Correlación de la captación de 18F-FDG de la PET/TC con el Ki67 de la inmunohistoquímica en el cáncer epitelial de ovario pretratamiento / Correlation of 18F-FDG uptake on PET/CT with Ki67 immunohistochemistry in pre-treatment epithelial ovarian cancer

Objetivo. El Standardized uptake value (SUV) y los parámetros volumétricos volumen metabólico tumoral (MTV) y glicolisis total de la lesión (TLG) de la 18F-FDG PET/TC son útiles para determinar el pronóstico preoperatorio y postratamiento del cáncer epitelial de ovario (CEO). El Ki67 es otro marcador pronóstico en el CEO asociado con la agresividad tumoral. El objetivo fue estudiar la asociación entre los parámetros de la 18F-FDG PET/TC y el Ki67 en el CEO pretratamiento para determinar si la PET/TC puede predecir la agresividad tumoral de forma no invasiva. Material y métodos. Se realizó una PET/TC a 18 pacientes con sospecha o recién diagnóstico de CEO. Se obtuvo el SUV máximo (SUVmax), SUV medio (SUVmean) y el MTV y la TLG corporal (wbMTV y wbTLG, respectivamente), con un dintel del 30%-40% del SUVmax. Se estimó el índice de Ki67 (medio y máximo) en muestras del tejido tumoral, y se correlacionó con los parámetros de la PET. Resultados. La edad media fue 57,0 años (desviación estándar 13,6 años). Se observó una moderada correlación entre el Ki67 medio y el SUVmax (r=0.392), SUVmean 30% (r=0.437) y SUVmean 40% (r=0.443), así como entre el Ki67 máximo y el SUVmax (r=0.360), SUVmean 30% (r=0.362) y SUVmean 40% (r=0.319). La correlación fue más débil, e inversamente negativa, entre el Ki67 medio y máximo y los parámetros volumétricos de la PET. No hubo diferencias estadísticamente significativas entre las correlaciones. Conclusiones. SUVmax y SUVmean se correlacionaron moderadamente con el Ki67 mientras que los parámetros volumétricos mostraron una correlación débil. SUVmax y SUVmean podrían utilizarse para predecir la agresividad tumoral en el CEO pretratamiento (AU)

Objective. Standardised uptake value (SUV) and volumetric parameters such as metabolic tumour volume (MTV) and total lesion glycolysis (TLG) from 18F-FDG PET/CT are useful criteria for disease prognosis in pre-operative and post-treatment epithelial ovarian cancer (EOC). Ki67 is another prognostic biomarker in EOC, associated with tumour aggressiveness. The aim of this study is to evaluate the association between 18F-FDG PET/CT measurements and Ki67 in pre-treatment EOC to determine if PET/CT parameters could non-invasively predict tumour aggressiveness. Material and methods. A pre-treatment PET/CT was performed on 18 patients with suspected or newly diagnosed EOC. Maximum SUV (SUVmax), mean SUV (SUVmean), whole-body MTV (wbMTV), and whole-body TLG (wbTLG) with a threshold of 30% and 40% of the SUVmax were obtained. Furthermore, Ki67 index (mean and hotspot) was estimated in tumour tissue specimens. Immunohistochemical findings were correlated with PET parameters. Results. The mean age was 57.0 years old (standard deviation 13.6 years). A moderate correlation was observed between mean Ki67 index and SUVmax (r=0.392), SUVmean 30% (r=0.437), and SUVmean 40% (r=0.443), and also between hotspot Ki67 index and SUVmax (r=0.360), SUVmean 30% (r=0.362) and SUVmean 40% (r=0.319). There was a weaker correlation, which was inversely negative, between mean and hotspot Ki67 and volumetric PET parameters. However, no statistical significant differences were found for any correlations. Conclusions. SUVmax and SUVmean were moderately correlated with Ki67 index, whereas volumetric PET parameters overall, showed a weaker correlation. Thus, SUVmax and SUVmean could be used to assess tumour aggressiveness in pre-treatment EOC (AU)

Abordaje multimodal en la cirugía radioguiada de un caso de paraganglioma múltiple / Multimodal approach in radioguided surgery in a case of multiple paraganglioma

