Use of cerebral oximetry to monitor brain oxygenation reserves for skull base surgery

We used cerebral oximetry based on near-infrared re-emittance spectroscopy for noninvasive evaluation of the cerebral regional oxygen saturation (rSO(2)) to preoperatively assess patients with skull base tumors and giant arterial aneurysms, for whom possible occlusion or partial resection of the internal carotid artery was considered. Monitoring cerebral oxygen saturation was performed during both endovascular (balloon) and open surgical test occlusions of the internal carotid artery. The presence (or absence) of changes in the cerebral oxygen saturation served as a criterion of the patient's tolerance to permanent occlusion of the internal carotid artery. In all cases the curves of saturation accurately corresponded to the clinical condition of the patients, primarily to the developing of neurological signs. Cerebral oximetry was an extremely informative and reliable technique for fast, easy, and noninvasive detection of changes in brain blood circulation. Generally, cerebral oximetry serves as a valuable adjunct in detection of brain tolerance to the occlusion of major arterial vessels and in monitoring the condition of the brain in regard to its oxygenation and perfusion.

Long-term instrumental parameter investigation of a Fabry-Perot spectrometer at an isolated field station

To insure that long-term determinations of Doppler width and shift--derived from observations of atmospheric emissions--are internally consistent and reliable, we have developed a method to both continuously and nonintrusively determine and monitor the instrumental constants of the Fabry-Perot spectrometer making the observations. We have used this method at our isolated field experiment at South Pole, Antarctica, because the instrument is only accessible to us for a few days every year. Here we report both the method and the Fabry-Perot stability results for the past 22 years of operation. The method involves the description of real Fabry-Perot instrumental constants as a small departure from those of an ideal Fabry-Perot. In general, this model is applicable for most observations. However, experimentally, there are times when the small-departure model is not applicable, thus indicating how to best reduce the observations into physical quantities for the utmost consistency in the geophysical results.

[Diagnostic value and functional correlations of the ADAS-Cog scale in Alzheimer's disease: data on NORMACODEM project]

INTRODUCTION

The aims of this study were to assess the criterion validity of Alzheimer's Disease Assessment Scale (ADAS) and its cognitive subscale (ADAS-Cog) for the diagnosis of Alzheimer's disease (AD), and to determine their different cut-off scores and sensitivity and specificity values. In addition, we also attempted to study the possible correlations between cognitive scores (ADAS) and functional measures.

METHODS

451 subjects were studied (254 controls, 86 subjects with mild cognitive impairment and 111 patients with AD). ADAS total score was obtained by adding the cognitive (ADAS-Cog) and non-cognitive (ADAS-Nocog) scales. Scores were adjusted for age and formal education. For assessing the possible correlation between cognitive and functional measures, the following instruments were administered: Rapid Disability Rating Scale-2 (RDRS-2), Blessed Dementia Rating Scale (BDRS) and the Interview for the Deterioration of Daily Living in Dementia (IDDD).

STATISTICAL ANALYSIS

ROC curves and Pearson correlation coefficient.

RESULTS

ADAS best cut-off score for dementia was > or = 17 providing sensitivity and specificity values of 90.09% and 85.88 % respectively, while for the ADAS-Cog best cut-off score was > or = 12 with sensitivity and specificity values of 89.19 % and 88.53 % respectively. In both cases scores were adjusted for age and formal education. The area under the ROC curve was 0.95 and 0.94 respectively. Highly significant correlations were found for ADAS and 19 ADAS-Cog with the functional scales studied.

CONCLUSIONS

Both, ADAS and ADAS-Cog report good validity in terms of sensitivity, specificity and as predictive value for AD. Moreover, significant correlations were found between the functional impairment observed in patients with AD and the overall scores achieved in the ADAS and ADAS-Cog.

Validation of an 8-14 microm cloud monitor using visual observations of Antarctic cloud cover

A cloud monitor instrument, sensing 8-14 microm infrared radiation, has been installed near McMurdo, Antarctica, in order to provide supporting cloud cover information for a high-resolution sky-viewing Fabry-Perot spectrometer experiment. Validation of the cloud monitor observations was performed by a 1 year long comparison with the available 6 h visual cloud observations, expressed in octas (obscured eighths of the sky). The agreement between visual observations and those of the cloud monitor is good--the variation being slightly over one step, or octa--except at the clear sky extreme, which the subjective visual observations tend to overestimate during dark and moonless conditions. Both visual observations and the cloud monitor measurements show an austral winter-summer difference with the winter being clearer.

