P594Contrast transthoracic echocardiography as a gatekeeper for patent foramen ovale closure.

BACKGROUND.: The presence of patent foramen ovale (PFO) has been linked to many illness, including cryptogenic stroke, transient ischemic attack, migraine, platypnea-orthodeoxia syndrome and decompression sickness in scuba divers. Transesophageal echocardiography is the gold standard technique for the visualization of atrial septal anatomy, but it is a secondary level exam, not always available, with additional associated costs and not completely free from procedural risks. Standard transthoracic echocardiography (TTE) has a too low sensitivity for PFO screening. PURPOSE.: The aim of the study was to assess the role of TTE associated with agitated saline contrast injection (contrast-TTE) as a gatekeeper for the identification of PFO in a large cohort of patients undergoing selection for percutaneous closure. METHODS.: A total of 200 patients undergoing a diagnostic work-up for the identification of PFO was imaged by contrast-TTE at rest and after provocative maneuvers (PM: Valsalva in all cases). Contrast TTE was graded from 0 to 4 on the bases of bubbles counting (0: no bubbles; 1: < 10 bubbles; 2: 10-30 bubbles; 3: >30 bubbles; 4: complete LV opacification). PFO closure was performed after a consensual clinical decision by the cardiologist and the neurologist taking into account comprehensive imaging, clinical evaluation and thrombophilia screening. PFO closure was always monitored by intracardiac echocardiography. RESULTS.: At baseline contrast TTE was positive (≥2) in 34 patients (17%) while contrast TTE with PM was positive in 94 cases (47%). 27 out of 200 patients (14%) had an interatrial septal aneurysms. PFO closure was performed in 34 cases (17%). All of these had severe right-to-left shunting (≥3) at contrast TTE and 9 cases had also an interatrial septal aneurysms. The procedure was aborted in only 1 patient due to a complex defect anatomy. CONCLUSION.: Contrast TTE with PM may be not only considered an accurate tool for the detection of PFO but may be also inserted in the diagnostic work- up as a primary gatekeeper for percutaneous closure. Severe shunting at contrast TTE influences final decision making in a large cohort of cases undergoing screening for PFO closure.

Linfoma de células en anillo de sello que simula carcinoma mucosecretante / Signet ring cell lymphoma mimicking mucin-producing carcinoma

Signet ring cell lymphoma is a rare neoplasm characterized by large, vacuolated and clear cells mimicking mucin-producing adenocarcinoma. It is localized in nodal and extranodal sites. A case of a 59 years old male, with a diffuse lymphoma signet ring cell type localized on oropharyngeal mucosa is reported. The histopathology study showed signet ring cells and the immunophenotype was: vimentine(+), CD45(+), CD20(+), Ig M(+), Kappa chain(+) and high index proliferative activity of neoplastic cells (Ki 67:70%). After a review of the literature and previous reports, we could not find a similar case in this anatomic site. The patient had a unfavourable clinical course and died two months after the diagnosis without receiving any treatment.

El linfoma de células en anillo de sello es una neoplasia poco frecuente, caracterizada por la presensenciade grandes células de citoplasma vacuolado, claro, similar a los encontrados en adenocarcinomasmucosecretantes. Se ha descripto en ganglios linfáticos y tejidos extralinfáticos. Se presenta el casode un paciente varón de 59 años con linfoma de células en anillo de sello localizado en pared lateral de orofaringe.Esta localización creemos que no ha sido descripta anteriormente. La histología mostró células en anillo de sello y el inmunofenotipo tumoral fue: vimentina, CD45, CD20, Ig M y cadenas kappa positivos, siendo la fracción de crecimiento tumoral alta (Ki 67:70%). El paciente evolucionó desfavorablemente y falleció a los dosmeses del diagnóstico sin recibir tratamiento.

