Structure of the human transcription factor TFIIF revealed by limited proteolysis with trypsin.

In this study, the human general transcription factor IIF (TFIIF), a heteromeric complex of RAP74 and RAP30 subunits, was subjected to limited proteolysis with trypsin. The central region of RAP74 was demonstrated to be highly sensitive to trypsin while both the N- and C-terminal regions contained trypsin-resistant structures. In contrast, RAP30 digestion occurred after proteolysis of RAP74. The digestion pattern of RAP74 recruited into the preinitiation complex showed no marked difference from that of IIF, while RAP30 in the complex was protected from trypsin. These results indicate that RAP74 apparently contains three structural domains, the central one of which is externally surfaced and unstructured, but RAP30 is internally wrapped by RAP74. Furthermore, the accessibility of the central region of RAP74 is unaltered in the minimal preinitiation complex, while RAP30 is involved in promoter recognition through its DNA binding activity.

Upsizing the femoral component increases patellofemoral contact force in total knee replacement.

In posterior stabilised total knee replacement (TKR) a larger femoral component is sometimes selected to manage the increased flexion gap caused by resection of the posterior cruciate ligament. However, concerns remain regarding the adverse effect of the increased anteroposterior dimensions of the femoral component on the patellofemoral (PF) joint. Meanwhile, the gender-specific femoral component has a narrower and thinner anterior flange and is expected to reduce the PF contact force. PF contact forces were measured at 90°, 120°, 130° and 140° of flexion using the NexGen Legacy Posterior Stabilized (LPS)-Flex Fixed Bearing Knee system using Standard, Upsized and Gender femoral components during TKR. Increasing the size of the femoral component significantly increased mean PF forces at 120°, 130° and 140° of flexion (p = 0.005, p < 0.001 and p < 0.001, respectively). No difference was found in contact force between the Gender and the Standard components. Among the patients who had overhang of the Standard component, mean contact forces with the Gender component were slightly lower than those of the Standard component, but no statistical difference was found at 90°, 120°, 130° or 140° of flexion (p = 0.689, 0.615, 0.253 and 0.248, respectively). Upsized femoral components would increase PF forces in deep knee flexion. Gender-specific implants would not reduce PF forces.

The biomechanical assessment of gap formation after flexor tendon repair using partial interlocking cross-stitch peripheral sutures.

The gap formation of five core plus peripheral suture techniques for flexor tendon repair was evaluated by cyclic load testing. Fifty pairs of dental roll tendon models were sutured using six-strand Pennington modified Kessler core suture with 4-0 Polypropylene. One-half or three-fourths circumferential interlocking cross-stitch, or three complete circumferential peripheral suture techniques were performed using 6-0 Polypropylene. An initial cyclic load of 10 N for 500 cycles was applied and increased by 5 N for an additional 500 cycles at each new load until rupture. The complete circumferential interlocking cross-stitch had the greatest fatigue strength. The partial circumferential cross-stitches resulted in significantly larger gap formations at both the repaired and unrepaired sides than the complete circumferential sutures, and were also associated with early rupture. The full circumference of the cut tendon must be sutured using an interlocking cross-stitch peripheral suture to improve strength and avoid gap formation.

Enlarged post-operative posterior condyle tightens extension gap in total knee arthroplasty.

We investigated whether the extension gap in total knee replacement (TKR) would be changed when the femoral component was inserted. The extension gap was measured with and without the femoral component in place in 80 patients with varus osteoarthritis undergoing posterior-stabilised TKR. The effect of a post-operative increase in the size of the femoral posterior condyles was also evaluated. The results showed that placement of the femoral component significantly reduced the medial and lateral extension gaps by means of 1.0 mm and 0.9 mm, respectively (p < 0.0001). The extension gap was reduced when a larger femoral component was selected relative to the thickness of the resected posterior condyle. When the post-operative posterior lateral condyle was larger than that pre-operatively, 17 of 41 knees (41%) showed a decrease in the extension gap of > 2.0 mm. When a specially made femoral trial component with a posterior condyle enlarged by 4 mm was tested, the medial and lateral extension gaps decreased further by means of 2.1 mm and 2.8 mm, respectively. If the thickness of the posterior condyle is expected to be larger than that pre-operatively, it should be recognised that the extension gap is likely to be altered. This should be taken into consideration when preparing the extension gap.

Strength enhancement of the interlocking mechanism in cross-stitch peripheral sutures for flexor tendon repair: biomechanical comparisons by cyclic loading.

The fatigue strength of three peripheral suture techniques for flexor tendon repair was compared by cyclic loading of repairs in a cotton dental roll tendon model. Thirty pairs of dental roll were sutured using only peripheral sutures with 6-0 polypropylene. An initial cyclic load of 5 N for 500 cycles was applied and increased by 5 N for an additional 500 cycles at each new load until rupture. The fatigue strength of an interlocking cross-stitch suture was 113% greater than a running suture and 36% greater than a standard cross-stitch suture. Interlocking the cross-stitch prevented shortening of the transverse portions under load and appears to be a useful technique for increasing the strength of the peripheral suture.

