Selective nicotinamide adenine dinucleotide phosphate-diaphorase histochemical labeling of Müller radial processes and photoreceptors in the earliest stages of retinal development in the tadpole

To investigate potential sources of nitric oxide production in the early stages of retinal development we used, in the tadpole, nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry that was reported to reveal nitric oxide synthase isoforms in the retina. In the first stages of optic vesicle differentiation, prior to optic cup invagination, histochemical positivity was detected in the radial processes of Müller cells, that provide a scaffold for migrating retinal neuroblasts, and was soon followed by intense staining of photoreceptors. These events preceded retinal laminar patterning and the appearance of histochemical positivity in other retinal cell populations. The findings indicate that nitric oxide synthase is expressed during early retinogenesis at selective sites, which are implicated in the guidance of migrating cells and in phototransduction.

Degranulation, density, and distribution of mast cells in the rat thalamus: a light and electron microscopic study in basal conditions and after intracerebroventricular administration of nerve growth factor

In the adult rat brain mast cells reside selectively in the thalamus. We investigated thalamic mast cells stained by acidic toluidine blue or pinacyanol, and with histamine immunocytochemistry, focusing on their state of activity revealed by degranulation. Mast cells exhibited perivascular prevalence and high quantitative variability, between cases and in different sections, with no asymmetry or topographical selectivity in thalamic nuclei. Pinacyanol, alone or with erythrosine, stained mast cells with higher sensitivity than toluidine blue. However, toluidine blue was highly predictive of pinacyanol staining and provided the best resolution of mast cell cytoplasmic features. Histamine immunocytochemistry labeled 61% of pinacyanol-stained mast cells. Intensely toluidine blue-stained granulated cells, as well as cells exhibiting different degrees of degranulation that paralleled lighter staining, were observed. The response of thalamic mast cells to intracerebroventricular administration of nerve growth factor (NGF) and control cytochrome-c injections was evaluated after 2, 24, and 72 hours. No obvious changes in mast cell number or distribution were found after treatment, but massive degranulation was frequently observed after NGF administration. Significant decrease of staining intensity of mast cells, supporting enhanced degranulation, was documented in NGF-treated animals by quantitative image analysis. Ultrastructural features of mast cell degranulation, with granule coalescence and matrix dissolution, were detected in untreated and NGF-treated cases. The findings point out that mast cells are active in the thalamus in basal conditions and that NGF has the potential to elicit long-lasting degranulation of thalamic mast cells in vivo, exerting a direct effect and/or priming these cells to react to endogenous stimuli.

[Coronary angioplasty and stent placement through the radial artery. Report of a case]

Coronary angiography and percutaneous treatment of stenotic lesions have expanded in the last few years, due to availability of better diagnostic equipment. The femoral technique applied to this aims has prevailed, considering its efficacy, safety and wide acceptance. Since the beginning of this decade, an alternative access has been developed, in relation to miniaturization of the required elements to perform coronary diagnostic and therapeutic procedures. This new radial artery access is supported by multiple reports from many centers around the world that are increasingly using the technique. With this access it is possible to perform all the regular procedures done regularly through the femoral route. This case report illustrates a coronary angiography study through the radial access, followed by a stent implantation, through the same route.

Nociceptive stimulation induces glutamate receptor down-regulation in the trigeminal nucleus

The dorsal horn of the subnucleus caudalis of the spinal trigeminal nucleus is a relay of oro-facial pain transmission; increase in subnucleus caudalis neuronal activity in response to tissue injury affects the level of chemical mediators participating in nociceptive processing. We investigated, by means of immunocytochemistry, the expression of N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) glutamate receptor subunits in this nucleus in a model of inflammation. Rats injected with formalin in the whisker pad were compared with saline-injected control rats. One and two days after formalin injection, the immunostaining of cell bodies and neuropil of the AMPA receptor subunits GluR1 and GluR2/3 was markedly decreased in the ipsilateral superficial laminae of the subnucleus caudalis compared to the contralateral side. Side differences were not evident in the saline-treated animals. The down-regulation of AMPA GluR1 and GluR2/3 was no longer detectable in the subnucleus caudalis three days after formalin injection. No side difference was detected in the N-methyl-D-aspartate receptor subunit NR2A/B immunoreactivity of the subnucleus caudalis at any time-point in the formalin-injected animals. The modulation of AMPA receptor may be related to the decrease of hyperalgesia evident 1 h after formalin injection, in spite of the increasing perioral inflammation evident later on and characteristic of the formalin model. The present findings point out a selective down-regulation of AMPA receptor subunits in the transduction of trigeminal pain. These data also support the involvement of glutamate receptor subunits in the processing of trigeminal inflammation induced by noxious chemical stimulation.

