A closed-chest model of selective atrial myocardial infarction for the study of induced electrophysiological and structural derangements

Background

The diagnosis of atrial infarction is often masked by the frequent association with ventricular infarction. For this reason, the electrophysiological and structural consequences of selective atrial ischemia are poorly understood.

Purpose

The objective of this study was to analyze the alterations in the ECG, local electrograms, and multifrequential atrial myocardial impedance in a new experimental model of acute and chronic atrial infarction.

Methods

Seven anesthetized pigs were subjected to 4h of atrial ischemia induced by selective catheter occlusion of the atrial coronary branches originating in the left circumflex coronary artery. The surface ECG was recorded and the changes in P-wave morphology analyzed. Four weeks later the animals were subjected to endocardial voltage mapping (Carto) and multifrequential impedance. The hearts were processed for anatomopathological study.

Results

Selective occlusion of the coronary atrial branches induced atrial infarction with fibrosis in the left atrium in 6 of the 7 cases (Figure). The surface ECG showed prolongation of the P-wave duration (Figure) (P-wave in lead II: from 72±8ms at baseline vs. 97±18ms at 4 weeks, ANOVA p<0.01; P-wave in lead aVR: from 71±3ms at baseline vs 87±9ms at 4 weeks, ANOVA p<0.01) with no appreciable displacement of the PR segment. Endocardial mapping of the left atrium showed low-voltage bipolar zones with decreased multi-frequency impedance phase angle values, as compared with preserved zones of the same atrium (bipolar electrograms: from 0.6±1mV to 2.0±1.9mV, T-Test p<0.01; Phase angle at 300KHz: from −5.5±2° to −9.0±4.4° T-Test p<0.05).

Conclusion

We developed a closed-chest swine model of selective atrial infarction suitable for the study of ECG patterns and electrophysiological mechanisms linked to atrial myocardial ischemia and infarction. The structural derangements are detectable by endocardial mapping of local voltage electrograms and local tissue impedance.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by grants from ISCI-MINECO (FIS PI17/00069), FEDER, CIBERCV (CB16/11/00276)

Real-time electrophysiological characterization of acute and chronic radiofrequency ablation lesions

Background

Assessment of lesion formation remains one of the most important goals to guide radiofrequency (RF) procedures in the cardiac electrophysiology laboratory. Cardiac navigation systems use specific algorithms to predict the effective lesion size, but these metrics are based only on ablation parameters and ignore local electric tissue characteristics. [1] Recent studies show that local multiparametric impedance is influenced by the intrinsic structural characteristics of the tissue. [2]

Purpose

This study aimed to assess the ability of local multiparametric impedance to characterize acute and chronic RF ablation lesions in the right atrium of pigs.

Methods

Four anesthetized closed-chest pigs were submitted to two interventions. The first intervention aimed at creating RF ablation lesions (30W, 60s, 55°) in the right atrium using an electrocatheter connected to a conventional cardiac navigation system, while mapping the local multiparametric impedance (LMI), the generator impedance (GI) and the bipolar voltage (BiV). All RF ablation lesions were performed with a stable contact force. Four weeks later, the second intervention aimed at mapping again the previous ablation sites. After the second intervention animals were euthanized and the hearts were removed and processed to identify the presence of fibrosis in the previously ablated lesions (Figure).

Results

We performed 19 ablations (5±2 per animal) with an average contact force of 14.2±4.6g. Four weeks later, 14/19 (74%) ablation lesions were identified as fibrotic points in the explanted heart (Figure 1). These showed decreased acute LMI and BiV values that persisted low after 4 weeks (Table 1). The remaining 5/19 ablations that did not present fibrosis had lower baseline LMI and bipolar values that resulted in lower LMI and BiV drops (Table 1). The absolute drop in LMI between effective and non-effective lesions was around 50%, while GI drop was only 21% (LMI drop @51KHz: From −3.0±1.4° to −1.5±0.3°, T-TEST p<0.05; GI drop: From 12.7±27.6Ω to 10.5±21.3Ω, T-TEST p=0.89).

Conclusion

The local baseline electrical properties of atrial myocardium are directly related to the effectiveness of RF ablation lesions. RF ablation sites that resulted into persistent fibrosis points had larger LMI and BiV values, with higher absolute drops than non-effective lesions. The use of LMI in clinical practice could improve the outcome of the procedures of arrhythmia ablation in the electrophysiology lab.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by grants from ISCI-MINECO (FIS PI21/00392), FEDER, CIBERCV (CB16/11/00276)

Dolutegravir plus rilpivirine: benefits beyond viral suppression: DORIPEX retrospective study

Switching dual therapy with dolutegravir (DTG) plus rilpivirine (RPV) was assessed in the SWORD-1 and SWORD-2 studies. Real-life data regarding the immunological impact of this approach on CD4+ and CD8+ T lymphocyte counts and the CD4/CD8 ratio are scarce. We evaluated this strategy on the basis of clinical practice data.A multicentric retrospective cohort study.Treatment-experienced virologically suppressed HIV-1-infected patients who were switched to DTG plus RPV were included. Using different models for paired data, we evaluated the efficacy and immune status in terms of CD4+ and CD8+ T-cell counts and CD4/CD8 ratio at 24 and 48 weeks of treatment.The study population comprised of 524 patients from 34 centers in Spain. Men accounted for 76.9% of patients, with a median age of 53 years. Patients receiving DTG plus RPV reached weeks 24 and 48 in 99.4% and 83.8% of cases, respectively, with only three (0.57%) virological failures. We found a significant decrease in CD8+ T-cell count (log OR -40) at week 24 and an increase in CD4+ T-cell count at week 48 (log OR +22.8). In acquired immunodeficiency syndrome-diagnosed patients, we found a significant increase in the CD4+ T-cell count at week 48 (log OR = 41.7, P = .0038), but no significant changes in the CD8+ T-cell count (log OR = -23.4, P = .54). No differences were found in the CD4/CD8 ratio between the acquired immunodeficiency syndrome subgroup and sex or age.In patients with controlled treatment, dual therapy with DTG plus RPV slightly improved the immune status during the first 48 weeks after switching, not only in terms of CD4+ T-cell count but also in terms of CD8+ T-cell count, with persistently high rates of viral control.

