Abstract: Tissue responses to titanium implantation with two different surface conditions in our established implantation model in rat maxillae were investigated by light and transmission electron microscopy and by histochemistry for tartrate‐resistant acid phosphatase (TRAPase) activity. Here we used two types of implants with different surface qualities: titanium implants sandblasted with Al 2 O 3 (SA‐group) and implants coated with hydroxyapatite (HA‐group). In both groups, bone formation had begun by 5 days postimplantation when the inflammatory reaction had almost disappeared in the prepared bone cavity. In the SA‐group, however, the bone formation process in the bone cavity was almost identical to that shown in our previous report using smooth surfaced implants ( Futami et al. 2000 ): new bone formation, which occurred from the pre‐existing bone toward the implant, was preceded by active bone resorption in the lateral area with a narrow gap, but not so in the base area with a wide gap. In the HA‐group, direct bone formation from the implant toward the pre‐existing bone was recognizable in both lateral and base areas. Many TRAPase‐reactive cells were found near the implant surface. On the pre‐existing bone, new bone formation occurred with bone resorption by typical osteoclasts. Osseointegration around the implants was achieved by postoperative day 28 in both SA‐ and HA‐groups except for the lateral area, where the implant had been installed close to the cavity margin. These findings indicate that ossification around the titanium implants progresses in different patterns, probably dependent on surface properties and quality.
Three-dimensional bone scintigraphic images were made and their usefulness and limitations discussed.After usual bone scan procedures, single-photon emission computed tomography (SPECT) data were taken and reconstructed into three-dimensional images. Volume rendering methods were used.Three cases of three-dimensional bone scintigraphy were obtained; one of a normal patient, one of a case of transplanted kidney and incomplete fracture of the left femoral head, and one of a case of degenerative joint disease (DJD) on the left temporomandibular joint (TMJ). The three-dimensional structure of the skeletal system was depicted more clearly by the three-dimensional images than by a conventional bone scan.Three-dimensional bone scintigraphs were thought to provide additional information for better understanding of the nature of bone lesions. Some technical improvements including automated threshold level determination and feature extraction for detecting abnormal high uptake are required before routine use can be envisaged.
This study compared radiological and clinical results of Mallory-Head (Biomet, Warsaw, Indiana) cementless total hip arthroplasty (THA) by anatomical (AP group) or high cup placement (HP group) for Crowe I to III developmental dysplasia of the hip. Of the 68 hips studied, 43 hips were available for 15.3-year follow-up. Ten cups were placed at anatomical center with bulk bone grafting, and 33 cups were at high hip center without bulk bone grafting. No acetabular or femoral components showed loosening in either group. One standard polyethylene liner in a highly placed cup was revised due to excessive wear after 11 years. The average rate of polyethylene wear was 0.128 mm/year in the AP group and 0.148 mm/year in the HP group (except for the revision case). The extent of grafted bone coverage was 34.6% in the AP group. Hip center height was 24.5 mm from the inter-teardrop line in the HP group. The center of the hip horizontal location in the AP group (24.5 mm) and HP group (26.4 mm) was significantly shorter than in normal hips (35.6 mm). Postoperative center-edge angle was 11° (except grafted bone) in the AP group and 25° in the HP group. Mean Harris Hip Score in the AP group improved from 38 points preoperatively to 82 points postoperatively and in the HP group improved from 40 points preoperatively to 88 points postoperatively. Survivorship was 100% in the AP group and 97% in the HP group. Our results indicate that moderate high cup placement without bulk bone grafting at a horizontal locus more medial than that of a normal hip is an alternative durable solution.
New bone formation around cementless stem after total hip arthroplasty is dependent on implant design, material, and mode of porous coating. These osteogenesis patterns are classified as follows, proximal endosteal bone bridging spot welds, increased cortical thickness (cortical hypertrophy) and thin radiodense lines surrounding the tip of the implant (halo pedestal). However, no reports showed the comparison of bone remodelling patterns surrounding stem among diseases: such as osteoarthritis (OA), rheumatoid arthritis (RA), avascular necrosis and neck fracture.
Objectives
The purpose of this study is to clarify whether there are differences of the postoperative bone remodelling pattern around the femoral stem between RA and OA patients.
Methods
Total hip arthroplasty with the Mallory-Head cement less titanium prosthesis has been performed since 1992 in our institute. This tapered stem has plasma spray coating in proximal one third of it. RA group included 18 hips (mean age at operation was fifty-five years old and mean duration of follow-up was 4.6 years). OA group included 70 hips (mean age at operation was fifty-eight years old and mean duration of follow-up was 5.2 years). Anteroposterior radiographs of the hip were made at 6 weeks, 3 months, 6 months, one year and every year after the operation. We evaluated the frequency and time of new bone remodelling appearance around the stem such as spot welds, cortical hypertrophy, and pedestal. We defined that the radiographic signs of instability were progressive subsidence or the presence of radiolucent lines around the porous coating (1). To evaluate the differences in both groups, the Mann-Whitney’s U test and chi-square test were used. P values of less than 0.01 were considered significant.
