Medium term survival in patients over ninety years-old undergoing pacemaker implantation

Background

According to the Italian National Statistical Institute, the 12-month probability of survival in the general population between 90 and 94 years-old is 26%. Pacemaker (PM) implantation is often an urgent and necessary intervention, but in these patients the benefit in terms of quality and duration of life is unclear.

Purpose

To analyze characteristics, outcome and factors associated with survival in patients who had turned 90 at the time of PM implant.

Methods

All the PM implants performed in patients ≥90 from 1/1/2019 to 12/31/2020 were analyzed. Clinical parameters, device characteristics and follow-up data were extrapolated from the SuitEstensa Ebit reporting system; the exitus was verified by analyzing data from the Regional Health System.

Results

During the study interval, among the 554 patients undergoing PM implantation in our Center, 69 (12%) were ≥90 years-old (mean age 92±2 years, 46% male; complete/advanced AV block in 76%). Twenty-six (38%) patients had history of atrial fibrillation and 19 (28%) ischemic heart disease. A cardiological co-morbidity (excluding AF) was present in 23 patients (33%). Oncological, pneumological and neurological comorbidities were present in 12 (18%), 19 (28%) and 32 (46%) respectively. Renal impairment was present in 25 patients (36%). In 47 patients (68%) there were at least 2 co-morbidities. After implantation (single-chamber in 36, dual-chamber in 25 and VDD single-lead dual-chamber in 8 patients) complications occurred in 3 patients (2 pneumothorax and 1 lead dislodgment). Remote monitoring was activated in 57 patients (83%).

Within August 31st 2021 (mean follow-up 288±193 days) 24 patients died (35%, 219±241 days after implant). Five patients (19% of patients implanted in 2019) died within 12 months. No patients died for device malfunction. Three patients died because of COVID-19 pneumonia.

Renal dysfunction (Hazard Ratio-HR 8.05, p=0.002) and the presence of 2 or more co-morbidities (HR 6.03; p=0.015) were associated with a higher risk of death at univariate analysis; other significant variables were diabetes (HR 2.34; p=0.038), left ventricular ejection fraction (LVEF) (HR 0.70 for 5% variation; p=0.005), walking impairment (HR 2.99, p=0.006), the presence of oncological (HR 2.21; p=0.003), pneumological (HR 2.55; p=0.024) and neurological (HR 1.90, p=0.007) comorbidities. At multivariable analysis the only significant parameter associated with survival was LVEF (0.76 for 5% difference; p=0.043)

Conclusions

At our Center, patients ≥90 years-old undergo PM implantation mainly for advanced AVB. The good survival in the medium term, even better than expected in the general population, does not justify a too conservative attitude especially, but exclusively, in patients with less comorbidities.

Funding Acknowledgement

Type of funding sources: None.

P295 EXERCISE OXYGEN KINETIC IN HYPERTROPHIC CARDIOMYOPATHY: RESULTS FROM A MULTICENTER CARDIOPULMONARY EXERCISE TESTING STUDY

Aims

Reduced cardiac output (CO) has been considered crucial in symptoms’ genesis in hypertrophic cardiomyopathy (HCM). We evaluated the cardiopulmonary exercise testing (CPET) response in HCM focusing on parameters strongly associated with stroke volume (SV) and cardiac output (CO), such as oxygen uptake (VO2) and O2–pulse, considering both their absolute values and temporal behavior during physical exercise.

Methods and Results

We enrolled 312 non–end stage HCM patients, divided according to left ventricle outflow tract obstruction (LVOTO) at rest or during Valsalva maneuver (72% with LVOTO<30; 10% between 30 and 49 and 18% ≥ 50mmHg). Peak VO2 (percent of predicted), O2–pulse and ventilation to carbon dioxide production (VE/VCO2) slope did not change across LVOTO groups. Ninety–six (31%) HCM patients presented an abnormal O2–pulse temporal behavior, irrespective of LVOTO values. These patients showed lower peak systolic pressure, workload (106±45 vs. 130±49W), VO2 (74±17 vs. 80±20%) and O2–pulse (12 [9–14] vs. 14 [11–17]ml/beat), with higher VE/VCO2 slope (28 [25–31] vs. 27 [24–31]) (p < 0.005 for all). Only 2 patients had an abnormal VO2/work slope.

