PubMed Health⌕ Search

Biomedical subjects

S Kayama

Publications and source records attributed to S Kayama.

11 recordsLinked to original sources
PubMed2000

Overgrowth and translocation of Escherichia coli from intestine during prolonged enteral feeding in rats.

Our objective was to examine changes in bacterial flora in the gastrointestinal tract that might lead to their translocation during the prolonged enteral administration of an elemental liquid diet. Eleven rats (experimental group) received a feeding gastrostomy and were administered an intragastric infusion of a liquid elemental diet for 17 days, while 9 rats (control group) received chow and water ad libitum for 17 days. The animals were then killed and the mesenteric lymph nodes (MLNs), liver, jejunum, ileum, and cecum were aseptically removed, homogenized, and cultured for isolation of bacteria. A statistically significant increase in the population of a single species of Enterobacteriaceae, Escherichia coli, was observed in the ileum and cecum of the experimental group fed the liquid diet as compared with the control group. Five of the MLNs from the 11 experimental rats (45%) were positive for E. coli, as compared with none from the 9 control rats, a statistically significant difference (P = 0.038). The E. coli isolated from the MLNs and the ileum of the experimental group exhibited the O168:H serotype. Our results suggest that E. coli isolated from the MLNs of the experimental group had translocated from the intestine. The animal model described here may be useful in screening for drugs to reduce the problem of translocation of intestinal bacteria.

Animals↗
PubMed2000

Nucleus pulposus inhibits the axonal outgrowth of cultured dorsal root ganglion cells.

Although it is well established that nucleus pulposus cells may induce structural and functional changes in adjacent nerve roots when placed epidurally, it is not known whether this is due to direct neurotoxic effects or whether the nerve roots are affected indirectly by reduction of nutrition and inflammatory/immunologic mechanisms. In the present study we assessed the effects of various tissues on cultured dorsal root ganglions from newborn rats. Nucleus pulposus was found to have a toxic effect on the axons by blocking axonal outgrowth, but no similar effects on the nerve cell bodies (extra-ganglionic nerve cell density, nerve cell arborisation) were found as compared to the series with only culture medium. Sterile water for 1 or 24 h (positive controls) induced significant effects by all four criteria, whereas medium without nerve growth factor, fat and frozen nucleus pulposus had no statistically significant effects. The study thus showed that there are direct axonotoxic effects induced by the nucleus pulposus, and since frozen nucleus pulposus did not have any effects, it may be assumed that the mechanisms are related to substances produced by the nucleus pulposus cells. The presented model allows for future studies on the neurotoxic properties of nucleus pulposus cell-derived candidate substances.

Animals↗
PubMed1998

Cultured, autologous nucleus pulposus cells induce functional changes in spinal nerve roots.

STUDY DESIGN: Nerve conduction velocity in pig nerve roots was assessed after application of various preparations of nucleus pulposus and control. OBJECTIVE: To study whether cultured nucleus pulposus cells could reduce nerve conduction velocity after epidural application. SUMMARY OF BACKGROUND DATA: It is known that nucleus pulposus applied epidurally may reduce the nerve conduction velocity of the adjacent nerve roots and that this reduction seems to be related to the cells of the nucleus pulposus. METHODS: Nucleus pulposus cells and fibroblasts were cultured for 3 weeks, and various preparations were applied to the cauda equina in 29 pigs. The cells were always from the same animals from which they had been harvested. After 1 week, nerve conduction velocity was determined by local electrical stimulation. RESULTS: Application of live fibroblasts and conditioned culture medium from the nucleus pulposus cell culture dishes did not induce significant reduction of conduction velocity, compared with application of dead fibroblasts, which served as control. However, application of live and dead nucleus pulposus cells induced significant reductions. CONCLUSIONS: Application of nucleus pulposus cells reproduced the previously seen reduction in nerve conduction velocity induced by nonmodified nucleus pulposus. Because membranes of the nucleus pulposus cells had similar effects, it can be assumed that the effects are related to membrane-bound substances or structures.

Animals↗
PubMed1996

Incision of the anulus fibrosus induces nerve root morphologic, vascular, and functional changes. An experimental study.

STUDY DESIGN: The effects on nerve root structure, vasculature, and function after incision of the adjacent disc was studied in a dog model. OBJECTIVES: To see if only incision of the disc per se is sufficient for inducing similar changes. SUMMARY OF BACKGROUND DATA: It is well known that nucleus pulposus will induce nerve root structural and functional changes in experimental situations. In these previous studies, relatively large amounts of nucleus pulposus were applied. METHODS: The left L7 nerve root was exposed and mobilized in 10 dogs. In five dogs, the adjacent L6-L7 disc was incised, and in five other dogs, the disc was not incised. After 7 days, nerve conduction velocity was recorded, and specimens were obtained for histologic evaluation. RESULTS: The nerve conduction velocity was significantly lower in the incision group (13 +/- 14 m/sec) compared with the nonincision group (73 +/- 5 m/sec). Structural changes of the axons were more pronounced in the incision group, however, the degree and distribution was too limited to fully account for the neurophysiologic reactions observed. There aims were obvious signs of capillary stasis with an increased number and diameter of the intraneural capillaries in the incision group. CONCLUSIONS: The present study indicated that incision of the anulus fibrosus is sufficient to induce significant morphologic and functional changes and that vascular mechanisms may be of importance for the observed changes. These experimental data suggest that leakage of nucleus pulposus material from anular tears, with injury to adjacent nerve roots, might be one pathophysiologic mechanism in patients with low back pain and sciatica but with no radiologic or surgical evidence of disc herniation.

