Comparison of a vitamin E-infused highly crosslinked polyethylene insert and a conventional polyethylene insert for primary total knee arthroplasty at two years postoperatively.

AIMS: The use of vitamin E-infused highly crosslinked polyethylene (HXLPE) in total knee prostheses is controversial. In this paper we have compared the clinical and radiological results between conventional polyethylene and vitamin E-infused HXLPE inserts in total knee arthroplasty (TKA). PATIENTS AND METHODS: The study included 200 knees (175 patients) that underwent TKA using the same total knee prostheses. In all, 100 knees (77 patients) had a vitamin E-infused HXLPE insert (study group) and 100 knees (98 patients) had a conventional polyethylene insert (control group). There were no significant differences in age, sex, diagnosis, preoperative knee range of movement (ROM), and preoperative Knee Society Score (KSS) between the two groups. Clinical and radiological results were evaluated at two years postoperatively. RESULTS: Differences in postoperative ROM and KSS were not statistically significant between the study and control groups. No knee exhibited osteolysis, aseptic loosening, or polyethylene failure. Additionally, there was no significant difference in the incidence of a radiolucent line between the two groups. One patient from the study group required irrigation and debridement, due to deep infection, at six months postoperatively. CONCLUSION: Clinical results were comparable between vitamin E-infused HXLPE inserts and conventional polyethylene inserts at two years after TKA, without any significant clinical failure. Cite this article: Bone Joint J 2019;101-B:559-564.

Usefulness of an accelerometer-based portable navigation system in total knee arthroplasty.

AIMS: The aim of this study was to evaluate the effects of using a portable, accelerometer-based surgical navigation system (KneeAlign2) in total knee arthroplasty (TKA) on the alignment of the femoral component, and blood loss. PATIENTS AND METHODS: A total of 241 consecutive patients with primary osteoarthritis of the knee were enrolled in this prospective, randomised controlled study. There were 207 women and 34 men. The mean age of the patients was 74.0 years (57 to 89). The KneeAlign2 system was used for distal femoral resection in 121 patients (KA2 group) and a conventional intramedullary femoral guide was used in 120 patients (IM group). RESULTS: One patient (0.8%) in the KA2 group and 19 in the IM group had an alignment which was > 3° away from the neutral mechanical axis (p < 0.01). The mean deviation from neutral alignment was 1.01° (standard deviation (sd) 1.0°) in the KA2 group and 1.93° (sd 1.7°) in the IM group (p < 0.01). Blood loss was significantly less in the KA2 group compared with the IM group (784 ml (sd 357) versus 1071 ml (sd 310), p < 0.001). CONCLUSION: The KneeAlign2 system provides a technically straightforward method for identifying the femoral head and performing an accurate distal femoral resection at TKA with significantly less blood loss compared with a conventional intramedullary guide. Cite this article: Bone Joint J 2017;99-B:1047-52.

A cemented mobile-bearing total knee replacement prevents periprosthetic loss of bone mineral density around the femoral component: a matched cohort study.

Bone mineral density (BMD) around the femoral component has been reported to decrease after total knee replacement (TKR) because of stress shielding. Our aim was to determine whether a cemented mobile-bearing component reduced the post-operative loss of BMD. In our study 28 knees receiving a cemented fixed-bearing TKR were matched with 28 receiving a cemented mobile-bearing TKR. They underwent dual-energy x-ray absorptiometry, pre-operatively and at three weeks and at three, six, 12, 18 and 24 months post-operatively. The patients were not taking medication to improve the BMD. The pre-operative differences in the BMD of the femoral neck, wrist, lumbar spine and knee in the two groups were not significant. The BMD of the femur decreased postoperatively in the fixed-bearing group, but not the mobile-bearing group. The difference in the post-operative change in the BMD in the two groups was statistically significant (p < 0.05) at 18 and 24 months. Our findings show that a cemented mobile-bearing TKR has a favourable effect on the BMD of the distal femur after TKR in the short term. Further study is required to determine the long-term effects.

The incidence of the patellar clunk syndrome in a recently designed mobile-bearing posteriorly stabilised total knee replacement.

