Elephants Have Relatively the Largest Cerebellum Size of Mammals

The current study used MR imaging to determine the volume of the cerebellum and its component parts in the brain of three adult male African elephants (Loxodonta africana) and compared this with published data from Asian elephants and other mammalian species including odontocete cetaceans, primates, chiropterans, insectivores, carnivores, and artiodactyls. The cerebellum of the adult elephant has a volume of ～925 mL (average of both African and Asian species). Allometric analysis indicates that the elephant has the largest relative cerebellum size of all mammals studied to date. In addition, both odontocete cetaceans and microchiropterans appear to have large relative cerebellar sizes. The vermal and hemispheric components of the African elephant cerebellum are both large relative to other mammals of similar brain size, however, for odontocete cetaceans the vermal component is small and the hemispheric component is large. These volumetric observations are related to life‐histories and anatomies of the species investigated. The current study provides context for one aspect of the elephant brain in the broader picture of mammalian brain evolution. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.     

Brain of the African elephant (Loxodonta africana): neuroanatomy from magnetic resonance images

We acquired magnetic resonance images of the brain of an adult African elephant, Loxodonta africana, in the axial and parasagittal planes and produced anatomically labeled images. We quantified the volume of the whole brain (3,886.7 cm3) and of the neocortical and cerebellar gray and white matter. The white matter-to-gray matter ratio in the elephant neocortex and cerebellum is in keeping with that expected for a brain of this size. The ratio of neocortical gray matter volume to corpus callosum cross-sectional area is similar in the elephant and human brains (108 and 93.7, respectively), emphasizing the difference between terrestrial mammals and cetaceans, which have a very small corpus callosum relative to the volume of neocortical gray matter (ratio of 181-287 in our sample). Finally, the elephant has an unusually large and convoluted hippocampus compared to primates and especially to cetaceans. This may be related to the extremely long social and chemical memory of elephants.     

Age-dependent brain temperature decline assessed by diffusion-weighted imaging thermometry

Brain metabolism declines with age, but cerebral blood flow (CBF) is less age dependent. We therefore hypothesized that the brain temperature would decline with age, and measured the temperatures of the lateral ventricles in healthy volunteers. Diffusion‐weighted imaging (DWI) data from 45 healthy volunteers [mean (± standard deviation) age, 30.6 ± 8.66 years; range, 19–56 years] were used for this study. The temperature of water molecules is directly related to the diffusion coefficient, so that the temperature of cerebrospinal fluid can be measured using DWI. Temperature was calculated using the equation, T ( °C) = 2256.74/ln(4.39221/D) – 273.15, where D is the diffusion coefficient. The lateral ventricles were manually extracted by an experienced neuroradiologist on b₀ images. The mean ventricular temperature was determined from the distribution function of the temperature of all selected voxels. The mean lateral ventricular temperature in healthy volunteers showed a linear decrease with age (correlation coefficient R² = 0.8879; p < 0.01), presumably caused by an asynchronous decline in brain metabolism and CBF. DWI‐based thermometry demonstrates that ventricular temperature declines with the normal aging process. Further study is warranted to define the relationships between temperature, metabolism and circulation. Copyright © 2011 John Wiley & Sons, Ltd.     

运用体视学方法有效地估测成人侧脑室容量

在１００例正常人的头颅ＣＴ扫描图像上运用体视学方法测定了测脑室容量，其中５０例同时运用ＣＴ部分容积分析法（ＰＶＡ法）测定了侧脑室的容量。经统计分析表明，（１）二种方法间的差异无显著性；（２）２０－５０岁期间侧脑室容量无显著性年龄差异，男、女间的差异也不显著；（３）２０－５０岁正常活体成人侧脑室容量平均为９．１ｍｌ，９５％正常值范围为４．８－１８．４ｍｌ。     

A Comparative Assessment of the Size of the Frontal Air Sinus in the Giraffe (Giraffa camelopardalis)

