Effect of exercise on plasma atrial natriuretic factor and cardiac function in men and women

In order to provide an integrated view of the physiology of atrial natriuretic factor (ANF) during exercise, we studied changes of its plasma concentrations in 13 normal subjects (seven males, six females) during three graded exercise levels and two periods of recovery (5 and 30 min), concomitantly with an assessment of cardiac function and ventricular volumes by multigated radionuclide angiography. Mean ANF levels (+/- SEM) increased in all patients at the second (P less than 0.002) and third (P less than 0.002) exercise levels, and after 5-min recovery (P less than 0.01): in males from 16 +/- 7 to 30 +/- 11 pg ml-1 at the third level, in females from 27 +/- 12 to 61 +/- 33 pg ml-1. Normal values were observed after 30-min recovery. Even if mean ANF levels were all higher in females, this difference did not reach statistical significance (P = 0.06). Significant decreases of ventricular volumes, as well as increases of ejection fraction and rate pressure product, were noted during exercise and were similar in both sexes. The kinetics of plasma ANF concentrations, compared with the increase of rate pressure product, was characterized by a latency and a remanence in recovery. This remanence, also present in the changes of ventricular volumes, supports the hypothesis that other factor(s) like catecholamines might still exert their influence after the exercise stops.     

A Comparison of the Physicochemical and Biological Properties of Mirtazapine and Mianserin

Although the chemical structures of the antidepressants mirtazapine and mianserin are closely related there are considerable differences in their biological properties. To find an explanation of this, various physicochemical properties of mirtazapine and mianserin were measured or calculated. Isosteric replacement of CH in mianserin by N in mirtazapine has profound effects on physicochemical properties. The charge distributions as indicated by NMR and calculated by semi-empirical quantum mechanics differ, not only for the changed aromatic A-ring (as expected), but also in other regions of the molecule. The N5 atom in particular, which is conjugated to the changed aromatic ring, is less negatively charged in mirtazapine than in mianserin. Consequently the oxidation potential of mirtazapine is significantly higher than that of mianserin. Another result of this difference in charge distribution is that the (calculated) dipole-moment vectors of the compounds are oriented roughly perpendicular to each other. The dipole moment of mirtazapine is, moreover, three times larger than that of mianserin; mirtazapine is, therefore, more polar than mianserin and this is reflected in a lower retention index. Finally, the basicity of mirtazapine, expressed as the pK_a value, is slightly but significantly lower than that of mianserin. The observed differences between the physicochemical properties of mirtazapine and mianserin result in different interactions of these two antidepressants with macromolecules, such as receptors, transporters and metabolizing enzymes; this might explain the differences observed in pharmacological activity and metabolic and kinetic behaviour, that is, the reduced affinity for the α₁-adrenoceptor and negligible noradrenaline reuptake of mirtazapine compared with mianserin.     

Interactions between peripheral blood CD8 T lymphocytes and intestinal epithelial cells (iEC)

Intestinal intraepithelial lymphocytes (iIEL) are primarily CD8 cells and most of them have a CD28^? phenotype, the phenotype of effector cytotoxic T cells. We asked whether the predominance of CD8⁺ CD28^? T cells in the gut may result from peripheral blood T cells preferentially migrating to the iIEL compartment and adhering to iEC. Compared with CD4 cells, adhesion of resting CD8⁺ T cells to iEC cell lines was significantly higher. Adhesion could be blocked with a MoAb to gp180, a molecule expressed on iEC which is known to interact with CD8/lck. No significant difference in the level of adhesion was observed between CD8⁺ CD28⁺ and CD8⁺ CD28^? T cells. Thus CD8 cells may preferentially migrate to the iIEL compartment, but loss of CD28 expression could occur in situ after migration. Consistent with this hypothesis, the CD8⁺ CD28^? cells became enriched after co-culturing T cells with iEC cell lines and primary iEC. Induction of the CD8⁺ CD28^? phenotype in cord blood and adult T cells was observed in co-cultures with iEC and also with mitogens and superantigens. In the latter case, CD28 down-modulation was seen specifically in the Vβ subset targeted by the superantigen, indicating that loss of CD28 expression is a direct result of T cell receptor (TCR)-mediated stimulation. The combined results suggest that CD8⁺ CD28^? T cells are antigen experienced T cells, and that they may have a survival advantage in the presence of gut epithelial cells in vitro. This may contribute to the predominance of CD8⁺ CD28^? T cells in the iIEL compartment.     

