Programmed genome editing of the omega-1 ribonuclease of the blood fluke, Schistosoma mansoni

CRISPR/Cas9-based genome editing has yet to be reported in species of the Platyhelminthes. We tested this approach by targeting omega-1 (ω1) of Schistosoma mansoni as proof of principle. This secreted ribonuclease is crucial for Th2 polarization and granuloma formation. Schistosome eggs were exposed to Cas9 complexed with guide RNA complementary to ω1 by electroporation or by transduction with lentiviral particles. Some eggs were also transfected with a single stranded donor template. Sequences of amplicons from gene-edited parasites exhibited Cas9-catalyzed mutations including homology directed repaired alleles, and other analyses revealed depletion of ω1 transcripts and the ribonuclease. Gene-edited eggs failed to polarize Th2 cytokine responses in macrophage/T-cell co-cultures, while the volume of pulmonary granulomas surrounding ω1-mutated eggs following tail-vein injection into mice was vastly reduced. Knock-out of ω1 and the diminished levels of these cytokines following exposure showcase the novel application of programmed gene editing for functional genomics in schistosomes.

Schistosomiasis is a tropical disease that can cause serious health problems, including damage to the liver and kidneys, infertility and bladder cancer. Nearly a quarter billion people are currently infected, mostly in poor regions of sub-Saharan Africa, the Philippines and Brazil.

A freshwater worm known as Schistosoma mansoni causes the disease. These parasites enter the human body by burrowing into the skin; once in the bloodstream, they move to various organs where they rapidly start to reproduce. Their eggs release several molecules, including a protein known as omega-1 ribonuclease, which can damage the surrounding tissues.

A gene editing technique called CRISPR/Cas9 allows scientists to precisely target and then deactivate the genetic information a cell needs to produce a given protein. While the tool has been used in other species before, it was unknown if it could be applied to S. mansoni. Here, Ittiprasert et al. harnessed CRISPR/Cas9 to deactivate the gene that codes for omega-1 ribonuclease and create parasites that do not produce the protein, or only very little of it. The experiments showed that mice infected with the gene-edited worm eggs displayed far fewer symptoms of schistosomiasis compared to those that carry the non-edited parasites.

Alongside this work, Arunsan et al. used CRISPR/Cas9 to inactivate a gene in another species of worm that can cause liver cancer in humans. Together, these findings demonstrate for the first time that the gene editing method can be adapted for use in parasitic flatworms, which are a major public health problem in tropical climates. This tool should help scientists understand how the parasites invade and damage our bodies, and provide new ideas for treatment and disease control.

Activation of liver X receptors inhibits hedgehog signaling, clonogenic growth, and self-renewal in multiple myeloma

The Hedgehog (Hh) signaling pathway is aberrantly activated in a wide variety of human cancers, and recent clinical studies have demonstrated that pathway inhibitors are effective in advanced basal cell carcinoma (BCC). The majority of these agents have been designed to target SMOOTHENED (SMO), a transmembrane regulator of Hh signaling, but subsequent mutations in SMO have been found to generate drug resistance. In other cancers, oncogenic events that bypass SMO may activate canonical Hh signaling, and SMO antagonists have not demonstrated significant activity in several diseases. Therefore, alternative strategies targeting the Hh pathway downstream of SMO may have clinical utility. Liver X receptors (LXR) regulate cholesterol and fatty acid homeostasis, and LXR activation can inhibit the Hh pathway in normal mouse embryonic fibroblasts. We examined the effects of LXR activation on Hh signaling in human multiple myeloma cells and found that LXR agonists inhibited Hh pathway activity and clonogenic tumor growth in vitro. LXR activation also inhibited putative multiple myeloma cancer stem cells in vivo leading to the loss of tumor initiating and self-renewal potential. Finally, Hh signaling was inhibited downstream of SMO, suggesting that LXR agonists may represent a novel strategy to target pathogenic Hh signaling as well as treat multiple myeloma.

