Chronically stressed wrists in adolescent gymnasts: MR imaging appearance

PURPOSE

To investigate the magnetic resonance (MR) imaging appearance of a chronically stressed wrist and to assess the utility of MR imaging for evaluation of injuries to the growth plate.

MATERIALS AND METHODS

Coronal T1-weighted spin-echo and gradient-echo MR images were obtained of 93 wrists in 47 high-risk gymnasts of a Chinese opera school. MR imaging and radiographic findings were correlated in 93 wrists.

RESULTS

The major MR imaging abnormalities of 47 radii with abnormal radiographic findings were horizontal fractures (n = 23), physeal cartilage extension to metaphysis (n = 17), and physeal widening (n = 17). The major MR abnormalities of 46 radii with normal radiographs included physeal cartilage extension (n = 12), metaphyseal bone bruise (n = 8), and vertical fractures (n = 4).

CONCLUSION

Physeal cartilage extension into the metaphysis represents a healing sign in chronically stressed adolescent wrists. MR imaging findings including horizontal fracture and physeal cartilage extension to the metaphysis suggest that physeal widening occurred secondary to metaphyseal injury.

The efficacy of postprostatectomy radiotherapy in patients with an isolated elevation of serum prostate-specific antigen

PURPOSE

To determine the efficacy of radiotherapy (RT) in patients with an isolated elevation of prostate specific antigen (PSA) after radical prostatectomy (RP).

METHODS AND MATERIALS

Between November 1987 and May 1993, 53 patients with adenocarcinoma of the prostate were referred for pelvic RT for an elevated PSA after RP. No patient had clinically or radiographically apparent local or distant disease, nor had an undergone prior androgen ablation. Patients received a median dose of 61.2 Gy to the prostatic bed. An undetectable PSA was required to be considered disease free (NED). Univariate and multivariate analyses were performed to identify factors predictive of becoming disease free after RT.

RESULTS

The median follow-up was 15 months. Of the 53 patients, 16 (30%) became NED after RT and 15 (28%) had a declining (n = 11) or stable (n = 4) PSA at last evaluation. The median time after RT to achieve an undetectable PSA was 9.3 months. At 12 and 24 months, the actuarial disease-free survival was 30 and 23%, respectively; actuarial progression-free survival was 71 and 26%, respectively. By univariate analysis, the last PSA level before RT (i.e., the pre-RT PSA) and an undetectable PSA after RP were significant predictors of becoming NED (p = 0.0001 and 0.04, respectively). However, on multivariate analysis, only the pre-RT PSA remained significant (p = 0.01). The mean pre-RT PSA differed significantly between patients who became NED after RT and those who did not (1.5 +/- 0.2 ng/ml vs. 7.6 +/- 1.6 ng/ml, respectively; p = 0.018). Fourteen of 27 (52%) patients with pre-RT PSA levels < or = 2.5 ng/ml became NED, vs. only 2 of 26 (8%) patients with higher levels. There were no severe acute or late sequelae of RT.

CONCLUSION

Prostatic-bed RT for an elevated serum PSA after RP is most effective in patients with a pre-RT PSA < or = 2.5 ng/ml. Patients with significantly higher PSA values are unlikely to benefit from RT, possibly due to the presence of occult distant metastases. The optimal therapy for this latter group remains to be determined.

Modulation of apoptosis by the widely distributed Bcl-2 homologue Bak

Members of the Bcl-2 family of proteins are characterized by their ability to modulate cell death. Bcl-2 and some of its homologues inhibit apoptosis, whereas other family members, such as Bax, will accelerate apoptosis under certain conditions. Here we describe the identification and characterization of a complementary DNA that encodes a previously unknown Bcl-2 homologue designated Bak. Like Bax, the bak gene product primarily enhances apoptotic cell death following an appropriate stimulus. Unlike Bax, however, Bak can inhibit cell death in an Epstein-Barr-virus-transformed cell line. The widespread tissue distribution of Bak messenger RNA, including those containing long-lived, terminally differentiated cell types, suggests that cell-death-inducing activity is broadly distributed, and that tissue-specific modulation of apoptosis is controlled primarily by regulation of molecules that inhibit apoptosis.