Linfoma de células en anillo de sello que simula carcinoma mucosecretante / Signet ring cell lymphoma mimicking mucin-producing carcinoma

Signet ring cell lymphoma is a rare neoplasm characterized by large, vacuolated and clear cells mimicking mucin-producing adenocarcinoma. It is localized in nodal and extranodal sites. A case of a 59 years old male, with a diffuse lymphoma signet ring cell type localized on oropharyngeal mucosa is reported. The histopathology study showed signet ring cells and the immunophenotype was: vimentine(+), CD45(+), CD20(+), Ig M(+), Kappa chain(+) and high index proliferative activity of neoplastic cells (Ki 67:70%). After a review of the literature and previous reports, we could not find a similar case in this anatomic site. The patient had a unfavourable clinical course and died two months after the diagnosis without receiving any treatment.(AU)

El linfoma de células en anillo de sello es una neoplasia poco frecuente, caracterizada por la presensenciade grandes células de citoplasma vacuolado, claro, similar a los encontrados en adenocarcinomasmucosecretantes. Se ha descripto en ganglios linfáticos y tejidos extralinfáticos. Se presenta el casode un paciente varón de 59 años con linfoma de células en anillo de sello localizado en pared lateral de orofaringe.Esta localización creemos que no ha sido descripta anteriormente. La histología mostró células en anillo de sello y el inmunofenotipo tumoral fue: vimentina, CD45, CD20, Ig M y cadenas kappa positivos, siendo la fracción de crecimiento tumoral alta (Ki 67:70%). El paciente evolucionó desfavorablemente y falleció a los dosmeses del diagnóstico sin recibir tratamiento.(AU)

How the left and right sides of the heart, as well as pulmonary venous drainage, adapt to an increasing degree of head-up tilting in hypertrophic cardiomyopathy: differences from the normal heart.

OBJECTIVES: We aimed to assess the differences in the adaptive response of patients with hypertrophic cardiomyopathy (HCM) compared with normal subjects, as well as any association with increased susceptibility to the test. BACKGROUND: Diastolic function contributes importantly in the adaptation of the normal heart to head-up tilting. This mechanism may be disturbed by an impaired relaxation in HCM. METHODS: Twenty-one male patients with HCM (46 +/- 6 years old) and 22 healthy men (44 +/- 8 years) were studied using Doppler echocardiography after 1 and 10 min of head-up tilting at 20 degrees, 40 degrees and 60 degrees. RESULTS: In control subjects, tilting was associated with 1) a predominance of diastolic pulmonary venous flow and early left ventricular (LV) filling (atrium functioning as an open conduit); 2) right ventricular (RV) shrinkage; and 3) no LV dimensional variations. In patients with HCM, tilting was associated with 1) a prevalence of systolic pulmonary venous flow (atrium functioning as a reservoir in which filling depends on atrial relaxation and compliance) and late diastolic transmitral flow (atrium working as a booster pump); 2) LV shrinkage; and 3) no RV dimension variations. These mechanisms did not prevent stroke volume (SV) from decreasing at 40 degrees and 60 degrees in both groups. Because of a lower increase in heart rate (HR), a reduction in cardiac output (CO) was greater in patients with HCM. The responses were similar after 1 and 10 min of tilting in control subjects, whereas in patients, blood pressure (BP), SV and LV dimension fell more after 10 min. CONCLUSIONS: Adaptation of the normal heart to tilting is based on a ventricular interaction and LV diastolic properties; HCM relies on left atrial diastolic and systolic functions. An inadequate HR reaction to a fall in BP and SV in HCM (depressed reflexogenic activity) contributes to making CO more vulnerable by greater and more prolonged displacements.

Type II aortic dissection complicating discrete subvalvular aortic stenosis in an adult man.

We report a case of a 41-year-old man in whom discrete subaortic stenosis was complicated by a type II aortic dissection. Such an association has not been previously described. Diagnosis was readily achieved with echocardiography and an emergency repair was successful.

Antihypertensive efficacy of angiotensin converting enzyme inhibition and aspirin counteraction.

OBJECTIVE: Blockade of bradykinin breakdown and enhancement of prostaglandin release probably participate in the antihypertensive activity of angiotensin converting enzyme (ACE) inhibitors. Cyclooxygenase blockers may attenuate the efficacy of ACE inhibitors by interfering with prostaglandin synthesis, and patients taking aspirin may not benefit from ACE inhibition. This study was designed to evaluate the incidence of the counteractive phenomenon and to define minimal aspirin dosage that causes an antagonistic effect. METHODS: These were 26 patients with mild to moderate hypertension (group 1) and 26 patients with severe untreated primary hypertension (group 2). Enalapril (20 mg twice a day) was used as a single drug in group 1 and was added to the combination of long-acting nifedipine (30 mg/day) and atenolol (50 mg/day) in group 2. Aspirin was tested at doses of 100 and 300 mg/day, and an attenuation of more than 20% of the mean blood pressure decrease produced by enalapril was the criteria that defined antagonism. RESULTS: The 100 mg dose was ineffective. However, 300 mg aspirin had an antagonistic effect in 57% of patients in group 1 and 50% of patients in group 2: mean arterial pressure was lowered by 63% and 91% less, respectively. Results were independent of the drug administration order. In "responders," aspirin significantly attenuated the renin rise associated with ACE inhibition. CONCLUSIONS: These findings suggest that a number of ACE-inhibited patients are susceptible to 300 mg/day aspirin, regardless of hypertension severity. Antagonism may be mediated through prostaglandin inhibition according to predominance, in an individual patient, of prostaglandin activation (also as a renin secretory stimulus) or angiotensin blockade by enalapril.