Sex-related differences of fatty acid-binding protein 4 and leptin levels in atrial fibrillation

AIMS

Adiposity plays a key role in the pathogenesis of atrial fibrillation (AF). Our aim was to study the sex differences in adipokines levels according to AF burden.

METHODS AND RESULTS

Two independent cohorts of patients were studied: (i) consecutive patients with AF undergoing catheter ablation (n = 217) and (ii) a control group (n = 105). (i) Adipokines, oxidative stress, indirect autonomic markers, and leucocytes mRNA levels were analysed; (ii) correlation between biomarkers was explored with heatmaps and Kendall correlation coefficients; and (iii) logistic regression and random forest model were used to determine predictors of AF recurrence after ablation. Our results showed that: (i) fatty acid-binding protein 4 (FABP4) and leptin levels were higher in women than in men in both cohorts (P < 0.01). In women, FABP4 levels were higher on AF cohort (20 ± 14 control, 29 ± 18 paroxysmal AF and 31 ± 17 ng/mL persistent AF; P < 0.01). In men, leptin levels were lower on AF cohort (22 ± 15 control, 13 ± 16 paroxysmal AF and 13 ± 11 ng/mL persistent AF; P < 0.01). (ii) In female with paroxysmal AF, there was a lower acetylcholinesterase and higher carbonic anhydrase levels with respect to men (P < 0.05). (iii) Adipokines have an important role on discriminate AF recurrence after ablation. In persistent AF, FABP4 was the best predictor of recurrence after ablation (1.067, 95% confidence interval 1-1.14; P = 0.046).

CONCLUSION

The major finding of the present study is the sex-based differences of FABP4 and leptin levels according to AF burden. These adipokines are associated with oxidative stress, inflammatory and autonomic indirect markers, indicating that they may play a role in AF perpetuation.

Prevalence of autosomal dominant polycystic kidney disease in Persian and Persian-related cats in Brazil

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic disease in cats. However, scarce data on its prevalence are available in Brazil. Persian cats and Persian-related breeds were assessed by molecular genotyping for a C to A transversion in exon 29 of PKD1 gene to determine ADPKD prevalence in a Brazilian population. Genomic DNA extracted from peripheral whole blood or oral swabs samples was used to amplify exon 29 of PKD1 gene employing a PCR-RFLP methodology. From a total of 616 animals, 27/537 Persian and 1/17 Himalayan cats showed the single-nucleotide variant (C to A) at position 3284 in exon 29 of feline PKD1. This pathogenic variation has been identified only in heterozygous state. The prevalence of ADPKD in Persian cats and Persian-related breeds was 5.03% and 1.6%, respectively. There was no significant association between feline breed, gender or age with ADPKD prevalence. Of note, the observed ADPKD prevalence in Persian cats and Persian-related breeds in Brazil was lower than the ones reported in other parts of the world. This finding may be related to genetic counseling and consequent selection of ADPKD-free cats for reproduction.

Evaluation of Cytopathological Techniques for the Diagnosis of Canine Visceral Leishmaniosis with Lymph Node Samples

The identification of the parasite in cytological smears of lymph node aspirates is a widely applied technique for the direct diagnosis of Leishmania spp. infection, especially in endemic areas. Although very specific, this method has limited sensitivity, and improving the technique would be highly desirable. This study aimed to evaluate the efficacy of conventional smear cytology (SC), liquid-based cytology (LBC), cell block (CB) stained with haematoxylin and eosin (HE) and immunocytochemistry (ICC), and formalin-fixed paraffin wax-embedded tissue immunohistochemistry (FFPE-IHC) compared with serology and polymerase chain reaction for the diagnosis of canine visceral leishmaniosis (CVL) in lymphoid tissue. The use of a preservative medium and centrifugation for cytological samples reduced the number of unsatisfactory artefacts/background. Moreover, LBC allowed excellent cellular preservation and the application of ancillary techniques, such as CB and ICC. SC was the most accurate morphological diagnostic method (45.0%). CB-ICC alone or associated with SC demonstrated significantly higher sensitivity (70.0% and 72.0%, respectively) when compared with SC alone (34.00%). CB-ICC was found to be more effective in the detection of infected animals with mild clinical signs, similar to FFPE-IHC. The specificity and positive predictive value were similar between all methods. Finally, the detection limit for CB-ICC and SC + CB-ICC was identical (18.46 amastigotes/mm²). Our study suggests that CB-ICC is a promising tool for improvement of the cytopathological diagnosis of CVL and may be applied in routine epidemiological screening.

P1598Electrophysiological and structural characterization of acute atrial myocardial infarction

Background

Atrial myocardial infarction may be a risk for atrial fibrillation. However, the electrophysiological and structural characteristics of the infarcted atrial myocardium are not well known. This study aimed to analyse the changes in local atrial electrograms and myocardial structure in an experimental model of isolated atrial myocardial infarction.

Methods

Five anesthetized, open-chest pigs were submitted to 4 hours of acute atrial myocardial ischemia induced by direct surgical clamping of atrial coronary branches originating from the right coronary artery. In all cases, we recorded simultaneously the 12-lead surface electrocardiogram (ECG) and the epicardial mapping of local atrial electrograms (17 x 12.5 mm patches containing 128 electrodes, with 1 mm inter-electrode distance) in a region close to the occluded branches and in control non-treated atria. The changes in local atrial QRS-ST segment and the amplitude of the P-wave of the ECG were sequentially analysed (Figure). The hearts were removed and processed for anatomopathological examination.

Results

Selective atrial coronary branch occlusion induced a patchy atrial myocardial necrosis with an irregular and abrupt border zone (circled areas in the Figure). During the first 15 min of ischemia, the local atrial electrograms showed increasing R waves, widening of QRS complex, and ST segment elevation leading to monophasic potentials (maximal ST segment at 30 min: from 0.2±0.7 mV to 1.9±1.4 mV, ANOVA p<0.01). This period was followed by a phase of transient electrical recovery characterized by disappearance of monophasic potentials, reduction of ST segment elevation, and recovery of local electrical activation. After 60 min of occlusion, monophasic potentials reappeared and the magnitude of ST segment elevation decreased progressively during the ensuing 3 hours. The spatial transition from areas with monophasic potentials to normal electrograms encompassed 1 or 2 electrodes. The surface ECG showed increased duration of the P-wave (lead II at 3h occlusion: from 73.2±4.5 ms to 88.9±15.5 ms, ANOVA p<0.05) with absence of ST segment changes. Atrial arrhythmias were not observed.