Results
In both groups, there was no case, which has radiographic sign of instability. Age and intramedurally canal fill of the stem at the operation and follow-up period were not significantly different between RA and OA groups. In endosteal spot welds, the time of its appearance in RA group (2.7 months after operation) was significantly shorter than that in OA group (5.2 months) and the frequency of it did not differ between both groups. However, in halo pedestal, the frequency in RA group (50%) was significantly lower than that in OA group (87%) and the time of its appearance did not differ between both groups. On the other hand, concerning about cortical hypertrophy, time and frequency showed no significant differences between two groups.
Conclusion
We revealed that in RA patients, endosteal spot welds appeared significantly earlier than that in OA patients, and the frequency of halo pedestal was significantly lower than that in OA patients.
We examined the effects of i.c.v. administration of neuro-peptide W-30 (NPW30) on plasma arginine vasopressin (AVP) and plasma oxytocin (OXT) using RIA. The induction of c- fos mRNA, AVP heteronuclear (hn)RNA, and c-Fos protein (Fos) in the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of rats were also investigated using in situ hybridization histochemistry for c- fos mRNA and AVP hnRNA, and immunohistochemistry for Fos. Both plasma AVP and OXT were significantly increased at 5 and 15 min after i.c.v. administration of NPW30 (2.8 nmol/rat). In situ hybridization histochemistry revealed that the induction of c- fos mRNA and AVP hnRNA in the SON and PVN were significantly increased 15, 30, and 60 min after i.c.v. administration of NPW30 (1.4 nmol/rat). Dual immunostaining for Fos/AVP and Fos/OXT revealed that both AVP-like immunoreactive (LI) cells and OXT-LI cells exhibited nuclear Fos-LI in the SON and PVN, 90 min after i.c.v. administration of NPW30 (2.8 nmol/rat). These results suggest that central NPW30 may be involved in the regulation of secretion of AVP and OXT in the magnocellular neurosecretory cells in the SON and PVN.
Quantification of regional cerebral blood flow (rCBF) using N-isopropyl-p-[123I]iodoamphetamine (IMP) and single photon emission computed tomography (SPECT) requires continuous or frequent arterial blood sampling and accurate measurement of radioactivity of many blood samples. In order to avoid these invasive and troublesome procedures, a simplified method with a single blood sampling and two SPECT scans is proposed based on the two-compartment model We tried to find the optimum time of single blood sampling for calibration of the standardized input function. There were ten subjects; four patients with cerebrovascular disease, three with brain tumor, one with head trauma, and two healthy volunteers. Their ages ranged from 25 to 74 years with the average of 56.4 years. IMP (167 MBq) was infused into the right cubital vein at a constant rate in 15 s. Following the start of IMP infusion, arterial blood was sampled from the left radial artery every 15 s for 2 min, every 30 s for the next 3 min, every 1 min for the following 5 min, and with a longer interval thereafter until 40 min after. The radioactivity of the whole blood was counted and its octanol extraction fraction was measured for each sample using the well counter. The whole blood radioactivities obtained at each time point from individual subject were averaged for all 10 subjects. The standardized input function was obtained from the product of the averaged radioactivity of the whole blood and the octanol extraction fraction at each time point. Early and late SPECT data were acquired at mid scan time of 40 min and 180 min, respectively. The rCBF was quantified by the “table-look-up” method. The difference between the standardized input function calibrated at each time point and the individual actual input function was 5.7% at most any time after 3 min and was minimal, 3.6%, at 20 min after the start of IMP infusion. These data were better than the reported minimal value of 5.3% at 9–10 min which were obtained by 1-min IMP infusion. The rCBF values figured out by the present method are well correlated with those calculated by the individual actual input function. An IMP infusion in 15 s with single arterial blood sampling any time after 3 min for calibrating the standardized input function is a practical method for rCBF quantification using IMP SPECT.
Abstract Monitoring the expression of immediate early genes (IEGs) is useful for following stress‐induced cellular responses in the neuroendocrine system. We have examined the transcriptional activities of four IEGs (c‐ fos , jun B, NGFI‐ A and NGFI‐ B) and of the arginine vasopressin (AVP) gene in the hypothalamic paraventicular (PVN) and supraoptic nuclei (SON) of rats after acute osmotic stimuli, using in situ hybridization histochemistry. After intraperitoneal (i.p.) administration of hypertonic saline (2% body weight, 900 mOsm/kg), the expression levels of all IEG mRNAs were increased significantly both in the PVN and SON at as early as 10 min, peaked at 30 min and remained elevated until 60 min. The expression of AVP heteronuclear (hn)RNA also peaked at 30 min, and remained elevated until 180 min. Thirty min after i.p. administration of hypertonic saline (600 mOsm/kg), the expression levels of all IEG mRNAs in the PVN and SON were significantly increased in comparison with those after i.p. administration of isotonic saline (290 mOsm/kg). Regression analysis revealed that expression levels of the IEG mRNAs and AVP hnRNA were positively correlated with the plasma concentration of sodium, and the rates of increase of the expression levels of all IEG mRNAs were similar. The expression levels of all IEG mRNAs examined are useful markers for following the changes of the AVP gene transcription in the PVN and SON after acute osmotic stimuli in rats.
