[The expression of LINC00052 during glycidyl methacrylate-induced malignant transformation of 16HBE cells].

Objective: To investigate the expression and role of LINC00052 during glycidyl methacrylate (GMA) -induced malignant transformation of 16HBE cells. Methods: Human bronchial epithelial (16HBE) cells were divided into GMA transformation group and corresponding DMSO control group, and the 10th, 20th and 30th generation cells of each group were collected LncRNA microarrays were used to analysis expression of LINC00052 in different stage of malignant transformation. Bioinformatics analysis was applied and the relative expression of LINC00052 and its potentially target genes was detected by real-time quantification PCR (qPCR) . Results: The results of microarray analysis showed that LINC00052 was up-regulated by 1.32-fold, down-regulated by 1.64-fold and down-regulated by 4.92-fold in the malignant transformation early (P10) , middle term (P20) and late (P30) , respectively, The results of qPCR showed that compared with the DMSO control group, the expression of LINC00052 was up-regulated by 1.55 times, down-regulated by 1.20 times and down-regulated by 2.35 times in P10, P20 and P30, respectively, and the difference was statistically significant (P<0.05) . There was a statistically significant difference in the relative expression of NTRK3 between the GMA transformation group of P10 and P30 generations with the corresponding DMSO control group (P<0.05) . Conclusion: LINC00052 is highly expressed in early time of GMA-induced malignant transformation of 16HBE, and down-regulated in the middle and last stage of malignant transformation and may play a protective role in GMA-induced malignant transformation of 16HBE by influencing the expression of its target gene NTRK3.

Proliferation effects of cinnamon extract on human HeLa and HL-60 tumor cell lines.

OBJECTIVE: To investigate the possible anti-cancer properties of cinnamon extract on two human tumor cell lines, HeLa cells and HL-60 cells. MATERIALS AND METHODS: Two human tumor cell lines, HeLa cells and HL-60 cells, were exposed to increased concentrations of an extract prepared from cinnamon. The cell proliferation and cell cycle distribution were evaluated using MTT assay and flow cytometry, respectively. The possible action mechanism was also investigated by Western blot. RESULTS: The results showed that cinnamon extract strongly inhibited tumor cell proliferation in a dose-dependent manner and exhibited dramatic increases in the percentage of cells in G2/M in parallel with exposure to increasing concentration of cinnamon extract. The Western blot results showed that cinnamon extract reduced the cyclin A, cyclin B1, ERK2, and p-ERK proteins expression. CONCLUSIONS: Our study suggested that cinnamon extract inhibit the tumor cell survival by both down-regulated their target cell cycle regulation molecules and mitosis regulation molecules.

[Oxidative damage effects induced by CdTe quantum dots in mice].

Objective: To investigate Oxidative damage effects induced by CdTe Quantum Dots (QDs) in mice. Methods: 40 ICR mice were randomly divided into 5 groups: one control group (normal saline) ; four CdTe QDs (exposed by intravenous injection of 0.2 ml of CdTe QDs at the concentration of 0、0.5、5.0、50.0 and 500.0 nmol/ml respectively) . After 24 h, the mice were decapitated and the blood was collected for serum biochemically indexes、hematology indexes, the activities of SOD、GSH-Px and the concentration of MDA were all detected. Results: The results showed in the four CdTe QDs exposure groups, the level of CRE、PLT and the concentration of MDA were all significantly lower than those of the control group (P<0.05 or P<0.01) ; the activities GSH-Px in 50.0 and 500.0 nmol/ml CdTe QDs group were significantly higher than those of control group (P<0.01) . Conclusion: It was suggested that CdTe QDs at 0.5 nmol/ml could induce Oxidative damage effects in mice.

Echocardiographic follow-up study of the Ross procedure in older versus younger patients.