Conclusion

None of CPET parameters, either as absolute values or dynamic relationships, were associated with LVOTO. Differently, an abnormal O2–pulse exercise behavior, which is strongly related to inadequate SV during exercise, correlates with reduced functional capacity (peak and anaerobic threshold VO2 and workload) and increased VE/VCO2 slope, helping identifying more advanced disease irrespectively of LVOTO. Adding O2–pulse kinetics evaluation to standard CPET could lead to a potential incremental benefit in terms of HCM prognostic stratification and, then, therapeutic management.

Association between common cardiovascular risk factors and clinical phenotype in patients with hypertrophic cardiomyopathy from the European Society of Cardiology (ESC) EurObservational Research Programme (EORP) Cardiomyopathy/Myocarditis registry

AIMS

The interaction between common cardiovascular risk factors (CVRF) and hypertrophic cardiomyopathy (HCM) is poorly studied. We sought to explore the relation between CVRF and the clinical characteristics of patients with HCM enrolled in the EURObservational Research Programme (EORP) Cardiomyopathy registry.

METHODS AND RESULTS

1739 patients with HCM were studied. The relation between hypertension (HT), diabetes (DM), body mass index (BMI), and clinical traits was analysed. Analyses were stratified according to the presence or absence of a pathogenic variant in a sarcomere gene. The prevalence of HT, DM, and obesity (Ob) was 37, 10, and 21%, respectively. HT, DM, and Ob were associated with older age (P<0.001), less family history of HCM (HT and DM P<0.001), higher New York Heart Association (NYHA) class (P<0.001), atrial fibrillation (HT and DM P<0.001; Ob p = 0.03) and LV (left ventricular) diastolic dysfunction (HT and Ob P<0.001; DM P = 0.003). Stroke was more frequent in HT (P<0.001) and mutation-positive patients with DM (P = 0.02). HT and Ob were associated with higher provocable LV outflow tract gradients (HT P<0.001, Ob P = 0.036). LV hypertrophy was more severe in Ob (P = 0.018). HT and Ob were independently associated with NYHA class (OR 1.419, P = 0.017 and OR 1.584, P = 0.004, respectively). Other associations, including a higher proportion of females in HT and of systolic dysfunction in HT and Ob, were observed only in mutation-positive patients.

CONCLUSION

Common CVRF are associated with a more severe HCM phenotype, suggesting a proactive management of CVRF should be promoted. An interaction between genotype and CVRF was observed for some traits.

A multiparametric ICD algorithm for heart failure risk stratification and management: an analysis in clinical practice

Funding Acknowledgements

Type of funding sources: None.

Introduction

The HeartLogic algorithm combines multiple implantable cardioverter defibrillator (ICD) sensors to identify patients at risk of heart failure (HF) events.

Purpose

We sought to evaluate the risk stratification ability of this algorithm in clinical practice. We also analyzed the alert management strategies adopted in the study group and their association with the occurrence of HF events.

Methods

The HeartLogic feature was activated in 366 ICD and cardiac resynchronization therapy ICD patients at 22 centers. The HeartLogic algorithm automatically calculates a daily HF index and identifies periods IN or OUT of an alert state on the basis of a configurable threshold (in this analysis set to 16).

Results

The HeartLogic index crossed the threshold value 273 times (0.76 alerts/patient-year) in 150 patients over a median follow-up of 11 months [25-75 percentile: 6-16]. Overall, the time IN the alert state was 11% of the total observation period. Patients experienced 36 HF hospitalizations and 8 patients died of HF (rate: 0.12 events/patient-year) during the observation period. Thirty-five events were associated with the IN alert state (0.92 events/patient-year versus 0.03 events/patient-year in the OUT of alert state). The hazard ratio in the IN/OUT of alert state comparison was (HR: 24.53, 95% CI: 8.55-70.38, p &lt; 0.001), after adjustment for baseline clinical confounders. Alerts followed by clinical actions were associated with a lower rate of HF events (HR: 0.37, 95% CI: 0.14-0.99, p = 0.047). No differences in event rates were observed between in-office and remote alert management. By contrast, verification of HF symptoms during post-alert examination was associated with a higher risk of HF events (HR: 5.23, 95% CI: 1.98-13.83, p &lt; 0.001).