The patellar clunk syndrome describes painful catching, grinding or jumping of the patella when the knee moves from a flexed to an extended position after total knee replacement (TKR). The posterior stabilised TKR had been noted to have a higher incidence of this problem. Mobile-bearing posteriorly stabilised TKRs have been introduced to improve patellar tracking and related problems by a mechanism of self-alignment. We evaluated the patellar clunk syndrome in 113 knees in 93 patients with such a TKR at a mean follow-up of 2.3 years (2.0 to 3.2). The syndrome was identified in 15 knees (13.3%). Logistic regression analysis showed that the absolute value of the post-operative angle of patellar tilt was significantly associated with the occurrence of patellar clunk (p = 0.025). Patellar tracking should be carefully checked during surgery.

Halothane-dependent lipid peroxidation in human liver microsomes is catalyzed by cytochrome P4502A6 (CYP2A6).

BACKGROUND: Halothane is extensively (approximately 50%) metabolized in humans and undergoes both oxidative and reductive cytochrome P450-catalyzed hepatic biotransformation. Halothane is reduced under low oxygen tensions by CYP2A6 and CYP3A4 in human liver microsome to an unstable free radical, and then to the volatile metabolites chlorodifluoroethene (CDE) and chlorotrifluoroethane (CTE). The free radical is also thought to initiate lipid peroxidation. Halothane-dependent lipid peroxidation has been shown in animals in vitro and in vivo but has not been evaluated in humans. This investigation tested the hypothesis that halothane causes lipid peroxidation in human liver microsomes, identified P450 isoforms responsible for halothane-dependent lipid peroxidation, and tested the hypothesis that lipid peroxidation is prevented by inhibiting halothane reduction. METHODS: Halothane metabolism was determined using human liver microsomes or cDNA-expressed P450. Lipid peroxidation was quantified by malondialdehyde (MDA) formation using high-pressure liquid chromatography-ultraviolet analysis of the thiobarbituric acid-MDA adduct. CTE and CDE were determined by gas chromatography-mass spectrometry. RESULTS: Halothane caused MDA formation in human liver microsomes at rates much lower than in rat liver microsomes. Human liver microsomal MDA production exhibited biphasic enzyme kinetics, similar to CDE and CTE production. MDA production was inhibited by the CYP2A6 inhibitor methoxsalen but not by the CYP3A4 inhibitor troleandomycin. Halothane-dependent MDA production was catalyzed by cDNA-expressed CYP2A6 but not CYP3A4 or P450 reductase alone. CYP2A6-catalyzed MDA production was inhibited by methoxsalen or anti-CYP2A6 antibody. CONCLUSIONS: Halothane causes lipid peroxidation in human liver microsomes, which is catalyzed by CYP2A6, and inhibition of halothane reduction prevents halothane-dependent lipid peroxidation in vitro.

Possibility of "distraction arthrogenesis": first report in rabbit model.

We investigated the possibility of articular cartilage distraction for use in reconstructing joint structure and for increasing the donor site of osteochondral grafts. Intraarticular osteotomy was performed at the femoral condyle in 12 Japanese white rabbits. The bone segment was fixed with a specially designed external fixator. After a 3-week waiting period, distraction was performed intermittently for 3 weeks (0.7 mm x 3 times per week) in the distraction group (n = 7) and, in the remaining animals (gap group; n = 5), a gap of 6.3 mm in length was made at surgery. All rabbits received etidronate injections (20 mg/kg x2 times per week) for 5 weeks, to slow mineralization. The femoral condyle was harvested 9 weeks postoperatively and decalcified sagittal sections were stained and evaluated, using a histological grading scale. In the distraction group, distraction of 4.2 +/- 1.4 mm was achieved, and the distracted cartilage area was filled with regenerated cartilage, without any gap between the regenerated and the adjacent articular cartilage. This regenerated cartilage showed metachromasia with toluidine blue. In the gap group, newly formed cartilage tissue was folded from the edge of the osteotomy site and fibrous tissue was interposed in the gap. The histological grading score was significantly lower in the distraction group (P < 0.02). Our preliminary results demonstrated the possibility of cartilage distraction; however, long-term observation will be necessary to confirm the characteristics of the distracted cartilage. We may call the process "distraction arthrogenesis", because the entire articular entity, which consists of cartilage, subchondral bone, and bone, could be distracted at once.