Structural and electrical atrial changes

Conclusion

Selective occlusion of atrial coronary branches induced patchy atrial myocardial necrosis with abrupt anatomical and electrical border zone. The overt QRS and ST segment changes in local atrial electrograms resembled those described in acute ventricular myocardial ischemia, and were associated with widening of the P-wave on the surface ECG. Although acute ischemic arrhythmias were not observed, the atrial structural alterations might set the substrate for re-entrant arrhythmias late after the healing over process.

Acknowledgement/Funding

Supported by grants from ISCI-MINECO (FISPI17/00069), CIBERCV (CB16/11/00276), FEDER and Fundaciό “La Maratό” TV3 (20150830).

P2431Stay on the safe side: in-silico assessment of ablation protocols to prevent steam pops during radiofrequency ablation

Background

Steam pops (SP) are among the most serious complications of radiofrequency ablation (RFA) due to its potential to cause myocardial tear or tamponade. SP occur when the tissue overheats, causing its water content to transform into steam and explode. Ablation parameters are critical in order to obtain an optimal lesion size while avoiding the occurrence of SP. However, the interaction between ablation settings and the physical parameters that predispose to SP occurrence during irrigated RFA are not fully understood.

Purpose

To characterize regularly used ablation protocols by means of a computational model, in order to achieve optimal lesion size while avoiding SP occurrence.

Methods

The in-silico evaluation is performed using our previously developed computational irrigated RFA model. Our model takes into account the blood-saline interaction as well as the mechanical deformation of the tissue due to the contact with the catheter tip. We test the effects of applied power and contact force on two catheter tip designs (spherical and cylindrical) and two substrates, simulated human atrium and ventricle, during 30 sec applications. A fixed blood flow and catheter-tip saline irrigation (0.5m/s and 17mL/min, respectively) are considered. We simulate human tissue by using the biophysical, mechanical and physiological properties found in the literature. SP occurrence is predicted when the temperature within the tissue reaches 100°C.

Results

Based on the interaction of power and contact force, four risk maps are constructed encompassing the two catheter-tip designs and the two simulated tissues. The maps allow the identification of those ablation protocols (contact force and delivered power) that can potentially result on SP. They correspond to that area of critical temperature values where the temperature within the tissue reach the established criteria for SP occurrence. We also present the lesion size dimensions of ablation protocols that avoid the formation of steam pops.

Conclusion

Our results indicate that the applied power has a strong impact in the formation of SP for a cylindrical catheter, while a combination of contact force and power is important to avoid risks in the case of the spherical catheter tip. The tissue characteristics do not affect significantly the SP occurrence, in agreement with experimental literature. However, the resulting lesion size appears to be larger in the simulated human atrium in comparison to the simulated human ventricle.

Acknowledgement/Funding

BERC 2018-2021, SEV-2017-0718

Cutaneous schistosomiasis and leishmaniasis coinfection: a case report

BACKGROUND

The polymorphic clinical presentations of schistosomiasis and leishmaniasis allow their inclusion in the differential diagnoses of several conditions. Although an overlap in distribution of these diseases has been reported in endemic areas, coinfection with cutaneous schistosomiasis and cutaneous leishmaniasis in the same patient is rare.

OBJECTIVES

We report an unusual case of concomitant cutaneous schistosomiasis and cutaneous leishmaniasis. Actions for the management and diagnosis were proposed.

METHODS

A patient presented with cutaneous lesions on the abdomen and left elbow. The presence of degenerated ova of Schistosoma mansoni in the skin biopsy led to perform a complementary investigation with immunohistochemical techniques, rectal biopsy and abdominal ultrasonography. After the left elbow lesions had failed to improve after several weeks of standard treatment, a new biopsy was performed and led to diagnosis of another infection.

RESULTS

The patient lived in an endemic area for two infectious diseases (schistosomiasis and leishmaniasis). Biopsies revealed chronic granulomatous dermatitis. Degenerated S. mansoni eggs were found in the abdominal lesion and in a rectal biopsy specimen. Ultrasonography revealed hepatic involvement. Despite combination treatment with oxamniquine and praziquantel, a cutaneous lesion persisted on the left elbow; a new biopsy revealed amastigote forms of Leishmania. The patient was successfully treated with intramuscular and intralesional meglumine antimoniate.

CONCLUSIONS

The presence of a similar granulomatous infiltrate in lesions caused by the two different infectious agents led to a delay in the diagnosis of cutaneous leishmaniasis. This report serves as a warning of the unusual possibility of cutaneous schistosomiasis and leishmaniasis coinfection in an endemic area.

Neoplasms of Unknown Primary Site: A Clinicopathological Study of Autopsied Patients

Background

Malignant neoplasms of an unknown primary site (NUPS) remain a diagnostic and therapeutic challenge in clinical practice. With this in mind, we have reviewed all autopsies performed in patients with NUPS in a single institution.

Patients and methods

By reviewing 1656 autopsies performed on adults in our Institution (1974-1990), 43 cases of NUPS were found. (NUPS was defined as histologically proven malignant tumor for which a primary site could not be found after anamnesis, complete physical examination, chest X-ray and routine chemistries.)

Results

There were 24 men (56 %) and 19 women. Mean age was 62 years (76 % of patients were aged 40-75). Clinical presentation included general deterioration (73 %), digestive symptoms (58 %), liver enlargement (58 %) abdominal pain (56 %), respiratory symptoms (45 %), ascites (26 %) and node enlargement (16 %). Abnormalities in analysis and image tests were frequent but nonspecific. Median time from admission to death was 42 days (range, 4-135). Pathologic diagnoses at autopsy were: 23 adenocarcinomas (53 %), arising from pancreas (6), biliary tree (6), lung (3), prostate (2), stomach (1), kidney (1) and unknown (4); 3 squamous carcinomas (5 %) (1 renal pelvis, 1 biliary tree, 1 stomach); 5 undifferentiated carcinomas (1 lung, 4 unknown); and 12 miscellaneous tumors (including 3 lymphomas, 3 neuroendocrine tumors, 3 hepatocarcinomas, 2 mesotheliomas and 1 melanoma). There was a tendency towards a metastatic pattern different from that expected from the primary tumor. Image tests were of little usefulness in the search for the primary tumor.