A bis-benzylidine piperidone targeting proteasome ubiquitin receptor RPN13/ADRM1 as a therapy for cancer

The bis-benzylidine piperidone RA190 covalently binds to cysteine 88 of ubiquitin receptor RPN13 in the 19S regulatory particle and inhibits proteasome function, triggering rapid accumulation of polyubiquitinated proteins. Multiple myeloma (MM) lines, even those resistant to bortezomib, were sensitive to RA190 via endoplasmic reticulum stress-related apoptosis. RA190 stabilized targets of human papillomavirus (HPV) E6 oncoprotein, and preferentially killed HPV-transformed cells. After oral or intraperitoneal dosing of mice, RA190 distributed to plasma and major organs except the brain and inhibited proteasome function in skin and muscle. RA190 administration profoundly reduced growth of MM and ovarian cancer xenografts, and oral RA190 treatment retarded HPV16(+) syngeneic mouse tumor growth, without affecting spontaneous HPV-specific CD8(+) T cell responses, suggesting its therapeutic potential.

Development and maintenance of cancer stem cells under chronic inflammation

In many human cancers, tumorigenic potential is not equally shared by all cells but is restricted to phenotypically distinct subpopulations termed cancer stem cells. Cancer stem cells are also capable of both self-renewal and differentiation, and these functional properties have been suggested to play major roles in tumor initiation and progression. The factors responsible for the development of cancer stem cells and their subsequent regulation are unclear, but several chronic inflammatory states have been associated with an increased risk of malignancy. Therefore, it is possible that specific processes associated with chronic inflammation, as well as the adaptation to cellular stress, regulate cancer stem cells. Several factors associated with chronic inflammation, including cytokines, oxidative stress, and hypoxia, induce the activation of specific cellular response programs that can affect the survival, proliferation, metabolism, and differentiation of cancer cells, as well as the self-renewal and quiescence of normal stem cells. In this review, we discuss how these adaptive processes potentially become subverted to enhance the development and function of cancer stem cells.

Afebrile Plasmodium falciparum parasitemia decreases absorption of fortification iron but does not affect systemic iron utilization: a double stable-isotope study in young Beninese women

BACKGROUND

Iron deficiency anemia (IDA) affects many young women in sub-Saharan Africa. Its etiology is multifactorial, but the major cause is low dietary iron bioavailability exacerbated by parasitic infections such as malaria.

OBJECTIVE

We investigated whether asymptomatic Plasmodium falciparum parasitemia in Beninese women would impair absorption of dietary iron or utilization of circulating iron.

DESIGN

Iron absorption and utilization from an iron-fortified sorghum-based meal were estimated by using oral and intravenous isotope labels in 23 afebrile women with a positive malaria smear (asexual P. falciparum parasitemia; > 500 parasites/μL blood). The women were studied while infected, treated, and then restudied 10 d after treatment. Iron status, hepcidin, and inflammation indexes were measured before and after treatment.

RESULTS

Treatment reduced low-grade inflammation, as reflected by decreases in serum ferritin, C-reactive protein, interleukin-6, interleukin-8, and interleukin-10 (P < 0.05); this was accompanied by a reduction in median serum hepcidin of ≈ 50%, from 2.7 to 1.4 nmol/L (P < 0.005). Treatment decreased serum erythropoietin and growth differentiation factor 15 (P < 0.05). Clearance of parasitemia increased geometric mean dietary iron absorption (from 10.2% to 17.6%; P = 0.008) but did not affect systemic iron utilization (85.0% compared with 83.1%; NS).

CONCLUSIONS

Dietary iron absorption is reduced by ≈ 40% in asymptomatic P. falciparum parasitemia, likely because of low-grade inflammation and its modulation of circulating hepcidin. Because asymptomatic parasitemia has a protracted course and is very common in malarial areas, this effect may contribute to IDA and blunt the efficacy of iron supplementation and fortification programs. This trial was registered at clinicaltrials.gov as NCT01108939.

Growth differentiation factor 15 in erythroid health and disease

PURPOSE OF REVIEW

Growth differentiation factor 15 (GDF15) was identified as a hepcidin-suppression factor that is expressed at high levels in patients with ineffective erythropoiesis. This review addresses the regulation, expression and potential functions of GDF15 in the context of erythroid biology.

RECENT FINDINGS

GDF15 expression during late erythroid differentiation was discovered as part of an erythroblast transcriptome project. As GDF15 expression is associated with cellular stress or apoptosis, further investigation of the cytokine was focused upon its involvement in ineffective erythropoiesis. Remarkably high serum levels were detected in patients with thalassemia syndromes, congenital dyserythropoiesis and some acquired sideroblastic anemias. High-level GDF15 expression is not a feature of normal erythropoiesis, or erythroid recovery after bone-marrow transplantation. As GDF15 is a transforming growth factor-beta superfamily member, it was investigated as an effector of ineffective erythropoiesis that suppresses hepcidin expression despite iron overloading.