Mujer de 34 años intervenida quirúrgicamente de un paraganglioma retroperitoneal adyacente al polo inferior del riñón izquierdo, visualizado por TC y RM. La gammagrafía con 123I-MIBG fue positiva y además se evidenció otra captación de menor intensidad, prevertebral-L5, no subsidiaria de extirpación debido a la ausencia de traducción radiológica. Una semana después de la cirugía, la paciente presentó HTA de difícil control. Se realizó un segundo estudio con 123I-MIBG. La imagen sin traducción radiológica previa mostró mayor captación gammagráfica y fue localizada en las imágenes morfológicas, por lo que se reintervino la paciente. Se utilizó una combinación de técnicas, incluyendo freehand-SPECT y una gammacámara portátil-híbrida (con cámara óptica) para identificar la localización de la lesión, consiguiendo una buena planificación preoperatoria. La combinación de sonda gamma laparoscópica y gammacámara portátil-híbrida permitió la localización intraoperatoria del tumor y la evaluación de su completa extirpación. El análisis anatomopatológico confirmó un segundo paraganglioma (AU)

The case involves a 34-year-old woman who underwent surgical removal of a retroperitoneal paraganglioma adjacent to the left kidney's lower pole, previously visualized by CT and MRI. The 123I-MIBG scan was positive for this lesion and, in addition, another uptake was observed located caudally at the level of L5 and of smaller size and less intensity. The second lesion was not considered for surgical removal, due to its lack of morphological definition. One week after surgical intervention, the patient presented difficult-to-control high blood pressure. A second 123I-MIBG scan was performed. The previously described second image was more intense in this study, and surgery was planned to remove it. A combination of techniques including freehand-SPECT and a portable hybrid gamma camera (with optical camera) were used pre-operatively to identify the location of the lesion. The combination of intra-operative laparoscopic gamma probe and portable hybrid gamma camera enabled the tumor to be located, excised, and its complete removal to be monitored. The histopathology analysis confirmed a second paraganglioma (AU)

Multimodal approach in radioguided surgery in a case of multiple paraganglioma. / Abordaje multimodal en la cirugía radioguiada de un caso de paraganglioma múltiple.

The case involves a 34-year-old woman who underwent surgical removal of a retroperitoneal paraganglioma adjacent to the left kidney's lower pole, previously visualized by CT and MRI. The 123I-MIBG scan was positive for this lesion and, in addition, another uptake was observed located caudally at the level of L5 and of smaller size and less intensity. The second lesion was not considered for surgical removal, due to its lack of morphological definition. One week after surgical intervention, the patient presented difficult-to-control high blood pressure. A second 123I-MIBG scan was performed. The previously described second image was more intense in this study, and surgery was planned to remove it. A combination of techniques including freehand-SPECT and a portable hybrid gamma camera (with optical camera) were used pre-operatively to identify the location of the lesion. The combination of intra-operative laparoscopic gamma probe and portable hybrid gamma camera enabled the tumor to be located, excised, and its complete removal to be monitored. The histopathology analysis confirmed a second paraganglioma.

Correlation of 18F-FDG uptake on PET/CT with Ki67 immunohistochemistry in pre-treatment epithelial ovarian cancer. / Correlación de la captación de 18F-FDG de la PET/TC con el Ki67 de la inmunohistoquímica en el cáncer epitelial de ovario pretratamiento.

OBJECTIVE: Standardised uptake value (SUV) and volumetric parameters such as metabolic tumour volume (MTV) and total lesion glycolysis (TLG) from 18F-FDG PET/CT are useful criteria for disease prognosis in pre-operative and post-treatment epithelial ovarian cancer (EOC). Ki67 is another prognostic biomarker in EOC, associated with tumour aggressiveness. The aim of this study is to evaluate the association between 18F-FDG PET/CT measurements and Ki67 in pre-treatment EOC to determine if PET/CT parameters could non-invasively predict tumour aggressiveness. MATERIAL AND METHODS: A pre-treatment PET/CT was performed on 18 patients with suspected or newly diagnosed EOC. Maximum SUV (SUVmax), mean SUV (SUVmean), whole-body MTV (wbMTV), and whole-body TLG (wbTLG) with a threshold of 30% and 40% of the SUVmax were obtained. Furthermore, Ki67 index (mean and hotspot) was estimated in tumour tissue specimens. Immunohistochemical findings were correlated with PET parameters. RESULTS: The mean age was 57.0 years old (standard deviation 13.6 years). A moderate correlation was observed between mean Ki67 index and SUVmax (r=0.392), SUVmean 30% (r=0.437), and SUVmean 40% (r=0.443), and also between hotspot Ki67 index and SUVmax (r=0.360), SUVmean 30% (r=0.362) and SUVmean 40% (r=0.319). There was a weaker correlation, which was inversely negative, between mean and hotspot Ki67 and volumetric PET parameters. However, no statistical significant differences were found for any correlations. CONCLUSIONS: SUVmax and SUVmean were moderately correlated with Ki67 index, whereas volumetric PET parameters overall, showed a weaker correlation. Thus, SUVmax and SUVmean could be used to assess tumour aggressiveness in pre-treatment EOC.

