Morphological analysis of germ cell apoptosis during postnatal testis development in normal and Hsp 70-2 knockout mice

The present study examined the occurrence of apoptotic cell death in the testis of wild-type mice from postnatal days 3 to 26 and in juvenile Hsp 70-2 knockout mice. Adult Hsp 70-2 knockout males are infertile and lack spermatids and spermatozoa (Dix et al. [1996a] Proc. Natl. Acad. Sci. U.S.A. 93:3264-3268). To identify the cell types undergoing apoptosis, we also examined the relationship between the occurrence of apoptotic cell death and the expression pattern of the Hsp 70-2 gene product (heat-shock protein 70-2 [HSP70-2]; marker for spermatocytes and spermatids), germ cell nuclear antigen 1 (GCNA1;marker for spermatogonia and spermatocytes), and vimentin (marker for Sertoli cells). This study shows that during postnatal development of the wildtype mouse testis (1) the percentage of apoptotic cell death detected by the TdT-mediated dUTP-biotin nick end labeling (TUNEL) method is higher in mice from days 8 to 22 than in younger or older mice, (2) the majority of apoptotic cells are spermatogonia and less frequently are spermatocytes, and (3) the degenerative cell death of spermatogonia and primary spermatocytes involves apoptosis with fragmentation of DNA. The analysis of apoptotic cell death in the testes of juvenile Hsp 70-2 knockout mice showed an additional increased level of apoptosis at day 17, during the first wave of spermatogenesis, in pachytene spermatocytes.

A case of Bednar tumor. Immunohistochemical positivity for CD34

A 42-year-old Japanese man with a Bednar tumor is described. The skin showed a slightly elevated, red, partially dark blue, dermal nodule growing into the deep subcutaneous tissue. The histological specimen showed two types of tumor cells, spindle-formed cells with no melanin granules and melanin-laden cells. Immunohistochemical stainings for CD34 and S-100 protein revealed that the former cells showed positivity only for CD34, while the latter were only positive for S-100 protein. These results suggest that the Bednar tumor is a dermatofibrosarcoma protuberans in which melanin-laden cells coexist.

Physical and functional interactions between Stat5 and the tyrosine-phosphorylated receptors for erythropoietin and interleukin-3

Erythropoietin (Epo) and interleukin-3 (IL-3) stimulate activation of the Jak2 tyrosine kinase and induce tyrosine phosphorylation and activation of Stat5. In the present study, we have shown that Epo or IL-3 stimulation induces binding of Stat5 to the tyrosine-phosphorylated Epo receptor (EpoR) or IL-3 receptor beta subunit (betaIL3), respectively, in IL-3-dependent 32D cells expressing the EpoR. The binding of Stat5 to these cytokine receptors was shown to be rapid and transient, occurring within 1 minute of stimulation of cells and significantly decreasing after 5 minutes of cell treatment. In vivo binding experiments in COS cells showed that binding of Stat5 to the EpoR was mediated through the Stat5 Src homology 2 (SH2) domain. In vitro binding studies further showed that Stat5, but not other Stats examined, bound specifically to tyrosine-phosphorylated recombinant EpoR fusion proteins. In these in vivo and in vitro binding studies, Stat5 bound, albeit to a lesser degree, to truncated EpoR mutants in which all the intracellular tyrosines except Y-343 were removed. Furthermore, EpoR-derived synthetic phosphotyrosine peptides corresponding to Y-343, Y-401, Y-431, and Y-479 inhibited the in vitro binding of Stat5. When expressed in 32D cells, a mutant EpoR in which all the intracellular tyrosines were removed by carboxy-terminal truncation showed a significantly impaired ability to induce tyrosine phosphorylation of Stat5, particularly at low concentrations of Epo, but exhibited an increased sensitivity to Epo for growth signaling as compared with the wild-type EpoR. These results indicate that Stat5 specifically and transiently binds to the EpoR through the interaction between the Stat5 SH2 domain and specific phosphorylated tyrosines, including Y-343, in the EpoR cytoplasmic domain. It was implied that betaIL3 may also have similar Stat5 docking sites. The Stat5 docking sites in the EpoR were shown to facilitate specific activation of Stat5, which, however, may not be required for the EpoR-mediated growth signaling.

