802 CONCURRENT PATHOLOGIES OBSERVED IN OLDER ADULTS WITH COVID-19 INFECTION

Introduction

This study aimed to look at the effect of frailty and multi morbidity on short-term outcomes in patients diagnosed with COVID-19 in a hospital setting, looking specifically at the variety of concurrent pathologies diagnosed during their admission and how these affected the course of their illness and mortality.

Methods

The study took place at Glasgow Royal Infirmary. We retrospectively collected data from 280 patients who were admitted to the medicine for the elderly department between the 1st October and 1st December 2020 and diagnosed with COVID-19.

Results

In this cohort, 65% of older adults in hospital with COVID-19 had their admissions complicated by concurrent pathologies; most commonly delirium, acute kidney injury and pulmonary embolism, also increasing mortality in this group. It was also found that 39% of patients in this group had co-pathologies that were not necessarily associated with COVID-19 disease, for example AKI, AF and stroke/TIA. 35% of older adults in this group had no concurrent medical diagnoses during their admission, however this did not correlate with reduced mortality in this group.

Conclusion

The data highlights the vulnerability of older adults with COVID-19 infection making them more susceptible to concurrent disease and contributing to further morbidity and mortality. We also found a large number of patients had co-pathologies not associated with COVID-19 disease, highlighting the importance of considering other diagnoses in frail elderly patients.

Use of Auditory Evoked Responses as a Measure of Recovery from Benzodiazepine Sedation

The amplitude of the P300 component of auditory evoked responses was found to be depressed by benzodiazepine sedation and was subsequently used to monitor the recovery of volunteers sedated with midazolam. The amplitude of the evoked responses was found to be highly correlated with blood midazolam levels but to be no more sensitive than standard psychomotor testing in assessing recovery from sedation.

Cognitive bias modification for facial interpretation: a randomized controlled trial of transfer to self-report and cognitive measures in a healthy sample

Cognitive bias modification is a potential low-intensity intervention for mood disorders, but previous studies have shown mixed success. This study explored whether facial interpretation bias modification (FIBM), a similar paradigm designed to shift emotional interpretation (and/or perception) of faces would transfer to: (i) self-reported symptoms and (ii) a battery of cognitive tasks. In a preregistered, double-blind randomized controlled trial, healthy participants received eight online sessions of FIBM (N = 52) or eight sham sessions (N = 52). While we replicate that FIBM successfully shifts ambiguous facial expression interpretation in the intervention group, this failed to transfer to the majority of self-report or cognitive measures. There was, however, weak, inconclusive evidence of transfer to a self-report measure of stress, a cognitive measure of anhedonia, and evidence that results were moderated by trait anxiety (whereby transference was greatest in those with higher baseline symptoms). We discuss the need for work in both larger and clinical samples, while urging caution that these FIBM training effects may not transfer to clinically relevant domains.

Gamification for health promotion: systematic review of behaviour change techniques in smartphone apps

OBJECTIVE

Smartphone games that aim to alter health behaviours are common, but there is uncertainty about how to achieve this. We systematically reviewed health apps containing gaming elements analysing their embedded behaviour change techniques.

METHODS

Two trained researchers independently coded apps for behaviour change techniques using a standard taxonomy. We explored associations with user ratings and price.

DATA SOURCES

We screened the National Health Service (NHS) Health Apps Library and all top-rated medical, health and wellness and health and fitness apps (defined by Apple and Google Play stores based on revenue and downloads). We included free and paid English language apps using 'gamification' (rewards, prizes, avatars, badges, leaderboards, competitions, levelling-up or health-related challenges). We excluded apps targeting health professionals.

RESULTS

64 of 1680 (4%) health apps included gamification and met inclusion criteria; only 3 of these were in the NHS Library. Behaviour change categories used were: feedback and monitoring (n=60, 94% of apps), reward and threat (n=52, 81%), and goals and planning (n=52, 81%). Individual techniques were: self-monitoring of behaviour (n=55, 86%), non-specific reward (n=49, 82%), social support unspecified (n=48, 75%), non-specific incentive (n=49, 82%) and focus on past success (n=47, 73%). Median number of techniques per app was 14 (range: 5-22). Common combinations were: goal setting, self-monitoring, non-specific reward and non-specific incentive (n=35, 55%); goal setting, self-monitoring and focus on past success (n=33, 52%). There was no correlation between number of techniques and user ratings (p=0.07; r_s=0.23) or price (p=0.45; r_s=0.10).