[Effects of allopurinol on renal damage following renal ischemia].

We investigated the effects of allopurinol on renal damage following renal ischemia. Male Wistar rats weighing 250-300 g were classified into enflurane and allopurinol groups and anesthetized for 5 minutes using 1.7 MAC of enflurane in 30% oxygen. Then the left renal artery was dissected and clamped. Arterial occlusion was performed under 1.3 MAC enflurane for 30 minutes. Anesthesia was maintained for an additional 90 minutes after releasing the clip. In the allopurinol group, the rats were administered with allopurinol 3 mg.kg-1 intravenously prior to renal ischemia. At the end of anesthesia and 24 hours after the discontinuation of anesthesia, the necrotic areas, kidney weight/body weight ratios, gamma-GTP and NAG activities of the kidney which had been clamped were examined. Urinary gamma-GTP and NAG activities and serum inorganic fluoride concentrations were also measured. The necrotic area was significantly smaller in the allopurinol group than in the enflurane group. The activity of gamma-GTP in the kidney was higher in the allopurinol group than in the enflurane group. The kidney weight/body weight ratio was lower in the allopurinol group than in the enflurane group. There was no difference in serum inorganic fluoride concentration between the allopurinol and enflurane groups. These results suggest that allopurinol decreases renal damage following renal ischemia under enflurane anesthesia.

The effects of inhalational anesthetics on ischemic injury of rat kidney with renovascular occlusion.

The effects of halogenated inhalational anesthetics, viz. halothane, enflurane, isoflurane and sevoflurane, on ischemic rat kidneys were studied through the response of renal gamma-glutamyl transpeptidase in the brush border of proximal tubules to monoclonal antibodies. Brush border staining characteristics were evaluated as follows: a) continuous (normal), b) discontinuous (damaged) and c) indistinct (necrotic). The isoflurane group had significantly fewer damaged and/or necrotic proximal tubules compared to the other groups. These results suggest that isoflurane is the most appropriate inhalational anesthetic when renal circulation is impaired.

[Hypercapnea during facial surgery under local anesthesia].

We examined the ventilation of patients whose faces were draped during facial surgery under local anesthesia. Ten patients who underwent eye surgery received hydroxyzine 25 mg and pentazocine 15 mg i.m. before local anesthesia. Arterial blood samples and end-tidal respiratory gases from nasal cannulae were collected at the following selected times: before draping their faces, 10 min, 30 min, 60 min after draping, and after the drapes were removed. Both arterial carbon dioxide tension (42 +/- 1 mmHg before draping and 46 +/- 1 mmHg at 10 min) and end-tidal carbon dioxide tension (33 +/- 2 mmHg before draping and 36 +/- 1 mmHg at 10 min) were elevated significantly after their faces were draped. Hypercapnea was completely eliminated by suctioning the expired gases. It is concluded that hypercapnea is inevitable during face or neck surgery under local anesthesia, and that the expired gases should be monitored and removed.

Cloning of murine megakaryocyte progenitor cells in a fibrin clot culture system.

A fibrin clot culture system was applied to the cloning of mouse megakaryocyte colony-forming cells (CFU-Meg). The culture medium in this new method consists of Iscove's minimal essential medium containing fetal bovine serum, bovine fibrinogen, bovine thrombin, and pokeweed mitogen-stimulated mouse spleen cell-conditioned medium (PWM-SCM). CFU-Meg colony frequency with 10% PWM-SCM was maximal on days 5-6 of culture. Plating efficiencies averaged 36.1 +/- 3.9 and 51.9 +/- 6.0 per 1.5 X 10(5) BDF1 bone marrow cells and 1.0 X 10(6) spleen cells, respectively. The addition of bovine serum albumin to the culture medium had no effect on the efficiency of megakaryocyte colony growth in this culture system. This simplified and reproducible culture system supported not only the growth of colonies composed of megakaryocytes in "synchronous maturation," but also so-called "heterogenous" megakaryocyte colonies composed of cells in all stages of maturation.

