Tmem2 Deficiency Leads to Enamel Hypoplasia and Soft Enamel in Mouse.

Teeth consist of 3 mineralized tissues: enamel, dentin, and cementum. Tooth malformation, the most common craniofacial anomaly, arises from complex genetic and environmental factors affecting enamel structure, size, shape, and tooth eruption. Hyaluronic acid (HA), a primary extracellular matrix component, contributes to structural and physiological functions in periodontal tissue. Transmembrane protein 2 (TMEM2), a novel cell surface hyaluronidase, has been shown to play a critical role during embryogenesis. In this study, we demonstrate Tmem2 messenger RNA expression in inner enamel epithelium and presecretory, secretory, and mature ameloblasts. Tmem2 knock-in reporter mice reveal TMEM2 protein localization at the apical and basal ends of secretory ameloblasts. Micro-computed tomography analysis of epithelial-specific Tmem2 conditional knockout (Tmem2-CKO) mice shows a significant reduction in enamel layer thickness and severe enamel deficiency. Enamel matrix protein expression was remarkably downregulated in Tmem2-CKO mice. Scanning electron microscopy of enamel from Tmem2-CKO mice revealed an irregular enamel prism structure, while the microhardness and density of enamel were significantly reduced, indicating impaired ameloblast differentiation and enamel matrix mineralization. Histological evaluation indicated weak adhesion between cells and the basement membrane in Tmem2-CKO mice. The reduced and irregular expressions of vinculin and integrin ß1 suggest that Tmem2 deficiency attenuated focal adhesion formation. In addition, abnormal HA accumulation in the ameloblast layer and weak claudin 1 immunoreactivity in Tmem2-CKO mice indicate impaired tight junction gate function. Irregular actin filament assembly was also observed at the apical and basal ends of secretory ameloblasts. Last, we demonstrated that Tmem2-deficient mHAT9d mouse ameloblasts exhibit defective adhesion to HA-containing substrates in vitro. Collectively, our data highlight the importance of TMEM2 in adhesion to HA-rich extracellular matrix, cell-to-cell adhesion, ameloblast differentiation, and enamel matrix mineralization.

Role of Heparan Sulfate in Vasculogenesis of Dental Pulp Stem Cells.

Dental pulp stem cells (DPSCs) can differentiate into vascular endothelial cells and display sprouting ability. During this process, DPSC responses to the extracellular microenvironment and cell-extracellular matrix interactions are critical in regulating their ultimate cell fate. Heparan sulfate (HS) glycosaminoglycan, a major component of extracellular matrix, plays important roles in various biological cell activities by interacting with growth factors and relative receptors. However, the regulatory function of HS on vasculogenesis of mesenchymal stem cells remains unclear. The objective of this study was to investigate the role of HS in endothelial differentiation and vasculogenesis of DPSCs. Our results show that an HS antagonist suppressed the proliferation and sprouting ability of DPSCs undergoing endothelial differentiation. Furthermore, expression of proangiogenic markers significantly declined with increasing dosages of the HS antagonist; in contrast, expression of stemness marker increased. Silencing of exostosin 1 (EXT1), a crucial glycosyltransferase for HS biosynthesis, in DPSCs using a short hairpin RNA significantly altered their gene expression profile. In addition, EXT1-silenced DPSCs expressed lower levels of endothelial differentiation markers and displayed a reduced vascular formation capacity compared with control DPSCs transduced with scrambled sequences. The sprouting ability of EXT1-silenced DPSCs was rescued by the addition of exogenous HS in vitro. Next, we subcutaneously transplanted biodegradable scaffolds seeded with EXT1-silenced or control DPSCs into immunodeficient mice. Lumen-like structures positive for human CD31 and von Willebrand factor were formed by green fluorescent protein-transduced DPSCs. Numbers of blood-containing vessels were significantly lower in scaffolds loaded with EXT1-silenced DPSCs than specimens implanted with control DPSCs. Collectively, our findings unveil the crucial role of HS on endothelial differentiation and vasculogenesis of DPSCs, opening new perspectives for the application of HS to tissue engineering and dental pulp regeneration.

