Expansion in vitro of retrovirally marked totipotent hematopoietic stem cells

A large number of biologic, technological, and clinical studies await the development of procedures that will allow totipotent hematopoietic stem cells to be expanded in vitro. Previous work has suggested that hematopoiesis can be reconstituted using transplants of cells from long- term marrow cultures. We have used retrovirus mediated gene transfer to demonstrate that marked totipotent hematopoietic stem cells are both maintained and can be amplified in such cultures, and then subsequently regenerate and sustain lympho-myeloid hematopoiesis in irradiated recipients. Marrow cells from 5-fluorouracil-treated male mice were infected with a recombinant virus carrying the neomycin resistence gene and seeded onto irradiated adherent layers of pre-established, long- term marrow cultures of female origin. At 4 weeks, cells from individual cultures were transplanted into single or multiple female recipients. Southern blot analysis of hematopoietic tissue 45 days posttransplantation showed retrovirally marked clones common to lymphoid and myeloid tissues in 14 of 23 mice examined. Strikingly, for 3 of 4 long-term cultures, multiple recipients of cells from a single flask showed marrow and thymus repopulation with the same unique retrovirally marked clone. These results establish the feasibility of retroviral-marking techniques to demonstrate the maintenance of totipotent lympho-myeloid stem cells for at least 4 weeks in the long- term marrow culture system and provide the first evidence of their proliferation in vitro. Therefore, such cultures may serve as a starting point for identifying factors that stimulate totipotent hematopoietic stem cell expansion.     

Modulation of spontaneous outgrowth of Epstein-Barr virus immortalized B-cell clones by granulocyte-macrophage colony-stimulating factor and interleukin-3

Spontaneous outgrowth of immortalized Epstein-Barr virus (EBV) infected B-cell clones will occur from cultures of peripheral blood mononuclear cells (PBMNCs) of some persons with a history of EBV infection. We determined that outgrowth of such clones may be reproducibly modulated by supplementation of cultures with the hematopoietic growth factors GM- CSF and interleukin-3 (IL-3). Continuous supplementation of cultures with GM-CSF facilitates emergence of immortalized B-cell clones, whereas supplementation with IL-3 completely prevents their emergence. The effect of GM-CSF may be direct, at least in part, as the proliferation of pure clones of EBV-transformed B lymphocytes was augmented in response to GM-CSF. An indirect mechanism appears to be responsible for the inhibition of transformed B-cell outgrowth in response to IL-3, as IL-3 had no inhibitory effect on proliferation of pure transformed B-cell clones and IL-3-mediated inhibition could be eliminated by antibody neutralization of gamma-interferon (gamma-IFN) or tumor necrosis factor-alpha (TNF-alpha) early in culture. The mechanisms of these effects deserve further study and may have clinical relevance to use of hematopoietic growth factors for support of bone marrow (BM) function in immunocompromised patients.     

电视腹腔镜外科手术在胃肠道肿瘤的临床应用

目的探讨腹腔镜外科技术在胃肠道肿瘤手术中的应用。方法经电视腹腔镜行胃肠道肿瘤手术１８例,其中右半结肠切除术４例,横结肠癌根治术３例,乙状结肠癌根治术５例,乙状结肠癌姑息切除术并肝转移癌电凝固化１例,胃癌术后复发转移行探查活检１例,胃巨大恶性淋巴瘤行探查活检１例,晚期回肠癌行小肠侧侧吻合术１例,乙状结肠腺瘤切除术２例。结果均获成功,无中转开腹,手术时间平均１６５．０分钟。术后平均３１．２小时胃肠功能恢复,无并发症发生,术后平均住院８．２天。１３例切除肿瘤的结肠癌术后随访２月～３０月,仅１例横结肠癌术后２３月出现肺转移。结论腹腔镜胃肠肿瘤手术损伤小、恢复快、胃肠干扰小、术后疼痛轻,值得进一步探索开展。     

Selenium status of New Zealand infants fed either a selenium supplemented or a standard formula

Objective: New Zealand soils are deficient in the essential micronutrient, selenium. New Zealand infants have low selenium levels at birth and experience a further decline if fed cows milk based formula. This study examined the selenium status of infants fed with a new commercially available selenium supplemented formula.
Methodology Forty-four newborn infants, whose mothers wished to formula feed, were randomized in an open controlled trial to be fed a commercially available selenium supplemented cows milk formula (containing 17 μg Se/L) or an unsupplemented formula (containing 4.6 μg Se/L). Cord, 1 and 3 month blood samples were obtained for selenium status (plasma and red cell selenium and glutathione peroxidase) and thyroid function.
Results Mean plasma selenium and glutathione peroxidase values were significantly higher in supplemented than unsupplemented infants at 1 month (unpaired t -tests; P <0.0001 and P = 0.001 respectively) and 3 months ( P <0.0001 and P = 0.0005). Analysis within treatment groups between time points (paired t -tests) showed that selenium supplementation prevented the fall in plasma selenium from birth to 1 month seen in unsupplemented infants and was associated with a rise in levels between 1 and 3 months ( P = 0.002).
Conclusions Supplementing cows milk formula with selenium to replicate the levels found in breast milk is nutritionally sound. Feeding from a few days of age with a formula containing 17 μg Se/L in infants with low selenium status at birth is sufficient to cause a rise to 80% of adult levels at 3 months of age.     