OBJECTIVES: This study was designed to determine echocardiographic follow-up results of the Ross procedure in older adult patients with aortic valve disease. BACKGROUND: The excellent long-term results of the Ross procedure from several institutions have indicated that the pulmonary autograft may be the best available substitute for the diseased aortic valve in children and adolescents. The advantages of this operation include optimal hemodynamics and elimination of thromboembolic complications. These features may benefit older adult patients as well. METHODS: We reviewed data from 49 consecutive patients who had a Ross procedure between 1991 and 1996. Preoperative and postoperative Doppler echocardiographic studies were available for 44 patients (22 men, 22 women; mean [+/-SD] age 36 +/- 14 years) who were grouped into <40 (n = 25) and > or =40 years old (n = 19). Measurements included left ventricular diastolic volume (LVDV), mass, and ejection fraction (EF); a peak pressure gradient across autograft in the aortic position and homograft in the pulmonary position; and valvular regurgitation. RESULTS: The mean length of echocardiographic follow-up was 36 +/- 16 months. Postoperatively, there was a reduction in LVDV and left ventricular mass in both age groups: 153 +/- 99 mL to 111 +/- 72 mL (P =.015) and 210 +/- 93 g to 152 +/- 54 g (P =.002) for younger patients, 174 +/- 115 mL to 126 +/- 43 mL (P =.17) and 233 +/- 71 g to 215 +/- 65 g (P =.19) for older patients. No significant change in EF was noted in the younger age group. However, in the older age group a significant decrease to EF <25% was found in 2 patients 1 year after surgery. Moderate autograft regurgitation was also detected in 2 patients: 1 in each age group. Pressure gradients across the autograft remained within the normal range in both age groups. Two younger patients had severe homograft stenosis with peak gradients of 100 and 62 mm Hg. The older patients did not demonstrate homograft dysfunction. CONCLUSIONS: The Ross procedure can be performed in selected older adults with aortic valve disease and provides durable valves in both aortic and pulmonic positions for at least 3 years after surgery but may result in less favorable left ventricular remodeling compared with that in the younger patients. Further follow-up will be necessary to determine the long-term outcome of the Ross procedure in this older adult patient population.

Diagnosis and surgical correction of cor triatriatum in an adult: combined use of transesophageal echocardiography and catheterization.

This is an unusual case of a 37-year-old male whose initial presentation to medical care was for dyspnea. A transthoracic echocardiogram was suspicious for cor triatriatum, which was confirmed by transesophageal echocardiography. Since the resting transmembrane gradient was low, a cardiac catheterization with exercise hemodynamics was performed and demonstrated a marked increase in pulmonary capillary wedge and pulmonary artery pressures. The cor triatriatum was successfully resected at surgery. We have reviewed the English literature and find this to be a unique approach to diagnosis and management.

Assessment of left ventricular diastolic function after single lung transplantation in patients with severe pulmonary hypertension.

OBJECTIVES: This study was designed to observe left ventricular filling by Doppler echocardiography before and after single lung transplantation in patients with severe pulmonary hypertension. BACKGROUND: Right ventricular pressure overload causes the deformation of the left ventricle by septal flattening toward its cavity, which may result in impaired left ventricular early filling. Recent studies have demonstrated the ability of single lung transplantation to restore right ventricular function in patients with severe pulmonary hypertension. However, changes in left ventricular filling after single lung transplantation have not been well studied. METHODS: We performed Doppler echocardiography in nine patients with severe pulmonary hypertension before, early (<3 months), and late (>1 year) after single lung transplantation. The study group consisted of eight female patients and one male patient with mean age of 32 years (range, 15 to 48 years). Six patients were diagnosed as having primary pulmonary hypertension and three as having secondary pulmonary hypertension. Nine age-matched normal subjects served as a control group. Doppler measurements included the following: transmitral flow early (E) and atrial (A) velocities, integrals (Ei and Ai), and left ventricular isovolumic relaxation time. The ratio of E/A and atrial filling fraction (Ai/Ei+Ai, AFF) were also determined. Left ventricular geometry was assessed from mid-short axis view with a circular shape factor (CSF). RESULTS: Early after lung transplantation, the left ventricular geometry became more circular with CSF (mean+/-SD) increasing from 0.63+/-0.09 to 0.88+/-0.05 (p<0.05). However, impaired early filling persisted in the patient group (E/A 0.7+/-0.1 vs preoperative 0.6+/-0.1, AFF 0.61+/-0.1 vs 0.64+/-0.1; both p=not significant). One year later, the left ventricular filling had returned to normal range with E/A 1.4+/-0.6 and AFF 0.35+/-0.1. CONCLUSIONS: This study observed that the impaired left ventricular early filling persisted shortly after single lung transplantation in patients with severe pulmonary hypertension, despite findings that left ventricular geometry was restored earlier after reversal of pulmonary hypertension. The abnormal filling pattern appeared to be resolved 1 year later. The findings suggest the impaired early filling may be caused by intrinsic left ventricular abnormalities other than ventricular interaction in these patients.

