Spondylolysis: its nature and anthropological significance

Spondylolysis of the lower back is a kind of vertebral fracture that is unique to humans being related to anatomical features such as the lumbar curve which facilitate upright posture and bipedal locomotion in this species. It is virtually never seen in children before the age of walking and has not been observed in adults who were never able to walk. Although apparently produced on occasion by acute trauma, spondylolysis usually develops as a fatigue fracture in response to sustained or repeated stress. The occurrence of spondylolysis varies greatly from population to population with the highest frequencies, approaching 50%, seen in northern Alaskan and Greenlandic Eskimos. Males are affected more frequently than females, and the condition is common in athletes, particularly gymnasts, divers, polevaulters, and American football players. It is also seen among heavy laborers, especially if the job requires lifting. Although generally approached as a pathological condition requiring corrective treatment, spondylolysis, as well as the anterior slippage (olisthesis) that frequently accompanies it, usually produces relatively mild symptoms if any at all. In fact, it many even provide advantages such as greater flexibility in the lower back.     

Degenerative spondylolisthesis in ancient and historic skeletons from New Mexico Pueblo sites.

The objective of this study was to identify the presence of degenerative spondylolisthesis in adult Native American skeletons recovered from prehistoric and historic Pueblo sites in New Mexico. The vertebral columns of 491 individuals that were complete enough to allow the necessary observations produced 64 cases, with a total of 74 affected levels. The L5-S1 level was affected most frequently (78%), in contrast to clinical and anatomical studies where the L4-L5 level was usually affected (80%). Age and sex were found to be important factors, with the condition limited to middle and old adults, and occurring in females over males at a ratio of approximately 5:1. Olisthesis was shown to occur only in association with severe osteoarthritis of the zygapophysial joints, but severe osteoarthritis did not always result in olisthesis, particularly in males. Parallel or convergent inferior articular processes were found to increase in frequency in the presence of olisthesis, apparently resulting from degenerative remodeling that produced the olisthesis. The data also suggest that individuals with cranial border shifting in the column may be especially prone to olisthesis. Degenerative olisthesis was also observed in the cervical region.     

Is Preventative Long-Segment Surgery for Multi-Level Spondylolysis Necessary? A Finite Element Analysis Study

Objective

For multi-level spondylolysis patients, surgeons commonly choose to fix all the segments with pars interarticularis defect even those without slippage and not responsible for clinical symptoms. In this study, we tried to study the necessity of the preventative long-segment surgery for the defected segment without slippage in treatment of multi-level spondylolysis patients from a biomechanical perspective.

Method

We established a bi-level spondylolysis model with pars defects at L4 and L5 segments, and simulated posterior lumbar interbody fusion (PLIF) and pedicle screw fixation at L5-S1 level. Then we compared the biomechanical changes at L4 segment before and after surgery in neutral, flexion, extension, lateral bending and axial rotation position.

Results

The stress on L4 pars interarticularis was very similar before and after surgery, and reached the highest in axial rotation. The L3-L4 intradiscal pressure was almost the same, while L4-L5 intradiscal pressure changed a little in lateral bending (increase from 1.993 to 2.160 MPa) and axial rotation (decrease from 1.639 to 1.307 MPa) after surgery. The PLIF surgery caused a little increase of range of motion at adjacent L4-L5 and L3-L4 levels, but the change is very tiny (1 degree).

Conclusion

The PLIF surgery will not cause significant biomechanical change at adjacent segment with pars defect in multi-level spondylolysis. On the contrary, excessive long-segment surgery will damage surrounding soft tissues which are important for maintaining the stability of spine. So a preventative long-segment surgery is not necessary for multi-level spondylolysis as long as there are no soft tissue degeneration signs at adjacent level.     

Growth of the calcareous skeleton during regeneration of spines of the sea urchin,strongylocentrotus purpuratus (stimpson): A light and scanning electron microscopic study

Growth of the skeleton of regenerating spines of the sea urchin, Strongylocentrotus purpuratus, was studied with the light and scanning electron microscopes during the formation of a growth ring or cycle. Growth was initiated about three days after fracture and was linear between 5 and about 40 days after fracture, with a mean rate of 0.16 mm/day. There-after, a decline in growth rate was observed, being attributed to abrasion. The new skeleton first appeared as minute, conical ?micro-spines”? on the fractured surface of the spine shaft initiating regeneration of the inner zone of meshwork. Subsequent growth of micro-spines of both the developing inner zone of meshwork, and an outer zone of radiating wedges, formed a conical fenestrated skeleton on the fractured surface of the shaft. Further deposition of micro-spines along the shaft, initially at the level of fracture, formed meshwork which gradually became solidified externally resulting in a new cycle about 60 days after fracture. In contrast, a new cycle was initiated at the milled ring in non-fractured spines during total regeneration on bare tubercles, demonstrating that growth of spines also takes place in the absence of fracture. Experiments conducted in vitro demonstrate that spine regeneration is not a polar phenomenon.     

