ABSTRACT
This work describes a novel approach for Al-7.5Si/Al-18Si liquid-liquid bimetal casting in sand and metallic moulds. The aim of the work is to facilitate and develop a simple procedure to produce an Al-7.5Si/Al-18Si bimetallic material with a smooth gradient interface structure. The procedure involves the theoretical calculation of total solidification time (TST) of the first liquid metal (M1), pouring the liquid metal (M1), and allowing it to solidify; then, before complete solidification, the second liquid metal (M2) is introduced into the mould. This novel approach has been proven to produce Al-7.5Si/Al-18Si bimetal materials using liquid-liquid casting. The optimum time interval of Al-7.5Si/Al-18Si bimetal casting with modulus of cast Mc ≤ 1 was estimated based on subtracting 5-15 s or 1-5 s from TST of M1 for sand and metallic moulds, respectively. Future work will involve determining the appropriate time interval range for castings having modulus ≥ 1 using the current approach.
ABSTRACT
Asymmetric dimethylarginine (ADMA) level may play a role in the pathogenesis of cerebrovascular stroke in Children with Sickle Cell Anemia (SCA). To assess the plasma level of ADMA in children with SCA and its correlation to cerebral blood flow. This is a cross sectional study was carried out on 30 children with homozygous SCA under follow up in the Out Patients Clinic, Pediatric Department at Tanta University Hospital and 30 healthy children as a control group. Both groups had undergone the following investigations: Complete blood count, lactate dehydrogenase enzyme, and plasma level of ADMA by a commercial ADMA ELISA Kit. Trans-cranial Doppler were done for both groups. ADMA plasma level was significantly higher in-patient group in comparison to the control group (p < 0.001), with a mean value 1.43 ± 0.20 µmol/l, 0.48 ± 0.16 µmol/l respectively. The time-averaged mean maximum velocities for middle cerebral artery, anterior cerebral artery, inferior cerebral artery and posterior cerebral artery were significantly different between patient and control group, p < 0.05. Trans-cranial Doppler data revealed that, 86.7% of patients have low velocity (< 70 cm/s) and 13.3% having very low velocity (< 10 cm/s) while control group have normal velocity. There was a significant negative correlation between ADMA plasma levels and cerebral blood flow. Elevated ADMA levels may have a role in the pathogenesis of the decreased cerebral blood flow in children with SCA.
ABSTRACT
The present study was conducted to compare between the therapeutic efficacies of human amniotic membrane-derived stem cells (hAM-MSCs) vs. adipose tissue derived stem cells (AD-MSCs) in cyclophosphamide (CTX)-induced ovarian failure in rats. Forty-eight adult female rats were included in the study; 10 rats were used as control group. Thirty-eight rats were injected with CTX to induce ovarian failure and divided into four groups: ovarian failure (IOF) (IOF group), IOF + phosphate buffer saline (PBS group), IOF + hAM-MSCs group and IOF + AD-MSCs group. Serum levels of FSH and estradiol (E2) were assessed. Histopathological examination of the ovarian tissues was performed and quantitative gene expressions of Oct-4, Stra8 and integrin beta-1 genes were conducted by quantitative real time PCR. Results showed that IOF and IOF + PBS rat groups exhibited decreased ovarian follicles, increased interstitial fibrosis with significant decrease of serum E2, significant increase serum FSH level and significant down-regulation of Stra8 and integrin beta-1. In hAM-MSCs and AD-MSCs rat groups, there were increased follicles and corpora with evident the presence of oocytes, significant increase in serum E2, significant decrease in serum FSH levels (in hAM-MSCs treated group only) and significant up-regulation of the three studied genes with higher levels in hAM-MSCs treated rats group when compared to AD-MSCs treated rats group. In Conclusion, administration of either hAM-derived MSCs or AD-MSCs exerts a significant therapeutic efficacy in chemotherapy induced ovarian insult in rats. hAM-MSCs exert higher therapeutic efficacy as compared to AD-MSCs.