TRPV1 receptors in the CNS play a key role in broad-spectrum analgesia of TRPV1 antagonists

Vanilloid receptor type 1 (TRPV1) is a ligand-gated nonselective cation channel that is considered to be an important integrator of various pain stimuli such as endogenous lipids, capsaicin, heat, and low pH. In addition to expression in primary afferents, TRPV1 is also expressed in the CNS. To test the hypothesis that the CNS plays a differential role in the effect of TRPV1 antagonists in various types of pain, the analgesic effects of two TRPV1 antagonists with similar in vitro potency but different CNS penetration were compared in vivo. Oral administration of either A-784168 (1-[3-(trifluoromethyl)pyridin-2-yl]-N-[4-(trifluoromethylsulfonyl)phenyl]-1,2,3,6-tetrahydropyridine-4-carboxamide) (good CNS penetration) or A-795614 (N-1H-indazol-4-yl-N'-[(1R)-5-piperidin-1-yl-2,3-dihydro-1H-inden-1-yl]urea) (poor CNS penetration) blocked capsaicin-induced acute pain with the same potency. In complete Freund's adjuvant (CFA)-induced chronic inflammatory pain, oral administration of either compound blocked thermal hyperalgesia with similar potency. Furthermore, intraplantar or intrathecal administration of A-784168 blocked CFA-induced thermal hyperalgesia, suggesting that both peripheral and CNS TRPV1 receptors may play a role in inflammatory thermal hyperalgesia. The effects of the two TRPV1 antagonists were further assessed in models presumably mediated by central sensitization, including CFA- and capsaicin-induced mechanical allodynia and osteoarthritic pain. In these models, the potency of the two compounds was similar after intrathecal administration. However, when administered orally, A-784168, with good CNS penetration, was much more potent than A-795614. Together, these results demonstrate that TRPV1 receptors in the CNS play an important role in pain mediated by central sensitization. In addition, these results demonstrate that significant CNS penetration is necessary for a TRPV1 antagonist to produce broad-spectrum analgesia.

Comparison of antinociceptive actions of standard analgesics in attenuating capsaicin and nerve-injury-induced mechanical hypersensitivity

Intradermal capsaicin injection produces immediate spontaneous pain behaviors, and a secondary mechanical hypersensitivity (SMH) that is employed in the clinic as a model potentially predictive of human neuropathic pain. Presently, we have characterized capsaicin-induced SMH in rats, and compared pharmacological actions of standard analgesics in this and two nerve injury models, the L5/L6 spinal nerve ligation (SNL) and sciatic nerve chronic constriction injury (CCI) models. Intraplantar capsaicin produced dose-related SMH (enhanced paw withdrawal response to von Frey monofilament stimulation at an area away from injection site) that lasted for over 4 h. While pretreatment with a potent selective transient receptor potential vanilloid receptor-1 (TRPV1) antagonist A-425619 (1-isoquinolin-5-yl-3-(4-trifluoromethyl-benzyl)-urea) prevented development of acute nocifensive (flinching) behavior immediately following capsaicin injection (ED(50)=4.9 mg/kg), the compound failed to attenuate the SMH when administered 2 h following capsaicin (10 microg/10 microl). Additional standard analgesics were also tested 3 h following intraplantar capsaicin in the SMH model. Comparison of their potencies in attenuating mechanical hypersensitivity in capsaicin, SNL and CCI models revealed similar ED(50)s for morphine (2.3 mg/kg, 1.6 mg/kg and 3.2 mg/kg, respectively), gabapentin (33.1 mg/kg, 33.9 mg/kg and 26.3 mg/kg, respectively) and lamotrigine (9.1 mg/kg, 8.9 mg/kg and 15.5 mg/kg, respectively). Duloxetine produced 50-65% effect at the highest tested dose (50 mg/kg), whereas the highest tested doses of morphine (10 mg/kg), gabapentin (85.5 mg/kg) and lamotrigine (30 mg/kg) all produced >70% efficacy in capsaicin SMH, SNL and CCI models. In contrast, celecoxib and ibuprofen showed weak effects in all three models. All standard analgesics generally had weak efficacy in attenuating capsaicin-induced immediate acute flinching behavior when administered before capsaicin. These results provide further support to the suggestions that distinct pharmacological mechanisms underlie capsaicin-induced acute nocifensive and SMH behaviors, and certain neuronal mechanisms underlying neuropathic pain states are also contributory to capsaicin-induced SMH.