Retinoic Acid Deficiency Underlies the Etiology of Midfacial Defects.

Embryonic craniofacial development depends on the coordinated outgrowth and fusion of multiple facial primordia, which are populated with cranial neural crest cells and covered by the facial ectoderm. Any disturbance in these developmental events, their progenitor tissues, or signaling pathways can result in craniofacial deformities such as orofacial clefts, which are among the most common birth defects in humans. In the present study, we show that Rdh10 loss of function leads to a substantial reduction in retinoic acid (RA) signaling in the developing frontonasal process during early embryogenesis, which results in a variety of craniofacial anomalies, including midfacial cleft and ectopic chondrogenic nodules. Elevated apoptosis and perturbed cell proliferation in postmigratory cranial neural crest cells and a substantial reduction in Alx1 and Alx3 transcription in the developing frontonasal process were associated with midfacial cleft in Rdh10-deficient mice. More important, expanded Shh signaling in the ventral forebrain, as well as partial abrogation of midfacial defects in Rdh10 mutants via inhibition of Hh signaling, indicates that misregulation of Shh signaling underlies the pathogenesis of reduced RA signaling-associated midfacial defects. Taken together, these data illustrate the precise spatiotemporal function of Rdh10 and RA signaling during early embryogenesis and their importance in orchestrating molecular and cellular events essential for normal midfacial development.

Hyaluronan metabolism in overloaded temporomandibular joint.

This study aimed to examine hyaluronan (HA) metabolism in relation to the onset and progression of temporomandibular joint osteoarthritis (TMJ-OA) induced by mechanical overloading. Two-month-old and 6-month-old C57BL/6N mice were divided into experimental and untreated control groups (n = 5/group). A sliding plate was attached to the maxillary incisors of the experimental mice for 10 days to overload the condylar cartilage in TMJ. In experimental group, profound cartilage degradation was detected in haematoxylin-eosin, Safranin-O-Fast Green-stained sections. It was also shown that the cartilage degradation was greater in older mice in both the control and the experimental groups. The number of HABP-positive cells was decreased by mechanical overloading and with age. The reduction of HA expression was correlated with the progression of cartilage degradation induced by mechanical overloading. The absolute quantification of the mRNA expression related to HA synthesis and HA degradation was also performed in each group. The mRNA expression levels of HA synthase (HAS) 2 and 3 were lower in the experimental group compared with the control group in the younger mice. In contrast, the mRNA expression levels of the HA degradation gene, HYAL2 and KIAA1199, were higher in the experimental group compared with the control group in the older mice. Thus, mechanical overload differently affected the balance of HA degradation and HA synthesis in the older and younger mice, respectively. In conclusion, mechanical overloading affects HA metabolism and it might initiate or amplify the condylar cartilage degradation.

Lactoferrin inhibits infection-related osteoclastogenesis without interrupting compressive force-related osteoclastogenesis.

BACKGROUND: Control of periodontal tissue inflammation during orthodontic treatment is very important in achieving a favourable therapeutic goal. We previously demonstrated that orally applied bovine lactoferrin (bLF) inhibited LPS-induced bone resorption but not orthodontic force-induced tooth movement in vivo. This study is designed to examine the underlying mechanism of it. METHODS: We examined the inhibitory effects of bLF on the expression of RANKL, OPG, TNF-α and COX-2 in osteoblasts loaded with compressive stress (CS) in comparison with LPS stimulated osteoblasts. Formation of osteoclasts was evaluated by co-culture system. RESULTS: Both CS- and LPS-applications upregulated COX-2 and RANKL but downregulated OPG. TNF-α was upregulated in LPS-stimulated osteoblasts but downregulated in CS-loaded osteoblasts. NS398 (a specific inhibitor of COX-2) significantly inhibited CS-induced RANKL-upregulation but not LPS-induced RANKL upregulation, indicating a critical role of COX-2/PGE2 pathway in CS-induced osteoclastogenesis. bLF significantly downregulated LPS-induced upregulation of RANKL and eliminated OPG suppression but not affected in CS-induced changes. Moreover, bLF significantly decreased LPS-induced osteoclast formation, whereas bLF had no effect on PGE2-induced osteoclast formation. CONCLUSIONS: bLF can effectively suppress harmful bone destruction associated with periodontitis without inhibiting bone remodelling by CS-loading. Therefore, oral administration of bLF may be highly beneficial for control of periodontitis in orthodontic patients.

