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Biomedical subjects

R Wennberg

Publications and source records attributed to R Wennberg.

34 records · Page 2Linked to original sources
PubMed1999

Type III intermittency in human partial epilepsy.

A rigorous characterization of the dynamic regimes underlying human seizures is needed to understand, and possibly control, the transition to seizure. Intra- or extracranial brain electrical activity was recorded in five patients with partial epilepsy, and the interictal and ictal activity analysed to determine the dynamics of seizures. We constructed first-return one-dimensional maps by fitting the scatter plots of interpeak intervals. The features of the mapping indicated that type III intermittency is the dynamic characteristic of the ictal events. This was confirmed using histograms of the durations of the regular phases during seizures. The intermittent regime explains the abrupt transitions observed during ictal events in terms of transient stabilization of the unstable steady state.

Brain↗
PubMed1999

Intraoperative localization of an epileptogenic focus with alfentanil and fentanyl.

UNLABELLED: We evaluated the effectiveness of alfentanil and fentanyl in stimulating epileptogenic activity during surgery for intractable temporal lobe epilepsy under general anesthesia. Ten patients received a standardized anesthetic induction with i.v. fentanyl 5 microg/kg, propofol 3-5 mg/kg, and atracurium 0.5 mg/kg. Maintenance was with isoflurane, 70% N2O/30% O2, and an atracurium infusion. After dural opening, droperidol 0.02 mg/kg was administered i.v.. Both inhaled anesthetics were discontinued and verified to be at 0 end-tidal concentration before the study. Baseline electrocorticography over the surface of the temporal lobe and depth electrode recordings in the amygdala and hippocampus were obtained, followed by 10 min of recording before and after the i.v. administration of both alfentanil 50 microg/kg and fentanyl 10 microg/kg. Any changes in cardiovascular variables were documented. The number of interictal epileptiform spikes at the most active site for each patient was tabulated before and after the administration of each drug. Both alfentanil and fentanyl induced an increase in spike activity in all patients. Alfentanil was more potent, increasing the median number of spikes per epoch from 18 to 58, compared with fentanyl (20 to 42 spikes) (P < 0.05). Alfentanil had a shorter duration of action (4.9+/-1.3 min) compared with fentanyl (8.5+/-2 min) (P < 0.009). In nine patients, the most active site was the hippocampus or amygdala. There was a decrease in mean blood pressure, but only after the administration of alfentanil (P < 0.05). Two patients had electrographic evidence of seizure activity. These opioids can be used to assist in the localization of the epileptogenic focus during surgery. IMPLICATIONS: Both alfentanil and fentanyl activate epileptiform activity in patients with temporal lobe epilepsy. These opioids can be used to assist in the localization of the epileptogenic focus during surgery.

Adult↗
PubMed1999

Role of electrocorticography at surgery for lesion-related frontal lobe epilepsy.

BACKGROUND: The prognostic significance of epileptiform activity (EA) recorded intraoperatively at electrocorticography (ECOG) in patients with lesion-related frontal lobe epilepsy (FLE) is unknown. METHODS: The results of ECOG performed in 22 patients with intractable FLE and a circumscribed frontal lobe structural lesion were compared with postoperative seizure control. Three patients underwent re-operation for a total of 25 cases, 23/25 with post-resection ECOG. Lesions were neoplasms (12), hamartomas (6) and arteriovenous malformations (4). RESULTS: Outcomes were 15/25 Class I, 5/25 Class III and 5/25 Class IV (Engel classification). Class I outcome was associated with pre-excision EA recorded from < or = 2 gyri (p < 0.05) and absence of EA, or EA limited to the resection border, at post-excision ECOG (p < 0.01). Complete lesion excision was highly correlated with Class I outcome (p < 0.001). The most significant correlations were seen when ECOG and lesionectomy variables were considered together: all 12 cases with complete lesionectomy and absent post-excision EA distant to the resection border had Class I outcome (p < 0.00015) and all 13 cases with complete lesionectomy and pre-excision EA recorded from < or = 2 gyri had Class I outcome (p < 0.00005). CONCLUSIONS: Postoperative seizure control in lesion-related FLE is assured in the setting of complete lesion resection with pre-excision EA recorded from < or 2 gyri and no post-excision EA distant to the resection border; complete lesion excision is of paramount importance.

Adolescent↗
PubMed1999

A genetic and molecular characterization of the garnet gene of Drosophila melanogaster.

