Biomedical subjects

M J Morrell

Publications and source records attributed to M J Morrell.

75 records · Page 5Linked to original sources

PubMedDate not supplied

Conversion of mannose to fructose by immobilized mannose isomerase from Pseudomonas cepacia.

The enzyme mannose isomerase (EC 5.3.1.7) catalyzes the isomerization of D-mannose and D-fructose. The conversion of mannose to fructose is the first step in the principal pathway of mannose dissimilation by Pseudomonas cepacia. This enzyme is induced during growth on medium containing mannose to levels three- to four-fold higher than observed during growth on glucose or citrate. Mannose isomerase was purified from extracts of mannose-grown P. cepacia and was efficiently immobilized onto a porous, noncompressible, ceramic support. The performance of the immobilized enzyme, compared with the soluble enzyme, was evaluated under a variety of operating conditions to examine its potential for use in a process for the production of fructose syrups containing a higher proportion of fructose than is currently possible using glucose isomerase.

Aldose-Ketose Isomerases↗

PubMedDate not supplied

Speech during partial seizures: intracranial EEG correlates.

Vocalization during a seizure may help predict the location of seizure onset or identify structures ultimately involved in the seizure. Spontaneous vocalization during seizures was studied retrospectively in 22 patients with refractory complex partial seizures evaluated with bilateral intracranial electrodes. Of 22 patients, 12 vocalized during seizures. Seizures were as likely to originate from language-dominant (6/12) as from language-nondominant mesial temporal cortex (6/12). Fluent speech frequently occurred as seizure activity was recorded from language-dominant temporal lobe neocortex (6/12 seizures). Of the patients with well-localized seizure onsets who did not speak (6/10), seizures arose from both language-dominant and -nondominant mesial temporal cortex. We conclude that the presence or absence of vocalizations during a seizure does not reliably indicate the anatomic regions in which the seizure begins or spreads.

Adult↗

PubMedDate not supplied

Effect of CO2 inhalation on central sleep apnea and arousals from sleep.

BACKGROUND: CO(2) inhalation reduces central sleep apnea (CSA) in patients with congestive heart failure (CHF) and idiopathic CSA. CO(2) is also a stimulus for cortical arousal, which has been linked to increased sympathetic nerve activity (SNA) and increased mortality in CHF patients with CSA. OBJECTIVE: We have tested the hypothesis that during sleep, inhalation of CO(2) sufficient to reduce the apnea-hypopnea index (AHI) would not reduce the arousal index (AroI). METHODS: In 10 male patients with CSA (7 with CHF and 3 with idiopathic CSA), the inspired CO(2) concentration was increased to raise the sleeping end-tidal CO(2) by 2-4 mm Hg during established stage 2 sleep. Each intervention was maintained for a 10-min period. Sleep stage was monitored with electroencephalograms, electrooculograms, submental electromyogram, airflow with pneumotachometer and respiratory effort and blood gases with oxygen saturation and end-tidal CO(2). During periods of air and CO(2) breathing, AHI and AroI were compared with paired t tests; patients acted as their own controls. RESULTS: Inhalation of CO(2) produced a significant reduction in AHI (mean +/- SEM) from 74.4 +/- 12.4 events/h during air breathing to 25.8 +/- 7.8 events/h with CO(2) inhalation (p = 0.002). However, the AroI was not significantly different between the two conditions, air 67.8 +/- 12.3 events/h and CO(2) inhalation 52.8 +/- 12.4 events/h (p = 0.264). CONCLUSION: CO(2) inhalation reverses CSA but not arousals from sleep. Our findings highlight the need for treatment options that reduce both respiratory events and decrease arousals from sleep, with their associated SNA sequelae.

Administration, Inhalation↗