Lack of an association between cystatin C gene polymorphisms in Japanese patients with Alzheimer's disease

Associations between polymorphisms of the cystatin C gene (CST3) at 5' flanking region and exon 1 in Caucasian patients with late onset AD and exon 1 in a US study of late onset AD have been reported. Clinically diagnosed Japanese patients with AD and Japanese normal control subjects were assessed for the presence of polymorphisms of CST3. The authors could not confirm the previously reported association between CST3 polymorphisms and AD in Japan. Age had no effect on the CST3 genotype.

Glypican-1 is overexpressed in human breast cancer and modulates the mitogenic effects of multiple heparin-binding growth factors in breast cancer cells

Glypicans are a family of glycosylphosphatidylinositol-anchored cell surface heparan sulfate proteoglycans implicated in the control of cellular growth and differentiation. Here we show that glypican-1 is strongly expressed in human breast cancers, whereas expression of glypican-1 is low in normal breast tissues. In contrast, the expression of glypican-3 and -4 is only slightly increased in breast cancers by comparison with normal breast tissues, and glypican-2 and -5 are below the level of detection by Northern blotting in both normal and cancer samples. Treatment of MDA-MB-231 and MDA-MB-468 breast cancer cells with phosphoinositide-specific phospholipase-C abrogated the mitogenic response to two heparin-binding growth factors, heparin-binding epidermal growth factor-like growth factor and fibroblast growth factor 2. Stable transfection of these cells with a glypican-1 antisense construct markedly decreased glypican-1 protein levels and the mitogenic response to the same heparin-binding growth factors, as well as that to heregulin alpha, heregulin beta, and hepatocyte growth factor. Syndecan-1 was also expressed at high levels in both breast cancer tissues and breast cancer cells when compared with normal breast tissues. There was a good correlation between glypican-1 and syndecan-1 expression in the tumors. However, clones expressing the glypican-1 antisense construct did not exhibit decreased syndecan-1 levels, indicating that loss of responsiveness to heparin-binding growth factors in these clones was not due to altered syndecan-1 expression. Furthermore, 8 of 10 tumors with stage 2 or 3 disease exhibited high levels of glypican-1 by Northern blot analysis. In contrast, low levels of glypican-1 mRNA were evident in 1 of 10 tumors with stage 2 or 3 disease and in 9 of 10 tumors with stage 1 disease. Taken together, these data suggest that glypican-1 may play a pivotal role in the ability of breast cancer cells to exhibit a mitogenic response to multiple heparin-binding growth factors and may contribute to disease progression in this malignancy.

Influence of interleukin-1beta gene polymorphism on age-at-onset of spinocerebellar ataxia 6 (SCA6) in Japanese patients

An inverse correlation is observed between the expanded CAG repeat number and age-at-onset of spinocerebellar ataxia 6 (SCA6). To detect another modifying genetic factor for SCA6, we studied polymorphisms in the genes for interleukin (IL)-1beta and tumor necrosis factor in 122 Japanese patients with SCA6. No contribution of these polymorphisms to the variance in disease onset was observed by regression analysis or by ANOVA. The IL-1beta promoter polymorphism, however, significantly affected the age-at-onset, when adjusted for the CAG repeat number as a covariate (P=0.0004, by ANCOVA), suggesting that IL-1beta may be a genetic factor other than the SCA6 gene that modifies the age-at-onset of the disease.

Cervico-mediastinal bronchogenic cyst occurring in the prenatal period: report of a case

We experienced a case of cervico-mediastinal bronchogenic cyst in which a cervical cystic mass was detected by prenatal ultrasonography. On prenatal ultrasound, a unilocular, well-defined and hypoechoic mass was detected in the fetal neck. The baby was born by a normal vaginal delivery at 40 weeks of gestation, and had no respiratory distress. Radiological investigations demonstrated a cyst in the cervico-mediastinal region, which displaced the trachea to the left. At the age of 32 days, an elective resection was easily performed through a right inferior collar incision after first aspirating the contents of the cyst. Prenatal sonography showing abnormal findings is effective for identifying cysts in the perinatal period and allows for the timely resection of such cysts before respiratory distress occurs.

Hemorrhagic gastric carcinoma in an acromegalic patient

A rare case of hemorrhagic gastric carcinoma in an acromegalic patient is reported. A 79-year-old Japanese man was referred to our hospital with diagnoses of upper gastrointestinal hemorrhage and angina pectoris. This patient showed typical clinical features of acromegaly, with increased serum growth hormone (GH) and insulin-like growth factor I (IGF-I) level. A high titer of serum anti-Helicobacter pylori (H. pylori) IgG was also observed. After percutaneous transluminal coronary angioplasty treatment for stenosis of the right coronary artery, the patient underwent distal gastrectomy. Gastric cancer was Type 2 macroscopically and was diagnosed histologically as a papillary and well to moderately differentiated tubular adenocarcinoma. Reverse transcription-polymerase chain reaction analysis estimated that the amount of IGF-I receptor mRNA expression in the gastric cancer tissue was 1.6 times higher than that in the adjacent atrophic mucosa, whereas the amount of IGF-I mRNA expression in the cancer tissue was only half that in the atrophic mucosa. Both the stimulatory effects of GH and/or IGF-I on cell proliferation and H. pylori infection in gastric tumorigenesis may have been responsible for the development and growth of gastric carcinoma in this patient.

Multifocal micronodular pneumocyte hyperplasia and lymphangioleiomyomatosis in tuberous sclerosis with a TSC2 gene

A 45-year-old woman with a long-standing diagnosis of tuberous sclerosis (TSC) is presented. She has multifocal micronodular pneumocyte hyperplasia (MMPH) and lymphangioleiomyomatosis (LAM) of the lung, together with the detection of TSC2 gene mutation. During surgery for spontaneous pneumothorax, an open-lung biopsy was performed. Micronodules were well defined, measuring approximately 4 mm in diameter. These MMPHs were histologically composed of papillary proliferation of Type II pneumocytes, with positive immunoreactivity of keratin and surfactant apoprotein. The cystlike spaces, with dilatation and destruction of air spaces, were diffusely formed, and the walls were composed of the spindle cells. Such LAM showed positive immunoreactivity for HMB-45 (a monoclonal antibody specific for human melanoma) and tuberin (the gene product of TSC2). On germline mutation analysis using leukocytes of the present patient, a TSC2 gene mutation was confirmed as a deletion of G (or g) on Exon 9 by polymerase chain reaction-single-strand conformational polymorphism. However, no mutation was detected in her son. With microdissection analysis using paraffin-embedding lung tissues, LOH of the TSC2 gene preliminarily was detected in a LAM lesion but not in MMPH. It is suggested that MMPH, in addition to LAM, could be another pulmonary lesion in TSC patients and that the detection of TSC2 and/or TSC1 gene could essentially be useful for the pathogenesis of MMPH and LAM in TSC patients.