Conclusions

This multiparametric ICD algorithm identifies patients during periods of significantly increased risk of HF events. The rate of HF events seemed lower when clinical actions were undertaken in response to alerts. Extra in-office visits did not seem to be required in order to effectively manage HeartLogic alerts, while post-alert verification of symptoms seemed useful in order to better stratify patients at risk of HF events.

Implantable cardioverter defibrillator multisensor monitoring during home confinement caused by the covid-19 pandemic

Funding Acknowledgements

Type of funding sources: None.

Background

Utilization of remote monitoring platforms was recommended amidst the COVID-19 pandemic. The HeartLogic algorithm combines data from multiple implantable cardioverter defibrillator (ICD) sensors (first and third heart sounds, intrathoracic impedance, respirations, night heart rate, and patient activity) to provide integrated data that may allow for detection of early signs of worsening HF.

Purpose

We examined whether the HeartLogic platform may elucidate behavioral changes that impact HF decompensation, and the possible consequences of home confinement caused by the COVID-19 pandemic.

Methods

The Italian lockdown was imposed from March 8th to May 18th. On March 8th 2020, the HeartLogic feature was active in 349 ICD and cardiac resynchronization therapy ICD patients at 20 Italian centers. The period from January 1st to July 19th was divided in 3 phases: Pre-Lockdown (weeks 1-11), Lockdown (weeks 12-20), Post-Lockdown (weeks 21-29).

Results

Immediately after the implementation of stay at home orders (week 12) we observed a significant drop in median activity level (65min [36-103] in week 12 vs. 101min [61-140] in Pre-Lockdown; p < 0.001), while there was no difference in the other contributing sensors. The median composite HeartLogic index increased at the end of Lockdown (4.7 [1.3-10.2] in week 20 vs. 2.5 [0.7-7.0] in Pre-Lockdown; p = 0.019). The weekly rate of HeartLogic alerts was significantly higher during Lockdown (1.56 alerts/week/100pts, 95%CI:1.15-2.06; IRR = 1.71, p = 0.014) and Post-Lockdown (1.37 alerts/week/100pts, 95%CI:0.99-1.84; IRR = 1.50, p = 0.072) than that reported in Pre-Lockdown (0.91 alerts/week/100pts, 95%CI:0.64-1.27). However, the median duration of alert state and the maximum index value did not change among phases, as well as the proportion of alerts followed by clinical actions at the centers (Pre-Lockdown: 31%, Lockdown: 22%, Post-Lockdown: 28%), and the proportion of alerts fully managed remotely (i.e. no in-clinic visits) (Pre-Lockdown: 89%, Lockdown: 90%, Post-Lockdown: 88%).

Conclusions

The system was sensitive to the behavioral changes occurred during the lockdown, i.e. decrease in activity. However, the home confinement had no impact on the other sensors. The higher rate of HeartLogic alerts during lockdown and the increase in the median index after 8 weeks of home confinement suggest the worsening of the HF status, possibly explained by the behavioral changes. Nonetheless, the management of the HF detected events (actions performed and management strategy) was not impacted by the restrictions.

Multidisciplinary care management has a positive effect on paediatric obesity and social and individual factors are associated with better outcomes

AIM

The RePPOP Aquitaine network, which was established in south-west France to prevent and treat paediatric obesity, has developed a multidisciplinary approach based on multicomponent lifestyle interventions and family-based actions. This study assessed the impact of its care management programme and investigated the factors associated with better outcomes.

