Contact screening in tuberculous pediatric patients.
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Child↗
Biomedical subjects
C Casanova
Publications and source records attributed to C Casanova.
Comparison of the responses to moving texture patterns of simple and complex cells in the cat's area 17.
1. Whether complex (C) cells are the only truly texture-sensitive units in the cat's primary visual cortex remains controversial. In view of the strong physiological significance of having putatively only one class of cells sensitive to visual noise in the striate cortex, we reinvestigated this issue. Sensitivities of simple (S) and C cells to noise were quantitatively studied and compared in order to clearly document the response properties of cells in the striate cortex to visual noise and to establish whether one can unequivocally segregate S from C cells on the basis of those specific properties. 2. Receptive fields were stimulated with all relevant stimuli, i.e., drifting sine-wave gratings, electronically generated noise pattern of 256 x 256 elements (ratio 1:1 of dark and light elements), and flashing and moving bars (both bright and dark). 3. A total of 60 S cells out of 85 (70.6%) and 90 C cells out of 101 (81.8%) responded to the motion of visual noise. Responses of most C cells were sustained, i.e., their discharge rate was maintained at a constant level throughout presentation of the stimulus. On the other hand, responses of the majority of S cells were characterized by several bursts of discharges. On average, optimal firing rates were greater for gratings than for noise. 4. For practically all cells, responses to noise varied as a function of direction of motion. The mean direction bandwidths were, respectively, 43 +/- 24 degrees and 48 +/- 23 degrees (mean +/- SD) for S and C cells. In both groups, neurons were more broadly tuned for the direction of noise than that of gratings (t-test, P < 0.001). We rarely observed bimodal tuning curves for noise, with each peak lying on either side of the orientation curve. These results could be expected if one considers texture stimuli not in the space domain (as dot patterns) but in the frequency domain, i.e., patterns containing all spatial frequencies and orientations. 5. In general, the direction indexes of S and C cells were similar whether they were stimulated by drifting noise or gratings. S cells had a slight tendency to be more direction selective for noise than for gratings. 6. For all S and C cells tested, responses to noise varied as a function of drift velocity. The mean optimal velocity was 12.9 and 10.2 degrees/s for S and C cells, respectively (t-test, P > 0.05). Most cells were band-pass with mean bandwidths of 2.2 and 2.7 octaves for S and C cells, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Hospitalizations of children and access to primary care: a cross-national comparison.
In the United States, hospital admissions for conditions sensitive to primary care are related to socioeconomic characteristics. The authors compare the prevalence of avoidable hospital admissions and their relationship to socio-economic and primary care characteristics in Spain and the United States. A case-control analysis of the relationship between avoidable hospitalizations and socioeconomic characteristics (illiteracy, unemployment, income) and primary care characteristics (type of physician and facilities for primary care) of children's area of residence was conducted in Spain. Bivariate statistical tests and conditional logistic regression were used to test the strength of the association among the variables, and to calculate the probability of being admitted to hospital for treatment of an ambulatory care sensitive (ACS) condition. Neither socioeconomic nor primary care characteristics affected this probability, and the rate of admission for ACS conditions was lower in Spain than in the United States. The provision of universal financial access to care and the availability of a consistent and accountable primary care provider are associated with lower hospitalization rates for conditions that are preventable with good primary care.
Ambulatory Care↗
Neuromodulatory effects of angiotensin II in the visual layers of the rat superior colliculus.
Recent autoradiographic studies have revealed the presence of both AT1 and AT2 angiotensin II (AngII) receptor subtypes in the superficial layers of the rat superior colliculus (SC). We have investigated the effects of activating these receptors on visually evoked potentials (VEP) in the SC of adult rats. A recording injecting microelectrode filled with AngII was lowered into the superficial layers of the SC. AngII was injected at concentrations varying from 10(-4) to 10(-10) M. Injection of the peptide yielded a reduction in the amplitude of the VEP. This reduction usually occurred within 2-3 min following AngII injection with a 50% recovery of most of the signal 20-30 min thereafter. AngII did not modify the signal when injected in collicular layers ventral to the stratum opticum. Furthermore, concomitant injection of AngII with the specific AT, receptor antagonist Losartan failed to reduce the evoked response suggesting that the effects of AngII in the SC are likely mediated by AT1 receptors.
