Spin-wave theory for the dynamics induced by direct currents in magnetic multilayers

A spin-wave theory is presented for the magnetization dynamics in a ferromagnetic film that is traversed by spin-polarized carriers at high direct-current densities. It is shown that nonlinear effects due to four-magnon interactions arising from dipolar and surface anisotropy energies limit the growth of the driven spin wave and produce shifts in the microwave frequency oscillations. The theory explains quantitatively recent experimental results in nanometric point contacts onto magnetic multilayers showing downward frequency shifts (redshifts) with increasing current, if the external field is on the film plane, and upward shifts (blueshifts), if the field is perpendicular to the film.

Immunolocalization of myosin Va in the developing nervous system of embryonic chicks

Myosins are molecular motors associated with the actin cytoskeleton that participate in the mechanisms of cellular motility. During the development of the nervous system, migration of nerve cells to specific sites, extension of growth cones, and axonal transport are dramatic manifestations of cellular motility. We demonstrate, via immunoblots, the expression of myosin Va during early stages of embryonic development in chicks, extending from the blastocyst period to the beginning of the fetal period. The expression of myosin Va in specific regions and cellular structures of the nervous system during these early stages was determined by immunocytochemistry using a polyclonal antibody. Whole mounts of chick embryos at 24-30-h stages showed intense immunoreactivity of the neural tube in formation along its full extent. Cross-sections at these stages of development showed strong labeling in neuroepithelial cells at the basal and apical regions of the neural tube wall. Embryos at more advanced periods of development (48 h and 72 h) showed distinctive immunolabeling of neuroepithelial cells, neuroblasts and their cytoplasmic extensions in the mantle layer of the stratified neural tube wall, and neuroblasts and their cytoplasmic extensions in the internal wall of the optic cup, as well as a striking labeling of cells in the apparent nuclei of cranial nerves and budding fibers. These immunolocalization studies indicate temporal and site-specific expression of myosin Va during chick embryo development, suggesting that myosin Va expression is related to recruitment for specific cellular tasks.

Cytochemical characterization of eosinophilic leukocytes circulating in the blood of the turtle (Chrysemys dorbignih)

Eosinophils and neutrophils are granulocytic leukocytes that are present in the blood of most vertebrates. Studies have been performed on lower vertebrates to understand the biological roles of the cells in defense mechanisms and to establish phylogenetic studies and new experimental models. Whether these 2 cell types exist in reptiles is a matter of controversy. In the blood of turtles there are 2 types of granulocytes that exhibit eosinophilia, one of them with round cytoplasmic granules and the other with elongated cytoplasmic granules. It has been suggested that these cells may be eosinophils in different stages of maturation but they also may be distinct cell types, i.e. eosinophils and neutrophils. In the present study, we characterized the 2 types of granulocytes that are present in the blood of Chrysemys dorbignih, using cytochemical techniques. Type I eosinophils showed activity of nonspecific esterase, peroxidase activity that is resistant to KCN, and basic proteins. Type II eosinophils exhibited activity of trimetaphosphatase, alkaline phosphatase, nonspecific esterase, peroxidase that is sensitive to KCN, and basic proteins. These observations indicate the existence of 2 distinct cell types in the blood of Chrysemys dorbignih, type I and type II eosinophils, that correspond to eosinophils and heterophils (neutrophils) of mammals and other vertebrates.

Cerebral venous sinus thrombosis in a neonate due to factor V Leiden deficiency

A case is described of cerebral venous sinus thrombosis due to factor V Leiden deficiency that occurred in the neonatal period, presenting with seizures. Diagnosis was based on ultrasonography, Doppler ultrasound (US) and magnetic resonance imaging (MRI). The aetiology was only recognized after blood-clotting tests, antithrombin III, C and S protein levels and factor V Leiden were studied. This situation was treated with intravenous heparin controlled by activated partial thromboplastin time (APTT). MRI angiography and Doppler US were important in the follow-up. It is important to assess periodically the neurological development of the baby and to prevent situations such as dehydration or severe infection, which can precipitate further thrombotic events. Molecular genetics allowed the identification of this trait in other family members.

CONCLUSION

In every newborn with a thrombotic episode, coagulation studies must be performed, including testing for activated protein C (APC) resistance. Doppler US flow measurement and the MRI studies provide the best tools for diagnosis and follow-up. Heparin should be given to double the initial individual APTT. It is important to prevent any risk situation such as dehydration or severe infection, which could lead to a recurrence of a thrombotic episode. Regular assessment of the child's neurodevelopment is an important aspect of further care.

