Dissociated Representation of Binaural Cues in Single-Sided Deafness: Implications for Cochlear Implantation.

Congenital single-sided deafness (SSD) leads to an aural preference syndrome that is characterized by overrepresentation of the hearing ear in the auditory system. Cochlear implantation (CI) of the deaf ear is an effective treatment for SSD. However, the newly introduced auditory input in congenital SSD often does not reach expectations in late-implanted CI recipients with respect to binaural hearing and speech perception. In a previous study, a reduction of interaural time difference (ITD) sensitivity has been shown in unilaterally congenitally deaf cats (uCDC). In the present study, we focused on the interaural level difference (ILD) processing in the primary auditory cortex. The uCDC group was compared with hearing cats (HC) and bilaterally congenitally deaf cats (CDC). The ILD representation was reorganized, replacing the preference for the contralateral ear with a preference for the hearing ear, regardless of the cortical hemisphere. In accordance with the previous study, uCDCs were less sensitive to interaural time differences than HCs, resulting in unmodulated ITD responses, thus lacking directional information. Such incongruent ITDs and ILDs cannot be integrated for binaural sound source localization. In normal hearing the predominant effect of each ear is excitation of auditory cortex in the contralateral cortical hemisphere and inhibition in the ipsilateral hemisphere. In SSD, however, auditory pathways reorganized such that the hearing ear produced greater excitation in both cortical hemispheres and the deaf ear produced weaker excitation and preserved inhibition in both cortical hemispheres.Significance statement Congenital single-sided deafness is a clinically relevant form of hearing loss. We studied this phenomenon in a unique animal model with congenital deafness of one ear and normal hearing of the other ear with electrical stimulation on both ears. Differential effects of single-sided deafness on interaural time and level difference sensitivity were observed, consistent with the aural preference syndrome. The influence of the previously hearing ear became dominant and the deaf ear mildly suppressive in the majority of units in both hemispheres, resulting in an inconsistent representation of binaural cues. These changes in neuronal representation of the two ears explain why late restoration with cochlear implants in single-sided deafness often results in insufficient benefit of the previously deaf ear.

Incidental fallopian tube mesothelioma diagnosed at time of elective bilateral salpingectomy for sterilisation: A case report.

•Incidental finding of a fallopian tube lesion at the time of bilateral salpingectomy•Histopathological appearance not consistent with mucinous or serous carcinoma, appearance of mesothelioma•Very rare known primary neoplasm of tubal mesothelium, favours an indolent course•Recommendation for prophylactic hysterectomy and bilateral oophorectomy•If nil further spread, generally nil further treatment is required.

The impact of clozapine on hospital use: a systematic review and meta-analysis.

OBJECTIVE: The objective of this study was to perform a systematic review and meta-analysis of studies reporting the impact of clozapine on hospital use in people with a psychotic illness. METHOD: PubMed, EMBASE, PsycINFO and the Cochrane Schizophrenia Group Trials Register were systematically searched from inception to 12 October 2016. We included all trials and observational studies, except case reports. RESULTS: Thirty-seven studies were included. Clozapine significantly reduced the proportion of people hospitalised compared to control medicines (RR = 0.74; 95% CI: 0.69-0.80, P < 0.001, 22 studies, n = 44 718). There were significantly fewer bed days after clozapine treatment compared to before clozapine treatment in both controlled (MD = -34.41 days; 95% CI: -68.22 to -0.60 days, P = 0.046, n = 162) and uncontrolled studies (MD = -52.86 days; 95% CI: -79.86 days to -25.86 days, P < 0.001, n = 2917). Clozapine and control medicines had a similar time to rehospitalisation (-19.90 days; 95% CI: -62.42 to 22.63 days, P = 0.36). CONCLUSION: Clozapine treatment reduced the number of people hospitalised and the number of bed days after treatment compared with before treatment. Clozapine has the potential to reduce acute hospital use among people with treatment refractory schizophrenia.

Consideration for safe and effective gynaecological laparoscopy in the obese patient.