2-Methylthio-1,4-naphthoquinone, a unique sulfur-containing quinone from a thermophilic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus.

A quinone was extracted and purified from the cells of an extremely thermophilic hydrogen bacterium, Hydrogenobacter thermophilus TK-6 (IAM 12695). Its chemical structure was determined as 2-methylthio-3-VI, VII-tetrahydromultiprenyl-1,4-naphthoquinone by elemental analysis, 1H nuclear magnetic resonance spectroscopy, mass spectroscopy, and infrared spectroscopy of the quinone and by gas-liquid chromatography and gas chromatography-mass spectroscopy analysis of the ozonolysis products of the quinone. It was shown that the other five strains of H. thermophilus have the same quinone system. We named the quinone with the 2-methylthio-1,4-naphthoquinone nucleus "methionaquinone." The abbreviation of MTK is recommended for this class of quinone.

Microbial oxidation of hydrocarbons and related compounds by whole-cell suspensions of the methane-oxidizing bacterium h-2.

Previously, a thermophilic obligate methane-oxidizing bacterium, H-2 (type I), was isolated in our laboratory. H-2 is a new type of methylotroph because of the G+C content of DNA; it uses both the ribulose monophosphate pathway and the serine pathway for carbon assimilation and possesses a new quinone. In addition, we found that resting cell suspensions of H-2 had the ability to oxidize a variety of compounds different from the other methane-oxidizing bacteria as follows. (i) C(1) to C(8)n-alkanes are hydroxylated and further oxidized, yielding mixtures of the corresponding alcohols, aldehydes, acids, and ketones. Liquid alkanes are transformed through a different oxidative pathway from that of gaseous ones. (ii) Both gaseous (C(2) to C(4)) and liquid (C(5), C(6)) n-alkenes are oxidized to their corresponding 1,2-epoxides. (iii) Liquid monochloro and dichloro n-alkanes (C(5), C(6)) are oxidized, yielding their corresponding acids or haloacids. (iv) Diethyl ether is oxidized to acetic acid; no ethanol and acetaldehyde are detected. (v) Cyclic and aromatic compounds are also oxidized. (vi) Secondary alcohols (C(3) to C(10)) are oxidized to their corresponding methyl ketones.

Metabolism of T-2 toxin in Curtobacterium sp. strain 114-2.

The metabolic pathway of T-2 toxin in Curtobacterium sp. strain 114, one of the T-2 toxin-assimilating soil bacteria, was investigated by thin-layer and gas-liquid chromatographic analyses. T-2 toxin added to the basal medium as a single carbon and energy source was biotransformed into HT-2 toxin and an unknown metabolite. Infrared, mass spectrum, proton magnetic resonance, and other physico-chemical analyses identified this new metabolite as T-2 triol. T-2 toxin was first deacetylated by the bacterium into HT-2 toxin, and this metabolite was then biotransformed into T-2 triol without formation of neosolaniol and T-2 tetraol. No trichothecenes remained in the culture medium after prolonged culture. Some properties of T-2 toxin-hydrolyzing enzymes were observed with whole cells, the cell-free soluble fraction, and the culture filtrate. Besides T-2 toxin, trichothecenes such as diacetoxyscirpenol, neosolaniol, nivalenol, and fusarenon-X were also assimilated by this bacterium.

Coexistence of different pathways in the metabolism of n-propylbenzene by Pseudomonas sp.

Pseudomonas desmolytica S449B1 and Pseudomonas convexa S107B1 grown on n-propylbenzene oxidized n-propylbenzene to beta-phenylpropionic acid and benzoic acid by initial oxidation of the n-propyl side chain and the following beta-oxidation, respectively. The same strains also oxidized n-propylbenzene to 3-n-propylcatechol by initial oxidation of positions 2 and 3 of the aromatic nucleus. A ring fission product, 2-hydroxy-6-oxononanoic acid, was also isolated from the culture broth. Together with the results of oxygen uptake experiments, the data obtained suggested not only the existence of a reductive step to form 2-hydroxy-6-oxononanoic acid, but also the coexistence of two different pathways in the metabolism of n-propylbenzene by the strains used.