The current study examines the frontal air sinus of the giraffe (Giraffa camelopardalis) cranium with the aim of evaluating previously offered hypotheses as to why they have such an atypically voluminous frontal sinus relative to other artiodactyls. To date, no quantification of the frontal sinus in the adult or developing giraffe has been undertaken or compared to other artiodactyl species. Crania from eight species of adult artiodactyls, and giraffes varying in age from newborn to adult, were studied using CT scans to provide a volumetric assessment of the frontal sinus. Sinus volume was strongly correlated to cranial mass in the male giraffe ontogenetic series. The adult giraffe of both sexes were found to possess a far larger than predicted sinus volume relative to the relationship between frontal sinus volume and cranial mass observed in the other adult artiodactyls. Our results suggest that the volume of the frontal sinus in the giraffe is likely to be unique among artiodactyls, and the potential function and evolution we consider in light of several previously articulated hypotheses. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Mechanical pathophysiology of some heart diseases: a theoretical model study

Sarcomere dynamics are related to the global left ventricular (LV) function in some representative pathological states, by using a theoretical model which combines sarcomere function, LV fibrous structure and geometry with the haemodynamic loading conditions. The analysis shows that pressure (concentric) hypertrophy due to hypertension or aortic stenosis is associated with an increase of the normal endocardial-to-epicardial gradient(s) of oxygen demand, which may be one of the causes for the development of endocardial fibrosis. The analysis also indicates that sarcomere shortening is relatively normal in compensated volume (eccentric) hypertrophy. Mitral stenosis demonstrates a case of decreased LV function, secondary to a chronic decrease in LV end diastolic volume, with sarcomeres that operate at their lowest length range. Conversely, the sarcomere function is depressed in cardiomyopathy; the heart's pumping function is maintained by appropriate adjustment mechanisms. However, the sarcomeres show minimal shortening and function at their highest length range with low (or zero) functional reserve. The study thus provides a quantitative tool that relates global LV function to local sarcomere dynamics in various pathological states.     

Calculation methods for ventricular diffusion-weighted imaging thermometry: phantom and volunteer studies

A method for the measurement of temperature in the lateral ventricle using diffusion‐weighted imaging (DWI) has been proposed recently. This method uses predetermined arbitrary thresholds, but a more objective method of calculation would be useful. We therefore compared four different calculation methods, two of which were newly created and did not require predetermined thresholds. A rectangular polyethylene terephthalate bottle (8 × 10 × 28 cm³) was filled with heated water (35.0–38.8 °C) and used as a water phantom. The DWI data of 23 healthy subjects (aged 26–75 years; mean ± standard deviation, 50.13 ± 19.1 years) were used for this study. The temperature was calculated using the following equation: T(°C) = 2256.74/ln(4.39221/D) ? 273.15, where D is the diffusion coefficient. The mean ventricular temperature was calculated by four methods: two thresholding methods and two histogram curve‐fitting methods. As a reference, we used the temperature measured at the tympanic membrane, which is known to be approximately 1 °C lower than the brain temperature. The averaged differences in temperature between mercury thermometry and classical predetermined thresholding methods for the water phantom were 0.10 ± 0.42 and 0.05 ± 0.41 °C, respectively. The histogram curve‐fitting methods, however, yielded temperatures a little lower (averaged differences of ?0.24 ± 0.32 and ?0.14 ± 0.31 °C, respectively) than mercury thermometry. There was very little difference in temperature between tympanic thermometry and classical predetermined thresholding methods (+0.01 and ?0.07 °C, respectively). In humans, however, the histogram curve‐fitting methods yielded temperatures approximately 1 °C higher (+1.04 °C and +1.36 °C, respectively), suggesting that temperatures measured in this way more closely approximate the true brain temperature. The histogram curve‐fitting methods were more objective and better matched the estimated brain temperature than did classical predetermined thresholding methods, although the standard deviation was wider in the former methods. Copyright © 2011 John Wiley & Sons, Ltd.     

