Myocardial Depressant Effects of Desflurane: Mechanical and Electrophysiologic Actions In Vitro

Background: The authors determined whether desflurane altered myocardial excitation-contraction coupling and electrophysiologic behavior in the same manner as isoflurane and sevoflurane.

Methods: The effects of desflurane on isometric force in guinea pig ventricular papillary muscles were studied in modified standard and in 26 mm K+ Tyrode solution with 0.1 [mu]m isoproterenol. Desflurane effects on sarcoplasmic reticulum Ca2+ release were also determined by examining its actions on rat papillary muscles, guinea pig papillary muscles in low-Na+ Tyrode solution, and rapid cooling contractures. Normal and slow action potentials were recorded using a conventional microelectrode technique. Ca2+ and K+ currents of guinea pig ventricular myocytes were examined.

Results: Desflurane (5.3% and 11.6%) decreased peak force to approximately 70% and 40% of the baseline, respectively, similar to the effects of equianesthetic isoflurane concentrations. With isoproterenol in 26 mm K+ Tyrode solution, desflurane markedly depressed late peaking force and modestly depressed early peak force. The rested state contractions of rat myocardium or guinea pig myocardium in low-Na+ Tyrode solution were modestly depressed, whereas rapid cooling contractures were virtually abolished after desflurane administration. Desflurane significantly prolonged the action potential duration. Desflurane reduced L-type Ca2+ current and the delayed outward K+ current but did not alter the inward rectifier K+ current.     

Reversal of vascular 18F-FDG uptake with plasma high-density lipoprotein elevation by atherogenic risk reduction

Vascular 18F-FDG uptake marker represents inflammation in atherosclerotic lesions, but whether inflammation can be reversed by risk-modifying interventions has not, to our knowledge, been demonstrated. In this study, we evaluated the change of vascular 18F-FDG uptake in response to lifestyle intervention on serial PET/CT scans and further assessed how the findings relate to atherogenic risk reduction. METHODS: A total of 60 healthy adults underwent 18F-FDG PET/CT scans and atherogenic risk-factor assessment at baseline and again after 17.1 +/- 8.3 mo of practicing lifestyle modification. The PET/CT images were evaluated for the presence of vascular 18F-FDG lesions, and vessel-to-blood-pool 18F-FDG ratios were measured. Indices from summed ratios of positive lesions were compared and correlated to atherogenic risk factors. RESULTS: At follow-up, significant reductions in diastolic blood pressure (P < 0.05), total cholesterol (P < 0.05), and low-density lipoprotein level (P < 0.05) and an increase in high-density lipoprotein (HDL) level (P < 0.0001) were demonstrated. On the initial PET/CT scan, 50 of 60 subjects showed 1 or more 18F-FDG-positive lesions (5.9 +/- 5.0/subject), leading to a total of 352 vascular sites. On follow-up, 18F-FDG-positive lesions were significantly reduced to 2.1 +/- 2.2 sites per subject (P < 0.0001) and a total of 124 sites (64.8% reduction). Follow-up 18F-FDG-positive rates were significantly reduced for the aorta and iliac arteries. In addition, significant reductions in the whole-body 18F-FDG index from 1.39 +/- 1.23 to 0.53 +/- 0.59 (P < 0.0001) and carotid 18F-FDG index from 0.08 +/- 0.16 to 0.03 +/- 0.06 (P = 0.01) were shown. The whole-body 18F-FDG index correlated with total cholesterol (P < 0.05) and HDL level (P < 0.05), and the magnitude of reduction in the 18F-FDG index closely correlated to the amount of increase in plasma HDL level (P = 0.005). CONCLUSION: Our study demonstrated that vascular 18F-FDG uptake is reversed in response to atherogenic risk reduction by lifestyle intervention and that the magnitude of improvement correlates to increases in plasma HDL levels. Thus, serial 18F-FDG PET/CT may be useful for monitoring improvements in the inflammatory component of atherosclerotic lesions in response to risk modification.     