The garnet gene was one of the first genes to be identified in Drosophila melanogaster. Mutations in the garnet gene affect both of the biochemically distinct types of pigments in the eye and disrupt pigmentation of other organs. As an initial step in the analysis of this gene, we have analyzed the pigmentation defects in several of the garnet alleles. We have also cloned the gene and examined its expression in various tissues and at different stages of development. The garnet gene is expressed throughout development and in all tissues examined. Structurally related sequences can be detected in a variety of other eukaryotes. The predicted protein sequence of the garnet product resembles clathrin and nonclathrin adaptin proteins and is highly similar to the delta subunit of the newly isolated mammalian AP-3 adaptin complex, which is associated with the trans-Golgi network and endosomes. This suggests that garnet encodes a protein that acts in the intracellular sorting and trafficking of vesicles from the trans-Golgi network to endosomes, and related specialized organelles such as the pigment granule. This finding provides an explanation for the phenotype of garnet mutations and predicts that other Drosophila eye-colour genes will be a rich resource for the genetic dissection of intracellular vesicle transport.

Adaptor Protein Complex 3↗
PubMed1998

Electrocorticography and outcome in frontal lobe epilepsy.

The prognostic significance of epileptiform activity (EA) recorded at electrocorticography (ECOG) was examined in a group of 60 consecutive non-tumoral patients with intractable frontal lobe epilepsy (FLE). Pre-excision EA was documented as absent, focal (one gyrus), regional (two gyri), lobar (3 gyri) or multilobar (frontal + temporal gyri). Post-excision EA was documented as absent, restricted to the resection border, or recorded distant to the resection border, and was quantitated by spike frequency. Pre-excision EA from < or = 2 gyri and absence of post-resection EA correlated with Class I or II (Engel classification) outcome while pre-excision EA from > or = 3 gyri and persistent post-resection EA, especially distant to the resection border, correlated with Class III or IV outcome (P < 0.001). A significant correlation between poorer outcomes and increased abundance of distant post-resection EA was observed (P < 0.001). EA restricted to the resection border was not significantly correlated with outcome. Presence of a circumscribed lesion correlated with Class I outcome (P < 0.01) and absence of pathological abnormality correlated with Class IV outcome (P < 0.05). Neither side nor extent of surgical excision correlated with outcome. EA recorded at ECOG is of prognostic significance in FLE. A lobar or multilobar distribution of pre-excision EA and persistent post-excision EA distant to the resection border, especially when abundant, are highly unfavorable prognostic indicators. In contrast, a restricted distribution of pre-excision EA and absence of post-resection EA both herald a favorable outcome.

Adolescent↗
PubMed1998

Multiple actions of methohexital on hippocampal CA1 and cortical neurons of rat brain slices.

To explore the mechanism by which methohexital (MTH) activates epileptiform activity in patients with epilepsy, we examined the effects of MTH on hippocampal CA1 and neocortical neurons via extracellular and whole-cell patch-clamp recordings in rat brain slices. Perfusion of slices with 10 to 100 microM MTH caused no significant change in glutamatergic transmission in the hippocampal CA1 region, but enhanced gamma-aminobutyric acid (GABA)A-mediated inhibitory postsynaptic currents and induced spontaneous inhibitory postsynaptic currents in neocortical and hippocampal CA1 neurons. In addition, MTH induced a tonic, bicuculline-sensitive hyperpolarization in association with increases in membrane conductance, suggesting a direct stimulation of GABAA receptors by MTH. Spontaneous epileptiform activity was not observed in the neocortex and hippocampus after exposure of slices to MTH, neither in the standard in vitro condition nor in the presence of 4-aminopyridine, which promotes rhythmic synaptic activities. We suggest that the activation of epileptiform activity in vivo by MTH may result from increased neuronal synchrony via the potentiation of GABAA-mediated synaptic inhibition.

4-Aminopyridine↗
PubMed1997

Mesial temporal versus lateral temporal interictal epileptiform activity: comparison of chronic and acute intracranial recordings.

Intracranial interictal epileptiform activity (EA) was recorded by chronic stereotactic depth electroencephalography (SDEEG) and acute electrocorticography (ECOG) in 22 patients with complex partial seizures of temporal lobe origin. Chronic SDEEG recordings defined two groups of patients with respect to the presence or absence of lateral temporal EA; 13 patients showed independent lateral temporal EA during chronic recordings and 9 patients did not. All patients had EA recorded from mesial temporal structures during SDEEG. The presence of lateral temporal EA was correlated with a higher pre-operative seizure frequency but not with ictal onset zones, structural pathology, age at onset of epilepsy, or duration of epilepsy. Results of acute ECOG recordings performed on the same patients 1-24 months after SDEEG accurately reproduced the mesial versus lateral distribution of EA within patients (P < 0.0003). Though ECOG was less sensitive than SDEEG in demonstrating EA confined to mesial structures, positive findings at ECOG were 100% specific with respect to SDEEG. These results suggest that, at least with respect to mesial temporal versus lateral temporal structures, there is a constancy within patients in the distribution of interictal EA recorded with chronic intracranial electrodes. In addition, acute ECOG provides an accurate representation of individual patients' interictal EA.