Production and characterization of monoclonal anti-idiotypic antibody exhibiting a catalytic activity similar to carboxypeptidase A.

A new approach for producing catalytic anti-idiotypic antibody was developed. A monoclonal anti-idiotypic antibody which was induced against carboxypeptidase A (CPA) showed the catalytic activity similar to the original antigen. The activity of the catalytic antibody was investigated. Rabbits were immunized by bovine pancreas carboxypeptidase A. The antiserum was purified and used as antigen to immunize BALB/c mice to induce monoclonal anti-idiotypic antibodies. Screened for enzymatic activities, the monoclonal antibody 32C3 showed esterase activity. The hydrolysis of hippuryl-DL-phenyllactic acid by McAb 32C3 followed the enzymatic kinetics. In our experimental system, Kcat value was 0.0123 min-1 and Km was 0.04M. The acceleration rate was 1750 times compared to the rate of self-hydrolysis of the substrate. This hydrolysis reaction can be competitively inhibited by hydrocinnamic acid. This method could be effective to obtain catalytic antibodies with the characters close to natural enzymes.

Left atrial function in congestive heart failure: assessment by transmitral and pulmonary vein Doppler.

The relation of transmitral flow patterns and pulmonary venous velocities was analyzed from 50 heart failure patients (28 men, 22 women; mean [+/- SD] age 61 +/- 9 years) with a left ventricular ejection fraction < 40%. Doppler echocardiography was performed in all patients. Transmitral flow measurements included early (E) and atrial (A) velocities and deceleration time of E wave (DT). Patients were assigned to two groups according to E/A ratio, DT, or both: 20 patients in the restrictive group, and 30 patients in the nonrestrictive group. Pulmonary venous flow was obtained by the transthoracic approach. Systolic (S), diastolic (D) and atrial reversal (Ar) velocities were measured. Of the study population, 13 patients had simultaneously determined pulmonary capillary wedge pressure (PCWP). The results showed a lower S (28 +/- 11 vs. 51 +/- 10 cm/sec, p < 0.01), a higher D (66 +/- 13 vs. 44 +/- 10 cm/sec, p < 0.01) and a smaller Ar (12 +/- 10 vs. 24 +/- 9 cm/sec, p < 0.01) in the restrictive group compared with those in nonrestrictive group. In the subgroup of patients undergoing invasive hemodynamic studies, there was no relationship between PCWP and atrial reversal velocity. However, a significant correlation was observed for pulmonary systolic (r = -0.70, p < 0.01) and diastolic (r = 0.76, p < 0.01) velocities to PCWP. These findings suggest a reduction in left atrial compliance and atrial systolic function and both play important roles in heart failure patients with the restrictive transmitral flow pattern.

Musculoskeletal pain in cardiac ultrasonographers: results of a random survey.

Myalgias and arthralgias are common among workers whose jobs require repetitive isometric maneuvers or malalignment of body position. However, few systematic studies have been performed to evaluate the frequency of these complaints among cardiac ultrasonographers. Therefore the purpose of this study was to determine the prevalence of musculoskeletal pain (MSP) among ultrasonographers and to identify risk factors related to their occurrence. Two hundred twenty ultrasonographers randomly chosen from a list of more than 1600 active members of the American Society of Echocardiography were mailed surveys consisting of 22 questions. Included were questions regarding height, age, years of experience, frequency and type of physical exercise, and job-related parameters such as a number of scans per day, scanning from right or left side of bed, number of hours, bed type, type of equipment, and manual or self-propelled machines. Respondents were asked whether they had had back, neck, or shoulder pain related to their profession and to describe treatment rendered and its effectiveness. One hundred thirteen (51%) of 220 ultrasonographers responded to the survey. Ninety (80%) of 113 respondents reported new pain that was not present before they began scanning, with 42 of this group (46%) requiring either physiotherapy (n = 17) or medication (n = 23). Treatment was believed to be helpful in 63% of cases. Factors found to have a positive relationship to MSP included ultrasonographer height less than 63 inches, performing 100 or more scans per month, average scan time of 25 minutes or more per patient, and use of manually propelled machines (each p < 0.05). Factors found to have no relationship to MSP included age, type of equipment, right or left scan position, physical conditioning, bed type, and time between patients. Musculoskeletal pain is prevalent among cardiac ultrasonographers, and may have specific work-related factors for its occurrence.

Massive air embolus to the left ventricle: diagnosis and monitoring by serial echocardiography.

