Effect of intermittent parathyroid hormone (1-34) treatment on the bone response after placement of titanium implants into the tibia of ovariectomized rats.

PURPOSE: This study investigated the effect of parathyroid hormone (1-34) [PTH(1-34)] on bone reactions after tibial placement of titanium screw implants into ovariectomized rats. MATERIALS AND METHODS: Twelve-week-old female Wistar rats were divided into 3 groups of 24. The first group (Sham group) was sham-operated; the second group (OVX group) was ovariectomized only; and the third group (PTH group) was subcutaneously administered 30 microg/kg PTH in the dorsal region 3 days per week starting the fourth week after ovariectomy until the end of the experiment. Titanium screw implants were placed in the proximal metaphysis of the tibia of all 3 groups at 168 days after surgery. The animals were killed 7, 14, 28, and 56 days after implantation. Undecalcified sections were prepared and evaluated by light microscopy. Histomorphometric measurements were obtained using a computer-based image analyzer to quantify the unit bone mass around the implant and the rate of implant-bone contact. RESULTS: When PTH administration was started 21 days after ovariectomy, the volume density of bone around implants in the PTH group was almost the same as that of the Sham group throughout the entire observation period. This finding suggests that not only can intermittent human PTH(1-34) administration prevent resorption of newly generated trabeculae around an implant but also it can aid in the recovery of bone volume lost due to ovariectomy. CONCLUSION: When dental implants are applied to jaw bone showing trabecular bone loss, it may be possible to increase bone density around an implant by intermittent human PTH(1-34) administration and thereby improve clinical results.     

Quadro-pulse stimulation is more effective than paired-pulse stimulation for plasticity induction of the human motor cortex

OBJECTIVE: Repetitive paired-pulse transcranial magnetic stimulation (TMS) at I-wave periodicity has been shown to induce a motor-evoked potential (MEP) facilitation. We hypothesized that a greater enhancement of motor cortical excitability is provoked by increasing the number of pulses per train beyond those by paired-pulse stimulation (PPS). METHODS: We explored motor cortical excitability changes induced by repetitive application of trains of four monophasic magnetic pulses (quadro-pulse stimulation: QPS) at 1.5-ms intervals, repeated every 5s over the motor cortex projecting to the hand muscles. The aftereffects of QPS were evaluated with MEPs to a single-pulse TMS, motor threshold (MT), and responses to brain-stem stimulation. These effects were compared to those after PPS. To evaluate the QPS safety, we also studied the spread of excitation and after discharge using surface electromyograms (EMGs) of hand and arm muscles. RESULTS: Sizes of MEPs from the hand muscle were enhanced for longer than 75min after QPS; they reverted to the baseline at 90min. Responses to brain-stem stimulation from the hand muscle and cortical MEPs from the forearm muscle were unchanged after QPS over the hand motor area. MT was unaffected by QPS. No spreads of excitation were detected after QPS. The appearance rate of after discharges during QPS was not different from that during sham stimulation. CONCLUSIONS: Results show that QPS can safely induce long-lasting, topographically specific enhancement of motor cortical excitability. SIGNIFICANCE: QPS is more effective than PPS for inducing motor cortical plasticity.     

A patient with a traumatic right diaphragmatic hernia occurring 4 years after sustaining injury--statistical observations of a delayed diaphragmatic hernia caused by uncomplicated injury in Japan.

We describe our experience with a patient in whom a traumatic right diaphragmatic hernia developed 4 years after sustaining injury and review cases of delayed diaphragmatic injury reported in Japan. The patient was a 28-year-old man who sustained a severe contusion of the right epigastric region and fractured a right rib in a traffic accident in September 1992. In August 1996, the patient presented with shortness of breath on effort or after meals. A chest roentgenogram revealed intestinal gas in the right side of the thoracic cavity. A right diaphragmatic hernia was diagnosed on the basis of a gastrointestinal series, and the patient was operated on. The hernial orifice extended anteriorly from the central tendon in an 11:00 direction and measured 11 x 6 cm. The small intestine, right side of the colon, and liver were herniated. A total of 297 cases of blunt traumatic diaphragmatic hernia were reported in Japan between 1981 and 1996, including 47 cases (left side, 32 cases; right side, 15 cases) of delayed diaphragmatic hernia, defined as occurring one month or more after injury. Diaphragmatic hernia should be considered as a possible diagnosis in patients with abnormal shadows in the thoracic region who have recently sustained injury or who have a past history of injury.     