Somatic Hybrids of Sunflower (Helianthus annuus L.) Identified at the Callus Stage by Isoenzyme Analysis

Dark grown hypocotyl protoplasts from Helianthus annuus L. cvs. Cerflor and Euroflor were electrically fused to produce somatic hybrids. Following fusion, the protoplasts were cultivated in agarose droplets for four weeks. Macroscopic visible calli (0.1-0.3 mm) were transferred onto solid medium and calli reaching a size of 3 mm were collected. Their isoenzyme patterns were analysed based on two different isoenzymes that allow discrimination between the two cultivars used for fusion. From the examined calli, about 26 % showed an isoenzyme pattern of putative binary heterokaryocytes. The isoenzyme pattern of the non-fused control revealed less than 5% of possibly chimeric colonies.     

海南三亚一头死亡中华白海豚的形态学记录

On February 2,2015, a dead female Indo-Pacific humpback dolphin (Sousa chinensis) was found in the coastal water of Meilian Village, Yacheng Town, Sanya City, Hainan Province, China. It was the first Indo-Pacific humpback dolphin death case ever found in waters southwest of Hainan Island. In the present study, data about external morphology and skeleton system of the dead dolphin were documented, Body length and body mass of the animal were 235.0 cm and ca. 150 kg, respectively, with completely white body color. The cranium of this dolphin wa 189 mm in zygomatic width, and 415 mm in skull length. Its vertebra formula was C6+T12+L10+Ca20=48. It had 12 pairs of ribs and 11 V-bones. According to previous reports, our skeleton sample may have one cervical vertebra missing, and one or more caudal vertebras and V bones missing. More new skeleton samples from the same population are needed to confirm this presumption.     

Spondylolysis, spondylolisthesis, and lumbo-sacral morphology in a medieval English skeletal population

The prevalence of spondylolysis and spondylolisthesis was studied in an adult skeletal series from a rural English medieval archaeological site. Attempts were made to evaluate the association of three aspects of lumbo-sacral skeletal morphology (pelvic incidence (a measure of the anterior inclination of the sacral table), lumbar transverse process width, and the presence of lumbo-sacral spina bifida occulta) with spondylolysis and spondylolisthesis. Results indicated a high prevalence of spondylolysis compared with a modern reference population, but few cases of spondylolisthesis were identified. Analysis of prevalence with respect to age suggests that in the study population, pars interarticularis defects generally formed late in the growth period or early in adult life. The study group showed a high mean pelvic incidence compared with modern Western Europeans, indicating a more steeply inclined sacral table, which may have elevated the risk of developing pars interarticularis defects. However, no statistically valid association could be demonstrated between the presence/absence of spondylolysis and pelvic incidence in the study material. There was no evidence for a link between lumbar transverse process index or lumbo-sacral spina bifida occulta and spondylolysis/spondylolisthesis. It is concluded that the potential role of lumbo-sacral morphology, as well as of activity regimes, should be considered when interpreting spondylolysis in paleopathological studies. If the frequency of spondylolysis is to some extent an indicator of past activity regimes, it may reflect lifestyle in younger individuals rather than in mature adults. Further work investigating the link between spondylolysis and lumbo-sacral morphological variables in premodern populations would be of value.     

FOSSORIAL ADAPTATIONS OF A TAENIOLABIDOID MULTITUBERCULATE MAMMAL FROM THE EOCENE OF CHINA

<正> Fragments of the postcranial skeleton of s taeniolabidoid multituberculate,? Lambdopsalis bulla, from the Eocene of Chins are described. These consist of cervical vertebrae C2-C3 (fused), a fragment of the neural arch of C4, and complete C5-C7, thoracic vertebrae T1-T3, and two humeri, which are the first Complete multituberculate humeri ever described. The fusion of C2 and C3, and the stout structure of the humerus with a very large deltopectoral crest, a wide distal end, and prominent radial and ulnar condyles, indicate a fossorial mode of life for? L. bulla. These postcranial elements and a wide flattened, skull with a vertical occipital plate, suggest adaptstions seen in some modern golden moles and cricetid rodents such as Myospalax that dig with claws and displace the soil with the head.     

