Search

We study the semiparametric estimation of the conditional mode of a random vector that has a continuous conditional joint density with a well-defined global mode. A novel full-system estimator is proposed and its asymptotic properties are studied. We specifically consider the estimation of vector autoregressive conditional mode models and of systems of linear simultaneous equations defined by mode restrictions. The proposed estimator is easy to implement and simulations suggest that it is reasonably behaved in finite samples. An empirical example illustrates the application of the proposed methods, including its use to obtain multistep forecasts and to construct impulse response functions. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Although the diagnosis of inherited ataxias is ultimately genetic, this usually means an extensive and expensive process. This justifies the search for distinct clinical signs that may potentially help orient molecular diagnosis. METHODS: We explored the vestibulo-ocular reflex (VOR) with the video Head Impulse Test in patients diagnosed with spinocerebellar ataxia (SCA) type 3 (n = 15), type 1 (n = 4) and type 2 (n = 4), Friedreich's ataxia (FA) (n = 9) and healthy controls (n = 40). We estimated the latency, regression (VORr) and instantaneous VOR gain at 40, 60 and 80 ms (VOR40, VOR60 and VOR80), and determined the latency, peak-velocity and occurrence rate of catch-up saccades triggered with head-impulses. RESULTS: VOR latency was higher in FA (p < 0.001) and SCA3 (p = 0.02) as compared to controls, discriminating FA from other ataxic patients with an overall diagnostic accuracy of 88%. VORr, VOR40 and VOR60 were significantly lower in FA and SCA3 (p < 0.01). VOR80 was only significantly lower than controls in SCA3 (p < 0.01), discriminating these from other ataxic patients with an overall diagnostic accuracy of 78%. Covert saccades were only triggered in SCA3 but with low occurrence rate and peak velocity (11.1±28.5% and 77.50±15.30°/s) whereas overt saccades were present in all groups. VORr gain showed a negative correlation with disease severity evaluated with SARA (Spearman r = -0.46, p = 0.01). CONCLUSIONS: vHIT provides phenotypic information that differentiates these autosomal ataxias and can serve as a strategy to orient genetic diagnosis. A correlation between VOR and SARA raises the possibility of using VOR gain as a neurophysiologic biomarker for disease severity. [ABSTRACT FROM AUTHOR]

Background: Optokinetic nystagmus (OKN) was studied in an immersive virtual reality (VR) environment with both typical optokinetic stimulation (OKs) wherein the head-tracking is active (similar to be sitting in front of a rotating drum) or a unique stimulus (VR-OKs) wherein the head-tracking is turned off, so head movements do not update the visual image (which moves with the head)., Objective: To study both the perception of the stimulus velocity and eye movements while subjects rotated their head from side to side and the visual scene was either a typical OKs or VR-OKs., Methods: 9 healthy participants (aged 23 ± 2.4 y/o) had head and eye movements recorded under typical OKs and VR-OKS while smoothly rotating their head horizontally from side to side. Stimulation was delivered using a virtual reality setup on top of an eye movements recording system., Results: Under VR-OKs participants perceived faster stimulus velocity when the head and stimulus had the same direction as compared to the head and stimulus in opposite directions. When the head turned in the same direction as the stimulus, there were fewer fast phase eye movements than when it rotated counter to stimulus motion direction. Conversely, with typical OKs, participants perceived faster stimulus velocity when the head and stimulus had opposite directions as compared to the head and stimulus having the same direction., Conclusions: The seemingly paradoxical results in which slower stimulus velocity is perceived in tandem with stronger nystagmus can be explained by the simultaneous activation of the Vestibulo-Ocular Reflex and OKN in accordance with the various visual and vestibular stimuli., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Objective: Although the diagnosis of inherited ataxias is ultimately genetic, this usually means an extensive and expensive process. This justifies the search for distinct clinical signs that may potentially help orient molecular diagnosis., Methods: We explored the vestibulo-ocular reflex (VOR) with the video Head Impulse Test in patients diagnosed with spinocerebellar ataxia (SCA) type 3 (n = 15), type 1 (n = 4) and type 2 (n = 4), Friedreich's ataxia (FA) (n = 9) and healthy controls (n = 40). We estimated the latency, regression (VORr) and instantaneous VOR gain at 40, 60 and 80 ms (VOR40, VOR60 and VOR80), and determined the latency, peak-velocity and occurrence rate of catch-up saccades triggered with head-impulses., Results: VOR latency was higher in FA (p < 0.001) and SCA3 (p = 0.02) as compared to controls, discriminating FA from other ataxic patients with an overall diagnostic accuracy of 88%. VORr, VOR40 and VOR60 were significantly lower in FA and SCA3 (p < 0.01). VOR80 was only significantly lower than controls in SCA3 (p < 0.01), discriminating these from other ataxic patients with an overall diagnostic accuracy of 78%. Covert saccades were only triggered in SCA3 but with low occurrence rate and peak velocity (11.1 ± 28.5% and 77.50 ± 15.30°/s) whereas overt saccades were present in all groups. VORr gain showed a negative correlation with disease severity evaluated with SARA (Spearman r = -0.46, p = 0.01)., Conclusions: vHIT provides phenotypic information that differentiates these autosomal ataxias and can serve as a strategy to orient genetic diagnosis. A correlation between VOR and SARA raises the possibility of using VOR gain as a neurophysiologic biomarker for disease severity.