BACKGROUND: The number of obese and morbidly obese patients within the developed world is dramatically increasing within the last 20 years. Apart from demographical changes, obese patients are especially prone to have oestrogen-dependent morbidities and neoplasias, of which laparoscopic treatment should be the standard of care. The increasing number of patients with BMI >40 is concerning, making it necessary to summarise considerations for safe and effective Gynaecological Laparoscopic Surgery. CONSIDERATIONS: The sequel to successful laparoscopic surgery in obese patients comprises an interdisciplinary appreciation of laparoscopy. Preoperatively, anaesthetics and medical review are suggested to optimise treatment of comorbidities (i.e. infections and blood sugar levels). Positioning of the patient should consider anti-slip options and pannus fixation to ease laparoscopic access and decrease pressure to the chest. There is no standard port placement in obese patients and landmarks have to be the bony structures of the pelvis and ribs. Retraction of the bowel is essential and mobilisation of the sigmoid with fan retractors or endoloops can accomplish adequate vision. 30° scopes can be considered for vision "around the obstacle". An experienced assistant with anticipation of surgical steps is favourable for successful surgery completion. Intra-operatively, good surgical techniques are essential. Vessel sealing systems reduce the need for instrument changes and may be helpful in following visualised tissue planes. A transvaginal vault closure may be advantageous compared to laparoscopic closure and Endostiches may be preferred to close the fascia of large trocar sites under vision.

Response properties of local field potentials and multiunit activity in the mouse visual cortex.

Extracellular local field potentials (LFPs) and multiunit activity (MUA) reflect the spatially integrated activity of multiple neurons in a given cortical structure. In the cat and primate visual cortices, these signals exhibit selectivity for visual stimulus features, such as orientation, direction of motion or spatial frequency. In the mouse visual cortex, a model which has been increasingly used in visual neuroscience, the visual stimulus selectivity of population signals has not been examined in detail. We recorded LFPs and MUA using multielectrode arrays and two derived measures, the high-pass filtered continuous MUA and the bipolar first spatial derivative of the LFP, in the visual cortex of isoflurane-anesthetized C57Bl/6 mice. We analyzed the onset latency and characterized the receptive fields in addition to the direction, orientation, and spatial and temporal frequency preferences of these signals. Population signals exhibited onset latencies as short as ∼30ms and possessed receptive fields as large as ∼38° with MUA receptive fields smaller than those of LFPs. All four population signals exhibited similar spatial frequency preferences (∼0.1 cycles per degree) and temporal frequency preferences (∼1 cycle per second). However, for all population signals, spatial and frequency tunings were broad and orientation and direction of motion preferences were absent. The characterization of the visual stimulus selectivity of LFPs and MUA in the mouse visual cortex should provide information regarding their usability in characterizing stimulus properties and disclose possible limitations.

Broadband spectroscopy of dynamic impedances with short chirp pulses.

An impedance spectrum of dynamic systems is time dependent. Fast impedance changes take place, for example, in high throughput microfluidic devices and in operating cardiovascular systems. Measurements must be as short as possible to avoid significant impedance changes during the spectrum analysis, and as long as possible for enlarging the excitation energy and obtaining a better signal-to-noise ratio (SNR). The authors propose to use specific short chirp pulses for excitation. Thanks to the specific properties of the chirp function, it is possible to meet the needs for a spectrum bandwidth, measurement time and SNR so that the most accurate impedance spectrogram can be obtained. The chirp wave excitation can include thousands of cycles when the impedance changes slowly, but in the case of very high speed changes it can be shorter than a single cycle, preserving the same excitation bandwidth. For example, a 100 kHz bandwidth can be covered by the chirp pulse with durations from 10 µs to 1 s; only its excitation energy differs also 10(5) times. After discussing theoretical short chirp properties in detail, the authors show how to generate short chirps in the microsecond range with a bandwidth up to a few MHz by using digital synthesis architectures developed inside a low-cost standard field programmable gate array.

Broadband excitation for short-time impedance spectroscopy.

Frequency domain impedance measurements are still the common approach in assessing passive electrical properties of cells and tissues. However, due to the time requirements for sweeping over a frequency range for performing spectroscopy, they are not suited for recovering fast impedance changes of biological objects. The use of broad bandwidth excitation and monitoring the response as a function of time will greatly reduce the measurement time. The widespread usage of a square wave excitation is simple but not always the best choice. Here we consider different waveforms for excitation and discuss not only the advantages but also their limitations. Measurements in a miniaturized chamber where frequency and time domain measurements are compared show the suitability of different waveforms as excitation signals for the measurements of bio-impedance. The chirp excitation has been found to be most promising in terms of frequency range, signal-to-noise ratio and crest factor.

Routine computerized tomography scanning, groin ultrasound with or without fine needle aspiration cytology in the surgical management of primary squamous cell carcinoma of the vulva.