CONCLUSIONS

Few health apps currently employ gamification and there is a wide variation in the use of behaviour change techniques, which may limit potential to improve health outcomes. We found no correlation between user rating (a possible proxy for health benefits) and game content or price. Further research is required to evaluate effective behaviour change techniques and to assess clinical outcomes.

TRIAL REGISTRATION NUMBER

CRD42015029841.

An integrated view of data quality in Earth observation

Data quality is a difficult notion to define precisely, and different communities have different views and understandings of the subject. This causes confusion, a lack of harmonization of data across communities and omission of vital quality information. For some existing data infrastructures, data quality standards cannot address the problem adequately and cannot fulfil all user needs or cover all concepts of data quality. In this study, we discuss some philosophical issues on data quality. We identify actual user needs on data quality, review existing standards and specifications on data quality, and propose an integrated model for data quality in the field of Earth observation (EO). We also propose a practical mechanism for applying the integrated quality information model to a large number of datasets through metadata inheritance. While our data quality management approach is in the domain of EO, we believe that the ideas and methodologies for data quality management can be applied to wider domains and disciplines to facilitate quality-enabled scientific research.

Colic after swimming exercise in racehorses: an investigation of incidence, management, surgical findings and outcome

The incidence of colic following swimming exercise (SC) in a racehorse population examined over 3 years was 0.08%. Following 167,977 swims, 136 cases were reported. Colic resolved spontaneously in 2 horses, medically in 129 or surgically in 5. In a separate study, 21 horses were subject to exploratory laparotomy for SC. Findings included non-strangulating displacements in 7 horses, strangulating displacements in 7, a combination of non-strangulating and strangulating displacements in 1, prominent gaseous intestinal distension in 5 and no abnormalities in 1 horse. A poor response to analgesia prompted surgery in all cases. Rectal palpation and/or abdominal ultrasound was performed in 16 of 21 cases and abnormalities were found in 14 of these. Of the 21 surgical cases, 20 (95.2%) survived to discharge and 18 (90%) raced postoperatively.

Instrumental learning and relearning in individuals with psychopathy and in patients with lesions involving the amygdala or orbitofrontal cortex

Previous work has shown that individuals with psychopathy are impaired on some forms of associative learning, particularly stimulus-reinforcement learning (Blair et al., 2004; Newman & Kosson, 1986). Animal work suggests that the acquisition of stimulus-reinforcement associations requires the amygdala (Baxter & Murray, 2002). Individuals with psychopathy also show impoverished reversal learning (Mitchell, Colledge, Leonard, & Blair, 2002). Reversal learning is supported by the ventrolateral and orbitofrontal cortex (Rolls, 2004). In this paper we present experiments investigating stimulus-reinforcement learning and relearning in patients with lesions of the orbitofrontal cortex or amygdala, and individuals with developmental psychopathy without known trauma. The results are interpreted with reference to current neurocognitive models of stimulus-reinforcement learning, relearning, and developmental psychopathy.

Subchondral cystic lesions of the proximal extremity of the tibia in horses: 12 cases (1983-2000)

OBJECTIVE

To determine clinical and radiographic features of subchondral cystic lesions (SCL) of the proximal extremity of the tibia in horses that could be used to classify these lesions as being related to osteochondrosis or osteoarthritis and to evaluate results of surgical debridement.

DESIGN

Retrospective study.

ANIMALS

12 horses with 14 SCL.

PROCEDURE

Medical records and radiographs obtained before and after treatment were reviewed.

RESULTS

In 6 young horses (8 lesions), SCL were considered to be related to osteochondrosis; all involved the lateral tibial condyle. The remaining 6 horses were mature and had radiographic evidence of osteoarthritis in addition to SCL. Arthroscopic debridement was performed in 4 horses in which lesions were considered to be a result of osteochondrosis and in 3 horses with osteoarthritis. Three horses in which SCL were considered to be a result of osteochondrosis performed athletically after debridement. Two horses with moderate osteoarthritis returned to work after arthroscopic debridement but at a lower level of athletic performance. One horse with SCL related to osteochondrosis responded to medical treatment and went on to race.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that arthroscopic debridement of SCL is feasible in horses in which lesions involve the cranial portion of the lateral or medial tibial condyle, and that treated horses may be able to perform athletically.