Structural and electronic factors in heterolytic cleavage: formation of the Co(I) intermediate in the corrinoid/iron-sulfur protein from Clostridium thermoaceticum

We have completed the first direct structural characterization of an enzyme-bound four-coordinate Co(I) intermediate, in this case for the corrinoid/iron-sulfur protein (C/Fe-SP) from Clostridium thermoaceticum. Extended X-ray absorption fine structure and X-ray edge spectroscopy of the active Co(I) state of the C/Fe-SP indicates a four-coordinate (distorted) square-planar structure where the best fit gives average Co-N(equatorial) distances of 1.87 +/- 0.01 A, corresponding to 4.2 +/- 0.3 ligands. The X-ray edge spectrum of Co(I) C/Fe-SP contains a moderate intensity 1s-4p + "shake-down" (SD) transition and no 1s-3d peak (where SD transitions are indicative of square-planar geometries). X-ray edge results for the methyl-Co(III) form, reported earlier [Wirt, M. D., Kumar, M., Ragsdale, S. W., & Chance, M. R. (1993) J. Am. Chem. Soc. 115, 2146-2150], are consistent with a base-off methylcobamide structure. The absence of a ligated 5-methoxybenzimidazole base in the methyl-Co(III) state is important since the base-off form is predicted to predispose the Co-C bond toward heterolytic cleavage to form the four-coordinate Co(I) species concurrent with methyl transfer. Additionally, we have examined first-derivative X-ray edge spectra of Co(I) C/Fe-SP, relative to edge spectra of a cobalt foil, as an indicator of effective nuclear charge on cobalt. The Co(I) C/Fe-SP edge position at 7720.5 +/- 0.3 eV is less than, but very close to, the value seen for the corresponding free Co(I) cobalamin.(ABSTRACT TRUNCATED AT 250 WORDS)

Collagen structure and cartilage matrix integrity

We continue to explore the molecular interactions that characterize the underlying heteropolymeric assembly of types II, IX, and XI collagen in articular cartilage. Structural studies on bovine articular cartilage reveal a high degree of specificity in the interactions of the individual alpha-chains of types IX and XI collagens. The results predict that type IX collagen molecules are not only heavily crosslinked to type II collagen, in an antiparallel orientation, but also to other type IX collagen molecules through specific sites. Type XI collagen molecules are primarily crosslinked to each other in the tissue, but the results are also consistent with type XI-II covalent interactions. We propose that selective proteolysis of types IX and XI collagens is a potential modulator of collagen network architecture.

Changes in cartilage composition and physical properties due to stromelysin degradation

OBJECTIVE

To determine the effects of stromelysin treatment on biochemical, histologic, and swelling characteristics of intact cartilage explants and to correlate these effects with changes in the functional physical properties of the tissue.

METHODS

Bovine articular cartilage explants were cultured for up to 3 days in the presence or absence of recombinant human stromelysin (SLN). Damage to matrix proteoglycans and collagens was assessed and characterized by N-terminal sequencing and Western blot analysis, respectively. Explants were mechanically tested to assess the ability of the tissue to withstand cyclic and static compressive loads.

RESULTS

Treatment with SLN resulted in a time- and dose-dependent loss of proteoglycans from cartilage explants, with significant loss seen after 3 days of exposure to 20 nM SLN: Histology indicated that initial loss of proteoglycans occurred in regions near the tissue surface and proceeded inward with increasing time of SLN exposure. SLN treatment resulted in degradation of matrix collagen types IX and II, and a concomitant increase in tissue swelling. This matrix degradation resulted in severe alterations in functional physical properties of the tissue, including compressive stiffness. The initial, focal loss of proteoglycans that resulted from SLN treatment was most accurately detected with high-frequency streaming potential measurements.

CONCLUSION

Exposure of intact cartilage to SLN caused specific, molecular-level degradation of matrix molecules, which resulted in changes in the swelling behavior and marked deterioration of functional physical properties of the tissue.