Radioguided surgery and the GOSTT concept: From pre-operative image and intraoperative navigation to image-assisted excision / Cirugía radioguiada y concepto GOSTT: desde la imagen preoperatoria y la navegación inatraoperatoria hacia la resección asistida por imagen

Radio-guided surgery has been developed for application in those disease scheduled for surgical management, particularly in areas of complex anatomy. This is based on the use of pre-operative scintigraphic planar, tomographic and fused SPECT/CT images, and the possibility of 3D reconstruction for the subsequent intraoperative locating of active lesions using handheld devices (detection probes, gamma cameras, etc.). New tracers and technologies have also been incorporated into these surgical procedures. The combination of visual and acoustic signals during the intraoperative procedure has become possible with new portable imaging modalities. In daily practice, the images offered by these techniques and devices combine perioperative nuclear medicine imaging with the superior resolution of additional optical guidance in the operating room. In many ways they provide real-time images, allowing accurate guidance during surgery, a reduction in the time required for tissue location and an anatomical environment for surgical recognition. All these approaches have been included in the concept known as (radio) Guided intraOperative Scintigraphic Tumour Targeting (GOSTT). This article offers a general view of different nuclear medicine and allied technologies used for several GOSTT procedures, and illustrates the crossing of technological frontiers in radio-guided surgery (AU)

La cirugía radioguiada ha sido desarrollada para su aplicación en enfermedades que requieren un manejo quirúrgico especial, principalmente en áreas de anatomía compleja. Esta serie de procedimientos requieren la realización de imágenes preoperatorias: gammagráficas planares, tomográficas y de fusión (SPECT/TC) y la posibilidad de reconstrucción 3D para la posterior localización intraoperatoria de las lesiones activas mediante dispositivos portátiles (sondas de detección, gammacámaras, etc.). Además, integra el uso de nuevos radiotrazadores que han sido incorporados como parte de esta nueva tecnología en los procedimientos quirúrgicos en la práctica asistencial. La combinación de las señales acústicas y visuales durante los procedimientos intraoperatorios ha sido posible gracias a los dispositivos de imagen portátil. En la práctica diaria las imágenes ofrecidas por estas técnicas y dispositivos combinan la imagen preoperatoria de medicina nuclear con la mayor resolución que ofrecen las imágenes ópticas, sirviendo de guía más veraz en el campo quirúrgico. La imagen proporcionada con estas técnicas y dispositivos ofrece información y guía hacia el objetivo en tiempo real, una reducción de tiempo para la localización del tejido marcado previamente y un entorno anatómico para el reconocimiento de la estructura tisular a resecar. Todos estos enfoques se engloban dentro del concepto conocido como (radio)Guided intraOperative Scintigraphic Tumor Targeting (GOSTT). En este artículo se ofrece una visión general de las distintas técnicas de medicina nuclear y las tecnologías afines para ser aplicadas en diferentes procedimientos de este tipo, e ilustra de manera especial el cruce de fronteras tecnológicas observado en la cirugía radioguiada (AU)

18F-FDG PET/CT and sentinel lymph node biopsy in the staging of patients with cervical and endometrial cancer. Role of dual-time-point imaging / PET/TC con 18F-FDG y biopsia del ganglio centinela en la estadificación de pacientes con cáncer de cérvix y endometrio. Utilidad de la imagen dual-time-point

Objective. Definitive staging for cervical (CC) and endometrial cancer (EC) takes place once surgery is performed. The aim of this study was to evaluate the role of PET/CT in detecting lymphatic metastasis in patients with CC and EC using dual-time-point imaging (DPI), taking the histopathological results of sentinel lymph node (SLN) and lymphadenectomy as the reference. Material and methods. A prospective study was conducted on 17 patients with early CC, and 13 patients with high-risk EC. The patients had a pre-operative PET/CT, MRI, SLN detection, and lymphadenectomy, when indicated. PET/CT findings were compared with histopathological results. Results. In the pathology study, 4 patients with CC and 4 patients with EC had lymphatic metastasis. PET/CT showed hypermetabolic nodes in 1 patient with CC, and 5 with EC. Four of these had metastasis, one detected in the SLN biopsy. Four patients who had negative PET/CT had micrometastasis in the SLN biopsy, 1 patient with additional lymph nodes involvement. The overall patient-based sensitivity, specificity, positive and negative predictive values, and accuracy of PET/CT to detect lymphatic metastasis was 20.0%, 100.0%, 100.0%, 87.9%, and 88.2%, respectively, in CC, and 57.1%, 88.9%, 66.7%, 84.2% and 80.0%, respectively, in EC. DPI showed higher retention index in malignant than in inflammatory nodes, although no statistically significant differences were found. Conclusions. PET/CT has low sensitivity in lymph node staging of CC and EC, owing to the lack of detection of micrometastasis. Thus, PET/CT cannot replace SLN biopsy. Although no statistically significant differences were found, DPI may help to differentiate between inflammatory and malignant nodes (AU)