Dissociation between 'theory of mind' and executive functions in a patient with early left amygdala damage

There have been recent suggestions that the amygdala may be involved in the development or mediation of 'theory of mind'. We report a patient, B.M., with early or congenital left amygdala damage who, by adulthood, had received the psychiatric diagnoses of schizophrenia and Asperger's syndrome. We conducted a series of experimental investigations to determine B.M.'s cognitive functioning. In line with his diagnoses, B.M. was found to be severely impaired in his ability to represent mental states. Following this, we conducted a second series of studies to determine B.M.'s executive functioning. In the literature, there have been frequent claims that theory of mind is mediated by general executive functioning. B.M. showed no indication of executive function impairment, passing 16 tests assessing his ability to inhibit dominant responses, create and maintain goal-related behaviours, and temporally sequence behaviour. The findings are discussed with reference to models regarding the role of the amygdala in the development of theory of mind and the degree of dissociation between theory of mind and executive functioning. We conclude that theory of mind is not simply a function of more general executive functions, and that executive functions can develop and function on-line, independently of theory of mind. Moreover, we conclude that the amygdala may play some role in the development of the circuitry mediating theory of mind.

Activation of p38 MAP kinase in T cells facilitates the immune response to the influenza virus

Activation of p38 MAP kinase in T cells leads to increased interferon-gamma production in CD4+ and CD8+ T cells, and the selective cell death of CD8+ T cells. To address the role of p38 MAP kinase activation in T cells during an in vivo immune response, we examined the response against the influenza virus in transgenic mice expressing a constitutively activated MKK6 (MKK6(Glu)), an upstream activator of p38 MAP kinase. Activated CD4+ T cells accumulate in the lung and mediastinal lymph node of both wild-type and MKK6(Glu) transgenic mice upon intranasal inoculation with the influenza virus. MKK6(Glu) CD8+ T cells, however, disappear rapidly from the mediastinal lymph node but accumulate in the lung tissue. We demonstrate that interleukin-6, a cytokine produced by lung epithelial cells, partially protects CD8+ T cells from the cell death induced by p38 MAP kinase activation. During the influenza infection in MKK6(Glu) transgenic mice, reduced virus titers were also observed despite a normal B-cell antibody response. These results indicate that the activation of p38 MAP kinase in T cells affects the in vivo antiviral immune response.

Repetitive and non-repetitive violent offending behaviour in male patients in a maximum security mental hospital--clinical and neuroimaging findings

OBJECTIVE

To examine if different violent offending behaviours are associated with different clinical and neuroimaging profiles.

METHOD

Thirty-nine schizophrenic and schizoaffective offenders from a maximum security mental hospital-20 repetitive violent offenders (RVOs) and 19 non-repetitive violent offenders (NRVOs)-were selected for clinical and neuroimaging assessments.

RESULTS

Both groups had positive family history of mental illness and violence. Age, diagnosis, duration of illness, victim profiles and use of weapons at the time of the index offence were similar. RVOs had a higher prevalence of early parental separation, juvenile conduct problem, previous convictions of crimes not involving violence, impulsive suicide attempts, delusion of their lives being threatened at the time of the index offence and electroencephalographic (EEG) abnormalities localized to temporal lobes. NRVOs had a higher prevalence of sexual inexperience and command hallucinations to kill at the time of the index offence. Asymmetric gyral patterns at the temporo-parietal region were particularly common in RVOs and absent in NRVOs. Non-specific white matter changes in magnetic resonance imaging (MRI) and generalized cortical hypometabolism in positron emission tomography (PET) were present in both groups.

CONCLUSIONS

Different structural and metabolic changes in the brain were associated with different violent offending behaviours. The complex interaction between violent behaviour, clinical features and neuroimaging findings in schizophrenia requires further studies.

Positron emission tomography in male violent offenders with schizophrenia

The FDG PET brain scans from 31 offenders with schizophrenia and schizoaffective disorder from a maximum security mental hospital were compared with those of normal controls (N = 6) in terms of relative FDG uptake in a range of regions covering frontal and temporal regions. The patient sample was divided into those who had a history of repetitive violent offending (RVO, N = 17) and those without a repetitive violent history (NRVO, N = 14) according to the violence rating of their pre-admission convictions. Reduced FDG uptake was noted at both the right and left anterior inferior temporal (R and L AIT) regions in NRVOs but only at LAIT in RVOs. NRVOs had significantly lower FDG uptake at RAIT than RVOs. The findings suggest that metabolic changes at AIT may be related to different patterns of violent offending in patients with schizophrenia.

