Impedance vector distribution by sex, race, body mass index, and age in the United States: standard reference intervals as bivariate Z scores

Bioelectrical impedance measurements were collected in the Third National Health and Nutrition Examination Survey (NHANES III), but their results have not been published. In the NHANES III population, resistance (R) and reactance (Xc) values at 50-kHz frequency were obtained with a Valhalla Scientific meter (model 1990B; San Diego, CA, USA). The RXc graph method was used to identify bivariate pattern distributions of mean vectors (95% confidence ellipses by sex, race, age, and body mass index [BMI]), and individual impedance vectors (50%, 75%, and 95% tolerance ellipses). Data from 10 222 adults (5261 men and 4961 women) formed 90 four-way classification groups, with two sexes, three races or ethnicities (non-Hispanic white, non-Hispanic black, Mexican American), five age classes (20-29, 30-39, 40-49, 50-59, and 60-69 y), and three BMI classes (19-24.9, 25-29.9, and 30-34.9 kg/m(2)). Sex, race or ethnicity, BMI and age, in decreasing order, influenced the vector distribution pattern. Mean vectors in women were significantly longer than those in men. Within each sex, the mean vector of non-Hispanic white subjects was shorter and with a smaller phase angle than that of corresponding BMIs from the two other race/ethnic populations. Tolerance ellipses were calculated from sex- and race-specific reference populations 20 to 69 y old and 19 < or = BMI < 30 kg/m(2) (8022 subjects, 4226 men and 3796 women). After transformation of impedance vector components into bivariate Z scores (standardized deviates, as differences from the mean divided by the standard deviation of the reference population), we constructed one standard, reference, RXc-score graph (50%, 75%, and 95% tolerance ellipses) that can be used with any analyzer in any population. The pattern of impedance vector distribution and reference bivariate intervals for the individual impedance vector are presented for comparative studies (free software at E-mail: apiccoli@unipd.it).     

Electric to acoustic pitch matching: a possible way to improve individual cochlear implant fitting

Poor pitch resolution has been shown to have negative implications for speech and music perception in implanted patients. Surprisingly, works on the subject have not focused much on the impact that the non-correspondence between frequencies allocated to electrodes and perceived frequencies could have on speech and music perception. The aim of the present study is to investigate the correlation between pitch mismatch and speech performance with the implant, and to ascertain the effects of mismatch correction through a mapping function making a personalized frequency reallocation possible. We studied ten postlingually deaf adult patients with detectable bilateral residual hearing, implanted in our Clinic with Cochlear^® Nucleus devices. In each test session, we asked the patients to find the best match between the pitch elicited by the residual ipsilateral and contralateral pure tones and the pitch elicited by stimulation of electrodes. We also assessed patients’ vowel and consonant recognition performance. Finally, in the only implanted patient in our clinic who had bilateral residual hearing and used a Digisonic DX10/C^® device, which makes manual electrode-by-electrode frequency reallocation possible, we modified electrode-assigned frequency ranges on the basis of the pitch matching test results. We found that in none of the studied patients, the electric-to-acoustic pitch matching corresponds to the theoretical assignment pattern. A very strong correlation was detected between the electric-to-acoustic pitch mismatch and patient’s speech performance. In the Digisonic^® patient, a remarkable improvement in all phoneme recognition scores was obtained 1 month after frequency reallocation. In the light of our results, we propose to assess, whenever possible, any frequency-to-electrode mismatch in all implanted patients, and correct it through mapping programs allowing manual frequency reallocation for the pitch-matched electrodes, and automated allocation of the non-tested electrodes. Cochlear implantation should therefore be proposed when residuals for all frequencies are still present, at least in one ear, so as to allow optimal alignment between allocated and subjectively perceived frequencies.     

Predicting in vitro tissue culture growth for cytogenetic evaluation of stillborn fetuses

A prospective study was undertaken of 131 perinatal deaths to determine whether gestational age, body weight, maceration degree and autopsy interval influenced successful in vitro tissue culture for cytogenetic evaluation. Perinatal populations were categorized as neonatal death (NND), fresh stillbirth (FSB), or graded as macerated stillbirth (MAC-0, MAC-1, MAC-2, MAC-3). Metaphase production by at least 15 cells separated 'growth' from 'no growth' categories after sampling liver, kidney and spleen. Body weight and degree of maceration were predictive of successful 'growth', while gestational age and autopsy interval were not. Body weight was significant in separating 'growth' from 'no growth' in NND (P = 0.05), FSB, MAC-0 and MAC-1 (P = 0.01). Growth probabilities were 0.78 (NND), 0.57 (FSB), 0.49 (MAC-0), 0.38 (MAC-1) and zero for MAC-2 and MAC-3. We conclude that (a) tissues from MAC-2 and MAC-3 fetuses do not grow and thus need not be sampled at autopsy, (b) maceration degree and body weight can be used to predict the growth probability in the other categories, (c) tissue samples can be taken during daylight hours, since autopsy interval does not influence successful growth provided the fetus is refrigerated at 4 degrees C, (d) all of the above conclusions have cost-efficiency implications for cytogenetic laboratories.     

Quality of life and disability assessment in neuropathy: a multicentre study

Neuropathy can severely affect patients' quality of life (QoL), causing disability and decreased motor efficiency while modifying their perception of the external environment. We performed a large, multi-perspective, and multi-measurement assessment using validated clinical measurements of disability and QoL. With regard to general disability, more than 10% of patients needed assistance to walk. With regard to arm disability, about 10% of patients had severe disability defined as impairment in carrying out simple tasks. General disability was similar both in polyneuropathic and multi-neuropathic groups, but arm disability appeared more severe in multi-neuropathic patients. QoL profiles were highly deteriorated in our sample with respect to the Italian normative sample. All age brackets were highly impaired except for older patients for whom the QoL picture was only mildly impaired with respect to Italian norms. We believe that our study provides reliable data on QoL in patients with neuropathies and that it may represent a quantitative step forward in understanding the disability of patients with neuropathy.     

A novel method for subarachnoid drug delivery in the medullary region of rats

This study describes a novel method for direct subarachnoid drug delivery to the medullary dorsal horn region of rats, without introducing a catheter. The reliability of the method was demonstrated by a pharmacological validation; that is, morphine administration to the medullary region blocked the nociceptive response to formalin injected in the temporomandibular joint (TMJ) region, an effect that was prevented by co-administration of naloxone. The method proposed offers many advantages over the existing methods for medullary drug delivery with catheter implantation. It is easy to be employed, it does not induce any sign of motor impairment, and it does not require the neck surgery performed to implant a catheter in the medullary dorsal horn region. Therefore, it is a useful method for subarachnoid drug delivery in behavioral trigeminal pain studies, particularly when nociceptive behavioral measures that require normal neck muscle activity to occur, such as head withdraw or head flinch, are evaluated.