[The antagonistic effect of aspirin on the expression of prostaglandin participation in the antihypertensive activity of ACE inhibitors]. / Effetto controattivo dell'aspirina quale espressione della partecipazione prostaglandinica all'attività antipertensiva dell'ACE-inibizione.

ACE-inhibitors antagonize both angiotensin production and bradykinin breakdown, resulting in enhancement of vasodilating prostaglandin release. This provides an explanation for the experimental observation that cycloxygenase blockers (such as aspirin or indomethacin) may counteract the antihypertensive efficacy of the ACE-inhibitors; it may be also possible that hypertensive patients taking aspirin as an antiplatelet agent may fail to benefit from ACE-inhibition. This study was aimed at: evaluating the magnitude and incidence of the inhibitory phenomenon; defining the minimal aspirin dosage that produces an antagonistic effect, as well as the possible reasons for a different individual susceptibility. We have studied untreated patients with mild (10 cases, Group 1), moderate (16 cases, Group 2) or severe (26 cases, Group 3) hypertension. The ACE-inhibitor enalapril was used at doses of 10 mg bid (groups 1 and 2) or 20 mg bid (Group 3). Active drug treatment periods had a 5-day duration. A daily dose of aspirin of 100 mg had no effect on the antihypertensive efficacy of enalapril. On the contrary, when a dose of 300 mg was used, 60, 57 and 50% of patients in Group 1, 2 and 3, respectively, showed a > 20% restraint of the mean arterial pressure fall with enalapril (20% was the lower arbitrary limit for defining antagonism). Inhibition was independent of the sequence of drug administration. In these patients counteraction averaged 60, 70 and 90%, respectively. In them, and not in the remaining patients in each group, aspirin substantially attenuated the renin rise elicited by ACE-inhibition. These data suggest that: a dosage of 100 mg aspirin is devoid of any inhibitory effect; more that 50% of ACE inhibited patients are, at least in the short term, susceptible to the action of 300 mg aspirin, regardless of the severity of hypertension; counteraction is seemingly mediated through a prostaglandin inhibition and depends on the individual predominance of prostaglandin activation (also as a renin secretory stimulus) or angiotensin inhibition by the ACE-inhibitor.

How the two sides of the heart adapt to graded impedance to venous return with head-up tilting.

OBJECTIVES: The study sought to probe whether the adaptation of the right ventricle to reduced preload may influence that of the left ventricle (interdependence) and whether and how this mechanism contributes to maintain an adequate pump function. BACKGROUND: A study like this requires that subjects be normal, restraint of venous return be gradual, systolic function and diastolic filling and dimensions of either ventricle be monitored. METHODS: Of 30 healthy men (mean [+/- SD] age 35 +/- 7 years) studied with Doppler echocardiography, 20 were studied in the supine position and after 20 degrees, 40 degrees and 60 degrees tilting for 10 min; the remaining 10 subjects were also studied at the same levels of tilting for 45 min. RESULTS: At 20 degrees, heart rate, blood pressure and stroke volume were steady; the diastolic right ventricular area was reduced (p < 0.001); and the end-diastolic dimension of the left ventricle did not vary. Tilting at 40 degrees and 60 degrees increased heart rate and diastolic pressure, decreased systolic pressure and stroke volume and reduced the diastolic dimensions of both ventricles. At any tilting level, right and left peak early inflow velocities (E) were decreased, peak late velocities (A) were unchanged, and E/A ratios were reduced, suggesting that the atrial-ventricular pressure difference was diminished bilaterally and that the atrial contribution to ventricular filling was maintained. Tachycardia at 40 degrees and 60 degrees tilting was not associated with enhancement of left ventricular fiber fractional shortening or mean velocity of shortening for any corresponding end-systolic wall stress; changes in heart rate also did not correlate with those in fiber fractional shortening and velocity of shortening. The adaptive responses to the same degrees of tilting for a duration of 45 min were comparable to those at 10 min. CONCLUSIONS: With moderate restraint of venous return, the left ventricle maintains filling and output in response to a reduction in right ventricular diastolic volume, which increases left ventricular compliance (interdependence), and to the pulmonary blood reservoir, which compensates for an immediate decrease in right ventricular stroke volume. The decreased lung blood volume would facilitate right ventricular ejection, resulting in a normal stroke output despite the reduced preload. Thus, mechanical adjustments fully compensate for moderate reduction of venous return. A more severe reduction requires chronotropic support for the maintenance of cardiac output. With prolongation of tilting time to 45 min, adaptive mechanisms do not become exhausted in normal persons.

