Optimal positive airway pressure predicts oral appliance response to sleep apnoea.

Patients with less severe obstructive sleep apnoea (OSA) are usually prescribed oral appliances and/or smaller optimal nasal continuous positive airway pressure (P(nCPAP)) in nCPAP therapy. We hypothesised that OSA patients with greater P(nCPAP) would not respond favourably to oral appliances. Oral appliances were inserted in nCPAP users after washing-out the nCPAP effect. Follow-up polysomnography was undertaken with the adjusted oral appliance in place. The predictability of P(nCPAP) was evaluated with receiver-operating characteristic (ROC) curves. The median baseline apnoea/hypopnoea index (AHI) was reduced with the oral appliance from 36 to 12 events.h(-1) in 35 patients. When responders were defined as patients showing a follow-up AHI of <5 events.h(-1) with >50% reduction in baseline AHI, the area under the ROC curve for P(nCPAP) was 0.76. The best cut-off value of P(nCPAP) turned out to be 10.5 cmH(2)O with a high negative predictive value (0.93) and a low negative likelihood ratio (0.18). OSA patients with a P(nCPAP) of >10.5 cmH( 2)O are unlikely to respond to oral appliance therapy. This prediction is clinically helpful to both OSA patients and medical personnel in discussing oral appliances as a temporary substitute and/or alternative for nCPAP.

Distribution of motoneurons involved in the prey-catching behavior in the Japanese toad, Bufo japonicus.

Coordinated activities of several muscles in the head region underlie the prey-catching behavior of anuran amphibians. As a step in elucidating the neural mechanisms generating these activity patterns in the Japanese toad, we labelled the motoneurons innervating 8 behaviorally relevant muscles using intramuscular (i.m.) injection technique of horseradish peroxidase (HRP), and examined their localization within the motor nuclei whose boundaries were determined by HRP application to the nerve trunk. All the motoneurons innervating the two jaw closer muscles (m. masseter major, m. temporalis) and m. submentalis were localized within the rostral subdivision of the trigeminal motor nucleus. The motoneurons innervating the only mouth opener muscle (m. depressor mandibulae) were scattered throughout the facial motor nucleus. The motoneurons innervating tongue (m. hypoglossus, m. genioglossus) and hyoid muscles (m. sternohyoideus, m. geniohyoideus) appeared within the hypoglossal nucleus with distribution patterns characteristic of the target muscles. Thus, we have revealed the neuroanatomical organization of the motoneurons relevant to the prey-catching behavior.

Amperometric recording of gonadotropin-releasing hormone release activity in the pituitary of the dwarf gourami (teleost) [correction of (teleosat)] brain-pituitary slices.

We developed a method for real-time electrochemical recording of gonadotropin-releasing hormone (GnRH) release using carbon fiber electrodes (CFE). The oxidation current of GnRH was measured by amperometry. We recorded the release activity in the pituitary of the teleost brain-pituitary slice. The CFE was located in the part of the pituitary that receives dense innervation from GnRH neurons in the preoptic area. A bulk amperometric current was recorded in response to high K+(o) stimulation in a dose dependent manner. Decreasing the holding potential to below the oxidation potential of GnRH resulted in the loss of amperometric currents. Thus, it is suggested that the amperometric currents are mainly attributed to the oxidation currents of GnRH and reflect the GnRH release activity.

Improvement of therapeutic effect of human recombinant superoxide dismutase on ischemic acute renal failure in the rat via cationization and conjugation with polyethylene glycol.

Therapeutic effect of superoxide dismutase (SOD) and three derivatives: a conjugate with polyethylene glycol (SOD-PEG2), a cationized derivative (cSOD), and a mannosylated derivative (Man-SOD), on acute renal failure induced by ischemia/reperfusion was studied in rats. SOD and derivatives were administered intravenously to the rat after nephrectomy of the right kidney and before and after 60 min occlusion of the left renal artery. At 48 hr after reperfusion, the renal function was evaluated by determining the urinary excretion rate of 14C-inulin injected intravenously. No therapeutic effect on the impaired renal function was shown in the case of low dose SOD (2600 unit/kg) treatment. In contrast, administration of cSOD which was shown to be taken up by the isolated perfused kidney from its capillary side and SOD-PEG2 which maintained high plasma concentration exhibited significant therapeutic effect, as did SOD at ten-fold higher dose (26,000 unit/kg). On the other hand, renal damage was promoted by Man-SOD. Thus, the present study demonstrated that chemical modification may improve the therapeutic effect of SOD on the ischemic acute renal failure and increased SOD concentration in the renal vascular space is an important factor for the improved effect.

Creation and use of a composite polyurethane-expanded polytetrafluoroethylene graft for hemodialysis access.

