Peripheral Hearing Loss and Its Association with Cognition among Ethnic Chinese Older Adults.

INTRODUCTION: Many studies on hearing loss (HL) and cognition are limited by subjective hearing assessments and verbally administered cognition tests, the majority of the document findings in Western populations. This study aimed to assess the association of HL with cognitive impairment among ethnic Chinese Singaporean older adults using visually presented cognitive tests. METHODS: The hearing of community-dwelling older adults was assessed using pure tone audiometry. Cognitive function was assessed using the Computerized Cambridge Cognitive Test Battery (CANTAB). Multiple regression analyses examined the association between hearing and cognitive function, adjusted for age, education, and gender. RESULTS: HL (pure-tone average [PTA] of thresholds at 0.5, 1, 2, and 4 kHz in the better ear, BE4PTA) was associated with reduced performance in delayed matching and multitasking tasks (ß = -0.25, p = 0.019, and ß = 0.02, p = 0.023, respectively). Moderate to severe HL was associated with reduced performance in delayed matching and verbal recall memory tasks (ß = -10.6, p = 0.019, and ß = -0.28, p = 0.042). High-frequency HL was associated with reduced performance in the spatial working memory task (ß = 0.004, p = 0.022). All-frequency HL was associated with reduced performance in spatial working memory and multitasking (ß = 0.01, p = 0.040, and ß = 0.02, p = 0.048). CONCLUSION: Similar to Western populations, HL among tonal language-speaking ethnic Chinese was associated with worse performance in tasks requiring working memory and executive function.

Unusual clinical manifestation and challenging serological interpretation of syphilis: insights from a case report.

BACKGROUND: The clinical manifestations of recent syphilis can be variable, with typical and atypical patterns. Several conditions may cause atypical clinical aspects, including human immunodeficiency virus (HIV) co-infection. Besides the clinical features, co-infections may completely alter syphilis serological tests, causing interpretative difficulties and diagnostic delays. Aim of the work is to describe the difficulties encountered during the diagnostic evaluation of atypical skin manifestations and of the serology for syphilis of an HIV-infected patient who had contracted it several times. CASE PRESENTATION: In 2020, a 52-year old HIV-positive bisexual male patient was admitted to our department with a 4-month history of moderately itchy cutaneous lesions localized at his neck, trunk and arms. In 2013, the patient presented with a classic syphilitic roseola of the trunk and a secondary syphilis was diagnosed, with increased levels of rapid plasma reagin (RPR), Treponema pallidum hemagglutination assay (TPHA), anti-Treponema pallidum IgM and IgG Index. A second episode occurred in 2018, as a primary syphilis with multiple ulcerative lesions of the penis, and increased levels of RPR, IgG and IgM. In 2019, a further episode of secondary syphilis was treated with Doxycycline. In 2020, erythematous and papular lesions with vesicular components and urticarial erythema multiforme (EM)-like lesions were present at the neck, trunk and arms. Serological tests and Nucleic Acid Amplification Test (NAAT) for Treponema Pallidum were performed, as well as a cutaneous biopsy with histological and immunohistochemical evaluation of one lesion. NAAT was negative for T. pallidum. Serological test results were discordant with a new syphilis infection, showing only increased levels of RPR and anti-Treponema IgG. The cutaneous biopsy revealed a non specific histological pattern, while the immunohistochemical evaluation with anti-spirochetal antibodies was mandatory for the diagnosis of recent syphilis, showing clusters of rod-shaped elements, some of which with spiral form, focally present at the epidermis and adnexal structures. CONCLUSIONS: Nowadays, syphilis may present with atypical clinical and serological features. Physicians should be aware of these possible alterations and consider syphilis even in case of uncommon clinical aspect and unclear serological tests. Cutaneous biopsy and immunohistochemical exam may be mandatory for the diagnosis.

Hearing and vision health for people with dementia in residential long term care: Knowledge, attitudes and practice in England, South Korea, India, Greece, Indonesia and Australia.

