Enhancement of an inhibitory input to the feeding central pattern generator in Lymnaea stagnalis during conditioned taste-aversion learning

To study the neuronal mechanism of a conditioned taste-aversion (CTA) learning in the pond snail Lymnaea stagnalis, we examined the synaptic connection between the neuron 1 medial (N1M) cell and the cerebral giant cell (CGC), the former is an interneuron in central pattern generator for the feeding response and the latter is a regulatory neuron to the central pattern generator. Inhibitory postsynaptic potential (IPSP) which was evoked in the N1M cell by activation of the CGC was larger and lasted longer in the conditioned animal than that in the control animal. The electrical properties of the cell body of CGC and the responses of the CGC to the chemosensory inputs were not changed during the CTA learning. These results, together with the previous report indicating the existence of excitatory projection from the N1M cell to the feeding motoneuron, suggest that enhanced IPSP in the N1M cell may underlie the suppression of feeding responses in the Lymnaea CTA learning.     

Ehrlich ascites cells activate the alternative pathway of the human complement system

Incubation of Ehrlich ascites cells with normal or C1q or C2 deficient human sera results in killing of the cells. Killing occurred also in the absence of free Ca++, which supported by the fact that factor B and C3 were cleaved, leads to the conclusion that the alternative pathway of the complement system is activated on the surface of the Ehrlich ascites cells.     

Clinical significance of unilateral sinusitis

In general, the etiologic factors of chronic paranasal sinusitis are systemic conditions such as nutrition, predisposition, allergy, and local factors such as nasal anatomic conditions. Among these factors, the development of unilateral sinusitis is a model case verifying the influence of local factors. In my study of 640 cases over a certain period of time, a comparison was made between 161 cases of unilateral sinusitis and 479 cases of bilateral sinusitis in order to verify the effects of local factors in the development of this disease. Patients with a history of previous sinus surgery or tumors were eliminated from the cases. 1. The male-female incidence rate, and the age distribution of the patients at the initial visit showed no prominent differences between unilateral and bilateral cases. 2. It was found that a larger number of cases of unilateral sinusitis had a duration of less than one year as compared to bilateral sinusitis which were longer than and year. Therefore it can be said that the duration of unilateral sinusitis is usually shorter than that of bilateral sinusitis. 3. In unilateral cases the patients with moderate to severe nasal septal deviation, one number of patients with septal deviation towards the diseased side was twice as high as that on the non-affected side. 4. The incidence rate of polyps occurring in the middle meatus was shown to be about twice as high in bilateral cases as in unilateral cases.(ABSTRACT TRUNCATED AT 250 WORDS)     

Identification of neural genes using Xenopus DNA microarrays.

To isolate novel genes regulating neural induction, we used a DNA microarray approach. As neural induction is thought to occur by means of the inhibition of bone morphogenetic protein (BMP) signaling, BMP signaling was inhibited in ectodermal cells by overexpression of a dominant-negative receptor. RNAs were isolated from control animal cap explants and from dominant-negative BMP receptor expressing animal caps and subjected to a microarray experiment using newly generated high-density Xenopus DNA microarray chips representing over 17,000 unigenes. We have identified 77 genes that are induced in animal caps after inhibition of BMP signaling, and all of these genes were subjected to whole-mount in situ hybridization analysis. Thirty-two genes showed specific expression in neural tissues. Of the 32, 14 genes have never been linked to neural induction. Two genes that are highly induced by BMP inhibition are inhibitors of Wnt signaling, suggesting that a key step in neural induction is to produce Wnt antagonists to promote anterior neural plate development. Our current analysis also proves that a microarray approach is useful in identifying novel candidate factors involved in neural induction and patterning.     

Water-soluble treatments to enhance glucose permeability of protein-resistant polymer overlayers

This study employed two water-soluble and nontoxic molecules, sucrose and glycerol, to enhance the permeability of PEG-PHEMA polymer gels coated onto 100 kDa molecular weight cutoff polyethersulfone (PES) microdialysis probes. Sucrose precoating of the probes prior to prepolymer coating prevented penetration of the prepolymer into the microdialysis membrane. Glycerol mixed with the prepolymer introduced porosity in the polymer coating upon curing. The sucrose and glycerol were completely removed by soaking in PBS after curing of the polymer coat on the probe tip. Polymer coated probe glucose permeability was tested by measuring glucose recovery from PBS solutions. Biocompatibility was assessed by measuring glucose recovery of polymer coated probes from heparanized whole porcine blood. Results show that the sucrose and glycerol treatments yielded polymer coated probes with glucose permeability nearly equal to bare probes when tested in PBS solution, but that this increased permeability was not observed when tested in whole blood. This suggests that the thickness of the polymer films (10-100 microm), while not a limiting factor in PBS solution, may have presented a diffusion barrier to glucose recovered from blood. Surprisingly, however, the polymer coated probes exhibited less thrombus formation that did the bare probes after blood exposure.     