We set out to study whether computerized tomography (CT) scanning of the vulva and the groin and groin ultrasound scanning (USS) alone or with fine needle aspiration cytology (FNAC) (USS/FNAC) influenced or could influence the surgical management of primary squamous cell carcinoma of the vulva (SCCaV). Forty-four patients underwent surgery for primary SCCaV following radiologic imaging by one or more modalities. Patient details included the clinical assessment of the carcinoma, radiologic findings, the operation performed, and whether the decision regarding the type and extent of surgery for the vulval carcinoma and, in particular, for the groin node dissection was or could be influenced by the radiologic findings. The age range was 38-87 years, with a median of 74 years. A total of 75 groin dissections were performed. Twenty-five of the 44 patients (56.8%) did not have groin node metastasis, 14 had unilateral metastasis (31.8%), and 5 (11.4%) had bilateral metastasis. All cases with histologically proven nodal status were analyzed to compare the preoperative imaging status with the histology. The calculated sensitivity, specificity, negative predictive value, and positive predictive value for CT were 58%, 75%, 75%, and 58%, for USS alone-87%, 69%, 94%, and 48%, and for USS-guided FNAC-80%, 100%, 93%, and 100%, respectively. There was no patient in whom surgical planning for the vulval carcinoma or the groin nodes was or could be altered by the CT findings. The data do not support the routine use of CT scanning in patients with primary SCCaV, either in assessment of the primary vulval carcinoma or in detecting groin nodal metastases. For the groin nodes, USS/FNAC is superior to CT in assessing disease status. In contrast to CT, USS/FNAC may have a useful clinical role in the management of the groin nodes in vulval carcinoma.

A sampling multichannel bioimpedance analyzer for tissue monitoring.

The paper focuses on principles of designing of a multichannel bioimpedance analyzer based on simultaneous multisine measurement. The measurement task arises due to the need to monitor patients during and after heart surgery operation performing MIMO (multiple-input-multiple-output) bioimpedance measurement. Frequencies of the simultaneously applied sinusoidal excitations must be close but simultaneously varied in a larger range (e.g. from 1 kHz up to 10 MHz). The main idea of the proposed approach is that the use of a rather specific signal system (frequencies of sinusoidal excitations are related as integers and sampling frequencies are properly related/adapted to them) makes it possible to separate responses to different excitations from the measured summary signals by means of a quite simple filter and different (under) sampling rates.

Modification of pulse wave signals in electrical bioimpedance analyzers for implantable medical devices.

The problems of application of pulse wave signals in electrical bioimpedance analyzers foreseen for using in implantable medical devices as diagnostical means are discussed in this paper. The main problem arises at measurement of phasor parameters by the aid of rectangular pulse wave signals. The specific measurement errors appear due to presence of higher harmonics in the spectra of pulse waveforms. These errors are discussed in two cases, in the case of full cycle rectangular waveform, and in the case of using the shortened pulses introduced specially for reduction of errors.

Personal preferences of obstetricians towards childbirth.

Our objective was to determine obstetricians' personal choices in relation to modes of delivery and long-term outcomes. A structured confidential survey was mailed out to all Australian and New Zealand Fellows, Members, and Australian Trainees with The Australian and New Zealand Journal of Obstetrics and Gynaecology November 1999 edition. The response rate overall was 26% (478). Eleven per cent (54) chose to have an elective Caesarean section (ECS) in the absence of any clinical indication. The most common reason for this was fear of faecal and urinary incontinence (82%). Two-thirds (318) were agreeable to patients requesting an ECS in this same setting. Twenty-six per cent said they would choose ECS if the estimated fetal weight (EFW) was > 4000 g which more than doubled to 55% (261) if EFW was > 4500 g. Ventouse delivery was the most popular method of assisted rotational delivery at 45% (214) followed closely by Keilland's forceps at 40% (189). Caesarean section (CS) was chosen by only 14% (65) in this scenario. ECS was the preferred method for breech delivery at 38% (181) followed by trial of breech delivery at 23% (109). Thirty-two per cent (154) of respondents would attempt external cephalic version prior to deciding mode of delivery. Respondents felt the most important factors for postnatal incontinence included: antenatal incontinence (64%), length of second stage > one hour (50%), forceps delivery (46%), and EFW > 4000 g at term (44%).

A comparison of rural and urban ambulance crashes.

