Effects of an automated stride assistance system on walking parameters and muscular glucose metabolism in elderly adults

OBJECTIVE

To identify the effects of an automated stride assistance system (SAS) on walking scores and muscle activities in the lower extremities of elderly people.

METHODS

Seven healthy elderly men (73-81 years) participated in this study. Subjects walked continuously at a constant speed for 50 min on a treadmill with and without the SAS, which is a device to control the walk ratio (step length/cadence) and to add support power to the thigh during walking. A step counter equipped with an infrared device was used to record walking data. The average speeds during treadmill walking were 2.89-3.82 km/h without the SAS and 3.03-4.03 km/h with the SAS. Positron emission tomography (PET) and [18F]fluorodeoxyglucose (FDG) evaluation of glucose metabolism were conducted on each subject twice after walking with and without the SAS.

RESULTS

Walk ratio, walking speed and step length were significantly improved in all subjects by the SAS, while cadence was significantly decreased by the SAS in all subjects except one. The SAS did not have a significant effect on glucose metabolism of the muscles of the lower extremities. There were no significant correlations between change in walking speed and change in glucose metabolism in each muscle without the SAS and with the SAS. In contrast, significant correlations between walking speed and glucose metabolism were shown in gluteus minimus (r = -0.929), hip-related muscles (r = -0.862), soleus (r = -0.907), and medial gastrocnemius (r = -0.952) without the SAS. With the SAS, there were significant correlations in gluteus medius (r = -0.899), hip-related muscles (r = -0.819), and medial gastrocnemius (r = -0.817) in the elderly subjects.

CONCLUSIONS

The SAS increases walking scores in elderly people without increasing energy consumption of lower-extremity muscles. The elderly subjects with low walking speed showed higher glucose metabolism in hip-related muscles and triceps surae. Thus, this association suggested that decreased walking speed in elderly adults has a higher metabolic cost in these muscle regions.

Characterization of carotid atherosclerosis and detection of soft plaque with use of black-blood MR imaging

BACKGROUND AND PURPOSE

In the treatment of carotid atherosclerosis, the rate of stenosis and characteristics of plaque should be assessed to diagnose vulnerable plaques that increase the risk for cerebral infarction. We performed carotid black-blood (BB) MR imaging to diagnose plaque components and assess plaque hardness based on MR signals.

MATERIALS AND METHODS

Three images of BB-MR imaging per plaque were obtained from 70 consecutive patients who underwent carotid endarterectomy (CEA) to generate T1- and T2-weighted images. To evaluate the relative signal intensity (rSI) of plaque components and the relationship between histologic findings and symptoms, we prepared sections at 2-mm intervals from 34 intact plaques. We then calculated the relative overall signal intensity (roSI) of 70 plaques to assess the relationship between MR signal intensity and plaque hardness and symptoms.

RESULTS

The characteristics of rSI values on T1- and T2-weighted images of fibrous cap (FC), fibrosis, calcification, myxomatous tissue, lipid core (LC) with intraplaque hemorrhage (IPH), and LC without IPH differed. Symptomatic plaques were associated with FC disruption (P < .001) and LC with IPH (P < .05). The roSI on T1-weighted images was significantly higher for soft than nonsoft plaques. When the roSI cutoff value was set at 1.25 (mean of the roSI), soft plaques were diagnosed with 79.4% sensitivity and 84.4% specificity. The roSI was also significantly higher for symptomatic than for asymptomatic plaques. Soft and nonsoft plaques as well as symptomatic and asymptomatic plaques did not significantly differ on T2-weighted images.

CONCLUSION

BB-MR imaging can diagnose plaque components and predict plaque hardness. This procedure provides useful information for planning therapeutic strategies of carotid atherosclerosis.

