Analysis of cytosolic and lysosomal pH in apoptotic cells by flow cytometry

Several reports indicate that the cytosol is acidified during apoptosis although the mechanism is not yet fully elucidated. The most acidic organelle found in the cell is the lysosome, raising the possibility that lysosomal proton release may contribute to the cytosolic acidification. We here describe methods for measurement of the cytosolic and lysosomal pH in U937 cells by a dual-emission ratiometric technique suitable for flow cytometry. Cytosolic pH was analysed in cells loaded with the fluorescent probe BCECF, while lysosomal pH was determined after endocytosis of FITC-dextran. Standard curves were obtained by incubating cells in buffers with different pH in the presence of the proton ionophore nigericin. Apoptosis was induced by exposure of cells to 10ng/ml TNF- for 4h, and apoptotic cells were identified using a fluorescent marker for active caspases. By gating of control and apoptotic cells, the cytosolic and lysosomal pH were calculated in each population. The cytosolic pH was found to decrease from 7.2 ± 0.1 to 5.8s±0.1 and the lysosomal increased from 4.3±0.4 to 5.2±0.3. These methods will be useful in future attempts to evaluate the involvement of lysosomes in the acidification of the cytosol during apoptosis.     

Counts of Stromal Precursor Cells in Heterotopic Splenic Transplants in CBA Mice of Different Age

The content of stromal precursor cells in heterotopic splenic transplants from old and young mice changed appreciably after cross transplantation to old and young animals. The content of CFC-F in the youngold transplants decreased almost 1.5 times in comparison with the youngyoung transplants, the counts of CFC-F in oldold transplants were minimum in comparison with all other groups (2.5±0.1), while in the old young group transplants this value increased almost 8-fold (to 19.0±1.3) and surpassed the control level. Age-associated shifts in the splenic stromal tissue were determined by regulatory influences of the host, rather than by decreased count of stromal precursor cells in the tissue.__________Translated from Byulleten Eksperimentalnoi Biologii i Meditsiny, Vol. 139, No. 2, pp. 196–198, February, 2005     

Usefulness of low-priming-volume cardiopulmonary bypass circuits and dilutional ultrafiltration in neonatal open-heart surgery

In neonate open-heart surgery, cardiopulmonary bypass (CPB) with extreme hemodilution induces an increased capillary permeability and accumulation of extravascular fluid, resulting in organ dysfunction. We evaluated the effects of a reduced priming volume for CPB and dilutional ultrafiltration (DUF) during neonatal open-heart surgery. Nineteen consecutive neonates with complete transposition of the great arteries who underwent an arterial switch operation were retrospectively assigned into two groups: the high-priming-volume circuit group (group A, n = 9) and the low-priming-volume circuit group (group B, n = 10). Patients in group B underwent surgery with a miniaturized CPB circuit and using the DUF technique. The priming volume of group B was nearly two-thirds that of group A. The water balance value after CPB and surgery was significantly lower in group B (–126 ± 118ml, –116 ± 116ml) than in group A (88 ± 218ml, 83 ± 165ml). Systolic blood pressure just after CPB was higher in group B (67.9 ± 9.1mmHg) than in group A (55.4 ± 10.3mmHg). Postoperative ventilatory support was shorter in group B (45 ± 19h) than in group A (68 ± 27h). In neonatal cardiac surgery, low-priming-volume CPB circuits and DUF improve the water balance during surgery and may attenuate any inflammatory reaction, which would help preserve postoperative organ function.     

Zur flammenphotometrischen Calciumbestimmung im Urin

Zusammenfassung Für die Calciumbestimmung im Urin wird eine einfache und rasche flammenphotometrische Methode ohne vorherige Fällung des Calciums beschrieben. Der Kationenfehler kann dabei durch das Korrekturverfahren weitgehend ausgeschaltet werden, der Phosphat- und Sulfatfehler durch das Parallelverfahren, während der Bicarbonatfehler infolge Ansäuerung entfällt.Der mittlere Gesamtfehler der Methode beträgt etwa ± 7% (± 2).     