Ambulance crashes are a significant safety issue both to the EMTs and to patients transported in the vehicle. Safety issues are dependent on the environment and may be different in rural and urban settings. Ambulance crashes reported to the State EMS bureau during the years of 1993 to 1997 were evaluated. Counties with >250,000 population were considered urban. State population was 2 million urban and 2.8 million rural. Two investigators determined first if the crash was urban or rural. Outcome information was extracted on the degree of injury, citations given, and information on the ambulance and other vehicle condition. In addition, independent variables of weekend versus weekday, day versus night, posted speed, weather, road condition (wet versus dry), intersections, and use of seat belts were extracted. Results were compared using a 2-tailed Chi-square or Fisher's exact with significance at P <.05. Relative risks and 95% confidence intervals were calculated for each variable. There were a total of 183 Ambulance crashes, 115 urban (19/million pop/yr), and 68 rural (8/million pop/yr). Significantly lower percentage of injury crashes occurred in the urban setting (OR = 0. 49, 95% CI = 0.24 to 0.98) with fewer of these considered "severe" (OR = 0.0, 95% CI = 0.0 to 0.73). Citations were more likely to be issued to the urban ambulance driver (OR = 4.95, 95% CI = 1.09 to 45. 70) and the other urban vehicle driver (OR = 3.65, 95% CI = 1.37 to 11.31). However, the urban ambulance was less likely to be damaged (OR = 0.24, 95% CI = 0.10 to 0.55), disabled (OR = 0.41, 95% CI = 0. 20 to 0.84), or towed (OR = 0.40, 95% CI = 0.20 to 0.83). In the urban setting fewer vehicles were traveling in areas with posted speeds >54 mph (OR = 0.24, 95% CI = 0.06 to 0.78) and nonrestrained people were less likely to be injured (OR = 0.28, 95% CI = 0.06 to 1. 25). For injured persons there was no difference in independent variables in the urban versus rural settings. Although the rate of ambulance injuries was greater in the urban environment, the severity of the injuries was worse in the rural environments where crashes occurred at higher posted speeds. In the rural setting nonrestrained passengers were more likely to be injured.

A practical method for measuring macular pigment optical density.

PURPOSE: Increasing evidence indicates that the macular pigments (MP) protect the central retina and may retard macular disease. For that reason, a practical method for measuring MP that does not require elaborate optics and can be applied to diverse populations by operators with a modest amount of experience was developed and validated. METHODS: A small tabletop device based on light-emitting diodes (LEDs) as the light source with electronic controls was constructed. Macular pigment was measured with the tabletop device with a 1 degrees test stimulus at 460 nm using heterochromatic flicker photometry, and the results were compared with measurements using a traditional three-channel Maxwellian view system with a xenon-arc source. RESULTS: Macular pigment density of 30 subjects (age range, 16-60 years) was measured with both stimulus systems. Macular pigment measured with the LED tabletop device in free view was highly correlated with MP measured in Maxwellian view (y = -0.03 + 1.06x, r = +0.95). The average absolute difference between the two techniques was 0.04 (SD, 0.03). The new technique was not significantly affected by variations in lens optical density, pupil size, or small head movements. CONCLUSIONS: Psychophysical measurement of MP provides a unique opportunity to make repeated noninvasive assessment of the concentration of a protective nutrient in the retina. The availability of this new device should make this measurement technology accessible to a wide variety of investigators for application to diverse populations.

Dietary manipulation of plasma carotenoid concentrations of squirrel monkeys (Saimiri sciureus).

Primate retinas accumulate the dihydroxy xanthophylls, lutein and zeaxanthin, from the diet via the plasma. Control of plasma concentrations of these carotenoids may be useful for prevention of retinal disease by manipulating carotenoid content of the retina. We have measured the plasma response of male squirrel monkeys to changes in the carotenoid content of a nonpurified diet. We have also supplemented the diet with zeaxanthin and beta-carotene. Plasma responses to dietary changes were rapid. Within one week, most of the change in plasma concentrations had already occurred. Within two weeks of increasing zeaxanthin intake, plasma zeaxanthin concentrations were at a new, relatively stable level. beta-carotene concentrations in the plasma were low while the monkeys were consuming a standard laboratory diet, and were only slightly increased by supplementation. Plasma lutein concentrations were unaffected by zeaxanthin supplementation. Our results suggest that it should be possible to manipulate plasma concentrations of each of the retinal carotenoids with little impact on the plasma concentrations of the other. This will facilitate exploration of the rates of accumulation of lutein and zeaxanthin in the retina, as well as exploration of the possibility of bioconversion from one xanthophyll to another.

Ethics and health in a changing world.

Seven advisers from a wide variety of health-related professions met with some 30 staff at WHO to discuss ethical issues currently arising in health and international cooperation. Far-reaching questions of responsibility and legitimacy were raised. The following observations are adapted from the final report on the meeting.

Sudden death in a young athlete due to an anomalous commissural origin of the left coronary artery, and focal intimal proliferation of aortic valve leaflet at the adjacent commissure.

