全膝关节置换术后的骨溶解：胫骨盘表面的修饰及聚乙烯衬垫灭菌方法对其的影响术 后5至10年的报告

背景：从关节和胫骨假体聚乙烯衬垫后表面转移磨损碎屑，是全膝关节置换术后假体周围骨溶解的主要原因。全膝人工关节假体设计随时问而发生变化，例如对胫骨盘近端表面的粗糙度和聚乙烯衬垫的灭菌方法。我们假设胫骨盘表面抛光和采用空气中γ射线照射之外的其他方法对衬垫灭菌，可降低骨溶解的发生率。方法：从1987年至1998年，我们采用后十字韧带保留型的解剖型组配式全膝人工关节假体系列。对300名患者施行365例全膝关节置换术。术后5至10年，对这些患者的膝关节摄正、侧位X线片。由两位关节置换专家对X线片上的骨溶解状况进行单独评定（骨溶解的界定标准为假体周围存在边缘清晰的非线性松质骨丢失区）。结果：在粗糙表面的胫骨盘的242例膝关节中，使用空气中γ射线照射灭菌的衬垫固定，有34％（82例）骨溶解阳性。用惰性气体中γ射线照射或没有照射的衬垫与抛光表面连接的98例膝关节中，有9％（9例）骨溶解阳性。骨溶解与六项因素相关，这些因素为：一项与患者（男性）相关、一项与胫骨盘（近端表面抛光）相关、三项与聚乙烯衬垫（加工的原材料、灭菌方法及存放时间）相关及一项与手术技术（股骨假体与胫骨假体间的过伸）相关。结论：在这类假体设计中，胫骨盘近端表面采用抛光及衬垫采用更为先进的灭菌方法（不用空气中γ射线照射灭菌）能显著减少骨溶解的发生率，但不能避免骨溶解。     

Absence of Developmental Effects in CF-1 Mice Exposed to Aspartame in Utero

Aspartame (L-aspartyl-L-phenylalanine methyl ester) is a widelyused high potency dipeptide sweetener. Developmental toxicologystudies have been performed in several species documenting noeffects of high doses of aspartame. Recently, a study by Mahalikand Gautieri ((1984) Res Commun. Psychol Psychiatry Behav. 9,385–403) reported a delay in the achievement age for thevisual placing response in mice pups after maternal administrationof high dosages of aspartame during late gestation. In the presentstudy developmental parameters were determined in offspringof CF-1 mice after maternal administration of aspartame at 500,1000, 2000, and 4000 mg/kg body wt by oral gavage. Aspartamewas administered on Days 15 through 18 of gestation. Maternalbody weight, food consumption, gestation length, reproductiveindices, and litter size were not affected by aspartame treatment.In the pups, body weights, negative geotaxis, and surface andmidair righting reflexes were not altered by treatment. Therewas no delay in the development of the visual placing responseregardless of the method employed for assessment (grid or rope)or the manner by which the data were analyzed. There were alsono changes in time of eye opening, reflex pupil closure, andophthalmoscopic examination in the offspring. Thus, neitherphysical nor functional development was altered in mice afterin utero exposure to extremely large dosages of aspartame. Morespecifically, in utero exposure to aspartame did not affectthe development of the visual system in mice.     

DOES PRETREATMENT WITH CIMETIDINE AND RANITIDINE AFFECT THE DISPOSITION OF BUPIVACAINE ?

Thirty patients who chose extradural analgesia for electiveCaesarean section were pretreated, by random selection, withcimetidine 400 mg, ranitidine 150 mg or no H₂-blocker. Followingthe administration of 0.5% bupivacaine, no significant differencewas found between peak plasma bupivacaine concentrations orarea under the plasma bupivacaine concentration-time curve (AUC)in these three groups. This study shows that a single dose ofcimetidine or ranitidine does not affect significantly the dispositionof bupivacaine in the obstetric patient.     

The localization of the target antigens and antibodies in linear IgA disease is heterogeneous, and dependent on the methods used

Fifty-nine patients with linear IgA disease, 24 with onset in childhood and 35 with adult onset, were studied. Sera from all patients were tested by indirect immunofluorescence, using as substrates intact normal skin and normal skin which had been split through the lamina lucida region of the basement membrane zone by suction and by prolonged incubation with molar NaCl. This enabled the site of the target antigen for the circulating IgA antibodies to be determined. The sites of deposition of the IgA antibodies in vivo were detected by raising a suction blister in eight patients, and splitting seven patients’ biopsies by prolonged incubation with molar NaCl. Eighteen sera were positive with intact skin, and 34 with split skin. Twenty-nine sera were positive with suction blisters as substrate; 14 bound to the epidermal aspect of the split skin, seven in a combined pattern (binding to the epidermis and dermis) and six to the dermal aspect. Thirty-one sera bound to salt-split skin, 24 to the epidermal side and seven on the dermal side. There was discordance between the two methods of skin splitting in 15 sera. Seven sera gave a combined pattern with suction but with salt-split skin, five of these bound epidermally, one was dermal, and one negative. Five sera showed epidermal binding on saltsplit skin and were negative on suction blisters, and the reverse was seen with one serum. Two sera gave variable results on suction blisters. Direct immunofluorescence studies showed dermal binding on all eight patients with suction blisters, and epidermal binding in four and dermal binding in three patients with salt splitting. These results demonstrate that the location of the target antigens and the sites of deposition of the antibodies are dependent on the methods used. They also suggest that there are at least two different antigens, an epidermal- and a dermal-associated antigen. The sera reacting in the combined pattern may represent antibodies reacting with a different epitope of the epidermal antigen, with a further epidermal antigen, or with two target antigens.     

A CONTINUOUS SUBDURAL BLOCK

We describe a case of accidental subdural block, after attemptedextradural puncture for Caesarean section. Fractionation ofthe local anaesthetic dose led to avoidance of more seriouscomplications. Subdural fentanyl and a continuous low-dose subduralinfusion were used satisfactorily for intra-operative managementand postoperative analgesia. As little as 0.5 ml of bupivacaine,hourly, provided satisfactory analgesia over a 15-h period.(Br. J. Anaesth. 1993; 70: 462–465)     

The effect of three H2-receptor antagonists on the disposition of midazolam in the rat in-situ perfused liver model

Abstract— The rat in-situ perfused liver model was used to investigate the effect of three H₂-receptor antagonists on the pharmacokinetic disposition of the short-acting benzodiazepine, midazolam. Perfusion experiments, using standard techniques, were carried out on four groups (one control and three H₂-receptor antagonist-treated groups) of male Sprague-Dawley rats (300–350 g). All animals received midazolam 1 mg; the three treated groups received Cimetidine (8 mg), ranitidine (3 mg) or famotidine (0.4 mg). Perfusate and bile samples were collected and assayed for midazolam using gas chromatography. The perfusate data indicated that midazolam disposition was impaired at 10, 50 and 60 min of the experimental period following the addition of cimetidine, whereas ranitidine and famotidine produced an effect at 10 min only; midazolam levels in bile were not affected by the presence of an H₂-receptor antagonist. It was concluded that the limited inhibitory effect of cimetidine may be attributed to its lack of specificity for CYP3A, the isoenzyme responsible for the metabolism of midazolam.