Localization of peroxidase activity in blood mononuclear phagocytes in pacu fish (Piaractus mesopotamicus)

The localization of peroxidase activity in different cell regions is used as a criterion for classifying the stage of maturity of mammalian mononuclear phagocytes, with a positive peroxidase reaction indicating the presence of monoblasts, promonocytes, monocytes, and macrophages. Peroxidase activity was observed ultrastructurally in the circulating blood of pacu fish (Piaractus mesopotamicus), identifying monoblasts, promonocytes, monocytes, and macrophages. These observations suggest that differentiation of mononuclear phagocytes occurs in the blood circulation of fish, whereas in mammals, monoblasts and promonocytes are detected in bone marrow, with only monocytes detected in circulating blood and differentiation into macrophages occurring in other body compartments.

Bariatric surgery in a patient with possible psychiatric contraindications

Grade III obesity (BMI > 39.9 kg/m2) is considered a chronic disease where clinical and diet therapy show poor results, with high rates of relapse. The most consistent results are those obtained through surgical procedures. Several authors discuss the contraindications for the performance of anti-obesity operations. Psychiatric disorders are often considered contraindications to these operations, especially affective disorders, psychotic disorders and personality disorders. The authors report the case of a 37-year-old patient, with obesity history since the age of 12, and anorexiant abuse (amphetamine-derived substances) during 20 years, binge-eating episodes, purgative compensatory behaviors and recurrent depressive symptoms. She was submitted to anti-obesity surgery in August 2000 (BMI 40.2). The outcome is reported and a discussion of the possible psychiatric contraindications for the anti-obesity surgeries is proposed.

Morphology and histoenzymology of eosinophilic granulocytes in the circulating blood of the turtle (Chrysemys dorbignih)

The studies on the characterization of eosinophils and neutrophils/heterophils of turtles are contradictory. Some authors have pointed out the existence of two distinct cell types: eosinophils and heterophils. Other authors have proposed that eosinophils and heterophils may be the same cells in different stages of maturation. These interpretations are based only on a morphological analysis. In the blood of the turtle (Chrysemys dorbignih), a South American freshwater species, there are two types of granulocytes with eosinophilic staining pattern: the first with round cytoplasmic granules and the second with ellipsoidal cytoplasmic granules. In the present study by using histoenzymological methods for the analyses of enzymological cellular content, we found that the cells with round cytoplasmic granules were positive for nonspecific esterase and the cells with ellipsoidal granules were positives for acid phosphatase, alkaline phosphatase, nonspecific esterase and peroxidase. The results show that these cells are distinct cells and that the cells with ellipsoidal cytoplasmic granules have the same histoenzymological characteristics as the neutrophils/heterophils of mammalians and other vertebrates.

The thrombocyte aggregation process in the turtle Phrynopys hilarii (Chelonia). An ultrastructural study

This study investigates the thrombocyte aggregation process in the South American fresh water turtle (Phrynopys hilarii) using electron microscopy. Blood was taken from surgically exposed lateral neck vessels of ten turtles Phrynopys hilarii during the spring and summer seasons, when the mean temperature is 37 degrees C. Blood samples were fixed with Karnovsky solution for processing by transmission electron microscopy. The turtle thrombocytes were spindle-shaped with lobulated nuclei. Prominent vesicles and canaliculi were found throughout the cytoplasm. The cytoplasm organelles showed an agranular endoplasmatic reticulum, Golgi complex near the centrioles and scattered free ribosomes. These cells are similar to bird thrombocytes but distinct from fish and frog thrombocytes. Blood clotting time was 5 min +/- 30 sec measured by the Lee and White method. Structural alterations resulting from the aggregation process occurred after activation. Thrombocytes developed numerous filopodial projections, an increased number of vacuoles and changed from spindle to spherical shape. P. hilarii thrombocytes have different morphologic characteristics compared to other non-mammalian vertebrate cells. These cells can participate in the aggregation process, as observed in birds.

[Relationship between respiratory syncytial virus subtype and clinical severity in bronchiolitis]

BACKGROUND

Respiratory syncytial virus (RSV) is the most frequently implicated agent in bronchiolitis. The virus presents two antigenic subtypes (A and B). The results of studies on the relationship between viral subtype and clinical severity are conflicting.

PURPOSE

To evaluate whether the subtype of this virus constitutes an independent variable in the severity of clinical expression of RSV infection.