Pericardial effusion after cardiac surgery: incidence, site, size, and haemodynamic consequences.

OBJECTIVE: To evaluate the incidence, characteristics, and haemodynamic consequences of pericardial effusion after cardiac surgery. DESIGN: Clinical, echocardiographic, and Doppler evaluations before and 8 days after cardiac surgery; with echocardiographic and Doppler follow up of patients with moderate or large pericardial effusion after operation. SETTING: Patients undergoing cardiac surgery at a tertiary centre. PATIENTS: 803 consecutive patients who had coronary artery bypass grafting (430), valve replacement (330), and other types of surgery (43). 23 were excluded because of early reoperation. MAIN OUTCOME MEASURES: Size and site of pericardial effusion evaluated by cross sectional echocardiography and signs of cardiac tamponade detected by ultrasound (right atrial and ventricular diastolic collapse, left ventricular diastolic collapse, distension of the inferior vena cava), and Doppler echocardiography (inspiratory decrease of aortic and mitral flow velocities). RESULTS: Pericardial effusion was detected in 498 (64%) of 780 patients and was more often associated with coronary artery bypass grafting than with valve replacement or other types of surgery; it was small in 68.4%, moderate in 29.8%, and large in 1.6%. Loculated effusions (57.8%) were more frequent than diffuse ones (42.2%). The size and site of effusion were related to the type of surgery. None of the small pericardial effusions increased in size; the amount of fluid decreased within a month in most patients with moderate effusion and in a few (7 patients) developed into a large effusion and cardiac tamponade. 15 individuals (1.9%) had cardiac tamponade; this event was significantly more common after valve replacement (12 patients) than after coronary artery bypass grafting (2 patients) or other types of surgery (1 patient after pulmonary embolectomy). In patients with cardiac tamponade aortic and mitral flow velocities invariably decreased during inspiration; the echocardiographic signs were less reliable. CONCLUSIONS: Pericardial effusion after cardiac surgery is common and its size and site are related to the type of surgery. Cardiac tamponade is rare and is more common in patients receiving oral anticoagulants. Echo-Doppler imaging is useful for the evaluation of pericardial fluid accumulations after cardiac surgery. It can identify effusions that herald cardiac tamponade.

[Multiplane transesophageal echocardiography for the monitoring of cardiac surgery]. / L'ecocardiografia transesofagea multiplana per il monitoraggio di interventi di cardiochirurgia.

Multiplane transesophageal echocardiography (TEE) allows visualization of the heart and great vessels through an infinite number of imaging planes and improves the diagnostic capabilities of mono and biplane TEE. This study was undertaken to test whether MTEE is a useful intraoperative monitoring method during cardiac surgery. Intraoperative multiplane TEE was performed in 200 patients (mean age 56 +/- 19 years) as a part of the routine clinical care. We systematically acquired cardiac images from the gastric fundus (short and long axes of the ventricles), lower esophagus (four-chamber, two-chamber, and long axis), upper esophagus (13 views concerning the aorta, pulmonary artery, left and right atrium, systemic and pulmonary veins, coronary arteries, right ventricular outflow tract), and searched for complete views of the thoracic descending aorta. All views analyzed in the preoperative (immediately before cardiopulmonary bypass), intraoperative and postoperative phases evaluating: the angle between current and 0 degree at which each view was obtained; the success rate of each view; the usefulness of the different views in providing essential additional clinical information compared to 0 degrees and 90 degrees of the traditional biplane TEE. Most views of the heart and great vessels were visualized in oblique planes, and other views were significantly improved thanks to slight angle corrections. Multiplane TEE was particularly useful in the preoperative and postoperative phases of aortic dissection (11 cases), mitral valve repair (13 cases), left ventricular aneurysmectomy (9 cases), right atrial thrombosis (1 case), positioning of left ventricular hemopump (2 cases), mitral-aortic endocarditis (3 cases), bleeding from proximal suture of an aortic heterograft (1 case).(ABSTRACT TRUNCATED AT 250 WORDS)

Sustained cardiac diastolic changes elicited by ultrafiltration in patients with moderate congestive heart failure: pathophysiological correlates.