Uncooked rice of relatively low gelatinization degree resulted in lower metabolic glucose and insulin responses compared with cooked rice in female college students

Cooking processes that gelatinize granules or disrupt structure might increase the glucose and insulin responses because a disruption of the structure of starch by gelatinization increases its availability for digestion and absorption in the small intestine. We hypothesized that the uncooked form of rice, which has a relatively low degree of gelatinization even though in powder form, would result in lower metabolic glucose and insulin responses compared with cooked rice (CR). To assess the effects of the gelatinization of rice on metabolic response of glucose and insulin, we investigated the glucose and insulin responses to 3 rice meals of different gelatinization degree in female college students (n = 12): CR (76.9% gelatinized), uncooked rice powder (UP; 3.5% gelatinized), and uncooked freeze-dried rice powder (UFP; 5.4% gelatinized). Uncooked rice powders (UP and UFP) induced lower glucose and insulin responses compared with CR. The relatively low gelatinization degree of UPs resulted in low metabolic responses in terms of the glycemic index (CR: 72.4% vs UP: 49.7%, UFP: 59.8%) and insulin index (CR: 94.8% vs UP: 74.4%, UFP: 68.0%). In summary, UPs that were less gelatinized than CR induced low postprandial glucose and insulin responses.     

Notochordal cells stimulate migration of cartilage end plate chondrocytes of the intervertebral disc in in vitro cell migration assays

Background contextIt was recently demonstrated that the postnatal transition from a notochordal to a fibrocartilaginous nucleus pulposus (NP) is accomplished exogenously by chondrocytes migrating from hyaline cartilage end plates (CEs) into the ectopic notochordal NP region. Although our previous in vivo studies showed evidences for the migration of CE chondrocyte from hyaline CEs into the notochordal NP, it is unknown whether CE chondrocytes of the intervertebral disc (IVD) really have a motile property. In addition, the effect of notochordal cells on this property has not been elucidated.PurposeThe purpose of this in vitro study was to demonstrate whether CE chondrocytes of the IVD are capable of migration, and whether there is any biological link between notochordal cells and CE chondrocytes that may regulate the CE chondrocyte migration.Study design/settingIn vitro cell migration assays were performed using rat IVDs.MethodsNotochordal cells and chondrocytes were obtained from the NP and CE tissues, respectively, and were cultured separately. The different numbers of notochordal cells and the supernatant (conditioned medium) that contained soluble factors produced by notochordal cells were used to demonstrate their effects on the migration of CE chondrocytes. Bovine serum albumin (BSA) and lysophosphatidic acid (LPA) were used as negative and positive controls, respectively.ResultsCompared with BSA, LPA, notochordal cells (N=4×, 2×, 1×, and 0.5×10⁵), and its conditioned media (unconcentrated and fivefold concentrated) significantly increased migration of CE chondrocytes (p<.05 in all comparisons). Particularly, notochordal cells and its conditioned media increased migration in a number- and concentration-dependent manner, respectively.ConclusionsThis study demonstrates that CE chondrocytes of the IVD are capable of migration and that soluble factors produced by notochordal cells stimulate the migration. These results provide a plausible explanation to the question of why CE chondrocytes of the IVD migrate into the ectopic NP region during the natural transition from the notochordal to fibrocartilaginous NP.     

Delayed wound healing in Mac-1–deficient mice is associated with normal monocyte recruitment

The Mac-1 integrin is an important mediator of migration and inflammatory activation of neutrophils and monocytes. However, the role of Mac-1 in modulating macrophage emigration and activation and its subsequent impact on cutaneous wound healing have not been fully elucidated. To examine the significance of Mac-1 to murine wound healing, we measured epithelialization and granulation tissue formation in partial-thickness ear wounds and full-thickness head wounds, respectively, in Mac-1-deficient mice. Wounds were histologically analyzed at postwounding days 3, 5, and 7. The gap measured between the leading edges of inward-migrating granulation tissue was significantly increased in knockout mice compared with control animals at day 5 (3.8+/-0.3 vs. 2.6+/-0.5 mm; p<0.001) and day 7 (2.2+/-0.4 vs. 0.96+/-0.73 mm; p=0.005). Epithelial gap measurements were also increased in knockout mice vs. wild-type controls at days 3 (0.62+/-0.02 vs. 0.54+/-0.07 mm; p<0.05) and 5 (0.58+/-0.06 vs. 0.39+/-0.08 mm; p<0.001). Immunohistochemistry showed equal numbers of macrophages in knockout and control wounds. These findings show that Mac-1 is required for normal wound healing but that the attenuation in the deposition of granulation tissue and wound epithelialization in Mac-1 knockout mice is not associated with decreased monocyte migration into the wound.     