Experimental acute hypoxia in healthy subjects: evaluation of systolic and diastolic function of the left ventricle at rest and during exercise using echocardiography

To clarify whether or not systolic and diastolic function of the human left ventricle (LV) were decreased during acute hypoxia, at rest and with exercise, 14 healthy male volunteers [age 25.9 (SD 3.0) years, height 182.9 (SD 7.1) cm, body mass 75.9 (SD 6.9)kg] were examined using M-mode and 2D-mode echocardiography to determine the systolic LV function as well as Doppler-echocardiography for the assessment of diastolic LV function on 2 separate test days. In random order, the subjects breathed either air on 1 day (N) or a gas mixture with reduced oxygen content on the other (H; oxygen fraction in inspired gas 0.14). Measurements on either day were made at rest, several times during incremental cycle exercise in a supine position (6-min increments of 50 W, maximal load 150 W) and in 6th min of recovery. Corresponding measurements during N and H were compared statistically. Arterial O₂ tension (P _aO₂) was normal on N-day. All subjects showed a marked acute hypoxia at rest [P _aO₂, 54.5 (SD 4.6) mmHg], during exercise and recovery on H-day. The latter was associated with tachycardia compared to N-day. All echocardiographic measurements at rest were within the limits of normal values on both test days. Ejection time, end-systolic and end-diastolic left ventricular dimensions as well as the thickness of left posterior wall and of interventricular septum showed no statistically significant influence of H either at rest or during exercise. Stroke volume and cardiac output were always higher on H-day, which could be attributed to a slight reduction in end-systolic volume with unaffected end-diastolic volume as well as to increased heart rates. Among the indices of systolic LV function the fractions of thickening in the left ventricular posterior wall and interventricular septum showed no differences between H and N at rest or during exercise. However, fibre shortening, ejection fraction and mean circumferential fibre shortening were increased on H-day on all occasions. The mitral-valve-Doppler ratio, the index of diastolic LV function, was decreased with H at rest, showed a more pronounced reduction during exercise and was still lower in 6th min of recovery compared to N-day. It was concluded that with acute hypoxia of the severity applied in this study left ventricular systolic function in our healthy subjects showed a pronounced improvement and left ventricular diastolic function was reduced, both at rest and with exercise.     

Long and short axis dimensions of the left ventricle change in opposite ways during respiration

Cardiac output and stroke volume are known to vary with respiration. While right ventricular stroke volume increases on inspiration, left ventricular stroke volume decreases. This is an echocardiographic study of the changes in left ventricular dimensions in 20 healthy subjects. Our results show that the decrease in left ventricular stroke volume on inspiration is a net effect of a decrease in short axis shortening due to a decrease in diastolic diameter by 4.8% (P < 0.001) and an increased motion in the long axis direction expressed as an increase in mitral ring motion by 5.5% (P < 0.001). The findings point to the importance of the interventricular septum for the regulation of stroke volume.     

人体侧脑室容量年龄变化的研究

在１３５例正常人体头颅ＣＴ扫描图像上运用体视学方法研究了侧脑室容量的年龄变化。结果为：（１）侧脑室的容量随年龄的增长而逐渐增大，５０岁以后容量显著增大；（２）９月－１０岁组与１１－２０岁组之间，５１－６０岁组与６１－７０岁组之间，２１－５０岁期间侧脑室任人唯贤一无显著性差异；（３）９月－９０岁的蓁各年龄组之间的侧脑室容量均存在显著性差异。     

Effect of left ventricular shape alteration on contractility and function

We have investigated the effect of left ventricular (LV) shape on contractility and ejection function. In this study, a new contractility index is developed in terms of the wall stress (σ*, normalized with respect to LV pressure) by means of an LV ellipsoidal model. Using cine-ventriculography data, the LV ellipsoidal model (LVEM) major (B) and minor axes (A) are derived for the entire cardiac cycle. Thereafter, a new contractility index (CONT1) is derived as dσ*/dt, incorporating the LV ellipsoidal shape factor. Also, another contractility index (CONT2) was developed in terms of the generated σ* at the start of ejection phase, and maximized with respect to B/Ashape parameter, to obtain the optimal value of B/Aover the physiological ranges of the ratio of myocardial volume and LV volume. The in vivovalue of B/Aat the start of ejection is compared with this optimal value, and the LV contractility is evaluated in terms of the proximity of the in vivo B/Ato the optimal B/A. The results indicate that a non-optimal less-ellipsoidal shape (or more spherical) is associated with decreased contractility (and poor systolic function) of the LV, associated with a failing heart.     