SUMMARY

In contrast to the low levels of GDF15 expressed during normal erythropoiesis, ineffective erythropoiesis causes high-level expression of GDF15. In patients with thalassemia and related anemias, GDF15 expression may contribute to iron overloading or other features of the disease phenotype.

Expression of growth differentiation factor 15 is not elevated in individuals with iron deficiency secondary to volunteer blood donation

BACKGROUND

Low serum hepcidin levels provide a physiologic response to iron demand in patients with iron deficiency (ID). Based on a discovery of suppressed hepcidin expression by a cytokine named growth differentiation factor 15 (GDF15), it was hypothesized that GDF15 may suppress hepcidin expression in humans with ID due to blood loss.

STUDY DESIGN AND METHODS

To test this hypothesis, GDF15 and hepcidin levels were measured in peripheral blood from subjects with iron-deficient erythropoiesis before and after iron supplementation.

RESULTS

Iron variables and hepcidin levels were significantly suppressed in iron-deficient blood donors compared to healthy volunteers. However, ID was not associated with elevated serum levels of GDF15. Instead, iron-deficient subjects' GDF15 levels were slightly lower than those measured in the control group of subjects (307 +/- 90 and 386 +/- 104 pg/mL, respectively). Additionally, GDF15 levels were not significantly altered by iron repletion.

CONCLUSIONS

ID due to blood loss is not associated with a significant change in serum levels of GDF15.

Iron metabolism in heterozygotes for hemoglobin E (HbE), alpha-thalassemia 1, or beta-thalassemia and in compound heterozygotes for HbE/beta-thalassemia

BACKGROUND

Despite large populations carrying traits for thalassemia in countries implementing universal iron fortification, there are few data on the absorption and utilization of iron in these persons.

OBJECTIVE

We aimed to determine whether iron absorption or utilization (or both) in women heterozygous for beta-thalassemia, alpha-thalassemia 1, or hemoglobin E (HbE) differed from that in control subjects and compound HbE/beta-thalassemia heterozygotes.

DESIGN

In Thai women (n = 103), red blood cell indexes, iron status, non-transferrin-bound iron, and growth differentiation factor 15 were measured, and body iron was calculated. Fractional iron absorption was measured from meals fortified with isotopically labeled ((57)Fe) Fe sulfate, and iron utilization was measured by the infusion of ((58)Fe) Fe citrate.

RESULTS

Iron utilization was approximately 15% lower in alpha-thalassemia 1 or beta-thalassemia heterozygotes than in controls. When corrected for differences in serum ferritin, absorption was significantly higher in the alpha- and beta-thalassemia groups, but not the HbE heterozygotes, than in controls. HbE/beta-thalassemia compound heterozygotes had lower iron utilization and higher iron absorption and body iron than did controls. Nontransferrin-bound iron and growth differentiation factor 15 were higher in the compound heterozygotes, but not in the other groups, than in the controls.

CONCLUSIONS

In alpha-thalassemia 1 and beta-thalassemia heterozygotes with ineffective erythropoesis, dietary iron absorption is not adequately down-regulated, despite a modest increase in body iron stores. In populations with a high prevalence of these traits, a program of iron fortification could include monitoring for possible iron excess and for iron deficiency.

High levels of GDF15 in thalassemia suppress expression of the iron regulatory protein hepcidin

In thalassemia, deficient globin-chain production during erythropoiesis results in anemia. Thalassemia may be further complicated by iron overload (frequently exacerbated by blood transfusion), which induces numerous endocrine diseases, hepatic cirrhosis, cardiac failure and even death. Accumulation of iron in the absence of blood transfusions may result from inappropriate suppression of the iron-regulating peptide hepcidin by an erythropoietic mechanism. To test this hypothesis, we examined erythroblast transcriptome profiles from 15 healthy, nonthalassemic donors. Growth differentiation factor 15 (GDF15), a member of the transforming growth factor-beta superfamily, showed increased expression and secretion during erythroblast maturation. Healthy volunteers had mean GDF15 serum concentrations of 450 +/- 50 pg/ml. In comparison, individuals with beta-thalassemia syndromes had elevated GDF15 serum levels (mean 66,000 +/- 9,600 pg/ml; range 4,800-248,000 pg/ml; P < 0.05) that were positively correlated with the levels of soluble transferrin receptor, erythropoietin and ferritin. Serum from thalassemia patients suppressed hepcidin mRNA expression in primary human hepatocytes, and depletion of GDF15 reversed hepcidin suppression. These results suggest that GDF15 overexpression arising from an expanded erythroid compartment contributes to iron overload in thalassemia syndromes by inhibiting hepcidin expression.