Guillain-Barré syndrome and ethylene diamine tetraacetic acid-dependent pseudothrombocytopenia associated with mumps

A 35-year-old man with Guillain-Barré syndrome and ethylene diamine tetraacetic acid (EDTA)-dependent pseudothrombocytopenia associated with serologically-confirmed mumps is presented. A polyneuropathy developed 18 days after the onset of mumps, that improved with plasmapheresis. A decreased platelet count was observed 25 days after the onset of mumps attributed to platelet agglutination in blood anticoagulated with EDTA, and the agglutination was prevented by other anticoagulants. Guillain-Barré syndrome associated with mumps is rare and EDTA-dependent pseudothrombocytopenia following mumps has never been documented. This represents the first report of Guillain-Barré syndrome and EDTA-dependent pseudothrombocytopenia following mumps. Furthermore, our findings suggest activation of the humoral immune response as a potential pathogenesis.

Synthesis and biological activity of four kinds of reversed peptides

We have synthesized four kinds of reversed peptides of various physiologically active peptides, which inhibit TNF (tumor necrosis factor) cytotoxicity, produce NGF (nerve growth factor), exert antimicrobial activity and inhibit cell attachment, respectively. They were examined for their biological activity in comparison with that of normal peptides, that is, naturally occurring peptides. The reversed peptides induce similar activities, but to a lesser extent than those of the normal peptides, respectively. These results indicate that there may be conformationally ambiguous binding in some of the naturally occurring ligand-protein interactions. This method may be useful as a tool to rapidly generate a novel lead peptide with the desired biological function from a naturally occurring active peptide.

Clinicopathological study of choroid plexus tumors: immunohistochemical features and evaluation of proliferative potential by PCNA and Ki-67 immunostaining

This report concerns the retrospective immunohistochemical characterization and evaluation of the proliferative potential of eight choroid plexus tumors (CPTs) that included six cases of choroid plexus papilloma (CPP), one of whom had a recurrence, and two cases of choroid plexus carcinoma (CPC). Antibodies to prealbumin, glial fibrillary acidic protein (GFAP), vimentin, keratin, and carcinoembryonic antigen (CEA) were used to determine the immunohistochemical features of interest. The proliferative potential was evaluated with antibodies to proliferating cell nuclear antigen (PCNA) and Ki-67. Antibody binding was visualized by the avidin-biotin-peroxidase complex (ABC) method. Immunoreactivity was scored on a-to 4+ scale, and in the case of PCNA and Ki-67, expected as staining index (SI). All seven CPP specimens were immunostained for prealbumin, but not for CEA. Expression of GFAP, vimentin and keratin varied from one CPP case to another. Both CPCs expressed CEA, but not prealbumin, GFAP and keratin; one of them was vimentin-positive. As determined by immunostaining for Ki-67, the proliferative potential was lower in the CPPs than in the CPCs. Among the former, the highest Ki-67 SI was seen in the primary lesion of a recurring papilloma. On the other hand, immunostaining for PCNA gave less consistent SI values. Our results show that immunohistochemical assays for prealbumin and CEA expression are of significant value for the differential diagnosis of CPPs and CPCs, and that high Ki-67 SI values may serve as an indicator of CPP recurrence, even if the primary lesion is benign.

Cloning and sequence analysis of a cDNA encoding salmon (Onchorhynchus keta) liver transglutaminase

We isolated cDNA clones encoding a transglutaminase (TGase: EC 2.3.2.13) from a salmon (Onchorhynchus keta) cDNA library prepared from the liver. In the cDNA sequence combined, an open reading frame coding for a protein of 680 aa was found. The deduced sequence showed a considerable similarity (62.4%) to that of red sea bream TGase. By comparison of sequence similarity to other TGases, the structure of salmon TGase was like tissue type TGases, rather than membrane-associated type or plasma type TGases. As a structural feature of salmon TGase, 3 aa residues were substituted in the 25 aa sequence around the active site Cys residue, which is conserved among several tissue type TGases. The critical residues thought to form the catalytic-center triad (Cys272, His331, and Asp301) were found in the highly conserved region, but the region surrounding Tyr511, which corresponds to the residue participates in hydrogen-bond interactions of active center domain, was less similar to other TGases, except for red sea bream TGase. These finding suggests that the overall structure of fish TGase resembles tissue-type TGases, but has some unique structure.