METHODS

The impact of the RePPOP care management programme was assessed by changes in the body mass index (BMI) Z score, between baseline and the end-of-care management. We focused on 982 overweight or obese children (59.9% girls) with a mean age of 10.64 years and a range of 2.4-17.9 years. A multivariate analysis examined the independent factors associated with better outcomes.

RESULTS

At the end-of-care management programme, 75.5% of children had decreased their BMI Z score. Initial characteristics significantly associated with better outcomes were as follows: the age at baseline between five years and 15 years of age, playing sport at a club, being followed up by RePPOP for longer than 10 months, no parental obesity and no academic difficulties.

CONCLUSION

This study confirmed that multidisciplinary treatment had a significant positive effect on paediatric obesity and that social and individual factors affected the efficiency of the care management.

[Morning snack offer in kindergarten: outlook and practices in Aquitaine, France, between 2004 and 2008]

The Nutrition, Prevention and Health for Children and Teenagers in Aquitaine program is a regional implementation of the French National Program of Nutrition and Health (PNNS). The first of two surveys of a representative sample of Aquitaine preschools was conducted in 2004-2005. This survey showed that more than 2/3 of teachers offered a morning snack to their pupils at around 10 o'clock in the morning, mainly composed of sweet cakes, cookies, or candies. Following this initial survey, actions were implemented starting in September 2005, aiming to stop systematic morning snacks or improve their composition. The same survey was repeated during 2007-2008 in order to analyze the changes in morning snack practices in preschools between 2004-2005 and 2007-2008. Data were collected from teachers of Aquitaine's preschools who filled out questionnaires. Schools were randomly chosen according to their size and whether or not they belonged to a priority education zone (ZEP). The results show that 57.9% of teachers organized a morning snack in 2007-2008, versus 68.7% in 2004-2005. In 2004-2005, 22% of teachers considered the morning snack as "unjustified" compared to 44% in 2007-2008. The composition of morning snacks improved: 17.7% of teachers offered fruit and/or milk in 2007-2008 versus 8.5% in 2004-2005. Morning snacks composed of other foods (such as sweets, chocolate pieces, cookies, pastries, bread, fruit juice) decreased from 60.2% in 2004-2005 to 40.2% in 2007-2008. In 2007-2008, 19% of the teachers reported that children had snacks in their schoolbag versus 34% in 2004-2005. The proportion of teachers reporting children having snacks in their schoolbag decreased from 34% in 2004-2005 to 19% in 2007-2008. Comparison between these two surveys is encouraging as it shows an improvement of the perception and practices of teachers regarding morning snacks. These results encourage the partners of this program to continue the fieldwork actions.

[Early screening criteria for children at risk of overweight]

BACKGROUND

Health professionals who monitor the growth of children are also involved in the early detection of overweight. Appropriate tools are required for this purpose.

OBJECTIVE

The study sought to identify predictive markers of the development of subsequent overweight using a simple set of criteria.

METHODS

A consecutive cohort was composed of 1424 grade 4 children in Aquitaine, France, aged 8-9 years. Body mass index (BMI) was calculated during school health assessments at 8-9 years of age. Data from previous assessments at 3-4 and 5-6 years of age were also collected.

RESULTS

Of the 189/1424 children (13.9 %) who were overweight according to the French national cut off for children aged 8-9 years, 67 (33.8 %) were already overweight at 3-4 years and 107 (54.1 %) at 5-6 years. Of the 134 (9.4 %) who were overweight at 5-6 years, 43.3 % were already overweight at 3-4 years and 79.9 % were overweight at 8-9 years. On the other hand, 76 of these 134 children (56.7 %) were not overweight at 3-4 years, so they had become overweight between the two assessments. The combination of the criterion "overweight at 3-4 years or 5-6 years" and "increase in BMI>1kg/m(2) between 3-4 years and 5-6 years" appears to be the best predictor of the risk of overweight at 8-9 years, with good sensitivity (75.3 %) and specificity (87.9 %).