Freeze-fracture study of the mechanoreceptive digital corpuscles of mice

Summary The freeze-fracture replication technique was used to study the mechanoreceptive digital corpuscles in toe pads of mice. The axon terminal plasmalemma had intramembranous particles (IMPs) at a density of 2367 ± 517 m^–2 (mean ±s.e.m.) in the P-face and 84 ± 4 m^–2 in the E-face. Particles were 10 ± 1.8 nm in diameter in the P-face and 10 ± 1.5 nm (mean ±s.d.) in the E-face. Particle-rich and particle-free areas were noted in the P-face. The lamellar cell plasmalemma had IMPs at a density of 3359 ± 224 m^–2 in the P-face and 265 ± 95 m^–2 in the E-face. Particles were 10 ± 1.4 nm in diameter in the P-face and 10 ± 1.6 nm in the E-face. Non-terminal unmyelinated fibres in the connective tissue compartment of toe pads were also examined: the P-faces of the axolemma and Schwann cell plasmalemma had IMPs at a density of 1356 ± 283 m^–2 and 1514 ± 514 m^–2, respectively, while the E-face of these membranes had only a few particles. Particles were 9 ± 1.2 nm and 10 ± 1.6 nm in diameter in the P-faces of axon and Schwann cell plasmalemmata, respectively.The results show that the IMPs in terminal axolemma and in lamellar cell plasmalemma have a much higher density than those of non-terminal axons or Schwann cells in myelinated and unmyelinated fibres. In addition, IMPs in the terminal axolemma are larger than those in non-terminal axolemma except for the nodal axolemma. It can be said that plasmalemmata of both the axon terminals and lamellar cells of digital corpuscles are specialized in terms of IMPs, suggesting that they have specific physiological properties in mechanoreceptive functions including mechano-electric transduction.     

Disinhibition of hippocampal pyramidal cells during the transition into theta rhythm

The activity of hippocampal complex-spike cells (presumed pyramidal cells) and theta cells (presumed interneurons) was examined during transitions from non-theta electroencephalogram (EEG) states to theta EEG states in freely moving and sleeping rats. Theta cell firing rates were significantly depressed in a 1-s period centered on the EEG transition relative to the surrounding 1-s periods (normalized rates±SEM): 1.05±0.02 for the non-theta period, 0.59±0.03 for the transition period, and 1.36±0.04 for the theta period (n = 26 cells). Conversely, complex-spike cell firing was significantly increased during the transition period: 0.51±0.11 for the non-theta period, 2.24±0.19 for the transition period, and 0.24±0.04 for the theta period (n = 27 cells). This diametrically altered activity indicates that theta cells must be actively inhibited during the transition. The increased activity in complex-spike cells during the transition may be simply a release from inhibitory control by interneurons. The pattern of theta cell inhibition together with increased complex-spike cell activity appears to be a general property of transitions into the theta EEG state, irrespective of behavior. It is suggested that increased activity in septal afferents (GABAergic cell activity greater than cholinergic cell activity) initially inhibits hippocampal interneurons. The inhibition is not sustained because of an activity-dependent decrease in the potency of the septointerneuronal inhibition, leaving the rhythmic excitatory (cholinergic) septointerneuronal inputs, together with principal cell inputs, to increase interneuron firing rates.     

The AC impedance of necturus gallbladder epithelium

The impedance of Necturus gallbladder epithelium was determined using sine wave currents of 1 Hz to 30 kHz. In control Ringer's solution the impedance locus exhibited a simple semicircle with minute shift of the high frequency end along the real axis and a minute depression of the center below the real axis (average 0.9±0.7°). Neglecting the slight suppression, the impedance of 1 cm² of epithelium can be represented by an electrical analogue consisting of a parallel RC element of 115±26 and 5.16±0.9 F in series with a small resistor of 5.3±1.3. In agreement with experimental results obtained under ionic or osmotic substitutions, the applicability of this simple RC analogue to gallbladder epithelium under control conditions can be explained by the influence of the paracellular shunt and by assuming the time constants of the apical and basal cell membranes to be comparable. Based on these data and on voltage divider measurements obtained with microelectrodes the capacitances of the apical and basal cell membrane can be estimated to be 7 and 18 F/cm². The latter value agrees well with estimates of the surface folding obtained from electronmicrographs, if the specific cell membrane capacitance is assumed to be 1 F/cm² as in other cell membranes.     