Inhibition of bone healing by pamidronate in calvarial bony defects.

OBJECTIVE: Pamidronate has been studied as a therapeutic drug for various osteopenic diseases. However, avascular osteonecrosis in the jawbone has been recently reported in patients receiving pamidronate. The objective of this study was to examine the effect of pamidronate on bone regeneration in a controlled animal model. MATERIALS AND METHODS: To determine the effect of parmidronate on bone healing in a local bony defect area, a rabbit calvarial bony defect model was used and poly L-lactide-co-glycolide (PLGA) used as a drug carrier material. Four defect groups were made in each rabbit calvaria and the defects were treated as follows: untreated bony defect (group 1), PLGA only (group 2), 2 mg of pamidronate with PLGA (group 3), and 3 mg of pamidronate with PLGA (group 4). Bone healing was evaluated by radiography and histology at 1, 2, 4, 6, and 8 weeks after surgery. RESULTS: In radiographic analysis, radiopacity was lower in pamidronate groups than non-operated rabbit calvarial bone at all observation points (P < .05). In histological analysis, the initial bone formation at 1 week was not different among groups, but it was much lower in the pamidronate groups than in the control or PLGA group after 2 weeks. Newly formed bone at 1 week underwent avascular necrosis after 2 weeks in both pamidronate groups. Avascular necrosis was not observed until 8 weeks in both topically applied pamidronate groups. CONCLUSION: Collectively, pamidronate inhibits bone healing in rabbit calvarial bony defect and it may explain the avascular necrosis of the jaws in patients receiving pamidronate.     

Treatment failure in intracranial primary germinomas

Object A radiation dose of 40–50 Gy is able to produce a cure rate of more than 90% in intracranial pure germinoma. However, many attempts have been made to reduce the dose and volume of radiation without compromising the disease control rate because of the toxicity of irradiation. This retrospective study is intended to provide the physician with an appropriate therapeutic strategy. Materials and methods We reviewed a series of 10 recurrent germinomas among 117 germinomas diagnosed histologically or clinically between 1979 and 2002. These patients involved underwent three different treatment modalities; radiation alone (N = 71), chemotherapy alone (N = 9), and combined therapy (N = 37). The 10-year overall and relapse-free survival rates were 97 and 93% in the radiation alone group, 89 and 67% in the chemotherapy alone group, and 92 and 92% in the combined therapy group, respectively. As expected, both radiation therapy and combined therapy were effective in controlling the disease. Tumor recurrence was closely related to the volume of radiation but not to the dose of radiation. If the tumor bed and craniospinal axis were fully covered, the radiation dose might be reduced. Chemotherapy alone showed earlier recurrence and a higher tumor recurrence rate. In the case of combined therapy, chemotherapy was useful in reducing the radiation dose but revealed some toxicity (death of two patients). Conclusions The investigation of a possible further dose reduction seems worthwhile. Radiation therapy alone with a dose of less than 40 Gy should be compared with ongoing chemotherapeutic protocols combined with low-dose irradiation.     

Fractal analysis of the PDL-bone interface and implications for orthodontic tooth movement

BACKGROUND: The periodontal ligament (PDL) is a soft tissue interposed between the tooth and the alveolar bone. It is responsible for transmission of forces in vivo; this promotes bone remodeling. The purpose our study was to use fractal analysis to quantify the complex morphology of the PDL-bone interface. METHODS: We used Scion Image (Scion Corp, Frederick, Md) and Benoit fractal analysis (Tru Soft International, St. Petersburg, Fla) programs to calculate the fractal dimension of the PDL-bone interface in rats via the box-counting method. Rats in the experimental groups received an initial force of 0.1N or 0.5N with customized springs for 6 hours. RESULTS: Our studies showed an increase in normal fractal dimension at the root apices of the rats' maxillary molars. We also found evidence that the fractal dimension varies along the entire root length from the apex to the cementoenamel junction. CONCLUSIONS: Mechanical loading might lead to an increase in fractal dimension at the PDL-bone interface apart from mechanisms of bone cell directed remodeling. These changes in fractal dimension are proportional to loading and could provide a new parameter for force determination in orthodontic tooth movement.