Differentiation of Vibrio vulnificus strains by an arbitrarily primed polymerase chain reaction

A synthetic 17 mer oligonucleotide (5'-GTTGGGTAACGCCAGGG-3') was used as a primer for the arbitrarily primed polymerase chain reaction (AP-PCR) to differentiate various strains of Vibrio vulnificus. A total of 37 genomic DNAs that were extracted from the clinical and environmental strains were successfully differentiated. Among them, 32 profiles of the 37 strains were characterized. None of the environmental and clinical strains had the same amplification profile, suggesting the highly heterogeneous population existed in the strains of V. vulnificus. The size of the amplified sequences ranged from 0.3 to 2.0 Kb and the DNAs were separated to 12 to 20 bands by the 1.2% agarose gel. The clinical isolates from two independent episodes of V. vulnificus infections in a patient were shown to have the same profile, indicating that the second episode was due to recurrence rather than reinfection. The profiles of amplification were reproducible with different preparations of genomic DNA. Arbitrarily primed polymerase chain reaction can therefore be a useful tool for epidemiological study of V. vulnificus infection.

A 92 kDa gelatinase (MMP-9) cleavage site in native type V collagen

Native type V collagen molecules resist mammalian collagenase but are cleaved by certain gelatinases. We report a prominent site of cleavage within the collagen type V molecules by 92 kDa gelatinase (MMP-9). The enzyme was purified from conditioned medium of a rabbit synovial cell line (HIG-82). It cleaved native type V collagen from bovine bone in solution at two molecular sites, one near the amino-terminus, the other producing a 3/5 C-terminal fragment. Amino-terminal sequence analysis of the individual alpha chains from this latter fragment showed that MMP-9 had cleaved between residues Gly439-Val in both alpha 1(V) and alpha (XI) and between residues Gly445-Leu in the alpha 2(V) chain. These sites are close to the previously reported trypsin-cleavage site. The findings imply that gelatinases may be necessary for initiating or completing degradation of type I/type V copolymeric fibrils for growth and remodeling of extracellular collagen.

Management of avulsion injury of the PCL with reattachment

Twenty-eight cases of avulsion injury of the posterior cruciate ligament (PCL) treated by reattachment were followed up to evaluate the results. Evaluation was based on appropriate functional and dynamic criteria: the results are classified as good, fair or poor. The interval between injury and repair ranged from 3 days to 2 months with a mean 4 weeks. The follow-up period ranged from 3 to 10 years with a mean of 5 years. The evaluation revealed 27 (96 per cent) good, one (4 per cent) fair and no poor results. It is apparent that operative reattachment is the treatment of choice for avulsion injury of the PCL, especially in early cases.

Enzyme capture assay for rapid identification of Escherichia coli in blood cultures

An enzyme capture assay (ECA) for rapid identification of Escherichia coli in blood cultures by using beta-D-glucuronidase as a marker was developed. Microdilution plates coated with antiglucuronidase were used to capture this enzyme from the cell lysates of blood cultures which showed growth of gram-negative bacteria. The assay, using 4-methylumbelliferyl-beta-D-glucuronide as a fluorogenic substrate, had a detection limit of 0.1 ng/ml (3 x 10(-13) M) for the enzyme; this was approximately equal to a cell concentration of 10(6) CFU of E. coli per ml. Among 212 blood cultures showing growth of gram-negative bacteria, 77 specimens were found to contain E. coli by conventional culture procedures and 73 samples were positive by ECA. Among the 135 blood cultures from which E. coli was not isolated, ECA gave one false-positive (Salmonella enteritidis) reaction. Thus, the sensitivity and specificity for the identification of E. coli in blood cultures by ECA were 94.8% (73/77) and 99.3% (134/135), respectively. From the finding of positive growth in the culture bottle, the assay can be completed within 4 h. In view of the high rate of isolation of E. coli from bacteremic patients, the test can be performed in parallel with conventional culture protocols; this may shorten the identification time for E. coli, and proper antimicrobial treatments may be started 24 h earlier than when results of conventional identification systems are used.