OBJECTIVES: Up to 90% of people with dementia in long term care (LTC) have hearing and/or vision impairment. Hearing/vision difficulties are frequently under-recognised or incompletely managed. The impacts of hearing/vision impairment include more rapid cognitive decline, behavioural disturbances, reduced quality of life, and greater care burden. This research investigated LTC staff knowledge, attitudes and practice regarding hearing/vision care needs for residents with dementia. METHODS: A survey of staff in LTC facilities in England, South Korea, India, Greece, Indonesia and Australia. Respondents used a five-point scale to indicate agreement or YES/NO response to questions regarding sensory-cognitive care knowledge (what is known); attitudes (what is thought); practice (what is done). RESULTS: Respondents reported high awareness of hearing/vision care needs, although awareness of how to identify hearing/vison difficulties or refer for assessment was low. Most felt that residents were not able to use hearing/vision devices effectively due to poor fit, being poorly tolerated or lost or broken devices. A substantial minority of respondents reported low confidence in supporting use of assistive hearing/vision devices, with lack of training the main reason. Most staff did not undertake routine checking of hearing/vision devices, and it was rare for facilities to have designated staff responsible for sensory needs. Variation among countries was not significant after accounting for staff experience and having received dementia training. CONCLUSIONS: There is a need to improve sensory support for people with dementia in LTC facilities internationally. Practice guidelines and training to enhance sensory-cognitive knowledge, attitudes and practice in professional care teams is called for.

Association between hearing loss and frailty: a systematic review and meta-analysis.

BACKGROUND: Frailty is associated with poor health outcomes in later life. Recent studies suggested that hearing loss may be a potentially modifiable risk factor associated with frailty. METHODS: This systematic review and meta-analysis aimed to investigate the association between hearing loss and frailty in observational studies of adults aged 50 years or over. We included observational studies with participants ≥ 50 years old that have clear descriptions of hearing and frailty measurement methods. Meta-analyses were conducted using measurement of risk and 95 % confidence interval of each individual study. Quality assessment, risk of bias, heterogeneity and sensitivity analyses were also conducted. Our study followed PRISMA guidelines. RESULTS: Our search identified 4508 manuscripts published in English between 1 and 2000 and 9 February 2021. Sixteen articles reported acceptable measurements of both hearing loss and frailty. Two papers were not suitable for meta-analysis. Twelve sets of cross-sectional data involving 12,313 participants, and three sets of longitudinal data involving 3042 participants were used in the meta-analysis. Hearing loss was associated with an 87 % increase in the risk of frailty among cross-sectional studies (risk ratio [RR] 1.87; 95 %CI 1.63-2.13) and 56 % among longitudinal studies (RR 1.56; 95 %CI 1.29-1.88). There was considerable heterogeneity among studies, but their quality rating, sample size or approach used to assess hearing loss did not change the results substantially. CONCLUSIONS: The findings of this systematic review and meta-analysis of observational studies suggest that hearing loss increases the risk of frailty in later life. Whether this relationship is causal remains to be determined.

Teleaudiology hearing aid fitting follow-up consultations for adults: single blinded crossover randomised control trial and cohort studies.

OBJECTIVE: To evaluate and compare the effectiveness and quality of standard face-to-face and teleaudiology hearing aid fitting follow-up consultations and blended services for adult hearing aid users. DESIGN AND STUDY SAMPLE: Fifty-six participants were randomly allocated to two equal groups, with equal numbers of new and experienced users. One standard and one teleaudiology follow-up consultation were delivered by an audiologist, the latter assisted by a facilitator. The order was reversed for the second group. Outcome measurement tools were applied to assess aspects of participants' communication, fitting (physical, sensorial), quality of life, and service. Cross-sectional and longitudinal outcomes were analysed. RESULTS: Most participants presented with moderate, sloping, and symmetrical sensorineural hearing loss. The duration of teleaudiology (42.96 ± 2.73 min) was equivalent to face-to-face consultations (41.25 ± 2.61 min). All modes of service delivery significantly improved outcomes for communication, fitting, and quality of life (p > 0.05). Satisfaction for both consultation modes was high, although significantly greater with standard consultations. The mode and order of delivery of the consultations did not influence the outcomes. CONCLUSION: Teleaudiology hearing aid follow-up consultations can deliver significant improvements, and do not differ from standard consultations. Blended services also deliver significant improvements. Satisfaction can be negatively impacted by technical or human-related issues.

Multimode binding and stimuli responsive displacement of acridine orange dye complexed with p-sulfonatocalix[4/6]arene macrocycles.