Angiotensin II↗
Visual cortical neuron responses to drifting sine-wave gratings in rabbits.
Neurons of area 17 (V1) in rabbits were stimulated with drifting sine-wave gratings. Animals were anesthetized and paralyzed under conventional methods to record action potentials of single cells using tungsten-in-glass micro-electrodes. Neurons responded in modulatory or unmodulatory patterns depending on whether cells were of the simple or complex type, respectively. In the spatial domain, most cells were Low-Pass and Band-Pass, with no recordings of High-Pass units. In the temporal domain, Low-Pass, Band-Pass and High-Pass behaviours were found. Rabbits appeared to exhibit all types of pattern responses found in other foveate mammals, including special-complex and end-stopping units. However, in the majority of cells, there was a shift towards the lower end of the spatial frequency spectrum. For instance, the optimal spatial frequency was in the vicinity of lc/d while in the temporal domain, some units responded optimally at 10 c/s. In conclusion, it appears that rabbit cortex contain neurons which are selective for spatial frequency in a manner comparable to that seen in cat and monkey.
Animals↗
Effects of dextromethorphan on ischemia induced electroretinogram changes in rabbit.
The present study was undertaken to determine whether dextromethorphan (DM), a potent N-methyl-D-aspartate antagonist, could attenuate the effects of ischemia on rabbit ERG. Retinal ischemia was induced by increasing intraocular pressure to 120 mm Hg for 30, 60, or 90 min. DM was intravenously administered before ischemia and maintained throughout the entire experimental period. ERGs were recorded prior to, during, and after ischemia. The results indicate that the b-wave hyperresponses and the delays in implicit times induced by 30 min. ischemia were suppressed by the administration of DM. Similar findings were obtained when ischemia lasted for 60 min, except that DM did not improve delayed implicit times, suggesting that cellular injury is still present. ERG changes resulting from 90 min ischemia were not reversed by DM treatment. Effects of DM treatment on a-wave were less prominent. Together, our results further support that DM can to some extent alleviate ischemic injury in the rabbit retina.
Animals↗
[Hepatosplenic schistosomiasis: case report and clinical review].
Although seen rarely in Switzerland, schistosomiasis is a parasitosis affecting 200 to 250 million people round the world, mainly in tropical and subtropical regions of Africa, Asia, Central and South America. Depending on the parasitic species, the ureters and the bladder (S. haematobium) or the intestine and the liver (S. mansoni, S. japonicum, S. mekongi) are primarily involved. Other organs may be affected (lung, kidneys and central nervous system). Hepatosplenic schistosomiasis represents a special form of chronic infection by S. mansoni, S. japonicum or S. mekongi predominantly occurring in adolescents heavily and repeatedly infected during childhood, together with an additional genetic predisposition for the disease. Hepatosplenic schistosomiasis on a worldwide scale is one of the most prevalent causes of portal hypertension in man. We describe a 33-year-old Portuguese female with mansonian hepatosplenic schistosomiasis 12 years after leaving Africa, who had hepatosplenomegaly, portal hypertension, esophageal varices and hypersplenism. Splenomegaly and slight anemia had been known for years without prompting further work-up. Two months before diagnosis she had been delivered of a normal child after pregnancy without portal-hypertensive complications, namely esophageal hemorrhage. Because of placenta accreta, however, erythrocyte transfusion had been performed after delivery and was possibly responsible for hepatitis C found later on. Pathophysiology, clinical findings and therapy of the disease are discussed.
Adult↗
[A trial of modified triple therapy for the eradication of H. pylori in recurrent duodenal ulcer].