Management of insufficiency of posterior cruciate ligaments

BACKGROUND

This study aims to evaluate the role of different methods in management of insufficiency of posterior cruciate ligament (PCL) that were used in VGH-Taipei.

METHODS

129 cases with insufficiency of PCL were collected to evaluate, according to functional and dynamic criteria, the results of different managements which were graded as good, fair, or poor. The patients were divided into 3 groups, i.e. group 1 with conservative rehabilitation therapy, group II with surgical reattachment, and group III with surgical ligament reconstruction that had 3 subgroups including IIIa reconstruction with medial head of gastrocnemius, IIIb with patellar tendon and IIIc with artificial ligament. The artificial ligaments used were Leeds-Keio ligament (group IIIcl), Dacron ligament (group IIIc2) and Goretex ligament (group IIIc3). The duration from injury to treatment varied from 3 days to 12 years with mean 45 weeks. The followup period was from 38 months to 112 months with mean 62 months.

RESULTS

The results revealed 6 cases of good grade (25%) and 18 cases of fair grade (75%) in group 1, 20 cases of good grade (95%) and 1 case of fair grade (5%) in group II, 14 cases of good grade (40%), 10 cases of fair grade (29%) and 11 cases of poor grade (31%) in group IIIa, 3 cases of good grade (100%) in group IIIb, 13 cases of good grade (82%) and 3 cases of fair grade (18%) in group IIIcl, 19 cases of good grade (83%), 3 cases of fair grade (12%) and 1 case of poor grade (4%) in group IIIc2, and 3 cases of good grade (43%), 3 cases of fair grade (43%), and 1 case of poor grade (14%) in group IIIc3.

CONCLUSIONS

Conservative intervention could be satisfactory in some cases with PCL insufficiency, especially in cases with isolated PCL injury, while surgical methods is mandatory in the others, especially in cases with chronic symptomatic PCL insufficiency.

Abnormality of type IX collagen in a patient with diastrophic dysplasia

There is growing evidence that a spectrum of chondrodysplasias are caused by mutations in the gene coding for type II collagen. The basic molecular defect in diastrophic dysplasia has not been defined, but it appears not to be in collagen type II. Cartilage contains other tissue-specific collagens, types IX, X, and XI, but no mutations have yet been found in their genes in clinical disease. Type IX collagen is hypothesized to play a role in the regulation of type II collagen fibril organization and structure in cartilage extracellular matrix. In this study, we have examined iliac crest growth cartilage from a patient with diastrophic dysplasia. Although collagen fibrils were markedly increased in diameter on transmission electron microscopy, type II collagen appeared to be normal biochemically. Type XI collagen was also normal. However, type IX collagen appeared abnormal on sodium dodecyl sulfate polyacrylamide gel electrophoresis with a pronounced excess of the COL1 domain of the molecule in pepsin extracts. The findings point to an abnormality in structure or metabolism of type IX collagen in diastrophic dysplasia.

Urgent/emergent percutaneous transvenous mitral commissurotomy

Urgent/emergent percutaneous transvenous mitral commissurotomy (PTMC) was performed in 10 patients (two men and eight women, aged 21 to 60 yr). All patients had arterial hypoxemia and four required mechanical respirators. PTMC was performed in the semi-recumbent position in four patients. The seven patients with pliable valves (group 1) achieved good hemodynamic and echocardiographic results after PTMC, but one died 2 wk later because of sepsis complicating preexisting pneumonitis. The two pregnant patients uneventfully delivered normal babies at term. There was continued clinical improvement in the six surviving patients at last follow-up at 11 to 39 mon (median 26). Of the three patients with calcified valves and severe subvalvular lesions (group 2), the premoribund patient in whom last-resort PTMC created severe mitral regurgitation died 3 days later of multiple organ failure. The other two patients underwent mitral valve replacement 1-6 days later because of lack of clinical improvement due to creation of severe mitral regurgitation and ineffective mitral valve dilation, respectively. In conclusion, urgent/emergent PTMC is feasible and safe. However, its outcomes are dictated by the status of diseased mitral valve and coexisting illness.