Slit3 regulates cell motility through Rac/Cdc42 activation in lipopolysaccharide-stimulated macrophages

Three slit genes, slit1 to slit3, have been cloned to date. Slit1 and slit2 act as chemorepellent factors for axon guidance. Slit3 is involved in the formation of the diaphragm and kidney during embryogenesis. However, its molecular function remains unclear. We found that slit3 expression was induced by lipopolysaccharide (LPS)-stimulation in macrophages and that it was localized in the mitochondria and along the plasma membrane. Silencing of slit3 expression by RNA interference reduced cell motility and Rac/Cdc42 activation. These results suggest that slit3 functions as an intracellular signaling molecule for cell motility as part of the LPS-induced signaling cascade.

Expression patterns of the slit subfamily mRNA in canine malignant mammary tumors

Slit, a secreted protein, functions as a chemorepellent factor in axon guidance and neuronal migration and as an inhibitor in leukocyte chemotaxis. In humans, slit2 protein attracts endothelial cells and promotes tube formation in the tumor angiogenic mechanism. In this study, we cloned a part of the canine slit subfamily and examined the expression of slit subfamily mRNAs in 3 normal canine mammary glands and 11 mammary tumor samples by RT-PCR. The cloned part of the slit gene sequences showed high similarity to those of the human, mouse, and rat. The mRNAs were expressed at low levels in the normal mammary gland. The expression levels of slit1 mRNA were low in both the normal and tumor tissues. In contrast, the expression of slit2 mRNA increased in most of the malignant mammary tumors, and an increase in slit3 mRNA expression was observed in 2 of the malignant mixed tumors. These results suggest that the expression of slit2 plays an important role in tumor angiogenesis in canine mammary gland tumors and that slit2 can be a putative marker for malignancy diagnosis of these tumors.

Expression of a chemorepellent factor, Slit2, in peripheral nerve regeneration

The expression of mRNA for chemorepellent factors slit1 and slit2 in rat peripheral nerve regeneration was examined. The mRNA of slit2 increased when the continuity of basal lamina tubes was disrupted, not when it remained and the Slit2 protein was located in Schwann cells. These results suggest that disruption of the continuity of basal lamina tubes induces the expression of slit2 in Schwann cells during peripheral nerve regeneration.

Expression and Function of Slit1 , a Novel Alternative Splicing Product for Slit1

Slits are large molecular and extracellular glycoproteins that may function as chemorepellents in axon guidance and neural cell migration. The heterogeneity of the mRNA for slit has been described. Its variants indicate considerable potential for alternative splicing, resulting in the generation of multiple protein isoforms. We examined the regions in which these isoforms are expressed, and identified the highest expression of a splicing product for slit1 in rat brain rather than in other organs. The splicing product, Slit1alpha, arises through alternative splicing at the C-terminus of Slit1, causing defects in the cysteine knot domain. We show that slit1alpha exists in the hippocampus and cerebral cortex in rat brain by in situ hybridization, and that it acts as a chemorepellent in olfactory bulb axon guidance in vitro. These findings suggest that Slit1alpha is an active Slit1 protein specific in the vertebrate nervous system.

Occurrence of coenzyme forms of vitamin B12 in a cultured purple laver (Porphyla yezoensis)

Porphyra yezoensis (Susabinori, an edible purple laver), which was cultured aseptically for 12 weeks and then lyophilized, contained 50+/-2 microg/g of vitamin B(12) per 100 g dry weight. Coenzyme forms of vitamin B(12) (about 60% of the total vitamin B(12)) were found in the cultured purple laver aseptically, which may have the ability to biosynthesize the coenzymes.

