Effects of methylation of arginine residue 83 on the enzymatic activity of human arsenic (+3 oxidation state) methyltransferase

Arsenic (+3 oxidation state) methyltransferase is an enzyme responsible for arsenic methylation, and it requires S-adenosyl-methionine (SAM) as a coenzyme. We here generated two mutants to clarify the role of the highly conserved 83rd arginine residue (Arg83) in Motif I, the SAM-binding domain, of human AS3MT. When the AS3MT activity was compared between the mutants and the wild type (WT) recombinant protein, little activity was detected in the glycine mutant (Arg83Gly) or lysine mutant (Arg83Lys). When we examined the ability of transfected HEK293 cells exposed to arsenite to methylate arsenic, the methylation ability was significantly reduced in Arg83Gly compared to the WT, but was not significantly different between Arg83Lys and WT. Western blot analysis of the recombinant WT and Arg83Gly with an antibody that recognizes methylated Arg showed that an Arg residue in the WT was mono- and di-methylated, but not in Arg83Gly. Furthermore, a peptide containing dimethylated Arg83 was detected by MALDI-TOF/MS of the WT digested with chymotrypsin. These results indicate that AS3MT maintains its enzymatic activity through the methyl modification of Arg83.

Anatomical study of the bone morphology of the anterior talofibular ligament attachment

Anterior talofibular ligament (ATFL) injuries are the most common cause of ankle sprains. To ensure anatomically accurate surgery and ultrasound imaging of the ATFL, anatomical knowledge of the bony landmarks around the ATFL attachment to the distal fibula is required. The purpose of the present study was to anatomically investigate the ATFL attachment to the fibula with respect to bone morphology and attachment structures. First, we analyzed 36 feet using microcomputed tomography. After excluding 9 feet for deformities, the remaining 27 feet were used for chemically debrided bone analysis and macroscopic and histological observations. Ten feet of living specimens were observed using ultrasonography. We found that a bony ridge was present at the boundary between the attachments of the ATFL and calcaneofibular ligament (CFL) to the fibula. These two attachments could be distinguished based on a difference in fiber orientation. Histologically, the ATFL was attached to the anterodistal part of the fibula via fibrocartilage anterior to the bony ridge indicating the border with the CFL attachment. Using ultrasonography in living specimens, the bony ridge and hyperechoic fibrillar pattern of the ATFL could be visualized. We established that the bony ridge corresponded to the posterior margin of the ATFL attachment itself. The ridge was obvious, and the superior fibers of the ATFL have directly attached anteriorly to it. This bony ridge could become a valuable and easy-to-use landmark for ultrasound imaging of the ATFL attachment if combined with the identification of the fibrillar pattern of the ATFL.

CHAC1 exacerbates arsenite cytotoxicity by lowering intracellular glutathione levels

We here examined whether CHAC1 is implicated in arsenite (As(III))-induced cytotoxicity in HaCaT cells. We found that HaCaT cells in which the intracellular GSH levels were elevated by transfection with CHAC1 siRNA showed decreased sensitivity to As(III) compared to the control cells. Treatment with BSO (an inhibitor of GSH biosynthesis) abolished the decrease in sensitivity to As(III), suggesting that an increase in intracellular GSH levels was involved in the decrease in sensitivity to As(III) due to the decrease in the levels of CHAC1 expression. When we examined the expression of CHAC1 after exposure of HaCaT cells to As(III), the levels of CHAC1 were increased. Since CHAC1 is a proapoptotic factor, we examined appearance of apoptotic cells and cleavage of caspase-3 after exposure to As(III) to determine whether As(III)-induced CHAC1 up-regulation was involved in apoptosis induction. The results showed that induction of apoptosis by As(III) exposure was not detected in CHAC1 siRNA-transfected cells. Together, our findings indicate that CHAC1 is involved in the sensitivity of HaCaT cells to As(III) by regulating the intracellular GSH levels, and in particular, CHAC1 is involved in As(III)-induced apoptosis.

Lateral Ulnar Collateral Ligament of the Elbow Joint: Reconsideration of Anatomy in Terms of Connection with Surrounding Fibrous Structures

BACKGROUND

To improve the clinical results of lateral ulnar collateral ligament (LUCL) reconstruction of the elbow joint, better understanding of the anatomy of the aponeuroses and joint capsule could be relevant. This study considers the previously described anatomy of the LUCL in relation to the related aponeuroses and joint capsule rather than as a discrete ligament. We hypothesized that the deep aponeuroses of the superficial extensor muscles and supinator form a relevant portion of the joint capsule previously defined as the LUCL.

METHODS

Twenty-four elbows (12 right) from 21 embalmed cadavers (age at the time of death, 54 to 99 years) were included in the study. Twenty elbows were studied macroscopically and 4, histologically. The joint capsule was detached from the bones, and local thickness was quantitatively analyzed using micro-computed tomography (micro-CT).

RESULTS

The supinator aponeurosis and joint capsule intermingled to form a thick membrane (mean and standard deviation, 4.8 ± 1.2 mm), which we termed "the capsulo-aponeurotic membrane." It was thicker than the anterior (1.3 ± 0.4 mm) and posterior (2.5 ± 0.9 mm) parts of the capsule of the humeroradial joint (p < 0.001). The capsulo-aponeurotic membrane had a wide attachment on the distal part of the extensor digitorum communis and extensor digiti minimi (EDC/EDM) origin of the humerus, the lateral part of the coronoid process, and the posterior part of the radial notch of the ulna. The humeral attachment had a fibrocartilaginous structure. The deep aponeuroses of the EDC and extensor carpi ulnaris (ECU) were connected to the capsulo-aponeurotic membrane.

CONCLUSIONS

The capsulo-aponeurotic membrane was composed of the supinator aponeurosis and joint capsule and was attached to the lateral epicondyle of the humerus, radial side of the coronoid process, and posterior part of the radial notch on the ulna. The entire structure appeared identical to the commonly defined lateral collateral ligament. The most posterior part was connected to the EDC and ECU aponeuroses, which is commonly labeled the LUCL but does not exist as a discrete ligament.