Objetivo. La estadificación definitiva del cáncer de cérvix (CC) y de endometrio (CE) tiene lugar tras la cirugía. Nuestro objetivo fue evaluar la utilidad de la PET/TC para la detección de metástasis ganglionares en el CC y en el CE con imagen dual-time-point (DPI), considerando como gold standard la histopatología del ganglio centinela (GC) y la linfadenectomía. Material y métodos. Diecisiete pacientes con CC inicial y 13 con CE de alto riesgo fueron incluidas prospectivamente. Preoperatoriamente se realizó una PET/TC, RM, detección del GC y linfadenectomía en los casos indicados. Se comparó la PET/TC con la histopatología. Resultados. En el estudio anatomopatológico, 4 pacientes con CC y 4 con CE tuvieron metástasis ganglionares. La PET/TC mostró ganglios hipermetabólicos en una paciente con CC y en 5 con CE. Cuatro de ellas tenían metástasis, una detectada en el GC. Cuatro pacientes con PET/TC negativa presentaron micrometástasis en el GC, una paciente con ganglios adicionales infiltrados. La sensibilidad, especificidad, valor predictivo positivo y negativo y la exactitud diagnóstica de la PET/TC para detectar metástasis ganglionares fueron 20,0; 100,0; 100,0; 87,9 y 88,2% para el CC, y 57,1; 88,9; 66,7; 84,2 y 80,0% para el CE. La DPI mostró un índice de retención superior en ganglios infiltrados respecto a los inflamatorios, sin hallar diferencias estadísticamente significativas. Conclusiones. La PET/TC tiene baja sensibilidad para estadificar el CC y CE por la incapacidad de detectar micrometástasis y, por tanto, no sustituye la detección del GC. Aunque no hubo diferencias estadísticamente significativas, la DPI podría ayudar a diferenciar ganglios inflamatorios de tumorales (AU)

Health-related quality of life of rheumatic disease patients treated in a specialized IPS in Medellin, Colombia.

PURPOSE: To compare Health-Related Quality of Life (HRQOL) profiles and their associated factors in people with rheumatoid arthritis (RA), spondyloarthritis (SpA), fibromyalgia (FM) and rheumatoid comorbidity treated in a specialized health center (SHC) in Medellin, Colombia. METHODS: A cross-sectional analytical study was performed with 93 RA patients, 30 SpA patients, 41 primary FM patients and 48 secondary FM patients with a concurrent diagnosis of RA or SpA. A demographic, socioeconomic, and clinical survey (the IPAQ, International Physical Activity Questionnaire) and the SF-36 survey validated in Medellin were administered. The statistical analyses were executed using SPSS 21.0 Results. Significant differences were found in all HRQOL dimensions among the patients, with physical performance perceived as the worst in the four groups. FM had the worst HRQOL profile, whereas the least affected group was SpA. Patients with RA and rheumatoid comorbidity shared similar HRQOL scores. The years of study, age and economic satisfaction variables were associated with the physical performance, vitality, social functioning, and mental health domains. CONCLUSION: The HRQOL profile was negative in patients with rheumatic diseases and lower in patients with FM. Additionally, variables or subgroups with greater deterioration were identified. This information will be useful for health activities and generate evidence in favor of incorporating HRQOL measurements into rheumatology services to complement clinical evaluations.

18F-FDG PET/CT and sentinel lymph node biopsy in the staging of patients with cervical and endometrial cancer. Role of dual-time-point imaging.