Circadian variation of basal total vascular tone and chronotherapy in patients with vasospastic angina pectoris

Vasospastic angina pectoris (VSA) is an anginal attack which occurs characteristically between night and early morning. The aim of this study was to clarify the cause of VSA. The subjects consisted of 16 patients with VSA, 18 patients with effort angina (EAP) and 15 healthy individuals, who were used as the control group. Subjects were attached to an ambulatory blood pressure monitor and a non-invasive continuous cardiac output monitor concurrently, over a 24-hour period. Mean blood pressure (MBP), and cardiac index (CI) were measured. Then basal total vascular tone (TVT) was calculated as follows: basal TVT = (MBP/CI) x 1,332 dyne/sec/cm5. The decrement of CO was greater during sleeping hours as compared with the decrement of the MBP in the VSA group. Nocturnal basal TVT was significantly greater in the VSA group than in the EAP group or the control group. The increased nocturnal basal TVT was significantly suppressed by long acting calcium antagonists to the level of the EAP and the control groups. The treatment also decreased the frequency of ischemic attacks.

[An autopsy case of atypical Friedreich's ataxia with chronic idiopathic intestinal pseudo-obstruction]

We report a 58-year-old man with slowly progressive muscle atrophy and weakness in the four extremities, accompanying cerebellar ataxia and sensory impairment of all modalities. He was a product of consanguineous marriage. His neurological manifestations began in childhood. He was admitted to our hospital because of marked abdominal distension and pretibial edema with hypoalbuminemia and hyperlipidemia. Neuroimaging studies showed marked atrophy of the cerebellum and spinal cord. Nerve conduction studies presented with slowing and sural nerve biopsy revealed demyelination with onion-bulbs. Abdominal distension was interpreted to be caused by chronic idiopathic intestinal pseudo-obstruction (CIIP), leading to protein-losing gastroenteropathy and hypalbuminemia caused by the CIIP. He died of DIC by myelodysplasic syndrome and DIC, two years later. Postmortem study demonstrated with severe loss of anterior horn cells and gliosis in the spinal cord. The Clarke's column was also affected. There was symmetrical degeneration in the dorsal column and corticospinal tracts. The cerebellum showed atrophy of molecular layer, prominent loss of Purkinje's cells and sparse granular cell layer, but no obvious change in the dentate nucleus. Neuronal loss in the dorsal root ganglia was remarkable. There were no alternations in the cerebral cortex, striatum, thalamus, subthalamic nucleus, and pontine nucleus, except for mild changes in substantia nigra and inferior olivary nucleus. This case was clinically suspected either of variant of Friedreich's ataxia or an early onset ataxia associated with hypoalbuminemia (EOAHA), although marked autonomic dysfunction was atypical. But the postmortem study, demonstrated with marked neuronal loss in anterior horn cells and cerebellan cortex and rather suggested an independent category of this case.

Regional variations in the progression of bone loss in two different mouse osteopenia models

Differences in trabecular and cortical bone loss have been demonstrated clinically, but differences in bone loss at different skeletal sites remain unclear. We examined regional variations in bone loss histomorphometrically in two strains of mice in which osteopenia progresses spontaneously: tiptoe-walking Yoshimura (twy) mice (from 4 to 37 weeks of age) and senescent ICR mice (from 4 to 88 weeks of age). Morphometrical measurements were obtained to investigate the changes with age in trabecular bone area and anterior cortical bone width in the lumbar vertebral body, trabecular bone area in the tibia, bone area in the parietal bone, and the cortical index in the humerus. Results showed that, in twy mice, trabecular turnover was higher than in ICR mice, and bone loss progressed in the following order: tibial trabecular bone, lumbar trabecular bone, parietal bone, lumbar anterior cortical bone, and the humerus. In ICR mice, bone formation declined after 60 weeks. Bone loss progressed in tibial trabecular bone and the parietal bone at 60 weeks of age, followed by lumbar trabecular bone, lumbar anterior cortical bone, and the humerus at 88 weeks of age. Bone loss varied at each site and between the two mouse strains, with different bone turnover rates. The findings of the present study indicate that special attention should be paid to regional variations in the progression of bone loss associated with differences in pathologic features.

Cervical myelopathy caused by pseudoarthrosis between the atlas and axis associated with diffuse idiopathic skeletal hyperostosis

STUDY DESIGN

This is a report of a patient with severe cervical myelopathy due to pseudoarthrosis between the posterior tubercle of the atlas and the spinous process of the axis, associated with diffuse idiopathic skeletal hyperostosis. Radiographs of 170 patients with neck pain were reviewed to identify lesions involving abnormal contact between the atlas and axis.