CLINICAL RELEVANCE

Consideration of the accurate anatomy of the extensive attachment of the capsulo-aponeurotic membrane could provide useful clues for improvement in techniques of LUCL reconstruction and lateral epicondylitis pathology.

Manganese transport in mammals by zinc transporter family proteins, ZNT and ZIP

Manganese (Mn) is an essential trace element required for various biological processes. However, excess Mn causes serious side effects in humans, including parkinsonism. Thus, elucidation of Mn homeostasis at the systemic, cellular, and molecular levels is important. Many metal transporters and channels can be involved in the transport and homeostasis of Mn, and an increasing body of evidence shows that several zinc (Zn) transporters belonging to the ZIP and ZNT families, specifically, ZNT10, ZIP8, and ZIP14, play pivotal roles in Mn metabolism. Mutations in the genes encoding these transporter proteins are associated with congenital disorders related to dysregulated Mn homeostasis in humans. Moreover, single nucleotide polymorphisms of ZIP8 are associated with multiple clinical phenotypes. In this review, we discuss the recent literature on the structural and biochemical features of ZNT10, ZIP8, and ZIP14, including transport mechanisms, regulation of expression, and pathophysiological functions. Because a disturbance in Mn homeostasis is closely associated with a variety of phenotypes and risk of human diseases, these transporters constitute a significant target for drug development. An understanding of the roles of these key transporters in Mn metabolism should provide new insights into pharmacological applications of their inhibitors and enhancers in human diseases.

[Roles of Zinc Transporters That Control the Essentiality and Toxicity of Manganese and Cadmium]

Cellular transport systems for both essential and toxic trace elements remain elusive. In our studies on the transport systems for cadmium (Cd), we found that the cellular uptake of Cd is mediated by the transporter for manganese (Mn). We identified ZIP8 and ZIP14, members of the ZIP zinc (Zn) transporter family, as transporters having high affinities for both Cd and Mn. Notably, the uptake of Cd into rice root from soil is mediated by a transporter for Mn as well. We found that ZIP8 is highly expressed at the S3 segment of the kidney proximal tubule and can transport glomerulus-filtered Cd and Mn ions in the lumen into epithelial cells of the proximal tubule, suggesting that ZIP8 has an important role in the renal reabsorption of both toxic Cd and essential Mn. Mutations in ZIP8 and ZIP14 genes were found in humans having congenital disorders associated with the disturbed transport of Mn, although ZIP8 mutation causes whole-body Mn deficiency while ZIP14 mutation causes Mn accumulation in the brain. Mutations in ZnT10, a Zn transporter responsible for Mn excretion, also cause hyperaccumulation of Mn in the brain. Results of genome-wide association studies have indicated that ZIP8 SNPs are involved in a variety of common diseases. Thus, ZIP8, ZIP14, and ZnT10 play crucial roles in the transport of Mn and thereby control Mn- and Cd-related biological events in the body.

Comparisons of segment-specific toxicity of platinum-based agents and cadmium using S1, S2, and S3 cells derived from mouse kidney proximal tubules

Renal toxicants such as cisplatin and cadmium cause segment-specific damages in kidney proximal tubules. Recently, we established an in vitro experimental system for evaluating segment-specific toxicity and transport of chemicals using immortalized S1, S2, and S3 cells derived from the S1, S2, and S3 regions of mouse kidney proximal tubules. In the present study, we examined the toxicity and accumulation of cisplatin, carboplatin, oxaliplatin, and cadmium in S1, S2, and S3 cells. We found that not only cisplatin but also carboplatin and oxaliplatin exhibited higher lethal toxicity in S3 cells than in S1 and S2 cells. At sublethal doses, cisplatin showed delayed induction of Kim-1 and clusterin on days 3 and 6, which may reflect the latent renal toxicity of cisplatin in vivo. The high sensitivities of S3 cells to the platinum-based agents were not due to the high accumulation of Pt in S3 cells. Exposure to cadmium resulted in similar toxicity among these cells, suggesting that S3 cells were not sensitive to any renal toxicants. Thus, the utilization of S1, S2, and S3 cells may provide a useful tool for the in vitro evaluation of the proximal tubule segment-specific toxicity of chemicals.

Segment-specific and direction-dependent transport of cadmium and manganese in immortalized S1, S2, and S3 cells derived from mouse kidney proximal tubules

The kidney proximal tubule is a target of many renal toxicants, including cadmium (Cd), and also a place of reabsorption of essential metals in glomerular filtrate to systemic circulation. Although the mechanisms of metal transport in the convoluted proximal tubule (S1 and S2 segments) and the straight proximal tubule (S3 segment) may differ, little is known about the segment-specific modes of metal transport. Here, we utilized immortalized cell lines derived from the S1, S2, and S3 segments of mouse kidney proximal tubules, and examined the segment-specific and direction-dependent transport of Cd and manganese (Mn) using a trans-well culture system. The results showed that the uptakes of Cd²⁺ and Mn²⁺ from apical sides were the highest in S3 cells, and Cd²⁺, Mn²⁺, and Zn²⁺ mutually inhibited the apical uptake of each metal. As the expression of ZIP8, a zinc transporter having affinities for Cd²⁺ and Mn²⁺, was the highest in S3 cells, ZIP8 may contribute largely to the apical uptakes of these metals. The efficient uptake of Mn²⁺ from apical side of S3 cells may suggest an important role of ZIP8 in proximal tubule in reabsorption of Mn, an essential metal. Our study demonstrated that S1, S2, and S3 cells provide a useful tool for studying the segment-specific and direction-dependent transport of both toxic and essential metals in the kidney's proximal tubules.