Osteological development of the vertebral column and of the caudal complex in Dentex dentex

Osteological development of the vertebral column and caudal complex in common dentex was described under extensive larval rearing conditions. Generally, the cartilaginous bones developed prior to the membranous bones. The development of the axial skeleton began with the formation of the hypural 1, the neural arches 2 and 3, as well as the haemal arches 1–8 at 4·8, 4·9 and 5·0 mm total length ( L _T, measured in vivo ), respectively. By 7·5 mm L _T, all the cartilaginous elements were formed, except for the ventral ribs, which formed between the range of 8·4–18·0 mm L _T. The caudal lepidotrichia were the first membranous bones to appear (5·3 mm L _T) and attain their full meristic count (7·4 mm L _T), followed by the vertebral centra, which formed between 6·6 and 9·7 mm L _T. By 25·0 mm L _T, all the elements were fully ossified except for the ventral ribs. The developmental direction and order of all the elements were studied with respect to their formation and ossification. The results were discussed in the contexts of ichthyoplankton, ecology and aquaculture. Compared with other Sparidae species, common dentex followed a pattern of relatively rapid rate of osteological development.     

四川自贡大山铺蜀龙动物群——简报Ⅳ.兽脚类

建设气龙 (Gasosaurus constructus gen. et sp. nov.) 为自贡大山铺蜀龙动物群中的兽脚类—新属种.本简报对它的形态特征进行了简要的记述.     

Asymmetrical spondylolysis

The objective of this study was to examine examples of spondylolysis in which the pattern of separation was clearly asymmetrical, in order to learn more about the process of bone separation that produces this condition. Although the primary focus was on unilateral complete separation, examples of asymmetry represented by incomplete separation and by complete bilateral separation where the separation sites are in different locations on the two sides were included. Two collections were used, one consisting of Canadian Inuit skeletons curated at the Canadian Museum of Civilization, and the other of 48 individual examples of asymmetrical spondylolysis from sites in a variety of localities curated by several different institutions. The first collection was studied primarily to observe early manifestations of spondylolysis, particularly incomplete separation, while various patterns of asymmetrical complete separation were the focus of the second. The results indicate that asymmetry is part of the earliest osteological picture of spondylolysis, with right-sidedness predominating, a condition perhaps related in some way to handedness. The right-side predominance appears to decrease with age. The ratio of unilateral to bilateral separation ranges from 3-33% in different studies, and a significant number of the unilateral separations have spina bifida occurring in the same vertebra. Overall, the specimens examined here, considered along with clinical cases, nicely illustrate a progression of spondylolysis. A unilateral separation may heal, it may progress to bilateral separation, or it may remain as a permanent condition, producing a pattern of degenerative changes that can include spondylolisthesis. A unilateral healing of bilateral complete separation is likely a rare phenomenon, at least after the separations have reached a certain level of maturity.     

Changes in the novel orphan, C5a receptor (C5L2), during experimental sepsis and sepsis in humans

Sepsis is associated with extensive complement activation, compromising innate immune defenses, especially in neutrophils (PMN). Recently, a second C5a receptor (C5L2) was detected on PMN without evidence of intracellular signaling. The current study was designed to determine changes in C5L2 in blood PMN during sepsis. In vitro exposure of PMN to C5a, but not to fMLP, led to reduced content of C5L2. Following cecal ligation and puncture-induced sepsis in rats, PMN demonstrated a time-dependent decrease in C5L2. In vivo blockade of C5a during experimental sepsis resulted in preservation of C5L2. Similarly, PMN from patients with progressive sepsis showed significantly reduced C5L2 expression (n = 26), which was virtually abolished in patients who developed multiorgan failure (n = 10). In contrast, sepsis survivors exhibited retention of C5L2 (n = 12/13). The data suggest that C5L2 on PMN diminishes during sepsis due to systemic generation of C5a, which is associated with a poor prognosis.     

