Biomedical subjects
Publications and source records attributed to R F Jansen.
A PC-based method for the reconstruction of individual spike trains from extracellular multineuron recordings is described. Starting with virtually no knowledge about the wave forms in a record, a fully automatic template-finding algorithm extracts templates using the entire data set. In a second step, individual spike trains are reconstructed.
A method for the reconstruction of the individual spike trains from extracellular multineuron recordings is described. A neural network emulation program is trained to recognize a sample set of digitized spikes. The digitized spikes are fed into the neural network, and the network output is used to classify spikes in terms of the training set. The system runs on any PC and its speed makes is especially well suited for the analysis of large amounts of data.
A total of 144 evaluable patients with breast cancer were enrolled in a multicenter, randomized, prospective study to establish the role of delayed shoulder exercises on wound drainage and shoulder function after axillary lymph node dissection. Patients in group 1 (n = 78) started active shoulder exercises 1 day postoperatively. Patients in group 2 (n = 66) started on the eight postoperative day, following 1 week of immobilization of the arm. Patients in group 2 had 14% less wound drainage volume than those in group 1 (600 +/- 436 mL versus 701 +/- 398 mL); this difference, however, was not significant. Also, no differences could be established between the two groups when duration and volume of wound drainage, number and volume of seroma aspirations, wound complication rates, and shoulder function were compared 6 months after surgery.
A 61-year-old man with an intractible and progressively disabling cutaneous non-Hodgkin's lymphoma (NHL) in the lower limb was treated with sequential regional isolated perfusion at 10-day intervals. The first perfusion was hyperthermic (40.2-43.1 degrees C tumor-temperature); the second was at controlled normothermia with high-dose 1-phenylalanine mustard (melphalan, L-Pam; 11 mg/l perfused tissue). This treatment resulted in a complete remission in the perfused area of significant duration and has prevented amputation.
Hyperthermic perfusion was given as a palliative treatment in three patients with a bulky tumour in the leg. During the treatment, temperature and pH data were collected in both tumour and normal tissues. The hyperthermia dose administered was 2 h at 41.9-42.7 degrees C. It was found that the temperature distribution was far from homogeneous. In one case tumour pH could be monitored throughout the whole treatment procedure. The tumour pH showed a steep decrease during the initial phase of the perfusion, from a mean value of 7.11 to 5.94 at the start of the hyperthermic phase. Subcutis pH decreased only 0.29 units during the whole procedure. In all three patients considerable tumour regression was observed, without severe toxicity. Hyperthermic perfusion appeared to be an effective debulking treatment. The pH decrease in tumour tissue, immediately before hyperthermia, may be responsible for the remarkable effectiveness of the hyperthermic treatment.
The bag cell neurons of the abdominal ganglion of Aplysia are a useful system for the study of peptidergic neurotransmission. A 20 min burst of impulse activity in the bag cells induces or augments repetitive firing in LB and LC neurons in the abdominal ganglion for up to several hours. Previous experiments have indicated that this effect is mediated by the putative bag cell transmitter egg-laying hormone (ELH). Using voltage-clamp analysis we found that bag cell bursts (BCBs) evoke long-lasting changes in membrane current in these neurons that are mimicked by the application of ELH. The combined ELH-evoked current is inward at all membrane potentials between -110 and -10 mV and consists of 3 separable currents persisting for 30-120 min. They include (1) a depolarizing current that is activated at membrane potentials above -40 mV. This current, termed ISI, is blocked by prolonged exposure to 10 mM Ni2+/0 mM Ca2+ and is not abolished by 0 mM Na+ or 100 mM TEA+/0 mM Na+ in the bathing medium. It is therefore a Ca2+-sensitive current and does not involve Na+ as a charge carrier. (2) There is a hyperpolarizing current that is activated at membrane potentials below approximately -70 mV. This current, termed IR, is blocked by external Rb+ (5 mM) and Cs+ (10 mM) and has a chord-conductance that shifts with the external [K+] according to the Nernst potential for potassium. It is therefore an inwardly rectifying K+ current. (3) There is a small, steady depolarizing current, termed Ix. This current is the only one that remains after prolonged exposure to 10 mM Ni2+/0 mM Ca2+-containing bathing medium. It is Na+ dependent and is associated with a small increase in membrane conductance that is largely independent of membrane voltage. All 3 currents are slow to inactivate; they appear to sum algebraically to produce the net BCB- or ELH-evoked current.
Egg-laying in Lymnaea is characterized by the stereotyped egg-laying behavior (ELB), composed of foot contractions and shell movements. Egg-laying can be induced by a clean water stimulus, that triggers a discharge of the neuroendocrine caudo-dorsal cells (CDCs), which release the ovulation hormone into the blood. A part of the behavior is lost when egg-laying is triggered by hormone injection, indicating that during natural stimulus-induced or spontaneous egg-laying this part (the first phase) may be controlled by neuronal events in the CNS triggered by (a) factor(s) not released to the blood. The authors have identified an unpaired neuron, the ring neuron, that is excited during an in vitro afterdischarge of the CDCs, and which, by its numerous axonal branches in the pedal ganglia, modulates motorneurons of the columellar muscle, which controls shell movements. These motor-neurons, identified as such in reduced preparations by 1 for 1 muscle potentials and elements in the connecting nerve, all receive either excitatory or inhibitory input from the ring neuron, as well as from an unknown neuron which has common input of the ring neuron and the motorneurons. The action of the CDCs on the ring neuron cannot be mimicked by the ovulation hormone, and we therefore conclude that the first part of the ELB is probably caused by a nonhormonal local action of the CDCs on the ring neuron and possibly the common input neuron.
Ovulation in the pond snail Lymnaea stagnalis is controlled by the neuroendocrine caudo-dorsal cells (CDCs) in the cerebral ganglia, which release an ovulation hormone during a period of impulse activity. Firing of the single RN in the right cerebral ganglion hyperpolarizes the CDCs. This hyperpolarization is caused by the opening of potassium channels in the axons that connect both the CDC clusters. By this action, that presumably is mediated by axonal branches of the RN in the intercerebral commissure closely associated with these CDC axons, the RN decouples both the CDC clusters. Although the RN has negative feedback on the CDC, it does not control afterdischarge characteristics. The authors suggest that the RN, next to the egg-laying behavior, is involved in another behavior, not compatible with ovulation. Male reproductive activity is presented as a possible candidate for such behavior.
One hundred and twenty-three dual lumen silicone rubber central venous catheters were inserted into 101 patients with hematological malignancies undergoing intensive treatment. There was a perioperative complication rate of 13%. Open and closed techniques for inserting the catheter were compared. The operating time needed for introducing the catheter by the closed technique (average, 51 minutes) was significantly shorter (p less than 0.001) than the time needed for the open technique (70 minutes), whereas complication rates were equal in both techniques. On average, the catheters functioned for 149 days. Complications leading to removal were observed in 29.3% of patients, most of which were catheter-related infections (20.4%). Thromboembolic complications leading to removal were less frequent (4.1%) and appeared significantly earlier (p less than 0.001). These data indicate that introduction of the catheter by direct puncture of the subclavian vein is a quick and safe technique, and that this type of catheter is suitable for long-term use, both for infusion and for blood sampling.