For the reception of multicode direct sequence (DS)-CDMA signals, the MMSE frequency domain equalisation is applied instead of RAKE combining. The achievable BER performance in a frequency selective Rayleigh fading channel is evaluated by computer simulation. It is shown by computer simulation that the DS-CDMA with MMSE frequency domain equalisation outperforms the DS-CDMA with RAKE combining and shows only slight performance degradation compared to the MC-CDMA with minimum mean square error combining (MMSEC).

A bone defect that is not repaired with bone completely is designated a non-union defect or a critical-size defect. The biological mechanism that regulates the process of bone repair of the critical-size defect remains unknown. The present study was designed to investigate bone repair in a critical-size defect compared with that in a smaller or non-critical-size defect. Our original standardized rat calvarial bone defect model was used for the experiment. The rate of bone formation was examined with X-ray morphometry and the bone production of osteoblasts and osteocytes was assessed by molecular histology with in situ hybridization for type I collagen and osteocalcin. Formation of repaired bone ceased within 24 weeks in both critical- and non-critical-size defects i.e. regardless of completion of the defect repair. The results suggested that osteoblasts and osteocytes cease bone formation, and the differentiation of osteoblast progenitors declines in 24 weeks. Also, bone repair proceeds from the periosteum on both sides of the parietal bone but not from the surface of the bony edge around the original defect. The results could provide useful information for clinical research on bone repair.

756 CLASSLFICATION OF MALIGNANT LYMPHOMA Acta Path. Jap.form no clear-cut pattern but rather monotonous diffuse masses of round cells which appear to differ only in size. It should be a great hazard not only for treatment of the patients but also for statistical, epidemiological and various other studies on lymphomas that the diagnosis on one tumor would vary according to pathologists who examine it or hospitals where a patient is treated.It is therefore very important to evaluate the general situation on lymphoma diagnosis, to investigate the cause of diagnostic diversity, and to find objective measures to improve the accuracy and reproducibility of lymphoma diagnosis.As seen in the other reports of this symposium, new theoretical and technical approaches based on the recently acquired knowledges on basic immunology have greatly advanced the study of malignant lymphoma.50 It is now apparent that the Rappaport classification (AFIP Atlas, 1966)45 whose clinical usefulness had been widely recognized has some theoretical as well as practical drawbacks. Several different new classifications for non-Hodgkin's lymphomas have been proposed by leading scholars of this field in U.S.A. and E~rope,4,~~,16,16,~~35 and they are a t present being critically evaluated in the project for the international classification of non-Hodgkin's lymphoma sponsored by the National Cancer Institute of U.S.A.It was established through the U.S. -Japan seminars on malignant diseases of hematopoetic system held twice in 1967 and 19712, that the geographic difference between U.S.A. and Japan in various aspects of malignant lymphoma notably in the relative incidence of its subtypes was quite a p~a r e n t .~~~~' In order to contribute to the clarification of the problems of lymphoma diagnosis, and to obtain useful findings for a new classification suited for the lymphomas in Japan, a collaborative study was made by organizing a study group consisting of 16 members of different schools and different length of experience in the pathology of lymphoma. This study consisted of two parts namely I) the study of the consistency and reliabily of the histopathological diagnosis, and 11) the correlation between histological appearances and immunological characters of the lymphoma cells.

In a frequency-selective fading channel, the performance of non-spread-spectrum singlecarrier (SC) transmission degrades significantly due to severe intersymbol interference (ISI). The joint use of space-time transmit diversity (STTD), receive antenna diversity and frequency-domain minimum mean square error (MMSE) equalisation in non-spread SC transmission is studied. Space-time encoding and decoding for frequency-domain MMSE equalisation and receive antenna diversity is presented. The achievable bit error rate (BER) performance of non-spread SC transmission is evaluated by computer simulation. It is found that joint use of STTD, receive antenna diversity and frequency-domain MMSE equalisation can significantly improve the BER performance in a severe frequency-selective fading channel.

The study examined the expression of matrix metalloproteinases (MMPs), type I collagen and osteocalcin during bone healing in a rat calvarial experimental defect model. Twelve-week-old male Wistar rats were used. A full-thickness standardized trephine defect was made in the parietal bone, with the rat under anesthesia. RNA was extracted from tissue that filled the original bone defect on days 1 and 3 and in weeks 1, 2, 3, 5, 8, 10, 12, 18, and 24 and processed for quantitative analysis of expression of type I collagen, osteocalcin and matrix metalloproteinases (MMPs) 2, 8, and 13 by using real-time polymerase chain reaction. Alternatively, the rats were fixed by perfusion through the aorta and resected calvaria were processed for in situ hybridization for these molecules. The expression of type I collagen, osteocalcin and MMPs 2 and 13 increased toward week 2 and decreased thereafter, whereas the expression of MMP 8 was the highest on day 1. The mRNA transcripts of type I collagen and osteocalcin were localized in osteoblasts and osteocytes, some of which expressed MMPs 2, 8, and 13. Osteoblasts and osteocytes may play a role in the remodeling of extracellular matrices with MMPs during healing of a defect in bone.