[Extrapleural pneumonectomy for relapsed solitary fibrous tumors of the pleura with pleural dissemination]

We report a case of a 62-year-old female with a prior thoracotomy for solitary fibrous tumor of the diaphragmatic pleura. There was no clear evidence of malignant solitary fibrous tumor of the pleura (SFTP). In the 19th postoperative month, she had a disseminated recurrence of SFTP in the left thoracic cavity. There was no evidence of metastasis from medical imaging. Accordingly, a left extrapleural pneumonectomy was performed. Pathological examination revealed a disseminated recurrence of malignant SFTP, showing a higher grade of malignancy, because the resected specimen was identical to the only section suspicious of malignancy in the previous tumor. She had no complaint and kept better performance status until the 7th postoperative month after the re-resection, when she had a recurrence in the left thoracic cavity and dissemination in the peritoneal cavity. She died of the recurrence 15 months after the re-resection and 34 months after the prior thoracotomy.

An increased incidence of Enterobacter cloacae in a cardiovascular ward

Routine surveillance in a cardiovascular ward showed that the incidence of Enterobacter cloacae isolated from sputum and oropharyngeal cultures in June 2004 increased to 27.6% (8/29) compared to 5.5% (12/219) from the rest of the hospital during the same period (OR=13.2; 95% CI 2.97-58.7; P<0.05). While an increase in E. cloacae pneumonia was not verified, an investigation was undertaken by the infection control team to prevent an outbreak. The estimate of relative risk for E. cloacae infection was based on a case-control study which measured exposure to intubation, history of a stay in the intensive care unit (ICU) and oral care between patients with E. cloacae and those negative for E. cloacae. An odds ratio of 13.2 suggested cross-contamination via the transoesophageal echocardiography (TOE) probe in the ICU prior to transfer to the cardiovascular ward. Pulsed-field gel electrophoresis and antibiogram patterns were also consistent with this hypothesis. Intervention was undertaken in the form of enforcing the disinfection of TOE probes using a 0.55% phtharal solution and the use of a single-use sheath to protect the probe from recontamination. Following intervention, the incidence rate returned to previous levels. This report illustrates the limitations in the effectiveness of current nosocomial surveillance strategies due to the retrospective nature of analysis. Improved surveillance methods such as data-mining tools specifically applicable to the institution, patient population, region and country are needed to increase the sensitivity of detecting unrecognized outbreaks, including cross-contamination.

Mesenteric transection decreases expression of interstitial cells of Cajal in an experimental model

Background

After anterior resection for rectal carcinoma patients often complain of defaecatory dysfunction. The aim of this study was to examine the number of interstitial cells of Cajal (ICCs) and ganglion cells in the distal colon partially denervated by mesenteric transection in a rat model.

Methods

Four groups of rats were operated on, a control group and three experimental groups, with increasing degree of mesenteric transection to denervate the distal colon. Animals were killed after 3 months, and the denervated colon was investigated using immunohistochemistry with Kit and protein gene product 9.5 antibodies to detect ICCs and ganglion cells respectively. Reverse transcriptase–polymerase chain reaction for c-kit and histomorphometry of muscular thickness were performed.

Results

The total number of ICCs was significantly lower in the three operated models than in the control, particularly in the histological layers of the myenteric plexus and submucosal border. There was no difference in the number of ganglion cells or changes in muscular thickness between the models.

Conclusion

The number of ICCs in rat distal colon denervated by mesenteric transection is decreased at 3 months after surgery.

Cancer targets in the Ras pathway

Ras proteins play a direct causal role in human cancer and in other diseases. Mutant H-Ras, N-Ras, and K-Ras occur in varying frequencies in different tumor types, for reasons that are not known. Other members of the Ras superfamily may also contribute to cancer. Mutations also occur in downstream pathways, notably B-Raf, PTEN, and PI 3' kinase: These pathways interact at multiple points, including cyclin D1, and act synergistically. In some cases mutations in Ras and effectors are mutually exclusive; in other cases, they coexist. Drugs blocking elements of the pathway are in different stages of clinical development. One of these, the Raf kinase/VEGF-R2 inhibitor Sorafenib, has already been approved for treatment of renal cancer and is being tested in other indications. However, therapeutic targets in the Ras pathway have not yet been fully validated as bona fide targets.