Immunomodulation by hydatid cyst fluid toxin (Echinococcus granulosus)

Since the experimental infection by hydatid cysts ( Echinococcus granulosus ) in mice causes immunomodulation of the host, the effects of hydatid fluid (HF) and fractions of HF were compared in vitro and in vivo . Fractions of HF were obtained using ammonium sulphate precipitation, chloroform/methanol extraction and thin-layer chromatography (TLC). HF proved to be toxic to murine peritoneal macrophages in vitro , and when macrophages were incubated with the different fractions of HF, most toxicity was found in a single TLC-purified fraction with an adjuvant-like effect on the production of specific antibodies against bovine albumin and human red blood cells in mice. Treatment of mice with the toxin caused a drop in the percentage of peripheral blood lymphocytes. Flow-cytometric analysis showed that T-cells from toxin-treated mice had lower membrane-CD3, CD4 and CD8 density, and had higher percentages of CD8⁺ splenocytes and CD4⁺ thymocytes expressing CD25. The toxin caused a down-regulation of CD4 and CD8 expression on thymocytes in vitro , that was dependent on the presence of macrophages. The results may attribute to these toxins a role in the host-parasite relationship of hydatidosis.     

The decay of house dust mite allergens, Der p I and Der p II, under natural conditions

Background: Fluctuations in the level of mite allergens in domestic house dust are the result of changes in the balance between synthesis, removal and decay. Purely physical forces as well as enzymatic degradation, mediated by house dust inhabiting microbes, may contribute to the decay of allergens in domestic dust. Knowledge about the speed of decay is essential for an understanding of the dynamics of allergen levels. Objective: The present study is a quantitative assessment of the speed of decay at nine combinations of temperature (15°C, 20°C and 25°C) and relative humidity (33%, 55% and 75%). Methods: Samples of mite infested material of an old rug were stored at these temperature/relative humidity-combinations for 6, 12 or 18 months, after the mites were killed by cither a freezing treatment or an acaricide (lindane). The microbes living in the rug presumably survive these treatments. Concentrations of Der p I and Der p II + Der f II. in extracts of the rug material, were measured by a radio immunoassay. Results: No significant changes in the levels of Der p I and Der p II +Der f II, could be detected even after 1¹/₂ year at a high temperature and humidity. Conclusion: These findings incidate that mite allergens can be extremely stable under normal domestic circumstances.     

Circulating filarial antigen in cats infected with Brugia pahangi is indicative of the presence of adult worms

Using counterimmunoelectrophoresis with rabbit antisera raised against soluble extracts of adult females of Brugia pahangi parasite antigen was detected in the serum of all cats repeatedly infected with B. pahangi. Antigen was never detected in uninfected cats. The antigen was associated with the presence of adult worms. Antigen was detected consistently in a cat that was amicrofilaraemic but at autopsy harboured only two or three adult worms. Conversely, some cats showed slowly declining numbers of microfilariae and, in these, circulating antigen declined before the number of microfilariae. Eventually no antigen was detectable in circulation whereas microfilariae, although in diminishing numbers, were still present. At autopsy no adult worms were found in these cats. Antigen also appeared in several cats before they became microfilaraemic.     