CONCLUSION

A predictive tool based on BMI changes between ages 3-4 years and 5-6 years could be used for the early detection of the risk of developing overweight and obesity. The tool is easy to use, especially for health care in schools. Furthermore, the present findings confirm the value of following up and managing children who are already overweight between the ages of 3 and 6 years.

First molecular epidemiology study of Mycobacterium tuberculosis in Burkina Faso

We conducted a molecular epidemiology study on 120 Mycobacterium tuberculosis isolates from patients presenting pulmonary tuberculosis (TB) in Burkina Faso. Classical antibiogram studies and genetic characterization, using mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) typing and spoligotyping, were applied after culture. Molecular analysis of specific signatures showed that all TB cases reported in this study were caused by M. tuberculosis and identified no Mycobacterium bovis or Mycobacterium africanum isolates. This result is unexpected, as M. africanum strains were reportedly the etiologic agent in 20% of TB cases 2 decades ago. The comparison of spoligotypes from Burkina Faso with an international spoligotype database (SpolDB4) showed that the majority of isolates belong to major clades of M. tuberculosis (Haarlem, 9%; Latin American-Mediterranean, 30%; and T, 20%). The predominant group of isolates (30%) corresponds to spoligotype 61, described in Cameroon as the "Cameroon family." In Burkina Faso, as in Cameroon, this family could be associated with recent transmission of TB, suggesting a recent expansion in West Africa. Our data suggest a low level of primary drug resistance that may be a positive result of the Directly Observed Therapy Shortcourse program. Besides, based on spoligotyping plus MIRU-VNTR, data showed a high number of clusters in our sample, suggesting a high level of recent TB transmission in Burkina Faso. Nevertheless, an important genetic polymorphism was observed in this country, reflecting an endemicity situation where the control of TB would have less impact in the main towns.

Implantable insulin pumps: infections most likely due to seeding from skin flora determine severe outcomes of pump-pocket seromas

Complications at implantation site of implantable insulin pumps may lead to premature removal. To elucidate the origins and the outcomes of these local adverse events. We investigated seromas of the 'pump-pocket' that have been detected for an eight month-period during the follow-up of such-treated forty type 1 diabetic patients. At the start of study period, skin bacterial flora was sampled at umbilicus and groin, and isolated strains of Staphylococcus epidermidis were preserved in specific vials at -20 degrees C. Each time a seroma was detected at transcutaneous 45 days-refill of pump reservoir, it was sampled for bacterial cultures. Isolated strains of S. epidermidis from seroma were genetically compared to preserved strains of corresponding patients using Pulsed-Field Gel Electrophoresis (PFGE) after genomic restriction by SmaI. Among the ten seromas that occurred after a mean time of 9.9 months since implantation, S. epidermidis were isolated in five cases. Genetic comparison of isolated strains could be performed in three cases. Compared strains showed identical (in 2 cases) or closely related (in one case) PFGE profiles. While the five aseptic seromas resolved with rest, four infected cases required explantations after one to nineteen months in spite of antibiotic therapy and the fifth one persisted without impairment under long-term antibiotics. Our results suggest that seeding from the skin flora is a key-factor determining the severity of pump-pocket complications. We recommend that bacterial investigations of pump-pocket seromas should be systematically performed, while prophylactic measures might include antibiotic cover for each puncture of the pump-pocket.

Production of a TEM-24 plasmid-mediated extended-spectrum beta-lactamase by a clinical isolate of Pseudomonas aeruginosa

Several Pseudomonas aeruginosa strains, including one urinary isolate producing an extended-spectrum beta-lactamase TEM-24, were isolated from a long-term-hospitalized woman. Three TEM-24-producing enterobacterial species (Enterobacter aerogenes, Escherichia coli, and Proteus mirabilis) were isolated from the same patient. TEM-24 and the resistance markers for aminoglycosides, chloramphenicol, and sulfonamide were encoded by a 180-kb plasmid transferred by conjugation into E. coli HB101.