Evidence of a hyperkinetic state in children with elevated blood pressure

Background: Left ventricular hypertrophy (LVH) and elevated left ventricular mass index (LVMI) are important predictors of cardiovascular morbidity and mortality in adults. Children with hypertension and pre-hypertension demonstrate LVH and greater LVMI compared to normotensive children. The impact of blood pressure (BP) on early changes in left ventricular properties provides an opportunity to understand and identify cardiovascular risk early in childhood.

Aim: The aim of this study was to assess left ventricular structural and functional properties in a sample of children across a wide range of BP values.

Subjects and methods: Children aged 11–14-years were divided into BP groups: hypertensives (HTN; ≥95th percentile; n?=?21) and normotensives (NTN; <90th percentile; n?=?85) based on BP measures taken at two time points. Resting supine heart rate (HR), cardiac output (CO) and total peripheral resistance (TPR) were collected along with left ventricular structural and functional properties using ultrasound sonography. Results: LVMI and TPR were not different between groups. CO, HR and left ventricular end-diastolic and end-systolic volumes were elevated in the HTN group. Furthermore, HR and body mass index were found to be independent predictors of BP group status in children.

Conclusion: These findings show that children with elevated BP are characterized by high HR and CO and normal TPR. Also, the results identify HR as a predictor of BP group status in early childhood.     

Morphological Study on Microvasculature of Left Ventricular Wall in Infant and Adult Yaks

Observations on the microvasculature in the left ventricular wall of infant and adult yaks under light and scanning electron microscope (SEM) were presented. Moreover, the diameter of different microvasculature and the density of the capillaries in three layers of the ventricular myocardium were measured using Image Pro‐Plus 5.0. The results showed that the average luminal diameter of arterioles and precapillary arterioles in adult yak's hearts were, in most cases, larger than those in infant yaks. On the contrary, the diameters of the capillary in infant yak's hearts were larger than those in adult yaks. The density of capillary in the myocardium of adult yak's heart had significantly higher values (P<0.01) than those in infant yaks. Arterioles of yak's hearts were characterized by the bark‐like structure and the impressions of endothelial cell nuclei, and it always gave rise to capillary after three to four grades of embranchment. The outer surface of capillaries cast in infant yak's hearts was smooth, and no constrictions were found. This was different from adult yak that always had some constrictions. The capillary anastomosis of “H” and “Y” usually existed in the myocardium of both adult and infant yaks; however, those in infant yaks were not typical as in adult yaks in their shape. The peculiar arrangement of the venules in infant yak was a “baggy” or “bulgy” arrangement, while in the adult yak, they had a root‐like pattern. Our findings suggest that the patterns of microvasculature in yak's heart could be propitious to adapt better in their environment following their increase of age. Anat Rec 293:1519–1526, 2010. © 2010 Wiley‐Liss, Inc.     

Microanatomy of Human Left Ventricular Coronary Veins

We describe analyses of the microanatomy of major left ventricular veins, including their relationship to the myocardium. Immediately following fixation of six fresh human hearts, anterior interventricular veins (AIV), left marginal veins (LMV), posterior veins of the left ventricle (PVLV), and posterior interventricular veins (PIV) were sectioned in ～5 mm intervals perpendicular to the veins' length from base to apex. Slides were prepared, digitized, and analyzed; measurements were made of each vein's wall thickness, circumference, distance between vein wall and myocardium, and distance between vein wall and closest artery. For analyses, based on the length of each vein, slides were grouped into three regions: basal (top third), mid (middle third), and apical (bottom third). Vein wall thicknesses and circumferences were significantly smaller (P < 0.05) in apical than basal regions in all veins. Vein wall thicknesses were significantly larger in the AIV and PIV than in the LMV and PVLV (P < 0.05). The AIV was significantly farther away (1.81–2.99 mm) from the myocardium than the other three veins (P < 0.05). Left ventricular venous microanatomy was quantified and analyzed. Variation in venous microanatomy, including distance between vein walls and excitable myocardium, could impact therapies involving the coronary venous system. Anat Rec, 2009. © 2008 Wiley‐Liss, Inc.     