Novel polymorphisms in the upstream region of the human dopamine D4 receptor (DRD4) gene.

We found nine novel polymorphisms in the upstream region of the human dopamine D4 receptor (DRD4) gene of Japanese by direct sequencing. These polymorphisms are -809G > A, -768G > A, -616C > G, -603T > del, -602G > del, -600G > C, -376C > T, -291C > T, and -128G > T. One known polymorphism, -521C > T, was also recognized. Six of these sites were identified as restriction fragment length polymorphisms (RFLPs).

Clinical features of multiple epiphyseal dysplasia expressed in the knee.

The purpose of this study is to clarify the clinical features of the knee affected by multiple epiphyseal dysplasia. Thirty-one cases of multiple epiphyseal dysplasia were reviewed. Of the patients, 11 were male and 20 were female. The average age at onset of symptoms was 22.5 years. The average age at initial visit to the authors' hospital was 28.9 years. Radiographic findings showed epiphyseal abnormality of the knee in all but two (93%) cases. Irregularity, segmentation of the epiphysis, widening of the joint space, and genu valgum deformity were the dominant findings before epiphyseal closure. After epiphyseal closure, the most characteristic finding was a shallow femoral trochlear groove, which was observed in 56.5% of the cases. Other findings in adult patients included early onset osteoarthritic change, genu valgum, depression of the lateral tibial plateau, and multiple free bodies. However, there still is a possibility that multiple epiphyseal dysplasia exists, even if the patient lacks a shallow femoral trochlear groove. If genu valgum or varum, free bodies, and premature osteoarthritis are observed, one should evaluate other joints, keeping a diagnosis of multiple epiphyseal dysplasia in mind. Patients with knees that have a femoral trochlear groove of normal or near normal shape do exist, and premature osteoarthritic changes may develop in such patients.

Association analysis of polymorphisms in the upstream region of the human dopamine D4 receptor gene (DRD4) with schizophrenia and personality traits.

The human dopamine D4 receptor (DRD4) is of major interest in molccular studies of schizophrenia and personality traits. We examined the association of schizophrenia and polymorphisms in the upstream region of the DRD4 gene (-768G>A in the negative modulator region; -521C>T, -376C >T, and -291C>T in the cell type-specific promoter region; and -616C>G between the two regions) in 208 schizophrenic patients and 210 normal controls. No significant difference in genotype and allele frequencies was observed between the two groups, indicating that these polymorphisms do not make a major contribution to the pathogenesis of schizophrenia. We also studied the association of polymorphisms in the upstream region and a 48-bp repeat polymorphism in exon III of the DRD4 gene with personality traits in 173 Japanese individuals who completed the temperament and character inventory (TCI). The -768G>A polymorphism was significantly associated with reward dependence (P= 0.044), while no significant association was observed between novelty seeking and polymorphisms in the upstream region or the exon III repeat polymorphism of the DRD4 gene.

Antagonistic effects of an alternative splice variant of human IL-4, IL-4delta2, on IL-4 activities in human monocytes and B cells.

IL-4 is a pleiotropic cytokine which exerts its actions on various lineages of hematopoietic and nonhematopoietic cells. This cytokine is one of the central regulators of immunity in health and disease states. An alternative splice variant, in which the second of four exons is omitted, has been recently described and designated as IL-4delta2. The variant has been previously described as a potential naturally occurring antagonist of human IL-4 (hIL-4)-stimulated T cell proliferation. In this study, we investigated the effects of recombinant human (rh) IL-4delta2 on monocytes and B cells. In monocytes, rhIL-4delta2 blocked inhibitory action of hIL-4 on LPS-induced cyclooxygenase-2 expression and subsequent prostaglandin E2 secretion. In B cells, rhIL-4delta2 was an antagonist of the hIL-4-induced synthesis of IgE and expression of CD23. Our results broaden the spectrum of hIL-4-antagonistic activities of rhIL-4delta2, thus creating the background for the potential use of rhIL-4delta2 as a therapeutic anti-hIL-4 agent.

Cutting edge: dominant effect of Ile50Val variant of the human IL-4 receptor alpha-chain in IgE synthesis.

Two variants of the IL-4R alpha-chain (IL-4Ralpha) gene have been recently identified in association with different atopic disorders. To clarify the etiological relationship between the two variants, we analyzed responsiveness to IL-4 of transfectants with four kinds of IL-4Ralpha carrying either Val or Ile at 50 and either Gln or Arg at 551. The substitution of Ile for Val augmented STAT6 activation, proliferation, and transcription activity of the Iepsilon promoter by IL-4, whereas that of Arg for Gln did not change these IL-4 signals. Arg551 was not associated with atopic asthma in the Japanese population. CD23 expression and IgE synthesis by IL-4 were augmented in Ile50-bearing PBMC, compared with those bearing Val50. Taken together, substitution of Arg551 does not enhance the IL-4 signal for generation of germline epsilon transcript, whereas the substitution of Ile50 contributes to enhancement of IgE synthesis.