PATIENTS AND METHODS

We prospectively studied previously healthy children aged less than 2 years admitted for RSV infection during an epidemic season. Clinical presentation and evolution, laboratory and radiological aspects were compared in subsets of children infected with RSV subtype A or B. Clinical severity parameters included score and duration of respiratory distress, oxygen requirements, admission to the intensive care unit, mechanical ventilation and length of hospital stay.

RESULTS

Eighty-five patients were enrolled in the study (50 boys and 35 girls; mean age 4.8,4.3 months). Fifty-nine children were infected with RSV subtype A. No differences were found in age, sex or antecedents but children with subtype B were less likely to have been breast-fed. Clinical presentation and laboratory and radiological findings were similar in both groups. No statistically significant differences in clinical severity parameters were found between subsets A and B. Age less than 3 months was associated with greater duration of respiratory distress and longer hospital stay.

CONCLUSION

The results do not support the hypothesis that subtype A infection is associated with more severe respiratory syncytial virus disease.

Transradial approach for coronary interventions

OBJECTIVE

To assess the feasibility and safety of coronary interventions performed through the radial artery.

METHODS

We studied 103 patients with ages from 38 to 86 years (57+/-8.7), 90 (87%) males, and: radial pulse with a good amplitude, presence of ulnar pulse, a good collateral flow through the palmar arch assessed with the Allen's test.

RESULTS

The vascular approach was obtained in 97 (94%) patients, 88 (91%) treated electively and 9 (9%) during acute myocardial infarction, for primary angioplasty; 56 (64%) unstable angina; 22 (25%) stable angina; 10 (11%) were asymptomatic, 6 referred for recanalization of chronic occlusion and 4 silent ischemia in the first week after acute myocardial infarction. We approached 107 arteries: anterior descending artery, 49 (46%); right coronary artery, 27 (25%); circumflex artery, 25 (23%); diagonal artery, 6 (6%); and 2 saphenous vein bypass grafts. We treated 129 lesions: 80 (62%) B2 type; 23 (18%) B1 type; 17 (13%) C type; and 9 (7%). A type. There were 70 stents, and 59 balloon angioplasties performed. Thirty-two (33%) patients used GP IIb/IIIa inhibitors. The mean duration of the elective procedure was 42.3+/-12.8 min. Success, correct stent deployment and residual lesion <20%, was reached in 100% of the lesions treated with stent implantation; arterial dilation with residual lesion <50% was obtained in 96% of the lesions treated with transluminal coronary angioplasty (TCA). Complications, were: 1 (1.0%) non-Q-wave acute myocardial infarction; 2 (2%) hematomas in the forearm; and 2 losses of radial pulse.

CONCLUSION

Radial artery approach is practical and safe for percutaneous coronary interventions there was a low incidence of complications.

Magnon excitation by spin injection in thin Fe/Cr/Fe films

The technique of Brillouin light scattering is used to observe strong excitation of magnons in antiferromagnetically coupled trilayers of Fe/Cr/Fe at room temperature. The magnons are driven out of equilibrium by a microwave current applied in the trilayer through point contacts. The magnitude of the scattering intensity is investigated as a function of the magnon wave number and applied magnetic field. Confirming recent theoretical predictions, the observations provide strong evidence of electronic spin injection in the rf driving field.

Upper-body adiposity and risk of myocardial infarction

BACKGROUND

The relation between obesity and coronary heart disease (CHD) has long been studied, but no convincing conclusion has been drawn.

OBJECTIVE

To estimate the relative risk associated with upper-body adiposity which is at present believed to be a better predictor of CHD.

DESIGN

This was a community-based case-control study.

METHODS

We studied 338 consecutively admitted patients who had had their first acute myocardial infarction (AMI) and 662 community controls who had not suffered AMI selected as a random sample of adults living in the catchment area of the hospital. We defined three classes of body mass index (BMI) and waist: hip circumference ratio on the basis of tertiles of distribution for controls. Odds ratios (OR) were estimated using unconditional logistic regression. Separate models were built for men and women.

RESULTS

In univariate analysis we found a higher risk of AMI for men and women with hypertension, dyslipidaemia, diabetes and lower levels of education, for older women, for male smokers and for men with family histories of CHD. Both for men and for women a higher BMI was associated with a slightly higher risk, whereas the adjusted risk of AMI increased with increasing waist: hip circumference ratio [for men OR (second tertile)= 2.5, 95% confidence interval (CI) 1.3-4.9 and OR (third tertile)= 11.1, 95% CI 6.0-20.6; for women OR (second tertile) = 3.0, 95% CI 0.6-14.8 and OR (third tertile) = 14.1,95% CI 3.2-62.7]. This relation held for each BMI class and was stronger for classes of lower BMI.