The post-concussional state: neurophysiological aspects

BACKGROUND

Twenty-six young men admitted to an Accident and Emergency Department for observation following a minor closed head injury (post-traumatic amnesia (PTA) less than 12 hours) were investigated within 24 hours of admission (day 0) and followed up at 10 days, 6 weeks and 1 year after the trauma.

METHOD

Investigations at day 0 included physical examination, completion of post-concussional symptom and stress-arousal checklists, computerised EEG (CEEG) and auditory brainstem evoked potential (BAEP) recordings. These were repeated at ten days and six weeks. At 12 months follow-up, the Present State Examination (PSE) was carried out and a further post-concussional symptom checklist completed.

RESULTS

Post-concussional symptomatology declined progressively from day 0 but half had residual symptoms at 1 year. Seventy-two per cent ran an acute course with recovery by 6 weeks, 8% chronic unremitting course and 20% initially improved but had an exacerbation of symptoms between 6 weeks and 12 months. The CEEG alpha-theta ratios decreased significantly between days 0 and 10, reaching a baseline thereafter. Measures of CEEG recovery from all channels correlated with symptom counts at six weeks; the slower the recovery the greater the symptoms. A relative delay in left temporal recovery was associated with residual psychiatric morbidity (PSE ID scores) at 12 months. Prolonged central brainstem conduction times occurred in 27% of patients at day 0. These correlated positively with PTA and degree of psychiatric morbidity (PSE ID scores) at 12 months.

CONCLUSIONS

Symptom chronicity was accompanied by continuing brainstem dysfunction, while the degree of transient cortical dysfunction appeared to have a direct influence in the intensity of early organic symptom reaction to the trauma. Levels of perceived stress at the time of the injury, or afterwards, were not related to symptom formation.

Activation sequence of discrete brain areas during cognitive processes: results from magnetic field tomography

Magnetic field tomography is a technique for extracting 3-dimensional estimates of current density in the brain, from non-contact, non-invasive measurements of the magnetic field generated by the brain. It allows visualisation of both cortical and subcortical focal activation patterns at millisecond intervals, and the relative time difference between active cortical areas. We have used this technique to study the activation history of discrete brain regions associated with the preparation for, initiation and inhibition of movement, and movement itself in a CNV paradigm. The strongest focal activities are found within well defined cortical regions, namely the auditory (A1), sensorimotor (SM1), medial parietal area (MPA) and anterior supplementary motor area (SMA). For the movement condition, activation history differs for the warning stimulus and the stimulus initiating movement.

Electroencephalography, computed tomography and violence ratings of male patients in a maximum-security mental hospital

A retrospective study of brain investigations of 372 male patients in a maximum-security mental hospital patients is described. All computed tomography (CT) scan and electroencephalography (EEG) reports were collected and rated blind; patients were subsequently divided into 3 groups according to the violence rating of their pre-admission offending behaviour. The 3 groups were similar in their mean age, psychiatric diagnosis, Wechsler Adult Intelligence Scale score and proportions of patients investigated with EEG and CT. In the most violent group, 20% had focal temporal electrical abnormalities on EEG (slowing and/or sharp waves) and 41% had structural abnormalities localised to temporal lobe on CT (dilated temporal horn and/or reduced size of temporal lobe). The corresponding figures for the least violent group are 2.4% and 6.7% respectively. These results suggest that high violence rating scores are associated with temporal lobe abnormalities on CT and abnormal temporal electrical discharges on EEG.

Petechial haemorrhage following a partial seizure with secondary generalization: atypical presentation and differential diagnosis

A case is reported of a patient who had a respiratory arrest on a high dependency ward in a High Security Hospital with an unusual presentation. The patient had head and upper abdominal petechial haemorrhages with extensive conjunctival haemorrhaging. A considered antecedent for this potentially life-threatening presentation was strangulation. Analysis of all the available clinical information supports the hypothesis that he had a single tonic-clonic seizure with a focal-motor onset. This constitutes an unusual consequence of a partial seizure with secondary generalization.