Clinicopathological, immunological and genetic studies of CD30+ anaplastic large cell lymphoma of B-cell type; association with Epstein-Barr virus in a Japanese population

The clinicopathological features, the immunophenotype, and the presence of Epstein-Barr virus (EBV)-associated genomes and gene products were examined in 17 cases of CD30+ anaplastic large cell lymphoma (ALCL) of B-cell type. Microscopically, the 17 cases were divided into ten cases of the monomorphic type and seven cases of the pleomorphic type. EBV was detected in 6 of 17 cases (38 per cent) by RNA in situ hybridization (ISH) with EBV-encoded RNA (EBER1). EBER1+ cases consisted of two cases (20 per cent) of the monomorphic type and four cases (57 per cent) of the pleomorphic type. The five EBER1+ cases showed clonality of the EBV genome by Southern blotting, consistent with the presence of EBV in a monoclonal proliferation. The EBV-encoded latent membrane protein 1 (LMP1) was found in all six EBER1+ cases and EBV-encoded nuclear antigen 2 (EBNA2) was present in two cases by immunohistochemistry. No expression of LMP1 or EBNA2 was observed in the EBER1-cases. The EBER1+ cases had a tendency for a more favourable prognosis than the EBER1-cases. It is concluded that EBV has an association with CD30+ ALCL of B-cell type in the Japanese population studied, and especially with the large pleomorphic type. EBV infection may play a pathoaetiological role and may influence clinical behaviour.

Chemiluminescence enzyme immunoassay using bacterial magnetic particles

A novel chemiluminescence enzyme immunoassay using bacterial magnetic particles (BMPs) has been developed for highly sensitive and rapid detection of immunoglobulin G. Antibody was immobilized onto BMPs using the heterobifunctional reagents sulfosuccinimidyl 6-[3'-(2-pyridyldithio) propionamido]hexanoate (sulfo-LC-SPDP) and sulfosuccinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate (sulfo-SMCC). For the highly sensitive immunoassay method using these BMPs, a good relationship was obtained between the luminescence intensity and mouse IgG concentration in the range of 1-10(5) fg/mL. Furthermore, in order to reduce assay time and to simplify operations, a rapid chemiluminescence enzyme immunoassay method has been developed. The rapid method was completed in 10 min. A linear relationship was obtained between the luminescence and mouse IgG concentration in the range of 10-1000 ng/mL.

Arthroscopic posterior cruciate ligament reconstruction using hamstring tendons: one-incision technique with Endobutton

The one-incision surgical technique using autogenous hamstring tendons with Endobutton (Acufex Microsurgical Inc. Mansfield, MA) femoral end fixation for posterior cruciate ligament reconstruction is described. This technique avoids a second incision on the femoral side, and is adaptable to various graft materials (autogenous or allogeneic bone-patellar tendon-bone, hamstring, or Achilles tendon.

Specific detection of deleted mitochondrial DNA by in situ hybridization using a chimera probe

We report a new method for the specific detection of the mutant mitochondrial DNA (mtDNA) that contains the 4977-bp deletion. We designed an oligonucleotide probe that was designated the 'ATP8/ND5 Chimera' probe: its 5'- and 3'-portions correspond to the ATP8 gene and the ND5 gene, respectively, and its middle portion includes the 13-bp direct repeat sequence that flanks the 4977-bp deletion. By Southern blot analysis, this chimeric probe specifically detected the deleted mtDNA, even in the presence of both normal mtDNA and other mtDNA deletions. The specificity of the probe was further confirmed by in situ hybridization of muscle fibers from patients with Kearns-Sayer syndrome who carry the deleted DNA in the heteroplasmic state. The deleted mtDNA was markedly accumulated in cytochrome-c oxidase (COX)-deficient ragged-red fibers. In tissues where multiple deleted mtDNAs were detected, such as muscle tissues from a patient with myotonic dystrophy and from an aged individual, the in situ hybridization detected a small number of muscle fibers that contained the deleted mtDNA. These results indicate that in situ hybridization using this chimera probe is a useful and specific method for detecting a small amount of deleted mtDNA.