P2X7 receptor and cytokines contribute to extra-territorial facial pain.

The whisker pad area (WP) is innervated by the second branch of the trigeminal nerve and experiences allodynia and hyperalgesia following transection of the mental nerve (MN; the third branch of the trigeminal nerve). However, the mechanisms of this extra-territorial pain remain unclear. The ionotropic P2X(7) ATP receptor (P2X(7)) in microglia is known to potentiate, via cytokines, the perception of noxious stimuli, raising the possibility that P2X(7) and cytokines are involved in this extra-territorial pain. One day after MN transection (MNT), WP allodynia/hyperalgesia developed, which lasted for > 8 wks. Activation of microglia and up-regulation of P2X(7), membrane-bound tumor necrosis factor (TNF)-α (mTNF-α), and soluble TNF-α (sTNF-α) in the trigeminal sensory nuclear complex (TNC) were evident for up to 6 wks after MNT. Allodynia/hyperalgesia after MNT was blocked by intracisternal administration of etanercept, a recombinant TNF-α receptor (p75)-Fc fusion protein. Intracisternal A438079, a P2X(7) antagonist, also attenuated allodynia/hyperalgesia and blocked up-regulation of mTNF-α and sTNF-α in the TNC. We conclude that sTNF-α released by microglia following P2X(7) activation may be important in both the initiation and maintenance of extra-territorial pain after MNT.

P2X7 receptor in the trigeminal sensory nuclear complex contributes to tactile allodynia/hyperalgesia following trigeminal nerve injury.

BACKGROUND: The present study directly addresses the roles of the P2X(7) receptor (P2X(7)R), an ionotropic adenosine triphosphate (ATP) receptor, and cytokines in the induction of orofacial pain following chronic constriction injury (CCI) of the infraorbital nerve (IoN). METHODS: Rats were anesthetized, and ligatures of 4-0 chromic gut were tied around the IoN. A438079, a P2X(7)R antagonist or SB203580, a phosphorylated (p)-p38 mitogen-activated protein kinase (MAPK) inhibitor, was infused intrathecally into CCI-treated rats. In another group of rats, 3'-O-(4-benzoylbenzoyl) adenosine 5'-triphosphate (BzATP), a P2X(7) R agonist, was infused intrathecally with A438079, SB203580 or etanercept, a tumor necrosis factor (TNF)-α receptor-binding recombinant drug. RESULTS: CCI of the IoN induced tactile allodynia/hyperalgesia and up-regulation of P2X(7)R, membrane-bound TNF-α (mTNF-α) and soluble TNF-α (sTNF-α) in the trigeminal sensory nuclear complex (TNC). Tactile allodynia/hyperalgesia or up-regulation of mTNF-α and sTNF-α in the TNC following CCI of the IoN was inhibited by A438079. SB203580 also attenuated tactile allodynia/hyperalgesia or up-regulation of mTNF-α, but not the up-regulation of sTNF-α in the TNC. Treatment of rats with BzATP induced tactile allodynia/hyperalgesia and up-regulation of sTNF-α and p-p38 in the TNC. Tactile allodynia/hyperalgesia or up-regulation of sTNF-α following BzATP treatment was inhibited by SB203580 and etanercept. CONCLUSIONS: Based on these findings, phosphorylation of p38 MAPK via P2X(7)R may induce tactile allodynia/hyperalgesia, which is most likely mediated by sTNF-α released by microglia.

Orally administered liposomal lactoferrin inhibits inflammation-related bone breakdown without interrupting orthodontic tooth movement.