Stimulus-specific patterns of myosin light chain phosphorylation in smooth muscle of rabbit thoracic artery

When the rabbit thoracic artery was stimulated with submaximal concentrations of agonist [40 mM K⁺, 30 M prostaglandin F₂ (PGF₂) or 7 M histamine], about 90% of a maximal contraction occurred. Each agonist induced a rapid development of contraction followed by a sustained response. The maximal rate of force generation stimulated with PGF₂ was twice that seen with K⁺ or histamine. Stimulation with 40 mM K⁺ increased the extent of monophosphorylated 20 kDa myosin light chain (MLC-P) for up to 1 min to a maximal value of 38.8±1.0%, there was a subsequent rapid decrease and the MLC-P level remained just above the basal value for 40 min (6.8±3.0%). In the case of stimulation with 7 M histamine, MLC-P level increased rapidly and was sustained for up to 40 min (28.0±4.9%). In contrast to the stimulation with K⁺ or histamine, PGF₂ induced both mono- and diphosphorylated MLC₂₀ (MLC-P and MLC-P 2 respectively) at a low concentration (3 M). The monophosphorylation of MLC₂₀ induced by 30 M PGF₂ reached the maximal value of 32.8±5.2%, and was sustained for up to 40 min (15.2±5.4%). The diphosphorylation of MLC₂₀ increased rapidly (7.4±4.0% at 5 min), then decreased to the basal value within 40 min. These results suggest that different modes of stimulation of smooth muscle contraction produce different profiles of MLC₂₀ phosphorylation. The implications of these observations are that the diphosphorylated form, specifically induced by certain agents, may modify the mode of contraction of the aortic artery.     

Time constants of facilitation and depression in Renshaw cell responses to random stimulation of motor axons

Summary In 9 adult anaesthetized cats, 22 lumbosacral Renshaw cells recorded with NaCl-filled micropipettes were activated by random stimulation of ventral roots or peripheral nerves. The stimulus patterns had mean rates of 9.5–13 or 20–23 or 45 pulses per second and were pseudo-Poisson; short intervals below ca. 5 ms (except in two cases) were excluded. The Renshaw cell responses were evaluated by two kinds of peristimulus-time histograms (PSTHs). Conventional PSTHs were calculated by averaging the Renshaw cell discharge with respect to all the stimuli in a train. These PSTHs showed an early excitatory response which was often followed by a longer-lasting slight reduction of the discharge probability. These two response components were positively correlated. Conditional PSTHs were determined by averaging the Renshaw cell discharge with respect to the second (test) stimulus in pairs of stimuli which were separated by varied intervals, . The direct effect of the first conditional response was subtracted from the excitation following the second (test) stimulus so as to isolate the effect caused by the second stimulus per se. After such a correction, the effect of the first conditioning stimulus showed pure depression, pure facilitation or mixed facilitation/depression. Analysis of such conditioning curves yielded two time constants of facilitation (ranges: ca. 4–35 ms and 93–102 ms) and two of depression (ranges: ca. 7–25 ms and 50–161 ms). It is concluded that these time constants are compatible with processes of short-term synaptic plasticity known from other synapses. Other processes such as afterhyperpolarization and mutual inhibition probably are of less importance.     

Binocular interactions and disparity coding in area 21a of cat extrastriate visual cortex