Air embolization is an unusual but potentially dangerous complication in left heart catheterization. Microbubbles can be detected with two-dimensional echocardiography, which is often used for this purpose during open heart and bypass surgeries. Permanent neurologic sequelae and hemodynamic collapse can result from embolization of air bubbles to the cerebral and coronary circulations, respectively. Hyperbaric oxygen is the treatment of choice for cerebral air embolization. We present a 39-year-old man who had air embolization during left ventriculography in the form of a large pocket of "pooled" air. The patient was treated with conservative therapy successfully. Two-dimensional transthoracic echocardiography was used to document the presence of the air and follow its dissolution.

Relation of Doppler transmitral flow patterns to functional status in congestive heart failure.

We analyzed the relation of Doppler transmitral flow patterns and New York Heart Association (NYHA) classification in 60 consecutive patients with heart failure (44 men and 16 women; mean age 58 +/- 13 years) with left ventricular ejection fraction of < 40 percent. Of the study population, 40 patients with mild to moderate heart failure underwent symptom-limited exercise testing. The relation of transmitral flow pattern and exercise tolerance was also analyzed. Doppler echocardiography was performed in all patients. The patients were subdivided into nonrestrictive and restrictive groups according to the pattern. The univariate analysis showed a relation for left ventricular ejection fraction (p = 0.01 by analysis of variance testing) and transmitral flow pattern (p = 0.0003 by chi-squared test) with NYHA classification. When the multivariate regression analysis was performed, only the restrictive pattern by Doppler emerged as an independent determinant of the advanced NYHA class (p = 0.005). In mild to moderate congestive heart failure, patients with nonrestrictive pattern exercised significantly longer than those with the restrictive pattern by an average of 133 seconds (p = 0.003) despite comparable reductions in ejection fraction. Thus the restrictive transmitral flow pattern by Doppler is a noninvasive marker for severe symptoms and diminished exercise tolerance in heart failure patients.

The assessment of left ventricular filling dynamics using an online automatic border detection algorithm: comparison with cineventriculography.

An echocardiographic system has been developed that performs automatic endocardial border detection and instantaneously calculates and displays a waveform of left ventricular cavity area versus time. The purpose of this study was to compare measurements of left ventricular filling dynamics from automatic border detection echocardiography with similar measurements from cineventriculography. Thirty-three patients undergoing cardiac catheterization had automatic border detection echocardiography performed within 45 minutes of cineventriculography. Ten patients had normal catheterization findings and 23 had cardiac disease. The automatic border detection waveforms generated from two echocardiographic views were measured to determine the fraction of filling occurring during the early diastolic rapid filling phase and during the filling phase resulting from atrial contraction. Similar fractions were derived from curves generated from frame-by-frame measurements of cineangiographic volumes. Results were analyzed by correlating echocardiographic and cineventriculographic results, and by a limits of agreement analysis (limits of agreement were +/- 2 standard deviations of the mean difference between echocardiography and cineventriculography). There were significant correlations between echocardiography and cineventriculography for each of the parameters studied. The best results were obtained for the apical four-chamber view (rapid filling fraction r = 0.72, P < 0.0001, atrial filling fraction r = 0.56, P < 0.001). Differences in filling patterns between normal and abnormal patient groups detected by cineventriculography were also detected by automatic border detection echocardiography. However, broad limits of agreement were observed, that may limit the ability of the automatic border detection system to reliably predict cineventriculographic results in an individual patient. Automatic border detection echocardiography can provide information about left ventricular filling dynamics that is similar to that obtained from frame-by-frame analysis of cineventriculograms. However, the variability in the results may limit the application of the technique in individual patients.

Quantification of mitral regurgitant volume by the color Doppler proximal isovelocity surface area method: a clinical study.

In vitro studies have demonstrated that regurgitant flow rate can be estimated by the color Doppler "proximal isovelocity surface area" (PISA) method. By applying the PISA method and continuity principle, we developed a formula to calculate mitral regurgitant volume: 2 pi r2.VN.FVI/Vo, where r = distance from the first jet alias to mitral leaflets, VN = aliasing velocity, FVI = flow velocity integral or regurgitant jet, and Vo = peak velocity through the regurgitant orifice. Doppler echocardiography was performed in 20 patients with mitral regurgitation. The mitral regurgitant volume was estimated by PISA and compared to cine ventriculographic grading. The results showed an increase in regurgitant volume by PISA compared with increasing angiographic grades of mitral regurgitation: 19 +/- 0.6, 18 +/- 5, 25 +/- 12, and 44 +/- 4 ml for grades 1+ to 4+, respectively (r = 0.77). Thus a formula developed from PISA is able to identify patients with a severe grade of mitral regurgitation and to provide an alternate approach to the noninvasive quantitation of mitral regurgitation.