Interaction of acridine orange (AOH+) dye with water soluble anionic p-sulfonatocalix[n]arene (SCXn) hosts, SCX4 and SCX6, having different cavity dimensions, has been investigated using multispectroscopic techniques. Intriguing modulation in the photophysical properties of AOH+ upon interaction with SCXn hosts indicate the formation of different host-guest complexes at different regions of the host concentrations. At lower host concentrations, AOH+ undergoes SCXn assisted aggregation, causing a drastic reduction in fluorescence intensity. At higher host concentrations, aggregated-AOH+-SCXn complexes disintegrate and monomeric-AOH+-SCXn exo and inclusion complexes are eventually formed, leading to a huge fluorescence enhancement finally. Observed effects are more pronounced with SCX6 as compared to SCX4 host. Time-resolved fluorescence studies indicate that at very high host concentrations, there is also a diffusion-controlled dynamic quenching for both monomeric-AOH+-SCXn exo and inclusion complexes, caused by the free SCXn present in the solution, a phenomenon not reported before for such host-guest systems. The aggregated-AOH+-SCXn complexes at lower host concentration were employed to investigate displacement study using an antiviral drug, 1-adamantanamine (AD) and a neurotransmitter, acetylcholine (AcCh), as the competitive binders cum external stimuli, which resulted in a drastic recovery of the fluorescence reduced initially due to aggregation process. Though both the AOH+-SCXn systems act as efficient supramolecular assemblies in sensing AD and AcCh as the analytes through fluorescence "OFF-ON" mechanism, the effect is more pronounced for AOH+-SCX4 system as compared to AOH+-SCX6. SCXn induced interesting modulation in the photophysical properties of AOH+ and the stimulus responsive dye displacement observed for aggregated-AOH+-SCXn systems can expectedly find applications in fluorescence OFF-ON sensing, supramolecular functional materials and similar others.

Hearing aids to support cognitive functions of older adults at risk of dementia: the HearCog trial- clinical protocols.

BACKGROUND: Globally, about 50 million people were living with dementia in 2015, with this number projected to triple by 2050. With no cure or effective treatment currently insight, it is vital that factors are identified which will help prevent or delay both age-related and pathological cognitive decline and dementia. Observational data have suggested that hearing loss is a potentially modifiable risk factor for dementia, but no conclusive evidence from randomised controlled trials is currently available. METHODS: The HearCog trial is a 24-month, randomised, controlled clinical trial aimed at determining whether a hearing loss intervention can delay or arrest the cognitive decline. We will randomise 180 older adults with hearing loss and mild cognitive impairment to a hearing aid or control group to determine if the fitting of hearing aids decreases the 12-month rate of cognitive decline compared with the control group. In addition, we will also determine if the expected clinical gains achieved after 12 months can be sustained over an additional 12 months and if losses experienced through the non-correction of hearing loss can be reversed with the fitting of hearing aids after 12 months. DISCUSSION: The trial will also explore the cost-effectiveness of the intervention compared to the control arm and the impact of hearing aids on anxiety, depression, physical health and quality of life. The results of this trial will clarify whether the systematic correction of hearing loss benefits cognition in older adults at risk of cognitive decline. We anticipate that our findings will have implications for clinical practice and health policy development. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry ( ANZCTR: 12618001278224 ), registered on 30.07.2018.

The effect of hearing loss configuration on cochlear implantation uptake rates: an Australian experience.

Objective: Recent changes to cochlear implant (CI) candidacy criteria have led to the inclusion of candidates with greater levels of hearing in the contralateral and/or implanted ear. This study assessed the impact of various hearing loss configurations on CI uptake rates (those assessed as eligible for CI, who proceed to CI).Design: Retrospective cohort study.Study sample: Post-lingually deaf adult CI candidates (n = 619) seen at a Western Australian cochlear implant clinic.Results: An overall CI uptake rate of 44% was observed. Hearing loss configuration significantly impacted uptake rates. Uptake rates of 62% for symmetrical hearing loss, 48% for asymmetrical hearing loss (four-frequency average hearing loss (4FAHL) asymmetry ≤60 dB), 25% for highly asymmetrical hearing loss (4FAHL asymmetry >60 dB), 38% for hearing losses eligible for electric-acoustic stimulation, and 22% for individuals with single-sided hearing loss were observed. Hearing loss configuration and age were both significant factors in relation to CI uptake although the impact of age was limited.Conclusion: CI clinics who apply or are considering applying expanded CI candidacy criteria within their practice should be aware that candidates with greater levels of residual hearing in at least the contralateral ear are less likely to proceed to CI.