Conclusions

1) Adenocarciomas were the most frequent tumor presenting as NUPS, especially from the pancreas and biliary tree. 2) In this series, at least 11 % of patients were amenable to standard systemic therapies (3 lymphomas and 2 prostatic adenocarcinomas) if a correct pathologic diagnosis could have been established when alive. 3) Presenting symptoms and metastatic pattern differed from those expected for the primary neoplasm eventually found. 4) Image tests were often misleading as regards the primary site, although they were useful to quantify the dissemination of the tumor.

Multicentric cutaneous keratoacanthomas in a free-living marmoset (Callithrix sp.)

Cutaneous neoplasia is common in non-human primates. We describe the gross and microscopic features of multicentric cutaneous keratoacanthomas in a free-living marmoset (Callithrix sp.). Immunohistochemistry for human papillomavirus and herpes simplex virus type I and simplex virus type II was negative. Keratoacanthomas should be included in the differential diagnosis for cutaneous masses in non-human primates.

Parotid Salivary Gland Basal Cell Adenocarcinoma in a Big-eared Opossum (Didelphis aurita)

The opossum (family Didelphidae) is a marsupial endemic to the Americas. Apart from the South American short-tailed opossum (Monodelphis domestica) and the Virginia opossum (Didelphis virginiana), there is considerable lack of knowledge about the health and diseases of most opossum species. Among these, the big-eared opossum (Didelphis aurita) is found in Argentina, Brazil and Paraguay. Natural and experimental studies have shown this species to be susceptible to infectious agents with zoonotic potential and the animals may play a role in transmission of such agents. However, neoplasia appears to be uncommon in this species. We describe the gross, microscopical and immunohistochemical features of a parotid salivary gland basal cell adenocarcinoma in a free-living big-eared opossum. This case represents the first report of salivary gland neoplasia in opossums.

Spontaneous pulmonary adenosquamous carcinoma in a free-living black capuchin monkey (Sapajus nigritus)

Pulmonary neoplasia is rare among wild New World primates. We report the gross, microscopical, and immunohistochemical features of a primary multicentric pulmonary adenosquamous carcinoma in a free-living black capuchin monkey (Sapajus nigritus). Herein, the spectrum of pulmonary neoplasms in non-human primates is widened and briefly reviewed.

Liquid-based cytology and cell block immunocytochemistry in veterinary medicine: comparison with standard cytology for the evaluation of canine lymphoid samples

Liquid-based Cytology (LBC) consists of immediate wet cell fixation with automated slide preparation. We applied LBC, cell block (CB) and immunocytochemistry to diagnose canine lymphoma and compare results with conventional cytology. Samples from enlarged lymph nodes of 18 dogs were collected and fixed in preservative solution for automated slide preparation (LBC), CB inclusion and immunophenotyping. Two CB techniques were tested: fixed sediment method (FSM) and agar method (AM). Anti-CD79a, anti-Pax5, anti-CD3 and anti-Ki67 were used in immunocytochemistry. LBC smears showed better nuclear and nucleolar definition, without cell superposition, but presented smaller cell size and worse cytoplasmic definition. FSM showed consistent cellular groups and were employed for immunocytochemistry, while AM CBs presented sparse groups of lymphocytes, with compromised analysis. Anti-Pax-5 allowed B-cell identification, both in reactive and neoplastic lymph nodes. Our preliminary report suggests that LBC and FSM together may be promising tools to improve lymphoma diagnosis through fine-needle aspiration.

E-cadherin in canine mast cell tumors: decreased expression and altered subcellular localization in Grade 3 tumors

Mast cell tumors (MCTs) are the most frequent round cell tumors in dogs and comprise approximately 21% of all canine cutaneous tumors. MCTs are highly invasive and metastatic corresponding to the histological grade. E-cadherin is an adhesion molecule expressed in epithelial cells and although it is an epithelial cellular marker, studies have shown expression of E-cadherin in canine round cell tumors. To better characterize the expression pattern of E-cadherin in several different histological grades of MCTs in dogs, the expression and localization of the adhesion molecule was investigated using immunohistochemistry. For this purpose, 18 cutaneous MCTs were classified into three histological grades, 1, 2 or 3. Clinical history and follow-up data were available for all of the dogs. Cytoplasmic and nuclear expressions of E-cadherin in all three types of tumors were verified by immunostaining using two different antibodies. There was decreased E-cadherin expression in the more aggressive MCTs (Grade 3), suggesting an association between E-cadherin and tumor aggressiveness. Additionally, the loss of E-cadherin expression in either the cytoplasm or nucleus in more aggressive and undifferentiated tumor types confirmed the importance of cellular adhesion in tumor behavior.

Causes of ischemic stroke in young adults, and evolution of the etiological diagnosis over the long term

BACKGROUND

Causes of ischemic stroke in young adults (15-45 years) are diverse, but undetermined etiology is common in a majority of studies.

AIMS

The present series study aims to evaluate causes and changes in the etiological diagnosis of ischemic stroke in young adult patients admitted to a tertiary medical center over a period of 27 years.

METHODS

We retrospectively reviewed the records of patients with a first-ever stroke in the age range of 15-45 years who were admitted to the '12 de Octubre' University Hospital between 1974 and 2002.

RESULTS

272 young adults with ischemic stroke were identified. The etiological diagnoses were: undetermined in 36% of patients, large-artery atherosclerosis in 21%, cardioembolism in 17%, non-atherosclerotic vasculopathy in 17%, and other specific etiologies in 9%. While in the first study period (1974-1988) 45% of patients were diagnosed with uncertain etiology, in the last period (1989-2002) only 26% were diagnosed with cryptogenic stroke (45% with two or more potential etiologies identified; 45% with no identified cause despite complete evaluation, and 10% with incomplete evaluation).

CONCLUSIONS

The etiological diagnosis of stroke in young adults has changed over time as a result of improvements in diagnostic workup. While cryptogenic stroke was the most frequent diagnosis in the past, today specific causes (non-atherosclerotic vasculopathy, large-artery atherosclerosis, cardioembolism and hematological disorder) are identified in the majority of patients.