Calibration of hyperelastic material properties of the human lumbar intervertebral disc under fast dynamic compressive loads

Under fast dynamic loading conditions (e.g. high-energy impact), the load rate dependency of the intervertebral disc (IVD) material properties may play a crucial role in the biomechanics of spinal trauma. However, most finite element models (FEM) of dynamic spinal trauma uses material properties derived from quasi-static experiments, thus neglecting this load rate dependency. The aim of this study was to identify hyperelastic material properties that ensure a more biofidelic simulation of the IVD under a fast dynamic compressive load. A hyperelastic material law based on a first-order Mooney-Rivlin formulation was implemented in a detailed FEM of a L2-L3 functional spinal unit (FSU) to represent the mechanical behavior of the IVD. Bony structures were modeled using an elasto-plastic Johnson-Cook material law that simulates bone fracture while ligaments were governed by a viscoelastic material law. To mimic experimental studies performed in fast dynamic compression, a compressive loading velocity of 1 m/s was applied to the superior half of L2, while the inferior half of L3 was fixed. An exploratory technique was used to simulate dynamic compression of the FSU using 34 sets of hyperelastic material constants randomly selected using an optimal Latin hypercube algorithm and a set of material constants derived from quasi-static experiments. Selection or rejection of the sets of material constants was based on compressive stiffness and failure parameters criteria measured experimentally. The two simulations performed with calibrated hyperelastic constants resulted in nonlinear load-displacement curves with compressive stiffness (7335 and 7079 N/mm), load (12,488 and 12,473 N), displacement (1.95 and 2.09 mm) and energy at failure (13.5 and 14.7 J) in agreement with experimental results (6551 ± 2017 N/mm, 12,411 ± 829 N, 2.1 ± 0.2 mm and 13.0 ± 1.5 J respectively). The fracture pattern and location also agreed with experimental results. The simulation performed with constants derived from quasi-static experiments showed a failure energy (13.2 J) and a fracture pattern and location in agreement with experimental results, but a compressive stiffness (1580 N/mm), a failure load (5976 N) and a displacement to failure (4.8 mm) outside the experimental corridors. The proposed method offers an innovative way to calibrate the hyperelastic material properties of the IVD and to offer a more realistic simulation of the FSU in fast dynamic compression.     

Spondylolysis of the sacrum in Alaskan and Canadian Inuit skeletons

Spondylolysis of the lower back, particularly that involving the isthmus between the superior and inferior articular processes (pars inter-articularis), is generally attributed to stress fracturing caused by movement of the affected vertebra relative to the vertebra below. The finding of isthmic spondylolysis in the first vertebra of a fused sacrum is thus unusual and requires explanation. Although unrepresented in the clinical literature, sacral spondylolysis has been reported for archaeological specimens and appears to be especially prevalent in North American Inuit. A study of 373 Inuit sacra from Alaska and Canada produced 16 examples of spondylolysis (eight from each area). All but one of the affected individuals were male, and nearly all were young adults, many between 18 and 20 years of age. All cases of sacral spondylolysis observed in this study were judged to have resulted from stress fracturing that occurred while S1 was still unfused, and most appear to have been in the process of healing, following fusion of S1 with S2, when death occurred. The high frequency observed in these people is attributed to unusual stresses becoming concentrated in the lower back of adolescent males due to such activities as weight lifting, wrestling, kayak paddling, and harpooning, combined with, and perhaps even contributing to, delayed maturation (S1-S2 fusion) of the sacrum. © 1996 Wiley-Liss, Inc.     

B cell-deficient mice are highly resistant to Leishmania donovani infection, but develop neutrophil-mediated tissue pathology

Resolution of Leishmania infection is T cell-dependent, and B lymphocytes have been considered to play a minimal role in host defense. In this study, the contribution of B lymphocytes to the response against Leishmania donovani was investigated using genetically modified IgM transmembrane domain (muMT) mutant mice, which lack mature B lymphocytes. When compared with wild-type mice, muMT mice cleared parasites more rapidly from the liver, and infection failed to establish in the spleen. The rapid clearance of parasites in muMT mice was associated with accelerated and more extensive hepatic granuloma formation compared with wild-type mice. However, the liver of infected muMT mice also showed signs of destructive pathology, associated with the presence of increased numbers of neutrophils. The role of neutrophils in controlling parasite growth in the viscera was determined by depletion with the mAb RB6-8C5. This treatment led to a dramatic enhancement of parasite growth in both the liver and spleen of muMT and wild-type mice. As assessed by transfer of both normal and chronic-infection serum, Ig protects microMT mice from destructive hepatic pathology, but minimally alters their resistance compared with wild-type mice. However, adoptive transfer of CD4+ and CD8+ T cells into recombinase activating gene 1 (RAG1-/-) recipients, suggested that T cell function was not altered by maturation in a B cell-deficient environment. Taken together, these data suggest an inhibitory role for B lymphocytes in resistance to L. donovani unrelated to the presence or absence of Ig. However, Ig protects muMT mice from the exaggerated pathology that occurs during infection.     

