Search PubMed⌕ Search

Biomedical subjects

K Wise

Publications and source records attributed to K Wise.

28 records · Page 2Linked to original sources
PubMed1995

Gamma (40-100 Hz) oscillation in the hippocampus of the behaving rat.

The cellular generation and spatial distribution of gamma frequency (40-100 Hz) activity was examined in the hippocampus of the awake rat. Field potentials and unit activity were recorded by multiple site silicon probes (5- and 16-site shanks) and wire electrode arrays. Gamma waves were highly coherent along the long axis of the dentate hilus, but average coherence decreased rapidly in the CA3 and CA1 directions. Analysis of short epochs revealed large fluctuations in coherence values between the dentate and CA1 gamma waves. Current source density analysis revealed large sinks and sources in the dentate gyrus with spatial distribution similar to the dipoles evoked by stimulation of the perforant path. The frequency changes of gamma and theta waves positively correlated (40-100 Hz and 5-10 Hz, respectively). Putative interneurons in the dentate gyrus discharged at gamma frequency and were phase-locked to the ascending part of the gamma waves recorded from the hilus. Following bilateral lesion of the entorhinal cortex the power and frequency of hilar gamma activity significantly decreased or disappeared. Instead, a large amplitude but slower gamma pattern (25-50 Hz) emerged in the CA3-CA1 network. We suggest that gamma oscillation emerges from an interaction between intrinsic oscillatory properties of interneurons and the network properties of the dentate gyrus. We also hypothesize that under physiological conditions the hilar gamma oscillation may be entrained by the entorhinal rhythm and that gamma oscillation in the CA3-CA1 circuitry is suppressed by either the hilar region or the entorhinal cortex.

Animals↗
PubMed1993

Dose-related efficacy and bleeding complications of double-chain tissue plasminogen activator in acute myocardial infarction. The Wellcome Tissue Plasminogen Activator Study Group.

Although the efficacy of recombinant tissue-type plasminogen activator (rt-PA) in acute myocardial infarction has been demonstrated, little formal dose-ranging information is available. This study examined the use of duteplase, the double-chain rt-PA subsequently used in the Third International Study of Infarct Survival, in a multicenter trial of 267 patients with evolving acute myocardial infarction assigned to receive 1 of 6 weight-adjusted doses. The primary end point was infarct vessel patency after 90 minutes of drug infusion. Patency was defined as Thrombolysis in Myocardial Infarction trial grade 2 or 3 perfusion, and was determined by an independent core laboratory masked to treatment assignment. Patency was present in 48% of patients receiving the lowest dose range and 78% of those receiving the highest, with an association between thrombolytic dose and patency (p = 0.009). The frequency of serious bleeding complications also correlated with the total dose of rt-PA infused (p = 0.003). Bleeding complications were primarily related to instrumentation; blood loss requiring transfusion or otherwise deemed clinically significant occurred in 12% of patients (central nervous system hemorrhage occurred in 1.1%). Thus, higher doses of rt-PA are associated both with increased efficacy and increased risk of serious bleeding complications. Weight-adjusted dosing may provide an optimal risk-benefit ratio for thrombolysis during acute myocardial infarction.

Adult↗
PubMed1992

High-frequency network oscillation in the hippocampus.

Pyramidal cells in the CA1 hippocampal region displayed transient network oscillations (200 hertz) during behavioral immobility, consummatory behaviors, and slow-wave sleep. Simultaneous, multisite recordings revealed temporal and spatial coherence of neuronal activity during population oscillations. Participating pyramidal cells discharged at a rate lower than the frequency of the population oscillation, and their action potentials were phase locked to the negative phase of the simultaneously recorded oscillatory field potentials. In contrast, interneurons discharged at population frequency during the field oscillations. Thus, synchronous output of cooperating CA1 pyramidal cells may serve to induce synaptic enhancement in target structures of the hippocampus.

Action Potentials↗
PubMed1990

Prophylaxis against postsplenectomy pneumococcal infection.