Face transplantation (FT) is fraught with complications parallel to solid organ transplantation (SOT). As such, donor-related cytomegalovirus (CMV) transmission remains one of the most commonly feared viruses associated with FT. With this in mind, a review of the literature seemed justified, knowing that two of the first four face transplant recipients acquired CMV donor-related viral infection. Although the risk of CMV transmission is acceptable in the setting of SOT, the scenario for those composite tissue allotransplantation (CTA) patients, who are often young and healthy, may be different. Experiences from France and Cleveland have both confirmed suboptimal events related to CMV transmission following transplantation. Therefore, using the information provided here, it is imperative that all FT teams remain aware of these potential risks. Furthermore, all patients pursuing facial CTA should be fully informed as to the risks of donor-related CMV transmission, understand the importance of prophylaxis, and be aware of alternative therapies required to prevent symptomatic disease., (Copyright © 2011. Published by Elsevier Inc.)

Numerous achievements have been made encompassing a wide array of composite tissue allograft (CTA) subtypes. We sought to develop a simple, reproducible CTA classification system for the purpose of comparing clinical investigation. Each CTA subtype differs in relative complexity and can therefore be theoretically classified based on its unique combination of multiple factors. Eight complexity factors (CFs) are hypothesized: anatomic detail, psychological obstacles, rejection risk, required rehabilitation, relative antigenicity, functionality/cosmesis, skin ratio, and salvageability. A distribution of total complexity scores, ranging from 8 to 24, is classified into 3 ordered categories representing varying degrees of complexity. In conclusion, we have created a new classification system so that ongoing research and future data may be compared in a type-specific fashion.

Objective: We report our experience over the past 12 years with recreational diving-related inner ear decompression sickness (IEDCS)., Study Design: Retrospective, consecutive case series., Methods: Twenty-four divers, representing 29 cases of IEDCS, are presented with regard to evaluation, treatment, and follow-up., Results: These 29 cases represent 26% of the severe decompression sickness (DCS) cases treated in that period. The patient group includes 22 divers who had a single event of IEDCS, one diver who had two events, and one with five repeated episodes. The cause of injury in 23 cases (79%) was violation of the decompression schedule. The mean time from surfacing to appearance of symptoms was 47 +/- 65 minutes. In 83%, symptoms appeared within 1 hour of ascent, in 97% within 2 hours, and in only one diver after 5.5 hours. Ten divers (34%) had pure vestibular involvement, 4 (14%) had cochlear insult alone, and 15 (52%) had combined vestibulo-cochlear injury. Except for one patient who had central as well as peripheral vestibulo-cochlear DCS, all the remaining patients had end organ involvement only, as demonstrated by physical examination and laboratory test results. Fifteen (52%) had isolated IEDCS, whereas 14 had additional symptoms of DCS. Twenty-six cases were treated by hyperbaric oxygenation with supplementary daily hyperbaric sessions. Of the 25 cases with vestibular injury and the 19 with cochlear damage, only 7 (28%) and 6 (32%), respectively, made a full recovery, whereas the others remained with residual damage. Of the 17 treated within 6 hours of symptom appearance, 9 (53%) were cured, compared with one of the 9 treated later (P <.05)., Conclusions: IEDCS related to compressed-air recreational diving is more common than previously thought, and might occur even when no decompression schedule violation took place. Prompt diagnosis leading to the early commencement of hyperbaric oxygen recompression therapy is the key to complete recovery of cochlear and vestibular function.

On 27 May 1999, a big brown bat (Eptesicus fuscus) was discovered on an island exhibit at the Denver Zoo that contained a troop of 15 hooded capuchin monkeys (Cebus apella cay). The monkeys were attacking the bat when it was discovered. The bat was collected and humanely euthanatized without direct handling and submitted to the Colorado Department of Public Health and Environment Virology Laboratory for rabies evaluation. The monkeys had not been vaccinated against rabies virus. The next day, the laboratory confirmed that the bat was positive for rabies. The recommendations from the Colorado Department of Public Health and Environment and the Centers for Disease Control and Prevention were to euthanatize the monkeys or quarantine them and comply with the human nonvaccinated postexposure protocol. A 1-ml dose of a killed rabies vaccine was administered i.m. in the hip on each of days 2, 7, 12, 19, and 33 postexposure, and a single dose of human rabies immune globulin was administered i.m. 5 days postexposure. Blood was collected under anesthesia in order to evaluate the immune response after rabies vaccination from six monkeys 5 days postexposure, six monkeys 19 days postexposure (five of the six monkeys were the same monkeys bled 5 days postexposure), 15 monkeys 67 days postexposure, and 13 monkeys approximately 1 yr postexposure. All of the monkeys developed and maintained levels of rabies virus neutralizing antibody above 0.05 IU/ml by 67 days postexposure. Although a serologic titer of 0.05 IU/ml indicates an adequate human response after rabies vaccination, no similar information is available for nonhuman primates. To date, none of the monkeys has succumbed to rabies.

The telomeric repeat amplification protocol (TRAP) assay was used to measure telomerase activity in radiation-induced mouse myeloid leukemic (ML) cells and in several populations of normal cells. A detectable level of telomerase activity was found in normal hematopoietic tissues, i.e., bone marrow (BM) cells, day 9 colony-forming unit spleen (CFU-S) colonies, peripheral blood (PB) lymphocytes, and spleen. The level of telomerase activity in normal BM cells was used as a background level. Nine of the 12 cases of ML had higher levels of activity than that of the normal BM cells and therefore they were scored as ML with positive telomerase. The other three cases were considered as ML with negative telomerase because the levels of the enzyme were equivalent to that of normal BM cells. The data indicate that cellular differentiation may suppress telomerase activity in mouse ML cells. In summary, the results suggest that the CBA/Ca mouse model should be a useful animal system for future studies on the assessment of telomerase activity in both malignant and normal hematopoietic cells., (Copyright 2001 Academic Press.)