We have examined, using both qualitative and quantitative techniques, binocular interactions of extracellularly recorded single neurons in the extrastriate cortical area 21a of anaesthetized and paralysed cats. Consistent with previous reports we have found that: (a) all area 21a neurons were orientation-selective, with about 65% of them preferring orientations within 30° of the vertical; and (b) over 75% of area 21a cells could be activated through either eye. Furthermore, a significant minority (4 cells; about 10%) of a subpopulation of 39 neurons in which binocular interactions were examined quantitatively, were obligatory binocular neurons, that is, they responded very weakly, if at all, to the monocular stimuli presented through either eye but responded vigorously to simultaneous stimulation through both eyes. Almost 70% (27/39) of neurons tested quantitatively for binocular interaction have shown significant modulation (over 50%) of their peak responses in relation to binocular positional retinal disparities. The majority of neurons sensitive to binocular positional disparities resembled either tuned excitatory (22 cells; 56.5% of the sample) or tuned inhibitory (2 cells; 5% of our sample) cells. In particular, they gave, respectively, maximal or minimal responses to optimally oriented, moving photic stimuli when the receptive fields plotted through each eye completely or partially overlapped. Although neurons recorded in area 21a have relatively large receptive fields (mean width 3.3±1.1°; range 2.0–5.6°), the mean width of the disparity tuning curve (2.8±1.0°; range 1.3–4.8°) for our sample of area 21a neurons was similar to those of neurons with significantly smaller receptive fields, recorded in areas 17 and 18 of cat's primary visual cortex. We conclude that area 21a of the cat, like areas 17 and 18 of primary visual cortex, is likely to play an important role in binocular depth discrimination and might constitute a higher order area for stereoscopic binocular vision.     

Evidence for the presence of pro-γ-melanotropin,the NH2-terminal fragment of the corticotropin-β-lipotropin precursor,in corticotropin-producing tumours

Summary Five corticotropin-producing tumours were examined for peptides related to the corticotropin--lipotropin precursor. Two were basophil pituitary adenomas and three were bronchial carcinoids. The cells of the two pituitary adenomas stained with antisera against -endorphin and against pro--melanotropin, the NH₂-terminal fragment of the corticotropin--lipotropin precursor, but not with antisera against -melanotropin or -lipotropin. The corticotropin-storing tumor cells of the bronchial carcinoids stained with antisera against -endorphin, -lipotropin or pro--melanotropin. Only one of the three bronchial carcinoids contained cells reacting with the antiserum against -melanotropin. Although the two types of corticotropin-storing tumours (pituitary adenoma and bronchial carcinoid) differed with respect to -lipotropin content, the over-all picture indicates that the proteolytic processing of the corticotropin precursor proceeds along similar lines in tumour cells and in pituitary corticotrophs.An acetic acid extract of one of the bronchial tumours was subjected to gel chromatography and immunochemical analysis of material related to pro--melanotropin. The immunoreactive material displayed a considerable size heterogeneity, with the predominant components having a molecular weight larger than that of authentic pro--melanotropin.     

Effects of sleep deprivation on the activity of selected metabolic enzymes in skeletal muscle

Summary The present study gives the results of a comparison of the recorded and true tibia-calcaneal angles in 17 normal subjects and in 14 patients with abnormally hypoextensible non contracting triceps. 1. For a minimal passive torque, the difference between true and recorded angles varied considerably from one individual to another. The means and ranges for the two groups were respectively: –8 (+7, –21) and –7 (+5, –20). 2. When the passive torque increased as a result of slow passive lengthening of the muscle, the true curve was steeper than the recorded one, owing to differences between the two angle measurements. For each of the two groups the differences in means and ranges were respectively: 6 (0, +13.5) and 8 (3, 12). 3. Subjects made isometric voluntary contractions of the triceps surae at fixed angles which corresponded to step by step muscle lengthening. The resulting true curve was much steeper than the recorded curve. The differences in means and ranges were: 7 (1.5, +15) in children of the two groups and respectively 3 (0, +9) and 12 (10, 14) in adults of the two groups. The present results show that this methodology was the only reliable way of correctly obtaining passive and active torque-angle curves, measuring differences between subjects, appreciating the effects of treatments and these by ascertaining whether or not trophic muscle regulation was defective.     