Sudden death occurred in a 15-year-old female athlete with an unusual anomalous left coronary artery. The left coronary artery origin was at (below) the commissure between the left and noncoronary aortic valve cusps. The ostium was slitlike and had an aortic ridge superiorly. In addition, there was an anomalous moundlike intimal proliferation of the noncoronary leaflet adjacent to the left coronary ostium that may have been an additional factor contributing to obstruction of coronary blood flow during diastole.

Aminoglycoside-induced increase of intracellular calcium in LLC-PK1 cells due to an artifact caused by trypsin and EDTA.

Dietary calcium supplements attenuate experimental aminoglycoside nephrotoxicity. In cultured renal tubular cells, intracellular calcium levels have been reported to rise with aminoglycoside addition to the culture medium. In experiments designed to verify the in vitro influence of calcium on cultured kidney cells, we detected an unexpected artifact. When we resuspended cultured LLC-PK1 cells with trypsin and EDTA to measure intracellular calcium levels, our results correlated well with previously reported values. However, we saw no increase in intracellular calcium levels when we measured them by digital imaging video microscopy unless trypsin-EDTA exposure preceded aminoglycoside exposure. This apparent artifact should be considered in any study of the effects of various agents on intracellular calcium levels.

Needle localization for nonpalpable breast lesions.

Breast cancer will affect approximately one woman in nine, and it is estimated that approximately one-third of the 500,000 new cases of cancer among American women in 1993 will be cancer of the breast. With no current method of prevention available, early detection of breast cancer by regular self and physician performed breast examination in conjunction with screening mammography is emphasized. The rate of breast cancer detection has accelerated due to the ability of mammography to identify nonpalpable breast lesions. From January 1987 to January 1992, 1,323 breast biopsies were performed at Erlanger Medical Center, with 559 of these biopsies performed on 541 patients, utilizing needle localization. Of the 559 biopsies, 92 were positive for malignancy (17%). The mean patient age at detection of malignant lesions was 55.2 years. The most common mammographic abnormality leading to biopsy was an irregular breast tissue matrix (mass or density) with 25/191 (13%) biopsies positive for malignancy. The mammographic abnormality associated with the highest malignancy rate was the presence of calcifications in association with a mass or density 16/56 (29%). The upper outer quadrant (UOQ) was the most common site of biopsy 313/559 (56.0%), and biopsies from this region had the highest incidence of malignancy 67/313 (21%). Eighty-seven of the 92 patients with biopsy-proven malignancy underwent subsequent definitive surgical treatment. Tumor size did not correlate with node negative status, but evidence of microscopic invasion did. Preinvasive (in-situ) lesions were present in 23/92 biopsies (25%). There was no axillary involvement associated with in-situ carcinomas.

Role of gonadal negative feedback on the gonadotrophin responses to gonadotrophin-releasing hormone (GnRH) in ram lambs from two lines of sheep selected for their luteinizing hormone response to GnRH.

Divergent selection has resulted in two lines of lambs (high and low) that have a 5-fold difference in their ability to release luteinizing hormone (LH) in response to 5 micrograms of gonadotrophin-releasing hormone (GnRH). Baseline gonadotrophin concentrations, the gonadotrophin responses to a GnRH challenge and the concentrations of testosterone and oestradiol were compared in lambs which were castrated at birth and intact lambs from both selection lines at 2, 6, 10 and 20 weeks of age. The pattern of LH and follicle-stimulating hormone (FSH) secretion was similar in the two lines, but differed between the intact and the castrated lambs. Basal LH and FSH secretion were significantly higher in the castrates than in the intact lambs from both selection lines. The high-line lambs had significantly higher basal FSH concentrations at all ages tested and significantly higher basal LH concentrations during the early postnatal period. The magnitude of the gonadotrophin responses to GnRH differed significantly between the intact and the castrated lambs within each line, the amount of gonadotrophins secreted by the castrated lambs being significantly greater. The removal of gonadal negative feedback by castration did not alter the between-line difference in either LH or the FSH response to the GnRH challenge. Throughout the experimental period, the concentration of testosterone in the intact lambs was significantly greater than in the castrated lambs in both selection lines, but no significant difference was seen in the concentrations of oestradiol. No significant between-line differences were found in the peripheral concentrations of testosterone or oestradiol in the intact lambs from the two selection lines. Therefore, despite similar amounts of gonadal negative feedback in the selection lines, there were significant between-line differences in basal gonadotrophin concentrations, at 2 and 6 weeks of age, and in the LH and FSH responses to an exogenous GnRH challenge, at all ages tested. Removal of gonadal negative feedback did not affect the magnitude of the between-line difference in the response of the lines to GnRH stimulation. The results indicate that the effects of selection on gonadotrophin secretion are primarily at the level of the hypothalamo-pituitary complex.