Animals↗
PubMed1996

Increased resistance to acute compression injury in chronically compressed spinal nerve roots. An experimental study.

STUDY DESIGN: Nerve conduction velocity was studied in the dog cauda equina subjected to chronic and, 1 week later, additional acute compression. OBJECTIVES: To model the situation of spinal stenosis by first inducing a controlled, chronic compression injury and then to add compression at various pressure levels to the already compressed cauda equina. SUMMARY OF BACKGROUND DATA: Previous models on nerve root and cauda equina compression have analyzed the effects of compression only on noninjured nerves. Clinically, the nerves that are compressed in spinal stenosis already are exposed to chronic compression. METHODS: The cauda equine in the lumbar spine of 10 dogs was first compressed by inflating a plastic balloon, which was placed in the spinal canal, to 10 mm Hg with a viscous substance or leaving it noninflated for control. After 1 week, a second plastic balloon, which was welded together with the first balloon, which had been located in the spinal canal for 1 week, was inflated to 50 or 100 mm Hg for 2 hours with 1.5 hour of recovery, and changes in the nerve conduction velocity were analyzed. Before inflation, baseline data, reflecting the effects of the chronic compression per se, were obtained. RESULTS: After 1 week, the nerve conduction velocity was significantly lower in the compressed cauda equina than in the control series, as an effect of the chronic compression. Additional compression demonstrated that the chronically compressed cauda equina was less susceptible to the compression-induced effects at 100 mm Hg compression. CONCLUSIONS: The data of the present study indicate that chronically compressed nerve roots acquire a tolerance to acute compression, which may indicate that there has been adaptation processes present in the compressed nerve tissue.

Acute Disease↗
PubMed1996

Effects of OP-1206 (prostaglandin E1) on nerve-conduction velocity in the dog cauda equina subjected to acute experimental compression.

The effect of OP-1206, a prostaglandin E1 derivative, on cauda equina function was analyzed in a model for acute cauda equina compression in the dog. An inflatable balloon was placed under the lamina of the seventh lumbar vertebra in the dog and muscle action potential area (MAP area) and nerve-conduction velocity (NCV) were monitored during 2 h of compression and 1.5 h of recovery. OP-1206 was infused systemically at three concentrations. Only the highest concentration (30 ng/kg/min) of OP-1206 could prevent the reduction in NCV. However, this concentration had no similar effect on the MAP area. The data suggest the potential therapeutic use of prostaglandin E1 analogues for the future treatment of intermittent claudication.

Action Potentials↗
PubMed1993

Intramedullary spinal cord sarcoidosis. Report of two cases.

Two cases of intramedullary spinal cord sarcoidosis are reported. These lesions could not be differentiated from neoplastic spinal cord tumors by clinical findings or imaging studies. In magnetic resonance imaging, the lesions were enhanced around the gray matter with gadlinium diethylene triamine pentaacetic acid (Gd-DTPA). The true diagnosis was established only by histologic examination of the surgical specimen. The possibility of intramedullary sarcoidosis presenting as a tumor should be included in the differential diagnosis of mass lesions of the spinal cord.

Aged↗
PubMed1993

Resting energy expenditure in patients undergoing transhiatal or transthoracic oesophagectomy for carcinoma of the thoracic oesophagus.

Resting energy expenditure (REE) was studied in five patients undergoing transhiatal and in 14 undergoing transthoracic oesophagectomy for carcinoma. All resections were performed with an intention to cure. REE was measured by indirect calorimetry before operation and on days 1, 3, 5 and 7 after surgery. Following transthoracic oesophagectomy, REE increased significantly on days 1, 3, 5 and 7 after operation, and on day 7 the value was significantly higher (P < 0.05) than that obtained after transhiatal surgery. Energy expenditure following transhiatal oesophagectomy is lower than that after transthoracic oesophagectomy; this may be a result of reduced surgical stress.

Adult↗
PubMed1991

[A modified translocation technique for recurrent periannular endocarditis after aortic valve replacement].

We reported a patient of 46-year-old man, who had undergone reinforced aortic valve replacement using a composite Björk-Shiley prosthesis for infective endocarditis on April 13, 1988. Because of recurrent periannular endocarditis and periprosthetic dehiscence, reoperation was undertaken eighteen months after the initial operation. Following debridement, a composite Dacron vascular prosthesis with a St. Jude Medical valve and two saphenous vein grafts were transposed in the ascending aorta. The operative procedures were entirely smooth. A modified Danielson's technique may be adequate for recurrent periannular endocarditis which make orthotopic re-replacement impossible in most cases.

Aortic Valve↗