A simplified method for determining regurgitant fraction by Doppler echocardiography in patients with aortic regurgitation.

OBJECTIVES: This study attempted to develop and validate a simple method for calculating aortic regurgitant fraction by use of pulsed wave Doppler echocardiography. BACKGROUND: Although several investigators have been able to determine aortic regurgitant fraction by Doppler echocardiography, the methods used require accurate determination of the cross-sectional areas of intracardiac sites at which the volumetric flow is calculated. METHODS: Our concept was based on a constant relation that exists between the cross-sectional area of the left ventricular outflow tract and the mitral valve annulus in normal subjects. To verify this, we used Doppler echocardiography to measure the flow velocity integral of the left ventricular outflow tract and the mitral annulus in the apical view in 50 normal subjects (32 men, 18 women, mean age 34 years). RESULTS: Close correlation (r = 0.95) was observed between the flow velocity integral (FVI) of the outflow tract (OT) and that of the mitral annulus (MA): FVIMA/FVIOT = 0.77. Because mitral flow equals aortic flow in normal subjects, the ratio of the cross-sectional area of the mitral annulus to that of the outflow tract was 1/0.77. In patients with aortic regurgitation, the regurgitant fraction (RF) = (Aortic flow-Mitral flow)/Aortic flow = 1-Mitral flow/Aortic flow. Substituting 0.77 for the area component of flow, RF = 1-(1/0.77).(FVIMA/FVIOT). To evaluate the accuracy of this method, we compared the regurgitant fraction derived by Doppler echocardiography with that from catheterization findings in 20 patients with aortic regurgitation (an isolated lesion was found in 14). The regurgitant fraction by catheterization was the difference between total (angiographic) and forward (thermodilution) stroke volumes as a percent of total flow. Good correlation was observed between catheterization and Doppler regurgitant fraction (r = 0.88, SEE 9%, p < 0.01). CONCLUSIONS: Thus, regurgitant fraction can be estimated from Doppler echocardiography in patients with aortic regurgitation by a method that requires only measurements of the flow velocity integral from the mitral annulus and left ventricular outflow tract.

Prognostic value of Doppler transmitral flow patterns in patients with congestive heart failure.

OBJECTIVES: This study was designed to determine whether Doppler echocardiographic transmitral flow patterns can predict cardiac mortality in patients with congestive heart failure. BACKGROUND: Previous studies have indicated that Doppler transmitral flow patterns are related to New York Heart Association functional class and exercise capacity in patients with congestive heart failure. However, the prognostic significance of these flow patterns is not known. METHODS: We analyzed the relation of transmitral flow patterns and cardiac mortality in 100 consecutive patients (76 men, 24 women; mean [+/- SD] age 60 +/- 11 years) with congestive heart failure symptoms and left ventricular ejection fraction < 40%. At the time of entry into the study, functional class and ejection fraction by radionuclide angiography were determined, and Doppler echocardiography was performed in all patients. Transmitral flow was obtained from the apical four-chamber view at the mitral annulus level. Measurements included early (E) and atrial (A) filling velocities, E/A ratio and deceleration time of the E wave. The patients were assigned to two groups according to E/A ratio or deceleration time of transmitral flow patterns, or both: a non-restrictive group (42 patients) with E/A < or = 1 or E/A = 1 to 2 and deceleration time > 140 ms, and a restrictive group (58 patients) with E/A > or = 2 or E/A = 1 to 2 and deceleration time < or = 140 ms. RESULTS: Of 100 patients, 26 died during a mean follow-up period of 16 +/- 8 months. The cumulative cardiac mortality rate determined by the Kaplan-Meier method was 14% at 1 year and 35% at 2 years. Cox proportional hazards model analysis revealed that transmitral flow (restrictive vs. nonrestrictive, chi-square 6.99, p = 0.008), patient gender (female vs. male, chi-square 4.59, p = 0.03) and New York Heart Association functional class (IV vs. II, chi-square 3.95, p = 0.05) were significantly related to cardiac mortality in patients with congestive heart failure. Mortality rate in the restrictive group was markedly higher than that in the nonrestrictive group at 1 year (19% vs. 5%, respectively, p < 0.05) and at 2 years (51% vs. 5%, respectively, p < 0.01) by log-rank test. Relative risk for cardiac death was estimated as 4.1 at 1 year and 8.6 at 2 years in the restrictive group compared with the nonrestrictive group. CONCLUSIONS: In patients with congestive heart failure, a restrictive transmitral flow pattern, female gender and advanced functional class are predictive of higher cardiac mortality. The restrictive transmitral flow pattern by Doppler echocardiography is the single best clinical predictor for cardiac death in patients with congestive heart failure.