New Insights into the Roles of ZIP8, a Cadmium and Manganese Transporter, and Its Relation to Human Diseases

ZIP8, a Zrt-/Irt-related protein encoded by Slc39A8, was originally discovered as a zinc transporter, but since then its roles as a transporter for cadmium (Cd) and manganese (Mn) have also been well characterized. ZIP8 is highly expressed in the S3 segment of the proximal tubules of the mouse kidney and may play a significant role in reabsorption of both toxic Cd and essential Mn from the lumen to the epithelial cells of the proximal tubule. In recent years, associations between various human diseases and genetic variations of ZIP8 have been reported. Missense mutations in the human SLC39A8 gene are associated with serious disorders of Mn metabolism, showing symptoms similar to congenital glycosylation deficiency. Enhanced excretion of Mn via bile or urine might be the cause of extremely low blood Mn levels in ZIP8-mutated patients, leading to the defects in Mn-dependent glycosylation. Several genome-wide association studies have demonstrated the associations of multiple diseases and ZIP8 SNPs constituting missense mutations. These findings suggest that ZIP8 plays more important roles than previously expected as a modulator of Mn homeostasis in the body. Elucidation of biochemical mechanisms regarding the metal-transporting ability of ZIP8 and its alteration by mutation is required for better understanding of the role of ZIP8 in human diseases.

Toxicometallomics of Cadmium, Manganese and Arsenic with Special Reference to the Roles of Metal Transporters

The transport systems for metals play crucial roles in both the physiological functions of essential metals and the toxic effects of hazardous metals in mammals and plants. In mammalian cells, Zn transporters such as ZIP8 and ZIP14 have been found to function as the transporters for Mn(II) and Cd(II), contributing to the maintenance of Mn homeostasis and metallothionein-independent transports of Cd, respectively. In rice, the Mn transporter OsNramp5 expressed in the root is used for the uptake of Cd from the soil. Japan began to cultivate OsNramp5 mutant rice, which was found to accumulate little Cd, to prevent Cd accumulation. Inorganic trivalent arsenic (As(III)) is absorbed into mammalian cells via aquaglyceroporin, a water and glycerol channel. The ortholog of aquaporin in rice, OsLsi1, was found to be an Si transporter expressed in rice root, and is responsible for the absorption of soil As(III) into the root. Since rice is a hyperaccumulator of Si, higher amounts of As(III) are incorporated into rice compared to other plants. Thus, the transporters of essential metals are also utilized to incorporate toxic metals in both mammals and plants, and understanding the mechanisms of metal transports is important for the development of mitigation strategies against food contamination.

Arsenite suppresses NO production evoked by lipopolysaccharide and poly(I:C) via the suppression of interferon-β expression in RAW264.7 cells

Immunological functions are disturbed in humans who have been chronically exposed to arsenic via contaminated groundwater. Little is known about the specific mechanisms underlying the impairment of immunological defense system caused by arsenic. The activation of macrophage cells upon infection with bacteria and viruses plays important roles in the defense against these pathogens. Here we show that exposure to arsenite (As(III)) suppresses nitric oxide (NO) production in murine RAW264.7 macrophage cells stimulated with lipopolysaccharide (LPS) and poly(I:C), the compounds mimicking bacterial and viral infection, respectively. As(III) suppressed the LPS- or poly(I:C)-evoked induction of inducible NO synthase (iNOS) without affecting the transactivation of NF-κB. As the interferon (IFN)-β/STAT1 pathway is also involved in the induction of iNOS in addition to NF-κB, we examined the effects of As(III) on the expression and secretion of IFN-β, the expression of the components of IFN-α/β receptor, the phosphorylation of STAT1, and the levels of cytokines involved in STAT1 activation. The results showed that the expression and secretion of IFN-β were specifically suppressed by As(III) treatment in RAW264.7 cells stimulated with LPS or poly(I:C). These results suggest that As(III) suppresses the expression and secretion of IFN-β, leading to the reduced STAT1 activation and consequently the reduced iNOS induction in macrophage cells. Our data suggest an important role of the arsenic-induced suppression of IFN-β on the disturbances in immunological defense against both bacteria and viruses.

Anatomic analysis of the whole articular capsule of the shoulder joint, with reference to the capsular attachment and thickness

Background

Although conventional Bankart repair has been the accepted procedure for traumatic anterior glenohumeral instability, the humeral avulsion of the glenohumeral ligament or an elongation of the capsule remains challenging to decide the appropriate treatment. The anatomical knowledge regarding the whole capsule of glenohumeral joint is necessary to accurately treat for the capsular disorders. The aims of the current study were to investigate the anatomical features of capsular attachment and thickness in a whole capsule of glenohumeral joint.

Methods

We used 13 shoulders in the current study. In 9 shoulders, we macroscopically measured the attachment widths of the capsulolabrum complex on the scapular glenoid, and the attachment widths of the capsule on the humerus in reference to the scapular origin of the long head of triceps brachii, and the humeral insertion of the rotator cuff tendons. We additionally used 4 cadaveric shoulders, which were embalmed using Thiel’s method, for the analysis of the thickness in a whole capsule by using micro-CT.

Results

The glenoidal attachment of the articular capsule appeared to have a consistent width except for the superior part of the origin of the long head of triceps brachii. On the humerus, the articular capsule was widely attached to areas without overlying rotator cuffs, with the widest width (17.3 ± 0.9 mm) attached to the axillary pouch. The inferior part of the capsule, which was consistently thicker than the superior part, continued to the superior part along the glenoid and humeral side edge.

Conclusions

The current study showed that the inferior part of the glenohumeral capsule had a wide humeral attachment from the inferior edge of the subscapularis insertion to the inferior edge of the teres minor insertion via the anatomical neck of the humerus, and the thickness of it was thicker than the superior part of the capsule.

Concentration-dependent roles of DMT1 and ZIP14 in cadmium absorption in Caco-2 cells

Intestinal absorption of cadmium (Cd) is considered to be mediated mainly by the ferrous iron transporter DMT1, or the calcium transporter CaT1. The roles of zinc transporters such as ZIP8 and ZIP14 remain unclear, and the roles of these four transporters in the intestinal uptake of Cd under physiological conditions have not been compared. Here, we used a trans-well cell culture system to investigate the effects of the down-regulation of these four transporters on the uptake of Cd from the apical side of enterocytes. We used a Caco-2-kh cell line that can form tight junctions within a few days. The transfection of DMT1 siRNA significantly decreased the Cd uptake from the apical side at 5 μM, but not at 0.1 or 1 μM. The transfection of ZIP14 siRNA markedly decreased the Cd uptake at 0.1 and 1 μM, but not at 5 μM. The transfection of siRNA of CaT1 or ZIP8 did not alter the Cd uptake at any concentrations of Cd examined. These results suggest that DMT1 and ZIP14 play different roles in intestinal Cd absorption depending on the concentration of Cd.

