Biocompatibility of zirconia dispersed hydroxyapatite ceramics

Because of the lack of adequate strength and toughness, hydroxyapatite (HA) ceramic can not be used for a substitute for a bone and joint despite its excellent affinity for the bone. The present authors have succeeded in producing a new type of HA ceramic containing zirconia. This new ceramic material is superior to ordinary HA ceramic in quality and exceeds compact bone in bending strength and fracture toughness. The Young's modulus was about 3-4 times greater than that of compact bone. The new ceramic material contained either 1.6 or 50% of zirconia by volume and was produced using a special technique to disperse the metal dioxide. In order to assess their affinity for the bone, the new ceramic materials were implanted into rabbit femurs. Sections of the bones removed at different times after operation were prepared without decalcification and subjected to optical microscopy, scanning electronmicroscopy (SEM), and electron-probe X-ray microanalyser (EPMA). The formation of direct chemical bonds with the bone was seen without intervening membrane. Thus, the new ceramic material was shown to have an excellent affinity for the bone, comparable to that of ordinary HA ceramic.     

A surgical case of aortic regurgitation with Beh?et disease

A case of Beh?et disease associated with aortic valve regurgitation treated with aortic valve replacement is reported. The patient was treated successfully with special surgical techniques for prevention of post operative paravalvular leakage and occurrence of pseudo aneurysm because the patient was under long-term steroid therapy for Beh?et disease.     

Severe lightning pain during spinal anesthesia

A 74-yr-old man was scheduled for the biopsy of prostatic tumor under spinal anesthesia. Preoperative serologic test for syphilis was highly positive. Spinal anesthesia was performed in the sitting position, and 2 ml of hyperbaric Neo-percamine S (a mixture of 0.24% dibucaine and 0.12% T-caine) was administered uneventfully with the onset of warm sensation on the perineal region. Ten minutes later, however, he began to complain of severe lightning sensation on the feet. After giving pentazocine intravenously, the short cystoscopic procedure was completed. As a cause of severe pain, an erroneous anesthetic solution or direct neuronal injury had been excluded because of rapid and complete recovery after anesthesia. Two weeks later, he was scheduled for TUR-P. He again complained of severe lightning pain after the successful spinal anesthesia with the same anesthetic solution. Because the pain was not relieved by analgesics, he was then anesthetized with enflurane and N2O in oxygen, and there were no neurological complications after anesthesia. Several cases of severe pain during spinal anesthesia have been reported in patients with tabes dorsalis. Although the patient lacks clear symptoms of neurosyphilis, positive serologic examination for syphilis without any other possible causes suggests altered sensitivity of the spinal cord to anesthetic solutions.     

Health promotion and disease prevention in HMOs: a survey of newly established IPAs in New York City

Independent Practice Associations (IPAs) are the fastest growing segment of the Health Maintenance Organization (HMO) industry, but little is known about their provision of health promotion and disease prevention to subscribers. To examine the extent to which IPA policies encourage health promotion and disease prevention, we interviewed medical directors and other senior administrators of six newly developing IPA-HMOs in New York City. We also reviewed promotional literature to assess how extensively health promotion and disease prevention were marketed to the potential subscriber. Although medical protocols for preventive screening exist in most IPAs, compliance with guidelines is left largely to the individual physician's judgment for implementation. IPA respondents suggested that their physician panels are oriented toward prevention, but there is uncertain evidence in this regard, and incentive payments could discourage referrals for screening. Health education programs are sporadic. Health promotion and disease prevention do not appear to be a high priority among six newly established IPAs in New York City. We recommend several steps that would encourage IPA-HMOs to increase their health promotion activities.     

Effects of mifepristone on rabbit intraocular pressure in the presence and absence of dexamethasone

Topical dexamethasone was used to elevate rabbit intraocular pressure in order to study the interaction with a steroid antagonist, mifepristone. Dexamethasone did not cause a consistently significant increase in intraocular pressure. Animals treated with mifepristone followed by dexamethasone showed no apparent increase in intraocular pressure after dexamethasone, indeed mifepristone caused a lower intraocular pressure than seen in other groups whether in the presence or absence of dexamethasone. Reductions of intraocular pressure when mifepristone was given after 14 days of dexamethasone administration were not found. No conclusion can be reached regarding any dexamethasone antagonism by mifepristone, except that intraocular pressure tended to be lower even in the presence of dexamethasone.     

31P nuclear magnetic resonance study of intrahepatic energy metabolism in acute liver failure

Changes in phosphorus metabolites and intracellular pH in acute liver failure induced by D-galactosamine (GAL) were evaluated non-destructively and continuously using 31P-NMR spectroscopy. Furthermore, changes in these parameters under ischemia were also examined. GAL(1.0g/kg) was injected intravenously to male Wistar rats. NMR measurements in perfused livers were performed with a GX-270FT NMR spectrometer (JEOL). Typical changes in 31P-NMR spectra were observed after GAL administration. ATP levels decreased to 57.4 +/- 12.4% at 12 hours and to 65.4 +/- 7.7% at 24 hours after the administration compared with that in control rats. Pi levels increased remarkably to 632.1 +/- 76.4% at 3 hours and recovered to 127.5 +/- 22% at 24 hours. NAD+/NADH and UDP-sugar levels gradually increased to 253.5 +/- 33.4 and 456.3 +/- 60.9%, respectively, at 24 hours. In GAL treated livers, ATP levels fell rapidly and Pi levels rose correspondingly during ischemia, and they rapidly recovered by reperfusion. The intracellular pH decreased to 7.16 +/- 0.032 from 7.38 +/- 0.065 at 3 hours after GAL administration. However, significant changes in pH were not observed until 24 hours. In GAL treated livers, slight changes in pH were observed under ischemia. These results indicate that 31P-NMR is a useful method to evaluate the damage of acute liver failure, and to diagnose liver diseases involving the intrahepatic energy metabolism.     

The use of the helium-neon laser in the treatment of amblyopia in children

The authors analyze the efficacy of He-Ne laser therapy of amblyopia of various origins in 48 children (81 eyes). Group 1 children were not treated at all in order to assess the visual function background fluctuations (absolute controls). Along with He-Ne laser, used in Group 2, a 'placebo', slit lamp with blinking light, was used in Group 3. Vision acuity was assessed with the use of Sivtsev-Golovin's and Orlova's tables and by visocontrastometry in a blind test. Common visometry has shown a reliable and approximately similar improvement of the vision acuity in Groups 2 and 3 patients, whereas visocontrastometry has not detected any changes of visual function in all the 3 groups. These results cast doubt on the true efficacy of He-Ne laser stimulation of visual function, at least in children, and once again demonstrate that such investigations may be carried out only with a reliable ('blind') control and placebo.     

Replantation of the distal part of the leg

We successfully replanted five amputated legs in five patients and followed the patients for two years or more (average, six years and three months). Although some patients found it impossible to squat and to run because of joint contractures, muscle weakness, or deformities of the foot, all patients could perform other activities without difficulty. None had important pain or any intolerance to cold, and all were satisfied with the results of the replantation.