Fine needle aspiration (FNA) biopsy of palpable breast masses: comparison of conventional smears with the Cyto-Tek MonoPrep system

BACKGROUND

One of the limitations preventing the widespread use of fine-needle aspiration (FNA) is that it requires skill to obtain an adequate sample and well prepared smears. In this study, a new monolayer technique, the Cyto-Tek MonoPrep (MP) system, which obviates the need for smear preparation, was evaluated against conventional smear (CS) preparation for palpable breast lesions.

METHODS

A total of 44 paired CS/MP breast FNA specimens were studied. The authors blindly analyzed the CS and the MP slides separately, then by a side-by-side evaluation. The two methods were compared with respect to diagnostic concordance, cellularity, cell preservation, background debris, and time needed to prepare and diagnose each case.

RESULTS

An exact diagnostic correlation was present in 34 of 44 (77%) cases. The 10 noncorrelating cases were caused by decreased cellularity in the MP cases; nonetheless, 7 of these were correctly assigned to the right general diagnostic category, whereas the remaining 3 cases had insufficient cells. In addition to overall lesser cellularity on MP, fibroadenoma cases had smaller epithelial sheets and absence of stroma compared with CS. Both methods had comparable cellular preservation and diagnostic evaluation time, but background debris and preparation time were greater for MP.

CONCLUSION

CS are favored over MP for the preparation of breast FNA specimens in centers with specialized FNA services because of their higher diagnostic yield, ease of preparation, and availability for immediate cytologic evaluation. However, in settings where specimens are collected sporadically by unskilled clinicians, the MP system may prove to be useful as an alternative or an adjunct to CS. Cancer (Cancer Cytopathol)

TEM-24 produced by four different species of Enterobacteriaceae, including Providencia rettgeri, in a single patient

Four species of members of the family Enterobacteriaceae harboring extended-spectrum beta-lactamase (ESBL) were recovered in a single patient hospitalized in an intensive care unit. Among these isolates, we describe for the first time an ESBL-producing Providencia rettgeri strain. Bacteria from the same species were shown to be genetically related by pulsed-field gel electrophoresis analysis. These strains produced the same TEM derivative ESBL, characterized as TEM-24. This enzyme had the peculiarity of being encoded by a large conjugative plasmid of 180 kb, never previously described for such an ESBL.

Nocardia thyroiditis: unusual location of infection

Nocardia asteroides complex is an important opportunistic agent in immunocompromised hosts. Usually, primary pulmonary infection occurs and is followed by dissemination of the pathogen to the central nervous system and soft tissues. As described in the literature, almost every organ can be infected, but to our knowledge, Nocardia has been described as a pathogen responsible for thyroid abscess in only one report, which was published in 1993. The present report is the second case report of Nocardia thyroiditis. The patient was under immunosuppressor treatment following a combined liver-kidney transplant and presented with a preexisting nodular goiter which was probably a predisposing factor to the start and development of the thyroid infection.

Local anesthesia for fine-needle aspiration biopsy of palpable breast masses: the effectiveness of a jet injection system

To determine the effectiveness of the Biojector 2000 needle-free lidocaine injection system in achieving satisfactory local anesthesia for fine-needle aspiration (FNA) of palpable breast lesions, we studied 29 female patients. Each patient served as her own control and had two FNA biopsies performed on the lesion. The first FNA biopsy was preceded by either no anesthesia, ethyl chloride cold spray, or traditional needle lidocaine injection. The second FNA was preceded by the Biojector 2000. Twenty-four patients (83%) reported that they preferred the Biojector 2000 over either no anesthesia, ethyl chloride spray, or needle and syringe lidocaine injection. The Biojector 2000 needle-free injection system is an effective and useful method of local anesthesia for FNA of palpable breast masses.

Mucor pyelonephritis. Report of a case diagnosed by urine cytology, with diagnostic considerations in the workup of funguria

BACKGROUND

Isolated renal mucormycosis is an uncommon kidney infection affecting patients with underlying systemic diseases and intravenous (IV) drug abuse. We report a unique case in the cytologic literature in which urine cytology provided insight into the diagnosis, renal mucormycosis.