Formation of crossline as a fluorescent advanced glycation end product in vitro and in vivo

Crossline is one of the major advanced glycation end products resulting the reaction mixture of free amino group(s) such as epsilon-one in lysine with D-glucose in vitro. To study crossline formation on proteins in vitro and in vivo, polyclonal antiserum to the crossline hapten was prepared. This antiserum reacted with bovine and human serum albumin that had been modified by prolonged incubation with glucose as well as with crossline itself. Antisera did not react with unmodified serum albumin or the other Maillard-related compounds. Crossline was formed in a time-dependent manner when a mixture of six different proteins was incubated with glucose at pH 7.2 or 9.0. Crossline levels could be measured in rat lens proteins and the levels increased with age. The crossline content of lens proteins in diabetic rats was more than two-fold higher than that of age-matched controls. Results of this study suggest that most proteins containing advanced glycation end products have crossline-like structures. Measurement of crossline-like structures in biological specimens may provide an index of aging and of the development of diabetic complications.

Cephalometric comparison of craniofacial morphology between primary bone grafted and nongrafted complete unilateral cleft lip and palate adults

The effect of primary bone grafts on craniofacial growth was evaluated in adult patients with complete unilateral cleft lip and palate (UCLP). The subjects were 18 UCLP patients with primary bone grafts and a control group of 36 UCLP patients without bone grafts. The former received primary transplantation of autogenous rib bone simultaneously with primary cheiloplasty by the same surgeon between 1963 and 1969. Frontal and lateral cephalograms taken after 16 years of age were traced. Skeletal landmarks were identified on them, and their x,y-coordinates were digitized. The effects of gender and/or primary bone graft on the craniofacial morphology were tested by ANOVA using 21 angles, 8 breadths, 13 distances, and 2 ratios. Nasal cavity breadth was wider in the primary bone grafted group. However, the anterior maxilla in that group was more upward and retruded than that in the nongrafted group. The primary bone grafted group was divided into two subgroups based on the overjet of the incisors: group N = normal overjet; group C = anterior cross-bite. There was no difference in the maxilla between groups N and C. However, the mandible in group C was more anterior and superior than in group N. In conclusion, primary bone graft may impede maxillary horizontal and vertical growth to a certain degree, and severe anterior cross-bite in primary bone grafted subjects may be brought about by mandibular closure.

[A 63 year-old man with progressive gait disturbance and dysarthria]

We report a 63-year-old man with progressive gait disturbance and dysarthria. The patient was apparently well until the age of 62 (February, 1990) when he noted unsteadiness of gait. Two months later, dysarthria appeared. He was admitted to Juntendo Izunagaoka Hospital on April 23, 1990. Neurologic examination revealed a mentally sound man with normal higher cerebral functions. Cranial nerves were unremarkable except for scanning speech. His gait was ataxic with positive Romberg sign. No motor weakness was noted, however, he had hypotonia and cerebellar ataxia. Deep tendon reflexes were retained and the plantar response was flexor. Pain, touch and vibration senses were diminished in the distal parts of the lower extremities. Laboratory examination revealed a 2.5 cm mass in the left lung field. Cranial MRI revealed a small T1-low and T2-high signal intensity lesion in the left temporal lobe. Abdominal CT scan revealed multiple low density lesions in the liver. His subsequent course was complicated by progressive deterioration in his gait and loss of deep tendon reflexes. He expired on November 24, 1990. The patient was discussed in the neurological CPC and the chief discussant arrived at the conclusion that the patient had anti-Hu associated paraneoplastic encephalomyelitis and sensory neuropathy. Some other participants thought that the patient had carcinomatous cerebellar degeneration. Postmortem examination revealed a 4x4 cm mass lesion involving the left S4-S5 segments. Histologic examination of the tumor was small cell carcinoma. Many metastatic foci were found in the liver. The cerebral hemispheres were unremarkable except for a small wedge-shaped tissue defect in the left temporal lobe which appeared to have been caused by old head trauma which the patient had received. The cerebellar vermis showed slight enlargement of cortical sulci, however, the cerebellar hemispheres appeared unremarkable. Upon histologic examination, marked loss of Purkinje cells was noted, particularly in the cerebellar anterior lobe. The dentate nucleus showed slight cell loss with increase in fat granule cells. The inferior olive was normal. The histologic characteristics were consistent with the pathologic diagnosis of carcinomatous cerebellar degeneration. No evidence of limbic encephalitis was seen. The peripheral nerve was not examined.