Retinal vascular abnormalities in schizophrenia and bipolar disorder: A window to the brain.

OBJECTIVES: The examination of retinal microvascular abnormalities through fundus photography is currently the best available non-invasive technique for assessment of cerebral vascular status. Several studies in the last decade have reported higher incidences of adverse cerebrovascular events in Schizophrenia (SCZ) and bipolar disorder (BD). However, retinal microvasculature abnormalities in SCZ and BD have remained under-explored, and no study has compared this aspect of SCZ and BD till date. METHODS: Retinal Images of 100 SCZ patients, BD patients, and healthy volunteers each were acquired by trained individuals using a non-mydriatic camera with a 40-degree field of view. The retinal images were quantified using a valid semi-automated method. The average of left and right eye diameters of the venules and arterioles passing through the extended zone between 0.5 and 2 disc diameters from the optic disc were calculated. RESULTS: The groups differed significantly with respect to average diameters of both retinal venules (P < 0.001) and retinal arterioles (P < 0.001), after controlling for age and sex. Both SCZ and BD patients had significantly narrower arterioles and wider venules compared to HV. There were also significant differences between SCZ and BD patients; patients with BD had narrower arterioles and wider venules. CONCLUSION: Considering the affordability and easy accessibility of the investigative procedure, retinal microvascular examination could serve as a potential screening tool to identify individuals at risk for adverse cerebrovascular events. The findings of the current study also provide a strong rationale for further systematic examination of retinal vascular abnormalities in SCZ and BD.

Examination of retinal vascular trajectory in schizophrenia and bipolar disorder.

AIM: Evidence suggests microvascular dysfunction (wider retinal venules and narrower arterioles) in schizophrenia (SCZ) and bipolar disorder (BD). The vascular development is synchronous with neuronal development in the retina and brain. The retinal vessel trajectory is related to retinal nerve fiber layer thinning and cerebrovascular abnormalities in SCZ and BD and has not yet been examined. Hence, in this study we examined the retinal vascular trajectory in SCZ and BD in comparison with healthy volunteers (HV). METHODS: Retinal images were acquired from 100 HV, SCZ patients, and BD patients, respectively, with a non-mydriatic fundus camera. Images were quantified to obtain the retinal arterial and venous trajectories using a validated, semiautomated algorithm. Analysis of covariance and regression analyses were conducted to examine group differences. A supervised machine-learning ensemble of bagged-trees method was used for automated classification of trajectory values. RESULTS: There was a significant difference among groups in both the retinal venous trajectory (HV: 0.17 ± 0.08; SCZ: 0.25 ± 0.17; BD: 0.27 ± 0.20; P < 0.001) and the arterial trajectory (HV: 0.34 ± 0.15; SCZ: 0.29 ± 0.10; BD: 0.29 ± 0.11; P = 0.003) even after adjusting for age and sex (P < 0.001). On post-hoc analysis, the SCZ and BD groups differed from the HV on retinal venous and arterial trajectories, but there was no difference between SCZ and BD patients. The machine learning showed an accuracy of 86% and 73% for classifying HV versus SCZ and BD, respectively. CONCLUSION: Smaller trajectories of retinal arteries indicate wider and flatter curves in SCZ and BD. Considering the relation between retinal/cerebral vasculatures and retinal nerve fiber layer thinness, the retinal vascular trajectory is a potential marker for SCZ and BD. As a relatively affordable investigation, retinal fundus photography should be further explored in SCZ and BD as a potential screening measure.

Cytology and direct human papillomavirus testing on fine needle aspirates from cervical lymph node metastases of patients with oropharyngeal squamous cell carcinoma or occult primary.