Responses of mucus-producing cells in gill disease of rainbow trout (Oncorhynchus mykiss)

This paper documents the responses of mucus-producing cells in the gills of rainbow trout (Oncorhynchus mykiss) throughout a naturally occurring outbreak of bacterial gill disease (BGD) and following exposure to experimentally induced high concentrations of ammonia and suspended solids. The responses were examined at three sites on the gill filament with three histochemical stains selected to identify the main types of mucous glycoproteins; these were periodic acid-Schiff (PAS), alcian blue pH 2.5 (AB2) and alcian blue pH 1.0 (AB1). In the BGD-infected fish, there was an increase in the numbers of PAS-positive and AB2-positive mucous cells and a corresponding decrease in AB1-positive cells. The greatest increase in mucus-producing cells occurred at the tips of the filaments, but the greatest relative change occurred at the mid-filamental (inter-lamellar) position. Fish exposed to high ammonia concentrations also had elevated numbers of mucus-producing cells, but there was no statistically significant change in fish exposed to high amounts of kaolin. The possible implications of these findings are discussed.

Efficacy of albendazole against Strongyloides ratti and S. stercoralis in vitro, in mice, and in normal and immunosuppressed dogs

In view of conflicting clinical reports, the effects of albendazole on Strongyloides were examined in vitro and in experimentally-infected animals. Albendazole inhibited the hatching and moulting of S. ratti eggs and larvae and prevented the development in vitro of S. stercoralis first-stage larvae. Pre-exposure to the drug did not impair the infectivity of either S. ratti or S. stercoralis third-stage larvae. Albendazole had a dose-dependent inhibitory effect on S. ratti migrating larvae in mice when measured in terms of the numbers of larvae recovered from the skin or lungs or the subsequent development of a patent infection. Likewise, killing of adult S. ratti in the gut and eradication of S. stercoralis third-stage larvae from the muscles of mice were dose-dependent. Albendazole in a dose of 100 mg twice daily for three days given at the time of infection with S. stercoralis of immunocompetent dogs prevented completely the subsequent development of patent infection. When the drug was given in the same dosage to immunosuppressed dogs with patent infections, the larvae disappeared from the stools transiently; when the animals were killed seven weeks after treatment, small numbers of adult worms and rhabditiform larvae were found in the gut. It is concluded that albendazole may be effective treatment for strongyloidiasis if it is given in sufficiently large doses.

The contingent negative variation (CNV) to fear-related stimuli in acquisition and extinction

Contingent Negative Variation (CNV) in anticipation of phobic and neutral slide material was recorded in Acquisition of a learned association between tone pitch and slide type, and in Extinction (following removal of slide presentation). In phobic volunteers, no clear CNV differentiation between 'phobic' and control condition was apparent in either Acquisition or Extinction. For Control subjects, a different pattern entirely has been demonstrated, with anticipation of the neutral condition giving rise to a larger CNV than anticipation of the 'phobic' condition (in Acquisition). In addition, Extinction led to a reversal of this CNV amplitude relationship, with the tone previously associated with the phobic slide producing a DC-shift which was larger than that following the tone previously paired with the neutral slide. The results are compatible with a dynamic model of CNV generation according to which CNV amplitude is positively related to an expectancy for reward or non-punishment but inversely related to an expectancy for punishment or non-reward.

Purification and partial characterization of high-molecular-weight forms of ectopic calcitonin from a human bronchial carcinoma cell line

Studies on the high-molecular-weight immunoreactive calcitonin produced ectopically in culture by an epidermoid bronchial carcinoma cell line are reported. In cell-exposed medium, the principal component has a molecular weight of 40000 and molecules of mol.wts. 13000 and 10000 also occur. Only a trace amount of material co-eluting with 35000-mol.wt. human calcitonin is detectable. None of the calcitonins show cross-reactivity with anti-corticotropin serum. The 40000-mol.wt. immunoreactive calcitonin is readily proteolysed to the 13000- and 10000-mol.wt. components, but the 10000-mol.wt. component behaves as a comparatively stable 'core' molecule. By using immunoprecipitation and high-pressure liquid chromatography (h.p.l.c.), it is possible to prepare radiochemically homogeneous 10000-mol.wt. immunoreactive calcitonin from cells grown in the presence of individual 35S- or 3H-labelled amino acids. Peptide mapping of enzymic digests of this material by h.p.l.c. shows that it contains peptides in common with synthetic human calcitonin.