PIG-B, a membrane protein of the endoplasmic reticulum with a large lumenal domain, is involved in transferring the third mannose of the GPI anchor

Many eukaryotic cell surface proteins are bound to the membrane via the glycosylphosphatidylinositol (GPI) anchor that is covalently linked to their carboxy-terminus. The GPI anchor precursor is synthesized in the endoplasmic reticulum (ER) and post-translationally linked to protein. We cloned a human gene termed PIG-B (phosphatidylinositol glycan of complementation class B) that is involved in transferring the third mannose. PIG-B encodes a 554 amino acid, ER transmembrane protein with an amino-terminal portion of approximately 60 amino acids on the cytoplasmic side and a large carboxy-terminal portion of 470 amino acids within the ER lumen. A mutant PIG-B lacking the cytoplasmic portion remains active, indicating that the functional site of PIG-B resides on the lumenal side of the ER membrane. The PIG-B gene was localized to chromosome 15 at q21-q22. This autosomal location would explain why PIG-B is not involved in the defective GPI anchor synthesis in paroxysmal nocturnal hemoglobinuria, which is always caused by a somatic mutation of the X-linked PIG-A gene.

An epidermal growth factor receptor/Jak2 tyrosine kinase domain chimera induces tyrosine phosphorylation of Stat5 and transduces a growth signal in hematopoietic cells

The Jak family of tyrosine kinases and the Stat family of transcription factors have been implicated in transducing signals from the hematopoietic growth factor receptors. To explore the role played by a member of the Jak family, Jak2, in hematopoietic cell growth signaling, we constructed a chimeric cDNA coding for the Jak2 tyrosine kinase domain linked to the extracellular and transmembrane regions of the epidermal growth factor (EGF) receptor (EGFR) and expressed the chimera in an interleukin (IL)-3-dependent cell line, 32D. When deprived of IL-3, EGF prevented apoptosis of the transfected cells, induced dose-dependent proliferation, and supported long-term growth. EGF stimulation of the transfectants induced dose-dependent tyrosine phosphorylation of the EGFR/Jak2 chimera and Stat5, which correlated with the EGF dose dependence of cell proliferation. On the other hand, EGF did not induce tyrosine phosphorylation of other factors implicated in cytokine receptor signaling, including the IL-3 receptor beta subunit, Jak kinases, Stat proteins other than Stat5, Shc, Syp, and mitogen-activated protein kinases. These results suggest that the activation of Jak2 may be sufficient for transducing a growth signal in hematopoietic cells by activating the Stat5 pathway or previously unidentified signaling pathways. In addition, because EGF induces homodimerization of the EGFR to activate its tyrosine kinase activity, the present study, which shows EGF-dependent activation of the EGFR/Jak2 chimera, implies that Jak2 may also become activated by homodimerization.

Human calcitonin has the same inhibitory effect on osteoclastic bone resorption by human giant cell tumor cells as salmon calcitonin

Human calcitonin (hCT) has been reported to have a less hypocalcemizing effect on rats and to have a lower binding affinity for the receptor of mouse osteoclasts than salmon CT(sCT). In this study we comparatively examined the effect of hCT and sCT on osteoclastic bone-resorbing activity of unfractionated cells obtained from human giant cell tumor of bone and from rabbit and mouse long bones. We found that hCT had the same inhibitory effect as sCT on the bone-resorbing activity of human and rabbit osteoclastic cells, but a different one on that of mouse cells. These results indicate that the activity of drugs should be assayed using human cells if possible.

Suppression of inducible nitric oxide synthase mRNA expression by tryptoquinone A

Triptoquinone A (TQA), which is an anti-inflammatory constituent in plants, was studied for its suppressive effect on nitric oxide production by LPS. TQA significantly suppressed smooth muscle relaxation and increase in cyclic GMP levels by nitric oxide (NO) in an L-arginine-induced relaxation experiment. The mechanistic studies showed that TQA did not directly inhibit NO radicals and inducible nitric oxide synthase (iNOS) enzyme but suppressed IL-1 beta and iNOS mRNA expression by LPS. The suppression level of iNOS gene expression by TQA was comparable to that by dexamethasone. TQA may be a useful candidate for the development of a drug as a potent inhibitor of iNOS gene over-expression.