Hemodynamics in the left gastric vein after endoscopic ligation of esophageal varices combined with sclerotherapy

BACKGROUND AND METHODS

We examined the changes in portal hemodynamics after endoscopic variceal ligation (EVL) combined with endoscopic injection sclerotherapy (EIS) in relation to post-treatment relapse. The present study included 93 patients who underwent EVL-EIS combination therapy. Portal hemodynamics were examined by Doppler ultrasonography and percutaneous transhepatic portography (PTP).

RESULTS

Therapy with EVL-EIS resulted in the complete disappearance of varices in 89 of 93 patients. Cumulative relapse-free rates (Kaplan-Meier method) were 75.8 and 50.2%, respectively, 1 and 3-5 years after treatment. At the end of treatment, the flow in the left gastric vein was examined by Doppler ultrasonography. In 50 of 63 patients, the flow remained hepatofugal. In 23 of these patients, PTP was performed at the end of treatment; selective left gastric venography did not reveal any palisade zone vessels or varices. However, fine blood vessels were seen around the lower esophagus in nine patients, only the paraesophageal vein was found in 10 patients and these two findings were present in four patients, indicating that collateral blood flow remained in the lower esophagus in 13 of 23 patients. These findings suggest that frequent relapse of varices results from insufficient blockage of blood flow from the left gastric vein to the lower esophagus. However, in patients with a patent paraesophageal vein, long-term effects obtained by EVL-EIS combination therapy were satisfactory.

CONCLUSIONS

The pattern of the development of collateral left gastric veins represents important hemodynamic changes that predict the long-term prognosis of patients after treatment.

Primary non-Hodgkin's lymphoma of the uterine cervix

We present a patient with primary malignant lymphoma of the uterine cervix, which is extremely rare. She had a complete remission with a combination of chemotherapy and radiotherapy. Measurement of the serum soluble interleukin-2 receptor level was a useful index of the effectiveness of treatment.

Clinical significance of numerical aberrations on chromosome 17 in uterine cervical and endometrial neoplasias

In order to determine the clinical significance of numerical aberrations on chromosome 17 in uterine cervical and endometrial neoplasias, we investigated 140 cell specimens obtained from the uterine cervix and endometrium using the fluorescence in situ hybridization (FISH) method. These specimens consisted of ten normal cervical epithelium (NCE), 16 cervical intraepithelial neoplasias (CIN 1), 15 CIN 2, 35 CIN 3, 11 early invasive squamous cell carcinoma of the uterine cervix (early invasive SCC), 11 invasive SCC, 13 normal endometrium (NE), 17 endometrial hyperplasias (EH), and 12 endometrial ademocarcinomas (EA). After Papanicolaou staining on these specimens was decolorized, FISH was performed using chromosome 17 specific repetitive DNA probes. Signals of centromere of chromosome 17 in marked atypical cells were counted using a fluorescence microscope. There was a significant difference in the rate of cells with one signal on chromosome 17 between CIN 1 (7.1+/-0.7%) or 2 (7.0+/-0.5%) and CIN 3 (12.6+/-0.9%) (p<0.01), and also between CIN 3 and early invasive SCC (19.6+/-1.0%) (p<0.01). The rate of cells with three signals was significantly increased when the uterine cervical lesions were progressive to CIN 3 (p<0.01). Cells with five or more signals occurred only in early invasive SCC and invasive SCC. There was a significant difference in the rate of cells with three signals between EH (4.8+/-0.6%) and EA (11.4+/-2.1%) (p<0.05). Cells with five or more signals occurred only in EA. Examination of the numerical aberrations on chromosome 17 in uterine cervical and endometrial neoplasias has been suggested to be useful as an additional method for the differential diagnosis of these lesions.

Genetic studies in Parkinson's disease with an alpha-synuclein/NACP gene polymorphism in Japan

Dinucleotide repeat polymorphism has been observed in the promoter of the alpha-synuclein (alpha-SYN)/NAC precursor protein (NACP) gene. Alpha-SYN/NACP allele 3 (described by Xia et al. (Ann. Neurol., 40 (1996) 207), equivalent to allele 1 described by Krüger et al. (Ann. Neurol. 45 (1999) 611) is reported to be significantly more frequent among patients with sporadic Parkinson's disease (sPD) than controls. In this study, we genotyped the same alpha-SYN/NACP polymorphism in Japanese sPD patients and healthy controls, but found that any aliele showed no significant difference between the two groups.

Multielectron excitations probed by helicity-modulation XMCD at K-edge in 3d transition metal compounds

Multielectron excitations (MEE) have been investigated using X-ray magnetic circular dichroism (XMCD) at the K-edge in 3d transition metal compounds. In the range of 50-70 eV above the absorption edge, a dichroic signal that is associated with MEE was identified. This phenomenon is thought to occur due to the super Coster-Kronig transition described as the final states (1s)1(3p)5(3d)n+2 resulting from the 3p --> 3d transitions. In order to verify this interpretation, XMCD measurements using the helicity-modulation method and calculations of the dichroic spectrum were performed based on this super Coster-Kronig transition.

Study of magnetic materials using helicity-modulated X-ray magnetic circular dichroism

A new helicity-modulation technique has been applied for recording X-ray magnetic circular dichroism (XMCD) at the K-absorption edge in transition-metal magnetic materials. This technique enables the measurement of the XMCD spectrum with high precision and under extreme conditions. The refined spectrum is presented at the Fe K edge for pure Fe, Fe4N and Co-ferrite. The method is very promising for site-assignment of magnetic cations and for detailed investigation of the magnetic states in a local environment. In Mn3MC perovskites, the dependence of the Mn K-edge XMCD spectrum on temperature and magnetic field demonstrates that the orbital moments are closely associated with the magnetic phase transition. New information obtained from the refined spectrum and novel phenomena observed in temperature and field variations is presented.