Novel potassium channel openers. Part 4: transformation of the 1,4-benzoxazine skeleton into 1,4-benzothiazine, 1,2,3,4-tetrahydroquinoline, 1,2,3,4-tetrahydroquinoxaline, indoline, and 1,5-benzoxazepine

As part of a search for a new potassium channel opener, the 1,4-benzoxazine skeleton derived from the benzopyran skeleton of cromakalim, was transformed into other fused rings such as 1,4-benzothiazine, 1,2,3,4-tetrahydroquinoline, 1,2,3,4-tetrahydroquinoxaline, indoline, and 1,5-benzoxazepine. The 1,4-benzothiazine derivative displayed approximately 20 times more potent vasorelaxant activity than cromakalim.     

Plasticity of myosin heavy chain expression with temperature acclimation is gradually acquired during ontogeny in the common carp (Cyprinus carpio L.)

Common carp (Cyprinus carpio L.) were reared from hatching until 61 mm total length (TL) at 21 degrees C. At 14 weeks and 20 weeks post-hatch, corresponding to initial lengths of 30 mm and 44 mm respectively, fish were acclimated to 10 degrees C using a rate of cooling of 1 degrees C per day. A statistical model was used to compare the time course in the change of white muscle myofibrillar ATPase activity with temperature acclimation. The myosin heavy chain (MHC) composition of white muscle myofibrils was investigated using peptide mapping. A significant increase in myofibrillar ATPase activity was observed after 2-3 weeks in the 44 mm group, but not until 4-5 weeks in the 30 mm group. when they had reached 37 mm TL. The MHC banding pattern of 120 mm TL fish acclimated to 10 degrees C or 21 degrees C for a minimum of 6 weeks were distinct from each other. The MHC peptide map characteristic of 10-degrees C-acclimated fish was not observed in individuals less than 37 mm length. We therefore conclude that the capacity to alter the composition and properties of myofibrils with cold acclimation is acquired in juvenile carp at around 37 mm TL.     

Expression of secreted frizzled related protein 1, a Wnt antagonist, in brain, kidney, and skeleton is dispensable for normal embryonic development

Secreted frizzled related protein-1 (sFRP1), an antagonist of Wnt signaling, regulates cell proliferation, differentiation and apoptosis and negatively regulates bone formation. The spatial and temporal pattern of endogenous sFRP1 expression and loss-of-function were examined in the sFRP1-LacZ knock-in mouse (sFRP1-/-) during embryonic development and post-natal growth. beta-gal activity representing sFRP1 expression is robust in brain, skeleton, kidney, eye, spleen, abdomen, heart and somites in early embryos, but sFRP1 gene inactivation in these tissues did not compromise normal embryonic and post-natal development. Kidney histology revealed increased numbers of glomeruli in KO mice, observed after 5 years of breeding. In the skeleton, we show sFRP1 expression is found in relation to the mineralizing front of bone tissue during skeletal development from E15.5 to birth. Trabecular bone volume and bone mineral density in the sFRP1-/- mouse compared to WT was slightly increased during post-natal growth. Calvarial osteoblasts from newborn sFRP1-/- mice exhibited a 20% increase in cell proliferation and differentiation at the early stages of osteoblast maturation. sFRP1 expression was observed in osteoclasts, but this did not affect osteoclast number or activity. These findings have identified functions for sFRP1 in kidney and bone that are not redundant with other sFRPs. In summary, the absence of major organ abnormalities, the enhanced bone formation and a normal life span with no detection of spontaneous tumors suggests that targeting sFRP1 can be used as a therapeutic strategy for increasing bone mass in metabolic bone disorders or promoting fracture healing by modulating Wnt signaling.     

The Alto Salaverry child: a case of anemia from the Peruvian preceramic.

Excavations during 1974 at the Peruvian Preceramic site of Alto Salaverry led to the discovery of a child's skeleton. The fragmentary skeleton exhibits cribra orbitalia, a pitting of the orbital roof associated with anemia. This specimen provides the first evidence of anemia in a population of the predominantly non-agricultural Peruvian Preceramic and extends the antiquity of the pathology among Precolumbian Peruvians.