Efficacy of radiofrequency catheter ablation in a patient with sinus node reentrant tachycardia

We performed electrophysiological study and catheter ablation on a 62-year-old patient with supraventricular tachycardia(SVT). This SVT was reproducibly initiated and terminated by atrial stimulation during the electrophysiological testing. The P-wave morphology and atrial activation sequence of intracardiac electrograms were identical to those in normal sinus rhythm. SVT was terminated with carotid sinus massage that increased vagal tone, and for this reason, the reentry circuit of SVT could be localized in sinus node. On the basis of these findings, the SVT was diagnosed as sinus node re-entrant tachycardia and was successfully eliminated by radiofrequency catheter ablation. Radiofrequency catheter ablation would be effective in patients with sinus node reentrant tachycardia refractory to anti-arrhythmic drugs. It should, however, be performed with careful consideration to the influence of the sinus node.     

Role of Laryngeal Movement and Effect of Aging on Swallowing Pressure in the Pharynx and Upper Esophageal Sphincter

Objectives Describe contribution of laryngeal movement to pressure changes at the upper esophageal sphincter (UES) and the effect of aging on the swallowing function. Study Design Manofluorography on 56 nondysphagic adults divided into three age groups: the 21‐ to 31‐year‐old group (n = 32), the 61‐ to 74‐year‐old group (n = 12) and the 75‐ to 89‐year‐old group (n = 12). Analyses of the bolus transit time, the amplitudes and durations of pharyngeal pressures, the timing of a pressure fall at the UES and the laryngeal movements. Methods Intraluminal strain‐gauge sensors recorded pressure changes in the oropharynx, hypopharynx and the UES. Motion pictures of the videotapes were fed into a personal computer, and movements of the hyoid bone were measured in both the horizontal and vertical directions as an indication of laryngeal movement. Results In 26‐ and 70‐year‐old men with calcification of the thyroid cartilage, it was determined that the larynx and hyoid bone moved in consonance until the end of the rapid hyoid movements in both the superior and anterior directions. In the 21‐ to 31‐year‐old group, the magnitude of the pressure fall at the UES was maximal before or almost at the same time as the bolus arrival, in preparation for smooth passage of the bolus from the pharynx to the esophagus. The rapid superior movements of the hyoid bone started significantly early as compared with its anterior movements (P = .0001). The rapid anterior movements of the hyoid bone started simultaneously with the pressure fall at the UES. In the elderly, all segmental transit times were significantly increased. The timing of the pressure fall at the UES was significantly delayed and the UES pressure reached its minimum value after arrival of the bolus at the UES. The minimum pressure at the UES increased to a significantly positive value. The rapid anterior movements of the hyoid were significantly delayed, suggesting that this delay causes the delay in the pressure fall at the UES. Conclusions The rapid superior and anterior movements of the hyoid bone are considered to start at the same time as those of the larynx. In the young group, it is suggested that superior laryngeal movement protects the lower airway prior to the anterior laryngeal movement, causing the pressure fall at the UES to enable the passage of a bolus into the UES. In the elderly, smooth passage of the bolus from the pharynx to the esophagus is hindered and the system that prevents aspiration is rendered inefficient by changes in the swallowing pressures and laryngeal movements with aging.     

Differential responses of the hypothalamo-pituitary-adrenocortical axis to acute restraint stress in Hatano high- and low-avoidance rats

The high- and low-avoidance animal (HAA and LAA respectively) strains of Hatano rats were originally selected and bred from Sprague-Dawley rats for their performance in the shuttle-box task. The present study focused on the activity of the hypothalamo-pituitary-adrenocortical (HPA) axis of HAA and LAA rats in response to restraint stress. The restraint stress induced an elevation in plasma concentrations of ACTH, prolactin, corticosterone and progesterone. Peak levels of plasma ACTH during stress conditions were significantly higher in HAA rats than in LAA rats, while peak levels of prolactin were significantly lower in HAA rats than in LAA rats. Under stress conditions, ACTH and prolactin synthesis in the anterior pituitary glands was significantly higher in HAA rats compared with LAA rats. The peak plasma concentrations of corticosterone, during restraint stress, were significantly higher in LAA rats compared with HAA rats. These results indicate that the response of the hypothalamo-pituitary axis to acute restraint stress is greater in HAA rats than in LAA rats, whereas the ACTH-induced adrenal response of corticosterone release is higher in LAA rats than in HAA rats. On the other hand, prolactin secretory activity is higher in LAA rats compared with HAA rats. These differences in endocrine responses to stress may be involved in the regulation of the avoidance responses in the shuttle-box task.     