Facilitation by 5-hydroxytryptamine of ATP-activated current in rat pheochromocytoma cells

The effects of 5-hydroxytryptamine (5-HT) on an inward current activated by extracellular ATP were investigated in rat pheochromocytoma PC12 cells. Under whole-cell voltage-clamp conditions 5-HT (10 M) reversibly enhanced the amplitude of the current activated by 30 M ATP. The enhancement may not be due to an increase in the number of functional channels because the current activated by 300 M ATP was not remarkably augmented compared with the current activated by 30 M ATP. The current enhancement by 100 M 5-HT was less obvious than that by 10 M 5-HT. When the current kinetics were compared, activation of the ATP-evoked current was accelerated to the same extent by either 10 or 100 M 5-HT, whereas deactivation was largely more accelerated by 100 M 5-HT. Propranolol (10 M), a 5-HT₁ receptor antagonist, or LY53857 (10 M), a 5-HT₂ receptor antagonist, exerted an agonistic effect: the ATP-activated current was facilitated by these compounds. Metoclopramide (10 M), a 5-HT₃ receptor antagonist, neither facilitated the ATP-activated current, nor blocked the current facilitation by 5-HT. Guanosine 5-O-(2-thiodiphosphate) (GDP[S]) (2 mM), the non-hydrolysable analog of guanosine 5-triphosphate (GTP), or K-252a (2 M), a protein kinase inhibitor, did not affect the facilitation by 5-HT of the ATP-activated current when they were included in the intracellular solution. The ATP-activated current pre-facilitated by 10 M dopamine was not enhanced by 10 M 5-HT. Similarly, the pre-facilitation by 5-HT attenuated the current enhancement by dopamine. The results suggest that 5-HT facilitates the ATP-activated channels through receptors that are not readily classified into conventional subclasses of 5-HT receptors. The reciprocal masking between the current facilitation by 5-HT and that by dopamine, combined with their sensitivities to the compounds involved in the intracellular solution, indicates that the facilitation by 5-HT may share not all, but some, common cellular mechanism with that by dopamine.     

Effect of inhibitors of cyclic nucleotide phosphodiesterases on electrical and contractile activity of smooth muscle cells

Double sucrose gap experiments were carried out to study the effect of phosphodiesterase inhibitors and penetrating analogs of cyclic nucleotides on action potential and contraction of guinea pig ureteral smooth muscle cells. 3-Isobutyl-1-methylxanthine (10 M) and dibutyryl-cAMP (20 M) shortened the plateau of action potential and inhibited contraction of smooth muscle cells by increasing potassium permeability of their membrane. Vinpocetine (1 M) and dibutyryl-cAMP (100 M) strengthened contraction of smooth muscle cells and shortened action potentials by decreasing sodium permeability of their membrane.     

On the terms “reticulosis” and “reticulum cell sarcoma” with regard to the modern concept of the monocyte macrophage system

Summary The terms reticulosis and reticulum cell sarcoma (= malignant lymphoma, histiocytic type) are discussed regarding the modern concept of the monocyte macrophage system which today has replaced the ancient theory of the reticuloendothelial system. The monocyte macrophage system is not independent, but closely related to the myeloid system. Thus, a third blood forming system as was believed in the case of RES does not exist. Phagocytic reticulum cells of the various hematopoietic organs are highly activated monocyte-derived macrophages. All those conditions formerly termed reticuloses have been found to belong either to the myeloid or to the lymphatic system. Considering the reticulum cell sarcomas or malignant histiocytic lymphomas, most of them seem to be of lymphatic rather than of macrophage origin, representing highgrade malignant lymphomas, possibly immunoblastic sarcomas. No relationship between these tumours and the monocyte macrophage system has been established, so far. Therefore, the terms reticulosis and reticulum cell sarcoma should be no longer used in order to avoid confusion, in order to stimulate sufficient diagnostic efforts which will really clarify such cases, and in order to give full credit to modern results of hematopathology.     

Die optische Rotationsdispersion isolierter Paraproteine

Zusammenfassung Die aus dem optischen Drehungsvermögen abgeleiteten Konstanten elektrophoretisch isolierterA-Paraproteine werden mitgeteilt. Die Dispersionskonstante _c weist keine Unterschiede zwischen den 3 ParaproteingruppenG,A undM auf. Der nach dem Verfahren vonMoffitt undYang ermittelte Parameterb ₀ wurde zu Schätzung des-Helixgehaltes benutzt. Er betrug in den 7 untersuchten Paraproteinen 0. Für den Parameter —a ₀ ergab sich ein Mittelwert von 276,0±35,1. FürG-Paraprotein wurde in früheren Untersuchungen ein solcher von 312,8±20,8, fürM-Paraprotein 217,9±26,7 gefunden. Der Mittelwertsvergleich zeigte Signifikanz der Konstantea ₀ für jede der 3 Paraproteingruppen.a ₀ beschreibt demnach gruppenspezifische Eigenschaften von Paraproteinen. Die für den Wert vona ₀ maßgeblichen strukturellen Voraussetzungen sind kaum bekannt. Sie werden am ehesten die die spezifischen Antigendeterminanten tragenden H-Ketten des Paraproteinmoleküls betreffen.