OBJECTIVE: Definitive staging for cervical (CC) and endometrial cancer (EC) takes place once surgery is performed. The aim of this study was to evaluate the role of PET/CT in detecting lymphatic metastasis in patients with CC and EC using dual-time-point imaging (DPI), taking the histopathological results of sentinel lymph node (SLN) and lymphadenectomy as the reference. MATERIAL AND METHODS: A prospective study was conducted on 17 patients with early CC, and 13 patients with high-risk EC. The patients had a pre-operative PET/CT, MRI, SLN detection, and lymphadenectomy, when indicated. PET/CT findings were compared with histopathological results. RESULTS: In the pathology study, 4 patients with CC and 4 patients with EC had lymphatic metastasis. PET/CT showed hypermetabolic nodes in 1 patient with CC, and 5 with EC. Four of these had metastasis, one detected in the SLN biopsy. Four patients who had negative PET/CT had micrometastasis in the SLN biopsy, 1 patient with additional lymph nodes involvement. The overall patient-based sensitivity, specificity, positive and negative predictive values, and accuracy of PET/CT to detect lymphatic metastasis was 20.0%, 100.0%, 100.0%, 87.9%, and 88.2%, respectively, in CC, and 57.1%, 88.9%, 66.7%, 84.2% and 80.0%, respectively, in EC. DPI showed higher retention index in malignant than in inflammatory nodes, although no statistically significant differences were found. CONCLUSIONS: PET/CT has low sensitivity in lymph node staging of CC and EC, owing to the lack of detection of micrometastasis. Thus, PET/CT cannot replace SLN biopsy. Although no statistically significant differences were found, DPI may help to differentiate between inflammatory and malignant nodes.

Radioguided surgery and the GOSTT concept: From pre-operative image and intraoperative navigation to image-assisted excision.

Radio-guided surgery has been developed for application in those disease scheduled for surgical management, particularly in areas of complex anatomy. This is based on the use of pre-operative scintigraphic planar, tomographic and fused SPECT/CT images, and the possibility of 3D reconstruction for the subsequent intraoperative locating of active lesions using handheld devices (detection probes, gamma cameras, etc.). New tracers and technologies have also been incorporated into these surgical procedures. The combination of visual and acoustic signals during the intraoperative procedure has become possible with new portable imaging modalities. In daily practice, the images offered by these techniques and devices combine perioperative nuclear medicine imaging with the superior resolution of additional optical guidance in the operating room. In many ways they provide real-time images, allowing accurate guidance during surgery, a reduction in the time required for tissue location and an anatomical environment for surgical recognition. All these approaches have been included in the concept known as (radio) Guided intraOperative Scintigraphic Tumour Targeting (GOSTT). This article offers a general view of different nuclear medicine and allied technologies used for several GOSTT procedures, and illustrates the crossing of technological frontiers in radio-guided surgery.

Oropharyngeal airway dimensions after treatment with functional appliances in class II retrognathic children.

Class II skeletal malocclusion and respiratory disorders owing to the obstruction of the upper airway at early growth stages have been correlated. The retro/micrognathism can be treated with functional appliances. However, the effects of an early functional orthopedic treatment on the airway dimensions have not been evaluated before the growth peak. Therefore, the objective of this study was to evaluate the changes in the airway dimensions of class II retrognathic children who received treatment with either Klammt or Bionator on a pre-pubertal stage. The sample consisted of 50 lateral cephalograms of class II retrognathic patients in a pre-puberal stage, before and after the use of a Klammt or Bionator II treatment for 1 year. The data were evaluated by Student's t-test or Mann-Whitney test, and significance was set at 5% (P < 0·05). When the measurements before and after treatment were compared, a statistically significant increase in the airway dimensions was found at the space where the adenoid tissue was located. The only airway dimensions that increased after treatment with functional appliances were the ones located at the nasopharynx. The adenoid tissue is still in the peak of growing at the ages of the subjects included in this study. However, the measurements along the nasopharynx increased when compared with the initial ones. Still, similar retrospective and prospective studies are needed at older stages.

Analysis of the expression of the Rhodobacter sphaeroides lexA gene.

The regulation of the Rhodobacter sphaeroides lexA gene has been analyzed using both gel-mobility experiments and lacZ gene fusions. PCR-mediated mutagenesis demonstrated that the second GAAC motif in the sequence GAACN7GAACN7GAAC located upstream of the R. sphaeroides lexA gene is absolutely necessary for its DNA damage-mediated induction. Moreover, mutagenesis of either the first or the third GAAC motif in this sequence reduced, but did not abolish, the inducibility of the R. sphaeroides lexA gene. A R. sphaeroides lexA-defective (Def) mutant has also been constructed by replacing the active lexA gene with an inactivated gene copy constructed in vitro. Crude extracts of the R. sphaeroides lexA(Def) strain are unable to form any protein-DNA complex when added to the wild-type lexA promoter of R. sphaeroides. Likewise, the R. sphaeroides lexA(Def) cells constitutively express the recA and lexA genes. All these data clearly indicate that the lexA gene product is the negative regulator of the R. sphaeroides SOS response. Furthermore, the morphology, growth and viability of R. sphaeroides lexA(Def) cultures do not show any significant change relative to those of the wild-type strain. Hence, R. sphaeroides is so far the only bacterial species whose viability is known not to be affected by the presence of a lexA(Def) mutation.