Evolution of the correlation between orthogonal polarization patterns in broad-area lasers

We measure polarization-resolved instantaneous patterns in a large-aspect ratio quasi-isotropic Nd:YAG laser. High correlation between the instantaneous orthogonal polarization patterns recorded at the earlier stages of the laser pulse has been found due to the strong cross saturation between both polarization modes.

Dynamic transition from modelike patterns to turbulentlike patterns in a broad-area Nd:YAG laser

We report the first experimental observation to our knowledge of a dynamic transition from modelike patterns to completely disordered patterns in a large-aspect-ratio Nd:YAG laser. Recordings of near-field patterns with an integration time as small as 1 ns allow us to follow the evolution of the transverse intensity profile along the output pulse of the laser.

Pseudomyxoma peritonei: a clinicopathologic analysis and follow-up of 21 patients

BACKGROUND/AIMS

Pseudomyxoma peritonei is an uncommon disease characterized by the presence of mucinous peritoneal implants associated with an abdominal neoplasm. Our objective is to consider the characteristics of this entity in our western Mediterranean urban population.

METHODOLOGY

All cases diagnosed with pseudomyxoma peritonei by our hospital during a period of 16 years were reviewed. Data from their clinical records and the biopsy samples were analyzed.

RESULTS

We found 21 cases of pseudomyxoma peritonei with a male/female ratio of 10/11 and a mean age of 59 years. The predominant presentation symptom was abdominal pain (17 cases, 6 of them with acute abdomen). The most frequent primary site of origin of the pseudomyxoma was the appendix (10 cases). The histologic diagnosis was malignant (associated with carcinoma) in 17 cases and indeterminate behavior in 4. The follow-up was available for 15 patients (mean follow-up of 41 months), while six patients have been lost. Nine patients have died during the follow-up and the other 6 patients are still alive after follow-up.

CONCLUSIONS

Laparotomy is the main tool for diagnosing pseudomyxoma peritonei. The appendix is the most frequent primary site of origin of pseudomyxoma peritonei, followed by bowel; the latter being more important than previously described. In most cases the histology is malignant. The prognosis is bad with a mortality greater than 60% at 5 years.

Long-term prognosis of ischemic stroke in young adults. Study of 272 cases

BACKGROUND

There have been few studies of the long-term prognosis of young adults with ischemic stroke. The present study aimed to evaluate the long-term clinical outcome in a large series of young adults with ischemic stroke admitted to a tertiary medical center over the last 27 years, and to identify possible predictors for mortality, stroke recurrence and poor functional recovery.

METHODS

We retrospectively reviewed 272 young adults (15-45 years) with a first-ever ischemic stroke admitted to the Neurology Department of University Hospital "12 de Octubre" between 1974 and 2001. Follow-up assessments were performed by review of medical records and telephone interviews.

RESULTS

Nine patients (3%) died as the result of their initial stroke and follow-up information about the status of 23 (8%) patients was not available. The remaining 240 patients (89%) were followed. Two hundred and ten of them (88%) were alive with a mean follow-up of 12.3 years and 30 (12%) died during follow-up. The average annual mortality rate was 1.4%, being notably higher during the first (4.9%) than in the subsequent years (0.9%) after the initial stroke. Ninety per cent of the followed patients were independent and 53% returned to work, although adjustments were necessary for 23% of them. The annual stroke recurrence rate during the first year was 3.6% dropping to 1.7% in subsequent years. Age over 35 years, male gender, the presence of cardiovascular risk factors and large-artery atherosclerosis in the carotid territory were predictors of negative long-term outcome after the initial stroke.

CONCLUSIONS

The long-term prognosis for the ischemic stroke in the young is better than in the elderly, but the risk of mortality in young adults with ischemic stroke is much higher than in the general population of the same age. A bad prognosis is associated with an atherosclerotic risk profile, with a higher mortality and recurrent stroke rates and poorer functional recovery. The main functional limitation in the young survivors of their initial ischemic stroke occurs in work activity, since most patients are independent but almost half of them do not return to work.

From nearly tilted waves to cavity phase solitons in broad area lasers with squeezed vacuum

Phase domains and phase solitons in two-level amplifying media damped by a squeezed vacuum are predicted for the first time. Two different types of pattern formation are found depending on the relative value of the cavity detuning to the squeezed parameter: the usual one in lasers via a supercritical Hopf bifurcation and a new one via pitchfork bifurcation.

Cellular automaton model for the simulation of laser dynamics

The classical modeling approach for laser study relies on the differential equations. In this paper, a cellular automaton model is proposed as an alternative for the simulation of population dynamics. Even though the model is simplified it captures the essence of laser phenomenology: (i) there is a threshold pumping rate that depends inversely on the decaying lifetime of the atoms and the photons; and (ii) depending on these lifetimes and on the pumping rate, a constant or an oscillatory behavior can be observed. More complex behaviors such as spiking and pattern formation can also be studied with the cellular automaton model.

Isolated cervical lymphadenopathy as unique manifestation of Brucellosis

We report the case of a 42-y-old male with an isolated cervical lymphadenopathy due to Brucella melitensis. The diagnosis was established by isolation of B. melitensis in a lymphatic specimen obtained by fine-needle aspiration and confirmed by serological test results showing high levels of Brucella agglutinins. Mycobacteria-specific cultures were negative. Treatment with streptomycin and doxycycline resulted in complete healing. Exceptionally, and only if the epidemiologic context supports it, brucellosis should be considered in the differential diagnosis of lymphadenopathy.

Incidence of tuberculosis and the importance of treatment of latent tuberculosis infection in a Spanish prison population

OBJECTIVE

To establish the incidence of tuberculosis (TB) in a prison population and its link with latent tuberculosis infection treatment (LTIT).

METHODS

From 1991 to 1999 a TB programme was run in a Spanish prison. A cohort study was conducted to know TB incidence and the associated variables.

RESULTS

Of 1,050 people studied, 10% were co-infected by the human immunodeficiency virus (HIV) and Mycobacterium tuberculosis. Twenty-three cases of TB were detected, an incidence rate of 6.39 per 1,000 person-years of follow-up. Multivariate analysis showed HIV-infected patients (RR 4.07, 95%CI 2.61-6.35), and those infected by M. tuberculosis who did not undergo LTIT (RR 10.15, 95%CI 0.90-50.59) to be at greater risk of developing TB. In TST reactors, those co-infected with HIV (RR 10.15, 95%CI 3.80-27.07) and those who had not undergone LTIT (RR 8.53, 95%CI 1.12-64.86) were shown to be at the greatest risk of developing TB.