Protective effect of cadmium-induced autophagy in rat renal mesangial cells

Cadmium damages renal cells, and in particular may cause mesangial cell death by necrosis or apoptosis, depending on exposure conditions in cultured cells. However, there is an uncertainty as to whether Cd²⁺-induced autophagy can protect mesangial cells against these other mechanisms of cell death. We have used autophagy-incompetent mouse embryonic fibroblast (MEF) cells lacking the Atg16 gene, as well as cultured rat mesangial cells (RMC) in which Atg16 has been silenced, to examine this issue. Measuring the processing of LC3-I to LC3-II and expression of sequestosome-1 (p62), we define conditions under which RMC can be induced to undergo autophagy in response to 0-20 µM CdCl₂. Similarly, Cd²⁺ can initiate autophagy in MEF cells. However, when autophagy is compromised, either by gene knockout in MEF cells or by RNA silencing in RMC, cell viability is decreased, and concomitantly a Cd²⁺ dose-dependent increase in pro-caspase-3 cleavage indicates the initiation of apoptotic cell death. In contrast to some previous reports, Cd²⁺-induced autophagy is not correlated with increased levels of cellular reactive oxygen species but, among a panel of kinases investigated, is suppressed by inhibition of the Jun kinase. We conclude that concentrations of Cd²⁺ that initiate autophagy may afford renal mesangial cells some degree of protection against other modes (apoptosis, necrosis) of cell death.

Joint capsule attachment to the coronoid process of the ulna: an anatomic study with implications regarding the type 1 fractures of the coronoid process of the O'Driscoll classification

BACKGROUND

The attachment of the anterior joint capsule on the ulnar coronoid process is not yet completely understood. The purpose of this study was to clarify the anatomic relationship between the anterior capsule of the elbow joint and the tip of the coronoid process.

METHODS

Seventeen embalmed elbows were used for this anatomic study. The anterior capsule of the elbow joint was reflected, and the attachment of the capsule on the coronoid process was exposed. The attachment of the joint capsule on the coronoid process was macroscopically and histologically observed, its relationship to the coronoid tip was assessed, and the length of the attachment of the joint capsule was measured.

RESULTS

The length of the capsule attachment at the radial side of the coronoid (11.9 mm) was greater than that at the ulnar side (6.1 mm). The bone thickness on the coronoid tip from the proximal edge of the joint capsule attachment was 1.9 mm; together, the cartilage and bone thickness was 4.7 mm. At the radial side of the coronoid, the thickness of the joint capsule at the proximal aspect of the attachment of 2 samples was 0.6 mm and 0.3 mm, and that at the tip of the coronoid was 2.6 mm and 1.7 mm, respectively.

CONCLUSIONS

The anterior capsule of the elbow joint had a substantial attachment on the radial side of the coronoid process. The subtype 2 tip fractures of the O'Driscoll classification included the joint capsule attachment, joint cartilage, and subchondral bone.

Direct Comparison of Manganese Detoxification/Efflux Proteins and Molecular Characterization of ZnT10 Protein as a Manganese Transporter

Manganese homeostasis involves coordinated regulation of specific proteins involved in manganese influx and efflux. However, the proteins that are involved in detoxification/efflux have not been completely resolved nor has the basis by which they select their metal substrate. Here, we compared six proteins, which were reported to be involved in manganese detoxification/efflux, by evaluating their ability to reduce manganese toxicity in chicken DT40 cells, finding that human ZnT10 (hZnT10) was the most significant contributor. A domain swapping and substitution analysis between hZnT10 and the zinc-specific transporter hZnT1 showed that residue Asn(43), which corresponds to the His residue constituting the potential intramembranous zinc coordination site in other ZnT transporters, is necessary to impart hZnT10's unique manganese mobilization activity; residues Cys(52) and Leu(242) in transmembrane domains II and V play a subtler role in controlling the metal specificity of hZnT10. Interestingly, the His → Asn reversion mutant in hZnT1 conferred manganese transport activity and loss of zinc transport activity. These results provide important information about manganese detoxification/efflux mechanisms in vertebrate cells as well as the molecular characterization of hZnT10 as a manganese transporter.

An anatomic study of the attachments on the condylar process of the mandible: muscle bundles from the temporalis

PURPOSE

The aim of this study was to evaluate anatomically the relationship between bone and muscles by detailed observation of the bone shape and the structure of muscles to facilitate an understanding of the function of the muscles involved in jaw movement.

METHODS

36 specimens of 24 Japanese cadavers were examined. The insertion areas were marked using a radiopaque marker and examined by micro-computed tomography. For morphological observation, we used 101 condylar processes. In addition, we made histological sections in some specimens to observe the detailed attachments of the muscle.

RESULTS

Based on the micro-CT images and dissection findings, the lateral pterygoid muscle was found to be most frequently inserted into the anterior impression and attached to the medial impression of the process. According to the histological observations, the lateral pterygoid muscle mainly inserted to the condylar process. The micro-CT images indicated that the obvious bony ridge was lateral to the pterygoid fovea on the condylar process in all specimens. The midmedial muscle bundle of the temporalis was attached to the ridge. Based on the morphological observations, the ridge was situated on the lateral area of the condylar process.

CONCLUSIONS

Since dysfunction of the temporomandibular joint is likely closely related to both the lateral pterygoid muscle and also the temporalis, further studies are necessary to evaluate the function of these muscles and consider jaw movement.

The anatomic relationship between the morphology of the greater tubercle of the humerus and the insertion of the infraspinatus tendon

BACKGROUND

The objective of this study was to evaluate the topographic relationship between the morphology of the greater tubercle and the insertion of the tendon of the infraspinatus.