Bacillus subtilis LrpC is a sequence-independent DNA-binding and DNA-bending protein which bridges DNA.

Genetic evidence suggests that the Bacillus subtilis lrpC gene product participates in cell growth and sporulation. The purified LrpC protein, which has a predicted molecular mass of 16.4 kDa, is a tetramer in solution. LrpC binds with higher affinity ( K (app) approximately 80 nM) to intrinsically curved DNA than to non-curved DNA ( K (app) approximately 700 nM). DNase I footprinting and the supercoiling of relaxed circular plasmid DNA in the presence of topoisomerase I revealed that LrpC induces DNA bending and constrains DNA supercoils in vitro. The LrpC protein cooperatively increases DNA binding of the bona fide DNA-binding and DNA-bending protein Hbsu. LrpC forms inter- and intramolecular bridges on linear and supercoiled DNA molecules, resulting in a large network and DNA compactation. Collectively, these findings suggest that LrpC is an architectural protein and that its activities could provide a means to modulate DNA transactions.

Regulation of divergent transcription from the uvrA-ssb promoters in Sinorhizobium meliloti.

The Sinorhizobium meliloti uvrA gene was isolated by complementation of a Rhodobacter sphaeroides UvrA- mutant. DNA sequencing of the region upstream of the S. meliloti uvrA gene reveals the presence of the ssb gene in the opposite transcriptional orientation. PCR-mediated mutagenesis demonstrated that expression of these two genes is inducible by DNA damage, and depends, in both cases, on the direct repeat GTTCN7GTTC (cited according to the direction of uvrA transcription). Comparison of the sequences of recA and uvrA promoters from different bacterial species of the alpha group of the Proteobacteria has identified the direct repeat GTTCYYKTTTTGTTC as the SOS box in this phylogenetic group.

Mutational analysis of the Rhizobium etli recA operator.

Based upon our earlier studies (A. Tapias, A. R. Fernández de Henestrosa, and J. Barbé, J. Bacteriol. 179:1573-1579, 1997) we hypothesized that the regulatory sequence of the Rhizobium etli recA gene was TTGN11CAA. However, further detailed analysis of the R. etli recA operator described in the present work suggests that it may in fact be GAACN7GTAC. This new conclusion is based upon PCR mutagenesis analysis carried out in the R. etli recA operator, which indicates that the GAAC and GTAC submotifs found in the sequence GAACN7GTAC are required for the maximal stimulation of in vivo transcription and in vitro DNA-protein complex formation. This DNA-protein complex is also detected when the GAACN7GTAC wild-type sequence is modified to obtain GAACN7GAAC, GTACN7GTAC, or GAACN7GTTC. The wild-type promoters of the Rhizobium meliloti and Agrobacterium tumefaciens recA genes, which also contain the GAACN7GTAC sequence, compete with the R. etli recA promoter for the DNA-protein complex formation but not with mutant derivatives in any of these motifs, indicating that the R. etli, R. meliloti, and A. tumefaciens recA genes present the same regulatory sequence.

Identification of the Rhodobacter sphaeroides SOS box.

Gel-mobility shift assays with crude cell extracts of Rhodobacter sphaeroides, which belongs to the alpha group of the proteobacteria, have shown that a protein binds to the promoter of its recA gene, resulting in two retardation bands. Analysis of the minimal region of the R. sphaeroides recA gene required for the formation of the DNA-protein complexes, revealed the presence of the motifs GTTCN7GATC and GAACN7GAAC, which are centred at positions -21 and +8 from the transcriptional starting point respectively. Using PCR mutagenesis, we have demonstrated that these two motifs are required for the formation of both DNA-protein complexes in vitro as well as for the DNA damage-mediated inducibility of the recA gene in vivo. Furthermore, the level of the recA gene expression in the constitutive mutants is the same as that achieved by the wild-type cells after DNA damage, indicating that the binding protein must be a repressor. The motif GTTCN7GTTC is also present upstream of the R. sphaeroides uvrA promoter, which in vitro specifically binds to a protein and whose expression is DNA damage inducible. Mutagenesis of this motif abolishes both the binding of this protein to the uvrA promoter and the DNA damage-mediated expression of this gene. The fact that the recA and uvrA wild-type promoters compete with each other for the retardation band formation, but not with their mutant derivatives in any of these motifs, indicates that the same repressor binds to the operator of both genes. All these results lead us to propose the sequence GTTCN7GTTC as the SOS box of R. sphaeroides. This is the first SOS box known whose sequence is a direct repeat and not a palindrome.