CONCLUSIONS

The observed incidence of TB is much higher in prisons than in the community at large. HIV-M. tuberculosis co-infection appears as the main risk factor for developing TB, while LTIT significantly reduces incidence.

Long term results of mechanical prostheses for treatment of active infective endocarditis

OBJECTIVE

To analyse the long term results of mechanical prostheses for treating active infective endocarditis.

DESIGN

Prospective cohort study of a consecutive series of patients diagnosed with infective endocarditis and operated on in the active phase of the infection for insertion of a mechanical prosthesis.

SETTING

Tertiary referral centre in a metropolitan area.

RESULTS

Between 1975 and 1997, 637 cases of infective endocarditis were diagnosed in the centre. Of these, 436 were left sided (with overall mortality of 20.3%). Surgical treatment in the active phase of the infection was needed in 141 patients (72% native, 28% prosthetic infective endocarditis). Mechanical prostheses were used in 131 patients. Operative mortality was 30.5% (40 patients). Ninety one survivors were followed up prospectively for (mean (SD)) 5.4 (4.5) years. Thirteen patients developed prosthetic valve dysfunction. Nine patients suffered reinfection: four of these (4%) were early and five were late. The median time from surgery for late reinfection was 1.4 years. During follow up, 12 patients died. Excluding operative mortality, actuarial survival was 86.6% at five years and 83.7% at 10 years; actuarial survival free from death, reoperation, and reinfection was 73.1% at five years and 59.8% at 10 years.

CONCLUSIONS

In patients surviving acute infective endocarditis and receiving mechanical prostheses, the rate of early reinfection compares well with reported results of homografts. In addition, prosthesis dysfunction rate is low and long term survival is good. These data should prove useful for comparison with long term studies, when available, using other types of valve surgery in active infective endocarditis.

Long term results of mechanical prostheses for treatment of active infective endocarditis

OBJECTIVE

To analyse the long term results of mechanical prostheses for treating active infective endocarditis.

DESIGN

Prospective cohort study of a consecutive series of patients diagnosed with infective endocarditis and operated on in the active phase of the infection for insertion of a mechanical prosthesis.

SETTING

Tertiary referral centre in a metropolitan area.

RESULTS

Between 1975 and 1997, 637 cases of infective endocarditis were diagnosed in the centre. Of these, 436 were left sided (with overall mortality of 20.3%). Surgical treatment in the active phase of the infection was needed in 141 patients (72% native, 28% prosthetic infective endocarditis). Mechanical prostheses were used in 131 patients. Operative mortality was 30.5% (40 patients). Ninety one survivors were followed up prospectively for (mean (SD)) 5.4 (4.5) years. Thirteen patients developed prosthetic valve dysfunction. Nine patients suffered reinfection: four of these (4%) were early and five were late. The median time from surgery for late reinfection was 1.4 years. During follow up, 12 patients died. Excluding operative mortality, actuarial survival was 86.6% at five years and 83.7% at 10 years; actuarial survival free from death, reoperation, and reinfection was 73.1% at five years and 59.8% at 10 years.

CONCLUSIONS

In patients surviving acute infective endocarditis and receiving mechanical prostheses, the rate of early reinfection compares well with reported results of homografts. In addition, prosthesis dysfunction rate is low and long term survival is good. These data should prove useful for comparison with long term studies, when available, using other types of valve surgery in active infective endocarditis.

Epiphrenic diverticula, esophageal carcinoma and esophagopleural fistula

A case report of a patient with two epiphrenic diverticula and a squamous cell carcinoma within one of them is presented. Moreover, a pleural empyema and an esophagopleural fistula appeared following the neoplasic diverticulum perforation. Only a few cases have been previously described in the English-language literature. An additional one is now presented.

Time course of sleep-related breathing disorders in first-ever stroke or transient ischemic attack

To investigate the prevalence and behavior of sleep-related breathing disorders (SRBDs) associated with a first-ever stroke or transient ischemic attack (TIA), we prospectively studied 161 consecutive patients admitted to our stroke unit. Complete neurological assessment was performed to determine parenchymatous and vascular localization of the neurological lesion. Stroke subtype was categorized as TIA, ischemic (IS), or hemorrhagic (HS). A portable respiratory recording (PRR) study was performed within 48-72 h after admission (acute phase), and subsequently after 3 mo (stable phase). During the acute phase, 116 patients (71.4%) had an apnea-hypopnea index (AHI) > 10 events/h and 45 (28%) had an AHI > 30. No relationships were found between sleep-related respiratory events and the topographical parenchymatous location of the neurological lesion or vascular involvement. Cheyne-Stokes breathing (CSB) was observed in 42 cases (26.1%). There were no significant differences in SRBD according to the stroke subtype except for the central apnea index (CAI). During the stable phase a second PRR was performed in 86 patients: 53 of 86 had an AHI > 10 and 17 of 86 had an AHI > 30. The AHI and CAI were significantly lower than those in the acute phase (16.9 +/- 13.8 versus 22.4 +/- 17.3 and 3.3 +/- 7.6 versus 6.2 +/- 10.2, respectively) (p < 0.05) while the obstructive apnea index (OAI) remained unchanged. CSB was observed in 6 of 86 patients. The prevalence of SRBD in patients with first-ever stroke or TIA is higher than expected from the available epidemiological data in our country. No correlation was found between neurological location and the presence or type of SRBD. Obstructive events seem to be a condition prior to the neurological disease whereas central events and CSB could be its consequence.

Time resolved pattern evolution in a large aperture laser

We have measured quasiinstantaneous transverse patterns in a broad aperture laser. Nonordered patterns yielding to boundary determined regular structures in progressive time-integrated recording are observed. The linear analysis and numerical integration of the full Maxwell-Bloch equations allow us to interpret the features of the experiment. We show that this system being far from threshold cannot be fully understood with a perturbative model.

[HIV infection in the health care are of Leon. Incidence from 1983-1997]

BACKGROUND

The aim of the present work was to know the incidence of HIV infection in the sanitary area of León, and its tendency, throughout the period 1983-1997.