MATERIALS AND METHODS

First, we defined an impression of the greater tubercle, which has not been recognized in classic textbooks, as the "lateral impression" and then measured the dimensions of the "lateral impression" of the greater tubercle in 71 samples of dry bone of humeri. Next, we examined 16 cadaveric humeri with rotator cuff tendons by micro-computed tomography to analyze the positional relationship between the lateral impression and the infraspinatus tendon.

RESULTS

In all samples of dry bones, the lateral impression could be identified as a triangle shape. The lateral impression was composed of the border with the highest impression (mean, 6.3 mm), the border with the middle impression (mean, 5.0 mm), and the border with the lateral wall of the greater tubercle (mean, 8.5 mm). In all samples of humeri with rotator cuffs, we could confirm the lateral impression, and the border between the highest impression and the lateral impression corresponded to the anterior border of the insertion of the infraspinatus tendon.

CONCLUSION

We propose a new anatomic concept of the lateral impression that could enable the precise diagnosis of and facilitate repair techniques for infraspinatus tear, according to specific anatomic characteristics, by applying 3-dimensional computed tomography assessment preoperatively.

Anatomic variations of the lateral intercondylar ridge: relationship to the anterior margin of the anterior cruciate ligament

BACKGROUND

The lateral intercondylar ridge (LIR) has been recognized as an important landmark to create an appropriate femoral tunnel in single-bundle anterior cruciate ligament (ACL) reconstruction. However, because of variations in the distal part of the LIR or because the relationship between the LIR and the anterior margin of the ACL attachment has not been sufficiently clarified, the utility of the LIR for anatomic single- and double-bundle reconstruction remains controversial.

HYPOTHESES

(1) There is a large degree of positional and dimensional variation in the LIR, specifically concerning the distal part. (2) There may be significant differences between sexes in the LIR. (3) The anterior margin of the ACL attachment may be located anterior to the distal part of the LIR.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 318 femora, which were collected with the donors' demographic data, were examined to determine anatomic variations of the LIR. In addition, 20 cadaveric knees, in which the anterior margin was marked by radiopaque silicon markers, were examined with micro-computed tomography to evaluate the positional relationship between the LIR and the anterior margin of the ACL attachment.

RESULTS

Although the LIR was identified in 94.0% of the 318 femora, the distal half of the LIR was not visible in 18.4% of these femora. Moreover, the LIR was located in an extremely anterior part of the lateral condyle surface in 8.8% in comparison with the common location, and in an extremely posterior part in 8.5%. The length-height ratio (69.9% in men, 63.6% in women) and the length between the inlet of the notch roof and the proximal part of the LIR (19.9 mm in men, 17.9 mm in women) were significantly greater in males than in females (P = .0028 and P < .0001, respectively). The anterior margin of the ACL attachment was commonly located anterior to the middle and distal part of the LIR, having the mean marker-ridge distance of 4.2 mm.

CONCLUSION

There were large positional and dimensional variations in the LIR, specifically concerning the distal part. There are slight but significant differences between the male and female femora. The anterior margin of the ACL attachment is commonly located anterior to the middle and distal parts of the LIR.

CLINICAL RELEVANCE

Utility of the LIR as an osseous landmark for femoral tunnel creation is limited in anatomic reconstruction of the posterolateral bundle and anatomic single-bundle reconstruction.

Anatomic and histologic analysis of the mid-substance and fan-like extension fibres of the anterior cruciate ligament during knee motion, with special reference to the femoral attachment

PURPOSE

The purpose of this study is to evaluate the morphology of the mid-substance and fan-like extension fibres of ACL during knee motion with reference to the femoral attachment.

METHODS

This study used six fresh-frozen cadaveric knees and 22 embalmed cadaveric knees to macroscopically evaluate morphological changes in the ACL attachment during knee motion. Three embalmed specimens fixed at knee extension and another three specimens fixed at 120° flexion were used for histologic observations.

RESULTS

The fan-like extension fibres were adhered to the bone surface and the fibre location and orientation in relation to the femoral surface did not change, regardless of the knee flexion angle, while the orientation of the mid-substance fibres in relation to the femur did change during knee motion. During knee flexion, a fold in the ACL femoral attachment was observed at the border between the mid-substance and the fan-like extension fibres. The attachment of the mid-substance fibres was significantly smaller than the attachment of the fan-like extension fibres.

CONCLUSION

The present study clarified anatomic and histologic character of the mid-substance fibres and fan-like extension fibres, and provided critical information for future clinical and biomechanical studies concerning both two different fibres. Specifically for ACL reconstruction, it is difficult to reconstruct the natural fan-like extension fibres by creating a tunnel at the femoral and tibial ends of each fibre bundle, although the mid-substance fibres can be reconstructed by such procedures.

Joint capsule attachment to the extensor carpi radialis brevis origin: an anatomical study with possible implications regarding the etiology of lateral epicondylitis

PURPOSE

To identify the unique anatomical characteristic of the extensor carpi radialis brevis (ECRB) origin and points of differentiation from other extensors and to clarify the specific relationship of the ECRB to the underlying structures.

METHODS

We studied the origin of each extensor macroscopically for its muscular and tendinous parts; to identify the relationship between the ECRB origin and the deeper structures, we also examined the attachment of the joint capsule under the ECRB origin.

RESULTS

The ECRB simply originated as a tendon without any muscle, whereas other extensors originated as a mixture of tendon and muscle. At the anterior part of the ECRB origin, the thin attachment of the joint capsule (average width, 3.3 mm) lay deep to the ECRB and was distinct. However, at the posterodistal portion, the joint capsule, annular ligament, and supinator were intermingled and originated as a single wide sheet from the humerus (average width, 10.7 mm).

CONCLUSIONS

The anterior part of the ECRB origin was delicate, because the ECRB origin was purely tendinous, and the attachment of the articular capsule was thin compared with that of the posterodistal attachment. This thin attachment could be an initial factor leading to the development of lateral epicondylitis.