Comparison of gray-scale and B-color ultrasound images in evaluating left ventricular systolic function in coronary artery disease.

To confirm whether or not echocardiographic B-color images (temperature, magenta, rainbow) are superior to ordinary gray-scale images, 62 coronary artery disease (CAD) patients (42 men and 20 women) underwent gray-scale and B-color echocardiography and cineangiography within 24 hours. Left ventricular (LV) volume was derived from angiography using the single-plane area-length method and was derived from echocardiography using single-plane modified Simpson's formula. In predicting angiographic volume, the correlations between B-color images and angiography were similar to that between the gray-scale image and angiography. In evaluating LV ejection fraction, the correlation coefficients between B-color images and angiography (temperature r = 0.93, magenta r = 0.93, rainbow r = 0.92) were slightly higher than that between the gray-scale image and angiography (r = 0.85) (p less than 0.05). We conclude that B-color images yield estimates of LV volumes that are of similar accuracy to gray-scale images in patients with CAD.

Reduction of left ventricular preload by lower body negative pressure alters Doppler transmitral filling patterns.

The objective of this study was to evaluate the effect of alterations in preload induced by lower body negative pressure on Doppler transmitral filling patterns. Echocardiograms and Doppler recordings were performed in 18 normal young men (aged 23 to 32 years) during various levels of lower body negative pressure (0, -20 and -50 mm Hg). Lower body negative pressure induced a reduction in diastolic velocity integral (from 12.17 +/- 0.79 to 8.42 +/- 0.71 cm, p = 0.0067) and consequently left ventricular diastolic diameter (from 5.11 +/- 0.09 to 4.45 +/- 0.1 cm, p less than 0.0001). There was a significant reflex increase in heart rate from 59.9 +/- 1.9 to 77.1 +/- 2.4 beats/min (p less than 0.0001), but blood pressure was unchanged. This reduction in preload altered Doppler transmittral filling patterns as follows: 1) peak early velocity (E) decreased from 59.2 +/- 3.8 to 39.1 +/- 1.7 cm/s (p less than 0.0001); 2) atrial filing velocity (A) was unchanged (35.58 +/- 1.5 to 33.52 +/- 1.4 cm/s, p = 0.517); 3) E/A ratio decreased from 1.7 +/- 0.13 to 1.19 +/- 0.08 (p = 0.0087); 4) mean acceleration (from 482 +/- 37 to 390 +/- 27 cm/s2, p = 0.03) and mean deceleration (from 327 +/- 31 to 169 +/- 21 cm/s2, p less than 0.001) of the early filling wave were significantly reduced; and 5) peak acceleration (from 907 +/- 42 to 829 +/- 29 cm/s2) and peak deceleration (from 771 +/- 94 to 547 +/- 76 cm/s2) also decreased, but not significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Control of recurrent inhibition of the lateral geniculate nucleus by afferents from the superior colliculus of the rabbit: a possible mechanism of saccadic suppression.

Stimulation of the ipsilateral superior colliculus elicited a short burst of discharges of the recurrent inhibitory interneurones in the geniculocortical pathway of the rabbit. The most effective stimulating sites for this excitation were located in the deep layers rather than the superficial layers of the superior colliculus. The short latency of the response (2.3 +/- 0.6 ms) implied an oligo-synaptic excitatory pathway from the deep layers of the superior colliculus to the recurrent interneurones located in the caudal reticular nucleus of the thalamus. Following the excitation of the interneurone, there was a prolonged inhibition which started 10-30 ms and ended 150 ms after the collicular stimulation. The maximal inhibition occurred 50-70 ms after the stimulation. The effects of collicular stimulation on the recurrent inhibitory interneurones may be concerned with the inhibition of the visual pathway during saccades and with the disinhibition of "facilitation" during fixation of a new visual target.