Tumour calcitonin. Interaction with specific calcitonin receptors

The human epidermoid bronchial carcinoma (BEN) cell line has been shown to have specific membrane binding sites for calcitonin and to secrete high-molecular-weight forms (ranging from 40000 to 10000) of immunoreactive calcitonin. Synthetic salmon and human calcitonins and a thyroid extract of porcine calcitonin have been shown to displace 125I-labelled salmon calcitonin from the receptors in a dose-related fashion. The binding to these receptors of calcitonins derived from the BEN cell line and a medullary thyroid carcinoma with molecular weights ranging from 28000 to 3500 (both separated by gel-filtration chromatography) has been investigated. Neither major peaks of BEN-cell-line calcitonin showed receptor binding activity. Only one form of medullary thyroid carcinoma calcitonin, that which co-eluted with synthetic calcitonin monomer on gel-filtration chromatography, caused any significant displacement of labelled hormone from the receptors.

The subunit structure of the arom multienzyme complex of Neurospora crassa. Evidence from peptide 'maps' for the identity of the subunits

Evidence was obtained, from polyacrylamide-gel electrophoresis in the presence of urea and from peptide 'mapping' of specifically labelled cysteine-and methionine-containing peptides, that the two subunits of the arom multienzyme complex of Neurospora crassa are chemically very similar and possibly identical.

A study of the quaternary structure of Escherichia coli RNA polymerase using bis(imido esters)

The quaternary structure of Escherichia coli RNA polymerase has been studied by cross-linking with a periodate-cleavable bis(imido ester), N,N'-bis(2-carboximidoethyl)tartaramide dimethyl ester dihydrochloride (CETD). The cross-linked holoenzyme gives a characteristic five-band pattern after electrophoresis on sodium dodecyl sulfate-polyacrylamide gels. The components of each band have been unambiguously identified by (a) molecular-weight measurements, (b) comparisons of cross-linking patterns of holoenzyme and core enzyme, and (c) periodate cleavage of cross-links followed by a second dimension sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The bands are (1) alphabeta and alphabeta', (2) sigmabeta and sigmabeta', (3) alphasigmabeta', (4) betabeta', and (5) sigmabetabeta'. Bands 2 and 4 are the most prominent at low reagent concentrations (up to 2.5 mM) but band 5 becomes the most prominent at higher concentrations. There are no bands corresponding to alphaalpha and alphasigma; a faint band has been tentatively identified as alphabetabeta'. Shorter bis(imido esters) are much less effective cross-linking reagents than CETD and they do not give rise to any other cross-linked species. On the basis of these observations, a model for the subunit arrangement of RNA polymerase is proposed.

The subunit structure of the arom multienzyme complex of Neurospora crassa. A possible pentafunctional polypeptide chain

A new procedure for the purification of the arom multienzyme complex from Neurospora crassa is presented. Important factors are the inactivation of proteinases by phenylmethanesulphonyl fluoride and the use of cellulose phosphate as an affinity adsorbent. A homogeneous enzyme, with a specific shikimate dehydrogenase activity of 70 units/mg of protein, is obtained in 25% yield. Polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate, combined with cross-linking studies using dimethyl suberimidate, suggest that the complex is composed of two subunits of molecular weight 165000. Glycerol-density-gradient centrifugation indicates a molecular weight for the intact complex of about 270000. Evidence for the effects of proteolysis, both during the preparation and on storage of the purified complex, is presented, and previous reports in the literature of the occurrence of multiple subunits are discussed in this light.

Purification and physicochemical properties of superoxide dismutase from two photosynthetic microorganisms

Superoxide dismutase (EC 1.15.1.1) has been isolated and characterised from the blue-green alga Spirulina platensis and from aerobically-grown Rhodopseudomonas spheroides, a purple, non-sulphur bacterium. The former enzyme contains 1 gatom of iron and the latter 1 gatom of manganese per mol; both enzymes have a molecular weight of 37 000-38 000, being composed of two non-covalently joined subunits of equal size. Various spectral studies have been carried out including absorbance, circular dichroism and electron spin resonance. Catalytic activity has been studied as a function of pH and shows a decrease at alkaline pH values. The manganoenzyme is generally more stable to various potentially denaturing conditions and is resistant to inactivation by hydrogen peroxide. Amino acid compositions and N-terminal residue determinations are presented.