Local repolarization abnormalities induced by transcatheter radiofrequency ablation in pigs.

Radiofrequency (RF) ablation alters action potential repolarization of myocardial cells and, theoretically, this should induce ST-T segment changes in the ECG. Since these ECG abnormalities have been rarely reported in patients submitted to RF ablation we assess the ability of the procedure to cause ST-T segment changes in local electrograms. Epicardial ECG mapping was performed in 17 anesthetized open chest pigs submitted to endocardial (n = 9) or to epicardial (n = 8) unipolar radiofrequency ablation (500 kHz, 20 W for 5-10 s). To characterize the cellular electrophysiological alterations induced by RF ablation transmembrane action potentials were recorded at various distances from the ablation lesion; these were compared with seven control pigs. Endocardial RF ablation induced a transient (< 5 min) change of 6.1 +/- 2.4 mV in T wave amplitude (baseline: 12.8 +/- 5.6 mV, P < 0.001) in 141 out of 269 epicardial electrodes. T wave changes were associated with shortening in local activation time (20.1 +/- 2.3 ms at baseline vs 18.5 +/- 2.5 ms at 60 s after ablation, P = 0.03). RF current caused persistent St segment elevation at the center of the ablation lesion with no transmural expansion. Intracellular potentials along a 2-6 mm wide myocardial band bordering the RF lesion lower amplitude (101 +/- 7.0 mV vs 71 +/- 23 mV, P < 0.01) and shorter duration (254 +/- 44 ms vs 156 +/- 29 ms, P < 0.01) than control hearts. The center of the ablation lesion was electrically unexcitable. We concluded that RF ablation alters cellular electrophysiology in small areas surrounding the ablation lesion and this causes short-lasting transmural changes in T 3 wave amplitude and nontransmural ST segment elevation.

Characterization of the promoter of the Rhizobium etli recA gene.

The promoter of the Rhizobium etli recA gene has been identified by primer extension and by making deletions affecting several regions located upstream of its coding region. A gel mobility shift assay carried out with crude extracts of cells of R. etli has been used to show that a DNA-protein complex is formed in the R. etli recA promoter region in vitro. Analysis of the minimal region of the recA promoter giving rise to this DNA-protein complex revealed the presence of an imperfect palindrome corresponding to the sequence TTGN11CAA. Site-directed mutation of both halves of this palindrome indicated that both motifs, TTG and CAA, are necessary for both normal DNA-protein complex formation in vitro and full DNA damage-mediated inducibility of the recA gene in vivo. However, the TTG motif seems to be more dispensable than the CAA one. The presence of this same palindrome upstream of the recA genes of Rhizobium meliloti and Agrobacterium tumefaciens, whose expression is also regulated in R. etli cells, suggests that this TTGN11CAA sequence may be the SOS box of at least these three members of the Rhizobiaceae.

Lack of evidence of M-cells in porcine left ventricular myocardium.

OBJECTIVE: The aim of this study was to analyze whether cells with long action potential duration, fast Vmax, and spike-and-dome configuration (M-cells) are present in porcine left ventricular myocardium. METHODS: Transmembrane action potentials (n = 505) of the left ventricle were recorded with conventional glass microelectrodes in an epicardial-endocardial direction at 2000 ms basic cycle length in 14 pigs. In 3 pigs, potentials were obtained at 1000, 2000, and 5000 ms cycle length before and after superfusion with quinidine HCl 1 microgram/ml. In addition, transmembrane potentials (n = 52) were recorded in 4 dogs at 2000 ms cycle length to verify the ability of our protocol to detect M-cells. RESULTS: In pigs, action potential duration at 90% repolarization was shorter (ANOVA, P < 0.001) and Vmax slower (P < 0.001) in the epicardium than in the other transmural sites, but there were no regional differences in resting membrane potential or in action potential amplitude. Potentials with particularly long phase 3 or with spike-and-dome configuration were not observed. All myocardial sites displayed rate dependence of action potential duration (P = 0.02) which was transmurally homogeneous and persisted after quinidine exposure. The drug did not induce afterdepolarizations. In dogs, potentials with spike-and-dome configuration, long duration, and fast Vmax, like those described in M-cells, were detected in deep epicardial and midmyocardial areas. CONCLUSION: The porcine left ventricular myocardium shows transmural differences in action potential duration and Vmax, but, unlike dogs, it lacks M-cells.