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Summary The constants of the optical rotatory dispersion of electrophoretically isolatedA-paraproteins are communicated. There is no difference between theG,A andM-paraprotein group with respect to the dispersion constant _c . The parameterb ₀ was measured according toMoffitt andYang. The-Helix-content calculated fromb ₀ of 7A-paraproteins was sero (0).The mean value of the parameter —a ₀ was 276±35,1. In earlier experiments it was found that —a ₀ forG-paraproteins is 312,8±20,8 and forM-paraproteins 217,9±26,7. The parametera ₀ of each group differs significantly from the others; in other words,a ₀ is group specific. The structural implications of these findings are discussed.

     

Stromal remodeling and SPARC (secreted protein acid rich in cysteine) expression in invasive ductal carcinomas of the breast

In the present study, we analyzed tumor associated stromal remodeling with special respect to SPARC (secreted protein acid rich in cysteine) expression. 25 invasive ductal carcinomas of the breast and corresponding tumor-free breast tissue were studied immunohistochemically (CD34, -SMA, SPARC and TGF-R1). Tumor associated stroma was characterized by a loss of CD34 expression, paralleled by a gain in -SMA. While SPARC expression was virtually absent from normal stromal cells in the tumor stroma, strong cytoplasmic SPARC reactivity was found in the majority of stromal cells. The TGF-R1 also showed stronger expression in the tumor stroma compared to that of the normal breast. Stromal response to antecedent core needle biopsy was similar to that observed in the tumor stroma. We conclude that SPARC overexpression is a constant and functionally important feature of invasive ductal carcinomas, since SPARC mediates stromal de-adhesion crucial for local tumor invasion and systemic spread, respectively. When considering changes of the stromal phenotype (normal: CD34⁺-SMA^–SPARC^– vs. carcinoma: CD34^–-SMA⁺SPARC⁺) as a tool in distinguishing benign from malignant breast lesion one has to keep in mind that the phenotype of granulation tissue in areas of antecedent biopsy resembles that of tumor stroma.     

Characterization of two components of the N-like,high-threshold-activated calcium channel current in differentiated SH-SY5Y cells

Retinoic acid differentiated SH-SY5Y cells exhibit only a high-threshold-activated (–30 to –20 mV) whole cell calcium channel current. When barium was used as the charge carrier, the high-threshold-activated current showed bi-exponential inactivation kinetics during a 500 ms voltage step from –90 to +10mV. The time constants of inactivation were approximately 75 and 750 ms. The fast inactivating component was more sensitive than the slow inactivating component to steady-state inactivation at depolarized holding potentials. The calcium channel current was inhibited by externally applied cadmium (10–300 M) and gadolinium (10–30 M) as well as by high concentrations of nickel and cobalt, Conus toxin (1 M) irreversibly blocked the calcium channel current. However, the dihydropyridine agonist, BAY K 8644 (3–10 M) and antagonists, nifedipine (3–10 M) and nimodipine (10 M) did not affect either component of the calcium channel current. Agents which blocked the calcium channel current did not exhibit any selectivity for the fast inactivating over the slow inactivating component of the current. These results indicate that whilst the calcium channel current recorded in differentiated SH-SY5Y cells can be classified on the basis of the blocking agents as being of the N type, the current shows more than one form of inactivation.     