Computer simulation of the occlusal anatomy of the first mandibular molar after varying the determinants of mandibular movement in the CICERO CAD/CAM system

Static and dynamic occlusal interferences often occur in restorations. The CICERO CAD/CAM technique was used to control the occlusal dimensions of all‐ceramic restorations by setting the variables which determine the mandibular contact movements. The anatomy of the occlusal form of the (pre)molar teeth is influenced by the setting of the sagittal and transversal determinants of mandibular contact movements. In this study the variation in occlusal morphology of a high‐ and low‐limit setting of six variables was compared with an averaged setting. The settings (high, low and averaged, respectively) of the mandibular movement: the sagittal condylar (60°, 0°, 30°) and the incisal guide angle (60°, 0°, 30°) as well as the long centric articulation (1·2 mm, 0 mm, 0·6 mm) influence mainly the antero‐posterior direction, whereas the settings of Bennett movement (laterotrusion: 30°, 0°, 15°), Bennett side shift (laterotranslation: 1, 0, 0·5 mm) and the wide centric (lateral intercuspal contact area: 0·6, 0, 0·3 mm) will mainly influence the transversal direction of the mandibular movement. The influence of the variation of settings on ‘dynamic’ crown morphology as compared with the static crown morphology was studied by comparison of mesio‐distal and bucco‐lingual sections at the same occlusal position of the first lower molar design. Furthermore, the amount of material needed for the correction of the ‘static’ crown to avoid interferences in dynamic conditions was calculated. It appeared that most correction was needed for the ipsilateral settings: Bennett side shift (1·0 mm), Bennett movement (30°) and the Sag. Condylar guidance (0°) as well as the Incisal angle (0°), which could be studied in the bucco‐lingual sections. Also the Bennett side shift on the contra‐lateral side influenced the occlusal contour strongly, which could be seen in the mesio‐distal section. It was concluded that simulation of the influence of several types of determinants of mandibular movement on the three‐dimensional occlusal anatomy can be studied using the CICERO‐CAD/CAM technique. The ipsi‐ and contralateral Bennett side shift variation influenced the occlusal anatomy more than other variables.     

用Sauvegrain法测定青春期骨龄准确性的研究

背景：Sauvegrain方法是通过分析肘部X线片来评估骨龄，常用于青春期生长发育最为迅速的两年间的骨龄测定。本文旨在研究该方法的准确性以及在小儿骨科中的应用价值。 方法：Sauvegrmn法主要评估肘部的4个解剖标志点：外髁、肱骨滑车、尺骨鹰嘴突以及桡骨近端骨骺。它是一个27分制的评分系统。对上述结构所得的评分进行合计而得出一个总分，然后使用标准图表确定骨龄。让三位观察者分别利用该方法进行骨龄评估。三位观察者通过分析60个男孩和60个女孩样本左肘部的前后位和侧位X线片来测定骨龄，并将该结果与通过分析左手和腕部后前位X线片的Greulich和Pyle图谱而得出的骨龄结果进行比较。间隔4周后每个观察者再测定骨龄一次。 结果：通过分析肘部X线片的方法测定骨龄更为精确，因为采用该方法测定骨龄可以精确到半岁。根据观察者的评定，Sauvegrain法显示出很好的观察者之间的相关性（r=0．93）和可重复性（r=0．96）。Sauvegrain法与Greulich和Pyle图谱之间有很好的相关性（r=0．85）。然而，一些肘部生长中心显示出一种中间的发育形态，这种形态学不适合Sauvegrain法的评分。这就导致了数据分析时出现误差。我们建议对于这些样本设定中间评分，并且通过修改原始图表而使评分更为精确。 结论：改良的Sauvegrain法简单、可靠而且可重复性高，它补充了Greulich和Pyle图谱的不足。在临床实践中，骨骼成熟度可以通过骨龄、年生长率以及第二性征而得以很准确的评估。因此，当青春期需要进行骨骺或脊柱关节融合术时，这种方法对于确定手术时间具有重要意义。 可信水平：诊断性研究，Ⅱ级，进一步可信度参见作者介绍。