Heart rate variability in severe aortic stenosis

BACKGROUND AND AIM OF THE STUDY

Autonomic dysfunction may be a risk factor for the generation of arrhythmias and sudden death in patients with severe aortic stenosis; thus, patients with this condition were studied to assess cardiac autonomic function.

METHODS

Twelve patients (five males, seven females; mean age 63 +/- 13 years) with severe symptomatic aortic stenosis before and after aortic valve replacement, were compared with a control group matched by age and sex. In the study group, mean fractional shortening was 36.5 +/- 5% and maximal aortic gradient 94.7 +/- 12 mmHg, assessed echocardiographically. Autonomic dysfunction was evaluated by following heart rate variability in both time and frequency domains. Spectral analysis was assessed at very low frequency (VLF: 0.017-0.05 Hz), low frequency (LF: 0.05-0.15 Hz) and high frequency (HF: 0.15-0.50 Hz). Heart rate variability was analyzed during three intervals, between 6:00-8:00 am (morning), 14:00-16:00 (afternoon) and 02:00-04:00 (night), and re-evaluated at 8-10 months after aortic valve replacement.

RESULTS

Compared with controls, patients with aortic stenosis presented a significantly lower heart rate variability in the morning and afternoon, analyzed either by time or frequency domain: 50 +/- 22 versus 132 +/- 52 ms (p < 0.05); VLF 5.0 +/- 1.5 versus 7.9 +/- 1.4 ln (ms)2 (p < 0.05); LF 4.9 +/- 1.7 versus 7.5 +/- 1.8 ln (ms)2 (p < 0.05); HF 5.3 +/- 1.4 versus 7.5 +/- 1.8 ln (ms)2 (p < 0.05). Results at night showed a similar tendency, but were not statistically significantly different. At 8-10 months after aortic valve replacement, heart rate variability was increased significantly during the morning, from 50 +/- 22 to 79.5 +/- 22 ms (p < 0.05); VLF from 5.0 +/- 1.5 to 6.7 +/- 0.8 ln (ms)2 (p < 0.05); LF from 4.9 +/- 1.7 to 6.2 +/- 1.3 ln (ms)2 (p < 0.05). HF values tended to increase, though not significantly so. During the remainder of the day there was also a non-statistically significant increment in all values of heart rate variability.

CONCLUSIONS

The study results suggest that patients with severe symptomatic aortic stenosis present with autonomic dysfunction that tends to normalize within the first year of valve replacement.

[Unstable angina: invasive or conservative management?]

Acute coronary syndromes without ST segment elevation (Non-Q-Infarction and unstable angina) share a common pathophysiology, have no indication of thrombolysis, and should not routinely be catheterized on an emergency basis on admission. They should be put in bed rest, given anti-ischemic medications, aspirin and heparin. The small group of patients that do not stabilize with this medical regimen, should be catheterized, in order to have revascularization if they have the appropriate anatomy. There is nowadays a great controversy in the best management strategy for the larger group of patients that becomes stable after medical treatment installation. The invasive strategy proposes early, routine coronary angiography, and revascularization when anatomy is appropriate. The conservative strategy proposes continued medical treatment with invasive management only indicated by development of spontaneous or inducible ischemia. These two alternative strategies have been tested recently in large, prospective, randomized clinical trials: there is not a definitive answer, but the provisional guideline is that both are reasonably safe and effective.

