high-quality QDs.

The arginine operon of Bacillus stearothermophilus: characterization of the control region and its interaction with the heterologous B. subtilis arginine repressor

Mechanisms of gene regulation have not yet been extensively studied in thermophilic bacteria. In previous studies we showed that the Bacillus stearothermophilus argCJBD gene cluster is subject to specific repression by arginine. Here we report the cloning by colony hybridization, and characterization of the proximal part of the argC gene together with the adjacent control region of the cluster. The promoter was identified by primer extension mapping of the argC transcription startpoint: a sequence overlapping it was found to be similar to the arginine operators of B. subtilis and to a smaller extent of E. coli. Use of an argC-lacZ gene fusion revealed that the argC promoter is strongly repressed by the heterologous B. subtilis arginine repressor/activator AhrC in E. coli cells. Mobility shift and DNase I footprinting experiments revealed tight, specific and arginine-dependent binding of this operator-like sequence to purified AhrC. It is therefore very likely that in B. stearothermophilus the expression of the argCJBD operon is modulated by a repressor that is the thermophilic homologue of AhrC.

A new oxygen-regulated operon in Escherichia coli comprises the genes for a putative third cytochrome oxidase and for pH 2.5 acid phosphatase (appA)

The Escherichia coli acid phosphatase gene appA is expressed in response to oxygen deprivation and is positively controlled by the product of appR (katF) which encodes a putative new sigma transcription-initiation factor. However, transcription of appA from its nearest promoter (P1) did not account for total pH 2.5 acid phosphatase expression and was not subject to regulation. The cloned region upstream of appA was extended and analyzed by insertions of transposon TnphoA and by fusions with lacZ. It contains two new genes, appC and appB, which both encode extracytoplasmic proteins. appC and appB are expressed from a promoter (P2) lying just upstream of appC. Both genes are regulated by oxygen, as is appA, and by appR gene product exactly as previously shown for appA. Analysis of the nucleotide sequence and of the origins of transcription have confirmed that the P2-appC-appB- (ORFX)-P1-appA region is organized on the chromosome as an operon transcribed clockwise from P2 and that P1 is a minor promoter for appA alone. Genes appC and appB encode proteins of Mr 58,133 and 42,377, respectively, which have the characteristics of integral membrane proteins. The deduced amino acid sequences of appC and appB show 60% and 57% homology, respectively, with subunits I and II of the E. coli cytochrome d oxidase (encoded by genes cydA and cydB). The notion that the AppC and AppB proteins constitute a new cytochrome oxidase or a new oxygen-detoxifying system is supported by the observation of enhanced sensitivity to oxygen of mutants lacking all three genes, cyo (cytochrome o oxidase), cyd (cytochrome d oxidase) and appB, compared to that of cyo cyd double mutants.

Repression of the murine interferon alpha 11 gene: identification of negatively acting sequences

The uninducible murine interferon alpha 11 gene (Mu IFN-alpha 11) shows strong homology with the highly inducible Mu IFN-alpha 4 gene in the promoter region. Negative regulatory sequences located between positions -470 and -145 were characterized in the Mu IFN-alpha 11 promoter. The removal of these sequences leads to virus-inducibility of Mu IFN-alpha 11 while their insertion in Mu IFN-alpha 4 corresponding region significantly reduced the inducibility of Mu IFN-alpha 4 promoter. On the other hand, the virus-responsive element (VRE) of the Mu IFN-alpha 11 differs by a single nucleotide substitution at position -78 from the VRE alpha 4. Constructions carrying either VRE alpha 11 or VRE alpha 4 upstream a heterologous promoter displayed different virus inducibilities. The -78 A/G substitution affects the inducibility by decreasing the affinity of VRE-binding trans-regulators. Our results suggest that the combined effect of the negative regulatory sequences and of the mutation in the VRE alpha 11, completely silences the Mu IFN-alpha 11 gene.