In a prospective trial we examined the efficacy and acceptability of a modified triple therapy in H. pylori (HP)-positive patients with recurrent duodenal ulcer disease. Oral administration of amoxicillin for two weeks was substituted for one single injection of intramuscular depot penicillin (benzathine penicillin G). Additionally, patients were given ornidazole 500 mg tid for 14 days and 120 mg colloidal bismuth sub-citrate qid for 28 days. The patients were investigated for H. pylori colonization using a rapid urease test (CLO), histology (H&E-, Giemsa stain), culture (including determination of the minimal inhibitory concentrations for metronidazole, penicillin G and amoxicillin) and H. pylori serology (Cobas Core Anti-H. pylori EIA, F. Hoffmann-La Roche). Control endoscopies using the same methods were performed 1 and 6 months after eradication therapy. The eradication rate was 50% and the ulcer healing rate 90% 1 month after therapy. Ulcers recurred in 2/3 of patients with persistent infection vs 0/5 of HP-eradicated patients after 6 months. Both successfully HP-eradicated patients and patients with treatment failure exhibited comparable decreases in mean serum IgG anti-HP concentration within 2 months. Discrimination between the two groups and hence identification of the eradication success by serology was not possible within a time period of 2 months. After 6 months, serum IgG anti-HP concentrations in non-HP-eradicated patients returned to pre-therapy values, in HP-eradicated patients the concentrations further decreased. The above-described modified triple therapy against HP cannot be recommended as a standard therapy, mainly because of the insufficient eradication effect.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Response properties of neurons in area 17 projecting to the striate-recipient zone of the cat's lateralis posterior-pulvinar complex: comparison with cortico-tectal cells.
The main input of the lateral part of the cat's lateralis posterior-pulvinar complex (LP-P) comes from the primary visual cortex. We investigated the response properties of cells in area 17 projecting to the striate-recipient zone (LP1) of the cat's LP-P complex. The cells' receptive fields were stimulated with drifting sine-wave gratings. Cells whose fibres terminate in the superior colliculus were also recorded, to determine how their properties compare with those of cortico-LP1 cells and to investigate the possibility that LP1 is innervated by collaterals of cortico-tectal units. A total of 26 cells in the striate cortex were identified by antidromic activation from the LP1 (mean latency 2.2 ms) and 22 from the colliculus (mean latency 2.5 ms). Only six cortical cells could be activated from the LP1 and the colliculus. All cortico-LP1 cells except for two responded to drifting sinusoidal gratings with unmodulated discharges (AC/DC ratios < 1). On the basis of their modulation index, these units were classified as complex cells. All cortico-LP1 cells were selective for the orientation of gratings (mean bandwidth of 28 degrees). There was a tendency for cortico-LP1 cells to prefer vertical and horizontal orientations. More than half of these cells (57%) were direction selective. Strong orientation anisotropies were also found in the receptive fields of cortico-tectal cells, since almost all units responded preferentially to horizontally oriented gratings.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Functional organization of the projections from the rabbit's superior colliculus to the lateral posterior nucleus.
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Animals↗
Responses of cells in cat's area 17 to random dot patterns: influence of stimulus size.
We have investigated both the response of cells in the striate cortex to a moving random dot pattern (visual noise) and the extent to which these responses depend on stimulus size. Cell receptive fields (RF) were classified according to the level of modulation of their response to sinusoidal gratings and the spatial arrangement of their ON and OFF regions. Our results indicate that most complex and simple cells respond to visual noise. The amplitude of these responses depend largely on the area of the visual field that was stimulated. Most cells were optimally activated when the noise covered a region much larger than the RF. Our results suggest that the area beyond the classical RF may contribute to the cells' responsiveness to noise.
Animals↗
Essential mixed cryoglobulinemia and IgA nephropathy, an infrequent association.
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Cryoglobulinemia↗
[Respiratory muscle training or rest].
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Exercise Therapy↗
[Colonoscopic endosonography in the diagnosis and follow-up care of colorectal tumors].
We studied the usefulness and accuracy of a flexible endoscopic ultrasound system (EUS) in preoperative staging of tumor invasion and involvement of lymph nodes of rectal tumors. Comparison of preoperative EUS findings with histopathologic TNM classification (UICC 1987) was possible in 12 patients. The depth of tumor invasion was correctly staged in 9/12 patients (75%), and lymph node staging was correctly predicted in 9/12 patients (75%). Our results indicate that flexible coloscopic ultrasonography is as accurate as rigid systems for staging of colorectal cancer. It will become a sensitive method for early diagnosis of local recurrence. The flexible endoscopes are well tolerated by patients and more proximal lesions which cannot be reached with the rigid instruments can also be examined.
Colonoscopy↗
[Helicobacter pylori colonization of the gastric remnant following partial resection].