[Variability of the heart rate: its physiopathological basis and its use as prognostic index after acute myocardial infarction]

The analysis of heart rate variability studies the normal oscillatory changes of the cardiac cycle. These changes are periodical or incidental and are controlled by humoral, sympathetic and parasympathetic stimuli. Frequency domain and time domain are the methods most used to assess heart rate variability. Time domain analyses variations of cardiac cycle using the standard deviation of RR intervals in 24 hours (SDRR) and the percentage of difference between adjacent normal RR intervals of more than 50 ms (pNN50). Frequency domain, converts beat to beat fluctuation of heart rate into different components of frequency by a fast Fourier transformation. They are classified, according to their magnitude, in high frequency (> 0.15 Hz), low frequency (0.04-0.15 Hz), very low frequency (0.003-0.04 Hz) and extremely low frequency (< 0.003 Hz). The high frequency fluctuations are predominantly related to parasympathetic activity whereas the low frequency fluctuations are related to sympathetic and parasympathetic activity. The physiology of very low and extremely low frequency fluctuations remains unclear. Many reports have shown that a decrease in heart rate variability after myocardial infarction may independently identify patients at risk for sudden death. However, the physiopathologic basis of these findings is not yet elucidated.

[Primary coronary angioplasty as a choice treatment in the 1st 6 hours following acute myocardial infarction]

Primary coronary angioplasty as treatment of acute myocardial infarction preserves more myocardium and has a lower mortality than thrombolysis. Aiming to assess the feasibility of its use in Chile, we studied 64 patients aged 59 +/- 2 years old, 27 with an anterior wall and 37 with an infero-lateral wall acute myocardial infarction of 118 +/- 62 min of evolution. Coronary angiography, performed 98 +/- 47 min after diagnosis, showed non significant disease in one, one vessel disease in 26 (40%), two vessel disease in 17 (27%) and three vessel disease in 20 (31%) patients. Responsible arteries for infarction were the anterior descending in 26 (40%), circumflex in 9 (14%), right in 27 (42%), a saphenous bridge in one and left main disease in one patient. In one patient with an obstruction over 50% and in two patients with left main disease, angioplasty was not attempted. The procedure was successful (defined as a residual lesion of less than 50%) in 56 of 61 patients (92%) and failed in four. One patient was re-perfused with intracoronary streptokinase. The delay in reperfusion was lower during working than non-working hours (89 +/- 48 vs 113 +/- 39 min). Four patients (6%) died during hospitalization, two had a reinfarction, two had a new vessel occlusion and three had a spontaneous ischemia. Eleven patients were operated during hospitalization and in two this was an emergency procedure. After 1993, mortality was lower (one of 55 patients) than before (three of nine). It is concluded that early coronary angioplasty in acute myocardial infarction is feasible in Chile, with a high degree of success.

[Adult pulmonary stenosis: percutaneous balloon valvuloplasty]

The results of balloon valvuloplasty as treatment for pulmonary stenosis in 8 adults (6 male) whose ages ranged from 17 to 58 years are presented. Three patients had been subjected to cardiac surgery 32, 40 and 10 years before. The procedure was performed through the right femoral vein using one or two balloons with a diameter of not less than 20 mm, without complications and excellent tolerance. The pulmonary gradient and the right ventricular pressure were reduced in 7 patients from 81.4 +/- 26.9 to 26.6 +/- 11.3 and from 99.3 +/- 25.5 to 47.7 +/- 13.6 mm Hg respectively (p < 0.0005). During follow up, 6 of the patients have remained in functional capacity I and in two, Doppler ultrasound examination showed a further reduction in valvular gradient. These results are in accordance with other reports and confirm that this technique is the treatment of choice for adult pulmonary stenosis.