BACKGROUND: Bovine lactoferrin (bLF) modulates the production of tumor necrosis factor-alpha (TNF-α) and inhibits alveolar bone breakdown associated with periodontitis. This study is designed to examine the effects of orally administered liposomal bLF (LbLF) on orthodontic force (OF)-induced alveolar bone remodeling during experimental tooth movement. METHODS: Two groups of male Wistar rats were treated with either LbLF or control solution in drinking water 7 days before OF application. Lipopolysaccharide (LPS) was injected into the gingival sulcus in half the rats in each group. Thus, four groups: OF, OF+LbLF, OF+LPS, and OF+LPS+LbLF were established. RESULTS: Orally administered LbLF significantly reduced apical migration of junctional epithelium in the OF and OF+LPS groups. In OF+LPS, osteoclast number in the alveolar crestal area was increased by LPS treatment, whereas osteoclast number was significantly reduced in OF+LPS+LbLF through suppression of TNF-α production. Osteoclastic induction in the middle part, mainly from OF application, was not affected by LbLF administration. Inhibition of tooth movement was not induced by LbLF. CONCLUSIONS: Orally administered LbLF significantly inhibits LPS-induced alveolar bone resorption but not OF-induced bone remodeling. LbLF could be a potent therapeutic and preventive agent to control periodontal inflammation in patients undergoing orthodontic treatment.

Ultrasound stimulation attenuates root resorption of rat replanted molars and impairs tumor necrosis factor-α signaling in vitro.

BACKGROUND AND OBJECTIVE: A therapeutic protocol to minimize root resorption induced by tooth replantation has not yet been universally established. In this context, noninvasive modality such as ultrasound therapy have been a focus of increased interest. This study aimed to evaluate the inhibitory effect of ultrasound therapy on root resorption of replanted rat molars. In addition, the study aimed to promote insights into the mechanism through which ultrasound mediates the metabolism of periodontal cells in vitro. MATERIAL AND METHODS: An experimental model of tooth replantation in rats, involving luxation and immediate replacement of the maxillary first molars, was used to assess the inhibitory effect of an ultrasound-therapy regimen (15 min of exposure to ultrasound, each day for 21 d) on root resorption. Moreover, the effect of ultrasound on osteoclastogenesis/cementoclastogenesis was examined in vitro using a mouse osteoblastic stromal cell line (ST2) and a mouse cementoblastic cell line (OCCM-30). RESULTS: The area of root resorption lacunae was statistically decreased (p < 0.01) in the ultrasound-treated sample. In addition, immunohistochemical staining, using murine TNF-α polyclonal antibody, failed to detect tumor necrosis factor-α (TNF-α) protein in the ultrasound-treated sample compared with the control. An in vitro study showed that the lipopolysaccharide (LPS)-induced expression of Tnfalpha mRNA was significantly reduced by ultrasound therapy in both osteoblastic and cementoblastic cells. Moreover, the TNF-α-induced up-regulation of Rankl mRNA was also inhibited by ultrasound. CONCLUSION: Ultrasound may contribute to the reduction of the trauma-induced inflammatory reaction through impairment of the TNF-α signaling pathway. It is therefore suggested that ultrasound shows potential as a therapeutic tool to optimize the regenerative potential of periodontal tissues on replanted teeth.

In vivo detection of amyloid ß deposition using ¹9F magnetic resonance imaging with a ¹9F-containing curcumin derivative in a mouse model of Alzheimer's disease.

Amyloid ß (Aß) deposition in the brain is considered the initiating event in the progression of Alzheimer's disease (AD). Amyloid imaging is widely studied in diagnosing AD and evaluating the disease stage, with considerable advances achieved in recent years. We have developed a novel ¹9F-containing curcumin derivative (named FMeC1) as a potential imaging agent. This compound can exist in equilibrium between keto and enol tautomers, with the enol form able to bind Aß aggregates while the keto form cannot. This study investigated whether FMeC1 is suitable as a ¹9F magnetic resonance imaging (MRI) probe to detect Aß deposition in the Tg2576 mouse, a model of AD. In ¹9F nuclear magnetic resonance (NMR) spectra obtained from the whole head, a delayed decreased rate of F ¹9F signal was observed in Tg2576 mice that were peripherally injected with FMeC1 in comparison to wild-type mice. Furthermore, ¹9F MRI displayed remarkable levels of ¹9F signal in the brain of Tg2576 mice after the injection of FMeC1. Histological analysis of FMeC1-injected mouse brain showed penetration of the compound across the blood-brain barrier and binding to Aß plaques in peripherally injected Tg2576 mice. Moreover, the distribution of Aß deposits in Tg2576 mice was in accordance with the region of the brain in which the ¹9F signal was imaged. FMeC1 also exhibited an affinity for senile plaques in human brain sections. These findings suggest the usefulness of FMeC1 as a ¹9F MRI probe for the detection of amyloid deposition in the brain. Furthermore, the properties of FMeC1 could form the basis for further novel amyloid imaging probes.