大脑中线结构的断层解剖与三维重建研究

目的　对大脑中线结构进行三维重建、第三脑室体积测量分析,为第三脑室前中部肿瘤切除的手术方法提供解剖学依据。 方法　选取10例经福尔马林固定的成年大脑标本（男、女各5例）,经火棉胶包埋,分别制成厚500 μm 的水平位和冠状位火棉胶薄层切片,并对其进行观察、图像采集,选取其中一组女性水平位切片图像应用Amira软件进行三维重建,并对10例标本第三脑室进行体积测量。 结果　三维重建结果清晰显示了大脑中线结构胼胝体、穹窿、前连合、第三脑室、丘脑及丘脑间粘合的形态及毗邻关系,男性第三脑室平均体积为(1170.03±148.04) mm3,女性为(854.64±43.59)mm3,P>0.05,无统计学意义。 结论　对大脑中线结构的三维重建清晰的展示各个结构的立体形态和毗邻关系,为胼胝体-穹窿间手术入路切除第三脑室肿瘤提供了形态学依据,同时排除丘脑间粘合影响的第三脑室体积测量及男女体积差异性分析为脑室内镜手术操作空间提供了重要的参考价值。     

Assessment of Ventricular Contractility During Cardiac Magnetic Resonance Imaging Examinations Using Normalized Maximal Ventricular Power

Normalized maximal ventricular power (nPWR^max) is an index of cardiac function which measures the innate blood pumping ability, or contractility, of the left ventricle (LV), and its noninvasive assessment could prove useful in a variety of patients. nPWR^max is defined as the maximum instantaneous product of LV pressure and the rate of change of LV volume, divided by the end diastolic volume squared. We have quantified nPWR^maxnoninvasively in humans by pairing magnetic resonance imaging (MRI) LV volume measurements with aortic pressure estimated using radial artery tonometry and a frequency domain transfer function. In healthy volunteers undergoing cardiac MRI we have tested the sensitivity of nPWR^max to LV contractility with dobutamine and to cardiac loading with methoxamine, a vasoconstrictor. We have found that aortic pressures can be reliably estimated using a transfer function, which we generated and validated in a group of patients undergoing cardiac catheterization. Furthermore, we found that nPWR^max was unchanged by methoxamine, yet sensitive to contractility, with a 325% increase at dobutamine levels half that given during routine clinical cardiac stress tests for ischemia. In conclusion, we have shown that ventricular contractility can be assessed independent of cardiac loading in patients during routine noninvasive cardiac imaging examinations. © 2001 Biomedical Engineering Society. PAC01: 8761Pk, 8719Hh, 8719Uv     

Muscle�Ctendon structure and dimensions in adults and children

Muscle performance is closely related to the architecture and dimensions of the muscle–tendon unit and the effect of maturation on these architectural characteristics in humans is currently unknown. This study determined whether there are differences in musculo‐tendinous architecture between adults and children of both sexes. Fascicle length and pennation angle were measured from ultrasound images at three sites along the length of the vastus intermedius, vastus lateralis, vastis medialis and rectus femoris muscles. Muscle volume and muscle–tendon length were measured from magnetic resonance images. Muscle physiological cross‐sectional area (PCSA) was calculated as the ratio of muscle volume to optimum fascicle length. Fascicle length was greater in the adult groups than in children (P < 0.05) but pennation angle did not differ between groups (P > 0.05). The ratios between fascicle and muscle length and between fascicle and tendon length were not different (P > 0.05) between adults and children for any quadriceps muscle. Quadriceps volume and PCSA of each muscle were greater in adults than children (P < 0.01) but the relative proportion of each head to the total quadriceps volume was similar in all groups. However, the difference in PCSA between adults and children (men ～ 104% greater than boys, women ～ 57% greater than girls) was greater (P < 0.05) than the difference in fascicle length (men ～ 37% greater than boys, women ～ 10% greater than girls). It is concluded that the fascicle, muscle and tendon lengthen proportionally during maturation, thus the muscle–tendon stiffness and excursion range are likely to be similar in children and adults but the relatively greater increase in PCSA than fascicle length indicates that adult muscles are better designed for force production than children’s muscles.     