CONCLUSIONS

Distribution of body fat rather than BMI is a strong marker of risk for AMI and there is a clear interaction between these two variables.

Tobacco smoking among Portuguese high-school students

The aim of this study was to evaluate the prevalence, behavioural patterns, and determinants of smoking among a large sample of high-school students from Porto, the second largest city in Portugal, information on sociodemographic characteristics and personal history of tobacco, alcohol, coffee, and illicit drug use was obtained from 2974 students, aged 12-19 years (48.7% female, 51.3% male), using an anonymous self-administered questionnaire. Crude and adjusted odds ratios (OR) were calculated by logistic regression analysis to estimate the association between smoking and the characteristics evaluated. Overall, 35.8% students had never smoked, 39.4% had tried it ("experimental" smokers) but were not smokers, 3.3% were former smokers, 6.6% occasional smokers, and 14.9% regular smokers. The mean age for starting smoking was 13.4 +/- 2.1 years for males and 13.4 +/- 1.6 years for females. The prevalence of current smoking was higher among males than females, but the difference was not significant. Male students were significantly more likely to smoke more cigarettes per day than were females. The prevalence of smoking was significantly associated with the following variables: being aged > 12 years; having parents who had attended school for < 4 years; having a mother (OR = 1.88), siblings (OR = 1.96) or friends (OR = 1.75) who smoked; low academic performance (OR = 1.74 for one or two failures and OR = 2.27 for more than two failures at school); and consumption of coffee (OR = 2.90), alcohol (OR = 3.53), or illicit drugs (OR = 6.69). The prevalence of smoking among adolescents increased with age. There is therefore a need for school-based tobacco prevention programmes which also deal with family influences on smoking.

A case of neonatal haemochromatosis

We describe a case of neonatal haemochromatosis, pointing out the difficulties in diagnosing this fatal disease, which here involved the early occurrence of hepatic carcinoma.

[The role of low-molecular-weight heparin in unstable angina, acute myocardial infarction and post-elective percutaneous transluminal coronary angioplasty]

PURPOSE

To evaluate the clinical efficacy and safety of subcutaneous (SC) low molecular weight heparin (LMWH) compared to intravenous (IV) non fractioned heparin (NFH) in unstable angina, acute myocardial infarction and post-percutaneous transluminal coronary angioplasty.

METHODS

From September/92 to April/94, 314 patients were randomized in two groups. Group I-- 154 patients treated with SC LMWH, using in the 1st phase SC LMWH with a dosage of 160 UaXa IC/kg/day (group IA--92 patients), and in the 2nd, a dosage of 320 UaXa IC/kg/day (group IB--62 patients). Group II--160 patients treated with IV NFH 100UI/kg (bolus), followed by 1000UI/h with adjusted dosage by activated partial thromboplastin time.

RESULTS

There was not a statistically significant difference among the three groups in relation to cardiac events, hemorrhagic complications and deaths.

CONCLUSION

The clinical efficacy and safety of SC LMWH in patients with unstable angina, acute myocardial infarction and post-percutaneous transluminal coronary angioplasty were similar to IV NFH with the dosages used in this study.

[Congenital rubella. Still with us]

After vaccination against rubella was introduced, the number of cases of rubella and congenital rubella syndrome decreased significantly. The presentation of a case report of rubella virus congenital infection with important sequellae, stresses the need to reinforce prevention. The existence of rare cases of reinfection imply good surveillance that gestations should be maintained even in women previously immune.

Motivation needs of sampled Fortune-500 CEOs: relations to organization outcomes

Motive scores (needs for Achievement, Affiliation, and Power) of the chief executive officers of the nation's 50 largest industrial firms were determined using content analysis of letters to stockholders contained in the firms' annual reports. The scoring method was a modification of the standard TAT scoring procedure. Results showed that chief executive officers' high need Achievement was correlated with relative growth in sales, while high need Power was correlated with relative growth in profits. Effects of need Achievement and need Power also were examined for return on equity and return on sales. Implications are discussed.

[Coronary transluminal angioplasty after the use of thrombolytic therapy in acute myocardial infarction]

PURPOSE

To present the Cardiology Institute of Rio Grande do Sul experience with percutaneous coronary angioplasty (PTCA), after thrombolytic therapy in acute myocardial infarction (AMI).