Colonization by Helicobacter pylori (HP) in 53 patients after remote gastric surgery and Roux-en-Y anastomosis was investigated using a rapid urease test (CU-Test) and histology (H&E and Giemsa stain). The pH-value of gastric juice was measured. HP infection of the gastric remnant was found in 56% of 43 patients after partial resection and in no case after total gastric resection. HP-positive and HP-negative patients were comparable in age, sex distribution, indication and technique of gastric operation (except for total gastrectomy with jejunal gastric replacement), intake of acid inhibiting drugs and antibiotics was well as in the presence or absence of a macroscopically visible pathology of the gastric mucosa. On the other hand, the two groups differed in their histological findings, pH-value of gastric juice and time interval since surgery. HP infection of gastric remnants is associated with significant glandular atrophy and an additional rise in gastric intraluminal pH compared with HP-negative patients. Both changes may involve an increased risk for gastric cancer. In this report on patients with Y-en-Roux operation there is no decrease in gastric HP-colonization with an increasing interval since the time of operation, but rather an increase. This phenomenon seems to depend on the absence of enterogastric reflux.
Anastomosis, Roux-en-Y↗
[Endosonography: progress in the diagnosis of endocrine pancreatic tumors].
Diagnostic procedures for secreting endocrine pancreatic tumors comprise biochemical tests, CT scans, conventional abdominal sonography, angiography and occasionally MR imaging and isotope scans. Due to their small size, insulinomas and gastrinomas, the most common of these tumors, elude these diagnostic procedures. Preoperative sonography and CT scans were negative in over 60%, angiograms in 35% of the patients. The example of a patient with insulinoma demonstrates that in the future endosonography will offer itself as an accurate method with little risk.
Aged↗
Visual responsiveness and direction selectivity of cells in area 18 during local reversible inactivation of area 17 in cats.
We have investigated the effects of inactivation of localized sites in area 17 on the visual responses of cells in visuotopically corresponding regions of area 18. Experiments were performed on adult normal cats. The striate cortex was inactivated by the injection of nanoliters of lidocaine hydrochloride or of gamma-aminobutyric acid (GABA) dissolved in a staining solution. Responses of the simple and complex cells of area 18 to optimally oriented light and dark bars moving in the two directions of motion were recorded before, during, and after the drug injection. Two main effects are described. First, for a substantial number of cells, the drug injection provoked an overall reduction of the cell's visual responses. This nonspecific effect largely predominated in the complex cell family (76% of the units affected). This effect is consistent with the presence of long-range excitatory connections in the visual cortex. Second, the inactivation of area 17 could affect specific receptive-field properties of cells in area 18. The main specific effect was a loss of direction selectivity of a number of cells in area 18, mainly in the simple family (more than 53% of the units affected). The change in direction selectivity comes either from a disinhibitory effect in the nonpreferred direction or from a reduction of response in the preferred direction. It is proposed that the disinhibitory effects were mediated by inhibitory interneurones within area 18. In a very few cases, the change of directional preference was associated with a modification of the cell's response profile. These results showed that the signals from area 17 are necessary to drive a number of units in area 18, and that area 17 can contribute to, or at least modulate, the receptive-field properties of a large number of cells in the parastriate area.
Animals↗
Direction selectivity of cells in the cat's striate cortex: differences between bar and grating stimuli.
We have investigated the notion that directional responses of cells in the visual cortex depend on the type of stimulus used to drive the cell. Specifically, we have asked if sinusoidal gratings provide a different estimate of direction selectivity than bars that are brighter or darker than the background. Using standard techniques, we recorded from 176 cells in the visual cortex of nine cats. For each cell, bright bars, dark bars, and sinusoidal gratings were presented in a randomly interleaved fashion. Complex cells exhibited around twice as many direction-selective as nondirection-selective responses. Estimates of direction selectivity were nearly identical for bright and dark bars and for gratings. For simple cells, a similar ratio of direction-selective to nondirection-selective responses was observed for gratings. However, a larger proportion of simple cells were classified as direction selective when bars were used for stimulation. A simple cell that exhibited direction selectivity to a grating behaved in a similar manner when stimulated with bright or dark bars. However, in contrast to complex cells, some simple cells classed as directionally nonselective on the basis of their responses to gratings, displayed directionally selective behavior to bars. In addition, the preferred directions for dark and bright bars sometimes differed. These results demonstrate that the classification of a simple cell as directionally selective or nonselective can depend critically on the visual stimulus used.
Animals↗