Langerhans' cell histiocytosis with thyroid involvement masquerading as thyroid carcinoma

A 28-year-old woman was admitted to our Hospital with a chief complaint of progressive gingival swelling and loosening of teeth over about a year. According to past history, she had received total thyroidectomy 2 years previously due to thyromegaly. The thyroidectomy specimen was at first interpreted as 'poorly differentiated carcinoma of the thyroid'. One year ago, she began to be aware of gingival swelling and loosening of teeth. A gum biopsy was taken and the pathologic features were similar to her 'thyroid carcinoma'. Subsequent investigations, including immunohistochemical stain, showed the gum was heavily infiltrated with histiocyte-like Langerhans' cells which were positive for S-100 protein. Ultrastructural examination of the cells under electron microscope revealed many typical intra-cytoplasmic Birbeck granules. Langerhans' cell histiocytosis was diagnosed. Langerhans' cell histiocytosis with thyroid involvement is extremely rare and may run a relatively indolent course. Even on a retrospective examination, it may easily be confused with poorly differentiated carcinoma of the thyroid. We suspect that this error may have been made on other occasions and that the occurrence of this condition may be underreported.      

Treatment related deaths during induction and in first remission in acute lymphoblastic leukaemia: MRC UKALL X

The benefits of achieving a long term event free survival of 60-70% by using increasingly intense treatment regimens must be weighed against the increased risk of treatment toxicity. From 1985 to 1990, 1612 children with childhood acute lymphoblastic leukaemia (ALL) in the UK were treated on MRC UKALL X with intensive induction therapy, central nervous system directed therapy (cranial irradiation and intrathecal methotrexate), and continuing treatment for two years. There was a randomisation to receive blocks of additional intensification treatment at five weeks, 20 weeks, not at all, or both. The five year disease free survival was 71% for children randomised to two blocks of intensification, a 14% improvement on children randomised to no intensification treatment. Treatment related mortality in this national multicentre study has been analysed for induction and first remission (including those after intensification treatment). There were 38 induction deaths, 2.3% and 53 deaths in first remission, 3.3% (including those from a second malignancy). Thirty one (84%) of the induction deaths followed an infection: bacterial in 22 and fungal in nine. Thirty seven infective remission deaths occurred: bacterial in 11, viral in 16, fungal in seven, and three caused by Pneumocystis carinii pneumonia. Ten of these deaths followed a block of intensification treatment. The majority of noninfective remission deaths followed the development of a second tumour. Risk analysis for an induction death showed girls and children with Down's syndrome to be at greater risk. For deaths in first remission analysis showed an increased risk for bone marrow transplant (BMT) patients and children with Down's syndrome. There was no effect of age and leucocyte count for either group. Most significantly when BMT patients were excluded from the analysis, intensification treatment did not increase the risk of remission death.     

Roxatidine versus ranitidine in the treatment of duodenal ulcers: A randomized double-blind controlled multicentre study in Singapore

Roxatidine acetate, a new H₂ receptor antagonist, was compared with ranitidine in the treatment of duodenal ulcers in a double-blind multicentre study. Eighty-four patients with endoscopically proven duodenal ulcer were randomized to receive 150 mg roxatidine acetate or 300 mg ranitidine at bedtime. Repeat endoscopy was performed after 4 weeks (25–33 days) and if the ulcer had not healed, another endoscopy was performed after a further 4 weeks of treatment. Using per protocol analysis 73.6% of ulcers treated with roxatidine healed at 4 weeks compared to 72.2% of ulcers treated with ranitidine (P=NS). The healing rates at 8 weeks were 92% with roxatidine and 83.3% with ranitidine (P=NS). Using equivalence tests, the healing rate of roxatidine was found to be equivalent to that of ranitidine within a 20% region. Roxatidine users took significantly less antacids than ranitidine users (P < 0.05). There were no significant adverse effects due to roxatidine or ranitidine. Roxatidine is a safe effective drug in the treatment of duodenal ulcers with a healing rate comparable to that of ranitidine.