OBJECTIVE: To investigate the pathophysiological (cardiac function and physical performance) significance of clinically silent interstitial lung water accumulation in patients with moderate heart failure; to use isolated ultrafiltration as a means of extravascular fluid reabsorption. DESIGN: Echocardiographic, Doppler, chest x-ray evaluations, and cardiopulmonary tests at baseline, soon after ultrafiltration (veno venous extracorporeal circuit), and four days, one month, and three months later. SETTING: University institute of cardiology. SUBJECTS: 24 patients with heart failure due to idiopathic dilated cardiomyopathy or ischaemic myocardial disease with sinus rhythm and ejection fraction less than 35%. Twelve were randomised to ultrafiltration and 12 were taken as controls. MAIN OUTCOME MEASURES: Left ventricular systolic function (from ultrasonography); Doppler evaluation of mitral, tricuspid, and aortic flow and echo-Doppler determination of cardiac output; radiological score of extravascular lung water; right and left ventricular filling pressures; oxygen consumption at peak exercise and exercise tolerance time in cardiopulmonary tests. RESULTS: Soon after ultrafiltration (1976 (760) ml of fluid removed) the following was observed: a reduction in radiological score of extravascular lung water (from 15(1) to 9(1)) and of right (from 7.1 (2.3) to 2.3 (1.7) mm Hg) and left (from 17.6 (8.8) to 9.5 (6.4) mm Hg) ventricular filling pressures; an increase in oxygen consumption at peak exercise (from 15.8 (3.3) to 17.6 (2) ml/min/kg) and of tolerance time (from 444 (138) to 508 (134) s); a slight decrease in atrial and ventricular dimensions; no changes in the systolic function of the left ventricle; a reduction of the early to late filling ratio in both ventricles (mitral valve from 2 (2) to 1.1 (1.1)); (tricuspid valve from 1.3 (1.3) to 0.69 (0.18)) and an increase in the deceleration time of mitral and tricuspid flow, reflecting a redistribution of filling to late diastole. Variations in the ventricular filling pattern, lung water content, and functional performance persisted for three months in all cases. None of these changes was detected in the control group. CONCLUSIONS: Reduction of interstitial lung water was probably the mechanism whereby ultrafiltration modified the pattern of filling of the two ventricles and improved functional performance.

[Tumor growth fraction and its relationship with morphology of transitional carcinoma of the bladder]. / Estudio de la fracción de crecimiento tumoral y su relación con la morfología en el carcinoma transicional de vejiga.

Papillary transitional cell carcinoma of the bladder (PTCCB) is characterized by a high recurrence rate with infiltration of bladder wall and surrounding tissues. The outcome is poor in 10-20% of the cases and these cannot be detected by conventional methods. Different methods have been utilized to identify this high risk patient group, such as the tumor growth factor (TGF). This is obtained with the KI-67 antibody, which identifies a nuclear protein in the cells in the active cellular cycle (G1, G2, S and mitosis). TGF represents the percentage of KI-67 positive tumor cells. The aims of the present study were: 1) to determine the correlation of the histological features and TGF in PTCCB; 2) to determine the percentage, if any, of superficial low grade lesions with a high TGF. Thirty-one transurethral biopsies of patients with PTCCB were analyzed to determine the histological grade (following the criteria described by Ash), wall infiltration (according to the IUAC criteria) and TGF (using the PAP technique). The study revealed 16 (52%) were low grade and 15 (48%) were high grade tumors, 20 (64.5%) were superficial (PTa-PT1), 9 (29%) were deep (PT1-PT4) and the degree of wall infiltration could not be determined in two cases. Of the 20 superficial tumors, 15 (75%) had a low (0-15%) and 5 (25%) had a high (> or = 16%) TGF. The 9 cases with deep infiltration of the bladder wall (PT2-PT4) had a high TGF.(ABSTRACT TRUNCATED AT 250 WORDS)

Mast cells in female mouse lymph nodes.