Effects of ultrasound on the proliferation and differentiation of cementoblast lineage cells.

BACKGROUND: The purpose of this study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) stimulation on the proliferation and differentiation of cementoblast lineage cells. METHODS: An immortalized human periodontal ligament cell line (HPL) showing immature cementoblastic differentiation was used. Cultured HPL cells were subjected to LIPUS exposure (frequency = 1 MHz; pulsed 1:4; intensity = 30 mW/cm(2)) or sham exposure for 15 minutes per day. Expression levels of alkaline phosphatase (ALP), type I collagen (Col-I), runt-related gene 2 (Runx2), bone sialoprotein (BSP), osteocalcin (OCN), and osteopontin (OPN) mRNA were analyzed with real-time polymerase chain reaction analysis. Furthermore, ALP activity, collagen synthesis, and protein level of Runx2 were examined after 6 days of LIPUS exposure. RESULTS: mRNA and protein levels of ALP, Col-I, and Runx2 were significantly increased by LIPUS exposure compared to controls, whereas BSP, OCN, and OPN mRNA expression could not be detected in HPL cells, irrespective of LIPUS exposure. CONCLUSION: LIPUS enhanced ALP activity, collagen synthesis, and Runx2 expression of HPL cells, which provides important insight into the promotion of early cementoblastic differentiation of immature cementoblasts.

Dynamic compressive properties of the mandibular condylar cartilage.

The mandibular condylar cartilage plays an important role as a stress absorber during function. However, relatively little information is available on its dynamic properties under compression. We hypothesized that these properties are region-specific and depend on loading frequency. To characterize the viscoelastic properties of the condylar cartilage, we performed dynamic indentation tests over a wide range of loading frequencies. Ten porcine mandibular condyles were used; the articular surface was divided into 4 regions, anteromedial, anterolateral, posteromedial, and posterolateral. The dynamic complex, storage, and loss moduli increased with frequency, and these values were the highest in the anteromedial region. Loss tangent decreased with frequency from 0.68 to 0.17, but a regional difference was not found. The present results suggest that the dynamic compressive modulus is region-specific and is dependent on the loading frequency, which might have important implications for the transmission of load in the temporomandibular joint.

Comparison of MR images and histochemical localization of intra-arterially administered microglia surrounding beta-amyloid deposits in the rat brain.

The therapeutic use of microglial cells has recently received some attention for the treatment of Alzheimer disease (AD), but few non-invasive techniques exist for monitoring the cells after administration. Here we present a magnetic resonance imaging (MRI) technique for tracking microglia injected intra-arterially in vivo. We micro-injected Abeta42 into the left hippocampus and saline into the right hippocampus of rats. We then administered microglia, which were labeled with enhanced green fluorescent protein (EGFP) gene and Resovist, into the carotid artery. After monitoring exogenously administered microglia using MRI, we compared the MR images and the histochemical localization of administered microglia. MRI revealed clear signal changes attributable to Resovist-containing microglia in Abeta-injected areas. Histochemistry demonstrated that EGFP-positive microglia accumulated around Abeta deposits and internalized the peptide. This study demonstrates the usefulness of MRI for non-invasive monitoring of exogenous microglia, and suggests a promising future for microglia/macrophages as therapeutic tools for AD.

Use of real-time magnetic resonance image guidance in endoscopic sinus surgery.