OBJECTIVE: Cervical lymph node fine needle aspirates (FNAs) may represent the only specimens available for an initial characterisation of patients with lymphadenopathy. Morphology and human papillomavirus (HPV) DNA presence were evaluated in FNAs collected from patients with oropharyngeal squamous cell carcinoma (OPSCC) or cancer of unknown primary (CUP). FNA HPV results were compared with those of the respective formalin-fixed paraffin-embedded (FFPE) primary cancer. METHODS: Liquid-based cytology was performed on FNAs collected in PreservCyt. HPV-DNA was analysed by the INNO-LiPA HPV genotyping Extra II on both cytological and FFPE samples. The CINtec® Histology Kit was used to assess p16 expression in cancer tissues. RESULTS: Forty-seven FNAs were collected from OPSCC and 16 from CUP patients. Cancer cells were found in 35/47 cases (74.5%), while 11 (23.4%) showed only necrosis and one (2.1%) was negative for malignancy. HPV-DNA was detected in 30/47 FNAs (63.8%), mostly harbouring HPV16 (90.0%). An excellent agreement was observed between the FNA and corresponding FFPE HPV status (raw agreement: 97.5%; Cohen κ: 0.94). The HPV test result on the necrotic FNAs completely matched that of the respective primary cancer. FNA HPV testing correctly identified 26/27 HPV-driven OPSCCs (96.3%). HPV was detected in nine of 16 FNAs (56.2%) from CUP patients. CONCLUSIONS: HPV status of metastatic cervical lymph node FNAs reflects that of the corresponding primary OPSCCs even when cell integrity in the FNA is not preserved and only necrotic debris are present. In patients with initial CUP, HPV-positivity on the FNA may guide the diagnostic workup and therapeutic management, since it suggests an oropharyngeal origin.

Selective attentional processes in cochlear implant recipients: Measurements of the attentional filter.

In normal hearing subjects, detection of near-threshold tones in noise is influenced by signal certainty. Thus, tones that are presented more frequently than others, and/or are preceded by a clearly audible cue tone of the same frequency (target tones) are detected better than other tones (probe tones). This auditory attentional filter was examined in six cochlear implant (CI) recipients, using acoustic stimuli and direct programmed electrode stimulation. Three of the subjects showed no evidence of an attentional filter. Three subjects showed a relatively higher detection rate of the target frequency or electrode stimulated during the attentional task, and in two of these subjects the target benefit was influenced by stimulus certainty. The absence of an attentional filter in some CI recipients is consistent with suggestions that the attentional filter may be generated by efferent modulation of outer hair cells, which would presumably be absent in CI recipients, however, the presence of some frequency-selective attentional effects and a near-normal attentional filter in two CI subjects imply that central processes can modulate signal detection in CI recipients according to stimulus certainty. Such central processes might serve as a neural substrate to improve signal detection in CI recipients.

Environmentally induced transgenerational changes in seed longevity: maternal and genetic influence.

BACKGROUND AND AIMS: Seed longevity, a fundamental plant trait for ex situ conservation and persistence in the soil of many species, varies across populations and generations that experience different climates. This study investigates the extent to which differences in seed longevity are due to genetic differences and/or modified by adaptive responses to environmental changes. METHODS: Seeds of two wild populations of Silene vulgaris from alpine (wA) and lowland (wL) locations and seeds originating from their cultivation in a lowland common garden for two generations (cA1, cL1, cA2 and cL2) were exposed to controlled ageing at 45 °C, 60 % relative humidity and regularly sampled for germination and relative mRNA quantification (SvHSP17.4 and SvNRPD12). KEY RESULTS: The parental plant growth environment affected the longevity of seeds with high plasticity. Seeds of wL were significantly longer lived than those of wA. However, when alpine plants were grown in the common garden, longevity doubled for the first generation of seeds produced (cA1). Conversely, longevity was similar in all lowland seed lots and did not increase in the second generation of seeds produced from alpine plants grown in the common garden (cA2). Analysis of parental effects on mRNA seed provisioning indicated that the accumulation of gene transcripts involved in tolerance to heat stress was highest in wL, cL1 and cL2, followed by cA1, cA2 and wA. CONCLUSIONS: Seed longevity has a genetic basis, but may show strong adaptive responses, which are associated with differential accumulation of mRNA via parental effects. Adaptive adjustments of seed longevity due to transgenerational plasticity may play a fundamental role in the survival and persistence of the species in the face of future environmental challenges. The results suggest that regeneration location may have important implications for the conservation of alpine plants held in seed banks.

Continuous increase in HIV-1 incidence after the year 2000 among men who have sex with men in Rome: insights from a 25-year retrospective cohort study.