Variation of XMCD spectrum with temperature at R L2,3-edges in R3Fe5O12 (R=Gd and Er)

The variation of X-ray magnetic circular dichroism (XMCD) with temperature has been measured at R L2,3-edges in R3Fe5O12 (R=Gd and Er). A drastic change in the spectral profile has been observed at low temperatures. The variation of XMCD peak intensity, corrected by the contribution of Fe with temperature, is in agreement with the magnetization of R sublattice. The results suggest that Fe 3d polarization plays an important role to produce the R L2,3-edges XMCD spectrum.

[A case of polyarteritis nodosa presenting as a mass in scrotum]

A 16-year-old boy with a painful tumor in the left scrotum was referred to our department. CT scans showed a low density area in the left testis, so we diagnosed a left testicular tumor and performed left inguinal orchiectomy. Histological examination revealed polyarteritis nodosa (PN) of the testis and epididymis. Systemic examination revealed no other evidence of PN. Although induration developed in the right epididymis after the operation, it resolved with steroid therapy. The patient is currently asymptomatic and is being followed at our clinic. The pathogenesis and management of this rare condition are discussed.

Magnetic circular dichroism of 3d5/2 --> 2p3/2 resonant inelastic X-ray scattering at the Ho L(III)-edge in Ho3Fe5O12

Magnetic Circular Dichroism (MCD) of Resonant Inelastic X-ray Scattering (RIXS) of 3d(5/2) --> 2p(3/2) decay (Ho Lalpha1) was measured at the Ho L(III)-edge in Ho3Fe5O12. The MCD-RIXS, in which the intermediate state has the 2p4f(n+1) configuration due to the quadrupolar transition of 2p --> 4f, was also observed at the pre-edge region of the Ho L(III)-edge. The obvious superposition of two peaks, which comes from the high-energy off-resonant Raman scattering and the fluorescence, could be found in both the RIXS and the MCD-RIXS when the energy of the incoming X-ray was 7eV higher than the white line. The dependence of the integration of the MCD-RIXS spectra on the incident x-ray energy could roughly reproduce the MCD of X-ray absorption spectra (XAS).

Mn K-edge XMCD in Mn3MC (M=Zn and Ga) perovskite

Mn3MC (M=Zn and Ga) perovskite has attracted interest because of a variety of magnetic phase transitions. In this work, we measure temperature and magnetic field dependence of X-ray magnetic circular dichroism (XMCD) at Mn K-edge and discuss effect of second constituent metal on the magnetic states of Mn atoms. The spectrum in Mn3ZnC is characterized by a dispersion-type profile. In Mn3GaC, intensity of the positive peak at the edge is drastically reduced. The difference originates in charge transfer from Zn or Ga to Mn atoms. Temperature and magnetic field variations of the Mn K-edge XMCD spectrum suggest that orbital magnetic moments are closely related to the magnetic phase transition.

Long-term production of erythropoietin after electroporation-mediated transfer of plasmid DNA into the muscles of normal and uremic rats

The anemia associated with chronic renal failure is one of the best target diseases for erythropoietin (Epo) gene transfer. We previously reported a short-term (1 month) study of continuous rat Epo delivery by muscle-targeted gene transfer of plasmid DNA expressing rat Epo (pCAGGS-Epo) using in vivo electroporation in normal rats. Here, we performed a long-term pharmacokinetic study of continuous Epo delivery by this method in normal rats and uremic five-sixths nephrectomized rats. In normal rats, Epo gene expression and sufficient erythropoiesis occurred with Epo gene transfer in a dose-dependent manner, and persisted for at least 11 weeks. Repeated administration of the plasmid DNA effectively produced erythropoiesis. Similar erythropoiesis was observed in the uremic rats, and persisted for more than 15 weeks. Both normal and uremic rats showed a significant decrease in platelet count. Moreover, the uremic rats showed Epo-induced hypertension, which is the major side-effect of recombinant human Epo. These results demonstrate that muscle-targeted pCAGGS-Epo transfer by in vivo electroporation is a useful procedure for the long-term continuous delivery of Epo in both normal and uremic rats.

Electronic states in Cu2MnX (X=Al, In, and Sn) Heusler alloy studied by XMCD and multiple scattering calculations

X-ray magnetic circular dichroism (XMCD) has been measured at Mn and Cu K-edge in Cu2MnX (X=Al, In, and Sn) Heusler alloy. The Mn K-edge spectrum shows a dispersion-type profile and the Cu K-edge resembles the Mn spectrum, which suggests that polarization of the p unoccupied bands originates commonly in Mn 3d states. To reproduce the observed spectrum by full multiple scattering calculations. Madelung potential has been taken into account. Charge redistribution is an important factor for the electronic structure in Cu2MnX Heusler alloy.

Diagnostic significance of tau protein in cerebrospinal fluid from patients with corticobasal degeneration or progressive supranuclear palsy

Distinguishing corticobasal degeneration (CBD) from progressive supranuclear palsy (PSP) is clinically and pathologically difficult, and a useful biological marker to discriminative these two diseases has been a subject of clinical interest. In the present study, we assessed tau protein levels in cerebrospinal fluids by sandwich ELISA to distinguish CBD from PSP. The subjects consisted of 27 cases of CBD, 30 cases of PSP, and 36 healthy controls (CTL). The tau values in CBD were significantly higher than those in PSP (P<0.001) and those in CTL (P<0.001). The assay of CSF tau provided diagnostic sensitivity of 81.5% and specificity of 80.0% between CBD and PSP according to receiver-operating characteristic (ROC) curve analysis. When values were compared separately with respect to stage of the disease, differences in the values for moderate CBD vs. moderate PSP had the greatest significance (P<0.001 sensitivity 92.3%, specificity 100.0%), followed by cases of mild CBD and PSP (P<0.005, sensitivity 100.0%, specificity 87.5%). The values in severe CBD and PSP were not significantly different (P=0.07, sensitivity 100%, specificity 75.0%). Using data obtained from a larger number of disease cases, we confirmed our previous findings that tau protein levels in cerebrospinal fluids in patients with CBD are significantly higher than those in patients with PSP. Because tau protein levels in cerebrospinal fluids are significantly higher in early CBD cases than in early PSP cases, measurement of tau protein levels in cerberospinal fluids may be useful for the differential diagnosis of early CBD from early PSP.