We evaluated the effectiveness of magnetic resonance image (MRI) guidance using an optical tracking system (MRI-guided therapy: MRT) in performing endoscopic sinus surgery (ESS). The profiles of the fourteen patients in the present study were as follows: eleven with mucocele in the paranasal sinus, one with recurrent chronic sinusitis, one with maxillary cancer, and one with Graves' ophthalmopathy. Preparation of the MRT system required an additional 54 min in cases involving general anesthesia, and an additional 17 min in cases involving local anesthesia, in comparison with corresponding control groups undergoing ESS in a traditional operating room. We developed nonmetal probes that were visualized in a real-time mode and assistive devices for the optical tracking system that were equipped to avoid obstruction caused by surgical instruments as well as by the hands of surgeons. Using these unique devices, anatomic landmarks were visualized using the present MRT system. The prognosis of patients was favorable, and in particular, no patients with sinus mucocele showed a recurrence of their lesions. We concluded that the MRT system used here for performing ESS was beneficial, especially in terms of the intranasal marsupialization of sinus mucoceles and for the verification of orbital contents.

Magnetic resonance spectroscopic determination of a neuronal and axonal marker in white matter predicts reversibility of deficits in secondary normal pressure hydrocephalus.

BACKGROUND: Normal pressure hydrocephalus (NPH) is considered to be a treatable form of dementia, because cerebrospinal fluid (CSF) shunting can lessen symptoms. However, neuroimaging has failed to predict when shunting will be effective. OBJECTIVE: To investigate whether 1H (proton) magnetic resonance (MR) spectroscopy could predict functional outcome in patients after shunting. METHODS: Neurological state including Hasegawa's dementia scale, gait, continence, and the modified Rankin scale were evaluated in 21 patients with secondary NPH who underwent ventriculo-peritoneal shunting. Outcomes were measured postoperatively at one and 12 months and were classified as excellent, fair, or poor. MR spectra were obtained from left hemispheric white matter. RESULTS: Significant preoperative differences in N-acetyl aspartate (NAA)/creatine (Cr) and NAA/choline (Cho) were noted between patients with excellent and poor outcome at one month (p = 0.0014 and 0.0036, respectively). Multiple regression analysis linked higher preoperative NAA/Cr ratio, gait score, and modified Rankin scale to better one month outcome. Predictive value, sensitivity, and specificity for excellent outcome following shunting were 95.2%, 100%, and 87.5%. Multiple regression analysis indicated that NAA/Cho had the best predictive value for one year outcome (p = 0.0032); predictive value, sensitivity, and specificity were 89.5%, 90.0%, and 88.9%. CONCLUSIONS: MR spectroscopy predicted long term post-shunting outcomes in patients with secondary NPH, and it would be a useful assessment tool before lumbar drainage.

Effects of propofol on lactate accumulation and oedema formation in focal cerebral ischaemia in hyperglycaemic rats.

BACKGROUND: In cerebral ischaemia, hyperglycaemia brings about severe lactate accumulation and neuronal damage when compared with normoglycaemia. Propofol has been known to suppress glucose metabolism in the brain and possess neuroprotective properties in cerebral ischaemia. Therefore, in this study we examined if propofol could attenuate lactate accumulation and neuronal damage in cerebral ischaemia under hyperglycaemic conditions. METHODS: Ten male wistar rats were divided into two experimental groups: low-dose (approximately 12 mg kg(-1) h(-1)) and high-dose (approximately 60 mg kg(-1) h(-1)) propofol groups (n=5 for each). Following injection of 2 g kg(-1) glucose intraperitoneally, the middle cerebral artery was occluded for 1 h, and then reperfused for the following 2 h. Lactate accumulation and oedema formation were estimated consecutively using nuclear magnetic resonance (NMR) techniques. RESULTS: Lactate accumulation and oedema formation increased continuously during ischaemia and reperfusion in the low-dose propofol group, which was attenuated in the high-dose propofol group. Lactate/NAA (N-acetylaspartate) ratio (as an index of lactate accumulation) 60 and 120 min after reperfusion were 2.67 and 3.26 in low-dose group and 0.30 and 0.10 in high-dose group. For NMR images the number of pixels with a low average diffusion coefficient (an index of the oedema formation), 60 and 120 min after reperfusion were 250.0 and 317.8 in low-dose group, and 16.0 and 12.4 in high-dose group. CONCLUSION: High-dose propofol attenuated lactate accumulation and oedema formation in cerebral ischaemia in hyperglycaemic rats.