MATERIAL AND METHODS

A register of cases with the patients attended in the area hospitals, those detected in the Penitentiary Centre of León and notifications of cases of AIDS at a national level have been used. Only the patients residing in a municipality belonging to the area at the time of detection of the infection have been included. Age, sex, risk group, year of detection of the infection, development to AIDS and mortality were analysed. The Spearman coefficient correlation range has been used for the study of tendency.

RESULTS

509 cases of HIV infection (374 males and 134 females) were detected in the area from 1983 to 1997. The accumulated incidence throughout the period of study was 1,368/million inhabitants. The annual incidence shows and upward phase until 1990, followed by another of plateau (1990-1993). In 1994-1995 there was a decrease, interrupted in 1996-1997. The curve as a whole doesn't reveal a descending tendency (p > 0.05). The annual incidence in the IDU follow a similar pattern to that of the complete group while the group of heterosexual transmission shows a tendency to increase (p < 0.025). 223 patients (43.8%) developed AIDS, 195 of whom we know the evolution. Of these, 139 have died and 56 are still alive.

CONCLUSIONS

There is no evidence that the incidence of HIV infection tends to decrease in the sanitary area of León at present. This is probably related to the behaviour of the two main risk groups: a tendency to stability in the case of IDU and to increase in heterosexual transmission. It is important to insist on the prevention campaigns, especially those directed towards avoiding heterosexual transmission.

Long-term storage at -80 degrees C of hematopoietic progenitor cells with 5-percent dimethyl sulfoxide as the sole cryoprotectant

BACKGROUND

Hematopoietic progenitor cells (HPCs) can be cryopreserved and stored below -120 degrees C in liquid nitrogen or at -80 degrees C in mechanical freezers.

STUDY DESIGN AND METHODS

The feasibility of long-term storage of HPCs at -80 degrees C was investigated. The studies included a comparison of 5- and 10-percent dimethyl sulfoxide (DMSO) as cryoprotectant at various lengths of storage time. Mononuclear cell (MNC) recovery and viability and colony-forming unit-granulocyte-macrophage (CFU-GM) and burst-forming unit-erythroid (BFU-E) recovery assays were performed. The peripheral blood HPCs of 24 consecutive patients included in the program of autologous transplantation were studied.

RESULTS

The MNC viability decreased progressively with the length of time from cryopreservation, reaching 32 percent after 31 months of storage. The recovery rates of CFU-GM and BFU-E also decreased progressively with the duration of frozen storage, to 50 and 43.5 percent, respectively, after 12 months and to 0 percent (both) after 24 months. At 6 months of storage, MNC viability was 80 percent, and CFU-GM and BFU-E recovery was 63.5 and 80.5 percent, respectively. There were no differences between MNCs cryopreserved with 5- or 10-percent DMSO in terms of cell viability. There were no differences between CFU-GM recovery or BFU-E recovery from HPCs cryopreserved in 5- or 10-percent DMSO. Patients given HPCs stored in these conditions for periods ranging between 123 and 202 days showed a complete and rapid hematologic recovery.

CONCLUSION

HPCs can be cryopreserved at -80 degrees C with 5-percent DMSO and stored at -80 degrees C no longer than 6 months. A 5-percent DMSO concentration is comparable to a with 10-percent concentration in terms of recovery and MNC viability.

Should patients with sleep apnoea/hypopnoea syndrome be diagnosed and managed on the basis of home sleep studies?

The purpose of this study was to analyse the validity and the economic efficiency of a portable monitor of respiratory parameters (PMRP), used in a home setting for the diagnosis of sleep apnoea/hypopnoea syndrome (SAHS). Eighty nine patients with suspected SAHS were studied in two settings: in the sleep laboratory using full-polysomnography (full-PSG); and at the patient's home using a PMRP. In the home setting, 50 patients were assisted by a technician and 39 set up the equipment themselves. SAHS (apnoea/hypopnoea index (AHI) >10 events x h(-1) by means of full-PSG) was diagnosed in 75 of the 89 patients. An acceptable agreement was obtained between the AHI measured by full-PSG and PMRP, according to the Bland and Altman method of concordance (mean bias 2.56; 95% confidence interval 3.25). Sensitivity and specificity of PMRP were adequate for diagnostic purposes; however, their values rely on the prior PMRP-AHI cut-off point selected with reference to full-PSG-AHI >10. The clinical therapeutic decision taken after PMRP agreed with that taken with full-PSG in 79 patients (89%). Although 10% of the studies with an individual set-up needed repetition, both of the domiciliary modalities (with and without a technician's intervention) were, economically, about three times more efficient than full-PSG. In conclusion, we believe that patients with a suspected sleep apnoea/hypopnoea syndrome should initially be studied in a home setting with a portable monitor of respiratory parameters, since it is a reliable method with an acceptable cost-effective profile.

Topographic measurements of precision-ground optical glasses

We studied the surfaces of six precision-ground optical glass samples of fused silica, BK-7, BaCD16, LaC14, NbF1, and LHG8 glass, using a mechanical profiler, a photon tunneling microscope, and a scanning force microscope. The measured roughnesses of the scanning force microscope varied from 3.5 A rms for BK-7 glass to 30 A rms for LHG8 laser glass. Good agreement was obtained among the roughness values measured with all three instruments.

Positioning of chest tubes: effects on pressure and drainage

BACKGROUND: Maintaining a chest drainage tube in a position that is free of dependent loops, as is commonly recommended, can be very difficult. Is there a beneficial effect on the patient's outcome when the drainage tubing is free of dependent loops? OBJECTIVE: The purpose of this study was to determine, under controlled laboratory conditions, (1) what are the differences in drainage with tubing in straight, coiled, or dependent-loop (with and without periodic lifting) positions and (2) what are the differences in pressure with each of the four tubing conditions? METHODS: In laboratory simulations, pressure and drainage were observed in a chest tube drainage system that was connected to a glass bottle simulating the lung. Pressure and drainage were measured for 1 hour with the drainage tubing placed in straight, coiled, and dependent-loop positions. For the periodic lifting condition, the dependent loop was lifted and drained every 15 minutes. RESULTS: We found no differences in pressure or drainage between straight and coiled positions of the drainage tubing. However, with the dependent-loop position, pressure at the "lung" side increased from about -18 cm H2O to as high as +8 cm H2O. Drainage dropped to zero without tube lifting. When the tube was lifted and drained every 15 minutes, there was no difference in drainage with the tubing in the straight or coiled positions. CONCLUSION: Findings support recommendations to maintain tubing free of dependent loops by placing tubing in straight or coiled positions. Frequently lifting and draining a dependent loop will provide the same total drainage amount as maintaining the tubing in a straight or coiled position, but pressures may be altered sufficiently within the tube to exceed recommended levels.