Citrullinemia type II in a 64-year-old man with fluctuating serum citrulline levels

We describe a 64-year-old man with 'citrullinemia type II' whose serum citrulline levels fluctuated between normal and abnormally high during episodic manifesting periods. Elevations of the serum threonine/serine ratio and pancreatic secretory trypsin inhibitor level are very useful diagnostic markers. Our patient's cerebrospinal fluid citrulline level was also elevated, and T1-weighted magnetic resonance images revealed high-intensity signals at the bilateral internal capsule and the cerebral peduncles. Single-photon emission computed tomography of his brain showed reduced bilateral temporal lobar blood flow. Even if the serum citrulline level is within the normal range, citrullinemia should be considered in adult patients without primary liver dysfunction who show episodic consciousness disturbance, psychotic symptoms or both.

Vaccination with calpain induces a Th1-biased protective immune response against Schistosoma japonicum

A large subunit of calpain, a calcium-activated neutral proteinase, from Schistosoma japonicum was cloned and expressed in Escherichia coli. When BALB/c mice were immunized with purified recombinant calpain (r-calpain) emulsified in complete Freund's adjuvant, a significant reduction in the number of recovered worms and also in egg production per female worm was observed (P<0.01). Spleen cells of the immunized mice showed enhanced production of gamma interferon (IFN-gamma) by activated CD4(+) T cells. Considering our observation of elevated expression of inducible nitric oxide synthase mRNA in immunized mice, r-calpain-induced IFN-gamma seemed to upregulate the production of nitric oxide by macrophages and subsequently mediated the killing of schistosomulae in the lung. On the other hand, spleen cells of immunized mice showed only faint interleukin-4 production in response to r-calpain in vitro, suggesting that immunization with r-calpain alters the Th1-Th2 balance in murine hosts even during a Th2-promoting S. japonicum infection. Furthermore, histopathological study of the livers of immunized mice showed that granulomas formed around eggs were diminished in both size and number. Egg production by female worms was clearly decreased in immunized mice, suggesting that r-calpain also has antifecundity effects. Taken together, these results point to S. japonicum calpain as a potential vaccine candidate for both worm killing and disease prevention, possibly through the induction of a strong Th1-dominant environment in immunized mice.

Low serum lipids suggest severe bone marrow failure in children with aplastic anemia

BACKGROUND

Significantly low serum lipid levels are occasionally seen at the time of diagnosis in children with aplastic anemia (AA). The aim of the present study was to clarify the pathologic and clinical significance of pretreatment serum lipid levels in AA.

METHODS

A questionnaire seeking precise data about AA in pediatric patients, including the initial laboratory data at the time of onset of AA and the clinical course of these patients, was sent to 18 institutes in Japan; 13 institutes responded to the questionnaire. In this retrospective study, data concerning hematologic examination and serum lipids were available for analysis in 127 children with AA. Serum lipoprotein patterns were analyzed using conventional agarose electrophoresis in eight patients. In order to elucidate the cause of hypolipidemia in AA, we assayed serum macrophage colony stimulating factor (M-CSF), which is well known to have apparent cholesterol-lowering activity, by using an enzyme-linked immunosorbent assay in seven patients with hypocholesterolemia and compared the results with those obtained in patients with iron-deficiency anemia (IDA).

RESULTS

We found that pretreatment total cholesterol (TC) and triglyceride levels in the serum correlated well with counts of both nucleated cells and hemopoietic cells in the bone marrow (BM) and were inversely correlated with the lymphocyte ratio in both the BM and peripheral blood. Patients with serum TC lower than 150 mg/dL showed a poor response to any form of therapy except BM transplantation. There was no difference in the serum lipoprotein patterns between the controls and patients examined. The serum M-CSF level was significantly higher in patients with TC levels lower than 150 mg/dL compared with controls.

CONCLUSIONS

These results indicate that the pretreatment serum lipid level may reflect hematopoietic activity within the BM and can help to predict the therapeutic response of each case of AA to treatment with immunosuppressive drugs, corticosteroids and anabolic steroids. These results also indicate that M-CSF may be one of the contributing causes of the hypocholesterolemia that occurs in both AA and IDA.

Tumor necrosis factor alpha gene G-308A polymorphism, insulin resistance, and fasting plasma glucose in young, older, and diabetic Japanese men

In obese subjects, the levels of tumor necrosis factor alpha (TNF-alpha) expression and protein synthesis in adipocytes are increased. A recent study of Caucasians suggested that the TNF-alpha gene promoter region polymorphism at position -308 influences insulin resistance and percent body fat and increases serum leptin levels, although conflicting data are also reported. The present study was performed to investigate the relationship between this polymorphism and the body mass index (BMI), blood pressure, glucose and lipid profiles, and serum leptin in 122 healthy young men aged 21 to 29, 177 older men aged 45 to 65, and 71 type 2 diabetic male patients aged 42 to 78. The BMI, blood pressure, and fasting plasma glucose (FPG), serum lipids, uric acid, insulin, and leptin concentrations were measured. The TNF-alpha G-308A polymorphism was assessed by the polymerase chain reaction restriction fragment length polymorphism method. In the young group, 4 subjects (3.3%) were heterozygous for the TNF2 (G-308A-positive) allele, but there were no significant differences between the TNF1 (wild-type) and TNF2 groups in any measured anthropometric or metabolic parameter. In the older group, the frequency of the TNF2 group was 2.8%, and FPG was significantly higher in the TNF2 versus the TNF1 group (108 +/- 7 v 99 +/- 9 mg/dL, P= .042 by Mann-Whitney Utest). Plasma triglycerides and the insulin resistance index tended to be higher and high-density lipoprotein (HDL) cholesterol tended to be lower in the TNF2 group (P = .06, .20, and .07, respectively), although these differences were not statistically significant. In type 2 diabetic subjects, the frequency of the TNF2 group was also 2.8%, and there were no significant differences between the TNF1 and TNF2 groups in any parameter. HDL cholesterol tended to be lower (P = .10) in the TNF2 group, although it was not statistically significant. In conclusion, no major difference was associated with TNF1 and TNF2 polymorphisms in terms of obesity, blood pressure, lipids, or glucose in young, older, or diabetic Japanese men, although FPG was significantly higher in older men, possibly through increased insulin resistance.