CLINICAL RELEVANCE

The results of the current study may enhance magnetic resonance imaging understanding and may help clarify the etiology of the lateral epicondylitis.

Interleukin-6 enhances manganese accumulation in SH-SY5Y cells: implications of the up-regulation of ZIP14 and the down-regulation of ZnT10

Manganese accumulation in neuronal cells may be enhanced by interleukin-6viathe up-regulation of ZIP14 and the down-regulation of ZnT10.

Down-regulation of S100A9 and S100A10 in manganese-resistant RBL-2H3 cells

Exposure to excess amounts of manganese causes toxic effects, including neurological symptoms such as Parkinsonism. However, endogenous factors involved in the protection against manganese toxicity remain unclear. Previously, we showed that rat basophilic leukemia RBL-2H3 cells are highly sensitive to MnCl₂ compared with other rat cell lines. To identify the genes involved in resistance to manganese toxicity, two lines of Mn-resistant cells showing resistance to 300 µM MnCl₂ (RBL-Mnr300) and 1200 µM MnCl₂ (RBL-Mnr1200) were developed from RBL-2H3 cells by a stepwise increase in MnCl₂ concentration in the medium. Microarray analyses were carried out to compare gene expression between parental RBL-2H3 cells and RBL-Mnr300 or RBL-Mnr1200 cells. Five genes exhibited more than 10-fold up-regulation in both RBL-Mnr300 and RBL-Mnr1200 cells, and 24 genes exhibited less than 0.1-fold down-regulation in both Mn-resistant cell lines. The S100a9 and S100a10 genes, encoding the calcium-binding S100A9 and S100A10 proteins, respectively, were found among the three most down-regulated genes in both Mn-resistant cell lines. The marked decreases in mRNA levels of S100a9 and S100a10 were confirmed by real-time RT-PCR analyses. Further characterization and comparison of these Mn-resistant cells may enable the identification of novel genes that play important roles in the modification of manganese toxicity.

Ground-state properties of the mixed-valence cobaltites Nd0.7Sr0.3CoO3, Nd0.7Ca0.3CoO3 and Pr0.7Ca0.3CoO3

The electric, magnetic, and thermal properties of three perovskite cobaltites with the same 30% hole doping and ferromagnetic ground state were investigated down to very low temperatures. With decreasing size of large cations, the ferromagnetic Curie temperature and spontaneous moments of cobalt are gradually suppressed: TC = 130 K, 55 K and 25 K and m = 0.68 μB, 0.34 μB and 0.23 μB for Nd0.7Sr0.3CoO3, Pr0.7Ca0.3CoO3 and Nd0.7Ca0.3CoO3, respectively. The moment reduction with respect to the moment of the conventional ferromagnet La0.7Sr0.3CoO3 (T(C) = 230 K, m = 1.71 μB) in the so-called low spin/intermediate spin (IS/LS) state for Co(3+)/Co(4+) was originally interpreted using a phase-separation scenario. Based on the present results, mainly the analysis of the Schottky peak originating from Zeeman splitting of the ground-state Kramers doublet of Nd(3+), we find, however, that the ferromagnetic phase in Nd0.7Ca0.3CoO3 and likely also in Pr0.7Ca0.3CoO3 is uniformly distributed over the whole sample volume, despite the severe drop of moments. The ground state of these compounds is identified with the LS/LS-related phase derived theoretically by Sboychakov et al (2009 Phys. Rev. B 80 024423). The ground state of Nd0.7Sr0.3CoO3 with an intermediate cobalt moment is inhomogeneous due to competition between the LS/LS and IS/LS phases. In the theoretical part of the study, the crystal field split levels for 4f(3) (Nd(3+)), 4f(2) (Pr(3+)) and 4f(1) (Ce(3+) or Pr(4+)) are calculated and their magnetic characteristics are presented.

Suppression of ZIP8 expression is a common feature of cadmium-resistant and manganese-resistant RBL-2H3 cells

Rat basophilic leukemia RBL-2H3 cells show markedly high sensitivity to both CdCl2 and MnCl2 compared with other rat cell lines, due to efficient accumulation of cadmium and manganese. To clarify the roles of metal transporters in hyperaccumulation of cadmium and manganese in RBL-2H3 cells, Cd-resistant and Mn-resistant cells were developed from RBL-2H3 cells by continuous exposure to CdCl2 and MnCl2, respectively. The established Cd-resistant (RBL-Cdr) and Mn-resistant (RBL-Mnr) cells exhibited about 20 times higher LC50 values of CdCl2 and MnCl2, respectively, than parental RBL-2H3 cells, and showed cross-resistance to each metal. The resistance to cadmium and manganese was primarily conferred by a marked decrease in the uptake of both metals. RBL-Cdr cells also showed cross-resistance to HgCl2 and AgNO3 probably due to enhanced expression of metallothionein. Among the possible transporters involved in the uptake of Cd(2+) and Mn(2+), the expression of ZIP8 (Zrt-, Irt-related protein 8), encoded by Slc39a8, showed a marked suppression in both RBL-Cdr and RBL-Mnr cells. These results suggest that ZIP8 plays a pivotal role in the transport and toxicity of Cd(2+) and Mn(2+) in RBL-2H3 cells.

Pathology and temporal onset of visual hallucinations, misperceptions and family misidentification distinguishes dementia with Lewy bodies from Alzheimer's disease

OBJECTIVE

To determine whether the temporal onset of visual phenomena distinguishes Lewy body disease (LBD) from Alzheimer's disease (AD), and to characterize the extent Lewy bodies and neurofibrillary tangles are associated with these clinical features.

METHODS

Consecutive cases of autopsy-confirmed LBD (n = 41), AD (n = 70), and AD with amygdala-predominant Lewy bodies (AD-ALB) (n = 14) with a documented clinical history of dementia were included. We mailed questionnaires to next-of-kin asking about symptoms during life. Lewy pathology and neurofibrillary tangle pathology were assessed.