Neuronal IFN-gamma in tuberomammillary neurones

Neuronal interferon-gamma (N-IFN-gamma), recently isolated from the nervous system, has a molecular weight distinct from that of lymphocyte-derived IFN-gamma, but crossreacts immunologically and shares certain bioactivities with this cytokine. In the rat brain N-IFN-gamma-immunoreactive perikarya were concentrated in the hypothalamic tuberomammillary nuclei; some immunostained neurones were also detected in the dorsal pontine tegmentum. Immunopositive nerve fibres were profusely distributed through the periventricular hypothalamus and midline thalamus. Scattered fibres occurred diffusely through the brain, ramified in the subpial layer and also surrounded intrathecal vessels. A dense concentration of puncta was detected in the suprachiasmatic nuclei and in the molecular layer of the hippocampal dentate gyrus. A role of N-IFN-gamma in immunological reactions and in modulation of selective brain functions is suggested.

[Percutaneous mitral valvuloplasty in 2 pregnant women]

In women with a significative mitral stenosis that become pregnant, medical treatment has limitations and surgical treatment is associated with maternal and fetal mortality. We report two pregnant women in whom a mitral valvuloplasty was performed in weeks 30 and 32 of pregnancy, using the single balloon Inoue technique. The indication for the procedure was the persistence of functional capacity IV heart failure in spite of hospital bed rest and the use of diuretics and beta-blockers. Basal mitral valvular area was 0.6 and 0.9 cm2 and improved to 1.7 and 1.8 cm2 after the procedure; six months later, the areas were 1.5 and 1.7 respectively. The procedure was well tolerated and was performed with abdominal and pelvic shielding. No complications occurred, which allowed hospital discharge in functional capacity I; they were readmitted for delivery, giving birth to two healthy girls. It is concluded that mitral valvuloplasty in safe and effective in pregnant women with mitral stenosis refractory to usual medical treatment.

[Percutaneous mitral valvuloplasty with the Inoue balloon. Report of a case]

Percutaneous mitral commissurotomy has recently been proposed as an alternative to surgery in mitral stenosis. The clinical and hemodynamic results are equivalent to those of surgical treatment. A new technique proposed by Inoue, using a single rubber balloon, with a low incidence of complications, can be performed in a shorter procedure time than the former double balloon technique. A 36 year-old woman with severe mitral stenosis, NYHA FC III, was treated percutaneously using a single rubber balloon designed by Inoue. Her mitral valve area increased from 0.83 to 1.96 cm2, her mean gradient decreased from 15 to 5.8 mmHg and the cardiac output increased from 4.14 to 5.3 l/min. Total procedure time was 2 h and the radioscopic time was 15 min. The follow-up at the fourth month showed persistence of the mitral valve area (2 cm2 at doppler measurement) and the patient was asymptomatic (NYHA FC I). A description of the technique is presented.

Suicidal behavior in Italy: data, trends and guidelines for a suicide intervention/prevention policy

Even though in Italy, as in the majority of Mediterranean countries, the increase in suicide rates is not among the highest in Europe, between 1969 and 1989 it showed a sharp upswing (+43% among males and +31% among females). In terms of geographical differences, the regions with the highest suicide rate are the northern ones (up to twice the national average). The age groups with the highest suicide risk are those over 74 years (in 1989 the rate among males over 65 was the highest of all: 31.3 per 100,000). The differences in the between-sexes distribution show that among females over 65 years old the suicide rate rose by 70% between 1974 and 1989, versus 77% for males of the same age. The preliminary epidemiological results of one of two Italian centers are presented. These centers are collaborating with the WHO/EURO Multicenter Study on Parasuicide; parasuicide rates are higher for females than for males (55.9 per 100,000, as against 38.1 for males), while the age group at highest risk is seen to be young women (15-24 years), with a specific rate of 115.6.

[Percutaneous valvuloplasty: a decade of continuous progress]

Percutaneous balloon valvuloplasty is an interventional procedure designed to treat valve stenosis. The indications, techniques and results depend on the valve being opened. It is currently the treatment of choice for pulmonary valve stenosis. It is an excellent alternative to surgery for mitral stenosis in patients with mobile valves and little abnormality of the subvalvular apparatus. In aortic stenosis it constitutes a gratifying palliative procedure in older patients at high surgical risk. Longer observation is needed to better appreciate the results and indications of balloon valvuloplasty.