Grey-scale contrast enhancement in rabbit liver with DMP115 at different acoustic power levels

The contrast enhancement effect of ultrasound (US) contrast agent DMP-115 (YM454, Definity) in rabbit liver at two acoustic transmit power levels was studied. A total of 12 rabbits with healthy livers and 7 rabbits with VX-2 tumors were used. Grey-scale ultrasonograms in both fundamental (3.75 MHz) and harmonic (2.5/5.0 MHz) imaging modes were performed at a frame rate of 26 Hz under baseline acoustic power (MI = 0.6) or lower acoustic power (MI = 0.2). The contrast enhancement depended on the contrast agent dose and the acoustic power. The video intensity change was higher in the portal vein under the baseline acoustic power and higher in the liver parenchyma under the lower acoustic power. The contrast-enhanced US observation of the VX-2 tumor in the arterial phase correlated well with the angiographic and histopathological appearance of the tumor. In the parenchymal phase, the borderline of the tumor could be clearly delineated from the surrounding liver parenchyma. Continuous fundamental and harmonic grey-scale imaging with DMP115 has the capability of making peripheral circulation images of liver parenchyma and tumors.

EUS changes predictive for recurrence of esophageal varices in patients treated by combined endoscopic ligation and sclerotherapy

BACKGROUND

Recurrence of varices is still common after endoscopic treatment of esophageal varices. In this study, predictive signs of variceal recurrence were investigated by ultrasonic (US) miniature probe in patients treated by combined endoscopic ligation and sclerotherapy.

METHODS

Detectability of vessels by US miniature probe was evaluated first in rats. In 41 patients treated by combined therapy, the esophagus and the cardia region were examined by US miniature probe. In 25 patients examined by percutaneous transhepatic portography, the relationship between US miniature probe and percutaneous transhepatic portography findings was evaluated.

RESULTS

The smallest vessel detected by US miniature probe was 0.3 mm in diameter in the study using intra-abdominal vessels of rat. After variceal eradication, US miniature probe showed intramural vessels in the cardia that were classified as follows: grade I, a few vessels (19 patients, 46%); grade II, uniformly scattered vessels (11, 27%); grade III, abundant vessels resembling a honeycomb (11, 27%). As the sonographic grade increased, the rate of variceal recurrence increased. As the venographic grade of staining in the distal esophagus increased, the esophageal wall became thicker and the sonographic grade at the cardia increased.

CONCLUSIONS

Endosonographic evaluation of the distal esophagus and cardia is predictive of variceal recurrence.

Affinity selection of cDNA libraries by lambda phage surface display

Bacteriophage lambda surface display was used to isolate cDNA clones encoding autoantigens recognized by sera from patients with Sjögren's syndrome (SS). We made cDNA libraries from human HeLa and HepG2 cells, using the expression vector lambdafoo. By repeating affinity selection of the libraries with the sera immobilized in microtiter wells, we isolated three clones that encode previously unknown antigens as well as four clones previously known as SS autoantigens. The newly identified autoantigens include TRK-fused gene product (TFG), survival motor neuron gene product (SMN) and pM5, which has a similarity to the metal-binding domain of human fibroblast collagenase. Thus, the bacteriophage lambda surface display is powerful for isolating cDNA clones by affinity screening.

Molecular and clinical analysis of Japanese patients with 3-hydroxy-3-methylglutaryl CoA lyase (HL) deficiency

Deficiency of mitochondrial 3-hydroxy-3-methylglutaryl CoA lyase (HL, EC4.1.3.4.) is an autosomal recessive genetic disorder characterized by acute episodes of vomiting, hypotonia, and lethargy in the neonatal period or in infancy. Except in Saudi Arabia, where HL deficiency is the most common organic acidemia, the disorder is quite rare with only 41 cases being reported in the English literature, and only five known cases among Japanese. In this study, we present the results of a molecular analysis of all five Japanese patients together with their clinical phenotypes. Five different mutations in the HL gene were identified: one large deletion, one nonsense mutation, one missense mutation, and two splice mutations. Except for G835A (E279K) with its relatively common occurrence among Japanese, these mutations were unique to each family. The results of expression studies with mutated HL cDNAs confirmed the pathogenicity of these mutations and supported the importance of previously identified functional domains of the HL molecule, i.e., the putative catalytic site or dimerization site. In addition, we identified an alternative splicing event that resulted in the skipping of exons 5 and 6. This alternatively spliced product did not show HL activity and was present in various tissues of normal subjects. Clinically, all patients presented with similar symptoms, except that the timing of the initial presentation varied considerably, from 1 day to 1 year 3 months. In general, patients with null-activity mutations presented earlier in life, whereas those with residual activities presented later.

Expression of multiple UNC-13 proteins in the Caenorhabditis elegans nervous system

The Caenorhabditis elegans UNC-13 protein and its mammalian homologues are important for normal neurotransmitter release. We have identified a set of transcripts from the unc-13 locus in C. elegans resulting from alternative splicing and apparent alternative promoters. These transcripts encode proteins that are identical in their C-terminal regions but that vary in their N-terminal regions. The most abundant protein form is localized to most or all synapses. We have analyzed the sequence alterations, immunostaining patterns, and behavioral phenotypes of 31 independent unc-13 alleles. Many of these mutations are transcript-specific; their phenotypes suggest that the different UNC-13 forms have different cellular functions. We have also isolated a deletion allele that is predicted to disrupt all UNC-13 protein products; animals homozygous for this null allele are able to complete embryogenesis and hatch, but they die as paralyzed first-stage larvae. Transgenic expression of the entire gene rescues the behavior of mutants fully; transgenic overexpression of one of the transcripts can partially compensate for the genetic loss of another. This finding suggests some degree of functional overlap of the different protein products.

Characterization and chromosomal mapping of a novel human gene, ANKHZN

Ankhzn (ankyrin repeats hooked to a zinc finger motif) was originally isolated by means of the gene trap method, as a novel cytoplasmic protein on mouse embryonic stem cells. The Ankhzn protein is ubiquitously expressed in a spatiotemporal-specific manner and is located on endosomes. In the present study, we have cloned human ANKHZN cDNA by PCR using candidate EST clones exhibiting a high homology to mouse Ankhzn cDNA. The human ANKHZN cDNA encoded a 1166aa protein exhibiting 84.9% identity to the mouse one. The size of the transcript was found to be about 7kb on a Northern blot analysis, and ANKHZN mRNA was found to be ubiquitously expressed in human tissues on RT-PCR analysis. Western blot analysis showed that a 130kDa protein was detected at various levels in human tissues and also present in both membrane and soluble fractions obtained on subcellular fractionation. Human ANKHZN is a single copy gene consisting of predicted 25 exons in the human genome, and has been mapped to human chromosome 17p13 by radiation hybrid panel and fluorescence in-situ hybridization.