RESULTS

The occurrence of visual hallucinations, misperceptions and family misidentification did not distinguish LBD from AD or AD-ALB, but the onset was earlier in LBD compared to AD and AD-ALB. When visual hallucinations developed within the first 5 years of dementia, the odds were 4-5 times greater for autopsy-confirmed LBD (or intermediate/high likelihood dementia with Lewy bodies) and not AD or AD-ALB. In LBD, limbic but not cortical Lewy body pathology was related to an earlier onset of visual hallucinations, while limbic and cortical Lewy body pathology were associated with visual misperceptions and misidentification. Cortical neurofibrillary tangle burden was associated with an earlier onset of misidentification and misperceptions in LBD and AD, but only with earlier visual hallucinations in AD/AD-ALB.

CONCLUSION

When visual hallucinations occur within the first 5 years of the dementia, a diagnosis of LBD was more likely than AD. Visual hallucinations in LBD were associated with limbic Lewy body pathology. Visual misperceptions and misidentification delusions were related to cortical Lewy body and neurofibrillary tangle burden in LBD and AD/AD-ALB.

Roles of ZIP8, ZIP14, and DMT1 in transport of cadmium and manganese in mouse kidney proximal tubule cells

Chronic exposure to cadmium causes preferential accumulation of cadmium in the kidney, leading to nephrotoxicity. In the process of renal cadmium accumulation, the cadmium bound to a low-molecular-weight metal-binding protein, metallothionein, has been considered to play an important role in reabsorption by epithelial cells of proximal tubules in the kidney. However, the role and mechanism of the transport of Cd(2+) ions in proximal tubule cells remain unclear. Zinc transporters such as Zrt, Irt-related protein 8 (ZIP8) and ZIP14, and divalent metal transporter 1 (DMT1) have been reported to have affinities for Cd(2+) and Mn(2+). To examine the roles of these metal transporters in the absorption of luminal Cd(2+) and Mn(2+) into proximal tubule cells, we utilized a cell culture system, in which apical and basolateral transport of metals can be separately examined. The uptake of Cd(2+) and Mn(2+) from the apical side of proximal tubule cells was inhibited by simultaneous addition of Mn(2+) and Cd(2+), respectively. The knockdown of ZIP8, ZIP14 or DMT1 by siRNA transfection significantly reduced the uptake of Cd(2+) and Mn(2+) from the apical membrane. The excretion of Cd(2+) and Mn(2+) was detected predominantly in the apical side of the proximal tubule cells. In situ hybridization of these transporters revealed that ZIP8 and ZIP14 are highly expressed in the proximal tubules of the outer stripe of the outer medulla. These results suggest that ZIP8 and ZIP14 expressed in the S3 segment of proximal tubules play significant roles in the absorption of Cd(2+) and Mn(2+) in the kidney.

Inclusion of RBD improves the diagnostic classification of dementia with Lewy bodies

OBJECTIVE

To determine whether adding REM sleep behavior disorder (RBD) to the dementia with Lewy bodies (DLB) diagnostic criteria improves classification accuracy of autopsy-confirmed DLB.

METHODS

We followed 234 consecutive patients with dementia until autopsy with a mean of 4 annual visits. Clinical diagnoses included DLB, Alzheimer disease (AD), corticobasal syndrome, and frontotemporal dementia. Pathologic diagnoses used the 2005 DLB consensus criteria and included no/low likelihood DLB (non-DLB; n = 136) and intermediate/high likelihood DLB (DLB; n = 98). Regression modeling and sensitivity/specificity analyses were used to evaluate the diagnostic role of RBD.

RESULTS

Each of the 3 core features increased the odds of autopsy-confirmed DLB up to 2-fold, and RBD increased the odds by 6-fold. When clinically probable DLB reflected dementia and 2 or more of the 3 core features, sensitivity was 85%, and specificity was 73%. When RBD was added and clinically probable DLB reflected 2 or more of 4 features, sensitivity improved to 88%. When dementia and RBD were also designated as probable DLB, sensitivity increased to 90% while specificity remained at 73%. The VH, parkinsonism, RBD model lowered sensitivity to 83%, but improved specificity to 85%.

CONCLUSIONS

Inclusion of RBD as a core clinical feature improves the diagnostic accuracy of autopsy-confirmed DLB.

High sensitivity of RBL-2H3 cells to cadmium and manganese: an implication of the role of ZIP8

Cellular incorporation of Cd involves multiple transport systems for other metals such as Fe, Zn, Mn, and Ca. Metal transporters including divalent metal transporter 1, Zrt/Irt-related protein (ZIP) 8, and ZIP14, and certain types of voltage-dependent Ca channels have been shown to be involved in cellular Cd uptake. However, tissue- or cell-specific roles of these metal transporters in the accumulation and toxicity of Cd remains unclear. In the present study, we compared the sensitivity to and accumulation of Cd, Mn, and Zn among four types of rat cell lines. Rat basophilic leukemia RBL-2H3 cells showed the highest sensitivity to Cd and Mn due to the highest accumulation of Cd and Mn among the four cell lines. The high accumulation of Cd and Mn was caused by high uptake rates of Cd and Mn. Since relatively high expression of ZIP8 and ZIP14 was found in RBL-2H3 cells, siRNAs of ZIP8 and ZIP14 were transfected into RBL-2H3 cells. The knockdown of ZIP8, but not of ZIP14, significantly reduced the uptake rates of Cd and Mn in RBL-2H3 cells, especially in the presence of bicarbonate. These results suggest that the high expression of ZIP8, which is known to have affinities for both Cd and Mn, resulted in high accumulation of Cd and Mn, leading to high sensitivity to these metals in RBL-2H3 cells. Thus, RBL-2H3 cells may serve as a good model for clarifying the mechanisms of Cd and Mn transport via ZIP8.