This study was designed to examine the possible role of sex steroid hormones on mast cells localized in uterus draining lymph nodes (UDLN) in mice. Young virgin estrous animals had more mast cells than diestrous animals in both the UDLN and popliteal lymph nodes (PLN). In retired breeders there were no differences in mast cell numbers of estrous and diestrous animals. There were no differences in mast cell numbers among weanling and older animals in diestrous in the UDLN but, in the PLN, mature animals in either diestrous or estrous had more mast cells than the PLN of weanlings. In mature animals, ovariectomy did not alter mast cell number in either node. However, ovariectomy of weanlings increased mast cell numbers in the PLN but not in the UDLN. These results suggest that the UDLN behaves as a nonclassical target organ for the endocrine system, with mast cell number variations related to gonadal steroid levels.

[Specific prostatic antigen in prostatic carcinoma: its relationship with tumor differentiation and clinical course]. / Antígeno prostático específico en el carcinoma de próstata: su relación con la diferenciación tumoral y la evolución clínica.

Carcinoma of the prostate is a tumor with a variable clinical course and a high incidence of local progression and/or metastasis. This study was undertaken to evaluate tissue prostate specific antigen (PSA) in patients with carcinoma of the prostate, its correlation with Gleason's grading and its value in predicting the clinical course of these patients. We studied 28 transurethral biopsies of patients with prostatic carcinoma utilizing HE and peroxidase-antiperoxidase staining techniques. These were given a score of 2 to 10 using Gleason's grading. PSA was determined according to percent positivity. The clinical course was considered favourable (F) when the lesion remained stable and unfavourable (U) when peri-prostatic spread was evidenced, metastasis and/or death from the disease. Statistical analysis was performed with the linear discriminatory test. PSA percentages ranged from 0 to 95 and the Gleason score from 3 to 11. There was an indirect correlation between these methods (r = 0.74): high Gleason scores corresponded to low PSA values and viceversa. PSA was highly positive in patients with F and U clinical courses whereas low positive values (less than 40%) were observed only in patients with U clinical course. High Gleason (8 to 10) and low (less than 5) scores were observed only in patients with a clinical course of U or F, respectively, while intermediate values (5 to 8) were not predictive of the clinical course. Discriminatory analysis gave Z values of -2.446 (P = 0.014) for PSA, -2.90 (P = 0.004) for the Gleason score in predicting prognosis, conferring a greater value overall to the latter.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoglobulins in human serum reactive with murine Friend leukaemia virus.

Fresh human sera neutralize Friend leukaemia virus (FLV). The activity is abolished by heating (56 degrees C for 30 min), hydrazine and EDTA treatment, suggesting the involvement of complement. Human sera also contain antibody which specifically reacts with FLV. Following incubation with human whole serum, IgG and F(ab')2 fragments, FLV acquire the ability to bind anti-human Ig sera, as shown in neutralization and radioimmunoprecipitation assay. The same is true for FLV-infected cells but not for uninfected control cells, as assessed by immunofluorescence. The binding of antibody to FLV-infected cells is prevented by pre-treating the cells with antisera to FLV and FLV-gp71, and is completed by FLV, FLV-gp71 and, to a lesser extent, by FLV-p12 and p30.

[Cellular hypersensitivity in the infection of mice by Junin virus. III. Experience with Cr51 an antitheta serum]. / Estudios de hipersensibilidad celular en la infección del raton por virus Junin. II. Experiencias con Cr51 y suero antitheta.

Several aspects of the appearance and development of delayed hypersensitivity in mice infected with Junin virus are described. The results obtained showed that the development of the immunological mechanisms occurs irrespective of age. Spleen cells of donor mice inoculated with one i.p. dose of Junin virus had a poor cytotoxic activity, as demonstrated by 51Cr release and adoptive immunity procedures. Spleen cells treated with anti-theta serum and complement did not strikingly affect the development of Junin virus disease in mice. This demonstrated the capacity of T lymphocytes to influence the course of the viral infection of newborn mice adoptively transferred with immune spleen cells. No difference were detected in the virus titer in the brains of transferred and control animals, this fact suggests that immune T lymphocytes are not involved in Junín virus clearance.