The steady-state kinetics of the enzyme reaction tested by site-directed mutagenesis of hydrophobic residues (Val, Leu, and Cys) in the C-terminal alpha-helix of human adenylate kinase

To elucidate whether the C-terminal region in human adenylate kinase participates in the interaction with the substrate (MgATP(2-) and/or AMP(2-)), hydrophobic residues (Val182, Val186, Cys187, Leu190, and Leu193) were substituted by site-directed mutagenesis and the steady-state kinetics of fifteen mutants were analyzed. A change in the hydrophobic residues in the C-terminal domain affects the affinity for substrates (K(m)), that is, not only for MgATP(2-) but also for AMP(2-), and the catalytic efficiency (k(cat)). The results obtained have led to the following conclusions: (i) Val182 may interact with both MgATP(2-) and AMP(2-) substrates, but to a greater extent with MgATP(2-), and play a role in catalysis. (ii) Val186 appears to play a functional role in catalysis by interacting with both MgATP(2-) and AMP(2-) to nearly the same extent. (iii) Cys187 appears to play a functional role in catalysis. (iv) Leu190 appears to interact with both MgATP(2-) and AMP(2-) substrates but to a greater extent with AMP(2-). (v) Leu193 appears to interact with both MgATP(2-) and AMP(2-) but to a greater extent with AMP(2-). The activity of all mutants decreased due to the change in substrate-affinity. The closer the residue is located to the C-terminal end, the more its mutation affects not only MgATP(2-) but also AMP(2-) substrate binding. The hydrophobic alterations disrupt hydrophobic interactions with substrates and that might destabilize the conformation of the active site. The more C-terminal part of the alpha-helix appears to interact with AMP, as if it has swung out and rotated to cover the adenine moieties. The C-terminal alpha-helix of human adenylate kinase appears to be essential for the interaction with adenine substrates by swinging out during catalysis.

Schistosoma mansoni infection cancels the susceptibility to Plasmodium chabaudi through induction of type 1 immune responses in A/J mice

Susceptibility to Plasmodium chabaudi depends on the relative dominance of T(h)1/T(h)2 responses in host mice. A T(h)2-dominant response during the early phase of infection in susceptible A/J mice causes a fatal disease course due to severe malaria. Schistosoma mansoni is a potent inducer of a T(h)2-dominant response not only to the parasite antigens, but also to other antigens concurrently existing in the host animals. In spite of S. mansoni infection, these A/J mice escape death from malaria and showed accompanied enhanced production of IFN-gamma to malaria antigens. Treatment with anti-IFN-gamma mAb in S. mansoni-infected A/J mice abolished the resistance to malaria, indicating that IFN-gamma was responsible for the resistance to P. chabaudi in S. mansoni-infected A/J mice. Results in this study show that under certain circumstances, S. mansoni infection can promote type 1 immune responses in A/J mice that normally develop T(h)2 responses.

Strongyloides venezuelensis: heparin-binding adhesion substances in immunologically damaged adult worms

Immunologically damaged Strongyloides venezuelensis adult worms were examined for their mucosal invasion ability and secretion of heparin-binding adhesion substances. S. venezuelensis was expelled from male Wistar rats 4 to 5 weeks after infection. Four-week-old adult worms were smaller and had fewer eggs than 1-week-old adult worms. One-week-old, 4-week-old, and 5-week-old adult worms equally established in the recipient mouse intestine when surgically implanted. Adult worms of 4 and 5 weeks of age secreted adhesion substances as much as 1-week-old adult worms. There was no difference in the heparin-binding activities and the lectin-binding profile of adhesion substances among adult worms of different ages. The rate of secretion of adhesion substances from the mouth was also identical. Heparin-binding activities were detected in crude adult worm proteins; however, proteins of 5-week-old adult worms had weaker heparin-binding activities than those of 1-week-old adult worms. Western blotting revealed that a number of heparin-binding proteins were lost in 5-week-old adult worms. A heparin-binding protein of 42. 0 kDa, which was consistently expressed in adult worms, was a possible component of heparin-binding adhesion substances which are secreted from the mouth.

Successful removal of an infected pacemaker electrode by open heart surgery under extracorporeal circulation

A 33-year-old male with sick sinus syndrome, who had received a pacemaker implant 18 years earlier, was complicated with a generator infection. Although the infected generator was removed, he was suffered from the recurrent local infection associated with a retained pacemaker lead. After a new pacemaker system implantation from the other side of the subclavian vein, we attempted to remove the lead utilizing a pacemaker removal kit. However, this intervention procedure was unsuccessful, because fibrous adhesions had developed around the lead, accompanied by calcification along its course. As a last resort, we opened the heart under extracorporeal circulation and removed the lead under direct vision. The post-operative course was uneventful. In order to remove a long-term implanted pacemaker lead, the direct surgical procedure with extracorporeal circulation is a favorable mean alternative to conventional intervention techniques.

Protective mechanisms against the intestinal nematode Strongyloides venezuelensis in Schistosoma japonicum-infected mice

Mice infected with Schistosoma japonicum were resistant to the intestinal nematode, Strongyloides venezuelensis. The numbers of adult S. venezuelensis recovered from mice were significantly decreased when infections were given from 6 weeks after S. japonicum infection. Larval recovery from the lungs showed that significant numbers of subcutaneously inoculated S. venezuelensis larvae were eliminated by 3 days in S. japonicum-infected mice (P < 0.0001), while histology revealed that this was associated with massive eosinophilic infiltration in the lungs. In addition, adult S. venezuelensis worms implanted in the duodenum of S. japonicum-infected mice could not establish in the intestine. This failure was associated with mucosal mastocytosis. Activation of eosinophils and intestinal mast cells was correlated with elevated expression of mRNA for interleukin (IL)-3, IL-4, and IL-5 in S. japonicum-infected mice. Sera from S. japonicum-infected mice recognized S. venezuelensis larva antigens as strongly as those from S. venezuelensis-infected mice, although transfer of sera from S. japonicum-infected mice to normal recipient mice did not protect them from S. venezuelensis challenge infection. It was concluded that the mechanisms for larval killing and adult worm expulsion of S. venezuelensis in S. japonicum-infected mice were identical to those seen in infections with S. venezuelensis only.