ST segment elevation at the surface of a healed transmural myocardial infarction in pigs. Conditions for passive transmission from the ischemic peri-infarction zone.

BACKGROUND: Ischemia of the myocardium surviving an infarction induces ST segment elevation in infarct-related ECG leads. In cases with no viable tissues, ischemia adjacent to the infarction could induce a similar ECG pattern if there is ST segment potential transmission through the necrotic scar. We analyzed whether acute ischemia adjacent to a healed infarction with no viable tissue may induce ST segment elevation on the surface of the necrotic scar. METHODS AND RESULTS: Epicardial ST segment changes elicited during 30 minutes of acute reocclusion of the left anterior descending (LAD) coronary artery 2 cm above the first diagonal branch were analyzed by 32-channel mapping in 18 chloralose-anesthetized open-chest pigs with 1-month-old anterior infarctions induced by permanent ligature below the first diagonal branch (group 1). The effect of a previous infarction on the magnitude of ischemic ST segment changes was assessed by similar mapping in 21 control pigs submitted to a LAD ligature 2 cm above the first diagonal branch (group 2, n = 11) or just below this branch (group 3, n = 10). Myocardial perfusion after coronary ligature was estimated in 7 pigs with chronic infarction and in 3 control pigs by mapping of myocardial technetium-99m-methoxyisobutyl isonitrile (99mTc-MIBI) activity in transmural samples underlying each epicardial electrode. The width of cell layers surviving the infarction was measured and their viability after 60 minutes of coronary reocclusion was assessed by intracellular glycogen staining. Reocclusion of the LAD induced parallel ST segment elevation at the periinfarction zone and at the necrotic scar, although in the latter region the changes were less marked (maximal ST segment, 8.4 +/- 3.0 mV versus 2.7 +/- 1.8 mV, ANOVA, P < .001). ST segment elevation inside the scar was greater at the margins (3.9 +/- 1.8 mV) than at sites 20 mm toward the center (2.8 +/- 1.7 mV, P = .003). The necrotic area was virtually devoid of surviving cells except for a 0.22 +/- 0.04-mm-wide subendocardial band that continued to show a positive intracellular glycogen reaction after the second LAD ligature. Acute ischemia adjacent to the infarction (group 1) induced lower ST segment elevation than acute ischemia at a comparable cardiac region in noninfarcted pigs (group 2) (ANOVA, P = .02), despite the fact that these areas developed similar underperfusion after coronary occlusion (percent MIBI activity of that in normal myocardium, 7 +/- 8 versus 7 +/- 6, P = NS). ST segment changes in group 2 pigs were comparable to those induced in group 3 pigs with a 2-cm-lower coronary occlusion. CONCLUSIONS: Acute ischemia adjacent to a chronic infarction induces ST segment elevation at the surface of the scar despite the virtual absence of viable tissue within the infarction. Data suggest a passive ST segment potential transmission through the infarction. Moreover, ischemia adjacent to a chronic infarction induces lower ST segment elevation than ischemia not adjacent to a necrosis. The mechanisms accounting for these regional differences are probably independent of collateral myocardial perfusion and ischemia extension.

Interspecies regulation of the recA gene of gram-negative bacteria lacking an E. coli-like SOS operator.

The recA genes of Agrobacterium tumefaciens, Rhizobium meliloti, Rhizobium phaseoli and Rhodobacter sphaeroides, species belonging to the alpha-group bacteria of the Proteobacteria class, have been fused in vitro to the lacZ gene of Escherichia coli. By using a mini-Tn5 transposon derivative, each of these recA-lacZ fusions was introduced into the chromosome of each of the four species, and into that of E. coli. The recA genes of three of the alpha bacteria are induced by DNA damage when inserted in A. tumefaciens, R. phaseoli or R. meliloti chromosomes. The expression of the recA gene of R. sphaeroides is DNA damage-mediated only when present in its own chromosome; none of the genes is induced in E. coli. Likewise, the recA gene of E. coli is not induced in any of the four alpha species. These data indicate that A. tumefaciens, R. meliloti and R. phaseoli possess a LexA-like repressor, which is able to block the expression of their recA genes, as well as that of R. sphaeroides, but not the recA gene of E. coli. The LexA repressor of R. sphaeroides does not repress the recA gene of A. tumefaciens, R. meliloti, R. phaseoli or E. coli.