Structure and vascularization of the ventricular myocardium in Holocephali: their evolutionary significance

It was generally assumed that the ventricle of the primitive vertebrate heart was composed of trabeculated, or spongy, myocardium, supplied by oxygen‐poor luminal blood. In addition, it was presumed that the mixed ventricular myocardium, consisting of a compacta and a spongiosa, and its supply through coronary arteries appeared several times throughout fish evolution. Recent work has suggested, however, that a fully vascularized, mixed myocardium may be the primitive condition in gnathostomes. The present study of the heart ventricles of four holocephalan species aimed to clarify this controversy. Our observations showed that the ventricular myocardium of Chimaera monstrosa and Harriotta raleighana consists of a very thin compacta overlying a widespread spongiosa. The ventricle of Hydrolagus affinis is composed exclusively of trabeculated myocardium. In these three species there is a well‐developed coronary artery system. The main coronary artery trunks run along the outflow tract, giving off subepicardial ventricular arteries. The trabeculae of the spongiosa are irrigated by branches of the subepicardial arteries and by penetrating arterial vessels arising directly from the main coronary trunks at the level of the conoventricular junction. The ventricle of Rhinochimaera atlantica has only spongy myocardium supplied by luminal blood. Small coronary arterial vessels are present in the subepicardium, but they do not enter the myocardial trabeculae. The present findings show for the first time that in a wild living vertebrate species, specifically H. affinis, an extensive coronary artery system supplying the whole cardiac ventricle exists in the absence of a well‐developed compact ventricular myocardium. This is consistent with the notion derived from experimental work that myocardial cell proliferation and coronary vascular growth rely on distinct developmental programs. Our observations, together with data in the literature on elasmobranchs, support the view that the mixed ventricular myocardium is primitive for chondrichthyans. The reduction or even lack of compacta in holocephali has to be regarded as a derived anatomical trait. Our findings also fit in with the view that the mixed myocardium was the primitive condition in gnathostomes, and that the absence of compact ventricular myocardium in different actinopterygian groups is the result of a repeated loss of such type of cardiac muscle during fish evolution.     

Organisation and chemical neuroanatomy of the African elephant (<Emphasis Type="Italic">Loxodonta africana</Emphasis>) olfactory bulb

The olfactory system of mammals can be divided into a main and accessory olfactory system with initial processing for each system occurring in the olfactory bulb. The main and accessory olfactory bulbs have similar structural features, even though they appear to be functionally independent. In mammals the main olfactory bulb (MOB) is also one of two established sites of lifelong generation of new cells. The present study describes the histological and immunohistochemical neuroanatomy of the olfactory bulb of the African elephant (Loxodonta africana). The morphology of MOB of the elephant does not differ significantly from that described in other mammals; however, it lacks the internal plexiform layer. In addition, the glomeruli of the glomerular layer are organised in 2–4 “honey-combed” layers, a feature not commonly observed. The cell types and structures revealed with immunohistochemical stains (parvalbumin, calbindin, calretinin, tyrosine hydroxylase, orexin-A, glial fibrillary acidic protein) were similar to other mammals. Neurogenesis was examined using the neurogenic marker doublecortin. Migration of newly generated cells was observed in most layers of the MOB. No accessory olfactory bulb (AOB) was observed. Based on the general anatomy and the immunohistochemical observations, it is evident that the morphology of the African elephant MOB is, for the most part, similar to that of all mammals, although very large in absolute size.