Adult↗
PubMed1997

Induction of burst-suppression and activation of epileptiform activity after methohexital and selective amygdalo-hippocampectomy.

Electrocorticography (ECOG) compared the effects of methohexital (MTH) and selective amygdalo-hippocampectomy (selAH) upon lateral temporal neocortical epileptiform activity (EA) in 31 patients with mesial temporal epilepsy. Pre-excision ECOG showed independent neocortical EA before MTH in 12/31 and after MTH in 18/31. MTH (20-50 mg) activated neocortical EA in 12 cases and induced burst-suppression (BS) over temporal neocortex in 14/31. Post-excision ECOG showed neocortical EA in 21/31 and BS in 27/31: compared with pre-excision ECOG before MTH, selAH activated neocortical EA in 15 cases. Significant correlations were found between presence of pre-excisional neocortical EA and presence of post-excisional neocortical EA (P < 0.001) and between activation of pre-excisional neocortical EA by MTH and activation of (post-excisional) neocortical EA by selAH (P < 0.006). Presence or severity of BS in the post-excision ECOG was not correlated with presence, absence or activation of post-excisional EA. Presence of neocortical EA was significantly correlated with a higher pre-operative seizure frequency (P < 0.001) but not with duration of epilepsy nor surgical outcome. Both MTH and selAH can induce neocortical BS, likely through chemical and surgical disconnection of cortex, respectively. Unrelated to induction of BS, MTH and selAH appear to decrease threshold for expression of neocortical EA in a similar fashion.

Adolescent↗
PubMed1982

Group B streptococcal lung infection in neonatal rabbits.

The interaction of alveolar macrophages (AMs) and group B streptococci (GBS) was investigated in 1 and 2-day-old rabbits following infection in an exposure chamber containing 10(7) streptococci per cubic foot of air. The % of streptococci within AMs was similar at 0 and 4 h (36 and 65%) after infection for the two groups of rabbits. Twenty-four h after infection, the 2-day-old rabbits had a significantly higher % of ingested GBS (86 versus 68%). Sixty % of inspired GBS were inactivated by the older rabbits within 4 h after infection. This clearance persisted in the younger rabbits until 48 h (mean negative clearance of -17, -276, and -79% at 4, 24, and 48 h) before their numbers were reduced by inflammation. Sixty of 78 1-day-old rabbits had inflammatory responses between 24 and 72 h versus only 5 of 50 older rabbits. At 24 h after infection, AMs of 1-day-old rabbits contained significantly increased numbers of intracellular GBS microcolonies (17/20) than did AMs from 2-day-old rabbits (5/19). These observations suggest that the enhanced susceptibility to GBS infection in the immediate postnatal period is caused at least in part by ineffective intracellular killing by AMs.

Age Factors↗
PubMed1977

Neonatal lung defense mechanisms: a study of the alveolar macrophage system in neonatal rabbits.

Abnormal function of the alveolar macrophage system may explain the enhanced susceptibility to pulmonary infection in human neonates. This hypothesis was investigated by infecting 1- to 14-day-old rabbits with aerosols of Staphylococcus aureus and then measuring in situ rates of bacterial ingestion, inactivation, and destruction in the lapine lung. The inhaled staphylococci were killed within the lungs of 1-day-old rabbits at a significantly slower rate than that for 7- and 14-day-old rabbits (P less than 0.05). Much of this decrease was due to diminished rates of bacterial ingestion by alveolar macrophages of younger animals. Staphylococci were also killed and destroyed less rapidly within these macrophages, but these differences could not be tested for significance.

Animals↗
PubMedDate not supplied

Effects of the acute care nurse practitioner role on epilepsy monitoring outcomes.

This study demonstrated the effectiveness of the implementation of the Acute Care Nurse Practitioner (ACNP) role in the management of patients with seizure disorders in an Epilepsy Monitoring Unit. Findings indicated that the ACNP, functioning in an expanded role in the epilepsy program, can make a substantial contribution to organizational outcomes. This is achieved through patient satisfaction and reduction in the number of laboratory tests performed, hospital length of stay, and overall costs.

Acute Disease↗