CASE

The patient, a diabetic and IV drug abuser, presented with complaints of left flank pain, fever and dysuria. All urine cultures were negative. A computed tomography (CT) scan showed changes consistent with left acute pyelonephritis, and the patient was treated for a presumed diagnosis of bacterial pyelonephritis. Late in the hospital stay, the cytology laboratory diagnosed Mucor in a single urine specimen, but the patient had already been discharged. The patient was never treated for funguria, only to present again with left flank pain 13 months later. An abdominopelvic CT scan showed progression to left chronic pyelonephritis. The patient, however, left the hospital against medical advice before any further workup could be completed.

CONCLUSION

Renal mucormycosis should be considered part of the differential diagnosis in patients with underlying diseases or IV drug abuse who present with symptoms of acute pyelonephritis. The differential diagnosis of Mucor funguria should also include fungal ball in the renal pelvis or urinary bladder and fungal cystitis.

Conditionally replicating mycobacteriophages: a system for transposon delivery to Mycobacterium tuberculosis

Transposon mutagenesis provides a direct selection for mutants and is an extremely powerful technique to analyze genetic functions in a variety of prokaryotes. Transposon mutagenesis of Mycobacterium tuberculosis has been limited in part because of the inefficiency of the delivery systems. This report describes the development of conditionally replicating shuttle phasmids from the mycobacteriophages D29 and TM4 that enable efficient delivery of transposons into both fast- and slow-growing mycobacteria. These shuttle phasmids consist of an Escherichia coli cosmid vector containing either a mini-Tn10(kan) or Tn5367 inserted into a nonessential region of the phage genome. Thermosensitive mutations were created in the mycobacteriophage genome that allow replication at 30 degrees C but not at 37 degrees C (TM4) or 38.5 degrees C (D29). Infection of mycobacteria at the nonpermissive temperature results in highly efficient transposon delivery to the entire population of mycobacterial cells. Transposition of mini-Tn10(kan) occurred in a site-specific fashion in M. smegmatis whereas Tn5367 transposed apparently randomly in M. phlei, Bacille Calmette-Guérin (BCG), and M. tuberculosis. Sequence analysis of the M. tuberculosis and BCG chromosomal regions adjacent to Tn5367 insertions, in combination with M. tuberculosis genomic sequence and physical map data, indicates that the transpositions have occurred randomly in diverse genes in every quadrant of the genome. Using this system, it has been readily possible to generate libraries containing thousands of independent mutants of M. phlei, BCG, and M. tuberculosis.

Comparison of packaging strategy in retroviruses and pararetroviruses

Reverse transcription is not solely a retroviral mechanism. Animal hepadnaviruses, plant caulimoviruses, and badnaviruses have a RNA intermediate which is reverse transcribed into double-stranded DNA genome. Based on this fact, these three groups of viruses have been regrouped under the name of pararetroviruses. Although each one has developed its own strategy to assure an efficient packaging of their genome, it is clear that they have adopted a strategy where encapsidation prepares for initiation of reverse transcription. This is discussed in this review.

Pax-QNR/Pax-6, a paired box- and homeobox-containing gene expressed in neurons, is also expressed in pancreatic endocrine cells

After differential screening of a cDNA library constructed from quail neuroretina cells infected with the v-myc containing avian retrovirus MC29, we have isolated a cDNA clone Pax-QNR, homologous to the murine Pax6 which is mutated in the autosomal dominant mutation small eye (Sey) of the mouse and aniridia in man. Here we report the characterization of Pax-QNR/Pax-6 expression in the chicken, quail, and mouse pancreas. In situ hybridization performed with E3 chick embryos demonstrated that, in addition to the documented expression of Pax-QNR/Pax-6 in the neural tube, this gene is also expressed in the pancreatic bud. This expression is later restricted to discrete parts of the organ. From bacterially expressed Pax-QNR peptides we obtained rabbit antisera (paired domain, serum 11; domain between paired and homeo, serum 12; homeodomain, serum 13; and carboxyl-terminal part, serum 14) capable of specifically recognizing Pax-QNR/Pax-6 proteins (48, 46 kilodaltons) in cell lines derived from alpha- and beta-pancreatic cells, but not from exocrine derived cell lines. We conclude that Pax-QNR/Pax-6 represents another gene expressed both in the endocrine pancreas and neuro-ectodermic tissues.