OBJECTIVE

Based on an analysis of 170 radiographs, the prevalence of the reported condition was estimated.

SUMMARY OF BACKGROUND DATA

A number of histologic studies on pseudoarthrosis involving the lumbar spine have been reported. In contrast, lesions between the posterior tubercle of the atlas and the spinous process of the axis have not been reported in association with cervical myelopathy.

METHODS

Clinical and pathologic features of a patient with pseudoarthrosis between the posterior tubercle of the atlas and the spinous process of the axis were investigated. Radiographs of 170 Japanese patients over 40 years old were examined, and abnormal contact between the atlas and axis was classified into two groups based on the degree of spinal hyperostosis.

RESULTS

Of 170 patients, 53 showed abnormal contact between the atlas and axis. The prevalence of abnormalities in the pronounced hyperostosis group (Forestier's stages II and III) was much higher than in the group with normal or slight hyperostosis. Two men had radiographic patterns showing osteophytes projecting into the spinal canal and associated with marked cervical myelopathy.

CONCLUSION

In the group with pronounced hyperostosis, pseudoarthrosis or a variant can cause serious problems in the upper cervical spine that should not be overlooked.

Alteration of elastin in aorta from diabetics

The differences in desmosine, isodesmosine (DID), hydroxyproline and cholesterol in the human thoracic aorta from diabetic (n = 16) and non-diabetic (n = 17) autopsy subjects were investigated. DID was analyzed by the use of high performance liquid chromatography. The amount of DID, and total DID (DID+reduced DID) tended to be lower in the diabetic than in non-diabetic subjects. The ratio of DID or total DID to hydroxyproline was significantly decreased in diabetic compared to non-diabetic subjects. Amount of DID, reduced DID and total DID were significantly lower in aorta with plaque formation than that without plaque or ulcer. Multiple regression analysis showed that amount of cholesterol, DID, reduced DID and age were significantly associated with dry weight per area of the aorta. A similar association was not observed in non-diabetic subjects. Compositional changes of aortic cholesterol and elastin have a closer relationship with atherosclerosis in diabetic than in non-diabetic subjects.

Long-term follow-up study of anterior surgery for cervical spondylotic myelopathy with special reference to the magnetic resonance imaging findings in 52 cases

A series of 151 patients with cervical spondylotic myelopathy (CSM) were surgically treated through an anterior approach in the period from 1960 to 1987. Particular attention was given to the results of the 52 patients who were operated on more than 12 years ago. Satisfactory short-term results were obtained in all but the few who had incomplete decompression. In these patients, function deteriorated within five years. A disturbing incidence of progression of myelopathy was noted ten years after surgery. Magnetic resonance imaging identified many of the causes (e.g., newly developed intervertebral disk herniation and progression of spondylosis associated with spinal malalignment in both cephalad and caudal directions). Other adverse changes were hypertrophy of the yellow ligament and ossification of the posterior longitudinal ligament. The new and improved techniques consist of decompression to a width of 16 mm or more with intraoperative ultrasonography in addition to extirpation of the posterior longitudinal ligament. This new measure may reduce the incidence of late neurologic deterioration.

[Experimental study on the spinal lesions in hyperostotic mouse (twy/twy): special reference to the pathogenesis of the ossification of the spinal ligaments and to the action of ethane-1-hydroxy-1, 1-diphosphonate (EHDP)]

The hyperostotic changes in the spine of the twy mouse and the action of ethane-1-hydroxy-1, 1-diphosphonate (EHDP) on those hyperostotic changes were studied histomorphometrically. The periosteal bone formation and the endosteal bone resorption in the anterior cortex of the vertebral bodies of the twy mouse continued even after maturation, resulting in the anterior cortex shifting to the anterior direction. In parallel with these changes, calcification in the enthesis (to which spinal ligaments and the outer layer of disc fibrosis are attached) continued, ending in ankylosis of the whole spine. It was similar to a membranous ossification. Moreover calcification in these regions was most sensitively inhibited by EHDP and reappeared as soon as the discontinuation of EHDP. These findings showed that the pathogenesis of the twy mouse was the hyperostosis which continued even after maturation in the genetical region of a membranous ossification, especially in the enthesis. Further they appeared to be similar to the initial changes in ankylosing spinal hyperostosis or the ossification of the spinal ligaments. In addition, our results provided evidence for the usefulness of EHDP in the twy mouse.