Increased arterial wall stiffness limits flow volume in the lower extremities in type 2 diabetic patients.

OBJECTIVE: To document an association between arterial wall stiffness and reduced flow volume in the lower-extremity arteries of diabetic patients. RESEARCH DESIGN AND METHODS: We recruited 60 consecutive type 2 diabetic patients who had no history or symptoms of peripheral arterial disease (PAD) in the lower extremities and normal ankle/brachial systolic blood pressure index at the time of the study (non-PAD group) and 20 age-matched nondiabetic subjects (control group). We used an automatic device to measure pulse wave velocity (PWV) in the lower extremities as an index of arterial wall stiffness. At the popliteal artery, we evaluated flow volume and the resistive index as an index of arterial resistance to blood flow using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. RESULTS: Consistent with previous reports, we confirmed that the non-PAD group had an abnormally higher PWV compared with that of the control group (P < 0.001). To further demonstrate decreased flow volume and abnormal flow pattern at the popliteal artery in patients with a higher degree of arterial wall stiffness, we assigned the 60 non-PAD patients to tertiles based on their levels of PWV. In the highest group, magnetic resonance angiograms of the calf and foot arteries showed decreased intravascular signal intensity, indicating the decreased arterial inflow in those arteries. The highest group was also characterized by the lowest late diastolic and total flow volumes as well as the highest resistive index among the groups. From stepwise multiple regression analysis, PWV and autonomic function were identified as independent determinants for late diastolic flow volume (r(2) = 0.300; P < 0.001). CONCLUSIONS: Arterial wall stiffness was associated with reduced arterial flow volume in the lower extremities of diabetic patients.

Fast (13)C-glucose metabolite mapping in rat brain using (1)H echo planar spectroscopic imaging technique at 2T.

For fast (13)C metabolite mapping in rat brains, (1)H-detected (13)C NMR spectroscopy using gradient-enhanced heteronuclear multiple-quantum coherence and (1)H echo planar spectroscopic imaging were combined. (13)C glucose and 3-/4-(13)C-Glu/Gln images of rat brain were successfully constructed with 35-minute temporal resolution under a 2T magnetic field. In the ischemic region of the suture middle cerebral artery occlusion model, glucose and Glu/Gln signals decreased and lactate signals appeared. J. Magn. Reson. Imaging 2001;13:787-791.

Usefulness of waveform analysis of popliteal artery in type II diabetic patients using gated magnetic resonance 2D-cine-PC imaging and 31P spectroscopy.

AIMS/HYPOTHESIS: We studied 76 patients with Type II (non-insulin-dependent) diabetes mellitus and 16 age-matched non-diabetic subjects (control group) to clarify qualitative and quantitative abnormalities of waveform and flow volume of the popliteal artery. METHODS: The 76 diabetic patients comprised 16 patients with occlusive arterial disease in the lower extremities [arteriosclerosis obliterans (ASO) group] and 60 patients free from this disease (non-ASO group). We flow analysed the popliteal artery and measured the phosphocreatine to inorganic phosphate ratio of resting plantar muscles to identify risk factors for foot lesions using gated magnetic resonance two-dimensional cine-mode phase-contrast imaging and 31P spectroscopy. RESULTS: The control and non-ASO groups had a triphasic waveform with systolic, early and late diastolic components. All ASO patients had an abnormal monophasic waveform and a lower ankle brachial index than that of the control and non-ASO groups. To clarify the mechanism of reduced flow volume of lower extremities, we assigned the 60 patients of the non-ASO group to the three subgroups based on their levels of total flow volume of the popliteal artery. The lowest group showed an abnormal triphasic waveform with lower amplitudes of systolic and late diastolic components and flow velocities in foot arteries than those of the highest group although ABI was similar. From stepwise multiple regression analysis, late diastolic flow volume was identified as an independent determinant for the phosphocreatine to inorganic phosphate ratio (r2 = 0.484, p < 0.001). CONCLUSION/INTERPRETATION: Waveform analysis of popliteal artery provides a powerful tool for identifying impaired peripheral circulation caused by either occlusive arterial disease or increased arterial resistance in diabetic patients.