Characterization of quail Pax-6 (Pax-QNR) proteins expressed in the neuroretina

After differential screening of a cDNA library constructed from quail neuroretina cells (QNR) infected with the v-myc-containing avian retrovirus MC29, we have isolated a cDNA clone, Pax-QNR, homologous to the murine Pax-6, which is mutated in the autosomal dominant mutation small eye of mice and in the disorder aniridia in humans. Here we report the characterization of the Pax-QNR proteins expressed in the avian neuroretina. From bacterially expressed Pax-QNR peptides, we obtained rabbit antisera directed against different domains of the protein: paired domain (serum 11), domain between the paired domain and homeodomain (serum 12), homeodomain (serum 13), and carboxyl-terminal part (serum 14). Sera 12, 13, and 14 were able to specifically recognize five proteins (48, 46, 43, 33, and 32 kDa) in the neuroretina. In contrast to proteins of 48, 46, and 43 kDa, proteins of 33 and 32 kDa were not recognized by the paired antiserum (serum 11). Paired-less and paired-containing proteins exhibited the same half-life (6 h) and were phosphorylated mostly on serine residues. Immunoprecipitations performed with subcellular fractions of neuroretinas showed that the paired-containing proteins were located in the nucleus, whereas the 33- and 32-kDa proteins were found essentially in the cytoplasmic compartment. However, immunofluorescence experiments performed after transient transfections showed that p46 and p33/32 were also located in vivo into the nucleus. Thus, the Pax-QNR/Pax-6 gene can produce proteins with two DNA-binding domains as well as proteins containing only the DNA-binding homeodomain.

Characterization of a paired box- and homeobox-containing quail gene (Pax-QNR) expressed in the neuroretina

The retina is an integral part of the central nervous system, and consists of two layers, the outer pigmented layer and the inner sensory layer or neuroretina (NR). The NR layer contains several strata of cells (glial and neuronal) derived from proliferating neuroectodermal precursors that differentiate after terminal mitosis. In vitro, NR cells can differentiate not only into neuronal and glial types, but also into pigment and lens cells. Quail (Coturnix coturnix japonica) NR cells (QNR) infected with MC29 transforming retrovirus become pigmented after several passages in vitro. In order to characterize the genes expressed in these pigmented MC29 QNR, a cDNA library was prepared from these cells. After differential screening we have isolated a cDNA clone which identifies an RNA expressed in NR but not in the pigmented layer of the retina. This cDNA encodes a protein related to that of Drosophila, mouse and zebrafish paired box- and homeobox-containing segmentation genes and is called Pax-QNR. The expression of Pax-QNR in the NR is confined to the ganglionic cell layer and to the lower part of the inner nuclear layer containing the amacrine or correlation neurones.

DNA polymorphism in strains of Listeria monocytogenes

DNA polymorphism in 35 Listeria monocytogenes strains belonging to serovars 1/2a, 1/2b, 1/2c, and 4b was studied by genomic DNA digestion. The restriction endonucleases ApaI and NotI, which cleave DNA at rare sequences, were used, and DNA fragments were analyzed by pulsed-field gel electrophoresis. Restriction fragment length polymorphism varied among different serovars and was used for epidemiological studies, but serovar 1/2c isolates could not be analyzed because their restriction patterns were indistinguishable. The genome sizes were calculated by addition of the sizes of the ApaI fragments and were found to be about 2,660 kb for serovar 1/2a strains, 2,640 kb for serovar 1/2b strains, and 2,710 kb for serovar 4b strains but only 2,340 kb for serovar 1/2c strains. This last group therefore appears to differ from the other serovar strains by the absence of restriction fragment length polymorphism and a chromosome that is 15% shorter, suggesting that strains of serovar 1/2c have quite recently emerged.