Epiphyseal fracture-retrosternal dislocation of the medial end of the clavicle: a case report

Epiphyseal fracture-retrosternal dislocation of the medeial end of the clavicle is an unusual injury. It may occur as a result of a blow either indirectly on the posterolateral aspect of the shoulder girdle or directly over the sternal end of the clavicle. It is clinically impossible to differentiate from the true posterior dislocation even with the computed tomography, but the treatment for either lesion is the same. Recently we uneventually treated a 15-year-old boy with conservative treatment and got a satisfactory result. The purpose of this paper is to draw the attention of the readers to the rarity and serious nature of such injury and the potential difficulties in establishing diagnosis and achieving reduction.

ATPase of Rhodospirillum rubrum requires three functional copies of beta subunit as determined by radiation inactivation analysis

Radiation inactivation analysis yielded a functional unit of 170 +/- 26 kDa as beta subunit of ATPase was irradiated and then reconstituted to beta-depleted chromatophores of Rhodospirillum rubrum. A functional size of 132 +/- 17 kDa for the beta-depleted ATPase moiety involved in ATP hydrolysis reaction was also determined. When both purified beta subunit and beta-depleted chromatophore were irradiated separately, reconstituted, and then activity measured, the functional mass was 312 +/- 50 kDa. Our compelling evidence directly indicates that three functional copies of beta subunits were required for ATP hydrolysis.

Intraoperative epicardial echo/Doppler evaluation of a stentless, chordally supported quadricusp mitral bioprosthesis

The authors have developed a stentless, chordally supported quadricusp mitral bioprosthesis made from bovine pericardium. A large anterior, two commissural, and one posterior cusp all have straight hinge lines and avoid the excessive flexion stress of stent supported valves. The chordal support is concentrated in two flaps for suture to the papillary muscles. Previous in vitro and animal studies demonstrated its superior hemodynamic, biomechanical, and biocompatible behavior over commercial valve bioprostheses. In this study, we further evaluated its in vivo performance by intraoperative epicardial Echo/Doppler immediately after the bioprosthesis was implanted in 10 sheep. In all 10 sheep, Echo showed the valves were similar to native mitral valves in both anatomic appearance and movement. Mitral annular motion and annular-papillary muscle integrity were preserved. In systole, the valves closed competently with chordae moving upward and straightening; in diastole, the valves opened wide with chordae moving downward and relaxing. Color and pulsed Doppler showed no signs of stenosis or regurgitation. In conclusion, the new mitral bioprosthesis provide excellent in vivo performance that mimics the native mitral valve. Intraoperative echocardiography is recommended after mitral valve replacement with such valves.

Clot-blood contrast in fast gradient-echo magnetic resonance imaging

RATIONALE AND OBJECTIVES

Contrast between clot and blood in magnetic resonance imaging (MRI) at 1.5T using fast gradient-echo pulse sequences (fast GRE), with 8 ms < TR < 20 mseconds was studied both in vitro and in clinical human deep venous thrombosis (DVT) to assess whether good contrast could be obtained at such short repetition times and at clinically relevant flow rates.

METHODS

In vitro studies used an apparatus that contained flowing MnCl2[aq] (water adjusted with manganese chloride to have T1, T2 similar to blood) and an immobilized clot (T1, T2 similar to those in DVT) for flow velocities between 0 and 16.5 cm/sec. Seven patients with DVT were imaged with the fast GRE sequences to observe the clot-blood contrast in vivo.

RESULTS

Peak contrast-to-noise ratio (CNR) was achieved using flip angles between 20 degrees and 40 degrees (increasing with flow velocity) with or without radiofrequency "spoiling," consistent with a natural spoiling effect of flow. The CNR between MnCI2[aq] and clot decreased less than 10% as TR was reduced 56% from 18 mseconds to 8 mseconds (30 degrees flip angle). In four patients with nonocclusive DVT, fast GRE imaging provided good contrast while in occlusive cases (three patients) the contrast was not as good as conventional GRE sequences with longer TR values (TR = 33 mseconds).