Chronic exposure to arsenite induces S100A8 and S100A9 expression in rat RBL-2H3 mast cells

To investigate the effects of chronic exposure to arsenite on the gene expression profiles of mast cells, microarray analysis was performed on rat basophilic leukemia RBL-2H3 cells exposed to arsenite for 28 days. Upregulated genes include calcium-binding S100 proteins such as S100A9, S100A10, S100A6, and S100A13, and granzymes B and C. Among S100 proteins, S100A9 showed the highest expression (8.62-fold of untreated cells) after 4-weeks of exposure to arsenite. As S100A8 and S100A9 comprise a heterodimer called calprotectin, and are implicated in the development of atherosclerosis and cancer, mRNA levels of both S100A8 and S100A9 were analyzed. The results demonstrated that exposure of RBL-2H3 cells to arsenite for a few weeks induces marked increases in mRNA levels of S100A8 and S100A9.

Involvement of DNA hypermethylation in down-regulation of the zinc transporter ZIP8 in cadmium-resistant metallothionein-null cells

The Zrt/Irt-related protein 8 (ZIP8) encoded by slc39a8 is now emerging as an important zinc transporter involved in cellular cadmium incorporation. We have previously shown that mRNA and protein levels of ZIP8 were decreased in cadmium-resistant metallothionein-null (A7) cells, leading to a decrease in cadmium accumulation. However, the mechanism by which ZIP8 expression is suppressed in these cells remains to be elucidated. In the present study, we investigated the possibility that epigenetic silencing of the slc39a8 gene by DNA hypermethylation is involved in the down-regulation of ZIP8 expression. A7 cells showed a higher mRNA level of DNA methyltransferase 3b than parental cells. Hypermethylation of the CpG island of the slc39a8 gene was detected in A7 cells. Treatment of A7 cells with 5-aza-deoxycytidine, an inhibitor of DNA methyltransferase, caused demethylation of the CpG island of the slc39a8 gene and enhancement of mRNA and protein levels of ZIP8. In response to the recovery of ZIP8 expression, A7 cells treated with 5-aza-deoxycytidine showed an increase in cadmium accumulation and consequently an increase in sensitivity to cadmium. These results suggest that epigenetic silencing of the slc39a8 gene by DNA hypermethylation plays an important role in the down-regulation of ZIP8 in cadmium-resistant metallothionein-null cells.

Dichotomous effects of lead acetate on the expression of metallothionein in the liver and kidney of mice

Metallothionein (MT) is a low-molecular-weight cysteine-rich protein which has a high affinity for metals and plays important roles in the protection against metal toxicity. As little information is available concerning the mechanism of MT induction by lead (Pb) compounds, we investigated the induction of MT by Pb acetate both at mRNA and protein levels in mice. Administration of Pb increased the levels of MT-I mRNA in the liver and kidney in six strains of mice. However, MT protein was detected only in the liver, and little or no increases in MT protein were detected in the kidney of any strains of mice. Speciation of metals in the liver cytosol showed that the major metal bound to MT was zinc but not Pb. The increases in plasma concentrations of interleukin-6 suggest that the production of interleukin-6 by Pb administration is involved in the induction of MT in the liver. Treatment of renal cells with Pb in vitro also resulted in the increase in MT mRNA but little increase in MT protein. These data suggest that Pb exerts a dual effect on MT expression; enhancement of MT gene transcription both in the liver and kidney and suppression of MT mRNA translation in the kidney.

Induction of metallothionein by manganese is completely dependent on interleukin-6 production

Metallothionein (MT) is a cysteine-rich protein that binds to and is inducible by heavy metals such as cadmium and zinc. However, the precise mechanism of MT induction by other metals remains unclear. In the present study, we investigated the mechanism of MT induction by manganese, focusing on the involvement of cytokine production. Administration of MnCl(2) to mice resulted in the induction of MT dose-dependently in the liver with little accumulation of manganese. Speciation analysis of metals in the liver cytosol showed that the major metal bound to the induced MT was zinc. Administration of MnCl(2) caused an increase in mRNA levels of interleukin-6 (IL-6) in the liver as well as an increase in serum levels of IL-6 but not those of other inflammatory cytokines. Subsequently, serum levels of serum amyloid A (SAA), an acute-phase protein induced by IL-6, increased with a peak at 24 h. However, no increase in serum alanine aminotransferase activity was observed, suggesting that manganese enhanced the production of IL-6 and SAA without causing liver injury. In response to IL-6, the expression of a zinc transporter, ZIP14, was enhanced in the liver, possibly contributing to the synthesis of hepatic zinc-MT. In IL-6-null mice, the induction of hepatic MT by treatment with MnCl(2) was completely suppressed to the control level. These results suggest that manganese is a unique metal that induces the synthesis of hepatic MT completely depending on the production of IL-6 without accompanying liver injury.

Helicobacter pylori infection influences symptomatic response to anti-secretory therapy in patients with GORD--crossover comparative study with famotidine and low-dose lansoprazole

BACKGROUND AND AIM

Helicobacter pylori infection was reported to affect gastric acid secretion. We investigated the heartburn symptoms of patients with gastro-oesophageal reflux disease during sequential treatment with 40 mg of famotidine or 15 mg of lansoprazole to clarify whether H. pylori infection influences symptomatic response to anti-secretory therapy.

SUBJECTS AND METHODS

The subjects were 33 gastro-oesophageal reflux disease patients, who had already been treated with a full dose of H2 receptor antagonist. First, famotidine at 20 mg b.i.d. was administered to the patients for 8 weeks. Second, famotidine was replaced with 15 mg of lansoprazole once in the morning for 8 weeks. Finally, 20 mg of famotidine was administered b.i.d. for 8 weeks instead of lansoprazole. Gastro-oesophageal reflux disease symptoms were assessed using an original visual analogue scale.

RESULTS

The sequential symptomatic responses to famotidine and lansoprazole administration indicated that gastro-oesophageal reflux disease symptoms of patients during low-dose lansoprazole treatment were significantly less than those during famotidine treatment. Remission of symptoms was obtained significantly more often by famotidine therapy in patients with H. pylori infection than in patients without H. pylori infection.

CONCLUSION

Low-dose lansoprazole is more effective than full-dose famotidine for the control of symptoms in patients with gastro-oesophageal reflux disease, and H. pylori infection influences the symptomatic response to H2 receptor antagonists.