The Thoratec (Vectra) polyurethane vascular access graft (TPVA) is among the most recent additions to the list of materials used to construct prosthetic grafts for vascular access during hemodialysis. We give the TPVA very high marks, and recognize the utility of such a graft for use in hemodialysis. However, the strong elasticity of this graft can lead to unexpected complications after suturing. We devised a new surgical method using a TPVA-ePTFE (expanded polytetrafluoroethylene) composite graft, substituting the anastomosis section of the TPVA with a portion of ePTFE graft material, and have been able to overcome most of the TPVA's potential problems. We herein describe the technique.

[Obstruction of the inferior vena cava at the hepatic portion--surgical management and prognosis of 11 cases].

Eleven patients with obstruction of the inferior vena cava at the hepatic portion were reviewed. In these patients, 7 had membranous obstruction and underwent balloon membranotomy. Pressure gradient between inferior vena cava and right atrium was 13.1 +/- 5.1 mmHg (mean +/- S.D.) and after membranotomy, this fell down to 7.0 +/- 1.9 mmHg. Four patients had long segmental obstruction, and cavoatrial bypass grafting with 16 mm ring reinforced Expanded-Polytetrafluoroethylene graft in 3 and bidirectional digital-instrumental membranotomy in one, were done, respectively. In 2 of 7 patients with membranous obstruction, transcardiac membranotomy was followed. These 3 procedures were so effective that pressure gradient between inferior vena cava and right atrium was 11.7 +/- 3.4 mmHg preoperatively, and after operation, this fell down to 1.7 +/- 0.7 mmHg. During the follow-up period from 8 months to 9 years (mean 4 years and one month), all patients are alive with remarkable improvement of clinical symptoms and signs. It is concluded that balloon membranotomy for membranous obstruction and cavoatrial bypass grafting for long segmental obstruction of the inferior vena cava at the hepatic portion would be recommended.

Massive actin polymerization induced by phosphatidylinositol-4-phosphate 5-kinase in vivo.

The Rho family GTP-binding proteins have been known to mediate extracellular signals to the actin cytoskeleton. Although several Rho interacting proteins have been found, downstream signals have yet to be determined. Many actin-binding proteins are known to be regulated by phosphatidylinositol 4,5-bisphosphate in vitro. Rho has been shown to enhance the activity of phosphatidylinositol-4-phosphate 5-kinase (PI4P5K), the phosphatidylinositol 4,5-bisphosphate synthesizing enzyme. Recently we isolated several isoforms of type I PI4P5K. Here we report that PI4P5K Ialpha induces massive actin polymerization resembling "pine needles" in COS-7 cells in vivo. When truncated from the C terminus to amino acid 308 of PI4P5K Ialpha, both kinase activity and actin polymerizing activity were lost. Although the dominant negative form of Rho, RhoN19, alone decreased actin fibers, those induced by PI4P5K were not affected by the coexpression of RhoN19. These results suggest that PI4P5K is located downstream from Rho and mediates signals for actin polymerization through its phosphatidylinositol-4-phosphate 5-kinase activity.

An infection-resistant PTFE vascular graft; spiral coiling of the graft with ofloxacin-bonded PTFE thread.

OBJECTIVE: To develop an infection-resistant polytetrafluoroethylene (PTFE) vascular graft for potential clinical use in grafting in sites of bacterial contamination and in replacement of the infected grafts. SETTING: Experimental study in rabbits. MATERIALS AND METHODS: An antibiotic ofloxacin (OFLX) was bonded to a sheet of PTFE by impregnation, which was cut and twisted into fine threads. The in-vitro antibacterial activity of OFLX-PTFE thread was determined by measuring the zone of growth inhibition against Escherichia coli. The thread was spirally coiled around a ridged outerwall PTFE to make the OFLX-PTFE graft. OFLX-PTFE graft or control graft was interposed in the inferior vena cava (IVC) of rabbits and the entire graft was covered with fibrin containing a fixed number of E. coli. Three or 7 days after the grafting, the grafts with perigraft tissue were harvested and subjected to bacteriological studies. RESULTS: In spite of early phase rapid elution of OFLX, a significant antibacterial activity was retained for more than 2 weeks. The antibacterial activity of OFLX-PTFE threads implanted in the subcutaneous space of rabbits decreased to 48% after 24 h and to approximately 1% after a week. The swab culture of all the control grafts was positive, while only one of 13 PTFE-OFLX grafts was positive. The number of viable bacteria in the perigraft tissue of OFLX-PTFE grafts was remarkably low in comparison with that of control grafts. Thus, the OFLX-PTFE grafts exhibited a marked in-vivo antibacterial activity. CONCLUSION: By a unique method, it was possible to furnish PTFE graft with an excellent infection-resistant property, without affecting the original biological behaviour.