Inhibition of HIV-1 replication by an anti-tat hammerhead ribozyme.

Tat is a virally expressed regulatory protein involved in the replication of HIV-1, the etiological agent of AIDS. To investigate the effect of tat inhibition on HIV replication, we constructed a retroviral vector to express an anti-tat hammerhead ribozyme as part of the 3' untranslated region of beta-galactosidase transcripts. Initial testing of this vector in tat-expressing COS-7 cells reduced tat activity by 85-95% as measured by tat-dependent CAT assays. Amphotropic and HIV-pseudotyped retroviral particles generated with this vector were used in HIV challenge experiments to determine the ability of this reagent to control HIV replication. CD4(+) peripheral blood lymphocytes (PBLs) stably transduced with this vector were subsequently challenged with HIV. These cells were able to resist HIV infection for up to 20 days as measured by cell death and reverse transcriptase activity. These data yield proof of principle that a pseudotyped retroviral vector can target and deliver a protective ribozyme to CD4(+) cells.

Alpha and beta thalassaemia among Chinese children in Guangxi Province, P.R. China: molecular and haematological characterization.

We have studied nearly 100 patients with beta-thalassaemia major and 60 patients with Hb H disease who were attending the Haematology Clinic of Guangxi Medical College. Treatment of the patients was limited and only a few patients with beta-thalassaemia major received blood transfusion(s). As a result, the severe anaemia has led to early death at 3-4 years for beta zero-thalassaemia homozygotes, and 8-12 years for beta(+)-thalassaemia homozygotes. Four beta-thalassaemia alleles are responsible for nearly 90% of all beta-thalassaemia chromosomes. This information has resulted in the initiation of a prenatal testing programme at the local level. The patients with Hb H disease maintained a haemoglobin level of 6-10 g/dl and early death was infrequently observed. The --SEA deletion was the major type of alpha-thalassemia-1, while three smaller deletions (-2.7, -3.7 and -4.2 kb) and two nondeletional alpha-thalassaemia determinants (Hbs Constant Spring and Quong Sze) were the alpha-thalassaemia-2 types.

Types of thalassemia among patients attending a large university clinic in Kuala Lumpur, Malaysia.

We have identified the beta-thalassemia mutations in 59 patients with thalassemia major and 47 patients with Hb E-beta-thalassemia, and the deletional and nondeletional alpha-thalassemia determinants in 23 out of 24 patients with Hb H disease. All persons were attending the Haematology Clinic at the National University of Malaysia in Kuala Lumpur (Malaysia). Most patients (76) were of Malay descent, while 52 patients were Chinese, and two came from elsewhere. The most frequently occurring beta-thalassemia alleles among the Malay patients were IVS-I-5 (G----C) and G----A at codon 26 (Hb E), while a few others were present at lower frequencies. The Chinese patients carried the mutation characteristic for Chinese [mainly codons 41/42 (-TTCT) and IVS-II-654 (C----T)]; Malay mutations were not observed among Chinese and Chinese mutations were virtually absent in the Malay patients. The large group of patients with Hb E-beta-thalassemia and different beta-thalassemia alleles offered the opportunity of comparing hematological data; information obtained for patients with Hb E-beta-thalassemia living in other countries was included in this comparison. Twenty-three patients with Hb H disease carried the Southeast Asian (SEA) alpha-thalassemia-1 deletion; 13 had the alpha CS alpha (Constant Spring) nondeletional alpha-thalassemia-2 determinant, while the deletional alpha-thalassemia-2 (-3.7 or -4.2 kb) was present in 10 subjects. The --/alpha CS alpha condition appeared to be the most severe with higher Hb H values. Both deletional and nondeletional types of alpha-thalassemia-2 were seen among Malay and Chinese patients.

Sickle cell disease in a Brazilian population from Sao Paulo: a study of the beta s haplotypes.

In this study we have determined the frequency of beta S haplotypes in a Brazilian sickle cell disease population from Sao Paulo, Brazil, by analyzing sequence variations in the immediate 5' flanking and second intervening sequence (IVSII) regions of the gamma globin genes. This association between sequence differences and beta s haplotype backgrounds was determined by screening genomic DNA samples using dot blot analysis of polymerase chain reaction products. We studied 148 beta s chromosomes, and found that haplotype 20 (CAR or Bantu) significantly predominated in this population. This is in agreement with the findings of the historical Portuguese Atlantic slave trade from Africa to South America.