Construction and characterization of centric circular and acentric linear chromosomes in fission yeast

Summary Gene disruption and gap repair of chromosomal DNA have been frequently employed techniques in yeast genetics. To extend the possibility of using these gene manipulations for larger genomic regions, we have examined the maximal sizes of chromosomal DNA disrupted or repaired in vivo. Here we report a simple, potentially general, method for selectively deleting a 150 kb region, or gap-filling a 100 kb region, in the fission yeast genome. This enables the generation of acentric linear chromosomes by deletion, or the cloning of large functional centromeric DNAs into circular minichromosomes by gap-filling. The fidelity of the resulting gap-filling is high, judging from partial-digestion mapping of gap-repaired DNAs. By analysing a series of such circular minichromosomes, we conclude that only a part of the repetitive centromeric region, including the central domain, is essential for mitotic and meiotic chromosome segregation. Acentric linear chromosomes, although unstable, could be maintained, indicating that it may be possible to construct an acentric vector for large DNA fragments in this organism.     

Effect of osmotic protection on nucleated cell killing by C5b-9: cell death is not affected by the prevention of cell swelling

Formation of C5b-9 channels in the plasma membrane can lead to erythrocyte lysis or nucleated cell death. Lysis of erythrocytes by complement occurs as a result of colloid osmotic swelling and rupture of the plasma membrane, due to the unregulated flux of ions and water through C5b-9 channels. This colloid osmotic mechanism of lysis is largely based on the evidence that the extent of hemolysis is reduced, when macromolecules are placed in the medium to balance the osmotic gradient created by intracellular macromolecules, which are too large to diffuse through complement channels. The role of colloid osmotic deregulation, as a cause of nucleated cell killing by C5b-9, however, has been recently questioned [Kim S., Carney D. F. and Shin M. L. J. Immun. 138, 1530 (1987)]. In the present study, we investigated the effect of osmotic protection, with an 81,000 mol. wt dextran or bovine serum albumin, on Ehrlich cell killing by complement channels. The results indicated that prevention of cell swelling by dextran did not reduce the extent or rate of nucleated cell killing by either small (C5b-9l), or large (C5b-9m), complement channels when assessed by vital dye stain. The release of cytoplasmic lactate dehydrogenase as an alternative measure of cell death, however, was retarded and/or reduced, in the presence of dextran or albumin, at concns that prevented cell swelling. These results indicate that C5b-9 can kill nucleated cells effectively, in the absence of colloidal osmotic cell swelling, and that release of cytoplasmic macromolecules may not be a reliable indicator of cell death, when osmotic protectants are employed.     

Cloning of a human immunoglobulin gene fragment containing both VH-D and D-JH rearrangements: Implication for VH-D as an intermediate to VH-D-JH formation

In an Epstein-Barr virus-transformed human B cell line we found an unusual immunoglobulin heavy chain gene rearrangement. Restriction mapping and sequencing analysis led us to conclude that V_H-D and D-J_H recombination took place in a single allele. Both V_H-D and D-J_H complexes still had their recombination signal sequences adjacent and the DNA sandwiched by these two complexes retained a germ line configuration, suggesting the potential for a secondary rearrangement resulting in a V_H-D(-D)-J_H formation. With this finding, we propose a novel pathway, in which the V_H-D complex is an intermediate in the formation of a functional V_H exon.     

Isometric and isokinetic torque curves at the knee joint

Isometric and isokinetic torques of bilateral quadriceps and hamstrings were measured with Isokinetic Rehabilitation and Testing System (Model No. Cybex 340) on 40 normal untrained subjects, 20 males and 20 females, ranging between the ages of 23 and 35 years. The mean peak isometric and isokinetic torque values of both muscle groups showed no significant differences between dominant (right) and nondominant (left) limbs in both sexes; however there were significant differences between the male and the female. As the angular velocity increased, the peak torque significantly decreased, and the point of peak torque output occurred significantly later in the range of motion for quadriceps and hamstrings (p less than 0.01). There were no significant changes in the hamstrings to quadriceps (H/Q) ratios as the angular velocity increased. However, there were significant differences of mean H/Q ratio between male and female (p less than 0.01). Height had significant positive correlation with peak isometric and isokinetic torques for both quadriceps and hamstrings (p less than 0.01). Weight was found to correlate significantly with peak isometric and isokinetic torques (p less than 0.01). The mean isometric torques were significantly higher than the mean isokinetic torques for any joint angles in both sexes (p less than .01).