CONCLUSION

A fast GRE sequence with TR = 8 mseconds, TE = 3 mseconds, and a flip angle = 40 degrees is a promising approach to speeding up the detection of nonocclusive clinical DVT.

Pulmonary valvuloplasty in adults using the Inoue balloon catheter

This report describes a new balloon pulmonary valvuloplasty technique using the Inoue balloon catheter performed in 14 consecutive adult patients, aged 17-47 years (mean 27). The mean right ventricular systolic pressure and the pulmonary valvular peak-to-peak systolic gradient decreased from 102 +/- 41 to 52 +/- 19 mm Hg (p = 0.001) and 81 +/- 40 to 7 +/- 7 mm Hg (p = 0.0002), respectively. An infundibular peak-to-peak systolic gradient either developed (n = 13) or increased (n = 1). None of the patients were treated with beta-adrenergic blockers before or after the valvuloplasty. Eight patients underwent repeat hemodynamic study 12-30 months (mean 17) after treatment, and had no evidence of valvular restenosis. The mean right ventricular systolic pressure and the mean infundibular peak-to-peak systolic gradient decreased, compared to the values immediately after valvuloplasty (54 to 40 mm Hg, p = 0.03, and 28 to 10 mm Hg, p = 0.03, respectively). The study suggests that pulmonary valvuloplasty in adults using the Inoue balloon catheter technique is feasible, safe, and effective.

Functional size analysis of F-ATPase from Escherichia coli by radiation inactivation

A radiation inactivation technique was employed to determine the functional size of adenosine triphosphatase from Escherichia coli (EF0EF1-ATPase). Functional units of the membrane-bound and the soluble ATPases were estimated to be 300 +/- 39 and 295 +/- 32 kDa, respectively. The presence of the free radical scavenger dithiothreitol was crucial in measuring the radiation inactivation size of ATPase. When gramicidin and carbonyl cyanide p-trifluoromethoxyphenylhydrazone were added, an increase in the functional mass of membrane-bound ATPase was observed. In contrast, valinomycin and KCl had hardly any effect on the functional size of ATPase. We also determined a functional unit of 355 +/- 33 kDa for proton translocation by a fluorescence quenching technique. A reconstitution study using irradiated coupling factor 1 (EF1)-depleted membrane revealed that the functional mass of the proton channel was 96 +/- 11 kDa. A similar functional size for ATP-Pi exchange and ATP hydrolysis implies that both reactions might utilize identical machinery. Furthermore, functional units of soluble EF1 for unisite (nonsteady state) and multisite (steady state) ATP hydrolysis were calculated as 200 +/- 32 and 298 +/- 32 kDa, respectively. A working hypothesis was proposed from radiation inactivation analysis to elucidate the structure and mechanism of F1-ATPase.

Coexistence of calcific tendinitis and rotator cuff tear: an arthrographic study

A prospective evaluation of the coexistence of calcific tendinitis and tear of the rotator cuff demonstrated by arthrography was made in patients presenting with shoulder pain. Patients were X-rayed using conventional views and impingement views. Eighty-one patients (mean age 61.2 years) with calcific tendinitis underwent arthrography. Arthrography showed 22 partial or complete tears of the rotator cuff. A small rather than a large amount of calcification was more likely to be associated with a rotator cuff tear (p = 0.005). The coexistence of calcific tendinitis with rotator cuff tear is not uncommon, especially in older age groups.

A positive feedback loop controls transcription of the spoOF gene, a component of the sporulation phosphorelay in Bacillus subtilis

The spo0F gene of Bacillus subtilis encodes a protein that functions as a secondary messenger in a phosphorelay system controlling the initiation of sporulation. Transcription of the spo0F gene was known to be dependent on an intact gene for the transcription regulator Spo0A. In vitro footprint analysis revealed that Spo0A protein bound to two locations in the spo0F promoter region. Deletion of a 40 bp region upstream of one of the promoters (P2) abolished the activation of spo0F expression that occurs at the onset of stationary phase and sporulation. This 40 bp region contains a Spo0A-binding site. These observations are consistent with a hypothesis that Spo0A binding to this region is responsible for activating spo0F transcription. Additionally, Spo0A binding at a downstream site could modulate the level of this activation. Since Spo0F protein is required for the formation of Spo0A-P (the form needed for transcriptional activation) a positive feedback loop controls transcription of spo0F.