Skull radiograph measurements of normals and patients with basilar impression; use of Landzert's angle

Summary One hundred normal lateral skull radiographs were studied and those of ten patients with basilar impression attending Kenyatta Hospital, Nairobi. The mean shortest distance of the odontoid tip to McGregor's basal line was 1.2±2.28 mm below the basal line (range 6 mm below to 3 mm above basal line), in normals and 9±2.7 mm (6–14 mm) above basal line in patients. The mean basal angle was 113±7 (102–133) in normals and 122±6 (113–125) in patients. The mean nasion-basion-opisthion angle was 162±4 (154–169) in normals and 178±5 (173–185) in patients. The mean total length of clivus was 48±3.7 mm (43–56 mm) in normals and 44±6.6 (36–48 mm) in patients group. The mean median diameter of the foramen magnum was 39±5 mm (30–48 mm), atlas 21±3 mm (18–25 mm) axis 18±3 mm (14–23 mm), third cervical vertebra 16±2 mm (13–22 mm) in normals and in patients: 39±4 mm (36–45 mm), atlas 23±6 (l5–30 mm) axis 19±4 mm (16–25 mm), third cervical vertebra 16±3 (14–20). There was a significant difference in the position of the odontoid tip and the nasion-basion-opisthion angle between the normal and patient groups. All the other parameters measured in this work did not differ significantly between the two groups.

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Etude anatomo-radiologique de crânes normaux et de crânes pathologiques avec impression basilaire; utilisation de l'angle de Landzert

Résumé Cent crânes normaux ont été étudiés sur des radiographies de profil ainsi que dix crânes pathologiques présentant des impressions basilaires chez des patients traités à l'HÔpital Kenyatta de Nairobi. La plus courte distance moyenne entre le sommet de l'odontoÏde et la ligne basale de McGregor a été de 1,2±2,28 mm au-dessous de la ligne basale (extrÊmes étendues de 6 mm au-dessous à 3 mm au-dessus de la ligne basale), chez les sujets normaux et de 9±2,7 mm (6–14 mm) au-dessus de la ligne basale chez les sujets pathologiques. L'angle basai moyen était de 113±7 (102–133) chez les sujets normaux et 122±6 (113–125) chez les sujets pathologiques. L'angle moyen nasion-basion-opisthion était de 162±4 (154–169) chez les sujets normaux et 178±5 (173–185) chez les sujets pathologiques. La longueur moyenne totale du clivus était de 48±3,7 mm (43–56 mm) chez les sujets normaux et 44±6,6 (36–48 mm) chez les sujets pathologiques. Le diamètre moyen du foramen magnum était de 39±5 mm (30–48 mm), celui du foramen vertébral de l'atlas était de 21±3 mm (18 à 25 mm), celui de l'axis (18±3 mm (14–23 mm), celui de la troisième vertèbre cervicale: 16±3 mm (13–22 mm) chez les sujets normaux; chez les sujets pathologiques les chiffres étaient les suivants: foramen magnum 39±4 mm (39–45 mm), atlas 23±6 (15–30 mm), axis 19±4 mm (16–25 mm), troisième vertèbre cervicale 16±3 mm (14–20 mm). Il existe une différence significative dans la position du sommet de l'odontoÏde et la valeur de l'angle nasion-basion-opisthion entre les deux groupes. Aucun des autres paramètres mesurés dans ce travail ne présentait de différence significative entre les deux groupes.

     

Redistribution of Schwann cells in developing feline L7 ventral spinal roots

Summary The length and distribution of Schwann cells along fibres in the ventral root L7 of the developing cat have been studied electron microscopically in serial sections. The average Schwann cell length at the beginning of myelin formation — the initial internodal length — was 118 m (110 m in -axons and 124 m in -axons). The number of Schwann cells found in a fully developed root segment was already present at the beginning of the myelination. It showed no systematic age-dependent variation from the beginning of myelination to adulthood. The Schwann cells associated with -axons increased their length 12.6 times during this period, while the root elongated 5.6 times. About 50% of the Schwann cells had to be eliminated in order to make the elongation of the remaining Schwann cells possible. Corresponding calculations from the mean length of Schwann cells associated with -axons, showed that about 50% too few Schwann cells were associated with the -axons during the period of initial myelination of the -axons. At birth, when the myelination of -axons had just begun, both the large surplus along -axons and the deficit along -axons had disappeared. We suggest that Schwann cells are eliminated from the -axons and re-utilized along the -axons. During this process of cellular redistribution, affected cells constitute so-called aberrant Schwann cells.