Slug expression is an independent prognostic parameter for poor survival in colorectal carcinoma patients

Slug, a member of the Snail family of transcription factors, plays a crucial role in the regulation of epithelial-mesenchymal transition (EMT) by suppressing several epithelial markers and adhesion molecules including E-cadherin. Recently, several studies have reported Slug to be expressed in breast carcinoma, oesophageal carcinoma accompanied with shorter survival. In this study, we first investigated expression of Slug mRNA in five colorectal carcinoma cell lines by reverse transcription-polymerase chain reaction. Furthermore, we investigated Slug and E-cadherin expression by immunohistochemistry in 138 patients with colorectal carcinoma. Slug mRNA was clearly expressed in four out of five colorectal carcinoma cell lines. Positive expression of Slug and E-cadherin was observed in 37 and 58% of cases, respectively. The positive expression of Slug was significantly associated with Dukes stage and distant metastasis (P = 0.0027 and 0.0007), and the positive expression of Slug had a significant impact on patient overall survival (P < 0.0001, log-rank test). Moreover, patients with positive expression of Slug and reduced expression of E-cadherin showed the worst prognosis (P < 0.0001, log-rank test). Multivariate analysis indicated that Slug expression was an independent prognostic factor. These results suggest that positive Slug expression in colorectal carcinoma patients may become a significant parameter of poor prognosis.

Function of sigma1 receptors in Parkinson's disease

OBJECTIVE

The objective of this study was to investigate the mapping of sigma1 receptors in Parkinson's disease (PD) using [11C]SA4503 and positron emission tomography (PET), and to assess whether sigma1 receptors are involved in the damaged dopaminergic system in PD patients.

MATERIALS AND METHODS

We studied seven normal volunteers and six PD patients. The low density of dopamine transporters and the normal or high density of dopamine receptors were confirmed in the putamen of all patients using [11C]CFT and [11C]RAC PET. A dynamic series of PET data acquisition was performed with arterial blood sampling. We computed the binding potential (BP) of [11C]SA4503.

RESULTS

In PD patients, the BP was significantly lower on the more affected than the less affected side of the anterior putamen, although there was no significant difference with respect to the BP between patients and controls.

CONCLUSIONS

Release of dopamine is reduced asymmetrically in the putamen of early PD. [11C]SA4503 PET is an indicator of presynaptic dopaminergic damage in PD.

Prostaglandin EP4 receptor agonist augments fixation of hydroxyapatite-coated implants in a rat model of osteoporosis

The reduced stability of hydroxyapatite (HA)-coated implants in osteopenic conditions is considered to be a major problem. We therefore developed a model of a boosted cementless implantation in osteopenic rats.

Twelve-week-old rats were either ovariectomised (OVX) or sham-operated (SO), and after 24 weeks plain or HA-coated implants were inserted. They were treated with either a prostaglandin EP4 receptor agonist (ONO-4819) or saline for one month.

The EP4 agonist considerably improved the osteoporosis in the OVX group. Ultrastructural analysis and mechanical testing showed an improvement in the implant-bone attachment in the HA-coated implants, which was further enhanced by the EP4 agonist. Although the stability of the HA-coated implants in the saline-treated OVX rats was less than in the SO normal rats, the administration of the EP4 agonist significantly compensated for this shortage. Our results showed that the osteogenic effect of the EP4 agonist augmented the osteoconductivity of HA and significantly improved the stability of the implant-bone attachment in the osteoporotic rat model.