Uterine leiomyosarcoma metastasis to the skull--case report

A 54-year-old female presented with a rare uterine leiomyosarcoma metastasis to the skull appearing as a gross mass beneath her scalp. She had no neurological or other physical symptoms on admission. Computed tomography and magnetic resonance imaging demonstrated an enhanced dumbbell-shaped mass at the mid-frontal region beneath the scalp. The tumor was totally removed with normal surrounding bone and dura. The histological diagnosis was leiomyosarcoma. Her postoperative course was uneventful, and she received adjuvant chemotherapy. However, multiple distant bone metastases developed 1 year later. Immediate and radical resection of such tumors is recommended.

Somatic cell mutations at the glycophorin A locus in erythrocytes of atomic bomb survivors: implications for radiation carcinogenesis

To clarify the relationship between somatic cell mutations and radiation exposure, the frequency of hemizygous mutant erythrocytes at the glycophorin A (GPA) locus was measured by flow cytometry for 1,226 heterozygous atomic bomb (A-bomb) survivors in Hiroshima and Nagasaki. For statistical analysis, both GPA mutant frequency and radiation dose were log-transformed to normalize skewed distributions of these variables. The GPA mutant frequency increased slightly but significantly with age at testing and with the number of cigarettes smoked. Also, mutant frequency was significantly higher in males than in females even with adjustment for smoking and was higher in Hiroshima than in Nagasaki. These characteristics of background GPA mutant frequency are qualitatively similar to those of background solid cancer incidence or mortality obtained from previous epidemiological studies of survivors. An analysis of the mutant frequency dose response using a descriptive model showed that the doubling dose is about 1.20 Sv [95% confidence interval (CI): 0.95-1.56], whereas the minimum dose for detecting a significant increase in mutant frequency is about 0.24 Sv (95% CI: 0.041-0.51). No significant effects of sex, city or age at the time of exposure on the dose response were detected. Interestingly, the doubling dose of the GPA mutant frequency was similar to that of solid cancer incidence in A-bomb survivors. This observation is in line with the hypothesis that radiation-induced somatic cell mutations are the major cause of excess cancer risk after radiation exposure. Furthermore, the dose response was significantly higher in persons previously or subsequently diagnosed with cancer than in cancer-free individuals. This may suggest an earlier onset of cancer due to elevated mutant frequency or a higher radiation sensitivity in the cancer group, although the possibility of dosimetry errors should be considered. The findings obtained in the present study suggest that the GPA mutant frequency may reflect the cancer risk among people exposed to radiation.

Inducible osteonecrosis in a rabbit serum sickness model: deposition of immune complexes in bone marrow

We established inducible osteonecrosis in a rabbit serum sickness model. Osteonecrosis with marrow necrosis could be induced by the intravenous injection of horse serum in two doses separated in time by a period of three weeks. In this model, osteonecrosis could be successfully produced in rabbit femoral metaphysis. The incidence of marrow necrosis was 45% (9 of 20 rabbits) and trabecular necrosis occurred in 6 of 20 rabbits (30%) at 7 days after the second injection of the horse serum. In bone marrow of the femoral metaphysis, extravasation of erythrocytes and the formation of micro-thrombi in arterioles were often observed in an early stage of the present model and both findings correlate well each other (p = 0.0001). Immune complexes could be demonstrated using immunohistochemistry in bone marrow of the femoral metaphysis as well as in glomeruli of the kidney. Extravasation of erythrocytes in bone marrow of the femoral metaphysis was observed in 8 of 12 (67%) cases with immune complex deposition in the sinusoidal space of the femoral metaphysis and in 12 of 21 (57%) cases with immune complex deposition in glomeruli of the kidney. Immune complex deposition both in the sinusoidal space of femoral bone marrow (p = 0.0385) and in glomeruli of the kidney (p = 0.0209) closely related to extravasation of erythrocytes and microthrombi in arterioles in the early stage of this model. Early microcirculatory injury (extravasation of erythrocytes and microthrombi in arterioles) adjacent to osteonecrosis could be induced by immune complex deposition in femoral bone marrow and might be predictable characteristics for the inducible osteonecrosis in the present serum sickness model. The important findings in this study were that early microcirculatory injury was closely related to the deposition of immune complexes in femoral bone marrow, and that early microcirculatory injury associated with immune complex deposition was located close to osteonecrotic regions.