An excess risk of overwhelming sepsis following splenectomy is well established. In view of this, surgical responsibility must embrace the administration of pneumococcal prophylaxis. Current recommendations vary, but routine pneumococcal vaccination, together with penicillin prophylaxis in selected patients, is advocated widely. This retrospective review of 75 patients undergoing splenectomy was undertaken in order to evaluate the extent to which current practice complies with these recommendations. Among surviving patients, the incidence of vaccination with polyvalent pneumococcal vaccine (PPV) was found to vary according to operative indication. All haematological patients received pre-operative PPV. Two-thirds of multitrauma patients were vaccinated, while 42% of patients who required splenectomy following accidental intra-operative trauma received PPV. Only 11% of patients who underwent incidental splenectomy were vaccinated. Long-term antibiotic prophylaxis was commenced in 33% of surviving patients under 20 years of age, and in 8% with underlying malignancy. These results highlight a need for greater vigilance in the administration of pneumococcal prophylaxis, particularly following accidental or incidental splenectomy.

Adult↗
PubMed1985

Pharmacokinetic study of ceftazidime in bone and serum of patients undergoing hip and knee arthroplasty.

Twenty-eight patients undergoing hip arthroplasty and 15 undergoing knee arthroplasty, received chemoprophylaxis with ceftazidime 1.0 g administered intravenously at the time of induction of anaesthesia, followed by two doses of 500 mg given intramuscularly 6 and 12 h later. The mean bone concentration in hip arthroplasty showed a general rise towards a maximum of approximately 20 mg/kg when the exposure time (interval between antibiotic injection and removal of bone sample) was 35-40 min, with values ranging from 4.4 to 21.2 mg/kg (mean 14.4 mg/kg). The patients undergoing knee arthroplasty present a complicated pharmacokinetic problem, as the use of a tourniquet limits the exposure time. Bone concentrations of ceftazidime were highest at sampling times greater than 20 min in these patients (mean level of 15.9 mg/kg for femoral bone and 13.1 mg/kg for tibial bone).

Adult↗
PubMed1984

Role of the lemon in disseminated candidiasis of heroin abusers.

The occurrence of several small outbreaks of disseminated candidiasis among heroin abusers in Australia suggests that a common source for infection was present in each incident. Because in all outbreaks so far described lemon juice has been used to dissolve heroin powder before injection, we decided to examine the ability of lemon juice to support the growth of Candida albicans. Lemons which were experimentally inoculated with small numbers of C. albicans promoted the rapid growth of the organism at room temperature. We propose that clinical infection results from the intravenous injection of a large inoculum of C. albicans from contaminated lemon juice. This is supported by the simultaneous occurrence of the disease in three drug abusers. We also propose that the lemon was contaminated by the heroin abusers, as disseminated candidiasis occurred only after the lemon was used a second time after being left at room temperature for one week.

Adult↗
PubMed1979

A correlation of the surgical and radiculographic findings in lumbar disc herniation.

The findings on plain radiographs and at water-soluble radiculography are compared with those at laminectomy in 50 patients with lumbar disc protrusions. Predictions of the level of disc protrusion based on the plain radiographic appearances could be made in 71%. Water-soluble radiculography accurately demonstrated 50 of 52 protrusions (96%). No abnormality was found at surgery at three other disc levels where equivocal radiculographic appearances failed to eliminate the possibility of disc protrusion. When all the levels examined surgically are included the water-soluble radiculogram was accurate at 57 levels out of 62 (92%). The immediate morbidity of radiculography is described and significant side effects were shown by 23% of patients.

Adult↗
PubMedDate not supplied

Neurologic assessment of the multiple trauma patient.

Assessment and documentation of neurologic deficits are critical for prompt intervention to correct or prevent the deficit. The ability to identify signs and symptoms of neurologic deficit which may be life threatening or permanently disabling is an important component of nursing assessment for multiple trauma patients.

Glasgow Coma Scale↗