Inactivating and mutagenic effects of nitrosoguanide on human cytomegalovirus

Human cytomegalovirus (HCMV) was exposed for 24 hr to 10-30 micrograms/ml nitrosoguanidine (NG) at different times postinfection. NG treatments performed 24 to 48 hr after infection of human IAFP-1 fibroblasts with HCMV interfered most significantly with the replication of the virus. No correlation was found, however, between the inactivating effect of NG at this particular stage of the replication cycle and the induction of HCMV temperature-sensitive mutants. All the 17 HCMV mutant strains isolated on this occasion showed the same BamHI, Cfo I, Hpa II and Sph I restriction profiles which is indicative of mutations caused by single base changes.

[Physical mapping of strain AD169 human cytomegalovirus DNA]

The whole human cytomegalovirus strain AD169 genome was cloned into plasmid pAT153 in the form of 25 HindIII fragments. Double and triple digestions of the recombinant plasmids with restriction endonucleases BamHI, BglII, ClaI, DraI, EcoRI, EcoRV, HindIII, HpaI, KpnI, PaeR7, PstI, SphI and XbaI yielded a detailed restriction map of human cytomegalovirus DNA. Knowing the exact position of numerous restriction sites in the viral DNA molecule, we have been able to examine very closely the heterologous region between the long and the short segments of the human cytomegalovirus genome.

Physical mapping of a temperature-sensitive mutation of human cytomegalovirus by marker rescue

Physical mapping of a temperature-sensitive (ts) mutation of human cytomegalovirus (HCMV) strain AD-169 was attempted here using cloned HindIII restriction endonuclease fragments and the mutant virus. The DNA-positive mutant tested (HCMV ts 1585) was successfully rescued by viral DNA sequences between 0.277 and 0.303 map units. The product of this gene is apparently a structural protein of molecular weight 40,000. Marker rescue could thus be used to establish the physical location of essential HCMV genes, even if the viral DNA molecule is extremely large and complex.

Isolation and characterization of a functional murine interferon alpha gene which is not expressed in fibroblasts upon virus induction

A mouse genomic segment containing three new members of the murine interferon alpha (MuIFN-alpha) gene family was isolated from a fibroblastic cosmid library. A 4 kb EcoRI fragment contained a new MuIFN-alpha gene named MuIFN-alpha 8. The nucleotide sequence of the coding and flanking regions of this gene showed a high level of homology to those of known members of the MuIFN-alpha family. Transient expression of the MuIFN-alpha 8 gene in COS cells and oocyte translation of in vitro transcripts both led to a biologically active protein. The antiviral activity was neutralized by monoclonal and polyclonal MuIFN-alpha antibodies. Although the 5' flanking sequence shows features characteristic of an IFN regulatory region, the MuIFN-alpha 8 gene is not expressed in murine fibroblasts treated with Newcastle disease virus or poly(I).poly(C).

Expression of the MuIFN alpha 7 gene in Bacillus subtilis using the levansucrase system

The mouse interferon alpha 7 gene, the signal sequence of which has been removed by oligonucleotide-directed mutagenesis, was introduced into a Bacillus subtilis secretion vector containing the promoter and the signal sequence of the B. subtilis levansucrase gene. Different B. subtilis strains were transformed with the fused levansucrase-interferon gene; their cell extracts and culture supernatants tested for antiviral activity and the IFN alpha 7 protein showed the presence of IFN alpha 7 only in the cell extracts. To promote IFN alpha 7 secretion, constructs were realized in order to restore the alpha helix conformation of the signal sequence of levansucrase and interferon protein junction. Our results suggest that factors other than the structure of the peptide around the cleavage site are involved in the secretion of IFN alpha 7 by B. subtilis.

Detection of recombination events in human cells using cloned cytomegalovirus DNA fragments as probes

A method is presented for the detection of virus-host interactions at the chromosomal level. This method relies on the analysis of recombinant plasmids carrying specific regions of a viral DNA molecule. Human cytomegalovirus HindIII subgenomic fragments were used here as a target for recombination events.