New lidocaine ester derivatives with a prolonged anesthetic effect

In order to find a new long acting local anesthetic, methyl, ethyl, and butyl ester derivatives of lidocaine were synthesized in our laboratory. The topical anesthetic activity was studied with the effects on corneal reflex in rabbits, and the duration of action with those on the action potential of rabbit vagus nerve was studied in vitro. All drugs showed adequate topical anesthetic activities. The onset time to induce a complete blockage of the action potential in the excised vagus nerve was 97.1 +/- 6.3 s for lidocaine, 289.3 +/- 29.0 s for methyl ester, 186.3 +/- 18.4 s for ethyl ester, and 85.3 +/- 9.0 s for butyl ester. The mean duration of action, which was assessed as the time to recover from the complete block to 30% of control amplitude in a drug-free medium, was 32.5 +/- 3.1 min for lidocaine, 39.9 +/- 11.3 min for methyl ester, 68.2 +/- 4.2 min for ethyl ester, and 108.7 +/- 12.3 min for butyl ester. The differences in the duration of action between the ester derivatives and the original lidocaine were all statistically significant. The duration of action of all drugs studied paralleled with their protein binding capacities. These findings indicate the possibility that the ester derivatives studied, especially butyl ester, can be used as a long acting local anesthetic.

Histochemical evaluation for the biological effect of menatetrenone on metaphyseal trabeculae of ovariectomized rats

To evaluate the biological effects of vitamin K2 (menatetrenone, MK-4) on ovariectomy (OVX)-induced bone loss, we have examined histological alterations of femoral metaphyses of sham-operated (sham group), ovariectomized (OVX group), and MK-4 dietary-supplemented OVX (MK-4 group; 50 mg/kg per day) female Fischer rats 1, 2, 5, and 8 weeks after OVX. In the first week, rats of the OVX and MK-4 groups showed discontinuous trabeculae compared with sham-operated rats. At 2 weeks after OVX, the OVX rats revealed many large tartrate resistant acid phosphatase (TRAP)-positive osteoclasts, while osteoclasts in the MK-4-treated rats were similar in size to those of the sham group. At 5 weeks, the OVX and MK-4 groups revealed fragmented trabeculae in femoral metaphyses. The cartilage matrix was partially exposed due to stimulated bone resorption in the OVX group, but not in the MK-4 group. After 8 weeks, the OVX rats had little metaphyseal trabeculae, whereas the MK-4-treated rats had maintained short trabeculae. Despite the presence of intense alkaline phosphatase-positive osteoblasts on trabeculae in the MK-4 group, TRAP-positive osteoclasts were flattened without developing ruffled borders. Therefore, MK-4 appeared to lessen the increase in osteoclastic bone resorption induced by OVX, as well as to maintain the accelerated osteoblastic activity. It is of importance to identify the target cells for MK-4 in bone. Autoradiography localized [3H]-labeled MK-4 mainly in osteoblasts and adjacent bone matrices, but not in osteoclasts, indicating that MK-4 targets osteoblasts. Thus, MK-4 appears to target osteoblasts, consequently inhibiting bone loss induced by ovariectomy.

Healing of Implanted Expanded Polytetrafluoroethylene Vascular Access Grafts with Different Internodal Distances: A Histologic Study in Dogs

OBJECTIVE

We assessed characteristics of healing, over time, of two types of expanded polytetrafluoroethylene grafts.

STUDY DESIGN

An experimental histological study in dogs.

METHODS

The graft types studied had the same internal diameter (5 mm) but different internodal distances. In one, the internodal distance was 60 microm in the external surface and 20 microm in the luminal surface. In the other, the internodal distance was 30 microm throughout the material. Sixteen grafts of each type were implanted between the femoral artery and vein in 16 dogs; explanted 1, 2, 4 or 12 weeks later; and examined histologically.

RESULTS

In both graft types, infiltrating-cell density and maximum cell-penetration depth increased significantly between 1 and 2 weeks after implantation, but no significant increases occurred after 2 weeks. The number of inflammatory cells peaked 1 week after implantation and decreased significantly by 2 weeks. Subsequently, there were no significant changes in inflammatory cell numbers, suggesting that the inflammatory phase was over by 2 weeks after implantation and the grafts had become attached to surrounding tissue. There were no significant differences between the two graft types in cell density, cell-penetration depth, or number of inflammatory cells at any assessment time.

CONCLUSION

Our results provide histologic support for guidelines recommending that synthetic vascular grafts for hemodialysis access should not be cannulated until 2 weeks after implantation. Since increasing the internodal distance to 60 microm in the external surface had no effect on graft healing, methods other than manipulation of internodal distance should be used in developing a graft suitable for early cannulation.