There are many methods for RNS implementation. The Bajard method is the fastest RNS implementation until now. One of the goals of this paper is to optimize this method to achieve higher performance for hardware implementation of RSA cryptosystem. Higher performance means increase in processing speed and less area. Proper hardware architectures for this method are proposed. For this purpose the number of multiplications is the criterion of the processing speed and the required memory for saving the constant values indicates the area required for this system. The number of multiplications is reduced by 400/(3k+ 11) percent (k is the number of modulus) in the final improved system and the number of constant values reduced by 50 percent.

Large integer modular multiplication and exponentiation are arithmetic primitives required by the public-key cryptosystems. In this paper, an efficient technique to determine the quotient for modular multiplication which is independent of the length of modulus and a 4bits-serial systolic array implementation for high speed modular multiplication are proposed. RSA cryptosystem is used as an example of the application, and the architecture is very suitable for high speed VLSI implementation. Moreover the proposed low-cost implementation (using single processing element (PE)) is feasible in restricted computing environments.

Background: Recurrent spontaneous abortion (RSA) is defined as three or more sequential abortions before the twentieth week of gestation. There are evidences to sup-port an allo-immunologic mechanism for RSA. One of the methods for treatment of RSA is leukocyte therapy; however there is still controversy about effectiveness of this method. Objectives: To evaluate the effectiveness of leukocyte therapy for treatment of RSA. Methods: Ninety two non-pregnant women with at least three sequential abortions (60 primary & 32 secondary aborters) recognized as RSA were referred to our Laboratory for immunotherapy. All the cases were immunized by isolated lymphocytes from their husbands. Fifty to 100 million washed and resuspended mononuclear cells were injected by I.V., S.C., and I.D. route. The result of each injection was checked by WBC cross matching between couples after four weeks of injections. Immunization was repeated in fifth week to a maximum of 3 times if needed. Eighty one age-matched non-pregnant RSA women (52 primary and 29 secondary aborters) with at least three se-quential abortions were also included in this study as controls. The control group was not immunized. Results: 67 out of 92 (72.8%) immunized cases and 44 out of 81 controls (54.3%) showed a successful outcome of pregnancy (p<0.02). Comparison of primary and secondary aborters indicated a significantly better outcome only in primary (75% vs. 42.3%. p<0.001) but not in secondary aborters (68.8% vs. 75.9%, p = 0.7). Conclusion: The present investigation showed the effectiveness of leukocyte therapy in primary but not in secondary RSA patients. Despite the current controversy and limitation of leukocyte therapy in RSA, the results of our investigation provide evidence sup-porting the use of allo-immunization in improving the outcome of pregnancy in primary RSA patients.

Background: Polymorphism A1298C of the methylenetetrahydrofolate-reductase (MTHFR) gene has been implicated in spontaneous abortion. In this study, we determined the allele and genotype frequencies of this polymorphism in recurrent spontaneous abortion (RSA) and implantation failure after in vitro fertilization (IVF).Materials and Methods: We performed a case–control study on 60 women with RSA and 72 women with implantation failure after IVF (both of group have a problem in embryo implantation so, each other compare to health group) and 60 fertile women to investigate the association between MTHFR A1298G, and pregnancy loss by polymerase chain reaction restriction fragment length polymorphism (PCR-RLFP) technique.Results: Among the RSA patients 29 (72.5%) were heterozygote and 7 (17.5%) of them were homozygote for MTHFR mutation. In addition, 46 (63.9%) of IVF failure patients were heterozygote and the frequency of homozygote was 17 (23.6%). While in the control group 28 (56.0%) were heterozygote but none of them were homozygote. So the mutation rate of MTHFR in patients with abortion was statistically different from that in controls. Also significant difference was found in the frequencies of MTHFR between the patients and IVF failure group (p <0.001).Conclusion: Our study revealed that the genotypes of MTHFR A1298C were significantly associated with increased risk of implantation failure of abortion and IVF failure.