Thoracic aortic dissection in a patient with autosomal dominant polycystic kidney disease treated with maintenance hemodialysis

A patient with autosomal dominant polycystic kidney disease (ADPKD) on maintenance hemodialysis (HD) experienced spreading back pain with a sudden onset, and was diagnosed with thoracic aortic dissection. Reports of ADPKD with aortic dissection are rare. Hypertension, which is essentially universal both among ADPKD and hemodialysis patients, is a known risk factor for aortic dissection. Additionally, some reports have indicated that patients with ADPKD have aortic fragility. We suspect that aortic dissection may be less rare than presently apparent among HD patients with ADPKD.

A role of mast cell glycosaminoglycans for the immunological expulsion of intestinal nematode, Strongyloides venezuelensis

We examined effects of mast cell glycosaminoglycans on the establishment of the intestinal nematode, Strongyloides venezuelensis, in the mouse small intestine. When intestinal mastocytosis occurred, surgically implanted adult worms could not invade and establish in the intestinal mucosa. In mast cell-deficient W/Wv mice, inhibition of adult worm invasion was not evident as compared with littermate +/+ control mice. Mucosal mastocytosis and inhibition of S. venezuelensis adult worm mucosal invasion was tightly correlated. To determine effector molecules for the invasion inhibition, adult worms were implanted with various sulfated carbohydrates including mast cell glycosaminoglycans. Among sulfated carbohydrates tested, chondroitin sulfate (ChS)-A, ChS-E, heparin, and dextran sulfate inhibited invasion of adult worms into intestinal mucosa in vivo. No significant inhibition was observed with ChS-C, desulfated chondroitin, and dextran. ChS-E, heparin, and dextran sulfate inhibited adhesion of S. venezuelensis adult worms to plastic surfaces in vitro. Furthermore, binding of intestinal epithelial cells to adhesion substances of S. venezuelensis, which have been implicated in mucosal invasion, was inhibited by ChS-E, heparin, and dextran sulfate. Because adult worms of S. venezuelensis were actively moving in the intestinal mucosa, probably exiting and reentering during infection, the possible expulsion mechanism for S. venezuelensis is inhibition by mast cell glycosaminoglycans of attachment and subsequent invasion of adult worms into intestinal epithelium.

Adsorption of Water-Soluble Proteins onto Bubbles in Continuous Foam Separation

The mechanism of water-soluble protein enrichment in continuous foam separation was studied. The liquid flow rate and the protein concentration in the foam phase were measured at various heights from the interface between the bulk liquid and foam layer, and the intrinsic values at the interface were estimated by the extrapolation method to determine the accurate adsorption density on the bubble surface. Ovalbumin (OA) and hemoglobin (HB) were used as the soluble proteins. The solution pH values were varied from 3.5 to 6.0 for OA and from 6.0 to 8.0 for HB. The experimental isotherms for OA and HB were compared to the Langmuir isotherm, and the two adsorption parameters of the equilibrium constant, K, and the saturated density, gamma, at each pH were determined. Both gamma values obtained for OA and HB showed maxima at their isoelectric point (pH 4.6 for OA and pH 6.8 for HB). Assuming that OA and HB molecules are spherical in shape and are adsorbed on the bubble surface in a close-packed structure at saturation, the calculated diameters for OA and HB molecules were quite similar to the literature values. The variation in gamma for both OA and HB is discussed qualitatively in relation to the net charge of the protein molecule. Copyright 2000 Academic Press.

[A case of alcoholic multiple nervous system degeneration]

Chronic ethyl alcohol abuse is associated with different types of neurological involvement. We report a 51-year-old woman with alcoholic encephalopathy, neuropathy and autonomic dysfunction. After the alcohol abuse of about thirty years, gait disturbance, dysphagia and dysarthria progressively worsened. We thought that the disease was caused by poor nutrition due to chronic alcohol abuse and vitamin B1, B12 deficiency. Her neurological symptoms and signs improved after discontinuation of alcohol and nutritional treatment.

Coexpression of FAS and FAS-ligand in chronic pancreatitis: correlation with apoptosis

Activation of the Fas receptor by Fas-ligand (FasL) results in apoptosis, and dysregulation of this pathway may contribute to abnormal cell proliferation and cell death. The aim of this study was to compare the expression of Fas and FasL in the normal pancreas and chronic pancreatitis (CP). By Northern blotting, Fas messenger RNA (mRNA) levels were increased in CP in comparison to the normal pancreas. Immunostaining revealed that faint Fas and FasL immunoreactivity was present in ductal and islet cells of the normal pancreas. In CP, there was faint Fas and strong FasL immunoreactivity in the proliferating ductal cells. Additionally, many of these ductal cells in the CP samples exhibited an apoptotic signal, as determined by DNA 3'-OH end labeling. These findings suggest that activation of apoptosis through the Fas receptor may contribute to the pathobiology of CP.

Enhanced color flow images in small hepatocellular carcinoma

BACKGROUND

Features of enhanced color flow images in small hepatocellular carcinoma (HCC) are not fully elucidated. The purpose of this study was to clarify the characteristic vascular images in small HCC observed by enhanced color Doppler.

METHODS

Enhanced color Doppler using the contrast agent Levovist was performed on 13 patients with HCC smaller than 30 mm. Enhanced color flow appearance was compared with angiographic findings. Time-intensity changes after injection of the contrast agent were analyzed in HCC nodules.

RESULTS

Significant improvement in the detection of color flow signals was obtained in small HCC using Levovist, from 33% in precontrast to 92% in postcontrast (p < 0.005). Three patterns of enhanced color flow images, which were related to the angiographic findings, were observed. The time-intensity curve was classified into two types by "time to peak" and "time on plateau" and was associated with the patterns of enhanced images.

CONCLUSION

Enhanced color flow imaging promises to be a useful method for evaluating tumor vascularity noninvasively and to contribute to the elucidation of the hemodynamics in small HCC.