Positioning of chest tubes: effects on pressure and drainage

BACKGROUND

Maintaining a chest drainage tube in a position that is free of dependent loops, as is commonly recommended, can be very difficult. Is there a beneficial effect on the patient's outcome when the drainage tubing is free of dependent loops?

OBJECTIVE

The purpose of this study was to determine, under controlled laboratory conditions, (1) what are the differences in drainage with tubing in straight, coiled, or dependent-loop (with and without periodic lifting) positions and (2) what are the differences in pressure with each of the four tubing conditions?

METHODS

In laboratory simulations, pressure and drainage were observed in a chest tube drainage system that was connected to a glass bottle simulating the lung. Pressure and drainage were measured for 1 hour with the drainage tubing placed in straight, coiled, and dependent-loop positions. For the periodic lifting condition, the dependent loop was lifted and drained every 15 minutes.

RESULTS

We found no differences in pressure or drainage between straight and coiled positions of the drainage tubing. However, with the dependent-loop position, pressure at the "lung" side increased from about -18 cm H2O to as high as +8 cm H2O. Drainage dropped to zero without tube lifting. When the tube was lifted and drained every 15 minutes, there was no difference in drainage with the tubing in the straight or coiled positions.

CONCLUSION

Findings support recommendations to maintain tubing free of dependent loops by placing tubing in straight or coiled positions. Frequently lifting and draining a dependent loop will provide the same total drainage amount as maintaining the tubing in a straight or coiled position, but pressures may be altered sufficiently within the tube to exceed recommended levels.

Transverse pattern morphogenesis in a CO(2) laser

Irregular and nonrepetitive transverse intensity distributions were measured in the near field during the gain-switch pulse (60-ns width) of a transversely excited atmospheric CO(2) laser. Transverse patterns are regular and repetitive in the long-pulse (1-micros width) mode and in ensemble average in the short-pulse mode, and in both cases symmetry is imposed by the boundary conditions. Short-pulse transverse patterns formed by lasing domains appear with a mean size of 0.8 mm. The prediction of domain size based on a model of population inversion filamentation agrees with the experimental result.

Laser-threshold calculations for lasing of acidbase species in proton-transfer media

An estimate of laser thresholds for both the acid and the base species of dyes undergoing proton-transfer reactions is given. It is seen how the excited-state kinetic constants and proton concentration affect the laser threshold of each species. Calculations of laser threshold for simultaneous lasing of both species are also carried out. The latter is applied to the simultaneous lasing of neutral and acid forms of the 4-Amino-1,7-dimethylpyrido[2,3-c]-1,2,6-thiadiazine 2,2-dioxide in acetonitrile and corroborates the experimental results.

Pyrazino[2,3-c]-1,2,6-thiadiazine 2,2-dioxides: a new family of widely tunable, acid-base dye lasers

Laser emission of different acid-base species of pyrazino[2,3-c]-1,2,6-thiadiazine 2,2-dioxides has been observed. Lasing energy efficiency and spectral and temporal characteristics in dimethyl sulfoxide (DMSO) and acetonitrile, pumped with a N(2) laser (3.7 ns, 0.5 mJ/pulse) in two different two-mirror resonators, have been measured. A very wide tuning range (110 nm) has been determined in the most efficient species, and the triplet-state influence on the species' laser emission was investigated. No photochemical degradation was detected. The deprotonation observed in DMSO in previous spectroscopic measurements did not contribute measurably to laser emission.

Long-term partial liquid ventilation (PLV) with perflubron in the near-term baboon neonate

PURPOSE

The feasibility and safety of continuous long-term (4-5 day) partial liquid ventilation (PLV) using perflubron was demonstrated in newborn baboons. PLV, a potential therapy for adult and neonatal respiratory distress syndrome (RDS), is conventional mechanical ventilation (CMV) with the lung filled to about functional residual capacity with perfluorochemical liquid.

PROTOCOL

As a pilot trial for a larger preclinical study focused on the safety of extended duration PLV, three near term baboons were studied. The animals were delivered by cesarean section, anesthetized, intubated and placed on CMV. The animals were given intratracheal perflubron (30 ml/kg) and maintained on PLV for 96 hours. The transition back to gas ventilation occurred, after draining, over the fifth day (hrs 96-120).

RESULTS

Two of the animals were born with normal pulmonary function, while the third developed respiratory distress prior to PLV. All the animals were adequately supported with PLV using moderate ventilator settings and low concentrations of oxygen. Perflubron distribution was enhanced by periodic rotation of the animals. Preliminary histology show vacuolated alveolar macrophages and no evidence of edema or other significant changes in the lungs. Pulmonary function in the RDS animal, after PLV treatment, showed normal gas exchange and lung mechanics.

CONCLUSIONS

Three near term baboons, one with clinical RDS, tolerated 4 days of PLV followed by 1 day of CMV without complications using practical clinical management methods.

Photon Tunneling Microscopy of Polymeric Surfaces

With photon tunneling microscopy it is possible to image polymeric and other dielectric surfaces by means of the unusual properties of photon tunneling or evanescent waves. Vertical resolution is 1 nanometer, limited by the detector, over a vertical range of half a wavelength. Lateral resolution is better than a quarter of a wavelength over a field of view up to 125 micrometers. Samples can be surveyed in real time in air, with no need for metallization, and without shadowing or the intrusive effects of electrons or scanning probes. The use of this technique to study single crystals of polyethylene and processes such as latex film formation and the evolution of polystyrene topography while dewetting above the glass transition temperature are described.

Photon tunneling microscopy of diamond-turned surfaces

The photon tunneling microscope's high-resolution, large-field, and real-time three-dimensional display with profilometry and continuously variable perspective make it a powerful tool for analysis of diamond-turned surfaces.