A prospective, single-blind trial comparing wireless capsule endoscopy and double-balloon enteroscopy in patients with obscure gastrointestinal bleeding

BACKGROUND: Wireless capsule endoscopy (CE) and double-balloon enteroscopy (DBE) are new methods enabling diagnostic endoscopy of the entire small intestine. However, which of the two is superior is unclear. We therefore prospectively compared the clinical efficacy of CE and DBE. METHODS: We prospectively examined 32 patients with obscure gastrointestinal bleeding. CE preceded DBE by 1-7 days, and all patients underwent DBE twice, by antegrade and retrograde approaches, to evaluate the entire small intestine. Physicians evaluating the results of CE and DBE were blind to the results of the other method. We evaluated diagnosis, diagnostic yield of the two methods, and clinical outcomes. RESULTS: CE revealed abnormal findings in 29 (90.6%) of 32 patients. CE definitively or probably detected the sources of bleeding in 23 (71.9%) of the 32 patients, including angioectasias (eight), erosions (seven), ulcers (five), tumor (one), and hemorrhagic polyps (two). DBE definitely or probably detected the sources of bleeding in 21 (65.6%) of the 32 patients, including angioectasias (seven), erosions (four), ulcers (five), tumor (one), hemorrhagic polyps (two) and diverticula (two). CE yielded more abnormal findings than DBE (CE 90.6%, DBE 65.6%) (P = 0.032), although there were no significant differences in diagnostic yield between the methods. We were able to perform additional treatment or biopsy with DBE in 13 patients, including coagulation therapy (ten), endoscopic mucosal resection (one), biopsy (seven), and extraction of retained CE (two). CONCLUSIONS: Our results demonstrate the superiority of CE in detecting abnormal lesions, and the superiority of DBE in endoscopic management.     

Left ventricular oxygen utilization efficiency is impaired in chronic streptozotocin-diabetic sheep

OBJECTIVE: Energy metabolism is altered in the diabetic heart. However, direct in vivo evidence that diabetes impairs energetics at the chamber level is lacking. Therefore, we investigated the effect of diabetes on left ventricular (LV) energetics in a chronic ovine model. METHODS: Diabetes was induced in Merino-cross sheep with streptozotocin. Experiments were performed in five animals following 12 months untreated diabetes and six animals served as controls. Open-chest anesthetized sheep were instrumented to determine the LV pressure-volume relationship, oxygen consumption and free fatty acid uptake. RESULTS: Diabetes impaired LV contractility (1.5+/-0.5 vs. 2.3+/-0.5 mmHg/ml, P<0.01). Stroke work was preserved but stroke work efficiency (stroke work/pressure-volume area) deteriorated (52+/-4 vs. 58+/-3%, P<0.01). Plasma free fatty acid levels increased (1885+/-1078 vs. 354+/-203 mmol/l, P<0.01) as did LV free fatty acid uptake (312+/-278 vs. 90+/-47 micromol/beat per 100 g LV, P=0.04). Contractile efficiency decreased (31.9+/-1.4 vs. 50.0+/-8.7%, P<0.01) while unloaded oxygen consumption did not change significantly. Therefore, LV oxygen utilization efficiency (stroke work/LV oxygen consumption) was compromised in the diabetic heart (14.9+/-2.8 vs. 24.3+/-4.0%, P<0.001). CONCLUSION: This is the first study to demonstrate that diabetes alters ventricular energetics in vivo. LV oxygen utilization efficiency is impaired as a consequence of decreased contractile efficiency and stroke work efficiency. Impaired efficiency of oxygen utilization may explain in part the increased sensitivity of the diabetic heart to ischemia and the accelerated deterioration of ventricular function in diabetic patients.