METHODS

Fifty-three patients with transmural AMI in whom early successful intravenous streptokinase recanalization was followed by PTCA. The mean age was 50 years, male patients were more frequent, the predominant area of infarct was anterior wall and more frequently the "culprit" coronary was the left anterior descendent. The main indication of PTCA was uniarterial lesion with less than 20 mm of length.

RESULTS

The success comes out in 44 patients (81.5%). Ten patients (18.5%) were considered unsuccessful and were referred to emergency bypass graft surgery. The in-hospital AMI rate after PTCA was 5.5%. In the follow-up the reestenoses rate was 11% and reocclusion was 3.7%. New PTCA was necessary in 3 patients (5.5%) and in one, by-pass graft (1.8%).

CONCLUSIONS

PTCA is an important and secure modality of complementary therapy after thrombolytic therapy with low morbidity and mortality.

[Bedside cardiac catheterization. Advantages and disadvantages]

Three hundred patients submitted to bedside heart catheterization (BHC) from 1973 to 1985 were studied, in order to assess advantages and risks of the procedure. Two-hundred and sixty seven patients (89%) suffered a myocardial infarction (MI) and 146 of them were in functional class (Killip) II, 36 in FC III and 71 in FC IV. Thirty cases were submitted to BHC due to congestive heart failure. BHC was successful in 288 patients (96%) and the wedge pressure (WP) could be measured in 236 cases (78.7%). The WP was less than 18 mmHg in 47.2% of the patients in FC II, in 44.9% of the patients in FC III and in 35.3% of those in FC IV. Minor complications occurred in 33 cases (11.0%); balloon rupture in 12 (4.0%), transient arrhythmias in 11 (3.7%) and lumen obstruction in another 10 cases (3.3%). Forty five patients (15.0%) presented major complications related to the procedure: pulmonary infarction (PI) in 18 cases (6%), phlebitis in 15 cases (5%), sustained arrhythmias in 10 cases (3.3%), pulmonary artery rupture and endocarditis each in 1 case. The mean age between the group of patients with and without complications was similar the maintenance time as greater in the group of patients with complications: 3.4 +/- 0.2 vs 2.7 +/- 0.1 days (p less than 0.05). We concluded that many patients with clinical evidence of heart failure had WP smaller than 18 mmHg, emphasizing the value of the procedure in patients with complicated MI. The maintenance time was associated with the occurrence of complications, mainly PI and phlebitis.

[Changes in the ST segment in unstable angina pectoris. Its prognostic value]

Out of 145 patients with unstable angina hospitalized at CCU of the Instituto de Cardiologia do Rio Grande do Sul (Brazil) in 1981, 69 were studied: group I = 23 case (33.3%) with transient ST segment depression, group II = 13 cases (18.8%) with transient ST segment elevation, group III (control) = 33 cases (47.8%) without acute EKG changes. Group I showed a higher incidence of double-triple coronary artery involvement: 71.4% VS 53.8 and 63.3% respectively (non significant). This group also showed a higher number of patients with severe angina and who suffered acute myocardial infarction during follow-up, although without statistical significance. There were 8 deaths (34.8%) in group I, 3 (23.1%) in group II and 4 (12.1%) in group III (chi 2 = 4.11, p greater than 0.05). The 36 months survival rate was lower in group I than in groups II and III: 52.9% VS. 75.2% (NS) and 89.7% (P less than 0.02) respectively. We conclude that acute EKG changes, mainly transient ST segment depression, in unstable angina, are markers of high risk patients.

Elevated proteinase activities in mouse lung tumors quantitated by synthetic fluorogenic substrates

Proteinase activities in malignant and normal lung tissues were measured using two synthetic substrates that consist of a fluorophor coupled to a peptide moiety. The hydrolysis of CBZ-Val-Lys-Lys-Arg-4-methoxy-2-naphthylamide and BZ-Gly-Gly-Arg-4-methoxy-2-naphthylamide were studied in homogenates of two types of mouse lung tumors, the Lewis lung tumor of the C57 black mouse and the KHT tumor of the C3H mouse. The activity of CBZ-Val-Lys-Lys-Arg-4-methoxy-2-naphthylamide hydrolysis had a pH optimum of 6.3 and a Km of 2.1 x 10(-4) M, required a thiol activator, and was inhibited by leupeptin suggesting the activity of a cathepsin B-like enzyme. The activity of BZ-Gly-Gly-Arg-4-methoxy-2-naphthylamide hydrolysis had a pH optimum of 6.7 and a Km of 3 x 10(-5) M. Lung tumor homogenates contained higher hydrolytic activities for both substrates than normal lung homogenates.