To assess trends in HIV-1 incidence and risk factors for seroconversion among men who have sex with men (MSM) resident in Rome, Italy, a retrospective longitudinal cohort study was conducted over 25 years. Incidence rates and trends were modelled using Poisson regression and risk factors were assessed by multivariate Cox models. Of 1,862 HIV-1-negative individuals, 347 seroconverted during follow-up. HIV-1 incidence rates increased from 5.2/100 persons/year (p/y) in 1986 (95% confidence interval (CI): 2.3­11.5) to 9.2/00 p/y in 1992 (95% CI: 6.4­13.0), decreased to 1.3/100 p/y in 2001 and increased until 2009 (11.7/100 p/y; 95% CI: 7.4­18.6). The risk of HIV-1 seroconversion increased during the study period in younger MSM (incidence rate ratio (IRR) = 17.18; 95% CI: 9.74­30.32 in 16­32 year-olds and IRR = 5.09; 95% CI: 2.92­8.87 in 33­41 year-olds) and in those who acquired syphilis (IRR = 7.71; 95% CI: 5.00­11.88). In contrast, the risk of seroconversion decreased among highly educated MSM (IRR = 0.54; 95% CI: 0.35­0.82) and those without Italian citizenship (IRR = 0.45; 95% CI: 0.28­0.71). The HIV epidemic in MSM living in Rome continues to expand. Targeted prevention programmes against sexually transmitted infections to enhance knowledge transfer and behavioural skills are urgently required.

DNA profiling, telomere analysis and antioxidant properties as tools for monitoring ex situ seed longevity.

BACKGROUND AND AIMS: The germination test currently represents the most used method to assess seed viability in germplasm banks, despite the difficulties caused by the occurrence of seed dormancy. Furthermore, seed longevity can vary considerably across species and populations from different environments, and studies related to the eco-physiological processes underlying such variations are still limited in their depth. The aim of the present work was the identification of reliable molecular markers that might help in monitoring seed deterioration. METHODS: Dry seeds were subjected to artificial ageing and collected at different time points for molecular/biochemical analyses. DNA damage was measured using the RAPD (random amplified polymorphic DNA) approach while the seed antioxidant profile was obtained using both the DPPH (1,1-diphenyl, 2-picrylhydrazyl) assay and the Folin-Ciocalteu reagent method. Electron paramagnetic resonance (EPR) provided profiles of free radicals. Quantitative real-time polymerase chain reaction (QRT-PCR) was used to assess the expression profiles of the antioxidant genes MT2 (type 2 metallothionein) and SOD (superoxide dismutase). A modified QRT-PCR protocol was used to determine telomere length. KEY RESULTS: The RAPD profiles highlighted different capacities of the two Silene species to overcome DNA damage induced by artificial ageing. The antioxidant profiles of dry and rehydrated seeds revealed that the high-altitude taxon Silene acaulis was characterized by a lower antioxidant specific activity. Significant upregulation of the MT2 and SOD genes was observed only in the rehydrated seeds of the low-altitude species. Rehydration resulted in telomere lengthening in both Silene species. CONCLUSIONS: Different seed viability markers have been selected for plant species showing inherent variation of seed longevity. RAPD analysis, quantification of redox activity of non-enzymatic antioxidant compounds and gene expression profiling provide deeper insights to study seed viability during storage. Telomere lengthening is a promising tool to discriminate between short- and long-lived species.

Kinetic Measurements to Investigate the Oxygen-Sensing Properties of Plant Cysteine Oxidases.

Enzymatic O2 sensors transduce the availability of O2 within the cell into a physiological, typically adaptive response. One such O2-sensing enzymatic family is the N-terminal cysteine dioxygenases in plants (plant cysteine oxidases [PCOs]). In vitro kinetic studies have determined the O2-sensing capacity of PCOs. Here we describe the rationale and experimental protocol for an assay with which the O2 sensitivity of Arabidopsis thaliana PCOs (AtPCOs) can be measured. We explain each step from the recombinant protein synthesis of AtPCOs to the steady-state kinetic assays of AtPCOs for primary substrate and O2 from which kinetic parameters can be derived. The same techniques can be applied to other N-terminal cysteine thiol dioxygenases, e.g. 2-aminoethanethiol dioxygenase (ADO), and similar principles can be applied to determine kinetic characteristics of other oxygenase enzymes towards O2.