[Incidence of myocarditis in patients with dilated cardiomyopathy]

We performed right ventricular endomyocardial biopsies in 23 patients with dilated cardiomyopathy aged 45 +/- 14 years. All patients had congestive heart failure of unknown etiology dating up to one year before the procedure (57% less than 3 months). NYHA functional class was II in 5, III in 12 and IV in 6 patients. All patients had evidence of systolic dysfunction and a dilated left ventricle (LV diastolic dimension 68 +/- 11 and systolic dimension 55 +/- 11). Definite evidence of myocarditis, based on findings of inflammatory infiltrate and cellular damage, was found in 6 patients (26%), borderline myocarditis in 9 and abnormalities consistent with dilated cardiomyopathy in 8. The incidence of myocarditis here reported is lower than previously figures based on findings of more than 5 lymphocytes per high power field. In this series, clinical and functional aspects of heart failure did not differ in patients with or without evidence of myocarditis.

[Cardiopulmonary resuscitation]

Cardiopulmonary resuscitation has been used for over 25 years. Recent developments related to a better understanding of the physiology of external massage and to the effect of drugs such as calcium and bicarbonate during cardiac arrest have improved the results of cardiopulmonary resuscitation.

[Percutaneous aortic valvuloplasty: immediate results in calcified aortic stenosis]

Symptomatic calcific aortic stenosis in elderly patients has a poor prognosis and a relatively high surgical risk. Percutaneous aortic valvuloplasty is a new therapeutic procedure that may be applied in this group of patients. We report immediate results obtained with this technique in a cooperative study of 3 hospitals. In 16 of 19 patients we were able to locate a balloon catheter across the aortic valve following a femoral artery puncture. Mean age was 72 years and almost all patients were considered high surgical risk. Peak aortic gradient fell from 89 + 33 to 47 + 21 mmHg while valve area rose from 0.43 + 0.14 to 0.66 + 0.27 cm2; cardiac output remained unchanged. In 5 patients, an aortic valve area above 0.7 cm2 was obtained. Four patients needed blood transfusion, one developed pericardial tamponade and other recovered uneventfully from ventricular fibrillation. One patient died hours after the procedure in a low output state probably related to aortic insufficiency. We feel that aortic valvuloplasty is indicated in patients with severe calcific aortic stenosis and high surgical risk. Moderate improvement can be obtained with risks commensurate with the severity of the illness.

[Association of coronary disease and valve diseases: implications for coronariography indication]

We studied 111 patients with valvular heart disease in order to detect associated coronary artery disease (CAD). Fifty had aortic valve disease, 47 mitral lesions and 14 mitro-aortic disease. Coronary angiography was performed in all subjects above 50 years of age and in 13 younger subjects with angina, atypical chest pain, prior myocardial infarction or unexplained left ventricular disfunction. Eight subjects (7.2%) had significant CAD: 1 with triple, 2 with double and 5 with single vessel disease. CAD was diagnosed in 11.5% of 26 patients with angina, in 6% of 17 patients with atypical chest pain and in 6% of 68 patients without pain. CAD was present in males only above age 55. We conclude that in our population, with low incidence of CAD, the association of this disease and valvular heart disease is unusual. Coronary arteriography would be unnecessary in these patients except in the presence of marked risk factors or other clinical findings suggesting CAD, like angina or prior myocardial infarction.

[Myocardial perfusion during exercise and rest in coronary patients. Evaluation with a thallium 201 analog (isonitrile-technetium 99 m)]

Isonitrile-technetium, a Thallium 201 analog, was used for myocardial perfusion imaging in 12 patients with known coronary heart disease. 10-40 mCu of the isotope were injected at maximal effort during a Bruce stress test. Imaging was performed using 3 projections immediately after exercise and 24 hr later, using a gamma camera attached to a computer. Myocardial necrosis was detected with a sensitivity of 89% and specificity of 63%. Corresponding figures for stress induced ischemia were 89% and 100%. Accurate localization of ischemia or necrosis was obtained in 70% of all cases, improving to 100% in cases of total artery occlusion. These results, similar to those reported in the literature, encourage the use of Tc labeled isonitrile for myocardial perfusion imaging whenever Thallium 201 is difficult to obtain.