Continuous erythropoietin delivery by muscle-targeted gene transfer using in vivo electroporation

It has been demonstrated that gene transfer by in vivo electroporation of mouse muscle increases the level of gene expression by more than 100-fold over simple plasmid DNA injection. We tested continuous rat erythropoietin (Epo) delivery by this method in normal rats, using plasmid DNA expressing rat Epo (pCAGGS-Epo) as the vector. A pair of electrodes was inserted into the thigh muscles of rat hind limbs and 100 microg of pCAGGS-Epo was injected between the electrodes. Eight 100-V, 50-msec electric pulses were delivered through the electrodes. Each rat was injected with a total of 400 microg of pCAGGS-Epo, which was delivered to the medial and lateral sides of each thigh. The presence of vector-derived Epo mRNA at the DNA injection site was confirmed by RT-PCR. The serum Epo levels peaked at 122.2 +/- 33.0 mU/ml on day 7 and gradually decreased to 35.9 +/- 18.2 mU/ml on day 32. The hematocrit levels increased continuously, from the preinjection level of 49.5 +/- 1.1 to 67.8 +/- 2.2% on day 32 (p < 0.001). In pCAGGS-Epo treated rats, endogenous Epo secretion was downregulated on day 32. In a control experiment, intramuscular injection of pCAGGS-Epo without subsequent electroporation did not significantly enhance the serum Epo levels. These results demonstrate that muscle-targeted pCAGGS-Epo transfer by in vivo electroporation is a useful procedure for the continuous delivery of Epo.

Lack of an association of estrogen receptor alpha gene polymorphisms and transcriptional activity with Alzheimer disease

BACKGROUND

Long-term cognitive decline in postmenopausal women is associated with aging and Alzheimer disease (AD). Estrogen replacement therapy has been reported to reduce the risk of developing AD. The distribution of estrogen receptors (ERs) in neurons overlaps that of the brain neurons known to develop AD. Estrogen increases the secretion and metabolism of amyloid precursor protein, may help synapse formation, and is reported to protect neurons from toxins. Restriction fragment length polymorphisms (RFLPs) of the ERalpha gene at intron 1 and exon 2 were associated with a low bone mineral density in postmenopausal women and also with AD in a Japanese population.

OBJECTIVE

To determine whether ERalpha gene polymorphisms are associated with transcriptional activity and AD.

METHODS

A luciferase reporter assay analyzed enhancer activity of the ERalpha gene at intron 1 and exon 2. This activity was evaluated according to the RFLPs. The RFLPs of the ERalpha gene were determined in Japanese patients clinically diagnosed as having AD, white patients diagnosed as having AD at autopsy, and corresponding healthy control subjects. The RFLPs were also evaluated for the contribution of the ERalpha gene RFLPs to AD.

RESULTS

We found weak (about 2-fold) enhancer activity of the ERalpha gene, which differed among RFLPs. Although there were racial differences in these polymorphisms, we could not confirm the previously reported association between ERalpha gene polymorphisms and AD.

CONCLUSION

Regulatory element of the ERalpha gene was found in intron 1, but we found no association between ERalpha gene polymorphisms and AD.

Suppression of lethal toxicity of endotoxin by biscoclaurine alkaloid cepharanthin

Suppressive effects of Cepharanthin (CE) on lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNFalpha) production followed by liver injury were investigated. Pretreatment with CE reduced limulus activity of LPS. Intraperitoneal treatment with CE 10 min before an i.v. challenge of LPS resulted in protection from LPS lethality in D-galactosamine (GalN)-sensitized BALB/c but not in C57BL/6 and C57BL/10ScSn mice. Treatment with CE before the LPS challenge significantly reduced serum TNF levels in a dose-dependent manner. The suppression was most effective when CE was administered 10 min before the LPS challenge. Increased levels of enzymes released from hepatocytes into the circulation, as a result of LPS-induced liver injury, were reduced by CE administration. Histological evaluation demonstrated that massive cell infiltration after severe injury developed in liver of mice injected with LPS plus D-GalN unless they were pretreated with CE. Apoptotic cells decreased by treatment with CE. Treatment with CE retarded lethal shock induced by an infection with 10(8) CFU Salmonella typhimurium deltaaroA mutant. These results suggest that action of CE is initiated through suppression of LPS-induced TNF production.

Cloning and molecular characterization of calpain, a calcium-activated neutral proteinase, from different strains of Schistosoma japonicum

cDNA coding for calpain of Schistosoma japonicum were cloned and sequenced, and serological basis of host responses to calpain were analyzed. cDNA of calpain from S. japonicum of two different isolates, Yamanashi strain (Sj-J) and Hunan strain (Sj-C), were 2, 468 bp and 2, 465 bp in length, including the same number (2, 274) of open reading frame. Nucleotide sequence and amino acid sequence between the two calpains are 99.1% and 98.8% identity, respectively. Sj-J and Sj-C calpains were considered to be translated as a preproenzyme, and a 746-amino acid mature enzyme contains eight motifs without a signal peptide at the N-terminal based on the deduced amino acid sequences. mRNA for calpain were detectable in different developmental stages, however, sera obtained from mice immunized with recombinant calpain showed enhanced binding to cercarial antigen. Human sera from S. japonicum-infected individuals recognized the large subunit of schistosomal calpain, and light-infected sera showed stronger reactivities to the recombinant calpain than moderate/high infection cases. When we tested synthetic peptides, there were four common human B cell epitopes in schistosomal calpain, all of which are shared with S. mansoni. Together with these results, calpain of S. japonicum seems to be not only a vaccine candidate, but also a target antigen for immunodiagnosis of human schistosomiasis.

A possible barrier function of the articular surface

Since MacConaill first reported the existence of a thin additional layer of the articular cartilage and named it the lamina splendens, there have been various opinions as to the role of this layer in the lubrication of the articular surface. We studied the superficial portion of the articular cartilage in the 20 day-old and 30 day-old rats using light and transmission electron microscopy. Furthermore, we studied the articular cartilage of the rat whose "cover layer" had been removed mechanically. Also, intraarticular latex beads injection, intraarticular dye injection using lithium carmine and supravital staining experiments were performed. On day 20, dye injected intraarticularly was clearly observed by light microscopy in chondrocytes situated in the deeper layers. The dye injected in the 30 day-old rats, however, was not seen in the chondrocytes but was found only in the superficial layer. Dye was found in the chondrocytes when supravital staining was performed in the articular cartilage of 30 day-old rats after mechanical removal of the cover layer. By transmission electron microscopy, a superficial layer consisted of fine filamentous structures was observed on the articular surface of the 30 day-old rats. The cover layer was destroyed by intraarticular injected latex beads in 30 day-old rats. These findings strongly support the idea that the cover layer acts as a barrier against substances which invade from the surface of the articular cartilage. The development period of the cover layer coincides with the initiation of weight bearing, and joint cartilage debris and pressure changes might further promote maturation.