Preferential orientation of centrioles toward the heart in endothelial cells of major blood vessels is reestablished after reversal of a segment.
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The distribution of centrioles was examined in porcine and rabbit vascular endothelial cells fixed in situ and prepared en face for immunofluorescent staining with rabbit sera that specifically stain these organelles. In endothelial cells lining the major blood vessels of the pig, the centrioles are preferentially located on the heart side of the nucleus regardless of the direction of blood flow. A similar distribution is seen in the inferior vena cava of the rabbit but not in the rabbit aorta. In the major vessels of the pig and in the rabbit inferior vena cava, 60%-80% of the endothelial cells have their centrioles located on the side of the nucleus toward the heart, 10%-20% have them on the side away from the heart, and 7%-15% have them in a central position along the side of the nucleus. To determine whether this preferential orientation is reestablished, microvascular surgical techniques were used to reverse a 3-cm segment of the inferior vena cava between the left renal vein and the common iliac veins of the rabbit. Within 1 week of the reversal, some of the centrioles had migrated from the end away from the heart to a more central position. During the following weeks, an increasing number of endothelial cells had their centrioles located on the heart side of the nucleus; after 12 weeks, values similar to those in the nonreversed inferior vena cava were reached in the reversed segment. The demonstration that the preferential orientation of centrioles on the heart side of the nucleus is reestablished after reversal of a segment suggests that the observed polarity is important for normal functioning of vascular endothelium.Keywords:
Centriole
Venae cavae
In 231 cases the frequency of double inferior Cava in postrenal part is determined at 0.5%. The importance of double inferior Cava is discussed. This variation is the most frequent of V. cava inferior. The genesis is by persistence of left sacro-cardinal-vein (supracardinal-vein) over the six embryonical week. The casus, here mentioned, has an anastomosis overmore. This anastomosis cross Aorta and A. mesenterica inferior ventral, combines both inferior Cavae and must be interpreted as a second inferior Anastomosis intersubcardinalis.
Venae cavae
Vena cava
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Newly formed centrioles in cycling cells undergo a maturation process that is almost two cell cycles long before they become competent to function as microtubule-organizing centers and basal bodies. As a result, each cell contains three generations of centrioles, only one of which is able to form cilia. It is not known how this long and complex process is regulated. We show that controlled Plk1 activity is required for gradual biochemical and structural maturation of the centrioles and timely appendage assembly. Inhibition of Plk1 impeded accumulation of appendage proteins and appendage formation. Unscheduled Plk1 activity, either in cycling or interphase-arrested cells, accelerated centriole maturation and appendage and cilia formation on the nascent centrioles, erasing the age difference between centrioles in one cell. These findings provide a new understanding of how the centriole cycle is regulated and how proper cilia and centrosome numbers are maintained in the cells.
Centriole
Basal body
PLK1
Interphase
Spindle pole body
Centrosome cycle
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The patient is a 42 year old female. She is a chronic carrier of hepatitis B virus and is on regular follow up for the same. The computed tomography was done to look for a suspicious area in the liver, detected on a routine ultrasound of the abdomen. The liver examination was normal. Incidentally, a congenital anomaly of the inferior vena cava was detected. The two common iliac veins failed to unite at the level of the aortic bifurcation. The two venae cavae ascend on both sides of the aorta. The left inferior vena cava drains into the left renal vein. The left renal vein crosses anterior to the aorta to form the normal right prerenal inferior vena cava. The prevalence of this anomaly is 0.2%–3%.1 This arrangement of the left renal vein crossing anterior to the inferior vena cava to form normal right prerenal inferior vena cava is the commonest arrangement in the duplication of inferior vena cava.1
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The Cep63-Cep152 complex located at the mother centriole recruits Plk4 to initiate centriole biogenesis. How the complex is targeted to mother centrioles, however, is unclear. In this study, we show that Cep57 and its paralog, Cep57l1, colocalize with Cep63 and Cep152 at the proximal end of mother centrioles in both cycling cells and multiciliated cells undergoing centriole amplification. Both Cep57 and Cep57l1 bind to the centrosomal targeting region of Cep63. The depletion of both proteins, but not either one, blocks loading of the Cep63-Cep152 complex to mother centrioles and consequently prevents centriole duplication. We propose that Cep57 and Cep57l1 function redundantly to ensure recruitment of the Cep63-Cep152 complex to the mother centrioles for procentriole formation.
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Centrioles are precisely built microtubule-based structures that assemble centrosomes and cilia. Aberrations in centriole structure are common in tumors, yet how these aberrations arise is unknown. Analysis of centriole structure is difficult because it requires demanding electron microscopy. Here we employ expansion microscopy to study the origins of centriole structural aberrations in large populations of human cells. We discover that centrioles do not have an elongation monitoring mechanism, which renders them prone to over-elongation, especially during prolonged mitosis induced by various factors, importantly including supernumerary centrioles. We identify that mitotic centriole over-elongation is dependent on mitotic Polo-like kinase 1, which we uncover as a novel regulator of centriole elongation in human cycling cells. While insufficient Plk1 levels lead to the formation of shorter centrioles lacking a full set of microtubule triplets, its overactivity results in over-elongated and structurally aberrant centrioles. Our data help explain the origin of structurally aberrant centrioles and why centriole numerical and structural defects coexist in tumors.