Changes in gait and maximum ankle torque in patients with ankle arthritis

Findings from quantitative gait analysis and maximum ankle torque were used to assess the walking pattern of patients with ankle arthritis and to correlate the changes of gait parameters and muscle strength with severity of arthritis. Gait analysis and the isokinetic maximum ankle torque test were performed in 20 patients with first to fourth degree traumatic ankle arthritis. Six patients without evidence of traumatic arthritis were used as controls. Isokinetic maximum ankle plantarflexion and dorsiflexion torques were determined with Cybex instrumentation. Force plate and foot switch data were gathered during level walking. Maximum ankle plantarflexion and dorsiflexion torques were diminished in the injured ankles. Velocity, stride length, and cadence were decreased in arthritic patients compared with controls. The arthritic limbs had shorter single limb stance and longer double stance during free and fast walking speeds compared with the controls' affected ankles. The patterns of ground reaction forces were similar in the injured and uninvolved limbs as well as the control subjects, except the magnitude of vertical forces during push-off were reduced in arthritic ankles. The gait parameters and muscle strength deteriorated as the arthritis became severe, but they showed significant changes only when the patients had third or fourth degree arthritis.

Identification of cross-linking sites in bovine cartilage type IX collagen reveals an antiparallel type II-type IX molecular relationship and type IX to type IX bonding

Type IX collagen functions in covalent cross-linkage to type II collagen in cartilage (Eyre, D. R., Apone, S., Wu, J. J., Ericsson, L. H., and Walsh, K. A. (1987) FEBS Lett. 220, 337-341). To understand this molecular relationship better, an analysis of all cross-linking sites labeled by [3H]borohydride was undertaken using the protein prepared from fetal bovine cartilage. Sequence analysis of tryptic peptides containing the 3H-labeled cross-links showed that each of the chains of type IX collagen, alpha 1(IX), alpha 2(IX), and alpha 3(IX), contained a site of cross-linking at the amino terminus of the COL2 triple-helix to which the alpha 1(II)N-telopeptide could bond. The alpha 3(IX)COL2 domain alone also had an attachment site for the alpha 1(II)C-telopeptide. The distance between the alpha 1(II)N-telopeptide and alpha 1(II)C-telopeptide interaction sites, 137 residues, is equal to the length of the hole zone (0.6D) in a type II collagen fibril. This implies an antiparallel type II to type IX cross-linking relationship. Peptide analysis also revealed an unknown amino acid sequence linked to the COL2 cross-linking domains in both the alpha 1(IX) and alpha 3(IX) chains. Using antibodies to this novel peptide, its origin in the collagen alpha 3(IX)NC1 domain was established. In summary, the results confirm extensive covalent cross-linking between type IX and type II collagen molecules and reveal the existence of type IX-type IX bonding. These data provide a molecular basis for the proposed function of type IX collagen as a critical contributor to the mechanical stability and resistance to swelling of the collagen type II fibril framework of cartilage.

Shoulder impingement syndrome: impingement view and arthrography study based on 100 cases

A prospective evaluation combining the shoulder impingement view and arthrography was made in patients presenting with chronic shoulder pain. Five hundred and twenty-three patients with chronic shoulder pain were X-rayed using conventional views and impingement views. One hundred of these patients (mean age 62 years) had subacromial bony spurs on the impingement view; these underwent arthrography. They were divided into two groups according to the degree of spur formation--whether or not the size of the spur exceeded one half of the acromial width as measured from the outer margin to the acromioclavicular joint. Of the 100 subacromial spurs demonstrated on the impingement view, only 18 were visible on the conventional view as assessed by an independent radiologist. Arthrography showed 35 cases of rotator cuff tear. The size of the bony spur was strongly associated with the incidence of rotator cuff tear (P < 0.02).