Characterization of the domains of E. coli initiation factor IF2 responsible for recognition of the ribosome.

We have studied the interactions between the ribosome and the domains of Escherichia coli translation initiation factor 2, using an in vitro ribosomal binding assay with wild-type forms, N- and C-terminal truncated forms of IF2 as well as isolated structural domains. A deletion mutant of the factor consisting of the two N-terminal domains of IF2, binds to both 30S and 50S ribosomal subunits as well as to 70S ribosomes. Furthermore, a truncated form of IF2, lacking the two N-terminal domains, binds to 30S ribosomal subunits in the presence of IF1. In addition, this N-terminal deletion mutant IF2 possess a low but significant affinity for the 70S ribosome which is increased by addition of IF1. The isolated C-terminal domain of IF2 has no intrinsic affinity for the ribosome nor does the deletion of this domain from IF2 affect the ribosomal binding capability of IF2. We conclude that the N-terminus of IF2 is required for optimal interaction of the factor with both 30S and 50S ribosomal subunits. A structural model for the interaction of IF2 with the ribosome is presented.

Bone marrow fibrosis and disease activity in multiple myeloma monitored by the aminoterminal propeptide of procollagen III in serum.

Simple bone marrow fibrosis is seen in 10-30% of multiple myeloma (MM) patients. We investigated the incidence and characteristics of the bone marrow stromal alterations, in order to characterize the collagens involved by immunohistochemistry, and to evaluate the use of serum aminoterminal propeptide of type III procollagen (PIIINP) as a marker of marrow fibrogenesis and disease activity in MM. 34 consecutive patients with newly diagnosed MM were included prospectively, and followed for 12-30 months. Compared with the findings in 15 normal individuals we found increased interstitial deposits of collagen III in 48% of MM patients, whereas deposits of collagen I were not increased. Interstitial fibrosis appeared to be restricted to areas of severe plasma cell infiltration, but it could also have a more dispersed presentation in the severely infiltrated marrow. There was a high co-distribution of collagen III fibrils and reticulin fibres. Serum PIIINP levels were elevated in most patients, and in the follow-up study serum PIIINP showed a good correlation with the response to treatment. Patients with resistant or progressive disease had continually elevated levels of PIIINP. In most patients with responsive disease serum PIIINP normalized, and we observed no relapses in patients who had normal serum PIIINP levels. Other patients who responded to treatment by reduced M-component level, but had persistently elevated serum levels of PIIINP, had either early relapses or developed progression of osteolytic lesions in spite of unchanged M-component levels. Therefore an elevated serum PIIINP during treatment might indicate an active malignant clone. Serum PIIINP does not simply follow the M-component, but gives further information of potential therapeutic value.

Assessment of bone involvement in patients with multiple myeloma using bone densitometry.

To evaluate the use of dual energy X-ray absorptiometry (DXA) in multiple myeloma (MM) we performed a prospective study of 34 patients with newly diagnosed MM. Most patients had advanced disease and all but two patients had osteolytic bone destructions and/or pathological fractures. Bone mineral content (BMC) and bone mineral density (BMD) of the lumbar spine (L1-L4) and hip were measured using a Hologic QDR-1000 scanner. Collapsed vertebrae were not excluded from analysis. Data from 289 healthy Danish volunteers aged 21-79 yr were used for calculation of Z-scores. Lumbar spine BMC (Z-score -0.46 +/- 0.23, p = 0.05) and lumbar spine BMD (Z-score -0.56 +/- 0.23, p = 0.02) were significantly reduced in MM patients, whereas no reduction was seen in hip BMC or BMD. Collapsed vertebrae had marked reduced BMD (Z-score -1.34 +/- 0.22, p < 0.001), as had non-fractured vertebrae in the same individuals (Z-score -1.42 +/- 0.25, p < 0.001). Lumbar spine BMD correlated with radiologically assessed bone morbidity (r -0.37, p = 0.03) and stronger with the incidence of vertebral fractures (r -0.64, p < 0.001). Thus, osteopenia of the back is common in multiple myeloma and correlates with an increased incidence of fractures. DXA may identify subjects with increased risk of vertebral fractures for more intensive chemotherapeutic or anti-resorptive treatment.

Analgesic effect of intra-articular morphine after arthroscopic meniscectomy.

A study was performed to assess the analgesic effect of intra-articular morphine 2 mg in 33 patients undergoing elective arthroscopic meniscectomy. Patients were randomly allocated to receive either 2 mg of morphine hydrochloride in 40 ml of normal saline intra-articularly and 1 ml of normal saline intramuscularly (n = 18), or 40 ml of normal saline intra-articularly and 2 mg of morphine hydrochloride intramuscularly (n = 15). The latter group was to act as a control for any potential systemic effects of the morphine. All patients received an identical general anaesthesia consisting of propofol, alfentanil, enflurane and nitrous oxide/oxygen. No significant differences between the groups were found in pain scores at rest or during active flexion of the knee at 1-6 h postoperatively, or during walking at 6 h postoperatively (p > 0.05). Six and two patients in the intra-articular and intramuscular morphine group, respectively, requested supplemental morphine given intravenously (p > 0.05). In conclusion, no significant differences in pain scores or in requirements for supplemental morphine were observed between patients receiving intra-articular versus intramuscular morphine 2 mg after elective arthroscopic meniscectomy and consequently no specific local analgesic effect of intra-articular morphine could be demonstrated.