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PLK1
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1. Thermo‐electric observations of temperature distribution in the ‘core’ area of monkeys and baboons are reported. 2. Temperature gradients were shown to exist in the inferior vena cava, temperatures rising by a mean value of 0·2° C at the entry of the renal veins and again by a further 0·2° C at the level of the hepatic veins. 3. Temperatures in the right atrium were on average 0·1° C lower than in the inferior vena cava due to the return of relatively cooler blood from the superior vena cava. 4. Net heat exchanges in the thorax were small. Right atrial and aortic blood temperatures were not significantly different and it was concluded that heat losses in the thorax were balanced by heat production in lungs and heart. 5. The mean liver temperature was 0·1° C higher than that of the aortic blood irrespective of the environment. 6. The mean temperature recorded from the lumen of the jejunum was 0·2° C warmer than the aorta in the ‘warm’ environment and 0·4° C hotter than the aorta in the ‘cool’ environment. In both environments intrajejunal temperature was higher than the liver but the differential was increased by exposure to a ‘cool’ environment. 7. Evidence is adduced to suggest that the gastro‐intestinal tract in the body at rest is a major heat producer contributing about double the amount of heat generated by the liver. 8. It is suggested that blood flow redistribution in the splanchnic area on exposure of the body to cold is the main cause of the change in aortic—jejunal and jejunal—liver differentials. Metabolic factors have, however, not been excluded.
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Abstract Cep152 and Cep63 act as the cradle and recruit Plk4 to initiate the centriole biogenesis in a mother centriole dependent manner. However, how the Cep152-Cep63 complex is targeted to the proximal end of mother centrioles is unclear. In this study, we show that Cep57 and its paralog, Cep57l1, colocalize with Cep63 and Cep152 at the proximal end of mother centrioles in both cycling cells and differentiated multiciliated cells. Both Cep57 and Cep57l1 associate with the Cep152-Cep63 complex by directly binding to the centrosomal targeting region of Cep63. Co-depletion of Cep57 and Cep57l1 blocks the loading of Cep63-Cep152 to the centriole and subsequently prevents centriole duplication. We propose that Cep57 and Cep57l1 act together to ensure the recruitment of the Cep63-Cep152 complex to the mother centrioles for procentriole formation. Summary statement Cep57 and its paralog, Cep57l1, cooperatively act as a molecular scaffold to recruit the Cep63-Cep152 cradle to the proximal end of centrioles in the early stages of centriole duplication.
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In sixty normal adult livers the retrohepatic segment of the inferior vena cava was found mostly to assume a curve to the left (75.00%). This segment has a length of 7.1 cm and is totally encircled by liver substance in 6.67% of cases. Altogether 492 ostia venae hepaticae were studied, averaging 8.2 per liver and classified as large, medium and small. The large ostia are divided into superior (SLO) and inferior (ILO) openings. The SLO are found opening into the upper end of the hepatic segment of the inferior vena cava, frequently with part of the venous walls exposed outside the liver. The ILO and medium ostia are present in 95% of the livers, appearing mainly on the lower quarter of the right half of the wall of the retrohepatic segment of the inferior vena cava as well as on the left anterior wall of that segment. The ILO may serve as the exit for several hepatic veins and they may be multiple. Their significance in respect of liver surgery is discussed.
Human liver
Vena cava
Venae cavae
Hepatic veins
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Vertebrate centrioles lose their geometric scaffold, the cartwheel, during mitosis, concurrently with gaining the ability to recruit the pericentriolar material (PCM) and thereby function as the centrosome. Cartwheel removal has recently been implicated in centriole duplication, but whether "cartwheel-less" centrioles are intrinsically stable or must be maintained through other modifications remains unclear. Here, we identify a newborn centriole-enriched protein, KIAA1731/CEP295, specifically mediating centriole-to-centrosome conversion but dispensable for cartwheel removal. In the absence of CEP295, centrioles form in the S/G2 phase and lose their associated cartwheel in mitosis but cannot be converted to centrosomes, uncoupling the two events. Strikingly, centrioles devoid of both the PCM and the cartwheel progressively lose centriolar components, whereas centrioles associating with either the cartwheel or PCM alone can exist stably. Thus, cartwheel removal can have grave repercussions to centriole stability, and centriole-to-centrosome conversion mediated by CEP295 must occur in parallel to maintain cartwheel-less centrioles for duplication.
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Ventilatory effect on inferior vena caval configuration was studied by ultrasonography in 14 subjects, including 5 with chronic obstructive pulmonary disease, 3 with cardiac tamponade due to carcinomatous pericardial effusion, one with tuberculous constrictive pericarditis, and 5 normal subjects. The inferior vena caval lumen decreased in the early inspiratory phase, reached a minimum at the end of inspiration, distended again during expiration, and closed transiently 2 to 3 cm below the diaphragm during maximal inspiration. These ventilatory changes of the inferior vena cava reversed with increase in intrathoracic pressure during the Valsalva maneuver and positive-pressure ventilation. When the central venous pressure was increased, as in cardiac tamponade, the inferior vena cava was fully distended through the entire phase of inspiration and expiration. Collapsibility of the inferior vena cava was inversely proportional to central venous pressure when the pressure was less than 10 cm H2O, but not when the pressure was greater than approximately 10 cm H2O. Our results suggest that the study of inferior vena caval configuration with ultrasonogrphy is a valuable noninvasive clinical aid for estimating central venous pressure and for analyzing inferior vena caval hemodynamics in various clinical conditions.
Expiration
Venae cavae
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